Efficient and tissue-saving bone ablation with a pulsed 3 µm laser source

Thermo-mechanical hard tissue ablation with pulsed mid-infrared lasers is an efficient and minimally invasive method for precise bone cutting. The efficiency of the ablation process strongly depends on the absorption of laser radiation in the intracellular water of hard tissue. Therefore, 3 µm laser sources show high efficiency in bone ablation with a small heat affected zone. Until now, it was not possible to transfer this high efficiency into high ablation rates because of the limited repetition rate of commercially available laser sources. In this study, we demonstrate ablation experiments on bovine bone tissue utilizing a novel 3 µm laser source with a repetition rate of 12 kHz and nanosecond pulse duration. We optimized process parameters especially focus position, flow rate of a water spray system and pulse overlap for a fast and non-thermal ablation process. By optimizing the optical system, we were able to realize a fluence for fast bone ablation with rates of up to 2.2 mm3/s and a maximum ablation depth of 3.4 mm. For further increase of the depth-dependent ablation rate, it was possible to estimate required beam caustic and laser specifications.