Waveguide Diffraction Structure for Multi-Focal 3D Displays
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Solution Overview
Problem
Conventional 3D displays in virtual and augmented reality systems often cause eye strain and discomfort due to mismatched accommodative responses, leading to unstable imaging and a lack of perceived surface depth.
Innovation Solution
Implementing a diffraction structure with a waveguide substrate, underlayer, and top grating surface, each with distinct refractive indices, to enhance diffraction efficiency and counteract angle-dependent reductions, combined with precise deposition techniques for imprint materials to create uniform and variable thicknesses, allowing for multiple focal planes and improved depth perception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional 3D displays are used in virtual and augmented reality systems, then the system structure is simple, but eye strain and discomfort occur due to mismatched accommodative responses
Solution Approach 1:
The display system is segmented into multiple focal planes, with each plane presenting content at a different focal distance. This allows the accommodative response to match the vergence response, eliminating the vergence-accommodation conflict that causes eye strain in conventional 3D displays.
Solution Approach 2:
The patent introduces a new dimension of focal depth by presenting content at multiple focal distances along the optical axis. This transforms the traditional 2D display into a multi-planar 3D display, enabling the eyes to focus at different depths while maintaining proper accommodative-vergence coupling.
2Ease of manufacture
If conventional diffraction structures are used, then manufacturing is simpler, but diffraction efficiency decreases at larger angles
Solution Approach 1:
The patent modifies the diffraction grating parameters, specifically the groove depth and spacing, to optimize diffraction efficiency across a wider angular range. By adjusting these parameters, the system maintains high diffraction efficiency even at larger viewing angles while remaining manufacturable.
Solution Approach 2:
The diffraction structure uses a composite design combining multiple grating layers with different orientations and depths. This composite structure enhances diffraction efficiency across various angles by distributing the diffraction function across multiple layers, each optimized for specific angular ranges.
3Ease of manufacture
If uniform thickness deposition is used, then manufacturing is easier, but multiple focal planes and depth perception cannot be achieved
Solution Approach 1:
The patent implements local quality variation in the diffraction grating structure, where different regions have different groove depths and patterns. This allows each region to contribute to a specific focal plane, enabling precise control over multiple focal distances while using standard deposition processes.
Solution Approach 2:
The system dynamically controls the effective focal planes by varying the diffraction grating parameters across different spatial locations. This dynamic approach allows the same manufacturing process to produce a structure with multiple functional focal planes, each optimized for specific depth perception requirements.
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
The solution provides a larger field of view and increased diffraction efficiency, reducing eye strain and enhancing the perception of depth by aligning accommodative responses with virtual depth cues, resulting in a more comfortable and natural 3D display experience.
Implementation Method 1
a diffractive optical element (DOE) to receive the light associated with the one or more frames of image data and direct the light to the user's eyes
Implementation Method 2
a waveguide substrate corresponding to a waveguide refractive index
Data Source
AI summary
Disclosed is an improved diffraction structure for 3D display systems. The improved diffraction structure includes an intermediate layer that resides between a waveguide substrate and a top grating surface. The top grating surface comprises a first material that corresponds to a first refractive index value, the underlayer comprises a second material that corresponds to a second refractive index value, and the substrate comprises a third material that corresponds to a third refractive index value. According to additional embodiments, improved approaches are provided to implement deposition of imprint materials onto a substrate, which allow for very precise distribution and deposition of different imprint patterns onto any number of substrate surfaces.