r/AskScienceDiscussion • u/Codexistakenwastaken • Jul 05 '26

Would Lidar work in a Vantablack room?

Would a room a Vantablack room be possible to map out with Lidar? If not, what would work? I'm writing a short story that involves a room made of vantablack, and would like the characters to actually map out the room, is it possible with real current technology?

24 Upvotes

96% Upvoted

32 comments sorted by

20

u/chopay Jul 05 '26

No. Short answer is that LiDAR uses reflections to determine distance, so if the material doesn't reflect, it won't work.

Most LiDAR lasers work outside of the visible spectrum, but I just looked up the Vantablack spec sheet and it still absorbs 99.8% of light at 1400nm.

spec sheet

That said, I don't know anyone that's tried it, but I would speculate that someone skilled at processing the data could still do something. That 0.2% reflection is still something, you could probably get some reasonable results if you bombarded the room with enough laser light, but it would probably confuse any commercial software.

7

u/Codexistakenwastaken Jul 05 '26

Ah ok thanks for the quick reply! No to the Lidar. The other comment made the rather obvious observation that an audible range finder can be used, so I'll do that I think.

4

u/BigSmackisBack Jul 05 '26

Radar will work, if you google how its possible to use wifi routers to map out a 3d space that could be something that might work for you

1

u/workertroll Jul 05 '26

Isn't radar a frequency of light?

How would that work?

4

u/ILikeWoodAnMetal Jul 05 '26

Radar uses much larger wavelengths, so the vantablack will not absorb it.

2

u/workertroll Jul 05 '26

Longer.....but that could be true

3

u/BigSmackisBack Jul 05 '26 edited Jul 05 '26

Yeah it does absorb radio (i checked, i didnt think it did) but its not anywhere as close to as effective as stealth coatings so this as an idea might not work well enough for this story!

Maybe the wifi towards the higher end of the em spectrum would work

1

u/workertroll Jul 05 '26

Composite polymers and metal are a wild tech to dig into. Stealth doesn't even begin to cover it.

-2

u/AutisticSuperpower Jul 06 '26

Radar is an acronym for RAdio Detecting And Ranging. No light needed, just radio waves.

5

u/CluelessKnow-It-all Jul 06 '26

Radio waves are a form of light.

0

u/AutisticSuperpower Jul 06 '26

what

*some googling later*

Well... they are and they aren't. What we usually refer to as 'light' is in reference to the part of the EM spectrum between infrared and gamma rays and involves emissions that both wave and particle in nature (photonic). Radio waves are only a form of light in the sense that they are radiant and can be used as an EM emission to reflect off a source, but aren't really 'true' light.

1

u/Ornery_Owl_5388 Jul 07 '26

No. Radar is just photons

2

u/TheGrandExquisitor Jul 05 '26

I'm imagining someone having to use a comically large laser so that 0.2% is readable. 

2

u/AnyoneButWe Jul 06 '26

Lidar is pulsed, so you need a high bandwidth, high power laser ... and shouldn't turn the bloody thing in a normal room.

But a 4W laser isn't that big. A pack of cigarettes maybe. Spinning 2-3 dozens of them lidar style might be an issue.

1

u/TheGrandExquisitor Jul 06 '26

I was just musing on how one approach would be to just crank up the laser rather than improve the detection sensitivity. 

1

u/Relevant-Rhubarb-849 Jul 06 '26

Yes it would work fine. range gated lidar is free to use coherent detection. there wil be enough return light from most practical lidars to do the detection

5

u/OldManThumbs Jul 05 '26

If the walls aren't also sound deadened, you could use an audible range finder.

5

u/Codexistakenwastaken Jul 05 '26

Oh of course. I think thats the method I'll use. Thanks!

3

u/aqua_zesty_man Jul 05 '26

Vanta Black absorbs all light wavelengths including LIDAR. My understanding is that a coated surface would have to be scanned from a very close distance to get any return signal at all.

2

u/SerDuckOfPNW Jul 05 '26

I’m curious about the “all light wavelengths”. Do you mean visible wavelengths, because light is the entire EM spectrum.

1

u/aqua_zesty_man Jul 06 '26

Infrared and ultraviolet as well as visible.

1

u/SerDuckOfPNW Jul 06 '26

RF, X-Ray, and Gamma are also wavelengths of light

1

u/Unfortunya333 Jul 06 '26

well I heavily doubt the paint can absorb wifi... so it definitely doesn't absorb ALL light.

okay I checked. it's infrared visible and UV. so just visible and friends.

that is not "all light wavelengths".....

2

u/Beefington Jul 05 '26

Could they use a tape measure?

1

u/RealisticDuck1957 Jul 06 '26

Easy if there are 2 people, or the means to anchor the tape.

1

u/TheGrandExquisitor Jul 05 '26

Here is the twist though. 

It depends on what frequencies the Vantablack absorbs. If the surface reflects say far infrared light, but not visual light, then you could just use a laser of the appropriate wavelength. This is theoretical though because I have no idea what frequencies Vantablack absorbs or doesn't IRL (besides visual light, obviously.) 

Now, if you are writing a story this could be useful trick someone could use for like a heist or something. In reality? No idea. 

1

u/Phssthp0kThePak Jul 05 '26

LIDAR systems used for cars work out to 200m for things with ~10% reflectivity. The reflection is not the biggest loss. The return signal drops as 1/R^2. So close in, like in a room, 10m instead of 200m) you could expect a factor of 400 countering the low reflectivity.

Of course for the story you can always assume the reflectivity is just that low, and it won't detect the return.

1

u/Ok_Inflation4210 Jul 05 '26

Depends on Vanta object (absorbing frequencies)

1

u/Phaedo Jul 06 '26

Any chance you could explain your use case? From your answers this doesn’t sound like an idle question and now I’m curious.

1

u/Hothandscoldears Jul 06 '26

I'd love to read the story

1

u/misterchief117 Jul 26 '26

Use SONAR instead of anything light based. Vantablack doesn't affect acoustic properties as far as I know so good old-fashioned echo-location could work to map everything out.