Patent ID: 8314849

Claim:
A shape measuring device having a projecting system that projects a projection pattern to a surface to be measured; an image-forming optical system that forms an image of said projection pattern projected to said surface to be measured; an image pickup device that picks up the image of said projection pattern formed by the image-forming optical system; and a focusing detecting device that detects a focusing state of the image picked up by said image pickup device, and that measures a shape of said surface to be measured, the shape measuring device comprising: a computer operable to provide: a conjugated position changing device that changes a position conjugated with an image pickup surface of said image pickup device with respect to said surface to be measured along an optical axis direction of the image-forming optical system; a calculating device that detects a change of position of said projection pattern on the basis of a plurality of images obtained by said image pickup device when said conjugated position is changed with respect to said surface to be measured; and an evaluating device that evaluates a detection error of the focusing state detected by said focusing detecting device on the basis of the change of the position of the projection pattern detected by said calculating device.