Non-Parallel Waveguide Assemblies for AR Image Quality
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Solution Overview
Problem
In near-eye display devices, the spatial translation of images using optical waveguides often results in image degradation due to physical space and shape constraints, particularly in mirror configurations where multiple waveguides are employed, leading to misalignment and interference fringes that affect image quality.
Innovation Solution
The use of tunable waveguide assemblies with non-parallel waveguides and diffractive optical elements, where input and output couplers are adjusted to align light paths and compensate for airgap wedges, ensuring that light from different waveguides is emitted at the same angles to reduce misalignment and interference fringes, thereby enhancing image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If multiple waveguides are employed in mirror configuration to meet spatial constraints, then the device can be compact and fit NED form factors, but image degradation occurs due to misalignment and interference fringes
Solution Approach 1:
The patent applies asymmetry by using non-parallel waveguides instead of traditional parallel waveguides in mirror configuration. The waveguides are angled relative to each other, which eliminates interference fringes caused by parallel surfaces while maintaining the compact mirror configuration architecture suitable for NED devices.
Solution Approach 2:
The patent changes the geometric parameter of waveguide arrangement from parallel to non-parallel (angled) configuration. This parameter change modifies the optical path relationships to eliminate interference fringes while maintaining device compactness. The coupling elements are also tuned to specific parameters to compensate for airgap wedges and achieve proper light path alignment.
2Ease of manufacture
If traditional parallel waveguides are used in mirror configuration, then alignment is simpler, but interference fringes are generated that degrade image quality
Solution Approach 1:
The patent deliberately introduces asymmetry by using non-parallel waveguides at specific angles. This asymmetric configuration eliminates the interference fringes that occur with parallel waveguides, trading the simplicity of parallel alignment for superior image quality without significantly complicating the manufacturing process.
3Manufacturing precision
If waveguides are tuned to compensate for airgap wedges, then light paths are properly aligned and interference fringes are reduced, but the device complexity increases
Solution Approach 1:
The patent adjusts the parameters of coupling elements (such as grating periods, orientations, and positions) to compensate for airgap wedges between non-parallel waveguides. These parameter adjustments enable proper light path alignment and fringe reduction. The complexity is managed by integrating these tuned coupling elements directly into the waveguide structure, making the tuning part of the manufacturing process rather than a separate adjustment step.
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 improves image quality by mitigating image degradation caused by misalignment and interference fringes, resulting in higher quality images being transmitted to the user's eyes while maintaining the architectural advantages of mirror configurations.
Implementation Method 1
diffractive optical elements, where input and output couplers are adjusted to align light paths
Implementation Method 2
an optical waveguide made of a substrate can spatially translate propagating light waves representing imagery generated by a light engine and convey them along an optical path
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
The description relate to devices, such as augmented reality and/or virtual reality devices that employ optical waveguides. On example includes a first optical waveguide configured to receive light at an incidence angle and a second optical waveguide positioned in a non-parallel relation to the first optical waveguide. The second optical waveguide can be configured to receive the light through the first optical waveguide at a first location at the incidence angle, transmit the light within the second optical waveguide, and output the light from a second location back toward the first optical waveguide at the incidence angle.