REVISION MILITARY

LAZRBLOC™ LASER EYE PROTECTION WHITEPAPER

BACKGROUND
Lasers or LASER is Light Amplification by Stimulated Emission of Radiation. Lasers are generated in a variety of wavelengths of light, most commonly in the visible and near infrared (NIR) sections of the electromagnetic spectrum. Visible and NIR lasers present a unique hazard to the human eye. Since the human eye is composed of tissues that are vulnerable to lasers. Even low levels of laser of laser energy in the visible or NIR spectra can cause permanent eye injury or loss of sight. The danger, however, is often hidden – lasers in the NIR spectrum cannot be seen by the human eye, and without proper protection, the eyes can be severely damaged (burned). The retina of the eye can be permanently damaged and a severe burn of the cornea may produce a loss of vision even after healing.

Laser technology has expanded to use by military and law enforcement personnel worldwide, where devices have become commonplace in many operational environments and forces. Lasers have also been used maliciously; targeting civilian and military aircraft. The number of illegal laser incidents reported to the FAA has risen by nearly 100% from 3,894 reported incidents in 2014 to 7,703 incidents reported in 2015. The risk of injury to military, law enforcement, aviators, and civilians is historically high. Revision Military has developed the following whitepaper to educate military, law enforcement, and aviators about the dangers that lasers present, types and classes of laser equipment, current and future laser protective options, and finally, Revision’s technologies and capabilities to combat the growing need for advanced laser eye protection (LEP) solutions.

LASER USAGE AND INCIDENCES
Military forces around the world use lasers for a wide variety of purposes. Range finders, target designators, target illuminators, anti-missile systems, guided munitions, and weapon system neutralizing technology all use lasers to function. Increasingly, hand-held lasers are used at check-points for crowd control and to temporarily blind or disorient those exhibiting aggressive behavior. Additionally, large, multi-national companies such as Northrop Grumman, Raytheon and Boeing are currently developing and expecting to field the next generation laser systems – 100kW laser weapons which have enough power to knock mortars and rockets out of the sky.

There are also a growing number of accounts relating to the criminal misuse of lasers. A former commercial pilot was quoted as saying, “Laser attacks had been a concern to airlines for almost 10 years, and attacks “seemed to be on the increase”.2 The FAA is concerned about the risk to pilots, aircraft, and civilians. They have maintained data of reported laser illuminations of aircraft since 2004. In just ten years, the number of laser illuminations reported daily has increased by over 1900%. In 2015 the number of reported laser illuminations increased to 21.1 per day, up from 10.7 per day in 2014. The sinister use of lasers even extends and has been reported in the sports world. In 2008, a well known British soccer player was the victim of a laser attack during a highly publicized soccer match, resulting in fines to the opposing team. Additionally, lasers have been used against law enforcement. Violent use of lasers has been reported at riots all over the world, including in the United States, Canada, Ireland, Thailand, Greece, Egypt, and Italy, among others. 3 In many documented cases, laser accidents are often the result of the “friendly” misuse of a laser weapon. The U.S. Army’s Medical Research Detachment at Brooks Air Force Base tracks the circumstances, laser system and injury related to injuries sustained with soldiers operating in a military capacity. Many documented cases result from lack of training, experience or knowledge about the laser producing equipment or the dangers that lasers present. In fact, the U.S. military disclosed that as recently as March 30, 2009, an American soldier was blinded in one eye and three others required medical evacuation out of Iraq in a series of laser “friendly fire” incidents.4 Military forces around the world are increasingly aware of the growing threat and dangers that lasers pose and the need for effective force protection. Specifically, Revision is currently under contract or has provided laser protective lenses to the U.S. Army, U.S. Air Force, Canadian Department of National Defence (DND), the German Bundeswehr, Belgium Ministry of Defence (MoD), and several other military forces, Based on the growing use and incidence of laser injuries, the U.S. Army published a laser lens technical bulletin in January 2006 entitled “Control of Hazards to Health From Laser Radiation” which provided a detailed study on laser producing equipment, hazard evaluations, accident reporting and logistics and safety support.5 The bulletin is a comprehensive resource and is published for public use with unlimited distribution.

There are also a growing number of accounts relating to the criminal misuse of lasers. A former commercial pilot was quoted as saying, “Laser attacks had been a concern to airlines for almost 10 years, and attacks “seemed to be on the increase”.2 The FAA is concerned about the risk to pilots, aircraft, and civilians. They have maintained data of reported laser illuminations of aircraft since 2004. In just ten years, the number of laser illuminations reported daily has increased by over 1900%. In 2015 the number of reported laser illuminations increased to 21.1 per day, up from 10.7 per day in 2014. The sinister use of lasers even extends and has been reported in the sports world. In 2008, a well known British soccer player was the victim of a laser attack during a highly publicized soccer match, resulting in fines to the opposing team. Additionally, lasers have been used against law enforcement. Violent use of lasers has been reported at riots all over the world, including in the United States, Canada, Ireland, Thailand, Greece, Egypt, and Italy, among others.

In many documented cases, laser accidents are often the result of the “friendly” misuse of a laser weapon. The
U.S. Army’s Medical Research Detachment at Brooks Air Force Base tracks the circumstances, laser system and injury related to injuries sustained with soldiers operating in a military capacity. Many documented cases result from lack of training, experience or knowledge about the laser producing equipment or the dangers that lasers present. In fact, the U.S. military disclosed that as recently as March 30, 2009, an American soldier was blinded in one eye and three others required medical evacuation out of Iraq in a series of laser “friendly fire” incidents.4

Military forces around the world are increasingly aware of the growing threat and dangers that lasers pose and the need for effective force protection. Specifically, Revision is currently under contract or has provided laser protective lenses to the U.S. Army, U.S. Air Force, Canadian Department of National Defence (DND), the German Bundeswehr, Belgium Ministry of Defence (MoD), and several other military forces, Based on the growing use and incidence of laser injuries, the U.S. Army published a laser lens technical bulletin in January 2006 entitled “Control of Hazards to Health From Laser Radiation” which provided a detailed study on laser producing equipment, hazard evaluations, accident reporting and logistics and safety support.5 The bulletin is a comprehensive resource and is published for public use with unlimited distribution.

TYPES AND CLASSES OF LASER EQUIPMENT
The various types of commercial, industrial, and military lasers are divided by class to describe the capabilities of a laser system to produce injury. The various types of lasers are classified as the following:

Class 1 – This class is eye-safe under all operating conditions.

Class 1M – This class is safe for viewing directly with the naked eye, but may be hazardous to view with the aid of optical instruments. In general, the use of magnifying glasses increases the hazard from a widely-diverging beam (eg LEDs and bare laser diodes), and binoculars or telescopes increase the hazard from a wide, collimated beam (such as those used in open-beam telecommunications systems).

Class 2 – These are visible lasers. This class is safe for accidental viewing under all operating conditions. However, it may not be safe for a person who deliberately stares into the laser beam for longer than 0.25 s, by overcoming their natural aversion response to the very bright light.

Class 2M – These are visible lasers. This class is safe for accidental viewing with the naked eye, as long as the natural aversion response is not overcome as with Class 2, but may be hazardous (even for accidental viewing) when viewed with the aid of optical instruments, as with class 1M. Radiation in classes 2 and 2M is visible, but can also contain an invisible element, subject to certain conditions.

Classes 1M and 2M broadly replace the old class 3A under IEC and EN classification. Prior to the 2001 amendment there were also lasers which were Class 3B but were eye-safe when viewed without optical instruments. These lasers are Class 1M or 2M under the current Classification system.

Class 3R – Radiation in this class is considered low risk, but potentially hazardous. The class limit for 3R is 5x the applicable class limit for Class 1 (for invisible radiation) or class 2 (for visible radiation). Hence CW visible lasers emitting between 1 and 5 mW are normally Class 3R. Visible class 3R is similar to class IIIA in the US regulations.

Class 3B – Radiation in this class is very likely to be dangerous. For a continuous wave laser the maximum output into the eye must not exceed 500mW. The radiation can be a hazard to the eye or skin. However, viewing of the diffuse reflection is safe.

Class 4 – This is the highest class of laser radiation. Radiation in this class is very dangerous, and viewing of the diffuse reflection may be dangerous. Class 4 laser beams are capable of setting fire to materials onto which they are projected.

Any laser product of a given Class may contain ’embedded’ lasers which are greater than the Class assigned to the product, but in these cases engineering controls (protective housings and interlocks) ensure that human access to radiation in excess of product Class is not possible. Notable examples of this are CD and DVD players which are Class 1 laser products while containing Class 3R or Class 3B lasers and laser printers which are Class 1 laser products but contain Class 4 embedded lasers.6

Another comprehensive laser resource is the Medical NBC Battlebook published by the U.S. Army Center for Health Promotion and Preventive Medicine (USACHPPM). Developed to address operational health concerns in environments where Nuclear, Biological, and Chemical (NBC) threats exist, the Medical NBC Battlebook includes information regarding the use and hazards of laser weapons and equipment as well as recognition and prevention of laser injuries. 7

Based upon the requests that Revision receives from its international customer base, the following information from the Medical NBC Battlebook is not specific to the United States. While this information is published by the U.S. Military, Revision’s international customer’s often request laser protective solutions which protect against the same or similar laser threats and wavelengths as published in the Medical NBC Battlebook detailed in the following tables.

Table 1: Common Laser Wavelengths, as published in the Medical NBC Battlebook, and the section of the electromagnetic spectrum in which the wavelengths reside, as well as the typical operation of the laser; pulse-train, pulsed, and continuous wave (CW).

Table 2: Army Field Laser Systems, as published in the Medical NBC Battlebook, which lists the type of laser device and its physical description.

Image 1 indicates laser sources on the battlefield as they relate to the UV, Visible and Infrared spectrum.

Table 3: Listing of Army Fielded Laser Systems, which includes the nominal ocular hazard distance, in meters, the suggested optical density of laser eye protection with and without optics, and their laser classification.

CURRENT LASER EYE PROTECTION TECHNOLOGIES
In order to combat the wide range of current and emerging laser threats, the ideal laser protective lens offers:

  • High luminous transmittance in the visible spectrum Effective attenuation of laser wavelengths
  • Excellent color recognition
  • Ability to provide broadband protection against tunable or mutable laser lines
  • Injection molded ballistic grade substrate containing durable and robust protection technology Angle independence allowing use on complex shaped substrates
  • Compatible with protective and anti-fog coatings Low cost, scalable for mass production technology

To protect against lasers, the two most widely used laser protection technologies in protective eyewear are dyes and dielectric coating

Laser protective dye:

A laser protective dye is a pigment, often added to an injection molded plastic.  When lasers hit a lens, the dye  will absorb the light, which effectively blocks the energy from reaching the eye. Laser protective dyes are widely used due to their relative low cost. Dyes are often designed to block a range of wavelengths (broadband) or a single wavelength (narrowband); however their absorbance typically tapers off from a peak absorbance wavelength. Depending on the design of the dye, the luminous transmittance is affected by how quickly or slowly the absorbance changes. Additionally, most dyes will tint a lens, which can have adverse effects on color recognition. However, laser absorbers are constantly improving.  Combinations and concentrations of dyes can  be carefully optimized to provide the perfect balance of narrow or broadband laser protection, luminous transmittance, and color recognition.

Dielectric coating:

This relatively new technology for ballistic eyewear is still subject to scientific research. A dielectric coating is actually made of a fine stack of layers with different reflective properties. A dielectric coating acts as a negative interference filter. Currently, laser protective dielectric coatings are limited in their use due to their very high cost (for similar applications, a lens with dielectric coatings is roughly 10 to 20 times more expensive than a lens made using laser protective dye). Mass production continues to challenge the dielectric coating industry, while the dielectric coatings are also easily scratched and generally require additional scratch-resistance protection. However, research continues to find coatings that provide abrasion resistance.

Despite the cost and fragile nature of dielectric coating technology, the benefits are very exciting; promising high luminous transmittance, excellent protection, and improved color recognition. Dielectric coatings have the potential to combine broadband protection and high visible light transmission in a single lens. This will have meaningful application in the military environment, where maintaining situational awareness is paramount. However, until advancements are made in durability, cost, and manufacturing, dielectric coatings will be relegated to applications where exposure to harsh environments is limited.

FUTURE TECHNOLOGIES
As lasers continue to be developed for use in equipment and tactics, there is a constant need to research and develop improved laser protection technologies. The foreseeable future identifies a need for the following technologies:

Tuneable laser protection to counteract tuneable lasers which can change their operational wavelength and to protect against multiple laser threats.

Optical switches and limiters which activate only in the presence of specific laser wavelengths. This allows the protection to stay completely clear until laser protection is needed and allows for excellent visual light transmission.

PROTECTIVE CAPABILITY OF LASER LENSES
The protective capability of LEP is often described as optical density (OD). To determine the protective capability of a “laser lens”, its optical density (OD) at a specific wavelength is measured. The OD determines the amount of laser energy which is blocked (by reflection or absorption) by the LEP. Optical density is measured on a base 10 logarithmic scale, so an increase by 1 point in OD represents an additional 90% reduction in transmittance. Table 3 provides a correlation between optical density, transmittance, and laser attenuation.


Table 4: The relationship between optical density (OD), transmittance, and absorbance

Several variables affect the protective capabilities of LEP, however the most common are dye concentrations, coating thickness, and lens thickness. By altering the concentrations and thicknesses, the OD of a lens can be changed. Most LEP for use outside of a laboratory provides OD2 to OD4 protection depending on the use. Protection from pulse lasers or from lab grade lasers may require protection beyond OD4.

PHOTOPIC AND SCOTOPIC* VISION AND LASER PROTECTION

Unlike standard (non-laser) protective lenses, the difference between photopic and scotopic light transmission in a dye-based laser lens may be extreme. Photopic light transmission is the perceived transmittance of light under daylight conditions, while scotopic light transmission is the perception under low light conditions. The reason for the measurement of light transmittance under these two conditions is that the human eye perceives light differently in light and dark environments. The peak luminous efficacy of the eye in photopic conditions is about 555nm. However, in dark scotopic conditions, this peak shifts down to about 507nm. For this reason, if LEP is designed to block the very common green laser at 532nm, it has serious implications for the luminous transmittance under photopic and scotopic conditions. Figure 1 shows luminous transmittance curve of a very common green laser absorber in relationship to the scotopic and photopic luminous efficacy of the eye. As the chart indicates, there is very little scotopic luminous transmittance compared to photopic luminous transmittance. When designed LEP it is important to consider the environmental conditions in which it will be used, so that acceptable luminous transmittance is achieved.


Figure 1: Transmission curve of a 532nm absorbing lens and the luminous efficacy under photopic and scotopic conditions.

REVISION LAZRBLOC LASER EYE PROTECTION
Revision Revision Military’s LazrBloc technology offers a variety of ballistic LEP options to impact, and laser protection in a diversity of hostile situations (Figure 1, 2, 3, and 4).


Figure 2: Riot police attacked by a laser, a tactic increasingly used by protesters to distract and blind law enforcement dispersing crowds and vehicles in the path of travel.


Figure 3: Laser mounted to a military vehicle for the purpose of dispersing crowds and vehicles in the path of travel. Reflections can be harmful. Visible and NIR lasers are often used in military applications.


Figure 4: An aircraft being illuminated by a green laser, filling the cockpit with harmful visible radiation.


Figure 5: Pilots run the risk of injury and the inability to control their aircraft during laser attacks. Green lasers are very commonly used against aircraft.

Revision’s laser protective solutions have been tested and work seamlessly with visual augmentation equipment such as night vision goggles and provide the required OD. In order to verify the optical density or amount of laser light which is blocked (by reflection or absorption), Revision has tested laser lenses in its state-of-the-art research and development laboratory and has certified many of the lenses at 3rd party testing factilities.

Revision Military currently offers the following LazrBloc™ Laser Protective Lenses:


Additionally, Revision Military has developed samples of other laser protective lenses, demonstrating the ability to be responsive to customer needs and provide custom solutions.

REVISION MILITARY’S MANUFACTURING FACILITY
In summer 2008, Revision Military began operation of its new lens manufacturing facility within the company’s U.S. Headquarters in Essex Junction, Vermont.

Revision, producing purpose-built military eye protection with operations in Vermont since 2004, invested in the company’s future capability by creating a 17,000 square foot, environmentally controlled clean room for lens production. The new facility employs cutting edge technology, giving Revision in-house, “just-in-time” lens production and coating capability for its military and tactical clients.

This operation is capable of producing millions of high quality, military grade lenses each year and, importantly, all laser protective lenses will be produced in Revision’s Vermont facility. The quality of the in-house manufacturing facility, coupled with outstanding laboratories and quality assurance testing facilities, ensures that Revision provides lenses which far exceed the toughest military standards while maintaining positive control over production.


Figures 6,7: Revision’s computer controlled injecting molding line is in an environmentally controlled room

Revision is molding its high quality military eyewear lenses using Nissei NEX environmentally friendly, all electric molding machines. Nissei is a world leader in injection molding, designing machines that meet and exceed the most critical optical manufacturing requirements.

After molding, each part is transferred to the customized coating line, which has been purchased from the world’s foremost expert in lens coating equipment. The versatile coating line can coat lenses by either dip or flow coat methods which gives Revision unmatched capability to apply the perfect coating for a given application. Figure 8,9,10: Coatings can be applied by dip and flow techniques on a single run by bar coded selection. All parts are visually inspected for defects and imperfections. All information

Figure 8,9,10: Coatings can be applied by dip and flow techniques on a single run by bar coded selection. All parts are visually inspected for defects and imperfections.

SUMMARY
Revision is committed to providing a full complement of high-impact, laser protective solutions for our customer’s use in a wide variety of military and tactical environments. Revision’s spectrum of LazrBlock offerings and its ability to conduct in-house R&D, molding, and coating enables Revision Military to meet specific and diverse laser protective requirements, including single, multi-band, or broadband protection.

Depending upon the product or program requirements, Revision estimates that it will take 12-14 weeks to conduct a feasibility study and produce custom laser protective solutions for common laser threats. Less common solutions may take longer depending upon the ballistic, laser and light transmission requirements.

In addition to dye additive laser lenses, Revision is currently working with world-class laser technology suppliers to develop the next generation of laser protective lens technology. When available and production ready, it is Revision’s intention to integrate this technology with our best-in-class ballistic and optics products to offer our customers the next generation of high-impact, laser protective eyewear.

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