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Repolish laser fiber

MrMcChicken

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Hey folks, lately i scored a 50W SMA fiber coupled laser on ebay the other day.
The fiber is perfect on the one side, but smashed on the other, so i have to polish it.
I have seen Marco Reps on youtube doing this, but he had a bare fiber end.
My fiber is surrounded by a stainless steel surrounding. Do I have to cut it off,
in order to have the bare fiber? Or can I just polish the whole end including the metal part?

Cheers
 

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steve001

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Hey folks, lately i scored a 50W SMA fiber coupled laser on ebay the other day.
The fiber is perfect on the one side, but smashed on the other, so i have to polish it.
I have seen Marco Reps on youtube doing this, but he had a bare fiber end.
My fiber is surrounded by a stainless steel surrounding. Do I have to cut it off,
in order to have the bare fiber? Or can I just polish the whole end including the metal part?

Cheers
While waiting for a reply, keyword search using your preferred browser I suggest Google. "how to polish optical fiber with cladding" You'll probably have an answer faster than waiting for a reply.
 

RedCowboy

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You have to get down to the bare glass and there's a clear coating that you have to strip as well then you can do a rough polish but you will want to terminate the end and polish with a puck and polishing paper against a very flat hard surface such as a mirror.




This looks like bare fiber but it's not, there is still a coating that will burn when the laser is powered up.


Here it is after the coating has burned back some, but you want to strip it off then hand polish, terminate and finish polish.


In your pic you still have the coating on the glass, you need to strip it off then polish the glass fiber without the coating or it will foul the surface, the polished face of your fiber is an optical component and needs to be clear. I can see a problem in the center, also you need to strip off the coating.

sad_fiber.jpg


I have used this, first use the fine then the extra fine, polish in a figure 8 motion keeping the puck flat with light pressure, you will need to get a termination and the puck separately, what fiber coupled module do you have, look it up and find the dia. of your fiber then search ebay for a termination and polishing puck.

--edit-- Ok I see you said SMA so find a SMA terminal, if you want to you can hand polish your fiber but you have to strip it down to the bare glass and use the diamond film paper.

Once you have a SMA termination glued in and polished you can look for a collimation lens, something liket this > https://www.ebay.com/itm/Thorlabs-F220SMA-B-633-nm-f-10-99-mm-NA-0-25-SMA905-Fiber-Collimation-NEW/283260632518?epid=1134239661&hash=item41f3a63dc6:g:rb4AAOSwcWJb7IEs


 
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MrMcChicken

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Hello again, thanks for the information! It seems to be a more common problem than i have thought of.
I have just removed the broken part. The fiber is 600µm. I'll get the polishing stuff and keep you updated.

Thanks!
 

RedCowboy

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Do you have a SMA termination at your laser module such as the FAP module ?
If so you can buy a new cable with terminals to attach to an optic.
Otherwise you will need a termination and you want to strip your fiber down to bare glass then cleave it to length so you can fit it into the termination and then you will mix epoxy and glue the fiber into the termination, once cured you cleave at the end of your termination and polish the fiber end in the termination with a puck and ultra fine paper, if your kit has 3 micron and 0.5 micron then use the 3 micron 1st then the 0.5

I bought this and it works just fine, just stroke across your fiber then hold on each side of your score line and give a tug, the fiber will separate. If you try to cut with wire cutters your fiber is likely to shatter leaving a very rough end that won't polish.



---EDIT---
Reading your original post again I see you say one end is smashed........you will want to cut strip back past all the damage or if your fiber has a connector at the module end consider buying a new jumper with terminations already installed and ready to use.

Will you be using this laser for a cutting table or just experimental.....pumping by any chance ? Do you have a lens picked out ? I'm sure you have laser safety glasses and if not get some before powering it up, also you will need a power supply/driver and you have to keep the laser module cool.

You can use a security camera to view the beam and spot or remove the IR filter from a cheap camera, but I expect you know that you must protect your eyes, this is the most important part by far.
 
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