Patent ID: 6490541
Filing Date: 2002-12-03
Classification: B23Q,G01B

Abstract:
An apparatus for visual measurement, comprising:an image pick-up system for picking up an image of an object to be measured to obtain image information, said image pick-up system including an optical system and an image pick-up means; a driving means for shifting a focal position of said image pick-up system and scanning along the optical axis relatively to said object, said focal position being located at said object side; a measurement means for measuring a relative displacement of said focal position of said image pick-up system along said optical axis; and an arithmetic means for computing a contrast value at each of a plurality of different regions of said image information obtained at each relative focal position by said image pick-up system during said driving means relatively shifting said focal position of said image pick-up system along said optical axis, and determining a measure for said each region based on said relative displacement along said optical axis obtained from said measurement means when said image contrast value comes to the maximum in said each region, wherein said arithmetic means computes the contrast values of the plurality of different regions of said image information with one scanning along said optical axis.