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为了提高激光惯性约束聚变实验二维成像诊断的精密化程度,提出了分幅变像管动态空间分辨率的标定方法.标定原理是以直边函数为物,经光学系统成像后求解系统的调制传递函数,从而获得系统的空间分辨率.在神光II装置上利用八路激光打靶产生1—3.5keV能区的连续X射线标定源,照射高Z刀边材料,并成像到分幅变像管阴极上,分幅变像管采用脉冲选通工作模式获得动态像.对分幅变像管采集的动态图像进行处理得到系统的调制传递函数.根据调制传递函数为0.1时对应的空间截止频率,得到系统的空间分辨率为20lp/mm.根据分幅变像管的动态空间分辨理论,计算系统的极限空间分辨率为22.8lp/mm.标定结果略低于极限空间分辨率,与理论基本吻合.根据传统标定方法得到该分幅变像管的静态空间分辨率为22lp/mm,比动态空间分辨率略高.在二维成像诊断时,分幅变像管工作于动态选通模式,故动态空间分辨率的标定结果更能真实地反映其成像诊断能力.
In order to improve the precision of two-dimensional imaging diagnosis of laser inertial confinement fusion experiment, a calibration method of dynamic image spatial resolution of sub-variable image tube is proposed. The calibration principle is to use the straight-edge function as the object and solve the system modulation Transfer function to obtain the spatial resolution of the system.Using X-ray calibration source of 1-3.5 keV energy range produced by SG laser in SG-II device, illuminate high-Z knife edge material and image it into sub-picture tube On the cathode, the variable image tube adopts the pulse gating working mode to get the dynamic image, and the dynamic transfer function of the system is obtained by processing the dynamic image collected by the variable amplitude image tube.According to the space cutoff frequency corresponding to the modulation transfer function of 0.1, The spatial resolution of the system is 20lp / mm. According to the theory of dynamic spatial resolution of variable image tube, the limit spatial resolution of the system is 22.8lp / mm. The calibration result is slightly lower than the limit spatial resolution, According to the traditional calibration method, the static spatial resolution of the tube is 22lp / mm, which is slightly higher than the dynamic spatial resolution.In the two-dimensional imaging diagnosis, State gating pattern, so the results of the dynamic calibration of the spatial resolution more truly reflect the imaging diagnostic capabilities.