3) A Fabry-Perot interferometer with fixed plate spacing t = 1.50mm is used to examine filtered light from a helium lamp, with wavelength lambda = 587.56nm. The plates have reflectance R = 0.950.
a) What is the free spectral range (in nm) for this spacing t and wavelength lambda?
b) What is the smallest resolvable wavelength difference for this setup?© BrainMass Inc. brainmass.com October 24, 2018, 7:50 pm ad1c9bdddf
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This solution provides explanation of how to find the free spectral range, and what the smallest resolvable wavelength is.
A Fabry-Perot interferometer is to be used to resolve the mode structure of a He-Ne laser operating at 632.8 nm. The frequency separation between the modes is 150 MHz. The plates are separated by an air gap and have a reflectance (r^2) of 0.999.
(a) What is the coefficient of finesse of the instrument?
(b) What is the resolving power required?
(c) What plate spacing is required?
(d) What is the free spectral range of the instrument under these conditions?
(e) What is the minimum resolvable wavelength interval under these conditions?