A spectrophotometer is used to measure the intensity of light, or amount of photons, absorbed by a sample object or the amount of photons reflected from a sample object. The instrument is made up of a spectrometer for producing light and a photometer for measuring light intensity.
A spectrophotometer passes a light beam through a sample object and measures the intensity of light that reaches the detector. A spectrophotometer can either be categorized as a IR spectrophotometer or UV-visible spectrophotometer, depending on the light source's wavelength range.
The basic principle of spectrophotometry is that every compound transmits or absorbs light over a specified wavelength. Spectrophotometry is a useful method of quantitative analysis in fields like biochemistry, physics and chemistry.