Testing your Fiber-Optic Cables

Testing is used to evaluate the performance of fiber optic components, cable plants and systems. As the components like fiber, connectors, splices, LED or laser sources, detectors and receivers are being developed, testing confirms their performance specifications and helps understand how they will work together. Designers of fiber optic cable plants and networks depend on these specifications to determine if networks will work for the planned applications.

1. Have the right tools and test equipment for the job. * Optical inspection microscope, 100-200X video scope recommended * Source and power meter, optical loss test set (OLTS) or test kit with proper equipment adapters for the cable plant you are testing. * Reference test cables that match the cables to be tested and mating adapters, including hybrids if needed * Fiber Tracer or Visual Fault Locator * Cleaning materials - dry cleaning kits or lint free cleaning wipes and pure alcohol * Optional: OTDR with launch and/or receive cables for outside plant jobs and troubleshooting * Read more about fiber optic instruments below and

2. Know how to use your test equipment
Before you start, get together all your tools and make sure they are all working properly and you and your installers know how to use them. It's hard to get the job done when you have to call the manufacturer from the job site on your cell phone to ask for help. Try all your equipment in the office before you take it into the field. Use it to test every one of your reference test jumper cables in both directions using the single-ended loss test to make sure they are all good. If your power meter has internal memory to record data be sure you know how to use this also. You can often customize these reports to your specific needs - figure all this out before you go it the field - it could save you time and on installations, time is money!

3. Know the cabling network you're testing
This is an important part of the documentation process we discussed earlier. Make sure you have cable layouts for every fiber you have to test and have calculated a loss budget so you know what test results to expect. Prepare a spreadsheet of all the cables and fibers before you go in the field and print a copy for recording your test data. You may record all your test data either by hand or if your meter has a memory feature, it will keep test results in on-board memory that can be printed or transferred to a computer when you return to the office.

A note on using a fiber optic source: eye safety. Fiber optic sources, including test equipment, are generally too low in power to cause any eye damage, but it's still advisable to check connectors with a power meter before looking into it. Besides, most fiber optic sources are at infrared wavelengths that are invisible to the eye, making them more dangerous. Connector inspection microscopes focus all the light into the eye and can increase the danger. Some telco DWDM and CATV systems have very high power and they could be harmful, so better safe than sorry. Read our page on Safety.