Journals >Laser & Optoelectronics Progress
Contents
2012
Volume: 49 Issue 3
27 Article(s)
Export citation format
Atmospheric Optics and Oceanic Optics
Centroid Detection Error Analysis of a Point Source with a Single Blind Pixel in Spot Area
Wang Shaobai, Wang Chunhong, and Rao Changhui
In the detection of a point source with Hartmann wavefront sensor, besides the normal noise sources such as signal photon noise, readout noise and background noise, the blind pixels existing on the image sensor may also introduce centroid detection error. The integral formula of centroid detection error in the presenceIn the detection of a point source with Hartmann wavefront sensor, besides the normal noise sources such as signal photon noise, readout noise and background noise, the blind pixels existing on the image sensor may also introduce centroid detection error. The integral formula of centroid detection error in the presence of a single blind pixel in the spot area is put forward. Furthermore, analysis about the two influence factors of centroid displacement error induced by single blind pixel, i.e., the distance between single blind pixel and spot center and the Gaussian width of the spot is presented. The simulation and experimental results are in accordance with the theoretical analysis..
Laser & Optoelectronics Progress
- Publication Date: Jan. 12, 2012
- Vol. 49, Issue 3, 30101 (2012)
Automatic Inversion Algorithm of Cloud Cover of Laser Ceilometer
Yang Chengwu, Liu Wenqing, and Zhang Yujun
Cloud is one of the important factors in the field of meteorology forecasting and navigation and so on. Therefore, it is important to measure cloud. As one of the important meteorological parameters, the cloud cover has become an important part of meteorological observations. So far, the measurement of cloud cover mainCloud is one of the important factors in the field of meteorology forecasting and navigation and so on. Therefore, it is important to measure cloud. As one of the important meteorological parameters, the cloud cover has become an important part of meteorological observations. So far, the measurement of cloud cover mainly relies on visual observation, which leads to large deviations because of various factors. Measuring the cloud cover is an important application of laser ceilometer. An automatic inversion algorithm of cloud cover of laser ceilometer is proposed in this paper. The purpose of the algorithm is to construct a two-dimensional image of time and cloud height based on the ceilometer measurements only from a single point. The cloud cover is calculated according to the ratio of time occupied by clouds. The comparative experiments show that the algorithm can more accurately calculate the cloud cover information, and it is of great practical value for laser ceilometer..
Laser & Optoelectronics Progress
- Publication Date: Dec. 23, 2011
- Vol. 49, Issue 3, 30102 (2012)
DIMM System for Tracking Motion Target and Calculating the Atmospheric Coherence Length along Slant Propagation Path
Xu Peng, Wang Jianye, Shao Hui, Wu Yi, and Li Guang
A new differential image motion monitor (DIMM) system for measuring atmospheric coherence length which can track motion target is developed. The system uses a new algorithm which is composed of genetic algorithm and iterative centroid algorithm to process differential image and calculate the offset of the target and thA new differential image motion monitor (DIMM) system for measuring atmospheric coherence length which can track motion target is developed. The system uses a new algorithm which is composed of genetic algorithm and iterative centroid algorithm to process differential image and calculate the offset of the target and the covariance of the angle-of-arrival fluctuation in realtime. So, it can track motion targets and measure the atmospheric coherence length. In experiment, we use a halogen lamp tied in a stratosphere balloon at the altitude of 35 km as the lamp-house to measure the atmospheric coherence length along slant propagation path. Simultaneously, we put another instrument 5 m away from the new system which selects the solar limb as the lamp-house to measure the total layer atmospheric coherence length. The result indicates a linear correlation between the two groups of data. At last, we analyze and discuss the feasibility of a method which can use laser guide star to measure the total layer atmospheric coherence length..
Laser & Optoelectronics Progress
- Publication Date: Dec. 23, 2011
- Vol. 49, Issue 3, 30103 (2012)
Fiber Optics and Optical Communications
Study on the Dual-Parameter Sensing Technology of Brillouin Optical Time Domain Analyzer Based on Dual-Optical-Fiber
Xie Hang, Song Muping, and Ye Xianfeng
For the Brillouin-based distributed optical fiber sensor (DOFS), the change of temperature or strain can cause the alteration of Brillouin frequency shift, so there exists the cross sensitivity problem. In the previous research of dual-parameter sensing of Brillouin optical time domain refrectometer (BOTDR), the frequeFor the Brillouin-based distributed optical fiber sensor (DOFS), the change of temperature or strain can cause the alteration of Brillouin frequency shift, so there exists the cross sensitivity problem. In the previous research of dual-parameter sensing of Brillouin optical time domain refrectometer (BOTDR), the frequency shift and optical power of the single fiber are detected simultaneously for dual-parameter sensing. However, for Brillouin optical time domain analyzer (BOTDA), because of the polarization-related stimulated Brillouin scattering, the power of the scattering light cannot be accurately detected and it is difficult to achieve dual-parameter sensing with a single fiber. Here two fibers with different temperature and strain coefficients are used for dual-parameter sensing. The temperature and strain coefficients of different optical fibers are obtained experimentally, based on which G652 fiber and G652 cable fiber are selected; their temperature and strain coefficients are used to construct the coefficient matrix. By simultaneously detecting these two optical fibers′ Brillouin frequency shift, temperature and strain are successfully sensed. The temperature resolution is about 25 ℃, and the strain resolution is about 200 με..
Laser & Optoelectronics Progress
- Publication Date: Dec. 23, 2011
- Vol. 49, Issue 3, 30601 (2012)
The Design on Gain Flatness of Distributed Broadband Fiber Raman Amplifie
Zhou Weijun, Xu Ming, and Wang Rongbo
Introducing power coupling equation of Raman dispersion on distributed broadband fiber Raman amplifier, establishing mathematics model of pumps and signals. At the base of this, the on-off gain of the C+L waveband was calculated, analyzing main factors which affected gain flatness. By adjusting pump powers reasonably, Introducing power coupling equation of Raman dispersion on distributed broadband fiber Raman amplifier, establishing mathematics model of pumps and signals. At the base of this, the on-off gain of the C+L waveband was calculated, analyzing main factors which affected gain flatness. By adjusting pump powers reasonably, making gain flatness be improved commendably..
Laser & Optoelectronics Progress
- Publication Date: Nov. 28, 2011
- Vol. 49, Issue 3, 30602 (2012)
Analysis and Methodology Study of Bit Error Performance of FSO System
Jia Kejun, Zhao Yangang, Chen Hui, Xue Jianbin, and Wang Huiqin
Bit error rate (BER) is an important evaluation index of free space optical communication (FSO), and how to exactly get the BER statistics is rather important. We study the technique of analyzing the BER of FSO based on Monte Carlo simulation using Matlab software. The FSO system and the principle of Monte Carlo simulaBit error rate (BER) is an important evaluation index of free space optical communication (FSO), and how to exactly get the BER statistics is rather important. We study the technique of analyzing the BER of FSO based on Monte Carlo simulation using Matlab software. The FSO system and the principle of Monte Carlo simulation are introduced. The method of getting the BER statistics is researched, and the method of generating information source, the channel model, and the calculation of signal-to-noise ratio (SNR) parameter for simulation are given detailedly. Moreover, part of the core Matlab program is presented. The modeling and simulation based on the low-density parity check (LDPC) code and pulse position modulation (PPM) are implementted. The analysis results under different conditions of weather and signal-to-noise ratio indicate the this method is accurate and pratical..
Laser & Optoelectronics Progress
- Publication Date: Jan. 12, 2012
- Vol. 49, Issue 3, 30603 (2012)
Holography
The Influence of Shearing Quantity Selection in Shearing Interferometry Noise Reduction
Lin Chao, Qian Xiaofan, Rao Fan, Li Bin, and Li Xinghua
As there exists speckle noise in the phase of optical field obtained from holographic interferometry, it is necessary to reduce noise so that phase unwrapping can be successfully completed. Separating noise from the optical field through shearing is an effective method, but the study on influence of shearing quantity sAs there exists speckle noise in the phase of optical field obtained from holographic interferometry, it is necessary to reduce noise so that phase unwrapping can be successfully completed. Separating noise from the optical field through shearing is an effective method, but the study on influence of shearing quantity selection is still needed. Through theoretical analysis, simulation computation and experimental validation, it is proved that shearing quantity has influence on the linear correlation between the phase of ideal shearing optical field and the phase of shearing optical field containing noise, and the difficulty of noise reduction is changed. The phase linear correlation coefficient reaches a maximum through selecting appropriate shearing quantity, thus the best noise reduction result can be achieved..
Laser & Optoelectronics Progress
- Publication Date: Dec. 23, 2011
- Vol. 49, Issue 3, 30901 (2012)
Measuring Small Displacement of Objects by Using Double-Exposure Hologram Interference Field
Hu Jie, Qin Yanli, and Li Ting
Double-exposure method is a technique in which a standard object is exposed twice and the wavefronts reflected from the object before and after the change are recorded on the same hologram at different time. As a result， two first-order interference fields are produced without the introduction of a reference plane. A sDouble-exposure method is a technique in which a standard object is exposed twice and the wavefronts reflected from the object before and after the change are recorded on the same hologram at different time. As a result， two first-order interference fields are produced without the introduction of a reference plane. A second-order interference field is created by the two wavefronts during reconstruction process. The relationship among the second-order interference field， small displacement， light phase change and rotation angle is invesgated by using experiments combined with computer simulation. The small displacements of rigid diffuse objects are measured using double-exposure hologram. Experimental results show that the stripes of the objects appear in the vicinity of the localized space curves， and their sharpness depends on the aperture of the observing system..
Laser & Optoelectronics Progress
- Publication Date: Jan. 12, 2012
- Vol. 49, Issue 3, 30902 (2012)
Measurement of Temperature Field Based on Digital Holography Technology
Jia Jinchao, Mo Weidong, Li Zhaoxiang, Xu Ruiyang, Zhu Haoran, Jia Jun, and Lian Chen
The tiny change of temperature changes the refractive index of air, and then leads to the phase change of light propogating through the area where the refractive index has changed. We measure the change of temperature field by using Michelson interferometer and digital holography method. Our technique combined with digThe tiny change of temperature changes the refractive index of air, and then leads to the phase change of light propogating through the area where the refractive index has changed. We measure the change of temperature field by using Michelson interferometer and digital holography method. Our technique combined with digital photography can be used to measure hydrofield distribution and changing process, for instance, the density distribution and changing process in airflow and water stream..
Laser & Optoelectronics Progress
- Publication Date: Jan. 12, 2012
- Vol. 49, Issue 3, 30903 (2012)
Lasers and Laser Optics
Design and Thermal Effect Analysis of a Double-Semi-Cylinder Laser
Wu Zhaohui, Guo Qiang, Zhou Jian, Wang Shouzhang, and Huang Li
We design a double-semi-cylinder laser in order to solve the problem that the beams of slab laser, disk laser and tube laser are difficult to focus because they are not round and the problem of rod laser with a poor thermal effect. The beam of double-semi-cylinder laser can be round and its thermal effect is much betteWe design a double-semi-cylinder laser in order to solve the problem that the beams of slab laser, disk laser and tube laser are difficult to focus because they are not round and the problem of rod laser with a poor thermal effect. The beam of double-semi-cylinder laser can be round and its thermal effect is much better than rod laser. Results of numerical analysis with ANSYS software show that the highest temperature of double-semi-cylinder laser is about 25 ℃ lower than that of rod laser; its largest temperature difference is about 11 ℃ lower, and its largest thermal strain is less than 60% of that of rod laser..
Laser & Optoelectronics Progress
- Publication Date: Dec. 23, 2011
- Vol. 49, Issue 3, 31401 (2012)
Study of F-P Etalon Using in Lasers
Xue Junwen, Pei Xuedan, Su Binghua, Sun Lu, and Zhao Huiyuan
The general transmission formula of F-P etalon including different reflectivity and absorption is derived. When the reflectivities of the two surfaces are the same and the absorption is ignored, the general formula will become the common formula in the documents or books. When the reflectivities are different and the aThe general transmission formula of F-P etalon including different reflectivity and absorption is derived. When the reflectivities of the two surfaces are the same and the absorption is ignored, the general formula will become the common formula in the documents or books. When the reflectivities are different and the absorption is ignored, the maximum transmission is not 100%, but there is a certain reflectivity. Moreover if the difference between the reflectivities of the two surfaces is bigger, the effect becomes more obvious..
Laser & Optoelectronics Progress
- Publication Date: Jan. 05, 2012
- Vol. 49, Issue 3, 31402 (2012)
Application of Laser Processing Technologies on Turbine Blades
Yao Jianhua, Ye Zhong, and Shen Hongwei
With different laser processing technologies such as laser alloying, laser repairing and laser solid solution strengthening, two kinds of steam turbine blades with 2Cr13 and 17-4PH are hardened and repaired. Before and after hardening or remanufacturing, the microstructures, microhardness, residual stress, wear resistaWith different laser processing technologies such as laser alloying, laser repairing and laser solid solution strengthening, two kinds of steam turbine blades with 2Cr13 and 17-4PH are hardened and repaired. Before and after hardening or remanufacturing, the microstructures, microhardness, residual stress, wear resistance, anti-corrosion and anti-cavitations properties are measured. The results confirm that laser processing technologies could be applied to strengthen and repair turbine blades..
Laser & Optoelectronics Progress
- Publication Date: Feb. 07, 2012
- Vol. 49, Issue 3, 31403 (2012)
Materials
Study of Synthesis and Luminescent Characterization of the Coordinated Nano Terbium Oxide Colloids
Chen Qianhuo, Li Qing, Wang Wenjing, and Sheng Yu
Colloids of the coordinated terbium oxide are prepared by colloids precipitation method with ligands of acetylacetone (acac) and 2,2-bipyridine and pH regulating agent of NaOH solution. The fluorescent properties and structure of nanoparticles of the coordinated terbium oxide are characterized by fluorescence spectra, Colloids of the coordinated terbium oxide are prepared by colloids precipitation method with ligands of acetylacetone (acac) and 2,2-bipyridine and pH regulating agent of NaOH solution. The fluorescent properties and structure of nanoparticles of the coordinated terbium oxide are characterized by fluorescence spectra, ultraviolet-visible spectra and high-resolution transmission electron microscopy (HRTEM). The results show that the nano terbium oxide particles coordinated by acac and 2,2′-bipy can radiate intense green light under ultraviolet irradiation, and their fluorescence spectrum presents typical characteristic emission peaks of Tb3+ ions. The HRTEM and selected area electron diffraction (SED) results show that the nanoparticles are terbium oxide with the size of 6 nm..
Laser & Optoelectronics Progress
- Publication Date: Jan. 12, 2012
- Vol. 49, Issue 3, 31601 (2012)
Luminescence Properties of Tungstate Phosphors Doped with Rare-Earth Ion
Fan Gongqi, Lin Haifeng, Shi Fenghua, Xu Wenfei, and Wang Haibo
The preparation of red phosphor in the phosphor-converted white LED is indispensable, and plays a very important role in improving the color rendering index. As a newly developed kind of red phosphor, LiEuW2O8 shows great potential. The luminescence properties of LiEuW2O8 phosphor doped with rare-earth ions are studiedThe preparation of red phosphor in the phosphor-converted white LED is indispensable, and plays a very important role in improving the color rendering index. As a newly developed kind of red phosphor, LiEuW2O8 shows great potential. The luminescence properties of LiEuW2O8 phosphor doped with rare-earth ions are studied. LiEu1-xRExW2O8 (RE=La and Sm) series red phosphors are produced by the high-temperature solid-phase synthesis method. When La3+ and Sm3+ replace Eu3+ in LiEuW2O8, both of them transfer energy to Eu3+ through reabsorption and thus realizing sensibilization of Eu3+. After being doped with La3+ and Sm3+, the excitation and emission peaks of LiEuW2O8 and the crystal structure do not change; however, the luminescence intensity is improved. With the addition of La3+ and Sm3+ of 3% and 4% (molar fraction), respectively, the luminescence intensity reaches the maximum..
Laser & Optoelectronics Progress
- Publication Date: Jan. 19, 2012
- Vol. 49, Issue 3, 31602 (2012)
Medical Optics and Biotechnology
Approximate Entropy Evaluation of EEG θ Rhythm Based on Low-Frequency Photon Stimuli
Ding Shangwen, Qian Zhiyu, Li Weitao, Tao Ling, Hu Guangxia, and Zheng Yang
Utilizing the approximate entropy algorithm, the changes of approximate entropy of electroencephalogram (EEG) θ rhythm (Apen θ) about 19 healthy volunteers before and after 5 Hz frequency photon stimulation (light repeatedly inducing 5 times per second) are analyzed. The results of T-test(P<0.05) show that the 5 Hz Utilizing the approximate entropy algorithm, the changes of approximate entropy of electroencephalogram (EEG) θ rhythm (Apen θ) about 19 healthy volunteers before and after 5 Hz frequency photon stimulation (light repeatedly inducing 5 times per second) are analyzed. The results of T-test(P<0.05) show that the 5 Hz photon stimulation can significantly reduce the Apen θ of EEG θ rhythm. These changes can be obviously observed at the forehead, parietal, temporal and occipital region, and the most significant changes happen at temporal region and occipital region. The average Apen θ values about left and right brain EEG are both reduced after photon stimulation, and the Apen θ about right brain EEG is reduced more obviously. It can be concluded that Apen θ induced by external optical stimuli can describe different EEG rhythm characteristics and quantitatively show the extent of photon stimulation..
Laser & Optoelectronics Progress
- Publication Date: Jan. 05, 2012
- Vol. 49, Issue 3, 31701 (2012)
Research on Influencing Factors of Milk Aqueous Solution Fluorescence Spectrum
Gu Chunfeng, Lan Xiufeng, Yu Yinshan, and Lu Liping
Three-dimensional fluorescence spectra of pure milk, milk with high calcium, milk with high calcium and low fat, and pure milk expiring by about 10 days are researched. The experiment indicates that the fluorescence peak of milk aqueous solution shows red shift with the increase of stimulation wavelength. When the stimThree-dimensional fluorescence spectra of pure milk, milk with high calcium, milk with high calcium and low fat, and pure milk expiring by about 10 days are researched. The experiment indicates that the fluorescence peak of milk aqueous solution shows red shift with the increase of stimulation wavelength. When the stimulation wavelength is longer than 340 nm, a secondary fluorescence peak appears in the fluorescence spectrum, and it also shows red shift with the increase of stimulation wavelength. By comparison it is found that the concentration has little effect on fluorescence spectrum of milk aqueous solution, while the species of milk has greater impact, especially the milk with high calcium and low fat. The reason why the fluorescence intensities of the milk with high calcium and low fat and the expired milk are stronger under certain stimulation wavelength is analyzed preliminary. The findings may provide reference when using the fluorescence spectrum to identify milk quality..
Laser & Optoelectronics Progress
- Publication Date: Jan. 05, 2012
- Vol. 49, Issue 3, 31702 (2012)
Optical Design and Fabrication
Influence of Diversification of Elevation to the Opto-Mechanical System of 1.23 m Telescope
Yang Fei, Ming Ming, Chen Baogang, Wang Fuguo, and Wei Peifeng
Considering both the opto-mechanical design and the image quality analysis of the 1.23 m aperture telescope, we build the opto-mechanical system which can fit the diversification of elevation from 0°~90°. The opto-mechanical system can meet the requirements of imaging of the telescope. However, there are someConsidering both the opto-mechanical design and the image quality analysis of the 1.23 m aperture telescope, we build the opto-mechanical system which can fit the diversification of elevation from 0°~90°. The opto-mechanical system can meet the requirements of imaging of the telescope. However, there are some deformations in the tube of telescope with the diversification of elevation due to the gravity, and they result in distortion of the image. The main influencing factor of the diversification of elevation to the telescope is defocusing, and some material compensation methods are proposed to satisfy the requirements of observation. Meanwhile, some feasible opinions for the observational experiments and upgrading of telescopes with 1.23 m or more larger aperture are given..
Laser & Optoelectronics Progress
- Publication Date: Dec. 28, 2011
- Vol. 49, Issue 3, 32201 (2012)
Study on Characteristics of Silicon Modification Layer on Silicon Carbide Surface
Zhang Feng, Fan Di, and Gao Jinsong
In order to achieve high quality optical aspheric silicon carbide (SiC) mirror, the SiC surface must be modified primarily. Firstly, the modification technology of ion beam assisted deposition (IBAD) for depositing silicon (Si) on SiC mirror surface is introduced. Then, some characteristics, such as mechanical performaIn order to achieve high quality optical aspheric silicon carbide (SiC) mirror, the SiC surface must be modified primarily. Firstly, the modification technology of ion beam assisted deposition (IBAD) for depositing silicon (Si) on SiC mirror surface is introduced. Then, some characteristics, such as mechanical performance, optical fabrication capability, surface roughness and reflectivity, of Si modification layer on SiC surface are studied. The results of experiments show that the mechanical performance and the optical fabrication capability of Si modification layer on SiC surface are excellent. After polishing, the surface roughness and reflectivity of the Si modification layer on SiC are 0.85 nm \[root mean square (RMS)\] and 98.5%, respectively. Finally, an example of Si-modified SiC off-axis aspheric mirror (Ф600 mm) is polished by computer-controlled optical surfacing technology. The testing result indicates that the surface accuracy of the mirror is 0.018λ （λ=0.6328 μm） RMS. It can meet the technical requirements of high quality space optical aspheric mirror..
Laser & Optoelectronics Progress
- Publication Date: Jan. 05, 2012
- Vol. 49, Issue 3, 32202 (2012)
Design of CCD Camera Based on Gigabit Ethernet
Men Jinrui, Yao Dazhi, and Wei Wei
Domestic science-grade CCD camera generally uses USB 2.0 and its transmission speed is low. Thus, transmission distance is relatively short. In this paper, a CCD camera based on gigabit ethernet interface is designed. A NIOS II soft core system is established by using Altera Company′s FPGA (Cyclone II series) as the coDomestic science-grade CCD camera generally uses USB 2.0 and its transmission speed is low. Thus, transmission distance is relatively short. In this paper, a CCD camera based on gigabit ethernet interface is designed. A NIOS II soft core system is established by using Altera Company′s FPGA (Cyclone II series) as the control system, and a gigabit ethernet transmission system by using the physical layer chip and data link layer chip structure. The transmission speed of the system is up to 700 Mbit/s, and the transmission distance is up to 50 m, so the existing two problems of CCD camera can be overcome..
Laser & Optoelectronics Progress
- Publication Date: Jan. 05, 2012
- Vol. 49, Issue 3, 32203 (2012)
Optical System of the Probe for a Micro-Raman Spectrometer
An Yan, Sun Qiang, Piao Renguan, Liu Ying, and Li Chun
In order to meet the requirements of a designed and manufactured micro-Raman spectrometer with numerical aperture of 0.04 and operation wavelength from 781 nm to 1014 nm, two types of the optical systems of the Raman probe are designed. One is the traditional spherical system, and the other, the aspheric system. The scIn order to meet the requirements of a designed and manufactured micro-Raman spectrometer with numerical aperture of 0.04 and operation wavelength from 781 nm to 1014 nm, two types of the optical systems of the Raman probe are designed. One is the traditional spherical system, and the other, the aspheric system. The scatter light collection system is a single lens with large numerical aperture, and the light converge system is a kind of telephoto lens formed by a “thick double-cemented lens”. An excellent telephoto ratio of 0.59 of the system is achieved, which reduces the optical system of the probe greatly. It is shown that the traditional spherical system has a numerical aperture of 0.33 at the object space, with the spot diagram radius less than 30 μm and the relative illumination at the image plane higher than 80%. The aspheric system has a numerical aperture of 0.4 at the object space, with the spot diagram radius less than 20 μm and the relative illumination at the image plane higher than 80%. The overall length of the optical system is 150 mm, which meets the requirements of the compact and portable micro-Raman spectrometer..
Laser & Optoelectronics Progress
- Publication Date: Jan. 05, 2012
- Vol. 49, Issue 3, 32204 (2012)
Optical Devices
Influence of Phosphor Concentration and Current Intensity on Phosphor-Based White LED Characteristics
Li Liang, Jin Shangzhong, Cen Songyuan, Liang Pei, Wang Le, and Cao Yujie
LED packaging is crucial for the development of solid-state lighting. The common method of making WLED is to mix the blue light from the LED die and the wavelength converted yellow light from the phosphor layer. We discuss the influence of phosphor concentration and drive current intensity on white LED characteristics.LED packaging is crucial for the development of solid-state lighting. The common method of making WLED is to mix the blue light from the LED die and the wavelength converted yellow light from the phosphor layer. We discuss the influence of phosphor concentration and drive current intensity on white LED characteristics. Software simulations and real packagings are adopted for the study. Influences of phosphor concentration on luminous flux and correlated color temperature (CCT) for white LED are investigated with three-dimensional ray tracing simulations and the results are verified by real packaging. In addition, junction temperature and color rendering of white LED are also investigated. The results show that CCT decreases with the increase of phosphor concentration, however, luminous flux achieves an optimal value and then decreases. The increased junction temperature caused by phosphor concentration and drive current intensity change degrades the phosphor conversion efficiency. For the color rendering of white LED, a higher phosphor concentration leads to a lower color rendering index, and the color rendering index increases with the increase of drive current intensity till it achieves stabilization..
Laser & Optoelectronics Progress
- Publication Date: Jan. 12, 2012
- Vol. 49, Issue 3, 32301 (2012)
Secondary Optical Simulation of LED Based on Goniophotometer Experiment
Hai Yang, Yang Daoguo, and Hou Fengze
TracePro software and goniophotometers are used to carry out the optical simulation and experimental researches on LED, respectively. Comparing the test results with the simulation results, the accuracy and feasibility of the simulation method are verified. TracePro is used to carry out the optimization of secondary opTracePro software and goniophotometers are used to carry out the optical simulation and experimental researches on LED, respectively. Comparing the test results with the simulation results, the accuracy and feasibility of the simulation method are verified. TracePro is used to carry out the optimization of secondary optical simulation for high power LED. Results that show the optical performance of high power LED has been greatly improved by the optimization optical design. The lighting effect is more ideal, and the light uniformity is much better..
Laser & Optoelectronics Progress
- Publication Date: Jan. 12, 2012
- Vol. 49, Issue 3, 32302 (2012)
Reviews
Femtosecond Optical Frequency Combs for Precision Measurement Applications
Wu Xuejian, Li Yan, Wei Haoyun, and Zhang Jitao
The femtosecond optical frequency comb based on mode-locked laser is a laser source which can emit trains of pulses with stable repetition rate, and the spectrum of the pulses consists of a comb of optical frequencies with equal spacing. Femtosecond optical frequency combs can link the microwave frequency to the opticaThe femtosecond optical frequency comb based on mode-locked laser is a laser source which can emit trains of pulses with stable repetition rate, and the spectrum of the pulses consists of a comb of optical frequencies with equal spacing. Femtosecond optical frequency combs can link the microwave frequency to the optical frequency, achieving the direct measurement of absolute optical frequency. Besides, as special lasers different from traditional stabilized continuous wave lasers, femtosecond optical frequency combs present superiorities in the optical precision measurement areas such as laser frequency rulers, absolute distance measurements and precision spectroscopy measurements. The recent progress, key techniques and potential directions of femtosecond optical frequency combs for precision measurement applications are reviewed. Femtosecond optical frequency combs will play an important role in the field of optical precision measurements in future..
Laser & Optoelectronics Progress
- Publication Date: Jan. 12, 2012
- Vol. 49, Issue 3, 30001 (2012)
Research of the Compressive Imaging Technology
Chen Jing, and Wang Yongtian
The conventional optical imaging system is based on Nyquist sampling theorem, which seriously wastes valuable sensing resources and increases overall system cost. Applying compressive sensing theory to practical imaging systems can overcome the conventional imager′s design idea. Hardware is used to implement the non-adThe conventional optical imaging system is based on Nyquist sampling theorem, which seriously wastes valuable sensing resources and increases overall system cost. Applying compressive sensing theory to practical imaging systems can overcome the conventional imager′s design idea. Hardware is used to implement the non-adaptive linear projection of target objects and compressive imaging by using a smaller number of photonic detectors is realized. This paper reviews several key problems in compressive sensing theory and discusses the existing difficult problems. The principle and difficulties of the compressive imaging systems are also discussed in detail..
Laser & Optoelectronics Progress
- Publication Date: Dec. 07, 2011
- Vol. 49, Issue 3, 30002 (2012)
The Research and Application of Ultrafastlaser Microstructured Silicon
Chen Changshui, He Huili, Li Jianghua, and Liu Songhao
Black silicon with quasi-regular arrays of micrometer-sized spikes, which is obtained by irradiating the surface of a Si wafer with ultrafast laser pulses in the presence of a chalcogen-bearing gas, or prepared by ion implantation and pulsed-laser-melting-induced rapid solidification, holds great promise in the preparaBlack silicon with quasi-regular arrays of micrometer-sized spikes, which is obtained by irradiating the surface of a Si wafer with ultrafast laser pulses in the presence of a chalcogen-bearing gas, or prepared by ion implantation and pulsed-laser-melting-induced rapid solidification, holds great promise in the preparation of high performance intermediate band solar cells. This new material has unusual optical and electrical properties, such as strong absorption of light with wavelength between 0.25 μm and 17 μm, nice field emission characteristics and so on, offers silicon many new features. Professor Mazur predicted that black silicon would have incomparable superiority to other materials in solar cell field. Besides, black silicon has important potential applications in the fields of detector, sensor, display technology, microelectronics and so on. The forming mechanism, recent development, photoelectric characteristics and application prospect of black silicon are introduced in this paper..
Laser & Optoelectronics Progress
- Publication Date: Jan. 12, 2012
- Vol. 49, Issue 3, 30003 (2012)
Development of All-Solid-State Medical Laser for Skin Vascular Dermatosis
Tian Yubing, Tan Huiming, Cui Jinjiang, Wang Fan, Shi Yanbo, and Dong Ningning
The treatment of skin vascular disease with all-solid-state laser is a safe, effective and successful option. We review literatures on the laser technique for treatment of skin vascular disease. The absorption peak of oxyhemoglobin and the selective absorption principle of tissue are introduced. The main techniques forThe treatment of skin vascular disease with all-solid-state laser is a safe, effective and successful option. We review literatures on the laser technique for treatment of skin vascular disease. The absorption peak of oxyhemoglobin and the selective absorption principle of tissue are introduced. The main techniques for generating 418, 542 and 577 nm laser are discussed. The yellow 577 nm medical laser techniques including frequency doubling, sum frequency mixing, stimulated Raman scattering (SRS), optical parametric oscillator (OPO)and optically pumped semiconductor (OPS) are emphasized. The advantages and the development trend of different ways are pointed out. In the discussion of sum frequency mixing, the new scheme to produce 578 nm laser by employing thin disc and end-pumping configuration is demonstrated..
Laser & Optoelectronics Progress
- Publication Date: Jan. 05, 2012
- Vol. 49, Issue 3, 30004 (2012)
Reversible Saturable Optical Transitions Based Fluorescence Nanoscopy
Hao Xiang, Kuang Cuifang, Li Yanghui, and Liu Xu
The reversible saturable optical transitions (RESOLFT) based fluorescence nanoscopy, which fundamentally breaks the barrier of the diffraction limit in the far field, is expected to be widely used in biology, chemistry and medicine domain. This paper reviews the history of fluorescence nanoscopy technology, summarizes The reversible saturable optical transitions (RESOLFT) based fluorescence nanoscopy, which fundamentally breaks the barrier of the diffraction limit in the far field, is expected to be widely used in biology, chemistry and medicine domain. This paper reviews the history of fluorescence nanoscopy technology, summarizes some general RESOLFT approaches, and explicitly describes their corresponding characters, especially the advantages and drawbacks. The new improvement in related domains are also shown..
Laser & Optoelectronics Progress
- Publication Date: Jan. 07, 2012
- Vol. 49, Issue 3, 30005 (2012)
© Copyright 2018-2021 | Chinese Laser Press. All Rights Reserved 沪ICP备15018463号-20