Structural integrity inspection and monitoring by magneto-optic sensors

Martin J. Dudziak

doi:10.1117/12.335717

8 January 1999 Structural integrity inspection and monitoring by magneto-optic sensors

Martin J. Dudziak

Proceedings Volume 3525, Mobile Robots XIII and Intelligent Transportation Systems; (1999) https://doi.org/10.1117/12.335717
Event: Photonics East (ISAM, VVDC, IEMB), 1998, Boston, MA, United States

Abstract

Non-destructive testing for cracks, fissures, fatigue stress, and corrosion has been demonstrated using eddy- current induced magnetic fields measurable by sensors with Faraday magneto-optic properties. A novel class of such sensors has been developed, the MODE sensor, using Fe-Ga thin-films of the general form (R, Bi)3 (M, Fe)5-12 with R equals (Y, Lu, Tm, or other rare earth ions) and M equals Ga or Al. These films are characterized by very high uniaxial anisotropic field, Faraday rotation, absorption coefficient, and MO figure of merit, significantly improving sensitivity over previous thin film compositions. These properties enable their use in highly compact portable or remotely operated devices and requiring either no eddy current or else brief microbursts of electric current rather than lengthy application of steady current in order to induce magnetic fields within observed structures. A portable system for the testing of bridge structural components, fuel tanks, gas cylinders, and other metallic structures has been designed. This apparatus makes use of a compact portable computer into which video output from the MODE sensor unit received. Using a conventional software interface the operator is able to view the same structure in real time and to apply an array of image processing refinement techniques for improving the resolution of the image. Images may be stored as a constant video stream or as a set of individual snapshots. Additional features that enhance the utility of the system for mobile inspection tasks are discussed. These include the incorporation of a pattern recognition training algorithm and library for operator-enhanced identification of structural defects and condition assessments, as well as the broadcast of image and location data via wireless link to a central server for distribution to consulting engineers and for access of Microstation-type CAD files via a web browser interface.

Citation Download Citation

Martin J. Dudziak "Structural integrity inspection and monitoring by magneto-optic sensors", Proc. SPIE 3525, Mobile Robots XIII and Intelligent Transportation Systems, (8 January 1999); https://doi.org/10.1117/12.335717

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