Holographic interferometry of shock waves initiated by a gigawatt CO2 laser pulse in a transparent target

The method of pulse double-exposure holographic interferometry was used to visualize and to study quantitatively a shock wave propagating in a transparent Plexiglas target and initiated by the radiation from a high-power CO₂ laser focused on the plane target-vacuum interface. The changes in the refractive index, density of the target material, and the pressure in this material behind the front of a spherical shock wave were determined. Estimates were obtained of the pressure in a plane shock wave and it was found that the efficiency of generation of shock waves by CO₂ laser radiation was low. Interference and cumulation of shock waves inside the transparent target, as well as cumulation of an ablation laser plasma near the target were observed. The method could also be used to determine the spatial characteristics of the parameters behind the front of a shock wave initiated by a laser radiation pulse in a transparent target.