Ohara, Inc.

Ken Kikkawa

Atsushi Nagaoka

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.

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Sagamihara, Japan

Ken Kikkawa