Automated Measurement Grid Generation for Scanning Laser Doppler Vibrometers

  • L. Pesaresi
  • C. W. Schwingshackl
Conference paper
Part of the Conference Proceedings of the Society for Experimental Mechanics Series book series (CPSEMS)


Full field measurement techniques can provide fast, accurate and detailed vibration response data for finite element model validation and are being wildly used in industrial applications. A Scanning Laser Doppler Vibrometer (SLDV) measures the full field operating deflection shapes of a structure by changing the location of the laser spot on the target surface. However the setup of a measurement and in particular the measurement grid definition, can take up a significant part of the overall measurement time. To optimise the setup time a novel technique for SLDV measurement grids has been developed. The suggested method includes an automated identification of the vibrating target, based on the measured vibration signal of a scan covering the entire field of view of the LDV. Alpha-shape techniques for target identification and geometric algorithms for shape recognition are used to define the measurement area. Novel approaches for symmetry and orientation capture allow the generation of point grids and continuous patterns for various target shapes. The introduced approach allows a quick SLDV setup of the full field scan with a minimum input from the user.


Continuous scanning LDV Full field measurement Measurement grid generation Symmetry identification Alpha shape 



The authors are grateful to Campusworld/Università Politecnica delle Marche for providing some financial support for this work.


  1. 1.
    Slangen P (1993) Electronic speckle pattern interferometry (ESPI): a fast technique for the detection and visualization of proper vibration modes. Eur J Mech Environ Eng 38(2):67–72Google Scholar
  2. 2.
    Van der Auweraer H, Steinbichler H, Vanlanduit S, Haberstok C, Freymann R, Storer D, Linet V (2002) Application of stroboscopic and pulsed-laser electronic speckle pattern interferometry (ESPI) to modal analysis problems. Meas Sci Technol 13(4):451–463Google Scholar
  3. 3.
    Sriram P, Craig JI, Hanagud S (1992) Scanning laser Doppler techniques for vibration testing. Exp Tech 16(6):21–26Google Scholar
  4. 4.
    Tirabassi M, Rothberg SJ (2009) Scanning LDV using wedge prisms. Opt Lasers Eng 47(3–4):454–460Google Scholar
  5. 5.
    Sriram P, Hanagud S, Craig JI (1992) Mode shape measurement using a scanning laser Doppler vibrometer. Int J Anal Exp Modal Anal 7(3):169–178Google Scholar
  6. 6.
    Polytec Scanning Vibromter Software 8.4, Software manual, 41031-Man-Vib-PSV-Soft8.4-0706-01e, Polytec, GermanyGoogle Scholar
  7. 7.
    Martarelli M, Ewins DJ (2006) Continuous scanning laser Doppler vibrometry and speckle noise occurrence. Mech Syst Signal Process 20(8):2277–2289Google Scholar
  8. 8.
    Martarelli M (2001) Exploiting the laser scanning facility for vibration measurements. PhD thesis, University of LondonGoogle Scholar
  9. 9.
    Stanbridge AB, Ewins DJ (2006) A review of 10 years of continuous-scan LDV developments. In: Proceedings of international conference on noise and vibration engineering ISMA2006, vol 1–8, Leuven, Belgium, pp 3165–3179Google Scholar
  10. 10.
    Owen M (2007) Practical signal processing. Cambridge University Press, CambridgeGoogle Scholar
  11. 11.
    Seul M, O’Gorman L, Sammon MJ (2000) Practical algorithms for image analysis: description, examples, and code. Cambridge University Press, CambridgeGoogle Scholar
  12. 12.
    Davies ER (2005) Machine vision: theory, algorithms, practicalities, 3rd ed. Elsevier Science, AmsterdamGoogle Scholar
  13. 13.
    Jain R, Kasturi R, Schunck BG (1995) Machine vision. McGraw-Hill, New YorkGoogle Scholar
  14. 14.
    Edelsbrunner H, Kirkpatrik DG, Seidel R (1983) On the shape of a set of points in the plane. IEEE Trans Inf Theory 29(4):551–559Google Scholar
  15. 15.
    Edelsbrunner H, Mücke EP (1994) Three-dimensional alpha shapes. ACM Trans Graph 13(1):43–72Google Scholar
  16. 16.
    Xu X, Harada K (2003) Automatic surface reconstruction with alpha-shape method. Vis Comput 19(7):431–443Google Scholar
  17. 17.
    De Berg M, Cheong O, Van Kreveld M, Overmars M (2008) Computational geometry: algorithms and applications. Springer, Berlin/New YorkGoogle Scholar
  18. 18.
    Carpinteri A (1997) Structural mechanics. Taylor & Francis, LondonGoogle Scholar

Copyright information

© The Society for Experimental Mechanics 2014

Authors and Affiliations

  1. 1.Imperial College LondonLondonUK

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