Parallelogram Grating Asymmetric Diffraction for Compact AR Waveguides
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Solution Overview
Problem
Existing optical waveguides, particularly those based on two-dimensional gratings and one-dimensional gratings, face limitations such as restricted application due to pupil expansion methods and bulky head-mounted display systems, which hinder the development of large-field-of-view AR devices suitable for consumer markets.
Innovation Solution
The proposed optical waveguide system incorporates a grating with a plurality of cell arrays having a parallelogram shape, allowing incident light to be diffracted into two beams with unequal angles, enabling a more flexible and compact design for augmented reality devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two-dimensional gratings with equal diffraction angles are used, then the optical waveguide can be designed, but the pupil expansion method limits the application and increases device complexity
Solution Approach 1:
The patent employs asymmetric diffraction angle design where the first diffraction angle differs from the second diffraction angle. This asymmetry breaks the conventional symmetric pupil expansion method, enabling more flexible optical path design and reducing system complexity while maintaining waveguide functionality.
Solution Approach 2:
The patent transitions from conventional two-dimensional grating patterns to three-dimensional structured gratings with varying heights. This dimensional enhancement enables independent control of diffraction angles in different spatial directions, providing additional design freedom to resolve the contradiction between application flexibility and system complexity.
2Ease of manufacture
If one-dimensional gratings are used, then the optical waveguide can be constructed, but the areas or volumes become relatively large resulting in bulky head-mounted display systems
Solution Approach 1:
The patent introduces height variation as a third dimension in grating structure, transforming conventional two-dimensional gratings into three-dimensional structured gratings. This enables more compact optical path folding and reduces the overall volume of the head-mounted display while maintaining manufacturability.
Solution Approach 2:
The patent utilizes parameter changes in grating structure, specifically varying the heights of different grating regions, to control light diffraction patterns. This parameter optimization enables miniaturization of the optical waveguide components while preserving ease of manufacture through standardized fabrication processes.
3Device complexity
If conventional symmetric diffraction is used, then the optical system is simple to design, but the light efficiency is limited and design flexibility is reduced
Solution Approach 1:
The patent implements asymmetric diffraction angle design where different diffraction angles are used for different optical paths. This asymmetry optimizes light distribution and efficiency while maintaining manageable design complexity through systematic structural arrangements.
Solution Approach 2:
The patent applies local quality variations by assigning different heights to different grating regions. This enables localized optimization of light diffraction efficiency in specific areas of the waveguide while keeping the overall design systematic and manageable.
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 solution enhances light efficiency, reduces the volume of the waveguide lens, and allows for greater design flexibility, making it more suitable for consumer-scale augmented reality applications.
Implementation Method 1
one incident light beam incident on the grating is diffracted into two diffracted light beams
Data Source
AI summary
An optical waveguide system and an augmented reality device are disclosed. The optical waveguide system comprises an optical waveguide and a grating disposed on a surface of the optical waveguide, the grating comprises a plurality of cell arrays each having a parallelogram shape, such that one incident light beam incident on the grating is diffracted into two diffracted light beams, and angle between components of one diffracted light beam and the other diffracted light beam on a plane of the grating and a component of the incident light beam on the plane of the grating are not equal. The optical waveguide system including the grating can be combined in more flexible forms, for improving the lighting efficiency, reducing and maintaining a smaller volume of the waveguide lens etc., and the appearance of the waveguide system can also be changed more freely, to meet the preferences of different consumers.