We describe a focus control system for Nd:YAG laser welding based on an optical sensor incorporated into the fiber delivery system to detect light generated by the process. This broadband light is separated into two wavelength bands, and simple electronic processing gives a signal proportional to focal error as a result of chromatic aberrations in the optical delivery system. Focus control is demonstrated for bead-on-plate welds in different thicknesses of titanium alloy, aluminum alloy, mild steel, and stainless steel. The control system works for both pulsed and continuous laser radiation.
© 1997 Optical Society of America
Original Manuscript: October 30, 1996
Published: July 20, 1997
Francis M. Haran, Duncan P. Hand, Chris Peters, and Julian D. C. Jones, "Focus control system for laser welding," Appl. Opt. 36, 5246-5251 (1997)