Improvements of a high-speed focus distance modulated fibrecoupled confocal sensor for nanocoordinate measuring systems

Konferenz: Sensoren und Messsysteme - 19. ITG/GMA-Fachtagung
26.06.2018 - 27.06.2018 in Nürnberg, Deutschland

Tagungsband: ITG-Fb. 281: Sensoren und Messsysteme

Seiten: 4Sprache: EnglischTyp: PDF

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Groeschl, Andreas; Koehnen, Stephan; Schaude, Janik; Hausotte, Tino (Friedrich-Alexander-University Erlangen-Nuremberg FAU, Institute of Manufacturing Metrology, Germany)

This article presents improvements of a new robust, precise, high-frequency focal-distance-modulated confocal point sensor for probing in coordinate measuring systems (CMS). While maintaining the known advantages of the confocal measurement principle, the sensor represents an innovative combination of a fibre-coupled confocal illumination and detection with a tuneable, acoustically driven gradient-index fluid lens (TAG lens) for modulation of the focus distance and a novel signal processing utilizing a lock-in amplifier. The new arrangement is able to achieve an approximately linear characteristic curve for the optimised feedback control of the CMS in scanning sample mode. This article emphasises the improvement of the lock-in amplification by using a custom signal processing on the basis of a field programmable gate array (FPGA).