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International Conference on Indoor Positioning and Indoor Navigation (IPIN)

作者： Jörg Blankenbach Abdelmoumen Norrdine Geodetic Institute Department of Geodetic Measurement Systems and Sensor Technology Technische Universität Darmstadt Darmstadt Germany

A positioning system is introduced which overcomes the limitations of existing indoor positioning systems by the use of artificial quasi static magnetic fields. The proposed DC magnetic signals show no special multipath effects and have excellent characteristics for penetrating various obstacles. In this contribution the theory of coil-based magnetic fields as well as the basic function principle of the positioning system are described. Furthermore, a prototype that is currently under development is presented.

关键词： Magnetic fields Coils Magnetic field measurement Mathematical model Accuracy Equations Magnetic sensors

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Modelling the capacitive coupling of sensors applied to the contactless inspection of planar electronics

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Procedia Engineering 2010年 5卷 400-403页

作者： M. Koerdel F. Alatas A. Schick S.J. Rupitsch R. Lerch Corporate Technology CT T DE HW2 Siemens AG Munich Germany Department of of Sensor Technology Friedrich-Alexander-University Erlangen-Nuremberg Germany Institute of Measurement Systems and Sensor Technology Technische Universität München Germany

A model aimed to describe the capacitance between probe electrodes and the conductive parts of planar electronic devices is presented. The probe electrodes are the constitutive part of a sensor chip used in an inspection system which is exclusively based on capacitive coupling and employed for the inspection of devices such as flat panel displays and printed electronic circuits. Finite element (FE) simulations of the sensor signal are used to determine the model parameters and to verify the obtained results. The capacitive coupling for arbitrary configurations of parallel arranged conductor tracks and various distances between the tracks and the sensor chip is reproduced by the model. Absolute values of the capacitance with deviations below 5% can be obtained.

关键词： Flat panel display (FPD) Planar electronic device Contactless inspection system Capacitive coupling Finite element (FE) simulation Nonmatching grids

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Configuration of a sparse network of LIDAR sensors to identify security-relevant behavior of people

Configuration of a sparse network of LIDAR sensors to identi...

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Unmanned/Unattended sensors and sensor Networks VI Conference

作者： Wenzl, Konrad Ruser, Heinrich Kargel, Christian Bundeswehr University Munich Institute for Measurement and Automation Division of Sensor Technology and Measurement Systems 85577 Neubiberg/Munich Germany

ISBN: (纸本)9780819477866

Surveillance is an important application of sensor networks. In this paper it is demonstrated how a sparse network of stationary infrared (IR) sensors with highly directional, stationary beam patterns based on the LIDAR principle can be used to reliably track persons. Due to the small number of sensors and their narrow beam patterns a significant portion of the area to be surveilled is not directly assessed by the sensors. To nonetheless achieve reliable tracking of moving targets in the entire area to be monitored, we employ the most appropriate sensor network configuration and propose a probabilistic tracking approach. The behavior of a person moving through the area of observation is classified as "normal" or "abnormal" depending upon the trajectory and motion dynamics. The classification is based on a linear Kalman prediction. © 2009 Copyright SPIE - The International Society for Optical Engineering.

关键词： Optical radar

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Detection and tracking of humans with a sparse network of LIDAR sensors

Detection and tracking of humans with a sparse network of LI...

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Intelligent Sensing, Situation Management, Impact Assessment, and Cyber-Sensing

作者： Ruser, Heinrich Wenzl, Konrad Kargel, Christian Bundeswehr University Munich Institute for Measurement and Automation Division of Sensor Technology and Measurement Systems 85577 Neubiberg/Munich Germany

ISBN: (纸本)9780819476180

The applicability of a sparse sensor network with only two sensor nodes and a small number of directional LIDAR sensors to detect and track humans in an area of surveillance is investigated. The detection and tracking performances are evaluated for various positions of the two nodes as a function of the number of sensors per node and the sensor beamwidths. A quality factor incorporating the area coverage ratio and the position error is introduced to find the best network configuration with a minimal number of sensors yielding a position accuracy sufficient for the task at hand. Extensive simulations and measurements with two laserscanners to emulate the LIDAR sensors were carried out for straight trajectories uniformly distributed over the area of surveillance. In order to improve the tracking performance, we used a Kalman filter based approach. As in our application a spatial mean RMS position error of approx. 0.6 m is sufficient, each of the two sensor nodes must be equipped with 4 LIDAR sensors with a -3dB-beamwidth of 12. ©2009 SPIE.

关键词： Optical radar

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Performance analysis of interrogators for Fiber Bragg Grating sensors based on arrayed waveguide gratings

Performance analysis of interrogators for Fiber Bragg Gratin...

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Optical measurement systems for Industrial Inspection VI

作者： Buck, Thorbjorn C. Muller, Mathias S. Plattner, Markus Koch, Alexander W. Technische Universitaet Muenchen Institute for Measurement Systems and Sensor Technology Theresienstr. 90 80333 Munich Germany

ISBN: (纸本)9780819476722

Fiber Bragg grating (FBG) sensors have proven to be adaptable for monitoring various physical quantitites like temperature, strain, or even vibrations and acoustic noise. Several interrogation methods, like spectroscopic evaluation, interferometric interrogation, active scanning or active filtering systems or passive filtering systems are capable of monitoring the wavelengths of the FBG sensors. Among the passive filtering systems, interrogators based on arrayed waveguide gratings (AWG) have shown to be promising candidates for sensing with FBGs, especially for high-frequency measurement tasks. Whereas the resolution- and the accuracy-dependency on light intensity of direct wavelength determining systems like spectrometers or scanning filter systems can be minimized by data processing algorithms, the performance of passive filtering based interrogators is more sensitive regarding uncertainties induced by electrical amplifier noise, FBG peak shape, light source intensity, etc.. The influence of different sources of uncertainties for AWGbased interrogators on the accuracy of the wavelength determination are investigated by an analytical model. The model is evaluated by a numerical simulation. It is shown how strongly the accuracy and the resolution of such an interrogator depend on the mentioned sources of uncertainties. Considering the obtained results, one can say that FBG interrogators based on arrayed waveguide gratings have, including the shown restrictions, the potential for rugged, compact and cost effective high accuracy wavelength interrogators. © 2009 SPIE.

关键词： Fiber Bragg gratings

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Infrared imaging to quantify the effects of nicotine-induced vasoconstriction in humans

Infrared imaging to quantify the effects of nicotine-induced...

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Thermosense XXXI

作者： Brunner, Siegfried Kargel, Christian Institute for Measurement and Automation Division of Sensor Technology and Measurement Systems Bundeswehr University Munich Werner-Heisenberg-Weg 39 85579 Neubiberg/Munich Germany

ISBN: (纸本)9780819475657

Smoking is the most significant source of preventable morbidity and premature mortality worldwide (WHO-2008). One of the many effects of nicotine is vasoconstriction which is triggered by the autonomic nervous system. The constriction of blood vessels e.g. of the skin's vascular bed is responsible for a decrease of the supply with oxygen and nutrients and a lowering of the skin temperature. We used infrared imaging to quantify temperature decreases caused by cigarette smoking in the extremities of smokers and also monitored heart rate as well as blood pressure. The results - including thermograms showing "temporary amputations" of the fingertips due to a significant temperature drop - can help increase the awareness of the dangers of smoking and the success of withdrawal programs. Surprisingly, in our control persons (3 brave non-smoking volunteers who smoked a cigarette) we also found temperature increases suggesting that vasodilation (widening of blood vessels) was provoked by cigarettes. To verify this unexpected finding and eliminate effects from the 4000 chemical compounds in the smoke, we repeated the experiment following a stringent protocol ruling out physiological and psychological influences with 9 habitual smokers and 17 nonsmokers who all chew gums with 2 mg of nicotine. Task-optimized digital image processing techniques (target detection, image-registration and -segmentation) were applied to the acquired infrared image sequences to automatically yield temperature plots of the fingers and palm. In this paper we present the results of our study in detail and show that smokers and non-smokers respond differently to the administration of nicotine. © 2009 SPIE.

关键词： Image segmentation

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Spectral peak tracking for enhanced fiber optic sensing

Spectral peak tracking for enhanced fiber optic sensing

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Optical measurement systems for Industrial Inspection VI

作者： Plattner, Markus P. Brand, C.N. Mair, T. Schupfer, S. Buck, T.C. Koch, A.W. Technische Universität München Institute for Measurement Systems and Sensor Technology Theresienstr. 90 80333 Munich Germany

ISBN: (纸本)9780819476722

Within this work, we describe our newly developed interrogation scheme for fiber optic sensing applications. This measurement system will be utilized in Ariane launchers for monitoring temperature and mechanical stress distribution during flight. The acquired sensing data can be used to control propulsion unit an thrusters and thereby adapt the flight path in a way that damage on the launcher is prevented. In order to detect the peak wavelength of e.g. fiber Bragg grating (FBG) sensors, a tunable laser source based on a modulated-grating laser diode is able to scan through a more than 40nm wide spectrum in the infrared region. Several sensors with different spectral answers can be placed inside one sensor fiber and then interrogated sequentially. The magnitudes of the reflected intensities depend on the actual sensor position that is determined by the measurand (e.g. temperature). One single sensor is scanned by a variable number of spectral sampling points and the spectral answer of the sensor is then calculated by centroid algorithms. Depending an the spectral width of one sensor, the number of sensors that shall be interrogated and the required sampling points per sensor, a maximum sampling frequency of 240kHz is achievable with our hardware. Contrary to comparable systems, our interrogator is capable of switching to any available wavelength of its spectrum within a couple of nanoseconds. Therefore standard continuous sweeping through the entire spectrum is not necessary. This results in a new measurement scheme, wherein spectral gaps between consecutive sensors do not need to be scanned and can be skipped. Since most of the spectrum consists of the gaps between the sensors, overall measurement time is thereby reduced significantly. One problem arises from this measurement scheme: Due to the fact that the sensor's spectral answers vary in time, a special algorithm for tracking the spectral movement has to be implemented. The scope of this work is the description,

关键词： Fiber Bragg gratings

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Thin film interferometer using a light source with spectrally non-equidistantly distributed sampling points

Thin film interferometer using a light source with spectrall...

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Optical measurement systems for Industrial Inspection VI

作者： Hirth, Florian Dudeck, Sven Jakobi, Martin Gerhard, Detlef Koch, Alexander W. Technische Universitaet Muenchen Institute for Measurement Systems and Sensor Technology Theresienstrasse 90 80333 Munich Germany Siemens AG CT PP 4 Germany

ISBN: (纸本)9780819476722

Numerous processes, e.g. in semiconductor and optics producing industries require film thickness observation. These measuring systems depend on different working principles, e.g. spectral reflectometry or ellipsometry. The spectral reflectometry interrogation method can be evaluated by various algorithms depending on resolution and measuring range demanded. All methods require a broad spectral distribution of the light source in order to sample the signal sufficiently for parameter extraction. Spectral sampling is often realized using a spectroscope, which produces equidistant sampling points in frequency space. In contrast to conventional spectrally broad light sources, the one employed here emits several spectral lines, which are non-equidistantly distributed. It also introduces problems like variations of intensity in the output spectrum and narrow wavelength bands, in which the reflected spectrum can be investigated. Non-equidistant sampling points additionally imply problems in conventional analysis algorithms, e.g. a FFT anticipates equidistant sampling points. Narrow wavelength bands imply little information to interrogate at the same spectral resolution of the interrogator. Strong variations of intensity lead to high noise levels at wavelengths with low intensities. Therewith, accuracy, resolution and measuring range are limited. An interrogator based on a Hg-Ar light source, a fiber coupler and a commercial spectroscope is described in this work. Both, accuracy and measuring range, are investigated by simulation and are experimentally proven on a glass on silicon demonstrator. Introducing an advanced algorithm, uncertainties invoked by the source's spectral and intensity distribution are minimized and resolution as well as measuring range are increased. © 2009 SPIE.

关键词： Thin films

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Experimental investigation of polarization rotation in twisted optical fibers

Experimental investigation of polarization rotation in twist...

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International Symposium on Optomechatronic Technologies, ISOT

作者： Hala J. El-Khozondar Mathias S. Muller Thorbjorn C. Buck Rifa J. El-Khozondar Alexander W. Koch Institute for Measurement Systems and Sensor Technology Technische Universitä t München Munich Germany Institute for Measurement Systems and Sensor Technology Technische Universitä t München Munich Munich Germany

The twist induced polarization rotation in birefringent optical fibers is well understood and has been treated in the late seventies. We recently derived a formulation of the polarization rotation in twisted optical fibers using a tensorial coupled mode approach, that, other than existing theories, employs a fixed reference frame. This is interesting for fiber sensing applications, where the perturbing effects onto the fiber, such as strains induced by embedding the fiber into a host material, are conventionally given in a fixed laboratory reference frame. Hence, the derived theory can easily be integrated into existing formulations in the laboratory reference frame. In this work we demonstrate the experimental verification of the derived *** mechanically twist an optical fiber using an automated test stand and recording the change in polarization. The results are in close agreement with the theory.

关键词： Optical fiber polarization Optical fibers Optical fiber theory Optical fiber testing Laboratories Birefringence Optical coupling Capacitive sensors Optical materials Automatic testing

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Fiber Bragg grating-based acceleration sensor

Fiber Bragg grating-based acceleration sensor

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International Symposium on Optomechatronic Technologies, ISOT

作者： Mathias S. Muller Thorbjorn C. Buck Alexander W. Koch Institute of Measurement Systems and Sensor Technology Technische Universität München Munich Germany

We present the design process of a fiber Bragg grating based fiber-optic single-axis acceleration sensor with minimized crosstalk. Crosscoupling of non-directional accelerations is minimized by introducing a unique double-membrane fixture of the sensor's mass of inertia leading to an almost diagonal form of the sensors stiffness-matrix. The sensor's resonance frequency, the sensor's sensitivity towards the stiffness of the spring-mass system and the mass of inertia are calculated from an analytical model and are verified by FEM simulation of the sensor. A singleaxis sensor design yielding a resonance frequency of 6.0 kHz with a sensitivity of Deltalambda = 1 pm/g at a non resonant acceleration is proposed.

关键词： Acceleration Fiber gratings Bragg gratings sensor systems Resonance Accelerometers Optical fiber polarization Optical fiber sensors Resonant frequency Optical fibers

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