Fabry-Pérot interferometer

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Fabry-Pérot interferometer

scientific instrument

Also known as: Fabry-Pérot etalon, variable-gap interferometer(Show More)

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June 26, 2026

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The Fabry-Pérot interferometer is a scientific instrument developed by Charles Fabry and Alfred Pérot in 1897. It is a type of optical interferometer that uses two highly reflective, parallel plates, known as an etalon.

This design causes light waves to undergo multiple reflections, with their intensity diminishing very slowly. This results in the formation of very narrow and sharp interference fringes. These fringes are valuable for revealing fine structures within line spectra, determining the widths of spectral lines, and precisely measuring wavelengths. The instrument's ability to resolve fine spectral details makes it a crucial tool in spectroscopy.12

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optical interferometer
The Fabry-Pérot interferometer (variable-gap interferometer) was produced in 1897 by the French physicists Charles Fabry and Alfred Pérot. It consists of two highly reflective and strictly parallel plates called an etalon. Because of the high reflectivity of the plates of the etalon, the successive multiple reflections…
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The Fabry-Pérot interferometer (variable-gap interferometer) was produced in 1897 by the French physicists Charles Fabry and Alfred Pérot. It consists of two highly reflective and strictly parallel plates called an etalon. Because of the high reflectivity of the plates of the etalon, the successive multiple reflections…
Read More

spectroscopy
Interference
The Fabry-Pérot interferometer consists of two reflecting mirrors that can be either curved or flat. Only certain wavelengths of light will resonate in the cavity: the light is in resonance with the interferometer if m(λ/2) = L, where L is the distance between the two mirrors,…
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The Fabry-Pérot interferometer consists of two reflecting mirrors that can be either curved or flat. Only certain wavelengths of light will resonate in the cavity: the light is in resonance with the interferometer if m(λ/2) = L, where L is the distance between the two mirrors,…
Read More

nebula
20th- and 21st-century discoveries
…higher spectral resolution astronomers employ Fabry-Pérot interferometers. Spectra provide powerful diagnostics of the physical conditions within nebulae. Images and spectra provided by Earth-orbiting satellites, especially the Hubble Space Telescope, have yielded data of unprecedented quality.
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…higher spectral resolution astronomers employ Fabry-Pérot interferometers. Spectra provide powerful diagnostics of the physical conditions within nebulae. Images and spectra provided by Earth-orbiting satellites, especially the Hubble Space Telescope, have yielded data of unprecedented quality.
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Charles Fabry
…primary research instrument was the Fabry–Pérot interferometer, invented in 1896 in collaboration with Alfred Pérot. This instrument was widely used for the measurement of the wavelengths of light and related studies. While applying it to study the light spectra of the Sun and stars, Fabry demonstrated that solar ultraviolet radiation…
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…primary research instrument was the Fabry–Pérot interferometer, invented in 1896 in collaboration with Alfred Pérot. This instrument was widely used for the measurement of the wavelengths of light and related studies. While applying it to study the light spectra of the Sun and stars, Fabry demonstrated that solar ultraviolet radiation…
Read More