Complete characterization of multipass gas cell using a high sensitive optical frequency-domain reflectometry
This paper reports on the experimental characterization by means of optical frequency-domain reflectometry of a White-type multipass gas cell used for trace gas spectroscopy. The fractional Lambertian reflections inevitably arising from the three high reflectivity mirrors of this multipass cell is precisely detected due to the high sensitivity of the reflectometer. Each bounce of light on the mirror surface generates backscattered light, which returns to the sensing system. Then, using the measured distribution of multiple back-reflections as a function of distance the position of the 3mm-thick CaF2 entrance window is clearly identified, thanks to the spatial resolution of 731µm. In addition, the physical distance between mirrors at both sides of the cavity is accurately assessed to be 40.72cm, delivering the exact optical path length of light inside the multipass cell of 30.9853m, which is an important parameter for improving the accuracy of the computation to retrieve the gas concentration from the measured light absorption spectrum.
European Workshop on Optical Fibre Sensors (EWOFS 2023), M. Wuilpart, C. Caucheteur (Eds.), Mons (Belgium), pp. 21
This project has received funding from Horizon 2020, the European Union’s Framework Program for Research and Innovation, under grant agreement No.101015825 (TRIAGE).