High-Index Eyepiece Waveguide Architecture for Wide-FOV AR
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Solution Overview
Problem
Challenges exist in producing augmented reality technology that provides a comfortable, natural-feeling presentation of virtual image elements amidst real-world imagery, particularly due to complexities in human visual perception systems.
Innovation Solution
A head-mounted display system utilizing waveguides made of materials with a refractive index greater than glass (e.g., Lithium Niobate or silicon carbide) to direct light into the user's eye, enabling the projection of augmented reality image content with enhanced field of view and reduced complexity by using a single waveguide to propagate multiple colors through total internal reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If traditional glass waveguides are used to display augmented reality content, then the device structure is simpler to manufacture, but the field of view is narrower and the device thickness is greater
Solution Approach 1:
The patent changes the refractive index parameter of the waveguide material from traditional glass (n<1.79) to high index materials like lithium niobate (n>2.2). This parameter change enables wider field of view, reduced device thickness, and the ability to guide multiple wavelengths concurrently, directly resolving the technical contradiction between field of view and material complexity.
2Adaptability or versatility
If multiple waveguides are used to propagate different colors, then color guidance is achieved, but the device complexity and thickness increase
Solution Approach 1:
The patent makes a single high index waveguide perform multiple functions by enabling it to guide multiple wavelengths (colors) of light concurrently through total internal reflection. This universal waveguide replaces what would traditionally require multiple separate waveguides, thereby reducing device complexity and thickness while maintaining full color guidance capability.
3Area of stationary object
If high refractive index materials are used, then the field of view and multi-color guidance are improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent accepts the trade-off of increased manufacturing precision requirements as necessary to achieve the significant improvements in field of view and multi-color guidance. The use of high index materials like lithium niobate requires more precise fabrication to control total internal reflection, but this precision investment enables the desired optical performance enhancements.
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 system achieves a wider field of view, reduced thickness, and lower complexity in displaying augmented reality content by employing high refractive index waveguides, allowing for concurrent guidance and out-coupling of multiple colors, thereby improving the user experience.
Implementation Method 1
employing high refractive index waveguides, allowing for concurrent guidance and out-coupling of multiple colors
Implementation Method 2
a waveguide configured to receive the multiplexed light stream emitted from the image projection device such that the first light stream, the second light stream and the third light stream are guided within the waveguide by multiple total internal reflections
Data Source
AI summary
Very high refractive index (n>2.2) lightguide substrates enable the production of 70° field of view eyepieces with all three color primaries in a single eyepiece layer. Disclosed herein are viewing optics assembly architectures that make use of such eyepieces to reduce size and cost, simplifying manufacturing and assembly, and better-accommodating novel microdisplay designs.