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Method and apparatus for detecting and sizing particles on surfaces

  • US 4,967,095 A
  • Filed: 09/25/1989
  • Issued: 10/30/1990
  • Est. Priority Date: 06/28/1989
  • Status: Expired due to Term
First Claim
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1. A particle detection apparatus comprising,means for supporting an object, a surface of which can be tested,means for providing a local zone of vapor supersaturation over a portion of said surface, whereby droplets of liquid can condense around any particles on said object in said portion of said surface,means for directing a light beam adjacent to said local zone of vapor supersaturation toward said surface,means for providing relative movement of said object with respect to said local zone of vapor supersaturation and said adjacent light beam so as to cause relative movement of said portion of said surface having said droplets into a path of said beam, whereby light from said beam is scattered by said droplets, andmeans positioned in scattered light receiving relation to said surface for detecting light scattered by said droplets, whereby particles on said object around which said droplets have condensed are detected.

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