Cost-effective industrial-grade strain-sensing based on OPI

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Avago Technologies is announcing a cost-effective polymer optical fibre (POF)-based strain sensor for industrial applications. Based on a patented optical phase interrogation (OPI) technique developed by Avago Technologies, the product enables the readily available POF to be used as a high-precision strain sensor on par with current fibre Bragg grating (FBG)-based strain sensors for a broad range of applications including wind-blade load management in wind turbines and structural health monitoring for a variety of other structures.

OPI sensor features:

  • Uses cost-efficient, mass producible polymer optical fibre as the sensor element
  • Has a high elastic strain range (>5 per cent) giving a large dynamic range
  • Easy handling and easy installation
  • High sensitivity and accuracy
  • EMI/EMC immunity
  • Rugged sensor electronics for sensing gauge implementations

The optical sensor employs the POF to form a ‘meander path’ sensor array that allows a single fibre to form multiple loops that fit in a confined area. These loops, when strained, will alter the phase of an optical signal injected into the fibre. A separate reference loop that is not strained surrounds the meander path and is used to compare the reference signal with the strained signal, and the difference in phase between the two signals can be converted into the strain measurement. The reference fibre simultaneously provides temperature compensation. Since the sensing array only contains optical fibres, it is immune to EMI and EMC-related interference and is completely electrically isolated from the rest of the system.

Martin Weigert, general manager of Avago’s Industrial Fiber Product Division explains: “Avago Technologies has supplied large quantities of POF cables and communication modules for industrial networking and data communication applications and has amassed a significant amount of experience in both markets.” By leveraging that experience, the development of the industrial optical sensing technology is a natural extension of the company’s core competence, allowing the company to address a fast-growing market. Weigert continues: “Our proprietary optical phase interrogation method has enabled us to offer a disruptive strain sensing solution using POF – a worthy alternative to conventional strain sensing technologies, electrical and optical, for a number of applications.”

Avago has engaged in a number of applications connected to the wind energy industry and is currently installing sensors into a multi-megawatt conceptual turbine for both wind blade and tower load monitoring. In this market the technology plays out all its advantages offering a rugged alternative to conventional strain measurement technologies.

Avago has assembled a developer’s kit to help designers test and evaluate the sensor technology. The kit consists of a length of polymer optical fibre, the optical phase interrogator, and all the necessary documentation to create a strain sensor with the fibre and evaluate the results. The developer kit will be available starting in January of 2014.

Avago is currently evaluating the implementation of its technology for a number of applications. For evaluation prior to market release please contact your local Avago sales representative for further information regarding the technology and the availability of the evaluation kit. Follow the link for further information on the Avago POF strain sensor.

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