Journals >Laser & Optoelectronics Progress
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2014
Volume: 51 Issue 5
32 Article(s)
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Fiber Optics and Optical Communications
Optimal Selection of Receiving Optical Power in Laser Communication System in Atmospheric Turbulence
Gao Duorui, Fu Qiang, and Zhao Zhao
Taking partially coherent Gaussian- Schell model (GSM) beam as an example to get the best launch parameters of laser communication system, considering overall decline of the alignment adaption loss caused by beam drift and decrease of receiving optical power density induced by beam expanding, some numerical calculationTaking partially coherent Gaussian- Schell model (GSM) beam as an example to get the best launch parameters of laser communication system, considering overall decline of the alignment adaption loss caused by beam drift and decrease of receiving optical power density induced by beam expanding, some numerical calculation and analysis on the receiving power in the laser link are necessary. Results represent that in atmospheric turbulence the best launch parameters of laser communication system are related to beam waist radius, spatial coherent length, wavelength, propagation distance and turbulence intensity. There exists an optimal value when the receiving power density of the partially coherent GSM beam changes with the variance of the wavelength, beam width, degree of coherence and transmission distance..
Laser & Optoelectronics Progress
- Publication Date: Mar. 21, 2014
- Vol. 51, Issue 5, 50601 (2014)
Temperature Monitoring for Concentrated Photovoltaic Power System Based on Optical Fiber Temperature Sensor
Liao Tianjun, Lin Bihong, and Yang Zhimin
For the problem that energy conversion efficiency and lifespan of concentrated photovoltaic solar cells are greatly influenced by temperature, a method of monitoring and controlling the temperature of the concentrated photovoltaic power system based on the GaAs semiconductor absorption optical fiber temperature sensor For the problem that energy conversion efficiency and lifespan of concentrated photovoltaic solar cells are greatly influenced by temperature, a method of monitoring and controlling the temperature of the concentrated photovoltaic power system based on the GaAs semiconductor absorption optical fiber temperature sensor is proposed. The results of numerical simulation experiment show that when the flow rate of the cooling water is reduced, higher temperature of the concentrated photovoltaic cells could be detected by the optical fiber temperature detection system. Then we can reduce the temperature of the concentrated photovoltaic cells through improving the flow rate of the cooling water. With prolonging the life of concentrator photovoltaic cells and improving the utilization rate of solar energy, the proposed method has a certain theoretical significance..
Laser & Optoelectronics Progress
- Publication Date: Mar. 28, 2014
- Vol. 51, Issue 5, 50602 (2014)
Study of Seawater Salinity Sensor Based on Embedded Microfiber Ring Resonator
Li Guoxiang, Wang Shanshan, Yang Hongjuan, and Wang Jing
A new seawater salinity sensor is designed for salinity measurement by embedding the Loop resonator in MgF2 which has a positive thermo- optic coefficient. The model of seawater salinity sensor is established by COMSOL software and combining with Matlab, and characteristic parameters of the sensor are studied. The resuA new seawater salinity sensor is designed for salinity measurement by embedding the Loop resonator in MgF2 which has a positive thermo- optic coefficient. The model of seawater salinity sensor is established by COMSOL software and combining with Matlab, and characteristic parameters of the sensor are studied. The results show that the temperature characteristic of embedded ring resonator sensor depends on the microfiber radius, and the size of microfiber for weak temperature dependence decreases with the decrease of wavelength. Higher sensitivity corresponds to smaller coating thickness and smaller microfiber radius. Detection limit increases with the increase of coating thickness and decreases with the decrease of wavelength. By optimizing the parameters of the sensor, sensitivity and detection limit can reach 0.025 nm/(mg/mL) and 0.15 mg/mL, respectively..
Laser & Optoelectronics Progress
- Publication Date: Mar. 28, 2014
- Vol. 51, Issue 5, 50603 (2014)
Study of the Effects of Third-Order Dispersion in Ultra-High Speed Optical Fiber Communication System
Yu Zhenhong, and Xie Fengfeng
We analyze pulse distortions due to the third- order dispersion (TOD) in ultra- high- speed optical fiber communication by using OptiSystem software. The effects of TOD are observed considering the variation of different factors such as bit rate, duty cycle, pulse shape and fiber type when pulse signals are transmittedWe analyze pulse distortions due to the third- order dispersion (TOD) in ultra- high- speed optical fiber communication by using OptiSystem software. The effects of TOD are observed considering the variation of different factors such as bit rate, duty cycle, pulse shape and fiber type when pulse signals are transmitted through optical fiber communication system at a transmission distance of 2000 km. Meanwhile, we find that Qfactor of Gaussian pulses is better than that of super-Gaussian pulses at a transmission distance of 2000 km. The simulation results show that the performance of a standard single- mode fiber chirped fiber Bragg grating (SSMF-CFBG) system is better in ultra-high-speed application when both group velocity dispersion (GVD) and TOD effects are considered..
Laser & Optoelectronics Progress
- Publication Date: Apr. 30, 2014
- Vol. 51, Issue 5, 50604 (2014)
All-Fiber Mach-Zehnder Temperature Sensor Based on Inter-Modal Interference
Lü Weiwei, Xu Feng, and Yu Benli
An all-fiber Mach-Zehnder interferometer (MZI) temperature sensor based on the inter-modal interference principle is proposed and experimentally demonstrated. According to the simulation results of the MZI based on core-offset, we optimized the structural parameters of such an MZI sensor. The MZI sensor based on core-oAn all-fiber Mach-Zehnder interferometer (MZI) temperature sensor based on the inter-modal interference principle is proposed and experimentally demonstrated. According to the simulation results of the MZI based on core-offset, we optimized the structural parameters of such an MZI sensor. The MZI sensor based on core-offset with the extinction ratio of more than 20 dB is obtained successfully. The performance of sensing temperature of such MZI sensors is tested. The influence of the interference length and bending structure of such MZI sensors on the temperature response are also investigated in detail. The temperature sensitivity is improved and reaches to 116 pm/°C..
Laser & Optoelectronics Progress
- Publication Date: Mar. 21, 2014
- Vol. 51, Issue 5, 50605 (2014)
Polymer Micro-Cavity Based Probe Type Fiber Fabry-Perot Interferometer Sensor
Yang Xianhui, Zhang Xuanyu, Wan Zhitao, Liu Zhenling, Yang Hao, and Yu Yongsen
A polymer micro-cavity based probe-type fiber Fabry-Perot interferometer is demonstrated by coating PDMS at the end tip of the single mode fiber, at the same time, the refractive index (RI) and temperature sensing characteristics of the sensor are also investigated. The refractive index and temperature sensing are baseA polymer micro-cavity based probe-type fiber Fabry-Perot interferometer is demonstrated by coating PDMS at the end tip of the single mode fiber, at the same time, the refractive index (RI) and temperature sensing characteristics of the sensor are also investigated. The refractive index and temperature sensing are based on extinction ratio measurement and wavelength shift measurement, respectively. Meanwhile, the theoretical analysis of the special refractive index sensing characteristics of the sensor is conducted, which can be used to design sensors. The sensor has a simultaneously high sensitivity to refractive index and temperature, the refractive index sensitivity is -180.359 dB/RIU (RI unit) in the refractive index range of 1.3625～1.4206, and the temperature sensitivity is 355.28 pm/℃ in the temperature range of 25 ℃～60 ℃. The sensor has the merits of compact size and good biocompatibility. It is advantageous in applications for biochemical activity detection when compared to the conventional fiber sensors, such as tissue culture..
Laser & Optoelectronics Progress
- Publication Date: Apr. 29, 2014
- Vol. 51, Issue 5, 50606 (2014)
Holography
Method of Making Large-Scale 3D Portrait Fresnel Hologram
Nie Yaru, Liu Huiping, Yu Jia, Wang Jincheng, and Yang Yu
A holographic method for displaying large-scale three-dimensional (3D) portrait is put forward. The method is based on the theory of Fresnel hologram and holographic stereogram, resolving the problem that the reconstruction window does not accord with observation field-of-view. Using laser as a recording and reconstrucA holographic method for displaying large-scale three-dimensional (3D) portrait is put forward. The method is based on the theory of Fresnel hologram and holographic stereogram, resolving the problem that the reconstruction window does not accord with observation field-of-view. Using laser as a recording and reconstruction source, the hologram experiment is carried out. By this method, 3D portrait hologram with a large scale and large depth-of-field is made, which can be reconstructed by laser..
Laser & Optoelectronics Progress
- Publication Date: Mar. 28, 2014
- Vol. 51, Issue 5, 50901 (2014)
Imaging Systems
Deflection Tomography Reconstruction Technology Based on Deflection Angle Compressed Sensing Revision from Few View-angles Projections
Zhang Bin, and Liu Long
The theory of compressed sensing is integrated with deflection angle revision iteration technique for deflection tomography reconstruction from few view- angles projections. A new iterative reconstruction algorithm with deflection angle compressed sensing revision is developed to improve the quality of reconstruction dThe theory of compressed sensing is integrated with deflection angle revision iteration technique for deflection tomography reconstruction from few view- angles projections. A new iterative reconstruction algorithm with deflection angle compressed sensing revision is developed to improve the quality of reconstruction distribution from incomplete projection data. The algorithm, which combines the sparsity of the object field gradient l1 norm, is adjusted by total variation with the steepest descent method. A compressed sensing weighting factor is employed in every iteration step to optimize the reconstruction. In numerical simulation, the new approach produces reliable reconstruction for asymmetrical temperature distribution from 6 view- angles projections. The error analysis provides a good indication of the precision and convergence of the algorithm. Compared with our previous algorithm for deflection tomography, the new algorithm turns out to be more accurate.The maximum value error is reduced by 18.32% and the normalized distance error is reduced by 46.67% when the new reconstruction algorithm is employed. The efficacy of the new algorithm has been assessed by reconstructing a flame temperature field..
Laser & Optoelectronics Progress
- Publication Date: Apr. 15, 2014
- Vol. 51, Issue 5, 51102 (2014)
Application of Digital Micromirror Device in Photoelectric Equipment
Xu Zhengping
Considering the super spatial-light-modulation feature, the application and related technologies of digital micromirror device (DMD) in photoelectric equipments are analyzed in detail. Based on analyzing the relationship between maximum frame frequency that could be realized，systemic architecture, gray-scale level and Considering the super spatial-light-modulation feature, the application and related technologies of digital micromirror device (DMD) in photoelectric equipments are analyzed in detail. Based on analyzing the relationship between maximum frame frequency that could be realized，systemic architecture, gray-scale level and the type of DMD, the project with several DMDs in series to achieve high gray-scale level is given. The realizations of DMD′s spatial modulation feature used to enhance system performance are discussed. DMD can be used for high dynamic range imaging, intra-pixel target feature detection, superresolution of detector pixel, compressive sensing and imaging spectrometer. Also, the key technologies in the application are given, including time of exposure determination for every pixel in high dynamic range imaging, geometrical alignment between micromirror in DMD and detector pixel, relative motion between target and detector on motorial platform and the effect of DMD micromirror fill factor on system performance. The programming imaging system with DMD, which allows greater control over the orientations of individual mirrors and has higher updating frequency of memory, is regarded as the new trend..
Laser & Optoelectronics Progress
- Publication Date: Apr. 15, 2014
- Vol. 51, Issue 5, 51103 (2014)
Instrumentation, Measurement and Metrology
Absolute Rotation Measurement for Space-Domain Raman Pulses Cold Atom Gyroscope
Zou Pengfei, Yan Shuhua, and Lin Cunbao
The fundamental principle of cold atom interferometer is analyzed using a novel diagrammatic approach, and the theoretical modeling of space- domain Raman pulses cold atom gyroscope is created. Through the manipulation of approximate mathematical model of the cold atom interferometer, the relationship between the velocThe fundamental principle of cold atom interferometer is analyzed using a novel diagrammatic approach, and the theoretical modeling of space- domain Raman pulses cold atom gyroscope is created. Through the manipulation of approximate mathematical model of the cold atom interferometer, the relationship between the velocity and the transition probability of atom is studied to expound the atom′ s velocity scanning method based on assistant angular velocity sensor. In consideration of precise theoretical modeling, the Raman frequency modulation is used to restrain the Doppler effect and the phase modulation is used to fix the phase relationship in atom′ s velocity scanning method. The numerical simulation calculation results show that the method with compensation and correction can realize rotation measurement with high- precision within the measurement range of the assistant angular velocity sensor..
Laser & Optoelectronics Progress
- Publication Date: Apr. 29, 2014
- Vol. 51, Issue 5, 51201 (2014)
A Method to Modify Systematic Errors in the Stitching
Zhou You, Wang Qing, and Liu Shijie
This paper describes a method that can correct systematic errors in the subaperture stitching measurement after analyzing the absolute test of three-flat testing. The testing gets a vertical profile of data and horizontal profile of data along the diameter of the reference flat, and then using the data to fit an error This paper describes a method that can correct systematic errors in the subaperture stitching measurement after analyzing the absolute test of three-flat testing. The testing gets a vertical profile of data and horizontal profile of data along the diameter of the reference flat, and then using the data to fit an error correction wavefront of the reference flat, namely the use of Zernike polynomials (defocus and ast) for lowlevel fitting. Experiments show that this method can eliminate the systematic errors caused by the interferometer reference flat, and effectively improve the accuracy of wavefront stitching..
Laser & Optoelectronics Progress
- Publication Date: Apr. 04, 2014
- Vol. 51, Issue 5, 51202 (2014)
High Precise Absolute Flat Calibration
Miao Erlong, Su Dongqi, and Peng Shijun
Absolute calibration is an important method to improve accuracy in high precise surface figure testing. But for flat absolute calibration, the power of the flat cannot be calibrated in both the classic three-flat and the rotation- shifting absolute calibration. Using liquid surface absolute calibration can give flat suAbsolute calibration is an important method to improve accuracy in high precise surface figure testing. But for flat absolute calibration, the power of the flat cannot be calibrated in both the classic three-flat and the rotation- shifting absolute calibration. Using liquid surface absolute calibration can give flat surface figure including the power term, but the liquid surface is easily affected by environments and the repeatability is not good enough to get high accurate results. In order to solve the problem, liquid surface is used only to calibrate the power term and the other Zernike terms are calibrated by the rotation - shifting method. By this way, all the Zernike terms of the flat are absolutely calibrated and the test accuracy of the interferometer is greatly improved..
Laser & Optoelectronics Progress
- Publication Date: Apr. 30, 2014
- Vol. 51, Issue 5, 51203 (2014)
Lasers and Laser Optics
Reliability Evaluation of Space Irradiated Laser Diode in Laser Satellite Communication System
Liu Yun, Zhao Shanghong, Yang Shengsheng, Li Yongjun, and Qiang ruoxin
Laser diode is the preferred laser source for satellite laser communication system, and it is significant to analyze its reliability in space radiation environment. According to the character of space radiation and devices′ radiation dose, normal distribution is used to describe both space radiation dose rate and perfoLaser diode is the preferred laser source for satellite laser communication system, and it is significant to analyze its reliability in space radiation environment. According to the character of space radiation and devices′ radiation dose, normal distribution is used to describe both space radiation dose rate and performance degradation per unit radiation dose, and the reliability function of laser diode is achieved. The performance degradation in high- orbit radiation environment is simulated. On the basis of the simulated data, devices′ distribution function is evaluated by maximum likelihood estimate, and then the reliability curve and average life are obtained. The feasibility of using less experimental time and less sample number to evaluate distribution function is analyzed..
Laser & Optoelectronics Progress
- Publication Date: Apr. 29, 2014
- Vol. 51, Issue 5, 51401 (2014)
Effect of Shielding Gas on Laser Welding of Austenitic Stainless Steel
Liu Jian, Shi Yan, Liu Jia, and Zhang Hong
In order to study the effect of shielding gas on mechanical properties of austenitic stainless steel welding joint, a comparison between weld with shielding gas and weld with no shielding gas in the same line energy is studied. Austenitic stainless steel in 0.7 mm thick is welded by using Nd:YAG laser, the microstructuIn order to study the effect of shielding gas on mechanical properties of austenitic stainless steel welding joint, a comparison between weld with shielding gas and weld with no shielding gas in the same line energy is studied. Austenitic stainless steel in 0.7 mm thick is welded by using Nd:YAG laser, the microstructure and mechanical properties of the welding joint are analyzed by means of scanning electron microscope (SEM), micro- hardness tester and material testing machine. Results show that two types of welding both achieve full penetration, and have good weld- forming in the same laser processing parameters. When welding with no shielding gas, with the decrease of welding speed, the tensile strength of welded joints also decrease. The decrease rate reaches 20% at most. After adding shielding gas, the tensile strength of welded joints changes smoothly, all tensile strength are over 90% of matrix..
Laser & Optoelectronics Progress
- Publication Date: Mar. 28, 2014
- Vol. 51, Issue 5, 51402 (2014)
A Continuous-Wave c-Cut Tm,Ho:YAP Laser with 10.5 W Output Pumped by a Laser Diode
Li Linjun, Yang Xining, Bai Yunfeng, and Zhang Zhiguo
A high power and efficiency continuous-wave 2044 nm c-cut Tm,Ho:YAP laser is designed and fabricated. Based on a dual-end pumped scheme, a c-cut Tm,Ho:YAP crystal is pumped by a laser diode with centre wavelength of 794.75 nm, the dimensions of crystal is 4 mm × 4 mm × 7 mm, its co-doped atomic fraction are 5A high power and efficiency continuous-wave 2044 nm c-cut Tm,Ho:YAP laser is designed and fabricated. Based on a dual-end pumped scheme, a c-cut Tm,Ho:YAP crystal is pumped by a laser diode with centre wavelength of 794.75 nm, the dimensions of crystal is 4 mm × 4 mm × 7 mm, its co-doped atomic fraction are 5% Tm and 0.3% Ho，and the laser crystal is cooled by liquid N2. The end faces of laser crystal polished plane are both coated by 790~800 nm and 1900~2100 nm with reflectivity less than 0.5% . The resonator cavity of c-cut Tm,Ho:YAP is a plano-concave cavity with a plano-concave mirror and a flat mirror, and its physical cavity length is 150 mm. The different pumped wavelengths are changed by altering the temperature of laser diode in experiment, a measured maximum output power of 10.5 W is achieved with an optical-optical conversion efficiency of 37.4%..
Laser & Optoelectronics Progress
- Publication Date: Mar. 21, 2014
- Vol. 51, Issue 5, 51403 (2014)
Experimental Investigation on Laser Transmission Welding of Thermoplastic
Sekou Singare, Chen Shengui, and Lin Yongzhou
The effect of the laser welding parameters such as laser power, welding speed on weld strength and microstructure is investigated. A 300 W YAG laser with wavelength of 1064 nm is used to weld the transparent and absorbing polycarbonate (PC) in a lap weld configuration. The force at break of the lap welds is assessed onThe effect of the laser welding parameters such as laser power, welding speed on weld strength and microstructure is investigated. A 300 W YAG laser with wavelength of 1064 nm is used to weld the transparent and absorbing polycarbonate (PC) in a lap weld configuration. The force at break of the lap welds is assessed on the universal testing machine. The weld fracture surfaces and weld cross-sections are visualized using polarized light microscopy to qualitatively assess the weld quality. The result shows that for transparent PC plastic thickness between 1 mm and 3.5 mm, the transmittance does not change significantly and the part thickness usually has little influence on transmittance. The weld strength shows a clear increase with the line energy increasing. The weld strength reaches a maximum when the line energy raises to about 1 J/mm and then starts to fall off. A peak tensile strength of 1.3 kN is obtained with transparent part thickness of 3.5 mm, laser power of 40 W and welding speed of 40 mm/s. It is concluded that in laser welding of thermoplastic material, the heat input should be strictly controlled to improve the welding strength..
Laser & Optoelectronics Progress
- Publication Date: Apr. 29, 2014
- Vol. 51, Issue 5, 51404 (2014)
Research on Thermal Performance for Resonator of Mechanically Dithered Ring Laser Gyroscopes
Lan Peifeng, Liu Yuanzheng, Wang Jiliang, and Xu Hongcai
Thermal deformation and stress have an important influence on performance of ring laser gyroscopes (RLG) in high-low temperature. The traditional design methods of RLG are focus on optical performance of resonator more than mechanical and thermal performance. Generally, the traditional structural design of resonator isThermal deformation and stress have an important influence on performance of ring laser gyroscopes (RLG) in high-low temperature. The traditional design methods of RLG are focus on optical performance of resonator more than mechanical and thermal performance. Generally, the traditional structural design of resonator is dependent on experienced equation and experiment, which result in more iterative design and lower efficiency. Relationship between thermal performance and structural parameters is studied by finite element (FE) method in resonator of mechanically dithered ring laser gyroscopes, the temperature field of resonator and relationship between thermal performance and structural parameters are obtained, which provide the resonator of mechanically dithered ring laser gyroscopes with significant and directive method. It has significance to improve efficiency, shorten hour and reduce cost..
Laser & Optoelectronics Progress
- Publication Date: Mar. 28, 2014
- Vol. 51, Issue 5, 51405 (2014)
Optical Design and Fabrication
Design for Free-Form Reflector Surface Based on Foci Mapping Ellipse Flow-Line Methods and Gradient Optimization
Zhang Hang, Li Meihua, Ma Yufei, Liang Xue, and Yan Jinhua
An optimized design method of free-form reflector surface for extended LED source, which is based on the foci mapping ellipse flow- line methods for generating free- form surfaces and the gradient operator for optimization, is presented. And a continued free- form surface reflecting the lights from a 5 mm size LED exteAn optimized design method of free-form reflector surface for extended LED source, which is based on the foci mapping ellipse flow- line methods for generating free- form surfaces and the gradient operator for optimization, is presented. And a continued free- form surface reflecting the lights from a 5 mm size LED extended source to a target plane in rotational symmetrical uniform pattern is designed and optimized. Optical simulation results show that the original irradiance uniformity is about 0.77 and the optimized irradiance uniformity reaches 0.98. This method can be applied to the optical design of non-rotational symmetric reflector..
Laser & Optoelectronics Progress
- Publication Date: Apr. 10, 2014
- Vol. 51, Issue 5, 52201 (2014)
Optical System Design of High-Precision Static Star Simulator with Large Field of View
Chen Qimeng, Zhang Guoyu, Wang Zhe, and Zhang Jian
In order to complete the calibration work of the star sensor, a high- precision collimating optical system with large field of view is designed. According to the static star simulator′ s working principle about cohesion between exit pupil of star simulator and entrance pupil of star sensor, the design principle and parIn order to complete the calibration work of the star sensor, a high- precision collimating optical system with large field of view is designed. According to the static star simulator′ s working principle about cohesion between exit pupil of star simulator and entrance pupil of star sensor, the design principle and parameters of optical system is determined. The design results show that the field of view is Φ39°, distortion is less than 0.1% . A method of making star point board in accordance with aberrations of the optical system is put forward, to avoid process of repeatedly engraving star point board. Finally, the design of the system is tested. According to the testing results: simulated accuracy of the whole system reaches 15″ , the data can meet the using requirement of high accuracy with large field static star simulator..
Laser & Optoelectronics Progress
- Publication Date: Apr. 09, 2014
- Vol. 51, Issue 5, 52202 (2014)
Stray Light Suppression of the Large Field of View Coronagraph Optical System
Sun Mingzhe, hang Hongxin, Lu Zhenwu, Bu Heyang, Ma Junlin, and Wang Xiaoxun
The large field of view coronagraph is used to image the corona within 215 solar radii. This coronagraph can be used to monitor the solar activity and forecast the violent space weather events. For the need of the stray light suppression, the coronagraph is designed to be an external occulted and secondary imaging systThe large field of view coronagraph is used to image the corona within 215 solar radii. This coronagraph can be used to monitor the solar activity and forecast the violent space weather events. For the need of the stray light suppression, the coronagraph is designed to be an external occulted and secondary imaging system. The optical system has a length of 355.89 mm, a field of view of ± 20° and a focal length of 40 mm. The stray light of the coronagraph is divided into three levels by the intensity. The first level is the direct light from the sun. The second level is the diffracted light from the occulter and external diaphragm. The third level is the reflected light from the inner occulter, the diffracted light from the objective aperture and the scatted light. The three levels of stray light are suppressed respectively. Finally, the stray light level of the coronagraph is 10-9 at the inner field and 10-13 at the outer field..
Laser & Optoelectronics Progress
- Publication Date: Apr. 29, 2014
- Vol. 51, Issue 5, 52203 (2014)
New Design of Collimating Lens Based on LED Light Source
Bai Ying, Xie Guoqing, Lin Wenshuo, and Zhong Yong
By combining the compound paraboloid with free-form surfaces，a small, energy-efficient collimating lens based on LED light source is designed. The optical design is carried on in two parts separately. One part of the light, whose divergence angle between 0o and 20o, is collimated through a spherical cap contracted the By combining the compound paraboloid with free-form surfaces，a small, energy-efficient collimating lens based on LED light source is designed. The optical design is carried on in two parts separately. One part of the light, whose divergence angle between 0o and 20o, is collimated through a spherical cap contracted the divergence angle and a free-form surface. The other part of light, whose divergence angle between 20o and 80o, is collimated through a compound paraboloid contracted the divergence angle and a free-form surface. The results show that, light angle is less than 4o through this complex collimating lens, and the efficiency of light energy utilization is up to 90%, which could meet requirements for light collimation in current distance..
Laser & Optoelectronics Progress
- Publication Date: Apr. 10, 2014
- Vol. 51, Issue 5, 52204 (2014)
Optical Devices
Influence of Photocuring Time on the Optical Properties of White LED
Sun Haigang, Miao Hongli, and Li Guoqiang
UV-curing method is used to solidify the phosphor in the process of LED packing, the influence of UV curing time on the optical properties of LED is studied. Nine different kinds of curing time is determined in the experiment of LED packing, after packaged, test the physical character of LEDs and then select the fully UV-curing method is used to solidify the phosphor in the process of LED packing, the influence of UV curing time on the optical properties of LED is studied. Nine different kinds of curing time is determined in the experiment of LED packing, after packaged, test the physical character of LEDs and then select the fully cured samples to conduct aging test experiments with constant current and test their photometric &colorimetric parameters regularly. The experimental results show that the adhesive is nearly cured when the curing time is greater than 120 s, the maximum and minimum average wavelength, color temperature and color rendering index of the LEDs for different testing time have a difference of almost 1.2 nm, 200 K, 1.3 respectively for different kinds of curing time, the luminous flux decay rate is higher than others when the curing time is longer than 210 s. So, the suitable curingtime for this kind of UV radiation curing adhesive is 120~180 s under the UV power density of 106.6 mW/cm2. Studying the influence of curing time on properties of LED by optical method is instructive and meaningful to use UV curing coatings in the process of LED packing..
Laser & Optoelectronics Progress
- Publication Date: Apr. 29, 2014
- Vol. 51, Issue 5, 52301 (2014)
Study of Ce:Y3Al5O12 Transparent Ceramics for Application of White Light Emiting Diode
Shi Yun, Wu Lexiang, Hu Chen, Liu Shuping, Li Wei, Kou Huamin, Zeng Yanping, Pan Yubai, Feng Xiqi, and Liu Qian
Ce:Y3Al5O12 transparent ceramics are fabricated by solid state reaction method through vacuum sintering. The in line transmittance in visible light region is higher than 80% . Different doping concentrations (atomic fraction of 0.1%, 0.3%, 0.5%, 1.0%) and thicknesses (0.5, 1.0, 2.0 mm) are investigated by considering tCe:Y3Al5O12 transparent ceramics are fabricated by solid state reaction method through vacuum sintering. The in line transmittance in visible light region is higher than 80% . Different doping concentrations (atomic fraction of 0.1%, 0.3%, 0.5%, 1.0%) and thicknesses (0.5, 1.0, 2.0 mm) are investigated by considering their luninous efficiencies, color rendering index and color temperatures. After being packaged with GaN chip using commercil resin, the prime luninous efficiency reaches to 131.5 lm/W. It is proved that Ce:Y3Al5O12 transparent ceramics will be a promising phosphor prior to powder phophors in white LED devices..
Laser & Optoelectronics Progress
- Publication Date: Apr. 29, 2014
- Vol. 51, Issue 5, 52302 (2014)
Analyse of Night Vision Imaging System Compatibility of LEDs Backlight of LCD
Li Zhengrong, Shen Jian, Pan Libao, Xu Liguo, and Wu Li
The method of evaluating the night vision imaging system (NVIS) compatibility of LCD is analysed in theory, and a method of comparing the contributiveness for NVIS radiance of every monochromatic chip in orange, green and blue (OGB) polychrome LED is pointed out. A LCD with two backlight sources system including white The method of evaluating the night vision imaging system (NVIS) compatibility of LCD is analysed in theory, and a method of comparing the contributiveness for NVIS radiance of every monochromatic chip in orange, green and blue (OGB) polychrome LED is pointed out. A LCD with two backlight sources system including white LEDs and OGB polychrome LEDs is prepared to for experiment. It is proved that, when white LEDs are used as backlight source, the NVIS radiance of LCD is 3.14× 10-8 W/(cm2 ·sr·nm), which is larger than the limit of 2.2× 10-9 W/(cm2 ·sr·nm) in national military standard (GJB), when OGB polychrome LEDs are used as backlight source, the NVIS radiance reduces to 1.958 × 10-9 W/(cm2 · sr · nm), which is accordant with the requirement in GJB. The contribution for NVIS radiance of every monochromatic chip in OGB polychrome LED is compared, the results show that blue chip contributes the most NVIS radiance, red chip less, and green chip the least..
Laser & Optoelectronics Progress
- Publication Date: Apr. 30, 2014
- Vol. 51, Issue 5, 52303 (2014)
Optimizing Design for Sensitivity Improvement of Refractive Index Sensors Based on Photonic Crystal Waveguide
Ke Lintong, Chen Weiye, Zhang Yang, Li Rongsheng, and Shen Yifeng
The transmission spectrum of a two- dimensional photonic crystal waveguide with edge defects of different refractive indexes (RIs) is analyzed, and accordingly a proposal to improve the sensitivity of RI sensor is put forward. The simulations and calculations show that the offset of the upper band edge of the transmissThe transmission spectrum of a two- dimensional photonic crystal waveguide with edge defects of different refractive indexes (RIs) is analyzed, and accordingly a proposal to improve the sensitivity of RI sensor is put forward. The simulations and calculations show that the offset of the upper band edge of the transmission band is related to the RI of the analyte. For the same RI variation, the shift of the upper band edge of the transmission band can be greatly improved by changing the related geometrical parameters of holes at the defect area near both sides of the waveguide. Namely,the sensitivity of the RI sensor is enhanced. In this paper the sensitivity is respectively improved from 55 nm/RIU (RIU means refractive index unit) to 405 nm/RIU and 36 nm/ RIU to 222 nm/RIU corresponding to the range of the variation of RI (Dn) from 0.0 to 1.0 and 1.1 to 2.0 after the optimizing process..
Laser & Optoelectronics Progress
- Publication Date: Apr. 15, 2014
- Vol. 51, Issue 5, 52304 (2014)
Reviews
Research Progress of Micro/nano-Optical Device Based on Chalcogenide Glass
Lü Sheqin, Li Chaoran, Wu Yuehao, Zhang Peiqing, Wang Xunsi, Shen Xiang, Zhang Wei, and Dai Shixun
Micro/nano-optical devices are some optical devices which have micro/nano-scale size，and they have some advantages，such as small volume，high reliability，high coupling efficiency，light weight，flexible design and easy integration. As a novel substrate material of micro/nano-optical device，chalcogenide glass possess some Micro/nano-optical devices are some optical devices which have micro/nano-scale size，and they have some advantages，such as small volume，high reliability，high coupling efficiency，light weight，flexible design and easy integration. As a novel substrate material of micro/nano-optical device，chalcogenide glass possess some unique advantages，such as large infrared transmission window，ultrahigh nonlinear coefficient， smaller two photon absorption coefficient，ultrashort nonlinear response time and tailorable compositions. In recent years，chalcogenide glass micro/nano-optical devices have attracted many attentions. The research progress of chalcogenide glass micro/nano-device is reviewed in terms of chalcogenide glass micro/nano-fiber， microsphere，photonic crystal and microring.Their potential applications and development prospects are also discussed..
Laser & Optoelectronics Progress
- Publication Date: Apr. 01, 2014
- Vol. 51, Issue 5, 50001 (2014)
Research Progress of Laser Propulsion with Liquid Propellants
Sheng Deren, Shi Xiangkun, Chen Jianhong, Yao Hua, and Li Wei
The main research results in recent ten years of laser propulsion with liquid propellants are summarized internally and internationally. The general mechanism of laser propulsion with liquid propellants is analyzed. And the splashing is concluded as the most important constraint of the performance of liquid propellantsThe main research results in recent ten years of laser propulsion with liquid propellants are summarized internally and internationally. The general mechanism of laser propulsion with liquid propellants is analyzed. And the splashing is concluded as the most important constraint of the performance of liquid propellants. Changing the geometries of propellants and increasing the viscosity of liquid are presented as two effective ways to improve propulsive performance. And the performance characteristics of liquid volume, thin film, droplet and highly viscous propellants are commented successively based on the different ways. The hexane film, water droplet and highly viscous solutions are concluded as three kinds of liquid propellants with better integrated propulsive performance. Finally the compound propellant is pointed out to be one of the most important future directions of laser propulsion with liquid propellants..
Laser & Optoelectronics Progress
- Publication Date: Apr. 15, 2014
- Vol. 51, Issue 5, 50002 (2014)
Lunar Laser Communication Demonstration in USA: Terminal Design
Song Tingting, Ma Jing, Tan Liying, Yu Siyuan, and Ran Qiwen
The US National Aeronautics and Space Administration (NASA) has launched the Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft on September 6th, 2013. We review the terminal design of the lunar laser communication demonstration (LLCD) on LADEE, while the experiment design and development of the LLCD wilThe US National Aeronautics and Space Administration (NASA) has launched the Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft on September 6th, 2013. We review the terminal design of the lunar laser communication demonstration (LLCD) on LADEE, while the experiment design and development of the LLCD will be reviewed in another paper. LLCD system mainly includes one space terminal onboard, three earth-based terminals and one earth-based operation center for coordination, where bidirectional laser communications are mainly performed between the space terminal and the multi-aperture telescope array earth-based terminal at downlink data rates up to 622 Mb/s and uplink up to 20 Mb/s. When the weather is considered, two additional earth-based terminals, as back-ups for support, provide geographic diversity..
Laser & Optoelectronics Progress
- Publication Date: Apr. 10, 2014
- Vol. 51, Issue 5, 50003 (2014)
Research Progress in Laser Conditioning of Optical Materials
Shen Chao, Cheng Xiang′ai, Zhu Zhiwu, Jiang Tian, and Dai Yifan
Focusing on the intrinsic mechanism, research progress in laser conditioning of optical materials is reviewed. In terms of material types and laser parameters, theoretical and experimental conditioning results are concluded and analyzed. As a result, the conditioning effects is determined by the evolution rule of defecFocusing on the intrinsic mechanism, research progress in laser conditioning of optical materials is reviewed. In terms of material types and laser parameters, theoretical and experimental conditioning results are concluded and analyzed. As a result, the conditioning effects is determined by the evolution rule of defects under heat. Three quantitative models are discussed in detail. Their merits and demerits are compared, and the modeling tendency of conditioning is pointed out. Finally, the direction of future work is introduced considering problems such as novel research methods, industrial application and improving conditioning gain..
Laser & Optoelectronics Progress
- Publication Date: Mar. 18, 2014
- Vol. 51, Issue 5, 50004 (2014)
Intelligent Pupil Technology Applied on TMA System on Space-Borne Camera
Yan Feng
The off-axis three mirror anastigmatic (TMA) system has been proven a sort of excellent optical system for space-borne camera especially the compact cameras because of its high modulation transfer function (MTF) and large field-of-view (FOV). Several new methods that can be applied on the space-borne TMA system are proThe off-axis three mirror anastigmatic (TMA) system has been proven a sort of excellent optical system for space-borne camera especially the compact cameras because of its high modulation transfer function (MTF) and large field-of-view (FOV). Several new methods that can be applied on the space-borne TMA system are proposed to improve its performance. Because all the improvement is realized by manipulating the pupil function indirectly, these new methods are jointly called intelligent pupil technology..
Laser & Optoelectronics Progress
- Publication Date: Apr. 30, 2014
- Vol. 51, Issue 5, 51101 (2014)
Spectroscopy
Transmission Ratio of Glan-Taylor Prism in Polarization Interference Imaging Spectrometer
Bai Xin, Wu Haiying, Li Yan, and Guo Xiaohong
The transmittance of Glan- Taylor prism (GTP) is a vital index to evaluate the component′s performance. Glan- Taylor prism is the key component of the polarization interference imaging spectrometer (PIIS). We adopt the Raying tracing method to deduce the theoretical transmittance expression of the GTP. By performing thThe transmittance of Glan- Taylor prism (GTP) is a vital index to evaluate the component′s performance. Glan- Taylor prism is the key component of the polarization interference imaging spectrometer (PIIS). We adopt the Raying tracing method to deduce the theoretical transmittance expression of the GTP. By performing the computer simulation, some important relationship curves are obtained with the variations of the transmittance on optical axis and wavelength. The allowed range of the departure angles for the optical axis in the principle section are calculated. The results provide a theoretical guidance for the study and engineering of the polarization interference imaging spectrometer..
Laser & Optoelectronics Progress
- Publication Date: Apr. 30, 2014
- Vol. 51, Issue 5, 53001 (2014)
Nondestructive Identification of Panax Notoginseng and Its Analogues via Laser Raman Spectroscopy
Dong Jingjing, Chen Juan, Ge Yanru, and Qi Xueyong
Panax Notoginseng and its analogues such as Gynura Segetum, Boussingaultia Gracilis and Curcuma Longa are indentified via Raman spectra technique. The characteristic Raman spectra of Panax Notoginseng and its analogues are acquired, then they are indentified by laser Raman spectroscopy and second derivative Raman spectPanax Notoginseng and its analogues such as Gynura Segetum, Boussingaultia Gracilis and Curcuma Longa are indentified via Raman spectra technique. The characteristic Raman spectra of Panax Notoginseng and its analogues are acquired, then they are indentified by laser Raman spectroscopy and second derivative Raman spectroscopy. The structural information indicates that Panax Notoginseng and its analogues contain some carbohydrate substrates, due to some characteristic vibration peaks of carbohydrate moiety, because 1330, 1040, 943 and 310 cm-1 characteristic absorption peaks can be observed．The characteristic vibration peaks at 1080 cm-1 and 1120 cm-1 indicate the existence of saponin compounds. Chrysanthemum Notoginseng shows characteristic vibration peaks at 820, 899, 1144 and 2935 cm-1 because of the presence of b-sitosteroland, pyrrolizidine alkaloids compounds and long chain aliphatic compounds. The characteristic vibration peaks at 1462 cm-1 and 1695 cm-1 appear in Rattan Notoginseng spectroscopy, because of the existenence of adenosine compounds and uracil compounds． The characteristics vibration peaks of Rhizoma Curcumae Longae, such as 962, 1187, 1433, 1596 and 1630cm-1can also be observed due to some curcumin compounds. The difference of absorption peaks between Panax Notoginseng and its analogues can be used to distinguish them. Finger spectroscopy of Panax Notoginseng and its analogues can be further established, the identification results can be further verified via second derivative Raman spectroscopy. The above method can be easily used to provide a more accurate, direct and fast identification of Panax Notoginseng and its analogues..
Laser & Optoelectronics Progress
- Publication Date: Mar. 21, 2014
- Vol. 51, Issue 5, 53002 (2014)
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