Analytical approach to diffractive multifocal lenses

Diffractive multifocal lenses are usually discussed in terms of geometric z one profiles imparted a surface of a refractive lens. Consequently, the zer oth order diffractive power is usually called the "refractive power" of the diffractive lens. By contrast, we focuss on the refractive power or refrac tive power profile of the zones of a diffractive lens and calculate the pat h 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 calculat ed. Analytical expressions for the positions of the diffractive powers as a function of (average) zone powers are derived as well as analytical expres sions for the intensities in such positions. Also, general restrictions on usable zone power profiles are derived.