Single shot measurements of laser driven shock waves using ultrafast dynamic ellipsometry

Ultrafast dynamic ellipsometry, a diagnostic that measures both the shock-induced optical effects and the motion of shocked materials, has been implemented in a single shot form. This is accomplished using chirped pulse interferometry and probing the sample at two angles with both sand p-polarized light. The application of single shot ultrafast dynamic ellipsometry should prove important in future studies of shocked transparent materials and metals because it allows concurrent determination of the initial and shocked optical constants, shock and particle velocities, and the picosecond time dependence of these properties with a higher signal-to-noise ratio and less stringent sample requirements than multishot methods. The ability to infer both the initial and shocked refractive indices of the material eliminates the need for performing extra experiments to calibrate the window, greatly simplifying the analysis and making each shot a self-contained experiment. The implementation of this diagnostic is described, and its utility is demonstrated on a shocked thin film of polycarbonate. Analysis of the data employs a multilayer thin film model to calculate the reflectance as a function of the time-dependent layer thicknesses and optical properties. Hugoniot data for the thin film polycarbonate is presented along with the effect of shock compression on the refractive index, which is consistent with the Gladstone-Dale relation. (c) 2007 American Institute of Physics.