Apparatus and method for measuring vision defects of a human eye

Abstract

An apparatus for measuring vision characteristics of an eye includes a laser for providing an optical beam and a focusing element for focusing the optical beam behind a retina of the eye for providing a finite source of secondary radiation on the retina of the eye. The secondary radiation is emitted from the retina as a reflected wavefront of radiation that passes outward from the eye. A polarizer is placed within a path of the optical beam for transmitting a polarized wavefront therethrough. A wavefront analyzer receives the polarized wavefront for measuring distortions associated therewith.

That which I claimed I:  
     
         1 . An apparatus for measuring vision characteristics of an optical system, the apparatus comprising: 
 focusing means for focusing an optical beam proximate a posterior surface of the optical system for providing a finite source of secondary radiation on a focal surface, the posterior surface other than the focal surface, which secondary radiation is emitted from the focal surface as a reflected wavefront of radiation that passes through the optical system;    directing means for directing the reflected wavefront onto a wavefront analyzer; and    a wavefront analyzer for measuring distortions associated with the reflected wavefront.    
     
     
         2 . The apparatus recited in  claim 1 , wherein the focusing means comprises a long-focal-length lens for converging the optical beam through a small angle and focusing the optical beam on the anterior surface.  
     
     
         3 . The apparatus recited in  claim 2 , wherein the long-focal-length lens has a focal length of at least one-half meter.  
     
     
         4 . The apparatus recited in  claim 1 , wherein the focusing means comprises a zoom lens for converging the optical beam through a small angle and varying the focusing of the optical beam onto various anterior surfaces.  
     
     
         5 . The apparatus recited in  claim 1 , further comprising a laser for providing the optical beam.  
     
     
         6 . The apparatus recited in  claim 1 , further comprising the a shutter operable from a closed position to an open position for controlling an amount of optical beam energy delivered to the optical system.  
     
     
         7 . The apparatus recited in  claim 1 , wherein the wavefront analyzer comprises: 
 an opaque plate having an aperture therein for transmitting a portion of the emitted wavefront therethrough; and    a light-sensitive material downstream of and in spaced relation to the opaque plate for receiving the portion of the reflected wavefront projected as a finite image thereon.    
     
     
         8 . The apparatus recited in  claim 7 , wherein the aperture comprises an aperture array and wherein the light-sensitive material comprises a CCD array.  
     
     
         9 . The apparatus recited in  claim 8 , further comprising a lens carried within each of the plurality of apertures of the aperture array.  
     
     
         10 . The apparatus recited in  claim 1 , further comprising polarizing means for polarizing the optical beam.  
     
     
         11 . The apparatus recited in  claim 10 , further comprising a polarization beamsplitter for reflecting an S-component of the reflected wavefront and for transmitting a P-component of the reflected wavefront as a polarized wavefront therethrough.  
     
     
         12 . The apparatus recited in  claim 1 , further comprising a camera positioned for viewing the focal surface.  
     
     
         13 . An apparatus for measuring vision characteristics of an eye, the apparatus comprising: 
 a laser for providing an optical beam;    focusing means for focusing the optical beam behind a retina of the eye for providing a finite source of secondary radiation on the retina of the eye, which secondary radiation is emitted from the retina as a reflected wavefront of radiation that passes outward from the eye;    polarizing means placed within a path of the optical beam for transmitting a polarized wavefront therethrough; and    a wavefront analyzer receiving the polarized wavefront for measuring distortions associated therewith.    
     
     
         14 . The apparatus recited in  claim 13 , wherein the focusing means comprises a long-focal-length lens for converging the optical beam through a small angle and focusing the optical beam on the anterior surface.  
     
     
         15 . The apparatus recited in  claim 14 , wherein the long-focal-length lens has a  15  focal length of approximately one-half meter.  
     
     
         16 . The apparatus recited in  claim 13 , further comprising the a shutter operable from a closed position to an open position for controlling an amount of optical beam energy delivered to the eye.  
     
     
         17 . The apparatus recited in  claim 13 , wherein the wavefront analyzer comprises: 
 an opaque plate having an aperture therein for transmitting a portion of the emitted wavefront therethrough; and    a light-sensitive material downstream of and in spaced relation to the opaque plate for receiving the portion of the reflected wavefront projected as a finite image thereon.    
     
     
         18 . The apparatus recited in  claim 17 , wherein the aperture comprises an aperture array and wherein the light-sensitive material comprises a CCD array.  
     
     
         19 . The apparatus recited in  claim 18 , further comprising a lens carried within each aperture of the aperture array.  
     
     
         20 . The apparatus recited in  claim 13 , further comprising a fixation target for viewing by a patient whose eye is being measured, the fixation target assuring that a patient whose eye is being measured is looking along a preferred direction.  
     
     
         21 . The apparatus recited in  claim 13 , further comprising a camera positioned for viewing the focal surface.  
     
     
         22 . A method for measuring vision defects of an eye comprising the steps of: 
 focusing an optical beam anterior of the retina of the eye, but not on the retina, for placing a finite source of secondary radiation on the retina, which secondary radiation is emitted from the retina as a reflected wavefront of radiation that passes through the eye;    projecting the reflected wavefront onto a wavefront analyzer; and    measuring distortions associated with the reflected wavefront.