Picosecond lasers in micromachining

Abstract

Recent improvements to mode-locked lasers with picosecond pulse duration have fueled an increased interest for industrial applications, especially micromachining. Short pulses offer advantages for ablation of various materials. Reduced thermal load, low ablation threshold and other advantages of shorter pulses need to be tested for real application.PL2200 series all-solid-state lasers made by Ekspla Ltd. Have been tested and the results reported. Active mode-locking enables stable operation of the lasers. High peak-power permits efficient conversion to UV. Pulse duration less than 60 ps, pulse energy of several milijoules and 1 kHz repetition rate offer a wide range of energy density above the threshold for processing.Ablation rate and threshold were tested in processing of Teflon, PMMA, diamond and silicon for fundamental and harmonic radiation from the laser. Grooves, holes, and geometric shapes were cut in materials at various feed speeds. Samples were visually inspected for crack formation near cutting edges, deposit of recast material, and surface quality.Demonstration of the advantages of picosecond laser pulses in machining requires understanding of the interactions of material with laser radiation. Improvements are evident in machining of diamond and silicon, while for Teflon even UV radiation provides unacceptable results.Recent improvements to mode-locked lasers with picosecond pulse duration have fueled an increased interest for industrial applications, especially micromachining. Short pulses offer advantages for ablation of various materials. Reduced thermal load, low ablation threshold and other advantages of shorter pulses need to be tested for real application.PL2200 series all-solid-state lasers made by Ekspla Ltd. Have been tested and the results reported. Active mode-locking enables stable operation of the lasers. High peak-power permits efficient conversion to UV. Pulse duration less than 60 ps, pulse energy of several milijoules and 1 kHz repetition rate offer a wide range of energy density above the threshold for processing.Ablation rate and threshold were tested in processing of Teflon, PMMA, diamond and silicon for fundamental and harmonic radiation from the laser. Grooves, holes, and geometric shapes were cut in materials at various feed speeds. Samples were visually inspected for crack formation near cuttin...