Particle Measuring Systems, Inc.

Vaughn C Hoxie

Robert G Knollenberg

Clinton E Utter

System and method are disclosed for inspecting objects, such as sheets of flat panel glass, to detect flaws or contamination at a surface. The surface to be inspected is illuminated with 253.7 nm ultraviolet (UV) radiation to assure detection of defects only at the front surface subjected to the radiation. UV radiation reaching the front surface is scattered by defects at the front surface, and scattered UV radiation is collected by a UV dark field imaging system and directed by the imaging system to a detecting unit, preferably including a charge coupled device (CCD). The detecting unit senses UV radiation scattered at the surface due to defects within a selected size range and provides an output to a processing unit providing an output indicative of the defects sensed within the selected size range. The illumination system preferably illuminates the entire surface to be inspected, an enclosed dark field chamber having shielding houses the illuminating source and radiation collecting system, an anti-reflecting UV coating is preferably used, as is a bandpass filter, and the detecting unit is preferably cooled, accompanied by heating of the imaging system. The system is capable of detecting defects at least as small as five microns using a ten second sampling period.

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Longmont, CO, United States of America

Vaughn C Hoxie