Transparent Conductive Waveguide Gratings for AR/VR Stray Light

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Solution Overview

Problem

Stray light issues in waveguides of augmented and virtual reality headsets are exacerbated by the challenges of fabricating wire grid polarizers, which are prone to warping and require additional space, complicating the integration of polarizers in diverse environments.

Innovation Solution

The use of transparent conductive materials, such as fluorinated tin oxide (FTO) and indium tin oxide (ITO), to create diffractive gratings that absorb stray light while functioning as polarizers, eliminating the need for separate space on the waveguide and reducing fabrication complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If wire grid polarizers are used to absorb stray light, then light absorption capability is improved, but fabrication difficulty increases and structural stability deteriorates

Engineering Contradiction:

Improvestray lightVSAvoidfabrication difficulty

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent changes the material parameters from traditional wire grid materials to transparent conductive oxides (TCOs) such as ITO, AZO, and ZNO. These materials offer different optical and electrical properties that enable effective stray light absorption while being compatible with standard waveguide fabrication processes, thus resolving the fabrication difficulty issue

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite structures combining transparent conductive oxide layers with dielectric materials. This composite approach maintains the polarizing function while improving structural stability and eliminating the warping issues associated with wire grid polarizers, as the rigid dielectric substrate provides mechanical support

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If wire grid polarizers are used to absorb stray light, then light absorption capability is improved, but structural stability deteriorates

Engineering Contradiction:

Improvestray lightVSAvoidstructural stability

Core Design Contradiction:

Object-affected harmful factorsVSStability of the object's composition

Solution Approach 1:

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent replaces the mechanical wire grid structure with a thin-film deposited layer of transparent conductive oxide. This substitution eliminates the mechanical warping problem inherent in wire grids while maintaining the electrical and optical properties necessary for stray light absorption through plasma oscillation mechanisms

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Object-affected harmful factors

If wire grid polarizers are used to absorb stray light, then light absorption capability is improved, but device complexity increases

Engineering Contradiction:

Improvestray lightVSAvoiddevice complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges the polarizing function with the existing waveguide structure by depositing transparent conductive oxide layers directly onto the waveguide substrate. This integration eliminates the need for separate wire grid polarizer components and their associated mounting hardware, thereby reducing overall device complexity while maintaining stray light absorption capability

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The transparent conductive oxide layer serves multiple functions simultaneously: it acts as a polarizer for stray light absorption, maintains waveguide structural integrity, and can be integrated with other waveguide components. This multi-functionality reduces the number of separate components needed, simplifying the overall device architecture

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS12504566B2Transparent conductive diffractive gratings for optical elements of augmented reality and virtual reality displays

Publication Date: 2025.12.23 ADEIA GUIDES INC

AI summary

Head-mounted displays with waveguides comprising surface relief gratings made of a transparent conductive material and methods for fabricating said waveguides are described herein. In an embodiment, a head-mounted display comprises an optical element and an image source that provides an image beam to an optical element. The optical element comprises a diffractive grating comprising a transparent conductive material. The diffractive grating diffracts light into, through, or out of the waveguide as well as absorbing any light that is not polarized in the direction of the diffractive grating.