2024

• Record 445 of
  
  Title:Single line of sight frame camera based on the RadOptic effect of ultrafast semiconductor detector
  
  Author(s):Liu, Yiheng(1,2,3); He, Kai(1); Yan, Xin(1); Gao, Guilong(1); Du, Wanyi(1); Shang, Yang(1); Wang, Gang(1); Wang, Tao(1); Zhang, Jun(4); Tian, Jinshou(1,3); Tan, Xiaobo(4)
  Source: Optics and Lasers in Engineering  Volume: 175  Issue:   DOI: 10.1016/j.optlaseng.2024.108029  Published: April 2024  
  Abstract:A new optical beam splitting method is proposed, based on which the optical frame camera capable of capturing multiple frames in a single exposure is designed and experimentally verified. The operation of the frame camera is based on an ultra-fast response semiconductor detector. It is equipped with an optical beam splitter and an optical imaging module. The ultrafast semiconductor detector receives an optical pulse that produces a transient refractive index change, and ultrafast physical processes are recorded by diffracting the probe laser through the transient phase grating. The interaction of an X-ray pulse with a semiconductor detector to produce a phase grating is simulated, based on the Monte Carlo method. The optical beam splitting mode separates a laser into two optical pulses with a certain time difference in the direction of polarization perpendicular to each other. The imaging module filters the diffracted probe laser in the spectral plane and then images multiple frames. The frame camera was used to record the temporal and spatial distribution characteristics of femtosecond laser pulses with a temporal resolution of 4.1 ps. This frame camera has great potential and value for applying to experimental studies of inertial confinement fusion. © 2024 Elsevier Ltd
  Accession Number: 20240315382269
• Record 446 of
  
  Title:A Comprehensive Equivalent Circuit Model of Silicon Microring Modulators for Photonics-Electronics Codesign
  
  Author(s):Bao, Shenlei(1); Ma, Yingjie(2); Xue, Jintao(1); Wu, Jinyi(1); Qi, Nan(2); Wang, Binhao(1)
  Source: Journal of Lightwave Technology  Volume:   Issue:   DOI: 10.1109/JLT.2024.3382091  Published: 2024  
  Abstract:Silicon microring modulators have huge potential for applications in co-packaged optics (CPO) and optical I/O (OIO) owing to the superior bandwidth, small footprint, and inherent wavelength multiplexing characteristics. To enable efficient and robust optical transceiver systems, codesign and cosimulation environments are essential for optimization of photonic devices, transceiver circuitry and electronic-photonic integrated circuits (EPIC). We introduce a comprehensive equivalent circuit model for single- and dual-segment silicon microring modulators (MRMs), which accurately capture the device behavior during high-speed modulation. This model includes electrical parasitics, nonlinear optical steady state and dynamics, and thermo-optic effects. Model parameters are extracted by curve fitting MRM optical transmission spectrum and small signal characteristics. The simulated eye diagrams exhibit excellent alignment with the measured eye diagrams at data rates of 80Gb/s and 106Gb/s. A cosimulation environment with a MRM driver in 28nm CMOS and a MRM in 130nm silicon photonics is demonstrated on an electronics design automation (EDA) platform. An optical eye diagram at a data rate of 212Gb/s PAM8 is successfully achieved by optimizing the driver equalizer and the MRM two segment ratio. Then an EPIC with photonics-electronics closedloop feedback control algorithm is demonstrated, achieving a significantly larger eye opening after thermal tuning, thanks to the accurate equivalent circuit model of the MRM. IEEE
  Accession Number: 20241415849026
• Record 447 of
  
  Title:Pakistan's 2022 floods: Spatial distribution, causes and future trends from Sentinel-1 SAR observations
  
  Author(s):Chen, Fang(1,2,3); Zhang, Meimei(1,2); Zhao, Hang(4); Guan, Weigui(1,2,3); Yang, Aqiang(1,2)
  Source: Remote Sensing of Environment  Volume: 304  Issue:   DOI: 10.1016/j.rse.2024.114055  Published: April 1, 2024  
  Abstract:Floods are a great threat to Pakistan with increasing concern. As the consequences of increased extreme weather related to climate change, Pakistan experiences severe floods almost every year. This study aims to explore and analysis the actual inundated situation, magnitude, the possible causes of the 2022 devastating floods, and future trends. We presented an enhanced nationwide flood mapping method and compared with other pixel-based image processing techniques including active contours and change detection. These algorithms were applied to Sentinel-1 Ground Range Detected (GRD) Synthetic Aperture Radar (SAR) imagery (10 m spatial resolution) with various land types and inundation scenarios in Pakistan, and were evaluated using other reference flood products. Accuracy evaluation analysis demonstrated that our algorithm has high robustness and accuracy, with the overall accuracy (OA) higher than 0.83 and critical success index (CSI) up to 0.91, and is suitable for automated flood monitoring in near real time. Nearly one-third of the lands were flooded in 2022, and more than half were inundated croplands. Punjab and Sindh provinces were the most severely affected regions, with the proportions of inundated area in 2022 (21.26% and 20.55%) nearly twice of that in 2010 (11.40% and 12.70%), indicating an intensified flooding trend. Analysis of possible influential factors showed that the intense and cumulative rainfall during the monsoon season (June to August) was the major cause of the 2022 flood event. Although the snow melted rapidly in June (the average change in snow depth is ∼10 mm), the overall ablation contributed insignificant amount to the flood water. The glacial lake outburst floods (GLOFs) induced by abnormal April–May heatwave provide water flowed into the tributaries of the Indus River, but are difficult to spread for thousands of kilometers from mountains to the plain downstream. The combination of the intrinsic arid climate and extreme floods exacerbate the already severe situation. © 2024 Elsevier Inc.
  Accession Number: 20240915643476
• Record 448 of
  
  Title:Dynamic Range Study of Microchannel Plate Photomultiplier Tubes under Visible Light Pulse Input
  
  Author(s):Wei, Jianan(1,2); Liu, Hulin(2); Chen, Ping(2,3); Li, Yang(4); Li, Kuinian(2); Wei, Yonglin(2); He, Luanxuan(1,2); Zhao, Xinnan(1,2); Sai, Xiaofeng(2); Liu, Deng(5); Tian, Jinshou(2,3); Zhao, Wei(2,3)
  Source: Guangzi Xuebao/Acta Photonica Sinica  Volume: 53  Issue: 2  DOI: 10.3788/gzxb20245302.0204001  Published: February 2024  
  Abstract:Microchannel Plate Photomultiplier Tube（MCP-PMT），as a high-performance photodetector，has been widely used in various detection experiments in recent years. In previous studies，people mainly focused on improving the sensitivity and temporal resolution of optoelectronic detection devices，while ignoring the key factor of high linearity. With the continuous development of the demand for large dynamic detection，in-depth research and development of MCP-PMT with large dynamic range has become an urgent need for current research.The dynamic range of MCP-PMT is related to many factors，such as the intensity and frequency of input visible light，the material of the microchannel board，and the voltage values applied to each part of MCP-PMT. This article mainly starts from two aspects：the input light pulse frequency and the potential difference applied by the backend of MCP-PMT，and delves into the reasons why the output electrons of MCP-PMT deviate from normal linear multiplication. By combining theoretical analysis and experimental testing，the influence of the repetition frequency of pulse light signals and the potential difference between the second microchannel plate and the anode on the dynamic range of MCP-PMT was studied in detail. When the input light pulse width is 50 ns and the repetition frequency is 500 Hz，the maximum linear output of the anode can reach 2 V（i.e. 40 mA）；when the repetition frequency increases to 1 000 Hz，the linear deviation degree reaches more than 10% when the anode output is 1 V（i. e. 20 mA）；when the input light frequency further increases to 5 000 Hz and the anode output reaches 0.3 V（i. e. 6 mA），the degree of linear deviation has reached about 15%. As the electric potential difference between the second microchannel plate and the anode increases，the maximum linear output voltage of the anode shows fluctuating changes. When the electric potential difference between the second microchannel plate and the anode is around 200 V，the linear output voltage of the anode reaches its peak. As the electric potential difference increases，the linear output voltage of the anode begins to fluctuate，reaching the second peak at a electric potential difference of around 500 V. In this article，we investigated the influence of the frequency of pulse input light and the electric potential difference between the second microchannel plate and the anode on the dynamic range of MCP-PMT，and obtained two conclusions through experimental verification：1）As the pulse input frequency increases，the output voltage of MCP-PMT will detach from the linear region earlier. 2）As the potential difference between MCP2 and the anode increases，the maximum linear output voltage of MCP-PMT does not simply vary monotonically，but exhibits a constantly fluctuating trend in resistance. On this basis，further exploration was conducted on the factors that constrain the dynamic range of MCP-PMT，namely insufficient wall charge supplementation and interference from space charge effects. When the frequency of the input pulse is high，the constraint on the dynamic range of MCP-PMT is mainly related to the former；when the electric potential difference between the second microchannel plate and the anode increases，due to the complex situation of a large number of secondary electrons transferring between the plates to the anode，the dynamic range will be affected by the space charge effect and cannot be directly proportional to the electric field strength. © 2024 Chinese Optical Society. All rights reserved.
  Accession Number: 20240715561760
• Record 449 of
  
  Title:Spectral domain characteristics of partially coherent illumination on grating imaging system
  
  Author(s):Jing, Xinyi(1); Hu, Xiaoying(1); Xu, Liang(2); Liu, Weiguo(1); Hanson, Steen G.(3); Takeda, Mitsuo(1,4); Wang, Wei(1,5)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 13070  Issue:   DOI: 10.1117/12.3013409  Published: 2024  
  Abstract:The grating imaging system has the advantages of high resolution, high sensitivity and strong anti-interference ability, and has been widely used in machine vision, biomedicine and imaging spectroscopy and other fields. The coherence and polarization properties of the light field have different effects on the grating imaging system. This paper studies the polarization system of the grating illuminated by partially coherent light based on the unified theory of polarization and coherence. The experiment is carried out using a sinusoidal amplitude grating of 20 lines per mm. The experimental results show that when the coherence is fixed, as the normalized intrinsic frequency of the grating increases, the second harmonic disappears, leaving only the direct current (DC) component and the first harmonic component, which is consistent with the theoretical result. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.
  Accession Number: 20241315797429
• Record 450 of
  
  Title:Error Correction for Cell Calibration of SO2 Ultraviolet Camera
  
  Author(s):Zhang, Huiliang(1); Li, Faquan(2); Li, Juan(3); Wang, Houmao(4); Zhang, Zihao(1); Guo, Jianjun(1); Wu, Kuijun(1); He, Weiwei(1)
  Source: Guangxue Xuebao/Acta Optica Sinica  Volume: 44  Issue: 6  DOI: 10.3788/AOS230886  Published: March 2024  
  Abstract:Objective Industrial chimneys, ship exhaust, and volcanic eruption processes can emit large amounts of harmful SO2 into the atmosphere, causing serious pollution to the environment. The development of effective SO2 monitoring tools can provide a strong guarantee for atmospheric environmental management. In recent years, SO2 ultraviolet (UV) cameras have been rapidly developed and widely applied by virtue of their high spatio-temporal resolution, high detection sensitivity, and two-dimensional detection imaging capability. Due to the limitation of physical principles, the initial amount measured by the SO2 UV camera is the optical thickness of SO2 gas, which needs to be retrieved into a concentration image with the help of calibration curves, and the accuracy of calibration curves directly affects the accuracy of SO2 concentration results. Cell calibration and differential optical absorption spectroscopy (DOAS) calibration are two main methods for obtaining calibration curves. In terms of equipment cost, easy operation, and system stability, the cell method is significantly better than the DOAS method, but its calibration accuracy is seriously affected by the light dilution effect, reflections on the windows of the calibration cell and filter, and aerosol scattering factors. Additionally, with the rising detection distance, the above factors, especially the influence of the light dilution effect, become increasingly more serious. To improve the calibration accuracy of the cell method, we research the calibration error correction method to address the practical problem of inaccurate cell method calibration in remote SO2 monitoring. Methods In practice, since the factors affecting the accuracy of the cell method are mainly from the light dilution effect, window reflection, and the scattering of aerosols, it is necessary to correct each of these factors. The specific method is as follows. Firstly, the image correction method (ICM) is proposed for correcting the light dilution effect, and the extinction coefficient is obtained by fitting the intensity information of the measurement points at different distances in the UV camera images. Additionally, the optical thickness image of the cell at the measured distance is calculated by the extinction coefficient, and then the calibration curve with the correction of the light dilution effect is obtained. Then, based on the analysis of window reflection and aerosol scattering effect, the influence of the reflection effect and scattering characteristics on the calibration results are quantified. Finally, the calibration curves with the correction of light dilution effect and scattering characteristics are calculated by combining the above influencing factors. Results and Discussions Based on the Etna volcanic plume image data captured by Professor Jonas Gliß from the Norwegian Air Research Institute using a SO2 ultraviolet camera, the Etna volcanic plume SO2 concentration image is retrieved by calibration curves before and after the correction of the light dilution effect. The results are compared with the retrieval results of the DOAS calibration curve, and the results show that the correction of the light dilution effect can reduce the differences between the cell method and the DOAS method from 59.0% to 31.3%, which verifies the effectiveness of ICM in correcting light dilution effect. After correction for reflection and scattering effects, the difference between the cell method and the DOAS method is reduced to 7%. The cell method and DOAS method show good agreement in the time domain after correction, and the fitting curve slope of the primary function of the calibration results is 0.924, with a goodness-of-fit of 0.998. Conclusions The results show that the proposed error correction method for cell calibration of the SO2 UV camera can improve the calibration curve accuracy. The fitting accuracy of the extinction coefficient and the measurement accuracy of the filter reflectance and the quartz window directly affect the accuracy of the calibration curve. The error analysis results show that a 10% shift in the extinction coefficients ΕA and ΕB obtained from channels A and B fitting will cause an error of 8.44% and 13.57% for SO2 column density retrieval respectively, while a 10% shift in background light intensity will result in an error of 4.98% for SO2 column density retrieval. Additionally, a 10% error in the filter reflectance and the quartz window will result in a 6.26% and 1.95% shift in the SO2 column density respectively. Increasing the interval distance of sampling points and the number of sampling points can improve the fitting accuracy of the extinction coefficient. The high-resolution UV spectrometer ensures that the filter reflectance and the quartz window are accurately measured to control errors caused by the reflectance uncertainty. The proposed error correction method for calibration curves solves the limitation that the cell method cannot be applied to monitor the plumes at long distances and high carbon black concentrations, which is important for better applications of SO2 UV cameras in volcanoes, ships, and industrial chimneys. © 2024 Chinese Optical Society. All rights reserved.
  Accession Number: 20241215789360
• Record 451 of
  
  Title:Prediction of Bee Population and Number of Beehives Required for Pollination of a 20-Acre Parcel Crop
  
  Author(s):Jin, Yukun(1); Wei, Tianyi(1); Shi, Jingru(1); Chen, Tingwen(1); Yang, Kai(2,3)
  Source: Signals and Communication Technology  Volume: Part F2203  Issue:   DOI: 10.1007/978-3-031-47100-1_12  Published: 2024  
  Abstract:The decline of the bee population poses threats to the production of considerable types of crops that require pollination. The prediction of the bee’s future population has therefore become a valuable research topic. For Problem one, we tried to solve it in mainly two ways: using the Grey Forecast Model and using differential equations. For data that were missing, we processed them by normalization at first and then regressed to find the abnormal data, and filled the missing data with average data after deleting abnormal data. For the Grey forecast, we use three types of models and compared their respective results with true values to pick the one with the most accurate output and use it to predict the population of bees. For the differential equation method, we simply express the rate of increase in population in terms of several variables (in the differential equation) and solve the equation to obtain the future population. For Problem two, we do a sensitivity test on the bee population. We applied the Random Forest model here to determine the importance of each variable. During the evaluation of the model, we test four sets of data and compare the Random Forest results with the true value. It turned out to be that the final model predicts the population precisely, which has proven that it is reliable. At last, we change the sensitivity of each variable for a 100% change and tell the importance of the variables. For Problem three, we get the model of the possibility of a plant being visited by a bee in a beehive system at any distance, and then we use this matrix to simulate the area and calculate the possibility at any point. After determining a possible lower bound, we can get the area that can reach the bound which is the area the current beehive system can serve. By changing the number and the positions of beehives, we can get the maximum area the system can serve at any time. We can also calculate the possibility considering the planting density and the population of bees so it can be related to problem 1. © 2024, The Author(s), under exclusive license to Springer Nature Switzerland AG.
  Accession Number: 20240515465509
• Record 452 of
  
  Title:Analysis of Bee Population and the Relationship with Time
  
  Author(s):Li, Muyang(1); Liu, Xiaole(1); Qi, Chen(1); Liu, Lexuan(1); Yang, Kai(2,3)
  Source: Signals and Communication Technology  Volume: Part F2203  Issue:   DOI: 10.1007/978-3-031-47100-1_10  Published: 2024  
  Abstract:This essay proposes two methods to analyze bee populations in a given period. The first method is a quantitative analysis of the correlation between time and population, establishing a time–population model for bees. However, this method fails to provide a precise enough result. For improvement, the analysis of bee populations is augmented with more comprehensive factors (both positive and negative), creating a unified measure to calculate the total change in population percentage by assigning weights to each individual factor. During the construction of these two methods, we completed the following five steps: Find relevant data with a numerical correlation between time and population: Data containing relevant information like time and population were downloaded from credible sources. Then, the data were fitted with linear regression to reveal the relationship between the population and time. Find possible factors that affect bee populations: External and internal factors were identified through a literature review of research articles and reputable online sources. Among these, five factors were deemed the most critical and to be used in this chapter later. Assign weights to each factor through the Entropy Weight Method (EWM) and Analytic Hierarchy Process (AHP): With EWM or AHP, a different set of weights was assigned to the factors. However, in this paper, neither of these two was used alone. Instead, a unified model that learns from both methods and hence generates a better weight for each factor is proposed and explained. Analysis of beehives needed to pollinate a 20-acre area: Parameters for the model were identified, defined, and populated using relevant data. Finally, the minimum and the maximum number of beehives that satisfy the requirements were calculated and an average of the values was obtained. Testing of the model on Buhlmann 1985: With the fully calculated weights of different factors through the integrated method, the model was tested to see if the weight assignments were reasonable. To do this, the result obtained from this model is compared with data approached by Buhlmann (1985) as an evaluation of this model. © 2024, The Author(s), under exclusive license to Springer Nature Switzerland AG.
  Accession Number: 20240515465518