3D imaging of water ice under high-pressure non-hydrostatic load by time-domain Brillouin scattering
Résumé
Time-domain Brillouin scattering (TDBS) technique is an opto-acousto-optic pumpprobe technique [1] that uses ultrashort laser pulses to generate coherent acoustic pulses (CAPs) of picoseconds duration in a solid sample and follow their propagation in order to image inhomogeneities of acoustic, optical and/or photo-elastic parameters of materials transparent to the probe light wavelength [2]. This technique presents an axial resolution deeply sub-optical (to nm-scale), controlled by the CAPs width, and a lateral one down to the optical diffraction limit, controlled by lateral focusing of used laser beams. Detection of propagating CAPs is possible because they scatter time-delayed probe laser pulses heterodyned by the probe-pulse reflections from stationary sample surfaces, giving rise to an oscillating component in a transient reflectivity signal: the so-called Brillouin oscillation (BO).
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