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Fourier plane recursive optical filter

  • US 4,645,300 A
  • Filed: 07/30/1984
  • Issued: 02/24/1987
  • Est. Priority Date: 07/30/1984
  • Status: Expired due to Fees
First Claim
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1. In an optical recursive filter system of the type having a source of substantially coherent collimated optical radiation, and optical filtering means, said optical filtering means including means for producing an optical Fourier transform, an optical filter, means for producing an optical inverse Fourier transform, said optical filter being located in the focal plane of said Fourier transform producing means, recursive means for directing a beam of radiation from said source in a manner to traverse said optical filtering means a plurality of times such that the attentuation of unwanted spectral frequencies by said filtering means is enhanced, and means for extracting the filtered beam for utilization, the improvement comprising;

  • the arranging of said recursive means in the optical path between said optical Fourier transform means and said optical inverse Fourier transform means such that the recursion of said beam through said optical filter is in the Fourier plane of said optical filtering means whereby the throw of the optical train can be shortened such that the overall size of said system can be reduced.

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