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Innovative Metrology 2017

Rückblick: Innovation Messtechnik 2015

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A fourier-optical method to evaluate the diameter of spherical phase objects for the contactless measurement of transient pressure sequences in liquids

Ergebnisse aus der Diplomarbeit wurden in der Publikation "Pattern Centroid Estimation as Basis for Accurate Optical Pressure Measurement", auf der IASTED Conference 2006, Visualization, Imaging and Image Processing, 28-30 August 2006, in Palma de Mallorca, von Herrn Niedermayer präsentiert.

Alexander Niedermayer

Alexander Niedermayer

The localised measurement of highly transient pressure sequences at hardly accessible regions within hydraulic systems is a profund measurement problem. This diploma-thesis researches the idea of injecting a small gas-bubble at the point of interest within the liquid and evaluate its pressure dependent diameter optically. Therefore different ways of injecting bubbles are investigated and a thermodynamic model of the bubble is developed to identify influence of disturbance variables such as surface tension. For evaluating the diameter of the bubble fourier-optics is particularly suitable. The research of the influence of a spherical phase object to coherent light is the basis for the construction of the optical configuration and image processing algorithms. A measurment configuration is being created for gauging bubbles of different diameter under various pressure. Selected measurement results are presented to demonstrate the realizability of the presented approach.

Figure 1: Optical setup for acquiring spatial spectra

Figure 1: Optical setup for acquiring spatial spectra

Figure 2: Spatial spectrum of an diffracting object of approximately 230 micrometer diameter. The low frequency components in the center are masked out by a Fourier-filter

Figure 2: Spatial spectrum of an diffracting object of approximately 230 micrometer diameter. The low frequency components in the center are masked out by a Fourier-filter

January 2007