Infrared Camera Characterization
Many different types of infrared (IR) detector technology are now commercially available and the physics of their operation has been described in an earlier chapter. IR imagers are classified by different characteristics such as scan type, detector material, cooling requirements, and detector physics. Thermal imaging cameras prior to the 1990s typically contained a relatively small number of IR photosensitive detectors. These imagers were known as cooled scanning systems because they required cooling to cryogenic temperatures and a mechanical scan mirror to construct a two-dimensional (2D) image of the scene. Large 2D arrays of IR detectors, or staring arrays, have enabled the development of cooled staring systems that maintain sensitivity over a wide range of scene flux conditions, spectral bandwidths, and frame rates. Staring arrays consisting of small bolometric detector elements, or microbolometers, have enabled the development of uncooled staring systems that are compact, lightweight, and low power (see Figure 4.1).