Concept and operating performance of inspection machines for industrial use based on laser-induced breakdown spectroscopy

In the last years laser-induced breakdown spectroscopy was introduced in various industrial applications. Automated inspection machines were developed capable to operate under harsh ambient conditions. As an example laser-induced breakdown spectroscopy-based inspection machines for the identification testing of fittings and tubes made of high-alloy steel will be presented. Within an inspection time of 2 seconds 100 spectra are gained yielding the signals of 12 elemental lines to identify more than 30 different high-alloy steel grades in order to prevent material mix-ups at the end of a production line prior to packaging and dispatch. More than 1.5 million products have been inspected within the last 5 years in routine operation. Requirements, concepts and design of such machines will be discussed considering the issues on analytical resolution and system monitoring. For the first time a data set of more than 108 laser-induced breakdown spectroscopy measurements has become available, giving insight into the long-term behavior of the system performance. First evaluations of this data demonstrate the influence of laser power, sample position and temperature on the spectroscopic signals and the system state. Future demands on next-generation inspection machines based on laser-induced breakdown spectroscopy will be defined.