US PATENT SUBCLASS 351 / 172
.~.~.~ Multiple elements


Current as of: June, 1999
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351 /   HD   OPTICS: EYE EXAMINING, VISION TESTING AND CORRECTING

41  DF  SPECTACLES AND EYEGLASSES {29}
159  DF  .~ Ophtahalmic lenses or blanks {10}
168  DF  .~.~ Multifocal {4}
172.~.~.~ Multiple elements


DEFINITION

Classification: 351/172

(under subclass 168) Subject matter wherein multiple lens elements of different refractive indices have their adjacent surfaces joined together to provide a unitary multifocal lens that has, for example, a long vision and a reading section.

(1) Note. The modification here comprises for example a major glass member having a shallow countersink and a relatively thin segment fused therein, a thin reading segment fused to a major glass surface, or the lens members may be held in place by usual frame pieces. The countersinks and segments may be of different dimensions and shapes.

SEE OR SEARCH THIS CLASS, SUBCLASS:

168, for multifocal lenses may from a single piece of glass; and 171, for multiple element lenses with three or more foci.