It is possible to construct a surprisingly inexpensive and simple thermal radiometer from office supplies. Although the detector was designed to evaluate thermal energy hazards to an individual located in a harsh environment, undoubtedly other applications will surface. The radiometer features a nearly flat wavelength response and a wide field-of-view, is very insensitive to both acoustic energy and radio-frequency energy, is not prone to damage, and distinguishes between radiated thermal energy and thermal energy transferred by direct contact with hot materials. It is particularly noteworthy that the detector has functioned as a direct hazard monitor for optical radiation emitted by certain flash sources.
Terry L. Lyon, "Thermal radiometer constructed from ordinary office supplies," Optics News 12(3), 15-19 (1986)