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Feng W, Ye M. Refractive Fresnel liquid crystal lenses driven by two voltages. OPTICS EXPRESS 2024; 32:662-676. [PMID: 38175090 DOI: 10.1364/oe.512132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Accepted: 12/10/2023] [Indexed: 01/05/2024]
Abstract
We propose and demonstrate a high-performance refractive Fresnel liquid crystal (LC) lens with a simple electrode design. The interconnected circular electrodes enable the creation of a parabolic voltage distribution within each Fresnel zone using only two driving voltages. By controlling these voltages within the linear response region of LC material, the desired parabolic phase profile can be achieved. We provide a detailed discussion on the electrode structure design methodology and operating principles of the lens. In our experiments, we constructed a four-zone Fresnel LC lens with a total aperture of 8 mm. The results show that the optical power of the lens can be continuously adjusted from -1.30 D to +1.33 D. Throughout the process of electrically tuning the optical power, the phase distribution within each Fresnel zone maintains a parabolic profile. These results demonstrate the high-performance of the proposed Fresnel LC lens.
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Bosch M, Shcherbakov MR, Won K, Lee HS, Kim Y, Shvets G. Electrically Actuated Varifocal Lens Based on Liquid-Crystal-Embedded Dielectric Metasurfaces. NANO LETTERS 2021; 21:3849-3856. [PMID: 33900774 DOI: 10.1021/acs.nanolett.1c00356] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Compact varifocal lenses are essential to various imaging and vision technologies. However, existing varifocal elements typically rely on mechanically actuated systems with limited tuning speeds and scalability. Here, an ultrathin electrically controlled varifocal lens based on a liquid crystal (LC) encapsulated dielectric metasurface is demonstrated. Enabled by the field-dependent LC anisotropy, applying a voltage bias across the LC cell modifies the local phase response of the silicon meta-atoms, in turn modifying the metalens focal length. In a numerical implementation, a voltage-actuated metalens with continuous zoom and up to 20% total focal shift is demonstrated. The LC-based metalens concept is experimentally verified through the design and fabrication of a bifocal metalens that facilitates high-contrast switching between two discrete focal lengths upon application of a 9.8 Vpp voltage bias. Owing to their ultrathin thickness and adaptable design, LC-driven dielectric metasurfaces open new opportunities for compact varifocal lensing in a diversity of modern imaging applications.
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Affiliation(s)
- Melissa Bosch
- Department of Physics, Cornell University, Ithaca, New York 14853, United States
| | - Maxim R Shcherbakov
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States
| | - Kanghee Won
- Samsung Advanced Institute of Technology (SAIT), Samsung Electronics, Co. Ltd., Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Hong-Seok Lee
- Samsung Advanced Institute of Technology (SAIT), Samsung Electronics, Co. Ltd., Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Young Kim
- Samsung Advanced Institute of Technology (SAIT), Samsung Electronics, Co. Ltd., Suwon-si, Gyeonggi-do 16678, Republic of Korea
| | - Gennady Shvets
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States
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Morris R, Jones C, Nagaraj M. Liquid Crystal Devices for Beam Steering Applications. MICROMACHINES 2021; 12:247. [PMID: 33671001 PMCID: PMC7997246 DOI: 10.3390/mi12030247] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 02/22/2021] [Accepted: 02/23/2021] [Indexed: 11/17/2022]
Abstract
Liquid crystals are valuable materials for applications in beam steering devices. In this paper, an overview of the use of liquid crystals in the field of adaptive optics specifically for beam steering and lensing devices is presented. The paper introduces the properties of liquid crystals that have made them useful in this field followed by a more detailed discussion of specific liquid crystal devices that act as switchable optical components of refractive and diffractive types. The relative advantages and disadvantages of the different devices and techniques are summarised.
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Affiliation(s)
| | | | - Mamatha Nagaraj
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK; (R.M.); (C.J.)
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Ahmed R, Butt H. Strain-Multiplex Metalens Array for Tunable Focusing and Imaging. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:2003394. [PMID: 33643805 PMCID: PMC7887606 DOI: 10.1002/advs.202003394] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 11/01/2020] [Indexed: 05/08/2023]
Abstract
Metalenses on a flexible template are engineered metal-dielectric interfaces that improve conventional imaging system and offer dynamic focusing and zooming capabilities by controlling the focal length and bandwidth through a mechanical or external stretch. However, realizing large-scale and cost-effective flexible metalenses with high yields in a strain-multiplex fashion remains as a great challenge. Here, single-pulsed, maskless light interference and imprinting technique is utilized to fabricate reconfigurable, flexible metalenses on a large-scale and demonstrate its strain-multiplex tunable focusing. Experiments, in accordance with the theory, show that applied stretch on the flexible-template reconfigurable diffractive metalenses (FDMLs) accurately mapped focused wavefront, bandwidth, and focal length. The surface relief metastructures consisted of metal-coated hemispherical cavities in a hexagonal close-packed arrangement to enhance tunable focal length, numerical aperture, and fill factor, FF ≈ 100% through normal and angular light illumination with external stretch. The strain-multiplex of FDMLs approach lays the foundation of a new class of large-scale, cost-effective metalens offering tunable light focusing and imaging.
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Affiliation(s)
- Rajib Ahmed
- School of EngineeringUniversity of BirminghamBirminghamB15 2TTUK
- Stanford School of MedicinePalo AltoCA94304United States
| | - Haider Butt
- Department of Mechanical EngineeringKhalifa UniversityAbu DhabiP.O. 127788UAE
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Hsu CJ, Singh BP, Antony M, Selvaraj P, Manohar R, Huang CY. Liquid crystal lens with doping of rutile titanium dioxide nanoparticles. OPTICS EXPRESS 2020; 28:22856-22866. [PMID: 32752539 DOI: 10.1364/oe.401028] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 07/08/2020] [Indexed: 06/11/2023]
Abstract
A 4 mm-aperture hole-patterned liquid crystal (LC) lens has been fabricated using a LC mixture, which consisted of rutile titanium dioxide (TiO2) nanoparticles (NPs) and nematic LC E7, for the first time. The TiO2 NP dopant improves the addressing and operation voltages of the LC lens significantly because it strengthens the electric field surrounding the TiO2 NP and increases the capacitance of lens cell. Unlike the doping of common colloidal NPs, that of rutile TiO2 NPs increases the phase transition temperature and birefringence of the LC mixture, thereby helping enhance the lens power of LC lens. In comparison with a pure LC lens, the TiO2 NP-doped one has approximately 50% lower operation voltage because of the strengthened electric field around the NPs and has roughly 2.8 times faster response time because of the decreased rotational viscosity of the LC mixture and the increased interaction between the LC molecules by the NP dopants. Notably, the doping of rutile TiO2 NPs improves the operation voltage, tunable focusing capability, and response time of LC lens simultaneously. Meanwhile, this method does not degrade the focusing and lens qualities. The imaging performances of TiO2 NP-doped LC lens at various voltages are demonstrated practically by tunable focusing on three objectives at different positions. These results introduce NP in the application of LC lenses.
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Wang JH, Tang WP, Li LY, Xiao L, Zhou X, Wang QH. Hybrid driving variable-focus optofluidic lens. OPTICS EXPRESS 2019; 27:35203-35215. [PMID: 31878693 DOI: 10.1364/oe.27.035203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 11/06/2019] [Indexed: 06/10/2023]
Abstract
Conventional optofluidic lens usually has only one interface, which means that the zoom range is small, and the ability to correct aberrations is poor. In this paper, we propose a hybrid driving variable-focus optofluidic lens. It has one water-oil interface shifted by an applied voltage and one tunable Polydimethylsiloxane (PDMS) lens deformed by pumping liquid in or out of the cavity. The proposed lens combines the advantages of electrowetting lens and mechanical lens. Therefore, it can provide a large focal length tuning range with good image quality. The shortest positive and negative focal length are ∼6.02 mm and ∼-11.15 mm, respectively. The maximum resolution of our liquid lens can be reached 18 lp/mm. We also designed and fabricated a zoom system using the hybrid driving variable-focus optofluidic lens. In the experiment, the zoom range of the system is 14 mm∼30 mm and the zoom ratio is ∼2.14× without any mechanical moving parts. Its applications for zoom telescope system and zoom microscope and so on are foreseeable.
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Dou H, Chu F, Guo YQ, Tian LL, Wang QH, Sun YB. Large aperture liquid crystal lens array using a composited alignment layer. OPTICS EXPRESS 2018; 26:9254-9262. [PMID: 29715879 DOI: 10.1364/oe.26.009254] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 03/22/2018] [Indexed: 06/08/2023]
Abstract
A liquid crystal (LC) lens array with high light control power and a large aperture using a composited alignment layer is proposed. In our design, the alignment layer is not only used for getting a uniform arrangement of LC molecule, but also for getting a lens-like refractive index distribution in the LC layer when a voltage is applied. Through simple technology processes, a tunable focal length LC lens array with a millimeter scale diameter can be achieved. Furthermore, the maximum phase difference of the proposed LC lens array can achieve 105.38π. So, the proposed LC lens array has a high light control power.
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She A, Zhang S, Shian S, Clarke DR, Capasso F. Adaptive metalenses with simultaneous electrical control of focal length, astigmatism, and shift. SCIENCE ADVANCES 2018; 4:eaap9957. [PMID: 29507880 PMCID: PMC5834009 DOI: 10.1126/sciadv.aap9957] [Citation(s) in RCA: 111] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 01/22/2018] [Indexed: 05/20/2023]
Abstract
Focal adjustment and zooming are universal features of cameras and advanced optical systems. Such tuning is usually performed longitudinally along the optical axis by mechanical or electrical control of focal length. However, the recent advent of ultrathin planar lenses based on metasurfaces (metalenses), which opens the door to future drastic miniaturization of mobile devices such as cell phones and wearable displays, mandates fundamentally different forms of tuning based on lateral motion rather than longitudinal motion. Theory shows that the strain field of a metalens substrate can be directly mapped into the outgoing optical wavefront to achieve large diffraction-limited focal length tuning and control of aberrations. We demonstrate electrically tunable large-area metalenses controlled by artificial muscles capable of simultaneously performing focal length tuning (>100%) as well as on-the-fly astigmatism and image shift corrections, which until now were only possible in electron optics. The device thickness is only 30 μm. Our results demonstrate the possibility of future optical microscopes that fully operate electronically, as well as compact optical systems that use the principles of adaptive optics to correct many orders of aberrations simultaneously.
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Shang X, Meeus L, Cuypers D, De Smet H. Fast switching cholesteric liquid crystal optical beam deflector with polarization independence. Sci Rep 2017; 7:6492. [PMID: 28747672 PMCID: PMC5529461 DOI: 10.1038/s41598-017-06944-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 06/20/2017] [Indexed: 11/09/2022] Open
Abstract
Optical beam deflectors based on the combination of cholesteric liquid crystals and polymer micro gratings are reported. Dual frequency cholesteric liquid crystal (DFCh-LC) is adopted to accelerate the switching from the homeotropic state back to the planar state. Polarization independent beam steering components are realized whose transmission versus the polarizing angle only varies 4.4% and 2.6% for the planar state and the homeotropic state, respectively. A response time of 451 ms is achieved for DFCh-LC-grating beam deflectors, which is fast compared to other nematic LC beam steerers with similar LC thickness.
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Affiliation(s)
- Xiaobing Shang
- Ghent University and imec, Department of Electronics and Information Systems, Ghent, 9052, Belgium
| | - Laurens Meeus
- Ghent University, Department of Telecommunications and Information Processing, Ghent, 9000, Belgium
| | - Dieter Cuypers
- Ghent University and imec, Department of Electronics and Information Systems, Ghent, 9052, Belgium
| | - Herbert De Smet
- Ghent University and imec, Department of Electronics and Information Systems, Ghent, 9052, Belgium.
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Hsu CJ, Jhang JJ, Huang CY. Large aperture liquid crystal lens with an imbedded floating ring electrode. OPTICS EXPRESS 2016; 24:16722-16731. [PMID: 27464126 DOI: 10.1364/oe.24.016722] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We propose a hole-patterned large aperture (LA) liquid crystal (LC) lens with a diameter of 6 mm. In our design, a floating ring electrode is embedded into the interface between the dielectric layer and the LC layer. This structure increases the electric field strength around the floating ring electrode located near the aperture center and assists in distributing the fringing electric field throughout the LC layer. Therefore, the thick dielectric layer used in the conventional hole-patterned LA LC lens can be effectively decreased. Consequently, the proposed LA LC lens has low operation voltage, large lens power, and introduces a low wavefront error of approximately 0.07 λ.
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Hui L, Fan P, Yuntao W, Yanduo Z, Xiaolin X. Depth map sensor based on optical doped lens with multi-walled carbon nanotubes of liquid crystal. APPLIED OPTICS 2016; 55:140-147. [PMID: 26835633 DOI: 10.1364/ao.55.000140] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In this paper, we present a novel design concept for determining the depth map of three-dimensional (3D) scenes based on an electrically controlled liquid crystal (LC) lens. The advantages of the proposed method are that it does not need any mechanical movements and a large amount of computations to acquire a depth map of a 3D scene in a relatively short amount of time. The tunable-focus LC lens doped with multi-walled carbon nanotubes is to become a key optical component for determining a depth map system. Sequenced two-dimensional images of slightly different perspectives are recorded in a short time, and the depth map of the 3D scene, according to a proposed depth estimation method and a focusing evaluation function, can be acquired in a simple way. This new method to acquire a depth map based on a doped LC lens maximizes the use of the proposed LC lens. The proposed system is novel in its compact, simple, and fast features, so we believe the proposed method can open a new creative dimension in image analysis and imaging systems and can also overcome the limitations of the conventional imaging mode.
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Li L, Bryant D, Van Heugten T, Bos PJ. Speed, optical power, and off-axis imaging improvement of refractive liquid crystal lenses. APPLIED OPTICS 2014; 53:1124-1131. [PMID: 24663311 DOI: 10.1364/ao.53.001124] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 01/14/2014] [Indexed: 06/03/2023]
Abstract
Two design approaches (multicell and addition of phase resets in single cell) are introduced to optimize the performances of tunable refractive liquid crystal lenses, including improvements on the switching speed, optical power, and the off-axis, wide-angle imaging performance. Key parameters and advantages for each method are discussed, and their effects on the performance are demonstrated in detail with numerical calculations.
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Li L, Bryant D, Van Heugten T, Bos PJ. Near-diffraction-limited and low-haze electro-optical tunable liquid crystal lens with floating electrodes. OPTICS EXPRESS 2013; 21:8371-8381. [PMID: 23571926 DOI: 10.1364/oe.21.008371] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A near-diffraction-limited, low-haze and tunable liquid crystal (LC) lens is presented. Building on an understanding of the key factors that have limited the performance of lenses based on liquid crystals, we show a simple design whose optical quality is similar to a high quality glass lens. It uses 'floating' electrodes to provide a smooth, controllable applied potential profile across the aperture to manage the phase profile.
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Affiliation(s)
- Liwei Li
- Liquid Crystal Institute, Kent State University, Kent, OH 44240, USA
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