Like thermal cameras, pyrometers or infrared thermometers are sensors that measure temperature by analysing the infrared radiation emitted by an object's surface. However, pyrometers measure the temperature of an object through a single point instead of an entire area.

A pyrometer is a type of thermal sensor used for measuring high temperatures of a surface, often in large furnaces or kilns. These devices measure the temperature of an object or surface from the thermal radiation emitted, also known as radiometry.

Thus a pyrometer is a type of infrared thermometer. The designation radiation thermometer has evolved over the past decade as an alternative to optical pyrometer. Therefore the terms infrared pyrometer and radiation thermometer are used interchangeably by many references.

These temperature radiations are recorded by a pyrometer, a “radiation thermometer” resulting in point like information. In contrast, when the information obtained is optically recorded as an entire scene ie. buildings, operational equipment etc. and displayed as a “temperature picture” this is known as thermography.