Optical glass
AssigneeKabushiki Kaisha Ohara
InventorsJunko Suzuki, Michiko Ogino, Masahiro Onozawa
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Abstract
There is provided an optical glass with a high refractive index and a low dispersion having a refractive index (nd) of not less than 1.75 and an Abbe's number (νd) of not less than 35 where the image formation characteristic is hardly affected by changes in temperature of the using environment. SiO2, B2O3 and La2O3 are contained as essential components and the ratio of the constituting components are adjusted whereby an optical glass in which a product of α and β where α is an average linear expansion coefficient at −30 to +70° C. and β is an optical elasticity constant at the wavelength of 546.1 nm is not more than 130×10−12° C.−1×nm×cm−1×Pa−1 is able to be achieved.
Claims16
An optical glass comprising, by mass on oxide basis:
- SiO2 more than 1.0% and less than 12.0%,
- B2O3 8.0 to 35.0%, the ratio of SiO2/B2O3 being more than 0 and less than 0.6, and
- La2O3 25.0 to 50.0%,
- wherein the product of α and β, where α is an average linear expansion coefficient within −30° C. to +70° C. and β is an optical elasticity constant at the wavelength of 546.1 nm, is not more than 130×10−12° C.−1×nm×cm−1×Pa−1.
An optical glass, comprising, by mass on oxide basis:
- more than 1.0% and less than 10.0% of SiO2,
- 15.0 to 28.0% of B2O3,
- 28.0 to 35.0% of La2O3,
- 25.0 to 35.0% of Gd2O3,
- 5.0 to 9.0% of ZrO2 and
- 0.1 to less than 2.0% of ZnO
- 0.0 to 6.0% of Ta2O5,
- 0.0 to 5.0% of Nb2O5,
- 0.0 to 1.0% of Sb2O3, and
- 0.0 to less than 1.0% by mass of Al2O3,
- wherein the sum of ZrO2+Nb2O5 is more than 5.0% to less than 13.0%, the glass has optical constants within such ranges that the refractive index (nd) is 1.78 to 1.83 and the Abbe's number (νd) is 44 to 48 and the product of α and β, where α is an average linear expansion coefficient within −30° C. to +70° C., and β is an optical elasticity constant at the wavelength of 546.1 nm, is not more than 90×1012° C.−1×nm×cm−1×Pa−1.
Dependencies are inferred from the claim text.