Microdrilling in Steel with Frequency-doubled Ultrashort Pulsed Laser Radiation

Abstract

In this paper we study the influence of the processing wavelength on process efficiency and quality at picosecond microdrilling in steel. Possible optical setups for utilizing the second harmonic will be presented, and the influence of wavelength on the drilling rate will be discussed. The potential of helical drilling with the second harmonic in 1 mm thick CrNi-steel will be investigated with regard to process efficiency and hole quality. An analysis will be given of the role of particle-ignited atmospheric plasma and the relation between isophote contour and hole morphology. Our study reveals that a substantial enhancement of both precision and productivity can be achieved by using frequency-doubled instead of infrared radiation. It is shown that plasma ablation and melt production can be minimized by drilling with the second harmonic.

Direct investigation of the ablation rate evolution during laser drilling of high aspect ratio micro-holes

“…For pulse duration down to a few picoseconds or even to some hundred femtoseconds, the laser ablation processes take place through phase explosion of a superheated melt layer with subsequent ejection of nano-sized particles and negligible thermal damage to the surrounding bulk material [2,3]. Besides the pulse duration, the laser fluence, the beam polarization, and the repetition rate are also relevant [4][5][6][7]. However, heat accumulation effects during pulsed laser irradiation at relatively high repetition rates (several hundred kHz) and pulse energies may still cause the generation of some amount of molten material, which is detrimental to the quality of the laser ablation [8][9][10].…”

Thermal lens compensation in high average power diode pumped Nd:YVO4laser using aspheric mirror

“…High average power picosecond lasers have been studied intensely because of their suitability for industrial applications such as laser micromachining [1][2][3], drilling precise holes for fuel injection [4], thin film patterning for solar cells [5].…”

Short-pulse lasers with the high power and repetition rate for microfabrication

“…Flexible and environment-friendly fabrication of variety engineering materials can be realized according to requirements of modern micro-and nanotechnologies. The technology is finding applications in drilling precise holes for fuel injection [1] or thin film patterning for solar cells [2]. Further realization of the opportunities in the real-world applications is tightly related with the progress in development of the diode-pumped solid-state (DPSS) lasers with short and ultra-short pulses.…”