Electrically tunable gradient-index lenses via liquid crystals: beyond the power law.

In this study we present an investigation of electrically tunable progressive lenses utilizing liquid crystals (LC). We introduce a polarized progressive LC lens capable of dynamically adjusting its focal length, functioning as either a positive or negative lens. Our findings reveal that the spatial distribution of lens power within the progressive LC lens, ranging from +4D to -3D, far surpassing the range of -0.87D to +0.87D which one may expect within the parabolic wavefront approximation. For a lens with a 30 mm aperture a total tunable range is 7.6 D (from +5.6D to -2D) which is 4.75 times larger than the traditional parabolic prediction∼1.6D (from +0.8D to -0.8D). This study not only challenges conventional limitations set by optical phase differences in gradient-index LC lenses (the power law) but also ushers in a new possibility for ophthalmic applications. The profound insights and outcomes presented in this paper redefine the landscape of LC lenses, paving the way for transformative advancements in optics and beyond.

Liquid crystal lens set in augmented reality systems and virtual reality systems for rapidly varifocal images and vision correction: erratum.

We have an addendum for our previous paper [Opt. Express30, 22768 (2022)10.1364/OE.461378] cite previous prior works from the N. A. Riza lab that earlier reported a high speed lens based on digital polarization switching in cascade with birefringent fixed and tunable optical beamforming elements and its application for volumetric displays.

Liquid crystal lens set in augmented reality systems and virtual reality systems for rapidly varifocal images and vision correction.

The major challenges of augmented reality (AR) systems and virtual reality (VR) systems are varifocal images for vergence-accommodation conflict (VAC) and vision corrections. In this paper, we design a liquid crystal (LC) lens set consisting of three LC lenses for varifocal images and vision corrections in AR and VR. Four operating modes of such a LC lens set present three electrically tunable lens powers: 0, -0.79 diopters, -2 diopters, and -3.06 diopters by means of manipulation of polarization of incident light using electrically tunable half-wave-plates. The response time is fast(< 50 ms). We also demonstrate AR and VR systems by adopting the LC lens set to exhibit functions of varifocal images and vision corrections which enable to solve VAC as well as vision problem in AR and VR.

Image-based polarization detection and material recognition.

We demonstrate a single-shot and image-based polarization detection system for material recognition. The Stokes parameters are measured under a single-shot measurement using 4 electrically tunable liquid crystal wave plates, 4 polarizers, and 4 camera modules. The optical principle is introduced and the experiments are performed. We also use a metallic plate and a glass substrate to demonstrate the material recognition. The impact of this study is to provide a practical way in image-based polarization detection in Advanced Driver Assistance Systems for material recognition which could help in driving safety.

Study on the performance of high-voltage deep ultraviolet light-emitting diodes.

This study fabricated high-voltage, low-current DUV-LEDs by connecting two devices. Due to better current spreading and the enhanced reflective mirror effect, high-voltage devices present a higher dynamic resistance, emission output power, wall-plug efficiency, external quantum efficiency, and view angle than single traditional devices. The study found that when the injection current was 320 mA, the maximum output power was exhibited at 47.1 mW in the HV sample. The maximum WPE and EQE of high-voltage DUV-LEDs were 2.46% and 5.48%, respectively. Noteworthily, the redshift wavelength shifted from 287.5 to 280.5 nm, less than the traditional device-from 278 to 282 nm. Further, due to the uniform emission patterns in high-voltage devices, the view angle presents 130 degrees at 100 mA input current. In this study, the high-voltage device showed more excellent properties than the traditional device. In particular, it presented a high potential application in high-voltage circuits, which can remove transformers to eliminate extra power consumption.

Generation of vector vortex beams by axially symmetric sheared polymer network liquid crystals.

Liquid crystals have been widely used in optoelectronic devices because of their fast response and excellent electro-optic properties. Featuring a unique ability to manipulate light, they are also proposed as a good candidate in topological photonics for further applications. In this study, an axially symmetric sheared polymer network liquid crystal (ASPNLC) is fabricated to demonstrate vector vortex beams. Linearly and circularly polarized light is used to illuminate the sample, and the output vector vortex beams generated from the ASPNLC indicate that the polarization states of the output beams are dependent on the polarization of the incident light. The measured phenomena are modeled on the bases of phase retardation and Jones calculus to eventually calculate the polarization-resolved intensity profiles accordingly. Hence, our experimental study provides a holistic understanding of the method for generating vector vortex beams by an ASPNLC, which is expected to enhance the knowledge of optical mechanisms for liquid crystal applications.

Intraoperative OK-432 pleurodesis for preventing recurrence of primary spontaneous pneumothorax in children and adolescents: a single-center experience.

BACKGROUND: Primary spontaneous pneumothorax (PSP) commonly occurs in lean, tall, male children and adolescents. To reduce recurrence rates of PSP, chemical pleurodesis could be helpful for patients undergoing video-assisted thoracoscopic surgery (VATS) wedge bullectomy. The efficacy and safety of intraoperative OK-432 (Picibanil) pleurodesis on preventing the recurrence of PSP in pediatric patients remain unclear. METHODS: It is a retrospective observational study in a single center, between 2014 and 2020, enrolled 48 (8 females) pediatric PSP patients with persistent air leakage at the mean age of 16.3 ± 1.1 years to receive VATS wedge bullectomy and pleural abrasion. Twenty patients received additional intraoperative OK-432 pleurodesis. The clinical characteristics of patients, surgical outcomes, and recurrence rates were analyzed. RESULTS: The OK-432 group had longer operation time (118.6 ± 35.6 vs. 96.5 ± 23.3 min; p < 0.05) and higher proportion of postoperative fever (75.0% vs. 28.5%; p = 0.015) than the standard group. No serious adverse events were noted and other surgical outcomes in the two groups were comparable. After a mean follow-up period of 18.1 ± 19.1 months, the OK-432 group had a lower recurrence rate compared with the standard group (5% vs. 28.6%; p < 0.05, odds ratio 0.13, 95% confidence interval: 0.01-1.15), but it had no significant difference in statistics on the Kaplan-Meier curves (log-rank p = 0.105). CONCLUSION: It was the first study that focused on the addition of intraoperative OK-432 pleurodesis for PSP with persistent air leakage in children and adolescents receiving VATS. It demonstrated the efficacy with a low recurrence rate and short-term safety as a single-center experience. LEVEL OF EVIDENCE: Retrospective review, therapeutic study, Level III.

Neuroendocrine Carcinoma of the Endometrium with Ectopic Secretion of Parathyroid Hormone Presenting as Hypercalcemia- Related Posterior Reversible Encephalopathy syndrome: A Case Report.

PURPOSE: Posterior reversible encephalopathy syndrome (PRES) displayed various acute neurological symptoms. PRES is a rare presentation of hypercalcemia. Here we present a case with ectopic secretion of parathyroid hormone from neuroendocrine carcinoma of the endometrium presenting as hypercalcemia-related PRES. CASE REPORT: A 67-year-old woman presented with acute generalized tonic-clonic seizure followed by post-ictal confusion and neuropsychiatric behaviors. The diagnosis is PRES. Investigations showed uterine cervical region with multiple liver metastasis complicated with hypercalcemia, elevated intact parathyroid hormone. Further pathology concluded as a poorly differentiated adenocarcinoma of the endometrium with neuroendocrine differentiation and immunoreactive for PTH. The patient's neurologic manifestations had resolved. Serum free calcium level and intact-PTH had declined after first course of definitive chemoradiation. CONCLUSION: Immunostaining of the tumor tissue can be used to estimate the ectopic PTH production within the tumor cells. Early detection and appropriate clinical treatment hold the potential to improve the prognosis of refractory hypercalcemia and hypercalcemia related PRES. Keyword: Posterior reversible encephalopathy syndrome; hypercalcemia; intact-parathyroid hormone; parathyroid hormone-related peptide; neuroendocrine carcinoma of endometrium.

Electrically tunable polarization independent liquid crystal lenses based on orthogonally anisotropic orientations on adjacent micro-domains.

Polarization dependency is an intrinsic property of liquid crystals (LC) devices but major problem is optical efficiency. We demonstrated a polarization independent liquid crystal phase modulation based on the orthogonal nematic LC (OLC) mode wherein the optics axes of nematic liquid crystal molecules are set orthogonally to adjacent sub-domains for the first time. Such an OLC mode includes sub-domain with anisotropic orientations but collectively presents a capability of a polarizer-free optical phase modulation. An OLC mode cell provides a tunable optical phase of ∼3.35π radians for unpolarized light and different linearly polarized light. Among the polarizer-free LC mode, the proposed OLC mode is single-layered with large tunable optical phase. We also demonstrated a polarizer-free LC micro-lens. We expect this novel LC mode provide alternatives technology roadmap for upcoming optical applications, such as electrically tunable ophthalmic lenses and optical systems for augmented reality.

Optical measurement in a curved optical medium with optical birefringence and anisotropic absorption.

The planar optical mediums with properties of either birefringence (i.e., waveplates) or anisotropic absorption (i.e., polarizers) are well studied. However, how a beam propagates in a birefringent curved medium with anisotropic absorption, especially for curved-sheet polarizers, still needs to be investigated. In this paper, we study optical wave propagation through a curved-birefringent medium with anisotropic absorption. We built an optical model based on the Mueller matrix to predict the spatial distributions in light intensity and polarization when light propagates in a curved-birefringent medium with anisotropic absorption. To demonstrate how to use the optical model, the experiments based on ellipsometry are also performed. The impact of this study is to analyze the light propagation in birefringent-curved medium with anisotropic absorption, which could affect the performance of curved liquid crystal devices with curved polarizers, such as curved liquid crystal displays (LCDs), flexible LCDs, and flexible LC lenses.

STIM1 Controls the Focal Adhesion Dynamics and Cell Migration by Regulating SOCE in Osteosarcoma.

The dysregulation of store-operated Ca2+ entry (SOCE) promotes cancer progression by changing Ca2+ levels in the cytosol or endoplasmic reticulum. Stromal interaction molecule 1 (STIM1), a component of SOCE, is upregulated in several types of cancer and responsible for cancer cell migration, invasion, and metastasis. To explore the impact of STIM1-mediated SOCE on the turnover of focal adhesion (FA) and cell migration, we overexpressed the wild-type and constitutively active or dominant negative variants of STIM1 in an osteosarcoma cell line. In this study, we hypothesized that STIM1-mediated Ca2+ elevation may increase cell migration. We found that constitutively active STIM1 dramatically increased the Ca2+ influx, calpain activity, and turnover of FA proteins, such as the focal adhesion kinase (FAK), paxillin, and vinculin, which impede the cell migration ability. In contrast, dominant negative STIM1 decreased the turnover of FA proteins as its wild-type variant compared to the cells without STIM1 overexpression while promoting cell migration. These unexpected results suggest that cancer cells need an appropriate amount of Ca2+ to control the assembly and disassembly of focal adhesions by regulating calpain activity. On the other hand, overloaded Ca2+ results in excessive calpain activity, which is not beneficial for cancer metastasis.

Varifocal augmented reality adopting electrically tunable uniaxial plane-parallel plates.

Vergence-accommodation conflict (VAC) is a major challenge in optical-see through augmented reality (AR) system. To resolve this conflict, many approaches are proposed, for instance, by means of adjustment of the projected virtual image to coincide with the surroundings, called image registration, which is more often referred to as varifocal function. In this paper, a varifocal AR system is demonstrated by adopting electrically tunable liquid crystal (LC) plane-parallel plates to solve VAC problem. The LC plates provide electrically tunable optical paths when the directors of LC molecules are re-orientated with applied voltages, which leads to a corresponding change of light speed for an extraordinary wave. To provide a sufficient tunable optical path, three pieces of multiple-layered LC structures are used with the total thickness of the active LC layers (∼510 µm). In experiments, the projected virtual image can be adjusted from 1.4 m to 2.1 m away from the AR system, while the thickness of LC plane-parallel plates are only less than 3 mm without any mechanical moving part. When light propagates in the uniaxial LC layers, the wave vector and the Poynting vector are different. The longitudinal displacement of the image plane is determined by Poynting vectors rather than wave vectors. As a result, the analysis of the AR system should be based on Poynting vectors during geometrical optical analysis. Surprisingly, the tunable range of the longitudinal displacement of Poynting vectors is 2-fold larger than the tunable range of the wave vectors. Moreover, the virtual image shifts in opposite directions with respect to the Poynting vectors and wave vectors. The proposed AR system is not only simple but also thin, and it exhibits a large clear aperture. The investigation here paves the way to a simple solution of the VAC problem for augmented reality systems.

Polarization aberrations of electrically tunable liquid crystal mirrors.

Curved mirrors are able to fold optical paths and play important roles in compact optical systems in general. In this paper, we investigate the polarization aberrations of electrically tunable liquid crystal (LC) mirrors with two kinds of configurations (flat and curved ones). The LC mirrors exhibit spatially-continuous tunable wavefronts. The detailed wavefronts of two LC mirrors are related to angles of incidence, polarization of light, and the alignment direction of LC molecules. The key contribution of this paper is the development and characterization of a tunable liquid crystal mirror. The tunability of polarization aberration of LC mirrors should be able to provide extra parameters for optical engineers to design versatile optical systems.

Phase modulators with tunability in wavefronts and optical axes originating from anisotropic molecular tilts under symmetric electric field II: experiments.

We demonstrate, for the first time, an electrically-tunable and physically-planar freeform optical element made up of nematic liquid crystals (LCs). Continued on numerical study in previous paper (Part I), experimental results here show that it is possible to break the rotational symmetry of the wavefront through the use of uneven tilt angles of the LC molecules even though the electric potential is rotationally symmetric. Our optical element offers the ability to electrically tune the direction of the optical axis, the wavefront deviation, as well as the Zernike polynomials for general descriptions of wavefronts. Corresponding Zernike coefficients of a Zernike polynomial that are related to defocus and spherical aberration, which can be adjusted individually or together. The minimum wavefront deviation is >λ/6. The Zernike coefficients related to coma aberration or the tilt of the optical axis are also electrically tunable. By incorporating our LC phase modulator with tunability of freeform wavefronts into a simple reflective optical system, we demonstrate convincing image performance for off-axis image aberration correction. This approach will inspire further development and design of LC optical elements for applications, such as hyperspectral imagers in aerospace optics, augmented reality, virtual reality, quantum information systems, innovative miniaturized reflective telescopic systems for astrophysics, planetary science, and earth science.

Chemoresistant ovarian cancer enhances its migration abilities by increasing store-operated Ca2+ entry-mediated turnover of focal adhesions.

BACKGROUND: Among gynecological cancers, ovarian carcinoma has the highest mortality rate, and chemoresistance is highly prevalent in this cancer. Therefore, novel strategies are required to improve its poor prognosis. Formation and disassembly of focal adhesions are regulated dynamically during cell migration, which plays an essential role in cancer metastasis. Metastasis is intricately linked with resistance to chemotherapy, but the molecular basis for this link is unknown. METHODS: Transwell migration and wound healing migration assays were used to analyze the migration ability of ovarian cancer cells. Real-time recordings by total internal reflection fluorescence microscope (TIRFM) were performed to assess the turnover of focal adhesions with fluorescence protein-tagged focal adhesion molecules. SOCE inhibitors were used to verify the effects of SOCE on focal adhesion dynamics, cell migration, and chemoresistance in chemoresistant cells. RESULTS: We found that mesenchymal-like chemoresistant IGROV1 ovarian cancer cells have higher migration properties because of their rapid regulation of focal adhesion dynamics through FAK, paxillin, vinculin, and talin. Focal adhesions in chemoresistant cells, they were smaller and exhibited strong adhesive force, which caused the cells to migrate rapidly. Store-operated Ca2+ entry (SOCE) regulates focal adhesion turnover, and cell polarization and migration. Herein, we compared SOCE upregulation in chemoresistant ovarian cancer cells to its parental cells. SOCE inhibitors attenuated the assembly and disassembly of focal adhesions significantly. Results of wound healing and transwell assays revealed that SOCE inhibitors decreased chemoresistant cell migration. Additionally, SOCE inhibitors combined with chemotherapeutic drugs could reverse ovarian cancer drug resistance. CONCLUSION: Our findings describe the role of SOCE in chemoresistance-mediated focal adhesion turnover, cell migration, and viability. Consequently, SOCE might be a promising therapeutic target in epithelial ovarian cancer.

Prediction Model for Audiological Outcomes in Patients With GJB2 Mutations.

OBJECTIVES: Recessive mutations in GJB2 are the most common genetic cause of sensorineural hearing impairment (SNHI) in humans. SNHI related to GJB2 mutations demonstrates a wide variation in audiological features, and there has been no reliable prediction model for hearing outcomes until now. The objectives of this study were to clarify the predominant factors determining hearing outcome and to establish a predictive model for SNHI in patients with GJB2 mutations. DESIGN: A total of 434 patients confirmed to have biallelic GJB2 mutations were enrolled and divided into three groups according to their GJB2 genotypes. Audiological data, including hearing levels and audiogram configurations, were compared between patients with different genotypes. Univariate and multivariate generalized estimating equation (GEE) analyses were performed to analyze longitudinal data of patients with multiple audiological records. RESULTS: Of the 434 patients, 346 (79.7%) were homozygous for the GJB2 p.V37I mutation, 55 (12.7%) were compound heterozygous for p.V37I and another GJB2 mutation, and 33 (7.6%) had biallelic GJB2 mutations other than p.V37I. There was a significant difference in hearing level and the distribution of audiogram configurations between the three groups. Multivariate GEE analyses on 707 audiological records of 227 patients revealed that the baseline hearing level and the duration of follow-up were the predominant predictors of hearing outcome, and that hearing levels in patients with GJB2 mutations could be estimated based on these two parameters: (Predicted Hearing Level [dBHL]) = 3.78 + 0.96 × (Baseline Hearing Level [dBHL]) + 0.55 × (Duration of Follow-Up [y]). CONCLUSION: The baseline hearing level and the duration of follow-up are the main prognostic factors for outcome of GJB2-related SNHI. These findings may have important clinical implications in guiding follow-up protocols and designing treatment plans in patients with GJB2 mutations.

An optical system for augmented reality with electrically tunable optical zoom function and image registration exploiting liquid crystal lenses.

An optical-see-through augmented reality (AR) system assists our daily work by augmenting our sense with computer-generated information. Two of optical challenges of AR are image registration and vision correction due to fixed optical properties of the optical elements of AR systems. In this paper, we demonstrated an AR system with optical zoom function as well as a function of image registration via two LC lenses in order to help people see better by magnifying the virtual image and adjusting the location of virtual image. The operating principles are introduced, and experiments are performed. The concept demonstrated in this paper could be further extended to other electro-optical devices as long as the devices exhibit the capability of phase modulations.

Electrically tunable gradient-index lenses via nematic liquid crystals with a method of spatially extended phase distribution.

The dilemma between tunable range of a lens power and an aperture size in gradient-index (GRIN) type of liquid crystal (LC) lenses is well known due to the limitation of birefringence of LC martials and the nature of soft matters. In order to overcome the dilemma of the power law, a multi-layered LC lens was previously proposed by us. However, the aperture size of GRIN LC lenses is still difficult to exceed 10 mm. In this paper, we proposed an electrically tunable GRIN LC lens via nematic liquid crystals with a method of spatially extended phase distribution. A GRIN LC lens with an aperture size of 20 mm is achieved. The proposed GRIN LC lens consists of two LC elements modulating wavefronts at different regions of the lens aperture extending to 20 mm. The lens power of the GRIN LC lens is continuously tunable, while the LC lens can function as a positive lens, a negative lens, and a bifocal lens. The proposed GRIN LC lens not only overcomes the dilemma of the power law but also provides a more practical approach that could benefit the ophthalmic applications and augmented reality systems.

Liquid crystal beyond displays: feature introduction.

The editors introduce the feature issue on liquid crystal beyond displays.

Flexible light valves using polymer-dispersed liquid crystals and TiO2/Ag/TiO2 multilayers.

The era of flexible optoelectronics demands development of wearable and bendable structures, foldable touch screens, paper-like displays, and curved and flexible solid-state lighting devices. Here, we demonstrate the fabrication of highly flexible light valves using polymer-dispersed liquid crystal (PDLC) and TiO2/Ag/TiO2 transparent conductive films. TiO2/Ag/TiO2 multilayers were prepared by magnetron sputtering technique on polyethylene terephthalate (PET) substrates at room temperature. By keeping the equivalent TiO2 layers and varying the deposition time of the Ag layer, proper metal nanograins on TiO2 planar plane were formed, providing the best tradeoff between the transmittance, sheet resistance and bending ability. The results are validated by numerical simulations that suggest the best match between the deposition time and individual layer thickness. Based on the performed characteristics of TiO2/Ag/TiO2/PET structures, several flexible light valves are fabricated and characterized. The sheet resistance values of TiO2/Ag/TiO2/PET remain unchanged over 1000 bending cycles. The measured driving voltage and response time values open great potential of TiO2/Ag/TiO2/PET for integration into next-generation ITO-free flexible and stretchable devices.