Photometer

Published January 1995

In the broadest sense, a photometer is any instrument used to measure illuminance or irradiance. As applied in industrial photometry, a "photometer" is the general term covering instruments for detecting scattered light intensity , absorption, and fluorescence. Most photometers are based on a photoresistor or photodiode. Either exhibits a change in electrical properties when exposed to light, which can be detected with a suitable electronic circuit. (© Wikipedia, 2007)