Optical spectrometer

An instrument that separates optical radiation by wavelength and measures its intensity across a spectrum. Its design may use dispersive optics, an interferometer, or wavelength-selective filters.

Diffraction grating: An optical component with periodic structure that diffracts light into wavelength-dependent directions. Gratings separate wavelengths by sending them along distinct angles.
Electromagnetic spectrum: The full range of electromagnetic radiation, ordered by frequency or wavelength. Optical instruments measure a limited region of this broader spectrum.
Astronomical spectroscopy: The analysis of celestial radiation by its wavelength-dependent features. Spectrometers reveal the composition, motion, and physical conditions of astronomical sources.
Spectroscope: An optical instrument that displays or visually separates a spectrum without necessarily measuring it quantitatively. A spectrometer quantifies spectral signals, whereas a spectroscope may only show them.
Prism: A transparent optical element that refracts light, with different wavelengths bent by different amounts. Prisms provide a refractive alternative for separating wavelengths.
Wavelength: The spatial period of a wave, measured between corresponding points on successive cycles. Wavelength is the coordinate along which an optical spectrometer separates radiation.
Raman spectroscopy: A technique that identifies molecular vibrations through wavelength shifts in scattered light. It uses optical spectral measurements to infer molecular structure.
Monochromator: An optical device that selects a narrow wavelength band from broader radiation. A monochromator isolates wavelengths; a spectrometer measures their distribution.
Interferometer: An instrument that uses interference between light paths to measure optical properties. Fourier-transform spectrometers encode wavelengths in an interference signal before computation.
Spectrum: A distribution of a physical quantity across a range of wavelengths, frequencies, or energies. The instrument produces a wavelength-resolved spectrum from incoming radiation.

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Atomic emission spectroscopyRelated: It resolves emitted wavelengths into measurable spectral lines.