Ohara, Inc.

Atsushi Nagaoka

Ken Kikkawa

Jie Fu

Michiko Ogino

An optical glass having a small partial dispersion ratio (&#x3b8;g,F), while having a refractive index (n) and Abbe number (&#x3bd;) within desired ranges, is obtained. The optical glass, in mass %, comprises 10.0 to 70.0% of an SiOcomponent, 1.0 to 50.0% of an NbOcomponent, and 1.0 to 30.0% of an NaO component, and has a refractive index (n) of 1.62 to 1.75, an Abbe number (&#x3bd;) of 30 to 42, and a partial dispersion ratio (&#x3b8;g,F) of no greater than 0.594.

Optical glass, preform, and optical element

An optical glass having a small partial dispersion ratio (&#x3b8;g,F), while having a refractive index (n) and Abbe number (&#x3bd;) within desired ranges, is obtained. The optical glass, in mol %, comprises 20.0 to 65.0% of an SiOcomponent, 1.0 to 25.0% of an NbOcomponent, and 1.0 to 35.0% of an NaO component, and has a refractive index (n) of 1.62 to 1.75, an Abbe number (&#x3bd;) of 30 to 42, and a partial dispersion ratio (&#x3b8;g,F) of no greater than 0.594.

An optical glass is provided that includes a refractive index (n) of no less than 1.75 and an Abbe number (v) of no less than 10 as optical constants. A BiOcontent is no less than 10% by weight to no more than 80% by weight. The content of SiOis lower than the content of BO. The total content of SiO+BOis from no less than 1% by weight to no more than 60% by weight. The content of RO is from no less than 0.1% by weight to no more than 50% by weight. R represents one or more elements selected from the group consisting of Zn, Ba, Sr, Ca, and Mg. The optical glass has at least one of the properties of being substantially free from opacification and/or being substantially devitrified within the glass body under the conditions of a reheating testing.

Optical glass

The present invention provides optical glasses containing BiOin which the optical glasses have at least one of the properties of being substantially free from opacification and being substantially devitrified within the glass body during reheating steps in production processes, superior chemical durability, and free from black coloring. The optical glass has a refractive index (n) of no less than 1.75 and an Abbe number (&#x3bd;) of no less than 10 as optical constants. The optical glass contains BiOin a content from no less than 10% by weight to less than 90% by weight, and has at least one of the properties of being substantially free from opacification and being substantially devitrified within the glass body under the conditions of a reheating test (a).

Optical glass containing bismuth oxide having good defoamability. The Optical glass contains, as % by mass, from 10 to less than 90% of a Bi2O3 component and at least 0.1% of a TeO2 and/or SeO2 component. The optical glass is on Grade 4 to Grade 1 in 'JOGIS12-1994, Method for Measuring Bubbles in Optical Glass'. By controlling the amount of RO component (R is at least one selected from a group consisting of Zn, Ba, Sr, Ca, Mg) and Rn2O component (Rn&#x2550;Li, Na, K, Cs), the clarifying time may be shortened.

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Sagamihara, Japan

Atsushi Nagaoka