Investigation of Atmospheric O2X3Σ-g to b1Σ+g using Open-path Tunable Diode Laser Absorption Spectroscopy
A tunable diode laser absorption spectroscopy (TDLAS) device fiber coupled to a pair of 12.5 in. telescopes was used to study atmospheric propagation for open path lengths of 100–1,000 meters. More than 50 rotational lines in the molecular oxygen A-band O2X3Σ-g to b1Σ+g transition near 760 nm were observed. Temperatures were determined from the Boltzmann rotational distribution to within 1.3 % (less than ±2 K). Oxygen concentration was obtained from the integrated spectral area of the absorption features to within 1.6 % (less than ±0.04 × 1018 molecules/cm3). Pressure was determined independently from the pressure-broadened Voigt lineshapes to within 10 %. A fourier transform interferometer (FTIR) was also used to observe the absorption spectra at 1 cm−1 resolution. The TDLAS approach achieves a minimum observable absorbance of 0.2 %, whereas the FTIR instrument is almost 20 times less sensitive. Applications include atmospheric characterization for high energy laser propagation and validation of monocular passive raging.
Applied Physics B: Lasers and Optics
Rice, C.A., Gross, K.C. & Perram, G.P. Investigation of atmospheric O2X3Σ g- to b1Σg+ using open-path tunable diode laser absorption spectroscopy. Appl. Phys. B 111, 173–182 (2013). https://doi.org/10.1007/s00340-012-5243-y