This PDF file contains the front matter associated with SPIE Proceedings Volume 8759, including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

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.

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.

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.

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.

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.

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.

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 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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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 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.

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.

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 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.

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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%.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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 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.

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 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 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°.

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 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%.

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.

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.

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.

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.

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.

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.

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.

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.

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 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 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.

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.

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.

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-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.

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.

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.

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 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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.