Journals >Optics and Precision Engineering
Contents
2010
Volume: 18 Issue 11
26 Article(s)
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Research Article
System design of intensity modulation spectropolarimeter
SONG Zhi-ping, HONG Jin, and QIAO Yan-li
The parameter design of a Intensity Modulation Spectropolarimeter(IMS) was studied and analyzed in this paper. The basic concept and structure of the IMS were described and the dependence on modulator design, spectrometer selection and system performance was analyzed. By taking an integrated system design for an examplThe parameter design of a Intensity Modulation Spectropolarimeter(IMS) was studied and analyzed in this paper. The basic concept and structure of the IMS were described and the dependence on modulator design, spectrometer selection and system performance was analyzed. By taking an integrated system design for an example,the IMS experimental system was established in the laboratory, the basic concepts and characteristics of the technique were verified and the polarization spectra from a typical light source were also tested. Experimental results show that the polarized degree of the light from a tungsten-halogen lamp collimator is less than 10%, but it is about 100% when the light is polarized by a polarizer in the spectral range of 525-700 nm. These results are coincident with the theoretical results wel1,which verifies the feasibility of method that spectropolarimeter can be realized based on the intensity modulation..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2325 (2010)
Calibration of image vignetting acquired by camera on LED display panel
ZHANG Xin, WANG Rui-guang, CHEN Yu, and WANG Yang
In order to overcome non-uniformity defects arisen from image vignetting captured by a camera in the dot-to-dot correction of a LED display panel, a correction method based on an image smoothing filter algorithm was proposed from the gray distribution rule of vignetting images. Firstly,the imaging principle of CCD on tIn order to overcome non-uniformity defects arisen from image vignetting captured by a camera in the dot-to-dot correction of a LED display panel, a correction method based on an image smoothing filter algorithm was proposed from the gray distribution rule of vignetting images. Firstly,the imaging principle of CCD on the optical data acquisition in the LED display panel was discussed. Then, the principle of smoothing filter in the spatial domain was described based on the analysis of the stability of CCD imaging, and the surface of the image vignetting defect distribution was obtained by a neighborhood average process to the spatial distribution of LED pixels. Finally, the algorithm to complete the correction of image vignetting by using the surface was presented. Experimental result indicates that the display uniformity deviation of the LED display panel is narrowed from 12.9% to 0.73% after the calibration for the image vignetting, which overcomes the “Center dark, Surroundbright” defects on LED display panels and achieves the desired effect..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2332 (2010)
Design of coefficient-adjustable FBG strain sensors
HE Jun, ZHOU Zhi, DONG Hui-juan, ZHANG Guang-yu, and OU Jin-ping
A design method for coefficient-adjustable FBG strain sensors was given out to deal with the problem of the limited scale or precision for a Fiber Bragg Grating(FBG) strain monitor. Theoretical and experimental researches were performed to test the characters of the sensors on long-gauge or high precision,then two kindA design method for coefficient-adjustable FBG strain sensors was given out to deal with the problem of the limited scale or precision for a Fiber Bragg Grating(FBG) strain monitor. Theoretical and experimental researches were performed to test the characters of the sensors on long-gauge or high precision,then two kinds of high qualified FBG strain sensors(slice mode and FRG packaging mode) were developed and fabricated to validate the design. The sensitivity coefficient of each sensor was analyzed,and it was also calibrated by experiments. Finally, the errors between theoretical and experimental sensitivity coefficients were analyzed. Experimental results indicate that the ranges of the long-gauge sensors have increased by 243% and 126%, and the accuracies of the high-precision sensors have reached 0.51 με and 0.52 με,respectively. In the experiments of calibrations,both kinds of sensors show good linearity and repeatability,and the correlation coefficient is up to 0.999..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2339 (2010)
Precise spectral calibration for hyperspectral imager
ZHENG Yu-quan
In order to precisely calibrate the center wavelength and bandwidth of 1024×80 spectral pixels of a prism-dispersive hyperspectral imager, a spectral calibration facility is established, and a spectral calibration method to realize 1 nm wavelength accuracy is presented.Firstly, the spectral line bend and spectral In order to precisely calibrate the center wavelength and bandwidth of 1024×80 spectral pixels of a prism-dispersive hyperspectral imager, a spectral calibration facility is established, and a spectral calibration method to realize 1 nm wavelength accuracy is presented.Firstly, the spectral line bend and spectral line tilt are introduced, and the precise spectral calibration method and data processing algorithms are determined. After the discrete monochrome response values of all spectral pixels are measured with the spectral calibration facility, the relative spectral response curves are fitted with Gauss function. Finally,the center wavelength matrix and bandwidth matrix are established,the dispersive equations of different spatial pixels and the spectral line bend equations of different spectral channels are given with a polynomial fitting,and the spectral line deviation with circumstance temperature variation is experimentally measured. Furthermore,the effect of spectral calibration accuracy on the radio metric calibration accuracy is discussed.Experimental results indicate that the spectral calibration accuracy reaches 1 nm,and the average bandwidth of all pixels is 8.75 nm. The dispersive equation and the spectral line bend are coincident with design values well,in which the spectral line bend value is between 14 and 19 nm and the average is 17 nm.Moreover,the 1 nm center wavelength accuracy can cause less than 1% radiometric calibration deviation for a 3 000 K blackbody calibration source, and 0.25% for a 6 000 K blackbody calibration source.These results can satisfy the spectral calibration requirements of 1 nm wavelength accuracy..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2347 (2010)
Design of VISAR optical system for Shen-Guang-Ⅲ prototype
YAN Ya-dong, ZHANG Fa-quan, HE Jun-hua, and QI Wen-bo
To establish a Velocity Interferometer System for Any Reflector(VISAR) for the shock velocity measurement based on a laser Doppler shift effect, an optical system with a bandwidth of 0.2 nm was designed by using the 532 nm laser illumination. By choosing advisable materials，the fused silica was used in the optical systTo establish a Velocity Interferometer System for Any Reflector(VISAR) for the shock velocity measurement based on a laser Doppler shift effect, an optical system with a bandwidth of 0.2 nm was designed by using the 532 nm laser illumination. By choosing advisable materials，the fused silica was used in the optical system to improve the radiation resistance. Then, the second harmonics of the drive lasers and other stray lights are filtered by band-pass filters and laser line filters. To simplify the system assembly, the modularized design method and a optical gemel hinge were taken to compose models. Furthermore, the 532 nm laser was used for initially adjustment and the white light was used for accurately adjustment to implement the optical path difference to the zero. The proposed system show its total path length is 6.3 m, field of view is φ1.0 mm, and magnifications are 5× and 10×. A static experiment was undertaken, which can offer straight fringes and can give a static contrast above 0.67 and a resolution of 5.3 um. Moreover, a dynamic experiment of the system was carried out on the Shen-Guang laser-Ⅲ facility successfully..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2355 (2010)
Fracture mechanism of fiber terminal-faces and their fabrication
LI Dian-jun, LI Shi-ming, and MENG Fan-jiang
To study and fabricate the fiber terminal-faces in both theory and experiment，the fracture principle of a brittle uniform solid material is analyzed and discussed concretely according to the solid fracture mechanics. It is concluded that the fracture route in a point of the columniform uniform solid material has the chTo study and fabricate the fiber terminal-faces in both theory and experiment，the fracture principle of a brittle uniform solid material is analyzed and discussed concretely according to the solid fracture mechanics. It is concluded that the fracture route in a point of the columniform uniform solid material has the characteristics of stability and uniqueness in spreading trends. A simple fabricating method to cut the optical fiber terminal-faces is proposed, and an experiment device based on the method is developed. During the cutting experiments, the optical fiber terminal-faces are fabricated with different diameters of 0.2 mm, 0.3 mm, 0.6 mm, 0.8 mm and 1 mm. Then,a reading-microscope and visible laser transmission methods are adopted to measure the optical quality of the obtained fiber terminal-faces. The testing results show that the fiber terminal-faces fabricated by this method can well satisfy the practical application requirements and the probability of high quality for these fiber terminal-faces has reached 100%..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2362 (2010)
Prediction of acetamiprid residues by fluorescence spectroscopy based on PLS method
QIAO Xiao-yan, WANG Yan-jing, and LI Gang
To achieve the detection of multi-component pesticide residues, the Partial Least Square(PLS) method was applied to establishing a calibration model of fluorescence spectral measurement systems, and to predict the pesticide residues of acetamiprid by separating the overlapped spectrum in fluorescence spectroscopy of peTo achieve the detection of multi-component pesticide residues, the Partial Least Square(PLS) method was applied to establishing a calibration model of fluorescence spectral measurement systems, and to predict the pesticide residues of acetamiprid by separating the overlapped spectrum in fluorescence spectroscopy of pesticide residues.By taking the predicted residual error square sum as an evaluating criterion, twenty characteristic wavelengths were selected and then the optimal number of principal components and the optimal analysis model were determined by the cross verification method. According to the test of prediction sets (100, 220, 450 mg/kg), predictive values of acetamiprid residues are 101.45, 222.91 and 440.08 mg/kg on the surface of filter paper, and 98.67, 208.56 and 419.22 mg/kg on the surface of tomato. The correlation coefficients between predictive values and true values respectively reach 0.996 and 0.988. The results demonstrate that the method using PLS in fluorescence spectral analysis for measuring the acetamiprid residue has good performance in shorter measuring time, nondestructive testing and higher accuracy and can effectively implement quantitive analysis for complex and multi-component systems..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2369 (2010)
Thermal analysis and verification of CCD components in spectral imagers at steady and transient states
GUO Liang, WU Qing-wen, YAN Chang-xiang, LIU Ju... and PIAO Ren-guan|Show fewer author(s)
As the thermal noise and dark-currents caused by the temperature increment of CCD components will degrade the imaging quality of spectral imagers,a numerical analysis model for the heat transfer in a CCD component was established by the finite element analysis method. According to the design feature and heat transfer pAs the thermal noise and dark-currents caused by the temperature increment of CCD components will degrade the imaging quality of spectral imagers,a numerical analysis model for the heat transfer in a CCD component was established by the finite element analysis method. According to the design feature and heat transfer path in the CCD component,the numerical simulation thermal analysis model of the CCD component was built by a finite element thermal analysis software IDEAS-TMG. Based on the given temperature boundary condition, the thermal analysis of CCD component on steady and transient states was carried out. The thermal response performance of CCD component, steady-state temperature profile and the transient temperature curves of key parts in the CCD component were given. The steady-state thermal analysis shows that the averaged temperature value of CCD device is 27.1 ℃ and the transient thermal analysis shows that the temperature rise coefficient is 2.5 ℃/min, and the highest temperature is 37.8℃. These results are coincident with the analysis results well,and verifies the correctness of numerical simulation and the validity of temperature prediction.Furthermore,the averaged temperature value and the temperature rise coefficient of CCD device on steady and tranisient tests are 26.8 ℃ and 2.4 ℃/min respectively, which demonstrates the results obtained can meet the requirements of heat control, and can supply theoretical warrants for the reliability and optimization of thermal design..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2375 (2010)
Automatic centering of laser particle size analyzers based on four-quadrant construction
GE Bao-zhen, LI Wen-chao, MA Yun-feng, and WEI Yao-lin
As the manual centering of laser particle size analyzers is slow operation and difficult to be adjusted, this paper presents an automatic centering method for the 50-channel photo detector based on a four-quadrant detection unit. According to the different positions of the detectors, the process of automatic centering As the manual centering of laser particle size analyzers is slow operation and difficult to be adjusted, this paper presents an automatic centering method for the 50-channel photo detector based on a four-quadrant detection unit. According to the different positions of the detectors, the process of automatic centering was divided into pre-centering and acute-centering. When the laser beam was out of the sensing range of the detector, the system carried out a pre-centering based on the special structure of the detector; When the laser beam could be sensed by the detector, the system undertook the acute-centering according to the photocurrent intensity from the detector to determine its motion direction. After transition from a pre-centering into the acute-centering, the variable step was used to obtain the best cut-off condition of the automatic centering system by comparing the centering accuracy and centering time. Furthermore, the designs of software and hardware of the laser size analyzer were completed and the reliability and accuracy of the system were verified. The results show that its resolution is higher than 5 μm. Finally, the method was used to test standard particles, and the data after automatic centering meet the requirements of calibration specification for static light scattering particle size analyzers..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2384 (2010)
Test and evaluation of wavefront phase of point diffraction
MA Dong-mei, and CHEN Tu-quan
A testing method was proposed for the diffraction wavefront produced by a pinhole mounted in a point-diffraction interferometer. The producing principle of the point diffraction wavefront was presented, and the relation among the pinhole states, illumination adjustment and the wavefront aberration was analyzed. On the A testing method was proposed for the diffraction wavefront produced by a pinhole mounted in a point-diffraction interferometer. The producing principle of the point diffraction wavefront was presented, and the relation among the pinhole states, illumination adjustment and the wavefront aberration was analyzed. On the basis of the fundamental theory of information optics, the Fourier transform and an iterative algorithm were used to calculate and analyze the pinhole diffuse image, retrieve the phase of diffraction wavefront and then to obtain the wavefront information. The related theory was discussed and the measured point diffraction image was analyzed through a computing software of phase retrieval. Results indicate that the output phase tends to a convergence after about 15 iterations, and the image error factor has dropped to 0.12. The testing method has been applied to the selection of pinholes and the assembly of pinhole illumination systems, and experimental results prove that the testing method is valid..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2390 (2010)
Silicon tuning gyroscope tuned by negative stiffness effect
YANG Bo, WANG Shou-rong, LI Kun-yu, ZHU Xi, and CAO Hui-liang
In order to verify the feasibility of the principle of a silicon tuning gyroscope, the tuning mechanism of the gyroscope, and the oscillation mode and process flows of a silicon rotor were introduced, and the signal detecting circuits and rebalancing control loops of the gyroscope were also researched. Then, a new tuniIn order to verify the feasibility of the principle of a silicon tuning gyroscope, the tuning mechanism of the gyroscope, and the oscillation mode and process flows of a silicon rotor were introduced, and the signal detecting circuits and rebalancing control loops of the gyroscope were also researched. Then, a new tuning method which tuned the silicon tuning gyroscope by the negative stiffness effect from a moment meter was proposed. The tuned theoretical formula by negative stiffness effect was deduced, and the polar plate of a capacitor and the disc rotor with an equilibrium ring were designed, simulated and fabricated. Moreover, the interface circuit of sensing capacitance signals, the voltage booster circuit, feedback correcting circuit and the rebalancing control loop were designed. On the basis of above, a prototype of the silicon tuning gyroscope was achieved. Experiment results prove that the new tuning method based on the negative stiffness effect from moment meter is feasible, and the designs of interface circuits and rebalancing control loops are available. The preliminary performance test of the prototype shows that the scale factor is 1.42 mV/((°)/s), scale factor nonlinearity is 2.47％ and the maximum rate is ±200 (°)/s, which proves that the feasibility of the proposed tuning method for silicon tuning gyroscopes..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2398 (2010)
Prediction system of surface roughness based on LS-SVM in cylindrical longitudinal grinding
HUANG Ji-dong, WANG Long-shan, LI Guo-fa, ZHANG Xiu-zhi, and WANG Jia-zhong
A prediction model of surface roughness based on the Least Square Support Vector Machine(LS-SVM) in cylindrical longitudinal grinding is proposed. By converting the inequality constraints into equality constraints, the model transformes solving the SVM from a Quadratic Programming (QP) problem to a group of linear equaA prediction model of surface roughness based on the Least Square Support Vector Machine(LS-SVM) in cylindrical longitudinal grinding is proposed. By converting the inequality constraints into equality constraints, the model transformes solving the SVM from a Quadratic Programming (QP) problem to a group of linear equations, which simplifies the learning process and improves the calculating efficiency. Experimental results indicate that the construction speed of the prediction model based on LS-SVM is more faster , and the measurement error(MSE) is less 4% and 1.3% than those of the BP neutrol algorithm and BP+GA algorithm,respectively.The method has been used in a intelligent system for cylindrical longitudinal grinding to predict the surface roughness of a workpiece in real time. By calculating the differences of predicating values and giving values and by directing the correct of grinding parameters,it completes a closed loop and intelligent control and obtains good grinding results..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2407 (2010)
Micro-power generator on dielectric electro active polymer
CHEN Ming, LIN Gui-juan, and SONG De-chao
According to the experimental analysis on the energy transformation of Dielectric Electro Active Polymers (DEAPs) from mechanical energies to electric powers in a static-electric field, its mechanism of electric power generation was studied. The electric energies generated from DEAP were quantitatively researched, thenAccording to the experimental analysis on the energy transformation of Dielectric Electro Active Polymers (DEAPs) from mechanical energies to electric powers in a static-electric field, its mechanism of electric power generation was studied. The electric energies generated from DEAP were quantitatively researched, then a mathematical model on the DEAP′s deformation property was established by using the strain energy function theory from the Yeoh model, Mooney-Rivlin model and Ogden model. Furthermore, the mechanical characteristics of DEAPs were discussed in different deformations, and the scavenged energy equation and motion equation were deduced. Finally, on the basis of the power generation mechanism of DEAPs, the prototype of a micro-wind-powered generator adopting the DEAP materials from Danfoss was developed. Experimental results show that the scavenging energy is 13.7 mJ in one cycle when the DEAP is in a strain of 10% and an applying voltage of 1 200 V. These experiments lay the theoretic foundation for actuators, sensors and micro-generators of DEAPs..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2413 (2010)
Test of superconductivity of pick-up coils for STEP accelerometer and their modification
YANG Yong, CAO Xi-bin, WANG Su-wen, D. GILL... and P. WORDEN|Show fewer author(s)
To ensure the fully superconductivity of a 3D superconducting film in the range of working current required by an accelerometer in the STEP mission and to realize the acceleration measurement in an accuracy of 10-18g, the cryo superconductivity of pick-up coils was tested by several experiments. Tested results show thaTo ensure the fully superconductivity of a 3D superconducting film in the range of working current required by an accelerometer in the STEP mission and to realize the acceleration measurement in an accuracy of 10-18g, the cryo superconductivity of pick-up coils was tested by several experiments. Tested results show that there are uperconductivity failures in the 3D film coils. A subsection method was used to test the 2D composition of the 3D film coils separately, by which the locations of superconductivity failures were determined and the reasons why the failures were happened were obtained. Finally, the method to improve the coil design was presented. After modification according to the method, the film coils have turned to be fully superconducting and their allowable superconducting currents are demarcated from -40 mA to 40 mA. With a 300% margin, they satisfy the requirement of the STEP mission for the working current range from -10 mA to 10 mA. Through the test, analysis and modification, the design and manufacture of pick-up coils are finalized, which lays the technical foundation for STEP mission, and completes engineering applications of 3-D superconducting film coils..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2421 (2010)
Adapting adjustment of stiffness for force feedback micro accelerometer
LI Tong-jie, LIU Yun-feng, DONG Jing-xin, and FAN Da
To improve the roborant capacity and the resolution of a micromechanical accelerometer, the nonlinearity of the system was studied. The mathematic model of the system was discussed and the variable electrostatic stiffness brought by the nonlinearity of a electrostatic torque was analyzed. Analytical results show that tTo improve the roborant capacity and the resolution of a micromechanical accelerometer, the nonlinearity of the system was studied. The mathematic model of the system was discussed and the variable electrostatic stiffness brought by the nonlinearity of a electrostatic torque was analyzed. Analytical results show that the preload voltage is used to be less than 0.707 time of crippling load voltage so as to make total stiffness greater than zero, which will cause a poor resolution when the input is near 0g. In view of the nonlinear effect, an adaptive adjustment method in which the total stiffness was kept a constant and the preload voltage and the feedback voltage were renewed every sampling cycle was proposed to improve the stability and resolution of the system. Finally, a digital micro accelerometer based on DSP was developed,then it was tested by using the adaptive adjustment method. Experimental results indicate that the resolution of the accelerameter is improved from 43.2 μg to 11.3 μg near 0g and from 36.4 μg to 12.1 μg near 1g. These data prove the system performance has been improved greatly..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2430 (2010)
Influence of orientation of external magnetic field, position and aggregation of magnetic beads on signal of GMR biosensor
LI Fu-quan, FENG Jie, CHEN Xiang, and SHI Hai-ping
To quantitatively measure the number of magnetic beads and their binding biomolecules by a Giant Magnet Resistance(GMR) biosensor, the influences of the orientation of external magnetic field, the positions and the aggregation of magnetic beads on the biosensor signals should be considered. In this paper, the influenceTo quantitatively measure the number of magnetic beads and their binding biomolecules by a Giant Magnet Resistance(GMR) biosensor, the influences of the orientation of external magnetic field, the positions and the aggregation of magnetic beads on the biosensor signals should be considered. In this paper, the influences of three kinds of factors are simulated using Comsol software and the simulated results show that the signal amplitudes of the biosensor would be reduced by the tilt of external field, the deviation of bead position from the central area of sensor strips, and the aggregation of beads, especial the tilt of external field. When the tilt is 0.5°, the signal will decrease by 80%. Comparing with the simulated results, a GMR biosensor with the width of 5 μm is fabricated. The dependence of signal outputs on the coverage of magnetic beads is measured and results indicate that it is a linear relation with some deviations. Furthermore, the experimental result is 63 μV when the coverage of magnetic beads is 23.6%, which is smaller than the simulated result in 247 μV. Obtained results prove that both kinds of deviations are owing to the three factors. To measure the magnetic beads quantitatively, it suggests that the measuring conditions should be as fellows: making the external magnetic field perpendicular to the sensor plane; keeping the tilt angle unchanged during the measuring process; putting the magnetic beads to concentrate at the central area of the sensor strips; and avoiding the magnetic bead aggregation..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2437 (2010)
Detection of surface defection of solder on flexible printed circuit
HUANG Jie-xian, LI Di, YE Feng, and Zhang Wu-jie
In order to detect the surface defect on the solder of a Flexible Printed Circuit(FPC), an inspecting technology based on image processing was presented. Firstly, all the defects on the FPC were classified into several defection sorts according to their defection characters. Then, the maximum entropy was used to locateIn order to detect the surface defect on the solder of a Flexible Printed Circuit(FPC), an inspecting technology based on image processing was presented. Firstly, all the defects on the FPC were classified into several defection sorts according to their defection characters. Then, the maximum entropy was used to locate the solder and extract the square and color characters. After estimating the effectness of the Grey Level Co-occurrence Matrix(GLCM) on the quantification for color and structure characters, it was introduced to quantify and extract colorific and structural textures for solders. An analysis on experiments indicates that the defective solder is obviously different from the non-defective solder in several kinds of quantified charaters. On the basis of the result obove,the BP neural network was established and four kinds of characters were selected as the input of neural network. After all neural network weight parameters were adjusted to the optimization through sample training, the performance of the proposed defect detection algorithm was finally evaluated in an on-line testing. Test shows that 50 inspecting targets cost 300 ms, and the inspecting accuracy can reach 94.6%. The experimental result demonstrates that proposed method can detect accurately the solder defect with low false alarms, and the efficiency can satisfy the requirement of defect inspection in online and real time..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2443 (2010)
Fabrication of single-crystal silicon vibrating ring gyroscope
ZHANG Ming, CHEN De-yong, and WANG Jun-bo
In order to simplify the fabrication process of a vibrating ring gyroscope and to improve its finished products,a fabricating method combing Deep Reactive Ion Etching(DRIE) and anodic bonding technologies was proposed to fabricate sensor structures. The operating principles of the vibrating ring gyroscope and the technIn order to simplify the fabrication process of a vibrating ring gyroscope and to improve its finished products,a fabricating method combing Deep Reactive Ion Etching(DRIE) and anodic bonding technologies was proposed to fabricate sensor structures. The operating principles of the vibrating ring gyroscope and the technological drawbacks in the traditional fabrication process were discussed. Then, the processing flows based on DRIE and anodic bonding technologies were carefully designed,and the effect of different technological parameter on the gyroscope performance was analyzed. On the basis of the analyzed results,the technological flows and parameters were modified. Finally, a single-crystal silicon vibrating ring gyroscope with a high aspect ratio was fabricated and tested. Experimental results indicate that the proposed method can fabricate a vibrating ring gyroscope with 3 μm capacitance gaps and 80 μm depth.In comparison with traditional fabrication technologies, the number of masks has been reduced from 7 to 2,which meets the device requirements for simplicity and stabilization..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2454 (2010)
Fast orientation of Beidou bi-satellite by extending baseline
ZHANG Xiao-an, LU Liang-qing, and YANG Biao
To verify the feasibility of an ambiguity resolution method for Beidou bi-satellite orientation by extending baseline, an experimental platform was established by using a Beidou carrier phase receiver with two-antennas. A physical experiment scheme was proposed for the extending baseline, which was realized by determinTo verify the feasibility of an ambiguity resolution method for Beidou bi-satellite orientation by extending baseline, an experimental platform was established by using a Beidou carrier phase receiver with two-antennas. A physical experiment scheme was proposed for the extending baseline, which was realized by determining different positions of several antennae with different baseline lengths in the same direction in advance. The results show that it is feasible to determine the ambiguity of a Beidou single difference carrier phase by extending baseline, and the success rate can reach 100% without cycle slips during extending baseline. Moreover, some deterministic factors such as baseline length, orientation duration, and baseline direction on Beidou orientation were verified by the way. It suggests that the baseline length and orientation duration should be prolonged, and the baseline direction should be as near south-north as possible in order to improve the orientation precision. The research work will greatly improve the practical engineering application of Beidou orientation technology..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2461 (2010)
Asymmetrical distribution of noise correlation between digital image and digital camera
CUI Xia-rong
The best model to describe the asymmetrical distribution of noise correlation was explored to improve the accuracy of identifying digital image authenticity by noise correlation.By theoretical analysis and experiments,it was indicated that the beta distribution, gamma distribution and the logarithmic normal distributioThe best model to describe the asymmetrical distribution of noise correlation was explored to improve the accuracy of identifying digital image authenticity by noise correlation.By theoretical analysis and experiments,it was indicated that the beta distribution, gamma distribution and the logarithmic normal distribution could be used to describe the asymmetrical distribution of noise correlation within (0,1］ . Then, three kinds of probability density functions were used to simulate the probability density function curves of the actual asymmetrical distribution of noise correlation. On the basis of the curve modality of probability density function and the value of the least false rate,it was explained that using logarithmic normal distribution to describe the asymmetrical distribution of noise correlation could obtain the best result. Thus a model by using the logarithmic normal distribution to describe the asymmetrical distribution of noise correlation was proposed. Experiment results show that this model can reduce the least false rate over 60% as compare with the model of using generalized chi square distribution, which proves that using a correct model to describe the asymmetrical distribution of noise correlation is an effective approach to reduce the false rate..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2467 (2010)
Design of INS/CNS integrated navigation system for launch vehicle upper stage
ZHANG Li-bin, CUI Nai-gang, L Shi-liang, and PU Jia-lun
As the errors of the Inertial Navigation System (INS) in a launch vehicle upper stage increase significantly with time and cannot meet the requirements of long working hours,an INS/CNS (Celestial Navigation System) integrated navigation system is studied. Firstly, the coordinate systems and the attitude transformation As the errors of the Inertial Navigation System (INS) in a launch vehicle upper stage increase significantly with time and cannot meet the requirements of long working hours,an INS/CNS (Celestial Navigation System) integrated navigation system is studied. Firstly, the coordinate systems and the attitude transformation matrix are defined. Then, the state equation and measurement equation of the integrated navigation system are raised from the INS error propagation equations and measurements of the star tracker and earth sensor. Finally, a semi-physical simulation experiment system with the star tracker in the loop is designed based on Matlab/dSpace simulation environment. Experimental results indicate that the integrated navigation system decreases the inertial navigation position errors from 1.171 9×104 m to 1.036 7×103 m, the velocity errors from 11.282 7 m/s to 3.662 6 m/s, and the attitude errors from 0.1° to 5′. Furthermore,the experimental results show that the integrated navigation system can correct the inertial navigation errors effectively, and also confirm that the INS/CNS integrated navigation system is feasible and appropriate..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2473 (2010)
Load-balancing strategy in SIP measuring & controlling network based on anycast mode of decision set
ZHOU Qin-he, LIU Gui-xiong, and HONG Xiao-bin
To solve the problem that a single optimal target anycast mode tends to cause new load imbalance, a Measuring & Controlling Network Platform(MCNP) based on the Session Initiation Protocol(SIP) was established and its anycast mechanism was analyzed. By integrating network-layer anycast and application-layer anycast,To solve the problem that a single optimal target anycast mode tends to cause new load imbalance, a Measuring & Controlling Network Platform(MCNP) based on the Session Initiation Protocol(SIP) was established and its anycast mechanism was analyzed. By integrating network-layer anycast and application-layer anycast, an load-balancing method based on an optimal decision set was introduced.The anycast objective is a set,which includes many servers to avoid server resources to be seized confusedly. To obtain an optimal decision set, a mathematical model of optimal decision set anycast was established,and the evidence theory was used to anycast the weight. An experimental platform was built to simulate and verify this new method in OPNET simulation environment. The results show that the imbalance rate of server resource occupancy by using the optimal decision setanycast mode has reduced by 31% as compared with that by using a single optimal target anycast mode, which brings an equal distribution of load to different servers and reduces the extra resources for tackling multi-processing in a single individual server..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2482 (2010)
Improvement of fast motion estimation algorithm used in H.264
LI Gui-ju, LIU Gang, and LIANG Jing-qiu
A fast motion estimation algorithm used in H.264，UMhexagonS, is optimized to improve the efficiency of video compression. Firstly, a stop-search technique is used to judge whether the motion estimation of current macro block should be stopped after the initial search point is predicted. Then,the original algorithm is iA fast motion estimation algorithm used in H.264，UMhexagonS, is optimized to improve the efficiency of video compression. Firstly, a stop-search technique is used to judge whether the motion estimation of current macro block should be stopped after the initial search point is predicted. Then,the original algorithm is improved in two respects for macro blocks which need further motion estimation. One improvement is that fewer search points are used in motion estimation by the proposed partition method when multi-hexagon-grid pattern or cross pattern are adopted, and the other improvement is that the search points of square search pattern and extended-hexagon search pattern are reduced according to statistical characteristics of motion vectors. Moreover, the rationality of the partition method is proved. Experimental results show that the average time of motion estimation is reduced by 15.59% compared with that of the original algorithm, whereas, the Peak Signal to Noise Ratio (PSNR) and bit rate remain almost unchanged. The proposed algorithm improves the coding performance and is suitable for various types of video sequences..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2489 (2010)
Three dimensional measurement method combining color trapezoidal phase-shifting with color gray code
SHAN Li-na, YU Xiao-yang, YU Shuang, WU Hai-bin, and CHEN De-yun
By combining the color trapezoidal phase-shifting with the Gray code, a color structured light three-dimensional measurement method was presented to achieve a fast high-resolution non-contact 3D measurement. In the measurement,the measured space was encoded and decoded by combining a color trapezoidal three-step phase-By combining the color trapezoidal phase-shifting with the Gray code, a color structured light three-dimensional measurement method was presented to achieve a fast high-resolution non-contact 3D measurement. In the measurement,the measured space was encoded and decoded by combining a color trapezoidal three-step phase-shifting pattern with two color gray code patterns.The measured space was divided into 64 sub-spaces by two color gray code patterns. Then, the each sub-space was divided into 6 regions by a repeat color trapezoidal three-step phase-shifting pattern, and each region was subdivided into the pixel through the intensity ratio. The encoding patterns and the decoding formulas were provided, and the color structured-light three-dimensional measurement system was set up. Furthermore,the planes with the deepth of 700~950 mm were measured by the proposed method and a color trapezoidal phase-shifting method,respectively.The theoretical analysis, simulation and actual measurement results indicate that the measurement average error of planes is less than 0.9 mm and the measurement standard deviation is less than 1.2 mm. Finally the proposed method was also used in measuring the plaster face and a real hand,and the results show that this method has advantages in a strong anti-interference ability and fast computing speed..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2497 (2010)
Design of fast fractal stereo video coding system
ZHU Shi-ping, and HOU Yang-shuan
A fast stereo video coding algorithm based on fractal video coding was presented in this paper. Firstly, the conventional Circular Prediction Mapping/Non-contractive Interframe Mapping(CPM/NCIM) method was improved,in which frame I of the video sequences was coded based on Discrete Cosine Transform(DCT) and the others A fast stereo video coding algorithm based on fractal video coding was presented in this paper. Firstly, the conventional Circular Prediction Mapping/Non-contractive Interframe Mapping(CPM/NCIM) method was improved,in which frame I of the video sequences was coded based on Discrete Cosine Transform(DCT) and the others were partitioned into subblocks by a tree structured partition method . In the stereo video encoding, the left channel was a base layer and the right channel was a enhanced layer. The left channel was encoded by using the Motion Compensation Prediction(MCP) method,and the right channel was encoded by using both MCP and Disparity Compensation Prediction(DCP) methods. In the encoding of DCP, the polarization property and the epipolar line property in the parallel stereo encoding structure was used of to simplify the DCP search method. Therefore, a fast DCP encoding method was presented. The experiment results indicate that the computational complexity by the proposed method has reduced to 0.028-0.029 times comparing to that of the full search method while the reconstructed image quality is as good as that in the full search,which makes the stereo video encoding method more useful..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2505 (2010)
Calibration and experiment of vision measurement accuracy for motion of rocket nozzle
LIU Bo, YE Dong, CHEN Gang, and CHE Ren-sheng
On the basis of the novel dual axes rotating and single axis translating calibration equipment, a calibration method for vision measurement of the motion of a rocket nozzle was proposed. Firstly, the motion metric from the calibration equipment and the measured values from vision system were mapped in the space,then thOn the basis of the novel dual axes rotating and single axis translating calibration equipment, a calibration method for vision measurement of the motion of a rocket nozzle was proposed. Firstly, the motion metric from the calibration equipment and the measured values from vision system were mapped in the space,then the position and pose relations between the world coordinate system of stereo vision and the coordinate system of nozzle were deduced. After solving the pose matrix and translation vector, the vector angle coordinate system of the nozzle was established in vision measurement system. Subsequently,by sending a trigger signal and a synchronized time signal from the calibration equipment to cameras, the sampling time was synchronized, and the dynamic data were directly compared. Finally, the experiment for calibrating the vision measurement system was completed.The measurement errors of rotation center and vector angle in nozzle motion space ±12° were analyzed. The experiment results indicate that the max error of vector angle is 0.093° and the max error of rotation center position is 0.832 mm..
Optics and Precision Engineering
- Publication Date: Sep. 19, 2021
- Vol. 18, Issue 11, 2513 (2010)
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