Patent ID: 8497993

Claim:
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, the static interferometer further comprising: at least one prism of index n, having a face whose slope forms a predetermined angle α n with respect to a plane perpendicular to an optical axis, thus having a variable thickness e j , a first beam passing through the at least one prism before reflecting on a reflecting surface of the first mirror, the first mirror being a staircase with the reflecting surface comprising a plurality of zones, each zone j being situated at a mean distance Δ j from a reference plane, the mean distance Δ j varying from one zone to another, tilted in such a way that the first beam incident on the first mirror is reflected in a same direction as the first incident beam, 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 and the at least one prism being positioned in such a way that for a given zone j each thickness e j is substantially equal to Δ j n/(n−1), wherein the angle of tilt α n of the prism is substantially equal to α n = Arc ⁢ ⁢ tan ⁡ ( n 2 · ( n 2 - 1 ) · OPD T L P ) , where n is the index of the plate, OPD T the variation in total optical path difference created by the device and L P the width of the pupil of the interferometer.