激光脉冲波形的精密诊断是大型激光装置运行控制和精密物理实验的前提, 而动态范围的大小是衡量诊断系统的关键指标之一。为了满足高功率激光装置对纳秒级整形激光脉冲对比度控制及精密诊断的需求, 采用双探测器与数字示波器四通道分组并行取样的诊断方法, 通过将整形激光脉冲分解为不同的幅值区域并送入示波器的不同输入通道, 每个通道采用不同的垂直灵敏度档位进行探测, 最后利用共同的时基完成波形的对接重构。研究结果表明, 采用的方法可以实现2 500:1的动态范围, 在偏差为2%的测量精度内, 可以实现对比度高达100:1的多台阶整形脉冲的全波形测量。

The ability of temporal pulse reshaping is an important content in high power laser facility operation and fusion ignition experiment. In order to verify reshaping effect, the diagnostic system was optimized by optical and electrical power splitting, the system detected laser pulse shapes with two high-speed vacuum biplanar photodiodes (VPD), coupled to a four-channels 8 GHz oscilloscope. The effective dynamic range of the diagnostic system for measurement of pulses with high-power contrast was increased by splitting the signal from every VPD evenly into two channels of the oscilloscope with different sensitivity setting, the detected pulse from the four channels was stitched back together to form the complete pulse. The result show that the detector and oscilloscope combination has a 10% to 90% rise time of 60 ps, the diagnostic reaches 2 500:1 dynamic range for contrast ratios up to 100:1 at an within 2% uncertainty.