This PDF file contains the front matter associated with SPIE Proceedings Volume 13417, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

This article analyzes the structure and measurement principle of ultrasonic Doppler fetal heartbeat detector, based on YY/T 0749-2009 Ultrasonic -- Hand-held probe Doppler fetal heartbeat detectors -- Performance requirements and method of measurement and reporting and other standards and technical specifications, studies and determines the key technical indicators that affect the metrological performance of ultrasonic Doppler fetal heartbeat detector, puts forward an novel and effective metrological traceability method to measure fetal heartbeats at different detection depths in order to accurately evaluate the metrological performance of fetal heartbeat detectors, and evaluates the uncertainty of fetal heartbeat measurement error, providing a reliable metrological technical support for ensuring the quality of ultrasonic Doppler fetal heartbeat detector.

In the design process of elliptical gear flowmeter, the design of elliptical gear pair is crucial. The problems to be solved are mainly the design of the second-order elliptic pitch curve and the design of the gear tooth profile. In this paper, the elliptical gear is theoretically analysed, a new design idea is provided, and the design of the second-order elliptic pitch curve is achieved by using MATLAB as the programming calculation programming tool, and the tooth profile of the elliptical gear is trimmed by using KISSsoft. The strength analysis of the elliptical gear is carried out through simulation experiments, and the good meshing of the elliptical gear pair is verified by using the accuracy test of the flowmeter. The rationality and feasibility of the design idea are finally confirmed.

The Quadrant Detector (QD) is widely used in the fields of guidance and tracking. This paper investigates the effect of the dead zone width of QD on tracking accuracy. A spot centroid calculation model considering the dead zone of QD is established based on Gaussian spot, and Gaussian distributed noise is introduced to build a measurement error model of QD under noise interference. To verify the accuracy of the model, numerical calculations and comparative analysis of the standard deviation of the measurement error are conducted. The results indicate that when the signal-to-noise ratio is fixed, enlarging the dead zone will reduce the standard deviation of the measurement error, while the presence of the dead zone will increase the standard deviation of the measurement error when the incident optical power is fixed. This error model quantitatively reflects the influence of dead zone width on the standard deviation of measurement error of QD under noise interference, providing theoretical reference for improving the tracking accuracy of laser seeker.

For the eddy current testing of bolts and nuts of reactor pressure vessels in nuclear power plants, analyzed the classification and formation mechanism of noise in the inspection process, researched the method of reducing signal noise, and improved the signal quality by improving the process of eddy current probes and software filtering processing, which effectively enhanced the detection rate of defects.

This paper systematically analyzes the current state and development trends in the field of quantum precision measurement through bibliometric methods. Quantum precision measurement technologies, which utilize the principles of quantum mechanics to surpass the limits of classical measurement, play a crucial role in basic physical research, the enhancement of sensing technologies, and the development of new precision instruments. This study employs tools such as VOSviewer and CiteSpace for a quantitative analysis of relevant literature from the Web of Science Core Collection, examining major authors, institutions, journals, and keywords, and creates visual maps of the data.The research identifies quantum entanglement and measurement limits as the core research themes in the field, with quantum entanglement playing a key role in enhancing measurement accuracy and sensitivity. Additionally, the paper identifies key researchers and leading journals in the field, revealing the research achievements and influence of different countries. Through the analysis of citation bursts keywords, this paper further explores the hotspots and future trends in quantum precision measurement.Finally, the paper summarizes the current research status in the field of quantum precision measurement, identifies gaps in the research, and proposes potential future research directions, aiming to provide reference and guidance for further development in this field.

Composite materials have been applied widely because of their special advantages,but due to their anisotropic microstructure,such materials in heat transfer has a macro-anisotropy. The thermodynamic behavior of materials depends on their thermal conductivity to a great extent. So it’s very helpful to reveal the thermal conductivity of materials accurately. For the measurement of thermal conductivity, it can be divided into steady-state method and non-steady-state method according to the different testing principle. At present, the four main measurement methods used for thermal conductivity are plane thermal conductivity method, transient plane source method, transient hot wire method, and laser method. This article introduces and compares the advantages, disadvantages, and applicable scenarios of these four methods from the aspects of working principle, experimental equipment, and measurement accuracy.

In the field of microscopic imaging, such as gene detection of cancer cells and fluorescence microscopic imaging, wider spectral coverage, high numerical aperture and precise chromatic aberration correction are required for microscopic objectives. In this paper, optical software ZEMAX is used to design a flat-field apochromatic microscopic objective with a magnification of 40× and a numerical aperture of 0.8. The objective lens has the characteristics of wide spectral coverage, high numerical aperture and strict color correction. The results of design and analysis show that the flat field number of the objective is 1.15um and the maximum focal shift is less than 0.5um, which conforms to the international standard of microscopic objective. The modulation transfer function (MTF) approaches the diffraction limit at the frequency up to 208lp/mm, and the objective achieves a flat-field apochromatic design in the range of 400-1000nm. The tolerance analysis results show that the MTF value at 208lp/mm has an 80% probability of being better than 0.5974, and machining and assembly can be carried out according to this tolerance allocation.

Laser technology is widely used in medicine, engineering, manufacturing and other fields, including laser therapy for cancer, laser printers, laser radar, and aesthetics. Currently, the issues of human errors and noise in experiments with this technology are challenging to resolve. This paper is to delve into the fundamental principles and practical applications of ultrafast laser pump-probe detection technology. This innovative technique involves utilizing ultrafast laser pulses to stimulate a material, followed by employing a probe light with adjustable delay to gauge changes in transmittance or reflectivity. It also involves constituting the pump-probe detection approach. Initially employed to explore electronic transitions within bands of metals and semiconductors, this technology has evolved rapidly and found widespread utility in investigating intricate oxides and electronic system materials like conventional superconductors, high-temperature superconductors, topological insulators, and multiferroic materials. It has demonstrated distinct advantages in studying spin dynamics and complex multi-body phenomena. Capable of capturing processes at the femtosecond scale, the ultrafast pump detection system holds significant relevance across physics, biology, chemistry, and medicine. This study scrutinized the principles underpinning ultrafast laser pump-probe detection technology and established a comprehensive measurement system using LabVIEW in tandem with other ouipment, enabling automated data acquisition and real-time visualization and streamlining the experimental workload. Furthermore, the integration of optical choppers and lock-in amplifiers effectively mitigated noise interference during the experiment.

As one of the facilities adjacent to the track, the bolts on the high-speed railway sound barrier are an important structure to ensure the safe operation of the railway. However, the traditional manual inspection method has shortcomings, so the automated and intelligent bolt inspection method has become a hot spot in research and development. In this paper, a wireless acceleration sensing system (WASS) based on a MEMS accelerometer is established, and the vibration response change under bolt loosening is analyzed so as to propose a new bolt inspection method. The experimental results show that the top of the sound barrier column is the best detection position. In the vibration acceleration spectrum obtained by WASS, the position changes of the three characteristic peaks can reflect different bolt loosening. The WASS developed has the characteristics of intelligence and remote availability, which will solve the problems existing in the bolt inspection technology of high-speed railway sound barriers and become a strong guarantee for safety maintenance.

No report has been made on the properties of radiation dose rate detection using GAGG: Ce scintillator radioluminescence (RL). This report reveals for the first time the properties of GAGG: Ce scintillators combined with photomultiplier tubes (PMTs) as detectors using optical fibers. We have thoroughly investigated the detection performance of two different sizes of GAGG: Ce scintillators. The experimental results show that the combination of the RL signal of the GAGG: Ce scintillator with the PMT signal can be used to accurately measure the dose rate during irradiation. At a constant dose rate of 10 μsv/h, the stability of the count rate during irradiation was kept within 5%. Meanwhile, the deviation of the count rate was also controlled within 5% at different radiation dose rates. The detector exhibits excellent linear response (R2=0.9910 and R2=0.9807) over the dose rate range of 20 μsv/h to 100 μsv/h. This radiation detector based on GAGG: Ce scintillator and optical fiber transmission is expected to be valuable for a wide range of applications in the fields of radiation monitoring, safety and security, and medical diagnostics, thanks to its compact design, high stability detection capability and real-time measurement function.

Aiming at the problem that when combining confocal microscopy and resonance Raman spectroscopy (RRS), the focusing accuracy of the system decreases due to the shift of the focusing plane of the beam caused by the change of the work wavelength, a laser dual-wavelength differential confocal sensing technology (DDCST) with virtual pinhole and CCD detection is proposed, the basic theory based on the wavelength and focusing plane position relationship has been established, which can provide a precise theoretical basis for the determination of the focusing accuracy of the Confocal microscopy (CM)-RRS, and greatly improve the system accuracy, and uses a CCD as detector. DDCST sets a microregion on the CCD imaging plane as a virtual pinhole, can freely adjust the position and size of the pinhole in the software to match with the sample reflectivity and detector response range in measurements. So, DDCST significantly simplifies the detection system and pinhole adjustment, eliminates the error attributed to the adjustment error of the physical pinhole. Theoretical analyses and preliminary experiments indicate that DDCST has an axial resolution of about 5nm and 6nm respectively, and a lateral resolution of about 1µm and 1.2µm respectively when the work wavelength is 532nm and 653nm respectively, can recognizes the influence of the change of the work wavelength on the focusing accuracy of the system, which can lay the foundation of the morphology imaging of the probing micro-region, and provide theoretical support and help for the development of the CM-RRS.

This paper introduces an innovative active terahertz (THz) modulator that employs dynamic graphene-silicon nanoarrays (DGSN) to address the challenges of dynamically manipulating THz waves. The DGSN combines the exceptional electrical properties of graphene with the enhanced optical absorption capabilities of silicon nanoarrays, thereby enabling dual-mode active control via optical pumping and electrical biasing. An 808 nm laser is used to photoexcitation carriers in the silicon nanoarrays for optical pumping, while a bias voltage modulates the Fermi level of graphene, subsequently altering its conductivity and influencing the transmission properties of THz waves. Simulations reveal modulation depths of up to 59% and 99% under optical pumping and dual-mode control, respectively. This study provides theoretical insights into the modulation mechanisms and lays a solid foundation for the design and optimization of high-performance THz modulation devices, showcasing the immense potential of the DGSN in advancing THz technology.

In view of the scale graphite purification in the process of process conditions and equipment complex, high cost, and environmental pollution, this paper through the basic principle of scale graphite purification and the characteristics of lowtemperature plasma, according to a new graphite purification technology, designs a graphite purification device with a simple structure, which is easy to operate. The purification process has no waste gas, waste liquid emissions, and no pollution to the environment, which conforms to the development of green environmental protection concept, solves the issues that traditional graphite purification method purification equipment cannot continuously operate, and has long purification cycle, high cost, and serious pollution. According to the graphite carbon content test of the purified products, it is known that the graphite purification device in this paper can purify the graphite with 92% carbon content to the graphite with a carbon content of more than 99%.

With the escalating demand for oil and gas resources, the safety of subterranean casings and other petroleum extraction infrastructure is increasingly under scrutiny. Traditional electromagnetic flaw detection methods assess the corrosion or damage to both the inner and outer layers of casings through calculations of wall thickness. In this study, MMS360 magnetic scanning technology is explored, building upon conventional electromagnetic flaw detection approaches. The research introduces an innovative symmetric layout for similar-pole magnetic field coils, leading to the development of a radial magnetic scanning system. Field tests have effectively confirmed the reliability and precision of the MMS360 magnetic scanning technology.

With the increasing demand for visibility observations in fields such as wind power generation, meteorological observation, and civil aviation safety, the development of laser lidar for visibility monitoring based on the principle of backscattering has been realized. This paper uses the raw signal data obtained from the laser lidar as the basic data source, and, based on signal preprocessing, constructs a visibility retrieval model to achieve accurate extraction of visibility information. The laser lidar integrated with this visibility extraction method was tested in typical regions. The test results indicate that the visibility extraction method based on laser lidar achieved good results, showing a distribution consistent with the visibility measurement results of traditional visibility instruments, presenting a linear correlation with a correlation coefficient above 0.96, thereby enhancing the reliability of visibility products retrieved using laser lidar.

Light column sphygmomanometer uses light column instead of mercury as the indicator of sphygmomanometer, which is clear and intuitive, easy to use, earthquake resistant, impact resistant, reliable and durable. However, because LED light column sphygmomanometer has no pointer or mechanical transmission indication, and the seal of the pressure sensor chamber is not connected to the atmosphere, the national verification regulation JJG 270-2008 sphygmomanometer is not applicable to it. Until now there is no relevant national verification regulation or calibration specification. This article analyzes and determines the key measurement parameters of light column sphygmomanometer and presents their corresponding calibration method, as well as analyzes the experimental results and carries out uncertainty evaluation of calibration results, according to the relevant characteristics of the light column sphygmomanometer, and with reference to JJG 270-2008 sphygmomanometer. The experimental results prove that the calibration method is operable for the calibration of light column sphygmomanometer, including its appearance, zero position error, pressure indication error, and air tightness, which provides the basis for the effective traceability of light column sphygmomanometer.

In this paper, in order to compare the noise-resistant ability of Frenet framework and Bishop framework in multi-core fiber shape sensing technology, and to study the effect of different filtering methods on the improvement of the shape reconstruction accuracy of the two frameworks, the study verifies the feasibility, accuracy and noise-resistant ability of the shape sensing based on the two frameworks respectively by taking the cylindrical helix curve as an example, and investigates the effect of the reconstruction error of the Frenet framework and the Bishop framework based on the different filtering methods respectively. and Bishop framework on the reconstruction error, respectively. The results show that under the ideal state of no noise, both Frenet and Bishop frames can achieve reconstruction errors no higher than 0.13%, while the former's noise immunity is obviously inferior to the latter's. The results show that the Frenet and Bishop frames can achieve reconstruction errors no higher than 0.13% under the ideal state of no noise. Meanwhile, low-pass filtering can most significantly improve the reconstruction accuracy of the Frenet framework, while for the Bishop framework, median filtering is the most effective. The results of this paper provide theoretical support for the optimization of multi-core fiber shape sensing technology, and provide a reference for the selection of frames and the application of filtering methods in different application scenarios.

All-fiber photoacoustic sensing, characterized by its compact size and ease of integration, has significant potential in applications such as non-destructive testing and structural health monitoring. Traditional calibration of photoacoustic transducers relies on high-frequency hydrophones, which are limited to liquid environments, posing challenges for realtime calibration in air. This study introduces a novel method for photoacoustic pressure calibration based on fiber Bragg gratings (FBGs), which are well-known for their high sensitivity and wavelength division multiplexing capabilities. We establish a theoretical model linking photoacoustic pressure, FBG reflection spectra, and photodetector responsivity. By constructing an FBG-based photoacoustic pressure calibration system, we validate its performance against a standard highfrequency hydrophone (PA FOHS, England), achieving a calibration error of just 0.6%. Unlike conventional hydrophonebased methods, this approach allows for calibration in non-liquid environments, expanding its applicability. We anticipate that this method will advance the use of all-fiber photoacoustic technology in various fields, including non-destructive testing and structural health monitoring.

The transmission and protection of confidential information play an extremely important role in the field of information security. In the military field, optical anti-counterfeiting technology is widely used in aviation equipment, military communication, military reconnaissance, and so on. At present, simple optical anti-counterfeiting no longer meets current anti-counterfeiting needs. Therefore, it’s necessary to develop multimodal, stable and low toxicity luminescent materials to meet higher levels of anti-counterfeiting needs. In this paper, Cu⁺ and Sb³⁺ were co-doped to Cs2ZnCl4 single crystals, which exhibited white and red emission under 254- and 365-nm UV excitation, respectively. Based on the multi exciton emission characteristics of Cu⁺ and Sb³⁺ co-doped Cs₂ZnCl₄ single crystals, a digital encrypted information transmission system was designed, achieving dual anti-counterfeiting. This provides a feasible solution for the development of new metal halides for optical anti-counterfeiting applications

Existing micro-imaging systems are primarily designed for specific types of magnets and are not compatible with watercooled magnets, posing significant limitations in their use. In light of this, the article proposes a solution: a micro-imaging sample rod suitable for water-cooled magnets, designed for easy installation and removal. The microscopic imaging sample rod consists of an upper optical path box and a lower rod body. The optical path is integrated within the optical path box, divided into five layers, each securely fixed inside the box. The upper and lower parts of the optical path box can connect freely. The optical components inside the optical path box are installed very compactly, enabling miniaturization of the optical path box. Simulation and modeling of the sample rod have yielded excellent results.

X-ray focusing mirrors are of significant value in the field of optical inspection. Their imaging quality requires highprecision reflective surface. This paper proposes a method for calculating dwell time based on the Alternating Direction Method of Multipliers (ADMM) in Computer Controlled Optical Surfacing (CCOS), suitable for correcting surface error of cylindrical mold used in X-ray focusing mirrors. Through mathematical modeling, and material removal model derivation, a dwell time calculation model based on linear equations is established and solved using the ADMM algorithm. Simulation results demonstrate that this method outperforms the traditional Least Squares QR Decomposition (LSQR) algorithm in terms of surface precision, convergence rate, and algorithmic efficiency.

Currently, synchronous phase-shifting interferometry often requires specific optical components or introduces additional phase due to different optical elements in the paths of object and reference beams. To address this issue, we proposed a synchronous phase-shifting interferometer. This interferometer is adapted from a Mach-Zehnder interferometer and can simultaneously capture two phase-shifting holograms. Based on the existing algorithm of phase retrieval, we conducted the theoretical derivation, simulated and experimental work to confirm the feasibility of our system preliminarily.

Fiber optic MEMS Fiber -Perot sensors have gradually become a popular research topic. However, when the sensor's spectrum is distorted, there is limited research on high-precision peak detection algorithms used in demodulation. In response to this research gap, this paper proposes an adaptive peak detection algorithm to address the issue of spectral distortion. Firstly, we segment the interference spectrum demodulated by the interrogator using the Hilbert transform method to obtain multiple independent interference spectra with only one peak. For each dataset obtained through Hilbert transformation, the number of data points on both sides is detected with its peak as the center. If the number of data points on both sides is equivalent, it proves that the interference spectrum has not been distorted. Otherwise, the interference spectrum has been distorted. We propose a spectral correction algorithm based on Gaussian fitting for distorted spectra which detailed information is reported below, and achieve the accurate peak of distorted spectra by this method. We have carried out experiments in the laboratory, and the results showed that the algorithm error was less than 0.0051MPa within the pressure range of 0-3MPa.

Decorrelation-based optical coherence tomography angiography (OCTA) is a widely utilized technique that leverages OCT intensity data for imaging. Nevertheless, the quality of these images is often compromised by the cardiac and respiratory motions in animals. These cyclical bulk motions, particularly in the C-Scan (slow scan) direction, obstruct motion correction by altering the scan position and the OCT structure. While various correction methods have been proposed, they frequently result in the loss of vascular information under substantial bulk motion conditions. In this study, we present a novel correction method employing a stitch scan protocol in the C-Scan direction. By setting a threshold for the maximum value of normalized cross-correlation among repeated B-Scan intensity signals, we effectively exclude false OCT B-scans. In vivo imaging experiments on mice demonstrate that our bulk method preserves the complete vascular information and significantly improves image quality.

A mask optimization method based on the diffusion model to establish a network framework through integration with a traditional ILT solver in order to mitigate the influence of the optical proximity effect (OPE). Meanwhile, the method can greatly accelerate the optimization process when the input mask pattern is huge and complex. The method initially divides the masks into different classes and learns their features separately using a diffusion model optimized with a specific probability transfer matrix. Subsequently, the learned coarsened masks are computed by the ILT solver to obtain the optimized masks. The simulation results indicate that this method can greatly accelerate the mask optimization process when faced with a large and complex input mask pattern.

Ultrasonic decontamination technology was used to carry out decontamination tests on stainless steel pipes, observe the decontamination effect of ultrasonic decontamination on pipelines, and explore the influence of ultrasonic decontamination on the safety of pipelines containing welds. Metallic film was used to characterize the decontamination effect, metallographic microscope, micro-Vickers hardness tester, universal testing machine and other equipment were used to observe the matrix structure of the pipeline, compare the hardness and strength changes, and analyze the influence of ultrasonic decontamination on the safety of the pipeline. The experiment shows that with the determination of power, the ultrasonic decontamination effect is gradually enhanced with the extension of ultrasonic decontamination time. The mechanical properties test shows that the effect of ultrasonic decontamination on the material damage of pipeline matrix is almost zero under appropriate parameters.

The study of biomolecular interactions is critical for understanding various biological processes. Atomic force microscopy (AFM) has now become a common method for studying biomolecular interactions. Such experiments typically generate large amounts of force curves, and manually analyzing these data is extremely time-consuming and prone to subjective biases. Many algorithms have been proposed for the automatic processing of force curves. However, existing algorithms primarily focus on searching events in curves, and have limited functionality in differentiating between specific and nonspecific interactions. To address this problem, this study proposes FSASIS (Force Spectroscopy Analysis for Specific Interaction Selection), a new algorithm for processing and analyzing force spectroscopy data. FSASIS can detects all events in force curves and subsequently identifies specific unbinding events among them. We use FSASIS to analyze the measured force curve, the results demonstrate that FSASIS can analyze force curves with high accuracy, and significantly improves the efficiency of experiments.

In the manufacturing process of a specific type of conical cylinder, high-frequency argon arc welding is employed for butt welding. The uncertainty of the butt weld position relative to the welding gun results in excessive manual labor during production, leading to suboptimal product qualification rates; Consequently, the implementation of a fusion laser welding seam tracking automated control system was initiated. This system utilizes a PLC to gather various sensor data signals, control servomotors, valves, and motors, thereby establishing a comprehensive automated butt welding tracking control system. Ultimately, this achieves the goals of reducing labor costs, diminishing labor intensity, and enhancing both production efficiency and product quality.

With the wide application of laser semi-active guided weapons, the research on jamming technology for laser guided weapons has become a hot spot of research at home and abroad day by day. Among them, laser high-frequency jamming has the advantages of simple implementation and good jamming effect, which makes it a very effective jamming method. Commonly used anti-high-frequency methods are coded wavegate technology, reverse suppression gate technology, are based on the pulse width spreading signal judgment, but in the interference frequency is high, the signal receiving system can not be completely stripped of the interference signal, and thus can not be effective anti-high-frequency interference.By analyzing the mechanism of laser high-frequency active interference, a high-speed sampling-based laser semi-active guide head anti-high-frequency interference method is now proposed, which uses a high-speed sampling chip to sample the characteristics of the measurement signal, combined with a feature recognition algorithm to identify the high-frequency interference to be rejected. After laboratory and outdoor verification, the method can effectively reject 200kHz highfrequency interference signal and achieve the purpose of precise guidance.