FIBRE BRAGG SENSORS COMPARED WITH ELECTRICAL STRAIN GAUGES FOR USE IN FORCE MEASUREMENT - PROSPECTS AND POTENTIALS

Thomas Kleckers

Abstract

This article deals with the technical properties of fiber Bragg gratings with regard to their use as the strain-sensitive element in force transducers.<br />Electrical strain gages are widely used in modern, precise force transducers. The electrical strain gage provides both outstanding technical properties and cost-effectiveness.<br />Besides the electrical strain gage, the measurement principle of fiber Bragg-based sensors has recently become established. First applications in experimental mechanics have shown that this technology offers a lot of potential.<br />Optical strain gauges are available on the marked since one year and are proofed in many applications.<br />These sensors are mainly based on so-called fiber Bragg gratings. Such a Bragg grating uses a great many reflection points at regular spacing. At each of these points, part of the radiated light is reflected. The reflected light interferes (constructive interference) and generates a reflection peak. This peak shows a characteristic wavelength which is dependent on the spacing of the reflection points.<br />The following sketch shows a Bragg grating in a fibre and its influence on the spectrum of the transmitted and reflected light.<br />This article presents the properties relevant to use in the manufacture of transducers such as:<br />- Creep<br />- Temperature behaviour<br />- Drift<br />- Electromagnetic compatibility<br />and others and compares them with the properties of electrical strain gages.

Keywords

optical strain measurement, Fibre-Bragg gratings, optical force measurement

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IMEKO-WC-2009-TC3-144.pdf

DOI

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IMEKO TC

TC3 - Measurement of Force, Mass, Torque, and Gravity

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