The vision thing, on the helmet.
The invention of portable night vision technology such as helmet-mounted night vision systems has opened a new dimension in modern warfare. They have allowed those who possess such systems to 'own the night' and remove the cover of darkness as the camouflage of their enemies. Helmet-mounted night vision is indispensable for any army or special forces unit contemplating operations, and these days, whoever owns the night can often rule the day.
Night vision systems are very much a product of the post-Second World War environment. Night operations were difficult and dangerous for all the belligerents during World War II and while night vision technology was actively researched by both the Axis and Allied powers, sufficient miniaturisation would not have been achieved to allow any mounting onto an individual infantry soldier's helmet. Fast-forward sixty years and television pictures filmed in the eerie green glow of the night vision camera are commonplace and audiences are now accustomed to watching footage of combat operations performed under the cover of darkness.
Night Vision Principles
Traditional systems work on a simple principle: they detect light emissions in the 'near-infrared' band. As a comparison the human eye sees light in the wavelengths of 0.4 to 0.7 micrometers, whereas night vision systems can detect light in the range of one micrometer. Essentially, the sensor detects ambient light and amplifies it. During night time this ambient light can come from starlight or moonlight and it is this light that is reflected from objects and displayed by the system.
Image intensifier goggles absorb photons of ambient light that hit a detector plate located in an intensifier tube. This detector plate will then emit a cascade of electrons and these then collide with a phosphor screen. The collision of these electrons produces light at the point where they strike the screen and this subsequently creates an image. So why is the image usually green? Simple: most systems use a green phosphor screen because the human eye sees this colour particularly clearly.
The military generally uses passive systems. They are passive in the sense that they use the ambient light described above as their source of illumination. Active systems are available but these require a light source, usually infrared, to illuminate the surroundings. However, infrared can be detected; and for this reason passive systems are more attractive for military applications. That said infrared-based active systems have developed a niche for civilian security camera applications. Most modern systems are not without active illumination systems. For instance, night vision goggles often have a small infrared light which can be shone downwards to read a map.
The earliest passive systems arrived during the Vietnam War. These systems were put into the bracket of so-called 'generation-one' capabilities. They were large, depended on good moonlight coverage to work, and would provide light amplification of around 1000 times the ambient levels. Compared to modern generation-three (gen-three) systems, these early goggles often suffered from image distortion.
Gen-two systems could take the light amplification to around 2000 times more than the ambient level, and with this the quality of the image improved along with the overall reliability of the designs. These systems began to appear around the late 1960s and early 1970s and could see the environment in light conditions that were equivalent to one-quarter of the illumination provided by a full moon. One of the first notable gen-two systems was ITF's AN/PVS-5 Night Vision Goggle (NVG) system.
The technological quantum leap has come with the gen-three systems. These amplify light up to 50,000 times the ambient levels. Gen-three systems have also seen a huge increase in service life. These designs now have a life expectancy of up to 10,000 hours, compared to the 2000 hours of the first generation and the 4000 hours of the second.
The beauty of early systems, such as the AN/PVS-5 design, lies in their versatility. These goggles can equip everyone from infantry soldiers to drivers and platoon leaders: and they can be used in either a helmet-mounted or a hand-mounted fashion. They also have a built-in active infrared system for very short-range illumination.
ITT manufactures the AN/PVS-5 and AN/PVS-7. The latter are regularly seen on the helmets of soldiers based in Iraq, although they earned their spurs in Operation Desert Storm eleven years earlier. They will eventually replace the AN/PVS-5 systems in US Marine Corps service following a 2005 contract to this effect. One of the key benefits provided by the AN/PVS-7 system over earlier designs is their light weight: 540 grams vs. the 850 for the AN/PVS-5: a load savings that significantly reduces fatigue. As with the AN/PVS-5 system, the -7s have a close-range infrared light.
Northrop Grumman is the other American brand leader in the helmet-mounted night vision system market. The company produces the M963 system, which has integrated infrared light source for short-range illumination. The goggles have been designed not only for dismounted soldiers, but also for night time driving. The N963 goggles are powered by conventional AA-size batteries helping to reduce weight. They also have an automatic brightness control.
Moreover, the company builds an M966 four-times magnification goggle unit. These are designed for night-time surveillance and as well as being fitted to an infantryman's helmet, they can also be used as a hand-held monocular system, or mounted on a tripod. The M961 goggle system takes the magnification a step further, providing six-times image intensification, but at a light weight of 1.5 kg
Northrop Grumman's binocular M953 provides the fidelity that aviator systems afford to the foot soldier. Not only can the goggles be used in dismounted operations, but they have also been designed with amphibious missions and driving in mind. The M953 can be submerged in up to 20 m (66 ft) of water.
ITT meanwhile produces the AN/PVS14, which unlike the AN/PVS-5/-7, is a monocular design. This means that while it can attach to the users' helmet, it also has the capability to be attached to a weapon sight. Unlike the AN/PVS-5/-7 designs, the AN/PVS-14 is a third generation device which can provide five-times magnification when used with optional, attachable lenses. This makes the design especially useful for reconnaissance and observation operations, where standoff distance is always welcome.
American special forces are equipped with Northrop Grumman's M983 monocular system, which can be used in either a helmet-mounted, weapon-mounted or hand-held capacity. The company designed the M983 product to also be fully compatible with a standard reflex photo or video camera--a handy addition to night time surveillance or reconnaissance operations. Furthermore, the company also builds the monocular M914 system which is as versatile as the M983, but which can provide three- or five-times image magnification.
One of the latest United States Army acquisitions is the ITT AN/PSQ-20 Enhanced Night Vision Goggles (ENVG) design. This is a third-generation product intended to replace the AN/PVS-7/-14. The AN/PSQ-20 can be used either on its own or with rifle-mounted laser-sights The ENVG combines existing gen-three technology with thermal imaging sensors. Like image intensifiers, thermal imagers use a simple technique. All objects emit a heat signature and the hotter the temperature, the brighter the image appears on screen. ENVG use these two techniques since night vision is great at seeing things in the dark, but still requires an ambient light source, even if it is just starlight. The thermal imaging system provides extra vision in conditions where the ambient light source is so minimal that it cannot be detected by the intensifier. This also avoids the need to use infrared illumination as the light source. Where the ambient light is insufficient, the thermal imaging allows the user to see with sufficient clarity.
ITT also produces the AN/PVS-23, a binocular based on the AN/AVS-6 NVGs originally designed for pilots. These goggles have an infrared illuminator that can either be used for spot or flood illumination to light up a small area. One of the advantages of the AN/PVS-23 is that its binocular design allows the user to see an independent image through each tube, rather than types that use a single lens where the image is then viewed through binoculars. The system can be either helmet-mounted or removed and used as a pair of binoculars.
In terms of other third-generation systems, ITT builds the dual-tube binocular MV-14BG which provides good depth perception and is thus particularly useful for troops driving at night. The MV-14BG system can be used in either a helmet-mounted configuration or as binoculars.
The binoculars can be detached from one another and used separately or in conjunction with a camera or weapon sight. Moreover, the goggles are waterproof down to 20 metres.
O'Gara of Cincinnati, Ohio manufacturers the AN/PVS-21; a design popular with American Special Forces. Following an order in November 2006 the US Marine Corps will be equipped with what the company calls a 'significant number' of these systems. The AN/PVS-21 can be used in either binocular or monocular configuration and features an integral 'head-up display'. This allows the user to see a number of different imagery sources, including video transmission, thermal imaging or even Global Positioning System data.
The display of a number of imagery sources onto a visor is already commonplace in military aviation; however, delivering similar capabilities to the infantry soldier will go a long way to increasing situational awareness. It also provides a taste of the imagery capabilities which may appear in several of the 'Future Soldier' system-of-system programmes earmarked for service entry over the next decade. In the same year that O'Gara sold its AN/PVS-21 design to the US Marine Corps; it also secured a contract from the British Ministry of Defence. This system is also in service with the Canadian and Italian militaries.
Bushnell builds the lightweight 1 x 20 first-generation NVGs. Weighing 510 grams, these goggles are some of the lightest of their kind. They are joined by the Centurion Systems Multitask 1.5 x 24 CS44056 Dep Super Gen Night Vision monocular. This system can be either hand-held or helmet-mounted or also be attached to a camera to allow the recording of night vision footage. The Night Phantom dual-tube binocular is a third-generation system that can be helmet-mounted or head-mounted and features an adapter to allows it to be fitted to the Mich (Modular Integrated Communications Helmet), which is replacing the US Personnel Armor System Ground Troop helmet.
The American specialist N-Vision Optics produces the G-15 HMNV system which claims particularly good depth perception. Depth perception is particularly important as it allows the user to see a clearer three-dimensional image without the picture appearing as a two-dimensional TV-style image. Like the AN/PVS-21, this system has a dual-tube binocular design. The G-15 can be worn as a helmet-mounted system, detached and used as binoculars or alternatively separated into monoculars which can be hand-held, helmet-mounted, fixed on a camera or mounted on a weapon. The G-15 system includes short-range infrared illumination and is waterproof down to two metres.
N-Vision builds the NVP-140 second-generation, single-tube, rugged binocular which can withstand up to 5Gs of shock. Its sleight 450-grams allows it to be worn for long periods. A flip-lock mechanism allows it to be quickly detached for use as hand-held binoculars. Night Vision of the USA also makes a system that can be converted into variable-range binoculars. The company's USVN-221G design is water resistant and features dazzle protection. Optional lenses allow the binoculars to have x3 magnification.
For many years, the Russians have excelled at night vision technology and Russian companies offer many robust designs. One example is the ONV NVG design built by Lomo, which can be used either helmet-mounted or as hand-held binoculars. The Belarussian SV-23 design is a first-generation NVG system, weighs 70 grams and its aluminium construction provides good shock resistance. An infrared illuminator is included, and optional lenses allow the system to be converted into binoculars with up to x4.5 magnification. Push-button controls let the user switch on the in-built infrared illumination.
Away from Russia, the GNV-2 is built by Night Lights Vision of South Africa. This second-generation system can provide a high-resolution image across the 40[degrees] field-of-view and has a built-in dazzle protection system that prevents the NVGs from being damaged by sudden light flashes.
With a range of first-, second- and third-generation systems on the market, helmet-mounted night vision developers are turning their thoughts to what technologies we might see in future systems. Presently, systems use digital data derived from the ambient light as it enters the tube, which is then converted into analogue imagery by the tube for display to the user. Allowing night vision goggles to display a digital signal would help reduce weight and size.
We have already seen a glimpse of sensor fusion via the AN/PSQ-20 ENVG design which utilises both thermal and intensified imaging to enhance the users' situational awareness. While this technology is expensive (standard military-grade NVGs cost in the region of $ 2500 per unit, the ENVG system is projected to cost around $ 8000 per unit), mass production and technological advances may make NVG systems more affordable.
One glimpse of the future was seen at the Ausa Winter Symposium and Exhibition 2007 in Florida: Rockwell Collins showcased what the company calls its 'Future Force Warrior Headgear System (FFWHS). The design uses fused imagery but does away with a goggle design. This is replaced by an image intensification camera fusing both the NV and IR imagery and which is fitted into an Advanced Combat Helmet and then displayed on the soldier's monocular display. Like the ENVG system, the FFWHS is designed to provide the soldier with a range of information such as GPS or targeting information derived from a command and control network, along with thermal and infrared imagery. The major challenge with the present system is its weight, which is around 2.3 kg when the helmet is included. The system is yet to enter production and is still very much a technology demonstrator.
Other technologies on the horizon include 'Colorpath'. Developed by Tenebraex of Boston, Massachusetts, Colorpath provides the user with colour night vision converted from the imagery derived from a standard NVG tube. There are many advantages with such technology. The company's website lists these as: "Wound assessment, camouflage detection; vehicle and personnel identification, marking identification, map reading". In fact, they are almost endless. Such technology could go some way into making the murky green world appear more like daylight with all of the visual benefits that the warrior enjoys when operating in sunlight. While technology is moving in the right direction in terms of image fusion, colour NVG technology and digital displays; the real challenge will be in making this technology light and rugged enough for the warfighter to use, and affordable enough for the procurement chiefs to buy.
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|Date:||Apr 1, 2008|
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