Diffraction Grating Layout for Faster Near-Eye Waveguide Writing
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Solution Overview
Problem
Conventional methods for producing optical image light guides in virtual image near-eye display systems are time and capital intensive.
Innovation Solution
A method involving a substrate with multiple diffraction gratings, including a first, second, and third diffraction grating, where the gratings are oriented relative to the x- and y-axes of a beam writing machine to reduce writing time, using electron beam or ion beam lithography to create a diffraction grating pattern directly on a mold substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional methods are used to produce optical image light guides, then manufacturing precision can be maintained, but production time and cost increase significantly
Solution Approach 1:
The patent segments the diffraction grating pattern into multiple independent gratings (first, second, and third diffraction gratings) that can be written separately. Each grating is aligned with the beam writing system's preferred writing directions, allowing efficient sequential fabrication without requiring complex repositioning operations.
Solution Approach 2:
The patent employs preliminary alignment of the substrate and diffraction grating layouts before the writing process. The beam writing system is positioned and oriented in advance with respect to the substrate coordinates, and the diffraction grating patterns are pre-configured to match the system's preferred writing directions, eliminating time-consuming adjustments during fabrication.
2Adaptability or versatility
If diffraction gratings are written at arbitrary orientations, then design flexibility is improved, but write time increases due to non-preferred writing directions
Solution Approach 1:
The patent introduces asymmetric orientation relationships between the diffraction grating vectors and the beam writing system axes. By deliberately aligning grating vectors at specific angles (0°, 90°, or other preferred directions) relative to the writing system, the patent optimizes writing efficiency while maintaining sufficient design flexibility for the optical functionality.
Solution Approach 2:
The patent changes the orientation parameters of the diffraction gratings to match the beam writing system's preferred directions. This parameter optimization ensures that all gratings are written along high-efficiency paths, reducing total write time while preserving the essential optical performance through appropriate grating vector configurations.
3Adaptability or versatility
If multiple diffraction gratings are fabricated on a single substrate, then device functionality is improved, but fabrication complexity increases
Solution Approach 1:
The patent merges multiple diffraction grating fabrication processes into a single unified workflow. Multiple gratings with different orientations and functions are fabricated on one substrate using the same beam writing system and coating material, simplifying the overall fabrication process while achieving complex optical functionality.
Solution Approach 2:
The patent makes the beam writing system and fabrication process universal by designing them to handle multiple grating types and orientations using the same basic process. A single coating layer and single writing system perform multiple functions, writing different diffraction gratings for various optical purposes without requiring separate specialized processes.
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
Significantly reduces the time required to fabricate diffraction grating patterns, improving the efficiency of producing optical image light guides for virtual image near-eye display systems.
Implementation Method 1
a beam writing system operable to write in a first direction and a second direction, wherein the second direction is perpendicular to the first direction
Implementation Method 2
the first diffraction grating includes a first plurality of diffractive features, the second diffraction grating includes a second plurality of diffractive features, and the third diffraction grating includes a third plurality of diffractive features
Data Source
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AI summary
A substrate (40, 70, 90, 220) comprises a first planar surface (46, 92) and a second planar surface (46, 92). A first diffraction pattern is arranged along one of said first and second planar surfaces (46, 92), wherein said first diffraction pattern includes a first plurality of diffractive features (50). A second diffraction pattern is arranged along one of said first and second planar surfaces (46, 92), wherein said second diffraction pattern includes a second plurality of diffractive features (50). At least one of said first and second pluralities of diffractive features (50) comprise stepped line diffractive features (52). A virtual image near-eye display system comprises at least one planar waveguide including the substrate (40, 70, 90, 220). A beam writing system comprises a first platform operable to translate in x and y directions and a second platform operable to rotate about a perpendicular axis, wherein the substrate (40, 70, 90, 220) is coupled to the beam writing system.