Journals >Laser & Optoelectronics Progress
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2015
Volume: 52 Issue 4
38 Article(s)
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Detectors
Terahertz Time-Domain Spectroscopy Rapid Data Acquisition Based on Closed-Loop Control
Huang Zhanhua, Hu Zixiao, He Mingxia, Long Ningbo, and Liu Yang
As a new spectral analysis method, terahertz time-domain spectroscopy (THz-TDS) is rapidly developing in many fields. Conventional THz-TDS systems have a long detection time and a small amount of collected data. To improve THz-TDS system′s detection speed and accuracy, a rapid THz-TDS data acquisition and control systeAs a new spectral analysis method, terahertz time-domain spectroscopy (THz-TDS) is rapidly developing in many fields. Conventional THz-TDS systems have a long detection time and a small amount of collected data. To improve THz-TDS system′s detection speed and accuracy, a rapid THz-TDS data acquisition and control system based on closed-loop control are presented. The system can perform continuous scanning and data collection with a high speed. When performing step scanning, it can get real-time location information of the optical delay line by the delay line′ s feedback signal, and thus can complete automatic scanning rapidly. By acquiring multiple data continuously in a single step, the accuracy of acquisition in every step is improved. Results show that the system can take full advantage of the optical delay line to achieve a highest data acquisition speed of 500 kHz. When the step length is 5 mm, the time of continuous acquisition of 1000 data is only 86.34 ms, which means the system can perform automatic and rapid acquisition of terahertz time-domain pulse signal with high precision..
Laser & Optoelectronics Progress
- Publication Date: Mar. 21, 2015
- Vol. 52, Issue 4, 40401 (2015)
Fiber Optics and Optical Communications
Experimental Study of Temperature Characteristics of Polarization Coupling Intensity of Photonic Crystal Fiber Coil
Li Yan, Sun Yanfeng, Song Jingming, and Wang Xu
Photonic crystal fibers (PCFs) are investigated. The polarization cross-coupled distributions of both polarization-maintaining photonic crystal fiber coil and ordinary polarization-maintaining fiber coil are tested at various temperatures utilizing white light interferometers. Changes of polarization coupling intensitiPhotonic crystal fibers (PCFs) are investigated. The polarization cross-coupled distributions of both polarization-maintaining photonic crystal fiber coil and ordinary polarization-maintaining fiber coil are tested at various temperatures utilizing white light interferometers. Changes of polarization coupling intensities of fixed polarization cross-coupled points in fiber coils at different temperatures are also analyzed. The obtained results show that, in the temperature range between -40 ℃ and 50 ℃, the maximum change rate of polarization coupling intensity of photonic crystal fiber coil is 0.97%, while that of ordinary polarization maintaining fiber coil is 4.71%, which is almost five times as the former one. Thus it can be concluded that the coupling intensity of photonic crystal polarization maintaining fiber coil possesses better stability against temperature changes than that of ordinary polarization-maintaining fiber coil..
Laser & Optoelectronics Progress
- Publication Date: Mar. 31, 2015
- Vol. 52, Issue 4, 40601 (2015)
Experimental Study of the Transmission in Multimode Fiber with a Single Mode Laser
Chen Han, Zhou Shuzhen, Yu Haijuan, and Lin Xuechun
The transmitted beam through the large-core multimode fiber is investigated by using CCD beam profiler. The energy distribution and beam quality are discussed, thus the transmission characteristics of the multimode fiber are obtained. The single mode laser is chosen as a testing light source, and the study is conductedThe transmitted beam through the large-core multimode fiber is investigated by using CCD beam profiler. The energy distribution and beam quality are discussed, thus the transmission characteristics of the multimode fiber are obtained. The single mode laser is chosen as a testing light source, and the study is conducted by applying multimode fiber with different core diameters and lengths. The results show that the multimode fibers have shaping effect on the input beam including beam quality degradation and homogenization of the energy distribution. Besides, the deterioration of the beam quality and the homogenization effect have dependence on the parameters of the multimode fiber. The larger diameter of the multimode fiber leads to more serious deterioration of the beam quality as well as better homogenization effect. A positive correlation between the transmitting length and the homogenization effect is also found. This study can provide a simple and effective scheme for the shaping of the single mode laser. By selecting multimode fibers with various parameters, the quasi uniform beams with different characteristics can be got to meet special laser processing demand..
Laser & Optoelectronics Progress
- Publication Date: Mar. 31, 2015
- Vol. 52, Issue 4, 40602 (2015)
Design on Receiving Optical Antenna with Wide Field of View for Multi-Spectral Light Communication
Guo Lei, Zhang Lijun, Tang Yi, Bai Tingzhu, Zhang Xuebin, and Huang Heqing
A new kind of optical antenna for multi-spectral light communication with large gain and wide field of view is proposed.The fore-receiving optical antenna is based on the reversed telephoto optical system and consists of three negative lenses in front and four positive lenses behind.By theoretical analysis and optimizaA new kind of optical antenna for multi-spectral light communication with large gain and wide field of view is proposed.The fore-receiving optical antenna is based on the reversed telephoto optical system and consists of three negative lenses in front and four positive lenses behind.By theoretical analysis and optimization with Zemax,the field of view (FOV) reaches 90° and the optical gain is up to 115,and the size is also compact.The antenna is appropriate for multi-spectral light communication.By cooperating with multi-spectral wavelength division multiplexing system,its FOV is up to 90°×22° and its optical gain is 20.Moreover,the antenna can be independently used as an optical system for wide FOV imaging systems and front-end system of imaging spectrometers..
Laser & Optoelectronics Progress
- Publication Date: Mar. 04, 2015
- Vol. 52, Issue 4, 40603 (2015)
Study of New Type of Optical Information Coding and Modulation Technology in Radio over Fiber
Li Guang, Chen Yin, and Huang Xuguang
A new type of optical information coding and modulation combination scheme is proposed, and the high speed long distance radio over fiber (RoF) communication is realized by using double photoelectric arms coherent modulation and new optical information coding technology. In the first modulation, the effective bandwidthA new type of optical information coding and modulation combination scheme is proposed, and the high speed long distance radio over fiber (RoF) communication is realized by using double photoelectric arms coherent modulation and new optical information coding technology. In the first modulation, the effective bandwidth of signal code is the half of the effective bandwidth of non return to zero code of ordinary optical. In the second modulation, the ultra- high frequency millimeter wave is modulated to the light wave in order to realize radio over fiber transmission. By advanced optical system development software(OptiSystem) simulation, the simulation results show that when eye diagram is nomal and the bit error rate of transmission system can be controlled, the transmission distance of code in radio over fiber communication system is 1.6×106 m, and the speed is 40 Gb/s..
Laser & Optoelectronics Progress
- Publication Date: Mar. 31, 2015
- Vol. 52, Issue 4, 40604 (2015)
Holography
Study of the Generalized Linear Reconstruction Algorithm in the Pre-Magnification Digital Holographic Technology with Spherical Reference Wave
Ma Yanxiao, Wang Huaying, and Gao Yafei
In order to improve the accuracy and the speed of reconstructed image in the pre-magnification digital holographic microscopy system with spherical reference wave, the generalized linear reconstructing algorithm based on homomorphic signal processing (GL-HSP) is analyzed by computer simulation and experimental verificaIn order to improve the accuracy and the speed of reconstructed image in the pre-magnification digital holographic microscopy system with spherical reference wave, the generalized linear reconstructing algorithm based on homomorphic signal processing (GL-HSP) is analyzed by computer simulation and experimental verification. Through using the algorithms based on fast Fourier transform (FFT) method and GL-HSP algorithm to reconstruct the intensity and phase information of texted samples, the reconstructed results clearly show that the GL-HSP algorithm not only has higher reconstructed accuracy, but also has higher reconstructed speed. As the GL-HSP algorithm chooses the whole quadrant as the filtered area, it has all of the high frequencies. So the GL-HSP algorithm is more suitable for high-accuracy reconstructing the micro-subjects. At the same time, the results of standard deviation in the experimental date quantitatively show the superiority of the GL-HSP algorithm..
Laser & Optoelectronics Progress
- Publication Date: Mar. 13, 2015
- Vol. 52, Issue 4, 40901 (2015)
Imaging Systems
Contactless Driver Fatigue Detection and Warning System Based on Eye State Information
Li Jianping, Niu Yanxiong, Yang Lu, Zhang Ying, and Lü Jianming
The fatigue warning system is very important to guarantee driver′s safe driving. The discrete fatigue estimate model of percentage of eyelid closure over the pupil time bases on image process of eyes is established, and the driver fatigue status monitoring and warning are realized. Eye images acquisition is realized byThe fatigue warning system is very important to guarantee driver′s safe driving. The discrete fatigue estimate model of percentage of eyelid closure over the pupil time bases on image process of eyes is established, and the driver fatigue status monitoring and warning are realized. Eye images acquisition is realized by complementary metal-oxide-semiconductor camera with near-infrared lamps shine. Adaboost algorithm is applied to locate the eyes, and Harris corner detection is used to obtain the information about sight of eyes. Grade warning level is designed by the adjustable warning threshold based on the fatigue estimate model. The experimental results show that the system can provide under 1.5 s reaction time, 4% false alarm rate, and possess good real-time and anti-jamming characteristic under certain conditions..
Laser & Optoelectronics Progress
- Publication Date: Mar. 25, 2015
- Vol. 52, Issue 4, 41101 (2015)
Discrimination of Maize Seeds by Near Infrared Ray Hyperspectral Imaging with Local Learning
Tang Jinya, Huang Min, and Zhu Qibing
The local learning algorithm is introduced into the optimal wavelength selection of near infrared ray hyperspectral imaging of maize seeds. These obtained wavelengths are used to develop a discrimination model coupled with partial least squares discriminant analysis to implement the rapid discrimination of maize seeds The local learning algorithm is introduced into the optimal wavelength selection of near infrared ray hyperspectral imaging of maize seeds. These obtained wavelengths are used to develop a discrimination model coupled with partial least squares discriminant analysis to implement the rapid discrimination of maize seeds using less wavelengths. 256 near infrared ray hyperspectral images between 874~1734 nm wavelengths are acquired using a hyperspectral imaging system for 720 maize seed samples including six varieties. Local learning algorithm is proposed to calculate the weight values of wavelengths, and the optimal wavelengths are selected according to the weight values. The experimental results show that local learning algorithm can effectively select the optimal wavelengths. Using 13 optimal wavelengths, six groups of maize seeds achieve an average purity of 95.97%, which can provide a suitable technical way for the rapid discrimination of maize seeds..
Laser & Optoelectronics Progress
- Publication Date: Mar. 25, 2015
- Vol. 52, Issue 4, 41102 (2015)
Lasers and Laser Optics
Design of High Efficiency Fiber Coupling System Based on Microlens Array
Wang Yanhong, Wang Haiwei, and Wang Gao
The fiber coupling is an important method of semiconductor laser integration for improving light beam quality and remote communication. But due to the limits of semiconductor laser volume and thermal dissipation, the output light after integration of laser has still larger beam parameter product (BPP), which is not easThe fiber coupling is an important method of semiconductor laser integration for improving light beam quality and remote communication. But due to the limits of semiconductor laser volume and thermal dissipation, the output light after integration of laser has still larger beam parameter product (BPP), which is not easy to couple with a single multimode fiber. The packing ratio of fiber bundle is another factor to limit direct couple with fiber bundle. In order to get high efficiency couple integration light source of multi semiconductor laser into fiber bundle, optical amplify system is adopted to compress the beam diameter. Microlens array is used as coupling element, which makes the pupil of lenslet image on the end of fibers. One- to- one coupling is achieved and a fiber coupling system with no loss in theory is come ture. To improve aberration effect due to rim ray, hollow light pipe is employed to further homogenize light field. Furthermore, divergence angle of rim ray is reduced and its imaging quality is improved. The coupling efficiency of optimized system can be up to 98%. The system utilizes microlens array for beam splitting and imaging, which overcome the shortages of larger BPP and not easy to couple with single fiber. The system makes the pupil of microlens to image at the end of fibers and gets the same arrange spots image with that of the fiber bundle, thus, coupling efficiency of both light beam and fibers are improved..
Laser & Optoelectronics Progress
- Publication Date: Jan. 01, 1900
- Vol. 52, Issue 4, 41401 (2015)
Microstructure Analysis of Fiber Laser Welding between E36 and 304 Stainless Steel
Liu Dongyu, Li Dong, Li Kaibin, and Chen Qianqian
E36 high-strength steel and 304 austanitic stainless steel are welded by fiber laser. Microstructure is investigated by means of optical microscopy (OM), energy disperse spectroscopy (EDS), scanning electron microscopy (SEM) and X-ray Diffraction (XRD). Micro hardness of weld is tested by micro hardness tester. The resE36 high-strength steel and 304 austanitic stainless steel are welded by fiber laser. Microstructure is investigated by means of optical microscopy (OM), energy disperse spectroscopy (EDS), scanning electron microscopy (SEM) and X-ray Diffraction (XRD). Micro hardness of weld is tested by micro hardness tester. The results show that the weld joint of dissimilar steel with good quality could be obtained by fiber laser. In the position of 304 fusion zone, d-ferrites are gradually decreased with the increase of welding speed. The microstructures of welding metal close to 304 stainless steel is planar crystal while that close to E36 and welding center are columnar crystal. With the increase of welding speed, the quantity of cellular crystal of welding metal close to 304 stainless steel is increasing and so does cellular crystal of welding center, but there has no significant change in weld microstructure near the E36. Weld zone is mainly consisted by martensites and a small amount of carbides. Microstructural evolution caused by welding speed is not obvious. Composition of welding line zone is well-distributed. However, there is composition gradient on both sides of the fusion zone,which is influenced significantly by welding speed. Lath-shaped martensites ferrites and pearlites are produced on the heat affected zone of E36. The highest hardness value appears on welding center .The hardness of weld zone and E36 heat affected zone is increasing with the increase of welding speed..
Laser & Optoelectronics Progress
- Publication Date: Mar. 26, 2015
- Vol. 52, Issue 4, 41403 (2015)
Research on Electric Derivatives and Reliability of Semiconductor Lasers
Liu Xia, Li Te, Lu Guoguang, and Hao Mingming
For exploring and proving the relationship between semiconductors lasers′ electrical derivatives and their reliability, 12 semiconductor lasers are put in series to electric accelerated aging until the devices do not work. Monitor the variation of semiconductors′ electric derivatives in the process. Then, the figure isFor exploring and proving the relationship between semiconductors lasers′ electrical derivatives and their reliability, 12 semiconductor lasers are put in series to electric accelerated aging until the devices do not work. Monitor the variation of semiconductors′ electric derivatives in the process. Then, the figure is gotten by dealing the experimental data. The experiment finds that the dip of the electric derivative curve at the threshold becomes smaller in the accelerated aging process; The characteristic parameter of junction and the intercept of the electrical derivative above the threshold at I=0 become larger in the accelerated aging process. And the variable of characteristic parameter keeps a small one early. Then, it becomes larger and keeps a large one some time. Finaly, it decreases quickly and keeps a small one. The phenomenon indicates that there are three stages of deterioration of devices: devices deteriorate slowly early, then deteriorate quickly and keep for some time, and devices deteriorate slowly again. There is a close relationship between electric derivatives and lifetime of devices and the deterioration of devices, and electric derivatives can characterize state of semiconductor lasers..
Laser & Optoelectronics Progress
- Publication Date: Mar. 29, 2015
- Vol. 52, Issue 4, 41404 (2015)
Property Degradation of GaAs/Ge Solar Cells after Femtosecond Laser Irradiation
Xue Qing, Wu Wenhui, Ye Yunxia, Liu Haixia, Chen Ruifang, and Hua Yinqun
Effects of femtosecond laser irradiation on GaAs/Ge solar cells are studied. Optical microscope and noncontact optical profilometer are used to measure the surface morphology of the solar cells and the the volt-ampere characteristic test system is used to test the photovoltaic properties. The damage degree of ablation Effects of femtosecond laser irradiation on GaAs/Ge solar cells are studied. Optical microscope and noncontact optical profilometer are used to measure the surface morphology of the solar cells and the the volt-ampere characteristic test system is used to test the photovoltaic properties. The damage degree of ablation on the surface morphology and electrical properties is analysed. The results indicate that when the laser energy density is below 0.53 J/cm2, the damage only reaches the anti-reflection film. With the increase of laser energy density, the damage depth of the solar cell is increasing, when the laser energy density reaches 0.78 J/cm2, the damage gets to the emitter region. With the density increasing, the electric properties such as short circuit current, open circuit voltage, maximum power and filling factor suffer a certain degradation. The decay amplitude of the electric properties increase at first and then decrease. Among all the evaluated electric properties, maximum power degrades most remarkably. In conclusion, laser irradiation could induce a great damage in GaAs/Ge solar cells, which influences the electric properties directly..
Laser & Optoelectronics Progress
- Publication Date: Mar. 26, 2015
- Vol. 52, Issue 4, 41405 (2015)
Mechanism of Femtosecond Laser Ablating CuZr Amorphous Alloy
Chen Bing, Zhu Weihua, Chen Peng, Chen Zhiyong, Guo Wei, and Wang Xinlin
Femtosecond (fs) laser ablating CuZr amorphous alloy is investigated with molecular dynamics (MD) simulation combined with two temperature models. The duration of laser pulse is 200 fs and the fluence is regulated from 30 mJ/cm2 to 45 mJ/cm2. The results indicate that thermal diffusion of CuZr glass metal is much more Femtosecond (fs) laser ablating CuZr amorphous alloy is investigated with molecular dynamics (MD) simulation combined with two temperature models. The duration of laser pulse is 200 fs and the fluence is regulated from 30 mJ/cm2 to 45 mJ/cm2. The results indicate that thermal diffusion of CuZr glass metal is much more slowly as compared with crystalline metal; tensile stresses is observed in target at first;the average size and the number of the gas bubbles generate inside the target are strongly dependent on the laser fluence; photomechanical effects are the main ablation mechanism,and ablation depth increases with fluence. It is helpful to understand the mechanism of interaction between femtosecond laser and amorphous alloy..
Laser & Optoelectronics Progress
- Publication Date: Mar. 26, 2015
- Vol. 52, Issue 4, 41406 (2015)
Materials
Analysis of Mono-Crystalline Silicon Solar Cells Preventing PID Coating Process
Ma Xinjian, Lin Tao, and Feng Shuaichen
Power loss is observed in photovoltaic modules resulting from the potential induced degradation (PID), which is mainly related with packaging glasses, glue film and surface treatment of solar cell. The coating process of solar cell to design the experiment is focused on. Thickness, refractive index, reflectance, minoriPower loss is observed in photovoltaic modules resulting from the potential induced degradation (PID), which is mainly related with packaging glasses, glue film and surface treatment of solar cell. The coating process of solar cell to design the experiment is focused on. Thickness, refractive index, reflectance, minority carrier lifetime of the pre and post coating of silicon nitride (SiNx) anti- reflection coatings of machining standard process and preventing PID process and electrical characteristics of the solar cell are tested and analyzed. The results show that the PID process of mono-crystalline silicon solar cells have good passivation effect, but the anti-reflection effect of the poor is the main cause lead to the low conversion efficiency in the whole spectral range. Electro luminescence defect tests show that the preventing PID process does not bring additional defects to the mono-crystalline silicon solar cell, but solar cells are made by the preventing PID process when it is applied in modules have a resisting potential induced degradation phenomenon and preventing damage to solar cells from metal ion, compared with the standard process..
Laser & Optoelectronics Progress
- Publication Date: Feb. 02, 2015
- Vol. 52, Issue 4, 41601 (2015)
Range Analysis of Thermal Stress and Displacement of GaN films on Al2O3 Substrate
Wang Xiaozeng
A three-dimensional (3D) Ansys model which is comprised of the GaN films and Al2O3 substrate is developed to simulate the thermal stress and displacement from the difference of thermal expansion coefficient between two kinds of materials. The 3D model is used to analyze the thermal stress and displacement in GaN films A three-dimensional (3D) Ansys model which is comprised of the GaN films and Al2O3 substrate is developed to simulate the thermal stress and displacement from the difference of thermal expansion coefficient between two kinds of materials. The 3D model is used to analyze the thermal stress and displacement in GaN films under different deposition temperatures, GaN films thickness, Al2O3 substrate thickness and diameters by the simulating orthogonal test. The influence of the above mentioned factors on the thermal stress and displacement in GaN films is analyzed, and the optimum level combination of factors to minimize the thermal stress and displacement in GaN films is determined. The error between the theoretical and numerical solution of GaN films stress is less than 1.4%. The developed model can be used to analyze the minimum thermal stress and displacement in GaN films. From big to small, the order of the effect of all kinds of factors on the thermal stress in GaN films is the deposition temperature, films thickness, substrate thickness and diameter. The most optimum combination is A1B3C3D1 to minimize the thermal stress. For the displacement in GaN films, the order is the substrate diameter, films thickness, substrate thickness and deposition temperature, and the most optimum combination is A1B3C3D1 for the deposition temperature..
Laser & Optoelectronics Progress
- Publication Date: Mar. 26, 2015
- Vol. 52, Issue 4, 41602 (2015)
Effect of Stress-Induced Anisotropy on Transmittance of One Dimensional Photonic Heterostructures
Peng Jiankun, Wang Hong, Han Yanling, Zhang Xiaohui, and Chen Lei
The 4×4 transfer matrix method is applied to study the transmission and reflection characteristics of one dimensional photonic heterostructures. The key research is the effect of stress-induced anisotropy. The simulation results show that defect-mode in the photonic band gap move distinctly along with the change oThe 4×4 transfer matrix method is applied to study the transmission and reflection characteristics of one dimensional photonic heterostructures. The key research is the effect of stress-induced anisotropy. The simulation results show that defect-mode in the photonic band gap move distinctly along with the change of photonic crystal′s thickness. A linear relationship is presented with the change of the defect-mode′s move and its thickness. The study further explore the stress-induced anisotropy. With different materials, the defect-mode′s displacement is either strengthened or weakened depending on the stress-induced anisotropy. Considering the higher requirement for the precision of sensors, these features of photonic crystal show potential values in the designation and production of pressure sensors..
Laser & Optoelectronics Progress
- Publication Date: Mar. 26, 2015
- Vol. 52, Issue 4, 41603 (2015)
Optical Design and Fabrication
A Optimization Design of Compact Uniform Lens for Large-Size LED
Xu Chao, Gao Shumei, Qian Weiying, Liu Cheng, and Gao Peili
The miniaturization of LEDlamp with high luminous flux and light uniformity is the pursuit of LEDlighting,including commercial and civil lighting.The chips on board (COB)-LEDappeared recent years has high flux.However,special secondary optics still need to generate the required irradiance distribution.For small lightinThe miniaturization of LEDlamp with high luminous flux and light uniformity is the pursuit of LEDlighting,including commercial and civil lighting.The chips on board (COB)-LEDappeared recent years has high flux.However,special secondary optics still need to generate the required irradiance distribution.For small lighting device with compact freeform surface lens on large size COB-LED,a fast optimization design method to achieve the goal of uniform illumination in circular region is proposed.During the optimization,equal arc-length method is applied to reduce the number of optimization points,thus optimization efficiency is enhanced substantially.Combining the cubic spline interpolation and custom merit function,uniform illumination on the target area with light angle at range of 30° to 50° is realized in secondary development environment of TracePro software.The illumination uniformity and light energy utilization rate of the target plane reach more than 90% and 95% respectively.This method is also suitable for the design of uniform lens for COB-LEDpackage ..
Laser & Optoelectronics Progress
- Publication Date: Feb. 10, 2015
- Vol. 52, Issue 4, 42201 (2015)
Research for Fixing and Orientation Structure of Lens
Zhang Limin, and Lü Tianyu
As the mismatch of thermal expansion coefficients between the lens and the frames,stress on the lens is brought under the large temperature range,which can affect the properties of optical system.So a special support structure is designed to minimize the stress.Firstly,several existing form of surface contacted are anaAs the mismatch of thermal expansion coefficients between the lens and the frames,stress on the lens is brought under the large temperature range,which can affect the properties of optical system.So a special support structure is designed to minimize the stress.Firstly,several existing form of surface contacted are analyzed and compared,then the axial and radial effect caused by temperature is calculated,and the fixing and orientation structure is designed prettily.Lastly,the impact of reducing the thermal stress is simulated by the MSC.Patran software.The result indicates that the space and pad for reducing the thermal stress make the stress and deformation of lens caused by temperature decrease clearly,and the rigidity of the assembly system is fine,assembly method simple,as a broad applicable design method can solve the support structure of coaxial optical system..
Laser & Optoelectronics Progress
- Publication Date: Feb. 10, 2015
- Vol. 52, Issue 4, 42202 (2015)
A New PCB Digital Lithograph Projection Imaging Technology
Liu Zhitao, Zhou Jinyun, Liu Lixia, Guo Hua, and Kuang Jian
For meeting the requirements of micron printed circuit board (PCB) lithography, a novel PCB projection imaging digital lithography technology which designs and optimizes the double Gauss type structural lithography projection lens based on ZEMAX optical design software has been proposed. The lens has double telecentricFor meeting the requirements of micron printed circuit board (PCB) lithography, a novel PCB projection imaging digital lithography technology which designs and optimizes the double Gauss type structural lithography projection lens based on ZEMAX optical design software has been proposed. The lens has double telecentric structure and can avoid defocus caused by digital micro- mirror device (DMD) deflection. Its resolution is 13.68 mm, numerical aperture NA is 0.045, depth of focus is 200 mm and image plane distortion is controlled strictly below 0.03%. The lens also uses DMD multi-beam inclined scanning technology, rotating DMD with fixed angle round and forming smaller pixel size by utilizing the position of exposure point and light spot overlap integral energy, which raises mesh precision; since this projection imaging technology is based on lithography experiments proving feasibility of the projection imaging technology, besides integer pixel, the noninteger pixel line width can be obtained and image resolution and production can also be improved by controlling mesh precision..
Laser & Optoelectronics Progress
- Publication Date: Apr. 03, 2015
- Vol. 52, Issue 4, 42203 (2015)
Optical Design of the Adaptive Front Lighting System Based on the LEDand the Fly′s-Eye Lens
Wang Cheng, Zhu Xiangbing, Tian Liwei, Hao Wenliang, and Wang Ruofei
Some limitations are involved in traditional adaptive front lighting system (AFS) such as fewer modes,low control accurateness,low light efficiency and hard heat dissipation,etc.This paper proposes an optical scheme of the AFS based on the LEDand the fly′s- eye lens.Using a fly′s- eye lens,the uniform facula with a cutSome limitations are involved in traditional adaptive front lighting system (AFS) such as fewer modes,low control accurateness,low light efficiency and hard heat dissipation,etc.This paper proposes an optical scheme of the AFS based on the LEDand the fly′s- eye lens.Using a fly′s- eye lens,the uniform facula with a cut-off line can be achieved in the digital micro mirror (DMD).And the compound parabolic concentrator (CPC) and the bent light pipe are used to collect extra light.By controlling the flip position and the flip frequency of the mirrors of the DMD,the passing beam can be achieved.The simulation results show that the average light efficiency of this system is 43.62%.The results of the light distribution can meet the requirements of the ECE R123.In the DMD,59.46% mirrors work and none of the mirrors is in the“OFF”status.Moreover,this system enjoys the features of high light efficiency and less heat dissipation..
Laser & Optoelectronics Progress
- Publication Date: Mar. 18, 2015
- Vol. 52, Issue 4, 42204 (2015)
Optical Devices
Research on the Best Bias Point Automatic Locking Technique for Mach-Zehnder Modulators
Shi Yuewu, Zhou Hui, Nie Xin, Wang Wei, Feng Hanliang, Sun Beiyun, Xiang Hui, Zhu Zhizheng, and Yang Jing
Small signal perturbation method is usually used for the automatic bias control of electro-optic modulator.This method is mainly applied in high speed digital communication,but is not suitable for the transmission of analog signals.An iterative algorithm is proposed,which can lock the best bias point based on closed-loSmall signal perturbation method is usually used for the automatic bias control of electro-optic modulator.This method is mainly applied in high speed digital communication,but is not suitable for the transmission of analog signals.An iterative algorithm is proposed,which can lock the best bias point based on closed-loop control method.The feasibility of this method is analyzed in theory,and the feedback system is built.Experiment is carried out under condition of varying temperature.The result shows that the output power jitter is less than 1.5% as the temperature change rate is less than 5 ℃/min.This method can be used in the transmission of analog signals..
Laser & Optoelectronics Progress
- Publication Date: Feb. 10, 2015
- Vol. 52, Issue 4, 42301 (2015)
Research on Evaluation Method of Optical Imaging Sensors’Photon Response Non-Uniformity Noise
Sun Hui, Xu Shuyan, Sun Shouhong, and Li Junlin
It is proposed that the photon response non- uniformity (PRNU) factor Φ can be used to evaluate photo response non- uniformity noise, which is based on comprehensive analysis of all kinds of optical imaging sensor noise. A test method has been established, and a test platform has also been built with a doubleintegratinIt is proposed that the photon response non- uniformity (PRNU) factor Φ can be used to evaluate photo response non- uniformity noise, which is based on comprehensive analysis of all kinds of optical imaging sensor noise. A test method has been established, and a test platform has also been built with a doubleintegrating sphere structure. Finally, the relationship between the PRNU noise and the incident irradiance is discussed in the whole range of the output values, which has provided a powerful support for the test of other indicators and the correction of photon response non-uniformity..
Laser & Optoelectronics Progress
- Publication Date: Mar. 13, 2015
- Vol. 52, Issue 4, 42302 (2015)
Physical Optics
Prism Group Generating Wide Area Approximate Non-Diffracting Grating Structure Light
Wu Zhiwei
A novel optical system is proposed for generating approximate non-diffracting grating structure light,and it is composed of several triangular-section prisms.The technical problem that the striped regional of approximate non-diffracting grating structure light generating by existing technology is so small that it cannoA novel optical system is proposed for generating approximate non-diffracting grating structure light,and it is composed of several triangular-section prisms.The technical problem that the striped regional of approximate non-diffracting grating structure light generating by existing technology is so small that it cannot be applied to wide range measurement is solved.Physical processes of generating approximate non-diffracting grating structure light is analyzed by interference theory,and relevant parameters are also calculated.The intensity distribution in different positions after system is simulated by Zemax software.The conclusion of simulation is consistent with that of interference theory.And impacts on output beam by several systematic errors are also analyzed.The result shows that when a plane wave illuminates on the novel optical system,approximate nondiffracting grating structure light with wide measurement area,adjustment flexibility and strong anti-interference ability is formed..
Laser & Optoelectronics Progress
- Publication Date: Feb. 10, 2015
- Vol. 52, Issue 4, 42601 (2015)
Bottle Beam Generated by Blue LED
Li Pan, Wu Fengtie, He Xi, and Sun Chuan
A bottle beam is generated using an axicon- lens system and an incoherent blue LED source. It is demonstrated that the bottle beam can be obtained via an axicon-lens system illuminlated by an incoherent source. According to diffraction theory and the superposition of multi-wavelength, the intensity distribution of lighA bottle beam is generated using an axicon- lens system and an incoherent blue LED source. It is demonstrated that the bottle beam can be obtained via an axicon-lens system illuminlated by an incoherent source. According to diffraction theory and the superposition of multi-wavelength, the intensity distribution of light field which is generated by a certain frequency bandwidth of partially coherent light propagating through an axicon-lens system is analyzed. The three-dimensional intensity distribution of the beam evolution and the transverse intensity distributions at different propagating distances are simulated. In the experiment, a blue LED source combined with an axicon-lens system is used to generate the bottle beam. The transverse intensity distribution of the bottle beam is recorded by a stereomicroscope. The experimental results are consistent well with the theoretical analysis, and the result shows a guidance and practical significance for particle trapping and atom cooling..
Laser & Optoelectronics Progress
- Publication Date: Apr. 04, 2015
- Vol. 52, Issue 4, 42602 (2015)
Quantum Optics
Sudden Death and Sudden Birth of Bound Entanglement
Huang Jiang, Xie Qin, Zhou Kaiwei, and Lin Yipeng
The entanglement dynamics of two-qutrits interacted with its independent reservoirs are investigated. The results show that bound entanglement of the two-qutrits transfers to the interaction reservoirs in the evolution process. Due to the conservation of total entanglement information in the whole systems, bound entangThe entanglement dynamics of two-qutrits interacted with its independent reservoirs are investigated. The results show that bound entanglement of the two-qutrits transfers to the interaction reservoirs in the evolution process. Due to the conservation of total entanglement information in the whole systems, bound entanglement sudden death of the atoms must lead to bound entanglement sudden birth of the reservoirs, and the obtained entanglement of the reservoir equals the initial one..
Laser & Optoelectronics Progress
- Publication Date: Feb. 05, 2015
- Vol. 52, Issue 4, 42701 (2015)
Time Evolution of Chaotic Field in Diffusion Process
Lu Daoming
Master equations of density operators in the diffusion process can be concisely solved by the technique of integration within an ordered product of operators and virtue of thermo- entangled state representation. The evolution formula of the field density operator which is chaotic field initially is got. The results shoMaster equations of density operators in the diffusion process can be concisely solved by the technique of integration within an ordered product of operators and virtue of thermo- entangled state representation. The evolution formula of the field density operator which is chaotic field initially is got. The results show that the chaotic field maintains its original properties, but its average number of photons increases linearly in the diffusion process. The photon number fluctuation increases in the form of a quadratic function with diffusion time..
Laser & Optoelectronics Progress
- Publication Date: Feb. 05, 2015
- Vol. 52, Issue 4, 42702 (2015)
Research about Effect of Phase Drift on Phase-Coding QKD System and Intercept-Resend Attack
Jiao Haisong, Wang Yanbo, He Min, Zhu Yong, and Zhang Zhiyong
In consideration of phase drift and intercept-resend (I-R) attack, the quantum key distribution (QKD) system based on double Mach-Zehnder interferometers is analyzed, the model of detectors′ input signal is built, and the formulas are presented to describe the relationship between the phase drift angle and quantum bit In consideration of phase drift and intercept-resend (I-R) attack, the quantum key distribution (QKD) system based on double Mach-Zehnder interferometers is analyzed, the model of detectors′ input signal is built, and the formulas are presented to describe the relationship between the phase drift angle and quantum bit error rate (QBER), as well as the drift angle and eavesdropping information. Meanwhile, a possible method to increase the key generation rate is proposed. Analysis shows that phase drift causes extra errors and damages the system stability. Compared with I-R attack under ideal conditions, eavesdropping information declines, thus the eavesdropping information estimated by privacy amplification could decrease and the final key generation rate would increase. Regardless of the relative phase drift in transmission fiber, QBER varies with phase drift as cosine function, whose period decreases by half under total I-R attack, meaning more sensitive to phase drift. When eavesdropper chooses to attack 55% of all keys, she can gain 25.5% information undiscovered..
Laser & Optoelectronics Progress
- Publication Date: Mar. 03, 2015
- Vol. 52, Issue 4, 42703 (2015)
Remote Sensing and Sensors
Design of Auto-Focus System Based on Digital Image Processing on Overlapped Sections
Wang Zhe, Zhong Haixiu, An Chao, Chen Lingjun, and Wang Hongmin
In aerial remote sensing field, auto-focus is one of the key problems to get high-quality images and applied to the certain fields, but real-time performance is poor. To improve calculating speed, the pixel-by-pixel overlapped sections in the three of frame images are selected as the gist for auto-focus algorithm. The In aerial remote sensing field, auto-focus is one of the key problems to get high-quality images and applied to the certain fields, but real-time performance is poor. To improve calculating speed, the pixel-by-pixel overlapped sections in the three of frame images are selected as the gist for auto-focus algorithm. The auto-focus system consists of charge coupled device (CCD) camera, focusing mechanism, hardware circuit and so on. The new auto-focus algorithm combines captured overlapped areas and estimated similar frame difference method to search overlapped sections. In the overlapped sections, selecting the focusing evaluation function and step length realizes the transition from fast rough adjustment to accurate one and reaches the best state. The design of the software flowchart is given by using the focus value. The real flying experiment demonstrates that the auto-focus system improves the quality of image and the time of respond speed and minishes the burden of image processing software..
Laser & Optoelectronics Progress
- Publication Date: Mar. 24, 2015
- Vol. 52, Issue 4, 42801 (2015)
Detection of Internal Solitary Wave in the South China Sea Using Optical Remote Sensing
Zhang Xudong, Wang Jing, Wei Zizhang, Sun Lina, and Meng Junmin
The generation and propagation of internal wave occurs beneath the sea water, conventional methods such as field observations are restrained by weather conditions as well as other factors, it is difficult for researchers to get enough valid data. Moderate-resolution imaging spectroradiometer (MODIS) become the importanThe generation and propagation of internal wave occurs beneath the sea water, conventional methods such as field observations are restrained by weather conditions as well as other factors, it is difficult for researchers to get enough valid data. Moderate-resolution imaging spectroradiometer (MODIS) become the important research data sources of internal wave because of its large coverage, high temporal resolution, freedom data download, etc. A wide range observation of internal wave is possible with it. Based on data from MODIS, study on internal wave is conducted from June 2010 to June 2012 in South China Sea (0°N~23°N,102°E~121°E). A statistical analysis of temporal and spatial characteristics of internal waves is given. The results show that internal wave generates with a high frequency in the northwestern South China Sea, especially around Dongsha Atoll area which originates from Luzon Strait. In areas around 115°E east to Hainan Island, crest of waves have an obvious distinct characteristics from the waves of Dongsha Atoll, it is possible that there are local generation of internal wave. The temporal distribution of internal wave shows that most of internal waves are observed in summer and observation comes to the least in winter..
Laser & Optoelectronics Progress
- Publication Date: Feb. 14, 2015
- Vol. 52, Issue 4, 42802 (2015)
Reviews
Research Status of Conceptual Design of Diode-Pumped Solid-State Laser Driver for LIFE
Xiao kaibo, Yuan Xiaodong, Jiang Xinying, Yan Xiongwei, Wang Zhenguo, Li Mingzhong, Zheng Jiangang, and Zheng Wanguo
Inertial fusion energy (IFE) is a well-known safe, carbon-free, sustainable and clean energy source. An overview of conceptual design of diode-pumped solid-state laser driver for laser inertial fusion energy (LIFE) project is presented while some emphases are given on laser system requirements, laser architecture and sInertial fusion energy (IFE) is a well-known safe, carbon-free, sustainable and clean energy source. An overview of conceptual design of diode-pumped solid-state laser driver for laser inertial fusion energy (LIFE) project is presented while some emphases are given on laser system requirements, laser architecture and some key technical units. Among those, the laser architecture consisting of optical layout, amplifier architecture, gain medium and system efficiency, and diode laser pump source are introduced in detail. Key technical units, such as thermal birefringence and depolarization compensation, cylindrical spatial filter concept, are also summarized. The development of LIFE project has an important effect on high average power laser technology, high power diode and laser material..
Laser & Optoelectronics Progress
- Publication Date: Apr. 04, 2015
- Vol. 52, Issue 4, 40001 (2015)
Application and Development Prospects of Optical Micro-resonators
Zhang Ying, Chen Meixiong, Li Yingying, and Yuan Jie
With the continuous development of laser technology, optical micro-resonator with high Q-value attracts more and more attentions. Apart from broad applications in traditional optics, it also has a considerable prospect in quantum information and quantum integrated chips. Two kinds of micro-resonators are introduced, whWith the continuous development of laser technology, optical micro-resonator with high Q-value attracts more and more attentions. Apart from broad applications in traditional optics, it also has a considerable prospect in quantum information and quantum integrated chips. Two kinds of micro-resonators are introduced, which are whispering gallery mode and photonic crystal optical micro-resonators. Their principle, history and advantages compared with traditional optical cavity are analyzed in detail. Meanwhile, the mode distribution of different structures of optical micro-resonators are simulated. Based on the unique advantages, the applications of whispering gallery mode optical micro-resonators are introduced in the area of laser, biological detection and quantum physics. And the considerable prospect of photonic crystal optical micro-resonators is predicted in the area of integrated optics and microelectronic technology..
Laser & Optoelectronics Progress
- Publication Date: Mar. 26, 2015
- Vol. 52, Issue 4, 40002 (2015)
Research Progress of Stimulated Brillouin Scattering Suppression in Narrow Linewidth Fiber Amplifiers
Ran Yang, Wang Xiaolin, Su Rongtao, Zhou Pu, and Si Lei
Stimulated Brillouin scattering(SBS) is the main factor which limits the output power in narrow linewidth high power fiber amplifiers. Present SBS suppression methods and progress at home and abroad are illustrated, phase modulation to broaden the linewidth of the seed laser and the methods through applying gradient ofStimulated Brillouin scattering(SBS) is the main factor which limits the output power in narrow linewidth high power fiber amplifiers. Present SBS suppression methods and progress at home and abroad are illustrated, phase modulation to broaden the linewidth of the seed laser and the methods through applying gradient of temperature and strain to broaden the SBS gain spectrum are emphatically introduced, as well as some other methods such as acoustically tailored fiber. Finally, different approaches of SBS suppression are summarized and compared, which provides some references in related studies..
Laser & Optoelectronics Progress
- Publication Date: Apr. 04, 2015
- Vol. 52, Issue 4, 40003 (2015)
Research Progress in Optical Spacing Measurement Technology
Shi Zhonghua, Yang Baoxi, Wei Zhangfan, Li Jing, and Huang Huijie
As the most basic optical element in the optical system,the center thickness machining precision and assembly precision of the lens directly affect the imaging quality of the optical system.Kinds of non-contact measuring methods that have been proposed in recent years are introduced.The working principles and developinAs the most basic optical element in the optical system,the center thickness machining precision and assembly precision of the lens directly affect the imaging quality of the optical system.Kinds of non-contact measuring methods that have been proposed in recent years are introduced.The working principles and developing trends of the imaging method,axial dispersion measuring method,differential confocal measuring method,low coherence interferometry measuring method are described,as well as their own advantages and disadvantages.These methods can satisfy the precision requirement of the optical system,and the low coherence interferometry method provides the highest precision.The axial dispersion method and the confocal method comes second,and the imaging method is the last one.The developing direction of the lens gap measurement technology is discussed..
Laser & Optoelectronics Progress
- Publication Date: Feb. 10, 2015
- Vol. 52, Issue 4, 40004 (2015)
Spectroscopy
Spectroscopic Method for Measuring Electron Temperature and Electron Density of Thermal Spray Plasma
Sun Chengqi, Gao Yang, Yang Deming, and He Kun
Emission spectroscopy is an important method for plasma diagnostics. The intensity ratio of spectrum lines at 763.51 nm and 772.42 nm is used to estimate the electron excited temperature of the thermal plasma jet under the low pressure plasma spray. Impact of different power levels and detection distance on the electroEmission spectroscopy is an important method for plasma diagnostics. The intensity ratio of spectrum lines at 763.51 nm and 772.42 nm is used to estimate the electron excited temperature of the thermal plasma jet under the low pressure plasma spray. Impact of different power levels and detection distance on the electron temperature in the thermal spray plasma jet under Ar/H2 flow rate of 40 L/min/15 L/min is investigated. Electron number density of the plasma jet is determined using stark broadening of Hβ , impact of changes of the detection distance is also studied. An increase in input power considerably increases the electron temperature, while it is found that electron temperature decreases with detection distance from nozzle exit increasing from 150 mm to 450 mm, and the increase of detection distance from l00 mm can remarkably reduce the electron number density. After that, there is little change of electron number density..
Laser & Optoelectronics Progress
- Publication Date: Mar. 24, 2015
- Vol. 52, Issue 4, 43001 (2015)
A Processing Method for Spectral Data of Online Total Phosphorus Detection in Water
Wang Bin, and Yang Huizhong
In the online detection of total phosphorus for water quality, due to the limitation of measuring accuracy of micro-spectrometer and some external interference, the stability of spectral data is damaged so that the detection stability and precision is affected. Kalman filter and non-linear regression method are used toIn the online detection of total phosphorus for water quality, due to the limitation of measuring accuracy of micro-spectrometer and some external interference, the stability of spectral data is damaged so that the detection stability and precision is affected. Kalman filter and non-linear regression method are used to deal with spectral data on the basis of ultraviolet spectrophotometry, and then the relationship equation between absorbance and concentration is established. Thus the content of total phosphorus can be calculated. The method can improve the stability and precision of online detection. The problem of stochastic disturbance and system error can be solved very well. It can be used for real-time monitoring of total phosphorus..
Laser & Optoelectronics Progress
- Publication Date: Mar. 24, 2015
- Vol. 52, Issue 4, 43002 (2015)
Qualitative Analysis Model of Near Infrared Spectra of Pork Based on Synergy Interval Partial Least Squares Discriminant Analysis
Wu Xiaohong, Sun Jun, Wu Bin, and Tang Kai
To solve the problems of noise and redundancy in spectra regions which partial least squares discriminant analysis (PLSDA) encounters, synergy interval partial least squares discriminant analysis (SiPLSDA) is proposed and is used in the qualitative analysis model of near infrared spectra of pork. With the help of synerTo solve the problems of noise and redundancy in spectra regions which partial least squares discriminant analysis (PLSDA) encounters, synergy interval partial least squares discriminant analysis (SiPLSDA) is proposed and is used in the qualitative analysis model of near infrared spectra of pork. With the help of synergy interval partial least squares (SiPLS), SiPLSDA can select the spectral regions where the prediction model is constructed. Antaris II Fourier transform-near infrared (FT-NIR) spectrophotometer is used to obtain near infrared reflectance (NIR) spectra of pork samples in the range of 10000~4000 cm- 1. NIR spectra are preprocessed by standard normal variate (SNV) transformation. A qualitative analysis model of NIR spectra is built by SiPLSDA. The experimental results show that according to the SiPLSDA prediction model, the recognition ratio of pork storage time is up to 93.94 % and it is higher than that of PLSDA..
Laser & Optoelectronics Progress
- Publication Date: Mar. 26, 2015
- Vol. 52, Issue 4, 43003 (2015)
Terahertz Time Domain Spectroscopy of Different Kinds of Water
Lu Chengzhen, Liu Wei, Sun Ping, Wang Yixin, and Jiang Zhaofeng
Terahertz (THz) detection is a novel and very effective coherent detection method,and both abundant amplitude information and ample phase information of materials which need to be detected and consequently contrast can be achieved.The THz spectral properties of several kinds of water are investigated based on the terahTerahertz (THz) detection is a novel and very effective coherent detection method,and both abundant amplitude information and ample phase information of materials which need to be detected and consequently contrast can be achieved.The THz spectral properties of several kinds of water are investigated based on the terahertz time domain spectroscopy (THZ-TDS) system.A sort of iterative approach is given,in order to avoid the result error caused by weak absorption approximation,which improves the traditional methods of data processing of transmission spectroscopy of terahertz time-domain.Compared with different filters,Symlets9 wavelet filter is considered to be optimal filter.The exponential change laws of refractive index and absorption coefficient with frequency are gotten with square of correlation coefficient up to 0.9 upwards.The results indicate that both square of correlation coefficient and fitting curve parameters of different kinds of water are different,which can be defined as the criteria to distinguish water quality..
Laser & Optoelectronics Progress
- Publication Date: Mar. 18, 2015
- Vol. 52, Issue 4, 43004 (2015)
X-Ray Optics
Micro-X-Ray Fluorescence Analysis of Colored pigments Containing Au on the Ancient Bowl of Qing Dynasty
Cheng Lin, Li Meitian, Wang Junling, Duan Zeming, Li Rongwu, and Pan Qiuli
Study of the chemical compositions and fired technologies of ancient colored glaze of Qing dynasty official kiln is very poor. Chemical compositions and elemental mappings of Au glaze bowl of Qing dynasty are studied by micro-X-ray fluorescence analysis. The results show that Cu,Fe,Mn, Au are the mainly colored elementStudy of the chemical compositions and fired technologies of ancient colored glaze of Qing dynasty official kiln is very poor. Chemical compositions and elemental mappings of Au glaze bowl of Qing dynasty are studied by micro-X-ray fluorescence analysis. The results show that Cu,Fe,Mn, Au are the mainly colored elements and Pb is a kind of solvent. Moreover, the red glaze of bowl is a kind of high temperature glaze, but the golden, light yellow and green glazes are the kind of low temperature glazes. The elemental mappings show that the eyes of goldfish are painted by colored pigment mixed by Cu, Au, Fe, Pb, the whole body of goldfish is painted by a kind of pigment mixed by Pb and Fe, but the scales of goldfish are painted by colored pigment mixed by Au and Pb. Furthermore, the grades of purity of different colored pigments are very high and no other metallic elements except that the colored elements are detected in our experiment. This can be regarded as the reference to authenticating the genuineness of the color pigments of Qing dynasty..
Laser & Optoelectronics Progress
- Publication Date: Apr. 04, 2015
- Vol. 52, Issue 4, 43401 (2015)
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