ABSTRACT
This chapter examines the theory underlying the operation of no-touch, radiation thermometers that use a pyroelectric sensor to measure surface temperature by using the surface's blackbody (BB) radiation. The long-wave, infrared (LIR) thermometer is a device that comes very close to being an ideal, NI diagnostic medical instrument. Its operating principle is based on the same technology used by IR intruder alarms and light switches. That is, when a sensitive, pyroelectric material (PYM) is exposed to a surface having a temperature different from its ambient temperature, a minute electric current is generated by the PYM as it absorbs or looses heat to this surface by radiation. The chapter describes the physics of radiation heat transfer, the behavior of PYMs, the electronic circuits required to condition their output signals, and the basic design of the Braun ThermoScan ear thermometers.
