Night Vision and Thermal Systems

Night vision

A night vision device is an optical instrument that enhance light on low light situations using image intensifier unit. Night vision systems primary are developed and used by the law enforcement personnel or military, but depending on each country restrictions are also often available to civilian market for hunters, wildlife and astronomy enthusiasts. NVG – night vision device consists from image intensifier tube, 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 additional telescopic lenses.

Night vision devices found their first real life use at the end of World War II, and came into general service for military operations during the Vietnam War. The technology has enhance greatly since first devices available, leading to several image intensifiers “generations” for night vision equipment. Each time new generation image intensifier is available to end users, it technical performance is 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 military in 1939, first time battle usage they found on German Panther tanks and infantry weapons in the last days 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 some time when the lighted view is become darker, you have to push buttons again.

Generation 1 (GEN 1)
First generation passive devices was 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 and to function properly they require artificial light like clear skies with stars or even better moonlight.

For military devices like night vision rifle scopes and various viewing devices was adopted multistage (most often in 3 stage configuration) GEN1 systems. Although they are are quite bulky and heavy, compared to single stage GEN1 image intensifiers, this multi stage devices can amplify ambient light in ranges from 20’000x till 50’000x which make them extremely useful for military and LEO applications as this technology devices do not require active infrared light which can expose personnel position to enemy forces. Regardless of high light intensification, this technology has some disadvantages like low image resolution, distortion at the edges of view, heavy and bulky construction, forcing 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 Warsaw pact 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 and compact night vision image intensifier tube which utilize micro channel plate (MCP) with an S-25 photocathode. As a result devices based on this technology have much better image resolution, especially around edges of the viewable area which greatly improve viewing and recognition range. Compact design compared to previous generation rifle scopes and viewers like monoculars and binoculars, along with increased ambient light amplification in low light environment, such as moonless or cloudy nights and tube lifespan (for average about 15’000 hours compared to about 1000 hours for Generation 1 image intensifiers) lead to fast spreading of Generation 2 technology.

Later development of GEN II technology intensifier tubes has brought in additional enhancements like improved resolution, better light amplification and signal-to-noise ratio. Due performance and overall characteristics, improved image intensifiers are named as Generation 2+ night vision image intensifiers. Top of the line Generation 2+ intensifiers can tightly challenge even with GEN III intensifiers.

Early AN/PVS-7 with head mount

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 with an excellent performance to cost ratio and features with all needed user-friendly controls like built in IR illuminator for extra low light conditions, 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 image intensifier maintain the micro channel plate (MCP) from Gen II, but additionally use a photo cathode made with expensive gallium arsenide, which greatly improves image intensifier tube resolution and light amplification abilities. Also in addition, the micro channel plate is coated with an thin ion barrier film for increased tube life which on Gen III based systems can extend 20’000 hours of actual usage. The light amplification is also improved to around 30000 – 50000x depending on tube.

PEQ AN/AVS-6 night vision googles

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 or just anyone who want bring night to day.

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 Directorate has not yet authorized the use of the name GEN-IV for these components.

GEN-III OMNI-VII devices differ from standard Generation 3 image intensifiers with two important changes. First, it’s an automatic gated power supply system regulates the photo cathode voltage, allowing the night vision device instantaneously adapt to often changing light conditions like urban or battlefield environment. 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 intensifier 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 at this moment can be added to any of 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.