2024

• Record 109 of
  
  Title:Adaptive decision threshold algorithm based on a sliding window to reduce BER of free-space optical communication systems
  
  Author(s):Ying, Ruilei(1,2,3); Zheng, Yunqiang(1,3,4); Wei, Sentao(1); He, Yuanchen(1); Xie, Zhuang(1,3); He, Mingze(1,2,3); Wang, Wei(1,3)
  Source:Applied Optics
  Volume: 63  Issue: 13  DOI: 10.1364/AO.519321  Published: May 1, 2024  
  Abstract:Free-space optical communication (FSOC) systems face susceptibility to several factors, such as transmission distance, atmospheric turbulence, and alignment errors. These elements contribute to fluctuations in the signal strength reaching the receiver. The resultant signal fluctuations can result in misjudgments and an elevated bit error rate (BER). This paper proposes an adaptive decision threshold algorithm based on a sliding window (ADTSW). By estimating received signal parameters and delimiting the amplitude interval, the algorithm ensures that the decision threshold tracks signal fluctuations, thereby reducing signal misjudgment. The effectiveness of the algorithm is validated through simulations and experimentation. When the signal peak-to-peak value fluctuates, simulation results demonstrate that the proposed algorithm achieves a 1-order-of-magnitude reduction in BER compared to the traditional fixed decision threshold (FDT) method. Under the influence of weak atmospheric turbulence with different scintillation variance, both simulation and experimentation indicate a 1-order-of-magnitude reduction in BER compared to the FDT method. The ADTSW algorithm proves its capability in minimizing misjudgments, thereby effectively reducing BER and improving communication quality. © 2024 Optica Publishing Group © 2024 Optica Publishing Group (formerly OSA). All rights reserved.
  Accession Number: 20242016084687
• Record 110 of
  
  Title:Theoretical derivation and application of empirical Harvey scatter model
  
  Author(s):Ma, Zhanpeng(1,2); Wang, Hu(1,2,3); Chen, Qinfang(1,2); Xue, Yaoke(1,2,4,5); Yan, Haoyu(1,2,3); Liu, Jiawen(1,2,3)
  Source:Optics Express
  Volume: 32  Issue: 6  DOI: 10.1364/OE.519414  Published: March 11, 2024  
  Abstract:Starting from the Rayleigh-Rice perturbation theory, this paper derives the empirical Harvey scatter model and ABg scatter model applied extensively in optical analysis software packages and verifies the shift-invariant behavior of the scattered radiance in direction cosine space. Using data obtained from multi-wavelength laser scatterometer on carbon nanotube black coating and pineblack coating, we establish the polynomial model based on the sine of the scattering angle plus the sine of the specular reflection angle, i.e., sin θs+sin θ0 and the dual-Harvey model based on sin θs-sin θ0 , respectively. The models are in good accordance with the experimental data and further extend the valid range of empirical models. © 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.
  Accession Number: 20241215761907
• Record 111 of
  
  Title:SPR based dual parameter wide range curling pot shaped photonic crystal fiber sensor
  
  Author(s):Guo, Pengxiao(1); Du, Huijing(1); Li, Jianshe(1); Li, Yuxin(1); Li, Shuguang(1); Yin, Zhiyong(1); Wang, Ruiduo(2); Li, Kaifeng(1); Li, Hongwei(1); Li, Xingwei(1)
  Source:Physica Scripta
  Volume: 99  Issue: 9  DOI: 10.1088/1402-4896/ad6694  Published: September 1, 2024  
  Abstract:This article proposes a curling pot shaped photonic crystal fiber (PCF) sensor based on surface plasmon resonance (SPR), which utilizes two parallel polished surfaces in the cladding to achieve dual parameter measurements of liquid refractive index (RI) and temperature. The mode characteristics and sensing performance of the designed PCF sensor are studied using the finite element method, and the effects of changes in structural parameters such as pore radius, spacing, and gold film thickness on the resonance spectrum are analyzed. The sensing accuracy of the sensor is insensitive to the change of structural parameters, and it has the characteristics of a wide detection range, high sensitivity, and easy manufacture. When the measured RI is in the range of 1.33∼1.42, the maximum RI sensitivity is 20400 nm RIU−1, and the maximum FOM is 483.3 RIU−1. When the temperature ranges from −10 °C to 100 °C, the maximum sensitivity is 15.4 nm °C−1, and the maximum FOM is 0.43 RIU−1. The tight structure design of the sensor core close to the polishing surface and the anti-spill light design with a uniform arrangement of air holes enhance the SPR effect, which is the essential reason for achieving a wide detection range and high sensitivity. © 2024 IOP Publishing Ltd.
  Accession Number: 20243216819469
• Record 112 of
  
  Title:Ultra-precision intelligent modification strategy of pulsed ion beam for optical components (cover paper·invited)
  
  Author(s):Xie, Lingbo(1,2); Shi, Feng(1,2); Tian, Ye(1,2); Gong, Baoqi(1,2); Qiao, Dongyang(1,2); Sun, Guoyan(1,3); Guo, Shuangpeng(1,2); Zhou, Gang(1,2)
  Source:Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering
  Volume: 53  Issue: 10  DOI: 10.3788/IRLA20240283  Published: October 2024  
  Abstract:Objective With the ongoing advancement of optical systems, there has been a growing demand in recent years for precision optical components across various cutting-edge research fields, including EUV lithography lenses, synchrotron radiation X-ray mirrors, and strapdown inertial navigation laser gyro resonators. Ion Beam Polishing (IBP) technology is characterized by its ability to remove complex shapes with excellent stability, absence of edge effects, non-contact non-destructive processing, and high precision. It is commonly employed as the final finishing process for high-precision optical components. While there exist various optimization schemes for the current ion beam shaping machining paths and their velocity distributions, there are still instances where the machine tool's dynamic performance cannot meet the requirements of the optimized machining schemes when processing components with large gradient errors. We introduce a novel Pulsed Ion Beam (PIB) machining technique to overcome the limitations associated with current ion beams in the processing of high-precision optical components. This method not only offers ultra-high removal resolution but also significantly reduces the demands on machine tool dynamics, prevents the formation of extra removal layers, and adeptly achieves precise dwell times at each machining point on the component. Methods This article proposes a new PIB processing method, which adjusts the frequency of the pulse power supply to adjust the period of PIB, and controls the duty cycle to control the duration of the pulse beam current in a single period. It can achieve accurate and controllable material removal in the area that does not require processing by turning off the ion beam current in the non-processing area (Fig.1). Intelligent planning of machining paths using ant colony algorithm (Fig.9). Using ZYGO interferometer to measure the final processing results. Results and Discussions The stability and linearity of PIB have been confirmed (Fig.2), with its removal resolution demonstrated to achieve material removal of 0.33 nm using just 5 pulses. The machining capabilities of traditional IBF and PIB in addressing gradient errors were compared through simulations. The results indicated that when the wavefront gradient of the surface shape error exceeds 0.5 λ/cm, the PIB offers a pronounced advantage in shaping (Fig.6). The implementation of the ant colony algorithm cut ineffective processing paths by 57% (Fig.9). Ultimately, the new processing strategy enabled the acquisition of surfaces with sub-nanometer precision. Following three stages of processing, the RMS error was reduced from 343.438 nm to 0.552 nm (Fig.15). Conclusions This study introduces a new generation of ion beam processing techniques. Compared to traditional IBF methods, the PIB offers superior material removal resolution. By comparing the amounts of material removed with the same sputtering time but varying duty cycles, the PIB system's outstanding stability and linearity in material removal were confirmed. Additionally, five pulses were applied at a frequency of 1 Hz and a 10% duty cycle to sputter hafnium oxide thin films. The comparison of film thicknesses before and after processing confirmed that PIB achieves a sub-nanometer removal resolution of 0.066 nanometers per pulse. Simultaneously, the ACO algorithm was employed to optimize and plan the PIB machining paths, reducing ineffective paths by 57.7%. Ultimately, this processing strategy was used to fabricate an actual monocrystalline silicon mirror, achieving a sub-nanometer precision optical surface of 0.552 nm. This verifies the superior performance of the PIB processing strategy and system in achieving high-precision optical surfaces. It represents a more flexible, accurate, and efficient ion beam processing technique. © 2024 Chinese Society of Astronautics. All rights reserved.
  Accession Number: 20244317254044
• Record 113 of
  
  Title:FPM-WSI: Fourier ptychographic whole slide imaging via feature-domain backdiffraction
  
  Author(s):Zhang, Shuhe(1,2,3); Wang, Aiye(1,4); Xu, Jinghao(1,4); Feng, Tianci(1,4); Zhou, Jinhua(3); Pan, An(1,4)
  Source:Optica
  Volume: 11  Issue: 5  DOI: 10.1364/OPTICA.517277  Published: May 20, 2024  
  Abstract:Fourier ptychographic microscopy (FPM) theoretically provides a solution to the trade-off between spatial resolution and field of view (FOV), and has promising prospects in digital pathology. However, block reconstruction and then stitching has become an unavoidable procedure for reconstruction of large FOV due to vignetting artifacts. This introduces digital stitching artifacts, as the existing image-domain optimization algorithms are highly sensitive to systematic errors. Such obstacles significantly impede the advancement and practical implementation of FPM, explaining why, despite a decade of development, FPM has not gained widespread recognition in the field of biomedicine. We report a feature-domain FPM (FD-FPM) based on the structure-aware forward model to realize stitching-free, full-FOV reconstruction. The loss function is uniquely formulated in the feature domain of images, which bypasses the troublesome vignetting effect and algorithmic vulnerability via feature-domain backdiffraction. Through massive simulations and experiments, we show that FD-FPM effectively eliminates vignetting artifacts for full-FOV reconstruction, and still achieves impressive reconstructions despite the presence of various systematic errors. We also found it has great potential in recovering the data with a lower spectrum overlapping rate, and in realizing digital refocusing without a prior defocus distance. With FD-FPM, we achieved full-color and high-throughput imaging (4.7 mm diameter FOV, 336 nm resolution in the blue channel) free of blocking-and-stitching procedures on a self-developed Fourier ptychographic microscopy whole slide imaging platform. The reported FD-FPM shows the value of FPM for various experimental circumstances, and offers physical insights useful for the developments of models for other computational imaging techniques. The reported platform demonstrates high-quality, high-speed imaging and low cost, and could find applications in many fields of biomedical research, as well as in clinical applications. © 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.
  Accession Number: 20242116151728
• Record 114 of
  
  Title:Multimodal fusion-based high-fidelity compressed ultrafast photography
  
  Author(s):He, Yu(1); Yao, Yunhua(1); He, Yilin(1); Jin, Chengzhi(1); Huang, Zhengqi(1); Guo, Mengdi(1); Yao, Jiali(1); Qi, Dalong(1); Shen, Yuecheng(1); Deng, Lianzhong(1); Wang, Zhiyong(2); Zhao, Wei(3); Tian, Jinshou(3); Xue, Yanhua(3); Luo, Duan(3); Sun, Zhenrong(1); Zhang, Shian(1,4,5)
  Source:Optics and Lasers in Engineering
  Volume: 181  Issue:   DOI: 10.1016/j.optlaseng.2024.108363  Published: October 2024  
  Abstract:Featuring high frame rate and large sequence depth in a single shot, compressed ultrafast photography (CUP) has emerged as an outstanding tool for observing ultrafast phenomena, especially those unrepeatable or irreversible ones. However, the lower image quality in CUP due to high data compressive ratio has always been a tough issue, hampering its further applications in capturing the transient scenes with fine structural information. To overcome this disadvantage in CUP, here we report a multimodal fusion-based compressed ultrafast photography to achieve high-fidelity ultrafast imaging, termed MF-CUP. MF-CUP simultaneously records the dynamic scenes with three different imaging models, involving CUP, transient imaging and spatiotemporal integration imaging. Attributed to the joint acquisition of the dynamic scenes from different imaging models and the multimodal fusion image reconstruction algorithm enabled by untrained neural network, MF-CUP acquires the higher fidelity in both spatial and temporal domains compared with traditional CUP. Both the simulation and experimental results demonstrate that MF-CUP can effectively enhance the accuracy and quality of reconstructed images. Given this high-fidelity imaging ability of MF-CUP, it will provide a powerful tool for the detection of ultrafast dynamics with fine details. © 2024 Elsevier Ltd
  Accession Number: 20242316218568
• Record 115 of
  
  Title:Research and Design of Wavefront Performance of Reflective Laser Beam Expander Under Thermal Environment
  
  Author(s):Wenjie, Fan(1); Zhaohui, Li(1); Yong, Liu(1); Huan, Zhang(1); Shasha, Yin(1)
  Source:Zhongguo Jiguang/Chinese Journal of Lasers
  Volume: 51  Issue: 14  DOI: 10.3788/CJL240531  Published: July 2024  
  Abstract:Objective The performance of a beam expander, as a key component for improving laser divergence angle in high-energy laser emission systems, directly affects the collimation and beam quality of laser emitted by the system. However, when all-weather operation is required, changes in the ambient temperature affect the wavefront stability of the internal beam expander in high-energy laser emission systems. The conventional design concept of passive thermal compensation is to compensate for the thermal displacement of optical surfaces via the reverse expansion deformation of two different material support structures in a thermal environment. However, the structural form of supporting structures connected by different materials can generate thermal stress in the thermal environment, thus resulting in the uncontrollable deformation of the structure and increasing the design risk of the system. In this study, a new design method for injection thermal compensation is proposed, which compensates for thermal deformation via the flexible force of the silicone-rubber layer. This method offers good thermal compensation and avoids the irregular deformation and stress generation of the support structure during thermal compensation. We hope that our basic research can provide new ideas and data support for the thermal compensation design of coaxial reflective systems. Methods In this study, a laser-beam expander was regarded as the research object. First, the effect of temperature change on the wavefront root mean square (RMS) and Zernike fringe coefficients of the beam expander in the temperature range of 0 ℃ to 40 ℃ was investigated via integrated optomechanical analysis. Subsequently, a temperature test platform was established, and the accuracy of the integrated simulation results was discussed using wavefront test data from 0 ℃ to 40 ℃ . Next, to accommodate the significant changes in the power of the system during temperature rise and fall, a method for designing the thermal compensation of the injection rubber was proposed. The relationship between the thickness and diameter of the silicone rubber layer and the thermal-compensation effect was investigated via integrated optomechanical analysis, and the suitable thickness of the silicone-rubber layer for the thermal compensation of laser-beam expanders was determined. Finally, experimental testing and simulation analysis were performed, which verified that the laser-beam expander designed with thermal compensation presents favorable thermal-environment adaptability and satisfies the usage requirements. Results and Discussions The simulation analysis results are consistent with the experimental test results (Fig. 11), thus indicating that the first-order astigmatism and coma of the system vary marginally within 0 ℃ to 40 ℃, and that the power change caused by the change in the distance between the primary and secondary mirrors contributes primarily to the wavefront increase of the system (Fig. 7 and Fig. 8). The analysis on the thermal compensation of the beam expander shows that both the thickness and diameter of the rubber layer affect thermal compensation, and that the effect of the rubber-layer thickness on thermal compensation is more significant. The thickness of the silicone-rubber layer ranges from 0.15 mm to 0.25 mm. As the thickness increases, the system wavefront RMS and power decrease. When the thickness of the adhesive layer exceeds 0.25 mm, overcompensation occurs, and the power changes from positive to negative (or from negative to positive), whereas the RMS of the system increases with the rubberlayer thickness (Fig. 12). By considering thermal compensation in the design of the laser-beam expander, the wavefront RMS and beam quality equivalent β factors at 0 ℃, 20 ℃, and 40 ℃ are 0.373λ@633 nm, 0.0319λ@633 nm, 0.397λ@633 nm and 1.385, 1.331, and 1.402, respectively, thus demonstrating the good thermal stability of the beam expander (Fig. 14). Conclusions In the present study, the wavefront variation of laser-beam expanders in the temperature range of 0 ℃ to 40 ℃ is revealed. Because the power of beam expanders is sensitive to temperature change, a new passive thermal-compensation design method suitable for coaxial reflective optical systems is proposed. The compensation design involves injecting silicone rubber on the back of optical components to compensate for the change in optical spacing with the expansion or contraction flexible force of the silicone-rubber layer in the thermal environment. It can effectively reduce the occurrence of uncontrollable thermal stress and deformation in the thermal environment caused by the connection of different material support structures in conventional, passive, mechanical, non-thermal designs. After considering thermal compensation, the wavefront variation of the laser-beam expander within the temperature range of 0 ℃ to 40 ℃ remain less than 0.0078λ@633 nm. Additionally, β does not exceed 0.071, which signifies that the usage requirements are satisfied. © 2024 Science Press. All rights reserved.
  Accession Number: 20243116794044
• Record 116 of
  
  Title:Observation of the colliding process of plasma jets in the double-cone ignition scheme using an x-ray streak camera
  
  Author(s):Liu, Zhengdong(1,2); Wu, Fuyuan(3,4); Zhang, Yapeng(1,2); Yuan, Xiaohui(3,4); Zhang, Zhe(4,5,6); Xu, Xiangyan(7); Xue, Yanhua(7); Tian, Jinshou(7); Zhong, Jiayong(1,2,4); Zhang, Jie(3,4,5)
  Source:Physics of Plasmas
  Volume: 31  Issue: 4  DOI: 10.1063/5.0188056  Published: April 1, 2024  
  Abstract:The double-cone ignition scheme is a novel approach with the potential to achieve a high gain fusion with a relatively smaller drive laser energy. To optimize the colliding process of the plasma jets formed by the CHCl/CD shells embedded in the gold cones, an x-ray streak camera was used to capture the spontaneous x-ray emission from the CHCl and CD plasma jets. High-density plasma jets with a velocity of 220 ± 25 km/s are observed to collide and stagnate, forming an isochoric plasma with sharp ends. During the head-on colliding process, the self-emission intensity nonlinearly increases because of the rapid increase in the density and temperature of the plasma jets. The CD colliding plasma exhibited stronger self-emission due to its faster implosion process. These experimental findings effectively agree with the two-dimensional fluid simulations. © 2024 Author(s).
  Accession Number: 20241916063677
• Record 117 of
  
  Title:Color-restoring and energy-saving imaging monitoring for intelligent offshore engineering
  
  Author(s):Quan, Xiangqian(1); Chen, Xiangzi(2,4); Wei, Yucong(1,3); Li, Zizheng(5); Li, Yun(6); Yan, Peng(6)
  Source:Ocean Engineering
  Volume: 311  Issue:   DOI: 10.1016/j.oceaneng.2024.118951  Published: November 1, 2024  
  Abstract:Images play a crucial role in artificial intelligence (AI) for offshore engineering, which provide a large amount of data for machine intelligence to ensure the safe operation and maintenance of offshore structures. However, due to the attenuation of sunlight in water or monitoring at nighttime, underwater imaging monitoring systems need a light source, which consumes a lot of energy and impacts the load capacity of an offshore monitoring system. In addition, due to the nonlinearity of attenuation at different wavelengths, underwater images generally suffer from color deviation, tending to be blue and green, which decreases the accuracy of machine learning and intelligent recognition in unmanned offshore engineering. In order to reduce energy consumption and enhance color restoration, we proposed and designed a three-detector underwater imaging system (TD&TP-UIS) based on a prism, in which three detectors were used to enhance the utilization efficiency of light, and a gated band coating was designed on the prism to enhance the color reproduction. A series of experiments were carried out in water tanks, pools, Qiandao Lake, and other places to verify the advantage of color restoration and energy saving using the TD&TP-UIS. © 2024 Elsevier Ltd
  Accession Number: 20243416890329
• Record 118 of
  
  Title:Dielectric terahertz metasurface governed by symmetry-protected BIC for ultrasensitive sensing
  
  Author(s):Yan, Hui(1,2,3); Fan, Wen-Hui(1,3,4); Jiang, Xiao-Qiang(1,3); Chen, Xu(1); Qin, Chong(1,3); Wu, Qi(1,3)
  Source:Physica Scripta
  Volume: 99  Issue: 8  DOI: 10.1088/1402-4896/ad59da  Published: August 1, 2024  
  Abstract:The non-radiative bound states in the continuum (BIC) have attracted much attention in achieving theoretically infinite quality (Q) factor. In this paper, a dielectric terahertz metasurface with C 4v symmetry is proposed, and a toroidal dipole resonance is easily obtained under incident plane wave. Moreover, by slightly tuning the asymmetry parameter δ to break the in-plane symmetry of the structure (side length perturbation), a magnetic dipole BIC mode radiates as quasi-BIC (QBIC) with extremely narrow linewidth and ultrahigh Q of 1.2 × 104 at δ = 0.4 μm. It shows significant performance in THz sensing with the sensitivity around 446 GHz/RIU and figure of merit (FoM) up to 2267. The designed metasurface in the case of symmetry-breaking by position perturbation also achieves ultrasensitive sensing. Additionally, the effects of geometric parameters on the resonance modes have been comprehensively investigated. Our work provides a route to design symmetry-protected BIC metasurface with simple structure, and the Q factor as well as resonant frequency can be controlled using a single geometric parameter, which may facilitate designing high-performance metasurface in sensing applications. © 2024 IOP Publishing Ltd.
  Accession Number: 20242716654606
• Record 119 of
  
  Title:Research on the Image-Motion Compensation Technology of the Aerial Camera Based on the Multi-Dimensional Motion of the Secondary Mirror
  
  Author(s):Zhang, Hongwei(1); Qu, Rui(1); Chen, Weining(1); Guo, Huinan(1)
  Source:Applied Sciences (Switzerland)
  Volume: 14  Issue: 16  DOI: 10.3390/app14167079  Published: August 2024  
  Abstract:Targeting the dynamic image-motion problem of aerial cameras in the process of swing imaging, the image-motion compensation technology of aerial cameras based on the multi-dimensional motion of the secondary mirror was adopted. The secondary mirror was used as the image-motion compensation element, and the comprehensive image-motion compensation of the aerial camera was realized through the multi-dimensional motion of the secondary mirror. However, in the process of compensating for the image motion, the secondary mirror would be eccentric and inclined, which would cause the secondary mirror to be off-axis and affect the image quality. Therefore, a misalignment optical system model was established to study the relationship between the deviation vector and the misalignment of the secondary mirror, and the influence of the secondary mirror’s motion on the distribution of the aberration was analyzed. In order to verify the image-motion compensation ability of the multi-dimensional motion of the secondary mirror, an experimental platform was built to conduct a laboratory imaging experiment and flight experiment on the aerial camera. The experimental results showed that the dynamic resolution of the aerial camera using the image-motion compensation technology could reach 74 lp/mm, and the image-motion compensation accuracy was better than 0.5 pixels, which met the design expectation. In conclusion, the image-motion compensation technology is expected to be applied to various high-precision optical imaging as well as optical detection systems. © 2024 by the authors.
  Accession Number: 20243516970428
• Record 120 of
  
  Title:Universal high-frequency monitoring methods of river water quality in China based on machine learning
  
  Author(s):Zhang, Yijie(1,2,3); Li, Weidong(4); Wen, Weijia(1,2,3); Zhuang, Fuzhen(5,6); Yu, Tao(7); Zhang, Liang(1,2,3); Zhuang, Yanhua(1,2,3)
  Source:Science of the Total Environment
  Volume: 947  Issue:   DOI: 10.1016/j.scitotenv.2024.174641  Published: October 15, 2024  
  Abstract:The in-situ high-frequency monitoring of total nitrogen (TN) and total phosphorus (TP) in rivers is a challenge and key to instant water quality judgment and early warning. Based on the physical and chemical association between TN/TP and sensor-measurable predictors, we proposed a novel "indirect" measurement method for TN and TP in rivers. This method combines the timeliness of multi-sensor and the accuracy of intelligent algorithms, utilizing 188,629 data sets from 131 water monitoring stations across China. Under 5 algorithms and 4 predictor group scenarios, the results showed that: (1) extra tree regression (ETR) with 6 predictors exhibited the best precision, and the mean determination coefficient (R2) of TN and TP inversion across 131 stations reached 0.78 ± 0.25 and 0.79 ± 0.22 respectively; (2) among 6 potential predictors, the importance degrees of temperature, electrical conductivity, NH4-N, and turbidity were greater than that of pH and DO, and >80 % of stations exhibited acceptable prediction accuracy (R2 > 0.6) when the number of predictors (P) ranged from 4 to 6, which showed good tolerability to predictor variations; (3) the accurate classification rates of water quality standard (ACRws) of all stations based on TN and TP reached 90.41 ± 6.96 % and 92.33 ± 6.41 %; (4) in 9 regions/basins of China, this method showed universal application potential with no significant prediction difference. Compared with laboratory test, water quality automatic monitoring station, and remote sensing inversion, the proposed method offers high-frequency, high-precision, regional adaptability, low cost, and stable operation under rainy, cloudy, and nighttime conditions. The new method may provide important technological support for timely pollutant tracing, pre-warning, and emergency control for river pollution. © 2024 Elsevier B.V.
  Accession Number: 20242916716636