Source: http://www.eso.org/public/videos/archive/category/esocast
ESOcast Episode 13: A sharper view of the Universe with the VLT Interferometer
1.
[Visuals start]
[Narrator]
Imagine looking up at the night sky and seeing details on the surface of a star millions of millions of kilometres away. Imagine having eyesight so keen that you could check out the surroundings of a black hole. Using ESOs Very Large Telescope Interferometer at Paranal, astronomers are now making these fantasies a reality.
2.
ESOcast intro
This is the ESOcast! Cutting-edge science and life behind the scenes of ESO, the European Southern Observatory. Exploring the ultimate frontier with our host Dr J, a.k.a. Dr Joe Liske.
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[Dr J]
Hello and welcome to another episode of the ESOcast. This time we will look into how a technique called interferometry works at ESOs Very Large Telescope, or VLT for short. Essentially interferometry lets you combine the light collected from the cosmos by two or more telescopes, in turn creating a virtual telescope far bigger than the one that you started with.
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[Narrator]
Each of the four VLT Unit Telescopes has a primary mirror with a diameter of 8.2 metres. Such big mirrors are necessary because they collect more light and provide sharper images. Under ideal conditions and with the appropriate technology, the individual VLT Unit Telescope can see details of objects in space that are equivalent to viewing from here a tennis ball on the International Space Station, which is about 350 km above the ground.
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[Dr J]
This may sound like a really impressive number, but astronomers don't stop there. As frontline research requires studying the heavens in ever-increasing detail, new ways have had to be found to sharpen the VLT's already eagle-eyed vision even further.
6.
[Narrator]
And this is where interferometry comes in. Interferometry combines the light received by two or more telescopes that are simultaneously observing the same object. This allows astronomers to pick out details as sharply as if observing with a single telescope whose mirror has a diameter equivalent to the largest distance between the telescopes.
7.
[Narrator]
The VLT design always had the use of interferometry very much in mind. The four 8.2-metre Unit Telescopes of the VLT were built in a roughly trapezoidal configuration that can generate a virtual telescope mirror of up to 140 metres across. In addition, four, movable, 1.8-metre Auxiliary Telescopes can be combined in a configuration with an equivalent diameter of up to 200 metres. This gives images up to 25 times sharper than those from a single VLT Unit Telescope.
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[Dr J]
Combining the light of different telescopes is a major technical challenge that requires almost unbelievable precision. The light beams from each telescope have to pass underground through a complex system of mirrors and delay lines before they are combined at the common focus.
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[Narrator]
Delay lines are an integral part of the VLT Interferometers complicated optical system. They ensure that the light beams arrive simultaneously
at the common focus. To achieve this, several movable carriages loaded with ultra-smooth mirrors constantly adjust the light beams with extreme precision. The light paths must be kept equal to distances less than 1/1000 of a millimetre over a distance of one hundred metres. Without this kind of accuracy the light cannot be analysed properly by the observatorys instruments.
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[Dr J]
The VLT Interferometer is a true masterpiece of technology. In order to be fully functional every night, its many individual high-tech components must interact flawlessly. Only then can astronomers benefit from the great observational power of this stunning instrument.
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[Narrator]
The VLT interferometer provides astronomers with the ability to study celestial objects in unprecedented detail. It is possible to study the surfaces of distant stars, to determine the shape of asteroids or even capture the surroundings of black holes. The VLT interferometer has produced one of the sharpest images ever obtained of a star. The breathtaking sharpness of this image is the equivalent to seeing the head of a screw on the International Space Station from the ground.
12.
[Dr J]
These are truly fantastic examples of the superb sharpness of the VLT interferometer. In the future, this instrument will surely remain a valuable tool for astronomers to study our Universe in even greater detail.
This is Dr J signing off for the ESOcast. Join me again next time for another cosmic adventure.
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US Aircraft Carrier Fleet Evolution - The Greatest Navy "City of Steel" Fleetby jafalks1,162,781 views
Now, if they can just blank out the secondary mirrors using these cloaking technologies . . . to get rid of the diffractions spikes at every point of a given picture!
oker59 2 weeks ago
I thought ESO had linked the four telescopes interferometricaly a long time ago; as it turns out, ESO just accomplished it(announced it a week or so ago).
I guess the excitement can start now!
oker59 2 weeks ago