Heterodyne double interferometer with signal detector - passes reference and measuring beams over common paths and compensates for systematic errors

摘要

A heterodyne double interferometer uses intensity division of the coherent radiation from a coherent source. Both beams are passed via the same reference and measurement paths and their measurement signals detected separately and processed so systematic, periodic errors are compensated. In addition or alternately, the measurement signals can be detected with opposite signs to achieve a doubling of the resolution of the phase angle between two interference events. ADVANTAGE - Enables expansion of phase measurement to be achieved with improved interpolation by compensation of periodic systematic errors which can occur in polarisation optical version.