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 powe 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?