Fiber Optics Overview

The term "Fiber Optics" refers to a type of technology used in many different industries including Telecommunications, High-speed Internet, Cable Television, Industrial and Home Lighting and many others. While the specific details vary for each industry, the basic concept is the same: an optical fiber (made of either glass or plastic) is used to guide light from one point to another.

In order to create a fiber optic communications link, three basic components are needed: a light source (used to inject light into the fiber), the fiber itself, and a receiver (to detect the light at the other end of the fiber). Once light is injected into the fiber by the source, it is "trapped" in the core, a phenomenon known as "total internal reflection." This characteristic enables optical fiber to transport light across great distances, even around corners and large bends.

Fiber optic cables (including the cable used in the Fiber Fence and Opti-Mag Systems) carry a specification known as minimum bend radius. The minimum bend radius is the smallest bend that can be applied to the cable at any given point without causing a loss of light. The minimum bend radius for the sensing fiber used here is four (4 cm) centimeters or 1.5 inches. Therefore in order to avoid a loss of light, any loop formed with the sensing fiber during system installation must be larger than eight centimeters (8 cm) or 1.5" in diameter.

Both the Opti-Mag and Fiber Fence systems work by injecting light into one end of the sensing fiber and measuring the amount of light that reaches the Control Unit at the other end of the fiber. If a tripped sensor or other disturbance to the fiber causes the amount of light that reaches the detector to drop below a preset threshold, an alarm signal is generated that is sent out through the dry contact relays on the back of the control unit. When many sensors are interconnected, a Mapping System is available that reveals the exact location of a triggered sensor.