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US 6,844,279 B2Granted
Optical glass, press-molding preform and optical part
AssigneeHoya Corporation
InventorsKazutaka Hayashi, Yasuhiro Fujiwara, Zou Xuelu
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AssigneeHoya Corporation
InventorsKazutaka Hayashi, Yasuhiro Fujiwara, Zou Xuelu
Estimating the term…
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 B2O3, La2O3, Gd2O3 and 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 (νd) of 45 to 55 and a glass transition temperature (Tg) of 630° C. or lower and having a viscosity of at least 0.6 Pa·s at its liquidus temperature, and an optical glass comprising, by mol %, 45 to 65% of B2O3, 5 to 22% of La2O3, 1 to 20% of Gd2O3, provided that the total content of La2O3 and Gd2O3 is 14 to 30%, 5 to 30% of ZnO, 0 to 10% of SiO2, 0 to 6.5% of ZrO2 and 0 to 1% of Sb2O3, substantially containing none of lead and fluorine, and having a refractive index (nd) of 1.72 to 1.83 and an Abbe's number (νd) of 45 to 55.
A press-molding preform made of an optical glass comprising B2O3, La2O3, Gd2O3 and ZnO as essential components, providing the total content of La2O3 and Gd2O3 is at least 15 mol %, substantially containing none of lead and fluorine, having a refractive index (nd) of 1.72 to 1.83, an Abbe's (νd) of 45 to 55 and a glass transition temperature (Tg) of 630° C. or lower and having a viscosity of at least 0.6 Pa·s at its liquidus temperature.
A press-molding preform made from optical glass comprising, by mol %, 45 to 65% of B2O3, 5 to 22% of La2O3, 1 to 20% of Gd2O3, provided that the total content of La2O3 and Gd2O3 is 15 to 30%, 5 to 30% of ZnO, 0 to 10% of SiO2, 0 to 6.5% of ZrO2 and 0 to 1% of Sb2O3, substantially containing none of lead and fluorine, and having a refractive index (nd) of 1.72 to 1.83 and Abbe's number (νd) of 45 to 55.
A process for the preparation of a press-molding preform, which comprises preparing a glass gob from a predetermined amount of a molten glass and shaping the glass gob into a press-molding preform made of an optical glass comprising B2O3, La2O3, Gd2O3 and ZnO as essential components, providing the total content of La2O3 and Gd2O3 is at least 15 mol %, substantially containing none of lead and fluorine, having a refractive index (nd) of 1.72 to 1.83, an Abbe's number (νd) of 45 to 55 and a glass transition temperature (Tg) of 630° C. or lower and having a viscosity of at least 0.6 Pa·s at its liquidus temperature.
A process for the preparation of a press-molding preform, which comprises preparing a glass gob from a predetermined amount of a molten glass and shaping the glass gob into a press-molding preform made of an optical glass comprising, by mol %, 45 to 65% of B2O3, 5 to 22% of La2O3, 1 to 20% of Gd2O3, provided that the total content of La2O3 and Gd2O3 is 15 to 30%, 5 to 30% of ZnO, 0 to 10% of SiO2, 0 to 6.5% of ZrO2 and 0 to 1% of Sb2O3, substantially containing none of lead and fluorine, and having a refractive index (nd) of 1.72 to 1.83 and an Abbe's number (νd) of 45 to 55.
Dependencies are inferred from the claim text.