I've recently found a good supplier of FO cable in the UK; Blue Helix - http://www.bluehelix.co.uk/ The grade is GH4001 (Eska Premier) , a polyethylene jacketed, 1mm single core, 2.2mm O.D.
My question is: what is the best way of creating a coil in FO cable? Of course the cable needs to be wound around an appropriate mandrel but is wet heat (boiling water) or dry heat (hot air paint stripper gun) best for the job?
Thanks, Tim
Wet heat is faster and more convenient... you can boil a couple eggs&sausages at the same time!
Thanks David
I have had better luck with the dry heat (the sausages notwithstanding) but I have access to an annealing oven that can control temp quite well. If you do it in water I get best results starting in cold water then heating it up slowly to 95C or so then cooling slowly rather than dip and dunk in already boiling water. Make your mandrel about half the size that you want the ultimate coil to be.Bill
Great advice, thanks Bill
Do you people really boil sausages?
Do you people really boil sausages?
You know, spaniards are famous for our inventive cuisine!
Well in New York they sort of boil hot dogs and hot dogs are sort of sausages. A good "dirty water" dog is a treat that you can't get in Los Angeles.
Bill
Happy Thanksgiving.
Dirty water dog.... sounds nice!
Make your mandrel about half the size that you want the ultimate coil to be.Bill
What's the diameter you can achieve? Is it about the same as for example the Sea & Sea cables, or is it larger?
I have never gotten one quite as small as the S&S ones, but I don't have a winder that can put the coil down with the right diameter. I wind it around a pencil and pull as tight as I can (with lots of tape) and get back something a bit larger than the pencil. I think if you have a 5 mm mandrel and take your time you could get close to a S&S version.
Bill
I just ruined a couple cables the other night trying to coil them. They fired the flash at first but then after I wound them, they didn't provide enough light to fire my S&S strobes. I have a feeling that the water may have been too hot (not sure. anyone else have this happen?). I also cooled them down quickly in cold water. Whoops. Good thing the cable was cheap. Maybe I'll try again, otherwise, just use then without the fancy coil and just wrap them around my ultra-lite arms.
I have bought a bunch of fiber from monoprice (Toslink) and that stuff works great on a short run of straight fiber (like 5 inches or so) but coiled it just doesn't have the transmission, not because of the coiling (I think) but just because of the length. If you think about how the fiber works, coiling it should have no effect.
Bill
If you think about how the fiber works, coiling it should have no effect.
Bill
You are wrong on this. The more you bend the fiber the bigger the light loss is.
I don't understand why that would be unless you generate micro kinks in the fiber. If the cladding is correct and undamaged, I don't see why there would be a loss. I understand what will happen if I fracture the fibers, but when I use a power meter to measure the throughput of the fiber coiling it does not change the output in any measurable way.
Bill
I don't understand why that would be unless you generate micro kinks in the fiber. If the cladding is correct and undamaged, I don't see why there would be a loss. I understand what will happen if I fracture the fibers, but when I use a power meter to measure the throughput of the fiber coiling it does not change the output in any measurable way.
Bill
Ther is an allowable bending radius but I think there is some slight light loss even before:
In the coil you have many bands so the light loss is accumulating but it shouldn't be that big problem.
I have no experience in doing this but suspect the problem might be with generating lateral micro cracks in the fiber when bending it cold around the mandrell.
Either warming (right through) before wrapping or a two stage process might help.
No, it depends on the internal reflection. The light is kept in the fiber by transparent cladding material with a different refraction index. There is a critical angle when the light is not reflected but leaks out. It actually defines the acceptance cone and also the numerical apperture. When we band the fibers too much the light travells not at a steep angle and leaks out. Actually in my new optical fiber based ring/rim adapter I can see the light leak due to too much bending.
It's similar to the comparison of flat port to dome port. At certain angle our wide angle lens can't see through the flat port but when the surface is bent (dome port) the light can come in (or go out).
Marcell is right about how the cladding works, but experimentally (in my lab at least) coiling to the dimensions of a typical Inon fiber changes the throughput by less than 1 % compared to the straight fiber at least at 528, 633 and 800 nm. You can of course delaminate the cladding from the fiber and then you get into big trouble. Bill
This is slightly OT, but for those of you making your own FO cables, where are you sourcing the connection fittings?
