Space-resolved measurement and 2D-mapping of material parameters using multi-angle reflection ellipsometry in W-band

In this paper a free-space method is presented for space-resolved measurement of the relative permittivity and thickness of a single layer dielectric material in the W-band. The reflection of parallel and perpendicularly polarized waves from the material under test is measured with a polarimetric linear array. Synthetic aperture focusing of the raw data is performed, in order to obtain space-resolved reflection coefficients, from which the material parameters are determined using the spec-troscopic multi-angle reflection ellipsometry technique. Results of the proposed method are presented in the frequency range of 75-95 GHz for low loss materials with a few millimeters of thickness. The relative uncertainty in determining the thickness and ε´ of Teflon is 2% and 3% respectively. The capability of the method to accomplish space resolved material characterization is demonstrated by two dimensional mapping of the relative permittivity of Teflon with a high accuracy.