Infrared Differential Detectors: A New Paradigm Beyond the Limits of BLIP
Infrared Differential Detectors: A New Paradigm Beyond the Limits of BLIP
Infrared Differential Detectors: A New Paradigm Beyond the Limits of BLIP
Infrared Differential Detectors: A New Paradigm Beyond the Limits of BLIP
Infrared Differential Detectors: A New Paradigm Beyond the Limits of BLIP
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Lu Wei, Li Xiangyang, Li Ning, Zhang Yan, Ma Ding, Wang Jiqing, Zhen Honglou, Zhou Xiaohao, Wang Shaowei
2025,46(6):1-9
Abstract:
Although long-wavelength infrared imaging technology is crucial in applications such as terrestrial remote sensing and astronomy, it faces a fundamental challenge from the overwhelming thermal background radiation. This background photon flux often pushes conventional detectors to the limits of their background-limited performance (BLIP). The main limiting factor here is not the intrinsic noise of the detector, but the shot noise of the background itself. In this paper, a key classification is demonstrated to distinguish between two superficially similar but fundamentally different detection architectures (difference detector and differential detector). According to the application and implementation of the detector, the background photocurrent of the conventional difference detector sets a background-determined threshold for the detectable signal difference, while the differential detector is a device that directly measures the differences of the target physical quantities at the physical perception level. Only the weak difference signals are integrated, resulting in extensive cumulative sampling to improve the signal-to-noise ratio to an unprecedented level. In particular, the differential detection technology path based on the quantum well infrared photodetector (QWIP) is introduced. QWIP provides an ideal physical basis for realizing high-performance long-wavelength infrared differential detectors with its extremely low dark current, precise electrical controllability and intrinsic spectral selectivity, and has made significant progress in experiments. Finally, Fisher information theory and Cramer-Rao bound are used to provide rigorous theoretical support for differential detectors.
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LI Jing-feng, LIU Ming, ZHANG Jin-yu, Fu Wei
2025,46(6):10-14
Abstract:
Compared with the monochromatic detector, the two-color detector has higher detection accuracy and is the typical representative of third-generation infrared detectors. Type-II superlattice has outstanding advantages such as wide absorption spectrum and high uniformity, and can be used to prepare two-color detectors. Annealing technology can improve the performance of two-color type-II superlattice devices by improving the quality of sidewall passivation and the quality of contact between materials and electrodes. By conducting a series of annealing experiments at different temperatures on the device, the effect of annealing on the performance of mid-/long-wavelength two-color type-II superlattice infrared focal plane devices is analyzed and studied. By optimizing the annealing process, the long-wavelength corresponding impedance of the pnp structure device can be increased by 4.6 times, and the long-wavelength corresponding impedance of the npn structure device can be increased by 31%. Compared with improving device performance by optimizing material structure and device structure, annealing has outstanding advantages such as high efficiency and simplicity. This study has certain reference significance for the performance improvement of mid-/long-wavelength twocolor type-II superlattice infrared focal plane devices.
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SU Lei-sheng, XUE Ben-chi, QIU Ji-jun
2025,46(6):15-23
Abstract:
In the research field of infrared transparent conductive films, alleviating the contradiction between high transmittance and low resistivity is a major scientific challenge. The molecular beam epitaxy (MBE) technique is used to study the effect of growth temperature on the electrical properties of indium-doped cadmium selenide (CdSe:In) films, and a transparent conductive film with a high mobility of 204 cm2·V-1·s-1 and a low resistivity of 6.95×10-5 Ω·m is prepared. The film exhibits a high transmittance of more than 87% in the 1－4 μm waveband. The results of the temperature-dependent characteristics study show that there are three temperature ranges for the conductivity of the film, which are distinguished by the transition of the carrier transportation mechanism. Compared with other reported mid-infrared transparent conductive films, it can be seen that the CdSe:In film shows obvious advantages in carrier mobility and transmittance. This study lays an experimental and theoretical foundation for the application of CdSe:In films in mid-infrared detectors.
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2025,46(6):24-33
Abstract:
In view of the importance of the concentration of engine tail flame components to the infrared spectrum radiation intensity, an efficient infrared spectrum concentration solution model is proposed, namely the CARS-CNN-GRU model which combines the competitive adaptive reweighted sampling (CARS) algorithm with the convolutional neural network (CNN)-gated recurrent unit (GRU) deep learning algorithm. This method uses the CARS algorithm to select the key wavelengths and obtain the tail flame component concentration information. Then the CNN-GRU model is used to perform long-range dependency analysis on the sequence data to achieve multi-scale feature extraction. Simulation results show that compared with the traditional models, the CARS-CNN-GRU model has higher accuracy in solving H2O and CO2 concentrations. Its root mean square error (RMSE) is reduced to 0.0014 and 0.0017, respectively. The R2 value is 0.999 and 0.998, respectively; the mean absolute error (MAE) is 0.0011 and 0.0014, respectively. The CARS-CNN-GRU model proposed in this paper shows superior performance in solving infrared spectral concentration. Compared with traditional methods, it has higher accuracy, stability and reliability, and provides strong support for stealth technology, environmental monitoring and combustion efficiency evaluation in the military and civil aviation fields.
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Ma Yuan, Long Jianyu, Xu Sicong, Zhou Wen
2025,46(6):34-41
Abstract:
Terahertz (THz) technology has great potential in the next generation of wireless communications due to its abundant spectrum resources. Electronic device-based systems have very limited device bandwidth when used to generate THz waves, which restricts the growth of system throughput, while photonics-aided THz systems are expensive and complex in structure. To solve this problem, a terahertz system using Delta-Sigma modulation (DSM) is proposed. In the study, a set of 0.15 THz 1024-QAM signals is generated and a 2-meter free-space wireless THz wave transmission system is successfully demonstrated. In addition, inspired by the rapid error propagation in DSM demodulation, a method combining digital signal processing (DSP) with complex-valued neural network (CVNN) is proposed to improve the bit error rate (BER) performance of 1024-QAM signals. When the BER soft-decision is 2×10-2, the sensitivity of the receiver is improved by 0.5 dB. The method proposed in this paper can effectively solve the problems caused by noise in traditional quadrature amplitude modulation (QAM) to improve the spectrum efficiency of electronic devices with insufficient bandwidth.
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SHI Jun, CUI Lin-li, ZHANG Min, SHEN Zhong-ping, YANG He-qun
2025,46(6):42-48
Abstract:
In order to understand the characteristics and dynamic changes of the eco-climate in the Yangtze River Delta (YRD) urban agglomeration, based on the daily observation data of air temperature, precipitation, relative humidity and wind speed from 111 meteorological stations in the region, as well as the MODIS normalized difference vegetation index (NDVI) and land surface temperature (LST) data, remote sensing, GIS and principal component analysis (PCA) methods were used, and the existing remote sensing ecological index (RSEI) was improved. A regional integrated eco-climatic index (IECI) model was constructed from the aspects of dryness/wetness, comfortableness, greenness, heat and air cleanliness, and the dynamic change characteristics of the eco-climate in YRD urban agglomeration were analyzed. The results showed that during the period from 2001 to 2018, the fractional vegetation cover (FVC) of the urban agglomeration increased significantly with a linear trend of 2.80% per decade, the mixed layer height (MLH) decreased significantly at a rate of 51.3 m per decade, and the regional IECI decreased significantly with a linear trend of 0.10 per decade, showing a regional overall decreasing trend. Human activities and urbanization have significant effects on eco-climate change in the YRD urban agglomeration. It is necessary to strengthen the protection and improvement of eco-climate while promoting economic and social development, so as to achieve harmonious coexistence between humans and nature.
Volume 46,2025 Issue 6
Articles
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Research on Design and Calibration of Terahertz source Based on Difference Frequency Generation
ZHU Jun-feng, ZHANG Gui-ming, ZHANG Ting, HU Xiao-ning, Wang Tong, LIU Ming, DU Zhi-qiang, JIANG Jin-chun
Abstract:
The difference-frequency module serves as the core component of the tunable terahertz source, with its performance directly determining the efficiency of terahertz generation. To enhance the terahertz output power, this study designed laser beam reduction systems with 2:1 and 3:1 ratios based on laser parameters after optical power amplification. This ensures consistent beam diameters for optimized spatial mode matching. Through polarization calibration, the lasers maintain linear horizontal polarization to fully exploit the crystal's maximum nonlinear coefficient. Post-alignment, the dual beams achieve precise spatial overlap, forming a focused spot of approximately 22 μm after passing through the focusing lens, thereby significantly enhancing difference-frequency conversion efficiency. Experimental verification confirms that this module has successfully enabled terahertz wave generation.
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A Stirling-cooled fast start Infrared Detector
Abstract:
The integrated Stirling-cooled infrared focal plane graphics component has the characteristics of small size, low power consumption, and high reliability, and is widely recognized in various infrared complete systems. However, existing detectors hardly satisfy the strict startup-time requirements of long-range missile weapon systems for guidance-based combat. This article analyzes the factors that affect the startup time of infrared focal plane detectors and proposes a new design concept. By designing a micro - Dewar and a refrigerator drive controller while keeping the original detector’s performance and the optical, mechanical, and electrical interfaces unchanged, rapid startup is achieved. Experimental results indicate that, under this condition, a considerable reduction in cool - down time has been obtained. The cool - down time can be reduced to within 3 minutes and 30 seconds at normal temperature. This significantly improves the detector’s fast cool-down capability and meets the project requirements.
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PM2.5 signal recognition and interpretable retrieval based on satellite infrared data
WANG Gen, YUAN Song, YE Song, FAN Chuan-yu
Abstract:
Particulate matter with a diameter less than 2.5 microns (PM2.5) on the ground has a negative impact on human health and the economy. Most methods obtain PM2.5 from satellite derived aerosol optical depth (AOD) indirect products or daytime atmospheric top reflectance. The purpose of this paper is to directly use the advanced geosynchronous radiation imager (AGRI) infrared data from Fengyun-4B satellite and artificial intelligence models to retrieve PM2.5 with spatial and temporal resolution of 4 kilometers and 15 minutes in the Yangtze-Huaihe region in near-real time throughout the entire time period (including day and night). Firstly, explore the signal response of AGRI brightness temperature to different levels of PM2.5 in different seasons; Secondly, a study on AGRI brightness temperature retrieval of PM2.5 was conducted based on the random forest method in different seasons. The experimental results showed that the PM2.5 correlation coefficients obtained from the seasonal retrieval were all over 0.87; Finally, based on SHapley Additive exPlanations (SHAP), the model was interpretable and the contribution of geographic information to PM2.5 was found to be significant. And further explored the application of the products mentioned in this paper.
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Study on the solution of atmospheric transmittance based on HO-RF
Abstract:
In order to improve the efficiency and accuracy of obtaining atmospheric transmittance parameters in infrared radiation test, this study proposes an atmospheric transmittance solution model based on HO-RF algorithm. The model takes the key environmental factors such as temperature, humidity, operating distance and atmospheric pressure as input, and establishes a regression solution model based on the measured data, so as to realize the rapid and accurate solution of atmospheric transmittance. The simulation results show that compared with the traditional BP neural network and RF model, the proposed HO-RF model performs better in terms of solution accuracy. The root mean square error ( RMSE ) is reduced to 0.010745, the R2 value is 0.95877, and the mean absolute error ( MAE ) is 0.0080021. The model proposed in this study can effectively reduce the complexity of experimental operation. Compared with the traditional method, it has higher accuracy, stability and reliability, and improves the efficiency of infrared characteristic test of fighter aircraft, which has good practical application value.
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An Intelligent Identification Method and Its Application for Downhole Fluid Types Based on Big Data in Near-infrared Spectroscopy
Kong Sun, Shen Yang, Yu Qiang, Chu Xiaodong, Bao Zhongli, Zuo Youxiang
Abstract:
Although COSL has successfully developed downhole optical spectrum analyzers, there are still shortcomings in interpretation, especially intelligent fluid identification driven by downhole spectral data in real time. In this paper, an intelligent fluid identification method driven by spectral data in real time is proposed for the first time. Firstly, based on a large number of measured spectral and fluid data, a database of various fluids is established. The spectral data and fluid types in the database are then preprocessed separately. The spectral data of 256 channels are further reduced by principal component analysis, and the first 10 principal components are chosen as input variables. Fluids are divided into 5 types (output variables): gas, oil, water, slurry (emulsified fluid, or invalid measurement), oil/gas-water mixture. Next, 23 pattern recognition models are used for modeling of fluid identification, including various trees, discriminants, support vector machines, K-nearest neighbor methods, artificial neural networks and so on. All the models are then analyzed and compared, and the best model is selected to be embedded in the formation test tool. The test accuracy of the 23 models after training is 78.1% - 99.9%. The artificial neural network is the best (accuracy of 99.9%). Finally, the spectral data from more than 40 sampling stations are employed to further examine the best model. The results show that the best model can accurately predict fluid types. The new intelligent identification method lays a solid foundation for eliminating the influence of water on the oil and gas spectra and analyzing the composition of oil and gas more accurately, thus reducing operation risks and saving operation time and costs.
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Study on the Frustum-shaped defects on the surface of HgCdTe film prepared by Liquid Phase Epitaxial growth
Yang Meihua, Xing Xiaoshuai, Yang Haiyan, Hu Yilin, Li Qian, Wang Lijun
Abstract:
In order to reduce the influence of the defects of telluride cadmium mercury (HgCdTe) thin films grown by liquid phase epitaxy (LPE) on the performance of infrared detectors, a special type of surface defects, the frustum-shaped defect, was systematically studied by means of scanning electron microscopy, energy dispersive X-ray spectrometer, focused ion beam and comparative experiments. The size of these defects ranges significantly, from approximately 150 to 400 micrometers, and under an optical microscope, they exhibit a morphology resembling a frustum with a concave center. Compositional analysis revealed no significant differences between the surface of the defect and the normal film morphology. Further analysis of the interface between the tellurium zinc cadium (CdZnTe) substrate and the HgCdTe film indicated that these penetrating defects orginate from triangular telluride inclusions with central holes on the CdZnTe substrate, and the size of tellurium inclusions is almost above 20 μm. Therefore, by improving the quality of the CdZnTe substrate and enhancing substrate screening, the frustum-shaped defects in HgCdTe films can be reduced, thereby improving the quality of HgCdTe epitaxial materials. This enhancement is essential to meet the demands of high-performance infrared detector development.
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A high operating temperature long wave mercury cadmium telluride detector with large charge handling capacityXing Yanlei Song Shufang
Abstract:
In recent years, the high operating temperature device with its light weight, small size, low heat consumption characteristics, while reducing the cost of the same level of performance as the low temperature detector advantages, gradually become the focus of infrared research. The large charge processing capability has the advantages of wide dynamic range (DR), high sensitivity, strong signal detection, etc., and is widely used in LiDAR, astronomical observation and other fields. In this paper, a long-wave mercury cadmium telluride detector with high charge processing capacity and operating at high temperature is introduced. The charge processing capacity can reach 40Me- at 15μm pixel spacing. The main performance of the device at different operating temperatures is compared and analyzed. At 110K, the effective pixel rate can reach 98.5%, the noise equivalent temperature difference is 28mK, and the peak quantum efficiency is 40%. Compared with the performance at 77K, it can still reach a good level.
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Progress of HgCdTe Mercury-Rich Vertical Liquid Phase Epitaxy in 11th Research Institute of CETC
HAO Fei, She Wei-lin, YANG Hai-yan, Hu Yi-lin, Xing Xiao-shuai, YANG Mei-hua, Xing Wei-rong, SUN Hao
Abstract:
In this paper, we focuse on the36mm×42mm mercury-rich vertical liquid phase epitaxy(VLPE) technique. By modifying the structure of the graphite boat carrying the substrates, the batch growth of large-size double heterojunction materials with dimensions of 36mm×42mm has been achieved. By combining the phase diagram of material growth and the calculated fluiddistribution, the fields of fluid and temperature in the growth area of the material are optimized to meet the development requirements of p-on-n infrared focal plane array detectors. The thickness deviation of the grown material and the electrical performance satisfies our expectation. The overall performance of the material meets the requirements for fabricating large-scale, large-format p-on-n infrared focal plane array detectors.
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ZHANG Min, HAN Fang, KANG Jian, SUN Hao, GUO Liang, LI Chun-ling
2019,40(6):35-43
Abstract:
The characteristics of infrared thermal imaging technology are introduced, and the civilian application of infrared thermal imaging technology in civil aviation, electric power, petrochemical, forest fire prevention, medical and other civil fields is discussed. The market situation of infrared thermal imaging technology is introduced, and the development demand of infrared thermal imaging technology in different application fields are analyzed.
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2008,29(8)
Abstract:
介绍了一种利用MATLAB和数值逼近理论计算费米函数的简捷方法.计算结果的误差在10-6数量级,甚至可以更高.与其他方法相比,该方法具有精度高、使用便捷和速度快等优点.
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2008,29(12)
Abstract:
In this paper,the principle and features of four-wave mixing are given.The generation of four-wave mixing is derived in theory and the applications of four-wave mixing in the DWDM for optical fiber communication,phase conjugation wave generation and real time optical detection are given.The study in this paper is aimed at more completely knowing the application direction of the four-wave mixing, a typical nonlinear optical effect and finding more applications for the four-wave mixing by summing up the existing relatively mature applications and research methods.
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Nie Jianhua, Liu Jiaqing, Meng Xin, Han Shunli
2019,40(6):44-48
Abstract:
In order to realize the reasonable classification of optical spectrometers, the classification study is carried out from the working band and spectroscope of the spectrometer. On the basis of in-depth research on the development status of existing spectrometer products at home and abroad, the related research is summarized and analyzed, and the specific classification methods and classification results are given. At the same time, by using known spectrometry technology and the research result, the comparative research conclusions of spectrometers are introduced, and the key technologies and core components are pointed out. This conclusion can provide spectrometer researchers with a panoramic viewing angle and also provide a valuable reference for tracking industry development.
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2010,31(3):42-46
Abstract:
According to the finite difference principle, a one-dimensional Schr\"{o}dinger equation can be converted into a set of nodal linear equations expressed in a matrix equation after the space is divided into a series of discrete nodes with an equal interval. The matrix left division command offered in the MATLAB software can be used to derive the function approximation of each unknown nodal function. This method is simple in concept, convenient in operation and can solve large linear equations without more efforts in programming.
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2008,29(12)
Abstract:
The good properties of THz wave and how to use photoconductive antenna and optical rectification to generate THz wave are described in detail.The applications of THz wave in long distance surveillance,imaging,exploder distinguishing,nondistructive inspection and particularly in the field of military are presented.
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2019,40(7):35-46
Abstract:
The noise sources and denoising methods of functional near-infrared spectroscopy (fNIRS) brain imaging are reviewed. The method and operation of suppressing noise are analyzed and given from the aspects of imaging principle, noise source and occurrence mechanism. The composition and characteristics of the interference are analyzed in detail, the effective removal method is given, and the signal quality algorithm in the process of brain imaging analysis and modeling of near-infrared spectroscopy is improved. These methods can provide guidance for the analysis and processing of near-infrared spectroscopy brain imaging data. Three noise sources that affect near-infrared spectroscopy brain imaging signals are summarized: instrumental noise, experimental error and physiological interference from the body. Two practical denoising algorithms are given and the development trend of imaging technology is expounded.
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GUO Xiao-Dong, ZUO Zhi-Gao, YUE Song, HONG Pu
2019,40(7):18-25
Abstract:
The theoretical model of infrared point target detection system is systematically analyzed. The transmittance of medium-wave and long-wave infrared light under typical atmospheric conditions is calculated by establishing the atmospheric stratification model and combining the MODTRAN model. The comparison data of the two calculation results can provide reference for the band selection in the design of infrared detection system. By analyzing the theoretical model of infrared radiation intensity of targets, the infrared radiation intensity of several typical targets in different wavebands is calculated, which provides support for the demonstration of operation range for IR system. Based on the probability density distribution function of infrared image noise, the theoretical formulas of image signal-to-noise ratio, system detection probability and false alarm probability are derived, which provide reference for setting detection threshold. The theoretical model analysis results of infrared point target detection system''s operation range can offer an important theoretical support for improving the credibility of infrared detection system''s operation range demonstration and the rationality of system parameter design.
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2010,31(3):11-14
Abstract:
The typhoon center is usually located manually by meteorologists. This location method has a low degree of automation. According to the movement characteristics of typhoon and the meteorological analysis theory, a single infrared satellite cloud image is used to establish a method for extracting the dominant cloud movement vectors. On this basis, the optimal target function for locating the typhoon center automatically is set and resolved. The automatical location of the typhoon with an eye or without an eye is realized. The method is used to simulate the automatical location of the center of typhoon ``HAITANG' in several cloud images obtained in 2005. The result shows that this method has a high location accuracy and can be used as a good technical means for the automatical location of typhoon center.
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2019,40(6):27-34
Abstract:
From the perspective of theoretical numerical simulation and near-field radiation experimental research, the latest research results in near-field thermal radiation heat transfer are introduced. The focus of theoretical research is mainly on heat transfer studies in graphene composites, artificial processing and synthetic metamaterials. The focus of experimental research is on laboratory equipment manufacturing and method innovation based on nanoscale near-field thermal radiation measurements. Very near-field thermal radiation measurements with a minimum distance of only 2 nm have been experimentally implemented. Further research on near-field thermal radiation provides a theoretical basis for thermal photovoltaic, radiant cooling and efficient energy harvesting applications.
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wngxinkun, zhaofang, wangjianjiang
2019,40(7):1-11
Abstract:
With the advent of various new types of detection radars, advanced infrared detectors and precision guided weapons, infrared & radar compatible stealth materials have become the focus of current stealth technology research. The stealth principle and research status of traditional and new infrared & radar compatible stealth materials are reviewed, and the development direction of future infrared & radar compatible stealth materials is summarized and forecasted.
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2013,34(7):15-19
Abstract:
Starting from the Schrodinger equation, the influence of different Al composition and different temperatures on the absorption spectra of wide quantum well infrared photodetectors (QWIP) is studied. It is found that when the Fermi level is fixed, the ground state bound energy of the quantum well may increase with the increasing of the Al composition and the corresponding absorption spectral peak tends to move toward the short wave. In addition, the influence of the ambient temperature on the response spectra of AlGaAs/GaAs QWIPs is negligible. After theoretical calculation, the rule of the absorption spectrum of an AlGaAs/GaAs QWIP changing with quantum well width, Al composition and temperature is given.
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2008,29(12)
Abstract:
第一部分 一、探测与识别 1.高光谱图像的结构模型中正交子空间投影探测器与匹配滤光片的分析比较(P.Bajorski,美国罗彻斯特理工学院)
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Gao Yuxuan, Chen Xingming, Dai Jun, Yang Meixia, Huang Shoubin, Chen Xiang, Hou Zhenyan, Huang Jian
2023,44(4):20-32
Abstract:
Focusing is a key part of the launch focusing device in highenergy laser systems, and the focusing mechanism plays an important role in the targeting and striking accuracy of the system. In order to understand the research status and development trend of focusing mechanism, various types of foreign mature focusing mechanisms are introduced firstly. The principle of their focusing control and the solutions of various technical problems are analyzed. The domestic research situation focuses on four types of focusing mechanisms: cam, screw, worm gear and direct drive. For each form of focusing mechanism, the basic principle of controlling focusing is analyzed, and the design features of the focusing mechanism applied to different systems are introduced. By analyzing the design and control of each type of focusing mechanism, the advantages and disadvantages are summarized and compared, and the design ideas and research directions of the focusing mechanism for high-energy laser systems are proposed to lay the technical foundation for the research on focusing mechanism of high-energy laser systems.
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2008,29(8)
Abstract:
本文研究由介电系数和磁导率为负的材料组成的一维光子晶体中的电磁波脉冲的传播特性.利用传输矩阵的方法,计算出了该结构中脉冲传播的透射谱和相时间.数值结果表明,在光子带隙的带边和带底会分别出现脉冲传播速度减慢和加快的现象.若周期结构中间存在缺陷层,光子带隙中会出现极窄的透射峰,因此,对应于该频率的电磁波在该体系中传播时速度会变得更加缓慢.
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PAN Ming-zhong, QI Hong-xing, XIAO Gong-hai, SHU Rong
2010,31(1):1-7
Abstract:
A compact field hyperspectral imaging spectrometer based on a prism-grating-prism structure is presented. The system is designed for the wavelength range from visible light to near infrared. It has 344 spectral bands with the spatial resolution higher than 10 nm and the spectral resolution higher than 1 mrad. To study the unmixing of mixed pixels, the basic principle of the field hyperspectral imaging spectrometer is described, the main specifications of the system is analyzed, the design of the system is discussed in detail and related tests are conducted. The test results show that the system has both higher spatial resolution and higher spectral resolution. Because of its compactness and reliable operation, it is very suitable for field applications. Thus, the feasibility of the use of a compact field hyperspectral imaging spectrometer in the research on the unmixing of mixed pixels is verified.
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2011,32(8):25-28
Abstract:
Sea-sky-line detection can be implemented by effectively suppressing the background and enhancing the target in an image according to the features of sea-sky environment. An improved method for wiping off crass points is proposed on the basis of the linear fitting algorithm. The method is simulated with the Matlab software. The simulation result shows that this improved method can effectively detect the positions of the sea-sky-line and ships against the sea-sky background. It provides a good basis for target recognition and image registration.
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WUWEI, HANSHUNLI, HOUXIBAO, LIULEI, XIANGGUOQING
2017,38(6):1-7
Abstract:
According to the spectral response curves and dark current of a near infrared two-dolor detector in two different operation wavebands, a signal acquisition system based on the near infrared two-color detector is designed. The system has many current-voltage conversion levels, voltage amplification levels and filter circuit bandwidth levels. It can amplify signals and control bandwidth quickly. Moreover, it provides zero analog signals for four amplify circuits via a Digital-to-Analog (D/A) convertor. This can effectively eliminate the noises caused by the stray light and the dark current of the detector itself. The system has the features of high speed, low noise and high resolution. By using this signal acquisition system, many parameters of the optical system, such as signal-to-noise ratio, dynamic range and minimum measurable power, can be improved.
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2016,37(4):27-32
Abstract:
An algorithm combining Light of Sight (LOS) with the OpenGL software interface is proposed. The method uses the depth measuring and occlusion query functions of the OpenGL software interface to determine the effective emission surface in the detection direction and the transfer path of its radiation in mediums. Then, it uses LOS to obtain the radiation characteristics of the target in atmosphere in the detection direction. The simulation result shows that this algorithm is effective and has high computation efficiency.
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BAI Wei, ZHAO Chao, GONG Zhi-hong
2017,38(1):6-11
Abstract:
Combining with the X-ray diffraction technique and the layer-by-layer chemical etch method for peeling damage layers, the depth of the damage layer in InSb crystal introduced by cutting, lapping and polishing was analyzed quantitatively. The structures and causes of damage layers were discussed. The research result showed that cutting was the major process for introducing damage layer on the surface of InSb wafers. The depth of the damage layer introduced by cutting was up to 16 microns. The depth of the damage layer introduced by double-face lapping was about 12 microns. The depth of the damage layer introduced by mechanical-chemical polishing obviously decreased. It was about 2 microns.
