Introduction of Visual Fault Locator

Many of the problems encountered in troubleshooting fiber optic networks are related to making proper connections. Since the light used in fiber optic systems is infrared (IR) light, which is beyond the range of the human eye and one cannot see it. In order to solve these problems, you need a visual fault locator. Visual fault locator(VFL) is a kind of device which is able to locate the breakpoint, bending or cracking of the fiber glass. It can also locate the fault of OTDR dead–zone and make fiber identification from one end to the other end. This text will give you a brief introduction of visual fault locator.

Working Principle

A powerful visible light from a red diode laser is injected into the fiber, so not only fibers  can be traced, but also high loss points can be made visible. Most applications center on short cables to connect to the fiber optic trunk cables, such as those used in premises cabling or telco central offices. The VFL works best on short cables, up to a few kilometers, thus, it covers the range where optical time-domain reflectometers (OTDRs) are not useful because of the dead zone of the OTDR.

Types of Visual Fault Locator

Visual fault locators generally include the pen type, handheld type and portable visual fiber fault locator.

Pen-style visual fault locator, as showed in the picture below, with a pocket-size, can be carried anywhere easily.

pen type VFL

Hand-held visual fault locator, as the following picture shows, is offered in a range of connector bulkheads styles, from universals to specific connector types.

Handheld VFL

Portable visual fiber fault locator is used to identify fiber and locate faults of single-mode or multi-mode fiber, it is a helpful assistant for finding fault in dead zone of OTDR, it is also a basic maintenance tool for fiber network, LAN, ATM fiber system and telecom network system. The appearance of a portable visual fiber fault locator is showed the following picture.

Portable Visual Fault Locator

Application of Visual Fault Locator

Visual fault locator is a kind of test equipment for testing, troubleshooting and measurement. The VFL is an ideal tool for locating a large number of defects that occur at connection and around fiber cabinets which are hidden in an OTDR “blind-spot” or “dead-zone”. Fiber breaks, faulty connector, sharp bends, bad splices and similar faults can be visually located by light radiated outside the fiber when the light is injected into a fiber. Visual fault locator can boost productivity in the field by providing fast detection, precise fault location, distance, loss, and ORL measurements.

Importance of Visual Fault Locator

The complex network integrated by optical fiber, connector and jumper makes you difficult to find the fault location. So the visual fault locator is an essential tool that quickly and easily locates problem areas in fiber cables. By pinpointing the exact location of fiber damage, technicians can diagnose, troubleshoot and fix the problem timely and efficiently. The VFL is also used for conducting continuous tests and performing fiber identification. With visual fault locator, you can easily isolate high losses and faults in optical fiber cables.

Fiberstore Solution

In terms of its types, applications, importance we can know the VFL is an ideal tool for locating a large number of defects that occur at connection and around fiber cabinets which are hidden in an OTDRs “blind-spot” or “dead-zone”. Fiberstore can not only supply visual fault locators, but also offer a new kind of Fiber laser tester, fiber optic pen, fiber laser pen. If you have any requirements, please contact us at or live chat with us.