A holographic weapon sight or holographic diffraction sight is a non- magnifying

gunsight A sight is an aiming device used to assist in visually aligning ranged weapons, surveying instruments or optical illumination equipments with the intended target. Sights can be a simple set or system of physical markers that have to be align ...

that allows the user to look through a glass optical window and see a holographic reticle image superimposed at a distance on the field of view. The hologram of the reticle is built into the window and is illuminated by a

laser diode The laser diode chip removed and placed on the eye of a needle for scale A laser diode (LD, also injection laser diode or ILD, or diode laser) is a semiconductor device similar to a light-emitting diode in which a diode pumped directly with ...

History

The first-generation holographic sight was introduced by

EOTech EOTECH is an American company that designs, manufactures, and markets electro-optic and night vision products and systems. The company is headquartered in Plymouth, Michigan. They produce holographic weapon sights for small arms that have be ...

—then an ERIM subsidiary—at the 1996

SHOT Show The SHOT Show , which is an acronym for "Shooting, Hunting and Outdoor Trade Show", is an American annual trade show for the shooting sports, hunting, outdoor recreations and firearm manufacturing industries. The show is owned and sponsored b ...

,Jane's international defence review: IDR.: Volume 34, page 76 under the

trade name A trade name, trading name, or business name, is a pseudonym used by companies that do not operate under their registered company name. The term for this type of alternative name is a "fictitious" business name. Registering the fictitious name w ...

HoloSight by Bushnell (with whom the company was partnered with at the time), initially aiming for the civilian sport shooting and

hunting Hunting is the human activity, human practice of seeking, pursuing, capturing, or killing wildlife or feral animals. The most common reasons for humans to hunt are to harvest food (i.e. meat) and useful animal products (fur/hide (skin), hide, ...

market. It won the Optic of the Year Award from the Shooting Industry Academy of Excellence. EOTech was the only company that manufactured holographic sights until early 2017 (possibly January 2017), when

Vortex In fluid dynamics, a vortex ( : vortices or vortexes) is a region in a fluid in which the flow revolves around an axis line, which may be straight or curved. Vortices form in stirred fluids, and may be observed in smoke rings, whirlpools in ...

introduced the Razor AMG UH-1 into the market as a competing product.

Design

Holographic weapon sights use a laser transmission hologram of a reticle image that is recorded in

three-dimensional space Three-dimensional space (also: 3D space, 3-space or, rarely, tri-dimensional space) is a geometric setting in which three values (called ''parameters'') are required to determine the position of an element (i.e., point). This is the informa ...

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 A collimated beam of light or other electromagnetic radiation has parallel rays, and therefore will spread minimally as it propagates. A perfectly collimated light beam, with no divergence, would not disperse with distance. However, diffraction ...

of a

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. 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 1

minute of arc A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The n ...

(0.3

mrad The Barrett MRAD (Multi-role Adaptive Design) is a bolt-action sniper rifle designed by Barrett to meet the requirements of the SOCOM PSR. The MRAD is based on the Barrett 98B and includes a number of modifications and improvements. The Barre ...

). Holographic sights can be paired with " red dot magnifiers" to better engage farther targets.

Parallax error

Like the reflector sight, the holographic sight is not "

parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby object ...

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

due to eye movement being the size of the optical window at close range and diminishing to zero at the set distance (usually around the target range of 100 yards).

Compared to reflector sights

Light transmission

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 such as in standard reflex sights. Holographic sights therefore have the potential for better light transmission than reflector sights.

Manufacturing costs

Holographic sights are considerably more expensive than red dot sights, due to their complexity as well as there being only two manufacturers of holographic sights.

Size

Holographic sights are generally bulkier than reflex sights and require a rifle to mount, while red dot sights have been made small enough to fit handguns.

Battery life

Holographic sights have shorter battery life when compared to reflex sights that use LEDs, such as red dot sights. The

in a holographic sight uses more power and has more complex driving electronics than a standard LED of an equivalent brightness, reducing the amount of time a holographic sight can run on a single set of batteries compared to a red dot sight (around 600 hours for typical holographic sights, compared to sometimes up to tens of thousands of hours for red dot sights). For example, the Vortex Razor AMG UH-1 holographic sight has been quoted as having an expected battery life of 1,000 to 1,500 hours (1½ to 2 months) on medium setting,Vortex Razor AMG UH-1 , Holographic Greatness , SOFREP
/ref> while the Aimpoint CompM5s red dot sight has an expected battery life of around 8000 to hours (1 to 5 years) depending on setting.Aimpoint - CompM5s
/ref>

References

External links

Red Dot Sights / Reflex Sights & Holosights Explained -Electronic Sights; A look at why they exist, how they work, and how you use them.
{{Firearms Firearm sights Optical devices