在超短脉冲激光系统中,像差的存在会使焦斑能量集中度降低。为了克服系统中像差的影响,提高系统最终功率密度,分析了系统中像差的来源,并利用光线追迹方法模拟了系统光路,计算了全系统的像差,提出并设计了双分离透镜作为末级空间滤波器输出透镜进行全系统像差的补偿。实验表明,利用所设计的双分离透镜,可以有效地补偿系统色差和球差,使系统输出焦斑半径从未补偿前的8.6 μm缩小为5.7 μm,而系统的聚焦功率密度提高了8倍,改善了装置性能。

Analysis shows that intensity of the focal spot will be decreased by the systemic optical aberration in a multi-hundred TW ultra-short laser system. In order to increase the intensity of the far-field by avoiding both axial chromatic and spherical aberrations caused by the lens as in the laser system, source of the aberrations was studied, simulation of layout was performed by ray tracing method and air-spaced doublet as the last spatial filter was specially designed to compensate those aberrations. Experimentation proves that the air-spaced doublet can diminish both axial chromatic and spherical aberration of the whole system effectively , the radius of the output focal spot decreases from 8.6 μm to 5.7 μm, and the intensity of the focus increases by eight times.