A common application of these devices is observing the Zeeman effect in mercury or selecting a single spectral line from the sun, as these devices can be used to separate two rays with similar wavelength.
Banks of these devices made of diamonds are commonly found in add-drop multiplexers, and an extremely asymmetric form of these devices is named for Gilles and Tournais. The ratio of c to 2 n l cosine theta gives the free spectral range of one of these devices, and the full width at half maximum for one of these devices can be approximated by taking four over the square root of the coefficient of finesse. The center of these devices contain either two slightly wedge-shaped (*) plates whose separation can be varied, or a single plate with two reflective surfaces called an etalon, which is flanked by collimating and focusing lenses, creating multiple reflections. A common application of these devices is observing the Zeeman effect in mercury or selecting a single spectral line from the sun, as these devices can be used to separate two rays with similar wavelength. For 10 points, name this type of interferometer named for two French physicists.
Banks of these devices made of diamonds are commonly found in add-drop multiplexers, and an extremely asymmetric form of these devices is named for Gilles and Tournais.
Fabry-Perot interferometer [prompt on “interferometer”; accept etalon before mention]