Minnesota Mining and Manufacturing Company

Michael J Simpson

John A Futhey

William B Isaacson

A lens according to the invention has diffractive power and two primary foci, where one focus is associated with the first diffractive order and one with the second diffractive order.

Multifocal diffractive ophthalmic lenses

An ophthalmic lens exhibiting diffractive power has a plurality of diffractive zones and smooth surfaces. The zones are arranged such that R.sub.0.sup.2 does not equal R.sub.1.sup.2 -R.sub.0.sup.2 where R.sub.0 is the radius of the central zone and R.sub.1 is the radius of the first annular zone.

Multi-focal diffractive ophthalmic lenses

A multifocal ophthalmic lens has diffractive power produced by a plurality of concentric zones. The zones have radii that meet the condition

A multifocal ophthalmic lens has diffractive power produced by a plurality of concentric zones. The zones have radii that meet the condition R.sub.0.sup.2 &lt;R.sub.1.sup.2 -R.sub.0.sup.2 where R.sub.0 is the radius of the central zone and R.sub.1 is the radius of the first annular zone.

Growing community of inventors

Maplewood, MN, United States of America

Michael J Simpson