Zoned Diffractive Light Guide for Uniform Eyebox Output
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Solution Overview
Problem
Conventional image light guides in head-mounted displays suffer from limitations in diffraction efficiency, image-bearing light output intensity, and uniformity across the entire output aperture, which affect the quality of virtual image presentation.
Innovation Solution
The implementation of a zoned out-coupling diffractive optic with varying diffractive features and zones in the image light guide, designed to enhance diffraction efficiency and uniformity by strategically redirecting image-bearing light for expanded eyebox coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional out-coupling diffractive optic is used, then the device structure is simple, but the diffraction efficiency is insufficient and uniformity across the output aperture is poor
Solution Approach 1:
The out-coupling diffractive optic is divided into multiple zones (first zone, second zone, third zone) with different diffractive feature configurations. Each zone independently directs light to specific regions of the eyebox, enabling optimized diffraction efficiency for different viewing angles and positions without requiring a completely different optical structure.
Solution Approach 2:
Different regions of the diffractive optic are assigned different properties: the first zone has features optimized for central eyebox regions, the second zone for intermediate regions, and the third zone for peripheral regions. This local optimization ensures high diffraction efficiency and uniformity across the entire output aperture while maintaining a single integrated optic structure.
2Manufacturing precision
If a single-zone diffractive optic is used, then the manufacturing process is simple, but the uniformity of image-bearing light output across the entire output aperture is insufficient
Solution Approach 1:
The diffractive optic is segmented into multiple zones with progressively different diffractive feature parameters. The first zone directs light to the central eyebox region, the second zone to intermediate regions, and the third zone to peripheral regions. This segmentation enables uniform light distribution across the entire output aperture while using standard manufacturing processes for creating the zoned 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
The zoned out-coupling diffractive optic improves diffraction efficiency and uniformity of image-bearing light output, providing a more consistent and high-quality virtual image presentation across the entire output aperture.
Implementation Method 1
an out-coupling diffractive optic operable to direct the image-bearing light beams from the waveguide toward an eyebox. The out-coupling diffractive optic having a first zone located adjacent to a second zone, wherein the first zone includes a first set of diffractive features and said second zone includes a second set of diffractive features
Data Source
AI summary
An image light guide for conveying a virtual image, including a waveguide, an in-coupling diffractive optic operable to direct image-bearing light beams into the waveguide, and an out-coupling diffractive optic operable to direct the image-bearing light beams from the waveguide toward an eyebox. The out-coupling diffractive optic having two or more zones each including a set of diffractive features, wherein a first zone includes a first set of diffractive features and a second zone includes a second set of diffractive features and is located adjacent to the first zone. The out-coupling diffractive optic includes a first interface region formed by the first zone and the second zone, and the first interface region includes a first set of sub-regions and a second set of sub-regions. The first set of sub-regions includes the first set of diffractive features, and the second set of sub-regions includes the second set of diffractive features.