Patent ID: 6501546
Filing Date: 2002-12-31
Classification: G01N

Abstract:
A method for the inspection of an edge of a sheet of glass, comprising the steps of:a) supporting and moving a sheet of glass in a plane in a first direction, said sheet of glass being maintained in a generally constant plane; b) directing a laser beam along an optical path onto said edge of the sheet of glass at an angle to said first direction and directing light reflected from the edge along said optical path to an optical recording device thereby to image said edge, the light reflected from the edge of the sheet of glass being coaxial with the laser beam directed onto the edge of the sheet of glass; and c) adjusting the optical path to control the total path length of said laser beam from said laser to said edge and the reflected light from said edge to said optical recording device at a substantially constant length thereby to reduce light intensity variations at said optical recording device resulting from variations in the lateral spacing between said edge and said optical path.