Modeling the JANUS stray-light behavior

Abstract

JANUS is the camera of the ESA mission JUICE, dedicated to high-resolution imaging in the extended-visible wavelength region (340 - 1080nm). The camera will observe Jupiter and its satellites providing detailed maps of their surfaces and atmospheres. During the mission, the camera will face a huge variety of observing scenarios ranging from the imaging of the surfaces of the satellites under varying illumination conditions to limb observation of the atmospheres. The stray-light performance of JANUS has been studied through non-sequential ray-tracing simulations with the aim to characterize and optimize the design. The simulations include scattering effects produced by micro-roughness and particulate contamination of the optical surfaces, the diffusion from mechanical surfaces and ghost reflections from refractive elements. The results have been used to derive the expected stray-light performance of the instrument and to validate the instrument design.