A newly designed high-spectral-resolution Rayleigh temperature lidar based on two-stage Fabry–Perot interferometer

Abstract

A two-stage Fabry–Perot interferometer (FPI)-based high-spectral-resolution (HSR) Rayleigh temperature lidar technology is proposed that is capable of simultaneously detecting tropospheric temperature and aerosol optical properties with high-precision. The system structure is designed and the measurement principle is analysed. A two-channel integrated FPI used forming a two-stage FPI ensures the relative stability of the two FPI spectrums. The first-stage FPI with high spectral resolution can effectively separate Mie and Rayleigh signals to derive the signal components. Two adjacent-order transmission spectrums of the second-stage FPI are just located in the two wings of Rayleigh–Brillouin (R–B) scattering spectrum to measure temperature. Two multimode polarization insensitive optical circulators used in receiver system can achieve high-efficiency utilization of signals. A narrow linewidth semiconductor laser at 852 nm is used as light source. Using the selected and optimized system parameters, the lidar performance simulation results show that in the sunny weather conditions for 0.15WSr–1 m–2 nm–1 sky brightness, with 0.3 W laser power, a 30 cm diameter telescope, 60 m range resolution and 30 min observation time, the temperature measurement errors are below 0.4 K in night-time and below 1.6 K in daytime; the relative measurement errors of backscatter ratio are below 0.04% in night-time and below 0.13% in daytime respectively up to 6 km height. Compared with the traditional FPI-based HSR technique, the technique we proposed can improve the detection accuracy of temperature by 2.5 times and can also significantly improve the detection accuracy of backscatter ratio.