Patent ID: 6657219
Filing Date: 2003-12-02
Classification: G01B

Abstract:
An optical detection and measurement system for detecting the position of the plane of a reflective surface of a workpiece, comprising;a work table for holding said workpiece; a light source positioned to direct a collimated beam of light onto the said reflective surface of said workpiece to produce at least one reflected beam of light; a quadrant detector having four distinct photosensitive elements in quadrant relationship each producing a photocurrent output positioned to receive said reflected beam of light; a diverging lens having a non-diverging optical axis center positioned to align the said non-diverging optical axis center with the center of said quadrant detector so that when a reflective beam of light passes therethrough, each of said four distinct photosensitive elements produces the same photocurrent output; and a control system for moving said work table to translate said at least one reflected beam of light to the said non-diverging optical axis center of said diverging lens to cause said quadrant detector to create a null condition where each of the said four photosensitive elements produce the same value of photocurrent output to thereby detect the position of the plane of said reflective surface of said workpiece.