Optical properties of new borolanthanum oxide-fluoride glasses

Optical properties and crystallizability of glasses of boron oxide - lanthanum oxide - yttrium fluoride system were studied with the aim of search of optimum contents for glasses which could be used in mass filmphotooptics. Oxides and fluorides of barium, calcium, strontium, zirconium, zinc, aluminium were introduced into initial glass. Addition of 2 mol.% of BaO, BaF2, CaO, CaF2, SrF2 leads to formation of crystal skin on the surface of casting and to crystal inclusions in volume of glass. Glass with 7 mol.% of Al2O3 in its content has the following optical constants: ne=1.73553, Ve=54.8. This content was taken as the base for the further development of practical glasses.