fabry-perot interferometer

<apparatus, physics> A type of interferometer with two parallel mirrors (with a variable separation of a few centimetres) arranged so that incoming light is reflected between them multiple times before ultimately being transmitted. ... Useful in spectroscopy because it gives very good frequency resolution without losing too much of the incide...
Found on http://www.encyclo.co.uk/local/20973

Fabry-Pérot interferometer

A type of optical interferometer that, when placed in front of the diffraction grating in a spectrograph, can reveal fine details in the spectrum of a galaxy, nebula, or other extended object that are beyond the scope of a grating alone. Light from an object is passed through an etalon – a pai...
Found on http://www.daviddarling.info/encyclopedia/F/Fabry-Perot_interferometer.html
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