Dual high stability interferometer

摘要

A dual high stability interferometer system capable of measuring linear and angular displacement simultaneously of a movable plane mirror (90) comprises a frequency stabilized laser input beam (10) which is divided into two parallel spatially displaced beams by a beamsplitter (14). An optical system (20) is disposed to produce a first output beam having two orthogonally polarized components in which the phase difference between the two components of the third output beam is related to four times the linear displacement of the movable plane mirror (90) at a first position. A polarizer (93) mixes the orthogonal components of the third output beam with the interference between the two polarization components being detected by a photodetector (94) which produces an electrical signal (96) from which a phase meter/accumulator (99) extracts the phase change, with this phase change being related to four times the linear displacement of the movable mirror (90) at the first position. The optical system (20) also produce a second output beam whose orthogonally polarized components have a phase difference related to four times the linear displacement of the movable mirror (90) at a second position. Another polarizer (95) mixes these orthogonal components and a photoelectric detector (194) and another phase meter/accumulator (109) cooperate to provide a second measured phase which is related to four times the linear displacement of the movable mirror (90) at the second position.