Chinese Version Light学术出版中心
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Issue 5 ， 2009
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Demodulation System for Fiber Grating Sensors based on Fiber Loop Mirror
Abstract：A novel demodulation scheme for fiber Bragg grating sensors based on polarization fiber loop mirror is proposed in this paper. The theoretical analysis model is established. The impact characteristics to the demodulation decision from the fabric parameters of the polarization maintaining fiber loop mirror are researched and the numeric value simulation is processed. The beam path system is established. Moreover, the circuit model the software for measuring the parameters and monitoring the demodulation system based on LabVIEW which can eliminate the impact from the fabric parameter error are both designed. The sensor detection experiment is processed and the result is consistent with the theoretical analysis. The system has high stability, high detection precision and strong applicability. It has a very important significance in the application of the fiber grating sensor.Keywords：sensor demodulation;fiber loop mirror;LabVIEW- 59
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Published：2020-08-13 -
Study on removal function based on computer controlled grinding SiC mirror with fixed abrasive
Abstract：The paper describes a brand-new technology which is called fixed abrasive technology. The removal function model of multi-pellets polishing pad is achieved and it is based on the removal function theory of planet motion .The parameters of model have been optimized through the approaching factor,and curve rms distance . The experiment is carried out under these optimized parameters. Through the comparison of theoretical model and experimental results: the warp between theoretical maximum removal rate and experiment is , the ratio is 5.58% . The distance warp between theoretical removal function curve and experimental curve is , ratio is 7.01%. The veracity of theoretical model is verified through experimental results. So it has good prediction for the fabrication result of fixed abrasive and the fixed abrasive technology has great foreground in SiC mirror precision fabrication field.Keywords：fixed abrasive;pellet;SiC;removal function- 51
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Published：2020-08-13 -
Calibration method for line structured light sensor based on perspective-three-point model
Abstract：A calibration method based on perspective-three-point was proposed to solve the calibration problems in line structured light sensor system such as requirement of high accuracy calibration model, complicate calibration procedure and so on. The calibration model used a coplanar reference target with three collinear and known distance points. The line across the three points intersected the laser stripe at a point that was called as the calibration point. The calibration point coordinates in the camera coordinate system can be calculated by using the imaging information of the three points and that of the light stripe on the camera’s image plane. The spatial pose between camera and light plane can be calibrated by moving the reference plane at several arbitrary places in the sensor range. Experiments show that the sensor can attain relative accuracy about 0.8%.The method decreased the cost of calibration equipment, and needn’t calculate the transformation matrix between different coordinate systems. The method is simple and flexible, and can satisfy the precision requirementsKeywords：Line structured light;calibration;Light plane;Perspective-three-point- 34
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Published：2020-08-13 -
The application for the system to characterize the retardation films at different wavelength
Abstract：The paper reported a method to characterize the retardance of retardation films at different wavelength. The system is based on the method of rotation of quarter wave-plate. A spectrometer was sued as the light source ,color filters and a photodetector. We measured some samples using the system, analysed the measurement data, and obtained the spectrum characteristic of the retardation films. According to the theory of the system, the variation of the light source and other errors related to light intensity are not so critical for the measurement in this system. Furthermore, some quarter wave-plate’s affect for the other wavelength is very little, so the retardance is determined in a high accuracy and in a high repeatability. In principle, any retardance within the system accuracy can be measured.- 30
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Published：2020-08-13 -
An effective method to improve the performance of the surface modification of the space used RB-SiC mirror
Abstract：The technical method for the surface modification is improved according to the material speciality of RB-SiC witch is to fulfil the application requirement for high surface quality of the space used,large scale and complicated light weighted RB-SiC mirror.It is to use the high energy kaufman ion source for IBAD;to carbonize the substrate and then prepare a carbon buffer layer befor the deposition of Si coating for surface modification.The testing re-sults show that the coating grows more compact and uniformity contrast to the method of simply using Hall ion source.So the characteristic for polishing is nicer.After the surface modification the surface roughness(rms) reduce to 0.635nm witch has reached the level of S-SiC;the surface reflectance is obviously enhanced and is correspond to that of fine polished zerodur glass.The conclusion can be drawn that this technical method for the surface modification of RB-SiC mirror is quite reasonable and effective.Keywords：carbonlization;RB-SiC;SiC mirror;surface modification- 37
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Published：2020-08-13 -
External resonator YVO4 crystal Raman laser
Abstract：YVO4 crystals with high optical quality were grown by Czochralski pulling method. The largest sizes were 28mm×40mm, and the weight was 126g. Using a mode-locked Nd:YAG laser with pulse width of 40ps as the pump source, we researched the Raman output properties of a YVO4 crystal in an external resonator. The total conversion efficiency for multi-wavelengths output reached 51.4%, and the largest output energy was 2.21mJ. The highest conversion efficiency for the first Stocks Raman output of 1175nm was 32%, and the largest output energy was 0.57mJ. The conversion efficiency for the second Stocks Raman output of 1325nm was 12.3%, and the largest output energy was 0.36mJ.Keywords：stimulated Raman scattering;external resonator;YVO4 crystal;Stocks laser;conversion efficiency- 26
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Published：2020-08-13 -
A Method of Enhancing Accuracy of Biochemical Analyzer by Uniforming Different Integral Time Data
Abstract：In order to improve the performance of Biochemical Analyzer, one uniform integral time method for CCD data acquisition was presented in the paper. Different integral time data transformation was calculated based on the PDA drive program and the photoelectricity transformation principle; the linearity region of biochemical Analyzer was confirmed according to both performance parameter and experiments; different integral time dark current was confirmed according to the experiments and was removed from original spectrum. The experiment proved that the precision has been improved for 25% by using the uniform integral time method, further more, the dynamic range has been enlarged and the procedure has been simplified.Keywords：PDA;CCD;Biochemical Analyze;integral time- 43
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Published：2020-08-13 -
Three-component Photoelastic Waveguide Accelerometer Based on Photoelastic Effect
Abstract：In order to realize a high accuracy seismic exploration in the high electro-magnetic area , the three-component photoelastic waveguide accelerometer is designed. First, based on the photoelastic effect, the integrated optical circuit is designed to measure the three-orthogonal components of acceleration. The combined three-component simple harmonic vibrator is designed to reduce the cross-talk of the acceleration component. Then, based on the variation law of LiNbO3 waveguide phase, the cross-axise sensitivity and transverse sensitivity ratio（TSR）are analysed. Finally , The total structure of the sensor is designed. Experimental results indicate that the sensor’s natural frequency is 3500 Hz; the transverse sensitivity ratio is 0.11%. It can satisfy the sensor requirements of high ccuracy seismic exploration.Keywords：integrated optics;accelerometer;photoelastic effect;LiNbO3 optical waveguide- 35
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Published：2020-08-13 -
The compensating effect of blazed wavelength to grating anomalies in the design of broadband metallic diffraction gratings
Abstract：A new design method of broadband metallic diffraction gratings with single blaze surface, which has good applicability and implement in technology, is given. Basing on the principles of two types of grating anomalies, Rayleigh type and resonance type, the occurrence conditions of them are discussed. On the base of electromagnetic theory of gratings, the blaze character of diffraction efficiency both for TE and TM mode are numerically analyzed. It is found that the relationships between grating anomalies, the spectrum band of gratings and blazed wavelength. An idea of designing diffraction gratings is brought, which compensates Rayleigh anomaly or resonance anomaly with the first blazed wavelength of TM mode. The compensating effect of the first blazed wavelength of TM mode to Rayleigh anomaly is only the limitation case to resonance anomaly. The design examples of broadband metallic gratings with different groove density, which are applied in UV-visible, near infrared and infrared spectrometers, are given. The compensating effect method is better than the traditional design method of broadband metallic grating, whether in theory design or technology process, it makes the diffraction efficiencies of broadband metallic gratings to be over 40% in different spectrum band.- 41
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Published：2020-08-13 -
Analysis of Fresnel-zone-plate Diffraction in Scanning Holography
Abstract：The diffraction of Fresnel-zone-plate (FZP) functioned as coded aperture is studied through numerical calculation and experimental measurement. Considering the lens as phase modulator, the equivalent distance at which the same distribution of diffraction intensity is generated with lens is obtained by comparing that without lens. The virtual Fresnel diffraction plane is introduced accordingly. In order to analyze the diffraction of FZP quantitatively, a critical diffraction distance is thus defined. The influences of focal length of lens, fringe number and radius of FZP on diffraction are measured in experiments, which testifies the calculation. Moreover, the diffraction with incidence of spherical wave is discussed. In the end, some suggestions on the design of FZP, the focal length of lens and the distance between an object and the lens are proposed.- 42
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Published：2020-08-13 -
Tunable acousto-optically Q-switched CO2 laser
Abstract：In this paper, a miniature CO2 laser that adopting acousto-optically Q-switched and grating tuned approaches is described, which pulse repetition frequency (PRF) is 1 Hz~50 kHz and the tuned wavelength range is 9.2 μm～10.8 μm. The pulse width of 180 ns and the peak power of 4062 W have been obtained at the wavelength of 10.6 μm when PRF is 1 kHz. The calculated results of laser rate equations are in good agreement with the experimental values.Keywords：laser technology;CO2 laser;acousto-optically Q-switched;grating tuned- 38
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Published：2020-08-13 -
Study on focalizing of a fudus camera for a non- mydriatic pupil
Abstract：Two deflection-angle prisms were used to finely focalize the fundus of an eye when the fundus was observed in the dark. A slit mark was projected onto the fundus. Light transmited in two different directions through the slit mark because of the bending of the deflection-angle prisms. The slit mark was broken into two slit marks. When the fundus was in focus, these two broken slit marks would be in a line. These two slit marks would be taken apart when the fundus was out of focus. The separated distance and direction of these two slit marks were depended on the state of the defocus. Experiment showed that it was simple and had high precision when one judged focus states basing upon whether these two slit marks were in a line.Keywords：non-mydriasis;fundus camera;finely focalize- 42
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Published：2020-08-13 -
Design of mirror profile for panoramic imaging system using multi-populations genetic algorithms
Abstract：A design method of aspherical surface for panoramic imaging system with two mirrors using multi-populations genetic algorithms is proposed. Astigmatism induced by mirrors may significantly compromise the image resolution. To solve this problem, we induced algebraic expression of astigmatism in panoramic imager based on generalized Coddington equation and the theory of geometric optics. Then, we proposed an optimization process for mirror profile design to eliminate astigmatism and provide purposely-designed projection formula with aid of MPGA. A series of polynomial expressions of aspherical surfaces were obtained and procedures of the design were presented. In order to facilitate raytracing and aberration calculation, even asphere surface model was obtained by using of hybrid schemes combining MPGA and damped least squares. Finally, a prototype of the catadioptric panoramic imager had developed and panoramic ring images were obtained.- 44
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Published：2020-08-13 -
Design of an Embedded Virtual Dynamical Signal Analyzer
Abstract：In order to provide a design tool for the photoelectronic tracking system under the remote control, an embedded virtual dynamical signal analyzer is established, and its applied algorithms such as system identification and etc are investigated. Based on a the platform of a photoelectronic tracking system, and integrating the concept of the virtual device and the embedded technology, the idea of the embedded virtual dynamical signal analyzer(EVDSA) is presented and the system infrastructure is established. The software of the three layers of the system infrastructure is designed individually and especially the software of the application layer which is based on the system identification technology. The current loop and the speed loop of the photoelectronic tracking system are tested by the EVDSA and the experimental results show that the photoelectronic tracking system meets the design demand: the bandwidth of the current loop is 266.05Hz, and the bandwidth of the speed loop is 20.3Hz, and the accuracy and the practicability of the virtual device. It can satisfy the design tool requirements of precise, convenient and rapid speed, as well as improving the design level and efficiency of the photoelectronic tracking system.Keywords：photoelectronic tracking system;Virtual device;system identification;DFT- 36
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Published：2020-08-13 -
Automatic-leveling system for base-plane of large-size photoelectric equipment
Abstract：There are three mechanical supporting points of the large-size photoelectric equipment, base-plane’s obliquity come from the obliquity-sensor which fixed on pedestal of the photoelectric equipment, convert the obliquity to mechanical supporting’s elongate， drive the mechanical supporting level the base-plane. Introduced the reasons for choice three supporting points and mechanical supporting, designed the mechanical supporting and the entire transmission system, showed the drive circuit and automatic-leveling arithmetic. Automatic-leveling experiment indicated that the automatic-leveling system not only achieved the target precision, but also shorten the time of photoelectric equipment’s prepared to work.Keywords：mechanical supporting;limited-place;leveling-garithmetic- 31
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Published：2020-08-13 -
study on high precision time interval measurement in pulsed laser ranging
Abstract：The high accuracy time interval measurement is a key technique to pulsed laser ranging. Therefore, a new high precision time interval measurement method is proposed. Field-Programmable Gate Arrays (FPGA) is used to implement the multi-level time interval measurement. The coarse time measurement is realized by the coarse counter to guarantee large dynamic range. The PLL unit in an FPGA is used to generate the N clock pulses with the same frequency and uniform distribution phase as counting clock. Based on the equal precision frequency measuring, the resolution of the time conversion is improved to Tclk/N. A chain of the latch flip-flops is used to measure the fine time interval. The problem of the traditional multi-phase sampling approach that the phase shift resolution is decreased as the increased frequency is solved. The fine resolution can be achieved with limited delay lines while no need to increase the counting clock. The test results show that the proposed method can realize wide dynamic range, small conversion time and high resolution.Keywords：laser ranging;time interval measurement;multi-phase sampler;delay line- 54
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Published：2020-08-13 -
Design on focusing mechanism of space tridimensional mapping camera
Abstract：the CCD plane of the space tridimensional mapping camera will be brought displacement, to some extent, under the condition of space environment and vibration、 impact when satellite is launching. In order to meet the requirement of image quality of the camera and complete behind mapping mission, the changed position of CCD plane should be equalized. For a focusing mechanism which based on cam is designed, focusing scheme and focusing quantity are confirmed, Analysis of transmission error and validated test indicated that the error of this focusing mechanism was ±1.71 μm；linearity of CCD plane, X direction was 11.2〞、Y direction was 11.8〞; circumaxis angle of CCD plane was 4.7〞.The result of precision analysis indicated that the focusing mechanism is meet to the requirement of the user.Keywords：tridimensional mapping camera;CCD plane;focusing mechanism- 36
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Published：2020-08-13 -
Approach for Accurately Extracting the Full Resolution Centers of Structured Light Stripe
Abstract：Effect of extracting the center of structured light stripe directly affects the precision and resolutions of 3D coordinate measure. This paper firstly extracted initial centers of the light stripe with the threshold algorithm, secondly, calculated the normal direction at the initial point of the stripe based on image gray grads, finally, accurately gained the energy centers along the normal direction of the stripe. Experiments show that the approach can get full resolution centers, improves the precision of stripe centers, and avoid min density for max curvature surface of the measured object.- 27
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Published：2020-08-13 -
Research on the surface texture evaluation mean line based on ISO5436-2
Abstract：For the surface texture evaluation, such as for the parameters of roughness profile, to obtain the evaluation datum, namely mean line for 2 dimensional parameters, is very important besides the interpretation to the parameters definition. In order to appraise the whole performance of the instruments, ISO TC213 proposed Standard ISO 5436-2 of software measurement standard for surface texture. It includes standard data and software for the application of verifying the software performance. Based on Standard ISO 5436-2, the evaluation datum obtained form different theories are researched. They are mean line given by Gaussian filter, Least squares mean lines with order 1 and 2. The standard data are used to calculate the arithmetical mean deviation of the assessed profile. The results show that the roughness parameters almost have no difference based on three mean lineKeywords：Research on the surface texture evaluation mean line based on ISO5436-2- 33
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Published：2020-08-13 -
Experiment of electricity generating capacity with the piezoelectric unimorph cantilever
Abstract：In order to measure and study the electricity generating performance of the piezoelectric ceramics(PEC), a measuring system for the electricity generating capacity of the PEC was developed. A piezoelectric unimorph cantilever was designed and the effect of optimal thickness ratios(ORT) for the piezoelectric unimorph cantilever analyzed by finite element analysis(FEM). The results show that the output voltage and power is maximal at the resonance frequency. The ORT of the piezoelectric unimorph cantilever is 0.5 by FEM. It was consistent with the experimental results. The output voltage of the piezoelectric cantilevers increases with the resistive load increased. The voltage approaches 5.4V when the resistive load is 50 . Nevertheless, the electrical power decreases when the load resistance is further increased. A maximal output power of about 1.18 mW can be obtained from the piezoelectric cantilever at the resonance frequency across a resistive load of 10 , this power level is already enough for some wireless communication systems.Keywords：piezoelectric unimorph cantilever;electrical energy generation;optimal thickness ratios;finite element analysis(FEM)- 31
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Published：2020-08-13 -
Investigation on design methodology of double-chamber piezo-pump
Abstract：Single chamber piezo-pump is limit applied in many fields because lack of self-priming and bubble-tolerant, it is an efficient way that adopt multi-chamber structure to enhance the performance of piezo-pump. The analysis result about changing process of volume and pressure of chamber shows that double-chamber serial piezo-pump only can be tandem driven, and double-chamber parallel piezo-pump only can be parallel driven respectively. The experiment results indicate that the maximum flow of double-chamber serial pump is 1150ml/min (sine wave voltage is of 200v, frequency is of 152Hz) and that of double-chamber parallel pump is 640ml/min (sine wave voltage is of 140v, frequency is of 220Hz), and the efficiency and performance is enhanced as chamber in tandem structure.Keywords：piezoelectric vibrator;double-chamber piezo-pump;serial piezo-pump;parallel piezo-pump- 32
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Published：2020-08-13 -
Cutting Force and Chip Deformation in Micro-Cutting Process
Abstract：Through the analyses of the mechanism of the machined surface formation, the formation of machined surface and the deformation coefficient in micro machining are analyzed with consideration of the existence of rounded edge radius. The cutting force and chip deformation are presented theoretically. Moreover, the factors such as the cutting speed, feed, cutting depth, tool material, and workpiece material which affect the cutting force and surface formation are revealed based on the experiments process. In micro machining, the deformation coefficient is more than that of in macro machining. To reduce the rounded edge radius will reduce the contact length between the flank face and the workpiece, the deformation of uncut metal under the tool edge, and it is benefit to obtain a desirable finish of the machined surface.- 39
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Published：2020-08-13 -
A theoretic model for TWEO pumping microflow and experimental research
Abstract：To research traveling wave electroosmotic(TWEO) driving microflow, simulation and experimental analysis for TWEO flow in a closed microchannel are explored. From the charge distribution in the double electric layer, a nonlinear model for TWEO pumping microflow is presented. Through solving the electric field and velocity field problems, the velocity field simulation is presented in a closed microchannel. Contrasting with the experimental result, the theory for the model is verified. The velocities on the 2/3 height in the microchannel are showed in simulations and experiments, the results show the relation between velocity and frequency satisfy normal distribution. These results offer a basis for further researching TWEO pumping microflow and it application in lab on a chip.Keywords：traveling wave electricosmotic;theoretic model;pumping microflow;simulation- 48
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Published：2020-08-13 -
The study of radial tire air bubble defect double-exposure digital hologram inspection method
Abstract：A double-exposure digital holography interferometry is proposed and firstly used into the air bubble defect detection of radial tire. A series of digital holograms are recorded during the tire deforming process, the reconstructed images of which are obtained in the computer. After being contrasted the interference fringes between the deformed wave-front and undeformed wave-front of the defect tire and regular tire, the detection rules has been found. The results show that the double-exposure digital holography interference fringes, which lie in the air bubble defect area, have special feature, the proposed method can be used in tire defect diction with high precision.Keywords：digital hologram;radial tire;defect inspection- 56
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Published：2020-08-13 -
Digital image stabilization algorithm based on particle filter
Abstract：A digital image stabilization algorithm for image sequence based on particle filter was present. Firstly, the corners are extracted using improved sobel operator, then the mapping relationship is established between ima- ges and global motion vectors are obtained adopting least-squares solution using affine transformation model. Las- tly, correctional vectors are acquired using particle filtering and video frames are correctly adjusted. Experimental results show the stabilization algorithm is effective and robust. The correct vectors of camera are reserved and noi- se is eliminated.Keywords：particle filter;corner detection;global motion estimation;digital image stabilization- 52
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Published：2020-08-13 -
Modified Hough Transform for Line Detection in Traffic Sign Image
Abstract：Line in traffic sign image is a significant feature for traffic sign recognition. A modified Hough transform is proposed for line detection in traffic sign image. There exist some drawbacks in the existing Hough transform, such as peak diffusion in parameter space, heavy burden of computational complexity, and massive storage requirement. In this paper an adaptive many-to-many mapping scheme is proposed to overcome these drawbacks. With the new mapping scheme, the peak corresponding to an image line does not spread around in parameter space and is insensitive to parameter quantization, so the threshold can be selected conveniently. These characteristics are very helpful to accurately detect the parameter of a line in image. Experimental results reveal that the proposed method is more efficient for extracting the line in traffic sign image at the cost of an acceptable running time.Keywords：traffic sign image;Hough transform;line detection;“Many-To-Many” mapping scheme- 61
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Published：2020-08-13 -
Space-variant Blurred Image Restoration Based on the Segmentation According to Pixel’s Motion-blur Character
Abstract：Analyzing a kind of space-variant blurred image which was resulted from moving target shot by moving camera, the article presented a method of space-variant blurred image restoration based on image segmentation according to pixel’s motion-blur character. Because of the convolution process of motion blur, the pixels of observed image’s target and background will be displaced and piled up and will produce two superposition regions. As a result, the neighboring pixels in the superposition regions will have similar grey level change. According to the feature, the method could detect the target’s blurred edge of superposition region. And canny operator was recurred to detect the target edge which parallels the motion blur direction. Then the segmentation process obtained the whole target image which has the character of integral convolution between motion blur and real target image. At last, the target image restored by adding zeros and deconvolution algorithms. The practical restoration result indicated that the approach can effectively solve the kind of problem of space-variant motion blurred image restoration.Keywords：image restoration;space-variant blur;image segmentation;motion blur- 43
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Published：2020-08-13 -
3-D Measurement of free-form surfaces with stereo vision based on vanishing-point calibration
Abstract：The nonlinear calibration for camera was applied to two view-point 3D reconstruct system using vanishing-point. The image features of a free-form surface were enhanced by means of projecting arrays of dots. An array coded algorithm of direction and distance restricted was presented for projecting dots. First, get an original matching point and four original matching directions automatically according to the positions of red points. Then, all other white dots viewed both in two images can be coded by the proposed method and the images in two directions can be matched automatically. The experiments of 3D measurement and reconstruction of plaster model indicated that a sub-pixel precision can be got by using the algorithm of nonlinear vanishing-point calibration and the array code method based on direction and distance restricted can coding the projective point on picture rightly and can performs matching effectively between two images.- 52
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Published：2020-08-13 -
Design of Assembly Modular for OBS Edge Node
Abstract：In order to improve the assembly performance of optical burst switching (OBS) network, the assembly modular for the edge node of OBS is studied in this paper and the design scheme of a novel assembly controller (AC) is proposed. By means of introducing the feedback of BDP size, the modular proposed in this paper makes the time-threshold based modular a closed-loop system, which is different from former assembly modules that can be considered as an open-loop system. The novel modular measures the network traffic flow and chooses a suitable timer-threshold for the timer according to the control curve. Moreover, the control curve can be modified according to the BDP size feedback. Simulation results show that the novel modular can improve the distribution of BDP size by 4.95% compared with the time-threshold based modular. In addition, the assembly delay can also be improved by 15％. Therefore, the novel modular not only can adjust the timer threshold according to the traffic flow, but also can control the distribution of Burst size.- 27
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Published：2020-08-13 -
Design of an inspecting system for measuring the centroid and centroidal deviation of bullets with high accuracy
Abstract：Centroid and centroidal deviation of bullets are important design parameters of bullets, and the measurement precise of these parameters is quite necessary to improve production quality and shooting veracity. In order to improve the measuring accuracy and efficiency, this paper presents the working principle and the relevant calculation formulae and measuring equipment for measuring the centroid and centroidal deviation of bullets based on three point method. The main factors affecting precision are discussed, multiple measuring platform with automatic leveling and column structure autorotation of 90°is put forward in the paper. The given experimental results show that these methods can improve greatly measuring precision and efficiency and satisfy the requirement for measuring the centroid and centroidal deviation of bullets with high accuracy. The equipment has wide measurement range, low manufacture cost and broad appliance and development prospect.Keywords：bullet;centroid and centroidal deviation;Three point method;error analysis- 30
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Published：2020-08-13 -
A parallel image restoration and super-resolution processing system based on the PPF and Cluster architecture
Abstract：A parallel processing system was developed to realize real-time restoration and super-resolution processing of huge amount of large size images after investigating its technical scheme, working principle, key algorithms, hardware architecture, parallel technology and et al. First, the system’s working principle and key algorithms of deblur, denoise, super-resolution were presented based on the technical scheme. After analyzing and comparing the two architectures of DSP and Cluster, employ principle of the Cluster’s equipments was given. It is concluded that Cluster is more suited for large scale parallel processing. Then a parallel algorithm model based on the PPF architecture and multi-layer parallel optimization technology based on the hybrid architecture of MPI+OpenMP were introduced. Finally, experiments and analyses were made on processing effect and speed of DSP and computer, following by scale and performance prediction of system. How to choice the number of processes was also discussed. Experimental results show that the parallel system can reduce run time from 2700s to 29.39s, making images improved apparently in sharpness, contrast and resolution. It can satisfy our application and have a universal property。Keywords：image restoration;super-resolution;DSP;Cluster;parallelism- 70
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Published：2020-08-13 -
The restoration of aerial images degraded by multiple blurred
Abstract：An algorithm is proposed to restore the images, simultaneously degraded by multiple blurred during aerial imaging. Based on the analysis of the physical model of multiple blurred, the multiple blurred can be restored by restoring the every sub-blurred step by step. To reduce the accumulating of calculation error during the restoration for multiple blurred images, the point spread functions (PSFs) of each space-invariant blur in the multiple blurred are combined by convolving all the linear PSFs together. For that, the multiple blurred made up of the space-invariant blurs can be eliminated by a deconvolution restoration. Through analysis the error noise arising during the image restoration, the Wiener filter is applied to suppress the error noise for the multiple blurred consist of space-variant blur. What’s more, the application of Wiener filter can increase the PSNR of the restored image by 7.76dB. The experiment results show that the PSNR of the image, restored by the proposed algorithm based on the PSFs combination, can reach 28.09 which ensures the restoration quality can be acceptable.Keywords：aerial image;multiple blurred;space-invariant blur;space-variant blur- 40
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Published：2020-08-13 -
Local Adaptive Image Denoising based on Double-Density Dual-Tree Complex Wavelet
Abstract：An efficient local adaptive image denoising algorithm based on the double-density dual-tree complex wavelet transform (DD-DT CWT) is proposed. First, The principles and characteristics of DD-DT CWT are analyzed and the derivation of bivariate shrinkage function(BSF) is given. DD-DT CWT is implemented by applying four 2-D double-density DWTs in parallel to the noise images with distinct filter sets for the rows and columns. According to the statistical properties of wavelet coefficients and the dependency of inter-level and intra-level coefficients, the bivariate shrinkage function with local variance estimation is adopted to processing wavelet coefficients. The denoised images are synthesized using the wavelet coefficients after processing. Finally, The proposed algorithm is tested on some gray and color noisy images. Experimental results show that, compared with the noise images, the Peak Signal-to-Noise Ratio (PSNR) gains reach 11.72dB, Mean Structural Similarity (MSSIM)2.7 times and Composite Peak Signal-to-Noise Ratio (CPSNR) 11.68dB when the noise variance is 30. Meanwhile, the proposed algorithm is more efficient in noise removal and edge reservation for all the noise images with different noise variance, and that the visual quality of the denoised images is improved.Keywords：Image denoising;Double-density dual-tree complex wavelet transform;Bivariate shrinkage function;MSSIM;CPSNR- 70
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Published：2020-08-13 -
Parallel VLSI architecture of discrete wavelet transform for JPEG2000
Abstract：In order to solve the problem that the VLSI architecture of discrete wavelet transform wastes a huge amount of hardware resources, we propose a parallel VLSI architecture of discrete wavelet transform for JPEG2000. The architecture introduces (9,7) wavelet parallel filtering technique based on the time difference, so that the row processor and the column processor can process the signals in parallel way. The 2×2 transforming module makes it true that several registers substitute a lot of medium transforming memory. Experimental results show that the proposed architecture, under the tight critical path, can efficiently decrease the hardware complexity and achieve hardware utilization nearly 100%. Finally, the architecture has been implemented in post-route VHDL, and can be used as a compact and independent IP core for VDR radar image acquisition card.Keywords：JPEG2000;DWT;VLSI- 38
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Published：2020-08-13 -
Visual Inspection of Labyrinth Disc Surface Crack in an Aeroengine Based on Industrial Videoscope
Abstract：Visual inspection with endoscope plays an important role in modern fault diagnosing of aeronautic engine. An inspection approach of aperture’s surface crack on an aeroengine labyrinth disc is studied based on industrial videoscope. The appearance reason of the crack and its characteristic are analyzed firstly. An automatic recognition method of surface crack is proposed based on a localization-recognition model. A novel fuzzy fast Hough transform is presented and used to detect the circular contour to locate the aperture. Then, an interesting region is defined around the aperture, in which the image is binarized by a threshold and the binary image is thinned by a morphological method. Moreover, the chain codes in the image are analyzed to recognize the crack. The results of circular contour detection by the proposed fuzzy fast Hough Transform are compared with the results by Standard Hough Transform and Randomized Hough Transform respectively. The results show that the fuzzy fast Hough transform can detect the contour quickly and accurately. The test of crack detection is carried out in 80 aperture images, and the results indicate that the detecting accuracy is 91.2%.Keywords：visual inspection;industrial videoscope;aperture of Labyrinth disc;fuzzy fast Hough transform;crack recognition- 36
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Published：2020-08-13 -
A feature point locating algorithm for chessboard pattern based on structural characteristic of symmetry and antisymmetry
Abstract：The chessboard pattern is very useful in camera calibration and image distortion correction. Usually, these points of intersection of every four adjoining square panes are considered as feature points. The locating precision of these points will decide the precision of calibration. However, in the real photos, the point of intersection will diffuse into a group of pixels instead of one pixel. This makes the detection with high precision very difficult. In this paper, the shortcoming of present algorithms is analyzed and a kind of new detecting algorithm is proposed. This algorithm considers the structural characteristic of chessboard pattern that the pixels are central symmetrical about the points of intersection and antisymmetric about the lines of intersection of every two adjoining square panes. The precise coordinate of feature point is decided by calculating the symmetry index and antisymmetry index for every pixel. The experiment shows this algorithm is robust to noise, projective and distortion with high precision. It is also convenient for automatic detection.- 75
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Published：2020-08-13 -
Sum-modified-Laplacian-based Multifocus Image Fusion Method in Cycle Spinning Sharp Frequency Localized Contourlet Transform Domain
Abstract：Sum-modified-Laplacian-based multifocus image fusion algorithm in cycle spinning sharp frequency localized contourlet transform (SFLCT) domain is proposed in this paper. SFLCT successfully reduces significant amount of aliasing components of the original contourlet which are located far away from the desired support. However, downsamplers and upsamplers presented in directional filter banks of SFLCT make it not shift-invariant and easily cause pseudo-Gibbs phenomena around singularities. Thus, we apply cycle spinning to compensate for the lack of translation invariance property. Furthermore, typical measurements for multifocus image fusion in spatial domain are introduced into contourlet domain and Sum-modified-Laplacian (SML), evidenced in this paper with the best capability to distinguish coefficients is from the clear parts or blurry parts of images, is employed in SFCLT subbands as measurement to compose coefficients of fused images. Experimental results demonstrate the proposed fusion method outperforms block-based spatial SML method, typical cycle spinning wavelet and shift-invariant wavelet methods, and typical cycle spinning contourlet methods in term of visual appearance and objective criteria for multifocus images.Keywords：image fusion;contourlet;pseudo-Gibbs phenomena;wavelet;image processing- 60
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Published：2020-08-13
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