Testing of Fiber Optic Systems

For technicians who think they can use a few meters and connect cables, connect things and get a valid reading like that, I humbly suggest that your days are days of confusion, frustration, negative criticism and bad and invalid readings. Perhaps some upset supervisors and disgruntled customers.

Preparation:

Sometimes, people say that preparation is 90% of the work. Nothing is more true in fiber optic testing.

To start:

A clean test area is the first requirement. A table top, an inverted cardboard box or any available surface will do so. We generally do not have ideal conditions, but wherever we test, the surface must be clean. Sometimes a tablecloth from a dollar store solves many problems.

Clean the surface with alcohol and wipes, preferably lint-free wipes.

Remove fluff or dust with the air lamp. We prefer to use an air lamp because it leaves no residue and does not need to be recharged.

Verify that the indicators defined on this clean surface are clean. I hope they were in a sealed box. Clean them if in doubt. Make sure they are clean and dust-free around the connector connection points.

Verify that the reference cables are clean before placing them. Ideally, they will be in a clean zip bag.

A type of microscope is required to view the connector end.

Test meters:

Verify that the meters have enough battery. Something below 9 volts is not enough, especially in your light source.

Check that the counter has been leveled. Otherwise, expect them to be dirty and read incorrectly.

Make sure that both meters perform the test at the desired wavelength (λ).

Do your tools work? If in doubt, activate both, set the same wavelength and connect a clean correction cable to each other. Put your energy meter in dBm and you will read the energy from the light source. How much it costs depends on the mode and power of the meter. For example; a 1550 laser source can consume 95 uW of energy. Know your counters and know what to expect.

Test cables (reference cables):

You should have two and, ideally, three of the reference cables needed for each type of fiber you need to test.

Reference cables should be 1-3 meters long. They must be the same size and type as the fiber we are testing. The closer they get, the smaller the variable.

Check each reference cable to make sure it is clean.

Remember, if you insert a dirty connector into a clean connector, you will now have two dirty connectors. If they are dirty, clean them with alcohol and a dry cloth or any other effective method. Check them again and connect them if they are clean.

The covers are clean. They are generally not. We can clean them with a polyester brush. Clean it first with a bottle brush dipped in alcohol. Then dry with the other end of the brush. We can also use the polyester pipe cleaner to clean a dirty joint.

You need joints to tie the strings. They can be SC / SC, ST / ST, LC / LC, LC / SC or many other combinations. Make sure they are clean. If in doubt, clean them with alcohol and remove the dust with the air lamp. For all tests, choose good quality joints, exclusive mode with ceramic inserts for greater accuracy. Keeping test joints in a zippered bag is an inexpensive way to keep them clean.

What next?

Congratulations, you are now ready to test. Guess what? Everything you did at this point was necessary and will save time when starting the test. It will also help to ensure that your readings are correct. There is no guarantee that it will, but you have removed many variables.

Test methods

Method 1 - Single Termination Test:

This test will provide us with the loss of the tested cable, including the loss of the connector connected to the reference connector. If the fiber optic cable is located a few meters away, the loss will be negligible.

What it takes:

Optical test kit, including the appropriate light source and energy meter

Reference cable (launch) of the same type and size of fiber as the system we are testing, with connectors compatible with the test meters.

Adapters to fit the connectors on the cable under test and on the power meter.

Procedure:

Verify that all connectors, adapters and the corresponding work area are clean.

Switch on the appliance, allowing time to stabilize and reach room temperature.

Connect the boot cable to the light source and leave it connected during the test.

Set the Zero dB reference on the energy meter. Let it stabilize.

Read More : fibre optic installation jobs