Fiber Optic Cable + Lasers ... Questions...

[badinstincts]

1. I was wondering where can we buy those fiber optic cables/strands?
I want to get like a 10 foot cable, cut it up and play around with. Looks like a lot of fun.

2. Also does anyone know if you lose a lot of power from running the laser through the cable?

3. Will the laser still come out a beam or not?

4. Does it matter if you use green, red, violet lasers?

5. And is there a coupler which merges 2 or more beams?
That would be awesome too.

 

[o_DEATH_ANG3L_o]

I don't think that it will come out as a beam on the other end. Only because the cable would refract the light a little. But might wanna get someone else's opinion as well.

 

[FrothyChimp]

You might try Graybar Electric since they have warehouses in most major cities. You can get pigtailed single and multimode fiber from them or buy components and build your own. The only drawback is that you also have to buy the cutting and polishing equipment and practice, practice, practice to do a decent terminating job. You also need to keep in mind that you somehow need to couple the fiber to the output of your laser with minimal loss which means you need to collimate the beam down to a strand of fiber size. Depending on what you want to do with it you may also have to consider the waveguide properties of the fiber for your particular wavelength, etc.

 

[danielbriggs]

I was going to post my findings in my Hex Burner Post, as someone suggested that, but anyway:

Using high quality fiber optic cables that are used in data transmission, I can say that you can't see the beam, this is mainly due to the fact that it's hard to get most of a 1.5mm beam down a 0.02mm fiber. I tried loads of different optical connectors, and I just got nothing! I tried loads of different focal points, moving it around etc, and still no joy. Even if you use a dedicated fiber laser (which I borrowed off my Dad), again due to the diameter, you only get a tiny tiny dot, which is useless!

BUT: I recon, if you get the "fibre optics" that you can find in those kids glow wand things, you might be in luck, as they are about >1mm diameter.


Dan

 

[tatman]

i took a laser printer (HP) apart once to get the "laser" part out and found a powerfull infra-red laser diode inside. what't interesting is that i also recovered a 6 to 8 inch piece of fiber optic cable that seemed to "couple"the ir to something. it had a small piece on one enc that held a small lens.

 

[likewhat]

As someone above mentioned, launching a laser into a fiber is nontrivial. Fibers that are used for transporting lasers might have a core diameter of 10 microns, so you have to focus the beam to 10 microns and be able to have micron precision in aligning it.

Not all fibers are that small though. If you get one with a huge core size (100s of microns) you can just point the laser at the end of it and a lot of it will couple into the fiber. To get all of the beam into the fiber you need to focus it down to a small spot right on the end of the fiber. You will lose very little signal when it is actually traveling in the fiber.

When it comes out it will behave identically to a beam that was focused to a spot size equal to the fiber core diameter. So it will be diverging as such. If you put a lens after it with a small focal length you can catch the beam and collimate it.

If you just get a piece of bulk fiber you will need to make a decent holder for it so that it can be positioned in a stable manner. You can cut bulk fiber with a razor blade that you hit with something. Then you can polish the end of the fiber with some 2000 grit sand paper lubricated with water or alcohol. If you dont polish it you will see many rings on the output. If it is polished the diverging output beam will appear fairly gaussian.

 

[badinstincts]

hmm, seems like its not as easy as i thought. i figured fiber optic cable would be similar to the kid wand toys, but i guess i was wrong. but dont they use fiber optic cable in those medical probes and stuff, spy equipment, shouldn't it be thick enought...

 

[pseudonomen137]

In a probe, there will still be lenses on each side - its not a nice tube you can look into and see somewhere else, unless you buy one huge cable. For those applications though, you're not worrying about keeping your nice perfect laser beam intact. Just mass transporting a jumble of light.

For a laser, in order to keep good beam specs you need to use a special, small fiber tailored for the application. Otherwise you lose coherence and the beam specs get messed up. Also, as said above, in order to transport a laser beam through a cable, and have it exit as a beam, you need to focus the beam into the fiber, and re-collimate it out of the fiber. You can't just shoot a beam straight in and get a beam out the other end.

 

[danielbriggs]

Just get some Acrylic Rod, about 3-5mm and that will do you!
http://stores.ebay.co.uk/Clear-Plas..._W0QQcolZ4QQdirZ1QQfsubZ2493217QQftidZ2QQtZkm

It won't be too bendy, but it flexes. You CAN snap it quite easily if you bend a 30cm length more than 40 deg. Think of it more as a light extension with a bit of play in the movement. It works great with LED's, as I've used it in the past. I think it's sometimes referred to as "light gathering rod" so, I'm sure it will work with a laser

One thing: If you do start waving it around, secure the laser input end very well to the laser, as you will alter how much beam enters the rod if the face of the rod is not flush.

This would be a great demo to show how fiber optics work, i.e. showing the TIR (Total Internal Reflection) with laser beam.

 

[zerafiel]

I think they said you can't just use any fiber and expect coherent light coming out even if you do manage to focus it into the fiber. the fiber needs to have the proper waveguide properties.
Heruur was selling some fiber launch lenses a few weeks ago on ebay.