Imaging of the spatial distribution of atoms in an optical-breakdown plasma, with one-dimensional coherent hyper-Raman scattering

A technique based on coherent four-wave mixing with a hyper-Raman resonance in wide beams was developed for line-by-line reconstruction of the spatial distribution of excited atoms in a laser-produced plasma. This method was used to study the spatial distribution of excited lead atoms in an optical- breakdown plasma formed on a metal target. A comparison was made of the tec hnique of constructing plasma images line-by-line with a four-photon techni que of point-by-point measurements. Estimates were obtained of the spatial resolution of the proposed technique. Potential applications of this approa ch in plasma diagnostics were analysed.