OPTIMIZATION OF TETRAGONAL KTA1-XNBXO3-FE CRYSTALS AS STORAGE MATERIALS FOR DOUBLE-EXPOSURE HOLOGRAPHIC-INTERFEROMETRY

Double-exposure holographic interferometry with as-grown and oxidized iron-doped tetragonal potassium tantalate-niobate (KTN:Fe) crystals as a photorefractive storage material is presented. The influence of oxi dation treatments on the light-induced refractive index change and dec ay time constant is investigated for different external electric field s and spatial frequencies. The experimental findings can be explained in terms of a charge transport model which assumes one kind of photore fractive centres with hole conductivity only. The fringe contrast and exposure time of double-exposure holographic interferograms are determ ined. The displacement of a test target is evaluated from interferogra ms utilizing a quasi-heterodyne technique. For that purpose a fully au tomatically working computer program is developed.