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Rotating disc optical synchronization system using binary diffractive optical elements

  • US 5,258,862 A
  • Filed: 12/10/1992
  • Issued: 11/02/1993
  • Est. Priority Date: 12/10/1992
  • Status: Expired due to Fees
First Claim
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1. An optical synchronization system for a rotating disc comprising:

  • a light source for emitting a coherent light beam,means to collimate said coherent light beam,a first stationary binary diffractive optical element to alternately block and diffract said collimated light beam,a plurality of alternating second binary diffractive optical elements and blocking elements disposed circumferentially on said rotating disc such that said diffracted light beam from said first stationary binary diffractive optical element is alternately blocked by said alternating blocking elements and diffracted by said alternating second binary diffractive optical elements as said rotating disc rotates,reflecting means to reflect said diffracted light beam from said second binary diffractive optical elements on said rotating disc, such that said reflected light beam is alternately blocked by said alternating blocking elements and diffracted by said alternating second binary diffractive optical elements on said rotating disc as said rotating disc rotates, and said diffracted reflected light beam is alternately blocked and diffracted by said first stationary binary diffractive optical element, andfocussing means to focus said double diffracted, reflected light beam onto a photodetector to generate a synchronization signal for rotation of said rotating disc.

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