A ZBLAN (ZrF4-BaF2-LaF3-AlF3-NaF) glass film is synthesized for the fi
rst time on the inner surface of a ZBLYAN (ZrF4-BaF2-LaF3-YF3-AlF3-NaF
) support tube. The maximum deposition rate is about 60 mum/h. The com
position of the ZBLAN-glass film is controlled with the vaporizing tem
peratures of the starting materials, but compositional distribution is
observed along the preform axis. The thermal properties of the synthe
sized glass film are nearly the same as those of ZBLAN glass synthesiz
ed by the conventional melt-casting method.