Shapiro and Shapiro
Apparatus for detecting foreign particles on a surface of a reticle or pellicle
 An apparatus for detecting foreign particles on a surface of a reticle or pellicle comprises an optical system through which a light beam forms a light spot on the surface. The surface and the light spot are shifted relatively so that the light spot scans the surface. Light detectors receive light scattered by a foreign particle and directed in different directions, respectively, and generated photoelectric outputs by which the presence of the foreign particle is discriminated. Beam diameter and scanning speed are varied to provide the most effective operation for particles of different sizes. 
Nikon Corporation
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G01N G01N G03F G03F
additional inventional inventional inventional
Fuminori Kinya Kazunori Sunao
Hayano Kato Imamura Murata