Waveguide Combiner With Switchable Multi-Plane Image Projection
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Solution Overview
Problem
Conventional waveguide combiners in mixed reality systems face limitations in dynamically projecting images at different distances, leading to aberrations and fixed image locations, which hinder the perception of depth and flexibility in displaying content.
Innovation Solution
Employing a waveguide combiner with multiple switchable diffraction gratings, each characterized by distinct focal distances, and controlled by a controller to project images at different image planes through time-based or wavelength-based synchronization, allowing dynamic image projection and depth perception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional waveguide combiner uses a fixed diffraction grating, then the image location is fixed and the structure is simple, but the system cannot dynamically project images at different distances and exhibits aberrations
Solution Approach 1:
The patent applies dynamics by replacing the fixed diffraction grating with multiple switchable diffraction gratings that can be selectively activated. Each diffraction grating is designed with a different focal distance, allowing the system to dynamically project images at varying distances by switching between gratings based on the desired image plane, thereby resolving the contradiction between adaptability and structural simplicity.
Solution Approach 2:
The patent segments the single diffraction grating into multiple distinct diffraction gratings, each optimized for a specific focal distance. This segmentation allows the system to handle different image projection requirements independently, improving adaptability while maintaining manageable structural complexity through modular design.
2Adaptability or versatility
If multiple diffraction gratings with different focal distances are used, then images can be projected at different image planes, but the device complexity increases
Solution Approach 1:
The patent merges multiple diffraction gratings into a single integrated waveguide combiner structure. By combining the gratings within one device and using a controller to manage their activation, the system achieves multiple image plane capability while consolidating the overall structure, thus balancing adaptability with device complexity.
Solution Approach 2:
The waveguide combiner is designed as a universal device that can project images at multiple different image planes using a single structure. The controller enables the combiner to perform multiple functions (projecting at different distances) without requiring separate devices for each function, thereby improving adaptability while avoiding proportional increases in complexity.
3Adaptability or versatility
If dynamic grating switching is implemented, then depth perception is enhanced, but the control system becomes more complex
Solution Approach 1:
The controller is designed to automatically manage the activation of diffraction gratings based on the desired image plane. By implementing self-service control logic that maps image plane selections to specific grating activations, the system enhances depth perception capability while minimizing the complexity of the control system through automated decision-making rather than manual configuration.
4Adaptability or versatility
If multiple diffraction gratings are activated simultaneously, then multiple images can be displayed, but power consumption and luminance requirements increase
Solution Approach 1:
The patent employs periodic action by sequentially activating diffraction gratings rather than simultaneously powering all of them. The controller switches between gratings in a time-multiplexed manner, allowing multiple images to be displayed over time while ensuring that only one grating is active at any given moment, thereby maintaining multi-image display capability while minimizing power consumption and luminance 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
Enables flexible and efficient projection of images at varying distances within the waveguide combiner, enhancing depth perception and reducing aberrations, while maintaining a large eyebox and field of view without increasing power consumption or luminance requirements.
Implementation Method 1
a second optical element that is coupled to an output surface of the substrate and that outputs, from the waveguide combiner, the light propagated along the propagation path. The second optical element can be an out-coupling HOE that includes multiple diffraction gratings disposed in a stacked arrangement. Each of these diffraction gratings is characterized by a focal distance that is different from focal distances of the other diffraction gratings.
Data Source
AI summary
Waveguide combiners with multiple image planes are described herein. In an example, an apparatus includes a first optical element configured to receive light, a substrate having an input surface and an output surface and configured to propagate the light received by the first optical element along a propagation path within the substrate, and a second optical element configured to output the light propagated along the propagation path. The input surface of the substrate is coupled to the first optical element. The second optical element includes a first diffraction grating coupled to the output surface and characterized by a first focal distance and a second diffraction grating coupled to the first diffraction grating in a stacked arrangement and characterized by a second focal distance.