Journals >Laser & Optoelectronics Progress
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2017
Volume: 54 Issue 11
59 Article(s)
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Atmospheric Optics and Oceanic Optics
Modal Reconstruction Algorithm Based on Dynamic Region Extraction
Wen Lianghua, Yang Ping, Wang Shuai, Chen Shanqiu, Liu Wenjin, and Xu Bing
Transferring of quantization noise in algorithm implementation is tracked, which is caused by the finite sampling width of far field photodetector. The effect of quantization noise on wavefront aberration correction effect and convergence speed is analyzed. According to the changing of Strehl ratio (SR), a modal reconsTransferring of quantization noise in algorithm implementation is tracked, which is caused by the finite sampling width of far field photodetector. The effect of quantization noise on wavefront aberration correction effect and convergence speed is analyzed. According to the changing of Strehl ratio (SR), a modal reconstruction algorithm based on dynamic region extraction is presented. Numerical calculations are carried out with the wavefront which fits the Kolmogrove atmospheric turbulence power spectrum and is obtained by the simulation of 18- and 33-order Zernike terms. The results show that, under the condition of the camera sampling width of 12 bits and 33-order initial aberration, the SR is larger than 0.9, the root-mean-square value of wavefront recuperative residual is 0.058λ (λ is wavelength), and the algorithm is converged after iteration for 31 times. The proposed algorithm greatly improves the correction performance and convergence speed of the wavefront sensorless adaptive optics system and reduces the effect of the quantization noise..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 110101 (2017)
Ultraviolet Light Atmospheric Scattering Propagation Model Based on Monte Carlo Method
Wang Xiaofang, Zhang Xin, Zhang Jizhen, and Wang Lingjie
The molecules and aerosols in atmosphere have a strong scattering effect on ultraviolet light, so the ultraviolet light can propagate in atmosphere in the condition of non-line-of-sight. In the ultraviolet detection, the transmitter is close to the receiver. In order to study the propagation characteristics of ultravioThe molecules and aerosols in atmosphere have a strong scattering effect on ultraviolet light, so the ultraviolet light can propagate in atmosphere in the condition of non-line-of-sight. In the ultraviolet detection, the transmitter is close to the receiver. In order to study the propagation characteristics of ultraviolet light, a multiple-scattering model is established based on the Monte Carlo method, and the model is optimized by the point probability method. The pulse response and the energy density received by the detector in different atmosphere conditions are analyzed through simulation when the axes of transmitter and receiver are coplanar and non-coplanar. The simulation results show that the ultraviolet laser detection is different from remote target detection, and the deflection angle has a great influence on proximate target detection. When the scattering coefficient and absorption coefficient are large and the distance between the transmitter and the receiver is short, the echo signal is strong. The simulation results are helpful to understand the propagation characteristics of ultraviolet light in the atmosphere, and provide the theoretical foundation for the design of ultraviolet laser detection in the future..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 110102 (2017)
Light Intensity Characteristics of Propagation Partially Coherent Beams with Spherical Aberration in Oceanic Turbulence
Zhang Yanhong, Liu Yongxin, and Chen Ziyang
A light intensity expression of the partially coherent beam with spherical aberration propagating in the oceanic turbulence is obtained by the extended Huygens-Fresnel diffraction integral formula. Light intensity characteristics of the partially coherent beams with spherical aberration propagating in the seawater are A light intensity expression of the partially coherent beam with spherical aberration propagating in the oceanic turbulence is obtained by the extended Huygens-Fresnel diffraction integral formula. Light intensity characteristics of the partially coherent beams with spherical aberration propagating in the seawater are investigated by means of numerical calculation. Results show that the larger the mean square temperature dissipation rate χT is, the smaller the dissipation rate of turbulence kinetic energy of unit mass liquid ε is, or the larger the relative intensity of temperature and salinity fluctuations w is, the more obvious the effect of oceanic turbulence on the expansion of the beam is. The smaller the χT is, the larger the ε is, or the smaller the w is, the smaller impact of oceanic turbulence on the beam expansion is. At the same time, the smaller the coherence length of the beam is, or the greater the spherical aberration is, the more the beam spread is. However, the influences of the spherical aberration parameters on the diffusion of the laser are significantly weaker than that of the oceanic parameters when the beam propagates in the seawater..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 110103 (2017)
Atomic and Molecular Physics
Lensing Effect Induced by a Bose-Einstein Condensate Passing a Gaussian Laser Field
Wen Xin, Zhang Yuyi, and Qian Jing
On the basis of recent experiment, the focusing and leading effect of an ultra-cold Bose-Einstein condensate (BEC) is theoretically investigated when it transversely passes through a red-detuned Gaussian field. Particular attentions are paid on the focusing (or defocusing) in shape and leading (or lagging) in position On the basis of recent experiment, the focusing and leading effect of an ultra-cold Bose-Einstein condensate (BEC) is theoretically investigated when it transversely passes through a red-detuned Gaussian field. Particular attentions are paid on the focusing (or defocusing) in shape and leading (or lagging) in position of the atoms, which are induced by a red-detuned (or blue-detuned) laser field. The time-dependent motion of BEC atoms and its final status are presented under the influences of the acceleration, the dipolar interaction between atom and optical field, as well as the s-wave scattering collisions of individual atoms. In addition, the acceleration only influences position of the atoms; an attractive or repulsive s-wave interaction can bring on a strong deformation to the atoms, making them collapse or diffusion in essence. Compared to the previous experiments, the findings are well consistent in the regime of a red-detuned laser field, moreover, an extension to the blue-detuned field is predicted. The results may provide more feasible ways for studying coherent atom-light manipulations in the field of ultra-cold atoms and molecules in the future..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 110201 (2017)
Fiber Optics and Optical Communications
Temperature Characterization of Extrinsic Fiber Fabry-Perot Interferometric Sensor
Liu Jiaping, Wang Yan, and Liu Jihong
The structure and fabrication method of the extrinsic fiber Fabry-Perot interference (EFPI) sensors are introduced. The influence of different cavity lengths and reflectivities on interference spectrum of the EFPI is analyzed through Matlab simulation, and a temperature sensing model of the EFPI sensor is established. The structure and fabrication method of the extrinsic fiber Fabry-Perot interference (EFPI) sensors are introduced. The influence of different cavity lengths and reflectivities on interference spectrum of the EFPI is analyzed through Matlab simulation, and a temperature sensing model of the EFPI sensor is established. Finally, temperature characteristics of the EFPI sensors with different cavity lengths and reflectivities are researched through a comparison experiment. The results indicate that the EFPI sensor with a short cavity fiber has a higher temperature sensitivity. In addition, the EFPI sensor coated with palladium-gold film can effectively avoid the influence of temperature on interference spectrum and compensate temperature fluctuation..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 110601 (2017)
Outage Probability Analysis of Coherent Optical Communication System with Pointing Error in Exponentiated Weibull Channel
Zhou Linglin, Yun Jianping, Yang Haifeng, Liang Hexi, Shi Qianyun, and Dai Yonghong
In order to study the outage probability of spatial coherent optical communication system under the combined effect of atmospheric turbulence scintillation effect and pointing error, a coherent optical communication system model based on balanced detection is established based on the exponentiated Weibull atmospheric tIn order to study the outage probability of spatial coherent optical communication system under the combined effect of atmospheric turbulence scintillation effect and pointing error, a coherent optical communication system model based on balanced detection is established based on the exponentiated Weibull atmospheric turbulence fading channel. A probability density function of channel attenuation of the system under the combined effect of atmospheric turbulence scintillation effect and pointing error is given, and closed expressions of the system outage probability are derived. The effects of turbulence intensity, beam width and jitter deviation on the system outage probability are analyzed through the numerical simulation. The results show that the system outage probability increases with the increasing of the turbulence intensity and the decreasing of the normalized signal-to-noise ratio. The system outage probability can be decreased through increasing the beam width when the normalized signal-to-noise ratio is greater than 14 dB. In addition, the increase of the normalized signal-to-noise ratio cannot effectively reduce the outage probability of the system when the jitter deviation is greater than 2. Based on the simulation results of the proposed model, it is concluded that the appropriate beam width and jitter deviation can reduce the outage probability and improve the stability of the system..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 110602 (2017)
Beam Deflection Control Technology Based on Liquid Crystal Spatial Light Modulator
Yang He, Tong Shoufeng, Zhang Lei, Chang Shuai, Song Yansong, Zhao Xin, and Fan Xinkun
In order to realize non-mechanical beam intelligent control based on liquid crystal spatial light modulator, a test system is built with silicon-based liquid crystal spatial light modulator whose pixel number is 1920×1080. The system can obtain the single beam with large angle, high diffraction efficiency, continuIn order to realize non-mechanical beam intelligent control based on liquid crystal spatial light modulator, a test system is built with silicon-based liquid crystal spatial light modulator whose pixel number is 1920×1080. The system can obtain the single beam with large angle, high diffraction efficiency, continuous steering in space, divide the incident light beam into 2, 3, 4, 5 beams and control deflection angle of each beam separately. Phase modulation principle and theoretical model of the spatial light modulator are introduced. The beam deflection control function and the beam splitting function are verified. The light path and the principle of the test system are analyzed. Finally, we sum up the test results and put forward the suggestion and prospect..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 110603 (2017)
Image Processing
Gradient Constrained Microscopic Imaging Quality Improvement Method with Objective Lens Measurement
Huang Yilong, Zhao Jufeng, Zhang Keqi, Hua Weiping, and Cui Guangmang
Optical imaging degradation is one of the most important factors for image quality in digital optical microscopic imaging. Combined with the digital microscopic imaging system and optical objective lens measurement, a fast gradient constrained restoration method is proposed based on point spread function estimation undOptical imaging degradation is one of the most important factors for image quality in digital optical microscopic imaging. Combined with the digital microscopic imaging system and optical objective lens measurement, a fast gradient constrained restoration method is proposed based on point spread function estimation under different fields. By measuring the modulation transfer function of objective lens, the point spread function is obtained with different fields. A novel restoration approach is designed with the L0 gradient constraint as a regularized term. Meanwhile, the weight image stitching method is designed for the restoration of multiple fields. The image data with different objective lens are tested, and the evaluation methods are used for assessing the results. The results show that the gradient constrained microscopic imaging quality improvement method with the objective lens measurement is suitable for microscopic imaging system for its good restored effect and high computational efficiency, it takes only 1.62 s for the image size of 2048 pixel×1536 pixel..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111001 (2017)
Aerial Image Location of Unmanned Aerial Vehicle Based on YOLO v2
Wei Yongming, Quan Jicheng, and Hou Yuqingyang
In order to ensure the speed and accuracy rate of location, the YOLO v2 network with the best detection effect in the field of object detection in 2016 is used to make the target detection data sets with the obvious features of surface features as the object area. Through the dimension clustering of object box, classifIn order to ensure the speed and accuracy rate of location, the YOLO v2 network with the best detection effect in the field of object detection in 2016 is used to make the target detection data sets with the obvious features of surface features as the object area. Through the dimension clustering of object box, classified network pre-training, multi-scale detection training, change the candidate box filtering rules and other methods, the YOLO v2 network is improved, and it can better adapt to the location task. The network is able to locate the object area in the aerial image acquired from the unmanned aerial vehicle in real time. And the latitude and longitude of unmanned aerial vehicle are obtained by the projection relationship and coordinate transformation. The experimental results show that the proposed method can achieve better effect, and the average accuracy rate of the detection network increases to 79.5% in the object area detection task of the aerial image. It is verified by simulation experiment of simulated flight, the accuracy rate of the network location is over 84% in the aerial image that contains the object area..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111002 (2017)
Fusion Method of Visible and Infrared Images Based on Multi-Scale Decomposition and Saliency Region Extraction
Xu Lei, Cui Guangmang, Zheng Chenpu, and Zhao Jufeng
The fusion technique of visible and infrared images has important significance in enhancing the information richness of the imaging areas. A fusion algorithm of visible and infrared images based on the multi-scale decomposition and saliency region extraction is proposed. The edge-preserved image smoothing algorithm is The fusion technique of visible and infrared images has important significance in enhancing the information richness of the imaging areas. A fusion algorithm of visible and infrared images based on the multi-scale decomposition and saliency region extraction is proposed. The edge-preserved image smoothing algorithm is introduced to build the framework of multi-scale image decomposition. The source image is decomposed into base layer image and several detail layer images with different decomposition scales. Meanwhile, the saliency region maps are extracted in each decomposition layer combined with the guided filter. The final fusion image is obtained by the reconstruction of each decomposition layer with different weighting factor values in order to enhance the visual effect of the fusion information. The contrast experiments of objective and subjective evaluation are developed on different fusion algorithms and databases. The experimental results illustrate that the proposed algorithm has a superior objective and subjective evaluation performance on the fusion results. The fusion effect of algorithm is excellent and the applicability is good..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111003 (2017)
Band Selection Based on Local Joint Skewness and Kurtosis for Hyperspectral Image
Wang Qi, Yang Guang, Zhang Jianfeng, and Xiang Yingjie
The non-Gaussian of the hyperspectral image can be well expressed by skewness and kurtosis, which highlight the target, texture and other anomaly information. They can be well applied to the band selection. In order to stand out the partial anomaly information better, the local joint skewness and kurtosis-based band seThe non-Gaussian of the hyperspectral image can be well expressed by skewness and kurtosis, which highlight the target, texture and other anomaly information. They can be well applied to the band selection. In order to stand out the partial anomaly information better, the local joint skewness and kurtosis-based band selection for hyperspectral image is proposed on the basis of the global joint skewness-kurtosis figure. The bands of the original image are divided by the global joint skewness-kurtosis index into several subspaces. Then the template window of appropriate size is chosen and the local joint skewness-kurtosis index is calculated. All bands are traversed by this method. Finally, the accumulated local joint skewness-kurtosis index is calculated in order to complete the band selection. The band selection results show that the bands selected by the local joint skewness-kurtosis method are more widely distributed and the effect is better. The anomaly detection and fusion results show that the image obtained by the proposed method has great advantages in the evaluation of objective indicators..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111004 (2017)
Super-Resolution Reconstruction of Image Based on Optimized Convolution Neural Network
Wang Min, Liu Kexin, Liu Li, and Yang Runling
Compared with the previous two types of single-frame image super-resolution reconstruction algorithm, the super-resolution with convolution neural network (SRCNN) has greatly improved the operational efficiency and recovery accuracy with its end-to-end mapping structure. However, the number of hidden layers and the conCompared with the previous two types of single-frame image super-resolution reconstruction algorithm, the super-resolution with convolution neural network (SRCNN) has greatly improved the operational efficiency and recovery accuracy with its end-to-end mapping structure. However, the number of hidden layers and the convergence performance of the network make the recovery effects of some images worse than the example-based reconstruction algorithms. In view of the problem of network optimization, the algorithm of combining particle swarm optimization (PSO) with SRCNN is proposed. PSO is used to initialize the network weight and the gradient descent (GD) algorithm is used to correct the weight which can combine the global search capability of PSO and the local search ability of GD. The experimental results of set5, set14 datasets and the blurred images under haze weather respectively show that the proposed algorithm can not only use less parameters to obtain higher performance network, but also has better reconstruction effect than the existing four algorithms, and the ability to sharpen edges is stronger..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111005 (2017)
Hyperspectral Image Classification Based on Principal Component Analysis and Local Binary Patterns
Ye Zhen, and Bai Lin
Two kinds of hyperspectral image classification algorithms based on principal component analysis and local binary patterns are proposed. The principal component analysis is employed to reduce the redundant information in spectral domain. Following that, the local binary patterns are studied to analyze the spatial textuTwo kinds of hyperspectral image classification algorithms based on principal component analysis and local binary patterns are proposed. The principal component analysis is employed to reduce the redundant information in spectral domain. Following that, the local binary patterns are studied to analyze the spatial texture features. And the sparse presentation classification and support vector machine are used for a classification of extracted results, respectively. Combining the principal component analysis with the local binary patterns for extracting the features of hyperspectral image, we ensure that the spectral redundant information is reduced effectively, and the spatial local neighborhood information is protected. Hence, the proposed algorithms can not only sufficiently excavate spectral-spatial features of hyperspectral image for improving classification accuracy and Kappa coefficient, but also have outstanding classification performance in Gaussian noise environments and small-sample-size condition..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111006 (2017)
Imaging Systems
Infrared Dim Target Detection Based on Improved Particle Swarm Optimization Algorithm
Yao Chengqian, and Chen Wei
In order to improve the detection effect of the infrared dim target, an improved particle swarm optimization algorithm is proposed. Firstly, a quantum-behaved particle swarm algorithm is optimized based on the Gaussian distribution attraction factor, and the particle swarm mapping is optimized by the logistic chaos whiIn order to improve the detection effect of the infrared dim target, an improved particle swarm optimization algorithm is proposed. Firstly, a quantum-behaved particle swarm algorithm is optimized based on the Gaussian distribution attraction factor, and the particle swarm mapping is optimized by the logistic chaos which can avoid the later evolution into the local optimum. Secondly, the reliability of the chaotic quantum-behaved particle swarm optimization algorithm is ensured according to the diversity determined by the average Euclidean distance of the particle swarm in the later stage. Finally, the infrared dim target is detected under the minimum mean variance criterion, and the prediction value is corrected which can ensure the validity of the detection. The experimental results show that the proposed algorithm is effective in detecting infrared dim targets with the largest signal noise ratio value, and the detection probability and false alarm probability are better than other algorithms..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111101 (2017)
Image Quality Evaluation and Analysis of Zero-Order Diffraction Elimination Method in Terahertz Off-Axis Digital Holography
Wang Zewen, Li Qi, and Yuan Jing
In terahertz off-axis digital holography, the zero-order diffraction will still cause bad effects on the reconstructed image, as a result of short recording and reconstruction distance. Using three image quality objective evaluation indexes, the reconstructed images are compared and analyzed. The images are obtained byIn terahertz off-axis digital holography, the zero-order diffraction will still cause bad effects on the reconstructed image, as a result of short recording and reconstruction distance. Using three image quality objective evaluation indexes, the reconstructed images are compared and analyzed. The images are obtained by using the complex-wave retrieval method and the Laplacian operator method to eliminate the zero-order diffraction in 2.52 THz off-axis digital holography. Besides, the simulation target is designed with resolution chart in the actual imaging experiment. The hologram is simulated according to the intensity distribution of illumination light and reference light got from the real experiment, then the angular spectrum method is used to reconstruct the hologram. Finally, the corresponding processing is also performed to the hologram in the real terahertz digital holography experiment, and the results fit well with the simulation conclusions. Both methods have good suppression of zero-order diffraction. Compared with the Laplacian operator method, the complex-wave retrieval method has a higher brightness attenuation rate of zero-order diffraction, and the reconstructed image of it has higher peak signal to noise ratio overall. What′s more, it has higher signal to noise ratio in 0.2 mm bright vertical stripe area with high resolution, and the image quality is better..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111102 (2017)
Compressive Imaging Method Based on CCD Image Sensor
Zhang Shufang, Zhu Binhua, and Li Rui
The signal acquisition and compression can be made simultaneously and the signal sampling rate is much lower than the Nyquist frequency in the compressive sensing theory, which provides the possibility for high resolution imaging from low resolution sampling data. A compressive imaging method based on CCD image sensor The signal acquisition and compression can be made simultaneously and the signal sampling rate is much lower than the Nyquist frequency in the compressive sensing theory, which provides the possibility for high resolution imaging from low resolution sampling data. A compressive imaging method based on CCD image sensor is proposed. By using the unrepeatable characteristic of the serial output analog pixel value of the CCD image sensor in a single measurement, the semi cyclic and semi random measurement matrices are constructed to compress and measure the analog values outputted by CCD image sensor. Then the total variational algorithm based on augmented Lagrangian (TVAL3) arithmetic is used to decompress and reconstruct the image. This imaging method is good at measuring the sparsity of the matrices, and the original images can be well recovered. The proposed method can greatly alleviate the burden of analog digital and the complexity of quantization coding, which also has a simple structure and strong practicability. Simulation results show that the reconstructed image has better subjective and objective quality with the proposed method..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111103 (2017)
Imaging Analysis of Infrared Thermal Imaging System Based on Sea-Sky Model
Shao Long, Bai Tingzhu, Zheng Haijing, Zhang Shuo, and Chen Ying
The sea-sky atmospheric model is proposed based on the sea-sky infrared image, and the contrast transfer function of the atmospheric environment on the imaging of infrared thermal imaging system is analyzed. Taking the infrared thermal imaging system as an example, the atmospheric contrast transfer function of the slanThe sea-sky atmospheric model is proposed based on the sea-sky infrared image, and the contrast transfer function of the atmospheric environment on the imaging of infrared thermal imaging system is analyzed. Taking the infrared thermal imaging system as an example, the atmospheric contrast transfer function of the slant path in the sea-sky atmospheric model is calculated. The effects of the observation distance, atmospheric density, target altitude, atmospheric path radiation, and path zenith angle on atmospheric contrast transfer function are analyzed. The experimental results show that the observation distance, atmospheric density, atmospheric path radiation, and zenith angle of the atmospheric transmission path are inversely proportional to the atmospheric contrast transfer function. The results can be used to estimate the atmospheric impact during the practical application of the infrared thermal imaging system, and provide the basis for improving the imaging performance of the infrared thermal imaging system..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111104 (2017)
Information
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Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 113601 (2017)
Instrumentation, Measurement and Metrology
Comparative Study on In-Situ Infrared Thermometry of GaN Epitaxy on Different Substrates Prepared by MOCVD
Yang Chaopu, Song Yafeng, Fang Wenqing, Liu Mingbao, Li Chun, and Zhang Meili
The apparent temperature errors caused by emissivity indexes of 940 nm monochromatic thermometry, 1550 nm monochromatic thermometry and 940 nm/1550 nm colorimetric thermometry and deviation between the actual temperatures and apparent temperatures are theoretically compared based on infrared thermometry principle, filmThe apparent temperature errors caused by emissivity indexes of 940 nm monochromatic thermometry, 1550 nm monochromatic thermometry and 940 nm/1550 nm colorimetric thermometry and deviation between the actual temperatures and apparent temperatures are theoretically compared based on infrared thermometry principle, film equal thickness interference model and relative optical properties. These are conducted during preparation of 10 μm GaN epitaxy wafer on Al2O3, SiC and Si by using metal-organic chemical vapor deposition (MOCVD) technique. Moreover, the results of 940 nm monochromatic thermometry and 940 nm/1550 nm colorimetric thermometry of the blue light emitting diode (LED) epitaxial wafer with InGaN/GaN multiple quantum wells (MQW) structure growing on silicon (111) substrate verify the correctness of the modeling and the computation. The study result shows that the distinction of apparent temperature error coefficients with the same thermometry on different substrates is small in the range from 500 ℃ to 1300 ℃. The error coefficient with the same substrates from small to large are colorimetric thermometry, 940 nm monochromatic thermometry and 1550 nm monochromatic thermometry. Deviation between the actual temperatures and apparent temperatures on the different substrates with the same thermometry is large. The deviation with the same substrates from small to large are colorimetric thermometry, 1550 nm monochromatic thermometry and 940 nm monochromatic thermometry. This computational method and conclusion can be used for reference to develop the infrared thermometry device and choose the thermometry of the GaN epitaxy on different substrates..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111201 (2017)
Influence of Radiation Pressure Parameters on Orbit Accuracy of Jason-2 Satellite Orbit Determination Based on Satellite Laser Ranging
Gui Weizheng, Zhang Xiaoqiang, and Sheng Chuanzhen
Radiation pressure perturbation model is one of the main error sources of satellite dynamics model. Taking radiation pressure parameters into consideration or not affects the accuracy of orbit estimation while determining the orbit. Based on the radiation pressure perturbation theory, Jason-2 satellite dynamics orbit iRadiation pressure perturbation model is one of the main error sources of satellite dynamics model. Taking radiation pressure parameters into consideration or not affects the accuracy of orbit estimation while determining the orbit. Based on the radiation pressure perturbation theory, Jason-2 satellite dynamics orbit is determined by using the statistical orbit determination method and observations of 8 satellite laser ranging (SLR) stations in this paper. The influence of taking radiation pressure parameters into consideration or not on orbit accuracy is quantitatively analyzed with three evaluation methods: inner accord accuracy, outer accord accuracy, overlapping arc evaluation. The result shows that the satellite orbit calculated by estimating one group radiation pressure parameters in three days is more accurate than the one without estimating radiation pressure parameters, and the change of the orbit parameters is more stable..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111202 (2017)
Integrated Optics
Influence of Optical Path Difference on Transmission Characteristics of Coupled Double-Ring Resonators
Liu Xin, and Kong Mei
Influence of optical path difference on the transmission spectra of coupled double-ring resonators (CDRR) is analyzed, and the transmission spectra of CDRR are compared with those of single-ring resonators. The influence of double-ring optical path variation on the structural transmission characteristics is revealed. TInfluence of optical path difference on the transmission spectra of coupled double-ring resonators (CDRR) is analyzed, and the transmission spectra of CDRR are compared with those of single-ring resonators. The influence of double-ring optical path variation on the structural transmission characteristics is revealed. The results show that when the double-ring optical paths are different, two asymmetrical resonant peaks, one narrow and one wide, are generated regardless of whether the splitting condition is satisfied. The two peaks correspond to the resonances of the light in the rings that are far from and close to the bus waveguide, respectively. The positions of the two resonant peaks are affected by both the transmission coefficient of the coupler between the two rings and the degree of deviation of the two-ring optical path. The study on the transmission characteristics of the CDRR with unequal ring optical paths can provide theoretical guidance for the fabrication and sensing application of CDRR..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111301 (2017)
Lasers and Laser Optics
Design and Dynamic Characteristics of an External-Cavity Semiconductor Laser Generating Wide Bandwidth Chaos
Wang Yongsheng, Zhao Tong, Wang Anbang, Zhang Mingjiang, and Wang Yuncai
A novel external-cavity semiconductor laser faced to butterfly packaging which can generate wide bandwidth chaos is designed, and the influences of feedback ratio, injection current ratio and carrier lifetime on dynamic performance of the designed structure are investigated. Numerical simulation results demonstrate thaA novel external-cavity semiconductor laser faced to butterfly packaging which can generate wide bandwidth chaos is designed, and the influences of feedback ratio, injection current ratio and carrier lifetime on dynamic performance of the designed structure are investigated. Numerical simulation results demonstrate that diversely dynamical states including the stable state, as well as the so-called period-one, and chaotic states can be observed when the feedback ratio is adjusted or the injection current ratio is increased. The relaxation oscillation frequency of the external-cavity semiconductor laser rises with the increasing injection current ratio or the decreasing carrier lifetime. So it is much easier to generate chaotic signal with effective bandwidth of 70 GHz when the relaxation oscillation frequency and oscillation frequency of the external-cavity are at high level. The mechanism to generate such a chaos with wide bandwidth is analyzed, which provides a new source of entropy for the generation of random number. In addition, we use the relaxation oscillation of laser to cover time delay characteristics of feedback when the feedback is weak, and analyze the influence of feedback time delay on the dynamics of oscillation frequency of the external-cavity..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111401 (2017)
Forming Process of Pulsed Laser Welding with Filler Wire for Hastelloy C-276 Sheets
Xu Yuan, Wu Dongdong, and Ma Guangyi
The experiment of pulsed laser welding with filler wire on 0.5 mm thick Hastelloy C-276 sheets is conducted, and the influence rules of laser single pulse energy and defocusing on the weld joint forming are studied. The study results show that the single pulse energy and the defocusing mainly influence the heat input oThe experiment of pulsed laser welding with filler wire on 0.5 mm thick Hastelloy C-276 sheets is conducted, and the influence rules of laser single pulse energy and defocusing on the weld joint forming are studied. The study results show that the single pulse energy and the defocusing mainly influence the heat input of pulsed laser welding, spot size and spatial distribution of laser beam, and they also have a great influence on the macroscopic morphology of the weld joint forming. With the increase of the heat input, both of the top and bottom welding widths of weld joints increase, and the bottom reinforcement and the bottom contact angle of weld joints also increase. In a certain range of defocusing, the larger the laser spot diameter is, the wider the weld joint width is. With the influence of the laser beam spatial distribution, the top welding width is always slightly larger than the bottom welding width when the defocusing is negative. Under a certain process condition, the weld joints with controllable positive reinforcement, and the weld joint appearance with uniform weld width, reinforcement and contact angle, but small weld width, can be obtained. The top and bottom surfaces of weld joints are smooth and uniform, which show a feature of semicircular wave stripes..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111402 (2017)
Kilohertz Sub-Nanosecond Radially Polarized Light
Ren Junjie, Gao Xiaoqiang, and Chen Meng
Sub-nanosecond radially polarized light is obtained by using passively Q-switching of Nd∶YAG/Cr4+∶YAG bounding crystal and S-waveplate. The pulsed diode laser end pumping method with peak power of 30 W, pulse width of 120 μs, repetition frequency of 1 kHz, is used to obtain Q-switched laser pulse output with pulse widtSub-nanosecond radially polarized light is obtained by using passively Q-switching of Nd∶YAG/Cr4+∶YAG bounding crystal and S-waveplate. The pulsed diode laser end pumping method with peak power of 30 W, pulse width of 120 μs, repetition frequency of 1 kHz, is used to obtain Q-switched laser pulse output with pulse width of 878 ps and single pulse energy of 76.8 μJ. The repetition frequency instability is less than ±0.003% and the amplitude instability is less than ±3%. By inserting the polarizer and S-wave plate after bonding crystal, a sub-nanosecond radially polarized light with purity of more than 96% and single pulse energy of 27.5 μJ is obtained..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111403 (2017)
Trace Gas Measurement Method Based on Dual Wavelength Modulation of Distributed Feedback Laser
Li Zhijun, Chen Weigen, Ji Yan, Cao Lingyan, Wu Miao, Zhang Jianxue, Zhuo Li, and Yu Yonggao
In photoacoustic spectrum measurement, optical chopper is commonly used to modulate frequency of light source output signal, however, the use of optical chopper inevitably leads to the increase of noise and cost of the system. On the basis of the tunable characteristics of distributed feedback laser, a dual wavelength In photoacoustic spectrum measurement, optical chopper is commonly used to modulate frequency of light source output signal, however, the use of optical chopper inevitably leads to the increase of noise and cost of the system. On the basis of the tunable characteristics of distributed feedback laser, a dual wavelength modulation metod of the laser is proposed. Using photoacoustic spectroscopy experimental platform with optical chopper modulation laser system, we carry out the detection sensitivity experiment of methane. The results show that the detection sensitivity of optical chopper to methane is 52.3×10-6, and that of the dual wavelength modulation laser system to methane is 40.2×10-6. The dual wavelength modulation method avoids the use of optical chopper, decreases the system noise, and improves the system sensitivity..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111404 (2017)
Passively Mode-Locked Fiber Laser Based on Transmission/Reflection Composite Double Saturable Absorber
He Guanglong, Xu Li, Ma Xiaohui, Xu Chengyang, Zou Yonggang, Wu Guosheng, Sui Qingxue, Zhang Zhimin, and Jin Liang
This paper studies the problem of wide pulse pedestal and low pulse energy of a single semiconductor saturable absorber (SESAM) mode-locked fiber laser, and reports a type of transmission/reflection composite double saturable absorber (SA) passively mode-locked ultrashort pulse fiber laser based on a linear cavity struThis paper studies the problem of wide pulse pedestal and low pulse energy of a single semiconductor saturable absorber (SESAM) mode-locked fiber laser, and reports a type of transmission/reflection composite double saturable absorber (SA) passively mode-locked ultrashort pulse fiber laser based on a linear cavity structure. By increasing the transmission of SA, the times of the light pulse passing through the transmissive SA increases in the process of one oscillation cycle. The absorbance of the absorber on the front and back edge of the optical pulse is improved. The effect of the SESAM lower modulation depth on the pulse width and single pulse energy is eliminated. The influence of dispersion and nonlinearity caused by excessive pump power is reduced, and the single pulse energy is further improved. Finally, compared to the single reflection SESAM structure with the same modulation depths, the pulse width of the composite double SA mode-locked structure is shortened from 776 fs to 732 fs and the single pulse energy is increased from 2.08 nJ to 2.49 nJ..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111405 (2017)
Effect of Laser Peening on Fatigue Strength of TC17 Titanium Alloys
Huang Shuai, Zhu Ying, Guo Wei2, Peng Peng2, and Diao Xungang
In order to study the effect of laser peening (LP) on the fatigue strength of TC17 titanium alloys, the alloys are processed by LP for two times, and the fatigue strength of the materials before and after LP are tested and compared with the lifting and lowering method. The results show that the 11.7 μm deep micropits fIn order to study the effect of laser peening (LP) on the fatigue strength of TC17 titanium alloys, the alloys are processed by LP for two times, and the fatigue strength of the materials before and after LP are tested and compared with the lifting and lowering method. The results show that the 11.7 μm deep micropits form on the surface of TC17 titanium alloys after LP and the produced residual compressive stress is 2.46 times that before LP. The increase of the residual compressive stress leads to the location change of crack sources and the refinement of fatigue strips, and the fatigue strength of TC17 titanium alloys is increased by 3.9%..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111406 (2017)
Self-Correction Design for Thermal-Induced Wavefront-Distortion in Slab Laser Module
Liu Liang, Wang Shanshan, Huang Xiujun, Xu Hongyan, Song Zhenjiang, and Shi Dele
In order to solve the problem of poor output beam quality of slab lasers, we establish a thermal-induced wavefront-distortion model of the lasers transfer along zigzag in slab laser module. Distribution characteristics of thermal-induced wavefront-distortion are studied and a method for reducing thermal-induced wavefroIn order to solve the problem of poor output beam quality of slab lasers, we establish a thermal-induced wavefront-distortion model of the lasers transfer along zigzag in slab laser module. Distribution characteristics of thermal-induced wavefront-distortion are studied and a method for reducing thermal-induced wavefront-distortion is proposed. Numerical simulation results show that the position offsets of laser beam propagating through the slab medium twice at the same angle can be optimized to eliminate the thermal-induced wavefront-distortion in thickness direction of slab with the help of reasonable optical path design..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111407 (2017)
Effects of Laser Remelting and Nano SiC on Microstructure and Properties of Fe-Based Coating
Zhao Yuncai, and Zhang Jiwu
The plasma spraying Fe-based WC coating is treated by conventional laser remelting and laser remelting with addition of nano SiC. The surface morphology and cross-section morphology are observed by scanning electron microscopy, and the distribution of the elements at the interface of three coating are analyzed by energThe plasma spraying Fe-based WC coating is treated by conventional laser remelting and laser remelting with addition of nano SiC. The surface morphology and cross-section morphology are observed by scanning electron microscopy, and the distribution of the elements at the interface of three coating are analyzed by energy dispersive spectroscopy. The phase composition of the coatings are analyzed by X-ray diffractometer, the surface residual stress is calculated and the microhardness in different depths of the coatings is measured. The results show that pores, cracks, and other micro-defects in plasma spraying coating are improved under the action of laser melting and nano SiC, the content of CrSi2, Cr7C3, and other hard alloy phase increase, and new phases such as Fe2Si and CrSi generate. The surface residual stress reduces from 363.4 MPa to 158.6 MPa, and the microhardness increases from 631 HV to 1195 HV..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111408 (2017)
Temperature Field Simulation of Single-Layer Carbon Fiber Reinforced Plastics in Multi-Directional Laser Cutting
Yu Dongyang, and Wang Xuyue
The effects of carbon fiber orientation and resin content on the laser energy transfer direction and cutting quality during laser cutting of carbon fiber reinforced plastics (CFRP) are studied. According to the mixture rule of composites, the parameters are set, and the three dimensional finite element models for singlThe effects of carbon fiber orientation and resin content on the laser energy transfer direction and cutting quality during laser cutting of carbon fiber reinforced plastics (CFRP) are studied. According to the mixture rule of composites, the parameters are set, and the three dimensional finite element models for single-layer CFRP with carbon fiber orientations of 0°, 45°, and 90°, and resin contents of 30% to 50% are established. The numerical simulation results show that, during the multi-directional laser cutting of single-layer CFRP, the energy transfer direction is mainly dependent on the laser cutting direction, and the angle of transfer direction increases with the increase of fiber orientation angle. As for the steady cutting, the energy transfer is mainly along the fiber orientation direction. With the increase of the fiber orientation angle, the dip angle of kerfs increases as well, the width of burned carbon fibers on the surface does not essentially change, the temperature field becomes wider, and the maximum temperature decreases. When the single-layer CFRP with different resin contents are cut, the width of heat affected zone and the maximum temperature both have approximately linear relationships with the resin content. Compared with the experimental results, the average errors from numerical simulations for the burned zone width and the heat affected zone width on carbon fiber surface are 10.66% and 13.09%, respectively..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111409 (2017)
Three-Dimensional Visualization for Numerical Simulation Data of Laser Transmission
Li Wanyi, Wang Peng, Zhang Junwei, Geng Yuanchao, Su Jingqin, and Jing Feng
Large laser facility has many characteristics including complex structure, a large number of design and simulation models, and diversity of data. Design and simulation results are usually shown on different software platforms, and a unified integration platform for interactive data visualization is not formed. To solveLarge laser facility has many characteristics including complex structure, a large number of design and simulation models, and diversity of data. Design and simulation results are usually shown on different software platforms, and a unified integration platform for interactive data visualization is not formed. To solve these problems, we not only propose a three-dimensional (3D) visualization method for numerical simulation data of laser transmission based on 3D engine named Three.js and visualization library for numerical data named Vis.js, but also develop the corresponding software system. Firstly, the architecture of the 3D visualization system for numerical simulation data of laser transmission is presented. And then, the modules and key algorithms are designed and the implementation tools are given. Finally, the performance of the system is shown and summarized. The results show that the developed system can be used to visualize the designed transmission structure and simulation data of large laser facility. The visualization effect of optical path design of laser driver and transmitting simulation can be improved effectively..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111410 (2017)
Laser Cladding Reparation of Inner Cylinder Piston Rods
Zhai Jianhua, Liu Zhijie, Zhang Yong, Shi Yaojun, Deng Han, and Wei Xiaohua
With the laser cladding technology, two different types of alloy powders are chosen to repair the inner cylinder rod surface. The microstructures, microhardness, corrosion resistance and wear resistance of the cladding layers with two different types of powders are compared and analyzed. The suggestions are given in teWith the laser cladding technology, two different types of alloy powders are chosen to repair the inner cylinder rod surface. The microstructures, microhardness, corrosion resistance and wear resistance of the cladding layers with two different types of powders are compared and analyzed. The suggestions are given in terms of the applicative working environments of the inner cylinder piston rods repaired with these two different cladding materials. The study results show that these two types of cladding layer materials can both effectively improve the abrasive resistance, impact resistance and corrosion resistance performances of the inner cylinder piston rod surfaces..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111411 (2017)
Irradiation Effect of Continuous-Wave Laser on Triple-Junction GaAs Solar Cells
Zhou Guanglong, Xu Jianming, Lu Jian, Li Guangji, and Zhang Hongchao
In the air and the vacuum, triple-junction gallium arsenide (GaAs) solar cells are irradiated by the 1070 nm continuous-wave (CW) laser and the current-voltage curves of cells before and after laser irradiation are tested. By using the laser beam induced current (LBIC) measuring system and the X-ray photoelectron spectIn the air and the vacuum, triple-junction gallium arsenide (GaAs) solar cells are irradiated by the 1070 nm continuous-wave (CW) laser and the current-voltage curves of cells before and after laser irradiation are tested. By using the laser beam induced current (LBIC) measuring system and the X-ray photoelectron spectrometer (XPS), the damage situations of triple-junction GaAs solar cells are analyzed. The results show that, when the laser power density is 8.4 W/cm2 and the irradiation time is 10 s, the bottom-cell Ge is fused and short-circuited in the air, and the top-cell Ga0.5In0.5P and the bottom-cell Ge are both short-circuited in the vacuum, which means the bottom-cell of triple-junction GaAs solar cells is the most easily damaged part and the cell is easier to be destroyed in the vacuum than in the air. These study results can provide references for the research on laser wireless energy transmission and the laser damage mechanisms of triple-junction GaAs solar cells..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111412 (2017)
Directional Backlight Flattop Beam Obtained by Butterfly Liquid Crystal Switch for Autostereoscopic Display
Chen Fangping, Zhang Xiaoting, Zhuang Qiren, Liu Chujia, Qi Yu, and Wu Fengtie
We study the principle and method of obtaining cylindrical lens type directional backlight flattop beam by using a butterfly liquid crystal switch. Based on the generalized Huygens-Fresnel diffraction integral theory, we deduce the diffraction field distribution expression of beam after passing through cylindrical lensWe study the principle and method of obtaining cylindrical lens type directional backlight flattop beam by using a butterfly liquid crystal switch. Based on the generalized Huygens-Fresnel diffraction integral theory, we deduce the diffraction field distribution expression of beam after passing through cylindrical lens, and the butterfly liquid crystal switch unit is the light source of the beam. Placing the butterfly liquid crystal switch unit on the cube focal plane of the cylindrical lens, we simulate transverse optical field energy distribution curves at cylindrical lens with different focal lengths by MATLAB programming, and analyze the influence of butterfly parameter on the transverse optical field energy distribution. The results show that the energy uniformity of the transverse diffraction field energy firstly increases and then decreases with the reduction of the butterfly parameter, thus there exists a butterfly parameter that can maximize the energy uniformity..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111413 (2017)
Machine Vision
Automatic Inspection of Bolt Missing at the Bottom of Multiple Unit Trains Under Complex Environment
Lu Shengfang
The bolt at the bottom of multiple unit train plays a key role in the overall braking system of the train. The bolt missing will bring serious challenges for the train safety braking and safety running. By the example of fault inspection of bolt missing, an online inspection and recognition algorithm is proposed for thThe bolt at the bottom of multiple unit train plays a key role in the overall braking system of the train. The bolt missing will bring serious challenges for the train safety braking and safety running. By the example of fault inspection of bolt missing, an online inspection and recognition algorithm is proposed for the fault of components missing in a train, which provides a guidance for the targeted inspection on the key parts of the train. Due to the characteristics of the bolts geometry, a complete local binary patterns feature extraction algorithm based on the image Sobel gradient edge is proposed, and the training and learning of a binary classifier is combined to complete the automatic fault inspection of bolt missing. The results show that the proposed algorithm has strong robustness to inspect the fault in complex scenes with high inspection efficiency and precision, which can meet the demand of the site application..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111501 (2017)
An Improved Discrete-Continuous Energy Minimization for Multi-Target Tracking
Zhang Lijuan, and Zhou Zhiping
Aiming at the problems that the discrete-continuous energy minimization (DCEM) method cannot effectively deal with the trajectory segmentation and identity switch in complex scene, an improved DCEM multi-target tracking method is put forward. In order to solve identity switch, this method extracts the multi-feature fusAiming at the problems that the discrete-continuous energy minimization (DCEM) method cannot effectively deal with the trajectory segmentation and identity switch in complex scene, an improved DCEM multi-target tracking method is put forward. In order to solve identity switch, this method extracts the multi-feature fusion appearance vector of the tracked target, and uses the Euclidean distance between appearance vectors from different targets to design the constraint function for trajectories. Then this method designs the post-processing process for trajectory segmentation problem by merging the short tracklets which have high similarity of motion and appearance in adjacent spatial-temporal neighborhood. Experimental results indicate that the average tracking accuracy and average tracking precision can increase by 3.6% and 2.5%，respectively. Furthermore, the problems of trajectory segmentation and identity switch can be greatly improved. The proposed method has better robustness and the tracking accuracy..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111502 (2017)
Point Cloud Registration Algorithm Based on the ISS Feature Points Combined with Improved ICP Algorithm
Li Renzhong, Yang Man, Tian Yu, Liu Yangyang, and Zhang Huanhuan
Aiming at the problems of long reconstruction time，slow convergence and error matching corresponding points for the point cloud registration, a new algorithm based on the intrinsic shape signature (ISS) feature points combined with the improved iterative closest point (ICP) algorithm is proposed. Firstly, the feature pAiming at the problems of long reconstruction time，slow convergence and error matching corresponding points for the point cloud registration, a new algorithm based on the intrinsic shape signature (ISS) feature points combined with the improved iterative closest point (ICP) algorithm is proposed. Firstly, the feature points of point cloud are extracted by the ISS algorithm and described by the fast point feature histograms algorithm. Then, the initial registration of point cloud is completed by using the sample consensus initial alignment algorithm to make the two different angle point clouds obtain a relatively good initial position. Finally, the ICP registration efficiency is promoted by the k-dimension tree nearest neighbor search algorithm. The experimental results show that the proposed algorithm has higher registration accuracy and faster execution speed than the traditional registration algorithms..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111503 (2017)
Optimization of Camera Internal Parameters Based on Particle Swarm Algorithm
Guo Tongying, Li Ningning, and Liu Yong
Aiming at the problem that the calibration accuracy of MATLAB calibration toolbox is proportional to the number of images taken, which means the larger the number of photo frames, the higher the calibration accuracy. A method of internal parameter optimization based on particle swarm algorithm is proposed, and the bettAiming at the problem that the calibration accuracy of MATLAB calibration toolbox is proportional to the number of images taken, which means the larger the number of photo frames, the higher the calibration accuracy. A method of internal parameter optimization based on particle swarm algorithm is proposed, and the better effects can be achieved with few pictures. First the camera shoots 4 and 20 calibration plate pictures in different angles, and their internal parameters are obtained with the use of MATLAB calibration toolbox. The objective function is established through the calibration point of the actual coordinates and the back projection coordinates, and then the internal parameters obtained by calibration box are optimized by the particle swarm algorithm. The experimental results show that this method can improve the calibration accuracy of a small number of calibration plate pictures to a certain extent compared with the MATLAB calibration toolbox..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111504 (2017)
Materials
Effect of Porosity on Thermal Diffusivity of Woven Carbon Fiber Reinforced Polymers
Wu Enqi, Li Meihua, Gao Qian, and Mandelis Andreas
A four-layer photothermal radiometry model is proposed and the thermal diffusivity of woven carbon fiber reinforced polymers (CFRP) is researched. The experimental device is calibrated with the glass carbon as the reference material, and the detection tests of the fourteen groups of CFRP samples with porosities of 0 toA four-layer photothermal radiometry model is proposed and the thermal diffusivity of woven carbon fiber reinforced polymers (CFRP) is researched. The experimental device is calibrated with the glass carbon as the reference material, and the detection tests of the fourteen groups of CFRP samples with porosities of 0 to 18.32% are accomplished. The least-square objective function is constructed, the optimal solution is obtained by the genetic algorithm, and the thermal diffusivities of CFRP with different porosities are acquired. The results show that the thermal diffusivities of the fourteen group of CFRP samples are within the range of 3.01×10-7-8.73×10-7 m2·s-1, which decrease with the increase of porosity. When the porosity is smaller than 1.00%, the thermal diffusivity shows an obvious downtrend, while when the porosity is larger than 1.00%, the descent speed slows down..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111601 (2017)
Properties of GaAs0.9Sb0.1 Epilayer Grown by Two Growth Models of Liquid Phase Epitaxy Technique
Xie Hao, Hu Shuhong, Wang Yang, Huang Tiantian, Pan Xiaohang, Sun Yan, and Dai Ning
GaAs0.9Sb0.1 epilayer is grown by two growth models of liquid phase epitaxy technique, and the two models are step-cooling and super-cooling, respectively. The crystal structure, cross-sectional image, and luminescence property of GaAs0.9Sb0.1 epilayer are studied with utilization of X-ray diffractometer, scanning elecGaAs0.9Sb0.1 epilayer is grown by two growth models of liquid phase epitaxy technique, and the two models are step-cooling and super-cooling, respectively. The crystal structure, cross-sectional image, and luminescence property of GaAs0.9Sb0.1 epilayer are studied with utilization of X-ray diffractometer, scanning electron microscope, and Raman spectometer. The results show that the growth rate of GaAs0.9Sb0.1 epilayer grown with step-cooling is slower than that with super-cooling, and GaAs0.9Sb0.1 epilayer grown by step-cooling exhibits higher-quality crystalline structure and smoother interface. However, the GaAs0.9Sb0.1 epilayer grown by the two growth models display substantially similar photoluminescence property..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111602 (2017)
Band Gap of Triple Lattice Photonic Crystals with Dielectric Ring Shape
Liu Ziyan, Tang Jiyu, Liu Juan, Chen Yan, Dong Guiren, and He Youqing
One triple lattice photonic crystal with a dielectric ring shape is proposed and its complete band gap is studied. By using the Rsoft software, the influence rules of each parameter on the complete band gap are studied. On this basis, the dielectric ring shaped structure is optimized. The results show that, with the inOne triple lattice photonic crystal with a dielectric ring shape is proposed and its complete band gap is studied. By using the Rsoft software, the influence rules of each parameter on the complete band gap are studied. On this basis, the dielectric ring shaped structure is optimized. The results show that, with the increase of the dielectric constant of the dielectric ring, the complete band gap of the photonic crystal first increases and then decreases. With the increase of the ratio of inner diameter to outer diameter of the dielectric ring, the complete band gap first increases and then decreases. When the dielectric constant of the dielectric ring is 14.71 and the ratio of inner diameter to outer diameter is 0.42, the maximum complete band gap reaches 0.168..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111603 (2017)
Medical Optics and Biotechnology
Preliminary Exploration on Diagnosis of Laryngeal Carcinoma Based on Raman Spectroscopy
Kang Jing, Luo Shi, He Jian, Wu Ping, Xu Jing, Fang Xing, Wang Yunyun, Zhang Shuai, and Tang Yaoyun
To compare laryngeal carcinoma tissues and pericarcinous tissues in Raman spectrogram to obtain their respective features and patterns, we establish a diagnose model for laryngeal carcinoma. A total of 110 samples including 54 laryngeal carcinoma samples and 56 pericarcinous samples are acquired from patients undergoinTo compare laryngeal carcinoma tissues and pericarcinous tissues in Raman spectrogram to obtain their respective features and patterns, we establish a diagnose model for laryngeal carcinoma. A total of 110 samples including 54 laryngeal carcinoma samples and 56 pericarcinous samples are acquired from patients undergoing laryngectomy from October 2014 to August 2015 in otolaryngology, head & neck surgery of Xiangya hospital of central south university. All of the samples are processed by the accordant method before Roman spectrum detection. Original data are collected for pretreatment and statistical analysis. The results show that the average Roman spectrum intensity of the laryngeal carcinoma tissues is greater than that of the pericarcinous tissues, and the laryngeal carcinoma tissues have stable Roman peak groups. Statistical difference of the two groups of samples are verified through student′s t-test in bands with wave numbers of 150-1859 cm-1, 1864-1872cm-1, 1890-1898.5 cm-1, 1900-1924 cm-1, 1964-1968 cm-1, 1993-1998.5 cm-1, and 2010.5-3476 cm-1(significance level p＜0.05). Three principal components are extracted with the help of analysis of the significant wave numbers using principal components analysis-linear discriminant analysis (PCA-LDA). Using them as inputs of LDA, we calculate discriminant function coefficient and establish a discriminant model. The discriminant model has better specificity of 80.4% and sensitivity of 87.0% for sample prediction. The laryngeal carcinoma diagnose model is evaluated by received operator characteristic (ROC) curve method, and the value of area under the curve (AUC) is 0.877. There are remarkable and stable differences between the laryngeal carcinoma tissues and the pericarcinous tissues. The discriminant model established by the method of multivariate statistical analysis has better reliability. This study demonstrates that Raman spectroscopy has the potential for the noninvasive, real-time diagnosis and detection of laryngeal carcinoma at the molecular level..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111701 (2017)
Nonlinear Optics
Evolution of Quadrupole Solitons in Self-Focusing Photoinduction Tetragonal Photonic Lattices
Qin Yali, Mao Shengyi, Liu Xian, Li Yilei, Ren Hongliang, Li Jia, and Xue Linlin
Out-of-phase (OOP) and in-phase (IP) quadrupole beams propagation in self-focusing photoinduction tetragonal photonic lattices is investigated by alternative direction implicit-beam propagation method (ADI-BPM). The evolution of OOP and IP quadrupole beams in continuous homogeneous medium, self-focusing medium and selfOut-of-phase (OOP) and in-phase (IP) quadrupole beams propagation in self-focusing photoinduction tetragonal photonic lattices is investigated by alternative direction implicit-beam propagation method (ADI-BPM). The evolution of OOP and IP quadrupole beams in continuous homogeneous medium, self-focusing medium and self-focusing photoinduction photonic lattices is presented respectively. In the continuous homogeneous medium, it is shown that OOP quadrupole beams are linearly diffracted, with the peak intensity decreasing gradually. Besides, the beams repel each other and the peak spacing becomes larger. IP quadrupole beams are diffracted originally, and then fused into the single beam. The peak is decreased in the beginning and then increased. As the beam is transmitted forward and diffracted, the peak intensity declines. In the self-focusing nonlinear medium, the OOP quadrupole beams could self-focus and the separation becomes more obvious, while the IP quadrupole beams could attract each other and merge into a single beam. In the self-focusing light photoinduction lattices, under appropriate conditions, the OOP quadrupole beams could form the stable OOP quadrupole solitons whose diagonal humps have the same phase but the adjacent humps have π-phase difference, while the IP quadrupole beams could form the localized IP quadrupole solitons whose four humps have the same phase..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 111901 (2017)
Optical Design and Fabrication
Contour Line Optimization Design of Progressive Addition Lenses Based on Laplace Equation
Zhang Hao, Tang Yunhai, Wu Quanying, and Chen Xiaoyi
The contour u of the progressive addition lens (PAL) surface is designed to obtain a PAL whose near visual area is obviously expanded and the progressive channel length is decreased. The PAL is designed symmetrically. The curve of u at meridian line is set as the boundary conditions of the Laplace equation, and the speThe contour u of the progressive addition lens (PAL) surface is designed to obtain a PAL whose near visual area is obviously expanded and the progressive channel length is decreased. The PAL is designed symmetrically. The curve of u at meridian line is set as the boundary conditions of the Laplace equation, and the specific form of the boundary conditions is given. Combined with the natural boundary condition, the analytic solution of the Laplace equation is solved using the separation of variables method and the Fourier transform method. The design example shows that this design method not only expands the wide range of near zone visible area of PAL, but also shortens the progressive channel length. The design data are processed actually, and the PAL obtained is tested and analyzed. The results show that the design and the actual test results are basically consistent..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 112201 (2017)
Design and Simulation of Large Angle Lens for Ultra-Thin Direct-Down LED Panel Light
Li Jianpeng, Guo Zhenning, Lin Jieben, Zhang Jianing, Yang Yulong, Xue Dongdong, Chen Zhonghang, and Huang Xueling
Based on the law of conservation of energy and the mesh generation method, a lens with large view angle for ultra-thin direct-down LED panel light is proposed. The illumination distribution of the target plane of the Lambertian type LED at a height of 96 mm is used as the desired illumination distribution to optimize tBased on the law of conservation of energy and the mesh generation method, a lens with large view angle for ultra-thin direct-down LED panel light is proposed. The illumination distribution of the target plane of the Lambertian type LED at a height of 96 mm is used as the desired illumination distribution to optimize the feedback of the large angle LED lens, and form a light field with a desired illumination distribution on a target plane with a height of 25 mm. To investigate the influence of the large angle LED lens after optimization on the thickness reduction degree of the straight down LED flat lamp, the height of the target surface is set to be 20, 25, 30 mm respectively, and then the spacing of the square LED arrays is set to be 96, 82, 75 mm respectively. The software LightTools is used to simulate and analyze the uniformity of the target illumination of the direct LED flat lamp. The results show that when the target plane height is 25 mm and the pitch of the square LED array is 82 mm, the illumination uniformity of the target plane is the best. And the value (the minimum illumination is divided by the maximum illuminance) is 0.8756, which meets the national technical requirements for the application of LED indoor lighting..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 112203 (2017)
Freeform Surface Combination Design Method of Multidirectional Parallel Beam Splitting Lens
Lin Haobo, Wan Yunjia, Liu Jie, Zhang Jian, and Xiong Hui
A combination design method of freeform surface of multidirectional parallel beam splitting lens is proposed, which can be applied to the light emitting diode (LED) light source of generalized Lambertian distribution to realize any multidirectional parallel beam splitting. A lens is designed for the rainfall sensor, whA combination design method of freeform surface of multidirectional parallel beam splitting lens is proposed, which can be applied to the light emitting diode (LED) light source of generalized Lambertian distribution to realize any multidirectional parallel beam splitting. A lens is designed for the rainfall sensor, which can increase the number of outgoing ray paths without adding the light source. The designed lens has such advantages as small volume and high luminous efficiency, which can help to increase the optical detection of the sensor area and provide convenience to the design and optimization of related photoelectricity devices. Theoretical calculation and modeling simulation further verify the feasibility and validity of this plan..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 112204 (2017)
Design of Optical System for Large Magnification Interference Microscope Objective
Meng Han, Wan Xinjun, Dong Yifan, Xie Shuping, and Bin Boyi
Interference microscope objective is a key component of interferometric microscopy, which is widely used in the measurement of three-dimensional topography of micro-nano-surface. In this paper, an infinite conjugate large magnification Mirau interference microscope objective is designed, with the magnification ratio ofInterference microscope objective is a key component of interferometric microscopy, which is widely used in the measurement of three-dimensional topography of micro-nano-surface. In this paper, an infinite conjugate large magnification Mirau interference microscope objective is designed, with the magnification ratio of up to 50× and the numerical aperture of 0.5. Based on the characteristics of the long working distance of the system, the interference objective lens adopts the retrofocus objective structure. According to the second-order spectral theory, the secondary spectral aberration correction of the interference objective is analyzed, and the glass materials and lens initial structure are selected rationally. The optical system is optimized by utilizing the optical design software Code-V. The design results show that the modulation transfer function at 800 lp/mm is more than 0.3 in the whole field of view of the optical system, and other indexes all meet the design requirements. By non-sequential modeling, optical tracing of the designed interference objective is carried out, the clear Newton ring interferogram is obtained by simulation and analysis. Which proves the rationality of the design..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 112205 (2017)
Optical Devices
Test System for Power Generation Characteristics of Photovoltaic Modules Based on Real-Time Parameters
Cai Li, Dai Nina, Zhu Haitao, Tan Zefu, and Qiu Gang
The power generation characteristics of photovoltaic modules are of great significance to optimize the power generation efficiency of photovoltaic power generation system. The generation characteristics of photovoltaic module are commonly obtained from theoretical simulation, which are different from the characteristicThe power generation characteristics of photovoltaic modules are of great significance to optimize the power generation efficiency of photovoltaic power generation system. The generation characteristics of photovoltaic module are commonly obtained from theoretical simulation, which are different from the characteristics obtained from practical application. The calculation model of photovoltaic module power generation characteristics is established by using lighting sensors and temperature sensors to collect environmental parameters, galvanometer and voltmeter to detect parameters such as photo-generated current, reverse cutoff current, open circuit voltage and so on. Accurate testing of power generation characteristics of photovoltaic modules is achieved. The power generation characteristic curves of output voltage-output current and output power-output voltage under different environmental parameters are got. The simulation and engineering tests show that the photovoltaic power generation system based on the above characteristic curve can achieve better performance when controlling the maximum power, and the error between theoretical value and practical value is less than 1%..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 112301 (2017)
Optics at Surfaces
Propagation Characteristics of Dielectric-Loaded Graphene Plasma Waveguides
Wang Qingchen, and Song Liang
A dielectric-loaded graphene plasma waveguide is proposed and the mode field distributions and propagation characteristics of the waveguides with different sizes are studied. The simulation results show that, when the chemical potential of graphene is 0.7 eV, and the ridge width and the ridge height are both 1000 nm, tA dielectric-loaded graphene plasma waveguide is proposed and the mode field distributions and propagation characteristics of the waveguides with different sizes are studied. The simulation results show that, when the chemical potential of graphene is 0.7 eV, and the ridge width and the ridge height are both 1000 nm, the mode width of dielectric-loaded graphene plasma waveguide reaches the minimum value of 1.55 μm and the propagation length reaches 43.47 mm. This dielectric-loaded graphene plasma waveguide not only can meet the requirement of waveguide design, but also provides a possibility of long-distance transmission for nano-devices..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 112401 (2017)
Physical Optics
Optical Absorption Property of Graphene PN Junction Modulated by Voltage in Terahertz Region
Yang Cuihong, Wang Lu, Chen Yunyun, and Lei Yong
Based on the method to constitute a PN junction with the addition of external positive and negative voltages at both ends of graphene sheets, the relationships among the optical conductivity and optical absorption with the external voltage, disorder broadening width, and temperature are studied by adjusting the gate anBased on the method to constitute a PN junction with the addition of external positive and negative voltages at both ends of graphene sheets, the relationships among the optical conductivity and optical absorption with the external voltage, disorder broadening width, and temperature are studied by adjusting the gate and bias voltages. The study results show that the optical conductivity of graphene has negative value in the terahertz region and the light transmissivity increases. In the terahertz region, the optical conductivity depends on the external bias voltage and the disorder broadening width monotonously, but on the temperature complicatedly. Under a given applied voltage, the optical transmissivity can be enhanced if an appropriate temperature is chosen. The study results provide theoretical references for the applications of graphene in the terahertz region..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 112601 (2017)
Remote Sensing and Sensors
Automatic Extraction Algorithm of Seismic Landslide Information Based on After-Calamity High-Resolution Remote Sensing Image
Yan Qi, Li Hui, Jing Linhai, Tang Yunwei, and Ding Haifeng
Aiming at the high efficiency requirement of extraction seismic landslide, we propose an automatic extraction algorithm of seismic landslide based on after-calamity high-resolution remote sensing image. The algorithm utilizes the spectrum, shape, and texture features of seismic landslide of the remote sensing image to Aiming at the high efficiency requirement of extraction seismic landslide, we propose an automatic extraction algorithm of seismic landslide based on after-calamity high-resolution remote sensing image. The algorithm utilizes the spectrum, shape, and texture features of seismic landslide of the remote sensing image to remove the disturbed features based on the analytic hierarchy process, and realizes the automatic extraction of the seismic landslide. All the feature parameters are computed automatically by the improved Otsu algorithm. In a test using high-resolution aerial remote sensing data acquired by ADS40 image after earthquake Wenchuan in 2008, the experiments demonstrate that more than 70% landslides are correctly detected by the proposed method. Furthermore, the area accuracy is more than 80% and the extraction time is less than one minute for the ADS40 image with 10000 rows and 10000 columns data. Compared with traditional visual interpretation of human-computer interaction, the proposed algorithm has high degree of automation and landslide extraction speed, and the landslide recognition accuracy can meet the earthquake disaster emergency requirements..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 112801 (2017)
Laser Intensity Correction of Terrestrial 3D Laser Scanning Based on Sectional Polynomial Model
Cheng Xiaolong, Cheng Xiaojun, Li Quan, and Xu Wenbing
The laser intensity of same targets may vary significantly due to the influence of laser measuring distance between scanner and object, laser incidence angle, and atmospheric conditions, etc. The distance effect and incidence angle effect are corrected based on the laser radar range equation. The laser intensity is linThe laser intensity of same targets may vary significantly due to the influence of laser measuring distance between scanner and object, laser incidence angle, and atmospheric conditions, etc. The distance effect and incidence angle effect are corrected based on the laser radar range equation. The laser intensity is linearly proportional to the cosine of the incidence angle. However, the distance effect of laser intensity is more complicated, and the laser intensity is not inversely proportional to the square of the distance. Therefore, the sectional polynomial model is proposed to correct the distance effect. The experimental results indicate that the proposed model can effectively compensate the point cloud laser intensity. The deviation of intensity caused by the distance and incidence angle can be removed effectively with angle correction and distance correction, which makes the corrected laser intensity of the same target tend to be consistent..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 112802 (2017)
Reviews
Recent Progress of High-Power Cladding Light Stripper
Sun Jing, Zou Shuzhen, Chen Han, Yu Haijuan, Wang Xubao, and Lin Xuechun
The cladding light stripper (CLS) is a key device to guarantee the stability and beam quality of high-power all fiber lasers. It is an especially important step to effectively strip the cladding light for all fiber lasers and its engineering. We present a detailed discussion about the latest progress of the fabricationThe cladding light stripper (CLS) is a key device to guarantee the stability and beam quality of high-power all fiber lasers. It is an especially important step to effectively strip the cladding light for all fiber lasers and its engineering. We present a detailed discussion about the latest progress of the fabrication technology of CLS, which is classified three types based on refraction effect, absorption effect and scattering effect. The characteristics of various techniques to manufacture CLS are analyzed. Some suggestions are put forward to achieve high power cladding light strippers with low temperature rise coefficient and high attenuation coefficient in the future..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 110001 (2017)
Noise-Like Pulsed Fiber Lasers
Chen Jiawang, and Zhao Luming
Noise-like pulses (NLP) are a kind of special pulse with high energy, wide spectral bandwidth, and low coherence, which are generated from the passively mode-locked fiber lasers under certain conditions. In recent years, NLP fiber lasers have developed rapidly because of the fast development of doping technology, mode-Noise-like pulses (NLP) are a kind of special pulse with high energy, wide spectral bandwidth, and low coherence, which are generated from the passively mode-locked fiber lasers under certain conditions. In recent years, NLP fiber lasers have developed rapidly because of the fast development of doping technology, mode-locking technology, fiber amplification technology, and the improvement of pump energy. Based on this, NLP fiber lasers with different mode locking techniques operated in different dispersion regimes were summarized. The NLP fiber lasers were classified based on the discrepancy in its pulse generation mechanism and optical properties. Research status and progress of the fiber lasers at home and abroad was reviewed. Finally, the application of the fiber lasers in production practice was briefly depicted..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 110002 (2017)
Research Progress on Quantum Dot Light Emitting Diodes
Chen Wenbai, Ma Hang, Ye Jixing, and Li Denghua
Quantum dot materials have extremely high application value in the fields of displays and solid-state lighting due to their unique light emission characteristics. Compared with the traditional display devices, quantum dot light emitting diodes (QLEDs) have the advantages of high stability, good solution processability Quantum dot materials have extremely high application value in the fields of displays and solid-state lighting due to their unique light emission characteristics. Compared with the traditional display devices, quantum dot light emitting diodes (QLEDs) have the advantages of high stability, good solution processability and high color saturability, which make them become the core device of the new generation display technology. The structure, working principle and research progresses of QLEDs are introduced, and their application status and prospects in China display industry are also presented..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 110003 (2017)
Spectroscopy
Cementation Force of Compound Soil Mixed by Soft Rock and Sand:Raman Spectrum Study
Guo Hang, Han Jichang, Zhang Yang, Wang Huanyuan, Sun Yingying, Li Xiucheng, and Zhang Haiou
To study cementation force of compound soil mixed by soft rock and sand in Mu Us sand land in northern Shaanxi, we mix the soft rock and sand in different proportions to prepare compound soil, and then test the Raman spectra of the compound soil. According to the peak position of SiO2 at Raman shift 464 cm-1 varying wiTo study cementation force of compound soil mixed by soft rock and sand in Mu Us sand land in northern Shaanxi, we mix the soft rock and sand in different proportions to prepare compound soil, and then test the Raman spectra of the compound soil. According to the peak position of SiO2 at Raman shift 464 cm-1 varying with contents of the soft rock in the compound soil, we study the change of the cementation force of the compound soil particles. The results show that the peak position of the sand is 464.5 cm-1. With the increase of the content of the soft rock in the compound soil, the peak position decreases. This is because that the addition of the soft rock causes small particles in the soft rock to replace the position of large particles in the sand, the distance between soil particles increases, and the tensile stress appears due to tow between particles, which leads to the red shift of the Raman characteristic peak. When the volume ratio of soft rock to sand is 1∶1, the peak position decreases to 463.6 cm-1. When the volume ratio of soft rock to sand is 7∶5, the soil structure collapses and becomes firm, which results in the generation of compressive stress between particles. The compressive stress results in sudden increase of the peak position to 464.2 cm-1. Then the soil structure becomes stable. With the further increase of the soft rock content, there is still the replacement of samll particles of soft rock to large particles of sand, the tensile stress is obvious gradually, and the peak position constantly decreases to 463.1 cm-1 when the compound soil is sand. It is proved that the shifting of the peak position of SiO2 in Raman spectra can be applied to the study of cementation force between particles in compound soil..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 113001 (2017)
Thin Films
Reproducibility of Thin Films Deposited on Microstructure Surface by PECVD Technology
Pan Yongqiang, and Chen Jia
The thin films of SiO2 and Si3N4 are deposited on the microstructure surface of a linear array mask by the techniques of photolithography, etching and plasma enhanced chemical vapor deposition (PECVD). The influences of the width and thickness of the linear array mask, as well as the film thickness and deposition rate The thin films of SiO2 and Si3N4 are deposited on the microstructure surface of a linear array mask by the techniques of photolithography, etching and plasma enhanced chemical vapor deposition (PECVD). The influences of the width and thickness of the linear array mask, as well as the film thickness and deposition rate on the reproducibility of SiO2 and Si3N4 films are investigated. A microstructure filter array with a good microstructure is prepared. The results show that the larger the film deposition rate is, the better the film reproducibility is. The increases of mask thickness and film deposition thickness lead to the deterioration of thin film reproducibility. The reproducibility of SiO2 films is better than that of Si3N4 films..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 113102 (2017)
Effect of Film Micro-Structure of Tungsten Oxide Films Deposited by Magnetron Sputtering on Electrochromic Performance
Chu Wenjing, Zhang Xiqiang, Shi Xiayu, Zheng Youwei, Lin Junliang, Chen Mingyi, Lin Jinxi, Lin Jinhan, and Yuan Ningyi
By the magnetron sputtering method, the tungsten oxide (WO3) films are prepared under different working pressures. The regulating effect of working pressure on WO3 film microstructure is studied, and the effect of WO3 film microstructure on its electrochromic performance is also investigated. The study results show thaBy the magnetron sputtering method, the tungsten oxide (WO3) films are prepared under different working pressures. The regulating effect of working pressure on WO3 film microstructure is studied, and the effect of WO3 film microstructure on its electrochromic performance is also investigated. The study results show that the prepared WO3 film is with an amorphous phase and its surface presents a peak-shaped structure. With the increase of working pressure, the WO3 film microstructure becomes loose, and the electrochromic response time and the cycle lifetime are shorten. Under the optimal film microstructure condition, the optical density of WO3 films is 0.64 and the cycle lifetime is up to 1500 cycles..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 113103 (2017)
Performance Comparison of TiAlC Films Prepared with Different Precursors
Yang Yongliang, Li Na, and Zhang Hongyun
With the Al(CH3)3 as the precursor of Al elements, two kinds of TiAlC films are prepared by using the atomic layer deposition technique with the TiCl4 and the tetrakis (dimethylamino) titanium (TDMAT) as precursors of titanium elements, respectively, and their film performances are compared and analyzed. The results shWith the Al(CH3)3 as the precursor of Al elements, two kinds of TiAlC films are prepared by using the atomic layer deposition technique with the TiCl4 and the tetrakis (dimethylamino) titanium (TDMAT) as precursors of titanium elements, respectively, and their film performances are compared and analyzed. The results show that, both these two kinds of TiAlC films are oxidized naturally with different degrees. The optical band gap of films prepared with the TDMAT as precursor has two value of 0.68 eV and 2.00 eV, respectively, while that of the thin films prepared with the TiCl4 as precursor is 0.61 eV. Moreover, the average transmissivity, deposition rate, resistivity, and surface roughness of the former are all higher than those of the latter, while the thickness uniformity of the former is worse than that of the latter. The thin films prepared with the TiCl4 as precursor show an amorphous structure, while in the thin films prepared with the TDMAT as precursor, the TiN crystal appears. Compared with the organic compound TDMAT, the inorganic compound TiCl4 is more suitable as the precursor to prepare TiAlC gate dielectric materials..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 54, Issue 11, 113104 (2017)
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