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'Darkness Ray' Beams Invisibility From a Distance
KentuckyFC writes "Optical engineers generally build imaging systems with the best possible resolving power. The basic idea is that an imaging system focuses light into a pattern known as a point spreading function. This consists of a central region of high intensity surrounded by a concentric lobe of lower intensity light. The trick to improving resolution is narrowing and intensifying this central region while suppressing the outer lobe. Now optical engineers have turned this approach on its head by suppressing the central region so that the field intensity here is zero while intensifying the lobe. The result is a three-dimensional beam of darkness that hides any object inside it. The engineers say this region can be huge — up to 8 orders of magnitude bigger than the wavelength of the imaging light. What's more, the optics required to create it are simple and cheap: a lens consisting of concentric dielectric grooves. The team has even tested a prototype capable of hiding a 40-micrometre object in visible laser light."
Can I haz?
I'm starting to think I should subscribe to the medium.com rss feed and skip looking at slashdot
capable of hiding a 40-micrometre object in visible laser light :-)
I would guess that practical applications of this are a few years out
http://en.wikipedia.org/wiki/Troy_Hurtubise
Angel LIght
I love this guy.
Which is ok for point source but not for large objects.
YAMT : Yet Another Misleading Title...
No practical applications here. The girls in the shower room will see the the big black sphere.
Pictures or it didn't happen.
No matter where you go, there you are.
Roll the dice to see if I'm getting drunk...
Ascalante: Your bride is over 3,000 years old.
Kull: She told me she was 19!
Bright Lights Make it Harder to See Dark Stuff Behind Them!
Film at 11!
An enigma, wrapped in a riddle, shrouded in bacon and cheese
I think they must have skipped the chapter in their basic handbook of optics called Babinet's principle. Because they just re-invented Babinet focusing.
Some drink at the fountain of knowledge. Others just gargle.
The technique here is a marginal improvement for practical purposes. There is a light in the room, still you can't see the object, objects that could be as much as 8 wavelengths of that monochromatic light, placed at the correct location. If there is any other source of light, the objects would be plainly visible due to scattering of that light. So it would be impractical to make an invisibility cloak out of it. You need to make the object disappear from all sources of light from all directions.
Though the technique is not going to lead to invisibility cloak, it is probably a great achievement to hide an object when there is one light source. Though people would think is 1 is pretty close to zero, in reality, there is a huge difference between 1 light source and no light source. It is a good great achievement, collect your brownie points scientists.
For others, please move on there is nothing to see here.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
As the beam of darkness brushes across the switch for that would turn it off, then expands to envelop us all in not-light and not-dark. Other things, rogue side-effects of tortured physics nonetheless mediated by gravity, the force nature uses to keep its mistakes firewalled from each other. Cubits and qubits swirl in maelstrom like the brief screaming hiss of a black hole drifting past you on a foul orbit around the center of the Earth leaving sublimely beautiful ellipses of not-matter as its event horizon expands by degree infinitesimal, unobserved but never unnoticed but by those for whom valuable body parts have been thus punctuated, the steady rhythm of science gone mad merging with the jeering laughter of the unquiet dead.
Until we all drown in the bile in the gullet of Schrodinger's cat.
Then nature hands up a sign near the incomprehensibly entangled remnant of our solar system which says.
THIS RIDE IS CLOSED
SORRY FOR THE INCONVENIENCE
<blink>down the rabbit hole</blink>
"Huge" is not a word I've ever associated with "a 40-micrometre object"!
It won't even hide my lair's main gun.
I don't think 8 orders of magnitude would be huge enough to completely obliterate her.
Come to think of it, what's the use if I can still hear her?
By reversing the polarity of the particle flow through the deflector dish, I can ___________________________.
Pretend there is some witty statement here.
Yeah, except when the object IS the source...
And because all objects are sources... (except when at a temperature of 0 Kelvin and black holes)
That's a "bottle beam" (e.g. http://www.ieo.nctu.edu.tw/wfhsieh/pdf_files/2004-10.pdf), not exactly news ...
with powers of invisibility will have to be very small
Here's some recent articles on the topic of shaping light beams so it curves or has extended focal range or dark spots
by the way the "lightning" redirection problem we originally of interest not as a weapon but to create virtual lightning rod arrays in the air to discharge destructive lightning harmlessly. Why? well back then there had been a few great arpanet outages and people realized how vulnerable we were ebcoming to lightning stikes as we depending on the ubiquitous internet to always be able to route around problems. turned out this was a weak point. I suspect it may have become less of one now in part because optical fiber now carries stuff. But I don't know. But it was the utility companies paying for the research at the time.
lightning weapon using self filamentation:
http://www.army.mil/article/82262/Picatinny_engineers_set_phasers_to__fry_/
curving light "beams"
http://www.newscientist.com/article/dn16936-curved-laser-beams-could-help-tame-thunderclouds.html
forming a pseudo non-diffrating "beam" --- which is a totally wrong way to describe this.
http://www.mtu.de/en/technologies/engineering_news/others/Menges_Forming_non-diffracting_beams_en.pdf
that too was applied to the lighning problem
even a slashdot articlee referencing that:
http://science.slashdot.org/story/09/04/15/0147234/curved-laser-beams-could-help-tame-lightning
a patent:
http://www.google.nl/patents/US6937791
Some drink at the fountain of knowledge. Others just gargle.
...objects that could be as much as 8 wavelengths of that monochromatic light
not 8 wavelengths, but "8 orders of magnitude bigger than the wavelength of light used in the imaging process" (from the linked article)
What this paper describes is basically using a phase-shift mask to produce a dark spot. There are established techniques for doing this in microlithography, known as "chromeless phase-shift lithography" (CPL). In lithography, one is generally trying to produce patterns of relative light and dark regions that are very small, so there's an emphasis on making thin lines, tiny contact spots, and sharp corners. But a CPL mask can produce fairly arbitrary patterns. For example, a dense checkerboard of zero and pi phase shift regions can produce a large region of region of relative darkness that could be much larger than the single point described in the paper. In practice, a large region can also be produced using conventional "chromed" lithography - a dark spot in the mask produces a dark shadow in the region behind it - but people wouldn't be so impressed by using a mask with a dark spot in it to produce a "three-dimensional beam of darkness."
I think this has more of an impact on communications than it does on "invisibility cloaks"
Won't work as a spot light, the backscatter off the walls and floor will still illuminate the object in the dark spot in the beam.
So what kind of application could it have? You pretty much do the same thing by putting your object out of the way of the beam of light.
Sounds more like a kind of particle trap with lasers
The above says
8 orders of magnitude bigger than the wave length
However the abstract of the article itself says instead
8 orders of magnitude bigger than the square of the wave length.
A significant difference.
Is this basically a more refined version of what happens when you focus a maglight beam so that the light intensity is on the outer edge with a dark middle?
Light bulbs are not actually "light bulbs" but dark absorbers. When you turn them on, they suck the dark out of the room. You can prove this by holding your hand under a "light bulb". The dark will stack up under your hand where its path to the absorber is blocked by your hand. When they quit working and turn a dark color, it's not because they burnt out, it's because they're full.
For very, very small values of "huge".
Mother of God, this "beta" is awful.
Hmm, up to 40 microns. I can think of some simpler ways to hide a microscopic (or near microscopic) object. Such as, for example - do nothing. Most of the dust in the room is bigger than 40 microns, so no-one is going to see it.
Who wants to bet this project was taxpayer funded by a government grant?
Your lantern has gone out.
I expect this is of proper scientific merit and interest to those who understand these things, but I'm not one of them. All I get from the summary (and what little I can glean from the article this late at night) seems to amount to hiding something by not lighting it up in the first place. And I can think of easier ways to do that...
If something's already lit by another light source, surely you couldn't really actually use this like a "beam of darkness" as is suggested?
systemd is Roko's Basilisk.
Thanks for the correction. 8 orders of mag above wave length? That would be stunning achievement.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
You're forgetting one thing. All a repressive government has to do is control all the street lights and interconnect them. They could choose which citizens are allowed to see where they are going.
Which means 460nm light would hide a 46-meter object.
That sounds fairly outlandish, I would think 8 times (3680nm) would be more appropriate and viable.
Still waiting on Serviscope_minor to wake up to fucking reality and realize that Jessica Price isn't going to fuck him.
That was awesome. Thank you. I love hearing odd view points like that.
The team has even tested a prototype capable of hiding a 40-micrometre object in visible laser light.
Hell, I can't see something 40 microns wide on a good day! No "darkness beam" needed to hide that from me!
I expect this is of proper scientific merit and interest to those who understand these things, but I'm not one of them. All I get from the summary (and what little I can glean from the article this late at night) seems to amount to hiding something by not lighting it up in the first place. And I can think of easier ways to do that...
If something's already lit by another light source, surely you couldn't really actually use this like a "beam of darkness" as is suggested?
Why not? Ever watch a film on a white projector screen, showing a 'black' object? You know the screen is white. You know you're not projecting 'black light'. You know there's plenty of light splashing around with which to see the screen. You can even turn the projector off, not add any more lights, and see that the whole thing is white. And yet there it is, a black obect on the screen just because the areas around it are so much brighter. Seems like the same principle. Add brighter light to surrounding areas and your eyes/brain will adjust to seeing what's left as hidden in darkness. There's white there, there's enough light to see it, but you don't.
8 orders with respect to the wavelength squared. In other words 4 orders with respect to wavelength. That is a few hunder um.
moving on
Colorblindness is not a disease, it's a way of living
Radar has longer wavelength - so you can hide bigger objects from radar . . .
Well if you actually read the paper that it's 8 orders of magnitude above lambda squared. The summary just omits the "squared". Since lambda is something 10^-6m-ish, 8 orders of magnitude above that would be 100m, but 8 orders of magnitude above its square are just like 100um.