Curved Waveguide Fabrication via Rotated Mold NIL
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Solution Overview
Problem
Conventional methods for fabricating waveguides for portable display devices, such as smart glasses, require flat substrates, limiting the use of curved waveguides that could enhance comfort and reduce form factor.
Innovation Solution
A method and apparatus for forming curved waveguides using a mold with a surface-relief pattern and a substrate with a curved surface, where the substrate is rotated to imprint the pattern onto a patternable film, allowing for the creation of self-supporting waveguides with a curved interface region and a patterned outer surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conventional NIL fabrication methods are used with flat substrates, then manufacturing precision and rigidity are ensured, but the waveguide cannot be curved limiting comfort and form factor
Solution Approach 1:
The patent applies curvature to the waveguide substrate to create a curved waveguide body that can be formed from a curved planar substrate. This allows the waveguide to follow the curvature of the eye or face, improving comfort and reducing form factor in portable display devices while maintaining manufacturability through adapted NIL processes.
Solution Approach 2:
The patent changes the geometric parameters of the substrate from flat to curved configurations. By adjusting the curvature radius and other geometric parameters of the substrate before patterning, the method enables formation of curved waveguides with controlled optical properties while maintaining compatibility with industrial-scale NIL fabrication.
2Ease of operation
If curved waveguides are fabricated, then comfort and form factor are improved, but manufacturing precision and structural rigidity become challenging
Solution Approach 1:
The patent uses curved planar substrates that can be accurately patterned using NIL, then formed into three-dimensional curved waveguide structures. This approach maintains manufacturing precision during the patterning stage while achieving the desired curvature for improved comfort and reduced form factor in the final waveguide.
Solution Approach 2:
The fabrication process is segmented into distinct stages: (1) patterning the curved planar substrate using NIL to create the surface relief structure, (2) forming the three-dimensional curved waveguide shape, and (3) coating with index-matching material. This segmentation allows each stage to be optimized independently, maintaining precision while achieving curvature.
3Adaptability or versatility
If surface-relief gratings are used for optical elements, then versatility and adjustability are improved, but fabrication complexity increases
Solution Approach 1:
The patent uses a universal NIL-based patterning approach that can create different types of surface-relief gratings (in-couplers, out-couplers, exit pupil expanders) by simply changing the mold design. This single fabrication method provides versatility and adjustability of SRG parameters without increasing overall fabrication complexity, as the same basic process applies to all grating types.
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
Enables the production of curved waveguides suitable for portable display devices, improving comfort and reducing the form factor while maintaining rigidity and durability, facilitating industrial-scale manufacturing.
Implementation Method 1
The waveguide is configured to propagate light coupled into the waveguide by total internal reflection
Data Source
AI summary
A waveguide (1000) configured to propagate light (1001) by total internal reflection, a display device, as well as a method and an apparatus for forming a waveguide are disclosed. The waveguide (1000) comprises a waveguide body (1100) comprising a first face (1110) and a second face (1120) opposite the first face (1110); and a coating (1200) on the first face (1110), the coating (1200) comprising an outer surface (1210) facing away from the first face (1110). The first face (1110) comprises a curved interface region (1111) between the waveguide body (1100) and the coating (1200), and the outer surface (1210) comprises a curved outer region (1211) opposite the interface region (1111). The outer region (1211) comprises a patterned region (1212), and the coating (1200) comprises on the outer surface (1210) a surface relief structure (1220) defining the patterned region (1212).