Imaging Diagnostics of Debris from Laser-Produced Tin Plasma with Droplet Target for EUV Light Source

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.

Analysis of atomic and ion debris features of laser-produced Sn and Li plasmas

“…Little effort has been spent on understanding the evolution of the fast neutrals from Sn and Li plasmas. Typical diagnostic tools employed for understanding the evolution of neutrals in a plume are laser-induced fluorescence 38 and optical TOF ͑OTOF͒emission spectroscopy. 39,40 OES is one of the simplest, nonintrusive ways to investigate early plasma dynamics, since it uses the intrinsic light emission from the LPP, and does not require external excitation.…”