Practical design of a bifocal hologram contact lens or intraocular lens.

When designing diffractive lenses, a high-diffraction efficiency at a particular design wavelength is often the most important criterion. Recently it has become of interest to consider lens designs that split incident light predominantly into two orders for use as bifocal contact lenses or intraocular lenses. Surface- relief profiles on contact and intraocular lenses are subject to many practical constraints in addition to requiring high efficiencies at the two focal points. A new lens design combining a binary-amplitude absorption profile with a unique nonparabolic surface-relief profile is proposed to satisfy these constraints.