Lensless imaging via multi-height mask modulation and ptychographical phase retrieval

Abstract

Multi-height phase retrieval by adding a thin diffuser between the object and the detector has emerged as an effective approach for lensless imaging. However, up to 100 measurements are required to jointly recover the object and diffuser, which makes the data acquisition time-consuming and cumbersome. In this paper, we report a novel multi-height lensless imaging technique. In our scheme, the diffuser is replaced with a random binary amplitude mask and placed upstream of the object to introduce speckle illumination. Multiple diffraction patterns are then recorded by moving the mask axially, while the object and the detector remained stationary. Inspired by the ptychography, the extended ptychographic iterative engine algorithm is adopted to reconstruct the object and the unknown mask simultaneously. The imaging performance is first validated by simulation and then experimentally tested with resolution target, phase plate, and biological sample. Compared with the original method, the proposed method can achieve high-quality reconstruction with as few as ∼20 images, which greatly accelerates the data acquisition and reconstruction.