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W Lauterborn

Publications and source records attributed to W Lauterborn.

24 records · Page 2Linked to original sources
PubMed1986

Cavitation bubble dynamics and acoustic transient generation in ocular surgery with pulsed neodymium: YAG lasers.

The authors have investigated the application of mode-locked and Q-switched Neodymium:YAG (Nd:YAG) lasers in ocular surgery by means of high-speed photography and hydrophone measurements. The incisive effect relies on the optical breakdown at the laser focus. Cavitation bubbles and acoustic transients are thereby generated. Their size and pressure amplitude have been measured at various laser-pulse energies. With a pulse energy of 5 mJ, the bubble is 1.5 to 2.3 mm in diameter and the pressure of the acoustic transient is 9 to 16 bar (130 to 230 psi) at a distance of 18 mm from the focal point. Bubble size and amplitude of the pressure pulse are always approximately 50% higher with a Q-switched laser than with a mode-locked laser. However, the size of the ruptures produced in a polyethylene membrane by the laser pulses is the same for both modes of operation. The energy balance shows that not only mechanical effects, but also thermal mechanisms are responsible for photodisruption.

Acoustics↗
PubMed1986

[Cavitation bubble dynamics and shock wave generation in eye surgery using the pulsed neodymium:YAG laser].

In a model experiment using polyethylene membrane in balanced salt solution the processes which take place during posterior capsulotomy with pulsed Nd:YAG lasers were investigated by means of high-speed photography and hydrophone measurements. It was found that cavitation bubbles with a maximum diameter of 1.5 to 2.3 mm develop at the focal point even with a pulse energy of 5 mJ; i.e., their spatial extent is much greater than that of the ruptures observed. Furthermore, during optical breakthrough and when the bubble collapses shock waves are generated with a pressure amplitude of 9 to 16 bat at a distance of 18 mm or 162 to 288 bar at 1 mm. Previous estimates ranged from more than 0.1 bat at 15 mm to several kilobar at 1 mm. Above a certain threshold value the energy of the cavitation bubble and of the shock waves is approximately proportional to the energy of the laser pulses with which they are generated. At the same time pulse energy the diameter of the bubbles generated by Q-switched lasers is around 1.5 times as large as those generated by model-locked lasers--the bubble energies are more than three times as great. The shock wave amplitudes after O-switched pulses are likewise 1.5 times as great as after mode-locked pulses and the energy of the shock waves is approximately double. Nevertheless, the size of the holes caused in a polyethylene membrane with a pulse energy of 2 mJ to 5 mJ does not depend on the laser operating mode. Thus, with the polyethylene membrane, no great correlation was found between the mechanical energy acting on it and the size of the holes thus created.(ABSTRACT TRUNCATED AT 250 WORDS)

Cataract Extraction↗