Single-shot phase reconstruction based on beam splitting encoding and averaging

Abstract

Coherent modulation imaging (CMI) can effectively improve the convergence performance of coherent diffraction imaging by introducing a pre-characterized wave modulator. However, traditional CMI algorithms suffer from a low signal-to-noise ratio (SNR), with insufficient information redundancy inheriting from a single diffraction pattern. Additionally, the strong modulation capability of the modulator with a small basic pitch is preferred; however, it leads to the difficulty of fabrication and measurement with a limited aperture size of the detector. To overcome those obstacles, this study proposes a revised CMI algorithm based on beam splitting encoding and averaging. A diffraction pattern array was recorded after the incident wave was split by grating and modulated by a weak scattering modulator simultaneously. This approach differed from the previous grating-based single-shot phase retrieval algorithm because the diffraction array was not segmented and used integrally during the iteration process, which guarantees the capability of diffraction-limited resolution in theory. Additionally, an average process was employed in the image plane of the object to improve SNR significantly. The performance of the revised algorithm was demonstrated by simulations and experiments and can be applied as a universal single-shot phase retrieval algorithm to various fields practically with fast convergence speed and high SNR.