Why Would You Need To Connect Fibers Together?
- You cut your fibers too short.
- You have a modular system.
- Fibers are too short to get to the LampLighter Box.
- Extend your signal or lamp to reach the Lamplighter
(for longer runs).
You can find our connecting kits located here.
Tools You’ll Need
Syringe with index matching fluid
Aluminum tubing
Crimp tool
Steps To Connect The Fibers:
- Make sure each fiber is cleanly cut at the ends.
- Take Aluminum tubing and insert the first side until it comes out the other end of the tubing.
- Take a syringe filled with index matching fluid and put a small amount on the end of fiber.
- Draw the coupling tube back over the fiber.
- Take a syringe filled with index matching fluid and put a small amount on the end of the other fiber.
- Put the second fiber into the aluminum tube.
- Use crimpers to crimp each side of the tube.
Fiber Optic Cutting:
You can cut a plastic fiber with a slicing action using a sharp utility knife, or a cutter that has a shearing action, that is, the blades cross in front of each other (like a pair of scissors), compared to pinching the object in the cut.
Reattaching Fibers:
You can reattach fibers with fiber connectors, or a home made solution, by inserting fibers into a tube with an internal diameter, ‘ID’, close to the fiber being used. You can also insert the two fiber ends into an aluminum or plastic tube that has a similar or matching ID to the fiber and then crimping the ends gently to hold the joint together.
The result will be adequate for many applications, although the amount of light will be diminished by about 40%.
Fiber Optic Polishing:
Generally, polishing is unimportant for the hobbyist. Fiber polishing is important for data transmission where multiple joins must be made over miles of fiber runs, however, whilst polishing will improve the light communication, the effect is an improvement of only 4%. As the eye cannot detect such a small change in intensity (the threshold is around 5%) polishing plastic fibers is the least important factor and can be considered unnecessary.
Index Matching
"Index matching" is probably the most easily overlooked and yet the most important factor in minimizing light loss when coupling fibers. Once again, importance depends on the application.
If the intent is to use the fiber optics to only allow the eye to see that there is a light, like lights from a train engine, or headlights on a car, or even lights from a ceiling, then index matching may not provide much benefit. On the other hand, if the intent is to illuminate an object, then you’ll want to retain as much light as possible. This makes index matching important.
So what is "index matching"? It attempts to remove the problem of an air gap, usually by filling the gap with a fluid. The whole reason that fiber optics are such a good conductor of light is that there is a difference in the density (Refractive Index, commonly referred to as 'RI') of the fiber compared to its surroundings. This keeps the light inside the fiber. When the light reaches the end of a fiber where there is an air interface, there is a mismatch of RI and a significant amount of the light will be reflected back from the fiber end or scattered (refracted) away from the end surface of the fiber. This results in a 40% light loss. If a substance is used to couple the fibers that have the same or very close refractive index then these losses will be minimized.
Adding Coupling Fluid to Fiber.
The typical plastic fiber is PMMA and has a refractive index of 1.5. So selecting a coupling fluid that has a similar refractive index and is optically clear will be a good candidate as an index matching fluid as it essentially removes the effect of the air gap. As a result, one can couple fibers with only a 20% loss of light, which is a considerable improvement in performance.
Trainz has a solution that includes a syringe with an index matching fluid and aluminum tubes.
