• Volume 28,Issue 3,2009 Table of Contents
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    • STUDY ON THE METHOD OF CORRECTION FOR OCEAN COLOR SENSOR ZERO-VOLTAGE FLUCTATION

      2009, 28(3).

      Abstract (1248) HTML (99) PDF 0.00 Byte (1334) Comment (0) Favorites

      Abstract:The data of an ocean color sensor is abnormal. There are many irregular strips in the retrieved products. Analysis of a large set of data confirms that the data abnormality mainly result from the influence of clamping (zero-voltage fluctuation) on each waveband. Thus, a method named clear water free network adjustment is put forward for repairing the clamping. Then, the clamping repair method is applied to the remote sensing image and the chlorophyll concentration is retrieved from the clamping repaired image. The retrieved products have excellent uniformity and abundant detail. Finally, the comparison between the retrieved and MODIS/Aqua product demonstrates that the clamping repaired signal is getting right, providing a new method for the study on clamping repair and support for the quantitative application of ocean color sensor.

    • NEGATIVE PHOTOVOLTAIC-RESPONSES IN HgCdTe INFRARED PHOTOVOLTAIC DETECTORS IRRADIATED WITH PICOSECOND PULSED LASER

      2009, 28(3).

      Abstract (1228) HTML (118) PDF 424.24 K (2798) Comment (0) Favorites

      Abstract:利用皮秒脉冲激光激发碲镉汞线列探测器上的光敏元,发现光伏响应表现为在最初大约15 ns范围内首先形成一个明显的负光生电压的响应谷,之后才演变为正的光伏响应峰.改变入射激光脉冲的光子能量发现,无论是光子能量大于禁带宽度的单光子吸收跃迁还是小于禁带宽度的双光子吸收跃迁,器件的光伏响应随时间的演变均表现出类似的规律.用光阑对探测器的受光面积进行限制将使负的光生电压减弱并接近消失.结合探测器线列的电极分布构形,将负光伏响应指认为p-电极的肖特基接触所致.利用该方法有可能对p-电极是否形成欧姆接触进行判定,其灵敏度应远高于常规的电学测量方法.

    • Research on short period InAs/GaSb superlattices photoconductors on GaAs substrates

      2009, 28(3).

      Abstract (1962) HTML (126) PDF 385.80 K (2852) Comment (0) Favorites

      Abstract:Two type II superlattices (SLs): InAs(2ML)/GaSb(8ML) and InAs(8ML)/GaSb(8ML) were grown on GaAs substrates by molecular-beam epitaxy. High resolution X-ray diffraction showed the period of the two SLs was 33Å and 56Å. Room-temperature optical transmittance spectra showed clear absorption edge at ~2.1µm and ~5µm for the two SLs. The SWIR and MWIR photoconductor devices were fabricated by standard lithography and etched by tartaric acid solution. The 50% cutoff wavelength of the two photoconductors was 2.1µm and 5.0µm respectively. D*bb was above 5×108 cmHz1/2/W for two kinds of photoconductors at 77K. D*bb was 2×108 cmHz1/2/W for SWIR photoconductor at room temperature.

    • Theoretic analysis and experimental observation for the effect of suspended sediment particle size on remote-sensing reflectance

      2009, 28(3).

      Abstract (952) HTML (89) PDF 532.93 K (2483) Comment (0) Favorites

      Abstract:An experiment was designed and conducted under the stable-controllable conditions in order to minimize the uncertain influences from in situ measurements in the estuarine water. Sediment particles from the Yangtze River estuary and the Yellow River estuary as two typically turbid estuaries in China were sampled in the field, screened and resampled in the laboratory. Furthermore, the quantitative relationships of backscattering coefficient and suspended sediment particle size, and of backscattering coefficient and remote-sensing reflectance were theoretically analysed. The effects of the particle size of sediment on remote-sensing reflectance were experimentally observed. The results provide the basis for the modelling of case-2 waters and the parameterized expression of particle size in the model in future work.

    • Design and Implement of Temperature Controlling System

      2009, 28(3).

      Abstract (904) HTML (97) PDF 501.66 K (3098) Comment (0) Favorites

      Abstract:针对碲镉汞红外焦平面需要在恒定低温条件下工作的要求,设计并实现了基于热电制冷技术的红外焦平面温控系统.该温控系统具有体积小、响应速度快、可控性好及温控精度高等特点,满足设计要求.实验结果表明,该温控系统可使短波红外焦平面在195K时长期稳定工作,温控精度优于0.1℃,焦平面暗电流及噪声水平均有明显改善.

    • TECHNIQUES OF 8mm WAVE BAND SIGNAL DETECTION AND IDENTIFICATION FOR TANK

      2009, 28(3).

      Abstract (1231) HTML (118) PDF 508.73 K (1343) Comment (0) Favorites

      Abstract:研究了坦克装甲目标的毫米波探测识别技术.在比较坦克与主要干扰之间毫米波辐射特性差异的基础上,采用模糊识别方法,以提高识别概率;讨论了毫米波识别中特征参量的选择,提取了109组试验数据的特征参量并对其特征参量矩阵进行数据规格化及加权调整;给出了隶属度函数,计算了试验数据相对于坦克的隶属度.通过分析坦克与干扰的隶属度分布直方图给出了探测概率、虚警率与隶属度门限的关系曲线.

    • TETRAVALENT IONS DOPED LITHIUM NIOBATE CRYSTALS

      2009, 28(3).

      Abstract (1552) HTML (325) PDF 406.99 K (2612) Comment (0) Favorites

      Abstract:The recent progress of HfO2 and ZrO2 doped LiNbO3 crystals was reviewed. LN:Hf crystal has similar optical damage resistance to LN:Mg, but LN:Zr has much better property than LN:Mg. LN:Fe,Hf and LN:Fe,Hf crystals have both fast photorefractive response speed and high saturation diffraction efficiency. And the distribution coefficient of ZrO2 in LiNbO3 is close to one. These results indicate that the tetravalent ions doped LiNbO3 will be the excellent nonlinear optical crystals.

    • Rapid Measurement of Moisture and Calorific Value of Straw by Near Infrared Spectroscopy with LOCAL algorithm

      2009, 28(3).

      Abstract (1079) HTML (130) PDF 426.17 K (2427) Comment (0) Favorites

      Abstract:Moisture and Calorific value, which are two of the most important properties of straw for energy conversion process, were predicted by near infrared spectroscopy (NIRS) technique combining the use of LOCAL algorithm. Firstly the samples were evenly divided into 3 subsets according to the chemical values, named low, mid and high concentration respectively, to build global PLS calibrations. Standard errors of cross validation (SECV) of the three calibrations based on subsets were almost lower than that of calibration based on the whole samples, suggesting that the variation of moisture and calorific value affect the accuracy of NIRS calibrations. Then LOCAL algorithm was introduced to near infrared spectroscopy analysis for rapid measurement of the moisture content and calorific value of straw samples. By the use of LOCAL algorithm, which patented by Shenk to reasonably select a group of samples for each sample to build partial least square regression (PLS) calibration, the prediction accuracy were improved compared to the PLS and MPLS models for both moisture and calorific value of straw. It was therefore concluded that LOCAL algorithm applied in quantitative analysis of straw was able to improve the prediction accuracy.

    • Absolutely radiometric calibration of FY-2C infrared split-window channels using sea buoy data and NCEP reanalysis data

      2009, 28(3).

      Abstract (1970) HTML (119) PDF 638.25 K (3650) Comment (0) Favorites

      Abstract:A method of absolutely radiometric calibration of FY-2C infrared split-window channels using sea buoy data and NCEP reanalysis data was introduced. In 2006, ten times remote sensing data were selected to obtain the radiometric calibration coefficients. The calibration results obtained from this new method were compared with the product brightness temperature look up tables. The results show that the biggest differences between the top of atmosphere (TOA) brightness temperatures inversed from these two suits of calibration coefficients were mainly located on low surface temperature pixels, such as top of clouds and snow covered areas and in normal temperature pixels like land and sea surface areas, the differences were mainly around 2K. This new vicarious calibration method can increase the calibration frequency and provide a methodological foundation for the Real-time radiometric calibration of FY-2C infrared split-window channels.

    • FAILURE AND FEM ANALYSIS OF INDIUM SOLDER-BUMPS OF HgCdTe DETECTORS

      2009, 28(3).

      Abstract (1285) HTML (116) PDF 625.66 K (2765) Comment (0) Favorites

      Abstract:卫星工作时,由斯特林机致冷的HgCdTe中长波红外探测器会经受从-173℃以下到常温的成千上万次温度循环.由于不同材料的热膨胀系数(TEC)不匹配,这样就会造成电极封装的疲劳和失效,进而影响卫星的正常工作.利用中科院上海技术物理研究所研制的温度循环设备TCE-a,模拟了真空环境下的斯特林制冷机的开关机模式,发现了In焊凸点的两种失效模式.运用有限元方法,对In焊凸点的失效进行了力学分析.

    • Full-polarimatric Spectral Characteristics of Chaff Cloud

      2009, 28(3).

      Abstract (1080) HTML (100) PDF 595.32 K (2616) Comment (0) Favorites

      Abstract:Based on the spiral descending model of chaff, the effect of both rotation and translational motion of chaff to radar echo of chaff cloud is studied and the full-polarimetric spectral characteristics of radar echoes from a chaff cloud is investigated using statistical method. Firstly, spiral descending model of chaff is described, and the Sinclair Matrix of a dipole with rotation is given. Based on the above, correlation and cross-correlation functions of the Sinclair Matrix elements are investigated and further power spectrum and cross-power spectrum is derived. At last, some numerical results of radar echo spectral for randomly oriented and horizontally oriented chaff cloud are presented.

    • Design of Infrared Optical System with Special Dome

      2009, 28(3).

      Abstract (1677) HTML (120) PDF 339.73 K (3086) Comment (0) Favorites

      Abstract:The dome on an aircraft is not only for protection, but also a part of the infrared optical system for control and guide. In the past, in order to reduce its impact on the aberration of the imaging system, the traditional dome is designed as a concentric hemisphere. However, when the aircraft flies in a high speed, the problem of air resistance must be taken into account. The hemispheric dome is not the best solution from the aspect of aerodynamic performance of the whole system. Therefore the design of new domes and their associated infrared imaging systems receives special research interest nowadays. This paper presents an efficient approach of designing a special dome and its aberration corrector, using the method of Wassermann-Wolf differential equations to generate the optimum contour of the corrector through a macro in CODE V. This corrector reduces spherical aberration and coma which are introduced by the dome and improves the imaging quality of the system. This paper is based on the Wassermann-Wolf algorithm, aims at the designing of a dome in an infrared system which works in the spectrum of middle infrared with a field of view more than 3.5 and an F number of 1-2.5. It adopts a complex R-C form to make the final imaging quality meet the diffraction limit. The whole system satisfies the imaging requirements in the infrared spectrum, and has a high practical value.

    • Research on Identification of Species of Fruit Trees using the spectral reflectance of canopies of fruit trees during flowering period

      2009, 28(3).

      Abstract (1149) HTML (120) PDF 496.33 K (2935) Comment (0) Favorites

      Abstract:利用冠层光谱反射率数据(Rλ),对处于开花期的7种果树的树种进行了辨识研究.通过光谱数据重采样、植被指数求算等相关数据处理,比较了6种卫星传感器与4种植被指数对果树树种的辨识效能,并在优选数据形式、优化模型参数的基础上,建立了辨识果树树种的BP神经网络模型.主要结论为:(1)6种卫星传感器辨识果树树种的效能由强到弱的排列顺序为:MODIS、ETM+、QUICKBIRD、IKONOS、HRG、ASTER;(2)在4种植被指数中,RVI对果树树种的辨识效能最强,其次是NDVI,SAVI与DVI的辨识效能相对较弱;(3)用MODIS或ETM+传感器的近红外通道与蓝光通道上的反射率数据,求算的RVI与NDVI对果树树种的辨识效能相对较强;(4)在Rλ及其22种变换数据中,波长间隔设为9nm的d1[log(1/Rλ)],是建立BP神经网络模型的首选数据形式.

    • SAR IMAGE DESPECKLING BASED ON ADAPTIVE WINDOW AND SHAPE ADAPTIVE - DISCRETE WAVELET TRANSFORM

      2009, 28(3).

      Abstract (1810) HTML (112) PDF 501.93 K (3964) Comment (0) Favorites

      Abstract:Considering the prior knowledge of SAR image in spatial domain and the property of coefficients in wavelet domain, this paper presents a novel algorithm of SAR image despeckling: constructing an adaptive window and finding a uniform region for every pixel of SAR image by using Local Polynomial Approximation-Intersection of Confidence Intervals (LPA-ICI), implementing hard-threshold shrinkage with fast shape adaptive discrete wavelet transform proposed in this paper. At last, many despeckled samples are fused into a final despeckled SAR image according to the sparsity of regions, which is presented in this paper. Experiments show that the algorithm proposed in this paper has advanced despeckled performance. Especially, reconstructed image is absent from unpleasant ringing artifacts, and efficiently reserves point targets of original SAR image.

    • The Research of Infrared Imaging Simulation for Midcourse Ballistic Object Target Complex

      2009, 28(3).

      Abstract (1636) HTML (120) PDF 533.50 K (3199) Comment (0) Favorites

      Abstract:The simplified radiance model of midcourse ballistic target, and the infrared focal plane model based on point spread function and target tail, were presented. Integrating the calculations for target space position and the position in 2D focal plane projected from 3D space, the imaging of midcourse ballistic object target complex in space-based infrared sensor were simulated. With the analyses to the simulation results, it is confirmed that the midcourse ballistic object target complex gives rise to new challenges for detection and tracking techniques of space-based infrared sensor. The methods meeting these challenges were afforded.

    • Multi-Wavelength Laser Atmospheric Extinction Correlativity and Real-time Inversion Computation Study

      2009, 28(3).

      Abstract (1657) HTML (131) PDF 462.68 K (3703) Comment (0) Favorites

      Abstract:The correlativity of extinction coefficients at different wavelengths was get by Mie scattering theory and the laser multipoint fault measuring techniques. The extinction coefficient at the wavelength of 1.06um was measured with the laser remote sensing back scattering hazemeter produced by ourselves. Then the extinction coefficients at the wavelength of 0.532um, 0.86um, 1.57um and 3.47um were inversely calculated real-timely with the correlativity of extinction coefficients at different wavelengths and were compared with the practical extinction coefficient at the wavelength of 0.532um. The results showed that it is feasible to inversely calculate the infrared atmospheric propagation and establish the infrared radiation real-time atmospheric propagation correcting model with the correlativity of extinction coefficients at different wavelengths.

    • Chirped AM and near infrared synthetic aperture ladar range dimension processing

      2009, 28(3).

      Abstract (1198) HTML (113) PDF 515.72 K (3386) Comment (0) Favorites

      Abstract:Synthetic aperture ladar is a coherent imaging ladar which uses relative motion of aperture to the target and signal processing to simulate apertures array to obtain high transverse resolution. Narrow line width single frequency fiber laser sour and coherent detection is employed; transmitted optical wave is modulated with chirped signal on amplitude, the received signal is compressed on length. Relative motion between ladar and target changes the phase of echo . Phase compensation and integration by correlation operation increases azimuth resolution. We bring forward a new work style: chirped signal on range dimension was modulated on optical signal amplitude, Doppler frequency shift on azimuth dimension changes optical wave phase (frequency) of echo , which is convenient for resolving coupling hazy problem between range and azimuth dimension. We report part experiment result : laser intensity was modulated with chirp RF, then range dimension compress for synthetic aperture ladar was realized.

    • Infrared small target detection using TDLMS based on neighborhood analysis

      2009, 28(3).

      Abstract (1850) HTML (163) PDF 542.19 K (4294) Comment (0) Favorites

      Abstract:TDLMS filter can be used for small target detection. However, the limitation of the structure of the filter and algorithm has created some difficulties in the detection. This paper proposed a TDLMS filter based on neighborhood analysis which improves the structure of the input window and incorporates new data processing blocks, enabling more information around the target taken into consideration. Experimental results showed the effectiveness of the proposed algorithm in detecting targets.

Editor in chief:Jun-Hao CHU

International standard number:ISSN 1001-9014

Unified domestic issue:CN 31-1577

Domestic postal code:4-335

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