Multi-pulse laser beam generation method and device and laser beam

Abstract

A method and a device are provided for generating a multi-pulse laser beam including at least three laser beams, from a single pulse laser beam oscillated from a single laser beam source and a method and an apparatus using the pulse generator for laser beam machining with a two-wavelength multi-pulse laser beam suitable for fine-patterning a multi-layered circuit board formed of metal thin films and resin layers or ceramic bodies. One pulse laser beam from the laser beam source is separated into linear polarized laser beams in first and second directions by a polarization beam splitter, with the beam in the first direction being outputted as a first pulse beam of the multi-pulse beam. The beam in the second direction is incident to a combination of an optical fiber or a glass plate and a 1/4 wavelength plate, and is delayed and non-linearly polarized there to become a delayed and non-linearly polarized laser beam. The laser beam is again incident to the polarization beam splitter, where the delayed non-linearized pulse beam separated in the first direction is outputted as a second pulse beam of the multi-pulse laser beam. The delayed non-linearized pulse beam separated in the second direction is passed again through the above-described delay and non-linearization loop to generate a third pulse beam.