Optical glass
AssigneeKabushiki Kaisha Ohara
InventorSusumu UEHARA
Life of this patent
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Abstract
An optical glass has optical constants of a refractive index (nd) within a range from 1.73 to less than 1.80 and an Abbe number (νd) within a range from 43 to 55, comprises SiO2, B2O3, Y2O3, La2O3, ZnO and Li2O as essential components, is substantially free of lead component, arsenic component and fluorine component, has a ratio of SiO2/B2O3 of 0.30 to 1.55 and a ratio of Y2O3/La2O3 of 0.15 to 1.00, and has a glass transition temperature (Tg) of 620° C. or below.
Claims10
An optical glass having optical constants of a refractive index (nd) within a range from 1.73 to less than 1.80 and an Abbe number (νd) within a range from 43 to 55, comprising SiO2, B2O3, Y2O3, La2O3, ZnO and Li2O as essential components, being substantially free of lead component, arsenic component and fluorine component, having a ratio of SiO2/B2O3 of 0.30 to 1.55 and a ratio of Y2O3/La2O3 of 0.15 to 1.00, and having a glass transition temperature (Tg) of 620° C. or below.
An optical glass comprising in mass % on oxide basis:
- SiO2
- more than 5% and 20% or below
- B2O3
- 5–less than 25%
- Y2O3
- more than 5% and 35% or below
- La2O3
- 10–50%
- ZnO
- more than 5% and less than 25% and
- Li2O
- more than 1% and 6% or below
- and
- Gd2O3
- 0–20% and/or
- Yb2O3
- 0–20% and/or
- ZrO2
- 0–10% and/or
- Ta2O5
- 0–less than 8% and/or
- WO3
- 0–less than 5.5% and/or
- Sb2O3
- 0–1%.
Dependencies are inferred from the claim text.