Laser Micro Drilling Using a Nanosecond-Pulse Bessel Beam

The feasibility was examined of using a Bessel beam (J0 beam) for laser micro drilling. A J0 beam, generated using a nanosecond pulse laser and an Axicon, was used to drill into 20 μm-thick SUS304 stainless steel foil. The fairly precise columnar penetration holes were about 3 μm in diameter, with an aspect ratio of approximately 7. A J0 beam can be used to process both transparent and opaque materials. The major problems of the present laser micro drill will be solved by using a J0 beam. It is thought that the excellent characteristics of laser drill using a J0 beam is given by the extremely deep focal depth a J0 beam has.