PULSED LASER MACHINING METHOD AND INSTALLATION, PARTICULARLY FOR WELDING, WITH VARIATION OF THE POWER OF EACH LASER PULSE

摘要

The laser machining method involves the following steps: A) using a laser source to generate a laser beam at an initial wavelength of between 700 and 1200 nanometers and formed of a succession of laser pulses (10); B) doubling the frequency of part (12) of the laser beam using a non-linear crystal; C) varying the power during each emitted laser pulse (10) so that the power profile over the period of this laser pulse has, in an initial sub-period (T1), a maximum power peak or a pulse part with a maximum power and, in an intermediate sub-period (T2), of duration longer than the initial sub-period, a power lower than said maximum power over all of this intermediate sub-period. The power of the laser is varied in such a way that the maximum power has a value at least twice as high as the mean power over the period of the laser pulse and that the rise time taken to increase to a maximum power from the start of each laser pulse is shorter than 0.3 milliseconds. The machining method relates in particular to the welding of highly reflective metals such as copper, gold, silver or an alloy containing one of these metals. The intention also relates to a laser machining installation for implementing the method described hereinabove.