Graphene Based THz Electromagnetic Imaging System for the Analysis of Artworks

In this paper, a graphene-based electromagnetic imaging system working in 140–220 GHz frequency band for nonintrusive analysis of 3D artwork is presented. A single-stage high-order frequency multiplier is used to generate the signal at the transmitter module, whereas the single-stage high-order subharmonic mixer acts as a signal detector at the receiver. Both modules exploit the nonlinear response of graphene sheets excited by an incident electromagnetic wave, to generate harmonic components and mixing products of the input signals, respectively. The transmitter and the receiver modules were implemented through an additive manufacturing process. The resulting electromagnetic imaging system prototype was applied to the analysis of ceramic vessels, showing its ability to detect enclosed objects and to obtain information in cross-sectional planes. Furthermore, the geometrical parameters and filling material characterization can be obtained by processing the frequency response of the scattered field.