Proceedings Volume 7133

Fifth International Symposium on Instrumentation Science and Technology

Jiubin Tan, Xianfang Wen
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Proceedings Volume 7133

Fifth International Symposium on Instrumentation Science and Technology

Jiubin Tan, Xianfang Wen
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Volume Details

Date Published: 12 January 2009
Contents: 11 Sessions, 167 Papers, 0 Presentations
Conference: International Symposium on Instrumentation Science and Technology 2008
Volume Number: 7133

Table of Contents

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Table of Contents

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  • Front Matter: Volume 7133
  • Instrument Science: Fundamental Theory and Methodology
  • Instruments and Systems
  • Sensors and Converters
  • Signal and Image Processing
  • Electromagnetic Measurement and Automated Testing
  • Laser Measurement Techniques and Instruments
  • Holography and Diffraction Optics and Instruments
  • Advanced Optics Measurement Techniques
  • Optoelectronics System Design and Optoelectronic Instruments
  • Nanotechnology and MEMS
Front Matter: Volume 7133
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Front Matter: Volume 7133
This PDF file contains the front matter associated with SPIE Proceedings Volume 7133, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.
Instrument Science: Fundamental Theory and Methodology
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Advanced research on nonlinearity in heterodyne interferometer
Wenmei Hou, Wenbo Cui
Recent development of research on the nonlinearity of the heterodyne interferometers provides an approach to eliminate the nonlinearity of heterodyne interferometer using a simple phase compensation system by rotating a polarizer which is set up before the detector in the interferometer.[17] This paper shows the experiment results which proved its general validity for elimination of the nonlinearity errors whether it is a first-order or a higher-order error. It explains which accuracy can be expected and provides the application opportunities based on theoretical analyses and experiment results.
Functions and three dimensional parameters of surface texture
Qunfen Qi, Xiaojun Liu, Xiangqian Jiang
This paper presents the relationship between the functions and five types of three dimensional parameters: height, spatial, functions and related, miscellaneous and hybrid parameters of surface texture carried out by ISO TC 213. A novel calculation method of 'zero wear' volume is proposed according to the value change of the function volume parameters of Vvv, Vvc and Vmp before and after abrasion. In order to check the difference of three dimensional parameters in engineering surface texture measurement, a surface texture measurement of silicon wafer before and after polish was carried out.
Test procedures and artefacts for optical coordinate metrology
Ulrich Neuschaefer-Rube, Wiebke Ehrig, Michael Neugebauer, et al.
Optical measurements are performed in coordinate metrology in a wide range of applications, ranging from large-scale workpieces with dimensions of several meters down to microstructures with &mgr;m-dimensions, using a large number of different measurement devices and sensors. These different devices and sensors must be tested to check their compliance with the specifications, to trace back the measurement results and to compare different devices. Thus, appropriate procedures and measurement standards (artefacts) are necessary. We present test procedures and artefacts for optical measurement systems similar to the well-known test procedures for classical tactile coordinate measuring machines (CMMs) according to the international standard ISO 10360. It is important that the surface characteristic of the artefacts is cooperative to the sensor. Appropriate artefacts were realized and tested. The main focus of this paper is on micro-artefacts. Furthermore, task-related standards to trace back specific measurement tasks were developed. By means of micro-contour artefacts, the measurement characteristics on critical geometries can be evaluated and compared. By means of a micro-gear standard, the measurement uncertainty on micro-planetary gear can be evaluated. The measurement deviations of measurement systems in the automotive industry can be determined with the special artefacts to test sensors for inline measurements.
Symmetrically associated combination method for accuracy verification of Coordinate Measuring Machines
Hongtao Wang, Xiaohuai Chen, Yetai Fei
The paper is enlightened by the traditional combination verification method, provides a new detection way to CMM which is the combination of space one-dimension balls combination. It uses one-dimension balls instead of the standard ruler of the tradition combination verification method, adopts special researched detection equipment to CMM making one-dimension balls to three-dimension. The CMM processes the space random line with symmetry associating and comparing measurement method, and then uses the least-squares method to the measured data to obtain the measurement error of the space line, consequently realizes the measurement accuracy detection of the CMM.
Test method based on neural network for crosstalk faults in digital circuits
Zhongliang Pan, Ling Cheng, Guangzhao Zhang
The increase in signal switching speed and density of digital circuits leads to the crosstalk faults of interconnection lines, which may cause undesirable effects and even logic errors in the circuit. A new test method based on the neural network models of digital circuits is proposed in this paper for the crosstalk faults in digital circuits. The neural network corresponding to digital circuit is built, and the test vectors of the crosstalk faults are generated by computing the minimum energy states of neural network. A chaotic evolutionary strategies algorithm is designed to compute the minimum energy states. The algorithm combines the features of chaotic systems and evolutionary strategies, and takes full advantages of the stochastic properties and global search ability of the two techniques. Experimental results on a lot of benchmark circuits show that the approach proposed in this paper can be used to get the test vectors of the crosstalk faults if the crosstalk faults are testable.e
Generation of test patterns for defect and noise in VLSI circuits using binary decision diagrams
Binary decision diagram can be used to give canonical representation to logic functions and manipulate functions by simple and efficient graph algorithms. In this paper, the generation of test pattern based on binary decision diagrams is studied for stuck-at faults and crosstalk faults in digital circuits. The binary decision diagrams corresponding to the normal circuit and faulty circuit are built, respectively. A binary decision diagram is built by the XOR operation of the two binary decision diagrams, each input assignment that leads to the leaf node labeled 1 is a test vector of the faults. Besides, the binary decision diagram is very sensitive to the variable ordering, the variable ordering used can have a significant impact on the number of nodes. A chaotic genetic algorithms is presented in this paper, which is used to find a variable ordering that minimizes the size of a binary decision diagram to get the test vectors of the faults in digital circuits in the shortest possible test time. Experimental results obtained with a lot of digital circuits show that all the test vectors of a fault can be obtained using the method presented in this paper.
Analysis of mechanical dynamometer based on bifurcation theory
Yi-hui Cui, Zhi-an Yang, Chao Yun, et al.
In order to study the nonlinear characteristics of a mechanical dynamometer, a mathematic model is established using the Lagrangian method. The adequate and essential conditions for homoclinic orbit and periodical orbit of the system are discussed using the model. A bifurcation diagram of the external excitation is obtained through simulation. Simulation results clearly show the transformation from periodic motion to chaotic motion. The system can enter the chaotic motion through the quasi-periodic route; Poincare sections and phase portraits validate the doubling bifurcation motion of the system. Therefore, typical nonlinear vibration can be found in this system, especially when the excitation frequency is changing between its lower and higher values. For the purpose of improving the measuring accuracy, the parameters of the mechanical dynamometer should be designed to keep the system in periodic and quasi-periodic motions..
Approach method based on brightness temperature for multi-spectral thermometer
Guibin Yuan, Zhigang Fan, Xiaogang Sun, et al.
It is known from relationship between brightness temperature and true temperature of a multi-spectral thermometer that brightness temperature is equal to true temperature if the wavelength approaches to zero. Thus true temperature can be acquired by fitting brightness temperatures and corresponding wavelengths using non-linear least squares method. This method was named AMBT (approach method based on brightness temperature). The emissivities of metals and nonmetals were used to simulate AMBT at a temperature from 160K to 3000K. The effective wavelengths chosen are 3.00, 3.25, 3.50, 3.75, 4.00, 4.25, 4.50 and 4.75 micron in the atmospheric window of 3-5 micron. While in another atmospheric window of 8-12 micron, the effective wavelengths are 8.00, 8.50, 9.00, 9.50, 10.00, 10.50, 11.00 and 11.50 micron. Actual measurements were used to verify the effectiveness of AMBT. Results show that the errors are always smaller at a lower temperature and increase with the increase in temperature. The errors of 3-5 micron are lower than those of 8-12 micron. At same temperature, the errors of metals are lower than those of non-metals. AMBT is more accurate to be used at a low temperature than be used at a high temperature. AMBT can be used to identify materials in common use, offering a new method to get true temperature of low temperature objects.ï
Mathematical model of strip specimens for application of pulse-heating technique
Peng Xiao, Qingwei Wang, Jingmin Dai
The dynamic measurement of selected thermophysical properties of electrically conducting solids in the temperature range of 1100 K to the melting point was conducted using strip specimens, for simultaneous measurement of the normal spectral emissivity by using integrating sphere reflectometry. The method is based on rapid resistive self-heating of the specimen from room temperature to any desired high temperature in less than several seconds by the passage of an electical current pulse through it to measure the pertinent quantities, as current, voltage, and randiance temperature, with sub-millisecond resolution. The estimation of heat capacity and hemispherical total emissivity is based on various computational methods derived by assuming that the temperature was uniform in the central part of the specimen. The validity of this approach was verified when specimens with large cross sections and when the temperature on the specimen surface was measured. A numerical model was established with the temperature variations across the specimen was taken into consideration. The mathematical model established can be used in the simulation experiments to access the magnitude of specific phenomena due to the temperature gradient inside the specimen, in relation to the specimen geometry and to the specific thermophysical properties of different materials.
Research of zero crossing point real-time detecting of quasi-sinusoidal signal
Yanjun Dong, Xiaobin Zhang
Based on the analysis of sine or quasi-sine period signal zero crossing point detecting of computer-based detecting and control system, Fourier transform is employed to get input signal's key spectrum to build waveform characteristic dictionary, and the signal's differentia can supply more information of input signal's zero crossing point. Methods are proposed referring to circumstances, and results of simulation prove efficiency.
Variable sampling plan for reliability of irreparability system in exponential process
Jiqing Shi, Shuning Wang
A variable sampling plan is proposed for the reliability of an irreparable system, which can be expressed as average reliable working time (ARWT). ARWT is a variable described by an exponential distribution. According to the requirements of producer and customer for sampling inspection, the plans of producer and customer and a general plan are given separately. The paper suggests taking the limit acceptable average reliable working time as the acceptance standard. The plan of producer is designed by taking into consideration both the design index of average reliable time and the risk of producer. The plan of customer takes into consideration both the refusing standard of reliable working time and the risk of customer for designing. The general plan considers all risks of both producer and customer. There is a great difference between plans in sampling numbers and protecting emphases.
Statistical characters of antenna rod slant errors
Li-xin Jin, Lian-Jun Wang, Song-lin Yang
It is obvious that antenna rod slant errors affect the plane position of survey points when Stetting-out centerline by GPS RTK technique. This paper put forward that antenna rod slant errors is abide hypotheses of uniform distribution, then deduce a procedure for its mathematical expectation and variance formula .and makes thorough analyses the effects of the random errors and achieves useful conclusions. So that it could be the academic foundation for the GPS RTK survey technique.e
Speed ratio control for cars equipped with metal v-belt continuously variable transmission
Meilan Zhou, Bin Zhang, Jiabin Wen
In order to study the control effect of speed ratio change on fuel economy performance of vehicles under complex working conditions, a mixed fuzzy-PI control strategy is proposed, and a dynamic simulation model is established for the best fuel economy. Simulation and analysis are conducted using the model under different typical operating conditions. Simulation results show that the speed ratio mixed fuzzy-PI controller has a better following characteristics and higher accuracy compared to a conventional fuzzy controller. Even in the case of external disturbance, the target engine speed can still be maintained at the most economic working point. According to the proposed control strategy, road test has been done under various running situations with DEAWOOD MatizII passenger car used as an experimental sample car. The test results verify further that the model established is correct and the control strategy proposed for the speed ratio is valid, and the reasonable match between engine and continuously variable transmission (CVT) is achievable.
Simulation of air gap vibration on aerostatic bearing under flow/structure coupled conditions
Qian Wang, Jianjin Wu, Dongsheng Li
The vibration of aerostatic bearing air gap is one of the main factors, which restricts the precision of nano-processing and nano-measurement. Finite volume method was employed to obtain the air gap steady flow of different air gap thicknesses for the demonstration of vibrations under flow/structure coupled conditions. The unsteady flow of air gap was analyzed numerically by using the air gap flow & boundary movement control equations to get the pressure distribution on the slide surface and the amplitude of air gap for further study on the self-excited vibration of aerostatic bearings. Numerical analyses show that the highest aerostatic bearing amplitude is relative to the difference between load capacity and gravity at the initial moment as air gap rises, and the final air gap thickness has nothing to do with the initial air gap thickness. The results presented a new analytic demonstration for the research on the reduction of aerostatic bearing vibration.
Effect of probe offset on ultra-precision measurement of circular profile
Jingzhi Huang, Jiubin Tan
In order to further improve the ultra-precision measuring accuracy of circular profile, the sources of probe offset error was analyzed and one-parameter measurement model was established that with probe offset parameter only, and it was concluded that probe offset has a significant effect on the measurement of an object with a small size or large profile deviation; the two-parameter measurement model that with probe offset error d and eccentricity error (e, &agr;) was simultaneously analyzed, and the accurate interaction relationship between d and e is obtained. Simulation results show that probe offset error has a significant amplifying action to eccentricity error, and the measurement error increases as probe offset error increase. This paper provides the basis for further improvement of ultra-precision measuring accuracy of circular profile.
Damping vibration studies of scanning near-field optical microscope
Terry Yuan-Fang Chen, Haw-Long Lee
Scanning near-field optical microscopy (SNOM) is one of the major proximal probe technologies for obtaining high-resolution images beyond the diffraction limit of light and to fabricate nanometer-scale structures. The effect of interactive damping on the flexural vibration frequency for the scanning near-field optical microscope (SNOM) fiber probe based on the Timoshenko beam (including the effects of shear deformation and rotary inertia) theory, has been analyzed. The effects of the transverse contact stiffness, damping factor and the ratio of different probe dimensions on the damping vibration frequency were studied. The results show that increasing the ratio of probe length to radius increases the damping vibration frequency of mode 1. The damping vibration frequencies, based on the Bernoulli-Euler beam theory and the Timoshenko beam theory, are compared. When the contact stiffness is very large for the higher modes, the effects of shear deformation and rotary inertia on the frequency becomes significant. Furthermore, increasing the damping factor increases the vibration frequency, especially for dimensionless damping factor &egr;f >0.4
The study and realization of standard dynamic signals of dynamic characteristic calibration for high precision displacement sensor
Xue Zi, Ye Shu Liang, Ye Xiao You
Sine signals and ellipse signals with frequencies (1-100) Hz are selected to calibrate the steady-state response characteristic of the displacement sensors, and impulse signals are selected to calibrate the transient-state response characteristic of the displacement sensors under the condition of non-periodic signal, after analyzing the working states and the frequency response range of the high precision displacement sensors during the actual measurement. These standard dynamic signals can be realized and traced to the length standard by a dynamic characteristic calibration and traceability device for the high precision displacement sensor that developed by NIM. And the dynamic characteristics of the inductance and capacitance sensors are calibrated by using this calibration and traceability device. It can be shown that the amplitude and phase deviations become bigger when the frequency is increased. The sensor accuracy used in the dynamic condition is reduced.
Instruments and Systems
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Analysis of optical theodolite dynamic accuracy evaluation method
Xie Yun
Optical theodolite dynamic accuracy evaluation has long been a difficulty in measurement system. In classical method, it is based on positioning technology to calculate the angles. But this can't meet the accuracy requirement of evaluation needs. In this paper, we introduced regress-to-center correction theory from classical geodetic measurement. Based on this, we use high accurate angle-measure equipment to collect data, use eccentric angle, and eccentricity to process azimuth and elevation which collected by optical theodolite, and this helped to avoid the affection caused by position error to angle accuracy. This can help to increase the angle accuracy of acceptance info-source to ten more times. It is of great value in optical theodolite dynamic accuracy evaluation application.
Precision measurement of scroll profiles
Y. Arai, A. Inada, W. Gao
Scroll compressors are widely used in air conditioner compressor, vacuum pump and so on. Profile measurement of a scroll compressor is important for improving compression efficiency. This paper describes the involute profile measurement of a scroll compressor by using r-&Tgr; measurement system for the manufacturing line. Involute profile measurement system consists of X-Z-&Tgr; stage and contact type scanning probe. Scanning probe draws Archimedean spiral locus by X-&Tgr; stage. Output of scanning probe includes profile error and difference of Archimedean spiral and involute. To confirm that influence of coordinate system error, simulation was carried out. It was confirmed that profile measurement error was a one tenth or less compared with the rotation setting error of work piece. From the simulation result of Y-directional offset between rotation center of &Tgr; stage and center of probe sphere, to achieve the required accuracy of profile measurement, it is necessary to reduce or measure the probe alignment error to under the required accuracy order. Fixed scroll outside-involute profile error is measured by developed measurement system. The difference from CMM result is seen in the center part. It is caused by residual Y directional alignment error of scanning probe. Excluding the center part, measurement result is corresponding to CMM result.
Impact response evaluation of force transducer for use in falling weight deflectometer system
Yusaku Fujii, Takahiro Fujyu, Haruki Okano
The impact response of a force transducer in a falling weight deflectometer system is evaluated by an optical method. In the method, a mass is made to collide with a force transducer and the impact force is measured highly accurately as the inertial force acting on the mass. A pneumatic linear bearing is used to realize linear motion with a sufficiently small friction acting on the mass, i.e., the moving part of the bearing. The method is an improved variation of the Levitation Mass Method, which has been proposed and developed by the first author. The impact force, which has a maximum value of approximately 1.66 kN and a full width at half maximum of approximately 5.0 ms, has been applied and measured using the Levitation Mass Method with the standard uncertainty of approximately 3.3x10 N. This corresponds to 2x10-2 (2%) of the maximum applied force in the experiments. The present status of the method and the points to be considered for the future improvements are discussed.
Design of rehabilitation robot hand for fingers CPM training
Hongfu Zhou, T. W. Chan, K. Y. Tong, et al.
This paper presents a low-cost prototype for rehabilitation robot aide patient do hands CPM (continuous passive motion) training. The design of the prototype is based on the principle of Rutgers Master II glove, but it is better in performance for more improvement made. In the design, it uses linear motors to replace pneumatic actuators to make the product more portable and mobile. It increases finger training range to 180 degree for the full range training of hand finger holding and extension. Also the prototype can not only be wearing on palm and fore arm do training for face to face with finger move together, but also be put in the opposite hand glove wear direction for hand rehabilitation training. During the research, Solidworks is used as the tool for mechanical design and movement simulation. It proved through experiment that the prototype made in the research is appropriate for hand do CPM training.
Theoretic research on effective viewing field of spin vision measurement system
Shuhua Yan, Shaowei Shen, Chunlei Zhou, et al.
The spin vision measurement system based on a two-CCD vision sensor is widely used in the wind tunnel experiments. The math-model of vision measurement system is established, and the computing formula for the size of the effective viewing field is derived by using the geometric imaging theory. The effective viewing field is studied in detail, which considers the size of airplane model and the measuring accuracy of attitude parameters. And the relationships among structural parameters of this system and parameters of CCD itself are analyzed. Finally, using the self-programming emulating package, the simulation results are obtained, which have an important meaning on structure design of the spin vision measurement system.
The valuation of uncertainty on cylinder shell resonating density meter
X. W. Sui, Y. Li, G. X. Zhang, et al.
In order to improve the measurement accuracy of cylinder shell resonating density meter, the paper presents many means of methods to lower the measurement error from the liquid temperature, pressure, viscidity and gas bubble in the liquid, and designs a novel cylinder shell resonating density meter. Taking typical calibration experiments as example, the paper gives the detailed steps of calculating uncertainty component of the cylinder shell resonating density meter, and values the combined uncertainty. The experiments and analysis show the combined uncertainty is 0.96kg/m3 when the measurement result is 785.16 kg/m3, and the relative uncertainty is 0.12%.
Identification of inner parameters in laser radar measuring system through system error analysis
Zhengchun Du, Shujie Zhang, Yongfei Wei, et al.
This paper concerns the study of error modeling and inner parameter identification of 3D laser radar measuring system (LRMS) equipped with 2D laser sensor and electric servo motor, for the potential application of on-site measurement of the heavy forging object with temperature as high as 1000°C Firstly the physical and geometric model of 3D laser radar measuring system is presented. Detail discussion about the deterministic error and random error of the measuring system is conducted. Consequently the discipline of the deterministic error and the variation laws of random errors are achieved by the nonlinear equations set through the coordinate transformation. Finally based on the above discuss the identification method of inner geometrical parameter of the measuring system is presented by using the local linearization for nonlinear equations with Tailor Series Expansion Formula and the Least Square Algorithm. Therefore its measuring accuracy has been improved significantly. The results show this calibration method is helpful to the similar application of other measuring systems.
Modification and prototype test of staple gun
Kuang-Yih Tsue, Gwo-Jen Wu
This paper presents how to design a staple gun and verify its data through simulation. The staple gun was estimated and analyzed using 'ANSYS' software and the results were compared with those obtained through experiments. In this research, a supporting position for the spring inside the staple gun was damaged after hundreds of loads, and there was no data about the impact force when staples were shot into the targets. Therefore, a prototype test system is developed to validate the data through simulation. In this case, the results are quite close to each other before they can be used to help the manufacturer to improve its structure. This prototype test system is completed through PC-based automation software. The simulation model was modified to develop the next new products for saving costs and time. Because the impact force, coming out from the staple gun is pretty large, it should be restricted within a certain limit to keep the user safe.
FPGA-based distortion correction for laser spot inspection system
Zhaoxia Zhang, Yang Han, Xiaodong Chen, et al.
This paper focuses on the correction of radial distortion in the laser spot vision inspection system, which is the main cause for the inaccuracy of measurement results. An efficient circuit architecture using a low cost FPGA (field programmable gate array) and a hardware look-up table for distortion correction is presented. The polynomial fitting formula between the pixels in the distorted image and those in the corrected one will be calculated under software circumstance, then converted into the addresses of FLASH memory as a look-up table. By access to FLASH memory instead of complex arithmetic, FPGA can obtain the spatial correction data, according to which the gray scale can be gained and corrected with a nearest-neighbor principle. Experiment results illuminate the relative distortion declines from 23.88% to approximately 1%, and the average error of the spot center is within 1mm. The reduction of distortion error facilitates the application of the short-focus and wide-angle lenses, and therefore promotes the development of portable and miniaturized instruments.
Loop-by-loop modeling of whole-closed-loop 2D high-precision motion platform
Shu-liang Ye, Dong-sheng Li, Tian-tai Guo, et al.
A 2D high-precision motion unit plays an important role in an automatic optical inspection (AOI) system, and its positioning accuracy and speed have an decisive effect on the inspection accuracy, efficiency and stability of the AOI system, but the present AOI systems cannot ensure the high speed and high-precision at the same time. To solve this problem, an automatic optical platform is developed, using the whole-closed-loop, fast, high-precision positioning technology to construct the mathematical models of its motion control unit, including models of current loop, velocity loop and position loop from inside to outside. Experiments were made on the motion platform using a laser interferometer. Experimental results show that the 2D motion platform can be used to reach a scanning speed of 20m/s and a positioning accuracy of 9ìm in a work area of 300mm * 3000mm with a load of 5kg.
Measuring and balancing dynamic unbalance of precision centrifuge
Yafei Yang, Xin Huo
A precision centrifuge is used to test and calibrate accelerometer model parameters. Its dynamic unbalance may cause the perturbation of the centrifuge to deteriorate the test and calibration accuracy of an accelerometer. By analyzing the causes of dynamic unbalance, the influences on precision centrifuge from static unbalance and couple unbalance are developed. It is considered measuring and balancing of static unbalance is a key to resolving a dynamic unbalance problem of precision centrifuge with a disk in structure. Measuring means and calculating formulas of static unbalance amount are given, and balancing principle and method are provided. The correctness and effectiveness of this method are confirmed by experiments on a device under tuning, thereby the accurate and high-effective measuring and balancing method of dynamic unbalance of this precision centrifuge was provided.
Application of master-slave multi-communication system in pilotless airborne mapping equipment
Ying Zhang, Junjiang Chen, Wensheng Wang
This paper presents a master-slave multi-communication system designed with several micro-controllers used as master and slave controllers to set signal the lamp to realize point-to-point communication through the RS422 interface. By describing a typical example of this system and the blue print of hardware and the flowchart of software, the reliable work of the system has been proved. The circuits of system are very simple and practical, and they can be used to realize all the functions of a pilotless airborne mapping equipment. It also has a strong anti-jamming capability due to its balanced transfer scheme with single transmitter and multiple receivers. It is very efficient in protecting the integrity and correctness of transmitted and received signals, avoiding the collision of signals through the bus, satisfying the communication among several micro-controllers in a single system and forming a special communication network.
Determination of optimal observable subspace for strapdown inertial navigation systems through observability analysis
Yafei Yang, Xin Huo
The determination of unobservable states is important in consideration of system performance during initial alignment. The aim of observability analysis is concluded as follows: 1) finding the observable states or linear combinations of these states; 2) finding those states whose measurements turn the system into a completely observable; 3) separating the system into observable and unobservable subsystems. In this paper, the system equation and measurement equation of SINS for Kalman filtering are given. The Observability of initial alignment process of SINS is analyzed by means of singular value decomposition method. Degree of observability for every state can be computed by preceding method, the three unobservable states of INS are obtained; therefore optimal observable subspace is determined by structure decomposition method. For proving the correctness and effectiveness of this proposed method, a Kalman filter is designed. The Kalman filtering results are obtained. By comparing these results with results of observability analysis, the uniform conclusion is obtained. Before designing a Kalman filter, the observability of every systematic state can be known by use of the singular value decomposition method of the observable matrix, i.e. degree of observability for every state can be computed. Therefore observable vector and optimal observable subspace may be determined. The correctness and effectiveness of this proposed method was proven by analyzing results of Kalman filtering. This method can be used for direct design of a Kalman filter.
High-speed random equivalent sampling system for time-domain reflectometry
Jian-hui Song, Feng Yuan, Zhen-liang Ding
Time domain reflectometry (TDR) has been commonly used for testing cable for years. The waveform attenuation and distortion of TDR pulse is an inherent problem for the correct definition of arrival time and propagation velocity of traveling wave. For the purpose of obtaining the required information of incident and reflected pulse waveform, a highspeed random equivalent sampling (RES) system with 65ps sampling resolution is proposed for a high-resolution TDR. The problem of data storage and communication caused by high sampling rate is solved by using both digital signal processors (DSP) and field programmable gate arrays (FPGA). The detail architecture of the implemented circuit and software is described, including the control logic and data processing algorithm. The real-time sampling rate of the system is up to 125MHz, with 15.4GHz equivalent sampling bandwidth. The test results show that the proposed system can be used as a high-speed data acquisition and processing unit.
Error measuring system of rotary Inductosyn
Chengjun Liu, Jibin Zou, Xinghe Fu
The inductosyn is a kind of high-precision angle-position sensor. It has important applications in servo table, precision machine tool and other products. The precision of inductosyn is calibrated by its error. It's an important problem about the error measurement in the process of production and application of the inductosyn. At present, it mainly depends on the method of artificial measurement to obtain the error of inductosyn. Therefore, the disadvantages can't be ignored such as the high labour intensity of the operator, the occurrent error which is easy occurred and the poor repeatability, and so on. In order to solve these problems, a new automatic measurement method is put forward in this paper which based on a high precision optical dividing head. Error signal can be obtained by processing the output signal of inductosyn and optical dividing head precisely. When inductosyn rotating continuously, its zero position error can be measured dynamically, and zero error curves can be output automatically. The measuring and calculating errors caused by man-made factor can be overcome by this method, and it makes measuring process more quickly, exactly and reliably. Experiment proves that the accuracy of error measuring system is 1.1 arc-second (peak - peak value).
Design of integrated and networked multidimensional grating digital readout
Li Chang, Hui Xu, Guoyi Xiu
The grating digital readout is the key measurement feedback device of the numerical control system and base of the equipment manufacturing industry. With the development of the complex machining, the multi-axis linkage is a new direction of the numerical control system, which needs the multidimensional measurement. Based on all digital grating moiré fringe subdivision theory, the paper introduces the design of integrated and networked multidimensional grating digital readout with an embedded system-on-chip ZA7V that is a complete field configurable system-on-chip with a 32- bit ARM7TDMI processor core, a programmable logic matrix, a robust memory subsystem and a high-performance dedicated internal bus. Networked functions include Ethernet interface, CAN bus interface, USB bus interface and GPRS interface so that the grating digital readout can access the device network, workshop network, intranet network and Internet. The simulation results and experimental data prove that the realization of the integrated and networked multidimensional grating digital readout. It will be widely used in the numerical control system and machining center.
Architectural design of flue gas continuous emission monitoring system
Hongfu Zhou, Liangzhong Jiang, Yong Tang, et al.
The paper presents the architectural design of flue gas continuous emission monitoring system, which uses computer, acquisition card and serial port communication card as hardware in the flue gas continuous emission monitoring system. In the CEMS, continuous emission monitoring system, it monitors dust in the flue gas, SO2, NOX, and some parameter on the flue gas emission, which includes mass flow, pressure, and temperature. For the software in the monitoring system, the research designs monitoring program in VC++, and realizes flue gas monitor with the architecture.
Dynamic modeling and analysis of large-scale antenna structure
Long Shen, Zhenbang Gong, Liang Liu, et al.
In order to do the systematical dynamic modeling and analysis of the Ku-band 16meter antenna satellite ground station used a satellite telecommunication, We calculated the eigenvalues of the the Ku-band 16meter antenna structure, and used the SAP5, a large structure analysis software, to do the finite element calculation and analysis. The first ten band eigenvalues of the antenna structure were calculated; And the results showed that the minimum natural frequency was 2.075 Hz. Furthermore, based on National Military Standard, we measured the system frequency of the Ku-band 16meter antenna satellite ground station and got the minimum natural frequency of 2.249Hz. So there is quite good agreement between the theoretical minimum natural frequency (2.075 Hz) and the measuring minimum natural frequency (2.249Hz). This shows that dynamic modeling and analysis of a large-scale antenna structure system is effective.
A 3D error measurement system for CNC machining tools
Wenyuh Jywe, Y. R. Jeng, Yitsung Li, et al.
A new system for measuring the errors of three-axis machines is presented in this paper. It is composed of a planar encoder system and a magnetic telescoping ball bar. The individual signals of three-axis displacement can be simultaneous obtained. The errors of the three-axis machines, geometric error, kinematic error, wobble error and volumetric error, can be effectively measured. The system is characterized by short set up time, low capital requirement, high measuring speed and high accuracy.
Neural networks based in process tool wear prediction system in milling wood operations
Krzysztof Szwajka, Joanna Zielinska-Szwajka, Jaroslaw Gorski
Neural networks in process tool wear prediction system has been proposed and evaluated in this study. A total of 100 experimental data have been received for training through a back-propagation neural networks model. The input variables for the proposed neural networks system were feed rate, cutting speed from the cutting parameters, and the force in the x,y-direction collected online using a dynamometer. After the proposed neural networks system had been established, two experimental testing cuts were conducted to evaluate the performance of the system. From the test results, it was evident that the system could predict the tool wear online with an average error of ±0.037 mm.
Microfabricated scanning near-field probe for sub-terahertz spectroscopy
This paper reports design, fabrication and evaluation of a novel scanning near-field probe for terahertz (THz) local time domain spectroscopy (THz-TDS). A microfabricated scanning near-field optical microscopy (SNOM) probe was assembled with a low-temperature-grown gallium arsenide (LT-GaAs) photoconductive antenna. The probe structure was evaluated and determined by a finite-difference time-domain (FDTD) numerical simulation. The assembly was used as the THz emitter and local THz source. Another LT-GaAs antenna situated at the opposite side was used as the detector. A THz-TDS measurement using the microfabricated SNOM probe and photoconductive antenna was performed.
Nanometric edge profile measurement of cutting tools on a diamond turning machine
Takemi Asai, Yoshikazu Arai, Yuguo Cui, et al.
Single crystal diamond tools are used for fabrication of precision parts [1-5]. Although there are many types of tools that are supplied, the tools with round nose are popular for machining very smooth surfaces. Tools with small nose radii, small wedge angles and included angles are also being utilized for fabrication of micro structured surfaces such as microlens arrays [6], diffractive optical elements and so on. In ultra precision machining, tools are very important as a part of the machining equipment. The roughness or profile of machined surface may become out of desired tolerance. It is thus necessary to know the state of the tool edge accurately. To meet these requirements, an atomic force microscope (AFM) for measuring the 3D edge profiles of tools having nanometer-scale cutting edge radii with high resolution has been developed [7-8]. Although the AFM probe unit is combined with an optical sensor for aligning the measurement probe with the tools edge top to be measured in short time in this system, this time only the AFM probe unit was used. During the measurement time, that was attached onto the ultra precision turning machine to confirm the possibility of profile measurement system.
Sputter deposited zinc oxide photoconductive antenna for terahertz time-domain spectroscopy
In this paper, we report on the design and fabrication of zinc oxide (ZnO) photoconductive antenna for a terahertz (THz) pulse emitter and detector, and its integration with scanning near-field optical microscopy probe. The fabricated ZnO photoconductive antennas are evaluated in a THz time-domain spectroscopy measurement system. The resistivity of ZnO deposited by rf sputter at the room temperature was 9.6..104 ·cm. The bandwidth of ZnO photoconductive antenna was up to 1 THz.c
Mass image data storage system for high resolution aerial photographic survey
Luan Zen, Jiubin Tan, Zhongwen Zhao
In order to make it possible for an image data acquisition and storage system used for aerial photographic survey to have a continuous storage speed of 144 MB/s and data storage capacity of 260GB, three main problems have been solved in this paper. First, with multi-channel synchronous DMA transfer, parallel data storage of four SCSI hard disks is realized. It solved the problem of the data transfer rate too high for direct storage. Then, to increase the data transfer rate, a high speed BUS based on LVDS and a SCSI control circuit based on FAS368M were designed. It solved the problem of PCI BUS limiting the storage speed. Finally, the problem of the SCSI hard disk continuous storage speed declining led by much time interval between two DMA transfers is solved by optimizing DMA channel. The practical system test shows that the acquisition and storage system has a continuous storage speed of 150 MB/s and a data storage capacity of 280GB. Therefore, it is a new storage method for high speed and mass image data.
Automatic calibration of dial gauges based on computer vision
Jun Zhao, Haiping Feng, Ming Kong
Against the image characteristics of dial gauges, an automatic detection system of dial gauges is designed and implemented by using the technology of computer vision technology and digital image processing methods. Improved image subtraction method and adaptive threshold segmentation method is used for previous processing; a new method named as region-segmentation is proposed to partition the dial image, only the useful blocks of the dial image is processed no the other area, this method reduces the computation amount greatly, and improves the processing speed effectively. This method has been applied in the automatic detection system of dial gauges, which makes it possible for the detection of dial gauges to be finished intelligent, automatically and rapidly.
Metabolic measurements in cell culture and tissue constructs
This paper concerns the study and use of biological cells in which there is a need for sensors and assemblies for the measurement of a diverse range of physical and chemical variables. In this field cell culture is used for basic research and for applications such as protein and drug synthesis, and in cell, tissue and organ engineering. Metabolic processes are fundamental to cell behaviour and must therefore be monitored reliably. Basic metabolic studies measure the transport of oxygen, glucose, carbon dioxide, lactic acid to, from, or within cells, whilst more advanced research requires examination of energy storage and utilisation. Assemblies are designed to incorporate bioreactor functions for cell culture together with appropriate sensing devices. Oxygen consumption by populations of cells is achieved in a flowthrough assembly that incorporates O2 micro-sensors based on either amperometry or fluorescence. Measurements in single cell are possible with intra-cellular fluorophores acting as biosensors together with optical stimulation and detection. Near infra-red spectroscopy (NIRS) is used for analysis within culture fluid, for example for estimation of glucose levels, as well as within cell populations, for example to study the respiratory enzymes.£
Monitoring of electric-cardio signals based on DSP
Yi-xin Yan, Hui-nan Sun, Shuang Lv
Monitoring of electric-cardio signals is the most direct method of discovering heart diseases. This article presents an electric-cardio signal acquisition and processing system based on DSP. According to the features of electric-cardio signals, the proposed system uses the AgCl electrode as electric-cardio signals sensor, and acquires analog signals with AD620 as the prepositional amplifier, and the digital system equipped is with TMS320LF2407A DSP. The design of digital filter and the analysis of heart rate variation are realized by programming in the DSP. Finally the ECG is obtained with P and T waves along with obvious QRS multi-wave characteristics. The system has low power dissipation, low cost and high precision, which meets the requirements for medical instruments.
Sensors and Converters
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Optical fiber gas sensing system based on FBG filtering
An optical fiber gas sensing system based on the law of Beer-Lambert is designed to determine the concentration of gas. This technique relies on the fact that the target gas has a unique, well-defined absorption characteristic within the infrared region of electromagnetic spectrum. The narrow-band filtering characteristic of optical fiber Bragg grating is used to produce the narrow spectrum light signal. An aspheric objective optical fiber collimator is used in the system as an optical fiber gas sensing detector to improve the sensitivity and stability. Experimental results show there is a high measuring sensitivity at 0.01%, and the measuring range goes beyond 5%.
Inductosyn angle measuring system error based on AD2S80 resolver-to-digital converter
Zhenhuan Wang, Xijun Chen, Ren Li
This paper presents an inductosyn angle measurement system based on AD2S80 resolver-to-digital converter. The reason why the reference signal is not orthogonal with the excitation signal is analyzed, and a mathematical model is established for the error. The correctness of the error model is proved by measuring data. The error that the reference signal not be orthogonal with the stimulating magnetism signal causes the quadratic sine harmonic error which has a significant effect on the precision of the angle measurement system.
Real-time indoor monitoring system based on wireless sensor networks
Zhengzhong Wu, Zilin Liu, Xiaowei Huang, et al.
Wireless sensor networks (WSN) greatly extend our ability to monitor and control the physical world. It can collaborate and aggregate a huge amount of sensed data to provide continuous and spatially dense observation of environment. The control and monitoring of indoor atmosphere conditions represents an important task with the aim of ensuring suitable working and living spaces to people. However, the comprehensive air quality, which includes monitoring of humidity, temperature, gas concentrations, etc., is not so easy to be monitored and controlled. In this paper an indoor WSN monitoring system was developed. In the system several sensors such as temperature sensor, humidity sensor, gases sensor, were built in a RF transceiver board for monitoring indoor environment conditions. The indoor environmental monitoring parameters can be transmitted by wireless to database server and then viewed throw PC or PDA accessed to the local area networks by administrators. The system, which was also field-tested and showed a reliable and robust characteristic, is significant and valuable to people.
Analysis of the optimal package diameter of FBG pressure sensor
Lihui Liu, Yongtai He, Fang Li, et al.
In this paper, a theoretical analysis of the optimal package diameter of fiber Bragg grating (FBG) pressure sensors is presented. We use the theory of elastic to analyze the relation between the pressure sensitivity and the package diameter of FBG with d ifferent materials, structures. Then we can get the optimal package diameter of FBG pressure sensor for a certain package structure and material. Through the following experiments, it can be proved that the theoretical analysis is correct. This analysis could not only significantly enhance the pressure sensitivity, but also provide the optimal package diameter of FBG for the practical applications.
Design of nodes for embedded and ultra low-power wireless sensor networks
Jun Xu, Bo You, Juan Cui, et al.
Sensor network integrates sensor technology, MEMS (Micro-Electro-Mechanical system) technology, embedded computing, wireless communication technology and distributed information management technology. It is of great value to use it where human is quite difficult to reach. Power consumption and size are the most important consideration when nodes are designed for distributed WSN (wireless sensor networks). Consequently, it is of great importance to decrease the size of a node, reduce its power consumption and extend its life in network. WSN nodes have been designed using JN5121-Z01-M01 module produced by jennic company and IEEE 802.15.4/ZigBee technology. Its new features include support for CPU sleep modes and a long-term ultra low power sleep mode for the entire node. In low power configuration the node resembles existing small low power nodes. An embedded temperature sensor node has been developed to verify and explore our architecture. The experiment results indicate that the WSN has the characteristic of high reliability, good stability and ultra low power consumption.
Quartz tuning fork temperature sensor testing system based on programmable chip
Jun Xu, Bo You, Lihua Hu, et al.
A digital temperature testing system has been developed using a programmable chip for a ZY cutting-type quartz tuning fork temperature sensor. The system consists of hardware and software functionalities and it is implemented on an Altera Cyclone II EP2C35 Field Programmable Gate Array including a NIOS core processor. To satisfy the real time processing constraints on the one hand, and parameterization on the other hand, part of the algorithm are implemented in hardware and others are implemented in software. Experimental results indicate that the testing system can be used to measure the temperature with an accuracy of 0.01 degree C, and the effective resolution is better than 0.003 degree C in the range of - 20 degree C to 140 degree C.
Characteristic analysis of contactless transformer
Chengjun Liu, Jibin Zou, Xinghe Fu
The mathematical model of reflected reactance supplied by voltage source is established to deeply analyze the coupling characteristic and power transfer characteristic of a contactless transformer used in angle sensor. Firstly, the molding method is studied based on the structure feature of contactless transformers with pot core. Then, the primary and secondary equivalent circuits of a transformer supplied by voltage source are obtained by using the mutual inductance model with contactless electromagnetic coupling structure. On the basis of which, the mathematical model of reflected reactance is derived, and the expressions of some characteristics parameters, such as voltage gain and output power, are obtained. Finally, the prototype of a contactless transformer is made according to the design parameters calculated by means of the finite element model. The experiment shows that the mathematical model can be used to accurately analyze the coupling characteristics and power transfer characteristics of contactless transformers.
Research on the permanent magnet synchronous motor control system based on additional and sensing windings
Hong-xing Wu, Bao-quan Kou, Li-yi Li
The rotor position of permanent magnet synchronous motor is mostly detected by mechanical encoders, which increase the complexity and cost but reduce the reliability of the control system, moreover limit the applications of permanent magnet synchronous motor in certain special situations. In this paper, one method that can detects the rotor position, winding temperature and the rotor flux meanwhile through additional windings instead of changing motor structure is proposed. An additional winding is connected in the orientation opposite to that of the stator winding, and then a high-frequency current is injected into the winding to calculate the rotor position, sense the main motor winding temperature and the rotor flux by detecting the variations of the additional winding resistance and back electromagnetic force (EMF). Experimental results validate that the method is effective and feasible.
The study of an electromechanical actuator with a resolver as the position sensor
Hong-xing Wu, Bao-quan Kou, Li-yi Li
Space electromechanical actuator uses a permanent magnet synchronous motor as the servo component, which features in small dimension, high accuracy and reliability. At the same time the position signal of the electromechanical actuator is significant for the system performance. Resolver is widely used due to its high temperature tolerance, humidity resistance, impact resistance, anti-jamming and other advantages. In this paper, the position sensor of the electromechanical actuator servo system uses a resolver as the rotor position sensor, designes the resolver signal processing circuit that can get absolute position signal directly, and translate it into digital corresponding quantity. Decoder chip and controller chip can be linked through the data bus, I/O port and SPI port in order to interface with the digital signal processor (TMS32F2808) chip which can receive and process the signals of the rotor position. With the space vector control strategies of Permanent magnet synchronous motor, better performance has been achieved. Experiments show that the design is compact, high reliability, high precision and has achieved satisfactory results.
Structure design and experimental research on the electric-pneumatic transfer device with piezoelectric actuator
Dong-Ming Li, Bao-yuan Sun, Wei Wang, et al.
Electric-pneumatic transducer and electric-pneumatic positional valve has advantages of fire protection, explosion protection and lifetime dilatation etc, and are widely used in industrial automatic production. In this paper, two new electric-pneumatic transfer device with piezoelectric actuator whose structure and operating principle are proposed. One is based on the principle of nozzle-flapper, the other is based on opening-closing. Experiment research was carried on and the results show that the new transfer devices can meet requirement of air pressure output between 0.02MPa and 0.1MPa in industrial field with low voltage, which provides good basis of development of electric-pneumatic transducer valve with new piezoelectric structure.
Design of GMI micro-magnetic sensor based on Co-based amorphous alloys for space applications
Yanwei Jiang, Jiancheng Fang, Peipei Han, et al.
Giant magneto-impedance (GMI) magnetic sensors have great potential to be next generation of magnetic sensors for space applications. This article concerns the design of a GMI micro-magnetic sensor based on amorphous alloys using the theory of GMI effect, which covers sensing materials, construction of sensor, working principle and signal detection method. Co-based amorphous ribbons are selected as the preferred sensing elements since they have good soft magnetic properties, such as high saturated magnetization, low coercivity, high magnetic permeability and excellent mechanical properties. Co-based amorphous ribbons of 20 ~ 60 m thick and 1 ~ 3mm wide are fabricated and their magnetic properties, mechanical properties and GMI effects are studied for their applications as GMI sensing elements. Sensor output can be acquired by utilizing phase-sensitive detection method with higher noise suppression. This work provides a preliminary investigation into the high performance of a micro-magnetic sensor for space applications.
WSN multilateral localization algorithm based on Tikhonov regularization method
Lei Wang, Hong-ming Li, Xiao-tong Du
In wireless sensor network (WSN) applications, node localization for complex system monitoring is a key problem to be resolved. A new localization algorithm Based on Tikhonov regularization method is proposed for the ill-posed multilateral localization problem, which includes building location model, selecting regularization parameter and optimizing reference node number. In this algorithm, through converting ill-posed multilateral localization problem into norm minimization problem, a feasible regularization matrix can be constructed and regularization parameter for different situations can be determined using Morozov discrepancy criterion. The validity of the newly proposed method is verified through experiments. Test results show that the location precision of the proposed algorithm is better than that of the Maximum Likelihood Estimation (MLE) method, and the measurement error is about 1 meter while regularization parameter &agr; is about 600 and the reference node number is 5.
Wet gas measure by tapered tube variable area ring orifice
Guomin Xue, Yi Shen
Great difficulties exist in wet gas flow measuring by means of standard orifice plate since the rangeability can only reach 3:1, with serious pressure loss plus liquid aggregation near the upstream orifice plate. Therefore, it is necessary to improve the structure of the standard orifice plate. This paper presents a sort of tapered tube variable area ring orifice device for wet gas measure, which is designed structurally by combination of a tapered tube, an inner circle-shaped movable baffle, a precision spring and a displacement sensor. Accordingly, a wet gas flow equation is shown that features the substitution of displacement for pressure difference. The rangeability can be as large as 15:1 in the case that the area ratio of the variable flow path is designed to be 5:1. The hydromechanical numerical simulation results indicate that both rate field and pressure field inside the device are stable and the pressure loss is one-third of the standard orifice plate. Further, the problems of liquid aggregation and pressure ducts block are avoided.H
Research for the bearing grinding temperature on-line monitoring system based on the infrared technology
Zongxiang Huang
On-line monitoring to temperature of grinding arc is an important link absolutely necessarily in bearing grinding automation. This paper introduced a new method, which is to monitor grinding temperature via infrared ray, designed the engineering model of grinding arc temperature on-line monitoring system, and presented with components of grinding temperature automatic detection system and made analysis to workflow of the system. It brought forward the thought to establish factory grinder and central monitoring room to constitute Local Area Network so as that the central monitoring room could transfer information as grinding dosage and finishing of grinding wheel to operators of each grinder. Through analysis to influential factors of measurement results of that system, the paper provides with solutions. Technical tests validate that relative measurement error of that system is less than 0..5°C, which could better achieve on-line monitoring and alarm of grinding temperature and promote surface quality and productivity of grinding parts significantly.
Achievement of digital control technology on high-power silicon controlled rectifier
Yinhan Gao, Qiang Sun, Changying Liu
To fulfill the need of experimental DC supply of subway inverter, this paper designs and develops a set of rectifier system of 160kW, output voltage can be adjusted from 500V to 900V. This article uses SCR as main switches, the trigger circuit adopts digital trigger circuit, the control of whole system is achieved by DSP. The main control method is digital PI, which used to control the output DC voltage to be dynamically stable. The main circuit parameters and control method are simulated by MATLAB/Simulink. The results validate the system design.
Highly sensitive humidity sensor based on ultra-long-period fiber gratings with asymmetric refractive index modulation
Y. Song, T. Zhu, Y. J. Rao, et al.
An Ultra-long-period fiber grating (ULPFG) with asymmetric refractive index modulation is fabricated in standard telecommunication optical fiber by using high-frequency CO2 laser pulses. A highly sensitive humidity sensor based on this grating can be realized due to its high refractive index sensitivity. The ULPFG is coated with a new nano-composite hydrogel material that has a strong water absorption capacity. This kind of hydrogel can absorb water vapor in the air substantially to make its own refractive index change, inducing the resonant peak shift of the ULPFG to realize the humidity measurement. The experimental results show that a resonant peak shift of ~30nm corresponding to a variation of the surrounding humidity in the range of 38%~96%, which is three times higher than that of the humidity sensors reported. Such a novel humidity sensor could find important applications in humidity measurement.
SFDM/CWDM of hollow-core photonic crystal fiber based etalon strain sensors with long cavity lengths
Y. J. Rao, D. W. Duan, T. Zhu, et al.
Spatial-frequency division multiplexing (SFDM)/coarse-wavelength division multiplexing (CWDM) of in-line fiber-optic etalon (ILFE) strain sensors, formed by a section of hollow-core photonic crystal fiber (HCPCF), is reported in this paper, for the first time to the best of our knowledge. Due to the low thermal expansion coefficient of HCPCF, such a strain sensor is much less sensitive to temperature change compared with conventional ILFE sensors. In the meanwhile, as the transmission loss of HCPCF is very low, the cavity length of the HCPCF sensor can be much longer than existing ILFEs, making it ideal for use in SFDM and offering great potential to realize multiplexing of a very large number of ILFE sensors. A SFDM/CWDM system with four HCPCF-based ILFE strain sensors is demonstrated and the experimental results show that a strain accuracy of ±5 can be achieved.
Signal and Image Processing
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High precision angle calibration of robotic total stations and laser trackers
D. Martin, D. G. Chetwynd
This paper presents the recent development of two angle standards, referred to as the Horizontal Circle Comparator (HCC) and the Vertical Circle Comparator (VCC), used in the calibration of high precision spherical measurement systems; a family of instruments consisting of robotic total stations (RTSs), and laser trackers (LTs). The paper discusses these standards and their utilization and then presents the first results of instrument calibrations with them.
Study of the characteristic of the penalty function in point cloud data's smoothing based on anisotropic heat conduction principle
Xuechang Zhang, Zhixin Jia, Meijuan Xu, et al.
It is necessary to smooth the point cloud data in reverse engineering or freeform surface inspection. The smoothing method based on the heat diffusion has a good effect to the point cloud with noise points, but how to choose a proper penalty function to smooth the point cloud is no answer. The paper proposes a method to decide the penalty function based on the fuzzy mathematics' relevant function concept. The four special functions, such as rectangular distribution, drop hemi- distribution, drop hemi-normal distribution and drop hemi-Cauchy distribution, have been analyzed. Each penalty function has been used to smooth the point cloud by experiment, the result show that drop hemi-Cauchy function and drop hemi-normal function are fit to be the penalty function. The conclusion is gotten that the variant has a no-linear relationship with the result of penalty function. Some cases are used to validate the characteristics of penalty function. There is a new way to handle the point cloud during the preprocessing of reverse engineering or complex surface inspection.
Three-dimensional object recognition based on 3D invariance
This paper presents a method based on 3D invariant features for the recognition of three-dimensional object. In this method, the projective invariant features are adopted as the representative of the 3D invariance. 3D invariant features are the features that will not change with viewpoints or poses, so they can be used to recognize three-dimensional objects. Exact point-line matching is achieved in use of the point-line characteristics obtained. On this basis, the views relation is established by the 2D projective transformation, and many kinds of 3D invariant features of complicated spatial structures can be neatly extracted by combining real elements and virtual elements. Therefore the three-dimensional object can be recognized. The results indicate that the method could greatly satisfy three-dimensional object recognition.
Extraction of shaft-rate modulated electric fields of a ship in shallow sea with strong background noise
Bin Shen, Shen-guang Gong, Xin-qin Chen, et al.
The electric field is the intrinsic characteristic of a ship. The measurement of the electric field of a ship is greatly disturbed by noise in shallow sea. The measured signals can be processed using wavelet transform, adaptive filtering or time-frequency analysis. Adaptive filtering can be used to remove a part of ambient noise. But the filtering effect is not obvious because a certain type of industrial interference signal is also of an extremely low frequency, When wavelet transform is used to remove noise, most noises from the electric fields of sea are removed. However, it also has nothing to do with the periodical noises with an extremely low frequency. As far as time frequency method is concerned, the original signals are first analyzed within the frequency band, and then they are compared with the measured ambient signals. After the range of shaft-modulated signals are found, the signals of required frequency band are extracted for further IFFT transform. The processing results show that the traffic characteristic of a ship is very clear, representing the signals are extracted out.
Application of Hilbert-Huang transformation to fault diagnosis of rotary machinery
Feng Chen, Xiang Zhou, Qinghua Wu, et al.
The vibration signal of a rotor bearing system is usually nonlinear and non-stationary. Fourier transform is hard to analyze these signals. A new method based upon empirical mode decomposition (EMD) and Hilbert spectrum is proposed for fault diagnosis of roller bearings. We get vibration signals from 6205-type ball bearings with inner-race faults and with outer-race faults, then analyzing its local Hilbert spectrum and local Hilbert marginal spectrum. Comparing the results with theory value, we can diagnose the fault of rotary machinery fault. In this study, we find that local Hilbert spectrum and local Hilbert marginal spectrum are very useful. Hilbert Transformation is introduced to confirm the HHT method is fit to process nonlinear and non-stationary signals.
Underdetermined blind mixing model recovery using differential evolution and Hough transformation
Ning Fu, Guangquan Zhao, Xiyuan Peng
Underdetermined blind mixing model recovery (UBMMR) is one of the most important steps in separating underdetermined blind sources, which has a direct effect on the recovery accuracy of source signals. A new blind mixing model recovery algorithm is proposed, under the assumption that the sources are sparse. The mixture data observed are first allocated to several clusters using the partitional clustering algorithm based on differential evolution (DE). The cluster centers are amended through Hough transformation to recover the mixing model. The peak clustering problem in Hough transformation is successfully avoided at the same time. Experimental results show that the proposed algorithm has advantages of high robustness and accuracy compared with conventional algorithms.
Enhancement of infrared image using fractal based human visual system
Tian-he Yu, Jing-min Dai, Wei-min Kang
This paper presents a fractal based human visual system(HVS) proposed for elimination of blurred edge and enhancement of infrared images. Human visual system is used in the proposed approach and the fractal dimension of an infrared image is first measured using a fraction Brownian motion model as an accurate indication of the coarseness of an infrared image. The fractal dimension of each pixel was calculated using a fractional Brownian random model and the self-similitude and surface coarseness of the gray level of each pixel are described using fractal value of each pixel. HVS is sensitive to the edge area of an image, and the pixels are then classified into edge pixels, smooth pixels and texture pixels according to their fractal dimensions. The gray level of each edge pixel is weighted and enhanced using a fractal based HVS. Experimental results indicate that fractional Brownian motion model is effective in detecting the edge detail of an infrared image. This approach can be used to preserve edge details and enhance the contrast of an image.
A new local search method to design finite precision FIR filters
Yi-Cheng Zeng, Shu-Hua Li, Mao-Lin Xu
This paper proposes a new local search method for the design of FIR filters with low complexity finite precision coefficients based on the optimality criterion of peak constrained least squares. In order to improve search efficient and reduce invalid search steps, the proposed method adjusts the coefficient offsetting strategy conditionally and utilizes the geometric properties of the object function &Egr;(h) that describes a hyper-ellipse. If the search point is inside &Egr;(h) , it is selected, so the search trapped in an infeasible region is avoided. The tradeoff between coefficient complexity and PSR is got. Numerical experiments show that the proposed method holds better performance than the existed methods in terms of the search efficiency.
Research on classifying technique for imbalanced dataset based on Support Vector Machines
Zhi-ming Yang, Yu Peng, Xi-yuan Peng
It is shown that SVM can be ineffective in classifying the minority samples, when it is applied to the problem of learning from imbalanced datasets. To remedy this problem, this paper analyzes the true reason of negative effect to SVM classifier caused by data imbalance firstly. Based on this, a new method of shifting classifying hyperplane in the feature space is proposed, and its implementation method-Boundary Movement based on Sample Cutting Technique (BMSCT) is also described. Through theoretical analysis and empirical study, we show that our method augments the classification accuracy rate effectively without increasing the computation complexity.
Fast centroid estimation algorithm for coordinates measurement of infrared markers
Lingfei Zhang, Gang Chen, Dong Ye, et al.
To determine the coordinates of infrared markers, it is very important for the binocular vision system based on lightweighted passive infrared reflective markers and infrared LED array PCB board, which is often used to measure the 3-D motion parameters of a rocket motor. Therefore, a fast centroid estimation algorithm, which segments the infrared image using self-adapting thresholding method, and then the centroid of infrared markers is calculated using improved statistical averaging technique, was developed. A comparison was made between the newly developed algorithm and other algorithms such as traditional statistical averaging, FFT and least-squares method. It is found through comparison that the new algorithm is more suitable for high-speed motion analysis due to its higher accuracy and faster processing speed. Experiments performed on real-world images show that the algorithm can greatly improve the speed of the calculation and meantime ensure the demand of precision on the basis of the better image segmentation result and improved statistical averaging technique.3
Multi-channel high-speed CMOS image acquisition and pre-processing system
Chun-feng Sun, Feng Yuan, Zhen-liang Ding
A new multi-channel high-speed CMOS image acquisition and pre-processing system is designed to realize the image acquisition, data transmission, time sequential control and simple image processing by high-speed CMOS image sensor. The modular structure design, LVDS and ping-pong cache techniques used during the designed image data acquisition sub-system design ensure the real-time data acquisition and transmission. Furthermore, a new histogram equalization algorithm of adaptive threshold value based on the reassignment of redundant gray level is incorporated in the image preprocessing module of FPGA. The iterative method is used in the course of setting threshold value, and a redundant graylevel is redistributed rationally according to the proportional gray level interval. The over-enhancement of background is restrained and the feasibility of mergence of foreground details is reduced. The experimental certificates show that the system can be used to realize the image acquisition, transmission, memory and pre-processing to 590MPixels/s data size, and make for the design and realization of the subsequent system.
Measuring accuracy of temperature dependence on thermal emissivity in flame
Shouzhi Xia, Yan Guo, Xinwang Zhu, et al.
Some factors were analyzed that thermal emissivity of gray-body were brought change in this paper such as wavelength and temperature and absorbing spectrum and emissive spectrum and the surface characteristic in flame. Based on the thermal radiation theory of gray-body, the emissivity function theoretic model of the burning object was presented. Different approximation schemes were adopted according to the property of combustion production, the equation was set up in combustion field. The influence of the measuring temperature accuracy to the emissivity precision was developed in flame. The results shows the object in flame can be divided into three kinds of gray body, the correlative emissivity variable need adopt different approximation technique, a method for temperature and emissivity measurement by multi-wavelength can improve efficient the measuring precision.
Research on steel ball surface quality detection technique based on CCD
Lihua Liu, Huiping Ma, Yunyan Ma, et al.
The system of steel ball surface quality detection based on CCD is designed and operating principle is analyzed in this paper. An in-depth study on illuminating system, detecting environment and image processing is presented. According to reflected light characteristics of steel ball surface, the illuminating project of point light source scattering is presented, which can avoid losing original information. Image processing order, step and concrete algorithm are designed and researched based on image identification technique and corresponding software is designed. Repeatability and precision testing is put forward and the main cause of error is analyzed. The testing results indicate that the detection system can meet the design requirement."
Measurement of micro-hole with high aspect ratio by double optical fibers coupling
Jiwen Cui, Jiubin Tan, Fei Wang, et al.
In order to measure the geometry of a micro-hole with high aspect ratio, we made the light coming out from the laser to transmit in the reversal direction by double optical fibers coupling, modeled both the energy distribution at the end of an optical fiber and the output of CCD, used zernike moment subpixel algorithm to locate the edge of an image and a compensation algorithm to improve the precision of edge location. The effectiveness of the method newly developed is verified through experiments. Experimental results indicate that the newly developed method can be used to measure the geometry of a blind hole of 2.0mm depth with a diameter of about 0.2mm using a double frequency interferometer with a repeatability uncertainty of less than 0.4m.
Automated detection of pulmonary nodules in CT images with support vector machines
Lu Liu, Wanyu Liu, Xiaoming Sun
Many methods have been proposed to avoid radiologists fail to diagnose small pulmonary nodules. Recently, support vector machines (SVMs) had received an increasing attention for pattern recognition. In this paper, we present a computerized system aimed at pulmonary nodules detection; it identifies the lung field, extracts a set of candidate regions with a high sensitivity ratio and then classifies candidates by the use of SVMs. The Computer Aided Diagnosis (CAD) system presented in this paper supports the diagnosis of pulmonary nodules from Computed Tomography (CT) images as inflammation, tuberculoma, granuloma..sclerosing hemangioma, and malignant tumor. Five texture feature sets were extracted for each lesion, while a genetic algorithm based feature selection method was applied to identify the most robust features. The selected feature set was fed into an ensemble of SVMs classifiers. The achieved classification performance was 100%, 92.75% and 90.23% in the training, validation and testing set, respectively. It is concluded that computerized analysis of medical images in combination with artificial intelligence can be used in clinical practice and may contribute to more efficient diagnosis.
Region-based image denoising through wavelet and fast discrete curvelet transform
Yanfeng Gu, Yan Guo, Xing Liu, et al.
Image denoising always is one of important research topics in the image processing field. In this paper, fast discrete curvelet transform (FDCT) and undecimated wavelet transform (UDWT) are proposed for image denoising. A noisy image is first denoised by FDCT and UDWT separately. The whole image space is then divided into edge region and non-edge regions. After that, wavelet transform is performed on the images denoised by FDCT and UDWT respectively. Finally, the resultant image is fused through using both of edge region wavelet cofficients of the image denoised by FDCT and non-edge region wavelet cofficients of the image denoised by UDWT. The proposed method is validated through numerical experiments conducted on standard test images. The experimental results show that the proposed algorithm outperforms wavelet-based and curvelet-based image denoising methods and preserve linear features well.
Application of adaptive wavelet transforms via lifting in image data compression
Shujiang Ye, Ye Zhang, Baisen Liu
The adaptive wavelet transforms via lifting is proposed. In the transform, update filter is selected by the signal's character. Perfect reconstruction is possible without any overhead cost. To make sure the system's stability, in the lifting scheme of adaptive wavelet, update step is placed before prediction step. The Adaptive wavelet transforms via lifting is benefit for the image compression, because of the high stability, the small coefficients of high frequency parts, and the perfect reconstruction. With the adaptive wavelet transforms via lifting and the SPIHT, the image compression is realized in this paper, and the result is pleasant.
Cooperative optimization and their application in LDPC codes
Ke Chen, Jian Rong, Xiaochun Zhong
Cooperative optimization is a new way for finding global optima of complicated functions of many variables. The proposed algorithm is a class of message passing algorithms and has solid theory foundations. It can achieve good coding gains over the sum-product algorithm for LDPC codes. For (6561, 4096) LDPC codes, the proposed algorithm can achieve 2.0 dB gains over the sum-product algorithm at BER of 4×10-7. The decoding complexity of the proposed algorithm is lower than the sum-product algorithm can do; furthermore, the former can achieve much lower error floor than the latter can do after the Eb / No is higher than 1.8 dB.
Extraction of lane markings based on steerable filters
Yanbing Liu, Jian Rong, Ke Chen
Determination of lane position is an important component in the driver-assistance systems to provide meaningful and consistent road shape information for navigation purpose. Extraction of lane markings is a key component to detection of lane position. In this paper, we propose a new algorithm for extraction of lane markings based on steerable filters, which have been used to analyze local orientation patterns in imagery. Steerable filters are efficient for extraction of lane markings because by computing only three separable convolutions, we can extract a wide variety of lane markings. The steerable filters used for detection of lane are based on second derivatives of two-dimensional Gaussians. Such filters based on even-order derivatives are symmetric. While symmetry produces orientation responses that are periodic with period , independent of image structure, we present a more general asymmetric steerable function that alleviates this problem. The algorithm is able to provide robust and accurate extraction of lane markings under varying lighting and road conditions.
Squared gray weighted centroid algorithm based on bi-cubic interpolation
Changying Liu, Yinhan Gao, Yong Zhang
A squared gray weighted centroid algorithm based on bi-cubic interpolation is proposed to solve the question of the optical feature precision location in the vision measurement. The location method makes full use of the gray information of feature image and uses the squared gray as weight to increase the function of pixels with higher gray value. At the same time, the bi-cubic interpolation algorithm is used to increase the available pixels to improve the location accuracy. Experimental results show that the location repeatability was less than 0.011 pixels and the location errors were less than 0.01 pixels. The centroid location method has better location accuracy and could be used for the precision location of optical feature for the vision measurement.
Design and simulation of turbine impeller in hydrovalve
The water level in refrigerator must be controlled accurately in order to adjust the refrigerator's temperature, namely, a flow sensor needs to be designed to precisely measure the water flow into the flume according to the structure of hydrovalve. So the mechanical model of the turbine impeller's vane was first done through the analysis of the vane's beard driving and dragging force torques, and the instrument constant of the flow sensor was deducted, the dynamic measurement characteristics of the flow sensor was then analyzed to analyze the measurement precision of the flow sensor. The structure of flow sensor has been designed according to the results of theoretical analysis, and the flow field simulation of the turbine flowmeter has been done using the software of FLUENT. The theoretical and experimental results show that the mechanical model of the turbine flowmeter is reasonable and the mathematical expression of the ideal instrument constant can be adopted as the design reference of the flow sensor.
Applied strategy for options of invasive and non-invasive sensors and instruments
Zhang Yan, Liu Xin, Fabio Scopesi, et al.
A diverse range of sensors and instruments is available for use in the critical care of acutely ill patients and it is not always straightforward to decide which technologies should be used. Clinicians have their own priorities for the physiological variables that they consider need to be monitored in order to provide optimum medical care. Alongside this, consideration must be given to the choice of available technologies. This choice may be influenced by performance criteria, cost, and ease of use. It is also necessary to consider the physical status of the patients, the measurement instruments and any potential risks for the patients so as to provide the best measurement scheme. This paper explores the use of decision support tools that may be used in critical care situations. The care of ill newborn babies requiring mechanical ventilation is considered as a case study. The choice of invasive and non-invasive techniques for blood gas and pH assessment is evaluated and decision trees and hierarchical clustering are considered as possible decision support methodologies.
Phase shift error of dynamic spectrum
The phase shift error (PSE) for DS detection is analyzed using frequency domain measure theory of DS. Two factors lead to the difference among different pulse waves, and introduce PSE into DS. Firstly, the period, amplitude and the base line of pulse wave are unstable. Secondly, the phases of pulse waves under different wavelengths are different. The PSE of transmitted and reflected pulse waves are both discussed quantitatively. The results showed that the PSE is correlated with the position of rectangular intercept window that intercepts pulses from the waves. It can be minimized into about 10% by selecting the start points of the windows. Because of the sensor contact pressure, the shapes of transmitted and reflected pulse waves are different. Thus the right intercept locations are at the start of ascending limb and the dicroticpulse respectively according to minimum PSE rule.
CARS application in measurement of flame temperature
Hu Zhang, Jing-min Dai
Flame temperature distribution is very important for combustion diagnosis, but it is very hard to measure it because of the instability of flame and possible transient variability. Classical method used for measurement of flame temperature is always a contact method utilizing a thermocouple. Limitations on the use of thermocouples include long response time, disturbance on target temperature field, inelasiticity in rigorous measurement circumstance. Only coarse qualitative results can be acquired. A potential laser spectrum diagnostic technology was therefore introduced. The method of coherent anti-stokes Raman spectroscopy (CARS) in the measurement of temperature distribution was discussed using CARS theory. The design of measurement system was put forward and preliminary experiment results are shown. Theoretical CARS spectrums at 2000K were calculated utilizing the model of molecule transition in CARS process. Experimental results were compared to those of thermocouple measurement, and since results of two methods are close, feasibility of CARS application in the measurement of flame temperature was verified. Although the resolution of this method is not applicable for real-time measurement, a single measurement can be accomplished in a few nanoseconds. The resolution of temperature measurement is 5% better than results of measurement by thermocouple. Furthermore, future research is suggested to overcome the insufficiency of this method was pointed out with direction suggested.
Electromagnetic Measurement and Automated Testing
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Simulation of radar antenna scan and design of hardware
Wang Xu, Jianmao Xu, Gang Xi, et al.
An antenna scan simulator has been developed for the real time radar electromagnetic environment simulation. The simulator is composed of man machine interface, digital compensation control, attenuation of high dynamic range, temperature compensate, wideband pulse modulator and power amplifier. The variations of gain of different antenna scans are pre-computed and stored as a data table in the simulator. After the parameters of antenna scan are set through the man machine interface, the values of amplitude attenuation can be acquired by table lookup and is transferred to digital compensation control. Then the attenuation module varies the radio signal with time, which is realized by integrated digital attenuator and PIN diode. Temperature compensate maintains the temperature error of power in a certain design range. Wideband pulse modulator can make continuous wave or wide pulse modulated signal into narrow pulse modulated signal. Finally, a power amplifier is used to compensate the insertion loss. The simulator can be connected directly to the commercial microwave signal generator to offer a comparative real antenna scan signal.
Measurement of shaft-rate modulated electric fields of a ship in a shallow sea
Bin Shen, Shen-guang Gong, Xin-qin Chen, et al.
As an intrinsic characteristic, the shaft-rate modulated electric field of a ship is an important signal source in underwater domain. A measurement system is designed to measure the shaft-rate modulated electric field of a ship. Taking into consideration the pressure bearing, watertightness and other problems, the system is made up of sensors, signal condition circuits, and data acquisition and processing system. After the measurement system is sunk down to the seabed, it is difficult to regulate orientation, attitude and other sensor parameters. It is also hard to control the environment around the system. Therefore, the status information of the seabed is recorded for posterior calibration. Frequency analysis and time-frequency analysis methods are used for signal processing. Experiment results show that the spatial distribution of shaft-rate modulated electric field has a significant regional property and apparent traffic characteristic.
Test scheduling of system on chip for crosstalk effects on core interconnects
Zhongliang Pan, Yihui Chen, Ling Chen
Test scheduling is an important task for the test of a system on chip, and it determines the assignment of cores to the test access mechanism such that the overall test time is minimized. A new test scheduling approach based on cultural algorithms for system on chip is presented in this paper. First of all, the optimization model of test scheduling is given, the model uses the information such as the bits width of the test access mechanism and the scale of test sets of cores, the crosstalk fault test sets of core interconnect lines is also discussed. Secondly, a method based on cultural algorithms is proposed to solve the optimization model of test scheduling. The ant colony algorithm is used in the population space, and the conventional genetic algorithm is used in the belief space. The feasible solutions of test scheduling are represented by individuals, a lot of individuals form the populations. The optimal test scheduling scheme is obtained by the evolution of the populations. Experimental results on a lot of benchmark circuits show that the proposed approach in this paper can solve the problem of test scheduling effectively.
Design of differential-switched-capacitor vortex flowmeter
Yu Zhang, Jingmin Dai
The structure of DSC has a high vibration resistance and a high temperature resistance(up to 400..) and so, a DSC sensor is adopted in the design of a vortex flowmeter, which is mainly comprised of a movable electrode and two fixed electrodes. The movable electrode of DSC is a hollow cylinder and the fixed electrodes are two metal films symmetrically plated on a dielectric cylinder. The air between the movable electrode and the fixed electrodes is the medium of DSC. A Simplified Model is established to research the operation principle of Differential-Switched- Capacitor. Based on the characteristics of vortices, a Differential Switched-Capacitor Converter is adopted, which utilize a electronic analog switch to complete the charge and discharge of the two capacitors alternatively under the control of a clock signal to convert the capacitance signal of DSC into a voltage signal. Experiments are performed on water medium in a pipe of 25mm in nominal diameter. Five calibration points are selected and three tests are performed of each calibration points. Experimental results show that the accuracy of DSC vortex flowmeter is 0.62% and the repeatability error is 0.16%.
Laser Measurement Techniques and Instruments
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In-line fiber-optic Fabry-Perot refractive-index tip sensors
Yun-Jiang Rao
We propose and demonstrate two novel in-line fiber-optic tip sensors for practical refractive-index (RI) measurement, which are based on an intrinsic Fabry-Perot interferometer (IFPI) formed by a section of conventional single-mode fiber or endlessly single-mode photonic crystal fiber (EPCF), respectively. Such an IFPI sensor has the advantages of easy fabrication, low joint and transmission losses, low-cost and good fringe visibility. Simultaneous measurement of RI and temperature can be realized by determination of the cavity length change and the fringe visibility of such an IFPI, respectively. In addition, it is found that the fringe visibility of the IFPI is insensitive to temperature change, providing a practical way to measure refractive index with self temperature compensation and offers a refractive-index resolution of ~10-5 in its linear operating range. The experimental data agree well with the theoretical results.
Precision inspection of diameters for circular reflecting cylinders
The urgent problem for industrial inspection is non-contact precision measurement the diameters of circular reflecting cylinders, namely, rolling bearing elements with diameter from 10 mm to 50 mm must be inspected with error no more than 1 ìm. Diffraction method for measurement of diameters of circular reflecting cylinders is presented. Peculiarity of this method is rather measurement gaps between two cylinder vertexes and two reference half-planes, than measurement of cylinder diameter by direct Fraunhofer method. Equivalent model of formation of Fraunhofer diffraction pattern by measurable object is developed. Using this model an algorithm of diffraction pattern processing was suggested that allows determining gap between object edges and reference half-planes with error no more than 1ìm.
Application of superresolution technology in non-contact measurement on edge detection of precise parts
Hong Lu, Bo Lei, Jae-Youn Jung
The precision of traditional methods of edge detection of precise Parts with linear CCD only reach &mgr;m because of the size of CCD cells. A sup-pixel edge detection method of CCD based on least square method and derivative operator method is proposed to improve the measurement precision. The Image Gradient obtained using derivative operator method. Point A with the max Gradient is then regarded as the point of the edge, and then the pixels nearby edge are interpolated linearly. For example, a high-speed data acquisition system is designed using high accuracy linear CCD TCD1501D and high speed A/D converter TLC5510. Experimental results show that the resolution &mgr; of the system design is 0.02pixel and the measurement precision is improved by one order of magnitude over traditional methods of edge detection.
A laser measurement system with multi-degree-of-freedom
A new five-degree-of-freedom measuring system was developed as a linear guide. According to the principle of autocollimation, the system consisted of two semiconductor lasers, two right angle prisms, two lenses, two polarization spectroscopes and four quadrant Si-photoelectric detectors(QPD). Two axial displacements and three angular rotation degrees are measured by comparing the position of the spot center on the QPD. Repetitive simulations show that the accuracy of the system is 3" for measurement of angle, which proves the feasibility of this system. The advantages of the system include simple structure, easy operation, high accuracy, low cost and real-time work.
Observation of single- and two-photon luminescence on optically quenched wide-gap semiconductor crystals
A. S. M. Noor, M. Torizawa, A. Miyakawa, et al.
Simultaneous observation of quenched wide-gap semiconductor crystals has been observed using single- and two-photon luminescence. It is was found at the quenched area, single-photon excitation gives luminescence read-out compared to two-photon which no luminescence detected at the bandgap wavelength. This is due to transition of electron between the bandgap in the two-photon luminescence to occur have been demolished by the quenching which involved two-photon quenching process. Furthermore, side lobes that exist in the longer part of the luminescence spectrum are resulted by decreasing in the Stark effect which increased the transition energy. The dependency if excitation power with the observed from the crystal's luminescence is elaborated which confirmed the single- and two-photon luminescence methods.
Parallel laser ranging technology of array type
Mudi Xiong, Rongfang Zhao, Aixia Zhou
The paper presents a new parallel laser ranging technology of array type which adopts multi-channel frequency division multiplexing modulation to realize multi-point synchronous measurement. The DDS (direct digital synthesis) technology is used to produce the parallel sine wave signals needed to realize frequency division multiplexing modulation on the lasers of array. The signals are produced by DDS chips under the control of DSP processor. Because phase has a great effect on the measurement precision of the system and the commonly used digital phase detection method - FFT algorithm has its own drawbacks, such as spectral leakage, "non-synchronous sampling" etc. which cause errors, so the all-phase FFT is introduced here to remedy these defects. The phase- spectrum value at main spectral line can be directly viewed as the original phase without any correcting measures. The paper elaborates the realization of parallel laser modulation, laser detecting, mixing, synchronous sampling and high-accuracy phase detection using this technology, analyzes the factors which cause errors. The results of preliminary experiment and simulation indicate that the parallel laser ranging technology of array type could be used to realize high-speed high-accuracy parallel measurement.
Laser precision ranger based on beat-wave interferometry
Tao Zhang, Yanhua Wu, Huang Weia
This paper presents a laser precision ranger based on beat wave interferometry. A frequency-stabilized double longitudinal modes He-Ne laser with thermoregulation is used as the light source. The two beams of double longitudinal modes generated in the same resonator of the laser are naturally coaxial. They have a frequency difference of about 790MHz and a beat wavelength of 380mm. Their stability is the same as the laser, which is better than 10-7 in open air. The node of the beat wave is used as the sampling flag. An adaptive filter and a wavelet transform program are used to eliminate the noise and to improve the accuracy of node detection. The distance between the node and the measur ed point is measured with a double frequency interferometer, which is incorporated in the same optical system and has a resolution of 0.08&mgr;m. Experimental results indicate that the measuring range is 20m and the uncertainty 30&mgr;m /10m.
Observation of dust aerosol profile and atmospheric visibility of Xi'an with Mie scattering lidar
Dust aerosol or sand storm has become the popular attention topic of the world currently. In order to understand and study the aerosol optical properties, particularly for dust aerosol produced in the spring weather condition, and to investigate their effects on atmospheric pollution status, a Mie scattering lidar was developed to detect the time and spatial distribution of the aerosol and the atmospheric visibility at Xi'an, China. The lidar system employs a Nd:YAG pulsed laser at a eye-safe wavelength of 355nm as a transmitter, and a Schmidt-Cassegrain telescope as a receiver. A spectroscope filter combined with a high-resolution grating was used to separate the main lidar returns and to block the solar background simultaneously for daytime measurement. The observation experiments with lidar have been carried out from the spring of 2007. The data of the extinction coefficients of aerosol and atmospheric visibility taken under the different atmospheric conditions are demonstrated. The comparison results of visibility measurement using lidar and other tool show that the lidar system is feasible, and the aerosol observation results show that the main aerosol pollution of Xi'an is from the floating dust aerosol, which is usually suspended at a height of near 1km.
Orthogonally polarized lasers' semi-classical theory for tuning inner cavity and external cavity
Liu Cui, Shulian Zhang, Xiaobin Zong
Plenty of novel characteristics have been observed during inner-cavity and external cavity tuning in the orthogonally polarized lasers which has attracted the interest of many researchers and been applied as sensors to measure angles, displacements, wave plates' retardation, etc, and are often more accurate and affordable than currently available interferometers or inductance transducers. However, effective theory models to explain the orthogonally polarized lasers' characteristics are still hitherto unknown. In this paper, the inner-cavity and external cavity intensity tuning characters of orthogonally polarized lasers with different parameters are studied, respectively. First, we discuss the semi-classical theory model of orthogonally polarized laser based on the vectorial extension of Lamb's theory, and are compared with the experimental results for tuning inner-cavity. Then the thought of multiple-beam interference is introduced to extend the theory model to solve the problem of multiple feedback effects which appear as the external cavity is tuned in the orthogonally polarized lasers and the experimental results agree well with theoretical analysis.
High-resolution compact displacement sensor based on anisotropic feedback of microchip Nd:YAG lasers
Yidong Tan, Shulian Zhang
A simple and effective displacement sensor based on external anisotropic feedback in Nd:YAG lasers has been presented and demonstrated. When the system operates in anisotropic feedback induced by placing a birefringence element with phase difference about 45 degree(such as a wave plate) in the external cavity, both the laser intensities in two orthogonal directions are sinusoidal-modulated by the external reflector with a period of half wavelength displacement, but with a phase difference about 90 degree between them. When threshold intensity is introduced, a period of intensity fringe can be divided into four equal zones. Each zone corresponds to &lgr;/8 displacement of the external feedback reflector. According to the appearing sequence of the four states, the movement direction of external reflector can be discriminated. Thus, a novel displacement sensor with a resolution of up to 133 nm, as well as a function of direction discrimination, is believed to be achieved. The chief advantages of this sensor are that it is compact, small size, flexible, low cost, and robust. Most importantly, this sensor has a great potential to be improved in resolution by electric subdivision methods applied in the grating encoders. Experimental results have shown that the uncertainty (3&sgr;) of displacement measurement is 0.2&mgr;m in a 7mm range, and the linearity is better than 2.5710-5.
Design of intelligent receiver system for phase-shift laser range finder
Fang-xiu Jia, Zhen-Liang Ding, Feng Yuan
This paper presents the design of an intelligent receiver system based on DSP and Avalanche photodiode. A new method of changing the reverse bias voltage based on the real-time measured noise of the system is proposed to avoid the environment influence on the performance of APD and to obtain the optimal operating performance of the whole system. Both the reverse-biased voltage and the automatic gain control loop are adjusted together by DSP, and so the high SNR is achieved and reception light saturation is eliminated. Method of compensating the walk error based on the reflected signal amplitude is used to improve the precision of phase shift measurement. The laser range finder fitted with the newly designed system can get a dynamic range 1:1500 and a phase-shift measurement resolution better than 0.045°. The measured diatance resolution is 0.125mm when the modulation frequency is 150MHz.
Data fusion algorithm for high accuracy coordinate transformation
Jingliang Lv, Chunfu Zhang, Wenyan Tang
A new data fusion algorithm is proposed to improve the coordinate transformation while geometrical measurements are made using laser tracker together with multi-joint measuring arms. A target ball was used as the common point for the laser tracker to directly measure the central coordinate of the target ball, and the multi-joint measurement arms were used to indirectly measure the central coordinate of the target ball by measuring the surface of the target ball. A least square coordinate transformation model based on Cartesian coordinate difference was established,according to the principle of least distance residual error for the coordinates of common points before and after coordinate transformation. The effectiveness of this approach was verified through experiments. Several common points were located within the range of multi-joint measurement arms so that the laser tracker could also measure them in the same way, and consequently the fusion of data from the different apparatus could be realized. Experiment results showed that this data fusion algorithm was effective, feasible and exhibit higher calculation accuracy.
Investigation of diode-pumped 1064nm dual-frequency Nd:YAG laser with large frequency difference
Mingxing Jiao, Junhong Xing, Yun Liu, et al.
When a new birefringent filter consisting of a polarizing beam splitter (PBS) and a half wave-plate (&lgr;/2), i.e., PBS-&lgr;/2 was included in a 1064nm Nd:YAG laser cavity, the laser was enforced to oscillate in single longitudinal mode. The single longitudinal mode selecting ability of the intra-cavity filter of PBS-&lgr;/2 had been studied experimentally by rotating the half wave-plate around the laser cavity axis, and the tuning characteristics of the single-frequency laser output power versus the rotation angle of the half wave-plate had also been studied. An orthogonally and linearly polarized dual-frequency Nd:YAG laser at 1064nm had been designed and demonstrated, which included two standing-wave cavities sharing the same gain medium of Nd:YAG crystal and the birefringent filter of PBS-&lgr;/2, the p-and s-components of the 1064nm laser light simultaneously oscillated in single longitudinal mode in each cavity. The frequency-difference of the dual-frequency laser at 1064nm was measured to be approximately 1.87GHz, limited by the free spectral range of the scanning Fabry-Perot interferometer. It is predicted theoretically that the frequency-difference of the dual-frequency laser at 1064nm can be tuned in a range from zero up to the lasing bandwidth of the Nd:YAG laser.
Pavement roughness measurement based on structure light
WanYu Liu, Xiaoming Sun, Jian Ping Huang, et al.
Pavement roughness is an important index to reflect the quality of pavement. To improve the efficiency of pavement roughness measurement, a novel pavement roughness measurement system based on structured light vision inspection is proposed in this paper. By describing the principle of structured light inspection and measurement system design, it is stressed that the proposed system can be used to acquire a continuous longitudinal profile of pavement and International Roughness Index by using the structured light illumination and CCD. Some experiments are performed to test orientation precision and performance of the system. The experimental results show that the system has some pros such as high orientation precision, good stability and low cost.
Study on use of fiber Raman amplifier in U-band for gas detection
Lanlan Liu, Chongqing Wu, Guodong Lin, et al.
Most gases have their absorption peaks in the U-band, and so, we used ordinary single-mode fiber as the gain medium and a double-clad Er-Yb co-doped fiber laser as the pump source to set up a U-band 1665nm fiber Raman amplifier system for gas detection.
A fast and ultra-precision laser heterodyne interferometry signal processing method based on digital delay line loop
Lei Yan, Peng-cheng Hu, Xiao-fei Diao, et al.
To achieve higher dynamic resolution of laser heterodyne interferometry, a new signal processing method based on digital delay line technology is proposed. To implement ultra-multiple electronic subdivision, the multiple frequency of the reference signal which is generated from an analog phase-lock loop is passed through a multi-tap digital delay line. On every positive edge of the measurement signal, each tap of the delay line is captured and decoded to obtain the exact occurrence time. And according to the reference period, the system can also provide a real time output of the displacement results. Simulations and experiments show that using a laser heterodyne interferometry with its beat frequency of 1MHz, the system can provide a dynamic position resolution of 0.83nm at velocities up to 260mm/s by using a 64 multiple analog phase-lock loop and a 6-tap digital delay line, the update rate of the displacement positions is up to 100KHz.
Design of driving and control system based on Voice Coil Actuation for linear motion of micro-lens array
In order to realize laser beam steering, a driving and control system based on Voice Coil Actuator (VCA) is designed for linear motion of micro-lens array. According to the feedback displacement signals acquired from displacement sensor, controller of the system sends control signals to Purse Width Modulator (PWM) driver which is used to power the VCA. VCA provides driving force for the support structure of the system which connects the micro-lens array, and then the linear motion of micro-lens array is achieved with the movement of support structure. The effectiveness of the system was verified through experiment. Experiments results show that the displacement resolution of the linear driving and control system is 10&mgr;m , which satisfies the requirement for laser beam steering.
Distributed Bragg reflector fiber lasers for high temperature sensor applications
Bai-Ou Guan, Yang Zhang, Hong-Jun Wang, et al.
We present a high-temperature-resistant distributed Bragg reflector fiber laser photowritten in Er/Yb codoped fiber that is capable of long-term operating at 500°C. Highly saturated Bragg gratings are directly inscribed into the active fiber by use of the two-photon absorption at 193 nm. After annealing at elevated temperature, the stabilized gratings are strong enough for laser oscillation. The laser operates in robust single mode with output power more than 1 dBm and signal-tonoise ratio better than 70 dB over the entire temperature range from room temperature to 500°C.
Holography and Diffraction Optics and Instruments
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Application of diffractive optical elements for inspection of complicated through holes
Yuri V. Chugui, Yuri A. Lemeshko, Peter S. Zav'yalov
The inspection of geometrical parameters of through holes with different configurations is one of the urgent tasks in industry. The majority of the existing noncontact inspection methods doesn't allow measuring the holes of complicated (noncylindrical) configurations with good performances. Two simple developed methods based on diffractive optical elements (DOEs) make possible to inspect the through holes (with the diameter from 5 to 100 mm) both cylindrical and complicated configurations with acceptable lateral and axial (longitudinal) resolution. First method, based on the scanning of inner hole surface by light ring, takes a mechanical displacement of the inspected article along its axis. The second holes inspection method uses the DOE as the diffractive focuser, which generates N light rings simultaneously along the hole axis with ring spacing &Dgr;z. In this case no need for mechanical displacement of inspected articles, output image contains full measuring information about 3D article hole configuration. We have fabricated some binary DOEs using circular laser writing system CLWS-300, developed and produced at the TDI SIE SB RAS. The obtained results have been used under the development of universal automatic inspection system of nuclear reactors fuel assemblies spacer grids.
Computer generated holograms for aspheric optics testing
Paper presents the overview of the latest results of application of CGHs with more then 200 mm diameter and a minimum feature size of 0.5 micrometer for testing large aspheric surfaces with a Fizeau-type interferometer. Various experimental results are presented. Special attention was attended to the accuracy of adjusting the optical test system with the CGH and the problem of suppressing unwanted orders of diffraction. Designs of CGHs that can be used for optical alignment of complex optical systems are discussed.
Designing high efficiency uniform-intensity splitter with binary-phase subwavelength structure
Shuhua Yan, E. Li, Chun-lei Zhou, et al.
Dammann grating designed by using the scalar diffractive theory is a conventional uniform-intensity splitter with binaryphase, whose diffraction efficiency is no more than 87% generally and representative value is about percent 80. This will limit its further progress. Based on the rigorous couple-wave analysis theory and the genetic algorithm, a method has been proposed to design a new uniform-intensity splitter with binary-phase subwavelength structure, which has higher diffraction efficiency. Then five new-type beam splitters with binary-phase, whose splitting ratios are 3, 4, 5, 6 and 7, are obtained by the emulating package. Their diffraction efficiency is more than 92%, and it is very bigger than the conventional Dammann grating. Owing to its subwavelength structure, the size of this kind of splitter is smaller. It will be widely applied in some domains, such as ultra-precision manufacturing, micro-opto-electro-mechanical system, information processing, optical fiber communication, biomedicine, national defense, military affairs and entertainment, etc.
Thermal effects researching for laser microstructures synthesis by thermochemical circular laser writing
Features of thermal trace forming by thermochemical circular laser writing in chromium films on glass (quartz) substrates are considered on the basis of thermal equation system solution. Linear (thermal parameters do not dependence on temperature) and nonlinear (thermal parameters dependence on temperature) models are considered. It is showed that linear model is enough for thermal trace broads consideration. Calculation of thermal field is provided for wide range of linear scanning velocities (from 1.2 up to 9.4 m/sec). Dynamics of chromium film heating when laser beam is switched on is researched. Difference of the thermal trace form in switching on area and switching off area is showed. Also structures like chess board are synthesized for experimental investigation. Influence of thermal processes inertness on the broadband image parameters is considered on such samples experimentally. Recommendations for experimental selection of writing power have been done.
Fabrication of transmission gratings for extreme ultraviolet interference lithography
Jie Ma, Xiaoli Zhu, Weizhong Zhu, et al.
Transmission gratings with a period of 100 nm for extreme ultraviolet interference lithography are fabricated with 2 groups of 50 nm thick Cr bars on a 100 nm thick Si3N4 film. The fabrication process starts with depositing Si3N4 on both sides of (100) Si wafers by LPCVD, followed by electron beam lithography of ZEP520A resist, evaporation of Cr and resist lift-off. A 120 nm thick stop layer of Au is then evaporated onto the surrounding area to eliminate unwanted transmission. Finally, a pair of Si3N4 windows are opened on the back side by dry etching, and the Si under the grating pattern is removed by KOH anisotropic wet etching. Diffraction measurement shows an acceptable first order efficiency of the gratings at the wavelength of 13.4 nm. Using the fabricated gratings at the interference lithography beam line of Shanghai Synchrotron Radiation Facility, economic and efficient fabrication of gratings with a doubled pitch, namely 50 nm period gratings, can be expected.
Design of diffractive microlenses using general focal length function
Jie Lin, Jian Liu, Chenguang Zhao
In order to study the validity of general focal length function in designing diffractive microlenses with long focal depth, diffractive microlenses with different f-numbers are designed using general focal length function and their focusing characteristics, such as real focal depth, real focal spot size, and diffractive efficiency, are investigated using electromagnetic theory and boundary element method. Investigation results indicate that general focal length function can be used to achieve long focal depth in designing diffractive microlenses, even twice over than those of conventional diffractive microlenses with similar parameters.
Effect of tilted metallic mesh on modulation transfer function of optical system
Zhengang Lu, Zhigang Fan, Dandan Zheng
In order to analyze the effect of a tilted metallic mesh on the modulation transfer function (MTF) of an optical system, the relation between the MTF and tilted angle &ptheta; of the mesh was established through calculating the point spread function (PSF) of the tilted mesh using a model based on Huygens-Fresnel diffraction theory and then conducting Fourier transform on the calculated PSF. It was found through analyses that the density of triangular spikes on the MTF curve is compressed by 1/cos(&ptheta;) times along axis x, and the MTF values are degraded due to the stretch and asymmetrical distribution of diffraction spots of the tilted mesh; moreover, when the aperture of the mesh is so small that it is the optical stop itself, the cutoff frequency of MTF along axis x decreases by cos(&ptheta;) times and the MTF values drop largely. The degradation effect on MTF caused by a tilted mesh can be reduced by using a large-size metallic mesh and increasing the porosity ratio of metallic mesh.
Advanced Optics Measurement Techniques
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Absolute distance interferometry using diode lasers
An approach to a homodyne absolute distance interferometer (ADI) was previously presented which makes use of two extended cavity diode lasers (ECDL). The length measurement is performed by combining variable synthetic wavelength interferometry and two wavelength interferometry in one setup. In this contribution the ADI was compared to a counting HeNe laser interferometer up to a length of 10 m.
Form measurements by optical and tactile scanning
O. Jusko, M. Neugebauer, H. Reimann, et al.
The metrological concept and the optical probe system of the cylinder form coordinate measuring instrument (CMM) MFU110WP is described. Optical and tactile scanning form and position measurement data of a variety of standards and workpieces are discussed both in comparison to each other and to calibrated profiles of other measurement instruments. New scanning techniques like helical and spiral shaped scanning are presented.
Preliminary study on near-infrared spectroscopic measurement of urine hippuric acid for the screening of biological exposure index
Mitsuhiro Ogawa, Yasuhiro Yamakoshi, Kosuke Motoi, et al.
Biological Exposure Indices (BEIs) are reference for a chemical or its metabolite in the biological specimen. BEIs give guidelines for the evaluation of potential health hazards or for diagnosis of occupational illnesses. Among them, urine hippuric acid (HA) that is a metabolites of toluene is considered as the BEIs of toluene exposure for human and measured from workers using toluene. In this study, we attempted to develop a brief measurement of urine HA by using near-infrared spectroscopy. As the first step, water solutions of hippuric acid of several concentrations (0-250mg/dl) are measured. Afterward, artificial urines conditioned by adding glucose and urine to HA solutions were measured and analyzed. The solvents are optically measured within near infrared region (750-2500nm) obtaining optical absorption. Then, differential absorbance were calculated by subtraction of analyte absorbance from ion-exchange water absorbance and analyzed. As a result, for HA solutions, a calibration equation from absorbance in two wavelengths can be obtained by using multiple regression (R2=0.935). However, this calibration cannot provide a good estimation for artificial urines. Secondary, another calibration from three wavelengths was obtained and providing a good regression (R2=0.934). This result suggests that a brief urine constituents measurement using near-infrared spectroscopy can be developed.
Measurement of nano-particles size by evanescent interference field with conventional optical microscope
Xiang Yu, Yukihiro Araki, Kentaro Iwami, et al.
The size of a particle smaller than the diffraction limit is measured using a conventional optical microscope by adopting a standing wave evanescent field illumination. The scattering intensity from a nanoparticle is periodically modulated by shifting the intensity fringes of standing evanescent field. By measuring the intensity variation of scattered light during one cycle of modulation, particle sizes can be easily estimated. Furthermore, this technique has weak dependence on the material of particles. From the experimental result, the particle size ranging from 20 to 250 nm is successfully determined. This technique offers a low-cost size measurement for nanoparticles.
Near-field birefringence response of IPS liquid crystal thin film detected by Bi-SNOM
Dynamics information of nematic liquid crystal (NLC) in In-Plane-Switching (IPS) mode is attractive and important for applications of high vision angle techniques. In this paper, we used a novel evaluation method to detect the molecular orientation dynamics of NLC thin film in depth direction from its birefringence responses using birefringence scanning near-field optical microscopy (Bi-SNOM). In this method, a Bi-SNOM probe is inserted into IPS mode NLC thin film, in which the time responses of LC molecules at different position in depth are also measured. In addition, Molecular orientation hysteresis to the applied voltage is observed. We measured the orientation hysteresis of LC molecules at different position along the depth direction in the LC thin film. Experimental results show that the proposed method is effective and feasible for its consistence with original specialities.
Experimental study on measurement accuracy of hot disk thermal constants analyser
Qiang Wang, Jingmin Dai, Chunsuo Xin
This work aims at the improvement of measurement accuracy of thermal conductivity and thermal diffusivity using a hot disk thermal constants analyser. The hot disk technique is based on the transient heating of a double spiral plane sandwiched between two pieces of investigated material. By researching the temperature change in the sensor surface, it is possible to deduce both the thermal conductivity and thermal diffusivity of the surrounding material from one single transient recording, provided the heating power and measuring time are appropriately chosen within the reasonable range defined by the theory and experimental situation. Based on the engineering application requirement for precision and efficacy, a new experimental method has been developed for high-accuracy measurement of thermal conductivity and thermal diffusivity in different experimental conditions. The standardized material Pyroceram 9606, with a thermal conductivity of 4.05 W/(mK), has been investigated and analyzed using the newly developed method. The measurement results show that the precision 5% estimated for thermal conductivity and 4% for thermal diffusivity at or around room temperature and under normal pressure, which indicate that the newly developed method has led to the high-accuracy measurement of thermal conductivity and diffusivity.
Thermal expansion coefficient and electrical resistivity of nonuniform temperature specimen
Chunsuo Xin, Jingmin Dai, Qiang Wang, et al.
A new computing method is proposed for the measurement of the thermalphysical parameters of specimens with nonuniform temperature profile distributions. The calculation method is derived from the temperature dependence of the thermal properties, and can be applied to the measurement of the longitudinal thermal expansion coefficient and electrical resistivity. The cross section of the entire specimen is uniform at room temperature and the changes during the experiments are ignored in this method. If the temperatures are measured at equal intervals, the specimen may be considered as consisting of M equal segments and each of them is S long. The corresponding length and resistance of these segments at temperature T0 may be of any value. If the changes in length and temperature distribution of the specimen are measured, the temperature dependence of the thermal expansion coefficient can be worked out using this method. If the resistance and temperature distribution of the specimen are measured, the electrical resistivity versus temperature function of the specimen, which is corrected by thermal expansion, can be obtained as well. The validity of the computing method of thermal expansion coefficient and electrical resistivity is verified through computer simulation. The maximum 'measurement' error of electrical resistivity is 3.3%.
Measurement of surface temperature with thermal infrared imager
Yunhong Li, Xiaogang Sun, Guibin Yuan, et al.
A general computing formula has been formulated for the measurement of surface temperature and the corresponding relation between the thermal value and the true temperature of infrared images according to the principles of thermal radiation and temperature measurement with infrared thermal imager. A least squares method and an improved neuralnetwork method have been developed to calculate the temperature to diminish the deviation of neural-network method. The above two methods use the ratios among the three basic colors output from the thermal infrared imager as the independent variable or input variable, and can personalize the colorimetric temperature-measurement algorithm, so that the influence of emissivity, soot and combustion flame on the temperature result can be reduced. Simulation results show that the precision of these two methods are higher than that of the traditional neural network method. In addition, the precision of the proposed neural-network method is higher than that of the least squares method.
Precise optical measurement of surface contour of large paraboloid antenna
Long Shen, Zhenbang Gong, Liang Liu, et al.
A chord-angle method is proposed for the precise optical measurement of the surface contour of large and medium size paraboloid antenna. The possible errors of the proposed method are theoretically analyzed as a whole. The antenna surface measurement precision is controlled and adjusted by measuring the angle and chord length of the measuring target point on the antenna surface. The effectiveness of the proposed method is verified through measurements. Experimental results indicate that the chord-angle method is effective and it has wide application prospect. Compared to the conventional template method, this direct measurement method has higher precision and better applicability.
Full-field mapping of the stress-induced birefringence using a polarized low coherence interference microscope
Jenq-Shyong Chen, Yung-Kuo Huang
A polarization-sensitive optical coherence microscope (PS-OCM) has been developed to non-destructively measure birefringence distribution at the surface and internal interfaces of multi-layer structures. The PS-OCM can make twodimensional en face measurement by exploiting the parallel sensing capability of the CCD sensors. PS-OCM utilizes the low coherence interference principle to enable the depth-resolved mapping of the birefringence distribution inside the materials. By simultaneous detection of interference fringes in two orthogonal polarization states allows determination of the Strokes parameters of light. Comparison of the Strokes parameters of the incident state to that reflected light from the sample can yield a depth-resolved map of optical properties such as birefringence and refractive index. Because many semiconductor and optic materials such as ceramic/wafer/polymer/glass are stress-induced birefringence materials, changes in birefringence distribution may, for instance, indicate changes in material uniformity and stress inside the materials. The PS-OCM has the capability to measure the spatial stress-field distribution of a material caused by the residual stress or applied load. Using the high numerical aperture of the objective lens and the broad bandwidth of the light source, the PS-OCM has the 1.5micrometer and 1.6 micrometer resolutions respectively in the lateral direction and longitudinal (or depth) direction.
High accuracy measurements of long-term stability of material with PTB's Precision Interferometer
Demands on dimensional stability of 'high tech' materials relevant for semiconductor industry are growing considerably. Information about long term stability of materials could be extracted from high resolution length measurements performed within a relatively short time, e.g. using high finesse Fabry-Perot-resonators. However, the length changes observed during the short-term measurements can be overlapped by additional length relaxations induced by even small temperature changes before such measurement is started. This effect is reduced when long-term stability is studied from length measurements repeated in a larger period of time. This paper describes absolute length measurements with PTB's Precision Interferometer performed at four gauge block shaped material samples in order to extract reliable information about their long term stability. The long-term stability was found to be dependent not only on the material and its age itself but also on the material's history. The latter effect regards a one hour heating to 220°C applied to one of two identical sample bodies made of glass-ceramics which is still visible in the measurement results of long-term stability even after a period of almost seven years.
A time-resolved pump-probe system to study the dynamic excited-state nonlinearities of chloroaluminum phthalocyanine/ethanol solution based on the 4f nonlinear-imaging technique with a phase object
Dengke Hou, Junyi Yang, Yunbo Li, et al.
The 4f nonlinear-imaging technique with a phase object (NIT-PO) is a new method to measure the optical nonlinearity of materials by a single laser shot. A time-resolved pump-probe system based on this technique is constructed by introducing a pump beam with variable temporal delay, which can simultaneously measure the dynamic nonlinear absorption and refraction conveniently. Based on this system, we study the dynamic excited-state nonlinearities of the chloroaluminum phthalocyanine (CAP)/ethanol solution. Dynamic absorption coefficient and refractive index are deduced through analyzing frames of nonlinear image with different time delays from the standpoint of energy and the standpoint of information, and some photophysical parameters of the CAP are sequentially validated by theoretically fitting the experimental curves. On the other side it is demonstrated that the pump-probe system based on 4f NIT-PO plays a responsible role in simultaneously measuring the dynamic nonlinear absorption and refraction of materials, and the system could be a good tool for notarizing and characterizing the origins of optical nonlinearities within materials.
Effect of phase valley on diffraction efficiency of liquid crystal optical phased array
The discreteness of driving electrodes in liquid crystal optical phased array (LCOPA) device causes phase valley in the region between two adjacent electrodes. When a one-dimensional transmission-type LCOPA device was used, there was a pair of diffraction sidelobes with considerable intensity on either side of the deflected beam, which decreased the diffraction efficiency of deflected beam greatly. An analytical numerical model of phase valley was proposed for the quantitative analytic analysis on diffraction efficiency. Results showed that phase valley is the cause for diffraction sidelobes. The diffraction efficiency of deflected beam decreases steeply as the phase valley depth increases. When valley depth decreases close to zero, the main factor having affect on diffraction efficiency turns to be flyback region size. The influence of electrode space on diffraction efficiency was quantitatively analyzed as well. An effective way to reduce or even eliminate the phase valley is to reduce the space between electrodes.
Driving method to reduce data refresh rate in nematic liquid crystal optical phased array
The structure of a storage capacitor in nematic liquid crystal optical phased array causes the data refresh rate to be higher than the liquid crystal switching frequency, which demands a high data bandwidth. A novel driving method was therefore proposed to reduce the data refresh rate. Without using a storage capacitor, the proposed method uses digital scanning instead of conventional analog scanning. Furthermore, digital scanning is able to drive all pixels in parallel and transmit driver data only once for one frame. 1-D nematic liquid crystal optical phased array was used to test the novel driving method. During the experiment two frames of driver data were alternately transmitted at a refresh rate of 10 Hz, and diffraction patterns were acquired. Experimental results demonstrate that the proposed method can be used to keep the data refresh rate lower than the liquid crystal switching frequency.
Digital pinhole filter used for detection of confocal microscopy images
When conventional physical pinholes are used, the alignment of pinholes is always a problem. An iterative Wiener deconvolution filter is used to reject out-of-focus light, a sub-pixel centre location method is used to locate the centre of the pinhole, and the dimensions of the pinhole are optimized using the confocal microscopic theory. A filter with digital pinhole is thus developed and compared with filter with conventional physical pinhole through comparative tests. Experimental results indicate that the alignment of pinholes can be made easy, a filter with digital pinhole can be used to take place of a filter with conventional physical pinhole, and it can also reduce the pixel crosstalk resulting from multipoint illumination.
Improvement of lateral resolution property of differential confocal system using radial birefringent pupil filter
Li Min Zou, Xi Li, Hong Ji Zhang, et al.
Lateral resolution, as one of the most important parameters of a confocal system, has a direct effect on the measurement accuracy of a confocal system. The lateral resolution of a confocal system can be improved by introducing a radial birefringent pupil filter into a differential confocal system. The pupil function of this radial birefringent pupil filter can be obtained using Jones algorithm and, the angle between the polarization direction of the polarizing film of the lateral birefringent filter and the optical axis of the birefringent element, and the size of a filter a, can be got by analyzing the first zero point G. Meanwhile, we analyzed the influence of such factors as the defocusing amount on the lateral response of the system. It was proved through simulation and experiments that the lateral resolution of a confocal system can be improved using an optimized radial birefringent pupil filter.
High temperature (till 1500°C) contemporary thermal conductivity and thermal diffusivity measurements with the step flat heat source
Gianluigi Bovesecchi, Paolo Coppa
The method for contemporary measuring thermal conductivity, thermal diffusivity and thermal contact resistance up to 1500°C has been assessed. First the heat propagation model has been developed to be used in least square procedure to process temperature data and give the best estimate on the unknown parameters. Second special devices to be used in the experimental procedure have been designed and built or are going to be built. In the meanwhile ambient temperature tests on bricks have been carried out to establish the data processing procedure, and to recognize the experimental troubles likely to be found. These tests shows that the experimental data well follow the theoretical prediction, the thermophysical parameter can be evaluated with good accuracy, and that care must be taken to satisfying the theoretical assumptions on the base of the model, and to accurately process data for taking into account mutual dependence of the parameters.
Form measurement of small cylindrical objects using two-wavelength interferometry
A. Höink, K. Meiners-Hagen, O. Jusko, et al.
Form measurements of cylindrical objects are commonly done by mechanical sensing of the rotated specimen by a stylus. The needed probing force could cause a deformation or an abrasion of the specimen. A new interferometric measurement technique for form measurements of cylindrical objects with diameters between 0.1 and 2.5 mm is presented. In this technique the specimen is measured contactless and no rotary table is needed. The specimen is placed in the centre of an inverse conic mirror and is illuminated by an iodine-stabilized diode laser. The reflected light is superposed under a slight angle with a reference beam and imaged on a CCD camera. The surface topography of the specimen can be derived from the reconstructed spatial phase distribution, which is calculated by a spatial phase shifting algorithm. In order to enhance the measurement range a second laser can be used to generate a synthetic wavelength. This will allow the quantification of surface variations in the micrometer range with an aimed uncertainty of less than 0.1 &mgr;m. First results on phase measurements of different samples are presented and discussed.
Optoelectronics System Design and Optoelectronic Instruments
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Control of the deformation for the millimeter wave range radiotelescope mirrors
Igor Konyakhin, Yury Artemenko, Aleksandr Timofeev
The mirror construction of the radiotelescope for millimetre wave range requires to measure the line deformation of mirror's surface. Now the control system is based on the trilateration method and it uses three laser distance-meters. This type of the measuring system can't be used for new radio-telescope RT-70 (Suffa). Following issues dealing with this problem are described in this article: 1) the possibility of the design of deformation measurement system based on triangular method 2) the new scheme of optic-electronic measurement system. The great attention during the research was paid to the experimental approval of the theoretical results. The model of the described system had the following characteristics: infrared emission diode AL107B by power 15 mWt as sources of radiation; the objective by the focal length 405 mm as aperture of receiver video-camera, the CMOS matrix receiver by type OV05610 Color CMOS QSXGA with 2592*1944 pixels and one pixel size (2.8*2.8) &mgr;m2 produced OmniVision as image analyzer . The computer simulation error and the experimental error measurement was 0.05 mm at the range 30 mm on a working distance 25 m, that allows to measure the deformation of radiotelescope construction with the mirror diameter 70 m.
Design and test of optoelectronic system of alignment control based on CCD camera
A. G. Anisimov, A. A. Gorbachyov, A. V. Krasnyashchikh, et al.
In this work, design, implementation and test of a system intended for positioning of the elements of turbine units relative to the line of shaft with high precision, are discussed. A procedure of the conversion of coordinates from the instrument system into the system connected with the practical position of the axis of turbine has been devised. It is shown that optoelectronic systems of aligment built by autoreflexive scheme can be used for high precision measurements.
CCD photoelectric measurements in calibrators for vehicle headlamp tester
Yi Lu, Zai Luo, Guiying Yu, et al.
Vehicle headlamp is a very important component for safe driving. The calibration of vehicle headlamp must be done in accordance with standard (JJG967-2001), such as the distribution of shade and the luminosity distribution of far light and close light. Photoelectric measurements, for example, electronic scanning system, dot array of photoelectric cell system and CCD measurement system, were used to research the shade distribution and the luminosity distribution. In order to expedite the measuring process and acquire more accurate parameters, CCD measurement system is proposed to measure more characteristic parameters of headlamp at higher speed. Image processing technology is utilized to get the characteristic parameters such as luminous intensity and optic axis deviation angle for headlamp. Some software algorithms of digital image processing can be used to achieve an uncertainty of luminous intensity of less than or equal to 2%, and an uncertainty of deviation angle of optic axis of less than or equal to 1.6 minute. Experimental results showed that it has many advantages such as high precision, good repetition.
Design of nano-lithographic system based on phase photon sieve
Wenbo Jiang, Song Hu
A nano-lithographic system based on phase photon sieve is proposed in this paper to overcome the disadvantages of zone plate array lithographic system and amplitude photon sieve lithographic system. As an important part of the system performance, the resolution of this system is mainly decided by the diffractive element. The phase photon sieve was used as the diffractive element in the proposed system. The structure and performance of the phase photon sieve is therefore very important to the resolution of this system. So, two methods are proposed for the designs and fabrication of the lithographic system based on phase photon sieve. The feasibility of using this system to realize nano-lithography with a resolution is of less than 100nm was then discussed. It is shown through analysis that the system not only has higher resolution and image contrast than the zone plate array lithographic system but also has higher diffractive efficiency than the amplitude photon sieve lithographic system. As a novel lithographic technique, the phase photon sieve lithographic system also offers new opportunities for high resolution X-ray microscopy and spectroscopy in physical and life sciences.
Measurement of minimum resolvable contrast based on human visual property
Yuan Zhang, Jingmin Dai, Wenjuan Li
In order to evaluate the imaging quality of a visible imaging system by measuring the minimum resolvable contrast (MRC), a novel MRC measurement method is proposed to judge the test patterns at different spatial frequencies and contrasts so that the right pattern can be identified using a computer instead of human eyes. A MRC measurement system with two integrating spheres is therefore developed. The two integrating spheres can be used to illuminate either side of the target and the contrasts of patterns on the target can be changed by controlling the special attenuators near the entrances of the two integrating spheres. During the judgment human visual properties to the luminance and frequency are considered, the computer can therefore simulate human eyes better. Experimental results indicate that the errors of measuring the luminance can be controlled within ..0.3cd/m2, which offers a guaranteed precision for the measurement of MRC. The MRC values at all the frequencies are less than those by observers. The measurement of MRC is not influenced by human subjective factors. This method can be used to measure the MRC of a visible imaging system more accurately and helps to realize the automatic measurement of MRC.
Design of a probe for two-dimensional small angle detection
Haixia He, Xuanze Wang, Yuning Zhong, et al.
A novel two-dimensional small angle probe is introduced, which is based on principle of auto-collimation and utilizes quadrant Si-photoelectric detector (QPD) as detection device. AC modulation, AC magnification and absolute value demodulation are incorporated to restrain the DC excursion caused by background light and noise etc and to improve the sensitivity and stability of angle detection. To ensure that while the laser is shining, the current signal (converted into voltage signal) of QPD also is linear to the AC modulation voltage, this paper adopted AC modulation signal (5400Hz) with a DC offset. AC magnification circuit with reasonable parameters is designed to inhibit DC drift and the impact of industrial frequency noise and to ensure good amplification to signal frequency at the same time. A piezoelectric-driven micro-angle generator is designed to demarcate the angle. The calibration data are input to single chip, and the measurement of angles can be shown in SMC1602A.
Computer modeling of the optic-electronic system for deformation measurement of radio-telescope counter-reflector
Ilya Kaliteevskiy, Igor Konyakhin
The metrological support of many measurement tasks requires measuring spatial position of some objects in respect to rigid base. The microwave radio-telescope development requires high-precision control of the position of the counterreflector. The construction elements weight and thermal deformation leads to changes of position and linear shift of each planar section in respect to ideal parabolic shape. In this case it is necessary to implement control system for measuring these deformations of the reflector. For determination of the actual shape of the reflector control objects (light-emitting diodes, LED) placed on the reflector, and their coordinates in respect to motionless construction element (base ring placed on the top main mirror) are measured by triangulation method using CCD camera, which determines vision angles of LEDs. Analysis of relations of primary errors of measurements and errors of determinations of actual coordinates of the reflectors confirm feasibility of the whole system of control of the shape of counter-reflector.
Universal opto-electronic measuring modules in distributed measuring systems
Sergey Yaryshev, Igor Konyakhin, Alexander Timofeev
Large or long objects require measuring systems as a combination of more than one measuring instrument. In this case the combination of instruments is a network system consists from several measuring modules and one central module. Measuring modules make the preliminary computation of measuring information and translate it to the central module for final computation of measuring parameters. The central module also makes statistics of measuring and archive of information. Some tasks require the noncontact methods of measuring angular and linear coordinates of objects or places. The opto-electronic measuring devices (OEMD) are ideal for these purposes. These devices also have other advantages like great precision, calibration and adaptation. In this article variants of the distributed measuring systems are described. The basic attention is given to the description of the unified opto-electronic modules for measurement of angular and linear coordinates.
Solar micro-power system for self-powered wireless sensor nodes
In self-powered wireless sensor nodes, the efficiency for environmental energy harvesting, storage and management determines the lifetime and environmental adaptability of the sensor nodes. However, the method of improving output efficiency for traditional photovoltaic power generation is not suitable for a solar micro-power system due to the special requirements for its application. This paper presents a solar micro-power system designed for a solar self-powered wireless sensor node. The Maximum Power Point Tracking (MPPT) of solar cells and energy storage are realized by the hybrid energy storage structure and "window" control. Meanwhile, the mathematical model of energy harvesting, storing and management is formulated. In the novel system, the output conversion efficiency of solar cells is 12%.
Conformal optical design using counterrotating wedges and Zernike Fringe Sag surfaces
Conformal domes are often deviated greatly from spherical surface descriptions, so severe aberrations which vary with the field-of-regard (FOR) angle are introduced by the domes. Therefore dynamic correction is required. Two counterrotating Risley prisms and two lenses are used to correct the dynamic aberrations. The inner surfaces of the counterrotating prisms and the two lenses are described by Zernike Fringe polynomials. The scan of the field of regard is achieved by counterrotating the Risley prisms about the optical axis. The performance after correction in terms of Zernike aberrations and RMS spot size versus FOR angle is reported by an example. For comparison, the RMS spot radius is reduced to 16-68 &mgr;m after the final correction, which is approximately 0.8-4.5 times Ariy spot radius, which is much better than the 30.2-69.1 times in the baseline system. The design results show that the counterrotating wedges and the two lenses which both have Zernike fringe sag inner surfaces are good correctors in conformal optical design.
Design and modal analysis of optical and mechanical structures of a space infrared camera
Guangyu Zhang, Dewei Sun, Funian Long
Space infrared cameras have been widely used for weather prediction, earth resource detection, military reconnaissance and astronomy observation. In order to design and produce an excellent space camera, the optical and mechanical structures of the camera are deeply investigated. Firstly, according to the technical targets and interface requirements for infrared sensor, optical modulation transfer function (MTF) must be up to 0.65 in the central field and more than 0.55 in the marginal field at the cut-off frequency of the optical system. Secondly, in accordance with the requirement of optical system, the structure of body tube is designed and a new type of material- graphite fiber reinforced aluminium matrix composite (Gr/Al composite) is used for the first time. The weight of Gr/Al composite body tube is 31.8% lighter than that of Titanium alloy. Thirdly, in terms of the theory of modal analysis, the resonance frequencies and modal sharps of body tube are acquired. The first order resonance frequency is 292Hz. Finally, the test of random vibration is conducted. Experimental results indicate that optical and mechanical systems do not change after vibration test. Namely, the research above suggests that space infrared camera has an important utility value in the space remote sensing field.
Synchronization of binocular motion parameters optoelectronic measurement system
Lingfei Zhang, Dong Ye, Rensheng Che, et al.
The synchronization between high-speed digital cameras and computers is very important for the binocular vision system based on light-weighted passive IR reflective markers and IR LED array PCB board, which is often used to measure the 3-D motion parameters of a rocket motor. In order to solve this problem, a comparison on the existing approaches to camera synchronization in the published literature was conducted. The advantages and disadvantages of the currently used methods were illustrated and their suitable applications were discussed. A new method, which uses self-made hardware resetting camera and software triggering image acquisition board, is provided. The self-made hardware is used to send TTL signal to two image acquisition boards one time per second. The TTL signal is used to reset two cameras and two image acquisition boards as PRIN signal, and then two image acquisition boards send same EXSYNC signal to two cameras. In this way, two cameras can be synchronized to exposure and capture images in the mean time. The test results indicated that the new approach designed in this paper can meet the demand of image acquisition at a speed of 200f/s, whose synchronization accuracy is up to micro second.
Calculations of backscattering optics characteristic of soot particles
Jian Xing, Xiaogang Sun, Xin Qian
The backscattering coefficient and intensities of soot particles were calculated using Mie scattering theory for the different incidences laser wavelengths and particle radii with complex refractive index also talked into consideration. The calculation results indicated that at a scatter angle of 180°,the backscattering intensities can go up by 30% of forward scattering intensities at different radii of particles if the resource laser wavelength is properly selected. This conclusion provides a theoretical basis for the selection of laser sources and detector aiming at enhancing Signal Noise Ratio.
Reconstruction of temperature field Ar plasma jet using CCD spectrum tomography technology
Jian Xing, Xu Qi, Xiaogang Sun
An Orthogonal area array CCD spectrum tomography experimental system has been proposed to realize real-time temperature diagnosis of Ar plasma jet. According to two-orthogonal-view reconstruction algorithm, two orthogonal intensity signals can realize the emission coefficient field construction, then using spectrum relativity intensity method, temperature field can be reconstructed. In this paper, two filters with different wavelength have been placed in front of two-view orthogonal CCD, and plasma jet image has been obtained, of which point light intensity has been gotten using digital image process technology according to the image of Ar plasma jet from CCD. Then using two-orthogonal-view reconstruction algorithm and spectrum relativity intensity method reconstructed the Ar plasma jet temperature field. The result shows that it agreed with the results from fiber scanning diagnosis system. The proposed experimental device contented the real-time diagnosis request of plasma jet. It provided stabile base for real-time diagnosis of plasma jet density field, pressure field and velocity field.
Nanotechnology and MEMS
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Dimensional nanometrology at the National Physical Laboratory
Andrew Yacoot, Richard Leach, Ben Hughes, et al.
The growth in nanotechnology has led to an increased requirement for traceable dimensional measurements of nanometre-sized objects and micrometre-sized objects with nanometre tolerances. To meet this challenge NPL has developed both purpose built instrumentation and added metrology to commercially available equipment. This paper describes the development and use of a selection of these instruments that include: atomic force microscopy, x-ray interferometry, a low force balance, a micro coordinate measuring machine and an areal surface texture measuring instrument.
Interferometry at the PTB Nanometer Comparator: design, status and development
J. Flügge, Ch. Weichert, H. Hu, et al.
To minimize the measurement uncertainty of one dimensional length measurements on line scales, linear encoders and interferometers the PTB in cooperation with the Dr. Johannes Heidenhain GmbH had built up a new length comparator. The Nanometer Comparator [1,2] has already proven its performance during the measurements of incremental encoders and line scales with an expanded measurement uncertainty of below 5 nm [3,4,5]. Due to the introduction of double and multiple exposure in advanced lithography techniques the overlay and registration metrology requirements will drastically increase so that reference metrology tools need to be developed further to be able to follow the resulting decrease of the specifications. Therefore, the PTB further develops the new 1D vacuum comparator to add a measurement possibility for straightness and to reach a measurement accuracy in the sub nanometer range [6]. One key development will be the interferometric measurement of all six degrees of freedom of the measurement slide of the comparator. A new multi axis heterodyne interferometer electronics and optical interferometer designs minimizing nonlinearities by spatially separated beams are under development.
DLC films as anti-stiction coatings for MEMS
Xin Li, Chao Zhang, Jun Liu
The stiction of microstructures is still a challenging problem in spite of innovative advances in modern micromachining technology. In this paper, diamond-like carbon films were suggested as a solution for this problem. The microwave electron cyclotron resonance plasma enhanced CVD equipment has been applied to prepare the DLC films. Confocal Raman spectra confirmed the DLC characteristics of the prepared films. Water contact angle increased from <30° on oxide-coated surfaces, to >110° on DLC-coated surfaces. The adhesion force of the DLC films was as low as 3.8nN measured by AFM, whereas the adhesion force of the oxide-coated surfaces was approximately 11.2nN. The polysilicon cantilever beam arrays have been used to determine the success of DLC coating for releasing microstructures. DLC films were prepared under the polysilicon cantilever beams with the sacrificial etching technology. The beam arrays were checked with scanning electron microscope. When the DLC films presented, the average longest detachment length was approximately 145 &mgr;m. While the DLC films didn't present, the average critical detachment length was shorter than 80..m. These results indicated the stiction of polysilicon cantilever beams was effectively restrained with DLC coatings.
Experimental study on curve-baffle characteristics of pneu-pin sensor with differential pressure
Fengwei Wang, Hui Zhang, Shanxi Deng, et al.
This paper presents the design and working principle of a pneu-pin sensor based on a gas path with differential pressure, and the study on its curve-baffle characteristics. The measurement range of the sensor is about 32 &mgr;m, with a resolution of 0.03 &mgr;m and less than an uncertainty of 0.3 &mgr;m. It is found through research on the curve-baffle characteristics with different curvature radius of steel balls that the axis of the pneumatic probe does not need to go through the geometric centre of work-piece, and so, the high accuracy positioning of the work-piece is avoided. Therefore, the pneumatic measurement technology researched in this paper can be applied to high accuracy non-contact dimension of measurement of different curvature radius of work-pieces.
Direct methanol fuel cell stack based on MEMS technology
Yufeng Zhang, Xiaochuan Tang, Zhenyu Yuan, et al.
This paper presents a design configuration of silicon-based micro direct methanol fuel cell (DMFC) stack in a planar array. The integrated series connection is oriented in a "flip-flop" configuration with electrical interconnections made by thin-film metal layers that coat the flow channels etched in the silicon substrate. The configuration features small connection space and low contact resistance. The MEMS fabrication process was utilized to fabricate the silicon plates of DMFC stack. This DMFC stack with an active area of 64mm x 11mm was characterized at room temperature and normal atmosphere. Experimental results show that the prototype stack is able to generate an open-circuit voltage of 2.7V and a maximum power density of 2.2mW/cm2, which demonstrate the feasibility of this new DMFC stack configuration.
Experimental investigation of CO2 bubbles behavior in the anode flow fields of a micro direct methanol fuel cell
Bo Zhang, Yufeng Zhang, Peng Zhang, et al.
CO2 gas bubbles have a great effect on the &mgr;DMFC (Micro Direct Methanol Fuel Cell) as the anode resultants. Visualization technique is one of the most important tools to study the formation, movement, and removal of CO2 gas bubbles. This paper presents an air-breathing micro direct methanol fuel cell made of PMMA for the visualization research. Four types of flow fields are fabricated in the anode plates. Different from the traditional &mgr;DMFCs, the stainless steel mesh is adopted as the current collector. The observation and study of CO2 bubbles behavior show that the quantities and bulks of CO2 gas bubbles increased as the current densities became higher. In addition, anode methanol solution flow rates and cell orientations also have complicated influence on the &mgr;DMFC performance.
Design and fabrication of a novel portable passive DMFC stack
We designed and fabricated a new portable passive DMFC stack with its volume significantly reduced. Its high efficiency and load regulation performance were also demonstrated through experiments, and its stability seemed to be very good. We achieved a maximum power density of 3.9mW/cm2 with a 2M methanol concentration under ambient conditions. This performance is better than that of a conventional DMFC. The volume of the 10-cell series connection DMFC stack is only 42mm x 42mm x 40mm. Due to its stable performance and easy fabrication, this structure is believed to be applicable for portable small-scale DMFC stack.
Basic research on micro-nano-instruments by femtosecond laser ablation on metal surface
Xiaochang Ni, Ru Hong, Qi Sun, et al.
Nano-particles and nano-period ripples can be used to form some micro-nano-instruments in microelectronics. In this paper a femtosecond (fs) pulse laser (148fs, 1KHz, center wavelength=775nm) is used to irradiate on metal surface, then nano-particles and nano-period ripples can be obtained in the focal scale, the size of which is shorter than the center wavelength. For describing the formation time and characteristic of nano-particles and nano-period ripples, we have increased the laser fluence from the threshold of material to a higher value and increased the laser exposure time in fixed laser fluence on different materials. Experimental results show that nano-particles occur earlier than nano-period ripples. And as the fs laser pulse number being increased, the periodical nano-ripples is clearer and clearer and the depth of ripples is deeper and deeper. Finally, permanent ablation will occur in the focal scale basing on the nano-ripples. After surface plasmon polaritons theory is used, the period of nano-ripples can be explained exactly. This work is the basic research for micro-nano-instruments by fs laser ablation technique on metal surface.
Simulation of forces on Mie micro-particles in laser trap
Xiao-na Wang, Jian Bai, Tian-tai Guo, et al.
This paper concerns the mathematical model and simulation of forces on Mie micro-particles in laser trap. To make the mathematical models suitable for particles with arbitrary shape, the surface of Mie particle is divided into many microplanes, then the radiation pressure resulting from the interaction between a single incident light and a micro-plane and a individual ray tracing is obtained using the geometrical optical theory. A computer simulation program based on this mathematical model is designed to calculate the trapping force on Mie micro-particles with arbitrary shape (sphere, cone, polyhedron and particle with smooth surface).The simulation result for the trapping forces of spherical particles is consistent with that in reference [1], and comparisons are made between spherical particles and spherical particles reconstructed from NURBS, and between conical particles and conical particles reconstructed from polyhedron. These results verify the simulation program, so it can be an effective design and analysis tool for the application of laser trapping in nanometer testing and manufacturing.
Nanometer-scale manipulator and ultrasonic cutter using an atomic force microscope controlled by a haptic device
F. Iwata, S. Kawanishi, A. Sasaki, et al.
We describe a nanometer-scale manipulatoion and cutting method using ultrasonic oscillation scratching. The system is based on a modified atomic force microscope (AFM) coupled with a haptic device as a human interface. By handling the haptic device, the operator can directly move the AFM probe to manipulate nanometer scale objects and cut a surface while feeling the reaction from the surface in his or her fingers. As for manipulation using the system, nanometer-scale spheres were controllably moved by feeling the sensation of the AFM probe touching the spheres. As for cutting performance, the samples were prepared on an AT-cut quartz crystal resonator (QCR) set on an AFM sample holder. The QCR oscillates at its resonance frequency (9 MHz) with an amplitude of a few nanometers. Thus it is possible to cut the sample surface smoothly by the interaction between the AFM probe and the oscillating surface, even when the samples are viscoelastics such as polymers and biological samples. The ultrasonic nano-manipulation and cutting system would be a very useful and effective tool in the fields of nanometer-scale engineering and biological sciences.
Experimental study of nanometrological AFM based on 3-D F-P interferometers
Nanometrological AFM with high-resolution interferometers can be used for a wide-ranged measurements and be traceable to the unit of length, but such problems as reduction of measuring uncertainty, correction of complex nonlinearity error and advancing of repeatability restrict the application of MAFM. This paper presents the design of metrological AFM based on double F-P interferometer in XYZ directions, which consists of one He-Ne laser, one '1 x 3' fiber splitter and four self-focused lens instead of three sets of He-Ne laser. This design can not only avoid the traceable error caused by different optical sources in three directions, but also improve the resolution of the measurement through the transfer of nano-dimension to a pair of fundamental frequency pulse interval, while external noise and disturbance caused by outside environment are dramatically eliminated using double F-P interferometers of the same cavity length and material. Nano-dimensional measurement and stability test have been successfully accomplished with double F-P system in X or Z direction with measurement sensitivity of &lgr;/2000nm , which meets the requirement of nanometrology.
Portable UV absorbance detection system for microchip electrophoresis
Li Tian, Wei J. Wang, Xiaowei Liu, et al.
This paper presents a new structure of MCE chip on PMMA substrate prepared to improve the original chip structure with UV absorbance detection mode. The chip microchannels are fabricated by CNC milling and packaged with hot embossing process at the processing condition of 80°C, 5min, 0MPa with a manual powder pressing machine. All the micro-channels is 150&mgr;m * 150&mgr;m. Mobility &mgr;eo of PMMA MCE chip is 2 9.15e-004cm Vs in the solution of 10mmol/L Na2CrO4 and 0.5mmol/L CTAB. Adopting indirect UV photometric detection mode, the inorganic anion Cl- capillary electrophoresis is carried out with an in-house UV detection system. The BGE buffer is 10 mmol/L Na2CrO4 and 0.5mmol/L CTAB, and the electrophoresis voltage is 616V. Test widow is 0.3*2 mm2. Test results indicate that both in-house UV detection system and MCE chip of PMMA substrate have the basic function and could be applied in the chemical analysis field.
Compensation of motion error in a high accuracy AFM
Yuguo Cui, Yoshikazu Arai, Gaofa He, et al.
An atomic force microscope (AFM) system is used for large-area measurement with a spiral scanning strategy, which is composed of an air slide, an air spindle and a probe unit. The motion error which is brought from the air slide and the air spindle will increase with the increasing of the measurement area. Then the measurement accuracy will decrease. In order to achieve a high speed and high accuracy measurement, the probe scans along X-direction with constant height mode driven by the air slide, and at the same time, based on the change way of the motion error, it moves along Zdirection conducted by piezoactuator. According to the above method of error compensation, the profile measurement experiment of a micro-structured surface has been carried out. The experimental result shows that this method is effective for eliminating motion error, and it can achieve high speed and precision measurement of micro-structured surface.
An atomic force microscopy study on fouling characteristics of modified PES membrane in submerged membrane bioreactor for domestic wastewater treatment
Shuo Liu, Hongjun Han, Yanping Liu, et al.
To investigate the fouling characteristics of modified PES membrane in submerged Membrane Bioreactor (MBR) for domestic wastewater treatment, Atomic Force Microscope (AFM) study was conducted to analyze the microstructure characteristics of PES membrane. Surface roughness and section analysis of both virgin and fouled membrane were achieved by software of NanoScope 6.12. Compared to the virgin membrane, the average roughness (Ra), square average roughness (Rms) and ten points average roughness (Rz) of fouled membrane were increased by 100.6nm, 133.7nm and 330.7nm respectively. The section analysis results indicated that the cake layer formed and membrane pore blocked were the main causes for the increase of TMP. Micro-filtration resistance analysis was conducted to support the results of AFM analysis. It is showed that membrane resistance, cake resistance, pore blocking and irreversible fouling resistance is 0.755, 1.721 and 1.386 respectively, which contributed 20%, 44%, and 36%, respectively, to total resistance of submerged MBR (at MLSS 6000mg/L and flux 21.9L/m2·h). The results proved that AFM could be used to properly describe the fouling characteristics of modified PES membrane in submerged MBR through roughness and section analysis.
A diffraction grating scale for long range and nanometer resolution
Kuang-Chao Fan, Bai-Kun Li, Chi-Hui Liu
This paper presents a novel design of a laser linear encoder based on the principle of diffractive interferometry. It adopts a special design in optical path that can increase the alignment tolerance between the optical head and the grating. Because of the simple optical configuration and the merit of compact size, it can effectively reduce the environmental disturbance and allow higher stability. In addition, the signal process circuit can effectively decrease three major errors: the DC shift difference, the electronic gain difference and the phase orthogonal error of two sinusoid al output signals. The resolution can reach to 1nm. Experiment results showed the standard deviation was below 17nm for 15mm travel in normal laboratory environment.
A new fiber Bragg grating based accelerometer
Yongjie Wang, Rui Wang, Fang Li, et al.
A new fiber Bragg grating (FBG) based accelerometer is developed for monitoring seismic activities induced by moving vehicles. A theoretical model of the sensor is established, and analytical formulas of describing the sensitivity and resonant frequency are provided. Sensors of this type are fabricated and tested. The experimental results show that they have a sensitivity of 162.8 pm/G and a resonant frequency of 242.9Hz. The minimum detectable signal of the whole sensing system is about 12.1 &mgr;g. A field test is carried out to find out that for tracked vehicles' monitoring, a single sensor has a detection range of about 300 meters, indicating a promising future in practical use.
A multi-function tribological probe microscope with a hot tip for thermal measurement
Z. Yue, X. Liu, Z. Cai, et al.
Surface mechanical and thermal properties objectively affect our touch-feel perception. However, it is still far from known that how the surface properties affect the stimulus to our nerve system and make us feel warm or cold, hard or soft, rough or smooth, etc. Physically, although the surface properties can be measured individually by different instruments, it is desirable to have a multifunctional instrument to facilitate the investigation of the relationship between the surface physical characteristics and the corresponding perceived touch feeling by human. In our previous work, a novel multi-functional tribological probe microscope (TPM) was developed to provide mappings of four functions of a surface at micro and nanometer scales. The four functions of surface topography, hardness, Young's modulus and friction are measured in a single scan set-up and they are potentially linked in space and time to provide cross-correlation in between. In this paper, to achieve the additional function of micro thermal analysis, we proposed a new scheme of thermal probe with a hot wire (Wollaston wire) buried beneath a Berkovich diamond indenter. The details of mechanical design and associated electronic circuits are presented. Meanwhile, the paper also explains the principle of the hot-tip technique by relating its signals to established physical parameters of materials, a method that separates sample information from the artifact caused by the indentation geometry of the diamond tip. Experimental results of thermal conductivity measurements on certain metal specimens are discussed.
Estimation of magnetic nano-particles' size distribution using their magnetization curve
Ming Zhou, Wenzhong Liu, Li Kong
In this paper, we illustrate a method of reconstructing the size distribution of magnetic nano-particles (MNP) using a magnetization curve that was measured on a water-based MNP. The objective was to find solutions to the ill-posed problem in the matrix equation Ax=b, which was obtained from the numerical model on magnetization. Prior the use of Singular Value Decomposition (SVD), a method utilizing a total of 60 sample points of magnetization curves was obtained from Superconducting QUantum Interface Devices (SQUID) in attempts to achieve a favorable solution. However, eliminating oscillation in this manner was proven difficult. Therefore, the Tikhonov regulation (ATA-&agr;I) was offered in the solution to overcome the above-mentioned ill-posed problem. Size distributions from Tikhonov SVD (TSVD) were found stable. As predicted in previous theoretical analyses, a lognormal-like distribution of the MNP could be observed in single-origin MNP EMG1111.
Simulation of filling characteristics during hot embossing of polymer microstructures
Peng Jin, Yulong Gao, Tingting Liu
Hot embossing is an effective way to achieve high-quality Microstructures at low cost. At present papers, the effects of geometry and shear on filling profile and polymer deformation have studied through experiments or computations. In this paper, the parameters on different polymer deformation modes: single peak, dual peak and embossing stage have researched. Especially it is referred that the mainly reasons of embossing stage phenomenon are the ratio of cavity width to height 2w/hi, the ratio of cavity width to tool width w/(w+s), and shear thinning. In addition, the temperature variation of polymer due to internal friction has discussed with evolution of imprint speed. And the simulation results prove a better coincidence with experiments.
Development of high-temperature piezoresistive pressure sensor based silicon on insulator
Shixin Pang, Xin Li, Qin Liu, et al.
Silicon on insulator (SOI) substrate was prepared using ion implantation of oxygen technique. For piezoresistive detection, the top layer (0.2 &mgr;m thick) silicon was used as an active material with the excellent single crystal silicon properties. The structure of the pressure sensor chip was simulated and analyzed using the finite element method. The pressure gauge chips were manufactured using MEMS techniques. The Si3N4 films were applied for the mask, and the silicon cups were manufactured using KOH anisotropic wet etching process. Cr/Ni/Au multi-layers metal electrodes were applied to guarantee the reliable work at high temperature. The manufactured sensors were measured with an applied pressure of 0 to 6.0MPa at 300 . The test results showed that the sensitivity was approximately 30mV/ (mA MPa), the non-linearity was less than 1.5&perthou; FS, the repetition was less than 0.9&perthou; FS. The research showed that the SOI piezoresistive pressure sensor could reliably work at a high temperature.