title: Laser cutting of bone tissue under bulk water with a pulsed ps-laser at 532 nm.
abstract: Hard-tissue ablation was already investigated for a broad variety of pulsed laser systems, which cover almost the entire range of available wavelengths and pulse parameters. Most effective in hard-tissue ablation are Er:YAG and CO2 lasers, both utilizing the effect of absorption of infrared wavelengths by water and so-called explosive vaporization, when a thin water film or water–air spray is supplied. The typical flow rates and the water layer thicknesses are too low for surgical applications where bleeding occurs and wound flushing is necessary. We studied a 20 W ps-laser with 532 nm wavelength and a pulse energy of 1 mJ to effectively ablate bones that are submerged 14 mm under water. For these laser parameters, the plasma-mediated ablation mechanism is dominant. Simulations based on the blow-off model predict the cut depth and cross-sectional shape of the incision. The model is modified considering the cross section of the Gaussian beam, the incident angle, and reflections. The ablation rate amounts to 0.2  mm3/s, corresponding to an increase by at least 50% of the highest values published so far for ultrashort laser ablation of hard tissue.
authors.affiliation: Fraunhofer Institute for Laser Technology ILT, Steinbachstraße 15, Aachen 52074, Germany.
authors.forename: Cristian-Alexander
authors.initials: CA
authors.lastname: Tulea
authors.affiliation: Fraunhofer Institute for Laser Technology ILT, Steinbachstraße 15, Aachen 52074, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Caron
authors.affiliation: Fraunhofer Institute for Laser Technology ILT, Steinbachstraße 15, Aachen 52074, Germany.
authors.forename: Nils
authors.initials: N
authors.lastname: Gehlich
authors.affiliation: Fraunhofer Institute for Laser Technology ILT, Steinbachstraße 15, Aachen 52074, Germany.
authors.forename: Achim
authors.initials: A
authors.lastname: Lenenbach
authors.affiliation: Fraunhofer Institute for Laser Technology ILT, Steinbachstraße 15, Aachen 52074, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Noll
authors.affiliation: Fraunhofer Institute for Laser Technology ILT, Steinbachstraße 15, Aachen 52074, GermanybRWTH Aachen University, Chair for Technology of Optical Systems, Steinbachstraße 15, Aachen 52074, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Loosen
mesh_terms: D000818:Animals; D002417:Cattle; D003198:Computer Simulation; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005269:Femur / Q000473:pathology / Q000601:surgery*; D007101:Immersion; D066298:In Vitro Techniques; D053685:Laser Therapy / Q000295:instrumentation*; D007834:Lasers; D008954:Models, Biological; D010027:Osteotomy / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D025321:Surgery, Computer-Assisted / Q000295:instrumentation / Q000379:methods; D014867:Water
chemical_list: D014867:Water