To provide a flat plate lens, having a large numerical aperture by making Ag diffuse as an ingredient for increasing the refraction index to a glass substrate which contains Li and is superior in chemical durability, and to provide a method of manufacturing the same.
The flat plate lens is formed by diffusing a refraction index-increasing component inside the substrate of the flat plate into a hemispherical shape or a semi cylindrical shape by ion exchange method, wherein the refraction index increasing component is Ag, and the glass substrate contains at least Li as a alkaline metal component to be ion exchanged with Ag. Furthermore, when a radial distance r, a distance from the center of the hemispherical shape or of the semicylindrical shape and the refraction index n are considered as coordinate axes of an orthogonal coordinates, wherein the distribution curve of the refraction index n regarding the distance r is made into a convex shape directed toward the positive direction of the refraction index n axis.
YOSHII NARIKAZU
SAKAGUCHI KOICHI
