Waveguide Exit Pupil Expander Uniform Intensity
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Solution Overview
Problem
Current augmented reality display systems using optical waveguides face challenges in achieving uniform intensity distribution and efficient pupil expansion, leading to non-uniform image reproduction and noticeable artifacts.
Innovation Solution
The apparatus includes an optical waveguide with an input-coupler, one or more intermediate-components, and an output-coupler, where the input-coupler diffracts light in multiple directions, and the intermediate-components perform both odd-order and even-order pupil expansion through total internal reflection, ensuring light is diffracted towards the output-coupler for uniform intensity distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the input-coupler diffracts light in only one direction towards a single intermediate-component that performs only one type of pupil expansion, then the device complexity is reduced, but the intensity distribution becomes non-uniform and artifacts are noticeable
Solution Approach 1:
The input-coupler is segmented into multiple diffraction regions that direct light to different intermediate-components, each performing specific pupil expansion operations. This segmentation allows the system to achieve uniform intensity distribution by distributing light through multiple independent optical paths, resolving the contradiction between simplified structure and uniform intensity output.
Solution Approach 2:
The patent implements nested pupil expansion where intermediate-components perform sequential odd-order and even-order expansions. The first intermediate-component performs odd-order expansion, and the second performs even-order expansion, with each nested within the optical path of the previous. This nested structure achieves comprehensive pupil expansion and uniform intensity distribution while maintaining manageable device complexity.
2Manufacturing precision
If multiple intermediate-components are used to perform both odd-order and even-order pupil expansion, then the intensity distribution uniformity is improved, but the device complexity increases
Solution Approach 1:
Each intermediate-component is designed with multi-functionality, performing both pupil expansion and light redirection functions. The components are configured to handle specific diffraction orders while also directing light appropriately within the waveguide. This multi-functionality reduces the need for additional specialized components, thereby limiting the increase in device complexity while achieving uniform intensity distribution.
Solution Approach 2:
The patent addresses pupil expansion in multiple dimensional aspects by separating odd-order and even-order expansions into different intermediate-components. This dimensional separation in the optical path allows each component to specialize in specific expansion operations, achieving comprehensive uniformity without requiring an excessive number of components.
3Adaptability or versatility
If light travels different path lengths through odd-order and even-order pupil expansion, then the pupil expansion effectiveness is improved, but the device complexity increases
Solution Approach 1:
Different regions of the optical path are assigned different functions: odd-order pupil expansion in one region, even-order expansion in another. Each intermediate-component is positioned and configured with local quality optimized for its specific function. This localized optimization achieves effective pupil expansion while keeping the overall optical path configuration manageable through clear functional zonation.
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 achieves a more uniform intensity distribution and improved image reproduction by ensuring light is diffracted uniformly across the output-pupil, reducing non-uniformities and artifacts, thereby enhancing the visual experience in augmented reality displays.
Implementation Method 1
The input-coupler couples light corresponding to the image and associated with the input-pupil into the optical waveguide and diffracts the light corresponding to the image in at least two different directions
Implementation Method 2
The intermediate-component(s) is/are configured to individually or collectively perform both odd-order pupil expansion and even-order pupil expansion on light corresponding to the image that travels from the input-coupler to the one or more intermediate-components by way of TIR
Implementation Method 3
The output-coupler is configured to couple the light corresponding to the image, that has travelled from the one or more intermediate-components to the output-coupler by way of TIR, out of the optical waveguide
Data Source
Figure 1A~1C
Figure 2
Figure 3~4
AI summary
An apparatus for use in replicating an image associated with an input-pupil to an output-pupil, comprises an optical waveguide including input-coupler, one or more intermediate-components and an output-coupler. The input-coupler couples light corresponding to the image into the optical waveguide and diffracts the light corresponding to the image in at least two different directions so that light corresponding to the image is diffracted toward each of the one or more intermediate-components. The intermediate-component(s) is/are configured to individually or collectively perform both odd-order pupil expansion and even-order pupil expansion on light corresponding to the image that travels from the input-coupler to the one or more intermediate-components by way of TIR, and diffract the light corresponding to the image towards the output-coupler. The output-coupler is configured to couple the light corresponding to the image out of the optical waveguide so that the light corresponding to the image is viewable from the output-pupil.