Lensless computationally defined confocal incoherent imaging with a Fresnel zone plane as coded aperture

Abstract

We present a Fresnel zone plate (FZP) mask-based system for single-shot lensless confocal imaging. The system uses an FZP as coded aperture, which allows each point source to cast a unique pattern onto the sensor, representing their horizontal and axial positions. This results in a 2D sensor measurement comprising a series of FZP patterns, which records the spatial intensity distribution of the incoherent illuminant. The reconstruction process is facilitated by an algorithm based on compress sensing (CS) theory and the use of the nuclear norm of gradient scanning and hologram segmentation technology for autofocusing. The simulative and experimental results of this study align well with the expectation that every layered scene can be accurately recovered at the corresponding depth, without undesirable signals from other layers. Additionally, we analyze the deviation of the reconstruction results in the experiment, which emphasizes the need to consider the thickness of the FZP for a precise forward propagation model.