检索结果-内蒙古大学图书馆

International Symposium on Optomechatronic Technologies, ISOT

作者： Florian Hirth Max Rossner Martin Jakobi Alexander W. Koch Institute of Measurement Systems and Sensor Technology Technische Universität München Munich Germany

Thin film reflectometry is a common way to monitor film thicknesses in numerous processes. Semiconductor and optics producing industries, e.g., require film thickness observation. Spectral reflectometry interrogation is one of several methods, which can be assessed by various algorithms depending on resolution and measuring range demands. Incident angle is a crucial parameter to these interrogation methods. Light, under different incident angles, produces different spectral reflectivity functions. These are integrated by a detector, in this case a spectrograph. Therefore, one needs to minimize the range of incident angles onto the measured object in order to increase the resolution of film thickness. Lateral resolution may also be a crucial parameter in some processes. Lateral resolution is a function of the range of incident angle, it increases with increasing angle range. These two crucial facts result in an estimate of measuring error introduced by the angle range under a given maximal lateral resolution. A measuring setup for a range of incident angle measurements is presented, as well as an example interrogation of a thin film under different incident angles.

关键词： Transistors Reflectometry Optical films Semiconductor thin films Semiconductor films Goniometers Monitoring Reflectivity Detectors Thickness measurement

来源：评论

学校读者我要写书评

暂无评论

Comparison of different peak detection algorithms with regards to spectrometic fiber Bragg grating interrogation systems

Comparison of different peak detection algorithms with regar...

引用

International Symposium on Optomechatronic Technologies, ISOT

作者： Thomas Bodendorfer Mathias S. Muller Florian Hirth Alexander W. Koch Institute of Measurement Systems and Sensor Technology Technische Universität München Munich Germany

The resolution of many optical measurement systems employing ID or 2D array sensors (e.g. CCD-cameras) is limited by the pixel-resolution of the detector. Subpixel algorithms allow to exceed this limit. This paper aims at fiber Bragg grating interrogators, which acquire the sensor signal spectrometrically. The accuracy of measurement of these systems is strongly depending on the used algorithms. Five different algorithms for peak detection are described and compared in theory and experiment. Most of these algorithms can be found both in literature and in different software-libraries (e.g. MATLAB, LabVIEW...) To compare the different algorithms, a single fiber Bragg grating sensor was used to acquire data with a spectrometric measurement system consisting of a lD-CCD-line-array, a superluminescent light source and a reflection grating. The same data was fed the five algorithms, such that the output signals are comparable. To characterize the peak-search algorithms the standard deviation of the output data has been computed for different frame rates and variable wide regions of interest around a FBG-peak. As a result we can provida a concise recommendation which of the analyzed algorithms is suitable for an application in spectrometric fiber Bragg grating interrogators.

关键词： Detection algorithms Spectroscopy sensor arrays Optical sensors Optical arrays sensor systems Fiber gratings Bragg gratings Signal resolution Detectors

来源：评论

学校读者我要写书评

暂无评论

An extrinsic Fabry-Perot interferometric optical fiber sensor system for hydrogen detection

An extrinsic Fabry-Perot interferometric optical fiber senso...

引用

20th International Conference on Optical Fibre sensors

作者： Yang, Zhen Zhang, Min Lei, Ming Yu, Xiujuan Liao, Yanbiao Lai, Shurong Tian, Qian Li, Qisheng Zhang, Yi Zhuang, Zhi State Key Laboratory of Precision Measurement Technology and Instruments Tsinghua University Beijing China Optical Fiber Sensor Lab Dept. of Electronic Engineering Tsinghua University Beijing China Institute of Systems Engineering CAEP Mianyang Sichuan China

ISBN: (纸本)9780819478146

An extrinsic Fabry-Perot interferometric (EFPI) optical fiber hydrogen sensor based on palladium silver (Pd-Ag) film is designed for hydrogen leakage detection. The sensing mechanism of such a sensor is based on the mechanical stress that is induced in the Pd-Ag film when it absorbs hydrogen. The sensor system which is portable and suitable for field detection is formed by a conventional coupler, a low-power LED operating at 850 nm, and a high resolution miniature spectrometer. To obtain the absolute length of the EFPI air gap, a cross-correlation signal processing method is *** sensor is suitable for monitoring concentrations of hydrogen below the lower explosive limit. © 2009 SPIE.

关键词： Binary alloys

来源：评论

学校读者我要写书评

暂无评论

A modified cross-correlation method for white-light optical fiber extrinsic Fabry-Perot interferometric hydrogen sensors

A modified cross-correlation method for white-light optical ...

引用

2009 International Conference on Optical Instruments and technology, OIT'09

作者： Yang, Zhen Zhang, Min Liao, Yanbiao Lai, Shurong Tian, Qian Li, Qisheng Zhang, Yi Zhuang, Zhi State Key Laboratory of Precision Measurement Technology and Instruments Tsinghua University Beijing China Optical Fiber Sensor Lab Dept. of Electronic Engineering Tsinghua University Beijing China Institute of Systems Engineering CAEP Mianyang Sichuan China

ISBN: (纸本)9780819478948

An extrinsic Fabry-Perot interferometric (EFPI) optical fiber hydrogen sensor based on palladium silver (Pd-Ag) film is designed for hydrogen leakage detection. A modified cross correlation signal processing method for an optical fiber EFPI hydrogen sensor is *** the applying of a special correlating factor which advises the effect on the fringe visibility of the gap length and wavelength, the cross correlation method has a high accuracy which is insensitive to light source power drift or changes in attenuation in the fiber, and the segment search method is employed to reduce computation and demodulating speed is fast. The Fabry-Perot gap length resolution of better than 0.2nm is achieved in a certain concentration of hydrogen. © 2009 SPIE.

关键词： Optical fibers

来源：评论

学校读者我要写书评

暂无评论

A basic study of ultrasonic shear wave elastography in tissue-mimicking phantoms

A basic study of ultrasonic shear wave elastography in tissu...

引用

IEEE International Workshop on Medical measurement and Applications (MEMEA)

作者： V. Rengaraju A.F.F. da Silva I. Sack Ch. Kargel Institute for Measurement and Automation Division of Sensor Technology and Measurement Systems Bundeswehr University of Munich Neubiberg Germany Department of Radiology Charité Universitatsmedizin Berlin Campus Mitte Berlin Germany

Since many diseases cause changes in the mechanical properties of soft tissues, it is of interest to image their elasticity. Detection of tumors in early stages is challenging but paramount for the proper treatment of patients and thus to reduce the mortality rate. Elasticity imaging (elastography) has great potential to improve tumor diagnosis and is being developed and tested by several research groups with ultrasound and magnetic resonance imaging (MRI). As opposed to MRI, medical ultrasound is widely available, much more cost-effective and most of all a real-time imaging modality. In this paper we evaluate ultrasonic shear wave elastography, a dynamic approach to determine soft tissue properties. Our feasibility study using tissue-mimicking phantoms demonstrates that low frequency shear wave oscillation amplitudes in the micrometer range can be measured using commercial ultrasound scanners in combination with a particular signal processing method. Stiff tissue regions (tumors) show smaller shear wave amplitudes than the surrounding normal tissue. Not only can the examination time be reduced from about 10-20 minutes (MRI) to a few seconds, it may also soon be possible to detect certain cardiovascular dysfunctions in real-time using ultrasonic shear wave elastography.

关键词： Imaging phantoms Magnetic resonance imaging Ultrasonic imaging Neoplasms Biological tissues Elasticity Diseases Mechanical factors Medical treatment Testing

来源：评论

学校读者我要写书评

暂无评论

FRICTION IDENTIFICATION AND COMPENSATION ON NANOMETER SCALE

引用

IFAC Proceedings Volumes 2008年第2期41卷 2014-2019页

作者： A. Amthor T. Hausotte Ch. Ament P. Li G. Jaeger Institute of Automation and Systems Engineering Technische Universität Ilmenau Germany Institute of Process Measurement and Sensor Technology Technische Universität Ilmenau Germany

This work concerns the modelling and experimental verification of the highly nonlinear friction behavior in positioning on the nanometer scale. The main goal of this work is to adjust and identify a simple dynamic friction model which allows a model-based estimation of the friction force in combination with the system inertia against displacement. Experiments in the pre-sliding and sliding friction regimes are conducted on an experimental setup. A hybrid two-stage parameter estimation algorithm is used to fit the model parameters based on the experimental data. Finally, the identified friction model is utilized as a model-based feedforward controller combined with a classical feedback controller to compensate the nonlinear friction force and reduce tracking errors.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Hysteresis modelling of NiZn-Ferrites

Hysteresis modelling of NiZn-Ferrites

引用

International Spring Seminar on Electronics technology

作者： Paul Fulmek Peter Haumer Gert Holler Department of Applied Electronic Materials Institute of Sensor and Actuator Systems University of Technology Vienna Vienna Austria Institute of Electrical Measurement and Measurement Signal Processing Graz University of Technology Austria

The energetic model of ferromagnetic hysteresis (EM) is applied to typical MnZn-ferrite-material. The EM simulates hysteresis loops from the demagnetised state up to saturation, including all sorts of major and minor loops and their dependence on the rate of change with time. Due to the high specific resistivity of ferrites the hysteresis losses dominate the losses of ferrite components, even at high frequencies. The EM is used to directly determine hysteresis losses for small excitations by a Rayleigh-law-approximation. The simulation results are compared to measurements on a typical commercial MnZn-ferrite-torus.

关键词： Magnetic hysteresis Magnetic materials Anisotropic magnetoresistance Toroidal magnetic fields Magnetic anisotropy Perpendicular magnetic anisotropy Biological system modeling Saturation magnetization Magnetostriction Equations

来源：评论

学校读者我要写书评

暂无评论

Applications of fibre optic temperature measurement

引用

Proceedings of the Estonian Academy of Sciences: Engineering 2007年第4期13卷 363-378页

作者： Hoffman, Lars Müller, Mathias S. Krämer, Sebastian Giebel, Matthias Schwotzer, Günther Wieduwilt, Torsten Measurement Systems and Sensor Technology Technical University of Munich Theresienstr. 90 80333 Munich Germany Distributed Measurement Systems Technical University of Munich Theresienstr. 90 80333 Munich Germany Institute of Photonic Technology Albert-Einstein-Strasse 9 07745 Jena Germany

Temperature measurement is crucial for many industrial processes and monitoring tasks. Most of these measurement tasks can be carried out using conventional electric temperature sensors, but with limitations. Particularly under harsh conditions, fibre optic temperature sensors show their advantages over conventional instrumentation. Three common principles of fibre optic temperature measurement are exemplarily examined: fibre Bragg gratings, Raman scattering and interferometric point sensors. Their working principles along with recent findings and applications of the sensing concepts are presented. So far their application is still limited to niche markets but with decreasing system prices fibre optic temperature sensing has great potential for further growth.

关键词： Fiber optic sensors

来源：评论

学校读者我要写书评

暂无评论

Fiber optic strain measurement for machine monitoring

Fiber optic strain measurement for machine monitoring

引用

Optical measurement systems for Industrial Inspection V

作者： Hoffmann, L. Mueller, M.S. Koch, A.W. Technische Universitaet Muenchen Institute for Measurement Systems and Sensor Technology Theresienstr. 90 80333 Munich Germany

ISBN: (纸本)0819467588

Monitoring machines during operation is an important issue in measurement engineering. The usual approach to monitoring specific machine components is using strain gauges. Strain gauges, however, may sometimes not be used if conditions are harsh or installation space is limited. Fiber optic sensors seem to be an alternative here, but dynamic health monitoring has been difficult so far. The focus of this field study is to measure vibration characteristics of machine parts during operation using fiber optic sensors with the objective of early damage detection. If that was possible, downtime and maintenance costs could be minimized. Therefore a field test for dynamic fiber optic strain measurement on a roller bearing was carried out. The test setup consisted of the bearing built into a gear test stand and equipped with an array of fiber Bragg grating sensors. Fifteen fiber sensors were interrogated with a sample rate of 1 kHz and the vibration pattern was extracted. The radial load distribution was measured with high spatial resolution and a high degree of compliance with simulation data was found. The findings suggest that fiber optic health monitoring for machine components is feasible and reasonable. Especially with the help of distributed sensing on various components extensive health monitoring on complex technical systems is possible.

关键词： Optical fibers

来源：评论

学校读者我要写书评

暂无评论

Stress effect on optical nonlinear waveguide sensor

Stress effect on optical nonlinear waveguide sensor

引用

作者： El-Khozondar, H.J. El-Khozondar, R.J. Shabat, M.M. Koch, A.W. Islamic University Department of Electrical and Electronics Engineering Palestinian Authority P.O.Box 108 Gaza Strip Al-Aqsa University Physics Department Palestinian Authority Gaza Gaza Strip Islamic University Physics Department Palestinian Authority P.O.Box 108 Gaza Strip Technische Universität München Institute for Measurement Systems and Sensor Technology D-80290 München Germany Max Planck Institute for the Physics of Complex Systems Nöthnitzer Straße 38 01187 Dresden Germany

It has been observed in photoelectric devices that stresses and strains can cause inhomogeneous distribution of the refractive index which affects their performance. The purpose of this paper is to study the stress effect on the behavior of optical waveguide sensor containing a dielectric film sandwiched between a linear substrate and a nonlinear cladding. The cladding refractive index profile is assumed to have Kerr like intensity dependence. The effective refractive indices and mode shapes of the optical waveguide sensor subject to different stress states are calculated analytically. The effect of such variation on the light intensity and implications on the sensor sensitivity are investigated. It is found that stress can affect the optical sensitivity performance.

关键词： Optical sensors

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：