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The introduction of liquid crystals into microcavities has garnered considerable attention for their exceptional tunability and high sensitivity to external perturbation factors within their distinct phase states. Here, a novel light source with both wavelength tunability and an exceptionally narrow linewidth is presented. This innovation is realized by strategically manipulating LC molecules, transitioning them from a well‐aligned state to a disordered state with increasing temperature. The microcavity is tailored to support bound states in the continuum, a cutting‐edge concept in photonic research that allows for light localization with minimal loss. In the pursuit of potential biocompatibility and to reduce cytotoxicity, indium phosphide colloid quantum dots are opted to serve as the emissive carriers within the system. An ultra‐narrow linewidth light emission of 0.039 nm is observed, corresponding to a quality factor reaching 16668, along with a tunable range of 1.21 nm and a temperature sensitivity of 33.52 pm K−1. The invention's compact size and tunable character make it an ideal candidate for a variety of potential applications, such as eco‐friendly sensors with minimal ecological impact, optical modulators with precise control over light, and adaptable photonic devices that can be integrated with a diverse array of materials and configurations. [ABSTRACT FROM AUTHOR]

Underwater organisms exhibit sophisticated propulsion mechanisms, enabling them to navigate fluid environments with exceptional dexterity. Recently, substantial efforts have focused on integrating these movements into soft robots using smart shape‐changing materials, particularly by using light for their propulsion and control. Nonetheless, challenges persist, including slow response times and the need of powerful light beams to actuate the robot. This last can result in unintended sample heating and potentially necessitate tracking specific actuation spots on the swimmer. To tackle these challenges, new azobenzene‐containing photopolymerizable inks are introduced, which can be processed by extrusion printing into liquid crystalline elastomer (LCE) elements of precise shape and morphology. These LCEs exhibit rapid and significant photomechanical response underwater, driven by moderate‐intensity ultraviolet (UV) and green light, being the actuation mechanism predominantly photochemical. Inspired by nature, a biomimetic four‐lapped ephyra‐like LCE swimmer is printed. The periodically illumination of the entire swimmer with moderate‐intensity UV and green light, induces synchronous lappet bending toward the light source and swimmer propulsion away from the light. The platform eliminates the need of localized laser beams and tracking systems to monitor the swimmer's motion through the fluid, making it a versatile tool for creating light‐fueled robotic LCE free‐swimmers. [ABSTRACT FROM AUTHOR]

Optoelectronic and spinoptronic technologies benefit from flexible and tunable coherent light sources combining the best properties of nano- and material-engineering to achieve favorable properties such as chiral lasing and low threshold nonlinearities. In this work we demonstrate an electrically wavelength- and polarization-tunable room temperature polariton laser due to emerging photonic spin–orbit coupling. For this purpose, we design an optical cavity filled with both birefringent nematic liquid crystal and an inorganic perovskite. Our versatile growth method of single CsPbBr3 inorganic perovskite crystals in polymer templates allows us to reach strong light–matter coupling and pump-induced condensation of exciton–polaritons resulting in coherent emission of light. The sensitivity of the liquid crystal to external voltage permits electrical tuning of the condensate energy across 7 nm; its threshold power, allowing us to electrically switch it on and off; and its state of polarization sweeping from linear to locally tilted circularly polarized emission. [ABSTRACT FROM AUTHOR]

Liquid crystal (LC) materials exhibit interesting electro-optic switching and molecular ordering properties. Furthermore, the addition of chemically compatible active emitters such as core-shell quantum dots (QD) in a LC medium allows optical as well as dielectric tuning in an anisotropic, reconfigurable ordered medium. Order in a nematic LC phase is characterized by an orientational order parameter. In this work, we demonstrate the use of patterned substrates to generate arrays of integer topological defects in a nematic LC medium doped with cadmium selenide (core) cadmium sulfide (shell) core–shell QDs. We demonstrate the formation of metastable air-pillar-induced integer topological defects (TDs) in relatively thinner 9 μm LC sandwich cells, and the formation of field-induced TDs in thicker (25 μm) cells. Simultaneously, the self-assembly of core-shell QDs into square arrays on the patterned substrates is discussed, highlighting potential electro-optic device applications. The surfactant hexadecyltrimethylammonium bromide (CTAB) is found to play a significant role in LC TD formation as well as QD spatial organization at the optimized concentration. Self-assembly and ordering of single- and multi-component LCs within structured devices is a highly relevant problem for modern optoelectronic devices. This work opens new possibilities for classical as well as quantum light sources which require spatially ordered optical emitters in a reconfigurable dielectric medium at a micron-scale. [ABSTRACT FROM AUTHOR]

Spatial control over molecular order in polymeric systems will enable advancements in healthcare and photonics, from soft actuators to data storage and encryption. Liquid crystalline (LC) materials are attractive for their intrinsic combination of long‐range anisotropy and fluidity that enables alignment. Photoalignment represents an attractive noncontact ordering mechanism. However, contemporary hurdles preventing widespread implementation of photoalignment include the use of high‐intensity light sources, restrictions to thin films (<1 µm) and specific substrates, multistep LC syntheses, and costly processing. Herein, an interplay between photo‐polymerization and ‐alignment with commercially relevant LCs is reported. Systematic, in situ monitoring of optical anisotropy using a custom microscopy setup provides unique mechanistic insight and facilitates optimization. The optimized process occurs rapidly (<10 min) from an isotropic state with a one‐step exposure to low‐intensity blue linearly polarized light. As a result, substrate‐independent photoalignment of thick (≈6–38 µm), optically transparent LC networks is demonstrated, along with a wide LC‐matrix scope that includes thiol‐containing elastomers. Furthermore, photopatterning provides excellent fidelity (<5 µm) and access to complex images with multiangle optical anisotropy. This user‐friendly process will facilitate production of "smart" (stimuli‐responsive) plastics for improved human health and information security. [ABSTRACT FROM AUTHOR]

In this paper, a new type of full attachment double‐sided liquid crystal display is designed. The liquid crystal screen and optical films are bonded by OCA called full‐ attachment LCD. The double‐sided display mentioned in this paper uses the same light source on both sides, and the light guide plate is made of glass material or nano material. The double‐sided display designed in this paper is ultra‐thin and the border is extremely narrow. It uses a full attachment optical architecture, higher utilization of light sources, and lower power consumption. Because it does not require a double‐sided backplane design, it is lighter. Its performance has been improved, and its cost has been reduced. [ABSTRACT FROM AUTHOR]

The purpose of this study was to maximise circularly polarised luminescence (CPL) utilising chiral templating that manipulates the helical nature of bent-core liquid crystals (BCLC) concentrated with a high quantum-yield luminophore. Using a chiral template and an achiral phosphorescent and liquid crystal emitter that can allow chirality transfer, the resulting complex induces circular polarisation without aggregation-caused quenching events. This enables the integration of our luminophore into a chiral matrix at very high concentrations. Using this new, all-inclusive model in lab, we designed a polarised light source controlled through the helical-type morphology of the template giving access to a highly tunable CPL system with an excellent dissymmetry factor (${g_{lum}}$ g lum ). This system can aid in many optical processes or thermal-rate indicators. [ABSTRACT FROM AUTHOR]

This study presented a new method for surface temperature measurement using thermochromic liquid crystals. In the proposed method, the temperatures over the surface of a sheet of thermochromic liquid crystals were measured using the ratio of the spectral intensities of two specific wavelengths less than 450 nm. The measurable temperature range was broadened by approximately three times that of the conventional methods based on color change. In the experiment, the target object for measuring the surface temperature was a planar copper plate with a sheet of thermochromic liquid crystals on its surface having a color-change range of 10–20 °C; a white light emitting diode was used as the light source. Two monochrome charge-coupled device cameras were used to acquire images of the spectral intensities to eliminate the effect of spatial fluctuations of the light emission on measurement accuracy. The results demonstrated that a measurable temperature range of 21–51 °C with a temperature resolution higher than 0.04 °C was obtained using the ratio of the spectral intensities of two wavelengths, i.e., 442 nm and 436 nm. The uncertainty of the measured temperature was also analyzed. The minimum temperature uncertainty of 0.06 °C was obtained through image processing analysis using a spatial filtering window of size five times five pixels and 500 sequential images for time averaging. [ABSTRACT FROM AUTHOR]

In recent years, photoactive materials have attracted extensive interest in microrobots for their attractive abilities of untethered and tunable control with light. Conventional photo-oscillators based on Azo-containing liquid crystal network require complex surface alignment techniques and light sources with specific wavelengths and polarity, which limits their application in controlled autonomy. Here, we report a facile strategy to create self-oscillating microrobots powered and controlled by a wide spectrum of constant light. The oscillators are composed of a layer of candle soot (CS)-containing liquid crystal elastomer (LCE) attached to a layer of polydimethylsiloxane (PDMS). The strip-shaped oscillators with one end fixed can execute self-sustained oscillation through a self-shadowing mechanism. LCEs with CS as an excellent photo-absorber provides superior photothermal actuation, while PDMS with low viscoelasticity accelerates the actuation-recovery cycle of the oscillator. Our LCE composite photo-oscillators show tunable frequencies and amplitudes by structural and light intensity modulation, showing potential for autonomous soft robotic applications. [ABSTRACT FROM AUTHOR]

Self-oscillation absorbs energy from a steady environment to maintain its own continuous motion, eliminating the need to carry a power supply and controller, which will make the system more lightweight and promising for applications in energy harvesting, soft robotics, and microdevices. In this paper, we present a self-oscillating curling liquid crystal elastomer (LCE) beam-mass system, which is placed on a table and can self-oscillate under steady light. Unlike other self-sustaining systems, the contact surface of the LCE beam with the tabletop exhibits a continuous change in size during self-sustaining curling, resulting in a dynamic boundary problem. Based on the dynamic LCE model, we establish a nonlinear dynamic model of the self-oscillating curling LCE beam considering the dynamic boundary conditions, and numerically calculate its dynamic behavior using the Runge-Kutta method. The existence of two motion patterns in the LCE beam-mass system under steady light are proven by numerical calculation, namely self-curling pattern and stationary pattern. When the energy input to the system exceeds the energy dissipated by air damping, the LCE beam undergoes self-oscillating curling. Furthermore, we investigate the effects of different dimensionless parameters on the critical conditions, the amplitude and the period of the self-curling of LCE beam. Results demonstrate that the light source height, curvature coefficient, light intensity, elastic modulus, damping factor, and gravitational acceleration can modulate the self-curling amplitude and period. The self-curling LCE beam system proposed in this study can be applied to autonomous robots, energy harvesters, and micro-instruments. [ABSTRACT FROM AUTHOR]

Low aperture ratio is a problem in the conventional dual-view integral imaging (DVII) display using a point light source array. A high-aperture-ratio DVII display using a gradient width point light source array is reported in this work. The elemental Images 1 and 2, which are alternatively aligned on a liquid crystal panel, are illuminated by the light rays emitted from an assigned point light source. The optical path is optimized by optimizing the widths of the point light sources. The aperture ratio of the proposed DVII display was demonstrated as 1.88 times the conventional DVII display. Experiments showed that the vertical viewing range is related to the vertical width of the first row point light source, whereas the aperture ratio is related to the vertical widths of all point light sources. By optimizing the widths of the point light sources, the aperture ratio is enhanced without loss of viewing range. [ABSTRACT FROM AUTHOR]

• Anisotropic friction surface is introduced to enable light-fueled self-rotation-eversion in a LCE torus. • A model of a light-fueled self-rotating and self-everting LCE torus is proposed. • The mechanism behind the self-rotation-eversion is elucidated. • The self-rotation and self-eversion angular velocities can be controlled by several parameter. Recent experiments have revealed a new end-to-end ribbon spiral structure capable of demonstrating two interconnected periodic zero-energy-mode self-rotation-eversion in reaction to constant temperature or constant light sources, yet its fabrication is challenging due to its intricate nature. Differently, this paper develops a light-fueled self-rotating and everting liquid crystal elastomer torus on an isotropic frictional plane, by imparting anisotropic frictional properties to the surface of the torus. Based on a mature dynamic liquid crystal elastomer model, we constructed the theoretical model of the torus system. The torus is capable of absorbing the illumination energy to counteract damping dissipation and produce zero-energy-mode self-eversion-rotation. Theoretical findings demonstrate that the angular velocity of self-eversion is influenced by light intensity, light penetration depth, gravitational acceleration and anisotropic friction surface. Moreover, there is a proportional relationship between the self-rotation and self-eversion angular velocities, which is determined by the anisotropic frictional surface. The detailed criterion for the self-rotation direction is also established. Theoretical findings exhibit several similar phenomena to experimental observations. This paper proposes a new simple strategy that utilizes anisotropic friction surface to control self-eversion-rotation, which has guiding significance for the application of soft robots, active devices, and energy harvesters. This study introduces an anisotropic friction surface to facilitate light-driven self-rotation and eversion in a LCE torus, alongside providing criteria for determining the direction of self-rotation. [Display omitted] [ABSTRACT FROM AUTHOR]

VMXm joins the suite of operational macromolecular crystallography beamlines at Diamond Light Source. It has been designed to optimize rotation data collections from protein crystals less than 10 µm and down to below 1 µm in size. The beamline has a fully focused beam of 0.3 × 2.3 µm (vertical × horizontal) with a tuneable energy range (6–28 keV) and high flux (1.6 × 1012 photons s−1 at 12.5 keV). The crystals are housed within a vacuum chamber to minimize background scatter from air. Crystals are plunge‐cooled on cryo‐electron microscopy grids, allowing much of the liquid surrounding the crystals to be removed. These factors improve the signal‐to‐noise during data collection and the lifetime of the microcrystals can be prolonged by exploiting photoelectron escape. A novel in vacuo sample environment has been designed which also houses a scanning electron microscope to aid with sample visualization. This combination of features at VMXm allows measurements at the physical limits of X‐ray crystallography on biomacromolecules to be explored and exploited. [ABSTRACT FROM AUTHOR]

"How would you build a robot, the size of a bacteria, powered by light, that would swim towards the light source, escape from it, or could be controlled by means of different light colors, intensities or polarizations?" This was the question that Professor Diederik Wiersma asked PW on a sunny spring day in 2012, when they first met at LENS—the European Laboratory of Nonlinear Spectroscopy—in Sesto Fiorentino, just outside Florence in northern Italy. It was not just a vague question, as Prof. Wiersma, then the LENS director and leader of one of its research groups, already had an idea (and an ERC grant) about how to actually make such micro-robots, using a class of light-responsive oriented polymers, liquid crystal elastomers (LCEs), combined with the most advanced fabrication technique—two-photon 3D laser photolithography. Indeed, over the next few years, the LCE technology, successfully married with the so-called direct laser writing at LENS, resulted in a 60 micrometer long walker developed in Prof. Wiersma's group (as, surprisingly, walking at that stage proved to be easier than swimming). After completing his post-doc at LENS, PW returned to his home Faculty of Physics at the University of Warsaw, and started experimenting with LCE, both in micrometer and millimeter scales, in his newly established Photonic Nanostructure Facility. This paper is a review of how the ideas of using light-powered soft actuators in micromechanics and micro-robotics have been evolving in Warsaw over the last decade and what the outcomes have been so far. [ABSTRACT FROM AUTHOR]

Microlasers integrated with biological systems have received tremendous attention for their intense light intensity and narrow linewidth recently, serving as a powerful tool for studying complex dynamics and interactions in scattered biological micro-environments. However, manipulation of microlasers with controllable motions and versatile functions remains elusive. Herein, we introduce the concept of motor-like microlasers formed by magnetic-doped liquid crystal droplets, in which the direction and velocity could be controlled by altering internal magnetic nanoparticles or external magnetic fields. Both translational and rotatory motions of the lasing resonator could be continually changed in real-time. Lasing-encoded motors carrying different functions and lasing wavelengths were also achieved. Finally, we demonstrate the potential of motor-like microlasers by functioning as a localized stimulation emission light source to stimulate or illuminate living cells, providing a novel approach for switching on/off light emissions and subcellular imaging. Laser emitting micromotors offer a facile system for precise manipulation of microlasers in biological fluids, providing new insight into the development of programmable on-chip laser devices and laser-emitting intelligent systems. [ABSTRACT FROM AUTHOR]

In response to the problems of the existing partition toning technology based on liquid crystal backlight needs to add metal physical grilles with high alignment accuracy to prevent the crosstalk of different colors and brightnesses of light between the partitions, this paper proposes a structural design of the optical cavity without grille and its key parameter value intervals, and puts forward a low‐color crosstalk evaluation method. Based on this method, the light output effect of the diffuser is evaluated, and the distance between the diffuser and the RGB mini‐LED light source as well as the structural parameters of the light‐guiding cavity between them are reasonably adjusted. The grilleless optical cavity structure studied in this paper has the advantages of simple structure, low cost and easy implementation, ensuring regional dimming and regional color mixing while further improving the color crosstalk phenomenon between the backlight partitions. [ABSTRACT FROM AUTHOR]

Crosslinked liquid crystal polymers (CLCPs) have recently attracted much attention because they exhibit unique properties in stimuli responsiveness. We have recently focused on the photoinduced deformation behavior of CLCP containing N-benzylideneaniline (NBA) as a photoresponsive moiety. We prepared two types uniaxially aligned NBA-containing crosslinked liquid crystalline polymer film, homogeneous and homeotropic, and evaluated its photomechanical properties. The initial alignment of photoactive mesogens significantly affects the bending behavior of the CLCP films: the homogeneous films bent toward the irradiation direction of the actinic UV light, while the homeotropic films bent away from the light source. [ABSTRACT FROM AUTHOR]

Soft actuators controlled by untethered methods have aroused growing attention on account of their flexibility and controllability. Soft actuators shaped in a one-dimensional structure are highly desired in diverse practical applications. In this paper, we fabricate a new core-shell CNTs@LCE fiber soft actuator made of a liquid crystal elastomer (LCE) fiber coating with carbon nanotubes (CNTs) shell. Thanks to the outstanding photothermal conversion capacity of CNTs and remarkable thermal-contraction characteristic of LCE, the obtained core-shell CNTs@LCE fiber actuator can be controlled by near-infrared light with excellent phototropic bending to arbitrary directions, lifting loads more than 4600 times of its own weight and acting as artificial muscle to control the feature of biomimetic elbow and gripper with loads. More intriguingly, the core-shell CNTs@LCE fiber can fulfill unprecedented photo-driven phototropic locomotion including tracking the moving light source, climbing a slanted surface, and optically steering as well. The involved unique photo-driven phototropic movement mechanism has been revealed experimentally and theoretically, which is highly expected to guide the fabrication of other soft smart fiber actuators for advanced applications. [Display omitted] • New robust core-shell fiber soft actuators with excellent photo-powered actuation behaviors. • Photo-fueled high-strength artificial muscle. • Unprecedented photo-driven phototropic locomotion of 1D-shaped soft actuators with high controllability and adaptability. [ABSTRACT FROM AUTHOR]

Through filling the liquid crystal into the air holes of a dual-core holey fiber with a simple structure, the transmission mechanism of the fiber is changed from total internal reflection to photonic bandgap (PBG), and a polarization splitter based on the liquid crystal-filled dual-core PBG holey fiber is investigated. The results demonstrate that, by setting appropriate geometrical parameters, the polarization splitter possesses a short length of 890.5 μm, and its wide bandwidth of ~150 nm almost covers all the S, C, and L communication bands. Besides, it has an excellent electro-interference- resistance property and certain sensitivity to temperature. [ABSTRACT FROM AUTHOR]

The high-efficient development, storage and transportation of waxy crude oil has a significant meaning for stable supply of petroleum energy. The variety of complex morphology and microstructure of wax crystals promote complicated physical properties of waxy crude oil, which increases the difficulty of high-efficient use. At present, most of the existing research focuses on the quiescent structure and morphology of wax crystals. In this work, a new in situ microscopic observation system is introduced, together with the self-created multi-angle composite light source. The microscopic motions and structure dynamic transformation of wax crystals in the waxy crude oil subjected to shear has been first achieved. The new insights will enhance the understanding of the behavior of wax crystals in response to shear, revealing the gelation mechanism and helping the development of a high-efficient pour point depressant. Our outcomes reveal that the aggregation between wax crystals plays an important role throughout the entire microstructure evolution. Two motion modes of wax crystals are observed, including the synchronous motion that follows liquid hydrocarbons, and individual motions of rotation, torsion and stretch in 3-D. Three critical moments related to the microstructure evolution are first found, (I) the increasing individual aggregates instead of the free wax crystals. Correspondingly, two motion modes both exist with high activity. (II) The accomplishment of interconnection between aggregates in the 2-D plane implying the formation of the 2-D network structure. Correspondingly, the individual motions vanish and the synchronous motion begins to decrease. (III) The interlocking between wax crystals in different liquid layers increases to surpass the shear stress, implying the formation of the 3-D network structure. Correspondingly, all forms of motion cease. When the shear rate is low, it can promote aggregation. As it increases, the impact is different and depends on the inherent structure of crude oil. Two opposite effects may exist simultaneously. [ABSTRACT FROM AUTHOR]

Serial data collection has emerged as a major tool for data collection at state‐of‐the‐art light sources, such as microfocus beamlines at synchrotrons and X‐ray free‐electron lasers. Challenging targets, characterized by small crystal sizes, weak diffraction and stringent dose limits, benefit most from these methods. Here, the use of a thin support made of a polymer‐based membrane for performing serial data collection or screening experiments is demonstrated. It is shown that these supports are suitable for a wide range of protein crystals suspended in liquids. The supports have also proved to be applicable to challenging cases such as membrane proteins growing in the sponge phase. The sample‐deposition method is simple and robust, as well as flexible and adaptable to a variety of cases. It results in an optimally thin specimen providing low background while maintaining minute amounts of mother liquor around the crystals. The 2 × 2 mm area enables the deposition of up to several microlitres of liquid. Imaging and visualization of the crystals are straightforward on the highly transparent membrane. Thanks to their affordable fabrication, these supports have the potential to become an attractive option for serial experiments at synchrotrons and free‐electron lasers. [ABSTRACT FROM AUTHOR]

A polarization‐independent refractive index (RI) sensor with a sensitivity of 50 nm/RIU is demonstrated. The proposed RI sensor simply consists of a liquid crystal (LC) polymeric polarization grating film and one glass substrate. The wavelength shift over the RI of the surrounding medium is investigated through anisotropic rigorous coupled‐wave analysis. Such an LC‐based polarization‐independent RI sensor not only enables the usage of an unpolarized light source but also manifests a high sensitivity, offering great potential for the integration with display systems. [ABSTRACT FROM AUTHOR]

A polarization independent refractive index (RI) sensor with a RI sensitivity of 50 nm/RIU is demonstrated. The proposed RI sensor simply consists of a liquid crystal (LC) polymeric polarization grating film and one glass substrate. The wavelength shift over the refractive index of surrounding medium is investigated through anisotropic rigorous coupled‐wave analysis. Such a LC‐based polarization independent RI sensor not only enables the usage of an unpolarized light source but also manifests a high sensitivity, offering great potential for the integration with display systems. [ABSTRACT FROM AUTHOR]

We report the results of measurements of the threshold of Freedericksz transition in a nematic liquid crystal doped by Methyl-red. We show that in case of dc field the threshold voltage can decrease or increase depending on the light dose, due to the light-induced desorption and adsorption of charge complexes from and on the irradiated surface, that has been recently demonstrated. This effect has the potential to be exploited in optical devices such as liquid crystal microlenses and spatial light modulators. [ABSTRACT FROM AUTHOR]

We perform molecular dynamics simulations of a nematic liquid crystal flowing around a colloidal particle. We study the flow-induced modifications of the topological defects in the liquid crystal due to the presence of the colloid. We show that flow distorts Boojum defects into an asymmetrically larger downstream lobe, and that Saturn ring defects are convected downstream along the flow direction, which is in agreement with experimental observations. Additionally, for a Janus colloid with both parallel and perpendicular patches, exhibiting a Boojum defect and a Saturn ring defect, we find that the Boojum defect facing the upstream direction is destroyed and the Saturn ring is convected downstream. [ABSTRACT FROM AUTHOR]

The peculiarities in the dynamics of the director reorientation in confined nematic liquid crystals (LCs) under the influence of a strong electric field E have been investigated theoretically based on the hydrodynamic theory including the director motion with appropriate boundary and initial conditions. Analysis of the numerical results for the turn-on process provides an evidence for the appearance of the spatially periodic patterns in confined LC film, only in response to the suddenly applied strong E. It has been shown that there is a threshold value of the amplitude of the thermal fluctuations of the director over the LC sample which provides the nonuniform rotation mode rather than the uniform one, whereas the lower values of the amplitude dominate the uniform mode. During the turn-off process, the reorientation of the director to the direction preferred by the surfaces is characterized by the complex destruction of the initially periodic structure to a monodomain state. [ABSTRACT FROM AUTHOR]

We propose a dual‐view integral imaging display based on point light sources. The proposed dual‐view integral imaging display is composed of an organic light‐emitting diode and a liquid crystal panel. The point light sources are displayed on the organic light‐emitting diode. The elemental images 1 and 2, which are captured from three‐dimensional scenes 1 and 2, are alternatively aligned on the liquid crystal panel in the horizontal direction. Two adjacent elemental images 1 and 2 are coupled and corresponded to one point light source. The coupled elemental images 1 and 2 are illuminated by the corresponding point light source. It satisfies the practical applications that the viewing zones are respectively located at the left and right of the proposed dual‐view integral imaging display. A prototype of the proposed dual‐view integral imaging display is developed, and good verifying results are obtained. [ABSTRACT FROM AUTHOR]

We have investigated the fundamental operation characteristics of light-emitting liquid crystals with an emissive layer of fluorescent dye-doped nematic liquid crystal under the condition of applied AC voltage. The electric field dependent current and luminance properties for different frequencies are satisfactorily explained by an equivalent circuit analysis. We confirm that the luminance steeply plunges as the frequency increases. Such a great suppression is explained by accounting for the cut-off properties of the equivalent circuit and for the effect of ions drift mobility. [ABSTRACT FROM AUTHOR]

Introduction: Three original cosmetic formulations containing retinol as an active component with liquid crystal, lamellar, and lipid bases were prepared. The formulas contain different concentrations of retinol, that is, 0.5%, 0.3%, and 0.15%. Objectives: The aim of the study was to evaluate a spectrophotometric method for assessing the quantity of retinol in the nine cosmetic products and to determine the viscosity of each formula. Materials and Methods: The formulations were tested for stability; final product testing was preceded by sample weighing and pH measurement as well as exposure to the light source from xenon lamp that maps solar radiation in the range of 310‐800 nm. Microbiological purity test was performed according to the PN‐EN ISO 29621:2011 method and viscosity carried out using a cone‐plate digital rheometer (DV‐III Brookfield, version 3.0) on 0.5 cm3 emulsion samples at 32°C. The retinol content in preparations was assayed by UV spectrophotometry. Results: Each of prepared cosmetic products with retinol storing in a room temperature occurred to be stable. The liquid crystal emulsion has the higher viscosity than lamellar and lipid emulsions. Although the retinol concentration in lipid serum was determined with high accuracy, the method has some limitations associated with differences between the lipid cosmetic base and the lamellar and liquid crystal sera. Nevertheless, the UV spectrophotometric method described herein is a simple and highly accurate approach for determining the retinol content in lipid cosmetics: Its coefficient of correlation was R2 = 0.9982 with a relative standard deviation (n = 3) in the range of 0.5%‐1.5%. Conclusion: The presented UV spectrophotometric method represents an effective tool for fast and accurate determination of retinol content in lipid formulations. Probably, the method could be used in studies of other retinol‐based preparations, for example, medications, and for determining the effective life of retinol‐containing products in storage. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate a non-interferometric phase imaging technique based on modified transport of intensity equation (TIE) through a liquid crystal variable retarder (LCVR) and partial coherent illumination. The LCVR has been used in pure phase shifter configuration for creating refractive index variation. The modified TIE eliminates the need of mechanical displacement of camera or object, since it needs recording of only two intensity images with different refractive indices. A light-emitting diode (LED) has been used as a light source to avoid the usual speckle problems in coherent imaging. Although LCVR is a versatile device, its application towards phase recovery is less studied. The applicability of the method has been demonstrated through imaging a USAF resolution chart, ultra-violet glue drop, micro-lens, and onion's peel. The result of onion's peel has also been compared with a commercial bright-field microscope. [ABSTRACT FROM AUTHOR]

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Optical properties of homeotropically aligned flexoelectric nematic layers deformed by dc electric fields were analyzed by calculating the phase difference Δ[uppercase_phi_synonym] between ordinary and extraordinary light rays passing through a layer placed between crossed polarizers. A phase difference arises when the bias voltage U exceeds the threshold value UT. Close to the threshold, Δ[uppercase_phi_synonym] increases linearly with U. The possibility of using this effect to detect the flexoelectric properties of the nematic was explored by simulated experiments. The method considered in this paper is based on measurement of the slope of the linear section of the voltage dependence of Δ[uppercase_phi_synonym], which depends on the sum of the flexoelectric coefficients and which differs from a well-known theoretical slope that ignores flexoelectric properties. The difference between the slopes reveals the flexoelectric properties of the nematic. The effectiveness of the proposed method is discussed. [ABSTRACT FROM AUTHOR]

The reflection notch bandwidth of a cholesteric liquid crystal (CLC), equal to the product of the liquid crystal (LC) birefringence (Δn), and the pitch length (po), is typically on the order of 50-100 nm in the visible portion of the electromagnetic spectrum. Static bandwidths greater than 100 nm can be observed in CLCs that possess a pitch gradient throughout the thickness of the cell. In this work, we report on polymer stabilized CLC (PSCLC) systems that exhibit electrically controllable, dynamic bandwidths governed by the strength of a direct current (DC) electric field applied across the sample. Symmetric notch broadening which increases linearly with field and reaches a maximum value at 4 V/μm is observed. Removal of the field returns the PSCLC cell to its original optical properties. A seven fold increase in bandwidth was observed for 22 μm thick cells which contained LCs with a small birefringence (∼0.04). A variety of CLC mixtures with small positive or negative dielectric anisotropies are shown to exhibit this reversible dynamic bandwidth broadening. The magnitude of the effect was dependent on the amount of polymer stabilization controlled by initial monomer content. The underlying mechanism is partially elucidated by examining cells simultaneously in transmission and reflection and observing differences when modulating the DC polarity across the cell. Different mechanisms for the observed effects are discussed in terms of consistency with our experimental results. [ABSTRACT FROM AUTHOR]

In this work, we study Si-based three-dimensional photonic crystals infiltrated with liquid crystal (LC), within a one-dimensional effective medium model. Two specific systems of diamond crystal structure compatible with the mature Si technology are considered, namely, (i) diamond-1 which is composed of LC spheres embedded in the Si background, and (ii) diamond-2 which is the inverse of the foregoing structure, with Si spheres immersed in the LC background. For each system, the study is carried out with the LC being in the isotropic/nematic phase. The one-dimensional effective medium model employed in the study is an improved version of the conventional mean field theory (MFT). While retaining partially the typical advantage of MFT, e.g., physical transparency, analytical capability, and computational efficiency, it goes beyond the conventional MFT by taking into account the modulation of dielectric constant in the direction of wave propagation. As such, it improves greatly the poor numerical accuracy inherent in the MFT. We find a partial gap between the 2nd and 3rd bands, with the gap-to-midgap ratio being a few percents. Moreover, the edge of partial gap may be shifted by about 1% (in relative unit) when optical, thermal, or electrical means are applied to alter the phase of LC or rotate the axis of nematic molecules. [ABSTRACT FROM AUTHOR]

Liquid crystal alignment on polymer line gratings fabricated by a soft lithography embossing process derived from PRINTTM (Pattern Replication In Nonwetting Template) is influenced by mold removal (peel-off direction). This indicates the existence of two competing alignment mechanisms: (1) topography (i.e., the Beremann mechanism) and (2) surface modification during peel-off. The degree to which mold removal influenced liquid crystal alignment was found to be dependent on the primary structures of the embossed polymer, and the chemical composition of the mold. These findings suggest alternate ways to affect liquid crystal alignment in roll-to-roll manufacturing. [ABSTRACT FROM AUTHOR]

We describe an experimental procedure for accurate measurement of anchoring energy strength of liquid crystal cells. This technique is based on the possibility of gathering a large amount of very precise data about the linear optical response of the cell in different experimental conditions, using spectroscopic ellipsometry. Then, a careful data analysis exploiting data inversion method, supplemented by simulations from the elastic theory, is able to provide the searched information. The technique has been applied to vertical aligned nematic cells, chosen for its widespread use in the present display market. The results obtained in this particular case together with a thorough comparison with existing alternative techniques, suggest that our technique can be an optimum candidate for the industrial implementation of such measurement. A particular example is fully worked out, giving a result with a precision of 1.5% and an accuracy of 10%. [ABSTRACT FROM AUTHOR]

We have considered a homogeneously aligned liquid crystal (HALC) microvolume, confined between two infinitely long horizontal coaxial cylinders subjected to both a temperature gradient ∇T and radially applied electric field E. We have investigated dynamic field pumping, i.e., studied the interaction between director, velocity, electric fields, as well as, a radially applied temperature gradient, where the inner cylinder is kept at a lower temperature than the outer one. Flexoelectric polarization P has been taken into account as well, and modeled via the classical Meyer treatment. In order to elucidate the role of ∇T, E, and P in producing hydrodynamic flow, we have carried out a numerical study of a system of hydrodynamic equations including director reorientation, fluid flow, and temperature redistribution across the HALC cavity. Calculations show that there exists a range of parameter values (voltage and curvature of the inner cylinder) producing a kinklike orientation process in the system, as well as a nonstandard pumping regime with maximum flow near the hot cylinder. [ABSTRACT FROM AUTHOR]

We present a mean field theory to describe phase separations in mixtures of a liquid crystal and a nanocolloidal particle. By taking into account a nematic, a smectic A ordering of the liquid crystal, and a crystalline ordering of the nanoparticle, we calculate the phase diagrams on the temperature-concentration plane. We predict various phase separations, such as a smectic A-crystal phase separation and a smectic A-isotropic-crystal triple point, etc., depending on the interactions between the liquid crystal and the colloidal surface. Inside binodal curves, we find new unstable and metastable regions, which are important in the phase ordering dynamics. We also find a crystalline ordering of the nanoparticles dispersed in a smectic A phase and a nematic phase. The cooperative phenomena between liquid-crystalline ordering and crystalline ordering induce a variety of phase diagrams. [ABSTRACT FROM AUTHOR]

We investigate when it is possible to introduce surface physical parameters characterizing the nematic/substrate interface. The analysis is performed by solving the problem assuming that the presence of the surface introduces a spatial variation, mainly localized close to the limiting surfaces, of the bulk properties of the nematic (delocalized model). The results of the calculation are compared to the prediction of a model in which the presence of the surface is taken into account by means of new physical parameters, localized to the surface (localized model). We show that if the viscous dissipative effects or the surface alignment effects are considered, the two models predict the same relaxation times and the same threshold for the Freedericksz transition is obtained. From these results we deduce that the localized models are equivalent to the delocalized ones. A continuum description of the interfacial layer of nematic liquid crystals in contact with solid surface in terms of surface properties is then correct, which makes the solution of this kind of problems simpler. Also a softening of the elastic constants near the surfaces can be represented by a localized surface energy term. [ABSTRACT FROM AUTHOR]

We propose a method to confirm the biaxial phase in thermotropic nematic liquid crystals from measurement of the electro-optic characteristics. The electro-optic transmittance curve shows monotonic decrease to zero in the uniaxial phase but the curve shows a U-shaped behavior (or a monotonic decrease to nonzero transmittance) in the biaxial phase. In a bent-core mesogen 4,4′(1,3,4oxadiazole2,5diyl)dipheptylbenzoate (ODBP-Ph-C7), known to be in the nematic phase at temperatures between 173 and 222 °C, it has been found that its electro-optic curve at 190 °C shows a U-shaped behavior, while the curve at 210 °C shows a monotonic decrease to zero transmittance. We believe that these experimental results confirm the biaxial nature of ODBP-Ph-C7. [ABSTRACT FROM AUTHOR]

Two substrates were coated with a mixture containing two polyamic acids. One of the polyamic acids has an alkyl side chain and ordinarily is used for vertical liquid crystal alignment. The other polyamic acid does not have a side chain and ordinarily is used for planar liquid crystal alignment. The substrates were baked in order to promote imidization. It was observed that over a wide concentration range of mixtures the two polymer species comprising the alignment layer do not phase separate. A cell then was constructed and filled with the liquid crystal pentylcyanobiphenyl. It was found that the nematic pretilt angle θ0 is a function of the relative polymer concentration and can be controlled over the range from near 0° to ∼70° with respect to the vertical orientation. A model is proposed in which quartic terms in the surface energy are responsible for the variation of θ0 with concentration. [ABSTRACT FROM AUTHOR]

In liquid crystals, while the second and fourth rank orientational order parameters characterizing a nematic phase can be experimentally determined via several techniques, there is no straightforward experiment rendering the positional order parameters characterizing a smectic A phase. This work illustrates a novel method to estimate the positional order parameters of a smectogenic liquid crystal solvent from knowledge of the orientational order parameters of a number of solutes dissolved therein. The latter order parameters can be experimentally determined via liquid crystal NMR spectroscopy. These data can be then analyzed with a statistical-thermodynamic density functional theory, whose basic ingredient is a model for solute-solvent intermolecular interactions. Its parametrization and the subsequent fitting procedure eventually permit one to obtain the positional order parameters of the solvent besides the positional-orientational distribution function of the solutes. The method is applied to the smectogen 4,4′-di-n-heptyl-azoxybenzene, in which the solutes 1,4-dichlorobenzene and naphthalene have been dissolved. With the help of this exploratory practical example, pros and cons of the method are pointed out and further developments prospected. [ABSTRACT FROM AUTHOR]

We have measured the frequency dependence and temperature dependence of the optical constants of a liquid crystal 4′-n-pentyl-4-cyanobiphenyl (5CB) in both nematic and isotropic phases by using terahertz time-domain spectroscopy. The extinction coefficient of 5CB is less than 0.02 and without sharp absorption features in the frequency range of 0.2–1.0 THz. The extraordinary and ordinary indices of refraction at 25 °C are around 1.77 and 1.58, respectively, giving rise to a birefringence of 0.20±0.02 in this frequency range. The temperature-dependent order parameter extracted from birefringence agrees with the results from the visible region quite well. [ABSTRACT FROM AUTHOR]

The order parameters of a number of different solutes dissolved in a number of different nematic liquid-crystal solvents are measured and compared. It is shown that the order parameters can all be rationalized with the ansatz that there exist two independent ordering mechanisms operating in the liquid crystals employed. With this ansatz it is possible to fit the experimental order parameters to better than 5%. This opens the possibility of the accurate prediction of order parameters in ordered liquids. [ABSTRACT FROM AUTHOR]

Refractive index gradient formation in liquid crystal cells during the application of an electric field across patterned electrodes was studied. The cells were characterized by measuring the intensity profile of a parallel beam of light passing through the cells. Most of the measurements were performed using transparent electrodes comprising periodic straight-line patterns with a conducting linewidth of 4 μm and various pitches in the range of 34–54 μm. The intensity profiles through such cells were studied and it was observed that the intensity showed oscillations as a function of angle. Director profiles were calculated in order to estimate the effective refractive index distribution within the cells. Using this input in theoretical models based on wave theory as well as geometrical optics, intensity profiles could be estimated. The limits of each theory were illustrated and it was shown that the oscillations in the intensity profile could be explained by the wave theory. The effects of the orientation of the molecules with respect to the electrode lines and cell surfaces and its influence on twist of the molecules leading to depolarization of light were investigated. Various other parameters such as the pitch and the cell thickness on the refractive index gradient formation and the resulting light distribution through the cells were also studied. [ABSTRACT FROM AUTHOR]

The influence of controlled-pore glass (CPG) confinement on the phase behavior of octylcyanobiphenyl liquid crystal (LC) is studied by means of x-ray scattering and high precision calorimetry. For CPG samples with pore diameter 2R>24 nm, the smectic order parameter temperature dependence η(T) reveals apparent presmectic ordering far above the bulk smectic A–nematic (SmA-N) phase transition for both nontreated and silane-treated CPG matrices. The behavior of η(T) is qualitatively similar in all samples, well obeying the mean field approach (MFA) in which the surface wetting tendency plays the dominant role. In contrast, the critical fluctuations remain important in the specific heat data, which cannot be described within the MFA. We show experimentally that randomness and surface wetting become dominant over finite-size effects for 2R≤=10 nm, in agreement with theoretical analysis. In nontreated samples, the noncritical character of the static disorder and the interfacial LC-CPG coupling almost completely suppress the quasi-SmA-N and nematic-isotropic phase transitions at 2R∼15.1 and ∼7.5 nm, respectively. [ABSTRACT FROM AUTHOR]