Chinese Version Light学术出版中心
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Issue 5 ， 2002
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Novel speckle reduction for medical ultrasound images based on edge preservation
Abstract：A novel speckle reduction for medical ultrasound images is presented based on the study of wavelet domain threshold-denoising and threshold-choosing. First, the logarithmic transform of the original image is decomposed into the multiscale wavelet domain. Then, semi-soft thresholding is used to reduce speckle noise. Finally, the denoised image is achieved by the invert DWT and the exponient transform of the estimated wavelet coefficients. Current state-of-the-art soft and hard thresholding methods based on universal threshold have been applied in actual ultrasound medical images. Compared with our method, the achieved performance improvement is quantified. Performance of the proposed method has been tested on Ultrasound images. The results show the method effectively reduces the speckle while preserving the edges of the original image.Keywords：speckle noise;semi-soft thresholding;wavelet decomposition- 69
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Published：2020-08-12 -
Optical synthesis aperture interference image technology
Abstract：Closure phase technology, U-V coverage technology and image reconstruction technology are three key technologies for optical synthesis aperture image. This paper details the closure phase theory, U-V coverage technology (which contains real time cover and non real time cover through aperture rotation) and the common method for image reconstruction, as well as the hybrid method for optical synthesis aperture image. The applications of optical synthesis aperture interference image technology are discussed in the end.Keywords：optical interference;optical synthesis aperture;image reconstruction;closure phase;U-V coverage- 53
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Published：2020-08-12 -
Method of estimating image motion based on the optical flow model
Abstract：It is one of the important technologies in electronic stabilizing images to estimate the sequence of image motion. A camera mounted on a moving vehicle collects a sequence of images. We consider a vehicle’s motion to be non-smooth when impulsion or high-frequency changes occur, the non-smooth motion will perturb the sequence of images obtained by the camera. The goal of electronic stabilizing images is to estimate the motion quantities, and correct the sequence of images, so that they are approximately the same as the images that would have been obtained if the motion of the vehicle had been smooth. Using the optical flow model to process the image motion is a good method. This paper presents the basic theory and approach to calculating image motion by using the optical flow model. It shows how to derive the optical flow constraint equation, and how to use it to estimate motion quantities. Finally, It gives the vertical and horizontal displacement between the consecutive two frames and the map of optical flow vectors.Keywords：optical flow;image motion;iteration;convergence- 46
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Published：2020-08-12 -
Blind watermarking algorithm for high fidelity of image
Abstract：This paper proposes an improved watermarking algorithm for high fidelity of image. While the watermark is embedded in the third level subband of wavelet domain according to neighboring symbol’s mean value and odd-even adjugement rule,the watermark embedding strength of the third level subband can be increased or decreased according to frequency characteristics of the second level subband. This is a blind watermarking which can confirm the copyright without the original image. Experimental results and attack analyses show that the watermark algorithm can produce the watermarked image which has high fidelity and is robust against some image processing operations, such as JPEG lossy compression, filtering and additive noise attacks.Keywords：digital watermark;wavelet transform;neighboring symbol's mean value;odd-even adjugement rule;high fidelity- 50
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Published：2020-08-12 -
Principle and realization of data acquisition of high speed logistics images and of real time foreign material elimination
Abstract：A method that realizes high speed data acquisition and real-time processing 24-bit RGB images in Windows 2000 platform is given. Since Windows 2000 itself is not a real-time operating system, it is difficult to realize continuous grabbing and real-time processing of huge data normally. Based on direct memory access and bi-buffer or multibuffer processing skills, this method is effective, and has been applied in foreign material elimination in the tobacco sorter system successfully.- 57
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Published：2020-08-12 -
Image quality evaluating method for the aerial remote camera
Abstract：In the development of the aerial remote camera, an intelligent system based on the FIFO (First In First Out), ispLSI (in-system-programmable Large Scale Integration) and PC techniques was designed for proving and evaluating image quality and observing earth objects in aerial tests. The design consideration and working principles are described, and the hardware structure and software implementation are illustrated in this paper. The system parameters are programmable for various requirements, camera images are displayed real-time, and the image data may be recorded in the file format.Keywords：remote camera;image evaluating system;CCD;FIFO;ispLSI- 47
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Published：2020-08-12 -
Realization of mass storage by using SDRAM in a high speed data acquistion and storage system
Abstract：As mass storage body, SDRAM has extensive usable value in high data processing. The architecture of the memory bank, interface signals and operation procedure are explicated, the hardware interface built by FPGA in a practical system is illustrated. The article also carefully analyzes the state transfer course when SDRAM is operated.Keywords：RAM;SDRAM;state machines;mass storage- 53
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Published：2020-08-12 -
Research on the design of a fully automatic gold wire bonder with CAD/CAE
Abstract：Fully automatic gold wire bonder is the key device of the package equipment for micro-electrons, which is associated with integrating technologies of fine mechanics, automatic control, image recognition, computer application, optics and ultrasonic wave bond. By controling three-dimensional motion of the X-Y table and bond head, precision positioning and desired line-type gold wires can be realized, and an ultrasonic wave bonded method is used. The technology route is to use integrating technologies of optics and mechatronics as well as CAD/CAE to develop new products. Ultrasonic wave bond and precision position at high speed are key technologies. By means of CAD/CAE technology, The solid models of the X-Y table and bond head assembly were built, and based on the solid models, the mechanism simulation was done. By using finite element method(FEM), the structural analysis will be done for improving design to meet the demand of bonding precision and speed.Keywords：gold wire bonders;package equipment for micro-electron;CAD/CAE;mechatronics- 52
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Published：2020-08-12 -
Research on the mechanism of a series bending arms piezoelectric micromotor
Abstract：Series bending arms are composed of two piezoelectric bimorphs, one end of which is fixed and the other end is free. Driven by two signals of the biased bar with phase difference of π/2 , the free end of a cantilever arm will move along an elliptic orbit . When the cantilever is used to drive a cylinder rotator, the end of the surface contacts the free end of the cantilever, the rotator will rotate .This paper analyzes the drive mechanism and puts forward a new drive theory.A new micormotor model was designed,and its movement parameters were tested, the rotational speed being up to 110rpm, and the torque reaching about 22.5 μNm.Keywords：series piezoelectric bimorph;Piezoelectric micromotor;mechanism- 58
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Published：2020-08-12 -
Sampling theorem to periodic non-continuous signal from cavitation of piezoelectric pump
Abstract：A general means of data processing is a sampling method, in which continuous analog data are measured non-continuously at certain time intervals as digital data, and the median value is ignored. The sampling time intervals are determined by the sampling theorem. Since both valve and no-valve piezoelectric pumps are pumps driven in a vibration form, they send a periodic non-continuous signal to cavitation. The sampling theorem is not applicable to a non-continuous signal. For this reason, the authors developed a method to apply the cavitation in a pump driven in the piezoelectric vibration form as a periodic non- continuous signal. And a sampling system using this method was manufactured.Keywords：piezoelectric pumps;data processing;sampling systems- 55
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Published：2020-08-12 -
Preparation of a self-focusing lens for optical communication
Abstract：The base glass for a self-focusing lens was prepared. The test on its optical transmittance was conducted, and analysis of the refractive index profile of a gradient index (GRIN) rod made of the base glass was performed. The results show the current base glass possesses transmittance higher than 89% in visible and near infrared bands, and the refractive index profile in the GRIN rod is in close proximity to the ideal distribution.Keywords：optical communication;gradient index;self-focusing lens;ion-exchanging- 75
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Published：2020-08-12 -
Optical code division multiple access technology and its applications
Abstract：This paper gives the background of the opitical code division multiple access(OCDMA) technology, compares its techniques with each other and sets forth the advantages. OCDMA features that it is asynchronous in time and frequency field, and does not need signal synchronization; it uses the same one central wave, and does not need wave-controlling; it has soft capacity and good security; it also can use optical fiber bandwidth sufficiently. The key techniques are depicted in detail on the basis of the fundament of optical code division multiple access. Finally,its applications are examined. DCDMA can realize real-time operation and free access when used in multi-media communications. Its protocol of media access is simple, overcoming "electron bottle-neck effect", therefore data-transmitting rate can reach the order of Tb/s when used in high-speed computer local area networks. In communication network, it is another option for multiplexing. In optical fiber access network, it can overcome conventional synchronization problem. When used in HFC network, it can also solve up-link bandwidth problem and release dual-direction communication. In CATV and VOD service, it can realize changing and dual-direction service. Therefore, the technique of optical code division multiple access can find wide applications in the future.Keywords：code division multiple access;optical fiber communication;wave division multiplex- 32
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Published：2020-08-12 -
Analysis of the parameters influencing the distance of free-space laser communication
Abstract：Free-space laser communication is becoming attractive as a new wideband wireless access technology in recent years by virtue of its many advantages, such as high-bandwidth, low cost and being license-free. Laser beam can only travel a few kilometers through the atmosphere because of some limiting factors. Based on the mathematical model of free-space laser communication, this article analyses the effects of beam divergence, atmospheric attenuation, laser power and detector sensitivity on the link range. The results show that it is effective to extend the range by narrower beam divergence and higher detector sensitivity, and higher laser power is unadvisable. The analyses in this paper are helpful for system design.Keywords：free-space laser communication;link range;optical loss- 37
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Published：2020-08-12 -
Identification of relative vibration in ultra-precision turning
Abstract：In diamond ultra-precision turning, there is unavoidably, a relative vibration between the tool and the workpiece, which influences the quality of workpiece surface. This paper simulates the influence of relative vibration between the tool and the workpiece, and theoretically analyzes the profile of radial section, circumferential section and spiral section along tool motion. The results show that different section possesses different characteristics. On the basis of analytical results, the article identifies the relative vibration between the tool and the workpiece through the data of three-dimensional topography obtained from the simulating model.Keywords：simulation;microscopic topography;diamond turning;surface analysis- 64
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Published：2020-08-12 -
Drive mechanism of the experiment tableused for camera's outdoor imaging test
Abstract：Experiment table is one of the necessary devices for camera imaging outdoors,Its moving precision and stability affect image quality directly.To satisfy the needs of camera’s imaging,the function and the structure layout of the table are introduced briefly.Then on the basis of evaluating four kinds of drive manners,a worm-driven and friction-wheel-driven mechanism is chosen, and the structure of the transfering system is presented. Finally, the driving errors of the mechanism are analyzed.Keywords：drive mechanism;friction wheel;ilder pulley assembly;stability- 65
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Published：2020-08-12 -
Design of a 3-D internal structure microscope
Abstract：Reconstruction from series slice images has become an important method to observe the 3D internal structure of biological samples. Based on the study of microtome structure and 3D reconstruction technology, several methods on designing a 3-D internal structure microscope are proposed, and such problems as sample fixing, slicing, slice image acquiring and system control have been resolved. Using 2D series section images acquired by the system, the true color 3D reconstructions of the surface and any section plane have been achieved.Keywords：D reconstruction;series slice;microscope- 62
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Published：2020-08-12 -
Design of the synchrotron light measurement system for BFPC storage ring
Abstract：This paper generalizes the properties of a synchrotron light measurement system and describes the present measurement system for BEPC. A novel system is presented according to the latest specifications. The SR extraction mirror was redesigned. The profile and intensity of beam were measured by CCD camera,and the bunch length was measured by streak camera. The imaging quality of the new system was analyzed through Zemax program,the measurement resolution of beam-size and of bunch length being 20μm and 2ps,respectively.Keywords：BEPC;synchrotron light;beamline measurement;optical system- 43
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Published：2020-08-12 -
Null lens design for small aspherical surface with large NA
Abstract：Compensation null test is a very important method in testing aspherical surface with high accuracy,in which a Zygo high accuracy digital interferometer is used. The design of a null lens is the key problem for compensation null test. In this paper, the principle of compensation null test is described. In connection with the being tested small aspherical mold surface with large NA, we developed a kind of null lens system made up of four thin lenses. The first two thin lenses form a system with very small NA mainly used to produce suitable spherical aberration; the other two form a large NA system, which together with that of the front two elements meets the null testing need. The wavefront variation of testing system due to the manufacture, test, assembly and adjustment errors is analyzed in detail. We are capable of measuring the aspherical surface to the accuracy of 0.05λ, which is enough to satisfy the testing of the mold surfaces of compact disc object lenses.Keywords：compensation null test;null lenses;small aspherical surface with large NA- 42
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Published：2020-08-12 -
Thickness effects on the microstructure, ferroelectric and dielectric properties of highly (111) oriented Pb(Zr0.53 Ti0.47)O3 thin films
Abstract：Lead zirconate titanate Pb(Zr0.53 Ti0.47)O3(PZT) ferroelectric thin films with various thickness were grown on Pt(111)/Ti/SiO2/Si(100) substrates by a simple sol-gel process, without reflux or high temperature distillation to remove water. The thin films were annealed at 550～600℃ in oxygen atmosphere by rapid thermal annealing (RTA), the highly (111)-oriented PZT thin films have been obtained. The microstructure and surface morphologies of the thin films have been studied by X-ray diffraction (XRD) and the atomic force microscopy(AFM). AFM images show that the grain thickness and RMS roughness of the highly(111) oriented PZT thin films with thickness of 0.3 and 0.56μm are 0.2～0.3μm,2～3μm and 0.92nm,34nm, respectively. The remanent polarization (Pr) and coercive electric field (Ec) are 32.2μC/cm2 and 79.9kV/cm, 27.7μC/cm2 and 54.4 kV/cm; at 100kHz, the dielectric constant and dissipation factor are 539 and 0.066, 821 and 0.029, respectively.- 60
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Published：2020-08-12 -
The latest development of optical non-contact 3D profile measurement
Abstract：D profile measurement is becoming a powerful tool for obtaining the form and structure of an object. It has important significance and widespread applications in machine vision, automatic measurement, industrial inspection, quality control, etc. Because of the advantages of high resolution, non-distruction, and quick data-obtaining, etc., it is thought to have a great future. This paper introduces some new techniques of the 3D profile measurement such as the light-section method, MMD method, and emphasizes the grating projection measurement method, giving both their advantages and disadvantages, as well as the current hot points and future directions of the last one.Keywords：non-contact measurement;profile measurement;3D- 74
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Published：2020-08-12 -
Non-contact 3-D position measurement system
Abstract：To load a missile on the emissive vehicle automatically, the positional relationship between the emissive vehicle and loading vehicle must be acquired. A non-contact 3-D position measurement system is introduced in the article. The system is composed of a planar array CCD detector and real time image processing and quick data calculating system, which can survey the positional relationship between the 3-lamp objects on the emissive vehicle and the measuring system on the loading vehicle. The principle of the measurement is discussed, and the parameter calculating equation is derived. The experiments show that the measuring precision meets the requirements by the user.Keywords：planar array CCD;non-contact measurement;position measuring system- 42
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Published：2020-08-12
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