AR Device Reflective Polarizer Variable Focus Lens
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Solution Overview
Problem
Augmented reality devices cause dizziness due to a vergence-accommodation conflict (VAC) as the focus position of virtual images and real objects differ, and existing solutions with multiple lenses or polarizers are cumbersome and difficult to implement effectively.
Innovation Solution
An augmented reality device incorporating a wire grid polarizer and a polarization selective variable focus lens with electrically variable refractive power, which separates and adjusts the focus of virtual images by reflecting one polarization and transmitting another, allowing for easier polarization separation and focus adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple lenses and polarizers are used to adjust focus and separate polarization, then the focus adjustment capability is improved, but the device size and complexity increase
Solution Approach 1:
The variable focus lens is designed to perform both focus adjustment and polarization separation functions simultaneously. By incorporating polarization-selective variable focus capability, a single optical element achieves what previously required multiple separate components, thereby reducing device complexity while maintaining adaptability
Solution Approach 2:
The patent utilizes electrically controllable variable focus lenses that can dynamically change their refractive power and focal length by adjusting electrical parameters (voltage). This allows the lens to adapt between different focus states and polarization conditions without requiring mechanical replacement of optical elements, reducing overall system complexity
2Adaptability or versatility
If multiple lenses and polarizers are used to adjust focus, then the focus adjustment capability is improved, but the device size becomes large
Solution Approach 1:
The variable focus lens integrates multiple optical functions into a single compact element, eliminating the need for separate polarizers and multiple lenses. This consolidation significantly reduces the overall device volume while preserving focus adjustment capability
Solution Approach 2:
The patent merges the functions of polarization separation and focus adjustment into a single integrated optical system. By combining these previously separate functions into one variable focus lens assembly, the device achieves compact dimensions suitable for wearable applications
3Adaptability or versatility
If a polarizer and variable focus lens are used to separate polarization, then the polarization separation is achieved, but it becomes difficult to separate the polarization of real object and virtual image
Solution Approach 1:
The variable focus lens exhibits polarization-selective properties where different polarization components experience different refractive indices and focal lengths. This local polarization-dependent optical response enables automatic separation of real object and virtual image polarizations based on their distinct optical paths, simplifying the separation process
Solution Approach 2:
The system utilizes the inherent polarization feedback mechanism where the variable focus lens responds differently to s-polarized and p-polarized light. This creates natural optical feedback that separates the polarizations of real and virtual images through their different focal positions, making separation more straightforward
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 configuration reduces user dizziness by aligning the focus of virtual images with real objects, enhancing the usability of augmented reality devices without increasing their size or complexity.
Implementation Method 1
a reflective polarizer provided on the side of the second surface of the optical coupler and configured to reflect first polarized light with a first polarization and transmit second polarized light with a second polarization different from the first polarization
Implementation Method 2
a polarization selective variable focus lens provided in a traveling path of the first polarized light that has been reflected by the reflective polarizer, the polarization selective variable focus lens having variable refractive power with respect to the first polarized light
Implementation Method 3
an optical coupler including a first surface through which the first image is input and a second surface opposite the first surface, the optical coupler being configured to output light that is input through the first surface to the second surface
Data Source
AI summary
Provided is an augmented reality device including a display element configured to generate a first image, an optical coupler including a first surface through which the first image is input and a second surface opposite the first surface and configured to output light that is input through the first surface to the second surface and output light that is input through the second surface to the first surface, a reflective polarizer provided on the side of the second surface of the optical coupler and configured to reflect light with a first polarization and transmit light with a second polarization different from the first polarization, and a polarization selective variable focus lens provided in a traveling path of the light with the first polarization reflected by the reflective polarizer and having variable refractive power with respect to the light with the first polarization.