In order to investigate deterioration processes in the paint layers on the famous 2000-yr-old Chinese Terracotta warriors, a low coherence ESPI system was designed. In this modified set-up a short-coherent superluminescence diode instead of a laser is used. By changing the path length of one of the interfering beams it is possible to select a region limited in depth where deformations are measured even if it is below the surface. Results on an artificial test object and on original terracotta fragments demonstrate the limits and the capabilities ofthe new method.
In this paper we present an optical derotator for scanning vibrometer measurements on rotating objects. The main part of an optical derotator is a rotating prism. Several concepts are known from literature. We have chosen a Dove prism because it can derotate the rotation of the specimen by simply watching through the prism, which rotates with half the speed. The design of our derotator is presented in this paper as well as a discussion of the system performance. In addition we show experimental measurement results on a fan rotating with 3000 rpm.
Die Notwendigkeit, flächenhaft strukturierte Oberflächen zu charakterisieren, führt vermehrt zum Einsatz optischer 3D-Mikroskopie in der Fertigungsmess- und Prüftechnik. Im Gegensatz zu den konventionell verwendeten taktilen Messsystemen, für die geeignete Normen und Prüfkörper zur Verfügung stehen, erweist sich die Rückführung mittels optischer 3D-Messtechnik gewonnener Daten als schwierig. Bedingt durch die Eigenheiten des jeweils verwendeten Systems kommt es zum Auftreten individueller Fehlertypen, die nur durch die Entwicklung und Kombination geeigneter Normale charakterisiert werden können.
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