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Oxygen is a ubiquitous contaminant in thin films grown in high vacuum systems, and it was hypothesized to play an important role in the properties of the p -type conductivity of transparent copper(I) iodide, CuI. We study the ambient properties of CuI deposited at various partial pressures of oxygen gas. Through a variety of experimental techniques, we find that achieving a critical oxygen partial pressure of below p(O2) = 3 × 10 − 5 mbar is essential for depositing stoichiometric and conductive CuI thin films. Notably, we relate the commonly reported copper excess to the presence of oxygen within the CuI films. Notably, we relate the commonly reported excess of copper in CuI thin films to to the presence of oxygen. Finally, we infer from transport and optical measurements that the hole transporting properties of sputtered CuI films are dominated by an abundance of VCu defects with an acceptor transition energy of 84 ± 3 meV rather than OI defects with an acceptor transition energy of 175 ± 14 meV. [ABSTRACT FROM AUTHOR]

Skin expansion is a well-established technique in plastic surgery, and recent studies have highlighted its potential in promoting hair regeneration. This study aimed to explore how the mechanical and optical properties of skin change during a prolonged stretching process. A hybrid method was developed to assess, in vivo, the effects of an 8-day skin stretching protocol—previously used in hair regeneration research—on the dorsal skin of mice. This method combined mechanical and optical measurement systems. Tensile stress–strain curves were generated using a spring-based setup, while optical properties such as scattering and birefringence were analyzed with a polarimetry imaging system that incorporated the Mueller matrix (MM) and Mueller matrix polar decomposition (MMPD) methods. The results showed that Young's modulus increased from approximately 5 kPa on day 1 to 60–100 kPa by days 6–8, indicating collagen fiber straightening and increased stiffness. Optical analysis revealed greater anisotropy in both scattering and birefringence, as reflected by changes in MM elements and MMPD results. These changes suggest skin adaptation and regeneration, particularly within the first 24 h of stretching. Interestingly, alterations in optical properties closely mirrored changes in mechanical properties, pointing to a coordinated process of structural remodeling and functional adaptation in the skin. These findings offer valuable insights into skin remodeling and adaptation, which could guide future tissue engineering strategies. [ABSTRACT FROM AUTHOR]

The interfacial local field is of critical importance in data analysis to deduce intrinsic surface responses from optical measurements of interfaces of condensed media but has not yet been well interrogated. We present here a simple approach to find local fields approximately at various interfaces of isotropic or nearly isotropic media. We divide a medium into atomic planes or molecular layers. It is found that the dipolar field contribution to the local field in a plane or layer from induced dipoles residing in planes beyond the nearest neighbor planes or layers is negligible; in many cases, the contribution is dominated by in-plane dipoles and the local field has a simple expression very much like that for an isotropic bulk. This finding allows us to calculate approximate local field variation at various interfaces. With the interfacial local field known, intrinsic surface response coefficients can be extracted from the optically measured surface responses. [ABSTRACT FROM AUTHOR]

Number density of plasma-generated atoms or molecules is an important parameter for both fundamental research and applications. It can be measured in a straightforward manner, using vacuum-ultraviolet absorption spectroscopy, which is mainly possible in laboratory conditions as it may require bulky equipment, such as lasers. By contrast, optical actinometry is an alternative approach that only uses spontaneous emission from the plasma. This technique relies on the so-called corona excitation and uses emission line ratios between the gases with unknown and known concentrations (called actinometer in the last case). As a result of using line ratios, the additional density calibration is not required if the excitation cross sections are known. This study discusses Ar-based actinometry in low-pressure (roughly < 1 kPa) plasma discharges with an emphasis on multiple line ratios. The work is particularly focused on the method's applicability, the choice of Ar cross sections, and potential error sources. The influence of the additional excitation mechanisms is analyzed based on both experiments and modeling. The optical transitions for F, O, H, N, and P atoms along with expressions for their number density are presented, not requiring high optical resolution for measurements. For the sake of method validation, it is shown that in low-pressure radiofrequency discharges, a nearly excellent agreement between the actinometry data and the calibrated measurements can be achieved by careful selection of optical transitions. [ABSTRACT FROM AUTHOR]

Polarization is one of the fundamental properties of light and has an important application value, involving multiple fields, such as imaging, display, quantum computing, and biosensing. The artificial metasurface can achieve comprehensive control of electromagnetic waves, such as amplitudes, phases, and polarization states. Compared to traditional optical devices, the metasurfaces have advantages, such as small size and diverse functions, meeting the needs of modern optical systems for ultra-lightweight, ultra-compact, and multifunctional optical components. Chiral media are widely presented in various macroscopic and microscopic systems in nature. Circular dichroism (CD) is commonly used to describe the difference in absorption rates of left-handed circularly polarized light and right-handed circularly polarized light in chiral media. However, the optical response of chiral media in nature is usually weak and mainly located in the ultraviolet band, which limits their detection sensitivity and practical application range. In this work, we proposed a chiral metasurface model with four rectangular holes with proper rotation. By rotating the rectangular or elliptical holes at a certain angle, the symmetry of the structure is disrupted, making it chiral. The proposed metasurface devices were fabricated, and the optical measurements were performed, which were in good agreement with the designs. The normalized CD values are around 0.01 at the near-infrared region. This work provides a complete procedure of the metasurface device and initials chiral-tunable flat meta-devices. It also has broad application prospects in fields, such as polarization imaging, life sciences, and drug chiral detection. [ABSTRACT FROM AUTHOR]

AlxGa1−xN epilayers are used as the basis of ultraviolet LEDs and detectors. The trap states produced by defects and impurities can play a key role in the device performance. In this work, conventional deep-level transient spectroscopy, photoluminescence (PL), and secondary ion mass spectrometry have been used to characterize a deep-level trap termed as E3 in dilute AlxGa1−xN (x < 0.063) epilayers grown by metal-organic vapor phase epitaxy (MOVPE) on highly conductive ammono-GaN substrates. The AlxGa1−xN epilayers were doped with silicon to about 3 × 1016 cm−3. The electrical and the optical measurements were conducted on Ni/Au Schottky barrier diodes and virgin samples, respectively. First, we observed a general trend that the E3 (FeGa) electron trap concentration significantly changes along the wafers in AlxGa1−xN layers that is fully consistent with previously reported results for GaN materials grown by the MOVPE technique. Second, we report that the activation energies for electron emission for the E1 and E3 traps in dilute AlxGa1−xN exhibit linear variations with Al content. Moreover, low-temperature PL results show a proportional relation between the intensity of the line with its maximum at 1.299 eV and concentration of residual Fe impurity. Finally, we discuss how the presence of defects resulting from Fe contamination may result in degradation of AlxGa1−xN-based devices. [ABSTRACT FROM AUTHOR]

Circular dichroism (CD) spectra for pseudo-two-dimensional chiral nanomaterials were systematically investigated and analyzed in relation to the rotational symmetry of the nanomaterials. Theoretically, an ideal two-dimensional chiral matter is CD inactive for light incident normal to the plane if it possesses threefold or higher rotational symmetry. If the matter has two- or onefold rotational symmetry, it should exhibit CD activity, and the CD signal measured from the back side of the matter is expected to be inverted from that measured from the front side. For pseudo-two-dimensional chiral gold nanostructures fabricated on glass substrates using electron beam lithography, matter with fourfold rotational symmetry is found to be CD active, even when special care is taken to ensure that the optical environments for the front and back sides of the sample are equivalent. In this case, the CD signal measured from the back side is found to be almost exactly the same as that measured from the front side. It is revealed that the observed chiro-optical behavior arises from three-dimensional chiral characteristics due to differences in the surface shape between the front and back sides of the structures. For matter that is two- or onefold rotationally symmetric, the CD signal measured from the back side is not coincident with that from the front side. For certain wavelength regions, the CD signals measured from the front side and back side are observed to be similar, while at other wavelengths, the inverted component of the CD signals is found to dominate. The observed CD spectral behavior for reciprocal optical measurement configurations is considered to be determined by a balance between the in-plane isotropic and anisotropic components of the chiral permittivity. [ABSTRACT FROM AUTHOR]

Photonic spin–orbit (SO) coupling is an important physical mechanism leading to numerous interesting phenomena in the systems of microcavity photons and exciton-polaritons. We report the effect of SO coupling in a tunable open-access microcavity embedded with anisotropic active media. The SO coupling associated with the TE–TM splitting results in an emergent anisotropy, which further leads to fine energy splittings allowing clear observation of the full set of eigenstates, in sharp contrast with the isotropic situation which leads to the isotropic eigenstates of spin vortices. We show that the photonic potential can be engineered by playing with the relation between the emergent anisotropy and the cavity ellipticity. All the experimental results are well reproduced by the degenerate perturbation theory. Our results constitute a significant extension to the research field of microcavity spinoptronics, with potential applications in polarization control and optical property measurement of photonic devices and materials. [ABSTRACT FROM AUTHOR]

Mechanisms of formation and losses of radiation belts are the most important questions of magnetospheric physics, especially in a subsecond temporal scale. Energetic particles release their energy in the atmosphere producing fluorescent emission in characteristic wavelength bands. This emission is measurable and can be an additional information source on the spatiotemporal structure of particle fluxes and spectra. Here we present the world's first measurements of UV-microbursts during geomagnetic disturbance and pulsating aurora caused by high-energy electron precipitation. It demonstrates that fundamental questions of magnetospheric physics mentioned above can be addressed by using the optical measurements by highly sensitive photometers with high temporal resolution. Such a photometer was installed at Verkhnetulomsky observatory at Kola Peninsula and measured a series of short (less than 0.5 s) pulses of emission with an angular size of bright spot ∼ 0.2 rad. Simultaneous measurements of high-energy electron fluxes made by the NOAA-19 satellite and fine temporal structure of geomagnetic pulsations demonstrate a magnetospheric origin of the observed events. [ABSTRACT FROM AUTHOR]

Optical techniques, such as functional near-infrared spectroscopy (fNIRS), contain high potential for the development of non-invasive wearable systems for evaluating cerebral vascular condition in aging, due to their portability and ability to monitor real-time changes in cerebral hemodynamics. In this study, thirty-six healthy adults were measured by single channel fNIRS to explore differences between two age groups using machine learning (ML). The subjects, measured during functional magnetic resonance imaging (fMRI) at Oulu University Hospital, were divided into young (age ≤ 32) and elderly (age ≥ 57) groups. Brain pulses were extracted from fNIRS using a single 830 nm wavelength. Four feature sets were derived from log-normal parameters estimated by pulse decomposition algorithm. ML experiments utilized support vector machines and random forest learners, along with maximum relevance minimum redundancy and principal component analysis for feature selection. Performance with increasing sample size was estimated using learning curve method. The best mean balanced accuracies for each feature set were over 75% (75.9%, 76.4%, 79.3%, 76.9%), indicating the pulse features containing age related information. Learning curves indicated stable classification performance with increasing sample size. The results demonstrate the potential of using single channel fNIRS in the analysis of aging. [ABSTRACT FROM AUTHOR]

The complex composition of seawater presents significant challenges for accurately estimating biogeochemical data through optical measurements, both in situ and via satellite data. To address the regional applicability of single bio-optical or remote sensing algorithms caused by these challenges, we explored a water optical classification method based on inherent optical properties and particle composition. The ratio of organic particulate matter to total suspended particulate matter concentration (POM/SPM) serves as an optical discriminator of water bodies based on the proportions of organic and mineral particles. The boundary value is determined by the relationship between the particulate backscattering coefficient bbp (λ) and POM/SPM. By analyzing in situ data collected from the coastal waters of Qinhuangdao in the Bohai Sea, China, we developed empirical algorithms to estimate both the POM/SPM ratio and chlorophyll-a (Chl-a) concentration, the latter being a key parameter derived from current ocean remote sensing that indicates phytoplankton abundance. The evaluation of our algorithms demonstrates that accounting for POM/SPM variations significantly improves Chl-a estimate accuracy across the optically-complex coastal waters near Qinhuangdao compared to algorithms that do not consider changes in particle composition, such as the well-known OC4Me algorithm. Furthermore, we determined the distribution of monthly averaged Chl-a concentration and POM/SPM ratio on the coast of Qinhuangdao, Bohai Sea, in 2023. Our results show, for the first time, that the monthly average variations of the POM/SPM ratio in the Bohai Sea and Chl-a concentrations exhibit pronounced seasonal fluctuations. [ABSTRACT FROM AUTHOR]

Novel Mn4+-activated Ba 2 LuSbO 6 (BLSO) red phosphor was synthesized by a high-temperature solid-state reaction method. A thorough investigation was conducted into its phase composition, crystal structure, elemental valence state, crystal field strength, quantum yield (QY), photoluminescence excitation (PLE) spectra, and photoluminescence (PL) emission spectra. Impressively, the addition of Na+ ions to BLSO: 0.5%Mn4+ phosphors dramatically increased the emission intensity and QY by enlarging the crystal field strength. The corresponding mechanisms were systematically studied. The dual-mode wide-range optical thermometers based on LIR (stokes vs. anti-stokes sideband) and fluorescence lifetime exhibited a maximum relative sensitivity of 1.41 % K−1@473 K and 1.1 % K−1@473 K, respectively. This phosphor has a potential application prospect in the field of wide-range optical temperature measurement. [ABSTRACT FROM AUTHOR]

The production of biodegradable and biobased polymers is one way to overcome the present plastic pollution while using cheap and abundant feedstocks. Polyhydroxyalkanoates are a promising class of biopolymers that can be produced by various microorganisms. Within the production process, batch-to-batch variation occurs due to changing feedstock composition when using waste streams, slightly different starting conditions, or biological variance of the microorganisms. Therefore, reliable and online-capable measurement methods of the product concentration are required to monitor and eventually react to those fluctuations. In this work, we present a flexible approach to determine polyhydroxyalkanoate concentrations based on a simple mathematical model. The data-driven model correlates polyhydroxyalkanoate concentrations with optical densities measured at 600 nm, a widespread, fast, and cheap lab measurement. We found that with different cultivation conditions, the correlation needs to be updated for a reasonable PHA determination during the process. We test this approach for the production of poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in Cupriavidus necator using fructose and propionic acid as carbon sources. This flexible approach allows a simple estimation of PHA concentrations and offers the possibility to further enhance biopolymer production when combined with advanced control strategies. Key points: ∙ Development of a simple mathematical model to estimate polyhydroxyalkanoate concentrations. ∙ Optical density measurement is used to determine polyhydroxyalkanoate concentration. ∙ The approach is tested for the production of PHB and PHBV with C. necator. [ABSTRACT FROM AUTHOR]

Cellular structures are increasingly utilized in modern engineering due to their exceptional mechanical and physical properties. In this study, the deformation and failure mechanisms of two energy-efficient lattice structures—hexagonal honeycomb and re-entrant honeycomb—were investigated. These structures were manufactured using additive stereolithography with light-curable Durable Resin V2. The experimental testing of the topologies under two perpendicular loading directions employed the 3D Digital Image Correlation (DIC) system to capture strain fields and deformation patterns, providing insights into structural behavior and failure mechanisms. The unit cells of the topologies were scaled up to enable precise optical measurements while preserving their structural interaction characteristics. Numerical simulations, conducted using the SAMP-1 material model in LS-DYNA and calibrated with tensile and compression test data, accurately replicated the behavior of the studied topologies and demonstrated good agreement with experimental results. The hexagonal structure, loaded along axis 2, showed the best fit, with deviations within 5%, while the re-entrant honeycomb structure exhibited weaker yet reasonable agreement. By integrating experimental and numerical approaches, the research validates the SAMP-1 model's predictive capabilities for lattice structures and provides a framework for analyzing energy-absorbing lattice topologies. [ABSTRACT FROM AUTHOR]

Purpose: To investigate different measures for corneal astigmatism in the context of reconstructed corneal astigmatism (recCP) as required to correct the pseudophakic eye, and to derive prediction models to map measured corneal astigmatism to recCP. Methods: Retrospective single centre study of 509 eyes of 509 cataract patients with monofocal (MX60P) IOL. Corneal power measured with the IOLMaster 700 keratometry (IOLMK), and Galilei G4 keratometry (GK), total corneal power (TCP2), and Alpin's integrated front (CorT) and total corneal power (CorTTP). Feedforward shallow neural network (NET) and linear regression (REG) prediction models were derived to map the measured C0 and C45 power vector components to the respective recCP components. Results: Both the NET and REG models showed superior performance compared to a constant model correcting the centroid error. The mean squared prediction errors for the NET/REG models were: 0.21/0.33 dpt for IOLMK, 0.23/0.36 dpt for GK, 0.24/0.35 for TCP2, 0.23/0.39 dpt for CorT and 0.22/0.36 dpt for CorTTP respectively (training data) and 0.27/0.37 dpt for IOLMK, 0.26/0.37 dpt for GK, 0.38/0.42 dpt for TCP2, 0.35/0.36 dpt for CorT, and 0.44/0.45 dpt for CorTTP respectively on the test data. Crossvalidation with model optimisation on the training (and validation) data and performance check on the test data showed a slight overfitting especially with the NET models. Conclusions: Measurement modalities for corneal astigmatism do not yield consistent results. On training data the NET models performed systematically better, but on the test data REG showed similar performance to NET with the advantage of easier implementation. [ABSTRACT FROM AUTHOR]

Linear plasmas, compared to small-area low-temperature plasma jets, offer a larger single-treatment area with a brush-like pattern, making them highly promising for various applications. This paper introduces the design of an adjustable low-temperature linear plasma source that operates under atmospheric pressure at 2.45 GHz. The design integrated microwave theory with dielectric barrier discharge principles, utilizing a resonant structure based on a microstrip power divider with one end open and the other shorted. The ground plane of the microstrip structure was replaced by a metal plate featuring a large groove. Argon gas was introduced from the short-circuited end and exited through the groove at the open end, where plasma excitation occurred. Experimental results demonstrated that the device, operating at atmospheric pressure, can achieve adjustable linear plasma widths ranging from 10 mm to 50 mm by varying the incident power between 30 and 100 W. Optical emission measurements confirmed the uniformity of the linear plasma, and the gas temperature 5 mm away from the discharge area remained at only 65 °C, even with a microwave incident power of 100 W. This study offers a novel approach to designing linear atmospheric pressure microwave plasma sources, with significant potential for diverse material treatment applications. [ABSTRACT FROM AUTHOR]

We present an optical field measurement technique for measuring scalar concentration field in wind tunnels using smoke particles, demonstrating its application through measurements of particle concentration and particulate dispersion in the turbulent wake of a simplified vehicle model (Ahmed body). Experiments involved the release of smoke particles (Ethylene-Glycol) from a source placed behind Ahmed body in the wind tunnel (at model length based Reynolds no., R e l = 1.9 × 10 5 ). The smoke particles were illuminated using a laser sheet and recorded using a digital camera. An optical technique similar to PLIF (Planar Laser-Induced Florescence) but adapted for the Mie-scattering of light by smoke particles is developed and implemented. A method for compensating the laser beam attenuation in the smoke medium is also discussed and implemented on the test flow. Calibration of the image intensities with absolute particle concentration has been done, and the Beer–Lambert law is shown to apply. Laser attenuation along the beam path is corrected using an extinction model based on the Beer–Lambert law. An iterative approach for the laser attenuation correction is applied. Using these, quantitative measurements of smoke concentrations are obtained. These experimental results are compared with earlier cold wire thermometry measurements. The results obtained by the current technique are in good agreement with the earlier results. It is observed that not accounting for the attenuation correction can lead to significant errors in the measured concentration field. The presented technique can be used to obtain instantaneous and time-averaged pollutant concentration fields that are resolved in space and time. [ABSTRACT FROM AUTHOR]

Aim: To develop an accommodating, wide‐angle, schematic eye for emmetropia and myopia in which spectacle refraction and accommodation level are input parameters. Method: The schematic eye is based on an earlier unaccommodated refraction‐dependent eye for myopia developed by Atchison in 2006. This has a parabolic gradient index lens and parameters derived from biometric and optical measurements on young adults. Several parameters are linearly dependent upon spectacle refraction (anterior radius of curvature of the cornea, axial length and vertex radii of curvature and conic asphericities of a biconic retina). The new accommodated schematic eye incorporates accommodation‐dependent changes in several lens‐related parameters. These changes are based on literature values for anterior chamber depth, lens thickness, vitreous chamber depth, lens surface radii of curvature and lens front surface asphericity. A parabolic variation of refractive index with relative distance from the lens centre is retained, with the same edge and centre refractive indices as the earlier model, but the distribution has been manipulated to maintain focus near the retina for the emmetropic case at 0 and 4 D accommodation. The asphericity of the lens back surface is changed so that spherical aberration and peripheral refraction approximately match typical literature trends. The model is used to compare spherical aberration and peripheral refraction in eyes with up to 4 D of myopia and 4 D of accommodation. Results: The levels of spherical aberration in the unaccommodated schematic eyes are similar to literature values for young adults, but the changes in spherical aberration with accommodation are approximately two‐thirds of that found in an experimental study. As intended, peripheral refractions in the accommodated schematic eyes are similar to those of their unaccommodated counterparts. Conclusion: The wide‐angle model extends the range of schematic eyes to include both refraction and accommodation as variable input parameters. It may be useful in predicting aspects of retinal image quality. [ABSTRACT FROM AUTHOR]

Background: Hemolysis in mechanical circulatory support systems is currently determined quantitatively. To also locally resolve hemolysis, we are developing a fluorescent hemolysis detection method. This requires a translucent two‐phase blood analog fluid combined with particle image velocimetry, an optical flow field measurement. The blood analog fluid is composed of red blood cell surrogates. However, producing surrogates in sufficient volume is a challenge. We therefore present a high‐volume and high‐concentration production for our surrogates: ghost cells, hemoglobin‐depleted erythrocytes. Methods: In the ghost cell production, the hemoglobin is removed by a repeated controlled osmolar lysis. We have varied the solution mixture, centrifugation time, and centrifugation force in order to increase production efficiency. The production is characterized by measurements of output volume, hematocrit, transparency, and rheology of the blood analog fluid. Results: The volume of produced ghost cells was significantly increased, and reproducibility was improved. An average production of 389 mL of ghost cells were achieved per day. Those ghost cells diluted in plasma have a rheology similar to blood while being permeable to light. Conclusion: The volume of ghost cells produced is sufficient for optical measurements as particle image velocimetry in mechanical circulatory support systems. This makes further work on experimental measurements for a locally resolved hemolysis detection possible. [ABSTRACT FROM AUTHOR]

The quantitative measurements of the soot volume fraction can deliver important validation data for detailed models of soot inception, growth, and oxidation in hydrocarbon-fueled flames – a process still not fully understood. Therefore, the sensitive and non-intrusive optical measurement of soot levels in fuel-rich steady flames is highly desirable. This work presents the first in situ Cavity Ring-Down Extinction (CRDE) setup for monitoring soot concentration levels in the low-ppb range in premixed ethylene/air stagnation flames stabilized on a flat flame burner at elevated pressure. The high-reflectivity CRD mirrors were mounted in nitrogen-flushed chambers attached to and separated from the flame area by small diameter apertures. CFD simulations supported the dimensioning of the purge flows and visualized possible perturbation of the cold- and hot-gas (from the flame) flows inside the burner housing. Within the uncertainties of the present experimental conditions and based on results from other labs for similar flame conditions, the pressure dependence of the evaluated soot volume fraction fV was fitted to a power-law ansatz with an exponent n between 2.1 and 2.6 depending on the equivalence ratio. A global thermal rate constant for surface growth, k SG ≈ 49 ± 20 s - 1 , was found for a measured flame temperature of 1750 ± 100 K in an atmospheric pressure flame, in gross agreement with results in the literature, which demonstrates the potential of the current setup for soot diagnostics in laminar premixed elevated pressure flames. A detection limit for fV of above 40 ppt has been determined from a comparative measurement of CO2 having a small absorption coefficient at the laser wavelength of 1064 nm. [ABSTRACT FROM AUTHOR]

This study aimed to fabricate an ultraviolet (UV) photodetector by using nanocomposite films of tin oxide (SnO2) and zinc oxide (ZnO) prepared through the hydrothermal method. X-ray diffraction analysis revealed that the films exhibited polycrystalline structures, with crystallite sizes of 11.55 nm for ZnO and 6.87 nm for SnO₂. Crystallite size decreased because of the incorporation of ZnO into the SnO₂ lattice. Field-emission scanning electron microscopy images demonstrated that the nanoparticles possessed a spherical shape, and their morphology did not change after mixing ZnO and SnO₂. Energy-dispersive X-ray spectroscopy confirmed the purity of the nanocomposite films and the lack of foreign particles or impurities. Optical measurements indicated improved optical transmittance and increased energy band gap with high ZnO ratios, reflecting the influence of nanocomposite formation on the films' optical properties. Hall effect measurements showed that all the films exhibited n-type conductivity. I–V measurements revealed Schottky's behavior in the mixed films, with a considerable and rapid increase in photocurrent upon UV light exposure. The films demonstrated exceptional sensitivity of 1082% and a quantum efficiency of 71.01% at a 10% ZnO mixing ratio, as well as fast rise and fall times of less than one second. These findings highlight the potential of SnO₂-ZnO nanocomposites for advanced applications in UV detection, environmental monitoring, and optoelectronic device development. [ABSTRACT FROM AUTHOR]

This research utilizes a precursor solution of SnCl2 and SC(NH2)2 at varying sulfur concentrations of 0.5, 0.6 and 0.7 M to fabricate SnxSy films through the nebulizer spray technique to establish the role of sulfur concentration on its phase formation. The crystallographic structure, morphology, optical and electrical properties of the deposited films were analyzed using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, UV-Vis spectroscopy and four probe measurements. X-ray diffraction analysis revealed the crystalline phases present in the films, with distinct peaks corresponding to various phases of SnxSy, indicating the successful incorporation of sulfur at different concentrations. Scanning electron microscopy provided insights into the surface morphology, demonstrating uniform film deposition and varying grain sizes and shapes influenced by sulfur concentration. Energy dispersive X-ray spectroscopy confirmed the elemental composition of the films, with the ratio of tin to sulfur aligning with the initial concentrations in the precursor solution. Optical measurements through UV-Vis spectroscopy indicated enhanced light absorption properties with increasing sulfur content, the value of band gap reaching a minimum of 1.31 eV for higher molar concentration of sulfur which is found to be beneficial for photovoltaic applications. Finally, four probe measurements determined a maximum electrical conductivity of 2.18 × 10− 8 Ω-1cm-1 and a highest charge carrier mobility of 6.54 × 1015 cm-1 for 0.7 M revealing the influence of sulfur concentration variation on the electrical properties of the prepared films. The findings suggest that tuning sulfur concentration can optimize the properties of SnxSy films to enhance its performance in photovoltaic applications. [ABSTRACT FROM AUTHOR]

Herein, CdTe/MnS core/shell nanoparticles dispersed in an aqueous solution have been synthesized. The formation of MnS semiconductor shell occurs by spontaneous self‐assembly. This process is activated by thermal hydrolysis that removes the excess of thiol and releases S2− ions. In this process, Mn2+ ions on the surface of the CdTe nanoparticles bind to S2− ions to produce a fine semiconducting layer of MnS. Measurements of Raman spectroscopy, optical absorption, and electrochemical measurements are performed. The Raman spectrum shows CdTe characteristic bands at 141 and 163 cm−1. Bands at 221 and 444 cm−1 are associated with the MnS structure. Cyclic voltammetry and differential pulse voltammetry are used to estimate the electrochemical gap at ≈2.47 eV. Absorption optical measurements show tree absorption bands. A broad band between 460 and 520 nm is associated with the first transition in CdTe nanoparticle. The absorption spectrum reveals an optical gap in the range of 2.41–2.33 eV for all the refluxed samples. These values are consistent with those obtained with the electrochemical measurements. The results evidence the formation of a core–shell semiconducting nanostructure made of CdTe nanoparticles coated with a spontaneously self‐assembled thin layer of MnS nanoparticles. [ABSTRACT FROM AUTHOR]

Panchromatic dyes have been highly useful in the realm of optical devices. Here, we report that panchromatic dyes with heterohelicenes have been successfully synthesized using a donor‐acceptor strategy. Our synthesis resulted in the creation of π‐extended aza[5]helicene oligomers with butadiyne linkages, which displayed bathochromically shifted absorption and emission spectra. The solvent‐dependent optical measurements revealed the intramolecular charge transfer characteristic of these molecules, and theoretical calculations described the biased molecular orbitals on the azahelicene units that generated the charge‐transfer characteristic. Encouraged by these results, we also prepared donor‐acceptor‐donor dyads using azahelicenes and dimide derivatives, resulting in panchromatic absorbing characteristics covering the range from 250 nm to 800 nm. Theoretical calculations showed the presence of mixed charge‐transfer transitions and localized transitions on the azahelicene units, which led to a broad light‐absorbing property covering the near IR region. Additionally, we conducted measurements of circular dichroism and circularly polarized luminescence for the obtained products. The g‐values were reduced by oligomerization, indicating that the lowest energy transitions were allowed in nature. [ABSTRACT FROM AUTHOR]

Field-resolved measurements of few-cycle laser waveforms allow access to ultrafast electron dynamics in light–matter interactions and are key to future lightwave electronics. Recently, sub-cycle gating based on nonlinear excitation in active pixel sensors has allowed the first single-shot measurements of mid-infrared optical fields. Extending the techniques to shorter wavelengths, however, is not feasible using silicon-based detectors with bandgaps in the near-infrared. Here, we demonstrate an all-optical sampling technique for near-infrared laser fields, wherein an intense fundamental field generates a sub-cycle gate through nonlinear excitation of a wide-bandgap crystal, in this case, ZnO, which can sample the electric field of a weak perturbing pulse. By using a crossed-beam geometry, the temporal evolution of the perturbing field is mapped onto a transverse spatial axis of the nonlinear medium, and the waveform is captured in a single measurement of the spatially resolved fluorescence emission from the crystal. The technique is demonstrated through field-resolved measurements of the field reshaping during nonlinear propagation in the ZnO detection crystal. [ABSTRACT FROM AUTHOR]

Significance: We present a system to measure and analyze the complete polarization state distribution of speckle patterns generated from in vivo tissue. Accurate measurement of polarization speckle requires both precise spatial registration and rapid polarization state acquisition. A unique measurement system must be designed to achieve accurate images of polarization speckle patterns for detailed investigation of the scattering properties of biological tissues in vivo. Aim and approach: This system features a polarization state analyzer with no moving parts. Two pixel-polarizer cameras allow for the instantaneous acquisition of the spatial Stokes vector distribution of polarization speckle patterns. System design and calibration methods are presented, and representative images from measurements on liquid phantoms (microsphere suspensions) and in vivo healthy and tumor murine models are demonstrated and discussed. Results and Conclusions: Quantitative measurements of polarization speckle from microsphere suspensions with controlled scattering coefficients demonstrate differences in speckle contrast, speckle size, and the degree of polarization. Measurements on in vivo murine skin and xenograft tumor tissue demonstrate the ability of the system to acquire snapshot polarization speckle images in living systems. The developed system can thus rapidly and accurately acquire polarization speckle images from different media in dynamic conditions such as in vivo tissue. This capability opens the potential for future detailed investigation of polarization speckle for in vivo biomedical applications. [ABSTRACT FROM AUTHOR]

With the rapid development of the electronic information industry, more and more attention has been paid to piezoelectric ceramic materials, but the electrical properties and characteristics of piezoelectric ceramic materials have problems such as high cost and inconvenient measurement. In this paper, a new method of electroinduced strain measurement of piezoelectric ceramics is proposed, and an innovative measuring device is constructed based on the working mode and testing principle of an optical displacement sensor and piezoelectric ceramics. An optical displacement measuring device with a simple structure, convenient operation, high measurement accuracy, and good cost benefit was designed and manufactured, and the electroinduced strain performance of piezoelectric ceramics was effectively measured. It is verified by experimental analysis that the device can accurately measure the axial displacement of various piezoelectric ceramics, the measurement accuracy is comparable to the existing equipment, the error is less than 10%, and has good stability and repeatability, which provides a reliable technical means for the performance measurement of piezoelectric ceramics. [ABSTRACT FROM AUTHOR]

Optical interferometry has emerged as a cornerstone technology for high-precision length measurement, offering unparalleled accuracy in various scientific and industrial applications. This review provides a comprehensive overview of the latest advancements in optical interferometry, with a focus on grating and laser interferometries. For grating interferometry, systems configurations ranging from single-degree- to multi-degree-of-freedom are introduced. For laser interferometry, different measurement methods are presented and compared according to their respective characteristics, including homodyne, heterodyne, white light interferometry, etc. With the rise of the optical frequency comb, its unique spectral properties have greatly expanded the length measurement capabilities of laser interferometry, achieving an unprecedented leap in both measurement range and accuracy. With regard to discussion on enhancement of measurement precision, special attention is given to periodic nonlinear errors and phase demodulation methods. This review offers insights into current challenges and potential future directions for improving interferometric measurement systems, and also emphasizes the role of innovative technologies in advancing precision metrology technology. [ABSTRACT FROM AUTHOR]

Van der Waals materials and devices incorporating them exhibit highly thickness‐dependent properties. The small lateral dimensions of mechanically exfoliated 2D‐layered flakes, however, remarkably complicate their precise thickness determination. Quantitative analysis of reflectance measurements using optical microspectroscopy is proven to be as precise as spectroscopic ellipsometry while providing an easily adaptable and non‐destructive method for thickness determination. The use of magnifying objective lenses allows obtaining the reflectance within a measurement spot of only a few microns in diameter. When the dimensions of exfoliated flakes are even smaller, however, the acquired reflectance is a superposition of those of the material of interest and the subjacent materials. To overcome this limitation, a facile approach to reduce the resolvable structure size by combining the evaluation of the reflectance measurement via transfer matrix method with spatial information extracted from optical micrographs is introduced. The efficacy when characterizing micrometer‐sized flakes is exemplarily demonstrated for thickness determination of highly oriented pyrolytic graphite and a thin film of silicon dioxide. It is shown that a maximum error of less than 10% is achieved even when the flake only covers 20% of the measurement spot. [ABSTRACT FROM AUTHOR]

We present the first controlled-environment measurements of the optical path-length change response of telecommunication submarine cables to active seismic and acoustic waves. We perform the comparison among integrated (optical interferometry) and distributed (distributed acoustic sensing, DAS) fibre measurements and ground truth data acquired by 58 geophones, 20 three-axis seismometers and 7 microphones. The comparison between different seismic acquisition methods is an essential step towards full validation and calibration of the data acquired using novel cable-based sensing techniques. Our experimental data demonstrates broadside sensitivity of integrated optical phase measurements, in contrast to predictions from the prevailing model for this type of sensing. We also present evidence of a fast-wave arrival, which we attribute to coupled energy propagating through the metal armour of the submarine cables at a considerably faster velocity than the subsurface and acoustic waves measured during our tests. The latter process can greatly affect the detected optical signal. The experimental setup allowed us to also observe how sensing measurements on separate optical fibres within the same cable can lead to significantly different detected waveforms. Constraining the effects of the fibre architecture on recorded signals can identify factors that contribute to the non-linear response of such a sensing system. [ABSTRACT FROM AUTHOR]

The similarities in the liquid–liquid phase separation (LLPS) phenomenon between membrane-less organelles (MLOs) and coacervates make them an ideal platform for studying the nature of life. Herein, we have developed a peptide–protein coacervative system between the positively charged poly- L -lysine peptide and negatively charged intrinsically disordered Pup protein to model the electrostatic nature of MLOs, providing insights into their in vivo mechanisms and potential therapeutic targets. We have constructed a phase diagram for coacervate formation at different concentrations of the Pup-PLL system, determined by turbidity measurements and optical microscopy. Fluorescence microscopy confirms the presence of both the polymers in the coacervates and the pH dependent studies confirm the role of electrostatics and emphasize the significance of charge density during coacervation. [ABSTRACT FROM AUTHOR]

This work reports on a comparative analysis of electrical and optical measurements for structural characterization and for assessing signal transduction performance of a redox-labeled DNA-based sensing platform. We conducted complementary investigations employing conventional electrochemical techniques with electric current measurements in cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) and confronted those results with optical measurements using surface plasmon waves while the redox assembly was undergoing similar electrochemical modulation as in the electrical CV and EIS measurements. The specific sensor configuration deployed here was composed of a methylene blue (MB)-modified single-stranded DNA (ssDNA) signaling probe and an unlabeled capture ssDNA probe that complements the signaling probe. Two types of signaling probes were employed: one with MB attached to the 3′ end, which positions the redox marker closer to the electrode surface upon hybridization with the capture probe, and the other with MB attached to the 5′ end, which places the redox marker farther from the electrode surface. For each molecular assembly and for each electrochemical modulation protocol, both the electrical and optical experimental data were quantitatively analyzed to determine the surface density of electro-active species and the rate of electron transfer between the redox marker and the electrode surface. Our experimental results highlight the consistency of the confronted methodologies and indicate that optical impedance spectroscopy utilizing electrochemically modulated surface plasmon waves, which is a transduction protocol immune from non-faradaic interferents that invariably are present in the electrical methodology, can provide a powerful route for developing a redox-labeled DNA-hybridization biosensing strategy. [ABSTRACT FROM AUTHOR]

Spectroscopic techniques coupled with chemometric approaches have been widely used for quality evaluation of agricultural and food (agri-food) products due to the nondestructive, simple, fast, and easy characters. However, these techniques face the issues or challenges of relatively weak robustness, generalizability, and applicability in modeling and prediction because they measure the aggregate amount of light interaction with tissues, resulting in the combined effect of absorption and scattering of photons. Optical property measurement could separate absorption from scattering, providing new insights into more reliable prediction performance in quality evaluation, which is attracting increasing attention. In this review, a brief overview of the currently popular measurement techniques, in terms of light transfer principles and data analysis algorithms, is first presented. Then, the emphases are put on the recent advances of these techniques for measuring optical properties of agri-food products since 2000. Corresponding applications on qualitative and quantitative analyses of quality evaluation, as well as light transfer simulations within tissues, were reviewed. Furthermore, the leading groups working on optical property measurement worldwide are highlighted, which is the first summary to the best of our knowledge. Finally, challenges for optical property measurement are discussed, and some viewpoints on future research directions are also given. Highlights: Emerging techniques for measuring optical properties are briefly introduced Qualitative analyses of maturity evaluation and defect detection are reviewed Quantitative analyses of attribute prediction and microstructure estimation are presented Light transfer simulations based on optical properties are comprehensively discussed Leading groups are summarized for the first time, to the best of our knowledge Challenges and prospects for optical property measurement are given [ABSTRACT FROM AUTHOR]

Optical thermometry has attracted significant interest due to its advantages of non-invasive nature, contact-free operation, and high spatial resolution. In this study, we developed and synthesized a novel series of Sr 3 TaGa 3 Si 2 O 14 :Tb3+,Eu3+ phosphors. Notably, the emission peak of Eu3+ ions was significantly enhanced by increasing the Tb3+ ion concentration under 368 nm excitation, facilitated by energy transfer between the ions. The distinct thermal quenching behaviors of Tb3+ and Eu3+ enabled an assessment of the temperature sensing capabilities of these phosphors, utilizing the fluorescence intensity ratio (FIR) of I 541nm / I 616nm , and achieving a maximum sensitivity of 0.76% K−1 at 498 K. Furthermore, by varying the Eu3+ ion concentration, these phosphors can achieve tunable multicolor emissions, making them ideal for anti-counterfeiting applications. These findings suggest that STGSO:Tb3+,Eu3+ phosphors are promising candidates for optical temperature measurement and customizable multicolor anti-counterfeiting technologies. [ABSTRACT FROM AUTHOR]

In this paper, we report on the measurement of the optical properties (absorption and scattering coefficients) of photoluminescent turbid media using a homemade integrating sphere setup equipped with a tunable monochromatic light source. The hemispherical reflectance and transmission data are analyzed with the radiative transfer equation using a Monte Carlo simulation-based lookup table to obtain the optical properties of the sample. The results are compared with the optical properties received from a classical integrating sphere setup equipped with a broadband white light source. The additional light of the photoluminescence generates artifacts within the optical properties, which are not present using a monochromatic light source. Additionally, a batch of samples with a broad range of scattering coefficients and dye concentrations were prepared and characterized with the aforementioned setup. The findings can help to generate a digital twin with the optical properties of the sample, which improves the physically based rendering and the design of, e.g., white-light LEDs. Dental restoration and photodynamic therapy also benefit from determination of the optical properties of photoluminescent turbid media. [ABSTRACT FROM AUTHOR]

We demonstrate the advantage of using two-color Kerr rotation spectroscopy to study the long-lived valley polarization in a suspended WSe2 monolayer. Low-temperature optical measurements under electrostatic gating reveal the high degree of freedom in tailoring the properties of the suspended monolayer by controlling optical interference at the monolayer, strain, and the carrier density of the material. We examine the lifetime of spin-valley polarized carriers by using the reflected light in a two-color pump-probe experiment. The observed dependence of the Kerr rotation lifetimes on the gate voltage and probe laser energy allows us to examine their origins associated with different forms of excitons. Our results show possibilities for analyzing long-lived valley polarization dynamics in gate-tunable suspended monolayers by using Kerr rotation, where we can exclude the influence of substrate perturbations on the carrier dynamics. [ABSTRACT FROM AUTHOR]

Optical density measurement has been used for decades to determine the microorganism concentration and more rarely for mammalian cells. Although this measurement can be carried out at any wavelength, studies report a limited number of measurement wavelengths, mainly around 600 nm, and no consensus seems to be emerging to propose an objective method for determining the optimum measurement wavelength for each microorganism. In this article, we propose a method for analyzing the absorbance spectra of ESKAPEE bacteria and determining the optimum measurement wavelength for each of them. The method is based on the analysis of the signal-to-noise ratio of the relationships between concentrations and optical densities when the measurement wavelength varies over the entire spectral range of the absorbance spectra measured for each bacterium. These optimum wavelengths range from 612 nm for Enterococcus faecium to 705 nm for Acinetobacter baumannii. The method can be directly applied to any bacteria, any culture method, and also to any biochemical substance with an absorbance spectrum without any particular feature such as an identified maximum. [ABSTRACT FROM AUTHOR]

Vanadium-doped zinc oxide (V-doped ZnO) nanostructures synthesized using a solution combustion method are exploited as efficacious photoanode materials for N719 dye-sensitized solar cells. The effect of fuels, including polyethylene glycol (PEG-400) and urea, on the morphological and structural properties of vanadium-doped ZnO nanostructures is elucidated in detail. Using PEG-400 as fuel, the doping of vanadium on ZnO nanostructures effectively transformed the nanoparticles into nanorods, whilst the conversion of nanorods into nanoparticles was conducted with the aid of urea fuel. Optical measurements and X-ray diffraction showed no major shift in the wavelength and peak position, respectively, indicating that vanadium is present on the surface of ZnO rather than in the interstitial position. The high surface area of the material revealed that mesopores present in the photoanode materials, which was 129 m2 g−1 for the sample synthesized using PEG-400 as fuel, offered higher power conversion efficiency (PCE) due to higher pore volume (0.317 cm3 g−1) and dye adsorbing capability as revealed through BET analysis. The PCE of the PEG-400 fuel used sample showed 5.4% efficiency, whereas the urea fuel sample exhibited 4.9% efficiency. IPCE measurements displayed a wavelength maximum at 510 nm with 22.14% of the IPCE value, indicating that the PEG-400 fuel sample (ZnO–V5%) shows the highest efficiency among other DSSC devices. [ABSTRACT FROM AUTHOR]

Interband cascade lasers (ICLs) are becoming increasingly valuable in mid-infrared applications due to their low power consumption and compatibility with silicon photonic integration, particularly for trace gas sensing. ICLs have demonstrated room-temperature continuous-wave operation in the 3–6 μm range, with excellent performance around 3.3 μm. A key factor limiting ICL performance at longer wavelengths is optical loss, i.e., caused by the intervalence band transitions. These losses increase with hole concentration in the active region, leading to a pronounced current-dependence of the optical losses in ICLs. Conventional methods that infer optical losses from length-dependent variations in parameters such as slope efficiency or threshold current require the assumption of constant optical loss. In this study, we present a direct optical transmission measurement technique to determine waveguide losses. Our experiments confirm strongly increasing waveguide losses with current density, directly impacting the quantum efficiency of ICLs. This approach offers a precise evaluation of optical losses and bears a functional alternative compared to traditional methods, addressing the limitations of assuming constant losses and providing enhanced insight into ICL performance across various wavelengths. [ABSTRACT FROM AUTHOR]

Spectroscopic ellipsometry (SE), which measures the thickness of thin films in a non-contact way with an accuracy of angstroms, has been widely used for optical metrology. Several types of SE are available both commercially and in research, although they require specific implementations depending on the application. Here, we theoretically and experimentally demonstrate the Frequency Division Multiplexing Spectroscopic Ellipsometry (FDM-SE) technique. With respect to conventional rotating polarizing element ellipsometry, our variant uses discrete-wavelength intensity-modulated laser diodes. This modification enables the measurement of optical properties of materials at multiple wavelengths simultaneously. We further compare the performance of the FDM-SE to a commercial instrument by measuring the thickness of SiO2 films on a Si wafer, obtaining a difference between the measured thicknesses with both methods of less than 5 Å. The proposed FDM-SE technique therefore provides a more efficient alternative to conventional SE with a high accuracy for thickness measurements. Spectroscopic ellipsometry, capable of measuring the thickness of thin films with an accuracy of angstroms, has been widely used both in research and commercially. Here, the authors theoretically and experimentally demonstrate a unique variant of spectroscopic ellipsometry utilizing frequency division multiplexed lasers of different wavelengths. [ABSTRACT FROM AUTHOR]

We present a study of the radio and optical properties of the high-frequency peaker (HFP) blazar PKS 1614 051 at based on the data covering the time period of 1997–2024. The radio data are represented by the instantaneous 1–22 GHz measurements from the SAO RAS RATAN-600 radio telescope, the 5 and 8 GHz data from the IAA RAS RT-32 telescopes, and the 37 GHz data from the RT-22 telescope of CrAO RAS. The optical measurements in the band were collected with the SAO RAS 1-m Zeiss-1000 and 0.5-m AS-500/2 telescopes, and the ZTF archive data. We have found low overall variability indices (0.1–0.2) and a median spectral peak at 4.6 GHz, which is stable during the long-term period of monitoring. An analysis of the radio light curves reveals significant time delays (0.6 to 6.4 yrs) between the radio frequencies along with variability timescales ranging from 0.2 to 1.8 yrs in the source's rest frame, which is similar to the blazars at lower redshifts. Spectral modeling suggests the presence of both synchrotron self-absorption (SSA) and free-free absorption (FFA) processes. Based on the SSA model, we provide estimates of the magnetic field strength which peaks at approximately 100 mG. A spectroscopic study with the BTA SCORPIO-1 spectrograph has found evidence of the regular motion of a neutral hydrogen envelope around the blazar center, which confirms the presence of a sufficient amount of gaseous matter to form an external FFA screen. The results highlight the importance of multi-wavelength and long-term monitoring to understand the physical mechanisms driving the variability in high-redshift blazars. [ABSTRACT FROM AUTHOR]

Interfering radiation, such as self-emitting thermal radiation, infrared radiation from heating sources, and combustion gas radiation, significantly impacts the use of optical thermometry. How to improve the precision of temperature measurement in such an environment is a key issue. Therefore, this work aimed to quantitatively analyze the temperature measurement precision of luminescence lifetime thermometry for measuring the temperatures of hot components in environments with interfering radiation. In this paper, based on the quantitative analysis of measurement noise of optical signal and the error propagation theory, we proposed a theoretical model for predicting the temperature measurement precision of luminescence lifetime thermometry. Using blue LED as the interfering radiation source, the temperature measurement experiments of high-temperature surfaces under different interfering radiation intensities were carried out. By comparing the measured precision based on the standard deviation of repeated experiments with the predicted precision of the theoretical model proposed in this paper, the reliability of this theoretical model was verified. The experiments also revealed that the temperature measurement precision was linearly related to the square root of the measured signal intensity (i.e., the sum of luminescence signal and interfering radiation signal). With the increase of the background interfering radiation intensity, although the accuracy of temperature measurement did not change significantly, the measurement noise increases, resulting in a significant increase in random error of measured temperature. This work provides guidance for developing luminescence lifetime thermometers and their applications in environments with interfering radiation. [ABSTRACT FROM AUTHOR]

Lasers with narrow linewidths and long-term frequency stability are required in various applications such as precision measurement and optical frequency reference. Here, we propose a hybrid method that combines techniques of optical feedback and optical heterodyne modulation locking to an external Fabry-Perot cavity to reduce the linewidth and frequency drift of the laser. The method is demonstrated on a distributed feedback laser with a free-running linewidth of 2 MHz. The frequency noise power density spectrum shows a reduction of 50 dB in the low-frequency range and 30 dB for white noise, and the linewidth has been reduced to 20 kHz. The lock can be maintained for days. This method can be applied to various lasers of different wavelengths. [ABSTRACT FROM AUTHOR]

Significance: For therapeutic approaches for upper tract urothelial carcinomas, the absorption μa and reduced scattering μ's coefficients of these tissues are essential parameters to quantitatively evaluate the distribution of light treatment effects. Aim: The μa and μ' s spectra of the human ureter, fatty tissue, ureteral and renal pelvic carcinomas, and porcine ureter and fatty tissue are measured over 400 to 700 nm to evaluate projected light penetration depths δ. Approach: The optical properties were determined with a double integrating sphere optical system and inverse Monte Carlo methods. δ was calculated and compared between normal and cancerous human tissues as well as between normal human and porcine tissues. Results: μa and μ's spectra of each tissue were determined. The δ of the normal human ureter was less than those of the ureteral and renal pelvic carcinomas, whereas that of the porcine ureter was similar to that of the human ureter over 400 to 600 nm and ~0.2 times smaller above 600 nm. Conclusion: Optical properties of human and porcine upper urinary tracts provide insights into light distributions and the validity of ex vivo porcine models in preclinical evaluations of laser treatments. [ABSTRACT FROM AUTHOR]

Lead-free K 0.5 Na 0.5 NbO 3 (KNN) ferroelectric film and transparent La 0.06 Ba 0.94 SnO 3 (LBSO) bottom electrode are fabricated on (001)-oriented SrTiO 3 (STO) substrate by sol-gel. The characterization results confirm an epitaxial relationship between the films and the substrate, as well as a uniform structure and good crystallization quality of the films. The optical measurement shows that the film heterostructure exhibit a high transmittance with a maximum transmittance of ∼80 %. The polarization-electric field (P-E) curves demonstrate that the twice remanent polarization value of the ∼500 nm thick KNN film reaches up to 28 μC/cm2 under an electric field of 800 kV/cm, and the effective piezoelectric strain constant (d 33 ∗) is measured as 24.8 p.m./V. The dielectric properties of the film are displayed, and the leakage behavior can be divided into three stages of Ohmic conduction, Schottky emission and Poole-Frenkel emission with increasing the applied electric field. This study indicates that transparent lead-free ferroelectric KNN heterostructures can be prepared using a cost-effective sol-gel method and shows promise for future applications. [ABSTRACT FROM AUTHOR]