Dynamic range extension techniques for a wavefront sensor including use in ophthalmic measurement

Abstract

An ophthalmic error measurement system includes a projecting optical system delivering light onto a retina of an eye, a pre-correction system which compensates a light beam to be injected into the eye for aberrations in the eye, the pre-correction system being positioned in between the projecting optical system and the eye, an imaging system which collects light scattered by the retina, and a detector receiving light returned by the retina from the imaging system. Use of the pre-correction system allows the end-to-end aberrations of the ocular system to be analyzed. The use of a pre-correction system also allows use of a minimized spot size on the retina, and all of its attendant advantages.

What is claimed:  
     
         1 . A system for measuring errors in an eye comprising: 
 a projecting optical system which delivers light onto a retina of the eye;    a pre-correction system which compensates a light beam to be injected into the eye for aberrations in the eye, the pre-correction system being positioned in between the projecting optical system and the eye;    an imaging system which collects light scattered by the retina; and    a detector receiving light returned by the retina from the imaging system.    
     
     
         2 . The system of  claim 1 , wherein the detector is a Shack-Hartmann wavefront sensor.  
     
     
         3 . The system of  claim 1 , wherein the detector is a shearing interferometer.  
     
     
         4 . The system of  claim 1 , wherein the detector is a Moiré deflectometer.  
     
     
         5 . The system of  claim 1 , wherein the pre-correction system comprises a telescope having at least one movable lens.  
     
     
         6 . The system of  claim 1 , wherein the pre-correction system comprises fixed lenses inserted at an intermediate image plane.  
     
     
         7 . The system of  claim 1 , wherein the pre-correction system comprises adaptive optical elements.  
     
     
         8 . The system of  claim 1 , wherein the pre-correction system corrects for focus errors in the eye.  
     
     
         9 . The system of  claim 1 , wherein the pre-correction system corrects for focus and astigmatism.  
     
     
         10 . The system of  claim 1 , further comprising an aperture that limits the angular dynamic range of the system.  
     
     
         11 . The system of  claim 1 , further comprising a polarizing beam splitter between the eye and the wavefront sensor.  
     
     
         12 . The system of  claim 1 , further comprising an aligner that determines an appropriate eye alignment of the system.  
     
     
         13 . The system of  claim 1 , wherein the projecting optical system provides light to the eye at an angle to a central axis of the eye.  
     
     
         14 . The system of  claim 1 , further comprising an additional optical system between the detector and the eye.  
     
     
         15 . The system of  claim 1 , further comprising a power monitor which monitors power of the light beam being injected in the eye.  
     
     
         16 . The system of  claim 1 , further comprising an eye position detection system including a target projected on the eye, a position detector sensing the eye, and an adjustment system which adjusts a position of the system relative to the eye until the eye is in focus on the detector.  
     
     
         17 . The system of  claim 1 , wherein the pre-correction system is a cylindrical telescope.  
     
     
         18 . The system of claims  1 , wherein components used in the pre-correction system also are used in the imaging system.  
     
     
         19 . The system of  claim 1 , wherein the pre-correction system includes a feedback loop which determines an appropriate pre-correction to be supplied by the pre-correction system.  
     
     
         20 . The system of  claim 19 , wherein said feedback loop includes a detector receiving light returned from the retina, a processor comparing detected light with a desired feature of the light and adjusting at least one parameter of the pre-correction system in accordance with the comparison.  
     
     
         21 . The system of  claim 20 , wherein said feedback loop further includes a return optical system for gathering the light from the retina.  
     
     
         22 . The system of  claim 21 , wherein said return optical system includes said pre-correction system.  
     
     
         23 . The system of  claim 20 , wherein said desired feature is a minimized spot size on the retina.  
     
     
         24 . The system of  claim 5 , wherein said telescope is arranged so that a fixed lens of the telescope is one focal length away from the eye.