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Laser light beam homogenizer and imaging lidar system incorporating same

  • US 5,303,084 A
  • Filed: 08/27/1991
  • Issued: 04/12/1994
  • Est. Priority Date: 08/27/1991
  • Status: Expired due to Term
First Claim
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1. In a laser light beam homogenizer having diverging means for diverging a light beam with spatially inhomogeneous intensity, said light having a coherence length LC with said diverging means providing a diverging light beam, integrator means having a first aperture for receiving said diverging light beam and having a plurality of internally reflective surfaces for forming an array of apparent light sources, the light from each apparent source in said array being superposed by said integrator means at a second aperture thereof, each individual light ray from each apparent source following a distinct light path to said second aperture to provide a uniform illumination beam, and minimum path length difference means for providing a minimum path length difference between the individual path lengths of any two rays coincident at said second aperture and arising from adjacent apparent sources in said array, said minimum path length difference means being at least said coherence length LC of said beam, wherein the improvement comprises:

  • control optics means for receiving said uniform illumination beam from said integrator means, said control optics means for reducing the divergence and the radiance of said uniform illumination beam, said control optics means providing a controlled beam;

    wherein said control optics means comprises;

    (1) first lens means having a first pair of opposed optical surfaces, one of said first surfaces receiving said uniform illumination beam, said first lens means reducing the divergence of said uniform illumination beam and providing a reduced divergence uniform beam; and

    (2) second lens means having a second pair of opposed optical surfaces, one of said second surfaces being disposed adjacent to one of said first surfaces for receiving said reduced divergence uniform beam, said second lens means providing said controlled beam and controlling higher order distortion in said controlled beam; and

    wherein said first lens comprises a plano-convex lens, whereby one of said first surfaces is convex and one of said first surfaces is flat; and

    wherein said second lens comprises an aspheric lens.

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