Journals >Chinese Journal of Lasers
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2013
Volume: 40 Issue 2
40 Article(s)
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Polarization Error Analysis of Rotatory Double Reflection Structure
Zhao Guhao, Zhao Shanghong, Yao Zhoushi, Meng Wen, Wang Xiang, Zhu Zhihang, and Liu Feng
By using the polarization characteristics of reflection mirror and cooperating with magneto-optical crystals, the rotatory double reflection structure can automatically compensate the polarization of photons. The polarization independent reflection structure can be used in the movable quantum key distribution system. TBy using the polarization characteristics of reflection mirror and cooperating with magneto-optical crystals, the rotatory double reflection structure can automatically compensate the polarization of photons. The polarization independent reflection structure can be used in the movable quantum key distribution system. The structure requires the polarizations of two mirrors to be absolutely the same and the rotatory angles of magneto-optical crystals to accurately reach 90°. The polarization error caused by mirror mismatch and rotatory angles deviating from 90° is analyzed. The result shows that if the difference between two magneto-optical crystals and two mirrors is kept small enough, good stability of polarization of output pulse can be kept..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 218001 (2013)
Research Article
Analysis of Beam Propagation Through a Relay Mirror System in Turbulent Atmosphere
Wu Huiyun, Chen Jinbao, and Sun Zhenhai
A typical model of the relay mirror system is established, and the appropriate styles of the two adaptive optics installations used in a relay mirror system are analyzed according to the different working conditions and different uses. It is recognized that the adaptive optics installation located at the light source mA typical model of the relay mirror system is established, and the appropriate styles of the two adaptive optics installations used in a relay mirror system are analyzed according to the different working conditions and different uses. It is recognized that the adaptive optics installation located at the light source may use the conjugate adaptive optics, the adaptive optics installation located on the platform may use the optimization algorithm based adaptive optics. Based on a laser relay mirror system under the Hufnagel-Valley 5/7 at atmospheric turbulence model condition and with target height of 25 km, platform height of 30 km, and downlink aiming precision of 1 μrad, necessarity of the second adaptive optics installation its influence on the system performance is analyzed. Performances of beam propagation through the relay mirror system with certain correction precisions of 0, 5th, 10th, 20th and 50th order as well as ideal correction condition are simulated, results show that the two adaptive optics installations have a great impact on the system performance improvement, uplink power efficiency can be improved from 58.82% to 81.27% and power proportion in 0.5 cm bucket at the target can be improved from 1.07% to 15.85% under closed-loop mode with ideal adaptive optics precision..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 213001 (2013)
Beam Transmission and Control
[in Chinese]
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Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 205001 (2013)
Biomedical Photonics and Laser Medicine
Anisotropic Light Diffusion Property of Dentin
Chen Qingguang, Xu Ying, Zhu Haihua, Lin Bin, and Chen Hui
Taking the dentine as the research object, a method to solve the light diffusion properties of anisotropic biological tissue is proposed. The diffusion tensor is introduced into the diffusion equation to describe the light propagation inside the tissue. Through theoretical derivation and considering light diffusion resTaking the dentine as the research object, a method to solve the light diffusion properties of anisotropic biological tissue is proposed. The diffusion tensor is introduced into the diffusion equation to describe the light propagation inside the tissue. Through theoretical derivation and considering light diffusion results of isotropic cubic tissue models, it is proposed that the ratio of diffusion tensor component can be expressed by ratio of long and short axes of forescattering contour ellipse incident by point light source. The experiment is performed to measure the forescattering light intensity distribution of dentine slice from two different directions incident by point light source of 10 μm diameter. The experiment result reveals that the ratio of diffusion tensor component of dentine is DyyDzz:Dxx=7.491.31. The orthogonal anisotropic diffusion equation is solved by finite element analysis method using ANSYS software by setting parameters as the obtained results. The simulated results are compared with the experimental data, and the correctness is confirmed. The study can deepen the understanding of scattering properties of dental dentine and gives the reference for the early detection of dental caries based on scattering effect..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 204001 (2013)
Holography and Information Processing
Phase Aberration Compensation in Pre-Magnification Digital Micro-Holography with Equal-Currature Object Beam and Reference Beam
Wang Huaying, Liu Feifei, Song Xiufa, Liao Wei, Yu Mengjie, and Liu Zuoqiang
In order to fastly and accurately reconstruct the three-dimensional information of the hologram recorded by pre-magnification digital micro-holography, the solution of phase compensation in pre-magnification digital micro-holography with equal-cruvature object beam and reference beam is studied theoretically and experiIn order to fastly and accurately reconstruct the three-dimensional information of the hologram recorded by pre-magnification digital micro-holography, the solution of phase compensation in pre-magnification digital micro-holography with equal-cruvature object beam and reference beam is studied theoretically and experimentally. The point spread function is derived, then the expression of reconstructed light field amplitude and phase aberration are obtained, and by using phase mask to pre-compensate with the phase aberration fastly, the phase for the reconstructed light field is unwrapped. At last, combined with automatic phase compensation, the accurate phase distribution of the sample is obtrained. The red blood cells are researched experimentally. The result shows that phase mask to pre-compensate, not only can avoid the error in phase unwrapped, but also effectively eliminate the secondary phase distortion in the reproduction of light field, which aims to achieve the right phase distribution using single automatic phase compensation method..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 209001 (2013)
Laser Devices and Laser Physics
Femtosecond Laser Drilling of Micro-Holes
Xia Bo, Jiang Lan, Wang Sumei, Yan Xueliang, and Liu Pengjun
With ultrashort pulses and ultra high power densities, femtosecond laser has unique advantages in micro-holes drilling, especially for high-quality and high-aspect-ratio micro-holes. The advantages and study implications of ultrashort pulse laser drilling of micro-holes are introduced. Major progress in femtosecond lasWith ultrashort pulses and ultra high power densities, femtosecond laser has unique advantages in micro-holes drilling, especially for high-quality and high-aspect-ratio micro-holes. The advantages and study implications of ultrashort pulse laser drilling of micro-holes are introduced. Major progress in femtosecond laser drilling of micro-holes is reviewed. The impacts of materials properties, laser parameters, drilling methods and ambient environments are discussed. In addition, potential applications, key challenges and future research trends are presented..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 201001 (2013)
Research Status and Development Trends of Interaction between Laser and Graphene
Jiang Juan, Huang Ting, Zhong Minling, Ye Xiaohui, Lin Zhe, Long Jiangyou, and Li Lin
Recently global researches on graphene materials are exploding due to their outstanding properties. Laser technology is one of the most powerful manufacturing approaches, which makes graphene become a promising candidate for next generation electronic materials. In this work, the reaction mechanism of laser technology Recently global researches on graphene materials are exploding due to their outstanding properties. Laser technology is one of the most powerful manufacturing approaches, which makes graphene become a promising candidate for next generation electronic materials. In this work, the reaction mechanism of laser technology on preparation of graphene is summarized, including pulsed laser deposition (PLD), laser-induced chemical vapor deposition (LCVD), two-beam-laser interference mediated reduction, laser-induced unzipping of carbon nanotubes, and et al.. In addition, to control the quality and photoelectric properties of grapheme, the effect of laser on graphene is discussed, such as thinning, cleaning, cutting, simulated emission, and et al.. Moreover, the applications of micropatterned graphene-based materials on gas sensors, super capacitors are reviewed. At last, the potential use of laser on graphene material in the field of preparation and application is studied..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 201002 (2013)
Laser Manufacturing
Effects of Laser Shock Processing on Cavitation Erosion Resistance of Laser Weldments
Zhang Lei, Luo Kaiyu, Lu Jinzhong, Zhang Yongkang, and Feng Aixin
Effects of laser shock processing (LSP) on cavitation erosion behaviors of ANSI 304 stainless steel thick sheets treated by laser welding are investigated. Mechanical properties and microstructure of laser weldments are measured and observed by X-ray diffraction (XRD), microhardness, electronic balance and scanning eleEffects of laser shock processing (LSP) on cavitation erosion behaviors of ANSI 304 stainless steel thick sheets treated by laser welding are investigated. Mechanical properties and microstructure of laser weldments are measured and observed by X-ray diffraction (XRD), microhardness, electronic balance and scanning electron microscope (SEM) tests in order to investigate cavitation erosion resistance of laser weldments. Results show that with the increment of LSP pulse energies after cavitation erosion, the martensite intensity is improved relatively and the removal of martensite is restrained, the hardness increases, and the cumulative mass loss and damaged surface areas of laser weldments decrease. Meanwhile, the martensite grains are fined, and undulations and upheavals become shallower and sparser, and the growth and propagation of the cracks on the surface are restrained. Thus, cavitation erosion resistance of laser weldments is enhanced. In addition, cavitation erosion resistance of laser welding zone (LWZ) is better than that of heat-affected zone (HAZ)..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 203001 (2013)
Effect of Surface Status on Microstructures and Solidification Cracking Susceptibility in Laser Beam Welding of 2524 Aluminum Alloy
Cai Hua, Kong Xiaofang, and Xiao Rongshi
Aluminum alloy (AA) 2524 is a new aircraft material with high damage tolerance and high strength. Bead-on-plate welding of AA2524 with a thickness of 2 mm using a high power fiber laser is presented. Solidification cracking susceptibility and microstructures of the joints for the original alclad-including surface (OS),Aluminum alloy (AA) 2524 is a new aircraft material with high damage tolerance and high strength. Bead-on-plate welding of AA2524 with a thickness of 2 mm using a high power fiber laser is presented. Solidification cracking susceptibility and microstructures of the joints for the original alclad-including surface (OS), oxide-film removed surface (OR) and alclad removed (AR) surface are investigated by optical microscopy (OM) and electron microscope. The results indicate that the OR and the AR joints have the maximum and minimum solidification cracking susceptibility, respectively. Different surface status joints have different grain sizes, morphologies and quantities of eutectic, leading to the different solidification cracking susceptibilities. The alclad on the surface of AA2524 can dilute the alloying elements in joints, reduce the quantity of eutectic and weaken the healing effect, thus increasing the solidification cracking susceptibility. The oxide-film on the surface of alclad can be involved in welding pool, act as heterogeneous nucleation site playing an important role in refining grain size, promote a discontinuous eutectic distribution and reduce the solidification cracking susceptibility..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 203002 (2013)
A Micro-Damage Model of Laser Cladding Particle Reinforced Composite Coatings
Lü Jun, Chai Guozhong, Gu Shengting, and Bao Yumei
Combining a microscopic damage model based on the Gologanu-Leblond-Devaux constitutive behavior with Mori-Tanaka mean-field homogenization scheme, a ductile fracture model is established, which can describe damage progress of the particle reinforced composites coatings. The numerical simulations of damage model accountCombining a microscopic damage model based on the Gologanu-Leblond-Devaux constitutive behavior with Mori-Tanaka mean-field homogenization scheme, a ductile fracture model is established, which can describe damage progress of the particle reinforced composites coatings. The numerical simulations of damage model accounting for the effects of initial void shape, void size, void volume and particle damage on tensile behavior of laser-processed composite coatings are carried out. In addition, the prediction of the integrated homogenization-damage model is compared with experimental results of laser-cladding H13-TiC composite coatings. The results show that the theoretical prediction and experimental results on uniaxial tension stress-strain curves match well, and the error of maximum fracture strain is in certain range..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 203003 (2013)
Study on Wear-Resistance and Scanning Path of Laser Alloying on End Cap Working Face
Li Shuyu, Tian Xinguo, and Li Chengbiao
The scanning path of laser alloying on the working surface of valve core end caps is programmed based on its shape characteristics and wear conditions. According to the different wear statuses in actual working surface, the working face of valve core end caps is divided into three alloying areas. And a bi-directional sThe scanning path of laser alloying on the working surface of valve core end caps is programmed based on its shape characteristics and wear conditions. According to the different wear statuses in actual working surface, the working face of valve core end caps is divided into three alloying areas. And a bi-directional spiral path is designed in order to achieve those different areas with different alloying area ratios on the working surface. Subsequently, NdYAG laser device is utilized to achieve programming machining, and the fabricated samples are tested in wear test separately with bi-directional spiral scanning path and straight scanning path. It is observed that the wear-resisting property of the working surface of the valve core end caps scanned through bi-directional spiral path is 2.5 times different when scanned by straight scanning path, and its deformation is just about one third of the samples which are scanned by straight scanning path..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 203004 (2013)
Repair Welding Process and Properties of Double-Sided Laser Welding Defects for Aluminum Alloys T-Joints
Yang Zhibin, Tao wang, Li Liqun, Chen Yanbin, Zhang Yunlong, and Liu Shen
Contraposing the welding defects of double-sided laser beam welded 6056/6156 aluminum alloys T-joints for the aircraft panels, systematic research on the repair welding process is carried out from the weld appearance, microstructure, and mechanical properties. The results show that double-sided repair welding with fillContraposing the welding defects of double-sided laser beam welded 6056/6156 aluminum alloys T-joints for the aircraft panels, systematic research on the repair welding process is carried out from the weld appearance, microstructure, and mechanical properties. The results show that double-sided repair welding with filler wire can eliminate the welding defects of the original joints and obtain good weld appearance, and the equiaxial crystal grain refinement is obvious. The dispersively distributed second phase particles in the heat affected zone are reduced, which causes the joints softened more significantly. The transverse tensile strength and axial tensile strength of the double-sided repair joints with filler wire are 323.9 MPa and 183.5 MPa, being 95.8% and 89.8% of the original joints, respectively. Axial tensile fracture surface appears mixed modes of brittle and ductile fracture, and the transverse tensile fracture surface appears brittle fracture characteristics..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 203005 (2013)
Thermo-Induced Regression of Microstructure of Laser-Shocked Surface Modification of 304 Austenitic Stainless Steel
Luo Xinmin, Han Guangtian, Yang Kun, Chen Kangmin, Zhang Yongkang, Ren Xudong, and Luo Kaiyu
Experiments of laser-shocked surface modification of solution-treated 304 austenitic stainless steel specimens are carried out by means of NdYAG laser setup with 1064 nm output wavelength. The phenomenon of the thermo-induced regression and its effect on property of the laser-shocked surface are analyzed via transmissiExperiments of laser-shocked surface modification of solution-treated 304 austenitic stainless steel specimens are carried out by means of NdYAG laser setup with 1064 nm output wavelength. The phenomenon of the thermo-induced regression and its effect on property of the laser-shocked surface are analyzed via transmission electron microscope, scanning electron microscope method and micro-hardness measurement. Experimental results show that deformation microstructure evolution in grains is the basic strengthening mechanism during the surface modification by laser shock processing. The microstructure in the deformed layer of the solution-treated 304 stainless steel consists of stacking faults and partial dislocations, dislocation networks and cells, and deformation twins. These deformation microstructures are liable to regress upon reheating. It is discovered that the regression process includes stacking faults disappearance, dislocation density decreasing and twins decomposition, and surface hardness of the laser-shocked layer returns to the original value of matrix. Meanwhile, micro-damage of deformation twins owing to the internal stress adjustment in the process is observed. Thermo-induced regression coefficient of about 0.35 is obtained for the laser-shocked surface modification of solution-treated 304 austenitic stainless steel..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 203006 (2013)
Effects of Scanning Speed on Microstructures and Properties of Laser Cladding Fe-Based Amorphous Composite Coatings
Lu Qinglong, Wang Yanfang, Li Li, Xiao Lijun, Li Xinmian, Yu Zhiguo, and Shi Zhiqiang
Fe-Cr-Si-P amorphous composite coatings are fabricated on 304L substrates by laser cladding. The effects of laser scanning speed on microstructure and properties of Fe-based amorphous coating are investigated. The results show that the coating mainly consists of amorphous, Fe3P and Fe2Si phases. With the increase of scFe-Cr-Si-P amorphous composite coatings are fabricated on 304L substrates by laser cladding. The effects of laser scanning speed on microstructure and properties of Fe-based amorphous coating are investigated. The results show that the coating mainly consists of amorphous, Fe3P and Fe2Si phases. With the increase of scanning speed, the dendrites gradually refine and the width of epitaxial growth layer decreases. When the laser scanning speed is 400 mm/min, the maximum microhardness of the coating is 821.3 HV0.2, the coefficient of friction under the load of 100 N are 0.076, and the coating shows better properties..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 203007 (2013)
Investigation on Microstructure of Thick Plate Stainless Steel Joint Welded by Multi-Pass Laser Welding with Filler Wire
Wang Baiping, Zhao Yong, and Huang Jian
As a novel way for the joint of thick plate stainless steel, multi-pass laser welding with narrow gap and filler wire can improve the welding efficiency, but seldom research has conducted to the microstructure of this method. In this article, 304 stainless steel plate with 16 mm thickness are welded by CO2 laser weldinAs a novel way for the joint of thick plate stainless steel, multi-pass laser welding with narrow gap and filler wire can improve the welding efficiency, but seldom research has conducted to the microstructure of this method. In this article, 304 stainless steel plate with 16 mm thickness are welded by CO2 laser welding with filler, the microstructure of joint are analyzed by optical microscope, electron backscatter diffraction (EBSD) and energy dispersive spectrometer (EDS). The results show that, fine joint without crack and porosity can be obtained by 8 kW laser power and three pass of welding. The welding seam profile is narrow and high with homogenous width from bottom to top. The heat affected zone (HAZ) is very narrow and no coarse austenitic grains are seen beside fusion line. Two profiles of ferrite such as skeletal and equiaxial exist in welding seam. The characteristic of austenitic is mainly columnar grains and the size is very coarse. There is no obvious change in the area near re-melted region in spite of the re-heating of multi-pass laser welding. The main alloy elements Cr, Ni are distributed evenly in welding seam and no obvious segregation are seen..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 203008 (2013)
Analysis of Radiation Forces Exerted on Defect Particle on the Wafer by a Laser Beam
Gong Lei, Wu Zhensen, Li Zhengjun, Bai Lu, and Gao Ming
Based on generalized Lorenz-Mie theory, the radiation forces exerted on defect particle on the wafer by a laser beam are derived combing the scattering theory about sphere particle to clean the defect particle in the optical nondestructive examination. According to relationship between spherical vector wave functions aBased on generalized Lorenz-Mie theory, the radiation forces exerted on defect particle on the wafer by a laser beam are derived combing the scattering theory about sphere particle to clean the defect particle in the optical nondestructive examination. According to relationship between spherical vector wave functions and triangle functions, the analytical expressions of the axial radiation force and the transverse radiation force exerted on defect particle by an Gaussian beam are given and the influences of many factors on the radiation forces are analyzed numerically in details. The results show that the maximum radiation forces become larger with the particle radius becoming less. The energy of optical axis and scattering forces become less with the particle radius becoming larger. The smaller the dielectric constant, the smaller the radiation force. In the project, the smaller beam waist widths is used with much more energy to clear the defect particle more efficiently. In addition, the defect particle material is detected by quantitative analysis to radiation forces..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 203009 (2013)
Laser Physics
Erbium-Doped Fiber Laser Based on Single-Layer Graphene Saturable Absorber
Huang Wenyu, Feng Dejun, Jiang Shouzhen, Ji Wei, Jiang Mingshun, and Sui Qingmei
As an ideal saturable absorber material, graphene has attracted widespread attentions, which can be used as saturable absorber in passive mode-locking lasers because of its perfect electronic and optical characteristics. Single-layer graphene film fabricated on the copper foil by using chemical vapor deposition method.As an ideal saturable absorber material, graphene has attracted widespread attentions, which can be used as saturable absorber in passive mode-locking lasers because of its perfect electronic and optical characteristics. Single-layer graphene film fabricated on the copper foil by using chemical vapor deposition method. The corresponding Raman spectroscopy is measured. The graphene film is transferred to the facet of zirconium oxide of a fiber jumper. The mode-lock Er3+-doped fiber laser with graphene film as saturable absorber is experimentally studied, which has a ring structure and use a fiber Bragg grating with transmissivity of 92% to select output frequency. The laser has a peak wavelength of 1556.7 nm, 3 dB bandwidth of 0.068 nm, pulse repetition rate of 6.042 MHz and threshold of 65 mW..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 202001 (2013)
Polarization Properties of the Eigenmodes in the Four-Mode Differential Laser Gyro with Perturbation Method
Zhao Hongchang, and Wang Zhiguo
In order to obtain ideal circularly polarized laser in the four-mode differential laser gyro, the influence of cavity parameters on polarization degree is analyzed with perturbation method. The perturbation matrix to the first order approximation is derived. Not only anisotropies of cavity mirrors but also optical actiIn order to obtain ideal circularly polarized laser in the four-mode differential laser gyro, the influence of cavity parameters on polarization degree is analyzed with perturbation method. The perturbation matrix to the first order approximation is derived. Not only anisotropies of cavity mirrors but also optical activity and linear birefringence of quartz crystal are considered for planar four-mode differential laser gyro, while anisotropies and nonplanar rotation angle of carity mirrors are considered for nonplanar four-mode differential laser gyro. The first order perturbation solution of eigen-vector is obtained with perturbation method for eigen problem of matrix. The variation of polarization degree as a function of anisotropies of cavity mirrors is discussed when the rotation angle of the cavity is 90°. Expressions derived from perturbation method agree well with strict numerical solutions when polarization degree is less than 0.05. Polarization degrees of four-mode differential laser gyros as a function of anisotropies of mirrors are different between palanar and nonplanar cavity. The results have certain instructive effect for optimizing the cavity design of four-mode differential laser gyro..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 202002 (2013)
Research on LD-End-Pumped 457 nm Laser with Straight Type Cavity
Yin Hao, Zhu Siqi, Yang Qiguo, Chen Zhenqiang, He Qing, Li Anming, and Li Zhen
In order to give full play to the advantages of compact all-solid-state lasers, a compact straight cavity 457 nm blue laser system is designed. Based on the nature of the Nd:YVO4, the analysis of laser threshold of quasi-three-level laser system and the parameters optimization of resonator cavity are obtained. The laseIn order to give full play to the advantages of compact all-solid-state lasers, a compact straight cavity 457 nm blue laser system is designed. Based on the nature of the Nd:YVO4, the analysis of laser threshold of quasi-three-level laser system and the parameters optimization of resonator cavity are obtained. The laser of Nd:YVO4 operation at 914 nm and its 457 nm second harmonic is realized by intracavity frequency doubling with BIBO nonlinear crystal. The highest output power at 457 nm reaches 1.56 W with an incident pump power of 24.2 W, and the optical-to-optical conversion efficiency is higher than 6.45%, also the fluctuation of the blue output power is less than 2.98% and M2 factor is 1.3..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 202003 (2013)
Ring Semiconductor Laser with Multi-Ring Coupling Structure
Zhang Siyu, Qiao Zhongliang, Zhou Lu, Wang Yunhua, Jia Baoshan, Liu Chunling, Bo Baoxue, Gao Xin, and Qu Yi
To improve the spectral purity, brightness and stability of semiconductor lasers, multi-ring coupling structure of the semiconductor laser is investigated. Based on the structure of multi-ring coupling and output of the curved active waveguide, spectral purity brightness, and output stability of ring laser structure arTo improve the spectral purity, brightness and stability of semiconductor lasers, multi-ring coupling structure of the semiconductor laser is investigated. Based on the structure of multi-ring coupling and output of the curved active waveguide, spectral purity brightness, and output stability of ring laser structure are greatly improved. The parallel far-field divergence angle of slow axis is up to 2.7° and output power of 10 mW is obtained. Spectral width reaches 0.26 nm at 821 nm, the Q factor is up to 2737. It is found that the multi-ring coupling structure laser device owns current modulation characteristics with its spectrum, whose modulation range is closed to 15 nm. Meanwhile, the operation current owns a certain modulation to spectral width, whose modulation capability is about 0.2 nm. The optimized multi-ring coupling structure laser output spectral width narrowed to 0.2 nm and a Q factor of 4040 is obtained..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 202004 (2013)
Wavelength Switchable Passive Mode-Locking Fiber Laser Based on Single-Wall Carbon Nanotube
Zhu Pan, Sang Mei, Gao Yang, Wang Xiaolong, Liu Ke, Wang Junlong, and Yang Tianxin
A passively mode-locked fiber laser, whose operating wavelength can be switched based on the single-wall carbon nanotube saturable absorber (SWCNT-SA), is demonstrated. By adjusting the thickness of saturable absorber film to change the intracavity loss, not only stable mode-locked output is obtained, but also the gainA passively mode-locked fiber laser, whose operating wavelength can be switched based on the single-wall carbon nanotube saturable absorber (SWCNT-SA), is demonstrated. By adjusting the thickness of saturable absorber film to change the intracavity loss, not only stable mode-locked output is obtained, but also the gain profile of the erbium-doped fiber laser is effectively controlled. The experimental results show that the lasers can generate mode-locked pulses with the central wavelength of 1545 nm and 1562 nm, in the thinner and thicker SWCNT-SA, respectively. Additionally if the thickness of SWCNT-SA is appropriately controlled between the thinner and thicker ones, the laser can generate pulses both with central wavelength of 1545 nm and 1562 nm, and the operating wavelength can be switched from one to the other by carefully adjusting the polarization controller. In the process of wavelength switching, the phenomenon of mode-locking is also observed when the two central operating wavelengths simultaneously appear..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 202005 (2013)
Thulium-Doped All-Fiber Broadband Superfluorescent Source at 2 μm Wavelength
Liu Jiang, and Wang Pu
A high power 2.0 μm thulium-doped broadband amplified spontaneous emission (ASE) source is reported by using an all-fiber master oscillator power-amplifer (MOPA) configuration. The ASE seed source produces average output power of about 220 mW by using a segment of thulium-doped double-clad fiber pumped by fiber-pigtailA high power 2.0 μm thulium-doped broadband amplified spontaneous emission (ASE) source is reported by using an all-fiber master oscillator power-amplifer (MOPA) configuration. The ASE seed source produces average output power of about 220 mW by using a segment of thulium-doped double-clad fiber pumped by fiber-pigtailed multimode diodes at 790 nm. The center wavelength and the 3 dB bandwidth are 1952 nm and 40 nm, respectively. A thulium-doped all-fiber amplifier is used to boost average output power to 2.6 W with a slope efficiency of 46% with respect to the launched pump power. The emission spans the wavelength range from 1900 nm to 2100 nm with a 3 dB bandwidth of 33 nm, and the maximum output power of the ASE fiber amplifier is currently limited by available pump power..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 202006 (2013)
Simulation Study on Amplitude Stability in Nonlinear Polarization Rotation Mode-Locked Fiber Laser
Li Chao, Zhao Lei, Huang Zhihua, Lin Honghuan, Deng Ying, Huang Xiaojun, and Zhu Qihua
A numerical model for nonlinear polarization rotation mode-locked fiber laser is established based on coupled wave equations and Jones matrix. The numerical results show that the power jitter of pump laser seriously affects amplitude jitter of mode-locked fiber laser. The root mean square (RMS) value of mode-locked pulA numerical model for nonlinear polarization rotation mode-locked fiber laser is established based on coupled wave equations and Jones matrix. The numerical results show that the power jitter of pump laser seriously affects amplitude jitter of mode-locked fiber laser. The root mean square (RMS) value of mode-locked pulse is 0.82%, and peak-to-valley value is 2.84% when random jitter of pump power is ±3%. Cavity length jitter has less effect on amplitude jitter. However, cavity length jitter leads to large timing jitter. So in order to get mode-locked pulses with very low timing jitter and amplitude jitter, pump laser power jitter and cavity length jitter must be controlled..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 202007 (2013)
Properties of Vortex Beams with Plane Beam Oblique Incidence of Fork-Shaped Grating
Meng Xiangjun, Zhu Yanying, Chen Zhiting, Wei Yong, Zhang Lei, Zhao Baolin, and Guo Xihua
Based on the fork-shaped grating produced by the computer-generated hologram (CGH), the effect of the plane beam oblique incidence of fork-shaped grating on the vortex beams property is discussed. The theoretical study shows that when the plane beam tilts into the fork-shaped grating, the distance of each both symmetriBased on the fork-shaped grating produced by the computer-generated hologram (CGH), the effect of the plane beam oblique incidence of fork-shaped grating on the vortex beams property is discussed. The theoretical study shows that when the plane beam tilts into the fork-shaped grating, the distance of each both symmetric distributed vortex beams is changed with the angle α between the planar optical and the grating. The experiments show that the distance of the symmetric distributed diffractive vortex beams spots increases with α. The research results show that the generation of high quality vortex beams is feasible with CGH in experiments..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 202008 (2013)
Materials and Thin Films
Properties of TiO2 Films Deposited by Pulsed Laser Deposition
Xing Xiao, Wang Wenjun, Li Shuhong, Liu Yunlong, Zhang Dong, Shi Qiang, Gao Xuexi, and Zhang Bingyuan
The TiO2 films are deposited on glasses by pulsed laser deposition (PLD), and the effects of substrate temperature and oxygen pressure on the surface morphology, structure and optical properties of TiO2 films are studied. The results show that the refractive index of TiO2 films increases until the substrate temperatureThe TiO2 films are deposited on glasses by pulsed laser deposition (PLD), and the effects of substrate temperature and oxygen pressure on the surface morphology, structure and optical properties of TiO2 films are studied. The results show that the refractive index of TiO2 films increases until the substrate temperature reaches 300 ℃, decreases from 300 ℃ to 400 ℃, increases from 400 ℃ to 500 ℃, and gets the maximum at 300 ℃. The refractive index decreases when the oxygen pressure getting higher. The X-ray diffraction (XRD) diagrams demonstrate that the structure of TiO2 films are all amorphous when the growth temperature is under 300 ℃，transforms into anatase structure at 300 ℃, and keeps anatase from 300 ℃ to 500 ℃. The crystallization degree is the best at 300 ℃. The atomic force micrographs (AFM) of the TiO2 films manifest that the particle size increases with the substrate temperature increasing till 300 ℃. When the substrate temperature exceeds 300 ℃, the average particle size remain unchanged almost, and the grain arrangement is best-orderly when the substrate temperature is 300 ℃. According to the transmission spectra, the band gap width of TiO2 thin films is calculated. It is recorgnized that the width of the band gap gets wider while the substrate temperature goes up, but narrower while the oxygen pressure increases..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 207001 (2013)
Measurement and Metrology
Laser Ranging System Based on High Speed Pseudorandom Modulation and Photon Counting Techniques
Yang Fang, Zhang Xin, He Yan, and Chen Weibiao
A laser ranging system based on high speed pseudorandom modulation and photon counting technology is developed. 1550 nm fiber laser modulated by 10 order M sequence pseudorandom code and InGaAs/InP single photon detector with three-stage thermo-electric cooler are implemented in the system. The ranging performance is dA laser ranging system based on high speed pseudorandom modulation and photon counting technology is developed. 1550 nm fiber laser modulated by 10 order M sequence pseudorandom code and InGaAs/InP single photon detector with three-stage thermo-electric cooler are implemented in the system. The ranging performance is demonstrated using the optical fiber delay method indoor. Under condition of the laser modulation frequency of 622 MHz, the pseudorandom sequence length of 1.64 μs and the detection efficiency of 10%, the signal-to-noise ratio of 22.6 dB and ranging accuracy of 0.95 cm are obtained with -76.1 dBm input signal average power. This demonstration is useful for developing practiced system..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 208001 (2013)
Measurement System for Dynamic Envelope Curve of High-Speed Train
Guo Yin, Liu Changjie, Zhu Jigui, Liu Gang, Gao Fulai, and Ye Shenghua
Dynamic envelope curve is one of the key factors to be considered when defining the dynamic gauge. To accurately obtain the dynamic envelope curve is one big step in design vehicle and also an insurance against dangers in driving. Since the major way to obtain dynamic envelope curve now is by enormous calculation, a meDynamic envelope curve is one of the key factors to be considered when defining the dynamic gauge. To accurately obtain the dynamic envelope curve is one big step in design vehicle and also an insurance against dangers in driving. Since the major way to obtain dynamic envelope curve now is by enormous calculation, a measurement system is designed for measuring dynamic envelope curve of high-speed train. Based on binocular vision, the system produces the feature using high power pulse laser, and obtains the dynamic envelope curve of the high-speed train by high-speed acquisition, process and calculation of information that reflects the excursion of train. One field calibration method is proposed to build quickly and efficiently both the position relationship between the two cameras and the transformation between center coordinate system of railway and coordinate system of measurement system. It is proved by experimental results that the measurement precision of the system can reach up to ±0.5 mm, and that the measurement of the dynamic envelope curve of high-speed train is accomplished with high reliability, which can provide useful statistics for the definition of dynamic gauge of high-speed train..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 208002 (2013)
Optical Communication
Performance Research on the Non-Clipped QPSK Sine-Like Modulation of Atmospheric Laser Communication System
Deng Lijun, Ke Xizheng, and Shi Weijian
A non-clipped quadrature phase shift keying (QPSK) sine-like modulation technology is proposed in this paper and applied to the atmospheric laser communication system. The atmospheric laser communication channel model is introduced and the atmospheric laser communication system model of non-clipped QPSK sine-like modulA non-clipped quadrature phase shift keying (QPSK) sine-like modulation technology is proposed in this paper and applied to the atmospheric laser communication system. The atmospheric laser communication channel model is introduced and the atmospheric laser communication system model of non-clipped QPSK sine-like modulation is given. Based on there, the power efficiency, bit error rate (BER), outage probability and channel capacity of atmospheric laser communication systems which adopt non-clipped QPSK sine-like modulation and direct current bias sub-carrier intensity modulation are compared and analyzed. The results demonstrate that the proposed scheme has better anti-noise performance, higher power utilization, lower outage probability and higher channel capacity, and improves the performance of atmospheric laser communication system. The scheme can satisfy the requirements of atmospheric laser communication system..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 205001 (2013)
Research on Dynamic Model of Digital Closed-Loop Fiber Optic Gyroscope
Wang Xiaxiao, Zhang Meng, Li Chuansheng, Wang Aimin, and Peng Zhiqiang
It is difficult to verify the dynamic model of the digital closed-loop fiber optic gyroscope (FOG) due to the limitation of the turntable′s output frequency. To solve this problem, a novel evaluation method based on the magneto-optic Faraday effect is developed. The Sagnac phase difference is substituted by the FaradayIt is difficult to verify the dynamic model of the digital closed-loop fiber optic gyroscope (FOG) due to the limitation of the turntable′s output frequency. To solve this problem, a novel evaluation method based on the magneto-optic Faraday effect is developed. The Sagnac phase difference is substituted by the Faraday phase difference induced by alternating current (AC) to eliminate the limitation of stimuli. Based on the dynamic system model of the FOG, the relationship between bandwidth and the parameters is analyzed and the system transfer function is obtained. The frequency response characteristic of the gyro is simulated via the obtained transfer function. Finally, some experiments are conducted to investigate the dynamic performance of the gyro. The experimental data are in agreement with the theoretical findings, which demonstrates the correctness of the dynamic model and provides the groundwork for optimizing dynamic characteristics..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 205002 (2013)
Interrogation Technology for High-Speed and High-Resolution Fiber Bragg Grating Sensing System
Wang Yongjun, Liu Yongchao, Zhang Jingtao, Yang Zhaoyi, and Wang Zhi
A new interrogation scheme based on semiconductor optical amplifier (SOA) ring laser and tunable Fabry-Perot (F-P) interferometer for fiber Bragg grating (FBG) sensing system is proposed. In the interrogation scheme, a gas absorption spectral line is used as a wavelength reference, and a comb filter is designed as a stA new interrogation scheme based on semiconductor optical amplifier (SOA) ring laser and tunable Fabry-Perot (F-P) interferometer for fiber Bragg grating (FBG) sensing system is proposed. In the interrogation scheme, a gas absorption spectral line is used as a wavelength reference, and a comb filter is designed as a standard device that can dynamically calibrate the wavelength of FBG sensors. With digital signal processing technology and wavelength detection algorithm based on the 3 dB-power point, more than 1000 temperature sensors or 240 strain sensors can be interrogated with frequency of 1000 Hz. Experiment demonstrates that the strain measuring accuracy and wavelength resolution can reach to 0.6 με and 0.5 pm, respectively, and the temperature measuring precision can reach to 0.05 ℃..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 205003 (2013)
Design of Hollow-Core Bragg Fiber with Broadband Transmission for Trace-Gas Detection
Shang Liang, Zhang Lichun, and Qi Limei
A novel design of hollow-core Bragg fibers (HC-BFs) with linearly-chirping distributed dielectric cladding is proposed, for demand of the multi-component trace-gas detection based on the mid-infrared (mid-IR) absorption spectrum. The photonic band-gap (PBG) structures and transmission-loss characteristics for the TE anA novel design of hollow-core Bragg fibers (HC-BFs) with linearly-chirping distributed dielectric cladding is proposed, for demand of the multi-component trace-gas detection based on the mid-infrared (mid-IR) absorption spectrum. The photonic band-gap (PBG) structures and transmission-loss characteristics for the TE and TM modes under nearly glancing incidence condition in such a quasi-periodic HC-BF are numerically investigated and compared with a conventional one with periodic cladding. The results show that the quasi-periodic cladding can effectively enlarge the PBG width by increasing the linear increment of cladding period and dielectric-layer number. The enlargement effect enhances with the increment of both structure parameters. Meanwhile, the central wavelength of the PBG shifts to the longer wavelength. In the enlarged wavelength range of PBG, the HC-BF with linearly-chirping distributed dielectric cladding still has the low loss, in the order of 0.01 dB/m, showing the excellent performance of mid-IR low-loss broadband transmission..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 205004 (2013)
Research on Fiber Grating Pressure/Temperature Monitoring Device of Distinguish Range and Double Sensitivity
Pan Hongliang, Dong Huijuan, Zhang Guangyu, and He Jun
A fiber grating pressure/temperature monitoring device of distinguish range and double sensitivity is developed. Using the Package structure of distinguish range, the pressure measuring range of sensor under the premise of no changing monitoring index of fiber grating is expanded. The size and material of package strucA fiber grating pressure/temperature monitoring device of distinguish range and double sensitivity is developed. Using the Package structure of distinguish range, the pressure measuring range of sensor under the premise of no changing monitoring index of fiber grating is expanded. The size and material of package structure are set to realize the double sensitivity and integration monitoring of pressure and temperature. The monitoring performance of pressure and temperature is tested in experiment, and the results show that the range of pressure measuring is from 0 to 30 MPa, the range of temperature measuring is from 0 ℃ to 150 ℃. Pressure measuring sensitivity are 352.5 pm/MPa and 223.3 pm/MPa respectively under the monitoring range of 0~15 MPa and 15~30 MPa, and linear degrees are 99.42% and 99.33% respectively. Temperature measuring sensitivity are 33.5 pm/℃ and 22.5 pm/℃ respectively, and linear degrees are 99.69% and 99.61% respectively. The proposed monitoring device is simple in structure, which has superior performance and high application value..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 205005 (2013)
All-Optical Switching in Silicon-on-Insulator Serially Coupled Double-Ring Resonator Based on Thermal Nonlinear Effect
Liu Yi, Tong Xiaogang, Yu Jinlong, Xue Chenyang, Wang Wenrui, Guo Jingzhong, Wang Ju, Han Bingchen, and Yang Enze
One of the major challenges in realizing all-optical switching is urgent demand for dense integration and high extinction ratio (ER). In this paper, all-optical switching in silicon-on-insulator (SOI) serially coupled double-ring resonator based on thermal nonlinear effect is proposed. The radii of double ring resonatoOne of the major challenges in realizing all-optical switching is urgent demand for dense integration and high extinction ratio (ER). In this paper, all-optical switching in silicon-on-insulator (SOI) serially coupled double-ring resonator based on thermal nonlinear effect is proposed. The radii of double ring resonator are both 10 μm. Theoretically, switching ER is improved at the same resonance wavelength of serially coupled double-ring resonator. Then, basic characteristics of all-optical switching in serially coupled double-ring resonator based on thermal nonlinear effect are researched. In experiments, firstly measured by single pump injection technology with easily coupling surface grating coupler method, the highest notch of serially coupled double-ring resonator is 27 dB. And the highest ER is 20.2 dB based on thermal nonlinear effect by adjusting the power of injected light. The slope of resonant wavelength as a function of injected pump is 136.4 pm/mW. Secondly, switching time measured by two pump injection technology is 2.84 μs and 3.04 μs, respectively. The results which are in agreement with theory between single and two-pump-injection technology are compared and analyzed. Those provide efficient method for optical router and modulation with dense integration and high performance..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 205006 (2013)
Positioning Accuracy of Spot-Detecting Camera in Acquisition, Tracking, Pointing System
Qian Feng, Jia Jianjun, Zhang Liang, and Wang Jianyu
Requirements of high-precision spot detection in laser communication acquisition, tracking, pointing (ATP) systems are analyzed, and the advantages of selecting complementary metal-oxide-semiconductor (CMOS) sensor are explained. According to the needs, design principles of a spot-detecting camera based on STAR-1000 seRequirements of high-precision spot detection in laser communication acquisition, tracking, pointing (ATP) systems are analyzed, and the advantages of selecting complementary metal-oxide-semiconductor (CMOS) sensor are explained. According to the needs, design principles of a spot-detecting camera based on STAR-1000 sensor as well as hardware implementation methods of centroid algorithm are expounded. The positioning accuracy of the camera is affected by some defects, for example noise and limited duty cycle in the CMOS sensor. Several factors in positioning accuracy are analyzed and the effect is simulated. Test results from imaging experiment system formed verify these analyses. According to the experiment designer can improve positioning accuracy by reducing noise, improving duty cycle, and expanding the effective spot diameter. And then, suggestions for improving positioning accuracy are put forward which contrapose laser communication ATP system..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 205007 (2013)
Optical Design and Fabrication
Design of Micro-Cylindrical-Lens Array Used for Illumination Uniformization in Lithography Systems
Xiao Yanfen, Zhu Jing, Yang Baoxi, Hu Zhonghua, Zeng Aijun, and Huang Huijie
Uniform illumination is an important condition for maintaining high uniformization consistence of lithography lines in projection lithography. Micro-lens array used as the illumination uniformization component can make the rectangular illumination spot as well as acquire high far field uniformization. Based on modern pUniform illumination is an important condition for maintaining high uniformization consistence of lithography lines in projection lithography. Micro-lens array used as the illumination uniformization component can make the rectangular illumination spot as well as acquire high far field uniformization. Based on modern processing technology, the cylindrical micro-lens array divided in two-dimension is designed, and the central bright line in the far field created by the transition area between the micro-lens array is eliminated. Simulation results show that the far field non-uniformi of the designed micro-lens array reaches 0.85%..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 216001 (2013)
Remote Sensing and Sensors
Realization of Measuring Micro-Vibration Based on Phase Generated Carrier Modulation-Demodulation Method and Interference Analysis
Tang Weijie, Fu Lei, Chen Shufen, Zou Zhengfeng, and Meng Yanbin
The basic principle of measuring micro-vibration based on phase generated carrier (PGC) modulation-demodulation method is analyzed. A Michelson interferometer measurement system is set up and the micro-vibration measurement of acoustic frequency band signal is studied. Based on this, influences of random fluctuations oThe basic principle of measuring micro-vibration based on phase generated carrier (PGC) modulation-demodulation method is analyzed. A Michelson interferometer measurement system is set up and the micro-vibration measurement of acoustic frequency band signal is studied. Based on this, influences of random fluctuations of the vibration frequency and the phase mismatch in the modulation of the piezoelectric ceramic (PZT) on the demodulator are analyzed. Theoretical and experimental results show that the stability of the PZT modulation has a great impact on the final demodulated waveform. The stability of the modulation frequency can eliminate the signal distortion caused by demodulation, and phase matching makes the demodulated signal to noise ratio (SNR) maximum. In order to reduce the influence of PZT, the experimental system is improved..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 214001 (2013)
Effects of Coating on Sensitivity of Photonic Crystal Biosensor
Tong Kai, Zeng Wenzhi, Gu Chaocong, Wang Huibo, and Lu Jianru
A polymer photonic crystal biosensor with a period of 1000 nm is proposed on a SiO2 substrate. Then a high refractive index material is deposited on the surface of the photonic crystal. The rigorous coupled-wave theory is employed to analyze the characteristics of the narrow-band infrared reflection spectrum of the phoA polymer photonic crystal biosensor with a period of 1000 nm is proposed on a SiO2 substrate. Then a high refractive index material is deposited on the surface of the photonic crystal. The rigorous coupled-wave theory is employed to analyze the characteristics of the narrow-band infrared reflection spectrum of the photonic crystal biosensor, and the relation between the peak reflection wavelength and the effective refractive index is established. With concentration of the analyte adsorbed on the surface of the photonic crystal varying, the effective refractive index changes simultaneously, which leads to a shift of the peak reflection wavelength. Therefore, the distribution of the analyte according to the amount of shift of the peak reflection wavelength is obtained. The influence of the coating with different refractive indices, thicknesses and filling ratios on the reflection spectrum and sensitivity of the shift of the peak reflection wavelength is also studied. The results indicate that the sensitivity of the biosensor can be improved by selecting appropriate parameters of the coating..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 214002 (2013)
Optimized Design of Parameters Affecting the Accuracy of Airborne LIDAR by Using Orthogonalization-Based Experiments
Wang Jianjun
It is very important to select reasonable values of various operating parameters of airborne laser imaging radar (LIDAR), which are closely related to the measurement accuracy of airborne LIDAR. In order to obtain reasonable configuration values of various operating parameters, the three-dimensional (3D) coordinate errIt is very important to select reasonable values of various operating parameters of airborne laser imaging radar (LIDAR), which are closely related to the measurement accuracy of airborne LIDAR. In order to obtain reasonable configuration values of various operating parameters, the three-dimensional (3D) coordinate errors of laser footprints from airborne LIDAR are deduced, and error factors and operating parameters affecting the positioning accuracy of the laser footprints are determined. Then, based on orthogonal experimental design, three levels of configuration values of various operating parameters are selected, respectively, and by cross combination, eighteen orthogonal experiments are designed. For each of the eighteen orthogonal experiments with different levels of configuration values of the operating parameters, the airborne laser scanning procedure are simulated, respectively, and the corresponding 3D coordinate errors of the laser footprints are calculated. By orthogonal experimental error analysis, the optimal configuration values of the operating parameters are obtained. Furthermore, the configuration characteristics and laws of various operating parameters are analyzed, which provide a theoretical guidance for improving the measurement accuracy of airborne LIDAR..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 214003 (2013)
Spectroscopy
Raman Spectroscopic Analysis of Ethanol Fermentation at Various Initial pH Levels
Qin Zhaojun, Lai Junzhuo, Liu Bin, Liu Junxian, and Wang Guiwen
The pH level is a prominent factor affects the ethanol fermentation. Optical tweezers Raman spectroscopy is used to analyze the process of ethanol fermentation at the initial pH levels of 3.0, 4.5, 6.5. Major results from this work are as follows: 1) The pH 4.5 level get the highest ethanol production and the pH 3.0 geThe pH level is a prominent factor affects the ethanol fermentation. Optical tweezers Raman spectroscopy is used to analyze the process of ethanol fermentation at the initial pH levels of 3.0, 4.5, 6.5. Major results from this work are as follows: 1) The pH 4.5 level get the highest ethanol production and the pH 3.0 get the lowest one. 2) Raman intensities of bio-macromolecules of yeast cells at all pH levels exhibite dramatic changes in the first 15 hours. However, at the later stage of the fermentation, the pH 3.0 level displayes strong Raman intensities of intracellular lipids and proteins while pH 6.5 level shows weak. This indicates that a portion of substrate may be transformed into intracellular storage material by yeast cells at lower pH level. 3) Principal component analysis reveals that fermentation pH influences the physiological status of yeast cells from the beginning of fermentation, and bands 1440 cm-1 and 1600 cm-1 are the prominent contributors to the component loadings in different fermentation stages. This suggests the pH level of medium may affect the synthesis of lipid and the respiratory metabolism of yeast cells, influence the metabolism consequently. The results indicate Raman spectroscopy and single-cell analysis can uncover the physiological mechanism of the microbial cell during the fermentation process and provide new and reference information for the ethanol fermentation..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 215001 (2013)
Study on the Liquid Jet Dual Pulse Laser-Induced Ca Plasma Emission Spectroscopy
Zhang Qiao, Hu Zhenhua, Ding Lei, Wang Yingping, Zheng Haiyang, and Fang Li
Dual pulse laser-induced breakdown spectroscopy (LIBS) of Ca is studied in liquid jet. The influence of the experimental conditions, including delay of integration, inter pulse delay, on the emission intensity is investigated. It is found that Ca plasma emission intensity is greatly enhanced and the inter pulsed delay Dual pulse laser-induced breakdown spectroscopy (LIBS) of Ca is studied in liquid jet. The influence of the experimental conditions, including delay of integration, inter pulse delay, on the emission intensity is investigated. It is found that Ca plasma emission intensity is greatly enhanced and the inter pulsed delay time has a great impaction of emission intensity, and there is a maximum around 0.4 μs. And at this time, plasma emission time is apparently longer in dual pulse excitation than that in single pulse excitation mode. Then the calibration curves of Ca elements with different concentrations in the liquid are acquired. The limit of detection in dual pulse laser with 0.4 μs interval excitation mode is about 5 times lower than that in single pulse. The results offer feasibility and basis for the detection of metallic elements in liquid by dual pulse-LIBS..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 2, 215002 (2013)
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