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

• Current Assignee: Richard G. Buckles
• Original Assignee: Richard G. Buckles
• Inventors: Buckles, Richard G.
• Primary Examiner(s): Schonberg, David
• Assistant Examiner(s): Stern, Ronald J.
• Application Number:
  US05/058,320
• Time in Patent Office: 533 Days
• Field of Search: 350/3.5,162R,160,163,169,171,172
• US Class Current: 359/577
• CPC Class Codes: G03H 1/32 Systems for obtaining speckle elimination

Abstract

This disclosure is directed to an apparatus and method of removing speckle patterns from objects illuminated with a laser. The laser beam is directed onto or through a beam divider or beam splitter to separate the laser beam into many separate laser beams such that speckle patterns cancel each other when reflected off a surface.

Claims

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.

2. AN optical system for reducing speckle resulting from illumination of an object of concern by a coherent continuous wave laser light beam which comprises:

first, second, and third beam splitters in optical alignment and spaced from each other along a linear line, said first 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 beams, said first beam continuing in a line with said incident beam to said second beam splitter, said second beam directed at an angle relative to said first beam, a first plurality of fully reflective mirrors positioned relative to said first beam splitter in optical alignment for reflecting said second beam along an optical path which is longer in length than said first beam path by a distance greater than the coherence length of said continuous beam and reflecting said second beam back onto said first beam splitter along a continuous optical path, said first beam splitter reflecting said second beam along the same optical path as said first beam to said second beam splitter, said second beam splitter dividing said first beam into third and fourth beams and said second beam into fifth and sixth beams, said third and fifth beams continuing through said second beam splitter to said third beam splitter, said fourth and sixth beams being reflected at an angle relative to said third and fifth beams, a second plurality of fully reflective mirrors positioned relative to said second beam splitter in optical alignment for reflecting said fourth and sixth beams back onto said second beam splitter along a continuous optical path, said second beam splitter reflecting said fourth and sixth beams along the same optical path as said third and fifth beams to said third beam splitter, said third beam splitter dividing the incident beams into 2n beams, where n is the number of beams incident thereon, said third beam splitter passing n number of beams therethrough along a line and reflecting n number of beams at an angle relative thereto, said beams reflected at an angle relative to said third beam splitter being optically reflected back onto said third beam splitter being optically reflected back onto said third beam splitter and reflected thereby along the same optical path with said n number of beams passed therethrough, all said different light paths differing in length by a distance greater than the coherence length of said continuous wave laser beam, whereby the combined 2n beams are directed along the same optical path onto an object to be illuminated with the individual beams being coherent but incoherent with respect to each other.