LASER DAMAGE WEAPONS

INTRODUCTION
1. Although the vast number of low powered Laser illuminators, Rangefinders, LADAR and other devices are not specifically designed to be weapons, if observed by the unprotected human eye, they can produce temporary or even permanent blindness. Although banned by international protocol, purpose built Laser Dazzle weapons have been developed and deployed in the field. Additionally, higher-powered Lasers of varying power and complexity have been developed to cause actual physical damage. It is very important to be aware of the threat posed by such weapons and their future potential.

OBJECTIVE
1. The objective for this section is to explain the operation of high and low-power military Laser systems. The following subjects will be covered:
a. Classes of Laser.
b. Dazzle Weapons.
c. High Energy Systems
(1) Land Based Systems.
(2) Airborne systems.
d. Adaptive Optics.
CLASSES OF LASER
2. Lasers can be grouped into certain classes based upon their power and potential for physical damage to the human eye or skin. A term commonly referred to is ‘Aversion’ which is man’s instinctive reaction to “blink “ when illuminated by a high power light or Laser. The Classes are shown in the table below:
Class Power Rating Hazard
1 µ watts Not Hazardous within Aversion response time
2 m watts Hazardous if viewer overcomes Adversion
3 M watts - Watts Causes injury faster than Adversion response
4 Watts Cause skin damage
4. For all Laser systems, including those not designed as Dazzle weapons, there exists what is known as the Normalised Ocular Hazard Distance (NOHD). This is defined as the range where the signal strength from a Laser has reduced to a level considered to be eye safe.
5. The NOHD depends upon the Class of Laser, its wavelength and pulse rate. Typically for a Nd YAG Laser the NOHD is 1 km. During peace time operations there are strict controls on the use of military Laser systems.
DAZZLE WEAPONS
6. It has been a natural and fairly easy step for existing Lasers systems to be developed into Dazzle weapons. A Laser Rifle developed in the US came from a medical Laser. Information about such weapons is very highly classified and difficult to obtain. Damage to the eye can be either temporary or permanent depending upon the class of Laser and type of exposure the eye has received. Brief descriptions of several Dazzle systems follow:
7. The US Army Laser Rifle was developed during the 1980’s. In 1993 it is believed that 1100 Rifles were tested and can cause either temporary or permanent damage. The Beamwidth is assessed as being 0.5 metres at 1 km. However little is known about ranges or the NOHD. The figure below shows a diagram of the Rifle.

8. A Laser weapon known as Stingray was fitted to 2 Bradley Armoured Personnel Carriers and deployed to Saudi Arabia during the Gulf War. The system designator is AN/VLQ-7. Designed to scan the battlefield with an eye safe Laser, the Stingray detects reflections from optical devices such as periscopes and Binoculars. It then illuminates these with a narrow-beam high-power Laser that blinds anyone looking through the targeted optic. The system can operate in automatic, Semi-automatic or manual modes.

9. An example of a naval system can be found in the Royal Navy Dazzler found on some UK warships. The only details available are photographs.

HIGH ENERGY LASER SYSTEMS
10. The Laser is a very attractive alternative weapon system offering several advantages over conventional weapons. These are:
a. Almost zero time of flight.

b. The beam travels in a straight line.


11. However there are also limitations:

a. Very high-energy requirements.

b. Complex technology.

c. Expensive

12. Due to the classification of many of the HEL projects it is again difficult to get reliable information about each of the various systems. However their development can be traced through unclassified sources. The first hint of any such systems can be found in the late 1060’s and 1970’s, but the first major publicity of their existence came about with the US Strategic Defence Initiative SDI of the 1980’s. Recent years have produced much more open discussion with the emphasis being placed on Lasers being used purely as a defensive weapon to shoot down SCUD missiles. It is still a very sensitive area as recently witnessed with the widespread criticism of USA proposal to use Lasers as protection against ICBM’s.
13. Initial attempts at producing HEL weapons resulted in large devices with low power and poor beam quality. The beams were also degraded by atmospheric distortion, a phenomenon not overcome for many years with the introduction of adaptive optical systems. (Covered later in these notes). Early HEL employed gas lasers while more recent systems use chemical lasers to generate more power. Two examples of this are the Mid IR Advanced Chemical Laser (MIRACL) and the Chemical Oxygen Iodine Laser (COIL), both of which are used in present day systems. We shall now look at specific examples of Land and Airborne systems.
LAND BASED HEL
14. Developed initially as a naval initiative the US has developed the SeaLite 400 kW Laser that used IR and Visible sensors to track targets. It reportedly shot down a TOW ATGM in flight. In 1980 it was used to destroy a tethered and stationary UH-1 helicopter. Eventually funding was lost for this system but it was later resurrected as the Multi Purpose Chemical Laser (MPCL) producing the 1986 10 MW LATEX Laser.

15. In 1989 the SeaLite aiming and tracking system was used in conjunction with the MIRACL to produce the highest power, 2.2 MW Deuterium Fluoride, operational Laser. This is base at the High Energy Laser Systems Test Facility. (HELSTF) based at White Sands in the USA. This system has reportedly engaged a Vandal supersonic missile and shot down 5 Firebee drones.

16. In 1996 the US Army Nautilus project used the MIRACL at low power to shoot down a short-range rocket in flight. In 1997 it was reportedly fired at a satellite. The success of this project led to the forming of a joint US / Israeli project know as the Tactical High Energy Laser (THEL). This system, which is mobile, is designed to engage tactical battlefield weapons with a Deuterium Fluoride Laser. A fixed site demonstrator has been built that has demonstrated a capability to shoot down several ‘small’ Targets. However it has proven to be delicate, unreliable and requiring too much maintenance. An updated system, now called the Mobile THEL (MTHEL), is currently under development. The range of potential targets has been expanded and it is planned that each system, presently consisting of 3 units, will be reduced to one vehicle easily transportable by C-130. This reduction in size may be achieved by the use of a new solid-state Laser.

17. Additional projects in development by the US include an Army 10 kW solid-state Laser which they hope to develop to 100 kW operational system by 2006. The USA is also developing the airborne Advanced Tactical Laser. (ATL)
AIRBORNE HEL
18. There is much activity in the development of airborne Laser applications both as high power damage systems and as lower power non-lethal systems for use in IRCM. The US Army is developing the non-lethal HELSTAR system using a COIL similar in design to the highly publicised Airborne Laser Project. (ABL). Designed for helicopters, the HELSTAR is 50 – 70 kW in power and has a range of only a few kilometres.
19. The USA first trialed airborne Laser technology in the 1980’s with the creation of the Airborne Laser Laboratory (ALL). This converted KC-135 was fitted with a 10.6 micron system that successfully shot down 5 sidewinder missiles. It did however highlight the problem of how the atmosphere makes the Laser wavefront go out -of- phase with a resultant drop in power. This effect has now been overcome by the use of adaptive optics, basically a combination of computer controlled deformable mirrors, which transmit a shaped wavefront that becomes in-phase after transmission through the atmosphere. This technique was first developed to remove star scintillation caused by the variable refractive index of the atmosphere.

20. The ABL project uses a converted Boeing-747 equipped with a COIL plus 3 other low-power Lasers for tracking of the target. The system is designed to engage ICBM’s as they break cloud cover above their launch site. The coil can engage at ranges up to 450 nm and provides for 45 seconds to destroy the target, fairly slow in this phase of its flight, which has not had time to deploy decoys or multiple re-entry vehicle warheads. If the engagement is successful, there is an added bonus of the debris falling back upon the launch area. Space based Lasers are prohibited by international treaty which this system does not require as it is fired from within the atmosphere. The project should be completed by 2003 and operational by 2007.


SUMMARY

21. As it should be evident from these notes, there is evidence of many developments in the use of Laser weapons in a wide variety of applications. The technology now exists to create a Laser of low or high-power specifically designed to match a particular requirement or function. Lasers are capable of being used as low-power dazzle weapons, medium-power for IRCM applications or high power anti-missile systems.
22. Breakthroughs in solid state laser technology are resulting in successful projects such as the mobile THEL; directed energy weapons could be installed in aircraft by 2010 and be the future of precision strikes and defence against missiles.
23. The ABL is conducting evaluation trials (Nov 2002); AAR procedures are being evaluated and the IR targeting sensors monitored a US ballistic missile launch from a range of 300nm.