AR Waveguide Diffractive Gratings With Height-Modulated Deposition
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Solution Overview
Problem
Existing methods for fabricating augmented reality eyewear diffractive gratings face limitations in modulating scattering intensity across the grating arrangement, requiring complex fabrication processes and additional steps like deposition of additional layers and multiple etching, leading to increased costs and reduced process yield.
Innovation Solution
A method to control the local thickness of diffraction grating features with a high refractive index by using a deposition process through a perforated plate at a controlled distance, allowing for one-step etching to form gratings with varying heights, eliminating the need for additional steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If standard fabrication methods (variation in grating pattern) are used to modulate scattering strength, then the grating pattern can be varied, but the scattering intensity modulation is insufficient (cannot achieve factor of 10 or more)
Solution Approach 1:
The patent applies local quality by varying the height of grating features at different locations across the diffractive grating arrangement. This allows each region to have optimized scattering properties tailored to specific requirements, achieving scattering intensity modulation factors of 10 or more that cannot be obtained through grating pattern variation alone.
Solution Approach 2:
The patent transitions from two-dimensional grating pattern variation to three-dimensional height modulation. By controlling the vertical dimension (grating feature height) in addition to lateral pattern variations, the system achieves superior scattering intensity control with modulation factors exceeding 10, resolving the limitation of standard fabrication methods.
2Manufacturing precision
If controllable variation in height of grating features is implemented to achieve strong scattering modulation, then scattering intensity can be modulated by factor of 10 or more, but fabrication complexity increases requiring additional deposition layers, multiple etching steps, and grayscale lithography
Solution Approach 1:
The patent merges the height variation function into a single deposition step using a shadow mask with varying thickness, rather than requiring separate deposition layers. This consolidation eliminates multiple etching steps and grayscale lithography, reducing fabrication complexity while maintaining the capability to achieve scattering intensity modulation factors of 10 or more.
Solution Approach 2:
The patent performs preliminary action by pre-forming the shadow mask with spatially varying thickness before the deposition process. This pre-prepared mask structure enables direct one-step deposition that creates the desired height variations in grating features, eliminating the need for subsequent complex multi-step fabrication processes.
3Manufacturing precision
If complex fabrication sequences with multiple etching steps and additional layers are used, then grating feature height variation can be achieved, but process yield suffers and fabrication costs increase
Solution Approach 1:
The patent extracts the height variation control function from complex multi-step fabrication sequences and concentrates it into a single deposition step using a specially designed shadow mask. This extraction eliminates multiple etching steps and additional layer depositions, thereby improving process yield and reducing fabrication costs while maintaining precise grating feature height control.
Solution Approach 2:
The patent employs a shadow mask that can be used for multiple deposition runs, replacing the need for expensive and complex reusable fabrication tooling. The shadow mask achieves precise height control in a cost-effective manner, improving both process yield and reducing fabrication costs compared to complex fabrication sequences.
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
Enhances scattering efficiency modulation and improves manufacturability by simplifying the fabrication process, reducing costs, and maintaining high image quality with better image uniformity and contrast.
Implementation Method 1
at least one layer of solid material through perforations of a plate at a non-zero distance from the waveguide is deposited on the waveguide
Data Source
Figure 1A~1B
Figure 2~4
Figure 5A~8
AI summary
A manufacturing method of an optical element (10) of an augmented reality eyewear. At least one layer (300) of a material (200) is deposited on a waveguide (106) through perforations (204) of a plate (202) at a non-zero distance (D) from the waveguide (106). Height of the at least one layer (300) is made to vary in response to cross sectional areas of the perforations (204), which vary based on a location of the perforations (204) in the plate (202) for forming at least one diffractive grating (100, 102, 104) on the waveguide (106) from the at least one layer (300), the at least one diffractive grating (100, 102, 104) performing in-coupling and/or out-coupling of visible light between the waveguide (106) and environment.