Night vision device in the context of Telescopic sight

A sight or sighting device is any device used to assist in precise visual alignment (i.e. aiming) of weapons, surveying instruments, aircraft equipment, optical illumination equipment or larger optical instruments with the intended target. Sights can be a simple set or system of physical markers that serve as visual references for directly aligning the user's line of sight with the target (such as iron sights on firearms), or optical instruments that provide an optically enhanced—often magnified—target image aligned in the same focus with an aiming point (e.g. telescopic, reflector and holographic sights). There are also sights that actively project an illuminated point of aim (a.k.a. "hot spot") onto the target itself so it can be observed by anyone with a direct view, such as laser sights and infrared illuminators on some night vision devices, as well as augmented or even virtual reality-enabled digital cameras ("smart scopes") with software algorithms that produce digitally enhanced target images.

The Hughes/McDonnell Douglas/Boeing AH-64 Apache (/əˈpætʃi/ ə-PATCH-ee) is an American twin-turboshaft attack helicopter with a tailwheel-type landing gear and a tandem cockpit for a crew of two. Nose-mounted sensors help acquire targets and provide night vision. It carries a 30 mm (1.18 in) M230 chain gun under its forward fuselage and four hardpoints on stub-wing pylons for armament and stores, typically AGM-114 Hellfire missiles and Hydra 70 rocket pods. Redundant systems help it survive combat damage.

The Apache began as the Model 77 developed by Hughes Helicopters for the United States Army's Advanced Attack Helicopter program to replace the AH-1 Cobra. The prototype YAH-64 first flew on 30 September 1975. The U.S. Army selected the YAH-64 over the Bell YAH-63 in 1976, and later approved full production in 1982. After acquiring Hughes Helicopters in 1984, McDonnell Douglas continued AH-64 production and development. The helicopter was introduced to U.S. Army service in April 1986. The advanced AH-64D Apache Longbow was delivered to the Army in March 1997. Production has been continued by Boeing Defense, Space & Security. As of March 2024, over 2,700 Apaches have been delivered to the U.S. Army and 18 international partners and allies.

Photomultiplier tubes (photomultipliers or PMTs for short) are extremely sensitive detectors of light in the ultraviolet, visible, and near-infrared ranges of the electromagnetic spectrum. They are members of the class of vacuum tubes, more specifically vacuum phototubes. These detectors multiply the current produced by incident light by as much as 100 million times or 10 (i.e., 160 dB), in multiple dynode stages, enabling (for example) individual photons to be detected when the incident flux of light is low.

The combination of high gain, low noise, high frequency response or, equivalently, ultra-fast response, and large area of collection has maintained photomultipliers an essential place in low light level spectroscopy, confocal microscopy, Raman spectroscopy, fluorescence spectroscopy, nuclear and particle physics, astronomy, medical diagnostics including blood tests, medical imaging, motion picture film scanning (telecine), radar jamming, and high-end image scanners known as drum scanners. Elements of photomultiplier technology, when integrated differently, are the basis of night vision devices. Research that analyzes light scattering, such as the study of polymers in solution, often uses a laser and a PMT to collect the scattered light data.

1PN51-2 (Russian: 1ПН51-2) is the GRAU index for a Soviet designed passive night scope for the RPG-29 rocket launcher. 1PN is the GRAU index of night vision devices, where PN stands for Nochnoy Pritsel (Russian: Ночной прицел) meaning night sight.

The scope weighs 2.1 kg and measures 280 mm × 192 mm × 106 mm (length × height × width). It is thus more compact than the similar multi-model 1PN51 night vision scope.