A demonstration of spatial heterodyne spectrometers for remote LIBS, Raman spectroscopy, and 1D imaging

• Published in: Spectrochimica acta. Part B: Atomic spectroscopy 2021-05, Vol.179, p.106108, Article 106108
• Main Authors: Fessler, K. Alicia Strange, Waldron, Abigail, Colón, Arelis, Carter, J. Chance, Angel, S. Michael
• Format: Article
• Language: English
• Subjects: Analytical methods; Field of view; Imaging; Imaging techniques; Lasers; LIBS; Monolithic Raman spectrometer; Photodegradation; Raman; Raman spectroscopy; Regions; Remote LIBS; Remote Raman; Resolution; Scattering; Shot noise; Signal to noise ratio; Spatial discrimination; Spatial heterodyne Raman spectrometer; Spatial heterodyne spectrometer; Spatial resolution; Spectra; Spectral resolution; Spectrometers; Spectrum analysis
• ISSN: 0584-8547; 1873-3565
• DOI: 10.1016/j.sab.2021.106108

Three spatial heterodyne Raman spectrometers, one free standing, the others monolithic, have been used for remote Raman and LIBS for samples at a distance of 4.5 m and 1D Raman imaging. The wide area measurement capability of the SHS was demonstrated and shown to reduce sample photodegradation in the case of Raman, using large laser spots on the sample, without loss of signal or decreased spectral resolution. 1D Raman imaging using a free standing SHRS and a monolithic SHRS was demonstrated and shown to provide better signal-to-noise ratio (SNR) spectra for heterogenous samples than spectra measured without imaging. Improved SNR using 1D imaging is the result of spatial separation of the signal from different areas of the sample, which reduces the contribution of shot noise from stronger scattering sample regions to more weakly scattering adjacent sample regions. For 1D imaging of adjacent samples, within the field-of-view (FOV) of the spectrometer, the SNR improved up to four times, with no loss of spectral resolution or spectral range, and a spatial resolution of 280 μm was demonstrated for samples located at 4.5 m from the spectrometer. •Benchtop and monolithic spatial heterodyne Raman spectrometers were used for remote Raman and LIBS at 4.5 m.•For Raman, a large field of view allowed reduced sample photodegradation with no loss of signal or spectral resolution.•1D SHRS Raman imaging provides higher signal-to-noise ratio for heterogenous samples than spectra measured without imaging.