New carbon nanotube-metal hierarchical material is 10x darker than Vantablack | Hacker News Reader

New carbon nanotube-metal hierarchical material is 10x darker than Vantablack

pubs.acs.org

101 pointsbookofjoe68 comments

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https://sci-hub.tw/10.1021/acsami.9b08290

Can someone please explain to me the race to the blackest black?

black is the new black

Painting your car in it to avoid lidar

Haha would this even be legal?

Nevermind - it’s not even feasible

https://www.quora.com/Lets-say-Im-a-rich-racer-who-wants-to-...

It can be done for limited production, but it doesn't fully hide from LIDAR

https://www.cnet.com/roadshow/news/bmw-x6-vantablack-paint-c...

From the CNET article:

>> Typically, the lidar unit can spot things from more than 328 feet away.

>> In this case, the company said the darkest of dark BMWs would need to be about 72 feet away before the lasers and ambient light register the moving black hole.

LIDAR is most effective at a distance from the license plate, headlight, and chrome reflective parts of a car. There is a laser absorbing product called VEIL made specifically for reducing these reflections.

https://www.stealthveil.com/faq/

because that ultra-black looks blue? https://www.youtube.com/watch?v=7tVaJVtxMYE&t=0m11s

It can be done and it is legal. In fact, it has been done...

https://www.bmw.com/en/design/the-bmw-X6-vantablack-car.html

With all that flashing and shaking I cannot perceive anything with or without VB. Ads guys today lost their roof completely.

https://www.google.ru/search?q=bmw+vantablack&tbm=isch

I can't imagine the temperature of that car after sitting in the sun for an hour.

Basically the same as a 99% absorbent black.

It radiates more too. The steady state temperature of the steel plates will be the same as white paint, right?

I assume the AC has to work a little bit more during driving though.

Because you want to make it easier for people and autonomous vehicles to crash into you?

I'm not an expert on applications of black stuff, but having ultra black coatings can help get away with complex optical designs where you would have flares or loose resolution to scattered light inside your tube assembly. Also an optical design that's difficult to pull off mechanically may be easier to manufacture if you just use this coatings inside the tube and on the baffling.

While it may or may not be the primary motivation for research, I'd speculate that it's great for making stealth satellites.

vr headsets could benefit: less glare

It's cool.

Oh god. We developed the blackest tshirt in the world. So I know much more about this subject than what is possibly good for my mental health lol

I made a comparison video about the ultra blacks that are freely available https://youtu.be/ElVzQ2M6vh0

Regarding VB and the MIT stuff, they are hi-tech and useful for optical applications like space telescopes.

Interestingly, the creator of Vantablack told me that there are also some export restrictions due to it's possible usefulness in stealth technology where you want to get rid of stray light.

Let me know if you have additional questions

How quickly does it wash out?

I'm wondering if one use could be solar ovens.

Search for MIT's solar sponge.

Well this is certainly bad news for anyone who invested $35k in a vantablack wristwatch: https://www.h-moser.com/en/collection/1801-1200-endeavour-pe...

In my opinion, if you could afford $35,000 for a Vantablack wrist watch, you can afford another $35,000 for this one too haha. I doubt many of those purchasers were on the bubble.

High end watches aren't priced like regular consumer goods; you can resell them for close to (and sometimes more) than you paid for them, so the "cost" is much much less than the price.

What's most interesting about this watch is the steel/vanta combo costs the same as the solid gold version without vanta. Apparently just that small bit of vanta costs more than a large chunk of gold right now.

Not if you pay MSRP; for H. Moser you’ll take a big loss. The material value of the gold is also really small.

It's a bit weird to demonstrate the colour of vantablack by adding a shine to it.

I was thinking the same thing. You can see how they must have felt a black circle on a screen doesn't look too impressive, but this is a rather backwards way of dealing with that. (I would have added shine to the background and watch body but not the face...)

There is a piece of domed sapphire in front of it with an imperfect anti reflective coating.

I thought I had been sent to the wrong web site to be honest.

It is stated to be an order of magnitude better across the broad spectrum than other broad absorbers.

I wonder if there are any narrow bands that it specifically excels at compared to existing materials, and how big the difference is.

There is a graph right at the top of the abstract that shows the reflectance of this new material compared to Vantablack across a number of wavelengths.

This is the relevant graph I think:

https://i.ibb.co/129RQK9/Screenshot-20190915-124224-2.png

They are potentially misleading by connecting the dots in that way. (The classic, it implies data where there is nothing.)

But can the human eye tell the difference?

If we were to shine a light into vantablack in a dark room ~0.04% would be reflected but it would be enough make the object visible. So, it is possible to differentiate both paints in those conditions.

https://petapixel.com/2016/07/25/human-eye-sensitive-can-det...

Somebody went and took a picture of the vantablack car that wasn't set up to make it look dark and showed it appeared to be a dull gray. There's a very high degree of latitude in how you take pictures of something, and the 0% brightness level in the output can be anything you like. The human eye is adaptive, as well, so it probably wouldn't be all that impressive in person either.

The car looked gray because it had a protective coating on top, thus you get some amount of diffuse/specular reflection from the camera's flash and surroundings.

Serious question:

How do these materials both perform against radar?

Will we be seeing them as stealth paints on planes or satellites?

Follow-up serious question: if I paint my car with this stuff, can a policeman tag me with his radar gun? If I wear clothes impregnated with it, would it confuse a "smart" surveillance camera? I'm also thinking if I used it as war paint, a facial recognition cam would probably be awfully confused by what appears to be a hole in my face.

I love this line of thinking!!

Also, if i were to dimple an an entire plane’s body like a golf ball, and paint it with this... how stealthy would that be?

Oh, about as stealthy as a metal golf ball, painted black?

Put it this way: If you shine a flashlight at a cosmetic hand mirror, does the flashlight shine back and hit you in the eyes? Now tilt the mirror so that the flashlight doesn't blind you.

Stealth surfaces are supposed to work like a tilted mirror.

Now imagine a polished chrome golf ball. If you shine a flashlight at it, you'll still catch a bounce from the flashlight reflection, even if the surface is dimpled.

Compare the chrome golf ball's performance to an icosahedron faceted with mirrors. The faceted platonic solid is less likely to shine the flashlight back at your eyes, depending on it's angle of rotation. And a dodecahedron would perform even better.

Thats not exactly accurate. Those nanotube coatings are optimised so it traps the light entirely

For the car case, usually police shoot their radar at your license plate since it's a flat reflective surface anyways.

And at headlights otherwise. But if your car has popup headlights and no front plate, and you paint it vantablack, you'd probably be close to invisible to police LIDAR (laser) guns. I'm not sure what the reflectivity of this stuff in the radio spectrum is though.

Do the black and yellow California plates still possess reflective properties?

Just send the "reflection" back at the donuts connoisseur before the real reflection does and your objective has been reached. Ready made devices for exactly this purpose exist and are dirt cheap. While we're at it, the photonic equivalent can be beaten by means of special reflective coating. One that whites out the entire photo using the received "flash". Needless to say, this is also widely available & dirt cheap.

Id like a baseball cap, painted with vanta black, but with a cheese-cloth style net also painted with vanta black, which can be worn down like a bee-keepers hat, such that facial recognition cant be used against me.

Also, i am anouncing right now my freedom to destroy any facial recognition cameras i come across. Its my fist amendment right to not be supressed with facial recognition because i am free to say anything i want, and using facial recognition is a violation of my first amendment rights.

https://worldbuilding.stackexchange.com/questions/76278/woul...

google my friend. There are other specially formulated paints that aim to absorb the correct wavelength.

Awesome read, thank you

Now I’m envisioning a system where the spy drone sows down significantly and little machanized graphene “hairs” stand up all over its body to absorb any wavelengths of radar it wants to avoid...

What are the hopeful uses for making ever more absorbing black materials?

reducing stray photons in instruments, you only want those that go through your lens array, not those bouncing off the housing.

It would be interesting to test performance of a single fibre optic thread pulled through and coated with this to see the performance output.

I'll lay down a guess that having a better understanding of EM spectrum absorption -- in any wavelength -- likely has all kinds of applications. Better stealth technology, improved shielding for EM emitters, and possibly improved reflectors as well.

If it emits in near IR it will make a perfect conversion medium for silicon solar cells.

While not the most technology advanced use, I think this stuff could make for a great solar powered water heater.

Very important these days. Depending on full cost of this material.

Are the incremental improvements over regular black paint meaningful?

the inside of telescopes (and other optics)

trolling Anish Kapoor?

Could such a material be put behind (and be protected by) glass and still have the desired properties?

O wonder if they could use this to absorb sun light and transform into heat and generate electricity. Looking into the absorption rates in the chart, it’s clear that it would be 30x more efficient than solar panels these days.

solar panels are way more efficient than 3.333... % , so no, nothing can be 30x more efficient than solar panels these days.

For heating a surface you'll want a material that absorbs the solar spectrum, but is extremely reflective on the heat spectrum. Optimizing the material absorbtivity does not lead to much gain, while optimizing the reflectivity leads to huge results.

This material absorbs every spectrum, what makes it really bad for that application.

Maybe we now can get true black on an LCD screen?

LCDs don't work like that, they block the back-light with polarization:

http://soft-matter.seas.harvard.edu/index.php/Phase_transiti...

Maybe truer black on OLED screens, if OLEDs can be printed on a back plate like that.

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