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Issue 3 ， 2006
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Experimental investigation on co-doped double-clad high-power fiber laser in L-band
Abstract：A end-pumped co-doped double-clad high-power fiber laser in L-band was studied using a 976 nm pigtailed multimode tunable high brightness diode laser, clad-pumped erbium-ytterbium co-doped double-clad large-mode-area (LMA) fiber and the aspheric lenses coupler. The pumping coupling efficiency is more than 62% and the high efficiency continuous wave laser is gained in the Fabry Perot cavity. The experimental results show that a Er/Yb co-doped double clad native large-mode-area fiber laser can get output power of 4.3 W and the slope efficiency of 42% at signal central wavelenth of 1603 nm, when the double-clad fiber length is 30 m, the pumping power of entering fiber is 13.41 W.Keywords：Erbium-ytterbium co-doped optical fiber;double-clad fiber;cladding pump;fiber laser;Fabry Perot cavity- 73
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Published：2020-08-12 -
Study on curved compound eye imaging system
Abstract：Two kinds of curved compound eye image systems were studied. It is the first time that a curved field lens array was introduced into the curved compound eye image system to improve the image quality of the marginal Field of View(FOV) and enlarge the FOV. The model of a image system was designed and the ray trace was completed based the software LIGHTTOOLS. The FOVs of the two systems are 60° and 88°; the volume are 0.9 mm×0.9 mm×0.5 mm and 0.9 mm×0.9 mm×0.75 mm,respectively. The lithography technique to fabricate the curved microlens array on the curved substrate by using laser direct writing system was also given.Keywords：compound eye imaging system;Field of View(FOV);curved microlens array;Lithography- 80
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Published：2020-08-12 -
Design and measurement of a portable ionization chamber
Abstract：A portable ionization chamber mainly used to calibrate the wavelengths and investigate the resolutions power of beam lines was designed and developed in this paper.the vacuum and optical properties of 1 μm thick C3H6 and 0.1 μm thick Si3N4 windows were researched, the experiment data show that transmission rate of C3H6 is about 80% at 5 nm and Si3N4 filter is 15% at 7 nm, both of them can support 100 Pa pressure. The curves measured in physical surface beamline and MCD beamline were also given. It concludes that the performance of this portable ionization chamber meets the design demand of user.Keywords：ionization chamber;Beamline;resolution power;wavelength calibration- 60
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Published：2020-08-12 -
Focal depth in high-density optical storage system with a solid immersion lens
Abstract：The optical field distributions for two types of aplanatic Solid Immerision Lenses(SILs) of hemisphere (h-SIL) and supersphere (s-SIL) were analyzed by using the vector diffraction theory. The focal depths and spot sizes of the SILs for four materials (glass, silicon, gallium-phosphide, and diamond) were simulated. The results show that the focal depth of the h-SIL is greater than that of the s-SIL. The focal depth of the system is sensitive to the refractive index of the SIL and the spot size is sensitive to the illuminating wavelength. As NA (numerical aperture of lens) increases, the focal depth of the h-SIL decreases rapidly and monotonously, whereas the focal depth of the s-SIL has a one-period-only oscillatory behavior. Compared with the h-SIL, the s-SIL has an advantage that it lowers the demands for large-NA lenses in some applications, so that it is preferable to the applications in high-density optical storage and subtle photolithography.Keywords：solid immersion lens;high-density optical storage;focal depth- 41
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Published：2020-08-12 -
Influence of substrate on shielding effectiveness of metallic mesh under oblique incidence condition
Abstract：A double film method was employed to accurately estimate the influence of substrate on shielding effectiveness. By using the equivalent film model of free-standing mesh and preparing a thin mesh film on its substrate, this paper considers its influence on substrate interference to overcome the uncertainty of Konin’s method that merely considers the interference of the substrate itself, and to avoid the inaccuracy of Kohin’s transmission formulas of free-standing mesh at high frequency and large incident angle. To identify its validity, the metallic mesh with line width of 4.5 μm and period of 320 μm was fabricated on quartz glass by UV-lithography. The measuring results show that the shielding effectiveness is greater than 16 dB under 30° S-polarized incidence at 12~18 GHz, it is slightly below the theoretical value and has the same change trend with that. The analysis using the new method shows that for S-polarization,the shielding effectiveness decreases with oblique incidence; for P-polarization, it decreases also when incident angle is less than Brewster angle θB, but it increases abnormally when inciclent angle is larger than θB,and the largest alteration value varies with incident angle. Optimal shielding effectiveness can be obtained by optimizing substrate thickness without affect on the transparent property.Keywords：electromagnetic shielding;transparent conducting film;substrate;oblique incidence;metallic mesh- 49
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Published：2020-08-12 -
CO2 laser fabrication of biconical-tapered fiber and its laser power controlling
Abstract：Based on CO2 laser fabrication of fused-fiber taper rig developed by E. D. Timothy in 1999,a shorter focused lens was used to improve the laser power controlling in the paper. The Mie theory of cylindrical structures and the heat transfer modeling proposed by A.J.C. Grellier was used to derive the increment relation of the laser power with the drawbench distance. The relation was in section increase linearly by degrees for laser power controlling, which simplifies the computer control of the rig. The fused biconical-tapered fibers with 2~3 μm diameter in the waist were obtained in the experi ment, it indicates the size and shape of biconical-tapered fiber is consistent with the predicted one well.Keywords：laser processing;fiber taper;Mie scattering;laser energy;heat balance- 45
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Published：2020-08-12 -
Theoretical design of nanosecond near infrared KTP optical parametric oscillator
Abstract：A general theoretical design of nanosecond near infrared KTP optical parametric oscillator was presented. Based on the calculation and discussion on the phase-matching, walk-off angle, acceptance angle and effective nonlinear coefficient for the KTP crystal, and on the numerical simulations of the angle-tuning curve and gain curve, the tuning spectrum and cutting angle of the KTP was finally established as 1.35 ~2.0 μm and 59.6°, respectively. At the same time, the impact of the crystal length, walk-off angle and the output coupler’s reflectivity on the threshold of a Optical Parametric Oscillator (OPO) was analyzed. Besides, several methods of reducing the OPO threshold were summed up.Keywords：Optical Parametric Oscillator(OPO);near infrared laser;KTP crystal;angle-tuning;phase-matching- 52
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Published：2020-08-12 -
Research on off-axis conic asphere null testing using computer-aided alignment method
Abstract：The misalignment-induced aberrations by corrector and the support of the asphere were analyzed in this paper. A computed-aided alignment method was presented combining the interferometric test with the computer optimization for optical alignment, and a mathematical model was established to determine the misalignment. The simulated and actual experimental results of the alignment show that after four times alignment the test results of the asphere can reach up to 0.028λ(RMS) (λ=632.8 nm).Keywords：asphere testing;null corrector;alignment error;computer-aided alignment- 60
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Published：2020-08-12 -
Research on coupling efficiencies of ball lenses
Abstract：The coupling efficiencies of the ball lenses used in coupling of the laser diode(LD) and single mode fiber(SMF) were calculated and researched by a energy integration method. Research results indicate that when the single ball lens is used in the LD-ball lens-SMF system,the axial alignment tolerance is ±30 μm,the lateral alignment tolerance is ±1.0 μm and the tilting on the X-Y plane pivoting at the fiber tip is ±1.2°. When the double ball lenses are used in the LD-ball lenses-SMF system,the coupling loss of the tilting tolerance is maximum,the coupling loss of the lateral alignment tolerance is smaller than that of the tilting tolerance and the coupling loss of the axial alignment tolerance is minimum.Keywords：ball lens;coupling efficiency;axial alignment tolerance;lateral alignment tolerance;tilting tolerance- 39
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Published：2020-08-12 -
Manufacturing for ruling concave metal grating with a long focal length
Abstract：The ruling technique for concave metal grating with long curvature radius (namely long focal length) was studied. In order to rule the concave grating with a long focal length, a cutter frame with elastic thimble mode was designed and manufactured. It is available not only to plane grating, but also to concave grating with a long focal length. The mathematic expression of the relationship between the curvature radius of circular arc cutting edge of ruling tools for grating and the curvature radius of concave grating, the caliber of grating and the size of transverse direction of bit tool was given. The span of curvature radius of circular arc cutting edge was analyzed theoretically and the concave metal grating with curvature radius of 30 m for 10.6 μm laser system was manufactured. The testing results show that the quality of groove is preferable, and the diffraction efficiency is more than 96.8 percent.Keywords：IR laser;Concave grating;ruling tool for grating;cutter frame structure- 67
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Published：2020-08-12 -
Study on calculation of minimum laser energy of sheet metal deformation by laser shock forming
Abstract：The mechanism of laser shock deformation and the reasons of producing the shock wave were introduced,and the estimated formula of shockwave pressure was put forward, which shows clearly the relation between the peak value of shockwave and the overlay, energy absorbed layer, sheet metal properties and laser parameters. Based on both the formula and the tensile yield strength of sheet metal, minimum laser energy needed by deformation was estimated, the results show that the lowest pulse energy needed by the target deformation of stainless steel is about 11 J under the conditions of sheet thickness of 0.5 mm, the bore diameter of cavity die of 20 mm, the beam diameter of 6 mm and the pulse width of 25 ns. The experimental results also show that minimum energy calculation accords with critical value of deformation, and the deformation increases with the increase of laser energy in a nonlinear way. By studying on the calculation of minimum laser energy and the deformation experiment, the paper provides exactly a theoretical foundation for controlling and predicting deformation of sheet metal.Keywords：laser shock forming;shock wave;sheet metal;deformation;laser energy- 56
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Published：2020-08-12 -
Principle and realization of laser display technique
Abstract：The principle and technique to realize laser color video display were introduced. A large screen laser color display system was proposed on the basis of the blue, green and red diode pumped solid state lasers at wavelengths of 473 nm, 532 nm and 671 nm,the output powers of 1.3 W, 0.32 W and 3.5 W, respectively. The technical approach was presented to eliminate the laser interference, improve the uniformity of optical field, transform the chromaticity and extende the virtual color. The experimental results show that the laser projection display can agree with design well in fully saturated colors, higher contrast ratio and high resolution.Keywords：laser display;large screen display;laser TV;color TV- 52
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Published：2020-08-12 -
Design and analysis on a 2-DOF nanopositioning stage
Abstract：A two-degree-of-freedom (2-DOF) flexure hinge guided-motion nanopositioning stage was developed to align optical system, and the simplified modeling of the nanopositioning stage was discussed. The x and y direction stiffness and two natural frequencies of the nanopositioning stage were deduced in terms of the theory of structural mechanics. Theoretical analysis and Finite Element Analysis(FEA) on static and dynamic behaviors of the nanopositioning stage were performed, the comparative results of the theory, FEA and experiments show the accuracy of theory model and the validity of FEA. FEA also indicates that the stiffness, natural frequency and driving force will increase with decreasing hinge length and increasing hinge width in despite of increasing the maximum stress of the stage. The experimental results also show that dimension modification is available to controlling and optimizing natural frequency, displacement, stresses, and force to achieve the desired response of the nanopositioning system. Finally, a simple procedure to optimize dimensions of the nanopositioning stage was given.Keywords：flexure hinge;nanopositioning stage;Finite Element Analysis(FEA)- 56
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Published：2020-08-12 -
Spacing device with 700° slewing area for large photoelectric instrumentation
Abstract：According to the operating requirements of a large two-axis tracking and measuring system, a new spacing device with compact and skillful structure was researched and designed to realize the shafting revolving in 700° slewing area. The theoretical analysis and experimental results indicates that the device resolves the puzzle that the rotary shafting could pass the turning zero first but was confined second very well .The device could also provide timely position information of the rotary shafting to main control system,which meets the performance requirements of large photoelectric instrumentations properly .Keywords：photoelectric instrument;photoelectric tracking;slewing area;spacing device;moment inertia- 50
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Published：2020-08-12 -
Design of micromanipulation instrument for bio-microdissection
Abstract：This micromanipulation system provides a technology to procure pure population of targeted cells quickly and accurately for pathology research. Essential micromanipulations were executed by microdissection tool based on ultrasonic vibration (vibration frequency and amplitude at 15~50 kHz and 0~1 μm) and microcollection tool was based on vacuum adsorption (controllable pressure at 0~0.5 MPa). A 5 μm liver embedded sections were dissected and collected successfully in the experiments, the contrast testing experiment indicates that the micromanipulation system is applicable to bio-mcirodissection in high stability and accuracy,in which the ultrasonic vibration is no harm to tissue and vacuum adsorption is in good availability to collection samples.Keywords：biological microscopy;microdissection;Micromanipulation;Ultrasonic vibration;vacuum absorption- 26
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Published：2020-08-12 -
Study on neural network PID control for micro-displacement stage of Scanning Tunneling Microscope
Abstract：A control scheme for micro-displacement stage of Scanning Tunneling Microscope(STM) based on the neural network was proposed,in which piezoelectric ceramics is used as the micro-displacement actuator of stage to compensate the rough displacement of the servo mechanism. The principle of the actuator was analyzed and the mathematical model was set up. With the stage controlled by the neural-network PID controller in close loop,the weights of BP network and the parameters of PID controller could be adjusted to reduce the displacement error of stage by the function of self-learning and adaptability in real time. Experiments of stage displacement using the special electronic ceramics power were conducted. The results show that the response time for a micro displacement of 11.41 μm is shortened from 1.5 s to 1 s, and the stable error is reduced from 3.13% to 1.05%. The stability and positioning precision are improved and the performance of Scanning Tunneling Microscope is enhanced compared with the traditional PID controller.Keywords：Scanning Tunneling Microscope(STM);precision stage;PID control;neural network;Adaptive control- 67
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Published：2020-08-12 -
Design and analysis of 1-DOF nano-positioning stage
Abstract：A novel 1-DOF displacement stage with large motion range and nano-positioning precision was developed. The stage is a set of two-grades mechanism by coarse and fine positioning,and a diffraction grating is fixed to the stage to form a close loop displacement measuring system. The displacement range of the stage is 0~6 mm and the positioning resolution is 1 nm. A electromechanicel coupling modal of PZT actuated and flexure hinge guided fine positioning mechanism was established, its model and mechanics analysis was performed. The finite element analysis soft ANSYS was also used to simulate the behavior of the stage and an application example was presented at the last of the paper.Keywords：nano-positioning stage;flexure hinge;PZT actuator;finite element analysis;model analysis- 47
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Published：2020-08-12 -
Study on single-plane biaxial balance monitor system in ultra-precision aspheric grinding
Abstract：An intelligent single-plane biaxial balance monitor system in ultra-precision grinding was put forward. For influence of the interaction of vibration of wheel and workpiece on a ripple on the workpiece surface, this system adopts single-plane balance correction for the principal axises of wheel and workpiece synchronouslly, and it analyzes integrally the balance condition of whole system and the surface error of workpiece by processing the vibration data of wheel and worpiece together. The experimental results show that this system can reduce the surface error of workpiece and decrease the abrasion of wheel to improve machining accuracy. The measuring data prove the correction of integral analyses.Keywords：aspheric machining;grinding;vibration;wheel;Workpiece;monitoring system- 65
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Published：2020-08-12 -
Design of micro piezoelectric ceramic rod angular rate gyro
Abstract：This paper developed a micro angular rate gyro based on micro piezoelectric ceramic rod structure instead of the sensitive double-deck structure as well as piezoelectric ceramic strain foils, and designed a phase-sensitive detection circuit. By taking the miniature ceramic rod which is easily to machine high accuracy as sensitive structure, and by printing and polarizing six belt-shaped electrodes above it to constitute three pairs of electrodes, this paper designed package and the phase-sensitive detection circuit in the system so that it effectively reduced the sensitive structure size and improved its processing precision to realize the angular rate gyro microminiaturization. Calibration results indicate that this angular rate gyro has good linearity with correlation coefficient of 0.9996, and high precision with standard error of 0.0036.Keywords：micro piezoelectric ceramic rod;angular rate gyro;phase-sensitive detection circuit;calibration- 49
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Published：2020-08-12 -
Analysis on eddy current effect in giant magnetostriction with finite element method
Abstract：To compensate the nonlinear displacement of the giant magnetostrictive micro-displacement actuator caused by temperature and eddy current induced reverse magnetic field, a mathematic model used to describe the distributing and magnitude of eddy current in the giant magnetostrictive micro-displacement actuator was derived based on electromagnetic theory. Galerkin method and Newton-Laphson iteration were used to analyze the mathematic model of eddy current. The electromagnetic field distributing of cross-section in the giant magnetostriction micro-displacement was calculated by this mathematic model to gain the corresponding relation of eddy current and frequency of input current in actuator. When the frequency of input current is greater than 1 kHz, the difference of the dissipation of eddy current induced magnetic field calculated by eddy current model of finite element with magnetic field intensity measured actually is 4.6 mT,which shows that the model can effectively compensate the dissipation of the giant magnetostriction micro-displacement actuator caused by eddy current.Keywords：giant magnetostriction;eddy current effect;Finite Element Analysis(FEA);Galerkin method- 51
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Published：2020-08-12 -
Research on SVM model of a novel cylinder linear motor
Abstract：Through establishing the Finite Element Model(FEM) of a novel linear motor and testing its prototype, a kind of method used in simulating the character of linear motors was obtained. By means of the method of the orthogonal experimental design and the random experimental design, the sample space of the character parameters of the linear motors was established,and by the nonlinear regression method of the Support Vector Machine (SVM), the nonlinear mathematic model of a novel linear motor was given. Comparing the FEM model with the SVM model in aspect of consistency and computing speed, the authenticity and effectiveness of the SVM model were confirmed.Keywords：linear motor;Finite Element Model(FEM);Support Vector Machine (SVM);nonlinear model- 45
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Published：2020-08-12 -
Research of a novel dual-driven 2-DOF planar parallel robot
Abstract：A novel high speed/high precision robot with two permanent linear motors drived a 2-DOF planar parallel piezo smart mechanism was proposed. By taking a linear motors as master driver to realize fast precision positioning in large displacement motion and by preshaping input command technique to suppress vibration, and using a piezo as slave driver and closed loop feedback controller to restrain residual vibration, the dual driving structure could supress the vibration of robot ideally. Experiment results indicate that this approach realizes high performance point-to-point control preciselly, the maximum acceleration is 2 g, steady time is less than 150 ms, and repeatability is less than ±5 μm.Keywords：flexible robot;vibration control;dual driving- 75
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Published：2020-08-12 -
Adjusting gap of relay springs by using laser beam
Abstract：The principle of laser-adjusting and the method of laser-measuring were described and applied to adjust the gaps of one model relay. A plenty of tests and measurements for adjusting relay’s springs by laser beam were finished. After data analyzed, several results were summarized and shown as follows: the laser-adjusting quantum h is in linear direct proportion to the distance x2 between measuring point and adjusting point, and the formula can be expressed by h=kx2. The laser power P and the irradiation time t are approximate parabola relation curves to adjusting quantum h. The stronger the power P and the longer the irradiation time t, the bigger the quantum h at the rise phase, But when it is over the inflexion, the results are opposite. The experimental results also show that there is no negative influence of laser-adjusting on the relay’s mechanical life. It is feasible for adjusting the relay’s gap by laser beam when the laser power P and the time t set equal each other. With combining the test data of the relay’s gap, it is known that the gap of the most relays on the assembly line can be adjusted correctly after adjusting the settled spring only, which will be more efficiency in comparon of laser-adjusting with manual-adjusting.Keywords：relay;spring;gap;laser-measuring;laser-adjusting- 49
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Published：2020-08-12 -
Micro-assembly auto-focusing system based on image processing
Abstract：Based on the image processing technology,an auto-focusing system consisted of optical microscope, CCD, moment motor and drive gear etc,was presented. In combination of coarse with fine adjustment method,this system applied Krisch-image edge gradient operator to evaluate the entire microscopic image of the micro-object for its coarse focus position, the system also used the sharpness function based on high frequency component to evaluate the certain domain of the microscopic image for fine adjustment. The sharpness functions used in the experiment were programmed with Visual C++, and the experimental results show that the position accuracy of auto-focusing system is less than ±4.8 μm, which satisfies the focusing requirement of the micro-assembly.Keywords：micro-assembly;auto-focusing;image smoothing;resolution evaluation function- 62
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Published：2020-08-12 -
Improving Chinese lip-reading recognizing rate by unsymmetrical lip contour model
Abstract：Based on analyzing the side-face image and full-face image, a new model was presented to extract the degree of pouting from a lip contour. At the same time, the differential coefficient of some parameters to describe dynamic characteristic of the lip contour were calculated. Experimental results based on a small database of Chinese words show that the parameters from unsymmetrical lip contour model improve the recognizing rate in more than 25%,which is superior to those of the traditional symmetrical lip contour model.Keywords：lip contour;symmetrical model;unsymmetrical model;difference parameters- 69
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Published：2020-08-12 -
A multi-layered decomposition of hyper-spectral image compression
Abstract：Based on the strong spectral correlation of a hyper-spectral image,a multi-layered decomposition compression method combined prediction algorithm with transform encoding algorithm was proposed. Taking the same loss image shared for several neighbor bands as the prediction image,the sensitivity of transmission error for prediction algorithm was improved.The loss image was created by using quad-tree partitioning of original image and compressing the input image with a wavelet basis. After calculating the residual image between the original and loss image data, the rid of the spectral correlation was obtained,and a local cosine transform was used for removing the spatial correlation of residual image. The experimental results indicate that the compression ratio(CR) of the image is higher than 7.2 when the Peak Signal Noise Radio(PSNR) range is about 50 dB,which shows that the algorithm is efficient.Keywords：information optics;image compression;hyper-spectral image;multi-layered decomposition- 40
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Published：2020-08-12 -
Dummy solid camera calibration technology using genetic algorithm
Abstract：A dummy solid camera calibration method based on genetic algorithm was presented. Using the infrared LE moved with the CMM probe according to some distance,the solid calibration template was formed to estimate the initialization calibration parameters by the Singular Value Decomposition(SVD) algorithm. Finally, the genetic algorithm was used to optimize and determine all calibration parameters. The experimental results show that the inverse result error of calibration point is less than 0.04 mm, and the calibration method can resolve the problem of high-precision camera calibration, and also can meet the requirement of high-precision camera calibration in the field of large scale vision coordinate measurement.Keywords：large scale vision measurement;camera calibration;distortions correction;genetic algorithm;solid calibration- 54
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Published：2020-08-12 -
Calculation of image motion velocity considering airplane gesture angle in oblique aerial camera
Abstract：It is necessary to improve the imaging quality and enhance the image resolution of the camera in photographing by Image Motion Compension(IMC),when the image motion is brought out in airplane’s continuing flight and altering airplane gesture angles including pitching angle,yawing angle and rolling angle. In this paper, a mathematical model was established in order to obtain the velocity of image motion while the gesture angles were changing, in which it is supposed that the rotation of the coordinate system is equal to the change of the gesture angles. The velocity of image motion was calculated out by analyzing the course of the gesture angle’s change and utilizing the matrix transform relation between the different coordinates of the same position after the coordinate system’s rotation in changing single angle. The method can be deduced to the situation of all the three angles’ changing. The result is proved that it is an efficient method to calculate the image motion’s velocity for the oblique frame aerial camera. This method is intuitionistic,practical and easy to be expanded to the camera fixed in satellite also.Keywords：aerial camera;gesture angle;image motion velocity;image motion compensation;coordinate system rotation- 65
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Published：2020-08-12 -
Study on synchronization of 1D-k3 additive Cellular Automata
Abstract：Cellular Automata (CA) is a dynamical system in which space and time are discrete.Due to the properties of additive CA in simple regular structure, local interaction, and high parallel information processing, it is easy to implement the system’s synchronization by hardware. Based the rule characteristics of additire CA, a new synchronization way of additive CA was presented and 1-D three-neighborhood Additive 90 CA synchronization example in the periodic and null boundary was given. The results show that 90 CA error rate in evolution is approximately 50 percent. For analysis on application of the additive CA to cipher code,it is showed that the investigation will be of great value in data encryption.Keywords：cellular automata;synchronization;90 rule- 52
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Published：2020-08-12 -
Image processing based on integral lifting scheme and its implementation by DSP
Abstract：Based on the parallel feature of Digital Signal Processor (DSP), the parallel architecture of 2-D integral lifting scheme was presented to perform simultaneously data transfer and wavelet transform with the strategy of ping-pong buffer. The column transform method based on line transform permits column transform in a few line transform results only; multiplication operations are substituted by shift operations to enhance the transform speed. The whole architecture is optimized in the pipelined design way to achieve higher hardware utilization and decrease the intermediate data quantity. The transform speed of optimized algorithm is 85 frame per second and 15 times faster than original algorithm's. The Peek Signal-to-noise Ratio(PSNR) of optimized algorithm is lower than original algorithm’s, but it is over 42 dB, thereby optimized algorithm has high application value.Keywords：DSP;lifting scheme;ping-pong buffer;wavelet transfer;image processing- 49
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Published：2020-08-12 -
X-ray automatic inspection techniques for carbon product defects
Abstract：Based on the characteristic of X-ray detection images of carbon product, the defect extraction and recognition techniques were present to remove background and enhance image successfully with target boundary extraction algorithm and image enhancement algorithm on wavelet transform. In order to eliminate the effect of noise, a mathematical morphology combining with iteration threshold segmentation method was adopted to extract defect from a image without background,it was proved to be very effective. An algorithm based on genetic strategy and BP neural network is proposed for the selection and recognition of defects, the results show that the veracity of defects recognition is 95%. These techniques are then combined into an automatic inspection system for carbon material.Keywords：carbon product;X-ray image;defect extraction;defect recognition- 42
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Published：2020-08-12 -
Study on edge detection and target recognition in complex background
Abstract：Based on the analysis of traditional edge detection operator of mathematical morphology, a multi-structuring elements edge detection operator of mathematical morphology was proposed, which could suppress noise as much as possible while preserving fine details. The threshold acquired by weighted average of gray levels was used to binarize the image to improve image edge. On the basis of characters of edge pixels, complexity and aspect ratio of minimum enclosing rectangle, a overall fuzzy evaluating technique was utilized to recoginize the target by calculating the characteristic evaluating function and membership degree function. The results of simulation experiments demonstrate that the proposed method could suppress noise effectively and extract target edge from complex background efficiently, and the target in complex background could be detected reliably by overall fuzzy evaluating technique.Keywords：mathematical morphology;multi-structuring element;complex background;edge detection;target recognition- 67
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Published：2020-08-12 -
Extend-beacon tracking for deep space optical communication based on phase-correlation
Abstract：A extend-beacon tracking method for deep space optical communication was proposed, and the operational principle of the method was given.By storing a beacon image in aircraft as reference and regarding actual beacon image as the sum of reference image and additive Gaussian white noise, the values of rotation and translation for beacon image were calculated according to phase correlation and DFT(Discrete Fourier Transfer). The theory analysis and computer simulation show that the tracking error can be constrained below 0.5 pixels. The computer simulation based on different SNR (signal noise rate) indicates that the change of a calculation error is little, it shows that the method has the advantage of rejecting noise and it is a feasible strategy for deep space optical communication.Keywords：deep space optical communication;extend-beacon;Discrete Fourier Transfer(DFT);phase-correlation- 50
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Published：2020-08-12 -
Estimation of PSF of image system using modified SVD method
Abstract：To improve the performance of image restoration algorithms, a modified Singular Value Decomposition(SVD) method was proposed to estimate the Point Spread Function (PSF) of an imaging system. Using the discrete image degradation model, a block-based SVD filter scheme was applied for the image denoising with an automatically determined singular value rank. After the spectra of PSF singular vectors were estimated under an exponential model for the averaged spectra of un-degraded image singular vectors, the IFFT was used to get the time-domain estimation of the PSF. The experimental results show that this proposed method can be applied to estimate the PSF of the imaging system under a wide SNR range and its performance is better than the original method. It may be used as an effective method for the image preprocessing in image restoration problems.Keywords：image restoration;Point Spread Function(PSF);block-based Singular Value Decomposition(SVD);image degradation;exponential model of averaged spectra- 48
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Published：2020-08-12
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