A sight based on the use of infra-red technology to produce a picture of the heat signature of an object against its background. It is a passive system which detects infra-red (IR) radiation emitted by the target and converts this into an electrical signal which can be used to create a visual image.
There are a number of materials which produce an electrical signal when exposed to IR radiation, but the most commonly used is Cadmium Mercury Telluride (CMT). This semiconductor material, with suitable doping, produces usable outputs in both the 3-5 and the 8-13 micron wavebands. With the CMT cooled to about -200 degrees Centigrade, particularly high sensitivity is achieved in the 8-13 micron waveband. Thus, when good picture quality is required, 8-13 microns has proved to be first choice for scanning TI systems, in which the detector is only briefly exposed at each picture point. Detectors operating in the 3-5 micron waveband will produce usable images at about -60 degrees Centigrade. Other materials, such as Indium Antimonide are also used in the 3-5 micron waveband.
Unlike other sights, which requires some ambient visible radiation, the thermal imager will function in complete darkness, enabling the operator to see various objects at distances of up to several kilometers.
The main component of the thermal imager is a thermal camera. The most known producers of thermal cameras are French SAGEM and THALES companies.
Sergyi Way
24.07.2006