Aperture Expansion in Light Field Displays via Grating Interferometer
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Solution Overview
Problem
Current 3D display technologies, such as volumetric, holographic, and Light Field (LF) displays, face challenges including low resolution, large physical size, high manufacturing costs, and limitations in providing correct retinal focus cues, leading to suboptimal 3D experiences due to diffraction effects and limited angular resolution.
Innovation Solution
The implementation of a grating interferometer and Spatial Light Modulator (SLM) structure that enlarges the aperture size of LF display pixels, reducing diffraction effects and increasing angular resolution, allowing for higher resolution displays and larger eyeboxes without affecting spatial resolution on the display surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the aperture size of LF display pixels is increased, then diffraction effects are reduced and angular resolution is improved, but the physical size of the display device increases
Solution Approach 1:
The patent introduces a super-resolution lens that operates in the angular dimension rather than simply increasing the physical aperture diameter. By using a lens with a large diameter and short focal length, the system achieves aperture expansion in the angular domain while maintaining compact physical dimensions. The lens maps angular information to spatial positions, effectively increasing the usable aperture without proportionally increasing the display device footprint.
Solution Approach 2:
The patent changes the optical parameters of the system by introducing a super-resolution lens with specific characteristics (large diameter, short focal length). This lens modifies the light paths and aperture characteristics to achieve higher angular resolution. The lens parameters are optimized to expand the effective aperture while controlling the overall device size, resolving the contradiction between resolution and compactness.
2Reliability
If multiple views are presented to create light fields, then retinal focus cues are improved, but diffraction blur increases and spatial resolution decreases
Solution Approach 1:
The super-resolution lens acts as an intermediary optical element between the light field generator and the viewer's eye. It mediates the trade-off between multiple view presentation and resolution by expanding the aperture in a controlled manner. The lens processes the light fields to maintain spatial resolution while enabling the multiple view configuration that provides correct retinal focus cues.
Solution Approach 2:
The patent optimizes optical parameters including the lens diameter, focal length, and positioning to achieve the desired balance. By carefully selecting these parameters, the system maintains high spatial resolution while presenting multiple views for accurate retinal focus. The parameter optimization ensures that diffraction blur is minimized despite the complex multi-view configuration.
3Ease of operation
If Super Multi View techniques are used with 512 views, then smooth transitions between viewpoints are achieved, but device complexity and manufacturing costs increase
Solution Approach 1:
The patent extracts the complexity management function to a dedicated optical component - the super-resolution lens. Rather than managing 512 views through complex software or multiple independent display systems, the optical lens simplifies the presentation of multiple views by physically separating and organizing the light paths. This extraction of complexity to an optical element reduces overall system complexity while maintaining smooth transitions.
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 enhances the spatial resolution and usability of 3D LF displays by reducing diffraction blur, enabling more realistic visual experiences and accommodating user movements, while maintaining cost-effectiveness and ease of calibration.
Implementation Method 1
The main problems with this technology is a lack of suitable Spatial Light Modulator (SLM) component that could be used in the creation of the extremely detailed wavefronts
Implementation Method 2
The implementation of a grating interferometer and Spatial Light Modulator (SLM) structure that enlarges the aperture size
Data Source
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Figure 2A~2B
AI summary
Display methods and apparatus are described. In some embodiments, to generate an image, light is selectively emitted from one or more light-emitting elements (such as a µLEDs) in a light-emitting layer. The emitted light from each element is collimated using, for example, an array of microlenses having small apertures. Each beam of collimated light is split by a first diffractive grating into a first generation of child beams, and the first generation of child beams is split by a second diffractive grating into a second generation of child beams. Beams in the second generation of child beams that are not parallel to the original beam of collimated light may be blocked by a spatial light modulator (e.g. an LCD panel). The un-blocked beams operate in some respects as if they had been generated using optics with an aperture larger than the apertures of the microlenses.