The theoretical simulation on electrostatic distribution of 1st proximity region in proximity focusing low-light-level image intensifier
Author(s):
Liandong Zhang;
Xiaofeng Bai;
De Song;
Shencheng Fu;
Ye Li;
Qingduo Duanmu
Show Abstract
Low-light-level night vision technology is magnifying low light level signal large enough to be seen by naked eye, which uses the photons - photoelectron as information carrier. Until the micro-channel plate was invented, it has been possibility for the realization of high performance and miniaturization of low-light-level night vision device. The device is double-proximity focusing low-light-level image intensifier which places a micro-channel plate close to photocathode and phosphor screen. The advantages of proximity focusing low-light-level night vision are small size, light weight, small power consumption, no distortion, fast response speed, wide dynamic range and so on. It is placed parallel to each other for Micro-channel plate (both sides of it with metal electrode), the photocathode and the phosphor screen are placed parallel to each other. The voltage is applied between photocathode and the input of micro-channel plate when image intensifier works. The emission electron excited by photo on the photocathode move towards to micro-channel plate under the electric field in 1st proximity focusing region, and then it is multiplied through the micro-channel. The movement locus of emission electrons can be calculated and simulated when the distributions of electrostatic field equipotential lines are determined in the 1st proximity focusing region. Furthermore the resolution of image tube can be determined. However the distributions of electrostatic fields and equipotential lines are complex due to a lot of micro-channel existing in the micro channel plate. This paper simulates electrostatic distribution of 1st proximity region in double-proximity focusing low-light-level image intensifier with the finite element simulation analysis software Ansoft maxwell 3D. The electrostatic field distributions of 1st proximity region are compared when the micro-channel plates’ pore size, spacing and inclination angle ranged. We believe that the electron beam movement trajectory in 1st proximity region will be better simulated when the electronic electrostatic fields are simulated.
Research on the inversion of one-dimensional attitude of the space shuttle model based on scattering spectroscopy
Author(s):
Yu Liu;
Jing Shi;
Ya Fan;
Wei Song;
Xin-hui Miao;
Min-shan Zhang;
Rong Xu;
Yong Tan;
Hong-xing Cai
Show Abstract
The detection and recognition for the attitude of space target is a technical problem and research focus. In this paper the attitude inversion technique of space target was explored based scattering spectroscopy. The scattering spectra of the space shuttle model instead of space target in the laboratory were detected in 0~360° direction at 10° intervals, and the spectral database of the one-dimensional rotating space shuttle model was established. Based on spectral bidirectional reflectance distribution function (SBRDF) theoretical model, the experimental data were compared with the data in the database using residual as a reference. When the rotation angle of the space shuttle model was 8°, 68°, 293°, the angle corresponding to the minimum residual was 10°, 70°, 290°. The results indicated that the inversion of rotation angle of the space shuttle model was achieved and inversion accuracy is better than 5°. According to the redundancy of spectral data (700 effective bands), if the angle interval of spectral data was reduced, the attitude inversion of space target of higher angle accuracy can be achieved. In this paper, for the first time the one-dimensional attitude inversion of the space shuttle model was realized based on the scattering spectrum, and the correlation between scattering spectra and attitude was confirmed. This research is helpful to the application of spectroscopy in the field of the attitude inversion of space target.
The analysis on the optical power of focal length tunable liquid lens
Author(s):
Chenguang Zhang;
Yiquan Liu;
Jianguo Xin
Show Abstract
The optical aperture of the liquid lens has a effect on the optical power, but until now, there is no research report on this effect .In this paper, based on Laplace function, the effect of the optical aperture on the optical parameters of the liquid lens has been analyzed, it is found that the optical aperture plays an important role on the optical power dynamic tuning range.
Low spherical aberration of the focal length tunable liquid lens
Author(s):
YiQuan Liu;
ChenGuang Zhang;
JianGuo Xin
Show Abstract
For the liquid lens based on electro-wetting, the optical aperture influences the profile of the liquid drop due to the capillary effect, therefore, it will has an effect on the aberration of liquid lens. The spherical aberration caused by the different optical apertures with the different slope has been investigated by ray tracing. The analysis results have shown that the absolute value of positive and negative spherical aberration at the aperture of 4mm goes down by 2μm when the optical aperture goes up from 4.2mm to 5mm and that gradient of positive spherical aberration decrease with increasing optical aperture, that gradient of negative spherical aberration increase with increasing optical aperture. The critical turning voltage when spherical aberration changes from positive to negative is independent of optical aperture.
Performance simulation of heterodyne synchronous receiving system in coherent optical communication
Author(s):
BaiChao Zheng;
ShouFeng Tong
Show Abstract
Coherent optical communication technology is currently a hotpot research of communication. Coherent optical communication heterodyne synchronous receiving system is researched. The basic principle of coherent optical communication is introduced in briefly, the heterodyne synchronous receiving system is established in the basis of the principle. A simulation model, charactered as Synchronous receiving system of Coherent Heterodyne, was rightly set up. In addition, with regarding actual device parameters as reference, and under the situation of 2.5Gbps communication rate and 10km as communication distance, Optisystem was operating to accomplish simulation analysis for capacity of this system in different signal-radiation rate and distinguish weather condition. The consequence of simulation demonstrated: as the receiving sensitivity is relatively high when compared communication system of coherent heterodyne to that of IM/DD, the coherent optical communication system has lower requirement to signal rate of radiated laser in the same condition. Consequently, it can be concluded that coherent heterodyne system has high receiving sensitivity, and strong capacity of resisting disturbance, moreover it is appropriately communicated in channel with relatively high disturbance, it possesses great advantages to IM/DD method in atmosphere channel which has strong disturbance.
Human motion recognition based on features and models selected HMM
Author(s):
Haixiang Lu;
Hongjun Zhou
Show Abstract
This paper research on the motion recognition based on HMM with Kinect. Kinect provides skeletal data consist of 3D body joints with its lower price and convenience. In this work, several methods are used to determine the optimal subset of features among Cartesian coordinates, distance to hip center, velocity, angle and angular velocity, in order to improve the recognition rate. K-means is used for vector quantization and HMM is used as recognition method. HMM is an effective signal processing method which contains time calibration, provides a learning mechanism and recognition ability. Cluster numbers of K-means, structure and state numbers of HMM are optimized as well. The proposed methods are applied to the MSR Action3D dataset. Results show that the proposed methods obtain better recognition accuracy than the state of the art methods.
In-line print defect inspection system based on parallelized algorithms
Author(s):
Chao Lv;
Hongjun Zhou
Show Abstract
The core algorithm of an on-line print defects detection system is template matching. In this paper, we introduce a kind of edge-based template matching based on Canny’s edge detection method to find the edge information and do the matching work. Of all the detection algorithms, the most difficult problem is execution time, in order to reduce the execution time and improve the efficiency of execution, we introduce four different ways to solve and compare. They are Pyramidal algorithm, Multicore and Multi-Threading algorithm based on OpenMP, a Parallel algorithm based on Intel AVX Instruction Set, GPU computing based on OpenCL model. Through the results, we can find different characters of different ways, and then choose the best for your own system.
Simulation and detection of electron back-scattering in ion barrier films of micro-channel plate
Author(s):
Shencheng Fu;
Ye Li;
Feng Shi;
Zhuang Miao;
Hongchang Cheng;
Qingduo Duanmu
Show Abstract
The simulation calculation and analysis on the electron backscattering for ion barrier films (IBFs) of Al2O3 were performed by Monte Carlo methods. Simulation and experimental detection both found that electron backscattering ratio is inversely proportional to the incident electron energy, proportional to the film thickness and density. But if the film is thick enough, the back scattering ratio will not continue to increase, will maintain a relatively stable value. This work provided a theory support for fabricating high performance low-level-light device.
Photochromism of spirooxazine-doped polymers studied by monitoring dynamics of holographic gratings
Author(s):
Xin Xie;
Meiling Zheng;
Shencheng Fu;
Feng Shi;
Xiuli Wang;
Naiyan Zhan
Show Abstract
As an organic photochromic material, spirooxazine attracted widespread attention because of its high fatigue resistance and thermal stability. In this paper, the photochromism of spirooxazine was studied by monitoring the dynamics of holographic gratings in spirooxazine-doped polymer films. A theoretical description for the transformation of spirooxazine and merocyanine molecules was carried out, which agrees well with the experimental results. The photochromism of spirooxazine-doped different matrixes were studied, the photochromic rate and fatigue resistance of spirooxazine-doped SiO2 films were found to be better than spirooxazine-doped PMMA films.
Charge transfer efficiency improvement of 4T pixel for high speed CMOS image sensor
Author(s):
Xiangliang Jin;
Weihui Liu;
Hongjiao Yang;
Lizhen Tang;
Jia Yang
Show Abstract
The charge transfer efficiency improvement method is proposed by optimizing the electrical potential distribution along the transfer path from the PPD to the FD. In this work, we present a non-uniform doped transfer transistor channel, with the adjustments to the overlap length between the CPIA layer and the transfer gate, and the overlap length between the SEN layer and transfer gate. Theory analysis and TCAD simulation results show that the density of the residual charge reduces from 1e11 /cm3 to 1e9 /cm3, and the transfer time reduces from 500 ns to 143 ns, and the charge transfer efficiency is about 77 e-/ns. This optimizing design effectively improves the charge transfer efficiency of 4T pixel and the performance of 4T high speed CMOS image sensor.
TCAD simulations for a novel single-photon avalanche diode
Author(s):
Xiangliang Jin;
Jia Yang;
Hongjiao Yang;
Lizhen Tang;
Weihui Liu
Show Abstract
A single-photon avalanche diode (SPAD) device with P+-SEN junction, and a low concentration of N-type doping circular virtual guard-ring was presented in this paper. SEN layer of the proposed SPAD has high concentration of N-type doping, causing the SPAD low breakdown voltage (~14.26 V). What’s more, an efficient and narrow (about 2μm) guard-ring of the proposed SPAD not only can withstand considerably higher electric fields for preventing edge breakdown, but also offers a little increment in fill factor compared with existing SPADs due to its small area. In addition, some Silvaco TCAD simulations have been done and verify characteristics and performance of the design in this work.
The analysis of demodulation characteristic on the resonant optical gyro using frequency modulation technique
Author(s):
Liang Ning;
Lijun Guo;
Gang Fang;
Cihang Liu
Show Abstract
The resonator optic gyro (ROG), which utilizes a resonance frequency change due to the Sagnac effect, is a promising candidate for the next generation inertial rotation sensor. In this paper, we first analyzed the signal detection theory and made the demodulation curve modeling. Second, the ROG demodulation test system is set up using the laser frequency modulation spectroscopy technique. The resonance curve of the resonator is detected by the photodiode (PD) and then demodulated by the LIA. By testing at λ=1550nm, and the free spectral range (FSR), the full width at half maximum (FWHM), the depth and the finesse of resonance are 2191.41MHz, 65.55MHz, 0.9 and 33.43 respectively. Calculated from the demodulation signal, the dynamic range of the gyro is from +2.04×103rad/s to -2.04×103rad/s. The slope K1 of the linear part in the demodulation signal is estimated to be 0.8×10-7V/Hz. A basic agreement between experimental results and theoretical calculated values was achieved.
The law of wet oxidation rate in 850nm VCSELs
Author(s):
Yuan Feng;
Guojun Liu;
Changling Yan;
Yongqin Hao;
Yong Wang;
Peng Lu;
Yang Li;
Zaijin Li
Show Abstract
Wet-oxidation experiments in a nitrogen environment at high temperatures are conducted to improve the photoelectricity performance of the 850nm VCSELs. It is very important to accurately control the oxidation aperture.We have carried out upon the wafer of VCSELs with the same structure by changing the furnace temperature and oxidation time, then micro-probe analyses have been examined at different oxidation depth by scanning electron microscope (SEM) and by X-ray. Oxidation products are examined at different oxidation depths of oxidation layer and each component content is analyzed, we get the law of the wet-oxidation. The oxidation process thermal stability and precision can be improved by lowering the oxidation temperature and prolonging the oxidation time.
New method of echo detection for diffuse reflection laser ranging
Author(s):
Kun-peng Wang;
Yan Zhang;
Xing-qi Wang;
Lin Quan;
Peng Zhao
Show Abstract
The echo received from diffuse reflection laser ranging (DRLR) system for space debris and satellite without corner reflector is too weak to detect available echo-photon robustly. A new method based on image saliency feature for echophoton detection was proposed, which used the concept of image saliency in computer vision field to describe echophoton distribution feature. The O-C residue distribution information was used to generate O-C residue image, and then saliency feature recognition, Piecewise Hough detection and polynomial fitting were adopt orderly to obtain available echo signal. The actual experiment results show the effectiveness and robustness of the algorithm.
H∞ control for fast steering mirror based on the incremental PI controller
Author(s):
Zhiliang Yu;
Ning Cui;
Xinglin Chen;
Chuanghuan Xu;
Kairui Cao
Show Abstract
In the paper , H∞ Control for Fast Steering Mirror of precision tracking in space optical communication tracking and pointing system is studied. A H∞ performance design problem based on the Incremental PI is described. It is also suggested that the design for Fast Steering Mirror H∞ performance can be formulated as a H∞ control problem, a uncertainty β factor is described.The performance β factor to system bandwidth and disturbance attenuation are revised and optimized appropriately, the factor decides the system bandwidth.The H∞ Controllers f or Fast Steering Mirror based on Incremental PI are solved.The method of H∞ Controllers is simple, easy to adjust, small overshoot and enabling high probability and fast establishment of laser communication links in intersatellite laser communication.
Retina-like sensor image coordinates transformation and display
Author(s):
Fengmei Cao;
Nan Cao;
Tingzhu Bai;
Shengyu Song
Show Abstract
For a new kind of retina-like senor camera, the image acquisition, coordinates transformation and interpolation need to be realized. Both of the coordinates transformation and interpolation are computed in polar coordinate due to the sensor’s particular pixels distribution. The image interpolation is based on sub-pixel interpolation and its relative weights are got in polar coordinates. The hardware platform is composed of retina-like senor camera, image grabber and PC. Combined the MIL and OpenCV library, the software program is composed in VC++ on VS 2010. Experience results show that the system can realizes the real-time image acquisition, coordinate transformation and interpolation.
Optical signal measurement of iso-octane autoignition behind reflected shock wave
Author(s):
Qisheng Chen;
Zhiguo Dou;
Lan Li
Show Abstract
Ignition delay time of diluted iso-octane/Air mixtures were measured in a single pulse reflected shock tube. In this work, the onset of ignition was determined by monitoring both the pressure history and the emitted light corresponding to OH* emission. The photomultiplier tube (PMT) in specially designed housing at CaF2 window were used with 310±5nm filters to measure the ultraviolet OH* emission. Experiments were performed at temperatures between 1295K and 2487K, pressures about 1 atm. and varying equivalence ratios (Φ;=0.25, 0.5, 1.0, 2.0). Long shock tube dwell time (about 15ms) was achieved by tailored contact surface operation under such conditions. To simulate real engine environment, liquid fuel aerosol was generated by the supersonic atomizer, and the size of fuel droplet in aerosol was measured. Both pressure and OH*emission histories were obtained to determine the ignition delay time and the relative strength of the ignition process. The OH* emission time history data showed that there were different behaviors of iso-octane in ignition process under varying temperatures. Several potential chemical kinetics mechanisms were used to simulated iso-octane autoignition under the same conditions. Analysis of the experiments results and simulations supported the validation of those chemical kinetics mechanisms. The experimental data was consistent with the prediction of mechanism in low temperatures and the experiment data showed that the factors of temperature and equivalent ratio have different effect on the ignition delay time
Experimental study of polarization and backscattering noise of resonator fiber optic gyro
Author(s):
Liang Ning;
Lijun Guo;
Gang Fang;
Cihang Liu
Show Abstract
We analyzed the parameters and main noise influence on resonator fiber optic gyro’s finesse, and put forward the main way to improve the finesse. Then, we built the optical fiber ring resonator test system, inhibited the polarization fluctuation noise by using the polarization controller and polarization-laser, and at last took the backscattering noise tests. The experimental results showed that the inhibition of the polarization fluctuation noise has made the fiber optic resonant ring finesse increase from 64.67 to 84.57, resonant depth increase from 0.5033 to 0.7308. At the same time, we measured the intensity ratio of the Rayleigh backscattering light and main signal of 0.0267%. It provides a helpful reference for manufacturing of resonator fiber optic gyro.
An adaptive fusion strategy of polarization image based on NSCT
Author(s):
Chang-xia Zhao;
Jin Duan;
Chun-he Mo;
Guang-qiu Chen;
Qiang Fu
Show Abstract
An improved image fusion algorithm based on the NSCT is proposed in this paper. After decomposition NSCT method of multi-scale and multiple directions, polarization image was decomposed into two parts: low frequency sub-band and high frequency band-pass images. The fusion strategy of combining local regional energy and gradient structure similarity were used in low-frequency coefficients. While in the high-frequency band-pass coefficients part, the fusion strategy of the location spatial frequency as the correlation coefficient was used. The intensity image and polarization degree image are fused for improving the sharpness and contrast of the image. The experiments show that the algorithm is effective to improve the imaging quality in the turbid medium.
Temperature characteristic of 808nm VCSELs with large aperture
Author(s):
Yuan Feng;
Dawei Feng;
Yongqin Hao;
Yong Wang;
Changling Yan;
Peng Lu;
Yang Li
Show Abstract
In order to study the output characteristics of 808nm vertical cavity surface emitting laser(VCSEL) with large aperture at different temperature, 808nm VCSEL with 500μm emitting diameter are fabricated with Reticular Electrode Structure(RES). Lasing wavelength, optical power and the threshold current are measured by changing the temperature of heat sink. And an output power of 0.42W is achieved at 1.3A at room temperature under continuous wave operation. The central wavelength is 803.32nm, and the full width at half maximum is 0.16nm, the temperature shift is 0.06nm/℃, the thermal resistance is 0.098℃/mW. The testing results show that 808nm VCSEL with large aperture is good temperature characteristic.
The relevant research on AOD and concentration of PM2.5 pollutant
Author(s):
Huan Yao;
Xiaochang Ni;
Xuan Wang;
Tong Li;
Lijuan Xu;
Zhenming Song
Show Abstract
To study the relationship between Aerosol Optical Depth (AOD) and concentration of PM2.5(Particulate Matter) basing on CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) data, 51 samples among the CALIPSO Level 2 aerosol profile data of local region from January to April 2014 are selected. After screening these 51 samples under the decided conditions, such as system stability and the type of the materials, the AODs of the samples are calculated. Then a linear regression model is constructed through Matlab software, in which AOD is independent variable and PM2.5 is dependent variable. All the data are fit by the selected five functions: linear, logarithmic, exponential, power, and quadratic. Experimental results show that the value of correlation coefficient of the quadratic equation model is the best one among the functions. So it is feasible to monitor the concentration of PM2.5 using the AOD calculated from CALIPSO Level 2 data.
Overview and trend of steady tracking in free-space optical communication links
Author(s):
Siyuan Yu;
Zhongtian Ma;
Feng Wu;
Jing Ma;
Liying Tan
Show Abstract
The tracking is mainly used to maintain the established optical communication links (OCLs) in pointing, acquisition and tracking (PAT) ensuring the reliability of date transmission. The structure of pointing and tracking assembly, implementation methods and performances of beacon detector are reviewed. Analysis results show that reducing beam divergence and emission power, using closed-loop composite axis structure tracking system, removing acquisition beacon, analyzing far-filed characters of bidirectional tracking beam are critical to achieve high reliability of data transmission and long steady tracking in free-space optical communication.
A method for detecting small targets based on cumulative weighted value of target properties
Author(s):
Xing Jin;
Gang Sun;
Wei-hua Wang;
Fang Liu;
Zeng-ping Chen
Show Abstract
Laser detection based on the “cat’s eye effect” has become the hot research project for its initiative compared to the passivity of sound detection and infrared detection. And the target detection is one of the core technologies in this system. The paper puts forward a method for detecting small targets based on cumulative weighted value of target properties using given data. Firstly, we make a frame difference to the images, then make image processing based on Morphology Principles. Secondly, we segment images, and screen the targets; then find some interesting locations. Finally, comparing to a quantity of frames, we locate the target. We did an exam to 394 true frames, the experimental result shows that the mathod can detect small targets efficiently.
Study on the gain characteristic of dual MCP cascade system
Author(s):
Jingjing Xie;
Yiqing Zang;
Yang Li;
Ye Li
Show Abstract
The low gain of single micro-channel plate (MCP) detector system has a lot of restrictions. So the dual MCP system is widely applied in many fields. Many experiments showed the gain was proportional to initial electron energy in single MCP system. If we improve the initial energy that collide with the second MCP in dual MCP system, it may have beneficial influence on the system gain. In order to check these hypothesis, we use the “Secondary Electric Field Acceleration” cascade structure in experiments. The results show the correctness through the comparison test with conventional 'V' type cascade structure. In this paper, we describe the different between these two structure and discuss the influence factors in their system gain. It gives a reference in the cascade system that with high gain and it also takes a great significance on the weak-light-detection field.
Research on defogging technology of video image based on FPGA
Author(s):
Shuo Liu;
Yan Piao
Show Abstract
As the effect of atmospheric particles scattering, the video image captured by outdoor surveillance system has low contrast and brightness, which directly affects the application value of the system. The traditional defogging technology is mostly studied by software for the defogging algorithms of the single frame image. Moreover, the algorithms have large computation and high time complexity. Then, the defogging technology of video image based on Digital Signal Processing (DSP) has the problem of complex peripheral circuit. It can’t be realized in real-time processing, and it’s hard to debug and upgrade. In this paper, with the improved dark channel prior algorithm, we propose a kind of defogging technology of video image based on Field Programmable Gate Array (FPGA). Compared to the traditional defogging methods, the video image with high resolution can be processed in real-time. Furthermore, the function modules of the system have been designed by hardware description language. At last, the results show that the defogging system based on FPGA can process the video image with minimum resolution of 640×480 in real-time. After defogging, the brightness and contrast of video image are improved effectively. Therefore, the defogging technology proposed in the paper has a great variety of applications including aviation, forest fire prevention, national security and other important surveillance.
An iterative trilateral filter algorithm for depth map
Author(s):
Kai Gao;
Yan Piao;
Jing-he Zhang
Show Abstract
Depth map is critical in Free-viewpoint television (FTV) system, and the quality of reconstructed depth map impacts the quality of rendering view. Depth map obtained from TOF camera, not only appears with large flat area and sharp edges, but also contains lots of noises. In order to achieve the aim of decreasing the noise and keeping the accurate of edges in the depth map, an iterative trilateral filter is proposed by combining bilateral filter and the introduced factor of illumination normal in this paper. The experimental results show that the proposed method can reduce the noise obviously,and keep the edge of the depth map from TOF camera well.
Design of fire detection equipment based on ultraviolet detection technology
Author(s):
Zhenji Liu;
Jin Liu;
Sheng Chu;
Chao Ping;
Xiaobing Yuan
Show Abstract
Utilized the feature of wide bandgap semiconductor of MgZnO, researched and developed a kind of Mid-Ultraviolet-Band(MUV) ultraviolet detector which has passed the simulation experiment in the sun circumstance. Based on the ultraviolet detector, it gives out a design scheme of gun-shot detection device, which is composed of twelve ultraviolet detectors, signal amplifier, processor, annunciator , azimuth indicator and the bracket. Through Analysing the feature of solar blind, ultraviolet responsivity, fire feature of gunshots and detection distance, the feasibility of this design scheme is proved.
Influence by x-ray facula on dimension measurement
Author(s):
Xulei Qin;
Ye Li;
Qingduo Duanmu;
Peng Zhao
Show Abstract
Based on the imaging features of the original image intensifier of X-ray, the light halo caused by X-ray projective halation is analyzed, the result shows the stray X-ray energy is lower than the direct X-ray energy. The screen brightness generated by the image intensifier of X-ray stimulated by the stray X-ray energy is weaker than that generated by the direct X-ray energy. In addition the projector facula reflected from the direct X-ray is focused on the central region of X-ray image intensifier, therefore a toroidal ring similar to the solar halation is formed around the projector halation. The results of the theoretical analysis and experimental discovery show this phenomenon caused by X-ray tube on X-ray image intensifier can not be eliminated and in the system of X-ray size detection composed of them the X-ray halation will reduce the detection accuracy resulting in measurement results’ deviation dispersion under given conditions. This kind of nonlinear system error can not be canceled out by the segmented modification of coefficient compensation but it can be restrained through the adjustment of correction coefficients. After the physical testing and comparison of the physical normal size the accuracy of 0.1mm of the compensated X-ray measurement results after the adjustment of correction coefficient has been reached. The results are highly reproducible and the method of the segmented coefficient compensation has been improved.
Research and test on noise factor of two-cascaded MCPs
Author(s):
Yiqing Zang;
Jingjing Xie;
Yang Li;
Ye Li
Show Abstract
Comparing with the single micro-channel plate (MCP), the structure of cascaded micro-channel plates possesses the advantages of higher gain and lower dark current, etc. In order to improve its performance further, a structure of two-cascaded MCPs with accelerating electric field was raised. As noise characteristic is an important indicator to evaluate the performance of optoelectronic devices, therefore, it is of great significance to test the noise factor of two-cascaded MCPs. The structures of two-cascaded MCPs with and without accelerating electric field are taked as research object. Through changing their working conditions, the SNR of each situation were measured respectively. And the noise factor of each situation were deduced. The experimental results show that structure of two-cascade MCPs with the accelerating electric field possesses higher SNR and lower noise factor.
THz spectrum of iron corrosion products
Author(s):
Di-bo Wu;
Hui Zhao;
Hong-lan Liu;
Kun Zhao;
Qing Sun
Show Abstract
Fe2O3, Fe3O4 and Fe(OH)3 as three different corrosion products of iron and their mixture were investigated in the 0.2~2.0 THz using terahertz time-domain spectroscopy (THz-TDS) in vacuum environment at room temperature. Frequency and reflectivity of Fe2O3, Fe3O4, Fe(OH)3 and their mixture were calculated by fourier transform. There are no peaks in the THz range, but the reflectivities of samples have significant differences. The results demonstrate that the three different corrosion products of iron and their mixture can be analyzed distinctly according to the characteristics in THz range. THz-TDS can be used in further analysis of iron corrosion and pipeline corrosion detection.
Design and simulation of a new compound eye with a wide field of view
Author(s):
Shuming Yuan
Show Abstract
Put forward a compound eye possessing a wide field of view (FOV), which is characterized by small and compact structure. Based on the total reflection theory, the ommatidia on the edge of the compound eye are designed with free-form surface prism, which enables the light beams reflected inside the ommatidium. This contributes to ommatidia of small size and distortion decrease of the marginal ommatidia, finally image quality of the marginal FOV is dramatically enhanced and the FOV of the compound eye is broadened obviously. The size of the designed compound eye is Φ12.2mm×3mm, the FOV increases to 180º. However, the image distortion whitin the entire FOV is smaller than 25%. The MTF is still larger than 0.1 even at the frequency of 100lp/mm. The simulation of the proposed compound eye structure is conducted using the LightTools. Results indicate that there is no crosstalk between adjacent ommatidia and it can image with high quality.
Solar-blind ultraviolet optical system design for missile warning
Author(s):
Yu Chen;
Furong Huo;
Liqin Zheng
Show Abstract
Solar-blind region of Ultraviolet (UV) spectrum has very important application in military field. The spectrum range is from 240nm to 280nm, which can be applied to detect the tail flame from approaching missile. A solar-blind UV optical system is designed to detect the UV radiation, which is an energy system. iKon-L 936 from ANDOR company is selected as the UV detector, which has pixel size 13.5μm x 13.5 μm and active image area 27.6mm x 27.6 mm. CaF2 and F_silica are the chosen materials. The original structure is composed of 6 elements. To reduce the system structure and improve image quality, two aspheric surfaces and one diffractive optical element are adopted in this paper. After optimization and normalization, the designed system is composed of five elements with the maximum spot size 11.988μ m, which is less than the pixel size of the selected CCD detector. Application of aspheric surface and diffractive optical element makes each FOV have similar spot size, which shows the system almost meets the requirements of isoplanatic condition. If the focal length can be decreased, the FOV of the system can be enlarged further.
Experimental investigation of gamma ray radiation effects on 1550nm single mode fiber
Author(s):
Qingfeng Liu;
Jing Ma;
Liying Tan;
Yanping Zhou;
Chi Che;
Qingbo Yang
Show Abstract
We compared the degradation of two kinds of 1550nm single-mode optical fibers following the irradiation by gamma ray (60Co). Over a total dose of 9.06×104 rad, the absorption coefficient increased while the rates were different between samples. The influence of ionizing radiation is theoretically analyzed. In room temperature annealing experiment, the absorption coefficient of Corning sample was recovered visibly, but Alcatel sample continues to deteriorate. It is suggested that different producing technology and doping are clearly influence the generation and recombination process of color center.
Research on silicon microchannel arrays oxide insulation technology
Author(s):
Ke-xin Wu;
Qingduo Duanmu;
Guozheng Wang;
Ji-kai Yang;
Yang-qiang Kou
Show Abstract
Silicon microchannel plates (Si-MCP) is widely used in the photomultiplier, night vision, X- ray intensifier and other areas. In order to meet the requirements of high voltage electron multiplier, Si-MCP need to prepare a layer of silicon dioxide in the microchannel to improve the insulating properties. There are many methods for preparing SiO2 layer, such as thermal growth, magnetron sputtering method and chemical vapor deposition etc. The thermal oxidation method is often used for preparation of insulating layer that it grows film thickness uniformity, compact structure, simple process and so on. There will be bending deformation phenomenon of silicon microchannel arrays in high temperature oxidation process. The warpage of Si-MCP has brought great for difficulties of subsequent processing. Silicon crystals has the properties of plastic deformation at high temperature, this article take full advantage of this properties by which the already bending deformation of silicon microchannel arrays can be restored to flat.
Research on resistance properties of conductive layer materials of microchannel plate film dynode
Author(s):
Ling-ling Peng;
Qingduo Duanmu;
Ji-kai Yang;
Guo-zheng Wang
Show Abstract
Silicon Microchannel Plate(MCP)is a new image multiplier devices based semiconductor process technology. Compared with the traditional glass MCP, Silicon MCP has an advantage in technology that the dynode materials and the substrate materials are separate. At the same time, the dynode preparation process and the microchannel arrays are also separate. Two different dynode conductive layer films are prepared: polysilicon conductive films prepared by low pressure chemical vapor deposition (LPCVD) and AZO thin films coated by atomic layer deposition (ALD). The conductive films coated by ALD are superior to dynode conductive films prepared by LPCVD. By comparing the resistivity of conductive polysilicon thin film and AZO thin film of different Al concentrations doped, AZO thin film of different Al concentrations doped is a more suitable conductive layer dynode material to satisfy the MCP conductive layer resistivity requirements.
Research on the detection technology to dim and small target
Author(s):
Yu Liu;
Feng Chen;
Jianming Huang;
Xiangquan Wei
Show Abstract
With the development of Space Technology, the demand to Space Surveillance System is more urgent than before. The paper studies the dim and small target of long range. Firstly, it describes the research status of dim and small target abroad and the two detection principle of DBT and TBD. Secondly, it focuses on the higher-order correlation method, dynamic programming method and projection transformation method of TBD. Finally, it studies the image sequence simulation of different signal to noise ratio (SNR) with the real-time data from the aircraft in orbit. The image sequence is used to experimental verification. The test results show the dim and small target detection capability and applicable occasion of different methods. At the same time, it provides a new idea to the development of long-distance optical detector.
A set of measurement systems for the dynamic visible scatter characteristics of space target
Author(s):
Jianming Huang;
Xiangquan Wei;
Dongchun Yang;
Yuzhi Xiao;
Xiaoli Fan
Show Abstract
Exact and reliable dynamic visible scatter characteristics of space target, can not only be used for the design and development of visible sensor as well as the research of algorithm for target capture, recognition and tracking, but also can offer reference bases for the flow programming of space test. A set of simulation measurement system for the dynamic visible scatter characteristics of space target is introduced in this paper. The simulation problem of dynamic visible scatter characteristics of space target is solved, under the circumstance of laboratory with different azimuth angle and pitch angle of solar illumination as well as different azimuth angle and pitch angle of observation. The dynamic visible scatter characteristics of space target can be obtained directly by such system, and the test data can be used for the verification of the analyzing model for the visible scatter characteristics of space target.
Comparison of swarm intelligence algorithms in atmospheric compensation for free space optical communication
Author(s):
Zhaokun Li;
Jingtai Cao;
Wei Liu;
Jianfeng Feng;
Xiaohui Zhao
Show Abstract
We use conventional adaptive optical system to compensate atmospheric turbulence in free space optical (FSO) communication system under strong scintillation circumstances, undesired wave-front measurements based on Shark-Hartman sensor (SH). Since wavefront sensor-less adaptive optics is a feasible option, we propose several swarm intelligence algorithms to compensate the wavefront aberration from atmospheric interference in FSO and mainly discuss the algorithm principle, basic flows, and simulation result. The numerical simulation experiment and result analysis show that compared with SPGD algorithm, the proposed algorithms can effectively restrain wavefront aberration, and improve convergence rate of the algorithms and the coupling efficiency of receiver in large extent.
Optical design of athermalization stepping-zoom dual FOV MWIR system
Author(s):
Ping Du;
Cui-ling Zhao;
Yaguang Geng;
Tao Ma
Show Abstract
According to the athermalization theory a optical passive athermalization stepping-zoom dual FOV MWIR system in 3μm~5μm designed in this paper, Through the rational combination of infrared optical materials and aspheric surface realized the design of optical passive athermalization. The optical system only use five lens and the optical materials is commonly such as germanium, silicon and Znse. The focal length is 90mm/150mm, the total length is 139mm. The MTF of the two fields are ≥0.5@16lp/mm at -45°C~+60°C, which shows its optical performance approximates to the diffraction limit.
Design of natural user interface of indoor surveillance system
Author(s):
Lili Jia;
Dan Liu;
Mu-Jin Jiang;
Ning Cao
Show Abstract
Conventional optical video surveillance systems usually just record what they view, but they can’t make sense of what they are viewing. With lots of useless video information stored and transmitted, waste of memory space and increasing the bandwidth are produced every day. In order to reduce the overall cost of the system, and improve the application value of the monitoring system, we use the Kinect sensor with CMOS infrared sensor, as a supplement to the traditional video surveillance system, to establish the natural user interface system for indoor surveillance. In this paper, the architecture of the natural user interface system, complex background monitoring object separation, user behavior analysis algorithms are discussed. By the analysis of the monitoring object, instead of the command language grammar, when the monitored object need instant help, the system with the natural user interface sends help information. We introduce the method of combining the new system and traditional monitoring system. In conclusion, theoretical analysis and experimental results in this paper show that the proposed system is reasonable and efficient. It can satisfy the system requirements of non-contact, online, real time, higher precision and rapid speed to control the state of affairs at the scene.
Design of wideband multilayer planar absorber using a new differential evolution algorithm
Author(s):
Chuan Lin;
Anyong Qing;
Jiefeng Zang
Show Abstract
Design of wideband planar absorber using real electromagnetic composite materials is considered in this paper. A new differential evolution, dynamic differential evolution with best of random differential mutation, is applied to solve this problem. To simplify the problem, a suitable objective function and regulation scheme have been designed to transform the constrained multi-objective problem into unconstrained single-objective one. The effects of total thickness and investigated frequency band have been studied. Four-layer planar absorbers for different cases have been successfully designed.
Design of multipass frequency selective surface
Author(s):
Jiefeng Zang;
Chuan Lin;
Anyong Qing
Show Abstract
Equivalent circuit model of the frequency select surface is given, and a feasible method of design of multi-pass frequency selective surface is discussed. Based on the method, a novel frequency selective surface with two pass bands is presented. The simulation results indicate that, the center frequencies of the bands are at 2.95GHz and 8.6GHz, and the 3dB bandwidth is 3.5% and 5%. Also the center frequencies and the transmittance of the pass bands are affected less by the polarization direction and incident angel of the wave, or the structure exhibits a great filter feature as a frequency selective surface.
Retrieval of aerosol optical thickness over land from airborne polarized measurements in Tianjin and Tangshan
Author(s):
Han Wang;
Xiaobing Sun;
Weizhen Hou;
Cheng Chen;
Jin Hong
Show Abstract
New developed sensor was called Atmosphere Multi-angle Polarization Radiometer (AMPR). It provides airborne multi-spectral, multi-angular and polarized measurements. Based on the measurements, a method to retrieve aerosol optical thickness (AOT) was developed. To reduce the ambiguity in retrieval algorithm, the key characteristics of aerosol model over East Asia are constrained. Initial surface reflectance was estimated from measurements at 1640 nm. With iteration the surface polarized reflectance tends to the real value together with AOT. Retrieved cases were selected from measurements in Tianjin. Validation between AOTs from AMPR and CE318 is encouraging. The AOTs along the track shows reasonable temporal and spatial variation.
Research of two analysis methods on propagation modes of light in optic slab waveguide
Author(s):
Hongwei Wang;
Zhaoyang Wang;
Shifeng Xu
Show Abstract
Optic slab waveguide has the function of controlling light, transferring light and distributing light. It is the most important component in integrated optoelectronics. However, the research of theory on optic waveguide is not enough. Based on the decomposition of the light vector, two methods of the boundary conditions of electromagnetic field and the phase condition of stand wave were used in this paper. Then, the self-consistent solution of modals of the light propagation in optic waveguide was obtained.
Separation of FBG wavelength mixed caused by temperature and vibration based on improved Fast-ICA and self-adapting
Author(s):
Shanchao Jiang;
Jing Wang;
Qingmei Sui;
Qinglin Ye;
Yuqiang Cao;
Lei Jia
Show Abstract
The purpose of conventional techniques for multiplexing fiber Bragg gratings (FBGs) is that each FBG has its own wavelength or unique intensity of reflected light. The cost pf per channel is at least of a few hundred dollars. All these limit the FBG points increasing at fiber measuring system. Based on improved Fast-ICA and self-adapting, this paper focuses on the separation of two same wavelength FBGs mixing model caused by temperature and vibration. Simulation experiment is carried out based on the initial wavelengths of two FBGs are both 1550.515nm and the temperature fluctuation range is 0-0.5°C and amplitude and frequency of exterior vibration are 0.01nm and 10Hz. Simulation data show that the separation steps consume 1.3884s and mean and mean square of absolute errors between the original and separated signals are 8.11·10-9, -5.83·10-12, and 2.57·10-6, 2.42·10-9, correspondingly. Therefore, through using this separation method, two same wavelength FBGs could achieve simultaneously measurement of temperature and vibration at one channel. This could double measuring points of fiber detection system, effectively.
Influence and analysis on ion barrier film to the noise factor of micro-channel plate
Author(s):
Yu-feng Zhu;
Fan Zhang;
Ni Zhang;
Jing Nie;
Dan Li;
Tai-min Zhang;
Shu-fei Wang;
Xiao-jian Liu;
Zhao-lu Liu
Show Abstract
The noise factor, which is the main factor affecting the noise performance of image intensifier and can accurately reflect the noise characteristics of the micro-channel plate(MCP), is the ratio of the input signal to noise ratio (SNR) and the output SNR. According to definition of noise factor of micro channel plate, noise mechanism and test principle, noise factor of filmed MCP test system is established in order to study the technical way to reduce noise factor of MCP. Because the input surface of the MCP is covered with ion barrier film to block the feedback ions, which have a great impact on the noise factor of the MCP. Hence, noise factor of filmed MCP and un-filmed MCP is measured respectively, and noise factors with different materials and different filmed thickness are measured too. Relationships between noise factor and filmed thickness, noise factor and output SNR of image intensifier have been obtained. That is valuable to reduce the noise of filmed MCP.
Design of high-brightness 976nm fiber-coupled laser diodes based on ZEMAX
Author(s):
Linbao Hou;
He Zhang;
Li Xu;
Yang Li;
Yonggang Zou;
Xin Zhao;
Xiaohui Ma
Show Abstract
Fiber-coupled laser diodes have become essential sources for fiber laser pumping and direct energy applications. To obtain high power, high brightness semiconductor laser beam output, a 976nm wavelength fiber coupling module with 12 single-emitter laser diodes has been designed using ZEMAX optical design software, and single-emitter has an output power of 10 W with a 105μm wide emission aperture. The core diameter of output fiber is set as 105μm with a numerical aperture (NA) of 0.15. Finally, the simulated result indicates that the module will have an output power over 100W with the brightness of 16.63MW·cm-2·str-1, and the coupling efficiency achieved 85%.
Measurement and analysis on ion barrier film of MCP by ion beam sputtering deposition
Author(s):
Ni Zhang;
Yu-Feng Zhu;
Dan Li;
Jing Nie;
Fan Zhang;
Tai-min Zhang;
Xiao-jian Liu;
Zhao-lu Liu;
Wei Cheng;
Chang Chen
Show Abstract
Ion barrier film (IBF) on the input side surface of Micro-channel Plate (MCP ) has a dual role in the high electron transmittance and high ionic blocking rate, and the quality of the film is very strict, so to choose a good coating way to meet the application of IBF-MCP in the third image intensifier is very important. Ion beam sputtering deposition (IBSD) technology is a relatively mature coating technology which can obtain a dense strong adhesion and smooth, high-quality film. This paper is carried out from the quality analysis on surface morphology, crystal structure and coating quality and comparison with qualified film to determine a better way to prepare IBF on the input side surface of MCP.
The design and implementation of microstrip passband filter based on ADS simulation
Author(s):
Yue Han
Show Abstract
This paper introduced to the methods and design processes of the design of coupled micro strip bandpass filters with ADS, and it focused on the calculation of parameters and device simulation during the design with ADS. Two circuit boards with different dielectric constant were used and the design, optimization and simulation of filters were operated. It’s found through the comparison of simulation results that the dielectric constant of the circuit board is the key indicators that impact the size of the structure and properties of the circuit, and the feasibility and effectiveness of the optimization and the design of microstrip bandpass filters with ADS software were also proved.
Application of image processing for terahertz time domain spectroscopy imaging quantitative detection
Author(s):
Li-juan Li;
Sheng Wang;
Jiao-jiao Ren;
Ming-xing Zhou;
Duo Zhao
Show Abstract
According to nondestructive testing principle for the terahertz time domain spectroscopy Imaging, using digital image processing techniques, through Terahertz time-domain spectroscopy system collected images and two-dimensional datas and using a range of processing methods, including selecting regions of interest, contrast enhancement, edge detection, and defects being detected. In the paper, Matlab programming is been use to defect recognition of Terahertz, by figuring out the pixels to determine defects defect area and border length, roundness, diameter size. Through the experiment of the qualitative analysis and quantitative calculation of Matlab image processing, this method of detection of defects of geometric dimension of the sample to get a better result.
A low noise high readout speed 512×128 ROIC for shortwave InGaAs FPA
Author(s):
SongLei Huang;
Zhangcheng Huang;
Yu Chen;
Hengjing Tang;
Jiaxiong Fang
Show Abstract
A low noise high readout speed 512×128 readout Integrated circuit (ROIC) based on capacitance trans-impedance amplifier (CTIA) is designed in this paper. The ROIC is flip-chip bonded with Indium bumps to InGaAs detectors which cutoff wavelength is 1.7μm, as a hybrid structure (InGaAs FPA). The ROIC with 30μm pixel pitch and 50fF integrated capacitance, is fabricated in 0.5μm DPTM CMOS process. The results show that output noise is about 3.0E-4V which equivalent readout noise is 95e-, output voltage swing is better than 2.5V; the dynamic range of InGaAs FPA reaches 69.7dB@2ms, and the power dissipation is about 175mw. The peak detectivity of InGaAs FPA reaches 2E12cmHz1/2w-1 at 300K without TEC cooling.
Study on numerical simulation of flowfield in afterburner for ducted rocket
Author(s):
Xiaoyu Ding;
Xing Jin;
Peng Zhang
Show Abstract
Ducted rocket has been widely concerned on account of its high specific impulse, combustion stability and convenient maintenance which mixes the exhaust from a fuel gas generator with air from air inlet, and burns to produce thrust. It is necessary to establish two-dimensional or three-dimensional numerical models based on computational fluid dynamics to study on the flowfield in afterburner which is the key of ducted rocket because of expensive experiments, which is aimed at providing theoretical foundation for ducted rocket’s development. In this paper, the gas-phase turbulent combustion process in afterburner with dual inlet three-dimensional mode was simulated numerically by solving Favre-averaged compressible turbulent N-S equations, the renormalization group (RNG) k-ε turbulence model was applied to simulate the turbulent flow, and Eddy-Dissipation Model (EDM) was applied to simulate gas combustion. Through simulation, situation analysis of flowfield in afterburner was done, and the influence of mixing combustion on afterburner was studied by taking air inlet angles and air-fuel ratio into account respectively. The results indicate that the distribution of temperature in afterburner is nonuniform, the backflow and axial swirl produced by gas mixing have an important influence on afterburner combustion. As air inlet angle is increased, the intensity of gas mixing is enhanced which is beneficial for afterburner combustion. That increasing air-fuel ratio is able to strength contact of oxygen with fuel gas, so that more fuel gas is consumed in the same location which is more beneficial for afterburner combustion.
Comparative study on atmospheric correction methods of visible and near-infrared hyperspectral image
Author(s):
Qian He;
Jingli Wu;
Guangping Wang;
Chang Liu;
Tao Tao
Show Abstract
Currently, common atmospheric correction methods usually based on the statistical information of image itself for relative reflectance calculation, or make use of the radiative transfer model and meteorological parameters for accurate calculations. In order to compare the advantages and disadvantages of these methods, we carried out some atmospheric correction experiments based on AVIRIS Airborne Visible and Near-Infrared hyperspectral data. It proved that, the statistical method is simple and convenient, but not wide adaptability, that can only get the relative reflectance; while the radiative transfer model method is very complex and require the support of auxiliary information, but it can get the precise absolute reflectance of surface features.
Study of image matching algorithm and sub-pixel fitting algorithm in target tracking
Author(s):
Ming-dong Yang;
Jianjun Jia;
Jia Qiang;
Jian-yu Wang
Show Abstract
Image correlation matching is a tracking method that searched a region most approximate to the target template based on the correlation measure between two images. Because there is no need to segment the image, and the computation of this method is little. Image correlation matching is a basic method of target tracking. This paper mainly studies the image matching algorithm of gray scale image, which precision is at sub-pixel level. The matching algorithm used in this paper is SAD (Sum of Absolute Difference) method. This method excels in real-time systems because of its low computation complexity. The SAD method is introduced firstly and the most frequently used sub-pixel fitting algorithms are introduced at the meantime. These fitting algorithms can’t be used in real-time systems because they are too complex. However, target tracking often requires high real-time performance, we put forward a fitting algorithm named paraboloidal fitting algorithm based on the consideration above, this algorithm is simple and realized easily in real-time system. The result of this algorithm is compared with that of surface fitting algorithm through image matching simulation. By comparison, the precision difference between these two algorithms is little, it’s less than 0.01pixel. In order to research the influence of target rotation on precision of image matching, the experiment of camera rotation was carried on. The detector used in the camera is a CMOS detector. It is fixed to an arc pendulum table, take pictures when the camera rotated different angles. Choose a subarea in the original picture as the template, and search the best matching spot using image matching algorithm mentioned above. The result shows that the matching error is bigger when the target rotation angle is larger. It’s an approximate linear relation. Finally, the influence of noise on matching precision was researched. Gaussian noise and pepper and salt noise were added in the image respectively, and the image was processed by mean filter and median filter, then image matching was processed. The result show that when the noise is little, mean filter and median filter can achieve a good result. But when the noise density of salt and pepper noise is bigger than 0.4, or the variance of Gaussian noise is bigger than 0.0015, the result of image matching will be wrong.
Effect of annealing time on the adsorption of cesium atoms
Author(s):
Sen Niu;
Feng Shi;
Hongchang Cheng;
Long Wang;
Lei Yan;
Hongli Shi;
Yuan Yuan;
Chang Chen
Show Abstract
The gallium arsenide (GaAs) photocathode generally requires a high temperature thermal cleaning before (Cs, O) activation in order to obtain an atomic level clean surface. The process is useful to adsorb and deposit cesium and oxygen atoms. Generally considered, the photocathode needs to be cooled to 60℃ to activate for achieving better results. People usually keep the annealing time for at least 1.5 hours in practical production. In order to explore the effect of annealing time on cesium atoms which were adsorbed on GaAs photocathode, the experiment monitored the activation curves of three GaAs photocathodes samples which annealed for 0.5 hour, 1.0 hour, 1.5 hours respectively, and then compared the occurrence moment of the photocurrent and the first cesium peak by different annealing waiting time. The difference of the activation curves reflects indirectly that the photocathode surface temperature had an influence on the adsorption of cesium atoms during activation process. This phenomenon could explain from two aspects about atoms adsorption and electronic transport. The work has referential significance for experimental research and industrial production.
A research on the effects of practicing Baduanjin on the lower extremities by using sEMG
Author(s):
Li Jin;
Ran Li;
Jing Chen;
Ye Tian
Show Abstract
The purpose of this study was to evaluate the effects of practicing Baduanjin exercises on the lower extremities of subjects, using electromyography analysis, and values of IEMG were calculated. [Subjects] Forty, healthy adults were randomly assigned as subjects to two groups: SG (Study Group, n=20) who received twelve weeks of Baduanjin training, and CG (Control Group, n=20), who received no training. [Methods] A sixteen-channel sEMG system (ME6000, Mega Electronics Ltd., Kuopio, Finland) was selected to record and measure activity changes in two muscles (vastus medialis and vastus lateralis). [Results] After twelve-week of Baduanjin training, the results of this study showed that the SG group had significant increases in values of IEMG in second, fifth and seventh section of the Baduanjin exercises. In second section, the values of IEMG had increased for 56.95% in vastus lateralis (p < 0.05) and for 40.04% in vastus medialis (p < 0.05). In fifth section, the values of IEMG had increased for 37.61% in vastus lateralis (p < 0.05) and for 33.83% in vastus medialis (p < 0.05). In seventh section, the increasement of IEMG values was 47.19% in vastus lateralis (p < 0.05) and 49.31% in vastus medialis (p < 0.05). [Conclusion] This study indicated that performing twelve-week of Baduanjin training can significantly increase the strength and the physical function of the lower extremities among healthy adults. With no adverse events from exercise were reported during the training procedure, the safety and low intensity of Baduanjin exercise was also proved, it could be widely taken as an appropriate no-risk treatment exercise for healthy adults.
Numerical simulation of different pulse width of long pulsed laser on aluminum alloy
Author(s):
Mingxin Li;
Guangyong Jin;
Wei Zhang;
Gui-bo Chen;
Juan Bi
Show Abstract
Established a physical model to simulate the melt ejection induced by long pulsed laser on aluminum alloy and use the finite element method to simulate the whole process. This simulation is based on the interaction between single pulsed laser with different pulse width and different peak energy and aluminum alloy material. By comparing the theoretical simulation data and the actual test data, we discover that: the theoretical simulation curve is well consistent with the actual experimental curve, this two-dimensional model is with high reliability; when the temperature at the center of aluminum alloy surface increases and evaporation happens after the surface temperature at the center of aluminum alloy surface reaches boiling point and later the aluminum alloy material sustains in the status of equilibrium vaporization; the keyhole appears on the surface of the target, an increment of the keyhole, the maximum temperature at the center of aluminum alloy surface gradually moves inwardly. This research may provide the theoretical references to the understanding of the interaction between millisecond pulsed laser and many kinds of materials, as well as be beneficial to the application of the laser materials processing and military field.
Research on space-based optical surveillance's observation strategy of geostationary-orbit's pitch point region
Author(s):
Xue-ying Wang;
Wei An;
Yu-hao Wu;
Jun Li
Show Abstract
In order to surveillance the geostationary (GEO) objects, including man-made satellites and space debris, more efficiently, a space-based optical surveillance system was designed in this paper. A strategy to observe the pinch point region was selected because of the GEO objects’ dynamics features. That strategy affects the surveillance satellites orbital type and sensor pointing strategy. In order to minimize total surveillance satellites and the revisit time for GEO objects, a equation was set. More than 700 GEO objects’ TLE from NASA’s website are used for simulation. Results indicate that the revisit time of the surveillance system designed in this paper is less than 24 hours, more than 95% GEO objects can be observed by the designed system.
Numerical simulation of different pulse width of long pulsed laser on aluminum alloy
Author(s):
Mingxin Li;
Guangyong Jin;
Wei Zhang;
Guibo Chen;
Juan Bi
Show Abstract
Established a physical model to simulate the melt ejection induced by long pulsed laser on aluminum alloy and use the finite element method to simulate the whole process. This simulation is based on the interaction between single pulsed laser with different pulse width and different peak energy and aluminum alloy material. By comparing the theoretical simulation data and the actual test data, we discover that: the theoretical simulation curve is well consistent with the actual experimental curve, this two-dimensional model is with high reliability; when the temperature at the center of aluminum alloy surface increases and evaporation happens after the surface temperature at the center of aluminum alloy surface reaches boiling point and later the aluminum alloy material sustains in the status of equilibrium vaporization; the keyhole appears on the surface of the target, an increment of the keyhole, the maximum temperature at the center of aluminum alloy surface gradually moves inwardly. This research may provide the theoretical references to the understanding of the interaction between millisecond pulsed laser and many kinds of materials, as well as be beneficial to the application of the laser materials processing and military field.
Analysis and design of low noise column stage in CMOS ROIC for UV GaN focal plane array
Author(s):
Xiaojuan Li;
Yonggang Yuan;
Jing Xie;
Jiqiang Wang;
Ding Ma;
Ling Wang;
Xiangyang Li
Show Abstract
A novel column-stage structure of readout integrated circuit (ROIC) for GaN ultraviolet (UV) focal plane array (FPA) working in “solar-blind” band is proposed. The column stage has better drive capability, higher dynamic range, stable bias current and low impedance. The noise voltage of the column readout stage is discussed, which has been reduced by small-current driving, column-stage sample and hold and the technology of divided-output-bus. This research on low-noise ROIC is designed for weak-current UV FPA. It is designed, simulated and laid out using the 0.35um 2P4M CMOS 5V process. The clock rate operates at 8MHz. The simulation input current sets 0.01nA. The output swing is 2.6V and power consumption is 40 mW according to the measurement results.
Reviews of a Diode-Pumped Alkali Laser (DPAL): a potential high powered light source
Author(s):
He Cai;
You Wang;
Juhong Han;
Guofei An;
Wei Zhang;
Liangping Xue;
Hongyuan Wang;
Jie Zhou;
Ming Gao;
Zhigang Jiang
Show Abstract
Diode pumped alkali vapor lasers (DPALs) were first developed by in W. F. Krupke at the beginning of the 21th century. In the recent years, DPALs have been rapidly developed because of their high Stokes efficiency, good beam quality, compact size and near-infrared emission wavelengths. The Stokes efficiency of a DPAL can achieve a miraculous level as high as 95.3% for cesium (Cs), 98.1% for rubidium (Rb), and 99.6% for potassium (K), respectively. The thermal effect of a DPAL is theoretically smaller than that of a normal diode-pumped solid-state laser (DPSSL). Additionally, generated heat of a DPAL can be removed by circulating the gases inside a sealed system. Therefore, the thermal management would be relatively simple for realization of a high-powered DPAL. In the meantime, DPALs combine the advantages of both DPSSLs and normal gas lasers but evade the disadvantages of them. Generally, the collisionally broadened cross sections of both the D1 and the D2 lines for a DPAL are much larger than those for the most conventional solid-state, fiber and gas lasers. Thus, DPALs provide an outstanding potentiality for realization of high-powered laser systems. It has been shown that a DPAL is now becoming one of the most promising candidates for simultaneously achieving good beam quality and high output power. With a lot of marvelous merits, a DPAL becomes one of the most hopeful high-powered laser sources of next generation.
Optimal design of a new type space laser communication optical system
Author(s):
Pei-pei Yan;
Xiao-guo Deng;
Gang Li;
Kai Liu;
Jing Duan;
Qiu-sha Shan;
Kai Jiang;
Yu Zhang
Show Abstract
A design of a laser communications optical system with high transmitting and receiving performance is given. The traditional on-axis Cassegrain optical antenna has the default that the transmitting and receiving power decreased greatly because of the obscuration of the secondary mirror. Considering that the eccentric-pupil Cassegrain optical antenna is designed. The optical antenna system in transceiver has been designed by means of CODEV software. It improves the efficiency of transmitting and receiving power effectively. Its properties have been analyzed, such as gain, image quality, and transmission efficiency. Meanwhile, the materials of optical elements have been analyzed. The power decline curve has been obtained by means of the detailed analysis of antenna system in partial axis situation. The system includes transmitter channel, receiving channel and experiment channel. It can realize the functions of transmitter-receiver isolation and multi-light ways using dichroic mirrors and beam splitting prisms. The system volume and weight are reduced greatly. The complexity of conventional laser communication system is reduced enormously at the same time. It has important reference significance and application value.
The application of parallel computing technology in the data processing of the imaging spectrometer
Author(s):
Lei Zhang;
Jiao Bo Gao;
Meng Gao;
JunHu Xie;
He Min Meng;
Fang Zhang;
Yu-jie Zhao;
Xiangguo Xiao
Show Abstract
During the research of hyper-spectral imaging spectrometer, how to process the huge amount of image data is a difficult problem for all researchers. The amount of image data is about the order of magnitude of several hundreds megabytes per second. With the development of multi-core computer, parallel computing on multi-core computer is increasingly applied in large-scale data processing. In this paper, we give a detailed discussion of parallel computing technology, we also apply this technology to the data processing of hyper-spectral image data. Experimental results show that the speed of data processing is apparently improved. Our research has significant meaning for the engineering application of hyper-spectral imaging spectrometer.
Cistanches identification based on fluorescent spectral imaging technology combined with principal component analysis and artificial neural network
Author(s):
Jia Dong;
Furong Huang;
Yuanpeng Li;
Chi Xiao;
Ruiyi Xian;
Zhiguo Ma
Show Abstract
In this study, fluorescent spectral imaging technology combined with principal component analysis (PCA) and artificial neural networks (ANNs) was used to identify Cistanche deserticola, Cistanche tubulosa and Cistanche sinensis, which are traditional Chinese medicinal herbs. The fluorescence spectroscopy imaging system acquired the spectral images of 40 cistanche samples, and through image denoising, binarization processing to make sure the effective pixels. Furthermore, drew the spectral curves whose data in the wavelength range of 450-680 nm for the study. Then preprocessed the data by first-order derivative, analyzed the data through principal component analysis and artificial neural network. The results shows: Principal component analysis can generally distinguish cistanches, through further identification by neural networks makes the results more accurate, the correct rate of the testing and training sets is as high as 100%. Based on the fluorescence spectral imaging technique and combined with principal component analysis and artificial neural network to identify cistanches is feasible.