Patent ID: 9233434
Filing Date: 2016-01-12
CPC Classification: B23K

Claim Text:
1. A method of optimising the focus of a fibre laser, comprising positioning the output of a fibre laser relative to a workpiece; generating pulses of laser radiation; measuring at least a portion of a waveform of back reflected radiation from the workpiece resulting from the pulses; changing the relative position of the output and the workpiece a plurality of times; generating pulses of laser radiation and measuring at least a portion of a waveform of back reflected radiation from the workpiece resulting from the pulses each time; and analysing, by a processor, the resulting measured back-reflected radiation to determine optimum focus, wherein the power of the pulses is selected so that a phase change occurs at the workpiece and wherein the analysing the resulting measured back-reflected radiation comprises determining integrals of the back reflected radiation at each relative position and using the integrals to determine optimum focus by determining a minimum value of the integrals.