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:
Sep. 26, 2006
Filed:
Dec. 16, 2002
Takayuki Oshima, Koriyama, JP;
Akira Fujinoki, Koriyama, JP;
Takayuki Oshima, Koriyama, JP;
Akira Fujinoki, Koriyama, JP;
Heraeus Quarzglas GmbH & Co. Kg, Hanau, DE;
Shin-Etsu Quartz Products Co., Ltd., Tokyo, JP;
Abstract
An object is to provide a method for producing an optical synthetic quartz glass and an optical synthetic glass, having a birefringence of lower than 0.5 nm/cm and having favorable refractive index distribution, yet without lowering the productivity, as well as to provide an annealing furnace suitably used in practicing said method. In a step of raising the temperature of a columnar optical synthetic quartz glass preform to a temperature of from 800° C. to 1200° C., and after keeping for a definite time, lowering the temperature, the temperature is lowered with a temperature difference of from 1 to 20° C. between the temperature of the light transmitting surface of the optical synthetic quartz glass preform and the temperature of the outer peripheral side surface of the optical synthetic quartz glass preform at temperature-lowering rates of from 2 to 50° C./hour, respectively.