Patent ID: 6488398
Filing Date: 2002-12-03
Classification: G02B

Abstract:
In optical gaging apparatus for examining a workpiece positioned beneath the aperture of a variable magnification optical system, an improved substage illuminator, comprisinga housing positioned beneath the workpiece that is to be examined, and having therein an opening registering with the aperture in said optical system, a light source connected to said housing and operable to direct a circular beam of light through said opening in said housing toward said aperture and the underside of said workpiece, a collimating lens in said housing between said light source and said opening to collimate said light beam, an anti-glare filter mounted in said housing over said opening at the side of said collimating lens remote from light source, and means for selectively adjusting the diameter of said beam of light directed through said opening, thereby to cause said beam exactly to match and to fill the aperture of said optical system for any adjustment of the F/number of said optical system.