Friday, September 6, 2013

A More Normal Post!

Two weeks into Melinda's first round of chemo and she continues to improve.  Her nausea passed a few days ago, and her strength has returned in part - enough to do chores around the house, get the mail, drive herself to the store.  We're happy about that, and hope that in future 3-week cycles, that there will only be about a week of unpleasantness...  The only lingering effects are that food still tastes funny, mostly salty or metallic, but she has learned to use a straw with liquids to get them past the tip of her tongue.  The other effect is that her hair is thinning, but no panic there as it was expected.  She already has scarves on hand and has friends knitting various hats and coverings to temporarily do the job of her tresses.  Doctors will insert a port next week so that they won't have to poke veins to administer chemo and collect blood samples in the near future either, so we are looking forward to that too.  And we're making plans for the weekend, and plan to get out of the house a time or two...

So with that bit of better news, it is time to catch up on other business!  Two weeks tomorrow the Mirror Lab held an open house for the casting of the 3rd mirror for the Giant Magellan Telescope.  For those of you new to the idea, imagine 7 huge mirrors, each about 28 feet (8.4 meters) in diameter, all collecting light to a common focus.  Astronomers are all about collecting and analyzing light, and anyone associated with the project will look at every milestone with delight, so time to celebrate.  The day of the peak temperature, when the glass melted into the mold, there were over 200 partners and affiliates that came through the lab, and it was "all hands on deck" for our staff to guide and educate the VIPs through the facility.  The star of the show was the spinning oven with 20 tons of molten glass inside.  Rotating at about 4 rpm to maintain the desired 36 meter radius of curvature in the molten surface, it was an amazing spectacle.  During the day, the temperature was still climbing - up over 1050C, but still short of the peak at 1160C.  But it was hot enough you could feel the radiant heat emitted, and you could see the red-orange of the oven's fiery interior at a few spots - small gaps in the insulation or empty thermocouple holes that allowed an interior peek.

These camera views are from digital cameras that viewed the interior through little sapphire windows that wouldn't melt with the intense heat. And while the interior was glowing, these pictures were taken in blue light with the interior lit up with flash units.  The three pictures here show different phases of the casting as the temperature rose.  The first at left above shows the glass chunks pretty much unchanged from room temperature as the interior climbed near the softening point of 750C.  The next one at right shows the view about the time of the open house - over 1000C, when the glass formed a solid disk about 6" thick, but still too viscous to run into the mold.  Finally at left, taken near the peak temperature shows the glass now fully filling the mold, and the faceplate thickness at about 2" thick. There were hundreds of pictures taken in all, and the time lapse of the melting is included with my own images in the video below...  I think these pictures/sequences are just about the most amazing things I see coming out of the lab!

We had a number of other activities visible to the guests in the Lab.  Besides the casting operation, over in the Polishing Lab we had 2 machines running - polishing one of the surfaces for the 8.4 meter diameter Large Synoptic Survey Telescope (LSST), and also grinding the backplate of the 6.5 meter San Pedro Martir Telescope (SPM).  As my schedule permitted (I was running a booth explaining the generating, grinding and polishing operations), I set up my own camera on a tripod with a timer taking a picture every 2 seconds.  Later I found I could even take one per second if I changed to a smaller file size. These images from around the lab were imported into Windows Movie Maker and turned into a 3-minute time lapse of the open house activities.  You can see perhaps a little better about the movement of the equipment as it polishes the surface.  Interestingly, the initial sequence of the rotating oven, at a frame every 2 seconds, exhibits a "stroboscopic" effect, where the oven appears to rotate the opposite direction it was actually turning!  Sort of like in the old TV westerns when the wagon wheels appeared to turn backwards, it is an artifact of the frame rate and wagon spokes creating an interesting optical illusion...


After all the VIPs had departed the facility for the rest of the day's activity (meetings and a dinner at an undisclosed location!), the pressure was off for the rest of the Mirror Lab crew.  Here, a couple staffers "vogue" in front of the spinning oven for our staff photographer (not me!) to take their image(also at the end of the time lapse above).  The only ones not relaxing were the casting crew.  They were responsible for the entire melting process and were little seen during the hubbub of the day's activities.  In fact, about the time we were leaving, we heard reports of their concern for an odd appearance of turbulence and bubbles near the edge of the mirror (seen in the glass-melting section of the time-lapse above).  That particular effect had not been seen before, but evidently came out ok in the end as the subsequent casting looks pretty good.  We'll find out for sure when the oven is opened about Thansgiving! 

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