Two-Wavelength Spectral Interferometry Implementation for Studying the Ultrashort Laser Pulse Heated Targets Expansion

The chirped pulse spectral interferometry method was used to measure the copper-target free surface motion velocity under the impact of an ultrashort laser pulse with an intensity of ~10¹⁸ W/cm². In order to obtain information on the motion of plasma layers with different electron densities, a two-channel interferometer was developed, which provides registration of hydrodynamic parameters of the target expansion process for the probe laser radiation at 1054 and 527-nm wavelengths. The spatial and temporal characteristics of the phase shift and the target reflectivity for the probe radiation were measured, and the two critical-density surfaces velocity evolution over time were reconstructed.