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Issue 6 ， 2008
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Experimental study on subaperture stitching interferometry of flat mirrors
Abstract：For the purpose of validate a new stitching algorithm —Sub-Aperture Stitching and Localization algorithm(SASL algorithm),this paper describes a measuring and figuring experiment of the SiC flat mirror whose shape is elliptical (225mm long in major axis, 161mm long in minor axis). First, a comparative experiment of sub-aperture stitching test with full-aperture interferometry on a 100mm diameter flat mirror is presented, in order to determine the parameter of the algorithm the precision requirement of the stitching equipment. This is followed by a successful sub-aperture stitching process for the SiC flat mirror, which contains 5 iterations of Ion Beam Figuring (IBF) process and the ultimate testing. In this process, sub-aperture stitching test offers the surface error data precisely to IBF, which ensures the quick convergence of the process to achieve a final surface error of 50nm RMS. The experiment shows that SASL algorithm relaxes the precision requirement of the stitching equipment and reduces the influence of stitching process to the result.Keywords：flat mirror measurement;sub-aperture;stitching algorithm;SiC flat mirror- 45
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Published：2020-08-12 -
Double Detectors Near infrared instrument for food component analysis
Abstract：Objetive: A double detectors near infrared (NIR) diffuse spectrometer is introduced in order to improve the stability of the spectral signal. Method :The characteristic of the spectrometer is that the monochromatic beam is separated into two beams light by a splitter. One detector collects the radiation of one beam light directly. Another beam light irradiates the sample’s surface after pass through an integrating sphere. The diffuse light of sample is collected by another detector on the integrating sphere. The value of the two detectors is compared and the absorbency is computed. Result:The instrument is used to detect the diffuse reflectivity of standard diffuse reflectance surface. The mean correlation coefficient is 0.995 between the measure diffuse reflectance and the real values. The mean standard deviation is 0.01. In addition the instrument is used to measure some components of milk powder, milk and soy sauce. The correlation coefficients of calibration are over 0.8. Conclusion: It account for that the homemade spectrometer can get the right diffuse reflectivity. And food component analysis can be done with the instrument.Keywords：Spectrometer;diffuse Near Infrared spectrum;double detectors configuration;standard diffuse reflectance surface- 67
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Published：2020-08-12 -
Study on Design Method of Planar Waveguide Concave Diffraction Gratings
Abstract：A design method for planar waveguide concave diffraction gratings is presented in the paper, which is named Modified Recursive Definition of Facet Positions. The method is based on a modification of Recursive Definition of Facet Positions. We can design the planar waveguide concave diffraction gratings accurately by using this method, especially for some special grating structures. The central position of grating facets can be presented by two constraint functions, and its numerical solution is derived from a recursive formula approach. To improve the accuracy of computation, a Newton iteration procedure is introduced in the recursive approach while computing each facet position. Two typical design examples, a flat-filed mount and a flat-top mount, are given to assess the necessity of adopting Newton iteration procedure subsequently. The simulative results prove the modification is crucial for the accurate definition of grating facet position.Keywords：Planar waveguide concave diffraction gratings;integrated optical devices;Newton iteration- 33
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Published：2020-08-12 -
The realization of Fourier telescope technology in laboratory
Abstract：Fourier telescope is an imaging technique in which the Fourier spectrum of an object is built up by sweeping fringe patterns of varying spatial frequency and orientation over the object. The modulated scattered radiation that results is collected by a non-imaging detector. We have performed a laboratory demonstration of Fourier telescope in order to confirm the validity of the fundamental measurement concept and the image reconstruction method. We show experimentally obtained images and compare them to simulated images. On-going experiments will characterize the consequences of less-than-ideal measurement conditions. Our ultimate application is the imaging of geosynchronous satellites.Keywords：Fourier telescope;active imaging;atmospheric compensation;image synthesis- 43
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Published：2020-08-12 -
Study on multi-sensors joint detection in space-based pointing
Abstract：Accurate pointing on space object is the base of many spaceflight missions. It is hard for a single detector to obtain high acquisition probability of high speed object in various space backgrounds. A method is brought forward that forecasts the motion track by using land-based radar, and then makes the space-base detector possible work in a high degree of confidence, with the aiming of infrared, laser and visible detection. It is guaranteed to obtain high acquisition probability by using information fusion. Considering the devices available and basic demand of space payload, this paper analyses the relation between detect range and probability, and obtains its joint detection probability in various backgrounds, which provides a solution for space-based pointing.Keywords：space-based pointing;multi-sensors;joint detection;acquisition probability- 40
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Published：2020-08-12 -
Temperature trajectory control based preheating method for stabilization of Zeeman He-Ne laser
Abstract：In order to stabilize the Zeeman laser accurately within a short period of time at different ambient temperatures, a temperature trajectory control based preheating method is proposed by planning the tube temperature trajectory as a modified exponential function of preheating time and tracing the planned trajectory precisely with the predictive functional control arithmetic. And experiments are made to prove the effectiveness of the proposed method. Experimental results indicate that, the Zeeman laser using the proposed method can be preheated effectively at an ambient temperature in the range of 15-25°C, so that the laser frequency can be locked in 16 minutes with a temperature-dependent frequency drift kept below 0.25MHz.Keywords：temperature trajectory control;preheating;frequency stabilization;Zeeman laser- 38
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Published：2020-08-12 -
Research on characteristic of output signal based extrinsic fiber Fabry-Perot acoustic sensors
Abstract：Extrinsic fiber Fabry-Perot acoustic sensors consisted of quartz diaphragm and end of pigtail were performed on acoustic measurement under water. The characteristic of amplitude-frequency and sensitivity of the sensors were argued in the paper. Because quadrature-point of the Fabry-Perot sensors affected the system output, the characteristics of output signals were analyzed in different conditions. The Fabry-Perot sensors were subjected hardly to fluctuation of source power and their resonant frequency were higher than other sensors. So this kind of sensors was one of choices on acoustic measurement under water well.Keywords：extrinsic fiber Fabry-Perot acoustic sensors;acoustic measurement under water;the characteristic of output signal;frequency characteristics- 52
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Published：2020-08-12 -
Analysis of thermal effect in solid state lasers with Heat capacity mode
Abstract：according to the diode pumped light intensity distribution and property of YAG materials that varies with temperature, stimulated and analyzed the change process of temperature in laser crystal media with heat capacity mode using finite element method. In order to achieve this, a side-pumping geometry with a triangle uniform distribution was adopted and its thermal conduction model of laser crystal was established. Furthermore, the different thermal effect was discussed contrastively under condition of heat capacity, continuous pumping and pulsed pumping operations. Results show that this work is useful to the experiment of the heat capacity lasers.Keywords：Solid state laser;Heat capacity mode;thermal effect;Finite element analysis- 22
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Published：2020-08-12 -
Optical Thin-film Depositing Monitoring with Four-light Beams
Abstract：Accurate thin-film thickness (TFT) monitoring is key technique of optical coating. Considering of the poor monitoring conditions of universal coating equipments with low stability, precision and automation level, a new photoelectricity-control-analysis system is developed. Based on double-frequency modulation, a photoelectric test system with four-light beams was put forward. Dual-lock-phase circuit system and comprehensive digital processing system with compound filter were used to process monitoring signals, and all automation-monitoring functions were achieved with control-analysis system. Experimental results show that standard deviation of TFT, which indicates duplication of TFT monitoring, is equal to or less than 0.55%, that signal-noise ratio approaches 1000. A very good linearity of numeral display is obtained and the display resolution limit on reflectivity is 0.02%. The linearity of static drift is very high, the drift ratio is less than 1.95%/h, and the static stabilities of the new system are double superior to the universal system. In short, the static and dynamic stabilities, the signal-noise ratio, and the control precision of TFT are extremely increased.- 41
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Published：2020-08-12 -
Study on a new-type reaction-formed joint technology in reaction bonded silicon carbide ceramics
Abstract：Joining the reaction bonded silicon carbide(RB-SiC) by a new-type reaction-formed joint technology which developed from the traditional reaction-formed joint process. Testing the thickness, microstructure, mechanical and thermal properties of the welding line. The test results show that the welding line’s thickness is very thin, during 54-77μm, and its microstructure is similar to the RB-SiC ceramic, so its mechanical property is excellent, the average bending strength of 10 joints is 307MPa. And the welding line didn’t influence the surface figure before and after the temperature of the joining blank changed fast from -10℃ to 65℃ three times.Keywords：reaction bonded;silicon carbide ceramic;reaction-formed joint technology- 36
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Published：2020-08-12 -
Analysis on Characteristics of Optical Fiber Sensor for Atmospheric Pressure
Abstract：Duo-membrane box was used as sensing component for atmospheric pressure. A micrometric displacement sensor with optical fiber was employed to inspect deformation of membrane box with air pressure changing, in order to avoid the defects in inspecting deformation, or improve and optimize performances of the sensors. A two-path optical fiber sensor was utilized to increase sensitivity and measure little changing in air pressure. The relation between optical fiber sensor output changes and atmospheric pressure changes was standardized with a standard air pressure gauge. A setup for measuring atmospheric pressure was formed. The experimental results indicate that measurement range is 900-1200hpa, resolution is 0.2hpa, and accuracy is ±0.1hPa. The measurement area position on air pressure may be changed via the changing of beginning of distance between optical detector and reflection face. Optimization of optical fiber detector parameters is necessaries to spread measurement range on atmospheric pressure.Keywords：optical fiber sensor;atmospheric pressure;Two-path measurement;sensitivity- 40
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Published：2020-08-12 -
Application of Virtual Assembly to Designing a Six-Wafer Combustor for a Silicon Micro Gas Turbine Engine
Abstract：Based on the prototype used in the MIT micro-gas turbine engine, an idea of creating its three-dimensional micro-combustor with virtual assembly technology was proposed after analyzing the traditional approaches of gemetric modeling in the field of CFD. In detail, the theory and the process of virtual assembly technologies were firstly depicted, and then the three-dimensional micro-combustor was constructed successfully in SolidWorks to demonstrate the idea. The results show creating micro-combustor based on the virtual assembly technology is prior to the traditional modeling approach , which could both decrease the cost of the products in Power MEMS and promote their industrialization.- 40
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Published：2020-08-12 -
Influence of Structure Design and Control for Movement Precision of Millimeters-scale Omni-directional Mobile Microrobot
Abstract：Movement precision is a crucial parameter for a micromanipulation of microrobot. An omni-directional mobile microrobot for microassembly in a microfactory is presented. The microrobot size is less than one cubic centimeter and is driven by four electromagnetic micromotors with 3 mm diameter. As two important aspects for the microrobot precision, the structure design and control are analyzed. The structure analysis includes the transmission system and the wheels fabrication. The virtues and drawbacks of the microrobot structure for the movement precision are also analyzed. For eliminating the influences of the drawbacks of the microrobot structure, some novel control methods and ideas which include the path planning and micromotors control are introduced. In the path planning control, the whole workspace is divided into four areas in which the moving distances of the microrobot are different. This path planning method is designed to solve the non-linear problem of the microrobot during translational movement. According the structure constrains of the electromagnetic micromotor, the vector synthesis control of the torque is devised and the torque self-balance characteristic is utilized to improve the microrobot precision. Presently, the microrobot can be achieve 0.07mm/step during translation, and 0.83°/setp during steering, which is three times compared with common control method. The microrobot can do simple microassembly micromanipulation supervised by a computer vision system. The microassembly experiment result demonstrates the validity of these microrobot control methods and concepts based on the actual characteristics of the microrobot structure.Keywords：mobile microrobot;microassembly;micromotor;Precision- 37
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Published：2020-08-12 -
Modeling and Process Analysis of the Mastering for Multi-level Run-length-limited Optical Discs
Abstract：Abstract: Objective: For conventional optical discs, the pit width and depth remain the same. But for multi-level run-length-limited optical discs, both the pit width and depth vary with the levels. Thus stricter requirement for mastering process is needed. The mastering process is worthy of in-deep research. Method: A photolithography model for optical disc mastering is built, where the vector diffraction is used to calculate the intensity distribution of the focused light spot, and the light propagation in multi-layer film structure is used to describe the light propagation in photo-resist. Result: The experiment and simulation results are present, including the influences of key process parameters on typical multi-level pit width and depth. These process parameters include photo-resist thickness, development time and developer concentration. The decrease of photo-resist thickness will cause increased width and deceased depth. The effects of the increases of development time and developer concentration are similar, each of which will cause increased width and depth. Conclusion: The accordance of experiment and simulation validates the model. Analysis results are helpful to the practical multi-level disc mastering. Meanwhile , the model can be used to analysis other process parameters, and mastering of other disc format mastering.Keywords：Optical storage;Multi-level;Mastering process;Photolithography model- 29
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Published：2020-08-12 -
Fluid pressure and its effects on hydrodynamic suspension ultra-smooth machining
Abstract：A hydrodynamic suspension machining system based on NC machine tool is constructed. And a compliant machining apparatus was developed. Fluid pressure distribution in the machining clearance was analyzed by hydrodynamics. The experiments to find influence on fluid pressure of machining clearance and motor rotate speed. Meanwhile, by conducting experiments, the correlation between the surface roughness of machining clearance and motor rotate speed was revealed. Experimental results indicate that with the increasing of motor rotate speed and decreasing of machining clearance, fluid pressure increased gradually and then decrease relatively after it reached certain value. When the motor rotate speed is 6000 r/min, the hydrodynamic pressure obtained max value. It was shown that when the machining clearance is between 5 and 40 µm, the machining effect is distinct. And in the condition of maintaining clearance 10 µm and hydrodynamic pressure maintained to be 5N, the machining effect is optimal.Keywords：ultra-smooth machining;hydrodynamic suspension;fluid pressure;machining effect- 27
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Published：2020-08-12 -
Study on MEMS Laminated Microstructure Sulfur Dioxide Poison Gas Sensor
Abstract：Aimed at the technical difficulty of low electric conductivity of new-style organic semiconductor, bring forward a kind of laminated microstructure on porous upper electrode, use the technology of vacuum deposition to form gas sensitive film, and adopt MEMS micro-fabrication to make gas sensor. According as the equivalent circuit and the technology boundary condition, through the conductance formula deduce that the output conductance of the sensor has increased 1000 times, has settled the signal gathering problem of organic semiconductor. Through SEM microcosmic pattern, affirm the best condition, evaporating electric current is 100~120A, and evaporating time is 8~12s. The surface of gas sensitive film is covered with activated granules, which are inosculated in the secondary chemical reaction, like rice grain, about 200nm, symmetrical, uniform and has order holes. The testing result indicates that CuPcxPANI1-x doped with vitriol whose coefficient of proportionality is 0.15~0.35 has the best sensitivity to SO2, considering reducing the interference of H2S, select CuPc0.35PANI0.65; when heating voltage VH is 1~2.5V, sensitivity and responsive restorability will be enhanced, and responsive time is 30 seconds; the output characteristic of sensor is single logarithmic linear relation, and the detecting range is 0~200×10-6; through examination of stability for six months, output impedance is less than or equal to ±5%, sensitivity is less than or equal to 10%.Keywords：MEMS microstructure;gas sensor;sulfur dioxide poison gas detection- 49
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Published：2020-08-12 -
Study of a Vertical Drive ultrasonic Feeder
Abstract：Baced on the principle of piezoelectric drive , A new conception ultrasonic vibration feeder is developed and a new ultrasonic transducer for it is designed. the transducer is tested. Its parameters such as resonance frequency and impedance are obtained by impedance analyzer. The transducer’s amplitude is surveyed and we also get the relational curve between oscillation amplitude and frequency. The vibration thoery of the ultrasonic vibration feeder is studied, It’s structure parameter is calculated, correlative equation is built. And then the performance of the ultrasonic feeder is measured. Results show that the proposed ultrasonic feeder can carry or feed Small solid object.Keywords：piezoelectric drive;ultrasonic;Feeding device- 47
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Published：2020-08-12 -
Sensors Network Design for Flexible Surface Shape Measurement
Abstract：It is very difficult to measure and monitor the shape of solar array as well as the flexible surface. The sensor array has been configured using fiber bragg grating (FBG) sensors which built a sensor network with the technology of spatial-division-multiplexing (SDM) and wavelength-division-multiplexing (WDM) in the paper. The number of sensors was determined according to the wave transmitting theory and the demodulation scope of the device. The distribution for those sensors that are embedded is based on the strain of the solar array. The sensor distributed at the top of the surface shape. The sensor is dense if the strain is great but in reverse is sparse. Based on the finite element analysis of the surface, the sensors network of the surface that emulated the solar array was implemented. Furthermore, the precision of the sensors array system has been calibrated. The experiment shows that there was a linear relationship for FBG sensors. The distribution of the sensors was in reason and the sensor network could measure many shapes of the solar array. The error of sensors measurement is only 0.4 percent and the errors of the flexible surface measurement is four percent if the length of FBG packaging is less than forty millimeter.Keywords：FBG;sensor network;surface inspect;Embedded sensor- 55
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Published：2020-08-12 -
Surface topography signal separation with double density wavelet transform
Abstract：With the characteristic of its time-frequency analysis, wavelet can overcome the defect of the traditional filtering methods and appropriately evaluate the surface topography. This paper proposed a novel signal separation method based on double density wavelet transform (DDWT) for engineering surface analysis. The method provides near shift-invariance in surface texture extraction and improves the separation accuracy of roughness, waviness and other frequency component.Keywords：wavelet analysis;surface topography;double density wavelet;surface evaluation- 30
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Published：2020-08-12 -
Image Retrieval Based on Combining Local and Global Features
Abstract：A novel image retrieval algorithm combining global statistical feature and local bitmap feature was proposed. Firstly, compute the mean value and the stand deviation of every image, capturing the global statistical feature. Then divided every image into 4×4 image blocks without overlapping, and compute the mean value of every image block according to block truncation code, if the mean value is larger than the one of the whole image, then the image block is set as “1”, otherwise, the image block is set as “0”,so capturing the image bitmap features. Finally, do retrieval by integrating the features normalized to get the best similar matching function. Experiment result indicates that: the retrieval performance of integrating two global and local features is more prior than using single feature; Comparing with other similar schemes, the algorithm is robust, and retrieval efficiency is higher.Keywords：image retrieval;statistical featur;block truncation code;image block- 37
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Published：2020-08-12 -
Target Precise Positioning Method Based on CCD Video Amplitude Controller
Abstract：A new algorithm to conduct target precise locating is designed, mainly including dual fixed thresholds edge detection and subpixel edge locating by gray weighted centroid algorithm. By means of quantitative numerical adjusting to the 2 parts of the loop, integration time and program controlled gain(PGA), a linear CCD video amplitude controller feedback system is devised so that each frame can keep a constant peak gray value of the target image to satisfy the needs of dual thresholds edge detection, and this light adjusting loop system features a less difficult light path design and lower cost. Compared with traditional binarization method, it is a simpler system with a more excellent algorithm, and its engineering application shows that this system, with a subdivided degree of less than 1/10 pixel, can function spot target locating precisely. The system scheme of the 2-varible stepless light adjusting numerical controller possesses an important reference value to the future design of multiple-varible light adjusting video system.Keywords：dual fixed thresholds;edge detection;Subpixel;light adjusting system- 47
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Published：2020-08-12 -
Two-stage Uncertainty Evaluation of Stereo Reconstruction
Abstract：This paper deals with the problem of evaluating the uncertainties associated with nonlinear camera model based stereo reconstruction using the law of propagation of uncertainty. The procedure of stereo reconstruction involves two consecutive stages: calibrating camera models and reconstructing a 3D point from its image projections. The output quantities of the first stage, the parameters of camera models, constitute a part of the input quantities of the second stage. The analytical expressions for uncertainty propagation during reconstructing a 3D point are proposed. At last, the results of an experiment with synthetic data are validated using Monte Carlo Simulation, and some typical application examples are presented.- 35
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Published：2020-08-12 -
A Fast Stereo Matching Algorithm Based on Adaptive Window and Graph cuts
Abstract：According to the disadvantage of the large computation of the stereo matching algorithm based on graph cuts, a new stereo matching algorithm is presented. First, adaptive window is obtained in virtue of image edge features. Second, the SSD matching method as a similarity decision criterion is introduced to determine the initial disparity map, and then left-right conformity verification is adopted to remove mistake matching points. The initial disparity is used as a reference for the function when the energy function is structured. Finally the optimization of disparity distribution is obtained to achieve the minimum global energy by graph cuts algorithm. Experimental results based on standard stereo image rig are compared with other methods and demonstrate that not only the proposed algorithm has better performance of processing the large low texture areas and the occluded pixels, but also running time is short and two-thirds faster than the original algorithm. It can satisfy the demands of engineering practices completely.Keywords：stereo matching;Adaptive window;disparity map;Graph cuts;Energy function- 26
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Published：2020-08-12 -
Point in Polygon Testing based on Normal Direction
Abstract：Two vectors compose of point and edge of polygon was defined, the normal direction of these two vectors was calculated, the normal direction is the reference for testing. A line was drawn through the point, there are some crossing points between line and some edges of polygon, the normal direction of point and these edges was calculated, if the number of positive normal and negative normal is same, the point is outside the polygon, otherwise the point is inside the polygon. This method didn’t make mistake like half-line method, and it is sample than other methods. The computation is decreased. It is proved be an effective and simple robust algorithm by programming, and it is suitable for most case self-intersection polygon.Keywords：Computer Application;Point in Polygon Testing;Polygon;Normal Direction- 50
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Published：2020-08-12 -
The Application of multi-functional digital watermarking in copyright protection
Abstract：In this paper, a kind of multi-functional digital watermarking is provided, which can be applied to the copyright protection and user tracking of still images. The algorithm of the former, which implemented copyright protection, was based on the characteristic of systematic code in RS error correcting code. Aimed at client and Certificate Authority, this algorithm designed two different extracting methods, which ensured two different requirements of robustness. The algorithm of the latter, which implemented user tracking was based on SVD quantization and grouping inserting watermark. It reached the standard of strong robustness and could achieve 100% extracting with certain attracting. Experiment results the validity of this algorithm.Keywords：Multi-functional digital watermarking;Copyright protection;singular value decomposition;RS error correcting code- 35
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Published：2020-08-12 -
A Scale And Direction Adaptive Mean Shift Tracking Algorithm
Abstract：Classic Mean shift based tracking algorithm uses fixed kernel-bandwidth, which limits the performance when the object scale exceeds the size of the tracking window. Although some modified algorithms can settle the problem of object zooming in a way, these algorithms are helpless to the object rotation. Based on the analysis of the scale-space theory and the current Mean shift algorithms, a scale and direction adaptive mean shift tracking algorithm is proposed. Experimental results show that the new method can effectively and accurately obtain the best description of the target areas for the first frame, and the new mean shift tracking algorithm can adapt to any kind of object’s movements.Keywords：Mean shift;target tracking;scale space;ellipse regularization log operator- 28
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Published：2020-08-12 -
Design of driving circuit for frame transfer area CCD area CCD
Abstract：A kind of circuit used in driving large area CCD of high frame frequency was designed, and it used frame transfer area CCD FT18 as sensor. This kind of high speed driving circuit can increase the angle of visual field with the constant condition of video in trail, and solve the requirement of the big visual field of searching goal. First, the structure and the specification of area CCD FT18 sensor are introduced in this paper, then the circuits of working clock and power driver for the sensor are proposed. The noises of the video signal (KTC noise and 1/f noise) are filtered by using the correlated double sampling (CDS) technique, and the signal-to-noise ratio of the system is also enhanced. Radiation scale has been done after design. According to the scale experiment data, it is linear to be able to find out CCD to respond degree, have verified drive circuit work normal. Entire system adopts the Field Programmable Gate Array ( FPGA ) as key controller, and hardware is designed by the software which is based on the modularization design method from top to bottom. The development efficiency has been enhanced.Keywords：moving target tracking;frame transfer area CCD;driving clock;CDS;FPGA- 53
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Published：2020-08-12 -
Research on Hyperspetral Image Compression Based on 3D SPIHT Algorithm
Abstract：As 3D image, the data size of hyperspectral image is too large for storage or transmission, so it is necessary to compress hyperspectral image efficiently. In this paper, 3D SPIHT is applied to hyperspectral image compression. Firstly, band grouping is performed to obtain the processing unit, and then the three dimensional wavelet transform is applied to each group to eliminate both spatial and spectral redundancy. Finally, 3D SPIHT algorithm is used to encode the wavelet coefficients. Both integer and float wavelet are used for lossless and lossy compression respectively. Experimental results show that the proposed algorithm has better lossy coding performance, while lower lossless coding performance than predictive coding technique.Keywords：hyperspectral image;three-dimensional wavelet transform;3D SPIHT algorithm- 38
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Published：2020-08-12
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