Journals >Laser & Optoelectronics Progress
Contents
2020
Volume: 57 Issue 3
34 Article(s)
Export citation format
Atmospheric Optics and Oceanic Optics
Retrieval of Fine Mode Aerosol Optical Depth Based on Satellite Polarization Remote Sensing
Jianan Gao, Liping Li, Tingwei Cui, and Chen Chen
Fine mode aerosol optical depth in Xianghe was calculated, using data from the onboard multi-angle polarization sensor POLDER-3 in the PARASOL satellite. The retrieval results were compared with the operational products of POLDER, MODIS, and AERONET data. The results show that the accuracy of POLDER using polarization Fine mode aerosol optical depth in Xianghe was calculated, using data from the onboard multi-angle polarization sensor POLDER-3 in the PARASOL satellite. The retrieval results were compared with the operational products of POLDER, MODIS, and AERONET data. The results show that the accuracy of POLDER using polarization remote sensing is significantly better than that of unpolarized MODIS. The correlation coefficient is increased from 0.67 to 0.93, and the average error is reduced from 0.32 to 0.15. As combined with the neural network (NN) method, the method gave correlation coefficient of 0.94 and standard deviation of only 0.11. Then, NN was applied to Hangzhou and Hong Kong, respectively. The verification results show that it has similar accuracy in Hangzhou but poor applicability in Hong Kong. The research shows it is feasible to use the NN to extract fine mode aerosol information from polarized signals..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 030101 (2020)
Extrinsic Calibration for Lidar and Stereo Vision Using 3D Feature Points
Shaojie Chen, Zhencai Zhu, Yonghe Zhang, Ming Guo, and Shuai Zhi
Lidar and stereo cameras are important environmental sensors for unmanned driving. Calibrating external parameters between these two sensors is an important basis for their combination; however, combining two types of information requires a complex calibration process. This paper proposes a method based on feature poinLidar and stereo cameras are important environmental sensors for unmanned driving. Calibrating external parameters between these two sensors is an important basis for their combination; however, combining two types of information requires a complex calibration process. This paper proposes a method based on feature point pair matching. Two rectangular planks are used to extract the 3D point cloud of the edge of the board in stereo vision and lidar coordinate systems, which is then used to obtain the corner coordinates. Finally, the Kabsch algorithm is used to solve the coordinate transformation between the paired feature points, and a clustering method is used to remove outliers from the multiple measurements and obtain the average value. By setting up an experiment, this method can be implemented on the Nvidia Jetson Tx2 embedded development board, and accurate registration parameters can be obtained, thus verifying the theoretical method’s feasibility. This registration method is simple and easy to execute, can automatically perform multiple measurements, and is improved compared with similar methods..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 030102 (2020)
Characteristic Analysis of Underwater Laser Propagation Based on Sahu-Shanmugam and Fournier-Forand Volume Scattering Functions
Tiansong Li, Xiang Gao, Xiaoyan Zhou, and Rongkai Yang
Combined with Sahu-Shanmugam and Fournier-Forand volume scattering functions, a simulated model of underwater laser transmission channel is built with Monte Carlo method, and the model is used to analyze the beam extension characteristics at the receiving end. The effects of received field of view and the diameter of rCombined with Sahu-Shanmugam and Fournier-Forand volume scattering functions, a simulated model of underwater laser transmission channel is built with Monte Carlo method, and the model is used to analyze the beam extension characteristics at the receiving end. The effects of received field of view and the diameter of receiver on the power density of the beam, and the distribution characteristics of beam power density under different receiving distances are studied under three typical waters. The results show: with the increase of scattering coefficient in the water area and the increase of transmission distance, the beam distribution expansion is intensified; with the increase of diameter of receiving surface, the variation trend of the beam power density decreases gradually, and the amplitude of the beam power density increases as the increasing receiving field angle; with the increase of transmission distance, the distribution of beam power density becomes more discrete. The results provide a reference for underwater positioning or underwater receiver design..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 030103 (2020)
Atomic and Molecular Physics
Dependence of Above-Threshold Ionization Spectra on Frequencies of Two-Color Laser Fields
Facheng Jin, Huihui Yang, Tong Zhang, and Yuxin Chen
Based on the frequency-domain theory in nonperturbative quantum electrodynamics, we investigate the above-threshold ionization of an atom exposed to two-color laser fields of different frequencies. As both the frequencies of two laser fields are lower than the ionization potential of the atom, the above-threshold ionizBased on the frequency-domain theory in nonperturbative quantum electrodynamics, we investigate the above-threshold ionization of an atom exposed to two-color laser fields of different frequencies. As both the frequencies of two laser fields are lower than the ionization potential of the atom, the above-threshold ionization spectrum comes from quantum interference among many ionization channels, and the two laser fields play same roles in the above-threshold ionization process. As the frequency of one of the two laser fields increases, the above-threshold ionization spectrum shows a multiplateau structure gradually, which is from the contribution of atoms absorbing different photons of high-frequency laser field. As the frequency of one of the two laser fields is much higher than the atomic ionization potential, the two laser fields play different roles in the above-threshold ionization process, where the high-frequency laser field may determine the ionization probability and the low-frequency laser field may determine the width of each plateau that can be predicted by the energy conservation relationship..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 030201 (2020)
Hyperfine Energy Level Splitting Structure Measurement of the Excited State 6D5/2 for Cesium Atom
Zhihong Wang, Jinfang Zhang, Zhaoqing Zeng, Kuizhi Yan, Haitao Zhou, and Baodong Yang
Based on the ladder-type atomic system of cesium ( 133Cs) 6S1/2-6P3/2-6D5/2, a pump light with a wavelength of 852.335 nm or 852.356 nm and probe light with a wavelength of 917.483 nm were inversely arranged in a 133Cs vapor cell at room temperature. Accordingly, a double resonance absorption spectrum of 6P3/2-6D5/2 hyBased on the ladder-type atomic system of cesium ( 133Cs) 6S1/2-6P3/2-6D5/2, a pump light with a wavelength of 852.335 nm or 852.356 nm and probe light with a wavelength of 917.483 nm were inversely arranged in a 133Cs vapor cell at room temperature. Accordingly, a double resonance absorption spectrum of 6P3/2-6D5/2 hyperfine energy level transition with narrow line-width and high signal-to-noise ratio is obtained. Subsequently, all the frequency intervals of the hyperfine energy level splitting structure of the excited state 6D5/2 are measured using a “ruler” built with an acousto-optic modulator. Finally, the hyperfine constants of magnetic dipole Ahfs and electric quadrupole Bhfs are obtained as (-4.59±0.06) and (-0.78±0.66) MHz, respectively, which agree with values reported in the literature..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 030202 (2020)
Diffraction and Gratings
Diffraction Characteristics Analysis of Cascaded Liquid Crystal Polarization Gratings
Li'na Wang, Mingqiu Li, Chunyang Wang, Hongwei Shi, and Qifeng Niu
Liquid crystal polarization grating (LCPG) can achieve non-mechanical beam steering. During the actual preparation of LCPGs, the filling of liquid crystal molecules is not uniform, resulting in uneven liquid crystal layer thickness, which reduces the diffraction efficiency of light through the same position of the effeLiquid crystal polarization grating (LCPG) can achieve non-mechanical beam steering. During the actual preparation of LCPGs, the filling of liquid crystal molecules is not uniform, resulting in uneven liquid crystal layer thickness, which reduces the diffraction efficiency of light through the same position of the effective region of cascaded LCPG. This study analyzes the influence of driving voltage on the diffraction efficiency of LCPG based on Jones matrix theory to improve the diffraction efficiency of cascaded LCPGs. An experimental device is constructed for beam deflection using a three-stage cascaded LCPGs. The spot energy is measured by applying varying driving voltages, and the relationship between the diffraction efficiency and the voltage is obtained. The experimental results show that the +1st-order diffraction efficiency reaches 0.80-0.84 when the voltage is in the range of 2.0-2.4 V..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 030501 (2020)
Sub-Wavelength Grating 1×4 Power Splitter with Beam Convergence
Cheng Huang, Chenglin Bai, Wenjing Fang, Xinye Fan, and Ximei Jiang
This paper proposes a single-layer sub-wavelength grating structure with beam convergence function and four-way beam splitting. The structure is designed and optimized using a rigorous coupled-wave analysis method and wavefront phase control principle, and the specific phase design rules are given. The simulation resulThis paper proposes a single-layer sub-wavelength grating structure with beam convergence function and four-way beam splitting. The structure is designed and optimized using a rigorous coupled-wave analysis method and wavefront phase control principle, and the specific phase design rules are given. The simulation results of the structure using finite element software COMSOL show that the structure can realize four-way splitting under irradiation of transverse magnetic (TM) polarizes light at 1550 nm wavelength. Moreover, the optical power of each beam is equal and beam convergence is realized. The calculated total transmittance is 92.670%. Thus, the sub-wavelength grating structure can be applied in the important fields of optical communication integration and spatial optical coupling..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 030502 (2020)
Fourier Optics and Signal Processing
Measurement Method of Gun’s Jump Angle Based on Improved Least-Squares
Man Jiang, Jun Wang, Bojun Du, Haifeng Wang, and Haisong Chen
Traditional methods measuring the gun’s jump angle have the disadvantages of low measurement efficiency, large error, weak practicability, and narrow measurement range. Aiming at these problems, a gun’s jump angle measurement method based on the improved least-squares algorithm is proposed. The method uses the improvedTraditional methods measuring the gun’s jump angle have the disadvantages of low measurement efficiency, large error, weak practicability, and narrow measurement range. Aiming at these problems, a gun’s jump angle measurement method based on the improved least-squares algorithm is proposed. The method uses the improved circle fitting algorithm to detect the center position of the muzzle image, and obtains the coordinates of the gun shooting target point under the calibration of the binocular cameras. The target is collimated with the center position of the muzzle image and then shot. In data processing, direction of the gun initial velocity vector is calculated and used to obtain the actual measurement result of the gun’s jump angle, combined with the center position of the muzzle image and the aiming direction of the shooting target. The experimental results show that the improved algorithm is with fewer parameters, simple objective function, and low computational complexity, and it shortens the calculation time and improves the accuracy of the muzzle image center positioning. The measurement results show that the accuracy of the measured jump angle is within 0.5', which verifies the accuracy of the jump angle measurement system..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 030701 (2020)
Geometric Optics
Phase Diversity Wavefront Detection Technique Based on Hybrid Particle Swarm Algorithm
Wenshang Xiong, and Jihong Wang
Lower-order large aberrations, such as defocusing and spherical aberrations, caused by uneven temperature distribution inside an optical telescope system and mirror thermal deformations, seriously reduce the detection capability of an optical system. Herein, a method for wavefront detection that combines the phase diveLower-order large aberrations, such as defocusing and spherical aberrations, caused by uneven temperature distribution inside an optical telescope system and mirror thermal deformations, seriously reduce the detection capability of an optical system. Herein, a method for wavefront detection that combines the phase diversity method with defocusing grating is introduced. In addition, a hybrid particle swarm algorithm that combines a linear descending weight particle swarm optimization with tabu search is proposed. The optimization performance of the algorithm is verified by simulation. Two images are acquired using a combination of the phase diversity method and defocusing grating, enabling the wavefront to thereafter be reconstructed and the wavefront aberration to be estimated by solving the objective function using hybrid particle swarm algorithm. The simulation results show that the proposed algorithm can solve the objective function for the wavefront aberration with an RMS value below 0.859λ. After optimization, the wavefront residual error reaches the order of 10 -3 and convergence is achieved after approximate 3 iterations. This result satisfies the correction accuracy of low-order large aberration..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 030801 (2020)
Instrumentation, Measurement and Metrology
Defect Detection in Mirror-Like Object Surface Based on Phase Deflection
Shuo Jiang, Linghui Yang, Yongjie Ren, and Jigui Zhu
To detect defects on mirror-like object surfaces in the modern manufacturing industry, an automatic detection method based on phase measuring deflectormetry is proposed. The phase of the reflected image is extracted by combining the phase shift and Gray code, and defects are identified by an analysis of local phase irrTo detect defects on mirror-like object surfaces in the modern manufacturing industry, an automatic detection method based on phase measuring deflectormetry is proposed. The phase of the reflected image is extracted by combining the phase shift and Gray code, and defects are identified by an analysis of local phase irregularities. In addition, the phase extraction error that leads to false detection is analyzed. A wrapped phase period index correction algorithm is proposed to prevent period misalignment during the phase unwrapping. Therefore, accurate phase extraction can be assured through the phase unwrapping algorithm, and false detection is avoided. Experimental results indicate that the proposed method can accurately and reliably detect mirror-like surface defects..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 031201 (2020)
Intensity Consistency Control Method for Multi-Wavelength Micro-Interferometry
Zhongsheng Zhai, Jiaojie Huang, Hang Zhao, Jinsong Li, Qinghua Lü, and Xuanze Wang
This study presents a method for controlling the intensity consistency of multi-wavelength micro-interferometry. A white LED with tunable intensity is used as the multi-wavelength source. A detector is placed in the micro-interferometry optical path to detect intensity of light emitted from different filters, and the sThis study presents a method for controlling the intensity consistency of multi-wavelength micro-interferometry. A white LED with tunable intensity is used as the multi-wavelength source. A detector is placed in the micro-interferometry optical path to detect intensity of light emitted from different filters, and the signal is fed back to an STM32 microcontroller in real time. Light intensities from different optical filters are quickly adjusted to be consistent using PID (proportion integration differentiation) control method and multi-wavelength interferograms with consistent gray distribution are obtained. The experimental results show that the presented method can quickly adjust the illumination intensity at different wavelengths, accurately stabilize at the set value, and reduce interferogram contrast error from 18% to 2%..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 031202 (2020)
Noise Data Processing Methods in Simulation and Training System of Bone-Setting Manipulations in Traditional Chinese Medicine
Dawei Qiu, Hui Cao, and Jing Liu
Orthopedics of bone-setting in traditional Chinese medicine (TCM) for the treatments of fractures has such characteristics as little pain, quick healing, and well recovery, which is the first choice for bone injury patients. However, the bone-setting manipulations in TCM are difficult to teach and learn, which hinders Orthopedics of bone-setting in traditional Chinese medicine (TCM) for the treatments of fractures has such characteristics as little pain, quick healing, and well recovery, which is the first choice for bone injury patients. However, the bone-setting manipulations in TCM are difficult to teach and learn, which hinders their inheritance and development. Inevitably, there will be noise data in the developed simulation and training system of bone-setting manipulations in TCM because of sensors’ qualities and transmission channels, which severely restricts the quantization, analysis, and evaluation of bone-setting manipulations in TCM. Aiming at the complexity of the bone-setting manipulations in TCM, the zeroth order, first order, and second order Kalman filtering (KF) combining velocity and acceleration vectors was proposed; meanwhile the principle of hyperparameter adjustment was determined through experiments. The proposed method is applied on the Australian Sign Language signage data set and the simulation and training system of bone-setting manipulations in TCM. The experiment results show that noise data are filtered and the details of the bone-setting manipulations in TCM are preserved well..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 031203 (2020)
Lasers and Laser Optics
Inconel 718 Coating Process for Laser Remanufacturing Three-Dimensional Forming of K418 Blades
Jie Xu, Jinyu Zhou, Weibin Ren, Yaozhong Lu, and Xianyi Xu
Controlling and optimizing the local remanufactured multilayer stereo forming microstructures of K418 thin-walled blades is a difficult task. This study investigates a laser-based remanufacturing coating process and microstructure control of K414 alloy. The alloy is coated with Inconel 718. The formation of Inconel 718Controlling and optimizing the local remanufactured multilayer stereo forming microstructures of K418 thin-walled blades is a difficult task. This study investigates a laser-based remanufacturing coating process and microstructure control of K414 alloy. The alloy is coated with Inconel 718. The formation of Inconel 718 is tested by three processes, which are used for observing the microstructure of the coating, testing mechanical properties, and then comparing, analyzing, and conducting a single-channel multilayer stereo forming test. According to the test results, the optimal coating parameters are as follows: laser power is 1.2 kW, scanning speed is 300 mm/min, powder feeding rate is 25 g/min, gas flow rate is 3 L/min, pulse width is 10 ms, and duty ratio is 1∶1. The matrix combining with a single coating forms a strong metallurgical bonding with height of 1.537 mm and width of 1.414 mm. The coating mainly consists of fine and dense equiaxed crystal dendrites, oriented columnar dendrites, and cell crystals. The microhardness of the coating is 263.7-289.7 HV0.2. The total height of a multi-layer three-dimensional formation is 3.67 mm with a microhardness range of 284.3-315.5 HV0.2. The bottom layer is coated with Laves, MC, and γ'' phases. The hardness of the bottom layer is increased by the dispersion-strengthened alloy..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 031401 (2020)
Microstructure and Corrosion Behaviors of 316L Coating Fabricated by Laser Cladding
Peng Liu, Zhikai Chen, Quanming Jin, and Qinghai Zhu
In the present study, a 316L coating is deposited on the surface of 45# steel substrate using laser cladding technology to improve the corrosion resistance of the metal parts. The hardness, microstructure, and crystal morphology of the coating are characterized by optical microscope,energy dispersive spectroscopy, scanIn the present study, a 316L coating is deposited on the surface of 45# steel substrate using laser cladding technology to improve the corrosion resistance of the metal parts. The hardness, microstructure, and crystal morphology of the coating are characterized by optical microscope,energy dispersive spectroscopy, scanning electron microscopy, microhardness tester, and other equipment. The results show that the coating exhibits good metallurgical bonding with the substrate under certain processing parameters, and that the main crystal type is austenite with the existence of a small amount of Cr23C6 in the intergranular region. The crystal dimensions of the 316L coating increase with increase in the energy density, while the hardness of the surface subsequently decreases. When the energy density is less than or equal to 19 J·mm -2, the coating is prone to spheroidization and roughening. However, when the energy density is too high, the surface of the coating will overheat, resulting in the burning of some elements. Thus, some of the elements are lost owing to the degradation in performance. Moreover, according to the analysis of corrosion morphology, the main type of corrosion failure of the 316L coating is intergranular corrosion, and a small number of corrosion pits occur in the coating as well. With increase in intergranular corrosion, the 45# steel substrate begins to corrode, leading to the formation of an oxide film..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 031402 (2020)
Analysis of Micromorphology and Mechanical Properties of Laser Cladding Nickel/Tin-Based Babbitt Alloy
Tongzhou Xu, Chen Zhang, Changqing Sun, Haitao Chen, Ling Xu, and Xiuhong Pan
A tin-based alloy cladding layer and a nickel/tin (Ni/Sn)-based alloy cladding layer are prepared using a laser cladding process. The microstructure, hardness, and friction and wear properties of the two cladding layers are analyzed and compared to those of the as-cast Sn-based Babbitt alloy. The results reveal that thA tin-based alloy cladding layer and a nickel/tin (Ni/Sn)-based alloy cladding layer are prepared using a laser cladding process. The microstructure, hardness, and friction and wear properties of the two cladding layers are analyzed and compared to those of the as-cast Sn-based Babbitt alloy. The results reveal that the prepared Sn-based alloy cladding layer comprises square-shaped SnSb, petal-like Cu6Sn5, and a matrix phase α-Sn. A mixed phase of NixSny and CuNiSb2 is formed at the bottom of the Ni/Sn-based alloy cladding layer due to Ni diffusion. The two cladding layers have similar microhardness at a cross-sectional depth of 0.1-0.7 mm and both layers have a hardness value of approximately 50 HV. As the depth of the section increases, there is an abrupt increase in the microhardness of the Ni/Sn-based alloy cladding layer because the Ni element in the transition layer diffuses to the cladding layer, forming an Sn-Ni intermetallic compound. The Sn-Ni intermetallic compound increases the microhardness of this region. The average friction coefficients of the Ni/Sn-based cladding layer and Sn-based cladding layer are 0.165 and 0.199, respectively, which are superior to that of the as-cast Sn-based Babbitt alloy. The two cladding layers have better wear and fatigue properties than the as-cast Sn-based Babbitt alloy because the wear mechanism of the former is surface fatigue wear and pitting phenomenon is found on the wear surface. On the other hand, the wear mechanism of the latter is surface fatigue wear and abrasive wear, and the surface is severely worn, which results in furrows..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 031403 (2020)
Relative Density of GH4169 Superalloy Prepared by Selective Laser Melting
Guohui Zhang, Shaoqing Guo, Shuai Huang, Biao Zhou, Taiqi Yan, Bingqing Chen, and Xuejun Zhang
Herein, selective laser melting technology is applied to preparing block samples of multiple sets of GH4169 by changing the laser power and adjusting the scanning speed. The power density of the block samples is calculated, the relative density of the prepared samples is measured, and pores and microstructures of the sHerein, selective laser melting technology is applied to preparing block samples of multiple sets of GH4169 by changing the laser power and adjusting the scanning speed. The power density of the block samples is calculated, the relative density of the prepared samples is measured, and pores and microstructures of the samples are also observed. Results show that, at a very low scanning speed, the microstructural view of the samples shows circular pores, whereas at a very high scanning speed, irregular shaped pores appear on the microstructure. The parameters suitable for the scanning process include a scanning speed of 0.9-1.5 m/s and the laser power of 260-350 W, samples having higher relative density and lesser pores can be formed, and the highest relative density is 99.7%. The microstructural morphology of the samples with high relative density is in the form of columnar dentrites. As the energy input density increases, there is a gradual refinement in the dendrite growth as well as in the stability..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 031404 (2020)
Reducing Differential Polarization Loss in Four-Frequency Differential Laser Gyroscope
Min Dang, Wendong Yu, qiang Hu, and Linfeng Chen
The bias caused by differential polarization loss directly affects the performance of four-frequency differential laser gyroscopes. This study proposes an optimization method for the configurable parameters of mirrors, and effectively reduces the differential polarization loss. Based on the Jones matrices, the self-conThe bias caused by differential polarization loss directly affects the performance of four-frequency differential laser gyroscopes. This study proposes an optimization method for the configurable parameters of mirrors, and effectively reduces the differential polarization loss. Based on the Jones matrices, the self-consistent equation is numerically solved, obtaining the influences of the mirror parameters and the non-coplanar folding angle of the four-frequency differential laser gyroscope on the differential polarization loss. The mirror configurations are then improved. In the numerical calculations, the differential polarization loss is most affected by the reflection-induced retardance of the mirror. When the sum of the reflection-induced retardances of four mirrors is 0 and the positive and negative reflection-induced retardances of four mirrors can wipe one another out, the differential polarization loss is 0. This technique will be valuable for reducing the differential polarization loss in engineering applications..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 031405 (2020)
Forming Mechanism and Performance Analysis of X65 Oil and Gas Steel Pipeline Weld Fabricated by Laser Deep-Penetration Welding
Guoye Jiang, Yuping Liu, Pu Lei, Ming Pang, Min Li, and Wei Fu
In this study, a laser deep-penetration welding experiment was conducted on an X65 steel pipeline using a Nd∶YAG laser. The morphology of the created weld was observed using a optical microscope. The microstructure of the weld area was characterized by a scanning electron microscope and its hardness was measured by a hIn this study, a laser deep-penetration welding experiment was conducted on an X65 steel pipeline using a Nd∶YAG laser. The morphology of the created weld was observed using a optical microscope. The microstructure of the weld area was characterized by a scanning electron microscope and its hardness was measured by a hardness tester. Results show that the weld depth of the steel sample decreases from 8 mm to 4 mm because of the variation in welding deflection angle, which affects the energy distribution of the laser in space. It is also observed that the weld profile deflects along the laser deflection angle in the direction of welding thickness. At the end of the welding process, a crack associated with temperature and temperature gradient is observed on the weld due to reduction in welding speed. However, as the welding speed increases, the width of the weld heat-affected zone narrows, and the maximum hardness of the weld zone increases from 472.1 HV to 565.5 HV. The asymmetry in the hardness distribution of the fusion zone increases with the increasing welding speed..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 031406 (2020)
Effect of Intensity Disturbance on Performance of Dual-Frequency Laser Coherent Detection
Jianying Ren, Huayan Sun, Yanzhong Zhao, and Laixian Zhang
Dual-frequency laser coherent detection technology is used to perform the Doppler measurement of high-speed targets. The power spectral function of the electric signal for the dual-frequency laser coherent detection with intensity disturbance can be obtained by combining the random statistical theory with Wiener-KhintcDual-frequency laser coherent detection technology is used to perform the Doppler measurement of high-speed targets. The power spectral function of the electric signal for the dual-frequency laser coherent detection with intensity disturbance can be obtained by combining the random statistical theory with Wiener-Khintchine theorem. Based on the theoretical model, the influences of beat line width and disturbance frequency on the signal power spectrum is analyzed, and the numerical simulation and experiments are conducted. The results reveal a Lorentz-type power spectrum distribution. For long-distance detection, an increase in the line width of the beat signal broadens the power spectrum. When the intensity disturbance frequency is close to the Doppler frequency shift, the power spectrum broadens and the signal amplitude decreases. In this case, the spectrum extraction process becomes more difficult, and the Doppler measurement accuracy decreases..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 031407 (2020)
Materials
Polarization Independent High Absorption Efficiency Wide Absorption Bandwidth Metamaterial Absorber
Chaosu Wang, Dafei Jiang, and Xiaowei Jiang
Based on the principle of surface plasmon slow optical waveguide, a metamaterial absorber with high absorption efficiency in the whole near infrared band is designed by using dielectric silicon (dielectric layer) and Au (metal layer). The simulation results show that the bandwidth of the absorber is the largest when thBased on the principle of surface plasmon slow optical waveguide, a metamaterial absorber with high absorption efficiency in the whole near infrared band is designed by using dielectric silicon (dielectric layer) and Au (metal layer). The simulation results show that the bandwidth of the absorber is the largest when the thicknesses of the metal layer and the dielectric layer are 0.04 μm and 0.02 μm, respectively. It is also found that the width of the waveguide layer and the number of absorber layers have great influence on the absorption bandwidth. Finally, it is calculated that the absorption efficiency of the metamaterial absorber can be maintained over 90% in the whole near infrared band when the incident angle of light is below 40° under TM polarization. Moreover, the absorption efficiency for TE and TM polarizations is equal at normal incidence, which shows that the metamaterial absorber designed in this paper is polarization independent..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 031601 (2020)
Medical Optics and Biotechnology
Tongue Diagnosis Method Based on Comparative Analysis of Tongue Image Chromatography
Wenwen Shang, Yawei Wang, Shuangshuang Xue, Guangwei Peng, Hao Han, and Yuanyuan Xu
Traditional tongue diagnosis information is mainly obtained by clinical subjective judgment, lacking objective and quantitative measures. Moreover, complexity of the patient self-state also affects accuracy of the diagnostic results. In this regard, a diagnostic method under the comparative analysis of self-tongue imagTraditional tongue diagnosis information is mainly obtained by clinical subjective judgment, lacking objective and quantitative measures. Moreover, complexity of the patient self-state also affects accuracy of the diagnostic results. In this regard, a diagnostic method under the comparative analysis of self-tongue image chromatography is proposed. That is, use image processing techniques to overlay positive films of healthy tongue images and colored negative films of unhealthy tongue images, select the information sensitive area of the tongue images, collect the data, use the conversion relationship between RGB and CIE Lab color model, obtain the discrete chromatography distribution characteristics, and combine the quantitative parameter range to diagnose the health state. Through simulation and experimental analysis, the feasibility and correctness of the method are verified. The method proposed can effectively improve the tongue image diagnosis effect and is useful for the further development of tongue diagnosis in traditional Chinese medicine..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 031701 (2020)
Optical Design and Fabrication
Response Time of Flow Transient Process of Magnetorheological Finishing
Hang Yang, Shupiao Song, Shuai Zhang, Huan Gan, Wen Huang, and Jianguo He
In this paper, a multiphase particle flow model of the transient process of magnetorheological finishing (MRF) has been proposed. The mechanical relations of the transient processes are obtained at macroscopic, mesoscopic, and microscopic levels. A transient process characterization method based on three-direction in sIn this paper, a multiphase particle flow model of the transient process of magnetorheological finishing (MRF) has been proposed. The mechanical relations of the transient processes are obtained at macroscopic, mesoscopic, and microscopic levels. A transient process characterization method based on three-direction in situ mechanical signals has also been proposed. The three-direction mechanical signals of the MRF are synchronously and dynamically measured in situ. The problem of in situ measurements of the liquid-solid interface of the MRF in millimeter-scale space is solved. The high removal rate finishing fluid with a yield strength of 220 kPa and a Bingham viscosity of 0.07 Pa·s is used to conduct the MRF experiment on a BK7 ultra-precision planar element of ?50-mm, and the transient response time of the MRF flow is identified to be 700 ms..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 032201 (2020)
High-Precision ITO Electrode Wet Etching Technology Based on Maskless Lithography
Yi Yin, Zhijian Liu, Saijie Wang, Sen Wu, Zhijun Yan, and Xinxiang Pan
Indium-tin-oxide (ITO) conductive films provide low resistivity, good light transmittance, and high temperature resistance; they have important applications in the field of optoelectronics. The size of the ITO electrode obtained by the existing process method is generally 10-200 μm, which limits the application of the Indium-tin-oxide (ITO) conductive films provide low resistivity, good light transmittance, and high temperature resistance; they have important applications in the field of optoelectronics. The size of the ITO electrode obtained by the existing process method is generally 10-200 μm, which limits the application of the ITO electrode in the field of micro-nano technique. This work discusses the development of a fabrication method based on the traditional wet etching process and high-precision exposure of ITO glass surface photoresist by maskless lithography. The exposure, development, and etching processes are optimized to obtain an electrode with only 2-μm width. The developed electrode has the advantages of high linearity, no undercut, and small error, thus providing a realistic reference for the application development of ITO electrode in the micro-nano field..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 032202 (2020)
Design and Realization of Fiber End Lamp Based on Fiber Optic Lighting Technology
Jiahong Chen, Xiaoren Shan, and Panfeng Ding
To apply fiber bundle end illumination to a uniformly illuminated scene, a fiber end lamp based on fiber optic lighting technology is designed, and a principle model lamp is presented. Based on the light-guiding characteristics of the fiber, a coupling device between an LED and fiber bundle is designed. Through an erroTo apply fiber bundle end illumination to a uniformly illuminated scene, a fiber end lamp based on fiber optic lighting technology is designed, and a principle model lamp is presented. Based on the light-guiding characteristics of the fiber, a coupling device between an LED and fiber bundle is designed. Through an error analysis, the best-fitting order of the algebraic polynomial fitting distribution curve is taken as 10, and the optical lens of the fiber bundle end is designed by the clipping method. The fiber bundle and lens are then assembled into a lamp. The simulations show that the vertical uniformity of illumination of a map placed on a receiving plane 300 mm away is 90.99%, the horizontal uniformity of illumination is 89.59%, and the coupling efficiency of the device is 87%. Finally, the error analysis shows that the best coupling distance of the system is 2 mm, the distance between the lens and light-emitting end face is 50 mm, and the uniformity of illumination of the lamp is 81.54%.The theoretical and experimental results show that the optical lens significantly improves the divergence characteristics and uniformity of the fiber end beam. The design method for the fiber end lamp provides a practicable solution for the application of fiber end illumination in uniform illumination design..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 032204 (2020)
Optical Devices
Linear Frequency-Modulated Signal Generation Based on Optoelectronic Oscillator Combined with Electrical Frequency-Selected Cavity
Li Liu, Jinlong Yu, Ju Wang, Chuang Ma, Tianyuan Xie, Yang Yu, Jie Fang, and Haitao Peng
A scheme of linear frequency-modulated signal generation based on optoelectronic oscillator combined with electrical frequency-selected cavity is proposed. The electrical frequency-selected cavity is composed of the electrical amplifier, attenuator, and phase shifter. By adjusting the bias voltage of the phase shifter A scheme of linear frequency-modulated signal generation based on optoelectronic oscillator combined with electrical frequency-selected cavity is proposed. The electrical frequency-selected cavity is composed of the electrical amplifier, attenuator, and phase shifter. By adjusting the bias voltage of the phase shifter in the electrical frequency-selected cavity and utilizing the frequency pulling effect between the output signal of optoelectronic oscillator and the output signal of electrical frequency-selected cavity, the linear frequency-modulated signal with a central frequency of 8.3 GHz can be produced, for which the frequency range is as large as 550 MHz, the tuning rate reaches about 5.5 MHz/μs, and the time-bandwidth product is up to 5.5×10 4 (bandwidth 550 MHz, duration 100 μs). Its phase noise depends on phase noise performance of the optoelectronic oscillator, and the frequency range depends on the bias voltage range of the phase shifter. Compared with current methods, the system structure is relatively simple. Linear frequency-modulated signal generated by this scheme has high spectral purity, and its low phase noise is -116 dBc/Hz@10 kHz..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 032301 (2020)
Optics in Computing
Three-Point Light Pen Measurement Method Based on Light Field Imaging
Zhijing Yu, Jianwen Zheng, Yongkui Tao, and Jun Wu
Because the existing three-point light pen measurement system using pespective-three-point(P3P) algorithm to solve an equation is prone to the problem of multiple solutions, this paper proposes a three-point light pen multi-solution elimination algorithm based on light field imaging. First, high-precision internal refeBecause the existing three-point light pen measurement system using pespective-three-point(P3P) algorithm to solve an equation is prone to the problem of multiple solutions, this paper proposes a three-point light pen multi-solution elimination algorithm based on light field imaging. First, high-precision internal reference calibration is performed for the central aperture of the light field camera. Second, the image is acquired by the light field camera, and the camera coordinates of the two sets of light pen laser points in the extracted central subaperture image are obtained by using the P3P algorithm. The Gaussian imaging formula is used to calculate the depth values of the two sets of solutions, and then the regional window light field is refocused to the two sets of depth planes. Finally, the appropriate sharpness evaluation method is selected to compare the sharpness of the two images, and the final light pen pose matrix is obtained to solve the three-dimensional coordinates of the pen tip. In this paper, the moving distance of the precision three-axis translation stage is selected as the comparison benchmark. The experimental results show that the maximum position differences between the experimental measurement system and the three-axis translation stage in X, Y, and Z directions are 0.35, 0.40, and 0.54 mm, respectively. At the same time, the same positive results are obtained by using four-point re-projection, which proves the validity and accuracy of the proposed method..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 032001 (2020)
OPTOELECTRONICS
Ion Beam Polishing Equivalent Removal and Polishing Experiments
Yuning Wang, Shilei Jiang, Guobin Sun, Weiguo Liu, and Xiaogang Dang
To improve the surface accuracy of the optical elements, the ion beam removal function was accurately fitted. Taking the root mean square (RMS) value of the removal function as the analysis object, the removal and fluctuation amount of the ion beam equivalent removal under different stacking spacings were analyzed. TheTo improve the surface accuracy of the optical elements, the ion beam removal function was accurately fitted. Taking the root mean square (RMS) value of the removal function as the analysis object, the removal and fluctuation amount of the ion beam equivalent removal under different stacking spacings were analyzed. The feasibility of one-dimensional equivalent removal was verified on ground of theoretical and experimental data analysis, and the optimal stacking spacing was σ. With σ as the stacking spacing, the theoretical and experimental analyses of two-dimensional equivalent removal were carried out. Fused silica was used for 30 s two-dimensional equivalent removal experiments, and the removal value was 384.7 nm. The surface modification of fused silica plane window glass with the RMS of 138.5 nm (Φ100 mm) was carried out in combination with polishing experiment. The RMS was 18 nm after processing and the surface convergence rate reached 7.82..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 032501 (2020)
OTHER AREAS of OPTICS
Statistical Characteristic Law of Average Deviation of Solar Elevation in Different Regions
Xingqing Zhang, Fang Pang, Weiping Lu, and Mengxiang Tan
In order to grasp the accuracy of solar radiation data from earth system simulation and remote sensing ground object inversion, it is necessary to discuss the regional representation of solar elevation caused by scale effect and the method for determining the data density of solar elevation. The calculation method of aIn order to grasp the accuracy of solar radiation data from earth system simulation and remote sensing ground object inversion, it is necessary to discuss the regional representation of solar elevation caused by scale effect and the method for determining the data density of solar elevation. The calculation method of average deviation of regional solar elevation is designed and the sample data with reasonable distribution is established. The average deviation of regional solar elevation is calculated with the sample data selected according to the calculation method. Its regular characteristics are summarized according to the established statistical method. According to the statistics, the average deviation of regional solar elevation is substantially correlated with the regional diameter, they are nearly linear relation of positive correlation, and the linear coefficient slightly decreases with the increase of the regional diameter. When the regional diameter is less than 3000 km, the deviation has positive linear relation with the regional diameter with the coefficient of (1.8969-1.9084)×10 -3 (°)·km -1. The dispersion degree of the average deviation of solar elevation in the region with the same width is very small. The results show that the statistical law is simple, with high stability and high reliability. The scientific evidence is provided for determining the data density of solar elevation in the regional or global earth system simulation and ground object inversion..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 033501 (2020)
Reviews
Research Progress on Flexible Photonic Materials and Devices
Yuting Ye, Hui Ma, Chunlei Sun, Zequn Chen, Jianghong Wu, Yiqi Chen, Ye Luo, Hongtao Lin, and Lan Li
Flexible photonic devices, which are bendable, foldable, and even stretchable, are not limited to the rigid physical state constraints of traditional optoelectronic devices and thus unique tunable optoelectronic properties could be achieved, which greatly expands the development and practical implementation of traditioFlexible photonic devices, which are bendable, foldable, and even stretchable, are not limited to the rigid physical state constraints of traditional optoelectronic devices and thus unique tunable optoelectronic properties could be achieved, which greatly expands the development and practical implementation of traditional optoelectronic devices. Combining with new functional optical materials, novel device integration technologies, and the advantages of photonic devices over electronic devices in material sensing specificity, channel capacity, and resistance to electromagnetic interference, flexible photonic devices show great research and application value in emerging and interdisciplinary fields such as wearable sensing, high-speed optical interconnect, light field manipulation, and optogenetic applications in biology. However, challenges including the fabrication difficulties, mechanical flexibility limitation, and the degree of integration exist in current flexible photonic technologies. This paper briefly reviews the recent progress on flexible photonic materials and devices to address those challenges. And further development and application demonstration for the flexible photonics has also been summarized and discussed..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 030001 (2020)
Quantitative Analysis of Surface-Enhanced Raman Scattering Based on Internal Standard Method
Haojian Xing, Zenghe Yin, Jie Zhang, and Yong Zhu
Surface-enhanced Raman scattering (SERS) is a highly efficient molecular spectroscopy technique widely used to detect trace species in studies in many fields such as chemistry, life sciences, and pharmaceutical analysis. However, the non-uniformity of “hot spots,” instability of chemical effects, and uncertainty of theSurface-enhanced Raman scattering (SERS) is a highly efficient molecular spectroscopy technique widely used to detect trace species in studies in many fields such as chemistry, life sciences, and pharmaceutical analysis. However, the non-uniformity of “hot spots,” instability of chemical effects, and uncertainty of the number of molecules increase the volatility of Raman signals, which presents difficulty in their use for quantitative analysis. This paper introduces the principle of an internal standard method, improvement of substrate performance, and the modes for adding three internal standards, including external addition mode, core-internal standard-shell modes, and self-calibrating substrate mode, from the following four aspects: “hot spot” effect, chemical effect, molecular adsorption, and internal standard addition mode..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 030002 (2020)
Review on Influencing Factors of Laser Rock Drilling Technology
Bing Guan, Shibin Li, Ligang Zhang, and Shuangqing Chen
Laser rock drilling technology is a new drilling technology that utilizes the advantages of high-energy laser to achieve high-efficiency and controllable destruction of complex lithologic rock formations. It exhibits great development potential in oil and gas exploitation and mining excavation. However, current researcLaser rock drilling technology is a new drilling technology that utilizes the advantages of high-energy laser to achieve high-efficiency and controllable destruction of complex lithologic rock formations. It exhibits great development potential in oil and gas exploitation and mining excavation. However, current research on laser rock drilling technology is based on indoor experiments and theoretical explorations; therefore, many challenges are to be overcome prior to its industrial application. This paper focus on the objects involved in the interaction between laser and rock, and the results on the influencing factors of rock removal by laser are summarized. Furthermore, the influence mechanism of laser parameters, rock properties, laser transfer medium, and the working environment are analyzed. Moreover, certain suggestions aiming at solving the existing problems and indicating future research directions in laser rock drilling technology research are presented. Numerous studies show that numerous different kinds of factors have different mechanisms for rock removal by laser. The quantification of the multi-factor influencing mechanism of rock removal by laser, the screening of the key influencing factors, and the coordination of the multi-factor interaction constitute the important subjects of the laser rock drilling technology applications..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 030003 (2020)
Scattering
Stray Light Suppression of Space Off-Axis Reflective CCD Camera
Ke Li, Yuanyuan Wang, Junlei Chang, Qinglin Li, Nan Zhang, Tingcheng Zhang, and Lin Yao
The stray light from a space off-axis reflective CCD camera is analyzed. The irradiance images of CCD are obtained and decomposed. The path of stray light which occupies more energy of irradiance images is determined. According to the results of optical simulation, stray light suppression measures for two imaging channThe stray light from a space off-axis reflective CCD camera is analyzed. The irradiance images of CCD are obtained and decomposed. The path of stray light which occupies more energy of irradiance images is determined. According to the results of optical simulation, stray light suppression measures for two imaging channels are proposed and optimized. After re-simulation, the veiling glare indexes of the two imaging channels are greatly reduced. According to the observation object of the camera, the point source transmission (PST) is used to test the effectiveness of stray light suppression measures. When the off-axis angle is 30°, the PST of the camera reaches the order of 10 -8, which meets the design requirements..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 032902 (2020)
Spectroscopy
Infrared Spectrum Baseline Correction Method Based on Improved Iterative Polynomial Fitting
Zhiqiang Ning, Jiaxiang Liu, Yue Wu, Mengqi Tao, and Yonghua Fang
The baseline of an infrared spectrum will drift when a Fourier transform infrared spectrometer is used to detect pollution gases. An infrared spectral baseline correction method based on improved iterative polynomial fitting is proposed in this paper. The method automatically identifies characteristic spectral peaks anThe baseline of an infrared spectrum will drift when a Fourier transform infrared spectrometer is used to detect pollution gases. An infrared spectral baseline correction method based on improved iterative polynomial fitting is proposed in this paper. The method automatically identifies characteristic spectral peaks and subsequently cuts off the characteristic peaks from the spectrum. Then, it uses the bilateral threshold to iteratively fit the infrared spectrum to obtain the best-fitting baseline. The proposed method was verified using the simulated and measured spectra of trichloroethane and ammonia, and the results were compared with those obtained by the three common polynomial fitting methods. The results show that the characteristic peaks of the corrected spectra are more obvious and the baseline is more gradual after baseline correction using proposed method. The simulation and measured data show that our baseline correction method improves the accuracy of the existing polynomial fitting baseline correction method and exhibits good performance..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 033001 (2020)
Thin Films
Surface Roughness and Scattering Characteristics of TiO2 Thin Film
Jinze Liu, Yongqiang Pan, Da Zhang, and Yanzheng Fan
A TiO2 thin film with an optical thickness of λ/4 is plated on K9 glass using the electron beam thermal evaporation technique. The effect and mechanism of different deposition rates and deposition angles on the scattering loss of TiO2 thin films are investigated. The surface roughness and bidirectional reflection distrA TiO2 thin film with an optical thickness of λ/4 is plated on K9 glass using the electron beam thermal evaporation technique. The effect and mechanism of different deposition rates and deposition angles on the scattering loss of TiO2 thin films are investigated. The surface roughness and bidirectional reflection distribution function of the TiO2 thin film before and after plating are measured using TalysurfCCI white light interference surface profiler and Horos scattering instrument. The results show that the surface roughness of the TiO2 thin film decreases as the deposition rate increases and eventually reaches 0.88 nm, which is less than the bare substrate surface roughness of 1.5 nm. This indicates that the TiO2 thin film can reduce the surface roughness of the substrate, and it is capable of smoothing the substrate. As the incident deposition angle increases, the surface roughness of the film gradually increases. When the deposition angles are 0° and 20°, the surface roughness of the film is less than that of the substrate; when the deposition angles are 40° and 60°, the surface roughness of the film is greater than that of the substrate. A positive correlation exists between the amount of surface scattering of the film and the surface roughness. Experimental data agree with theoretical calculations. When the surface roughness of the film is less than that of the substrate, the surface scattering of the film is lower than that of the bare substrate. Thus, TiO2 thin films can reduce surface scattering from the substrate..
Laser & Optoelectronics Progress
- Publication Date: Feb. 15, 2020
- Vol. 57, Issue 3, 033101 (2020)
© Copyright 2018-2021 | Chinese Laser Press. All Rights Reserved 沪ICP备15018463号-20