Pulsed-laser interaction with liquids

Abstract

Rapid vaporization of liquids on a pulsed-laser-heated surface Background The laser-beam interaction with materials in liquid environments exhibits unique characteristics in a variety of technical applications. The explosive vaporization of liquids induced by short-pulsed laser irradiation is utilized in laser cleaning to remove micro-contaminants (Park et al ., 1994) and in medical laser surgery. Physical understanding of superheated liquids and liquid-to-vapor phase transitions has been sought in order to achieve better control of such applications. The transient development of the bubble-nucleation process and the onset of phase change were monitored by simultaneous application of optical-reflectance and -scattering probes (Yavas et al ., 1993). The numerical heat-conduction calculation also shows that the solid surface achieves temperatures of tens of degrees of superheat (Yavas et al ., 1994). Real-time measurement of the surface temperature transient in the course of the laser-induced vaporization process is needed, since the surface temperature is an important parameter in heterogeneous nucleation. The kinetics of heterogeneous bubble nucleation and the growth dynamics have long been a subject of intense research interest (Skripov, 1974; Stralen and Cole, 1979; Carey, 1992). Enhanced pressure is produced in the interaction of short-pulsed laser light with liquids (Sigrist and Kneubuhl, 1978). The efficient coupling of laser light into pressure is of interest in many technical and medical areas, such as laser cleaning to remove surface contaminants, laser tissue ablation, corneal sculpturing (Vogel et al ., 1990), and gall-stone fragmentation (Teng et al ., 1987).