ArticleList

Application of optical carrier suppression modulation technology in the calibration of frequency shift for Brillouin optical time domain reflectometers

Xiaoqiang SUN, Dongbo FU, Xuanyu ZHOU, Wenhui HAO, Longquan CHEN, and Dayuan ZHANG

A Brillouin frequency shift parameter calibration method based on optical carrier suppression modulation technology is proposed to meet the metrological calibration requirements for frequency shift of Brillouin optical time domain reflectometer (BOTDR) in distributed fiber sensors. Fiber Brillouin scattering signals were simulated using the frequency doubling signal generated by optical carrier suppression modulation technology, and a mathematical model and value traceability diagram between the Brillouin frequency shift reference value and the output signal frequency of the signal generator were provided, to achieve the value traceability of Brillouin frequency shift to the atomic time standard reference device. By adjusting the frequency of the output signal of the signal generator, the Brillouin frequency shift indication error at different frequency points within the frequency shift range can be obtained. Experiments were conducted to obtain calibration results for different frequency shift points within the range of 10.6 to 11.8 GHz, and an uncertainty analysis was performed. When the measured Brillouin frequency shift value is 10 998.38 MHz, the expanded uncertainty is 0.07 MHz (k = 2). This calibration method can meet the metrological traceability requirements for BOTDR frequency shift in the field of fiber optic sensing applications, providing strong support for promoting the performance improvement and widespread application of BOTDR.

Nov. 21, 2025
Metrology & Measurement Technology
Vol. 45, Issue 5, 90 (2025)
DOI：10.11823/j.issn.1674-5795.2025.05.09

Thin film strain sensor manufactured by integrated forming on hydraulic pipeline

Guoxi LUO, Yuzhuo ZHANG, Zeng JIA, Wenyan LI, and Libo ZHAO

Traditional strain gauges face challenges such as significant strain transfer errors and slow response during monitoring, severely limiting the engineering effectiveness. To addresses the monitoring requirements for strain, vibration, and clamp looseness in aviation hydraulic pipelines, this paper proposed a design and manufacturing method for in?situ preparation of thin?film strain sensors on hydraulic pipelines. A finite element analysis model for strain transfer errors was established, and the structural parameters of the resistive strain grating were optimized. Multi?layer hetero?thin films, including the Ni80Cr20 strain?sensitive layer, were prepared using magnetron sputtering technology. Through a five?axis laser etching process, the laser incidence angle and focal position were adjusted in real?time, achieving a high?precision control over the etching depth. Testing revealed that the prepared thin?film strain sensor exhibited a drift rate (DR) of 8.4 × 10-5 h-1, a temperature coefficient of resistance (TCR) of 1.3 × 10-4 ℃-1 in the range of -40 ~ 100 ℃, a gauge factor (GF) of 2.03 in the strain range of 0 ~ 500 με, and a response time of just 15 ns. Force hammer experiments confirmed the sensor's ability to detect and identify key information such as strain, vibration, and clamp tightness. This integrated manufacturing sensor holds promising applications in the field of aviation hydraulic pipeline condition monitoring.

Nov. 21, 2025
Metrology & Measurement Technology
Vol. 45, Issue 5, 79 (2025)
DOI：10.11823/j.issn.1674-5795.2025.05.08

Cluster phenomenon in generalized Grover's quantum walks

Weiwei ZHANG, Zuowei CHEN, Wei ZHAO, Beiya YANG, Hengyue JIA, Wei PAN, and Haobin SHI

To explore the application of quantum walks in metrology, generalized Grover quantum walks and stepwise Grover quantum walks with arbitrary control parameters are proposed. The correlation between the corresponding clustering phenomena and the model's adjustable parameters were studied. The role of control parameters in the evolution of quantum walks was analyzed, revealing a clustering phenomenon based on control parameters: the evolution speed of the walker shows consistency with the entanglement between its coin space and position space. Further investigation into the probability distribution of the walker in different clusters shows that the probability distributions in each cluster exhibit different characteristics. In some clusters, the distribution tends to be concentrated, while in others, it is more dispersed. The experimental implementation of Grover quantum walks is discussed, and the applications of Grover quantum walks in metrology are addressed, highlighting their significance in achieving high?precision sensing, topological order measurement, and enhanced state tomography efficiency. The research findings provide strong support for the development of quantum walk?based information processing technologies.

Nov. 21, 2025
Metrology & Measurement Technology
Vol. 45, Issue 5, 68 (2025)
DOI：10.11823/j.issn.1674-5795.2025.05.07

Summary of research on status monitoring technology of mechanical equipment operation based on digital twins

Yuxuan LIU, Caiguohui GUO, Chong YU, Chengcheng LI, and Luowen Wang

With the rapid development of industry and manufacturing in China, the traditional maintenance methods of mechanical equipment gradually can't meet the requirements of high?efficiency production, and the demand for real?time monitoring of mechanical equipment operation status is constantly rising. In recent years, the development and application of digital twin technology provide a new idea for the monitoring of mechanical equipment operation status. This paper describes the importance of mechanical equipment operation status monitoring and the basic concept of digital twins, focuses on the analysis of the relevant theory of information fusion in the field of digital twins, combs the multi?information fusion status monitoring technology, summarizes the advantages and disadvantages of each theory, and makes a comparative analysis. Finally, according to the research status of information fusion theory, the prospect is made from the application goal?oriented construction of digital twin model, the exploration of intelligent model real?time update technology, and the construction of sensor digital twin model, which provides a reference for the research and development of digital twin driven mechanical equipment operation status monitoring technology in the future.

Nov. 21, 2025
Metrology & Measurement Technology
Vol. 45, Issue 5, 48 (2025)
DOI：10.11823/j.issn.1674-5795.2025.05.06

Accurate measurement method for geometric features of short circular arcs with large radii

Fuqiang LI, Peng CHEN, Jiqing XIE, Yongdang CHEN, and Zhiyong CHANG

Aiming at the problem that the efficiency and accuracy of existing measurement methods for geometric features of large?radius short arcs are difficult to meet the inspection requirements of mass?produced parts, a new measurement method is proposed. Firstly, a coordinate measuring machine is used to measure the two straight edges connected to the arc, and the intersection coordinates and included angle of the two straight lines are calculated. Then, the direction vector of the angle bisector is solved. The coordinate measuring machine is used to approach the workpiece along the direction vector from the intersection of the two straight lines, and the contact point between the coordinate measuring machine probe and the arc is recorded. The distance between the contact point and the intersection of the two straight lines is calculated, and finally the arc radius is obtained based on this distance. Experiments were conducted to verify the application effect of the proposed method, and the results show that compared with traditional measurement methods, this method has higher measurement accuracy and shorter time consumption. The research results are of great significance for promoting technological progress in the field of high?end manufacturing.

Nov. 21, 2025
Metrology & Measurement Technology
Vol. 45, Issue 5, 40 (2025)
DOI：10.11823/j.issn.1674-5795.2025.05.05

Reliability assignment method for shore unloading operations based on IWOA

Jinlong SHI, Lingling FENG, Lei ZHANG, and Yinsheng CHEN

Aiming at the problem that the research on the reliability assignment method of the shore?landing unloading system is not perfect and the reliability assignment results need to be optimized, a reliability assignment method based on the improved whale optimization algorithm (IWOA) was proposed. According to the parallel and series logical relationships existing among various tasks of the shoreline unloading system, a reliability assignment model of the unloading system was constructed, and reliability allocation method based on the IWOA was designed to complete the relia?bility allocation of tasks. The simulation method was used to evaluate the assignment results of the proposed method, and the reliability assignment method for shore unloading operation was verified. The simulation results show that the optimal reliability of the system is 0.975, which can enhance the task reliability allocation capability of the shore unloading operation system.

Nov. 21, 2025
Metrology & Measurement Technology
Vol. 45, Issue 5, 30 (2025)
DOI：10.11823/j.issn.1674-5795.2025.05.04

Design and implementation of six⁃module antenna based on wireless telemetry system

Zhengwei HUANG, Piqiang SU, Jie GUO, Xizhi SU, and Jing DONG

To meet the requirements of multi?point and multi?parameter signal transmission in the limited installation space of the rotating parts test equipment for aeroengines, a six?module antenna based on a wireless telemetry system was developed. The design of the transmitting and receiving modules was made based on microstrip antenna technique to achieve the miniaturization of the device. The antenna model after packaging was established in the simulation software, and the influences of the thickness of the packaging glue, the dielectric constant of the material, and the tangent of the loss angle on the reflection coefficient (S11) and transmission coefficient (S21) of the antenna feeding port were analyzed. According to the simulation results, the design parameters were optimized, and the six?module antenna was developed and its performance was tested. The results show that the working frequency range of the antenna is 1.3 ~ 1.7 GHz, and the working bandwidth is not less than 40 MHz, which meets the signal transmission design requirements. Low?speed rotation tests were conducted under the conditions that the installation distances between the rotor and stator antennas were 8 mm and 10 mm, respectively, and high?speed rotation tests were conducted under the conditions of a rotational speed of 20 000 r / min and an ambient temperature of 80 ℃. The data packet loss rate of the system was less than 1% in both cases. The developed six?module antenna can reliably and efficiently transmit data from 60 measurement points and multiple types of data, providing strong support for the performance testing of rotating components such as compressors and turbines in aeroengines.

Nov. 21, 2025
Metrology & Measurement Technology
Vol. 45, Issue 5, 19 (2025)
DOI：10.11823/j.issn.1674-5795.2025.05.03

Mixed filtering method based on adaptive parameters for inhomogeneous 3D point clouds

Qian CHENG, Can HAO, Yang LI, Chao GAO, Tong LIU, and Dengfeng DONG

The diversity of materials and complex geometric shapes of the intelligent manufactured components lead to sparse 3D point clouds at edge regions, resulting in non?uniform density distribution across complex mechanical parts. This study proposes a hybrid filtering method integrating density?adaptive SOR and ROR to remove multiple noise types of complex component point clouds. The method firstly merges voxels of the segmented point clouds based on density similarity, then establishes minimum neighborhood points for ROR using merged voxel size exponents, afterward determines search radius through neighborhood average distances, and calculates SOR standard deviations using scaling coefficients. The proposed method was tested using classical 3D point cloud models. Experiment results demonstrates that the edge retention of post?processed point clouds significantly exceed those achieved by fixed?parameter filtering methods, while effectively preserving detail information in sparse regions, and the noise removal rate is also improved. Robustness tests conducted under varying noise levels confirm the consistent performance across different noise intensities. This method establishes a technical foundation for online inspection in intelligent manufacturing systems requiring high?fidelity geometric reconstruction.

Nov. 21, 2025
Metrology & Measurement Technology
Vol. 45, Issue 5, 10 (2025)
DOI：10.11823/j.issn.1674-5795.2025.05.02

Pressure sensor chip fabrication and optimization for traction and braking systems in high⁃speed trains with speeds of 350 km / h and above

Dezhi ZHENG, Xiaoyuan DONG, Aobei CHEN, Ying SUN, Chun HU, and Shuai WANG

To meet the stringent requirements for high accuracy, wide dynamic range, and rapid response of pressure sensors under the complex operating conditions of high?speed train traction and braking systems, this study presents the design, fabrication, and multiphysics optimization of a high?performance piezoresistive pressure sensor chip. By emplo?ying multiphysics coupling modeling theory in combination with a structural parameter optimization approach, this study systematically investigates the synergistic influence of diaphragm thickness, piezoresistor layout, and doping concentration on sensor performance, and proposes a parameterization?based stiffness?sensitivity co?optimization strategy for the diaphragm. Furthermore, by developing an eight?mask photolithography process and a composite wet etching technique based on KOH / IPA, a submicron?level control accuracy of diaphragm thickness was achieved. Finite element simulation results demonstrate a sensitivity of 56.987 mV / kPa, a nonlinearity of 0.048% FS, and structural stability under 300% overpressure. This work addresses a key technological bottleneck in high?accuracy pressure sensor fabrication and lays the foundation for fully localized production of safety?critical sensing components in next?generation traction systems for high?speed train.

Nov. 21, 2025
Metrology & Measurement Technology
Vol. 45, Issue 5, 108 (2025)
DOI：10.11823/j.issn.1674-5795.2025.05.11

Deep learning⁃based multi⁃channel MOS environmental gas detection system

Chenyang ZHANG, Guangshun LIU, Pengfei MA, and Yinsheng CHEN

To address the need for multi?component gas detection in complex environments, this paper presents the design and implementation of a portable multi?channel gas detection system based on metal?oxide semiconductor (MOS) sensors. The system integrates an eight?channel sensor array, a high?precision signal?acquisition circuit, and a low?power hardware. A multi?branch convolutional neural network combined with a bidirectional long short?term memory network is employed to achieve automatic feature extraction and temporal modeling of multi?channel signals. Experiments using CO, C2H5OH, and their interfering gases and mixtures as the research subjects demonstrate that the system exhibits linear responses and high detection accuracy across different ranges of concentration. Comparative tests validate that the sensor?fusion strategy improves classification accuracy, enhances robustness, and increases adaptability to complex environments, with the classification accuracy for mixed gases reaching up to 100%. This study provides a reliable technical basis and practical reference for multi?component gas detection in environmental monitoring, industrial safety, and public health applications.

Nov. 21, 2025
Metrology & Measurement Technology
Vol. 45, Issue 5, 97 (2025)
DOI：10.11823/j.issn.1674-5795.2025.05.10

Revisiting discussion on inherent characteristics of quantization error in digital⁃to⁃analogue conversion

Zuliang LU, Yan YANG and Zhonghua ZHANG

To accurately achieve the desired phase angle during digital?to?analog conversion, a commonly used approach is to increase the conversion resolution. This method relies on finer amplitude?axis discretization to better approximate the original waveform. However, it comes with several disadvantages, such as high cost, slow conversion speed, and considerable power consumption. To solve these problems, this paper further explores a novel method — time?axis segmentation. A definition of quantization error is introduced, which includes both phase angle quantization error (PQE) and amplitude quantization error (AQE). Four essential conditions for the quantization process are presented. The paper also analyzes how the quantization error inherently varies with the phase angle. Simulation and experimental results are provided to validate the theoretical conclusions. The results show that the quantization errors exhibit a periodic distribution, with the error period being 1 / N of the signal cycle, where N denotes the number of samples per signal cycle. Within each error period, the quantization errors are symmetrically distributed. Moreover, a series of zero?points of the phase angle quantization error is derived, which are independent of both the conversion resolution and the signal amplitude. By adjusting N to link these zero?points with the desired phase angle, new application opportunities arise, which is expected to contribute to the advancement of phase angle standards and impedance bridge technology, and promote the use of high?speed, low?power, and cost?effective digital?to?analog converters.

Nov. 21, 2025
Metrology & Measurement Technology
Vol. 45, Issue 5, 1 (2025)
DOI：10.11823/j.issn.1674-5795.2025.05.01

Dynamic weighted method for defect detection and evaluation in bamboo and wood materials based on improved YOLO

Peixuan ZHANG, Yiwei DONG, Yi ZHANG, Ruiyang YIN, Xianxing WU, and Shouzheng LI

To address the unstable quality of processed bamboo and wood products caused by both the performance limitations of current processing machinery and the inherent defects of bamboo and wood materials, this study focuses on key defect detection technologies within intelligent wood manufacturing, and proposes an integrated quality assessment system based on an improved YOLO （You Only Look Once）object detection algorithm. Innovatively, the system incorporates a multi⁃parameter defect weighting mechanism, enabling quantitative analysis of critical indicators such as defect size, characteristics, and severity. Subsequently, a wood quality grading model was constructed using fuzzy comprehensive evaluation. Experimental results demonstrate that the system effectively categorizes wood products into three grades: superior (Grade A), qualified (Grade B), and unqualified (Grade C). For the Plywood wood defect dataset, the system achieved mean average precision@0.5 （mAP@0.5） of 91.3%. Moreover, the dynamic weighting⁃based grading strategy showed a deviation of less than 5% compared to manual evaluation results (Euclidean distance: 0.063; Jaccard index: 0.892). This research provides an efficient and scalable quality assessment paradigm for intelligent wood manufacturing, demonstrating significant engineering application value.

Oct. 09, 2025
Metrology & Measurement Technology
Vol. 45, Issue 4, 74 (2025)
DOI：10.11823/j.issn.1674-5795.2025.04.06

Advances in high⁃temperature gas sensing techniques using laser dispersion spectroscopy

Chen ZHOU, Shuang GUO and Liuhao MA

LDS is an advanced laser?based spectroscopic technique for gas sensing with a broad dynamic range and high immunity to optical power fluctuations. It has attracted considerable attention in trace gas detection and combustion diagnostics. Starting from the motivation for conducting research on LDS technology, this review systematically introduces the fundamental spectroscopic principles of LDS and establishes a theoretical analysis framework. It highlights the key features and implementation methods of HPSDS and CLaDS, and explores approaches for constructing calibration?free models. By examining the representative LDS applications in the past decade in typical scenarios such as combustion diagnostics, high?temperature flue gas monitoring, and environmental optical trace gas detection, this review elucidates the distinct technical requirements of these application domains. Finally, regarding such challenges as the insufficient detection sensitivity and complex system configurations, the paper indicates the future development directions from both fundamental research and practical application perspectives, providing a systematic reference for advancing the theoretical foundations and engineering applications of LDS.

Oct. 09, 2025
Metrology & Measurement Technology
Vol. 45, Issue 4, 119 (2025)
DOI：10.11823/j.issn.1674-5795.2025.04.09

Review on the frequency domain analysis of blade tip timing measurement for rotor blade vibration

Zengkun WANG, Zhibo YANG, Baijie QIAO, Shuming WU, Jiahui CAO, and Xuefeng CHEN

The principle of blade tip timing technology is introduced. The current state of research on the under?sampled signal analysis in the frequency domain for blade tip timing is reviewed. The applications of four sensor placement strategies in the frequency domain analysis of blade tip timing are discussed, including a single sensor, dual sensors, sensors with specific location constraints, and multiple sensors. Four approaches for the frequency spectrum analysis of undersampled signals are presented, which are time series fitting, band?limited signal reconstruction theory, sparse representation theory, and array signal processing, with an emphasis on their theoretical foundations as well as their strengths and limitations. The characteristics of the synchronous and asynchronous vibration analysis in the field of blade tip timing are discussed. Furthermore, four future research directions for frequency domain analysis of blade tip timing technology are identified, including uncertainty analysis of sampling, assessment of amplitude analysis validity, data analysis of novel blade tip sampling strategies, and intelligent feature extraction and fault diagnosis.

Oct. 09, 2025
Metrology & Measurement Technology
Vol. 45, Issue 4, 104 (2025)
DOI：10.11823/j.issn.1674-5795.2025.04.08

Review of the development of aircraft wing deformation measurement technology

Shuang CHEN, Li ZHANG, Penghao ZHANG, Guanghui SUI, Tian WU, Xinying ZHANG, and Hongbo WU

Aircraft wings are inevitably subjected to diverse and intricate loads in the course of flight, which induce the deformation. Precise measurement of the wing deformation holds vital importance for ensuring flight safety, optimizing aircraft performance, and enabling the advancement of aeronautical structure design. This paper presents a comprehensive review of the principal techniques currently utilized in the aircraft wing deformation measurement, both domestically and internationally. These techniques encompass the linear displacement sensor method, strain sensor method, stereoscopic vision measurement method, optical fiber sensing method, and others. A detailed comparative analysis is made, examining the merits and demerits of each method with respect to the measurement accuracy, real?time performance, and environmental adaptability. Additionally, the paper discusses the application status of these techniques in the practical monitoring of aircraft wing deformation. Lastly, this paper anticipates the future development directions for further enhancing the capabilities of wing deformation measurement. The prime objective is to provide a valuable reference for wing health monitoring and performance optimization within the realm of aeronautical engineering.

Oct. 09, 2025
Metrology & Measurement Technology
Vol. 45, Issue 4, 87 (2025)
DOI：10.11823/j.issn.1674-5795.2025.04.07

Monitoring method for wall thickness of variable⁃temperature pipelines based on ultrasonic guided waves

Shuhua PAN, Jianbo WU, Hui XIA, Zhe WANG, Ganghua HUANG, and Yuxuan GONG

Aiming at the problem of the decline in the accuracy of ultrasonic wall thickness measurement caused by temperature fluctuations during the operation of high?temperature petrochemical pipelines, a measurement method based on the inversion of temperature and the compensation of wall thickness by ultrasonic guided wave signals is proposed. A two?dimensional steady?state heat transfer model was established, the temperature field distribution of the waveguide strip was analyzed, an ultrasonic flight time prediction model was constructed, the quantitative relationship between the pipe temperature and the ultrasonic flight time in the waveguide was characterized, and the real?time measurement of the temperature of high?temperature pipes was achieved. On this basis, the ultrasonic guided wave thickness measurement data was compensated to improve the accuracy of pipe wall thickness monitoring. An ultrasonic guided wave measurement platform was built and experiments were performed. The results show that within the range of 15 ~ 500 ℃, this method can achieve precise measurement of the temperature change of the pipeline, and the measurement error of the wall thickness after compensation is ± 0.1 mm. This method breaks through the application bottleneck of the existing guided wave thickness measurement devices in variable?temperature environments, providing technical support for the safe operation of petrochemical plants.

Oct. 09, 2025
Metrology & Measurement Technology
Vol. 45, Issue 4, 66 (2025)
DOI：10.11823/j.issn.1674-5795.2025.04.05

Global optimized calibration method for double⁃specular⁃surface shape measurement system

Wenjing HE, Yubo NI, Xiuxiu TIAN, Ziyu LI, Yanling LI, and Zonghua ZHANG

To achieve high?precision measurement of the complete three?dimensional (3D) shape of double?specular?surface objects, a global optimization method for system calibration is proposed. Firstly, a double?specular?surface shape measurement system is established using two direct phase measuring deflectometry subsystems without overlapping Field?of?View (FoV), which fully covers the measured FoV of the double?specular?surface object. Secondly, traditional methods are applied for depth calibration, lateral calibration of each subsystem, and calibration of the transformation between the measurement references of the two subsystems. Finally, a high?precision double?specular?surface calibrator is employed to optimize the initial calibration parameters. Three measurement errors are introduced to evaluate the 3D measurement accuracy of the calibrator. By minimizing the defined measurement errors, the optimal calibration parameters are calculated. Comparative experiments were performed to verify the application effects of the global optimization system calibration method. When the initial system calibration method was used to obtain the system parameters, and then the complete 3D shape of a gauge block was reconstructed, the root mean square error (RRMSE) of the distance between the two surfaces of the gauge block was 164 μm. When the global optimization system calibration method was employed to determine the system parameters and reconstruct the complete 3D shape of the gauge block, the RRMSE for the distance between the two surfaces was reduced to 34 μm. The global optimization system calibration method effectively improves the 3D shape measurement accuracy of double?specular?surface objects, providing a technical reference for enhancing the calibration precision of multi?sensor optical measurement systems under non?common?view conditions.

Oct. 09, 2025
Metrology & Measurement Technology
Vol. 45, Issue 4, 57 (2025)
DOI：10.11823/j.issn.1674-5795.2025.04.04

High⁃temperature DIC measurement method based on adaptive optimization of degradation function and grayscale average

Chengshuang MAO, Shan GAO, Hailong LIU, and Zixu WANG

To address the challenges of speckle image blurring and noise coupling caused by thermal airflow disturbances in high?temperature environments, a collaborative restoration method that integrates image degradation theory and multi?frame signal processing is proposed. Firstly, by constructing an adaptive loss function optimization model based on the Structural Similarity Index (SSIM), the degradation parameters are adaptively estimated, breaking through the limitations of the mismatch between the traditional fixed degradation model and the actual thermal disturbances. Then, by combining Wiener filtering and grayscale averaging techniques, the joint optimization of deblurring and denoising is achieved, solving the technical problem of balancing noise suppression and detail preservation. The verification results on a 600 °C high?temperature experimental platform show that the root mean square error of image displacement measurement processed by the traditional grayscale averaging method is 0.006 4 mm; the root mean square error of image displacement measurement processed by the high?temperature Digital Image Correlation (DIC) measurement method based on adaptive optimization of the degradation function and grayscale averaging is 0.004 7 mm, and the image quality is significantly improved, meeting the sub?pixel accuracy requirements. This method does not require the use of complex hardware and does not need to know the parameters of the heat flow field in advance, significantly improving the robustness of high?temperature DIC measurement. It provides a low?cost and high?precision solution for material deformation analysis under extreme working conditions and has important engineering application value.

Oct. 09, 2025
Metrology & Measurement Technology
Vol. 45, Issue 4, 48 (2025)
DOI：10.11823/j.issn.1674-5795.2025.04.03

Recent advances in solid⁃state Rydberg excitons

Yufei ZHAI, Lyupeng YANG, Ming SHAO, Yu YU, Yi WANG, Hao ZHANG, Yifei MA, Mei WANG, and Linjie ZHANG

This review introduces Rydberg excitons as highly excited electron?hole pairs in semiconductors, highlighting their core characteristics: hydrogen?like energy levels, macroscopic quantum properties, strong interactions, and nonlinear optical response. It elaborates on cuprous oxide (Cu2O) as an ideal platform for observing high?order Rydberg states due to its low defect density and dipole?forbidden transitions. The analysis covers key properties of Rydberg excitons revealed through spectroscopic techniques and external field manipulation: micron?scale radii, high polarizability, long lifetimes, and large dipole moments. It further discusses the significantly enhanced long?range interactions between excitons at high principal quantum numbers, which lead to phenomena like excitonic blockade and nonlinear refraction. The discussion extends to the modulation of excitonic properties by external fields, including field?induced energy level splitting, alteration of transition selection rules, and selective excitation of specific states, while also noting the impact of environmental perturbations on spectral features. It is pointed out that Rydberg excitons have great potential for applications in cutting?edge fields such as weak?field sensing, on?chip single?photon devices, quantum simulation, and microwave?to?optical signal conversion due to their distinctive physical attributes and extreme sensitivity to external fields and the environment. The review proposes that in?depth research and exploitation of these properties represent a crucial direction for advancing high?performance quantum information technologies and precision sensing in the future.

Oct. 09, 2025
Metrology & Measurement Technology
Vol. 45, Issue 4, 12 (2025)
DOI：10.11823/j.issn.1674-5795.2025.04.02

Convolutional neural network lens angle calibration method based on cross calibration block

Zixiao TANG, Ruotong WANG and Qingchun LEI

Three?dimensional combustion diagnosis based on tomography technology requires the use of flame images in multiple directions for three?dimensional reconstruction. The accuracy of lens angle calibration directly affects the qua?lity and precision of reconstruction. In order to reduce the error of angle calibration, a Convolutional Neural Network (CNN) lens angle calibration method based on cross calibration block is proposed. A new cross calibration block was designed. Compared with the traditional calibration block, it has more complex spatial structure characteristics, which can enhance the geometric information difference of the image during rotation, help CNN to extract angle features more accurately, and reduce the angle label error in the training set. A CNN based on the Residual Neural Network (ResNet) architecture was built for angle prediction, and CNN training was implemented based on the open?source framework PyTorch to avoid artificial feature design. Experiments were conducted to verify the application effect of the CNN lens angle calibration method based on the cross calibration block. The results show that when the traditional triangular prism calibration block is used for lens angle calibration, the angle label error is large, resulting in low accuracy of lens angle calibration; when the cross calibration block is used for lens angle calibration, the loss function converges faster during model training and the accuracy of lens angle calibration is higher. The convolutional neural network lens angle calibration method based on the cross calibration block shows higher robustness and stronger generalization ability, providing technical support for improving the accuracy of combustion image reconstruction.

Oct. 09, 2025
Metrology & Measurement Technology
Vol. 45, Issue 4, 158 (2025)
DOI：10.11823/j.issn.1674-5795.2025.04.12