LASER BEAM PATH LENGTH DIFFERENCE DETECTOR, LASER PHASE CONTROLLER AND COHERENT OPTICAL COUPLER

摘要

A small-sized, low-cost and easy-to-use laser beam path length difference detector, a laser beam path length difference detector and a coherent optical coupler are provided. The laser beam path length difference detector detects an optical path length difference between propagating paths of a first laser beam (1) and a second laser beam (2), which are mutually coherent when the beams propagate in the two discretionary optical paths of a plurality of laser beam optical paths. The detector is provided with an optical path length changing means (4), which changes the difference between the optical path length of the first laser beam (1) and that of the second laser beam(2), a wavefront inclination generating means (5), which inclines at least one of the wavefronts of the first laser beam (1) and the second laser beam (2), and a two-dimensional detector (6), which detects the interfering light intensity distribution of the first laser beam (1) and the second laser beam (2) after they pass through the wavefront inclination generating means.