Sumita Optical Glass, Inc.

Koichi Tsuchiya

Shinobu Nagahama

Naruhito Sawanobori

Yoshinori Yamamoto

Masaaki Otsuka

Hideaki Takaku

Koji Nakahata

Toshinori Yuki

An optical glass is provided which does not contain components negatively affecting the environment as environmental loads, and is less colored while having a refractive index maintained moderately high. The optical glass has a composition including, in % by mass, 30% or more and 47% or less of SiO, 0% or more and 10% or less of BO, 3% or more and 12% or less of NaO, 0% or more and 5% or less of LiO, 0% or more and 3.8% or less of CaO, 28% or more and 43% or less of BaO, 3% or more and 16% or less of ZnO, 0% or more and 8% or less of ZrO, 0% or more and 15% or less of LaO, where SbOis excluded from the composition, wherein the optical glass does not contain any of PbO, AsO, and KO.

Optical glass and optical element

The present invention provides a high refractive index, high dispersion optical glass for precision molding, being free from harmful materials causing environmental problems, such as lead oxide, etc., and having a low yield temperature (At), i.e. at most 580&#xb0; C., a refractive index (nd) of at least 1.89 and an Abbe number (&#x3bd;d) of at most 23.0 and further providing a low softening property as well as an improved mass production property with less coloration, which is represented in terms of for making up the glass, by the following chemical composition (wt %): 

Optical glass for precision molding

The present invention provides an optical glass for press molding, in particular, a low softening point glass which contains, in an oxide glass of phosphate type, a durability improving component in addition to glass forming components, and has a weight loss of at most 0.15 weight % in a durability test, and which is represented, in term of elements for making up the glass, by the following chemical composition (mol %):

Optical glass for molding

The present invention provides an optical glass for precision molding, having excellent properties, i.e. yield temperature (At) of at most 550&deg; C., refractive index (nd) of at least 1.83 and Abbe number (&ngr;d) of at most 26.0 and further providing a low softening property as well as an improved mass production property with less coloration, which is represented, in term of atoms for making up the glass, by the following chemical composition (wt %)

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Saitama-ken, Japan

Koichi Tsuchiya