Staircase Waveguide Element for AR Display Integration
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Solution Overview
Problem
Existing waveguides for augmented reality, virtual reality, and mixed reality devices face challenges in integrating diffractive elements with corrective or non-corrective lenses due to the tight coupling of optical properties with physical shape, limiting design flexibility and visual appeal.
Innovation Solution
A diffractive waveguide element with staircase profiles that decouples the waveguide geometry from the surface it follows, allowing for arbitrary outer surface shapes while maintaining optical functionality, enabling the creation of 'optically planar' or 'non-planar' display elements that can fit snugly onto spectacle lenses or other curved surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conventional waveguides are used with spherical or aspherical shapes, then the waveguide can follow curved surfaces, but the optical properties are tightly coupled with the physical shape, limiting design flexibility
Solution Approach 1:
The waveguide surface is segmented into discrete planar facets arranged in a staircase configuration. Each facet is a separate planar surface that collectively approximates a curved shape, allowing the waveguide to follow curved surfaces while maintaining locally planar optical properties at each facet level
Solution Approach 2:
The invention transitions from continuous curved surfaces to discrete stepped surfaces by adding a vertical dimension to the staircase structure. This dimensional transformation allows the waveguide to achieve both curved overall shape and locally planar optical surfaces through the stepped configuration
2Adaptability or versatility
If diffractive waveguide displays are integrated with corrective lenses, then spectacle form-factor devices can be created, but the tight coupling of optical properties with physical shape prevents effective integration
Solution Approach 1:
The staircase waveguide structure serves multiple functions: it provides the curved shape needed to fit spectacle lenses, maintains planar optical surfaces for effective diffractive element integration, and enables both corrective and display optical functions within a single unified structure
Solution Approach 2:
Different regions of the waveguide have different properties: the overall structure follows a curved shape to match the lens surface, while local facets remain planar to support diffractive elements, allowing each region to optimize for its specific function
3Shape
If the waveguide follows an arbitrary surface shape, then visual appeal and form-factor requirements are met, but the optical performance suffers due to shape-optics coupling
Solution Approach 1:
The arbitrary surface shape is segmented into discrete planar facets that collectively approximate the desired curve. Each facet maintains planarity for reliable optical performance, while the segmented arrangement collectively achieves the arbitrary surface shape for visual appeal and form-factor compliance
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 solution provides greater design freedom, allowing for the creation of waveguide-based display devices that can match arbitrary surface shapes without compromising optical performance, enabling improved user experience and visual appeal in near-to-the-eye applications like smart glasses.
Implementation Method 1
a waveguide region defined by two optical surfaces between which light can propagate by total internal reflections
Implementation Method 2
at least one diffractive optical element (DOE), in particular a grating, capable of modifying the light field within the waveguide region
Data Source
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AI summary
The invention provides a diffractive waveguide element, waveguide stack, personal display and method of forming a viewable image. The element comprises a waveguide region (102) defined by two optical surfaces (102A/B) between which light can propagate by total internal reflections, the optical surfaces (102A/B) having surface profiles, and at least one diffractive grating capable of modifying the light field within the waveguide region (102). According to the invention, the surface profile of at least one of said optical surfaces (102A/B) is a staircase profile.