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2013
Volume: 50 Issue 12
30 Article(s)
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Atmospheric Optics and Oceanic Optics
Multiframe Turbulence-Degraded Image Restoration Method Based on Temporal Signature
Shao Hui, Wang Jianye, Xu Peng, and Yang Minghan
In order to restore turbulence-degraded images exactly and rapidly, an iterative blind deconvolution (IBD) algorithm in the frequency domain based on temporal signature is proposed. The temporal signature regularization and Tichonov regularization are incorporated in the cost function. The constraints of non-negativityIn order to restore turbulence-degraded images exactly and rapidly, an iterative blind deconvolution (IBD) algorithm in the frequency domain based on temporal signature is proposed. The temporal signature regularization and Tichonov regularization are incorporated in the cost function. The constraints of non-negativity, energy and bandwidth of the PSFs are added in the iterative blind deconvolution to estimate the object image and point spread functions (PSFs) by the second order conjugation gradient (CG) optimization method. Structure-adaptive applicability filter is used to reduce noise and promote the edges of images. The experimental results show that the proposed algorithm is efficient to recover different intensity turbulence-degraded images and robust with high noise-resisting ability..
Laser & Optoelectronics Progress
- Publication Date: Nov. 18, 2013
- Vol. 50, Issue 12, 120101 (2013)
Retrieval of Sea Surface Salinity with MERIS in the Bohai Sea
Qing Song, Zhang Jie, and Bao Yuhai
Salinity is an important physical oceanographic parameter which influences many processes in the ocean. A multi-linear regression model and artificial neural network are developed for sea surface salinity and tested against in situ measurements in the Bohai Sea. The models are validated by in situ data. The root mean sSalinity is an important physical oceanographic parameter which influences many processes in the ocean. A multi-linear regression model and artificial neural network are developed for sea surface salinity and tested against in situ measurements in the Bohai Sea. The models are validated by in situ data. The root mean square errors are 0.858 psu and 0.689 psu (psu stands for practical salinity unit) with the correlation coefficients of R2=0.81 and R2=0.82, respectively. Then the model is applied to MERIS data to derive sea surface salinity map which can generally characterize the spatial pattern of sea surface salinity of the Bohai Sea. Both models are suitable for multi-spectral remote sensing data..
Laser & Optoelectronics Progress
- Publication Date: Nov. 08, 2013
- Vol. 50, Issue 12, 120102 (2013)
Image Processing
Ship Targets Detection of Ocean Surveillance Satellite Images Based on Visual Attention
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
An improved Itti′s model is applied on the ship targets detection of ocean surveillance satellite images. We illustrate the algorithm process of Itti′s model, and introduce a capacitor array charging model to describe the extracting and transferring process of the focus of attention. To solve the problems existing in tAn improved Itti′s model is applied on the ship targets detection of ocean surveillance satellite images. We illustrate the algorithm process of Itti′s model, and introduce a capacitor array charging model to describe the extracting and transferring process of the focus of attention. To solve the problems existing in the traditional Itti′s model such as the fixed shape and size of the extracted salient region, the poor real-time detecting performance when the radius of salient region goes too small, and excessive background areas contained in the salient region when the radius is set too large, the algorithm is improved in some aspects in this paper. Firstly, the discrete moment transform is introduced to the algorithm to enhance the response of image texture features. Then, the threshold segmentation method is chosen to extract the salient region with the focus of attention, and thus both the detection accuracy and real-time performance are improved greatly. According to the Matlab test results of the improved algorithm, it is verified that both the shape and size of the salient region are consistent well with the ship targets; the background contained in the salient region is also reduced significantly. Moreover, the improved algorithm has a good real-time performance. It comes to the conclusion that compared with Itti′s model, the improved algorithm is more effective and suitable for the extraction of ship targets detection of ocean satellite images..
Laser & Optoelectronics Progress
- Publication Date: Nov. 19, 2013
- Vol. 50, Issue 12, 121001 (2013)
TCM Spectral Imaging Detection Based on Self-Adaptive Region Segmentation Method
Wang Lin, Hu Cuiying, Pang Qichang, Ma Ji, and Cui Daijun
We use a segmentation arithmetic of self-adaption to deal with the spectral images of traditional Chinese medicine (TCM) obtained from TCM spectral detection. Through the motion detection, automatic selection of differential image and statistics of each spectral curve′s central-wavelength, the pixel points of TCM imageWe use a segmentation arithmetic of self-adaption to deal with the spectral images of traditional Chinese medicine (TCM) obtained from TCM spectral detection. Through the motion detection, automatic selection of differential image and statistics of each spectral curve′s central-wavelength, the pixel points of TCM image are classified and the spectral image of TCM is divided into different areas automatically. Then spectral information is extracted from different areas of TCM′s spectral image and the effect of background noise on experimental result is eliminated obviously. As an example, images of Coptis chinensis and its mixed powder are processd with this arithmetic. The experimental results indicate that this arithmetic can automatically pick up effective areas in a precise way. It can better eliminate the interference from noises and would not produce any useless area..
Laser & Optoelectronics Progress
- Publication Date: Nov. 07, 2013
- Vol. 50, Issue 12, 121002 (2013)
On Line Defect Detection Method for Lens Based on Machine Vision
Yao Hongbing, Zeng Xiangbo, Ma Guidian, Zheng Xueliang, Li Yaru, Gao Yuan, Yu Wenlong, Gu Jinan, and Jiang Guangping
An online machine vision defect detection method based on two-stage image acquisition structures is proposed for the online detection of the hard resin lenses. With the two-stage image acquisition structures, this method is able to increase the image processing speed by improving the image acquisition speed and reducinAn online machine vision defect detection method based on two-stage image acquisition structures is proposed for the online detection of the hard resin lenses. With the two-stage image acquisition structures, this method is able to increase the image processing speed by improving the image acquisition speed and reducing the image data amount. With the usage of image processing tools, the defects are rapidly identified according to the characteristics of filling degree and position, and the sizes of defects are determined based on the different measurement accuracies of the two-image acquisition stages. Then the lenses are classified according to the obtained identification and sizes. The experimental results show that this method can meet the requirement of online real-time detection for resin lenses and has a good classification result..
Laser & Optoelectronics Progress
- Publication Date: Nov. 08, 2013
- Vol. 50, Issue 12, 121003 (2013)
Imaging Systems
Comparative Research on Three Sub-Apertures and Three Arms Sparse Aperture Systems
Wang Youqing, Tan Zhijie, Fan Junliu, Jiang Hui, Chen Ying, Li Dan, He Xin, and Wu Quanying
Two kinds of sparse aperture systems of three sub-apertures and three arms sparse aperture are researched, and the characteristics of this two kinds of sparse aperture configurations are analyzed. Modulation transfer functions (MTFs) of the three sub-apertures and three arms configurations are derived from the formulasTwo kinds of sparse aperture systems of three sub-apertures and three arms sparse aperture are researched, and the characteristics of this two kinds of sparse aperture configurations are analyzed. Modulation transfer functions (MTFs) of the three sub-apertures and three arms configurations are derived from the formulas of the pupil functions．Based on the formulas of MTF, MTF curves are simulated by Matlab. Comparing the MTFs of three sub-apertures and the three arms aperture, it is shows that MTFs of two kind of configurations are all arranged to uniform hexagon. When the fill factors are both at 20%, the MTFs of three sub-apertures and three arms aperture have zero frequency at the normalized spatial frequencies of 0.3 and 0.15, respectively. The MTFs of the two sparse aperture configurations become larger with the increase of the fill factor. The MTF curve of three arms aperture is more stable than that of three sub-apertures, but with smaller MTF values. As a result, three arms apertures lose more information. The results of imaging simulation and image enhancement of two sparse aperture configurations show that three sub-apertures configuration outperforms three arms aperture in imaging quality..
Laser & Optoelectronics Progress
- Publication Date: Nov. 15, 2013
- Vol. 50, Issue 12, 121101 (2013)
Modulation Transfer Function Assessment of Spaceborne Linear Charge-Coupled Device Subpixel Imaging
Li Yapeng, and He Bin
In order to evaluate the modulation transfer function (MTF) of different subpixel imaging modes of spaceborne linear charge-coupled device (CCD), a quantitative assessment method based on MTF which can better characterize image quality is proposed. The MTF of subpixel imaging modes of linear CCD is derived. Compared wiIn order to evaluate the modulation transfer function (MTF) of different subpixel imaging modes of spaceborne linear charge-coupled device (CCD), a quantitative assessment method based on MTF which can better characterize image quality is proposed. The MTF of subpixel imaging modes of linear CCD is derived. Compared with conventional imaging mode by a single linear CCD, analysis shows that, theoretical limiting resolution values of 1/2, 1/3, 1/4 CCD-pixels staggered subpixel imaging modes by simultaneously using multiple uniform linear CCDs are improved by 86.2%, 88.78%, 89.54%, respectively, MTF values at normalized spatial frequency of 0.5 are increased by 0.1679 (41.43%), 0.2026 (49.99%), 0.2151 (53.07%) respectively, and modulation transfer function areas (MTFAs) in the normalized spatial frequency range of (0, 0.5) are enhanced by 10.09%, 12.08%, 12.77%, respectively. Simulation experiment on Matlab platform is performed. Gray mean gradient (GMG) and energy of Laplacian (EOL) are utilized to evaluate the image quality performance of three subpixel imaging modes objectively and the results demonstrate the validity of this method. The proposed method has some reference value to the design of linear CCD subpixel imaging system in remote sensing..
Laser & Optoelectronics Progress
- Publication Date: Nov. 15, 2013
- Vol. 50, Issue 12, 121102 (2013)
Localization of Facular Centroid Based on the Rectangular Quadrant Algorithm
Xu Zeshuai, Yang Yi, and Lan Weihua
Laser suffers wavefront distortion in atmospheric transmission. In order to detect the wavefront, we use the Hartmann-Shack (H-S) wavefront sensor to obtain the information of wavefront and locate the centroid of facula by the centroid algorithm. In this way, we can achieve wavefront detection. We put forward the algorLaser suffers wavefront distortion in atmospheric transmission. In order to detect the wavefront, we use the Hartmann-Shack (H-S) wavefront sensor to obtain the information of wavefront and locate the centroid of facula by the centroid algorithm. In this way, we can achieve wavefront detection. We put forward the algorithm of rectangular quadrant and obtain the location of centroid by experiment, thereby using the rectangle to enclose the facula. The rectangle can be divided into four parts by axes. The sum of gray values in each part can be determined. According to the geometrical relationship, different formulas are used to determine the centroid for rectangles at different positions. By comparison with the centroid algorithm, it is found that the positions of centroid derived from two algorithms are nearly the same and the speeds of two algorithms are also nearly equal..
Laser & Optoelectronics Progress
- Publication Date: Nov. 07, 2013
- Vol. 50, Issue 12, 121103 (2013)
Study on Automatic Test of the Assembly Structures Inside Products Based on X-Ray Stereoscopic Vision
Han Yueping, and Li Ruihong
It is still an unresolved issue to test the assembly structures inside products in industry applications. Spatial sampling criteria based on the single view imaging system are proposed for recognition of structural objects. There must be a maximum rotary step for an object within which the least structural size to be tIt is still an unresolved issue to test the assembly structures inside products in industry applications. Spatial sampling criteria based on the single view imaging system are proposed for recognition of structural objects. There must be a maximum rotary step for an object within which the least structural size to be tested is ascertained. Rotating the object by the step and imaging it and so on until a 360°turn is completed, an image sequence is obtained that includes the full structural information for recognition. The maximum rotary step is restricted by the least structural size and the resolution of the imaging system. Based on the spatial sampling criteria for structural recognition, the theory of fast recognition of structural objects is proposed. It is verified that objects could be fast recognized at a single or some limited orientations with a single camera by analyzing the smooth correlations among the image sequence sampled from 0° to 360° orientation. The theory is applied to the X-ray digital radiography system designed for online automatic inspection of interior assembly structures of complex products. Experiments show that the average identification takes less than 5 s in test progress at the wrong recognition rate of 4.5%..
Laser & Optoelectronics Progress
- Publication Date: Nov. 15, 2013
- Vol. 50, Issue 12, 121104 (2013)
Integrated Optics
Study on the Transmission Characteristics of Symmetric Hybrid Long-range Surface Plasmon Polariton Waveguide
Zhang Guanmao, Sun Haili, Li Jianming, and Zhao Hai
A novel symmetric hybrid long-range surface plasmon polariton waveguide structure is proposed and numerically analyzed. The results show that the proposed structure provides a better trade-off between the propagation length and mode confinement. The characteristics of the mode effective index, mode width, propagation lA novel symmetric hybrid long-range surface plasmon polariton waveguide structure is proposed and numerically analyzed. The results show that the proposed structure provides a better trade-off between the propagation length and mode confinement. The characteristics of the mode effective index, mode width, propagation length and figures of merit of the fundamental mode supported by this waveguide structure are calculated at the telecom wavelength 1550 nm for different dimensions of the polymer ridge and relatively low index dielectric regions (RLIDRs) under the metal. It is shown that the symmetric structure exhibits an increase in the propagation length, as well as a substantial increase in the figures of merit at the maximum point of the propagation length. For these advantages, the symmetric hybrid long-range surface plasmon polariton waveguide is a good candidate for realizing highly functional density photonic integration circuits..
Laser & Optoelectronics Progress
- Publication Date: Nov. 12, 2013
- Vol. 50, Issue 12, 121301 (2013)
Lasers and Laser Optics
Experimental and Mechanism Research on Paint Removal with Low Frequency YAG Pulsed Laser
Zhang Heng, Liu Weiwei, Dong Yazhou, Chen Junchao, and Zhang Hongchao
Laser cleaning technology, which is environment-friendly, has a wide range of application prospects in remanufacturing, micro-electro-mechanical system (MEMS) and ultra-precision machining. The mechanism and experimental research of removing paint layer from FV520B substrate with low frequency pulsed YAG laser is carriLaser cleaning technology, which is environment-friendly, has a wide range of application prospects in remanufacturing, micro-electro-mechanical system (MEMS) and ultra-precision machining. The mechanism and experimental research of removing paint layer from FV520B substrate with low frequency pulsed YAG laser is carried out. The experimental results show that, the removal mechanism differs under different experimental conditions, which is mainly ablation effect when blowing argon but transfers into vibration effect and ablation effect when water as a transparency overlay is used. The overlay water can not only increase the removal rate but also enlarge the damage threshold of laser. The removing effect of overlapping ratio is also calculated, that is, with the laser scanning speed of 249 mm/min and the overlap value between two traces of 0.6 mm, the whole paint layer can be removed completely with the removal rate of 15.5 mm2/s..
Laser & Optoelectronics Progress
- Publication Date: Nov. 04, 2013
- Vol. 50, Issue 12, 121401 (2013)
Influence of Process Parameters on Weldment Gap, Depth of Fusion and Lap-Shear Strength of PA66 with Laser Transmission Welding
Yan Zhang, Li Pin, Liu Huixia, Cai Ye, Chen Hao, Huang Chuang, Zhao Zhenguan, and Wang Xiao
The influence of clamp pressure on the gap, the depth of fusion and the lap-shear strength of weldments is studied based on PA66 thermoplastic materials reinforced with glass fiber and carbon fiber. The relation among the gap, the depth of fusion and the lap-shear strength is analyzed, from which the great importance oThe influence of clamp pressure on the gap, the depth of fusion and the lap-shear strength of weldments is studied based on PA66 thermoplastic materials reinforced with glass fiber and carbon fiber. The relation among the gap, the depth of fusion and the lap-shear strength is analyzed, from which the great importance of clamp pressure in the welding test can be seen. The effect of welding velocity and power on the depth of fusion and the lap-shear strength is then studied deeply. The connection between the depth of fusion and the lap-shear strength of weldments is obtained from a large number of experimental data and fitting curves. Finally, the influence of linear energy on the depth of fusion and the lap-shear strength of weldments is discussed. The results show that the process parameters affect the weldments gap and the depth of fusion, which results in the changes of the lap-shear strength. The study of the changes of the weldments gap and the depth of fusion can make it clear that how does the process parameters affect the lap-shear strength..
Laser & Optoelectronics Progress
- Publication Date: Nov. 19, 2013
- Vol. 50, Issue 12, 121402 (2013)
Simulation Research of Temperature Field and Electric Field in Laser Electrochemical Compound Processing
Yin Jie, Zhang Zhaoyang, Zeng Yongbin, Li Zhongyang, and Qin Changliang
Laser electrochemical compound etching, combining laser energy and electrochemical etching processing, removes the workpiece material by using the thermal-mechanical effect of laser and electrode reaction, and achieves the selective localized etching processing. For the multiple-field coupling characteristics of laser Laser electrochemical compound etching, combining laser energy and electrochemical etching processing, removes the workpiece material by using the thermal-mechanical effect of laser and electrode reaction, and achieves the selective localized etching processing. For the multiple-field coupling characteristics of laser electrochemical compound processing, the finite element analysis software ANSYS is used to perform finite element numerical simulation of transient temperature field and electric field of the compound etching target material. The influence of changes in the transient temperature field and electric field on the scope and depth of processing area is studied. By comparing the results with experimental ones, the laser electrochemical mechanism of material removal and etching forming is shown. The surface topography characteristic of the micro-machining process in laser electrochemical compound processing is discussed, which provides the guidance for the optimization of compound processing technology..
Laser & Optoelectronics Progress
- Publication Date: Nov. 19, 2013
- Vol. 50, Issue 12, 121403 (2013)
Self-Healing of Selectively Reflected Airy Beam from Resonant Atoms
Li Li, Zhao Xiaoxia, Zhu Junfan, Li Yuanyuan, Zhang Yiqi, Zhang Yanpeng, and Xu Kewei
Self-healing of selectively reflected (SR) Airy beam from cascade three-level atoms sandwiched between two dielectric walls is investigated. A theoretical model is developed to calculate SR Airy beam at an interface between dielectric and resonant atoms. Numerical simulation is also implemented, and the result shows thSelf-healing of selectively reflected (SR) Airy beam from cascade three-level atoms sandwiched between two dielectric walls is investigated. A theoretical model is developed to calculate SR Airy beam at an interface between dielectric and resonant atoms. Numerical simulation is also implemented, and the result shows that self-healed SR beams can be found both at normal and oblique incidence of the probe field, although there is a severe breakdown in the former case. We also show that the spectrum of the SR beams can be dramatically modified by the probe detuning and the coupling strength from the anisotropic behavior, enhancement and suppression of atomic radiation. The enhancement and the suppression are mainly from the interference and the alternating current (AC)-Stark splitting between dressed states created by the coupling field. These types of SR beams can have potential applications in the spatial detection and manipulation of resonant particles, as well as the optical storage and communication of information..
Laser & Optoelectronics Progress
- Publication Date: Nov. 12, 2013
- Vol. 50, Issue 12, 121404 (2013)
Theoretical Study on Propagation Properties of Semi-Gaussian Laser Beam
Guo Chaoxiu, Ling Chen, Du Xiangli, and Yin Yaling
Based on the Huygens-Fresnel diffraction integral theory, the propagating properties of semi-Gaussian laser beams in free space are theoretically calculated in detail. Analytical propagation equations are derived, which permit us to study the intensity distributions of two-dimensional (2D) semi-Gaussian laser beams proBased on the Huygens-Fresnel diffraction integral theory, the propagating properties of semi-Gaussian laser beams in free space are theoretically calculated in detail. Analytical propagation equations are derived, which permit us to study the intensity distributions of two-dimensional (2D) semi-Gaussian laser beams propagating in free space. The calculated results show that the propagation stability of semi-Gaussian laser beams in free space can be maintained well in the near field. As the propagation distance increases, the maximum intensities of the propagating laser beams decrease while the diffraction fringes gradually increase. At the same time, the width of the rising edge gradually grows. Finally semi-Gaussian laser beams become symmetrical beams. The better the symmetry is, the better propagation stability of semi-Gaussian laser beams will be..
Laser & Optoelectronics Progress
- Publication Date: Nov. 07, 2013
- Vol. 50, Issue 12, 121405 (2013)
Optical Design and Fabrication
Design of Rear-Focus Zoom Lens
Zhang Zhenzhou, Zhang Tingcheng, Zong Xiaoying, and Liao Zhibo
The principle and method of designing rear-focus type zoom lens are presented. The main ideas include optical power determination of each lens group, P, W parameters optimization based on system aberrations balance, and getting the initial real lens groups. By this method, a rear-focus continuous zoom lens, with focal The principle and method of designing rear-focus type zoom lens are presented. The main ideas include optical power determination of each lens group, P, W parameters optimization based on system aberrations balance, and getting the initial real lens groups. By this method, a rear-focus continuous zoom lens, with focal length of 5~50 mm, F-number of 1.6 and good image quality, is obtained. The effectiveness of the method is proved by this example..
Laser & Optoelectronics Progress
- Publication Date: Nov. 08, 2013
- Vol. 50, Issue 12, 122201 (2013)
Designand Simulation of Large-Scale Moon Simulator Optical System
Fu Ming, Zhang Guoyu, Zheng Ru, and Wang Guoming
The optical system of a large moon simulator with the diameter of 2500 mm is designed. By controlling the LED light of different bands and combining it into multiple group elements and lamp arrays, the simulation of the moon spectrum and the transition of different moon phase in the spectral bands from 355 nm to 1000 nThe optical system of a large moon simulator with the diameter of 2500 mm is designed. By controlling the LED light of different bands and combining it into multiple group elements and lamp arrays, the simulation of the moon spectrum and the transition of different moon phase in the spectral bands from 355 nm to 1000 nm is achieved. Thus the geometric characteristics and radiation characteristics of the particular “phase” are simulated. We introduce the composition and working principle of large moon simulator, and simulate and analyze the indicators including radiance and irradiation non-uniformity of different phases in the moon simulator by the LightTools software. The results show that the radiance is 32 W/(sr·m2) when the moon is full, the illumination non-uniformity is 14.7%, and the brightness non-uniformity is 17.2% on the luminous surface of different phases of the moon. These parameters can meet the design requirements..
Laser & Optoelectronics Progress
- Publication Date: Nov. 07, 2013
- Vol. 50, Issue 12, 122202 (2013)
Testing of Optical System Based on Point Light Source
Xu Jingwei, Yan Feng, and Zhang Xuejun
We introduce a simple method primarily developed for the performance evaluation of assembled space telescope in the field. The main idea of this method is to obtain the large parallel light beam for testing with an internal point light source and a plane mirror instead of large collimator. The wavefront error of the syWe introduce a simple method primarily developed for the performance evaluation of assembled space telescope in the field. The main idea of this method is to obtain the large parallel light beam for testing with an internal point light source and a plane mirror instead of large collimator. The wavefront error of the system can be calculated with phase diversity algorithm according to two images of the internal point source. The residual error and limitations of this method are discussed. A simulation is given at last, which shows the utilization potentiality of this approach..
Laser & Optoelectronics Progress
- Publication Date: Nov. 12, 2013
- Vol. 50, Issue 12, 122203 (2013)
Design of Refractive-Diffractive Night Vision System Based on Chalcogenide Glass
Lu Yajing, Song Baoan, Xu Tiefeng, Dai Shixun, Nie Qiuhua, Shen Xiang, Lin Changgui, and Zhang Peiqing
The illumination of cars is limited when they run at night or under other low visibility situations. The drivers have difficulty in seeing the scene and pedestrians in front, which greatly increases the risk of driving. Night vision system based on chalcogenide glasses is more and more used in automotive industry. The The illumination of cars is limited when they run at night or under other low visibility situations. The drivers have difficulty in seeing the scene and pedestrians in front, which greatly increases the risk of driving. Night vision system based on chalcogenide glasses is more and more used in automotive industry. The advantages and disadvantages of night vision systems are analyzed. A novel optical system based on chalcogenide glass and diffractive optical elements is presented. A diffractive-refractive hybrid night vision system with 30° field of view is designed. The effective focal length and F number are respectively 15 mm and 1. The system is composed of three lenses which use Ge20Sb15Se65, including a conic surface and a diffractive surface. The experimental results show that the modulation transfer function (MTF) of the hybrid system is close to diffraction limit at the spatial frequency of 15 lp/mm. The maximum focal shift is 6.6 μm in the range from -30 ℃ to 50 ℃, which is less than the system focal depth of 20 μm. The system has a compact structure and a good imaging quality..
Laser & Optoelectronics Progress
- Publication Date: Nov. 07, 2013
- Vol. 50, Issue 12, 122204 (2013)
Optical Devices
Focusing and Beam Splitting with Metal Waveguide Array
Hu Xueyao, Chen Yuegang, and Wu Cinan
Due to the difference in phase delay of light wave propagating through waveguides with different lengths, wave front can be modulated by waveguide array. Based on theoretical derivation, it is found that metal waveguide array with convex triangle in left and right sides can focus light wave. Using the finite-differenceDue to the difference in phase delay of light wave propagating through waveguides with different lengths, wave front can be modulated by waveguide array. Based on theoretical derivation, it is found that metal waveguide array with convex triangle in left and right sides can focus light wave. Using the finite-difference time-domain method, the focusing in metal waveguide array with convex triangle in left and right sides is simulated. It is found that when the thickness of waveguide h=6000 nm, the difference in waveguide length d=100 nm, the waveguide number m=10, and the waveguide width w=100 nm, the metal waveguide array has better focusing performance. Some valuable characteristics of such a structure are also found by investigating the of different framework parameters on its focusing properties. Simulations also indicate that when the waveguide width w2=80 nm, the central waveguide width w1=150 nm, the difference in waveguide length d=200 nm, the thickness of the waveguide h=4400 nm, and the waveguide number m=8, the concave triangular waveguide array can realize beam splitting..
Laser & Optoelectronics Progress
- Publication Date: Nov. 07, 2013
- Vol. 50, Issue 12, 122301 (2013)
Influence of Mirror Thermal Deformation on Beam Quality under Laser Long-Time Irradiation
He Minbo, Ren Weiyan, Zhang Shiqiang, Sun Yanhong, and Zhang Zheng
The temperature field and thermal deformation distributions of mirror under laser long-time irradiation are calculated and analyzed by using Comsol Multiphysics software. After presenting the wave aberration of mirror with the first 65 order Zernike polynomials, the beam quality factor β at different time is obtained. The temperature field and thermal deformation distributions of mirror under laser long-time irradiation are calculated and analyzed by using Comsol Multiphysics software. After presenting the wave aberration of mirror with the first 65 order Zernike polynomials, the beam quality factor β at different time is obtained. The results show that beam quality factor β is mainly composed of defocusing aberration, while other aberrations can be neglected. Then an exponential relationship between beam quality factor β and laser irradiation time is offered with the value 0.0052 of room-mean-square error..
Laser & Optoelectronics Progress
- Publication Date: Nov. 07, 2013
- Vol. 50, Issue 12, 122302 (2013)
OPTOELECTRONICS
Study of Field Emission Properties of Na Adsorption at Tips of Carbon Nanotubes
Fan Zhiqin, and Li Rui
We report a density functional theory (DFT) study regarding the effects of Na on field emission of single-wall carbon nanotubes (SWCNTs). Specifically, a comprehensive examination is carried out to investigate the effects of Na adsorbed on capped C(5,5) armchair SWCNT tips. A capped (5,5) carbon nanotubes model with diWe report a density functional theory (DFT) study regarding the effects of Na on field emission of single-wall carbon nanotubes (SWCNTs). Specifically, a comprehensive examination is carried out to investigate the effects of Na adsorbed on capped C(5,5) armchair SWCNT tips. A capped (5,5) carbon nanotubes model with different Na atoms adsorbed is built, and the adsorption energy, ionization potential, local density of states, Mulliken charge population of the model with and without the applied electric field are calculated and analyzed. The Mulliken charge population analysis shows that the charges are redistributed and accumulated on the tip. Under an applied electric field, the number of Mulliken charges that transfer from the carbon nanotube body to its tip increases with the increase of the number of Na atoms. The local density of states at the Fermi level increases with the adsorption of Na atoms. These results reveal that the field emission properties of carbon nanotubes can be enhanced by the adsorption of Na atoms..
Laser & Optoelectronics Progress
- Publication Date: Nov. 18, 2013
- Vol. 50, Issue 12, 122501 (2013)
Research of High Brightness and High Power Broad Area Semiconductor Lasers with Nitrogen-Hydrogen Passivation
Qiao Zhongliang, Zhang Jing, Lu Peng, Li Hui, Li Te, Li Lin, Gao Xin, Qu Yi, Liu Guojun, and Bo Baoxue
It is the most important core for high brightness high power semiconductor lasers to improve the resistance to catastrophic optical damage (COD) and output operation characteristic of broad area laser diodes (LDs). According to the sputter-reaction theory of passivation with nitrogen-hydrogen plasma, and using high theIt is the most important core for high brightness high power semiconductor lasers to improve the resistance to catastrophic optical damage (COD) and output operation characteristic of broad area laser diodes (LDs). According to the sputter-reaction theory of passivation with nitrogen-hydrogen plasma, and using high thermal heat-conduction AlxNy film to protect the passivated cavity, peak output power has increased by 66.7% for the new device. The aging speed of the LDs is less than 0.73% per 1000 h when they are working under continuum current operation with the output power of 3.5 W..
Laser & Optoelectronics Progress
- Publication Date: Nov. 08, 2013
- Vol. 50, Issue 12, 122502 (2013)
Physical Optics
Spectral Shifts and Spectral Switches of Polychromatic Spatially Coherent Light in Young′s Double-Circular-Aperture Interference Experiment in the Far Field
Wang Yun, Liu Yong, and Liu Dan
According to the Huygens-Fresnel principle in the paraxial domain, an expression for the spectrum of polychromatic spatially coherent light in Young′s double-circular-aperture interference experiment in the far field is derived, and detailed numerical calculations are performed. It is shown that the number of the spectAccording to the Huygens-Fresnel principle in the paraxial domain, an expression for the spectrum of polychromatic spatially coherent light in Young′s double-circular-aperture interference experiment in the far field is derived, and detailed numerical calculations are performed. It is shown that the number of the spectral switches on the oblique straight line with the y axis angle of 45° in the viewing screen is decreased with the increase of the central obstruction ratio of double-circular-aperture, and the distances among spectral switches on the line tend to be equal. With the increase of the central obstruction ratio, the distances among spectral switches at a fixed point on the straight line are shrunk. It is also shown that the spectrum on the x axis parallel to the double-circular-aperture center connection line is independent of the central obstruction ratio, and the distances among spectral switches are equal, changing the radius of the double-circular-aperture can control the number of spectral switches on the x axis. The spectral shifts and spectral switches on the y axis perpendicular to the center connection line depend on the location coordinates of the spatial points, the radius of the circular apertures and the central obstruction ratio of double-circular-aperture. With the increase of the central obstruction ratio of double-circular-aperture, the distances among spectral switches tend to be equal..
Laser & Optoelectronics Progress
- Publication Date: Nov. 04, 2013
- Vol. 50, Issue 12, 122601 (2013)
Reviews
Research Progress of Fabrication of Chalcogenide Glass Photonic Crystal Waveguide
Wang Xianwang, Zhang Wei, Zhang Liang, Li Junjian, and Xu Tiefeng
Photonic crystal is an artificial dielectric material whose dielectric constant changes periodically. It has two important features: photonic band gap and photon localization. Photonic crystal waveguide transmits light signal using photonic band gap. Compared with conventional strip waveguide, the most significant advaPhotonic crystal is an artificial dielectric material whose dielectric constant changes periodically. It has two important features: photonic band gap and photon localization. Photonic crystal waveguide transmits light signal using photonic band gap. Compared with conventional strip waveguide, the most significant advantage of photonic crystal waveguide is that there is very little transmission loss at the corner (the loss can be decreased to about 5% at the corner of 60°). Therefore, photonic crystal waveguide has important applications in the field of integrated optics. In this paper, we start with the features of chalcogenide glass, and introduce two types of methods in fabricating photonic crystal waveguides of chalcogenide glass. Through these two fabrication methods, photonic crystal waveguides can be obtained with both high quality of surfaces and low transmission loss. The differences between the two methods are also compared and the applications of the photonic crystal waveguide based on chalcogenide glass are introduced. Finally, the prospects of the photonic crystal waveguide based on chalcogenide glass are put forward..
Laser & Optoelectronics Progress
- Publication Date: Nov. 04, 2013
- Vol. 50, Issue 12, 120001 (2013)
Research Progress of Single Beam Femtosecond Laser Direct Writing Self-Organized Nanogratings in Fused Silica
Dai Ye, and Qiu Jianrong
Single beam femtosecond laser induced self-organized nanograting in fused silica has been a research focus in the field of femtosecond laser material processing since it was firstly characterized by electron microscope ten years ago. Here the formation of self-organized nanograting is briefly introduced, together with Single beam femtosecond laser induced self-organized nanograting in fused silica has been a research focus in the field of femtosecond laser material processing since it was firstly characterized by electron microscope ten years ago. Here the formation of self-organized nanograting is briefly introduced, together with its physicochemical properties, applications, and influencing factors. In addition, we point out the critical issues at present and suggest the potential research directions of this field as well..
Laser & Optoelectronics Progress
- Publication Date: Nov. 18, 2013
- Vol. 50, Issue 12, 120002 (2013)
Reviewof Laser Cladding Molten Pool Temperature Measurement and Control System
Hu Xiaodong, Yu Chengsong, and Yao Jianhua
Laser cladding is a new surface technology that has been developed rapidly in recent years. The performance of laser cladding layer is influenced by various factors, among which temperature of molten pool is a key factor in particular. The temperature measurement and control of laser cladding molten pool play an importLaser cladding is a new surface technology that has been developed rapidly in recent years. The performance of laser cladding layer is influenced by various factors, among which temperature of molten pool is a key factor in particular. The temperature measurement and control of laser cladding molten pool play an important role in controlling the quality of laser cladding. We introduce the commonly used temperature measurement methods, and review the current research state in various control systems for molten pool temperature of laser cladding. Based on the review, the future development of temperature measurement and control is prospected..
Laser & Optoelectronics Progress
- Publication Date: Nov. 08, 2013
- Vol. 50, Issue 12, 120003 (2013)
Research Progress of Optofluidic Flow Cytometry
Luo Dong, Lu Yuanfu, Jiao Guohua, Dong Yuming, Liu Peng, Chen Sihai, and Lü Jiancheng
Optofluidic technology is a new technology which combines optics and microfluidic technology to achieve cell counting and sorting of some species and other functions on the microchip. Miniaturization, lower prices and more compact structure of flow cytometry have been a trend with the vigorous development of optofluidiOptofluidic technology is a new technology which combines optics and microfluidic technology to achieve cell counting and sorting of some species and other functions on the microchip. Miniaturization, lower prices and more compact structure of flow cytometry have been a trend with the vigorous development of optofluidic technologies in recent years. It brings great convenience to health-care diagnostics, prevention and detection of certain diseases, that will improve the living standards of people. We introduce the lighting and detection optics, novel sorting equipment and other aspects of the latest developments in this field..
Laser & Optoelectronics Progress
- Publication Date: Nov. 19, 2013
- Vol. 50, Issue 12, 120004 (2013)
Spectroscopy
Calculation of Spectral Coefficientfor Molecules in High Temperature Gas
Zhao Yangsheng, and Du Xiaoping
In order to study spectral properties of high temperature gas around the surface of aircraft in hypersonic speed, we propose a practical calculation method of spectral coefficient for high temperature gas molecules. By calculating the energy level population of high temperature gas molecules in the studied area of the In order to study spectral properties of high temperature gas around the surface of aircraft in hypersonic speed, we propose a practical calculation method of spectral coefficient for high temperature gas molecules. By calculating the energy level population of high temperature gas molecules in the studied area of the aircraft, the broadening effect of spectral line is studied and the spectral parameter required is obtained based on the HITRAN database. Finally, the spectral radiation coefficient of the gas molecules is calculated by line-by-line method. The method can calculate the spectral coefficient of high temperature gas at corresponding wavelength effectively, and thus providing the important calculating parameters to analyze the aerodynamic flow field of hypersonic aircraft and the spectral radiation properties of the target. Furthermore, it can provide supporting data for the study of aircraft thermal protection and optical detection..
Laser & Optoelectronics Progress
- Publication Date: Nov. 15, 2013
- Vol. 50, Issue 12, 123001 (2013)
Research on the Method of Calibration of Cu in Soil by Single Pulse Laser-Induced Breakdown Spectroscopy
Li Wenhong, Wu Zhixiang, Wang Ruiwen, and Shang Liping
Calibration method has an important impact on the accuracy of quantitative analysis of laser-induced breakdown spectroscopy (LIBS). In the process of using LIBS to detect copper in soil samples, different calibration curves are used in order to do quantitative analysis, including exterior standard method and different Calibration method has an important impact on the accuracy of quantitative analysis of laser-induced breakdown spectroscopy (LIBS). In the process of using LIBS to detect copper in soil samples, different calibration curves are used in order to do quantitative analysis, including exterior standard method and different internal standard methods. Using Voigt fitting function to the spectral line at Cu 324.754 nm and Ca 317.9 nm to obtain the net intensity values, the net intensity ratio between Cu and Ca is then sought as internal standard to get calibration curve, which has the correlation coefficient up to 0.998. Through the cyclic inversion, the average relative error is 2.28% and the volatility is very small, so this method has good stability. Using the ratio between the spectra line intensity of Cu 324.754 nm and the area from 323 nm to 326 nm to establish the calibration curve, the correlation coefficient is 0.997 and the average relative error by cyclic inversion is 2.23%, but the stability is slightly lower than the former one. Directly using the Cu concentration and spectra line intensity to establish the calibration curve, the correlation coefficient is 0.972 and the average relative error by cyclic inversion is 13%, showing large fluctuations and less reliability..
Laser & Optoelectronics Progress
- Publication Date: Nov. 07, 2013
- Vol. 50, Issue 12, 123002 (2013)
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