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Master's Thesis
Author of thesis: Ing. Josef Hrdlička
Acad. year: 2024/2025
Supervisor: Ing. Jakub Buday, Ph.D.
Reviewer: Mgr. Aleš Hrdlička, Ph.D., Ph.D.
This diploma thesis reports the development and demonstration of a Mach–Zehnder interferometer integrated into a Laser-Induced Breakdown Spectroscopy (LIBS) setup to measure time and spatially resolved electron density and shock-wave dynamics in laser-induced plasmas. A novel, near-infrared Ho:YAG laser at 2090 nm (4 ns pulses, 3.65 mJ) was compared to a conventional Nd:YAG source at 1064 nm (5 ns, 23 mJ) across steel samples of varying hardness (H0–H6) and copper. Measurements were done under standard laboratory conditions. To produce stable interference fringes over extended periods, optical components were mounted in a rigid cage system design, minimizing mechanical drift. A semi-automated Python-based processing script was created to handle the vast interferogram dataset, performing image cropping, Fourier-transform phase extraction, Abel inversion, electron density calculation, and plasma segmentation in seconds per frame. Key findings include higher plasma electron densities and more distinct shockwave fringes for 1064 nm excitation, attributable to its greater photon energy. A clear correlation between sample hardness and electron density, with copper exhibiting the lowest values. These results validate the Mach–Zehnder approach for quantitative plasma diagnostics and introduce the 2090 nm pump laser as a promising new wavelength for LIBS, particularly when combined with automated image analysis for high-throughput data processing.
LIBS, laser-indeced plasma, plasma, ablation, abel transform, electron density, atomic spectra, Mach-Zehnder Interferometer, image processing.
Date of defence
10.06.2025
Result of the defence
Defended (thesis was successfully defended)
Grading
B
Process of defence
Po otázkách oponenta bylo dále diskutováno: Povrchová citlivost techniky. Princip rozšíření laserového svazku. Student na otázky odpověděl.
Language of thesis
English
Faculty
Fakulta strojního inženýrství
Department
Institute of Physical Engineering
Study programme
Physical Engineering and Nanotechnology (N-FIN-P)
Composition of Committee
prof. RNDr. Tomáš Šikola, CSc. (předseda) prof. RNDr. Jiří Spousta, Ph.D. (místopředseda) prof. RNDr. Pavel Zemánek, Ph.D. (člen) prof. Mgr. Dominik Munzar, Dr. (člen) doc. Mgr. Adam Dubroka, Ph.D. (člen) prof. RNDr. Petr Dub, CSc. (člen) prof. Ing. Jan Čechal, Ph.D. (člen) prof. RNDr. Jiří Petráček, Dr. (člen) prof. RNDr. Radim Chmelík, Ph.D. (člen) doc. Ing. Radek Kalousek, Ph.D. (člen) prof. Ing. Miroslav Kolíbal, Ph.D. (člen) doc. Ing. Stanislav Průša, Ph.D. (člen) doc. Mgr. Vlastimil Křápek, Ph.D. (člen) RNDr. Antonín Fejfar, CSc. (člen)
Supervisor’s reportIng. Jakub Buday, Ph.D.
Grade proposed by supervisor: A
Reviewer’s reportMgr. Aleš Hrdlička, Ph.D., Ph.D.
Grade proposed by reviewer: B
Responsibility: Mgr. et Mgr. Hana Odstrčilová