Spectrometer, tool that analyzes an object through a spectrum of light. This device can be used to examine evidence at crime scenes, to determine the composition of celestial bodies, and to detect pollution in the sky or water. Spectroscopes allow a scientist to view the light spectrum of an object, which for every object is different. Sometimes photographs of the light spectrum are taken by a spectrograph. The brightness of light in an object may be determined through a spectrophotometer.