| 摘要 |
1527436 Doped glass articles P M B DE MACEDO and T A LITOVITZ 18 March 1976 [18 March 1975 26 Nov 1975] 10935/76 Heading C1M A glass article, such as a waveguide or preform therefor, having a desired refractive index distribution is made by precipitating a dopant in the interconnected pores of a matrix (e.g. acid leached borosilicate glass) without substantial evaporation of the dopant solvent, drying after initiation of the precipitation, regulating the rate of heating to remove solvent and, where necessary decomposition products, from the pores to give the desired dopant distribution, and collapsing the porous matrix to solid form. During the leaching of the initial glass the leach acid may be cooled to precipitate boric acid. The dopant may be precipitated by thermal and/or chemical treatment, by solvent exchange or by common ion effect. The doped matrix may be treated with solvent to provide an undoped surface layer and the removal of solvent may be at least initially under vacuum. |
