Nuclear and Energy Research Institute, IPEN-CNEN/SP, Av. Prof. Lineu Prestes, 2242, Cidade Universitária, 05508-000, São Paulo, SP, Brazil.
Sci Rep. 2019 Mar 12;9(1):4167. doi: 10.1038/s41598-019-40749-6.
We designed a real time, single-laser focus tracking system using low coherence properties of the machining femtosecond laser itself in order to monitor and correct the sample position relative to the focal plane. Using a Michelson Interferometer, the system collects data arising from part of the beam backscattered at the ablation spot. The data is analyzed by a custom software for position correction (employing an XYZ automated translation stage). With the focus tracking enabled we were able to etch channels with a stable cross-section profile on a bovine tooth with relief amplitude tens of times greater than the Rayleigh length of the system, keeping the sample inside the confocal parameter during most of the processing time. Moreover, the system is also capable of monitoring crater depth evolution during the ablation process, allowing for material removal assessment.
我们设计了一个实时、单激光焦点跟踪系统，利用加工飞秒激光本身的低相干特性，以监测和校正相对于焦平面的样品位置。该系统使用迈克尔逊干涉仪收集来自在烧蚀点处背向散射的部分光束的数据。数据由用于位置校正的定制软件进行分析（采用 XYZ 自动平移台）。启用焦点跟踪后，我们能够在牛牙上刻蚀具有稳定横截面轮廓的通道，其浮雕幅度是系统瑞利长度的数十倍，在大部分加工时间内使样品保持在共焦参数范围内。此外，该系统还能够监测烧蚀过程中的熔坑深度演变，从而实现材料去除评估。
