Exploiting the whole information content of the light field: Limitations and approaches

  • Wolfgang Osten University of Stuttgart
Keywords: Optics, Metrology


In the context of measurement technology, optical methods have a number of unique features. To them belong in particular the non-contact and high speed interaction with the object under test, the largely free scalability of the dimension of the probing tool, the high resolution of the data, the diversity of information channels in the light field, and the flexible adaptability of the comparative standard. On the other hand, the user is also confronted with a bunch of challenges. Here one should mention especially the indirect nature of the measurement. This fact is the origin of a number of serious consequences which make it often difficult for the practitioner to decide for optical metrology. However, the numerous information channels recommend optical principles for the solution of various inspection and measurement problems. A broad variety of techniques is sensitive for the measurement of a particular quantity such as the intensity, the frequency, the phase, the angular spectrum, the polarization state, the angular momentum, the degree of coherence and the time of flight. By applying these methods a wide spectra of quantities can be evaluated. To them belong dimensional, structural, geometrical, colorimetrical, chemical, and mechanical properties of the object under test. More modern principles such as hyper-spectral technologies are designed to measure various modalities with one system. Known under the name of multimodal measurement techniques, these systems are capable of elegantly solving complex medical, structural-mechanical or biological problems. However, the high information density in optical signals is often not only an advantage but a challenge with respect to the correct interpretation of the measured data. This talk starts with a brief summary of the advantages and disadvantages of optical metrology. Afterwards we discuss the various information channels and present examples for their exploitation. Special attention is directed to the correct interpretation of the data.

About the Speaker

Wolfgang Osten received the MSc/Diploma in Physics from the Friedrich-Schiller University Jena in 1979. From 1979 to 1984 he was a member of the Institute of Mechanics in Berlin working in the field of experimental stress analysis and optical metrology. In 1983 he received the PhD degree from the Martin-Luther University Halle-Wittenberg for his thesis in the field of holographic interferometry. From 1984 to 1991 he was employed at the Central Institute of Cybernetics and Information Processes ZKI in Berlin making investigations in digital image processing and computer vision. Between 1988 and 1991 he was heading the Institute for Digital Image Processing at the ZKI. In 1991 he joined the Bremen Institute of Applied Beam Technology (BIAS) to establish and to direct the Department Optical 3D-Metrology till 2002. Since September 2002 he has been a full professor at the University of Stuttgart and director of the Institute for Applied Optics. From 2006 till 2010 he was the vice rector for research and technology transfer of the University of Stuttgart where he is currently the vice chair of the university council. His research work is focused on new concepts for industrial inspection and metrology by combining modern principles of optical metrology, sensor technology and image processing. Special attention is directed to the development of resolution enhanced technologies for the investigation of micro and nanostructures.