PROBE — Profile Resolution Obtained by Excitation

Abstract

A new approach for evaluating, with spatial resolution, the line of sight properties of a specific constituent is proposed. This PROBE (profile resolution obtained by excitation) concept involves the use of two counter-propagating laser pulses; a pump pulse to condition the medium and a probe pulse to interrogate the medium where the pulses overlap. In this way, information regarding the spatial distribution of a species is transformed into temporal information in the form of a change in the amplitude of a returned probe pulse. For certain situations the PROBE technique offers several advantages over scattering or laser induced fluorescence methods. A theoretical formulation of the concept clearly indicates the importance of the lifetime of the pumped state.