Method and composition for creating gradient-index glass

Claim 1

An ion exchange method for producing a gradient-index profile in a glass body providing monovalent outdiffusing cations, which method comprises the steps of combining an amount of monovalent metal salt which provides silver monovalent cations other than the outdiffusing cations which are exchanged with the monovalent cations of the glass with an amount of metal salt containing non-monovalent cations which do not exchange with the outdiffusing cations and which will complex therewith in a container to form a mixture, said amounts of salt in said mixture being sufficient to yield a delta-n substantially equal to a delta-n obtained when an amount of pure salt containing monovalent cations is used alone and/or being sufficient to yield a substantial depth of diffusion while counteracting poisoning of the mixture by the outdiffusing cations, thereby enabling a large reduction in the amount of the monovalent metal salt employed for obtaining an equivalent delta-n, heating said mixture until said mixture is molten to provide a salt bath of said mixture, and contacting said glass with said salt bath for a time sufficient to obtain ion exchange between said monovalent cations of said glass and of said metal salt containing monovalent outdiffusing cations and yield said gradient-index profile and/or depth of diffusion.