Principles of radiation pyrometer

Temperature measurement is based on the measurement of radiation either directly by a sensor or by comparing with the radiation of a body of known temperature. The radiation pyrometer is a non contact type of temperature measurement.

The wavelength region having high intensity is between 0.1 to about 10. In this region,  is the ultraviolet region, 0.4 to 0.7 is the visible region and 0.7 onwards is the infrared region. With the increase in temperature, radiation intensity is stronger toward shorter wavelengths. The temperature measurement by radiation pyrometer is limited within 0.5 to  wave length region.

Total radiation pyrometer

A radiation pyrometer consists of optical component to collect the radiation energy emitted by the object, a radiation detector that converts radiant energy into an electrical signal, and an indicator to read the measurements.

The optical pyrometer is designed to respond narrow band of wavelengths that fall within the visible range of the electro-magnetic spectrum.

Thermal detectors are used as sensors. Their hot junction is the radiation sensing surface. Thermopiles can detect radiation of all wavelengths.