Patent ID: 7768699
Filing Date: 2010-08-03
Classification: G01J

Abstract:
1. A laser phase difference detecting device comprising: an optical path splitting unit for splitting a laser beam group including a plurality of individual laser beams into a first laser beam group which travels along a first optical path and a second laser beam group which travels along a second optical path; a beam selection/extraction unit for selecting, as reference light, one laser beam from said first laser beam group so as to allow the selected laser beam to pass therethrough; an optical path length changing unit for changing an optical path length of said first optical path; an optical path combining unit for combining said first optical path and said second optical path such that said reference light and said second laser beam group are combined, producing interference light; and a light detector for detecting an intensity of said interference light, wherein said laser phase difference detecting device changes the optical path length of said first optical path using said optical path length changing unit so as to detect an optical path length which maximizes the intensity of said interference light for each of the laser beams in said second laser beam group, and determines a phase difference among the individual laser beams on a basis of the detected optical path length, and wherein the intensity of said interference light is related to the amplitude of said reference light, the amplitude of said laser beam to be measured, and a measured phase difference between said reference light and said laser beam to be measured.