Ablation of Hard Biological Tissue: Dependence on XeCl Excimer Laser Parameters

We have investigated systematically the dependence of ablation efficency on laser pulse duration, pulse energy, number of applied pulses, and fluence using freshly slaugthered rib bone samples immersed in water. The 308 nm radiation was guided by a tapered quartz fiber. The conically shaped front part reduces the laser fluence and avoids surface damage in the launching section of the optical fiber. Laser lesions were examined by scanning laser and scanning electron microscopy. No carbonisation was observed; the temperature increase of the tissue was below 40°C in the surroundings of the laser spot. Laser pulse duration was increased in steps of 30 ns up to 220 ns.The ablation rate increased linearly with applied pulse energy, but did not depend on the pulse duration.