Chinese Version Light学术出版中心
Latest Issue
Issue 3 ， 2010
-
Stray light control lens for Xing Long 1-meter optical telescope
Abstract：To reduce the stray light effect of Xing Long 1-meter optical telescope, an objective lens was developed,and simulations and observations were undertaken to evaluate the lens. The Point Source Normalized Irradiance Transmission(PSNIT) for“dome-telescope”and “dome-telescope-lens” systems was calculated with the code Tracepro and observations were carried out at a moon night. The calculation results indicate that for the stray light sources located at off-axis angle within 30°, the PSNITs of the observational system, including dome,1 m telescope and the lens, have been lower than 10-10.Furthermore,the observation results for stars located at 22°and 25°off-axis angles away from the moon in May 26th 2008 indicate that the observational SNR of the system has been increased by a factor about 1.4 with the lens. These results show that for the 1-meter optical telescope the stray light is reduced and the photometric accuracy and limiting magnitude are improved by the lens effectively- 53
- |
- 7
- |
- 6
Published：2020-08-13 -
Fourier telescopy imaging via sparse sampling
Abstract：In order to realize rapid imaging of Fourier telescopy, an approach of image reconstruction via sparse sampling is proposed and the accurate image reconstruction by using sparse Fourier samples is investigated. Firstly, based on compressed sensing theory and the sparsity or compressiveness of object images in transformation domains, the optimization model of image reconstruction via sparse sampling is established. Then, appropriate masks for random and sparse sampling are constructed to sample Fourier components of object images. Finally, object images are reconstructed accurately through nonlinear optimization by using the random and sparse samples. Experimental results indicate that the RMS errors of reconstructed images between 20%~30% sampling and full sampling are only 4%~6%, which shows that the proposed approach can realize accurate image reconstruction by using random and sparse Fourier samples and can reduce the amount of measurement samples greatly.The method lowers the requirements of costs and complexity to Fourier telescopy systems for rapid imaging effectively.- 63
- |
- 9
- |
- 21
Published：2020-08-13 -
Optimization of wavefront coding imaging systems based on ZEMAX user defined operands
Abstract：As the design of phase mask in wavefront coding imaging systems is complex and the aberration of original optics cannot be taken into consideration, two new design methods are proposed based on the popular optical software ZEMAX. By using ZPL macros, the user defined operands are written to optimize the energy concentration and consistency of the point spread function, and the depth of focus of the optimized rotationally symmetric phase mask is 5.5 times as large as that of traditional imaging systems at the criterion of Strehl ratio larger than 0.8. By using an externally defined and compiled C program, the user defined operands are written to optimize the defocus invariance of modulation transfer function, and the depth of focus of the optimized odd symmetric phase mask is 12.5 times as large as that of traditional imaging systems. However,the depth of focus of the cubic phase mask is only 10.1 times as large as that of traditional one in the same condition.These results show that the design methods proposed are practical and effective.- 46
- |
- 7
- |
- 4
Published：2020-08-13 -
Experiments of extending depth of focus through wave-front coding technology
Abstract：In order to extend the depth of focus of optical systems, an optical-digital system using wave-front coding technology was established. By adding a phase mask at the aperture stop of a general optical system combined with post-digital processing, this system extended its depth of focus greatly. Firstly, the proposal, development and theoretical basis of wave-front coding were briefly introduced; then, a triplet system with a cubic-phase-plate was designed, and the imaging characteristics of the traditional system and wave-front coding system were analyzed using CODEV.Furthermore, the three-dimensional contour maps of Point Spread Function (PSF) and the Modulation Transfer Function(MTF) curves within defocus of ±40 times were obtained. Finally, the imaging experiment of manufactured system was carried out, and the images of a traditional system and a wave-front coding system before and after decoding were compared. The results show that the wave-front coding system can extend the depth of focus by 40 times compared with the traditional system while maintaining the light flux and image plane resolution.- 63
- |
- 7
- |
- 3
Published：2020-08-13 -
Development of 1-D position-sensitive ionization chamber used in SSRF
Abstract：A one-dimensional position-sensitive ionization chamber has been designed and fabricated. The cathode of this ionization chamber consists of two selfsame units that are insulated from each other and each unit is divided into two-way cleft plates. From current output signals, it can offer the intensity and position of X-ray beam. The ionization chamber was installed on a SSRF macromolecular crystallography beamline and its performance was tested. In the test,a standard ionization chamber was used for the comparison of beam intensity measurement. The one-dimensional position-sensitive ionization chamber was fixed on a high precision linear motor stage and was driven on horizontaldirection to scan the beam position step by step, In which the beam energy was set to be 8 keV and the scanning range to be 10 mm. The position scan was repeated 12 times. The tested specifications were plateau curves, linearity, position resolution and the intensity of beam. The results indicate that the 1-D position-sensitive ionization chamber has a good linearity and its position resolution is better than 20 μm and linear measuring range is 6 mm. Moreover,it will be installed on the beamline of SSRF for monitoring the stability of beam.- 48
- |
- 6
- |
- 1
Published：2020-08-13 -
Smile effect and package technique for diode laser arrays
Abstract：To reduce the smile effect caused by the thermal stress and to improve the beam quality of laser diode arrays, a set of optical system is designed for measuring the smile effect. By using an image amplification method, the smile effect of a laser diode array is accurately measured, and the measurement error is about ±0.1 μm. The quantitative characterization of the smile effect is a key technology to compare objectively the different measuring methods for smile effect and to reduce or eliminate the smile effect. According to analysis of the measurement results,the diode laser array package technique about reflow soldering is optimized, and the smile effect has been controlled within ±0.5 μm. As the smile effect values of the laser diode array is decreased and the beam quality of the laser diode array is improved significantly,the proposed method provides a technological fundation for development of small fiber diameters and high beam quality diode lasers.- 55
- |
- 7
- |
- 11
Published：2020-08-13 -
High flattening C+L-band erbium-doped superfluorescent light source with three-stage two-pumping structure
Abstract：In order to realize a high flattening C+L-band fiber source by C band matching L band closely, a superfluorescent light source structure with three-stage two-pumping is presented. Firstly, the experimental equipment is composed of three erbium-doped fibers, two 980 nm LDs,a Wavelength Division Multiplexer (WDM),an isolater（ISO）and a 3 dB coupler. Then, a high flattening C+L-band fiber source is achieved by optimizing the lengths of three erbium-doped fibers and adjusting the powers of two pumps, and the mechanism of production is also analyzed. Experimental results indicate that when the lengths of three fibers are 11.5 m, 53 m, 6.5 m and the powers of the two pumps are 65 mW, 115 mW respectively, the light source can offer a linewidth in 75.68 nm with a power ripple of 3 dB, and the flatness of the spectra from 1 543 nm to 1 603 nm is less than ±1.3 dB without any external spectral filters. The high flattening C+L-band superfluorescent light source can satisfy the requirements of the optical fiber sensing and optical fiber communication systems.- 57
- |
- 6
- |
- 5
Published：2020-08-13 -
Co-focus experiment of segmented-mirror active optics
Abstract：A co-focus experiment system of segmented-mirror active optics is built to realize the co-focus fine-tuning of a segmented-mirror. In this system, the segmented-mirror consists of three hexagonal submirrors with 300 mm side to side, and the shape of each submirror is spherical with 2 000 mm radius. A Shack-Hartmann sensor is used for co-focus measurement, and six micro-displacement translation stages in this system are used for adjusting the co-focus and tilt of the two sub mirrors. Each sub-mirror corresponds to 36 sub-apertures of the Shack-Hartmann sensor,and the co-focus errors can be calculated by the position deviation of the spots formed by the sub-apertures. After fine-tuning for micro-displacement translation stages, the rms de-focus error in the optical axis direction and the rms tilt errors in two orthogonal dimentions of the sub mirror can be controlled to less than 1 μm and 0.02″,respectivelly. The experiment shows that the method used in this system is also compatible to the co-focus calibration and real time adjustment of the large segmented mirror telescope.Keywords：segmented mirror；co-focus；Shack-Hartmann sensor- 65
- |
- 9
- |
- 7
Published：2020-08-13 -
Demonstration and analysis on correction of0.5 m ultra-thin mirror with active supports
Abstract：In order to study correcting capabilities for figure errors of ultra-thin mirrors with active supports, a 0.5 m demonstration mirror is designed and tested. Firstly, the relevant relations between actuator forces and figure forms are analyzed, and some lower-order figure errors, such as primary spherical aberration, coma, astigmatism and distortion due to gravity, are introduced. Then, the optimization objective is set up, and the Sequential Quadratic Programming (SQP) method for nonlinear constraint problem is applied to calculating optimum actuator forces. The residual figure errors of the ultra-thin mirror are given. Simulation analysis shows that by using the actuator arrangement proposed in this paper,the normalized primary spherical aberration, coma, astigmatism as well as their summation can be corrected to be less than λ/24 rms,and the correcting capability for astigmatism is the strongest and for spherical aberration and coma are less; moreover,the deformation due to gravity combined with the summation of above three lower-order aberrations can also be corrected to be less than λ/24 rms. After the actual surface errors from the interferometry based on the 0.5 m demonstration mirror are given, the optimum actuator forces and form errors are solved. The results show that the surface quality is about λ/7 rms ,which is in accord with the test data. The causes that the figure error can not meet the desired objective are analyzed,then an improved method is proposed. By the method, the figure error of the 0.5 m ultra-thin mirror with active supports satisfies the requirements equal to or less than λ/20 rms.- 61
- |
- 6
- |
- 7
Published：2020-08-13 -
Design on hyper-spectral imaging system with harmonic diffraction element in medium and long infrared
Abstract：Objective: In order to get enough information, make the best of the spectral information of medium and long infrared, this article establishes a harmonic diffractive / refractive optical system in middle and long infrared. Method: In this paper, the hyper-spectral imaging system in medium and long infrared has obtained more than 200 spectral images, during medium-wave infrared band 3.7-4.8µm and long-wave infrared band 8.5-12µm, based on the special large dispersion capability of harmonic diffractive element. Result: The design results show that the design: at 18 lines/mm, the optical modulation transfer function is greater than 0.53 in medium-wave infrared band; at 13 lines/mm the optical modulation transfer is greater than 0.51 in long-wave infrared band; the RMS spot diameter is less than 30 in medium-wave infrared band and less than 37 in long-wave infrared band. Conclusion: The optical modulation transfer function at all wavelengths are close to the diffraction limit; and point of the RMS spot diameter can match with the existing detector pixel size.Keywords：Infrared;harmonic diffraction lens;hyper-spectral;imaging optical system- 35
- |
- 9
- |
- 7
Published：2020-08-13 -
Near-Infrared Diffuse Reflectance Spectroscopy and Partial Least Square Method was Applied to Rapid Analysis of Soil Zinc Content
Abstract：The quantification model of zinc rapid analysis in the soil was established by using near-infrared diffuse reflectance spectroscopy and partial least square (PLS) method, and the wave band was optimal selected. All the samples were divided into calibration set and prediction set based on the prediction effect of single wavelength model. And the spectra were pretreated by multiplicative scatter correction (MSC) and Savitzky-Golay (SG) smoothing method. The following five wave bands were selected: the whole region 400-2500nm、400-1100nm、1100-1900nm、1900-2500nm、580-900nm. By adopting the original spectra, the first derivative spectra and the second derivative spectra respectively in each band, 15 calibration models were constructed. By simultaneous adjusting SG smoothing point’s number and PLS factor，comparing of many PLS computational experiments for each model, the best model was selected according to the prediction effect. The results show that the prediction effect of the model using the first derivative spectra on 1900-2500nm is the best, and the prediction correlation coefficient (RP), RMSEP and RRMSEP are 0.806, 31.0mg/kg, and 19.96% respectively. It shows that 1900-2500nm can replace the whole band get better calibration effect, and provide basis for the design of special soil near-infrared spectroscopy instrument.- 28
- |
- 7
- |
- 17
Published：2020-08-13 -
The Application of active-Athermalisation compensation in airborne IR optical system
Abstract：Analyzed the ambiance temperature affects the image quality of IR optical system, base on the precision requirement of two FOV lens for focus compensation mechanics, an active athermal compensation method was proposed. Which based on the stepper motor and linear hall component，experiment results demonstrate that the method proposed can get 0.02mm compensation precision, and the MTF attenuation of IR optical system was within 0.05.Keywords：IR optical system;athermalisation;active compensation- 38
- |
- 13
- |
- 18
Published：2020-08-13 -
Experimental Study on Effect of Beam Spreading of Far-field on Aiming Deviation
Abstract：In the far-field atmosphere and the aiming process of laser spot, as atmospheric turbulent results in beam spreading and wander, the pointing accuracy of laser is dropped seriously. Based on the modified Von Karman turbulence spectrum and the theory of partially coherent beam propagating though atmospheric turbulence, a light field simulation software of Gaussian beam propagating though atmospheric turbulence was developed, and the transmission characteristics of beam propagating through the far-field strong atmospheric turbulence are investigated when Gauss pulsed beams propagate in the far-field atmospheric turbulent in a certain meteorological conditions.A test system of the dynamic aiming deviation of laser optical axis, in allusion to the phenomenon of pointing bias, especially under different transmission distance was designed, and the relationship between beam spreading and the variation of gravity center of laser spot is investigated and the influence that beam spreading works on laser aiming accuracy is analysed. The study provides a certian basis for the optimal design of compensation package of laser spot targeting deviation.Keywords：far-field;atmospheric turbulent;beam spreading;aiming deviation- 48
- |
- 7
- |
- 2
Published：2020-08-13 -
Design of Reflective Off-axis Adaptive Optics System for Human Retinal Imaging
Abstract：Abstract: In this paper, an adaptive optics (AO) systems for retinal imaging was presented, which was operated on open-loop and two-wavelength mode. The system adopted a Shark-Hartmann wavefront senser (SHWS) and liquid crystal spatial light modulator to detect and correct the wavefront aberrations respectively. 790nm near infrared was used for the wavefront detection, and 570nm visible light was used for retinal imaging. To enhance the energy-utilizing rate and avoid the chromatic aberrations, the reflective off-axis system was used. The optical system also was simulated and analyzed with ZEMAX. The result showed that the optical system was good, and could achieve the diffractive limited resolution at the designing resolution 50 lp/mm.Keywords：adaptive optics;retinal imaging;liquid crystal spatial light modulator;open-loop- 46
- |
- 6
- |
- 3
Published：2020-08-13 -
Application of active disturbances rejection control technique in satellite attitude simulation system
Abstract：Established the high-precision satellite attitude simulation system for ground-based optical communication experiment. For the features satellite trajectory, design an improved auto-disturbance-rejection control algorithm. First, introduced the characteristics and principle of auto disturbance rejection control technology. Then, proposed the improved servo algorithm, added selective integration item for ADRC algorithm. To satisfy ± 10" dynamic error requirements of system, designed multi threshold non-linear function, and then added state determine module to change non-linear function parameters in real time. At the same time, given the setting principle of the algorithm parameters. Then, based on the open servo functions of controller, the realization of the method and process was design for improved ADRC algorithm. The experimental results showed that? the dynamics following error of tracking ramp signal was ± 6 ", the system had a good capacity for acceleration and deceleration. By contrast, in the satellite attitude trajectory tracking, the auto-disturbance-rejection control of anti-interference ability is superior to PID, and the following error was ± 7 ". Auto disturbance rejection control algorithm met the requirements of high-precision attitude simulation and also had stability and strong anti-interference ability.Keywords：Attitude simulation;Auto-disturbance-rejection;Open servo;Non-linear function;Parameter setting- 30
- |
- 6
- |
- 14
Published：2020-08-13 -
Design of a test system for motion image of the space TDICCD camera
Abstract：Design and implementation of a test system for dynamical image of TDICCD (time delay and integration charge coupled devices) camera in space was presented. The system designed in this paper simulated the ground image motion relative to the space aerocraft, to validate the capability of image speed match and the quality of dynamical image of TDICCD camera. The design adopted a precision table and a drift table to simulate the motion around the earth and the drift motion in different latitude due to rotation of earth, of the aerocraft. The precision table was drived by permanent magnet torgue motor and made use of phase locked loop serve-control strategy. The drift table was drived by stepping motor and its average rotate speed was 0.02°/s. The experimental results showed that steady speed error reached 0.0297% and trace precision of draft angle was better than ±5′. The precision of the system designed was met the test requirement for dynamical image of TDICCD camera. This scheme has been applied in development of a certain space visible light camera.Keywords：TDICCD camera;dynamic object;servo-system;phase locked control;fixed-speed with high percision- 42
- |
- 8
- |
- 12
Published：2020-08-13 -
Effects of Cone-Shaped Error of Big Plane Wheel’s Grinding Face on Gear Helix Deviations
Abstract：The total helix deviation is one of mandatory inspection items in gear evaluation. Out of development of ultra precision master gear, taking Y7125 grinder as an example, effects of the cone–shaped error of grinding face on the helix deviations was derived. The results show that the minimum effective bearing width has little effect on gear helix form deviation; however, as the increase in gear width, the effect of the cone –shaped error on gear helix form deviation will significantly increase and the cone–shaped error can make curve of gear helix deviation be in arc-shaped and the crowns of arc vary from dedendum to addendum. Finally, the above conclusions are verified by gear grinding experiment and precision measurement.Keywords：master gear;big plane wheel;cone–shaped error of grinding face;gear helix deviations;error analysis- 48
- |
- 6
- |
- 1
Published：2020-08-13 -
Precise bending technology for forming steel pipe of pipeline with JCO process
Abstract：To reduce the ellipticity of the formed pipes, the precise bending technology for forming the steel pipe with JCO process is presented based on plastic bending engineering theory and machine vision technology. By prescribing two-bend in the first bending step, the springback rule can be obtained. With the springback rule and the necessary bend angle, the better punch displacement that determines the forming angle in each bending step is calculated. In the succedent bending steps, the bending process is carried out with the better punch displacement calculated above. And the angle error in each bending step is known by comparing the actual forming angle with the necessary bend angle. By conducting compensation for the last angle error in the next bending step, each precise bending process is realized. In this machine vision system, the image processing and line detecting algorithms suitable for the image of the steel pipe end plane are proposed in this paper. A calibration method is proposed to calculate the exterior parameters of the CCD camera, which employs the equilateral triangle as the calibration board and only captures one image. A mathematical model, which converts the angle in the image into the actual forming angle, is derived. The experimental results showed that the error of measuring the forming angle was less than 0.2°and the ellipticity of the formed pipes was 1.5%. Employing the precise bending technology, the high-quality pipes can be manufactured without the worker’s operating experience.Keywords：Steel pipe of pipeline;Precise bending;machine vision;line detection;Ellipticity- 68
- |
- 8
- |
- 3
Published：2020-08-13 -
New Vibration Isolation Platform Base on High Accurate Displacement Sensor
Abstract：New vibration isolation platform was designed for keeping the precise optical instrument to work accurately. The displacement sensor which accuracy is 0.1nm was the measure apparatus. The changed value of spring was measured by displacement sensor, then the changed force of spring was calculated, then adjusted the force of electromagnet actuator according to the changed force of spring. At last the precise optical instrument was balanceable. The vibration of base was isolated. According to the analysis of theory and simulation, it could satisfy the request by applying the method of vibration isolation. This method is propitious to multilevel reduce vibration, and every vibration isolation platforms are absolute.Keywords：displacement sensor;vibration;spring;electromagnet;actuator;vibration isolation- 44
- |
- 12
- |
- 2
Published：2020-08-13 -
Study of detection surface microcracks on metal plane using ultrasound lock-in thermography
Abstract：In order to increase the efficiency of inspection using ultrasound lock-in thermography (ULT) and obtain optimal results, they are investigated which include ultrasound modulation, sequences of the thermal images processing and optimal parameters selection. The principle of ULT is represented, and theory analysis is researched. Then inspection system is developed, and experiments are carried out on a metal plane with surface microcracks. In inspection, transient sequences are collected by infrared camera during amplitude modulated ultrasonic excitation by square signal and processed using method of lock-in processing to obtain phase image and amplitude image. For given A3 steel sample, results indicate that the modulation frequency which equal to 0.5Hz should be selected; the pressure force between the sample and the ultrasonic transducer is about 0.25kN, which should be small so that the transducer just can be pressed against the sample during injection ultrasound. Moreover, the distance between the injection position and crack has few effects on inspection and appropriate injection position should be depended on specific structure of sample. Using the inspection system, reliable detection of surface microcracks (micrometer level) has to be done for a few seconds.- 47
- |
- 8
- |
- 7
Published：2020-08-13 -
The Successive Mapping Detection Method of Micro EDM Discharge State Detection
Abstract：Precise detection of the discharge states is the precondition of stable control in micro EDM. However, the frequent discharge signals distortion, instability and even mutation in micro EDM make it really difficult. To solve the difficulty, the successive mapping detection principle and method combined with the system identification and fuzzy control are proposed on the basis of analyzing traditional micro EDM discharge states detection methods. For the real-time collected gap voltage and current signals in the process, fuzzy operation is used to identify the discharge state of the sampling point and then map the sampling point discharge state value to sampling point discharge state vector. “Short rate” and “spark/arc rate” are obtained by making statistics of the vectors and fuzzy reasoning is used to identify the discharge state of each cycle. The test results show that the presented detection method is highly accurate and able to identify data and operate fast. Detection results provide feed back inputs of the system discharge states for the real-time control of the discharge process, which ensures the stability and the accuracy of the processing control system.Keywords：micro EDM;discharge state detection;fuzzy logic;successive mapping detection- 38
- |
- 7
- |
- 1
Published：2020-08-13 -
Fabrication process of ultra-high metal micro electrode array using the UV-LIGA technology
Abstract：The micro electrode array has wide used both in the micro-fabrication field and the life science field. In this paper, UV-LIGA technology was investigated to fabricate the ultra-high micro electrode array, and the micro electrochemical machining was used as an aided method to remove the SU-8 resist. During the lithography process, SU-8 mold up to 1mm thick was fabricated on the substrate. Before the electroforming process, a reverse polarity procedure was carried out to make the micro roots on the substrate, which could enhance the adhesion of the micro copper electrode array electroformed to the substrate. Using the optimized parameters: single coating; soft bake110℃/12h; post bake50℃/5min, 70℃/10min, 90℃/30min; electrochemcial machining 10V/15min et al., the micro electrode arrays up to 900μm high with different shapes were fabricated. The result indicates that UV-LIGA is an excellent method for fabricating ultra-high metal micro electrode array.Keywords：UV-LIGA;SU-8 resist;Electrochemical machining;Micro electrode array;SU-8 removal- 47
- |
- 7
- |
- 5
Published：2020-08-13 -
The method of evaluating the tracking performance using the equivalent model of tracking error
Abstract：Considering the drawback of checking and testing method indoor for the dynamic characteristic of photoelectric theodolite tracking system, a novel approach is proposed as evaluating the tracking performance of photoelectric theodolite in this paper. The equivalent mathematical model of tracking error of photoelectric theodolite is established. The equivalent sine signal is inputted to the equivalent model, and gets the output. The evaluation of tracking performance is obtained based on the statistical calculation of output. The paper gives the principle of building the equivalent model of tracking error, the identification equivalent method of model order and parameters, and the design approach of equivalent sine signal which is designed according to the theodolite checking and testing desire. Because of the dynamic characteristic of theodolite needing to inspirit fully by input signal for the accuracy parameters of model, the frequency of dynamic target is modulated continuously. The proposed equivalent model is verified by simulative and experimental studies. The estimate errors of equivalent model including average error, maximum error and standard error are 2.5872e-006°≈0°, 1.8 and 1.1″. The result shows that the equivalent model meets the needs of evaluating the tracking performance of theodolite. The accurate evaluation of tracking performance is achieved.Keywords：equivalent model of tracking error;equivalent sine;least squares estimate;error estimate- 56
- |
- 9
- |
- 4
Published：2020-08-13 -
Solving duality in pose estimation from single circle based on angular constraint
Abstract：Objective: In order to solve the duality problem in pose estimation from single circle in the machine vision, an approach based on Euclidean angular constraints is presented to identify the unique pose result and the accuracy of pose estimation method is analyzed, which provides constructive suggestion on achieving accurate pose estimation from circles based on the experiments result. Method: First, the pose of single circle can be recovered from its projection with a calibrated camera, though the result is ambiguous; then, the unique pose result is indentified based on the Euclidean angular invariant which is a prior knowledge. Finally, the accuracy of the pose result is analyzed based on the theory of error propagation. Result: Experimental results indicate that the absolute angle error of circle plane is within 0.2 degree, the relative error of position determination is within 5‰, the absolute error of reconstructed distance between lines is within 8‰. Conclusion: It can accurately identify the unique pose from the ambiguous results from a single circle, the whole calculation process is concise and feasible to perform, the result is robust and reliable as well as a high accuracy.Keywords：machine vision;Pose Estimation;duality;Angular constraint;Circle;error analysis- 46
- |
- 7
- |
- 13
Published：2020-08-13 -
Analysis on Area Matching Suitability for SAR-image Matching Aided Navigation
Abstract：Matching-area suitability for SAR images, which is one of the key technologies of scene matching aided navigation, was studied in this paper. Firstly, the problem of SAR matching-area suitability was described combined with SAR imaging process, integrated navigation course and SAR image characters. Secondly, on the purpose of decreasing geomantic distortion and elevating matching probability, several effect factors for matching-area suitability were analyzed, which including constrain conditions in application, construction of feature criterions and predicting functions. Then a multi-objective genetic optimizing based matching-area selection model was proposed to seek for scene areas with small distortion and steady, remarkable, and abundant image features. Experimental result shows that matching probability of selected best matching area is 94%, which proves the rationality of the analysis and model. The proposed method can help to choose good SAR matching areas.Keywords：SAR-image matching aided navigation;matching-area suitability;feature criterions;predicting functions;multi-objective genetic optimizing- 30
- |
- 6
- |
- 3
Published：2020-08-13 -
An Image Reconstruction Algorithm Based on weighted SVD Truncation Conjugate Gradient Algorithm for Electrical Capacitance Tomography System
Abstract：To solve the “soft-field” nature and the ill-posed problem in electrical capacitance tomography technology, on the basis of the singular value decomposition theory of the sensitivity matrix, a SVD truncation conjugate gradient weighted image reconstruction algorithm for electrical capacitance tomography system is presented, a mathematic model for this algorithm is established and its convergence characteristic is proved, and this method is applied to the image reconstruction for electrical capacitance tomography system. Experiment results and simulation data indicate that the precision of the reconstructed image is higher, the speed is faster and it is easier to implement compared with LBP algorithm and CG algorithm.Keywords：electrical capacitance tomography;image reconstruction;singular value decomposition;conjugate gradient algorithm- 83
- |
- 7
- |
- 12
Published：2020-08-13 -
Multi-focus Image Fusion Algorithm Based On Adaptive PCNN And Wavelet Transform
Abstract：A novel algorithm based on Pulse Coupled Neural Network (PCNN) and Wavelet Transform for Multi-focus image fusion was proposed. First, the two original images are decomposed by wavelet transform. Then, based on the PCNN, a fusion rule in the Wavelet domain is given. This algorithm uses the local entropy of wavelet coefficient in each frequency domain as the linking strength, so that its value can be chosen adaptively. After the processing of PCNN with the adaptive linking strength, new fire mapping images are obtained. According to the fire mapping images calculate the firing time gradient maps. The fusion coefficients are decided by the compare-selection operator with the firing time gradient maps and the fusion image is reconstructed by wavelet inverse transform. Furthermore, by this algorithm, the threshold adjusting constant is estimated by appointed iteration number. Furthermore, In order to sufficient reflect order of the firing time, the threshold adjusting constant is estimated by appointed iteration number. So after the iteration achieved, each of the wavelet coefficient is activated. Lots of experiments and comparisons with other fusion algorithms show that the method can effectively enhance the edge details and improve the spatial resolution of the image.Keywords：image fusion;Pulse-Coupled Neural Network (PCNN);wavelet transform;Local entropy;Linking strength;Fire mapping image- 48
- |
- 9
- |
- 15
Published：2020-08-13 -
Variable bandwidth kernel particle filter for optoelectronic target tracking
Abstract：Due to adoption of the kernel density estimation (KDE), kernel particle filter (KPF) is an effective method for target tracking in dynamic system with small noise. However, selection of the kernel bandwidth is a critical step in KDE. In this paper, a variable bandwidth kernel particle filter (VBKPF) based on covariance matrix is proposed. Firstly, covariance matrix of the particle sets is used to compute the coarse bandwidth and the coarse posterior probability density functions (PDFs). Then, each particle can acquire its own accurate bandwidth by adjusting the global kernel bandwidth to improve the precision of the KDE estimation. At last, to get a more effective allocation of particles, we use the variable bandwidth KDE in the VBKPF to approximate the PDFs by moving particles toward the posterior. This gives a closed-form expression of the true distribution. Experimental results show that the proposed VBKPF performs better than the standard particle filter, unscented particle filter and the kernel particle filter both in efficiency and estimation precision of the optoelectronic target tracking system.Keywords：particle filter;Kernel density estimation;Mean-shift- 54
- |
- 6
- |
- 2
Published：2020-08-13 -
Rényi entropy-based saliency map generation and target detection
Abstract：The performance of automatic target detection is affected heavily by complex and unknown scene of natural ground images. In the natural ground images, the Rényi entropy and its occurrence probability, which is calculated through the pseudo Wigner-Ville distribution (PWVD) using two dimension window, has a statistical property based on exponential function. And the statistical property will be changed by the appearing of man-made targets. On that basis, a novel method of saliency map generation and target detection based on Rényi entropy is proposed. At first, the image of Rényi entropy is smoothed by the average filter. Then, by the subtraction of fore-and-aft filter images, the image of residual Rényi entropy can be obtained. The saliency map can be obtained by Gaussian filter. Finally, target detection is completed when the saliency map is segmented by a simple and convenient threshold method. Experimental results demonstrate our method can detect the military targets from complex ground scene effectively. In the test of 14 targets in 8 images, the detection probability and false alarm probability of our method are 100% and not more than 7.1% respectively.Keywords：pseudo Wigner-Ville distribution;Rényi entropy;saliency map;Target detection- 30
- |
- 5
- |
- 1
Published：2020-08-13 -
The emulational device for opto-electric detecting based on LabVIEW and c language
Abstract：LabVIEW has the advantage of high efficiency on development, all kinds of functions and so on. But it is not as good as the C language on hardware driving. Take a emulational device for opto-electric detecting in Hyper Spectral Imager for example, In order to resolve the technical difficulties on hardware interrupt in LabVIEW, the interrupt service routine was programmed by C language, the C program was changed to dynamic link library in the visual C++ and the library function node was called in LabVIEW. The control and test on opto-electric devices were achieved by 1553B bus communication. At the same time, a kind of method on improving transmission real time characteristic of 1553B was given in this paper, which bases on improved Rate-Monotonic Scheduling algorithm and K昉earson chi-square. In the condition of transmitting several periodic and aperiodic messages, the experimental results show that the method has good performance on real time characteristic and reliability, and the system has good expansibility.Keywords：virtual instrument;Chi-square Test;Rate-Monotonic Scheduling;mixed programming- 27
- |
- 6
- |
- 5
Published：2020-08-13 -
A Method of Energy Accumulation in Infrared Point Target Detection
Abstract：There are some drawbacks in target detection using the technique of energy accumulation based on traditional dynamic programming algorithm (DPA). Those drawbacks include large energy distraction, slow detection speed and low detection probability. For solving the problems, an energy accumulation method of IR point target detection based on DPA is proposed. The weighted information entropy (WIE) attenuation factor and directional weights are imported into DPA recursive formula. WIE can reflect the targets’ moving information. When target exists in the searching window, accumulated energy decays a few which guarantees the larger energy accumulation and less energy distraction in the area of target track; Directional weights can reflect the moving direction of target and make the energy accumulate toward to the moving direction with a large probability. The experiment adopts 12 frames of image sequences with the average SNR of 2.1725. Compared with traditional DPA algorithm, by using the method proposed in this paper, accumulated energy reaches to the detecting threshold in the 5th frame with the Pd of 0.915. While using the traditional method, energy reaches to the threshold in the 9th frame with the Pd of 0.956. Results show that the method is able to reduce the area of energy distraction tremendously and increase the detecting probability and speed obviously.Keywords：target detection;dynamic programming;energy accumulation;WIE attenuation factor;directional weights- 54
- |
- 8
- |
- 18
Published：2020-08-13 -
4f System Image Denoising in NSCT Domain Based On the Continuity of Image Texture*
Abstract：4f system has the characters of noise and low-pass, to remove the noise and protect the image texture of its output images, a method is proposed. Different with the classic hard threshold denoise method in NSCT domain, it adopts a smaller threshold to remove the small amplitude noise to protect the image detail better and protrude the remanent big amplitude noise, then uses the continuity of image texture to remove the large amplitude isolated noise from the consecutive image detail in the high-frequency sub-band images. Eventually the noise is removed and the image detail is protected in the same time. Experiments show that the method can reach the same degree with classic methods in denoising, and is better than classic method in protecting image detail in view of vision and numerical judgment standard. It is more suitable for the situation as the 4f system which needs protect the image detail extraordinarily.Keywords：information optics;nonsubsampled contourlet transform;Image denoising;4f system- 36
- |
- 4
- |
- 1
Published：2020-08-13 -
Magnetic resonance image denoising in dual-tree contourlet transform domain
Abstract：In order to improve the quality of the Magnetic Resonance (MR) image, a denoising algorithm for MR image using Dual-Tree Contourlet (DT-Contourlet) transform is proposed. First, the distribution model of the noise in MR image is investigated, and that such noise obeys Rician distribution; based on this, a new method to estimate the noise parameters of the squared magnitude MR image is derived. Then, the pyramidal dual-tree directional filter banks of DT-Contourlet is analyzed to show that DT-Contourlet maintains the flexibility direction selectivity of the contourlet transform, and overcomes the limitation of the contourlet which namely lack of shift invariance．After that, in the DT-contourlet domain, by calculating the Variance Homogeneity Measurement (VHM), the locally adaptive window is determined to compute the shrinkage factor to shrink the DT-contourlet coefficients of the squared magnitude MR image. Finally, the denoising algorithm to MR image is implemented via the inverse DT-Contourlet transform. Experimental results show that the performance of the proposed algorithm is superior to the traditional algorithms in terms of the Peak Signal to Noise Ratio (PSNR); for simulated MR images with different noise variances, the new algorithm outperforms wavelet-based and contourlet-based algorithms by 2.13dB and 0.91dB averagely. As for visual quality, the proposed algorithm could reduce the noise in MR image effectively and retain more details simultaneously.Keywords：Magnetic resonance image;DT-Contourlet transform;Estimate the noise parameters;image denoising- 46
- |
- 6
- |
- 2
Published：2020-08-13 -
An improved mean shift based IR target tracking algorithm
Abstract：In order to enhance the robustness of IR target tracking under complex background, an improved Mean Shift tracking algorithm is proposed. This algorithm combines the advantage of gradient matched searching strategy based on mean shift with the robustness of the tracking algorithm based on featutes classification，and likelihood ratio weighted kernel histogram target representing model is presented. In improved model the likelihood ratio of gray level feature of target and local background is regarded as a weighted value of original kernel histogram, and then the robustness of tracking the IR target with low contrast is enhanced by increasing the shift weighted value of target gray level in the form of mean shift tracking, and background interference is suppressed effectively. Adaptive performance of the algorithm is improved via proposing the discrimination criterion of model updating based on tracking complexity estimation under target occlusion. The validity of new algorithm is verified by the actual experiment.Keywords：information processing technology;IR target tracking;mean shift;likelihood ratio- 68
- |
- 7
- |
- 6
Published：2020-08-13
Article
Loading...
0