Fabry-Perot interferometer misalignment: the effect on image plane tilt

Abstract

Many papers have been published on the imaging effects in Fabry-Perot interferometers. Hodgkinson and Vukusic1 have published the effects of secondary fringes that exist when the interference fringes are not focused. McMillan2 described the effects of fringe shift and of multiple source fringe splitting that is caused by misalignment. While observing Fabry-Perot fringes through a microscope, we found that the effects of plate misalignment could be corrected by tilting the microscope image plane to match the interferometer image tilt. Slight misalignment causes large image plane tilts that are related to the interferometer plate separation and the interferometer finesse. In our application, the interferometer was inaccessible in a vacuum chamber. By tilting our observation plane at the interferometer image plane outside the chamber, acceptable data could be obtained without taking the chamber apart to realign the interferometer.