Fourier Transform Spectrometry with a Near Infrared Supercontinuum Source
Chris A. Michaels, Tony Masiello, Pamela M. Chu
Optical fiber based supercontinuum light sources combine the brightness of lasers with the broad bandwidth of incandescent lamps and thus are promising candidates for sources in spectroscopic applications requiring high brightness and broad bandwidth. Near-infrared (IR) Fourier transform (FT) spectrometry with a supercontinuum (SC) light source is investigated. The efficient, collimated propagation of broad bandwidth SC light through a 18 m pathlength multipass cell is demonstrated. A normalized spectral difference is calculated for the SC spectrum on consecutive FT mirror scans and is found to vary by less than 0.5% indicating excellent spectral stability. The RMS noise on 100% lines is obtained as a function of the number of mirror scans at 0.125, 2 and 16 cm-1 resolution for both the SC and conventional tungsten lamp source. The SC source has approximately a factor of ten times more noise than the lamp under comparable conditions for each resolution and data acquisition time. Near-IR FT spectra of methane and methyl salicylate, acquired with both the SC and lamp source are reported. These spectra illustrate the advantage the SC source has over the incandescent source in that it can efficiently traverse long pathlengths, thus providing a sensitivity advantage. The spectra also demonstrate the disadvantage of the SC source with respect to the lamp in the increased level of amplitude noise. Prospects for the future use of SC sources in absorbance spectroscopy, including possible noise mitigation strategies, are briefly discussed.
, Masiello, T.
and Chu, P.
Fourier Transform Spectrometry with a Near Infrared Supercontinuum Source, Applied Spectroscopy, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=832380
(Accessed September 21, 2023)