Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Ophthalmic lenses or blanks
Patent
1998-06-15
2000-01-11
Sugarman, Scott J.
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Ophthalmic lenses or blanks
351177, G02C 702
Patent
active
060128135
ABSTRACT:
An aspherical lens by which residual aberration in all of third eye-positions is corrected and which the center or edge thickness can be reduced. Thus, this aspherical lens employs a first or second curved surface represented by the following equation: ##EQU1## where (x, y, z) represents the coordinates of a point on an aspherical surface and satisfies (y.epsilon.[a, b]).andgate.(z.epsilon.[c. d]); m.sub.y is an order of a spline function in the direction of the y-axis (in this case, an integer which is not less than 4); m.sub.z is an order of the spline function in the direction of the z-axis (in this case, an integer which is not less than 4); n.sub.y is the number of inner knots in [a, b] in the direction of the y-axis (in this case, an integer which is not less than 4); n.sub.z is the number of inner knots in [c, d] in the direction of the z-axis (in this case, an integer which is not less than 4); N.sub.my,i (y) represents an ith m.sub.y -th-order normalized B-spline function in the case that knots in the direction of the y-axis are .xi..sub.0, .xi..sub.1, .xi..sub.2, . . . , .xi..sub.ny+2my-1 (incidentally, "i" is an integer within [o, n.sub.m +m.sub.y -1] and the position of each knot meets the following condition: .xi..sub.0 .ltoreq..xi..sub.1 .ltoreq.. . . .ltoreq..xi.m.sub.y -1.ltoreq.a<.xi.m.sub.y .ltoreq.. . . .ltoreq..xi..sub.ny+my-1 <b.ltoreq..xi..sub.ny+my .ltoreq.. . . .ltoreq..xi..sub.ny+my+1 ; N.sub.mz,i (z) represents an jth m.sub.z -th-order normalized B-spline function in the case that knots in the direction of the z-axis are .xi..sub.0, .xi..sub.1, .xi..sub.2, . . . , .xi..sub.nz+2mz-1 (incidentally, "j" is an integer within [0, n.sub.z +m.sub.z -1] and the position of each knot meets the following condition: .xi..sub.0 .ltoreq..xi..sub.1 .ltoreq.. . . .ltoreq..xi.m.sub.z -1.ltoreq.c<.xi.m.sub.z .ltoreq.. . . .ltoreq..xi..sub.nz+mz-1 <d.ltoreq..xi..sub.nz+mz .ltoreq.. . . .ltoreq..xi..sub.nz+2mx-1 ; and c.sub.i,j is a coefficient.
REFERENCES:
patent: 5270746 (1993-12-01), Kato et al.
patent: 5479220 (1995-12-01), Komatsu et al.
patent: 5610670 (1997-03-01), Ueno
patent: 5767939 (1998-06-01), Komatsu et al.
Hoya Corporation
Sugarman Scott J.
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