• Laser interaction with transparent materials and tissue
• high speed imaging
• Nonlinear microscopy and laser nanosurgery
• Refractive Laser Surgery

By focusing an ultrashort laser pulse into transparent materials, a short-lived cavitation bubble can be generated in an aqueous environment. In the threshold range, this bubble has a lifetime of only a few billionths of a second and its maximum size is sometimes only one thousandth of the hair diameter. The investigation of the cavitation bubble dynamics is therefore a high metrological challenge.

Within the scope of my research work, an interferometric detection technique has been developed which allows the investigation of the dynamics of laser-generated cavitation bubbles in water and tissue with a temporal and spatial resolution never achieved before. This novel single-shot technique uses the backscattering of a continuous wave laser at the two interfaces of the front and back of the bubble wall. The analysis of the interferometric signal allows a precise and fast determination of the bubble dynamics.

Additional information about the dynamics of the cavitation bubbles and their interaction with each other can be obtained from short-term photographic images (see figure). Using the latest high-speed techniques, which can record more than two million images per second, insights of great importance can be gained for laser material processing, laser-based surgery on the eye, and the optical manipulation of biological cells.