Patent ID: 6373978
Filing Date: 2002-04-16
Classification: G01B

Abstract:
A three-dimensional shape measuring apparatus using a confocal imaging system comprising:a confocal imaging system which comprises a scanning confocal optical system that scans an object with one or more confocal optical systems mechanically or optically or an arrayed confocal optical system consisting of a plurality of two-dimensionally arrayed confocal optical systems, and a two-dimensional photoelectric sensor for converting a two-dimensional image formed thereon by the confocal optical system into electricity; means for changing the relative distance in the Z direction between an object and the object-position-in-focus; and an image processor which calculates the three-dimensional shape of the object from confocal images acquired at different distances in the Z direction between the object and the object-position-in-focus by the confocal imaging system and the means for changing the distance in the Z direction between an object and the object-position-in-focus; characterized in that said image processor estimates the position from which the intensity of the reflected light for each pixel of the confocal images is maximum, at a higher accuracy than the sampling interval of confocal images, by interpolation using the intensity of light of the pixel at the positions where the confocal images are acquired, and the relationship between the intensity of light detected by a confocal imaging system and the distance from the object-position-in-focus to an object point; Optical intensity=(|sin kz(1âˆ’cos &thgr;) |/|kz(1âˆ’cos &thgr;)|)2, wherein k is the wave number of illuminating light, sin &thgr; is the numerical aperture in the objective lens of the confocal imaging system, and z is a distance from the object-position-in-focus to an object point.