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May 31, 2006

Termination of Fiber Optics

I learned how to do something really neat today. I can now terminate a fiber optic cable using LC ends. Now, before you go "ooh" and "aah", it's important to note that this is the easiest possible way to field terminate a fiber cable. These ends are designed to install fast, as in under a few minutes. There's no polishing or epoxy required.

Here's what a LC terminated cable looks like.

Here's the jist of how it works:

1. Strip the outer coating which in the world of fiber optics is called the buffer.
You have to measure back 40mm to make the strip, make a mark and use wire strippers to pull the buffer off. You have to be careful here, otherwise you can break the fiber.

2. Remove the kevlar string.
This stuff just goes everywhere and is hard as hell to cut. A typical pair of scissors just won't cut it. You really need scissors that come in a fiber optic cable kit.

3. Once the 40mm buffer has been removed, remove 4mm more.
Since we've removed the kevlar string from the original stripping, we're going to uncover 4mm more. This 4mm of string is important for the stability of the termination.

4. Take the termination kit and put on the boot, the snap-on clamp thingie, and the metal jacket ring.
All of these things come with the termination kit. They're all important, and need to be put in place in the order that I gave before you strip the fiber clean.

5. Strip the cladding, the color coating covering the fiber.
To do this, you have to use a special tool that cuts the cladding just right and allows you to pull it off so to expose the fiber. It's important to note that you will need to make this cut roughly 4mm from the base of the buffer, which in turn will leave 4mm of cladding exposed. While holding pressure and holding the fiber cable at a straight line, slowly pull the tool towards the end of the fiber to remove the cladding. Too fast or too hard, and the fiber will break and you'll have to start again.

6. Clean up the fiber and break it to length.
Once the cladding is removed, you'll have 40mm of bare fiber. You won't want to use the entire 40mm. Instead, you use a tool to measure out a certain amount of exposed from the exposed 4mm cladding. A clamp holds the fiber in place while a razor edge makes a clean cut and allows you to break the line clean.

7. Setup the terminator to accept the exposed fiber.
At this point, the fiber cable is ready to go. It's just a matter of setting up the terminator to accept the cable and then be crimped. This portion is hard to explain unless you have the crimp tool in front of you. Needless to say, it requires a laser light, a fiber jumper cable, an adaptor to plug into your terminator end and a crimp tool to hold it all.

8. Insert the fiber and crimp the terminator.
Using the laser light, you can determine if your fiber is inserted into the terminator properly. If it's not making a good connection, the laser light bleeds out. Once a good connection is made, then the light goes out. A simple press of a lever crimps the fiber into place on the terminator. At this point, there is a metal jacket that is crimped between the terminator and the cable to hold them in place and provide strength to the overall end.

9. Place the boot and clip in place.
Once the crimps are done, the boot and clip that hold everything together are slid up from the fiber cable and locked into place on top of the metal jacket that is now crimped to the cable and terminator.

10. Rinse and repeat.
This is only one end. You need to put another terminator on the other end of the cable. Then you need to test it out and make sure that it's all working properly. If not, then you've wasted two terminators and need to start all over again.

Sounds like a ton of fun, eh? And just think ... this is the EASY way to do it.

Bleh.

~out...

Posted by ed at May 31, 2006 08:20 PM

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