Patent ID: 7233400
Filing Date: 2007-06-19
Classification: G01B

Abstract:
1. An interferometer for measuring virtual contact surfaces, comprising: an interference optical system that irradiates an object and a reference surface of the interferometer with measuring light, wherein the object comprises: a first small surface to be detected formed so as to be positioned in a first arrangement pattern on a first reference virtual surface; and a second small surface to be detected formed so as to be positioned in a second arrangement pattern on a second reference virtual surface substantially parallel to the first reference virtual surface, so as to obtain interference light by synthesizing a reflected light from the first or second small surface to be detected and a reflected light from the reference surface with each other; and a light detecting surface on which an intensity distribution of the interference light is detected, wherein the measuring light is low coherent light having a coherent distance shorter than an optical path length difference between the reflected light from the first small surface to be detected and the reflected light from the second small surface to be detected, wherein the interferometer comprises: an optical path length regulating section that regulates, during first measuring time in which the first small surface to be detected is an object of measurement, optical path length so that the reflected light from the first small surface to be detected and the reflected light from the second small surface to be detected interfere with each other, and regulates, during second measuring time in which the second small surface to be detected is an object of measurement, optical path length so that the reflected light from the second small surface to be detected and the reflected light from the reference surface interfere with each other; an image forming regulating section that forms during the first measuring time at least a part of an image of the first small surface to be detected, and forms during the second measuring time at least a part of an image of the second small surface to be detected, in each of a plurality of detecting unit regions set in a divided manner on the light detecting surface; and an interference fringe obtaining section that acquires during the first measuring time first interference fringe information corresponding to a shape of a first virtual contact surface engaged with the first small surface to be detected, and acquires during the second measuring time second interference fringe information corresponding to a shape of a second virtual contact surface engaged with the second small surface to be detected, based on each optical intensity averaged and detected in each of the detection unit regions.