@inproceedings{godwin98, author = {R. P. Godwin and E. J. Chapyak and S. A. Prahl and H. Shangguan}, title = {Laser Mass-Ablation Efficiency Measurements Indicate Bubble-Driven Dynamics Dominate Laser Thrombolysis}, booktitle = {SPIE Proceedings of Lasers in Surgery: Advanced Characterization, Therapeutics, and Systems VIII}, editor = {R. R. Anderson and K. E. Bartels and L. S. Bass and C. G. Garrett and K. W. Gregory and H. Lui and R. S. Malek and A. P. Perlmutter and L. Reinisch and P. J. Smalley and L. P. Tate and S. L. Thomsen and G. M. Watson}, year = {1998}, volume = {3245}, pages = {4--11}, abstract = {Mass removal experiments have been performed at the Oregon Medical Laser Center with 10 to 100\,mJ one microsecond laser pulses at optical wavelengths. Above the energy threshold for bubble formation, the laser mass ablation efficiency ($\mu$g/mJ) for removal of gel surrogate thrombus is nearly constant for a given experimental geometry and gel absorption coefficient. The efficiency in 'contact' experiments, in which the optical fiber delivering the energy is in close proximity to the absorbing gel, is approximately three times that of 'non-contact' experiments, in which the optical fiber is approximately 1\,mm from the gel. Mass removal occurs hundreds of microseconds after the laser deposition. Experimental data and numerical simulations are consistent with the hypothesis that jet formation during bubble collapse plays a dominant role in mass removal. This hypothesis suggests a model in which the mass removed scales linearly with the maximum bubble volume and explains the distinctive features, including the magnitude, of the mass removal.}, }