Top interview: Dr Patrick McCarthy – boss of the world's future largest optical telescope Construction has now started on the Giant Magellan Telescope – which will be the world's largest optical viewing device mankind has ever built – using record-breaking mirrors and advanced electronics. Youtube Video The telescope, located high in the Chilean mountains, will be able to show us images with up to ten times the …
Far away from the dross of IP lawsuits, Election Bullshit, Social Meedja, and the Nontrepreneuriat.
Let's get some real work done!
Hopefully no-one will find a spotted owl or an ancient burial ground that is tangentially related to a far ancestor to spoil the fun via PC-conscious politicos.
Since the mountain top has already been blasted into pieces and construction has begun it is too late to consider [wild life|ancient burial grounds|religious sites]. The project is on "go" no matter what. The Chilean government was in the past and still is very accommodating in that regard.
That's the advantage of Chile over Hawaii.
You get less US government funding if you don't build in a senators back yard but you also get less opposition from groups using you as a political football.
Caltech (Carnegie's old enemy) chose Hawaii and are having big problems getting their telescope built.
The article goes from Adaptive Optics to CCD Sensors. Hmmm...
Conceptually, perhaps the adaptive optics should be integrated into the optical sensor.
Obviously there is technical challenge of integrating MEMS and optical sensors.
But equally obviously the performance, cost and logistical advantages are vast.
It's so obvious. Somebody must be working on this by now.
How would you do that? the AO should present a focused image to the CCD. How would a CCD correct an unfocused image?
In addition the large CCD camera will be just one of a number of instruments that will be attached to the telescope — 4 currently being built plus a fibre-optic feed, more will be developed. The adaptive optics technology on the mirrors means having to do the job just once and hopefully do it well.
The alternative would be to have correction systems on each instrument, some of which might not be suitable to such manipulation.
In principle, if you had a sufficiently dense detector capable of recording not just the magnitude, but also the phase of the light wave, you can then compute the optical image your telescope would have got if it were perfectly focussed. You would still need to correct for atmospheric distortions, of course. An additional plus is that you won't actually need a mirror as such: you can process your data to form an image corresponding to the wavefront coming from any direction - and potentially observe all of them at once.
The downside is that even if can build a large enough sensor (say, soccer-field-sized) to beat a modern optical telescope, the amount of computing power you would need to synthesize your images at optical wavelengths is so enormous that this whole thing is currently firmly in the science fiction domain. At longer wavelengths used in radioastronomy both the sensor design and the amount of processing needed becomes practical. See: https://www.skatelescope.org/
Cal asked "How would a CCD correct an unfocused image?"
Sorry, I thought that part was the trivial implementation phase. :-)
Ideas are a dime-a-dozen...
The Adaptive Optics is integrated into the sensor box.
Perhaps...
The light might bounce off an array of micro-mirrors (an existing technology: TI's DLP). The exact mechanism would probably need redesign to accomplish this very different function, more up and down, less flipping. Obviously feasible as proven by DLP.
The light might pass through, or bounce off of, a piezoelectric crystal which is laced with a grid of electrodes. Voltages applied would cause a deformation map over the crystal.
The sensor pixels might be installed on MEMS mechanisms to move them up and down. Seems overly tricky.
There might be a small 'wafer thin' flexible mirror that would be deformed by static charge using an array of electrodes. Same basic idea as they use now, but miniaturized.
Remember the Hubble corrective optics? The corrective lenses were the size of coins, for Hubble's 2.4m flawed mirror. Miniaturization and corrective optics work well together.
I can go on all day...
The main point was that 1) yes it's non-trivial, but 2) the performance advantages, cost savings, and logistical advantages are obviously vast.
There's a lot of money spent on Adaptive Optics, so the possible savings might pay for this. Big telescope organizations should take this on, joint venture.
You can for some applications.
There are CCD that can read at video frame rates with no noise, so you read the flickering shimmering image, chose the rare frames where everything was perfect and discard the rest - it's known as "lucky astronomy" but it doesn't work for very wide fields where one part of the image might be good while another area is bad, and you can't use it to feed other instruments like spectrographs.
A big difference between astronomy and camera image stabilisation is that with big mirrors there are dozens of separate patches in the image with different atmosphere and different image movements, with a camera you are cancelling out only movements of the entire camera.
"sensible adjectives"
From Radio...
high frequency (HF)
very high frequency (VHF)
ultra high frequency (UHF)
super high frequency (SHF)
extremely high frequency (EHF)
tremendously high frequency (THF) - not yet widely accepted, but inevitable.
So we're almost out of adjectives. In both fields.
>I like the part where they run out of sensible adjectives to describe the size of the next telescope.
It's a rare example of German irony.
The ESO (european but basically German) telescopes were named NTT (new technology) VLT (very large) and ELT (extremely large) the next one was proposed as OWL (overwhelmingly large)
While the British and American ones were named after famous scientists or donors.
I don't know whether Faux Science Slayer thinks he's slaying Faux Science or whether he's just pretending to slay science, but the article behind that is worth two minutes of your time, if you want a good laugh.
http://canadafreepress.com/article/mysterious-dr-x-says-universe-is-not-expanding
It looks to be the usual Tea Party-type lunacy and denialist dross, but maybe -- just maybe -- it's a skilful satire of the same. It's all there: the basic misunderstanding and mischaracterisations, the inability to spell a famous name consistently, the paranoia about evil scientists manipulating bureaucrats for funding. About the only thing it doesn't mention is that cigarette smoking heals vaccine-damaged babies...
If you add in the fact that the Big Bang was first proposed by a Belgian Catholic priest you can probably bring in the Da Vinci code, the Vatican and the secret order of Belgian Illuminati (slightly less famous than their Bavarian cousins but with better beer)
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