Ohara, Inc.

Hiroto Nojima

Fumihiro Oguri

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 P, 7.0% to 30.0% of Al, more than 0% to 22.0% of Mg, more than 0% to 25.0% Ca, more than 0% to 30.0% of Sr, more than 0% to 35.0% Ba, and expressed in anion % (mol %), a content ratio of Fof 37.0 to 64.0%, a content ratio of Oof 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&#xb0; C. or less.

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Kanagawa, Japan

Hiroto Nojima