Fiber optic sensing solutions for demanding applications

Kistler engineer demonstrating a fiber optic sensing system with real-time measurement data visualization.

Distributed strain, shape and temperature sensing based on fiber segment interferometry (FSI)

Kistler-exclusive fiber segment interferometry, or FSI, brings distributed fiber optic sensing to applications where measurement precision, speed, and spatial insight are critical. It allows engineers to monitor physical changes along the fiber, capturing both static behavior and fast dynamic effects.

Fiber segment interferometry (FSI) divides the optical fiber into multiple sensing segments using integrated reflectors. The system evaluates each section individually to generate spatially resolved measurement data along the sensing path.

This measurement principle creates a flexible basis for different sensing tasks, especially where conventional electrical sensors provide limited insight or are difficult to apply.

Fiber optical sensors (FOS) and an opto-electric interrogator: to be connected for data acquisition and processing

See how FSI works in detail

What can be measured with FSI technology?

Depending on the sensor configuration and installation, FSI can be used to measure or derive a broad range of physical parameters along the sensing fiber, including:

Strain

Shape

Temperature

Vibration and acceleration

Pressure

Torsion

Acoustic emission

Force

Ultra-thin fiber segment interferometry (FSI) strain sensor 2071A, 155 µm diameter, with optical connector.

Ultra-thin fiber segment interferometry (FSI) strain sensor 2071A with 155 µm diameter, shown with its optical connector and a match for scale. The compact sensor design enables integration into tight spaces and lightweight structures.

Get application-specific guidance

Our experts are just a click away.

Why choose fiber segment interferometry

Fiber segment interferometry – selected performance data

Values depend on sensor type, sensor configuration, interrogator version, and application setup. The following figures show selected capabilities of FSI-based products.

FSI vs. FBG: Selecting the right sensing principle

Fiber segment interferometry (FSI) and fiber Bragg grating (FBG) sensing are both fiber optic measurement technologies with different sensing principles. FBG provides point-based data at defined grating locations, while Kistler FSI solutions generate distributed measurement data along segmented fiber sections. FSI is especially suitable for high-speed, high-resolution applications with multiple sensing segments.