I want to understand the importance of beam quality to interferometer systems. This article says the following:
A very high (close to diffraction-limited) beam quality, associated with a high spatial coherence, is often required for interferometers, optical data recording, laser microscopy, and the like.
But how does beam shape (elliptical vs circular/Gaussian) affect interferometry?
I'm specifically asking how the beam shape (elliptical vs circular/Gaussian) affects interferometry; and, so, should I aim to make (using optical elements) the beam as circular/Gaussian as possible (assuming it starts out more elliptical, such as from a laser diode). The goal is to maximise the performance of the interferometer (within reason).