Patent ID: 6496269
Filing Date: 2002-12-17
Classification: G01B

Abstract:
A shape measuring apparatus comprising:an interference optical system including a reference surface member having a reference surface, for causing an optical reflected image from an observed surface of an object to be measured and an optical reflected image from said reference surface to interfere with each other to generate interference light; dispersing means for dispersing the interference light generated by means of interference by said interference optical system into at least three beams; shifting means for shifting said at least three dispersed beams by respective predetermined phase shifting amounts; interference fringe image obtaining means for simultaneously obtaining at least three interference fringe images obtained by means of shifting by said shifting means; and calculating means for calculating at least three pieces of interference fringe image information using said at least three obtained interference fringe images and said predetermined phase shift amounts to thereby calculate a shape of said observed surface from the at least three pieces of interference fringe image information, wherein said interference fringe image obtaining means comprises at least one image pickup device which is smaller in number than said interference fringe images.