Abstract: A method for manufacturing a glass is provided, comprising converting a porous body to a multi-component glass, wherein a porous body containing at least one metal component in the form of a metal salt is immersed in a solution containing at least one compound selected from the group consisting of an acid, an ammonium salt and an alkylammonium salt to precipitate the metal salt as microcrystals in the pore. Also, a method for manufacturing a glass for use as a gradient index optical element is provided, comprising converting a porous body to a multi-component glass, wherein a porous body containing at least one metal component in the form of a metal salt is immersed in a solution containing a salt of a metal component different from the above-mentioned at least one component and at least one compound selected from the group consisting of an acid and a salt to provide the metal components with concentration distributions.

Abstract: A gradient index optical element for use in optical lens such as a camera or microscope is disclosed. The optical element comprises at least one of first metal dopants selected from La, Zr, Sn, In, Y, Ge, Zn, Ba, Ca, As, Sr, Ga and Gd distributed in solvent with a slope, and at least one of second metal dopants selected from Nb, Ta, Ti, Bi, Pb, Sb, Zr, Sn, In, Y and Tl, which is distributed equally in the solvent so as to satisfy following equation as absolute amount;.vertline..DELTA.C.sub.f /.DELTA.C.sub.g .vertline..multidot.100.ltoreq.5wherein .DELTA.C.sub.g is a difference between maximum value and minimum value of equivalent value of metal oxides of the first metal doping and .DELTA.C.sub.f is a difference between maximum value and minimum value of equivalent value of metal oxides of the second metal doping.

Abstract: A gradient index optical element has at least one first metal dopant selected from the group consisting of La, Y, Ga, In, Ge, Sn, Zn, Zr, Ba, Ca, As, Sr, Gd and Be distributed at a concentration gradient in a glass medium. The concentration gradient of the first metal dopant defines a slope having a direction. At least one second metal dopant different from the first metal dopant and selected from the group consisting of Bi, Sb, Nb, Ti, Ta, Pb, Tl, Zr, In, Sn, Y, Ba, Ca and Sr is distributed at a concentration gradient in the glass medium. The concentration gradient of the second metal dopant defines a slope smaller than the slope of the concentration gradient of the first metal dopant. The slope of the concentration gradient of the second metal dopant is in the same direction as the slope of the concentration gradient of the first metal dopant.

Abstract: A method of manufacturing distributed index optical elements is disclosed. The method comprises a step of preparing silica sol including at least one of metal dopants, a step of dipping, after subjecting the silica sol to a gelling treatment, the silica gel in an elute into which a part of metal constituents other than silicon including in the gel is selectively eluted, and a step of drying and sintering the silica gel.