Optical Fiber Testers

Optical fiber requires a unique class of cable testers. Just like copper-cable testers, optical fiber testers are specialized. Figure 1 shows a simple continuity tester that verifies light transmission through the cable.

Figure 1: An optical fiber continuity tester

Another type of optical fiber test device is the power meter (also known as an attenuation tester), such as the one shown in Figure 2. Like the continuity tester, the power meter tests whether light is making its way through the cable, but it also tests how much of the light signal is being lost. Anyone installing fiber-optic cable should have a power meter. Most problems with optical fiber cables can be detected with this tool. Good optical fiber power meters can be purchased for less than $1,000.

Figure 2: An optical fiber power meter

Note

An attenuation tester checks for how much signal is lost on the cable, whereas a continuity tester only measures whether light is passing through the cable.

Many high-end cable testers, such as those available from Hewlett-Packard, Microtest, and others, can test both optical fiber and copper cables (provided you have purchased the correct add-on modules). You need to know a few points when you purchase any type of optical fiber tester:

• The tester should include the correct fiber connectors (ST, SC, FC, LC, MT-RJ, etc.) for the types of connectors you will be using.
• The tester should support the type of fiber-optic cable you need to test (single-mode or multimode).
• A power meter should test the wavelength at which you require the cable to be used (usually 850 or 1,300nm).

Professional fiber-optic cable installers usually carry tools such as an OTDR that perform more advanced tests on optical fiber cable. OTDRs are not for everyone, as they can easily cost in excess of $30,000. However, they are an excellent tool for locating faults.