Holographic Rendering Algorithm for Tiled SLM Seam Reduction
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Solution Overview
Problem
Current holographic displays face challenges in providing a large 3-D image with a wide field of view and both horizontal and vertical parallax, due to limitations in spatial light modulator (SLM) pitch and field of view, leading to issues with seam visibility and reduced resolution when tiling multiple SLMs, and the inability to maintain vertical parallax, which is crucial for accurate 3-D perception.
Innovation Solution
A computer-implemented method for computing an array of holographic diffraction patterns by obtaining color images and depth information, creating image layers, encoding spatial information, and adding diffraction patterns to generate holographic images that can be displayed on an angularly-tiled holographic display system, allowing for different fields of view in horizontal and vertical directions and enabling full parallax with view-dependent shading and occlusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple SLMs are tiled together to increase display size or field of view, then the display area or field of view is improved, but visible seams appear in the holographic image due to gaps between SLMs
Solution Approach 1:
The patent introduces an intermediary optical element (lens array or diffractive optical element) between the SLMs and the holographic image plane to optically blend and overlap the images from multiple SLMs. This intermediary component creates angular multiplexing that eliminates visible seams by directing light from adjacent SLMs at overlapping angles, making the transitions between tiled SLMs imperceptible to viewers.
Solution Approach 2:
The patent transitions from spatial tiling in the horizontal plane to angular tiling in the angular domain. By using optical elements that distribute light in different angular directions, multiple SLMs can be arranged in a compact spatial footprint while providing a wide angular field of view, effectively converting a spatial problem into an angular solution that avoids seam visibility.
2Area of stationary object
If the pitch of the SLM is made fine to increase field of view, then the field of view is improved, but the display size must be reduced due to the Lagrange Invariant
Solution Approach 1:
The patent uses angular multiplexing with lens arrays to decouple the relationship between SLM pitch and field of view. Instead of relying solely on fine pitch to achieve wide field of view (which would require small display size per the Lagrange Invariant), the system uses an array of lenses to angularly distribute light from a coarser-pitch SLM, effectively adding an angular dimension that bypasses the traditional spatial trade-off.
Solution Approach 2:
The patent segments the optical system into multiple lens elements, each handling a specific angular portion of the field of view. This segmentation allows the use of a single SLM with moderate pitch to serve multiple angular zones, effectively multiplying the field of view without requiring proportionally smaller display size, as each lens segment independently directs light to its designated viewing zone.
3Area of stationary object
If multiple SLMs are arranged in an arc to increase field of view, then the field of view is improved, but the holographic images overlap in the center with reduced resolution at distances from the SLMs
Solution Approach 1:
The patent assigns different local functions to different regions of the lens array, with each lens element optimized for its specific angular zone. This local quality approach ensures that each portion of the holographic display maintains appropriate resolution characteristics for its designated viewing angle, preventing the central overlap problem by directing each SLM's output to its specific angular region without interference from adjacent SLMs.
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 enables the creation of holographic images with full parallax, accommodating different viewing angles and providing a realistic 3-D experience with improved resolution and reduced seam visibility, suitable for interactive applications and multiple viewers.
Implementation Method 1
Holography is a technique that enables three-dimensional (3-D) images to be generated, recorded, and later displayed. It may involve the use of a laser, interference, diffraction, light intensity and phase recording, and suitable illumination of the recording.
Implementation Method 2
Holography is a technique that enables three-dimensional (3-D) images to be generated, recorded, and later displayed. It may involve the use of a laser, interference, diffraction, light intensity and phase recording
Data Source
AI summary
Algorithms for improved and more efficient rendering of three-dimensional images for use with holographic display systems. These algorithms include creating layers orthogonal to a viewing direction, the separate layers representing different depths in the image. The layers are created based on knowing the color and depth of each point in the image. Each layer then goes through an FFT process until the information for each layer is represented as a diffraction pattern. A holographic lens is then applied to the diffraction pattern of each layer. This lens will cause that layer to appear, in a hologram based thereon, at a different depth than the other layers. The layers, each with their separate lenses, are then coherently summed up and when applied to a suitable portion of a holographic display system (e.g., an SLM), a hologram can be created for that view. A tiled array of such holograms can be combined together by the holographic display system.