Asahi Glass Company, Limited

Jun Sasai

Naoki Sugimoto

Syuji Matsumoto

Kenji Imakita

Hiroyuki Ohkawa

Tetsuya Nakashima

Yuichi Suzuki

Yuki Kondo

Tomoyuki Kobayashi

Satoru Tomeno

Takeshi Shimazaki

The present invention relates to a float glass for chemical strengthening, containing a bottom surface coming into contact with a molten metal at the time of forming and a top surface opposing the bottom surface, in which a difference &#x394;(N&#x2014;NaO) determined by subtracting a square of a normalized NaO surface concentration of the bottom surface which is a value obtained by dividing an NaO concentration in the bottom surface by an NaO concentration at a depth position of 100 &#x3bc;m therefrom, from a square of a normalized NaO surface concentration of the top surface which is a value obtained by dividing an NaO concentration in the top surface by an NaO concentration at a depth position of 100 &#x3bc;m therefrom, is 0.040 or less.

Float glass for chemical strengthening

An object of the invention is to provide an optical glass for precision press having optical properties of a high refractive index and a low dispersion property and having a low molding temperature, a high devitrification resistance, an excellent molding property, and a small specific gravity. The optical glass of the invention contains, in terms of % by mass on the basis of oxides, respective components of BO: 10 to 20%, SiO: 0.5 to 12%, LaO: 25 to 50%, GdO: 0 to 20%, YO: 0 to 20%, provided that LaO+GdO+YO: 35 to 60%, ZnO: 5 to 20%, LiO: 0.2 to 3%, ZrO: 0 to 0.5%, TaO: 3 to 18% and WO: 3 to 20%, and has optical constants of a refractive index nof 1.84 to 1.86 and an Abbe number vof 37 to 42 and a glass transition point (T) of 630&#xb0; C. or lower.

Optical glass and preforms for precision press molding and optical elements made by using the glass

To provide a production process capable of making the transmittance of an optical glass element obtainable by press-molding a TeO-containing glass high. A process for producing an optical glass element, which comprises press-molding a TeO-containing glass, wherein the press-molding is carried out in an atmosphere in which the nitrogen partial pressure is at most 10Pa. The above process for producing an optical glass element, wherein the face of a mold for the press-molding to be in contact with the glass is made of carbon. The above process for producing an optical glass element, wherein the molded glass obtained by the press-molding is held in an oxygen-containing atmosphere at a temperature within a range of at least a temperature lower by 50&#xb0; C. than the glass transition point of the TeO-containing glass and at most the softening point of the glass.

Process for producing optical glass element

This invention provides an optical glass including, by mass %: 30 to 40% of BO; 2.5 to 6% of LiO; 10 to 17% of ZnO; 12 to 22% of LaO; 15 to 25% of GdO; 0 to 5% of SiO; 0 to 5% of BiO; 0 to 15% of AlO; 0 to 3% of ZrO; 0 to 5% of WO; 0 to 5% of TaO; 0 to 3% of TiO; 0 to 5% of YO; and 0 to 5% of MgO+CaO+SrO+BaO.

Optical glass

The present invention provides an optical glass including, by mass %: 46 to 70 of BO; 3 to 10 of LiO; 5 to 15 of YO; 0 to 46 of SiO: 0 to 20 of AlO: 0 to 40 of MgO+CaO+SrO+BaO; 0 to 30 of LaO; and 0 to 10 of ZrO+TiO+GdO.

An optical glass which has an internal transmittance to a light having a wavelength of 400 nm being at least 90% as calculated in a thickness of 1 mm and which contains at least 25 mol % of BOand from 0.1 to 20 mol % of TeO. The above optical glass which contains LaO. The above optical glass wherein the glass transition point &#x2266;650&#xb0; C. and the refractive index at 633 nm&#x2267;1.70. A process for producing an optical element made of the above optical glass, which comprises dropping the optical glass in a molten state from a flow outlet of a flow out pipe made of a platinum alloy to form a preform and subjecting it to precision press-molding.

Optical glass and process for producing optical element

To provide an optical glass which has a high transmittance and a high refractive index and shows little decrease in the transmitted light intensity when continuously irradiated with a blue-violet laser diode light, and which is less prone to a higher melting temperature and exhibits chemical durability being not low. An optical glass consisting essentially of, as represented by mol %, from 35 to 54% of TeO, from 0 to 10% of GeO, from 5 to 30% of BO, from 0 to 15% of GaO, from 0 to 8% of BiO, from 3 to 20% of ZnO, from 0 to 10% of MgO+CaO+SrO+BaO, from 1 to 10% of YO+LaO+GdO, from 0 to 5% of TaO+NbO, from 0 to 1.8% of TiO, and from 0 to 6% of LiO+NaO+KO+RbO+CsO. A lens made of such an optical glass.

Growing community of inventors

Tokyo, Japan

Jun Sasai