Inline Coherent Imaging of Laser Keyhole Welding
Loading...
Authors
Galbraith, Christopher Mark
Date
2015-05-01
Type
thesis
Language
eng
Keyword
Inline Coherent Imaging , Laser Process Monitoring , Laser Keyhole Welding , Laser Materials Processing
Alternative Title
Abstract
Laser keyhole welding is an emerging materials processing technique offering many advantages over more conventional joining methods. High intensity laser light is applied to a sample, melting and evaporating the metal in its path. The resulting recoil pressure drives a narrow capillary (a 'keyhole') of vapour into the metal, allowing delivery of laser energy deep beneath the surface. The resulting weld seams are deep, narrow, precisely positioned, and often require no filler material. However, the process is inherently unstable and its underlying physics are not straightforward. The keyhole has traditionally proven difficult to measure, which hinders efforts to model, understand, and control this process. Inline coherent imaging (ICI), a laser-based ranging technique, has previously been demonstrated as an effective tool for in-situ measurement of the keyhole depth. In this work, I seek to improve our understanding of ICI's measurement of the keyhole, and enhance its utility. A new algorithm that tracks keyhole depth with zero resolution loss is demonstrated. Mechanisms responsible for signal losses in the weld image are explored, and a modified ICI system producing doubled line-rates near 600 kHz is realized. Active imaging beam scanning is implemented, increasing the resolving capability of the ICI system to three spatial dimensions. With this new capability, I measure keyhole morphology in-situ--an entirely novel way of observing this elusive and volatile physical system.
Description
Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2015-04-30 16:01:35.23
Citation
Publisher
License
Queen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canada
ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.