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Issue 5 ， 2006
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Optimization design for all-solid-sate 355 nm continuous-wave ultraviolet laser
Abstract：A laser-diode (LD) pumped Nd:YVO4 all-solid-state 355 nm continuous-wave (cw) ultraviolet laser with intracavity frequency tripling and efficient output was achieved by optimization design. By considering influence of the thermal lens effect of the Nd:YVO4 crystal, mode matching, phase matching et al on laser output power,a plate-concave cavity was designed finely. In cavity, the KTP crystal was used for second harmonic generation (SHG) of the fundamental 1 064 nm to generate 532 nm radiation, and the LBO crystal was used as a sum frequency (SM) of the 1064 nm radiation and the 532 nm radiation to generate 355 nm radiation. The cw 355 nm radiation of 6.4 mW is obtained with the pump power of 3 W. In comparison with the fold-cavity, the linear cavity has many advantages of more compact, easier for adjusting, and higher output power.Keywords：continuous-wave ultraviolet laser;all-solid-state laser;355 nm laser;LD-pumping;sum-frequency- 66
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Published：2020-08-12 -
An adjusting method of plane-concave laser resonator based on Gaussian beam
Abstract：A adjusting method of optically plane-concave laser resonator based on Gaussian beam is presented when the pump source is absent. A parallel incidence Gaussian beam through a lens system is used to hit on the concave mirror and the plane mirror of the plane-concave resonator. The importing of the lens system is to improve the adjusting precision of the beams reflected from the concave and the plane mirror by causing one beam size similar to another, because it can not get similar beam size reflected when a parallel incidence Gaussian beam is directly hit on the concave and the plane mirrors of the resonator. In the experiment, a He-Ne laser with waist of 0.6 mm is utilized to adjusting a plane-concave resonator with a concave mirror in a radius of 50 mm at measuring distance of 889 mm. The beam sizes reflected from the concave mirror and the plane mirror are 48 mm and 5.1 mm,respectively. The angle adjusting precision of the plane-concave resonator is 3.18'. TEM00 mode can be abtained by pumping the resonator module that has been adjusted with a LD. The results show that the adjusting method is simple and flexible, and can be used to separate the laser resonator and the pump source module.Keywords：Gauss beam;optical adjusting;plane-concave laser resonator- 61
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Published：2020-08-12 -
Design and stability analysis of high frequency LD's driving circuit
Abstract：On the basis of analyzing the main factors effecting on the LD stability, a 1 kHz repeating frequency LD driving power supply with real-time feedback,closed-loop control and pulse current stabilization was designed. By restraining the surge and the ripple, adopting the delay-time and soft-startup circuit, this system improves the security of both the LD component and power supply. With the thermo-electronic cooler and PC that can detect the circuit real-time, the temperature of the LD can be kept accurately. Primarily, the LD laser output power is 150 W, the stability of the constant temperature power is 0.2 ℃, and the laser line width is about 6 GHz in the experiment.Keywords：semiconductor laser;driving design;LD power supply;stability- 59
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Published：2020-08-12 -
Fabrication and test of large scale light-weight SiC miror
Abstract：The large scale light-weight silicon carbide(SiC) mirror blanks at 620 mm and 700 mm×300 mm were prepared with gel-casting method. After drying, burning out the organic elements, infiltrating carbon and reaction-sintering, the reaction-bonded SiC (RB-SiC) mirrors were fabricated. The results of ground mirrors show that the structure of RB-SiC is full solid, and the mechanical and thermal properties of RB-SiC are excellent in bending strength of 350 MPa, fracture toughness of 4.1 MPa·m1/2 and coefficient of thermal expansion (CET) of 2.67×10－6/K. The surface roughness (RMS) of the polished mirror is better than 3 nm, it is a fine material for the space-borne large scale light-weight mirror.Keywords：Gel-casting;light-weight mirror;reaction-bonded SiC- 68
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Published：2020-08-12 -
Experimental and theoretical study on laser cleaning Al2O3 particle on silicon wafer surface
Abstract：The laser cleaning of Al2O3 particles which are the main component of the silicon wafer lap-polishing solution commonly used in industry nowadays was studied by experiments combined with theoretical analysis. The simple heat-conduction model was built and the temperature field on silicon wafer surface during laser cleaning was simulated using the finite element method. The adhesion force between the particle and the substrate and cleaning force acting on the particles were calculated, and the theoretical threshold of laser cleaning 1 μm Al2O3 is 60mJ·cm-2. Under the guidance of the mechanism analysis, a serial of laser dry cleaning experiments were carried out to study the dependence of laser cleaning efficiency on laser fluence, numbers of pulse, and laser beam incidence angle on silicon wafer surface using 248 nm, 30 ns, KrF excimer laser, Which confirmed the clean model as well as the effect of the field enhancement on laser cleaning.Keywords：laser cleaning;silicon wafer;cleaning efficiency;Al2O3 particle- 56
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Published：2020-08-12 -
Chemical sensor based on a fiber Bragg grating
Abstract：Bragg wavelength sensitivity to the refractive index of the ambient media can be realized by etching out the cladding of fiber Bragg grating. A fiber Bragg grating with the diameter of 6 μm is abtained through hydrofluoric (HF) acid etching. Bragg wavelength sensitivity to chemical solutions is experimentally investigated. With an optical spectrum analyzer to detect the wavelength shift, the concentration resolutions of propylene glycol solutions are 0.7% and 0.32% at low and high concentrations, respectively. For sugar solutions, concentration resolutions are 0.55% and 0.1% respectively. In addition, the concentration resolutions can be improved an order of magnitude with wavelength interrogation module of 1 pm resolution.Keywords：fiber Bragg grating;chemical sensor;biosensor;refractive index- 73
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Published：2020-08-12 -
Influence of UV radiation on absorptivity of cavity of absolute radiometer
Abstract：To investigate the influence of the solar UV radiation on the absorptivity of the cavity of absolute radiometer of solar irradiance monitor on satellites, a simulated experiment is carried out in laboratory. A hydragyrum lamp with irradiance equaled to the total solar UV irradiance is used to irradiate the cavities. The change of the absorptivity of the cavity with the UV radiation quantum is measured by an integrating measurement instrument on the reflectance of black cavity within a full hemisphere (include the entrance of the Ulbrichtsphere), which can measure the absorbance of the mirror reflection and the diffused reflection in a high precision simultaneously. The results show that the UV radiation received by the solar irradiance monitor on FY-3 satellite will cause the absorptivity degradation of the cavity of absolute radiometers of 0.002% per year, and the most is 0.003% per year. The result is consistent with the changing instance of other absolute radiometers for measuring solar irradiance on other satellites basiclly. The experiment indicates that the UV irradiance has influence on the absorptivity of the cavity of absolute radiometer on satellites. The result also might supply essential reference for optimization, experiment, measurement and calibration of the solar irradiance monitor on satellites in future.Keywords：solar irradiance monitor;absolute radiometer;cavity;UV radiation;absorptivity- 38
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Published：2020-08-12 -
High-speed photopolarimeter based on a linear neural network
Abstract：A novel high-speed photopolarimeter is presented,in which a incident light is divided into multiple beams by a special metallic grating that can generate both reflective diffraction and transmission diffraction. The light fluxes of the four 1st order diffracted beams are linearly converted into four electrical signals by a photoelectric conversion circuit. A multilayer linear neural network model is set up whose inputs are the electrical signals, and outputs are the Stokes parameters of the incident light. The mapping relationship between the electrical signals and the Stokes parameters can be determined by training the neural network. After the electrical signals are measured, the unknown Stokes parameters of the incident light can be calculated via a trained neural network. The testing results show that the mean deviation of the measured and theoretical Stokes parameters is less than 2% at λ=632.8 nm. This instrument is compact,easy to install and characterized by fast response, high precision and damaging-free in working states.Keywords：photopolarimeter;neural network;division-of-amplitude;data processing- 60
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Published：2020-08-12 -
Thermal effect of YVO4-Nd:YVO4 composite laser crystals
Abstract：Through characteristic analysis of composite laser crystal, a thermal analysis model of rectangle composite crystal was introduced. In the thermal model,the composite crystal was characterized by axially symmetrical heating,fixed boundary temperature and coupled pump laser having Gaussian distribution. Based on the heat conductive equation and its boundary, the analytical solutions of interior temperature field and thermal deformation of YVO4-Nd:YVO4 composite crystal were obtained. The result shows that when the end-pumped power of diode laser is 20 W and the diameter of pump spot is 0.2 mm, the maximal temperature rise of YVO4-Nd:YVO4 composite crystal(the length of YVO4 crystal is 2 mm , the length of Nd:YVO4 crystal is 6 mm and the neodymium doped concentration in Nd:YVO4 crystal is 0.5 %) is 324.5℃, and thermal distortion on pump-face of composite crystal is 3.61 mm. Under the same pumped conditions, the maximal temperature rise is decreased by 23.4% using the composite crystal instead of Nd∶YVO4 crystal. This means it can reduce thermal effect influence of laser crystal and improve laser characteristics and performance, and also can solve nonuniform temperature rise and thermal fracture problems of laser crystal by high power diode laser end-pumped.Keywords：diode laser;YVO4-Nd:YVO4 composite crystal;analytical solution;thermal effect- 36
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Published：2020-08-12 -
Realization of electric control of laser direct writing mesh on concave spherical substrate
Abstract：By using a concentrical configuration, a control arithmetic of adjusting the angular velocity and a mesh pattern of periodical latitude lines intersecting periodical latitude lines perpendicularly to ensure the writing spot scanning at different angular velocities in different latitudes and to keep the linear velocity and exposure dose invariable all the time in the laser direct writing system the invariable exposure dose laser direct writing mesh on the spherical substrate was realized. The key parameters such as the periods of gridding, the angular velocity and the arc length of the latitude lines were analyzed and the control program was designed. Several group experiments of laser direct writing mesh on the concave spherical substrate made of common glass with 60 mm were done at periods of 450~800 μm and linear velocity of 1~20 mm/s. After development and fixation, the error of gridding periods measured by micron level reading-microscope is within ±3%. Line width measured by AFM is less than 5 μm. The experiments results indicate that the concentrical configuration and control of steady light and angular velocity adjusting have ensured the exposure dose invariable, which make laser direct writing lines on the spherical substrate have good uniformity, steep and straight side walls parallel to each other for satisfying the design requirements.Keywords：concave spherical substrate;laser direct writing;mesh;PMAC- 37
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Published：2020-08-12 -
Study on magneto-optical /eddy current imaging system for real-time testing
Abstract：A magneto-optic/eddy current imaging system is used to test the defects at the surface or the subsurface of the metal samples in this paper. Excited by alternating current signals, alternating current magneto field is made from the excitation coil, transient eddy current is induced at the surface and subsurface of the metal sample, and the eddy current magnetic field can influence the induced magnetic field of the excitation coil. If there are some defects in the sample, they will vary the distribution of eddy current field, and then change the whole magnetic field. The polarization of the light will have a deflection angle when the light penetrates the optical rotation crystal film. Meantime, a magnetic-optic sensor placed parallelly to the sample surface can convert this change into optical intensity change. Finally the optical intensity change is received with CCD to realize visual nondestructive testing. The experimental results show that the system is feasible and appropriate.Keywords：magneto-optic effect;eddy current;visualization;CCD;imaging system- 20
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Published：2020-08-12 -
Measuring method of visibility with optical fiber
Abstract：A measuring method to terrain atmospheric visibility with forward scattered light and transmitted light was introduced. Visibility is expressed by ratio of the intensity of the scattered light to the intensity of transmitted light. Spatial filters are utilized to limit visual angle of scattered light and transmitted light, and background interferences of measured forward scattered light and atmospheric scattered light. Using the correlation detection, atmospheric background noise is eliminated and signal-to-noise ratio for scattered light to background is enhanced. In order to keep spot of being measured light beam on the photo-detector unchanged, step index optical fiber is used in the set for improving the influence of thermal deformation on measuring error. Another characteristic is that changing in the light source and pollution to the optical elements may be ignored. The correlation coefficient between visibility from proposed method and accurate transmission method is about 98.2％.Keywords：photoelectric detection;visibility;scattering coefficient;time-spatial filtering- 45
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Published：2020-08-12 -
Impact of main discharge delay time on optoelectronic conversion efficiency in TEA CO2 laser
Abstract：This paper introduces to the experiment results of a impact of the delay time changes between spark pin UV preionization and main discharge on the optoelectronic conversion efficiency in a TEA CO2 laser. By using different inductance values in a discharge circuit, the delay time can be changed. The results indicate that the optoelectronic conversion efficiency has an optimal point when delay time is changed from 200 to 600 ns. In the same injected energy the single pulse output is increased from 24.0 to 45.6 J and optoelectronic conversion efficiency from 8％ to 15％ respectively. The highest conversion efficiency reaches 17％ after further parameters optimization.Keywords：TEA CO2 laser;preionization;delay time;conversion efficiency- 37
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Published：2020-08-12 -
Wavelength tunable erbium-doped fiber ring laser based on FBG
Abstract：Based on introducing the principle of wavelength tuning of FBG, a kind of ring Er-Doped Fiber Laser(EDFL) whose wavelength was tuned by FBG was designed. The output lasing wavelength between 1 547.7 nm and 1 556.5 nm can be tuned continuously within the temperature range from 20 to 170 ℃. The tuning linearity is up to 99.96%, the 3 dB linewidth is less than 0.05 nm and the 20 dB linewidth is less than 0.08 nm. While the side mode suppression ratio(SMSR) is more than 52 dB,the output power of EDFL is up to 21.2 mW. Experimental results show that the tunable EDFL has the advantages of wide bandwidth, high power, narrow linewidth and compatibility to fiber element.Keywords：fiber optics;Er-Doped Fiber Laser(EDFL);fiber Bragg grating;wavelength tuning- 65
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Published：2020-08-12 -
Dynamic spectral measurement of earlap on Monte-Carlo method
Abstract：With selecting earlap as the measuring spot, a multi-layer simulation model of the earlap is established. The transmittance of the earlap model and its distribution regularities under vary beam properties (beam radius, the input energy and its distribution) and model parameters are researched by Monte-Carlo method. Then from the light energy distribution, the detective area and the detective sensitivity of the detector, the input energy needed for certain signal-noise ratio is calculated. It has been proved by research results that the practicable input energy of the earlap can meet the requirement of the acquisition of the dynamic spectrum, higher measurement accuracy of the dynamic spectrum also can meet the spectrum measurement accuracy in the noninvasive measurement of blood compositions.Keywords：dynamic spectroscopy;tissue model;earlap;Monte-Carlo method- 77
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Published：2020-08-12 -
Measurement chain of influence quantities and uncertainty of radiometric calibration for imaging spectrometer
Abstract：This paper analyses the information configuration in remote sensing observation data of imaging spectrometer, including the spectral character of ground surface, instrument parameter and atmosphere transmission and also discusses on the physical process and measurement chain of radiometric calibration of imaging spectrometer. Then according to the international updated method of ISO1993(E)' Express Guide of Measurement Uncertainty, the measurement uncertainty and combined standard uncertainty of eleven influence quantities of radiometric calibration are analyzed by the special equipment such as radiation standard, light source of integral sphere, spectroradiometer and in-flight calibration sets and so on. To accomplish the radiometric calibration, the measurement process of multi-measurement chain is set up. Experimental results show that the radiometric calibration of the imaging spectrometer requires special advanced equipment and technique. To reach the absolute accuracy of 5%~8%,the uncertainty of standard spectral irradiance must be 3%~5% and the measurement uncertainty of the other influence quantity items must be limited within 1%~2%.Keywords：optical metrology and measurement;radiometric calibration;uncertainty;Precision;imaging spectrometer- 59
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Published：2020-08-12 -
Study on LD-pumped Nd:YAG laser cutter for silicon wafer
Abstract：By analysizing the theory of laser cutter, a rapid laser cutter method is given for cutting thick silicon wafer. Considering laser medium thermal lens effect and thermal focal length changing with the pumping power, using plano-convex high reflectivity mirror as the back cavity mirror to compensate the heat lens influence, utilizing the Nd∶YAG self- aperture effect also, more than 50 W average power 1.064 μm laser output is obtained with beam quality factor M2 of 4.19. Choosing suitable beam expander factor, appropriate aperture diameter of exit beam and repetition rate, when the cutting velocity is 400 mm/min, a silicon wafer of 0.75 mm thickness can be penetrated; when the cutting velocity is 100 mm/min, a silicon wafer of double-layer 0.75 mm thickness can be penetrated. Experimental results show that the cross section is fine in narrow groove and excellent repeatability precision, it is more better than that of other conventional cutting methods.Keywords：laser technology;all solid-state-laser;acoustooptical Q-modulation;laser cutter;silicon chip- 51
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Published：2020-08-12 -
Development of a new optical coordinate measuring machine in cylinder coordinates
Abstract：A new special-purpose optical coordinate measuring machine (OCMM) was developed with the cylinder coordinates to realize full aperture testing of the optical aspherics in the stage of grinding and pre-polishing. The full-aperture of optical aspherics can be measured with testing several meridians point by point. In the aspect of hardware, the system was composed mainly by an ultra-precise air-rail for the linear motion, and a graduator for the rotary motion. In the aspect of software, for analyzing the mathematical model of a system, a new algorithm for the full-aperture testing of rotational-symmetric aspherics was astablised. The testing software and data-processing software were written on the VC++6.0 and Matlab platform respectively. The system is shown the better performance in the maximum measurement range of 600 mm,the maximum sag of 25 mm and the minimum sampling step of 1 mm. After the compensation of the systematic errorsthe accuracy is higher than 1 μm in full scale. The experimental results conclude that the optical coordinate measuring machine has a good universal and can satisfy requirement in the grinding and pre-polishing process for asphere testing.Keywords：optical aspherics;contact-measurement;full-aperture test;Coordinate Measuring Machine(CMM);Zernike polynomial- 36
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Published：2020-08-12 -
Study on PdPc/H2PtCl6 hybridized organic semiconductor poison gas sensor of porous electrode flat structure
Abstract：Phthalocyanine molecular fragments were synthesized in template-based method using methyphenol, 4-nitro phthalonitrile as raw materials and N, N dimethyl formamide as solvent under the catalysis of potassium in nitrogen atmosphere. Its molecular weight was confirmed to be 243 (theoretical value is 243.34) through mass spectrography. Then through the altogether-dissolve, under the action of pentanol and DBU, molecular fragments and palladium bichloride were synthesized to form the atrovirens 4-methoxy benzoic PdPc. The measured value of absorption peak by infrared absorption spectroscopy was fundamentally uniform to the theoretical value, so that the synthetic reaction end product was determined. Further, PdPc and H2PtCl6 was dissolved in carbinol in a given proportion to synthesize for 48 h to form organic semiconductor sensitive material. According to Ohm’s law and using laser micro-machining and semiconductor techniques, a porous electrode flat structure was fabricated in the electrodes’ area increased while the space reduced, its resistance reduces more than 103 times than interdigital electrode in common use, in approach to abio-semiconductor’s conductivity. Experimental results show it is good for subsequent circuit signal's collection. Through electron scan, its mirco-appearance was observed to be continuous and porous. The air hole was 0.1~2 μm, this not only ensure its conduction but also has ventilate characteristic. Through vacuum deposition, the sensitive material was made to be a sensitive film. Under electron scan, the film's fundamental thickness was 2 μm and has 0.1~5 μm micro-ball crystal embed, uniform distributed, appeared continual mutual fuse growth. Using a static state method to measure its sensitive characteristic,the measurement indicates that the sensor appears N type semiconductor to NO2, the sensitivity is 7.45 times when the gas density is 0.010%; the sensor appears P type semiconductor to NO, the sensitivity is 0.25 times when the gas density is 0.010%; the response time is 90s. The change rule to different gases indicates its gas sensitive principle is related to the gas capability.Keywords：porous electrode;flat structure;organic semiconductor;hybridization;poison gas sensor;semiconductor sensor- 76
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Published：2020-08-12 -
Study of measurement technique on airborne photoelectric stabilized platform
Abstract：The measurement technique and method of an airborne photoelectric stabilized platform was described, and the principle and structure design of dynamic target was presented for measurement of static and dynamic parameter,especially for various parameters on platform with visible light and infrared rays system synchronously. To set up transmission measurement method datum to form general measurement technique of systemically photoelectric reconnaissance platform, the static and dynamic angles were measured. A method of using light butt to realize visible light and infrared rays measurement simultaneously was presented and a math calculating method was given also, which can obtains space coordinate of dynamic target for a real value of directional coordinate of the platform by two angles measurement and space vector calculation. The results show that proposed calculation method for dynamic target is efficiency.Keywords：airborne photoelectric stabilized platform;dynamic target;light butt;parameter measurement- 61
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Published：2020-08-12 -
Analysis of system servo following error caused by alignment error of ESG
Abstract：Two kinds of alignment errors between the gyro coordinate system and platform coordinate system were introduced when Electrostatic-Suspended Gyroscope(ESG) was used in measuring drift angle on servo turntable by Position Sensitive Detector(PSD). Then formulas for calculating the coordinate change of spot center of reflected beam on PSD caused by the alignment errors were derived, and the calculating methods of servo following errors were presented when alignment errors existed between the gyro coordinate system and platform coordinate system. According to the structure and the working condition of ESG, a group of data were chosen to calculate the servo following errors. The computational results show that the first error is two orders of magnitude larger than the second one. In order to reduce the system servo following error, the first error must be less than 4'. This conclusion plays an important theoretical guiding role in ESG designing and testing.Keywords：Electrostatic-Suspended Gyroscope(ESG);alignment error;servo following error- 54
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Published：2020-08-12 -
Study on piezoelectric jet pump
Abstract：In combination with the hydro-piezoelectric drive, bionics and water-jet thrust technology, a novel piezoelectric water-jet thrust was introduced, and the core of the thrust—piezoelectric jet pump was studied. The design, principal, process and performance of the pump jet were presented, and a prototype pump was designed and manufactured in the laboratory. Through a series of experiments and tests, It is concluded that the piezoelectric pump jet is characterized by stable performance and bucky volume of liquid flow, the optimization frequency is 1250 Hz. With the sine wave signal actuated, the maximum liquid flow rate of the pump jet is 714 ml/min when driving voltage is 190 V.Keywords：piezoelectric membrane;jet pump;water-jet thrust;PZT actuator- 27
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Published：2020-08-12 -
Establishment and analysis of cross model of flexible gyro
Abstract：Based on analysis of rigidity and drift error for a Dynamically Tuned Gyro(DTG), a cross model including an inner and an outer flexible hinges was established. The influence of the relative position of two flexible connector hinges on cross hinge model was given by analyzing the model with the Pseudo-rigid-body Model. It has been found out that the rigidity variety of the model requires a high assembly accuracy of whole gyro in coaxiality and orthogonality, which should supervise the whole assemblage and debugging technique.Keywords：Dynamic Tuned Gyro(DTG);cross-hinge model;Pseudo-rigid-body Model- 41
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Published：2020-08-12 -
Parameter optimization of novel cylinder type linear motor based on SVM and genetic algorithm
Abstract：The FEM (Finite Element Method) model of a novel linear motor was established, and then its correction was proofed. To obtain sample space used to establish the nonlinear regression model, the FEM simulation tests were arranged with the methods of orthogonal and random experimental design. Moreover, the nonlinear mathematical model of a novel linear motor was established using nonlinear regression method of the Support Vector Machine (SVM). Then the optimum structure parameters was obtained by optimizing the structure parameters with Genetic Algorithms(GA). At last,the FEM simulating results show that the parameter optimization method based on SVM and GA is feasible for researching the new cylinder type linear motor.Keywords：linear motor;Finite Element Method(FEM);Support Vector Machine(SVM);Genetic Algorithm(GA)- 40
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Published：2020-08-12 -
A remote-sensing image coding algorithm based on significant coefficients lifting
Abstract：MSE (Minimum Mean Square Error) is widely used as the criteria in image coding algorithm for providing much detail and important information of small target. In order to remain more detail information, an algorithm was proposed for determining the significant coefficients and the lifting value. The final coding bit-plane can be estimated by the entropy estimation of the DWT coefficients, and also the significant coefficients can be defined and the lifting value can be determined. The difference between proposed algorithm and ROI (Region-of-Interest) is that the definition of significant coefficients and the lifting value can be obtained from the coding image and the given coding rate so that the algorithm can be regard as the generality of ROI coding algorithm, but more flexible. The experimental results show that the small targets in remote-sensing images can be saved validly, while the detail information in reconstructed image are lost a little.Keywords：remote sensing image;image processing;image compression;significant coefficient;entropy estimation;bit-plane scaling- 39
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Published：2020-08-12 -
Nonlinear filtering algorithm for improving opto-electric target tracking
Abstract：In order to reduce the linear errors and improve the long-range target tracking accuracy, the Second-order debiased Converted Measurement Kalman Filter (SCMKF) algorithm is presented based on conventional CMKF, which is obtained by taking the second-order terms of a Taylor series expansion for the converted measurement functions to approximate the Cartesian coordinate errors. The mean and covariance of Cartesian measurement errors have been derived and the debiasing compensation is applied to SCMKF algorithm, which is helpful to improve long-range tracking accuracy. Simulation results show that the tracking accuracy of SCMKF is much higher than those of EKF and conventional CMKF, and the SCMKF provides faster convergence rate than the EKF.Keywords：target tracking;Second-order Debiased Converted Measurement Kalman Filter(SCMKF);Converted Measurement Kalman Filter(CMKF);nonlinear filtering- 38
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Published：2020-08-12 -
Immune recognition algorithm and its application to air target detection and recognition
Abstract：On the basis of the function of self/nonself recognition of natural immune system, a new immune recognition algorithm based on negative selection is presented. In proposed algorithm, the generation of detector set is improved and a new matching rule is also introduced to online matching detection. Moreover, the prior knowledge of the known target samples and the content update of the detector set are also considered. The proposed immune recognition algorithm is applied to detect and recognize the air targets, not only are the known types of targets detected and recognized, but also the unknown types of targets are detected. Experiment results show that the undetected error rate, the misrecognition error rate and the detection precision are 0.375%,0.006% and 99.563%,respectively. Meanwhile the detection process demonstrates good robustness for different targets.Keywords：artificial immune algorithm;self-nonself recognition;target recognition;negative selection- 39
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Published：2020-08-12 -
Improvement of spectral domain OCT image quality by linear interpolation and CCD response compensation
Abstract：Data collected by CCD camera is a function of wavelength in Spectral-Domain Optical Coherence Tomography (SDOCT) system. By consideration of a wavelength-depended response characteristics of CCD and the Fourier transform relationship between time (distance) and frequency (wave-number), the CCD data must be responsivity-compensated and resampled by linear interpolation in frequency space. Based on the above analysis, the CCD response compensation method and the linear interpolation arithmetic were suggested and tested by the sample imaging. Results show that signal-to-noise ratio (SNR) increases a 30% in proposed method and arithmetic mentioned above, and the OCT image quality is greatly improved.Keywords：Optical Coherence Tomography(OCT);CCD response;signal-to-noise ratio;linear interpolation;spectral-domain OCT- 79
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Published：2020-08-12
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