Abstract Bone drilling is a common surgical procedure of knee arthroplasty, craniotomy, stapedotomy, dental treatment, and laminotomy. Although femtosecond laser processing provides a promising method for precision bone drilling, it is still challenging to achieve thermal accumulation suppression and damage protection for large-scale hole drilling. In this paper, we propose a real-time spectral response guided femtosecond laser bone drilling method with the second-harmonic-generation (SHG) signals for positioning and monitoring. SHG green signal centered at 513.5 nm is generated below laser ablation threshold of bone, which can provide as a label-free detection for initial positioning. Results show that the spectral intensity ratio of green and white signal gradually decreases due to the accelerated removal of hydroxyapatite with the increased laser fluence, while the spectral intensity ratio of red signal and other visible signal can be used to indicate the thermal damage due to the abnormal enhancement of the red signal ranging from 700 to 800 nm when carbonization occurs. Based on the real-time spectral response at different laser fluence, the key laser processing parameters including defocus distance, flow rate of cooling water, and laser fluence are successfully optimized. Finally, a damage-free hole with the average diameter of 3 mm and the depth of 3.6 mm is successfully drilled within 5 min, while the temperature of surrounding hole wall is 37.1 °C. The proposed method provides a direct-viewing, damage-free and high-efficiency way of laser bone drilling with real-time positioning and monitoring.

中文翻译：

---

实时光谱响应引导智能飞秒激光骨钻孔

摘要 骨钻孔是膝关节置换术、开颅术、镫骨切开术、牙科治疗和椎板切开术的常见外科手术。尽管飞秒激光加工为精密骨钻孔提供了一种很有前途的方法，但在大规模钻孔中实现热积聚抑制和损伤保护仍然具有挑战性。在本文中，我们提出了一种实时光谱响应引导飞秒激光骨钻孔方法，利用二次谐波生成 (SHG) 信号进行定位和监测。以 513.5 nm 为中心的 SHG 绿色信号在骨骼的激光消融阈值以下产生，可作为初始定位的无标记检测。结果表明，随着激光能量密度的增加，羟基磷灰石的去除速度加快，绿色和白色信号的光谱强度比逐渐降低，而红色信号和其他可见信号的光谱强度比可用于指示由于羟基磷灰石的热损伤。发生碳化时红色信号异常增强，范围为 700 至 800 nm。基于不同激光注量下的实时光谱响应，成功优化了离焦距离、冷却水流量和激光注量等关键激光加工参数。最后，在5 min内成功钻出一个平均直径为3 mm、深度为3.6 mm的无损伤孔，而孔壁周围温度为37.1 °C。所提出的方法提供了一个直观的、