Optimization of a compact static interferometer based on ImSPOC technology for a wide field polar lights monitoring

Abstract

In the context of the creation of a Distributed Space Weather Sensor System (D3S), the European Space Agency (ESA) is planning to fly a miniaturized payload for the monitoring of the auroral emissions with the project Wide Field Auroral Imager (WFAI). In order to meet ESA's requirements for an Auroral Optical Spectral Imager (AOSI), CSUG will build a breadboard as a proof of concept based on Imager Spectrometer on Chip (ImSPOC) technology.Imaging Spectrometer on Chip (ImSPOC) technology consists of a matrix composed by multiple, low finesse, Fabry-Perot modules mounted in one unique structure. Each Fabry-Perot cavity has a fixed optical path difference distributed from optical contact up to maximum elevation in order to have the desired spectral resolution and the spectral coverage. So, in one snapshot it is possible to "scan" several optical path differences and reconstruct the spectrum for each point of the field of view. The advantage of this technology is to reduce the mass and dimensions but also that it collects sufficient number of photons allowing the observation of the faintest aurora (Not visible with naked eye) with short integration time. This makes it a particularly well-suited technology for small satellite payload design in the framework of polar lights monitoring.We present here the optimization of the ImSPOC technology in the context of WFAI mission. This optimization allows us to recorded polar lights spectra in the wavelength range of 350 to 950 nm within an exposure between 10 and 60 s. The field of view of the instruments is 57° × 57°, obtained by combination of 9 individual modules with small dimension (one module fits in a 60 × 45 × 55 mm 3 box). The simulated performances of the instrument are really encouraging. The spectrometer must have a spectral resolution of 1 nm at 350 nm.