On-axis time-resolved spatial characterization of shock-induced refractive fringes in liquid water

Abstract

We report here the on-axis measurement of time-resolved spatial characterization of refractive fringes due to nanosecond-laser-induced shock waves in liquid water. The complex shadowgraphic fringes due to interference of multiple shock waves observed in the transverse measurements are completely avoided in the on-axis mea- surements due to the fact that the outermost region of the shock front acts as a radially symmetric phase object to theprobebeam,refractionfrom whichresultsin cleanandcontinuousfringesobservedby theintensifiedcharge coupled detector (ICCD) detector. A detailed analysis of different types of time-resolved fringes obtained in the on-axis measurement for fixed laser pulse energy leads us to an alternate and better way to analyze the fringes to obtain the shock wave velocity and the density profile in the entire region surrounding the shock origin, which will enable 3D imaging of shock wave dynamics. © 2013 Optical Society of America.