Patent ID: 7652771

Claim:
An interferometer, comprising: a first reflective surface having a nominal orientation; a second reflective surface having a nominal orientation orthogonal to the nominal orientation of the first reflective surface; a retroreflector facing the first reflective surface; a double polarizing beam splitter (DPBS) between the first reflective surface and the retroreflector, the DPBS comprising a first beam-splitting surface and a second beam-splitting surface, the beam-splitting surfaces each having a nominal orientation with respect to the nominal orientation of the first reflective surface; and a quarter-wave plate between the double polarizing beam splitter and each of the first reflective surface and the second reflective surface; in which at least part of at least one of the first reflective surface, the second reflective surface, the first beam-splitting surface and the second beam-splitting surface is effectively tilted relative to the respective nominal orientation thereof and constitutes a respective tilted surface.