T. Hetkämper, K. Koch, L. Claes, and B. Henning, “Phase-preserving methods to visualise ultrasonic fields with schlieren imaging,”10.1515/teme-2022-0112__tm - Technisches Messen, vol. 90, no. 2, pp. 103–112, 2023, doi:10.1515/teme-2022-0112 .

D. Dreiling, D. Itner, T. Hetkämper, C. Birk, H. Gravenkamp, and B. Henning, “Improved determination of viscoelastic material parameters using a pulse-echo measurement setup,”10.5162/SMSI2023/P59__in SMSI 2023 Conference, Nürnberg, 2023, pp. 394–395, doi:10.5162/SMSI2023/P59 .

T. Hetkämper, K. Koch, M. Webersen, and L. Claes, “Application-based learning of signal analysis methods with the help of a graphical open-source software,”10.21427/159K-G445__presented at the SEFI 2023 Annual Conference, 2023, doi:10.21427/159K-G445 .

T. Hetkämper, L. Claes, and B. Henning, “Vorzeichenrichtige tomographische Rekonstruktion von Ultraschallfeldern mit Hilfe der Schlierentechnik,”10.1515/teme-2023-0069__tm - Technisches Messen, vol. 90, no. , pp. 49–54, 2023, doi:10.1515/teme-2023-0069 .

T. Hetkämper, Visualisierung von Ultraschallfeldern mittels Schlierentechnik und fraktionaler Fouriertransformation. Workshop “Messtechnische Anwendungen von Ultraschall”, Drübeck, 2022.

T. Hetkämper, L. Claes, and B. Henning, “Schlieren imaging with fractional Fourier transform to visualise ultrasonic fields,” presented at the 21. ITG/GMA- Fachtagung Sensoren und Messsysteme 2022, Nürnberg, 2022.

L. Claes et al., “Measurement procedure for acoustic absorption and bulk viscosity of liquids,”10.1016/j.measurement.2021.109919__Measurement, Art. no. 109919, 2021, doi:10.1016/j.measurement.2021.109919 .

T. Hetkämper, D. Dreiling, L. Claes, and B. Henning, “Tomographie des Schallfelds von Ultraschallwandlern mittels Schlierentechnik,” presented at the DAGA 2021 - 47. Jahrestagung für Akustik, 2021.

T. Hetkämper, M. Krumme, D. Dreiling, and L. Claes, “A modular, scalable open-hardware platform for project-based laboratory courses in electrical engineering studies,” in SEFI 48th Annual Conference Proceedings - Engaging Engineering Education, Enschede, 2020, pp. 1309–1313.

L. Claes, C. Steidl, T. Hetkämper, and B. Henning, “Estimation of acoustic wave non-linearity in ultrasonic measurement systems,”10.48550/arXiv.2001.05708__arXiv.org, 2020, doi:10.48550/arXiv.2001.05708 .

T. Hetkämper, L. Claes, and B. Henning, “Evolutionary algorithm for the design of passive electric matching networks for ultrasonic transducers,” in 2019 International Congress on Ultrasonics, Bruges, 2019.