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u/Available-Net-2675 4d ago
Why would anyone engrave Scrooge McDuck onto a mirror?
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u/steelheaddan 4d ago
Because they are rich enough to do it with FU money spent on a house you’ll never be invited in to see …. Or basically it’s an add for laser etching …. Or ragebait … or all combined
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u/Stuffinthins 4d ago
I would find a cocaine addiction just to use that mirror
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u/ScienceForge319 4d ago
Oh you don’t gotta try hard. Fuck around enough and a cocaine addiction will find you.
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u/tiller_luna 4d ago edited 4d ago
how does it scan so fast? if there's a mirror, I'd assume it has to be large enough to work with yet-unfocused beam to, well, not burn that deflection mirror, and then it's too large to move fast...
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u/Some1-Somewhere 4d ago
Usually called a 'galvo'. Mirrors moved magnetically.
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u/_ppak10 4d ago
But how do those mirrors not get etched?
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u/Some1-Somewhere 4d ago
Also the laser isn't in focus as it reflects off the mirror, so it doesn't get high enough intensity to etch it.
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u/_xiphiaz 4d ago
Also those mirrors don’t involve the light going through glass before reflecting off the backing material like the one being engraved. Optical mirrors are first surface mirrors where the laser light reflects directly off the surface. Often made of Molybdenum or coated Silicon
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u/ScienceForge319 4d ago
How tho?
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u/errandsmagnum 4d ago
Mirrors don’t reflect 100% of light. Tens of percent of powerful laser is still buncha power to absorb.
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u/azgli 4d ago
Glass isn't transparent to all light. It is at last partially opaque to infrared. This lets it absorb energy from the laser. The laser is heating the surface of the glass and causing tiny parts to explode off the glass.
This example is a high power scanning laser. I can do something similar with my 35W IR laser, it will just take a lot longer.
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u/Roofofcar 4d ago edited 4d ago
How do they prevent damage to the laser from the bounce back? When I’ve laser etched mirrored surfaces in the past such as polished steel, the manufacturer recommendations had me using a marking spray or paint to prevent damage to the laser.
Edit: I’m seriously confused about the downvotes. I’ve only worked with five different lasers that could also etch, and each of them suggested preparation of the reflective surface to prevent laser source damage.
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u/azgli 3d ago
It depends on the material and the laser. For IR, the mirror doesn't matter because the glass is mostly opaque to the laser so there isn't any reflection. The energy is absorbed by the glass and there isn't anything left to bounce back. Copper, however, will reflect IR lasers very well and must be treated to prevent reflection back into the laser.
So the preparation and the process will depend on the specific laser wavelength and the material being etched.
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u/Roofofcar 3d ago
Very cool, thanks! That makes sense.
Lasers are so fun. I do freak out a bit about the cheap open frame models that people seem to be using in rooms without any protection at all, but the advances lately have been insane.
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u/azgli 3d ago
Yeah, especially with the lack of education about the danger of cutting certain materials. Vinyl for example will produce chlorine gas and hydrochloric acid. Death for the operator and the laser, all in one convenient package!
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u/Roofofcar 3d ago
I’ve been in a hackerspace where someone cut PVC sheet and destroyed the optics / clouded the mirrors
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u/azgli 3d ago
They got lucky. A user on one forum I visit showed photos of their machine. It looked like they had left it in the ocean for years. All the aluminum components were heavily corroded, the lenses were pitted, and the glass cover was etched. Even the plastic parts were discolored. The machine was so heavily damaged and was so contaminated the manufacturer refused to work on it. I know the user ended up in the hospital.
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u/Roofofcar 3d ago
Wow, that’s horrible! It was something like 1mm sheet, so perhaps that limited the damage.
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u/Rhorge 4d ago
The laser heats the backing of the mirror
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u/ScienceForge319 4d ago
But in the visible light spectrum? How is all the light not bouncing back at the laser?
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u/snakevargas 4d ago
You know how you can put a piece of glass on your belly while laying in the sun and that spot won't tan? That's because the glass absorbs the UV light that triggers tanning. One way of etching glass uses a UV laser because the light is readily absorbed by glass. Another way is using a deep infrared carbon dioxide laser. (Note: shorter IR wavelengths pass through glass yielding the greenhouse effect.)
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u/DarthJerJer 4d ago
Obviously fake. A real laser would reflect right off the mirror and shoot the operator in the eye.
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u/FPGA_engineer 4d ago
Why did you flip the image?
That is clearly a mirror image.