Abstract: A gradient index-type optical device produced by the ion exchange process, comprising: a transparent dielectric body having a refractive index distribution, and a refractive index distribution-adjusting portion disposed on at least a part of the transparent dielectric body. Because of the presence of the refractive-index distribution, the ion-exchange speed therethrough is controlled to provide a controlled refractive index distribution in the transparent dielectric body. As a result, a gradient index-type optical device having a large refractive index factor (g value) without substantial increase in aberration.

Abstract: A gradient index-type optical device is produced by the ion exchange process. First, a transparent dielectric body contacting an ion to be exchanged is provided with a light-absorbing portion containing also an ion to be exchanged and a coloring component at at least a part of the surface thereof. The transparent dielectric is soaked in or caused to contact a molten salt containing an ion providing a refracted index distribution for ion exchange. In the gradient index-transparent dielectric thus produced, the light-absorbing portion can have a refractive index continuous with that of the transparent dielectric body and a thermal expansion coefficient equal to or smaller than that of the transparent dielectric body, so that flare at the boundary and the stress fragility are alleviated. The optical device can also have a good size accuracy.

Abstract: A vitreous film containing, e.g., 30-90 wt. % of Sn, 1-20 wt. % of P, 0.1-20 wt. % of Pb, 2-30 wt. % of 0 and 5-35 wt. % of F is formed by vapor deposition on a substrate such as glass, metal, plastic or ceramic. A light-absorbing substance can be incorporated in the vitreous film to provide a recording layer for a heat-mode optical recording medium capable of causing decoloration or formation of pits on irradiation with a laser beam.

Abstract: Refractive index distribution lenses may be made by forming refractive index distribution patterns in surfaces of two substrates. The patterns in the two substrates are made to be matching. Then, these surfaces of the two substrates are placed together with the patterns in the substrates coinciding. If the refractive index distribution patterns in the surfaces form semicylindrical lenses with parallel axes, the substrates may be put together so that the axes of the lenses in one substrate coincide with corresponding axes of semicylindrical lenses in the other substrate to form a rod lens array. If the refractive index distribution patterns in the two substrates are constant in directions parallel to the surfaces of these substrates but vary in the direction perpendicular to the surfaces, the surfaces of these substrates may be put together to form a slab lens.

Abstract: A process for producing a transparent glass product having a refractive index gradient by the molecular stuffing method is described. A thallium compound is used as a dopant and, after a concentration gradient of the thallium dopant is formed, the porous glass product is heated up to the temperature region of 350.degree. to 550.degree. C. at a temperature-rising rate of 25.degree. to 150.degree. C./hour in a reducing gas atmosphere and then heat treated above 550.degree. C. in an inert gas atmosphere to collapse micropores in the porous glass product, thereby obtaining a glass product having a refractive index gradient which is transparent and free of light-scattering and coloration. The glass product is suitable as materials (preforms) for optical fibers or materials for rod-shaped lenses, particularly rod-shaped microlenses for microlens arrays and microlenses for coupling an optical fiber and a light source.

Abstract: A process for producing a glass product having .DELTA.n, the difference between the central and peripheral portions of the glass, greater than 0.04. This process utilizes a porous glass body which is produced via a phase separation technique. A dopant selected from the group consisting of (1) TlNO.sub.3, (2) TlNO.sub.3 and an alkali metal compound and (3) TlNO.sub.3, Pb(NO.sub.3).sub.2 and an alkali metal compound is then permeated into the micropores of the porous glass product. A concentration gradient of the dopant is then formed by leaching out a portion of the dopant from the micropores. After the dopant is solidified in the mircopores, the porous glass product is dried. A heat-treatment step then serves to collapse the micropores. A glass product having a gradient of refractive indices is therby obtained.

Abstract: A process for the production of a slab-shaped lens having a gradient of refractive index only in the direction of thickness thereof is described, comprising stuffing a solution of dopant into micropores of a plate-shaped porous glass product with or without a heat-resistant film covered on both side surfaces thereof; unstuffing a part of the dopant to form a gradient of dopant concentration in the glass product; precipitating the dopant in the micropores; drying the porous glass product to evaporate the solvent remaining in the micropores; collapsing the micropores by applying a heat treatment to form a gradient of refractive index in the plate-shaped glass product; and when the side surfaces are not covered with the film, cutting off both side end portions of the plate-shaped glass product.

Abstract: A process for producing a glass product having .DELTA.n, the difference between the central and peripheral portions of the glass, greater than 0.04. This process utilizes a porous glass body which is produced via a phase separation technique. A dopant selected from the group consisting of (1) TlNO.sub.3, (2) TlNO.sub.3 and an alkali metal compound and (3) TlNO.sub.3, Pb(NO.sub.3).sub.2 and an alkali metal compound is then permeated into the micropores of the porous glass product. A concentration gradient of the dopant is then formed by leaching out a portion of the dopant from the micropores. After the dopant is solidified in the micropores, the porous glass product is dried. A heat-treatment step then serves to collapse the micropores. A glass product having a gradient of refractive indices is thereby obtained.