Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!

 


Forgot your password?
Close
typodupeerror
×
Science Technology

Blacker Than Black 449

Posted by michael from the chocolate-so-dark-light-cannot-escape dept.
An anonymous reader writes "British scientists at the National Physical Laboratory in London have invented the darkest material on Earth. 'It could revolutionise optical instruments because it reflects 10 to 20 times less light than the black paint currently used to reduce unwanted reflections. The key to the nickel and phosphorous coating's blackness is that its surface is pitted with microscopic craters.' Wonder how effective it would be as a solar heating surface ?"
This discussion has been archived. No new comments can be posted.

Blacker Than Black More

Blacker Than Black

Comments Filter:

  • What's blacker than black... (Score:2, Funny)

    by Anonymous Coward
    What's blacker than black... ...a new nickel and phosphorous coating with microscopi...

    You know? The joke just isn't as funny this way.

    • Re:What's blacker than black... (Score:4, Insightful)

      by Spock the Baptist ( 455355 ) on Thursday February 06, 2003 @09:10AM (#5240018) Journal
      Humm....

      It's obvious that it's highly non-reflective in the visible portion of the spectrum, the question is how "black" is it in other spectrum regimes. Is it equally black in the IR, and/or UV?

      Also, remember that a good absorber is a good emitter.

      • Re:What's blacker than black... (Score:4, Informative)

        by Raiford ( 599622 ) on Thursday February 06, 2003 @12:21PM (#5241923) Journal
        A little physics awnsers this. No ! If the surface is optically rough as resulting from these little microcraters then internal specular reflection will only occur for wavelengths smaller than the crater size. Diffraction will occur as you get to sizes on the order of the crater size and just plane old specular reflection from a rough surface will occur for wavelengths larger than the crater size. This is a simple explanation but it captures the idea of how this kind of thing works. If the material already has a fairly high intrinsic absorptivity then multiple internal reflection will cause the effective reflectivity to be extremely low. Longer wavelengths will have a tendancy to not even see the little craters and probably give a higher reflectivity. There are things that make the problem more complex. There are most likely a distribution of crater sizes that interact differently with the incident light and the intrinsic absorptivity of the material is most likely dispersive (dependent on the wavelength of the incident radiation).


    • A slightly more informative article is here [newscientist.com].

      They give the recipe.

  • Comment removed (Score:4, Interesting)

    by account_deleted ( 4530225 ) on Thursday February 06, 2003 @08:18AM (#5239672)
    Comment removed based on user account deletion

    • Re:Wonderment (Score:5, Insightful)

      by Anonymous Coward on Thursday February 06, 2003 @08:24AM (#5239727)
      Wonder how effective it would be as a solar heating surface ?

      It wouldn't make much difference, because changing from absorbing 97.5% of the sunlight to 99.65% isn't going to change the economics of your solar collector much.

      However if you are building a telescope and you want to reduce the stray reflections, going from reflecting 2.5% to reflecting 0.35% is a huge improvement
    • Blackbird the plane? SR-71?

  • Solar heating! (Score:5, Funny)

    by keller ( 267973 ) on Thursday February 06, 2003 @08:19AM (#5239677)
    Wonder how effective it would be as a solar heating surface ?

    I would say that the solar surface is hot enough as it is!

    • Well... in physics, the sun is often used as an example of a "black body", so one may even say it's black enough as it is ;-)

      • Is it? I was under the impression that the chromosphere kindof messed that up a little. Oh, and the Sun isn't in thermal equilibrium with anything. Actually, I suppose its own gravitational energy counts (over sufficiently short timescales)...executive decision? OTOH phenomena such as sunspots and other surface effects remove any homogeneity from the radiation, and don't forget the solar neutrino emission which is unlikely to be in thermal equilibrium.

        Typically, black bodies are approximated by hollow ceramic ovens with a gold lining. The oven has a small hole in the side and is heated to the melting point of gold Thus you know exactly the temperature of the sides of the oven, you make the hole small enough that effusion doesn't upset the thermal equilibrium, et voila you have a blackbody standard.

  • And with one fell swoop.... (Score:5, Funny)

    by CHUD-Wretch ( 578617 ) on Thursday February 06, 2003 @08:19AM (#5239678) Journal
    Goths just got scarier. "Black as night, faster than a shadow" -Judas Priest- "Hell Bent For Leather"

  • 10 to 20 times less? (Score:3, Funny)

    by Anonymous Coward on Thursday February 06, 2003 @08:19AM (#5239680)
    If it reflected one times less that'd mean it was reflecting nothing at all, so what happens when it reflects 10 times less?
    • What?

      Look, it's simple. 'Black' paint would normally reflect a small amount of light. This new stuff reflects 1/10 times that amount.
  • Need I say more?

  • black (Score:5, Interesting)

    by qoncept ( 599709 ) on Thursday February 06, 2003 @08:20AM (#5239688) Homepage
    My high school physics teacher had a piece of "black," though not as black as this. He said he'd put it against walls and students sitting at the other end of the room would think there was a hole, he said. By the time I saw it, it was old and had gotten too dusty to be very impressive.

  • The name (Score:5, Funny)

    by e8johan ( 605347 ) on Thursday February 06, 2003 @08:20AM (#5239691) Homepage Journal

    Why don't they name materials better today? What is interesting in the name "Super-black"? Nothing!

    I suggest we call it Darkonium or something...

  • How much more black could it be? (Score:5, Funny)

    by gibber ( 27674 ) on Thursday February 06, 2003 @08:21AM (#5239699) Homepage
    None.

    None more black.

    • Re:How much more black could it be? (Score:5, Funny)

      by swordboy ( 472941 ) on Thursday February 06, 2003 @08:41AM (#5239841) Journal
      In the Beginning, there was Nothing. And then God said, let there be light.

      And there was still nothing. But - hell - you could SEE it!
    • How much more black could it be?

      :-)

      I think the term originally comes from Television, where you can get Blacker than Black, as the actual signal level for black is higer than the absolute lowest value. Ever done the calibration where you have to lower/raise the brighness so that a black areas is the same colour as the background? There is a test image and a description of the process here [pacificnet.net].

      Highly recommended if you like things to be "just right" ;-) Most folk have their TV set very wrongly and don't realise it, usually because they have the settings up in the shop to make it stand out from the other ones.

      If you are interested in this sort of thing, and have a home cinema set up, I highly recommend the Video Essentials [videoessentials.com] DVD, which explains everything about setting your system up to be perfect. No, I don't work for them!

  • Spinal Tap's next album (Score:5, Funny)

    by micromoog ( 206608 ) on Thursday February 06, 2003 @08:21AM (#5239703)
    NIGEL: I think he's right, there is something about this, that's that's so black, it's like; "How much more black could this be?" and the answer is: "None, none... more black."

  • Sandpapered (Score:5, Funny)

    by Big Mark ( 575945 ) on Thursday February 06, 2003 @08:22AM (#5239709)
    "The key to the nickel and phosphorous coating's blackness is that its surface is pitted with microscopic craters"
    Not much different from going over it with the world's finest-grain sandpaper, then. And...
    From the article:

    "When you look at the black, it is an incredibly beautiful surface. It's like black velvet."
    Ah, so that's why they made it. The physicists are secret cross-dressers, after the finest frocks known to man!

    -Mark
    • "When you look at the black, it is an incredibly beautiful surface. It's like black velvet."

      Great. Now all the flea markets are gonna be stocked with Elvis paintings on this!

  • fuligin? (Score:2, Informative)

    by Black Parrot ( 19622 )


    OK, now we know what fuligin [pannis.com] is made of.

  • Espionage (Score:2, Interesting)

    by amigaluvr ( 644269 )
    I wonder how this could be used for espionage

    Especially if instead of just light it also doesn;t reflect other things like signals. Electricity and EMP and radar and somesuch.

    'Dark matter' used for 'Dark purposes'.

    Of course it could revolutionise things in other ways I believe those will be the first purposes this material is used for.

    Imagine the potential in laptop LCD screens however.

  • Does this mean... (Score:5, Funny)

    by OneBarG ( 640139 ) on Thursday February 06, 2003 @08:23AM (#5239719)
    ...the Man is gonna hold it down more than any other material?

  • Nifty. I wonder how long... (Score:4, Funny)

    by idontgno ( 624372 ) on Thursday February 06, 2003 @08:24AM (#5239724) Journal
    before the substance and its application process trickle down to amateur telescopy?

    Nigel Fox, who heads the optics group at NPL, said: "When you look at the black, it is an incredibly beautiful surface. It's like black velvet."

    Who'll be the first schmuck to paint Jesus or Elvis onto this surface?

  • The light that is neither transmitted nor reflected is absorbed. If it is totally opaque too it has to be also a good solar heating surface. That said, one might be a very good absorber at particular wavelengths, but transparent or reflective at others. The cavities should act as a blackbody and operate at a wide range of frequencies though.
  • Is this a material that Ford and Zaphod will marvel at as they cruise space parks looking for a ship to steal and will Marvin be riding a ship made of one into the sun.

    Rest In Peace Mr. Adams
  • Hotblack wants to upgrade his spaceship with some new buttons.

    Rob.

  • New? but I saw 2001: A Space Odyssey ... (Score:3, Funny)

    by Radioheadhead ( 611950 ) on Thursday February 06, 2003 @08:25AM (#5239733) Homepage
    so I know this material has been here on earth since the "Dawn of Man."

  • amature astronomy (Score:5, Informative)

    by Njerd ( 580768 ) on Thursday February 06, 2003 @08:27AM (#5239743)
    I would love to see this used to coat the vanes that support the secondary mirrors of reflector type telescopes. Diffraction spikes (the little spikes on relatively bright stars) are really the reflection of light on these little supports. If you are into photographing nebulae, having a bright star in view can be a real photo killer.

  • black velvet (Score:3, Funny)

    by Keith_Beef ( 166050 ) on Thursday February 06, 2003 @08:27AM (#5239747)

    From the lame Ananova article:

    It's like black velvet

    I thought that black velvet was 60% Guinness and 40% Champagne...

  • Think of it Linux geeks. A car that's so black, you can't tell how close you are standing to it. Inside all of the controls will be black on a darker shade of black.

    Might make a cool screen too.

  • Just turn out the lights, drink a few dozen beers, or even just close their eyes?

  • Martin Black (Score:5, Informative)

    by mikeselectricstuff ( 556110 ) on Thursday February 06, 2003 @08:29AM (#5239761) Homepage
    The book 'The Hubble Wars' mentions a coating called 'Martin Black' developed by Lockheed-Martin for use in spy satellites - I wonder how this stuff compares. I found some info Here [umsystem.edu] : The 'Martin Black' is not a paint at all, but a specially etched aluminum surface that acts like an anechoic chamber on a microscopic scale. The surface looks like an array of very steep pyramids a few wavelengths of light apart. It's extremely fragile & expensive to produce, but was never a classified process. Mostly used in aerospace optical hardware such as star trackers & imaging systems that have to work in direct sunlight. Ball Aerospace has a version of this process. It's considered to be a 'proprietary' process, ie they won't tell you how it's done for commercial reasons.
  • light absorbtion prop-PER-ties!

    An' I'm Supa-Black! UNGH!

    Hawt! :)

    ala SuperBad

  • A Tad more detail (Score:5, Informative)

    by dmontreuil ( 464940 ) on Thursday February 06, 2003 @08:30AM (#5239771)
    There's a little more detail and a few pictures at http://www.npl.co.uk/optical_radiation/superblack. html

  • Future work (Score:5, Funny)

    by Wrexen ( 151642 ) on Thursday February 06, 2003 @08:32AM (#5239785) Homepage
    Scientists estimate this will be the blackest material ever manufactured, until they perfect the technique of mass-producing Hillary Rosen's soul.

  • Mom! Dad! (Score:5, Funny)

    by Degobah ( 523323 ) on Thursday February 06, 2003 @08:32AM (#5239787)
    Don't Touch It! It's Evil!
  • With the light source at right angles, the coating reflects less than 0.35%. Black paint reflects about 2.5% - seven times more.

    This kind of things could decrease utility, or make possible uses more difficult?

    • "Why in certain angles?"

      My half-assed guess is that it's a property of the craters. At the proper angles, the light that doesn't get immediately absorbed is reflected to another part of the same surface. So instead of reflecting x% of the light hitting the surface, it reflects x% of x%.

  • There are going to be some happy goths! (Score:5, Funny)

    by RHIC ( 640535 ) on Thursday February 06, 2003 @08:35AM (#5239806)
    Well, now all those people wearing t-shirts saying "I'm only wearing black until they invent something darker" will be very happy! Any idea as to when we'll be able to get it in t-shirt form?

  • Well... (Score:5, Informative)

    by caveat ( 26803 ) on Thursday February 06, 2003 @08:35AM (#5239807)
    ...this is a Good Thing for production instruments, but it won't matter much for research/labwork/prototypes; right now I'm working on laser detection of single atmospheric particles; we needed a *black* coating for the inside of the chamber, but it didn't need to be particularly robust, just dark - so we smoked it with a flame. Carbon black is the least reflective substance known, IIRC it absorbs something like 99.996% of incident radiation...anybody who's seen the inside of an old kerosene lamp chimney knows exactly what they mean in the article when they talk about the 'black velvet' appearance. We did have some problems with it 'popcorning' as we pumped the chamber down, but a staged evacuation with good degassing periods took care of that.

    Oh, this would make a great solar heating material - somebody mentioned the specific heat of the material, but as long as you have a thin layer backed by a heatsink, the specific heat doesn't matter (it's just the amount of heat a material can contain per gram; if you have just just a tiny bit of black substance, it doesn't matter how much heat it stores); it's all about the absorbtion.

    • Re:Well... (Score:3, Funny)

      by GT_Alias ( 551463 )
      We did have some problems with it 'popcorning' as we pumped the chamber down, but a staged evacuation with good degassing periods took care of that

      Oh man...the potential. Too bad I don't have a sense of humor.

  • I see a telescope and I want it painted black... (Score:4, Insightful)

    by wowbagger ( 69688 ) on Thursday February 06, 2003 @08:35AM (#5239808) Homepage Journal
    I have to wonder how well this surface approximates the perfect "black body" in physics. Since a black body is the perfect radiator as well, this could be useful not only in making better telescopes, but also in better radiating heat away from satellites.

  • "Wonder how effective it would be . . . (Score:3, Insightful)

    by kfg ( 145172 ) on Thursday February 06, 2003 @08:36AM (#5239810)
    as a solar heating surface ?"

    Ummmmm, much more than black paint?

    I don't mean to be snide or anything ( for a change), but you really couldn't figure that out for yourself in about 1/10 of a second?

    Not that it'll make much difference in a world that still puts black asphalt products on their roofs (which does everything wrong, being hot in summer and cold in winter) instead of polished aluminum.

    In order to make good use of solar radiation one must first learn to use it *properly,* no matter how efficient any particular material is. Otherwise that efficiency just goes to waste.

    I recommend a perusal of Rex Robert's classic work "Your Engineered House" for an explaination of how understanding basic thermodynamics can be applied simply and cheaply, with off the the shelf non-propriatary building materials, to a house with remarkable effect.

    Just as in software no one makes gobs of money promoting nonpropriatary solutions, even though those solutions may not only be cheaper, but *better.* The whole Open/Propriatary thingummy goes far deeper than the IT industry. It is pervasive in every walk of life.

    It's up to you to ignore the advertising material and edumicate yourself I'm afraid.

    KFG

  • Materials Science (Score:5, Interesting)

    by JumpingBull ( 551722 ) on Thursday February 06, 2003 @08:44AM (#5239865)

    This will prove to be useful, for two reasons:

    First, it is a better absorber then what we have now, which, as someone pointed out, would make an incremental improvement for things such as solar collectors.

    Second, it may find some powerful uses as a black body emitter, which would have some applications for cooling. Specifically, there is a window in the atmosphere where energy can leave the atmosphere ( around one of the IR ammonia lines, IIRC) this may alleviate the greenhouse effect ... maybe ...

    As one of my Professors used to say "Progress is measured by progress in Materials Science". He might have been biased, however...

    I would be very interested to find out the wavelengths where this is effective.

    There are three types of reflectance that I am aware of: mirrors; diffuse reflectors (lambertian surfaces) and a special case of reflectance as found on a dusty surface, such as the moon( which is an aggragation of spherical lambertian surfaces, with special properties). Anyone else know of any others?

    • this may alleviate the greenhouse effect ... maybe ...

      I'd rather hope not

      As my old Professor used to say "its the ENHANCED Greenhouse Effect thats the environmental problem, the normal Greenhouse Effect is what keeps us alive"

      If our Atmosphere didn't 'trap' a certain amount of the incident energy from the sun, and the Oceans didn't transport this around the surface then out little planet would resemble a snowball.

      This is what happens in an ice age when the Ocean/Atmosphere system flips into another metastable state and the large amount of ice and snow on the surface significantly changes the reflective properites of the planet and the whole system cools.

      First we need to understand how this delicate balance actually works before we try and fix it. One thing we are learning is that the Ocean/Atmosphere system is not the safe stable thing we assumed it was, but its very dynamic with a number of metastable states. It can and has switched between states on a geologically quick (5000 years) timescale without much provocation. The bad news is that sustaining life is easy in the current state, it gets much harder in some of the others.

      Like a pH buffered solution its quite possible that our environment can tolerate and compensate for all the stuff we chuck into it, and then suddenly flip to another state.

      Oh, and the increment improvement in absorbtion will do very little to help solar collectors - the problem with solar collectors is doing something useful with the heat once you've got it, not getting it in the first place. Find me a material thats twice as good as a thermocouple than current technology and we may be on to something...
  • So what's the cost going to be like, and how's the weight? Googling, a couple of articles specifically say it's for the space industry. Must be a cost thing? What's to keep this out of my next Swarovski spotting scope?

    (Not that the return for cost will be there in consumer optics, but that never stopped those of us with $1000 phase coated, nitrogen purged roof prism binoculars before... We're too easy.)

  • The key to the nickel and phosphorous coating's blackness is that its surface is pitted with microscopic craters.

    Pitting the surface with microscopic black holes will make it even blacker.

    Besides, it will absorb everything (including matter, not only energy!) very well - good for cleaning industry.

    two thing to solve before: how to make microscopic black holes (perhaps in a process of cold fusion?) and how to keep them together (perhaps with dark matter?).

    Wait a minute, what is the color of dark matter? Is it black or it's grey a bit?

  • Solar heating (Score:3, Informative)

    by Paul Johnson ( 33553 ) on Thursday February 06, 2003 @08:51AM (#5239909) Homepage
    This will be (almost) no better for absorbing heat than conventional matt black.

    Say conventional black paint reflects 1% of the radiation. This stuff reflects, say, 0.1%. If you are building optical instruments then that is a 90% decrease in ambient reflections from internal surfaces, which is really useful.

    But if you are interested in harvesting energy then the absorbancy has gone up from 99% to 99.9%, which is an increase of just 0.9% over what we had before. Gee.

    Paul.

  • That would make a cool case mod. A really black PC that looks more like a hole with a glowing blue led in the center. With it being so black you cant makeout its actuall shape.

  • short on details (Score:2, Interesting)

    by syle ( 638903 )
    Why are all the articles I see on Ananova so short on details? They amount to 'Someone told us that XXX exists!! Cool!'

    Here [ananova.com] is another example.

  • reminds me of that black stunt ship (Score:5, Funny)

    by option8 ( 16509 ) on Thursday February 06, 2003 @09:02AM (#5239969) Homepage
    i hope douglas will excuse this:


    . . .

    Zaphod's attention however was elsewhere. His attention was riveted on the ship standing next to Hotblack Desiato's limo. His mouths hung open.

    "That," he said, "that ... is really bad for the eyes ..." Ford looked. He too stood astonished.

    It was a ship of classic, simple design, like a flattened salmon, twenty yards long, very clean, very sleek. There was just one remarkable thing about it.

    "It's so ... black!" said Ford Prefect, "you can hardly make out its shape ... light just seems to fall into it!"

    Zaphod said nothing. He had simply fallen in love.

    The blackness of it was so extreme that it was almost impossible to tell how close you were standing to it.

    "Your eyes just slide off it ..." said Ford in wonder. It was an emotional moment. He bit his lip.

    Zaphod moved forward to it, slowly, like a man possessed - or more accurately like a man who wanted to possess. His hand reached out to stroke it. His hand stopped. His hand reached out to stroke it again. His hand stopped again.

    "Come and feel the surface," he said in a hushed voice.

    Ford put his hand out to feel it. His hand stopped.

    "You ... you can't ..." he said.

    "See?" said Zaphod, "it's just totally frictionless. This must be one mother of a mover ..."

    He turned to look at Ford seriously. At least, one of his heads did - the other stayed gazing in awe at the ship.

    "What do you reckon, Ford?" he said.

    "You mean ... er ..." Ford looked over his shoulder. "You mean stroll off with it? You think we should?"

    "No."

    "Nor do I."

    "But we're going to, aren't we?"

    "How can we not?"

    . . .


    offtopic, yes, but somewhat more in the vein of discussion, how does it do on reflecting, say, radar?

  • I reckon positive environmental projects like solar heating for developing countries won't get a look in.

    If it really is a useful low-reflecting material, the Official Secrets people will slap a secrecy and Military Secret stylee order on the whole lot and the only time we'll see the stuff (pun intended :-) ) is on UK military equipment. Oh, and US military as well, seeing as Tony is trying his damndest to make us the 51st State these days....

  • Metallica (Score:2, Funny)

    by gregRowe ( 173838 )
    great, as soon as Lars Ulrich gets word of this they'll re-release their black album for more profits.

  • Solar Power. (Score:5, Interesting)

    by miffo.swe ( 547642 ) <daniel...hedblom@@@gmail...com> on Thursday February 06, 2003 @09:11AM (#5240026) Homepage Journal
    The problem with solar power today isnt about efficiency since modern panels have about 70-80% efficiency in heating water. The incoming power is about 1000W per m2. A better absorber wouldnt make the panel that much more efficient.Chromium Oxide have an efficiency of about 92%. Much of the problems lie in how you transport the heat from the panel to the energy storage.Insulation of the panel is something that you have to take into consideration. Cost is also of utter importance since you often have a roof capable of housing more than 30 m2 of panels which in most houses is overkill. To generate water you typically would need about 5 m2 from mars to november.

    If this material can make the total cost smaller then its good but if it makes it more expensive it isnt of any use. Robustness and price is what we should look into and not efficiency. A cheap solar panel that lasts for as long as it have to be functional to return the investment is possible today.

    The main problem with solar power is that when you need the power most (night/winter) there arent much sun around. Solar Power can never be anything but a valuable complement to something else. All trials of storin the energy longer times have failed miserably so far.

    Im not just rambling here, i was a partner in a company manufacturing solar panels some years ago.
  • One of the early applications might be on star-trackers

    Was I the only one who read this as star-trekkers the first time?

  • How Black Is It? (Score:5, Funny)

    by Greyfox ( 87712 ) on Thursday February 06, 2003 @09:13AM (#5240043) Homepage Journal
    Blacker than the mood of a web master who just found out that his page was posted on slashdot.
  • Back in Blacker than Black

    AC/DC should really rename their Back in Black album now.
  • OK. So this thing is blacker than Dick Cheney's heart, but I have a serious question. First, I know shit little about physics (but plenty about what-not, what? what?). So, can a super black material attract light just by being super black? I mean, if the light is not directly shined upon it, then does a super black material pull "indirect" light toward it? I await your answers/flames/non-sequiturs with baited breath.

  • Zinc Cloride (Score:2, Interesting)

    by hottoh ( 540941 )
    HCl acting on Zinc plate can produce a very black surface. In about 1980 I experienced the chemical effect and read about it. The article I read had a microscopic view of its surface and it indeed had striking peaks and valleys.

    The intent was to use it in cameras in to enhance the already black shrouds fore of the camera lenses in space.

    It was very odd looking at something so black.


  • The question is how much more black could it be? The answer is none... none... more black.

  • This the stuff Hotblack Desiato's ship is made from in Restaurant at the End of the Universe.
  • This reminds me of the classic I'm so goth-list [geocities.com]...

    I'm so goth my black is blacker than your black. I call it "black black."

    I'm so goth, I don't say "black," I say "blahhwwwkkk."

    I'm so goth I have actually seriously uttered the phrase, "the darkest dark of the dark darkness."

    My favourite one is a bit off topic but it has to be mentioned.. ;)

    I'm so goth that bats hang little plastic me's from their ceiling.

  • I hope whoever is doing this doesn't go into genetic engineering.

    Imagine turkeys with white meat, dark meat, and SuperBlack.

    Oh wait, I left the oven on for too long.

  • Why don't they take a picture and put it online so we can see how black it is?

  • Here's a picture of it (Score:5, Funny)

    by Conspiracy_Of_Doves ( 236787 ) on Thursday February 06, 2003 @09:43AM (#5240302)
    Super-black [state.mn.us]

  • "Martin Black" has been available for years (Score:4, Informative)

    by mfago ( 514801 ) on Thursday February 06, 2003 @10:10AM (#5240567)
    Martin Marietta (now Lockheed Martin) has produced a proprietary "super black" coating for years now. I've seen it, and it is _very_ non-reflective. The coating mentioned in the article sounds similar.

    "Martin Black" is proprietary though, so if you want a part coated you have to send it to Lockheed.

  • To get it darker... (Score:4, Interesting)

    by MickLinux ( 579158 ) on Thursday February 06, 2003 @10:56AM (#5241059) Journal
    To get it even darker, plate a bunch of razor blades with this material, and then stack them.

    My father used stacks of razor blades as a heat dump for lasers in his fusion research at University of Wisconsin.

    He showed with pencil and paper how the razor blades successively reflect the light into the gaps between the blades, without turning it around. Thus, they absorb all the light, and make a great blackbody.

    Just as an interesting note: This was back in the early 70's, at a time when cost-efficient fusion was only a decade away, and had been only a decade away for 20 years. As part of his defense, he was asked whether it would be practical any time soon. His answer was no. When asked why, he pointed out that the reaction that was giving them some success was the D-T reaction, and that Tritium was so rare that it would never be a practical fuel.

    That essentially did not earn the pleasure of others in the field, and kept him out of that field -- perhaps a blessing, since success might have doomed his life to failure.

  • Jack London, "The Shadow and the Flash" (Score:3, Informative)

    by dpbsmith ( 263124 ) on Thursday February 06, 2003 @10:58AM (#5241077) Homepage
    There's an amusing story by Jack ("Call of the Wild") London entitled "The Shadow and the Flash." It's one of about a dozen stories he wrote that would be categorized as science fiction had the genre existed then.

    Two competitive brothers both seek the secret of personal invisibility via divergent, and completely bogus methods. One of them finds some way to make his entire body perfectly transparent (!) in the belief the perfect transparency equals invisibility, and apparently gets his index of refraction close to unity but still has some dispersion, because although he is invisible, he produces telltale rainbow-colored flashes.

    The other one searches for a perfect black, in the even stranger belief that an object covered in perfect black reflects no light and is therefore invisible. According to the story, this works except that, of course, he casts a shadow--and when he's present, even when not casting a shadow his presence creates an ill-defined sense of darkness or gloom.

  • More info about composition (Score:3, Informative)

    by mattr ( 78516 ) <<mattr> <at> <telebody.com>> on Friday February 07, 2003 @03:02AM (#5248769) Homepage Journal
    More info here [newscientist.com] mentioning composition, of which I'll quote just a part (see the article for a graph and mention of applications):

    Stalagmites and craters

    By examining the surface of hundreds of alloy plates under an electron microscope, NPL has discovered where previous researchers went wrong. It has developed a two-stage technique that produces the blacker black New Scientist saw emerge from the acid tank last week.

    In the first stage, an object to be blackened is immersed for five hours in a solution of nickel sulphate and sodium hypophosphite. This produces a nickel and phosphorus coating containing between five and seven per cent phosphorus. Then the surface is etched with nitric acid to produce the super-black surface structure.

    One of the crucial discoveries, says Brown, was how the percentage of phosphorus in the nickel coating affected the surface after etching. An electron micrograph of the surface of an alloy containing more than eight per cent phosphorus (see graphic) looks like a collection of stalagmites.

    But if the phosphorus content is around six per cent the surface becomes pitted with craters. The curved craters reflect less light that the straighter-sided stalagmites, so super-black reflects about half as much light as the high-phosphorus surfaces.

    Right angle

    Super-black is especially effective at absorbing light that hits it at an angle. With the light source at right angles the super-black coating reflects less than 0.35 per cent. Black paint, by comparison, reflects about 2.5 per cent, or seven times as much. With the light source at an angle of 45, black paint reflects 25 times as much light as the super-black.

    And.. they've been working on it for a while, here is text from their 2000 lab review pdf [npl.co.uk].

    NPL Super Black In order to make accurate measurements in the UV, IR and visible regions, optical instruments and sensors need surfaces with very low reflectance. These black surfaces are used as efficient radiation detectors or may reduce stray light in an instrument. Highly efficient black surfaces allow smaller, lighter instruments to be made, which is an important advantage in aerospace applications. NPL has successfully developed a very high quality optical black ] known as NPL Super Black. The process uses an adapted nickel phosphorus electroless plating technique followed by finely controlled etching and gives probably the blackest surface known in the visible region. NPL has successfully and repeatedly produced the Super Black coating on a small-scale ecottage industryf basis for a number of years. It is now for upgrading and validating the process for plating much larger substrates with this high quality optical black. The upgrade has led to an opportunity to collaborate with CNES, Astrium and Sodern, the major space contractors for the European Space Agency, on the space evaluation of the black. If successful this will open up many new opportunities for supplying coated optics to the aerospace industry.

Slashdot Top Deals

A committee takes root and grows, it flowers, wilts and dies, scattering the seed from which other committees will bloom. -- Parkinson

Close