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Automated discrimination of surface imperfections and adhered particles on customer-specific optical elements

  • Alexander Schöch

    Dr. Alexander Schöch received his BSc in computer engineering and his MSc in industrial engineering from the NTB where he worked on cryptoanalysis with FPGAs and highly parallelized software frameworks respectively. He received his PhD degree from the University of Padua for his work on the topic of metrology at elevated temperature and industrial process control. Currently, he is employed as a research associate at the Institute for Production Metrology, Materials and Technical Optics (PWO) of NTB. His interests include computer graphics, computer vision and machine learning technology.

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    , Patric Perez

    Patric Perez received a BSc in systems engineering with specialisation in computer engineering from the NTB. He created an interactive android teaching game for electrostatics and magnetism on bachelor level. Since his graduation he is employed at the Institute for Production Metrology, Materials and Technical Optics (PWO) of NTB as research associate. His main activities are planning and realisation of machine vision setups and subsequent image processing as applied research.

    , Sabine Linz-Dittrich

    Sabine Linz-Dittrich completed an apprenticeship as an optician at the company Zeiss in Jena. Afterwards she studied Optical Hardware and Spectroscopy Engineering at the institute LITMO in St. Peterbursburg, Russia. She completed her physics diploma thesis at the TU Berlin with the focus on thin film solar cells. During eleven years she was employed at Balzers Optics in Liechtenstein, there she gained experience as a development engineer in optical coatings as well as leading a production line of optical components. Since 2010 she is employed as a research associate at the Institute for Production Metrology, Materials and Technical Optics (PWO) of NTB.

    , Carlo Bach

    Prof. Dr. Carlo Bach received his diploma and his PhD in computer science from ETH Zurich. After several years in industry working in the field of artificial intelligence he joined the university of applied sciences NTB where he teaches computer science and image processing courses. Mr. Bach leads the machine vision group of the Institute for Production Metrology, Materials and Technical Optics (PWO). He is interested in all kinds of surface inspection with 2D and 3D methods.

    and Carsten Ziolek

    Carsten Ziolek finished his studies in physics at the University of Hanover in 1997 with a work on wavelength selection and Q-switching of erbium lasers. During his doctorate at the Laser Centre Hanover he worked on the laser dynamics of these systems. He earned his PhD in 2000 with a work on particular Erbium-based infrared-lasers for ophthalmology applications. From 2001 until 2015 he worked for the company TRUMPF in different positions, finally for more than 10 years as Head R&D of TRUMPF’s marking lasers. In 2015 he was appointed as professor at the NTB. There he leads the Institute for Production Metrology, Materials and Optics as well as its technical optics and photonics field of competence. Carsten Ziolek is author of multiple technical publications and talks and is also involved in numerous patents.

Published/Copyright: June 8, 2019

Abstract

In previous work, we proposed an automated system, capable of detecting surface defects (e. g. edge chips, digs, scratches) on optical components as defined in the international standard ISO 10110-7. It objectively discriminates between defect classes and quantifies their geometrical size. During assessment of quality control at multiple manufacturers, the need for a method to discriminate between dust particles and surface imperfections has been identified. This article describes an approach to automatically assess dust particles and imperfections on the surface of interest based on the stereo vision approach.

Zusammenfassung

In früheren Arbeiten haben wir ein automatisiertes System vorgestellt, das in der Lage ist, Oberflächeunvollkommenheiten (z. B. Randaussprünge, Löcher, Kratzer) an optischen Komponenten zu erkennen, wie sie in der Norm ISO 10110-7 definiert sind. Das System unterscheidet objektiv zwischen Fehlerklassen und quantifiziert deren geometrische Größe. Während der Bewertung der Qualitätskontrolle von mehreren Herstellern hat sich die Notwendigkeit für eine Methode zur Unterscheidung von Staubpartikeln und Oberflächenfehlern herausgestellt. Dieser Artikel beschreibt einen Stereo basierten Ansatz zur automatischen Unterscheidung zwischen Staubpartikeln und Unvollkommenheiten auf zu prüfenden Oberfläche.

Funding statement: This work was supported by Innosuisse (KTI 18084.1 PFNM-NM: SurfInspect: Automatisierte Oberflächeninspektion von planen und sphärischen optischen Komponenten).

About the authors

Dr. Alexander Schöch

Dr. Alexander Schöch received his BSc in computer engineering and his MSc in industrial engineering from the NTB where he worked on cryptoanalysis with FPGAs and highly parallelized software frameworks respectively. He received his PhD degree from the University of Padua for his work on the topic of metrology at elevated temperature and industrial process control. Currently, he is employed as a research associate at the Institute for Production Metrology, Materials and Technical Optics (PWO) of NTB. His interests include computer graphics, computer vision and machine learning technology.

BSc. Patric Perez

Patric Perez received a BSc in systems engineering with specialisation in computer engineering from the NTB. He created an interactive android teaching game for electrostatics and magnetism on bachelor level. Since his graduation he is employed at the Institute for Production Metrology, Materials and Technical Optics (PWO) of NTB as research associate. His main activities are planning and realisation of machine vision setups and subsequent image processing as applied research.

Dipl.-Phys. Sabine Linz-Dittrich

Sabine Linz-Dittrich completed an apprenticeship as an optician at the company Zeiss in Jena. Afterwards she studied Optical Hardware and Spectroscopy Engineering at the institute LITMO in St. Peterbursburg, Russia. She completed her physics diploma thesis at the TU Berlin with the focus on thin film solar cells. During eleven years she was employed at Balzers Optics in Liechtenstein, there she gained experience as a development engineer in optical coatings as well as leading a production line of optical components. Since 2010 she is employed as a research associate at the Institute for Production Metrology, Materials and Technical Optics (PWO) of NTB.

Prof. Dr. Carlo Bach

Prof. Dr. Carlo Bach received his diploma and his PhD in computer science from ETH Zurich. After several years in industry working in the field of artificial intelligence he joined the university of applied sciences NTB where he teaches computer science and image processing courses. Mr. Bach leads the machine vision group of the Institute for Production Metrology, Materials and Technical Optics (PWO). He is interested in all kinds of surface inspection with 2D and 3D methods.

Prof. Dr. Carsten Ziolek

Carsten Ziolek finished his studies in physics at the University of Hanover in 1997 with a work on wavelength selection and Q-switching of erbium lasers. During his doctorate at the Laser Centre Hanover he worked on the laser dynamics of these systems. He earned his PhD in 2000 with a work on particular Erbium-based infrared-lasers for ophthalmology applications. From 2001 until 2015 he worked for the company TRUMPF in different positions, finally for more than 10 years as Head R&D of TRUMPF’s marking lasers. In 2015 he was appointed as professor at the NTB. There he leads the Institute for Production Metrology, Materials and Optics as well as its technical optics and photonics field of competence. Carsten Ziolek is author of multiple technical publications and talks and is also involved in numerous patents.

References

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Received: 2019-02-28
Accepted: 2019-05-30
Published Online: 2019-06-08
Published in Print: 2019-07-26

© 2019 Walter de Gruyter GmbH, Berlin/Boston

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