CollimatorA collimator is a device which narrows a beam of particles or waves. To narrow can mean either to cause the directions of motion to become more aligned in a specific direction (i.e., make collimated light or parallel rays), or to cause the spatial cross section of the beam to become smaller (beam limiting device). The English physicist Henry Kater was the inventor of the floating collimator, which rendered a great service to practical astronomy. He reported about his invention in January 1825.
Sight (device)A sight or sighting device is any device used to assist in precise visual alignment (i.e. aiming) of ranged weapons, surveying instruments, aircraft equipment or optical illumination equipments 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.
FinderscopeA finderscope is an accessory sighting device used in astronomy and stargazing, typically a small auxiliary refracting telescope/monocular mounted parallelly on a larger astronomical telescope along the same line of sight. The finderscope usually has a much smaller magnification than the main telescope, thus providing a larger field of view, useful for manually pointing (a.k.a. "slewing") the main telescope into a roughly correct direction that can easily place a desired astronomical object in view when zooming in.
Collimator sightA 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). They are also referred to as collimating sights or "occluded eye gunsight" (OEG). The basic layout of a collimator sight is a closed tube with a lens at its open end and a luminous reticle mounted near the closed end at the focus of the lens, creating an optical collimator.
Telescopic sightA telescopic sight, commonly called a scope informally, is an optical sighting device based on a refracting telescope. It is equipped with some form of a referencing pattern – known as a reticle – mounted in a focally appropriate position in its optical system to provide an accurate point of aim. Telescopic sights are used with all types of systems that require magnification in addition to reliable visual aiming, as opposed to non-magnifying iron sights, reflector (reflex) sights, holographic sights or laser sights, and are most commonly found on long-barrel firearms, particularly rifles, usually via a scope mount.
MilliradianA milliradian (SI-symbol mrad, sometimes also abbreviated mil) is an SI derived unit for angular measurement which is defined as a thousandth of a radian (0.001 radian). Milliradians are used in adjustment of firearm sights by adjusting the angle of the sight compared to the barrel (up, down, left, or right). Milliradians are also used for comparing shot groupings, or to compare the difficulty of hitting different sized shooting targets at different distances.
ReticleA reticle, or reticule also known as a graticule, 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 screen of an oscilloscope, to provide measurement references during visual inspections. Today, engraved lines or embedded fibers may be replaced by a superimposed on a screen or eyepiece.
Laser sight (firearms)A laser sight is a device attached or integral to a firearm to aid target acquisition. Unlike optical and iron sights where the user looks through the device to aim at the target, laser sights project a beam onto the target, providing a visual reference point. Although lasers in the visible part of the spectrum are most common, invisible infrared (IR) lasers may be used in conjunction with a night vision device. As they are offset from the barrel, laser sights need to be zeroed in, much like a conventional sight, so that the beam intercepts the point of impact at a chosen distance.
ParallaxParallax 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 half-angle of inclination between those two lines. Due to foreshortening, nearby objects show a larger parallax than farther objects, so parallax can be used to determine distances. To measure large distances, such as the distance of a planet or a star from Earth, astronomers use the principle of parallax.
Night-vision deviceA night-vision device (NVD), also known as a night optical/observation device (NOD), night-vision goggle (NVG), is an optoelectronic device that allows visualization of images in low levels of light, improving the user's night vision. The device enhances ambient visible light and converts near-infrared light into visible light which can be seen by the user; this is known as I2 (). By comparison, viewing of infrared thermal radiation is referred to as thermal imaging and operates in a different section of the infrared spectrum.
