Monochromator
![Monochromator in an x-ray beamline at the Advanced Photon Source, Argonne National Laboratory.](/Images/godic/202501/28/APS_-_Kohzu_monochromator5900.jpg")
![Diagram of a Czerny–Turner monochromator.](/Images/godic/202501/28/Czerny-Turner_Monochromator.svg5900.png")
![A combined reflecting-focusing diffraction grating](/Images/godic/202501/28/Parabolic_Reflective_Diffraction_Grating5900.jpg")
![A Fastie–Ebert monochromator. This is similar to the Czerny–Turner but uses a common collimator/refocusing mirror.](/Images/godic/202501/28/Monochromator5900.jpg")
A monochromator is an optical device that transmits a mechanically selectable narrow band of wavelengths of light or other radiation chosen from a wider range of wavelengths available at the input. The name is from the Greek roots mono-, "single", and chroma, "colour", and the Latin suffix -ator, denoting an agent.