Picosecond X-ray plasma radiation measurements

Direct picosecond measurements of X-ray laser plasma radiation were performed with a high-speed X-ray image-converter camera (ICC). This camera operates in the single-frame mode with an exposure time ranging from 5 ns to 0.5 μs and in the streak mode with 5 × 10⁹ to 5 × 10⁷ cm/s streak velocities. Its temporal resolution in the streak mode was calculated to be about 7 ps. A plasma was created by focussing 10 ps 1 to 2 joule laser pulses onto a titanium target placed in a vacuum chamber. The halfwidth of the recorded X-ray pulses varied from 30 to 60 ps.     

一种长狭缝软X射线扫描相机系统

 介绍了一种长狭缝软X射线扫描相机系统。其有效工作面积达0.1mm×30mm，以满足宽频谱记录要求，通过优化变像管电子光学系统设计，尽可能地减小了时间畸变；提出利用计算机软件对残存时间畸变进行高精度校正的方法。动态测试表明，在2.5cm/ns的扫描速度下，其动态空间分辨率优于15Lp/mm，时间分辨率优于5ps。     

用于双光子激发荧光寿命显微成像的高重复频率皮秒扫描相机

建立了一台基于新研制的高重复频率皮秒扫描相机的双光子激发荧光寿命显微成像系统,重点介绍所研制的高重复频率皮秒扫描相机。为了在高时间分辨力的同时扩大时间测量范围,实现大面积两维空间高时间分辨取样测量,从而提高采样速率和更有效地发挥扫描相机的作用,设计和研制了一种大面积、高时间分辨力扫描变像管和一种重复频率高达1MHz的斜坡电压扫描电路。基于上述关键部件所研制的扫描相机具有重复频率高、扫描速度可调、时间分辨力高、工作面积大、非线性低、触发晃动小等优点。用钛宝石飞秒激光器作为激光脉冲源,通过脉冲提取器将76MHz的高重复频率降低为1MHz,采用可调延时器和标准具对扫描相机的时间分辨力、扫描速度和非线性进行标定。该系统的时间分辨力达到6.5ps,非线性为2.60%,可测量的时间范围从十几皮秒到几十纳秒。测量了若丹明6G和香豆素314两种标准荧光染料的荧光寿命,取得了与参考文献一致的实验结果。     

A Soft X-ray Streak Camera with Slit Length of 30 mm

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X光条纹相机时间性能标定

 X光条纹相机在惯性约束聚变实验诊断中具有重要作用,它的性能技术指标的精确标定是实验数据可信度的基础。在上海激光联合实验室的20 TW激光器上对X光条纹相机的扫速、时间分辨等时间性能进行了标定,取得了较好的结果。标定结果显示相机的各项性能与出厂标称值有了较大改变。标定的实验结果可有效提高ICF实验数据处理和物理分析的可靠性。     

A ∼20 ps resolution crystal streak camera

This paper describes the design and performance of a streak camera based on a LiNbO₃ electro-optic deflector. The camera has a total sweep time of ～4 ns and a temporal resolution of ～20 ps for ～0.5 μm radiation. Operation between ～0.35 μm and ～5.2 μm with either coherent or incoherent light is possible. Consequently the camera has many potential applications in the field of picosecond optical chronoscopy.     

A simple jitter-free picosecond streak camera

Using a DC-biased room-temperature photoconductive switching element, a picosecond resolution optical streak camera is operated at sweep rates up to 7 ps/mm. Single-shot jitter is 2 ps with complete absence of short and long-term drift characteristic of all other sweep drivers. This high accuracy allows the streak camera to be used in a single-shot averaging mode which leads to a sub-picosecond absolute timing accuracy. When operated in this manner, the streak camera becomes a highly reliable and accurate device for measuring transient events on a time scale of single picoseconds. The simplicity of this method makes it highly attractive for many applications in laser fusion and picosecond chemistry and photophysics studies where reliable no-drift operation is highly desirable.     

高压功率晶体管在扫描相机中的应用

本文讨论了使用高压功率晶体管作为开关器件研制的扫描电路,并在变象管扫描相机中应用,获得了良好的结果,大大提高了扫描电路的耐大电流冲击性,提高了相机的可靠性与稳定性,最高扫速可达10mm/ns,扫描非线性最大为3%,触发晃动为±30ps.工作频率高达20kHz.     

A pulse-train laser driven XUV source for picosecond pump–probe experiments in the water window

We describe the development of a table top soft X-ray source based on a laser produced plasma. The plasma is produced by a Nd:YLF pulse-train laser which delivers pulse trains of up to 400 pulses each of about 25 ps duration. Number and energy of the micropulses are fully computer controlled adjustable for an optimum interaction with a rotating solid target. Spectral, spatial and temporal characteristics of the X-ray emission from Mylar and copper targets have been studied. A calibrated back-illuminated CCD camera together with a slit grating spectrograph were utilized for the measurement of the absolute soft X-ray photon fluxes. The temporal measurements were performed using a streak camera while the plasma size was measured with a zone plate. An application of the system in a X-ray absorption experiment is shown. The advantages of the system in view of possible optical pump and soft X-ray probe experiments will be discussed.     

Simultaneous autocorrelation and synchroscan streak camera measurement of cavity length detuning effects in a synchronously pumped cw dye laser

The cavity matching condition for optimum stable, picosecond pulse generation in a synchronously pumped c.w. mode locked dye laser has been achieved with an accuracy of 2 μm using a synchronously operated streak camera exhibiting a modest temporal resolution of 9 ps. This was possible because of the observed distinct asymmetry of the pulses generated under conditions of cavity mismatch about the zero position. Simultaneous autocorrelation measurements confirmed the streak camera observations.     

一种用于Z箍缩实验的软X射线成像系统

基于塑料闪烁体转换和光学条纹相机的方法建立了一套用于Z箍缩实验中的软X射线条纹图像诊断系统,解决了以往实验中使用的X射线条纹相机易被电磁环境干扰以及相机电极部件易被实验产生的高速粒子损伤的问题.诊断系统的光谱响应范围主要集中在0.2—10 keV,系统的空间分辨率经过理论评估小于120μm,通过标定闪烁体对X射线的时间...     

高重复频率触发模式皮秒扫描相机

讨论了高重复频率扫描电路的研制,利用此扫描电路研制了扫描相机,使用掺钛兰宝石激光器进行了时间分辨率的标定,使用半导体激光器作为光源进行了脉冲宽度的测试.最高工作频率为：1 MHz,时间分辨率为：1.8 ps.     

扫描相机标定脉冲信号位置的确定及噪声处理

 扫描相机标定数据处理中的一个关键问题是如何准确确定脉冲信号的位置,实验数据的信噪比和脉冲信号位置的定义方法都会对标定结果的准确性产生影响。采用了取半高宽的方法来确定扫描相机标定脉冲信号的位置,在信噪比比较高 （大于100） 的情况下,该方法确定标定信号的位置可以达到亚像素水平。对于信噪比比较低 (小于10) 的实验数据,先采用快速傅里叶变换方法对其进行滤波,通过滤波可以极大地抑制噪声信号的影响,然后采用“半高宽法”确定脉冲信号的位置,最后得出可信的标定结果。当扫描相机定在0.3 ns的扫描档时,通过该方法得到的扫描速度为0.214 ps/pixel,扫描不确定度为0.002 9 ps/pixel,拟合线性相关系数为0.999 7。     

亚仟X光扫描相机性能研究

本文介绍了亚仟X光扫描相机的工作原理和实验方法,测定并研究了相机的静态狭缝展宽、触发延迟时间、触发晃动、动态空间分辨率、扫速与非线性、动态范围、时间分辨率。     

X射线皮秒变象管扫描相机时空分辨率测量

X射线皮秒变象管扫描相机是一种应用变象管技术测量X射线波段脉冲辐射而能达到皮秒级时间分辨率和微米级空间分辨率的时空测试系统,是高功率激光打靶产生等离子体诊断的有力工具。时间分辨率和空间分辨率是X射线皮秒变象管扫描相机最基本的性能参数。这些参数的测量有其不同于可见光扫描相机的特殊性。     

一种新型可见光条纹相机标定系统

本文提出了一个以亚皮秒脉冲光源——半导体激光二极管为核心而研究的一台扫描相机标定系统,该系统能对相机的时间分辨率、扫描速度、扫描线性、触发晃动以及相机的最小探测能量等参数进行标定。     

Ultrafast x-ray diffraction using a streak-camera detector in averaging mode

We demonstrate an apparatus for measuring time-dependent x-ray diffraction. X-ray pulses from a synchrotron are diffracted by a pair of Si(111) crystals and detected with an x-ray streak camera that has single-shot resolution of better than 1 ps. The streak camera is driven by a photoconductive switch, which is triggered by 100-fs laser pulses at a repetition rate of 1 kHz. The laser and the streak camera are synchronized with the synchrotron pulses. In the averaging mode, trigger jitter results in 2-ps temporal resolution. We measured the duration of 5-keV pulses from the Advanced Light Source synchrotron to be 70ps.     

Spectral and temporal study of picosecond-pulse propagation in a single-mode optical fibre

The power-dependent pulsewidth variations for input 85 ps pulses from a cw mode-locked Nd: YAG laser propagating through 125 m of single-mode optical fibre have been examined using a Synchroscan streak camera. Simultaneous spectral and temporal measurements provide information as to the optimum parameters for pulse compression in fibres.     

Ultrafast, jitter-free x-ray streak camera that uses single-photon counting

A novel method developed to increase the temporal resolution of x-ray streak cameras is described. The method is analogous to the time-correlated single-photon-counting technique, which is commonly used in atomic physics. By use of short-pulse x-ray radiation from a laser-produced plasma, generated by an ultrafast laser, it is shown that a standard x-ray streak camera with a nominal temporal resolution of >5ps can yield a temporal response of 1.6 ps. The readout technique also removes temporal jitter with respect to the triggering laser. Capabilities and limitations of the technology are discussed.     

神光Ⅲ主机X射线条纹相机设计

根据神光Ⅲ激光器的运作方式和靶室结构,配套建设的X射线条纹相机在结构和性能上同以往有很大不同,建成后不仅应用于高时间分辨的实验诊断,也将用于神光Ⅲ主机各束激光同步性能的检验.设计的X射线条纹相机将全部采用模块化组件,拥有优于10 ps的时间分辨、15 lp/mm以上的空间分辨以及100 eV-10 keY能区的光阴极响应.相机在结构方面采用了非常独特的密闭气室结构,变像管、CCD,所有的电气控制设备都寄宿在气室内并保持常温和一个大气压的工作状态.整个相机系统内嵌了计算机工控设备,通过一根以太网线获得相机所有功能的远程控制.相机其它的特性还包括拥有完善的安全互锁系统以确保相机远程控制的安全;满足严格的EMI/EMP屏蔽要求以避免神光Ⅲ主机高能量激光发射带来的电磁干扰,并可采用光纤引入紫外时标光建立信号的绝对时间基准.