Transparent Phase Research Articles

Quantitative phase analysis of transparent phase objects in a radial shearing interferometer incorporating a wire-grid polarizer

Quantitative phase analysis of transparent phase objects in a radial shearing interferometer incorporating a wire-grid polarizer

Cell classification with phase-imaging meta-sensors.

The development of photonic technologies for machine learning is a promising avenue toward reducing the computational cost of image classification tasks. Here we investigate a convolutional neural network (CNN) where the first layer is replaced by an image sensor array consisting of recently developed angle-sensitive metasurface photodetectors. This array can visualize transparent phase objects directly by recording multiple anisotropic edge-enhanced images, analogous to the feature maps computed by the first convolutional layer of a CNN. The resulting classification performance is evaluated for a realistic task (the identification of transparent cancer cells from seven different lines) through computational-imaging simulations based on the measured angular characteristics of prototype devices. Our results show that this hybrid optoelectronic network can provide accurate classification (>90%) similar to its fully digital baseline CNN but with an order-of-magnitude reduction in the number of calculations.

Wavefront sensing with a gradient phase filter

Wavefront sensors have now become core components in the fields of metrology of optical systems, biomedical optics, and adaptive optics systems for astronomy. However, none of the designs used or proposed so far achieve simultaneously a high spatial resolution at the pupil of the tested optics and absolute measurement accuracy comparable to those of modern laser-interferometers. This paper presents an improved wavefront sensor concept that reaches both previous goals. This device named Crossed-sine phase sensor (CSPS) is based on a fully transparent gradient phase filter (GPF) placed at an intermediate location between the virtual pupil and image planes of the tested optics. The theoretical principle of the sensor is described in Fourier optics formalism. Numerical simulations confirm that a measurement accuracy of λ/100 RMS is achievable. The CSPS also offers the advantages of being quasi-achromatic and working on spatially or spectrally extended, natural or artificial light sources.

Phase Engineering on MoS2 to Realize Dielectric Gene Engineering for Enhancing Microwave Absorbing Performance

AbstractPolarization relaxation loss caused by defects and interfaces has become a fascinating electromagnetic wave (EMW) loss mechanism. However, the logical relationship between impedance matching and various loss mechanisms requires further elucidation to facilitate more comprehensive and in‐depth research. Herein, phase engineering on molybdenum disulfide (MoS2) is proposed as the main controller of permittivity, offering a straightforward and highly effective method for regulating permittivity. Through the main control of phase engineering, a small gradient, monotonic change of the permittivity across a substantial area is achieved, leading to the gradual transition of the material system from strong loss but impedance mismatching to weak loss but EMW transparent phase. Thanks to the fundamental regulation of impedance characteristic and attenuation capacity by the dielectric gene engineering controlled by the phase engineering, combined with the ingenious coordination of sulfur vacancy‐induced polarization and interfacial polarization, t‐60 harvests an effective absorption band of 6.8 GHz and a minimum reflection loss of −59.8 dB. This study effectively expands the dielectric gene pool and improves the research logic for various loss mechanisms, offering valuable insights for the development of advanced EMW absorbing materials.

Subtomographic imaging of a polarisation sensitive phase pattern localised in phase space

A transparent polarisation-sensitive phase pattern changes the phase of transmitted light without absorption, whereas this change of phase depends on the polarisation of incident light. A position-localised polarisation-dependent phase pattern is imprinted onto the phase-space of atoms by using atomic state dependent velocity-selective hole burning. A phase-space localised pattern is a higher dimensional generalisation of patterns localised in the position-space. Such a pattern cannot be imaged with a lens. The imprinted pattern is localised in a unique three-dimensional subspace of the six-dimensional phase-space of atoms. The phase-space localised pattern transforms the polarisation of light transmitting through it. This pattern is tomographically imaged at room temperature by measuring the intensity of the transmitted imaging laser beam of variable frequency with a camera after its polarisation analysis. Two sub-tomographs of the imprinted phase-space localised pattern are constructed. This paper presents a concept and experiment of imprinting and imaging of a polarisation-sensitive phase pattern localised in the phase-space.

Electrically-switched differential microscopy based on computing liquid-crystal platforms

Abstract Detection of transparent phase specimens especially biological cells with desired contrasts is of great importance in visual display and medical diagnosis. Due to the pure-phase nature, conventional detection approaches may damage samples or require complex operations. Computing liquid crystal (LC) is a thin and flat optical element with excellent capability in optical field modulation, which gives a feasible way to this issue from the perspective of analog optical computing. We here propose and experimentally implement an electrically switched two-dimensional (2D) differential microscopy based on computing LC platforms. The Pancharatnam–Berry phase LC polarization grating induces light’s spin separation to promote the 2D differential operation. Using the electrically tunable LC plate as the system phase retardance provider, the detecting mode can be flexibly switched from bright-field images to edge-enhanced images with desired contrasts. Remarkably, owing to the wavelength-independent feature closely related to the geometric phases, our proposed scheme is demonstrated to be applicable to the multi-wavelength microscopy imaging. These results open avenues to form real-time all-optical image processing and may facilitate multifunctional differential microscopy.

Clinical features relating to pneumococcal colony phase variation in hospitalized adults with pneumonia.

Background. Streptococcus pneumoniae is a major causative bacteria of pneumonia and invasive pneumococcal disease (IPD); however, the mechanisms underlying its severity and invasion remain to be defined. Pneumococcal colonies exhibit opaque and transparent opacity phase variations, which have been associated with invasive infections and nasal colonization, respectively, in animal studies. This study evaluated the relationship between the opacity of pneumococcal colonies and the clinical presentation of pneumococcal pneumonia.Methods. This retrospective study included adult patients hospitalized with pneumococcal pneumonia between 2012 and 2019 at four tertiary medical institutions. Pneumococcal strains from lower respiratory tract specimens were determined for their serotypes and microscopic colony opacity, and the association between the opacity phase and the severity of pneumonia was evaluated. Serotypes 3 and 37 with mucoid colony phenotypes were excluded from the study because their colony morphologies were clearly different.Results. A total of 92 patients were included. Most patients were older adults (median age: 72 years) and males (67 %), and 59 % had community-acquired pneumonia. Of the 92 patients, 41 (45 %), 12 (13 %), and 39 (42 %) patients had opaque, transparent, and mixed variants in their pneumococcal colony, respectively. The opaque and non-opaque pneumococcal variants had no statistically significant difference in patient backgrounds. Although the pneumonia severity index score did not differ between the opaque and non-opaque groups, the rate of bacteremia was significantly higher in the opaque group than in the non-opaque group. Serotype distribution was similar between the groups.Conclusions. Opaque pneumococcal variants may cause pneumonia and invasive diseases in humans. This study could help elucidate IPD, and opacity assessment may serve as a predictor for IPD.

A day-night solar thermoelectric generator enabled by phase change material and forced water cooling

Solar thermoelectric generators (STEGs), which are capable of directly converting solar energy to electricity, are essential to many potential applications in addition to photovoltaics. It is of great importance to advance the design of STEGs to significantly boost the output performance by combining solar selective absorbers, cooling technologies and phase change materials. In this work, a novel day-night STEG integrated with transparent phase change materials of methyl palmitate and forced water cooling (PCM-STEG-WC) is proposed. The fabricated solar selective absorber exhibits a high solar absorption of 96.05 %, leading to its surface temperature up to 100 °C under 1-sun illumination (1 kW m−2), while the surface temperature of conventional thermoelectric module is only about 44.4 °C. Consequently, the temperature difference between hot and cold ends can be significantly increased to 5.6 °C from 2 °C, about 2.8 times higher than the conventional thermoelectric module. Moreover, this unconcentrated PCM-STEG-WC can realize a power level of 6.42 mW associated with output voltage of 307.3 mV at a solar density of 1 kW m−2, which is about 9 times higher than that of conventional thermoelectric module (35.5 mV). Additionally, the hot end temperature of PCM-STEG-WC only decays by 17 % in 100 s without solar radiation. To demonstrate the effectiveness of the PCM-STEG-WC in power generation at night, a single red LED is completely powered. Finally, this study may provide a promising strategy to develop high-performance STEGs for remote applications.

Amine Gas-Induced Reversible Optical Bleaching of Bismuth-Based Lead-Free Perovskite Thin Films.

Reversible optical property changes in lead-free perovskites have recently received great interest due to their potential applications in smart windows, sensors, data encryption, and various on-demand devices. However, it is challenging to achieve remarkable color changes in their thin films. Here, methylamine gas (CH3 NH2 , MA0 ) induced switchable optical bleaching of bismuth (Bi)-based perovskite films is demonstrated for the first time. By exposure to an MA0 atmosphere, the color of Cs2 AgBiBr6 (CABB) films changes from yellow to transparent, and the color of Cs3 Bi2 I9 (CBI) films changes from dark red to transparent. More interestingly, the underlying reason is found to be the interactions between MA0 and Bi3+ with the formation of an amorphous liquefied transparent intermediate phase, which is different from that of lead-based perovskite systems. Moreover, the generality of this approach is demonstrated with other amine gases, including ethylamine (C2 H5 NH2 , EA0 ) and butylamine (CH3 (CH2 )3 NH2 , BA0 ), and another compound, Cs3 Sb2 I9 , by observing a similar reversible optical bleaching phenomenon. The potential for the application of CABB and CBI films in switchable smart windows is investigated. This study provides valuable insights into the interactions between amine gases and lead-free perovskites, opening up new possibilities for high-efficiency optoelectronic and stimuli-responsive applications of these emerging Bi-based materials.

In Situ Formation of a Relatively Transparent Ion-Associate Liquid Phase from an Aqueous Phase and Its Application to Microextraction/High-Performance Liquid Chromatography-Fluorescence Detection of Bisphenol A in Water.

The design of a simple approach enabling the detection of bisphenol A (BPA) in water samples without the need for large amounts of solvents is of utmost importance. This paper reports a simple method for the separation, concentration, and quantification of BPA in water samples using high-performance liquid chromatography with fluorescence detection (HPLC-FLD) after its microextraction into an in situ formed organic ion-associate (IA) liquid phase (LP). Novel IA phase components without conjugated double bonds, such as benzene rings, were investigated. Ethylhexyloxypropylamine hydrochloride and sodium dodecyl sulfate solutions were added to the water samples to form IAs. The aqueous phase and ion-associate liquid phase (IALP) were separated by centrifugation. The aqueous phase was removed, and the liquid phase was recovered and measured using HPLC-FLD or HPLC-electrochemical detection (ECD). The concentrated phase (IALP) had a relatively low viscosity and could be injected directly into the chromatograph without dissolving it in organic solvents. The detection limits for BPA by HPLC-FLD and HPLC-ECD were 0.009 and 0.3 µg L-1, respectively.

Surface topography detection based on an optical differential metasurface.

Surface topography detection can extract critical characteristics from objects, playing an important role in target identification and precision measurement. Here, an optical method with the advantages of low power consumption, high speed, and simple devices is proposed to realize the surface topography detection of low-contrast phase objects. By constructing reflected light paths, a metasurface can perform spatial differential operation via receiving the light directly reflected from a target. Therefore, our scheme is experimentally demonstrated as having remarkable universality, which can be used not only for opaque objects, but also for transparent pure phase objects. It provides a new, to the best of our knowledge, application for optical differential metasurfaces in precise detection of microscale surface topography.

RCS reduction of composite transparent flexible coding metasurface combined phase cancellation and absorption.

A wideband low-scattering metasurface with optical transparency and flexibility is proposed by using the combination of phase cancellation and absorption mechanisms. Electromagnetic (EM) diffusion is achieved through the random phase distribution design of the two coding elements. The enhanced energy absorption can be obtained in a wide spectrum by using indium tin oxide (ITO) with suitable sheet resistance in the supercells. The experimental results show that the radar cross section (RCS) reductions of less than -10 dB under the planar and conformal cases are in 6.65-19.40 GHz and 6.11-17.37 GHz, corresponding relative bandwidth are 97.89% and 95.91%, respectively. Both theoretical analysis and simulated results are good accordance with the experiment. Furthermore, the analyses of the surface current, EM field distribution and power loss density are given to explain the hybrid RCS reduction mechanism. The proposed composite transparent flexible coding metasurface (CTFCM) maintains good angular stability within 0°-60° oblique incidence and has polarization insensitivity. The CTFCM has excellent flexibility and high optical transparency, which provides a way to reduce RCS in a wider band and has important application potential for stealth aircraft cockpit and transparent radome.

QTPI: A quasi-toxicity probability interval design for phase I trials with multiple-grade toxicities.

The common terminology criteria for adverse events by the National Cancer Institute has greatly facilitated the revolution of drug development and an increasing number of Phase I trials have started to collect multiple-grade toxicity endpoints. Appropriate and yet transparent Phase I statistical designs for multiple-grade toxicities are therefore in great needs. In this article, we propose a quasi-toxicity probability interval (qTPI) design that incorporates a quasi-continuous measure of the toxicity probability () into the Bayesian theoretic framework of the interval based designs. Multiple-grade toxicity outcomes of each patient are mapped to according to a severity weight matrix. Dose-toxicity curve underlying the dosing decisions in the qTPI design is continuously updated using accumulating trial data. Numerical simulations investigating the operating characteristics of qTPI show that qTPI achieved better safety, accuracy and reliability compared to designs that rely on binary toxicity data. Furthermore, parameter elicitation in qTPI is simple and does not involve multiple hypothetical cohorts specification. Finally, a hypothetical soft tissue sarcoma trial with six toxicity types and grade 0 to grade 4 severity grades is illustrated with patient-by-patient dose allocation under the qTPI design.

基于CsPbIBr2的全无机半透明器件的光伏性能与热 致变色性能

The photovoltaic thermochromic smart window, which combines perovskite with thermochromic and photovoltaic properties, can not only control the solar transmittance at different temperatures, but also convert the absorbed light energy into usable electric energy. Herein, we designed a fluoride-doped tin oxide (FTO)/SnO2/CsPbIBr2/NiOx/indium tin oxide (ITO) semitransparent solar cell structure by using the optimized post-annealing process and obtained an average visible transmittance (AVT) of 33.2% and a power conversion efficiency of 3.89% under the optimal conditions. Meanwhile, based on the thermochromic properties of CsPbIBr2, it was found that the AVT of the device improved from 33.2% to 73.5% when CsPbIBr2 converted from the colored high-temperature phase to the transparent low-temperature phase. Besides, the transition from high-temperature phase to low-temperature phase is humidity-dominated. When the relative humidity rises from 50% to 90%, the phase transition time of perovskite decreases substantially from 1005 to 17 min. However, the excessively fast phase transition caused by high humidity will destroy the thin film morphology and crystal structure of perovskite, causing irreversible damage to CsPbIBr2 perovskite. This work is promising for the application of semitransparent photovoltaic and thermochromic smart window, which represents an attractive prospect in further reducing the energy consumption of buildings and automobiles.

Effect of Phase Change Materials on the Optical Path of LEDs for Opto-Thermal Enhancement

A novel concept based on the encapsulation of transparent phase change materials (PCMs) into the optical packaging structure of light-emitting diodes (LEDs) is presented in this article. The concept was initiated by challenges of thermal management of photoluminescent particles in high-power optical systems. LEDs, white LEDs (WLEDs), and porous/network-based photoluminescent matrices can achieve improved thermal networks by embedding PCMs. In this article, paraffin is selected as a suitable PCM encapsulant, and aside from thermal perspectives, an unexpected optical benefit with melted paraffin after surface wetting of the chip was observed. Immersing an LED chip in a melted paraffin pool showed up to an 8% increase in light extraction efficiency and a 1.5% increase in power conversion efficiency (PCE). An accurate dynamic opto-electro-thermal monitoring of studied devices was used to support the proof of concept. This viable method can be integrated into current industrial packaging processes.

Inversion of extinction coefficient and refractive index of variable transparency solid–solid phase change material based on a hybrid model under real climatic conditions

The application of phase change materials (PCMs) in transparent building envelopes has received extensive attention. However, most of the studies have simplified the optical parameters of the PCMs in their models. Because the temperature of PCMs cannot be controlled when using the spectrophotometer, it is difficult to measure the changing trend of optical parameters versus temperature. In this study, an inverse approach was developed for the first time, based on a hybrid model, to fit the accurate function expressions between the extinction coefficient and the refractive index of PCM and temperature. The hybrid model was a combination of experimental data-driven, mathematical models, and multi-objective optimization. Firstly, a test platform of the variable transparency solid–solid PCM (VTSS-PCM) window was constructed and tested last for a year to collect the datasets. Secondly, the photo-thermal coupling model of the window was established, in which the hysteresis and the total internal reflection phenomena were considered. Then, taking the unknown coefficients in the function expressions as decision variables, a bi-objective optimization model was built, based on two error statistics of experimental values and simulated values, and solved by genetic algorithm. Finally, the inversion dataset and validation dataset were used to prove the reliability of the inversion results. The results showed that the refractive index and extinction coefficient of the VTSS-PCM were 1.11 and 25.73 m−1 in the transparent phase, and 5.33 and 152.82 m−1 in the opaque phase. Within the phase change temperature range, the function expressions between the refractive index and extinction coefficient and the temperature were obtained respectively. The verification results showed that the function curves obtained by inversion were reliable. No matter whether the inversion dataset or validation dataset was used as input, the values of RMSE and CV(RMSE) met the ASHRAE Guidelines. The inversion method is meaningful to get the optical parameters of PCMs, to accurately evaluate the performance of PCM-built envelope.

Optimization of the Brewing Process and Analysis of Antioxidant Activity and Flavor of Elderberry Wine

Fruit wines have high nutritional value and good palatability. However, fruit wine made from a single fruit type does not have good enough flavor and nutritional quality. Therefore, flavorsome fruit wines made from a variety of fruits should be developed as a matter of urgency. In this study, the raw material of elderberry wine was used to explore the production technology of mixed juice wines; the fruits selected were apple, lychee, pear, blueberry, and elderberry. We utilized a single-factor experiment and the response surface method (RSM) approach to optimize the fermentation procedures; the results show that the solid–liquid ratio was 1:7.5, the amount of yeast inoculation was 0.68 g/L, the fermentation temperature was 20 °C, and the added sugar content was 120 g/L. Under these process conditions, a verification test was carried out in a 35 L fermenter. The results showed that the alcohol content, residual sugar content, total acidity, total phenol content, and total flavonoid content of the elderberry wine were, respectively, 7.73% vol, 8.32 g/L, 9.78 g/L, 8.73 mg/mL, and 1.6 mg/mL. In total, 33 volatile components were identified in the resulting elderberry wine. It achieved a harmonious aroma and fruit flavor, a homogeneous and transparent liquid phase, a pleasant taste, and a sensory evaluation score of 95. The antioxidant activity experiments showed that elderberry had a certain antioxidant capacity, and that fermented elderberries had significantly higher antioxidant ability than unfermented ones.

Highly transparent, superhydrophilic and high-temperature stable anatase phase TiO2

Stable anatase phase of TiO2 above 700 °C plays a very important role in the fields of photocatalysis, antibacterial, self-cleaning and solar cells etc. However, the stabilization of the anatase phase of TiO2 at higher temperatures has been very challenging so far. Here, we report a glancing angle deposition (GLAD) employing e-beam evaporation to fabricate slanted nanorods, vertical nanorods, and zig-zag nanorods of TiO2, which show the stabilization of the anatase phase up to 1000 °C. The amorphous nature of the substrate and least oxygen vacancy in the TiO2 are found to be the major cause for the thermal stabilization of the anatase phase. All annealed samples were found to be superhydrophilic when measured immediately after annealing, while the dark storage transforms the samples to hydrophilic. Nevertheless, UV exposure for 10 min reverted them to superhydrophilic. FTIR studies were performed on the samples to understand the role of surface hydrocarbons in the transition from hydrophobic to hydrophilic states. The samples show a transmittance ∼90% in the visible spectrum. The simultaneous existence of a highly transparent, superhydorphilic and high temperature stable anatase TiO2 can give a boost to several fields e.g., smart windows/doors, self-cleaning coatings, etc.

Исследование пленок оксида кремния, имплантированных цинком

This paper presents the results of studying the composition, structure, and properties of amorphous SiO x film obtained by electron beam evaporation. This film was implanted by Zn ions with energy of 40 keV and a dose of 3×10 16 /cm 2 . Then, annealing was carried out in air at temperatures from 400 to 800°C with a step of 100°C for 1 hour at each stage. It has been found that, after implantation, metal Zn nanoclusters with a size of about 10 nm are formed on the surface and in the near-surface layer of silicon oxide. During annealing, the implanted layer becomes clear, since metallic Zn gradually oxidizes to transparent phases of its oxide ZnO and silicide Zn 2 SiO 4 . After annealing at 700°C, ZnO nanoclusters and surface craters were revealed on the surface and in the subsurface layer of the SiO 2 film.

On the Use of Haloalkane/Acrylate-Based Holographic Gratings as Compression and Rotation Sensors.

In this work, we test the effectiveness of using highly transparent holographic phase reflection and transmission volume gratings based on multifunctional acrylates as linear compression and rotation sensors. The gratings are recorded in a holographic mixture based on multi-reticulated acrylate and haloalkanes. To activate the photo-polymerization process, we used a mixture of 6-oxocamphore and rhodamine 6G. The mixture is a simplified version of the mixture used in previous works and shows some interesting features mainly in connection with the different roles played by the rhodamine 6G dye at different writing wavelengths λ = 532 nm and λ = 460 nm. Regarding reflection gratings, the maximum achieved diffraction efficiency is ≈50% and their use as linear compression sensors produces a shift in the reflection peak of 2 nm. Following the removal of compression, the grating slowly returns to the initial state. Regarding transmission gratings, the maximum achieved diffraction efficiency is ≈45% and they demonstrate very high sensitivity to even small rotations in a free-standing configuration.