Chinese Version Light学术出版中心
Latest Issue
Issue 4 ， 2006
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Mathematical model and simulation for testing aspheric surface by annular subaperture stitching interferometry
Abstract：Annular subaperture stitching interferometry can test large-aperture, large relative aperture aspheric surfaces at high resolution, low cost and high efficiency without assistant parts. The basic principle of the stitching method was introduced, and the reasonable mathematical model and effective splicing algorithm were established based on least squares method and Zernike polynomial fitting. Meanwhile the computer simulation experiment was carried on, the PV and RMS of the full aperture phase distribution residual error are 0.0079 λand 0.0027λ,respectively. The results show that this splicing model and algorithm are accurate and feasible, and it can provide another quantitive measurement for testing aspheric surfaces besides null compensation, especially for large aperture asphere.Keywords：annular subaperture stitching;aspheric surface testing;Interferometry;Zernike polynomial fitting;Computer simulation- 60
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Published：2020-08-12 -
Calibration method for projection distortion in interferometric testing high order and off-axis aspheric surface with big aperture
Abstract：A calibration method was put forward for the projection distortion in interferometric testing of asphere surface. The method uses the Fiducial function of the interferometer to determine the relationship between the testing coordinate of the interferometer CCD and the coordinate of asphere mirror and make it orthogonalized fitting to calibrate the projection distortion of an off-axis and high order aspheric surface in interferometric testing phase, the fitting precision is 1.964 53 μm. The reconstructed interferogram was used in the computer control polishing experiment, the final precision of surface shape is rms λ/20(λ=0.632 8 μm). The experimental results show that the fitting precision satisfies the requirement of computer control polishing.Keywords：aspheric surface testing;Interferometry;Fiducial function;projection distortion;interferogram reconstruction;calibration- 75
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Published：2020-08-12 -
Research on computer controlled polishing technology of φ124 mm aspheric reaction-burned silicon carbide mirror
Abstract：Based on φ124 mm aspheric reaction-burned silicon carbide (RB-SiC) mirror, an aspheric computer controlled manufacturing center was designed, and an advanced wheeled polishing technology was developed to solve the problem of manufacturing and testing mid or small sized aspherics. The polishing equipment, abrasives and wheeled polishing technology were introduced. Some testing results of surface figure were given,it is showed that the first surface figure of the RB-SiC is 0.761 λ(PV) and 0.059 λ(RMS) (λ=0.632 8 μm), the second surface figure of the RB-SiC is 0.834 λ(PV) and 0.089 λ(RMS) (λ=0.632 8 μm),respectively.Keywords：RB-SiC;aspheric surface polishing;digital controlling technology;surface figure- 70
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Published：2020-08-12 -
Study of ultra-precision vertical grinding for aspheric lens mould
Abstract：The mechanism of ultra-precision machining, the algorithm of principle, the structures of hardware and software, the realization of Computer Aided Manufacture(CAM) system and the analysis of processing were studied and presented to deal with vertical grinding and Single Point Diamond Turning (SPDT). The CAM system of small size ultra-precision aspheric lens for vertical grinding (SGTCAM 1.0) was developed. The principle is proved to be correct and the results are up to the nano manufacturing precision with the form error under 100 nm and the surface smoothness under 5 nm. The conflicts between huge market requirements of optical products and the high price of conditional ultra-precision numerical machine tools will be resolved by the low developing costs of the system.Keywords：ultra-precision machining;vertical grinding;Single Point Diamond Turning(SPDT);aspheric lens mould;Computer Aided Manufacture(CAM)- 79
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Published：2020-08-12 -
Study on detection sensitivity of APS star tracker
Abstract：The expressions of Active Pixel Sensor(APS) detected star signal and APS noise were given, and Signal-noise Ratio (SNR) of star sensor was obtained. Based on the theory of inspecting signal from noise and optimal SNR threshold detection principle, the detection sensitivity model was established, and the corresponding APS star sensor detection limit was obtained based on APS IBIS5 and general optical system parameter.Keywords：Active Pixel Sensor(APS);star tracker;Signal-noise Ratio(SNR);detection sensitivity- 58
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Published：2020-08-12 -
Astronomical calibration method and observation analysis for high-accuracy star sensor
Abstract：A new method utilizing zenith observing to calibrate star sensor was proposed. By regarding the earth as the evenly rotational turntable and the star spots as the targets in this method, the star spots were transited the FOV evenly. Then the mathematic model that the coordinates of star spots correspond to the star images was established to calculate the position transfer function.This method can achieve the higher calibration accuracy, and it is also very simple. Through observing the real sky, the 2037 star maps continuously are calibrated and calculated in integration time of every star map of 80 ms. The results show the calibration error of the observed stars are 7.267 2″ and 6.922 0″ in the direction of α and δ, respectively, and the system calibration error is 10.036 2″. The obtained star maps are identified using the calibration result. It is indicated that optical axis directional error is 4.846 2″, which shows the calibration result is more perfect.Keywords：star sensor;calibration;zenith observing;transfer function- 55
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Published：2020-08-12 -
Hybrid diffractive/refractive system design of head-mounted projective display using retro-reflective screen
Abstract：A head-mounted projective display consisting of a pair of double-Gauss lens, a beam splitter, and a retro-reflective screen was designed, in which the feature parameters are 30 mm effective focal length, 23 mm exit pupil, 12 mm exit pupil size and 50° FOV (field of view). The system uses a retro-reflective screen to increase effectively the FOV of binocular design and reduce the distortion. It also aolopts a diffractive optical element (DOE)to reduce the size and weight of the system and improve the imaging quality. The total weight and the maximal diameter of projective lens are 10.8 g and 23.6 mm, the astigmatic and lateral color are 0.12 mm and 7.89 μm, and the distortion is less than 0.5 %. The minimum angular resolution of this system is 0.46 mrad, which is less than that of human eyes.Keywords：optical design;see-through head-mounted projective display;hybrid diffractive / refractive system;retro-reflective screen- 82
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Published：2020-08-12 -
Design and manufacture of a day and night optical low pass filter
Abstract：An optical low pass filter (OLPF) used in front of the sensor of a CCD camera was designed, according to the birefringent effect of quartz crystal and infrared cut-off optical filter. When a object is imaged on the discrete photoelectric detector at different spatial frequencies, OLPF can reduce the frequency-mixing phenomenon effectively and eliminate the effect of infrared light on color rendition to improve image quality of the CCD camera. Especially, when the objects such as fringes or grates are imaged on the sensor of the CCD camera, it can enhance the image distinction and eliminate the effects of the disturbing fringes of false color. Based on analyzing the operational principle of OLPF and function of IR-CUT optical filter, a special IR-CUT coating is designed to make the CCD camera obtain colored image in daytime and black-white image at night. The coating is deposited on thin quartz crystal sheet with double ion beam sputter technique, the measuring results show that the spectral character and image quality are perfect.Keywords：Optical Low Pass Filter(OLPF);infrared cut coating;double-ion beam sputtering- 110
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Published：2020-08-12 -
Analysis of hypersonic reentry radiation model
Abstract：Based on analyzing and computing the reentry object radiation model, the relationship between heat radiation, shock radiation, ablation radiation and retail radiation was given. By analysis of the facts of separating errors between measurement and numerical computation, a revised heat radiation model was established. With comparison of the theoretical results in revised model with the measuring results in exprimental field and simulation results in laboratory,it is concluded that the revised heart radiation model can give the real radiation properties of reentry for Apollo airplane by revision of heat radiation,shock radiation and retail radiation. Although there is difference in the shape and radiation of blunt and tine reentry objects, the gap can be amended by computing.Keywords：hypersonic radiation;radiation measurement;radiation intensity;wake;shock- 90
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Published：2020-08-12 -
High output and single-frequency ring Nd∶YVO4 laser end-pumped by diode laser
Abstract：A frequency-stability and intracavity frequency-doubled ring Nd∶YVO4/KTP laser end-pumped by a laser diode was designed and experimentally demonstrated. The laser was single-frequency operated by using a TGG, a Brewster polarizer, and a half-wave plate acted as optical diode in the cavity. Under the incident power of 9 W, the maximum green laser output is 1.1W, and conversion efficiency from light to light is 12.2%. Also,a passively Q-switched single-frequency laser in laser pulse duration of 100 ns and repetition rate of 21 kHz was achieved in a ring cavity by inserting a piece of Cr4+∶YAG as an intracavity laser pulse saturable absorber.Keywords：Nd∶YVO4 laser;green light laser;single-frequency laser;ring cavity;passively Q-switched- 69
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Published：2020-08-12 -
Passive Q-switching and mode-locking in a flashlamp-pumped Nd∶YAG laser with semiconductor saturable absorption mirror
Abstract：The passive Q-switched and mode-locked operations were realized in a flashlamp pumped Nd:YAG laser with the same Semiconductor Saturable Absorption Mirror(SESAM) under the different conditions. The experimental results show that for the shorter cavity length (L<90 cm), the laser only operates in the Q-switched mode and the pulse duration of the Q-switched pulse is 90 ns, and the amplitude modulation occurrs in the Q-switch pulse and the modulation gradually deepens with the increase of cavity length. When the cavity length is 140 cm and the radius of curvature of the full-reflective concave mirror is 300 cm, the Nd∶YAG laser is operated in the stable mode-locking and a pulse train with 27 mJ energy and 35 ps pulse duration is obtained. The differences of the passive mode-locking by the SESAM in the plane-concave stable resonator and the plane-convex unstable resonator lasers were experimentally compared and reasonably explained. It is concluded that the SESAM can replace organic dyes to become the best saturable absorber for the mode-locked operation of the flashlamp pumped Nd:YAG laser with larger output energy.Keywords：laser technology;Semiconductor Saturable Absorption Mirror (SESAM);Nd∶YAG laser;passive Q-modulation;passive mode-locking- 52
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Published：2020-08-12 -
Mechanism of varicosity treated by semiconductor laser intravenous irradiation
Abstract：The mechanism and the feasibility of the treatment of varicose veins by semiconductor laser intravenous irradiation were analyzed. By laser irradiation for the cephalic veins of the dogs, the interaction between vascular tissue, blood and the laser beam was analyzed. Research results indicate that varicosity can be treated by means of endovenous thrombus formation, blood vessel wall damnification and vessel enclosure induced by light absorption of haemoglobin irradiated by semiconductor laser. The mechanism of endovenous thrombus formation induced by laser irradiation is different from thromboplastic phlebitis, thus endovenous thrombus formation doesn’t affect whole body cruor function.Keywords：laser intravenous irradiation;varicosity;simiconductor laser- 55
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Published：2020-08-12 -
Study on precision PZT rotary step actuator with inner anchor/loosen
Abstract：A new precision rotary PZT actuator was proposed to improve its drive capabilities. Based on the piezoelectric (PZT) technology and the bionical principle,the PZT actuator uses a stator inner anchor/loosen and a distortion structure of thin shelf flexible hinge to improve the stability of anchor/loosen and step rotary. With a characteristic analysis from the finite element method,the results show that the new rotary PZT actuator works with high frequency (40 Hz), high speed (325 μrad/s), large travel (360°), high resolution(1 μrad/step) and high torque (30 N·cm) and it will be suitable for application to large travel and high resolution driving device, optical engineering, precision positioning and some micro-manipulation field.Keywords：rotary step actuator;piezoelectric element;stator inner anchoring/loosen;thin shelf flexible hinge;finite element analysis;resolution- 60
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- 4
Published：2020-08-12 -
Novel sophisticate stepping 2-DOF piezoelectric actuator
Abstract：By taking a piezoelectric stack as actuator element to realize 2-DOF precision driving in linear and rotary actuators arranged on flexible processing structure,a new piezoelectric stepping style precision 2-DOF actuator was designed. The stability and precision of the system was ensured by using unique double symmetry structure of anchoring/loosing. The finite element analysis of 2-DOF actuator combining with lots of experiments research proved the basic functions of the 2-DOF actuator. The test results show rotary driving of 2-DOF actuator reaches 0.45 μrad in resolution, 18 mm in travel, 0.04 rad·s-1 in velocity and 0.2 N·m in torque; linear driving reaches 40 nm in resolution, 20 mm in travel, 19.2 mm·min-1 in velocity and 10 N in driving power approximately.Keywords：2-DOF actuator;PZT stack;flexible hinge;sophisticate driving;finite element analysis- 46
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Published：2020-08-12 -
Investigation on design method of single chamber piezoelectric pump with cantilever valve
Abstract：Based on hydro-solid coupling theory, the cantilever valve piezoelectic pump was comprehensively analyzed, and its dynamic model was established. After analysis of the interactions between hydro-mass, output pressure, system damp and working frequency, it is concluded that the decrease of chamber height will enhance the working frequency and stabilization. Then the vibrator structure parameters were confirmed through computing the influence law between vibrator structure parameter and amount of deformation. The conclusions show that the best thickness ratio is from 0.45 to 0.55 and the best diameter ratio is 0.8 to 0.9 between piezoelectric ceramic layer and the metal plate layer, respectively. The influence of the output form on the output ability also be considered, the result shows that axial output is in favor of the enhamement the output ability of the pump.Keywords：piezoelectric pump;cantilever valve;piezoelectric ceramic;piezoelectric vibrator- 50
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Published：2020-08-12 -
Experimental research on a piezoelectric micro-pump for precision pumping
Abstract：A piezoelectric micro-pump with difference from the conventional pump in working principle and configuration was presented for pumping minutely in medicine. The pump prototype was designed and manufactured in laboratory,and a special power supply was made in order to obtain the method and rule for controlling precision pumping. By the systemic experimental research, it is concluded that the micro-pump has a stable work performance and precision pumping property, and is suitable for the microminiaturization. It can provide a useful reference for the development of micro-pump in practice and precision.Keywords：piezoelectric micro-pump;precision pumping- 69
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Published：2020-08-12 -
Study on insect-based flapping-wing system driven by piezoelectric bimorph
Abstract：On basis of the insect thorax-wing structure, a flapping-wing system consisting of the bimorph piezoelectric actuator, compliant mechanism, and bionic wing was presented. The principle of bimorph piezoelectric actuator was introduced, and the kinematics of compliant four-link mechanism was discussed. Using the quasi-state force theory, the output force at the insect-based wing for overcoming the aerodynamic damping was studied. The simulation results are helpful to determine the motion of insect-based wings. At the same time, the design of bimorph actuators and compliant mechanisms with optimal structure can improve the moving properties of flapping mechanism.Keywords：piezoelectric bimorph;compliant mechanism;flapping-wing mechanism;flapping micro air vehicle- 89
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Published：2020-08-12 -
Research on novel inertial piezoelectric actuator
Abstract：Based on controlling the orderly changes of the PZT moving mechanism and friction between supporting faces in mechanical way, a kind of inertial piezoelectric actuator was proposed. The relationship between the driving voltage and the driving force and the distance were analyzed, the structure of a new inertial piezoelectric actuator that can realize single dimension reciprocating motion was designed and manufactured. The experimental results show that the simple associated symmetry electrical signal can provide stable stepping movement with the speed of 1 mm/s, high resolution of 20 nm and maximum loading capacity of 1 000 g, it is expected that the proposed actuator will be widely applied to precision industry.Keywords：PZT;piezoelectricity actuator;microactuator;inertial drive;friction- 60
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Published：2020-08-12 -
Influence of piezoelectric vibrator and fluid on close noise field of pump
Abstract：The flexural vibration deformation and vibration radiation noise of piezoelectric vibrator were researched. The vibration equations were built to deduce the flexural vibration deformation functions. Then, the simplified vibration model of piezoelectric vibrator was introduced using vibration theories of micro-plane piston. Also, theoretical equation of sound pressure in close noise field and noise contribution equation of fluid in pump were deduced. Finally, with comparison of the theoretical calculation and experimental testing,the results show that the theoretical noise level of pump is 45 dB and the actual noise level is 37 dB, when the input frequency is 50 Hz. Under this frequency, the fluid in the pump exerts great influence on the pump noise, and the relative error between the testing value and theoretical calculation is 21.6%. The theoretical noise level is 61 dB and the actual noise level is 62 dB, when the input frequency is 120 Hz. In this case, fluid exerts little influence on the pump noise, and the relative error between the testing value and theoretical calculation is 1.6%. It is concluded that contribution quantities of piezoelectric vibrator and fluid in pump under different frequencies are obtained,which proves that the theory introduced by this research agrees with the experimental results well.Keywords：piezoelectric pump;piezoelectric vibrator;fluid;Noise;micro-plane piston- 53
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Published：2020-08-12 -
Research on precise traveling positioning stage driven by piezoelectric bimorph
Abstract：Driven by piezoelectric bimorph actuator, a new precise positioning stage run in two directions within a horizontal plane was presented. Based on the analysis of the working principle of stick-slip mechanism, a mathematical model describing its dynamic behavior was set up and simulated, experiments of traveling performance and bearing ability on the prototype were conducted. The results show that the designed stage has the advantages in simple structure, small volume, light weight, stable step size and large working range. As the driving voltage is below 30 V, the step error is less than 0.5μm. The bearing ability of the stage is approximately 7~8 times its own mass.Keywords：piezoelectric bimorph;precise positioning stage;stick-slip effect;micro-manipulation;Micro robot- 53
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Published：2020-08-12 -
Valve-less piezoelectric pump with unsymmetrical slope chamber bottom
Abstract：A novel valve-less piezoelectric pump with Unsymmetrical Slopes Chamber Bottom (USCB) was presented. It ingeniously takes advantage of the space of the pump chamber by developing its bottom into an unsymmetrical slopes shape along the direction of the axis of the inlet and outlet,as a result, a series of diffuse channels and nozzle channels are alternatively formed between the USCB and the piezoelectric vibrator which is opposite to the USCB. It can force the fluid in the pump chamber to produce net flow when the pump works, and the regular diffuse/nozzle elements fitted outside the chamber can be eliminated. Mathematic model of this pump is established to present the relationship between the mean energy loss and the volume flow rate of the pump. Based on the mathematic model, the working theory of the pump is analyzed. Finally, a real USCB valve-less piezoelectric pump is manufactured, and the theory above-mentioned was verified by the pump in a test. Under conditions of the working voltage of 220 V,working frequency of 50 Hz and the diameter of the piezoelectric vibrator in 30 mm, the pressure difference produced between the inlet and outlet is 4.67 mm column when the pump works on water.Keywords：valve-less piezoelectric pump;flow resistance;Unsymmetrical Slope Chamber Bottom(USCB)- 83
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Published：2020-08-12 -
Performance research on piezoelectric pumps based on holistic opening valve and cantilever valve
Abstract：The flow performance characteristics of two check valves, the holistic opening valve and the cantilever valve, were investigated. The prototype of piezoelectric pump with double series-wound chambers was manufactured in two form valves. The experimental results show that the self-suck ability and output flux of the piezoelectric pump with holistic opening valve are better than the piezoelectric pump with cantilever valve. With the alternating current of 200 V, the maximum self-suck height of the formers is 430 mm water column (the pressure is about 43 kPa), and the maximum output flux is 972 ml/min, the counterpart value of the latter piezoelectric pump is 410 water column and 480 ml/min, respectively.Keywords：piezoelectric pump;double series-wound chambers;passive check valve- 44
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Published：2020-08-12 -
Study on outer driving precision PZT linear step actuator
Abstract：A new precision linear PZT actuator was proposed to improve its drive capabilities. Based on the piezoelectric (PZT) technology,this paper adopts the principle of bionics and works with a new method of stator initiative anchoring/loosen and a distortion structure of double-side thin flexible hinge to solved the problems of anchoring/loosen, frequency, travelling, resolution and velocity. The experimental results show that the new linear PZT actuator has high frequency (100 Hz), high speed (30 mm/min), large travelling (>10 mm), high resolution(0.05 μm) and high load (100 N), it can be applied for large travelling and high resolution driving device, optics engineering, precision positioning and some micro-manipulation field.Keywords：piezoelectricactuator;step actuator;outer driving;double-side thin flexible hinge;resolution- 49
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Published：2020-08-12 -
Kinematic transmission property of a novel 3-P-2SS spherical platform manipulator
Abstract：The kinematic transmission property and distributions in work space of a novel 3-DOF 3-P-2SS spherical platform manipulator whose optimum kinematic transmission property is at the origin position were given. The orthogonal layout feature of the parallel manipulator is described and its kinematic transmission equations are developed based on its inverse displacement equations. The kinematic transmission indices of a 3-DOF 3-P-2SS spherical platform in direction of x、y and z are defined, respectively, so that the distributions of the indices in work space are given, which is significant for task planning of the manipulator.Keywords：3-DOF spherical platform manipulator;kinematic transmission property;work space- 72
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Published：2020-08-12 -
Optimization design of magnetic suspended gyroscope rotor
Abstract：The structure of a Control Momentum Gyroscope(CMG) was introducecl,in which gyroscope rotor with the rating rotation speed of 20,000 r/min and rating angular momentum of 200 N·ms is supported by permanent bias active magnetic bearing. The software of multidisciplinary design optimization (iSIGHT) and the software of Finite Element Analysis Software (ANSYS) were applied to optimize the rotor to reduce the mass of rotor. The results of optimization indicate that the mass of the rotor is decreased from 15.032 kg to 13.973 kg (is reduced by 7.1%), the safety factor is increased from 2.39 to 2.63 (is increased by 10%), the first resonance frequency is 1 313 Hz compare to original design results.Keywords：Control Moment Gyroscope(CMG);gyroscope rotor;permanent bias magnetic bearing;optimization design;Finite Element Method(FEM)- 56
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Published：2020-08-12 -
Measuring and analyzing elastic modulus of single voxels by femo-second two-photon photopolymerization
Abstract：An elastic modulus of single voxel was measured and analyzed to measure physical properties of materials. A tipless cantilever was used to measure the elastic modulus of the single voxel with the ellipsoid shape. Then allowing for the effect of deformation of the rest part on the result analysis, the contact model of elastic sphere on a flat surface was developed. In the base of calibrating the elastic constant of cantilever and analysis adhesion force, the force information from force curve was obtained and the elastic modulus of single voxel was calculated. At last,It is concladed that the elastic modulus of volex is generally lower than that of SCR500.Keywords：atomic force microscopy;single voxel;elastic modulus;tipless cantilever;mechanic model- 64
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Published：2020-08-12 -
Research of basic principles of E-O stabilization and tracking devices
Abstract：With whole stabilization ability, whole airspace tracking and no blind-zone,a high accuracy three-axis E-O stablilization and Tacking Devices(EOSTD) which uses a MEMS vlocity gyroscope as inertial feedback component was introduced. The coordinates in this device were analysized and the kinematic equation and the stabilization model were deduced based on the multi-body kinetic theory. The mathematical model indicates that different gyroscope installation methods can be used to realize three-axis attitude stabilization. Also the motion and distortion of image caused by the jitter of the Line-of Sight(LOS) were researched and the relationship between the LOS stabilization precision and the image stabilization precision was analyzed. The results show that two-axis EOSTD would cause large image stabilization error and three-axis EOSTD could restrain the image rotation around the LOS axis to reach a high stabilization precision.Keywords：E-O Stabilization and Tracking Device(EOSTD);Line-of-Sight(LOS);gyro stabilization;image stabilization;Precision- 85
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Published：2020-08-12 -
Servo system design for E-O stabilization and tracking devices
Abstract：The typical structure of the servo system of a E-O Stabilization and Tracking Devices(EOSTD) was introduced. Based on dSPACE hardware-in-the-loop simulation system, the common design process of velocity stabilization was researched. Aiming at the phase lag phenomena caused by digital frequency characteristic test, the phase compensation formula was proposed and some nonlinear compensation methods were discussed to achieve high stabilization precision. Analyzing deeply on the frequency coupling of the position tracking loop and the velocity stabilization loop, the corresponding de-coupling method and the ideal model of the position loop and the velocity loop above were presented. Based on that model, the conception of the isolation degree was discussed. Five typical instances were simulated, the position tracking and line of sight stabilization results were provided in the end. The results show the validity of the concerned conception.Keywords：E-O Stabilization and Tracking Device(EOSTD);servo system;position tracking;gyro stabilization;isolation degree- 57
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Published：2020-08-12 -
Research on application of MEMS gyro to servo system for E-O stabilization and tracking devices
Abstract：Aiming at the MEMS gyros used widely in the high accuracy electro-optical (E-O) stabilization and tracking devices, the impact of gyro noise on the E-O platform precision was studied. The analyzing result indicates that the gyro noise would cause the jitter of the Line of Sight (LOS) and slow drift on angle. Therefore, it is necessary to propose an effective filter method for restraining the gyro noise to obtain higher LOS stabilization precision. In this paper, the noise features were analyzed and the AR model of MEMS gyros was developed. By the Kalman filter method to denoise the signal of gyros primarily, the simulation results show that this method couldn’t achieve good performance. Following that, the threshold filter method according to the wavelet was researched, and the simulation data reveal its perfect performance on the denoising. Finally, the comparisons on relative merits between these two denoise methods were given.Keywords：E-O stabilization and tracking devices;MEMS gyro;Noise;Power Spectral Density(PSD);AR model;Kalman filter;wavelet transform;threshold- 49
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Published：2020-08-12 -
Restoration of motion-blurred aerial image
Abstract：The mechanism of a motion-blurred image generated from aerial imaging system was introduced. The mathematical model of motion-blurred image was established to give the point spread function of 2-dimensional motion blur,and the Wiener flter was utilized to remove image blur for aerial image. By the window technique,the edge error was restrained or reduced. The simulation results show that the Wiener filtering is effective in precision,which can get the restoration precision of 1 pixel.Keywords：aerial imaging;image blur;motion-blurred;Wiener filtering;Point Spread Function(PSF)- 53
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Published：2020-08-12 -
Effect of fabrication error on FSS transmission performance attenuation of double screen cross loop slot
Abstract：With the Galerkin moment method used in electric field integral equation, the frequency response attenuation performance produced by the fabrication error of two-layer Frequency Selective Surface(FSS) in the double screen frequency selective filter was analyzed. Based on the practical experience, the fabrication error analysis and construction models were built up. Moreover the practical numerical algorithm was proposed. According to the results of the numerical analysis, it is found that the amplitude attenuation of the double FSS frequency response is up to maximum value when the fabrication error is equal to a tenth unit cell periodic size. Further there is the phase delay and distortion when the fabrication excursion is parallel to the incident wave polarized direction. And there is much more phase delay, when the fabrication excursion is perpendicular to the incident wave polarized direction.Keywords：double screens cross loop slot;Frequency Selective Surface (FSS);unit cell fabrication error;phase distortion- 44
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Published：2020-08-12 -
Noise analysis and processing of ultraviolet ICCD for corona detection
Abstract：The noise sources and its characteristics of a ultraviolet camera based on generation Ⅱ ICCD were analyzed. Ultraviolet ICCD made by PROXITRONIC company was tested to give shot noise statistic data of the photocathode, which indicates the relationship between various MCP gain and shot noise created by photocathode. Based on statistic data, a restraining photocathode noise method was introduced to restrain the photocathode shot noise and decrease the affection on image processing. Application of this method to corona detection,results show that this method is a availability in restraining image noise and keeping the dynamic range of the camera.Keywords：ultraviolet deteetion;intensified charge coupled device;corona detection;shot noise;image processing- 75
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Published：2020-08-12 -
Application of multiwavelet based image processing to corona detection
Abstract：With combination of the multiwavelet threshold shrinkage, subband enhancement and image fusion, a image processing method accomplished by means of discrete multiwavelet transform was presented. In this method, Multi Wavelet Transform(MWT) is the first step and the MWT coefficients are denoised by soft threshold multiwavelet shrinkage. Then subband enhancement is used to enhance the edge related coefficients. A new adaptive weight average image fusion rule was proposed to merge the coefficients and acquire fused coefficients. The experimental results show that the proposed image processing method can produce visually acceptable image and reduce noise while the source image is enhanced. This method also can fuse details of input images and improve the locating precision of the corona detection system.Keywords：Multi Wavelet Transform(MWT);corona detection;image fusion;multiwavelet shrinkage;subband enhancement- 56
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Published：2020-08-12 -
Steganography of controlling histogram abnormality using feedback
Abstract：The histogram of an image is a key feature statistic, which is often searched by attackers for artifact caused by steganography. Therefore, keeping the abnormality of histogram minimum can be an efficient way to resist steganalysis based on histogram. For purpose of optimizing the stegnographic method, this paper analyzes the abnormality of histogram caused by +-1 embedding, and present a new idea of regulating the process of embedding by the feedback of the abnormality of histogram. Based on this new idea, the +-1 embedding method was improved.Experimental results show that using the method advanced here,the practical abnormality of histogram is theoretically minimum,and the security of steganography is consequently improved. It is also showed that this method is full of promise in Application to frequency domain.Keywords：steganography;least histogram abnormality;least variance embedding;least relative embedding- 42
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Published：2020-08-12 -
A lossy compression algorithm of remote sensing image suited to space-borne application
Abstract：A high quality lossy compression algorithm of remote sensing image was presented. After decomposition of the remote sensing image by D5/3 integer wavelet transform and analysis of the statistical characteristic and the energy distribution of wavelet coefficients in each sub-band, the human vision properties are introduced to control the quantification scheme of the algorithm. The important degree for target recognition is determined according to energy in each sub-band, and the different quantification threshold values and the quantification steps are chosen in the quantification. Finally, quantified data are coded in fixed bit-plane. The simulation experiment shows that this algorithm acquires the restoration images of PSNR(Peak Signal Noise Radio)>30 dB for all images of different contents and texture with certain CR, which keeps much high frequency information of the remote sensing image to realize the high quality image compression. Because of its simplicity, fastness, and small storage, the algorithm is easy to be realized in hardware and suitable for space-borne application.Keywords：remote sensing image;lossy compression;human vision;integer wavelet transform- 65
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Published：2020-08-12
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