A method of readily producing a gradient optical element having
infrared absorbing ability by easily forming a
refractive index distribution in a desired portion of a glass substrate having
infrared absorbing ability without requiring a specific treatment
atmosphere nor using a
molten salt.More specifically, the present invention provides a method for producing a gradient-index optical element having
infrared absorbing ability, the method comprising applying a paste containing an organic resin, an
organic solvent, and at least one compound selected from the group consisting of
lithium compounds,
potassium compounds,
rubidium compounds, cesium compounds, silver compounds,
copper compounds, and
thallium compounds onto a glass substrate containing an
alkali metal component, at least one member selected from the group consisting of iron,
copper,
cobalt and
vanadium, and over 3 wt. % of iron, when contained singly among iron,
copper,
cobalt and
vanadium, on an Fe2O3 basis, taking the total weight of the glass as 100 wt. %, and heating the glass substrate at a temperature below the
softening temperature of the glass substrate.