METHOD OF AND MATERIAL PROCESSING APPARATUS FOR OPTIMISING THE FOCUS OF A FIBRE LASER; METHOD OF MEASURING CHANGES IN THE FOCUS OF A FIBRE LASER

摘要

A method of optimising the focus of a fibre laser is described, which comprises positioning the output of a fibre laser relative to a workpiece; measuring at least a portion of back reflected radiation from the workpiece (step 52); determining an integral of this; changing the relative position of the output and the workpiece one or more times (step 54,56), each time determining an integral of values for the back-reflection, and using the integrals to determine optimum focus.