Polarization-Selective Lens Stacks for AR Depth Alignment
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Solution Overview
Problem
Conventional augmented reality (AR) systems struggle to provide a comfortable and natural presentation of virtual image elements amidst real-world imagery due to challenges in simulating realistic depth perception, often causing discomfort through mismatches between accommodative and vergence states in the user's eyes.
Innovation Solution
The use of adaptive lens assemblies with polarization-selective lens stacks, comprising birefringent and isotropic lenses, and switchable waveplates, allow for variable optical power to modify wavefront divergence, providing virtual depth planes and correcting for distortions, thereby aligning accommodative and vergence cues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional AR systems present virtual image elements without modifying wavefront divergence, then the system structure remains simple, but the user experiences discomfort due to mismatches between accommodative and vergence states
Solution Approach 1:
The patent implements dynamic optical power adjustment through adaptive lens assemblies that can change their focusing properties in real-time. The system uses variable optical power elements that can be dynamically controlled to modify wavefront divergence, allowing the optical system to adapt to different viewing conditions and align accommodative-vergence cues, thereby resolving the technical contradiction between user comfort and system complexity.
Solution Approach 2:
The patent changes optical parameters by introducing elements with variable optical power that can modify wavefront divergence. By adjusting parameters such as refractive index, lens curvature, and optical power dynamically, the system creates multiple virtual depth planes and aligns accommodative-vergence cues, improving user comfort while managing system complexity through controlled parameter modification.
2Adaptability or versatility
If multiple waveguides are used to provide different virtual depth planes, then depth perception is improved, but the device complexity and computational power requirements increase
Solution Approach 1:
The patent implements a single waveguide structure that performs multiple functions by combining it with adaptive lens assemblies capable of variable optical power. This universal approach allows one waveguide to provide multiple virtual depth planes through dynamic lens adjustment, eliminating the need for multiple separate waveguides and reducing overall system complexity while maintaining adaptability.
Solution Approach 2:
The patent uses dynamic lens elements with variable optical power that can be adjusted in real-time to create different virtual depth planes within a single waveguide system. This dynamic capability allows the system to provide multiple depth planes without requiring multiple static waveguides, thereby reducing device complexity while maintaining versatility.
3Ease of operation
If adaptive lens assemblies with variable optical power are implemented, then wavefront divergence is corrected and accommodative-vergence alignment is achieved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent implements feedback mechanisms that use eye tracking and optical sensing to monitor the user's accommodative and vergence states in real-time. This feedback information is used to dynamically adjust the optical power of lens elements, allowing the system to achieve and maintain accommodative-vergence alignment adaptively, thereby reducing the stringency of fixed manufacturing precision requirements.
Solution Approach 2:
The patent uses variable optical power elements whose parameters can be adjusted dynamically after manufacturing. By allowing post-manufacturing parameter adjustment and real-time optimization, the system can achieve high precision accommodative-vergence alignment without requiring extremely tight manufacturing tolerances, thus resolving the contradiction between alignment quality and manufacturing precision requirements.
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 approach enhances the realism and comfort of AR experiences by aligning accommodative and vergence states, reducing the need for multiple waveguides and minimizing computational power requirements.
Implementation Method 1
The birefringent lens has an optical axis and a birefringence (Δn) and is configured to exert a first optical power to light having a polarization direction parallel to the optical axis. The birefringent lens is also configured to exert a second optical power to light having a polarization direction perpendicular to the optical axis.
Implementation Method 2
The switchable waveplate is configured to rotate a polarization direction of incident light by 0° or by 90° in response to an applied voltage
Implementation Method 3
allow for variable optical power to modify wavefront divergence, providing virtual depth planes
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
The present disclosure relates to display systems and, more particularly, to augmented reality display systems. In one aspect, an adaptive lens assembly includes a lens stack configured to exert polarization-dependent optical power to linearly polarized light. The lens stack includes a birefringent lens and an isotropic lens contacting each other to form a conformal interface therebetween. The adaptive lens assembly is configured to be selectively switched between a plurality of states having different optical powers.