Optical Methods in Characterization of HTSC Thin Film Substrates

Short overview of optical methods which proved to be useful in the characterization of HTSC thin film substrates is presented. Preliminary tests in polariscopic arrangements, interferometric measurements, optical absorption and emission spectroscopy reveal macroscopic deficiencies of the crystal. Intentionally introduced impurity ions serve as probes of a local strength and symmetry of the crystal field. Results of optical study of SrLaGaO$\text{}_{4}$ and SrLaAlO$\text{}_{4}$ crystals are presented and discussed.