Kabushiki Kaisha Ohara

Ohara, Inc.

Kabushiki Kaisya Ohara

Masahiro Onozawa

Michiko Ogino

Junko Ishioka

Yoshio Mori

Junko Suzuki

Shinya Mashiko

Michiko Morishita

Hiroaki Tomoe

Takehiro Sakamoto

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

Optical glass has a refractive index of 1.83 or above and an Abbe number of 26 or less and contains SiO, TiO, NbOand NaO as its essential constituents in such proportions on a final oxide basis that the amounts of its oxide constituents as expressed on a mass percentage basis may satisfy the relationship:(TiO+NbO)/(NaO+KO)=3.0 to 4.0.

An optical glass having a refractive index (nd) within a range from 141 to 1.47 and an Abbe number (&#x3bd;d) within a range from 90 to 100 comprises in mass % on element basis: and comprises, as an essential component, one or more elements selected from the group consisting of Ca, Sr and Ba. In this optical glass, the ratio (Si+B+P+Al)/F is within a range from 0.15 to 0.40.

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 having optical constants of refractive index (nd) within a range from 1.49 to 1.54 and Abbe number (&#x3bd; d) within a range from 55 to 65 comprises, in mass %, 

An optical glass comprising in mass %: The optical glass should preferably contain 0.1-5% WO, 3.6-15% MgO, 0.1-5% LiO+NaO+KO, 0&#x2014;less than 0.5% and SbO+AsOwith the mass ratio of ZnO/BaO being 0.12&#x2014;less than 0.50. The optical glass should preferably have refractive index (nd) within a range from 1.54 to 1.65 and Abbe number (&#x3bd;d) within a range exceeding 57 up to 69 and liquid phase temperature within a range from 870&#xb0; C. to 930&#xb0; C. There is provided an optical glass having high resistance to devitrification and medium refractive index and low dispersion characteristics which is free of ingredients such as TaOhaving a high cost of raw material and therefore can be manufactured at a relatively low cost of raw materials.

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 having a positive anomalous dispersion comprises, in mass %, is free of PbO and AsOexcept for unavoidable mixing of these compounds as impurities, has optical constants of a refractive index (nd) within the range from 1.48 to less than 1.55 and an Abbe number (&#x3bd;d) within the range from 45 to 55, and has an anomalous dispersion (&#x394;&#x3b8;g,F) of +0.0010 or over.

Optical glass having an anomalous dispersion

An optical glass which is free of PbO which causes environmental pollution and also is free of expensive TaOand NbOcomprises, in mass %, and has optical constants of a refractive index (nd) within a range from 1.55 to less than 1.67 and an Abbe number (&#x3bd;d) within a range from 30 to 45.

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.

An optical glass for precision press molding that has desired optical constants, a low glass transformation point (Tg), and a devitrification temperature that is lower than a temperature of a glass melt, at which a viscosity suitable for forming of a preform material is obtained, is provided. The optical glass for precision press molding has a lanthanum borosilicate system glass having optical constants of refractive index (nd) within a range from 1.65 to 1.73 and Abbe number (&ngr;d) within a range from 50 to 60, a Tg within a range of 480-580&deg; C. The optical glass for precision press molding has a devitrification temperature that is lower than a temperature of the glass melt when the glass melt has a viscosity &eegr; (poise) of log &eegr;&equals;2.5. The optical glass for precision press molding has a specific composition range of SiO &mdash;B O &mdash;La O &mdash;Y O &mdash;Ta O &mdash;CaO&mdash;Li O system composition.

Optical glass for precision press molding and optical element

An optical glass has a large negative anomalous dispersion value and optical constants of refractive index (nd) within a range of 1.65-1.80 and Abbe number (.nu.d) within a range of 28-42. The optical glass includes, as its essential ingredients, in weight percent, 20-50% SiO.sub.2, 6-20% B.sub.2 O.sub.3 where SiO.sub.2 /B.sub.2 O.sub.3 .ltoreq.6, 0.5-15% ZrO.sub.2 and 31-50% Nb.sub.2 O.sub.5.

Optical glass having a negative anomalous dispersion

An optical glass having optical constants of a refractive index (Nd) from 1.50 to 1.60 and an Abbe number (.nu.d) ranging from 62 to 73, a transformation temperature (Tg) of 550.degree. C. or below, and barely cracks or sticks to metal molds when the glass is subjected to mold pressing, maintains excellent chemical durability, and having softening capability at a low temperature which can be obtained by restricting the composition of the glass in weight percents within a specific range of a SiO.sub.2 --Al.sub.2 O.sub.3 --P.sub.2 O.sub.5 --R.sub.2 O system.

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Sagamihara, Japan

Masahiro Onozawa