spectrometer

The term spectrometer is for a device that measures a spectrum, e.g., the intensity of light at different wavelengths, a practice called spectrometry. As such, a spectroscope or spectrograph can be termed a spectrometer. Those two terms originally distinguished between a device that you look through (spectroscope) and one that recorded the spectrum on film (spectrograph), but modern advanced instruments virtually always focus the spectrum on a CCD or similar sensor, allowing the spectral data to be transmitted, recorded and analyzed electronically, and any of the three terms may be used. The terms may be used for analyzers of any part of the electromagnetic spectrum, but when used for other than visible light, that is usually mentioned, e.g., the phrase "X-ray spectrometer". Spectrometers are used as lab instruments and telescope instruments.

The term mass spectrometer is used for a different kind of device that does not concern light or other EMR: one that measures the relative number of particles entering it according to each individual particle's mass. Space probes often include mass spectrometers to analyze material collected, such as dust. Information about the masses provide clues to its makeup.