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Looking Directly at Extrasolar Planets
D2Deek writes "Science Daily is reporting on a new device called an Optical Vortex Coronagraph that's been invented to directly image planets orbiting other stars by using a special lens that "spins out" the light from the star leaving only the reflected light from the planet." I just can't imagine trying to clean a lens shaped like a giant corkscrew.
Seeing the planet next to its bright star has been compared to trying to discern, from a hundred meters away, the light of a match held up next to the glare of an automobile's headlight.
I thought a planet must be illuminated by light from a star, and not emitting light itself?
Anyway, this technology might be useful for photography, so that one will never get an overexposed shot again.
Rock that crushes, Paper & Scissors that don't matter.
Do not look directly at extrasolar planets with remaining good eye.
Dark Reflection
Is that anything like the Total Perspective Vortex ??
try { do() || do_not(); } catch (JediException err) { yoda(err); }
A new optical device might allow astronomers to view extrasolar planets directly without the annoying glare of the parent star. It would do this by "nulling" out the light of the parent star by exploiting its wave nature, leaving the reflected light from the nearby planet to be observed in space-based detectors.
About ten years ago, the presence of planets around stars other than our sun was first deduced by the very tiny wobble in the star's spectrum of light imposed by the mutual tug between the star and its satellite. Since then, more than 100 extrasolar planets have been detected in this way. Also, in a few cases the slight diminution in the star's radiation caused by the transit of the planet across in front of the star has been observed. Many astronomers would, however, like to view the planet directly, a difficult thing to do.
Seeing the planet next to its bright star has been compared to trying to discern, from a hundred meters away, the light of a match held up next to the glare of an automobile's headlight. The approach taken by Grover Swartzlander and his colleagues at the University of Arizona is to eliminate the star's light by sending it through a special helical-shaped mask, a sort of lens whose geometry resembles that of a spiral staircase turned on its side.
The process works in the following way: light passing through the thicker and central part of the mask is slowed down. Because of the graduated shape of the glass, an "optical vortex" is created: the light coming along the axis of the mask is, in effect, spun out of the image. It is nulled, as if an opaque mask had been placed across the image of the star, but leaving the light from the nearby planet unaffected.
The idea of an optical vortex has been around for many years, but it has never been applied to astronomy before. In lab trials of the optical vortex mask, light from mock stars has been reduced by factors of 100 to 1000, while light from a nearby "planet" was unaffected (see figure).
Attaching their device to a telescope on Mt. Lemon outside Tucson, Arizona, the researchers took pictures of Saturn and its nearby rings to demonstrate the ease of integrating the mask into telescopic imaging system. This is, according to Swartzlander (520-626-3723, grovers@optics.arizona.edu), a more practical technique than merely attempting to cover the star's image, as is done in coronagraphs, devices for observing our sun's corona by masking out the disk of the sun. It could fully come into its own on a project like the Terrestrial Planet Finder, or TPF, a proposed orbiting telescope to be developed over the coming decade and designed to image exoplanets.
Foo et al., Optics Letters, 15 December 2005 Summary of articles related to optical vortex on Swartzlander's Web page
Someone more patient than I can put in the links to the figures. See http://aip.org/pnu/2005/755.html for everything.
I just can't imagine trying to clean a lens shaped like a giant corkscrew.
Just run a lint-free Debian logo through it a couple of times.
"I'd rather be a lightning rod than a seismometer." -Ken Kesey
The submitter mentioned cleaning lenses and other optical equipment. I want to comment that that's a very tricky thing. Most optical manuals just say: Do not attempt to clean!! Some recent developments are in the area of strip coatings (you pour a polymer over the surface and peel it off to remove dirt without damaging the optics). This has been tried since the early XX century but only recently has became practical. Here's a link to a group that developed a sucessful formula for that process: http://www.uwplatt.edu/~hamiltoj/
I wonder if it could be applied to observing galaxies too... I mean, I'd be curious to know what other uses could be found to this technique
You just got troll'd!
A corkscrew shaped lens, eh? It's amazing the topographical capacity in lens engineering. I bet this is all fused silica. When will we have single crystal sciu light sources? I'm in no hurry. I study the magnetic recombinance of solar coronas. No need here for that source type. Let me jump back to times when I could just play games and not worry about lens and abberration and physics. GRRRR! Real life sucks.
"Destroy science and religion. Science would re-emerge exactly the same; but not religion." - Penn Jillette, paraphrased
It's worth RTFA just to see a reference to "Foo et al."
(The full paper title is "Optical Vortex Coronagraph" by Gregory Foo, David M. Palacios, Grover A. Swartzlander Jr., College of Optical Sciences, University of Arizona).
"How to Do Nothing," kids activities, back in print!
http://www.u.arizona.edu/~grovers/ovc.html
Optical Vortex Coronagraph Figures
Optics Letters Preprint (4.8 Mb)[pdf] --- To Appear 15 December (ol.osa.org)
This work first appeared in the Master Degree Thesis of Greg Foo:
OSC QC350.O77 Vol. 353, 2005.
[Fuck Beta]
o0t!
"As Gilman looked into the Optical Vortex Coronagraph at the extrasolar planet, he became conscious of some formless alien presence watching him with horrible intentness. He felt entangled with something -- something which was not in the telescope, but which had looked through it at him. Something which would ceaselessly follow him.
"Cautious investigators will hesitate to challenge the common belief that Gilman was killed by lightning, or by some profound nervous shock derived from an electrical discharge. Archaeologists and astronomers, however, are still trying to explain the bizarre designs impressed on the special helical-shaped mask, whose inner side bore ominous stains."
You wont be able to see any surface details, but the point, for those who don't already know, is that if you can look at just the light that's reflected, then you can run that light through a spectroscope. If you see in the spectroscope that there is free oxygen in the atmosphere, then you've probably found life. See, free oxygen (O2) doesn't occur anywhere in nature - except where it's created by life. So, if you find lots of O2 in the atmosphere, you've found a living planet (and a reason to build daedelus)
Can't image things until you can find them. Can't find them if the starlight is making it impossible to discern the planet.
m0nstr42.blogspot.com
Frankly, I'm more interested in a comprehensive set of photos of our own solar system's planets, such as Pluto and the various "Planet X" candidates that pop on and off the public debate radar from over the years. At least we have the technology to actually visit these places today were we so inclined.
I'm not saying it's unimportant to continue with research like this, only that I wish more effort were put into slightly less glamorous subjects like Pluto that could actually do us some tangible good one day...
This is extremely cool. I was wondering if there would be any way to do this in software (at least that technical explanation page shows there is a simulator) but thoguht that if it is based on slowing down light of a certain color, you would have to have all the phase info stored. Or at least extremely high resolution/range to have any data left after subtracting the green. I could be way off here but does anyone know of a way this technique could be used on an amateur telescope computationally based on light captured by a ccd without actually physically building a vortex lens? Is it true that this is based on a single color? Also, if you worked on the spectra of the star would this not also include spectra of the planet, i.e. is this really based on a pure black body incandescense i.e. pure green for this star and not really the full spectra of the star? Thanks.
For information, the European Space agency has a project named Darwin that intends to cancel the light of a star by destructive interferometry, leaving the neigboring planet alone: from its specifications, I retain that in order to "see" the planet, you must damp the star from a factor 10^9 in visible light (10^6 in IR). Basically this is how the Earth looks like close to the sun: 10^9 times less brilliant.
Compared to this, the damping factor announced in the original paper (between 100 and 1000), would look, well, definitely unsufficient if it weren't for just a demo today...
I hope I wasn't too naughty, I didn't talk about the angular resolution needed.
Hervé
Herve S.