Senior Member
fiber optic beam combining
One of the chinese module sellers, Goldenstar, told me that that their higher power modules use optical fibre for beam combining in one of the promotional emails.
Also mentioned on the website: http://goldenstarlaser.com/index.php...product_id=391
"diode with fiber process,with cylindrical mirror"
How does it work and what is the advantage over knife edging? Are the fibers from each diode just arranged in a parallel array or grid before the correction optics?
Senior Member
They attach a fiber as the fastest axis collimination and it makes a stripe, that can be knife edged easy.
Senior Member
Sorry don't think I understand, makes a stripe?
Jr. Woodchuckington Janitor III, Esq.
interesting. i'd like to see the output of that module.Originally Posted by Nii
suppose you're thinkin' about a plate o' shrimp. Suddenly someone'll say, like, plate, or shrimp, or plate o' shrimp out of the blue, no explanation. No point in lookin' for one, either. It's all part of a cosmic unconciousness.
Senior Member
... look here, at the 4th image with the 3 small 9W-lasers in the opened housing of a 25W-IR-diode - http://www.reprap.org/wiki/Laser_Cutter
They used cylinder lenses to 'collimate' the beam to a horizontal line, so they can combine the three lines together on the last focussing lens and into the 105µ-fiber ...
Viktor
Senior Member
This is interesting. A fiber does not collimate. I know you put "" "" around this, but aside from the verbiage, a fiber tends to degrade the output from a diode by randomizing the ray paths within it. The fiber may make the act of knife edging more convenient, but the loss in the fidelity of the ray paths is likely to deteriorate the result. Now, if this is a single mode diode into a single mode fiber then the results should equal (but, not surpass) a free space set up. Coupling a single mode diode into a 10um or less single mode fiber is a significant challenge. Golden star would not do this in house. To build such a low cost, low power projector with these kind of fiber coupled diodes would make me very interested as to the source.They attach a fiber as the fastest axis collimination and it makes a stripe, that can be knife edged easy.
Senior Member
... you can use a short piece of a glass fiber as cylinder lens, if placed across the output -- this can give a "line" by collimating the fast axis, but the slow axis won't change much ... but this could be enough to knife-edge and add/overlay the beams into a fiber inside a small module housing.
IPG did this with two cyl. lenses per diode, as seen in the image I've linked ...
Viktor
Senior Member
Key words here seems to be "across the output".
In which case Mr. P " A fiber DOES collimate ! (albeit just in one plane) ... as it IS a "cylinder"...and in this case arguably a "lens" as well.
Presumably this is about as close to the output of a diode as you can get with a "lens"
Viktor from where did you get fibers with no cladding and what distance from the diode are they placed
Unfortunately it is very difficult to see what is going on from the pic....perhaps a drawing would make it easier to understand.
Cheers
Senior Member
... for short pieces it's no problem to first remove the cladding, then scribe and snap the piece.
If you need some - I've got some rolls and cut pieces of glass fibers from 0.2mm to 2mm diameter from a friend, and have enough of the 105µ fibers used with the pumping diodes and too some cylinder- and GRIN lenses from older projects, so didn't search newer sources.
Can send you some pieces for testing, if you want ...
Viktor
Senior Member
Hey many thanks Viktor, I may well take you up on that offer, so please don't chuck the bits of fibre into the rubbish..... however I am still trying to get my head round the opportunities this technique might present.
Since you seem to be a master of the "understatement", I haven't quite figured how you mount the "short piece" which you "place" across the diode output.
I am guessing that you use glue and just treat 100microns like most of us would deal with a few millimeters.
It has been literally many years, since I last mucked about with fibres, but I will PM you once I have figured out what exactly to do with the "bits & pieces" in relation to Mitsu red concentration.
Cheers
PS. I realise that the distance from fibre "placement" to diode output depends on fibre diameter but as I do not know refractive index of fibres in question, I can't manage to get an idea of the distances and precision involved.
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