Thermal detectors feel the heat of light

Photodetectors based on photoemissive, photoconductive, or photovoltaic effects belong to a general class of detectors known as quantum detectors because they involve direct quantum interactions between light and matter. But another important class of photodetectors functions through a more indirect process. Thermal detectors sense light by responding to the temperature increase that results when matter absorbs light energy. In principle, the phenomenon is no different than the sensation of warm