Multisource Holography

TL;DR

This paper introduces multisource holography, a novel approach using multiple sources and sequential modulators to suppress speckle noise in holographic displays without sacrificing resolution, validated through simulations and experiments.

Contribution

The paper presents a new multisource holography architecture and algorithm that effectively reduces speckle noise in holographic images without compromising resolution.

Findings

Achieved up to 10 dB increase in peak signal-to-noise ratio.

Demonstrated suppression of speckle noise in 2D and 3D holographic images.

Validated the approach with a benchtop prototype.

Abstract

Holographic displays promise several benefits including high quality 3D imagery, accurate accommodation cues, and compact form-factors. However, holography relies on coherent illumination which can create undesirable speckle noise in the final image. Although smooth phase holograms can be speckle-free, their non-uniform eyebox makes them impractical, and speckle mitigation with partially coherent sources also reduces resolution. Averaging sequential frames for speckle reduction requires high speed modulators and consumes temporal bandwidth that may be needed elsewhere in the system. In this work, we propose multisource holography, a novel architecture that uses an array of sources to suppress speckle in a single frame without sacrificing resolution. By using two spatial light modulators, arranged sequentially, each source in the array can be controlled almost independently to create a version of the target content with different speckle. Speckle is then suppressed when the contributions from the multiple sources are averaged at the image plane. We introduce an algorithm to calculate multisource holograms, analyze the design space, and demonstrate up to a 10 dB increase in peak signal-to-noise ratio compared to an equivalent single source system. Finally, we validate the concept with a benchtop experimental prototype by producing both 2D images and focal stacks with natural defocus cues.