Investigation of micro lens multi spot generator for parallel micromachining of silicon with picosecond and nanosecond laser

Abstract

Multi spot optics are used for parallelizing production and therefore enabling large-scale material processing. These elements split the beam into a periodic spot pattern with a defined grid and spot size. The challenge lies in the generation of a homogeneous envelope. Micro lens arrays offer a high flexibility in dimensions and shapes for the generation of different multi spot patterns. Within the paper we present the investigation of a micro lens array in a fly's eye condenser setup for the generation of homogeneous spot patterns. The principal functionality of the multi spot generator is shown and constraints of this setup are demonstrated. The multi spot generator is used for micro structuring of silicon with a nanosecond and a picosecond laser both at a wavelength of 355 nm. The multi spot generator splits the incoming beam into a linear spot matrix with 28 single spots. The ablation rate and structure quality using a multi spot generator are investigated compared to conventional treatment. It can be shown, that both ablation efficiency and structure quality can be increased by using a multi spot generator.