Abstract: A preform for an optical element is provided which involves less amount of deformation of glass in molding, and readily improves lifetime of the mold. The present preform for molding an optical glass element 10 exhibits an almost circular shape having a predetermined diameter in top view, exhibits a flattened semicircular shape having a predetermined overall height in side view, has a concave face on the top surface such that the predetermined overall height is attained at approximately the central position of the aforementioned circular shape, and has a concave face so as to fit along the convex face of the top surface such that a space is provided on the bottom face. The under surface may be either a concave face or a convex face. Also, the top surface may be either a concave face or a convex face.

Abstract: A preform for an optical element is provided which involves less amount of deformation of glass in molding, and readily improves lifetime of the mold. The present preform for molding an optical glass element 10 exhibits an almost circular shape having a predetermined diameter in top view, exhibits a flattened semicircular shape having a predetermined overall height in side view, has a concave face on the top surface such that the predetermined overall height is attained at approximately the central position of the aforementioned circular shape, and has a concave face so as to fit along the convex face of the top surface such that a space is provided on the bottom face. The under surface may be either a concave face or a convex face. Also, the top surface may be either a concave face or a convex face.

Abstract: A preform for an optical element is provided which involves less amount of deformation of glass in molding, and readily improves lifetime of the mold. The present preform for molding an optical glass element 10 exhibits an almost circular shape having a predetermined diameter in top view, exhibits a flattened semicircular shape having a predetermined overall height in side view, has a concave face on the top surface such that the predetermined overall height is attained at approximately the central position of the aforementioned circular shape, and has a concave face so as to fit along the convex face of the top surface such that a space is provided on the bottom face. The under surface may be either a concave face or a convex face. Also, the top surface may be either a concave face or a convex face.

Abstract: A globular glass manufacturing apparatus includes: a flow nozzle to flow a molten glass in a form of continuous flow, a collection tank to collect droplet-like glass gobs deformed from the molten glass flowing in a form of continuous flow during fall. Further, the globular glass manufacturing apparatus comprises a gas nozzle to shift one or both of falling trajectories of the glass gobs neighboring above and below by blowing gas to the glass gobs or sucking the glass gobs, wherein the gas nozzle rotates in which the center is on falling trajectory of the glass gobs.

Abstract: A preform manufacture apparatus is provided which can produce a preform at low cost. A preform manufacture apparatus 1 has a first mold 20 which receives molten glass, and a second mold 50 which receives a molten glass block moved from the first mold 20. The first mold 20 has a receiving surface 20A which receives molten glass, and is dividable into two or more of split dies 30 and 40 at the receiving surface 20A.

Abstract: A preform for an optical element is provided which involves less amount of deformation of glass in molding, and readily improves lifetime of the mold. The present preform for molding an optical glass element 10 exhibits an almost circular shape having a predetermined diameter in top view, exhibits a flattened semicircular shape having a predetermined overall height in side view, has a concave face on the top surface such that the predetermined overall height is attained at approximately the central position of the aforementioned circular shape, and has a concave face so as to fit along the convex face of the top surface such that a space is provided on the bottom face. The under surface may be either a concave face or a convex face. Also, the top surface may be either a concave face or a convex face.

Abstract: A globular glass manufacturing apparatus includes: a flow nozzle to flow a molten glass in a form of continuous flow, a collection tank to collect droplet-like glass gobs deformed from the molten glass flowing in a form of continuous flow during fall. Further, the globular glass manufacturing apparatus comprises a gas nozzle to shift one or both of falling trajectories of the glass gobs neighboring above and below by blowing gas to the glass gobs or sucking the glass gobs, wherein the gas nozzle rotates in which the center is on falling trajectory of the glass gobs.

Abstract: Glass-ceramic for information recording disks have a crystalline structure suitably used for substrate materials and the like for magnetic disks and magneto-optic disks as well as have improved surface characteristics obtained by polishing the glass, and besides the base glass thereof is excellent in melting properties and moldability thereof. The base glass composition consists essentially of ingredients of SiO.sub.2 -Al.sub.2 O.sub.3 -ZnO-MgO-CaO-SrO-BaO-TiO.sub.2 system. The main crystalline phase of the glass-ceramic produced by heat-treating the base glass having a viscosity of log .eta.=3.0 poise or less at 1250.degree. C. is gahnite, a size of the crystal grain is within a range of from 50 to 1000 Angstrom, and a degree of surface roughness (Ra) of the polished glass-ceramic is within a range of from 0.5 to 9.0 Angstrom.

Abstract: An optical glass which is a SiO.sub.2 -Nb.sub.2 O.sub.5 -R'.sub.2 O (where R' is an alkali metal element)-F system of a specific composition range exhibits optical constants of a refractive index (Nd) of about 1.52-1.67 and an Abbe number (.upsilon. d) of about 32-50, is free of PbO and has an improved light transmissivity.

Abstract: An optical glass which is a SiO.sub.2 --B.sub.2 O.sub.3 --(TiO.sub.2 +ZrO.sub.2)--SrO--BaO--R'.sub.2 O system of a specific composition range exhibits optical constants of a refractive index (Nd) of 1.57-1.75 and Abbe number (.nu.d) of 30-55, is free of PbO and has improved stability against devitrification and tinting and improved chemical durability.

Abstract: An airbag restraint system for protecting a vehicle passenger in the event of a vehicle serious collision from the lateral side direction of the vehicle. The system comprises an airbag which is disposed at each of doors and a center console located at a center portion between right and left seats. An acceleration sensor is disposed at each of lateral sides of the vehicle to detect side directional impact to the vehicle. When the vehicle is crashed at the one lateral side of the vehicle, the airbags at an impacted side and the center airbag are inflated. Similarly, when the vehicle is crashed at the the other lateral side of the vehicle, the impacted side airbags and the center airbag are inflated.