Gas measurement method based on Angle dependence of F-P cavity transmittance

Correspondence: Pinhua Xie(phxie@aiofm.ac.cn)

This study introduces a gas measurement method employing Fabry–Pérot (F-P) interferometer correlation spectroscopy. The methodology capitalizes on the angle-dependent characteristics of the F-P interferometer transmission spectrum, aligning interference peaks with gas absorption cross-section features. The experimental setup features a dual-beam synchronous incidence F-P cavity, and a forward model is developed to scrutinize the impact of system parameters on measurement outcomes. A comprehensive investigation into factors affecting the effective transmittance of the F-P cavity is conducted. The analysis reveals that controlling the beam divergence angle significantly influences the spectral resolution of gas measurements, particularly when utilizing the angle-dependent nature of the F-P cavity with oblique beam incidence. Ultimately, this study conducts concentration measurement experiments for gases such as SO2 and CH4, demonstrating the method's efficacy in quantitatively assessing gas concentrations. Given that this approach relies on hardware-based spectral selection to achieve differential measurements, it emerges as a highly selective method for gas measurement. It exhibits robust resistance to cross-interference, holding promise for applications in imaging and facilitating rapid measurements.

Funding. Project supported by the National Natural Science Foundation of China (Grant No. U19A2044), the National Natural Science Foundation of China (Grant No. 41975037), and the Key Technologies Research and Development Program of Anhui Province (Grant No. 202004i07020013).

Acknowledgment. My sincere gratitude goes to Mr. Yingjie Ye for his invaluable assistance in conducting the experiments.