LASER PHASE DIFFERENCE DETECTOR AND LASER PHASE CONTROLLER

摘要

A laser phase difference detector comprising an optical path branch section for branching individual laser beams constituting laser beam groups into a first laser beam group traveling on a first optical path and a second laser beam group traveling on a second optical path, a beam selecting/extracting section for passing one laser beam in the first laser beam group selectively as a reference light, a section for varying the optical path length of the first optical path, an optical path synthesizing section for synthesizing the reference light and individual laser beams constituting the second laser beam group to produce an interference light, and a photodetector for detecting the intensity of an interference light, wherein an optical path length for maximizing the intensity of interference light is detected for individual laser beams constituting the second laser beam group by varying the first optical path length at the optical path length varying section and the phase difference between individual laser beams is determined based on the optical path length thus determined.