Where is the fiber optic sensor installed illustration

Fiber optic sensors are installed on surfaces, embedded in materials, attached to structures, or placed inside equipment depending on the application.

Surface and Structural Installations

Fiber optic sensors can be mounted on metallic or composite surfaces to measure strain or vibration. For example, in structural health monitoring, the fiber is often bonded to the surface using adhesives like M-Bond 200 or AE-10, and a protective layer such as RTV silicone is applied to shield the fiber from environmental effects like moisture or mechanical damage (Sensuron) . Tape can also be used for temporary or non-critical applications, though it is less reliable than adhesive bonding .

Embedded Installations

In civil engineering, fiber optic sensors can be embedded in concrete. This can be done by placing the fiber in a groove for shallow installations or casting it directly into the concrete for deeper measurements. Embedded fibers allow distributed strain monitoring throughout the material but require careful consideration of environmental effects such as temperature and moisture .

Perimeter Security

For security applications, such as the FiberPatrol fence-mounted intrusion detection system, the fiber optic sensor cable is attached along a perimeter fence. The system detects vibrations caused by climbing, cutting, or lifting the fence. The fiber cable includes dedicated sensing fibers and is connected to a controller that transmits laser light and analyzes back-scatter reflections to locate disturbances .

High-Voltage Equipment

In electrical applications, fiber optic hot spot temperature sensors are installed inside high-voltage transformer windings. The sensors are placed in contact with the winding's hottest spots and secured using radial spacers to prevent crushing during thermal expansion or current surges. Sensor cables are routed carefully from the winding to tank wall feedthroughs for monitoring .

Narrow or Confined Spaces

Fiber sensors can also be installed in tight or narrow locations where traditional sensors cannot fit. The flexible fiber unit allows the sensing section to be positioned close to the object, enabling detection of objects or changes in the environment without physical contact .

Summary

Depending on the application, fiber optic sensors can be:

• Surface-mounted on metals or composites for strain or vibration monitoring.
• Embedded in concrete or other materials for distributed sensing.
• Attached to fences for perimeter security.
• Placed inside equipment like transformer windings for temperature monitoring.
• Installed in narrow spaces for object detection. These installation methods ensure accurate sensing while protecting the fiber from environmental and mechanical stresses.