Laser-induced cavitation phenomenon studied using three different optically-based approaches – An initial overview of results

Abstract

This report presents a study of shock wave and cavitation bubble dynamics induced by nanosecond laser pulses in pressurized water. Three methods were used to obtain data from the irradiated sample: (1) pump-probe laser flash shadowgraphy, (2) pressure wave sensing by means of a fiber optic interferometer hydrophone, and (3) a novel technique based on the modulation of spatial transmittance by the cavitation bubble. The medium used in these experiments was distilled water in a chamber under different pressure conditions which included values found in human intraocular liquid. It could be shown that while external pressure does not affect either the shock wave propagation or the initial bubble growth rate, it does affect the first collapse time of the bubble and its maximum diameter.Keywords: bubble; shock wave; microsurgery; pressure; intraocular.Zusammenfassung : Die vorliegende Arbeit untersucht die Dynamik von Schockwellen und Kavitationsblasen, die mittels Nanosekunden-Laserpulsen in unter Druck gesetztem Wasser erzeugt wurden. Dabei wurden drei unterschiedliche Methoden verwendet: (1) Laserflash-Verfahren, (2) Druckwellenmessung mittels faseroptischem Interferometer und (3) eine neuartige Technik basierend auf der Modulation der r ä umlichen Transmission durch die Kavitationsblase. Die Untersuchungen wurden an destilliertem Wasser unter unterschiedlichen Dr ü cken -u.a. auch physiologische Werte, wie sie intraokular vorkommen -vorgenommen, die mittels einer speziellen Druckkammer erzeugt wurden. Es konnte gezeigt werden, dass weder die Ausbreitung der Schockwelle noch das anf ä ngliche Blasenwachstum durch den ä u ß eren Druck beeinflusst wird, die Kollapszeit der Blase und ihr maximaler Durchmesser jedoch sehr wohl.Schl ü sselw ö rter: Blase; Schockwelle; Mikrochirurgie; Druck; intraokular.

Highly extended high density filaments in tight focusing geometry in water: from femtoseconds to microseconds

“…For incident laser energy of 130 μJ, shock wave speed is 2300 ± 200 m s −1 . The shock wave pressure can be estimated as 1.0 ± 0.1 GPa, which is similar to the results in [8,33,34].…”

Reconstruction of laser-induced cavitation bubble dynamics based on a Fresnel propagation approach

“…normally incident, which allows the light to pass through the bubble without being refracted; therefore, for any bubble size there is always a light spot right at the bubble center; this feature is reproduced in the theoretical shadowgraphs just as it appears also in our experimental laser pump-probe shadowgraphs [20,23] [ Fig. 5(d)].…”

“…Experimental Setup Figure 1 shows the experimental setup used to monitor plasma mediated cavitation bubble dynamics. It combines the STM technique and a high-speed video system [18,20]. Bubbles were produced by the pump laser, a Q-switched, 532 nm (frequency doubled), Nd:YAG, running at 10 Hz repetition rate with energy per pulse up to 820 μJ 57 μJ.…”

Laser Control of the Shock Wave Shape by Tightly Focused Femtosecond Laser Radiation

“…For example, in crystals focused femtosecond laser radiation generates phonons and shock waves and create microvoids, in liquids it generates cavitation bubble and shock waves. Shock waves define impact of laser irradiation in a far-field, because plasma is localized in a few microns [3][4][5][6][7][8]. These post effects have important practical usage.…”

“…So the dynamics of laser-matter interaction and exact pressure and energy distribution generated by shock wave should be known in such areas like nanosurgery and ophthalmology. Most of papers in this field describe temporal dynamics of shock wave propagation [1][2][3][4][5][6][7][8][9]. Observing shock wave propagation give an opportunity to estimate shock wave pressure, energy and as a result, its dynamics and to calculate amount of energy delivered to every point.…”