Sighting Systems in Small Arms
Research and development is being undertaken globally to enhance the reach, improve the resolution and reduce the weight of sights in order to provide a better edge to own side
Research and Development is being undertaken globally to enhance the reach, improve the resolution and reduce the weight of sights in order to provide a better edge to own side.
ASIGHT IS A DEVICE used to assist aligning or aim weapons, surveying instruments, or other items by eye. Sights can be a simple set or system of markers that have to be aligned together as well as aligned with the target (referred to as an iron sights on firearms). They can also be optical devices that allow the user to see the image of an aligned aiming point in the same focus as the target. These include telescopic sights and reflector (or ‘reflex’) sights. There are also sights that project an aiming point onto the target itself, such as laser sights.
At its simplest, a sight is typically composed of two components, front and rear aiming pieces that have to be lined up. Such sights can be found on many types of devices including weapons, surveying and measuring instruments, and navigational tools. On weapons, these sights are usually formed by rugged metal parts, giving these sights the name ‘iron sights’, a term relative to other weapon sights in that they are not optical or computing sights. On many types of weapons they are built-in and may be fixed, adjustable, or marked for elevation, windage, target speed, etc. They also are classified in forms of notch (open sight) or aperture (closed sight). These types of sights can take considerable experience and skill in the user who has to hold a proper eye position and simultaneously focus on the rear sight, the front sight, a target at different distances, and align all three planes of focus.
A telescopic sight, commonly called a scope, is a sighting device that is based on an optical refracting telescope. They are equipped with some form of graphic image pattern (a reticle) mounted in an optically appropriate position in their optical system to give an accurate aiming point. Telescopic sights are used with all types of systems that require accurate aiming but are most commonly found on firearms, particularly rifles. Other types of sights are iron sights, reflector (reflex) sights, and laser sights. The optical components may be combined with optoelectronics to form a night scope.
Another type of optical sight is the reflector (or ‘reflex’) sight, a generally non-magnifying optical device that allows the user to look through a glass element and see a reflection of an illuminated aiming point or some other image superimposed on the field of view. These sights have been around for over 100 years and been used on all types of weapons and devices.
A collimator sight is a type of optical sight that allows the user looking into it to see an illuminated aiming point aligned with the device the sight is attached to regardless of eye position (with little parallax). Collimator sights are ‘blind’ sights; that is, they are used with both eyes open while one looks into the sight, with one eye open and moving the head to alternately see the sight and then at the target, or using one eye to partially see the sight and target at the same time. Collimator sights are a relatively old idea, being used in many forms for almost 100 years. They are also referred to as collimating sights or ‘occluded eye gun sight’ (OEG).
The laser has in most firearms applications been used as a tool to enhance the targeting of other weapon systems. For example, a laser sight is a small, usually visible-light laser placed on a handgun or a rifle and aligned to emit a beam parallel to the barrel. Since a laser beam has low divergence, the laser light appears as a small spot even at long distances; the user places the spot on the desired target and the barrel of the gun is aligned (but not necessarily allowing for bullet drop, windage, distance between the direction of the beam and the axis of the barrel, and the target mobility while the bullet travels).
Most laser sights use a red laser diode. Others use an infrared diode to produce a dot invisible to the naked human eye but detectable with night vision devices. The firearms adaptive target acquisition module LLM01 laser light module combines visible and infrared laser diodes. In the late 1990s, green diode pumped solid state (DPSS) laser sights (532 nm) became available. Modern laser sights are small and light enough for attachment to the firearms.
Red Dot Sight
A red dot sight is a common classification for a type of non-magnifying reflector sight for firearms, and other devices that require aiming, that gives the user an aim point in the form of an illuminated red dot. A standard design uses a red light-emitting diode (LED) at the focus of collimating optics which generates a dot style illuminated reticle that stays in alignment with the weapon the sight is attached to regardless of eye position (nearly parallax free). They are considered to be fast acquisition and easy to use gun sights for target shooting, hunting, and in police and military applications. Aside from firearm applications, they are also used on cameras and telescopes. On cameras they are used to photograph flying aircraft, birds in flight, and other distant, quickly moving objects. Telescopes have a narrow field of view and therefore are often equipped with a secondary ‘finder scope’ such as a red dot sight.
Holographic Weapon Sights (HWS)
Holographic weapon sights use a laser transmission hologram of a reticle image that is recorded in three-dimensional space onto holographic film at the time of manufacture. This image is part of the optical viewing window. The recorded hologram is illuminated by the collimated light of a laser diode built into the sight. The sight can be adjusted for range and windage by simply tilting or pivoting the holographic grating. To compensate for any change in the laser wavelength due to temperature, the sight employs a holography grating that disperses the laser light by an equal amount but in the opposite direction as the hologram forming the aiming reticle. Like the reflector sight, the holographic sight is not ‘parallax free’, having an aim-point that can move with eye position. This can be compensated for by having a holographic image that is set at a finite distance with parallax due to eye movement being size of the optical window at close range and diminishing to zero at the set distance (usually around a desired target range of 100 metres).
Since the reticle is a transmission hologram, illuminated by a laser shining
through hologram presenting a reconstructed image, there is no need for the sight ‘window’ to be partially blocked by a semi-silvered or dielectric dichroic coating needed to reflect an image in standard reflex sights. The optical window in a holographic weapon sight looks like a piece of clear glass with an illuminated reticle in the middle. The aiming reticle can be an infinitely small dot whose perceived size is given by the acuity of the eye. For someone with 20/20 vision, it is about one minute of arc. One drawback of a holographic sight is shorter battery life when compared to reflex sights that use LEDs, such as red dot sights. However, the holographic weapon sight is optically, electronically, and otherwise superior to red dot sights. The two types of sight differ in optical performance and construction.
The diopter is an aperture sight component used to assist the aiming of devices, mainly firearms, airguns and crossbows. It is found in particular as a rear sight element on rifles.
The diopter is in principle a height and sideways (elevation and windage) adjustable occluder with a small hole (aperture), and is placed close in front of the shooter’s aiming eye. Through this small hole the shooter can view the front sight component(s) and the intended target. The typical occluder used in target shooting diopters is a disc of about 2.5 cm (1 in) in diameter with a small hole in the middle.
The small diopter viewing opening ensures the shooter’s eye is very precisely and consistently centred behind the diopter sight. The diopter sight is easy to use and usually allows for very accurate aiming, because a relative long sighting line can be used.
Modern Assault Rifles
Most modern assault rifles in use have optical sights such as the red dot sights and diopter sights. Most of them can be fitted with a detachable scope mounts and night vision devices. Some examples are given below.
The Tavor TAR-21 assault rifle was developed by Israel Military Industries (IMI) back in the early 1990s. This weapon is simple, tough and versatile. It was adopted by Israel in 2006 and became a standard issue infantry rifle. This assault rifle has been exported to more than 20 countries. This weapon has a standard Picatinny-type rail and is compatible with various scopes or night vision systems. It comes with red-dot sight as standard.
The Steyr AUG (universal army rifle) was designed in Austria. It has been adopted by Austrian Army back in 1977. When it first appeared it was considered to be revolutionary in many respects. Immediately after its introduction the AUG became popular. The original model has integral 1.5x magnification sight. It is designed for up to 300 m range. Also there are back-up iron sights for emergency use. Newer models lack integral sights, but have Picatinny-type rail and can be fitted with any sights.
The G36 assault rifle has been designed by Heckler & Koch to replace the G3 assault rifle in service with the Bundeswehr. Since 1995 the G36 is a standard issue infantry rifle with the German armed forces. This weapon became an export success. It has been exported to more than 40 countries around the world. Sights are built into the carrying handle. A standard German Army rifle has a dual sight system. It consists of one 3.5x magnification scope, for long-range accurate
shooting and one 1x magnification red dot sight above it, for close ranges.
The AK-74M with the Russian Army can be fitted with collimator and optical sights to ensure fast and precise targeting with improved combat efficiency. The standard optical sight is the 1P29 universal sight with 4x magnification. It has a field of vision of 80.
SIG SG 550 is the assault rifle with the Swiss Army. Sighting equipment consists of a flip-up front sight and adjustable rear diopter. It has a sighting range of 400 m. Every rifle can be fitted with a detachable scope mount. Swiss Army rifles are often used with 4x magnification scope. Current production models are available with a Picatinny-type rail and can mount various scopes, red dot or night vision sights.
India’s Excalibur rifle fires a standard NATO 5.56x45 mm ammunition. It features high ruggedness for battlefield engagements and is lighter to handle. It is well suited for low intensity conflicts and close quarter combat situations. The rifle is also ergonomically designed with folding butt and Picatinny rails for mounting optical/electronic devices.
Companies Dealing with Sighting Systems
Aimpoint AB is a supplier of electro-optical sighting systems including passive red dot collimator sight, laser device, fire control systems and mounts. The company strengthened its position as market leader when it was awarded the first multi-year contract ever for red dot sights by the US Army in 1997. Since then, Aimpoint has continued to deliver large quantities of sights to the US Army, French Army, US Air Force, US SOCOM, Swedish Army, Norwegian Army, Dutch Army, Danish Army and Italian Army.
Optex Systems. US-based optical sighting systems manufacturer Optex Systems has secured a contract to supply new periscopes for the US Army. Under the terms of the $8,41,000 deal, the company will supply an undisclosed number of periscopes to be installed aboard the army’s Abrams tanks. The periscopes will feature glass and plastic laser protection for soldiers’ eyes.
Photonic. is a globally active contractor for optical and opto-electronic instruments since 1986, whose optical products enjoy an excellent reputation in the field of infantry and artillery weapon systems. The well-known manufacturer of reliable and highly efficient optical instruments has developed a unique sighting system to lay muzzle-loaded indirect fire weapons such as 60mm mortars.
Thales Optics. The Sight Unit Small Arms, Trilux (or SUSAT) is a 4x with telescopic sight with tritium-powered illumination, utilised at dusk or dawn. The full name of the current model is the SUSAT L9A1. The SUSAT sight was developed in the United Kingdom by Royal Armaments Research Development Establishment (RARDE) and is manufactured by United Scientific Instruments and Avimo, now known as Thales Optics.
Trijicon has led the industry in the development of superior any-light aiming systems since the company’s founding in 1981. World-renowned for its innovative applications of tritium and advanced fibre optics, Trijicon manufactures the most advanced riflescopes and sights for tactical and sporting applications.
A US Army soldier checks through his rifle scope for any suspicious activity at an observation point in Iraq