The laser spallation effect due to intense shockwaves caused by a brief and intense laser pulse irradiating a target surface, 2 mm thick, has been investigated for silver and other materials. For 300 ps IR laser pulse, at intensities of the order of 10¹⁶ W/cm², the shockwave may produce deformations of the back-face in ductile materials, such as Ag, Cu and Al. In heavy materials with high tensile strength, such as Ta, the shockwave produces cracks in the bottom of the laser crater but not deformation in the back-face, while in brittle materials, such as monocrystalline Ge, it produces only superficial cracks and flaking, but not deformation and spallation of the back-face. In thick polymeric materials, such as high-density polyethylene, the ablated crater shape is well defined and the shockwave is strongly damped, and no deformation has been observed in the back-face. The laser ablation yield and the ion acceleration in the backward direction have been measured by mass lost and time-of-flight measurements. SEM microscopy of the different irradiated targets, showing details of the crater size, edges, flaking and deformation in the back-face, useful for a discussion on the shockwave propagation and shock pressure calculation, is presented.

中文翻译：

---

1016 W/cm2 强度的亚纳秒激光脉冲对银和其他材料的冲击波和散裂

已经针对银和其他材料研究了由照射 2 毫米厚的目标表面的短暂而强烈的激光脉冲引起的强烈冲击波引起的激光散裂效应。对于 300 ps IR 激光脉冲，强度约为 10 ¹⁶  W/cm ²，冲击波可能会在延展性材料（例如 Ag、Cu 和 Al）中产生背面变形。在具有高抗拉强度的重材料中，如 Ta，冲击波会在激光坑底部产生裂纹，但不会在背面产生变形，而在单晶 Ge 等脆性材料中，它只会产生表面裂纹和剥落，但背面不会变形和剥落。在高密度聚乙烯等厚聚合物材料中，烧蚀坑形状清晰，冲击波受到强烈阻尼，背面未观察到变形。激光烧蚀产率和向后方向的离子加速已经通过质量损失和飞行时间测量来测量。不同辐照目标的 SEM 显微镜，显示了弹坑大小、边缘、