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.

1 . A system for measuring errors in an eye, comprising:
 a projecting optical system configured to focus light onto a retina of the eye;   an imaging system configured to receive light from the projecting optical system that is scattered by the retina;   a wavefront sensor configured to receive light returned by the retina from the imaging system; and   a target and a target optical system configured to project the target onto the eye so as to stimulate near vision accommodation of the eye.   
   
   
       2 . The system of  claim 1 , wherein a relative distance between the target and the optical system is variable. 
   
   
       3 . The system of  claim 1 , wherein the target is moveable relative to the target optical system. 
   
   
       4 . The system of  claim 1 , further comprising a light source disposed behind the target, a brightness of the light source being electronically adjustable. 
   
   
       5 . The system of  claim 1 , further comprising a pre-correction system configured to compensate a light beam to be injected into the eye for aberrations in the eye. 
   
   
       6 . The system of  claim 3 , wherein the pre-correction system is positioned in between the projecting optical system and the eye. 
   
   
       7 . The system of  claim 1 , wherein the system is configured to measure near vision visual acuity. 
   
   
       8 . The method of  claim 1 , wherein the target optical system comprises a lens. 
   
   
       9 . The method of  claim 8 , wherein the lens is a variable focal length lens. 
   
   
       10 . A method of measuring optical characteristics of an eye, comprising:
 providing a measurement system including:
 a projecting optical system; 
 an imaging system for receiving light scattered by the retina; 
 a wavefront sensor; and 
 a target system comprising a target and a target optical system; 
 projecting the target onto the eye; 
 stimulating near vision accommodation of the eye; 
 directing light from the light source onto a retina of the eye; 
 receiving in the imaging system light scattered by the retina; 
 receiving in the wavefront sensor the light received by the imaging system; and 
 measuring a near vision visual acuity of the eye. 
   
   
   
       11 . The method of  claim 9 , wherein stimulating near vision accommodation includes varying an optical distance between the target and the eye. 
   
   
       12 . The method of  claim 9 , wherein stimulating near vision accommodation includes moving the target relative to the target optical system. 
   
   
       13 . The method of  claim 9 , wherein the target optical system comprises a lens. 
   
   
       14 . The method of  claim 13 , wherein the lens is a variable focal length lens. 
   
   
       15 . A system for measuring errors in an eye, comprising:
 a projecting optical system configured to focus light onto a retina of the eye;   an imaging system configured to receive light from the projecting optical system that is scattered by the retina;   a wavefront sensor configured to receive light returned by the retina from the imaging system;   a target and a target optical system configured to project an optical image of the target onto the eye;   wherein an optical distance between the target and the eye is variable so as to allow measurement of near vision visual acuity.   
   
   
       16 . The system of  claim 15 , wherein the target is configured to stimulate near vision accommodation of the eye. 
   
   
       17 . The system of  claim 15 , wherein the target is configured to be located so as to minimize accommodation of the eye. 
   
   
       18 . The system of  claim 15 , wherein the target optical system comprises a lens. 
   
   
       19 . The system of  claim 18 , wherein the lens is a variable focal length lens.