Optical Monitoring Research Articles

Drift Error Compensation Algorithm for Heterodyne Optical Seawater Refractive Index Monitoring of Unstable Signals.

The refractive index measurement of seawater has proven significance in oceanography, while an optical heterodyne interferometer is an important, highly accurate, tool used for seawater refractive index measurement. However, for practical seawater refractive index measurement, the refractive index of seawater needs to be monitored for long periods of time, and the influence of drift error on the measurement results for these cases cannot be ignored. This paper proposes a drift error compensation algorithm based on wavelet decomposition, which can adaptively separate the background from the signal, and then calculate the frequency difference to compensate for the drift error. It is suitable for unstable signals, especially signals with large differences between the beginning and the end, which is common in actual seawater refractive index monitoring. The authors identify that the primary cause of drift error is the frequency instability of the acousto-optic frequency shifter (AOFS), and the actual frequency difference was measured through experimentation. The frequency difference was around 0.1 Hz. Simulation experiments were designed to verify the effectiveness of the algorithm, and the standard deviation of the optical length of the results was on the scale of 10-8 m. Liquid refractive index measurement experiments were carried out in a laboratory, and the measurement error was reduced from 36.942% to 0.592% after algorithm processing. Field experiments were carried out regarding seawater refractive index monitoring, and the algorithm-processing results are able to match the motion of the target vehicle. The experimental data were processed with different algorithms, and, according to the comparison of the results, the proposed algorithm performs better than other existing drift error elimination algorithms.

Elucidating key mechanistic processes during acidic CO2 electroreduction on gas diffusion electrodes towards stable production of formic acid

The electrochemical reduction of CO2 using renewable electricity could be a sustainable alternative to produce formic acid. Although using bulk acidic electrolyte offers system and downstream processing benefits, neutral to alkaline electrolyte systems prevail due to challenge suppressing hydrogen evolution in acidic environment. In recent years, it has been shown that HER could be mitigated by confining the OH- being generated and constraining the movement of H3O+ towards reaction surface, thereby producing an alkaline reaction environment within the electrode. Herein, we have demonstrated how a porous and highly hydrophobic Bi-based gas diffusion electrode enables remarkably efficient bulk acidic electrolysis. Importantly, the local alkaline reaction environment has been proven via electrochemical impedance spectroscopy and pH visualization. Furthermore, optical monitoring of electrolyte conditions through a transparent cell sheds light on the CO2 recovery process in the acidic system, promoting a better technical practice in handling with electrochemical cells and CO2 recirculation. Finally, HCOOH accumulation as the key degradation reason is unveiled through investigation into the impact of operating modes on the stability at high current density, where earlier studies failed to adequately address. It is believed that this valuable insight could facilitate stable and efficient formic acid production in future work.

Programming multilevel crystallization states in phase-change-material thin films

We propose and demonstrate a simple method to accurately monitor and program arbitrary states of partial crystallization in phase-change materials (PCMs). The method relies both on the optical absorption in PCMs as well as on the physics of crystallization kinetics. Instead of raising temperature incrementally to increase the fraction of crystallized material, we leverage the time evolution of crystallization at constant temperatures and couple this to a real-time optical monitoring to precisely control the change of phase. We experimentally demonstrate this scheme by encoding a dozen of distinct states of crystallization in two different PCMs: GST and Sb2S3. We further exploit this ’time-crystallization’ for the in-situ analysis of phase change mechanisms and demonstrate that the physics of crystallization in Sb2S3 is fully described by the so-called Johnson-Mehl-Avrami-Kolmogorov formalism. The presented method not only paves the way towards real-time and model-free programming of non-volatile reconfigurable photonic integrated devices, but also provides crucial insights into the physics of crystallization in PCMs.

Application of machine learning to object manipulation with bio-inspired microstructures

Bioinspired fibrillar adhesives have been proposed for novel gripping systems with enhanced scalability and resource efficiency. Here, we propose an in-situ optical monitoring system of the contact signatures, coupled with image processing and machine learning. Visual features were extracted from the contact signature images recorded at maximum compressive preload and after lifting a glass object. The algorithm was trained to cope with several degrees of misalignment and with unbalanced weight distributions by off-center gripping. The system allowed an assessment of the picking process for objects of various mass (200, 300, and 400 g). Several classifiers showed a high accuracy of about 90 % for successful prediction of attachment, depending on the mass of the object. The results promise improved reliability of handling objects, even in difficult situations.

Deep learning object detection for optical monitoring of spatters in L-PBF

Deep learning object detection for optical monitoring of spatters in L-PBF

Frameless LINAC-Based Stereotactic Radiosurgery is Safe and Effective for Essential and Parkinsonian Tremor

Stereotactic radiosurgery (SRS) to the thalamus is an ablative technique used for treatment of refractory tremor of essential or Parkinsonian origin. Because of the high dose, small target, and required precision, framed SRS on the Gamma Knife has been the historical platform of choice. We tested our recently developed technique to emulate GK dose distributions on a multi-leaf collimator (MLC)-equipped linear accelerator (LINAC) without cumbersome, inefficient cones in a prospective trial of safety and efficacy. We quantified pre-treatment contralateral tremor according to FTM scoring system. We obtained MPRAGE, FGATIR, DTI, and RS-fMRI sequences. We identified the VIM via classical stereotactic reference location and connectomically, and then targeted it to 135 Gy dmax in a manner dosimetrically roughly equivalent to 4 mm GK shot. We adjusted each target such that the 25 Gy isodose line did not overlap the posterior limb of the capsule. We immobilized patients in a highly rigid thermoplastic mask and delivered treatment on an Edge™ LINAC with HDMLC. Intrafraction optical surface monitoring (OSMS) ensured patient immobility. We surveilled post-treatment imaging and recorded tremor scoring, QOL outcomes, and adverse events. We accrued 42 patients (16 female, 26 males; median age 72.5) over 36 months. 38 had essential tremor, 4 had tremor-dominant Parkinson's; 2 withdrew prior to treatment. Ten patients were on therapeutic anti-coagulation, and were not required to discontinue. At time of submission 39 patients had follow-up ≥ 6 months. 35/39 (89.7%) exhibited clinically meaningful tremor reduction. Mean limb tremor reduction among responders was 43.5% (range: 9 - 100%). Time to patient-reported tremor improvement was 0.3 to 15 months. One patient experienced Gr 3, and 4 patients experienced Gr 1-2 toxicity. MLC-based SRS thalamotomy is safe and effective for refractory tremor treatment. Multidisciplinary management is key for proper patient selection, treatment, and monitoring. Our outcomes appear congruent to historical GK controls as well as more modern MRgFUS outcomes.

Variation in Left Anterior Descending Coronary Artery Accumulated Dose Estimates during Breast Cancer Radiotherapy

Left anterior descending (LAD) coronary artery RT dose has been associated with the risk of coronary ischemic events in patients with breast cancer treated with radiotherapy (RT). However, consensus dose constraints commonly utilize mean heart dose, which has been shown to be an inadequate surrogate for LAD dose. Given the LAD is adjacent to the steep dose gradients of the left breast/chest wall, we hypothesize that variations in patient positioning or depth of breath hold may contribute to significant deviations in daily LAD dose exposure compared to predicted. Our objective was to investigate variations in accumulated LAD dose in patients with left-sided breast cancer treated with RT. Retrospective analysis of 10 consecutive patients with left-sided breast cancer treated between 2019-2022 with volumetric modulated arc therapy (VMAT) in the supine position. RT was delivered using daily cone beam computed tomography (CBCT) image guidance with deep-inspiratory breath hold technique and an optical surface monitoring system. Daily CBCT scans were individually registered to each planning CT based on daily positional changes. The LAD was manually segmented and transformed to each CBCT. Daily fractional dose was calculated (mean, volume receiving 15 Gy [V15 Gy], V30 Gy, and max) and summed to produce an accumulated dose which was compared to the predicted dose. Significant deviations in accumulated dose were defined as at least ±15% from predicted. The RT targets included breast/chest wall only (n = 1), supraclavicular nodes (n = 8), and/or internal mammary chain (n = 5). All plans were prescribed to 50 Gy in 25 fractions. The median predicted mean heart dose was 5.1 Gy. Overall, there were no significant differences between the median predicted vs. accumulated LAD doses: mean 10.4 vs. 10.2 Gy, V15 Gy 21% vs. 25%, V30 Gy 0% vs. 1%, max 24.5 vs 25.7 Gy (all p>.05). However, there was a subset of patients (n = 5, 50%) with significant deviations in accumulated vs. predicted dose (at least ±15%). For LAD mean, n = 2 had higher accumulated vs. predicted doses (16.6 vs. 11.6 Gy; 14.6 vs. 12.8 Gy), while n = 3 had lower (21.8 vs. 26.5 Gy; 2.7 vs. 4.2 Gy; 13.9 vs. 16.5 Gy). For LAD V15 Gy, n = 3 had higher accumulated vs. predicted doses (43 vs. 35%; 51% vs. 25%; 14% vs. 9%), while n = 2 had lower (49% vs. 61%; 37% vs. 56%). For LAD V30 Gy, n = 4 had higher accumulated vs. predicted doses (12% vs. 5%; 5% vs. 0%; 4% vs. 0%; 4% vs. 2%), while n = 1 had lower (32% vs. 44%). Daily setup differences, including the extent of inspiratory breath hold, may contribute to deviations in accumulated LAD dose (more than 15% of predicted) in approximately half of patients and were more pronounced in V15 and V30 Gy metrics. The potential for significant LAD dose uncertainty in a clinically meaningful subset of patients should be recognized and warrants further analysis in an expanded cohort.

Prospective Evaluation of Implementation of a Tattoo-less Workflow for Non-Spine Bone SBRT

Oligometastatic disease has expanded the clinical indications for non-spine bone (NSB) SBRT. Optical surface monitoring systems (OSMS) may reduce treatment time if it represents an effective surrogate for bone intrafraction motion monitoring. We aimed to identify whether OSMS could substitute for 2D-3D mid-imaging and enable a tattoo-less set up in NSB SBRT. Beginning 11/2019, OSMS was incorporated in parallel with an existing workflow using CBCT and mid 2D-3D kV/kV imaging for pre- and mid-imaging for NSB SBRT. The ability of OSMS to detect both observed out-of-tolerance (>2mm/>2deg) shifts and manual couch shifts was analyzed. A workflow incorporating OSMS reference captures, CBCT for pre-treatment verification and OSMS/triggered imaging (TI) for intrafraction monitoring was developed and deployed for rib/sternum SBRT beginning 11/2021 and all NSB SBRT beginning 2/2022. All NSB SBRT treatment appointments were analyzed through statistical process control (SPC) with use of an XmR chart of average set up and total treatment time per quarter from 2/2019 to 2/2023. Special cause rules were based on IHI rules and conduced with spreadsheet software. From 2/2019 to 2/2023, 1962 NSB SBRT fractions were delivered, including 337 rib, 150 sternum, 197 femur, 266 ilium, 222 multi-site. Over 104 femur and 87 ilium images, there were no over tolerance intra-fraction events detected with 2D-3D or OSMS. Over 20 manual shifts, OSMS could detect 2mm shifts to within 0.4mm 67% of the time and 0.8mm 95% of time. There was no difference in treatment set up time following adoption of an OSMS/TI workflow as a replacement for 2D-3D mid-imaging. A reduction in rib SBRT delivery and multi-site treatment set-up times was significantly associated with the adoption of OSMS/TI and OSMS, respectively, as assessed based on special cause variation with 8 consecutive points below the mean. Integration of OSMS and triggered imaging has enabled the transition to a completely tattoo-less workflow, thus sparing patients the need for permanent tattoos whilst also allowing more continuous motion monitoring and reduced radiation exposure related to unnecessary 2D-3D or CBCT mid-imaging. Treatment times were significantly reduced for patients receiving rib SBRT or multi-site NSB SBRT with this workflow.

Clinical Implementation of Optical Surface Imaging Systems in Vulvar Cancer to Reduce Setup Error

Optical surface monitoring system (OSMS) could achieve continuous monitoring of patient position through a nonradiographic and noninvasive technology, which has been widely applied to many sites of radiation therapy including breast, intracranial, head and neck, abdomen, and the extremities. However, no study has investigated the application of OSMS in radiation therapy of vulvar cancer. In this study, we hypothesized using OSMS would reduce setup error in the vulvar cancer compared to standard laser-based setup (SLS). A single-center prospective trial included 10 patients with vulvar cancer treated with intensity modulated radiation therapy (IMRT) for a total of 250 fractions. Every patient was immobilized with Styrofoam in a frog-leg position and used marks on the patient's skin to align to the room lasers for pre-setup. The treatment couch values of lateral (Lat), longitudinal (Lng), vertical (Vrt) in three translation directions and Rtn (the rotation along the z axis), Pitch (the rotation along the x axis), Roll (the rotation along the y axis) in three rotations directions were recorded. Then completed the setup of patient with information from a surface imaging system and obtained deviation values. Setup is followed by pretreatment cone-beam computed tomography (CBCT) to further verify patient and target position by registering to the planning CT with respect to bony anatomy. With CBCT as a gold standard for patient setup, the absolute values of setup error and error distribution of SLS method and OSMS method from the same patient in above six directions were compared. The mean of absolute values of setup errors in the SLS method were significantly higher than those of OSMS method in Lat (0.34cm vs 0.20cm), Lng (0.42cm vs 0.29cm), Vrt (0.43cm vs 0.28cm) and Rtn (0.90° vs 0.67°) directions (P<0.05). The mean errors in SLS and OSMS methods in Pitch and Roll directions were 0.93° and 1.02° (P = 0.16), 0.42° and 0.45° (P = 0.48), respectively, with no significant difference. In the OSMS method, the distribution rates of the setup errors within 0.5cm in three translation directions and within 1.5° in three rotations directions were significantly higher in Lat (90.8% vs 80.4%), Lng (82.0% vs 68.8%), Vrt (83.2% vs 65.6%), and Rtn (91.2% vs 80.4%) directions than those of SLS method (P<0.05). In the Pitch (79.2% vs 80.4%) and Roll (97.2% vs 98.0%) directions, the distribution rates of the OSMS method were slightly lower than those of the SLS method, with no significant difference (P = 0.738 and P = 0.559). The implementation of OSMS in IMRT for vulvar cancer could reduce setup error and increase precision of setup, especially for the directions of Lat, Lng, Vrt and Rtn.

Real-time optical monitoring of non-isothermal bleaching of γ-irradiated International Simple Glass (ISG)

The thermal bleaching of γ-irradiated (0.83 and 1.99 MGy) nuclear waste glass simulant known as International Simple Glass (ISG, made by Mo-SCI Corporation, Rolla, MO) was studied in real time by non-isothermal in situ UV/Vis optical microspectroscopy. The method follows the Urbach energy temperature/time evolution for three constant heating rates. A novel opto-thermal technique for kinetic analysis, coined temperature scanning bleaching spectroscopy (TSBS) is proposed. The applicability of the Kissinger equation is extended by synergistic inflection point analysis of the Urbach energy time/temperature sigmoid. The sigmoidal behavior is discussed in the context of polaron time/temperature trends of the main factors of thermally generated polaron flux. The overall activation energy of the non-isothermal thermal bleaching is evaluated at 1.6 (±0.1) and 1.3 (±0.2) eV, for 0.83 and 1.99 MGy, respectively. The proposed TSBS methodology is applicable for real-time monitoring and robust quantitative comparison of non-isothermal thermal bleaching of any glassy material.

Plasmonic hot electron-induced WO3 films for a highly responsive visible photodetector

Visible photodetectors have found significant applications in various fields that require rapid and precise detection of visible light. These fields encompass optical communication, high-speed imaging, LIDAR systems, biomedical imaging, and industrial process monitoring. Semiconductors play a crucial role in photodetection applications by efficiently converting light into electrical signals, offering high sensitivity and rapid response time. Among various semiconductor metal oxides, WO3 is commonly used as a visible photodetector due to its unique properties like high chemical & thermal stability, and it possesses a direct bandgap making it suitable for efficient detection of visible light. Here we report the surface plasmon resonance induced visible light detection using Au NPs on WO3 film. The WO3 film was grown on SiO2 substrate by DC magnetron sputtering while monodispersed (⁓20 nm) Au NPs were chemically synthesised. MSM based Au NPs functionalized WO3 film was tested under 455 nm wavelength with changing optical power and applied bias. The interaction of Au NPs and visible light lead to generation of hot electrons leading to enhancement in the photocurrent. The fabricated device exhibits large bias-dependent responsivity, low NEP, and high EQE of 23.45 A/W, 2.6 × 10−13 WHz−1/2, and 126%, respectively. The study not only provides understanding of plasmon-enhanced visible light detection but also underscores the significance of Au NPs as a powerful tool for enhancing the performance of WO3-based visible photodetectors. The implications of this study extend beyond fundamental research, paving the way for novel applications in the field of optoelectronics appliances.

Non-Invasive Continuous Optical Monitoring of Cerebral Blood Flow after Traumatic Brain Injury in Mice Using Fiber Camera-Based Speckle Contrast Optical Spectroscopy.

Neurocritical care focuses on monitoring cerebral blood flow (CBF) to prevent secondary brain injuries before damage becomes irreversible. Thus, there is a critical unmet need for continuous neuromonitoring methods to quantify CBF within the vulnerable cortex continuously and non-invasively. Animal models and imaging biomarkers can provide valuable insights into the mechanisms and kinetics of head injury, as well as insights for potential treatment strategies. For this purpose, we implemented an optical technique for continuous monitoring of blood flow changes after a closed head injury in a mouse model, which is based on laser speckle contrast imaging and a fiber camera-based approach. Our results indicate a significant decrease (~10%, p-value < 0.05) in blood flow within 30 min of a closed head injury. Furthermore, the low-frequency oscillation analysis also indicated much lower power in the trauma group compared to the control group. Overall, blood flow has the potential to be a biomarker for head injuries in the early phase of a trauma, and the system is useful for continuous monitoring with the potential for clinical translation.

Non-contact optical spectroscopy for tumor-sensitive diffuse reflectance and fluorescence measurements on murine subcutaneous tissue models: Monte Carlo modeling and experimental validations.

Fiber-optic probes are commonly used in biomedical optical spectroscopy platforms for light delivery and collection. At the same time, it was reported that the inconsistent probe-sample contact could induce significant distortions in measured optical signals, which consequently cause large analysis errors. To address this challenge, non-contact optical spectroscopy has been explored for tissue characterizations. However, existing non-contact optical spectroscopy platforms primarily focused on diffuse reflectance measurements and may still use a fiber probe in which the probe was imaged onto the tissue surface using a lens, which serves as a non-contact probe for the measurements. Here, we report a fiber-probe-free, dark-field-based, non-contact optical spectroscopy for both diffuse reflectance and fluorescence measurements on turbid medium and tissues. To optimize the system design, we developed a novel Monte Carlo method to simulate such a non-contact setup for both diffuse reflectance and fluorescence measurements on murine subcutaneous tissue models with a spherical tumor-like target. We performed Monte Carlo simulations to identify the most tumor-sensitive configurations, from which we found that both the depth of the light focal point in tissue and the lens numerical aperture would dramatically affect the system's tumor detection sensitivity. We then conducted tissue-mimicking phantom studies to solidify these findings. Our reported Monte Carlo technique can be a useful computational tool for designing non-contact optical spectroscopy systems. Our non-contact optical setup and experimental findings will potentially offer a new approach for sensitive optical monitoring of tumor physiology in biological models using a non-contact optical spectroscopy platform to advance cancer research.

Effectiveness of a vision-based handle trajectory monitoring system in studying robotic suture operation.

Data on surgical robots are not openly accessible, limiting further study of the operation trajectory of surgeons' hands. Therefore, a trajectory monitoring system should be developed to examine objective indicators reflecting the characteristic parameters of operations. 20 robotic experts and 20 first-year residents without robotic experience were included in this study. A dry-lab suture task was used to acquire relevant hand performance data. Novices completed training on the simulator and then performed the task, while the expert team completed the task after warm-up. Stitching errors were measured using a visual recognition method. Videos of operations were obtained using the camera array mounted on the robot, and the hand trajectory of the surgeons was reconstructed. The stitching accuracy, robotic control parameters, balanceanddexterityparameters, and operation efficiency parameters were compared. Experts had smaller center distance (p < 0.001) and larger proximal distance between the hands (p < 0.001) compared with novices. The path and volume ratios between the left and right hands of novices were larger than those of experts (both p < 0.001) and the total volume of the operation range of experts was smaller (p < 0.001). The surgeon trajectory optical monitoring system is an effective and non-subjective method to distinguish skill differences. This demonstrates the potential of pan-platform use to evaluate task completion and help surgeons improve their robotic learning curve.

Enhanced spectroelectrochemistry with lossy-mode resonance optical fiber sensor

Spectroelectrochemical (SEC) measurements play a crucial role in analytical chemistry, utilizing transparent or semitransparent electrodes for optical analysis of electrochemical (EC) processes. The EC readout provides information about the electrode's state, while changes in the transmitted optical spectrum help identify the products of EC reactions. To enhance SEC measurements, this study proposes the addition of optical monitoring of the electrode. The setup involves using a polymer-clad silica multimode fiber core coated with indium tin oxide (ITO), which serves as both the electrode and an optical fiber sensor. The ITO film is specifically tailored to exhibit the lossy-mode resonance (LMR) phenomenon, allowing for simultaneous optical monitoring alongside EC readouts. The LMR response depends on the properties of the ITO and the surrounding medium's optical properties. As a result, the setup offers three types of interrogation readouts: EC measurements, optical spectrum analysis corresponding to the volume of the analyte (similar to standard SEC), and LMR spectrum analysis reflecting the state of the sensor/electrode surface. In each interrogation path, cyclic voltammetry (CV) experiments were conducted individually with two oxidation–reduction reaction (redox) probes: potassium ferricyanide and methylene blue. Subsequently, simultaneous measurements were performed during chronoamperometry (CA) with the sensor, and the cross-correlation between the readouts was examined. Overall, this study presents a novel and enhanced SEC measurement approach that incorporates optical monitoring of the electrode. It provides a comprehensive understanding of EC processes and enables greater insights into the characteristics of the analyte.

Characterization for three-dimensional stress of roadway roof through physics-informed neural network on monitoring data

Characterizing the mechanical status of underground engineering is crucial for preventing structural disasters and ensuring safe operation. However, it is difficult to sense the three-dimensional stress of the whole structure due to the limitation of sensor and monitoring technology, and the existing sensing methods lack the support of mechanical mechanism. Therefore, we aim to develop a three-dimensional stress sensing method for the whole roadway roof using an energy modified physics-informed neural network (EPINN) on sparse fiber optical monitoring data. First, the sensor monitoring and numerical simulation are used to provide structural mechanical information. Then, EPINN is formulized on the sparse monitoring data and constricted by the physical correlations captured from numerical simulation. Moreover, the strain energy is adopted to modify the pure data-driven model. To indicate the reliability of the presented model, the on-site experiment and the comparison experiments with some widely used models are conducted. Experimental results show that EPINN model can better characterize the overall stress distribution of roadway roof, and the sensing error is much smaller than the existing model. The method is reliable.

Investigation of the effect of Mo+2 ion concentration on linear and non-linear optical properties of tungsten trioxide thin films for optoelectronic applications

To achieve the goal of creating a single-phase mixture of transition metal oxides with high electrical efficiency, our investigation focused on studying the linear and nonlinear optical properties of a mixture of transitional oxides that is electrophoretically colored. For finding the best ratios, we also investigated the impact of adding molybdenum ion to tungsten trioxide on the linear and non-linear optical properties of the samples made using the spray pyrolysis method on heated glass substrates. The as-deposited films were amorphous, as demonstrated by the X-ray diffraction (XRD). All of the samples were transferred to the polycrystalline and acquire a triclinic structure after the thermal annealing at 500 °C for 2 h. At room temperature, transmission and reflection measurements in the wavelength range of 300–2500 nm were utilized to evaluate the absorption coefficient. MoxW1-xO3 thin films' optical density, optical energy gap, skin depth, and Urbach's parameters were also estimated. Urbach's energy, EU, decreases from 0.355 to 0.154, eV as Mo-content rises, while Tauc's band gap energy, Eg, decreases from 2.76 to 2.56 eV. The films' static refractive indices dropped from 2.832 to 2.081 in the low-energy region and from 3.832 to 2.446 in the high-energy region. The dispersion energies and other variables were investigated using the Wemple–DiDomenico and Sellmeier models. In addition, various dispersion and nonlinear parameters were estimated and thoroughly discussed. It was observed that the improvement in the crystallinity of W1-xMoxO3 thin films led to a decrease in the values of the third-order nonlinear susceptibility (χ(3)), mainly affected by the constant refractive index, which decays with an increase in Mo concentration. Simultaneously, the conductivity of the films rises proportionally with the photon energy and Mo content, which is attributed to the concurrent increase in the dielectric constants. In this work, new approach for fabrication of quality thin film of MoxW1-xO3 was demonstrated. This is the reason for obtaining the best results, which made these films an effective contribution to many important applications. Furthermore, MoxW1-xO3 thin films perovskite has large nonlinear optical proper. These findings highlight the potential utility of these films in diverse critical optical applications, such as commercial lasers, ultra-fast signal processing in optical communication systems, sensors, environmental monitoring, medicine, manufacturing and materials processing, military applications, as well as scientific instrumentation.

A novel multifunctional fluorescent capillary-based sensor for simultaneous monitoring of pH, O2 and CO2

A fluorescent capillary sensor for detecting the bioanalytically and biologically relevant analytes pH, O2, and CO2 has been designed. The sensor is based on single capillary tube with 2 mm inner diameter, which is simultaneous doped with emissive O2-sensitive indicator Ru(dpp)3(PF6)2 (RuDP), pH-sensitive and CO2-sensitive indicator 8-hydroxypyrene-1, 3,6-trisulfonic acid trisodium salt (HPTS). The multifunctional sensor can be excited at the same wavelength and realize multi-parameter optical monitoring at the different sensing position. Studies in phosphate-buffered solutions display the excellent feasibility of the capillary sensor for fluorescence detection of pH, O2, and CO2. Overall, the multifunctional capillary sensor exhibits great potential in real-time blood gas analysis, and clinical application of multi-parameter biological detection.

Multi-sensor monitoring of powder melting states via melt pool optical emission signals during laser-based powder bed fusion

The instability of the powder melting states is a common problem in laser-based powder bed fusion of metals (PBF-LB/M). Optical signal monitoring based on melt pool emissions has great potential to solve this problem, but there is a lack of research on the inherent correlations between the optical emissions and powder melting states. In this paper, a synchronous monitoring method of multi-sensor signals based on automatic trigger by numerical control programming was proposed. Then the relationships between the characteristic changes in melt pool signals and the powder melting state variations were carefully examined based on the statistical method. The results showed that the data collection method achieved synchronous monitoring of multi-sensor signals in the target process. The combination of the melt pool light intensity and melt pool area can effectively capture powder melting state variations owing to the changes of powder thickness. Among them, the melt pool light intensity can accurately monitor powder melting state variations caused by the powder thickness of 30 μm to 210 μm. While the melt pool area is susceptible to powder melting state variations caused by the powder thickness of 210 μm to 300 μm. Meanwhile, two emission characteristics (mean intensity and standard deviation) of the optical emissions were closely related to the melting states and stability of the powder.

Distributed optical fiber sensing technology in operation status monitoring of GIL equipment

Abstract This paper firstly proposes distributed fiber optic sensing technology based on big data technology and physics, distributed fiber optic sensing technology includes distributed fiber optic sensing technology based on interference type and distributed fiber optic sensing technology based on the scattering principle. Then investigated the demand for remote monitoring of distributed fiber optic sensing systems and the demand for large sensing networks in the Internet of Things and designed a long-distance distributed fiber optic sensing-based intelligent monitoring system. Finally, the vibration acceleration signal of the metal shell when partial discharge occurs is collected, and the high-frequency components in the vibration acceleration signal are used to diagnose and analyze the discharging faults caused by the metal particles of GIL. The results show that: when the rated current is loaded on the GIL, the main frequency distribution of the vibration acceleration signal on the surface of the metal shell is from 0 to 1 kHz, and the percentage of the signal energy in this frequency band is greater than 99% of the total energy in the range of 0 to 20 kHz. In the frequency range of 1 kHz to 20 kHz, the percentage of the signal energy in the total energy does not exceed 1%, and there is almost no high-frequency vibration acceleration signal. This study and the combination of these two technologies is a great contribution to the further development of each, but also more favorable for application in work and life.