Waveguide-Based Optical Systems for Augmented Reality

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Solution Overview

Problem

Conventional augmented reality (AR) optical systems using light guides have limitations such as a narrow field of view, strict geometrical tolerances, and discrete light outcoupling, making them unsuitable for compact and high-quality AR eyewear designs.

Innovation Solution

A waveguide-based AR optical system with a substrate-supported waveguide layer containing input and output gratings that provide phase matching, allowing input light to be coupled and outcoupled continuously, enabling a larger field of view and more flexible design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If conventional light guides are used in AR systems, then the design can be compact, but the field of view is limited to 30°-50° and geometrical tolerances must be very tight (micron scale)

Engineering Contradiction:

Improvethickness of light guideVSAvoidgeometrical tolerances

Core Design Contradiction:

Volume of moving objectVSManufacturing precision

Solution Approach 1:

The patent transitions from geometric optics to waveguide optics, fundamentally changing the optical parameter regime. This allows the light guide thickness to be reduced from millimeter scale to micrometer scale (1-100 μm) while simultaneously relaxing the geometrical tolerance requirements through wave-based coupling mechanisms rather than ray-based geometric constraints

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical/geometric light guide structure with a waveguide structure that operates on electromagnetic wave principles. The input and output gratings use diffraction and phase matching to couple light in and out of the waveguide layer, substituting geometric optical paths with wave-based optical control

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If conventional light guides are used in AR systems, then the structure is simple, but the light outcoupling is discrete rather than continuous over the output region

Engineering Contradiction:

Improvestructural complexityVSAvoidlight outcoupling quality

Core Design Contradiction:

Device complexityVSEase of operation

Solution Approach 1:

The patent implements continuous light outcoupling along the entire output grating region by using waveguide modes that propagate continuously through the waveguide layer. The output grating couples these guided modes out continuously along its length, providing uniform light distribution across the output region rather than discrete outcoupling points

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The patent introduces guided modes as an intermediary between the input light and the output light. The input grating couples light into guided modes that propagate through the waveguide layer, and the output grating couples these guided modes out continuously, creating a smooth continuous light distribution at the output

Inventive Principle:

Principle #24Intermediary (Mediator)

3Volume of moving object

If waveguide layer thickness is reduced to 1-100 μm, then the AR system becomes slimmer and more flexible, but the index of refraction difference requirement (nG−nS≥0.5) becomes more stringent

Engineering Contradiction:

Improvewaveguide layer thicknessVSAvoidmaterial selection flexibility

Core Design Contradiction:

Volume of moving objectVSAdaptability or versatility

Solution Approach 1:

The patent reduces the waveguide layer thickness to 1-100 μm to achieve a slimmer and more flexible AR system. This thickness reduction enables the system to be more adaptable to different form factors and wearable configurations, while the specific parameter range is optimized to maintain waveguide functionality

Inventive Principle:

Principle #35Parameter changes

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 results in a slim, flexible, and cost-effective AR optical system with a wider field of view (up to 70°) and continuous light extraction, enhancing image quality and usability in AR eyewear.

Implementation Method 1

The input light is coupled into the waveguide layer and travels therein as multiple guided modes to the output grating

Methodology Applied

Scientific EffectDiffraction: Diffraction

Implementation Method 2

The input light is coupled into the waveguide layer and travels therein as multiple guided modes

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 3

The input and output gratings provide phase matching so that the guided modes are coupled out of the waveguide layer by the output grating continuously along the output grating

Methodology Applied

Scientific EffectDiffraction: Diffraction

Data Source

PatentUS10929667B2Waveguide-based optical systems and methods for augmented reality systems

Publication Date: 2021.02.23 CORNING INC

AI summary

An augmented reality optical system comprises a waveguide structure that includes a waveguide layer supported by a substrate. An input grating and an output grating reside within the waveguide layer and are laterally spaced apart. Input light from a display is made incident upon the input grating. The input light is coupled into the waveguide layer and travels therein as multiple guided modes to the output grating. The input and output gratings provide phase matching so that the guided modes are coupled out of the waveguide layer by the output grating continuously along the output grating to form output light. Meantime, light from a scene is transmitted perpendicularly through the output grating so that the output light and the light from the scene are combined by the eye of a user to form an augmented reality image.