CONTROLLED LASER CLEANING AND ABLATIONBY LASER INDUCED PLASMA EMISSION ANALYSIS VIA MINIATURE SPECTROMETER

摘要

A disadvantage of common LIBS systems is the high investment cost, ambience sensitivityrnand complexity. Recent developments in spectrometer technology have resulted in ruggedrnLIBS systems with reduced cost, size and complexity [1,2]. Furthermore these novel systemsrnare user friendly. Thus LIBS has gained increasingly importance for practical applications in online monitoring during laser cleaning and ablation. We have arranged a low cost LIBSrnsetup with a miniature fibre optic spectrometer. It can measure a wide spectral range at lowrnlambda resolution in a single shot. The plasma radiation is coupled into a 600 μm glass fibrernby a collimator positioned above the irradiated sample in order to gather a part of the plasmarnradiation. The sensitiveness and λ-resolution of this system is not as high as for conventionalrnLIBS systems used for elemental notification. However, it was found out that for controlling arnlaser cleaning or ablation process detailed elemental notification is not necessary [3]. Layerrnrecognition via measured low resolution spectra can be done by a fingerprint method. Reliablernlayer identification with this fingerprint method is also possible in the first part of the plasmarnignition. This is characterized by a strong intensity and a broadband emission where somernionic emission lines of the plume constituents arise.