Speckle suppression in holographic displays using temporal averaging effect combined with rotating symmetric diffuser

The speckle noise will seriously influence the quality of reconstructed images in holographic displays based on spatial light modulators (SLMs). In order to suppress the speckle noise quickly, we propose a method which combines temporal averaging effect by superposing multi sub-frame images and adding a rotating symmetric diffuser in optical path. The sub-frame images are reconstructed from sequential sub-frame kinoforms. The sequential kinoforms are calculated using Fresnel diffraction based algorithm by adding dynamic pseudorandom initial phase factors. A rapidly rotating symmetric diffuser is replaced the pinhole in optical path to produce illumination light sources with various speckle patterns over a short periods of time. Hence, various holographic images with different speckle patterns can be reconstructed and superposed to reduce the speckle noise. Optical reconstructions with a phase-only SLM show that, with the proposed method, the speckle noises are well suppressed by superposing fewer sub-frame images compared to use temporal averaging method only. The proposed method is useful for improving the quality of reconstructions in holographic displays with pixelated SLMs.