Optical glass, optical element, and preform
AssigneeKabushiki Kaisha Ohara
InventorsHiroto Nojima, Fumihiro Oguri
Life of this patent
Estimating the term…
Abstract
To provide an optical glass having the optical characteristics of a high refractive index and low dispersion, and moreover, which makes it possible to further reduce devitrification and which can be stably obtained, and a preform and an optical element using the same. The optical glass comprises, expressed in cation % (mol %), 17.0% to 42.0% of P5+, 7.0% to 30.0% of Al3+, more than 0% to 22.0% of Mg2+, more than 0% to 25.0% Ca2+, more than 0% to 30.0% of Sr2+, more than 0% to 35.0% Ba2+, and expressed in anion % (mol %), a content ratio of F− of 37.0 to 64.0%, a content ratio of O2− of 36.0 to 63.0%, a refractive index (nd) of 1.48 to 1.58, and having an Abbe number (vd) of 70 to 88, and a liquidus temperature of 800° C. or less.
Claims8
An optical glass comprising, expressed in cation % (mol %),
- 17.0% to 42.0% of P5+,
- more than 10.0% to less than 23.0% of Al3+,
- more than 0% to 22.0% of Mg2+,
- more than 0% to 25.0% Ca2+,
- more than 0% to 30.0% Sr2+,
- more than 0% to 35.0% Ba2+,
- comprising, expressed in anion % (mol %),
- 37.0% to 64.0% of F−,
- 36.0% to 63.0% of O2−,
- a total content (Rn+:cation %) of one or more selected from the group consisting of Li+, Na+ and K+ of less than 5.0%,
- a ratio (R2+/Al3+) of the total content ratio (R2+:cation %) of the group consisting of Mg2+, Ca2+, Sr2+ and Ba2+, with respect to the Al3+ content ratio (cation %) of 2.40 to 6.00,
- a ratio (Ba2+/Mg2+) of Ba2+ content (cation %) to Mg2+ content (cation %) of 3.00 or less,
- a ratio (F−/P5+) of F− content (anion %) to P5+ content (cation %) of less than 2.20,
- a refractive index (nd) of 1.50 to 1.54,
- an Abbe number (vd) of 70 to 88, and
- a liquidus temperature of 800° C. or less.
Dependencies are inferred from the claim text.