Hannover 2016 – scientific programme
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P: Fachverband Plasmaphysik
P 8: Laser Plasmas I
P 8.3: Talk
Tuesday, March 1, 2016, 15:15–15:30, b302
Analysis of Laser-Induced Plasma Dynamics by Coherent Diffractive Imaging — •Neeke Rothe1, Hannes Bassen1, Christoph Merschjann2, Thomas Fennel1, and Stefan Lochbrunner1 — 1Universität Rostock, D-18059 Rostock — 2Freie Universität Berlin, D-14195 Berlin
Studying the dynamics of laser-induced solid-density plasmas is of central interest for understanding the response of condensed matter targets to intense laser radiation, e.g. for optimizing laser machining. Furthermore, corresponding experiments open a route to investigate the properties of warm dense matter. Here we describe a technique to analyze the spatio-temporal evolution of laser plasmas in thin metallic foils with high resolution by combining ultrafast pump-probe techniques with two-dimensional diffractive imaging. From the recorded diffraction pattern a lateral 2D-map of the complex transmittance is obtained by inverting the holographic phase problem. From the temporal evolution of the resulting 2D-optical parameter maps details of the ionization, heating and ablation dynamics realized in the microplasma will be extracted. A dense laser plasma is generated by exciting a 30 nm thick gold foil with tightly focused pulses at 800 nm (τpump=50 fs). The plasma evolution is probed by delayed 400 nm pulses in transmission and the resulting diffraction pattern of the probe beam is recorded by a CMOS camera. By compressing the probe pulses, a time resolution of 50 fs is achieved. The experimentally observed diffraction patterns exhibit changes between 0 and 2000 ps, reflecting the temporal evolution of the plasma.