Night-vision device
A night vision device usually consists of an image intensifier tube, a protective housing, and an optional mounting system.
Consequently, though they are commonly used by military and law enforcement agencies, night vision devices are available to civilian users for applications including aviation, driving, and demining.
The Sperber FG 1250 ("Sparrow Hawk"), with a range of up to 600 m, had a 30 cm infrared searchlight and an image converter operated by the tank commander.
Their image-intensifier tubes used an anode and an S-1 photocathode, made primarily of silver, cesium, and oxygen, and electrostatic inversion with electron acceleration produced gain.
This was bulky, needing an external power pack generating 7,000 volts, but saw limited use with amphibious vehicles of 79th Armoured Division in the 1945 crossing of the Rhine.
Although some were sent to India and Australia for trials before the end of 1945, by the Korean War and Malayan Emergency the British were using night vision equipment supplied by the United States.
[12] Early examples include: After World War II, Vladimir K. Zworykin developed the first practical commercial night-vision device at Radio Corporation of America, intended for civilian use.
Examples: Later advances brought GEN II+ devices (equipped with better optics, SUPERGEN tubes, improved resolution and better signal-to-noise ratios), though the label is not formally recognized by the NVESD.
[24] Third-generation night-vision systems, developed in the late 1980s, maintained the MCP from Gen II, but used a gallium arsenide photocathode, with improved resolution.
These switches are rapid enough that they are not detectable to the human eye and peak voltage supplied to the night vision device is maintained.
[30] Autogating also enhances the Bright-Source Protection (BSP), which reduces the voltage supplied to the photocathode in response to ambient light levels.
Automatic Brightness Control (ABC) modulates the amount of voltage supplied to the microchannel plate (rather than the photocathode) in response to ambient light.
[30] These modulation systems also help maintain a steady illumination level in the user's view that improves the ability to keep "eyes on target" in spite of temporary light flashes.
These functions are especially useful for pilots, soldiers in urban environments, and special operations forces who may be exposed to rapidly changing light levels.
[30][31] OMNI, or OMNIBUS, refers to a series of contracts through which the US Army purchased GEN III night vision devices.
[34] GEN III OMNI V–IX devices developed in the 2000s and onward can differ from earlier devices in important ways: The consumer market sometimes classifies such systems as Generation 4, and the United States military describes these systems as Generation 3 autogated tubes (GEN III OMNI V-IX).
It is calculated using the number of line pairs per millimeter that a user can detect multiplied by the image intensifier's signal-to-noise (SNR) ratio.
By 2001, the United States federal government concluded that a tube's generation was not a determinant performance factor, obsoleting the term as a basis of export regulations.
ITAR regulations specify that US-made tubes with a FOM greater than 1400 are not exportable; however, the Defense Technology Security Administration (DTSA) can waive that policy on a case-by-case basis.
[43][45] Out of Band (OOB) refers to night vision technologies that operate outside the 500-900 nm NIR (near infrared) frequency range.
[68] Examples: Foveated night vision (F-NVG) uses specialized WFoV optics to increase the field of view through an intensifier tube.
A night-vision contact lens prototype places a thin strip of graphene between layers of glass that reacts to photons to brighten dark images.
[81] The Sensor and Electron Devices Directorate (SEDD) of the US Army Research Laboratory developed quantum-well infrared detector (QWID).
The Corrugated QWID (CQWID) broadens detection capacity by using a resonance superstructure to orient more of the electric field parallel so that it can be absorbed, although cryogenic cooling between 77 K and 85 K is required.
QWID technology may be appropriate for continuous surveillance viewing due to its claimed low cost and uniformity in materials but it has yet to enter commercial production.
Because, traditionally, night-vision systems capture side-by-side views from each spectrum, they can't produce identical images unlike films applied to ordinary glasses.
The PN stands for pritsel nochnoy (Russian: прицел ночной), meaning "night sight", and the xx is the model number.
Supported weapons include the AK family, sniper rifles, light machine guns and hand-held grenade launchers.
