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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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peterloron

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Hello @RedCowboy . Thanks for the information you provided above. I'm in a similar position. I have a high power IR diode which is coupled to a 105um fiber. The end connected to the diode body does not appear to be removable. The other end is bare fiber. I need to terminate it, probably with SMA. Can you recommend any specific terminator kits or parts for this? The ones I've been finding have all been for larger diameter fiber.
 

RedCowboy

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Don't be afraid to just start searching, here's a site and here's another.
I have not bought from these yet, I can usually find something on ebay but I did not see a SMA for 105um just now.

Thorlabs and and the other big name.........minds gone blank....Edmunds will have it but the price will be high, do some searching and you can find a bargain.
 
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peterloron

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Thanks for the quick reply. I've done some digging on ebay, Thor, Newport, Mouser, etc. I've yet to find any SMA connectors for 105um. I'd be happy to swap the existing fiber out for something pre-terminated, but I don't think I can. Here's a pic of the laser.

64244
 

RedCowboy

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You go by the cladding dia. when buying your connector.
I remember mine was 105um fiber as well but my cladding was either 124 or 127 so I used a 127um connector, that's the bore dia. through the ceramic ferrule.
Note: You do strip the end down to the bare glass core and use epoxy to seal it in.


Here you see they say bore size for cladding between 125 and 1580um > https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=1383

See the source image
 
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lasersbee

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Great Optical Fiber info Red...
That's what I did with my FAP Laser.
Rather than investing in equipment to polish
a defective optical fiber for one time... I just
got another one.

Jerry
 
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RedCowboy

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Yes I also have some FAP units with the threaded output which is handy, but my fiber coupled modules like the OP's don't have a threaded connector so there's no choice that I'm aware of but to terminate and polish.
 
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peterloron

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You go by the cladding dia. when buying your connector.
I remember mine was 105um fiber as well but my cladding was either 124 or 127 so I used a 127um connector, that's the bore dia. through the ceramic ferrule.
Note: You do strip the end down to the bare glass core and use epoxy to seal it in.


Here you see they say bore size for cladding between 125 and 1580um > https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=1383

See the source image
Ah! Ok, that makes it more clear. Thanks!
 




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