Blackened Waveguide Sidewalls for AR Stray Light Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing waveguides face challenges in suppressing unwanted light leakage and improving image contrast and visual clarity due to stray light transmission and scattering at sidewalls, which degrade the quality of virtual images in augmented reality systems.
Innovation Solution
A waveguide design incorporating a blackening layer on the exterior portion of a grating layer and sidewalls, along with a blackening section on the waveguide substrate sidewall, utilizing an optically absorbent composition with specific refractive indices to absorb stray light and reduce reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a waveguide is used to propagate light for augmented reality display, then light transmission and image overlay are enabled, but unwanted light leakage and stray light scattering occur at sidewalls degrading image contrast
Solution Approach 1:
The patent applies a blackening layer containing optically absorbent particles to the sidewalls of the waveguide. This converts the harmful stray light that would otherwise scatter and degrade image contrast into absorbed energy, eliminating the harmful effect. The blackening layer transforms the problem of light leakage into a beneficial absorption mechanism that enhances image quality by selectively absorbing unwanted stray light while maintaining desired light propagation.
2Illumination intensity
If the waveguide substrate sidewall is left uncoated, then manufacturing simplicity is maintained, but light leakage and scattering occur reducing visual clarity
Solution Approach 1:
The patent applies the blackening layer specifically to the sidewall regions of the waveguide where light leakage and scattering occur, rather than coating the entire waveguide structure. This localized application targets the specific problem areas (sidewalls adjacent to the grating layer) while leaving other regions unchanged, thereby improving visual clarity only where needed and minimizing the addition of device complexity.
3Object-generated harmful factors
If a blackening layer is applied to the exterior portion of the grating layer and sidewalls, then stray light absorption is improved, but manufacturing complexity increases
Solution Approach 1:
The patent specifies particular refractive index ranges for the optically absorbent particles in the blackening layer (e.g., 1.4-1.8 for visible light wavelengths). By defining specific parameter ranges for the coating material, the patent optimizes stray light absorption effectiveness while providing clear manufacturing specifications that facilitate consistent production. This parameter-based approach balances performance improvement with manufacturing feasibility.
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 minimizes stray light transmission and scattering, enhancing image contrast and clarity by absorbing stray light, thereby improving the overall performance of augmented reality waveguides.
Implementation Method 1
a blackening layer disposed over an exterior portion of the waveguide substrate... effectively minimizes stray light transmission and scattering, enhancing image contrast and clarity by absorbing stray light
Data Source
AI summary
Embodiments of waveguides are described herein. A waveguide of one or more embodiments includes a waveguide substrate having a first surface, a second surface opposing the first surface, a waveguide substrate sidewall connecting the first surface to the second surface, a grating layer disposed over the first surface, a blackening layer disposed over an exterior portion of the waveguide substrate, and a blackening section disposed on the waveguide substrate sidewall. The grating layer includes at least an input coupling grating and an output coupling grating disposed therein. The grating layer includes an interior portion surrounding the input coupling grating and the output coupling grating.