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Display Systems

Use this section when the algorithm is not the whole story and the display system itself becomes the bottleneck.

Quick map:

  • Speckle Noise Reduction: reduce coherent artifacts and improve image quality.
  • Perception-related Research: optimize the hologram for what observers actually see and accommodate to.
  • Etendue Expansion: trade off field of view and eyebox size.
  • Holographic Optical Elements (HOEs): use holographic optics inside the display stack.
  • Small Form-factor Displays: reduce bulk for practical AR/VR hardware.
  • Compression: lower bandwidth and computation costs.
  • Zero or Higher Diffraction Orders Optimization: manage unwanted orders or exploit higher ones.

Speckle Noise Reduction

Speckle noise is a result of interference among coherent waves, which is often present in holographic images since holographic displays use coherent laser sources. Methods for reducing speckle noise can roughly be catergorized into the following:

Time-averaging

Partially-coherent Light Sources

Others

Perception-aware holography work studies which image errors matter to human observers, how focus and accommodation cues should be optimized, and how gaze-contingent or metameric losses can trade exact reconstruction for better visual quality.

Etendue Expansion

The product of the field of view (FoV) and the eyebox size, the etendue, is limited by the number of pixels on the SLM. Hence, there is an inherent tradeoff between these two properties.

Holographic Optical Elements (HOEs)

Small Form-factor Displays

Bulky headsets hamper the development of AR/VR. Reducing the size of holographic displays are important:

Compression

CGH compression is also important for deploying holography technology on edge devices:

Zero or Higher Diffraction Orders Optimization

  • Unfiltered holography: optimizing high diffraction orders without optical filtering for compact holographic displays (Gopakumar et al. 2021 | Optics Letters, Optica) incorporated higher diffraction orders into the CGH optimization procedure to remove the 4f filtering system often used in holographic displays, thus reducing the display form factor.
  • Elimination of a zero-order beam induced by a pixelated spatial light modulator for holographic projection (Zhang et al. 2009 | Applied Optics, Optica)
  • Holographic projection of arbitrary light patterns with a suppressed zero-order beam
  • Effect of spurious diffraction orders in arbitrary multifoci patterns produced via phase-only holograms
  • Off-axis camera-in-the-loop optimization with noise reduction strategy for high-quality hologram generation (Chen et al. 2022 | Optics Letters, Optica)