Defect corrections for coherent optical information processing of grayscale images in a DMD-based 4f-system using a collimated light source

Digital micromirror device (DMD)-based 4f-systems, a type of coherent optical information processing system, have become a powerful tool for optical convolutional neural networks taking advantage of their fast modulation speed and high-resolution capability. However, proper high bit-depth image information processing remains challenging due to the optical diffractions that arise from the binary nature of DMD operation. In this paper, we first characterize the diffraction phenomena that cause irradiance defects, namely the nonlinear grayscale and unintended dark lines. Then to resolve the issues, we propose a DMD operation method and a modified structure of the 4f-system based on blazed diffraction grating theory and numerical calculation of the Rayleigh-Sommerfeld propagation model. As a demonstration, we implement high bit-depth image information processing with an optimized optical 4f-system using DMDs and a collimated coherent light source.

Automated summary

In this paper, we address the issue of optical diffractions caused by the binary nature of DMD operation in coherent optical information processing systems. We characterize the diffraction phenomena and propose a new DMD operation method and modified structure of the 4f-system. We demonstrate the performance of the optimized 4f-system by implementing high bit-depth image information processing.