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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]

Spectroscopic ellipsometry and some other optical metrology techniques, such as reflectometry and scatterometry, are model-based optical measurements and, therefore, require appropriate modeling to determine the geometric and material properties of substrates, thin films, and multilayer structures. Parametric sensitivity analysis (SA) provides essential assistance in the model-building process to quantify the relative importance of model parameters for model output and to identify those with high/little influence. SA can be performed in a variety of ways, and this article discusses an application of the Morris or elementary effect (EE) method, a screening type SA procedure, to spectroscopic ellipsometry modeling. The method is a global SA technique and uses a stepping of m parameters along certain so-called "trajectories" or sequences of points in parameter space, randomly constructed in order to maximally fill the volume of the m -dimensional parameter space. However, it was thought that the EE method relies greatly on a sampling strategy or a way of selecting "optimized trajectories" in the parameter space, i.e., a necessary number of trajectories chosen to be well spread over the space to properly cover the entire realistic ranges of all input factors. Here, we use two sampling methods for selecting trajectories with possibly different distributions and investigate their effects on the estimation of various sensitivity measures in spectroscopic ellipsometry data modeling. The SA results indicate that the performance of the sampling strategy should not be judged only by maximizing the trajectory spread but also include some additional convergence criteria for the sensitivity measures. [ABSTRACT FROM AUTHOR]

Radio frequencies in high-frequency (HF) and very high-frequency (VHF) bands (3–300 MHz) are challenging for Rydberg atom-based detection schemes, as resonant detection requires exciting atoms to extremely high energy states. We demonstrate a method for detecting and measuring radio frequency carriers in these bands via a controlled Autler–Townes line splitting. Using a resonant 18 GHz field, the absorption signal from Townes–Merritt sidebands created by a relatively low-frequency, non-resonant field can be enhanced. Notably, this technique uses a measurement of optical frequency separation of an avoided crossing to determine the amplitude of a non-resonant field. This technique also provides frequency-selective measurements of electric fields in the hundreds of MHz range with resolution of order 10 MHz. To show this, we demonstrate amplitude-modulated signal transduction on a MHz-range carrier. We further demonstrate reception of multiple tones simultaneously, creating a Rydberg "spectrum analyzer." [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]

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]

A series of double molybdates with palmierite-related structure phosphors K 5 Yb 1- x (MoO 4) 4 : x Er3+ were synthesized by a solid-state method. It has been demonstrated that the K 5 Yb 1- x (MoO 4) 4 : x Er3+ phosphors are capable of exhibiting the characteristic green and red UC emission of Er3+ ions with excitation at 980 nm. Moreover, the green light emission is far more than the red light emission, so that the sample emits a powerful green light, which belongs to the two-photon absorption process. The upconversion efficiency is peaked when the content of Er3+ ions is 10 mol %. The optical thermometry properties of phosphors were explored by observing that the green UC emission intensity is temperature dependent. The maximum sensor sensitivity of the studied phosphor was discovered to be about 1.61%K−1 at the optimum doping concentration. And the phosphor is demonstrated to have high thermal stability by temperature cycling test. Eventually, a green light-emitting diode device was realized by using synthesized particles and a 980 nm near-infrared chip, which can emit a more obvious green light when the voltage reaches 1.80 V and the current can reach 800 mA, thus confirming its applicability in solid-state lighting. And the LED devices have been tested for life stability with little or no light degradation. These properties make the phosphors not only suitable for non-contact optical temperature measurement, but also able to be applied to solid state lighting. [ABSTRACT FROM AUTHOR]

This work aims to electrodeposit Cr from a solution containing only Cr3+ ions but not any other complexing, buffering and pH agents, and study its corrosion behavior. The solution was investigated by cyclic voltammetry and ultraviolet–visible spectroscopy. It was obtained that it is rich in native Cr complexes including Cl. Cr was successfully coated from this solution by binary potential loop electrodeposition. First, − 0.7 V potential was applied for a time interval ranging from 5 to 30 s. Then, a − 1.8 V potential was applied to deposit the Cr layer with the thickness changed from 50 to 1000 nm. X-ray diffraction patterns showed that all films are in a bcc crystal structure. The Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and optical profilometry measurements inferred that the coatings include hydrated-Cl complexes mostly edges of the coating and cracks. The scanning electron microscopy images indicated that the cracks on the surface are tiny for the layers thinner than 500 nm but prominent for the layers thicker than 500 nm. The corrosion behavior was examined by electrochemical impedance spectroscopy and Tafel measurements. The coatings electrodeposited by the binary potential loop had a corrosion rate lower and resistance higher than those of the coatings electrodeposited at − 1.8 V potential. The corrosion parameters became superior for the coatings with layers thinner than 500 nm and the aged ones. [ABSTRACT FROM AUTHOR]

A series of glass ceramic samples precipitated with Ca2(Mg0.5Al0.5)(Si1.5Al0.5O7): Yb3+, Er3+ nanoparticles were synthesized by the melt quenching method to effectively recycle blast furnace slag. Their structures, morphologies, and luminescent properties were comprehensively investigated using X‐ray diffraction, transmission electron microscopy, and photoluminescence, respectively. The impact of adding Al2O3/SiO2 to the blast furnace slag raw material on the transmittance, hardness, and luminescent properties of the glass‐ceramics was analyzed. Upon excitation with a 980 nm laser, all glass‐ceramic samples emitted strong Er3+ upconversion luminescence at 526, 549, and 650 nm. Moreover, the addition of Yb3+ ions significantly enhanced the luminescent intensity. A dual‐mode temperature sensor based on fluorescence intensity ratios was realized using a single luminescent center. All results indicate that the glass ceramic samples prepared from blast furnace slag are potentially promising for self‐referential optical temperature measurement. [ABSTRACT FROM AUTHOR]

Polymethyl methacrylate (PMMA)/Congo Red (CR) and polyvinyl chloride (PVC)/CR composite films were prepared on optical glass by the drop method for optical measurements and also prepared as tablets under pressure for dielectrical measurements. The optical transmission spectra measurements for PMMA and PVC film doped with CR showed a highly absorption in the ultraviolet-visible (UV-Vis) optical range (at 353 nm and 518 nm) and considerably blocking in broad visible range (190 nm–640 nm). PMMA/CR and PVC/CR composite films containing congo red at a concentration of 1 wt% showed maximum absorption bands at 290 nm and 416 nm, but their transmittance percentages were reasonably reduced compared to those of pure PMMA and PVC. Both of composites indicated high transmittances between 640 nm and 800 nm. The optical constants of the PMMA/CR and PVC/CR composite films such as optical band energy gaps (Eg) estimated using Tauc's model, refractive index and reflectance (%) were calculated. UV–Vis, Fourier transform infrared spectroscopy (FTIR) and Thermogravimetry Analysis (TGA) measurements were used to confirm the breakdown of the -N = N- azo group bonds attached to the aromatic ring as a result of thermal decomposition of CR at 500 °C, and it was suggested that N2 gas was eliminated from the CR above 360 °C. The dielectric plots showed that the dielectric constant increased when the CR is doped up to 70 wt% in the polymer matrices. A further increase in the doping concentration of CR resulted in an increase of the dielectric constant. The dielectric constant decreased with an increase in the frequency for all of the samples. The ac (alternating current) conductivity values of PMMA and PVC showed an increase with increasing CR dopant in the polymer composites, while the ac conductivity values were found to be values between those of the pure polymers and CR. [ABSTRACT FROM AUTHOR]

Non-contact optical temperature measurement has attracted intense attention in recent years due to its advantages of high speed and high safety. In this work, a Lu2WO6:Er3+ phosphor was successfully prepared by a solid state reaction. The effective energy transfer from the [WO6]6− group to Er3+ was proved using the emission spectra and fluorescence lifetime measurements, with an estimated transfer efficiency of 51%. Benefiting from the self-luminescence of the [WO6]6− group, optical thermometry was established based on the fluorescence intensity ratio of [WO6]6− emission to Er3+ emission. Remarkably, strong emission color variability from blue to green was observed under 320 nm UV excitation as the temperature increases from 298 K to 548 K, while an opposite trend from green to cyan is observed under 378 nm UV excitation. The maximum relative sensitivity (SR Max) is 3.37% K−1 (298 K), which is highly superior to most of the previously reported values. [ABSTRACT FROM AUTHOR]

Image‐based measurements of underwater infrastructure dynamics is challenging due to the refractive nature of the environment. To mitigate this problem, a multimedia high‐speed videogrammetric technique is proposed. The approach monitors the motion states of the underwater object and introduces a virtual refracting interface compensation model. The spatial expression of the virtual refracting interface is first found as a convex surface. Through the proposed compensation model, the complex multimedia refraction imaging can be easily transformed to simple dual‐media refraction imaging. Combined with high‐speed videogrammetry, this multimedia imaging analysis approach can measure underwater deformation. Simulated and experimental testing confirmed the feasibility and reliability of the proposed approach with sub‐millimetre positioning accuracy. [ABSTRACT FROM AUTHOR]

The article discusses the development of high-performance and color-tunable copper(I)-based cluster scintillators for efficient X-ray imaging. A rapid flash synthesis method was introduced to create scintillators with desirable features such as wide-range luminescence tuning and resistance to X-ray irradiation. The resulting flexible films demonstrated a low detection limit and stable X-ray imaging capabilities, making them suitable for dynamic real-time imaging. The study highlights the potential of these innovative scintillators to enhance efficiency and accessibility in X-ray imaging applications. [Extracted from the article]

The aqueous solution cast method was used to create the biodegradable polymer nanocomposite (PNC) films from a blend of poly (vinyl alcohol) PVA and poly (vinyl pyrrolidone) PVP (70/30 wt %) and Fe2O3 nanoparticles (NPs). These PNC films were characterized using X-ray diffraction, scanning electron microscopy SEM, Fourier transform infrared spectroscopy FTIR, and ultraviolet-visible spectroscopy. XRD and FTIR results indicate that Fe+ 3 NPs interact with the host polymer. Optical, electrical, mechanical, and radiation shielding measurements were performed on the PNC films. From the optical measurements, the indirect optical band gap drops from 4.86 eV for the pure blend to 4.26 eV at the greatest NPs concentration. Optical limiting characterization shows that the output power of He-Ne and solid-state green laser beams is reduced from 22.98 to 3.6 mW and 6.59 to 1.4 mW, respectively, when the Fe2O3 NPs content in the blend matrix is increased to 6 wt %. The NGCal software was utilized to calculate nuclear radiation shielding properties. The findings demonstrated that when the concentration of Fe2O3 rose, the PNC films half-value layer and mean free path decreased. Mechanical measurements demonstrate that increasing the Fe2O3 content significantly improves nanocomposite films' yield and tensile strength. Tensile strength is measured at 27.03 MPa for the composite film containing 6 wt % Fe2O3, which is significantly higher than the 8.66 MPa of the pure (PVA-PVP) film. Compared to the other samples under examination, the 6 wt % Fe2O3 sample yielded the best results (based on the analyzed optical, electrical, mechanical, and radiation shielding properties). [ABSTRACT FROM AUTHOR]

The near-field interaction between quantum emitters, governed by Förster resonance energy transfer (FRET), plays a pivotal role in nanoscale energy transfer mechanisms. However, FRET measurements in the optical regime are challenging as they require nanoscale control of the position and orientation of the emitters. To overcome these challenges, microwave measurements were proposed for enhanced spatial resolution and precise orientation control. However, unlike in optical systems for which the dipole can be taken to be infinitesimal in size, the finite size of microwave antennas can affect energy transfer measurements, especially at short distances. This highlights the necessity to consider the finite antenna length to obtain accurate results. In this study, we advance the understanding of dipole–dipole energy transfer in the microwave regime by developing an analytical model that explicitly considers finite antennas. Unlike previous works, our model calculates the mutual impedance of finite-length thin-wire dipole antennas without assuming a uniform current distribution. We validate our analytical model through experiments investigating energy transfer between antennas placed adjacent to a perfect electric conductor mirror. This allows us to provide clear guidelines for designing microwave experiments, distinguishing conditions where finite-size effects can be neglected and where they must be taken into account. Our study not only contributes to the fundamental physics of energy transfer but also opens avenues for microwave antenna impedance-based measurements to complement optical FRET experiments and quantitatively explore dipole–dipole energy transfer in a wider range of conditions. [ABSTRACT FROM AUTHOR]

In recent years, people have higher requirements for temperature measurement with the development of optical temperature measurement. Meanwhile, the emission intensity of most fluorescent materials is quenched by thermal effects as the temperature rises, making it challenging to meet the specifications of fluorescent materials employed in the field of pyrometry. In this work, the pure phase of Yb3+/Er3+ ions co-doped Sc 2 W 3 O 12 phosphor was successfully prepared. Sc 2 W 3 O 12 : Yb3+, Er3+ samples showed strong green emission and weak red emission. The optimal doping concentrations of Yb3+ and Er3+ ions are 0.3 and 0.02, respectively. The potential upconversion luminescence (UCL) mechanism was investigated by analyzing the UCL spectra, downshift emission spectra and power dependence spectra of Yb3+/Er3+ ions co-doped Sc 2 W 3 O 12. The upconversion emission excitation path is mainly through Er3+ ions from 4I 11/2 absorption photon excitation to 4F 7/2 energy level, then the photons of 4F 7/2 relaxes to green and red emission energy levels and returns to ground state for emitting green and red light. In addition, according to the UCL green light intensity increasing with temperature, it serves as an optical temperature sensor. The temperature sensitivity of the sample was explored in the temperature range of 298 K–673 K. This study provides new materials and ideas for non-contact temperature sensing. [ABSTRACT FROM AUTHOR]

Hofmann coordination polymers (CPs) with cationic ligands provide an innovative strategy for recognizing π‐electron‐rich aromatic molecules – similar to the "little blue box". In this study, we demonstrate that hydroquinone molecules can be incorporated into these coordination polymers when redox‐active bipyridinium derivatives are used as axial ligands. The insertion leads to a significant structural modification, resulting in a shift of the spin transition by 150 K and an approximate 23 % increase in volume, caused by the strong donor‐acceptor π‐π stacking interaction formed between the ligands and the guest molecule. These findings have been confirmed through temperature‐dependent single crystal X‐ray diffraction, magnetic measurements and optical reflectivity measurements. [ABSTRACT FROM AUTHOR]

This paper presents new method for traceability assurance of measurements performed using hybrid measuring systems built using one system that is based on tactile point measurement method (for example: coordinate measuring machine, articulated arm coordinate measuring machine, laser tracker system) and the second one that is based on optical field measurement method (for example: structured light scanners, digital image correlation systems). Within works described in this paper a series of tests aimed at determining task-specific errors for measurements performed using such composed systems were run. Measurement tasks for which such errors were determined include length measurements and measurements of form deviations (roundness, flatness, etc). Measurements were performed using material standards representing various shapes, dimensions and geometric relations. Measurements were run in different orientations and positions of the standards. Types of standards along with orientations and positions used were chosen basing on the guidelines of the ISO 10360 standard, parts 2, 5, 7, 8, 9, 10, 12, VDI/VDE 2634 and longtime experience of authors of this paper. At the end, results of performed measurements were checked for consistency with results of material standards calibration and values of task- specific maximum permissible errors were established. Guidelines for using developed method in other hybrid systems were also presented in the paper. [ABSTRACT FROM AUTHOR]

Accurately measuring the form of structured composite surfaces in situ is critical for advanced manufacturing in various engineering fields. However, challenges persist in achieving precision, miniaturization, and calibration using current structured light techniques. In this work, a hybrid structured light with compact configuration is proposed for the in-situ and embedded form metrology of structured composite surfaces. The proposed technique contains three subsystems: phase-measuring deflectometry (PMD), fringe projection profilometry (FPP), and stereo vision. The PMD subsystem accurately reconstructs the form data of specular surfaces based on the principle of structured light reflection, and the FPP subsystem measures rough surfaces by projecting structured light onto them. Output data from these subsystems are then stitched to reconstruct a complete form of the measured composite surfaces. The compact configuration is explored to reduce the system volume to improve the technique's portability and embedded measurement ability. With the stereo vision subsystem as an intermediary, a novel calibration method is applied for calculating the relations among the subsystems to improve the hybrid structured light system's calibration and data stitching accuracy between PMD and FPP subsystems. Three calibration tools are designed and manufactured for the proposed calibration technique. A portable metrology prototype based on the proposed hybrid structured light technique's principle and configuration is also developed and then calibrated using the novel calibration method. An embedded measurement experiment in a diamond turning machine demonstrates that the proposed techniques can achieve 400 nm form accuracy in specular surface measurement. Highlights: A novel hybrid structured light-based technique is proposed for the in-situ and embedded form metrology of structured composite surfaces. A beam splitter (BS)-based compact configuration is used to improve the technique' portability and embedded measurement ability. A novel calibration method is applied to calculate the relations among the subsystems using the stereo vision subsystem as an intermediary. [ABSTRACT FROM AUTHOR]

Purpose: This work measures the performance characteristics of a hemispherical resonator gyroscope (HRG) and compares it with a numerical model. Design/methodology/approach: This work we explore the optical and piezoelectric measurement methods to determine the resonant frequency of HRG. These experimental results are compared with their numerically obtained values. To explore the performance characteristics, the effect of varying actuation voltages on the sense mode displacement and the piezoelectric sensor output was studied in the absence of input angular rate. The structure was then subjected to range of angular rate signals, at a constant actuation voltage and the corresponding sensor response was analysed. Findings: Experimental values of the resonant frequencies in drive and sense modes are found to be within 8% of the numerical results. The sensor output depicts a quadratic dependency on the applied angular rate, which is synchronous with the governing equations of the HRG. The experimental output is within 12% of that obtained numerically. The sensor is found to resolve upto 0.24 rad/s. Originality/value: This work presents an in-house developed inexpensive measurement setup for static and dynamic characterization of mesoscale MEMS gyroscopes. The measurement setup can also be modified accordingly for measurement of other MEMS-based devices. [ABSTRACT FROM AUTHOR]

Context. Numerous studies have reported significant displacements in the coordinates of active galactic nuclei (AGNs) between measurements using the very-long-baseline-interferometry (VLBI) technique and those obtained by the Gaia space observatory. There is consensus that these discrepancies do indeed manifest astrometrically resolved sub-components of AGNs rather than random measurement noise. Among other evidence, it has been reported that AGNs with VLBI-to-Gaia displacements (VGDs) pointing downstream of their parsec-scale radio jets exhibit higher optical polarization compared to sources with the opposite (upstream) VGD orientation. Aims. We aim to verify the previously reported connection between optical polarization and a VGD-jet angle using a larger dataset of polarimetric measurements and updated Gaia DR3 positions. We also seek further evidence supporting the disk-jet dichotomy as an explanation of such a connection by using millimeter-wave polarization and multiband optical polarization measurements. Methods. We performed optical polarimetric observations of 152 AGNs using three telescopes. These data are complemented by other publicly available polarimetric measurements of AGNs. We cross-matched public astrometric data from VLBI and Gaia experiments, obtained corresponding positional displacements, and combined this catalog with the polarimetric and jet direction data. Results. Active galactic nuclei with downstream VGDs are confirmed to have significantly higher optical fractional polarization than the upstream sample. At the same time, the millimeter-wavelength polarization of the two samples shows very similar distributions. Conclusions. Our results support the hypothesis that the VGDs pointing down the radio jet are likely caused by a component in the jet emitting highly polarized synchrotron radiation and dominating in the overall optical emission. The upstream-oriented VGDs are likely to be produced by the low-polarization emission of the central engine's subcomponents, which dominate in the optical. [ABSTRACT FROM AUTHOR]

Discovery of pulsations from a number of ultra-luminous X-ray (ULX) sources proved that accretion onto neutron stars can produce luminosities exceeding the Eddington limit by several orders of magnitude. The conditions necessary to achieve such high luminosities as well as the exact geometry of the accretion flow in the neutron star vicinity are, however, a matter of debate. The pulse phase-resolved polarization measurements that became possible with the launch of the Imaging X-ray Polarimetry Explorer (IXPE) can be used to determine the pulsar geometry and its orientation relative to the orbital plane. They provide an avenue to test different theoretical models of ULX pulsars. In this paper we present the results of three IXPE observations of the first Galactic ULX pulsar Swift J0243.6+6124 during its 2023 outburst. We find strong variations in the polarization characteristics with the pulsar phase. The average polarization degree increases from about 5% to 15% as the flux dropped by a factor of three in the course of the outburst. The polarization angle (PA) as a function of the pulsar phase shows two peaks in the first two observations, but changes to a characteristic sawtooth pattern in the remaining data set. This is not consistent with a simple rotating vector model. Assuming the existence of an additional constant polarized component, we were able to fit the three observations with a common rotating vector model and obtain constraints on the pulsar geometry. In particular, we find the pulsar angular momentum inclination with respect to the line of sight of ip = 15°–40°, the magnetic obliquity of θp = 60°–80°, and the pulsar spin position angle of χp ≈ −50°, which significantly differs from the constant component PA of about 10°. Combining these X-ray measurements with the optical PA, we find evidence for at least a 30° misalignment between the pulsar angular momentum and the binary orbital axis. [ABSTRACT FROM AUTHOR]

The Sc3+ ions doped NaYF4: Yb3+, Er3+ upconversion (UC) nanoparticles are synthesized by thermal decomposition method. We successfully obtained the upconversion luminescence (UCL) nanoparticles from green emission to red emission through doping Sc3+ ions with different concentrations. Based on the XRD, the phase change process of Sc3+ ions doped NaYF4 nanocrystalline phase were demonstrated. More importantly, through the analysis of UC spectrum data, the change in the phase of the NaY/ScF4: Yb3+, Er3+ nanocrystalline corresponds to the change in its luminous properties. It determines that the change of crystal field will lead to the change of luminescence, and then modulate the luminescence. NaScF4: Yb3+, Er3+ UC nanoparticles exhibit strong red light emission. In addition, the temperature-sensitive properties of the optimal doping concentration of Sc3+ ion were tested. The sensitivity of NaYF4: Yb3+, Er3+ nanoparticles doped with Sc3+ ion reached the maximum value of 0.024 K− 1 at 498 K. The nanocrystalline has great application value in the fields of optical temperature measurement, biomedicine, bioprobes and colorful display. [ABSTRACT FROM AUTHOR]

In this study, Fe2O3 was introduced into sodium zinc-based phosphate glass, replacing Na2O. Using the conventional melt quenching technique, a glass system with the chemical composition 45P2O5 − 34ZnO − (21-x) Na2O - xFe2O3 (where, x = 1, 2, 3, 4, and 5 mol%) was prepared. X-ray diffraction (XRD) analysis showed that this substitution did not alter the glass's amorphous structure. However, the density increased slightly, potentially due to the higher molecular mass of Fe2O3 compared to Na2O. This density change suggests a possible alteration in the glass's optical properties. Optical measurements revealed a shift towards the red spectrum and a decrease in transmittance, particularly at 543 nm, indicating increased optical loss. This loss was attributed to increased reflectance, not absorption. The optical band gaps decreased with higher Fe2O3 content, enhancing the glass's optical resistance, and making it suitable for applications like optical filters and shielding materials. The optical loss tangent analysis showed that the material's efficiency in transmitting electromagnetic energy decreased with Fe2O3 substitution, likely due to changes in the electronic structure. The study also noted that Fe2O3 improved optical absorption, as demonstrated by the Hydrogenic Excitonic Model (HEM). [ABSTRACT FROM AUTHOR]

Green hydrogen produced by electrolysis offers a high potential for reducing CO2 emissions and thus represents a promising approach for the decarbonization of aviation. However, propulsion systems based on direct hydrogen combustion require modified fuel injectors and combustion chambers to account for the particular combustion characteristics of hydrogen. Engineering those modifications requires the acquisition of experimental and numerical tools especially suited for this task and in the end validating them in a suitable environment. In this context, hydrogen combustion and its numerical simulation are presented with a dual-swirl burner in an optically accessible atmospheric combustor as an intermediate step. To ensure safe operation and to reduce the risk of flashback, fuel and air are injected nonpremixed. Good flame stability and mixing, which leads to potentially low NOx values, is achieved by introducing a swirling motion into the flows. In this study, the combustor is operated under atmospheric pressure at a globally lean equivalence ratio. Measurements of OH* radical chemiluminescence as well as infrared (IR) radiation as marker of the hot water vapor distribution have been carried out to identify the flame location and shape. The configuration is further analyzed by means of reacting large-eddy-simulations (LES). The comparison of the simulation results with the experimental reference data shows that the flame lift of height and global flame spread are correctly predicted by the simulation for both operating conditions. However, the combustion model does not precisely capture the flame stabilization mechanism, leading to a radial offset of the flame front. [ABSTRACT FROM AUTHOR]

A Fresnel mirror is introduced at a hollow-core photonic bandgap fiber end by fusion splicing a short single-mode fiber segment, to reflect the light backward to an optical frequency domain reflectometry. The backward Fresnel reflection is used as a probe light to achieve light speed measurement with a high resolution and a high signal-to-noise ratio. Thus, its group velocity is obtained with the round-trip time delay as well as the beat frequency at the reflection peak. Multiple Fresnel peaks are observed from 2180.00 Hz to 13,988.75 Hz, corresponding to fusion-spliced hollow-core fiber segments with different lengths from 0.2595 m to 1.6678 m, respectively. The speed of light in the air guidance is calculated at 2.9753 × 108 m/s, approaching that in vacuum, which is also in good agreement with 2.9672 × 108 m/s given by the numerical analysis with an uncertainty of 10−3. Our demonstration promises a key to hollow-core waveguide characterization for future wide-bandwidth and low-latency optical communication. [ABSTRACT FROM AUTHOR]

The determination of sulcus-to-sulcus measurements has been challenging due to the limitations of current approaches. Ultrasound methods are highly operator-dependent and require extensive training, while traditional optical devices cannot visualize structures posterior to the iris. However, modern optical anterior segment coherence tomography (AS-OCT) devices are changing this paradigm by identifying some anatomical landmarks posterior to the iris. This study evaluates the reproducibility of optical sulcus measurements in the context of sizing a novel accommodative intraocular lens (IOL). Preoperative OCT scans of patients scheduled for cataract surgery were analyzed regarding the dimensions of the ciliary sulcus using a custom scan method with a clinically available anterior segment optical coherence tomographer. Measurements were compared between two different readers, and various derived parameters were compared. The measurements by both readers were highly correlated (R2 > 0.96), and their agreement was excellent (mean difference 0.02 mm with 95% limits of agreement from −0.11 to 0.15 mm). In contrast, the sulcus diameter measurement did not agree well with automatically calculated values, such as the anterior chamber width or white-to-white. This leads to the conclusion that modern swept-source AS-OCT measurements of the ciliary sulcus dimensions are feasible, reproducible, and may be a clinically useful tool. [ABSTRACT FROM AUTHOR]

Femtosecond laser two-photon polymerization (TPP) technology, known for its high precision and its ability to fabricate arbitrary 3D structures, has been widely applied in the production of various micro/nano optical devices, achieving significant advancements, particularly in the field of photonic wire bonding (PWB) for optical interconnects. Currently, research on optimizing both the optical loss and production reliability of polymeric photonic wires is still in its early stages. One of the key challenges is that inadequate metrology methods cannot meet the demand for multiphysical measurements in practical scenarios. This study utilizes novel in situ scanning electron microscopy (SEM) to monitor the working PWBs fabricated by TPP technology at the microscale. Optical and mechanical measurements are made simultaneously to evaluate the production qualities and to study the multiphysical coupling effects of PWBs. The results reveal that photonic wires with larger local curvature radii are more prone to plastic failure, while those with smaller local curvature radii recover elastically. Furthermore, larger cross-sectional dimensions contribute dominantly to the improved mechanical robustness. The optical-loss deterioration of the elastically deformed photonic wire is only temporary, and can be fully recovered when the load is removed. After further optimization based on the results of multiphysical metrology, the PWBs fabricated in this work achieve a minimum insertion loss of 0.6 dB. In this study, the multiphysical analysis of PWBs carried out by in situ SEM metrology offers a novel perspective for optimizing the design and performance of microscale polymeric waveguides, which could potentially promote the mass production reliability of TPP technology in the field of chip-level optical interconnection. [ABSTRACT FROM AUTHOR]

The waveguide chip with a phase measurement function has garnered significant attention in the field of imaging optics, emerging as a crucial component in optical interferometric imaging systems. Enhancing the working bandwidth of these waveguide chips is essential for improving the imaging quality of interferometric systems. However, most existing designs primarily focus on narrow bands, with no reported research on broadband designs. This paper introduces a novel broadband waveguide chip design that incorporates a phase measurement function. We explore the fundamental structure and working principle of this innovative design. Fabricated on a silicon substrate, the chip features a silicon dioxide cladding layer and a germanium-doped silicon dioxide core layer, strategically optimized for performance. Utilizing the Beam Propagation Method (BPM), we conduct detailed simulations to determine the optimal device parameters. The simulation results demonstrate the effectiveness of our design, showing a phase measurement deviation of approximately 5° at a center wavelength of 1550 nm across a 300 nm wavelength range. The loss of the device is approximately 0.8 dB. These findings provide a solid foundation for future experimental implementations and fabrications, offering both a theoretical framework and technical reference for advancing the practical use of broadband waveguide chips with phase measurement functions in optical interferometric imaging. [ABSTRACT FROM AUTHOR]

D1244 in operation – first data and results on the way to controlled adaptation Global construction is responsible for about 50 % of the world's CO2‐emissions and resource consumption. For a sustainable future, a drastic reduction is required, which, however, is in contradiction to the worldwide demographics characterized by population increase and urbanization. One possible approach are adaptive load‐bearing structures equipped with distributed actuators and sensors that can manipulate deformations and stress distributions under loads through geometric adaptation. For high‐rise buildings, this technology enables a reduction of resource consumption by about 50 %, for example. The world's first prototype was inaugurated at the end of 2021 on the campus of the University of Stuttgart. With twelve floors on a base area of 5 m × 5 m, the D1244 is 36 m high and has 24 hydraulic actuators, 128 strain gauges, and an optical measurement system that uses two cameras to measure deformations at 16 points on the structure in a plane parallel to the camera sensor with submillimeter precision. This paper illustrates the steps within the model‐based development chain for automation and control of D1244 that have been accomplished and the results that have been achieved on this high‐rise building. The experimental model identification and the subsequent model‐based controller and observer design are discussed. Finally, the algorithms used for fault detection and diagnosis are presented and their basic functionality is demonstrated on the basis of initial validation measurements. [ABSTRACT FROM AUTHOR]

The MIllimeter Sardinia radio Telescope Receiver based on Array of Lumped elements KIDs, MISTRAL, is a cryogenic LEKID camera, operating in the W band ( 77 - 103 GHz ) from the Gregorian focus of the 64-m aperture Sardinia Radio Telescope (SRT), in Italy. This instrument features a high angular resolution ( ∼ 12 arcsec ) and a wide instantaneous field of view ( ∼ 4 arcmin ), allowing continuum surveys of the mm-wave sky with many scientific targets, including observations of galaxy clusters via the Sunyaev–Zel'dovich effect. In May 2023, MISTRAL has been installed at SRT for the technical commissioning. In this contribution, we will describe the MISTRAL instrument focusing on the laboratory characterization of its focal plane: a ∼ 400 -pixel LEKID array. We will show the optical performance of the detectors highlighting the procedure for the identification of the pixels on the focal plane, the measurements of the optical responsivity and NEP, and the estimation of the optical efficiency. [ABSTRACT FROM AUTHOR]

Background: Reliably calibrated criteria are needed for an accurate prediction of fracture of various components. However, there is not always a sufficient amount of material available. Therefore, miniature testing provides an alternative that is researched together with the following calibration of the ductile fracture criteria and investigating the size effect. Objective: The aim is to design miniature testing equipment and specimens for tensile testing, which covers various stress states. This is supplemented by the small punch test, which has the same specimen thickness, taken from the literature to broaden the portfolio for calibration. The second part deals with conducting the finite element analysis, which provided a basis for the calibration of the phenomenological ductile fracture criterion applicable to crack-free bodies to indicate the crack initiation. Methods: The steel frame to test thin specimens is designed with optical measurement of deformations. The finite element method is used, within Abaqus and user subroutines, to simulate the tests to obtain the variables needed for the calibration. In addition, the calibration of the criterion using machine learning is explored. Results: The feasibility of the proposed experimental program is tested on the aluminium alloy 2024-T351. Moreover, the numerical simulations, which showed a good match with experiments in terms of force responses, adds to the knowledge of modelling in the scope of continuum damage mechanics. Conclusions: The presented results provide a material basis for the aluminium alloy studied on a lower scale, while they broaden the testing possibilities and analyses the calibration strategies for the best failure predictability possible. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the anterior scleral thickness (AST) in patients with Marfan syndrome (MFS). Methods: A prospective, cross‐sectional study was conducted at the Department of Ophthalmology, Ghent University Hospital, Ghent, including patients with a genetically confirmed clinical diagnosis of MFS and age‐, gender‐ and axial length‐matched controls. Subjects with known corneal, conjunctival or scleral pathology and a history of ocular surgery, including pars plana vitrectomy, recent contact lens use or high‐grade astigmatism were excluded. Subjects underwent non‐cycloplegic autorefraction, Scheimpflug‐based corneal tomography, axial length measurement and spectral‐domain optical coherence tomography (OCT). AST was manually measured at 1 mm (AST1), 2 mm (AST2) and 3 mm (AST3) from the scleral spur, temporally and nasally. Results: A total of 56 subjects (28 subjects in the MFS group and 28 matched subjects in the control group) were included in this study. In patients with MFS, AST was significantly reduced compared to matched controls, both overall and at every analysed measuring point in the nasal and temporal areas (p < 0.001). Central corneal thickness (CCT) and mean keratometry (Kmean) values were significantly lower in patients with MFS (p < 0.05). A positive correlation was found between nasal AST and CCT in patients with MFS. No correlation was found between AST and Kmean or between AST and axial length. In patients with MFS with ectopia lentis, compared to those without, temporal AST3 was significantly lower (p < 0.05). AST was significantly lower in patients with MFS harbouring a variant predicted to cause haploinsufficiency compared to those with a variant expected to lead to a dominant negative effect for both nasal and temporal measurements. Conclusion: Based on anterior segment OCT measurements, AST of patients with MFS is significantly lower compared to matched controls. [ABSTRACT FROM AUTHOR]

Orbit determination using optical survey measurements for cataloging spacecraft encounters new obstacles from mega-constellations. These challenges arise from the sparse observations, and the frequent occurrences of unknown maneuvers which are difficult to model using traditional methods. By utilizing 14 Fourier coefficients, the Thrust-Fourier-Coefficients (TFC) model can effectively represent the averaged variations of orbital elements caused by arbitrary maneuvers. However, this model contains systematic offsets that will reduce the accuracy of orbit determination, and is unsuitable for spacecraft in nearly circular orbits. This paper first replaces the classical Keplerian elements of the previous TFC model with the nonsingular elements. Then detailed analytical expressions for model offsets have been derived based on Kozai's orbit-averaging method. A process noise covariance matrix related to the model offsets has been added to the iterated extended Kalman filter to compensate for the unmodeled dynamics and enhance the accuracy. Simulations based on this modified method demonstrate that the accuracy of orbit determination for maneuvering satellites can meet the requirements of catalog maintenance even with sparse observations. • A filtering-through approach is developed for orbit determination. • Thrust-Fourier-Coefficients gives equivalent trajectory of maneuvering target. • Nonsingular elements are used for spacecraft in nearly circular orbits. • Analytical expressions of dynamic model offset are derived by orbit-averaging method. • Adding process noise with model offset improves orbit determination accuracy. [ABSTRACT FROM AUTHOR]

In this study, Fe2O3 was introduced into sodium zinc-based phosphate glass, replacing Na2O. Using the conventional melt quenching technique, a glass system with the chemical composition 45P2O5 − 34ZnO − (21-x) Na2O - xFe2O3 (where, x = 1, 2, 3, 4, and 5 mol%) was prepared. X-ray diffraction (XRD) analysis showed that this substitution did not alter the glass's amorphous structure. However, the density increased slightly, potentially due to the higher molecular mass of Fe2O3 compared to Na2O. This density change suggests a possible alteration in the glass's optical properties. Optical measurements revealed a shift towards the red spectrum and a decrease in transmittance, particularly at 543 nm, indicating increased optical loss. This loss was attributed to increased reflectance, not absorption. The optical band gaps decreased with higher Fe2O3 content, enhancing the glass's optical resistance, and making it suitable for applications like optical filters and shielding materials. The optical loss tangent analysis showed that the material's efficiency in transmitting electromagnetic energy decreased with Fe2O3 substitution, likely due to changes in the electronic structure. The study also noted that Fe2O3 improved optical absorption, as demonstrated by the Hydrogenic Excitonic Model (HEM). [ABSTRACT FROM AUTHOR]

The study presents an investigation into the structural, morphological, and optical properties of nano-sized ZnO particles synthesized via the sol–gel method. We conducted a comprehensive examination of various operating parameters, including the choice of additive (citric or acetic acid) and the drying method. Our results indicate that the addition of acetic acid and drying with low-power microwave radiation yield high-quality nanoparticles. X-ray Diffraction (XRD) analysis revealed that the nanoparticles crystallize in the Würtzite hexagonal phase, even at high concentrations of acetic acid, without any indication of secondary phases or clusters, confirming the single-phase nature of the samples. Crystal structure analysis, performed using X-ray peak broadening and Williamson-Hall analysis, elucidated the contributions of crystallite size and lattice deformation to the broadening of peaks in the nanoparticles. Furthermore, Fourier Transform Infrared Spectroscopy measurements were employed to evaluate the chemical composition and phonon properties of the particles. Scanning Electron Microscopy images demonstrated a change in shape and size of the zinc oxide nanoparticles with increasing acetic acid concentration. Spectrophotometric measurements of optical properties revealed high reflectance and absorption in the visible range, with no significant variation in band gap energy. [ABSTRACT FROM AUTHOR]

The study assesses the efficacy of CeO2 nanoparticles synthesised via the hydrothermal method for UV‐induced catalytic activity in decomposing cobalt complexes. Various analyses, including X‐ray diffractometry (XRD), Raman spectroscopy, scanning electron microscopy (SEM), high‐resolution transmission electron microscopy (HR‐TEM), and UV‐Vis spectrophotometry were employed to investigate the impact of cobalt on cerium oxide's morphology, optical, electrochemical, and microstructural characteristics. The XRD analysis revealed a cubic structure in the fluorite‐type pattern, primarily oriented along the (111) direction. Raman spectroscopy supported these findings, identifying an active mode peak at 464 cm−1 and indicating the presence of F2g cubic fluorite. SEM imaging displayed cleavage and uniform, densely packed grains. Elemental analysis confirmed the presence of Ce, O, and Co, corroborated by X‐ray Photoelectron Spectroscopy (XPS) data. Optical measurements indicated a band gap starting at 3.03 eV, which decreased with increasing Co ratio, reaching 2.9 eV at 4 % cobalt incorporation. Furthermore, cyclic voltammetry experiments demonstrated that Co‐doped samples exhibited enhanced ion storage capacity. These comprehensive analyses underscore the potential of Co‐doped CeO2 nanoparticles for UV‐induced catalytic activity, offering valuable insights into their structural and functional properties. [ABSTRACT FROM AUTHOR]

Aim Method Results Conclusion To develop an accommodating, wide‐angle, schematic eye for emmetropia and myopia in which spectacle refraction and accommodation level are input parameters.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.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.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]

In this study, the first fabrication of phase‐shifted Bragg gratings utilizing chalcogenide hybrid inorganic/organic polymers (CHIPs) is presented based on poly(sulfur‐random‐(1,3‐isopropenylbenzene) to measure the thermo‐optic coefficient (TOC) of this new class of optical polymers. The unique properties of CHIPs, such as high index contrast and low optical losses, are leveraged to fabricate Bragg gratings that enable precise determination of the TOC and glass transition temperature (Tg) of these polymers. The optical measurement introduces a novel technique to measure the TOC and Tg of optical polymers which can be difficult to determine using traditional methods such as differential scanning calorimetry (DSC) after fabrication into photonic device constructs. The findings demonstrate that CHIPs exhibit low thermo‐optic (TO) effects, making them exceptionally well‐suited for the development of thermally stable photonic integrated circuits. [ABSTRACT FROM AUTHOR]

We explore the influence of radio-mode feedback on the properties of the cool circumgalactic medium (CGM). To this end, we assemble a statistical sample of approximately 30,000 radio galaxies with background quasars by combining optical spectroscopic measurements of luminous red galaxies and quasars from the year 1 data set of the Dark Energy Spectroscopic Instrument and radio sources from the LOw-Frequency ARray Two-metre Sky Survey (LoTSS) DR2 catalog and the Very Large Array Sky Survey (VLASS) quick-look catalog. Galaxies with similar optical properties but with no radio counterparts in LoTSS and VLASS are selected as the control group. We measure the cool CGM properties of radio galaxies and their control samples traced by Mg ii absorption lines, including covering fraction, rest equivalent width, and gas kinematics. Our results show no significant difference in the properties of gas around radio galaxies and their control sample, indicating that the operating radio-mode feedback of massive galaxies does not produce detectable effects on the properties of the cool CGM. Finally, we show that the CGM of radio galaxies contains a nonnegligible amount of cool gas with approximately 1010 M ⊙. This abundance can place a stringent constraint on the radio-mode feedback models. [ABSTRACT FROM AUTHOR]

This paper presents an 8 × 8 channel optoelectronic readout array (ORA) realized in the TSMC 180 nm 1P6M RF CMOS process for the applications of short-range light detection and ranging (LiDAR) sensors. We propose several circuit techniques in this work, including an amplitude-to-voltage (A2V) converter that reduces the notorious walk errors by intensity compensation and a time-to-voltage (T2V) converter that acquires the linear slope of the output signals by exploiting a charging circuit, thus extending the input dynamic range significantly from 5 μApp to 1.1 mApp, i.e., 46.8 dB. These results correspond to the maximum detection range of 8.2 m via the action of the A2V converter and the minimum detection range of 56 cm with the aid of the proposed T2V converter. Optical measurements utilizing an 850 nm laser diode confirm that the proposed 8 × 8 ORA with 64 on-chip avalanche photodiodes (APDs) can successfully recover the narrow 5 ns light pulses even at the shortest distance of 56 cm. Hence, this work provides a potential CMOS solution for low-cost, low-power, short-range LiDAR sensors. [ABSTRACT FROM AUTHOR]

An image is a visual representation that can be used to obtain information. A camera on a moving vector (e.g., on a rover, drone, quad, etc.) may acquire images along a controlled trajectory. The maximum visual information is captured during a fixed acquisition time when consecutive images do not overlap and have no space (or gap) between them. The images acquisition is said to be anomalous when two consecutive images overlap (overlap anomaly) or have a gap between them (gap anomaly). In this article, we report a new algorithm, named OVERGAP, that remove these two types of anomalies when consecutive images are obtained from an on-board camera on a moving vector. Anomaly detection and correction use here both the Dynamic Time Warping distance and Wasserstein distance. The proposed algorithm produces consecutive, anomaly-free images with the desired size that can conveniently be used in a machine learning process (mainly Deep Learning) to create a prediction model for a feature of interest. [ABSTRACT FROM AUTHOR]

Measurements of areal (3D) surface texture using optical methods are very popular because of the short measurement time compared to the stylus tip technique. However, they are very sensitive to measurement errors. In some cases, optical measurements are not recommended. The stylus measurement method is well known and can be the reference technique for surface texture measurement. The main disadvantage is the long measuring time. This time can be shortened using higher speeds of measurement. The effect of the speed of the measurement of stylus profilometer on changes in surface texture parameters was studied. Fifty surface topographies were measured using the stylus profilometer at speeds 0.5, 1, 2, 3, 4, and 5 mm/s in the same places. Surfaces after lapping, polishing, grinding, milling, laser texturing, and two-process random surfaces were measured and analyzed. Changes in parameters caused by the increase in the traverse speed depend on the characteristics and parameters of the surfaces. The random surfaces changed more than the deterministic ones. The increase in the traverse speed from 0.5 to 1 mm/s caused small changes in the parameters. [ABSTRACT FROM AUTHOR]

High-frequency optical dynamic measurement can realize multiple measurement points covering the whole surface of the thin-walled structure, which is very useful for obtaining high-resolution spatial information for damage localization. However, the noise and low calculation efficiency seriously hinder its application to real-time, online structural health monitoring. To this end, this paper proposes a novel high-resolution frequency domain decomposition (HRFDD) modal identification method, combining an optical system with an accelerometer for measuring high-accuracy vibration response and introducing a clustering algorithm for automated identification to improve efficiency. The experiments on the cantilever aluminum plate were carried out to evaluate the effectiveness of the proposed approach. Natural frequency and damping ratios were obtained by the least-squares complex frequency domain (LSCF) method to process the acceleration responses; the high-resolution mode shapes were acquired by the singular value decomposition (SVD) processing of global displacement data collected by high-speed cameras. Finally, the complete set of the first nine order modal parameters for the plate within the frequency range of 0 to 500 Hz has been determined, which is closely consistent with the results obtained from both experimental modal analysis and finite element analysis; the modal parameters could be automatically picked up by the DBSCAN algorithm. It provides an effective method for applying optical dynamic technology to real-time, online structural health monitoring, especially for obtaining high-resolution mode shapes. [ABSTRACT FROM AUTHOR]