New AOTF-based instrumental concepts for atmospheric science

Acousto-optical tunable filters (AOTFs) are still little known to the Earth atmosphere remote sensing community. The bulk of passive atmospheric remote sensing instruments remains divided into two families: those relying on interferometric techniques (mostly for the long-wave absorbing species), and those based on diffraction gratings (better suited for UV-VIS absorbing species). Still, AOTFs have some unique features which should deserve more attention, in particular their angular acceptance, and their polarization sensitivity. The first one because it allows to work in an imaging setup, the second because many atmospheric processes have a polarizing effect. In this paper, we will present different AOTF-based instrument concepts (or even prototypes) which take advantage of these features in order to improve the sate-of-the-art of measurement techniques in several fields of atmospheric science. We will first present the improved NO2 camera: its new capabilites, the subsystems which have been changed, and some preliminary results. Then, we will discuss two other potential applications: the study of the solar spectral irradiance variability in the UV, and the detection of auroral polarized emissions. For each concept, we will discuss the current challenges faced by the existing instruments, and analyze how the use of AOTFs could overcome them. A suggestion for the AOTF selection will be made, and the expected instrument performance will be estimated.