SURFACE CURVATURE CHANGE COMPENSATING APPARATUS

摘要

PURPOSE: A surface curvature change compensating apparatus is provided to detect defects all over the glass surface by forming, in a vertical direction, a normal line at the inner surface of a CRT, while maintaining visibility of image uniform. CONSTITUTION: A surface curvature change compensating apparatus comprises an illuminating light source(D) for generating light to be radiated onto the surface of a test object; a camera(E) for photographing the image created by the light radiated from the illuminating light source and reflected at a predetermined point of the test object; and a cam(G) serving as a height adjusting unit for keeping a focal length of the camera constant, by maintaining, in a vertical direction, the normal line for surface curvature of the point of the test object, through the adjustment of the height of the surface of the test object.