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To: LibWhacker

Remember when we (the US) used to do stuff like this (build the best and biggest of everything)?


10 posted on 06/13/2012 11:32:14 PM PDT by aquila48
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To: aquila48

I do, indeed. Zero’s made us second rate in science overnight. Next to follow will be economic and military might.


11 posted on 06/13/2012 11:35:58 PM PDT by LibWhacker
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To: aquila48
We actually did build one, and then two telescopes very much like this. Known now as the Keck telescopes at Muana Kea, they were designed at UC’s Lawrence Berkeley Lab, using the same stressed mirror technology. The Keck design is composed of 36 two meter segments, along with the active support mechanism which we called a “whiffletree” for what reason I don't recall.

Our problem was money, until the principle scientist, Jerry Nelson, whose alma mater was Cal Tech, found money from the Keck family. Polishing a mirror that large is a major problem because there are few vacuum chambers large enough to contain the 2 meter honeycombed structures. Vacuum chambers are necessary because measuring to enable the smoothing of the hills and valleys of the surface within less than a wavelength at the designed wavelength is done with laser interferometers, and normal air currents mean differences in temperature and pressure sufficient to diffract the laser to and from the mirror. Money allowed Jerry to farm the polishing out to a world famous optics house. That is probably why this new device uses 1.4 meter rather than 2 or more meter mirrors.

Bottom line: this instrument will be a wonderful tool, but it is a derivative design. Adaptive mirrors are fascinating, and have been used for more than fifty years in military optics long before the Keck became a reality, though some of the physicists and engineers at LBL had developed some earlier adaptive optic technology for use at the Lick Observatory and on at least one orbiting telescope. We used PDP-11’s for the adaptive focus elements on the “Ten Meter Telescope” - later named Keck. The difference today will be the advantage of faster processors and improved optical sensors. It is very doable, and I hope funding is a reality. These days it is not easy to justify a larger anything that does not generate revenue or promise employment except for a few dozen scientists and as many engineers and technicians.

21 posted on 06/14/2012 1:33:01 AM PDT by Spaulding
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