مقياس الإشعاع

Also known as roentgenometer

thumb|210px|An example of a Crookes radiometer. The vanes rotate when exposed to light, with faster rotation for more intense light, providing a quantitative measurement of electromagnetic radiation intensity. A radiometer is an instrument for measuring radiometric quantities such as radiant flux (power), irradiance, or radiance. Definitions typically limit radiometry to optical radiation, but some definitions include other kinds of electromagnetic radiation. Radiometers typically measure infrared radiation, visible radiation (light), ultraviolet radiation, or some combination of these.