Hoya Glass Works, Ltd.

Hoya Corporation

Kenji Nakagawa

Tetsuro Izumitani

Yoshiyuki Asahara

Kunimitsu Kobayashi

Hiroyuki Sakai

Masahiro Yoshida

Isao Masuda

Shin Nakayama

Shigeaki Omi

Toshihiro Kasuga

Seiichi Shingaki

Ko Itaya

Masaaki Osagawa

Susumu Horikawa

Yoshito Nogami

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.

Process for producing transparent glass product having refractive index

A high-strength glass-ceramic containing apatite crystals or .beta.-tricalcium phosphate crystals, and anorthite crystals, and a process for producing the same are disclosed. The glass-ceramic has an excellent biocompatibility and is useful as an implant material such as an artificial dental root and an artificial bone.

High-strength glass-ceramic containing anorthite crystals and process

A high strength glass-ceramic containing apatite and alkaline earth metal silicate (diopside/forsterite/akermanite) crystals having an excellent affinity for a living body and a process for producing the same are disclosed. The glass-ceramic is useful as an implant material such as an artificial dental root and an artificial bone.

High strength glass-ceramic containing apatite and alkaline earth metal

An alkali-free glass composition for a photoetching mask is described, which comprises, all by mol, 55 to 65% SiO.sub.2, 7 to 11% Al.sub.2 O.sub.3, 1 to 11% PbO, 7 to 20% CaO, 3 to 13% MgO, 3 to 13% ZnO, 0 to 3% ZrO.sub.2, 0 to 3% F.sub.2, 0 to 5% As.sub.2 O.sub.3, and 0 to 5% Sb.sub.2 O.sub.3. This glass is free from defects such as pinholes, has a relatively low coefficient of thermal expansion and contains no air bubbles, and a photoetching mask composed of the glass composition.

Alkali-free glass for photoetching mask

An optical fiber comprising a core glass and a cladding glass therearound, wherein at least the core glass contains GeO.sub.2 as an additive to increase the refractive index with respect to the cladding glass. The fiber glass is prepared by heat treating a starting glass to separate out a B.sub.2 O.sub.3 --Na.sub.2 O-rich phase for subsequent acid leaching, and by sintering a residual glass with low concentrations of light absorbing impurities. Ingredients of the starting glass in weight percent are as follows:

Optical fiber

A sealing method for a laser glass which provides a high bonding strength comprising applying a powder mixture of (1) a low melting glass for sealing a glass laser and (2) a glass having a higher melting point and lower expansion coefficient than those of the low melting glass, to a laser glass and welding the powder mixture to the laser glass by heating.

Sealing method for laser glass

A process for heat-bonding optical fibers comprising aligning a number of optical fibers in a mould with at least one of whose end surfaces is open and with end members slidable towards the inside of the mould from positions at which the end surfaces are open whereby a gas present among the optical fibers can be discharged, heating the optical fibers and evacuating the gas in the mould, closing the open end surfaces and applying pressure to the optical fibers through a press member and the end members, thereby heat-bonding the optical fibers; and an apparatus for heat-bonding optical fibers, comprising a mould with at least one of whose end surfaces is open, and including a press member as a wall of the mould, at least one end member provided for the end surfaces of the mould, and being capable of sliding inwardly along inclined surfaces of the press member upon application of a presssure on the press member.

Apparatus for heat-bonding optical fibers

A SiO.sub.2 -Al.sub.2 O.sub.3 -Na.sub.2 O-Li.sub.2 O glass which can be strengthened in a short time, typically in less than about thirty minutes, by an alkali metal ion exchange method to produce a high strength glass having an improved compressive surface layer of relatively large thickness can be obtained by substituting Li.sub.2 O for a portion of Na.sub.2 O content in a glass consisting essentially of SiO.sub.2, Al.sub.2 O.sub.3, Na.sub.2 O, Li.sub.2 O and F.sub.2.

High strength glass made by ion exchange

A process for producing a gas tight light transmitting optical fiber plate comprising arranging the optical fibers or bundles of the optical fibers in a die, heating and compressing the optical fibers at a temperature of between the transition point of the glass of the optical fibers and the softening point of the glass of the optical fibers thereby to weld the optical fibers together, and maintaining the welded optical fibers within that temperature range at a pressure higher than the pressure during the heating period which is sufficient to cause the shrinkage of voids by the surface tension of the optical fibers.

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Tokorozawa, Japan

Kenji Nakagawa