Assessing the feasibility of a low-throughput gated echelle spectrograph for Laser-induced Breakdown spectroscopy (LIBS)-Raman measurements at standoff distances. (September 2022)

• Record Type: Journal Article
• Authors: Muhammed Shameem, K.M.; Dhanada, V.S.; George, Sajan D.; Kartha, V.B.; Santhosh, C.; Unnikrishnan, V.K.
• Is Part Of: Optics & laser technology. Volume 153(2022)
• Publication Date: 2022-09
• Subjects: Remote analysis -- Laser-induced Breakdown Spectroscopy -- Raman Spectroscopy -- Echelle-gated detection; Optics -- Periodicals; Lasers -- Periodicals; Electronic journals; 621.366
• DOI: 10.1016/j.optlastec.2022.108264
• Languages: English
• ISSNs: 0030-3992

Abstract

Highlights: A single gated echelle spectrograph having simultaneous broadband and high resolution has been used here for the first time to measure the non-identical spectral emission lines (LIBS and Raman) at standoff distances, which eventually reduce the overall dimension and cost of the combined portable system. The high resolution of the echelle spectrograph in the combined system provides well-resolved Raman bands (as evident by the splitting of many fundamental bands in the Raman spectrum) along with the discrimination of thousands of closely lying atomic emission lines. The possibility of measuring Raman signals using a low-throughput echelle spectrograph through different colored glass bottles has also been demonstrated here. The practicability of measuring broadband emissions (e.g., LIF) using the combined echelle system has been investigated, and the results are presented here. Abstract: We have developed a potentially portable tabletop combined remote LIBS-Raman spectroscopy system using a high-resolution gated echelle spectrograph for measuring both atomic and molecular emission spectra at a standoff distance of 6.5 m. The system consists of a frequency-doubled Nd: YAG laser, a 4X beam expander, a Cassegrain telescope, and a gated echelle spectrograph. The unique advantages of simultaneous broadband coverage (250–850 nm) and high resolution of the echelle system have been employed for measuring the non-identical emission spectrums (LIBS and Raman) at remote distances. The viability and practicability of the low throughput gated echelle spectrograph for detecting the remote Raman signals were evaluated critically by recoding a series of organic chemicals and solid samples. Further, the feasibility of measuring Raman signals of organic chemicals through different colored bottles was also demonstrated. Additionally, the combined LIBS-Raman spectra of several medium Raman cross-section solids samples were recorded from a standoff distance of 6.5 m, and the results are presented here. The benefits of merging the LIBS and Raman spectroscopy system and the bidirectional use of these techniques for remote measurements have also been highlighted.