Lithium-Oxide Diffractive Waveguides for Comfortable AR Depth Cues
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Solution Overview
Problem
Conventional augmented reality (AR) and virtual reality (VR) systems struggle to provide a comfortable and realistic perception of depth due to mismatches between accommodative and vergence states, leading to user discomfort.
Innovation Solution
The use of high refractive index waveguides with diffraction gratings formed from lithium-based oxides, combined with a stacked waveguide assembly that provides continuous vergence cues and discrete accommodation cues, simulating three-dimensional imagery by adjusting wavefront divergence to match physiological responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used to create diffractive optical elements, then the manufacturing process is simpler, but the feature size and depth precision are insufficient for visible light diffraction
Solution Approach 1:
The patent changes the etching parameters by using a specific gas mixture (CHF3 and CF4 in a 9:1 ratio) and controlling the etching conditions to achieve precise feature sizes and depths that enable visible light diffraction, transforming the etching process from a simple removal method to a precision fabrication tool
Solution Approach 2:
The patent uses a composite gas mixture of CHF3 and CF4 during the etching process, where the combination of these two gases provides both the precision needed for visible light diffraction and the control required for feature formation, achieving superior results compared to using either gas alone
2Reliability
If the lithium-based oxide layer is etched to create diffractive features, then the diffractive optical element functionality is achieved, but the etch mask pattern complexity increases
Solution Approach 1:
The patent applies local quality by creating etch mask patterns with specific local characteristics that expose only the necessary regions of the lithium-based oxide layer, allowing the etching process to selectively form diffractive features with the required precision while managing overall pattern complexity
3Productivity
If conventional etching processes are used, then the manufacturing process is faster, but the etched features cannot effectively diffract visible light
Solution Approach 1:
The patent optimizes etching parameters including gas flow ratios (CHF3:CF4 = 9:1), temperature, and pressure to achieve a balance where the etching process maintains high productivity while simultaneously achieving the precise feature dimensions and depths required for effective visible light diffraction
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 approach enhances the realism and comfort of depth perception by aligning accommodative and vergence states, providing a more natural and immersive AR/VR experience.
Implementation Method 1
plasma etching the exposed regions of the substrate using a gas mixture comprising CHF3 to form a diffractive optical element
Data Source
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Figure 3A~3C
AI summary
The present disclosure generally relates to display systems, and more particularly to augmented reality display systems and methods of fabricating the same. A method of fabricating a display device includes providing a substrate comprising a lithium (Li)-based oxide and forming an etch mask pattern exposing regions of the substrate. The method additionally includes plasma etching the exposed regions of the substrate using a gas mixture comprising CHF3 to form a diffractive optical element, wherein the diffractive optical element comprises Li-based oxide features configured to diffract visible light incident thereon