Define Instrument for measurement of absorbed radiation-Colorimeter?

The simplest types of, photometric instruments are designed for measurements in the visible region of spectrum. You will come across the term colorimeter often used to describe such instruments. In this, the specific wavelength of light is isolated with interchangeable filters. The wavelength selection remains simple but in some of the instruments the detector and output systems are benefited from the applications of electronics so as to give digital displays in concentration units.