Analysis of Misalignment Sensitivity of Generalized Ring Resonator for the Trace Gas Concentration Detection Instrument Based on CRDS

Abstract

Cavity Ring-Down Spectrometer (CRDS) (Romanini et al., 1997) has been widely used in the fields of atmospheric chemistry, meteorology, air pollution and greenhouse gas emission, ecological environment and ecological hydrology research and public safety assurance. However, in order to maximize the measurement sensitivity of the target analyte of the cavity ring down spectrometer, the absorption measurement should be selected at the target line absorption peak (Kevin K. Lehmann et al., 1996). In addition, it should be noted that the interference of absorption lines of the same or other species should be reduced, in order to achieve a higher accuracy detection of the instrument that improving the spectral accuracy become more critical (Altshuler et al., 1977). In the paper, we have considered the existence of the self-conjugate rays in the resonator which is consisted of a number of mirrors and including spherical mirrors, the effect of spherical mirror misalignment in ring resonators was investigated. Then by utilizing the optical path turning reflection matrix, and the influence that caused by both the displacements of a spherical mirror and plane mirror in a nonplanar ring resonator have been obtained, and given the relation of the error transmission in both azimuth and pitch direction.