为了实现调节两束飞秒激光脉冲在时间和空间区域上的精确重合, 采用利用CCD成像系统调节光束在空间上的重合及利用能量计测量激光脉冲核心能量变化来调节飞秒脉冲间的时间间隔的新方法, 取得了核心能量随延迟时间变化的数据, 并记录了相应的等离子体荧光图像。结果表明, 与传统方法相比, 这种方法可以达到飞秒级的时间重合精度。这为确定激光的时空重合提供了一种简便有效的途径, 且在激光光束以大角度相交时仍然可以确定最佳重合点。

To achieve accurate spatio-temporal superposition between two femtosecond laser pulses, a CCD imaging system was used to adjust the spatial superposition of both the beams and an energy meter was applied to measure the core energy of the probe pulses so that the temporal separation between the pulses could be adjusted. The dependence of the core energy on the time delay and the corresponding plasma fluorescence distribution were obtained. The experimental result proves that this method can achieve a higher time accuracy (femtosecond scale) than the traditional method, even when the crossing angle between the two femtosecond laser beams is vertical.