Segmented DOE Waveguide for Uniform AR Near-Eye Brightness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current augmented reality systems face issues with image quality due to local defects in waveguide surfaces, leading to image blur and uneven brightness, and inefficiencies in light output, which are exacerbated by the use of continuous DOEs and thick waveguides.
Innovation Solution
A waveguide structure with segmented diffractive optical elements (DOEs) that include expanding and output-coupling segments, allowing for flexible control of diffraction efficiency, segment density, and alignment to optimize light distribution and reduce light loss, ensuring uniform image brightness and a wide eye motion box.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If continuous (non-segmented) DOEs are used in waveguides, then the manufacturing process is simpler, but the waveguide requires a large area and produces uneven brightness and light loss
Solution Approach 1:
The patent divides the continuous DOE into multiple segmented DOEs arranged in an array. Each segment is a separate diffractive optical element that can be independently controlled. This segmentation allows the waveguide to maintain a compact area while achieving uniform brightness distribution and reduced light loss through optimized light diffraction from each segment.
2Manufacturing precision
If the waveguide thickness is increased to improve image quality, then surface defects have less impact, but the density of exit pupils decreases and the system thickness increases
Solution Approach 1:
By segmenting the DOE into multiple elements, the patent achieves improved image quality even in thinner waveguides. The segmented structure creates multiple exit pupils that compensate for surface defects, maintaining high image quality without increasing waveguide thickness.
Solution Approach 2:
The patent optimizes parameters such as segment spacing, segment size, and diffraction efficiency to achieve high image quality in thin waveguides. By carefully controlling these parameters, the system maintains exit pupil density and image quality without requiring increased thickness.
3Adaptability or versatility
If DOEs emit light in all directions to cover the field of view, then the field of view is maximized, but a significant part of light does not enter the user's eye and is lost
Solution Approach 1:
The patent applies local quality by making each DOE segment emit light preferentially in directions that will enter the user's eye motion box. The segments are positioned and oriented to direct light into the EMB, creating non-uniform angular distribution that maximizes light utilization while maintaining wide field of view.
Solution Approach 2:
The segmented DOE structure provides angular selectivity where only light within specific angular ranges (that will enter the EMB) is effectively utilized. This creates a feedback mechanism where the waveguide structure itself filters and directs light based on the required viewing geometry, reducing light loss.
4Ease of manufacture
If the output-coupling DOE has constant parameters across its surface, then manufacturing is easier, but the displayed image has uneven brightness
Solution Approach 1:
The output-coupling DOE is divided into multiple segments with different parameters (such as different diffraction efficiencies, periods, or orientations). Each segment is optimized to compensate for the decreasing light intensity with distance from the input-coupling DOE, ensuring uniform brightness across the entire output area.
Solution Approach 2:
Different segments of the output-coupling DOE have locally optimized parameters tailored to their specific positions. Segments farther from the input-coupling DOE have higher diffraction efficiency to compensate for light loss over distance, creating uniform overall brightness while maintaining manufacturing feasibility through modular segment design.
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 enhances image quality and efficiency by minimizing light loss and ensuring uniform brightness across the viewing area, enabling a compact and cost-effective near-eye display apparatus with a wide viewing angle.
Implementation Method 1
The main functions of the DOEs are introduction of light into the waveguide propagation mode due to total inner reflection (TIR)... pupil dilation based on a projection system... and light output from the waveguide
Implementation Method 2
introduction of light into the waveguide propagation mode due to total inner reflection (TIR)
Data Source
AI summary
Provided is a waveguide guiding light to a target area, the waveguide including an input-coupling diffractive optical element (DOE) inputting the light into the waveguide, an expanding DOE expanding the light input into the waveguide through the input-coupling DOE, an output-coupling DOE outputting the light expanded in the waveguide by the expanding DOE to an outside of the waveguide, wherein the expanding DOE includes a plurality of expanding segments, and the output-coupling DOE includes a plurality of output-coupling segments.