Journals >Chinese Journal of Lasers
Contents
2013
Volume: 40 Issue 12
44 Article(s)
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Study on Resolution Limit of Total-Reflection X-Ray Optics with Heisenberg Uncertainty Principle
Sun Tianxi, Liu Zhiguo, Peng Song, Sun Weiyuan, and Ding Xunliang
Total-reflection X-ray optics play an important role in X-ray microscopy technology, and the study on their resolution limit is helpful for both designers and users. Theoretical study on the resolution limit of total-reflection X-ray optics is presented based on the Heisenberg uncertainty principle. The theoretical resTotal-reflection X-ray optics play an important role in X-ray microscopy technology, and the study on their resolution limit is helpful for both designers and users. Theoretical study on the resolution limit of total-reflection X-ray optics is presented based on the Heisenberg uncertainty principle. The theoretical results show that the resolution limit of total-reflection X-ray optics depends on material. The focal spot size limits of total-reflection X-ray optics made of nickel, lead glass and borosilicate glass are 3.2, 4.2 and 6.6 nm, respectively..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1217001 (2013)
Research Article
Drift Behavior of Airy Beams in Turbulence Simulated by Using a Liquid Crystal Spatial Light Modulator
Wang Xiaozhang, Li Qi, Zhong Wen, and Wang Qi
A method of superimposing multiple phase patterns in spatial light modulator to simulate the drift behavior of Airy beams in turbulence is proposed. Random phase screens which are generated by the Kolmogorov power spectrum model are superimposed with cubic phase patterns of Airy beams, and then a combined phase mask isA method of superimposing multiple phase patterns in spatial light modulator to simulate the drift behavior of Airy beams in turbulence is proposed. Random phase screens which are generated by the Kolmogorov power spectrum model are superimposed with cubic phase patterns of Airy beams, and then a combined phase mask is generated. The combined phase mask is loaded into the spatial light modulator to simulate Airy beams in turbulence. Through comparing the drifts of Airy beams and related Gaussian beams, it is found that the drift distances of Airy beams are less than that of related Gaussian beams. Therefore, Airy beams as information carriers have a good anti-jamming capability in remote transmissions..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1213001 (2013)
Analysis of Polarization Characteristics about Rough Surface Light Scattering Based on Polarized Bidirectional Reflectance Distribution Function
Gao Ming, Song Chong, and Gong Lei
To study the polarization characteristics about Gaussian rough surface light scattering, the Stokes vector of scattering light is derived based on microfacet theory and polarized bidirectional reflectance distribution function. The polarization characteristics of rough surface scattering light are numerically calculateTo study the polarization characteristics about Gaussian rough surface light scattering, the Stokes vector of scattering light is derived based on microfacet theory and polarized bidirectional reflectance distribution function. The polarization characteristics of rough surface scattering light are numerically calculated for both elliptically polarized light incidence and natural light incidence. The effects of incident angle, azimuth angle and complex refractive index on polarization characteristics of scattering light are studied. The result shows that the incident angle, the complex refractive index and the azimuth angle have a great influence on the ellipticity angle and the degree of polarization. The change trends of the degree of polarization curves and the ellipticity angle curves with different incident angles or complex refractive indexes have a high similarity. The change trends of the degree of polarization curves and the ellipticity angle curves with different azimuth angles have a large difference, but the two curves with complementary azimuth angles are symmetric about scattering angle θr=0. The maximum value of the ellipticity angle is obtained around the backscattering direction, and the minimum value of the degree of polarization is obtained in the backscattering direction..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1213002 (2013)
Research on the Characteristic of Clear-Day Dynamic turbulence in Troposphere Based on Wind Profile Radar
Zhang Caiyun, and Weng Ningquan
Wind profile radar is a new kind of instruments in remote sensing sounding, the echo signals of which contain abundant informations of turbulence. An algorithm for retrieval dynamic turbulence is proposed using the echo of wind profile radar, and the characteristic of velocity structure constant C2v in troposphere is aWind profile radar is a new kind of instruments in remote sensing sounding, the echo signals of which contain abundant informations of turbulence. An algorithm for retrieval dynamic turbulence is proposed using the echo of wind profile radar, and the characteristic of velocity structure constant C2v in troposphere is analyzed. Also, the turbulent velocity fluctuation in troposphere is discussed based on the velocity turbulence model. The results show that: 1) the strength of dynamic turbulence decreases along with the increase of the height, the lapse rate of which in the night is more rapid, and the C2v has remarkable diurnal variability at the top of boundary layer; 2) there is good linear relation between C2v and the natural logarithm of velocity fluctuation variance σ2, and the closeness of linear fitting could reach 0.896; 3) the velocity fluctuation of turbulence in troposphere is relatively small, and σ2 distributes between 10-3 m2·s-2 and 10-2 m2·s-2 in clear-air..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1213003 (2013)
Biomedical Photonics and Laser Medicine
An Optical Coherence Tomography Attenuation Compensation Algorithm Based on Adaptive Multi-Scale Retinex
Wang Longzhi, Yao Xiaotian, Meng Zhuo, Liu Tiegen, Li Zhihong, Shi Boya, Su Ya, Zhang Rongxiang, and Liu Wenhui
With imaging depth increasing, the local contrast in the optical coherence tomography (OCT) image of object decreases, which makes it difficult to observe the internal features of object. An adaptive multi-scale Retinex (AMSR) algorithm is proposed for OCT attenuation compensation. It automatically adjust the weights oWith imaging depth increasing, the local contrast in the optical coherence tomography (OCT) image of object decreases, which makes it difficult to observe the internal features of object. An adaptive multi-scale Retinex (AMSR) algorithm is proposed for OCT attenuation compensation. It automatically adjust the weights of Retinex enhanced images with different scales according to the mean values of absolute differences between Retinex enhanced image with large scale and Retinex enhanced images with other small scales. This method is verified by a human fingertip OCT image and skin OCT image that AMSR can effectively compensate the light attenuation in the original OCT image, and enhance the local contrast of structure details within object. Furthermore, comparing with the original OCT image, the visual contrast measure (VCM) of the AMSR enhanced image increases 5740. This method is useful to improve the visualization of structures inside object..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1204001 (2013)
Triglyceride Biosynthesis Induced by Low-Power Laser Irradiation via Regulation of ERK and Akt in Adipocytes
Jiang Xiaoxiao, Gong Longlong, and Huang Lei
Low-power laser irradiation (LPLI) can promote cell proliferation, migration and differentiation through activation of multiple signaling pathways. However, it is unclear whether LPLI can promote triglyceride biosynthesis in adipocytes via regulation of extracellular signal-regulated kinase (ERK) and protein kinase B (Low-power laser irradiation (LPLI) can promote cell proliferation, migration and differentiation through activation of multiple signaling pathways. However, it is unclear whether LPLI can promote triglyceride biosynthesis in adipocytes via regulation of extracellular signal-regulated kinase (ERK) and protein kinase B (PKB, also named Akt). In the present study, the changes of the ERK and Akt activity in 3T3-L1 pre-adipocytes and mature adipocytes upon LPLI stimulations is investigated using western blot analysis. The findings indicate that the activity of ERK and Akt is significantly elevated in 3T3-L1 pre-adipocytes under LPLI treatment. In contrast, the activity of ERK is dramatically reduced in mature adipocytes, but the activity of Akt is significantly elevated under LPLI treatment, suggesting that LPLI can differentially regulate the activity of ERK and Akt. Furthermore, the concentration of triglyceride in insulin resistant adipocytes is increased which is induced by LPLI through inhibition of ERK and activation of Akt. These results imply that LPLI can improve lipid metabolic disorders-induced insulin resistance through regulation of ERK and Akt..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1204002 (2013)
Multispectral Fluorescence Microscopic Imaging Based on Compressive Sensing
Wang Jincheng, Kuang Cuifang, Wang Yifan, and Liu Xu
Compressive sensing (CS) theory is used in fluorescence microscopy imaging and a new microscopic imaging system is designed and implemented. A liquid crystal light valve is employed to calculate the linear projection of an image onto pseudorandom patterns. Fluorescence is collected on a point detector. Images of the saCompressive sensing (CS) theory is used in fluorescence microscopy imaging and a new microscopic imaging system is designed and implemented. A liquid crystal light valve is employed to calculate the linear projection of an image onto pseudorandom patterns. Fluorescence is collected on a point detector. Images of the samples are acquired combined with the reconstruction theory of CS. The number of samples is smaller than that imposed by the Nyquist-Shannon theorem. The system hardware is simple as scanning is unnecessary during the imaging process. Compared with the traditional spectral imaging modalities, such as using optical filter and raster scanning, this system only needs a spectrometer to acquire signal and then multispectral images are reconstructed from measurements corresponding to a set of sub-bands. As the fluorescence microscopy imaging suffers fluorescence decay during imaging process, in this experiment, data preprocessing such as intensity normalization is applied and the results indicate that the influence of fluorescence decay on reconstruction is eliminated effectively with this processing method..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1204003 (2013)
Holography and Information Processing
Self-Calibration Phase-Shifting Digital Holographic Microscopy Based on Carrier Frequency Analysis
Xu Zhennan, and Zhong Jingang
Small phase shift errors in phase-shifting digital holographic microscopy can cause distinct errors in wave-front reconstruction. Phase shift errors generally fall into two categories: numerical errors and uneven errors. A considerable numerical error results from miscalibration of phase shifter and ambient vibrations.Small phase shift errors in phase-shifting digital holographic microscopy can cause distinct errors in wave-front reconstruction. Phase shift errors generally fall into two categories: numerical errors and uneven errors. A considerable numerical error results from miscalibration of phase shifter and ambient vibrations. Therefore, self-calibration phase-shifting scheme is worth trying. Here, a carrier frequency analysis based self-calibration phase-shifting digital holographic microscopy (PSDHM) is proposed. The actual phase shifts are calculated from Fourier analysis of holograms. The uneven errors are caused by irrational configuration of interferometer. We propose an improved Linik interferometer based setup of phase-shifting digital holography. The experimental results certify that both the self-calibration phase-shifting scheme and the proposed experimental setup have a better reconstruction quality..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1209001 (2013)
Infrared Image Dynamic Range Compression and Contrast Enhancement Based on Optimal Mapping Curve
Wu Zepeng, Xuan Ming, Jia Hongguang, Zhu Mingchao, Guo Lingling, and Liu Hui
Aiming at the drawback of conventional algorithms to compress dynamic range and enhance infrared images, which cannot preserve sufficient information of the original image, a new method based on the optimal mapping curve is proposed. The histogram of the original infrared image is convolved with an adaptive Gaussian keAiming at the drawback of conventional algorithms to compress dynamic range and enhance infrared images, which cannot preserve sufficient information of the original image, a new method based on the optimal mapping curve is proposed. The histogram of the original infrared image is convolved with an adaptive Gaussian kernel. Then, the first derivative of the smoothed histogram is utilized to accomplish segmentation of the original image. The segmented image is calculated to obtain an optimal nonlinear mapping curve, and then the enhanced image with low dynamic range is obtained. The experiment based on a large amount of infrared images is carried out and the processing results are evaluated qualitatively and quantitatively. The experimental results show that compared with the existing method, the proposed method can minimize the mean square error of the enhanced image compared with its origin. Meanwhile, it can significantly improve the overall visual effect of the image. This algorithm is fast, highly automotive and suitable for real-time processing of infrared videos..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1209002 (2013)
Laser Manufacturing
Microstructure-Property of Laser Cladding High Carbon Fe-Based Alloy
Zhou Yefei, Gao Shiyou, and Wang Jingjing
High carbon Fe-based alloy with various C contents is deposited by laser cladding technology. Optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) with energy dispersive spectrometer (EDS), microhardness tester and electrochemical workstation are used to investigate the microstructure, pHigh carbon Fe-based alloy with various C contents is deposited by laser cladding technology. Optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) with energy dispersive spectrometer (EDS), microhardness tester and electrochemical workstation are used to investigate the microstructure, phase, carbide morphology and composition distribution, microhardness and corrosion resistance of the cladding. The results show that the microstructure of high carbon Fe-based alloy is uniformed and compacted. With 2.5% C (mass fraction) in the cladding, the microstructure consists of primary γ-Fe with columnar dendrite morphology and inter-dendrite M7C3 carbide. With 4.5% C in the cladding, the microstructure consists of primary M7C3 carbide with equiaxed dendrite morphology and eutectic (M7C3+γ-Fe). With the content of C increasing, the average microhardness of the cladding increases from 913.96 HV to 1421.54 HV. Meanwhile, the corrosion resistance of the cladding is improved..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1203001 (2013)
Influence of Different Shapes on the Mechanical Properties of Laser Spot Weld of TC4 Titanium Alloy
Lv Tao, Lei Zhenglong, Chen Yanbin, Li Ying, and Hu Peipei
Four different shapes of weld are designed to execute the experiment of non-penetration welding of TC4 titanium alloy. Shear performance and fracture behavior of different welds are mainly researched. The shear performance has a relationship with the area of fusion surface. The double row of stitch weld has the highestFour different shapes of weld are designed to execute the experiment of non-penetration welding of TC4 titanium alloy. Shear performance and fracture behavior of different welds are mainly researched. The shear performance has a relationship with the area of fusion surface. The double row of stitch weld has the highest shear performance. The weld will depart from the interface or break along the cross-section at the endpoints. The existence of the residual stress leads the stress concentrating at the endpoints and subsequently descends the static performance of C weld with respect to double row of stitch weld..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1203002 (2013)
Research on the Properties of Laser Transmission Welding of Transparent-Transparent Polypropylene
Tan Yun, Zhu Yunlu, and Wang Chunming
Transparent-transparent plastic laser transmission welding is one of the toughest difficulties in the field of plastic laser welding. The key to solve this problem is to use the right absorber. The laser welding of transparent-transparent polypropylene technology is studied by using three kinds of absorbers: the carbonTransparent-transparent plastic laser transmission welding is one of the toughest difficulties in the field of plastic laser welding. The key to solve this problem is to use the right absorber. The laser welding of transparent-transparent polypropylene technology is studied by using three kinds of absorbers: the carbon, the black polypropylene particles and the black paint. Welds with desirable property are obtained when using black paint as the absorber. The research also investigates the influence of welding parameters (laser power, welding speed, the thickness of sample and thickness of black paint layer) on the welding quality. It turns out that the appearances of welding defects, such as porosities, thermal deformation holes and surface combustions, are related to low purity of raw materials and excessive energy input. These defects can be taken into control by using proper welding parameters and argon gas..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1203003 (2013)
Microstructure and Properties of Laser Cladding MoSi2 Composite Coating
Yang Jiaoxi, Wang Zhicheng, Wang Xin, and Hu Xing
Single MoSi2 cladding is prepared by CO2 laser with a spot diameter of about 3 mm. The main phase of long dendrite in the cladding layer is (Fe,Si)2Mo, as revealed by X-ray diffraction (XRD) and scanning electron microscope (SEM) detection. The interdendritic phase is mainly α-Fe and Fe2Si. Micro-hardness of the coatinSingle MoSi2 cladding is prepared by CO2 laser with a spot diameter of about 3 mm. The main phase of long dendrite in the cladding layer is (Fe,Si)2Mo, as revealed by X-ray diffraction (XRD) and scanning electron microscope (SEM) detection. The interdendritic phase is mainly α-Fe and Fe2Si. Micro-hardness of the coating is maintained at about 700 HV. The spot is shaped to a rectangle with the size of 2 mm×6 mm, and the cladding of Ni/MoSi2 mixed powder is then performed. It is found that as the Ni-based alloy increases, the cracks are significantly reduced, and the critical mass ratio of Ni and MoSi2 is 37. By calculating thermal stress and dilution ratio, it is proved that broadband laser cladding can be appropriate to reduce the thermal tensile stress and dilution rate. Finally, XRD and energy dispersive spectrometry (EDS) are used to detect the Ni/MoSi2 cladding and the main phases of high Mo dendrite are found to be MoSi2 and NiMo. The average micro-hardness is 750 HV and the maximum microhardness is 861.9 HV, present in the dendrite of coating, achieving the purpose of improving substrate physical properties..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1203004 (2013)
Composition and Properties Continuously Changed Gradient Coating Fabricated by High Power Diode Laser
Wu Qiang, Wang Xubao, Niu Jianqiang, Yang Wuxiong, Xiao Rongshi, and Zuo Tiechuan
To obtain gradient coating with changed components and properties, the gradient coating comprised of two-kind metal powders (Ni25/Ni60 and AlSi12/Fe62) is fabricated with paraxonic synchronism powder feeding mode, 2.5 kW high power diode laser and 4 channels powder system. The 9-mm width spiral gradient coatings on 45#To obtain gradient coating with changed components and properties, the gradient coating comprised of two-kind metal powders (Ni25/Ni60 and AlSi12/Fe62) is fabricated with paraxonic synchronism powder feeding mode, 2.5 kW high power diode laser and 4 channels powder system. The 9-mm width spiral gradient coatings on 45# steel stick are achieved. Meanwhile, energy dispersive spectroscopy (EDS), microstructure and micro-hardness of coating are studied. The experimental results show that along the forming direction, the content of element Cr and the micro-hardness decrease continuously in Ni25/Ni60 gradient coating; the contents of elements Fe, Cr and Al change continuously in AlSi12/Fe62 gradient coating; the microstructures in both coatings change obviously..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1203005 (2013)
Shaping Control of Welds for Fiber Laser Welding T-Section of Fuselage Panels
Zhang Yunlong, Tao Wang, Chen Yanbin, Chen Jie, Liu Hongbing, and Jiang Meng
Double-sided fiber laser beam welding is used to synchronously weld T-section of fuselage panels (skins and stringers) for aluminum-lithium alloy 2060/2099 and shaping control is analyzed as well as long transverse (LT) tensile performance. The results indicate that a good fusion between skins and stringers can be obtaDouble-sided fiber laser beam welding is used to synchronously weld T-section of fuselage panels (skins and stringers) for aluminum-lithium alloy 2060/2099 and shaping control is analyzed as well as long transverse (LT) tensile performance. The results indicate that a good fusion between skins and stringers can be obtained by using incident beam angle as small as possible in an adjustable range. The LT tensile strength reaches the maximum when the incident beam position is 0.1 mm on the stringer yielding a 45°~50° weld beam angle. To ensure weld microstructure uniformity and improve the T-joints′ mechanical properties, beam separation distance must be strictly controlled to achieve the fusion of the double-sided welds in a common molten. In order to realize smooth transition of the weld surface, the ratio of wire feeding speed to welding speed should be matched with a reasonable value. For welds with a fully fusion and uniform microstructure, the key factor restricting the LT tensile strength is weld penetration. The average LT tensile strength reaches 80.1% of that of the base materials and the maximum rises up to 82.1%, when weld penetration is controlled in 1 mm..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1203006 (2013)
Three-Dimensional Numerical Simulation of Transient Temperature Field and Coating Geometry in Powder Feeding Laser Cladding
Liu Hao, Yu Gang, He Xiuli, Li Shaoxia, Zheng Caiyun, Ning Weijian, and Ge Zhifu
A three-dimensional numerical model based on the birth-death element method is developed on the basis of characteristics of powder feeding laser cladding. The model, which takes the laser power attenuation by the powder stream and the heating of powder particles in the powder feeding process into account, has the capabA three-dimensional numerical model based on the birth-death element method is developed on the basis of characteristics of powder feeding laser cladding. The model, which takes the laser power attenuation by the powder stream and the heating of powder particles in the powder feeding process into account, has the capability of predicting the transient thermal field and coating geometry. Temperature distribution and geometric characteristic of coating during laser cladding process are investigated. The results show that the temperature field and coating geometry keep stable after a short initial stage of the process. Experiments with different powder feeding rates are performed to validate the calculated results. The calculated coating width, height and depth, as well as outline of coating, agree with the experimental ones, so the reliability of the model is proved..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1203007 (2013)
Effects of B4C and Ti Contents on Structure and Property of Laser Cladding Fe-Cr-Ni-Si Alloy Coatings
Li Meiyan, Han Bin, Wang Yong, Song Lixin, Guo Lanyang, and Yu Mengfei
The Fe-based coatings with different compositions are produced on 45# steel by laser cladding technology, and the structure and property are analyzed. The results show that the cross section is composed of cladding coating, heat affected zone and the matrix after laser treatment, and the interface between cladding coatThe Fe-based coatings with different compositions are produced on 45# steel by laser cladding technology, and the structure and property are analyzed. The results show that the cross section is composed of cladding coating, heat affected zone and the matrix after laser treatment, and the interface between cladding coating and the matrix is metallurgical bonding. The laser cladding coating is composed of columnar crystal, a little columnar crystal and fine dendrite, fine dendrite and carbides of type M23C6 from the bottom to surface. X-ray diffration results show that the content of austenite decreases and the content of martensite increases with the increment of B4C and Ti, while the microhardness and corrosion resistance are improved. However, when the Ti content reaches 4.5%, the structure changes obviously. Which is composed of a little cellular dendrite, fine dendrite and dendrite with plum blossom shape from the bottom to surface, and the hardness and corrosion resistance are best..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1203008 (2013)
Propagation Characteristic of Ultrasonic in BT20 Titanium Alloy and Research on Distribution of Ultrasonic Field in Molten Pool of Laser Deposition Repair
Yang Guang, Guo Pengfei, Wang Wei, Qin Lanyun, Bian Hongyou, Wang Wei, and Xiang Kun
The propagation characteristic of ultrasonic in repaired components of BT20 titanium alloy and molten pool is investigated by using ANSYS finite element simulation and experimental test. Under the circumstance that the horn vibrates longitudinally, the results show that when the length of repaired component coupled witThe propagation characteristic of ultrasonic in repaired components of BT20 titanium alloy and molten pool is investigated by using ANSYS finite element simulation and experimental test. Under the circumstance that the horn vibrates longitudinally, the results show that when the length of repaired component coupled with horn is less than 23% of the longitudinal wavelength, the type of ultrasonic vibration on the surface of repaired component belongs to longitudinal vibration; however, when the length of repaired component is more than 28% of longitudinal wavelength, the type of ultrasonic vibration belongs to bending vibration; With the length of repaired component increasing, resonant frequency changes a lot and redistributes when the length of repaired component is between 23% and 28% of the longitudinal wavelength. In the two different kinds of vibrations, as the length of repaired component increases, the resonant frequency declines. When ultrasonic vibration is loaded at a frequency of 19.56 kHz, with amplitude of 0.2 μm, the positive and negative acoustic pressure in the molten pool changes alternatively and the negative pressure reaches hundreds of thousands of pascals..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1203009 (2013)
Study on Scribing of Sapphire Substrate by Pulsed Green Laser Irradiation
Xie Xiaozhu, Huang Xiandong, Chen Weifang, Wei Xin, Hu Wei, and Che Ronghong
A pulsed green laser with wavelength of 532 nm is employed to scribe the sapphire substrate. Firstly, sapphire surface ablated by single pulsed laser is observed. The ablation threshold and the cracks threshold of sapphire are identified. The relationship between the laser fluence and crater depth/diameter is analyzed.A pulsed green laser with wavelength of 532 nm is employed to scribe the sapphire substrate. Firstly, sapphire surface ablated by single pulsed laser is observed. The ablation threshold and the cracks threshold of sapphire are identified. The relationship between the laser fluence and crater depth/diameter is analyzed. Then, the thermal stress of nanosecond green laser irradiating sapphire is analyzed. Finally, the parametric laser scribing of sapphire substrate is conducted. The results show that the formation of the craters and grooves in the laser ablation process is mainly due to the photothermal effect. The effect results in melting, vaporization, which is essential to the material removal. Meanwhile, micro-cracks are easily induced by the larger thermal stress. A narrow groove width of 20 μm, aspect ratio of 7 and better processing quality can be obtained simultaneously by considering laser processing parameters (laser fluence, scanning velocity and scanning times) and the treatment of the material surface..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1203010 (2013)
Laser Physics
Monolithically Integrated 10-Channel Multi-Wavelength Light Sources
Zhang Can, Zhu Hongliang, Liang Song, Han Liangshun, and Wang Wei
A monolithic integration of ten distributed feedback lasers with a 10×1 multimode-interference optical combiner using the selective area growth technology is proposed and demonstrated. In the device, Titanium film thermal resistance for wavelength tuning are integrated with a novel procedure. The device is mountedA monolithic integration of ten distributed feedback lasers with a 10×1 multimode-interference optical combiner using the selective area growth technology is proposed and demonstrated. In the device, Titanium film thermal resistance for wavelength tuning are integrated with a novel procedure. The device is mounted on heat sink and tested at 20 ℃. The average channel spacing of the device is 1.29 nm. The average output power of lasers is 0.5 mW with a current of 200 mA and threshold currents of 25~30 mA. The tuning efficiency of integrated thermal resistance is about 5 nm/W. The integrated device can cover 34 channels on the 50 GHz ITU (international telecommunication union) grid with a suitable heating power, which can operate separately or simultaneously..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1202001 (2013)
Blue Laser Diode Pumped Pr3+:YLF Visible Lasers
Wang Fengjuan, Liu Zhe, Xu Bin, Zeng Chenghang, Huang Shunlin, Yan Yu, Luo Saiyu, Cai Zhiping, and Xu Huiying
Red (640 nm) and green (522 nm) lasers with Pr3+:YLF pumped by a blue laser diode emitting at about 444 nm in the longitudinal direction are reported. On the basis of the beam reshaping of the pump spot by a prism, the maximum output power, absorbed threshold pump power and slope efficiency of the red laser are 308.5 mRed (640 nm) and green (522 nm) lasers with Pr3+:YLF pumped by a blue laser diode emitting at about 444 nm in the longitudinal direction are reported. On the basis of the beam reshaping of the pump spot by a prism, the maximum output power, absorbed threshold pump power and slope efficiency of the red laser are 308.5 mW, 46 mW and 47.5%, respectively. The three corresponding parameter values for green laser are 193.4 mW, 162.3 mW and 37.1%, respectively. The results show that the shaped pump beam is beneficial to improve the output characteristics of these two visible laser emissions..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1202002 (2013)
Low-Repetition High-Peak-Power Sub-Nanosecond Pulsed Yb-Doped Fiber Laser
Shi Hongxing, Liu Jiang, Sun Ruoyu, Tan Fangzhou, and Wang Pu
In this article, we report an efficient sub-nanosecond pulses generation in Yb-doped fiber laser with 400 kHz repetition rate and 960 ps pulse width, which adopts master oscillator fiber power amplifier (MOPA) configuration, extracting 8.9 W average output power up to 23 kW with central wavelength of 1064.5 nm. The seeIn this article, we report an efficient sub-nanosecond pulses generation in Yb-doped fiber laser with 400 kHz repetition rate and 960 ps pulse width, which adopts master oscillator fiber power amplifier (MOPA) configuration, extracting 8.9 W average output power up to 23 kW with central wavelength of 1064.5 nm. The seed laser with 100 mW average output power is amplified to 8.9 W by one-stage Yb-doped double-cladding fiber amplifier, pumped by 6 multimode laser diodes with maximum output power of 10 W. This kind of high-energy sub-nanosecond Yb-doped fiber laser can be widely used in material processing, laser radar, laser ranging and other fields..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1202003 (2013)
Optical Performance of High Power Laser Diode Stack
Zhou Minchao, Jiang Xianfeng, Zhang Lifang, and Sun Boshu
With the advantages of high efficiency, high power, long lifetime, etc., laser diode is the best option for pumping of solid state lasers. As for the pumping, good optical performances which include beam divergence and pointing of laser diode are required. Because the divergence of laser diode bar at fast axis is very With the advantages of high efficiency, high power, long lifetime, etc., laser diode is the best option for pumping of solid state lasers. As for the pumping, good optical performances which include beam divergence and pointing of laser diode are required. Because the divergence of laser diode bar at fast axis is very large, it is a hard work to collimate the beam and control the pointing of a bar, even harder to build a stack with good optical performance. Method of controlling beam quality of laser diode bar is studied, and a laser diode stack with 60 fast axis collimated bars is build up, the peak power of the stack is 18 kW, the total divergence (on fast axis) of the stack is less then 0.2° (3.5 mard), the pointing of each bar is within ±0.15° (±2.6 mrad)..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1202004 (2013)
Chaos Synchronization and Communication in Mesh Network Based on Mutually Coupled Semiconductor Lasers
Pan Xingmao, Wu Zhengmao, Tang Xi, and Xia Guangqiong
A chaotic mesh network system composed of four mutually coupled semiconductor lasers (SLs) is presented in this paper. For this system, the dynamical behaviors of each SL, the synchronization characteristics between arbitrary two SLs and the influence of parameter mismatches on the synchronization are investigated numeA chaotic mesh network system composed of four mutually coupled semiconductor lasers (SLs) is presented in this paper. For this system, the dynamical behaviors of each SL, the synchronization characteristics between arbitrary two SLs and the influence of parameter mismatches on the synchronization are investigated numerically, and the secure communication performance of such a system is analyzed. The theoretical simulation results show that all outputs from SLs in this mesh network system can route into chaos under suitable coupling condition, and global synchronization or partial synchronization can be observed for these four SLs. Based on chaos synchronization in this system, the bidirectional secure communication among multi-users can be achieved..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1202005 (2013)
High-Power Passively Q-Switched Nanosecond-Pulsed Thulium-Doped Fiber Laser
Liu Jiang, and Wang Pu
A high power all-fiber nanosecond-pulsed thulium-doped fiber master oscillator power amplifier (MOPA) system that consists of low power passively Q-switched thulium-doped fiber laser seed and two-stage thulium-doped double-clad all-fiber amplifiers pumped by high power multimode diodes at 790 nm is studied. The repetitA high power all-fiber nanosecond-pulsed thulium-doped fiber master oscillator power amplifier (MOPA) system that consists of low power passively Q-switched thulium-doped fiber laser seed and two-stage thulium-doped double-clad all-fiber amplifiers pumped by high power multimode diodes at 790 nm is studied. The repetition rate of the thulium-doped fiber laser seeder is tunable from 77 kHz to 240 kHz with the increase of pump power, the minimum pulse width is measured to be 250 ns and the maximum average output power is 73 mW. Two-stage double-clad thulium-doped all-fiber amplifiers are used to boost average power to 20 W, corresponding to single pulse energy of 100 μJ. The pulse width is 270 ns, and laser center wavelength is 1966 nm..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1202006 (2013)
Wavelength Tunable Yb-Doped Double-Clad Dissipative Soliton Fiber Laser
Zhang Liqiang, Zhuo Zhuang, Pan Zhiyong, Wang Yunzheng, and Wang Jingxuan
A wavelength tunable, passively mode-locked Yb-doped double-clad fiber laser with a birefringent filter is demonstrated in this paper. By carefully rotating the filter, the central wavelength of the mode-locked fiber laser can be continuously tuned from 1063.9 nm to 1091.1 nm. The pulse duration ranges from 13.9 ps to A wavelength tunable, passively mode-locked Yb-doped double-clad fiber laser with a birefringent filter is demonstrated in this paper. By carefully rotating the filter, the central wavelength of the mode-locked fiber laser can be continuously tuned from 1063.9 nm to 1091.1 nm. The pulse duration ranges from 13.9 ps to 16.8 ps, and spectrum width varies between 15.8 nm and 18 nm. The maximum average output power of 212 mW is obtained at the central wavelength of 1063.9 nm. The corresponding pulse energy is 8.5 nJ. A theoretical model is established based on the coupled Ginzburg-Landau equations and Jones matrices. Simulation results agree with the experimental results..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1202007 (2013)
Widely Tunable Mid-Infrared Difference Frequency Generation in a Temperature-Gradient-Controlled PPLN
Chang Jianhua, Huang Qin, Gu Jiuyu, Wang Yawei, and Yin Jie
A novel scheme for broadband mid-infrared (mid-IR) difference frequency generation (DFG) based on a temperature-gradient-controlled equal periodic PPLN is proposed. The theoretical results show that, under condition of the fixed pump wavelength, the acceptance bandwitdth (BW) of idler/signal quasi-phase matching (QPM) A novel scheme for broadband mid-infrared (mid-IR) difference frequency generation (DFG) based on a temperature-gradient-controlled equal periodic PPLN is proposed. The theoretical results show that, under condition of the fixed pump wavelength, the acceptance bandwitdth (BW) of idler/signal quasi-phase matching (QPM) is increased with the temperature gradient across the crystal, whereas the conversion efficiency decreases. When the pump wavelength is 1.08 μm, the idler QPM BW is about 8 nm in the uniform temperature case. However, when the initial end temperature is 30 ℃, and the crystal temperature gradient increases to 20 ℃, 40 ℃ and 60 ℃, the idler QPM BWs are broadened to 35 nm, 80 nm and 136 nm, and the relative conversion efficiencies decrease to 0.2, 0.095 and 0.06. When the temperature at the initial crystal end and the temperature gradient are 90 ℃ and 60 ℃, respectively, the broadband idler QPM band moves to the shorter wavelengths and could cover the range of 3.288~3.464 μm..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1202008 (2013)
Materials and Thin Films
Study on the Effect of Refractive Index and Metal Film Thickness on Surface Plasmon Resonance Field Enhanced Surface-Enhanced Raman Scattering
Liu Yu, Zhang Haitao, Xu Shuping, and Xu Weiqing
The effects of dielectric refractive index, prism refractive index and metal film thickness on the surface plasmon resonance (SPR) field enhanced surface-enhanced Raman scattering (SERS) with Kretschmann SPR configuration are studied. Experimental results show that SPR and SERS are essentially correlative. The dielectrThe effects of dielectric refractive index, prism refractive index and metal film thickness on the surface plasmon resonance (SPR) field enhanced surface-enhanced Raman scattering (SERS) with Kretschmann SPR configuration are studied. Experimental results show that SPR and SERS are essentially correlative. The dielectric refractive index, prism refractive index and metal film thickness have a large effect on SPR field enhanced SERS. Under the same condition, when the dielectric refractive index is small, the SPR field used for SERS signal enhancement and the SERS are great. When the prism refractive index is great, the SPR field enhanced SERS is great. When the silver film thickness increases, the SERS signal intensity increases at first, and then decreases after the SERS signal reaches the largest value. When the silver film thickness is about 47 nm, the SERS signal is the largest..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1207001 (2013)
Measurement and Metrology
Analysis and Metrology of Reproducibility of High-Precision Optic Mount
Wang Hui, Zhou Feng, Wang Liping, Yu Jie, and Jin Chunshui
In order to evaluate the reproducibility of the high-precision optic mount, simulations and tests are undertaken. The model of the optic mount is built in ANSYS, and the residual stress in the mount and the deformation of the mirrors due to disturbance are analyzed, then the reproducibility root mean square (RMS) errorIn order to evaluate the reproducibility of the high-precision optic mount, simulations and tests are undertaken. The model of the optic mount is built in ANSYS, and the residual stress in the mount and the deformation of the mirrors due to disturbance are analyzed, then the reproducibility root mean square (RMS) error of the optic mount is calculated. Calculation results indicate that based on the mount design and assembly accuracy, the reproducibility RMS that the optic mount achieves is better than 0.14 nm. The reproducibility metrology is carried out on the high repeatability interferometer device, and the result indicates that the reproducibility RMS of the optic mount device is better than 0.18 nm, which is in accord with the simulation, and meets the requirement of the reproducibility error budget..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1208001 (2013)
Extraction Algorithm of Circular Targets Used for Mobile Three-Dimensional Measurement
Xie Zexiao, Gao Xiang, and Cui Jian
Circular targets used for mobile three-dimensional (3D) vision measurement system have apparent disadvantages such as low and uneven imaging brightness. An approach based on gray difference weighted centroid algorithm is proposed for the targets′ recognition and extraction. Approximate imaging centers and imaging areasCircular targets used for mobile three-dimensional (3D) vision measurement system have apparent disadvantages such as low and uneven imaging brightness. An approach based on gray difference weighted centroid algorithm is proposed for the targets′ recognition and extraction. Approximate imaging centers and imaging areas of the circular targets are acquired, and then the pixel edge points are detected by scanning the imaging areas in four directions. Sub-pixel edge is located by using gray difference weighted centroid algorithm. And sub-pixel edge points are fitted with ellipse and thus the imaging center positions of the circular targets are acquired. Experimental results indicate that with the proposed algorithm, the elapsed time is about 3 ms, the maximum error of ellipse fitting is less than 0.08 pixel and the average error is less than 0.03 pixel. Compared with other traditional extraction algorithms, it makes great improvement in speed and localization precision, and is more appropriate for the extraction of circular targets used for mobile 3D vision measurement system..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1208002 (2013)
Classification and Comparison of Phase Shift Extraction Algorithms in Generalized Phase-Shifting Interferometry
Li Jie, Wang Yurong, Meng Xiangfeng, Yang Xiulun, Liu Di, Xu Yanghui, and Liu Jingwei
Based on the summarization and classification on different kinds of phase shift extraction algorithms in generalized phase-shifting interferometry (GPSI), an evaluation and comparing method for these GPSI algorithms is proposed according to experimental detectable amount. Based on off-axis digital holography, by using Based on the summarization and classification on different kinds of phase shift extraction algorithms in generalized phase-shifting interferometry (GPSI), an evaluation and comparing method for these GPSI algorithms is proposed according to experimental detectable amount. Based on off-axis digital holography, by using the residual of direct current (DC) term and conjugate image in reconstructed wave field as criterion, GPSI algorithms can then be evaluated and compared by defining the signal-to-noise ratio (SNR) in reconstructed wave field. Theoretical analysis and computer simulation experiment have proven that the bigger the SNR is, the little the residual of DC term and conjuage image is and the more accurate the extracted phase shift is. Six typical algorithms are compared in simulation and optical experiment and the results are consistent, which verify the feasibility and validity of this method..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1208003 (2013)
Accuracy of Photon Pulsed Heterodyne Detection System
Luo Hanjun, and Yuan Xiuhua
Range accuracy is one of the important parameters for evaluating the performance of the pulsed laser ranging system. In this paper, the range accuracy of the photon pulsed heterodyne detection system with Geiger-mode avalanche photodiode (GM-APD) is investigated. Based on the heterodyne principle and statistical detectRange accuracy is one of the important parameters for evaluating the performance of the pulsed laser ranging system. In this paper, the range accuracy of the photon pulsed heterodyne detection system with Geiger-mode avalanche photodiode (GM-APD) is investigated. Based on the heterodyne principle and statistical detection theory of photon counting, the range accuracy model is established. The factors that influence the range accuracy, inculding pulse width, echo intensity, local oscillator (LO) intensity, noise, echo position, and beat frequency, are discussed. The results show that these six factors have significant influence on the range accuracy when the echo intensity is extremely weak. In the case that the primary electrons of the echo signal are beyond 4, the pulse width and echo intensity are the main factors. It is also shown that the stronger echo intensity, the narrower pulse width, the lower noise, the larger echo position, and the less beat frequency, the higher range accuracy in a pulsed photon heterodyne detection system based on GM-APD..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1208004 (2013)
Novel Coaxial Focusing Method Based on Interference
Li Guang, Zhu Jiangping, Chen Mingyong, Zhao Lixin, Hu Song, and Duan Xuanming
A novel coaxial focusing method based on interference is proposed to compensate for the shortage of off-axis focusing methods in immersion lithography. The measurement light is projected on the wafer plane through a lithography objective, and then reflected by the wafer and entries the objective. The resulting image crA novel coaxial focusing method based on interference is proposed to compensate for the shortage of off-axis focusing methods in immersion lithography. The measurement light is projected on the wafer plane through a lithography objective, and then reflected by the wafer and entries the objective. The resulting image created by interference between the reference light and the measurement light is detected by the detection system, so the defocusing amount of the wafer is modulated in the phase of the interference image. The defocusing amount is obtained by demodulating the phase. The simulated experiment shows that the proposed method can achieve a focusing accuracy of λ/25 (λ=632.8 nm), and has good noise immunity, meeting the demand of high-precision, real-time as well as non-contact measurement in immersion lithography..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1208005 (2013)
A Fast Surface Shape Measurement Method for the Parabolic Trough Solar Concentrator Based on Deflectometry
Xiao Jun, Wei Xiudong, Lu Zhenwu, Ren Lanxu, and Shen Zhenfeng
In order to meet the demands of surface shape measurement in trough solar thermal power generation, a fast surface shape measurement technique for trough solar concentrators based on deflectometry principle is proposed after investigating the current research situation in detail. A self-iterative algorithm is used to rIn order to meet the demands of surface shape measurement in trough solar thermal power generation, a fast surface shape measurement technique for trough solar concentrators based on deflectometry principle is proposed after investigating the current research situation in detail. A self-iterative algorithm is used to reconstruct the surface shape and the photogrammetry method is adopted to calibrate the position of the measured concentrators. It makes this measurement system simpler and faster to operate and suitable for online test. The measurement principle of this technique is introduced and the testing platform is built. A piece of parabolic trough solar concentrator is measured. The experimental results indicate that the qualitative surface shape data of the measured mirror can be worked out quickly by using this method. And the feasibility and correctness of this method are verified..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1208006 (2013)
Research on an All-Fiber Structure Velocity Measurement Coherent Lidar
Sui Xiaolin, Zhou Shouhuan, Zhao Hong, Liu Bo, Zhang Ying, and Yan Ziheng
An optical frequency modulated continuous wave coherent lidar technology for velocity measurement based on the Doppler effect is presented. The technology uses all-fiber structure. It has advantages of high efficiency, low power consumption, stable and reliable performance, with good ability to adapt to a mobile platfoAn optical frequency modulated continuous wave coherent lidar technology for velocity measurement based on the Doppler effect is presented. The technology uses all-fiber structure. It has advantages of high efficiency, low power consumption, stable and reliable performance, with good ability to adapt to a mobile platform. Radar principles, structures, data processing algorithms and other related parts are discussed in detail. Flying helicopter hanging results are also given: the maximum measurement velocity is 150 m/s, the measuring range is over 3 km, and the maximum measurement error is 0.08 m/s..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1208007 (2013)
Doppler Frequency Spectral Discrimination of Moving Target Based on Coherent Detection
Peng Shuping, Chen Tao, Yu Hongjun, Zhao Shuai, and Zhang Heyong
Laser coherent detection has applied widely in the area of modern precise detection due to its high sensitivity and anti-disturbance property. The two-dimensional (2D) image information has more ability to reflect the property of the target. Therefore, the PCI8522 data asquisition (DAQ) card and the scanning galvanometLaser coherent detection has applied widely in the area of modern precise detection due to its high sensitivity and anti-disturbance property. The two-dimensional (2D) image information has more ability to reflect the property of the target. Therefore, the PCI8522 data asquisition (DAQ) card and the scanning galvanometer are combined together through analog trigger (ATR) trigger synchronizing for the purpose of receiving the Doppler frequency spectrum. The 2D frequency spectra are obtained for naked and camouflage net covered rotating diffuser, and the imaging size is 31 pixel×31 pixel. The Doppler frequency ranges from 3 MHz to 7MHz, and the target from the noisy background through the 2D frequency spectral image can be distinguished. The noise in the image processing is analyzed and the results are as follows: the area near the center axis of the target has large noise probability and the main reason is the frequency spectral gate with 200 kHz span. The other kind of noise comes form 5 MHz center frequency without Doppler frequency shift restricted by the frequency spectral gate, and there′s no need to wipe off this kind of noises because it is the background of the useful information. This research can be the basis of the application of laser coherent detection in the field of moving target camouflage discrimination..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1208008 (2013)
Optical Communication
Experimental Validation of Effective Nonlinearity Compensation by FIR-BP Algorithm in Polarization Multiplexing System
Li Chunlei, Zhang Xiaoguang, Xi Lixia, Weng Xuan, and Zhao Donghe
Back propagation (BP) algorithm is a common effective method for nonlinear compensation in high-speed fiber optic system. System performance can be improved a lot while the computational complexity can be reduced in the same time if a Gaussian filter is added to BP. However, the Gaussian filter is an ideal filter and iBack propagation (BP) algorithm is a common effective method for nonlinear compensation in high-speed fiber optic system. System performance can be improved a lot while the computational complexity can be reduced in the same time if a Gaussian filter is added to BP. However, the Gaussian filter is an ideal filter and it′s hard to be designed with its complex structure. The scheme that the window finite impulse response (FIR) filter is combined with BP algorithm is proposed. The compensation performance influenced by the filter parameters selection is analyzed in detail, and the performances of different schemes in the 640 km non-dispersion compensation fiber transmission system with 224 Gb/s dual-polarization 16 quadrature amplitude modulation (DP-16QAM) signal are compared. The results prove that the frequency domain characteristics of Hanning FIR filter are similar to the Gaussian function, which can compensate the nonlinear damage and improve the system performance effectively with only 9 taps. Results of the experimental system show that the proposed FIR-BP algorithm can reduce the bit error rate (BER) to 10-3 or less and can increase the optimum fiber input power at least 3 dB compared to the linear compensation algorithms..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1205001 (2013)
Simulation and Experiment on Automatic Polarization Alignment of Fine Polarization Maintaining Fibers
Rong Weibin, Zhang Wei, Wang Lefeng, Cao Yang, Zhao Lei, and Sun Lining
To improve the performance of fine polarization maintaining fiber (PMF) couplers, it is necessary to increase the detection accuracy of polarization axis. The mathematical model of panda PMF index is established, and then the side view method is simulated. From the simulation results, the light is transmitted in the opTo improve the performance of fine polarization maintaining fiber (PMF) couplers, it is necessary to increase the detection accuracy of polarization axis. The mathematical model of panda PMF index is established, and then the side view method is simulated. From the simulation results, the light is transmitted in the optical fiber and is focused on the other side, and the maximum light intensity of the fiber image is related to the rotation angle and the observation distance. When the observation distance is constant, the maximum value of light intensity changes periodically with the PMF rotation angle. When the observation plane is near the focused one of the transmitted light, the highest light intensity of optical image reaches the maximum value, which is the polarization axis detection parameter of PMF. Based on this, detection method which takes the maximum intensity as the feature is proposed. Combining the micro-vision technology, the polarization axis detection system for fine PMF is designed. The image sharpness function which can confirm the position of the detection plane is proposed. The experimental data are processed using the Fourier filtering method. By fitting the experiment data with the cubic spline method, the panda PMF polarization axis is determined. According to the experimental results, the repetitive detection error is 0.61°, which meets the requirements of PMF coupler manufacturing..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1205002 (2013)
Multi-Objective Resources Scheduling Algorithm for Microwave and Laser Hybrid Links Data Relay Satellite Based on Improved NSGA-Ⅱ Algorithm
Zhao Jing, Zhao Weihu, Li Yongjun, Zhao Shanghong, Wang Xiang, Han Lei, and Li Xuan
According to the developed trend for the combination of microwave and laser links in the future data relay satellite system, the resources scheduling problem in data relay satellite system based on microwave and laser links is studied. A multi-objective constrained programming model for microwave and laser links data rAccording to the developed trend for the combination of microwave and laser links in the future data relay satellite system, the resources scheduling problem in data relay satellite system based on microwave and laser links is studied. A multi-objective constrained programming model for microwave and laser links data relay satellites scheduling problem (ML-DRSSP) is presented under the constraint condition of visible time window, mission priority and power consumption of the terminal. By designing the self-adaptive cross, mutation operator and selection operator based on elitism selection, a modified non-domination sorting genetic algorithm Ⅱis improved and the model is solved. A scene simulation is set up on the conditions of a data relay satellite, four user satellites, three resource terminals and scale of different tasks. The simulation results show that the algorithm, by keeping the solution diversity and making non-inferior solution set close as possible to the Pareto optimal solution set, can solve ML-DRSSP with multi-tasking and multi-type antennas, effectively..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1205003 (2013)
Measurement Method and Experimental Research of the Temperature Dependence of the Phase Delay of Quarter-Wave Plates
Wang Xiaxiao, Wang Ye, Li Chuansheng, Qin Yi, Wang Aimin, and Peng Zhiqiang
The fiber quarter-wave plates are an important part of fiber-optic current transformers (FOCT). In order to decrease the error caused by the quarter-wave plates on the ratio under the varying temperature environments, more accurate relationship between the temperature and the phase delay of fiber quarter-wave plates isThe fiber quarter-wave plates are an important part of fiber-optic current transformers (FOCT). In order to decrease the error caused by the quarter-wave plates on the ratio under the varying temperature environments, more accurate relationship between the temperature and the phase delay of fiber quarter-wave plates is required. Based on the intensity method, a measuring way of the temperature dependence of the phase delay of quarter-wave plates is put forward. It is applied to measure fiber quarter-wave plates in real time and continuously. A mathematical model of the test systems is established by using Jones matrix, and the temperature characteristics of the quarter-wave retarder are tested. The experimental results show that: the relationship between the temperature and the phase delay is linear, and the temperature coefficient of inland quarter-wave plates is much larger than that of the abroad ones; in the temperature self compensation technology of ratio error of FOCT, the smaller the temperature coefficient of the phase delay of quarter-wave plates is, the higher the self compensation limit precision is and the wider the original phase retardation is..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1205004 (2013)
Optical Design and Fabrication
Optimization and Figure Analysis of Elastic Thin-Film Liquid Lens
Liu Yongming, Xie Jun, Li Xiangqin, and Liu Zhenyu
In order to meet the requirement of an optical system design on the spherical surface via the thin-film elastic deformation of liquid lens, a numerical optimization method is implemented on the elastomeric supporting region of liquid lens using the solid isotropic material with penalization type topology optimization mIn order to meet the requirement of an optical system design on the spherical surface via the thin-film elastic deformation of liquid lens, a numerical optimization method is implemented on the elastomeric supporting region of liquid lens using the solid isotropic material with penalization type topology optimization model and moving asymptotes constrained optimization algorithm. The topological configuration meeting the convergence conditions is obtained. According to the topology optimization results, the shape optimization is further implemented for key structural dimensions. And a manufactureable elastic thin-film liquid lens is designed according to micromachining technology. Surface error of optical thin-film is analyzed based on the deformation of thin-film. The peak valley (PV) and root mean square (RMS) values about surface error are calculated on the different diameters. The numerical results show that the optical surface error PV values of the optimized structure are 5.7%, 11.9% and 2.5% of the initial structure, respectively, and the RMS values are 11.2%, 21.9% and 45.4% of the initial structure, respectively, at diameters of 100%, 95% and 90% of thin-film and the height of chord of 0.5 mm. The deformation of the optical thin film is fitted with 36 Zernike polynomials. Fitting results show that the 4th, 9th, 16th, 25th Zernike coefficients are also obviously reduced..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1216001 (2013)
Optical System Design of Sensor for Space Rendezvous and Docking
Lü Bo, Liu Weiqi, Zhang Daliang, Kang Yusi, and Feng Rui
An optical system for space rendezvous and docking simulator sensor is designed. The depth of field is increased by using the hyperfocal theory. The problem that the image centroid of signal light in CCD image plane changes with changing object distance is solved by adopting telecentric image space optical design. The An optical system for space rendezvous and docking simulator sensor is designed. The depth of field is increased by using the hyperfocal theory. The problem that the image centroid of signal light in CCD image plane changes with changing object distance is solved by adopting telecentric image space optical design. The lateral aberrations that affect the image centroid seriously is corrected by applying the ameliorative cooke optical configuration. The system has an optical length of 36 mm with 6 pieces of lenses, all of which are spherical surface with no special glass employed. For the 800~880 nm working wavelength and object length of 0.5~130 m, the design quantity of optical absolute distortion is less than ±1 μm with detected precision of field of view approximate to 10″. The designed system meets the requirement of high precision, low cost for manufacture and fine structure. It can be applied in the field of high precision aerocrafts space rendezvous and docking..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1216003 (2013)
Spectroscopy
Fast Lithology Identification by Laser-Induced Breakdown Spectroscopy
Chen Xinglong, Dong Fengzhong, Tao Guoqiang, Li Youjian, She Mingjun, Fu Hongbo, Ni Zhibo, Wang Jingge, He Wengan, Tang Yuquan, and Rao Ruizhong
Laser-induced breakdown spectroscopy (LIBS) has demonstrated its high potential in both qualitative analysis and quantitative analysis. LIBS combined with self-organizing mapping (SOM) neural network is applied in oil prospecting industry. Some rock core samples, including ash rock, mudstone, shale, sandstone and dolosLaser-induced breakdown spectroscopy (LIBS) has demonstrated its high potential in both qualitative analysis and quantitative analysis. LIBS combined with self-organizing mapping (SOM) neural network is applied in oil prospecting industry. Some rock core samples, including ash rock, mudstone, shale, sandstone and dolostone, are automatically classified to lay a foundation for lithology on-line identification. Characteristic variables and principal components, which are obtained by feature extraction from raw spectra, are used as inputs of the SOM neural network, respectively. Classification accuracy is 75% and 86% for the two kinds of inputs, respectively. Particularly, all of ash rocks, sandstone and dolostone are classified correctly when principal components are used as the input. The experimental results indicate that LIBS will be capable of fast identification of lithology after improving the classification accuracy of mudstone and shale..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1215001 (2013)
Spectral Properties of Er3+-Bi3+ Co-Doped Borate Glasses
Gao Yanyang, Jin Lu, Tang Guoyu, Zhao Jian, Xu Xiaofeng, Kang Zhihui, and Wei Jue
The Er3+-Bi3+ co-doped borate glasses are fabricated by the method of oxide high-temperature melting. The absorption and emission spectra are studied. The intensity parameters Ωλ (λ=2,4,6), determined by Judd-Ofelt theory, are calculated to be Ω2=3.8249×10-20 cm2, Ω4=1.6805×10-20 cm2 and Ω6=1.5069×10-20 The Er3+-Bi3+ co-doped borate glasses are fabricated by the method of oxide high-temperature melting. The absorption and emission spectra are studied. The intensity parameters Ωλ (λ=2,4,6), determined by Judd-Ofelt theory, are calculated to be Ω2=3.8249×10-20 cm2, Ω4=1.6805×10-20 cm2 and Ω6=1.5069×10-20 cm2, respectively. The spectral intensity of the electric dipole transitions, the spontaneous radiative transition probabilities and the absorption cross-sections are also calculated. The full width at half maximum (FWHM) and stimulated emission cross-sections of 4I13/2→4I15/2 transition are calculated by McCumber theory. The results show that the FWHM of Er3+-Bi3+ co-doped borate glasses can reach 69.68 nm..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 12, 1215002 (2013)
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