by: John M. Hill
As of 00:50 this morning we have started cooling our new properly thick
faceplate. The faceplace as seen on the video images is estimated to be
1.5 inches (38 mm) at the previously thin spot at 60 degrees and
more like 1.7 inches near the center.
About a dozen people in the control room had an interesting time
watching the glass "tide" roll slowly across the surface of the mirror
after the glass blocks melted. The timescale for glass motion turned
out to be about the same as an ocean tide. We used every kilowatt of
lid power that we could muster in order to bring the faceplate up
to casting temperature in a reasonable length of time.
Besides the people here in the Mirror Lab, people were watching on the
web from all over the world, including Italy, Germany, Brazil and
Australia. Images will continue to update on the web, but don't expect
them to change much from now on. They may sharpen a bit as the cameras
cool off. We will produce some nifty video time lapse in MPEG format in
a few days. I hope the automatic temperature updates are routine
by the time of the next casting (Fall 1998).
The oven will continue to spin at 6.81 rpm through Wednesday evening,
then we will begin the three-month annealing and cooling cycle.
Here is a last overview page of oven pilot data before cooling started:
Executive Summary:
The remelting of 2.1 additional tons of E6 glass
onto the faceplate of the LBT 8.4 meter seems to have been
a grand success. As Dan Watson puts it, the faceplate is now
"properly thick".
Oven Overview oven0v0 Wed Jun 11 00:47:09 1997
Zone Clock Time Sch Temp Avg Temp Error Rate Scatter Deviation
Z0 R 41:16:38 1180.0 1164.3 15.7 0.0 3.1 100.
Z1 R 41:16:38 1180.0 1165.7 14.3 0.0 4.7 100.
Z2 R 41:16:38 1180.0 1167.4 12.6 0.0 5.5 100.
Z3 R 41:16:38 650.0 701.6 -51.6 0.0 67.9 70.
Z4 R 41:16:38 650.0 664.8 -14.8 0.0 39.6 70.
Z5 R 41:16:38 650.0 664.1 -14.1 0.0 33.8 70.
Z6 R 41:16:38 650.0 920.2 -270.2 0.0 13.2 150.
Z7 R 41:16:38 128.8 134.8 -6.0 0.0 39.2 70.
Z8 R 41:16:38 30.0 41.6 -11.6 0.0 3.7 10.
Z9 R 41:16:38 1180.0 993.0 187.0 0.0 0.0 100.
Z10 R 41:16:38 30.0 41.9 -11.9 0.0 2.1 10.
Z11 R 41:16:39 35.0 34.3 0.7 0.0 12.6 15.
Z12 R 41:16:38 55.0 44.5 10.5 0.0 4.3 30.
Z13 R 41:16:38 40.0 46.3 -6.3 0.0 7.7 20.
Z14 R 41:16:38 40.0 42.9 -2.9 0.0 0.0 10.
Z15 R 41:16:39 30.0 30.2 -0.2 0.0 16.1 10.
R R 41:16:39 6.740 6.727 0.013 0.000 70.00
Zone L Check Power Goal Temp To Goal @ClockTime @RealTime
Z0 o E 220 1180.0 00:00:00 41:16:38 Wed Jun 11 00:47:09 199
Z1 o E 220 1180.0 00:00:00 41:16:38 Wed Jun 11 00:47:09 199
Z2 o E 217 1180.0 00:00:00 41:16:38 Wed Jun 11 00:47:09 199
Z3 o E 0 650.0 00:00:00 41:16:38 Wed Jun 11 00:47:09 199
Z4 o E 2 650.0 00:00:00 41:16:38 Wed Jun 11 00:47:09 199
Z5 o E 0 650.0 00:00:00 41:16:38 Wed Jun 11 00:47:09 199
Z6 o E 0 650.0 00:00:00 41:16:38 Wed Jun 11 00:47:09 199
Z7 o E 26 128.8 00:00:00 41:16:38 Wed Jun 11 00:47:09 199
Z8 o E 0 30.0 00:00:00 41:16:38 Wed Jun 11 00:47:09 199
Z9 o D 0 1180.0 00:00:00 41:16:38 Wed Jun 11 00:47:09 199
Z10 o E 0 30.0 00:00:00 41:16:38 Wed Jun 11 00:47:09 199
Z11 p E 0 35.0 00:00:59 41:17:38 Wed Jun 11 01:46:09 199
Z12 o E 0 55.0 00:00:00 41:16:38 Wed Jun 11 00:47:09 199
Z13 o E 0 40.0 00:00:00 41:16:38 Wed Jun 11 00:47:09 199
Z14 o E 0 40.0 00:00:00 41:16:38 Wed Jun 11 00:47:09 199
Z15 p E 0 30.0 00:00:59 41:17:38 Wed Jun 11 01:46:09 199
R p E 6.740 00:00:59 41:17:38 Wed Jun 11 01:46:09 199
Analog Data
TOT 2704.1A (2789.2A) 100.152HE ( 103.304HE) 732.423KW ( 755.641KW)
Ciao,
John
(sleepy LBT Director)
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