2-micron high-repetition rate laser transmitter for biosphere-atmosphere flux measurements
Résumé
We describe the laser transmitter development of a new Heterodyne Differential Absorption Lidar (HDiAL). This new system is called COWI and is designed to make simultaneously atmospheric CO2 concentration and wind velocity measurements. The goal is to reach 10 ppm accuracy with 150 m - 10 s time and space resolutions and to be able to make CO2 fluxes measurement thanks to the wind velocity measurement capability. The 2 μm Ho:YLF ring laser is pumped by a Tm:fiber laser at 1940 nm. We describe our experimental set-up and the performances in the CW and pulsed regime. The injection seeded operation is currently under development and the first results will be presented. Instrumental simulations and experimental results show that a trade-off has to be found between the pulse lengths, the pulse energies and the pulse repetition rate to optimize CO2 fluxes measurements accuracy.