Hetkämper, Tim, Kevin Koch, Leander Claes, and Bernd Henning. “Phase-Preserving Methods to Visualise Ultrasonic Fields with Schlieren Imaging.”https://doi.org/10.1515/teme-2022-0112__Tm - Technisches Messen 90, no. 2 (2023): 103–12.https://doi.org/10.1515/teme-2022-0112 .

Dreiling, Dmitrij, Dominik Itner, Tim Hetkämper, Carolin Birk, Hauke Gravenkamp, and Bernd Henning. “Improved Determination of Viscoelastic Material Parameters Using a Pulse-Echo Measurement Setup.”https://doi.org/10.5162/SMSI2023/P59__In SMSI 2023 Conference, 394–95. SMSI - Sensor and Measurement Science International. Nürnberg: AMA Association For Sensors And Measurement, 2023.https://doi.org/10.5162/SMSI2023/P59 .

Hetkämper, Tim, Kevin Koch, Manuel Webersen, and Leander Claes. “Application-Based Learning of Signal Analysis Methods with the Help of a Graphical Open-Source Software.”https://doi.org/10.21427/159K-G445__In SEFI 51th Annual Conference Proceedings - Engineering Education for Sustainability. SEFI, 2023.https://doi.org/10.21427/159K-G445 .

Hetkämper, Tim, Leander Claes, and Bernd Henning. “Vorzeichenrichtige Tomographische Rekonstruktion von Ultraschallfeldern Mit Hilfe Der Schlierentechnik.”https://doi.org/10.1515/teme-2023-0069__Tm - Technisches Messen 90, no.https://doi.org/10.1515/teme-2023-0069__(2023): 49–54.https://doi.org/10.1515/teme-2023-0069 .

Hetkämper, Tim. Visualisierung von Ultraschallfeldern Mittels Schlierentechnik Und Fraktionaler Fouriertransformation. Workshop “Messtechnische Anwendungen von Ultraschall”, Drübeck, 2022.

Hetkämper, Tim, Leander Claes, and Bernd Henning. “Schlieren Imaging with Fractional Fourier Transform to Visualise Ultrasonic Fields.” In Sensoren Und Messsysteme - Beiträge Der 21. ITG/GMA-Fachtagung. Berlin, Offenbach: VDE Verlag GmbH, 2022.

Claes, Leander, René Spencer Chatwell, Elmar Baumhögger, Tim Hetkämper, Henning Zeipert, Jadran Vrabec, and Bernd Henning. “Measurement Procedure for Acoustic Absorption and Bulk Viscosity of Liquids.”https://doi.org/10.1016/j.measurement.2021.109919__Measurement, 2021.https://doi.org/10.1016/j.measurement.2021.109919 .

Hetkämper, Tim, Dmitrij Dreiling, Leander Claes, and Bernd Henning. “Tomographie des Schallfelds von Ultraschallwandlern mittels Schlierentechnik.” In Fortschritte der Akustik - DAGA 2021, 2021.

Hetkämper, Tim, Matthias Krumme, Dmitrij Dreiling, and Leander 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, 1309–13. SEFI, 2020.

Claes, Leander, Carolin Steidl, Tim Hetkämper, and Bernd Henning. “Estimation of Acoustic Wave Non-Linearity in Ultrasonic Measurement Systems.”https://doi.org/10.48550/arXiv.2001.05708__ArXiv.Org, 2020.https://doi.org/10.48550/arXiv.2001.05708 .

Hetkämper, Tim, Leander Claes, and Bernd Henning. “Evolutionary Algorithm for the Design of Passive Electric Matching Networks for Ultrasonic Transducers.”https://doi.org/10.1121/2.0001110__In 2019 International Congress on Ultrasonics, 2019.https://doi.org/10.1121/2.0001110 .