Enhanced depth of field laser processing using an ultra-high-speed axial scanner

Lasers are ubiquitous in materials processing, but the requirement of precise control of the focal plane in order to ensure optimal performance constitutes a time limiting step for high-throughput laser manufacturing. Here, we overcome this limitation by axially scanning the focus at high speeds using an acoustically driven liquid lens. We demonstrate this approach by processing silicon surfaces, and we find it is possible to enhance the depth-of-field by an order of magnitude without loss in lateral resolution. These results open the door to a fundamental change in the paradigm for laser processing by eliminating the need in z-focus control.