scholarly journals Recent Advances in Adaptive Liquid Crystal Lenses

Crystals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 272 ◽  
Author(s):  
José Francisco Algorri ◽  
Dimitrios C. Zografopoulos ◽  
Virginia Urruchi ◽  
José Manuel Sánchez-Pena
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Focal Length ◽  
Research Field ◽  
Performance Characteristics ◽  
External Stimulus ◽  
Future Prospects ◽  
Advantages And Disadvantages ◽  
Recent Advances ◽  
Active Research

An adaptive-focus lens is a device that is capable of tuning its focal length by means of an external stimulus. Numerous techniques for the demonstration of such devices have been reported thus far. Moving beyond traditional solutions, several new approaches have been proposed in recent years based on the use of liquid crystals, which can have a great impact in emerging applications. This work focuses on the recent advances in liquid crystal lenses with diameters larger than 1 mm. Recent demonstrations and their performance characteristics are reviewed, discussing the advantages and disadvantages of the reported technologies and identifying the challenges and future prospects in the active research field of adaptive-focus liquid crystal (LC) lenses.

scholarly journals Liquid Crystal Devices for Beam Steering Applications

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 247
Author(s):  
Rowan Morris ◽  
Cliff Jones ◽  
Mamatha Nagaraj
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Adaptive Optics ◽  
Beam Steering ◽  
Optical Components ◽  
Advantages And Disadvantages ◽  
Liquid Crystal Devices

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.

Smart Glass and Its Potential in Energy Savings

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Kaufui V. Wong ◽  
Richard Chan
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Energy Demand ◽  
Energy Savings ◽  
Suspended Particle ◽  
Light Transmittance ◽  
Voltage Source ◽  
Glass Technology ◽  
Ion Conductor ◽  
Advantages And Disadvantages

Smart glass is such that its properties may be changed by application of a potential across it. The change in properties may be engineered to alter the amount of heat energy that can penetrate the glass which provides heating and cooling design options. Therein lies its potential in energy savings. Smart glass may be classified into three types: electrochromic, suspended particle, and polymer dispersed liquid crystal (PDLC). Each of these types has their own mechanisms, advantages, and disadvantages. Electrochromic smart glass is the most popular, currently it utilizes an electrochromic film with an ion storage layer and ion conductor placed between two transparent plates. The electrochromic film is usually made of tungsten oxide, owing to the electrochromic nature of transition metals. An electric potential initiates a redox reaction of the electrochromic film transitioning the color and the transparency of the smart glass. Suspended particle smart glass has needle shaped particles suspended within an organic gel placed between two electrodes. In its off state, the particles are randomly dispersed and have a low light transmittance. Once a voltage is applied, the needle particles will orient themselves to allow for light to pass through. PDLC smart glass works similarly to the suspended particle variety. However, in PDLC smart glass, the central layer is a liquid crystal placed within a polymer matrix between electrodes. Similar in behavior to the suspended particles, in the off position the liquid crystals are randomly dispersed and have low transmittance. With the application of a voltage, the liquid crystals orient themselves, thereby allowing for the transmittance of light. These different smart glasses have many different applications, but with one hindrance. The requirement of a voltage source is a major disadvantage which greatly complicates the overall installation and manufacturing processes. However, the integration of photovoltaic (PV) devices into smart glass technology has provided one solution. Photovoltaic films attached in the smart glass will provide the necessary voltage source. The photovoltaic film may even be designed to produce more voltage than needed. The use a photovoltaic smart glass system provides significant cost savings in regards to heating, cooling, lighting, and overall energy bills. Smart glass represents a technology with a great deal of potential to reduce energy demand. Action steps have been identified to propagate the popular use of smart glass.

scholarly journals A Survey on Text-based Modeling in Model Evolution and Management

2019 ◽  
Vol 63 (1) ◽  
pp. 51-65
Author(s):  
Ferenc A. Somogyi ◽  
Mark Asztalos
Keyword(s):  
Source Code ◽  
Research Area ◽  
Research Field ◽  
Future Research ◽  
Model Evolution ◽  
Model Driven ◽  
Advantages And Disadvantages ◽  
Model Differencing ◽  
Graphical Notations ◽  
Active Research

Model-driven software engineering methodologies like model-driven engineering aim to improve the productivity of software development by using graph-based models as the main artifacts during development, and generating the source code from these models. The models are usually displayed and edited using a graphical notation. However, they can also be described using a textual notation. This has some advantages and disadvantages compared to the graphical approach. For example, while editing the model, we can better focus on the details instead of a broad overview. Similarly to source code, models evolve rapidly during development. Handling and managing the evolution of models is an important task in model-driven methodologies and is an active research area today. However, there exist few research on text-based modeling approaches, compared to graph-based ones. This paper introduces the text-based modeling research field based on existing literature, and presents the state-of-the-art of the field related to model evolution and management. Our goal is to identify challenges and directions for future research in this field. The main topics covered are model differencing and merging, and the synchronization of the textual and graphical notations.

scholarly journals Liquid Crystal Optics and Physics: Recent Advances and Prospects

Crystals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 670 ◽  
Author(s):  
Chun-Ta Wang ◽  
Chan-Shan Yang ◽  
Qi Guo
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Mobile Phones ◽  
Daily Life ◽  
Crystal Optics ◽  
Recent Advances

For more than 100 years, liquid crystals (LCs) have been extensively investigated and LC displays now are becoming ubiquitous in our daily life, from TVs, mobile phones to indoor/outdoor signage [...]

scholarly journals Recent Advances in Brillouin Optical Correlation-Domain Reflectometry

2018 ◽  
Vol 8 (10) ◽  
pp. 1845 ◽  
Author(s):  
Yosuke Mizuno ◽  
Heeyoung Lee ◽  
Kentaro Nakamura
Keyword(s):  
Cost Efficiency ◽  
High Speed ◽  
High Spatial Resolution ◽  
Brillouin Scattering ◽  
Fundamental Principle ◽  
Future Prospects ◽  
Optical Correlation ◽  
Advantages And Disadvantages ◽  
Recent Advances ◽  
Nominal Resolution

Distributed fiber-optic sensing based on Brillouin scattering has been extensively studied and many configurations have been developed so far. In this paper, we review the recent advances in Brillouin optical correlation-domain reflectometry (BOCDR), which is known as a unique technique with intrinsic single-end accessibility, high spatial resolution, and cost efficiency. We briefly discuss the advantages and disadvantages of BOCDR over other Brillouin-based distributed sensing techniques, and present the fundamental principle and properties of BOCDR with some special schemes for enhancing the performance. We also describe the recent development of a high-speed configuration of BOCDR (slope-assisted BOCDR), which offers a beyond-nominal-resolution detectability. The paper is summarized with some future prospects.

scholarly journals Electrically Tunable Fresnel Lens in Twisted-Nematic Liquid Crystals Fabricated by a Sagnac Interferometer

Polymers ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1448 ◽  
Author(s):  
Bing-Yau Huang ◽  
Tsung-Hsien Lin ◽  
Tian-Yi Jhuang ◽  
Chie-Tong Kuo
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Azo Dye ◽  
Focal Length ◽  
Fresnel Lens ◽  
Sagnac Interferometer ◽  
Alignment Effect ◽  
Twisted Nematic ◽  
Linearly Polarized ◽  
Photo Alignment

This paper presents an electrically tunable Fresnel lens in a twisted nematic liquid crystal cell fabricated by using a Sagnac interferometer. When the Fresnel-patterned green beam, formed by the Sagnac interferometer, is irradiated on the azo-dye doped liquid crystal mixture, the azo-dye molecules undergo trans–cis photoisomerization and then generate the photo-alignment effect in the bright (odd) zones. The director of the liquid crystal molecules in the odd zones reorients the direction perpendicular to the polarization direction of the linearly polarized green beam. The various structures of liquid crystals in the odd and even zones will result in a phase difference and thus, a Fresnel lens can be generated. The experimental results show that the proposed Fresnel lens has a high diffraction efficiency of 31.5% under an applied alternating-currents (AC) voltage. The focal length of the Fresnel lens can also be tuned by thermally erasing the photo-alignment effect of the azo dyes and rewriting by a different Fresnel-like pattern.

scholarly journals Perspectives in Liquid-Crystal-Aided Nanotechnology and Nanoscience

2019 ◽  
Vol 9 (12) ◽  
pp. 2512 ◽  
Author(s):  
Yuan Shen ◽  
Ingo Dierking
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Magnetic Particles ◽  
Research Field ◽  
Lyotropic Liquid Crystal ◽  
Significant Extent ◽  
Functional Nanoparticles ◽  
Optical Shutter ◽  
Different Shapes ◽  
Novel Applications

The research field of liquid crystals and their applications is recently changing from being largely focused on display applications and optical shutter elements in various fields, to quite novel and diverse applications in the area of nanotechnology and nanoscience. Functional nanoparticles have recently been used to a significant extent to modify the physical properties of liquid crystals by the addition of ferroelectric and magnetic particles of different shapes, such as arbitrary and spherical, rods, wires and discs. Also, particles influencing optical properties are increasingly popular, such as quantum dots, plasmonic, semiconductors and metamaterials. The self-organization of liquid crystals is exploited to order templates and orient nanoparticles. Similarly, nanoparticles such as rods, nanotubes and graphene oxide are shown to form lyotropic liquid crystal phases in the presence of isotropic host solvents. These effects lead to a wealth of novel applications, many of which will be reviewed in this publication.

New structure induced by elastic anisotropy in cylindrical nematic liquid crystal

2017 ◽  
Vol 13 (2) ◽  
pp. 4705-4717
Author(s):  
Zhang Qian ◽  
Zhou Xuan ◽  
Zhang Zhidong
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Nematic Liquid Crystal ◽  
Elastic Anisotropy ◽  
Nematic Liquid Crystals ◽  
Gennes Theory

Basing on Landau–de Gennes theory, this study investigated the chiral configurations of nematic liquid crystals confined to cylindrical capillaries with homeotropic anchoring on the cylinder walls. When the elastic anisotropy (L2/L1) is large enough, a new structure results from the convergence of two opposite escape directions of the heterochiral twist and escape radial (TER) configurations. The new defect presents when L2/L1≥7 and disappears when L2/L1<7. The new structure possesses a heterochiral hyperbolic defect at the center and two homochiral radial defects on both sides. The two radial defects show different chiralities.

Recent Advances in Application of Azobenzenes Grafted on Mesoporous Silica Nanoparticles in Controlled Drug Delivery Systems Using Light as External Stimulus

2020 ◽  
Vol 20 (11) ◽  
pp. 1001-1016
Author(s):  
Sandra Ramírez-Rave ◽  
María Josefa Bernad-Bernad ◽  
Jesús Gracia-Mora ◽  
Anatoly K. Yatsimirsky
Keyword(s):  
Drug Delivery ◽  
Mesoporous Silica ◽  
Silica Nanoparticles ◽  
Drug Delivery Systems ◽  
Mesoporous Silica Nanoparticles ◽  
High Surface ◽  
Delivery Systems ◽  
Surface Reactivity ◽  
External Stimulus ◽  
Recent Advances

Hybrid materials based on Mesoporous Silica Nanoparticles (MSN) have attracted plentiful attention due to the versatility of their chemistry, and the field of Drug Delivery Systems (DDS) is not an exception. MSN present desirable biocompatibility, high surface area values, and a well-studied surface reactivity for tailoring a vast diversity of chemical moieties. Particularly important for DDS applications is the use of external stimuli for drug release. In this context, light is an exceptional alternative due to its high degree of spatiotemporal precision and non-invasive character, and a large number of promising DDS based on photoswitchable properties of azobenzenes have been recently reported. This review covers the recent advances in design of DDS using light as an external stimulus mostly based on literature published within last years with an emphasis on usually overlooked underlying chemistry, photophysical properties, and supramolecular complexation of azobenzenes.

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