We investigate a measurement technique based on High Resolution Interference Microscopy (HRIM). HRIM allows the characterization of amplitude and phase of electromagnetic wave-fields in the far-field with a spatial accuracy that corresponds to a few nanometers in the object plane. The experimental tool working in transmission with a resolution of 20 nm in the object plane was presented in our previous work [1]. The accurate measurement of the optical characteristics below the classical resolution limit will be discussed.