Polarization-Based Dynamic Focuser for Near-Eye Displays
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Solution Overview
Problem
Near-eye display devices (NEDs) face the challenge of vergence-accommodation mismatch, where the eyes' focus on real-world objects and virtual imagery are decoupled, leading to disorientation, headaches, and nausea due to the inability to dynamically change the apparent focal depth of virtual imagery without affecting environmental light.
Innovation Solution
A polarization-based dynamic focuser is introduced, comprising a first polarizer to polarize environmental light and a dynamic lens that selectively focuses image display light at a controllable virtual distance without affecting the real-world light, ensuring that virtual imagery appears at the correct depth relative to the user's gaze direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a dynamic lens is used to change the focal depth of virtual imagery, then the virtual imagery focus is improved, but the environmental light focus is also affected causing vergence-accommodation mismatch
Solution Approach 1:
The patent segments light into two distinct polarization states (s-polarized and p-polarized). The dynamic lens is configured to affect only one polarization state (s-polarized) while leaving the other (p-polarized) unaffected. This segmentation allows independent control of virtual imagery focus without altering environmental light perception, thereby resolving the vergence-accommodation mismatch.
Solution Approach 2:
The patent applies different optical properties to different polarization states of light. The dynamic lens exhibits polarization-dependent focusing characteristics, providing strong focusing power for s-polarized light (virtual imagery) while having minimal effect on p-polarized light (environmental light). This local quality differentiation enables selective focus control.
2Reliability
If polarization-based selective focusing is implemented, then vergence-accommodation mismatch is reduced, but device complexity increases due to additional polarizing components
Solution Approach 1:
The patent integrates multiple functions into the dynamic lens component. The same dynamic lens simultaneously serves as the focusing element for virtual imagery and the polarization-selective element that differentiates between virtual and environmental light. This multi-functionality reduces the need for separate components and simplifies the overall optical system architecture.
Solution Approach 2:
The patent utilizes changes in the dynamic lens parameters (focal length, optical power) in response to applied voltage to achieve selective focusing. By controlling the electrical parameters of the dynamic lens, the system dynamically adjusts its focusing properties for s-polarized light while maintaining transparency to p-polarized light, enabling adaptive focus control without mechanical complexity.
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 effectively alleviates the vergence-accommodation mismatch by allowing dynamic adjustment of virtual imagery depth without impacting the user's perception of the real environment, reducing discomfort and improving usability during prolonged NED use.
Implementation Method 1
a first polarizer configured to polarize environmental light incident on the first polarizer, such that environmental light passing through the first polarizer toward a user eye has a first polarity
Implementation Method 2
a dynamic lens positioned between the user eye and the image source, the dynamic lens configured to selectively focus incident light having the second polarity without affecting light having the first polarity
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A polarization-based dynamic focuser for a near-eye display includes a first polarizer configured to polarize environmental light incident on the first polarizer, such that environmental light passing through the first polarizer toward a user eye has a first polarity. An image source is positioned between the user eye and the first polarizer. The image source is transparent to the environmental light and is configured to output image display light toward the user eye, at least some of the image display light having a second polarity. A dynamic lens is positioned between the user eye and the image source, and is configured to selectively focus incident light having the second polarity toward the user eye at a controllable virtual distance, where the dynamic lens does not affect incident light having the first polarity.