Using fibre optic data cables decoratively - how to feed light?

Thread Starter

seanspotatobusiness

Joined Sep 17, 2016
199
There's a computer game with a feature in the map that I find interesting and would like to replicate. There are masses of cables spilling out of some places and the cables appear to have random red lights sprinkled throughout them. It seems like the light is inside the insulation of the wires and I suppose, but I don't really know, that maybe they're supposed to be broken fiber optic cables? I've seen images online of broken fiber optic cables and they look a lot like this. I was thinking I could get some used data cables on eBay, snap them in one or two places and attach bright red LEDs but how would I attached the LEDs? Could I just cut off the data connectors and put the light source against the centre of the fibre? Can I expect to get much light through the insulation (I'd buy light-coloured cables, not black) from LEDs or would they need lasers? Laser diodes don't seem very expensive.

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djsfantasi

Joined Apr 11, 2010
6,334
Light in a fiber optic cable comes from a light source at one end of the cable. The light that appears to be inside the cable is actually light reflected by this terminal light source. Light on the edges of a cable comes from the way the cable is manufactured. “Cladding” this coating doesn’t usually show this light, because the cladding is manufactured so this reflection maximizes the light reflected from one end of the cable to the opposite end. If one cable shows a red light, then it has a red light at one end.
 

Thread Starter

seanspotatobusiness

Joined Sep 17, 2016
199
Would breaks likely be brighter if I used an LED source or a laser diode? The laser diodes seem to be a lot cheaper than the LEDs with little heatsinks attached and grub screws for attaching to the end of a fiber optic.
 

djsfantasi

Joined Apr 11, 2010
6,334
If the light source is visibly brighter, than a cut cable will be brighter. So you might use one or more LEDs to light normal cables and use separate LEDs at a higher current for the cut cables.

Not that the diameter of data cables is very small. Hence you won’t get a large light source. And secondly, data cables are made to minimize light leakage, so you’ll have little or no light from their sides.
You can dip the ends of the cable into a thick glue, such as the old school Testor’s plastic glue with fillers. That will create a lense to disperse the light.
 

Reloadron

Joined Jan 15, 2015
5,337
Years ago I played around with doing stuff like this. You can buy a few hundred feet of this stuff for a few bucks or similar fibers or maybe hack a fiber cable. I made bundles and placed them in a plastic drinking straw and opposing them a LED using red, green and blue LEDs. I did use bright LEDs. I used epoxy (two part) to hold things and then placed it in black heat shrink sleeve. I have no idea how much you would gain with a LASER diode but today I would use a bright RGB LED and use color and fade effects from a uC like an Arduino, PICAXE or similar. You can also just buy a fiber optic lamp and be done with it for a few bucks. :) Using a red LASER you would be stuck with red and not easily get the fade effects or different colors. You can buy red LASER diodes on Amazon for $12 a pack of 20 or likely less if you shop around. A word to the wise. They claim 5 Volts and they do work fine but with 5 volts seem to have a short life. This can be extended by placing about a 37 Ohm resistor in series with them.

Ron
 

SamR

Joined Mar 19, 2019
2,006
Think of fiber as a very small thread of glass. How much light is transmitted through the broken edge of glass??? In order to even work correctly for data communication the face of the fiber has to be polished to a mirrorlike finish to prevent light signal degradation. There are lamps made using plastic fibers with a shielded light on one end and the loose fibers on the exposed end. Proper end prep is suggested. YMMV
 

Reloadron

Joined Jan 15, 2015
5,337
Think of fiber as a very small thread of glass. How much light is transmitted through the broken edge of glass??? In order to even work correctly for data communication the face of the fiber has to be polished to a mirrorlike finish to prevent light signal degradation. There are lamps made using plastic fibers with a shielded light on one end and the loose fibers on the exposed end. Proper end prep is suggested. YMMV
Yeah, I did notice my first attempts really sucked. Then I read somewhere about the ends. Now no laughing. I always have Flitz on hand so rather than rouge I put some Flitz on a buffing wheel. I hand held small bundles as best I could and shoved them into my felt bob wheel. Their ability to collect and conduct light improved considerably. Now anyone who has actually buffed out anything using a wheel knows it is not a very clean process as stuff flies everywhere and "stuff" is putting things mild.

Ron
 

shortbus

Joined Sep 30, 2009
7,597
In order to even work correctly for data communication the face of the fiber has to be polished to a mirrorlike finish to prevent light signal degradation.
That's true for data transfer. But back in the1990's working at GM Packard Electric, they didn't do the polishing on the fiber optic cables used for the fender top turn signal monitors used in Cadillac's and Oldsmobile's. they just sheared the cable to length and plugged it into the lenses. some how a couple of feet of the cable followed me home one day.

I work on and own old Harley's. The old pan heads and other engines have the timing mark on the flywheel and you take a plug out to see it, when doing that oil mist sprays out of the hole and you can't really see the mark easily. They sell a clear plastic plug when to use when setting the timing, but you still can't see the mark well. So I took one of those plugs an d drilled ahole in it to put a length of fiber optics in it, then made a cap to put on the timing light, with a hole for the other end of the fiber. Now I can see the timing mark just fine.

https://jalopnik.com/these-tattle-tales-are-americas-weirdest-secret-car-pa-1238802149
 
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