Editing Night vision (section)

==Night vision technologies==
[[File:Night vision.ogv|thumb|1974 [[US Army]] film about the development of military night vision technology]]

Night vision technologies can be broadly divided into three main categories: [[Image intensifier|image intensification]], active [[lighting|illumination]], and [[thermal imaging]]. Digital night vision is also emerging, which instead uses high sensitivity [[CMOS]] image sensors with a passthrough system.

===Image intensification===
{{Main|Image intensifier}}

This magnifies the amount of received photons from various natural sources such as [[starlight]] or moonlight. Examples of such technologies include night glasses and low light cameras. In the military context, Image Intensifiers are often called [[Low light level television|"Low Light TV"]] since the video signal is often transmitted to a display within a control center. These are usually integrated into a sensor containing both visible and IR detectors and the streams are used independently or in fused mode, depending on the mission at hand's requirements.<ref>{{Cite web |url=http://www.raytheon.com/media/sas/mts/ |title=Raytheon Multi-Spectral Targeting Systems (MTS) |access-date=2015-05-26 |archive-url=https://web.archive.org/web/20170903052528/http://www.raytheon.com/media/sas/mts/ |archive-date=2017-09-03 |url-status=dead }}</ref>

The image intensifier is a vacuum-tube based device (photomultiplier tube) that can generate an image from a very small number of photons (such as the light from stars in the sky) so that a dimly lit scene can be viewed in real-time by the naked eye via visual output, or stored as data for later analysis. While many believe the light is "amplified," it is not. When light strikes a charged [[photocathode]] plate, electrons are emitted through a vacuum tube and strike the microchannel plate. This causes the image screen to illuminate with a picture in the same pattern as the light that strikes the photocathode and on a wavelength the human eye can see. This is much like a [[CRT television]], but instead of color guns the photocathode does the emitting.

The image is said to become "intensified" because the output visible light is brighter than the incoming light, and this effect directly relates to the difference in passive and active [[night vision goggles]]. Currently, the most popular image intensifier is the drop-in [[ANVIS]] module, though many other models and sizes are available at the market. Recently, the US Navy announced intentions to procure a dual-color variant of the [[ANVIS]] for use in the cockpit of airborne platforms.<ref>{{Cite web |url=http://www.elbitsystems-us.com/sites/default/files/imported/airborne/hdts.pdf |title=Archived copy |access-date=2015-05-26 |archive-url=https://web.archive.org/web/20160304081443/http://www.elbitsystems-us.com/sites/default/files/imported/airborne/hdts.pdf |archive-date=2016-03-04 |url-status=dead }}</ref>

=== Digital night vision ===
Digital night vision relies on high sensitivity [[Back-illuminated sensor|back-illuminated]] [[CMOS]] image sensors, also sometimes called [[sCMOS]] (scientific CMOS). Their sensitivity can exceed the sensitivity of the human eye.<ref name="a897">{{cite web |title=Security Camera Image Sensor Technology STARVIS™/ STARVIS 2 |url=https://www.sony-semicon.com/en/technology/security/index.html |access-date=2025-02-02 |website=Sony Semiconductor Solutions Group}}</ref> These sensors can be head-mounted in night vision goggles and [[Telescopic sight|rifle scopes]], but are also used in [[security camera]] systems, [[astronomy]], and [[microscopy]].<ref name="x644">{{cite web |title=What is a Scientific CMOS Camera- Oxford Instruments |url=https://andor.oxinst.com/learning/view/article/scmos-technology-what-is-scmos |access-date=2025-02-02 |website=Oxford Instruments}}</ref> Infrared illumination can be used, but is not necessary for their functionality.

=== Active illumination ===
[[File:M3 Sniperscope.jpg|thumb|[[USMC]] M3 Sniperscope assembled on a [[M1 Carbine|M3 Carbine]]. Introduced during the [[Korean War]], it was an early active infrared night vision equipment powered by a large 12 volt battery that was carried in a rubberized canvas backpack.]]
[[File:M60 PattonMediumTank.jpg|thumb|An [[M60 tank]] with an infrared searchlight mounted on the cannon.]]

Active illumination couples imaging intensification technology with an active source of illumination in the [[near infrared]] (NIR) or shortwave infrared (SWIR) band. Examples of such technologies include low light cameras.

Active infrared night-vision combines infrared illumination of spectral range 700–1,000&nbsp;nm (just over the [[visible spectrum]] of the human eye) with sensors or [[charge-coupled device|CCD]] cameras sensitive to this light. The resulting scene, which is apparently dark to a human observer, appears as a monochrome image on a normal display device.<ref>{{cite web |title=YouTube mp3 indir |url=https://mp3video.org/ |website=mp3video.org}}</ref> Because active infrared night-vision systems can incorporate illuminators that produce high levels of infrared light, the resulting images are typically higher resolution than other night-vision technologies.<ref>{{cite web|url=http://www.irinfo.org/articles/03_01_2007_grossman.html |title=Thermal Infrared vs. Active Infrared: A New Technology Begins to be Commercialized |url-status=dead |archive-url=https://web.archive.org/web/20100117205639/http://www.irinfo.org/articles/03_01_2007_grossman.html |archive-date=January 17, 2010 }}</ref><ref>{{Cite web |url=http://www.extremecctv.com/products_video.php?vid=19 |title=Extreme CCTV Surveillance Systems |access-date=2008-01-24 |archive-url=https://web.archive.org/web/20080405225223/http://www.extremecctv.com/products_video.php?vid=19 |archive-date=2008-04-05 |url-status=dead }}</ref>  Active infrared night vision is now commonly found in commercial, residential and government security applications, where it enables effective night time imaging under low-light conditions. However, since active infrared light can be detected by night-vision goggles, there can be a risk of giving away position in tactical military operations.

Laser range gated imaging is another form of active night vision which utilizes a high powered pulsed light source for illumination and imaging. Range gating is a technique which controls the laser pulses in conjunction with the shutter speed of the camera's detectors.<ref>{{cite journal |author1=J. Bentell |author2=P. Nies |author3=J. Cloots |author4=J. Vermeiren |author5=B. Grietens |author6=O. David |author7=A. Shurkun |author8=R. Schneider | title = FLIP CHIPPED InGAaS PHOTODIODE ARRAYS FOR GATED IMAGING WITH EYE-SAFE LASERS  | url = http://www.couriertronics.com/docs/Xenics/Gated%20Imaging.pdf }}</ref> Gated imaging technology can be divided into ''single shot'', where the detector captures the image from a single light pulse, and ''multi-shot'', where the detector integrates the light pulses from multiple shots to form an image. One of the key advantages of this technique is the ability to perform [[target recognition]] rather than mere detection, as is the case with thermal imaging.

=== Thermal vision ===
{{see also|Thermographic camera|Forward-looking infrared}}
[[Thermal imaging]] detects the temperature difference between background and foreground objects. Some organisms are able to sense a crude thermal image by means of special organs that function as [[bolometer]]s. This allows thermal [[infrared sensing in snakes]], which functions by detecting thermal radiation.

[[Thermographic camera|Thermal imaging cameras]] are excellent tools for night vision. They detect [[thermal radiation]] and do not need a source of illumination. They produce an image in the darkest of nights and can see through light fog, rain, and smoke (to a certain extent). Thermal imaging cameras make small temperature differences visible. They are widely used to complement new or existing security networks, and for night vision on aircraft, where they are commonly referred to as "FLIR" (for "forward-looking infrared"). When coupled with additional cameras (for example, a visible spectrum camera or SWIR) multispectral sensors are possible, which take advantage of the benefits of each detection band's capabilities. Contrary to misconceptions portrayed in the media, thermal imagers cannot "see" through solid objects (walls, for example), nor can they see through glass or acrylic, as both these materials have their own thermal signature and are opaque to long wave infrared radiation.