Pyrometer

A Pyrometer is an instrument for the measurement of temperature, generally the term is applied to instruments measuring temperatures above 600 degrees Celsius.

One of the most common pyrometers is the absorption-emission pyrometer which is a thermometer for determining gas temperature from measurement of the radiation emitted by a calibrated reference source before and after this radiation has passed through and been partially absorbed by the gas. Both measurements are made over the same wavelength interval.