Radiant energy – Photocells; circuits and apparatus – With circuit for evaluating a web – strand – strip – or sheet
Patent
1997-06-09
1998-08-25
Le, Que
Radiant energy
Photocells; circuits and apparatus
With circuit for evaluating a web, strand, strip, or sheet
25055945, 356376, G01N 2186
Patent
active
057985324
ABSTRACT:
An apparatus for measuring warp of a semiconductor wafer cassette is provided. A wafer cassette is secured within a housing that places the end wall of the cassette in a predetermined position. An array of laser diodes is arranged to transmit a light reference across the end wall of the cassette. An array of photo detectors is placed opposite the laser diodes to detect the transmitted light reference. If the end wall of the cassette is not warped, the transmitted light is blocked by the cassette. If the end wall of the cassette is warped, some or all of the photo detectors receive the transmitted light. Measurement of the light received by the photo detectors is used to determine the nature and degree of warp on the end wall of the cassette.
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Huffman James W.
Integrated Device Technology Inc.
Le Que
LandOfFree
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