A molding device and a molding method for an optical fiber preform are provided. The molding device includes a rotating mechanism, an extrusion mechanism, and a cylinder mold that is of a cylindrical structure with two ends each having an opening. After a hollow cladding sleeve is obtained by rotating the cylinder mold through the rotating mechanism, a molten core glass is then reversely extruded into the cladding sleeve in the cylinder mold from bottom to top by the extrusion mechanism to prepare the optical fiber preform.

A molding device and a molding method for an optical fiber preform are provided. The molding device includes a rotating mechanism, an extrusion mechanism, and a cylinder mold that is of a cylindrical structure with two ends each having an opening. After a hollow cladding sleeve is obtained by rotating the cylinder mold through the rotating mechanism, a molten core glass is then reversely extruded into the cladding sleeve in the cylinder mold from bottom to top by the extrusion mechanism to prepare the optical fiber preform.

A glass composition, a macrocomposite, and methods of forming the macrocomposite including dispersing or immersing a metal in a glass. Preferably, the macrocomposite does not include an organic resin, an adhesive, or a polymer.

A method for manufacturing an optical element out of glass comprises placing a blank made of glass on an annular contact face of a supporting body having a hollow cross section. The blank is heated on the supporting body in a cavity of a protective cap that is arranged in a furnace cavity, such that a temperature gradient is established in the blank in such a way that the blank is cooler inside than on an outside region. The blank is press molded to form the optical element.

Photosensitive lithium zinc aluminosilicate glasses that can be selectively irradiated and cerammed to provide patterned regions of glass and lithium-based glass ceramic, and composite glass articles made from such glasses and glass ceramics are provided. The lithium zinc aluminosilicate glass can be negatively photosensitive or positively photosensitive to radiation having a wavelength in a range from about 248 nm to about 360 nm.

Photosensitive lithium zinc aluminosilicate glasses that can be selectively irradiated and cerammed to provide patterned regions of glass and lithium-based glass ceramic, and composite glass articles made from such glasses and glass ceramics are provided. The lithium zinc aluminosilicate glass can be negatively photosensitive or positively photosensitive to radiation having a wavelength in a range from about 248 nm to about 360 nm.

A method of controlling compaction including obtaining a plurality of sets of process conditions for a plurality of glass ribbons, measuring a compaction value for a glass sheet cut from each glass ribbon of the plurality of glass ribbons, correlating the compaction to the process conditions. The method further includes selecting a predetermined cooling curve including a plurality of cooling rates, modifying the cooling curve by varying cooling rates of the plurality of cooling rates, calculating a predicted compaction value for a glass sheet cut from a glass ribbon drawn using the modified cooling curve, and repeating the modification and predicting until compaction is minimized.

A glass-ceramic comprising, in weight percent on an oxide basis, of 50 to 70% SiO.sub.2, 0 to 20% Al.sub.2O.sub.3, 12 to 23% MgO, 0 to 4% Li.sub.2O, 0 to 10% Na.sub.2O, 0 to 10% K.sub.2O, 0 to 5% ZrO.sub.2, and 2 to 12% F, wherein the predominant crystalline phase of said glass-ceramic is a trisilicic mica, a tetrasilicic mica, or a mica solid solution between trisilicic and tetrasilicic, and wherein the total of Na.sub.2O+Li.sub.2O is at least 2 wt. %; wherein the glass-ceramic can be ion-exchanged.

A glass-ceramic comprising, in weight percent on an oxide basis, of 50 to 70% SiO.sub.2, 0 to 20% Al.sub.2O.sub.3, 12 to 23% MgO, 0 to 4% Li.sub.2O, 0 to 10% Na.sub.2O, 0 to 10% K.sub.2O, 0 to 5% ZrO.sub.2, and 2 to 12% F, wherein the predominant crystalline phase of said glass-ceramic is a trisilicic mica, a tetrasilicic mica, or a mica solid solution between trisilicic and tetrasilicic, and wherein the total of Na.sub.2O+Li.sub.2O is at least 2 wt. %; wherein the glass-ceramic can be ion-exchanged.

A chemically strengthened bioactive glass-ceramic composition as defined herein. Also disclosed are methods of making and using the disclosed compositions.