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Proceedings Paper

Auto-focus control and weld process monitoring of laser welding using chromatic filtering of thermal radiation
Author(s): Cheol-Jung Kim; Sung-Hoon Baik; Min Seok Kim; Chin-Man Chung
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Paper Abstract

The thermal radiation from a weld pool is focused on an aperture and the transmitted thermal radiation is monitored at two wavelengths with high-speed single-element detectors. Due to the chromatic aberration introduced in the focusing optics, the transmittance curve of thermal radiation varies by the wavelength. Likewise, the detector field of view varies by the wavelength. Owing to this difference in the transmittance and in the field of view, the local variation in a weld pool can be monitored by processing the two spectroscopic signals from two detectors. In this paper, the algorithms to monitor the weld pool size and the focus shift are presented and the performances of weld pool size monitoring and auto-focus control are shown for a pulsed Nd:YAG laser welding. The size variation monitoring has been applied to the weld depth and weld defects monitoring. The effects of laser power change and weld defects on the weld pool size variation are also shown.

Paper Details

Date Published: 15 August 1998
PDF: 11 pages
Proc. SPIE 3550, Laser Processing of Materials and Industrial Applications II, (15 August 1998); doi: 10.1117/12.317954
Show Author Affiliations
Cheol-Jung Kim, Korea Atomic Energy Research Institute (South Korea)
Sung-Hoon Baik, Korea Atomic Energy Research Institute (South Korea)
Min Seok Kim, Korea Atomic Energy Research Institute (South Korea)
Chin-Man Chung, Korea Atomic Energy Research Institute (South Korea)


Published in SPIE Proceedings Vol. 3550:
Laser Processing of Materials and Industrial Applications II
ShuShen Deng; S. C. Wang, Editor(s)

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