Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers

LPF Donation via Stripe | LPF Donation - Other Methods

Links below open in new window

ArcticMyst Security by Avery

DIY Carbon foam

Joined
Jan 13, 2010
Messages
2,516
Points
63
Hi everyone. I just seen this in my subscription box and thought maybe some members can find some cool uses for this stuff.

I immediately thought it would make a great beam stop for continuous lasers but, probably not great for high powered pulsed lasers like ruby or yag. Still better than nothing I guess, even if its only one time use.

If you guys do anything creative, be sure to share!


Skip to 3:44 for actual tutorial.
 
Last edited:





CurtisOliver

0
LPF Site Supporter
Joined
Jun 12, 2015
Messages
7,583
Points
113
Nice post Jeffrey. Seems like cool stuff. What would be amazing is if we could get visible light absorbing aerogel for beam stops.
 

Benm

0
Joined
Aug 16, 2007
Messages
7,896
Points
113
Why would this be a good beam stop?

It's interesting stuff for sure, but you might just as well paint a brick black and be done with it. You don't want thermal insulation from a beamstop, and i think you could actually burn a whole through this material over time as it doesnt conduct the heat, so has to either radiate it off or evaporate.
 
Joined
Jan 13, 2010
Messages
2,516
Points
63
I suppose the ol'e brick always works and is probably way cheaper and convenient. I just thought a more DIY solution would be fun. I didn't really give heat dissipation a thought. I guess you wouldn't want to heat up the carbon to something like 1000 degrees or it would just burn/melt/heat everything around it. I just imagined this as a fun hack for us laser hobbiests. "Hey, that beamstop over there is actually just burnt bread".
 

Gabe

0
Joined
Jan 10, 2015
Messages
1,147
Points
83
So happy to see AvE pop up, he's my favourite YouTube channel by far. This could be great for people who do a lot of casting and go through crucibles like crazy and don't want to buy a bunch of graphite crucibles. I can't thing of much use for it in the laser hobby, pretty much all of what we use stays as far away from insulators as possible :)
 

Benm

0
Joined
Aug 16, 2007
Messages
7,896
Points
113
It could be fun to do experiments with though.

I reckon it's one of these things that will dissipate up to some power level for a very long time, but once you go over that level it cannot take the heat away and will start to burn and a whole will be poked through.

Also commeting 'that beamstop is toast!' after succesfully aligning a laser etc would be quite funny :D
 

Gabe

0
Joined
Jan 10, 2015
Messages
1,147
Points
83
It could be fun to do experiments with though.

I reckon it's one of these things that will dissipate up to some power level for a very long time, but once you go over that level it cannot take the heat away and will start to burn and a whole will be poked through.

Also commeting 'that beamstop is toast!' after succesfully aligning a laser etc would be quite funny :D

Yeah like he showed its not conductive in the thermal or electrical sense, so it wouldn't really dissipate the heat just absorb it, and since it's carbon its melting point is really high. lol I like that, because it's so literally true.
 
Joined
Sep 12, 2007
Messages
9,399
Points
113
This could be great for people who do a lot of casting... and don't want to buy a bunch of graphite crucibles.

They're like $10 on ebay. The fuel, equipment, and time to construct one out of bread is well over $10, and will yield a vastly inferior product. How are you going to form bread into a leak-free cylinder to begin with?
 

Gabe

0
Joined
Jan 10, 2015
Messages
1,147
Points
83
They're like $10 on ebay. The fuel, equipment, and time to construct one out of bread is well over $10, and will yield a vastly inferior product. How are you going to form bread into a leak-free cylinder to begin with?

Overestimated the cost of graphite crucibles, my bad. Iunno, maybe pack it into a cup shape in an offcut of tubing. The super-toast didn't seem too misshapen relative to normal bread, I think it might work. Might be tough to get it out without cracking it, though.
 

Benm

0
Joined
Aug 16, 2007
Messages
7,896
Points
113
Yeah like he showed its not conductive in the thermal or electrical sense, so it wouldn't really dissipate the heat just absorb it, and since it's carbon its melting point is really high. lol I like that, because it's so literally true.

I think it would actually just burn in air if heated with enough laser power.

Torches and such cannot heat something to a temperature above their own, but lasers easily can, and there is no real limit to how high that can go given enough power.

Also, something like an oxyacetylene torch is not the best thing to burn materials: the reaction that powers the torch uses up a lot of oxygen leaving very little to combust whatever you are trying to set on fire. This can be remedied to some degree by running the torch lean, but with laser heating the full 21% oxygen from the air would be available.
 

Gabe

0
Joined
Jan 10, 2015
Messages
1,147
Points
83
I think it would actually just burn in air if heated with enough laser power.

Torches and such cannot heat something to a temperature above their own, but lasers easily can, and there is no real limit to how high that can go given enough power.

Also, something like an oxyacetylene torch is not the best thing to burn materials: the reaction that powers the torch uses up a lot of oxygen leaving very little to combust whatever you are trying to set on fire. This can be remedied to some degree by running the torch lean, but with laser heating the full 21% oxygen from the air would be available.

That's very well possible. How much power do you reckon? High CO2 laser range?
 
Joined
Sep 12, 2007
Messages
9,399
Points
113
No, this wouldn't work as a beam stop for anything class 4. The insulative properties mean the material that meets the beam would get hot enough to burn away because so little of the heat is transferred away. The irradiated spot would turn to (white) ash over the course of a few seconds or a few minutes.
 




Top