Multi-points scanning method for wavelength locking in CO2 differential absorption lidar

Differential absorption lidar (DIAL) is a promising technique for retrieving atmospheric CO2 concentration profiles, which help researchers gain an insight into the carbon cycle. The slight CO2 absorption line center frequency shift caused by pressure and temperature change causes reduced accuracy when using the DIAL technique. The ground-based DIAL performances, aimed at retrieving the vertical atmospheric CO2 concentration distributions, are markedly deteriorated by such interferences. The multi-points scanning method is presented and investigated to handle this problem. Experiments show that a transmitted laser can be locked at the desired ON wavelength with an average accuracy of 0.0956 pm and variance of 4.13E-8 pm at various altitudes ranging from 1000 to 9000 m using this proposed method.