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Conoscopic system for real-time corneal topography

  • US 5,909,270 A
  • Filed: 05/09/1997
  • Issued: 06/01/1999
  • Est. Priority Date: 05/10/1996
  • Status: Expired due to Fees
First Claim
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1. A conoscopic topographer for obtaining topographic measurements of a substantially spherical target surface at a fixed position, comprising:

  • an illuminating device, producing a collimated probe beam to said target surface, said probe beam being of a probe wavelength to which said target surface is reflective;

    a collecting lens disposed relative to said target surface at a predetermined distance, for receiving a reflected probe beam including said target surface, said reflected probe beam encoded with surface phase information indicative of said target surface;

    an optical birefringent medium having a single optic axis, positioned relative to said collecting lens and oriented to form a tilted angle between a direction of said reflected probe beam and said optic axis, said birefringent medium splitting said reflected probe beam into an ordinary probe beam and an extraordinary probe beam which interfere with each other to form a conoscopic interference pattern;

    a first polarizer, located in an optical path of said probe beam between said light source and said birefringent medium, operating to polarize said reflected probe beam in a first polarization direction;

    an imager, receiving said conoscopic interference pattern and producing an electrical representation of said interference pattern; and

    a microprocessor, processing said electrical representation of said interference pattern to extract a topographic shape of said target surface.

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