Journals >Laser & Optoelectronics Progress
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2016
Volume: 53 Issue 4
36 Article(s)
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Atmospheric Optics and Oceanic Optics
Study on Polarized Light Scattering by Aerosol over Ocean
Sun Xianming, Wang Haihua, Shen Jin, and Wan Long
Based on the radiative transfer theory, the polarized light scattering characteristics of sea spray in an atmosphere-ocean system by sunlight is studied based on the matrix operator method. The whole atmosphere layer is divided into many sub-layers in the vertical direction, and the vertical distributions of the atmospBased on the radiative transfer theory, the polarized light scattering characteristics of sea spray in an atmosphere-ocean system by sunlight is studied based on the matrix operator method. The whole atmosphere layer is divided into many sub-layers in the vertical direction, and the vertical distributions of the atmosphere molecular, clouds and aerosol are considered. The ocean surface is dealt as the wind-generated rough ocean surface, and the wave slope distribution and the shadowing effect of the ocean wave are considered. The ocean body is divided into many plane parallel sub-layers, and the absorption and scattering characteristics of sea water and the chlorophyll are considered by an empirical model. The reflection and transmission matrices and source vectors are obtained for each atmospheric or oceanic layer though the discrete ordinate solution. The scattering characteristics of the whole atmosphere- ocean system are constructed using the matrix operated method, which combines the radiative interaction between the layers. The sensitivity studies for the reflected solar radiation by the whole atmosphere-ocean system are conducted for various solar wavelength, incidence solar zenith angle, observation angle, ocean-surface wind speed, the optical thickness of the clouds and aerosols, and the absorption of the gas. The simulation results show that the multi- wavelength and multi- angular polarization information are sensitive to the varies of the atmosphere and ocean surface conditions. The reflected solar radiative intensity and the polarization degree can be combined to retrieve the aerosol information..
Laser & Optoelectronics Progress
- Publication Date: Mar. 28, 2016
- Vol. 53, Issue 4, 40101 (2016)
Detectors
Target Detection Algorithm Based on Improved Single Gaussian Background Model
Xu Hongwei, Chen Qian, and Qian Weixian
In order to solve the problem that background model can not be well adapt to background changes in traditional single-Gaussian background model (SGM) detection, an innovative single-Gaussian background model detection method is proposed. N frames are used to establish the initial model, and the background area is obtaiIn order to solve the problem that background model can not be well adapt to background changes in traditional single-Gaussian background model (SGM) detection, an innovative single-Gaussian background model detection method is proposed. N frames are used to establish the initial model, and the background area is obtained by frame difference method. At the same time, the background is divided into a large area of the stationary area, historic changing area and historic area of the changing one. Then the large stationary area and historic changing area are taken with fixed update rate and the relevant track area of historic changing area is taken with linear attenuation in accordance with the time distribution. So background model parameters are updated. The moving target is obtained by using the background subtraction. According to the experiment, the self-adaptability of the proposed algorithm model is improved greatly, and the detection of moving target is more accurate based on single Gaussian background model..
Laser & Optoelectronics Progress
- Publication Date: Mar. 06, 2016
- Vol. 53, Issue 4, 40401 (2016)
Research on Nonlinear Distortion Effect in the Space Scanning Optical Fiber Fabry-Perot Sensor Demodulation System
Cao Xiao, Wang Shuang, Liu Kun, Liu Tiegen, Zou Shengliang, and Shi Junfeng
For the space scanning optical fiber Fabry- Perot (F- P) sensor demodulation system, the nonlinear distortion of CCD and its influence on absolute phase demodulation are investigated. The CCD response characteristic is measured and a fitting model is built. Then, the influence of nonlinear distortion under different stFor the space scanning optical fiber Fabry- Perot (F- P) sensor demodulation system, the nonlinear distortion of CCD and its influence on absolute phase demodulation are investigated. The CCD response characteristic is measured and a fitting model is built. Then, the influence of nonlinear distortion under different standard deviation of noise is simulated. The simulation results show that the standard deviation of the demodulated absolute phase increases with the increase of the nonlinear distortion rate. Meanwhile, interference order jump error resulting from the nonlinear distortion rate decreases with the increase of noise. The influence of nonlinear distortion is studied based on the optical fiber F-P pressure sensor demodulation system. The experimental results show that the nonlinear distortion rate under a fixed pressure increases with the optical power, and the interference order jump error appears when the nonlinear distortion rate is larger than 26.3%, which agrees with the simulation results. In addition, the demodulation accuracy decreases with the increase of the nonlinear distortion rate when the nonlinear distortion rate of fiber F-P full pressure sensing demodulation ranges from 0.3% to 22.3%. The demodulation error is 0.215 kPa when the nonlinear distortion rate is 22.3% , which has increased by 1.24 times as compared with that when the nonlinear distortion rate is 0.3%. In order to ensure the demodulation accuracy better than 0.04% in full scale, the nonlinear distortion rate should be controlled less than 6.7%..
Laser & Optoelectronics Progress
- Publication Date: Mar. 29, 2016
- Vol. 53, Issue 4, 40402 (2016)
Fiber Optics and Optical Communications
Polarization-Insensitive Phase Modulation in Fiber Quantum Key Distribution System
Li Ruixue, Ma Haiqiang, Wei Kejin, Zhu Wu, and Liu Hongwei
It introduces a simple and robust polarization-insensitive phase modulation method that is suitable for a plug and play quantum key distribution system, with a Faraday mirror and polarization sensitive phase modulator. The pulse is modulated twice acorrding to its polarization before and after it is reflected by a FaraIt introduces a simple and robust polarization-insensitive phase modulation method that is suitable for a plug and play quantum key distribution system, with a Faraday mirror and polarization sensitive phase modulator. The pulse is modulated twice acorrding to its polarization before and after it is reflected by a Faraday mirror. Preliminary experiments at 1550 nm wavelength demonstrate an interference visibility as high as 96%, regardless of the polarization of the signal..
Laser & Optoelectronics Progress
- Publication Date: Mar. 17, 2016
- Vol. 53, Issue 4, 40601 (2016)
Pulse-Repetition Rate Multiplication Based on Micro-Ring Resonator
Dong Xiaowei, Liu Manman, and Liu Wenkai
Transmission spectrum of series-coupled micro-ring resonator is analysed with transfer matrix method. It shows that the micro-ring resonator has comb filtering properties. When a pulse train goes through the micro-ring resonator, the frequency of input pulse train is choosed by the comb transmission spectrum of the micTransmission spectrum of series-coupled micro-ring resonator is analysed with transfer matrix method. It shows that the micro-ring resonator has comb filtering properties. When a pulse train goes through the micro-ring resonator, the frequency of input pulse train is choosed by the comb transmission spectrum of the micro- ring resonator, with the output pulse repetition rate multiplied and the period decreased after inverse Fourier transform. The results demonstrate that the amplitude of output pulse train by a double-ring resonator with equal radius is more uniform and the pulse-repetition rate multiplication (PRRM) effect is much better than by a single-ring resonator with the increase of multiplied pulse-repetition rate. Because series-coupled double-ring resonator with different radii can expand the free spectral range (FSR) and reduce the bending loss of the micro-ring resonator, high frequency and low loss of output pulse train can be obtained when it is used to achieve PRRM. The envelope of output pusle train presents triangle by optimizing the coupling coefficient of the micro-ring resonator, which can greatly improve its practicability..
Laser & Optoelectronics Progress
- Publication Date: Feb. 26, 2016
- Vol. 53, Issue 4, 40602 (2016)
Effects of Link Delay Fluctuations on Stability of Fiber-Optic Time Transfer
Jiang Shaoping, Zhang Hao, Jiang Wenning, Wu Guiling, and Chen Jianping
The delay fluctuations of optical fiber link, related to the variations of laser output wavelength and ambient temperature along the transmission link, directly affect the stability of fiber-optic time transfer. The relationship between the stability of long distance fiber- optic time transfer and the variations of lasThe delay fluctuations of optical fiber link, related to the variations of laser output wavelength and ambient temperature along the transmission link, directly affect the stability of fiber-optic time transfer. The relationship between the stability of long distance fiber- optic time transfer and the variations of laser wavelength and the temperature of optical fiber link is derived by using a link segmentation processing method. Wavelength fluctuations are modeled based on the analysis of measured wavelength data of laser. A 3000 km optical fiber link is emulated based on the actual temperature data, and the effects of wavelength fluctuations and depth of buried optical fiber link on the stability of fiber- optic time transfer adopting bidirectional time division multiplexing (BTDM) and wavelength division multiplexing (WDM) respectively are analyzed. The results show that the temperature variations of optical fiber link mainly have effect on the long-term stability, and this effect changes with the depth of buried optical fiber link and work season of time transfer. The wavelength jitter of laser mainly degrades the short-term stability of fiber-optic time transfer, while the wavelength drift of laser mainly has impact on the stability at the averaging time related to the cycle of wavelength drift. When the standard deviation of wavelength jitter of laser changes from (0.07, 0.05) pm to (0.27, 0.25) pm, the stability of 3000 km fiber-optic time transfer will deteriorate from 3 ps/s to 12 ps/s..
Laser & Optoelectronics Progress
- Publication Date: Mar. 12, 2016
- Vol. 53, Issue 4, 40603 (2016)
Young′s Modulus Measurement of Metal Beams Based on Fiber Bragg Grating
Quan Wenwen, Kang Juan, Yang Li, and Hu Junhui
A novel technique for measuring Young′s modulus of metal beams based on fiber Bragg gratings (FGBs) and three-point bend test is proposed. The FBG is sticked on the target metal beam and the three-point bend test method is used to load the force on the sheet. A universal formula for measuring Young′s modulus of variousA novel technique for measuring Young′s modulus of metal beams based on fiber Bragg gratings (FGBs) and three-point bend test is proposed. The FBG is sticked on the target metal beam and the three-point bend test method is used to load the force on the sheet. A universal formula for measuring Young′s modulus of various sheetshaped solid materials is derived, which is used for the experimental measurement of the Young′s modulus of iron and copper sheets. Experimental results show that the measurement errors of the two metal beams are 0.5% and 0.6% comparing to the nominal Young′s modulus, and the relationship between the reflected central wavelength and the loaded force is a good linearity. Moreover, the stick location of FBG has a negligible impact on the measurement precision. The proposed method has a potential application prospect in the field of Young′s modulus measurement of solid materials..
Laser & Optoelectronics Progress
- Publication Date: Mar. 11, 2016
- Vol. 53, Issue 4, 40604 (2016)
Image Processing
Detection of Red Region of Fuji Apple Based on RGB Color Model
Huang Zhaoliang, and Zhu Qibing
Color of fruits is an important index for the classification of fruits, which will affect consumers′ purchase desire. An algorithm based on RGB color model is studied to detect the red area of Fuji apple. The light compensation of image is used to reduce the effect of illumination change and nonuniformity of light sourColor of fruits is an important index for the classification of fruits, which will affect consumers′ purchase desire. An algorithm based on RGB color model is studied to detect the red area of Fuji apple. The light compensation of image is used to reduce the effect of illumination change and nonuniformity of light source. Two parameters of R/G and G/B in RGB image are calculated, and the thresholds of these two parameters are obtained by using training samples to achieve accurate segmentation for apple and background. The excess red minus excess green threshold segmentation method is applied to detect and calculate the red region of apple surface. The experimental results show that the algorithm based on RGB color model is able to accurately detect the red area of the apple surface. The algorithm can meet the requirement of color grading detection of Fuji apples..
Laser & Optoelectronics Progress
- Publication Date: Jan. 13, 2016
- Vol. 53, Issue 4, 41001 (2016)
Optical Interference Double Gray Image Encryption System Based on Compressive Sensing
Bai Yinbuhe, Lü Xiaodong, Li Genquan, and Qin Yi
A novel double gray image encryption method is proposed based on compressive sensing (CS) and interference principle. The 50% image data of two gray images are random extracted by the proposed method, these data are combined to form a synthetic image (SI), and then it is hidden into three phase only masks (POMs). One oA novel double gray image encryption method is proposed based on compressive sensing (CS) and interference principle. The 50% image data of two gray images are random extracted by the proposed method, these data are combined to form a synthetic image (SI), and then it is hidden into three phase only masks (POMs). One of the phase masks is produced by random function and the other two are obtained by analytic method. For decryption, the diffraction fields of the three POMs are superposed by employing the beam splitters. The intensity of the complex field, namely the SI, is captured by CCD camera, and then the information of two original images is extracted from the SI. Although only 50% fragmentary data are extracted, the subsequent CS reconstruction will retrieve a high quality image from the fragmentary information. Compared with the earlier interference- based method, the proposed approach is a process of employing resolution algorithm completely and time-saving since no iterative algorithm is involved in the encryption process. Moreover, the silhouette problem existing in the earlier method is resolved by the proposed method with higher security. Simulation results are presented to support the validity of the proposed approach..
Laser & Optoelectronics Progress
- Publication Date: Mar. 05, 2016
- Vol. 53, Issue 4, 41002 (2016)
Image Enhancement Method Based on Car Secondary Safety System in Smog Days
Li Yamei, and Ren Tingting
In order to solve the problems that fog haze weather vehicle auxiliary safety system image sensor has low contrast and color distortion, an image enhancement method is proposed based on the improved dark channel prior theory. The image atmosphere intensity value estimation method is improved using interval sampling, reIn order to solve the problems that fog haze weather vehicle auxiliary safety system image sensor has low contrast and color distortion, an image enhancement method is proposed based on the improved dark channel prior theory. The image atmosphere intensity value estimation method is improved using interval sampling, removing brightness mutations area. And the transmittance calculating is optimized through region separating. Experimental results show that the proposed algorithm has better performance than other algorithms in real-time, color fidelity and picture contrast ratio..
Laser & Optoelectronics Progress
- Publication Date: Mar. 28, 2016
- Vol. 53, Issue 4, 41003 (2016)
Stereoscopic Image-Quality-Assessment Method Based on Visual Cell Model
Xue Xiaobo, Yu Mei, and He Meiling
Retinal cells of human visual system (HVS) are used as a medium to receive, transmit and understand binocular information when stereo images are viewed. A new stereo image-quality-assessment (SIQA) algorithm aiming to imitate retinal cells is proposed. HVS is mimicked by modeling simple cells and complex cells on the bRetinal cells of human visual system (HVS) are used as a medium to receive, transmit and understand binocular information when stereo images are viewed. A new stereo image-quality-assessment (SIQA) algorithm aiming to imitate retinal cells is proposed. HVS is mimicked by modeling simple cells and complex cells on the basis of the retinal cell characteristics. Binocular fusion view map (BFVM) and binocular cell-based disparity map (BCDM) are obtained via the binocular information processing of the simple-complex cell models. Based on the multiscale structural similarity (MSSIM) method, the binocular fusion quality assessment (BFQA) and binocular stereo perception assessment (BSPA) are respectively implemented to the original or distorted stereo images. The results of BFQA and BSPA are combined to describe the final quality of stereo images. The experimental results demonstrate that the overall Pearson linear correlation indicator reaches 0.94, Spearman rank order correlation coefficient reaches 0.93, which indicate that the proposed model is well consistent with human perception, and also well predict the stero image quality..
Laser & Optoelectronics Progress
- Publication Date: Mar. 04, 2016
- Vol. 53, Issue 4, 41004 (2016)
A Near Infrared Finger Vein Recognition Approach Based on Wavelet Grayscale Surface Matching
Xu Tianyang, Hui Xiaowei, and Lin Sen
Aiming to identify the finger vein and considering the rich texture characteristics of the finger vein, a near infrared finger vein recognition approach based on wavelet grayscale surface matching is proposed. The region of interest of the original image is adjusted by using the histogram equalization, the different reAiming to identify the finger vein and considering the rich texture characteristics of the finger vein, a near infrared finger vein recognition approach based on wavelet grayscale surface matching is proposed. The region of interest of the original image is adjusted by using the histogram equalization, the different resolution images are extracted after decomposition, and the images for matching are constructed. The gray difference surface is obtained by computing the gray difference of two pixels from two different images. The variance is calculated by using the gray difference surface, and is considered as the distance between two feature surfaces of the finger vein images, and the result is used to determine whether the two finger vein images are from the same finger. The comparison experiments are performed with the typical and popular approaches on two databases. The experimental results show that the lowest equal error rate (EER) is 0% and 4.6281% respectively, and the recognition time is only 0.061 s and 0.0502 s, respectively, when the different resolution images are extracted after Haar wavelet decomposition. The superiority and feasibility of the proposed approach is indicated , and high accuracy, good security and fast running speed of the approach are exhibited..
Laser & Optoelectronics Progress
- Publication Date: Feb. 17, 2016
- Vol. 53, Issue 4, 41005 (2016)
Single Image Noise Estimation Based on Image Segmentation and Scatter Statistics of Noise
Hua Weiping, Zhao Jufeng, Li Meng, and Cui Guangmang
Single image noise estimation is important for evaluating image and optical imaging system. A no-reference image noise estimation approach based on noise scatter statistics and accumulation of RGB three channels is proposed. An image is filtered by contrast sensitivity function (CSF) to match the human visual system, aSingle image noise estimation is important for evaluating image and optical imaging system. A no-reference image noise estimation approach based on noise scatter statistics and accumulation of RGB three channels is proposed. An image is filtered by contrast sensitivity function (CSF) to match the human visual system, and the image is segmented by watershed method into sub-image patches with different contents, different patches are achieved free noise estimation using affine reconstruction. Then the pairs of intensity and noise are calculated for patches, and a scatter diagram for RGB three channels of intensity and noise is obtained. Through noise statistics and accumulation , the noise level estimation is achieved. The general database is applied to test the proposed method and other methods in the experiment. Experimental results indicate that the proposed method achieves the same evaluation both objective and subjective..
Laser & Optoelectronics Progress
- Publication Date: Mar. 28, 2016
- Vol. 53, Issue 4, 41006 (2016)
Imaging Systems
Effect of Numerical Aperture on Focal Spot of Radially Polarized Beam in Stimulated Emission Depletion Microscopy
Zhang Hong, Feng Jihong, and Zhang Sen
Stimulated emission depletion (STED) microscopy can break the diffraction limit, which enables scientists to discern cell details smaller than 200 nm. By radially polarized beam through the high numerical aperture (NA) lens, the resolution of STED microscopy systems can be improved. The distribution of radial intensityStimulated emission depletion (STED) microscopy can break the diffraction limit, which enables scientists to discern cell details smaller than 200 nm. By radially polarized beam through the high numerical aperture (NA) lens, the resolution of STED microscopy systems can be improved. The distribution of radial intensity and axial intensity is calculated, furthermore, the effect of NA on the distribution of radial intensity and axial intensity is analyzed. The research shows that the size of axial focal spot is smaller than that of the radial focal spot, the spot size decreases when the NA increases, the full width at half maximum (FWHM) of the depletion beam decreases as well, and the intensity distribution becomes more concentrated. The increase of NA can improve the resolution of STED microscopy systems..
Laser & Optoelectronics Progress
- Publication Date: Feb. 17, 2016
- Vol. 53, Issue 4, 41101 (2016)
Instrumentation, Measurement and Metrology
Research of Statistical Methods for Mirror Surface Figure Error
Zhou Pingwei, and Ma Hongcai
The deformation of optical mirror surface includes rigid-body motion and surface error (distortion). Analyzing the distortion and rigid- body errors plays an important role while evaluating the imaging quality, the environmental adaptability and spatial positional stability of the opto-mechanical system. Removal of rigThe deformation of optical mirror surface includes rigid-body motion and surface error (distortion). Analyzing the distortion and rigid- body errors plays an important role while evaluating the imaging quality, the environmental adaptability and spatial positional stability of the opto-mechanical system. Removal of rigid-body errors is based on the coordinate transformation method. Three methods are described to perform the calculation of root mean square (RMS) value and peak valley (PV) value of distortion. The optical model in ZEMAX software is established through grid sag surface by cubic interpolation algorithm. The RMS spot radius calculated in ZEMAX software is used as the optical standard of mirror distortion. The linearity between RMS value and PV value of distortion and RMS spot radius is taken as the evaluation criteria of the optical performance of three statistical methods for mirror distortion. The results show that the information of distortion calculated by surface fitting method is not complete, the surface fitting method can be applied only when parameters of the surface equation have not been significantly changed. However, the information calculated by normal direction and optical axis direction methods is complete which can be used to measure the image quality of optical system comprehensively..
Laser & Optoelectronics Progress
- Publication Date: Feb. 01, 2016
- Vol. 53, Issue 4, 41201 (2016)
Continuous Terahertz Spectrum Measurement Based on Interferometry
Lu Tielin, Yuan hui, Wu Tong, Zhang Cunlin, and Zhao Yuejin
A method of measuring continuous terahertz frequency spectrum is provided based on Whitman interference theory effect and step-scanned working mode. The continuous terahertz spectrum measurement is calculated theoretically, and the spectrum and the energy density are taken by the computer. The measuring optical structuA method of measuring continuous terahertz frequency spectrum is provided based on Whitman interference theory effect and step-scanned working mode. The continuous terahertz spectrum measurement is calculated theoretically, and the spectrum and the energy density are taken by the computer. The measuring optical structure is set up to obtain the data of terahertz frequency-spectrum and energy density distribution. The measuring data accord well with that of theoretical analysis. The silvering reflect mirror，pyroelectric detector and chopper are used to build the measuring optical path to detect the interference intensity of one point. Frequency spectrum and energy density distribution of 210 GHz continuous terahertz backward-wave oscillator (BWO) and 400 GHz Gunn oscillator are obtained by step-scanned working mode. The accuracy of this measurement is 1 GHz. These results show that, using this method the frequency spectrum and energy density distribution of continuous terahertz wave source can be measured accurately. It provides a strong support for terahertz wave imaging research..
Laser & Optoelectronics Progress
- Publication Date: Mar. 17, 2016
- Vol. 53, Issue 4, 41202 (2016)
Phase Modulation Method to Suppress Decorrelation Phenomenon in Speckle Pattern Interferometry Mearsurement
Cai Huaiyu, Guo Zhendong, Huang Zhanhua, and Li Qingqing
Decorrelation of speckle patterns restricts the implementation of speckle pattern interferometry. A method to increase the speckle correlation and to suppress the decorrelation phenomena is proposed by using a cubic phase mask for the phase modulation. The relationship between the speckle correlation and speckle sizes Decorrelation of speckle patterns restricts the implementation of speckle pattern interferometry. A method to increase the speckle correlation and to suppress the decorrelation phenomena is proposed by using a cubic phase mask for the phase modulation. The relationship between the speckle correlation and speckle sizes is analyzed, and the mechanism is elaborated that the phase modulation suppresses the decorrelation of speckle patterns. The feasibility of the method of phase modulation is verified by simulation. Then the measurement system of phase modulation speckle pattern interferometry is setup. Object lights transmit through a 4f system with a cubic phase mask on the phase surface, therefore the phase modulation can be conveniently achieved. The results of contrast experiments show that the transverse correlation size and the longitudinal correlation size of modulated speckle patterns can be increased by about 1.7 and 2.5 times, respectively. The decorrelation of speckle patterns can be effectively suppressed. Moreover, the correlation area of speckle pattern interferometry, in which well-observable fringes are obtained, can be increased by about 2.5 times, and the partial contrast of fringes in speckle pattern interferometry can be enhanced..
Laser & Optoelectronics Progress
- Publication Date: Feb. 17, 2016
- Vol. 53, Issue 4, 41203 (2016)
A Hole Diameter Measurement Model on Machine Based on Single Laser Beam Rotation
Liu Xinbo, Wang Zhong, Luo Qingyue, and Fu Luhua
The hole inner diameter measurement for large precise workpieces is very common on site, and the current measurement methods are inconvenient. A single laser rotation measurement method is presented. Through the analysis of limit distance between a fixed point of the rotary axis and the measuring points with a sensor’sThe hole inner diameter measurement for large precise workpieces is very common on site, and the current measurement methods are inconvenient. A single laser rotation measurement method is presented. Through the analysis of limit distance between a fixed point of the rotary axis and the measuring points with a sensor’s value, a searching model with limiting point can be set up for any surface. The operation method is suitable for measuring workpiece on machine. The hole diameter can be measured by searching the end points in the direction of diameter on the basis of the model and with the comparative measurement combined. The model can be implemented easily because it just needs a rotating spindle without any encoders or other auxiliary parts. The experimental results show that the method is valid. It is of great significance in the integration of machining and measurement for the hole on large workpieces..
Laser & Optoelectronics Progress
- Publication Date: Mar. 22, 2016
- Vol. 53, Issue 4, 41204 (2016)
Lasers and Laser Optics
Bad-Cavity Raman Laser Based on Lattice-Trapped Cesium Atoms
Peng Yu, Liu Pengfei, and Li Wei
We propose a bad-cavity laser based on the Raman transition of cesium-133 atoms that collectively emit photons into the wide mode of a low finesse resonator, which is known as the optical bad-cavity regime. The spinspin correlation, which characterizes the collective effect, is demonstrated. We theoretically predict thWe propose a bad-cavity laser based on the Raman transition of cesium-133 atoms that collectively emit photons into the wide mode of a low finesse resonator, which is known as the optical bad-cavity regime. The spinspin correlation, which characterizes the collective effect, is demonstrated. We theoretically predict that the optical radiation has an extremely narrow linewidth in the 98×10-2 mHz range, and that a power level of 7×10-10 W is possible..
Laser & Optoelectronics Progress
- Publication Date: Mar. 30, 2016
- Vol. 53, Issue 4, 41402 (2016)
Research Progress of Tangential Airflow Impacting on Laser Irradiation
Zhang Wenjie, Meng Wen, Li Yunxia, and Liang Luyang
Tangential airflow as a kind of environmental factors can impact on the laser irradiation. In recent years, the tangential airflow effects on laser irradiation are extensively studied by some scholars at home and abroad, including the influence of different natures of the airflow environment, different intensities of tTangential airflow as a kind of environmental factors can impact on the laser irradiation. In recent years, the tangential airflow effects on laser irradiation are extensively studied by some scholars at home and abroad, including the influence of different natures of the airflow environment, different intensities of tangential airflow on laser irradiation. Its influence factors mainly include oxidation reaction promotion, convective heat transfer coefficient increase and aerodynamics. The couple interaction between the factors is analyzed. But the material research of tangential airflow laser irradiation effect is not enough, and the analysis of fracture before melting is not clear, which need further research for improvements..
Laser & Optoelectronics Progress
- Publication Date: Feb. 26, 2016
- Vol. 53, Issue 4, 41403 (2016)
Intensity Distribution Characteristics of Partially Coherent Flat-Topped Beam Combination Projected on Cavity Wall
Chen Mingyu, Li Xiaoyan, Chen Ziyang, Pu Jixiong, and Lin Zhili
A model is established to study the propagation of the lens- focused laser beam combination in the hohlraum in the progress of laser indirect driving. As for all laser beams in cone rings projected on the hohlraum wall, the incoherent superposition characteristics of intensity distribution of focal spots are investigatA model is established to study the propagation of the lens- focused laser beam combination in the hohlraum in the progress of laser indirect driving. As for all laser beams in cone rings projected on the hohlraum wall, the incoherent superposition characteristics of intensity distribution of focal spots are investigated based on the Collins formula. The effects of relative spatial coherence degree, lens focusing F number and defocusing amount on the intensity distribution uniformity of focal spots projected on the target wall are discussed in detail. As the spatial coherence degree increases, the spot intensity of incoherent superposition increases, the light intensity fluctuation becomes more apparent, and the uniformity of the top light intensity distribution deteriorates. The spot intensity also increases with the increase of focusing F number, the intensity fluctuation is more violent, and the uniformity of the top light intensity distribution deteriorates. As the defocusing amount increases, the light intensity on the target chamber surface is reduced, the volatility degree and the difference of light intensity peak are smaller while the top intensity distribution becomes more homogenous..
Laser & Optoelectronics Progress
- Publication Date: Mar. 29, 2016
- Vol. 53, Issue 4, 41404 (2016)
Machine Vision
Study of Shape Matching and Localization Algorithm Based on Polygon Fitting
Bai Yu, Zhang Lichao, Shi Yusheng, and Yan Ran
In the control procedure of process based on machine vision, the key is the location of the special point on work piece. The difficulty lies in how to construct a shape descriptor that can meet the needs of shape matching, precision of location and real-time at the same time. To solve the problems above，a kind of shapeIn the control procedure of process based on machine vision, the key is the location of the special point on work piece. The difficulty lies in how to construct a shape descriptor that can meet the needs of shape matching, precision of location and real-time at the same time. To solve the problems above，a kind of shape matching and localization algorithm based on polygon fitting is proposed. The method is aimed at the planar two-dimension (2D) contour. The key points on the contour are gained by the polygon fitting processing, then the polygon is used to construct a shape description and the key points are used to make location, to obtain the transformation relationship between template contour and target contour. The results show that by using the proposed rotation invariant shape descriptor, high accuracy and good real-time performance of shape matching and location algorithm can be gained..
Laser & Optoelectronics Progress
- Publication Date: Mar. 06, 2016
- Vol. 53, Issue 4, 41501 (2016)
Apparent Magnitude Measurement of Geosynchronous Orbit Space Object Based on Phong Model
Liu Hao, Du Xiaoping, and Gou Ruixin
There are a lot of spatial objects running along the geosynchronous orbit (GEO). Estimation of the shape and attitude of space objects by using light curves provides a method for object tracking, identification and surveillance. The temporal and spatial relationship among the sun, satellite and observation station undeThere are a lot of spatial objects running along the geosynchronous orbit (GEO). Estimation of the shape and attitude of space objects by using light curves provides a method for object tracking, identification and surveillance. The temporal and spatial relationship among the sun, satellite and observation station under different orbit parameters is obtained via coordinate transformation by using the STK software. According to the definition of apparent magnitude, the calculation model suitable for cube, prism and cylinder objects is derived with the facet method based on the Phong model. Through comparison with the measured data, it is demonstrated that the simulation error of the model is about 3%, the simulation result is far better than the result obtained by the apparent magnitude model only characterized by the diffuse reflectance. Based on the Matlab software, the light curves of satellites with different segments, shapes and sizes are simulated. The study shows that the nonlinear filtering technique is adopted for inversion if obtained light curves have better quality, otherwise the two-facet analytical model is used. The research offers a reference for the inversion based on light curves..
Laser & Optoelectronics Progress
- Publication Date: Mar. 08, 2016
- Vol. 53, Issue 4, 41502 (2016)
Materials
Multi-Channel Filter Based on Symmetric Nested Photonic Crystals Quantum Well
Xiong Cuixiu, Deng Yangbao, and Deng Shuguang
In order to achieve the function of multi-channel photonic filtering, the symmetric nested photonic crystals quantum well (BAB)k (AB)m (BAB)n (BA)m (BAB)k is designed. The transmission spectra of photonic quantum well are calculated based on transmission matrix method. The effect of periods number of the well photonic In order to achieve the function of multi-channel photonic filtering, the symmetric nested photonic crystals quantum well (BAB)k (AB)m (BAB)n (BA)m (BAB)k is designed. The transmission spectra of photonic quantum well are calculated based on transmission matrix method. The effect of periods number of the well photonic crystals and refractive index on transmission spectral peak is analyzed. The results show that three groups of transmission peaks appear in the main forbidden band of photonic quantum well. Due to the coupling between the outer wells (AB)m and (BA)m , the second and the third groups of transmission peaks have dual-line structures. The numbers, location of transmission peaks and internal between the dual- line structures are related to the periods number of the well photonic crystals and refractive index. In the main forbidden band，there are 2m+n+3 (with odd number m) or 2m+ n+1 (with even number m) narrow transmission peaks. With the increasing of the periods number of the inner or outer wells, the frequency interval of the double lines becomes narrower, and the dual transmission peaks move closer to the center frequency. With the increasing of refractive index of high- refractive medium, the frequency internal between the double lines narrows down and the dual transmission peaks move away from center frequency. However, when the refractive index of low refractive index medium is increased, the frequency internal between the double lines will be broadened and the dual transmission peaks move closer to the center frequency. The results have a certain reference value for design of multi-channel photonic filter..
Laser & Optoelectronics Progress
- Publication Date: Feb. 26, 2016
- Vol. 53, Issue 4, 41601 (2016)
Anti-Reflection Characteristics of Photonic Crystals
Wang Ting, Liang Binming, Jiang Qiang, Cao Heng, and Gao Lun
The light propagation characteristic in a two-dimensional triangle lattice photonic crystal is studied by finite-difference time-domain method. Based on reflection of transverse magnetic (TM) wave, the influences on antireflection characteristics of the photonic crystal resulting from incident angle, wavelength and temThe light propagation characteristic in a two-dimensional triangle lattice photonic crystal is studied by finite-difference time-domain method. Based on reflection of transverse magnetic (TM) wave, the influences on antireflection characteristics of the photonic crystal resulting from incident angle, wavelength and temperature are systematically studied. The simulation results show that the great residual reflectivity of TM wave can be achieved in wide range of wavelength and incident angle by setting a suitable wave guide width parameter, which demonstrates a good performance in anti-reflection. Moreover, the temperature change has slight impact on anti-reflection, which shows a good stability in temperature drifting..
Laser & Optoelectronics Progress
- Publication Date: Mar. 17, 2016
- Vol. 53, Issue 4, 41602 (2016)
Optical Design and Fabrication
Design and Optimization of Anti-Glare LED Mining Lamp
Chen Chaoquan, Wang Min, and Luo Shirui
A kind of anti-glare LED mining lamp is designed, by adding a infundibular free-form surface reflector into it. The workpiece surface is optimized to make the inner surface uniform. It greatly reduces the glare value of the mining lamp. With SolidWorks modeling and TracePro simulation analysis, the glare value is reducA kind of anti-glare LED mining lamp is designed, by adding a infundibular free-form surface reflector into it. The workpiece surface is optimized to make the inner surface uniform. It greatly reduces the glare value of the mining lamp. With SolidWorks modeling and TracePro simulation analysis, the glare value is reduced from 52.8 to 24, which can meet the requirements of all kinds of sports lighting. Further analysis of the results from the visual of human eye shows that, it can see the very bright LED chips and the illumination uniformity of the inner surface is only 0.383 before optimization. It is very dazzling and may cause eyes damage when staring. After optimization, only the inner surface but not the LED chips can be seen, its illumination uniformity is up to 0.824 and the average illumination value is also greatly reduced, the human eyes can look directly at the lamp without glare. Its anti-glare advantage is outstanding when compared with the existing lamps, and has a broad market prospect..
Laser & Optoelectronics Progress
- Publication Date: Mar. 11, 2016
- Vol. 53, Issue 4, 42201 (2016)
Optical Devices
Research on the Resonance Modes Separation of the Subwavelength Ring-Shaped Demultiplexer
Wang Liu, and Zeng Yaping
A subwavelength ring-shaped three channels metal-insulator-metal waveguide demultiplexer is proposed. The transmission characteristics are investigated using finite-difference time-domain method from visible to near infrared spectrum. The multi order resonance phenomenon is found in the ring when the electromagnetic waA subwavelength ring-shaped three channels metal-insulator-metal waveguide demultiplexer is proposed. The transmission characteristics are investigated using finite-difference time-domain method from visible to near infrared spectrum. The multi order resonance phenomenon is found in the ring when the electromagnetic waves satisfy the resonance condition. The second, third, fourth order resonance waves can be separated by optimizing output ports next to the ring. Moreover, the resonance wavelengths of the ring can be controlled by setting the radius of the ring. The structure has light trapping and transmission functions, which can solve the modes separation transmission of signal. This design structure may be useful in optical integration and communication..
Laser & Optoelectronics Progress
- Publication Date: Mar. 22, 2016
- Vol. 53, Issue 4, 42301 (2016)
Fabrication of Large Size 1064 nm HfO2/SiO2 Narrow-Band Filters with High Laser Damage Threshold
Wu Xiaoming, Li Xin, Wang Yijian, and Jiao Hongfei
Narrowband filters with central wavelength 1064 nm are key optical elements used in the large scale solid state laser facility. In order to fabricate a filter with large size and high precision, the influence of monitoring wavelength on signal noise ratio and stability is investigated. Moreover, the monitoring strategyNarrowband filters with central wavelength 1064 nm are key optical elements used in the large scale solid state laser facility. In order to fabricate a filter with large size and high precision, the influence of monitoring wavelength on signal noise ratio and stability is investigated. Moreover, the monitoring strategy is optimized to satisfy the precision need for fabricating a narrowband filter. Film spectra analysis in fabrication process indicates that the actual thickness of HfO2 will smaller than design value gradually, and the actual thickness of SiO2 will greater than design value gradually, with the proceed of coating. The thickness error as a result of the different variation tendency for HfO2 and SiO2 in the evaporation process, and the mask plate induced error are key points of affecting the bandpass property. One 200 mm × 200 mm size narrowband filter with 5 nm full width at half maximum (FWHM) and over 19.5 J/cm2 (3 ns) laser damage threshold at 1064 nm is successfully fabricated..
Laser & Optoelectronics Progress
- Publication Date: Mar. 21, 2016
- Vol. 53, Issue 4, 42302 (2016)
Remote Sensing and Sensors
Research of Optical Fiber Fabry-Perot Acoustic Vibration Sensing Demodulation System Based on Dual Tunable Lasers
Fan Zhuo, Wang Shuang, Liu Tiegen, Liu Kun, He Pan, and Zhang Tianhao
In order to realize the Fabry-Perot (F-P) acoustic vibration sensing demodulation working under wide range of optical fiber F-P initial cavity length and cavity length shift, a kind of quadrature phase extracting method based on dual tunable lasers is proposed. The range of initial cavity length which keeps quadrature In order to realize the Fabry-Perot (F-P) acoustic vibration sensing demodulation working under wide range of optical fiber F-P initial cavity length and cavity length shift, a kind of quadrature phase extracting method based on dual tunable lasers is proposed. The range of initial cavity length which keeps quadrature phase is calculated theoretically. The influence of initial cavity length drift on signal demodulation is studied by theoretical simulation and experiment. Initial cavity length drift of 0~2.2 μm is achieved by changing temperature. In this case, interference intensity demodulation method and quadrature phase extracting method are compared and analyzed: relative change of demodulation signal amplitude by quadrature phase extracting method is less than 5.3% ; the stability of demodulation signal amplitude by quadrature phase extracting method is 12.4 times as much as that by interference intensity demodulation method. Initial cavity length of 55~130 μm is realized by wavelength tuning compensation and relative change of demodulation signal amplitude is less than 4.9%..
Laser & Optoelectronics Progress
- Publication Date: Mar. 28, 2016
- Vol. 53, Issue 4, 42801 (2016)
Dense Wavelength Division Multiplexing-Based Demodulation of Fiber Bragg Grating Pressure Sensor
Wang Hui, Yang Yang, and Liu Bing
By applying Bourdon tube and tunable filter technology, a fiber Bragg grating pressure sensor is designed. The 50 GHz dense wavelength division multiplexing- based and wavelength demodulation algorithm are adopted to locate the exact position of narrowband reflection spectrum in the channel. The results of wavelength dBy applying Bourdon tube and tunable filter technology, a fiber Bragg grating pressure sensor is designed. The 50 GHz dense wavelength division multiplexing- based and wavelength demodulation algorithm are adopted to locate the exact position of narrowband reflection spectrum in the channel. The results of wavelength demodulation system show that the fiducial error is only 0.5% under the range of 0~6 MPa, and the resolution of the wavelength which comes from the measured experimental can reach 0.1 pm. The demodulation sensitivity of the sensor resolution is 3×103 nW/MPa..
Laser & Optoelectronics Progress
- Publication Date: Mar. 17, 2016
- Vol. 53, Issue 4, 42803 (2016)
Reviews
Biological Laser Printing Technology and Its Applications
Chen Yanping, Yang Rusong, Liu Long, Wei Li′an, Feng Ying, and Xiang Yang
Biological laser printing (BioLP) is a new cell printing technology, which can precisely print a trace amount of biomaterial droplets at different locations without bioactive damage. An overview of the biological laser printing is provided, including theory, equipment, key treatment techniques and latest progress. FinaBiological laser printing (BioLP) is a new cell printing technology, which can precisely print a trace amount of biomaterial droplets at different locations without bioactive damage. An overview of the biological laser printing is provided, including theory, equipment, key treatment techniques and latest progress. Finally, the challenges and future development of BioLP is forecasted..
Laser & Optoelectronics Progress
- Publication Date: Feb. 17, 2016
- Vol. 53, Issue 4, 40001 (2016)
Spectroscopy
Detection of Chromium Content in Soybean Oil by Laser-Induced Breakdown Spectroscopy
Wu Yiqing, Sun Tong, Liu Xiuhong, Mo Xinxin, and Liu Muhua
Laser-induced breakdown spectroscopy (LIBS) is used to detect chromium content in soybean oil. A series of soybean oil samples with different chromium concentrations are used, and an AvaSpec two-channel spectrometer is used to acquire spectra of samples in the wavelength range of 206.28~481.77 nm. According to the LIBSLaser-induced breakdown spectroscopy (LIBS) is used to detect chromium content in soybean oil. A series of soybean oil samples with different chromium concentrations are used, and an AvaSpec two-channel spectrometer is used to acquire spectra of samples in the wavelength range of 206.28~481.77 nm. According to the LIBS spectra, several primary characteristic spectral lines of the Cr element are confirmed, then linear regression or least squares support vector machine (LS-SVM) method is used to develop univariate, bivariate and multivariate calibration models. Cr content of the samples is predicted by these calibration models. The results indicate that the performance of bivariate and multivariate calibration models is superior to that of the univariate calibration model, and the performance of the multivariate calibration model developed by LS-SVM is the best. The average relative error (RE) of sample prediction results in univariate and bivariate calibration models is 14.16% and 11.58%, respectively. The average RE of sample prediction in multivariate calibration models developed by linear regression and LS-SVM is 10.95% and 4.97%, respectively. According to these results, the LIBS technique has some feasibility to detect Cr content in soybean oil, and the LS-SVM method can improve the prediction accuracy of calibration models effectively..
Laser & Optoelectronics Progress
- Publication Date: Jan. 13, 2016
- Vol. 53, Issue 4, 43001 (2016)
Quantitative Analysis of Unburned Carbon in Fly Ash by Laser-Induced Breakdown Spectroscopy in Different Atmosphere
Bian Jintian, Yin Kejing, Yao Shunchun, Lu Jidong, and Xu Jialong
The spectral line C I 247.86 nm which is widely used to analyze unburned carbon in fly ash by laser-induced breakdown spectroscopy (LIBS) shows strong spectrum interference. Another spectral line C I 193.09 nm located in deep ultraviolet area is frequently used to avoid the strong interference. However, it is strongly The spectral line C I 247.86 nm which is widely used to analyze unburned carbon in fly ash by laser-induced breakdown spectroscopy (LIBS) shows strong spectrum interference. Another spectral line C I 193.09 nm located in deep ultraviolet area is frequently used to avoid the strong interference. However, it is strongly absorbed by oxygen in air, which affects the accuracy of quantitative analysis. In order to improve the performance of quantitative analysis by using C I 193.09 nm line, the spectrometer is filled with argon and the argon environment is formed in the region where the plasma emerges. The quantitative analysis results of unburned carbon in air and argon atmosphere by using C I 193.09 nm line are compared. The results indicate that the line intensity, signal- to- noise ratio, repeated measurement precision and limit of detection are improved significantly. Meanwhile, the absolute error between predicted concentration and actual concentration for two test samples is reduced to 0.02% and 0.42% (mass fraction), respectively in argon atmospheric environment, and the limit of detection is also reduced to a relatively low level of 0.37% (mass fraction)..
Laser & Optoelectronics Progress
- Publication Date: Feb. 17, 2016
- Vol. 53, Issue 4, 43002 (2016)
Spectra of Twin Primary Rainbows Scattered by a Coated Cylinder
Song Feihu, and Li Zhenfeng
Diameter of a homogeneous cylinder can be determined with the spectrum of the rainbow pattern, formed by the scattering ray interference when the cylinder is illuminated by a laser. As for a coated cylinder, the intensity distribution and spectral characteristics of the twin primary rainbows under different cylinder siDiameter of a homogeneous cylinder can be determined with the spectrum of the rainbow pattern, formed by the scattering ray interference when the cylinder is illuminated by a laser. As for a coated cylinder, the intensity distribution and spectral characteristics of the twin primary rainbows under different cylinder sizes are investigated via theoretical simulation and experiments. The numerical simulation based on Debye theory is used to obtain the intensity distribution spectra and four characteristic frequency peaks are obtained, and how they are formed is also illustrated. The frequency peak F3, with its origin similar to that of the ripple structure formed in a homogeneous cylinder, is then analyzed. The results show that F3 increases with the outer diameter linearly and the slope is also slightly affected by the internal diameter and refractive index of the coated cylinder. However, there is no obvious relationship between the internal diameter and F3. The experimental research is implemented by building a system to capture the rainbow pattern and its spectrum is analyzed. The relative error of outer diameter about 2% can be determined experimentally, when the internal diameter and the coated refractive index are fixed..
Laser & Optoelectronics Progress
- Publication Date: Feb. 26, 2016
- Vol. 53, Issue 4, 43004 (2016)
Thin Films
Determination of Optical Constants and Thickness of Polymer Semiconductor Thin Film by Reflectivity Fitting Method
Li Guolong, Zhong Jingming, Wang Lihui, Li Jin, He Lijun, Li Haibo, and Gao Mangmang
Optical constants (refractive index and extinction coefficient) of polymer semiconductor thin films are of great significance to perform optimization design. The Forouhi-Bloomer (F-B) dispersion models are applied by fitting reflectivity curves of P3HT (poly(3-hexylthiophene)):PCBM ([6,6]-phenyl-C61-butyric acid methylOptical constants (refractive index and extinction coefficient) of polymer semiconductor thin films are of great significance to perform optimization design. The Forouhi-Bloomer (F-B) dispersion models are applied by fitting reflectivity curves of P3HT (poly(3-hexylthiophene)):PCBM ([6,6]-phenyl-C61-butyric acid methyl ester), MEH-PPV (poly[2-methoxy-5-(2′ethyl-hexyloxy)-1,4-phenylenevinylene]):PCBM, and PEDOT (poly (3,4-ethylene dioxythiophene)):PSS (polystyrenesulfonate). The optical constants and thickness are calculated, and two reflectance curves fit well. The thickness mismatch between the fitting and measurement results is less than 3%. Based on this method, the influence of thermal annealing on the P3HT:PCBM film surface morphology and the optical constants is analyzed. The maximum refraction index of P3HT:PCBM increases from 1.95 to 2.16 in the wavelength range of 550 nm to 700 nm after the thermal annealing process at 110 ℃ and the peak of extinction coefficient shifts to longer wavelength..
Laser & Optoelectronics Progress
- Publication Date: Jan. 13, 2016
- Vol. 53, Issue 4, 43101 (2016)
Vision, Color, and Visual Optics
Transmission Spectrum Modulator Based on Metallic Nanowire Gratings
Shen Fafu, Cui Jie, Sun Nanling, and Ye Zhicheng
Metallic nanowire gratings have great potential to be used in display devices attributing to the unique surface plasmon resonant color shift by changing the refractive index of the ambient media. The modulator has the advantages of simple structure, high chromaticity and contrast, etc. Three pitches of bilayer metallicMetallic nanowire gratings have great potential to be used in display devices attributing to the unique surface plasmon resonant color shift by changing the refractive index of the ambient media. The modulator has the advantages of simple structure, high chromaticity and contrast, etc. Three pitches of bilayer metallic nanowire gratings with red, green and blue colors are respectively designed by simulation. In the experiment, the gratings with a pitch of 520 nm and an aluminum thickness of 50 nm are fabricated. The switching from bright green color state to dark state is achieved by changing the ambient medium from air to sucrose solution, and the contrast can reach 122. The feasibility of color display and adjustable brightness is verified theoretically and experimentally, which provides a new design scheme for the electro-wetting display devices in the future..
Laser & Optoelectronics Progress
- Publication Date: Mar. 01, 2016
- Vol. 53, Issue 4, 43301 (2016)
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