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The interior structures of the comets and asteroids, still poorly known, might hold a unique key to understand the early Solar System. Considering the interaction of an illuminated electromagnetic wave with this kind of targets, these ”objects” are very large compared to the applicable wavelength. Consequently, tomographic imaging of such targets, i.e., reconstructing their interior structure via multiple measurements, constitutes a challenging inverse problem. To reach this objective and to develop and test inverse algorithms, we need to investigate electromagnetic fields that have interacted with structures analogous to real asteroids and comets. In this study, we focus on the acquisition of these fields considering three methods: calculated fields obtained with (1) time and (2) frequency domain methods and (3) microwave measurements performed for an analogue model, i.e., a small-scale asteroid model.

Semiconductors like Si, Ge (and other compounds like GaAs, GaP, etc) show high values of their refractive index and low absorption in the visible (VIS) and near-infrared (NIR) ranges. Nanoparticles made of these high refractive index (HRI) materials have been recently proposed as an alternative to metallic ones to overcome their inherent ohmic losses. In addition, the excitation of coherent electric and magnetic resonances makes these HRI nanoparticles to become basic to build multifunctional elements in optical devices for controlling the directionality of the scattered radiation. Here, we present unambiguous experimental evidence in the microwave range that a dimer of spherical High Refractive Index dielectric particles behaves as an elementary block for building switching devices whose binary state only depends on the polarization of the incident radiation. The corresponding analysis has been carried out by means of the linear polarization degree of the scattered radiation at the right angle scattering configuration.

Thanks to the success of the 2D scattering fields databases that we have measured in the anechoic chamber of the Institut Fresnel and proposed to the inverse problem community, we are now extending these studies to 3D configurations. This introduces new challenges due to the low level of signal as well as its sensitiveness to small disturbances. A careful characterization of the experimental errors is therefore necessary and we focus therein on drift errors, as they are mainly responsible for the scattered field variations. The objective is double: improve scattered field measurement accuracy and reduce acquisition time as it can take several hours for one incident illumination for 3D inverse scattering applications. To compensate for this drift error, we propose a fast correction based on a limited spectral bandwidth criteria, with the benefit of no loss of information and no need of a priori knowledge on the scatterer. After introducing the measurement setup and describing this correction protocol, we highlight its influence on the acquisition process