ABSTRACT
Light detectors are used for the detection and power measurement of light. Thermal detectors make use of the heating effect of light. Photon detectors, are strongly dependent upon the wavelength of light. The operation of thermal detectors depends on the heating produced by light in an absorbing surface of the detector. The resultant increase in the temperature of the detector may be measured by the change of its resistance, as in a bolometer, or by the change of thermoelectric potential at a junction between two metals, as in a thermocouple. Photoconductive detectors are most widely used for the detection of infrared light. Photoconductive detectors were among the first solid-state optical detectors. Quantum well infrared photodetectors are another class of photoconductive detectors that operate in the mid Infrared. Avalanche photodiodes are photodiodes with an internal gain mechanism similar to a photomultiplier tube.
