Key points are not available for this paper at this time.
We show that a zone plate with a prespecified number of foci, which are separated axially by Rayleigh's limit of resolution, can create an arbitrarily high focal depth when used as an apodizer over an otherwise clear aperture. We discuss the resolution and light gathering power of this method.
Ojeda‐Castañeda et al. (1990) studied this question.