Ohara, Inc.

Kabushiki Kaisha Ohara

Michiko Ogino

Masahiro Onozawa

Jie Fu

Yoshio Mori

Atsushi Nagaoka

Junko Suzuki

Junko Ishioka

Provided is optical glass that does not contain lead, which is an environmental pollutant. The optical glass is ideal for the transmission of light even after being exposed to X-rays, and has a high refractive index. The optical glass comprises, by mass % in terms of oxide versus the glass total mass, 1.0% to 60.0% of an SiOcomponent, and one or more selected from the group consisting of an LaOcomponent, ZrOcomponent, TiOcomponent, NbOcomponent, and TaOas essential components. The optical glass has a refractive index (n) of 1.50 or greater, and has a light intensity recovery rate of 45% or greater when the glass having been irradiated with X-rays with a dose of 2.5 Gy is irradiated with light of a xenon lamp for 11 hours.

Optical glass and core material for optical fiber

There is provided an optical glass with a high refractive index and a low dispersion having a refractive index (nd) of not less than 1.75 and an Abbe's number (&#x3bd;d) of not less than 35 where the image formation characteristic is hardly affected by changes in temperature of the using environment. SiO, BOand LaOare contained as essential components and the ratio of the constituting components are adjusted whereby an optical glass in which a product of &#x3b1; and &#x3b2; where &#x3b1; is an average linear expansion coefficient at &#x2212;30 to +70&#xb0; C. and &#x3b2; is an optical elasticity constant at the wavelength of 546.1 nm is not more than 130&#xd7;10&#xb0; C.&#xd7;nm&#xd7;cm&#xd7;Pais able to be achieved.

Optical glass

An optical glass has a refractive index (nd) of 1.60 or over and excellent transmittance and internal quality. The optical glass comprises 0.1-4 mass % of TaOto total mass of glass calculated on oxide basis, has ratio of 0.95&#x3c;TaO/(TaO+(ZrO)+TiO+NbO+WO)&#xd7;5)&#x2266;1.00, and further comprises SiO+BO+AlO+BaO in a total amount of 81% or over.

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.

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).

Provided is an optical glass having high refractivity and high dispersibility, having good moldability in precision pressing, and having high transmittance and good internal quality, of which the transmittance reduction with time is prevented. The optical glass has a Pt content of at most 1.5 ppm, and is characterized in that, when a sample of the glass polished on both surfaces and having a thickness of 10 mm is irradiated with UV and/or visible light at a light-receiving energy of at most 0.4 mW&#xb7;cmfor at least 200 hours, then the difference in the internal transmittance to light having a wavelength of 420 nm, before and after the irradiation (before irradiation&#x2014;after irradiation) of the sample, as calculated in terms of the sample having a thickness of 10 mm, is at most 0.1.

An optical glass comprises, in mass percent, 15&#x2013;35% of PO, 40&#x2013;60% of NbO, 0.5% to less than 15% of NaO and 3% to less than 25% of BaO, has a ratio in mass % of (BaO+NbO)/{(TiO+WO)&#xd7;3+BiO+NbO}&#x3e;1.0; is free of Pb and As; and has a refractive index (nd) within a range from 1.78 to 1.90 and an Abbe number (&#x3bd;d) within a range from 18 to 27.

An optical glass includes SiO ; PbO; B O ; not less than 0.1 mass % of TeO ; and not less than 0.4 mass % of Li O.

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Sagamihara, Japan

Michiko Ogino