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单位咨询委员会(以下简称CCU)是国际计量局(BIPM)下设的9个咨询委员会之一。CCU成立于1964年,主要负责量和单位问题的研究,提出修改物理量及其单位的值和定义草案,交国际计量委员会(CIPM)审议,使CIPM可直接做出决定,或提出议案交国际计量大会(CGPM)批准,以保证计量单位在全球范围内的统一。2003年4月17日至18日中国代表以客人的身份首次参加了在巴黎国际计量局总部召开的第15届CCU会议。本次会议的目的是讨论修订国际计量局“国际单位制”第七版手册(1998年出版),为第八版的出版做准备。为此,CCU主席Mill根据2002年第14届CCU会… 相似文献
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A method for extending dynamic range of phase diversity (PD) is proposed. The estimating of pupil phase is divided into two steps. Low-order Zernike coefficients of the phase are estimated firstly before all of the Zernike coefficients estimated. The method is based on the assumption that the aberrations of the system are dominated by low order Zernike modes, which is true to most practical situations. The algorithm of Broyden-Fletcher-Goldfarb-Shanno(BFGS) is used in the two steps for optimizing process. Computer simulations are conducted after the theoretical analysis. The result shows that this method can effectively avoid the trap in local minimum during iteration process, and the dynamic range that PD can detect extends from about 2λ to about 4λ. 相似文献
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讨论了可使自适应光学系统的视场角大幅度增加的层析原理.首次提出分区计算子孔径所引起的相位畸变的方案,从而解决了以往文献中独立方程的个数少于未知数个数的困难.对两个变形镜的情况作了进一步的分析. 相似文献
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From the point of view of design requirements, influence of the width of the output image of an imaging subsystem in a tomographic imaging spectrometer, namely width of the slit, the grating and the size of the CCD pixel are analyzed. For the tomographic imaging spectrometry, if the amplification ratio of the imaging subsystem is not high enough to make the whole object to be compressed within the slit, then either the slit width should be increased or the slit width kept unchanged but scanned to receive information of the object. While the width-increase method reduces the spectral resolving power and the SNR; the scanning method reduces the SNR.Analysis of the two cases and computer simulation results are given. 相似文献
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用快速数字相关法实现扩展信标的波前探测 总被引:1,自引:0,他引:1
在对H S探测器成像分析的基础上 ,对非相干、扩展信标情况下的波前探测提出了一种新方法 .该方法通过相关计算测量出图像位移量 ,得到波前斜率差 ,并从理论解释和计算机数值计算两方面进行了论证 .它是一种快速精确的数字算法 ,便于在数字信号处理器等硬件中实现 相似文献
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