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Diego-Vallejo D.,TU Berlin | Diego-Vallejo D.,National Polytechnic Institute of Mexico | Schwagmeier M.,Laser und Medizin Technology Berlin GmbH LMTB | Ashkenasi D.,Laser und Medizin Technology Berlin GmbH LMTB | And 3 more authors.
Journal of Laser Micro Nanoengineering | Year: 2011

Laser-induced breakdown spectroscopy (LIBS), a versatile analytical tool to determine sample compositions, has recently been applied to monitor and control laser material processing. By observing the induced plasma during laser machining, an insight of the current processing stage can be gained. The aim of this project is to use the already present plasma in laser material processing to improve the quality of the product by means of spectroscopic analysis. Experimental studies have been carried out looking for useful correlations between material processing parameters and spectroscopic plasma signal. The presence of such characteristic patterns in the spectral data can be uti-lized to implement a control strategy to monitor the process. Source


Diego-Vallejo D.,TU Berlin | Diego-Vallejo D.,Laser und Medizin Technology Berlin GmbH LMTB | Ashkenasi D.,Laser und Medizin Technology Berlin GmbH LMTB | Lemke A.,Laser und Medizin Technology Berlin GmbH LMTB | And 2 more authors.
Spectrochimica Acta - Part B Atomic Spectroscopy | Year: 2013

Laser-induced breakdown spectroscopy (LIBS) and two classification methods, i.e. linear correlation and artificial neural networks (ANN), are used to monitor P1, P2 and P3 scribing steps of Copper-Indium-Diselenide (CIS) solar cells. Narrow channels featuring complete removal of desired layers with minimum damage on the underlying film are expected to enhance efficiency of solar cells. The monitoring technique is intended to determine that enough material has been removed to reach the desired layer based on the analysis of plasma emission acquired during multiple pass laser scribing. When successful selective scribing is achieved, a high degree of similarity between test and reference spectra has to be identified by classification methods in order to stop the scribing procedure and avoid damaging the bottom layer. Performance of linear correlation and artificial neural networks is compared and evaluated for two spectral bandwidths. By using experimentally determined combinations of classifier and analyzed spectral band for each step, classification performance achieves errors of 7, 1 and 4% for steps P1, P2 and P3, respectively. The feasibility of using plasma emission for the supervision of processing steps of solar cell manufacturing is demonstrated. This method has the potential to be implemented as an online monitoring procedure assisting the production of solar cells. © 2013 Elsevier B.V. All rights reserved. Source


Ashkenasi D.,Laser und Medizin Technology Berlin GmbH LMTB | Mueller N.,Laser und Medizin Technology Berlin GmbH LMTB | Kaszemeikat T.,Laser und Medizin Technology Berlin GmbH LMTB | Illing G.,Laser und Medizin Technology Berlin GmbH LMTB
Journal of Laser Micro Nanoengineering | Year: 2011

The LMTB has designed and implemented a novel optical concept for the development of a ver-satile trepanning system, enabling the adjustment of the displacement and the inclination angle dur-ing circular rotation at up to 20000 r.p.m. The presented trepanning systems are able to laser ma-chine through-holes diameters of 100 μm with a negative taper of up to 5°. Starting from an early stage of implementation, the novel trepanning system has been customized for different applications and industrial partners. The conference paper outlines the development steps and advanced per-formance, accenting laser micro machining results utilizing the novel LMTB trepanning system in operation at different laser parameters. Source

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