Acoustic transient generation in pulsed holmium laser ablation under water
Acoustic transient generation in pulsed holmium laser ablation under water
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水下脉冲钬激光烧蚀中的声瞬态产生
DOI：
10.1117/12.182961
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
H. Weber
中科院分区：
文献类型：
--
作者：
T. Asshauer;K. Rink;G. Delacretaz;R. Salathé;B. Gerber;M. Frenz;H. Pratisto;M. Ith;V. Romano;H. Weber
在这项研究中，脉冲钬激光烧蚀过程中的声学瞬态的作用。为此，研究了通过光纤在水中传输的2.12微米Cr：Tm：Ho：YAG激光脉冲产生的空化气泡的破裂。记录了单个气泡产生声学瞬变的多次连续崩溃。脉冲持续时间从130 - 230微秒变化，脉冲能量从20 - 800 mJ变化。使用400和600微米的纤维直径。用1微秒频闪灯或5 ns 1064 nm Nd：YAG激光照射的时间分辨快速闪光照相法观察了气泡的溃灭行为。PVDF针探头换能器用于观察声瞬态并测量其压力幅值。在某些条件下，在崩溃阶段结束时，气泡发出高达几百巴振幅的球形声瞬变。在第一次塌陷后，观察到两次反弹，导致进一步的声学瞬态发射。在水下固体表面附近产生的气泡在其发展期间被吸引向表面。产生声学瞬变的塌陷的最后阶段直接发生在表面上，使其暴露于最大压力振幅。我们的研究结果表明，在关节镜检查或血管成形术中，钬激光在液体环境中应用时可能会造成不必要的组织损伤，这可能会限制激光脉冲持续时间和能量的选择。
In this study the role of acoustical transients during pulsed holmium laser ablation is addressed. For this the collapse of cavitation bubbles generated by 2.12 micrometers Cr:Tm:Ho:YAG laser pulses delivered via a fiber in water is investigated. Multiple consecutive collapses of a single bubble generating acoustic transients are documented. Pulse durations are varied from 130 - 230 microsecond(s) and pulse energies from 20 - 800 mJ. Fiber diameters of 400 and 600 micrometers are used. The bubble collapse behavior is observed by time resolved fast flash photography with 1 microsecond(s) strobe lamp or 5 ns 1064 nm Nd:YAG laser illumination. A PVDF needle probe transducer is used to observe acoustic transients and measure their pressure amplitudes. Under certain conditions, at the end of the collapse phase the bubbles emit spherical acoustic transients of up to several hundred bars amplitude. After the first collapse up to two rebounds leading to further acoustic transient emissions are observed. Bubbles generated near a solid surface under water are attracted towards the surface during their development. The final phase of the collapse generating the acoustic transients takes place directly on the surface, exposing it to maximum pressure amplitudes. Our results indicate a possible mechanism of unwanted tissue damage during holmium laser application in a liquid environment as in arthroscopy or angioplasty that may set limits to the choice of laser pulse duration and energies.