Optical interferometer

Claim 1

An optical interferometer for producing two interference patterns 90° phase-shifted relative to each other, particular for use in length measurements, comprising a light source emitting a light bundle, a collimator for spreading said light bundle, a partially transmissive optical body arranged in the path of said light bundle, said partially transmissive optical body having a first beam splitting partially silvered face, inclinedly arranged relative to the incident light bundle, a second and a third beam splitting and partially silvered face, substantially in parallel with and equally spaced relative to said first beam-splitting partialy silvered face, said first beam splitting partially silvered face splitting up said light bundle into a first passed-on partial light bundle and into a first reflected partial light bundle, a measuring reflector located in the path of said first passed-on partial light bundle, said measuring reflector back-reflecting the incident first passed-on partial light bundle to said partially transmissive optical body parallel, however, in lateral displacement to said first passed-on partial light bundle, said measuring reflector being displaceable along the path of said first passed-on partial light bundle, a reference reflector located in the path of said first reflected partial light bundle, said reference reflector reflecting the incident first reflected partial light bundle back to said partially transmissive optical body in parallel, however, laterally displaced to said first reflected partial light bundle, said first passed-on partial light bundle and said first reflected partial light bundle, after reflection, being fused at said first beam splitting partially silvered face of said partially transmissive optical body and producing a first interference pattern, said first beam splitting partially silvered face splitting up the impinging fused partial light bundles into a second passed-on partial light bundle passed through said face, and into a second reflected partial light bundle reflected thereupon, the second, reflected partial light bundle being deviated at said second beam splitting partially silvered face, and fusing with the passed through second passed-on partial light bundle, being deviated at said third beam splitting partially silvered face, thereby producing a second interference pattern at said first beam-splitting partially silvered face, said first interference pattern and said second interference pattern being 90° phase-shifted relative to each other, and means for evaluation of said interference patterns, phase-shifted relative to each other.