Multi-Layer Waveguide Assembly for Smart Glasses
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Solution Overview
Problem
Current waveguide assemblies in smart glasses struggle to efficiently transmit light rays of different viewing angles, leading to uneven transmission periods and pupil density, which affects the uniformity and quality of the combined virtual and real scenes experienced by users.
Innovation Solution
A waveguide assembly with a first and second waveguide layer stacked together, along with a spacing layer having distinct refractive index regions that reduce transverse transmission periods and selectively reflect or pass light rays based on viewing angles, utilizing in-coupling and out-coupling gratings to manage light transmission effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single waveguide layer is used to transmit light rays, then the structure is simple, but the transmission period cannot be adjusted for different viewing angles leading to uneven pupil density
Solution Approach 1:
The waveguide assembly is divided into multiple waveguide layers (first waveguide layer and second waveguide layer) with different optical functions. The first waveguide layer handles specific viewing angles while the second waveguide layer handles other viewing angles, allowing independent optimization of transmission paths for each layer to achieve uniform pupil density across all viewing angles.
Solution Approach 2:
The patent introduces a vertical stacking dimension by placing multiple waveguide layers at different heights along the optical path. This multi-layer vertical arrangement allows light rays of different viewing angles to propagate through different layers simultaneously, enabling independent control of transmission periods for each viewing angle without increasing horizontal complexity.
2Reliability
If multiple waveguide layers are stacked to adjust transmission periods, then uniformity of light transmission is improved, but the device structure becomes more complex
Solution Approach 1:
Multiple waveguide layers are merged into a single integrated waveguide assembly that functions as one unified optical component. The layers are closely spaced and optically coupled, allowing them to work together as a combined system rather than separate components, thereby achieving uniform pupil density without proportionally increasing overall device complexity.
Solution Approach 2:
Each waveguide layer is designed with universal characteristics that allow it to handle multiple wavelengths and viewing angles within its designated range. The layers share common structural features and optical properties, enabling the multi-layer structure to achieve enhanced reliability through functional differentiation rather than through complex specialized designs.
3Adaptability or versatility
If the spacing layer has uniform refractive index, then manufacturing is simple, but it cannot selectively reflect or pass light rays of different viewing angles
Solution Approach 1:
The spacing layer is designed with spatially varying refractive index characteristics, where different regions of the layer have different refractive indices optimized for specific viewing angles. This local differentiation allows the spacing layer to selectively reflect or pass light rays based on their incident angles, achieving adaptability for controlling different viewing angles while maintaining a relatively simple overall layer structure.
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 configuration adjusts transmission periods for light rays of different viewing angles, ensuring uniform pupil density and improved image quality by allowing independent or joint transmission of light rays, enhancing the overall performance of smart glasses in combining virtual and real scenes.
Implementation Method 1
a refractive index of the first region is less than that of the first waveguide layer and that of the second waveguide layer, and a refractive index of the second region is less than that of the first region
Implementation Method 2
the second region is configured to allow a first light ray of a first viewing angle in the light rays to be fully reflected
Implementation Method 3
The in-coupling grating is disposed on a side of the first waveguide layer away from the second waveguide layer, wherein the in-coupling grating corresponds to the first region. The first out-coupling grating is disposed on the side of the first waveguide layer away from the second waveguide layer
Data Source
AI summary
A waveguide assembly, an optical device and smart glasses are provided. The waveguide assembly includes a first waveguide layer, a second waveguide layer, and a first spacing layer. The first spacing layer includes a first region and a second region. A refractive index of the first region is less than that of the first waveguide layer and that of the second waveguide layer. A refractive index of the second region is less than that of the first region.