Pyrometry
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Pyrometry is the non-contact measurement of the temperature of an object, by measuring its self-emission and emissivity. An apparatus that measures the temperature by means of pyrometry is called a pyrometer or optical pyrometer.
Emissivity is a measure of the object's capability to emit electromagnetic radiation. The value of emissivity ranges from 0 to 1, where the emissivity of a perfect emitter also known as a black body is 1, and a theoretical object that does not emit radiation at all has an emissivity of 0.
The most advanced pyrometers measure both the emission of the object and its emissivity, while other pyrometers require the user to enter the emissivity value via the pyrometer's inputs (dials or digital communication).
Pyrometers are used in a variety of applications, from human body temperature monitoring (ear pyrometers) to industrial applications like metals manufacturing and semiconductor manufacturing.
Pyrometry of gases presents difficulties. These are most commonly overcome by using thin filament pyrometry or soot pyrometry. Both techniques involve small solids in contact with hot gases.
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