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Issue 1 ， 2007
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Analysis on blaze characteristics of grazing incidence metal grating in soft X-ray region by differential theory with correct Fourier expansion
Abstract：In order to improve the convergence rate,a correct Fourier expand method was introduced to differential theory of the finite conductivity diffraction grating. Using modified differential theory of the finite conductivity diffraction grating, the diffraction characteristics of metal grating under grazing incidence in soft X-ray region were analysed numerically. After researching on effect of the efficiencies of the triangular, sinusoidal and rectangular gold lamellar gratings on the parameters of grating structure and incidence in soft X-ray region and -1 diffractive order, a acceptable grating technical specification was given out. Experimental result shows that for the grazing incidence gold grating in 1 200 groove/mm in soft X-ray region at blaze wavelength 10.33 nm, triangular grating efficiency can reach more than 50% when incidence is 81°, tilt angle is 2°, and apex angle is 120°. Meanwhile, some new conclusions in favor of designs on metal grating under grazing incidence in soft X-ray region were obtained.Keywords：Soft X-ray;grazing incidence grating;blaze characteristic;correct Fourier expansion;differential theory- 44
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Published：2020-08-12 -
Precise location for optical fiber surface with sampling restraint Hough transformation
Abstract：In order to improve the direction stability of light beam from optical fiber, a novel location method for optical fiber surface was proposed. The energy distribution at optical fiber surface was analyzed and Hough transformation with sampling restraint was proposed in this method to eliminate noise and obtain the contour points according to the contour character. The points divided into two classes(primitive class and noise class) were respectively transformed into parameter space to reduce memory and restrain noise to obtain the contour points. The points were set different weight for their different effect on the center of the contour in fitting process. The experimental results show that the uncertainty is less than 0.2 pixel(less than 0.4 μm) when the proposed method is used to locate optical fiber surface and a ten-fold image lens is used.Keywords：location for optical fiber surface;noise distribution between modes;Sampling Restraint Hough Transformation (SRHT);fitting with different weight- 41
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Published：2020-08-12 -
Sampling system of optical fiber Fourier transform spectrometer
Abstract：A novel design applying to sample system of optical Fiber Fourier Transform Spectrometer (FFTS) was proposed. Two quadrature signals, one of which comes from laser interference with Hilbert transform of another with correction after phase inversing, were generated. Using phase relation of two square waves, the initial position and the direction of OPD scanning were determined. These parameters was used to decide the portion of up-scanning of interference and test beam to abtain the uniform interval interferogram with similar Brault algorithm. A compact and simple sample system would be designed by DSP for further practice. The designing method not only can be applied to the FFTS, but also can be generalized to conventional Fourier transform spectrometer.Keywords：sampling system;Fiber Fourier Transform Spectrometer(FFTS);laser interference- 53
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Published：2020-08-12 -
10 Gbit/s fiber-optic transmission system using a LiNbO3 external modulator
Abstract：A structure of 10 Gbit/s fiber-optic transmission system was established to achieve 10 G optical signal transmission without relay and bit error. This system consists of NRZ format, GaInAsP multiple-quantum-well DFB lasers and LiNbO3 electro-optic modulator.The transmission experiment was carried out to abtain the parameters of the system. The effect on transmission quality were also analyzed and some key questions were studied. Experimental results show that the transmission distance without relay is about 84 km. Using CWDM technology for multiplex signal, the sensitivity of receiver is about -26.76 dBm at BER= 10-12, and the power penalty is about 0.49 dB without BER floor in the system. In the experiment, the relationship between extinction ratio and optical receiver sensitivity was also investigated, and the system runs continuously for 24 hours without error.Keywords：optical communication;extinction ratio;eye-diagram;optical receiver sensitivity- 52
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Published：2020-08-12 -
An improved way for fabricating micro-waveguide by femtosecond laser
Abstract：An improved way for fabricating micro-waveguide was presented by analysing the asymmetry of laser intensity distribution in perpendicular fabrication. By incorporating a lens into the system, the improvement of laser intensity distribution was confirmed in experiments. Experimental results show that the ratio of the diameters of the two direction of waveguide's port is more than 10:1 before improvement; the ratio is very close to 1:1 after using the improved method. Comparing with other improvement, this method is superior in simple optical path and no additional energy loss.Keywords：femtosecond laser;perpendicular fabrication;waveguide- 52
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Published：2020-08-12 -
Theoretical model for return signal of laser altimeter
Abstract：A method for calculating return waveform was deduced by the theory of Fresnel diffraction, and the models of return waveform from ground of slope, ladder and vegetation terrains were estibalished. According to the data of Geoscience Laser Altimeter System(GLAS), the waveforms of correspond return signal were obtained through computing. The relations between the waveforms of return signal and parameters of three terrains, point angle were analyzed. The conclusions show that the return waveform of slope terrain is approximately Gaussian, whose peak value and pulse width are related with slope angle and beam scanning angle; The return waveform of ladder terrain is approximately model of multi-Gaussian, whose peak value is related with ladder distribution in the footprint and simultaneity, the difference between their centers of gravity is concerned with ladder height and scanning angle; The return waveform of vegetation terrains appears multi-Gausssian, whose peak value is not only related with vegetation position, but also its area. These results provide theoretical foundation for inversion of landform and analysis of resource distribution of the earth’s surface.Keywords：laser altimeter;Fresnel diffraction;terrain model;return signal;RMS pulse width- 57
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Published：2020-08-12 -
Study on error of non-line-of-sight light propagation by single-scattering model
Abstract：The Non-Line-of-Sight (NLOS) light propagation model based on Monte Carlo (MC) method was described. Comparing with the pulse response function simulated by MC method, the error of NLOS light propagation based single-scattering approximating model was analyzed. The results show that the influence of the scattering coefficient ks and NLOS light propagation path S on the error is larger than that of absorption coefficient ka; when P (ks×S) is greater than 3, as the multiple-scattering effect is in the primary place,the error is greater than 80%; the error decreases with the decreasing P when P is littler than 3, especially, the error is below 10% when P is litter than 0.3, and then single-scattering model is suitable for studying NLOS light propagation in scattering atmosphere.Keywords：atmosphere optics;single-scattering;Monte Carlo method;Non-Line-of-Sight(NLOS) light propagation- 56
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Published：2020-08-12 -
Simulating first order stray light of FY-2 VISSR using templates
Abstract：By simplifying the framework of FY-2 VISSR, it was found that the influenceon the transform of first order stray light templates was the rotation of folding mirror edge. Based on the structural parameter of this instrument, those frameworks related to the stray light were discretely sampled, then those sampled points were projected to a plane to be observed by sensors, so the templates of the first order stray light at any angle of the folding mirror in this instrument were established. The continuity of those templates was examined. The forming of first order stray light was simulated with Gaussian point source, crescent-like edge and full disk of earth by convolution with the template, those outputs show the results are relatively close to the phenomenon of real images, and further quantitative suppressing of stray light will be on the way.Keywords：scanning radiometer;FY-2;stray light;Simulation;Template- 73
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Published：2020-08-12 -
Rearrangeable nonblocking 8×8 optical matrix switch with extended BANYAN network
Abstract：Based on the construction of the CROSSBAR network(CN) and the BANYAN network(BN), a new rearrangeable nonblocking construction called extended BANYAN network (EBN) was proposed. Taking the 8×8 optical matrix switch for example, two types of EBN construction and their rearrangeable nonblocking characteristics were studied, and the drive logic of switching units was provided. A SiO2 waveguide 8×8 optical matrix switch was designed and fabricated according to the calculated insertion loss of 3.3 dB for 8×8 optical matrix swith. The SiO2 waveguide propagation loss of 0.1 dB/cm and fiber-waveguide coupling loss of 0.5 dB/point were measured out. With the fabricated 8×8 optical matrix switch, optical insertion loss of 4.6 dB, average cross-talk of -38 dB, average polarization dependent loss of 0.4 dB, averaged switching power of 1.6 W, and response time of 1 ms were achieved. The experiment results are concident with theoretical calculation well.Keywords：optical matrix switch;extended BANYAN network;rearrangeable nonblocking;integrated optics;silica waveguide- 60
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Published：2020-08-12 -
Digital speckle correlation method of multi-scale wavelet noise reduction
Abstract：A novel Digital Speckle Correlation Method (DSCM) based on multi-scale wavelet noise reduction is proposed. Speckle patterns with Gaussian white noise or Salt & pepper noise or Poisson noise are decomposed using symlets wavelet family and processed by different noise reduction strategies. Compared with the traditional DSCM, the accuracy of this new method is improved dramatically and the relative error is less than 1%. Meanwhile, the calculated consuming time is decreased to half of the traditional DSCM.Keywords：speckle correlation;wavelet transform;multi-scale;image processing- 43
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Published：2020-08-12 -
High-gain PID controller for nanometer positioning
Abstract：Nanometer positioning was realized in a DC-motor and ball-screw-driven stage by a high gain controller. With effecting of friction on microdynamic characteristics and steadystate errors of the stage,it is a major obstacle to the achievement of nanometer positioning. In this paper,a high gain PID control structure was designed with proportional and derivative terms placed in the feedback path. Controller parameters were calculated by multiple closed-loop poles placement according to the macrodynamics alone and no friction modeling and compensation were necessary. Experimental and simulated results indicate that the PID controller can provide a sufficiently high loop gain to suppress friction effect so that single-step nanometer positioning and uniform responses of micro-motion and macro-motion are achieved. In point-to-point positioning for step heights from 10 nm to 10 mm, the positioning error is within ±2 nm.Keywords：ball screw;PID controller;nanometer positioning;friction- 36
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Published：2020-08-12 -
Study on uniformity of micro-electroformed device
Abstract：A theoretical investigation was presented to explain the effect of pulse-reverse current on the uniformity in micro-electroforming, and the micro-electroforming experiments of two different pulse-reverse currents with gaps were carried out .The two pulse-reverse currents were pulse-reverse current with gaps and pulse-reverse current without gaps in negative current, respectively. The micro-device in the experiments was the mold of micro-fluidic chip with feature width of 90 μm. All experiments consisted of three steps: making of SU-8 resist mold, micro-electroforming and removing of SU-8 resist. With the same working time and average current density, 240 min and 2.5 A/dm2, comparison was carried out between the pulse-reverse current experiments and the pulse current experiment. In contrast with the data of pulse-current micro-electroforming, better uniformity was obtained in experiments using the pulse-reverse currents. Because concentration difference over the micro pattern was improved during off-time of the negative current, surface quality was better in the experiment using the pulse-reverse current with gaps. Therefore, the results are consistent with the theoretical investigation.Keywords：uniformity;Fick second law;pulse-reverse current- 47
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Published：2020-08-12 -
Signal reception method of capacitive Lamb wave device
Abstract：A Capactive Interdigital Transducer(CIDT) was used in capacitive Lamb wave device to solve the problem that the processes of function layers in most Lamb wave devices were incompatible with classical IC process. In the devices, CIDT were used as both excitation cell and reception cell of Lamb wave, as it was possible to realize the miniaturization. Because of CIDT’s exciting and receiving the anti-symmetrical modes of Lamb wave directly, the problem of energy-coupling efficiency of transducers was solved. Basing on the analysis of several capacitance detecting circuits, the direct current circuit method was selected to meet the special demands of the device. In order to validate the application feasibility of direct current circuit method, a vibration-detecting experiment was designed. Experimental results show that the error between measurement vibration signal and its theory value is only 2.4%.Keywords：capacitive Lamb wave device;CIDT;IC process compatibility;capacitive reception;direct current circuit method- 54
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Published：2020-08-12 -
Measurement of human figure size based on laser 3D scanning
Abstract：A measuring approach for figure size from 3D human point cloud is presented. Using a light-stripe 3D laser scanning system to scan the desired pose of body, human’s three-dimensional coordinates are obtained without loss. Based on the directions of eyesight and the natural separating of two legs, the human’s orientation is adjusted to facing z positive direction. Applying manual method and maximal connectivity domain method to delete noisy points, 6 figure points and 20 figure planes are labeled on human silhouette. Two different section planes’ y coordinates are used to obtain one length size of human and a method, called convex hull method, to measure body section’s girth, respectively. Using this technique, the 34 key figure lengths and girth sizes can be measured, and the factors affecting measurement precision can be analyzed. Measurement results show that the typical measurement error of this method is lower than 3% and can meet the requirement of industry.Keywords：human figure size;measurement;convex hull method;3D point cloud;laser 3D scanning- 54
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Published：2020-08-12 -
One-dimension optical fiber array with silicon V-grooves
Abstract：one-dimension optical fiber array has been extensively applied in optical communication, optical imaging and detection systems recently. The manufacturing method of one-dimension optical fiber array and the principle of etching Si-V-grooves are introduced. The size of Si-V-grooves and the space between them are calculated according to the radius of the fiber, and a formula on the minimum depth of the Si-V-grooves is given, which related with the fiber radius and the opening space of the grooves. As a typical example, the silicon V-groove array is micromachined with anisotropic etching process,then the fibers are arranged and adhered in corresponding to the Si-V-grooves. The roughness of polished fiber surface measured with atomic force microscope (AFM) is in nanometer magnitude,and the position error is 3~5 micron,which shows these works will lay the foundation for further study on two-dimension fiber array.Keywords：optical fiber array;silicon V-groove;anisotropic etching;measurements of the fiber surface- 64
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Published：2020-08-12 -
Fiber sensor used in detecting radial vibration of high rotating speed shaft
Abstract：Optical fiber measuring technique is adopted to detect radial vibration of a high speed rotating shaft in aerial impeller pump and the principle of the detecting system is introduced in detail in this paper. A new type fiber gauge head has been developed, and relevanted compensatory approach is given. Also, the displacement characteristic modulating function is educed and the emulator curve is provided through studying of the system. Experimental results show that the system can eliminate the infection from light intensity fluctuation, fiber flexural loss and surface reflection index and detect the radial vibration of high speed rotating shaft in aerial impeller pump under the surrounding of strong electromagnetic interference and high temperature. Experiments also show that amplitude of radial vibration increases monotonously with rotation speed of the shaft ranging from 1 000 r/min to 10 000 r/min, it agrees with the physical situation.Keywords：optical fiber sensing;vibration detection;compensating;high rotating speed shaft- 51
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Published：2020-08-12 -
Circulatory system for MR fluid based on gray forecast control algorithm
Abstract：A Magnetorheological(MR) fluid circulatory system for MR finishing developed by us is introduced in this paper. The viscosity of MR fluid in non-magnetic field is obtained by measuring the pressure loss in a certain pipe. Because the viscosity control system is a big delay timing system, the gray forecast controlling algorithm is adopted to realize the viscosity control. The problem of keeping the composition of magnetorheological fluid stable can be solved. The experiment results prove that the circulatory system can keep the removal model steady.Keywords：MR finishing;MR fluid;circulatory system;keeping stable component of MR fluid;gray forecast control algorithm- 41
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Published：2020-08-12 -
Novel stereo matching algorithm based on pair-wise DNA alignment algorithm in bioinformatics and its implementation
Abstract：A novel stereo matching algorithm based on pair-wise DNA alignment algorithm is presented. The essential of both stereo matching and pair-wise DNA alignment in bioinformatics is that the correspondence points are searched by matching criteria, so the pair-wise DNA alignment algorithm is introduced to design a new stereo matching algorithm. Firstly, the principle of the dynamic programming and implementation of the proposed algorithm are presented. Then, this algorithm is significantly improved to reduce the calculation drastically, because there is a maximum possible disparity whose value can be derived from the field of view of the cameras, the physical distance between the two cameras, and the focal length of the cameras. The flow of the algorithm is designed in detail with VC6.0. Finally, the disparity maps of several different test images by means of this algorithm are shown,the advantages are low computer complexity and parallel processing. The results show that the proposed algorithm is useful and effective.Keywords：stereo matching;stereo vision;DNA sequence;pair-wise alignment algorithm;correspondence points- 35
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Published：2020-08-12 -
Object detection algorithm based on background motion compensation and hypothesis test
Abstract：According to the fact that background and object have different motion features, an object detection algorithm was proposed based on background motion compersation and hypothesis test. Motion vector was detected by a feature point corresponding algorithm and affine motion parameters were calculated through least square method. Difference image after compensation was detected by hypothesis test. After a series of morphological process, we obtained the intact moving object. Experimental results indicate that this algorithm can eliminate background motion effectivelly because of moving cameras and segment object under complex environment. The peak signal noise ratio has been improved 14.71 dB compared with two difference images.Keywords：object detection;motion compensation;hypothesis test;least square method- 59
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Published：2020-08-12 -
Application of 3D image recovering technology based on radial basic function network to engraving
Abstract：The purpose of the 3D image recovery technique is that the height of a surface is recovered by shape from shading on single image to generate the curve face of 3D object. This article puts forwards a new method of 3D image recovering based on the Radial Basis Function(RBF) network model. The curve face formula has been constructed, in which the partial derivates of output to two inputs satisfy to the equation of reflection function and the gray value is known. According to the inhibit condition between reflection function and the gray value, adjusting power factor formula and the center and width of the radial basis function to satisfy the equation of reflection function for every point of the curve face constructed, the whole curve face is recovered. This method does not need smooth control and integral control, and can get a continuous solution. The experimental results of different methods on synthesizing for example ball and vase show that the precision of max error by this method is enhanced 1~4 times, and the precision of average error by this method is enhanced 5~12 times, and the recovered curve face has consecution and smoothness. It can also recover the height of each network point in the picture, automatically interpolate any network point. It is shown that this method is suitable for the curved face of the picture for any reflection model, easy to post handle and make tool path from curve face recovered and to be engraved.Keywords：image recovery;Radial Basis Function(RBF) network;computer vision;engraving- 36
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Published：2020-08-12 -
Dimensional inspecting system of thin sheet parts based on machine vision
Abstract：According to the dimensional inspection,taking the thin sheet part of Head Gimbal Assembly (HGA) of the computer hard disk as an object, a line type industrial camera is used to acquire the image of the inspected part by line scanning. The calibration algorithm is proposed based on the property of the line scanning, and a contour vectorization algorithm is developed. The dimensional parameters of inspecting part are gained adopting the contour vectorization algorithm in which the image has been processed by filtering, calibration, binarization, edge detection and thinning. The parametric errors are obtained to evaluate the quality of a thin sheet part comparing the dimensional parameters obtained from scanned image to the dimensional parameters obtained from reading the design DXF file. The experimental results indicate that the precision of contour vectorization can reach to 1 pixel, the inspection accuracy can reach to 1 μm, the average inspection time of every part is 1 s and the inspecting system is feasible.Keywords：machine vision;thin sheet parts;dimensional inspection;line scanning;contour vectorization- 51
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Published：2020-08-12 -
Digital watermarking of encrypted in-line holography
Abstract：A new encrypted in-line holographic watermarking technique is proposed based on double-random phase encoding method,holography and digital watermarking. The proposed method includes two processes of encryption and decryption. In the encryption process, a digital watermark image is modulated by double-random phase encoding, and its in-line hologram is superposed on a content image. The watermark is recovered by means of holographic reconstruction and calculations in reverse order of encryption process without the information of the content image (blind detection). Analysis and computer simulation prove that the encrypted holographic watermark is valid, robust and secure. The watermark can be recovered from the watermarked images distorted by noise added, JPEG compression, part occluded and low pass filter. The conditions for superposing the hologram onto the content images are also investigated in detailKeywords：information optics;encryption;holography;digital watermark- 55
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Published：2020-08-12 -
Processing method of IR image based on mathematical morphology and wavelet transform
Abstract：In the purpose of recognizing and tracking targets from infrared thermal images, an infrared image processing algorithm based on mathematical morphology and wavelet transform was presented. A original image was smoothed with the open and close filters of mathematical morphology, then the infrared image was segmented with improved watershed, simultaneously, the segmented image was processed with the wavelet threshold with picture texture information. For the problem of over-segmentation regions, an effective region merging method was settled to fuse the segmentation region using the region gray median. The experiment results and algorithm performance evaluation show that the method performs well in infrared target recognition and has a good practicability.Keywords：watershed algorithm;wavelet threshold filter;infrared target detection;infrared image processing- 71
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Published：2020-08-12 -
Non-rigid medical image registration based on improved Demons algorithm
Abstract：Non-rigid registration is one of the important research issues in medical image processing field. An intensity-based automatic deformable image registration algorithm, known as the "Demons" algorithm, only depends on the image intensity gradients of the reference image to drive the floating image transform, it easily results in wrong registration when gradients are small, even being zeros. Moreover, this algorithm is not fit for the registration of multi-modality images. So, an improved "Demons" algorithm is proposed in this paper. The method adds additional external force based on the fact that the two images can make the mutual information between them maximal, and the force is defined as the gradient of mutual information between the two images with respect to the deformation field. Moreover, to avoid local extrema and speed up the registration process, the algorithm is performed in a multi-resolution manner. Experiments are conducted with both mono-modality and multi-modality images, the results show that this improved method can get a accurate registration transformation quickly.Keywords：medical image;non-rigid registration;image registration;multi-modality image;mutual information gradient- 32
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Published：2020-08-12
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