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.Comment: 14 pages, 9 figures, to be published in SIGGRAPH Asia 202