University of Ljubljana, Faculty of Mechanical Engineering, Aškerčeva 6, SI-1000 Ljubljana, Slovenia.
J Biomed Opt. 2012 Jul;17(7):075006. doi: 10.1117/1.JBO.17.7.075006.
When an erbium-laser pulse is directed into water through a small-diameter fiber tip (FT), the absorption of the laser energy superheats the water and its boiling induces a vapor bubble. We present the influence of different FT geometries and pulse parameters on the vapor-bubble dynamics. In our investigation, we use a free-running erbium: yttrium aluminum garnet (Er:YAG) (λ=2.94 μm) laser that was designed for laser dentistry. Its pulse is directed into the water through FTs with a flat and conical geometry. Our results show that in the case of the conical FT, a spherical bubble is induced, while a channel-like bubble develops for the flat FT. The ratio between the mechanical energy of the liquid medium and the pulse energy, which we call the optodynamic energy-conversion efficiency, is examined using shadow photography. The results indicate that this efficiency is significantly larger when a conical FT is used and it increases with increasing pulse energy and decreasing pulse duration. The spherical bubbles are compared with the Rayleigh model in order to present the influence of the pulse duration on the dynamics of the bubble's expansion.
当铒激光脉冲通过小直径光纤尖端（FT）进入水中时，激光能量的吸收会使水过热，其沸腾会产生蒸汽泡。我们研究了不同 FT 几何形状和脉冲参数对蒸汽泡动力学的影响。在我们的研究中，我们使用了一种专为激光牙科设计的自由运行的掺铒钇铝石榴石（Er:YAG）（λ=2.94μm）激光。其脉冲通过具有平面和圆锥形几何形状的 FT 进入水中。我们的结果表明，在圆锥形 FT 的情况下，会产生一个球形气泡，而对于平面 FT，则会产生一个通道状气泡。使用阴影摄影检查了我们称之为光动力能量转换效率的液体介质的机械能与脉冲能量之间的比值。结果表明，当使用圆锥形 FT 时，该效率显著增大，并且随着脉冲能量的增加和脉冲持续时间的减小而增大。将球形气泡与瑞利模型进行了比较，以便呈现脉冲持续时间对气泡膨胀动力学的影响。
