Phase-preserving methods to visualise ultrasonic fields with schlieren imaging
-
Tim Hetkämper
Tim Hetkämper, M.Sc. graduated from Paderborn University with a degree in electrical engineering in 2018. Since 2019, he has been a research associate at the Measurement Engineering Group at Paderborn University, Germany. His research focuses on methods to visualise ultrasonic fields with the help of schlieren imaging.
,
Kevin Koch
Kevin Koch, B.Sc. is a graduate student at the Measurement Engineering Group at Paderborn University. In 2021, he finished his bachelor thesis on schlieren imaging.
Dr.-Ing. Leander Claes completed his studies in electrical engineering in 2014. Since 2015, he has been a research associate and, starting mid-2016, deputy head of the Measurement Engineering Group at Paderborn University, Germany. His research includes the development of acoustic measurement procedures, with a focus on material and fluid characterisation applications.
Prof. Dr.-Ing. Bernd Henning is head of the Measurement Engineering Group, Faculty of Electrical Engineering, Computer Science and Mathematics at Paderborn University, Germany. His main areas of research are acoustic measurement procedures, ultrasonic and optical measurement engineering as well as biomedical measurement techniques.
Abstract
Schlieren imaging allows visualising local density modulations in optically transparent media, which enables to analyse ultrasonic wave propagation. In typical measurement setups, spatial filtering is applied. Commonly, phase information of the ultrasonic wave is lost, which e.g. prevents accurate tomographic reconstruction. In this work two methods are presented to preserve phase information. The first method relies on the combination of two different spatial filters, while the second method does not require any spatial filtering. The fractional Fourier transform is applied to explain and simulate the effects occurring if the position of one of the optical lenses in a schlieren measurement setup is varied. Exemplary images of ultrasonic waves are shown to demonstrate the application of both methods.
Zusammenfassung
Die Schlierentechnik ermöglicht die Visualisierung lokaler Dichtemodulationen in optisch transparenten Medien. Dadurch kann unter anderem die Ausbreitung von Ultraschallwellen analysiert werden. Üblicherweise wird in Messaufbauten zur Aufnahme von Schlierenabbilddungen ein Ortsfilter eingesetzt. Allerdings geht dabei häufig die Phaseninformation der Ultraschallwelle verloren, was beispielsweise eine getreue tomographische Rekonstruktion verhindert. In dieser Arbeit werden zwei Methoden vorgestellt, welche die Phaseninformation erhalten. Die erste Methode basiert auf der Kombination von zwei verschiedenen Ortsfiltern, während die zweite überhaupt keinen Ortsfilter benötigt. Dazu wird eine der Linsen im Messaufbau verschoben. Die auftretenden Effekte werden mit Hilfe der fraktionalen Fourier-Transformation erklärt und simuliert. Die Anwendung beider Methoden wird anhand von beispielhaften Schlierenabbilddungen demonstriert.
About the authors
Tim Hetkämper, M.Sc. graduated from Paderborn University with a degree in electrical engineering in 2018. Since 2019, he has been a research associate at the Measurement Engineering Group at Paderborn University, Germany. His research focuses on methods to visualise ultrasonic fields with the help of schlieren imaging.
Kevin Koch, B.Sc. is a graduate student at the Measurement Engineering Group at Paderborn University. In 2021, he finished his bachelor thesis on schlieren imaging.
Dr.-Ing. Leander Claes completed his studies in electrical engineering in 2014. Since 2015, he has been a research associate and, starting mid-2016, deputy head of the Measurement Engineering Group at Paderborn University, Germany. His research includes the development of acoustic measurement procedures, with a focus on material and fluid characterisation applications.
Prof. Dr.-Ing. Bernd Henning is head of the Measurement Engineering Group, Faculty of Electrical Engineering, Computer Science and Mathematics at Paderborn University, Germany. His main areas of research are acoustic measurement procedures, ultrasonic and optical measurement engineering as well as biomedical measurement techniques.
-
Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.
-
Research funding: None declared.
-
Conflict of interest statement: The authors declare no conflicts of interest regarding this article.
References
[1] C. Scruby and L. Drain, Laser Ultrasonics – Techniques and Applications, New York, Taylor & Francis, 1990.Search in Google Scholar
[2] S. J. Rupitsch, “Piezoelectric sensors and actuators: fundamentals and applications,” in Topics in Mining, Metallurgy and Materials Engineering, Berlin, Heidelberg, Springer, 2019.10.1007/978-3-662-57534-5Search in Google Scholar
[3] C. Raman and N. N. Nathe, “The diffraction of light by high frequency sound waves: Part i,” in Proceedings of the Indian Academy of Sciences-Section A, vol. 2, Springer, 1935, pp. 406–412.10.1007/BF03035840Search in Google Scholar
[4] W. Stößel, Fourieroptik, Berlin, Heidelberg, Springer, 1993.10.1007/978-3-662-01618-3Search in Google Scholar
[5] W. Lauterborn and T. Kurz, Coherent Optics, Berlin, Heidelberg, Springer, 2003.10.1007/978-3-662-05273-0Search in Google Scholar
[6] J. W. Goodman, Introduction to Fourier Optics, 3rd ed. San Francisco, McGraw-Hill and Roberts & Company, 2005.Search in Google Scholar
[7] C. Unverzagt, S. Olfert, and B. Henning, “A new method of spatial filtering for schlieren visualization of ultrasound wave fields,” Phys. Procedia, vol. 3, pp. 935–942, 2010. https://doi.org/10.1016/j.phpro.2010.01.120.Search in Google Scholar
[8] Texas Instruments, “Dlp6500 datasheet,” no. 10, 2016.Search in Google Scholar
[9] S. Olfert and B. Henning, “Analyse integral erfasster Schallwechseldruckverteilungen in Schlierenabbildungen,” in XXIX Messtechnisches Symposium, DE Gruyter, 2015, pp. 73–80.10.1515/9783110408539-010Search in Google Scholar
[10] T. Hetkämper, D. Dreiling, L. Claes, and B. Henning, “Tomographie des Schallfelds von Ultraschallwandlern mittels Schlierentechnik,” in DAGA 2021 – 47. Jahrestagung für Akustik, Wien, Deutsche Gesellschaft für Akustik e.V. (DEGA), 2021, pp. 1520–1523.Search in Google Scholar
[11] T. Pitts, A. Sagers, and J. Greenleaf, “Optical phase contrast measurement of ultrasonic fields,” IEEE Trans. Ultrason. Ferroelectr. Freq. Control, vol. 48, no. 6, pp. 1686–1694, 2001. https://doi.org/10.1109/58.971722.Search in Google Scholar PubMed
[12] E. Reichel, S. Schneider, and B. Zagar, “Characterization of ultrasonic transducers using the schlieren-technique,” in 2005 IEEE Instrumentation and Measurement Technology Conference Proceedings, vol. 3, 2005, pp. 1956–1960.10.1109/IMTC.2005.1604513Search in Google Scholar
[13] H. M. Ozaktas, Z. Zalevsky, and M. A. Kutay, “The fractional Fourier transform with applications in optics and signal processing,” in Wiley Series in Pure and Applied Optics, Chichester, New York, Weinheim, Jon Wiley & Sons, 2001.10.1117/12.2299085Search in Google Scholar
[14] T. Hetkämper, L. Claes, and B. Henning, “Schlieren imaging with fractional Fourier transform to visualise ultrasonic fields,” in Sensors and Measuring Systems; 21th ITG/GMA-Symposium, VDE VERLAG GMBH, 2022.Search in Google Scholar
[15] H. Ozaktas, O. Arikan, M. Kutay, and G. Bozdagt, “Digital computation of the fractional Fourier transform,” IEEE Trans. Signal Process., vol. 44, no. 9, pp. 2141–2150, 1996. https://doi.org/10.1109/78.536672.Search in Google Scholar
[16] R. Lerch, G. Sessler, and D. Wolf, Technische Akustik, Berlin, Heidelberg, Springer, 2009.10.1007/978-3-540-49833-9Search in Google Scholar
© 2023 Walter de Gruyter GmbH, Berlin/Boston
Articles in the same Issue
- Frontmatter
- Research Articles
- Conformity assessment of photo-optical measurement data registration in legal metrology
- Phase-preserving methods to visualise ultrasonic fields with schlieren imaging
- Design and performance analysis of a novel displacement-based temperature sensor
- On mass dynamics in a closed ecological system, determined with a prototype vacuum mass comparator – a methodological validation study
Articles in the same Issue
- Frontmatter
- Research Articles
- Conformity assessment of photo-optical measurement data registration in legal metrology
- Phase-preserving methods to visualise ultrasonic fields with schlieren imaging
- Design and performance analysis of a novel displacement-based temperature sensor
- On mass dynamics in a closed ecological system, determined with a prototype vacuum mass comparator – a methodological validation study
