4 ms·

I get laser safety curtains, but what do you do for reflections off the ceiling? Asking because our makerspace was recently donated a fiber laser welding unit a

I get laser safety curtains, but what do you do for reflections off the ceiling? Asking because our makerspace was recently donated a fiber laser welding unit and we don’t yet know best practices for not blinding our membership short of building a completely enclosed separate room for it with door interlocks.

fasa99 2y ago
What I do to match my lazer curtains is I hang a lazer tapestry off the ceiling to block all the lazers. I don't do lazer welding but I have lazer scissors and lazer axe which it is still useful for
DannyBee 2y ago
Ideally you have an enclosed area with interlocks. All of the laser welders support it (and it's the standard way). They make and sell mobile ones that can be pushed around. See, e.g., https://lasersafety.com/barriers/rigid-barriers/ https://lasersafety.com/barriers/rigid-barriers/ for some examples (I don't know these folks, they just have helpful pictures/listings of kinds of things that exist) If you can't do this, you do need to panel or curtain the ceiling or use laser absorption coating or other things. There are places that also just use reflection sensors that detect reflection on the ceiling and trigger (again, machines already support handling this). I have heard this works very well but have no direct experience with it. All that said, reflection off ceiling is more uncommon for practical reasons (The angle at which you hold the gun to the piece, the fact that ceiling directed angles often become back reflection into the gun which it already detects, etc). They already detect very high reflection as well. For a makerspace, one of the issues you will have is that people will likely want to try to weld copper and aluminum a lot, both of which are highly IR reflective. If you said "You can only weld steel and iron" you would eliminate a very high percent of reflection in the first place. Here's a basic chart that looks right: https://www.researchgate.net/profile/Tomasz-Kurzynowski/publication/234118523/figure/fig2/AS:300043786571777@1448547421302/The-absorption-of-laser-output-at-different-wavelengths-varies-according-to-the-materials.png https://www.researchgate.net/profile/Tomasz-Kurzynowski/publ... For a 1064nm laser, you can see Al or Cu is going to reflect a lot of the energy, while steel/iron are still off the graph high in absorption
- convolvatron 2y ago
  I tig. wear a helmet and have to buy argon every year. this seems like a huge hassle in comparison. is there that big a difference in quality and or range of processes that make it worth it?
  - abakker 2y ago
    its the operator skill part when dealing with thin sheet metal. It just works better / easier / faster for thin stuff, where in TIG, that's the high-skill work that everyone pays big bucks for. Agree with the post above, though. The safety setup for lasers is basically full isolation.
    - convolvatron 2y ago
      seems like its more cost effective to just stay on or above 20ga unless you're really high volume or you really need the weight savings
  - hinkley 2y ago
    I know one of the reasons we wanted pico-second and shorter pulsed lasers is that they can cut material with little to no damage of the neighboring material. There was a demo that I read about when this was all brand spanking new research, where they claimed that a laser scalpel causes no heat damage to tissue outside of a cell’s breadth from the contact point.
    - cyberax 2y ago
      That's how LASIC and PRK work, after all!
    - justinclift 2y ago
      Is it this? https://en.wikipedia.org/wiki/Coulomb_explosion https://en.wikipedia.org/wiki/Coulomb_explosion
      - 2y ago
bozhark 2y ago
Separate room with interlocking doors -coming from another hacker space
dheera 2y ago
> completely enclosed separate room for it with door interlocks You absolutely, absolutely need this. Do not take chances. "Real estate is expensive" is not an excuse for a blinding hazard to members and visitors of your space. I've worked with very high powered room-sized laser cutters before and they should all have a full room enclosure.
cowthulhu 2y ago
Are lasers typically able to reflect off of surfaces that diffuse light (ie drywall)? I’m totally ignorant when it comes to laser safety, apologies if this is a stupid question .
- meindnoch 2y ago
  Do you see a bright spot when aiming the laser at drywall? If the answer is yes, then laser light is being reflected into your eye. Hope this helps!
  - jtwaleson 2y ago
    I’m confused. This is true from every angle from which you look at the wall right? So there has to be quadratically less reflection than e.g. a mirror, but still a lot more then a completely black surface.
    - meindnoch 2y ago
      The inverse squared falloff from a diffuse surface is not enough to prevent eye damage if you're in a regular-sized room, and playing with a class IV laser, or even some class IIIb lasers (depending on the distance, and the duration).
      - jtwaleson 2y ago
        Got it, thanks!
  - Dylan16807 2y ago
    It's not that simple. A diffuse reflection will be orders of magnitude less bright than a specular reflection. For a very wide range of laser powers (not 2.5kW), the trouble is in guaranteeing a diffuse reflection.
  - jrockway 2y ago
    > Do you see a bright spot when aiming the laser at drywall? It was red for a second but now what appears to be a black hole is consuming everything.
llm_trw 2y ago
>we don’t yet know best practices for not blinding our membership short of building a completely enclosed separate room for it with door interlocks. That is the only way to not blind your membership.

fasa99 2y ago

What I do to match my lazer curtains is I hang a lazer tapestry off the ceiling to block all the lazers. I don't do lazer welding but I have lazer scissors and lazer axe which it is still useful for

DannyBee 2y ago

Ideally you have an enclosed area with interlocks. All of the laser welders support it (and it's the standard way). They make and sell mobile ones that can be pushed around. See, e.g., https://lasersafety.com/barriers/rigid-barriers/ https://lasersafety.com/barriers/rigid-barriers/ for some examples (I don't know these folks, they just have helpful pictures/listings of kinds of things that exist) If you can't do this, you do need to panel or curtain the ceiling or use laser absorption coating or other things. There are places that also just use reflection sensors that detect reflection on the ceiling and trigger (again, machines already support handling this). I have heard this works very well but have no direct experience with it. All that said, reflection off ceiling is more uncommon for practical reasons (The angle at which you hold the gun to the piece, the fact that ceiling directed angles often become back reflection into the gun which it already detects, etc). They already detect very high reflection as well. For a makerspace, one of the issues you will have is that people will likely want to try to weld copper and aluminum a lot, both of which are highly IR reflective. If you said "You can only weld steel and iron" you would eliminate a very high percent of reflection in the first place. Here's a basic chart that looks right: https://www.researchgate.net/profile/Tomasz-Kurzynowski/publication/234118523/figure/fig2/AS:300043786571777@1448547421302/The-absorption-of-laser-output-at-different-wavelengths-varies-according-to-the-materials.png https://www.researchgate.net/profile/Tomasz-Kurzynowski/publ... For a 1064nm laser, you can see Al or Cu is going to reflect a lot of the energy, while steel/iron are still off the graph high in absorption

convolvatron 2y ago
I tig. wear a helmet and have to buy argon every year. this seems like a huge hassle in comparison. is there that big a difference in quality and or range of processes that make it worth it?
- abakker 2y ago
  its the operator skill part when dealing with thin sheet metal. It just works better / easier / faster for thin stuff, where in TIG, that's the high-skill work that everyone pays big bucks for. Agree with the post above, though. The safety setup for lasers is basically full isolation.
  - convolvatron 2y ago
    seems like its more cost effective to just stay on or above 20ga unless you're really high volume or you really need the weight savings
- hinkley 2y ago
  I know one of the reasons we wanted pico-second and shorter pulsed lasers is that they can cut material with little to no damage of the neighboring material. There was a demo that I read about when this was all brand spanking new research, where they claimed that a laser scalpel causes no heat damage to tissue outside of a cell’s breadth from the contact point.
  - cyberax 2y ago
    That's how LASIC and PRK work, after all!
  - justinclift 2y ago
    Is it this? https://en.wikipedia.org/wiki/Coulomb_explosion https://en.wikipedia.org/wiki/Coulomb_explosion
    - 2y ago

bozhark 2y ago

Separate room with interlocking doors -coming from another hacker space

dheera 2y ago

> completely enclosed separate room for it with door interlocks You absolutely, absolutely need this. Do not take chances. "Real estate is expensive" is not an excuse for a blinding hazard to members and visitors of your space. I've worked with very high powered room-sized laser cutters before and they should all have a full room enclosure.

cowthulhu 2y ago

Are lasers typically able to reflect off of surfaces that diffuse light (ie drywall)? I’m totally ignorant when it comes to laser safety, apologies if this is a stupid question .

meindnoch 2y ago
Do you see a bright spot when aiming the laser at drywall? If the answer is yes, then laser light is being reflected into your eye. Hope this helps!
- jtwaleson 2y ago
  I’m confused. This is true from every angle from which you look at the wall right? So there has to be quadratically less reflection than e.g. a mirror, but still a lot more then a completely black surface.
  - meindnoch 2y ago
    The inverse squared falloff from a diffuse surface is not enough to prevent eye damage if you're in a regular-sized room, and playing with a class IV laser, or even some class IIIb lasers (depending on the distance, and the duration).
    - jtwaleson 2y ago
      Got it, thanks!
- Dylan16807 2y ago
  It's not that simple. A diffuse reflection will be orders of magnitude less bright than a specular reflection. For a very wide range of laser powers (not 2.5kW), the trouble is in guaranteeing a diffuse reflection.
- jrockway 2y ago
  > Do you see a bright spot when aiming the laser at drywall? It was red for a second but now what appears to be a black hole is consuming everything.

llm_trw 2y ago

>we don’t yet know best practices for not blinding our membership short of building a completely enclosed separate room for it with door interlocks. That is the only way to not blind your membership.