LOW-TEMPERATURE FAR-INFRARED ELLIPSOMETRY OF CONVERGENT-BEAM

Development of an ellipsometry to the case of a coherent far infrared irradiation, low temperatures and small samples is described, including a decision of the direct and inverse problems of the convergent beam ellipsometry for an arbitrary wavelength, measurement technique and a compensating orientation of cryostat windows. Experimental results are presented: for a gold film and UBe13 Single crystal at room temperature (lambda = 119 mum), temperature dependencies of the complex dielectric function of SrTiO3 (lambda = 119, 84 and 28 mum) and of YBa2Cu3O7-delta Ceramic (lambda = 119 mum).