Vibrometer

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Functional principle of a laser Doppler vibrometer

A vibrometer (short for laser Doppler vibrometer ) is a measuring device for quantifying mechanical vibrations . It can be used to measure vibration frequency and amplitude.

Vibrometers contain a laser that is focused on the surface to be measured . Due to the Doppler effect, the frequency of the backscattered laser light shifts when the surface to be measured moves . This frequency shift is evaluated in the vibrometer using an interferometer and output as a voltage signal or digital data stream . A scanning vibrometer allows vibrations to be measured over a large area.

application

Vibrometers are used in a wide variety of scientific, industrial, and medical fields. Here are some examples:

  • Aerospace - Vibrometers are used as tools for the non-destructive testing of aircraft components.
  • Acoustics - Vibrometers are standard tools for speaker design. In addition, they have already been used to record the vibration behavior of musical instruments.
  • Architectural vibrometers are used to record the vibration behavior of buildings and bridges (bridge maintenance) .
  • Automotive construction - measurement of the vibration modes of individual components or entire vehicles.
  • Sound velocity measurement : A sound velocity causes a thin film to vibrate. This vibration of the film is measured with a laser Doppler vibrometer and the sound pressure is determined from it.
  • Biology vibrometers were used, for example, to examine the eardrum in the ear or to visualize communication between insects.
  • Calibration - Because vibrometers are calibrated in relation to the wavelength of light, they are used to calibrate other measuring instruments.
  • Hard disk vibrometers have already been used to examine hard disks, especially in the positioning of the read head .
  • Land Mine Finding - Vibrometers have been shown to detect buried land mines. A noise source, for example a loudspeaker, stimulates the floor to vibrate minimally. These vibrations are recorded by the vibrometer. The ground above a buried landmine shows a different vibration behavior than ground without a landmine. Mine detection with single-beam vibrometers, an arrangement of vibrometers, and multi-beam vibrometers has already been carried out successfully.
  • Safety - Due to their property of non-contact vibration measurement, vibrometers are also suitable for recording voices over large distances. With the help of a visual sensor (camera), the vibrometer is aimed at a sound-reflecting surface near the target in order to pick up the acoustic signals.
  • Material research - Thanks to their non-contact measuring method, laser vibrometers, especially scanning laser vibrometers, allow the investigation of material surfaces. This enables defects to be found in crystal lattices or similar materials due to the different scattering behavior of vibrations at these points.

Web links

Individual evidence

  1. ↑ James M. Kilpatrick, Vladimir Markov: Matrix laser vibrometer for transient modal imaging and rapid nondestructive testing . In: Enrico P. Tomasini (Ed.): Eighth International Conference on Vibration Measurements by Laser Techniques: Advances and Applications  (= Eighth International Conference on Vibration Measurements by Laser Techniques: Advances and Applications), Volume 7098 2008, p. 709809, doi : 10.1117 / 12.802929 .
  2. ↑ Bissinger, George. and Oliver, David: 3-D Laser Vibrometry on Legendary Old Italian Violins . In: Sound and Vibration . July 2007. Retrieved January 24, 2013.
  3. ^ Horst Falkner: Monitoring in the construction industry. ( Memento of the original from July 31, 2013 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 1.1 MB) In: The test engineer. Year 2004, issue 4, p. 41. @1@ 2Template: Webachiv / IABot / www.bvpi.de
  4. ↑ Uwe Friebe, Gert Gommola: 90 years of bridge measuring systems on the railways in Germany. In: Measurement technology in construction. Ernst & Sohn Special 2013, p. 36.
  5. ^ William N. Sharpe, Jr., William N. Sharpe: Springer Handbook of Experimental Solid Mechanics . Springer, 4 December 2008, ISBN 978-0-387-26883-5 , p. 834. , p. 834
  6. ^ Q. Leclère, B. Laulagnet: Particle velocity field measurement using an ultra-light membrane . In: Applied Acoustics . tape 69 , no. 4 , 2008, p. 302-310 , doi : 10.1016 / j.apacoust.2006.11.009 .
  7. ↑ Huber, Alexander M, C Schwab, T Linder, SJ Stoeckli, M Ferrazzini, N Dillier, U Fisch: Evaluation of eardrum laser doppler interferometry as a diagnostic tool . In: The Laryngoscope . 111, No. 3, 2001, pp. 501-7. doi : 10.1097 / 00005537-200103000-00022 . PMID 11224783 .
  8. ^ Fonseca, PJ and Popov, AV: Sound radiation in a cicada: the role of different structures . In: Journal of Comparative Physiology A . 175, No. 3, 1994. doi : 10.1007 / BF00192994 .
  9. ^ Sutton, CM: Accelerometer Calibration by Dynamic Position Measurement Using Heterodyne Laser Interferometry . In: Metrologia . 27, No. 3, 1990, p. 133. doi : 10.1088 / 0026-1394 / 27/3/004 .
  10. ↑ Abdullah Al Mamun, GuoXiao Guo, Chao Bi: Hard Disk Drive: Mechatronics And Control . CRC Press, 2007, ISBN 978-0-8493-7253-7, (accessed January 24, 2013).
  11. ↑ Ning Xiang, James M. Sabatier: Land mine detection measurements using acoustic-to-seismic coupling . In: Abinash C. Dubey, James F. Harvey, J. Thomas Broach, Regina E. Dugan (Eds.): Detection and Remediation Technologies for Mines and Minelike Targets V  (= Detection and Remediation Technologies for Mines and Minelike Targets V), Volume 4038 2000, p. 645, doi : 10.1117 / 12.396292 .
  12. ↑ Richard D. Burgett, Marshall R. Bradley, Michael Duncan, Jason Melton, Amit K. Lal, Vyacheslav Aranchuk, Cecil F. Hess, James M. Sabatier, Ning Xiang: Mobile mounted laser Doppler vibrometer array for acoustic landmine detection . In: Russell S. Harmon, John H. Holloway, Jr, JT Broach (Eds.): Detection and Remediation Technologies for Mines and Minelike Targets VIII  (= Detection and Remediation Technologies for Mines and Minelike Targets VIII), Volume 5089 2003, p . 665, doi : 10.1117 / 12.487186 .
  13. ↑ Amit Lal, Slava Aranchuk, Valentina Doushkina, Ernesto Hurtado, Cecil Hess, Jim Kilpatrick, Drew l'Esperance, Nan Luo, Vladimir Markov: Advanced LDV instruments for buried landmine detection . In: J. Thomas Broach, Russell S. Harmon, John H. Holloway, Jr (Eds.): Detection and Remediation Technologies for Mines and Minelike Targets XI  (= Detection and Remediation Technologies for Mines and Minelike Targets XI), Volume 6217 2006 , P. 621715, doi : 10.1117 / 12.668927 .
  14. ↑ Rui Li, Tao Wang, Zhigang Zhu, Wen Xiao: Vibration Characteristics of Various Surfaces Using an LDV for Long-Range Voice Acquisition . In: IEEE Sensors Journal . 11, No. 6, 2011, p. 1415. doi : 10.1109 / JSEN.2010.2093125 .
  15. ↑ Materials research - measuring NDT non-destructively. Retrieved August 29, 2019 .