Radial gradient index (GRIN) lenses have a refractive index profile which varies radially outward from the optical axis. High numerical aperture GRIN Lenses use glasses containing thallium oxide. The refractive index gradient is produced by ion exchange of potassium, K+, from a molten salt bath, for thallium, Tl+ in the glass. Thallium is highly toxic making its use prohibitive in a manufacturing environment in the United States. Of the single valent ions only silver and thallium provide a large enough index change to produce high numerical aperture GRIN lenses when exchanged with alkali ions. We propose to use a silver containing glass and exchange of sodium for silver to produce the gradient.l. His work will address the problem of optimizing the composition of a silver containing glass ion exchange. The glass must have relatively high ionic mobility, be chemically resistant to the salt bath, and produce a good refractive index profile to provide high quality imaging. A series of silver containing glasses will be melted and their conductivity and chemical resistance measured. Ion exchange experiments will be performed in the successful candidate glasses and the refractive index profile will be measured and analyzed.
