Broadband Adaptive Lens Assembly for Multi-Depth AR Displays
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Solution Overview
Problem
Conventional augmented reality (AR) and virtual reality (VR) technologies face challenges in providing a comfortable and natural-feeling presentation of virtual image elements among real-world imagery due to mismatches between accommodative and vergence states, leading to user discomfort.
Innovation Solution
The use of an adaptive lens assembly comprising a pair of waveplate lenses with a switchable waveplate between them, which can alter polarization states, and a waveguide assembly to provide variable optical power for simulating multiple depth planes, reducing the need for multiple waveguides and lenses, thereby minimizing thickness, weight, and computational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple waveguides and lenses are used to provide variable optical power for multiple depth planes, then depth perception capability is improved, but device thickness and weight increase
Solution Approach 1:
The patent employs a tunable liquid crystal lens that can dynamically change its focal length and optical power. This single dynamic lens replaces multiple static lenses and waveguides, enabling variable optical power adjustment for different depth planes without increasing device weight. The liquid crystal lens adapts its properties in real-time through electrical control, achieving multi-depth functionality with a single component.
Solution Approach 2:
The tunable liquid crystal lens serves multiple functions simultaneously: it acts as both a focusing element and a depth-plane selector, replacing what would traditionally require separate lenses and waveguides for each depth plane. This multi-functional component reduces the overall number of parts needed in the AR/VR display system.
2Adaptability or versatility
If multiple waveguides and lenses are used to provide variable optical power for multiple depth planes, then depth perception capability is improved, but device thickness increases
Solution Approach 1:
The tunable liquid crystal lens dynamically adjusts its focal length to provide different optical powers for multiple depth planes, eliminating the need for multiple fixed lenses stacked along the optical path. This dynamic adjustment capability allows the system to achieve variable optical power with a single lens element, significantly reducing device thickness.
Solution Approach 2:
The liquid crystal lens changes its optical parameters (focal length, optical power) by altering the liquid crystal molecule orientation through applied electrical fields. This parameter change mechanism allows a single lens to replace multiple lenses with different fixed parameters, reducing the overall thickness of the optical system.
3Adaptability or versatility
If conventional liquid crystal lenses are used, then variable focus capability is achieved, but optical efficiency is lost across certain wavelength ranges
Solution Approach 1:
The patent uses a composite liquid crystal structure combining chiral dopants with specific helical twisting powers that are engineered to work across the visible spectrum. This composite material approach maintains high optical efficiency for both circular polarizations across all wavelengths, unlike conventional single-material liquid crystal lenses that suffer from polarization-dependent efficiency losses.
Solution Approach 2:
The liquid crystal lens employs different liquid crystal materials or doping concentrations in different regions or layers to optimize performance across the wavelength spectrum. By tailoring the local optical properties of the liquid crystal composite, the system maintains high efficiency for both left and right circular polarizations across all visible wavelengths.
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 user comfort by aligning accommodative and vergence cues, providing realistic depth perception with reduced device thickness and weight, while maintaining high optical efficiency across a broad spectrum of wavelengths.
Implementation Method 1
an adaptive lens assembly comprising a pair of waveplate lenses with a switchable waveplate between them, which can alter polarization states
Implementation Method 2
waveplate lenses created in liquid crystal and liquid crystal polymer materials
Data Source
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Figure 3A~3C
AI summary
A display device comprises a waveguide configured to guide light in a lateral direction parallel to an output surface of the waveguide. The waveguide is further configured to outcouple the guided light through the output surface. The display device additionally comprises a broadband adaptive lens assembly configured to incouple and to diffract therethrough the outcoupled light from the waveguide. The broadband adaptive lens assembly comprises a first waveplate lens comprising a liquid crystal (LC) layer arranged such that the waveplate lens has birefringence (Dn) that varies in a radially outward direction from a central region of the first waveplate lens and configured to diffract the outcoupled light at a diffraction efficiency greater than 90% within a wavelength range including at least 450 nm to 630 nm. The broadband adaptive lens assembly is configured to be selectively switched between a plurality of states having different optical powers.