On Mon, 18 Oct 2004 13:45:21 -0700, Andrew Calvert <[log in to unmask]>
wrote:
>We are in the process of replacing our argon ion lasers with a CO2
>system, and need a laser chamber. I am looking to buy a viewport, but
>may later try the Bernard Marty epoxy technique.
>
>I expect we will need a doubly pumped chamber, with a zinc selenide
>window. Our present laser pans are designed for 1.5" windows. I
>recall from this list a couple of years ago that the ISI windows got
>very expensive and was wondering if anyone has tried the new Ceramaseal
>viewports. They make small 1.1" windows on 2 3/4" conflat flanges for
>$1440 and would do a custom larger 1.6" window on a 4 1/2" flange for
>~$2500. Does anyone have any insight? Ceramaseal also said the custom
>window price would drop if they could make more windows in a batch. If
>other labs are in the market, let me know.
>
>Thanks, Andy
>============
>Andy Calvert ([log in to unmask])
>Volcano Hazards Team
>U.S. Geological Survey
>345 Middlefield Road, MS-937
>Menlo Park, CA 94025
>(650) 329-5276, fax -4664
Dear Andy,
I know some people bought Ceramaseal 2 3/4" ZnSe conflat flanges view port
(about $1400, not differentially pumped view port),and the 40Ar blank is
terrible, 1 Volt per minute for MM5400. Perhaps the sealing material they
use is graphite for no leak could be detected and when they ultrasonic
clean it in acetone some black material was washed out.
To save money, we bought a cleartran (conflat flanges, not differentially
pumped view port) view port from ISI and seal it with E505 again. Before
sealing, the blank is 3mv for 4 minutes. After sealing the blank is
decreased to 1.5mv for 4 minutes and keep on dropping. Unfortunately, we
bake it with heating tape (below 200 degrees) and the solder was melted.
Then we bought ZnS window and glue it on a flange directly, but the stress
transferred directly from the metal to ZnS and broken it during baking (120
degrees in baking case). Then we welded an U-ring on the flange and glue
the ZnS window to the U-ring. Now we can bake it to 120 degrees safely and
the blank for 40Ar is 0.5mv for 4 minutes. It’s still 6 times higher than
our UV chamber and account for 87% blank contribution. The welding and the
baking temperature may be the reason.
Good luck!
Huaiyu
Dr.Huaiyu He
http://www.paleomag.net/members/huaiyuhe/index.html
Institute of Geologhy and Geophysics,
Chinese Academy of Sciences,
Beijing, China
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