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DPSS green messed up...

Markus Unread

Markus Unread

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Jul 27, 2010
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Took out an older 80mw greenie last night and noticed the beam has a lot of diffraction splatter around it. This picture is of the spot and surrounding yuck.
The laser is about 5 ft from the ceiling.
Is this just dirty optics? I'm hoping that's all it is. Although it's going to be a bitch to get to (recessed in a heatsink).

33536_140394629327706_100000715098290_248121_2979192_n.jpg
 





Got it all apart and the IR filter has microscopic cracks in the coating so I just removed it. Not great, but a lot better...
 
I assume you know that IR is going through now. I'm not sure if it would be safe or not. It would depend on how it's collimated relative to the green light and how much is coming out. What laser is this?
 
It's an old lab laser from china (brand?). I tried cutting up a hot mirror from a Nikon camera that I converted to IR, but it was a multilayer laminate so that didn't go well. Someday I'll run into some IR filter glass and take care of it.
 
I think there are folks here who can get you pre cut IR filters rather cheaply. How you'd attach it I don't know, I wouldn't recommend superglue - that fumes pretty badly.
 
NOOO. Yeah, super glue would totally screw up the filter. That stuff leaves nasty cloud like residue. Id use bubble gum before that lol. I don't know what it would be called, but it's like a gel that drys into a semi hard rubber like material. That's something I would use. You could also use it on collimation lens threads to hold it in place as you can remove it.

Though that reminds me. A hot glue gun may also work. It's just getting it in place cleanly would be the hard part. That stuff can really string out like melted cheese lol.
 
aryntha said:
I think there are folks here who can get you pre cut IR filters rather cheaply. How you'd attach it I don't know, I wouldn't recommend superglue - that fumes pretty badly.
Click to expand...

Not only does it fume badly, it also will "develop" any trace of oils from fingers etc.Possibly best adhesive ever made for ruining optical assemblies.
A spring assembly would work perhaps.Then it could be easily changed out if it got scratched etc.
 
really any cyanoacrylate is a bad idea with optics, idk what to use, maybe hotglue or something like that just at a lower temperature.
 
Moptsp said:
NOOO. Yeah, super glue would totally screw up the filter. That stuff leaves nasty cloud like residue. Id use bubble gum before that lol. I don't know what it would be called, but it's like a gel that drys into a semi hard rubber like material. That's something I would use. You could also use it on collimation lens threads to hold it in place as you can remove it.

Though that reminds me. A hot glue gun may also work. It's just getting it in place cleanly would be the hard part. That stuff can really string out like melted cheese lol.
Click to expand...

You mean epoxy?
 
I would use a two-part non-outgassing silicone. It sets in minutes and remains flexible so the filter can expand and contract without deformation or cracking. It's also good to pretty high temps which makes it a plus for high-power stuff.
 
a product called "goop" is nice to optics, a little fumey but the fumes dont normally adhere to things. i would test i before putting on your laser, ive had good luck with it.
 
I thought about Goop and the other acrylic-based adhesives, but they suck at high temp (>160F). Epoxy is better, but rigid. If I can't find the two-part silicone locally, I'll test a couple of one-parters and see how they work.
 
You don't really need an IR filter, it's not going to cause any harm in normal operation. Although your laser will measure higher on power meters, so don't get too excited when you see a jump in power :p
 
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