Laser Turns All Metals Black 333
Roland Piquepaille writes "Researchers at the University of Rochester have found a way to change the properties of almost any metal by using a femtosecond laser pulse. This ultra-intense laser blast creates true 'black metal' from copper, gold or zinc by forming nanostructures at the surface of the metal. As these nanostructures capture radiation, the metals turn black. And as the process needs surprisingly low power, it could soon be used for a variety of applications, such as stealth planes, black jewels or car paintings. But read more for additional references and a picture of this femtosecond laser system."
Applications (Score:2, Informative)
Re:anything special? (Score:4, Informative)
tag as "pigpile" (Score:1, Informative)
Comment removed (Score:3, Informative)
Re:anything special? (Score:5, Informative)
No, because if it was invisible you'd be able to see what was behind it; if it merely absorbs the light that falls on it, you'd see a black shape instead...
Obligatory Pigpile Rant (Score:4, Informative)
* He gets a lot of articles posted to the front page, which makes the rest of us jealous.
* His articles tend toward pseudoscience, or at least towards the sort of flashy, headline-inspiring science that does little to advance human knowledge.
* He used to link to his personal blog, which really irritated people who'd love to have their own blogs get Slashdotted on a regular basis.
* He now links to his zdnet blog, which really irritates people who'd love to have their own blogs get picked up by a big corporate website.
* To top it all off, he's French, so all the right-wing nutters hate him automatically.
My irritation comes mostly from the second point -- and, I'll confess, the first as well. But as his defenders (and even the Slashdot editors) have noted, it's not like he's got some inside line to CmdrTaco's desk. He just finds himself at the right place at the right time.
Nonetheless, I recommend continuing to tag his articles with "pigpile", just so's we can keep up.
Re:How black is it? (Score:5, Informative)
Re:anything special? (Score:3, Informative)
Re:How black is it? (Score:2, Informative)
Re:Applications (Score:3, Informative)
No it doesn't. It is obvious that it is not. The process makes the metal black by creating an intricate surface structure on the scale of the wavelengths of visible light. It would look like a shiny metal surface at the centimeter or so wavelengths used by radar. The effect probably peters out somewhere in the infrared.
Re:Applications (Score:3, Informative)
> lasers to take out missiles while they were in the air, someone suggested
> that they make them as shiny (in all spectrums) as possible to reflect rather
> than absorb the military laser.
Doesn't work. The electric field intensity at the surface of the target is so high it exceeds the work function of the material and rips electrons right off the atoms. This creates a plasma layer that efficiently absorbs the radiation.
Re:Obligatory Pigpile Rant (Score:4, Informative)
He adds a link to his blog using "additional references and a picture" (or variants) as the text. This results in him getting higher google rankings for his blog, particularly for "additional references and a picture" (or variants). Note the Related Links at the top right of the Slashdot page for this article. In addition to a standard "slashvertisement", the effects also amount to a "googletisement".
While in ordinary circumstances this could potentially be acceptable, the contents of Roland's blog entries are usually redundant (including the picture) to the very articles he is reviewing in his blog. This amounts to an abuse of the trust provided by the Slashdot community.
Many people warn other slashdotters by adding the tag "pigpile" (for those who have tagging enabled). However, more people use the Greasemonkey script [userscripts.org] that will block Roland's pseudoscientific submissions, which brendandonhue [slashdot.org] posted in a previous Pigpile thread [slashdot.org]. That is why the Pigpile rants are low, not necessarily the holidays.
- RG>
Re:Applications (Score:2, Informative)
Re:anything special? (Score:4, Informative)
The technical meaning of the word "power" is energy consumed or produced per unit time. So a fairly small amount of energy can result in a huge amount of power if it's produced or consumed quickly.
Re:Applications (Score:1, Informative)
If you're interested http://www.espionageinfo.com/Sp-Te/Stealth-Techno
Hardly for car paintings (Score:3, Informative)
"For example, blackening a piece of metal the size of a little finger currently takes about 30 minutes."
And matt black hasn't ever been a favourite car color.
Nothing to see, move along. (Score:5, Informative)
Hit things with enough laser fluence and the surface atoms will move around, and may even be blasted off of the surface. This is the basis of a standard materials synthesis technique, pulsed laser deposition (PLD) [wikipedia.org]. Hit a target with a laser, and collect the ejected material on a nearby crystal.
Anyone who has done PLD knows that the surface of the target gets rough when you blast it. If the target is a metal, and the roughness is smaller than the wavelength of light (nanoscale), it will absorb light - it will be black.
In any case, the article asserts that the "blackness" is a material property and is therefore permanent. Nonsense. Touch it and the surface particles will rub off, leaving behind a shiny metal surface. Further, I'd be extremely surprised if there weren't tons of existing patents on surface modification by lasers. There are certainly tons of academic publications on the topic.
Re:Can it be used for long term archival (Score:4, Informative)
Re:anything special? (Score:3, Informative)
Re:Applications (Score:3, Informative)
Re:Solar collectors (Score:3, Informative)
The black panels absorb and retransmits the light, but since their temperature is far lower than the sun the retransmitted light is lower wavelength (ie infra-red). The glass used (or all glass?) is opaque to infra-red, so the infra-red heat energy is re-absorbed and doesnt escape.
A double glass layer on top is even better for stopping the heat loss since it insulates the inner glass panel from convective currents.
Re:ethz (Score:2, Informative)
Re:How black is it? (Score:1, Informative)
Re:How black is it? (Score:2, Informative)