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2022 Vol. 44, No. 3

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Survey & Review
Research Progress on Stability of PbS Colloidal Quantum Dots
ZHAO Yiqun, WU Zhenfen, YANG Xiaojie, DENG Dazheng, LIU Xue’e, ZHOU Huiqun
2022, 44(3): 205-211.
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Due to the simple preparation, low cost, and adjustable bandgap via changing their sizes in the near-infrared band, PbS colloidal quantum dots (QDs) have been widely used in many fields such as solar cell, infrared detection, LED, and biological imaging. However, instability limits further practical application. In this study, the instability mechanism of PbS colloidal QDs was investigated, and measures to improve their stability are discussed in terms of preparation, structure, preservation, and application. Measures and mechanisms for further improving stability are proposed, which have great value for their application and development.
Systems & Designs
Development of a Portable Field MRTD Tester
WU Lipeng, GUO Yu, WANG Xuexin, LIU Ruixing, DU Meng, WANG Hao
2022, 44(3): 212-216.
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Currently, the minimum resolvable temperature difference (MRTD) test of a thermal imager is mainly undertaken indoors. To meet the testing requirements of MRTD in other environments, a portable MRTD tester is proposed. This paper describes the development principle of the instrument, optical optimization design, mechanical design, and environment adaptability design, as well as the design points of the blackbody and other components. At present, this instrument has been used in the MRTD test of thermal imagers in outdoor environments and shows accurate results.
Oil Fire Radiation Calculation Based on a Statistical Narrow-Band Model
PENG Wudi, LIU Lixi, CHEN Zhili, TANG Jin, CHEN Lin, HU Tianyou, WANG Haowen
2022, 44(3): 217-224.
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In recent years, oil fire pollution accidents have occurred frequently and caused significant harm. It has become important to study oil fire accidents by extracting fire information through the analysis of spectral characteristics. Many domestic and foreign scholars have established a variety of gas radiation and carbon black radiation models to study fuel combustion; however, few scholars have directly modeled flame spectra to analyze and extract spectral characteristic information on combustion pollution products. In this study, a test platform for the flame spectra of oil was constructed, and the flame spectra of alcohol, 92 gasoline, 95 gasoline, and 0 diesel were measured at a single scale, as was the flame spectra of 0 diesel at multiple scales. The experimental results demonstrate that the flame spectra of the three oils are similar and the radiance increases nonlinearly with an increase in scale. Based on the statistical narrow-band method, a spectral radiation model for the oil flame was established, and a curve fitting degree of 0.895 was obtained based on experimental data. The spectral radiation model can be used to calculate the average radiance and transmittance of oil flames on a large scale, as well as the average transmittance at different flue gas concentrations, which can be helpful for remote fire pollution detection and pollutant concentration inversion.
Equivalent Modeling of PCB for Dynamic Properties Based on The Modal Test
TANG Hexin, ZHANG Wei, GUAN Zhaoyang, LIU Yu, GUO Xiaojun, LUO Fengwang, LI Jiang, ZHANG Ying
2022, 44(3): 225-230.
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It is difficult to establish a finite element model for a PCB owing to the complexity of the internal structure of the substrate, the large variety of components, and irregular distribution. To solve these issues, this article proposes the distribution and structural characteristics of the components on the main processing board of a vehicle thermal imaging camera as an equivalent modeling method of PCB board dynamic performance based on free modal test data. This method uses the original geometric size of the substrate and the components are processed in different ways according to their physical properties and distribution characteristics on the substrate. Finally, the quality of the equivalent model must be kept equal to the actual model, and the free mode is used. The experimental data and least square method were used to deduce the equivalent stiffness of the substrate and the calculation of Poisson's ratio, respectively. The response curve of the main processing board was obtained through a sine frequency sweep test. The damping ratio corresponding to the first two-order responses was calculated using the half-power bandwidth method, and the damping ratio finite element analysis software was used to obtain the response curve of the equivalent model numerical calculation. A comparison of the response curves shows that the equivalent modeling method meets the actual engineering requirements and provides a reference for the equivalent modeling of similar products.
Research on Photon Counting Algorithm Based on Solar Blind Ultraviolet Imaging Detector
YANG Feng, RUAN Ying, LYU Yang, CHANG Wenzhi, GU Yan, ZHAO Weijun, GUO Yiliang, DU Fei, ZHU Bo, JIAO Guoli, WANG Guangzhen
2022, 44(3): 231-235.
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To complete the quantitative analysis of the solar-blind ultraviolet corona signal, a time-domain diffuse round-spot photon-counting algorithm is designed to analyze the image collected by the imaging system. First, the principles of single-photon detection and photon counting are described; second, an imaging detection system based on solar-blind ultraviolet ICMOS is designed. To meet the afterglow response of the screen, the CMOS driver is optimized to make the frame rate up to 390 fps. Then, by analyzing the traditional connected domain photon counting algorithm, a diffuse round spot photon counting algorithm based on the time domain is proposed, and experiments show that the algorithm designed in this study has higher accuracy than the traditional technical algorithm. Finally, through an experiment with an ultraviolet lamp source, it is verified that the designed photon counting algorithm can be implemented in the hardware of the imaging detection system, and the counting effect is good.
Guidance & Countermeasure
Strategy of Barrel Roll and Decoy Deployment Against Infrared Air-to-Air Missile
ZHANG Nan, CHEN Changsheng, SUN Jingguo, LIANG Xuechao
2022, 44(3): 236-248.
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Evasive maneuvers and decoy deployment are effective measures against infrared (IR) air-to-air missiles for fighters. In this study, both aspects were considered: barrel roll maneuver and unpowered point source decoys. For practical purposes, the interference process, movement characteristics, and influence mechanism of the decoy on the missile guidance system are expounded, in which the conditions needed for the barrel roll maneuver and the force of the decoy are considered. In addition, the air-to-air missile is assumed to adopt the true proportional navigation law or augmented proportional navigation law, and the decoys are launched in the conventional mode or emergency mode. Linearized time-varying models and adjoint models for barrel roll maneuvers with decoy deployment influence on missile guidance precision are established. The correctness of these models was verified by a simulation result analysis and comparison. The miss distance is an important parameter for characterizing the performance of an air-defense missile. The average miss distance and percentage of maximum miss distance were proposed to analyze the adjoint model results. Based on the work mentioned above, the barrel roll rate and the transition step maneuver angle of the target aircraft, as well as the simultaneous launch quantity, the period between successive launches, and launch direction policy on the miss distance are analyzed to provide strategic references for fighters against IR air-to-air missiles.
Materials & Devices
Design, Preparation and Characterization of Infrared Low-Emissivity Film
HAN Jianlong, QIU Guihua, ZHANG Ruirong, WANG Wen, WANG Yike, TAN Dongdong, YU Mingxun
2022, 44(3): 249-254.
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Military targets require infrared (IR) stealth performance because of the rapid development of IR detection technology. In this study, an IR low-emissivity film based on a one-dimensional photonic crystal structure was designed and fabricated. The IR reflectance of the low-emissivity film was improved, and the total thickness of the film was reduced by optimizing its construction parameters. The thickness and optical parameters of the Ge and ZnS film prepared via vacuum evaporation were tested using an IR ellipsometer. The IR low-emissivity films with IR emissivities of 0.045, 0.097, 0.174, and 0.346 were prepared via vacuum evaporation after the optimized test results were incorporated into the crystal structure design. The IR reflectivity of the IR low-emissivity films was measured using a Fourier-transform IR spectrometer. The test results agreed well with the calculated results.
Image Processing and Simulation
Sub-pixel Level Image Edge Detection Algorithm Based on Cubic B-spline Wavelet Transform and Franklin Moment
LI Jinpeng, XIONG Xianming, ZENG Qilin, HU Yiwei, DING Ziting
2022, 44(3): 255-261.
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To meet the requirements of high accuracy and strong anti-noise performance of image edge positioning for infrared and visible image registration and precision measurement, a sub-pixel image edge detection algorithm based on the cubic B-spline wavelet transform and Franklin moment is proposed. First, the image edge was decomposed using a cubic B-spline wavelet window function. Under the premise of setting the threshold, according to the principle of wavelet modulus maxima, the initial edge information is detected for each layer, and then the edge points are compared with the points in the 3 × 3 neighborhood in the multi-scale range. Points with similar moduli and amplitudes were reserved to establish a new edge image. Subsequently, a subpixel edge model is established. According to the principle of Franklin moment rotation invariance, the relationship between Franklin moments at all levels after the image edge is rotated to a certain angle is analyzed and the key parameters of the template for calculating the sub-pixel edge points are obtained. The template is moved on the new edge image obtained by wavelet transform and convoluted with the sub-image covered by it, and then the sub-image of the image is obtained from the edge points of the prime level. The experimental results show that, compared with the three algorithms with the current best performance, the algorithm based on the combination of the cubic B-spline wavelet transform and Franklin moments proposed in this paper has higher accuracy and stronger noise resistance. It can better meet the requirements for stable, reliable, and high-precision measurements of infrared and visible image registration.
Fast Finger Vein Recognition Based on a Dual Dimension Reduction Histogram of Oriented Gradient and Support Vector Machine
CHU Hongjia, CHEN Guanghua, WANG Kaixuan
2022, 44(3): 262-267.
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An identification model using a dual-dimension reduction histogram of oriented gradients (HOG) combined with a support vector machine (SVM) is proposed to reduce the time required for finger vein recognition. To solve the problem of high feature dimensionality in the traditional HOG algorithm, the classification ability of the gradient direction interval is first measured using the Fisher criterion. Next, the sequence forward selection method is used to select the gradient direction interval with optimal classification ability to construct a partial direction interval HOG feature. Finally, principal component analysis (PCA) is used to reduce the number of dimensions. An SVM multi-classifier was used for the classification of the FV-USM and THU-FV datasets. The experimental results demonstrate that compared to the HOG+PCA method, the feature dimensions extracted by the dual-dimensional reduction HOG method are reduced by 40%, the recognition time is reduced by 29.85%, the recognition accuracy is 99.17% and 100%, respectively, and the equal error rate is 1.07% and 0.01%, respectively.
Mode Adaptive Infrared and Visible Image Fusion
QU Haicheng, WANG Yuping, GAO Jiankang, ZHAO Siqi
2022, 44(3): 268-276.
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To solve the problems of low contrast and high noise of fused images in low illumination and smoky environments, a mode-adaptive infrared and visible image fusion method (MAFusion) is proposed. Firstly, the infrared and visible images are input into the adaptive weighting module in the generator, and the difference between them is learned through two streams interactive learning. The different contribution proportion of the two modes to the image fusion task in different environments is obtained. Then, according to the characteristics of each modal feature, the corresponding weights of each modal feature are obtained independently, and the fusion feature is obtained by weighted fusion. Finally, to improve the learning efficiency of the model and supplement the multi-scale features of the fused image, a residual block and jump connection combination module are added to the image fusion process to improve the network performance. The fusion quality was evaluated using the TNO and KAIST datasets. The results show that the visual effect of the proposed method is good in subjective evaluation, and the performance indexes of information entropy, mutual information, and noise-based evaluation are better than those of the comparison method.
Anti-occlusion Process of Infrared Target Tracking Based on Correlation Filters
ZHANG Jin, WANG Yuanyu, LIN Dandan, DU Xinyue, LIN Yu, LAN Ge
2022, 44(3): 277-285.
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Focusing on the issue that traditional correlation filters have poor performance in infrared target tracking with occlusion, an anti-occlusion and real-time target-tracking algorithm based on a multi-scale filter tracker and a deep learning detector is proposed. First, the peak response value is calculated using the tracker; if the peak value is less than the threshold, the target is occluded or tracking is lost. Second, the detector stops updating when the target is occluded or tracking is lost. The position of the target changes significantly when it comes in frame again after occlusion, and the speed of target searching with the tracker will be very slow. At this time, a detector is employed to detect the targets in the subsequent frames without loss of tracking accuracy and speed. The peak values are calculated for each target box that is detected by the detector, and the target with a maximum peak value larger than the threshold is tracked. The results of the experiment compared with the multi-scale correlation filter show that the proposed real-time tracking algorithm can not only effectively solve infrared target occlusion, but also has higher tracking robustness and accuracy.
Deep Learning Method for Action Recognition Based on Low Resolution Infrared Sensors
ZHANG Yutong, ZHAI Xuping, NIE Hong
2022, 44(3): 286-293.
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In recent years, action recognition has become a popular research topic in the field of computer vision. In contrast to research on video or images, this study proposes a two-stream convolution neural network method based on temperature data collected by a low-resolution infrared sensor. The spatial and temporal data were input into the two-stream convolution neural network in the form of collected temperature data, and the class scores of the spatial and temporal stream networks were late weighted and merged to obtain the final action category. The results indicate that the average accuracy of recognition can reach 98.2% on the manually collected dataset and 99% for bending, falling, and walking actions, indicating that the proposed net can recognize actions effectively.
Nondestructive Testing
Application of Infrared Thermography for Characterizing Phase Change Process of Porous Media at Pore Scale
WANG Shu, LENG Hang, CHEN Yanling, WANG Changtao, CHEN Zhoulin, YANG Yingying
2022, 44(3): 294-302.
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Infrared thermography (IRT) is a new type of digital nondestructive testing technology that has developed rapidly and has found wide use. However, it still has some shortcomings, such as low accuracy, image noise, and requires a large amount of data. In this study, the phase change processes of paraffin and water in porous materials are characterized by IRT technology at pore scale, and the temperature measurement accuracy and phase interface characterization are optimized. First, the reflective surface (wrinkled aluminum foil) is added to obtain the environmental reflective temperature in the test process to correct the target object temperature; subsequently, guided filtering and principal component thermography (PCT) are used to reduce the noise of IRT images to improve the detection accuracy of the infrared thermal imager for temperature field and phase interface. The experimental results show that the temperature measured by the environmental reflection temperature correction method is closer to that measured by a thermocouple after eliminating the influence of changing environmental temperature; after selecting an appropriate filter radius and filter parameters, the contour of phase interface is clearer, and a better noise reduction effect is obtained. In addition to the good noise reduction effect, PCT makes the phase interface clearer and reduces the amount of processed data by four orders of magnitude. These three processing methods provide better optimization methods and theoretical support for infrared thermal imaging technology to characterize the phase transition process of porous media at the pore scale.
Thickness Evaluation of Weather Resistant Coatings Based on Lock-in Thermography
LI Bo, CHEN Junwei, LIU Zhuoyi, BAI Jie, FAN Lei, ZHANG Cong, GUO Jufu
2022, 44(3): 303-309.
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Owing to the influence of environmental temperature, pollution, moisture, and other climatic factors, metal components of power transmission and transformation systems are prone to premature failure. Generally, weather-resistant materials are coated on metal components. In view of the shortcomings of the existing methods for measuring the coatings, this study uses lock-in thermographic technology to evaluate the thickness. First, the principle and repeatability of the method were verified using standard coating specimens. The results show that the method is reliable and stable for the evaluation of the coating thickness. Subsequently, a wedged weather-resistant coating sample was tested. The error in the measured thickness was within ±5% of the actual value. Therefore, the phase image can be used to effectively measure and evaluate the thickness and uniformity of weather-resistant coatings.
Low-Light-Level
Linear Dynamic Range of Low Resistance Microchannel Plate in DC Mode
YAO Wenjing, LIU Shulin, YAN Baojun, ZHAO Gaofeng, DONG Yongwei, WANG Zhigang, ZHU Kejun, ZHANG Binting, WEN Kaile, WANG Yuman, GU Jianyu
2022, 44(3): 310-314.
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In this paper, a detailed study of the linear dynamic range of the domestic low-resistance microchannel plate (MCP) in DC mode is carried out. In the experiment, a deep ultraviolet light source (low-pressure mercury lamp) is used to excite the MCP with a gold film in order to obtain a wide range of input current, and then various parameters related to the linear dynamic range of the low-resistance MCP are tested. These parameters include resistance, gain, strip current, the maximum and minimum input current, etc. The results show that reducing the resistance can effectively improve the linear dynamic range of the MCP, and the maximum and minimum input current span over 6 orders of magnitude. The low-resistance MCP has a maximum output current of 16% to 19% of the strip current under three different operating voltages. It has comparable performance to the international high-output MCP technology and can be applied in related fields.

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