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Position detecting method having reflectively scattered light prevented from impinging on a detector

  • US 5,229,617 A
  • Filed: 11/06/1992
  • Issued: 07/20/1993
  • Est. Priority Date: 07/28/1989
  • Status: Expired due to Term
First Claim
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1. A method of detecting the position of a substrate by using a grating pattern formed on the substrate, characterized in that a radiation beam is projected to the grating pattern by which a diffraction beam is produced and received by a sensor, wherein any reflectively scattered light from an edge of an outer peripheral part of the diffraction pattern is substantially prevented from being received by the sensor;

  • and that an output signal from the sensor responsive substantially only to the diffraction beam from the grating pattern is used to determine the position of the substrate.

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