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Bodendorfer T.,Institute for Measurement Systems and Sensor Technology | Hesske A.,Institute for Measurement Systems and Sensor Technology | Sax C.,Institute for Measurement Systems and Sensor Technology | Koch A.W.,Institute for Measurement Systems and Sensor Technology
Optoelectronics and Advanced Materials, Rapid Communications | Year: 2012

Speckle-Interferometry (SI) is a powerful tool for fast, robust and non-contact measurements of displacement, vibration, roughness or shape. One of the key components in SI is the light source. Typical light sources are gas lasers, which meet all requirements like high intensity, homogeneous beam profile, and high degree of coherence. Due to large size, temperature control and high costs these types of laser can often not be used as an illumination source in SI-systems. Next to standard edge-emitting diode lasers, vertical cavity surface emitting lasers (VCSEL) are a promising alternative light source in SI. In this work, standard edge-emitting lasers are compared to VCSELs regarding the applicability in interferometric applications. Source


Wiesent B.R.,Institute for Measurement Systems and Sensor Technology | Dorigo D.G.,Institute for Measurement Systems and Sensor Technology | Julich F.,Institute for Measurement Systems and Sensor Technology | Simsek O.,Institute for Measurement Systems and Sensor Technology | Koch A.W.,Institute for Measurement Systems and Sensor Technology
Optoelectronics and Advanced Materials, Rapid Communications | Year: 2011

The viscosity is one of the most important properties of lubricants. This parameter has to be adopted to the specific operation conditions where the lubricant is used. We used laser induced fluorescence (LIF) with deep UV excitation at 248 nm and a fibre optic probe to measure viscosity levels of fresh synthetic oil samples. Three types of synthetic oils each with seven different viscosity levels in the range of 32 to 320 mm2/s were measured. A small low cost fibre coupled grating spectrometer was used as interrogator. The different viscosities can be distinguished by their fluorescence intensity distribution in the spectral range 320 to 550 nm. The measured fluorescence spectra of all three oils show characteristic features which allow a clear classification of the fresh oil viscosity levels. To predict fresh oil viscosity levels in a linear model, a partial least squares regression (PLS1) was applied to the gained spectral data set. We reached a good model quality of viscosity levels of all three types of fresh oil. The used setup can also be constructed in a robust and very cost effective manner using a deep UV 250 nm LED and a low resolution VIS grating spectrometer. In-situ measurement of oil viscosity in production processes is possible as well. Source

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