Optics: measuring and testing – By configuration comparison – With comparison to master – desired shape – or reference voltage
Reexamination Certificate
2005-04-26
2005-04-26
Toatley, Jr., Gregory J. (Department: 2877)
Optics: measuring and testing
By configuration comparison
With comparison to master, desired shape, or reference voltage
C356S458000, C356S369000, C356S237100
Reexamination Certificate
active
06885449
ABSTRACT:
An optical inspection system (10) for comparing surface structures of test and reference objects comprises a laser (12), a photorefractive crystal (24) and a detector (30). A refractive index grating corresponding to a diffraction pattern of a surface structure of the reference object is present within the photorefractive crystal (24) and acts as a spatial filter for light diffracted by surface structures of the test objects. If a surface structure of a test object matches that of the reference object, little or no light reaches the detector (30). If the surface structure of a text object differs from that of the reference object, light of greater power reaches the detector (30). The system (10) provides a simple pass/fail comparison test and light incident on the detector (30) requires no interpretation or other processing. The system (10) may be adapted to allow simple imaging of an edge of an object.
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Nixon & Vanderhye P.C.
Punnoose Roy M.
Qinetiq Limited
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