Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Ophthalmic lenses or blanks
Reexamination Certificate
2000-10-11
2001-12-04
Schwartz, Jordan M. (Department: 2873)
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Ophthalmic lenses or blanks
Reexamination Certificate
active
06325510
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to progressive multifocal lens constructions for use in eyeglasses.
BACKGROUND OF THE INVENTION
Progressive multifocal lenses as used in eyeglasses, or spectacles, comprise, along a principle meridian curve; a farsighted vision zone having an optical power corresponding to that required for viewing distant objects; a nearsighted vision zone having an optical power corresponding to that required for viewing near objects; and an intermediate vision zone between and progressively connecting the farsighted vision zone and the nearsighted vision zone. Progressive eyeglasses thus ensure different optical powers in upper and lower portion of each spectacle lens gradually increasing towards the lower periphery. However, strong problems with aberration correction exist. The oblique rays of near objects pass through the spectacle lens at peripheral parts such that they usually produce astigmatism and/or other aberrations. The degree of astigmatism is also high for the right and left peripheral parts of the spectacle lens responsible for side vision, thus loosing comfort in vision.
Traditional technology for spectacles lens fabrication based on refractive optics provides very limited possibilities in aberration correction. The important parameters: optical power, near and far vision ability, lens thickness, and aberration rate, are in a tradeoff relation and cannot be achieved all together. For example changing the local slope of the lens surface for aberration correction immediately influences lens thickness and might change also optical powers for far or/and near vision.
OBJECTS AND BRIEF SUMMARY OF THE INVENTION
An object of the present invention is to provide progressive multifocal lenses for eyeglasses having advantages in the above respects. Another object of the invention is to provide progressive multifocal lenses for eyeglasses which are not subject to the above-described limitations for correcting astigmatism and/or other abberations.
According to a broad aspect of the present invention, there is provided a progressive multi-focal lens comprising the three vision zones mentioned above common to all progressive lenses, but characterized in that at least one of the vision zones includes a transparent, non-rotationally-symmetrical, diffractive microrelief structure.
Diffractive optics opens new possibilities in eyeglass lens development. Diffractive lenses and aberration correctors work on the principle of light diffraction, rather than on light refraction. It is very promising and cost efficient to consider hybrid refractive diffractive optical components. Mechanical sizes of hybrid lens are almost the same as for refractive-only lens, because diffractive portion have the thickness of few microns. The diffractive portion of a hybrid refractive-diffractive lens would be just the microrelief pattern coated, etched or diamond turned on one of the lens surfaces which serves as a substrate for the diffractive pattern.
Diffractive optics have been used in contact and intraocular bifocal lenses, as described for example in Allen L. Cohen U.S. Pat. No. 4,995,714, Allen L. Cohen U.S. Pat. No. 4,162,122, Allen L. Cohen U.S. Pat. No. 4,210,391, Allen L. Cohen U.S. Pat. No. 4,338,005, and Allen L. Cohen U.S. Pat. No. 4,340,283, which patents are hereby incorporated by reference. However, in so far as we are aware, diffractive optics have not yet been used in progressive multifocal lenses for eyeglasses, in which the diffractive structure in the zones is not rotationally symmetrical.
Further features and advantages of the invention will be apparent from the description below.
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Wilfrid B. Veldkamp and Thomas J. McHugh, “Binary Optics”, Scientific American, May 1992, pp. 50-55.
Golub Michael
Grossinger Israel
Eitan Pearl Latzer & Cohen-Zedek
Holo or Ltd.
Schwartz Jordan M.
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