Apparatus for maintaining adjustment of coincidence and relative phase relationship of light beams in an interferometer

摘要

An apparatus for maintaining the adjustment of coincidence and relative phase relationship of light beams in an optical interferometer comprises the passing of a measuring light beam and of a control beam through substantially the same paths of the interferometer. Any change in optical alignment of interferometer components from a set condition is manifest as a change of the electrical signal produced by photoelectric sensing means which receive the control beam. The change of the electrical signal is processed by an electrical circuit and fed to one or more positioning means supporting an optical component of the interferometer for causing a repositioning of such component to thereby restore the set condition. In a typical embodiment, the component is a reflective surface mounted on a set of piezoelectric positioning means.