Ophthalmic instrument having Hartmann wavefront sensor with extended source
First Claim
1. An ophthalmic instrument comprising:
- an extended source producing light that is formed as an image on the retina of a human eye and reflected from said human eye to produce retinal reflections derived from said extended source; and
a wavefront sensor for estimating aberrations in said retinal reflections, wherein said wavefront sensor comprises;
a plurality of subapertures that form a plurality of images of the extended source from said retinal reflections;
an imaging device that captures said plurality of images and outputs image data representing said images; and
an image processing computer that generates an estimate of the gradient field of said retinal reflections by applying image correlation techniques in the digital domain to said image data.
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Accused Products
Abstract
An improved ophthalmic instrument including an extended source producing light that is formed as an image on the retina of the human eye and reflected there from to produce retinal reflections derived from the extended source, and a wavefront sensor that estimates aberrations in the retinal reflections. The wavefront sensor includes a plurality of subapertures that form a plurality of images of the extended source from the retinal reflections, an imaging device that captures the plurality of images and outputs image data representing the images, and an image processing computer that generates an estimate of the gradient field of the retinal reflections by applying image correlation techniques in the digital domain to the image data. The image processing computer preferably generates an estimate of the local tilt of the retinal reflections incident on a given subaperture by deriving a correlation product for a given image formed by the given subaperture and identifying a peak correlation point of the correlation product. The dimensions of the image of the extended source formed on the retina of the human eye is preferably larger than a diffraction limited spot yet small enough so that different parts of the image do not experience substantially different aberrations while passing through the eye. In addition, the angular size of the image of the extended source is preferably limited so that the plurality of images formed by the subapertures do not overlap.
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Citations
19 Claims
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1. An ophthalmic instrument comprising:
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an extended source producing light that is formed as an image on the retina of a human eye and reflected from said human eye to produce retinal reflections derived from said extended source; and
a wavefront sensor for estimating aberrations in said retinal reflections, wherein said wavefront sensor comprises;
a plurality of subapertures that form a plurality of images of the extended source from said retinal reflections;
an imaging device that captures said plurality of images and outputs image data representing said images; and
an image processing computer that generates an estimate of the gradient field of said retinal reflections by applying image correlation techniques in the digital domain to said image data. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification