Curved Graded-Index Waveguides for AR Display Distortion
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Solution Overview
Problem
Curved waveguides in head-mounted display devices, such as augmented reality glasses, face the challenge of wavefront error due to total internal reflection, leading to beam distortion, especially for modest waveguide curvatures, which affects the angular distribution of light and image clarity.
Innovation Solution
A polymeric waveguide with a curved cross-section and a graded refractive index profile, where the refractive index varies spatially through the thickness, is designed to compensate for curvature, using methods like resin co-flow, chemical vapor deposition, or diffusion techniques to create a refractive index profile that minimizes distortions by bending rays appropriately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a curved waveguide is used to achieve compact form factor and proper light routing, then the device can be integrated into head-mounted displays, but wavefront error and beam distortion occur due to total internal reflection
Solution Approach 1:
The waveguide implements a graded refractive index profile where the refractive index varies spatially across the waveguide thickness (higher at curved surfaces, lower at the center). This local variation in optical properties compensates for the wavefront errors introduced by curvature, reducing beam distortion while maintaining the compact curved geometry
Solution Approach 2:
The patent changes the refractive index parameter across the waveguide cross-section to correct optical distortions. By creating a gradient in the refractive index (n(r) = n0 + n2*r^2), the system compensates for the path length differences and wavefront errors caused by the curved geometry, thereby reducing image distortion
2Manufacturing precision
If a graded refractive index profile is implemented to compensate for curvature effects, then beam distortion is reduced, but the manufacturing complexity increases
Solution Approach 1:
The waveguide uses a composite structure combining materials with different refractive indices (e.g., silica core with fluorinated cladding or polymer layers). This composite approach creates the graded refractive index profile through material composition rather than requiring complex processing of a single material, thereby achieving the desired optical correction with feasible manufacturing
Solution Approach 2:
The patent introduces an intermediary layer or gradient region between the high-index curved surfaces and the low-index center. This intermediary structure (achieved through controlled diffusion, deposition, or layering) provides a smooth transition in refractive index that compensates for curvature effects while using standard fabrication techniques
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 solution effectively reduces image distortions caused by waveguide curvature, ensuring that inputted light carries an image in the angular domain without significant distortions, improving the clarity and accuracy of displayed images in head-mounted displays.
Implementation Method 1
the refractive index spatially varying through a thickness between the first curved surface and the second curved surface... bending rays appropriately
Implementation Method 2
Light input into the plate propagates along the length of the plate as long as the light continues to be incident at boundaries between the plate and the surrounding medium at an angle above the critical angle
Implementation Method 3
allowing the first resin and the second resin to diffuse into one another to form a composite resin structure in which a ratio of the second resin to the first resin in the composite resin varies in a thickness direction
Implementation Method 4
introducing a monomer-containing vapor into the deposition chamber and depositing material from the monomer-containing vapor onto a surface of the substrate
Implementation Method 5
polymerizing the material deposited on the substrate
Data Source
AI summary
Disclosed is a polymeric waveguide for propagating light therein along width and length dimensions of the polymeric waveguide. The polymeric waveguide has a first curved surface on one side thereof and a second curved surface on an opposite second side thereof, and a refractive index spatially varying through a thickness thereof between the first curved surface and the second curved surface. The polymeric waveguide is curved in a cross-section comprising at least one of the width and length dimensions.