Image segmentation algorithm based on T-junctions cues
Author(s):
Yanyu Qian;
Fengyun Cao;
Lu Wang;
Xuejie Yang
Show Abstract
To improve the over-segmentation and over-merge phenomenon of single image segmentation algorithm,a novel
approach of combing Graph-Based algorithm and T-junctions cues is proposed in this paper. First, a method by L0
gradient minimization is applied to the smoothing of the target image eliminate artifacts caused by noise and texture
detail; Then, the initial over-segmentation result of the smoothing image using the graph-based algorithm; Finally, the
final results via a region fusion strategy by t-junction cues. Experimental results on a variety of images verify the new
approach’s efficiency in eliminating artifacts caused by noise,segmentation accuracy and time complexity has been
significantly improved.
A holographic display method combing amplitude of real picture and phase of hologram
Author(s):
Zhixiong Zhao;
Hai Liu;
Yunxiu Shui;
Lin Hu;
Y. Yang
Show Abstract
A holographic display method combing the Amplitude of real picture and the phase of hologram is proposed to improve holographic display. The hologram of the onion epidermal cells was recorded in the in-line digital holographic system. Then the phase unwrapping method was used to get the real phase of the epidermal cells of the onion. Intensity distribution of onion is recorded in CCD illuminated by LED. Based on that, Burch and Kinoform coding are utilized to make CGH (computer-generated hologram) using phase and intensity obtained before. Experiments indicate that clear reconstruction image and desirable display result are achieved with this novel method, providing a new idea for development of CGH display.
3D-shape reconstruction based on a sub-pixel-level mapping relationship between the camera and projector
Author(s):
Huijing Lin;
Haibo Liu;
Linshen Yao
Show Abstract
To some extent, the mapping relationship between the camera and projector images determines the precision of surface
reconstruction in digital close-range photogrammetry. In this paper, a new method is presented to achieve sub-pixel-level
mapping between the camera and projector images. Instead of mapping the stripe from the camera to the projector, which
is pixel-precision-based, a set of pixels that share the same decoded number were picked out on the camera images and
their barycenter was calculated to mapped onto the pixel on the projector images. In most cases, the calculation of the
barycenter is able to achieve sub-pixel precision. Compared with existing approaches based on the direct mapping of the
stripe on the camera image to the projector image, the proposed method is characterized by higher accuracy in mapping
the points and thus the surface reconstruction performance. The experimental results are presented to show the
effectiveness of the proposed method in the improvement of the accuracy of shape reconstruction.
Energy efficient integral imaging without flipped image using directional backlight
Author(s):
Jianlei Zhang;
Xiaorui Wang;
Danfeng Guo;
Ying Yuan;
Xiongxiong Wu
Show Abstract
Different from backlight for panel display, the backlight for integral imaging should be directional in order to improve the viewing quality. A method for eliminating the flipped image and improving the optical efficiency for integral imaging is proposed by using directional backlight with diffractive grating. The light from one elemental image reaching the neighboring elemental lens can be eliminated with directional backlight. The effect of the backlight angular divergence and pixel structure on crosstalk and the viewing angle is analyzed. Simulation and experiment show the validity of the proposed method.
Dynamic phase extraction in phase-shifted shearography
Author(s):
Yuanyuan Hou;
Jiancheng Xu
Show Abstract
Phase-shifted shearography needs to extract dynamic phase of the measured object after loading, so an algorithm for
dynamic phase extraction in phase-shifted shearography is proposed to analyze the speckle patterns with random phase
shifts. By using correlation method, the fringe patterns with random phase shifts are obtained from the speckle patterns
with random phase shifts. Then the dynamic phase distributions are extracted from one set of random phase-shifted
fringe patterns by principle component analysis. The experimental results show that the extracted phases are accurate and
efficient. The proposed method is non-iterative and has no strict requirement for the spatial-carrier frequency of fringe
patterns, so it is suitable for dynamic shearing speckle interferometry.
Research for gate drive technology based on image intensifier
Author(s):
Guangqiang Xu;
Baiyu Liu;
Yongsheng Gou
Show Abstract
In order to improve the dynamic range and the signal-noise ratio of the image intensifier, keep the flux of the screen of image intensifier constant. In the article, introduced a design of the switching power supply and tested its performance. Firstly, used a sampling amplifier amplify the feedback current signals. The feedback signals were converted into square wave signals through a digital circuit. Then, using the MOSFET in the post stage circuit produced high voltage and high speed adjustable square pulses. The frequency of the pulse is 1 kHz, the speed of the cutting edge is 20ns and the amplitude is 200V. The photoelectron emission time of the photocathode is short when the width of the high speed pulse is narrow for strong illumination. On the contrary, the time is long when the width is wide for weak illumination. The number of photoelectron is a constant no matter what kind of the illumination. It keeps the flux reaching the phosphor screen constant.
A push-broom compressive imaging system with situ calibration function for encoding mask
Author(s):
Lei Wang;
Zhengzheng Shao;
Jiying Liu;
Qianwen Nie;
Hui Jia;
Suian Dai;
Xiaofeng Wang;
Jubo Zhu;
Xiujian Li
Show Abstract
Compressive imaging（CI）can offer a versatile improvements for imaging systems, such as smaller compressed data volume and super-resolution. Among various methods to realize Compressive imaging, pushing encoding mask has attracted the most attention with its compatibility to the space remote sensing. However, complex pre- calibrations are usually needed for calibrating the encoding mask to achieve the measurement matrix for the image reconstruction. Herein, we design a pushing compressive imaging system which fixed with the function of situ calibration of the encoding mask. The pushing compressive imaging system was constructed, and the experimental results confirmed that the system had the ability for data compression and super-resolution. And above all, the system can avoid the complex pre-calibration, which makes the on-orbit calibration feasible. In the simulations, twice, three times and four times resolutions higher than the captured image’s resolution are performed respectively, which confirm that the method can improve the target image resolution based on the relative low resolution raw captured target images. Furthermore, by pushing the mask precisely which can be considered equivalent to the real pushing imaging, we have reconstructed the true super-resolution target image accurately based on the mask calibration and 6 captured pushing imaging frames.
Observation of the chain transformation process in magnetorheological fluids using micro-DHPTV
Author(s):
Hai Liu;
Zhixiong Zhao;
Lin Hu;
Yunxiu Shui;
Gang Zhu
Show Abstract
In the last years, several techniques have been developed for the measurement of the three velocity components in a fluid plane or volume.Digital holography particle tracing velocimetry(DHPTV)was applied to observe the chain transformation process of magnetorheological fluids (MR fluids) under an external magnetic field. With the help of correlation coefficient(CC)method[1], the focus plane of standard particle target was determined. The displacement of standard target mounted on a precise displacement measurement workbench was compared with the distance measured by difference of focal planes movement. Making use of a controlled rotating platform with constant revolving speed, the rotation speed of particles was obtained after extracting the coordinates from reconstruction images. The measured speed was compared with actual speed of particles,which can be worked out through rotation speed of platform. The transformation speed was measured when magnetic particle moved along with magnetic direction under an external magnetic field. The experiments showed that a visible part of 3D velocity field could be observed in the chain transformation process of MR fluids with DHPTV.
Research of an optimization design method of integral imaging three-dimensional display system
Author(s):
Hui Gao;
Zhiqiang Yan;
Jun Wen;
Guanwu Jiang
Show Abstract
The information warfare needs a highly transparent environment of battlefield, it follows that true three-dimensional display technology has obvious advantages than traditional display technology in the current field of military science and technology. It also focuses on the research progress of lens array imaging technology and aims at what restrict the development of integral imaging, main including low spatial resolution, narrow depth range and small viewing angle. This paper summarizes the principle, characteristics and development history of the integral imaging. A variety of methods are compared and analyzed that how to improve the resolution, extend depth of field, increase scope and eliminate the artifact aiming at problems currently. And makes a discussion about the experimental results of the research, comparing the display performance of different methods.
Hand and goods judgment algorithm based on depth information
Author(s):
Mingzhu Li;
Jinsong Zhang;
Dan Yan;
Qin Wang;
Ruiqi Zhang;
Jing Han
Show Abstract
A tablet computer with a depth camera and a color camera is loaded on a traditional shopping cart. The inside information of the shopping cart is obtained by two cameras. In the shopping cart monitoring field, it is very important for us to determine whether the customer with goods in or out of the shopping cart. This paper establishes a basic framework for judging empty hand, it includes the hand extraction process based on the depth information, process of skin color model building based on WPCA (Weighted Principal Component Analysis), an algorithm for judging handheld products based on motion and skin color information, statistical process.
Through this framework, the first step can ensure the integrity of the hand information, and effectively avoids the influence of sleeve and other debris, the second step can accurately extract skin color and eliminate the similar color interference, light has little effect on its results, it has the advantages of fast computation speed and high efficiency, and the third step has the advantage of greatly reducing the noise interference and improving the accuracy.
Research on feature extraction techniques of Hainan Li brocade pattern
Author(s):
Yuping Zhou;
Fuqiang Chen;
Yuhua Zhou
Show Abstract
Hainan Li brocade skills has been listed as world non-material cultural heritage preservation, therefore, the research on Hainan Li brocade patterns plays an important role in Li brocade culture inheritance. The meaning of Li brocade patterns was analyzed and the shape feature extraction techniques to original Li brocade patterns were advanced in this paper, based on the contour tracking algorithm. First, edge detection was made on the design patterns, and then the morphological closing operation was used to smooth the image, and finally contour tracking was used to extract the outer contours of Li brocade patterns. The extracted contour features were processed by means of morphology, and digital characteristics of contours are obtained by invariant moments. At last, different patterns of Li brocade design are briefly analyzed according to the digital characteristics. The results showed that the pattern extraction method to Li brocade pattern shapes is feasible and effective according to above method.
Depth image interpolation algorithm based on confidence map
Author(s):
Yutong Zhong;
Yu Wang;
Yan Piao
Show Abstract
TOF (time-of-flight) depth camera is a 3D imaging device that can obtain high-precision distance information. It is used to estimate 3D structure directly without the help of traditional computer-vision algorithms. However, it has some disadvantages such as generated a depth map with low resolution and it has large random noise. In order to overcome this limitation, we proposed a new method with combines the confidence map and use the interpolation operation to improve the resolution of the image. In the up-sampling process, we consider the relationship between distance information generated by TOF camera and the confidence map, through a novel method that based on the confidence value to weighted for the traditional nearest neighbor interpolation, bilinear interpolation and the bi-cubic interpolation algorithm, increase the weight of the depth information with high confidence value in every way. Then through the multi-directional changes of edge gradient, the pixel points of edge region to be optimize with the interpolation. Experimental results show that ours method can improve the resolution of the depth image and optimize the edge effect.
Orthoscopic 3D reconstruction using flexible ray tracing method in computational integral imaging
Author(s):
Dongying Li;
Yongri Piao;
Miao Zhang
Show Abstract
In this paper, we present a computational orthoscopic integral imaging reconstruction method by utilizing a flexible ray tracing algorithm to overcome the pseudoscopic problem. Compared to previous works, the proposed method can directly reconstruct orthoscopic 3D images through one step ray tracing process. Thus, a real, undistorted, orthoscopic 3D images can be reconstructed various distances without the magnification and overlap process of conventional CIIR. To show the feasibility of the proposed method, the preliminary experiments are carried out and the some experimental results are presented.
Resolution enhanced 3D photon counting integral imaging
Author(s):
Jianqiao Liu;
Yongri Piao;
Miao Zhang;
Peihua Li
Show Abstract
In this paper, we present a resolution enhanced 3D photon counting integral imaging system to improve the visual quality of the reconstructed 3D images. In order to solve the limitation of the visual quality cause by the photon starved condition, the statistical estimation algorithm based on the 3D imaging structure is proposed to estimate the high performance photon counting images. Additionally, synthetic aperture integral imaging is utilized for imaging and reconstruction in low light levels condition. Finally, the performance of the proposed method is verified relying on the precise experimental results.
Multi-focus elemental images fusion in integral imaging system
Author(s):
Xiaohui Wang;
Yongri Piao;
Miao Zhang
Show Abstract
In synthetic aperture integral imaging system, a camera array is employed to obtain multiple perspective images from a 3D scene. However, the imaging lens suffer from the limitation of depth of field which disallows a conventional integral imaging system to obtain full-focus elemental images. To solve this problem, we present a multi-focus elemental images fusion method to reconstruct resolution enhanced 3D integral images. In the proposed method, depth estimation and image registration are achieved to fuse full-focus elemental images. Then, the resolution enhanced 3D images are reconstructed by using full-focus elemental images. To verify feasibility of the proposed method, the preliminary experiments are carried out.
A high performance auto-stereoscopic display based on free-form surface backlight array and mix-teeth Fresnel lens
Author(s):
Kunyang Li;
Zhichao Wu;
Di Pan;
Yuqiao Xian;
Jiahui Wang;
Yangui Zhou;
Jianying Zhou
Show Abstract
An ultra HD, low crosstalk, high luminance uniformity, and wide field of view auto-stereoscopic display is demonstrated with the use of novel free-form surface backlight array (FFSBA) and mix-teeth Fresnel lens (MTFL) technology, in conjunction with a hybrid spatial and temporal control scenario. The luminance uniformity is shown to be higher than 95.3% even within a wide viewing angle, and the minimum achievable crosstalk can be as small as 2.2%. The moiré pattern is avoided by an equivalent anisotropic film (EAF).
Phase retrieval in two-step quadrature phase-shifting holography
Author(s):
Wenjing Zhou;
Caifu Zheng;
Hongbo Zhang;
Yingjie Yu;
Ting-Chung Poon
Show Abstract
This paper presents a simple and effective method, without the need for any additional recording of the intensity maps or tremendous iterative computations, to remove the complex zeroth-order term in the complex hologram for phase retrieval in two-step quadrature phase-shifting holography by utilizing the intensity in certain area in the complex hologram. We select a particular area in the complex hologram where there is negligible diffraction from the test sample to calculate the intensity. The calculated intensity value allows us to eliminate the complex zeroth-order term from the complex hologram. Exact phase distribution can then be reconstructed by using the new complex hologram without the zeroth-order and twin image noise. Experiment results have been performed to verify the effectiveness and feasibility of our proposed method.
Optical encryption of three-dimensional information based on integral imaging and ptychography
Author(s):
Yan Xing;
Zhao-Long Xiong;
Huan Deng;
Qiong-Hua Wang
Show Abstract
In this paper, we propose an optical method based on integral imaging(II) and ptychography to encrypt threedimensional( 3D) information with simple architecture. The 3D scene plaintext is encrypted by a camera array and double-random phase masks via ptychography to generate a series of diffraction intensity patterns as ciphertexts. Then, the decrypting process with ptychographic iteration and II reconstruction is employed to retrieve high-quality 3D images. Since scanning light probes and parameters of II can serve as secret keys that enlarge the key space, and elemental image array generated by the II pickup has redundancy property, the security of encryption scheme can be improved significantly. Also, the decrypted 3D images in our proposed method have high-quality. Preliminary experiments are carried out, and the results demonstrate the feasibility and robustness of our proposed method. Especially, this research is suitable for real large-size 3D scene.
Design of three-dimensional imaging system based on SFM
Author(s):
Hongfei Yang;
Xin Chen;
Peng Rao
Show Abstract
For the prospects of three-dimensional reconstruction technology based on structure from motion in engineering application, a high-resolution and visible band imaging system has been designed and implemented. It consists of a 5k × 5k CMOS focal plane array detector made by the ON-SEMI company, an optical system and an electronics system designed by ourselves. The electronics system takes FPGA as the control and drive processor chip and is divided into three parts: a power management module, a detector module and an image processing module, capable of finishing image compression and transmission. A sequence of images for the target of long distance away is obtained from the imaging system and the images after cropping and segmentation, aiming at reducing calculation and excluding some points irrelevant with the target during reconstruction process, are took as input of structure from motion. Seeds from the match points expand from sparse points to dense points and the initial model of reconstruction target is achieved. The experiment results show that the imaging system meet the requirement of three-dimensional reconstruction in engineering application and a new novel imaging system design of graded resolution based on bionics is proposed.
Optimizing display uniformity with a staggered backlight in an autostereoscopic display system
Author(s):
Quanquan Zhang;
Jiayi Chen;
Jieyong He;
Kunyang Li;
Haowen Liang;
Jiahui Wang
Show Abstract
In this paper, we propose a staggered design directional backlight system in an autostereoscopic display. Currently, one of the main deficiency of autostereoscopic display is low display uniformity in both horizon and depth direction. In order to optimized display unifomity, the system mainly employs a staggered backlight array designed by a trace-back algorithm and a light shaping diffuser. As result, the horizontal dark areas are fully compensated. Moreover, crosstalk of experimental system is as low as 0.9%.
Simulation based quantitative evaluation for display uniformity in a directional backlight auto-stereoscopic display
Author(s):
Jieyong He;
Haowen Liang;
Quanquan Zhang;
Shirui Feng;
Jiahui Wang;
Jianying Zhou
Show Abstract
In this article, we propose a quantitative evaluation for the display uniformity in a directional backlight system. Display uniformity is divided into two research aspects - static uniformity and motional uniformity. Factors influencing uniformity deterioration are then discussed in our evaluation. Furthermore, a visualized simulation based on ray-tracing model is proposed to analyze this display uniformity in quantitative depth. Optical distribution on the screen is obtained in this simulation to provide visualized results compared with the experimental results. Our work helps to fill the vacancy for the evaluation of display uniformity on directional backlight type 3D display.
3D Fresnel field computing method based on its propagation reversibility
Author(s):
Kai Zhang;
Xiangxiang Wang;
Shengxia Tan;
Chuan Shen;
Sui Wei
Show Abstract
There are many 3D data structures for computing diffraction field, the description based on 3D point-cloud is the elemental method of other descriptions, the diffraction field of 3D scene can be thought as the superposition of the diffraction field of each sampled light point and other descriptions can be thought as grouping with point-cloud by different way. The paper focuses on devising a computation method of 3D Fresnel field which is based on Fresnel diffraction field propagation reversibility. The proposed method combines the reversibility of Fresnel propagation and the requirement of sampling spacing by Nyquist criterion, i.e. to find the best space positions to optimize the number of sampling points and the reconstruction for the 3D Fresnel field. The method can be applied to reduce the computational complexity and improve computational efficiency.
Application of photoelectric 2D-turntable for aiming device baseline variation detection and optimization design for supporting framework of 2D-turntable
Author(s):
Xu Han;
Ming Liu;
Jun Ma;
Sheng Li;
Jia Liu;
Leimengting Zhang
Show Abstract
An application example of precision photoelectric 2D-turntable for aiming device baseline variation detection is proposed in this paper, the optical measurement method is also expounded and the design scheme of automatic digital photoelectric 2D-turntable with high precision is supported. Because the supporting framework is the key component and the main bearing component of two-dimensional turntable, its strength and stiffness will directly affect the adjustment accuracy and stability property, the variable density topology optimization is applied to optimize the structure of supporting framework. The quality of supporting framework reduces by 20%, the displacement of the center of shafting mass under gravity loads is less than 0.05mm. The experimental results indicate that adjustment error of the photoelectric 2D-turntable is less than 0.05mil, repetitive positioning accuracy is more than 0.01mil which meets the design requirements of high precision adjustment accuracy or stability.
Development of atmospheric pressure plasma torch for the fabrication of freeform optics
Author(s):
Xing Su;
Qiang Xin;
Yuanhang Liu;
Longguang Xia;
Bo Wang
Show Abstract
Freeform optics especially Continues Phase Plate, are greatly demanded in high power laser systems. Fabrication of them with high efficiency and low sub-surface damage becomes a major challenge. Atmospheric pressure plasma processing using radicals produced by plasma torch, which has strong potential for machining freeform optics with millimeter and sub-millimeter spatial resolution, is proposed. This paper presents a novel plasma torch designed for fabricating freeform optics. This integral compact torch is comprised of needle electrode and micro-hole electrode. Millimeter-scale plasma jet of different size can be obtained by changing the micro-hole electrode. To analyze the process distribution of process gas of the jet flow, flow simulation is performed using COMSOL Multiphysics software. A set of single factor experiments are conducted to reveal the relationship between removal characteristics and flow rate of He, CF4 and O2. The removal rate with adding O2 increases 7 times of that without O2, and the spectrum change of the plasma jet is observed. It indicates that O2 improves removal rate through consuming existing CFx to produce more F radicals. The removal rate and full width at half maximum (FWHM) of typical removal function is about 19 μm/min-2.2 mm and 18 μm/min-1.1 mm respectively.
3D shape measurement method based on the triangle pattern
Author(s):
Guoli Qu;
Chao Huang;
Yanjun Fu;
Bin Qian;
Fuwei Wang
Show Abstract
Binary pattern defocused projection is a promising method of measuring 3D shapes. However, deep or long-distance defocus prevents high-accuracy 3D measurement. The triangle pattern is preferred because of its slight defocus and ability to overcome the nonlinear gamma. Thus, a novel method combining triangle pattern slight defocus with phase shifting is proposed. The proposed method has two merits: (1) Compared with the sinusoidal pattern, the proposed method can overcome the nonlinear gamma. (2) Compared with the binary pattern, it has the advantage of slightly defocusing to an ideal sinusoidal pattern in a short distance. Thus, the measurement error caused by nonlinear gamma and deep defocus is reduced. The RMS error of the proposed method is <0.03 mm. Theory analysis and experiments demonstrate the feasibility and superiority of the proposed method.
Research on the magnetorheological finishing of large aperture off-axis aspheric optical surfaces for zinc sulfide
Author(s):
Yunfei Zhang;
Wen Huang;
Yongcheng Zheng;
Fang Ji;
Min Xu;
Zhixin Duan;
Qing Luo;
Qian Liu;
Hong Xiao
Show Abstract
Zinc sulfide is a kind of typical infrared optical material, commonly produced using single point diamond turning (SPDT). SPDT can efficiently produce zinc sulfide aspheric surfaces with micro-roughness and acceptable figure error. However the tool marks left by the diamond turning process cause high micro-roughness that degrades the optical performance when used in the visible region of the spectrum. Magnetorheological finishing (MRF) is a deterministic, sub-aperture polishing technology that is very helpful in improving both surface micro-roughness and surface figure.This paper mainly investigates the MRF technology of large aperture off-axis aspheric optical surfaces for zinc sulfide. The topological structure and coordinate transformation of a MRF machine tool PKC1200Q2 are analyzed and its kinematics is calculated, then the post-processing algorithm model of MRF for an optical lens is established. By taking the post-processing of off-axis aspheric surfacefor example, a post-processing algorithm that can be used for a raster tool path is deduced and the errors produced by the approximate treatment are analyzed. A polishing algorithm of trajectory planning and dwell time based on matrix equation and optimization theory is presented in this paper. Adopting this algorithm an experiment is performed to machining a large-aperture off-axis aspheric surface on the MRF machine developed by ourselves. After several times’ polishing, the figure accuracy PV is proved from 3.3λ to 2.0λ and RMS from 0.451λ to 0.327λ. This algorithm is used to polish the other shapes including spheres, aspheres and prisms.
Relation between sensor measurement and volumetric method in texture depth measurements
Author(s):
Huayang He;
Yishu Zhou;
Hongbo Guo
Show Abstract
Texture depth is defined as the deviations of the road surface profile from the datum plane. It is currently assessed by two methods--sensor measured texture depth (SMTD) and sand patch method (SPM). Many researchers did lots of experiments to study the correlation between these two methods, but ignored the waveform characteristic of the road surface profile. A mathematical model of the road surface profile was built in this paper to calculation of texture depth and compare the two methods. This paper studied the statistical relationship between sensor measured texture depth and sand patch method in different waveform characteristics, and found out that the frequency is the main factor. The results show that the two methods have excellent correlation at the same frequency, and the correlation coefficient R2 is equal to 1. Plates with same frequency were designed to conducted comparison experiments. The result verify the above conclusion. It shows good correlation between the laser detection technology and the volumetric patch technique. Since manufacturers mainly use sand patch method for experiments, the result provides a theoretical basis and technical support for factory inspection. Also, it can be used to get the characteristics of the pavement structure in return.
Research of TIR LED collimation system based on freeform
Author(s):
Hui-fu Zhao
Show Abstract
In order to collect a wide angle range light to receive the collimating beam of a small divergence angle, a highly efficient, compact, TIR collimating system has been designed and optimized. The collimating system adopts a hybrid structure with TIR style. First, calculate the initial structure of the collimating system according to Snell’s law and equal focal length principle. Then optimize the initial structure using Lighttools optical design software. Finally, the best LED collimating system has been successfully designed. According to the results of the design, the semi-diameter of the TIR collimating system is 20mm, the diameter is 25mm. The collimating angle is 1.5°. With the light absorption loss of the material and reflection loss of the interface have already been fully considered，the light energy utilization rate is as high as 89.5%. The initial structure of TIR-type LED collimator is designed by Snell’s law and equal focal length principle, and then it is optimized by the Lighttools optical design software, so that light energy utilization ratio and uniformity of illumination in the target surface are improved. In addition, TIR-type collimating system, which is small and easy to use, not only has a high light energy utilization ratio but also a compact structure.
Design of a novel nonimaging Fresnel concentrator with high uniformity
Author(s):
Hui-fu Zhao;
Yu Chen
Show Abstract
The cost of photovoltaic power generation can be saved and efficiency will be improved by the concentration optics system. However, the non-uniformity of illumination distribution on the photovoltaic cells of the current Fresnel concentrators will reduce the photoelectric conversion efficiency and decrease the service life of the cell even damage the cell. This paper presents the design and simulation a novel nonimaging Fresnel concentrator, then comparatively analyses the performances of the conventional Fresnel concentrator. The novel nonimaging Fresnel concentrator has been design according to the diffused focal points method to improve optical efficiency and illumination uniformity. The novel Fresnel concentrator achieves high concentration efficiency 82.20%, and high uniformity 89.23% in the scope ±4mm of the concentration spot which can improve photoelectric conversion efficiency of photovoltaic cells and prevent the photovoltaic cells from being damaged.
Analysis and design of functional micro/nano structured surfaces
Author(s):
Zhenzhen Xu;
Lingbao Kong;
Min Xu
Show Abstract
In recent years, more and more attention has been paid to the bionic structure and functional materials. The theoretical research and fabricating ways of the Super-hydrophobic surface have sound achievements. However, the existing methods largely depend on the precision of the equipment and complex chemical substances, and it is hard to ensure the consistence of the material surface. Therefore, construction of microstructure on the surface of the material by using the method of mechanical processing to make the scale of the Super-hydrophobic surface to promote the popularization and application of Super-hydrophobic surface is of great significance. In order to put forward the innovative microstructure and to provide theoretical basis for the subsequent mechanical processing, based on the analysis of the classical theory of Super-hydrophobic, the super-hydrophobic film was by sol gel method. To explore the effects of different ratio of materials on the hydrophobicity, a micro/nano-structured super-hydrophobic coating was obtained by coating a film improved by hexamethyldisilazane (HMDS) after a film improved by polyethylene glycol (PEG) was coated. The microstructure of bilayer films is analyzed, and the double-layer film structure is simplified to design two kinds of microstructure models. For the design of the two models based on the Wenzel and Cassie equations, a roughness factor is adopted to establish the quantitative relationship between the contact angle and the microstructure parameters, and the microstructure parameters is also analyzed by using MATLAB software, and hence the optimized microstructure parameters is obtained.
Preparation of antireflective films on small square KH2PO4/KD2PO4 crystals by spin coating
Author(s):
Bin Shen;
Haiyuan Li;
Liyi Zhao;
Yongxing Tang
Show Abstract
Modified antireflective thin films for optical crystals are developed by sol gel chemistry. Hexamethyldisilazane is added
to silica sol to prepare modified sol by the Stöber method. The particle size distribution of the modified sol is found to
have good uniformity, with an average particle diameter of about 42.14 nm. This sol can be used to prepare antireflective
films with low refractive index of about 1.2. Homogeneous double layered films of antireflective and moisture resistant
properties are demonstrated to coat small square sized KH2PO4/KD2PO4 crystals through a combination of dip and spin
coating. The modified antireflective films display residual reflectivity close to zero, and laser induced damage threshold
of 10.9 J/cm2 (pulse wavelength: 355nm, pulse width: 3ns) measured by raster scan method.
Investigation on the temperature rise and thermal stress of edge-cladding
Author(s):
Junjiang Hu;
Tao Men;
Youkuo Chen;
Lei Wen;
Hong He;
Jingping Tang;
Biao Wang;
Shubin Chen;
Wei Chen;
Lili Hu
Show Abstract
Absorption of edge-cladding Cu-glass for the strong amplified spontaneous emission of Nd-glass disk will produce
a large rise for the temperature and thermal stress near the cladding interface between Cu-glass and Nd-glass.
According to the calculation for amplified spontaneous emission of Nd-glass and thermal stress along the thickness
of Cu-glass, which is produced in our lab, the relations among temperature rise, thermal stress, CuO doping
concentration and thickness of cladding Cu-glass, are discussed in detail. If using 0.10% CuO doping instead of
1%, which was used in the previous time, the maximum temperature will decrease from 46K to 13K and the thermal
stress will decrease from 4.0 MPa to 0.8 MPa. Our edges cladding experimental results, obtained by the low CuO
concentration edge cladding glass, are consistent with the inferences and validated in the SG series laser systems.
Influence of dielectric protective layer on laser damage resistance of gold coated gratings
Author(s):
Kepeng Wu;
Ping Ma;
Yunti Pu;
Zhilin Xia
Show Abstract
Aiming at the problem that the damage threshold of gold coated grating is relatively low, a dielectric film is considered on the gold coated gratings as a protective layer. The thickness range of the protective layer is determined under the prerequisite that the diffraction efficiency of the gold coated grating is reduced to an acceptable degree. In this paper, the electromagnetic field, the temperature field and the stress field distribution in the grating are calculated when the silica and hafnium oxide are used as protective layers, under the preconditions of the electromagnetic field distribution of the gratings known. The results show that the addition of the protective layer changes the distribution of the electromagnetic field, temperature field and stress field in the grating, and the protective layer with an appropriate thickness can improve the laser damage resistance of the grating.
Study on KDP crystal raw material batch production and purification technology in strong laser application
Author(s):
Zhengzhou Liu;
Wenwei Sun;
Wei Wang;
Jinfeng Gu;
Xiao-yan Gu;
Xinguang Xu;
Xun Sun
Show Abstract
According to a study in KDP crystal growth and performance, it’s found that the impurity content of potassium dihydrogen phosphate crystal by batch production affects directly the growth rate and optical properties of the KDP crystal. Through research on a variety of materials production methods, it’s found that there’re seldom reports on impurity removing technology by physical methods. This project studied the key process parameters and control factors on the batch production of potassium dihydrogen phosphate raw material. By modification and adjusting the process parameters, the quality of KDP crystal materials is improved.
The influence of subsurface damage’s micro crack on the optical properties of the optical components
Author(s):
Huapan Xiao;
Hongfeng Chen;
Hairong Wang;
Guanglong Fu;
Zhi Chen
Show Abstract
The subsurface damage (SSD) introduced by manufacturing procedures are the important factors affecting mechanical
and optical properties of the high-precision optical components. In this paper, we investigated the relationships between
the size of SSD’s micro crack and optical properties by studying on the influence of grinding process parameters
(average abrasive size, grinding force, wheel speed, grinding depth) on the optical properties (transmittance, absorbance,
reflectance) of high-precision optical components first, and then determining the micro crack’s size under the grinding
process parameters. Results indicate that with the increase of average abrasive size, grinding force or grinding depth, the
transmittance of high-precision optical components decreases while the absorbance and reflectance increase. However,
as the wheel speed increases, the transmittance of high-precision optical components increases while the absorbance and
the reflectance decrease. Combining these results with the influence of grinding process parameters on the size of micro
crack, it can be found that with the increase of micro crack’s size, the transmittance will decrease, while the absorbance
and the reflectance will increase.
Exploration of problems in the process of metallization of quartz
Author(s):
Xinqiang Cui;
Xiangchao Guo;
Jia Chen;
Haibing Li
Show Abstract
Since the difference between the film and the quartz, there are problems in metallization process such as low bonding
strength, poor wettability and the film stress; combined with the actual situation, carried out a series of exploration of the
above problems, take different measures to solve the practical problems.
Industrialization progress of high-purity hafnium for optical components
Author(s):
Lijun Wang;
Shunli Zhang;
Jiandong Zhang;
Yang Chen;
Jiaqing Peng
Show Abstract
Hafnium oxide, hafnium crystal bar and high-purity hafnium were prepared using extraction separation, reduction, electrolytic refining, iodide refining and electron beam melting process by General Research Institute for Nonferrous Metals. A hundreds-kilogram production line has been built. The purity of the high-purity hafnium was Zr/(Zr+Hf) <0.3wt% and Zr+Hf>99.99wt%, which enables a high laser induced damage threshold.
Study of the thermal damage mechanism in the discharge of high power xenon lamp
Author(s):
Xiangchao Guo;
Jianjun Liu;
Haibing Li;
Ruihua Wu;
Ruoyan Shao;
Hairong Liang;
Wenzheng Lin
Show Abstract
With method of fixing wire in the high power pulsed xenon lamp tube, an experimental device of double lamp series
was established to simulate the actual working environment of the xenon lamp. The experimental results show that the
thermal damage with the pre delay time of 150μs is much more serious compared with the pre delay time of 250μs. The
reason could be that the metastable particles formed by pre discharge are uneven with the former. The tube pale first
appears near the left lamp anode and the right lamp cathode. The possible reason is that bifurcates and shifts of the
plasma discharge channel are affected by the wire. The test results show that the main reason of thermal damage is that
the temperature of discharge plasma is uneven inside the tube. By improving the structure of the lamp box and
optimizing the pre delay time, the discharge plasma temperature can be decreased for the avoidance of the thermal
damage.
Fabrication of the polarization independent spectral beam combining grating
Author(s):
Quan Liu;
Yunxia Jin;
Jianhong Wu;
Peiliang Guo
Show Abstract
Owing to damage, thermal issues, and nonlinear optical effects, the output power of fiber laser has been proven to be limited. Beam combining techniques are the attractive solutions to achieve high-power high-brightness fiber laser output. The spectral beam combining (SBC) is a promising method to achieve high average power output without influencing the beam quality. A polarization independent spectral beam combining grating is one of the key elements in the SBC. In this paper the diffraction efficiency of the grating is investigated by rigorous coupled-wave analysis (RCWA). The theoretical -1st order diffraction efficiency of the grating is more than 95% from 1010nm to 1080nm for both TE and TM polarizations. The fabrication tolerance is analyzed. The polarization independent spectral beam combining grating with the period of 1.04μm has been fabricated by holographic lithography - ion beam etching, which are within the fabrication tolerance.
Investigation of the chemical composition and atomic emission spectroscopy of fused silica in CF4 plasma processing
Author(s):
Huiliang Jin;
Caixue Tang;
Nan Zheng;
Wenhui Deng;
Xianhua Chen
Show Abstract
The surface chemical composition and atomic emission spectroscopy of F atoms and CF2 molecules involved in the
processing of Atmospheric Pressure Plasma Jet (APPJ) produced from CF4 precursor has been explored. The XPS
spectra illustrated that small amount of radicals including C-CFn and CF-CFn could be introduced onto the fused silica
surface during the CF4 plasma process, the fluorocarbon radicals were generated during CF4 plasma ionization.
Moreover, the relative concentrations of excited state species of F atoms and CF2 molecules, which play significant role
in remove and fluorocarbon radicals, were acquired for CF4 plasma. The densities of F atoms increased dramatically with
increasing applied RF power, whereas CF2 molecules decreased monotonically over the same power range, the
subsequent electron impacted decomposition of plasma species after CF4 precursor fragmentation. The spectrum of the F
atoms and CF2 molecules fallowed the same tendency with the increasing concentration of gas CF4, reaching the
maximum at the 20sccm and 15sccm respectively, and then the emission intensity of reactive atoms decreased with more
CF4 molecules participating. Addition certain amount O2 into CF4 plasma resulted in promoting CF4 dissociation, O2 can
easily react with the dissociation product of CF2 molecules, which inhibit the compound of the F atoms, so with the
increasing concentration of O2, the concentration of the CF2 molecules decreased and the emission intensities of F atoms
showed the maximum at the O2/CF4 ratio of 20%. These results have led to the development of a scheme that illustrates
the mechanisms of surface chemistry reaction and the affection of plasma parameters in CF4 plasma systems with respect
to F and CF2 gas-phase species.
Study on the influence factors of the mid-spatial-frequency wavefront PSD1 error for large-aperture mirrors
Author(s):
Jin Luo;
Qian Wu;
Feng Pan;
Yaowei Wei
Show Abstract
With the progress of high power laser system, the specifications of the large-aperture optics on the
low-spatial-frequency wavefront, mid-spatial-frequency wavefront, high-spatial-frequency wavefront
all meet stricter requirements. To the mid-spatial-frequency wavefront, it has been researched less than
others. The influence factors of the mid-spatial-frequency wavefront PSD1 error for large-aperture
mirrors are analyzed in this work. The results show that the influence factors of the
mid-spatial-frequency wavefront is different with the low-spatial-frequency wavefront. PV error
depends on the peak and vale of film surface，Grms error is affected by the big amplitude wave of film
surface, and PSD1 error is mainly caused by the small frequency wave of film surface. So it is the key
to controlling the PSD1 error for large-aperture mirrors that reducing small frequency wave of film
surface.
Effect of substrate thickness on properties of protective antireflection a-C:H films deposited by PECVD
Author(s):
Kaihu Fu;
Chengkui Zu;
Yangli Jin;
Yang Qiu;
Bin Han
Show Abstract
The a-C:H films were deposited on glasses with different substrate thickness (rising from 2mm to 26mm) by Plasma Enhanced Chemical Vapor Deposition (PECVD). The effect of substrate thickness to the deposition rate, structural variations of films was investigated by surface morphology device and Raman spectroscopy. The results show that the deposition rate, H contents of films increase, meanwhile, I(D)/I(G), G peak position decrease and all of them show strong linear relation with the increasing substrate thickness. The a-C:H film with the highest thickness presents the highest deposition rate (37.7nm/s), nanohardness (20.2GPa), elastic modulus (118.8GPa) and lowest friction coefficient (0.266).
The influence of defects on LIDT in fused silica by 248nm laser pulses
Author(s):
Hui Wang;
Zhixing Gao;
Bo Fu;
Zhufeng Shao;
Yufen Wang
Show Abstract
The laser damage character of fused silica is studied experimentally. Firstly the distribution of the defects is presented.
Furthermore, the relevancy of the laser damage character and the defects is discussed. Finally, the fluorescence of
damage-occurring is explained. From the result, the way to ameliorate the laser damage character by controlling the
defects is given.
Study on the laser irradiation characteristics of Al/Mg fuel-rich propellant at lower ambient pressures
Author(s):
Hua-jin Lai;
Xiong Chen;
Chang sheng Zhou;
Heng sheng Xiang
Show Abstract
An experimental study of the ignition and combustion characteristics of Al/Mg fuel-rich propellant at lower ambient
pressures was performed. Measurements were obtained in a sealed vessel capable of reaching pressures as low as 0.1 atm
with the application of vacuum pump. The ignition delay time was obtained by photodiodes which monitor the laser signal
and flame signal; the linear burning rate of propellant was obtained by processing the continuous high-speed video images.
The experimental results show that the reduction in pressure caused a longer ignition delay time, this dependence will get
weaker as the externally applied heat flux increased; the linear burning rate reduced with the reduction of pressure, even
reduced about 47% at 0.1atm compared to constant pressure.
Preparation and damage characteristics of broad bandwidth HR films for picoseconds laser system
Author(s):
Guoyun Long;
Yaoping Zhang;
Junqi Fan
Show Abstract
High reflection films for 800nm picoseconds laser system requires broad bandwidth, which is usually about ±50nm, or even to ±70nm, and a high laser damage threshold is needed at the same time. Multilayer dielectrics using three materials Nb2O5/SiO2-HfO2/SiO2 were fabricated by electron beam evaporation. Benefit from its high refractive index of Nb2O5 and the high damage threshold of HfO2 films, the multilayer dielectrics were prepared successfully, which have more than 99.5% reflectance within bandwidth larger than 140nm around the center wavelength of 800 nm. The laser damage characteristics of the films at 150ps, 1Hz were studied, and the damage mechanism was analyzed.
Development of key technologies in the fabrication of large aperture off-axis wedge focusing lens
Author(s):
Xian-hua Chen;
Hua-dong Yu;
Bo Zhong;
Rui-qing Xie;
Lian Zhou
Show Abstract
In order to achieve the high precision fabrication of the large-aperture off-axis Wedged Focus Lens (WFL) for high
power laser device, the involved fabrication technologies including the ultra precision grinding, the high efficiency
polishing and the deterministic polishing, have been explored in this paper. Firstly, based on the configuration
characteristic of WFL, the parallel grinding theory and the calculation method of CNC program were introduced.
Secondly, the main factors affecting the removal efficiency were investigated and analyzed by orthogonal approach
experiment in the high efficiency polishing process, which can be used for the quality control. Then, the methods for
maintaining the stability of removal function and restraining the surface ripple were investigated during deterministic
polishing process. Finally, a 430mm×430mm off-axis Wedged Focus Lens was manufactured using the above
technologies, and the results indicated that, after polishing, the P-V, RMS, GRMS, PSD RMS1, PSD RMS2 and Rq are
0.097λ, 0.012λ (λ=632.8 nm), 5.851 nm/cm, 2.325 nm, 0.541 nm and 0.21 nm, respectively, which meet the requirement
of high power laser device. Consequently, the effectiveness of the proposed key technologies is proved.
The research progress of large-aperture fused silica for high power laser
Author(s):
Zhufeng Shao;
Yufen Wang;
Zaikui Xiang;
Chuandong Rao
Show Abstract
Because of its excellent optical performance, the fused silica is widely used in laser industry. In addition, the fused silica can withstand high power laser, due to its pure component, and the performance is most outstanding within all types of glasses. So fused silica can be used for optical lens in high power laser field.
From the manufacturing process stand point, the fused silica can be categorized to four types: type Ⅰ, type Ⅱ, type Ⅲ, and type Ⅳ. The fused silica of type Ⅰand type Ⅱ is made through melting silica sand in graphite furnace or oxyhydrogen flame. There are many defects in these types of fused silica, for example, the air bubbles, inclusions and metallic impurity. The other two types are made by synthetic reaction of SiCl
4 with water in oxyhydrogen or plasma flame. Both type Ⅲ and Ⅳ have excellent performance in transmittance and internal quality. However, type Ⅳof fused silica has disadvantage in small aperture and overall high manufacturing cost.
Take the transmittance and internal quality into consideration, the type Ⅲ fused silica is the most suitable for large-aperture lens, and can withstand high power laser. The systemic studies of manufacturing process were done to improve the performance of type Ⅲ fused silica in various areas, for instance, the optical homogeneity, the stress birefringence, the absorption coefficient and the damage threshold. There are four steps in manufacturing process of type Ⅲ fused silica, ingot production, reshaping, annealing and cold-working. The critical factors of ingot production, like the flame of burner and the structure of furnace, were deeply studied in this paper to improve the performance of fused silica.
On the basis of the above research, the performance and quality of the fused silica measured up to advanced world levels. For instance, the result of optical homogeneity can be controlled to 2～5 ppm, the stress birefringence is better than 4 nm/cm, the absorption coefficient is about 5.971ppm cm
-1 (1ω), the damage threshold is greater than 80, 25 and 23 J/cm
2 with the wavelength at 1064, 532 and 351nm respectively, the bandwidth used for measuring is 3ns.The fused silica has already been used in the area of high power laser facilities, aerospace industry, primary lens of interferometer based on its excellent performance.
Effect of oxygen flux on stress and optical properties of Ta-2 O-5 using ion-beam sputtering
Author(s):
Qi Yu;
Jun-qi Fan;
Chun-lin Guan
Show Abstract
The ion-beam sputtering deposition is a good technique for making low scattering coatings. In this work, the Ta2O5 thin films as the oxygen flux (15-35sccm) were prepared on the K9 glass using the single ion-beam sputtering. As the oxygen flux increased, the thickness of films with the same deposited time decreased from 936.67nm to 837.87nm. The refractive index was 2.075 in 1000nm at 30 sccm. The stress increased along with the increasing of oxygen flux. In the work, the compressive stress increased from 319.55 Mpa to 410.92 Mpa.
Study on the long-term stability of the ICP-MS fixed sample testing
Author(s):
Li Xiao;
Jun Ma;
Qi Zheng;
Hao-yun Chen;
Wen-wei Sun;
Zheng-zhou Liu;
Xiao-yan Gu
Show Abstract
This article studies the long-term stability of Na、Mg、Cr、Mn、Fe、Co、Cd、Ba、Pb in the matrix effect of potassium dihydrogen phosphate tested on ICP-MS Model X-series II manufactured by ThermoFisher. The test result proves good long-term stability and reliable analysis of the instrument.
Experimental research of the deterministic controlling process of surface figure in the large-aperture annular polishing
Author(s):
Minghong Yang;
Jianda Shao;
Xueke Xu;
Aihuan Dun;
Lunzhe Wu;
Yan Zhang;
Jun Cao;
Yang Zhang;
Zhe Wang
Show Abstract
The response characteristics of the pitch polishing pad under the pressure of conditioner is the key factor which affect the control efficacy of surface figure in annular polishing. The effect of the environmental temperature and humidity, rotation speed of the pad, uploading ratio and eccentricity of the conditioner on the response characteristics of pitch polishing pad were experimental researched. To this aim, a control system of the environmental temperature and humidity on the 2.8m-aperture annular polishing machine is established. The control precision of the local environmental temperature upon the pad is up to ±0.1℃, and the control precision of humidity is up to ±1% RH. The experimental results indicate that the matching degree of the pad and the conditioner decides the changing rule of the surface figure of workpiece with the eccentricity of the conditioner. The new adjustable parameters including the environmental temperature and humidity and the uploading ratio of the conditioner were introduced to change the matching degree and improve the controllability of the of the surface figure. Under the optimized process, the long-term stability of the surface figure of the meter-scale optical element is realized using the 2.8m annular polishing machine, which is an important step for the final realization of the deterministic processing in the large-aperture annular polishing.
Measurement of high accuracy flatness using a commercial interferometer
Author(s):
Yuchen Li;
Xueyuan Li;
Quanzhao Wang;
Sen Han;
Shouhong Tang;
Quanying Wu;
Linghua Zhang
Show Abstract
Higher accuracy of optical surface measurement is needed with the rapid development of optical industry and technology, especially in the field of optical manufacture and optical metrology. Fizeau interferometery is widely recognized as one of the most important measurement techniques currently in use. Results of the Fizeau interferometeric testing contain the reference surface errors and test surface errors. The test accuracy is restricted by the error of reference surface. As a result, so-called absolute flatness testing technology must be used to eliminate the system error such as reference surface error and higher accuracy of the surface profile testing. In this paper, the theory formula of even and odd functions is deduced, and the method are programmed for simulation. Based on HOOL phase-shifting interferometer, experiments are done to achieve high accuracy flatness measurement. The experiment shows that with high-accuracy interferometer, absolute flatness testing technology can effectively calibrate reference surface and improve the accuracy of flatness surface testing. An important result of this experiment is that the accuracy of the test surface can be reached λ/50.
High efficiency 878.6nm LD end-pumped pulse burst Nd:YVO4 laser
Author(s):
Xudong Li;
Yiping Zhou;
Renpeng Yan;
Xin Yu;
Deying Chen;
Zhongxiang Zhou
Show Abstract
A high-efficiency, high-repetition-rate burst-mode 1064 nm laser under pulsed 878.6 nm laser diode pumping is demonstrated. Pulses at repetition rates ranging from 10 kHz to 100 kHz are produced during the time period of 1 ms pumping duration by using an acousto-optical Q-switch. The maximum pulse burst energy of 44 mJ at 10 kHz is obtained at the incident pump power of 108.5 mJ, yielding an optical-to-optical efficiency of 40.5%. The shortest pulse width at 10 kHz is 9.4 ns at the maximum pump energy of 108.5 mJ. The peak powers are estimated to be ~468.1 kW and 30.1 kW at 10 kHz and 100 kHz in the burst-mode oscillator.
Optical design of portable nonmydriatic fundus camera
Author(s):
Weilin Chen;
Jun Chang;
Fengxian Lv;
Yifan He;
Xin Liu;
Dajiang Wang
Show Abstract
Fundus camera is widely used in screening and diagnosis of retinal disease. It is a simple, and widely used medical equipment. Early fundus camera expands the pupil with mydriatic to increase the amount of the incoming light, which makes the patients feel vertigo and blurred. Nonmydriatic fundus camera is a trend of fundus camera. Desktop fundus camera is not easy to carry, and only suitable to be used in the hospital. However, portable nonmydriatic retinal camera is convenient for patient self-examination or medical stuff visiting a patient at home. This paper presents a portable nonmydriatic fundus camera with the field of view (FOV) of 40°, Two kinds of light source are used, 590nm is used in imaging, while 808nm light is used in observing the fundus in high resolving power. Ring lights and a hollow mirror are employed to restrain the stray light from the cornea center. The focus of the camera is adjusted by reposition the CCD along the optical axis. The range of the diopter is between -20m-1 and 20m-1.
Study on MMW radiation characteristics and imaging of stereoscopic metal targets
Author(s):
Jing Liu;
Guangfeng Zhang;
Luyan Zhou
Show Abstract
The radiation characteristics in millimeter-wave band of the metal objects are complicated particularly those with complex three-dimensional structures. The complicated electromagnetic environment, in which the stereoscopic metal objects reflect the radiation energy in all directions with arbitrary incident angles, makes this problem even more challenging. In this paper, the surface panel method and the ray tracing theory are used to analyze the bins of the stereoscopic metal targets surface and their corresponding radiation sources in the reflection path. In addition, in 3mm band the radiometric images of the metal ball and the metal column are given by practical measurements. By comparing the single radiation scanning curves of the selected metal targets, the influence of the three-dimensional structures on the brightness temperature was analyzed and verified. Furthermore, the differences of the radiation patterns of different stereoscopic structures are also summarized.
Synchrotron radiation diffraction enhanced imaging of carbon fiber composites
Author(s):
Jingzheng Wang;
Jian Fu;
Xianhong Shi;
Qingxi Yuan;
Wanxia Huang;
Kai Zhang;
Peiping Zhu;
Baihong Jiang
Show Abstract
Carbon fiber composites have been wildly used in aerospace industry due to the excellent performance. However, the research on defect evolution law and the performance analysis have been limited by the lack of effective tools. Two kinds of computed tomography (CT) slice images of carbon fiber composites, x-ray attenuation contrast and phase contrast, were obtained with the diffraction enhancement imaging (DEI) device at Beijing Synchrotron Radiation Facility (BSRF). The structure details and the defects in the sample could be clearly distinguished from the image. Moreover, phase contrast CT provides higher contrast and can identify the defects difficult to be recognized in attenuation contrast CT. DEI provides a method for in-situ observation of the carbon fiber composites and would be a valuable tool for the development of carbon fiber composite material.
Development of synchrotron radiation computed laminography for plate-shell structures
Author(s):
Xianhong Shi;
Jian Fu;
Jingzheng Wang;
Qingxi Yuan;
Wanxia Huang;
Kai Zhang;
Peiping Zhu;
Baihong Jiang
Show Abstract
With the progresses of material sciences and technologies, carbon fiber composite shell-plate structures have been widely used in aerospace industry. Suffering from the drastic change of penetration thickness during the 360°scanning, conventional computed tomography (CT) is difficult to be applied to this kind of structures with a big length-width-thickness ratio, and not easy to implement the defect detection and the performance analysis. Based on the existing diffraction enhanced imaging (DEI) device at Beijing Synchrotron Radiation Facility beam-line 4W1A, a new computed laminography (CL) scanning system was designed and developed. It was integrated with the DEI device to form a synchrotron radiation DEI-CL system for plate-shell structures. Within this system, the components such as light source, detector and turntable and the working principle were discussed in detail. The experiment results of a decimeter-scale carbon fiber composite laminate sample validate the developed scanning system.
A comparative study of x-ray phase micro-tomography: grating based technique vs. high-energy propagation based technique
Author(s):
Huiqiang Liu;
Xizeng Wu;
Tiqiao Xiao
Show Abstract
Among the X-ray phase contrast imaging (XPCI) techniques, both propagation-based and grating-based micro-tomography recently dominate the non-destructive three-dimensional inner-structure measurement in biomedical research, especially for visualizing tiny density variations in soft tissues and organs. In order to quantitatively evaluate the advantages and disadvantages of both techniques for comprehensive application through carrying out a comparison study of high energy propagation-based micro-tomography with generalized phase-and-attenuation duality (PAD) phase retrieval and Talbot grating interferometer-based micro-tomography, implemented with two biomedical specimens, mouse fetus and rat brain, on the basis of synchrotron radiation facility. We find that the grating-based micro-tomography is superior in the contrast-to-noise ratio (CNR) or the mass density resolution, and inferior in the spatial resolution (SR), compared with that of propagation-based micro-tomography. We found that for achieving a given CNR, the grating-based micro-tomography applies about 1.5 times radiation dose involved as compared to the propagation-based micro-tomography with PAD phase retrieval. Additionally, the complex coherent degrees of light source related to the both techniques were duly taken into account in the analysis of their SR comparison. Finally, the mass density distribution of soft biomedical specimens can be estimated using our presented method preliminarily. Our work gives indications for applications and developments of phase sensitive micro-tomography for soft biomedical specimens and low-Z materials.
Improved reverse projection method for large refraction angle in grating-based x-ray phase contrast imaging
Author(s):
Wenbin Wei;
Zhao Wu;
Chenxi Wei;
Yue Hu;
Gang Liu;
Yangchao Tian
Show Abstract
Grating-based x-ray phase contrast imaging has attracted significant attentions in the past years due to its capability in achieving x-ray phase contrast imaging with low brilliance source. The reverse projection (RP) method is a novel fast and low dose information extraction approach, which bases on the linear approximation of the shifting curve around its half-slope. However, when the refraction angle is beyond the linear range of the shifting curve, the extracted information is no longer credible. In this paper, we present an improved retrieval method by calculating an inverse function. Compared with the original retrieval method, our method does not rely on the first order approximation, and thus is suitable for large refraction angle. Theoretical derivations and numerical simulations are performed to confirm the accuracy of the method.
A sCMOS camera and its tests for focal plane metrology and PSF centroiding experiment
Author(s):
Haitao Li;
Baoquan Li;
Yang Cao;
Ligang Li;
Jianfeng Yang;
Wei Ge;
Baogang Lv;
Jinyou Tao
Show Abstract
In this paper, the feasibility of a sCMOS camera for astrometric exoplanet detection space mission was evaluated and the evaluation methods were also studied. A 2k x 2k single-chip sCMOS camera was installed on the metrology testbed for the space mission. The pixel size of the detector is 11μm, corresponding to 1.86 arcsec on the focal plane. The sCMOS camera runs with a electronic rolling shutter. We tested the performance of the camera in detail, including the gain, linearity, readout noise, dark current, pixel response non-uniformity, etc.. The data acquisition performance for the pseudo-star and the interference fringes are also studied.
The study of radiation damage of yeast cells in Cryo-soft x-ray tomography
Author(s):
Liang Guo;
Yong Guan;
Chenxi Wei;
Yue Hu;
Yangchao Tian;
Gang Liu
Show Abstract
Cryo soft X-ray tomography (Cryo-SXT) is a valuable tool for high-resolution three dimensional (3D) imaging of cells in near-native preservation state. Cryo-immobilization of cells based on rapid cryogenic freezing is crucial to obtain good imaging in Cryo-SXT. In order to acquire high contrast image of live cells, it need to prepare the specimen ice as thin as possible. However, as the thickness of the ice layer is further reduced, the live cells may be destroyed during the tilt series data collection of 3D imaging due to radiation. Thus, it is essential to seek out a proper thickness range of the ice layer to get high contrast image without radiation damage of cells. For further understanding the relationship between thickness of ice layer and degree of radiation damage, yeast cells with different thickness of ice layer were imaged using Cryo-SXT. Finally the ice layer with thickness about 10 μm was confirmed to be proper for good imaging.
Collimators optimization for EDXRD security screening system
Author(s):
Tianyi YangDai;
Li Zhang
Show Abstract
Energy dispersive x-ray diffraction (EDXRD) is a promising technique in security screening. The study focuses on the collimators optimization to achieve the highest system sensitivity under certain spatial and angular resolution requirements. The effects of system parameters on the resolution have been studied using an efficient and simple simulation method. The angular resolution requirements play the major limiting role when the length of the collimator is small, while the spatial resolution limit the sensitivity and the angular resolution requirements are automatically satisfied with the increasing of the collimator’s length. Several other suggestions on the EDXRD system designs are also proposed.
Radiation temperature measurement of optical thick hypersonic combustion flow
Author(s):
Bin Qi;
Li-song Zhang;
Wei Dong;
Ning Tian;
Ling Zhao;
Yijie Pan;
Yun-long Zhao
Show Abstract
Temperature is a critical parameter to diagnose the high temperature hypersonic combustion flow. A fiber-spectrometer
based measurement system and the correlated theoretical models to measure the radiation temperature of the “optical
thick” hypersonic combustion flow were established in this paper. The spectral responsivity of the fiber-spectrometer
based measurement system was measured at NIM in lab condition, and the spectral radiance and emissivity of the
hypersonic combustion flow were measured in-situ at the combustion wind tunnel of BISLMV. Preliminary experimental
results showed the spectral emissivity of the combustion flow was about 0.1 in the spectral range 500-800nm without
strong spectral selection, which resulted in the radiation temperature about 2200 K, with relative standard uncertainty
about 10%.
Phosphorescent imaging technique on simultaneous measurements of spray flows in heated air
Author(s):
Fang Chen;
Hong Liu;
Haixing Li;
Hui Hu
Show Abstract
In the present study, phosphorescent imaging technique was developed to achieve simultaneous measurements of droplet size, speed and temperature of dispersed droplets in spray flow ejected from an air-blast nozzle. By using phosphorescent molecules as the tracers excited by an ultraviolet laser sheet for the quantitative flow measurements, the detected images of tagged phosphorescent molecules at two successive times determine the dynamic and thermodynamic behaviors of dispersed particles. A PTV based method was used to analyze the droplets size, trajectory and speed, and a lifetime based approach was used to measure the cross-correlated droplets temperature. The experimental results demonstrated phosphorescent imaging technique behaves the potential to widely used and well suited for spray measurement and droplet characterization.
A simplified mathematical model for the flame temperature field of illuminant based on burning particles
Author(s):
Chen-Guang Zhu;
Rui Xue;
Chang-Jin Lin;
Yan Li
Show Abstract
Illuminant is a porous media consisting of powder materials. The flame of illuminant seems
continuous, but in fact the flame is made up of a substantial number of burning particles, and the
burning particles determine the temperature distribution of the flame. In this paper, the distribution of
the burning particles was first studied using a high speed camera. Then a model of the temperature
field of illuminant flame was established based on the equation of heat conduction and the distribution
function of the burning particles. The temperature field of the illuminant flame was predicted by the
model and the highest temperature was measured using Fourier transform infrared spectrometer. The
model was validated by the experimental results using an infrared thermometer. The results indicate
that a good match has been achieved between the experimental data and the model predicted flame
temperature field of the illuminant based on the distribution of burning particles.
Diagnostics of ionization front and plasma within femtosecond laser interferometer
Author(s):
Jinhai Sun;
He Cai;
Shaohua Zhang;
Xutao Zhang
Show Abstract
Based on analyzing the condition of transmission through high density plasma and its ionization front, and the theory of detecting plasma with holographic interferometer, diagnostic experiments of ionization front and plasma ionized by high laser electric field has been reported in this paper. The Mach-Zehnder interferometer with the femosecond laser of center wavelength of 800nm and pulse duration of 58fs has been used to get interference images in CCD camera. By Abel inversion, the density map of plasma has been obtained based on the interference image. Evolution pictures of ionization front within the time or propagation distance have been reported and ionization front’s size has been estimated with the help of 4mm diameter of nozzle. One good diagnosis method for ionization front and plasma has been given within these experiments.
Classification extraction of land coverage in the Ejina Oasis by airborne hyperspectral remote sensing
Author(s):
Yang Su;
Yuan Qi;
Jianhua Wang;
Feinan Xu;
Jinlong Zhang
Show Abstract
The hyperspectral data of the Ejina Oasis is performed dimensionality reduction by the minimum noise fraction transform, classified by the maximum likelihood method and clustering processing and finally, the classification of land coverage is obtained. The thesis analyzes the results of two dimensionality reductions, and finds the superiority of the minimum noise fraction. In the classification of land coverage, the overall accuracy and Kappa coefficient are respectively 87.75% and 0.8401. The classification is of high precision and can provide effective parameters for ecological research.
Efficient artificial targets estimation via BING
Author(s):
Lin Wang;
Can Ding
Show Abstract
Objects with well-defined closed boundary can be discriminated by looking at the norm of gradients. With suitable resizing of their corresponding image windows into a small fixed size(8×8), and further binarized the normed gradients (BING) of images can describe the generic objectness measure. Inspired by the “BING” and considered the character that the artifical targets have many obvious corner points, in this paper we propose to predict candidate windows based on corner points instead of non-maximal suppression the BING used. We can generate a small set of high quality target windows and yield 96.2% object detection rate (DR) like the BING dose but need only half time. This is because of the number of corner point is much less than the number of non-maximal suppression point. Our method generate a small set of high quality target window.
Research about the effect of straw burning on aerosol in Northeast China based on MODIS
Author(s):
Mingchao Zhang;
Jingchao Li;
Hui Chen;
Lei Yao;
Hui Chen;
Wanjuan Liang
Show Abstract
Straw burning has great influence on ambient air quality. In this paper, we study the advantages of satellite remote sensing monitoring technology, extract the straw burning and aerosol remote sensing monitoring results from the MODIS data during Sep-Oct-Nov 2013 in Northeast China. We analyze the temporal and spatial distribution characteristics of straw burning and aerosol in autumn, and study through the statistics and relevant analysis method for the quantitative straw burning in northeast China's impact on local air quality. The results show that the monthly change of straw burning and AOD in the autumn of 2013 has a high consistency, from which in October the straw burning is the most frequent, aerosol pollution is also the most serious. And the straw burning point distribution density area and the AOD high value area are basically consistent with the space position. Furthermore, every increase of a straw burning point can make the monthly average AOD of the three provinces of northeast China increases by 0.0006.
Retrieving inherent optical properties for turbid inland waters: an improved quasi-analytical algorithm based on the linear spectral backscattering coefficient constraint
Author(s):
Feng Xie;
Changxing Zhang;
Honglan Shao;
Chengyu Liu;
Zhihui Liu;
Gui Yang;
Jianyu Wang;
Jianyuan Lin
Show Abstract
The inherent optical property is a significant bridge between the hyperspectral remote sensing data and water color and water quality parameters. Based on the water optical radiation transfer process and existing quasi-analytical algorithm (QAA), this study provides an improved algorithm, namely a linear spectral backscattering coefficient constraint quasianalytical algorithm (LSBCC-QAA), suitable for the retrieval of inherent optical properties for turbid inland waters to address the deficiency of the QAA on the retrieval of inherent optical properties for turbid inland waters. LSBCC-QAA uses the water-leaving reflectance of the bands between 1600 and 1700 nm to estimate the water surface reflectance of the bands between 400 and 900 nm and selects 700~850 nm as the reference wavelengths to estimate the water backscattering coefficients, taking full advantage of the continuity of the backscattering coefficient spectrum. The preliminary validated results show that the particle absorption coefficient, particle backscattering coefficient and phytoplankton absorption coefficient retrieved by LSBCC-QAA are more consistent with the actual situation than those retrieved by the common QAA_v6 algorithm or QAA-Turbid algorithm. Compared with the measured particle diffuse attenuation coefficient, the error of the LSBCC-QAA retrieved particle diffuse attenuation coefficient ranges from 16.0% to 22.9%, and the average error is 18.4%.
Self-calibration method for eccentric angle in hyperspectral and LiDAR integrated airborne system
Author(s):
Gui Yang;
Feng Xie;
Chengyu Liu;
Honglan Shao;
Jianyuan Lin;
Jianyu Wang;
Ying Guo
Show Abstract
Eccentric angle between IMU and the collimation axis of airborne sensor is one of main reasons causing geometric correction error. Currently, the application of the hyperspectral and LIDAR integrated system are greatly affected by lack of universal calibration methods which can calibrate the hyperspectral data and LiDAR data simultaneously. An eccentric angle calibration model for hyperspectral and LiDAR integrated system is proposed, meanwhile a self-calibration method using “#” shaped flight strip is designed to validate the new calibration model. Firstly, the homogeneous points are searched from all geometrically corrected flight strips by automatic matching methods. Secondly, control points obtained by averaging the coordinates of the homogeneous points are applied to solve the calibration model to get the eccentric angle. Finally, the point clouds are corrected geometrically with the solved eccentric angle, then the above steps are repeated until the solved eccentric angles are stable. An experiment was carried to testify the new calibration model and resolving method, which shows that the proposed model is of high-precision, validity and the resolving method is of fast convergence. The airborne sensors can acquire a plane precision of 0.807 m (about 1.2 pixels) without any ground control points, and the LiDAR can acquire a plane precision of 0.437 m and elevation precision of 0.15m.
Object contour reconstruction based on single camera and special geometry relation of mirror surfaces
Author(s):
Ye Yang;
Hongning Li;
Jinji Zheng
Show Abstract
We use four plane mirrors with their sides perpendicular to each other, use a single camera to take a shot, and by analyzing the mirror images in parallel mirrors, it can realize the contour collection of objects. In this paper, the imaging principle of single camera combined with single plane mirror and a pair of parallel plane mirrors is analyzed and compared, and the image center coordinate of pixel depth is eliminated, and multi-facet mirror are used to eliminate the error point. The experimental results show that the contour of the model can also be obtained without using the image center, and with less errors points on reconstructed surface.
Design of double wedge depolarizer for grating imaging spectrometer
Author(s):
Yangming Jin;
Weimin Shen
Show Abstract
In this paper, we study a compact double wedge depolarizer for grating imaging spectrometers. Based on introduction of its working principle, the general relationship between polarization sensitivity of an optical system and the structural parameters of depolarizer is established by means of Muller matrix and Stokes vector. Through numerical analysis it is pointed out that the depolarizer has the best depolarization performance with appropriate crystal thickness when the angle of the first wedge crystal optical axis is 45° respect to grating groove orientation and the two optical axis of the crystal is mutually orthogonal. Finally, an example, a depolarizer for grating imaging spectrometers is designed and its performance is evaluated.
Application of NIR spectrum on detection of pesticide residues
Author(s):
Jinxiang Liu;
Jiangtao Fan;
Chaowei Zhuang;
Qionghai Dai
Show Abstract
In recent years, the detection of pesticide residues is an important research field in China. Traditional methods which include biochemical methods and chromatography methods have high requirement for the experimental environment. Thus traditional methods cannot complete tasks in a short time. NIR spectrum represents physical features of matters and pesticide residues on fruit can change the NIR spectrum reflected by surface. It is feasible to make sure that if there is pesticide residues on fruit or not by analyzing the NIR spectrum reflected by surface. The method of spectrum analysis is easy to conduct and faster than traditional methods.
PC software performance research of aerial imaging spectrometer data acquisition based on USB3.0
Author(s):
Junze Huang;
Yueming Wang;
Daogang He;
Yanan Yu
Show Abstract
In order to solve the need for PC software of aerial imaging spectrometer USB3.0 high-speed large-capacity data acquisition system development. The project bases on MFC and DirectDraw technology by VS2010 development environment. The system can complete imaging spectrometer data acquisition , data storage and real-time imaging to monitor through the parsing of the spectral image data protocol. In addition, this paper also analyzes the factors that affect data acquisition bottleneck from computer architecture and software. The test results show that the PC acquisition platform can stabilize at 1.28 Gpbs data acquisition speed of some aerial imaging spectrometer requirements .It’s a new Light-weight and compact, low-cost and universal data acquisition approach for aerial imaging spectrometer.
Experimental research on thermal conductive fillers for CCD module in space borne optical remote sensor
Author(s):
Yi Zeng;
Xue-bing Han;
Dong-shang Yang;
Li-jia Gui;
Xiao-xiang Zhao;
Fu-qi Si
Show Abstract
A space-borne differential optical absorption spectrometer is a high precision aerospace optical remote sensor. It obtains the hyper-spectral，high spatial resolution radiation information by using the spectrometer with CCD（Charge Coupled Device）array detectors. Since a few CCDs are used as the key detector, the performance of the entire instrument is greatly affected by working condition of CCDs. The temperature of CCD modules has a great impact on the instrument measurement accuracy. It requires strict temperature control. The selection of the thermal conductive filler sticking CCD to the radiator is important in the CCD thermal design. Besides，due tothe complex and compact structure, it needs to take into account the anti-pollution of the optical system. Therefore, it puts forward high requirements on the selection of the conductive filler. In this paper, according to the structure characteristics of the CCD modules and the distribution of heat consumption, the thermal analysis tool I-DEAS/TMG is utilized to compute and simulate the temperature level of the CCD modules, while filling in thermal grease and thermal pad respectively. The temperature distribution of CCD heat dissipation in typical operating conditions is obtained. In addition, the heat balance test was carried out under the condition of two kinds of thermal conductive fillers. The thermal control of CCD was tested under various conditions, and the results were compared with the results of thermal analysis. The results show that there are some differences in thermal performance between the two kinds of thermal conductive fillers. Although they both can meet the thermal performance requirements of the instrument, either would be chosen taking account of other conditions and requirements such as anti-pollution and insulation. The content and results of this paper will be a good reference for the thermal design of the CCD in the aerospace optical payload.
The application of random phase filter in the image recognition
Author(s):
Xiujuan Yang;
Mei Zhong;
Zhufeng Shao
Show Abstract
We define one kind of new correlation, i.e. random phase correlation, which based on the Random Fourier Transform (RFT). An optical pattern recognition system, random phase filtering, is given according to random phase correlation. Furthermore its electro-optical setup is given for the application in image recognition. By the numerical simulation on computer, when the, we have found the proposed random phase filter can recognize the small change of object image and has higher recognition capability comparing of other three conventional correlators, the classical marched filter, the phase-only filter and the pure phase correlator.
Multi-spectral imaging system based on light field rendering
Author(s):
Chao Tang;
Jing Zhang;
Bin Gao;
Qionghai Dai
Show Abstract
Dynamic Acquisition of multi-spectral light field image with high resolution, is a conundrum in Computational Photography. In this paper, we propose a multispectral imaging system based on multi-view light field rendering. The hardware system architecture consists of equidistantly fixed camera array and various spectral filters, and we use an algorithm based on frequency domain pyramid decomposition to calculate the disparity at different view angles. So we can realize the cross-channel image matching so as to obtain the single- view image under the multi-spectral channel and achieve the high-resolution real-time multi-spectral imaging.
Mineral identification of hyperspectral images based on the stability of the spectral characteristic parameters
Author(s):
Yongfei Che;
Yingjun Zhao
Show Abstract
Spectral stability characteristic parameter analysis is the basis of all the quantitative information extraction in hyperspectral image. The results show that the stability of the spectral parameters used in the spectral identification has a great influence on the efficiency of mineral identification. A mineral recognition method for hyperspectral remote sensing image based on spectral stability characteristic parameter is introduced. First, reference spectrum spectral peaks and valleys positions were extracted, then calculates the measured spectra corresponding spectral wavelength and reference spectrum of each with a characteristic peak and valley of the correlation coefficient, basis of comparison of two spectral similarity to determine the matching effect of the two spectra, in order to achieve the best mineral identification precision and accuracy. Gansu Beishan Shijinpo gold mining area as an example, the mineral identification map was obtained. After field verification, it was confirmed that the method has higher accuracyon the mineral recognition.
Research on techniques for geometric calibration of three fields push-broom-type sensor
Author(s):
Qian Chen;
Yan-hua Ma;
Di Chen
Show Abstract
The paper combines with three fields push-broom-type sensor, which is independently developed by Shanghai Institute of Technical Physics, Chinese Academy of Sciences, and with the use of full color light source, reflected mirror, rotating table, parallel light tube, image acquisition software, computers and other laboratory equipment to create a geometric calibration method. The method aimed at three fields’ push-broom- type sensor imaging system, and we can get the geometric calibration raw data. The geometric calibration method can provide a method to establish an image mosaic model, and provide basic data for the geometric correction[1] about image distortion.
Hyperspectral feature mapping classification based on mathematical morphology
Author(s):
Chang Liu;
Junwei Li;
Guangping Wang;
Jingli Wu
Show Abstract
This paper proposed a hyperspectral feature mapping classification algorithm based on mathematical morphology. Without the priori information such as spectral library etc., the spectral and spatial information can be used to realize the hyperspectral feature mapping classification. The mathematical morphological erosion and dilation operations are performed respectively to extract endmembers. The spectral feature mapping algorithm is used to carry on hyperspectral image classification. The hyperspectral image collected by AVIRIS is applied to evaluate the proposed algorithm. The proposed algorithm is compared with minimum Euclidean distance mapping algorithm, minimum Mahalanobis distance mapping algorithm, SAM algorithm and binary encoding mapping algorithm. From the results of the experiments, it is illuminated that the proposed algorithm’s performance is better than that of the other algorithms under the same condition and has higher classification accuracy.
Electronic correction method for environment monitoring instrument
Author(s):
Quan Zhang;
Fuqi Si;
Shuhua Huang;
Xin Zhao;
Haijin Zhou;
Minjie Zhao;
Yu Wang;
Wenqing Liu
Show Abstract
The space-borne Environment Monitoring Instrument detects the Earth's surface radiation from ultraviolet to visible band, and it could be used to inverse the trace gas concentrations of target area. To obtain the 1b radiation data products, raw measurement data (level 0 data) should be corrected and modulated. Based on CCD detectors and payload’s characteristics, the electronic correction processing flow and data correction algorithm are proposed, and dark current, electronic offset, Smear and PRNU are also corrected. By using this algorithm, the ground level 0 test data are corrected. The result shows that the corrected data can improve the accuracy of the data; it can be used to process the data which are measured in orbit observation; it strongly guarantees the formation of further level 2 data products.
Hyperspectral image feature extraction method based on sparse constraint convolutional neural network
Author(s):
Peiyuan Jia;
Miao Zhang;
Wenbo Yu;
Yi Shen
Show Abstract
According to the characters of complex hyperspectral data, sparsity technique is introduced to deep convolutional neural network to handle feature extraction and classification problems. Combining sparse unsupervised learning method with neural network model, it is possible to get a good, sparse representation of the spectral information so that deep CNN model could extract feature information hierarchically and effectively. EPLS algorithm is applied in this paper to combine population sparsity and lifetime sparsity with the advantages of extracting deep feature information of CNN model to get a fine classification model. In the experiment, two hyperspectral data sets are applied for the proposed method, and the results demonstrate fine classification performances of the model.
New airborne wide-field hyperspectral imaging system using whiskbroom mode
Author(s):
Xuan Yang;
Hongxing Qi;
Min Xu;
Yikun Wang;
Yubo Liu;
Lei Wang
Show Abstract
To achieve airborne wide-field hyperspectral remote sensing, we often use a way of splice two or more detectors. This paper proposes a new whiskbroom hyperspectral imaging system with using a motion structure scanning to obtain a wide-field hyperspectral data. In the meantime, aircraft’s attitude disturbance could be compensated. Compared with field splicing, the system reduces complexity and cost of optical structure. We provide a new method to realize significant airborne wide-field, high-resolution remote sensing spectral imaging.
Application requirement analysis of high spectral and high spatial resolution satellite for environment remote sensing monitoring
Author(s):
S. H. Liu;
Y. P. Yang;
Z. H. Zhao;
Y. J. Yao;
X. J. Mao;
Y. T. Wu;
Y. H. Gao
Show Abstract
China's environmental situation is still grim, environmental pressure continues to increase. The demand of environmental protection work in the new era for high resolution remote sensing application will continue to increase. Environmental monitoring has multi factor, quantitative inversion and high precision as features, environment department need to use a wide spectrum of remote sensing data with high spectral resolution capability to monitor the total amount of pollutants in macro scale and long time series. The implementation of the high resolution earth observation project provides support for the improvement of the quantitative application of environmental remote sensing. On the basis of sorting out the key work of environmental protection, the application requirements of high spectral resolution and high spatial resolution satellite remote sensing in the field of environmental protection and the building needs of national environmental remote sensing application platform are put forward.
Research and application of high frame frequency CCD drive technology in hyperspectral spectrograph
Author(s):
Yanan Yu;
Shengwei Wang;
Ding Zhao;
Liyin Yuan;
Changxing Zhang;
Hongxuan Yu;
Yueming Wang
Show Abstract
As a key component of the hyperspectral imager, the use of high frame frequency CCD was more and more widely. CCD working principle was analyzed. Methods to realize high frame frequency and image programmable online were presented. Hardware driver design was designed. The image with high visibility, whose frame frequency was more than 320 Hz, noise was below 75e-, dynamic range was superior to 70dB, was acquired by the CCD. Based on the operating characteristic of the CCD, the temperature experiment was designed. Through the experiment, the relation curve of dark level and noise with the CCD detector temperature was given, which was helpful for the later image correction.
Bus current analysis of high power cryocooler's controller
Author(s):
Zhanlei Jin;
Qiyang Sun;
Liqun Dai;
Jie Dong
Show Abstract
Current analysis was an important research content for reducing power of cryocooler’s controller. Simulation was done among load current, H bridge current and power current refer to 42V bus power voltage. Then relationship among IL1, IC1, ρ and IM1 was established. Simulation results indicate that IL1-max, IL1-ave, IL1-rms, IC1-min and IC1-ave were linearly increasing to ρ and IM1, especially IL1-rms ≈ 0.612ρ IM1-max . IC1-rms increase firstly then decrease with the increasing of ρ. IC1-rms reaches maximum when ρ=0.8, then ICL-rms =(12.32/RM1 + 0.98) exp -((ρ-0.78)/0.57)2. The results were useful for miniaturizing cryocooler’s controller.
Comparative study on fluorescence spectra of Chinese medicine north and south isatis root granules
Author(s):
Lan Liang;
Qing He;
Zhenqiang Chen;
Siqi Zhu
Show Abstract
Since the spectral imaging technology emerged, it has gained a lot of application achievements in the military field,
precision agriculture and biomedical science. When the fluorescence spectrum imaging first applied to the detection of
the feature resource of Chinese herbal medicine, the characteristics of holistic and ambiguity made it a new approach to
the traditional Chinese medicine testing. In this paper, we applied this method to study the Chinese medicine north and
south isatis root granules by comparing their fluorescence spectra. Using cluster analysis, the results showed that the
north and south Banlangen can not be divided by ascription. And these indicate that there is a large difference in the
quality of Banlangen granules on the market, and fluorescence spectrum imaging method can be used in monitoring the
quality of radix isatidis granules.
TMS320C5402 is applied in the system of data fusion
Author(s):
Yuan Yao
Show Abstract
TMS320C54X series DSP which TI Company produces has applied in communication domain,The series has many
merits,such as low power consumption and high parallel,which satisfied the request of real-time processing in
communication domain. This paper has mainly explained a kind of design scheme for data fusion system based on
TMS320C5402, and briefly given a design method of making use of UART(Universal Asynchronous Receiver
Transmitter) TL16C654 and FPGA to implement the communication with other terminal devices. Both C language and
assembly language are adopted to carry out software design, which makes program much transplantable. The results
demonstrate that the system runs steadily and realtime communication among subsystems have been accomplished
perfectly.
An INS data based approach to star image simulation for ship-borne star sensor
Author(s):
Cong Sun;
Hai-bo Liu;
Xiao-hu Zhang;
Qi-feng Yu
Show Abstract
The technique of the star image simulation is widely used to test star identification algorithms and the performance of
star sensor on the ground. A novel INS data based approach to ship-borne star map simulation is put forward in this
paper. The simulation procedure consists of three steps: Firstly, the exact speed and position of the ship in the
Conventional Inertial System(CIS) are calculated via the INS data; and then the ship attitude matrix is obtained.
Secondly, considering the azimuth angle and elevation angle of the star sensor, the accurate positions of the selected
guide stars on the image plane of the star sensor are derived by constructing a pinhole model. At the third, the gray
values of simulating star image pixels are evaluated according to the 2D Gaussian distribution law. In order to simulate
the star image precisely and actually, the image smear has been considered. Based on the proposed star image simulation
approach, the effects of image smear on star sensor recognition capability have been analyzed in different exposure time.
Study on spatial modulating spectropolarimetry with double combo wedge modulator
Author(s):
Shuang Li;
Ping Gong;
Qiyue Han;
Qi Yuan;
Lin Han
Show Abstract
We present an approach to spectropolarimetry with no moving parts. The approach encode the
polarization information at each wavelength along the spatial dimension of a two dimension date array using
static, robust double combo wedges modulator, and realize the measurement of full Stokes parameters. Firstly,
the paper present the principle of spatial modulating spectrometry and its configuration; Secondly, the
measurement matrix is derivate at different configuration of double combo wedges; Finally, measurement error
distribution of Stokes parameters in different measurement matrix is calculated using least squares method, and
the analyzer angle of polarizer is given with the minimum variance for each Stokes parameters.
Detection of NH3 using logarithmic-transformed wavelength modulation spectroscopy
Author(s):
Menglong Cong;
Dandan Sun;
Shanshan Zhang
Show Abstract
Conventional wavelength modulation spectroscopy is improved by logarithmic-transformed data
processing for trace gas sensing. Via the logarithmic-transformation, the optic intensity modulation is
isolated from the gas absorption induced laser power attenuation, and then the optic intensity modulation is
offset by its equivalent which is obtained from a referenced beam. The method is validated by the detection
of P(6) NH3-absorption line in a stainless tube with effective path length of 24.5 cm, under room
temperature (296 K) and atmospheric pressure (1.01e5 Pa). The second harmonic is recovered while the
residual amplitude modulation and distortion of curve are eliminated. A 0.7 ppm (part per million)
detection limit is inferred on the assumption that the signal is equal with the noise.
Multi scale sequential median filter for high percentage impulsive noise removal
Author(s):
Dongjie Tan;
Haoyin Lv
Show Abstract
Impulsive noise usually has adverse effect on image processing. It has been proved that adaptive median filter is
effective to impulsive noise removal. However, high percentage impulsive noise is still a challenge to adaptive median
filter. Thus, a sequential median filter is proposed in this paper. Adaptive median filter and median filter are combined in
sequence to handle high percentage impulsive noise. Moreover, variable window sizes are employed in the sequential
median filter. Experimental results indicate that the sequential median filter is effective for high percentage impulsive
noise removal.
Theory and experiment analysis of fiber Bragg grating external cavity lasers
Author(s):
Huijun Bai;
Yuefeng Wang;
Tianhua Guo
Show Abstract
The cavity theory model was proposed to discuss the wavelength tuning. The coupling efficiency between semiconductor
gain chip and FBG has great influence on the output characteristics. The mode coupling theory and ZEMAX numerical
simulation software are used to get the coupling efficiency curves, which are changed with alignment errors. The results
show that the conical lensed fiber’s coupling efficiency is highest, and adjustment tolerance is largest. We also
completed the experiment of center wavelength tuning and beam quality.
Using two different targets for the calibration of S-NPP VIIRS day night band under lunar illumination
Author(s):
Shensen Hu;
Shuo Ma;
Wei Yan;
Yunxian Huang
Show Abstract
The Day Night Band (DNB), mounted on the Visible Infrared Imaging Radiometer Suite (VIIRS) on board the
Suomi National Polar-orbiting Partnership (NPP), has the unique ability to image cloud and surface features with
reflected moonlight and nonlunar nighttime illumination sources. However, the radiometric calibration is too
difficult to be calculated directly at night due to extremely low radiance. The Dome C in Antarctic and Railroad
Valley Playa in Nevada are utilized to calibrate the DNB High Gain Stage (HGS) at night due to their invariable
surface properties. The mean value of the relative errors based on Dome C site is -7.41% and RVP is -4.14%. The
results suggest that there is an average bias in the DNB HGS on-orbit calibration and an unobvious trend exists due
to the changing relative spectral responses over time.
The development and application of high energy laser protective material
Author(s):
Xinying Zhao;
Yihua Hu;
Yizheng Zhao
Show Abstract
With the emergence of strong light source, laser weapons in the modern war, the threat of damage to the photoelectric sensor and the human eye, the laser protection technology has begun to be paid attention to and widespread concern. In the laser protective materials, we can divide it into the protective material based on the principle of linear optics and the protective material based on the principle of nonlinear optics. In this paper, two different mechanisms of laser protective materials are introduced, and their development and application are reviewed.
The preparation and application of the nonlinear optical quantum dots
Author(s):
Guochang Huang;
Dabin Yu;
Jinhua Zhang;
Minghui Zhao;
Dapeng Zhao;
Maosen Pan
Show Abstract
Quantum dots (QDs) is a new material with special photoelectric properties, whose optical nonlinearity is potentially and widely applied in laser protection and photoelectric devices. This thesis concludes the research progresses on quantum dots’s composition and superficial decoration means in organic polymer system and its linear and nonlinear effects and introduces the researches on the application of quantum dots.
A model-based denoising adaptive diffusion method based on multi-scale bilateral filter
Author(s):
Yu Hui;
Jun-Sheng Wu;
Bin Yu;
Chen Zhang
Show Abstract
In order to filter out the noise points of the medical spine model effectively
and keep the details of the model better, a model-based denoising adaptive diffusion
method based on multi-scale bilateral filter is proposed. This method firstly extracts
the contour lines of the 3D model of the spine by using bilateral filter in multi-scale
conditions, and then designs and improves the adaptive diffusion coefficient so as to
optimize and control the whole diffusion process. Then, according to the discreteness
of the image, the corresponding discrete iterative equations are established to
discretize the iterative process, and the iteration stopping criterion is designed to make
the denoising and smoothing image model stop the iteration when the correlation
between that image model and the noise is the minimum, and finally to establish the
spine image denoising model. After compared with the experimental results of the
classical PM method, Catte method and other methods, this method achieves good
filtering effect in denoising, and also preserves the edge detail features of medical
image, much better than traditional filtering algorithm.
Dynamic transmittance of laser in the active microorganism
Author(s):
Baokun Huang;
Yihua Hu;
Yizheng Zhao;
Le Li;
Xinying Zhao
Show Abstract
A multilayer structure of microbial cells can result in the multiple attenuation of electromagnetic waves, making the
biological particles have a strong ability of extinction. And the activity of microorganism is also an important factor that
affects the change of laser transmittance. In this paper, the dynamic change of the transmittance of 632.8nm laser in
biological materials is measured. The results show that: when the biological material is stimulated by the laser, the stress
response occurs, and the movement of escaping light is the main factor of causing the change of the transmittance. This
provides a reference for the further development of the biological extinction materials.
Analysis of link adaptive method for data transmission of remote sensing satellite
Author(s):
Pengyun Wang;
Yurong Liao;
Dan Ding;
Shuyan Ni
Show Abstract
To satisfy requirements of remote sensing satellite data transmission . Considering link margin is not fully
utilized by fixed rate methods , development research on link adaptive transmission for remote sensing satellite to
improve efficiency of link resources using . Simulation and calculation results show the data throughtput of link
adaptation is 2.62 times than conventional method.
Mass sensor based on split-nanobeam optomechanical oscillator
Author(s):
Yeping Zhang;
Jie Ai;
Yanjun Xiang;
Qinghua He;
Tao Li;
Jingfang Ma
Show Abstract
Mass sensing based on monitoring the frequency shifts induced by added mass in oscillators is a well-known and widely
used technique. The optomechanical crystal cavity has strong interaction between optical mode and mechanical mode.
Radiation pressure driven optomechanical crystal cavity are excellent candidates for mass detection due to their
simplicity, sensitivity and all optical operation. In an optomechanical crystal cavity, a high quality factor optical mode
simultaneously serves as an efficient actuator and a sensitive probe for precise monitoring the mechanical frequency
change of the cavity structure. Here, a split-nanobeam optomechanical crystal cavity is proposed, the sensing resolution
as small as 0.33ag (1ag=10-21kg) and the frequency shift is more than 30MHz. This is important and promising for
achieve ultimate-precision mass sensing including proteins and other molecules.
Infrared and visible image fusion with the target marked based on multi-resolution visual attention mechanisms
Author(s):
Yadong Huang;
Kun Gao;
Chen Gong;
Lu Han;
Yue Guo
Show Abstract
During traditional multi-resolution infrared and visible image fusion processing, the low contrast ratio target may be weakened and become inconspicuous because of the opposite DN values in the source images. So a novel target pseudo-color enhanced image fusion algorithm based on the modified attention model and fast discrete curvelet transformation is proposed. The interesting target regions are extracted from source images by introducing the motion features gained from the modified attention model, and source images are performed the gray fusion via the rules based on physical characteristics of sensors in curvelet domain. The final fusion image is obtained by mapping extracted targets into the gray result with the proper pseudo-color instead. The experiments show that the algorithm can highlight dim targets effectively and improve SNR of fusion image.
Performance of backscatter visibility lidar at UYN airport
Author(s):
Hongda Tai;
Xiaohua Kang;
Zibo Zhuang;
Dongsong Sun
Show Abstract
Backscatter visibility lidar has been installed at Yuyang (UYN) airport for precise measurements of visibility. The present study conducted the first experiments to compare visibility results of different measurement instruments involving backscatter visibility lidar. The present study introduced the system structure of the backscatter visibility lidar, and then compared the visibility data under different weather conditions viz., haze-fog, snow, dust and rain. The results of the backscatter visibility lidar are superior to the forward scatter meter in all kinds of weather conditions. The measurement results of the backscatter type visibility meter had little deviation from the transmissometer and the manual visual measurement under haze-fog weather. Under the rain and dust weather conditions, the deviation of the results measured by backscatter visibility lidar were larger than transmissometer and the manual observed, but the deviation was still less than the forward scatter visibility meter. The result should be confirmed by more experiments under different weather conditions.
Verification experiment of electron shunt for complex waveguide grid micro-channel plate-photomultiplier tube
Author(s):
Xu Gao;
Yi-Ning Mu;
Ye Li;
Yue Du;
MeiTing Wang
Show Abstract
With further research on the micro channel-plate(MCP) photoelectric multiple structure of anodized transmission of composite waveguide applied in Free-Space Optical communication, the disadvantage of the models have been found. Firstly, some analyzes about the constraint conditions and performance of the MCP photoelectric multiple structure of composite waveguide have been conducted. Secondly, one device model based on one grid-controlled structure of composite waveguide has been introduced and verifiable experiments have been conducted as a support. Then, the capability of electron transport of two structures is compared by theoretical analyzes. Lastly, the difference between performances of these two structures has been confirmed by verifiable experiments with optical axis positioning by four-quadrant in a vacuum. Results of the experiment have showed that the grid-controlled structure of composite waveguide would be likely to be widely applied in the special detection for its advantages in the future.
Spectral radiance measurement of hypersonic combustion flow based on fiber spectrometer
Author(s):
Bin Qi;
Li-song Zhang;
Kai Zhang;
Ling Zhao;
Wei Dong;
Yijie Pan;
Yun-long Zhao
Show Abstract
A high speed, high resolution spectrum measurement system based on fiber-spectrometer was built to diagnose the high
temperature hypersonic combustion flow. The theoretical models of the spectral radiance and transmittance of the
hypersonic combustion flow were established in this paper. The spectral radiance and transmittance of the hypersonic
combustion flow were measured at the combustion wind tunnel of BISLMV. Preliminary experiments showed that the
spectral radiance behaved not like typical gas radiation but have a continuous spectrum, and the spectral transmittance of
the combustion gas flow was about 0.9 in the spectral range 500-900nm without strong spectral selection. The results
obtained in this paper will benefit the surface temperature measurement of the thermal protection materials of space
vehicle tested at BISLMV.
An infrared small target detection method based on visual spatio-temporal local contrast measure
Author(s):
Longguang Wang;
Zaiping Li;
Xinpu Deng
Show Abstract
Human visual system (HVS) can detect the target utilizing the contrast of the target and the surrounding background
under a low SNR, it is not only sensitive to the local contrast in space domain, but also in time domain. The existing
infrared small target detection methods based on HVS are mainly based on the local contrast in space domain, while the
false alarm caused by the background clutter could be serious. In consideration of this problem, an infrared small target
detection method based on visual spatio-temporal contrast measure (STLCM) is proposed. At the first stage, a temporal
local contrast measure (TLCM) was presented. At the second stage, visual spatio-temporal contrast measure was derived
by the fusion of the local contrast in time and space domain, then an adaptive threshold was adopted in the saliency map
of STLCM to segment the target. Experimental results demonstrate that the proposed method is superior in compressing
the false alarm and efficient in different conditions.
Statistical learning modeling method for space debris photometric measurement
Author(s):
Wenjing Sun;
Jinqiu Sun;
Yanning Zhang;
Haisen Li
Show Abstract
Photometric measurement is an important way to identify the space debris, but the present methods of photometric
measurement have many constraints on star image and need complex image processing. Aiming at the problems, a
statistical learning modeling method for space debris photometric measurement is proposed based on the global
consistency of the star image, and the statistical information of star images is used to eliminate the measurement noises.
First, the known stars on the star image are divided into training stars and testing stars. Then, the training stars are
selected as the least squares fitting parameters to construct the photometric measurement model, and the testing stars are
used to calculate the measurement accuracy of the photometric measurement model. Experimental results show that, the
accuracy of the proposed photometric measurement model is about 0.1 magnitudes.
Study on cathode high voltage pulse control in image intensifier
Author(s):
Ye Yang;
Bo Yan;
Xiao-bing Ni;
Qiang Zhi;
Jun-guo Li;
Ze Yao;
Guang-xu Deng
Show Abstract
This paper briefly introduces the basic working principle of auto-gating power source. Due to the presence of noise in the
circuit, the cathode pulse signal generated by the AD converter is unstable. In this paper, the circuit of the AD converter
is adjusted to improve the instability of the cathode high voltage pulse signal, especially in the case of low light and high
illumination to avoid the jitter of the pulse. The experiment was carried out. And it could guide the implementation of
this part of the circuit.
Infrared small target detection method based on local threshold attenuation of constant false alarm
Author(s):
Ke-feng Yu;
Zhi-guang Shi;
Xin-ping Lu
Show Abstract
In the infrared small target detection system, CFAR (Constant False Alarm Rate) is a commonly used technology, but in the traditional single frame detection method, detection rate is requested to be improved while the false alarm rate is increasing. This paper proposes a threshold attenuation CFAR detection method based on Gauss distribution. After the preprocessing of infrared images, we came into the designing of CFAR detector based on Gauss distribution. According to the previous frame target location and attenuation of local threshold, the detection rate of the target neighbourhood can be improved to obtain the current target location. The experimental results show that the proposed method can effectively control the threshold, and under the precondition that the background clutter was suppressed by the global low false alarm rate, it can improve the local detection rate and reduce the probability of target loss.
Patterned sub-wavelength structure on vanadium oxide film enhancing dual-band absorption
Author(s):
Qi Li;
Bingqiang Yu;
Haiou Li;
Zhaofeng Li;
Xiaofeng Wang;
Lingfeng Pan
Show Abstract
We propose a sub-wavelength structure on vanadium oxide film as an extra
absorption layer (i.e. absorber) based on surface plasmon resonance effects, enhancing
dual-band absorption in both middle wavelength infrared (MWIR) and long wavelength
infrared (LWIR) region. Simulation results show that the absorber with disk structure has two
absorption peaks at wavelengths λ=4.8μm and λ=9μm with the absorption magnitudes more
than 0.98 and 0.94 in MWIR and LWIR region, respectively. Similarly, simulation results
show that the absorber with square structure has two absorption peaks at wavelengths
λ=4.8μm and λ=9.2μm with the absorption magnitudes more than 0.99 and 0.99 in MWIR
and LWIR region, respectively.
Image restoration for large-motion blurred lunar remote sensing image
Author(s):
Zhihai Xu;
Pengzhao Ye;
Guangmang Cui;
Huajun Feng;
Qi Li;
Yueting Chen
Show Abstract
In the field of deep space science detection and high resolution earth observation, a relatively high motion velocity is often generated between the optical camera and the imaging target. Images obtained during the exposure time can produce image motion blur, which becomes one of the main obstacles to acquire high resolution image near the target. As an extended task of the third phase of China’s lunar exploration program, flight imaging of the planned sampling area of Chang’e-5 was carried out. A dual resolution camera with a wide field of view (FOV) camera and a narrow FOV camera was used for imaging mission. High flying speed causes the generation of large motion blurred images captured by the narrow FOV camera and the motion blur can be up to around 30 pixels. To deal with this problem, we analyzed the image features of the blurred images captured by the narrow FOV camera, and proposed a corresponding method that can estimate image motion value from the blurred lunar image based on small craters detection scheme and then adopted the regularization method to restore the image. The algorithm is applied in the batch processing of the real blurred lunar images and has achieved a significant restored effect.
Modulation transfer function (MTF) measurement method based on support vector machine (SVM)
Author(s):
Zheng Zhang;
Yueting Chen;
Huajun Feng;
Zhihai Xu;
Qi Li
Show Abstract
An imaging system’s spatial quality can be expressed by the system’s modulation spread function (MTF) as a function of
spatial frequency in terms of the linear response theory. Methods have been proposed to assess the MTF of an imaging
system using point, slit or edge techniques. The edge method is widely used for the low requirement of targets. However,
the traditional edge methods are limited by the edge angle. Besides, image noise will impair the measurement accuracy,
making the measurement result unstable. In this paper, a novel measurement method based on the support vector
machine (SVM) is proposed. Image patches with different edge angles and MTF levels are generated as the training set.
Parameters related with MTF and image structure are extracted from the edge images. Trained with image parameters
and the corresponding MTF, the SVM classifier can assess the MTF of any edge image. The result shows that the
proposed method has an excellent performance on measuring accuracy and stability.
The growth characters of InSb/GaSb quantum dots by LP-MOCVD
Author(s):
Shengtao Yu;
Xiaohuan Lu;
Bin Zhang;
Cui Xiong;
Chen Cai;
Liankai Wang
Show Abstract
InSb quantum dots of high quality and high density is grown epitaxially by LP-MOCVD technology on GaSb substrate, and some parameters influenced surface pattern of InSb is analyzed such as source flow, phase V/III ratio, growth temperature, pressure in reaction chamber, etc. Experiment obtained a set of optimized parameters of InSb/GaSb quantum dots: 475℃, 200mbar, V/III=1. Under optimized epitaxial parameters, using atomic-like layer growth pattern and connecting In and Sb organic source for four times alternatively can prepare InSb/GaSb quantum dots whose density can be up to 1.69×1010cm-2.
An auto tracking system of airborne single photon ranging
Author(s):
Yu Chen;
Yi Yang
Show Abstract
The transmit power and laser divergence angle of single photon laser ranging system for
airborne is a key factor restricting the measurement range. A method is proposed in this paper to reduce the
laser divergence angle to increase the measurement process. And an auto tracking system based on fast
steering mirror is proposed to improve the accuracy of the pointing error because of the small divergence
angle in airborne environment. On the theory, it can increase the measurement range of not increasing the
transmit power.
Research on degree of freedom of multi-configuration of the hexapod mounts based on the screw theory
Author(s):
Mingxin An;
Shuyan Xu;
Jihong Dong;
Lihao Zhang
Show Abstract
A new method for the determination of the degree of freedom of the hexapod mount based on screw theory has been
proposed. The method is applied to the mobility analysis of the four configurations of the hexapod mount, say the 3-3
configuration, 3-6 configuration, 6-3 configuration and 6-6 configuration. The conclusion which the DOF of the four
structures of the hexapod mount is zero and over-constraint does not exist has been derived by the analysis of the motion
screw systems of the four structures, and it also presents that the four structures are equivalent in DOFs and the DOF of
variation configuration of the hexapod mount is also zero and over-constraint does not exist, which provides a strong
theoretical support for the feasibility of the kinematic supporting of the optical module. The method also provides a reference
for the mobility analysis of other parallel manipulators.
Measuring raindrops using a precipitation micro-physical characteristics sensor
Author(s):
Xichuan Liu;
Yuntao Hu;
Taichang Gao;
Xiaojian Shu
Show Abstract
Aiming at the simultaneous measurement of the size, shape, fall velocity of precipitation particles, a ground-based
optical instrument, the precipitation micro-physical characteristics sensor (PMCS) was developed, it can record the
double-exposure image of each particle in a single frame, by which the size, equivalent diameter, axis ratio of raindrops
can be calculated, its fall velocity can be calculated according to its displacement and time interval. The PMCS is
calibrated by some glass balls with certain diameters in sunny, cloudy, and night conditions, based on which a fitted
relationship between the threshold and image area is obtained and used to ensure the measurement accuracy of raindrop
sizes. The field measurement of PMCS has obtained plenty of raindrops images, based on which the shape, axis ratio,
and fall velocity of raindrops were calculated and discussed. The typical shape of large raindrop takes on an oblate
ellipsoid with a flatter base and a more raised top, the axis ratio of raindrops decrease linearly with the increasing of
diameter, the fall velocity of raindrops increases exponentially with the increasing of the diameter, and above observed
data are in good agreement with the empirical model. These results validate the performance of PMCS, which can be
widely applied for interpreting weather radar data, investigating regional precipitation features, and studying the physical
process of precipitation.
Fast quantitative detection of thiram using surface-enhanced Raman scattering and support vector machine regression
Author(s):
Shizhuang Weng;
Baohong Yuan;
Zede Zhu;
Linsheng Huang;
Dongyan Zhang;
Ling Zheng
Show Abstract
As a novel and ultrasensitive detection technology that had advantages of fingerprint effect, high speed and
low cost, surface-enhanced Raman scattering (SERS) was used to develop the regression models for the fast quantitative
detection of thiram by support vector machine regression (SVR) in the paper. Meanwhile, three parameter optimization
methods, which were grid search (GS), genetic algorithm (GA) and particle swarm optimization (PSO), were employed
to optimize the internal parameters of SVR. Furthermore, the influence of the spectral number, spectral wavenumber
range and principal component analysis (PCA) on the quantitative detection was also discussed. Firstly, the experiments
demonstrate the proposed method can realize the fast and quantitative detection of thiram, and the best result is obtained
by GS-SVR with the spectra of the range of characteristic peak which are processed by PCA. And the effect of GS, GA,
PSO on the parameter optimization is similar, but the analysis time has a great difference in which GS is the fastest.
Considering the analysis accuracy and time simultaneously, the spectral number of samples over each concentration
should be set to 50. Then, developing the quantitative model with the spectra of range of characteristic peak can reduce
analysis time on the promise of ensuring the detection accuracy. Additionally, PCA can further reduce the detection error
through reserving the main information of the spectra data and eliminating the noise.
The optimization design and robust test of TVF for moving target detection
Author(s):
Jinyan Gao;
Zaiping Lin;
Wei An;
Longguang Wang;
Zhiheng Fu;
Jiahui Wang
Show Abstract
In order to detect the dim small target in high frame rate image sequences，an optimized temporal processing technique is
investigated. Based on the temporal profile models for noise pixel，target pixel and clutter pixel, we formulate the
detection in two steps, pre-processed by Max-median filter and temporal variance filter(TVF). In pre-processing step,
three spatial-filtering methods are compared. In temporal profile analysis step, the length of time windows for calculating
the mean and variance values are chosen after statistical analysis. Finally, six targets embedded into a scene which
contains different types of clouds, and set the adjacent scene to one pixel jitter in any random direction. The simulation
results show that we can obtain a relative high signal-to-clutter gain in different regions, which satisfies the requirement
of target detection algorithm in high frame rate detection system.
Research on the beam spot size measurement of terahertz laser
Author(s):
YanZhao Yang;
Bin Jiang;
Chengping Ying;
Kunfeng Chen;
Bin Wu;
HengFei Wang
Show Abstract
Terahertz technology is getting fast development in scientific research and the characteristics of terahertz beam is of great importance when using a terahertz laser. In this paper we scan the THz beam along its diameter by a slit and a circular aperture to measure the THz beam’s power distribution and thus get its spot’s size. The results show that the beam spot of the THz source we employed is satisfied with Gaussian distribution. The value of the peak power would affect the determination of the spot boundary, the influence of environmental noise will increases when the the peak power become weak and the measured spot diameter will be too large ultimately.
UV focal plane array device relative spectral response measurement technology research
Author(s):
HongYuan Liu;
ChengPing Ying;
Hongchao Wang;
Hengfei Wang;
Xueshun Shi;
Bin Wu;
Bin Jiang
Show Abstract
Spectral response is one of the important technological parameters of the detector, along with the development of the ultraviolet detector technology, accurate measurement of UV detector spectral responsivity is becoming more and more important. This paper analyzes the ultraviolet focal plane array relative spectral responsivity measurement principle, using the substitution method of measuring ultraviolet focal plane array detector relative spectral responsivity, and established a calibration device for relative spectral response of UV focal plane array. The relative spectral response of UV focal plane array device was obtained,can be seen from the curves, UV focal plane array device from 250 nm to 290 nm spectral response range, the peak response near 270 nm, Show that the array sun-blind characteristic of a device. The uncertainty of analysis results showed that UV focal plane array device relative spectral response measurement uncertainty of calibration device is about 3.6%, can meet the demand of high precision measurement.
Video motion magnification based on Laplacian-Riesz pyramid
Author(s):
Yi Liu;
Bindang Xue
Show Abstract
We propose a faster method for video motion magnification, which can make imperceptible motion visible for human eyes. Motion-magnified videos produced by our framework are of comparable quality to those produced with Riesz pyramid, but our method has higher computational efficiency. We use median filter to eliminate the grid noises at motion area edges. Experiments show our method is effective and efficient.
High-space-frequency correction method for infrared stripe nonuniformity
Author(s):
Junqi Bai;
Chencheng Yang;
Chunguang Zhao
Show Abstract
Infrared image quality is a key factor of object detection. Stripe nonuniformity is very typical in the staring infrared focal plane array (IRFPA). In this paper, we propose a novel high-space-frequency correction method to eliminate the stripe nonuniformity. The kernel ideal is to eliminate the high-space-frequency part of stripe nonuniformity and retain its low-space-frequency part which can reduce unwanted ghosting artifacts. Firstly, the spatial characteristic of stripe nonuniformity is discussed, then correction parameters are computed based on the spatial high frequency part of image. Experimental results show the proposed mehtod can compute adaptive correction parameters of each readout channel and obtain a reliable stripe nonuniformity reduction.
Radar cross section measurement of double S-shaped nozzle with radar absorbing material
Author(s):
Xiao Guo;
Qingzhen Yang;
Huichen Yang;
Kai Du
Show Abstract
The backward scattering characteristic of the jet engine nozzle is one of the most challenging problem in applied electromagnetics. Radar cross section (RCS) data of a double S-shaped nozzle (DSN) with and without radar absorbing material (RAM) were measured in the microwave chamber using stepping test system. The experiment results show that S-shaped structure has a certain effect on the backwards scattering characteristics. Coating RAM can reduce the RCS of DSN effectively.
Investigation of polarization matching based on dual-balanced coherent detection
Author(s):
Hua Zhang;
Yi-hua Hu
Show Abstract
The theoretical model and mathematical description of dual-balanced coherent detection ( or dual-balanced coherent detection ) are established，with which the current formula and output power formula of intermediate frequency (IF) signals are deduced. Theoretical analysis shows that this dual-balanced coherent detection technique can effectively solve the polarization matching of signal light and local light, and improve the stability of signal measurement, and reduce the influence on signal-to-noise ratio (SNR) of the system. Meanwhile, the technique also have the above advantages compared with single-balanced coherent detection. Hopefully, the dual-balanced coherent detection method could be applied in a wide range of fields.
Study and application of new Raman spectroscopy
Author(s):
Qiushi Liu;
Xiaohua Zhang
Show Abstract
Spatially Offset Raman Spectroscopy (SORS) is a new type of Raman Spectroscopy technology, which can detect the medium concealed in the opaque or sub-transparent material fast and nondestructively. The article summarized Spatially Offset Raman Spectroscopy`s international and domestic study and application progress on contraband detecting, medical science (bone ingredient, cancer diagnose etc.), agricultural products, historical relic identification etc. and stated the technology would become an effective measurement which had wide application prospect.
Application of signal processing based on mathematical morphology
Author(s):
Jian Chen;
Hong Chen;
Xiaoxia Cai;
Pengfei Weng;
Hao Nie
Show Abstract
With the development of mathematical morphology theory, the application of mathematical morphology in image processing has been very extensive, in recent years, with in-depth study of mathematical morphology and its applications in signal processing development is receiving more and more attention. As a kind of nonlinear signal processing method, its signal feature extraction is performed in time domain, compared with some other nonlinear and non-stationary signal processing method, which has no phase offset and amplitude attenuation etc. many advantages, so this method is applied to the signal processing in various industries. This paper mainly expounds the basic theory of mathematical morphology, and puts forward the method of mathematical morphology denoising pretreatment. Finally, the paper summarizes the application of mathematical morphology in speech signal processing and the combination of neural network.
Quantum secure direct communication scheme based on d- dimensional Bell entangled state
Author(s):
Pengfei Weng;
Hong Chen;
Xiaoxia Cai;
Jian Chen;
Hao Nie
Show Abstract
In order to improve the communication efficiency and security of Quantum Secure Direct Communication, a new Quantum Secure Direct Communication scheme based on d-dimension Bell entangled state is proposed. In the scheme, the receiver and the sender transport the d-dimensional Bell particles as secure test particles to ensure the security of communication. The receiver can calculate the security of the channel according to the measurement of d-dimensional Bell state particles, which is based on the entanglement properties of the d-dimensional Bell state. Secret information is transmitted through the other d-dimensional Bell state particles by dense coding technique. Then, the receiver can determine the security of the channel by comparing the measurements of the particles and makes a joint measurement of the transmitted particles to obtain secret information. Finally, the entropy theory is used to analyze the security of the protocol. Under the four dimensional Bell state, the transmission efficiency of the protocol is 90.90% and the efficiency of the quantum bit is 45.45%. The results show that the proposed scheme is safe and reliable and has high transmission efficiency.
Fusion of multi-spectral and panchromatic images based on 2D-PWVD and SSIM
Author(s):
Dongjie Tan;
Yi Liu;
Ruonan Hou;
Bindang Xue
Show Abstract
A combined method using 2D pseudo Wigner-Ville distribution (2D-PWVD) and structural similarity(SSIM) index is proposed for fusion of low resolution multi-spectral (MS) image and high resolution panchromatic (PAN) image. First, the intensity component of multi-spectral image is extracted with generalized IHS transform. Then, the spectrum diagrams of the intensity components of multi-spectral image and panchromatic image are obtained with 2D-PWVD. Different fusion rules are designed for different frequency information of the spectrum diagrams. SSIM index is used to evaluate the high frequency information of the spectrum diagrams for assigning the weights in the fusion processing adaptively. After the new spectrum diagram is achieved according to the fusion rule, the final fusion image can be obtained by inverse 2D-PWVD and inverse GIHS transform. Experimental results show that, the proposed method can obtain high quality fusion images.
Refractive index inversion based on Mueller matrix method
Author(s):
Huaxi Fan;
Wenyuan Wu;
Yanhua Huang;
Zhaozhao Li
Show Abstract
Based on Stokes vector and Jones vector, the correlation between Mueller matrix elements and refractive index was studied with the result simplified, and through Mueller matrix way, the expression of refractive index inversion was deduced. The Mueller matrix elements, under different incident angle, are simulated through the expression of specular reflection so as to analyze the influence of the angle of incidence and refractive index on it, which is verified through the measure of the Mueller matrix elements of polished metal surface. Research shows that, under the condition of specular reflection, the result of Mueller matrix inversion is consistent with the experiment and can be used as an index of refraction of inversion method, and it provides a new way for target detection and recognition technology.
High birefringence and near-zero dispersion photonic crystal fiber at the wavelength of 1.55 um
Author(s):
Peng Song;
Limin Wu;
Jing Wang;
Cheng Zhou
Show Abstract
We investigate a photonic crystal fiber (PCF) which consists of squeezed triangle lattice and elliptical air holes. Birefringence and dispersion properties of this PCF have been numerically estimated by the supercell lattice method. Numerical results show that the birefringence is on the order of 10-2 over ultrabroad wavelength rang from1.3μm to 1.7μm and birefringence can be reached 1.71×10-2 at the operating wavelength of 1.55μm. It is also demonstrated that two near-zero dispersion of -1.75(ps/nm/km) (x-polarized mode) and-0.33(ps/nm/km) (y-polarized mode) at 1.55μm can be achieved. Morever, the fluctuations of the dispersion with fiber parameters are very small. The simulation results show that our proposed PCF are robust to fabrication imperfections.
Measurement of bubble field in the liquid for the simulation of cloud droplets particle detection using digital holography
Author(s):
Xiaotao Yu;
Yizhen Jia;
Feng Ji;
Baosheng Li
Show Abstract
The cloud in the high altitude is usually in the gas-liquid mixed state, this paper simulates the environment of the cloud particle using bubble field in the liquid. The paper research the gas-liquid mixture via measuring the size and 3D position of the bubble using a digital in-line holographic imaging system. The design of the optical system and the algorithm of reconstruction, recognition and extraction about the digital hologram is presented. The digital holography deserves to be selected as the projection to measure the bubble field because of advantages such as being able to record and reconstruct the three-dimensional position information, avoiding disturbing the object and insuring the instantaneity during the measurement. The optical system and the algorithm about the digital program have been completed, the hologram of bubbles in the liquids recorded by CCD, the hologram reconstruction using the digital hologram after denoising processing is accomplished. The character of cloud particles can be measured by using holography after analyzing the parameter of the bubbles.
The development of x-ray single photon detector
Author(s):
Dongdong Jin;
Huijun Hu;
Xinbo Chu;
Wencong Wang;
Yuxiang Luo;
Shukun Sun;
Shipei Shao
Show Abstract
The effective X-ray single photon detector is one of the key technologies for X-ray pulsar detection and navigation. The detector should have good energy and time characteristics and feasibility to meet the needs of X-ray pulsar single photon detection. In this paper, the main kinds of X-ray single photon detectors at present are introduced. By comparing their advantages, disadvantages and usage in satellite, we will give the development trends for the use of X-ray single photon detectors in X-ray pulsar navigation. Finally, we will introduce other new types of X-ray single photon detectors for the future use.
Experiment research on inertia-aided adaptive electronic image stabilization of optical stable platform
Author(s):
Xiaodong Lu;
Tianze Wu;
Jun Zhou;
Bin Zhao;
Xiaoyuan Ma;
Xiucheng Tang
Show Abstract
An electronic image stabilization method compounded with inertia information, which can compensate the coupling interference caused by the pitch-yaw movement of the optical stable platform system, has been proposed in this paper. Firstly the mechanisms of coning rotation and lever-arm translation of line of sight (LOS) are analyzed during the stabilization process under moving carriers, and the mathematical model which describes the relationship between LOS rotation angle and platform attitude angle are derived. Then the image spin angle caused by coning rotation is estimated by using inertia information. Furthermore, an adaptive block matching method, which based on image edge and angular point, is proposed to smooth the jitter created by the lever-arm translation. This method optimizes the matching process and strategies. Finally, the results of hardware-in-the-loop simulation verified the effectiveness and real-time performance of the proposed method.
Effects of atmospheric turbulence on the return photon flux of sodium laser guide star
Author(s):
Xiangyuan Liu;
Xianmei Qian;
Chuanyu Fan;
Chengtao Du;
Chengling Lu;
Lei Zhang;
Huan Yang
Show Abstract
The circular-polarized laser can excite Sodium Laser Guide Star (SLGS) to obtain a large number of the return photons. Re-pumping technology can further enhance the return photon flux of SLGS. But laser propagating in the atmosphere suffers the atmospheric turbulence which causes the stochastic distributions of laser intensity in mesosphere. This leads to the fluctuations of return photon flux as the strength of atmospheric turbulence. We study effects of atmospheric turbulence on the return photon flux of SLGS under the Hufnagle-vally5/7(HV5/7), Greenwood and Mod-HV models by numerical simulation. Results show that both the return photon flux and fluctuations under the strong atmospheric turbulence are more than those under the weak one. Comparing re-pumping with no re-pumping, increment of the return photon flux under the three atmospheric turbulence models increase with the decreasing strength of atmospheric turbulence. But the fluctuations of the return photon flux greatly decrease for re-pumping.
Fast defect detection for large scale photoelectric devices utilizing compressive sensing
Author(s):
Quan Lei;
Kai Xie;
Liu Yan
Show Abstract
Conventional scanning method for photoelectric devices is slow and ineffective, especially in large scale applications. Motivated by the fact that the failed or defected components are sparse, this paper proposed a fast scanning method utilizing compressive sensing. The proposed method measures the total output of the sample device under pattern controlled structured light beams. With a few numbers of photo-electric current measurements, the defected components are located in the compressive sensing manner. The concept of propose method and the detection probabilities of the proposed method are evaluated. Simulation results indicating that the sparse defects can be compressively located using a few measurements, and the detection speed can be accelerated by 10 times when the ratio of defects is less than 1.5%; this detection probability is sufficient for real application. The additional advantages of proposed detection system are that no mechanical movement component is required, and the testing for each single cell is no longer required, since the system measures the total output of the whole panel. This feature brings great benefits to the applications for testing the devices that have been assembled or installed.
Research on high-precision polarized laser interferometer
Author(s):
Wanduo Wu;
Tingting Wu;
Qiangxian Huang;
Chaoqun Wang;
Rui Zhang
Show Abstract
The zero initial optical path difference, the integral optical path layout and the polarization interference technique are adopted to design quadruplicated polarized laser interferometer measuring system. The factors and design requirements which affect high-precision interferometer are analyzed. In order to reduce DC offset error, unequal amplitude error and non-orthogonal error, four orthogonal measuring signals are processed by a series of circuits with differential amplification and orthogonalization functions, and the two ideal orthogonal measuring signals are obtained. Beyond the VC++ environment, combined with the 200 phase subdivision, the resolution of 0.8 nm can be achieved. The measuring results are compensated and corrected according to the environmental parameters. The error sources of the measuring system are analyzed, and the quantitative values of the cosine error and abbe error are given. Compared with the British Renishaw XL-80 high-precision laser interferometer, the experimental results show that the measuring system has high stability and accuracy.
Identification chemical agent simulants by remote infrared spectra with improved artificial neural network
Author(s):
Xiao-qiang Dong;
Teng-xiao Guo;
Yu-Ting Yan;
Ji Wang;
Xu Zhang;
Jun-ming Li
Show Abstract
Remote infrared sensing is a good approach to detect Chemical agents which can prevent operator being poisoned. The pattern recognition algorithms such as artificial neural network are the core of the chemical agent spectra identification subsystem. This paper presents a modified artificial neural network that can effectively train and identify chemical agent remote sensing spectra. The C++ language was used to program the identification software. Then many remote sensing spectra DMMP as chemical agent simulants were used to train the artificial neural network. The results show that the adaptive momentum and adaptive learning rate accelerate the artificial neural network convergence, cross-examination avoids neural network over-fitting, and the modified artificial neural network can be used to identify chemical agents remote sensing spectra perfectly.
Distance measurement for rotation center to measurement table using triangulation method
Author(s):
Xicheng Wang;
Muzheng Xiao;
Chao Wang;
Xin Jin;
Zhijing Zhang;
Kiyoshi Takamasu
Show Abstract
Large aspheric mirrors with diameter over 200 mm are widely used in space communication system, large-scale astronomical telescope and X-ray facilities. However the measurement of these mirrors with large slope is a long-term problem. Scanning deflectometry method using autocollimator with rotary stage was proposed for measuring mirrors with large slope. The repeatability of the method has been confirmed as tens of nanometers. However, the absolute accuracy of the method is not confirmed since the distance between the rotation center of the rotary stage and the mirror under measurement is difficult to measure, which strongly affects the measurement accuracy of scanning deflectometry method. In this paper, we have proposed a triangulation method with CMOS sensor for measuring the distance from the rotation center to the measurement table (marble surface). The error analysis shows that the measurement uncertainty of this measurement method is about 40 microns. The repeated experiments show that the measurement accuracy of the proposed method is 49.7 microns, which meets the requirements of large mirror measurement with tens of nanometers’ uncertainty. This method also provides a new solution for the position measurement of the rotation center of the large scale rotary device.
A portable foot-parameter-extracting system
Author(s):
MingKai Zhang;
Jin Liang;
Wenpan Li;
Shifan Liu
Show Abstract
In order to solve the problem of automatic foot measurement in garment customization, a new automatic footparameter- extracting system based on stereo vision, photogrammetry and heterodyne multiple frequency phase shift technology is proposed and implemented. The key technologies applied in the system are studied, including calibration of projector, alignment of point clouds, and foot measurement. Firstly, a new projector calibration algorithm based on plane model has been put forward to get the initial calibration parameters and a feature point detection scheme of calibration board image is developed. Then, an almost perfect match of two clouds is achieved by performing a first alignment using the Sampled Consensus – Initial Alignment algorithm (SAC-IA) and refining the alignment using the Iterative Closest Point algorithm (ICP). Finally, the approaches used for foot-parameterextracting and the system scheme are presented in detail. Experimental results show that the RMS error of the calibration result is 0.03 pixel and the foot parameter extracting experiment shows the feasibility of the extracting algorithm. Compared with the traditional measurement method, the system can be more portable, accurate and robust.
Expanding the bandwidth of low level photo-electric amplifier using continuous equal-potential shielding
Author(s):
Kai Xie;
Bin Sun;
Xueyou Shi;
Anfeng Huang;
Ruoyao Xi
Show Abstract
For the low level current preamplifier circuits in photo-electric detection, the bandwidth and the low noise characteristics are usually contradictory, because the bandwidth is limited by the high value resistor and its inevitable parasitic capacitances, which together exhibit low-pass characteristics. To expand the bandwidth of low level current amplifier, a novel method is proposed by using continuous equal-potential shielding to eliminate the parasitic capacitances and expand the bandwidth. The shielded resistor contains three layers: the center is high value resistance strip; the top and bottom layers are high conductivity shielding films with same path to center strip. The surrounding electric field energy could be provided by shielding structure instead by high value resistor itself, so the parasitic capacitances would be greatly reduced. In this paper, the principle and the structure of the equal potential shielding are presented, and the possible results are predicted by finite element simulation. The simulation was conducted by the ultra-low current preamplifier with a trans-impedance gain of 50 GΩ. The results indicated that the parasitic capacitances reduced from 1.36×10-2pF to 1.18×10-3pF, meanwhile the bandwidth was expanded from 234.1 Hz to 2.43 kHz with more than 10 times of increase; the rise time decreased from 1.53ms to 0.085ms. The advantage of this method is that the bandwidth could be expanded without extra compensation; meanwhile the shielding layers improve the noise immunity. This method is suitable for the demand of rapid response to low level current in photo-electric detection field, such as scanning tunneling microscopy and laser radar.
Fabrication of GaN quantum dots by MOCVD for intersubband transitions infrared detectors
Author(s):
Zhiqiang Qi;
Rui Yang;
Cheng Zeng;
Wenliang Hu;
Zhijie Zhang;
Chensheng Wang
Show Abstract
The inter-sub-band transitions of GaN quantum dots are in the infrared spectrum, which have enormous potentials in fabrication the high-performance infrared detectors. In this letter, the growth of multi-layer stacks of GaN quantum dots have been grown via MOCVD, including the growth of AlN buffer, GaN quantum dots and AlN caplayer. In the end, the multi-layer GaN quantum dots with uniform-size and excellent optical performance have been obtained, which are verified by the AFM and photoluminescense results.
Extraction of thin occlusions from digital images
Author(s):
Yinlong Li;
Yu Wang;
Yan Piao
Show Abstract
We propose a method to extract thin occlusions from multi-focus images. The occluders are various shapes of arbitrarily thin noise (e.g., fences, window shutters, tree branches and football nets). The proposed method can recognize and extract the thin occlusions in a variety of complex scenes by using color similarity and image registration. Experimental results on real images show the validity of the proposed method.
Simulation analysis for thermo-chromic fiber optic temperature sensing probe
Author(s):
Xueyan Han;
Yinping Dou;
Kewei Huan
Show Abstract
Fiber-optic temperature sensor based on thermo-chromic materials is a kind of effective facility to solve the problem of measuring temperature in the electrical power system. But the measuring range by this method is narrow, it is necessary to improve the measuring range by the means of append an attenuator. In this paper,based on traditional fiber optic temperature sensor , the purpose and principle of thermo-chromic optical fiber temperature sensing probe is introduced. The degree of attenuation of temperature which is obtained through ANSYS software thermal simulation is used as an evaluation index to make the choice of probe structure, and analyzes the result of simulation in detail. Finally, the functional between the temperature of heat source and the temperature of attenuator is fitted. So, this paper could be a reference or an example for the application of fiber-optic temperature sensor based on thermo-chromic materials.
Analysis and design of bridge structure for a micro Fabry-Perot cavity
Author(s):
Yuanyuan Li;
Qinghua Meng;
Sihai Chen;
Yuming Dong
Show Abstract
Abstract—This paper describes a MEMS-based tunable Fabry-Perot filter that can be directly integrated on a detector. The Fabry-Perot filter consists of two parallel mirrors and lets the light with particular wavelength pass through. The wavelength depends on the gap between the mirrors. The gap of the micromechanical Fabry-Perot filter can be changed by applying a voltage to the mirrors, an electrostatic force inducing an attraction between the substrate and the top mirror. Based on the comprehensive analysis of the working principle of the micro F-P cavity filter, the optimum tuning scheme of micro F-P cavity filter is established. A simulation of the mechanical behavior was performed based on finite elements, using ANSYS software. We finally establish the L-arm type cantilever to support cavity structure, the micro-bridge can achieve a considerable range of tuning; relatively high fill factor, filter light leakage is avoided; the high abilityto keep parallel can achieve high precision filtering effect; structural stability, it can resist the residual stress of manufacture. This MEMS F-P tunable filter can be a potential application in spectroscopic sensing and optical communication system.
Coherent noise reduction in digital holographic interferometry by slightly rotating object
Author(s):
Zheng Zhong;
Wen Xiao;
Feng Pan;
Leiping Che
Show Abstract
The coherent noise degrades the imaging quality and resolution in digital holographic interferometry. A method to reduce coherent noise by the way of slightly rotating object is proposed. Firstly, a series of digital holograms with different coherent noise patterns were recorded by slightly rotating object. Secondly, the different holograms were reconstructed individually, and the differences between the reconstructed complex amplitudes due to the rotation of the object were removed by using phase compensation and image registration algorithms. Thus, multiple identical retrieved images of object with different coherent noise distributions were obtained. Finally, the coherent noise was reduced by a proper averaging process for amplitude and phase images. Moreover, Non-correlation between two speckle patterns can be achieved by rotating very small angle proven by means of computing the correlation between the circle speckle spots. The experimental results and evaluations are given to confirm the proposed method.
Blind image restoration and segmentation via decoupled adaptive Mumford Shah model
Author(s):
Zhangqin Jiang;
Fengwen Mi;
Zeyang Dou
Show Abstract
A new model that can simultaneously do blind restoration and segmentation task is proposed in the paper. The new model belongs to the variant of Mumford Shah model. In order to promote the computational efficiency, the restoration part and segmentation part are decoupled from the original model. The blind image restoration part is based on the variable exponent regularizer to accurately estimate both piecewise constant point spread functions and smooth point spread functions. The segmentation part is the explicit edge indicator function obtained from the original model. The new model can be efficiently solved using split bregman framework. Numerical experiments show that the new algorithm produces promising results and robust to noise.
Parallel pipeline algorithm of real time star map preprocessing
Author(s):
Hai-yong Wang;
Tian-mu Qin;
Jia-qi Liu;
Zhi-feng Li;
Jian-hua Li
Show Abstract
To improve the preprocessing speed of star map and reduce the resource consumption of embedded system of star tracker, a parallel pipeline real-time preprocessing algorithm is presented. The two characteristics, the mean and the noise standard deviation of the background gray of a star map, are firstly obtained dynamically by the means that the intervene of the star image itself to the background is removed in advance. The criterion on whether or not the following noise filtering is needed is established, then the extraction threshold value is assigned according to the level of background noise, so that the centroiding accuracy is guaranteed. In the processing algorithm, as low as two lines of pixel data are buffered, and only 100 shift registers are used to record the connected domain label, by which the problems of resources wasting and connected domain overflow are solved. The simulating results show that the necessary data of the selected bright stars could be immediately accessed in a delay time as short as 10us after the pipeline processing of a 496×496 star map in 50Mb/s is finished, and the needed memory and registers resource total less than 80kb. To verify the accuracy performance of the algorithm proposed, different levels of background noise are added to the processed ideal star map, and the statistic centroiding error is smaller than 1/23 pixel under the condition that the signal to noise ratio is greater than 1. The parallel pipeline algorithm of real time star map preprocessing helps to increase the data output speed and the anti-dynamic performance of star tracker.
Different source image fusion based on FPGA
Author(s):
Xiao Luo;
Yan Piao
Show Abstract
The fusion technology of video image is to make the video obtained by different image sensors complementary to each other by some technical means, so as to obtain the video information which is rich in information and suitable for the human eye system. Infrared cameras in harsh environments such as when smoke, fog and low light situations penetrating power, but the ability to obtain the details of the image is poor, does not meet the human visual system. Single visible light imaging can be rich in detail, high resolution images and for the visual system, but the visible image easily affected by the external environment. Infrared image and visible image fusion process involved in the video image fusion algorithm complexity and high calculation capacity, have occupied more memory resources, high clock rate requirements, such as software, c ++, c, etc. to achieve more, but based on Hardware platform less. In this paper, based on the imaging characteristics of infrared images and visible light images, the software and hardware are combined to obtain the registration parameters through software matlab, and the gray level weighted average method is used to implement the hardware platform. Information fusion, and finally the fusion image can achieve the goal of effectively improving the acquisition of information to increase the amount of information in the image.
Visible detecting system for atmospheric coherence length
Author(s):
Yang Du;
Wenju Wang;
Xiaojun Zhou
Show Abstract
The atmospheric turbulence has a strong influence on laser transmission in the atmosphere. As a important parameter, atmospheric coherence length measures the atmospheric turbulence and it is very significant to determine the atmospheric conditions. This system puts into use visible wavelength is 532 nm ~ 680 nm , the charge coupled device size is 12.7 mm . The three component mechanically compensating zoom detecting system is designed, it has simple structure, low cost and real-time monitoring.
Detection of thermal infrared oil tank targets based on SVM classification
Author(s):
Lan Ma;
Xiaoyong Chen
Show Abstract
In this paper, a method for selecting and testing the features of thermal infrared (TIR) remote sensing images of oil tank targets is proposed to address deficiencies in the recognition of TIR images due to their characteristic low contrast, striping noise, and low spatial resolution. An evaluator was used to select 22 out of 29 features including texture and geometry, and training was conducted for samples with respect to these features through the libSVM (a support vector machine). This could lead to an effective detection of quasi-circular oil tank targets with a certain degree of robustness. The one-dimensional statistical features (pixel value, mean value, variance, mid-value, and gray level histogram), LBP features, EOH features and invariant moment features are more meaningful for the recognition of TIR remote sensing images of oil tank targets; the proper selection of training samples of oil tank with background is quite important for the effectiveness of detection; difference in detection windows can also influence the effect of detection. A method for selecting and testing the features of oil tank targets in TIR remote sensing images is proposed for effective classification of such targets under certain conditions.
Research on the dual-waveband thermometry model for dim small targets
Author(s):
Xiaoxiao Wu;
Yanbing Dong;
Hongxia Mao;
Zheng Liu
Show Abstract
In the field of target recognition, target detection and tracking can be achieved by measuring the temperature of it. At present, most of the temperature measurement technologies are used for surface targets. Dim small targets are often faced with several problems during temperature measurement, such as the low filling rate of field, unknown emissivity and serious noise interference. Referring to the current issues about dim small targets temperature measurement, this paper built a new model for dual-waveband thermometry of them based on the wavelet analysis theory and neural network theory, obtaining the dual-waveband thermometry results of the dim small targets which are very close to the theoretical temperature. What’s more, the model validation is carried out by using the measured data of dim small targets. Analysis results show that the new model is more suitable to measure the dim small targets temperature of the radiation intensity signal-to-noise ratio within the scope of 3-8, laying the theoretical foundation and technical foundation for the recognition of dim small targets.
Study of large-scale terrain three-dimensional visualization in optoelectronic detection
Author(s):
Qiang Gao;
Wentao Jiang;
Ming Ji;
Lan Pang;
Xuezhi An;
Zheng Zhang;
Weidong Huang;
Qinglin Zhao;
Hui Li
Show Abstract
Introduces the image and spatial data fusion in photoelectric detection application. Focus on the optimization of 3D scene reconstruction. In airborne imaging applications, aiming at the problems of massive terrain data, this paper proposed a dynamic data scheduling strategy which is based on state-tree from simplification, and present a terrain data dynamic schedule framework from render optimization. For the suggested optimized procedure and framwork, give a experiment and couclusion based on programmimg, it prove that the suggested dynamic schedule strategy in this paper could fastly construct three-dimensional scene in flight simulation, could speed up the three-dimensional visulization, it could meet the practical requiremnet of engineering in flight simulation.
Non-uniformity calibration for MWIR polarization imagery obtained with integrated microgrid polarimeters
Author(s):
Hai-Zheng Liu;
Ze-Lin Shi;
Bin Feng;
Bin Hui;
Yao-Hong Zhao
Show Abstract
Integrating microgrid polarimeters on focal plane array (FPA) of an infrared detector causes non-uniformity of polarization response. In order to reduce the effect of polarization non-uniformity, this paper constructs an experimental setup for capturing raw flat-field images and proposes a procedure for acquiring non-uniform calibration (NUC) matrix and calibrating raw polarization images. The proposed procedure takes the incident radiation as a polarization vector and offers a calibration matrix for each pixel. Both our matrix calibration and two-point calibration are applied to our mid-wavelength infrared (MWIR) polarization imaging system with integrated microgrid polarimeters. Compared with two point calibration, our matrix calibration reduces non-uniformity by 30~40% under condition of flat-field data test with polarization. The ourdoor scene observation experiment indicates that our calibration can effectively reduce polarization non-uniformity and improve the image quality of our MWIR polarization imaging system.
Research on visible light communication system based on white LEDs
Author(s):
Jing-feng Zang;
Yan Piao
Show Abstract
Visible light LEDs are being used for indoor optical wireless communication system as well as the illumination of rooms. The visible light communication system based on LEDs can attain high luminosity as a lighting source, and thus high quality transmission for an optical wireless system. In indoor diffuse optical wireless links multi-path dispersion limits the maximum transmission data rates. The relation between optimal strategies of light source and received optical power has been discussed. The optical diversity reception technology has been given to get rid of intersymbol interference and increase the SNR. And the model of the optical detector's layout is given. The system simulation model is built, and the relation curve between BER and root-mean-square delay spread of OOK-NRZ and OOK-RZ is given.
A method for measuring object distance on the plane based on monocular vision
Author(s):
Qian Zhang;
Pucheng Zhou;
Mogen Xue
Show Abstract
Plane measurement is an important task in image processing and computer vision. In this paper, we present a kind of plane measurement method for monocular vision, which calculates the image magnification by controlling the camera movement, the height of object and camera focal length. We can finally get the measurement results. Experimental results show that the proposed method can measure the distance more accurately. What’s more, it has the advantages of high universality, simple steps and small error.
The conditions for femtosecond laser melting of silicon under two different models
Author(s):
Zhi-ming Li;
Xi Wang;
Jin-song Nie
Show Abstract
An investigation of silicon melting occurring under femtosecond laser irradiation has been presented, The two-temperature model and photoionization model are introduced to calculate the free-carrier intensity’s evolution with time. In both models, the electrons density’s evolution under laser fluence F0 = 0.2 ,0.3, 0.5J / cm2 are performed. The maximum density reaching the threshold density for SPP excitation by these two model are discussed. For both single pulse and double pulse, according to the simulation data, the two temperature model have a more agreement with the experiment results.
Modeling of space-based single photon detection for space non-cooperative target
Author(s):
Jinghao Zhang;
Yongchao Zheng;
Weidong Shang;
Zizheng Gong
Show Abstract
In order to detect dangerous space non-cooperative targets, we have researched the technology of single photon laser detection. A single photon detection model which includes relative radial velocity between space-based detector and target was proposed, as well as, we analyzed the detection method of non-cooperative targets on a space-based plat-form. The results of simulations show that single photon laser detection can effectively detect the target of the distance 160 km and velocity 5 km/s under the load requirements of the space-based platform, its ranging accuracy could be improved 2~3 orders of magnitude compared with world ground-based traditional detection technology for space non-cooperative targets , and it can effectively reduce the collision probability of spacecraft
Implementation of camera link standard video display in HDMI format based on FPGA
Author(s):
Hao-yue Chen;
Wen-tao Jiang;
Tao Li;
Jun Qian;
Xuan Liu
Show Abstract
In this paper, we propose a high definition video display format conversion system based on FPGA which converts the Camera Link format video data (1928×1084, progressive scanning, 33 fps) into the HDMI format video (1920×1080p, 30 fps), and then output to the HD display device with a HDMI interface. This system can solve the display incompatible problem between different HD video frame rates. Experimental results show that the proposed system realizes a real-time video format conversion; furthermore, the output video image has a good quality.
Fabrication of the metal wire-grid polarizer in visible light
Author(s):
Quan Liu;
Jianhong Wu;
Yang Zhou
Show Abstract
The polarization characteristics of the metal wire-grid polarizer are investigated by Finite Difference Time Domain method. To achieve a high extinction ratio and transmissivity in visible light, the metal wire-grid profile was optimized. The simulation results show that the period should be less than 200 nm. When the period, the glass substrate etching depth and the Al groove depth of metal wire-grid were at 180nm, 20nm and 120nm respectively, the extinction ratio could reach the maximum 40 dB; the transmissivity could reach the maximum 85%. Herein, considering the high reflection of metal aluminum in the manufacturing process, we propose using the copper as anti-reflection coating. Finally, a prototype of the metal wire-grid polarizer has been fabricated by holographic-immersion lithography and ion beam etching.
Intrinsic fluorescence spectra of tryptophan, tyrosine and phenyloalanine
Author(s):
Hui Yang;
Xue Xiao;
Xuesong Zhao;
Yan Wu
Show Abstract
This paper presents the intrinsic fluorescence spectra characteristics of tryptophan, tyrosine and phenyloalanine measured with 3D fluorescence spectrophotometer. Two strong fluorescence peaks of tryptophan locate at λex/λem=230/348nm and 280/348nm, three strong fluorescence peaks of tyrosine locate at λex/λem=202/304nm, λex/λem=220/304nm and 275/304nm, and two fluorescence peaks of phenyloalanine locate at λex/λem=210/280nm and λex/λem=260/280nm were found. The linear relationship of fluorescence intensity to solution concentration were also observed in condition of low solution concentration. The influence of pH of solution to the fluorescence intensity was also measured and discussed.
Decline analysis of vacuum level in ultra high vacuum system
Author(s):
Hui Liu;
Chang Chen;
Feng Shi;
Hong-chang Cheng;
Sen Niu;
Yuan Yuan;
Zhuang Miao;
Xiao-hui Zhang
Show Abstract
Vacuum technology is extensively used in space science, nuclear energy, surface science, materials science, electric vacuum industry, microelectronics, semiconductor, metallurgy, and so on. More and more fields need ultra high vacuum (UHV) or extreme high vacuum (XHV) for scientific research and production. Both the rigorous vacuum processing technics and highly developed sophisticated vacuum technology are the necessities for the acquisition and conservation of UHV or XHV ambience. In this paper, a vacuum decline was analyzed and the UHV system was recovered. Using the residual gas analyzer to measure the partial pressure of residual gas and identify the type of gas, the outgassing source was found out by comparing the measure results. The UHV system was recovered back to 10-9Pa through treatment. The residual gas analyzing method can effectively identify the type of gas about outgassing, narrow the scope of outgassing subassembly, shorten the vacuum system recovery time, and improve work efficiency. The method of determining the outgassing source by residual gas analyzer can be applied in the fields of UHV and XHV, and it has a certain reference significance for further improving the system vacuum degree.
Geometrically tunable Fabry-Perot filters based on reflection phase shift of high contrast gratings
Author(s):
Liang Fang;
Zhendong Shi;
Xin Cheng;
Xiang Peng;
Hui Zhang
Show Abstract
We propose tunable Fabry-Perot filters constituted by double high contrast gratings (HCGs) arrays with different periods acting as reflectors separated by a fixed short cavity, based on high reflectivity and the variety reflection phase shift of HCG array which realize dynamic regulation of the filtering condition. Single optimized HCG obtains the reflectivity of higher than 99% in a grating period ranging from 0.68μm to 0.8μm across a bandwidth of 30nm near the 1.55μm wavelength. The filters can achieve the full width at half maximum (FWHM) of spectral line of less than 0.15nm, and the linear relationship of peak wavelengths and grating periods is established. The simulation results indicate a potential new approach to design a tunable narrowband transmission filter.
Resolution improved monochromator based on tunable Fabry-Perot filter and grating hybrid modulator
Author(s):
Liang Fang;
Xin Cheng;
Xiang Peng;
Hui Zhang
Show Abstract
A resolution improved monochromator based on tunable Fabry-Perot (F-P) filter and grating hybrid modulator was presented. The light was firstly filtered by the tunable F-P filter and then diffracted by the grating. The tunable F-P filter was used to achieve multi-orders narrow linewidth monochromatic light spectrally and the grating was in charge of separating the multi-orders monochromatic light spatially. By adjusting the rotation angle and the cavity length of the hybrid modulator, the wide spectral range can be achieved. A visible hybrid modulator was designed and the simulation results demonstrated the resolution of a monochromator system was improved in the spectral range of 400~800nm.
Restoration of the infrared image blurred by motion
Author(s):
Ningming Wang;
Jing Wang;
Yazhou Zhang;
Xianzhong Sun
Show Abstract
Restoring blurred image，as one of the hot issues in the field of image processing，has important significance in improving the image quality. In recent years, a variety of methods for removing motion blur of an image have been proposed, but most of the algorithms are too complex and not applied. This paper educes an efficient algorithm for motion-blurred image. According the temporal profile of the infrared detector, point spread function (PFS) of the uniform linear motion-blurred image is discussed. The profile of the PSF is acquired by iterative Weiner-filter. Experimental results show that the method has accurate and applied performance for infrared blurred image got from actual system.
Effect of ZnO buffer layer on phase transition properties of vanadium dioxide thin films
Author(s):
Huiqun Zhu;
Lekang Li;
Chunbo Li
Show Abstract
VO2 thin films were prepared on ZnO buffer layers by DC magnetron sputtering at room temperature using vanadium target and post annealing at 400 °C. The ZnO buffer layers with different thickness deposited on glass substrates by magnetron sputtering have a high visible and near infrared optical transmittance. The electrical resistivity and the phase transition properties of the VO2/ZnO composite thin films in terms of temperature were investigated. The results showed that the resistivity variation of VO2 thin film with ZnO buffer layer deposited for 35 min was 16 KΩ-cm. The VO2/ZnO composite thin films exhibit a reversible semiconductor-metal phase transition at 48 °C.
Design and application of hyperspectral post-launch cross-calibration system
Author(s):
Wen-bin Xu;
Xiao-bing Zheng;
Jun-wei Li
Show Abstract
Due to the new requirements of multi-site、multi-time、multi-satellites and highfrequency post-launch calibration, the hyperspectral post-launch cross-calibration system is developed. The system integrating global calibration-site network、calibration task automatic planning software and hyperspectral cross-calibration software can efficiently execute post-launch cross-calibration and dynamic performance evaluation. The application of the hyperspectral post-launch cross-calibration system is introduced. Hyperspectral imager Hyperion is used as reference sensor and HJ-1A/HSI is used as sensor to be calibrated. The system is used to acquire the cross-calibration coefficients of all HSI bands. The average differences of all HSI bands is 6.34% when cross-calibration coefficients are compared with site-calibration coefficients. The application feasibility of the post-launch cross-calibration system is validated preliminarily.
The research status and application of hyperspectral image target detection
Author(s):
Yuejiao Sun;
Wuhu Lei;
Xiaodong Ren
Show Abstract
Target detection for hyperspectral imagery has important academic value and prospective applications both in civiland military areas. And it has been a hot spot in the areas of target recognition and remote sensing information processing. Based on the principle and research status of hyperspectral imaging, this paper surveys the potential typical applications of target detection for hyperspectral imagery. Then, the algorithm theories are summarized. In the end, the prospect of target detection of hyperspectral remote sensing images is discussed.
Collaborative dictionary learning with structured incoherence for target detection in hyperspectral imagery
Author(s):
Yidong Tang;
Shucai Huang;
Aijun Xue
Show Abstract
Although sparse representation based classification (SRC) has gained great success, doubts on the necessity of sparse constraint come in recent years. And collaborative representation based classification (CRC) has attracted much attention from researchers in fields of signal processing, image processing and pattern recognition. In this paper, an algorithm called collaborative dictionary learning with structured incoherence (CDLSI) is proposed for collaborative representation based detection (CRD), which can be viewed as a binary classification problem, in hyperspectral imagery (HSI). An inter-class incoherence term is added to make sub-dictionaries to be as independent as possible. During the optimizing procedure, sub-dictionaries are updated atoms-by-atoms with metaface method. Specifically, considering the non-sparse representation of CRC, the coefficients are iteratively optimized with l2 -norm regularization during the coding procedure in CDLSI. Once the sub-dictionaries are obtained, the collaborative representation based technique is then used for detection. The proposed algorithm is applied to several real hyperspectral images for detection. Experimental results confirm the effectiveness of the proposed approach, and prove the superiority to the traditional algorithms.
Electronic structure and optical properties of P-doped GaAs film
Author(s):
HongLi Shi;
Bin Ren;
HongChang Cheng;
XiaoJun Yang
Show Abstract
The electronic structure and optical properties of pure and P-doped cubic-blende gallium arsenide (GaAs) for different P constants (x=0, 0.125, 0.25, 0.375) have been studied by the first-principles projected augmented plane potential approach based on the density functional theory and the generalized gradient approximation method. It shows that the P-doped material has a smaller lattice constant, which resulted in a local lattice distortion. The minimum of the conduction band moves to high energy level and the band gaps gradually become wide with gradual increase concentration of P impurity. The dielectric function are calculated based on Kramers-Kroning relations. The optical property studied from the calculated absorption coefficients shows that the adsorption peaks change obviously in the visible light wavelength area for the P-doped GaAs system.
No scanning depth imaging system based on TOF
Author(s):
Rongchun Sun;
Yan Piao;
Yu Wang;
Shuo Liu
Show Abstract
To quickly obtain a 3D model of real world objects, multi-point ranging is very important. However, the traditional measuring method usually adopts the principle of point by point or line by line measurement, which is too slow and of poor efficiency. In the paper, a no scanning depth imaging system based on TOF (time of flight) was proposed. The system is composed of light source circuit, special infrared image sensor module, processor and controller of image data, data cache circuit, communication circuit, and so on. According to the working principle of the TOF measurement, image sequence was collected by the high-speed CMOS sensor, and the distance information was obtained by identifying phase difference, and the amplitude image was also calculated. Experiments were conducted and the experimental results show that the depth imaging system can achieve no scanning depth imaging function with good performance.
The research of semiconductor photon up-convert sensor and its applications
Author(s):
Xinbo Chu;
Dongdong Jin;
Huijun Hu;
Jingjing Li;
Yuxiang Luo;
Wencong Wang;
Ruiyuan Pan;
Shipei Shao
Show Abstract
Semiconductor photon up-converter that can convert infrared to visible light has great application potential in area of new type infrared imaging, photoelectric alarming, and atmospheric monitoring. Based on its working mechanism, this paper introduced the types of up-convert sensor, displayed its advantage when it was applied to infrared imaging. This paper also gave a detailed review about the development of semiconductor photon up-converter recent years. The organic-inorganic hybrid method can suitably combine the superiority of both material systems and complement each other's advantages. Finally, it may promote the development of low-cost，wavelength variable and imaging directly infrared imaging system.
Study on flawed surface of GaAs epitaxial wafer in the process of wet chemical etching
Author(s):
Hongjin Qiu;
Canglu Hu;
Chaxia Peng;
Kai Qiao;
Xin Guo;
Xuchuan Liu
Show Abstract
The flawed surface of GaAs/GaAlAs heterointerface after wet etching by H2O2 and NH4OH based etch ant was studied in this work. The results showed that the surface of GaAs/GaAlAs heterointerface had convex point, etching pits, pinhole, fog point, and friction scratches were investigated with a etch step measurement. And imprinting the main reasons for the formation of the etching surface defects of GaAs/GaAlAs are the poor quality of epitaxial materials, the contamination of materials surface, the unclear interface of oxidation and doping, the inhomogeneity of concentration and the operation errors. The selective etching of the GaAs/GaAlAs material eliminates some flaws and improves the quality of the etching surface of the GaAs/GaAlAs material.
Simulative calculation of temperature variation and infrared detection probability of the desert ground target
Author(s):
Bao-guo Wang;
Yong-jie Xie;
Yao-chen Yuan;
Wen-ming Zhang
Show Abstract
The temperature variation and the infrared detection probability of the ground target in desert was studied through simulative calculation. The model of temperature variation of the ground and the target was established, of which the ground temperature variation was simplified as a one dimensional transient heat conduct model and the heat equilibrium state of the target was hypothesized as two basic idealized types. Furthermore, the calculation formula of every radiation part such as the sun direct radiation and scatter radiation, atmosphere long wave radiation, atmosphere convective heat conduction, etc., were analyzed and established. Afterwards, the model was constructed and calculated using Comsol software. Finally, the infrared detection probability of the target was calculated using NETD of the infrared imager under the point target hypothesis.
Infrared dim moving target tracking via improved context learning
Author(s):
Jin Qian;
Huixin Zhou;
Kun Qian;
Dong Zhao;
Hanlin Qin;
Shangzhen Song;
Zhenwu Wu
Show Abstract
It is very critical that make full use of the local information for infrared dim and small target tracking. In this paper, an effective and fast algorithm based on the context learning is proposed to track infrared dim moving target. Firstly, the principle of the spatio-temporal context learning algorithm is described and the tracking deviation is analyzed. Then, a correlation filter is utilized to get a rational context prior for the dim moving target, the advantage is that the prior considers the image intensity information between a target and its surround pixels. Furthermore, a Gaussian high-pass filter is introduced to extract an accurate spatial context, which has little influence caused by the cluttered background. At last, the tracking problem is posed by computing a confidence map which takes into account sufficient information of a dim target and its surround background. Since the proposed algorithm is realized using fast Fourier transform, it is easy to be real-time. The experiments on various clutter background sequences have validated the tracking capability of the proposed method. The experimental results show that the proposed method can provide a higher accuracy and speed than several classical algorithms, including the improved Template Matching algorithm, the Temporal-Spatial Fusion Filtering algorithm and the Moving Pipeline Filtering algorithm.
Study on the FOV quality test of the micro channel plate with anti ion feedback by ultraviolet photoelectric method
Author(s):
Xiangxin Li;
Yufeng Zhu;
Ni Zhang;
Ziheng Hao
Show Abstract
A new method of FOV quality test of the anti ion feedback microchannel plate was introduced, Ultraviolet Photoelectric Method, and the principle and the structure of the device were given. The test principle and device structure are given. The problems in the testing, including the mutual relationship between the UV transmittance and the quantum efficiency of the Au cathode, and the influence of the photoelectrons on the field of view caused by the UV-excited MCP were discussed. The advantages of the UV photoelectron method in the field defect detection were compared. Which provided a basis for the application of Ultraviolet Photoelectric Method and proves the research direction.
Space-based multispectral image motion object detection and velocity estimation method
Author(s):
Chunyu Shi;
Chunping Zhou
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The space-based information moving target detection method is mainly based on the traditional SAR/GMTI implementation, but at present our country still does not have to orbit satellite SAR/GMTI. This paper presents a minimal time difference with multi spectral image channel method for moving target detection, the multispectral image channel cannot imaging flaws to the clever use, moving object detection and velocity estimation.
Remote sensing image target detection method based on corner probability model
Author(s):
Chunyu Shi;
Lei Ma;
Chunping Zhou;
Lin Cai
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This paper presents a novel method to describe the contour in the complex background, features are extracted object contour partial occlusion or lack of conditions, and effectively detect the image features. The validity and robustness of the proposed method is proved by the experiment of remote sensing image.
Corona discharge detection based on UV pulse method
Author(s):
Taifei Zhao;
Yangfei Lei;
Peng Hou
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With the reforming and opening up, as well as the rapid economic development of china, the shortage of electricity resources in the eastern region has become a problem. Therefore, we have started the program of power transmission from west to east, and have speeding up the development of high-voltage transmission technologies with high efficiency, long-distance, and high-capacity. An important issue during the power transmission is the insulation design. Recently, there have been more and more power grid accidents are escalating. Therefore, timely discovering an forecasting insulation deteriorations using advance detection techniques is of special practical significance for the equipment maintenance and repairing , and especially avoiding power accidents. On this basis, this paper carries out the research of high-voltage transmission line corona discharge detection system using the solar blind and FPGA. The experimental result shows that our system can amplify week signals with different intensity of 5100~5000100 times, with high sensitivity and anti-interference ability. The result also proves that this system can effectively detect the ultraviolet pulse light signal of the corona discharge insulation.
Self-checking pantograph-catenary arcing fluorescent detection system based on fiber sensing
Author(s):
Yuming Dong;
Yizhou Zhang;
Liang Zhang;
Peng Liu;
Liangpei Chen
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This paper develops a promising low-priced optical fiber arcing detection system for measuring pantograph-catenary contact-loss. The system collects the ultraviolet light by UV lens. The filter cuts off visible light to reducing environmental disturbance. Ultraviolet light of arcing is transformed to visible one by fluorescent material, which is packaged on the fiber endface and has a high transforming efficiency in ultraviolet band. This optical fiber arcing detection system is equipped with self-checking pulsed light to monitoring the status of the detection system. The arcing energy is estimated by the relationship between the intensity of ultraviolet light and the output voltage signal.
The formation mechanism and stability of vortex in cold BEC
Author(s):
Rui Cheng;
Jingbo Yao;
Yuan Ren
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With high precision and sensitivity, quantum gyroscope has become a research hotspot of inertial technology in recent years. Because the Bose-Einstein Condensate (BEC) in atomic gas has more condensate atoms, atomic gas is pure and thin, and there is no friction in atoms, the matter–wave gyroscopy with counter-rotating vortex superpositions has great potential of higher sensitivity, higher precision, and miniaturization. The basic mechanism and sensitivity of the matter– wave gyroscopy with counter-rotating vortex superpositions were analyzed, and the interaction between superposition of vortex beams and BEC atomic gases were studied, it is Stimulated Raman Adiabatic Passage (STIRAP). In the study, the outstanding issue that the gyroscopy is difficult to obtain stable vortices with high order orbital angular momentum was clarified by theoretical derivation on the base of Gross-Pitaevskii equation which is the basic equation in BEC. For solving the above problems, the scheme which is easy to achieve based on Sombrero potential trap was proposed.
Mechanism interpretation of the vortex beam rotational Doppler effect
Author(s):
Gang Wang;
Yuanwen Cai;
Yuan Ren;
Lu Xie;
Zhengliang Liu
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Vortex beam rotational Doppler effect has been verified by experiments. But its mechanism interpretation is still being studied. Firstly, this paper introduces the vortex beam and its rotational Doppler effect, and then explains vortex beam rotational Doppler effect based on the Doppler effect and Sagnac effect. In 2014, professor Miles Padett proposed that the classical Doppler effect can be used to explain vortex beam rotational Doppler effect. This thesis gives its complete process by utilizing resolution of vectors on the spiral wave fronts. Based on the Sagnac effect, this paper uses the principle of independently propagating to deduce the formula of the superimposed vortex beam rotational Doppler effect. The mechanism derivation results agrees with the experimental results, which proves the accuracy and advantage of the mechanism derivation methods in this article. Moreover, this thesis also discovers the high order correction terms of the formula.
Influence of Nb doping on the phase transition properties of VO2 thin films prepared by ion beam co-sputtering deposition
Author(s):
Huiqun Zhu;
Pengfei Li;
Lite Zhao;
Jiahuan Liu
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The Nb-doped VO2 thin films were successfully prepared on the glass substrates by ion beam co-sputtering at room temperature and post annealing under the air condition. The effects of the preparation processing and Nb doping on the thermal hysteresis loop and phase transition temperature of the VO2 thin films were analyzed by resistancetemperature measurement. The results show that Nb doping significantly changes the surface morphologies of VO2 thin films, and Nb-doped VO2 thin films exhibit VO2(002) preferred orientation growth with greatly improved crystallinity and orientation. Compared with pure VO2, the phase transition temperature of Nb-doped VO2 thin films drops to 40 ºC, and the width of thermal hysteresis loop narrows to 8 ºC. It is demonstrated that Nb-doped VO2 thin films prepared by ion beam co-sputtered at room temperature have an obvious thermal sensitive effect, and keep a good characteristic from metal to semiconductor phase transition.
The 1064nm quadrature squeezed state preparation of applied to quantum detection
Author(s):
Zhiqiang Wu;
Xuling Lin;
Song Yang;
Xuan Zhang;
Yaohui Zheng
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Squeezed state light field can surpass the shot noise limit and improve the signal-to-noise ratio of the sensor measurement. In this paper, based on optical parametric amplification (OPA), we present employed a semi-monolithic cavity and miniaturization design of optical parametric amplifier (OPA) to improve system stability. The infrared spectrum 1064nm quadrature squeezed state field of noise squeezing degree 6.75dB is obtained by pumped the PPKTP crystal via 532nm laser. This work provides a practical light source for quantum sensing detection.
Monte Carlo method-based dynamic simulation of underwater optical transmission characteristics
Author(s):
Yuan-ming Ding;
Bo Song;
Na-na Li
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Attenuation coefficient of seawater channel is not only related to the wavelength of optical, but also attenuation particle distribution, so the energy attenuation coefficient of the optical actual transmission changes with the attenuation particle distribution in the seawater, yet in the current underwater optical transmission simulation study, mostly adopts the method of selecting wavelength to determine the attenuation coefficient. Based on the existing of the Monte Carlo method, using the inverse function of modified Henyey Greenstein function to determine the optical scattering angle, and using photons weight change law to determine the photon annihilation. Respectively in the condition of a fixed seawater attenuation coefficient and attenuation coefficient changing with depth, this paper dynamically simulated the underwater optical slant path transmission of power attenuation and bit error rate, and analyzed the influence of the photons movement in power attenuation and bit error rate.
Research of ad hoc network based on SINCGARS network
Author(s):
Hao Nie;
Xiaoxia Cai;
Hong Chen;
Jian Chen;
Pengfei Weng
Show Abstract
In today's world, science and technology make a spurt of progress, so society has entered the era of information technology, network. Only the comprehensive use of electronic warfare and network warfare means can we maximize their access to information and maintain the information superiority. Combined with the specific combat mission and operational requirements, the research design and construction in accordance with the actual military which are Suitable for the future of information technology needs of the tactical Adhoc network, tactical internet, will greatly improve the operational efficiency of the command of the army. Through the study of the network of the U.S. military SINCGARS network, it can explore the routing protocol and mobile model, to provide a reference for the research of our army network.
Wideband and flexible microwave photonic satellite repeater systems for advanced space communication application
Author(s):
Jie Yin;
Tao Dong;
Hui Guo;
Zijing Cheng;
Guixing Cao;
Kun Xu
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To solve the satellite repeater’s flexible and wide-band frequency conversion problem, two novel microwave photonic repeater schemes of generating four and eight different output RF frequencies from one input RF carrier are proposed by adjusting the dual-parallel Mach-Zehnder Modulator’s(DPMZM) electrical configurations. Both schemes can realize simultaneous inter- and intra-band frequency conversion in one single structure and need only one onboard frequency-fixed microwave source. In the first scheme, one C-band RF signal’s 6 GHz carrier can be successfully converted to 2GHz, 4GHz, 16GHz and 22GHz, while the other scheme demonstrates the frequency conversion from 16GHz to eight different frequencies(6GHz, 26GHz, 22GHz, 42GHz, 4GHz, 36GHz, 12GHz and 52GHz).
Design and fabrication of deformable mirror driven by piezoelectric buzzer array
Author(s):
Lei Tian;
Zhengxiong Zhu;
Jialian Zhang;
Jianqiang Ma
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A low-cost deformable mirror (DM) driven by an underlying piezoelectric buzzer array though connection struts is proposed. Piezoelectric buzzer is a very low cost device that is easily commercial available. A numerical model of piezoelectric buzzer was built to predict the displacement of the actuator. The fabrication process without complicated technology was developed. Finally, a DM with 19 actuators arranged hexagonally was fabricated.
Modeling and optimizing of a water-cooled unimorph deformable mirror
Author(s):
Zhengxiong Zhu;
Lei Tian;
Jialian Zhang;
Jianqiang Ma
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A water-cooled unimorph deformable mirror (DM) is proposed for high-power laser applications. The piezoelectric actuators are distributed around the correction area on the front side of the DM. The cooling water flows through the back side of the DM. This design realizes the physical separation between the electrical connections and cooling medium. It is important to optimize the structure of the designed water-cooled DM. First, a model of the DM was established using finite element method (FEM) to predict the deformation behavior of single actuator and the reconstruction of the DM. Then the comparison analysis of different apertures, radii and thicknesses were performed for structure optimization. The simulation results indicate that: The reconstructing precision of the DM is better than 98% for the typical low-order aberrations with relative large amplitude under the voltage range from -50V to +50V, which is suitable for high-power laser beam shaping.
A novel delay-constraint routing algorithm in integrated space-ground communication networks
Author(s):
Xiaosong Yu;
Liu Yang;
Yuan Cao;
Yongli Zhao;
Xue Chen;
Jie Zhang;
Chunfeng Wang
Show Abstract
In recent years, the integrated space-ground network communication system plays an increasingly important role in earth observation and space information confrontation for the civilian and military service. Their characteristic on wide coverage, which may be the only way to provide Internet access and communication services in many areas, has extensively promoted its significance. This paper discusses the architecture of integrated space-ground communication networks, and introduces a novel routing algorithm named Improved Store-and-forward Routing Mechanism (ISRM) to shorten the transmission delay in such a network. The proposed ISRM algorithm is based on store and forward mechanism, while it trying to find several alternative delay-constraint paths by building the route-related nodes encounter-probability information table and communication timing diagram. Simulation is conducted at the end, and comparisons between ISRM and baseline algorithm are given. The results show that ISRM can achieve relatively good performance in terms of transmission latency in integrated space-ground networks.
Ad hoc Laser networks component technology for modular spacecraft
Author(s):
Xiujun Huang;
Dele Shi;
Zongfeng Ma;
Jingshi Shen
Show Abstract
Distributed reconfigurable satellite is a new kind of spacecraft system, which is based on a flexible platform of modularization and standardization. Based on the module data flow analysis of the spacecraft, this paper proposes a network component of ad hoc Laser networks architecture. Low speed control network with high speed load network of Microwave-Laser communication mode, no mesh network mode, to improve the flexibility of the network. Ad hoc Laser networks component technology was developed, and carried out the related performance testing and experiment. The results showed that ad hoc Laser networks components can meet the demand of future networking between the module of spacecraft.
Optical response and pulse shaped modulation of high power light emitting diodes
Author(s):
Zhujun Jia
Show Abstract
While light emitting diodes (LEDs) are used for general illumination, they are expected to find application in optical data transmission due to their fast optical response. In the present work, the optical response of the high power LEDs (3W) was examined in 4MHz pulse modulation. An optical pulse shaping strategy was devised by the stepped pulse drive with an overvoltage carrier injection and a proper extraction respectively in the pulse rising and falling time. The pulse driving and shaping circuit for the high power LED modulation was developed based on this strategy. The modulation bandwidth limitation was discussed in terms of the resistor-capacitor (RC) equivalent circuit. The light field of the LED chip surface under the injection-extraction pulse drive was observed to present different brightness around the electrode, resolving the carrier distribution in the transportation time. In disagreement with the RC explanation, the result shows that the optical response speed and bandwidth are limited by the lateral drift distance of the carriers between the electrode strips, especially for the high power LED with large chip size.
