Multimaterial Metasurface Waveguides for Accommodative-Vergence Alignment
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Solution Overview
Problem
Conventional augmented and virtual reality display systems struggle to provide a comfortable and realistic presentation of virtual image elements amidst real-world imagery due to mismatches between accommodative and vergence states, leading to user discomfort.
Innovation Solution
The use of metasurfaces with multiple materials and structured protrusions on waveguides to redirect light, allowing for precise control of wavefront divergence and alignment with physiological accommodative and vergence cues, enhancing the perception of depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional display systems present virtual image information without transparency to real-world visual input, then virtual reality experience is achieved, but user comfort deteriorates due to mismatch between accommodative and vergence states
Solution Approach 1:
The patent applies local quality by creating spatially varying optical properties across the waveguide surface through metasurface structures. Different regions of the waveguide have different light-redirecting characteristics, enabling localized control of wavefront divergence to match physiological accommodative cues at specific viewing locations while maintaining overall VR/AR functionality
Solution Approach 2:
The patent changes optical parameters by using metasurface protrusions with varying geometries, materials, and configurations to dynamically adjust wavefront divergence. The multiple materials with different refractive indices and the varied protrusion structures enable continuous parameter adjustment to align accommodative and vergence states, resolving the comfort issue
2Ease of operation
If metasurfaces with multiple materials and structured protrusions are used to redirect light, then depth perception and user comfort are improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the metasurface into multiple discrete protrusion elements arranged in specific patterns. Each protrusion can have different materials, heights, and geometries, allowing independent optimization of light-redirecting properties while maintaining manufacturability through standardized fabrication processes
Solution Approach 2:
The patent uses composite materials by combining multiple materials with different refractive indices within the metasurface structure. This enables precise control of light propagation and wavefront divergence to achieve improved depth perception, while the composite nature allows tuning of optical properties without requiring completely new material discoveries
3Ease of manufacture
If conventional single-material structures are used in waveguides, then manufacturing is simpler, but light redirection precision and wavefront control are insufficient
Solution Approach 1:
The patent applies preliminary action by pre-configuring the metasurface protrusions with specific geometries and material compositions during the waveguide fabrication process. The protrusions are formed with predetermined characteristics that enable precise light redirection, and the fabrication methods (such as deposition and etching) are designed to achieve the required precision in a single manufacturing flow
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 improved depth perception and comfort by aligning accommodative and vergence states, resulting in a more realistic and immersive augmented and virtual reality experience.
Implementation Method 1
The optical element is configured to redirect light having a wavelength, and comprises a plurality of spaced-apart protrusions disposed on the waveguide. Each protrusion comprises a first vertical layer comprising a first material, and a second vertical layer comprising a second material different from the first material.
Implementation Method 2
The optical element may be a metasurface. The plurality of protrusions may comprise at least one of nanobeams and pillars. Protrusions of the plurality of protrusions may be separated from each other by a sub-wavelength spacing.
Data Source
AI summary
Display devices include waveguides with metasurfaces as in-coupling and/or out-coupling optical elements. The metasurfaces may be formed on a surface of the waveguide and may include a plurality or an array of sub-wavelength-scale (e.g., nanometer-scale) protrusions. Individual protrusions may include horizontal and/or vertical layers of different materials which may have different refractive indices, allowing for enhanced manipulation of light redirecting properties of the metasurface. Some configurations and combinations of materials may advantageously allow for broadband metasurfaces. Manufacturing methods described herein provide for vertical and/or horizontal layers of different materials in a desired configuration or profile.