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Endoscopic imaging system employing diffractive optical elements

  • US 5,980,454 A
  • Filed: 12/01/1997
  • Issued: 11/09/1999
  • Est. Priority Date: 12/01/1997
  • Status: Expired due to Term
First Claim
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1. An objective for an endoscope, said objective intended to form an image in an image plane, said objective comprising:

  • a first distal optical element, adapted to be disposed between an object and an aperture stop,an aperture stop, for absorbing rays of light passing through portions of said distal optical element other than from corresponding predetermined portions of the object, anda second proximal optical element, adapted to be disposed between said aperture stop and an imaging element, wherein;

    a number of grooves spaced from one another by between about 10 and about 100 wavelengths of visible light are formed on at least one of distal or proximal surfaces of said distal and proximal optical elements, constituting said surface a diffractive surface;

    said at least one diffractive surface is spaced well away from said aperture stop, said aperture stop being located with respect to said diffractive surface and having a pupil diameter such that only rays incident on particular limited areas on the diffractive surface from said corresponding predetermined portions of the object can reach corresponding points on the imaging surface; and

    the depth and spacing of the grooves in said at least one diffractive surface varying with radial distance from the optical axis.

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