Fractal diffractive lenses with improved diffraction efficiency

In this paper we review the focusing and imaging properties of fractal photon sieves and DevilĀ“s lenses designed in order to improve the diffraction efficiency of fractal diffractive lenses. It is shown that these lenses provide a smoothing effect on the higher order foci of a conventional fractal zone plate. Furthermore, the characteristic self-similar axialesponse of the fractal zone plates is always preserved. This behavior predicts an improved performance of fractal lenses as image forming devices with an extended depth of field and a reduced chromatic aberration.