What Is A "Forward Looking Infrared Imaging System?" | .uk

Anatholy Medvev, Leningrad Russia

• Forward looking infrared (FLIR) cameras, typically used on military and civilian aircraft, use an imaging technology that senses infrared radiation. The sensors installed in forward-looking infrared cameras—as well as those of other thermal imaging cameras—use detection of infrared radiation, typically emitted from a heat source, to create a "picture" assembled for video output. They can be used to help pilots and drivers steer their vehicles at night and in fog, or to detect warm objects against a cooler background. The wavelength of infrared that thermal imaging cameras detect differs significantly from that of night vision, which operates in the visible light and near-infrared ranges (0.4 to 1.0 µm). There are two basic ranges of infrared; long-wave infrared and medium-wave infrared. The long-wave infrared (LWIR) cameras, sometimes called "far infrared", operate at 8 to 12 µm and can see heat sources, such as hot engine parts or human body heat, a few miles away, but longer-distance viewing is made more difficult because the infrared light is absorbed, scattered, and refractedby the air and water vapor. Some long-wave cameras require their detector to be cryogenically cooled, typically for several minutes before use, although moderately sensitive infrared cameras are produced that do not require cryogenic cooling. Many thermal imagers including some forward looking infrared cameras are uncooled such as some LWIR Enhanced Vision Systems (EVS).Cameras which operate in the 3 to 5 m range are called medium-wave infrared (MWIR) and can see almost as well, as those frequencies suffer less from water-vapor absorption, but generally require a more expensive sensor array and cryogenic cooling. Many camera systems use digital image processing to improve the image quality. infrared imaging sensor arrays often have wildly inconsistent sensitivities from pixel to pixel, due to limitations in the manufacturing process. To remedy this, the response of each pixel is measured at the factory, and a transform, most often linear, maps the measured input signal to an output level.Some companies offer advanced "fusion" technologies that blend a visible-spectrum image with an infrared-spectrum image to produce better results than a single-spectrum image alone. According to a method for forming a forward looking infrared system an imaging lens system is arranged along an optical path in combination with a detector array to focus collimated radiation upon the detector array. The detector array subtends the field of view along a first direction. A reimaging afocal system is incorporated along the optical path to provide collimated radiation to the imaging lens system and a scanning device is positioned between the reimaging afocal system and the imaging lens system to vary the field of view along a second direction in order to provide a two dimensional image.

  GOTETI MVSR KRISHNA, TADEAPLLIGUDEM,ANDHRA PRADESH INDIA