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Surface finish on SUS304 to prevent laser reflection 1
- Thread starter Finglas
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How strong a laser?
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- #3
Finglas,
You don't prevent laser reflection. You attenuate laser reflection. What we did on one occasion was to stack a set of razor blades in front of the laser, sharp edges facing the beam .
I had a scientist who was in a blind, screaming panic for a laser alignment mirror. I reasoned that a carefully machined stainless steel face would be adequately reflective. It was.
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JHG
You don't prevent laser reflection. You attenuate laser reflection. What we did on one occasion was to stack a set of razor blades in front of the laser, sharp edges facing the beam .
I had a scientist who was in a blind, screaming panic for a laser alignment mirror. I reasoned that a carefully machined stainless steel face would be adequately reflective. It was.
--
JHG
EngineerTex
Mechanical
What wavelength? Black stovepipe paint would work for a lot of wavelengths. When you say prevent reflection, I presume that you are talking about improve absorption.
Also, what temperature? In laser welding, most all of the stainless steel powder/wire used in overlay welding is extremely absorptive at around 3,000F.
Engineering is not the science behind building. It is the science behind not building.
Also, what temperature? In laser welding, most all of the stainless steel powder/wire used in overlay welding is extremely absorptive at around 3,000F.
Engineering is not the science behind building. It is the science behind not building.
EdStainless
Materials
I have also seen the surface pickled to slightly roughen it and then chemically treated to darken the surface for reduced reflection.
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P.E. Metallurgy, Plymouth Tube
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P.E. Metallurgy, Plymouth Tube
- Thread starter
- #8
Finglas,
I remember working on a glass transmitter alignment mirror with 99% reflective face and a frosted back surface. The 1% energy emerging from the frosted surface was dangerous.
Google laser beam dumps. The job is not trivial.
--
JHG
I remember working on a glass transmitter alignment mirror with 99% reflective face and a frosted back surface. The 1% energy emerging from the frosted surface was dangerous.
Google laser beam dumps. The job is not trivial.
--
JHG
My initial though was carbon nanotube coating, which I know nothing about! Here is a quick search that indicates the crazy idea may work:
Search: carbon nanotubes light reflection
Carbon Nanotubes to Reduce Light Scattering in Space Telescopes [720p]
A blacker than black coating could offer minimal laser reflection.
Walt
Search: carbon nanotubes light reflection
Carbon Nanotubes to Reduce Light Scattering in Space Telescopes [720p]
A blacker than black coating could offer minimal laser reflection.
Walt
Compositepro
Chemical
50 years ago if a scientist needed a highly absorptive surface, a candle was used to apply soot. If it needed to resist being rubbed-off then a binder was added to carbon black (soot) to make flat black paint. However, a high powered laser would burn the carbon off, so the beam needs to be spread or scattered to allow absorption. This is where a black-body cavity would be used.
Velvet Flock, Adhesive Backed?
While Vanta Black is indeed absurdly black, it's also absurdly expensive, and not particularly durable as a coating goes. It'll work great in lab environment on a blackbody or for a beam dump in an energy meter.
You could consider a cavity surface made of elongated pyramidal pits with something like a 3:1 to 5:1 aspect ratio, painted black. The cavity will cause reflections to go further into the cavity. A ture cavity blackbody can achieve better than 99.99% absorption. The edge areas that still exist to be perpendicular to the impinging beam will need to be less than 1% of the open area of the cavities.
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You could consider a cavity surface made of elongated pyramidal pits with something like a 3:1 to 5:1 aspect ratio, painted black. The cavity will cause reflections to go further into the cavity. A ture cavity blackbody can achieve better than 99.99% absorption. The edge areas that still exist to be perpendicular to the impinging beam will need to be less than 1% of the open area of the cavities.
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The Vanta Black spray is pretty black, but not as black as the in-situe grown Vanta Black
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EdStainless
Materials
And what about thermal management?
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P.E. Metallurgy, Plymouth Tube
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P.E. Metallurgy, Plymouth Tube
The Vanta Black nanotubes have excellent thermal conductivity
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BrianPetersen
Mechanical
Original poster hasn't given enough information to assess ANY of this.
A 30 watt laser marker may be a Class 4 laser but it's not even remotely capable of doing the damage that a 5 kW welding laser can. The latter will cut through just about anything that its beam happens to be focused on.
The laser radiation from a CO2 laser is far infrared, and the reflected laser radiation won't do much, and it's incapable of going through a lot of materials that are transparent to visible light ... glass, Lexan, and the optics of your eye have low transmissivity to that (long) wavelength. The laser radiation from a YAG laser is near infrared, and it will go right through most materials that are transparent to visible light, including the optics of your eye, which will focus the reflected laser radiation inside your eye just as they do to visible light ... very bad, if it is a high powered laser.
A 30 watt laser marker may be a Class 4 laser but it's not even remotely capable of doing the damage that a 5 kW welding laser can. The latter will cut through just about anything that its beam happens to be focused on.
The laser radiation from a CO2 laser is far infrared, and the reflected laser radiation won't do much, and it's incapable of going through a lot of materials that are transparent to visible light ... glass, Lexan, and the optics of your eye have low transmissivity to that (long) wavelength. The laser radiation from a YAG laser is near infrared, and it will go right through most materials that are transparent to visible light, including the optics of your eye, which will focus the reflected laser radiation inside your eye just as they do to visible light ... very bad, if it is a high powered laser.
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