Field Compensated Static Interferometer for Fourier Transform Spectroscopy

A static interferometer comprising an entrance pupil, a splitter plate, a first mirror and a second mirror which are arranged in such a way that light beams originating from a collimated source are divided on the splitter plate, reflect on each of the mirrors and recombine while interfering at the output of the interferometer, further comprising at least one prismatic plate of index n, comprising a variable thickness ej, a first beam passing through the prismatic plate before reflecting on a reflecting surface of the first mirror, the reflecting surface comprising a plurality of zones, each zone j being situated at a mean distance Δj from a reference plane, the mean distance Δj varying from one zone to another, the reference plane being perpendicular to an optical axis and corresponding to a position of a plane mirror for which the optical path difference between the two interfering reflected beams is zero, the first mirror M1 and the prismatic plate being positioned in such a way that for a given zone j each thickness ej is substantially equal to Δj·n/(n−1).