Switchable Waveguide Optics Focus Elements for AR Displays
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Solution Overview
Problem
Current focus adjustment systems in augmented reality near-eye displays are inadequate due to mechanical noise, high power consumption, slow response to eye movement, and image quality issues, leading to viewer eye strain and fatigue.
Innovation Solution
The implementation of switchable waveguide optics focus elements, such as Switchable Bragg Gratings, which allow for adjustable focus depth by integrating multiple diffractive devices within the waveguide to align the virtual image with the environment's focal distance, reducing the need for mechanical adjustments and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If mechanical mechanisms are used to adjust focus, then focus adjustment capability is achieved, but device complexity increases, power consumption increases, and response speed decreases
Solution Approach 1:
The patent replaces mechanical focus adjustment mechanisms with an optical system using Alvarez lenses positioned on either side of a waveguide. The lenses are adjusted by moving the waveguide relative to the lenses, eliminating complex mechanical focus adjustment mechanisms while maintaining focus capability.
Solution Approach 2:
The waveguide acts as an intermediary element between the Alvarez lenses and the user's eye. It combines real object light and display light, allowing focus adjustment through relative movement between the waveguide and lenses rather than direct mechanical adjustment of the lenses themselves.
2Ease of operation
If Alvarez lenses are used for focus adjustment, then focus capability is improved, but image quality deteriorates due to distortion
Solution Approach 1:
The Alvarez lenses are designed with specific zone structures where different regions serve different functions. The lenses have optimized optical properties in different zones to reduce distortion while maintaining focus capability, improving overall image quality.
Solution Approach 2:
The system uses dynamic adjustment of the waveguide position relative to the Alvarez lenses to achieve focus at different depths. This dynamic positioning allows the optical system to maintain image quality across various focus settings by optimizing the light path through the waveguide.
3Device complexity
If fixed focus LCD lenses are used, then device complexity is reduced, but response speed decreases and adaptability worsens
Solution Approach 1:
The system replaces fixed-focus LCD lenses with a dynamic optical system using Alvarez lenses and a movable waveguide. The waveguide can be quickly repositioned relative to the lenses to adjust focus, enabling rapid response to eye movement while maintaining relatively simple device architecture.
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 enhances user experience by reducing eye strain and fatigue through improved focus accommodation, allowing virtual images to appear at correct focal distances, thus providing more realistic augmented reality imaging without the limitations of traditional focus systems.
Implementation Method 1
the first lens focuses the real object to focus infinity, the light is combined with the display light in the waveguide, and the second lens focuses back to the original viewing distance
Implementation Method 2
a waveguide for viewing of an environment that is viewable with the imaging structure. The waveguide combines light of a virtual image with the transmitted light of the environment
Implementation Method 3
A first switchable output diffractive device is implemented to focus the virtual image at infinity when switched-on, yet allow light to continue propagating down the waveguide when switched-off. This first switchable output diffractive device has simple wedge power to diffract light that is propagating in the waveguide
Data Source
AI summary
In embodiments of waveguide optics focus elements, an imaging structure includes a waveguide for viewing of an environment that is viewable with the imaging structure. The waveguide transmits light of a virtual image that is generated to appear as part of the environment for augmented-reality imaging or virtual-reality imaging. The imaging structure also includes one or more focus elements that are integrated in the waveguide and switchable to focus the virtual image at a focus depth that approximately correlates to a focal distance of the environment. The focus elements can each be implemented for a different focus depth of the virtual image, and the focus depth is adjustable based on a combination of the focus elements being switched-on or switched-off.