Patent ID: 7027144
Filing Date: 2006-04-11
Classification: B01F,B05B,B05C,G01M,G01N

Abstract:
1. A lens inspection method of inspecting a lens to determine whether said lens is defective or not, said lens inspection method comprising a first inspection process comprising the steps of: projecting an inspection light simultaneously onto an entire area of said lens from one axial side of said lens such that a dark field image of said lens is photographed by a photoelectric imaging device that is placed on the other side of said lens, to detect those rays of the inspection light that are scattered at lens surfaces; and judging that said lens has at least a scratch thereon when photoelectric signals obtained from said photoelectric imaging device have intensities of more than a predetermined level at least across an area of said dark field image, and said area is larger than a predetermined threshold value, and a second inspection process comprising the steps of: projecting an inspection light simultaneously onto the entire area of said lens from said other side of said lens such that a dark field image of said lens is photographed by a second photoelectric imaging device that is placed on said other side of said lens, to detect those rays of the inspection light that are reflected from a surface of said other side of said lens; calculating an average intensity of photoelectric signals obtained from each of a plurality of unit sections defined in an inspection range of said photoelectric imaging device, said inspection range corresponding to said dark field image; and judging that said lens has an extraneous object thereon when a difference in said average intensity between adjacent two of said unit sections is above a predetermined threshold value.