Progressive multifocal lens and manufacturing method therefor

Details Progressive multifocal lens and manufacturing method therefor Progressive multifocal lens and manufacturing method therefor

1996-06-06

1999-03-23

Sugarman, Scott J.

Optics: eye examining, vision testing and correcting

Spectacles and eyeglasses

Ophthalmic lenses or blanks

351177, G02C 706

Patent

active

058867660

ABSTRACT:
In a process of determining the surface shape of each of progressive multifocal lenses for use as lenses in eyeglasses, radii of curvature at main points are calculated, and then the surface is divided into a plurality of lattice sections, and then a curved-surface equation in the form of a bicubic expression is used for each section to determine the surface shape of the lens. A coefficient of each of the bicubic expressions is determined under a condition that continuation is established to curved-surface equations of sections adjacent at a boundary line between the sections to the derivatives of second order. Therefore, the surface shape of the lens obtained by the curved-surface equation for each section can be formed into a continuous and smooth surface. Since the curved surface can be determined for each section, a partial correction can easily be performed, if necessary. As a result, a progressive multifocal lens can be provided which exhibits smooth astigmatism curves and a large clear field of vision to meet a variety of specifications. Thus, lenses for eyeglasses each having a clear field of vision can be provided.

REFERENCES:
patent: 4514061 (1985-04-01), Winthrop
patent: 4838675 (1989-06-01), Barkan et al.
patent: 4861153 (1989-08-01), Winthrop

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