Prozessüberwachung beim Laserreinigen und Laserschichtabtrag durch Anwendung der Plasmaanalyse mittels "low resolution" Spektrometer

Bei der Laserreinigung und dem Laserabtrag an Mehrschichtsystemen ist es von großer Bedeutung, eine Be-schädigung der zu erhaltenden Schicht zu vermeiden. Ein Verfahren zur Überwachung des Laserabtragsprozes-ses ist die "Laser Induzierte Plasma Spektroskopie" (LIPS) [1,2,3,4]. Unterschiede im Schichtaufbau bewirken Veränderungen im Spektrum und der Intensität des Plasmas. Ein Nachteil gebräuchlicher LIPS-Systeme sind die hohen Investitionskosten und die komplexe Handhabung. Neueste Entwicklungen in der Spektrometer-Technologie bieten inzwischen sehr kompakte Systeme mit einfacher Handhabung und niedrigen Investitions-kosten [5,6]. Im Laserzentrum der FH Münster wurde ein "low cost"-LIPS-System zur Laserreinigung/-abtrag in einem Excimer-Laser und Nd:YAG-Laser (mit Frequenzvervielfachung) integriert, um den Abtragprozess zu ü-berwachen und ggf. zu regeln. Die Schichterkennung funktioniert über lineare Korrelation mit vorher aufge-nommenem Referenzspektrum [7,8,9]. Wenn der Korrelationskoeffizient sich einem vorher festgelegten Wert nähert, wird der Abtrags-/Reinigungsprozess gestoppt. Erste Tests haben positive Ergebnisse gezeigt und werden zusammen mit dem Verfahren in diesem Artikel beschrieben

A diagnostic tool for German syntax

In this paper we describe an effort to construct a catalogue of syntactic data, exemplifying the major syntactic patterns of German. The purpose of the corpus is to support the diagnosis of errors in the syntactic components of natural language processing (NLP) systems. Two secondary aims are the evaluation of NLP systems components and the support of theoretical and empirical work on German syntax. The data consist of artificially and systematically constructed expressions, including also negative (ungrammatical) examples. The data are organized into a relational data base and annotated with some basic information about the phenomena illustrated and the internal structure of the sample sentences. The organization of the data supports selected systematic testing of specific areas of syntax, but also serves the purpose of a linguistic data base. The paper first gives some general motivation for the necessity of syntactic precision in some areas of NLP and discusses the potential contribution of a syntactic data base to the field of component evaluation. The second part of the paper describes the set up and control methods applied in the construction of the sentence suite and annotations to the examples. We illustrate the approach with the example of verbal government. The section also contains a description of the abstract data model, the design of the data base and the query language used to access the data. The final sections compare our work to existing approaches and sketch some future extensions. We invite other research groups to participate in our effort, so that the diagnostics tool can eventually become public domain

Seeing Around Street Corners: Non-Line-of-Sight Detection and Tracking In-the-Wild Using Doppler Radar

Conventional sensor systems record information about directly visible objects, whereas occluded scene components are considered lost in the measurement process. Non-line-of-sight (NLOS) methods try to recover such hidden objects from their indirect reflections - faint signal components, traditionally treated as measurement noise. Existing NLOS approaches struggle to record these low-signal components outside the lab, and do not scale to large-scale outdoor scenes and high-speed motion, typical in automotive scenarios. In particular, optical NLOS capture is fundamentally limited by the quartic intensity falloff of diffuse indirect reflections. In this work, we depart from visible-wavelength approaches and demonstrate detection, classification, and tracking of hidden objects in large-scale dynamic environments using Doppler radars that can be manufactured at low-cost in series production. To untangle noisy indirect and direct reflections, we learn from temporal sequences of Doppler velocity and position measurements, which we fuse in a joint NLOS detection and tracking network over time. We validate the approach on in-the-wild automotive scenes, including sequences of parked cars or house facades as relay surfaces, and demonstrate low-cost, real-time NLOS in dynamic automotive environments.Comment: First three authors contributed equally; Accepted at CVPR 202

5th International Conference LACONA V (Lasers in the Conservation of Artworks)

Since 1995, when Costas Fotakis first brought together restorers and scientists to discuss the potential of lasers in art conservation, the field has grown enormously in importance, and today restorers and laser scientists work together to develop new applications. This book presents the more than six dozen research papers prepared for LACONA V (Lasers in Art Conservation), held in Osnabrueck/Germany in September 2003. The fifth congress once again gathers restorers, art historians, museum staff, laser scientists and laser manufacturers. The topics include, among others: laser cleaning of artworks (case studies and side effects), removal of former conservation layers, fundamentals of laser-artwork interaction, online monitoring and process control, laser diagnostics, spectroscopy for monitoring and identification, networks and co-operation projects