Provided is a glass composition that exhibits greater Faraday effect than ever before. A glass composition contains 48% or more of Tb.sub.2O.sub.3 (exclusive of 48%) in % by mole.

A tool for local cooling by contact of a glass sheet at a temperature higher than 450° C., known as a contact tool, includes a contact face suitable for coming into contact with the glass sheet, the tool including an internal pipe for the circulation of a coolant, in particular air. The tool is used in a device for bending and/or cooling a glass sheet, in particular individual, the tool coming into contact with the glass sheet while it is held by a bending tool or by a cooling frame after bending. A compression zone is created that is capable of being drilled to form an edge having compressive stresses.

Provided is a magneto-optic element that enables easy size reduction of an optical isolator. A magneto-optic element is formed of two or more magnetic members joined together.

An apparatus (100) for making glass tubing (200) of a desired non-circular cross-sectional profile (cf FIG. 3) includes a mandrel (101) adapted for positioning proximate heat-softened tubing. The mandrel (101) has a nose (102) and a nozzle section (120) with a chosen profile that will define a final cross-sectional profile of the tubing. The nozzle section (120) has a feed chamber (140) for receiving a gas from a source (207) and a porous and/or foraminous circumferential surface (132,134) through which the gas can be discharged to an exterior of the mandrel. The gas discharges to the exterior of the mandrel, forming a film of pressurized gas in the gap (314, 318) between the porous circumferential surface (132,134) and the heat-softened tubing (200). A method of forming tubing having a non-circular cross-sectional profile using the apparatus is also provided. A glass sleeve made from the reshaped or formed tubing is also disclosed: a monolithic sleeve made of parallel, opposite, flat and smooth front and back covers for use in an electronic device (cf FIG. 13). Some glass-ceramic materials may also be suitable for the tubing, such as transparent beta spodumene.

An apparatus (100) for making glass tubing (200) of a desired non-circular cross-sectional profile (cf FIG. 3) includes a mandrel (101) adapted for positioning proximate heat-softened tubing. The mandrel (101) has a nose (102) and a nozzle section (120) with a chosen profile that will define a final cross-sectional profile of the tubing. The nozzle section (120) has a feed chamber (140) for receiving a gas from a source (207) and a porous and/or foraminous circumferential surface (132,134) through which the gas can be discharged to an exterior of the mandrel. The gas discharges to the exterior of the mandrel, forming a film of pressurized gas in the gap (314, 318) between the porous circumferential surface (132,134) and the heat-softened tubing (200). A method of forming tubing having a non-circular cross-sectional profile using the apparatus is also provided. A glass sleeve made from the reshaped or formed tubing is also disclosed: a monolithic sleeve made of parallel, opposite, flat and smooth front and back covers for use in an electronic device (cf FIG. 13). Some glass-ceramic materials may also be suitable for the tubing, such as transparent beta spodumene.

Provided is a glass composition that exhibits greater Faraday effect than ever before. A glass composition contains 48% or more of Tb.sub.2O.sub.3 (exclusive of 48%) in % by mole.

Provided is optical glass containing, in terms of mol % of cations: 10 to 60% of a La.sup.3+ component; more than 0% and up to 75% of a Ga.sup.3+ component; and 5 to 75% of a Nb.sup.5+ component, in which a total amount of the La.sup.3+ component, Ga.sup.3+ component, and Nb.sup.5+ component is 60 to 100%.

An optical glass includes, in terms of mol % of cations, a total amount of La.sup.3+, Y.sup.3+, and Gd.sup.3+ components falling within a range of from 5% to 65% and a total amount of Zr.sup.4+, Hf.sup.4+, and Ta.sup.5+ components failing within a range of from 5% to 65%, and a relationship expressed in Expression (1) given below is satisfied. (La.sup.3++Y.sup.3++Gd.sup.3+)×(Zr.sup.4+ Hf.sup.4++Ta.sup.3+)≥400(%).sup.2.

Provided is a method that can manufacture a glass material having excellent homogeneity by containerless levitation. With a block (12) of glass raw material held levitated above a forming surface (10a) of a forming die (10) by jetting gas through a gas jet hole (10b) opening on the forming surface (10a), the block (12) of glass raw material is heated and melted by irradiation with laser beam, thus obtaining a molten glass, and the molten glass is then cooled to obtain a glass material. Control gas is jetted to the block (12) of glass raw material along a direction different from a direction of jetting of the levitation gas for use in levitating the block (12) of glass raw material or the molten glass.

Provided is a method that can manufacture a glass material having excellent homogeneity by containerless levitation. With a block (12) of glass raw material held levitated above a forming surface (10a) of a forming die (10) by jetting gas through a gas jet hole (10b) opening on the forming surface (10a), the block (12) of glass raw material is heated and melted by irradiation with laser beam, thus obtaining a molten glass, and the molten glass is then cooled to obtain a glass material. Control gas is jetted to the block (12) of glass raw material along a direction different from a direction of jetting of the levitation gas for use in levitating the block (12) of glass raw material or the molten glass.