Journals >Laser & Optoelectronics Progress
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2017
Volume: 54 Issue 6
42 Article(s)
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Diffraction and Gratings
Optimal Design of Depth-Scaling Error with Oblique Incidence
Yang Liangliang, Liu Chenglin, Zhang Zhihai, and Tang Jian
Based on the expression between diffraction efficiency and incident angle and the expression between diffraction efficiency and micro-structure height error under normal incidence, the mathematical relationship between micro-structure height error and diffraction efficiency or polychromatic integral diffraction efficieBased on the expression between diffraction efficiency and incident angle and the expression between diffraction efficiency and micro-structure height error under normal incidence, the mathematical relationship between micro-structure height error and diffraction efficiency or polychromatic integral diffraction efficiency (PIDE) for diffractive optical elements (DOEs) under oblique incidence is established. When the absolute value of the relative micro-structure height errors is equal, the corresponding diffraction efficiency and PIDE with negative micro-structure height errors are higher than those with positive micro-structure height errors. The analysis method and conclusion provide a theoretical reference for the determination of the machining tolerance of micro-structure height error for DOEs..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 60501 (2017)
Characteristic Analysis of High-Order Tunable Bragg Waveguide Grating Based on Lithium Niobate
Wang Zhao, Zhang Ailing, Tian Hongmiao, and Li Qingqing
A high-order tunable Bragg waveguide grating can be prepared on lithium niobate by using the methods of photolithography and titanium diffusion. Its related characteristics are analyzed. The effects of duty cycle, grating order, waveguide width difference and applied voltage on the reflective spectral properties of higA high-order tunable Bragg waveguide grating can be prepared on lithium niobate by using the methods of photolithography and titanium diffusion. Its related characteristics are analyzed. The effects of duty cycle, grating order, waveguide width difference and applied voltage on the reflective spectral properties of higher-order Bragg waveguide gratings are analyzed. The results show that the refractive index modulation depth, the maximum reflectivity and the zero bandwidth of gratings change periodically with the duty cycle, and the central wavelength shifts to the longer wavelength with the increase of duty cycle. When the best duty cycle is chosen for each order grating, the refractive index modulation depth is the largest, and the maximum reflectivity increases and the zero bandwidth decreases with the increase of grating length. With the increase of waveguide width difference, both of the maximum reflectivity and the zero bandwidth increase, and the central wavelength shifts to the longer wavelength. Moreover, with the increase of applied voltage, the reflective spectral shapes almost remain the same and the central wavelength shifts to the longer wavelength and presents a linear growth trend..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 60502 (2017)
Fiber Optics and Optical Communications
Frequency Assignment Algorithm for Elastic Optical Network with Multi-Cores Considering Crosstalk
Jiang Xiangkui, Zhao Feng, Fan Yongqing, and Zhang Yinliang
This investigation focuses on the routing, core allocation and spectrum assignment problems in elastic optical network with multi-cores. To minimize the maximum index of used frequency slots, a global constraint optimization model with crosstalk rate of adjacent cores meeting certain threshold requirement is proposed. This investigation focuses on the routing, core allocation and spectrum assignment problems in elastic optical network with multi-cores. To minimize the maximum index of used frequency slots, a global constraint optimization model with crosstalk rate of adjacent cores meeting certain threshold requirement is proposed. In order to solve the model efficiently, a global optimization genetic algorithm is proposed. The groomed connection requests are sorted, and the designed genetic algorithm is used to obtain the optimal schemes of routing and core allocation for all the connection requests. To evaluate the efficiency of the proposed algorithm, different simulations are conducted. The simulation results show that the proposed algorithm can reduce the maximum index of used frequency slot and improve spectrum efficiency..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 60601 (2017)
Single-Mode Fiber Coupling Based on Raster Spiral Scanning and SPGD Algorithm
Wu Zikai, Chen Mo, Liu Chao, and Xian Hao
For free-space optical communication systems, spatial light must be efficiently coupled into the single-mode fiber first. However, the initial alignment error and the random lateral deviation existed between focused spot and single-mode fiber lead to a dramatic coupling loss. A theoretical model of coupling the spatialFor free-space optical communication systems, spatial light must be efficiently coupled into the single-mode fiber first. However, the initial alignment error and the random lateral deviation existed between focused spot and single-mode fiber lead to a dramatic coupling loss. A theoretical model of coupling the spatial light into single-mode fiber is expounded, and the effects of the lateral deviation and the random jitter on coupling efficiency are analyzed. On this basis, in order to improve the fiber coupling efficiency, a coupling scheme based on raster spiral scanning algorithm and stochastic parallel gradient descent (SPGD) algorithm is proposed. Simulations on the process of error correction and the improvement of coupling efficiency after error correction are carried out. The results show that, by setting the optimal scanning step, the initial alignment error can be efficiently corrected by raster spiral scanning algorithm, the success probability of initial alignment error correction can be higher than 99%. The residual initial alignment error focuses in 0.5-0.6 μm, and the coupling efficiency has been improved perliminarily. By adopting the SPGD algorithm, the random lateral deviation between focused spot and single-mode fiber can be corrected, and the coupling efficiency also rises to 0.81, which approaches the theoretical limit without turbulence. After the correction, the coupling efficiency is significantly improved..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 60602 (2017)
Novel Photonic Crystal Fiber with High Birefringence and Low Loss
Gu Qianzhi, and Li Qianghua
A novel photonic crystal fiber with high birefringence and low loss is designed. Based on full vector finite element method, the effective refractive index, birefringence, dispersion, loss and field properties of the photonic crystal fiber are analyzed when we change the elliptical structure parameters. Results show thA novel photonic crystal fiber with high birefringence and low loss is designed. Based on full vector finite element method, the effective refractive index, birefringence, dispersion, loss and field properties of the photonic crystal fiber are analyzed when we change the elliptical structure parameters. Results show that dispersion point control of the novel fiber in the range from 1300 nm to 1500 nm can be realized when we change ellipticity. When the ellipticity is 0.6, the fiber has a high birefringence of 2.55×10-2 and low loss of 2.4×10-2 dB/km. A zero dispersion point appears in the range from 1300 nm to 1500 nm. Performance of the novel fiber is better than that of the traditional fiber, and it has a certain application prospect in the field of optical communications and optical fiber sensing..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 60603 (2017)
Holography
Effect of the Size of High-Pass Filter on the Off-Axis Particle Holographic Image
Zhang Lianyong, Xu Qing, Cao Na, Cao Liang, Li Binkang, Liu Yunya, and Lei Lan
The holography of particle field by off-axis filter is an effective method for reducing the background noises and improving the reconstructed image quality. The filter size and the reconstructed particle image are closely related, a suitable filter size is important for the particle recognition and measurement. The relThe holography of particle field by off-axis filter is an effective method for reducing the background noises and improving the reconstructed image quality. The filter size and the reconstructed particle image are closely related, a suitable filter size is important for the particle recognition and measurement. The relationship between the high-pass filter size, front focal length of 4F system, particle size and the intensity distribution of holographic reconstructed images of circle particle by off-axis filter are analyzed respectively, and the influences of different high-pass filter sizes on the same size particle images are simulated numerically. In addition,the off-axis filtering holography experiment is carried out. The results show that, the particle image contrasts are increased effectively by the high-pass filter. The uniformity of the reconstructed image intensity distribution becomes better, and the boundary gradient increases with the smaller the filter size or the larger the front focal length of 4F system, while with the increasing of particle size, some black and white circles appear gradually in the reconstructed particle image interior, and the particle boundary becomes increasingly clear..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 60901 (2017)
Image Processing
Adaptive Solar Speckle Image Reconstruction Based on Multi-Core CPU
Tang Ruolin, Tian Yu, Zhong Libo, and Rao Changhui
In solar ground-based high resolution imaging, the speckle image reconstruction is used to yield diffraction-limited resolution for partially corrected images with the solar adaptive optics system. The C language program which adopts speckle interferometry to reconstruct the Fourier amplitudes and speckle masking to reIn solar ground-based high resolution imaging, the speckle image reconstruction is used to yield diffraction-limited resolution for partially corrected images with the solar adaptive optics system. The C language program which adopts speckle interferometry to reconstruct the Fourier amplitudes and speckle masking to reconstruct the Fourier phase is generated from Matlab procedure. The speckle image reconstruction is based on the multi-core central processing unit architecture. The C program is parallelized by OpenMP, and the program is partitioned by sub-image. In addition, the redundancy calculating is removed. This program is compiled by Intel ICC and run on a 12 cores server with Centos 7.0. As a result, a 1280 pixel×1280 pixel object image can be reconstructed from 100 speckle images within 31 s. Compared with the program run on single core, the speedup is around 10.66. The scalability is better than the program that parallelized by message-passing interface is single server..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 61001 (2017)
Estimation of Lighting Parameters for Uniform Texture Image
Sun Yujuan, Dong Junyu, and Wang Zengfeng
Estimating lighting direction from a single input image requires too many unknown parameters, whereas although the accurate estimated lighting parameters from multiple input images can be obtained, the complexity of the input data is increased. The method for lighting parameters estimation of the uniform texture imagesEstimating lighting direction from a single input image requires too many unknown parameters, whereas although the accurate estimated lighting parameters from multiple input images can be obtained, the complexity of the input data is increased. The method for lighting parameters estimation of the uniform texture images is proposed. The proposed algorithm only utilizes one input image for estimating the lighting directions. By detecting the largest direction of the brightness changes of the input image, the azimuth angle of the light source can be estimated. The slant angle is estimated by detecting the similarity between the input image and the random texture with virtual lighting conditions. 24 kinds of texture images (142 images) in Photex database are studied experimentally. Experimental results show that the proposed approach is effective and robust in estimating the lighting parameters for the uniform texture images..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 61002 (2017)
Imaging Systems
Low Contrast Target Detection Based on Visible Light Polarization Imaging System
Hu Dongmei, Liu Quan, and Niu Guocheng
In order to detect the low contrast targets in the complicated background, the time division full polarization imaging system based on dual liquid crystal variable retarders (LCVR) is developed, and an optimum combination scheme based on the minimum 2-norm is proposed in the control of LCVR phase retardation. The systeIn order to detect the low contrast targets in the complicated background, the time division full polarization imaging system based on dual liquid crystal variable retarders (LCVR) is developed, and an optimum combination scheme based on the minimum 2-norm is proposed in the control of LCVR phase retardation. The system instrument matrix is calibrated with the optimum phase retardation combination, and the field imaging experiment is carried out when the green coating targets are hidden in the shade. The experimental result shows that the contrast between the target and its background is almost zero in the ordinary intensity image and 0.2525 in the S0 image obtained by inversion. The achieved result further proves that the system can effectively realize low-contrast target detection in complex background..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 61101 (2017)
Instrumentation, Measurement and Metrology
Design of Real-Time Measuring System for Autostereoscopic 3D Displays
Ma Hongqin, Wang Xiaolu, Fan Hang, Wang Jiahui, Zhou Jianying, and Zhou Yangui
To improve the fit efficiency of optical membranes and displays and overall alignment precision in autostereoscopic 3D displays, this article proposes an overall, high efficiency and real-time measurement scheme for optical properties of 3D displays. The corresponding measurement system is developed. The real-time measTo improve the fit efficiency of optical membranes and displays and overall alignment precision in autostereoscopic 3D displays, this article proposes an overall, high efficiency and real-time measurement scheme for optical properties of 3D displays. The corresponding measurement system is developed. The real-time measurement of luminance uniformity and crosstalk ratio uniformity for 3D display screen is realized. Photodiode array of the measurement system is designed and developed. Circuit control module with high sensitivity and high precision is fabricated. And software of upper computer is designed to display data in real time. The spectral response of the photodiodes is close to that of human eyes. The calibrated and directionally corrected photodiodes can be used to measure light intensity distributions of visual area from different parts on screen in real time. The crosstalk ratio data from different parts on screen can be calculated quantitatively with obtained data. Experimental results show that the system is capable of effectively measuring spatial light intensity distribution within 23.7 cm width, which covers a pair of eyes′visual area. The measurement precision of the system is 1.58 mlx. Results prove that the data can quantitatively reflect luminance and crosstalk ratio perceived by human eyes. This method can be used to measure light intensity distribution of visual area for 3D displayer in real time, and calculate crosstalk ratio distribution. Which is beneficial to enhance the fabrication efficiency of autostereoscopic 3D display devices..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 61201 (2017)
Adaptive Planning Method of Spatial Scanning Range for White Light Interferometric Profiler
Ma Long, Lü Yi, Pei Xin, Jiao Zhichao, Zhang Hongyan, and Hu Yanmin
In order to improve the measurement efficiency of white light interferometric profilers, one new adaptive planning method of spatial scanning range is proposed. The corresponding measurement system is built and the energy gradient function is chosen to locate the optimal interference position. The interference fringes In order to improve the measurement efficiency of white light interferometric profilers, one new adaptive planning method of spatial scanning range is proposed. The corresponding measurement system is built and the energy gradient function is chosen to locate the optimal interference position. The interference fringes of charge coupled device (CCD) images at the optimal interference positions are extracted with the ViBe algorithm, and then the extraction results are processed by the binaryzation. The experimental results show that the proposed method can accurately identify the positions of the function upper and lower limits..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 61202 (2017)
Glucose Concentration Measurement Based on Liquid Optical Rotation Effect
Huang Zhen, Liang En′en, Lin Xuegui, Huang Mingjun, Zeng Zhiming, and Zhong Huichan
The glucose concentration is one of the main characteristics of solution. Based on the optical rotation effect of glucose solution, motor modulation analyzer, and dual light path simultaneous detection, glucose concentration is obtained from the phase difference of the two modulation signals. Experimental results show The glucose concentration is one of the main characteristics of solution. Based on the optical rotation effect of glucose solution, motor modulation analyzer, and dual light path simultaneous detection, glucose concentration is obtained from the phase difference of the two modulation signals. Experimental results show that the maximum relative error is about 6.48% with glucose concentration from 0% to 50% (mass fraction). The proposed method solves the problem that rotation angle measurement is limited by mechanical rotation equipment. The measurement equipment has the advantages of simple structure, rapid measurement and strong anti-interference..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 61203 (2017)
Self-Interference for Spatial Light Modulator Phase Modulation Characteristics by Liquid Crystal Grating
Zhao Zixin, Xiao Zhaoxian, Zhang Hangying, and Zhao Hong
A self-interference method for measuring phase modulation characteristics of parallel liquid crystal spatial light modulator (SLM) is proposed. The method is experimentally simple and robust. The gray image loaded onto the SLM is composed of three parts, one is a binary diffraction grating grayscale map, the other two A self-interference method for measuring phase modulation characteristics of parallel liquid crystal spatial light modulator (SLM) is proposed. The method is experimentally simple and robust. The gray image loaded onto the SLM is composed of three parts, one is a binary diffraction grating grayscale map, the other two maps are codified by a uniformly distributed gray level area, where the gray value below the part is constantly 0, the upper part gray value is gradually increased from 0. With the gray value of the upper part changing, the reflected beam by modulation interferes with the +1 order grating diffraction wave to generate a whole dislocation fringes, the amount of SLM phase modulation can be calculated by measuring the cycle and the relative displacement between the upper and lower fringes on the same interference pattern. This proposed method eliminates the influence of the fringe jitter caused by ambient vibration or air turbulence on the measurement and improves the measurement accuracy. Compared with other methods, the new method which obtains the phase modulation characteristics of SLM does not require complex optical devices, and has excellent mechanical stability, fast response and easy to implement..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 61204 (2017)
Precision Design and Analysis of Large Curvature Radius Measurement System
Wei Fenglong, Tian Wei, and Peng Shijun
According to the demand of high precision optical system and the present research achievements, a large curvature radius measurement system is developed based on the interferometric measurement. Error factors affecting the measurement precision of the developed system are analyzed, and a mathematical model of error disAccording to the demand of high precision optical system and the present research achievements, a large curvature radius measurement system is developed based on the interferometric measurement. Error factors affecting the measurement precision of the developed system are analyzed, and a mathematical model of error distribution and an error distribution tree of the measurement system are established based on the error theory and the system composition. Combined the actual usage requirements, the target uncertainty of the measurement precision of the system is distributed and then combined. Results show that the standard uncertainty is 2.49 μm, and it less than 2.5 μm which is the target uncertainty required by the system. The distribution result is used as the input index for the design of subsystem structures. Measures that can improve the measurement precision of curvature radius are proposed and summarized. According to the error distribution result, a system for measuring large curvature radius which can satisfy the using requirements is designed..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 61205 (2017)
Lasers and Laser Optics
Thermal Effect Simulation Analysis on Excimer Laser Annealing of Zinc Oxide Thin Films
Shao Jingzhen, Wang Xi, Hu Hongtao, and Fang Xiaodong
Based on the heat conduction equation, a theoretical model related to the excimer laser irradiation of ZnO thin films is built. The thermal effect in the KrF excimer laser irradiation of ZnO thin films is simulated and analyzed. The distributions of temperature field and thermal flux of the films are calculated. The vaBased on the heat conduction equation, a theoretical model related to the excimer laser irradiation of ZnO thin films is built. The thermal effect in the KrF excimer laser irradiation of ZnO thin films is simulated and analyzed. The distributions of temperature field and thermal flux of the films are calculated. The variation relationship between temperature and time during the laser action process is discussed. The influence of the laser energy density on the temperature field of the films is analyzed. The simulation results show that the excimer laser annealing process of ZnO thin films has the heat quench characteristic, the surface temperature of ZnO thin films increases linearly with the laser energy density, and the thermal melting threshold of film surfaces is 261 mJ/cm2..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 61401 (2017)
Corrosion Resistance Property of 316L Stainless Steel Welding Joints Treated by Laser Shock Peening
Li Yuqin, Meng Changjun, Wang Xuede, Luo Sihai, and Xu Weisheng
The corrosion resistance property of 316L stainless steel welding joints is improved with the laser shock peening method. The microstructure and the residual stress distribution on the welding joint surface are analyzed. The results show that the residual tensile stress on the welding joint surface treated by laser shoThe corrosion resistance property of 316L stainless steel welding joints is improved with the laser shock peening method. The microstructure and the residual stress distribution on the welding joint surface are analyzed. The results show that the residual tensile stress on the welding joint surface treated by laser shock peening is significantly reduced. The electrode potential of the welding joints increases and the diffusion of corrosive media is hindered. Moreover, as a result of laser shock peening, the matrix grain is refined and a large number of slip bands and deformation twins form, which makes the extension of stress corrosion cracks be delayed and improves the corrosion resistance property of 316L stainless steel welding joints..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 61402 (2017)
Output Characteristics of Few Hundreds kHz Picosecond Regenerative Amplifiers
Zhao Peng, Chen Meng, Yu Lingjie, and Long Mingliang
Considering that the energy extraction period becomes much smaller than the energy upper state lifetime of the laser gain media, the output laser of high repetition rate regenerative amplifiers contains two-different-energy pulses, which is generally described as the period doubling bifurcation phenomenon. In order to Considering that the energy extraction period becomes much smaller than the energy upper state lifetime of the laser gain media, the output laser of high repetition rate regenerative amplifiers contains two-different-energy pulses, which is generally described as the period doubling bifurcation phenomenon. In order to solve this problem, we study the relation between the output laser pulse stabilization of high repetition rate regenerative amplifiers and repetition rate theoretically, and find that the period doubling bifurcation phenomenon can be avoided by increasing the repetition rate of regenerative amplifiers. The experimental results show the period doubling bifurcation phenomenon is avoided when the repetition rate is more than 250 kHz. Furthermore, the regenerative amplification of 1 nJ pulse enenrgy is produced by all-solid-state Nd∶YVO4 crystal semiconductor saturable absorber mirror mode-locked picosecond laser with the repetition rate of 94 MHz. And when the absorbed pump laser is 70 W, we get the frequency tunable (250-500 kHz) picosecond laser. The maximum output average power is 18 W, and the single pulse energy is 36 μJ..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 61403 (2017)
Study on Aluminum Alloy Laser Welding with Pre-Melted Liquid Filler by Arc
Peng Jin, Li Liqun, Zhang Ruizhu, and Yan Dakao
The method of laser welding with pre-melted liquid filler by arc is proposed, and the influence of incident energy on the melting state of the filler wire and the weld appearance is studied. The process adaptability of the welding process is further analyzed. The results show that, when the welding current is relativelThe method of laser welding with pre-melted liquid filler by arc is proposed, and the influence of incident energy on the melting state of the filler wire and the weld appearance is studied. The process adaptability of the welding process is further analyzed. The results show that, when the welding current is relatively low, the filler wire can be stably melted and filled into the molten pool, and the increase of the welding current is beneficial to increasing the melting length of the front-end filler wire. The increase of the laser power has no effect on the melting amount of the filler wire. The method of laser welding with pre-melted liquid filler by arc can reduce the porosity of weld and significantly improve the adaptability to assembly clearance..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 61404 (2017)
Effects of Graphite on Structure and Property of Laser Cladded Fe-Based Amorphous Composite Coatings
Zhu Hongmei, Lin Ziqin, Ye Wei, and Shen Longzhang
Fe-based amorphous composite coatings added with graphite are fabricated on 304L stainless steel surface by laser cladding with the addition of graphite. The effects of the added graphite on the microstructure and property of these coatings are studied. The results show that the coatings without graphite addition are cFe-based amorphous composite coatings added with graphite are fabricated on 304L stainless steel surface by laser cladding with the addition of graphite. The effects of the added graphite on the microstructure and property of these coatings are studied. The results show that the coatings without graphite addition are composed of α-Fe, boron-containing phases (Fe23B6, CrB) and γ-(Ni, Cr, Fe) phases, and the volume fraction of the amorphous phase is 35.9%. However, in those with graphite addition, the new carbon-containing phases (Fe3C and Cr7C3) are formed, and the volume fraction of the amorphous phase is increased to 41.6%. The bond zones of coatings without graphite addition are evenly distributed by irregular granular phases and the cladding layers have a rice-like shape. The bond zones of coatings with graphite addition exhibit cellular dendrites, and the cladding layers have a needle-like crystal structure where dark gray spherical particles are embedded. The average microhardness of the cladding layers before or after graphite addition is 792.2 HV and 968.7 HV, respectively..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 61405 (2017)
Femtosecond Laser Fabrication and Sensing Performance of Birefringence Fiber Bragg Gratings
Meng Aihua, Cui Dingyuan, Zhang Xuanyu, Chen Chao, and Yu Yongsen
A panda-type birefringence fiber Bragg grating (PF-FBG) is fabricated by femtosecond laser direct writing technique. To get the grating, the femtosecond laser is focused into optical fiber core. During the process of exposure, the optical fiber is moved at a constant speed. Finally, a periodic refractive index modulatiA panda-type birefringence fiber Bragg grating (PF-FBG) is fabricated by femtosecond laser direct writing technique. To get the grating, the femtosecond laser is focused into optical fiber core. During the process of exposure, the optical fiber is moved at a constant speed. Finally, a periodic refractive index modulation area is obtained. Because of the birefringence characteristics of PF-FBG, the reflection spectrum with two peaks is generated at 1550 nm wavelength. As a result, it can be used in multi-parameter sensing monitoring. The sensing properties of temperature and axial stress of the PF-FBG are studied. Besides, the femtosecond laser induced grating shows a good stability in high temperature, and shows potential applications in chemical and physical sensing under harsh circumstances..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 61406 (2017)
Compact and Efficient GHz Nd∶GdVO4/V∶YAG Q-Switched Mode-Locked Laser at 1.34 μm
Cao Qiuyuan, Peng Jiying, Li Zuohan, and Han Ming
A compact and efficient GHz Nd∶GdVO4/V∶YAG Q-switched mode-locked laser at 1.34 μm is proposed. A laser diode is used for end-pumping, and a compact and linear cavity is combined with an output coupler with transmittance of 10%. Correlation experimental conditions of laser crystal are optimized, and correlation propertA compact and efficient GHz Nd∶GdVO4/V∶YAG Q-switched mode-locked laser at 1.34 μm is proposed. A laser diode is used for end-pumping, and a compact and linear cavity is combined with an output coupler with transmittance of 10%. Correlation experimental conditions of laser crystal are optimized, and correlation properties of laser crystal are theoretical analyzed. A Nd∶GdVO4 crystal is used in experiment. The Nd3+ doping mass concentration is 0.2%, and the initial transmission of V∶YAG crystal is 83%. The repetition rate of mode-locked pulse is up to 2 GHz, and nearly 100% mode-locked modulation depth can be obtained. The maximum output power of the Q-switched mode-locked laser is 715 mW. Based on the fluctuation mechanism theory, a mode-locked pulse figure of single Q-switched envelope is simulated, and the simulation results agree well with the experimental results..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 61407 (2017)
Orthogonal Experiments and Variance Analysis in Nd∶YAG Pulsed Laser Trepanning Drilling
Ren Naifei, Zhang Li, Wang Houxiao, Xia Kaibo, and Shi Chunhui
The Taguchi′s orthogonal array method with four factors and four levels is used to carry out the experimental investigation of the Nd∶YAG pulsed laser trepanning drilling of the superalloys with the thickness of 3 mm. The influences of pulse energy, defocusing amount, number of trepanning and trepanning speed on hole tThe Taguchi′s orthogonal array method with four factors and four levels is used to carry out the experimental investigation of the Nd∶YAG pulsed laser trepanning drilling of the superalloys with the thickness of 3 mm. The influences of pulse energy, defocusing amount, number of trepanning and trepanning speed on hole taper and hole circularity are analyzed. The laser processing parameters are also optimized and the minimum microhole taper and the relatively better microhole circularity are obtained. The results show that the influences of pulse energy, defocusing amount, number of trepanning, and trepanning speed on microhole circularity are not significant during the laser trepanning drilling process, while the influence of defocusing amount on microhole taper is the most. Moreover, the minimum microhole taper is obtained when using the optimal laser processing parameters as the number of trepanning of 6, trepanning speed of 6 mm/min, pulse energy of 1.5 J, and defocusing amount of -0.5 mm. In addition, the hole circularity at exit is better than that at entry..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 61408 (2017)
Design of Adjustable Beam Expanding Focusing Lens for Laser Vibration
Wu Junfeng, Shu Fengfeng, and Wu Yihui
A beam expanding focusing lens of single scanning laser vibrometer is analyzed and designed by ZEMAX. Firstly, the Gauss He-Ne laser source is simulated, and then the initial structure of the system is calculated. The relationship between the moving distance of the front lens and the laser focusing distance is analyzedA beam expanding focusing lens of single scanning laser vibrometer is analyzed and designed by ZEMAX. Firstly, the Gauss He-Ne laser source is simulated, and then the initial structure of the system is calculated. The relationship between the moving distance of the front lens and the laser focusing distance is analyzed, and the spot sizes at different focusing distances are obtained. Finally, the mechanical structure of the adjustable focusing system is designed. The adjustment of the structure is smooth, and the front lens can not rotate. Thereby the errors caused by rotating lens are reduced..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 61409 (2017)
Broadening the Bandwidth of Chaotic Carrier Transmitter in Semiconductor Lasers with Chaotic Optical Injection
Sun Weiyang, Zhang Shenghai, Wu Tianan, and Zhang Xiaoxu
A scheme of broadening the bandwidth of chaotic carrier transmitter in semiconductor lasers, namely, semiconductor lasers with chaotic optical injection is analyzed. The influence of the parameters, such as the detuning frequency, injection strength, bias current and slave laser feedback intensity, on the chaotic carriA scheme of broadening the bandwidth of chaotic carrier transmitter in semiconductor lasers, namely, semiconductor lasers with chaotic optical injection is analyzed. The influence of the parameters, such as the detuning frequency, injection strength, bias current and slave laser feedback intensity, on the chaotic carrier transmitter bandwidth and master laser feedback intensity on the time delay signature are analyzed respectively by numerical simulation. The parameter set of which can broad the bandwidth to 25.8 GHz is confirmed, and it is five times than the original bandwidth of 5.1 GHz..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 61410 (2017)
Materials
Influence of Ag Diffusion on Structure and Optical Property of Ag/MgF2 Film Interface
Wang Liping, Yang Jianxin, and Han Peide
The interface energies of different Ag(111)/MgF2(001) film interface structures are calculated based on the first-principle of density functional theory, and the stability of film interfaces is analyzed. The Ag(111)/MgF2(001) interface model with Ag diffusion is built to study the Ag diffusion behavior and mechanism atThe interface energies of different Ag(111)/MgF2(001) film interface structures are calculated based on the first-principle of density functional theory, and the stability of film interfaces is analyzed. The Ag(111)/MgF2(001) interface model with Ag diffusion is built to study the Ag diffusion behavior and mechanism at the interface. The influence of Ag diffusion on optical property of films is analyzed. The results show that the interface structure of the built smooth-interface-model is stable. The Ag diffusion at the Ag(111)/MgF2(001) interface mainly occurs at the surface/subsurface layers. The interaction between the diffused Ag and nearby F and Mg is weakly covalent. The Ag diffusion makes film optical absorption increase and the refractive index decrease, especially in the visible light wavelength region, the reduction of the refractive index is more obvious..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 61601 (2017)
Medical Optics and Biotechnology
Capsule Endoscopy Localization Method of High Dynamic Accuracy in Magnetic Disturbance
Niu Desen, Chen Xiaodong, Du Chengyang, Wang Yi, and Yu Daoyin
Capsule endoscopy is a new examination method of gastrointestinal tract. The tracking and localization technique of capsule endoscopy still have the problems of poor dynamic accuracy and tracking failure under magnetic disturbance. This paper proposes a magnetic localization method based on particle filter (PF). ComparCapsule endoscopy is a new examination method of gastrointestinal tract. The tracking and localization technique of capsule endoscopy still have the problems of poor dynamic accuracy and tracking failure under magnetic disturbance. This paper proposes a magnetic localization method based on particle filter (PF). Compared with traditional localization method, the proposed PF method can effectively avoid the poor accuracy in the dynamic tracking, and overcome high sensitivity to magnetic disturbance generated by the ferromagnetic materials or surrounding electrical currents. The estimation of the target movement and the estimation of the magnetic disturbance are added in the designed PF algorithm. The estimation of the target movement is applied to compensate measured value of magnetic field when the measurement under time sequence sampling isn′t real time. The estimation of the magnetic disturbance can compensate the magnetic disturbance. The experimental results show that, under limited magnetic disturbance (＜1.5 μT), traditional localization method cannot work. For the dynamic localization, the averaged error of the proposed method is less than 6 mm, which meets the requirements of the clinical application..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 61701 (2017)
Optical Design and Fabrication
Micro-Optics Label System Based on Six-Reflection Fold Annular Aperture Lens
Chen Wei, Liang Zhongcheng, Ge Lan, and Kong Meimei
A special micro-optics label system is introduced. A large aperture and long focal length lens structure, which is used as the system receiving terminal, is demonstrated to be able to improve the imaging performance significantly by theoretical analysis. A six-reflection fold annular aperture ultra-thin lens with largeA special micro-optics label system is introduced. A large aperture and long focal length lens structure, which is used as the system receiving terminal, is demonstrated to be able to improve the imaging performance significantly by theoretical analysis. A six-reflection fold annular aperture ultra-thin lens with large aperture and long focal length is designed with the aid of optical engineering software Zemax. The front surface is a plane mirror and the rear surface consists of four concentric annular aspheric reflectors. The outer diameter of the lens is 28 mm, the effective focal length is 38 mm, and the thickness of the lens is 5 mm. With the clear aperture consistency of a four-reflection fold annular aperture lens, the structure of the equipment is improved to increase the number of reflections, effectively reduce the thickness of the lens, and enlarge the focal length of lens. In this work, an optimized design and analysis to the micro-optics label system are reported. It is based on the annular aperture ultra-thin lens as receiving terminal. And the comparison of simulation imaging is given. The results show that using six-reflection fold annular aperture lens as receiving terminal can increase the receiving distance and reduce the distortion of simulated images. Finally, a received image with non-uniform brightness is effectively corrected by using homomorphic filtering method..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 62201 (2017)
Optical Devices
Design and Experiment of Special-Shaped LED Lamp with Honeycomb Radiator
Tang Fan, Wang Dan, and Guo Zhenning
To improve the cooling capacity of light emitting diode (LED) lamps, a new type of LED lamp radiating structure is designed based on the principle of the chimney effect. A three-dimensional model is built by SolidWorks, and its plug called Flow Simulation is used to simulate the model build. The highest temperature of To improve the cooling capacity of light emitting diode (LED) lamps, a new type of LED lamp radiating structure is designed based on the principle of the chimney effect. A three-dimensional model is built by SolidWorks, and its plug called Flow Simulation is used to simulate the model build. The highest temperature of LED chip is 81.34 ℃ when the power is 10 W. When the power is increased to 15 W, the highest temperature is 105.54 ℃, and it is higher than the security temperature (80 ℃) of LED chip. An improved scheme of adding the honeycomb radiator in the middle of the substrate is proposed. Which reduces the highest temperature of the LED chip by 30.54 ℃, and the optimization experiment is carried out. The results show that when the type of honeycomb is regular hexagon, the length of honeycomb is 6.0 mm and the thickness of the honeycomb is 1.0 mm, special-shaped LED lamp has the best heat dissipation effect. The highest temperature of LED chip is 74.47 ℃ and radiator mass is 47.19 g. When the power is 8, 12, 15, 18 W, the highest temperatures of the LED lamp meet the safety requirements. The accuracy of the study is confirmed by the experiment of 8 W special-shaped LED lamp samples..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 62301 (2017)
Research on Lighting Sources of High Photometric-Colorimetric Properties LEDs
Lai Chuandu, Zhuang Qiren, Hu Yibin, and Liu Shiwei
In order to solve the contradiction that light emitting diode (LED) lighting sources with high color rendering index may still exist rich-blue light hazards, the spectral visual similarity model of test light source spectrum with the reference light source spectrum is established based on spectral luminous efficiency, In order to solve the contradiction that light emitting diode (LED) lighting sources with high color rendering index may still exist rich-blue light hazards, the spectral visual similarity model of test light source spectrum with the reference light source spectrum is established based on spectral luminous efficiency, color-resolution function and spectral response function. A method is proposed to design high photometric-colorimetric property LED synthetic light source according to spectral visual similarity parameter (RV). Using the D50, the standard light source recommended by Commission Internationale de L′Eclairage (CIE), as reference illuminant, with the LEDs of cold white, warm white, red, green, cyan and blue are combined. The lamp numbers of all kinds of LED combination are calculated by traverse optimization method. According to the requirement of RV＞96, it turns out that the corresponding color temperature range of LED synthetic light source is between 4000-7000 K, and the general color rendering index Ra＞95 are accordant with the requirements of high photometric-colorimetric property and health in illumination light sources. Which proves the rationality of the proposed method. The results also show that, by choosing CIE standard light source with different color temperatures as the reference illuminant, we can design high color rendering of white light with different color temperatures..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 62302 (2017)
Physical Optics
Mechanism Analysis of Faraday Effect Based on Magneto-Optic Coupling
Cai Wei, Xing Junhui, Yang Zhiyong, and Yao Ruiqiao
In order to elucidate the mutual influence mechanism among the factors in the magneto-optic modulation process based on Faraday effect, a multi-field coupling theory is introduced. A transmission model of polarized light is constructed at the condition of magneto-optic coupling when we comprehensively consider the chanIn order to elucidate the mutual influence mechanism among the factors in the magneto-optic modulation process based on Faraday effect, a multi-field coupling theory is introduced. A transmission model of polarized light is constructed at the condition of magneto-optic coupling when we comprehensively consider the change of internal parameters of the material structure under the action of the magnetic field and combine the Maxwell′s equation, and the final expression of the Faraday rotation angle is obtained. Coupled simulating and numerical solving are carried out with multi-field coupling software based on finite element method. The simulation results show that, a deflection angle of 2.245° occurs when the polarized light with a wavelength of 1064 nm passes through a 3 cm Tb3Ga5O12 (TGG) magneto-optic glass under magnetic induction intensity of 0.0373 T in a 10 A current excitation solenoid, while a deflection angle of 2.023° can be obtained by MR3-2 magneto-optic glass under the same condition. The correctness of the magneto-optic coupling mechanism model is verified by the comparison between the simulation results and the theoretical calculation results..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 62601 (2017)
Modulated Polarization Imaging Technique
Dai Hu, Li Danming, Li Juping, Guo Rui, and Jia Lujuan
Traditional polarization imaging techniques have a series of problems, such as the poor performance of real-time polarization imaging, the difficulty to realize the multi-spectral polarization imaging, and the impossibility to realize the hyper-spectral polarization imaging. In order to overcome these problems, a new tTraditional polarization imaging techniques have a series of problems, such as the poor performance of real-time polarization imaging, the difficulty to realize the multi-spectral polarization imaging, and the impossibility to realize the hyper-spectral polarization imaging. In order to overcome these problems, a new theory of polarization imaging is proposed based on the signal modulation-demodulation theory. According to the proposed theory, a hyper-spectral polarization imager based on grating dispersion is proposed. The spectrum signal after polarization modulation is obtained by the polarization imager, and the hyper-spectral image and the polarization image are obtained by means of frequency-domain filtering and inversion calculation. Hence, the polarization imager can achieve hyper-spectral total polarization imaging. The polarization imaging and the hyper-spectral imaging are well combined faultlessly. The theoretical validity of the proposed polarization imager is testified through the simulation experiment..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 62602 (2017)
Remote Sensing and Sensors
Comparison of Boundary Layer Heights Retrieved by Space-Based and Ground-Based Data
Li Hong, Yang Yi, and Dang Ruijun
This study aims to calculate the boundary layer height retrieved by ground-based micro-pulse lidar data, microwave radiometer data and lidar data (space-based) of corresponding space-borne CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) from the semi-arid climate observatory and laboratory oThis study aims to calculate the boundary layer height retrieved by ground-based micro-pulse lidar data, microwave radiometer data and lidar data (space-based) of corresponding space-borne CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) from the semi-arid climate observatory and laboratory of Lanzhou University (SACOL). Microwave radiometer data with parcel method, micro-pulse lidar backscatter data with curve fitting method and wavelet transform method (Haar wavelet transform method and Mexican Hat wavelet transform method), CALIPSO Level 1 scattering profile with maximum variance method and Mexican Hat wavelet transform method, and Level 2 aerosol layer product are used to calculate boundary layer height. When the wavelet transform method is used, the boundary layer height retrieved from CALIPSO Level 1 data is more sensitive to the initial value of wavelet amplitude than that from micro-pulse lidar data. For the retrieved boundary layer height, microwave radiometer data and micro-pulse lidar data are very close. The result shows apparent seasonal variation, and the boundary layer height reaches its maximum in summer. Which is the same as the retrieved result of CALIPSO Level 2 product. But the seasonal variation in boundary layer height retrieved by CALIPSO Level 1 data is not apparent..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 62801 (2017)
Pose Calibration of Laser Range Finder in Automated Guided Vehicle
Luo Zhifeng, Zhang Ke, Wang Zhigang, Zheng Jian, and Chen Yixin
In order to solve the problem of position calibration of two-dimensional laser range finder sensor in automated guided vehicles, a new calibration method is proposed. The attitude of sensors in the vehicle is obtained by solving the trajectory equation and using the sensor attitude information when the vehicle is contrIn order to solve the problem of position calibration of two-dimensional laser range finder sensor in automated guided vehicles, a new calibration method is proposed. The attitude of sensors in the vehicle is obtained by solving the trajectory equation and using the sensor attitude information when the vehicle is controlled to move straight. When the vehicle is controlled to spin in one spot, according to the sensor, the trajectories of the vehicle control points and their phase relationship, one can get the position of the sensor in the vehicle. The experimental results show that this calibration method is simple, accurate and reliable, and the calibration accuracy can meet the requirements of vehicle navigation..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 62802 (2017)
Monitoring of Soil Salinization in Yutian Oasis Based on Target Polarimetric Decomposition Method and PALSAR Radar Data
Zaytungul Yakup, Tashpolat Tiyip, Ilyas Nurmemet, Mamat Sawut, Abdugheni Abliz, and Abdusalam Abdujappar
Choosing Yutian Oasis as the study area, the polarimetric characteristic parameters are obtained from quad-polarized PALSAR-2 data in a variety of target polarization decomposition treatments. 11 polarized parameters with lesser noise are selected as the best classification features through visual interpretation to traChoosing Yutian Oasis as the study area, the polarimetric characteristic parameters are obtained from quad-polarized PALSAR-2 data in a variety of target polarization decomposition treatments. 11 polarized parameters with lesser noise are selected as the best classification features through visual interpretation to train the support vector machine classification. Wishart classification, support vector machine classification and several polarimetric decomposition methods are combined to extract the different levels of soil salinization information. Classification results are quantitatively analyzed and validated by Landsat-8 operational land imager image combined with visual interpretation and field investigation. The analysis results of confusion matrix show that, comparing with Wishart classification, the support vector machine classification increases the classification accuracy and Kappa coefficient from 80.48% to 88.00% and 0.73 to 0.83 respectively. It is illustrated that the individual coherent decomposition cannot fully exploit the rich information of PALSAR-2 data, and the good classification results can be achieved by using the target polarimetric decomposition parameter for features classification process. Using fully polarimetric PALSAR-2 data, the method combining target polarimetric decomposition with support vector machine classification has advantage to extracting salinization information..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 62803 (2017)
Otsu Change Detection of Low and Moderate Resolution Synthetic Aperture Radar Image by Using Multi-Texture Features
Ma Su, Deng Kazhong, Zhuang Huifu, and Han Yafang
Low and moderate resolution synthetic aperture radar (SAR) images are used to extract texture features with different texture window sizes by the gray-level co-occurrence matrix and construct the difference images. Otsu threshold segmentation method is combined to obtain the change image. The experimental results show Low and moderate resolution synthetic aperture radar (SAR) images are used to extract texture features with different texture window sizes by the gray-level co-occurrence matrix and construct the difference images. Otsu threshold segmentation method is combined to obtain the change image. The experimental results show that，as for the detection of areas with simple surface features and obvious changes, the low and moderate resolution SAR images can meet the high detection accuracy demand by using the mean-value texture feature in combination with the corresponding texture window..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 62804 (2017)
Reviews
Recent Advances in Cascading Electro-Optic Photonic Crystal
Jiang Haowei, Li Guangzhen, Liu Yian, Chen Yuping, and Chen Xianfeng
Controlling light based on cascading linear electro-optic effect is an effective and widely used method for light modulation. For an one-dimensional photonic crystal like periodically poled lithium niobate (PPLN), while electric field is applied parallel to the optical axis, the refractive index is periodically changedControlling light based on cascading linear electro-optic effect is an effective and widely used method for light modulation. For an one-dimensional photonic crystal like periodically poled lithium niobate (PPLN), while electric field is applied parallel to the optical axis, the refractive index is periodically changed, and an electro-optic photonic crystal is formed. While electric field is applied vertically to the optical axis, not only the size of refractive index ellipsoid is periodically changed, but also the direction of spindle of refractive index ellipsoid is periodically changed. Some of the applications based on cascading electro-optic effect are reviewed, including tunable chirality devices, all optical logic gates, temporal cloak based on simultaneous fast and slow light, and nonlinear optics. The great potential applications of the cascading electro-optic effects in integrated photonic circuit are predicted..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 60001 (2017)
Recent Advances in Multicolor Two-Photon Imaging Technique
Cui Quan, Chen Zhongyun, Zhang Zhihong, Luo Qingming, and Fu Ling
Two-photon fluorescence microscopy is a kind of nonlinear optical microscopy, which has the advantages of high time resolution, spatial resolution, high signal to noise ratio and intrinsic three-dimensional ability. Traditional two-photon fluorescence microscopy generally adopts tunable ultra-short pulse laser with pulTwo-photon fluorescence microscopy is a kind of nonlinear optical microscopy, which has the advantages of high time resolution, spatial resolution, high signal to noise ratio and intrinsic three-dimensional ability. Traditional two-photon fluorescence microscopy generally adopts tunable ultra-short pulse laser with pulsewidth of 100 fs as the light source. At present, two-photon fluorescence microscopy is further studied, and light source and detection method improvements are common means. In this paper, we introduce and summarize the recent advances in multicolor two-photon excited fluorescence microscopy and its application in biomedicine. Firstly, traditional application of femtosecond laser and optical parametric oscillator in multicolor imaging is introduced. Secondly, we focus on the application of fiber supercontinuum in multi-color microscopic imaging. Finally, we make a description of our recent work on continuum spectrum generation by enhanced self-phase modulation and selective excitation to achieve multicolor imaging. Multicolor two-photon imaging technology has the advantages of simple set-up, simple operation, and it has been broadly applied in biomedical and material science. Which provides a powerful tool and platformfor biomedical diagnosis and research..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 60002 (2017)
Research Progress on Continuous Fiber-Reinforced Metal Matrix Composites and Their Laser Cladding
Shi Chuan, Lei Jianbo, Zhou Shengfeng, Guo Jinbo, and Wang Wei
The preparation methods, microstructures and properties of continuous fiber-reinforced aluminum, magnesium and titanium matrix composites are summarized. The existing problems are pointed out and a new method of preparing the fiber reinforced metal matrix composites by laser cladding is put forward. The fibers are embeThe preparation methods, microstructures and properties of continuous fiber-reinforced aluminum, magnesium and titanium matrix composites are summarized. The existing problems are pointed out and a new method of preparing the fiber reinforced metal matrix composites by laser cladding is put forward. The fibers are embedded into the cladding powder first and then processed by laser cladding rapidly. This method can precisely control the processing parameters, reduce the processing time, and make the composites with a better performance be obtained..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 60003 (2017)
Research Progress of Algae Based on Laser Spectroscopy Technology
Qu Yingtong, Li Ying, and Guan Ranyun
Algae have an irreplaceable role in many fields. Laser Raman spectroscopy technology and laser induced breakdown spectroscopy (LIBS) technology have been widely used in various fields due to their advantages, such as no need of complicated preparation for the samples, less damaging for the sample, multi-element detectiAlgae have an irreplaceable role in many fields. Laser Raman spectroscopy technology and laser induced breakdown spectroscopy (LIBS) technology have been widely used in various fields due to their advantages, such as no need of complicated preparation for the samples, less damaging for the sample, multi-element detections simultaneously, and so on. This paper introduces recent application progress of algae research based on the laser Raman spectroscopy technology and LIBS technology, and the development prospect is discussed..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 60004 (2017)
Review for Retinal Oxygen Saturation Measurement Technology
Xian Yongli, Dai Yun, and Gao Chunming
Retinal blood oxygen measurement technology can provide reliable retinal blood oxygen metabolism information for medical diagnosis, which can stand for systemic microcirculation status. The noninvasive measurement of retinal oxygen saturation (SO2) is based on spectroscopy, which is a hot point for researchers in the fRetinal blood oxygen measurement technology can provide reliable retinal blood oxygen metabolism information for medical diagnosis, which can stand for systemic microcirculation status. The noninvasive measurement of retinal oxygen saturation (SO2) is based on spectroscopy, which is a hot point for researchers in the field of life science. While researchers overseas have done a lot of work, researchers in China are still at the threshold of this field. Existed theses are reviewed to promote research and application in this regard. We firstly introduce the basic principle of retinal oximetry, and then summarize the various techniques that have been applied to the retinal oximetry. Advantages and limitations of each are discussed. The research achievement and application situation in retinal diseases using retinal oximetry are also summarized, and major problems of retinal oximetry encountered are discussed. Lastly, future perspectives of the retinal oximetry used in life science are discussed..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 60005 (2017)
Spectroscopy
Measurement of Trace Moisture Based on Integrated Cavity at 1392 nm with High Sensitivity
Xu Dong, Wu Tao, He Xingdao, and Fang Hui
We report an off-axis integrated cavity absorption spectroscopy instrument based on distributed feedback (DFB) laser and applied it for measuring trace moisture in high purity nitrogen gas and standard methane. The light emitting from the laser centered at 1392 nm is directly focused into the cavity formed with two higWe report an off-axis integrated cavity absorption spectroscopy instrument based on distributed feedback (DFB) laser and applied it for measuring trace moisture in high purity nitrogen gas and standard methane. The light emitting from the laser centered at 1392 nm is directly focused into the cavity formed with two high reflectivity mirrors, separated by a distance of 60 cm. The output signal of the cavity is focused into the photoelectric detector. The mirror reflectivity is calibrated by that of standard methane detected at different pressures. The reflectivity of the cavity mirror is measured to be 0.99843±0.00003 at 1.599 kPa. The H2O absorption lines at 7189.344 cm-1 and 7185.597 cm-1 are respectively used for measuring trace moisture in high purity nitrogen gas and standard methane. The optimum noise-equivalent absorption coefficients of 1.65×10-8 cm-1 and 3.75×10-8 cm-1 in 200 s are achieved, respectively, which corresponded to the volume fraction detection limits of 2.28 ×10-6 and 4 ×10-6. The volume fraction detection limit can be increased by about 24 times and 19 times, respectively, reaching about 95×10-9 and 210×10-9 via the strongest absorption line at 7181.155 cm-1. The volume fraction detection limit of the system can be up to the level of 10-12 if the mirrors with a higher reflectivity and the strongest absorption line are used..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 63001 (2017)
Design and Performance Test of Practical Near Infrared Micro-Spectrometer
He Wenxin, Wen Zhiyu, and Zhou Ying
In recent years, near infrared (NIR) spectroscopic analysis has attracted wide attention and it has been researched deeply as an important method of the identification of oil components in the process of petroleum exploration. The environmental conditions in the process of petroleum exploration are severe because of hiIn recent years, near infrared (NIR) spectroscopic analysis has attracted wide attention and it has been researched deeply as an important method of the identification of oil components in the process of petroleum exploration. The environmental conditions in the process of petroleum exploration are severe because of high temperature and cramped space in reservoirs. In view of the above technical problems, this paper develops a practical NIR micro-spectrometer with the volume of 154 mm×66.5 mm×38 mm, which can continuously and stably work in high temperature condition. The NIR micro-spectrometer selects concave grating as splitting element. The holographic concave grating with high throughput, few stray light and high quality imaging is designed by theoretical calculation and Zemax software simulation for characteristic band of oil gas. The detector adopts two stage semiconductor refrigeration linear charge-coupled device (CCD) of Hamamatsu. Through reasonable optical design and compact structure layout, it can stably work in high temperature condition of 70 ℃. Then we calibrate and test performance of the spectrometer. The results show that spectral region of the NIR micro-spectrometer ranges from 1550 nm to 1890 nm, the resolution is better than 4.8 nm, the accuracy of wavelength is ±1.1 nm, and the signal-to-noise ratio is 1202∶1. Finally, we conduct the application experiment of absorbance for 0# diesel oil and water, which fully demonstrates the practical level of the system..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 6, 63002 (2017)
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