Holographic Display Apparatus with Focus-Forming Optical Element
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Solution Overview
Problem
Current holographic display technologies face a trade-off between achieving a wide viewing angle and a wide eye box, as the space-bandwidth product of spatial light modulators limits simultaneous expansion of these parameters.
Innovation Solution
The proposed solution involves a holographic display apparatus that includes a focus-forming optical element, a collimating lens, and a spatial light modulator. This configuration allows for the formation of multiple foci and the propagation of light as plane waves, enabling the generation of a holographic image by overlapping these plane waves. Additionally, a gradient descent-based hologram optimization method is used to address the issue of high-order image overlap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of pixels of spatial light modulator is increased to increase both viewing angle and eye box, then the space-bandwidth product is improved, but the manufacturing difficulty and cost increase significantly
Solution Approach 1:
The patent segments the light source into multiple independent laser sources instead of using a single high-pixel-count spatial light modulator. Each laser source corresponds to a specific viewing direction, and multiple such systems are arranged to cover different angular ranges. This segmentation allows achieving wide viewing angle and eye box without manufacturing ultra-high-pixel-density SLMs, thus resolving the contradiction between performance and manufacturability.
2Adaptability or versatility
If time division of multi-light source is used to increase viewing angle and eye box, then the space-bandwidth product is effectively increased, but the device complexity and synchronization requirements increase
Solution Approach 1:
The patent merges multiple spatial light modulators with multiple laser sources into a unified optical system where each SLM-laser pair operates independently for its designated viewing direction. Rather than using time-division multiplexing that requires complex synchronization, the system combines multiple simultaneous spatial channels, each handling a specific angular sector. This merging approach achieves wide viewing angle and eye box while reducing synchronization complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively increases the space-bandwidth product, allowing for a wider viewing angle and eye box without the need for extremely high-speed spatial light modulators or multiple light sources. The hologram optimization method ensures that high-order terms do not overlap within the designated eye box, enabling clear image reproduction.
Implementation Method 1
a focus-forming optical element configured to form a plurality of foci by receiving plane waves
Implementation Method 2
a collimating lens configured to propagate, as plane waves, light incident through the plurality of foci
Implementation Method 3
a spatial light modulator configured to generate a holographic image by overlapping a plurality of plane waves incident from the collimating lens
Data Source
AI summary
A holographic display apparatus and a hologram optimization method for the apparatus are provided. The holographic display apparatus includes a focus-forming optical element configured to form a plurality of foci by receiving plane waves; a collimating lens configured to propagate, as plane waves, light incident through the plurality of foci; and a spatial light modulator configured to generate a holographic image by overlapping a plurality of plane waves incident from the collimating lens.