Kabushiki Kaisha Ohara

Kabushiki Kaisha Ohara Kogaku Garasu Seizosho

Kabushiki Kaisha Ohara Kogaku

Muneo Nakahara

Tatsuya Senoo

Fujio Komorita

Satoru Matsumoto

Akira Masumura

Katsuhiko Yamaguchi

Yoshio Mori

Futoshi Ishizaki

Michiko Morishita

Hiroshi Shishido

An optical glass wherein an amount of change in refractive index (&#x394;n: difference in refractive index between a state before radiation and a state after radiation) caused by radiation of laser beam at wavelength of 351 nm having average output power of 0.43 W, pulse repetition rate of 5 kHz and pulse width of 400 ns for one hour is 5 ppm or below is provided. The optical glass comprises a fluorine ingredient and/or a titanium oxide ingredient and/or an arsenic oxide ingredient. The optical glass suffers little change in refractive index by radiation of strong light having wavelengths of 300 nm to 400 nm such as ultraviolet laser.

Optical glass suffering little change in refractive index by radiation of light

An optical glass wherein an amount of change in refractive index (&#x394;n: difference in refractive index between a state before radiation and a state after radiation) caused by radiation of laser beam at wavelength of 351 nm having average output power of 0.43W, pulse repetition rate of 5 kHz and pulse width of 400 ns for one hour is 5 ppm or below is provided. The optical glass comprises a fluorine ingredient and/or a titanium oxide ingredient and/or an arsenic oxide ingredient. The optical glass suffers little change in refractive index by radiation of strong light having wavelengths of 300 nm to 400 nm such as ultraviolet laser.

An optical glass comprises the following composition in mass percent of: SiO 18-29%; PbO 68-78%; and TeO 0.1-3.5%; wherein the glass has optical constants which are a refractive index (nd) having a range of 1.75 to 1.87 and an Abbe number (&ngr;b) having a range of 21 to 28; and a wavelength of a light transmitted through the glass having a thickness of 10&plusmn;0.1 mm at a transmittance of 80% by including a reflection loss, is not more than 420 nm.

Optical glass

An optical glass having optical constants of refractive index within the range of 1.55-1.75 and Abbe number (.nu. d) within the range of 25-51 and having large negative anomalous dispersion which is substantially free of lead and arsenic compounds includes as its essential ingredients in weigth percent 10-&gt;40% SiO.sub.2, 12.5-35% B.sub.2 O.sub.3, 3-20% ZrO.sub.2 and 6-30% Nb.sub.2 O.sub.5.

Optical glass having a negative anomalous dispersion

An optical glass which is a SiO.sub.2 --TiO.sub.2 --K.sub.2 O--RO (where R represents Mg, Ca, Sr, Ba and Zn metal elements) system glass of a specific content range exhibits optical constants of a refractive index (Nd) of about 1.58-1.78 and Abbe number (.nu.d) of about 28-45, is free of PbO and has an improved property against devitrification.

An optical glass which is a SiO.sub.2 --B.sub.2 O.sub.3 --(TiO.sub.2 +ZrO.sub.2)--SrO--BaO--R'.sub.2 O system of a specific composition range exhibits optical constants of a refractive index (Nd) of 1.57-1.75 and Abbe number (.nu.d) of 30-55, is free of PbO and has improved stability against devitrification and tinting and improved chemical durability.

An optical glass consisting basically of a B.sub.2 O.sub.3 -La.sub.2 O.sub.3 - ZrO.sub.2 -Nb.sub.2 O.sub.5 -PbO-BaO (and/or ZnO) system is free from a poisonous CdO or ThO.sub.2 component and has an excellent light transmission property in a transition region from an ultraviolet portion to a visible portion as compared with conventional optical glasses having the same optical properties.

An optical glass consisting essentially of a B.sub.2 O.sub.3 --La.sub.2 O.sub.3 --Gd.sub.2 O.sub.3 --WO.sub.3 --ZrO.sub.2 and/or Ta.sub.2 O.sub.5 system has high refractive and low dispersive characteristics with optical constants of 1.85-1.96 for Nd and 43-28 for .nu.d, is free of poisonous ThO.sub.2, CdO and BeO ingredients, and suitable for mass production.

An optical glass consisting basically of a B.sub.2 O.sub.3 -- SiO.sub.2 -- La.sub.2 O.sub.3 -- ZrO.sub.2 -- TiO.sub.2 -- ZnO -- BaO system can be produced at a lower melting temperature and in a shorter melting time than it has heretofore been possible by replacing Ta.sub.2 O.sub.5, Nb.sub.2 O.sub.5 and WO.sub.3 used in the conventional optical glasses with ZnO.

Growing community of inventors

Sagamihara, Japan

Muneo Nakahara