The VEM (Venus Emissivity Mapper) instrument is a DLR contribution to the EnVision (ESA – Cosmic Vision M5) and VERITAS (NASA-JPL – Discovery 15) missions. The role of this instrument will be to determine the composition of the surface by studying thermal emissions with observation in narrow spectral bands in the near-infrared.
To map the surface of Venus, the VEM instrument uses an infrared detector on which the selection of 14 narrow spectral bands is projected along a track on the ground. The multispectral filter, which contains these 14 bands, is integrated into an optical telescope called VEM-O. LESIA is responsible for supplying VEM-O to DLR. CNES assists LESIA in supplying the filter for VEM-O and entrusts BERTIN WINLIGHT and CILAS to design, develop, qualify and finally assemble the multispectral filters flight models.
In this paper, we will focus on the design of the 14 narrow bandpass filters constituting the multispectral assembly. For each filter, a specific design as been done involving Fabry-Perot and blocking functions, taking into account central wavelengths, spectral bandwidth, rejection spectral range and flatness requirements.
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