Study of superresolution with annular filters

Abstract

Characteristics of superresolution effect of annular amplitude and phase filters are compared in this paper. Numerical simulations show that the phase type filter can achieve the superresolution effect, the circular Dammann effect, the flat-top intensity, and doughnut pattern for different applications, while the two-zone amplitude filter does have the capability of generating the superresolution effect but it cannot generate the circular Dammann effect, doughnut and the flat-top intensity. Two-zone and three-zone phase and amplitude type pupil filters are analyzed in theory and implemented in experiment. The experimental results show that both amplitude and phase filters can achieve superresolution effects evidently. The advantage of an amplitude style filter is that the fabrication technology is much simpler than that for a pure-phase one. The amplitude filter can only be used for the specific superresolution cases where the energy utilization ratio is not the main issue. Generally, the pure-phase superresolution filter is recommended for its higher efficiency and, more importantly, it can achieve special diffraction patterns that are impossible to achieve with an amplitude filter.