Analytical approach to diffractive multifocal lenses

¹ Bifocon Optics GmbH, Kaerntner Strasse 13-15, 1010 Vienna, Austria
² Lensa GmbH, Suedrandstrasse 15, 1230 Vienna, Austria

Corresponding author: bifocon@magnet.at

Received: 26 October 1999
Revised: 2 January 2000
Accepted: 14 January 2000
Published online: 15 March 2000

Abstract

Diffractive multifocal lenses are usually discussed in terms of geometric zone profiles imparted a surface of a refractive lens. Consequently, the zeroth order diffractive power is usually called the "refractive power" of the diffractive lens. By contrast, we focuss on the refractive power or refractive power profile of the zones of a diffractive lens and calculate the path length error of any of the zones in a given defocus position on the lens axis. From this the phase angle of the resulting amplitudes can be calculated. Analytical expressions for the positions of the diffractive powers as a function of (average) zone powers are derived as well as analytical expressions for the intensities in such positions. Also, general restrictions on usable zone power profiles are derived.