Real space length measuring method and a calibration method of the optical system by the imaging means, and the reference gauge to be used for calibration of the optical system

摘要

PROBLEM TO BE SOLVED: To establish a method for precisely measuring the actual space length per picture element, with which it is possible to make measurement and adjustment of the photographing range, measure the distortion of the image, and make correction of the distorted image by means of feedback of the obtained results. ;SOLUTION: The mean number of lattices per picture element row in a photographing means is calculated for any arbitrary region in the inspection region of a lattice image (103), and the resultant is multiplied by the lattice pitch so that the actual space length of the region in a certain direction is calculated (104), and the obtained value is divided by the number of picture elements in that direction so as to give the actual space length per picture element of the lattice image (105). This enables calculation of the photographing means (106), adjustment of the photographing range, calculation of the distortion distribution of the image obtained (107), and correction of the image using these (109), so that it is practicable to precisely measure the object through calibration in the optical system in use.;COPYRIGHT: (C)1997,JPO