Stray light testing of the PROBA V payload

The Centre Spatial de Liège in Belgium (CSL) has developed a stray light test facility for In Field and Out of Field of View stray light characterization of small Earth observation satellites. The first tested satellite is PROBA V, a small ESA satellite, developed by a Belgian consortium, dedicated to replace the SPOT VGT on SPOT missions. The test results demonstrate that the stray light performance of both PROBA V and the test facility are excellent and are in line with the model predictions. The new facility is designed for in-field and far field stray light characterization: intensities dynamic range up to 108:1 for in-field and up to 1010:1 for far field stray light in the visible to SWIR spectral ranges. Moreover, from previous stray light tests performed at CSL, vacuum conditions are needed for reaching the 10-10 rejection requirement mainly to avoid air/dust diffusion. To fulfill these requirements the stray light facility is built in one of CSL vacuum chamber located in a class 100. The large dynamic range required is achieved by using a high radiance point source allowing small diverging collimated beam. A lot of care is taken in the design of the collimator focal plane to provide a highly purely collimated luminance. Previous articles have presented the principle, the concept and a detailed analysis of the facility for stray light characterization of EO satellites. This paper goes a step forward with the presentation of actual test facility description and results obtained on PROBA V EO satellite. The achieved results are put in parallel to the modeled computed values.