Enhancement of the contrast of laser plasma emission spectra accompanying two-pulse irradiation of a surface by neodymium laser radiation

An experimental investigation was made of the contribution of the second pulse, during two-pulse irradiation of a surface with a 25-μs interpulse interval, to the formation of the emission spectrum of a laser plasma. An enhancement of the spectral contrast was found to occur because the second radiation pulse interacted efficiently with the surface, due to the breakdown region being bleached by the first pulse, and not with the vapor created by the first pulse, as was previously assumed.