Multi-Layered Optical Gratings for AR Waveguide Coupling
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Solution Overview
Problem
Augmented reality (AR) and mixed reality (XR) eyewear displays using waveguides often suffer from limited resolution, contrast, display uniformity, input coupling efficiency, and output coupling efficiency.
Innovation Solution
Implementing multi-layered optical gratings with varying depths, slope angles, and geometries in a repeating arrangement on the waveguide to optimize optical characteristics, such as high resolution and contrast, and improve coupling efficiencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional optical gratings are used in waveguides, then the structure is simple and manufacturing is easier, but the resolution, contrast, and coupling efficiency are limited
Solution Approach 1:
The optical grating is segmented into multiple layers, each layer contributing to the overall optical coupling function. This multi-layer segmentation allows for optimized light coupling at different depths and angles, significantly improving coupling efficiency while distributing the structural complexity across manageable layers
Solution Approach 2:
The patent transitions from conventional two-dimensional grating structures to three-dimensional multi-layered gratings with varying depths and slope angles. This dimensional enhancement enables precise control of light coupling in multiple spatial dimensions, achieving superior coupling efficiency and optical performance
2Illumination intensity
If higher power is used in conventional AR displays, then display quality improves, but power consumption increases
Solution Approach 1:
The patent replaces the conventional approach of increasing light source power with an optical structure-based solution. The multi-layered gratings with optimized geometries passively enhance light coupling and directional control, achieving improved display quality through optical design rather than increased power consumption
Solution Approach 2:
The patent optimizes multiple geometric parameters of the gratings including depth, slope angle, and layer spacing. These parameter optimizations maximize light coupling efficiency and directional control, enabling high display quality with lower power input by improving the optical system's efficiency
3Illumination intensity
If light is directed more towards the user's eye, then display quality improves, but 'eye glow' is reduced
Solution Approach 1:
The multi-layered gratings create localized optical control at different depths and positions within the waveguide. Each layer is optimized to direct light specifically toward the user's eye at particular locations, enhancing display quality in the desired viewing zone while minimizing stray light and eye glow in other 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
Enables lower-power AR eyewear displays to produce display quality comparable to higher-power conventional AR eyewear displays by enhancing optical characteristics and reducing 'eye glow' by directing more light towards the user's eye.
Implementation Method 1
light from an image source is coupled into a light guide substrate, generally referred to as a waveguide, by an input optical coupling such as an in-coupling grating
Implementation Method 2
Once the light has been coupled into the waveguide, the incoupled light is 'guided' through the substrate, typically by multiple instances of total internal reflection
Data Source
AI summary
An augmented-reality (AR) eyewear display utilizes an optical waveguide having multi-layered optical gratings in a repeating arrangement. The optical gratings include varying depths, slope angles, lengths, and/or widths in order to tune the gratings to provide an improved AR eyewear display. By using the different configurations of two-dimensional or three-dimensional gratings disclosed herein in a waveguide of an AR eyewear display, optical characteristics of the waveguide are optimized to provide, e.g., high resolution and/or contrast, high display uniformity, high input coupling efficiency, and/or high output coupling efficiency. Accordingly, in some embodiments, aspects of the present disclosure enable lower-power AR eyewear displays to produce the same quality of display of a higher-power conventional AR eyewear display waveguide.