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The dynamic range of a picosecond visible streak camera has been improved by the combination of a plasma shutter and multishot averaging performed with a photoconductive switch sweep circuit. We use this technique to measure the contrast of a 100-fs laser pulse over 2 ns with a dynamic range of 7 orders of magnitude. 相似文献
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A phase-locked terahertz transient is exploited as an ultrafast phase gate for femtosecond optical pulses. We directly map out the group delay dispersion of a low-power near-infrared pulse by measuring the electro-optically induced polarization rotation as a function of wavelength. Our experiment covers the spectral window from 1.0 to 1.4 μm and reaches a temporal precision better than 1 fs. A quantitative analysis of the detector response confirms that this streaking technique requires no reconstruction algorithm and is also well suited for the characterization of pulses spanning more than one optical octave. 相似文献
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E. Man�� J. A. Behr J. Billowes T. Brunner M. Brodeur F. Buchinger J. E. Crawford J. Dilling S. Ettenauer C. D. P. Levy A. Voss M. R. Pearson 《Hyperfine Interactions》2011,199(1-3):357-363
Collinear laser spectroscopy with reverse-extracted cooled bunched beams was performed at TRIUMF with radioactive ion beams. Surface-ionized 78,78mRb ions were injected into TITAN??s cooler-buncher, and reverse-extracted to the laser beam line. There they were neutralised and excited with a counter-propagating laser beam. The fluorescence signal from the D 2 line was recorded with a photomultiplier tube. The cooler provided typically 50 ion bunches per second, with each bunch containing approximately 105 ions, temporally distributed with a 1.6 ??s width. A hardware gate was set on the signal, suppressing the background by four orders of magnitude. 相似文献
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全光固体条纹相机采用空间调制抽运光激发平板波导光偏转器,通过精确控制抽运光和信号光之间的时间延迟,实现对入射到波导芯层信号光的偏转扫描.它能有效解决传统变像管条纹相机因空间电荷效应造成的动态范围降低以及光电阴极材料在红外波段探测受限等问题,且结构简单,系统稳定性高,理论时间分辨率可达皮秒甚至亚皮秒量级.本文围绕全光固体条纹相机的核心部件—–AlxGa1-xAs/GaAs/AlxGa1-xAs平板波导光偏转器,研究了在带填充效应、带隙收缩效应以及自由载流子吸收效应作用下GaAs折射率的变化情况;在GaAs折射率变化达到0.01量级,信号光束斑大小和波导宽度之比p=0.5时,得到系统的理论时间分辨率为2 ps;按照静态实验条件求得的理论空间分辨率为17 lp/mm,实验结果显示其值为9 lp/mm. 相似文献
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It is pointed out that the usual (Gibbs) thermal equilibrium state in Minkowski spacetime is no longer a thermal equilibrium
state for a uniformly accelerated observer. Similarly, the thermal equilibrium state in Kruskal spacetime is not a thermal
state for a Schwarzschild observer. 相似文献
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Incorporating an electro-optic modulator with a conventional optical streak camera extends the spectral range of the streak camera from the optical region (UV, visible, and near-IR) to the terahertz region (far-IR and millimeter-wave) with a minimum modification. We demonstrate the temporal measurement of freely propagating terahertz pulses with single-shot capability. 相似文献
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This paper deals with a theoretical and experimental study of the picosecond synchronization of a streak camera used in conjunction with a cw actively mode-locked laser system. The temporal resolution of two synchronization set-ups, a passive device (sweep obtained directly from the mode-locker oscillator) and an active arrangement (deflection derived from the recurrent laser pulses through a photodiode and a tunnel diode) has been examined. On the basis of the stochastic analysis it has been possible to interpret the experimental results for both configurations: in particular, it has been demonstrated that even in the presence of phase noise in the laser signal, perfect synchronization can be achieved. 相似文献
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The durations of ultra-short (4–7 psec) laser pulses have been directly measured with an image tube streak camera designed for time resolution in the picosecond region. The camera was calibrated with simultaneously recorded two photon fluorescence pulse profiles and it is shown that a time resolution limit of ≈1 psec should be possible with this system. 相似文献
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Aleksander A. Kubicki Piotr Bojarski Marek Grinberg Micha? Sadownik Benedykt Kukliński 《Optics Communications》2006,263(2):275-280
Apparatus to study time-evolution of emission spectra over very wide time and spectral range is described. Excitation part of the equipment consists of solid state Nd:YAG laser and optical parametric generator. The heart of the detection system consists of spectrograph and streak camera. The significance of optics and electronics built in the system for proper, fast and convenient measurements is underlined. The results of donor-acceptor energy transfer in a rigid polyvinyl alcohol matrix serve here as an example of application our equipment to study complex systems. 相似文献
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Streak camera has high temporal resolution and high sensitivity, and is a powerful tool in biomedical study to measure fluorescence lifetime and perform fluorescence lifetime imaging. However, nonuniformity of the gain in the streak tube and nonlinearity of the sweeping speed limit the precision of fluorescence lifetime measurement, particularly when fluorescence lifetimes are short. We have constructed a two-photon excitation fluorescence lifetime measurement system that is based on a synchroscan streak camera and have developed accordingly a method to correct the effect of gain nonuniformity and nonlinearity of sweeping speed on the measurement precision. A continuous-wave laser of high stability is used to calibrate the gain of the streak camera, and a Fabry-Perot etalon is used to calibrate the nonlinearity of the sweeping speed. Fitting algorithms are used to correct the gain of the streak camera and nonlinearity of the sweeping speed respectively, which significantly improves the measurement precision of the system, as characterized through the fluorescence lifetime of the short-lived fluorescence dye, Rose Bengal. Experimental results show that the measurement fluctuation of the lifetime has been improved from more than 10% to 2% after correcting the effects of gain nonuniformity and sweeping speed nonlinearity. 相似文献
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A streak camera driven with picosecond accuracy by a laser-activated cryogenic Si-switch has been used to measure the decay time of malachite green in water by a pulse fluorimetry technique. The single shot timing accuracy of the streak camera (a few ps) corresponds to ~10% of the optical pulsewidth. The overall stability of the system allows the averaging of hundreds of laser shots without image translation improving both the signal to noise ratio and timing accuracy of the measurements.. The subpicosecond timing accuracy afforded by shot averaging has enabled us to measure a 2 ps fluorescence decay time for a low quantum yield sample with a 20 ps excitation pulse. 相似文献
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We present a novel sampling imaging technique capable of performing simultaneous two-dimensional measurements of the temporal and spectral characteristics of light-emission processes by use of a specially designed streak camera. A proof-of-principle experiment was performed with a homemade multifocal multiphoton fluorescence microscope. The system was calibrated with a Fabry-Perot etalon and a standard fluorophore solution (rhodamine 6G in ethanol) and was shown to have temporal and spectral resolution of 6.5 ps and 3 nm, respectively, as well as high accuracy and reproducibility in lifetime and spectrum measurement. Temporally and spectrally resolved images of 4 x 4 foci on the sample can be obtained with a snapshot. 相似文献
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任何热力学量的涨落在平衡态下都不能太大.特别地,要求熵和能量的涨落不大,就可以给出低温下热力学平衡态的普遍适用的判据.一些算例表明,低温下即使1023个粒子也不一定能达到热力学平衡态. 相似文献
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大动态范围长狭缝条纹相机系统 总被引:2,自引:1,他引:2
为了满足ICF实验等离子体诊断需要,研制了一种大动态范围长狭缝软X射线条纹相机系统。该系统在保证30 mm的长狭缝的情况下,通过设计一种短聚焦区高压电子光学系统大大缩短电子的渡越时间、提高阳极工作电压至16.5 kV、弃用MCP内增强器、采用光纤面板耦合和使用制冷CCD等一系列措施,达到改善扫描变像管条纹相机动态范围的目的,同时保证具有较高的时间分辨力。动态测试表明,该系统动态空间分辨力为15 lp/mm,时间分辨力优于31 ps,动态范围大于922。 相似文献
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