飞秒到毫秒激光烧蚀动力学的全息成像
Femtosecond-to-millisecond holographic imaging of laser ablation dynamics
AI总结：
研究飞秒激光烧蚀动力学，引入泵浦 - 探测全息成像方法，能在全时间范围重建光场，应用于BK7玻璃烧蚀，捕捉不同阶段变化，确定能量分配与低热影响加工的关系，为追踪材料转变提供途径。
AI中文摘要：
飞秒激光烧蚀会在从飞秒到毫秒的时间尺度上，将光学沉积能量重新分布到电子、结构、机械和热自由度上。但这些耦合过程通常在不同时间范围通过不同可观测值测量，限制了早期瞬态动力学、残余加热和最终形态之间的定量比较。本文引入泵浦 - 探测全息成像，在匹配成像条件下重建整个时间范围内的幅度和相位分辨光场。应用于BK7玻璃的深紫外飞秒烧蚀时，该方法捕捉了从早期激发和去除阶段动力学到残余衬底加热及永久改性的转变。差分相位分析分离了瞬态烧蚀层的亚纳秒演化和材料去除后的微秒残余加热。结果表明烧蚀阈值以上，坑深随能量密度增加，而残余热信号饱和，确定了能量密度依赖的能量分配是低热影响飞秒加工的动力学基础，并确立全息成像为追踪激光驱动非平衡材料转变的途径。
英文摘要：
Femtosecond laser ablation redistributes optically deposited energy across electronic, structural, mechanical, and thermal degrees of freedom over timescales from femtoseconds to milliseconds. However, these coupled processes are usually measured in separate temporal ranges and through different observables, limiting quantitative comparison between early transient dynamics, residual heating, and final morphology. Here we introduce pump-probe holographic imaging that reconstructs amplitude- and phase-resolved optical fields across this full temporal range under matched imaging conditions. Applied to deep-ultraviolet femtosecond ablation of BK7 glass, the method captures the transition from early excitation and removal-stage dynamics to residual substrate heating and permanent modification. Differential phase analysis isolates sub-nanosecond evolution of the transient ablating layer and microsecond residual heating after material removal. Above the ablation threshold, crater depth increases with fluence, whereas the residual thermal signal saturates, indicating that additional absorbed energy is preferentially partitioned into material removal and ablation-related processes rather than retained as substrate heat. These results identify fluence-dependent energy partitioning as a dynamical basis of low-heat-affected femtosecond processing and establish holographic imaging as a route to tracking laser-driven nonequilibrium material transformations.
