Line-by-line imaging of laser-produced plasmas using one-dimensional coherent four-wave mixing

An experimental technique based on coherent one-dimensional four-wave mixin g (FWM) with hyper-Raman resonances was developed for fine-by-line imaging of the atomic distribution of excited atoms in a low-temperature plasma of optical breakdown, Comparison of the measured time dependences of FWM inten sity and plasma transmission with the results of numerical simulations of p lasma expansion allows the assessment of the influence of phase mismatch an d one-photon absorption on FWM in a laser-produced plasma and demonstrates that FWM images of atomic spatial distributions free of distortions due to phase mismatch and absorption can be obtained for certain stages of plasma expansion. Copyright (C) 2000 John Wiley & Sons, Ltd.