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REMOVING SPECKLE PATTERNS FROM OBJECTS ILLUMINATED WITH A LASER

  • US 3,633,999 A
  • Filed: 07/27/1970
  • Issued: 01/11/1972
  • Est. Priority Date: 07/27/1970
  • Status: Expired due to Term
First Claim
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1. An optical system for reducing speckle resulting from illumination of an object of concern by a coherent continuous wave laser light beam of limited coherence length which comprises:

  • a beam splitter positioned to receive an incident coherent continuous wave laser light beam of limited coherence length for dividing said light beam into first and second coherent beams, said first beam continuing in a line with said incident beam along a first optical path and said second beam directed at an angle with respect to said first beam through a second optical path, a first partially reflective mirror in optical alignment with said beam splitter and spaced therefrom for receiving said first beam and passing said first beam therethrough on the same line, first and second fully reflective mirrors positioned relative to said beam splitter and said partially reflective mirror, respectively, to define said optical path, said first fully reflective mirror receiving said second beam and reflecting said second beam onto said second fully reflective mirror, said second fully reflective mirror reflecting said second beam onto said partially reflective mirror, the length of said optical paths between said beam splitter and said first partially reflective mirror being different by more than said coherence length, said partially reflective mirror reflecting said second beam along the same optical path as said first beam, a second partially reflective mirror in optical alignment with said first partially reflective mirror for receiving a composite beam including said first and said second coherent light beams in which said first and second coherent beams are incoherent with respect to each other, a third fully reflective mirror centered optically on a line with said composite beam, and a fourth fully reflective mirror in optical alignment with said second partially reflective mirror on a line at an angle relative to said composite beam and positioned a distance equal to the distance said third fully reflective mirror is positioned from said second partially reflective mirror, whereby a portion of each beam of said composite beam incident on said second partially reflective mirror is directed to said third fully reflective mirror and a portion is reflected to said fourth fully reflective mirror, said third and fourth fully reflective mirrors reflecting said beams incident thereon back onto said second partially reflective mirrors which recombines said beams into a composite beam and directs said composite beam in a line relative thereto toward an object of interest.

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