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AssigneeNone recorded
InventorsDenwood F. Ross, Michael Schottner, Bjorne Baschek, Josef Bille
Estimating the term…
Defocus and astigmatism compensation methods and apparatuses for use in an aberration measurement system. The apparatuses including reflectors for altering the optical distance between a pair of lenses passing a wavefront without changing the physical distance between the lenses, thereby compensating for defocus in the wavefront; and cylindrical mirrors for adding and removing curvature from a curved wavefront, thereby compensating for astigmatism in the wavefront. The methods including passing a wavefront having defocus through a first lens on a first path, reflecting the wavefront from the first path to a second path, reflecting the wavefront from the second path to a third path, and passing the wavefront through a second lens as a defocus compensated wavefront; and passing a wavefront through first and second cylindrical lens, and orienting the first and second cylindrical lenses with respect to the wavefront and to one another to compensate for astigmatism in the wavefront.
In an ophthalmic system for measuring eye aberrations having first and second optical lenses separated by a physical distance for focusing a wavefront, a method of adjusting the optical distance between the two lenses without changing the physical distance between the two lenses, the method comprising the following:
In an ophthalmic system for measuring eye aberratons having first and second optical lenses separated by a physical distance for focusing a wavefront, a method of adjusting the optical distance between the two lenses without changing the physical distance between the two lenses, the method comprising the following:
A method for removing astigmatism from a wavefront in an ophthalmic system for measuring eye aberrations, the method comprising the following:
In an ophthalmic system for measuring eye aberrations having first and second optical lenses separated by a physical distance for focusing a wavefront, an apparatus for adjusting the optical distance between the two lenses without changing the physical distance between the two lenses, the apparatus comprising:
In an ophthalmic system for measuring eye aberration, an apparatus for correcting astigmatism in a wavefront, said apparatus comprising:
Dependencies are inferred from the claim text.
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Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions: for wavefront analysis
Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions: for determining refraction, e.g.…
Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00: for optical correction, e.g. distorsion,…
Medical diagnosis and surgery
Term ended 27 Apr 2021 (estimated)
The present invention relates generally to optical instruments and, more particularly, to a method and device for defocus and astigmatism compensation in wavefront aberration measurement systems. The present invention is particularly useful, but not exclusively so, for defocus and astigmatism compensation in ophthalmic applications.
The human eye is an optical system employing several lens elements to focus light rays representing images onto the retina within the eye. The sharpness of the images produced on the retina is a factor in determining the visual acuity of the eye. Imperfections within the lens and other components and material within the eye, however, may cause the light rays to deviate from the desired path. These deviations, referred to as aberrations, result in blurred images and decreased visual acuity. Hence, methods and apparatuses for measuring aberrations are desirable to aid in the correction of such problems.
One method of detecting aberrations introduced by the eye involves determining the aberrations of light rays exiting from the eye. A beam of light directed into the eye as a point on the retina is reflected or scattered back out of the eye as a wavefront, with the wavefront containing aberrations introduced by the eye. By determining the propagation direction of discrete portions (i.e., samples) of the wavefront, the aberrations introduced by the eye can be determined and corrected.
FIG. 1 is a schematic of a wave produced by a laser beam reflected by the retina of an eye;
FIG. 2 is a schematic of a prior art apparatus for measuring aberrations introduced by an eye;
FIG. 3 is a schematic of a part of a prior art defocus compensation device;
Illustrated in FIG. 6 is a preferred embodiment of a wavefront measuring apparatus 100 for measuring the aberrations of an eye 16 in accordance with the present invention. In a general overview, a beam 12 is generated by a laser 22 and directed by a beam splitter 24 into the eye 16. The diameter of the beam 12 is small, thereby minimizing the effect of optical components between the laser 22 and the eye 16 on the beam 12. A wavefront 10 is reflected out of the eye toward a wavefront sensor 26 for measurement of aberrations introduced to the wavefront 10 by the eye 16.
If the wavefront 10 contains a relatively large amount of defocus or astigmatism, portions of the wavefront 10 may not reach the wavefront sensor 26 or may be out of range for measurement by the wavefront sensor 26. Therefore, the wavefront 10 is passed through a novel defocus compensation device 102 and through a novel astigmatism compensation device 104 to compensate for relatively large defocus and astigmatism, respectively, within the wavefront 10.
The defocus compensation device 102 adds a defocus compensation component to the wavefront 10, and the astigmatism compensation device 104 adds an astigmatism compensation component to the wavefront 10. Remaining aberrations within the wavefront 10, after defocus and astigmatism compensation, are then detected by the wavefront sensor 26. The processor 27 then determines the aberrations of the wavefront 10 based of the information obtained from the wavefront sensor 26, the defocus compensation component added by the defocus compensation device 102, and the astigmatism compensation component added by the astigmatism compensation device 104.