Patent ID: 6188041
Filing Date: 2001-02-13
Classification: B23K

Abstract:
A method for real-time monitoring a weld pool size, a weld depth and a weld gap in a pulsed laser welding, the method comprising the steps of:transmitting a plurality of laser pulses through an aperture which limits a size of a pulsed laser beam;focusing transmitted laser pulses with at least one lens with large chromatic aberration but minimum spherical aberration on a workpiece;sensing a thermal radiation from a weld pool through said at least one lens, and through said aperture;separating the thermal radiation and the laser pulses with a dichromatic mirror;splitting the thermal radiation with a dichromatic beam splitter into two spectral bands;filtering each spectral band of the thermal radiation with a narrow band-pass optical filter;detecting each narrow band-pass filtered thermal radiation with a detector during the laser pulses and between the laser pulses;sampling electrical signals as detector signals from said detectors digitally for each laser pulse;processing said two detector signals as processed signals; andanalyzing the processed signals for real-time monitoring of the weld pool size, the weld depth and the weld gap.