Diffractive Waveguide Coupling-In Grating for Uniform AR Brightness
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Solution Overview
Problem
The design of the coupling-in grating in conventional diffractive optical waveguides results in poor efficiency and non-uniformity, leading to non-uniform image brightness in the field of view, affecting user experience in AR glasses.
Innovation Solution
A diffractive optical waveguide with a coupling-in grating comprising randomly arranged grating blocks of the same period but different duty cycles, and optionally varying depths and tilt angles, optimized using an optimization algorithm to enhance diffraction efficiency and non-uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional coupling-in grating design with uniform duty cycle is used, then manufacturing is simple, but diffraction efficiency and image brightness uniformity are poor
Solution Approach 1:
The patent applies local quality by dividing the coupling-in grating into multiple grating blocks with different duty cycles. Each grating block has a locally optimized duty cycle value that varies across different regions of the grating, allowing different areas to handle light at different angles optimally, thereby improving overall diffraction efficiency and brightness uniformity while managing structural complexity through systematic local variation.
Solution Approach 2:
The patent implements parameter changes by systematically varying the duty cycle parameter across different grating blocks. The duty cycle is changed from a uniform value to a gradient distribution where adjacent grating blocks have different duty cycle values, directly addressing the diffraction efficiency problem while maintaining a structured approach to complexity management.
2Illumination intensity
If coupling-in grating with different duty cycles is used, then image brightness uniformity improves, but manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by assigning different duty cycle values to different grating blocks based on their positional requirements for brightness uniformity. This localized optimization ensures that each region contributes appropriately to overall image brightness while the systematic gradient approach keeps manufacturing complexity manageable through predictable patterns.
Solution Approach 2:
The patent segments the coupling-in grating into multiple discrete grating blocks, each with independently optimized duty cycle values. This segmentation allows for localized duty cycle variation to improve brightness uniformity while enabling modular manufacturing approaches that can reduce overall fabrication complexity through standardized block production.
3Productivity
If grating blocks with varying duty cycles are implemented, then diffraction efficiency improves, but design and fabrication complexity increases
Solution Approach 1:
The patent systematically changes the duty cycle parameter across grating blocks to optimize diffraction efficiency. By implementing a gradient distribution where duty cycles vary in a controlled manner across adjacent blocks, the patent achieves improved diffraction efficiency while managing design complexity through a structured parameter variation approach rather than arbitrary changes.
Solution Approach 2:
The patent applies local quality by optimizing the duty cycle of each grating block according to its specific position and function within the overall grating structure. This localized optimization improves diffraction efficiency for light at different angles while maintaining design manageability through systematic local variations rather than unstructured complexity.
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
Improves diffraction efficiency and non-uniformity, reducing uneven image brightness and enhancing user experience by optimizing the coupling-in grating design.
Implementation Method 1
The coupling-in grating is disposed on or in the waveguide substrate and located in the coupling-in region, and is configured to couple input light into the waveguide substrate to cause the input light to propagate within the waveguide substrate through total reflection
Data Source
AI summary
A diffractive optical waveguide, a design method for the diffractive optical waveguide, and a display device are provided. The diffractive optical waveguide includes a waveguide substrate and a coupling-in grating. The coupling-in grating includes a plurality of coupling-in grating blocks arranged randomly and continuously, the plurality of coupling-in grating blocks have the same period, and at least two coupling-in grating blocks of the plurality of coupling-in grating blocks have different duty cycles; a first coupling-in grating block of the at least two coupling-in grating blocks includes a plurality of grating units, and each grating unit has a first duty cycle; a second coupling-in grating block of the at least two coupling-in grating blocks includes a plurality of grating units, and each grating unit has a second duty cycle; the first duty cycle is different from the second duty cycle.