Optimization algorithm for amplitude-only hologram based on digital micromirror device

An optimization algorithm for binary amplitude-only hologram (BAOH) based on the point source method (PSM) with the holographic viewing window (HVW) by using particle swarm optimization (PSO) is proposed. We convert the 256 grayscale levels of each pixel of the original image into an 8-bit binary format and sequentially extract the effective bits of each pixel to generate eight frames of binary original images. Then we introduce random constant phases to be optimized on the wavefront phase of the point source to superimpose the wavefront and generate a grayscale hologram with Burch encoding and binarize it. PSO algorithm is used to search for the optimized constant phase (OCPs) corresponding to each point source wavefront to generate an optimized BAOH. The grayscale representation of the reconstructed image is achieved by sequentially loading eight frames of BAOH on the digital micromirror device (DMD) while controlling the pulse width doubling the illumination of the laser. Simulation results show that the speckle noise of the reconstructed image using the proposed method is significantly suppressed compared with that using the random phase method (RPM), which demonstrates the feasibility of the proposed method.