A spectrometer is an instrument used to intensely measure light over a specific portion of the electromagnetic spectrum, to identify materials. The instrument produces lines, much like those produced from diffraction grating as covered in a previous atom, and then measures the wavelengths and intensities of those lines.
shows a diagram of how a spectrometer works. The source is placed in front of a mirror, which reflects the light emitted from that object onto a diffraction grating. This grating then disperses the emitted light to anther mirror which spreads the different resultant wavelengths and reflects them onto a detector which records the findings. This type of instrument is used in spectroscopy.
Source: Boundless. “The Spectrometer.” Boundless Physics. Boundless, 26 May. 2016. Retrieved 02 Oct. 2016 from https://www.boundless.com/physics/textbooks/boundless-physics-textbook/wave-optics-26/applications-of-wave-optics-177/the-spectrometer-647-6066/