Patent ID: 6020963
Filing Date: 2000-02-01
Classification: G01B,G01N

Abstract:
An optical quadrature interferometer comprising:a light source providing a beam of light;a first beamsplitter oriented at an angle with respect to said light source, said first beamsplitter receiving said beam of light and splitting said beam of light into a first secondary light beam and a second secondary light beam;a recombining beamsplitter;a first reflective element oriented such that said first reflective element receives said first secondary light beam and reflects said first secondary light beam along a different axis to said recombining beamsplitter;a second reflective element receiving said secondary light beam and oriented to direct said secondary light beam along a different axis;a quarter wave plate receiving said second secondary light beam from said second reflective element, said quarter wave plate providing a 90.degree. phase shift between vertically and horizontally polarized components of the beam resulting in a circularly polarized light beam;a target receiving said circularly polarized light beam, said target causing a change to said circularly polarized light beam resulting in a measurement light beam;said recombining beamsplitter combining said measurement light beam with said first secondary light beam to provide a first resultant light beam and a second resultant light beam, said first secondary light beam having approximately the same frequency as said beam of light;a first polarizing beamsplitter receiving said first resultant light beam and splitting said first resultant light beam into a first secondary resultant light beam and a second secondary resultant light beam;a second polarizing beamsplitter receiving said second resultant light beam and splitting said second resultant light beam into a third secondary resultant light beam and a fourth secondary resultant light beam; andat least one imaging system for displaying data from said first secondary resultant light beam, said second secondary resultant light beam, said third secondary resultant light beam, and said fourth secondary resultant light beam.