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."
Does this black metal have any special properties aside from being black? The article mainly talks about other ways of making it black not being as good- is that all this really does?
Um, no. The energy is *drawn* from the outlet at a comparatively slow rate (say, over a period of a few seconds) and then *released* into the laser extraordinarily fast (10^-15 seconds).
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.
I sort of skimmed TFA and the abstract (GASP!), and they made it seem as if they could create nanostructures with different properties based on the frequency, intensity, and duration of a given pulse. While I find it unlikely that they've created something that effectively absorbs basically any sort of radiation, it's likely that with a little tweaking they can get it to absorb specific wavelengths.
Yes. The nanostructures formed by the laser give the metals much more surface area, thereby enabling a catalytic effect. Expect to see this played with much more in inorganic and organometallic labs very soon.
Surely if it absorbed all the light, it would be completely invisible, not black?
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...
I never thought of it on the same plane before but radio wave (electromagnetic light waves) like what would be used in radar and such are a form of light waves. I guess the term "Black" meaning it absorbs light means it is invisible to radar, infrared and everything else that uses something from the light spectrum to operate. Thermal?.
Now I see why the military might be interest in this. It isn't just an alternative to paint.
An older New Scientist article [newscientist.com] on a related technique reports 7 to 25 times less light reflected, compared to optical black paint. NS also reports [newscientisttech.com] on the current laser-based technology.
The black has to be as close as possible to absolute. Otherwise you'll be picked up on scanners from a long way away. You have to make your speedster totally non-ferrous, too, right down to the windings in the Bergenholm.
Since it's the holiday, the usual rants against the article submitter, Roland Piquepaille, have been rather muted. To sum up:
* 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.
Actually, you missed one of the more important aspects of the fourth point:
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.
"It's the wild colour scheme that freaks me," said Zaphod whose love affair with this ship had lasted almost three minutes into the flight, "every time you try to operate one of these weird black controls that are labelled in black on a black background, a little black light lights up black to let you know you've done it. What is this? Some kind of galactic hyperhearse?"
The walls of the swaying cabin were also black, the ceiling was black, the seats-which were rudimentary since the only important trip this ship was designed for was supposed to be unmanned-were black, the control panel was black, the instruments were black, the little screws that held them in place were black, the thin tufted nylon floor covering was black, and when they had lifted up a corner of it they had discovered that the foam underlay also was black."
Seems like the perfect coating for solar panels for hot water. The search has always been for the best heat absorbing surface. This type of coating should be the most efficent coating for heat absorbsion.
"This ultra-intense laser blast creates true 'black metal' from copper, gold or zinc by forming nanostructures at the surface of the metal."
Since when were there only 3 metals known to mankind? The summary blows.
Then you look at the articles.
"The key to creating black metal is an ultra-brief, ultra-intense beam of light called a femtosecond laser pulse. The laser burst lasts only a few quadrillionths of a second. To get a grasp of that kind of speed--a femtosecond is to a second what a second is to about 32 million years."
And:
"Currently, the process is slow. To alter a strip of metal the size of your little finger easily takes 30 minutes or more, but Guo is looking at how different burst lengths, different wavelengths, and different intensities affect metal's properties. Fortunately, despite the incredible intensity involved, the femtosecond laser can be powered by a simple wall outlet, meaning that when the process is refined, implementing it should be relatively simple."
I'm guessing this has to do with etching an intricate structure. Perhaps also that the laser can only be fired at a given rate. None of this is explained at all well.
So i suppose I should be a little angry for my article submissions rejection this morning on this very subject. Maybe Roland is paying Slashdot to post his submissions, whatever the reasons, unlike Rolands little gem here mine did in fact note that the laser creates globules, pits and voids on the nanoscale level that dramatically increase the surface area of the treated metal.
This technology has huge ramifications for chemical reactions that need a catalyst, and also in the area of fuel cells.
Unlike Roland, I actually try to link to the article and not some empty blog. Roland, your technology trends suck. Link to the originating article you fool!
Physorg [physorg.com]
Also, does Roland even have a degree in science? Because he sure doesn't ever seem to have a grasp of the important things in the articles he submits.
I would presume that this is a very thin portion of the surface, since there is no data given, and that it sounds like it heats the metal to a vapor (maybe plasma?) and allows it to cool so quickly that it "freezes" in microstructures (excuse me - nanostructures). For all soft metals, then, a simple scratch would reveal the shiny surface free of the effects below the new "coating". Also, a surface with near zero emissivity and high conductivity would likely cause burns very quickly if left in the sun on a summer day. How would you like a nice burn from your car should you accidentally graze your spiffy black racing stripe? Also, wouldn't there be a propensity for these nano-strucutures to foul due to a microseive-like effect - collecting all the crud that just floated by? Seems like a nightmare to clean after pollen season.
It certainly does have some applications, and optics seems to be the obvious place. Having an emissivity of (well, they didn't say) 1e-8 would certainly make baffles more efficient.
If the laser can be modulated it could be used to etch a quasi-indestructible CD-ROM kind of media. For example gold or titanium could last a long while.
That's just the reflective layer. If the laser in your CD-R had enough power to burn more than just the dye in FRONT of that reflective layer, you'd have some serious issues...... dummy.
This could hardly be used for car paintings, or any other big surfaces, since: "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.
This "technology" is nothing new. Just a prof trying to make something mundane sound flashy.
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.
What I'm wondering is the question implied by the editor, can this blast be used to make the metal absorb radar waves? Maybe. The thing about reflecting photons is that the same material can be opaque, transparent, or reflective depending on the wavelength of the photons in question. It sounds like this technique makes a very good black for optical frequencies. Whether it's also black to radio waves needs to be investigated.
> Whether it's also black to radio waves needs to be investigated.
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.
The article mentions needing no more power than is available from an electrical socket.... Assuming you could then also battery power it, you'd have the potential to vandalize any bare metal in public with black marks that are "impossible" to rub off...
Who says it's impossible to rub off? It's a very thin surface treatment. A quick rub with sandpaper should remove it to ordinary metal. And no reason you coudn't paint over it. Actually paint might adhere better to a fuzzy surface like this, when repaintin
> On the other side of the coin, back when there was an article about using > 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.
It is, but it also insulates a bit. If you paint something black, it emits and absorbs radiant heat with the properties of the paint, not the metal. This is about making the metal itself black so it absorbs/emits more efficiently.
Since other people have pointed out the fact that this wouldn't burn off or rub off easily, one of the other things that this would have as an advantage over paints and powder coats is that they add thickness to the material in question and this (theoretically, at any rate) would not. That would be a big plus for precision insturments. Especially if it has any oxidation inhibiting properties.
For many, many years we've been able to use lasers to spot-anneal metals, which produces a very dark (though not totally black) mark on the metal while introducing no change at all dimensionally. One area where this process gets used quite a lot is in artificial limbs/implants where the foreign body to be introduced needs to be permanently marked for identification but can have absolutely no sharp edges or anything else that might irritate or damage the tissue. This new process sounds like something similar, although the femtosecond laser angle is kind of new. I'm curious to see how practical it turns out to be, as the few femtosecond lasers I've worked with were *extremely* sensitive to temperature changes.
For those having difficulty reconciling the "entire power output of the US from a standard AC outlet" thing, understand that you are radiating for a ridiculously short period of time, so you can get a very high peak power in that pulse while still having a very low average power usage if you can unload a decent percentage of the entire duty cycle's worth of power in that one pulse. The Nd:YAG machines that I worked with were only 90 watts or so CW (continuous wave), but when you cranked the Q-switch down to a low enough rate, you could get a peak power in excess of a quarter-million watts in each 10 microsecond pulse. 10 microseconds is 10 *billion* times longer than a femtosecond (same comparison: one second to 317 years), so you have the possibility of having staggeringly large peak powers in these really short pulses.
anything special? (Score:4, Insightful)
Re:anything special? (Score:4, Informative)
Parent
Re:anything special? (Score:5, Funny)
Parent
Re:anything special? (Score:5, Funny)
Parent
Re:anything special? (Score:5, Funny)
Parent
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.
Parent
Re:anything special? (Score:5, Funny)
Hint: Think "perfect stealth", not only for planes, but for your car as well. Make that cop toting the radar gun go insane.
Parent
Re: (Score:3, Informative)
Special Properties (Score:5, Funny)
Well, that one property alone makes it excellent for building Ford Model-Ts.
Parent
Re:anything special? (Score:5, Interesting)
Parent
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...
Parent
Re:anything special? (Score:4, Insightful)
Now I see why the military might be interest in this. It isn't just an alternative to paint.
Parent
Mr. H. Desoto (Score:3, Funny)
"true 'black metal'"?! (Score:4, Funny)
This ultra-intense laser blast creates true 'black metal'
Rubbish, true [youtube.com] 'black [youtube.com] metal' [youtube.com]
(sniff... brings back memories of seeing them in '83.)
How black is it? (Score:5, Interesting)
-jcr
Re: (Score:3, Funny)
I know - boring
Re:How black is it? (Score:5, Funny)
Parent
Re:How black is it? (Score:5, Informative)
Parent
Re:How black is it? (Score:5, Funny)
Parent
Re:How black is it? (Score:4, Funny)
Cheers,
J.
Parent
Re:How black is it? (Score:4, Funny)
Parent
Picture (Score:5, Funny)
I really should just go to bed...
DugUK
Hey look the Roland Template Script is back (Score:3, Interesting)
and his additional references [google.com]
"wall outlet" ease of the use (Score:4, Funny)
black (Score:5, Funny)
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: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>
Parent
Meh (Score:5, Funny)
Space-age technology! (Score:5, Funny)
*bows to Mr Adams*
black... (Score:5, Funny)
(and silver, and bronze..)
Solar collectors (Score:4, Interesting)
That's not all (Score:5, Funny)
All metals huh? (Score:3, Insightful)
Since when were there only 3 metals known to mankind? The summary blows.
Then you look at the articles.
"The key to creating black metal is an ultra-brief, ultra-intense beam of light called a femtosecond laser pulse. The laser burst lasts only a few quadrillionths of a second. To get a grasp of that kind of speed--a femtosecond is to a second what a second is to about 32 million years."
And:
"Currently, the process is slow. To alter a strip of metal the size of your little finger easily takes 30 minutes or more, but Guo is looking at how different burst lengths, different wavelengths, and different intensities affect metal's properties. Fortunately, despite the incredible intensity involved, the femtosecond laser can be powered by a simple wall outlet, meaning that when the process is refined, implementing it should be relatively simple."
I'm guessing this has to do with etching an intricate structure. Perhaps also that the laser can only be fired at a given rate. None of this is explained at all well.
This is a big deal for fuel cells. (Score:5, Insightful)
This technology has huge ramifications for chemical reactions that need a catalyst, and also in the area of fuel cells.
Unlike Roland, I actually try to link to the article and not some empty blog. Roland, your technology trends suck. Link to the originating article you fool!
Physorg [physorg.com]
Also, does Roland even have a degree in science? Because he sure doesn't ever seem to have a grasp of the important things in the articles he submits.
May not be such a great idea for consumer items (Score:3, Interesting)
It certainly does have some applications, and optics seems to be the obvious place. Having an emissivity of (well, they didn't say) 1e-8 would certainly make baffles more efficient.
You realise what this means, right? (Score:5, Funny)
Congradulations on a milestone (Score:3, Funny)
Can it be used for long term archival (Score:3, Interesting)
Re:Can it be used for long term archival (Score:4, Informative)
Parent
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: (Score:3, Informative)
Maybe. The thing about reflecting photons is that the same material can be opaque, transparent, or reflective depending on the wavelength of the photons in question. It sounds like this technique makes a very good black for optical frequencies. Whether it's also black to radio waves needs to be investigated.
-jcr
Re: (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: (Score:3, Interesting)
Who says it's impossible to rub off? It's a very thin surface treatment. A quick rub with sandpaper should remove it to ordinary metal. And no reason you coudn't paint over it. Actually paint might adhere better to a fuzzy surface like this, when repaintin
Re: (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:Blackness (Score:5, Interesting)
Parent
Solar (Score:4, Insightful)
Parent
Re: (Score:3, Interesting)
Re:Blackness (Score:5, Interesting)
For those having difficulty reconciling the "entire power output of the US from a standard AC outlet" thing, understand that you are radiating for a ridiculously short period of time, so you can get a very high peak power in that pulse while still having a very low average power usage if you can unload a decent percentage of the entire duty cycle's worth of power in that one pulse. The Nd:YAG machines that I worked with were only 90 watts or so CW (continuous wave), but when you cranked the Q-switch down to a low enough rate, you could get a peak power in excess of a quarter-million watts in each 10 microsecond pulse. 10 microseconds is 10 *billion* times longer than a femtosecond (same comparison: one second to 317 years), so you have the possibility of having staggeringly large peak powers in these really short pulses.
Parent
Re:Blackness (Score:5, Funny)
Parent