Infrared imaging devices

(engineering) Any device which converts an invisible infrared image into a visible image.

Devices that convert an invisible infrared image into a visible image. The radiation available for imaging may be emitted from objects in the scene of interest (usually at the longer wavelengths called thermal radiation) or reflected. Reflected radiation may be dominated by sunlight or may be from controlled sources such as lasers used specifically as illuminators for the imaging device. The latter systems are called active, while those relying largely on emitted radiation are called passive. Active optical imaging systems were developed to achieve a nighttime aerial photographic capability, and work during World War 11 pushed such systems into the near-infrared spectral region. Development of passive infrared imaging systems came after the war, but only the advent of lasers allowed creation of active infrared imagers at wavelengths much longer than those of the photographic region. See also Infrared radiation; Laser.

Although developed largely for military purposes, infrared imaging devices have been valuable in industrial, commercial, and scientific applications. These range from nondestructive testing and quality control to earth resources surveys, pollution monitoring, and energy conservation. Infrared images from aerial platforms are used to accomplish “heat surveys,” locating points of excessive heat loss. Calibration allows association of photographic tones with values of apparent (that is, equivalent blackbody) temperatures. Dark areas are “colder” than light ones. See also Remote sensing.