Impact of mechanical disturbances to the placement of reference light in Fourier transform interferometers

Fourier transform interferometers usually need a dedicated reference light to precisely track optical path difference changes. There are a few different ways to incorporate the reference light into the optical system. This paper conducted experiments to give a test of how different ways of incorporating reference light are affected by mechanical disturbances. It found that placing the reference light in different path than the test light can be very sensitive to mechanical disturbance errors while propagating the reference light together with the test light can be very robust against mechanical vibrations of optical components.