Fiber optic testing is necessary in optical installations. Accurate testing result can’t be got without high quality fiber optic testers. And there are various kinds of fiber testers available in the market. Today, this article mainly focuses on introducing several common types of fiber optic testers.
What Should Be tested?
When it comes to fiber optic installation and termination, fiber optic testers cannot be ignored. After the cables are installed and terminated, it’s time for testing. But what should be tested with fiber optic testers? Here are some common parameters which need to be tested.
Power in a fiber optic system is like voltage in an electrical circuit. It’s important to have moderate power. Because too little power may not distinguish the signal from noise and too much power can cause errors too. So it’s important to measure power.
Loss testing is the difference value between the power coupled into the cable at the transmitter end and what comes out at the receiver end. In fiber optic system, many things can result in loss such as dirt, connectors and breaks.
Optical Return Loss (ORL)
Optical return loss is the total accumulated light power reflected back to the source from the complete optical span. It includes the back scattering light from the fiber itself and the reflected light from all the joints as well as terminations. Generally, ORL is expressed in decibels (dB). And a high level of ORL will affect the performance of transmission systems.
In addition, some optical testers also can be used for troubleshooting.
Common Types of Fiber Optic Tester
Having known what should be tested in fiber optic testing. Now it’s time to know something about fiber optic testers. Generally, the common types of fiber optic test instruments are visual fault locator (VFL), OTDR (Optical Time Domain Reflectometry), optical power meter, optical multimeter, etc. Following is a brief introduction to the usual types of fiber optic tester.
OTDR comprising a laser source and an optical detector operates like radar. It generates short pulses of light and then samples the light scattered back by fiber segments and reflected by connections and other events. OTDR is the main piece of test equipment that is used to analyze a fiber optic link. In addition, as it is possible to calibrate the speed of the pulse as it passes down the fiber, the OTDR also can measure time.
VFL is an essential tool for testing cable continuity and locating visual faults. As is known to all, when light encounters a break or sharp bend, it scatters, and scattered light can be observed emerging from the cable. By emitting a laser beam of red light, the VFL can quickly illuminate fiber breaks, damaged connectors, detective splices and tight fiber bends. It even can locate the breaks in a short patch cord, which an OTDR cannot detect. Therefore, VFL is a helpful assistant to the dead zone of DTOR. And it also a basic maintenance tool for fiber network, LAN (Local Area Network) and telecommunication network system.
Optical Power Meter
Optical power meter is a device to measure the power of an optical signal. Its function is to display the incident power on the photodiode. When testing the signal, optical power meter is connected to different places. When testing transmitted power, t is connected directly to the optical transmitter’s output, but it will be connected to the fiber system while testing the received power. In a word, optical power meter is a the primary test instrument for fiber optic networks, as measuring optical signal power is a necessary task for any fiber technician.
Optical multimeter, also called optical loss test set, is an instrument that measures several optical parameters such as optical power and wavelength. It adopts an optical laser source and an optical power meter into one handheld instrument, which makes it easy to measure the optical loss of optical fiber links, optical components and fiber networks.