... KG. Mangelernährung im Krankenhaus: Prävalenz, Ursachen und Konsequenzen. Alexander Koch 1 , ... more ... KG. Mangelernährung im Krankenhaus: Prävalenz, Ursachen und Konsequenzen. Alexander Koch 1 , Edouard Sanson 1 , Christian Trautwein 1 , Edmund Purucker 2. ... Crit Care Med 2004; 32: 350-357 6 Buzby GP, Williford WO, Peterson OL. et al. ...
Proceedings of Spie the International Society For Optical Engineering, Sep 6, 2010
Two-wavelength speckle interferometry (SI) is widely used for shape measurements of rough surface... more Two-wavelength speckle interferometry (SI) is widely used for shape measurements of rough surfaces. A surface under test arranged in an interferometer is illuminated with laser light having two different wavelengths. In the most simplified case the two interferograms are intensity-subtracted where the fringe distance in the detected pattern provides the information about the difference in height of the corresponding positions of the test surface. The distance between two fringes can be associated with the synthetic wavelength Λ, equivalent to the envelope of a beat frequency. In interferometry the use of the synthetic wavelength Λ is valid as long as the wavelengths of the two interfering waves are approximately equal. Since the height resolution is directly linked to the synthetic wavelength, a decrease of Λ will lead to an increased resolution of height. This statement, however, is only valid if the employed wavelengths are similar. We present how the choice of wavelengths of a Mach-Zehnder setup affects the resolution of the interferometer. On the one hand the term of synthetic wavelength is reviewed analytically concerning wavelengths with increasing Λλ. On the other hand we verified these results with a numeric simulation. In addition to the analytic model, the numeric simulation includes a more advanced surface model including roughness. As a result we provide a recommendation under what circumstances the decrease of Λ leads to an increased height resolution.
Electronic speckle pattern interferometry (ESPI) can provide accurate contour measurement in the ... more Electronic speckle pattern interferometry (ESPI) can provide accurate contour measurement in the micron range and short measurement times far below one second. An advantage of this method is that illumination axis and observation axis can be identical in contrast to e.g. triangulation. Therefore ESPI represents an interesting alternative to other optical measurement principles used for surface profiling. Typical surfaces in industrial applications often show discontinuities, like steps or holes. An unambiguous measurement of such surfaces is only possible if the synthetic wavelength is chosen larger than the largest surface step. Since the noise level introduced to the measurement increases proportional to the synthetic wavelength, unambiguous measurements suffer from a loss of accuracy. The solution for this problem is the combination of two or more synthetic wavelengths. In contrast to other publications (hierarchical, pixel-wise approach or temporal phase unwrapping) our novel area-based approach uses only two synthetic wavelengths minimizing measurement time and device complexity. The use of areas instead of pixels allows a lower signal to noise ratio and a smaller number of synthetic wavelengths (in our case only two) respectively, compared to the hierarchical pixel based approach. In this paper we present the steps required during pre-processing (laser tilt and wave front compensation) and the opportunities and drawbacks of different algorithms used for the fusion of the two images gained from different synthetic wavelengths.
Optical Measurement Systems for Industrial Inspection IV, 2005
Electronic speckle pattern interferometry (ESPI) can provide accurate contour measurement in the ... more Electronic speckle pattern interferometry (ESPI) can provide accurate contour measurement in the micron range and short measurement times far below one second. An advantage of this method is that illumination axis and observation axis can be identical in contrast to e.g. triangulation. Therefore ESPI represents an interesting alternative to other optical measurement principles used for surface profiling. Typical surfaces in industrial applications often show discontinuities, like steps or holes. An unambiguous measurement of such surfaces is only possible if the synthetic wavelength is chosen larger than the largest surface step. Since the noise level introduced to the measurement increases proportional to the synthetic wavelength, unambiguous measurements suffer from a loss of accuracy. The solution for this problem is the combination of two or more synthetic wavelengths. In contrast to other publications (hierarchical, pixel-wise approach or temporal phase unwrapping) our novel area-based approach uses only two synthetic wavelengths minimizing measurement time and device complexity. The use of areas instead of pixels allows a lower signal to noise ratio and a smaller number of synthetic wavelengths (in our case only two) respectively, compared to the hierarchical pixel based approach. In this paper we present the steps required during pre-processing (laser tilt and wave front compensation) and the opportunities and drawbacks of different algorithms used for the fusion of the two images gained from different synthetic wavelengths.
21st International Conference on Optical Fiber Sensors, 2011
Force-torque sensors are key elements in modern force feedback and robotic control applications. ... more Force-torque sensors are key elements in modern force feedback and robotic control applications. For special applications resistance against electromagnetic interference, high amount of load cycles or chemical resistance are important. For these applications, fiber-Bragg-grating based force torque sensors have been seen as possible solutions. Yet the implementation of a force-torque-sensor with six degrees of freedom and well conditioned sensitivities is still lacking demonstration. In this work, we demonstrate the design of a miniaturized fiber-Bragg-grating based force-torque sensor with six degrees of freedom using a numerical nonlinear programming technique. We implement the optimized structure and show its feasibility and sensitivity.
... KG. Mangelernährung im Krankenhaus: Prävalenz, Ursachen und Konsequenzen. Alexander Koch 1 , ... more ... KG. Mangelernährung im Krankenhaus: Prävalenz, Ursachen und Konsequenzen. Alexander Koch 1 , Edouard Sanson 1 , Christian Trautwein 1 , Edmund Purucker 2. ... Crit Care Med 2004; 32: 350-357 6 Buzby GP, Williford WO, Peterson OL. et al. ...
Proceedings of Spie the International Society For Optical Engineering, Sep 6, 2010
Two-wavelength speckle interferometry (SI) is widely used for shape measurements of rough surface... more Two-wavelength speckle interferometry (SI) is widely used for shape measurements of rough surfaces. A surface under test arranged in an interferometer is illuminated with laser light having two different wavelengths. In the most simplified case the two interferograms are intensity-subtracted where the fringe distance in the detected pattern provides the information about the difference in height of the corresponding positions of the test surface. The distance between two fringes can be associated with the synthetic wavelength Λ, equivalent to the envelope of a beat frequency. In interferometry the use of the synthetic wavelength Λ is valid as long as the wavelengths of the two interfering waves are approximately equal. Since the height resolution is directly linked to the synthetic wavelength, a decrease of Λ will lead to an increased resolution of height. This statement, however, is only valid if the employed wavelengths are similar. We present how the choice of wavelengths of a Mach-Zehnder setup affects the resolution of the interferometer. On the one hand the term of synthetic wavelength is reviewed analytically concerning wavelengths with increasing Λλ. On the other hand we verified these results with a numeric simulation. In addition to the analytic model, the numeric simulation includes a more advanced surface model including roughness. As a result we provide a recommendation under what circumstances the decrease of Λ leads to an increased height resolution.
Electronic speckle pattern interferometry (ESPI) can provide accurate contour measurement in the ... more Electronic speckle pattern interferometry (ESPI) can provide accurate contour measurement in the micron range and short measurement times far below one second. An advantage of this method is that illumination axis and observation axis can be identical in contrast to e.g. triangulation. Therefore ESPI represents an interesting alternative to other optical measurement principles used for surface profiling. Typical surfaces in industrial applications often show discontinuities, like steps or holes. An unambiguous measurement of such surfaces is only possible if the synthetic wavelength is chosen larger than the largest surface step. Since the noise level introduced to the measurement increases proportional to the synthetic wavelength, unambiguous measurements suffer from a loss of accuracy. The solution for this problem is the combination of two or more synthetic wavelengths. In contrast to other publications (hierarchical, pixel-wise approach or temporal phase unwrapping) our novel area-based approach uses only two synthetic wavelengths minimizing measurement time and device complexity. The use of areas instead of pixels allows a lower signal to noise ratio and a smaller number of synthetic wavelengths (in our case only two) respectively, compared to the hierarchical pixel based approach. In this paper we present the steps required during pre-processing (laser tilt and wave front compensation) and the opportunities and drawbacks of different algorithms used for the fusion of the two images gained from different synthetic wavelengths.
Optical Measurement Systems for Industrial Inspection IV, 2005
Electronic speckle pattern interferometry (ESPI) can provide accurate contour measurement in the ... more Electronic speckle pattern interferometry (ESPI) can provide accurate contour measurement in the micron range and short measurement times far below one second. An advantage of this method is that illumination axis and observation axis can be identical in contrast to e.g. triangulation. Therefore ESPI represents an interesting alternative to other optical measurement principles used for surface profiling. Typical surfaces in industrial applications often show discontinuities, like steps or holes. An unambiguous measurement of such surfaces is only possible if the synthetic wavelength is chosen larger than the largest surface step. Since the noise level introduced to the measurement increases proportional to the synthetic wavelength, unambiguous measurements suffer from a loss of accuracy. The solution for this problem is the combination of two or more synthetic wavelengths. In contrast to other publications (hierarchical, pixel-wise approach or temporal phase unwrapping) our novel area-based approach uses only two synthetic wavelengths minimizing measurement time and device complexity. The use of areas instead of pixels allows a lower signal to noise ratio and a smaller number of synthetic wavelengths (in our case only two) respectively, compared to the hierarchical pixel based approach. In this paper we present the steps required during pre-processing (laser tilt and wave front compensation) and the opportunities and drawbacks of different algorithms used for the fusion of the two images gained from different synthetic wavelengths.
21st International Conference on Optical Fiber Sensors, 2011
Force-torque sensors are key elements in modern force feedback and robotic control applications. ... more Force-torque sensors are key elements in modern force feedback and robotic control applications. For special applications resistance against electromagnetic interference, high amount of load cycles or chemical resistance are important. For these applications, fiber-Bragg-grating based force torque sensors have been seen as possible solutions. Yet the implementation of a force-torque-sensor with six degrees of freedom and well conditioned sensitivities is still lacking demonstration. In this work, we demonstrate the design of a miniaturized fiber-Bragg-grating based force-torque sensor with six degrees of freedom using a numerical nonlinear programming technique. We implement the optimized structure and show its feasibility and sensitivity.
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