Night vision
A night vision device is an optical instrument that enhance light on low light situations using image intensifier unit. Night vision systems most often are used by the law enforcement personnel or military, but are available also to civilian market for hunters, wildlife and astronomy enthusiasts and so on. NVG – night vision device consists from image intensifier tube, a protective and in most cases water resistant housing, and some type of mounting system. Many of devices also include interchangeable objectives, diode or laser infrared illuminators, and telescopic lenses.
Night vision devices found their first use in World War II, and came into general use by military during the Vietnam War. The technology has enhance greatly since first devices available, leading to several image intensifiers “generations” of night vision equipment with each time performance increasing and price decreasing.
Generation 0 (GEN 0)
They were active infrared devices, using a large infrared light source to illuminate targets. Although being developed by AEG starting in 1935 and provided to German army in 1939, first time battle usage they found on German tanks and infantry weapons in the end of Word War II.
Ferro 51 GEN 0 binoculars with infrared light source
Ferro 51 GEN 0 binoculars with infrared light source, developed from the companies AEG, De Oude Delft und Eltro (Zeiss – Group) in 1950′s and used by German and Swiss army forces. To activate this device you have to push one of the top buttons, the infrared high tension scope will be activated and receive invisible infrared light and the view is lighted. After a few time if the lighted view is going dawn, you have to push one of the buttons again.
Generation 1 (GEN 1)
First generation passive devices are introduced during the Vietnam and Afghanistan wars. These are an adaptation of earlier active GEN 0 technology, but they rely on ambient light instead of an infrared light source. GEN 1 image intensifiers produce a light amplification of around 1000x so to function properly they require moonlight.
Military adopted multistage, most often 3 stage GEN1 systems for their usage into viewing devices and rifle scopes, but are quite bulky and heavy, but can amplify light from 20’000x till 50’000x which make them useful for military application without showing up personnel position via active infrared light. In most cases low image resolution, distortion at the edges of view and heavy construction force developing more compact and lightweight systems like GEN 2.
Russian NSPU 1PN34 3 stage gen 1 rifle scope with accesories
Starlight technology Russian made 3 stage GEN1 cascade NSPU 1 PN34 rifle scope for all main personal weapons like AK variants, PKM machine guns, RPG propelled rocket launchers and SVD sniper rifles. Shown with accessories box which include some filters, ballistic cams, rechargeable batteries, transportation bag and case. Note the weight – 2,2 kg in battle and 3,5 kg in march conditions.
Generation 2 (GEN 2)
Second gen devices featured an improved night vision image intensifier tube which utilize micro channel plate (MCP) with an S-25 photocathode, and as result user get in a much brighter image, especially around edges of the viewable lens. This improvements leads to increased illumination in low ambient light environments, such as moonless or cloudy nights. In most cases light amplification for general second generation tubes are around 20000x. Also improved were image resolution and reliability.
Later development tubes with in GEN II technology has brought tactical characteristics of GEN II+ devices which are equipped with better optics, advanced aka SuperGen tubes, improved resolution and signal-to-noise ratio into the range of GEN III ones, which has complicated the reasonable comparison.
Early AN/PVS-7 with head mount
The AN/PVS-7 is the one of the most recognized night vision device in the world. It’s single image intensifier tube, bi-ocular configuration provides an excellent performance to cost ratio and features all needed user-friendly controls, built in IR illuminator, internal low battery and IR indicators. Standard PVS7 set equipment includes headgear, sacrificial window, demist shields, lens cleaning paper, neck strap, and soft carrying case. With the use of optional accessories, AN/PVS-7 can be configured for various mission requirements.
Generation 3 (GEN 3)
Third generation night vision systems maintain the micro channel plate (MCP) from Gen II, but now use a photo cathode made with expensive gallium arsenide, which further improves image intensifier tube resolution. Also in addition, the micro channel plate is coated with an ion barrier film for increased tube life so on such systems it can be up to 20’000 hours. The light amplification is also improved to around 30000 – 50000x.
PEQ AN/AVS-6 night vision googles
Water proof and nitrogen purged, these formidable Gen 3 night vision rifle goggles withdraw even harshest conditions. Built with the latest US made Generation 3 Pinnacle technology image intensifiers they are are rugged, yet light weight. It is the perfect tool for military personnel, law enforcement and professional varmint hunters.
Generation 4 (GEN 4)
Although the recent increased performance associated with the GEN-III OMNI-VII components is impressive, the US Army Night Vision and Electronic Sensors Directoratethe US Army has not yet authorized the use of the name GEN-IV for these components.
GEN-III OMNI-VII devices can differ from standard Generation 3 image intensifiers in two important ways. First, it’s an automatic gated power supply system regulates the photo cathode voltage, allowing the night vision device to instantaneously adapt to often changing light conditions. The second improvement is a removed or greatly thinned ion barrier, which decreases the amount of electrons that are usually rejected by the Standard GEN III micro channel plate, hence resulting in less image noise and the ability to operate with a luminous sensitivity at 2850K of only 700, compared to operating with a luminous sensitivity of at least 1800 for GEN III type image intensifiers. The disadvantage to a thin or removed ion barrier is the overall decrease in image intensifer tube life from a theoretical 20,000 hrs mean time to failure (MTTF) for Gen III type, to 15,000 hrs MTTF for GEN IV type. However, this is largely negated by the low numbers of image intensifier tubes that reach 15,000 hrs of operation before replacement.
It is important to note that while the consumer market classifies this type of system as “Generation 4″, the United States military describes these systems as Generation 3 Autogated tubes (GEN-III OMNI-VII). Moreover, as auto gating power supplies can now be added to any previous generation of night vision, ‘auto gating’ capability does not automatically class the devices as a GEN-III OMNI-VII, as seen with the XD-4. Another point to note is that any postnominals appearing after a Generation type (ie: Gen II +, Gen III +) does not change the generation type of the device, but instead indicates an advancement(s) over the original specification’s requirements.