Apparatus for providing waveguide displays with two-dimensional pupil expansion
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Solution Overview
Problem
Existing waveguide displays require multiple layers for dual axis beam expansion, leading to increased thickness, weight, and haze, which is unacceptably high for practical applications like augmented reality and sensor systems.
Innovation Solution
A compact dual axis expansion waveguide using a first waveguide with an input coupler, fold grating, and output grating, where at least one of the gratings is a rolled k-vector grating, allowing for dual pupil expansion in orthogonal directions without the need for multiple layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple layers are used for dual axis beam expansion, then beam expansion capability is improved, but thickness and weight increase
Solution Approach 1:
The patent combines multiple grating functions into a single integrated waveguide layer. The input coupler grating, fold grating, and output grating are all implemented within one waveguide substrate, eliminating the need for multiple separate layers while maintaining dual axis beam expansion capability.
Solution Approach 2:
The patent uses a folded light path configuration where light undergoes multiple reflections within the waveguide layer. By utilizing the third dimension (vertical reflections) within a single layer, the system achieves dual axis expansion without increasing the horizontal footprint or requiring multiple stacked layers.
2Adaptability or versatility
If multiple layers are used for dual axis beam expansion, then beam expansion capability is improved, but weight increases
Solution Approach 1:
The patent combines multiple grating functions into a single integrated waveguide layer. The input coupler grating, fold grating, and output grating are all implemented within one waveguide substrate, eliminating the need for multiple separate layers while maintaining dual axis beam expansion capability.
3Adaptability or versatility
If multiple layers are used for dual axis beam expansion, then beam expansion capability is improved, but haze increases
Solution Approach 1:
The patent combines multiple grating functions into a single integrated waveguide layer. The input coupler grating, fold grating, and output grating are all implemented within one waveguide substrate, eliminating the need for multiple separate layers while maintaining dual axis beam expansion capability.
4Length of stationary object
If a compact single layer waveguide is used, then thickness and weight are reduced, but dual axis expansion capability may be compromised
Solution Approach 1:
The patent uses a folded light path configuration where light undergoes multiple reflections within the waveguide layer. By utilizing the third dimension (vertical reflections) within a single layer, the system achieves dual axis expansion without increasing the horizontal footprint or requiring multiple stacked layers.
Solution Approach 2:
The patent employs a folded grating design that dynamically redirects light at 45-degree angles through total internal reflection. This dynamic light routing enables the single layer to perform multiple optical functions including beam expansion in both horizontal and vertical directions.
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 low-cost, efficient, and compact dual axis expansion, reducing thickness and weight while maintaining high transparency, suitable for near-eye displays and sensor applications.
Implementation Method 1
The input coupler is configured to receive collimated first wavelength light from an Input Image Node (IIN) and to cause the light to travel within the first waveguide via total internal reflection between the first surface and the second surface
Implementation Method 2
The fold grating is configured to provide pupil expansion in a first direction and to direct the light to the output grating via total internal reflection between the first surface and the second surface
Implementation Method 3
The output grating is configured to provide pupil expansion in a second direction different than the first direction and to cause the light to exit the first waveguide
Data Source
AI summary
An optical display comprises: a first waveguide comprising a first surface and a second surface, an input coupler, a fold grating, and an output grating. The input coupler receives collimated first wavelength light from an Input Image Node causes the light to travel within the first waveguide via total internal reflection between the first surface and the second surface to the fold grating. The fold grating provides pupil expansion in a first direction directs the light to the output grating via total internal reflection between the first surface and the second surface. The output grating provides pupil expansion in a second direction different than the first direction and causes the light to exit the first waveguide from the first surface or the second surface. At least one of the input coupler, fold grating and output grating is a rolled k-vector grating, and the fold grating is a dual interaction grating.