High-refractive-index materials such as LaF3, NdF3 and GdF3 and low-refractive-index materials such as MgF2, AlF3 and Na3AlF6 single thin films are deposited by a resistive-heating boat at different deposited rates and specific substrate temperatures on single crystal MgF2 substrate. Transmittances of all fluoride thin films are measured through commercial spectrometer in the ambient atmosphere. Optical constants of these films are determined by the envelope method and the factors effecting optical constants are studied. Result of this work may play an important role in the design and manufacture of cost-effective, mechanically and optically stable optical coatings for the VUV region.