Hoya Corporation

Zou Xuelu

Yasuhiro Fujiwara

Kazutaka Hayashi

Hiroyuki Sakai

Shinichiro Hirota

A high-refractivity low-dispersion optical glass that gives press-molding preforms excellent in high-temperature shapability and suitable for precision press-molding, including an optical glass comprising BO, LaO, GdOand ZnO as essential components, substantially containing none of lead and fluorine, having a refractive index (nd) of 1.72 to 1.83, an Abbe's number (&#x3bd;d) of 45 to 55 and a glass transition temperature (Tg) of 630&#xb0; C. or lower and having a viscosity of at least 0.6 Pa&#xb7;s at its liquidus temperature, and an optical glass comprising, by mol %, 45 to 65% of BO, 5 to 22% of LaO, 1 to 20% of GdO, provided that the total content of LaOand GdOis 14 to 30%, 5 to 30% of ZnO, 0 to 10% of SiO, 0 to 6.5% of ZrOand 0 to 1% of SbO, substantially containing none of lead and fluorine, and having a refractive index (nd) of 1.72 to 1.83 and an Abbe's number (&#x3bd;d) of 45 to 55.

Optical glass, press-molding preform and optical part

Disclosed is a method of manufacturing ultraprecise lenses, including aspherical lenses, not requiring grinding or polishing after press molding. The method comprises heating a glass material to a temperature corresponding to a glass viscosity of from 10to 10dPaS so that the glass material is softened, and press molding the glass material with the pressing molds which are heated to a temperature corresponding to a glass viscosity of from 10to 10dPaS. Provided that the glass material is not heated to a temperature as high as that corresponding to a glass viscosity of 10dPaS when the pressing mold is heated to a temperature corresponding to a glass viscosity of 10and that the glass material is not heated to a temperature as low as that corresponding to a glass viscosity of 10dPaS when the pressing mold is heated to a temperature corresponding to a glass viscosity of 10dPaS. The glass material to be molded comprises at least one selected from the group consisting of NbO, WO, and TiOand has a refractive index nd of greater than or equal to 1.65, an Abb&#xe8; number (&#x3bd; d) of less than or equal to 35, and a sag point (Ts) of less than or equal to 570&#xb0; C. Each of the pressing molds comprises a film comprising carbon on a molding surface.

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Tokyo, Japan

Zou Xuelu