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1.
星载激光测高仪海洋表面回波计算的理论模型   总被引:1,自引:0,他引:1  
马跃  李松  周辉  郑国兴 《中国激光》2012,39(12):1214005-231
不同地表目标的模拟回波波形对测高仪系统参数设计具有重要意义,而海洋回波参数在Tsai之后很少被研究。根据菲涅耳衍射理论、海洋表面镜面反射性质以及海洋表面波高和斜率的统计规律,推导出与Tsai结果不同的近天顶方向入射时星载海洋测高仪探测器输出的回波解析表达式和回波总光子数;并用该推导结果建立了适用于激光测高仪亚毫弧度量级发散角的回波解析式。将模拟波形与地球科学激光测高系统(GLAS)真实海洋回波做对比,其能量、脉宽、振幅和形状都非常接近,误差均小于6%;分析得出海洋测高仪回波与测高系统参数和海平面上方平均风速有关,以GLAS参数为例,在风速大于12m/s的条件下将很难收到有效海洋回波。该结论对海洋激光测高仪的系统设计参数及海平面上方风速的反演提供了重要的理论依据。  相似文献   

2.
朱天豪  周辉  石岩  张千胤 《红外与激光工程》2022,51(1):20210836-1-20210836-11
全波形星载激光测高仪的接收波形特征参数可以用于反演目标的形貌信息,传统的波形处理算法不能用于混叠严重以及偏离高斯形态的多模式波形特征参数提取。针对混叠严重的多模式回波,提出一种基于偏正态拟合模型,使用激励Richardson-Lucy反卷积算法、逐层分解算法、梯度下降法和非线性最小二乘拟合算法相组合的波形特征参数提取方法。采用已知参数的波形数据集、机载仿真波形数据集和全球生态系统动态调查(GEDI)激光雷达波形数据,基于波形相关系数与均方根误差(RMSE)、波形特征参数相对误差、波形分量个数提取正确率等评价指标开展波形处理试验,并将处理结果与传统的高斯分解结果进行比较分析。已知参数波形数据集处理结果的平均波形相关系数提升了约2%,RMSE降低了约47%,波形特征参数相对误差平均降低了约5%,分量个数提取正确率提升了约34%;机载仿真数据和GEDI波形数据处理结果的平均波形相关系数分别提升了约1%和2%,RMSE分别降低了约56%和54%。同时,开展了陡坡区域植被高度解算的仿真试验,得到的植被高度准确程度明显高于传统方法。所有处理结果均表明该方法更有利于多模式回波特征参数的提取以及目标参数的反演。  相似文献   

3.
用机载激光测高仪对单木树冠进行自动提取和轮廓描绘,是获取森林信息的一种快速有效的方法.机载激光测高仪可通过记录回波波形来描绘单树植被冠盖等细节信息,但由于激光足印较小,很难给出树木种群的细节尺度参数,如树的冠盖大小、树径等.提出把若干小激光足印复合成大激光足印的方法,并通过高斯分解算法导出植被冠层高度、植被冠层反射率和...  相似文献   

4.
激光测高仪依靠回波信号包含的信息来反演地面目标的物理特性,因此必须保持回波信号的保真度和高信噪比.通过选择合适的探测器、设计与探测器匹配的放大电路、设计可以最大信噪比提取信号并保持滤波信号波形的滤波器来达到系统指标.讨论了激光测高仪前置放大电路的设计原则,分析了测高系统中对放大器选择的要求.实验表明,所设计的前置放大电路可以有效地满足设计要求.  相似文献   

5.
激光测高仪高斯回波分解算法   总被引:1,自引:0,他引:1       下载免费PDF全文
地球表面地形的复杂多样可对激光测高仪回波波形产生显著影响,造成多峰叠加形状,该波形通过经典的阈值比较或重心点等算法很难精确得到激光足印内每个反射面的海拔高度。通过高斯分解法把测高回波波形分解成一系列连续的高斯波形,通过拟合得到每个高斯波形的宽度、中心点、幅度等基本参数来估计激光足印内起伏地形的不同反射面的海拔高度。将该算法应用于激光测高仪原理样机,并通过采集不同地形的多模回波数据对该算法进行了验证。  相似文献   

6.
星载激光测高仪通过提取激光回波参数计算卫星与地表的距离,结合轨道和姿态信息生成激光脚点的三维坐标。普通高斯光束的空间能量分布随光斑半径增加迅速衰减,不利于探测复杂和分层的地表目标,而平顶高斯光束可以克服这一缺点。根据平顶高斯光束和激光测高回波的相关理论推导得出平顶高斯激光模式下回波波形主要参数的解析式,并使用波形模拟器、波形处理算法,以及地球科学激光测高系统(GLAS)真实回波对所得理论模型进行了验证,结果显示不同阶数激光脉冲的对比偏差都小于3%,且随着目标斜率或阶数的增加,回波宽度和距离误差也随之增加,4阶平顶高斯光束目标斜率0.05时对应的距离误差超过10 cm。  相似文献   

7.
褚喆 《激光与红外》2021,51(5):584-591
为了提高星载激光测高仪估算森林植被高度的精度,本文在处理星载激光森林地区回波波形时,提出了一种基于高斯混合函数模型的波形分解方法,充分保留了波形中有效峰值信息,提高了利用波形估算植被高度的精度。本文以GLAS过中国长白山地区的20个激光点为例,先后进行了自适应波形背景噪声滤除与高斯平滑滤波的波形预处理,对预处理后波形进行了高斯混合函数模型的波形分解,并利用分解后得到的首末子波形估算出激光光斑内的植被高度,对比该光斑样地实测植被高度,结果表明本文估算的植被高度精度为(0.3±1.4)m,其精度明显高于已有的相关算法,故该方法可用于已在轨的高分七号星载激光估算森林植被高度。  相似文献   

8.
利用自适应滤波星载激光测高仪回波噪声抑制方法   总被引:1,自引:0,他引:1  
具有波形记录功能的星载激光测高仪,通过回波信息解算地表与卫星平台距离和反演地物特性。目前广泛采用的固定宽度高斯滤波方法在抑制回波噪声过程中造成有效信号变形,对提取信号有效参量造成严重干扰。根据分块信号统计特性不同的规律,提出了激光测高仪回波噪声均值和方差的估计方法;根据回波信号的统计特性,设计了一种宽度自适应的高斯滤波器。通过GLAS系统实测回波信号的噪声估计与自适应高斯滤波、高斯拟合,得到的波形处理结果与GLAS官方数据有很好的吻合度,噪声均值估计误差小于0.4个数字化仪单位,有效高斯参数计算误差小于1%。该方法能准确地提取波形参量,为地表高程解算和目标表面信息反演提供有效数据。  相似文献   

9.
地形地物对星载激光测高仪回波信号的影响   总被引:2,自引:0,他引:2  
地形地物的回波信号特性影响着星载激光测高仪测量精度。对星载激光测高仪回波脉冲信号进行了理论分析,建立了地形地物数学物理模型,对不同地形地物的回波信号进行了数值模拟研究;在采用不同回波信号检测的情况下,分析了不同地形地物造成回波信号的变化所引起的测量误差。研究结果对保证星载激光测高仪测量精度具有重要的意义。  相似文献   

10.
谢俊峰  杨晨晨  梅永康  韩保民 《红外与激光工程》2020,49(11):20200245-1-20200245-7
全波形激光雷达的回波中包含着地物目标的垂直结构特征信息,传统的全波形数据处理方法在提取这些信息时过于依赖初始参数,导致地形复杂地区的数据可利用率低、准确率低。针对这一问题,提出了一种基于遗传算法的波形分解方法。改进后的处理算法无需提供精确的初始参数,用概率性传递规则代替确定性规则,具有全局寻优特点。并以高分七号卫星激光全波形数据进行试验。结果证明,基于改进后的波形处理方法拟合的回波波形与预处理后波形的相关系数在99%以上。文中对森林地区最大树高的反演与ICESat-2的ATL08产品中的森林冠层高度参数进行对比,两者相关系数为0.85,中误差为1.1 m,表明该方法可以较准确地提取复杂波形的特征信息。  相似文献   

11.
DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.  相似文献   

12.
This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel's.  相似文献   

13.
The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.  相似文献   

14.
Today, micro-system technology and the development of new MEMS (Micro-Electro-Mechanical Systems) are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.  相似文献   

15.
The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.  相似文献   

16.
From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.  相似文献   

17.
Waveguide multilayer optical card (WMOC) is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling & processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic (VB) language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.  相似文献   

18.
It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output(MIMO) communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.  相似文献   

19.
The effect of laser microbeam trapping the bioparticles has been appfied widely in the biology .However the micromechanism of the acting that realizes the laser-microbeam trapping bioparticles is still lacking. In this paper ,the act microchenism of the gradiant force of laser microbeam for the bioparticles is analysed by means of quantum theory ,The result accords with our experiment.  相似文献   

20.
In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal (200) (2d = 0.4027 nm) is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line(w), the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line(x), the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines(y), the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line(z) in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line(q) in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution(λ/△ 2) is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.  相似文献   

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