Remote sensing instrument for solid samples based on open-path atomic emission spectrometry

Design considerations and development steps towards the construction of an open-path laser-induced plasma spectrometer for remote elemental measurements are presented and the main variables influencing the analytical signal discussed. The instrument is based on a coaxial optical design where the interrogating laser beam and the returning plasma light share the same optical axis. This scheme allows both tight focusing of the infrared laser radiation to induce a plasma on a remote sample surface and collection of the ultraviolet-visible plasma emission through the same open air path. The selection of the optical scheme and the different components of the instrument are discussed on the basis of the measurement range, the light throughput and signal-to-noise ratio considerations. The results presented demonstrate the feasibility of the open-path laser-induced plasma spectrometry approach to remote atomic-emission spectrometry in the hundred meters range. Based on these results, additional estimations evidence the potential of the technique for measurements in the thousand meters range.