A sight or sighting device is any
device used to assist in precise
visual alignment (i.e. ''aiming'') of weapons,
surveying
Surveying or land surveying is the technique, profession, art, and science of determining the land, terrestrial Plane (mathematics), two-dimensional or Three-dimensional space#In Euclidean geometry, three-dimensional positions of Point (geom ...
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
Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...
illuminators on some
night vision devices, as well as
augmented or even
virtual reality
Virtual reality (VR) is a Simulation, simulated experience that employs 3D near-eye displays and pose tracking to give the user an immersive feel of a virtual world. Applications of virtual reality include entertainment (particularly video gam ...
-enabled
digital camera
A digital camera, also called a digicam, is a camera that captures photographs in Digital data storage, digital memory. Most cameras produced today are digital, largely replacing those that capture images on photographic film or film stock. Dig ...
s ("smart scopes") with software
algorithm
In mathematics and computer science, an algorithm () is a finite sequence of Rigour#Mathematics, mathematically rigorous instructions, typically used to solve a class of specific Computational problem, problems or to perform a computation. Algo ...
s that produce
digitally enhanced target images.
Iron sights
At its simplest, a sight typically has two components, front and rear aiming pieces that have to be lined up. Sights such as this can be found on many types of devices including weapons,
surveying
Surveying or land surveying is the technique, profession, art, and science of determining the land, terrestrial Plane (mathematics), two-dimensional or Three-dimensional space#In Euclidean geometry, three-dimensional positions of Point (geom ...
and measuring instruments, and navigational tools.
On weapons, these sights are usually formed by rugged metal parts, giving them the name "
iron sights", as distinct from optical or computing sights. On many types of weapons they are built-in and may be fixed, adjustable, or marked for
elevation
The elevation of a geographic location (geography), ''location'' is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational equipotenti ...
,
windage, target speed, etc.
They are also classified in forms of notch (open sight) or aperture (closed sight). These types of sights can require considerable experience and skill, as the user has to hold proper eye position and simultaneously focus on the rear sight, the front sight, and a target, all at different distances, and align all three ''planes of focus''.
Optical sights

Optical sights use
optics
Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of optical instruments, instruments that use or Photodetector, detect it. Optics usually describes t ...
that give the user an enhanced image with an aligned aiming point or pattern (also called a
reticle)
superimposed onto the target image, preferably at the same
focal plane.
Telescopic sights
A
telescopic sight is a
refracting telescope
A refracting telescope (also called a refractor) is a type of optical telescope that uses a lens (optics), lens as its objective (optics), objective to form an image (also referred to a dioptrics, dioptric telescope). The refracting telescope d ...
equipped with some form of
referencing pattern (
reticle) mounted in an optically appropriate position in the optical system to give an accurate aiming point. Telescopic sights are used on a wide range of devices including
guns,
surveying
Surveying or land surveying is the technique, profession, art, and science of determining the land, terrestrial Plane (mathematics), two-dimensional or Three-dimensional space#In Euclidean geometry, three-dimensional positions of Point (geom ...
equipment, and even as sights on larger telescopes (called a
finderscope).
Reflector sights

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 have been used on all types of weapons and devices.
Reflector sights were first used as a weapon sight in German aircraft towards the end of
World War I
World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...
. Over the years they became more sophisticated, adding lead computing gyroscopes and electronics (the
World War II
World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
Gyro gunsight)
radar range finding and other flight information in the 1950s and 1960s, eventually becoming the modern
head-up display.
Other types of optical sights
*
Collimator sight
*
Holographic weapon sight
A holographic weapon sight or holographic diffraction sight is a non-magnification, magnifying gunsight 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. ...
*
Laser sight
*
Red dot magnifier used in conjunction with a non-magnified optical sight
List of sights
There are many types of sighting devices. They can be fixed, mechanical, optical,
computational, or a mixture of all of these attributes.
*
Bombsight
*
Collimator sight
*
Diopter sight
*
Globe sight
*
Head-up display
*
Holographic weapon sight
A holographic weapon sight or holographic diffraction sight is a non-magnification, magnifying gunsight 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. ...
*
Iron sight
*
Laser sight
*
Reflector sight
**
Gyro gunsight
**
Red dot sight
*
Telescopic sight
*
Thermal weapon sight
*
Night vision device
*
Fire-control system
See also
*
Gun laying
*
Predicted impact point
*
Tritium radioluminescence
Tritium radioluminescence is the use of gaseous tritium, a radioactive isotope of hydrogen, to create visible light. Tritium emits electrons through beta decay and, when they interact with a phosphor material, light is emitted through the proces ...
Notes
External links
The story of how all Miramar Tomcat squadrons got the funds to purchase riflescopes to attach to the HUD of their F-14 fighter jets
{{DEFAULTSORT:Sight (Device)
Firearm components
Optical devices
Artillery components
Surveying instruments
es:Visor