| 摘要 |
PURPOSE:To reduce the dispersion of a compsn. and improve the stability thereof to devitrification by determining the optimum content of LiF in the compsn.; reducing the P and O contents; introducing much CaF2; and specifying the ratio of F<->/O<2->. CONSTITUTION:Cations in glass are represented by fluorides as follows: by mol, PF5 5-20%, AlF3 18-42%, CaF2 17-35%, SrF2 0-25%, SrF2+BaF2 8-33%, LiF 0.8-7%, MgF2 0-22%, ZnF2 0-5%, PbF2 0-2%, YF3 0-7%, LaF3 0- 7% and ZrF4 0-3%. Oxygen ions are substd. for part of the fluorine ions to regulate the ratio of F<->/O<2-> to 2.5-15. By this compsn. low dispersion, Be-free fluorophosphate optical glass excellent in charcteristics such as refractive index and Abbe's no. is obtd. without lowering the softening point. |
