spectrograph

A spectrograph is an instrument used to disperse radiation, such as electromagnetic waves or sound, into its constituent wavelengths or frequencies, and then record or map this distribution, known as a spectrum. This process is fundamental to spectroscopy, a field that uses these spectral patterns to analyze the composition and structure of matter.123

Spectrographs and related instruments, like spectrometers, can analyze various types of radiation, including visible light, ultraviolet, infrared, and X-rays. They work by either exciting a sample to emit radiation and then analyzing that emission, or by passing radiation through a sample and analyzing which wavelengths are absorbed. The resulting spectrum provides detailed information about the atoms and molecules within the sample, making spectroscopy a powerful tool in fields ranging from chemistry to astronomy. For instance, analyzing the light from distant galaxies has revealed that the universe is expanding.2453