Gradient-index rod lenses with a parabolic-index profile have been fabricated by a double Na-Ag ion-exchange process, and their optical characteristics have been evaluated. The numerical aperture and minimum focused spot diameter of the 2-mm diam rod lens were 0.58 and 2.5 microm for lambda = 0.63 microm, respectively. Because of the high diffusing rate for Ag ions, this technique offers the possibility of making large-sized (larger than 10 mm-diam) rod lenses for photographic uses.

No abstract

No abstract

Gradient index (GRIN) rod lenses with parabolic index profiles have a variety of application including imaging systems and optical communication systems.1) There are a number of techniques that could be used for making these radial gradients in the glass. Ion exchange is probably the most widely and successfully used technique in the fabrication of GRIN rod lens for optical communication applications, because it is the simplest in terms of instrumentation and control. In conventional ion exchange techniques, T1 ions in a glass rod are exchanged for K or Na ions in a molten salt.2,3) There appears to be some problems in T1 ions, namely high toxicity and low diffusion rate in the glass. Ag ions also offer great potential for making large numerical aperture lenses because of their high refractive index in the glass. However, silver oxide cannot be introduced into the glass in significant quantities by melting.

Recently there has been interest in the development of processes for fabricating gradient index (GRIN) lenses, the profile of which is expressed by Here, n0 is the index on the center axis, r is the distance from the center axis and g is the focusing factor. New process, termed "molecular stuffing process" was currently developed for fabricating radially distributed index profiles.[1,2]. This process offers a possibility of making large sized lenses, but there have been no accurate measurements and analyses of their index profiles and aberration characteristics. The purpose of this study is to find the optimum fabrication conditions for parabolic profiles and to evaluate the optical characteristics of lenses made by the molecular stuffing technique.