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Optical translation measurement

  • US 6,330,057 B1
  • Filed: 03/08/1999
  • Issued: 12/11/2001
  • Est. Priority Date: 03/09/1998
  • Status: Expired due to Term
First Claim
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1. A method for determining the relative motion of a surface with respect to a measurement device comprising:

  • illuminating the surface from a source with incident illumination, such that illumination is diffusely reflected from portions of the surface towards a detector;

    spatially filtering the diffusely reflected illumination such that the phase of the detected optical illumination from a given scatterer on the surface is substantially constant or linearly related to the translation of the surface;

    generating a signal by the detector responsive to the illumination incident on the detector; and

    determining the relative motion of the surface in a direction parallel to the surface from the signal;

    wherein illuminating the surface comprises illuminating the surface through a partially reflecting object placed adjacent to the surface which object reflects or diffracts illumination to the detector.

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