The optical pyrometer is a type of thermometer that measures thermal radiation without any physical contact with the object, thus detecting the temperature to which it is aimed.

Operating between 700 ° C and 4000 ° C, this instrument can measure temperatures above incandescence, molten metals, ceramics and other industrial processes, stars and also temperature in vacuum chambers. Pyrometers are now effective methods (with errors close to 2% and decreasing as temperature increases) for even negative temperature measurements.

Overall, pyrometers are advantageous equipment and have an extremely fast response time compared to the usual microsecond thermometers.