The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 30, 2004
Filed:
Mar. 19, 2001
Masahiro Onozawa, Sagamihara, JP;
Takehiro Sakamoto, Sagamihara, JP;
Kabushiki Kaisha Ohara, Sagamihara, JP;
Abstract
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° 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;=2.5. The optical glass for precision press molding has a specific composition range of SiO —B O —La O —Y O —Ta O —CaO—Li O system composition.