A holographic weapon sight or holographic diffraction sight is a non- magnifying gunsight that allows the user to look through a glass optical window and see a

holographic Holography is a technique that allows a wavefront to be recorded and later reconstructed. It is best known as a method of generating three-dimensional images, and has a wide range of other uses, including data storage, microscopy, and interfe ...

reticle A reticle or reticule, also known as a graticule or crosshair, is a pattern of fine lines or markings built into the eyepiece of an optical device such as a telescopic sight, spotting scope, theodolite, optical microscope or the electronic v ...

image superimposed at a distance on the

field of view The field of view (FOV) is the angle, angular extent of the observable world that is visual perception, seen at any given moment. In the case of optical instruments or sensors, it is a solid angle through which a detector is sensitive to elec ...

. The

hologram Holography is a technique that allows a wavefront to be recorded and later reconstructed. It is best known as a method of generating three-dimensional images, and has a wide range of other uses, including data storage, microscopy, and interf ...

of the reticle is built into the window and is illuminated by a laser diode.

History

The first-generation holographic sight was introduced by EOTech—then an ERIM subsidiary—at the 1996 SHOT Show,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 fictitious business name. Registering the fictitious name with ...

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

hunting Hunting is the Human activity, human practice of seeking, pursuing, capturing, and killing wildlife or feral animals. The most common reasons for humans to hunt are to obtain the animal's body for meat and useful animal products (fur/hide (sk ...

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, when Vortex introduced the Razor AMG UH-1 into the market as a competing product. As Vortex introduced the Gen II model on mid July, 2020 which later replaced the original UH-1.

Design

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

three-dimensional space In geometry, a three-dimensional space (3D space, 3-space or, rarely, tri-dimensional space) is a mathematical space in which three values ('' coordinates'') are required to determine the position of a point. Most commonly, it is the three- ...

onto

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 ray (optics), rays, and therefore will spread minimally as it propagates. A laser beam is an archetypical example. A perfectly collimated light beam, with no beam divergen ...

of a laser diode built into the sight. The sight can be adjusted for range and

windage In aerodynamics, firearms ballistics, and automobiles, windage is the effects of some fluid, usually air (e.g., wind) and sometimes liquids, such as oil. Aerodynamics Windage is a force created on an object by friction when there is relative m ...

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

(0.3 mrad). 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 sightline, lines of sight and is measured by the angle or half-angle of inclination between those two lines. Due to perspective (graphica ...

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 laser diode 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> The Aimpoint CompM5s red dot sight has an expected battery life of around 8,000 to hours (1 to 5 years) depending on the 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