Liquid crystal lens array for a 3D endoscope

Hassanfiroozi, Amir; Jen, Tai-Hsiang; Huang, Yi‐Pai; Shieh, Han–Ping D.

doi:10.1117/2.1201405.005419

Cited by 4 publications

(3 citation statements)

References 16 publications

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“…Microlens arrays are used for a wide range of applications. − Individual lenses have convex or concave spherical cap shapes where the optical path n ( r ) · d ( r ) varies due to the thickness variation d ( r ), while the refractive index is constant. Fabricating such arrays usually requires complex processes such as photoresist thermal reflow, , photolithography, plasmonic photopatterning, − nanoimprinting, inkjet printing, and direct laser writing .…”

Section: Introductionmentioning

confidence: 99%

Converging Microlens Array Using Nematic Liquid Crystals Doped with Chiral Nanoparticles

Perera

Nemati

Mann

et al. 2021

ACS Appl. Mater. Interfaces

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Nematic liquid crystals of achiral molecules or racemic mixtures of chiral ones form flat films when suspended in submillimeter size grids and submerged under water. Recently, it has been shown (Popov et al., 2017) that films of nematic liquid crystals doped with chiral molecules adopt biconvex lens shapes underwater. The curved shape together with degenerate planar anchoring leads to a radial variation of the optical axis along the plane of the film, providing a Pancharatnam–Berry-type phase lens that modifies geometric optical imaging. Here, we describe nematic liquid crystal microlenses formed by the addition of chiral nanoparticles. It is found that the helical twisting power of the nanoparticles, the key factor to form the lens, is about 400 μm–1, greater than that of the strongest molecular chiral dopants. We demonstrate imaging capabilities and measure the shape as well as the focal length of the chiral nanoparticle-doped liquid crystal lens. We show that measuring the shape of the lens allows one to calculate the helical pitch of the chiral nematic liquid crystal and thus determine the helical twisting power of the chiral ligand-capped nanoparticles. Such measurements require the use of only nanograms of chiral nanoparticles, which is 3 orders of magnitude less than that required by conventional techniques. Since NPs are sensitive to external stimuli such as light and electric and magnetic fields, the use of chiral NPs may allow the achievement of tunable optical properties for such microlens arrays.

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Section: Introductionmentioning

confidence: 99%

Converging Microlens Array Using Nematic Liquid Crystals Doped with Chiral Nanoparticles

Perera

Nemati

Mann

et al. 2021

ACS Appl. Mater. Interfaces

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“…In order to acquire better lens quality, a 20nm Nb2O5 high resistance (Hi-R) layer was coated on the top of aluminum electrode to smooth the electric field on the boundary electrodes. This layer could not only decrease the driving voltage but simplify the driving method [9,10]. where f and r represent the effective focal length and the radius of lens aperture.…”

Section: Optical Componentsmentioning

confidence: 99%

10‐4: Stereoscopic / Light Field Hybrid Head‐mounted Display by Using Time‐multiplexing Method

Wang

Chou

Yee

et al. 2018

Symp Digest of Tech Papers

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Stereoscopic / Light Field Hybrid Head-mounted Display was proposed to avoid accommodation -convergence conflict and improve the resolution of light field image. This new system generate images in LF and stereoscopic mode, further producing hybrid images by the visual persistence of human eyes. To build a mechanism for the time-multiplexing of the polarized light, we designed and fabricated a micro-lens array with the liquid crystal material. Specifically, with the function of TN cell and LC MLA, Hybrid HMD could time-multiplex two images in flicker-free frame rate. In our results, the resolution of hybrid image can be significantly enhanced from 5.5 ppd to 10 ppd in horizontal direction and 6.2 ppd to 15.9 ppd in vertical direction. Author Keywordsvirtual reality, light field, head-mounted display, micro-lens array 1.

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“…Since first discovery of transparent conductive films such as Indium Tin Oxide (ITO) [110,111] and due to its high conductivity and transparency in the visible light, it has become an attractive material used in several fields such as electro-optic devices, liquid crystal displays, and photovoltaics among many others [112][113][114]. Depending on the application, ITO can be deposited by different methods such as thermal evaporation, spray pyrolysis, pulsed laser deposition, screen printing techniques, and the most common method, and the preferred in the industry, sputtering [111,[114][115][116][117][118][119][120][121][122][123][124][125][126][127][128].…”

Section: Optimization Of Conductive Transparent Layer With Low Resist...mentioning

confidence: 99%

Contribution to liquid lens technology

Ahmadi Zeidabadi

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The interest on microfluidic systems based on electrowetting-on-dielectric (EWOD) and the miniaturization of such integrated devices, has increased significantly mainly due to the advent of mass market applications such as lab-on-chip, liquid lenses and reflective displays. The main objective of this work focuses on the scientific and technological challenges that the fabrication and optimization of liquid lens faces. Those are mainly related to the materials used and their associated fabrication techniques, in order to have stable devices with high performance for long term functionality. The work reported here contributes the research to reduce the actuation voltage and to increase stability and reliability of electrowetting devices such as liquid lenses at laboratory scale. We address various aspects related to liquid lenses: (a), improvement of the hydrophobic layer deposition process leading contact angle recovery enhancement, (b) investigation of the dielectric materials and deposition techniques to reduce the required applied voltage (c) specific design of electrodes for 2D movement of the liquid lens, and (d) investigation of nonaqueous liquids to improve the dynamic behavior and long term cycling functionality. (e) An attempt is made to develop behavioral models that can explain EWOD phenomena with an electronic circuit software. El interés en los sistemas microfluídicos basados en electrohumectación sobre un dieléctrico (electrowetting-on-dielectric, EWOD) y la miniaturización de dichos dispositivos integrados, ha aumentado significativamente, principalmente debido a la llegada de aplicaciones del mercado de masas, como lab-on-chip, lentes líquidas y pantallas reflectantes. El objetivo principal de este trabajo se centra en los retos científicos y tecnológicos de la fabricación y la optimización de una lente líquida. Principalmente, los que están relacionadas con los materiales utilizados y sus técnicas de fabricación asociadas, con el fin de tener dispositivos estables con un alto rendimiento para la funcionalidad a largo plazo. Este trabajo describe la investigación llevada a cabo para reducir la tensión de accionamiento y para aumentar la estabilidad y la fiabilidad de los dispositivos EWOD, tales como lentes líquidas, a escala de laboratorio. Los principales aspectos relacionados con lentes líquidas trabajados en esta tesis son los siguientes: (a) la mejora del proceso de depósito de la capa hidrofóbica que determina el ángulo de contacto y mejora su recuperación, (b) la investigación de los materiales dieléctricos y técnicas de depósito para reducir la tensión aplicada, (c) el diseño específico de electrodos para el movimiento en 2D de la lente líquida, y (d) la investigación de los líquidos no acuosos para mejorar el comportamiento dinámico y la funcionalidad en frecuencia a largo plazo. (e) También se ha iniciado el desarrollo de modelos de comportamiento que puedan explicar fenómenos EWOD con un software de circuitos electrónicos.

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Liquid crystal lens array for a 3D endoscope

Abstract: A plano-convex electrode for a hexagonal LC lens array combines a small inactive region, 30 m cell gap, short focal length, and operates at low applied voltage.

Cited by 4 publications

References 16 publications

Converging Microlens Array Using Nematic Liquid Crystals Doped with Chiral Nanoparticles

Converging Microlens Array Using Nematic Liquid Crystals Doped with Chiral Nanoparticles

10‐4: Stereoscopic / Light Field Hybrid Head‐mounted Display by Using Time‐multiplexing Method

Contribution to liquid lens technology

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