CGRI 2012-51

Unlimited Release

Printed May 2012




Disadvantages and hazards in Using Lasers for Explosives Detection:

Final Report




Prepared by

C.G.R.I. Laboratories

Simis 15, Nikosia 2044, Cyprus, EU



C.G.R.I. laboratories operated by C.G.R.I. Ltd,

for Kyklotron Ltd Company, Cyprus, EU



Konstantinos Stromatias,

Greek Army Brigadier (ret) , Branch of Combat Engineers & Informatics

Microelectronics systems Designer - Inventor Researcher
BSc in Greek Military Academy

MSc in Microelectronics and Computer Engineering

PhD candidate in Geophysics

Editor: "www.kyklotron.com , http://www.cgri.gr , http://www.geoment.e-e-e.gr



Cyprus Geopathetic Research Institute Laboratories


NOTICE: This report was prepared as an account of work sponsored by yklotron ltd, Cyprus, EU. Neither the yklotron ltd, nor any agency thereof, nor any of their employees, nor any of their contractors, subcontractors, or their employees, make any warranty, express or implied, or assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represent that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the yklotron ltd, any agency thereof, or any of their contractors or subcontractors.

The views and opinions expressed herein do not necessarily state or reflect those of the yklotron ltd, any agency thereof, or any of their contractors.













CGRI 2012-51

Printed May 2012




Disadvantages and hazards in Using Lasers for Explosives Detection :

Final Report






Contraband Detection Department





C.G.R.I. Laboratories


Simis 15, Nikosia, Cyprus, EU










Continued acts of terrorism using explosive materials throughout the world have led to great

interest in long distance explosives detection technology, especially technologies that have a potential for remote on detection. This report was undertaken to investigate of the disadvantages and hazards in using of quantum cascade lasers (QCL) in long distance explosives detection systems.








The authors acknowledge the contributions provided by the Early Warning Systems R & D Department, C.G.R.I. Laboratories













1. Introduction

1.1 Background

1.2 Overview

1.3 Purpose

1.4 Objectives

2. Discussion

2.1 Basics on Raman Spectroscopy

2.2 Basic Laser - Based Optical Stand-off Spectroscopy

2.2.1 Explosive detection using infrared laser spectroscopy

2.2.2 Quantum Cascade Lasers (QCLs) for Standoff Explosives Detection

3. A typical Laser-based Stand-off Explosives Detection system in action

4. QCLs products in determine explosives detection

4.1. ASTAMIDS Fly-By Mine Detectors

4.2 Detecting explosives from a distance with laser beams

4.3 Standoff detection of explosives with external cavity quantum cascade

5. Could QCLs detect explosives in long range ?

6. Could QCLs detect explosives when a parapet is in front of them ?

6.1 Reflection and Absorption of Laser Beams

6.2 Materials resistant to radiation and beam impact

6.3 Fullerene films highly resistant to laser radiation

7. Could QCLs tech interfered and how ?

7.1 Common optical CDs and DVD s disks LASER beam absorning

7.2 LASER beam can be bounced off of mirrors

7.2.1 Using Just simple MIRRORS !!!

7.2.2 LASER beam can be bounced off of Crystals


7.3 Air vacuum and Spreadable molecules

7.3.1. What is vacuum ?

7.3.2 How to create vacuum Claw type vacuum pumps The Claw Principle Vacuum food saver boxes as an anti-LASER detector solution Vacuum Pump for laboratories VACUVIN - Vacuum food saver boxes Pump engineered for make vacuum in containers.

7.4 Anti LASER systems. A LASER SHIELD for LASER beams.

7.5 Pyrotechnic composition for producing radiation-blocking screen

7.6 Large, single-domain crystals of KTA and RTA commercially available.

7.7 Coherent perfect absorbers (CPA) Anti-lasers spawn





8. Is QCLs tech a safe tech for QCL system users and people around ?

8.1 About LASER

8.2 Hazards from LASER use

9. Could terrorists cause problems to QCL tech systems for explosives detection ?

10 . Directed-energy weapons problems

10.1 Problems and considerations

10.1.1 Blooming

10.1.2. Evaporated target material

10.1.3. High power consumption

10.1.4. Beam absorption

10.1.5. Lack of indirect fire capabilities

10.2 Lasers

10.3 Electrolaser

10.4 Radio frequency

10.5 Microwaves

10.6 Pulsed Energy Projectile

10.6.1 Effects and Uses

11. Conclusions

12. References




Figure 1. Raman spectroscopy system

Figure 2. Raman transitional schemes

Figure 3. Raman Spectroscopic system

Figure 4. Raman principal

Figure 5. Energy level diagram showing the states involved in Raman signal

Figure 6. Feynman diagram of scattering between two electrons

Figure 7. The different possibilities of visual light scattering

Figure 8. Phase 1. Laser beam target the explosive matter

Figure 9. Phase 2. Laser beam pulse hits the explosive matter

Figure 10. Phase 3. The vapor results

Figure 11. Details of the vapor results

Figure 12. Phase 4. Molecules on air around target

Figure 13. Phase 5. Representation how QCLs tech works in action

Figure 14. Schematic of a QCL system & subsystems

Figure 15. ASTAMIDS Target Acquisition and Minefield Detection System

Figure 16. Light transmission in medium

Figure 17. A Compact Disk (CD) icon and a digital representation

Figure 18. CD details in how it works

Figure 19. CD , the burning surface that absorbs LASER beams

Figure 20. Common mirror , like those on common cars front glasses.

Figure 21. Crystal and laser beam bounced off

Figure 22. Prismatic Crystal and laser beam bounced off

Figure 23 Cooper type LASER reflectors

Figure 24 How pump works

Figure 25 Inside a pump

Figure 26. A vacuum pump

Figure 27. A cutaway view of a turbomolecular high vacuum pump

Figure 28 The Rietschle claw pump

Figure 29. A typical vacuum pump for laboratories

Figure 30. Vacuum food saver boxes

Figure 31 Pump engineered for make vacuum in containers

Figure 32. A LASER SHIELD for LASER beams.

Figure 33. A domestic SHIELD for LASER beams.

Figure 34. A helium-neon laser demonstration at the Kastler-Brossel Laboratory

Figure 35. Components of a typical laser

Figure 36. Stimulated emission from a LASER

Figure 37. Solid State Laser Diagram

Figure 38. Three level laser energy diagram

Figure 39. Semiconductor laser diagram

Figure 40. Gas laser diagram

Figure 41. Common Dye Laser Diagram

Figure 42. Free Electron Laser Diagram

Figure 43 Common TEM laser beam modes

Figure 44. Warning symbol and labels for lasers

Figure 45. Anti - QCL tech lethal trap for detection systems using LASER beams

Figure 46. A QCL detection systems blasting an IDE using LASER beam

Figure 47. In combat use LASER




Table 1 : Some material's optical properties (under 1.06 micro radiation)

Table 2. Common Lasers and Their Wavelengths









IED Improvised explosive device

LDCDD Long distance chemical detection devices

IR infrared

MIR mid-infrared

QCL quantum cascade laser

RDX cyclotrimethylenetrinitramine

TNT 2,4,6 trinitrotoluene

VBIED vehicle-borne improvised explosive device

m micrometer








Executive Summary


Terrorism around the world always existed. Is not something new, even that some guys seems that discover it now days.


Ideas and thoughts as : led to great interest in long distance explosives detection technology using explosive materials , is not also something new. Except a small detail. Up to now only British companies have the big deals - serious economic contracts - in explosives detection systems around the world. Up to now.


There is some tendency to argue that explosives research in long distance is difficult and almost impossible. U.S. Army, mostly , neglects old technologies in explosives detection such as Paramagnetism tech and QNR tech is.


At 9 July 2008, published the technical report by the name Explosives Detection Using Magnetic and Nuclear Resonance Techniques by Jacques Fraissard and Université Pierre et Marie Curie Ecole de Physique et Chimie Industrielles, Paris, France & Olga Lapina Boreskov Institute on Catalysis Russian Academy of Sciences, Novosibirsk, Russia.

Springer Science + Business Media B.V. 2009

Proceedings of the NATO Advanced Research Workshop on

P.O. Box 17, 3300 AA Dordrecht, The Netherlands.

79 July 2008

ISBN 978-90-481-3061-0 (PB) - ISBN 978-90-481-3062 -7 (e-book) - ISBN 978-90-481-3060-3 (HB)

Explosives Detection Using Magnetic and Nuclear Resonance Techniques

Library of Congress Control Number: 2009929398

St. Petersburg, Russia


This work is about using QNR technology in explosives detection. In this repot referred that

If NQR is so good, why it is not used everywhere?


The main limitation is the signal-to-noise ratio, particularly with the interference that exists in a field environment, because of the fact that NQR polarization is much weaker than that from an external magnetic field. The distinctive signatures are there, but the sensitivity is so poor that the signatures are difficult to pull out of the noise.


The typical NQR signal is weaker than the thermal noise in the detector circuit.


External sources of radio frequency interference also make detection difficult. Fortunately, methods to coherently manipulate the NQR signal exist, and these methods can be used to increase the signal amplitude and reduce interference.


In addition the high selectivity is partly a disadvantage, as it is not easy to build a multichannel system necessary to cover a wide range of target substances.


Also it is difficult to detect substances fully screened by metallic enclosures, etc.


The Naval Research Laboratory in the USA and the Kaliningrad Institute in Russia are the most important research centres in this field.


However, there are many other laboratories working to improve the sensitivity of NQR for the detection of explosives, albeit in a completely independent fashion.

The aim of this workshop was to bring together everybody interested in this question in an attempt to make NQR the universal technique for the detection of bombs regardless of type, even in the form of mixtures of explosives.


The choice of Russia as the venue for this meeting is not arbitrary. This country is one of those particularly subject to terrorist attacks. However, due to the economic situation in Russia, communication with the researchers from partner countries has been quite limited. Such a workshop can help to foster constructive interaction to the benefit of this specifically crucial field.


The conference took place in the University of Saint Petersburg, situated in the heart of old city, on the bank of the Neva river, in front of the Hermitage and the Saint Isaac Cathedral (17831789).


We must thank the authorities of this university which gave us the magnificent Petrosvsky hall, the only hall in the Twelve Colleges which is still in its original Baroque style, practically intact since its construction under Peter the Great in 1724.


Many people have contributed to the success of the ARW on which this volume is based. We thank of course all participants for contributing to the intellectual dialogue. It is also a great pleasure to acknowledge the main financial support provided by the Scientific Affairs Division of the North Atlantic Treaty Organization (NATO).


Those 16 projects papers about this work dont recover any element that could neglect the NQR tech in explosives detection. This is my conclusion.


Just a year before U.S. Army issued specifications in order to supply long distance chemical detection devices that will be able to sense the presence of explosives and chemicals on people standing, walking, or running from as far away as 100 yards (91 meters) .


Devices should be capable of being mobile as the Army intends to mount them on extendable masts on vehicles. In addition, the sensors must be able to detect explosives with an accuracy of two centimeters on people approaching at twelve miles per hour at a range of 330 feet during daytime, night time, and poor weather situations. The detection system should process data at a mobile workstation in a vehicle. That data would then be streamed via RF data link to a central processing and analysis station. The Army has chosen to pursue hyper-spectral sensor solutions over multi-spectral sensors due to their increased sensitivity and ability to detect more subtle variations. Multi-spectral imagery relies on sensors that measure the amount of reflected energy within a specific set of bands within the electromagnetic spectrum, like visible greens and reds. In contrast, hyper-spectral sensors have the ability to measure reflected energy along a broader number of electromagnetic bands and more sensitive to fluctuations in reflected energy.


We, here in C.G.R.I do not understand and interpret the term LONG DISTANCE , as we have been developed explosives detection and localization systems (www.kyklotron.com ) in range far over 20.000 meters


If 91 meters are interpret as LONG , the > 20.000 meters interpret as what ?


It is not of course our problem, but we consider


We, here in C.G.R.I. also consider that long distance explosives research is difficult but not impossible. In C.G.R.I. we R & D for Kyklotron ltd many systems for detecting , localizing and digital recording of material structures (not only explosives ) as the DRAMS Early Warning System is ( www.kyklotron.com ) . We do R & D Since 2004 .


We, in C.G.R.I also consider that Long distance term, is not something that must somebody define just like this. Just so that his technology could reach to. But this is not our problem.


As I am a Greek (Greek is in NATO) Army Brigadier (retired), in Branch of Combat Engineers, well trained in explosives for over 33 years, the first thing I have been told, in explosives handling, was the safety range from the explosives. NATO military books (Greece uses USA military material and systems at Combat Engineers Corp) defines AT LEAST 300 meters away as a safety range for a 1 pound (1/2 kg) of TNT explosive existence. This is the safety range for any trainer, military officers in NATO in training others to explosives handling.


Its very difficult to me to understand why the 91 meters range are defined as long distance detection range for LDCDD using QCLs systems.


A range of 91 meters could not cover any safety rule for the personnel that uses. LDCDD using QCLs systems.

There is no IDE or land mine or explosive matter or trap using only 1 pound of explosive.

  • A land mine uses about 5 kilos (10 pounds) of TNT explosive matter.
  • In India GRAY HOUND told us that terrorists use 100 kilos of ANFO explosive matter in traps bombs as IDE.
  • In S.A. , PSD told us that a terrorist usually carries over 10 kilos of TNT.


What is really going to happen if the IDE or explosive matter or land mine explodes inside the 91 meters range ?


We cannot find an answer...


Are those long distance chemical detection devices could not detect explosives over 91 meters long ?


Raman Spectroscopy tech, used in QCL quantum cascade laser for explosives detection , is not something new. Ramman Spectroscopy tech is an 1928 year tech.


new tech from 1928


This report was undertaken to investigate the potential disadvantages and hazards of utilizing quantum cascade lasers in detection systems. This report documents the potential opportunities that C.G.R.I. Laboratories can contribute to the field of long distance explosives detection development. The following is a list of QUESTIONS where the results of this report can answer :


Could QCLs determine optimal explosives detection ?

Could QCLs detect explosives in long range ?


Could QCLs detect explosives when a parapet is in front of them ?


Could QCLs tech interfered and how ?


Is QCLs tech a safe tech for QCL system users and people around ?


Could terrorists cause problems to QCL tech systems for explosives detection ?


  Is Laser tech a safety tech in the field ?


  What are the basic problems of the Directed-energy weapons ?








1. Introduction


1.1 Background

Increased domestic and troop security could be achieved through detection of improvised explosive devices (IEDs), and vehicle-borne improvised explosive devices (VBIEDs). An effective explosives detection capability would save lives and prevent losses of mission-critical resources by increasing the distance between the explosives and the intended targets and/or security forces. Many governments in the world are urgently attempting to obtain useful equipment to deploy to their troops currently serving in hostile environments.


Recent developments in optoelectronics have enabled significant advances in quantum cascade lasers.


QCL system size has been reduced from large laboratory laser table size to small rugged field-size units.


QCL have increased their power output to Watts, which enable long - distance applications.


QCL wavelengths are dependent on fabrication design and can be tailored to specific wavelengths.


The U.S. Army is seeking to rapidly deploy long distance chemical detection devices that are capable of detecting explosives hidden on people; ideally, the devices will be able to sense the presence of explosives and chemicals on people standing, walking, or running from as far away as 100 yards; the Army wants to be able to field these capabilities within a year, so it is only considering mature technologies that are ready to be implemented; the request for proposals will close on 6 May. The U.S. Army is seeking to rapidly deploy long distance chemical detection devices that are capable of detecting explosives hidden on people. Ideally, the devices will be able to sense the presence of explosives on people standing, walking, or running from as far away as 100 yards. The Army wants to be able to field these capabilities within a year, so it is only considering mature technologies that are ready to be implemented. On Wednesday, the Army Night Vision and Electronic Sensors Directorate at Fort Belvoir, Virginia issued a sources-sought notice specifically for hyper-spectral imaging technology designed for long distance explosives and chemical detection.
Devices should be capable of being mobile as the Army intends to mount them on extendable masts on vehicles.

In addition, the sensors must be able to detect explosives with an accuracy of two centimeters on people approaching at twelve miles per hour at a range of 330 feet during daytime, night time, and poor weather situations. The detection system should process data at a mobile workstation in a vehicle. That data would then be streamed via RF data link to a central processing and analysis station. The Army has chosen to pursue hyper-spectral sensor solutions over multi-spectral sensors due to their increased sensitivity and ability to detect more subtle variations. Multi-spectral imagery relies on sensors that measure the amount of reflected energy within a specific set of bands within the electromagnetic spectrum, like visible greens and reds. In contrast, hyper-spectral sensors have the ability to measure reflected energy along a broader number of electromagnetic bands and more sensitive to fluctuations in reflected energy.


1.2 Overview

CGRI 2012-51 project, conducted from June 2011 to May 2012, investigated the disadvantages and hazards of the possible use of quantum cascade lasers (QCL) in long distance explosives detection equipment. Personnel of Kyklotron ltd Detection department participated in the project.


1.3 Purpose

The purpose of this project was to investigate any disadvantages and hazards of using QCLs for long distance explosives detection.


1.4 Objectives

To achieve the purpose, the following objectives were defined:


Investigate the technical readiness of current QCL technologies

Investigate the disadvantages of using QCLs for long distance explosives detection

Investigate the hazards of using QCLs for long distance explosives detection


2. Discussion


2.1 Basics on Raman Spectroscopy

QCL Lasers depending on Raman spectroscopy tech. This is a spectroscopic technique used to study vibrational, rotational, and other low-frequency modes in a system.[1] It relies on inelastic scattering, or Raman scattering, of monochromatic light, usually from a laser in the visible, near infrared, or near ultraviolet range. The laser light interacts with molecular vibrations, phonons or other excitations in the system, resulting in the energy of the laser photons being shifted up or down. The shift in energy gives information about the vibrational modes in the system. Infrared spectroscopy yields similar, but complementary, information. Raman spectroscopy is a spectroscopic technique based on inelastic scattering of monochromatic light, usually from a laser source. Inelastic scattering means that the frequency of photons in monochromatic light changes upon interaction with a sample. Photons of the laser light are absorbed by the sample and then reemitted. Frequency of the reemitted photons is shifted up or down in comparison with original monochromatic frequency, which is called the Raman effect.


Figure 1. Raman spectroscopy system

This shift provides information about vibrational, rotational and other low frequency transitions in molecules. Raman spectroscopy can be used to study solid, liquid and gaseous samples. The Raman effect is based on molecular deformations in electric field E determined by molecular polarizability . The laser beam can be considered as an oscillating electromagnetic wave with electrical vector E. Upon interaction with the sample it induces electric dipole moment P = E which deforms molecules. Because of periodical deformation, molecules start vibrating with characteristic frequency m.

Figure 2. Raman transitional schemes

Amplitude of vibration is called a nuclear displacement. In other words, monochromatic laser light with frequency 0 excites molecules and transforms them into oscillating dipoles. Such oscillating dipoles emit light of three different frequencies (Fig.1) when:

1. A molecule with no Raman-active modes absorbs a photon with the frequency 0. The excited molecule returns back to the same basic vibrational state and emits light with the same frequency 0 as an excitation source. This type if interaction is called an elastic Rayleigh scattering.

2. A photon with frequency 0 is absorbed by Raman-active molecule which at the time of interaction is in the basic vibrational state. Part of the photons energy is transferred to the Raman-active mode with frequency m and the resulting frequency of scattered light is reduced to 0 - m. This Raman frequency is called Stokes frequency, or just Stokes.

3. A photon with frequency 0 is absorbed by a Raman-active molecule, which, at the time of interaction, is already in the excited vibrational state. Excessive energy of excited Ramanactive mode is released, molecule returns to the basic vibrational state and the resulting frequency of scattered light goes up to 0 + m. This Raman frequency is called Anti- Stokes frequency, or just Anti-Stokes.

About 99.999% of all incident photons in spontaneous Raman undergo elastic Rayleigh scattering. This type of signal is useless for practical purposes of molecular characterization. Only about 0.001% of the incident light produces inelastic Raman signal with frequencies 0 m. Spontaneous Raman scattering is very weak and special measures should be taken to distinguish it from the predominant Rayleigh scattering.

Instruments such as notch filters, tunable filters, laser stop apertures, double and triple spectrometric systems are used to reduce Rayleigh scattering and obtain high-quality Raman spectra.

Typically, a sample is illuminated with a laser beam. Light from the illuminated spot is collected with a lens and sent through a monochromator. Wavelengths close to the laser line due to elastic Rayleigh scattering are filtered out while the rest of the collected light is dispersed onto a detector. Spontaneous Raman scattering is typically very weak, and as a result the main difficulty of Raman spectroscopy is separating the weak inelastically scattered light from the intense Rayleigh scattered laser light. Historically, Raman spectrometers used holographic gratings and multiple dispersion stages to achieve a high degree of laser rejection. In the past, photomultipliers were the detectors of choice for dispersive Raman setups, which resulted in long acquisition times. However, modern instrumentation almost universally employs notch or edge filters for laser rejection and spectrographs (either axial transmissive (AT), Czerny-Turner (CT) monochromator, or FT (Fourier transform spectroscopy based), and CCD detectors.

There are a number of advanced types of Raman spectroscopy, including surface-enhanced Raman, resonance Raman, tip-enhanced Raman, polarised Raman, stimulated Raman (analogous to stimulated emission), transmission Raman, spatially offset Raman, and hyper Raman. The Raman effect occurs when light impinges upon a molecule and interacts with the electron cloud and the bonds of that molecule. For the spontaneous Raman effect, which is a form of light scattering, a photon excites the molecule from the ground state to a virtual energy state. When the molecule relaxes it emits a photon and it returns to a different rotational or vibrational state. The Raman effect occurs when light impinges upon a molecule and interacts with the electron cloud and the bonds of that molecule. For the spontaneous Raman effect, which is a form of light scattering, a photon excites the molecule from the ground state to a virtual energy state.


Figure 3. Raman Spectroscopic system

When the molecule relaxes it emits a photon and it returns to a different rotational or vibrational state. The difference in energy between the original state and this new state leads to a shift in the emitted photon's frequency away from the excitation wavelength. The Raman effect, which is a light scattering phenomenon, should not be confused with absorption (as with fluorescence) where the molecule is excited to a discrete (not virtual) energy level.

Figure 4. Raman principal

If the final vibrational state of the molecule is more energetic than the initial state, then the emitted photon will be shifted to a lower frequency in order for the total energy of the system to remain balanced. This shift in frequency is designated as a Stokes shift. If the final vibrational state is less energetic than the initial state, then the emitted photon will be shifted to a higher frequency, and this is designated as an Anti-Stokes shift. Raman scattering is an example of inelastic scattering because of the energy transfer between the photons and the molecules during their interaction.

A change in the molecular polarization potential or amount of deformation of the electron cloud with respect to the vibrational coordinate is required for a molecule to exhibit a Raman effect. The amount of the polarizability change will determine the Raman scattering intensity. The pattern of shifted frequencies is determined by the rotational and vibrational states of the sample.

Figure 5. Energy level diagram showing the states involved in Raman signal. The line thickness is roughly proportional to the signal strength from the different transitions.

Raman scattering or the Raman effect is the inelastic scattering of a photon. It was discovered by Sir Chandrasekhara Venkata Raman and Kariamanickam Srinivasa Krishnan in liquids,[1] and by Grigory Landsberg and Leonid Mandelstam in crystals.

When photons are scattered from an atom or molecule, most photons are elastically scattered (Rayleigh scattering), such that the scattered photons have the same kinetic energy (frequency) and wavelength as the incident photons. However, a small fraction of the scattered photons (approximately 1 in 10 million) is scattered by an excitation, with the scattered photons having a frequency different from, and usually lower than, that of the incident photons.[4] In a gas, Raman scattering can occur with a change in energy of a molecule due to a transition (see energy level). Chemists are concerned primarily with such transitional Raman effect. The inelastic scattering of light was predicted by Adolf Smekal in 1923 (and in German-language literature it may be referred to as the Smekal-Raman effect).



Figure 6. Feynman diagram of scattering between two electrons by emission of a virtual photon

In 1922, Indian physicist C. V. Raman published his work on the "Molecular Diffraction of Light," the first of a series of investigations with his collaborators that ultimately led to his discovery (on 28 February 1928) of the radiation effect that bears his name. The Raman effect was first reported by C. V. Raman and K. S. Krishnan, and independently by Grigory Landsberg and Leonid Mandelstam, in 1928. Raman received the Nobel Prize in 1930 for his work on the scattering of light. In 1998[7] the Raman effect was designated an ACS National Historical Chemical Landmark in recognition of its significance as a tool for analyzing the composition of liquids, gases, and solids.[8]

The Raman effect corresponds, in perturbation theory, to the absorption and subsequent emission of a photon via an intermediate quantum state of a material. The intermediate state can be either a "real", i.e., stationary, state or a virtual state. The Raman interaction leads to two possible outcomes:

  • the material absorbs energy and the emitted photon has a lower energy than the absorbed photon. This outcome is labeled Stokes Raman scattering.
  • the material loses energy and the emitted photon has a higher energy than the absorbed photon. This outcome is labeled anti-Stokes Raman scattering.

The energy difference between the absorbed and emitted photon corresponds to the energy difference between two resonant states of the material and is independent of the absolute energy of the photon. The spectrum of the emitted photons is termed the Raman spectrum, and it is typically displayed according to the energy difference with the absorbed photons. The Stokes and anti-Stokes spectra form a symmetric pattern above and below the absorbed photon energy. The frequency shifts are symmetric because they correspond to the energy difference between the same upper and lower resonant states. The intensities of the pairs of features will typically differ, though. The intensity depends on the population of the initial state of the material. At thermodynamic equilibrium, the upper state will have a lower or equivalent population and the corresponding anti-Stokes spectrum will be less intense.

Figure 7. The different possibilities of visual light scattering: Rayleigh scattering (no exchange of energy so the incident and emitted photons have the same energy), Stokes scattering (the atom or molecule absorbs energy and the emitted photon has less energy than the absorbed photon) and anti-Stokes scattering (the atom or molecule loses energy and the emitted photon has more energy than the absorbed photon)

The Raman effect differs from the process of fluorescence. For the latter, the incident light is completely absorbed and the system is transferred to an excited state from which it can go to various lower states only after a certain resonance lifetime. The result of both processes is in essence the same: A photon with the frequency different from that of the incident photon is produced and the molecule is brought to a higher or lower energy level. But the major difference is that the Raman effect can take place for any frequency of the incident light. In contrast to the fluorescence effect, the Raman effect is therefore not a resonant effect. In practice, this means that a fluorescence peak is anchored at a specific frequency, whereas a Raman peak maintains a constant separation from the excitation frequency.


2.2 Basic Laser - Based Optical Stand-off Spectroscopy


2.2.1 Explosive detection using infrared laser spectroscopy

J. Hildenbrand, J. Herbst, J. Wöllenstein, A. Lambrecht* Fraunhofer Institute for Physical Measurement Techniques (IPM), Heidenhofstr. 8, D-79110 Freiburg, Germany(Invited Paper)



Stand-off and extractive explosive detection methods for short distances are investigated using mid-infrared laser spectroscopy. A quantum cascade laser (QCL) system for TATP-detection by open path absorption spectroscopy in the gas phase was developed. In laboratory measurements a detection limit of 5 ppm*m was achieved. For explosives with lower vapor pressure an extractive hollow fiber based measurement system was investigated. By thermal desorption gaseous TATP or TNT is introduced into a heated fiber.

The small sample volume and a fast gas exchange rate enable fast detection. TNT and TATP detection levels below 100 ng are feasible even in samples with a realistic contaminant background.



The feasibility of standoff and extractive vapor phase explosive detection of TATP and TNT with mid infrared QCL spectroscopy was investigated. A detection limit of 5 ppm*m for TATP was achieved for open path detection in the laboratory. Due to the broad spectral signatures of TATP and TNT scanning across the characteristic absorption lines by tuning of a single laser was not possible. Thus the detection limit is determined by the intensity noise and drift stability of the QCL. We obtained a relative standard deviation of 1.2 * 10-3 over 5 min, depending on laser properties and operation parameters. To increase specificity a second reference laser will be used. In a later stage selectivity can be achieved by using broadly tunable external cavity QCL which recently became commercially available (Daylight Solutions, Inc., Poway, CA, USA). For long distance standoff scenarios the TATP vapour phase concentrations probably are much lower than the currently obtained detection limits of our setup. However by appropriate beam folding e.g. in an optical portal configuration much higher sensitivities can be expected.

If only very small sample amounts are available, which is the case for extractive trace explosive detection, hollow fibers offer a promising solution. TATP and TNT vapor phase detection was demonstrated with a hollow fiber QCL setup.

Detection of a few ng of explosive material within a few seconds is feasible because of the small volume of the hollow fibers. However, dead volumes (desorption chamber, connecting capillaries, fittings, adapters for gas and light coupling at the fiber ends) limit the sensitivity. Summing up to approximately 10 ml in our setup the detection limit was in the 100 ng range.

This situation is similar to (micro-) GC development, where minimization of volumes is essential, too. By microfabrication technology we expect the dead volumes to be reduced below 1 ml, i.e. to the same range as the fiber volume.

A promising concept is the complete integration of a rigid hollow waveguide with connecting micro gas fluidic components into a solid device, e.g. a silicon chip. This would enable ng optical detection and could be hyphenated with other miniaturized analyzers like GC or IMS.


2.2.2 Quantum Cascade Lasers (QCLs) for Standoff Explosives Detection: LDRD 138733 Final Report SANDIA REPORT, SAND2009-6473, Unlimited Release, Printed September 2009Lisa A Theisen and Kevin L Linker



Continued acts of terrorism using explosive materials throughout the world have led to great

interest in explosives detection technology, especially technologies that have a potential for remote or standoff detection. This LDRD was undertaken to investigate the benefit of the possible use of quantum cascade lasers (QCLs) in standoff explosives detection equipment.


Executive Summary

Standoff detection of explosives is currently one of the most difficult problems facing the explosives detection community. Increased domestic and troop security could be achieved through the remote detection of explosives. An effective remote or standoff explosives detection capability would save lives and prevent losses of mission-critical resources by increasing the distance between the explosives and the intended targets and/or security forces. Many sectors of the US government are urgently attempting to obtain useful equipment to deploy to our troops currently serving in hostile environments.

This LDRD was undertaken to investigate the potential benefits of utilizing quantum cascade

lasers (QCLs) in standoff detection systems. This report documents the potential opportunities that Sandia National Laboratories can contribute to the field of QCL development. The following is a list of areas where SNL can contribute:

Determine optimal wavelengths for standoff explosives detection utilizing QCLs

Optimize the photon collection and detection efficiency of a detection system for optical


Develop QCLs with broader wavelength tunability (current technology is a 10% change in

wavelength) while maintaining high efficiency

Perform system engineering in the design of a complete detection system and not just the

laser head

Perform real-world testing with explosive materials with commercial prototype detection



3. A typical Laser-based Stand-off Explosives Detection system in action


Laser-based optical stand-off spectroscopy is not something new. The laser provides a radiation source that interacts with a chemical substance, which in this case is an explosive vapor. The interaction of the radiation and vapor results in an optical signature the can be detected and analyzed using an optical receiver and computational analysis for the spectroscopy.




Figure 8. Phase 1. Laser beam pulse (red line) target the explosive matter




Figure 9. Phase 2. Laser beam pulse hits (5) the explosive matter , producing vapor results (6)





Figure 10. Phase 3. The vapor results (7)




LASER beam absorption heat removal plasma exported






Figure 11. details of the vapor results










Figure 12. Phase 4. Molecules on air (11) around target








Figure 13. Phase 5. A power-laser radiation (7) from a laser source (2) hits molecules, after atmospheric adsorption over explosives (4). The returning light (5) from the explosives Molecules on air (3) inserts into a receiving optics sub system (6) collected the scattered radiation after interaction. A computing unit (1) processing the signals and represent it on a computer screen.






Figure 14. On above figure : a schematic of a QCL system, subsystems, explosive target and molecules representation.


Many factors influence the number of photons that can be ultimately detected, including:


1. The laser power

2. The interaction of the laser radiation and the chemical in question

3. The amount of scattered radiation that can be collected

4. The efficiency of the receiver optics and detector


Although seems to be an easy tech in action, there are factors, as environmental conditions, properties of the chemical substance, and physics that cannot be controlled by technology.


4. QCLs products in determine explosives detection

4.1. ASTAMIDS Fly-By Mine Detectors


IEDs are far and away the greatest threat to our armed forces in Afghanistan, having killed nearly 700 soldiers since 2001 and accounting for roughly half of all US troop deaths in the region since 2008. The newly developed ASTAMIDS system aims to find these booby traps before our ground forces do.

Figure 15. ASTAMIDS, "Airborne Surveillance, Target Acquisition and Minefield Detection System,"

ASTAMIDS, short for "Airborne Surveillance, Target Acquisition and Minefield Detection System," is a state-of-the-art ground-penetrating laser system built by Northrop-Grumman for use aboard the MQ-8 Fire Scout UAV, the UH-60 Blackhawk helicopter, and fixed-wing aircraft. It detects mines ahead of ground forcesday or nightby identifying and classifying thermal and visual anomalies as potential danger areas. The system is capable of quickly identifying the presence of a field and differentiating between surface, buried, and scattered mines.

To accomplish this feat, the 75-pound multi-sensor system relies on multi-spectral imaging using quad-prism aperture-splitting technology assisted by an integrated illuminator, target rangefinder, flight package (GPS, altimeter), and laser designator. It's mounted on an aircraft that flies ahead of advancing forces at a height of 300 feet and at a speed of about 70 knots. The sensor can observe an area 125 feet wide on every pass, and has a two-hour operational capability.

"ASTAMIDS itself is important because of what it will do to alert our ground combat soldiers of approaching threats," said Bob Klein, vice president of Northrop Grumman Maritime and Tactical Systems integrated product team. "What makes this sensor-vehicle combination so significant is that Fire Scout can carry ASTAMIDS far beyond the point of U.S. ground forces to detect the presence of minefields and sight enemy locations without putting a single soldier at risk."

The system's rapid detection capability makes it useful in a variety of situations. Beyond protecting advancing forces, it can also be used during forward recon missions. The system's laser can also designate targets for guided munitions. While ASTAMIDS isn't currently as accurate as ground-based detectors, with upcoming technological improvements the system is expected to be able to operate at higher altitudes in less than ideal conditions and detect a wider array of itemsfrom obstacles to camouflaged vehicles.

The $123 million ASTAMIDS program is still in development, but was successfully tested aboard the Fire Scout back in 2008. Once combat ready, "ASTAMIDS will give Army Brigade Combat Teams unprecedented situational awareness and target designation capabilities," according to the U.S. Army PM Close Combat Systems. Something our forces could sorely use more of. [Murdoc Online - Deagel - IRConnect - Defense Tech - Army Technology ]


4.2 Detecting explosives from a distance with laser beams

Source: http://www.homelandsecuritynewswire.com/dr20120228-detecting-explosives-from-a-distancewith-laser-beams


People like to keep a safe distance from explosive substances, but in order to analyze them, close contact is usually inevitable. At the Vienna University of Technology (TU Vienna), a new method has now been developed to detect chemicals inside a container over a distance of more than a hundred meters. Laser light is scattered in a very specific way by different substances. Using this light, the contents of a nontransparent container can be analyzed without opening it. The method we are using is Ramanspectroscopy, says Professor Bernhard Lendl of TU Vienna. A Vienna University of Technology release reports that the sample is irradiated with a laser beam. When the light is scattered by the molecules of the sample, it can change its energy. For example, the photons can transfer energy to the molecules by exciting molecular vibrations. This changes the wavelength of the light and thus its color.

Analyzing the color spectrum of the scattered light, scientists can determine by what kind of

molecules it must have been scattered. Until now, the sample had to be placed very close to the laser and the light detector for this kind of Raman-spectroscopy, says Bernard Zachhuber. Due to his technological advancements, measurements can now be made over long distances. Among hundreds of millions of photons, only a few trigger a Raman-scattering process in the sample, says Bernhard Zachhuber. These scattered particles of light are scattered uniformly in all directions. Only a tiny fraction travel back to the light detector. From this very weak signal, as much information as possible has to be extracted. This can be done using a highly efficient telescope and extremely sensitive light detectors. In this project, which is funded by the EU, the researchers at TU Vienna collaborated with private companies and with partners in public safety, including The Spanish Guardia Civil who are interested in the new technology.


During the project, the Austrian military was also involved. On their testing grounds the researchers from TU Vienna could put their method to the extreme. They tested frequently used explosives, such as TNT, ANFO, or RDX. The tests were successful: Even at a distance of more than a hundred meters, the substances could be detected reliably, says Engelene Chrysostom of TU Vienna. Raman spectroscopy over long distances even works if the sample is hidden in a nontransparent container. The laser beam is scattered by the container wall, but a small portion of the beam penetrates the box. There, in the sample, it can still excite Ramanscattering processes. The challenge is to distinguish the containers light signal from the sample signal, says Bernhard Lendl. This can be done using a simple geometric trick: The laser beam hits the container on a small, welldefined spot. Therefore, the light signal emitted by the container stems from a very small region. The light which enters the container, on the other hand, is scattered into a much larger region. If the detector telescope is not exactly aimed at the point at which the laser hits the container but at a region just a few centimetres away, the characteristic light signal of the contents can be measured instead of the signal coming from the container. The new method could make security checks at the airport a lot easier but the area of application is much wider. The method could be used wherever it is hard to get close to the subject of investigation. It could be just as useful for studying icebergs as for geological analysis on a Mars mission. In the chemical industry, a broad range of possible applications could be opened up.



4.3 Standoff detection of explosives with external cavity quantum cascade lasers Source: http://spie.org/x85343.xml?highlight=x2412&ArticleID=x85343


There are a number of different security techniques for observing scenes, such as airports, or assessing the safety of inanimate objects, such as suitcases. For example, luggage is typically subjected to x-ray analysis at airports. This type of portal solution requires the cooperation of the owner of the luggage. By contrast, standoff detection can be non-cooperative and carried out by an operator and instrument that are a significant distance from the object under measurement. In the case of explosives detection, this distance is around 525m. For standoff detection of trace amounts of material, only laserbased techniques have the potential to provide sufficient sensitivity.14 Indeed, optical detection techniques based on IR-laser spectroscopy represent a promising approach5, 6 because almost all explosive chemicals typically exhibit strong, characteristic absorbance patterns in the mid-IR spectral range. Transparency of the atmosphere is another crucial prerequisite for detection techniques designed to work over distances of at least a few, preferably some tens of, meters. Thus, the atmospheric transmission window of >7:3m, where (by chance) most organic chemicals exhibit strong light absorbance, is a suitable spectral region for this purpose. Here, we describe the design and assessment of a new mobile imaging standoff detector.

The key element of our system is the quantum cascade laser. These new unipolar semiconductor laser sources are based on intersubband transitions in indium gallium arsenide and aluminum indium arsenide heterostructure superlattices grown on indium phosphide. The gain characteristics of the laser can be optimized for high-power operation as well as for broad spectral tuning. For the present application, it is beneficial to design the quantum well system such that the initial state of the laser transition is a bound state. The broadening of the gain curve is achieved with a superlattice design offering a broadened miniband for the final state. This type of laser design is called bound-tocontinuum.

With these lasers, high power levels that are eye-safe can be generated in the IR spectral region. In the past, semiconductor lasers operating in this spectral range had to be operated using cryogenic cooling. However, new classes of IR lasers are small, rugged, and can operate at room temperature. This makes real-world applications like standoff detection outside a laboratory situation possible. Additionally, quantum cascade lasers are highly wavelength-versatile semiconductor lasers owing to their gain properties, which can easily be tuned over a wide range.7, 8 For spectroscopy of explosives, the range of the laser source needs to cover wavelengths of the fingerprint absorbance of the chemical species being measured.

Within the collaborative Infrared-Laser-based Detection of Explosives project we developed a mobile imaging standoff detection setup that enables detection of explosive traces on surfaces using backscattering laser spectroscopy (see Figure 1). The broadly tunable quantum cascade lasers we used are based on a bound-to-continuum design with a central wavelength of 7.5m. To further increase the spectral range covered by a single chip, we also grew lasers comprising two different active regions with central emission wavelengths of 7.8 and 8.8m, respectively. We refer to this as a heterocascading, or HetCas, design. The gain characteristics of two B-to-C lasers centered at wavelengths of 7.39.5 and 9.5m are combined, resulting in enhanced spectral tuning. This band is ideal for concealed observation because wavelengths of 8m cannot be seen with the naked eye.

Only a person equipped with an IR imager would be able to see that a measurement was being performed. An external cavity quantum cascade laser serves for active illumination with a maximum tuning range of about 300cm−1 (see Figure 2). We used a commercially available IR imager for collecting the diffusely backscattered radiation. Using this setup, we demonstrated the contactless detection of the IR fingerprints of a variety of explosivessuch as pentaerythritol tetranitrate (PETN), trinitrotoluene, and cyclotrimethylenetrinitramineon different substrates, such as pieces of factory-painted sheets from the body of cars as well as the polyamide commonly used in backpacks. The software processing of the hyperspectral datacube enables fully automatized identification against a background of nonhazardous materials.

The sensitivity depends both on laser performance and the sensitivity of the IR imager. With an uncooled bolometric IR camera, our system shows reliable detection at a distance of 35m. PETN-contaminated handprint on painted autobody sheet after active laser illumination at a

distance of 3m. The difference of images taken with laser radiation at 1286 and 1296cm−1 from the raw images in a first step provides a very specific signature for PETN. More sophisticated signal processing, including image analysis, enhances the quality of the discrimination against other materials. Using a high-end IR imager operating at 77K, we could demonstrate identification of traces of PETN up to 20m.

In summary, we have designed a new standoff IR device for detecting organic molecules such as explosives using quantum cascading laser sources. The concept we have demonstrated offers high potential for miniaturization. The next-generation instruments will be hand-held and battery operated.

Currently, we use commercially available IR cameras for detecting backscattered laser radiation. With IR detection systems optimized for the special case of active laser illumination, a significant further increase of sensitivity is expected.


5. Could QCLs detect explosives in long range ?


LASER beam only works straight from the target. Due to the curvature of the earth's surface targeting of objectives can not be done over real long distances.


6. Could QCLs detect explosives when a parapet is in front of them ?


To detect explosive matters from long distance, should be a visible target. The QCLs beam could not pass through an obstacle in front of the IDE or explosive.In conclusion, the user can not investigate explosives behind any parapet (walls, metal curtain, mountains, hills, etc.) especially in long distance.


6.1 Reflection and Absorption of Laser Beams


If the surface being machined reflects too much light energy, the absorbed energy is decreased, the operation efficiency is lowered, and the reflected light may do harm to the optical systems. So reflection and absorption of laser beams is closely related to laser machining.

The value of absorption and reflection is related by:

Reflectivity = 1- Absorptivity (for opaque materials) or

Reflectivity = 1- Absorptivity - Transmissivity (for transparent materials)



Figure 16. Light transmission in medium

The reflection coefficient R for normal angles of incidence from air to opaque perfect flat clean metal surface can be computed using the following formula:


and the absorptivity A of opaque metal surface is:

A= 1 R =4n/[(n+1)2+k2]

Where n is the refraction coefficient of material, k is the extinction coefficient of material. Both value can be looked up in handbooks. We list some of the values in the following table. Remember these optical properties are functions of radiation wavelength and varies with temperature.

Table 1 : Some material's optical properties (under 1.06 micro radiation)

















































 Next we examine the factors that affect reflectivity and absorptivity.

Wavelength: the shorter the wavelength, the more energetic the photons are. Photons with shorter wavelengths are easier to be absorbed by the materials than photons with longer wavelengths. Thus R normally decreases as wavelength becomes shorter, while absorption increases when photon energy increases.

Temperature: as temperature rises, there will be an increase in the phonon population. Electrons are more likely to interact with the structure rather than with the incident photons. So there is a fall in the reflectivity and an increase in the absorptivity with a rise in temperature.

Angle of Incidence and Plane of Polarization: reflectivity varies with both the angle of incidence and plane of polarization. If the plane of polarization is in the plane of incidence, the ray is called parallel ray ("p" ray); if the plane of polarization is perpendicular to the plane of incidence, the ray is called "s" ray. The reflectivity coefficients for perfect flat surfaces of the "p" ray and "s" ray are:

Rp=[(n-1/cosf )2+k2] / [(n+1/cosf )2+k2]

Rs=[(n-cosf )2+k2] / [(n+cosf )2+k2]

Where f is the incident angle, n is the refraction coefficient, k is the material extinction coefficient. We see here the reflectivities of p ray and s ray are different, p rays are more easily absorbed by materials than s rays do. You can try the following animation to see the difference.

6.2 Materials resistant to radiation and beam impact


Present status of study on development of materials resistant to radiation and beam impact

M. Kawai a, H. Kokawa b, M. Michiuchi b, H. Kurisihita c, T. Goto d, M. Futakawa e, T. Yoshiie f, A. Hasegawa b,S. Watanabe g, T. Yamamura b, N. Hara b, A. Kawasaki b, K. Kikuchi e Journal of Nuclear Materials 377 (2008) 2127


A b s t r a c t

Pulsed spallation neutron sources for the materials structure science are severely influenced by beam impact and radiation damage. We have developed the materials strong to these influence since 2004. In this paper, recent topics are described concerning the development of intergranular corrosion (IGC)- resistant austenitic stainless steel for target vessel and window, radiation-resistant ultra-fine grained tungsten materials (WTiC) for a solid target, CrN film on a tungsten target by means of a molten-salt method, surface treatment of stainless steel for pitting damage in mercury target. Bubble behavior at the interface of mercury and window glass was also observed to clarify the phenomenon of the pitting damage.


6.3      Fullerene films highly resistant to laser radiation

M. A. Khodorkovskii, S. V. Murashov, T. O. Artamonova, A. L. Shakhmin, A. A. Belyaeva and V. Yu. Davydov

The effect of laser radiation on the structure and phase composition of thin fullerene films is studied. Raman measurements show that fullerene films applied with a supersonic molecular beam remain structurally stable even if the laser power density is many hundreds of times higher than that at which thermally deposited films degrade. A plausible reason for a high laser radiation hardness of the films is fast polymerization with the formation of linear and multidimensional configurations.



7. Could QCLs tech interfered and how ?


7.1 Common optical CDs and DVD s disks LASER beam absorning


LASER beams are absorbed by appropriate chemical and other substances that are easy and cheap to acquire them, as for example the common optical disc recording and reproducing digital (Compact Disks DVDs ).


If we put a Compact Disk over or in front of the target (explosive matter) it is possible that this optical disk could absorb the LASER beam and is a strong opportunity that user missed the target. In case of an IDE in the side of the road it is very possible that this explosive could blast and destroy the vehicle, the detection system and the crew.


The same incident had been take place when the first LASER car speed detectors used from road police in Europe and USA. Every driver had hang an optical disk (CD) on the central mirror installed on the front glass of the car. The optical CD absorbed the LASER beam from the police car speed detector. Before this drivers driving fast had to spend a lot of money for buying anti-radar (radio wave tech ) to undertake police radio waves car speed radars.



Figure 17. A Compact Disk (CD) icon and a digital representation









Figure 18. CD details in how it works









Figure 19. CD , the burning surface that absorbs LASER beams




7.2    LASER beam can be bounced off of mirrors


Unlike other types of commercial available light sources, a laser beam can be bounced off of almost any number of mirrors and retain its visual strength. With a little practice and enough shiny surfaces, you can reflect a laser beam across the entirety of your home and still hit a target the size of a pinhead.

7.2.1 Using Just simple MIRRORS !!!



Figure 20. Common mirror , like those on common cars front glasses.


Common mirrors reflects LASER beams




7.2.2 LASER beam can be bounced off of Crystals



Figure 21. Crystal and laser beam bounced off




Figure 22. Prismatic Crystal and laser beam bounced off


Some kind of crystals reflects LASER beams






Source: http://www.lbp.co.uk/Materials/Copper.html?gclid=CNDDovyi3K8CFQMx3wodCwNL_Q




Figure 23 Cooper type LASER reflectors


CO2 lasers rely on Copper mirrors as beam delivery optics for laser cutting, laser engraving, and laser welding. Other applications use infrared mirrors, and copper mirrors are the most common laser mirror for high energy or broadband infrared applications. High thermal conductivity, high heat capacity, and when freshly polished, uncoated Copper mirror surfaces have a high natural reflectivity for infra red too.

Because polished copper reflector surfaces react with the atmosphere and lose reflectivity, most, but not all cavity mirrors and beam delivery mirrors, are generally used with a coating, to improve reflectivity, durability, or alter polarisation on reflection. There are several metal mirror optical coatings as , Electroplated Gold coated Copper mirrors ,

MaxR zero phase shift Copper mirrors for CO2 laser , L/4 reflective phase retarder mirror for CO2 laser , Protected silver coating for broad infrared reflectivity.

To improve the laser damage resistance, and reduce scatter, Copper mirrors have a thin intermediate layer of electroless nickel deposited. This gives an amorphous, non crystalline, surface of exceptional smoothness. Electroless Nickel plating also protects the whole of the mirror from oxidation, and prevents contamination of, or reaction with, the lasing gas, such as in sealed slab discharge resonators.

Laser Beam Products' Copper mirrors are chemically polished, the surfaces are super smooth, and are free of imperfections from turning lines, fly cutting arcs, and diffractive patterns that are common on diamond turned optics. This gives a high laser induced damage resistance, & a super-smooth, low scatter mirror surface.

Finally, our proprietary stress relieving and heat treatment, gives long term stability and performance, across a wide range of operating temperatures.

For the highest laser powers, and for maximum stability, internal water cooling channels can be machined into the Copper mirror itself.

As Copper is readily machinable, we offer a huge range of mirror shapes and sizes, such as prisms, axicons, rectangular or square mirrors, chopper wheels, knife edge mirrors and shutter mirrors. By engineering in features such as dowel holes, tapped and helicoiled holes, or flanges, a well designed copper mirror can save costs in mounting, assembly, and laser alignment.      


Laser Beam Products stock a wide range of Copper mirrors with a selection of mirror coatings that are standard replacement parts for the most popular CO2 laser cutting systems.

Meeting or exceeding the OEM standards, these also cost less, as we are an optical manufacturer. We stock Copper mirrors for most European, US, and Japanese laser cutting & laser engraving systems.

Used CO2 laser optics are generally reworkable to as good as new condition. The raw metal material in larger mirrors, water cooled mirrors, or laser mirrors with complex engineering can be a large part of the cost of the optic, so refurbishment makes economic, technical, and environmental sense contributing to ISO 14000. Newsletter about reworking used CO2 laser mirrors .



7.3 Air vacuum and Spreadable molecules


Spreadable molecules existing in some distance on air away from the actual explosive matter does not exist in a vacuum air. In this case if the explosive placed in an air vacuum system with no particles scattered outside of the explosive mass, could no be detected by systems using the spectrometer Raman tech .

7.3.1. What is vacuum ?

Vacuum is space that is empty of matter. The word stems from the Latin adjective vacuus for "empty". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressure.[1] Physicists often discuss ideal test results that would occur in a perfect vacuum, which they sometimes simply call "vacuum" or free space, and use the term partial vacuum to refer to an actual imperfect vacuum as one might have in a laboratory or in space. The Latin term in vacuo is used to describe an object as being in what would otherwise be a vacuum.

The quality of a partial vacuum refers to how closely it approaches a perfect vacuum. Other things equal, lower gas pressure means higher-quality vacuum. For example, a typical vacuum cleaner produces enough suction to reduce air pressure by around 20%.[2] Much higher-quality vacuums are possible. Ultra-high vacuum chambers, common in chemistry, physics, and engineering, operate below one trillionth (10−12) of atmospheric pressure (100 nPa), and can reach around 100 particles/cm3.[3] Outer space is an even higher-quality vacuum, with the equivalent of just a few hydrogen atoms per cubic meter on average.[4] However, even if every single atom and particle could be removed from a volume, it would still not be "empty" due to vacuum fluctuations, dark energy, and other phenomena in quantum physics. In modern Particle Physics, the vacuum state is considered as the ground state of matter.

Vacuum has been a frequent topic of philosophical debate since ancient Greek times, but was not studied empirically until the 17th century. Evangelista Torricelli produced the first laboratory vacuum in 1643, and other experimental techniques were developed as a result of his theories of atmospheric pressure. A torricellian vacuum is created by filling with mercury a tall glass container closed at one end and then inverting the container into a bowl to contain the mercury.[5]

Vacuum became a valuable industrial tool in the 20th century with the introduction of incandescent light bulbs and vacuum tubes, and a wide array of vacuum technology has since become available. The recent development of human spaceflight has raised interest in the impact of vacuum on human health, and on life forms in general.


7.3.2 How to create vacuum


A vacuum pump is a device that removes gas molecules from a sealed volume in order to leave behind a partial vacuum. The first vacuum pump was invented in 1650 by Otto von Guericke, and was preceded by the suction pump, which dates to antiquity.

Pumps can be broadly categorized according to three techniques:[1]

  • Positive displacement pumps use a mechanism to repeatedly expand a cavity, allow gases to flow in from the chamber, seal off the cavity, and exhaust it to the atmosphere.
  • Momentum transfer pumps, also called molecular pumps, use high speed jets of dense fluid or high speed rotating blades to knock gas molecules out of the chamber.
  • Entrapment pumps capture gases in a solid or adsorbed state. This includes cryopumps, getters, and ion pumps.

Positive displacement pumps are the most effective for low vacuums. Momentum transfer pumps in conjunction with one or two positive displacement pumps are the most common configuration used to achieve high vacuums. In this configuration the positive displacement pump serves two purposes. First it obtains a rough vacuum in the vessel being evacuated before the momentum transfer pump can be used to obtain the high vacuum, as momentum transfer pumps cannot start pumping at atmospheric pressures. Second the positive displacement pump backs up the momentum transfer pump by evacuating to low vacuum the accumulation of displaced molecules in the high vacuum pump. Entrapment pumps can be added to reach ultrahigh vacuums, but they require periodic regeneration of the surfaces that trap air molecules or ions.

Figure 24 how pump works

Due to this requirement their available operational time can be unacceptably short in low and high vacuums, thus limiting their use to ultrahigh vacuums. Pumps also differ in details like manufacturing tolerances, sealing material, pressure, flow, admission or no admission of oil vapor, service intervals, reliability, tolerance to dust, tolerance to chemicals, tolerance to liquids and vibration.

Fluids cannot be pulled, so it is technically impossible to create a vacuum by suction. Suction is the movement of fluids into a vacuum under the effect of a higher external pressure, but the vacuum has to be created first. The easiest way to create an artificial vacuum is to expand the volume of a container. For example, the diaphragm muscle expands the chest cavity, which causes the volume of the lungs to increase. This expansion reduces the pressure and creates a partial vacuum, which is soon filled by air pushed in by atmospheric pressure.

To continue evacuating a chamber indefinitely without requiring infinite growth, a compartment of the vacuum can be repeatedly closed off, exhausted, and expanded again. This is the principle behind positive displacement pumps, like the manual water pump for example. Inside the pump, a mechanism expands a small sealed cavity to create a deep vacuum. Because of the pressure differential, some fluid from the chamber (or the well, in our example) is pushed into the pump's small cavity. The pump's cavity is then sealed from the chamber, opened to the atmosphere, and squeezed back to a minute size.

More sophisticated systems are used for most industrial applications, but the basic principle of cyclic volume removal is the same:


Figure 25 inside a pump

Rotary vane pump, the most common

The base pressure of a rubber- and plastic-sealed piston pump system is typically 1 to 50 kPa, while a scroll pump might reach 10 Pa (when new) and a rotary vane oil pump with a clean and empty metallic chamber can easily achieve 0.1 Pa.

A positive displacement vacuum pump moves the same volume of gas with each cycle, so its pumping speed is constant unless it is overcome by backstreaming.

Figure 26. vacuum pump Figure 27. A cutaway view of a turbomolecular high vacuum pump

In a momentum transfer pump, gas molecules are accelerated from the vacuum side to the exhaust side (which is usually maintained at a reduced pressure by a positive displacement pump). Momentum transfer pumping is only possible below pressures of about 0.1 kPa. Matter flows differently at different pressures based on the laws of fluid dynamics. At atmospheric pressure and mild vacuums, molecules interact with each other and push on their neighboring molecules in what is known as viscous flow. When the distance between the molecules increases, the molecules interact with the walls of the chamber more often than the other molecules, and molecular pumping becomes more effective than positive displacement pumping. This regime is generally called high vacuum.

Molecular pumps sweep out a larger area than mechanical pumps, and do so more frequently, making them capable of much higher pumping speeds. They do this at the expense of the seal between the vacuum and their exhaust. Since there is no seal, a small pressure at the exhaust can easily cause backstreaming through the pump; this is called stall. In high vacuum, however, pressure gradients have little effect on fluid flows, and molecular pumps can attain their full potential.

The two main types of molecular pumps are the diffusion pump and the turbomolecular pump. Both types of pumps blow out gas molecules that diffuse into the pump by imparting momentum to the gas molecules. Diffusion pumps blow out gas molecules with jets of oil or mercury, while turbomolecular pumps use high speed fans to push the gas. Both of these pumps will stall and fail to pump if exhausted directly to atmospheric pressure, so they must be exhausted to a lower grade vacuum created by a mechanical pump.

As with positive displacement pumps, the base pressure will be reached when leakage, outgassing, and backstreaming equal the pump speed, but now minimizing leakage and outgassing to a level comparable to backstreaming becomes much more difficult. Claw type vacuum pumps are suitable for applications requiring pressure, vacuum or pressure/vacuum simultaneously.

Vacuum up to 150 mbar (abs) and capacities from 100 to 600 m/hr

Pressure up to 2.2 bar and flow rates from 100 to 600 m/hr

In combined operation, vacuum up to -0.6 bar and pressure up to 1.0 bar can be achieved simultaneously.


The Claw Principle


Figure 28 The Rietschle claw pump The Claw Principle

The Rietschle claw pump consists of two rotors (1, 2) which rotate in opposite directions without contact, synchronised by precision oil lubricated gears. Air is drawn in at the suction port (4), compressed and exhausted at the discharge port (5).

The internal compression gives much higher efficiency than roots blowers, dry vane compressor and even dry screw compressors. A cooling fan directs air between the outer cover (10) and finned housing. This design is characterised by high efficiency oil free compression, low noise levels and very low maintenance requirements. Vacuum food saver boxes as an anti-LASER detector solution


When foods are exposed to the air, they quickly deteriorate affecting taste, flavour and crispness. The Vacuum Food Savers prevent this keeping them as fresh and dry as the day they were first opened. The vacuum pump simply extracts the air from the container creating a vacuum and keeping 'air sensitive' foods such as biscuits, cookies, crisps, nuts and cereals in perfect condition. There are several sizes of containers which are stackable and dishwasher safe.

Those plastic cans could used as nests for explosives. Extracting the air from the container we creating a vacuum, so the molecules of the explosive matter could not be detected from QCLs detectors. Vacuum Pump for laboratories

Vacuum pumps are widely used in scientific laboratories on a variety of scientific instruments including mass spectrometers, electron microscopes and many other instruments. These pumps can be a major source of laboratory air contamination. Indoor air contamination by vacuum pumps originates from both the lubricating oils used in the pumps, and also from chemicals that have contaminated the pump oil. When the vacuum pumps are used in instruments such as mass spectrometers, all the residual organics analyzed by the mass spectrometer are trapped in the vacuum pump oil. Eventually these organics are purged out of the oil and into the laboratory air via the vacuum pump exhaust port. Often the organic chemicals analyzed by these vacuum system instruments can be quite toxic or carcinogenic. This can present a serious environmental health problem in the laboratory. These pumps can be a major source of indoor contamination and therefore it is normally recommended that these pumps be vented outside the room or to a laboratory exhaust hood. However this is not always practical when the instrumentation is located within the interior of a building.

Figure 29. A typical vacuum pump for laboratories

This is the third part of three articles reporting on the effectiveness of filters designed for use on the exhaust ports of vacuum pumps (1, 2 & 3). The previous article in this series (2) demonstrated that oil mist eliminators were effective at trapping the heavy oils from the vacuum pumps, but they were ineffective at trapping the more volatile organics from the vacuum pumps. This article discusses the effectiveness of the charcoal trap as a vacuum pump exhaust trap to solve this problem of trapping the more volatile organics in vacuum pump exhaust. The charcoal trap provides minimal backpressure to the vacuum pump exhaust and its large volume of trapping efficiency can solve most laboratory vacuum pump emission problems. When the charcoal trap is used in series with the oil mist eliminator, a very effective system is achieved which can trap the emissions from vacuum pumps and improve the quality of air in the instrument laboratory (1). VACUVIN - Vacuum food saver boxes

When foods are exposed to the air, they quickly deteriorate affecting taste, flavour and crispness. The Vacuum Food Savers prevent this keeping them as fresh and dry as the day they were first opened. The vacuum pump simply extracts the air from the container creating a vacuum and keeping 'air sensitive' foods such as biscuits, cookies, crisps, nuts and cereals in perfect condition. There are several sizes of containers which are stackable and dishwasher safe.


This is a chip and easy idea: to enclose explosives in vacuum food saver box.


VACUVIN - Vacuum food saver boxes


Figure 30. Vacuum food saver boxes Pump engineered for make vacuum in containers.

Tecla Gastrovac is a pump engineered for make vacuum in containers.It is equipped with a stainless steel body, an high precision vacuum gauge with hand and a very robust and high performance pump.This vacuum machine is suitable for catering operators and restaurants.

Figure 31 Pump engineered for make vacuum in containers

It allows, in combination with Tecla Gastronorm GM vacuum containers Vacuum Boxes, packaging directly into Gastronorm GM boxes all the products that cannot be crushed, so they would limit strongly the use of traditional vacuum preservation. Attention paid by Tecla in mounting and engineering processes, with superb quality of materials and parts, give to this product an high reliability and a long life.


7.4      Anti LASER systems. A LASER SHIELD for LASER beams.

Yidong Chong/Yale University

The device, which the scientists call a coherent perfect absorber or, more popularly, an anti-laser, may lead to the development of new kinds of switches, filters and other components that could be useful in hybrid optical-electronic computers under development, among other applications.

A. Douglas Stone, a theoretical physicist at Yale, developed the concept of a backward-running laser in a paper in Physical Review Letters last spring. The actual device, described in a paper published last week in Science, was created in the laboratory of a laser physicist, Hui Cao. In a laser, energy is pumped into a medium which can be a solid, liquid or gas between two mirrors, stimulating the emission of photons that are coherent, or of the same frequency and phase. The photons reflect back and forth between the mirrors, resulting in amplification of the light.

You put energy into it, and some of that energy gets converted into that beautiful coherent light beam, Dr. Stone said. In his theoretical work, Dr. Stone said, he made use of the fact that the equations that describe how a laser works have certain symmetrical properties.

If you can make a laser of a certain type, the equations say you can make a reverse device as well, he said.

An anti-laser uses mirrors, too, but the other components are the reverse of a laser. The medium that provides amplification is replaced with one that provides absorption, and the outgoing light beam is replaced with an incoming one. (This light needs to be coherent, so it takes a laser to make an anti-laser.)

The incoming beam is split in two, and hits the medium from two sides. The photons bounce around between the mirrors and interfere with one another, eventually wiping themselves out in a flurry of electrons and heat. The experimental device absorbed about 99.4 percent of the light. In theory, an anti-laser should be able to absorb 100 percent. Its a one-way trap for light, Dr. Stone said. Dr. Cao said the device they built was relatively simple, using silicon as the absorptive medium and a couple of bad mirrors.



Figure 32. A LASER SHIELD for LASER beams.

But we should be able to get coherent perfect absorption in more complicated systems, she said. Eventually it may even be possible to make an anti version of a so-called random laser, in which the medium is highly disordered and there are no mirrors.

The experimental device works in the near-infrared, outside of the visible spectrum. But Dr. Stone said that in principle anti-lasers would not be limited in terms of frequency.

We could move it into the visible, or the farther infrared, he said. Its definitely possible to engineer this across the whole range.

Stefano Longhi, a physicist at the Polytechnic Institute of Milan in Italy who was not involved in the work, said the anti-laser was an important achievement that was exciting and surprising to the scientific community.

He said one important characteristic of the device is that the absorption could be turned on or off. This might make anti-lasers extremely useful as optical switching devices.

A device that absorbs light perfectly might be considered ideal for solar energy applications, but Dr. Longhi said this is not the case. Sunlight is not coherent, and an anti-laser will not work with incoherent light, he said.

A physicist would describe the device as a time-reversed laser, since the symmetrical properties are related to the concept of time reversal.

But Dr. Stone said he thought the term anti-laser was a better description for nonscientists, so that no one would think the device had anything to do with time travel.

But even anti-laser is problematic, he noted. I dont want people to think this is some kind of laser shield, he said. If R2-D2 had our anti-lasers, it would be melted into a puddle.


7.5      Pyrotechnic composition for producing radiation-blocking screen


Patent No: 4728375 Inventor: Simpson Date Issued: March 1, 1988 Application: 06/639,685 Filed: April 4, 1984 Inventors: Simpson; Geoffrey M. (Nottingham, GB)
Haley & Weller Limited (Draycott, GB) Primary Examiner: Lechert, Jr.; Stephen J. Assistant Examiner: Attorney Or Agent: Hinds; William R. U.S. Class: 102/505; 149/21; 149/29; 149/4; 149/5; 149/72; 149/73 Field Of Search: 149/29; 149/4; 149/5; 149/61; 149/72; 149/73; 149/21; 102/505 International Class: U.S Patent Documents: 2574466; 3657027; 4151233; 4503004


A pyrotechnic composition for producing a screen for blocking the passage of infra-red radiation and of light, comprises phosphorus, preferably red amorphous phosphorus, dispersed in a binding agent, for example rubber. The composition is produced by forming the binding agent into a gel with solvent, dispersing the phosphorus into the gel, evaporating off solvent, and comminuting the resulting solid material. This invention relates to a pyrotechnic composition for producing a radiation-blocking screen, and to a method of manufacturing such a composition.

Smokes have been used to produce screens to prevent visual detection of mobile objects such as vehicles or ships. Increasing use is now made, however, of devices which can detect emissions of infra-red radiation from relatively hot parts ofvehicles, such as the engines. These devices may render the vehicle vulnerable to attack by the use of infra-red sensitive sights in conjunction with conventionally-aimed weapons, or by the use of so-called heat-seeking projectiles or missiles. The invention provides a pyrotechnic composition whose use can provide a screen capable of blocking the operation of infra-red detectors operating at wavelengths in the range of 10-14 .mu.m, such wavelengths often being able to penetrateconventional smokes.

According to the invention, there is provided a pyrotechnic composition which, when ignited, exposively produces an infrared radiation blocking screen for an intended target, the pyrotechnic composition comprising a phosphorus and other combinedcomponents of composition, form and size as to produce an infrared radiation blocking screen operating in a first and a second mode, the first mode being provided substantially instantaneously following the explosion of the composition and comprising acloud of high temperature gas and particles producing a broad infrared target masking the intended target, and the second mode being provided immediately following the first mode and comprising a cloud of radiation absorbent particles dispersed withinthe cloud to provide a large infrared absorbent area to mask the intended target for a further period.

Preferably the composition comprises a red amorphous allotropic phosphorous dispersed in a binding agent. The combustion of the red amorphous allotropic phosphorous provides the first mode, and the dispersion of the binding agent caused by thecombustion of the red amorphous allotropic phosphorous causes the second mode.

Preferably the composition contains about 95% by weight of phosphorus. The composition is preferably in granular form, more preferably with the particles just passing an 8 mesh screen (i.e. having a maximum particle size of about 3.2 mm). Withlarger particle sizes, there is an increasing tendency for burning granules to fall to the ground, decreasing the effectiveness of the screening. Smaller particle sizes present handling difficulties.

The binding agent is suitably a rubber, such as a styrene-butadiene rubber, preferably including a carbon filler, up to 9% by weight of the rubber being a suitable proportion.

It is desirable to dust the granules with a fine powder to ensure their separation and uniform dispersion in use, and a suitable material for this is a sulphurless milled powder (SMP), being a sulphur-free gunpowder. The powder suitably forms 1to 2% of the weight of the granules after dusting.

The invention also provides a method of manufacturing a pyrotechnic composition for producing a radiation-blocking screen, comprising forming a gel of the binding agent in a solvent, dispersing phosphorus, preferably red amorphous phosphorus,into the gel, evaporating off the solvent, and comminuting the resulting material.

It has been found that compositions in accordance with the invention can produce effective infra-red and visible light blocking for a period in excess of 30 seconds. Initially, the heat produced by the combustion of the phosphorus causes arelatively uniform emission of infra-rad radiation across the area over which the composition is distributed. This renders detection of emissions from behind the resulting cloud very difficult or impossible. When the cloud cools, an aerosol ofinfra-red absorbing and/or reflecting particles is left which prevents the transmission of infra-red radiation to the detector. The cloud produced is stable and is less affected by weather conditions than smokes resulting solely from the combustion ofcarbon-containing compounds.

The pyrotechnic composition of the invention can be used in any of the devices, such as grenades, in which known pyrotechnic compositions are used. If necessary, gunpowder or the like may be mixed with the composition to ensure wide distributionof the screen on ignition. For the production of a large screen, a plurality of charges of the composition may be dispersed and then ignited.

The following Example illustrates a pyrotechnic composition according to the invention.

A pyrotechnic composition was prepared by dissolving in dichloromethane a carbon-containing styrene-butadiene rubber (INCARB 5609, sold by International Synthetic Rubber Company Limited). Red amorphous phosphorus in powder form was dispersedinto the resulting gel and the solvent was then evaporated off to leave a solid mass. The solid mass was comminuted to pass an 8 mesh screen. The resulting mixture contained, by weight, 95% of phosphorus. The rubber contained 9% by weight of carbonblack. The composition granules resulting from comminution were dusted with sulphurless milled powder having a grain size similar to flour, and then packed into a container with an explosive charge dispersed through the composition. A conventionalignition charge and fuze were incorporated.

On detonation of the resulting device at a position between an infra-red source and an infra-red radiation detector, a dense cloud of smoke was produced dispersed upwardly and outwardly of the device, the cloud itself initially producinginfra-red radiation which completely masked the radiation from the source, preventing its detection by the detector. As the cloud cooled, it served to block the passage of radiation from the source to the detector. The total time for which the cloudwas effective in blocking detection of radiation from the source was in excess of 30 seconds. It was also observed that the cloud was impenetrable by laser beams. The cloud would therefore provide effective blocking of the operation of laser-quidedprojectiles and missiles, and laser range-finding devices.


7.6 Large, single-domain crystals of KTA and RTA commercially available.

Large, single domain crystals of KTA and RTA are now commercially available for nonlinear optical and electrooptic device applications.  Development of CTA is in progress and crystals are available on a R&D basis. These materials feature large nonlinear optical and electrooptic coefficients, and have significantly reduced absorption in the 3-5 mm region as compared to KTP. The large nonlinear coefficients are combined with broad angular and temperature bandwidths. Additional advantages of the arsenates are low dielectric constants, low loss tangent and ionic conductivities orders of magnitude less than KTP. Single crystals of these arsenates are chemically and thermally stable, nonhygroscopic and highly resistant to high intensity laser radiation. http://www.coherent.com


7.7 Coherent perfect absorbers (CPA) Anti-lasers spawn

At the beginning of the year, I attended a conference called Physics of Quantum Electronics, where I learned about something called coherent perfect absorbers (CPA). At the time, I didnt write about it because I couldnt decide if I understood it or notI felt as if I should, but I thought the presenters were trying to make a different point from the one I took home. Fast forward a few months, and CPA turns up in Science (and at Ars, even though I didnt cover it). The paper became the subject of intense scrutiny in my research group. And, even better, one of the key authors visited us, and my boss had a good chat with her about it as well.

The upshot is that now, when a new take on CPA appeared in Physical Review Letters, I was prepared to take the subject on at last.

The main reason I shied away from CPA in the past was that it looked achingly familiar. But I couldnt put a name to it, and I didnt put the time into figuring out what it reminded me of. Then, in our journal club, the presenter used a set of words that every electrical engineer in the world will recognize: impedance matching. Thats the task of crafting the interface between two materials so that electromagnetic waves can traverse it without creating interference from waves that are reflected by the interface.

People dont always recognize that impedance matching is also a requirement for optics. In this case, I am not talking about anti-reflection coatings, but rather getting light into an optical cavitythough the two are not all that different from each other.

To understand this in terms of optics, we need to take a closer look at what an optical cavity is. Take two mirrors with reflectivities of 99.99 percent. These mirrors should be curved, and to make things simple, we will place them facing each other so that they have a common focal point between them. A cavity is formed when light travels from one mirror surface to the other and back again and finds that its spatial field distribution is unchanged. If that is true at one mirror surface, it will be true everywhere between the two mirrorsthe spatial pattern varies along the length between the two mirrors, but not in time. 

In other words, you cannot tell from the lights field distribution how many round trips it has made. This spatial distribution is called the spatial mode of the cavity, and we will return to it shortly.

You might think that having mirror reflectivities of 99.99 percent would make it difficult to get light into the cavity. Certainly, if I put a piece of paper between the mirrors (so the optical cavity is broken) and then shine a laser on each mirror, 99.99 percent of the light will come bouncing back. But if I unblock the cavity and just shine light on one mirror, the amount of light reflected will change. It might be all, or none, or anywhere in between.

This is because all light is in a mode, and most light sources emit into many different modes. When we shine light in an uncontrolled manner on the front mirror of the cavity, the fraction of the light that is in the same mode as the optical cavity will be entirely transmitted. If I use a laser that emits light into a single spatial mode and the correct set of lenses, I can ensure that all the light falling on the front mirror is in the mode of the cavity. In this case, all the light will be transmitted. This is called mode matching in optics, and impedance matching by electrical engineers.



Figure 33. A domestic SHIELD for LASER beams.

More precisely, the light returning from the back mirror is exactly out of phase with light that would be reflected from the front mirror. The resulting interference between the light trying to leave the cavity from the front mirror and light reflected from the front mirror (which has never entered the cavity), is destructive, leaving no reflected light.

So our mirrors arent reflecting, and the light beam acts as if the cavity isnt there at all. If we add a little bit of absorption to the cavity, we lose that nice balance. Not all the light is transmitted by the cavity, and because the light bouncing around in the cavity is being absorbed, it doesnt have sufficient intensity to cancel out the reflected beam.

Making a coherent perfect absorber involves adding a second laser beam that enters from the back face of the mirror. Now, the light that enters the cavity from the opposite direction can balance the absorption of the first laser beam. In doing so, it eliminates the reflection from the front mirror. This requires carefully tuning the laser beams phase and amplitude with respect to the laser entering from the front mirror. When you satisfy this condition, you also satisfy the condition required for the light reflected from the back mirror by the second laser to be cancelled as well.

The end result is that lots of light enters the optical cavity and none leaves. Its called coherent because it requires that the laser beams maintain a particular relationship to one another, otherwise the absorption is not perfect. But this is just classical interference, and as the engineers will tell you, impedance matching is impedance matching, no matter how you do it.

A device that is very close to my heart is called an optical parametric oscillator. In this device, you have an optical cavity with a crystal between the mirrors. We send a laser beam into the optical cavity, and when the light intensity is high enough, the crystal will split photons from the laser light field into two lower energy (longer wavelength) photons. Allowing these to resonate in the cavity results in a relatively efficient conversion process, taking one coherent light source and outputting two coherent light sources with the wavelength of your choiceTM.

This looks a bit like absorption as far as the laser beam you put into the cavity is concerned. We put the light in and it vanishedlooks like absorption to me. But it also looks like an amplifier (thats what the A in laser stands for) since we are getting light fields out that we never put in. The question, then, is what would CPA look like for an optical parametric oscillator?

Stefano Longhi from Milano set out to answer this question. He considered a fairly standard model of an optical parametric oscillator with one exception: the two generated light waves, called signal and idler, travel in opposite directions. Then he balanced these with input beams, to totally destroy the signal and idler, leaving the original laser beam looking as if nothing had ever happened.

In this case, the process is a little more complicated, but it basically depends on the fact that physics doesnt generally care about time directionality. In other words, the process of splitting one high energy photon into two low energy photons is exactly equivalent to combining two low energy photons into a single high energy photon. In that case, how does nature choose which to do? The answer is that nature does all these things in proportion to the amount of raw material available. At the start of the process, there are only high energy photons around, so only the splitting process goes. But once all the fields are of roughly the same intensity, then both processes occur.

People who make optical parametric oscillators talk about back conversion, where the signal and idler start recombining to make more of the input laser beam. This is generally referred to as something to be avoided. What Longhi has discovered is the exact conditions under which perfect back conversion results. And, yet again, because the signal and idler beams need to have exactly the right relationship to each other, this is a coherent process.

Even with all this fancy photon splitting, this is still just impedance matching and classical interference.

If this is just a new take on an old problem, why is it in a journal? Sometimes it is worth taking a new look at old ideas. It is perfectly correct to say that CPA as it is currently discussed is nothing beyond classical impedance matching. But it provides a new way of looking at these ideas. And that is a good thing because, although it never changes the data or the physics, it changes what we think we can do with the physics. Often this sort of publication ends up derided by those who understand it, and hailed as a great breakthrough by those who dont. The truth will lie in what comes of this new view of old phenomena.

Physical Review Letters, 2011, DOI: 10.1103/PhysRevLett.107.033901


7.8 LASER weapon countermeasures



Because lasers are basically light, a number of everyday means can be used to diminish their effectiveness. Their performance can be significantly decreased or negated altogether by phenomena like fog, rain, snow, smoke, and so on, which can disperse or refract the weapons beam to ineffectualness, depending on how thick it is.

Reflective surfaces also present an obstacle, bouncing the beam off a potential target, but this is not as big an impediment as one would tend to think. Mirrors are usually frequency-specific; one that reflects visible light will not necessarily reflect UV or infrared wavelengths, making them vulnerable to weapons that can easily change their beam wavelength. Also, mirror quality is an issue. Most mirrored surfaces are not 100% smooth, meaning that some of the energy from the laser will be absorbed by it, probably melting or marring the reflective surface. Thus unless the mirror unusually tough and is smooth down to its component molecules, it probably wont be able to reflect a laser hit in the same spot more than once or twice.

Also, with visible light lasers, objects that happen to have the exact same color as the beam can completely neutralize the laser, no matter what material its made of. Like mirrors, theres still the problem of energy absorption eventually degrading such a defense, but something as simple as a cotton blanket with the right color can degrade or deflect a tank-destroying multi-megajoule beam. Manufacturers of non-tunable laser weapons would probably go out of their way to make sure the color of their laser beams were not that common in real life.

Reflective surfaces and same-color pigments would be of dubious value against laser weapons with changeable frequencies. Besides, having a highly-reflective or bright surface easily found by enemy sensors would be a profound disadvantage that may significantly outweigh any protection provided.



One unusual but effective defence against lasers would be aerosol dispensers. These come in either a "bomb" form (where a canister of compressed air releases the substance omni-directionally from a casing) or spray-can form. Either way, the aerosol would pump ultrafine but reflective particles into the air around a potential target. The particles would be fine enough to hang suspended in the air from several minutes to up to half an hour, depending on weather and wind conditions. A laser beam hitting these particles would disperse just as if it had hit a thick dust cloud, even though to the naked eye the area would appear only mildly hazy. Again, though, the reflective properties of the aerosol particles may only work against certain wavelengths.



Another defence would be ablative armour, usually made of an array of tightly-clustered gel or foam packs. When a laser hits one of these packs, the heat from the laser instantly boils the gel or foam away, the explosive reaction almost instantly absorbing, dispersing, and redirecting most of the laser energy away from the target. This is much like modern day explosive reactive armour, but carried out on a much smaller scale. Like reflective surfaces, ablative armour would not be effective if hit more than once in the same spot.


If room-temperature superconductors are ever developed, an even more effective defence against lasers becomes available. Fabric interwoven with superconductor wire would instantly absorb the incoming electromagnetic energy of the laser beam and disperse it evenly over its entire surface area. The energy re-radiates almost instantly into the surrounding air as heat. The laser would have to pump enough energy to completely destroy the entire armour all at once before it could penetrate through to its true target. If the superconductor mesh in the armour were cooled via refrigeration unit or a heat sink, even more energy would be required to overcome the armour.


8. Is QCLs tech a safe tech for QCL system users and people around ?


8.1 About LASER

LASER is an acronym that stands for Light Amplification by Stimulated Emission of Radiation. The energy generated by the laser is in or near the optical portion of the electromagnetic spectrum. Energy is amplified to extremely high intensity by an atomic process called stimulated emission. The term radiation is often misinterpreted because the term is also used to describe radioactive materials or ionizing radiation. The use of the word in this context, however, refers to an energy transfer. Energy moves from one location to another by conduction, convection, and radiation. The colour of laser light is normally expressed in terms of the lasers wavelength. The most common unit used in expressing a lasers wavelength is a nanometer (nm). There are one billion nanometers in one meter (1 nm = 1 X 10-9 m). Laser light is nonionizing and includes ultra-violet (100-400nm), visible (400-700nm), and infrared (700nm - 1mm).



Figure 34. A helium-neon laser demonstration at the Kastler-Brossel Laboratory at Univ. Paris 6. The pink-orange glow running through the centre of the tube is from the electric discharge which produces incoherent light, just as in a neon tube. This glowing plasma is excited and then acts as the gain medium through which the internal beam passes, as it is reflected between the two mirrors. Laser radiation output through the front mirror can be seen to produce a tiny (about 1mm in diameter) intense spot on the screen, to the right. Although it is a deep and pure red colour, spots of laser light are so intense that cameras are typically overexposed and distort their colour.


Every electromagnetic wave exhibits a unique frequency, and wavelength associated with that frequency. Just as red light has its own distinct frequency and wavelength, so do all the other colours. Orange, yellow, green, and blue each exhibit unique frequencies and wavelengths. While we can perceive these electromagnetic waves in their corresponding colours, we cannot see the rest of the electromagnetic spectrum. Most of the electromagnetic spectrum is invisible, and exhibits frequencies that traverse its entire breadth. Exhibiting the highest frequencies are gamma rays, x-rays and ultraviolet light. Infrared radiation, microwaves, and radio waves occupy the lower frequencies of the spectrum. Visible light falls within a very narrow range in between.


Figure 35. Components of a typical laser:1. Gain medium2. Laser pumping energy3. High reflector4. Output coupler 5. Laser beam

A laser is a device that emits light (electromagnetic radiation) through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation.[1][2] The emitted laser light is notable for its high degree of spatial and temporal coherence, unattainable using other technologies.

Spatial coherence typically is expressed through the output being a narrow beam which is diffraction-limited, often a so-called "pencil beam." Laser beams can be focused to very tiny spots, achieving a very high irradiance. Or they can be launched into a beam of very low divergence in order to concentrate their power at a large distance.

Temporal (or longitudinal) coherence implies a polarized wave at a single frequency whose phase is correlated over a relatively large distance (the coherence length) along the beam.[3] A beam produced by a thermal or other incoherent light source has an instantaneous amplitude and phase which vary randomly with respect to time and position, and thus a very short coherence length.

Most so-called "single wavelength" lasers actually produce radiation in several modes having slightly different frequencies (wavelengths), often not in a single polarization. And although temporal coherence implies monochromaticity, there are even lasers that emit a broad spectrum of light, or emit different wavelengths of light simultaneously. There are some lasers which are not single spatial mode and consequently their light beams diverge more than required by the diffraction limit. However all such devices are classified as "lasers" based on their method of producing that light: stimulated emission. Lasers are employed in applications where light of the required spatial or temporal coherence could not be produced using simpler technologies.

Stimulated emission

In the classical view, the energy of an electron orbiting an atomic nucleus is larger for orbits further from the nucleus of an atom. However, quantum mechanical effects force electrons to take on discrete positions in orbitals. Thus, electrons are found in specific energy levels of an atom, two of which are shown below:

When an electron absorbs energy either from light (photons) or heat (phonons), it receives that incident quanta of energy. But transitions are only allowed in between discrete energy levels such as the two shown above. This leads to emission lines and absorption lines.


Stimulated Emission.svg


Figure 36. Stimulated emission from a LASER

When an electron is excited from a lower to a higher energy level, it will not stay that way forever. An electron in an excited state may decay to a lower energy state which is not occupied, according to a particular time constant characterizing that transition. When such an electron decays without external influence, emitting a photon, that is called "spontaneous emission". The phase associated with the photon that is emitted is random. A material with many atoms in such an excited state may thus result in radiation which is very spectrally limited (centered around one wavelength of light), but the individual photons would have no common phase relationship and would emanate in random directions. This is the mechanism of fluorescence and thermal emission.

An external electromagnetic field at a frequency associated with a transition can affect the quantum mechanical state of the atom. As the electron in the atom makes a transition between two stationary states (neither of which shows a dipole field), it enters a transition state which does have a dipole field, and which acts like a small electric dipole, and this dipole oscillates at a characteristic frequency. In response to the external electric field at this frequency, the probability of the atom entering this transition state is greatly increased. Thus, the rate of transitions between two stationary states is enhanced beyond that due to spontaneous emission. Such a transition to the higher state is called absorption, and it destroys an incident photon (the photon's energy goes into powering the increased energy of the higher state). A transition from the higher to a lower energy state, however, produces an additional photon; this is the process of stimulated emission.

COMPONENTS OF A LASER (Laser Fundamentals Robert Aldrich)

As shown in figure 3, the three basic components of a laser are:

  • Lasing material (crystal, gas, semiconductor, dye, etc...)
  • Pump source (adds energy to the lasing material , e.g. flash lamp, electrical current to cause electron collisions, radiation from a laser, etc.)
  • Optical cavity consisting of reflectors to act as the feedback mechanism for light amplification

Figure 37. Solid State Laser Diagram

Electrons in the atoms of the lasing material normally reside in a steady-state lower energy level. When light energy from the flashlamp is added to the atoms of the lasing material, the majority of the electrons are excited to a higher energy level -- a phenomenon known as population inversion. This is an unstable condition for these electrons. They will stay in this state for a short time and then decay back to their original energy state. This decay occurs in two ways: spontaneous decay -- the electrons simply fall to their ground state while emitting randomly directed photons; and stimulated decay -- the photons from spontaneous decaying electrons strike other excited electrons which causes them to fall to their ground state. This stimulated transition will release energy in the form of photons of light that travel in phase at the same wavelength and in the same direction as the incident photon. If the direction is parallel to the optical axis, the emitted photons travel back and forth in the optical cavity through the lasing material between the totally reflecting mirror and the partially reflecting mirror. The light energy is amplified in this manner until sufficient energy is built up for a burst of laser light to be transmitted through the partially reflecting mirror.

As shown in figure 4, a lasing medium must have at least one excited (metastable) state where electrons can be trapped long enough (microseconds to milliseconds) for a population inversion to occur. Although laser action is possible with only two energy levels, most lasers have four or more levels.

Figure 38. Three level laser energy diagram

A Q-switch in the optical path is a method of providing laser pulses of an extremely short time duration. A rotating prism like the total reflector in figure 3 was an early method of providing Q-switching. Only at the point of rotation when there is a clear optical path will light energy be allowed to pass. A normally opaque electro-optical device (e.g., a pockels cell) is now often used for a Q-switching device. At the time of voltage application, the device becomes transparent, the light built up in the cavity by excited atoms can then reach the mirror so that the cavity Quality, Q, increases to a high level and emits a high peak power laser pulse of a few nanoseconds duration. When the phases of different frequency modes of a laser are synchronized (locked together), these modes will interfere with each other and generate a beat effect. The result is a laser output with regularly spaced pulsations called "mode locking". Mode locked lasers usually produce trains of pulses with a duration of a few picoseconds to nanoseconds resulting in higher peak powers than the same laser operating in the Q-switched mode. Pulsed lasers are often designed to produce repetitive pulses. The pulse repetition frequency, prf, as well as pulse width is extremely important in evaluating biological effects.

The laser diode is a light emitting diode with an optical cavity to amplify the light emitted from the energy band gap that exists in semiconductors as shown in figure 39. They can be tuned by varying the applied current, temperature or magnetic field.

Figure 39. Semiconductor laser diagram

Gas lasers consist of a gas filled tube placed in the laser cavity as shown in figure 40. A voltage (the external pump source) is applied to the tube to excite the atoms in the gas to a population inversion. The light emitted from this type of laser is normally continuous wave (CW). One should note that if brewster angle windows are attached to the gas discharge tube, some laser radiation may be reflected out the side of the laser cavity. Large gas lasers known as gas dynamic lasers use a combustion chamber and supersonic nozzle for population inversion.

Figure 40. Gas laser diagram

Figure 41 shows a dye laser diagram. Dye lasers employ an active material in a liquid suspension. The dye cell contains the lasing medium. Many dyes or liquid suspensions are toxic.

Figure 41. Common Dye Laser Diagram

Free electron lasers such as in figure 42 have the ability to generate wavelengths from the microwave to the X-ray region. They operate by having an electron beam in an optical cavity pass through a wiggler magnetic field. The change in direction exerted by the magnetic field on the electrons causes them to emit photons.


Figure 42. Free Electron Laser Diagram

Laser beam geometries display transverse electromagnetic (TEM) wave patterns across the beam similar to microwaves in a wave guide. Figure 43 shows some common TEM modes in a cross section of a laser beam.


Figure 43 Common TEM laser beam modes

A laser operating in this mode could be considered as two lasers operating side by side. The ideal mode for most laser applications is this mode and this mode is normally assumed to easily perform laser hazards analysis. Light from a conventional light source is extremely broadband (containing wavelengths across the electromagnetic spectrum). If one were to place a filter that would allow only a very narrow band of wavelengths in front of a white or broadband light source, only a single light color would be seen exiting the filter. Light from the laser is similar to the light seen from the filter. However, instead of a narrow band of wavelengths none of which is dominant as in the case of the filter, there is a much narrower linewidth about a dominant center frequency emitted from the laser. The color or wavelength of light being emitted depends on the type of lasing material being used. For example, if a Neodymium:Yttrium Aluminum Garnet (Nd:YAG) crystal is used as the lasing material, light with a wavelength of 1064 nm will be emitted. Table 1 illustrates various types of material currently used for lasing and the wavelengths that are emitted by that type of laser. Note that certain materials and gases are capable of emitting more than one wavelength. The wavelength of the light emitted in this case is dependent on the optical configuration of the laser.

Table 2. Common Lasers and Their Wavelengths


WAVELENGTH (Nanometers)

Argon Fluoride


Xenon Chloride

308 and 459

Xenon Fluoride

353 and 459

Helium Cadmium

325 - 442

Rhodamine 6G

450 - 650

Copper Vapor

511 and 578


457 - 528 (514.5 and 488 most used)

Frequency doubled Nd:YAG


Helium Neon

543, 594, 612, and 632.8


337.5 - 799.3 (647.1 - 676.4 most used)



Laser Diodes

630 - 950


690 - 960


720 - 780



Hydgrogen Fluoride

2600 - 3000



Carbon Monoxide

5000 - 6000

Carbon Dioxide



 8.2 Hazards from LASER use

Lasers have become increasingly important research tools in Medicine, Physics, Chemistry, Geology, Biology and Engineering. If improperly used or controlled, lasers can produce injuries (including burns, blindness, or electrocution) to operators and other personnel, including uninitiated visitors to laboratories, and cause significant damage to property. Individual users of all lasers must be adequately trained to ensure full understanding of the safety practices (The University of Texas in Austin Laser Safety Policy ) .


The Laser Safety procedures follow the requirements of the Department of Texas Health Bureau of Radiation Control, and the guidelines from the American National Standards Institute (ANSI) as specified in the ANSI Standards Z136.1, The Safe Use of Lasers.



Figure 44. Warning symbol and labels for lasers


The laser produces an intense, highly directional beam of light. If directed, reflected, or focused upon an object, laser light will be partially absorbed, raising the temperature of the surface and/or the interior of the object, potentially causing an alteration or deformation of the material.

These properties which have been applied to laser surgery and materials processing can also cause tissue damage.

In addition to these obvious thermal effects upon tissue, there can also be photochemical effects when the wavelength of the laser radiation is sufficiently short, i.e., in the ultraviolet or blue region of the spectrum. Today, most high-power lasers are designed to minimize access to laser radiation during normal operation. Lower-power lasers may emit levels of laser light that are not a hazard.


The human body is vulnerable to the output of certain lasers, and under certain circumstances, exposure can result in damage to the eye and skin. Research relating to injury thresholds of the eye and skin has been performed in order to understand the biological hazards of laser radiation.


It is now widely accepted that the human eye is more vulnerable to injury than human skin. The cornea (the clear, outer front surface of the eyes optics), unlike the skin, does not have an external layer of dead cells to protect it from the environment. In the far-ultraviolet regions of the optical spectrum, the cornea absorbs the laser energy and may be damaged. At certain wavelength in the near-ultraviolet region and in the near-infrared region, the lens of the eye may be vulnerable to injury.


Of greatest concern, however, is laser exposure in the retinal hazard region of the optical spectrum, approximately 400 nm (violet light) to 1400 nm (near-infrared) and including the entire visible portion of the optical spectrum. Within this spectral region collimated laser rays are brought to focus on a very tiny spot on the retina. In order for the worst case exposure to occur, an individuals eye must be focused at a distance and a direct beam or specular (mirror-like) reflection must enter the eye. The light entering the eye from a collimated beam in the retinal hazard region is concentrated by a factor of 100,000 times when it strikes the retina.


Therefore, a visible, 10 milliwatt/cm2 laser beam would result in a 1000 watt/cm2 exposure to the retina, which is more than enough power density (irradiance) to cause damage. If the eye is not focused at a distance or if the beam is reflected from a diffuse surface (not mirror-like), much higher levels of laser radiation would be necessary to cause injury. Since this ocular focusing effect does not apply to the skin, the skin is far less vulnerable to injury from these wavelengths.

From : The University of Texas in Austin Laser Safety Policy.


Lasers can easily, permanently blind a person with unprotected eyesight. Some lasers, called dazzlers, are specifically designed for this. However, any laser of significant power can also cause occular damage by reflection or diffraction off a target surface to any soldier who was unlucky enough to be caught too close.

The most obvious defence against this are high-quality, impact-resistant, full-vision (fully covering the eyes and leaving no gaps for unwanted light to get through) sunglasses whose protection extends both into the infrared and ultraviolet bandwidths.


9. Could terrorists cause problems to QCL tech systems for explosives detection ?


The use of LASER beam technology is vulnerable to anti-systems ( from terrorists or hostile forces) which could be a lethal trap for detection systems using LASER beams, creating civilian casualties, bringing panic to similar operators and many other consequences.




Figure 45 Simply Anti - QCL tech lethal trap for detection systems using LASER beams


By placing on the explosive matter an identification system (12) of the impacting laser beam (a temperature difference counting sensor) and connecting it to an electrical detonator with a suitable, independent electronic control circuit, could the terrorist or enemy forces cause a distraction blast of the explosive matter or IDE, in case that the LASER beam (red line) hits the temperature difference counting sensor. (bellow figure)





Figure 46 A QCL detection systems blasting an IDE using LASER beam



In such a case the results could be catastrophic, as the minimum safe distance from a TNT half pound (250 grams) explosive matter is 300 meters minimum in a clear field, where there are no objects scattered around (stones, cars, wood etc.).

In fact such actions if terrorists do it - will cause psychological panic to laser detection systems users and vehicle crew. It is more than sure that after the first incident users of those systems would avoid targeting points, assuming that there are such a trapped explosives (particularly IDE).


To certify those claims of mine, I refer the reader of this reference to the patent no GR20050100163  (A) 2006-11-01 (this is a patent of mine) GROUND PORTABLE SYSTEM FOR THE LOCATION AND DESTRUCTION OF LOW-FLYING HELICOPTERS, AIRCRAFTS, HOVERCRAFTS OR THE LIKE .


For low flying helicopters and low flying aircrafts :





- international:

F42B23/04; F42C13/00; F42C15/40; F41H11/02

- European:


Application number: GR20050100163 20050331  Priority number(s): GR20050100163 20050331 


Here is an Abstract

It is disclosed herein an energetically autonomous portable system designed for the detection and destruction of predefined moving targets flying at a very low height from the ground, which system utilizes micro-electronic technology means for the localisation of predefined targets such as helicopters, aircrafts of VISTOL type, hovercrafts, hang gliders, parachutists or whatever flying means whose electronic signature has been previously defined and parameterized with the use of three electric sensors 11 based on three different operation principles (one magnetic sensor 16, one sensor 20 sensing the pressure in the atmosphere and one sensor sensing the heat of the approached target 54). Said sensors locate and identify the predefined standards of targets; when the target approaches to a distance of 50 to 10 metres from the system, they automatically send electric current of adequate intensity and voltage to an electric detonator 4 actuating the explosive filling 3 of the system composed of 40 one-one pound-plates of trinitrotoluol (TNT) 14 placed in a precise manner into a plastic casing 1 which is 50 cm x 50 cm x 50 cm in size and completely full with a great number of metal balls 8 of 0,25 to 1 cm diameter. The invention constitutes a valid and scientifically documented solution based on the up-to-date microelectronic technology. It establishes a universal precedent since its defensive system is able to impede the landing of any kind of flying means, the passage of hovercrafts of any dimensions and any kind of air and sea disembarkation by helicopters, parachutes, or hovercrafts. Its use is ideal for the hindering of enemy air landing operations attempted by any known flying means. Damage is always depending on the ground texture: Flying means will be seriously damaged and the crew gravely injured when detected at 100 m range covered by said system; within a 50 m ray the flying means will be completely destroyed and the passengers thereof dead; varying damage will

Other LASER beam anti - systems against cars, vehicles, personnel etc are developed and patent here :

For ships : GR1005392  (B1) 2006-12-18







- international:

B63G7/02; B63G8/00; B63G8/28; B63G8/38

- European:


Application number:

GR20060100001 20060102 

Priority number(s):

GR20060100001 20060102

Abstract of  GR1005392  (B1)

The invention relates to a target-oriented unmanned carriers 1 transporting variable quantities of explosive materials or a precise system creating high-voltage electromagnetic pulses, or two torpedos, or other armour systems (inside or outside their carrier) called automates characterised by automatic or remote navigation, surfacing and submersion into water, which systems detect and recognize -via the advanced microelectronic technology they use- predefined targets whereto said automates are self-moving or remotely navigating by automatically igniting their load, when predefined suitable conditions occur; analogous transporting and supporting systems carry said automates, when these last are used in the sea. Different variants (multi-form, multi-dimensioned, multi-structured carriers) are used in the land or dropped from air by parachutes to cover needs in modern, smart electronically-operating minefields or groups of minefields bearing passive electronic location systems, systems for the recognition of friendly areas, the remote actuation or deactivation, the autonomous target-oriented motion and the potential multiple communication with stationary or mobile administrative and monitoring stations in air, land, sea and space; all the above operate as a single tactical or strategic operational system capable for target-oriented motion, immersion and surfacing, automatic or remote actuation and deactivation, tactical or strategic supervision, image transmission in real time and recognition of friendly areas and means. These automates exhibit the same destructive effects in case of transport of a system creating high-voltage electromagnetic pulses in land, sea and air; their use allows, in short time, the mining of friendly coasts against enemy debarkations, the blockade of enemy harbours for long periods of time, the flight prohibition for aircrafts and helicopters and all up-to-date modern prohibiting operations aiming at the destruction of electronic and electric


On land : 1. GR20050100298  (A) 2007-01-19



Page bookmark







- international:

F42B23/00; F42B23/24; F42C11/00; F42C13/02; F42C13/06; F42C13/08; G06K9/32

- European:


Application number:

GR20050100298 20050615 

Priority number(s):

GR20050100298 20050615

Abstract of  GR20050100298  (A)

The invention relates to a portable, energetically autonomous defence system designed for the location and destruction of predefined targets. Said defence system is provided with eight electronic sensors (55,56,57,58,59,60,61,62) serving three different operational purposes (heat detection, detection of the disturbance of the earth magnetic field, detection of the sound waves) and allows the automatic location of predefined and electronically parameterised targets laid on the ground or flying at low height up to 50 metres; the targets are detected via an adequate real-time electronic system 7 by application of the electronic signature technique (pattern recognition) based on the activation from a predefined distance of a suited explosive trinitrotolouol (TNT) filling. The explosive filling, the sensors, the loading system 16 and the electronic system 7 are incorporated into a metal spherical framework 48 coated with special plastic casing 33 presented in three dimensions (30,40 and 60cm) in respect to the kind of the target to be located. The invention concerns up-to-date electronic mines of full exploitation range lunched by the defendant's hand 89 and rolling by gravity action towards the desired mined region in order to neutralize, in the 5 min of ceasefire, mines spread out during multi-hour bombarding.


On land & air : 2 : GR20050100185  (A) 2006-11-23



Page bookmark







- international:

F42B22/04; F42B23/04; F42C13/00; F42C15/40

- European:


Application number:

GR20050100185 20050411 

Priority number(s):

GR20050100185 20050411

Abstract of  GR20050100185  (A)

An amphibian quickly deployed and energetically autonomous system is disclosed for the location and destruction of targets moving on water or on land or up to 50 metres over the ground, in the form of a rectangular parallelepiped of 140 x 10 x 10-50metres in dimensions. Upon appearance of the target, the system in question is in position to locate this last (boats, passengers crafts, amphibious lightly armoured vehicles, helicopters, aircrafts, hovercrafts, parachutists etc) with the assistance of eight electronic sensors accomplishing three different functions: they detect the change of the earth's magnetic field 16, the pressure of the atmosphere 20, and the heat 54. After the target is identified, an electric charge of 5 volt is sent from a microprocessor 34 to a common electric detonator 4 actuating the explosive filling 3 of 40 Libras of TNT explosives 14 and creating a strong explosive wave launching metal balls 8 at a range of 300 m in the space around. The system is hand or remotely loaded 58 and provided with a quick mine-laying or -spreading system efficiently answering the need for quick laying of mines on coasts and prohibiting thus any land or air debarkations in supervised areas (rocky islands, small islands, parachutists zones, helicopters landing zones, regions under protection etc)


On land : 3 : GR20050100074  (A) 2006-10-06



Page bookmark







- international:

F42B23/00; F42B23/04

- European:


Application number:

GR20050100074 20050217 

Priority number(s):

GR20050100074 20050217

Abstract of  GR20050100074  (A)

The invention relates to a system, the use of which allows the conversion of a variety of conventional old-technology anti-tank landmines (20), acting by the energy of the shock wave from the gas expansion on the target, from various manufacturers and countries, into a modern-technology, hollow-charge landmine with full exploitation range, consisting of a metallic carrier (83) which is arranged around the explosive charge (21) -after removing, by mechanical means, all the mechanical parts (27) of the landmine, its old casing, and transforming the shape of landmine explosive charge (21), so that its upper part has a conical shape with the cone tip lying to the ground, in order to be converted into a hollow charge (31) for creating a narrow focused (73), but highly penetrating fire beam (72)- and a special plastic or metallic shell (74) having a conical protrusion on its lower part (79), which is screwed stably on thread (82) existing on the landmine shell, when the landmine is to be used, the shell enclosing a special microelectronic device (13) for locating and identifying the target and for triggering the landmine by the use of an electrical detonator mechanism that is triggered by an electric signal from the microelectronic system when the target is identified electronically and reaches a predetermined distance from the landmine. By this invention the old-technology conventional landmines are fully exploited and the problems of undesirable casualties due to undesirable triggering of the old-technology landmines (animal or illegal immigrants passing etc.) and of substantial environmental burden due to the demanded destruction thereof are highly solved


On land : 4 : GR1004706  (B1) 2004-10-25 (SPECIALLY THIS PATENT )



Page bookmark







- international:

F42B23/00; F42C13/00; F42C19/02; (IPC1-7): F42B23/00; F42C13/00; F42C19/02

- European:


Application number:

GR20040100120 20040406 

Priority number(s):

GR20040100120 20040406

Abstract of  GR1004706  (B1)

A portable self-automated system destined for the localization and destruction of predefined moving targets with electronic means is disclosed. The multiform design of said system allows the user -with respect to the kind of the target and the destruction degree he desires- to opt among four differentcasings wherein a predefined quantity of standardized plates of TNT explosion material is placed in due time. Then, an electronic sub-system screws on the selected by the user casing to localize and actuate the explosive filling with which a wide range of moving ground targets -from a mere bicycle to the heaviest tank- may be localized and identified, thanks to an incorporated-to-the-system real-time microelectronic system functioning on the principle of the target's electronic signature detection. Vehicles, bikes, tanks, and other objects-targets are detected, localized and accurately defined by three electronic sensors based on different operation principles. When the electronic signature of the predefined target is localized at a predefined distance from the explosive filling, the real-time system supplies sufficient output voltage leading to the electric detonator's explosion; the produced thereby explosion wave is capable of actuating the adjacent to the detonator TNT-type explosive material and all TNT fillings contained in the casing so that the explosive filling of the system is globally and efficiently exploded. The user opting, according to circumstances, for a convenient position of the system, predefines the desired damage degree ranging from partial neutralization to total destruction of the target. In the sequel, the TNT plates are introduced in the selected casing and the localisation and actuation sub-systemis added to the system which is liable to operate either buried under soil (about 3-5 cm deep) or positioned on the ground with equivalent efficiency results. Target destruction may also be achieved by connection of one or two ordinary M15 and M6 min..


On land : 5 : GR1004848  (B1) 2005-04-04



Page bookmark







- international:

F41H11/00; G08B13/16; (IPC1-7): F41H11/00; G08B13/16

- European:


Application number:

GR20040100086 20040309 

Priority number(s):

GR20040100086 20040309

Abstract of  GR1004848  (B1)

The invention relates to a portable, low cost and energetically autonomous device functioning on the ground or under the ground. It is suitable for being thrown by aircrafts or helicopters and able to localize, with the assistance of the microelectronic technology, targets such as humans, animals, vehicles, lorries, machines, tanks or objects moving on the ground surface, and transmit, constantly and in real time, information about these targets, in wired or wireless manner, to a remote computing system or to a satellite. Applying the principle of the target's electronic signature detection, it automatically localizes the target with use of three differently operating sensors. It exploits the cellular private or military communication networks and interchanges data with these last in real time; additionally, information about approached targets can be delivered, in wired or wireless manner, to independent weapon systems able to automatically or remotely fire rockets, mines, rifle grenades, improvised or singular traps, artillery missiles, rockets, antitank weapons and other support firing.


For more information : http://www.geoment.e-e-e.gr/def_cat_prod.htm


10 . Directed-energy weapons problems


Figure 47. In combat use LASER

A directed-energy weapon (DEW) emits energy in an aimed direction without the means of a projectile. It transfers energy to a target for a desired effect. Intended effects may be non-lethal or lethal. Some such weapons are real, or are under active research and development.

The energy can come in various forms:

Some such weapons, perhaps most, at present only appear in science fiction, non-functional toys, film props or animation.

In science fiction, these weapons are sometimes known as death rays or rayguns and are usually portrayed as projecting energy at a person or object to kill or destroy. Many modern examples of science fiction have more specific names for directed energy weapons, due to research advances.

Laser weapons could have several main advantages over conventional weaponry:

  • Laser beams travel at the speed of light, so there is no need (except over very long distances) for users to compensate for target movement when firing over long distances. Consequently, evading a laser after it has been fired is impossible.
  • Because of the extremely high speed of light it is only slightly affected by gravity, so that long range projection requires little compensation. Other aspects such as wind speed can be neglected at most times, unless shooting through an absorption matter.
  • Lasers can change focusing configuration to provide an active area that can be much smaller or larger than projectile weaponry.
  • Given a sufficient power source, laser weapons could essentially have limitless ammunition.
  • Because light has a practically nil ratio (exactly 1/c) of momentum to energy, lasers produce negligible recoil.
  • The operational range of a laser weapon can be much larger than that of a ballistic weapon, depending on atmospheric conditions and power level.

Modern ballistic weapons commonly feature systems to counter many undesirable side-effects mentioned for them in the above comparison. As such it follows that laser weapons' advantage over ballistics could end up more about elegance and cost.

10.1 Problems and considerations

10.1.1 Blooming

Laser beams begin to cause plasma breakdown in the air at energy densities of around a megajoule per cubic centimeter. This effect, called "blooming," causes the laser to defocus and disperse energy into the atmosphere. Blooming can be more severe if there is fog, smoke, or dust in the air.

Reducing blooming:

  • Spread the beam across a large, curved mirror that focuses the power on the target, to keep energy density en route too low for blooming to happen. This requires a large, very precise, fragile mirror, mounted somewhat like a searchlight, requiring bulky machinery to slew the mirror to aim the laser.
  • Use a phased array. For typical laser wavelengths this method requires billions of micrometre-size antennae. No way to make these is known. However, carbon nanotubes have been proposed. Phased arrays could theoretically also perform phase-conjugate amplification (see below). Phased arrays do not require mirrors or lenses, can be made flat and thus do not require a turret-like system (as in "spread beam") to be aimed, though range will suffer at extreme angles (that is, the angle the beam forms to the surface of the phased array).[1]
  • Use a phase-conjugate laser system. Here, a "finder" or "guide" laser illuminates the target. Any mirror-like ("specular") points on the target reflect light that is sensed by the weapon's primary amplifier. The weapon then amplifies inverted waves in a positive feedback loop, destroying the target with shockwaves as the specular regions evaporate. This avoids blooming because the waves from the target passed through the blooming, and therefore show the most conductive optical path; this automatically corrects for the distortions caused by blooming. Experimental systems using this method usually use special chemicals to form a "phase-conjugate mirror". In most systems, the mirror overheats dramatically at weapon-useful power levels.
  • Use a very short pulse that finishes before blooming interferes.
  • Focus multiple lasers of relatively low power on a single target.

10.1.2. Evaporated target material

Another problem with weaponized lasers is that the evaporated material from the target's surface begins to shade. There are several approaches to this problem:

  • Induce a standing shockwave in the ablation cloud. The shockwave then continues to perform damage.
  • Scan the target faster than the shockwave propagates
  • Induce plasmic optical mixing at the target. Modulate the transparency of the target's ablation cloud to one laser by another laser, perhaps by tuning the laser to the absorption spectra of the ablation cloud, and inducing population inversion in the cloud. The other laser then induces local lasing in the ablation cloud. The beat frequency that results can induce frequencies that penetrate the ablation cloud.

10.1.3. High power consumption

One major problem with laser weapons (and directed-energy weapons in general) is their high electric energy requirements. Existing methods of storing, conducting, transforming, and directing energy are inadequate to produce a convenient hand-held weapon. Existing lasers waste much energy as heat, requiring still-bulky cooling equipment to avoid overheating damage. Air cooling could yield an unacceptable delay between shots. These problems, which severely limit laser weapon practicality at present, might be offset by:

  1. Cheap high-temperature superconductors to make the weapon more efficient.
  2. More convenient high volume electricity storage/generation. Part of the energy could be used to cool the device.

Chemical lasers use energy from a suitable chemical reaction instead. Chemical oxygen iodine laser (hydrogen peroxide with iodine) and deuterium fluoride laser (atomic fluorine reacting with deuterium) are two laser types capable of megawatt-range continuous beam output. Managing chemical fuel presents other problems, so the problems of cooling and overall inefficiency remain.

This problem could also be lessened if the weapon were mounted either at a defensive position near a power plant, or on board a large, possibly nuclear powered, water-going ship. A ship would have the advantage of water for cooling.

10.1.4. Beam absorption

A laser beam or particle beam passing through air can be absorbed or scattered by rain, snow, dust, fog, smoke, or similar visual obstructions that a bullet would easily penetrate. This effect adds to blooming problems and makes the dissipation of energy into the atmosphere worse.

The wasted energy can disrupt cloud development since the impact wave creates a "tunneling effect". Engineers from MIT and the U.S. Army are looking into using this effect for precipitation management.

10.1.5. Lack of indirect fire capabilities

Indirect fire, as used in artillery warfare, can reach a target behind a hill, but is not feasible with line-of-sight DEWs. Possible alternatives are to mount the lasers (or perhaps just reflectors) on airborne or space-based platforms.

10.2 Lasers

Lasers are often used for sighting, ranging and targeting for guns; but the laser beam is not the source of the weapon's firepower.

Laser weapons usually generate brief high-energy pulses. A one megajoule laser pulse delivers roughly the same energy as 200 grams of high explosive, and has the same basic effect on a target. The primary damage mechanism is mechanical shear, caused by reaction when the surface of the target is explosively evaporated.

Most existing weaponized lasers are gas dynamic lasers. Fuel, or a powerful turbine, pushes the lasing media through a circuit or series of orifices. The high-pressures and heating cause the medium to form a plasma and lase. A major difficulty with these systems is preserving the high-precision mirrors and windows of the laser resonating cavity. Most systems use a low-powered "oscillator" laser to generate a coherent wave, and then amplify it. Some experimental laser amplifiers do not use windows or mirrors, but have open orifices, which cannot be destroyed by high energies.[citation needed]

Some lasers are used as non-lethal weapons, such as dazzlers which are designed to temporarily blind or distract people or sensors.

10.3 Electrolaser

Main article: Electrolaser

An electrolaser lets blooming occur, and then sends a powerful electric current down the conducting ionized track of plasma so formed, somewhat like lightning. It functions as a giant high energy long-distance version of the Taser or stun gun.

10.4 Radio frequency

High-energy radio-frequency weapons (HERF) work on the same principles as microwave ovens, have also shown potential.

On January 25, 2007 the US Army unveiled a device mountable on a small armored vehicle (Humvee). It resembles a planar array. It can make people feel as if the skin temperature is around 130 F (54 C) from around 500 yards (460 m) away. Full scale production of such a weapon was not expected until at least 2010[citation needed]. It is probably most usefully deployed as an Active Denial System.

10.5 Microwaves

Microwave guns powerful enough to injure humans are possible:

  • Active Denial System is a millimeter wave source that heats the water in the target's skin and thus causes incapacitating pain. It is being used by the U.S. Air Force Research Laboratory and Raytheon for riot-control duty. Though intended to cause severe pain while leaving no lasting damage, some concern has been voiced as to whether the system could cause irreversible damage to the eyes. There has yet to be testing for long-term side effects of exposure to the microwave beam. It can also destroy unshielded electronics: see TEMPEST (research into unintended electronic release of information).[2] The device comes in various sizes including attached to a humvee.
  • Vigilant Eagle is an airport defense system that directs high-frequency microwaves towards any projectile that is fired at an aircraft.[3] The system consists of a missiledetecting and tracking subsystem (MDT), a command and control system, and a scanning array. The MDT is a fixed grid of passive infrared (IR) cameras. The command and control system determines the missile launch point. The scanning array projects microwaves that disrupt the surface-to-air missile's guidance system, deflecting it from the aircraft.[4]
  • Bofors HPM Blackout is a high-powered microwave weapon system which is stated to be able to destroy at distance a wide variety of commercial off-the-shelf (COTS) electronic equipment. It is stated to be not lethal to humans.

10.6 Pulsed Energy Projectile

Pulsed Energy Projectile or PEP systems emit an infrared laser pulse which creates rapidly expanding plasma at the target. The resulting sound, shock and electromagnetic waves stun the target and cause pain and temporary paralysis. The weapon is under development and is intended as a non-lethal weapon in crowd control.

10.6.1 Effects and Uses

When used against humans electromagnetic weapons can have dramatic effects, such as the intense burning sensation caused by Raytheon's Active Denial system, or more subtle effects such as the creationat a distanceof a sense of anxiety or dread, intense drowsiness, or confusion in an individual or a group of people. Three military advantages of such weapons are:

  1. That the individual or group of people would not necessarily realize that they were being targeted by such a device.
  2. That microwave radiation, like some other radio frequency radiation, can easily penetrate most common building materials.
  3. That with specialized antennas the radiation and its effects can be focused on either an individual or a large area such as a city or country.

Potential military(/law enforcement) uses for such weapons include:

  1. Capability to influence an enemy force (or population) to flee rather than to stand and fight by imposing on them a sense of great anxiety or impending disaster
  2. Ability to convince captured enemy combatants that the great sense of physical well-being which seemed to accompany their being even slightly cooperative was much more desirable than the overwhelming sense of uneasiness and dread associated with their being uncooperative or hostile.
  3. Ability to impose a feeling of overwhelming drowsiness on an already weary enemy force.
  4. Ability to deprive an enemy force of sound, uninterrupted sleep for a prolonged period.
  5. Capability to persuade, indirectly, the close comrades of an enemy soldier that the soldier perhaps an infantry officer who admittedly hears voices or strange noises that no one else is hearing is mentally unsound and is not to be taken seriously. Such feelings, voices, or strange noises and dreams can be imposed on the enemy with some precision by specialized, microwave-type radiation antennas.











11.            Conclusions


1. The long distance term in this report is not a range of 91 meters. It refers to several kilometers range.


2. The use of QCLs is not a safe tech. LASER beam could VAPORIZE EVERYTHING that hits on. Absorption - heat removal - plasma exported. Those are the rules. The details of the vapor results. And this is a highly environmental problem for all of us.


3. Although QCLs seems to be an easy tech in action, there are factors, as environmental conditions, properties of the chemical substance, and physics that cannot be controlled by technology.

4. LDCDD using QCLs seems to have a lot of system & personnel survival problems. A low (91 meters ?) flying helicopter is the best target not only for a for a sniper but for anyone that could carry a gun. Already have been developed and patent Anti helicopter mines & traps, that in action could easily destroy those flying LDCDDs .


5. Due to the curvature of the earth's surface, objectives (explosives) targeting can not be done over long distances from LDCDD using QCLs. LASER beam only works straight to the target. Even if QCLs targets up to the target (30 -50 cm) this distance of 0,5 meters in a 1.000 meters range is a 1/2000 ratio.


6. LDCDD using QCLs could not investigate explosives behind any parapet (walls, metal curtain, mountains, hills, etc.) .


7. LDCDD using QCLs under conditions could decepted as laser beam reflected from mirrors that could by placed on or by the IDE or land mine or explosive.


8. LDCDD using QCLs under conditions could miss the target (explosives) as laser beam absorbed from many materials that could by placed on or by the IDE or land mine or explosive. The first and simplest measure that a terrorist will do is to cover explosives with common compact optical discs (CDs DVDs ).


9. LDCDD using QCLs under conditions could delused. Laser beam maybe could not hit the explosives because of a resistant to radiation and beam impact material placed in front of them.


10. LDCDD using QCLs under conditions could foozled. Those systems used the Raman spectrometer tech, based on Spreadable molecules existing in some distance on air from the actual explosive matter. Those molecules does not exist in a vacuum air. If explosives placed in a simple air vacuum system, as simple and chip Vacuum food saver boxes are, could not be detected by LDCDD systems using QCLs.


11. LDCDD using QCLs could soon be rustle. Anti LASER systems developing now days, as LASER SHIELDs for LASER beams are.


12. LDCDD using QCLs could now days inactivated from countermeasures . laser weapon countermeasures are in full technological development. anti-laser aerosols, . ablative armours and superconductive energy dispersive armours are already in use.


13. As LDCDD using QCLs are vulnerable to LASER anti-systems, could become a lethal traps for its users. Anti LASER mines and traps already developed now days. I estimate that terrorists and enemy troops could cause serious problems to LDCDD using QCLs.


14. QCLs tech is not a safe tech in the field for the system users and people around the operation. Hazards from LASER use steel existed now days.

15. Directed-energy weapons, as LASERs are, have already appeared problems. Blooming, Evaporated target material, High power consumption, Beam absorption, Lack of indirect fire capabilities, are only some of those problems.










12. References


STROMATIAS KONSTANTINOS EVA, publication: GR20050100298, uropean Patent Office, GROUND PORTABLE SYSTEM FOR THE LOCATION AND DESTRUCTION OF LOW-FLYING HELICOPTERS, AIRCRAFTS, HOVERCRAFTS OR THE LIKE, publication: GR20050100163  2006-11-01, IPC: F42B23/04; F42C13/00; F42C15/40 (+5), http://www.ep.espacenet.com


Stromatias Kostantinos, Electronic Bombs: ELECTRONIC BOMBS, Cyprus Military review and history, no 17 , Mar 2008.


STROMATIAS KONSTANTINOS EVA, publication: GR1005392, uropean Patent Office, Autonomous underwater floating target-oriented unmanned carriers used for the transportation of explosive materials or other weapons, http://www.ep.espacenet.com

Stromatias Kostantinos, Greek weapons and inventions, STRANGE magazine, no 88, ai 2006.

Stromatias Kostantinos, Directed Energy Weapons in Greece, Secret technology and lost scientist, no 2, Mai 2007. http://www.geoment.e-e-e.gr/empgr.htm Strong Electromagnetic Pulse system

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Explosives Detection Using Magnetic and Nuclear Resonance Techniques by Jacques Fraissard and Université Pierre et Marie Curie Ecole de Physique et Chimie Industrielles, Paris, France & Olga Lapina Boreskov Institute on Catalysis Russian Academy of Sciences, Novosibirsk, Russia. Springer Science + Business Media B.V. 2009 , 79 July 2008

Proceedings of the NATO Advanced Research Workshop on

P.O. Box 17, 3300 AA Dordrecht, The Netherlands.

ISBN 978-90-481-3061-0 (PB) - ISBN 978-90-481-3062 -7 (e-book) - ISBN 978-90-481-3060-3 (HB)

Explosives Detection Using Magnetic and Nuclear Resonance Techniques

Library of Congress Control Number: 2009929398 St. Petersburg, Russia






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