Slanted Grating Fabrication Using Crystal-Plane Etching
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Solution Overview
Problem
Conventional augmented reality (AR) and virtual reality (VR) systems struggle to provide a comfortable and realistic presentation of virtual image elements amidst real-world imagery due to mismatches between accommodative and vergence states, leading to user discomfort.
Innovation Solution
The fabrication of slanted gratings in optical components, such as waveguides, to manipulate light wavefront divergence and align it with the human visual system's accommodative and vergence cues, thereby enhancing the perception of depth and comfort in AR and VR experiences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional AR/VR systems present virtual image information, then digital or virtual images can be displayed to users, but mismatches between accommodative and vergence states occur leading to user discomfort
Solution Approach 1:
The patent changes the physical parameters of the diffraction grating, specifically the slant angle of the grating lines, to control the wavefront divergence of outgoing light. By adjusting the slant angle parameter, the system can match different vergence states with corresponding accommodative states, resolving the comfort issue without adding complex mechanical adjustment mechanisms
Solution Approach 2:
The patent applies different slant angles to different regions or types of gratings within the optical system. Specifically, the in-coupling grating and out-coupling grating have different slant angles optimized for their respective functions, allowing precise control over light wavefront properties at different locations to achieve overall system comfort
2Manufacturing precision
If slanted gratings are fabricated using conventional etching methods, then gratings can be formed, but the crystallographic planes of the substrate are not utilized resulting in less precise grating geometry
Solution Approach 1:
The patent utilizes the self-organizing properties of crystallographic planes during the etching process. The etchant naturally follows the crystallographic orientation of the substrate, automatically forming trenches with precise angles defined by the crystal structure. This eliminates the need for complex alignment and control mechanisms, as the substrate itself guides the etching process to achieve high precision
Solution Approach 2:
The patent replaces mechanical alignment and control systems with a chemical etching process that leverages the inherent crystallographic structure. Instead of using mechanical means to precisely control trench angles, the system uses chemical etching where the crystallographic planes naturally determine the trench geometry, simplifying the manufacturing process while achieving high precision
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
The slanted gratings improve the alignment of accommodative and vergence states, providing a more realistic and comfortable three-dimensional imagery by matching physiological cues, reducing user discomfort and enhancing depth perception.
Implementation Method 1
etching the plurality of first trenches with an etchant having an etch rate for a first crystalline plane of the substrate that is greater than for a second crystalline plane of the substrate
Data Source
AI summary
A method includes patterning a plurality of first trenches in a surface of a substrate; and etching the plurality of first trenches with an etchant having an etch rate for a first crystalline plane of the substrate that is greater than for a second crystalline plane of the substrate. The etching forms a slanted grating in the substrate.