Optical sights are optical lens assemblies used for aiming a gun. There are several basic types of products. Categories include telescopic sights, visible sights, and infrared sights.
Telescopic sights or rifle scopes have reticles and are specified according to optical magnification and objective lens diameter. For example, a 10 x 50 rifle scope denotes an optical sight with 10 times magnification and a 50-mm lens.
Visible sights such as pistol laser sights and rifle laser sights provide instant, visible target acquisition under even low-light conditions. Shooters can keep both eyes on the target, which is usually designated with a colored laser dot.
Infrared sights use thermal imaging technology and represent an alternative to night vision goggles. Specialty optical sights are also available.
Telescopic sights provide either fixed or variable magnification. Fixed magnification scopes are fixed focal length (FFL) devices. These optical sights do not provide manual or automatic zoom functions. Variable sights provide a relatively wide field of view, typically at lower magnification settings. Telescopic sights also differ in terms of reticles. Reticle choices include fine crosshair, duplex crosshair, German reticle, target dot, mil dot, circle, and range-finding. Complex reticle designs allow a shooter to estimate the range while compensating for variables such as bullet drop and cross winds. To prevent parallax-induced problems, telescopic optical sights may be equipped with special optical elements. These optical components project, in the same optical plane, a picture of the object in the crosshairs and a picture of an object at another distance. Visible sights and infrared sights are used by the U.S. military, homeland security, local police departments, and private security firms. Laser sights are visible optical sights that are designed to mount on grips, guide rods, and rails. These optical sights produce laser dots that can be seen hundreds of yards of away. Although most pistol laser sights and rifle laser sights project a red laser beam, products that produce a green beam are also available. Some visible sights are water-resistant and designed for rugged environments. In some cases, thermal goggles and mini infrared cameras are used with these optical sights. Devices are either handheld or helmet-mounted.