简介:为了探索大随机相位误差条件下合成孔径雷达(SAL)成像特点和规律,本文采用波长为1550nm的线性调频激光器建立了能够产生大的共模随机相位误差的条带模式SAL成像实验装置。利用此装置获得了不同目标回波强度下条带模式SAL成像实验数据,结合条带模式相位梯度自聚焦(PGA)多次迭代处理,获得了高分辨率SAL图像。实验发现在[-6.45π,6.45π]范围的大随机相位误差下,通过简单的距离压缩和方位匹配滤波,无法实现SAL图像聚焦,图像信噪比仅为3dB。进一步采用PGA处理,就能很好地校正相位误差,得到聚焦良好的SAL图像,图像信噪比达到43dB。实验还发现,当存在大共模随机相位误差时,PGA处理展现出非常强的鲁棒性,在回波弱到10-15W的情况下依然有效。在大相位误差存在的SAL系统(如机载SAL)中,PGA处理能有效消除相位误差,实现图像聚焦;另外,增大探测激光功率以提高成像数据信噪比,将有助于提升PGA处理效果。
简介:Temperatureanddensityasymmetrydiagnosisiscriticaltoadvanceinertialconfinementfusion(ICF)science.Amultimonochromaticx-rayimager,MMI,recordsthespectralsignaturefromanICFimplosioncorewithtimeresolution,2Dspatialresolutionandspectralresolution.Whilenarrow-bandimagesand2Dspace-resolvedspectrafromtheMMIdataconstrainthetemperatureandthedensityspatialstructureofthecore,theaccuracyoftheimagesandthespectrahighlydependsonthequalityoftheMMIdataandtheprocessingtools.Here,wesyntheticallyinvestigatethecriterionforreliableMMIdiagnosticsanditseffectsontheaccuracyofthereconstructedimages.Thepinholearraytiltdeterminestheobjectspatialsamplingefficiencyandtheminimumreconstructionwidth,w.Whenthespectralwidthassociatedwithwissignificantlynarrowerthanthespectrallinewidth,thelineimagesreconstructedfromtheMMIdatabecomereliable.TheMMIsetuphastobeoptimizedforeveryapplicationtomeetthiscriterionforreliableICFdiagnostics.
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简介:Magnetoplasmonicsensorsareattractivecandidatesforultrasensitivechemicalandbiomedicalsensorapplications.Avarietyofferromagneticmetalthinfilmshavebeenusedformagnetoplasmonicdeviceapplications,yetthedependenceofsensorperformanceontheopticalandmagneto-opticalpropertiesofferromagneticmetalmaterialshasbeenrarelystudied.Inthiswork,wereportthestudyofenhancedmagneto-opticalKerreffect(MOKE)andsensingperformanceinAu∕FexCo1-xbilayermagneto-opticalsurfaceplasmonresonance(MOSPR)transducers.TheopticalconstantsofFexCo1-x(x=0,0.29,0.47,0.65,and1)inasputter-depositedAu∕FexCo1-xdevicearecharacterizedbytheattenuatedtotalinternalreflection(ATR)method.FexCo1-xthinfilmsshowdifferentMOKEsasafunctionofthechemicalconcentration,withthehighesttransverseMOKEsignalobservedinFe0.7Co0.3.Indexsensingperformanceiscloselyrelatedtothematerial’sopticalandmagneto-opticalconstants.BystudyingthesensingperformanceintheparameterspaceoftheAu∕FexCo1-xbilayerthicknesses,thehighestsensitivityisfoundtobe0.385(theoretical)and0.306RIU-1(experimental)intheAu∕Fe0.7Co0.3MOSPRdevices.OurresearchhighlightstheinfluenceoftheopticalpropertiesofferromagneticmaterialtodevicesensitivityinMOSPRtransducers.ThehighsensitivityinAu∕FexCo1-xMOSPRdevicesmakethesestructuresattractivecandidatesforchemicalandbiomedicalsensingapplications.
简介:采用闪烁体加光电管,建立了一套X射线功率谱测量系统,在“强光”1号丝阵Z-pinch实验中,获取了喷气和丝阵负载的X光辐射功率波形。实验表明将X光探测器设置在与主测量管道成90°的分测量管道中,并选用ST-401闪烁体或红光闪烁体为X光/荧光转换材料,能使可见光透过闪烁体而不在闪烁体中有沉积能量。实验中X光探测器的电磁屏蔽也得到了解决。