Journals >Optics and Precision Engineering
Contents
2009
Volume: 17 Issue 7
42 Article(s)
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Research Article
Manufacture for light splitting grating in optical disk based on precision ruling and thin film deposition
WU Na, ZHANG Shan-wen, SONG Ke-ping, Bayanheshig... and GAO Jian-xiang|Show fewer author(s)
A manufacturing method for a light splitting grating based on precision ruling and thin film deposition technologies was presented.The black-white grating with a duty cycle of 0.5 was ruled by a ruling machine on the metal film,then,it was fabricated into a mask for the light splitting grating.After exposuring and deveA manufacturing method for a light splitting grating based on precision ruling and thin film deposition technologies was presented.The black-white grating with a duty cycle of 0.5 was ruled by a ruling machine on the metal film,then,it was fabricated into a mask for the light splitting grating.After exposuring and developing photoresist on the K9 glass behind the mask,the rectangle relief grating consisting of photoresists was formed.In the range of theory design error,a SiO2 rectangle grating master could be obtained a after SiO2 film was deposited on the relief grating and the rest photoresists were removed.Finally,an epoxide resin light splitting grating was duplicated successfully.The experimental results show that the error of the intensity ratio of secondary light beam to read-write main light beam can be controlled in ±0.03 by using the complementarity of the mismatching tolerance between lengthwise direction and cross direction of the light splitting grating..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1497 (2009)
Infrared testing for translucent material coating
LI Yan-hong, ZHAO Yue-jin, and ZHANG Cun-lin
In order to measure the coating thicknesses on various substrate materials at a high speed and a large area,an active infrared thermographic technique was presented.A light pulse was used to heat to the surface of the coating and an infrared camera was utilized to capture the surface temperature change on real time.ForIn order to measure the coating thicknesses on various substrate materials at a high speed and a large area,an active infrared thermographic technique was presented.A light pulse was used to heat to the surface of the coating and an infrared camera was utilized to capture the surface temperature change on real time.For a translucent coating,visible light could not be absorbed well on the surface,so a water-soluble black paint was painted on the surface of the coating.Compared with the differential lnT -lnt curves without painting the coating,the thickness of the painted coating can be measured according to the peak time of second differential ln T - ln t curves.Experiment results indicate that the translucent coating after painting satisfies infrared testing requirements,and the measurement precision is 0.09 mm for the thickness ranges of 0.8-1.7 mm.These data show that the infrared testing can be used in measurement of the coating thickness at high speeds,large areas,noncontact and quantification..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1502 (2009)
Optical properties of several fluoride materials
XUE Chun-rong, YI Kui, SHAO Jian-da, and FAN Zheng-xiu
Several kind of wide band-gap fluoride materials are studied to determine optical constants of fluoride films in deep ultraviolet(VUV) to ultraviolet(UV). High-refractive-index materials LaF3,NdF3,and GdF3 and low-refractive-index materials MgF2,AlF3,and Na3AlF6 single thin films are deposited by a resistive-heating boSeveral kind of wide band-gap fluoride materials are studied to determine optical constants of fluoride films in deep ultraviolet(VUV) to ultraviolet(UV). High-refractive-index materials LaF3,NdF3,and GdF3 and low-refractive-index materials MgF2,AlF3,and Na3AlF6 single thin films are deposited by a resistive-heating boat on JGS1 and single crystal MgF2 substrates respectively at different deposited rates and specific substrate temperatures.Transmittances of all fluoride thin films are measured through a commercial spectrometer in the ambient atmosphere and wavelength regions from 190 nm to 500 nm,and measured through synchrotron radiation under vacuum in the wavelength regions from 120 nm to 300 nm.The optical constants of these materials are determined by a envelope method and a simulated annealing method,which matches the calculated and measured values of the transmittance.Measured results indicate that the refractive indexes are about 1.77~1.89 at 157 nm for LaF3,NdF3,and GdF3 single layer films,and are about 1.44~1.48 at 157 nm for MgF2,AlF3,and Na3AlF6 single layer films. Experiments show also that these high and low index materials can be composited to material pairs to design and manufacture the cost-effective,mechanically and optically stable optical coatings in 120 nm to 500 nm for new thin devices..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1507 (2009)
Research on mechanical-induced long period fiber gratings
JIANG Ming-shun, FENG De-jun, and SUI Qing-mei
With the aim to study the characteristics of Mechanically Induced Long-period Fiber Gratings (MLPFGs),the MLPFGs are fabricated based on the micro-curve principle.The grooved plates are made by the mechanical line processing technology and the MLPFGs are fabricated by pressing a plate with periodic grooves against a shWith the aim to study the characteristics of Mechanically Induced Long-period Fiber Gratings (MLPFGs),the MLPFGs are fabricated based on the micro-curve principle.The grooved plates are made by the mechanical line processing technology and the MLPFGs are fabricated by pressing a plate with periodic grooves against a short length of fiber.Then,the relationship between MLPFG spectra and fabricated parameters,such as groove periods,period numbers,and pressures are studied.Finally,the influences of the temperature on the MLPFGs made from jacketed and unjacketed fibers are researched.Experimental results indicate that the produced MLPFGs have the insertion loss less than 0.5 dB and the loss peak as high as 16 dB.Moreover,a large tunability of the resonant wavelengths (>14 nm) has been achieved through adjusting the pressure grooves' period.The temperature sensitivities of the resonant loss peaks are 0.230 dB/℃ and 0.312 dB/℃,and the temperature sensitivities of the resonant wavelengths are 0.057 nm/℃ and 0.086 nm/℃ for jacketed and unjacketed fibers,respectively.These results show that this technique is able to control the grating isolation loss peaks and have a certain potential application value in the fiber sensing region for its characteristics by easy erasure and low costs..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1513 (2009)
Thermo-optical testing of Hα and white telescope
WU Ming-chang, YANG Shi-mo, CHEN Zhi-yuan, GU Xue-dong, and WANG Shen
The Hα and White Telescope(HWT) is one of the payloads of the Chinese Space Solar Telescope(SST).To study the impact of the thermal environment on the optical performance of the HWT,the temperature conditions of the thermo-optical testing are designed on the basis of the measurement and numerical simulation of the grouThe Hα and White Telescope(HWT) is one of the payloads of the Chinese Space Solar Telescope(SST).To study the impact of the thermal environment on the optical performance of the HWT,the temperature conditions of the thermo-optical testing are designed on the basis of the measurement and numerical simulation of the ground observing condition.A thermo-optical testing system is established to test the optical performance of the HWT under a thermal vacuum condition.The thermo-optical testing system comprises mainly four sub-systems: an optical system to be tested,a vacuum system,a temperature measurement and control system,and a wavefront sensing system.The optical performance of the five important structures in the HWT system at the different temperature conditions is investigated,including the wedges,secondary mirror,primary mirror,collimation lens,and the imaging lens.The results show that when the temperature of the secondary mirror is lower than 40 ℃,the optical performance of HWT is about λ/8,which satisfies the requirement of λ/6.This paper implements a thermo-optical testing procedure for the HWT under different temperature control conditions.The design ideas and test methods are also applicable in similar optical telescope designs for the solar observation..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1519 (2009)
Development of optical particle counter with double scattering angles
LI Xue-bin, GAO Yi-qiao, WEI He-li, JI Yu-feng, and HU Huan-ling
A new Optical Particle Counter(OPC) with 60° and 110° double-scattering angles was developed in the paper for measuring aerosol refractive indexes and size distributions synchronously.On the basis of defining a sensitive function by Mie scattering theory,two optimum scattering angles were selected,then,the diA new Optical Particle Counter(OPC) with 60° and 110° double-scattering angles was developed in the paper for measuring aerosol refractive indexes and size distributions synchronously.On the basis of defining a sensitive function by Mie scattering theory,two optimum scattering angles were selected,then,the difference of two sattering angles sensitive to aerosol refractive indexes was used to inverse the aerosol refractive indexes.Finally,a prototype with 60° and 110° double scattering-angle of OPC (D-OPC) was used in the experiments at Hefei for measuring aerosol refractive indexes and size distributions.The scattering and absorption coefficient values measured by the D-OPC were compared with that measured by an Aethalometre and an Integrating Nephelometer(designed by TSI).The comparison results indicate that measured data by the D-OPC are reasonable and the measuring error is less than 20%,which shows the D-OPC can satisfy the requirements of measurement of aerosol refractive indexes and size distributions synchronougly..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1528 (2009)
Fabrication and performance analysis of tapered POF connector
ZENG Yong-xi, and ZHUANG Qi-ren
Plastic Optical Fiber(POF) tapered connectors can be used as the connection devices of POFs and quartz optical fibers,so this paper introduces the fabrication and performance of tapered POF connectors.A gravity vertical fused elongated taper method is used to fabricate the tapered POF connectors,and the optimal technicPlastic Optical Fiber(POF) tapered connectors can be used as the connection devices of POFs and quartz optical fibers,so this paper introduces the fabrication and performance of tapered POF connectors.A gravity vertical fused elongated taper method is used to fabricate the tapered POF connectors,and the optimal technical parameters are also obtained under the laboratory conditions.It is found that the process of POF stretching is easy to be controlled and the tapered POF connectors show its good optical quality when the control voltage is 6.0 V,the heating zone center temperature is about 214 ℃ and the stretch strength is about 1.40 g.Experiments prove that the transmission rate of the POF with a fine surface morphology decreases with increasing taper angles,its out light modes decreases,the out light mode intensity is on the low rank modes,and the losses from the visible light transmission spectrum increases in the ranges of 400 to 500 nm.These results show that the gravity vertical fused elongated taper is a effective way to fabricate the tapered POF connectors,and the obtained technical parameters from the experiments can provide the references for the actual productions of POF connectors or POF couplers..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1535 (2009)
Solar simulation technique for solar cell measurement
WANG Zhi-ming, GONG Zhen-bang, WEI Guang-pu, and LIU Li-ming
In order to improve the performance of a solar simulator to measure the characteristic parameters of solar cells more accurately,how to control the radiation parameters for the simulator lamp was studied,such as the radiation utility rate,radiation uniformity,radiation intension,radiation stability,and so on.A coaxial In order to improve the performance of a solar simulator to measure the characteristic parameters of solar cells more accurately,how to control the radiation parameters for the simulator lamp was studied,such as the radiation utility rate,radiation uniformity,radiation intension,radiation stability,and so on.A coaxial optical system was selected as the optical system of the solar simulator.Then,the utility rate the lamp radiation and radiation uniformity were improved by ameliorating the optical system structure layout and increasing an optical integrator.On the basis of analyzing the existing control circuit of the simulator,an optical feedback technology was adopted to redesign the control circuit and to improve the control ability on radiation intension and radiation stability.The experimental results indicate that the new solar simulator can effectively control radiation intension and stability.When the standard light intension is 1000 W/m2,the radiation uniformity is 2.5% and the radiation stability is less than 1% in a diameter of 250 mm,which has greatly improved the performance of the solar simulator..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1542 (2009)
Two-dimensional actuation of liquid using surface acoustic wave
GAO Yang, LI Yi-gui, and ZHANG Jun-feng
This paper reports the two-dimensional actuation of a water drop by using a Surface Acoustic Wave(SAW).Four Interdigital Transducers (IDTs) is fabricated on a 127.8° rotated Y-cut X-propagation LiNbO3 substrate.Each IDT is composed of 10 strip electrode pairs,which is 400 μm in pitch,100 μm in electrode strip widtThis paper reports the two-dimensional actuation of a water drop by using a Surface Acoustic Wave(SAW).Four Interdigital Transducers (IDTs) is fabricated on a 127.8° rotated Y-cut X-propagation LiNbO3 substrate.Each IDT is composed of 10 strip electrode pairs,which is 400 μm in pitch,100 μm in electrode strip width and 12 mm in aperture.The overall size of the device is 26 mm×26 mm×0.45 mm.Due to the anisotropy of LiNbO3 crystal,the resonance frequencies of IDTs are in 9.3 MHz along Y axis and 9.6 MHz along X axis,respectively.Being superior in characteristics to alunimium,copper is used as the electrode material in fabrication process and the Lift-off process is adopted to fabricate electrodes,so that optimum process parameters are finally obtained.An ultra-long-time ultrasonic assistance is used to get rid of residues completely,finally,a two-dimensional actuation of the water drop is observed,which shows the input power is 9 W and the average speed is drop movement is 5 mm/s.The propagation of SAW in LiNbO3 substrate is simulated with ANSYS,simulation result agrees well with the calculation of theoretical vibration amplitude in LiNbO3.This research demonstrates that the two-dimensional acuation of a liquid drop by using the SAW is feasible.This prototype of liquid actuation is promising in lab-on-chip and μ-TAS applications..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1548 (2009)
Calibration equipment for rocket nozzle motion testing and its error analysis
LIU Bo, YE Dong, and CHE Ren-sheng
The 3D motion parameter measurement of a rocket motor nozzle is a premiss for accurately controlling the nozzle,and the calibration equipment is the key to ensure motion testing at a high precision.To test accurately 3D motion parameters,this paper proposes a new calibration equipment to directly simulate the actual moThe 3D motion parameter measurement of a rocket motor nozzle is a premiss for accurately controlling the nozzle,and the calibration equipment is the key to ensure motion testing at a high precision.To test accurately 3D motion parameters,this paper proposes a new calibration equipment to directly simulate the actual motion of the rocket motor nozzle and to supply the standard position and motion parameters for static and dynamic calibrations.After analyzing the motion of the rocket motor nozzle,a new mechanism consisting of a base,a lifting table,a swing table and a standard nozzle model is proposed,which concludes three degrees of freedom,rotation on X and Y coordinate axes,lifting on Z coordinate axis.The terminal error expression is derived by the theory of multi-system kinematic error in consideration of the geometric errors effect on pointing errors and nozzle center position errors,then the origin of geometric errors is analyzed.By the simulated results,the distribution states of pointing errors and center position errors in rotation ranges are obtained.On the basis of the obtained results,it suggests that the orthogonality errors mostly influncing pointing errors should be controlled below 15″,and the axis intersection errors mostly influncing center position errors should be controlled below 80 μm..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1553 (2009)
Modeling and hybrid control of aircraft simulation with input constraints
ZHANG Liu, JIN Guang, and ZHENG Liang-liang
In order to control the flight attitude for an aircraft,a ground semi-physical flight attitude simulation system was established based on a dSPACE system.The invariant set principle and Passivity-based Controller (PBC) design method was used to deal with the aircraft simulation system,for it was a kind of higher order In order to control the flight attitude for an aircraft,a ground semi-physical flight attitude simulation system was established based on a dSPACE system.The invariant set principle and Passivity-based Controller (PBC) design method was used to deal with the aircraft simulation system,for it was a kind of higher order nonlinear control system with strong coupling.A nonlinear Euler-Lagrange (EL) dynamic model with controller constraints for the aircraft simulation system was established by the Largange method.Then,based on the internal characters of EL systems and the recent results on invariant set stability theorems of nonlinear impulsive hybrid systems,a saturation dynamical hybrid controller for the aircraft simulation system was presented,and the mathematic simulation was also given out to verify the effect of the proposed controller.Finally,a semi-physical simulation experiment was undertaken with the proposed controller.Obtained results show that the dynamic response time is about 20 s,steady-state accuracy is less than 5% and the overshoot is about 25%.These data indicate that the designed saturation controller is valid and robust to both the system parameter errors and disturbance..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1561 (2009)
Measurement of relative poses between two non-cooperative spacecrafts
XU Wen-fu, LIU Yu, LIANG Bin, LI Cheng, and QIANG Wen-yi
A stereo vision-based method was proposed to measure the relative poses (position and attitude) between the two non-cooperative spacecrafts to solve the problem of the non-cooperative target recognition for the on-orbital maintenance and space debris removal. A median filter was used to smooth the original images by reA stereo vision-based method was proposed to measure the relative poses (position and attitude) between the two non-cooperative spacecrafts to solve the problem of the non-cooperative target recognition for the on-orbital maintenance and space debris removal. A median filter was used to smooth the original images by removing the disturbance of orbital background and other noises.The edges in the smoothed images were detected using the Canny edge detector to obtain the corresponding binary images.Then,the straight lines of the object to be recognized were extracted from the binary images through Hough transform,and the intersection points among these lines were determined.Finally,the feature points in the left and right images were reconstructed in 3D to obtain the coordinates of the object points in the world frame.Based on these points,the target frame was defined and the pose of the target with respect to the world frame was determined.Simulation results indicate that the position errors are lower than 40 mm in the farther distance (>2.5 m) and 10 mm in the nearer distance (<2.0 m),and the orientation errors are less than 2°,which satisfies the requirements of pose measurements during the tracking,approaching and flying round the non-cooperative target..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1570 (2009)
Quick coarse north-seeking based on intelligent gyro theodolite system
FENG Li, DONG Gui-mei, LIN Yu-chi, ZHANG Jin-mei, and QI Yong-yue
The coarse north-seeking time of a mechanical gyro theodolite is an important factor to decide north-seeking efficiency.A quick coarse north-seeking method named curve fitting is brought into the intelligent gyro theodolite system in this paper.By the proposed method,the true north value can be obtained in 10 s after gThe coarse north-seeking time of a mechanical gyro theodolite is an important factor to decide north-seeking efficiency.A quick coarse north-seeking method named curve fitting is brought into the intelligent gyro theodolite system in this paper.By the proposed method,the true north value can be obtained in 10 s after gyro operates through a counting cursor to calculate the movement velocity and acceleration,and it can also compensate the low precision caused by an electronic compass.The experiment using JT-15 gyro shows that the measurement precision is superior to 3′54″ when seeking coarse north,which meets the precise north-seeking condition of the JT-15 gyroscope.The application of the curve fitting method to the auto north-seeking system can ensure the velocity and precision of north-seeking automatically,and also has realistic significance to improve the efficiency and automation for mechanical gyro theodolites..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1582 (2009)
Chemical mechanical polishing for silicon wafer by composite abrasive slurry
XU Xue-feng, MA Bing-xun, HUANG Yi-shen, and PENG Wei
In order to increase the polishing rate for a silicon wafer,the composite abrasive slurry was used in Chemical Mechanical Polishing(CMP).Zeta potentials of silica abrasives and polystyrene particles in the slurry were measured at various pH values,and the mechanism of interactions between silica abrasives and polymer pIn order to increase the polishing rate for a silicon wafer,the composite abrasive slurry was used in Chemical Mechanical Polishing(CMP).Zeta potentials of silica abrasives and polystyrene particles in the slurry were measured at various pH values,and the mechanism of interactions between silica abrasives and polymer particles was analyzed.Small silica abrasives were observed to attach onto the surfaces of the polystyrene particles and some resin particles.Then,the composite abrasive slurry was obtained by adding some polymer particles into single abrasive slurry.In comparison with the polishing performance of traditional CMP and CMP using composite abrasive slurry,the mechanism of material removal of CMP using composite abrasive slurry was proposed,and the influence of craft parameters on the polishing rate was studied through the experiments.Experimental results indicate that the polishing rate is 180 nm/min with single silica abrasive slurry,and 273 nm/min,324 nm/min with the silica abrasive/polystyrene particle composite slurry and silica abrasive/ resin particle composite slurry respectively.These data show that the removal rate with composite abrasive slurry is improved significantly and the wafer surface roughness Ra is 0.2 nm..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1587 (2009)
Dynamics of hyperstatic parallel six-component force sensor
HOU Yu-lei, ZENG Da-xing, YAO Jian-tao, SUN Feng-long, and ZHAO Yong-sheng
A novel structure of hyperstatic parallel six-component force sensor based on the Stewart platform was proposed,and its theoretical dynamics analysis and finite element simulation were performed.The structure feature of the sensor was described in comparison with the classical Stewart platform-based six-component forceA novel structure of hyperstatic parallel six-component force sensor based on the Stewart platform was proposed,and its theoretical dynamics analysis and finite element simulation were performed.The structure feature of the sensor was described in comparison with the classical Stewart platform-based six-component force sensor.By using the finite element method,the elastic dynamics theoretical model of the sensor was established based on the conditions of displacement consistency and force balance.According to this model,the numerical analysis was carried out,and the variety relationship curves between the natural frequencies and the structural parameters are plotted.By using a ANSYS software,the finite element model of the sensor was built to analyze the vibration modal of the sensor,and the natural frequencies and the vibration modes were obtained.The research results establish the foundation for the further dynamics analysis and synthesis of the sensor and the dynamic optimization design of the sensor..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1594 (2009)
Test of nanomechanical properties of single crystal silicon
ZHAO Hong-wei, YANG Bai-hao, ZHAO Hong-jian, and HUANG Hu
The testing methods for nanomechanic properties of materials widely used in machining in micro-nano scale,MEMS/NEMS,biomedical engineering,material sciences etc.are researched and the main principle and methods of nanoindentation technology are analyzed.By a four-sided Vickers diamond indenter with a sharpened tip,the The testing methods for nanomechanic properties of materials widely used in machining in micro-nano scale,MEMS/NEMS,biomedical engineering,material sciences etc.are researched and the main principle and methods of nanoindentation technology are analyzed.By a four-sided Vickers diamond indenter with a sharpened tip,the nanoindentation experiments are undertaken to test the single crystal silicon on (100) crystal surface with the help of a nanoindentation tester.Experiments show that the brittle crack is occurred around the nanoindentation zone on silicon surface when the maximum load of indentation is 1 000 mN.However,the crystal silicon shows plastic property when the maximum load of indentation is below 80 mN.Moreover,the hardness test of the crystal silicon with different loads is carried out,and the testing results show that the hardness is quite different in different loads.It is explained that the appeared phenomenon may come from the phase transformation under the nanoindentation zone inside the silicon wafer,because the pressure around the nanoindentation zone is different.The testing result of the hardness of single crystal silicon is about 15.7 GPa..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1602 (2009)
Comparison of effects of different young's moduli on stress and displacement of composite flywheel
LI Cheng, WAN Zhi-chao, ZHENG Yan-ping, and TIE Ying
The influences of different Young's moduli on the distribution of the stress and displacement of a composite flywheel was investigated in this paper.According to the heterogeneous anisotropy elastic theory and design features of the flywheel,the computation formulas for the stress and displacement of the composite The influences of different Young's moduli on the distribution of the stress and displacement of a composite flywheel was investigated in this paper.According to the heterogeneous anisotropy elastic theory and design features of the flywheel,the computation formulas for the stress and displacement of the composite flywheel were established at working speeds,and the radial stress,circumferential stress and radial displacement at an arbitrary point were presented.Then,based on the computation models above,the influences of different positions and rotational speeds on the radial stress,circumferential stress and radial displacement were discussed.It is concluded that the radial stress,circumferential stress and radial displacement all increase with increasing of angular velocity from 0 to 5 000 rad/s.The maximal radial stresses of two kinds of materials all occur at the exterior margin of flywheel and the maximal circumferential stresses occur at the inner margin of flywheel.Moreover,under the situation of high Young's moduli(Er=100 GPa,Eθ=350 GPa),radial and circumferential stresses are all higher than that of low Young's moduli (Er=20 GPa,Eθ=150 GPa),whereas,the displacement shows an oppisite change..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1609 (2009)
Key techniques of star sensors for celestial navigation
LI Bao-hua, LIU Guo-liang, LIU Rui, and WANG Chang-hong
Star sensors may work in star tracking cases and predictive centroiding algorithm cases when it has sufficient attitude knowledge,which not only can increase the update rates of star sensors,but also can improve recognition performance.A novel star tracking algorithm for a star sensor with a large angle manoeuver is prStar sensors may work in star tracking cases and predictive centroiding algorithm cases when it has sufficient attitude knowledge,which not only can increase the update rates of star sensors,but also can improve recognition performance.A novel star tracking algorithm for a star sensor with a large angle manoeuver is presented to avoid disadvantages of classic star tracking algorithms.In order to decrease noise errors of the star sensor,the filtering algorithms for star images and star locations are presented.The experimental results show that the star locations are obtained in the threshold scan window 10 pixel×10 pixel in the star image and the attitude accuracy of the star sensor is improved by 5″ in the star image filtered by C-L wavelet,when the spacecrafts are rolled with a angle velocity of 2.25°/s.These algorithms are tested at night sky experiments in 2007 and in 2008 and will be used in the attitude control system of a satellite in 2009..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1615 (2009)
Experiments of ultra-precision turning of SiCp/Al composites
GE Ying-fei, XU Jiu-hua, and YANG Hui
The ultra-precision machinability of SiCp/Al composites is investigated experimentally.A scanning electron microscope (SEM) is used to examine the machined surfaces,chips,chip roots and tool wear lands,and a surface profiling instrument is taken to measure the surface profile roughnesses in different turning conditionsThe ultra-precision machinability of SiCp/Al composites is investigated experimentally.A scanning electron microscope (SEM) is used to examine the machined surfaces,chips,chip roots and tool wear lands,and a surface profiling instrument is taken to measure the surface profile roughnesses in different turning conditions.The results show that the machined surface remains a lot of defects such as pits,voids,microcracks,grooves,protuberances,matrix tearing,etc.The tool geometries,cutting speeds,feed rates,particle reinforcement sizes and the volume fractions are the significant influence factors of surface roughness.Generally,a segmental chip is formed in turning composites due to the effect of dynamic microcrack behavior.The tool-workpiece relative vibration and the removal modes of SiC particles are the main mechanisms of surface generation.The microwear,chipping,peeling and the abrasive wear are the main wear patterns by using the Single Crystal Diamond (SCD) tool,while Polycrystalline Diamond (PCD) tool mainly suffers from the abrasive wear on the rake face and the adhesive wear on the flank face.The experimental result indicates that the SiCp/Al composites has a relatively bad machinability.However,when the cutting parameters are rationally chosen,a surface roughness Ra of 24.7 nm can be obtained for SiCp/2024Al(in a volume fraction of 15%)..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1621 (2009)
Error analysis on numerical double integration in acceleration measurement with clock jitter
TAN Xiao-yun, ZHOU Xian-zhong, XU Na, CHEN Wei-ping, and LIU Xiao-wei
The positioning error of accelerometers due to a clock jitter is analyzed by Monte Carlo analysis method.The simulation results reveal that the distribution of acceleration measurements with the clock jitter is approximately Gaussian distribution,which is well coincident with the theoretical analysis.Moreover,the relatThe positioning error of accelerometers due to a clock jitter is analyzed by Monte Carlo analysis method.The simulation results reveal that the distribution of acceleration measurements with the clock jitter is approximately Gaussian distribution,which is well coincident with the theoretical analysis.Moreover,the relation between the variance of integration distance and the clock jitter is analyzed.Both the theoretical and simulation results indicate that the error of numerical double integration due to the clock jitter increases proportional to the clock jitter.When the input acceleration signal is a sine wave with a amplitude of 1g and a period of 1 s,the ratio between the integration error of numerical double integration and the clock jitter is 0.261 1 after 1 s..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1630 (2009)
Comparison of different processes in making EHD micropump electrode
YU He, ZHANG Qiang, QIAO Da-yong, and YU Jian
The fabrication and design of micro-electrodes(the key component of Electrohydrodynamic(EHD) micropump) using MEMS technology are studied in this paper.The main part of the EHD micropump is a planar electrode array composed of electrode pairs made of the emitter and the collector.The electrohydrodynamic (EHD) pump usesThe fabrication and design of micro-electrodes(the key component of Electrohydrodynamic(EHD) micropump) using MEMS technology are studied in this paper.The main part of the EHD micropump is a planar electrode array composed of electrode pairs made of the emitter and the collector.The electrohydrodynamic (EHD) pump uses the interaction between an electric field and electric charges,dipoles or particles embedded in a dielectric fluid to drive the fluid.The major key-controlling variables including the selection of electrode materials,diversification of electrode geometrical design,comparison of different fabrication processes,electroplating and kit-off process are analyzed systematically.The experimental results show that noble metals have good performance of resistance for corrosion electrochemical processes,and the electrode with sharp geometry can improve the performance of micropump.It also shows that kit-off process is better than electroplating process in electrode quality..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1635 (2009)
Design of contactless conductivity detecting circuit for electrophoresis chip
LIU Hai-tao, WEN Zhi-yu, XU Yi, LIANG Jing, and YANG Yu-fa
On the basis of the structure of a pole conductivity detector for an integrated low voltage electrophoresis chip,a contactless conductivity detecting circuit is designed according to the working principle of high frequency contactless conductivity detecting,which consists of an AC inspiriting signal generator,a I-V conOn the basis of the structure of a pole conductivity detector for an integrated low voltage electrophoresis chip,a contactless conductivity detecting circuit is designed according to the working principle of high frequency contactless conductivity detecting,which consists of an AC inspiriting signal generator,a I-V convertor,a multiplicator,a low-pass filter and a differential amplifier.By using less devices and simple structures to realize powerful detecting,the circuit resolves the problem difficult to detect the very weak signals of low voltage electrophoresis chips. Finally,a test is applied to a electrophoresis chip to detect the contactless conductance signals of different concentrations of K+ by using the detecting circuit with an AC inspiriting signal of 10 V and the inspiriting frequencies of 450 kHz and 1 MHz.The experimental results show that the circuit can distinguish the lowest concentration of 10-9,and can reach the high linearity and resolution power in the ranges of 10-9-10-5.For its detecting functions,this circuit is able to used in other conductivity detecting fields..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1640 (2009)
Realization of interface between MEMS process simulation and finite element software
JIAN Fu-jian, and LI Wei-hua
The process simulation for Micro-electric-mechanic Systems(MEMS) can be used in predicting the actual structure of a MEMS before processing,which contributes to understand processing properties,shorten design periods and to reduce production costs.Because the current simulation software for MEMS analysis can not be comThe process simulation for Micro-electric-mechanic Systems(MEMS) can be used in predicting the actual structure of a MEMS before processing,which contributes to understand processing properties,shorten design periods and to reduce production costs.Because the current simulation software for MEMS analysis can not be combined with a finite element software,this paper presents a interface named as ANDYD Parametric Design Language(APDL) to link the process simulation software and the finite element software.By proposed APDL,the results from MEMS process simulation are imported into the finite element software to establish a model,then it is used to analyze on mechanical,electrical and thermal parameters.Moreover,the largest circle algorithm is introduced the software to implement the model reconstruction for the process simulation in the finite element software after analysis on several kinds of boundary contour extraction methods,which completes an seamless linking from the process simulation to the finite element analysis(FEA).Experimental results prove that proposed interface design is conductive to the systematization of MEMS CAD technologies..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1646 (2009)
Design of fluxgate sensor interface ASIC
DONG Chang-chun, CHEN Wei-ping, and ZHOU Zhi-ping
A fluxgate sensor interface,Application Specific Intergrate Circuits(ASIC) based on the Complementary Metal Oxide Semiconductor(CMOS),is designed and manufactured by a 0.6 μm DPDM P-sub brief process and the second-harmonic detection of output voltage.This kind of integrated interface circuit of the fluxgate can decreaA fluxgate sensor interface,Application Specific Intergrate Circuits(ASIC) based on the Complementary Metal Oxide Semiconductor(CMOS),is designed and manufactured by a 0.6 μm DPDM P-sub brief process and the second-harmonic detection of output voltage.This kind of integrated interface circuit of the fluxgate can decrease the dimension of traditional discrete components,and can reduce the power consumption to meet the requirements for miniaturization and low-power consumption in aviation and military domains.In consideration of the structure and specification of the fluxgate sensor,the excitation and pick-up circuits with the size of 2 mm×2 mm for the sensor are proposed,and the functions and parameters of all parts of the circuits are verified by a HSPICE.The experiment results of the circuit system with the fluxgate sensor show that the circuit can offer a sensitivity of 16.5 μV/nT and the linear ranges of ±90 μT.With a voltage supply of 5 V,the total power consumption of the circuit is as low as 35 mW..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1651 (2009)
Terminating type MEMS microwave power sensor based on MMIC
XU Ying-lin, LIAO Xiao-ping, and TIAN Tao
On the basis of the Seebeck effect,a terminating type MEMS microwave power sensor fully compatible with the GaAs Monolithic Microwave Integrated Circuits(MMIC) process is presented.A thermocoupler in the microwave power sensor is used to detect the temperature difference and to generate a DC voltage proportional to theOn the basis of the Seebeck effect,a terminating type MEMS microwave power sensor fully compatible with the GaAs Monolithic Microwave Integrated Circuits(MMIC) process is presented.A thermocoupler in the microwave power sensor is used to detect the temperature difference and to generate a DC voltage proportional to the microwave power.Then,a series of GaAs/Au thermocouples make up a thermopile.The sensor based on a simple principle converts the electric power into heat and the DC voltage produced by the heat is indirectly measured,so that the output microwave power can be obtained.Moreover,in order to minimize the thermal and electromagnetic losses,the bulk GaAs located beneath the device is removed through micromachining.As a result,the sensitivity of the sensor is improved.Tested results show that the HFSS simulation of S11 is less than -22 dB when the sensor measures the microwave power from -20 dBm to +20 dBm.The sensor sensitivity is higher than 0.15 mV/mW at 20 GHz,and the input return loss is less than -26 dB over the entire frequency ranges..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1656 (2009)
Guidance and implement of micro system based on GPS
WEI Qiang, WANG Xiao-hao, ZHOU Zhao-ying, and XIONG Shen-su
Micro Air Vehicles(MAV) are characterized by their small sizes,low powers and load ability,so it is difficult to obtain the full state measurements in real time and short of a full control degree.In order to solve the problems of autonomous fight control and stability,this paper presents a guidance algorithm for the reMicro Air Vehicles(MAV) are characterized by their small sizes,low powers and load ability,so it is difficult to obtain the full state measurements in real time and short of a full control degree.In order to solve the problems of autonomous fight control and stability,this paper presents a guidance algorithm for the relative miniature GPS-based navigation system of an electrically MAV. One standard geometric method for solving autonomous flight is adopted to derive a class of algorithm based on the heading angle error and yawing distance error and the MEMS sensors are used to design a flight control system.Simulation and practical experiments show that the guidance algorithm used in the MAVs is effective with different PID controlling parameters,which can obtain a yawing distance error less than 30 m.The TH680 equipped with the GPS-based autonomous flight control system loading the designed geometric algorithms has been successfully tested in a flight,and the yawing distance error is less than 30 m in a 2 level wind..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1660 (2009)
Segmentation for extended target in complex backgrounds based on clustering and fractal
ZHANG Kun-hua, and YANG Xuan
A new segmentation algorithm which was divided into two steps was proposed for an extended target in complex backgrounds by utilizing the K-means clustering and fractal theory.Firstly,the K-means clustering algorithm was improved by using the rough set theory to determine initial cluster centroids.On the basis of K-meaA new segmentation algorithm which was divided into two steps was proposed for an extended target in complex backgrounds by utilizing the K-means clustering and fractal theory.Firstly,the K-means clustering algorithm was improved by using the rough set theory to determine initial cluster centroids.On the basis of K-means clustering segmentation and region connection,the edges of the target and backgrounds were extracted accurately and intactly.After boundary tracking,the potential target regions were detected according to the characteristics of the extended target.Secondly,by giving the function of a fractal dimension changing with the scale,the natural backgrounds in potential target regions were removed by the fractal scale invariance.Then,the background conglutination was eliminated by a mathematical morphology method.The experimental results indicate that the algorithm can segment the extended target in complex backgrounds correctly and reliably,and the segmented target reserves a good contour..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1665 (2009)
Precise simulation of star spots and centroid calculation based on Gaussian distribution
WANG Hai-yong, FEI Zheng-hong, and WANG Xin-long
In order to improve the precision of the simulation system in a star sensor,this paper presents a gray pervasion method based on a Gaussian law for precisely simulating star spots and a Gaussian centroid extraction algorithm.The gray vaiues of simulating star image pixels are evaluated according to the 2D Gaussian distIn order to improve the precision of the simulation system in a star sensor,this paper presents a gray pervasion method based on a Gaussian law for precisely simulating star spots and a Gaussian centroid extraction algorithm.The gray vaiues of simulating star image pixels are evaluated according to the 2D Gaussian distribution law and the mapping coordinates instead of the central pixel round coordinates are taken as the symmetric center,so as gray pervasion phenomenon caused by defocusing and aberration from an actual star spot can be simulated precisely.The new Gaussian centroid extracting sub-pixel positioning method consists of two steps.One is rough pixel-level positioning and the other is fine deviation positioning.A piecewise defined synthesized function is constituted based on Gaussian law to realize the sub-pixel fine deviation positioning.Under the simulating condition of image Gaussian noise in N(0,1.22) and the whole deviation interval of [-0.5,0.5) pixel,the Gaussian centroid positioning precision is 0.007 pixel,which is far less than 0.041 pixel from the gray-weighted centroid method and 0.026 pixel from the square-gray weighted centroid method.After disposing the simulation star map,the conclusions show that the Gaussian gray pervasion method for simulation star spots is rational and accurate,and Gaussian centroid extracting method has a higher precision than those of traditional gray-weighted centroid methods..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1672 (2009)
Optimal test suite generation methods based on fusion of environment and state parameters
WANG Jun-jie, SHEN Xiang-heng, ZHANG Bo, QUAN Wei, and CHEN Lei
With the aim to improve the efficiency and the coverage rate of the software testing,the generation methods of the test cases are researched.On the basis of the test methods such as equivalence classifications,this paper presents a technique to divide the interface parameters into two types,environment parameters and sWith the aim to improve the efficiency and the coverage rate of the software testing,the generation methods of the test cases are researched.On the basis of the test methods such as equivalence classifications,this paper presents a technique to divide the interface parameters into two types,environment parameters and state parameters.Then,the effect of two different parameters with different characters on the generation of testing cases is analyzed and their algorithm models are established respectively.According to all of these,the reducible test cases are generated by fusing their functions in practice.Experimental results show that the test cases generated by the proposed method is one fifth as high as those of traditional generation methods at the same coverage rate,which reaches the purpose of covering more test demands with fewer test cases..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1678 (2009)
Robust forensics for image regional duplication and forgery based on DWT and Zernike moment
WANG Jun-wen, LIU Guang-jie, ZHANG-Zhan, DAI Yue-wei, and WANG Zhi-quan
Most of the existing detection algorithms for testing the region duplication and forgery are not robust in the post region duplication image process,and have high time complexities.In this paper,an efficient and robust algorithm is presented for detecting and localizing this type of malicious forgery.After reducing theMost of the existing detection algorithms for testing the region duplication and forgery are not robust in the post region duplication image process,and have high time complexities.In this paper,an efficient and robust algorithm is presented for detecting and localizing this type of malicious forgery.After reducing the image dimension by Discrete Wavelet Transform(DWT),the Zernike moment is applied to the fixed sized overlapping blocks of a low-frequency image in the wavelet sub-band,and the eigenvectors are lexicographically sorted.Then,similar eigenvectors are matched by a certain threshold.Finally,the area threshold is proposed to remove the wrong similar blocks,and the mathematical morphology operations are performed to localize the forgery part.Experimental results show that proposed method is robust and not only can successfully detect this type of forgery for images subjected to post region duplication processing in various forms,but also can search block spaces in only the 1/4 image,which improves the calculation efficiency of algorithm.The method suits to the robust forensics for image contents..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1686 (2009)
Signal phase error compensation of Moiré fringe
Lü Meng-jun, Guo Qi, and L Yin-xiao
In order to eliminate the tangent subdivision error caused by nonorthogonal Moiré fringe signals,a new algorithm is presented to compensate the real-time phase laggard error.After analyzing the effect of the phase nonorthogonality on subdivision precision,the cosine signal phase error is worked out based on sampliIn order to eliminate the tangent subdivision error caused by nonorthogonal Moiré fringe signals,a new algorithm is presented to compensate the real-time phase laggard error.After analyzing the effect of the phase nonorthogonality on subdivision precision,the cosine signal phase error is worked out based on sampling the signal with zero value well and the actual phase formula is determined clearly.According to the polarity and amplitude of the signal with laggard phases,the shorter periodic signals are compensated in a certain section phase respectively and the factors influencing the compensation precision are analyzed.Experimental data indicate that this algorithm can compensate the phase error perfectly and can depress the effect of the nonorthogonal signals on the subdivision precision.Obtained results show that the subdivision error by using the proposed method reduces to 10 percent of the original error and the subdivision and location precisions are improved greatly..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1694 (2009)
Three-dimensional digital imaging based on microlens array
ZHANG Jian, XIN Yue, LIU Wei-qi, LI Gui-ju... and LIU Hua|Show fewer author(s)
A new reconstruction algorithm was proposed based on multi-perspective imaging characteristics of a microlens array and geometrical optical principles.By proposed algorithm,an original object was reconstructed with the elemental image array captured by a CCD camera.In compasison with traditional method using optical syA new reconstruction algorithm was proposed based on multi-perspective imaging characteristics of a microlens array and geometrical optical principles.By proposed algorithm,an original object was reconstructed with the elemental image array captured by a CCD camera.In compasison with traditional method using optical systems,this algorithm was not affected by the stray light and diffraction effect in the process of reconstruction,and has advantages of real-time and sharp quality.An experimental platform based on a three-dimensional digital imaging system with a microlens array was setup to reconstruct the elemental image array of a die captured in experiment,a volumetrically original image was reconstructed through this algorithm successfully.It is proved that the algorithm is feasible and valid both theoretically and experimentally.Finally,several factors affecting the imaging quality in the experiment are analyzed..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1701 (2009)
Target tracking using distributed Unscented particle filter in sensor network
XIAO Yan-guo, WEI Jian-ming, XING Tao, Yin Ze-jie, and LIU Hai-tao
A new distributed target tracking algorithm,Distributed Unscented Particle Filter(DUPF),is proposed to improve the usual distributed particle filter methods with more particles and more information communication between the two nodes.In consideration of the enengy-limited sensor network and the imperfect communication,A new distributed target tracking algorithm,Distributed Unscented Particle Filter(DUPF),is proposed to improve the usual distributed particle filter methods with more particles and more information communication between the two nodes.In consideration of the enengy-limited sensor network and the imperfect communication,a few node calculations are used in this thesis to get a better tracking results for manoeuvering targets.The Unscented Kalman Filter(UKF) in new DUPF is used to improve the particle filter to generate the proposed particle distribution,so the on line tracking for a target can be realized by the DUPF.A simulation experiment indicates that the number of particles needed by DUPF is only 25% that of the common distributed particle filter,which shows that DUPF has gotten more accurate tracking results with less communication nodes and energy cosumption..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1707 (2009)
Implementation of automatic target recognition by imaging Ladar in complex scenes
MA Chao-jie, YANG Hua, LI Xiao-xia, WU Dan, and HUANG Chao-chao
A novel Automatic Target Recognition(ATR) algorithm based on imaging Laser Radar(Ladar) is proposed to solve the target recognition difficulty caused by a tree sheltering,and the algorithms such as data classification,data mosaic,target pose adjustment and target recognition based on a height histogram are studied.The A novel Automatic Target Recognition(ATR) algorithm based on imaging Laser Radar(Ladar) is proposed to solve the target recognition difficulty caused by a tree sheltering,and the algorithms such as data classification,data mosaic,target pose adjustment and target recognition based on a height histogram are studied.The scene data are classified into several parts (ground,targets and trees) by using an image processing technique,and the translation matrixes among different views are calculated from coarse to fine according to their inherent attributions.Then,the data from different views are integrated together.According to its normal directions,each target pose is adjusted to the top view,and its height histogram can be calculated.Finally,the target is recognized by matching the target height histogram with the saved model height histograms.Experimental results indicate that the extracted target part is more than 90% of the whole target area and the recognition ratio is more than 99%,which satisfies the ATR requirements in stabilization,higher recognition ratios and strong anti-jamming..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1714 (2009)
Watermark algorithm using lifting-scheme wavelet transform
FAN Ya-chun, ZHOU Ming-quan, WANG Xing-ce, and LIU Xin-yu
An improved algorithm based on a lifting scheme wavelet transform is proposed to protect the copyright of a cultural relic image during Web sharing.The YCbCr color space is used to ensure the lightness and color sensitivity in a visual system.Then,the Daubechies9/7 biorthogonal wavelet is introduced to transform the imAn improved algorithm based on a lifting scheme wavelet transform is proposed to protect the copyright of a cultural relic image during Web sharing.The YCbCr color space is used to ensure the lightness and color sensitivity in a visual system.Then,the Daubechies9/7 biorthogonal wavelet is introduced to transform the image into a frequency domain and to hide watermark information to improve the anti-attacked capability.Meanwhile,a lifting scheme is used to enhance the stability of the algorithm.Finally,in order to increase algorithm's robustness and security,a new embedding method is presented to embed the intermediate and high frequency watermark information into image's high frequency coefficients,and the embedded position is switched dynamically in depending on the neighborhood coefficients.Experimental results indicate that the cultural relic image show a better visual quality after embedding watermark,and the Peak Signal Noise Ratio(PSNR) of the watermarked image is 51.602 4,which is better than that of other algorithms.Compared with LSB and DCT algorithms,the proposed algorithm has good performance in the anti-attack and lossy compression and is suitable for the fields which request high security such as digital museums..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1722 (2009)
Analysis of relationship between finger width and recognition rate
YUAN Wei-qi, ZHU Chun-yan, and KE Li
The finger width is one of the effective features in the hand shape recognition,and the selected measuring points effect on the accuracy and recognition time.This paper researches the relationship among the selected points,recognition rates and matching time to estimate the selected points in different fingers accordinThe finger width is one of the effective features in the hand shape recognition,and the selected measuring points effect on the accuracy and recognition time.This paper researches the relationship among the selected points,recognition rates and matching time to estimate the selected points in different fingers according to different required recognition rates.Obtained results prove that the recognition rate is more than 90% under the conditions of accurate localization and selected points more than 3 in each finger.An automatic recognition algorithm is proposed,in which the curvature is used to localize feature points,then it used to calculate the absolute widths of fingers.After the eigenvectors are formed by the relative widths between two absolute widths,the Euripides distance between the two eigenvectors is computed to implement the feature recognition.Experiments show that feature values can be acquired to distinguish the human's identity when 6 points of each finger are selected,and the recognition rate can reach 94.03%.Experiment results present the two relationship curves of the number of points vs the matching time and the number of points vs the recognition rate..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1730 (2009)
Realization of image restoration by improved Paik′s Boltzmann machine
ZHANG Yu-dong, and WU Le-nan
An improved Paik′s Boltzmann machine was presented to optimize the traditional Boltzmann method that suffers from not only being trapped into a local extreme but also a slow convergence.By proposed the method,the Paik′s algorithm is integrated into the Boltzmann machine to restored images.Then,serial models are extendeAn improved Paik′s Boltzmann machine was presented to optimize the traditional Boltzmann method that suffers from not only being trapped into a local extreme but also a slow convergence.By proposed the method,the Paik′s algorithm is integrated into the Boltzmann machine to restored images.Then,serial models are extended to parallel models to fasten the convergence speed and a subunit step is adopted to increase calculation precision.Finally a step adaptive method is used to trade off the contradiction of convergence precision and convergence velocity.Moreover,each improvement for the origonal algorithm is expatiated by theoritical validation,convergence analysis,and discussions of residual variations.Experiments demonstrate that the proposed method can be converged to the global minimum,and the Peak Signal Noise Ratio (PSNR) of the restored image is 0.5-0.8 dB higher than that of the improved Boltzmann method proposed by Bellouquid,while the consumed time is only 1/3 that of the latter.These results show that the proposed method is effective and valid for image restorations..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1737 (2009)
Stereo correspondence using multi-stage dynamic programming
GUO Yong-cai, WEI Peng-yu, and GAO Chao
Dynamic programming is one of the oldest but still popular methods for stereo correspondence.Because the traditional stereo matching based on the dynamic programming has the well-known horizontal “streaking” effect for skiping the vertical edges,a stereo correspondence using the multi-stage dynamic programming is propoDynamic programming is one of the oldest but still popular methods for stereo correspondence.Because the traditional stereo matching based on the dynamic programming has the well-known horizontal “streaking” effect for skiping the vertical edges,a stereo correspondence using the multi-stage dynamic programming is proposed to eliminate this effect in this paper.Firstly,the initial disparity space is constructed,and the down and up dynamic programming processes are operated across the epipolar lines.Then,the initial disparity space is optimized by the combined results above.Finally,based on the new disparity space,the forward and backward dynamic programming processes are implemented along the epipolar lines,and the disparities are obtained by minimizing the combined results of the dynamic programming along and across the epipolar lines.This algorithm is evaluated on the benchmark Middlebury database.The experimental results show that the “streaking” effect is suppressed and the general error matching rates have decreased by 28.60% and 40.42% respectively compared with that of the traditional dynamic programming algorithm and the scan-line optimization algorithm,which can offer a good trade off in terms of the accuracy.It is demonstrated that the proposed algorithm is more efficient..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1745 (2009)
Detection of region-of-interest by morphological Haar wavelet method
SONG Yan-xing, YUAN Feng, DING Zhen-liang, and SUN Chun-feng
The Auto Target Recognition (ATR) has been used to solve the problem that the huge data flows provided by a high speed image acquistion system are not easily transferred and stored,in which the key is how to find the Region-of-interest (ROI) of a target quickly and exactly.To detect the ROI of the target,a morphology HThe Auto Target Recognition (ATR) has been used to solve the problem that the huge data flows provided by a high speed image acquistion system are not easily transferred and stored,in which the key is how to find the Region-of-interest (ROI) of a target quickly and exactly.To detect the ROI of the target,a morphology Haar wavelet method and a mathematic morphology are combined to use in the ROI detection and a new target ROI detection operator is designed. An image is decomposed with morphology Haar wavelet,then the new ROI detection operator is used in the field of scale signal decomposed by morphology Haar wavelet to find the ROI of target.The simulation results indicate that the highest detection ratio of the ROI can reach 1.000 0 and the lowest false alarm ratio of the ROI only is 0.001 2.Moreover,the time consumption is only 10-1s for a image with a pixel level of 102×102.In comparison with traditional algorithmns,this method can find the ROI of the target effectively and can save the time consumption and hardware resource..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1752 (2009)
Implementation of scene matching based on rotation invariant keylines
ZHANG Ye, QU Hong-song, and WANG Yan-jie
In order to provide a robust scene matching algorithm with the scale and rotation invariance and less influence by different illumination under complex conditions,this paper researches scene matching techniques based on key lines.Inspired by the Human Visual System (HVS),a new scene matching method based on key lines iIn order to provide a robust scene matching algorithm with the scale and rotation invariance and less influence by different illumination under complex conditions,this paper researches scene matching techniques based on key lines.Inspired by the Human Visual System (HVS),a new scene matching method based on key lines is put forward by using a set of filters that are the same processing models as the human cortex filter.The mathod uses the vectors to describe key lines to implement the metching between the two images and is characterized by less numbers of key line and great information as compared with that of a point matching method.It introduces the extraction,expression and matching lines and gives the simulation results and matching properties.Experiment results show that the proposed method works well for the condition of rotating and scaling,and can offer the precision of scene matching of 1 pixel,which meets the requirements of high stability and good robust for complex background scene matching..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1759 (2009)
Target localization in wireless sensor networks based on LSSVR
LIU Gui-xiong, ZHANG Xiao-ping, and ZHOU Song-bin
In consideration of the effect of ranging errors of the RSSI method on the target localization accuracy in a Wireless Sensor Networks (WSN),a mathematical model of target localization based on Least Square Support Vector Regression (LSSVR) is established according to the double mapping between the target's coordinaIn consideration of the effect of ranging errors of the RSSI method on the target localization accuracy in a Wireless Sensor Networks (WSN),a mathematical model of target localization based on Least Square Support Vector Regression (LSSVR) is established according to the double mapping between the target's coordinate and the distance vector measured from the target to sensor nodes.Furthermore,the target localization method based on LSSVR in the WSN,TL-LSSVR,is proposed.According to TL-LSSVR,the training samples are formed in accordance with the virtual target coordinate and the distance vector between the virtual target and the sensor nodes,and then the training sample sets are obtained by selecting learning areas and grid sampling.Moreover,the localization model can be trained using LSSVR and the target can be located by inputting the distance vector between the target and the sensor nodes into a localization model.The experiments of target localization in the WSN under different numbers and distributions of sensor nodes are performed.Experimental results show that when sensor node distributes randomly,the target localization errors using the TL-LSSVR are reduced by 21.0%-43.1% compared with that of a least square estimation,and when sensor node distributes uniformly,the target localization errors are reduced by 26.5%-48.7%,which indicates that the target localization errors are reduced evidently,and the accuracy of target localization is improved..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1766 (2009)
Image denoising using non-Gaussian bivariate model based on non-aliasing Curvelet transform
YAN He, PAN Ying-jun, LIU Jia-ling, and ZHAO Ming-fu
A new image denoising method using a non-Gaussian bivariate model in a Complex Curvelet Transform(CCT) domain is presented.For avoiding the shift-variance and under-sampling during the 1D inverse Fourier transform in the traditional Curvelet transform ,a new Curvelet transform,Complex Curvelet Transform(CCT),is proposeA new image denoising method using a non-Gaussian bivariate model in a Complex Curvelet Transform(CCT) domain is presented.For avoiding the shift-variance and under-sampling during the 1D inverse Fourier transform in the traditional Curvelet transform ,a new Curvelet transform,Complex Curvelet Transform(CCT),is proposed by adopting the complex wavelet transform and reformative Radon transform to replace the traditional wavelet transform and the old Radon transform respectively,which provides a non-aliasing property for the proposed method.Because the inter-scale correlation of a signal coefficient is stronger than those of noise coefficients,the non-Gaussian bivariate model is used for capturing inter-scale correlation of the signal coefficient and for obtaining the denoised coefficient from the noisy image decomposition by a Bayesian MAP estimator.Experimental results show that the Peak Signel Noise Rotio(PSNR) of the proposed algorithm is averagely higher about 2.9 dB and 1.5 dB than those of the traditional Curvelet transform denoising method and Curvelet domain HMT denoising method respectively at all noise levels.The proposed method avoids “scratching” and “embedded blemishes” phenomena in the reconstructed image,and achieves an excellent balance between suppressing noises effectively and preserving image details and edges as many as possible..
Optics and Precision Engineering
- Publication Date: Sep. 20, 2021
- Vol. 17, Issue 7, 1774 (2009)
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