Laserbeam into a fibre

[edison]

Hello Guys.

I did some research on PL to find info about pushing a laserbeam into a fibre and what parts are needed but nothing comes up. Can anyone explain how it works or do a small sketch? I also understand that fibre,s come in different sizes like 50um , 100um , 200um etc but i don,t understand how that relates to losses and beamsize etc

I read that there are different connectors aswell like FC, ST or SMA so lets say i want to buy a fibre wich one do i need to buy in size , what connector and what NA?

Thanks!

[VDX]

... I'm using fibers for 'homogenizing' or to symmetrize the pretty inhomogene beams of diodelasers for material processing.

For me it's essential to put as much power in as thin fiber as possible - 105 microns diameter is good, 50 microns would be better ... but the smaller the entry, the more complex the focussing.

With smaller fiber diameters the refocussed spot is smaller too -- I can focus the output of a 105µ-fiber to around 100 to 150 microns spot diameter in 20 to 40mm distance, what's my normal working mode for engraving ... or for up to 200 microns in 60mm distance for cutting.

This should be similar for beam shaping too - the smaller the fiber core diameter, the better beam parameters (diameter, divergence, beam profile) should be achievable ...

Viktor

[catalanjo]

Hey Victor, do you know anyone here in EU who can put an SMA connector on to the end of a broken 10micron high power Argon delivery fibre. I have a Zeiss eye surgery laser that I have been trying to fix for more than a year now but can't get replacement fibres so this would be my last resort.

Cheers

[NobleGas]

Is the fibre definately 10um? 9um is a more common size, at least for comms fibres.

[VDX]

... 10µ (or 9µ) would be pretty hard to feed the beam into or center the fiber exactly into the middle for reproducible results.

I'm cleaving the 100µ- and thicker fibres and have some equipment too for attaching FSMA connectors and polish the ends.

Have some precise justage equipment (micro- and nano-positioners) and measuring equipment at home -- but some problems too, finding enough time/motivation beside the other projects ...

Viktor

[Draco]

the last time i did it was with a polished fiber from an employer and they had an X/Y adjustable table under a microscope to align the fiber as close to the emitter as possible, on the bar diode i have, it uses an FAC across the emitters with one fiber per emitter, it was a bitch to realign when i loosened the wrong screw, when we did it at that company we had the laser on at reduced power and adjusted to peak before gluing the fiber in place, one time i dosed off for a split second and bumped the scope and broke the fiber, oops, that was tedious work.
on my bar diode i accidentally burned the end of the fiber bundle and my boss was able to polish it, i have not used it since, i don't know what the connector is and i want a focus lends on it to prevent the finder end from damage, it's one of the 20-40 watt bar diodes from spectra physics that pop up on ebay, it has metal encased fiber cable, one day i would like to make an engraver out of it

[catalanjo]

Is the fibre definately 10um? 9um is a more common size, at least for comms fibres.

Sh**t ...thanks for pulling me up on that one..... my typo (or mental lapse) ... it is definitely a high power 50x125 micron fibre NOT 10.
Not a comms fibre at all.
I never had any problems at all launching into that size with an Argon beam! (using a x4 microscope objective)
Just need someone with the right gear to cleave it nicely, fix the SMA connector centred on the end and polish it to minimise losses!

I would willingly pay for this service !

Cheers

[mixedgas]

Cat, I know some one who does that service for laser show users.. PM Sent.

Steve

[VDX]

... it's one of the 20-40 watt bar diodes from spectra physics that pop up on ebay, it has metal encased fiber cable, one day i would like to make an engraver out of it

I have one of this "25Watts-bar-diode" with 19 emitters and 19 fibers, bundled to a single output inserted int a FSMA-connector.

It sounds like a 'strong laser', but with an output diameter of 0.8mm it's only refocussable to maybe 0.7mm and it's not a single spot, but an averaged 19-spot-focus.

I have a 25Watt diode with a single 105µ-fibre (3x 9Watt-emitters combined into the 105µ fiber), what's around 60x the energy density of the 'bundle-fiber-diode'!!

Have some 9Watt-diodes with the same 105µ fibers attached - roughly 10x more energy density than the 25W-bundle!! ... and easy to focus to a 0.1mm spot diameter

Viktor

[NobleGas]

I know someone in the UK who can do the job, let me know if you need his contact details.