Data processing of vertical scanning white-light interferometry based on particle swarm optimization
Author(s):
Jie Hu;
Changcai Cui;
Hui Huang;
Ruifang Ye
Show Abstract
In order to precisely locate the position of zero optical path difference (ZOPD) between the measuring light beam and the reference light beam in Vertical Scanning White-light Interferometer and then realize accurate surface measurement, the Particle Swarm Optimization (PSO) was used to process the interferometry data captured by a CCD camera. The envelope line of series of intensities of every pixel was supposed to be approximated by a Gaussian curve first. Then its parameters were optimized to find the best Gaussian curve as well as the position of ZOPD by the PSO with an objective function which minimized the residual sum of squares between the measured data and theoretical fitting curve. Finally, the measured surface can be reconstructed according to a series of best positions of ZOPD obtained by the proposed method. The simulation data and sampled data of two standard samples with different kinds of reticles from repetitive test show that the PSO is suitable for precisely locating the ZOPD with low requirements of step sampling and a small amount of pictures. Therefore, without reducing the precision, the PSO can be used in data processing of the white-light interferometry system with relatively low requirements for stepping hardware.
Technology of time-interval measurement in Time and Frequency Remote Calibration System
Author(s):
Tao He;
Huijun Zhang;
Zhixiong Zhao;
Xiaohui Li
Show Abstract
Time and Frequency Remote Calibration System (TFRCS) based on GPS common-view has been designed by National Time Service Center (NTSC), which is used to realize time and frequency calibration for remote users as well as the precise time traceable to UTC (NTSC) for the local reference time. The high precision PCI plug-in time interval counter is the critical measuring instrument of TFRCS, which is self developed to measure the time interval between two 1 PPS signals from GPS timing receiver and local reference time. The basic principle of time interval counter and the realization method of bottom driver based on PCI are reviewed. On this basis, the method and the measuring results of time interval data based on the driver program are then presented. An experiment has been designed to test the performance of the self developed time interval counter. Research on the technology of time-interval measurement has a very important significance for TFRCS. Furthermore, it also can be used in the field of high precision time-interval measurement.
Pneumatic hammer in aerostatic thrust bearings with single orifice compensation
Author(s):
Zhongke Kong;
Jizhong Tao
Show Abstract
In dealing with the phenomenon of the pneumatic hammer in aerostatic thrust bearings, the vibrant model of the one-single freedom system has been established to study the pneumatic hammer from the point of sympathetic vibration. It is found that the bearings show a tendency to result in the pneumatic hammer with the increase of air supply pressure, and the occurrence probability of the pneumatic hammer will be reduced when the gas film thickness is maintained within a certain range. Meanwhile, the existence of the pneumatic hammer, which is caused by sympathetic vibration, is experimentally verified, and it is found that gas bearings undergo certain disturbance, which causes the system to produce micro breadth vibration. Accordingly, the micro breadth vibration causes the gas film and thrust face to form flow/structure coupled to excite the pneumatic hammer. Therefore, it provides another path to study the pneumatic hammer and is of academic value.
Extracting crack signal of magnetic ring based on MAX262
Author(s):
Hao Xu;
De-xing Hou;
Jian Qiu;
Shu-liang Ye
Show Abstract
Magnetic rings are widely used in electronic manufacturing. In the production process, various types of cracks exist, which severely reduce product performance. So it has important practical significance for the efficiency and accuracy detection of the magnetic rings defects. In this paper, a detecting instrument for magnetic rings defects is designed based on magnetostrictive effect, which uses an alternating magnetic field to encourage the ring producing vibration at one end of the ring, and at the other end a vibration transducer is used to catch the vibration signal. Considering that signals of vibration are difficult to obtain, a programmable filter based on the MAX262 chip is designed, using fourth-order Chebyshev band-pass filtering method to extract the weak signal ,which is used to determine the ring cracks. Numerous ring experiments show that this method can effectively detect the ring crack.
Redundant manipulator based autonomous scanning for unknown variable cross-section pipe
Author(s):
Guolei Wang;
Jiubin Tan;
Chuanqing Zhang;
Huabin Yin
Show Abstract
A laser scanning device installed at the end of the redundant manipulator is designed, in order to solve the problem of autonomous scanning and model reconstruction for unknown variable cross-section pipe. Firstly, the chosen laser range sensor and the scanner head structure which can rotate 360 degrees are described. Secondly, measurement model is built and a cross-section intersection based forward scanning method (CIFSM) for unknown variable cross-section pipe with our laser scanning device is put forward. Thirdly, a hypothetical boundary based obstacle avoidance scanning path planning algorithm (HBSPPA) is proposed. In scanning experiments, two representative cross-section shapes can both be scanned autonomously and rebuilt accurately in coordinate system of redundant manipulator. The results demonstrate that the proposed device and method are effective and practical.
Contact aiming system of 2m laser automatic interferometric comparator
Author(s):
Shuanghua Sun;
Xiaoyou Ye;
Lingding Zou;
Hongtang Gao;
Xiaochuan Gan;
Xueping Shen
Show Abstract
Composition and principle of 2m laser automatic interferometric comparator were introduced. A novel contact aiming system based on high precision inductance sensor was designed. The zero-cross trigger signal of inductance sensor output voltage was treated as the aiming signal. A rotating mechanism was designed and a segmental shifting motion control model was established. Two key problems, avoiding probe crash and aiming repeatability, were solved. The one dimension end standards such as gauge block, step gauge could be measured directly by this means. The data of test revealed that aiming repeatability was less than 0.2μm.
An evaluation method of a micro-arrayed multispectral filter mosaic
Author(s):
Jianhuan Zhang;
Shan Lin;
Chentao Zhang;
Yanping Chen;
Linghua Kong;
Fengxin Chen
Show Abstract
In recent decades, multispectral imaging (MSI) has been approved as an effective tool to detect and discriminate targets in industrial application. A narrowband micro-arrayed multispectral filter mosaic (MSFM) based on MSI technology is proposed to miniaturize MSI instrumentation. There are many reasons to believe that this innovation is going to replace the traditional methods of filtering or dispersing light and bring MSI applications to more industrial fields. However, highly integrated micro pieces of MSFM are arranged periodically, and the spectral profiles of two adjacent pieces cause a spectral interference (SI). To express and estimate the extent of SI, an evaluation method is proposed and its feasibility is reported in this paper. Additionally, the ways reducing the extent of SI are suggested.
Low frequency time-code time service method based on frequency sharing
Author(s):
Ping Feng;
Zhiyong Zhang;
Guichen Wu;
Yan Bai;
Xiaofeng Ding
Show Abstract
Low frequency time-code timing service is an important mode in the modern timing system. Low frequency time-code timing radio station (BPC) is built by National Time Service Center in China. Based on the modern signal characteristic of BPC, a new timing method based on frequency sharing is presented, which is the additional spread spectrum modulation timing method in idle carrier wave of BPC. The rationale of the additional spread spectrum modulation timing method in BPC is researched. The performance of the method is analyzed. The research results indicate that the coverage of low frequency signal can be enlarged by the additional spread spectrum modulation timing method, and the timing precision of BPC will be enhanced. So low frequency time-code timing service can be used broadly.
Error analysis of homodyne multi-pass interferometer with Jones matrix
Author(s):
Wei Li;
Sitian Gao;
Mingzhen Lu;
Yushu Shi
Show Abstract
Interferometer is widely used in precise displacement measurement. Nonlinearity of interferometer is one of the major limits when using interferometers in nanometer displacement measurement. Nonlinearity is caused by phase mixing in homodyne interferometers due to the imperfect of polarization optical components. Both the detection part and interferometer part cause nonlinearity. In this study, the polarization mixing effect of multi-pass interferometer caused by the interferometer part is analyzed by Jones matrix. The effects of polarization beam splitter and wave plate on the nonlinearity are studied. The results show that the polarization mixing effect in multi-pass interferometers cause different orders of frequency components. The nonlinearity error is asymmetry with different harmonic components compared to that caused by the detection part.
Analysis and simulation of multipath error for satellite navigation signals
Author(s):
Yan Bai;
Xiao-chun Lu;
Hao Hong
Show Abstract
Multipath error is an important error source in the tracking measurement of the navigation signals, and the multipath analysis is also significant to the signal system designing and signal optimizing. The multipath error envelope curve and average multipath error based on non-coherent EMLP (Early Minus Late Power) are usually used to measure the multipath rejection ability of the navigation signals. Now, the signal parameters of COMPASS satellite navigation system have been published. The method and principle to analyzing multipath error are given in this paper, the multipath performance of different signals adopted by COMPASS system is analyzed, and the simulation results are given. The analysis results in this paper can offer the research basic and reference to the system designing of the satellite navigation in our country.
A method to identify material based on spectrum analyses
Author(s):
L. Zhang;
J. M. Dai;
Y. F. Zhang;
W. D. Pan;
Z. Yin
Show Abstract
According to radiation temperature measurement theory, the key of temperature measurement is to choose the appropriate temperature model, which depends on the type of measured material. So how to identify the material type is significant to measure its surface temperature. Different materials have different spectral characters at the same temperature. In this paper, a method based on spectrum analysis is proposed to identify material. The spectrum of four kinds of materials is measured using Fourier transform infrared spectrometer (FTIR) at the same temperature 873K. The peak values extracted from each spectrum are used to train the identification algorithm. Then one material is chosen from the measured materials to verify the identification algorithm if the type of material can be identified. The experimental results suggest that the new method based on spectrum analyses can accurately identify the type of material.
A method to auto-estimate edge detection direction
Author(s):
Z. Yin;
B. G. Liu;
F. D. Chen;
G. D. Liu;
F. Wan
Show Abstract
In machine vision measurement, the edge is a key point for fitting geometric parameter. There are two problems in the edge detection process. First, there is redundant information for the object with complex shape in the field of the view. Second, the surface of the object is full of texture which is misidentified as the edge. The texture processes similar feature to the edge and cannot be removed by filter. To solve the above problems, vision sight is proposed to get an interesting region and remove redundant information. A new algorithm based on fuzzy entropy is used to auto-estimate the edge detection direction from the pure region to mixed region in order to avoid the textures which misidentified as the edge. Comparing the algorithm with Canny, the former gets less texture points than the latter. A mask film is used as a standard to weight the validity of the algorithm. The experimental result shows that the algorithm proposed by this paper is robust and accuracy in detecting edge.
Use of polynomial approximation for reconstruction of periodic nonuniformly sampled signals
Author(s):
Wang Liu;
Jinsong Liu;
Liyan Qiao
Show Abstract
In the theoretical study and practical application of the instruments, the problem of nonuniform sampling signal reconstruction is an important research issue that is often confronted with. The use of polynomial approximation for reconstruction of traditional nonuniformly sampled signal is limited due to its huge computational cost. However, if the nonuniformly sampled signal to be processed has a periodicity, the processing speed can increase substantially. Hence, in this paper, polynomial approximation is introduced to reconstruct periodic nonuniformly sampled signal. Taking the advantage of periodic nonuniformly sampling’s recurrence, the polynomial approximation algorithm is simplified to reduce the algorithm’s computational cost significantly without sacrificing reconstruction precision. The simulation experiment for reconstructing periodic nonuniformly sampled signals is introduced to verify the feasibility and effectiveness of the simplified algorithm. The results show that the periodic nonuniform sampling signal is well reconstructed.
Dispersion compensation for absolute distance measurement based on the femtosecond optical frequency comb
Author(s):
Tengfei Wu;
Zhiguo Liang;
Peng Ye
Show Abstract
The effect of air dispersion on the femtosecond pulsed width is studied in this paper. We present the pulsed width variation with central wavelength, grating period and distance, respectively. Then the air dispersion compensation scheme based on the high-density transmissive grating is put forward to compress the pulsed width of femtosecond laser. The diffracted efficiencies variation with the groove depth and the grating period under the condition of TE and TM polarization state are also given through simulation. The scheme has advantages of compact volume and convenient operation.
Study on measuring the pose of the moving object based on binocular vision
Author(s):
Zengyu Sun;
Yajun Liang;
Jincheng Song;
Lei Guo
Show Abstract
To the question of measuring the moving object pose, a high speed and high synchronization precision spatial pose measurement system based on optical measurement was designed. The system is more convenient and more accurate. In order to realize the measurement method, a Synchronous controller was used to keep the moving object and the pose measurement system based on binocular vision model synchronized. The system can record the course with high synchronization precision. Geometry constraint relation of the special markets and optimization algorithm based on coordinates of multi-points were used in the pose algorithm of the moving object. Experimental results and theoretical analysis prove that the pose measurement method is correct and reliable. The frequency of the pose measurement system is 100 frames per second. The error of the pose angle is less than 0.05°. The pose measurement system satisfies the requirements of pose measuring in ground simulation test.
A feasibility study on the improvement of CT image with the back propagation neural network
Author(s):
Shih-Chieh Lin;
Tse-Li Wang
Show Abstract
It had been a major concern about multi-slice X-ray CT for its high radiation dose delivered to a patient. In order to reduce the radiation dose, one can either limit the dose per projection, or reduce the number of projections, or both. However, it was shown that artifact will appear when limited projections were used. In this study, the feasibility of using back propagation type artificial neural network to improve the image reconstructed using the filtered back projection is studied. Two networks were trained to reconstructed image by input information calculated using the filtered back projection method from 32, and 64 projections respectively. A series tests are also conducted to evaluate the performance of the trained networks. The results show that if information of 32 or 64 projections was used, the reconstructed images are generally improved by the use of the trained network.
Dynamic measurement technology in object separate experiment
Author(s):
Jin Cheng Song;
Yajun Liang;
Lei Guo;
Zengyu Sun
Show Abstract
In this paper, a novel experimental method is proposed in order to verify the availability and reliability in separate system. To measure the position-change caused by the fault-mode machine-separate of the electric isolator plug and to know the real switch process of the important component, the ground separate experiment is required to simulate the real object separate process and to obtain the relative position of isolate component under different separate parameter. In the experiment, a position measurement system based on high speed photograph principle is introduced which has hardware, software and gauging method of photograph measure system. A in-situ measurement system is set up by two high speed camera in order to synchronized image collection of separate process. After extracting, matching, coordinate and position calculating to the image, a relative position of the isolator component at the time of separate process can be deduced. The relative separate speed at this time can be calculated by the position parameter. The measurement system can be tested by the three-axis standard revolving stage. The results of the measurement experiment show that camera response frequency is 1000Hz, the relative error of position measurement is less than 5%, the relative error of speed measurement is less than 5% which can meet demands of experiment.
Method of projectile spinning rate processing based on acceleration compensation
Author(s):
Ruoyu Zhang;
Yuanqin Wang;
Jing Sun
Show Abstract
Slotting at the base of spin-stabilized projectile is widely used in spinning rate measurement. Confined by the structure of the base, it only suits few models of projectile. For the projectiles with special structures, such as apertures or holes at the base, the information of spinning rate in radar echo is considerably so weak that the conventional signal processing methods become invalid. Herein, a method based on acceleration compensation is proposed to extract the spinning rate from the echo of low signal to noise rate (SNR). First, an algorithm called Two Segments based FFT is adopted to estimate the coarse rate of linear frequency modulation (LFM). Next, using the coarse rate as the initial value of optimization, Golden Section method is used to search the fine rate of LFM to improve the accuracy of estimation. Then, the fine value is used to construct the reference LFM signal and compensate the effect of acceleration. At last, based on Chirp Z Transform, the method of spectrum zooming is employed to alleviate the spectrum leakage and improve the performance of spinning rate processing. Simulation shows that the precision of the spinning rate measurement is better than 0.25% for majority of the modulation indices when the SNR equals
to 0 dB.
Cloud-based evolutionary algorithm for Network on Chip (NoC) test scheduling using NoC as TAMs
Author(s):
Chuanpei Xu;
Malgorzata Chrzanowska-Jeske;
Pu Zhang;
Cong Hu
Show Abstract
Network on Chip is a novel system-on-chip paradigm. Developing an efficient test strategy is essential for future NoC development. We propose to use cloud theory to solve core test scheduling problem for NoC using NoC communication network as test access mechanisms (TAMs). A cloud model is build and used by our evolutionary algorithm to optimize NoC testing time under power consumption constraint. The goal is to use cloud evolutionary algorithm to schedule testing of NoC cores as much in parallel as possible. Experiments show that the proposed algorithm converges much faster than the tradition evolutionary algorithm and can find testing schedules that reduce NoC testing time.
A comparison of cylindricity and parallelism measurement procedures between HIT UOI and PTB
Author(s):
Otto Jusko;
Jingzhi Huang;
Wei Gu;
Helge Reimann
Show Abstract
PTB and the HIT Institute UOI (Center of Ultra-precision Optoelectronic Instrument) have developed special error
separation procedures for improving the measurement uncertainty of cylinder calibrations. Three glass cylinders, which
were custom-made by HIT, were selected to compare the performance and characteristics of the measurement
procedures. Both procedures effectively eliminate guidance errors of the measurement machines and lead to sufficiently
low measurement uncertainties.
Analysis of the elastic mechanism for contact scanning probe
Author(s):
Rui-Jun Li;
Sheng Tao;
Kuang-Chao Fan
Show Abstract
High precision contact scanning probes for measuring miniature components on micro- and nano-coordinate measuring
machines require elastic mechanisms. In order to realize the probe’s mechanical behavior and stiffness when designing
an elastic mechanism for a contact scanning probe, the elastic mechanism is analyzed by the theory of elasticity and
finite element analysis in this paper. The contact scanning probe is composed of a fiber stylus with a ball tip, a
mechanism of floating plate suspended by four leaf springs, and two optical sensors. The leaf springs experience elastic
deformation when a contact force is applied. Uniform stiffness model is analyzed. Simulation and experimental results
verify the correctness of the analysis.
Robustness of thermal error compensation model of CNC machine tool
Author(s):
Xianli Lang;
Enming Miao;
Yayun Gong;
Pengcheng Niu;
Zhishang Xu
Show Abstract
Thermal error is the major factor in restricting the accuracy of CNC machining. The modeling accuracy is the key of thermal error compensation which can achieve precision machining of CNC machine tool. The traditional thermal error compensation models mostly focus on the fitting accuracy without considering the robustness of the models, it makes the research results into practice is difficult. In this paper, the experiment of model robustness is done in different spinde speeds of leaderway V-450 machine tool. Combining fuzzy clustering and grey relevance selects temperature-sensitive points of thermal error. Using multiple linear regression model (MLR) and distributed lag model (DL) establishes model of the multi-batch experimental data and then gives robustness analysis, demonstrates the difference between fitting precision and prediction precision in engineering application, and provides a reference method to choose thermal error compensation model of CNC machine tool in the practical engineering application.
Mechanism analysis of instantaneous angular-rate measurement of gyro-test turntable with inertial devices
Author(s):
Yafei Yang;
Xiang Zhang;
Jianguo Li
Show Abstract
Gyro is a key component of inertial navigation systems. How to increase gyro’s test and calibration accuracy remains a scientific problem which requires immediate solution in the field of inertial technology for all countries around the world. To improve the accuracy of gyro-test turntable is a most efficient way for increasing gyro’s test and calibration accuracy currently. Unlike the existing domestic methods, a new method is proposed in this paper that inertial devices (high-precision gyros and accelerometers) can be used for measuring instantaneous angular rate of gyro-test turntable directly, and high accuracy and stability of the rate of gyro-test turntable can be realized through rate feedback control in order to increase the accuracy of the turntable, thus realizing the goal of increasing gyro’s test and calibration accuracy furthermore. This paper analyzes mechanism of measuring instantaneous angular rate of gyro-test turntable by using this method, and discusses feasibility of this method, and points out a research direction for increasing the accuracy of gyro-test turntable.
Two improved methods for determining complex permittivity in coaxial line of powder materials
Author(s):
Haihui Zha;
Ling Tong;
Yu Tian;
Bo Gao
Show Abstract
In this paper, two improved methods are proposed for determining the complex permittivity of the powder materials from 1 to 18 GHz. Unlike the measurements of solid materials in a two-port coaxial line, two Teflon annular spacers are used to house the powder materials. One method is to obtain the scattering parameters at the reference plane of the powder materials using an improved TRL calibration method, then reconstruct the complex permittivity based on the traditional transmission-line method. The other method is based on the measurements of the scattering parameters of two different length coaxial lines, which only loaded with two Teflon annular spacers or partially loaded with powder materials housed by two Teflon annular spacers. Those two methods are particularly suitable for a small amount of powder materials. Finally the results of the measurements of two powder materials: loess and thin sand are shown, compared with the results measured by Agilent’s 85070E dielectric probe kit.
Three-dimensional measurement and characterization of grinding tool topography
Author(s):
Changcai Cui;
Liam Blunt;
Xiangqian Jiang;
Xipeng Xu;
Hui Huang;
Ruifang Ye
Show Abstract
A comprehensive 3-dimensional measurement and characterization method for grinding tool topography was developed. A stylus instrument (SOMICRONIC, France) was used to measure the surface of a metal-bonded diamond grinding tool. The sampled data was input the software SurfStand developed by Centre for Precision Technology (CPT) for reconstruction and further characterization of the surface. Roughness parameters pertaining to the general surface and specific feature parameters relating to the grinding grits, such as height and angle peak curvature have been calculated. The methodology of measurement has been compared with that using an optical microscope. The comparison shows that the three-dimensional characterization has distinct advantages for grinding tool topography assessment. It is precise, convenient and comprehensive so it is suitable for precision measurement and analysis where an understanding of the grinding tool and its cutting ability are required.
Wheel rim stress detecting using ultrasonic testing technology
Author(s):
Jianqiang Guo;
Pei Wang;
Xiaorong Gao;
Zeyong Wang;
Quanke Zhao
Show Abstract
Train wheels should undergo heat treatment, thus producing circumferential compressive force on the tread to void crack propagation, and this way eventually increases the train wheel service life, excluding situations like wheel burst due to crack. Hem shoes braking will lead to calorification and cooling of wheel rim,in this case stress state of wheel rim will would change under the influence of caloric and mechanical load, and compressive stress will turn to circumferential tensile force. For wheels in service, small flaws appear in the shallow layer of wheel tread, and will expand into depth. Consequently, detecting of wheel rim stress state should be attached more importance. Ultrasonic testing technology is an extremely important method for convenient, fast and non-destructive detecting in routine application of wheel sets. Verification of ultrasonic detecting method in detecting stress of wheel rim is given in this paper. On experimentation platform established with wheel rim stress detecting equipment and tensile stress mechanism, ultrasonic wheel rim stress detecting method is verified to be reliable and stable in the light of contrast between theoretical and experimental results. Basing on wheel rim stress measurement method using transverse straight probe, results are obtained by measuring test block and wheel rim stress, and ultrasonic wheel rim stress detecting method is approved to be feasible in application.
High precision position control of voice coil motor based on single neuron PID
Author(s):
Liyi Li;
Qiming Chen;
Guangjun Tan;
He Zhu
Show Abstract
Voice coil motor(VCM) is widely used in high-speed and high-precision positioning control system in recent years. However, there are system uncertainty, nonlinear, modeling error, and external disturbances in the high-precision positioning control system, traditional PID control method is difficult to achieve precise positioning control. In this paper, a new position control strategy with a single neuron controller which has the capability of self-studying and self-adapting composed with PID controller is put forward, and the feedforward compensator is added to improve the dynamic response of the system in the position loop. Moreover, the disturbance observer is designed to suppress model parameter uncertainty and external disturbance signal in the current loop. In addition, the problem of high precision position control of VCM under the influence of significant disturbances is addressed, which including the gas-lubricated damping, the spring, the back EMF and ripple forces, on the basis, the mathematical model of VCM is established accurately. The simulation results show that this kind of controller can improve the dynamic characteristic and strengthen the robustness of the system, and the current loop with disturbance observer can also restrain disturbance and high frequency.
CMM probe compensation methods for measuring complex screw surface
Author(s):
Qiancheng Zhao;
Tianlong Yang;
Xiyun Yin
Show Abstract
At present, probe compensation is the key problem in measuring geometric parameters of complex screw surface with CMM due to its complicated 3D shape, aiming at this problem, some new measurement methods are proposed based on geometric feature models, expressing the screw surface and its offset surface separately. Supposing the parameter lead of a screw surface is known, it’s realized by scanning one single profile to complete probe compensation and calculate out all parameters, and the probe compensation is done by two improved methods, named as modified cross product and offset surface virtual measurement respectively, the theory and detailed process of which are discussed in this paper. After performing systematic experiments of profile scan, probe compensation and error evaluation, results show that the new measurement methods provide higher precision, stability and realizability.
Sub-pixel location with phase transfer function for star tracker
Author(s):
Jiangbo Xi;
Zongxi Song;
Wei Gao
Show Abstract
Star tracker has been widely used as a precise and reliable device for the attitude measuring of a spacecraft. The accuracy of star location will affect the accuracy of star identification and finally the accuracy of attitude measurement. This paper proposed a novel method to locate the star position with the phase transfer function (PTF). The numerical expressions are deduced with the diffraction model of the star point in 1-D and given directly in 2-D. Then calculation is performed and the accuracy is better than 2.1% pixels (SNR=20) with a 3×3 window of airy disk, which is higher than the traditional centroid method. Different sizes of the airy disk from 3 to 6 are simulated with PTF method and we find that the optimal window size is 3 to 5. Finally the Additive Gaussian Noise with SNR from 2 to 40 is introduced to evaluate the novel method and compare it with the traditional centroid method. The accuracy of the new method can reach better than 2.5% pixels and it is much robust than the traditional centroid method, which proves that the method we proposed has a good performance under the noise environment.
The development of micro-vibration for satellite
Author(s):
Shangchun Fan;
Le Cao
Show Abstract
The micro-vibration of satellite is a key factor which affects the major performance of high precision camera. At the same time, it limits the improvement of the camera resolution, and it impacts the efficiency in resource exploration and emergency treatment of serious natural disasters. This paper starts with the vibrating environment of the satellite, then analyzes the impact on the camera platform that brought by space environment. On the above basis, this paper introduces several researches and developments concerning micro-vibration measurement, satellite simulation system and on-ground test method, evaluates performance and retaliating method of measurement system which referring to the examples at home and abroad that are related to stable platform. Finally, based on national research achievement, this paper points out the developing direction about relevant technology.
New principle of processing optical aspherical components with locus compensation method
Author(s):
Heyan Wang;
Zi Xue;
Chenghao Piao;
Guoliang Yang
Show Abstract
A new principle of processing asphere with locus compensation method has been presented. The mathematical model for principle of machining aspherical surface with locus compensation method was created based on the equidistant line formula. The feasibility and practicability was analyzed and the corresponding processing program was made by MATLAB and Visual basic. The overall structure of corresponding machine tools was designed. The program can figure out the compensation error of quadratic curves and the designed machine tools can perform the functions of interception and compensation of quadratic curves , which meets the basic motion requirements of ultra-precision machining. All quadric and high order aspherical surface will be achieved and the surface form accuracy also will be improved. The structure of machine tools is simple and processing range is wide which will reduce the cost of machining greatly.
Wide spectrum, a large field of view telescope system design small distortion
Author(s):
Jin Hui;
Hong-tao Ma;
Chang-xiang Yan;
Yuquan Zheng;
Hui-lin Jiang
Show Abstract
This applies to the design of a telescope system imaging spectrometer, imaging spectrometer for the characteristics of the telescope from the pre-and post-spectrometer components. Pre-telescope system parameters and imaging quality of the application of the imaging spectrometer is very important. This paper designed a spectral range of 1000nm ~ 2500nm, field of view of 28.1 ° × 0.3 °, a relatively large diameter of 1 / 4, 180mm focal length of the telescope system. Systems in a wide spectral 1000nm ~ 2500nm spectral range by the glass and two matching spectral correction of chromatic aberration, distortion control at 0.2%, to ensure good follow-up spectroscopy with the butt, this design can be used for aviation the large field, high-resolution imaging.
Influence of atmospheric pressure supplied on permittivity of air-film of aerostatic bearing
Author(s):
Min Li;
Yubing Zhang;
Dong-sheng Li
Show Abstract
Influence of atmospheric pressure supplied on permittivity of the air-film is researched based on the capacitive testing method of the air film thickness of aerostatic bearing. An experiment platform is designed. The experimental results illustrate that permittivity has significant negative correlation with atmospheric pressure which varies from 0.1MPa to 0.48MPa when other environmental conditions remain unchanged. The curves conform to the fourth-order polynomial approximately. All of the values of R2 are beyond 0.944 which means that trend lines fit the data curves well. Relative permittivity of the air film is between 0.996 and 1.324. This interval shows that weak current exists between restrictor and flat of the experiment which are not absolutely insulating and atmosphere of the air film is not pure. This result provides a basis both for establishing accurate mathematical model of air film thickness and capacitance value of the aerostatic bearing and for other exploratory experiments later.
Measuring method for contour of object in complex high temperature variation environment
Author(s):
Yajun Liang;
Yinxiao Miao;
Xiaohui Chen;
Zengyu Sun
Show Abstract
The real-time measurement for contour of object would be influenced by many environmental factors when it is taken in complex temperature variation environment. The influence must be eliminated to get effective and accurate measuring results. A new measuring method based on binocular stereo vision is presented. The spectral property of high temperature object is analyzed and adaptive optical band pass filter is designed according to the spectrum. Then the gray value of image is adjusted to get clear images for satisfying the measuring requirement under special conditions.
Two-step method for measuring gear pitch deviation
Author(s):
Zhifeng Lou;
Haizhao He;
Baoyu Guo;
Siying Ling
Show Abstract
Closure technique for measuring gear pitch deviation was proposed by PTB and NMIJ, which can eliminate systematic error in pitch measurement. In closure technique method, the gear’s position was changed repeatedly, and pitch deviations were also measured. Through processing measurement data, the systematic errors in pitch measurement can be eliminated. Two-step method for measuring pitch deviation was introduced in the paper, in which position of the gear was changed only two times, and the systematic error can be also eliminated. A gear’s single pitch deviation was measured when closure technique and two-step method were used respectively, and difference of two measurement results was 0.15μm.
Gun bore flaw image matching based on improved SIFT descriptor
Author(s):
Luan Zeng;
Wei Xiong;
You Zhai
Show Abstract
In order to increase the operation speed and matching ability of SIFT algorithm, the SIFT descriptor and matching strategy are improved. First, a method of constructing feature descriptor based on sector area is proposed. By computing the gradients histogram of location bins which are parted into 6 sector areas, a descriptor with 48 dimensions is constituted. It can reduce the dimension of feature vector and decrease the complexity of structuring descriptor. Second, it introduce a strategy that partitions the circular region into 6 identical sector areas starting from the dominate orientation. Consequently, the computational complexity is reduced due to cancellation of rotation operation for the area. The experimental results indicate that comparing with the OpenCV SIFT arithmetic, the average matching speed of the new method increase by about 55.86%. The matching veracity can be increased even under some variation of view point, illumination, rotation, scale and out of focus. The new method got satisfied results in gun bore flaw image matching. Keywords: Metrology, Flaw image matching, Gun bore, Feature descriptor
Porcelain three-dimensional shape reconstruction and its color reconstruction
Author(s):
Xiaoyang Yu;
Haibin Wu;
Xue Yang;
Shuang Yu;
Beiyi Wang;
Deyun Chen
Show Abstract
In this paper, structured light three-dimensional measurement technology was used to reconstruct the porcelain shape, and further more the porcelain color was reconstructed. So the accurate reconstruction of the shape and color of porcelain was realized. Our shape measurement installation drawing is given. Because the porcelain surface is color complex and highly reflective, the binary Gray code encoding is used to reduce the influence of the porcelain surface. The color camera was employed to obtain the color of the porcelain surface. Then, the comprehensive reconstruction of the shape and color was realized in Java3D runtime environment. In the reconstruction process, the space point by point coloration method is proposed and achieved. Our coloration method ensures the pixel corresponding accuracy in both of shape and color aspects. The porcelain surface shape and color reconstruction experimental results completed by proposed method and our installation, show that: the depth range is 860 ∼ 980mm, the relative error of the shape measurement is less than 0.1%, the reconstructed color of the porcelain surface is real, refined and subtle, and has the same visual effect as the measured surface.
Modeling and analysis of a scanning electrostatic force microscope for surface profile measurement
Author(s):
Zhigang Jia;
Shigeaki Goto;
Keiichiro Hosobuchi;
So Ito;
Yuki Shimizu;
Wei Gao
Show Abstract
This paper presents the analysis of a prototype scanning electrostatic force microscope (SEFM) system developed for noncontact surface profile measurement. In the SEFM system, with a dual height method, the distance between the probe tip and the sample surface can be accurately obtained through removing the influence of the electric field distribution on the sample surface. Since the electrostatic force is greatly influenced by the capacitance between the probe tip and the sample surface, a new approach for modeling and analysis of the distribution of capacitance between the probe tip with an arbitrary shape and the sample surface with a random topography by using the finite difference method (FDM) is proposed. The electrostatic forces calculated by the FDM method and the conventional sphere-plane model are compared to verify the validity of the FDM method. The frequency shift values measured by experiment are also compared with the simulation results computed by the FDM method. It has been demonstrated that the electrostatic force between arbitrary shapes of the probe tip and the sample surface can be well calculated by the finite difference method.
System for contactless gauge blocks measurement
Author(s):
Zdeněk Buchta;
Šimon Řeřucha;
Břetislav Mikel;
Martin Čížek;
Josef Lazar;
Ondřej Číp
Show Abstract
This paper presents a novel principle for contactless gauge block measurement using a combination of low-coherence interferometry and laser interferometry. The experimental setup combines a Dowell interferometer and a Michelson interferometer to ensure a gauge block length determination with direct traceability to the primary length standard. This setup was designed for contactless complex gauge block analysis providing information about gauge block length, gauge block faces surface profile (e.g., indication of scratches) and by analysis of the interference fringes shape, also about the gauge block edge flatness distortion. The designed setup is supplemented by an automatic handling system designed for a set of 126 gauge blocks (0.5 mm to 100 mm) to allow the automatic contactless calibration of the complex gauge block set without a human operator.
Circular trajectory motion control of an inspection spherical robot
Author(s):
Bo Zhao;
Lei Wang
Show Abstract
A two pendulums driven spherical robot is designed for pipe inspection tasks in this paper and a circular trajectory motion control method is proposed. Compared with the traditional pendulum driven spherical robot, the improved two pendulums drive unit offers novel motion principle of circular trajectory motion which is studied by force analysis. Considering the motion characters, the circular trajectory motion is decomposed into forward roll and lateral roll, and the dynamics model is built based on the theorem of moment of momentum. In order to acquire the controllable velocity and radius of circular trajectory motion, a circular trajectory motion control strategy is proposed, by which the motion of one pendulum is planned according to the sine function to control the angle between the outer shell of the robot and the ground, and the motion of the other pendulum is controlled by position servo control to maintain the forward velocity of the robot. The controller of circular trajectory motion is designed for accurate tracking of the tile angle of the two pendulums, and the control strategy is validated by both numerical simulation and prototype experiment.
Passive ultrasonic apparatus for three-dimensional position
Author(s):
Liang Yu;
Fangfei Lin;
Ding Ma;
Mingji Yang;
Haibin Wu
Show Abstract
In this paper, a passive ultrasonic method for 3-D position is introduced, based on TDOA (Time Difference of Arrival). In the method, the distances between the ultrasonic source and receivers are calculated through measuring the differences between of the arrival times when the ultrasonic from the measured target reaches the ultrasonic receivers in different location, and the 3-D position is realized. Our method avoids the disadvantages of the current approaches: exactly recoding times of the ultrasonic emission and receipt, and the synchronization timing of the emitter and receiver. In this method, the 3-D position can be realized as long as the target has the ultrasonic source that can be accepted by the receivers. Thus, this method could achieve 3-D position of the non-cooperative targets, which can be applied in broader fields, especially in military. This paper not only established the mathematical model of the method and analyzed its design keys, but also came up with the design example as well as its simulation. Both of the theoretical analysis and experimental results show that position range is 50m(x)×50m(y)×50m(z) and position accuracy is 0.1m(x)×0.1m(y)×0.3m(z). So the method and apparatus are feasible and effective.
Design and testing of alterable preload running-in system of solid lubricated bearings
Author(s):
Jianwei Wu;
Hefan Zhao;
Jiwen Cui
Show Abstract
The lubricating mechanism and improved performances of MoS2 film in bearings is analyzed in this paper. In order to improve the performance of solid lubricated bearings, the running-in is necssary. The design of the running-in system which can change the bearing preload during the process of running-in is introduced in detail. The results of the running-in experiments are analyzed.
Electromagnetic methods for corrosion under paint coating measurement
Author(s):
Hong Zhang;
Gui Yun Tian;
Anthony Simm;
Mohammed Alamin
Show Abstract
Corrosion under coating has a serious effect on the metal conductivity and corrosion layer permittivity. A high frequency (13.56 MHz) Radio Frequency Identification (RFID) based system has been developed to measure corrosion under coating. The corrosion behaviour of coated steel has been investigated from a very fundamental understanding of permittivity using a Vector Network Analyser (VNA). This paper will first review corrosion and dielectric property measurement methods and investigate RFID tag antenna responses under different material properties of corrosion samples with atmospheric exposure times using VNA. The purpose of this study was to examine the RFID system for corrosion detection. The RFID tag’s coil and VNA are employed to measure the impedance change to determine the conductivity and relative permittivity variance with different atmospheric exposure times (1 month, 3 months, 6 months, 10 months and 12 months). Different spectrum distributions under different corrosion samples are investigated. Based on the studies, VNA based system testing, phase responses from the mild steel samples with different coating thickness are measured. The experimental results show that these two introduced techniques are able to distinguish between different exposure times with coating. Based on the results, corrosion detection under coating using equivalent permittivity and conductivity are developed and evaluated. Preliminary results show that the high frequency (HF) RFID method can be extended to a new application for detection of corrosion under coating and development of HF RFID systems for corrosion monitoring. Dielectric probe is applied to measure the permittivity variance with different paint thickness. With the paint thickness increasing, the dielectric is getting close to the paint’s properties. Waveguide is using here to measure the paint thickness effect for further UHF RFID study.
3D measurement based on phase-shift and self-calibration
Author(s):
Liangzhou Chen;
Yongjie Xu;
Dan Xiao
Show Abstract
Non-contact three-dimension (3D) measurement technology has developed rapidly. Digital grating projection is regarded as the best prospect one. There are many problems, such as low accuracy, which have not been solved yet. Based on digital grating phase-shift, and combed with height-phase mapping and self lattice calibrating, a new 3D measurement method has been proposed. With little geometric constraints to digital grating and CCD, the measurement system is more feasible, which can be used to realize the accurate measurement and reconstruction according to the 3D information from measured object. By applying the method proposed to a reference object, the experience has lead to good result which shows that the new method is efficient and precision.
Stitching for a large area of surface topography analysis of diamond grinding wheel
Author(s):
Shuang Wang;
Changcai Cui;
Chunqi Huang;
Hui Huang;
Ruifang Ye;
Shiwei Fu
Show Abstract
It is necessary to stitch small area of images together for large surface analysis while the measurement instrument used with a limited measurement area, e.g. White-light Interferometry (WLI)-based system. A new stitching method is proposed in this paper for diamond grinding wheel surface analysis. The images are captured by a WLI-based system and the 3D images’ stitching requires an overlapping region of 30%~50%. First, two-step intensity correlation matching method is used to obtain several pairs of matched points fast and the RANSAC (Random Sample Consensus) algorithm is adopted to screen them to get exact pairs of matched points. Then the measurement errors are adjusted and a stitched topography is got after data fusion. Experiments show that this method can effectively stitch 3D images of diamond grinding wheel together in less than 4 minutes with a correlation coefficient above 0.9 for two horizontal overlapping regions after adjustment.
Automatic positioning method based on feature points matching for ICF target
Author(s):
Bing-guo Liu;
Guo-dong Liu;
Na Gong;
Feng-Dong Chen;
Zhi-tao Zhuang
Show Abstract
This paper persents an laser and target alignment sensor (LTAS) used to automaticlly position for the ICF experimental target. LTAS which is based on optical conjugate principle can locate the targets online with its four imaging measurement systems. For the requirement of automatic positioning, presents a new method which is called offline test and online match method. With the help of target offline test device, the reference image features are provided, online images and reference images are matched in real time based on images point features, SIFT descriptors are used for extracting target feature from image which is invariant features to image scale and rotation. According to image feature, we modify the original feature vectors with 128 dimensions to a feature vectors with 32 dimensions. A fast nearest neighbor algorithm is used for feature match, and the Best-Bin-First (BBF) algorithm is used to search nearest neighbors of points, and then RANSAC algorithm is used to remove the mismatch points, A least-squares solution is used to calculate parameters between the reference image and the online image, according to the matching parameters, the target is automatic adjusted to proper attitude. By matching experiment, the position matching accuracy is within 1 μm, the angle matching accuracy is within 0.1 degree, matching time cost is less than 1 second, and meets the real-time matching requirements.
Long working distance autocollimating and microscope monitoring instrument
Author(s):
Bing-guo Liu;
Guo-dong Liu;
Na Gong;
Feng-dong Chen;
Zhi-tao Zhuang
Show Abstract
In the laser inertial confinement fusion (ICF) experiment, the high accuracy target field coordinate system should be found to monitor the target by all kinds of physics diagnose instrument. Before the testing target is shot, the coordinate system should be transferred to the testing target, and recurrent the coordinate system before each shooting. In order to solve this problem, two set microscope optics vision instruments are designed which has autocollimating and target position monitoring functions, and its working distance is 3.8 meters，and its optic resolution is 8 micron. Firstly, the optical coordinate axis of the two instruments is adjusted orthogonally by each other, then the ICF range coordinate is transferred to a testing target by a sensor, and ensure testing target located at the center of ICF range coordinate. The instrument has already been used in Shen Guang III device, and also can be used for object monitoring and tracing in a kind of field.
Standard equipment for pattern approval field test of vehicle speed-measuring devices for traffic law enforcement in China
Author(s):
Lei Du;
Qiao Sun;
Changqing Cai;
Yue Zhang;
Hongbo Hu
Show Abstract
Traffic speed enforcement is an important issue in order to guarantee public road security and to reduce the number of traffic accidents. Currently, this task has been partially carried out by vehicle speed-measuring devices, mainly including Doppler radar, lidar and inductive loop in China. To further evaluate the speed measurement performance of these devices widely used for evidentiary purposes in traffic speed enforcement cases, a traffic speed measurement standard equipment has newly been set up at No.S16 Expressway from Hangzhou to Shanghai in China. The standard equipment can be used for pattern approval field tests of vehicle speed-measuring devices in actual traffic, which can meet the requirements of the recommendation in OIML R 91 about the metrological field tests, with the advantage of the overall experiments of possible errors due to the complexity of factors affecting the result of measurement, such as shape of antenna pattern, reflection characteristics of target vehicle, change of lane during target vehicle passage through measurement region, braking or accelerating, presence of more than one vehicle, etc. This paper introduces the speed measurement principle of three kinds of vehicle speed-measuring devices, and studies the components of the standard equipment. A field testing experiment based on the standard equipment in actual traffic was designed and performed with 11 types of vehicle speed-measuring products as samples, including radar, lidar and inductive loop based devices, to evaluate their actual performances in actual traffic.
Rapid test apparatus of solid-state lithium-ion batteries
Author(s):
Zijun Wang;
Zhaoxuan Zhu;
Yuhong Ma;
Fuhe Yang
Show Abstract
This paper describes a rapid test apparatus that can be used to derive parameters of solid-state lithium-ion batteries. The test-procedure can operate in several modes such as constant-current and constant-voltage. It comprises voltage, current and temperature measurements during usage. The internal resistant test method of the battery is improved. The internal resistance in the application of lithium-ion batteries on line detection system is also designed in this apparatus. The paper also presents test data for a commercial battery including ageing effects.
Design of a silicon carbide neutron sensor
Author(s):
Qing-Qing Hu;
Jun Yang;
GuoFu Liu;
Xiao-liang Luo
Show Abstract
The radiation detectors based on the third era semiconductor material silicon carbide (SiC) with wide energy band gap are the most promising ionizing radiation detectors in high temperature and harsh radiation environment. This paper illustrated several important advantages of the SiC neutron detector and described its fabrication and detection principle briefly. Furthermore, we evaluated the neutron sensor’s measurement performance when detecting the 2.5MeV and 14MeV neutrons under different conditions of sensor’s active layer thickness and polyethylene converter film thickness based on MCNP simulation. According to the results of simulation, the sensor’s optimal configuration was designed. For the sensor whose radius and depletion layer thickness are 3mm and 30μm respectively, the detection efficiency can reach 3.16×10-18 coulomb per neutron (c/n) and 1.80×10-17 c/n for 2.5MeV and 14MeV neutrons respectively. When adding a polyethylene converter film of 90μm thickness to the above sensor, the detection efficiency to 2.5MeV neutron will be 3.7 times that without neutron converter film; and with the converter film of 2mm thickness, the detection efficiency to 14MeV neutron will be improved by 246%.
Measurement system and precision analysis for thermal regulating properties evaluation of textile materials
Author(s):
Bao-guo Yao;
Li-xia Yan;
Yi Li
Show Abstract
A new test method and a measurement system FTRT (Fabric Thermal Regulating Tester) has been developed to evaluate the thermal regulating properties of textile materials such as fabrics treated with PCM (Phase Change Material) microcapsules. The measurement system and the test method can measure the temperature, heatflux and displacement signals that can give an overall evaluation for the fabric thermal regulating properties. Derived from the test data, a series of indices are defined to characterize the thermal regulating properties. The test and evaluation method, the experimental setup and the gage capability analysis of the measurement system are reported. The analysis of the variance for intra laboratory test was performed to determine the precision of the test method and the measurement system. The measurement system FTRT provides a method for objective measurement and evaluation of thermal regulating properties of textile materials.
Measurement and correction method of the system time offset of multi-mode satellite navigation
Author(s):
Lin Zhu;
Huijun Zhang;
Xiaohui Li;
Longxia Xu
Show Abstract
Multi-mode satellite navigation is an important development direction of Global Navigation Satellite Systems (GNSS). Because of each satellite navigation system owing an independent and stable operating system time scale, one of key issues that must be solved to implement multi-mode navigation is to determine the system time offset between two satellite navigation systems. National Time Service Center (NTSC) keeps our country’s standard time (UTC (NTSC)). It is an available resource for us to monitor the system time offset of satellite navigation systems by means of receiving signal-in-space using the geodetic time receiver. The monitoring principle and main measurement errors are discussed. The correction method of system time offset measuring results is studied with the IGS precise orbit ephemeris. In order to test rationality of the measurement method, circular T bulletin data published by Bureau International des Poids et Mesures (BIPM) is applied to compare with the monitoring data and revised data. Data Processing results are given and shown that this monitoring method is practical and can be applied to multi-mode navigation.
Grain edge detection of diamond grinding wheel
Author(s):
Lijun Zhou;
Changcai Cui;
Chunqi Huang;
Hui Huang;
Ruifang Ye
Show Abstract
The topograpgy characterization of grinding wheel grain is indispensable for precision grinding, it depends on accurate edge detecting and recognition of abrasive grains from wheel bond to a large extent. Due to different reflective characteristics arising among different materials, difference between maximum and minimum intensity (Δ ) of diamond is larger than that of bond. This paper uses a new method for grain edge detection of resin-bonded diamond grinding wheel that combines the improved Canny operator in Method of Maximum Classes Square Error (called as OTSU) with ΔI obtained by the white light interferometry (WLI). The experimental results show that the method based on improved Canny operator can effectively detect the edge of diamond grain.
Visual detection of subsurface defects using enhanced magneto-optic imaging system
Author(s):
Yu Hua Hua Cheng;
Xingmake Liu;
Gui Yun Tian;
Libing Bai
Show Abstract
An enhanced magneto-optic (MO) imaging system is presented to detect the invisible and buried subsurface flaws in
metallic specimens. The choice of the MO thin films, the design of the magnetic excitation device and the development
of the image processing approaches are presented in this paper and the quality improvement in MO imaging has been
demonstrated due to the proposed methods. Experimental results have been provided and verify the reliability and
accuracy of the enhanced MO imaging system.
Intelligent transient transitions detection of LRE test bed
Author(s):
Fengyu Zhu;
Zhengguang Shen;
Qi Wang
Show Abstract
Health Monitoring Systems is an implementation of monitoring strategies for complex systems whereby avoiding catastrophic failure, extending life and leading to improved asset management. A Health Monitoring Systems generally encompasses intelligence at many levels and sub-systems including sensors, actuators, devices, etc. In this paper, a smart sensor is studied, which is use to detect transient transitions of liquid-propellant rocket engines test bed. In consideration of dramatic changes of variable condition, wavelet decomposition is used to work real time in areas. Contrast to traditional Fourier transform method, the major advantage of adding wavelet analysis is the ability to detect transient transitions as well as obtaining the frequency content using a much smaller data set. Historically, transient transitions were only detected by offline analysis of the data. The methods proposed in this paper provide an opportunity to detect transient transitions automatically as well as many additional data anomalies, and provide improved data-correction and sensor health diagnostic abilities. The developed algorithms have been tested on actual rocket test data.
Analysis of measurement grid in quantitative assessment of micro damage
Author(s):
Hongjuan He;
Dixiang Chen;
Mengchun Pan;
Ying Tang;
Jianqiang Zhao
Show Abstract
Micro damage on metal surface will cause the change of conductivity. By accurately measuring conductivity, quantitative assessment of micro damage can be achieved accurately. Planar electromagnetic sensor could be used to obtain conductivity through measurement database which relates sensor response to conductivity, the property of material under test. Measurement grid is graphical database, and its features have significant influences on measuring precision and speed. However, there are few studies on grid features of planar electromagnetic sensor. This paper analyses how the conductivity error is influenced by three features of grid unit, and presents the relationship between them, which could be used to optimize the database.
Uncertainty evaluation study on Chang’E-1 Laser Altimeter on-orbit detection error
Author(s):
Dong-Xia Wang;
Ai-Guo Song;
Xiu-Lan Wen
Show Abstract
The Chang’E-1 Laser Altimeter(LAM), as one of the scientific instruments onboard the Chinese Chang’E-1 orbiter, has successfully gained the massive lunar elevation scientific data of global topography of the moon. Uncertainty evaluation of the lunar elevation detection error based on LAM scientific data is developed in this paper. Firstly, the data are selected from the flat terrain region in all the lunar elevation detection data; Secondly, after the pseudo elevation data are removed in the selected region, regional elevation mean and standard deviation are calculated. Making use of the calculations and taking into account all kinds of uncertainty contributors of LAM orbiting exploring, the uncertainty evaluation methods of the LAM in-orbit elevation exploring are proposed on the basis of the guide to Monte Carlo Methods. Finally, the uncertainty evaluation results of different regions of lunar surface are given. The evaluation results not only can provide the basis for further analysis laser altimeter measurement error sources, but also give the reference for making the high precision moon digital elevation graph and provide theoretical guidance for the accuracy requirement of design of payload on lunar orbiter.
Design of RF source based on Direct Digital Synthesizer
Author(s):
Hui Liu;
YueHong Qiu
Show Abstract
A new Radio Frequency (RF) source based on Direct Digital Synthesizer (DDS) is presented in this paper, to improve the performance of the Sound-light tunable filter. A DDS chip called AD9959 is used to produce RF signal. The AD9959 consists of four DDS cores that provide independent frequency, phase, and amplitude control on each channel, and FPGA is used to control AD9959, to ensure a high accurate signal source with multiple signal mode and four channels output is designed. This paper introduces the implementation of system including software and hardware. The test results show that the RF source has 0-200MHz bandwidth and resolution, stability and a series of functions fully realize the scheduled target.
Novel measurement principle of profile deviations evaluated through double-flank rolling test with rack probe
Author(s):
Jie Tang;
Zhaoyao Shi;
Zhiqiang Fang
Show Abstract
Generally the profile deviations are measured through the generating method, the coordinate method and the meshing method by using gear measuring instruments (GMI) and coordinate measuring machines (CMM) in metrology room. But high-speed inspection of gear profile deviations at industrial scale manufacturing is a problem. To solve this problem, a novel measurement principle of profile deviations based on the double-flank rolling test with rack probe is introduced in this paper, and also the measuring system was given. The new methods will meet the demands of the high-speed gear measurement in shop floor.
Analysis of non-idealities of low-pass filter in random demodulator
Author(s):
Jingchao Zhang;
Ning Fu;
Wei Yu;
Xiyuan Peng
Show Abstract
Random Demodulator (RD) is a novel signal acquisition scheme based on compressed sensing (CS). It is able to acquire signals continuous in time and sparse in frequency at a sampling rate far below the Nyquist frequency. In the RD architecture, low-pass filter plays a role of anti-aliasing and is also the main part of the measurement matrix which should be characterized accurately. In this paper, we analyze the impact of the low-pass filter’s non-idealities. If the filter parameters deviate from their ideal values, there will be mismatch between the ideal impulse response used in the measurement matrix and the practical, which will degrade the reconstruction performance. The results show that with the increase of the degree of mismatch, the quality of signal reconstruction, measured by signal to noise ratio (SNR), declines. The results suggest accurate calibration is needed in practical use.
Wireless communication in the airflow verification system of biological safety cabinet
Author(s):
Yu-de Zhang;
De-xin Hou;
Jian Qiu;
Shu-liang Ye
Show Abstract
In recent years, biological safety cabinet has been applied widely and urgently to the biochemistry laboratory. An increasing research need has been asked about the processing safety of the workers. In this safety cabinet system, among series of related factors, the main parameter is airflow velocity. At percent, this measuring work is usually done by processional workers, thus leading to the low efficiency and disadvantages. In this paper, a new method was approved to deal with the current problem, where wireless communication controller and detector. According to the experimental data and the comparison between the two methods, the wireless way is more convenient and more efficient than previous one, and the working distance can be about 730 meters. Meanwhile, the communication system has already been used in Guangzhou Institute of Metrology Laboratory.
Echo power analysis and simulation of low altitude radio fuze
Author(s):
Xiaolu Chen;
Biao Chen;
Tao Xu;
Suqin Xu
Show Abstract
The echo power from the earth gound which was received by fuze plays an important role in aerial defense missile, especially when the fuze is working in the look down mode. It is necessary to analyze and even simulate the echo power signals to enhance the missile’s anti-jamming ability. In this paper, the quantity of echo power from the earth ground of low altitude radio fuze was analyzed in detail. Three boundary equations of area irradiated by electromagnetic beams were presented, which include two equidistant curve equations and one equal-Doppler curve equation. The relationship between the working mode and the critical height was analyzed. The calculating formula of echo power waveform was derived. And based on the derived formula, the correlation between the maximal echo power and the incident height was given and simulated, which would be helpful for the further researches of low altitude radio fuze.
A simple line sensing method by laser line scanning for line scale measurement
Author(s):
Hongtang Gao;
Xiaoyou Ye;
Jianshuang Li
Show Abstract
Line sensing is key for line scale measurement. Different methods for line sensing are suited to different Line Scales.
Line sensing methods such as CCD microscope and slit photoelectric microscope currently mainly used in the world are
introduced. This paper presents a new method based on laser line scanning technique, which is widely used in laser bar code scanner. The basic sensing principles, the precision can be obtained with different methods and the advantages and disadvantages of the methods are also discussed. An experiment device based on laser line scanning was built to measuring the ordinary line scale such as square rules, steel tapes. In order to get a good reproducibility for line sensing, the line signal processing is studied. The line position is calculated as mass center of certain areas above minimum value of each line signal, the experiment result shows that when measuring 1mm interval of an ordinary steel ruler in scanning interval 10μm, the reproducibility is less than 1μm.
A new type apparatus for measuring inner diameter based on inductive transducer and its mathematical model
Author(s):
Jingqi Sun;
Liandong Yu;
Teng Ye
Show Abstract
The measurement of inner diameter is a traditional and important measurement task in machining. Methods to measure the inner diameter are divided into contact and non-contact measurement. A contact measurement method with multiple inductive transducers is presented in this paper. In this paper, the constitution and structure of the system are described in order to establish the mathematical measurement model and analyze the measurement error emerged by inaccurate parameters. Moreover, the outputs measured by sensors are transformed into corresponding coordinates, and then the least square method is adopted to fit the coordinates to calculate the diameter, details will be presented in the paper. The measuring accuracy of the system is verified by experiment. The results indicate that this method could reduce the error caused by sensors deviated from the center of measuring circle and improve the measurement accuracy.
Digital processing of RF signals from optical frequency combs
Author(s):
Martin Cizek;
Radek Smid;
Zdeněk Buchta;
Břetislav Mikel;
Josef Lazar;
Ondřej Cip
Show Abstract
The presented work is focused on digital processing of beat note signals from a femtosecond optical frequency comb. The levels of mixing products of single spectral components of the comb with CW laser sources are usually very low compared to products of mixing all the comb components together. RF counters are more likely to measure the frequency of the strongest spectral component rather than a weak beat note. Proposed experimental digital signal processing system solves this problem by analyzing the whole spectrum of the output RF signal and using software defined radio (SDR) algorithms. Our efforts concentrate in two main areas: Firstly, using digital servo-loop techniques for locking free running continuous laser sources on single components of the fs comb spectrum. Secondly, we are experimenting with digital signal processing of the RF beat note spectrum produced by f–2f 1 technique used for assessing the offset and repetition frequencies of the comb, resulting in digital servo-loop stabilization of the fs comb. Software capable of computing and analyzing the beat-note RF spectrums using FFT and peak detection was developed. A SDR algorithm performing phase demodulation on the f– 2f signal is used as a regulation error signal source for a digital phase-locked loop stabilizing the offset frequency of the fs comb.
The micro-thrust automatic measurement system of stationary plasma thruster
Author(s):
Jing Li;
Hong-wie Mei;
Geng Wang
Show Abstract
We describe the micro-thrust automatic measurement system of stationary plasma thruster in the article, The system
can carry a thruster and power supply less than 3kg weight. Thrust capacity is from 1 to 100 mN,and thrust expend
uncertainty is 0.2 mN（k=2）.The system is based on the torsion balance principle. The thrust of the thruster makes torque
to the pivot. This torque is balanced by the electromagnetic compensate torque generated by the measurement system.
The rotation angle of this system is measured by the position sensor, the electromagnetic interference single comes from
the speed sensor, the electromagnetic compensate torque is from the torque sensor. This is a closed circuit and automatic
measurement system. The additional forces generated by the weight, the air supply system and the wires of the thruster
have been separated from the micro-thrust in this system. The influence of deadweight, air supply system and power
supply system of thruster on exact measurement of micro-thrust have been eliminated, so micro-thrust of thruster can be
measured precisely and automatically.
Radius measurement using two-windows common-path interferometry with phase grating
Author(s):
Bengong Hao;
Ming Diao;
Zhi Zhong;
Mingguang Shan;
Yabin Zhang;
Shulei Lang
Show Abstract
A method using two-windows common-path interferometry with phase grating is presented to measure the curvature
radius (CR). This interferometry is built using a 4f optical system with binary phase grating implemented by spatial light
modulator (SLM) as spatial filter. The input plane is formed by two windows, which are used for the measured lens and
reference beam, respectively. In the output plane, an interferogram can be achieved by a proper choice of the windows’
spacing with respect to the grating period. The phase of the lens can be retrieved from the shift phase of composite
interferograms achieved by lateral movements of the grating. The curvature radius of the lens is thus directly derived
from the phase function. A theoretical model is also established using Fourier transform theory and phase retrieval
algorithm to describe the measured process using phase-shifting interferometry. Analyzed results indicate that the
method is an effective approach for the radius measurement with inherent simplicity, high robustness and flexibility.
Polarization-sensitive white light interferometer with an autofocus device
Author(s):
Rong-sheng Lu;
Jing-tao Dong;
Lin Chen;
Yan-qiong Shi;
Rui-xue Xia
Show Abstract
A polarization-sensitive white light interferometer (PSWLI), which is a promising technique that can be used to measure the stress induced birefringence, is developed. The use of wide-spectrum light source brings to PSWLI a resolution in the micron range, but the difficulty arises when searching for the best fringe contrast within the extremely short coherence length, especially for the Linnik interference configuration. To tackle this problem, an autofocus device based on the improved astigmatic method is embedded in the PSWLI system to firstly automatically determine the best foci of the reference mirror and the test sample. Then the minimization of optical path difference (OPD) of two interference arms are implemented by the root mean square fringe contrast function combined with a 4×4 pixel binning of the CCD camera. The autofocus time is no more than 0.3 second and the minimization of OPD has a speed of 2.2 min/mm. Finally, the developed PSWLI system is calibrated by the Berek compensator and the birefringence measurement result is obtained by simultaneously calculating the phase retardation, the optical axis orientation, the reflectance and the stress map of a stress induced birefringence sample.
focusing by an arbitrary opening paraboloid mirror and its application in confocal scanning microscopy
Author(s):
Tao Liu;
Jiubin Tan;
Yuhang Wang;
Wang Chao;
Jian Liu
Show Abstract
Focusing of the plane wave with radially polarized electric field by an arbitrary opening paraboloid mirror is analyzed
using a rigorous vectorial diffraction theory, i.e., Stratton-Chu integral. In the vicinity of the focus, far-field
approximation conditions are used to simplify the derived integrals with sufficiently high accuracy. It is found that a
noticeable deviation of the approximate integral, as characterized by a phenomenon of focal shift, from the exact integral
can be observed when the maximum focusing semi-angle α below π/9. For α=π/2, the radial spot size reduces to below
0.40λ if cutting off the central segment, larger than π/4, of the paraboloid mirror. The sharp focusing property of the
paraboloid mirror has the potential application in super-resolution confocal scanning microscopy. Specific confocal
scanning arrangements are provided and remarked.
An approach to remove defocused aberration on array confocal microscope
Author(s):
Xiangdong Huang;
Tong Zhou;
Jingguo Jia
Show Abstract
In order to obtain a high resolution image required for ultra-precision measurement of microstructural object, a new approach is proposed for 3D microstructures. It uses the modulation transfer function with defocus aberration based on the ambiguity function and stable phase principle to achieve an optical phase filter, and utilizes generalized a spheric phase optical element to encode defocus images, and uses deconvolution technology to recover the images. In comparison with conventional optical system, the phase filter used in the optical system can make focal spot smaller when measure object defocusing, eliminates the effect of the defocus aberration, and improves the defocused property. Numerical results indicate the designed phase filter can improve lateral resolution of optical system, and the axial resolution of the optical system is not affect by the filter and defocus aberration. For different defocus plate, the phase filter can make character of modulation transfer function of lateral direction uniform approximation.
Scattering near specular direction for horizontally oriented ice discs
Author(s):
Zhile Wang;
Yin Zhang;
Yiming Cao;
Mingyu Cong;
Wenzhuo Bao;
Qingyu Hou
Show Abstract
Scattering phase function on horizontally oriented ice particles near the specular reflective direction is analytically modeled using a mixed method combining direct reflection and Fraunhofer diffraction components, where particles are simply treated as circular facets and the effect of fluttering is introduced under the assumption of Gauss distribution. The obtained model expression reveals that the essence of far-field scattering around specular direction is the diffraction pattern modulated by fluttered geometric reflection. Four groups of experiments are designed to validate this model at different wavelengths and incidence angles, and the calculated phase functions present good agreement both in distributions and peak values with that of T-matrix method in conjunction with a Monte Carlo stochastic process.
A high sensitive roll angle interferometer
Author(s):
Yanfen Le;
Wenmei Hou;
Kai Hu;
Aisong Ju
Show Abstract
A roll angle interferometer with high sensitivity is designed in this paper. Two sets of centrosymmetric beams are used to travel through the measurement and reference arms of the roll angle interferometer which contains two specific optical devices: wedge prism assembly and wedge mirror assembly. The optical path change in both arms caused by roll is converted into phase shift which can be measured by interferometer. Because of the adoption of the centrosymmetric measurement structure, the straightness errors, yaw error and pitch error can be avoided and the dead path is minimized, so that the stability and the accuracy of the measurement can be greatly enhanced. The resolution for the roll measurement is about 0.006″ with the measurement range of ±1°.
Constrained simultaneous stitching measurement for aspheric surface
Author(s):
Weibo Wang;
Zhigang Fan
Show Abstract
Significant errors could be result from multiple data sets due to error transfer and accumulation in each sub-aperture. The constrained simultaneous stitching method with error calibration is proposed to increase the stability of the numerical solution of the stitching algorithm. Global averaging error and constrained optimization are applied to simultaneous stitching after alignment errors calibrated. The goal of optimization and merit function is the minimization of the discrepancy between multiple data sets by including components related to various alignment errors. The values for stitching coefficients that fall within the unit sphere and minimize the mean square difference between and overlapping values can be found by iterative constrained optimization. At last, the full aperture wave-front was reconstructed by simultaneous stitching with the stitching coefficients required to remain within meaningful bounds.
The phase detection method in continuous monitoring of pH during the process of cell culture
Author(s):
Zemin Liu;
Wei Tao;
Hui Zhao;
Jinke Cheng
Show Abstract
The pH value has been one of the keen parameters in the cell culture. And the optical measurement method especially the optical method using optical fiber has been widely used due to its small volume and high accuracy. In this work we design a phase detection system to detect the phase difference between the signal and reference signal in the Dual Lifetime Referencing Method. The modulation frequency of the DLR method ranges from 10 kHz to 60 kHz and the system we designed can detect phase difference from the frequency of 1 kHz to 100 kHz. The error can be as small as 0.2%.
Optimal configuration for the dual rotating-compensator Mueller matrix ellipsometer
Author(s):
Weichao Du;
Shiyuan Liu;
Chuanwei Zhang;
Xiuguo Chen
Show Abstract
The dual rotating-compensator Mueller matrix ellipsometer based on the optical configuration PC1r(ω1)SC2r(ω2)A has been developed recently with many applications such as characterization of thin film growth and surface modification. In this paper, the optimal configuration of this ellipsometer is performed by minimizing the condition number of the systematic data reduction matrix. We present the optimal orientation angles of the polarizer (P) and the analyzer (A), as well as the optimal number of sampling points and the optimal retardance of both compensators, and find that these optimal configurations at different frequency ratios of the two compensators (C1r and C2r) yield almost equal performance. Simulations conducted on this ellipsometer with different parameters have demonstrated that the optimal configuration improves the measurement accuracy.
Fabrication of optical elements using a rapid UV-curable and low-viscosity polymer material
Author(s):
Man Zhang;
Zhiwei Li;
Xiaochun Dong;
Lifang Shi;
Qiling Deng;
Chunlei Du
Show Abstract
Polymer optical elements have widely been investigated because of their low cost and simple fabrication. Currently, UV-curable epoxy resins have been become general polymer materials for optical elements. However, they are still limited by their intrinsic properties, such as a relatively low rate of polymerization and high formulation viscosity. This paper proposed and demonstrated a rapid UV-curable process for polymer optical elements fabrication based on a UV-curable and low-viscosity thiol-ene composition. Several optical elements, including one-dimensional gratings with a 10-um period, Dammann Gratings and microlens arrays (100μm lens diameter), were fabricated by the UV-curable thiol-ene composition and their optical properties were examined in detail.
Alternate dual pulses technique for fiber Bragg grating Ultra-multi-point strain measurement
Author(s):
Xin Gong;
Dengxin Hua;
Pengbo Zhang;
Liaolin Hu;
Yufeng Wang
Show Abstract
The research of ultra-multi-point strain detection is one of the important topics at the forefront of optical fiber sensing technology. A newly ultra-multi-point strain measurement system was designed based on optical time-domain reflectometry (OTDR) and Fiber Bragg Grating. Two distributed feedback (DFB) lasers is proposed as laser source to generate the alternately pulsed light, and transmitted to a serial of fiber Bragg gratings with the same low-reflectivity and bandwidth. By the means of the strength of each reflectance spectrum and its return time of signals, the magnitude and location of strain can be accurately determined, and the numerical simulation shows that more than 1000 FBGs can be multiplexed in OTDR-FBG strain measurement system for a larger strain measurement range. Furthermore, the corresponding driving circuits for nanosecond pulse and temperature control circuits are designed for laser pulse modulation and frequency stabilization control. A OTDR-FBG strain measurement system is developed by using 10 FBGs with the reflectivity of less than 5%, and the system distance resolution of 43 cm is obtained, which verified the feasibility of the system.
Three-dimensional surface measurement by amplified off-axis digital holography
Author(s):
Wu You;
Xiaojun Liu;
Wenlong Lu;
Liping Zhou
Show Abstract
A new optical configuration for amplified off-axis digital holographic microscopy is presented and applied to surface measurement. By symmetrical configurations in the optical path, aberration compensation for phase curvature can be avoided in the reconstructed process. Three dimensional surface texture of a grating plate is reconstructed via a single hologram and its parameters are verified.
High-precision aspherical wavefront shaping with combined computer generated holograms
Author(s):
A. G. Poleshchuk;
R. K. Nasyrov
Show Abstract
The problem of design and fabrication of metrological standards of aspherical wavefronts and aspherical surfaces is considered. Method for wavefront shaping by computer-generated hologram (CGH) is presented. The wavefront errors caused by fabrication process of CGH, substrate nonuniformity and misalignment against interferometer are considered and discussed in details. Practical results of design and fabrication of amplitude and phase combined CGHs for shaping of two functionally independent wavefronts are presented. It is experimentally shown that errors of wavefront are localized within 0.01 wavelength. It is shown that hologram of this kind allows to subtract from measurements results substrate non-uniformity and fabrication error.
Filtering method for phase fringe patterns in the digital speckle pattern interferometry
Author(s):
Yonghong Wang;
Weihua Bu;
Junrui Li;
Jianfei Sun;
Lianxiang Yang
Show Abstract
The phase fringe patterns obtained by the phase shifting technique are inherently full of speckle noise in Digital Speckle Pattern Interferometry (DSPI),. The phase fringe patterns filtering method is very important to obtain the precisely deformation information. In this paper a effective method for filtering the speckle noise of phase fringe patterns is applied, the method filter the discrete images which generated from phase fringe patterns instead of classical filtering phase fringe patterns directly. Comparing with existed filters method, it has a better performance on phase jump information preservation and does not have any blurring effect on the phase distribution providing the filtering is implemented on the equal-phase window. Moreover, its capability of noise reduction is more powerful. An optical measurement system based on DSPI is built to demonstrate the filtering method, and the experiment results have shown the effectiveness and advantages of the filter method.
Image degradation of large-aperture R-C optical system induced by micro-vibration
Author(s):
Hongjuan Wang;
Wei Wang;
QiMin Liu;
Gang Li
Show Abstract
As part of the spacecraft optical loads, space camera will be subject to all working components in aircraft and space environment disturbance on-orbit, which have great influence on image resolution and image contrast, especially for large-aperture Ritchey-Chretien (R-C) optical system. This article puts forward a new method about estimating image quality degradation induced by micro-vibration. With the space coordinate transformation, the amount of optical elements jitter expressed by six variables are acquired, then the data can be imported to optical design software Code V, image motion and the root mean square(RMS) diameter will be quickly attained, then the image quality could be judged. The simulation and analysis are of significance for studying the influence of satellite micro-vibration on imaging system. For high resolution large-aperture R-C imaging system, this study provides important reference for system control and isolation.
Spectrally resolved chromatic confocal interferometry for one-shot nano-scale surface profilometry with several tens of micrometric depth range
Author(s):
Liang-Chia Chen;
Yi-Shiuan Chen;
Yi-Wei Chang;
Shyh-Tsong Lin;
Sheng Lih Yeh
Show Abstract
In this research, new nano-scale measurement methodology based on spectrally-resolved chromatic confocal interferometry (SRCCI) was successfully developed by employing integration of chromatic confocal sectioning and spectrally-resolve white light interferometry (SRWLI) for microscopic three dimensional surface profilometry. The proposed chromatic confocal method (CCM) using a broad band while light in combination with a specially designed chromatic dispersion objective is capable of simultaneously acquiring multiple images at a large range of object depths to perform surface 3-D reconstruction by single image shot without vertical scanning and correspondingly achieving a high measurement depth range up to hundreds of micrometers. A Linnik-type interferometric configuration based on spectrally resolved white light interferometry is developed and integrated with the CCM to simultaneously achieve nanoscale axis resolution for the detection point. The white-light interferograms acquired at the exit plane of the spectrometer possess a continuous variation of wavelength along the chromaticity axis, in which the light intensity reaches to its peak when the optical path difference equals to zero between two optical arms. To examine the measurement accuracy of the developed system, a pre-calibrated accurate step height target with a total step height of 10.10 μm was measured. The experimental result shows that the maximum measurement error was verified to be less than 0.3% of the overall measuring height.
Automatic measurement method of two-dimensional complex geometric features
Author(s):
Boxia He;
Yong He;
Fu-long Ren;
Rong Xue
Show Abstract
To realize automatic measurement of two-dimensional complex geometric features on parts with high-precision, the characteristics and advantages of five types of machine vision measurement methods are analyzed. The technological challenges that each method faces in dealing with high-precise automatic measurement of complex geometric features are indicated. To solve the problem, a machine vision measurement method with cooperation of multi field of view, which has a hierarchical structure, is proposed. Its principle and procedures are introduced. The experimental results show that the relative error is less than 0.025% using the method to gauge conventional scale parts. Its outstanding advantage is that the measuring accuracy is NOT influenced by ambient temperature and the precision of machine systems compared with traditional CMM. Therefore, it is an effective method that can be applied in industrial spot to automatically measure normal and large scale two-dimensional complex geometric characteristics with high-precision.
A contact probe using Michelson interferometers for CMMs
Author(s):
Chao-min Huang;
Bo-Hsun Liao;
Kuang-Chao Fan
Show Abstract
A high precision contact probe for a micro/nano-CMM was developed to detect the 3D motion of the stylus tip. This contact probe is composed of a stylus with a ball tip, a suspension plate and three displacement sensors. The stylus was connected to the suspension plate, which is suspended to the probe housing by three beryllium-copper leaf springs. A 3D translation of a ball tip causing by probing force would be transferred to three Z-displacements on the suspension plate. Displacement sensors, based on the classic model of Michelson interferometer, can measure nanoscale displacement on the plate. Calibrations with a nano measuring and positioning machine (NMM) proved the typical standard deviation was less than 20 nm for both the trigger and scanning modes.
The high-precision videometrics methods to determining absolute vertical benchmark
Author(s):
Jinbo Liu;
Zhaokun Zhu
Show Abstract
The mobile measurement equipment plays an important role in engineering measurement tasks and its measuring device is fixed with the vehicle platform. Therefore, how to correct the measured error in time that caused by swayed platform is a basic problem. Videometrics has its inherent advantages in solving this problem. First of all, videometrics technology is non-contact measurement, which has no effect on the target’s structural characteristics and motion characteristics. Secondly, videometrics technology has high precision especially for surface targets and linear targets in the field of view. Thirdly, videometrics technology has the advantages of automatic, real-time and dynamic. This paper is mainly for mobile theodolite.etc that works under the environment of absolute vertical benchmark and proposed two high-precision methods to determine vertical benchmark: Direct-Extracting, which is based on the intersection of plats under the help of two cameras; Benchmark-Transformation, which gets the vertical benchmark by reconstructing the level-plat. Two methods both have the precision of under 10 seconds by digital simulation and physical experiments. The methods proposed by this paper have significance both on the theory and application.
In situ chatter suppression in milling machines using microphone
Author(s):
Chao-Ching Ho;
Jin-Chen Hsu;
Chih-Hao Lien;
Ping-Yen Hsieh
Show Abstract
Chatter suppression in milling machines, using acoustic signals, is examined for preventing poor finishes and for
upgrading production quality. The technique of on-line acoustic signal analysis for suppressing chatter has been
examined in realistic milling experiments. The natural frequency was determined for end mills, based on finite element
analysis, so that beam equations could be used for chatter detection. Frequency domain analysis was employed to
monitor the shift in the dominant frequency. In this study, the acoustic chatter signal frequency and resonant peak were
applied using a feedback control loop to quantify the acoustic signal and to compensate for spindle speed, respectively.
Measurement of flexible temperature-pressure distribution for robot sensing skin
Author(s):
Qinghua Yang;
Ying Huang;
Siyu Wu;
Wei Miao;
Xiumei Liu
Show Abstract
The design of flexible pressure and temperature sensor array, which will serve as the artificial skin for robot applications, is presented. Different conductive rubber，which has different kinds of conductive filler, is employed as the pressure and temperature sensing material. The pressure sensing material is carbon black (CB)/multi-walled carbon nanotubes (MWCNTS)/silicon rubber, the proportion of CB and CNTS is 6% and 4%, respectively. The temperature sensing material is carbon fiber/silicon rubber; the proportion of carbon fiber (CF) is 12%. Both of the materials are flexible enough to use as artificial skin. Small disks of pressure and temperature conductive rubber are bonded on predefined flexible interdigital copper array. The pressure and temperature sensitive properties of the sensor array are measured. The structure of the sensor array make the temperature sensing material doesn’t take any interference of pressure. The separate collection of pressure and temperature signals with the scanning circuits can effectively reduce the crosstalk between each sensing element. With this integrated sensor array, the images of pressure and temperature distribution have been successfully shown by LabVIEW. This flexible sensor array can be bended without any influence of performance, so the sensor array is flexible and sensitive enough to be used as robot skin.
Iterative learning control for dual stroke actuator systems
Author(s):
Xiaoming Jiang;
Yan Wang;
Xin Li;
Yang Liu;
Xinglin Chen
Show Abstract
This paper presents a dual iterative learning control strategy for a dual stroke actuator system in the lithography scanner. The motion control strategy is employed, in which the trajectory of a short stroke stage is followed by one of a long stroke stage. A short stroke stage is used for improving the system response performance while a long stroke stage is introduced for the purpose of long motion stroke of the system. Combining the dynamic model of the system, the coupling effects between two actuators are analyzed, and the system model is simplified. This model is used for the design of a dual iterative learning control strategy and decoupling controllers. As a result, the heavy proportion of the recurrent coupling force on the long stroke stage is eliminated by the decoupling feedforward action from the output of the short stroke stage in the scanning process. The rest of the coupling force is removed by the first iterative learning control between two subsystems. The impact on the short stroke stage from the long stroke stage is weakened, and the short stroke stage is then designed independently by the two degree of freedom control strategy combining feedback control with the second iterative learning control. The convergence of the iterative learning control system is shown, and the effectiveness of the combined method is verified by a simulated wafer stage.
Design of readout IC for photoelectron detector of short-wave high frequency IRFPA
Author(s):
Pan Wang;
Rui-jun Ding;
Guo-qiang Chen;
Honglei Chen
Show Abstract
Design of readout-integrated circuit(ROIC) with high frequency and low signal for 512×256 short wavelength(SW) inferred-focal-plane-arrays(IRFPAs) is presented. The ROIC with high performance in frame rate can integrate and read out the low signal. An analog signal chain, which contains CTIA, CDS module, amplifier of charge and complementary output stage, can satisfy the high frequency and low signal application. A reliable digital control structure of IRFPA ROIC is presented, with which the integral voltage of arbitrary contiguous or noncontiguous lines, rather than regular lines, can be selected to readout. The simulation and verification are completed both before and after completing the layout. The circuit’s structure and operation principle are analyzed under the environment of mix-signal, and the result shows that the output dynamic range is over 2.5V, the charge capacity is more than 1Me-, the frame rate is 250Hz, the linearity within useful dynamic range is above 99.9 percent.
Nonlinear feedback control of dual-stage actuator system
Author(s):
Chuan Liu;
Yang Liu;
Xing Li;
Xing-lin Chen
Show Abstract
The wafer stage of lithography is a dual-stage actuator (DSA) system. An nm-level positioning precision is required by using macro movement of long-stroke linear motor and high-precision micro movement of short-stroke voice coil motor, while the platform is moving in high-speed. This brief presents a nonlinear control method for dual-stage actuator systems to track a step command input fast and accurately. To further reduce the settling time, we design the long-stroke actuator controller with the control law of proximate time optimal control (PTOC) to yield a closed-loop system with a small damping ratio for a fast rise time and certain allowable overshoot. Moreover, for the purpose of reducing the overshoot caused by the long-stroke actuator as the system output approaches the target location, a composite nonlinear feedback (CNF) control law is designed for the short-stroke actuator to yield a closed-loop system with a large damping ratio. The linear extended state observer (LESO) was designed to estimate the unknown velocity and compensate the disturbance of servo systems, thus static error could be effectively decreased. We applied this proposed control method to an actual DSA positioning system, which consists of a linear motor and a voice coil motor. Experimental results show that our approach can improve the dynamic performance and the anti-jamming capability of the system, enhance the control precision.
Delay error and compensation in measurement of micro-scale using aiming and triggering method
Author(s):
Ji-wen Cui;
Fu-ling Yang;
Jiu-bin Tan
Show Abstract
In order to improve accuracy of critical contacting position in measurement of micro-scale using aiming and triggering method, delay error of triggering signal, sampling delay error of sensor and length measuring device(double frequency laser interferometer) impact on accuracy are analyzed, compensation methods of solving nodal equation through establishing piecewise fitting function based on least square polynomial fitting and compute threshold triggering points through computing delay time are put forward. With this method, the measured diameter of micro-hole with nominal diameter Φ 0.3mm and depth 1.0mm is compensated. Results indicate that diameter of micro-hole after compensation increases 0.12 μm, closer to nominal value, and experimental standard deviation reduces by 0.069 μm. Therefore the measuring repeatability is improved, which demonstrates that the method is correct and effective.
Characteristic evaluation and experimental analysis of the ultrahigh precision three-dimensional scanning probe
Author(s):
Shuai Liu;
Zi Xue;
Shu-liang Ye;
Dexin Hou;
He-yan Wang
Show Abstract
Probe is the kernel component of the precision measuring instrument for the system accuracy which is determined by the probe characteristic. Three-dimensional scanning probe is an ideal choice for gear helical error measurement because it has both space coordinates points detecting capacity and scan capacity on the space of curves and surfaces. In order to make full use of the probe’s capacity and improve the measurement accuracy, characteristic evaluation of the probe is necessary before used. The static calibration equipment for the sensor has been established based on the high precision PZT micro displacement platform. Linear characteristic analysis and compensate of the ultra-high precision three-dimensional scanning probe has been done by this equipment, which greatly improved the accuracy of the probe. Finally, probe characteristic under working status is analyzed and experimentally verified which will be very helpful to compensate the probe errors.
Ultrasonic array imaging in nondestructive evaluation: total focusing method with using circular coherence factor
Author(s):
Jie Zhang;
Bruce W. Drinkwater;
Paul D. Wilcox
Show Abstract
Ultrasonic array imaging algorithms have been widely used and developed in non-destructive evaluation in the last 10 years. In this paper, a widely-used imaging algorithms, Total Focusing Method (TFM), was further developed with using the phase statistical information of the scattering field from a scatterer, i.e., Circular Coherence Factor (CCF). TFM and TFM with using CCF are compared through both simulation and experimental measurements. In the simulation, array data sets were generated by using a hybrid forward model containing a single defect amongst a multitude of randomly distributed point scatterers to represent backscatter from material microstructure. The number of point scatterers per unit area and their scattering amplitude were optimized to reduce computation cost. The Signal to Noise Ratio (SNR) of the finial images and their resolution were used to indicate the quality of the different imaging algorithms. The images of different types of defect (point reflectors and planar cracks) were used to investigate the robustness of the imaging algorithms. It is shown that, with using CCF, higher image resolution can be achieved, but that the images of cracks are distorted. It is also shown that the detection limit of the imaging algorithms is almost equal for weakly scattering defects.
An accelerometer sensor finite element analysis and design based on fiber Bragg grating
Author(s):
Meng Yang;
Qi Jiang
Show Abstract
A three-axis fiber Bragg grating for the measurement of acceleration is reported. Results obtained using intensity modulation-direct detection (IM-DD)method demonstrate a demodulated signal output range of 1.87Hz~80Hz.Modal analysis and harmonic analysis are performed utilizing finite element analysis method. The strain change is proportional to the acceleration. The sensitivity is 55.3με/g. Low cross-axis sensitivity is obtained. Arrays of such devices can be utilized in a variety of applications such as structural monitoring.
Fiber optic accelerometer based on clamped beam
Author(s):
Wentao Zhang;
Fang Li
Show Abstract
In this paper a fiber optic accelerometer (FOA) based on camped beam is proposed. The clamped beam is used as the elastic element and a mass installed on the clamped beam is used as the inertial element. The accelerometer is based on a fiber optic Michelson interferometer and has a sensing arm and a reference arm. The optical fiber of the sensing arm is wrapped on the clamped beam and the mass, which are both cylinder shaped. The sensitivity of the FOA is analyzed based on the theory of elasticity; the frequency response is analyzed based on the theory of vibration. Experiment is carried out to test the performance of the fiber optic accelerometer. The experiment results show a high sensitivity and a flat frequency response within the low frequency range of 5-250 Hz, which agrees well with the theoretical result.
Designing a warning system of pipeline net based on detecting vibration
Author(s):
Jinhao Sun;
Shangchun Fan;
Guohong Li
Show Abstract
A pipeline network security warning system is designed based on vibration detection techniques, which consist of the front nodes module, relay modules and the computer monitor center in this paper. Someone dig in the ground of pipeline and destruction of the pipeline, when pipe stress change and the acceleration sensor close to the walls of the pipe feel the stress change. The signal through sampling transmit to ARM processor and after Wavelet denoising and the genetic algorithm processing and to have the true and false judgment by the relay modules to the information of the computer monitoring and control center with GSM module, and then PC monitoring software sound and light alarm and forwarding alarm information to the related personnel. At last the experiment shows the system could fulfill the objectives, that is, lower false alarm ratio and higher response ability.
Influence of metal bonding layer on strain transfer performance of FBG
Author(s):
Hao Liu;
Weimin Chen;
Peng Zhang;
Li Liu;
Yuejie Shu;
Jun Wu
Show Abstract
Metal bonding layer seriously affects the strain transfer performance of Fiber Bragg Grating (FBG). Based on the mode of FBG strain transfer, the influence of the length, the thickness, Poisson’s ratio, elasticity modulus of metal bonding layer on the strain transfer coefficient of FBG is analyzed by numerical simulation. FBG is packaged to steel wire using metal bonding technology of FBG. The tensile tests of different bonding lengths and elasticity modulus are carried out. The result shows the strain transfer coefficient of FBGs are 0.9848,0.962 and their average strain sensitivities are 1.076 pm/με,1.099 pm/με when the metal bonding layer is zinc, whose lengths are 15mm, 20mm, respectively. The strain transfer coefficient of FBG packaged by metal bonding layer raises 8.9 percent compared to epoxy glue package. The preliminary experimental results show that the strain transfer coefficient increases with the length of metal bonding layer, decreases with the thickness of metal bonding layer and the influence of Poisson’s ratio can be ignored. The experiment result is general agreement with the analysis and provides guidance for metal package of FBG.
Research of capacitor transimpedance amplifier for infrared readout integrated circuit design with variable integration time
Author(s):
Tai-Ping Sun;
Yi-Chuan Lu;
Hsiu-Li Shieh;
Ming-Sheng Yang;
Tse-Hsin Chen;
Shiang-Feng Tang;
Wen-Jen Lin
Show Abstract
This paper discusses a capacitor transimpedance amplifier (CTIA) designed for an infrared readout circuit. The CTIA has better gain control, high dynamic range, a stability bias point and low impedance. It applies a short-wave detector and small current source because input impedance is very small in an amplifier feedback mechanism. This research on a capacitor transimpedance amplifier (CTIA) is designed for an infrared readout circuit. It is designed, simulated and laid out using the TSMC 0.35um 2P4M CMOS 5V process. The clock rate operates at 3MHz. Layout area is 30umX30um and the array size is 20X16. The simulation current sets 0.01nA~1.3nA. The output swing is 2.8V and power consumption is 10.1 mW according to the measurement results.
Application of Kingview and PLC in friction durability test system
Author(s):
Yinhan Gao;
Jing Cui;
Kaiyu Yang;
Hui Ke;
Bing Song
Show Abstract
Using PLC and Kingview software, a friction durability test system is designed. The overall program, hardware configuration, software structure and monitoring interface are described in detail. PLC ensures the stability of data acquisition, and the KingView software makes the HMI easy to manipulate. The practical application shows that the proposed system is cheap, economical and highly reliable.
Vehicle switch detection system based on Visual C++
Author(s):
Kaiyu Yang;
Bing Song ;
Yinhan Gao;
Junjie Gu;
Ruimin Zhou
Show Abstract
In this paper, the software development of vehicle switch detection systems is explained in detail. The system software is programmed by Visual C++ 6.0 (hereinafter referred to as VC) which is page-friendly and easy for operation. Under the control of the software, the data collection card can collect real-time data through multiple high speed channels. At the same time, the software has date processing function which differentiate the abnormal data and use reasonable and reliable data to replace abnormal data. Finally, the accurate data can be displayed by Teechart control. The accuracy and reliability of the test result are approved by experiments, which meet the requirements of vehicle switch detection.
New gamma - radiation screening procedures of infrared focal plane arrays (IR FPA)
Author(s):
Hong-lei Chen;
Lichao Hao;
Ai-Bo Huang;
Jiamu Lin;
Jun-ling Zhang;
Qi Feng;
Rui-jun Ding
Show Abstract
Infrared focal plane HgCdTe device is used in the environment of complicated astrospace radiation. To achieve the instrument’s actual service life, the anti-radiation ability is needed to study in our research. The irradiation-induced invalidation mechanism of semiconductor materials is introduced in this paper, and the screening experiments' total radiation dose of American Military Standard is also investigated in our study. Through the simulation of astrospace radiation effect by γ -irradiation, the experimental procedures are proved to be rational by the analysis of the experimental data. With the domestic conditions, radiation screening procedures which meets the practical need is suggested.
Two non-contact photoelectric angular position sensors for motion control applications
Author(s):
Tao Xu;
Xiaolu Chen;
Jiang Bo
Show Abstract
The angular position sensor can be integrated into most motion control applications where precision monitoring of angular position is required. In order to eliminate mechanical wear of present angular position sensors for determining the rotation orientation, two new non-contact methods utilizing photoelectric switches are proposed and the corresponding sensors are established. One sensor comprises a gravitational ball, one or more light sources and a circular array of photodetectors, and realizes angular position measurement by setting a block between the light source and the corresponding photodetector which is rotated to the lowest point. Another sensor consists of transmitter-receiver sets and an optical encoder. Different from traditional rotary encoder, the transmitter-receiver sets are arranged around the circumference of rotation, and the optical encoder is only one-turn encoder. The concrete configurations of the sensors are described in detail and typical prototypes are illustrated. Both the angular position sensors are non-contact, compact, and low-cost. They can resist harsh environmental conditions such as vibration, excessive ambient temperature, dirt, moisture and dew, so it is especially well-suited for motion control applications.
Weak feature extraction of gear fault based on stochastic resonance denoising
Author(s):
Jun Zhao;
Xin-huan Lai;
Ming Kong;
Tian-tai Guo
Show Abstract
To solve the problem of feature extraction of weak gear fault under strong noise background, an early feature extraction method based on cascaded monostable stochastic resonance (CMSR) system and empirical mode decomposition (EMD) with teager energy operator demodulation was proposed. The model of monostable stochastic resonance expanded the processing range of characteristic frequency of the measured signal, and had a good effect on denoising performance by cascading. Firstly CMSR was employed as the preprocessor to remove noise, then the denoised signal was decomposed into a series of intrinsic mode functions (IMFs) of different scales by EMD, and finally teager energy operator demodulation was applied to obtain amplitudes and frequencies of each effective IMF to extract the weak gear fault feature. Simulation and application results showed that the proposed method could effectively detect the characteristic frequency of gear fault of local damage after the noise reduction by CMSR.
Capacitive micromachined ultrasonic resonator for ultra sensitive trace gas detection
Author(s):
Li-Feng Ge
Show Abstract
The ultra-sensitive trace gas detection has become increasingly important due to the demand for environment and sci-tech progress. In recent years a capacitive micromachined ultrasonic transducer (CMUT) with circular diaphragms used for imaging has been successfully used to detect chemical gases, and shows promising results. However, its behavior is the same as that of CMUTs for ranging, imaging and therapy applications, where the acoustic radiation with a certain power, produced by the vibration of circular diaphragms operating at the first bending mode, is required but is undesirable for gas sensing since it disturbs inevitably the environment to be measured. This paper, therefore, presents to optimize its behavior after an ideal capacitive micromachined ultrasonic resonator (CMUR) and then to utilize second-order and high-order bending modes of the circular diaphragm to minimize its acoustic radiation and obtain higher resonance frequency also. Since the resonance frequencies of high-order modes much higher than the fundamental frequency, an ultra-high operating frequency of GHz can be reached so that raising greatly the sensitivity of the CMUR and being able to realize the ultra-sensitive trace gas detections.
Compensation for positioning error of industrial robot for flexible vision measuring system
Author(s):
Lei Guo;
Yajun Liang;
Jincheng Song;
Zengyu Sun;
Jigui Zhu
Show Abstract
Positioning error of robot is a main factor of accuracy of flexible coordinate measuring system which consists of universal industrial robot and visual sensor. Present compensation methods for positioning error based on kinematic model of robot have a significant limitation that it isn’t effective in the whole measuring space. A new compensation method for positioning error of robot based on vision measuring technique is presented. One approach is setting global control points in measured field and attaching an orientation camera to vision sensor. Then global control points are measured by orientation camera to calculate the transformation relation from the current position of sensor system to global coordinate system and positioning error of robot is compensated. Another approach is setting control points on vision sensor and two large field cameras behind the sensor. Then the three dimensional coordinates of control points are measured and the pose and position of sensor is calculated real-timely. Experiment result shows the RMS of spatial positioning is 3.422mm by single camera and 0.031mm by dual cameras. Conclusion is arithmetic of single camera method needs to be improved for higher accuracy and accuracy of dual cameras method is applicable.
The novel sliding mode speed control based on interior permanent magnet synchronous motor
Author(s):
Jiaxi Liu;
Lili Li;
Pengcheng Du
Show Abstract
In order to overcome the effect of the nonlinear load and uncertain motor parameters of PMSM in high performance servo system, a high-order terminal sliding mode control method is proposed for the speed loop design. The sliding mode controller is stable with Lyapunov theory and the adaptive of sliding mode gain is obtained. This approach improves the robustness of system and steady response and eliminates the chattering phenomenon. The simulation and experiment system is built to prove the correctness of this method.
Research on state monitoring system using the RS485 bus for hazmat transportation
Author(s):
Xia Zhang;
Jie Fu;
Miao Yu;
Nanqing Zhang;
Weipeng Mei
Show Abstract
In recent years, hazmat transportation’s accidents occur frequently and the road safety transportation issues become increasingly prominent with the demanding for road transport of hazardous goods. However, there are too many types of hazardous goods and every single type has one or several characters. Some of the parameters which are related to security need to be monitored when it comes to transportation. For the tough problem above, this paper presents a sensor data collection technical scheme that is based on the RS485 bus technology. Sensor modules are distributed at various parts of the lorry in order to measure the critical state information of the transporting goods. More importantly, users can get various critical state information they want which corresponds with the transported hazmat by putting different types of sensor modules onto RS485 bus. Combine the above technical scheme with GPS technology and CDMA radio transmission technology, the key state information and location information of the hazmat can be transferred to the supervision and management center to meet the demand of state monitoring.
Active vibration isolation by adaptive proportional control
Author(s):
Yun-Hui Liu;
Wei-Hao Wu;
Chih-Liang Chu
Show Abstract
An active vibration isolation system that applies proportional controller incorporated with an adaptive filter to reduce the transmission of base excitations to a precision instrument is proposed in this work. The absolute vibration velocity signal acquired from an accelerator and being processed through an integrator is input to the controller as a feedback signal, and the controller output signal drives the voice coil actuator to produce a sky-hook damper force. In practice, the phase response of integrator at low frequency such as 2~5 Hz deviate from the 90 degree which is the exact phase difference between the vibration velocity and acceleration. Therefore, an adaptive filter is used to compensate the phase error in this paper. An analysis of this active vibration isolation system is presented, and model predictions are compared to experimental results. The results show that the proposed method significantly reduces transmissibility at resonance without the penalty of increased transmissibility at higher frequencies.
Pressure intelligent control strategy of Waste heat recovery system of converter vapors
Author(s):
Xugang Feng;
Zhiwei Wu;
Jiayan Zhang;
Hong Qian
Show Abstract
The converter gas evaporative cooling system is mainly used for absorbing heat in the high temperature exhaust gas which produced by the oxygen blowing reaction. Vaporization cooling steam pressure control system of converter is a nonlinear, time-varying, lagging behind, close coupling of multivariable control object. This article based on the analysis of converter operation characteristics of evaporation cooling system, of vaporization in a production run of pipe pressure variation and disturbance factors.For the dynamic characteristics of the controlled objects,we have improved the conventional PID control scheme.In Oxygen blowing process, we make intelligent control by using fuzzy-PID cascade control method and adjusting the Lance,that it can realize the optimization of the boiler steam pressure control.By design simulation, results show that the design has a good control not only ensures drum steam pressure in the context of security, enabling efficient conversion of waste heat.And the converter of 1800 flue gas through pipes and cool and dust removal also can be cooled to about 800. Therefore the converter haze evaporative cooling system has achieved to the converter haze temperature decrease effect and enhanced to the coal gas returns-ratio.
Measurement of micro gears with a touch-trigger probe
Author(s):
YenChih Liu;
Kai-Hsiung Chang;
Nia-Chun An;
Sheng-Zhan Yan;
Hsiu-An Tsai
Show Abstract
The measurement of micro gears with a touch-trigger probe will be introduced in this paper. Due to the small size and complex geometry of micro gears, it is difficult to measure them by traditional instruments like coordinate measuring machines (CMM) or laser displacement sensors. This study focuses on this topic and proposes an approach to measure the three dimensional profile of micro gears. The methodology is based on coordinate measurement. A special touch-trigger probe which detects the moment of contact is employed in the measuring system. The diameter of the probe tip is smaller than 2µm and therefore small enough for measuring micro structures. All the calibration and error compensation for the measuring system are discussed in the view of micro metrology. The comparison of measured profiles from both coordinate and image measurement is discussed. Results of experiments show that the proposed approach is worth of further development in the future.
Design of a synchronization control system for lithography based on repetitive control method
Author(s):
Zhongyang Hao;
Guiyong Peng;
Xin Li;
Xinglin Chen
Show Abstract
A repetitive control theory is proposed to solve the synchronization problem between the wafer stage and reticle stage. A macro-micro control method is used based on a macro-micro control structure in which a linear motor is combined with a voice coil motor. A synchronization controller of the reticle stage is added base on the conventional PID control system. The repetitive controller is designed based on the repeated movement of the reticle stage and the wafer stage during the scan and exposure period, and the effects of synchronization control system can be improved because of the repetitive control can effectively track and inhibit the periodicity excitation signal. The repetitive control system effectively reduces the synchronization error during the scan and exposure period，in the meanwhile keep the tracking accuracy and dynamic characters. Simulation results show that the synchronization error can be reduced effectively.
2eVME VME64x slave module design
Author(s):
Wei Du;
Cong Li;
Xinglin Chen;
Yang Liu
Show Abstract
Twenty-one cards access VME64x IPC in the wafer stage control system. So many dedicated boards share one bus lead to increased latency data transmission on the bus. This article uses a low-cost bus upgrade logic module to improve the data transmission capacity of the bus. This module use the 2eVME protocol which VME64x protocol support. The logical interface designed introduced in detail in this paper. Also a simulation experiment is conducted. The simulation results are consistent with the theory. Transferring large amounts of data, the speed of the bus protocol can reach 2 times the ordinary VME protocol speed.
Annular flat-top laser beam generated by an adaptive weight FFT-based iterative algorithm
Author(s):
Dong Wang;
Xiang Liu;
Hao Wang;
Jian Zhang;
Liying Wu
Show Abstract
The generation of a variable diameter annular flat-top laser beam in the far field based on an adaptive weight FFT-based iterative algorithm (AWFFT-IA) and a phase only liquid crystal spatial light modulators (poLCSLM) is demonstrated. The iterative algorithm is used to design the needed phase distribution written on the poLCSLM for the target diameter annular flat-top laser beam shaping. The experimental results show that the method proposed can concentrates about 71% of the incident laser energy into the desired region and the root mean square error (RMSE) of the tailored flat-top intensity profile is more or less 12%.
Approximation of large radio telescope surface with measurement data of optic-electronic stereoscopic system
Author(s):
Konstantin G. Arakantsev;
Igor A. Konyakhin
Show Abstract
The new large radio telescope RT-70 (Uzbekistan, Suffa) requires controlling the linear deformations of its primary mirror. Following issues dealing with this problem are described in this article: 1) the possibility to design measurement system based on stereoscopic scheme for the control of primary mirror’s linear deformations, 2) using the approximation of a parabolic surface by the method of least squares for measurement the coordinates of control elements placed on the primary mirror. It is shown the possibility of assessing the distance to the control points using parameters in equation of a parabolic surface. Information about spatial position of special "stereoscopic" control points is used to calculate the position of all ordinary control points on primary mirror of radio telescope. The results of numerical experiments show that approximation error of paraboloid parameters proporti
Radiation effect of aerodynamically heated optical dome on airborne infrared system
Author(s):
Zhile Wang;
Haosu Xiao;
Zhigang Fan;
Chunxin Qian;
Chengtao Liu
Show Abstract
The temperature of the high speed aircraft optical dome rises rapidly because of aerodynamic heating, which causes severe thermal radiation effect on the detection system in the aerodynamic thermal environment. Therefore, the tracking and acquiring ability of the detector is affected. The temperature distribution of the dome in the aerodynamic thermal environment was investigated through the finite element simulation. The radiative energy factor was used to sample the continuous radiative spectral energy of the dome outside and inside surfaces. The thermal radiation transmission of the dome outside and inside surfaces was simulated numerically using a ray tracing program based on the fourth-order Runge-Kutta algorithm and the Feder method. The number of traced radiative rays of the dome outside and inside surfaces was enormously reduced by introducing the concept of thermal pupil. The irradiance distribution of the dome on the detector’s photosensitive surface was obtained using this ray tracing program. The results showed that the thermal radiation of the dome causes radiation interference for the detection system, and makes the background noise of detection system increase in the aerodynamic thermal environment. Therefore, the thermal radiation of the dome in the aerodynamic thermal environment cannot be neglected.
Frequency stability of the 760 nm DFB laser diodes for laser metrology
Author(s):
Bretislav Mikel;
Zdeněk Buchta;
Josef Lazar;
Ondřej Číp
Show Abstract
At present time the DFB (Distributed FeedBack), laser diodes are the most suitable laser sources from semiconductor laser sources for using in laser interferometry. The DFB laser diodes have narrow frequency linewidth, mode hop free tuning range up to 2 nm and sufficient optical power. In addition to the other types of laser diodes are available in the package with optical fiber at the output and the DFB laser diodes with 1541 nm wavelength has optical isolator inside. Unfortunately the DFB laser diodes with 760 nm wavelength have no optical isolator inside package. This induces a back reflection from the fiber connections at the output to the laser chip. Than the mode hop free tuning range is decreasing rapidly. We present our experience with adaptation of the DFB laser diodes to laser interferometer and methods to decrease back reflection.
We used frequency stabilization by frequency lock to F-P (Fabry – Perot) resonator for VCSEL laser diode but the DFB laser diodes can be better frequency stabilized using absorption to absorption spectrum of gases (760 nm, 1542 nm, 1552 nm) to compare achieved frequency stability of the 760 nm DFB laser diodes.
Analysis and extraction of misalignment errors in a three-in-one composite wave-plate with an equivalent fast axis
Author(s):
Honggang Gu;
Shiyuan Liu;
Xiuguo Chen;
Chuanwei Zhang
Show Abstract
Misalignment errors of the composite wave-plate, a typical kind of compensator used in spectroscopic ellipsometers (SE), can lead to spurious oscillations in the SE measurement. In this paper, we construct an equivalent model of the three-inone composite wave-plate through mathematical derivation, and propose a method to analyze and extract the misalignment errors of the composite wave-plate. Obvious oscillations have been observed in the equivalent fast axis azimuth of the composite wave-plate through simulations, and these oscillations can be assigned to the angular misalignment errors between the individual plates of the composite wave-plate. The waveforms and amplitudes of the oscillations in the equivalent fast axis azimuth show high sensitivity to angular misalignment errors. Conversely, angular misalignment errors can be accurately extracted from the oscillations in the equivalent fast axis of the composite wave-plate. It is expected that the proposed method for analysis and extraction of misalignment errors can be used to minimize angular misalignment errors and to improve the alignment procedure of the composite wave-plate.
Terahertz resonant transmission based on annular aperture arrays
Author(s):
Yan Zhang;
Dan Hu
Show Abstract
We investigate extraordinary terahertz transmission through the H-shaped annular aperture arrays (AAAs) drilled in a thin metal film on a doubly polished p-type silicon wafer by use of the traditional terahertz time domain spectroscopy (THz-TDS). A surprising result is that only odd order resonant modes are observed for the symmetrical structures, but both odd and even order resonant modes can be displayed for the asymmetrical structures. Breaking the symmetry of the H-shaped AAAs by gradual displacing the H-shaped AAAs to the U-shaped AAAs allows an intensity modulation depth of 98.7% of the second order resonance. All the resonant frequencies are insensitive to the details of the shape for the H-shaped annular aperture, but mainly depend on the total circumference in a unit cell. Furthermore, a clear inverse proportion relationship between the resonant frequencies and the total circumference is revealed and confirmed experimentally and numerically. The experimental conclusions are verified by the simulation results well. These characteristics pave an avenue to the quick and accurate construction of the desired operating frequencies for filtering, bio-sensing, optical modulation, and ultrafast switching applications.
Optic-electronic systems for measurement the three-dimension angular deformation of axles at the millimeter wave range radiotelescope
Author(s):
Igor A. Konyakhin;
Tatyana V. Kopylova;
Alexsey I. Konyakhin;
Andrey A. Smekhov
Show Abstract
Researches in the millimetre wave range require the high accuracy for position of the mirror components of the radiotelescope. A mirror weight is the cause of the three-dimension angular deformation of the elevation axle and azimuth axle relatively bearings. At result the elevation angle and azimuth angle of a parabolic mirror axis orientation is not equal to the set values. For the measuring roll, pitch and yaw angular deformations the autocollimation system with new type of the reflector are used. Reflector for autocollimation measurements as compositions of the anamorphic prism and special tetrahedral reflector is described. New methods for roll, pitch, yaw angles measuring are discussed. Optical scheme for the measurement system, structure the anamorphic prism and tetrahedral reflector are proposed. Equations for the static characteristic of the measuring system are shown.
Survey of illuminance distribution of vignetted image at autocollimation systems by computer simulation
Author(s):
Igor A. Konyakhin;
Andrey Smekhov
Show Abstract
During installation and maintaining industrial large-scale structures there is a necessary of usage angular measuring devices such as autocollimation systems, which allows controlling some characteristics of objects. Moreover, autocollimation systems are often used in science experiments and technical modeling. Parallelism, coaxiality, other alignments, yaw, roll, pitch or deformation angles are the wide spread parameters often required to be determined. However, autocollimation systems have some principal issues. Errors caused by incoming radiation vignetting is one of them. Despite the resulting image at the detector’s sensitive area is reduced by entrance aperture, the errors of such vignetting could be eliminated being systematical ones. Implementation of the software model, which traces rays through the simulated autocollimation system, predicts the illuminance distribution and calculates vignetting errors are the purposes of this survey. The amount of precalculated vignetting errors for each reflecting element position which is fixed at the object to control is saved at any database. Due to the simple recovery algorithm this amount gives the possibility to reconstruct the real object position and eliminate vignetting error. Furthermore, the ability to model different types of apertures, reflecting elements and emitter’s radiation patterns incorporated into the software gives the ability to apply one at much more complicated systems and decrease the time and exps of a design process.
A method of constructing motion-blurred image based on weighted accumulation of subimages
Author(s):
Yanqiao Zhao;
Jian Liu;
Jiubin Tan;
He Zhang
Show Abstract
A new approach of degrading image is presented. This method has four steps: obtain the number of the subimages first, and then these subimages are constructed, the third step is calculating the weight of each subimage according to its velocity, at last motion-blurred image is constructed by weighted accumulating the subimages. We compared the effects between the method of this article and existing algorithms by using accelerated motion-blurred images and retrace motion-blurred images separately. The maximum absolute differences between the accelerated motion-blurred images degraded by the method of this article and the existing algorithms which are discrete convolution (DC) and discrete Fourier transform (DFT) are 2.5580×10-13 and 3.4106×10-13 separately. And the maximum absolute differences are 2.5580×10-13 and 3.4106×10-13 separately for retrace motion-blurred images. It can be proved that the performances of different methods are the same. The time consumed by degrading images of different forms of motion is less than half a second, close to the time consumed by DFT, but hundreds of seconds shorter than DC. What’s more, the process of the method of this article strongly resembles the real imaging process, so it can be comprehended more easily than the existing algorithms.
Design and adjustment of a near-IR camera system
Author(s):
Tingyu Liu;
Jingxu Zhang;
Yapeng Li
Show Abstract
In order to achieve a large field of view for a 1.23m large telescope, the design and assembly of a near-IR telescope has been done in this paper. First, an on-axis reflected system was designed based on the optical theory. Secondly, by designing and analyzing the deformation of different support structures for the secondary mirror and the deformation of cylinder type and truss structure, the three-beam secondary mirror support structure and the truss structure were chosen. Last, the adjustment was done by a proper secondary mirror adjusting device and a proper CCD counter-rail. A test was done after the assembly and adjustment, with the result of RMS=0.10618 λ, PV=0.55362 λ（λ=632nm）. It is proved that the design of the near-IR system can satisfy the requirements of the optical design and imaging according to the test result.
Design of infrared polarizer based on sub-wavelength metal wire grid
Author(s):
Wenrui Guo;
Zhiwei Li;
Hongtao Gao;
Liangping Xia;
Lifang Shi;
Qiling Deng;
Chunlei Du
Show Abstract
High performance infrared polarizer with broad band is required for various infrared applications. The conventional infrared polarizer, based on the birefringence effect of natural crystal, is cost-consuming in fabrication and can hardly be integrated into micro-optical systems due to its large bulk. In this paper, an infrared polarizer is proposed in the spectrum from 3 to 19 μm based on sub-wavelength metal wire grid. The dependence of the performance on some key parameters, including metal materials, geometrical parameters, has been deeply investigated by using the Finite-Difference Time-Domain (FDTD) method. The results show that Au wire-grids have a higher transmittance for the Transverse Magnetic（TM） mode light than that of other metal materials, and both the grid period and the grid thickness have important impact on the performance. Based on these observations, a polarizer has been designed by choosing the optimal value of related parameters. Numerical simulation suggests that the designed infrared wire grid polarizer have advantages of broad band, high TM polarization transmission efficiencies and high extinction ratios. The transmission efficiencies of TM polarization are larger than 59.3%, and the extinction ratios range from 28.6 to 44.6 dB in that range of the spectrum.
Micro-hole fabrication based on focus-shaped radially polarized beams
Author(s):
Furong Du;
Zhehai Zhou;
Xiaoqing Zhang;
Lianqing Zhu
Show Abstract
A micro-hole fabrication scheme based on focus-shaped radially polarized beams is presented. First, a micro-hole fabrication system is demonstrated based on the focus shaping of radially polarized beams, where a high energy ultra-small spot with a long depth of focus can be obtained by focus shaping using the combination of a diffractive optical element (DOE) and a high numerical-aperture objective, and such focused spot is preferred to fabricate the micro-hole with a high ratio of depth and radius. Then, diffractive optical elements (DOEs) are designed to achieve such ultra-small spots with a long depth of focus using the global search algorithm, and the focus-shaped field intensities are calculated based on vector diffraction theory. Finally, a conclusion is drawn from the theoretical analysis and numerical simulation, and focus-shaped radially polarized beams are suitable to fabricate the micro-hole with a high ratio of depth and radius.
Development of a three dimensional scanning touch probe with high precision and low contact force
Author(s):
Chih-Liang Chu;
Jhih-Sian Ke;
Hung-Chi Chen
Show Abstract
This study aims to develop a three dimensional scanning touch probe with high precision and low contact force. The overall design has two parts, mechanism design and optical path design. The mechanism design contains three parts, Zaxis system, XY-axis system, and probe mechanism. The Z-axis system applies the characteristic of the thin sheet spring to move vertically. In the design of XY-axis system, a micro-beam is employed, through which length, width, thickness of the micro-beam and corresponding dimensions of the leaf spring are designed according to the selected contact force. The freedom degree is limited to three. And the center of the mechanism is equipped with a stylus to inhibit displacement of the Z-axis. The contact between the probe and the workpiece only leads to change in the angles of Xand Y-axes, achieving the feature of 2-degree freedom. To enable rapid change for the probes, this study designs a probe mechanism, reliability of which is analyzed and validated with ANSYS software, so that the design of 3-degree freedom mechanism is completed. The sensor has a laser diode to coordinate with Position Sensor Detector (PSD) which works with the optical path designed to measure placement of Z-axis and angle placement of XY-axis. By validation through an experiment, the three dimensional scanning touch probe developed by this study has a measuring range of ±1mm×±1mm×1mm, and unidirectional repeatability of 0.6um.
Heterodyne planar grating encoder with high alignment tolerance, especially insensitivity to grating tilts
Author(s):
Can Feng;
Lijiang Zeng;
Shiwei Wang
Show Abstract
Planar grating encoder, composed of one two-dimensional grating and the optical system (grating interferometer), is able
to measure two-dimensional displacements. Grating interferometer errors are the errors caused by grating tilts, which
possibly make phase changes of optical paths, and interfering beams non-parallelism. A new design of planar grating
encoder based on optical heterodyne interferometry with a symmetric setup and double diffraction is proposed. It can
measure the planar displacement with high resolution and high stability. With help of retro-reflectors, the tilts of the
grating do not change the interference pattern and bring no measurement errors theoretically. The planar grating encoder
has been set up, and the measurement results are compared with a two-axis laser interferometer. The repeatability of the
grating encoder is about 10nm, and the laser interferometer comparing results confirm its error insensitivity to grating
tilts.
Recent developments in heterodyne laser interferometry at Harbin Institute of Technology
Author(s):
P. C. Hu;
J. B. Tan;
H. X. X. Yang;
H. J. J. Fu;
Q. Wang
Show Abstract
In order to fulfill the requirements for high-resolution and high-precision heterodyne interferometric technologies and instruments, the laser interferometry group of HIT has developed some novel techniques for high-resolution and high-precision heterodyne interferometers, such as high accuracy laser frequency stabilization, dynamic sub-nanometer resolution phase interpolation and dynamic nonlinearity measurement. Based on a novel lock point correction method and an asymmetric thermal structure, the frequency stabilized laser achieves a long term stability of 1.2×10-8, and it can be steadily stabilized even in the air flowing up to 1 m/s. In order to achieve dynamic sub-nanometer resolution of laser heterodyne interferometers, a novel phase interpolation method based on digital delay line is proposed. Experimental results show that, the proposed 0.62 nm, phase interpolator built with a 64 multiple PLL and an 8-tap digital delay line achieves a static accuracy better than 0.31nm and a dynamic accuracy better than 0.62 nm over the velocity ranging from -2 m/s to 2 m/s. Meanwhile, an accuracy beam polarization measuring setup is proposed to check and ensure the light’s polarization state of the dual frequency laser head, and a dynamic optical nonlinearity measuring setup is built to measure the optical nonlinearity of the heterodyne system accurately and quickly. Analysis and experimental results show that, the beam polarization measuring setup can achieve an accuracy of 0.03° in ellipticity angles and an accuracy of 0.04° in the non-orthogonality angle respectively, and the optical nonlinearity measuring setup can achieve an accuracy of 0.13°.
A method for long absolute distance measurement based on high stability and synchronous multi-frequency
Author(s):
Hongxing Yang;
Zhigang Fan;
Yu-wei Ma
Show Abstract
In order to improve the measurement accuracy and the real-time performance in long absolute distance measurement, a method based on high stability and synchronization multi-frequency is proposed. Multi-frequency is generated by shifting one mode laser frequency with three acousto-optic frequency shifters, and couple in one beam by fiber. Heterodyne frequencies between different multi-frequency is separated by its different polarization and frequency bandwidth, and acted as the coarse and precision measuring frequency. Therefore synchronous occurrence of measuring multi-frequency is achieved, which improve the real-time performance of measurement. Results of the experiment show that the measuring frequency stability is better than 3.6×10-8, and the laser range finder have an uncertain measuring result of less than 60 μm at a distance of 20 m under laboratory conditions.
Observations of the boundary layer structure, cloud and aerosol properties with portable Mie scattering lidar
Author(s):
Qing Yan;
Dengxin Hua;
Shichun Li;
Yufeng Wang;
Zhirong Zhou
Show Abstract
A portable Micro-pulsed Mie scattering lidar at the laser wavelength of 532 nm has been developed for routine observation of atmospheric optical properties of the lower troposphere, including boundary layer structure, cloud, the distribution of aerosol and horizontal visibility and so on. The configuration of lidar and its design methods including the hardware and software were described in details. The lidar system was controlled by compact computer, including self adjustment for coaxial lidar, three-dimensional scanning, real-time data processing of visualization and inversion online. The experimental results illustrate that the system can measure the atmospheric aerosols up to the range of near 5 km at daytime and up to 15 km at nighttime under the measurement conditions of laser energy of 50 μJ, signal averaging time of 40s, a receiving aperture 254 mm, range resolution of 7.5 m and analog detection model, which can provide scientific measurement data for studying the atmospheric environment change, particularly for resolving the particulate pollutant generation, transmission and diffusion characteristics.
Dual-axes tri-differential confocal sensing technique with higher axial resolution and SNR
Author(s):
Chao Liu;
Lirong Qiu;
Qin Jiang;
Weiqian Zhao
Show Abstract
The axial response curve of dual-axes confocal microscopy (DCM) has a shift while the point detector has a transverse offset from the optical axis. Based on this, a dual-axes tri-differential confocal sensing technique (DTCST) with absolute zero and high axial resolution is proposed. DTCST sets three micro-regions as virtual pinholes on DCM detecting plane to achieve the Airy spot division detection, which one micro-region is set at the focus and two micro-regions are set symmetrically about the focus along determined direction. DTCST uses a CCD as detector and adjusts the size and position of pinholes freely in software, can significantly simplify detection system and can eliminate the errors attributed to the dissymmetrical placement of pinholes and property difference of the detectors. DTCST uses the pairwise differential subtraction of three intensity responses detected simultaneously from the three micro-regions to achieve high resolution absolute measurement and low noise. Theoretical analyses and preliminary experiments indicate that DTCST has an improved axial resolution, an extended measurement range, as well as strong anti-interference capability and sectioning detection capability.
High speed 3D surface inspection with digital holography
Author(s):
Andreas Brunn;
Nicolas Aspert;
Etienne Cuche;
Yves Emery;
Andreas Ettemeyer
Show Abstract
Digital holography has proven its ability to acquire high accuracy full field 3D data with one single image acquisition. This means that in principle this technique offers the chance to perform 3D serial inspection processes, as well. However, one limitation in digital holography is its limited ability to measure rough surfaces. In the presence of rough surfaces, the magnification of the image has to be increased to capture the required phase information on each camera pixel. However, this leads to significant reduction of inspection speed. If low magnification is selected, the rough surface produces speckles which cannot be treated properly by digital holography algorithms. In this paper, we describe the extension of digital holography to rough surface applications using speckle interferometry technique. This technique is capable of fast inspection of rough surfaces with sub-micrometer accuracy. The principle of this approach is shown and a practical application for 3D surface inspection of wafer cutting processes is given.
Near infrared tunable diode laser absorption spectroscopy for ethylene concentration analysis
Author(s):
W. D. Pan;
J. M. Dai;
Y. F. Zhang;
L. Zhang
Show Abstract
The absorption spectra of ethylene (C2H4) located at v5+v9 band near 1626nm involve some strong peaks that are suitable for trace gas concentration detection. They are interference free from other abundant molecules that are normally present in the atmosphere. An ethylene analysis system has been developed based on the tunable diode laser absorption spectroscopy. The high resolution transmission of ethylene near 1626nm has been measured by this system under different concentration. The severe overlapping between neighboring spectral lines of ethylene is observed and they cannot be separated with each other easily under atmospheric pressure and room temperature, so a multi-peaks spectrum recognition method is proposed to separate the ethylene spectrum from other interference gas while the ethylene concentration is ultra low. A mixture of high concentration methane, low concentration ethylene with air is used to evaluate the recognition efficiency. The result shows that the ethylene line can be abstract from strong background interference using multi-peaks spectrum recognition method and the accuracy of concentration measurement can reach about 5% comparing with a mass flow meter.
Evaluation of Spatial Straightness Error using LaserTRACER
Author(s):
Mingzhao He;
Xiaoyou Ye;
Jianshuang Li;
Xiaochuan Gan
Show Abstract
In order to improve the evaluation precision of spatial straightness error, new measurement setup using 4 LaserTRACERs were built at National Institute of Metrology (NIM). The LaserTRACER is a length measurement device with sub-micron accuracy. In principle, the LaserTRACER is a traceable interferometer. Experiment was implemented on a granite rail with air-suspending slider to test the spatial straightness of the rail. In the experiment, the retroreflector was mounted on slider and moves alone the rail after the spatial frame of axes was built. Using 4 LaserTRACERs, the spatial coordinates can be calculated by Multilateration algorithm. The optimal arrangement of LaserTRACERs is studied by simulation and experiment. The mathematical model based on GBT11336-2004 was built, and Least squares method is used in the spatial line fitting. The measurement principle and results were verified by comparison with SpatialAnalyzer and Metrolog XG.
Reduce impact of the Talbot effect in laser parallel confocal measurement within LED
Author(s):
Qing Yu;
Ruifang Ye;
Wei Fan
Show Abstract
The axial resolution of parallel confocal measurement can be improved as the laser source added into the system, but extreme monochromaticity of laser beam will produce the Talbot effect, which is an effect of many images of point light array appear along the optical path direction, and it causes to distinguish the true in-focus image from lots of Talbot images difficultly, which means the confocal measurement can’t be carried on. The author researched factors of the influences for Talbot distance, and developed some methods to weaken the impact of the Talbot effect. A LED was added into the laser parallel confocal measurement system to find the in-focus image, and there were no Talbot images nearby to impede positioning, and then the laser beam was lead into the system to measure with high precision. The difference of location of the two in-focus images with laser and LED was about 11μm in the experiment, which was shorter than one Talbot distance in the system, and the result indicated that the in-focal could be distinguished with this method.
High-precision gasket thickness measuring and classifying system based on line-structured light
Author(s):
Qinghua Wu;
Tao He;
Tielin Shi
Show Abstract
In this paper, a high-precision flat gasket thickness measuring and classifying system based on line-structured light is presented. The system consists of a part feeding device, a measurement platform, a measurement and control subsystem and a classifying subsystem. The measurement system is based on the optical trigonometry measurement principle. Different from other common measurement system, a line-structured light instead of a beam is projected to the surface of the measured object. From a stripe the measured result will get more confirmation than a single beam spot. More than one frame of image are grabbed and averaged to reduce the random error. The gravity center algorithm is used to extract the center-point of the stripe in one column. According to the least squares method, a straight line can be fitted from gravity center-points extracted. A virtual grate is designed to improve the resolution of the measurement system. The calibration of the measurement system is designed and realized. An experiment is built and the measurement result is analyzed. The result shows that the uncertainty of the measurement system is limited in ± 0.003mm. And this system can be used for classifying the gaskets by thickness.
Comparison of fringe imaging techniques using Mach-Zehnder and Fabry-Perot interferometer for molecular Doppler wind lidar
Author(s):
Linqiu Tan;
Dengxin Hua;
Li Wang;
Yufeng Wang
Show Abstract
The fringe-imaging Fabry-Perot (FIFP) interferometer and fringe-imaging Mach-Zehnder (FIMZ) interferometer as frequency discriminator for incoherent molecular Doppler wind lidar are proposed, analyzed and compared theoretically respectively. Using ZEMAX software, the FIFP interferometer and FIMZ interferometer are designed and simulated respectively. Compared with Fabry-Perot interferometer (FPI), Mach-Zehnder interferometer (MZI) produces equidistant linear parallel fringes instead of circular rings. The record of the MZI fringe pattern is noticeably easier than that of the FPI and can be performed with a cylindrical lens and focused on a linear CCD array rather than a complex circle to line interferometer optical (CLIO) system. According to the U.S. standard atmospheric model, the transmission, signal-to-noise ratio (SNR), sensitivity and wind error for FIFP and FIMZ systems are simulated respectively. The results show that, the MZI sensitivity is lower than that of FPI, however, the MZI offers 4 times higher transmission, resulting to about 1.4 times smaller wind error in the line-of-sight (LOS) velocity component than that of FIFP. In addition, the MZI can be designed with a compensated field to accept sources of appreciable dimensions without significant performance reduction, which will provide an effective technique for Doppler wind lidar to improve the accuracy of wind velocity measurement by using MZI as frequency discriminator.
Design of an optical ultrasonic signal testing system using LabVIEW
Author(s):
Yukun Luo;
Shitu Luo;
Feilu Luo;
Mengchun Pan;
Xianglin Tan
Show Abstract
Optical methods are used in ultrasonic testing to overcome the limitation of conventional contact transducers in bad situations and have become a hot branch in ultrasonic testing methods. However, the sensitivity in optical methods is lower than that of contact transducers and the use of laser devices brings more noises, which make the signal to be tested more complex. In view of the characteristics of the signal in optical testing, wavelet transform and complex analytic wavelet envelope detection are introduced to extract the signal and its features. Then an optical ultrasonic signal testing virtual instrument system based on LabVIEW is designed, integrating signal acquisition, digital filtering, noise suppression, power spectrum analysis, peak extraction and envelope detection as a whole. Compared with those heavy and expensive equipments, the friendly interface, convenient operation and high extendibility prove its flexibility and value. Finally, experiments are carried out to verify the reliability and precision of the system. Results show a relatively error below 1% in multiple measures.
Diode lasers for interferometric length measurements
Author(s):
Ahmed Abou-Zeid
Show Abstract
An overview is given on investigation activities of author’s researcher groups at the PTB, the National Metrology Institute of Germany, for testing, developing and applying of diode lasers to be used as a light source in interferometry. After a short background about laser emission’s principle and types of diode lasers their spectral properties are described in detail with taking their using in interferometry into account. Then different methods of frequency stabilization of diode lasers are briefly discussed. Lastly several examples for application of diode laser interferometers for length measurements are reported.
Generation of cylindrical vector beams with a cat-eye cavity laser and a Mach-Zehnder interferometric arrangement
Author(s):
Baoling Xiao;
Zhaohui Hu;
Zhehai Zhou;
Shulian Zhang;
Jie Yang;
Xiaoling Wang;
Lianqing Zhu
Show Abstract
A novel method to generate cylindrical vector beams is presented based on a cat-eye cavity laser and a Mach-Zehnder interferometric arrangement. Some transverse modes can be generated by the cat- eye cavity laser and then superimposed by the Mach-Zehnder interferometric arrangement to form different kinds of cylindrical vector beams. First, simulations of four kinds of cylindrical vector beams based on four kinds of combinations of transverse modes are made and other situations are also discussed when the two beams are in-phase, 180° out-of-phase and with other phase difference. Then, an experimental set-up based on a cat-eye cavity laser and a Mach-Zehnder interferometric arrangement is built, and four forms of cylindrical vector beams generated by the experiment system. The experimental results agree well with the simulative results.
Research and development of the laser tracker measurement system
Author(s):
Z. L. Zhang;
W. H. Zhou;
D. B. Lao;
J. Yuan;
D. F. F. Dong;
R. Y. Y. Ji
Show Abstract
The working principle and system design of the laser tracker measurement system are introduced, as well as the key technologies and solutions in the implementation of the system. The design and implementation of the hardware and configuration of the software are mainly researched. The components of the hardware include distance measuring unit, angle measuring unit, tracking and servo control unit and electronic control unit. The distance measuring devices include the relative distance measuring device (IFM) and the absolute distance measuring device (ADM). The main component of the angle measuring device, the precision rotating stage, is mainly comprised of the precision axis and the encoders which are both set in the tracking head. The data processing unit, tracking and control unit and power supply unit are all set in the control box. The software module is comprised of the communication module, calibration and error compensation module, data analysis module, database management module, 3D display module and the man-machine interface module. The prototype of the laser tracker system has been accomplished and experiments have been carried out to verify the proposed strategies of the hardware and software modules. The experiments showed that the IFM distance measuring error is within 0.15mm, the ADM distance measuring error is within 3.5mm and the angle measuring error is within 3〞which demonstrates that the preliminary prototype can realize fundamental measurement tasks.
Experimental validation of non-sphericity effect on monochromatic rainbow measurement
Author(s):
Qi Pan;
Zijia Zhang
Show Abstract
Monochromatic rainbow measurement, as a laser based interference detecting technique, is always used to measure particle refractive index. However, the accuracy of this method is effected by particle non-sphericity. In this paper, the non-sphericity effect is analyzed from both simulation and experiment. The non-sphericity effect for both prolate and oblate spheroid is studied. The simulation result shows that the axial ratio greatly effects the rainbow angle position, and eventually effect the refractive index evaluation. An experiment is also taken. The refractive indexes of ethanol solutions with different concentration are measured by monochromatic rainbow method. A comparison is taken between the results measured from the rainbows formed by a liquid cylinder and rainbows of free falling droplets.
Design of digital Pound-Drever-Hall frequency stabilizing system for two-cavity dual-frequency Nd:YAG laser
Author(s):
Junhong Xing;
Mingxing Jiao;
Yi Zheng;
Lingling Zheng
Show Abstract
Two-cavity dual-frequency Nd:YAG laser with large frequency difference can be used as an ideal light source for synthetic-wave absolute-distance interferometric system. The operation principle of the two-cavity dual-frequency Nd:YAG laser with large frequency difference has been introduced, and the frequency locking principle of the Pound-Drever-Hall (PDH) method has been analyzed. A FPGA-based digital PDH frequency stabilizing system for the two-cavity dual-frequency Nd:YAG laser has been designed, in which the same frequency reference of a high finesse Fabry-Perot cavity is used and two separate heterodyne interference sub-systems are employed so that two electrical error signals can be obtained. Having been processed through FPGA, the output signals are applied to drive the PZT frequency actuators attached on the two-cavity dual-frequency Nd:YAG laser, as a result both operating frequencies of the two-cavity dual-frequency Nd:YAG laser can be simultaneously frequency-locked to two resonant frequencies of the Fabry-Perot cavity. A frequency stability of better than 10-10 will be obtained by use of the digital PDH frequency locking system, which can meet the needs of synthetic-wave absolute-distance interferometry.
Frequency stabilization of internal-mirror He-Ne lasers by air cooling
Author(s):
Jin Qian;
Zhongyou Liu;
Chunying Shi;
Xiuying Liu;
Jianbo Wang;
Cong Yin;
Shan Cai
Show Abstract
Instead of traditional heating method, the cavity length of an internal-mirror He-Ne laser is controlled by air cooling which is generated by a mini cooling fan. A PID servo controlling system is designed to drive the cooling fan tuning the frequency of the laser. The frequency is stabilized by balancing the power of two operating longitudinal modes. Beating with an iodine stabilized He-Ne laser, a relative uncertainty(Δf / ̅f ) of 4.3×10-9 in 5 months, a frequency fluctuation of less than 2.6 MHz and an Allan deviation of 3×10-11 (τ=100 s) in 75 h are obtained.
Transformation mechanism of nonlinearity harmonics caused by laser polarization in the heterodyne laser interferometer
Author(s):
Haijin Fu;
Jiubin Tan;
Pengcheng Hu;
Zhigang Fan
Show Abstract
The improvement of the heterodyne laser interferometer accuracy is strongly restricted by the periodic nonlinearities which arise from the optical mixing in the measurement and reference arms. Imperfect laser polarization is a principal factor leads to the optical mixing, which can cause the first- or second-order nonlinearities, or both of them, but the transformation mechanism of the two nonlinearities is still ambiguous. Starting from the nonlinearity model based on optical mixing, this paper derives the nonlinearity expression with the two-frequency laser polarization parameters, which is applied to analyze the transformation mechanism of the nonlinearity harmonics. Simulation results shows that the coincident degree with the orthogonality of Jones vectors of the two laser components determines the existence condition of the first- and second-order nonlinearities, i.e. when the orthogonality is satisfied, the error caused by laser polarization is the second-order nonlinearity; when the orthogonality is far dissatisfied, the error caused by laser polarization is almost the first-order nonlinearity, whose magnitude is generally one order larger than that of the second-order nonlinearity; beside the above-mentioned two conditions, the error caused by laser polarization is composed of the first- and second-order nonlinearities.
Universal characterization method for 3D tactile probing systems
Author(s):
Nelson Ferreira;
Thomas Krah;
Karin Kniel;
Stephanus Büttgenbach;
Frank Härtig
Show Abstract
The method of characterizing three-dimensional tactile probing systems is significant when it comes to determining the
accuracy of measurements on coordinate measuring machines. The universal characterization method presented in this
paper aims at a mathematical description of the probing behavior of three-dimensional tactile systems. In this way, the
model developed is able to help improve the accuracy by properly determining 13 probe parameters. These parameters
comprise 9 stiffness values for the probing system laid out in a 3x3 matrix, 3 position vector parameters from the stylus
sphere as well as its diameter. These values can be used to compensate linear elastic distortion, which is due to the
stiffness of the measurement system, the stiffness of the stylus shaft and the mechanical flattening of the calibrated
sphere and the stylus sphere. The presented characterization method can be applied to various types of styli, ranging
from macro sizes to micro sizes. An exemplary system based on a silicon micro probing system will be described. It is
applied in coordinate metrology for the measurement of outer and inner surfaces of micro structures.
Particle filtering for sensor-to-sensor self-calibration and motion estimation
Author(s):
Yafei Yang;
Jianguo Li
Show Abstract
This paper addresses the problem of calibrating the six degrees-of-freedom rigid body transform between a camera and an inertial measurement unit (IMU) while at the same time estimating the 3D motion of a vehicle. A high-fidelity measurement model for the camera and IMU are derived and the estimation algorithm are implemented within the particle filter (PF) framework. Belonging to the class of Monte Carlo sequential methods, the filter uses the unscented Kalman filter (UKF) to generate importance proposal distribution. It can not only avoid the limitation of the UKF which can only apply to Gaussian distribution, but also avoid the limitation of the standard PF which can not include the new measurements. Moreover, the proposed algorithm requires no additional hardware equipment. Simulation results illustrate the ill effects of misalignment on motion estimation and demonstrate accurate estimation of both the calibration parameters and the state of the vehicle.
Calibration of magnetic gradient tensor measurement array in magnetic anomaly detection
Author(s):
Jinfei Chen;
Qi Zhang;
Mengchun Pan;
Feibing Weng;
Dixiang Chen;
Hongfeng Pang
Show Abstract
Magnetic anomaly detection based on magnetic gradient tensor has become more and more important in civil and military applications. Compared with methods based on magnetic total field or components measurement, magnetic gradient tensor has some unique advantages. Usually, a magnetic gradient tensor measurement array is constituted by four three-axis magnetometers. The prominent problem of magnetic gradient tensor measurement array is the misalignment of sensors. In order to measure the magnetic gradient tensor accurately, it is quite essential to calibrate the measurement array. The calibration method, which is proposed in this paper, is divided into two steps. In the first step, each sensor of the measurement array should be calibrated, whose error is mainly caused by constant biases, scale factor deviations and nonorthogonality of sensor axes. The error of measurement array is mainly caused by the misalignment of sensors, so that triplets’ deviation in sensors array coordinates is calibrated in the second step. In order to verify the effectiveness of the proposed method, simulation was taken and the result shows that the proposed method improves the measurement accuracy of magnetic gradient tensor greatly.
Research on self-calibration method for tri-axial magnetic compass
Author(s):
Zhi Li;
Xiang Li
Show Abstract
A novel method for the self-calibration of a tri-axial magnetic compass is discussed in this paper. Firstly, the conventional calibration method of tri-axial magnetometer in compass based on ellipsoid fitting is theoretically analyzed, and its weakness is demonstrated. Secondly, an improved calibration scheme for both the magnetometer and accelerometer in a tri-axial magnetic compass is proposed, which utilize the invariance of the dot product of two constant vectors and can overcome the disadvantages of the ellipsoid fitting method. The proposed method is verified by numerical simulation and experiment, and the results prove its superiority over the conventional algorithm of ellipsoid fitting.
Robust CMOS camera module lens calibration by support vector machine regression
Author(s):
Chan-Yun Yang;
Gene Eu Jan;
Yung-Yuan Chen
Show Abstract
Motivated by the powerful computational capability in the emerging hardware, an applicable paradigm with its embedded lens calibrator is proposed. The proposed new paradigm for the relationship between the image provider and the image processor shows both the functional and economical merits. The paper first focuses on the developed of the embedded lens calibrator. An underlying support vector machine base regression (SVR) is hence employed as the key to achieve the goal. Based on the structural risk minimization, the SVR, employed as the calibration regressor, simultaneously minimize both the model complexity and empirical error, and create an estimator with a wide margin. The wide margin in regression represents a smooth approximation function for the lens calibration in which variances commonly existed in the CMOS camera modules can tolerably be eliminated. The variance tolerability achieves the calibration function a high robustness, and would conduct potentially the success of the proposed paradigm.
Error analysis and method of calibration for linear time grating displacement sensor
Author(s):
Zhonghua Gao;
Fangyan Zheng;
Xihou Chen;
Ziran Chen;
Donglin Peng
Show Abstract
A combination method for calibrating the errors of linear time grating displacement sensor is presented. Based on further analysis of time grating, periodic errors, Abbe errors and thermal expansion errors are integrated to obtain error curve for setting up error model, which is adopted to compensate errors using Fourier harmonic analysis and the principle of liner expansion, respectively. Results prove that this method solves the difficult issues about error separation in the linear measurement, and significantly improves the accuracy of linear time grating. Furthermore, this method also solves the issues about continuous automatic sampling with computer, so that the calibration efficiency has been greatly enhanced.
Multi-wavelength emissivity measurement of stainless steel substrate
Author(s):
Y. F. Zhang;
J. M. Dai;
L. Zhang;
W. D. Pan
Show Abstract
The emissivity is a key parameter to measure the surface temperature of materials in the radiation thermometry. In this paper, the surface emissivity of metallic substrates is measured by the multi-wavelength emissivity measurement apparatus developed by the Harbin Institute of Technology (HIT). The measuring principle of this apparatus is based on the energy comparison. Several radiation thermometers, whose emissivity coefficients corrected by the measured emissivity from this apparatus, are used to measure the surface temperature of stainless steel substrates. The temperature values measured by means of radiation thermometry are compared to those measured by means of contact thermometry. The relative error between the two means is less than 2% at temperatures from 700K to 1300K, it suggests that the emissivity of stainless steel substrate measured by the multi-wavelength emissivity measurement apparatus are accurate and reliable. Emissivity measurements performed with this apparatus present an uncertainty of 5.9% (cover factor=2).
Collaborated measurement of three-dimensional position & orientation errors of assembled miniature devices with two vision systems
Author(s):
Xiaodong Wang;
Wei Zhang;
Yi Luo;
Weimin Yang;
Liang Chen
Show Abstract
In assembly of miniature devices, the position and orientation of the parts to be assembled should be guaranteed during or after assembly. In some cases, the relative position or orientation errors among the parts can not be measured from only one direction using visual method, because of visual occlusion or for the features of parts located in a three-dimensional way. An automatic assembly system for precise miniature devices is introduced. In the modular assembly system, two machine vision systems were employed for measurement of the three-dimensionally distributed assembly errors. High resolution CCD cameras and high position repeatability precision stages were integrated to realize high precision measurement in large work space. The two cameras worked in collaboration in measurement procedure to eliminate the influence of movement errors of the rotational or translational stages. A set of templates were designed for calibration of the vision systems and evaluation of the system’s measurement accuracy.
Portable calibration instrument of hemodialysis unit
Author(s):
Liang-bing Jin;
Dong-sheng Li;
Ai-jun Chen
Show Abstract
For the purpose of meeting the rapid development of blood purification in China, improve the level of blood purification treatment, and get rid of the plight of the foreign technology monopolization to promise patients’ medical safety, a parameter-calibrator for the hemodialysis unit, which can detect simultaneously multi-parameter, is designed. The instrument includes a loop, which connects to the hemodialysis unit. Sensors are in the loop in series, so that the dialysis can flow through this loop and the sensors can acquisitive data of various parameters. In order to facilitate detection and carrying, the integrated circuit part modularly based on the ultralow-power microcontrollers,TI MSP430 is designed. High-performance and small-packaged components are used to establish a modular, high-precision, multi-functional, portable system. The functions and the key technical indexes of the instrument have reached the level of products abroad.
Segmental calibration for commercial AFM in vertical direction
Author(s):
Yushu Shi;
Sitian Gao;
Mingzhen Lu;
Wei Li;
Xuefang Xu
Show Abstract
Atomic force microscopy (AFM) is most widely applied in scientific research and industrial production. AFM is a scanning probe imaging and measuring device, useful for physical and chemical studies. Depends on its basic structure, microscopic surface pattern can be measured and captured by mechanically scanning. Its vertical and horizon resolution can reach to 0.01nm and 0.1nm. Commonly the measurement values of commercial AFM are directly from scanning piezoelectric tube, so that it not a traceable value. In order to solve the problem of commercial AFM’s traceability, step height standard references are applied to calibrate the piezoelectric ceramic housing in scanning tube. All of the serial of step height standard references, covering the commercial AFM vertical scale, are calibrated by Metrology AFM developed by National Institute of Metrology (NIM), China. Three interferometers have been assembled in its XYZ axis, therefore the measurement value can directly trace to laser wavelength. Because of nonlinear characteristic of PZT, the method of segmental calibration is proposed. The measurement scale can be divided into several subsections corresponding to the calibrated values of the series of step height standards references. By this method the accuracy of measurements can be ensured in each segment measurement scale and the calibration level of the whole instrument can be promoted. In order to get a standard step shape by commercial AFM, substrate removal method is applied to deal with the bow shape problem.
Liquefied Natural Gas (LNG) dispenser verification device
Author(s):
Maotao Xiong;
Jie-bin Yang;
Pu-jun Zhao;
Bo Yu;
Wan-quan Deng
Show Abstract
The composition of working principle and calibration status of LNG (Liquefied Natural Gas) dispenser in China are introduced. According to the defect of weighing method in the calibration of LNG dispenser, LNG dispenser verification device has been researched. The verification device bases on the master meter method to verify LNG dispenser in the field. The experimental results of the device indicate it has steady performance, high accuracy level and flexible construction, and it reaches the international advanced level. Then LNG dispenser verification device will promote the development of LNG dispenser industry in China and to improve the technical level of LNG dispenser manufacture.
Evaluation method of indoor GPS measurement network
Author(s):
Yang Li;
Zili Zhou;
Liqun Ma;
Qian Li
Show Abstract
Indoor GPS measurement network is a space coordinate measuring system, which is composed of more than one transmitter. The number and location of the transmitter determine the measurement range and accuracy of the measurement network. Therefore, how to correctly evaluate the measurement network is a key issue. By analyzing the error model of a measuring system, which is composed of two transmitters, we acquired the main cause of the measurement uncertainty. Through MATLAB simulation, we are able to get the effective measurement conditions, in order to meet specific requirement of measurement uncertainty. Meanwhile, total uncertainty of the measurement network, which is composed of measurement uncertainty, location uncertainty, receiver uncertainty and other uncertainties, is analyzed. We proposed the evaluation method based on the reference length, and at the same time, optimized the position of the reference position, posture and length, in order to meet the evaluation requirements of the entire measurement space. Finally, we simulated the measurement network for aircraft assembly in measurement space of 20m×20m×5m, and the measurement network for car assembly in measurement space of 5m×5m×2m. We evaluated the measurement network according to the above principles and estimated the uncertainty of the measurement network trough measurement bias of reference length at different locations.
A method for calibrating micro-force of nanoindentation instrument using laser interferometer
Author(s):
Dongmei Ren;
Yu Wan;
Zhenyu Zhu;
Qiang Li
Show Abstract
A traceable method for potential use in calibrating the micro-force of nanoindentation instrument using a laser interferometer is proposed. The calibration system consists of a laser interferometer and a cantilever. The cantilever is used as force-sensing element, and the interferometer is used to measure the deformation of the cantilever caused by the force. When a force is applied to the free end of the cantilever, the cantilever is elastically deformed. If the system is calibrated for the relationship between the force and the resulting displacement, it can be used to measure the loading force of a nanoindentation instrument by measuring the displacement of the measurement point on the cantilever. The system calibration can be performed using a set of calibrated masses. The design, calibration and application of the force calibration system are introduced. The experiment results of measuring the forces of a nanoindentation instrument ranging from 10μN to 1mN using this method are given. Preliminary experiments and analysis show that the proposed method can be used to measure the micro-force of nanoindentation instrument. By use of this method, the measurement of the micro-force in nanoindentation instrument can be traced to SI units.
Chromatic confocal surface profilometry employing signal recovering methodology for simultaneously resolving lateral and axial cross talk problems
Author(s):
Liang-Chia Chen;
Tsung-Yi Lin;
Yi-Wei Chang;
Shyh-Tsong Lin
Show Abstract
In this research, novel deconvolution methodology is proposed to resolve the lateral and axial cross-talk problems encountered in line-scanning chromatic confocal surface profilometry. The strategy integrates chromatic confocal principle, infinitive microscopic optics and deconvolution theory to resolve the entangled cross-talk problem in microscopic confocal measurement, so the measuring resolution can be greatly enhanced from the level of the traditional line-scanning up to the one achieved by generally traditional point-type confocal measurement. To overcome the problem, this research analyzes the physical phenomenon of optical near field using photonic spectrum analyses for establishing relationship between the light expansion and propagation depth, as well as light wavelength. In the confocal image, acquired spectrum intensity can be regarded as the convolution between the ideal signal from objects and the point spread function (PSF) of incident light. By employing spectrum analyses, important calibrated characteristics of the PSF along both of the lateral and depth directions can be carefully established. By using the individual PSF for its corresponding wavelength detected at its matching focal depth, the proposed deconvolution method has been proved effective theoretically and experimentally in greatly minimizing the full width half maximum (FWHM) of the depth response curve by more than 25 times, thus significantly improving the accuracy and repeatability of microscopic surface profilometry.
Calibration of transformation matrix in object body coordinate and camera coordinate
Author(s):
Jincheng Song;
Zengyu Sun;
Lei Guo;
Dongwei Wang
Show Abstract
In this paper, a new coordinate system calibration is proposed in order to define the dependence of position between object body coordinate and camera coordinate which can be used in object measurement by the formation of image. Due to existing the fabrication and installation error, it is difficult to make system parallel between object body coordinate and camera coordinate. To resolve it, the deviation of the two coordinate system is demanded to measure detailed. The deviation compensation in the image processing software can ensure the accuracy the pitch angle and azimuth in the destination image of camera measurement system. In order to definite the position, a base coordinate system of theodolite is set by mutual-space measurement principle. After the measurement of theodolite system, a transformation matrix of the base coordinate system can be deduced. Changing the position of the theodolite station and adjusting the cross-screw to infinity, the transformation matrix between the base coordinate and star-sensor coordinate can be deduced by image formation of the destination at infinity. The position relation between object body and camera can be calculated by the transformation matrix. The results of the measurement experiment show that the gauging repeatability is 6' which can meet the system gauging demands.
Error of Archimedes spiral when applied in linearity compensation
Author(s):
Ke Liu;
Xiuzheng Chen;
Jincheng Song;
Yajun Liang
Show Abstract
The polar coordinates equation of Archimedes spiral is ρ = ρ0 + aθ , also known as uniform speed spiral. In a polar coordinate system, the polar radius ρ has linear relation with polar angle θ . This character could be used for linearity compensation in mechanical engineering, or metrical instrument. For example, it could be used for moment linearity compensation, the common configuration has a pivot axis on the pole, and a thin line wrap around the spiral on the turntable. The gravitation of a suspension used as constant pull, and the level polar radius as force arm, then it generates a liner moment when the Archimedes spiral rotating at uniform speed. But as the polar angle of tangent point on the plumb line changes at any moment, the polar radius on level direction isn’t linear with polar angle anymore, and the small error influences the effect of linearity compensation configuration. This paper presented the application of Archimedes spiral in linearity compensation, analyzed the theory error, and deduced the error equation by Mathematic theory. Using computer emulator, educed the precise errors of some dispersed points in common use, and provided according error tabulation. In engineering applications, engineers could consult this error tabulation and correct the points on Archimedes spiral, to realize accurately linearity compensation.
Converting the infrared thermal image into temperature field for
detection the defects inside materials
Author(s):
Terry Y. Chen;
Ming-Hsuan Kuo
Show Abstract
Infrared thermography inspection is a full-field, non-contact method that allows the defects inside the materials to be detected at one time. However, an interface is required to transfer the gray-level represented infrared image into temperature field for further
evaluation. Based on the theory of radiation and the principle of infrared camera’s signal conversion, a method to convert the gray
level represented infrared thermal image into temperature field is developed. Test of the method on a cup of hot water was done. Thetemperature obtained by the proposed method and a commercial ones agree very well with each other. An average error less than 0.9% was achieved between them.
Experimental study on the absolute measurement of spherical surface with high accuracy
Author(s):
Xi Hou;
Weihong Song;
Fan Wu;
Liming Lu
Show Abstract
The absolute measurement of spherical surface with multiple relative measurements is used widely in high accuracy interferometry, which can obtain the absolute surface data of the tested spherical surface. We present an experimental study on the different absolute methods of two-sphere, random-ball-averaging and shift-rotation to calibrate the spherical reference of a same transmission sphere with high accuracy. The experimental results show that the reference surface deviation measured with the different absolute methods agrees well with each other, with the fact that the difference of rms is ~0.6nm.
Evaluation of vibration transducer resolution by using intrinsic microseism
Author(s):
Chenguang Cai;
Jiaping Xu;
Jingsheng Li
Show Abstract
The intrinsic microseism in a precision metrology laboratory of National Institute of Metrology is used to evaluate the resolution of vibration transducers. The precision metrology laboratory is located in the Changping experimental base of National Institute of Metrology. The intrinsic microseism has been measured since 2003. The frequency of the intrinsic microseism is about 3.2 Hz, and the velocity magnitude of the intrinsic microseism is about 5×10-8 m/s. The long term measure proved the frequency and magnitude of the intrinsic microseism is stable, and it can be used as a natural standard to evaluate the resolution of vibration transducers. The vibration transducers and a reference vibration transducer are located in a seismic block. The reference vibration transducer has enough vibration resolution to measure the intrinsic microseism. The vibration transducers and the reference vibration transducer measure and record the ambient vibration at the same time in a measurement period, e.g. 15 minutes, 2 hours or 24 hours. The recorded data are analyzed by FFT with average analysis in full-time process to gain the average spectrum. If the 3.2 Hz intrinsic microseism could be measured by the vibration transducers, the resolution of the vibration transducers will precede the magnitude of the 3.2 Hz intrinsic microseism which is measured by the reference vibration transducer. The signal noise ratio in the average spectrum can further affect the measure results.
Design of the automatic motor Ke measurement system using the system on programming chip
Author(s):
Sheng-Chan Yen;
Kai-Hsiung Chang;
Yen-Chih Liu;
Nia-Chun An;
Hsiu-An Tsai
Show Abstract
The induced electromotive force of traditional motor measurement usually uses another motor to connect the tested
motor with the drive shaft to measure its speed and obtain Ke value of induced electromotive force of the tested motor. If the tested motor is not suitable for connection to the connect coupling because of the shape or volume of the rotor, it is difficult to measure the Ke values of the tested motor. So some scholars have proposed two-phase motor which drives the three-phase motor, and gain the measurement method of Ke from the third phase in a few years ago. The mainly way is using the digital logic circuits to redefine the truth table by entering the signals to the motor driver chip from the three Hall sensors. So it can still maintain a positive torque above 0 even if used the two-phase driver and the motor can be rotated by the two-phase driver. But the drawback is that it can only be measured the fixed Ke value at the same phase. And it has to redefine the truth table to measure the values of the other two phase. This paper provides a new measurement method that made the motor speed accelerate to the measured speed at the beginning and measuring the value of third phases while the rotation is maintained by the other two-phase. The advantage is that it can change the phase of measurement, so it can easily measure the Ke value. And the most of digital components which including processor, keyboard decoder and frequency counter etc can be achieved in FPGA by using SOPC method. It can significantly reduce the complexity of circuit and increase system reliability degree.
Calibration of sensor system used in ultra-precision form measuring instrument
Author(s):
J. Z. Z. Huang;
T. Sun;
B. M. M. Hu;
W. Gu;
L. L. L. Zhang
Show Abstract
Static and dynamic calibration methods of sensor system used in ultra-precision form measuring instrument are investigated. The nonlinear error of sensor system are corrected through static calibration, and the nonlinear characteristic of sensor system is obtained with a piezo nanopositioning stage, then the nonlinear characteristic is stored in a computer in the form of error correction function, while the sensor system works, according to the established error correction function, corrected value of nonlinear error that correspond to the measured point is to be taken out automatically, and the actual measurement data could be compensated by real-time, namely, the dynamic compensation model for nonlinear error could be established. Especially, if the position of measurement data point is not the same as that pre-stored in computer, corrected value could be obtained using linear interpolation. Dynamic calibration of sensor system is performed using the elliptical standards, and in this case the calibration status of sensor system is consistent with its normal measurement status.
Fabrication of diffraction gratings for surface encoders by using a Lloyd’s mirror interferometer with a 405 nm laser diode
Author(s):
Xinghui Li;
Yuki Shimizu;
So Ito;
Wei Gao;
Lijiang Zeng
Show Abstract
To fabricate a scale grating for a surface encoder in a cost-effective way, a blue laser diode with a wavelength of 405 nm is employed in a Lloyd’s mirror interferometer to carry out interference lithography (IL) of the grating. The beams from the laser diode are collimated by an aspherical collimating lens to form beams with a diameter of 50 mm. These beams are then projected towards the Lloyd’s mirror and the grating substrate, which are aligned perpendicularly with each other and are mounted on a rotary stage. One half of the beam directly goes to the grating substrate, and the other half reaches to the grating substrate after being reflected by the mirror. The direct beam and the reflected beam interference with each other to generate and expose the interference fringes, which correspond to the scale grating structures, on the substrate coated with a photoresist layer. The pitch and area of the grating structures are set to be 570 nm and around 300 mm2, respectively. The fabricated grating structures are evaluated with an AFM to investigate the influence of the spectrum width of the laser beam.
High optical transparent and wireless communication band-pass filtering window
Author(s):
Yongmeng Liu;
Yu Han;
Maoqiang Yuan;
Jing Ma
Show Abstract
A high optical transparent and wireless communication band-pass window with hexagon-loop aperture ITO frequency selective surface (FSS) array structure is developed. The parameters of hexagon-loop aperture FSS are designed as h = 5.5mm, w = 0.5mm, d = 2mm according to empirical formula of resonance frequency. The bandpass filtering characteristics of different dielectric-loaded FSS windows with the same dielectric thickness e=0.5mm are simulated and comparatively analyzed. Through calculation results and simulation analysis, it can be found that single-layer dielectric-loaded FSS windows have more stable and desired resonance frequency of 5.8GHz, wider symmetrical bandwidth and independence of incidence angle and polarization than that of double-layer ones at large incidence angles. So it can be concluded that single-layer dielectric-loaded FSS windows are suitable for ISM wireless communication bandpass filtering application.
Characterization of nanoline based on SEM images
Author(s):
Chen-ying Wang;
Shu-ming Yang;
Qi-jing Lin;
Zhuang-de Jiang
Show Abstract
In this paper, nanolines are fabricated on photoresist using electron beam lithography (EBL) technique. The trapeziform of the cross-section is studied through analysis of the top-down scan electron microscope (SEM) image of the nanolines. Width is not adequate to describe the nanolines. From the SEM image it can be observed that the edge of the nanolines is not straight. Fractal dimension is used to describe the line-edge roughness (LER) of the nanolines. Three different methods are used to calculate the width of the nanolines. Comparing three different values and uncertainty, the true value of the nanolines has been found.
Large step structure measurement by using white light interferometry based on adaptive scanning
Author(s):
Yan Bian;
Tong Guo;
Feng Li;
Siming Wang;
Xing Fu;
Xiaotang Hu
Show Abstract
As an important measuring technique, white light scanning interferometry can realize non-contact, fast and high accurate measurement. However, when measuring the large step structure, the white light scanning interferometry has the problems of long time consumption and low signal utilization. In this paper, a kind of adaptive scanning technique is proposed to measure the large step structure to improve its efficiency. This technique can be realized in two ways-the pre-configuration mode and the auto-focusing mode. During the scanning process, the image collection is limited within the coherence area, and in other positions, the motion is speeded up. The adaptive scanning is driven by the nano-measuring machine (NMM) which reaches nanometer accuracy and is controlled by the measurement software. The testing result of 100μm step height shows that the adaptive scanning can improve the measuring efficiency dramatically compared with conventional fixed-step scanning and it keeps the same high accuracy.
Microscopic fringe projection system and measuring method
Author(s):
Jinping Chen;
Tong Guo;
Longlong Wang;
Zhichao Wu;
Xing Fu;
Xiaotang Hu
Show Abstract
Microscopic fringe projection method based on fringe projection and microscopic imaging was proposed to measure the 3D profile of micro-components, which is fast, accurate and non-contact. The measurement system includes two sets of microscope tubes: one for projecting fringe, and the other for imaging. The sinusoidal fringes generated by the software were projected onto the tested object through the DLP projector. The deformed fringes were captured by the CCD camera. The five-step phase shifting method was used for the phase extraction, and the branch cut algorithm was applied for the phase unwrapping process. After system calibration, a coin was measured to show the applicability of the system.
Dynamic analysis of mechanical model for three-dimensional resonant trigger probe and experiment
Author(s):
Huijuan Yu;
Qiang-Xian Huang;
Zhibo Li;
Maocui Wang;
Jin-Peng Wei
Show Abstract
A novel three-dimensional resonant trigger probe, which is fabricated with force sensitive components with good resonant characteristics and an integrated micro-stem and microsphere, is a new type of probe for micro/nano coordinating measuring machine (micro/nano CMM). In this paper, its triggering mechanical models are proposed to simulate the nano interaction between sample surface and the microsphere tip of the probe. In the models, the interaction between the sample surface and microsphere tip in Z direction is presumed in tapping mode (TM) and the interactions in X and Y directions are presumed in friction mode (FM). Taking account of air damping, energy dissipation, restoring force of elastic deformation, nanoscale interface friction, interface adhesion and van der Waals force, the models of the interactions between the microsphere tip and the sample surface in X(Y) direction and Z direction are deduced and constructed respectively. Based on the proposed models, the dynamic analysis on the triggering mechanism of the probe is presented. By experiment, the three-dimensional approaching curves of the probe are observed and they are proven to be suitable for the triggering signals of the probe. Preliminary experimental results show that the trigger resolution of the probe is about 0.24 nm in X direction, 0.20 nm in Y direction and 0.18 nm in Z direction. The theoretical analysis and experimental results demonstrate the validity of the novel resonant trigger probe.
Experimental study on fabricating micro monolithic tungsten probing ball for micro-CMM
Author(s):
Zhi-Wei Wang;
Kuang-Chao Fan;
Rui-Jun Li;
Wei Gong
Show Abstract
Three-dimensional measurement of microstructures requires a 3-D microprobe with small probing ball as well as appropriate nanopositioning and nanomeasuring machines. An electric arc melting method is presented in this paper, which could fabricate the monolithic micro-spherical tip on the tungsten wire. Based on the principles of electrode discharging energy absorption and the surface tension phenomenon, a micro sphere is formed at the needle-shape tip of the tungsten wire. The model of dynamic arc discharging is established to analyze the process of sphere forming. Experiment results reveal that a spherical tip about 60 μm in diameter having less than 1 μm roundness error could be achieved on a 100 μm diameter tungsten wire with the selection of proper process parameters, such as the discharging voltage, discharging time and discharging gap. Quality of the probe is mainly determined by the electro-discharge conditions which affect the solidification force and thermal conductivity. The monolithic microprobe can be used in the micro coordinate measurement machines (Micro-CMMs) to allow the measurement of micro grooves possible.
Methodologies for measuring residual stress distributions in epitaxial thin films
Author(s):
M. Liu;
H. H. Ruan;
L. C. Zhang
Show Abstract
Residual stresses in a thin film deposited on a dissimilar substrate can bring about various interface or subsurface damages, such as delamination, dislocation, twinning and cracking. In high performance integrated circuits and MEMS, a too high residual stress can significantly alter their electronic properties. A proper residual stress characterization needs the description of full stress tensors and their variations with thickness. The problem is that film thickness measurement requires different means, and that direct measurement techniques to fulfill the tasks are not straightforward. This paper provides a simple method using X-ray diffraction (XRD) and Raman scattering for the measurement of residual stresses and their thickness dependence. Using the epitaxial silicon film on a sapphire substrate as an example, this paper demonstrates that the improved XRD technique can make use of multiple diffraction peaks to give rise to a highly accurate stress tensor. The co-existence of silicon and sapphire peaks in a Raman spectrum then allows a simultaneous measurement of film thickness from the peak intensity ratio and the residual stress from the peak shift. The paper also concludes the relation between film thickness and residual stresses.
Long range metrological atomic force microscope with versatile measuring head
Author(s):
Mingzhen Lu;
Sitian Gao;
Qi Li;
Wei Li;
Yushu Shi;
Xingfu Tao
Show Abstract
A long range metrological atomic force microscope (AFM) has been developed at NIM. It aims to realize a maximum measurement volume of 50mm×50mm×2mm with an uncertainty of a few tens of nanometers in the whole range. In compliance with Abbe Principle, the instrument is designed as a sample-scanning type. The sample is moved by a 6-DOF piezostage in combination with a hybrid slide-air bearing stage for long scanning range. Homodyne interferometers with four passes attached to a metrological frame measure relative displacement between the probe and sample thus the instrument is directly traceable to the SI. An AFM head is developed as the measuring head for the instrument. Considering accuracy and dynamic performance of the instrument, it is designed to be capable of scanning perpendicularly in a range of 5μm×5μm×5μm with a 3-DOF piezostage. Optical beam deflection method is used and a minimum of components are mounted on the moving part. A novel design is devised so that the photodetector is only sensitive to the deflection of cantilever, but not the displacement of the head. Moving manner of the head varies with scanning range and mode of the instrument. Results of different measurements are demonstrated, showing the excellent performance of the instrument.
Error analysis and correction of grating interference displacement measurement system
Author(s):
Minlan Jiang;
Xinchao Lu;
Xiaodong Wang;
Xiuling Xu
Show Abstract
Main error source, error characteristics and its correction method have a detailed analysis of the grating interference displacement measuring system in this paper. Through the error separation and compensation method, its system error is modified. Random error is separated through frequency spectrum analysis method. Experimental results show that, the system accuracy can be improved from micron or submicron magnitude to nanometer level by these error correction methods. This system can realize nanometer level measurement.
Character measurement and analyzing of micro optical lenses array fabricated by UV-imprint
Author(s):
Nan Liu;
Peng Jin;
Jiubin Tan
Show Abstract
Micro lens array used in parallel laser direct writing process is fabricated with UV imprinting and dry etching. Experiment results show that the relief of fabrication result is confirmed with that of original stamp. And the optical character test experiments show that the focused spot array under both writing laser and focusing test laser is similar. And the single spot profile under both writing laser and focusing test laser is also similar.
High-temperature SOI pressure sensors on the base of the MEMS micromachining technology
Author(s):
L. V. Sokolov
Show Abstract
There is a need of measuring distributed pressure on the compressor inlet of the aircraft engine with high precision within a wide operating temperature range to improve the efficiency of aircraft engine control. The basic solutions and principles of designing high-temperature (to 250°C) microelectromechanical pressure sensors based on a membrane-type SOI heterostructure (SOIMT-MEMS) with a monolithic integral tensoframe (MT) are proposed in accordance with the developed concept [1] which excludes the use of electric p-n junctions in semiconductor microelectromechanical sensors. The SOIMT-MEMS technology relies on the group processes of microelectronics and micromechanics for high precision microprofiling of three-dimensional micromechanical structure which exclude high-temperature silicon doping processes. According to the design, manufacturing process and experiment results the technology was optimized and a pilot batch of SOIMT-MEMS samples with the regular geometry and without any undercuts of the tensoframe convex angles was manufactured.
Development and calibration of a 3-PSS parallel CMM
Author(s):
Jing Wang;
Penghao Hu;
Songyuan Li;
Xinxin Bao
Show Abstract
A new 3-DOF parallel Coordinate Measuring Machine was proposed in this paper, which could realize 3D measured with only one linear grating and one precision guide. A kind of calibration method based on the distance of two points is proposed. In the scheme gauge block is utilized as benchmark, Gauss-Newton method, a non-linear least square computational method, is used to solve the measuring equation of the CMM, to get the precise parameter of the machine. Experimental results show that this method can effectively improve the over-all accuracy of the 3-PSS CMM. The further study is in process, we will identify the actual values of input parameter errors and mechanical errors in the software compensation.
Reduction of measurement errors with two-channel configuration in the Mueller matrix ellipsometer
Author(s):
Weiqi Li;
Shiyuan Liu;
Chuanwei Zhang;
Xiuguo Chen
Show Abstract
The random noise and the systematic errors caused by azimuthal errors of the optical elements, i.e., the polarizer, the analyzer, or the compensator, would lead to measurement errors in the Mueller matrix ellipsometer (MME). In this paper, we develop the two-channel MME of the optical configuration PCr1SCr2Wp by replacing the analyzer with a Wollaston prism. In the two-channel MME, two intensity spectra would be acquired simultaneously due to the separation and orthogonal polarization of two light beams by the Wollaston prism and are combined to deduce the Mueller matrix. Two figures of merit are derived to evaluate the effects of random noise and systematic errors on the Mueller matrix measurement, and numerical simulations demonstrate that the two-channel MME can give access to higher accuracy by reducing measurement errors due to random noise and systematic errors.
Lidar echo characteristics analysis for stepped terrain
Author(s):
Yudong Jia;
Xiaoqing Zhang;
Yong Lv;
Xiaoping Lang
Show Abstract
According to the gridded discrete processing method, the laser echo characteristics in the case of ladder terrain ground are analyzed theoretically, and the ladder-like terrain echo mathematical model are established. We find from the work that these two peaks of ladder terrain echo curve is the reflecting of ladder and ground respectively, the time interval between wave peaks is determined by the mutations height of terrain. The mutations height is higher, pulse shaping is more obvious, it is also shown that ground reflectivity in the laser spot affects the size of the echo peak mainly, and does not affect the peak location on the curve.
Thermal influence on precise gear transmission
Author(s):
Yong Zhang;
Yetai Fei;
EnMing Miao;
Xiao-rou Zhang
Show Abstract
Conjugate meshing of involute gears is required in precise gear transmission. However, in the working process, the heat generated in friction results in deformation of the tooth profile of the gear, radial and axial deformation of the shaft and bearing. Meanwhile, there is thermal deformation with non-similarity in the gear box that the shafts and bearings are installed on, which leads to a change of the bearing clearance, axis deflection of the shaft and the gear meshing state. As a result of all these effects, vibration and noise are generated in the transmission system, and it intensifies the possibility of damaging the parts. In this paper, mathematical physics methods and thermal elastic theory are employed to analyze the influence of tooth profiles, gear parameters (transmission ratio i, overlapping coefficients ε, backlash jn, etc), gear meshing, working clearance of the bearing (it relates with the initial clearance, tolerance matching, rotational speed, temperature changes, etc) and the shape of the gear box (cylindricity error, axis deflection, etc) caused by the temperature change. The result can be employed in selecting gear parameters and designing the shape of the gear tooth, bearing clearance and shell structure, and it is also helpful to the design of gear transmissions and screw transmissions.
Airborne platform vibration environmental spectrum data processing via bootstrap method
Author(s):
Yanqing Wang;
Zhongyu Wang;
Jianyong Sun;
Jianjun Zhang
Show Abstract
GJB/ Z 126-99 "The inductive methods for environmental measured data of vibration and shock" implemented in 2000 only applying to solve the problem of normal distribution data. However, the actual vibration environmental spectrum data may not follow normal distribution assumption. The authors in this paper focus attention on a new statistical induction method of bootstrap sampling. This method would overcome the problem of requiring a big sample size and typical probability distribution. Then, power spectral density (PSD) upper probability limit of vibration environmental spectrum data was given by this method. The calculation results indicate this method has high reliability at a given confidence level.
Influence of background radiation noise on the measuring accuracy of satellite laser altimeter
Author(s):
Guoqiang Yan;
Yudong Jia;
Yanxiong Niu Sr.;
Pengfei Zhang
Show Abstract
For the echo signals of Satellite laser altimeter, the leading source of noise is the background radiation noise, which mainly comprises the reflection of sunlight by the targets and the atmospheric scattering of sunlight. This paper deals with a theoretical study on the reflection and atmospheric scattering of sunlight. And on the basis, we calculate and simulate the irradiance of extraterrestrial solar spectrum and the respective effects of path zenith angel, solar zenith angle and ground diffuse reflectance on the solar atmospheric radiance, concluding the corresponding relationship between background radiation noise and these parameters, which provides a theoretical basis for the improvement of Satellite laser altimeter.
Application of fiber spectrometers for etch depth measurement of binary computer-generated holograms
Author(s):
V. P. Korolkov;
A. S. Konchenko;
A. G. Poleshchuk
Show Abstract
Novel spectrophotometric method of computer-generated holograms depth measurement is presented. It is based on spectral properties of binary phase multi-order gratings. An intensity of zero order is a periodical function of illumination light wave number. The grating grooves depth can be calculated as it is inversely proportional to the period. Measurement in reflection allows one to increase a phase depth of the grooves by factor of 2 and measure more precisely shallow phase gratings. Diffraction binary structures with depth from several hundreds to thousands nanometers could be measured by the method. Measurement uncertainty is mainly defined by following parameters – shifts of the spectrum maximums that are occurred due to the tilted grooves sidewalls, uncertainty of light incidence angle measurement, and spectrophotometer wavelength error. It is theoretically and experimentally shown that the method can ensure 0.25-1% error for desktop spectrophotometers. However fiber spectrometers are more convenient for creation of real measurement system with scanning measurement of large area computer-generated holograms which are used for optical testing of aspheric optics. Especially diffractive Fizeau null lenses need to be carefully tested for uniformity of etch depth. Experimental system for characterization of binary computer-generated holograms was developed using spectrophotometric unit of confocal sensor CHR-150 (STIL SA).
Measurement verification of line smoothness and surface roughness of micro products fabricated by two-photon polymerization
Author(s):
Tien-Tung Chung;
Chia- Ping Hung;
Chang-Li Tseng;
Chin-Te Lin;
Patrice L. Baldeck
Show Abstract
This paper studies the quality of lines and surfaces fabricated by the two-photon polymerization (TPP) technology.
Micro lines and surfaces fabricated by TPP are accumulation of micro spots, and their external shapes can be simulated
and predicted from manufacturing parameters, such as laser power, exposure time, scanning speed, spot gap, and line gap.
The correctness of predicted shapes is verified by measuring product shapes by SEM and AFM. The purpose of this
study is to find the best parameters for increasing line smoothness and reducing surface roughness. Firstly, the total
energy absorbed in each point within the work piece space is simulated by adding up all the laser spots of the scanning
path. The point with absorbed exposure energy exceeding the resin threshold energy forms a polymerized spot of the
product, and the product shape can be obtained. Secondly, micro lines and surfaces with different manufacturing
parameters are fabricated and product shapes are measured by both SEM and AFM. The simulated shape and the
measured shape of the product with specific manufacturing parameters are compared. Shapes from simulation and
fabrication have the same trend. Results of this study can be applied in manufacturing TPP products with complex shapes
for better surface quality.
