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:
Nov. 08, 2016
Filed:
Feb. 13, 2015
Applicant:
Shin-etsu Chemical Co., Ltd., Tokyo, JP;
Inventors:
Assignee:
SHIN-ETSU CHEMICAL CO., LTD., Tokyo, JP;
Primary Examiner:
Int. Cl.
CPC ...
C03B 25/02 (2006.01); C03B 19/14 (2006.01); C03B 32/00 (2006.01);
U.S. Cl.
CPC ...
C03B 25/02 (2013.01); C03B 19/1453 (2013.01); C03B 32/00 (2013.01); C03B 2201/23 (2013.01);
Abstract
A method for heat treating a synthetic quartz glass having a hydroxyl concentration with a maximum/minimum difference (ΔOH) of less than 350 ppm involves the steps of first heat treatment of holding at 1,150-1,060° C. for a time of 0.5-10 hours, cooling down to a second heat treatment temperature at a rate of −7° C./hr to −30° C./hr, second heat treatment of holding at 1,030-950° C. for a time of 5-20 hours, and annealing at a rate of −25° C./hr to −85° C./hr. Two stages of heat treatment ensures that the glass has a low birefringence.