A spectrophotometer is a photometer that can measure intensity as a function of the light source wavelength. Important features of spectrophotometers are spectral bandwidth and linear range of absorption or reflectance measurement.
A spectrophotometer is commonly used for the measurement of transmittance or reflectance of solutions, transparent or opaque solids such as polished glass, or gases. However they can also be designed to measure the diffusivity on any of the listed light ranges that usually cover around 200 nm - 2500 nm using different controls and calibrations.
- "Spectrophotometry". The National Institute of Standards and Technology. 02 August 2013. http://www.nist.gov/pml/div685/grp03/spectrophotometry.cfm. Retrieved 05 August 2014.