Optical radiation detectors are transducers that transform optical radiant energy into a different form of energy that is more readily measured. Electrical energy is typically used for this purpose, as electrical measurement technologies are well established. Both thermal and photon detectors convert incident optical energy into electrical signals; in the thermal detector, the initial output takes the form of heat before conversion. Either detector type may be a "point" or an "area" detector. The former are single-element detectors, designed to respond to incident energy. The latter are one- or two-dimensional arrays used particularly for imaging, and include mechanisms to read out the signal on the array. Table 5.1 gives examples of photon and thermal detectors, while Table 5.2 lists differences between them.
Online access to SPIE eBooks is limited to subscribing institutions.