Polychromatic focusing and imaging properties of tunable multifocal binary Gabor zone plates

In this paper, we introduce tunable binary multifocal Gabor zone plates (TBGZPs) as a novel family of diffractive amplitude lenses designed to create a desired multi-focal distribution. TBGZPs are conceived as a combination of several binary Gabor zone plates with different harmonic terms. We show how this combination can be tailored in the lens design intended to produce multiple foci with tunable intensity and focal lengths. Several examples are presented and evaluated numerically and experimentally. In particular, we introduce a new trifocal binary Gabor zone plate that, under polychromatic illumination, presents an extended depth of focus with low chromatic aberration.