Duration: 18 months
Measuring high altitude wind with a direct detection molecular Doppler UV lidar has many applications at ESA: Aeolus family missions, Aeolus Cal/Val, HAPS and meteorological studies. In particular, ADM-Aeolus observations have improved weather forecasts and climate models. For Aeolus, the spectral analyzer in ALADIN is a combination of double-edged Fabry-Pérot and Fizeau interferometers. However, this analyzer has limitations, including: 1-biases induced by atmospheric temperature, pressure and the presence of particles (requiring the Fizeau interferometer for corrections) 2-it is sensitive to laser drift (requires laser frequency lock) and 3-it has low angular acceptance 4-the signal is separated between the two interferometers leading to signal reduction. This leads to numerous calibration campaigns and reduced data quality. Until now, other spectral analyzer concepts have been explored without allowing a significant simultaneous improvement in robustness and precision.
We propose to explore an innovative solution for the spectral analyzer: the monolithic Quadri Mach-Zehnder (QMZ) interferometer. It is for us the best precision/robustness compromise among existing spectral analyzers. It is not sensitive to laser drift, atmospheric conditions and has a wide field of view. Additionally, a single analyzer could be 1-used for molecular and particle signal, 2-used to determine particle backscatter coefficients, extinction coefficient, and 3-extended with a dedicated channel for aerosol and cloud polarization analysis.
A critical point for this instrument is to develop robust solutions to aircraft and space conditions. We designed and manufactured the first monolithic molecular optimized QMZ interferometer. In this early technical development, we propose to mount the interferometer to obtain a complete spectral analyzer, test its performance and its compatibility of the instrument with airborne and space use. This would result in new capabilities for ESA missions.
