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Contents
2014
Volume: 41 Issue 7
46 Article(s)
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[in Chinese]
Correlation Analysis and Calibration of Noninvasive Blood Glucose Monitoring in vivo with Optical Coherence Tomography
Su Ya, Meng Zhuo, Wang Longzhi, Yu Haimin, Liu Tiegen, and Yao Xiaotian
The living human skin has complex composition of tissue in several distinctive layers with various thicknesses, and different tissues have different glucose dependence of optical properties. Therefore, the calculation analysis method to find the maximum correlation region containing minimum noise to be used for calibraThe living human skin has complex composition of tissue in several distinctive layers with various thicknesses, and different tissues have different glucose dependence of optical properties. Therefore, the calculation analysis method to find the maximum correlation region containing minimum noise to be used for calibration is worth being concerned in noninvasive blood glucose monitoring. We report an algorithm using correlation analysis to calculate the depth of region, which has the maximum correlation between blood glucose concentration and tissue optical properties. The selected correlation region also has the least noise interference from other skin layers. This method can improve the prediction precision of the noninvasive blood glucose concentration measuring and has a value for application..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 704002 (2014)
[in Chinese]
Investigation of Characteristics of Single mode-Multimode-Single mode All-Fiber Optic Current Sensor with Broadband Light Source Inputting
Zhang Rongxiang, Han Qun, Liu Tiegen, Chen Yaofei, and Li Lin
A single mode-multimode-single mode fiber optic structure and magnetic fluid based all-fiber optic current sensor, which can be interrogated by monitoring the dip wavelength shift or transmission loss of the transmission spectrum, is designed. For the first interrogation method, the current sensitivity of 1243.7 pm/A [A single mode-multimode-single mode fiber optic structure and magnetic fluid based all-fiber optic current sensor, which can be interrogated by monitoring the dip wavelength shift or transmission loss of the transmission spectrum, is designed. For the first interrogation method, the current sensitivity of 1243.7 pm/A [77.9 pm/Oe, 1 Oe=1/(4π)×103 A/m] is obtained. For the second way, the sensing property depends on wavelength. By analyzing the rule of the change of transmission loss under different wavelengths, it is found that when a specified wavelength is used, the sensing property is influenced by different wavelengths and the variation of transmission loss is little, leading to a small sensitivity. When the all transmission loss during broad wavelength range of source is employed, the change of transmission loss is obvious, and hence the current sensitivity is greatly enhanced. The obtained sensitivity of 506.2 dB/A (31.7 dB/Oe) is 337 times and 723 times larger than those under 1529 nm and 1611 nm, respectively. Furthermore, the sensitivity of 26.8 V/A (1.7 V/Oe) is achieved by detecting the output intensity using detector with amplified spontaneous emission broadband light source inputting..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 705003 (2014)
Research Article
Research of Stochastic Parallel Gradient Descent Algorithm Based on Segmentation Random Disturbance Amplitude
Wu Jian, Yang Huizhen, and Gong Chenglong
The improved method of random perturbance amplitude section is proposed to increase the convergence speed of stochastic parallel gradient descent (SPGD) algorithm. The SPGD algorithm convergence rate, which can be effected by the random disturbance amplitude, is analyzed when the gain coefficient is fixed. The segmentaThe improved method of random perturbance amplitude section is proposed to increase the convergence speed of stochastic parallel gradient descent (SPGD) algorithm. The SPGD algorithm convergence rate, which can be effected by the random disturbance amplitude, is analyzed when the gain coefficient is fixed. The segmentation random perturbance amplitude method is put forward. The adaptive optics system without wavefront sensor is built with a 61-element deformation mirror to correct the wavefront aberrations, which is simulated by the 65-order Zernike polynomials and the aberrations meet the Kolmogorov spectrum. Compared with the best fixed initial perturbance amplitude SPGD algorithm, the convergence speed increases 1.6 times by adopting the SPGD algorithm based on the segmentation random perturbance amplitude. The improved algorithm is verified to be feasible..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 712001 (2014)
New Methods of Signal-Induced Noise Deduction for Rayleigh Scattering Lidar in Temperature Measurement
Guan Sai, Yang Guotao, Cheng Xuewu, Chang Qihai, Yang Yong, Yue Chuan, and Gong Shaohua
A new grounded precious experimental method is proposed for identifying signal-induced noise (SIN) originated in the photoelectric detector, as well as establishing a fine structure SIN model for its deduction from raw Lidar signals. The method of data process of a dual-wavelength Rayleigh scattering lidar with multi-cA new grounded precious experimental method is proposed for identifying signal-induced noise (SIN) originated in the photoelectric detector, as well as establishing a fine structure SIN model for its deduction from raw Lidar signals. The method of data process of a dual-wavelength Rayleigh scattering lidar with multi-channels enrolled in the meridian project is improved. Temperature profiles obtained by calibrated data show the coincident distribution with the TIMED satellite over the altitudes of 35 km to 85 km, temperature bias between them is less than 5 K from 30 km to 55 km, less than 10 K from 55km to 75 km..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 713001 (2014)
Biomedical Photonics and Laser Medicine
High-Speed Three-Dimensional Swept Source Optical Coherence Tomography System Based on LabVIEW
Wang Ling, Zhu Hailong, Tu Pei, and Wu Kaihua
The self-developed high-speed three-dimensional swept optical coherence tomography (SS-OCT) system is reported. Based on fast swept laser technology, the system can realize high speed axial scan (A-scan) rate of 50 KHz. In order to shorten the development cycle, the system software is based on LabVIEW combining with MaThe self-developed high-speed three-dimensional swept optical coherence tomography (SS-OCT) system is reported. Based on fast swept laser technology, the system can realize high speed axial scan (A-scan) rate of 50 KHz. In order to shorten the development cycle, the system software is based on LabVIEW combining with Matlab. Which achieves modular design including timing control, data acquisition, data processing and image reconstruction. The system has a friendly interface and is easy to maintain. It utilizes an external clock uniform in K-space as triggers synchronously generated by the swept source—a K-trigger mode for data acquisition so that a uniform data sampling in K-space is enabled without any other linear wavenumber re-calibracation. Actually measured axial resolution of the system is 8.9 μm. The systerm sensitivity is experimentally determined to be above 100 dB in the whole depth range. This SS-OCT systerm is capable of realtime display of two-dimensional OCT and can obtain three-dimensional OCT with a measurement time of 1.8 s. Vivo human finger segments and apple peel tissue are investigated two- and three-dimensionally. The three-dimensional OCT volumes chearly show the structures of the fingerprint which are difficult to be observed in two-dimensional OCT images..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 704001 (2014)
Laser Devices and Laser Physics
Spatial-Domain Computer Generated Holographic Three-Dimensional Display
Dong Jianwen, Chen Dingchen, Pang Xiaoning, Liu Yuanzhi, and Xu Zongxi
Three-dimensional (3D) display has been made great progress in recent years due to the development of the fields on optical information and computer science technologies. Holography enables to provide accurate depth cues of 3D objects and has attracted much attention. Computer generated hologram (CGH) is one of the excThree-dimensional (3D) display has been made great progress in recent years due to the development of the fields on optical information and computer science technologies. Holography enables to provide accurate depth cues of 3D objects and has attracted much attention. Computer generated hologram (CGH) is one of the exceptional way to utilize vivid 3D scene of both virtual and real objects. However, time-consuming holographic computation and ultra-narrow viewing angle are two main disadvantages. The provement on the computer Fraunhofer formulism in Fresnel region is reviewed. Spatial-domain Fraunhofer CGH algorithm, a method, which is used to generate hologram of polygon-based 3D model is systematically introduced. Based on this method, the problems on occlusion, shading, and texture are solved. Also a 4f optical system by time division multiplexing and spatial tiling technique is reviewed. This method can be used in the computation of other complicated 3D scenes with large amounts of data, which is helpful to the development of holographic display..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 701001 (2014)
Laser Manufacturing
[in Chinese]
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Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 702003 (2014)
Splicing Technology of Fiber Large Diameter End-Cap Based on CO2 Laser
Zhang Zhiyan, Niu Ben, Gao Wenyan, Hou Wei, and Lin Xuechun
Fiber large diameter end-cap splicing is one of the key technologies to increase energy transfer in fiber up to kilowatt. In order to achieve fiber large diameter end-cap splicing, the splicing mechanism of fiber end-cap is analyzed theoretically. A system of fiber end-cap splicing is designed and built based on CO2 laFiber large diameter end-cap splicing is one of the key technologies to increase energy transfer in fiber up to kilowatt. In order to achieve fiber large diameter end-cap splicing, the splicing mechanism of fiber end-cap is analyzed theoretically. A system of fiber end-cap splicing is designed and built based on CO2 laser, and the method and processing of fiber large diameter end-cap splicing are investigated and implemented. The continuous wave laser up to kilowatt is transferred successfully by the fiber that is with spliced large diameter end-cap..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 703001 (2014)
Effects of Scanning Patterns on the Thermal/Stress Field during Laser Solid Forming T-Shape Chord of Ti-6Al-4V Alloy
Jiang Yaqiong, Lin Xin, Ma Liang, Tan Hua, Yang Haiou, and Huang Weidong
Finite-element models of the thermal/stress field for three different scanning patterns, i.e. contour offsetting, long raster and short raster patterns, during laser solid forming (LSF) processes for T-shaped chord of Ti-6Al-4V alloy are developed respectively. It is shown that the component along the vertical directioFinite-element models of the thermal/stress field for three different scanning patterns, i.e. contour offsetting, long raster and short raster patterns, during laser solid forming (LSF) processes for T-shaped chord of Ti-6Al-4V alloy are developed respectively. It is shown that the component along the vertical direction GYmax of the maximum temperature gradients in the melting pool is much bigger than its component along the scanning direction GXmax. Both GYmax and GXmax decrease in first few layers and then become almost constant with the increase of cladding height. Finally GYmax is about three times as great as GXmax. The instantaneous maximum temperature gradient GTmax for short raster pattern always presents a fluctuation with a small amplitude range and which is smaller than those for other patterns as a whole. The increasing velocity of stress for long raster pattern is somewhat larger than that for contour offsetting, the increasing velocity of stress for short raster pattern is the smallest. When the deposition of the T-shape chords are finished, there exists a residual stress concentration at the back of conjunction of horizontal and vertical parts of the T-shape chord for contour offsetting pattern, at the two ends of the chord for long raster pattern. And the residual stress distribution in T-shape chord formed by short raster pattern is uniform. The residual stresses in different directions on the substrate for these three scanning patterns show the same distribution regularity, but the residual stress of short raster is smaller than others..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 703003 (2014)
Experiment of Laser Melting-Forming for PMMA Microstructure Parts
Tan Wensheng, Zhou Jianzhong, Huang Shu, Zhu Weili, and Men Xiankai
In order to realize molding process of polymethyl methacrylate (PMMA) micro-structured parts with high efficiency and high precision, a new molding method is presented with laser melting. This paper develops fabrication and experiment devices,and carry out the experiment of laser melting-molding on PMMA microstructuresIn order to realize molding process of polymethyl methacrylate (PMMA) micro-structured parts with high efficiency and high precision, a new molding method is presented with laser melting. This paper develops fabrication and experiment devices,and carry out the experiment of laser melting-molding on PMMA microstructures by CO2 laser scanning. According to thermal physics and energy conservation the temperature variation of samples is analyzed with the method of numerical analysis and simulation, and the effects of the various processing parameters on replication quality are investigated via orthogonal experiment. The results show that the temperature of the melt is the main factor affecting the quality of the molding, where high temperature leads to a good molding precision. Laser power is the decisive parameter to influence the replication precision of the micro-structure; scanning time and mould temperature are the secondary factors; molding pressure is the least important among them. At last, the molding process of PMMA microstructure with good replication precision is obtained by optimized process. It is demonstrated that the proposed process is a feasible and effective way to laser melting-molding PMMA micro-structured parts..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 703009 (2014)
High Volume Fraction and Length-Diameter Ratio of TiB Short Fiber and TiB2P Reinforce Ti-Based Alloy Composite Coatings by Laser Synthesis In-Situ
Lin Yinghua, and Lei Yongping
Preset layering powder containing Ti+TiB2P, coarse TiB2P and fine TiB2P are taken to prepare TiB short fiber, with reinforcing Ti-based composite coatings on the surface of Ti6Al4V through laser synthesis in-situ. Volume fraction and length-diameter ratio of TiB short fiber are analyzed by scan electron microscopy (SEMPreset layering powder containing Ti+TiB2P, coarse TiB2P and fine TiB2P are taken to prepare TiB short fiber, with reinforcing Ti-based composite coatings on the surface of Ti6Al4V through laser synthesis in-situ. Volume fraction and length-diameter ratio of TiB short fiber are analyzed by scan electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the coating is mainly composed of TiB short fiber and TiB2P. When Ti+TiB2P acts as a preset layer, length-diameter ratio of TiB short fiber reduces as the content of Ti increases; when coarse TiB2P acts as a preset layer, the coating is difficult to form a large volume fraction of TiB short fibers; when fine TiB2P acts as a preset layer, high volume fraction and large length-diameter ratio of TiB short fiber can be formed in the coating. The formation mechanism is explained through microstructure evolvement rule of TiB short fiber in the coating..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 703010 (2014)
Experimental Investigation on Warm Micro-Forming by Laser-Driven Flyer
Liu Huixia, Zhang Qiang, Gu Chunxing, Shen Zongbao, Ma Youjuan, Gu Yuxuan, and Wang Xiao
In this paper, the laser-driven flyer warm micro-forming method is proposed. Warm forming experiments are carried out using YdYAG laser with wavelength of 1064 nm and 3D morphology of formed T2 copper parts are observed. The influence of temperature (25 ℃, 100 ℃, 150 ℃, 200 ℃) and laser energy (1020, 1380, 1690, 1900 mIn this paper, the laser-driven flyer warm micro-forming method is proposed. Warm forming experiments are carried out using YdYAG laser with wavelength of 1064 nm and 3D morphology of formed T2 copper parts are observed. The influence of temperature (25 ℃, 100 ℃, 150 ℃, 200 ℃) and laser energy (1020, 1380, 1690, 1900 mJ) on the forming depth are analyzed. Hardness variation of the formed parts in forming regions is studied using nanoindentation and the forming mechanism is preliminary analyzed. It is found that better comprehensive performance during the plastic deformation is obtained by the laser-driven flyer warm micro-forming method: not only warm formability can be improved but also the hardness can be improved properly in forming regions. It is concluded that the laser-driven flyer warm micro-forming results from the competitive effects of both the laser shock peening mechanism and temperature soften mechanism..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 703011 (2014)
Influence of Temperature Distribution of Ceramic Coating Using Top-Hat Assistant Laser Beam in Dual-Beam Laser Cladding
Wu Dongjiang, Chu Yang, Niu Fangyong, Ma Guangyi, and Zhuang Juan
Thermal stress caused by oversized temperature gradient in the process of laser cladding ceramic coating on metal substrate usually makes the coating cracked. Reducing the temperature gradient of the laser cladding process can reduce the thermal stress to a certain degree to suppress the generation of cracks. Through nThermal stress caused by oversized temperature gradient in the process of laser cladding ceramic coating on metal substrate usually makes the coating cracked. Reducing the temperature gradient of the laser cladding process can reduce the thermal stress to a certain degree to suppress the generation of cracks. Through numerical simulation of temperature distribution during laser cladding Al2O3 coating on Ti6Al4V substrate, a method of providing preheating and slow-cooling using top hat laser beam is proposed. Temperature distribution and temperature gradient of the coating with preheating and slow-cooling are discussed by changing the spot size and power density of the top hat assistant laser beam. The results show that there is a significant feature of preheating and slow-cooling during the cladding process, the top hat assistant laser beam can reduce the temperature gradient effectively. The temperature gradient of the plastic point (1533 K) of Al2O3 reduces while the preheating and slow-cooling temperature raises. But the temperature gradient of the plastic point will rebound when the preheating and slow-cooling temperature is near the plastic point. Higher preheating and slow-cooling temperature make the cladding process better, but temperature around the plastic point should be avoided..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 703012 (2014)
Laser Physics
Theoretical Research on Characteristics of the Gains in Nickel-Like Krypton 32.8 nm Laser System
Zhao Yongpeng, Jiang Shuisen, Ding Yujie, Li Lianbo, Cui Huaiyu, and Jiang Shan
In order to study the plasma state for Ni-like Kr 32.8 nm laser, the atomic parameters of the Ni-like Kr 32.8 nm laser system are calculated with Cowan physical code. Based on the level parameters, the rate equations of energy level are established and solved under the quasi-steady-state approximation. The relative popIn order to study the plasma state for Ni-like Kr 32.8 nm laser, the atomic parameters of the Ni-like Kr 32.8 nm laser system are calculated with Cowan physical code. Based on the level parameters, the rate equations of energy level are established and solved under the quasi-steady-state approximation. The relative population density and the relative gain coefficient between the upper and lower levels of the laser are calculated with different electron temperatures and electron densities. The influence of the sub-levels of 3d94p, 3d94d and 3d94f configurations on laser generation is analyzed as well. The optimum plasma state for Ni-like Kr 32.8 nm laser generation is obtained through theoretical calculation. The best electron temperature is about 75 eV and the optimum electron density is about 1018 cm-3. These calculation results provide theoretical foundation for the experiment of Ni-like Kr 32.8 nm laser pumped by capillary discharge in the future..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 702001 (2014)
High Efficient Production of 1.053 μm Pico-Second Raman Laser Excited by Ti:Sapphire Laser
Wang Zhihua, Gong Liji, Liu Jie, Wang Yajing, Xu Liping, and Luo Shirong
A high efficient conversion from the Ti: Sapphire laser to the Raman laser with 1053 nm wavelength at the area of picosecond (ps) pulse duration is reported. A Ti:Sapphire laser (808 nm wavelength,450 ps pulse duration and 10 mJ pump energy) is employed as the pump source, acetone is stimulated to generate first-order A high efficient conversion from the Ti: Sapphire laser to the Raman laser with 1053 nm wavelength at the area of picosecond (ps) pulse duration is reported. A Ti:Sapphire laser (808 nm wavelength,450 ps pulse duration and 10 mJ pump energy) is employed as the pump source, acetone is stimulated to generate first-order Stokes wave with 1053 nm central wavelength. Inserting Ndglass as a fluorescence enhancement medium, the first-order Stokes wave is obviously enhanced, the energy conversion efficiency from pump laser to the first-order Stokes wave reaches to 17.5％, the bandwidth of the first-order Stokes is 25 nm, and the pulse duration is 318 ps. The physical mechanism together with the potential applications are discussed..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 702002 (2014)
Efficient Continuous Diode-Pumped Nd:YVO4 Slab Laser with an Opened-Loop Reciprocal Dynamic Holographic Cavity
Sun Zhe, Li Qiang, Cheng Qiutong, Jiang Menghua, Lei Hong, and Hui Yongling
A self-adaptive laser based on a diode bar side pumped Nd:YVO4 slab with opened-loop reciprocal cavity completed by dynamic holographic gratings is created. The output power, optical-to-optical efficiency, frequency spectrum and spatial characteristics of the generated beam are examined. Compared with similar structureA self-adaptive laser based on a diode bar side pumped Nd:YVO4 slab with opened-loop reciprocal cavity completed by dynamic holographic gratings is created. The output power, optical-to-optical efficiency, frequency spectrum and spatial characteristics of the generated beam are examined. Compared with similar structure of traditional laser oscillator, the holographic gratings are exist in the opened-loop reciprocal cavity and the obvious modulation of the transverse mode and longitudinal mode is observed. A high spatial quality beam (M2<1.2) with up to 18.25 W average power, 48% optical-to-optical efficiency, and 10001 extinction ratio is obtained..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 702003 (2014)
Temporal and Spatial Characteristics of Ultrashort Pulse Propagation in Turbid Media
Jin Sai, Tan Wenjiang, Liu Xin, Wu Bin, and Si Jinhai
The Monte Carlo method is introduced to simulate and analyze the influence of optical parameters of the turbid medium, such as anisotropy factor, on the temporal and spatial distributions and scattering-order distributions of ultrashort pulses. The result shows that when anisotropy factor or absorption coefficient decrThe Monte Carlo method is introduced to simulate and analyze the influence of optical parameters of the turbid medium, such as anisotropy factor, on the temporal and spatial distributions and scattering-order distributions of ultrashort pulses. The result shows that when anisotropy factor or absorption coefficient decrease and scattering coefficient or propagation depth increase, both of the pulse duration and the beam size broaden and the proportion of scattering photons at high scattering orders increase..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 702004 (2014)
Frequency Stabilization of Mid-Infrared Difference Frequency Laser by Iodine Molecule Absorption
Sun Mingguo, Ma Hongliang, Wang Guishi, Wang Lei, Cao Zhensong, Liang Wanguo, Chen Huaixi, Zhou Huang, Zou Xiaolin, Chen Weidong, and Gao Xiaoming
Difference frequency laser used for the study of atmospheric molecule isotope abundance requires stable frequency and continuous idler radiation. A difference frequency generation (DFG) system is established based on a tunable continuous wave (CW) Tisapphire laser and a CW single-frequency NdYAG laser. In the DFG systeDifference frequency laser used for the study of atmospheric molecule isotope abundance requires stable frequency and continuous idler radiation. A difference frequency generation (DFG) system is established based on a tunable continuous wave (CW) Tisapphire laser and a CW single-frequency NdYAG laser. In the DFG system, frequency stabilization method of iodine molecule Doppler-broadened absorption combined with digital proportion integration differentiation (PID) feedback control technology is adopted to stabilize the wavelength of infrared laser arised from the DFG system, while MgOPPLN is used as the frequency doubling crystal. The NdYAG laser frequency shift is stabilized within 1.2 MHz/h and the stability is 4.26×10-9. The experimental results show that the frequency shift within 1 h of NdYAG laser decreases rapidly with the increase of the voltage loaded on piezoelectric ceramic (PZT), but smaller shift is not achieved beyond 1 V; better stability is not achieved by changing the frequency of modulation voltage. NdYAG laser with stabilized frequency is used to generate difference frequency laser near 3.42 μm. By detecting low pressure absorption line of CH4, the 6.9 MHz line width of this difference frequency system is derived. The results provide not only an important reference for laser frequency stabilization by this technology, but also a stable difference frequency laser for trace gas detection..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 702006 (2014)
Effect of Splitting Ratio on the Inversion of Wind in the Dual Edge Rayleigh Wind Measurement Technology
Shangguan Mingjia, Xia Haiyun, Shu Zhifeng, Sun Dongsong, Zhang Feifei, Hu Dongdong, Han Yuli, and Gao Yuanyuan
Theoretical analysis shows that splitting ratio of signal paths affects the accuracy of wind speed measurement in dual edge Rayleigh wind measurement technology. Therefore, the splitting error should be calculated when evaluating the wind speed error, and one suitable spectroscopic instrument should be selected as muchTheoretical analysis shows that splitting ratio of signal paths affects the accuracy of wind speed measurement in dual edge Rayleigh wind measurement technology. Therefore, the splitting error should be calculated when evaluating the wind speed error, and one suitable spectroscopic instrument should be selected as much as possible. Multimode optical fiber beamsplitter and beamsplitter are usually used in lidar. As for beamsplitter, its splitting ratio is affected by the depolarization of the atmosphere. As for the multimode optical fiber beamsplitter, its splitting ratio is affected by the measurement error. According to the analysis, the range of relative beamsplitter change is from 0.07% to 0.63% due to depolarization effects in pure molecular scattering environment. However, the mean value of multimode optical fiber beamsplitter is 1.018, and the standard deviation is 0.4%. Therefore, multimode optical fiber beamsplitter is used in lidar. Finally, the Rayleigh Doppler lidar combined with balloon wind test, the test results show the wind field in good agreement..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 714001 (2014)
Materials and Thin Films
Fabrication and Properties of Au/Ag Core/Shell Nanostructures Prepared by Laser Ablation in Liquid Solutions
Li Shuanghao, and Zhao Yan
A new method of synthesis Au/Ag core/shell nanostructure with KrF excimer laser is studied. It is found that the Au/Ag core/shell nanostructures with spherical shell can be prepared by KrF excimer laser which is obviously confirmed by high resolution transmission electron microscopy (HRTEM). The surface plasma resonancA new method of synthesis Au/Ag core/shell nanostructure with KrF excimer laser is studied. It is found that the Au/Ag core/shell nanostructures with spherical shell can be prepared by KrF excimer laser which is obviously confirmed by high resolution transmission electron microscopy (HRTEM). The surface plasma resonance (SPR) of this nanostructure can be tuned by controlling thickness of the Ag shell. Simulation based on Mie theory is in agreement with the result of the experiments. Moreover, it is indicated that the Au/Ag core/shell nanostructure has excellent activity in surface-enhanced Raman scattering (SERS). This Au/Ag core/shell nanostructure may be applied to high sensitive trace detection in the future..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 706001 (2014)
Substrate Effects on the Water Absorption of Infrared SiO2 Film
Li Hao, Yi Kui, Cui Yun, and Fan Zhengxiu
SiO2 films are deposited on Al2O3、 JGS3 and Si substrate by electron beam technology. In-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and atomic force microscope (AFM) tests are used to demonstrate the relationship between the water absorption and the microstructure of the SiO2 films. The iSiO2 films are deposited on Al2O3、 JGS3 and Si substrate by electron beam technology. In-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and atomic force microscope (AFM) tests are used to demonstrate the relationship between the water absorption and the microstructure of the SiO2 films. The in-situ DRIFTS and AFM results indicate that the water absorption is enhanced while number of pores on the film surface increased. The peaks of absorption center is determined by the surface roughness of the films. Blue-shifted of absorption are evidently observed while the temperature increased from 25 ℃ to 220 ℃..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 707001 (2014)
Super-Resolution Effect of Sb80Bi20 Optical Nonlinearity Nanofilms
Zhai Fengxiao, Zhang Kui, Wang Yang, and Wu Yiqun
A Z-scan system is employed to investigate optical nonlinearity of Bi20Sb80 thin films under low laser intensity. Optical constants and ellipsometric parameters are measured by spectroscopic ellipsometry. Experimental results indicate that Sb80Bi20 films show giant nonlinear saturated absorption. The nonlinear absorptiA Z-scan system is employed to investigate optical nonlinearity of Bi20Sb80 thin films under low laser intensity. Optical constants and ellipsometric parameters are measured by spectroscopic ellipsometry. Experimental results indicate that Sb80Bi20 films show giant nonlinear saturated absorption. The nonlinear absorption coefficient is about -0.018 m/W. However, there is no appreciable nonlinear refraction effect in measurement. The giant nonlinear saturated absorption is dominant response for super-resolution effect. The calculation result indicates that the squeezed half width of Gaussian spot with about 10% can be achieved in Sb80Bi20 films with thickness of 35 nm. The Sb80Bi20 nanofilms are shown to be very promising for super-resolution applications..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 707002 (2014)
Measurement and Metrology
Optimal Layout of Three-Dimensional Coordinate Measurement System Based on Laser Multi-Lateration
Hu Jinzhong, Yu Xiaofen, Ren Xing, and Zhao Da
The measurement accuracy of the three-dimensional (3D) coordinate measuring system based on laser multi-lateration is influenced by its layout. In previous study, the system′s layout is optimized for the tri-rectangular pyramid layout by theoretical analysis of the non-target self-calibration model. On this basis, throThe measurement accuracy of the three-dimensional (3D) coordinate measuring system based on laser multi-lateration is influenced by its layout. In previous study, the system′s layout is optimized for the tri-rectangular pyramid layout by theoretical analysis of the non-target self-calibration model. On this basis, through error analysis of the linearized measurement model of the system, it is found that the optimal layout, that is the tri-rectangular regular pyramid layout, is obtained, when the condition number of the coefficient matrix of the measurement model achieves minimum. Simulation results show that the tri-rectangular regular pyramid layout can efficiently ensure the accuracy of the system..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 708001 (2014)
Simultaneous Determination of Spot Size of Focused Laser Beam on Focal Plane and Laser-Ablation Thresholds of Samples
Mo Junyu, Chen Yuqi, Zhou Qi, and Li Runhua
The function of laser pulse energy to the radius of the crater produced by focused laser beam on sample′s surface is derived theoretically under the condition that the fluency distribution of the focused laser beam on the focal plane is Gaussian shape. An aluminum foil, an aluminum reflection mirror and a piece of therThe function of laser pulse energy to the radius of the crater produced by focused laser beam on sample′s surface is derived theoretically under the condition that the fluency distribution of the focused laser beam on the focal plane is Gaussian shape. An aluminum foil, an aluminum reflection mirror and a piece of thermo-sensitive photographic paper are used as samples and the radii of the craters produced by laser beam with different pulse energies on sample′s surfaces are measured with a microscope. The spot size of focused laser beam on the focal plane and the laser-ablation threshold of the sample are measured simultaneously by curve fitting. The laser-ablation thresholds of aluminum and thermo-sensitive photographic paper for 532 nm laser pulse with 15 ns pulse width are determined to be 2.5 J/cm2 and 0.25 J/cm2, respectively. Measurement errors for both spot size and laser-ablation threshold are about ±10%. It is demonstrated that the approach introduced here is able to determine spot size of the focused laser beam on the focal plane and the laser-ablation threshold of the sample conveniently and simultaneously. It is able to be used in researches on laser interaction with solid materials and to evaluate the characterization of a focused laser beam..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 708003 (2014)
Impact of Wavelet Function Frequency Sidelobe on the Effect of Three-Dimensional Reconstruction
Xu Luopeng, Dan Youquan, An Kang, Yang Fanrong, Wang Xiaopeng, Chen Yu, and Wang Qingyuan
Based on continuous wavelet transform (CWT) in three-dimensional surface reconstruction, the result of reconstruction often depends on the choice of wavelet function. The performance of wavelet function′s spatial and frequency domain determines the efficiency and effectiveness of data process. Different wavelet functioBased on continuous wavelet transform (CWT) in three-dimensional surface reconstruction, the result of reconstruction often depends on the choice of wavelet function. The performance of wavelet function′s spatial and frequency domain determines the efficiency and effectiveness of data process. Different wavelet function itself has different performance, which usually exits different sidelobes in frequency domain. This paper discusses the impact of complex Gauss series wavelets′ frequency sidelobes in three-dimensional shape reconstruction. The calculation results show that frequency sidelobes have a smaller trend with the increase order of complex Gauss wavelet function differential.Meanwhile, theoretical analysis and experiments give the same results in local analysis abilities. In order to illustrate the frequency sidelobe question, complex Morlet wavelet and Mexican hat wavelet function are used to verify this regularity. The experimental results agree well with the theoretical analysis..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 708005 (2014)
Prediction Method and Measurement of the Depth of Subsurface Damage of Glass-Ceramic by Lapping Process
Xiang Yong, Ren Jie, Bai Manshe, Chen Jing, and Zhang Jinkuan
The process of abrasive machining in lapping is considered as a moving sharp indentor subjected to normal force and tangential force. Based on indentation fracture mechanics theory, the grinding stresses of material, the location of median crack initiation and the direction of median crack propagation beneath an abrasiThe process of abrasive machining in lapping is considered as a moving sharp indentor subjected to normal force and tangential force. Based on indentation fracture mechanics theory, the grinding stresses of material, the location of median crack initiation and the direction of median crack propagation beneath an abrasive are analyzed. The calculation formula of median crack propagation length is analyzed by synthetically considering the contribution of elastic stress field, residual stress field and tangential force beneath the abrasive. A theoretical model of relationship between subsurface damage and surface roughness is established. A method of magnetorheological finishing (MRF) spot technique is proposed to the depth of subsurface damage. Predicted results are compared with experimental results, result shows that the error between predicted results and experimental results is less than 5.56%. The theoretical model can be used for prediction the depth of subsurface damage of optical materials in lapping process rapidly, expediently and accurately..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 708006 (2014)
Absolute Testing of Rotationally Asymmetric Surface Deviation with the Method of Rotation-Averaging and Compensation
Zhang Yanwei, Su Dongqi, Sui Yongxin, and Yang Huaijiang
The rotation method is an absolute testing to obtain rotationally asymmetric surface. A compensation method based on rotation-averaging needs a different rotation measurement besides N equally spaced azimuthal measurements, which is called N+1 rotation method. The losing surface of rotation-averaging method can be obtaThe rotation method is an absolute testing to obtain rotationally asymmetric surface. A compensation method based on rotation-averaging needs a different rotation measurement besides N equally spaced azimuthal measurements, which is called N+1 rotation method. The losing surface of rotation-averaging method can be obtained with the additional measurement data and Zernike polynomial fitting. The theoretical formulas are derived and the validity of compensation method is simulated. The impact of additional rotation angle on algorithm accuracy is presented. The experimental result is consistent with simulation very well which proves that the losing surface can be compensated effectively by this method with an appropriate angle. Compared with the rotation-averaging method, this method can greatly improve the testing efficiency and accuracy by just adding one additional measurement. The compensation ratio is 0.61 and the accuracy is improved by a factor of 1..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 708007 (2014)
Optical Communication
Microwave Signal Generation Based on Dual-Wavelength Brillouin Fiber Laser
Jia Qingsong, Wang Tianshu, Zhang Peng, Sun hongwei, Dong Keyan, Liu Xin, Kong Mei, and Jiang Huilin
A simple approach to generate stable microwave signals by heterodyning pump light and Stokes lasing light from a dual-wavelength Brillouin fiber laser (BFL) is proposed and demonstrated. Stable dual-wavelength output is obtained by adjusting two polarization controllers. A microwave signal is observed and the central fA simple approach to generate stable microwave signals by heterodyning pump light and Stokes lasing light from a dual-wavelength Brillouin fiber laser (BFL) is proposed and demonstrated. Stable dual-wavelength output is obtained by adjusting two polarization controllers. A microwave signal is observed and the central frequency of the microwave signal is around 10.75 GHz. A segment of 10 km-long single-mode fiber (SMF) is used as Brillouin gain, and a 4 m long unpumped polarization maintaining erbium-doped fiber (PM-EDF) and micro-ring cavity, which is composed of 2×2 3 dB coupler, suppress unwanted side-modes. A distributed feedback (DFB) semiconductor laser is used as the Brillouin pump (BP). The output of dual-wavelength fiber laser is injected into a optoelectric detecter (PD) with a bandwidth of 50 GHz. An electrial spectrum analyzer (ESA) is used to measure the microwave signal around 10.75 GHz. Linewidth of the microwave signal is around 600 kHz..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 705001 (2014)
Wavelength-Preserving All-Optical Regenerative Scheme for Satellite Based on Two-Stage Offset Filtering
Dong Yi, Zhao Shanghong, Zhang Xiaoyan, Zheng Xiaomei, Dong Chen, and Zhu Zihang
Aiming at the dynamic routing characteristic of distributed satellite network, a wavelength-preserving all-optical regenerative scheme based on two-stage offset filtering is put forward. By using the property that the signs of chirp induced by self-phase modulation (SPM) are opposite in semiconductor optical amplifier Aiming at the dynamic routing characteristic of distributed satellite network, a wavelength-preserving all-optical regenerative scheme based on two-stage offset filtering is put forward. By using the property that the signs of chirp induced by self-phase modulation (SPM) are opposite in semiconductor optical amplifier (SOA) and high nonlinear fiber, a red-shifted filtering and a blue-shifted filtering are done respectively on the signals after the SOA and the HNLF, which not only realizes a two-stage regeneration of signals, but also compensates the frequency offset and keeps the wavelength unchanging before and after the regenerator. Meanwhile, the scheme is of simple structure, small volume and light quality, which can satisfy the limitation of satellite to the payloads. The result shows that the Q factor of signals can be improved more than 1.5 dB, and the bit error rate (BER) can be reduced more than one order of magnitude compared with the result of one-stage regenerator..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 705002 (2014)
Research on Damage on Transparent Electro-Optic Ceramic Surface Induced by Nanosecond and Femtosecond Pulses
Zhang Xuejiao, Ye Qing, Qu Ronghui, and Cai Haiwen
Damage morphologies on lanthanum doped lead zirconate titanate (PLZT) surface induced by nanosecond and femtosecond pulses irradiate. Different levels of the high power nanosecond and femtosecond pulses are irradiation on the surface of PLZT, where the pulses are near Gaussian beams. The damage probability is observed Damage morphologies on lanthanum doped lead zirconate titanate (PLZT) surface induced by nanosecond and femtosecond pulses irradiate. Different levels of the high power nanosecond and femtosecond pulses are irradiation on the surface of PLZT, where the pulses are near Gaussian beams. The damage probability is observed on line and the suitable powers of the pulses are adjusted. The nanosecond pulse induced damage threshold of PLZT is 485 MW/cm2. The variations of the damage spot diameters versus the energy irradiation are analyzed. The variation of the damage depth versus the damage diameters and the damage morphology induced in the defect in the ceramic are also detected and recorded. The damage morphologies induced by nanosecond and femtosecond pulses are also contrasted. And some possible explanations due to the difference are given..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 706002 (2014)
COHERENCE OPTICS and STATISTICAL OPTICS
Microstructure and TiC Evolution Behavior of TiC/Fe3Al Composite Coating Fabricated by Laser Surface Alloying
Pu Fei, Liu Yuanfu, Xu Xiangyang, Peng Yanbo, and Zhang Longhua
TiC reinforced Fe3Al intermetallic matrix composite coating is fabricated on 0.2% C carbon steel substrate by laser surface alloying with Al-TiC powders blend as the precursor material. The phases composition and microstructure of the composite coating are investigated by X-ray diffractometer (XRD), scanning electron mTiC reinforced Fe3Al intermetallic matrix composite coating is fabricated on 0.2% C carbon steel substrate by laser surface alloying with Al-TiC powders blend as the precursor material. The phases composition and microstructure of the composite coating are investigated by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). Through thermodynamic calculating, the dissolution thermodynamic conditions of TiC are confirmed. The dissolution and precipitation behavior of TiC phase are discussed. Results show that the coating mainly consists of Fe3Al and TiC. During the laser surface alloying process, when the temperature reaches 2000 K～2200 K, the TiC powders used as the precursor material begin to dissolve into the Fe-Al alloy melt, as in-situ reinforcement particles re-precipitate from the melt and are scattered with a net shape in the Fe3Al matrix..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 703002 (2014)
Research on Laser Ultrasound Imaging in Detection of Austenitic Stainless Steel Weld
Zeng Wei, Wang Haitao, Tian Guiyun, Wang Wen, Wang Xiao, and Hu Guoxing
A technique of laser ultrasonic imaging is proposed to detect austenitic stainless steel weld with artificical defects. Austenitic stainless steel weld is scanned using the pulse of NdYAG laser, and the received ultrasonic wave is transformed by discrete sine/cosine transform (DST/DCT) and Hilbert transform (HT). The cA technique of laser ultrasonic imaging is proposed to detect austenitic stainless steel weld with artificical defects. Austenitic stainless steel weld is scanned using the pulse of NdYAG laser, and the received ultrasonic wave is transformed by discrete sine/cosine transform (DST/DCT) and Hilbert transform (HT). The conventional ultrasound imaging method can not effectively detect the weld edge and the artificical defect, however, laser ultrasound imaging technology, which combines DST/DCT and HT, can not only directly and efficiently detect the weld edge, but can also detect the location, the shape and the size of damage in the weld. Therefore, the laser ultrasound imaging technology based on the discrete sine/cosine transform and Hilbert transform provides the basis for quantiative detection..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 703004 (2014)
Research on Parameter Selection of Pulsed Laser-Assisted Machining of Alumina Ceramics
Liu Weiqiao, Yan Cuo, Xie Linchun, Shi Ke, and Song Wei
Laser-assisted machining is one of the effective way to solve the problems that the hard and brittle materials are difficult to process. In order to study the influence of chosen processing parameters on the pulsed laser-assisted machining of Al2O3 ceramics, a heat conduction model is established to calculate the tempeLaser-assisted machining is one of the effective way to solve the problems that the hard and brittle materials are difficult to process. In order to study the influence of chosen processing parameters on the pulsed laser-assisted machining of Al2O3 ceramics, a heat conduction model is established to calculate the temperature field distribution of the workpiece under different parameter combinations. According to the softened layer size of Al2O3 ceramics where the temperature is 1000 K or above, appropriate cutting parameters are determined theoretically. Using related laser and cutting parameters obtained by the theoretical calculation, a cutting experiment is performed, removal rate is calculated, surface roughness and morphology of the workpiece are detected, and the relationship between the removal rate and the surface roughness is analyzed simultaneously. The results indicate that using the chosen processing parameters in accordance with the simulated temperature distribution ensures low surface roughness and high material removal rate during pulsed laser-assisted machining of Al2O3 ceramics. It also indicates that the selected parameters through temperature field simulation can effectively guarantee the requirements to process the hard and brittle materials..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 703005 (2014)
Process and Optimal Parameter Domain of Laser Marking Two-Dimension Code
Li Xiashuang, He Weiping, Lei Lei, Xu Yingfei, Song Baohua, and Tian Qinan
The correlation occurring between reading quality or marking time of data matrix (DM) code marked on aluminium alloy and laser marking parameters has been studied, and the influence of laser parameters on DM code contrast is analyzed. The experiment result indicates that the optimal laser parameter domain is not simplyThe correlation occurring between reading quality or marking time of data matrix (DM) code marked on aluminium alloy and laser marking parameters has been studied, and the influence of laser parameters on DM code contrast is analyzed. The experiment result indicates that the optimal laser parameter domain is not simply distributed within a connected real neighborhood, but distributed in a union set of several connected real neighborhoods. The restricted space of laser parameter based on reading quality of DM code is built, and the laser marking process parameters combination with the goal of comprehensive optimal reading quality and marking time is acquired based on this foundation. Meanwhile, scanning electron microscope images and energy dispersive spectrometer data of DM code marked by the optimal parameter module are analyzed, which can explain the distribution of optimal laser parameters in microcosm..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 703006 (2014)
Analytic Solution of Laser Irradiation Parameters for the Rolling Flying Target
Zhang Donglai, Li Xiaojiang, and Yang Yewei
The irradiation parameters are the foundation to study damage effect of flying target by laser, which include the location of irradiation center point, irradiation area and power density distribution. Taking the laser irradiating horizontal uniform moving target and parabolic moving target as the background respectivelThe irradiation parameters are the foundation to study damage effect of flying target by laser, which include the location of irradiation center point, irradiation area and power density distribution. Taking the laser irradiating horizontal uniform moving target and parabolic moving target as the background respectively, the assumed encounter scene and parameters are given. Then, the analytical calculation models of the location of irradiation center point, irradiation area and power density distribution are derived. The simulation results show that the irradiation parameters vary with the rolling and flying of target. The power density distribution in irradiation area is a varying three-dimensional elliptic Gaussian function. The rolling of target results in varying of location of irradiation center point and irradiation area, and influences temperature field of target and damage effect by laser. The analytical solutions are foundations for analyzing the effect of laser irradiating flying target..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 703007 (2014)
Microstructural Characteristics and Mechanical Properties of Pulsed Nd:YAG Laser Welded Copper and 316L Stainless Steel
Li Yang, Hu Shengsun, and Shen Junqi
A pulsed wave Nd:YAG laser is used to weld copper and 316L stainless steel. The microstructural characteristics and interfaces of the welded joints by different laser lap welding of copper and 316L stainless steel are investigated to search for the suitable welded joints and then analyze their mechanical properties. OpA pulsed wave Nd:YAG laser is used to weld copper and 316L stainless steel. The microstructural characteristics and interfaces of the welded joints by different laser lap welding of copper and 316L stainless steel are investigated to search for the suitable welded joints and then analyze their mechanical properties. Optical microscopy and energy dispersive spectroscopy (EDS) are used to observe the interface of the welded joints. X-ray diffraction (XRD) is used to analyze the phase of the interface. Scanning electron microscopy (SEM) is used to observe the fracture surface morphology of welded joint. Microhardness and tensile testing are used to analyze the mechanical properties of the welded joints. Results show that intermetallic compounds are absent in the welded joints because copper and stainless steel exhibit unlimited solid solubility. The welded joints with the copper on stainless steel overlap configuration show better microstructure and mechanical performance..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 703008 (2014)
Geometric Optics
Measuring Pulsed Laser Beam Divergence Angle Via Dual-Frame Image Fusion
Wang Jinsong, Zhu Dazhao, Li Yanfeng, and An Zhiyong
A method for measuring divergence angle of pulsed laser beam is proposed based on dual-frame image fusion and charge coupled device (CCD) characteristic that CCD camera response to illumination is nearly linearity in a certain range. The feasibility and accuracy are proved by experiment and mathematical simulation via A method for measuring divergence angle of pulsed laser beam is proposed based on dual-frame image fusion and charge coupled device (CCD) characteristic that CCD camera response to illumination is nearly linearity in a certain range. The feasibility and accuracy are proved by experiment and mathematical simulation via Matlab. This method expands the application scope of illuminance measured and makes up the defects that CCD dynamic response range is not wide, and is a good solution to the question that pulsed laser beam divergent angle measurement accuracy is not high. The experimental results show that measurement accuracy of this method is 2%..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 708002 (2014)
Research on Adaptive Width Measuring Method of Cut Tobacco and Its Application
Di Chengliang, Yan Wei, Hu Song, Zhao Weiyi, and Wen Ruoyu
The width of cut tobacco has significant influences on the physical properties and sensory qualities of cigarettes. Due to the narrowness, complex distribution and different widths properties of the cut tobacco, a width measuring method is proposed based on adaptive image processing technologies. The high definition imThe width of cut tobacco has significant influences on the physical properties and sensory qualities of cigarettes. Due to the narrowness, complex distribution and different widths properties of the cut tobacco, a width measuring method is proposed based on adaptive image processing technologies. The high definition image of cut tobacco is attained by the scanning of highly numerous pixel linear charge coupled device (CCD). Widths are measured by applying series of image processing courses, such as binarization, image segmentation, decontamination, refining, edge extraction and matrix turning. Applying this method on actual cut tobacco images, a well adaptability to the complex distribution of the cut tobacco is verified. Additionally, accuracy is confirmed by contrasting the measurement results with standard template that fabricated from E-Beam lithographic tools..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 708004 (2014)
Optical Design and Fabrication
Design of Optical Parametric Amplification Crystal Tiling Structure and Its Tiling Error Compensation
Yan Wei, Zhang Junwei, Wu Wenlong, Wang Xiao, Mu Jie, Li Zhilin, Su Jingqin, and Lin Donghui
Crystal tiling technology is a good way to solve the problem of nonlinear crystal aperture limit in the process of optical parametric chirped pulse amplification (OPCPA), which can improve the output ability of the amplifier effectively. To solve the problem of precise control of the phase matching angle and the crystaCrystal tiling technology is a good way to solve the problem of nonlinear crystal aperture limit in the process of optical parametric chirped pulse amplification (OPCPA), which can improve the output ability of the amplifier effectively. To solve the problem of precise control of the phase matching angle and the crystal machining error compensation in crystals tiling, a OPCPA crystal tiling method composing of the adjustsment independent and the error compensation is proposed. A 2×2 array crystal tiling adjustment structure and a 2×2 active array mirrors are designed. Each sub-crystal can be rotated three degrees of freedom to achieve the purposes of initial adjustment tiling angle and phase matching. 2×2 active array mirrors which are driven by nanometer accuracy piezoelectric actuators are used to compensate the cutting error of the tiling crystals. An experiment is conducted to test the feasibility and stability of the crystal tiling system using transmission elements and get good results. The result indicates that the crystal tiling technology is practical..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 716001 (2014)
Optical System Design of Large Entrance Pupil Catadioptric Star Sensor
Lü Bo, Liu Weiqi, Zhang Daliang, Jiang Shan, Kang Yusi, and Feng Rui
To develop the detection ability of ultimate stars, and use more dark stars as referenced stars of deep space aircraft navigation, a catadioptric star sensor with a proved Cassegrain configuration with three pieces of emending lens optical system is designed. In this system, the proved Cassegrain configuration is used To develop the detection ability of ultimate stars, and use more dark stars as referenced stars of deep space aircraft navigation, a catadioptric star sensor with a proved Cassegrain configuration with three pieces of emending lens optical system is designed. In this system, the proved Cassegrain configuration is used to reduce the spherical aberration and coma out of optical axis and bring the focus and large size of entrance pupil at the same time; emending lens close to the image plane is mainly eliminating the remaining aberrations of catoptric configuration, the telecentric image plane design among the emending configuration is also benefit to the irradiance unification in full of field and decrease the sensitivity of image sensor setting. This system has a 180 mm focal length and F-number is 2, view of field is 3°×3°, the effective pupil area is 5106 mm2, energy centroid aberration is smaller than 2.5 μm, lateral color is better than 3.5 μm among 450~800 nm spectrum, over 80% energy of spot in less than 3×3 pixel, and modulation transfer function (MTF) is approaching to diffraction limit. The inner baffles of reflected lens and outer two-group baffles are introduced, through modeling and analyzing the stray light of system in the Lighttools, the designed result shows that in the range of 2° to 40° incident angle of stray light, the point resource transmittance is between 10-6 to 10-4. These results can provide a good reference for further star sensors with deep space catadioptric configuration star sensor..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 716002 (2014)
Optical System Design of LCOS-Based and High Precision Dynamic Star Simulator
Chen Qimeng, Zhang Guoyu, Sun Xiangyang, Wang Guoming, and Wang Zhe
Aiming at completing functional tests on high precision star sensor of stars′ positional accuracy and star magnitude, an optical system of liquid crystal on silicon (LCOS)-based and high precision dynamic star simulator is designed. The general designing program is presented after the analysis of the collimating and thAiming at completing functional tests on high precision star sensor of stars′ positional accuracy and star magnitude, an optical system of liquid crystal on silicon (LCOS)-based and high precision dynamic star simulator is designed. The general designing program is presented after the analysis of the collimating and the illuminating optical system. In order to improve the simulating precision, a optical splicing method of LCOS is put forward, designing process of a collimating optical system with large field of view, large relative aperture and long exit pupil is given in detail as well as the aberration diagrams. To satisfy the illuminating conditions ordered by LCOS and achieve simulation of -1 to 7 magnitude stars, an illuminating optical system is emulated. Experimental test indicates that the angular distance accuracy is less than 12″, and -1 magnitude to 7 magnitude stars can be simulated, which meets the calibration requirements of high precision star sensor..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 716003 (2014)
Effect of Adjusting Force on Surface Figure of Lens in Eccentric Adjusting Mechanism
Zhang Defu, and Li Xianling
For aberration compensation requirement of projection objective lens in deep ultraviolet lithography, the stress analysis of the lens in eccentric adjusting is carried out. A kind of lens supporting with multi-flexure is designed based on compliance matrix method. Regularity between the adjusting force and the surface For aberration compensation requirement of projection objective lens in deep ultraviolet lithography, the stress analysis of the lens in eccentric adjusting is carried out. A kind of lens supporting with multi-flexure is designed based on compliance matrix method. Regularity between the adjusting force and the surface figure of the lens is investigated. Relationship among the adjusting force, the peak valley (PV) value, the root mean square (RMS) value and Fringe Zernike coefficients of the lens are analyzed using the finite element method. The results show that the aberration can be restricted by reducing the adjusting force. By using flexible support mechanism for absorbing adjusting force, the PV value and RMS value of the upper surface of the lens are 2.704 nm and 0.528 nm, the lower surface are 2.984 nm and 0.571 nm respectively in full stroke eccentric adjusting. The PV value, the RMS value and Fringe Zernike coefficients of the lens vary linearly with the adjusting force. The adjusting force does not change the nature of the aberration. The aberration is mainly astigmatism..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 716004 (2014)
Spectroscopy
Research on the Characteristics of Lead Contained in Lead Slime by Laser-Induced Breakdown Spectroscopy
Yu Yang, Zhao Nanjing, Wang Yin, Meng Deshuo, Hu Li, Zhang Dahai, Ma Mingjun, Liu Jianguo, and Liu Wenqing
The laser induced breakdown spectrum characteristic of lead contained in lead slime is studied with a 1064 nm wavelength NdYAG laser as the exitation source, a echelle spectrometer of high resolution and wide spectral range for spectral seperation and a intensified charge coupled device for high sensitive detection. ThThe laser induced breakdown spectrum characteristic of lead contained in lead slime is studied with a 1064 nm wavelength NdYAG laser as the exitation source, a echelle spectrometer of high resolution and wide spectral range for spectral seperation and a intensified charge coupled device for high sensitive detection. The characteristic spectrum line of PbⅠ405.78 nm is selected as the analytical line, the relationship of spectrum intensity and signal to noise ratio of PbⅠ405.78 nm varying with delay time and gate time are measured respectively. The optimum delay td=2.5 μs and gate tg=3.0 μs are confirmed. Under the approximation of local thermal equilibrium, 13 characteristic spectrum lines of Fe within the wavelength range of 360~441 nm are choosed, the temperature of plasma calculated by the means of Boltzmann diagram is 6934 K, and the electron density of plasma gained by using Lorentz fitting on PbⅠ405.78 nm is 8.3×1016 cm-3. These parameters provide a method and technical supports for fast quartitative analysis of lead sime..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 715001 (2014)
Quantitative Measurement of Cr in Soil Using Laser Induced Breakdown Spectroscopy Combined with Standard Addition Method
Meng Deshuo, Zhao Nanjing, Liu Wenqing, Fang Li, Ma Mingjun, Wang Yin, Yu Yang, Hu Li, Zhang Dahai, Wang Yu, and Liu Jianguo
Laser induced breakdown spectroscopy (LIBS) combined with the standard addition method is used to detect the Cr concentration in soil. With the Cr 425.435 nm line as the characteristic line and Fe as the internal standard element, the Cr calibration curve is established. Based on the fact that when the Cr mass fractionLaser induced breakdown spectroscopy (LIBS) combined with the standard addition method is used to detect the Cr concentration in soil. With the Cr 425.435 nm line as the characteristic line and Fe as the internal standard element, the Cr calibration curve is established. Based on the fact that when the Cr mass fraction is below 250×10-6, the spectral intensity of characteristic line has a linear relationship with its mass fraction, the limit of detection is 9.69×10-6 and the detection range of the standard addition method is obtained. The standard addition methods with one and five extrapolated points are studied. For five-point standard addition method, the relative error of test results of Cr in soil is less than 7%. For one-point standard addition method, the relative error is less than 10%. Detect one soil sample by one-point standard addition method for five times, the relative standard deviation (RSD) of the test results is 4.66%, which is relatively stable. Experimental results show that LIBS combined with standard addition method can perform well in quantitative detection of Cr in soil..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 715002 (2014)
Study on Removing Method of Continuous Background Spectrum in LIBS of Multi-Element Heavy Metals in Water
Hu Li, Zhao Nanjing, Liu Wenqing, Fang Li, Zhang Dahai, Wang Yin, Meng Deshuo, Yu Yang, Ma Mingjun, Xiao Xue, Wang Yu, and Liu Jianguo
Continuous background spectrum is an important influencing factor of laser induced breakdown spectrometry (LIBS) quantitative measurement of multi-element heavy metals in water. According to the characters that the background spectrum changes slowly and full width at half maximum of characteristic spectral lines is narContinuous background spectrum is an important influencing factor of laser induced breakdown spectrometry (LIBS) quantitative measurement of multi-element heavy metals in water. According to the characters that the background spectrum changes slowly and full width at half maximum of characteristic spectral lines is narrow, the sliding window integral slope algorithm for removing continuous backgrounds is studied. Seting appropriate window width and slope threshold to identify the background spectrum and characteristic peaks, the assignment is carried out on window background, the background spectrum is extracted completely. The experimental results show that the signal-to-background ratios of plumbum and copper are 5.7 times and 1.95 times respectively to that before removing the background, the relative standard deviations are reduced by 2% and 2.5% respectively. The sliding window integral slope algorithm is a stable and effective method for removing backgrounds in LIBS, and also provids an reference for removing backgrounds in other optical spectrum analysis technology..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 715003 (2014)
Two-Photon Polarization Spectroscopy of Rubidium 4D5/2 State and Its Application for Frequency Stabilization of 1.5 μm Laser
Liu Huifeng, Wang Jie, Yang Guang, Yang Baodong, He Jun, and Wang Junmin
The two-photon polarization spectroscopy (TPPS) of 87Rb atoms is reported based on the 5S1/2-5P3/2-4D5/2 ladder-type atomic system. Compared with other transitions, the cycling transition shows much better signal-to-noise ratio. TPPS cycling transition signal versus intensity of the pumping laser is investigatived. TheThe two-photon polarization spectroscopy (TPPS) of 87Rb atoms is reported based on the 5S1/2-5P3/2-4D5/2 ladder-type atomic system. Compared with other transitions, the cycling transition shows much better signal-to-noise ratio. TPPS cycling transition signal versus intensity of the pumping laser is investigatived. The frequency of a 1529 nm laser diode is stabilized to the 5P3/2(F′=3)-4D5/2(F″=4) hyperfine transition of 87Rb atoms by using TPPS. The minimum value of Allan variance σy(τ) is 1.3×10-11 at the interrogation time τ of 100 s. Compared with the free-running case, this new method remarkably improves the long-term frequency stability of the 1529 nm laser..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 7, 715004 (2014)
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