Shape measuring apparatus

摘要

A shape measuring apparatus is provided, which is capable of accurately measuring the shape of an observed surface of an object to be measured and which can be designed to be compact in size and light in weight. An optical reflected image from an observed surface of an object to be measured and an optical reflected image from a reference surface are interfered with each other to generate interference light. The interference light is dispersed into at least three beams, which are shifted in phase by respective predetermined phase shifting amounts. At least three interference fringe images are simultaneously captured by at least one image pickup device which is smaller in number than the interference fringe images. At least three pieces of interference fringe image information are calculated using the at least three obtained interference fringe images and the predetermined phase shift amounts to thereby calculate a shape of the observed surface from the at least three pieces of interference fringe image information.