Heat treatment method of synthetic quartz glass

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United States of America Patent

PATENT NO 9487426
APP PUB NO 20150239766A1
SERIAL NO

14621732

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Abstract

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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.

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Patent Owner(s)

Patent OwnerAddress
SHIN-ETSU CHEMICAL CO LTD4-1 MARUNOUCHI 1-CHOME CHIYODA-KU TOKYO 1000005 ?1000005

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Inventor(s)

Inventor Name Address # of filed Patents Total Citations
Harada, Daijitsu Joetsu, JP 46 74
Takeuchi, Masaki Joetsu, JP 174 1242
Yagi, Hisashi Joetsu, JP 9 35

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