PURPOSE: To obtain a distributed index type optical element which is three- dimensionally different in shape by allowing a light absorber part having exchangeable ions and coloring part to co-exist at least in a part of the surface of a transparent dielectric part having a refractive index distribution.
CONSTITUTION: The cylindrical light absorber glass 4 having the exchangeable ions and coloring component is disposed on the outside circumference of rod- shaped core glass 3. Said glass is then heated in an electric furnace 5 and is pulled by pulling rollers 6, by which the core glass 3 and the light absorber glass 4 are welded and integrated in contact with each other and a double- layered glass rod 7 is obtd. This double-walled glass rod 7 is cut to a suitable length and is immersed in a fused salt contg. the exchangeable ions so that the exchange of the exchangeable ions in the rod 7 and the exchangeable ions in the fused salt is executed. The double-layered rod after the ion exchange constitutes the rod lens having a transparent core part 8 having the refractive index distribution and the light absorber layer 9. Various kinds of the distributed index type optical elements which have excellent optical characteristics and high strength and are different in the shapes of the light absorber part are thereby easily obtd.
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