View Control Layer for AR Waveguide Diffraction Artifacts
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Solution Overview
Problem
Augmented reality (AR) display systems using diffractive backlights suffer from rainbow artifacts and color non-uniformity due to external light sources, which distract users and reduce the perceived quality of the display.
Innovation Solution
A wearable heads-up display (WHUD) device incorporates a view control layer, such as a light control film, polarization stack, or dielectric stack angular filter, optically coupled to a waveguide to selectively prevent light rays from interfacing with diffraction structures based on their angle of incidence, thereby reducing high-angle light interference and diffraction artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If diffractive backlights are used in AR display systems, then light can be temporally modulated to provide display content, but rainbow artifacts and color non-uniformity occur due to external light sources interfacing with diffraction structures
Solution Approach 1:
A view control layer is introduced as an intermediary component between the external environment and the waveguide diffraction structures. This layer selectively blocks high-angle external light rays before they can reach the diffraction structures, preventing rainbow artifacts while allowing low-angle display light to pass through unchanged to maintain image quality and brightness.
Solution Approach 2:
The view control layer implements angle-dependent light control with different properties for different incident angles. It allows low-angle light (display content) to pass through with high transmission while blocking high-angle light (external sources) to prevent artifacts. This local quality differentiation resolves the contradiction by treating different light paths differently based on their angle of incidence.
2Object-affected harmful factors
If view control layer is added to block high-angle light rays, then diffraction artifacts are reduced, but device complexity increases
Solution Approach 1:
The view control layer is implemented as a thin film or coating applied to the waveguide surface, rather than a bulky mechanical component. This thin-film approach provides the necessary angle-selective light blocking functionality while adding minimal complexity to the overall device structure, maintaining a compact and integrated optical system.
Solution Approach 2:
The patent replaces potential mechanical angle-selection mechanisms with an optical filter layer that uses material properties (refractive index, absorption characteristics) to achieve angle-dependent light control. This substitution eliminates complex mechanical structures while achieving the same artifact reduction goal through optical physics.
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 rainbow artifacts and enhances color uniformity by limiting the range of angles for external light beams to pass through the waveguide, maintaining high transmission in the user's field of view and reducing diffraction artifacts, thus improving the overall AR display experience.
Implementation Method 1
the view control layer to selectively prevent light rays from interfacing with at least one diffraction structure of the one or more diffraction structures based on a respective angle of incidence at which the light rays encounter the view control layer
Implementation Method 2
light is temporally modulated to provide a pattern of light, which is spatially distributed over a two-dimensional display area. The spatial distribution of the modulated pattern of light produces an image at the display area
Data Source
AI summary
Techniques are described in which a view control layer is optically coupled to a waveguide having one or more diffraction structures. The view control layer selectively prevents light rays from interfacing with at least one diffraction structure of the waveguide based on a respective angle of incidence at which the light rays encounter the view control layer. In various embodiments, the view control layer may include a light control film, a polarization stack, and/or a dielectric stack angular filter.