Variable Focus Element Corrects Field Curvature in Multi-Focal Displays
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Solution Overview
Problem
Current augmented reality systems face challenges in presenting 3D virtual content by accurately creating perceptions of multiple depths, as they struggle to deliver virtual content at different focal planes relative to the user, leading to issues with field curvature and focus alignment.
Innovation Solution
The use of a variable focus element (VFE) coupled with switchable screens, such as polymer-dispersed liquid crystal diffusers, to modulate the wavefront of light and correct field curvature, allowing for multi-focal 3D imagery by adjusting the optical power in coordination with the scanning pattern, thereby enabling a compact, high-speed focus modulation system that supports a large eyebox and corrects field curvature dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a variable focus element is used to deliver virtual content at different focal planes, then 3D perception is improved, but field curvature and focus alignment deteriorate
Solution Approach 1:
The patent divides the display field into multiple zones corresponding to different depth planes. Each zone is assigned to a specific focal plane, allowing the system to present content at multiple focal distances simultaneously. This segmentation resolves the contradiction by enabling multi-focal capability while maintaining proper focus alignment through zone-based content assignment.
Solution Approach 2:
The patent employs a dynamically adjustable variable focus element that can change its optical power in real-time. The VFE is controlled to match the focal requirements of different scan positions, dynamically correcting field curvature as the scanning pattern moves across different depth planes. This dynamic adjustment maintains focus alignment while preserving multi-focal versatility.
2Manufacturing precision
If field curvature is corrected using traditional optical methods, then focus alignment is improved, but system complexity and size increase
Solution Approach 1:
The patent replaces traditional mechanical optical correction systems with a variable focus element controlled by electrical signals. Instead of using complex mechanical lens assemblies or multiple optical elements to correct field curvature, the system uses an electronically controllable VFE that can be programmed to match focal requirements, significantly reducing system complexity while maintaining focus alignment precision.
Solution Approach 2:
The patent changes the optical parameters of the VFE dynamically based on the scanning pattern and desired focal planes. By adjusting the optical power parameter of the VFE in coordination with the scanning device, the system achieves field curvature correction without requiring complex fixed optical systems. This parameter-based control simplifies the overall optical 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 allows for a compact and efficient optical system that achieves excellent field flatness and multi-focal display, enabling a viewer to perceive 3D volumetric images with objects at different focus levels and viewing distances, while maintaining low power consumption and high-speed focus modulation.
Implementation Method 1
modulate the wavefront of light and correct field curvature
Implementation Method 2
variable focus element (VFE) coupled with switchable screens to modulate the wavefront of light
Implementation Method 3
switchable screens, such as polymer-dispersed liquid crystal diffusers, to modulate the wavefront of light
Data Source
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AI summary
Configurations are disclosed for presenting virtual reality and augmented reality experiences to users. The system may comprise an image generating processor to providing one or more frames of image data, a light modulator to transmit light associated with the one or more frames of image data, a plurality of switchable screens having a range of numerical apertures to vary an effective numerical aperture associated with the one or more frames of image data, and a variable focus element (VFE) to vary a focus of the one or more frames of image data on one of the switchable screens of the plurality of switchable screens.