Patent Document ID: 5500737
Application ID: 08094680
Patent Status: 1

Claim One:
1. A method for measuring the contour of a surface, comprising the steps of: (a) projecting a line of light on the surface to illuminate a selected contour feature of the surface: (b) generating an image of the selected contour feature illuminated by the line of light by imaging an off-axis projection of light reflected from the illuminated contour feature; and (c) evaluating the selected contour feature by comparing the image against a predetermined specification; wherein any distortion and keystone effect in the image caused by off-axis imaging of the illuminated contour feature is corrected by the steps of; positioning a square grid within the field of view of an image generating means to provide an off-axis image of the square grid; superimposing an electronically produced grid corresponding to the square grid over the off-axis image of the square grid; adjusting the vertical and horizontal grid lines of the electronically produced grid to match the convergence of the vertical and horizontal grid lines of the off-axis square grid image; storing a vertical and a horizontal convergence adjustment parameter corresponding to a displacement of the electronically produced grid lines to match the grid lines of the off-axis image; adjusting the vertical and horizontal grid lines of the electronically produced grid to match the spacing between the vertical and horizontal grid lines of the off-axis square grid image; and storing a vertical and horizontal spacing adjustment parameter corresponding to a displacement of the electronically produced grid lines to match the grid lines of the off-axis image, the convergence adjustment parameters and the spacing adjustment parameters being used to correct the off-axis image of the illuminated contour feature.