Mikrooptische Sensoren nach dem chromatisch konfokalen Messprinzip

Peter Lücke, Arndt Last, Jürgen Mohr
Reliable and near process measurements of high precision components with sub micrometer tolerances are becoming increasingly important in modern production metrology. Especially measuring tasks of parts difficult to access, for example form and surface measurements of deep drilled holes with small diameters place high demands on today's tactile and optical measurement systems and can not be solved completely. This work focuses on the development of miniaturized straight and perpendicular
more » ... erpendicular measuring distance sensors, suitable for near process monitoring tight tolerances of small optical and mechanical high precision parts. The chromatic confocal principle was selected, which is based on a chromatic coding of the distance information. Compared to tactile measurement techniques this optical principle allows faster and contactless object scanning. In regard to other optical measurement techniques this optical principle features longitudinal resolution in the nanometer scale, large numerical apertures and small measurement spot diameters. Chromatic confocal sensors consist of three main elements: a light source, a sensor head and a spectral detection unit. After evaluation, fibre coupled superluminescent diodes were selected as light sources. For the following integration of the sensor systems in coordinate measurement systems a specially adapted LIGA micro spectrometer was developed. This spectrometer enables high measurement accuracies and measurement rates up to 1 kHz. The central task of this work was the development of perpendicular and straight measuring sensor heads. Miniaturization of the sensor heads succeeded in combining refractive and diffractive micro optical elements. Additionally, LIGA-technology was used to experimentally verify a range of free-space and integrated optical design concepts. An integrated optical design based on gradient index lenses proved to be the most suitable for miniaturized chromatic confocal sensors. A perpendicular measuring sensor head with a diameter of 1.2 mm and a straight measuring sensor with an outside diameter of 2.8 mm were fabricated. Within the characterization of the entire sensor system height resolutions of about 20 nm of the perpendicular measuring and 10 nm of the straight measuring sensor head have been demonstrated. This work was supported by the German Bundesministerium für Bildung und Forschung (BMBF), project number OD2001-038 "Hybride microoptical sensors (HymoSens) ". The Institute of Applied Optics (ITO) of the University of Stuttgart and the companies Mahr GmbH, Göttingen and Boehringer Ingelheim microParts GmbH, Dortmund participated in this joint research project. iii VORWORT Die vorliegende Arbeit entstand während meiner Tätigkeit im Institut für Mikrostrukturtechnik (IMT) am Forschungszentrum Karlsruhe (FZK) im Rahmen des vom Bundesministerium für Bildung und Forschung (BMBF) geförderten Verbundprojekts HymoSens. Ich möchte mich bei allen bedanken, die mir diese Doktorarbeit ermöglicht haben: Meinem Doktorvater Herrn Prof. Dr. Volker Saile, der mich bereits im Studium bei meiner Diplomarbeit an der University of Washington in Seattle unterstützte, danke ich ganz herzlich für seine Förderung meiner Arbeit und für die Übernahme des Hauptreferats. Bei Herrn Prof. Dr. Hans Zappe bedanke ich mich ebenfalls ganz herzlich für das Interesse an dieser Arbeit und die Übernahme des Korreferats.
doi:10.5445/ir/1000004651 fatcat:efpd4es44fcnhoygblhgbkxece