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ISSN1001-3806 CN51-1125/TN Map

2011 Vol. 35, No. 5

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Research of partial penetrated laser overlap-welding of thin steel sheet
CHEN Gen-yu, CHEN Ming, LI Shi-chun, TAN Li-peng
2011, 35(5): 577-581. doi: 10.3969/j.issn.1001-3806.2011.05.001
Abstract:
In order to study the welding quality of partial penetrated laser overlap-welding of thin steel sheet, SUS304 austenitic stainless steel and SPCC cold-rolled steel sheet were welded with fiber laser and CO2 laser. And the main factors affecting the partial penetrated laser welding were analyzed. The micro-structure and the mechanical properties of the weld were measured, finally, the effects of main welding parameters, including laser power, welding speed, defocus distance, pulse frequency and duty ratio, on weld surface quality and performance were obtained. The results show that under the proper welding condition, the weld topography is uniform and continuous, the strength of weld is 50% higher than that of base metal, and its micro-hardness of fusion zone is higher than that of base metal.
Influence of laser shock processing on friction and wear properties of magnesium alloy
CHEN Ju-fang, YE Xia, SHEN Lai-di, LI Xing-cheng
2011, 35(5): 582-585,647. doi: 10.3969/j.issn.1001-3806.2011.05.002
Abstract:
In order to study the influence of laser shock processing on the friction and wear properties of magnesium alloy, some AM50 specimens were processed with Nd:glass pulse laser, and the surface morphology, roughness, microstructure, micro-hardness and frictional characterization were examined and analyzed. The experimental results showed that, after laser shock processing, the surface roughness was increased slightly, a lot of dislocations and twins were found in the strengthening layer, hardness was improved significantly, surface micro-hardness was improved to about 67HV as compared with about 40HV of the substrate, and the depth of strengthening layer was about 0.8mm. The friction and wear behaviors were investigated using a ball-on-flat apparatus under dry sliding condition. It was found that the main wear mechanism was abrasive wear, the friction coefficient curve of the LSP specimen was similar to that of the untreated specimen, and the wear volume of the LSP specimen was slightly bigger than that of the untreated specimen. Although the effect of laser shock strengthening magnesium alloy is evident, the influence of laser shock processing on the friction and wear properties of magnesium alloy is slight.
Application of COM component in digital holography
HU Zhen-hua, FU Yun-chang, ZHANG Yong-an, DU Yuan
2011, 35(5): 586-588. doi: 10.3969/j.issn.1001-3806.2011.05.003
Abstract:
MATLAB with powerful ability of the data and image processing and software Visual Basic(VB) with simple programming and visualization were combined and dynamic link library(DLL) technology which formed using the component object model(COM) component of MATLAB in VB software interface was used in digital holographic processing. It is shown that this can reduce the programming time, and it is convenient and easy to modify parameters. Furthermore the efficiency of the holographic image post-processing is improved so that the results, such as velocity and position of moving particles in reconstruction image can be obtained rapidly, and the developed method is of practical significance.
Research of reconstruction of temperature field by means of digital holography and Radon transform
WANG Zhan-liang, ZHANG Yong-an, QIAN Xiao-fan
2011, 35(5): 589-592. doi: 10.3969/j.issn.1001-3806.2011.05.004
Abstract:
In order to obtain the temperature distribution of temperature field, using of the digital holography, adopting the reconstruction theory of drawing layer based on Randon transform into the final image processing in digital holography, after theoretical analysis and experimental validation, 3-D phase and temperature data of the temperature field were obtained. The 3-D temperature reconstructed with this method is conformal with that reconstucted with Abel method so that it is feasible.
Study about distortion measurement of NFOV lens based on star point method
XV Wei-xing, QIAO Wei-dong, YANG Jian-feng, GE Wei, XUE Bin, MA Li-hua
2011, 35(5): 593-595,643. doi: 10.3969/j.issn.1001-3806.2011.05.005
Abstract:
In order to measure the distortion of the narrow field of view (NFOV) lens by means of star point method, both star point center orientation and star size, affecting the accuracy of the distortion measurement, were studied. First of all, in order to improve the star positioning accuracy, Otsu algorithm and the barycenter calculation were combined to calculate the location of star point. At the same time, the calculated results were compared with the traditional centroid algorithm. Then, the effect of the star size on the stability of the star point positioning was analyzed in the experiments. Finally, the absolute and relative distortion of the lens was measured for the star points whose mean square error of coordinates is 1/71 pixel. The results show that the distortion of the NFOV lens can be measured with high precision and this method can meet space application.
3 GHz analog optical fiber transmission system applied in ultra-fast diagnosis
LIU Fu-hua, AN Yu-ying, WANG Ping, SHAO Bi-bo, FENG Guo-bin
2011, 35(5): 596-599. doi: 10.3969/j.issn.1001-3806.2011.05.006
Abstract:
A broad-bandwidth analog optical fiber transmission system was developed for ultra-fast pulse signal transmission under the circumstance with complicated electromagnetic field. The ultra-fast pulse electric signal was converted to optical signal by means of electro-optic conversion. After several kilometers distance transmission, the optical signal was recovered by means of photo-electric conversion. The experimental measurement results of the system indicate that its bandwidth is (0.0003~3)GHz, in-band flatness is 1dB, linear dynamic range is 40dB(100 multiples), output peak-to-peak noise is less than 5mV, input standing-wave-ratio is less than 2. It's applied in high power microwave experiments. The results show that the 3GHz analog optical fiber transmission system which employs electro-optic and photo-electric conversion technology is suitable for ultra-fast pulse signals transmission in radiation field diagnosis.
Vibration measurement and analysis by means of laser Doppler heterodyne principle
HUO Lei, ZENG Xiao-dong, AN Yu-ying, FENG Zhe-jun, CAO Chang-qing
2011, 35(5): 600-602,687. doi: 10.3969/j.issn.1001-3806.2011.05.007
Abstract:
Laser Doppler measurement methods and coherent heterodyne detection were adopted to measure the frequency and amplitude of low frequency vibration. An experiment setup was built, based on which the Doppler effect was measured with a heterodyne laser interferometer and the standard frequency deviation was obtained. The results shows that the system can detect the object vibration at less than 500Hz frequency, and the measurement standard deviation is less than 5.610-8; The strength of the system detection signal is linear with the amplitude of object, demonstrating that the intensity detection amplitude reduces with the drop of the voltage of the piezoelectric ceramic. The result is helpful to know the characteristics of vibration targets.
Micro-displacement measurement system of pulse equivalent and return difference of stepping motor
, Bitao Hu
2011, 35(5): 603-605.
Abstract:
Abstract: In order to accurately measure the pulse equivalent and return difference of stepping motor, a laser micro-displacement measurement system is proposed based on thin film interference. The system includes He-Ne laser source, the Newton-ring device system, the planar CCD video signal gather system, the computer and data processing software. The measurement of micro-displacement is carried out by counting the fringe numbers with the resolution of 1/400 wavelength. The precision, sensitivity and stability in this system have been improved compared with traditional measurement technique, and the system is particularly suitable for the micron, sub-micron measuring range. The results of measurement with TSA50-C commercial stepping motor show that a displacement accuracy of nanometers scale is achieved in the common laboratorial environment. The results indicate the relative error for less than 5 m displacement of pulse equivalent and return difference. are 2.63% and 0.44% respectively.
Effect of pulse walk-off on femtosecond pulse compression in photonic crystal fibers
ZHAO Rong-xia, LI Ai-ping
2011, 35(5): 606-609. doi: 10.3969/j.issn.1001-3806.2011.05.009
Abstract:
In order to study the influence of pulse walk-off on femtosecond signal pulse compression in photonic crystal fibers, the coupled nonlinear Schrdinger equations were numerically solved by means of standard split-step Fourier method. The nonlinear propagation of two femtosecond optical pulses in a photonic crystal fiber was simulated. The effect of pulse walk-off and asynchronous coupling on signal pulse compression was simulated and analyzed. It is found that the signal pulse can be compressed through the cooperation by group velocity dispersion, third-order dispersion, self-phase modulation and cross-phase modulation, when the pump pulse is input in the anomalous dispersion region while the signal pulse is input in the normal dispersion region. Pulse walk-off not only leads to the degradation of the compression ratio of the signal pulse but also leads to a longer fiber length at which the width of the compressed signal pulse is the minimum, and leads to the non-symmetry of the compressed signal pulse. It is also found that the quality factor of the signal pulse will be improved with the asynchronous coupling method.
Minority carrier lifetime measurement for N-type 4H-SiC by means of the microwave photoconductivity decay method
GAO Dong-mei, LU Qi-rong, WEI Yan-bing, HUANG Bin
2011, 35(5): 610-612,631. doi: 10.3969/j.issn.1001-3806.2011.05.010
Abstract:
In order to understand the electrical property of N-type 4H-SiC better and evaluate its crystal quality, with laser technique and microwave photoconductivity measurement as a tool of the non-conductive and non-destructive characterization for semiconductors, the measurement principle was described and the experimental equipment was put forward. The dependence of the minority carrier lifetime on the excitation intensity was discussed. The results show that the changing of the laser pulse energy (i.e. the photon injection level) little affect the carrier lifetime of the specimen, its peak voltage is proportional to the excitation intensity. The method of carrier lifetime measurement is convenient and efficient and has a great significance for examination of the property of SiC material.
Design of a new laser thickness measurement instrument
XIONG Zhi-yong, ZHAO Bin
2011, 35(5): 613-617. doi: 10.3969/j.issn.1001-3806.2011.05.011
Abstract:
In order to measure the thickness of the hot-rolled steel plate on line, an automatic laser gauging system was established, and its mechanical design and optical design, image algorithm based on MATLAB were investigated. Firstly,the laser beam was inclined to project onto the side of the plate,and a baffle is setted to block the part of light at horizon.Secondly, the laser spot on the tested plate is imaged to CCD target surface in an industrial video camera.Then the defocusing amount is calulated based on the the CCD images.Finally,according to the geometric relationship between actual thickness of the plate to be measured and the imaging height of the plate flank in the CCD and the defocusingamount, the thickness of the steel plate is calculated. Experimental results indicate that the precision of the system is 0.32mm, smaller than the measurement system requirements 0.5mm when the plate thickness between 8mm and 120mm. This measuring system has less influence induced by high temperature radiation.It can satisfy the system requirements of stabilization,higher precision and rapidity,as well as little interference.
Study on phase shift auto-balanced laser absorption spectroscopy
SHU Xiao-wen, ZHANG Yu-jun, GENG Hui, ZHANG Shuai, XU Zhen-yu, ZHANG Liang
2011, 35(5): 618-621,625. doi: 10.3969/j.issn.1001-3806.2011.05.012
Abstract:
Tunable diode laser absorption spectroscopy (TDLAS) is a flexible and well-developed technology used for gas detection in open optical path. In order to improve the detection sensitivity in the direct absorbing method, and solve the adaptation of auto-balanced detection requiring two similar optical paths, a so-called phase shift auto-balanced detection was presented, in which after filtering, amplifying and phase shifting, the absorption signal could be obtained from two optical signals with phase shift difference of 180; and then gas density could be calculated after processing the absorption signal and the direct current indicating the light intensity. The results show that phase shift auto-balanced detection can overcome the disadvantages of the auto-balanced detection for it can not be used in the same optical path. In addition, it is very sensitive to the subtle change of signal and the signal-to-noise ratio is improved greatly, 8~9 times higher than direct detection. The phase shift auto-balanced detection can provide a sensitive and stable approach to detect the long-range gas and may be used in wider areas in the future.
Total reflection through characteristics of light in 1-D doping photonic crystal
LONG Tao, LIU Qi-neng
2011, 35(5): 622-625. doi: 10.3969/j.issn.1001-3806.2011.05.013
Abstract:
In order to study the total reflection through characteristics of light in 1-D doping photonic crystal, the transmissivity of TE wave was calculated by means of the transition matrix method when the incident angle greater than full reflection angle. Total reflection through effect was found in the transmission wave. Response curves of total reflection through effect versus incident angle, impurity thickness, impurity index and period were obtained. These features can be used to design filter of photonic crystal.
Improvement method of measuring object deformation by using double-exposure with gray-level
ZHOU Jian-chao, GONG Ai-ling, DU Yuan
2011, 35(5): 626-628. doi: 10.3969/j.issn.1001-3806.2011.05.014
Abstract:
The usual method for recording and processing hologram images is digital holography, which is also suitable for double-exposure to measuring object deformation. However, the deformation near half of the optical wavelength is based on phase-shift method, and it needs more than three hologram images. In order to simplify the method, the double-exposure with gray-level was extended to measure deformation. By using the gray-level, with the image of gray-level distributions, the fringe numbers can be calculated and then the out-of-plane displacement was obtained. This method only needs take two images. Through theoretical analysis and experimentation, the result is satisfactory, which show this method works well in a certain extent.
Structural design of the water cooling system in a high power end cooled Yb:YAG slab laser
JIANG Xin-ying, ZHENG Jian-gang, YAN Xiong-wei, DUAN Wen-tao, LI Ming-zhong, YU Hai-wu, ZHANG Yong-liang, SHAN Xiao-tong
2011, 35(5): 629-631. doi: 10.3969/j.issn.1001-3806.2011.05.015
Abstract:
In order to achieve a high cooling efficiency of a high power Yb:YAG laser, its water cooling structural was designed, and the heat transfer effect of this structure was simulated by means of finite element method. Surface coefficient of heat transfer and the temperature distribution on the heat exchange surface were obtained. The results indicate that the distribution of the transfer coefficient and the temperature is uniform distribution in this structure. The coefficient of heat transfer reached 1.8104W/(m2K) and the temperature difference on the surface was less than 1K, which indicate a good heat transfer effect.
Wave band effect of solar cells under irradiation of CW laser
QIU Dong-dong, WANG Rui, CHENG Xiang-ai, SUN Yong-jiang
2011, 35(5): 632-635,683. doi: 10.3969/j.issn.1001-3806.2011.05.016
Abstract:
In order to find the wave band effect of solar cells under irradiation of continuous wave(CW) laser, the irradiation effect and damage effect of monocrystalline silicon solar cells were studied under the irradiation of three kinds of in-band or out-of-band CW laser. The response of solar cell to laser was observed. Then, the damage morphology of the cell and the absorption curves of its original material were compared, and the absorption mechanism of solar cells at the wavelengths near the intrinsic absorption long wavelength threshold was obtained. Finally, the reason for different damage results induced by 10.6m laser and 1064nm laser was analyzed. The results show that the great difference between the absorption coefficients of cover glass and silicon at different laser wavelengths is the reason for different damage results to solar cells.
Synthesis of diaza-bridged C60 and its nonlinear optical properties
LI Li, JIA Ruo-ling, LIANG Yu, TANG Guang-shi, LIU Shu-zhi, WANG Zi-qiang
2011, 35(5): 636-638,704. doi: 10.3969/j.issn.1001-3806.2011.05.017
Abstract:
The nonlinear optical property and optical limiting property of a new diaza-bridged C60 derivative were studied by means of z-scan technique and experiment under irradiation of 8ns pulse duration at 532nm. The reverse saturation absorption and nonlinear refraction were observed by means of z-scan technique . The nonlinear absorption coefficient and the value of the third-order nonlinear optical susceptibilities (3) were obtained respectively. The compound had lower value of the optical limiting clamp. All the results show that this compound has a good optical limiting performance.
Model on the chlorophyll, suspended matter and gelbstoff concentrations based on MODIS data
MA Jin-ji, LI Jian, SONG Yao
2011, 35(5): 639-643. doi: 10.3969/j.issn.1001-3806.2011.05.018
Abstract:
In order to establish the mode of the concentration of three elements (chlorophyll-a, suspended matter and gelbstoff), several neural network models were established to retrieve the three element concentration simultaneously from remote sensing reflectance based on moderate-resolution imaging spectroradiometer(MODIS) data. The measured ocean color data was obtained in Pearl River esturay in 2003 and 2004. According to the model, the map of the concentrations of the three elements was drawn and its forming reason was analyzed. The study demonstrates that the model can get the better prediction accuracy based on the reflectance at band combination of 443nm, 488nm, 531nm, 551nm, 667nm, 678nm and 748nm than the other band combinations. The algorithm has good accuracy.
Effect of offing fog on laser transmittance
GAO Wen-jing, DOU Mao-sen, LI Jin-liang, WANG Lei, ZANG Shou-hong
2011, 35(5): 644-647. doi: 10.3969/j.issn.1001-3806.2011.05.019
Abstract:
In order to study the effect of fog on laser transmission, the near-infrared extinction characteristic of fog was analyzed by means of theoretical analysis and experimental measurement. The measurement and simulated data for laser atmosphere transmittance attenuation characteristics were obtained under the same conditions of frog at different visibility. The results show that the fog is the major affecting factor for laser atmosphere transmittance on ocean environment, the extinction coefficient caused by fog is in the order of 10-1km-1 or 100km-1, the attenuation caused by fog is decuple, even several decades times of that caused by the atmosphere molecular scattering and absorption,the extinction caused by fog is more than 85% ratio to the total extinction. The empirical constant C was revised combing the measurement data and the empirical expression of attenuation coefficient at 1.06m laser was obtained at different visibility. The results play important reference role in scientific evaluation of the efficiency of laser countermeasure equipment.
Research of laser guided signal sorting and code recognition technique
SHAO Xiao-dong, YAO Long-hai, ZHANG Shao-kun, WU Shi-jia, LU Hai-xiang, WANG Jing-tian
2011, 35(5): 648-651,655. doi: 10.3969/j.issn.1001-3806.2011.05.020
Abstract:
The pulse interval modulate technique is used in most of the laser semi-active guided weapons, but the known method of code recognition is inefficient because of its repeated calculation and redundant data. To solve this problem, a new code recognition algorithm was presented, in which the last accumulating condition was selected as the current condition so as to decrease repeating work. This algorithm can recognize the type and the bone cycle of coding accurately, and shorten the decoding time, making the real-time accurate recognition of code in embedded system possible. At the end of the paper, a trial which is made to prove the algorithm efficient, tells the algorithm is better than others in time consuming and it can recognize most of the encoding types.
Liquid crystal variable retarder development and electric-control retardation measurement
JIANG Ji-jun, ZHANG Da-yong, LI Jian-feng
2011, 35(5): 652-655. doi: 10.3969/j.issn.1001-3806.2011.05.021
Abstract:
In order to get linearly-controlled variable retarder, a liquid crystal variable retarder(LCVR) was developed based on SLC-7607A parallel nematic liquid crystal. Its operating principle and technology was described. New method measuring retardation of the variable retarder based on Stokes parameters was put forward, and the characteristic curve describing relationship of retardation and voltage was well reproducibly drawn. Experimental result indicates that retardation is inversely proportional to the applied voltage ranging from 1V to 2.7V, and the fitted linear relation is achieved. The obtained result attributes to the development, measurement and application of LCVRs.
Multiplexed communication based on a chaotic system with multiple signal-modulation delay optical feedback
KE Qiang, WANG Yi-fan, HU Ju-ju
2011, 35(5): 656-658,663. doi: 10.3969/j.issn.1001-3806.2011.05.022
Abstract:
To investigate the multiplexed communication in a chaos system with semiconductors subject to optical feedback and optical injection where delays are modulated by signals, the encryption is realized through modulating the channel delay with the corresponding user's signal and the decryption is implemented utilizing chaos synchronization and cross correlation measurement by numerical simulation. The multiplexing and de-multiplexing of three user's signals of 1Gbit/s were realized. Also, the conditions for efficient decryption and the main factors affecting bit error were analyzed.
Propagation properties of Gaussian beams passing through cat-eye optical system with misaligned lens
TANG Rui, SHEN Xue-ju, HAN Yu-dong
2011, 35(5): 659-663. doi: 10.3969/j.issn.1001-3806.2011.05.023
Abstract:
To analyze the influence of misaligned parameters of lenses on reflection properties of Gaussian beam, an approximate analytical expression of the output field distribution for Gaussian beam passing through a misaligned optical system with misaligned lenses were derived using approximate expression of the hard-edge ellipse aperture function and generalized diffraction formula. The result shows that influence of transverse displacement of a lens on the property of reflection beam is more notable than angle displacement. This method is helpful for the analysis of the transmission property of Gaussian beams.
Effects of infra-red rays on blood lipid in rats and blood glucose in mice
ZHANG Ya-mei, LI Bin, PANG Xiao-feng
2011, 35(5): 664-666,695. doi: 10.3969/j.issn.1001-3806.2011.05.024
Abstract:
Infra-red ray can regulate the nervous system and endocrine system, promote metabolism and protein synthesis, speedup blood circulation to improve microcirculation. To explore the effects of exposing rats to infra-red on hyperlipemia and hyperglycemia, the hyperlipemia rat models and hyperglycemia mouse models were established. After Infrared rays irradiation, the levels of blood lipid in rats, the levels of blood glucose in mice, superoxide dismutase(SOD) activity and malondialdehyde(MDA) content in serum were measured. The results show that Infrared rays improves the blood circulation, the levels of blood lipid in hyperlipemia rats (P0.01) and blood glucose in hyperglycemia mice (P0.05) are significantly decreased, the SOD activity is enhanced and the serum of hyperlipemia rats and hyperglycemia mice is decreased by MDA content. However, there are few changes in the normal mice exposed to Infrared ray. These results indicate that Infrared ray is favorable to preventing the hyperlipemia and hyperglycemia.
Comparison of electro-optic deflectors of different geometric configurations
LU Zhi-yong, WAN Ling-yu, MA Xue-mei, WANG Rong-cheng
2011, 35(5): 667-671. doi: 10.3969/j.issn.1001-3806.2011.05.025
Abstract:
For the development of fine electro-optic deflectors, an equivalent expression of refractive index gradient in a deflector of cascade crystal prisms was analyzed under the condition of paraxial approximation. Equations of the deflection angle and ray trajectory of an electro-optic deflector with different geometric constructions were summarized and their deflection characteristics were studied by means of numerical analysis. Deflection sensitivities of trapezoidal, horn and parabola shaped deflectors were compared with each other. It is helpful for the design of electro-optic scanners with big deflection angles.
Raman spectrum analysis of forsythia leaves
WANG Wei, XI Xin-xin, WANG Bei, LI Jian-bo, JING Heng-cui
2011, 35(5): 672-674. doi: 10.3969/j.issn.1001-3806.2011.05.026
Abstract:
In order to assess the quality of the forsythia leaves gathered in different periods rapidly, their Raman spectra were obtained with RM-1000 confocal microscopy laser Raman spectrometer, then the specific peaks of their Raman spectra were obtained after analysis and experiments. The Raman spectra of forsythia leaves show the main characteristic peaks are mainly in the range of 700cm-11600cm-1 and 2600cm-13100cm-1. The characteristic peaks are closely related with forsythin which is considered as the main active ingredient in the forsythia leaves and can be used for qualitative identification. The peak intensity in the spectra of forsythia leaves gathered in different periods is significantly different so that the quality of forsythia leaves can be evaluated. Raman spectra can be used for qualitative identification and evaluation of forsythia Leaves and it is direct, fast, simple and accurate. The results are useful for quality control of the traditional Chinese medicine.
Determination of optical coefficients of biological tissue by means of diffuse image
ZHANG Lian-shun, ZHANG Xiao-hui, WANG Zhang-zhen
2011, 35(5): 675-677. doi: 10.3969/j.issn.1001-3806.2011.05.027
Abstract:
In order to acquire the optical properties (scattering and absorption coefficients) of biological tissue, the CCD non-invasive measurement equipment was used to measure the image of diffuse reflectance of biologrcal tissue. The spatially resolved diffuse reflectance of the tissue was acquired by analyzing the image. One set of experimental data on tissue phantoms were used to train a neural network which was used to extract the optical properties. The accuracy of the neural network was investigated and validated by another set of experimental data. The optical properties of bovine muscle, pig muscle and human skin tissue under 633nm laser irradiation were also determined by the network which was trained by the experiment. The result shows the neural network can estimate the optical properties of different tissues with high accuracy.
Identification for Wuliangye wine with fluorescent feature parameters
SHI Yuan-ping, ZHU Tuo, CHEN Guo-qing, GAO Shu-mei, ZHENG Lei, MA Chao-qun
2011, 35(5): 684-687. doi: 10.3969/j.issn.1001-3806.2011.05.029
Abstract:
In order to achieve the application of fluorescent spectroscopy in the detection and identification of liquor, the three-dimension fluorescent spectrograms of Wuliangye wine and some common liquor such as Maotaichun and Gaogou, were drafted through the detection of their fluorescent spectra. These spectrograms show that the three-dimension fluorescent spectrogram of Wuliangye is distinct from those of the common liquors but similar to that of Maotaichun. To distinguish Wuliangye from other samples, firstly the characteristic parameters were extracted from its fluorescent spectra, and then those parameters were classified by the aid of least-squares support vector machine. Thus Wuliangye was distinguished from other liquors. The result indicates that the extracted characteristic parameters of fluorescent spectra can be used to identify Wuliangye, and the process of extraction is completed by computer, which improves the efficiency of identification. This method can be applied to identify other liquors and provide a more practical and effective way for liquor identification.
Analysis of frequency response of segment electrodes in integrated optical waveguide electric field sensors
HU Zhe-feng, CHEN Fu-shen, SUN Bao, CHEN Shi
2011, 35(5): 688-691. doi: 10.3969/j.issn.1001-3806.2011.05.030
Abstract:
In order to study the frequency response characteristics of segment electrodes in an integrated optical waveguide electric field sensor, they were calculated by means of finite difference time domain method, and were measured in the actual gigahertz transverse electromagnetic wave(GTEM)cell. The results show that, when the segments number is 10 and the total length of electrodes decreases from 42mm to 12mm, the responding frequency bandwidth increases from 2.68GHz to 5.91GHz; when the total length of electrodes is 42mm and the segment number increases from 10 to 30, the bandwidth of responding frequency decreases slightly from 2.68GHz to 2.51GHz. The simulated results are consistent with measurement results.
Research for temperature distribution characteristics of the fiber in a Bragg fiber laser
CHEN Hai-tao, YANG Hua-jun, RONG Jian, CHENG Xiao-hong
2011, 35(5): 692-695. doi: 10.3969/j.issn.1001-3806.2011.05.031
Abstract:
In order to study the temperature property of the fiber in a Bragg fiber laser, the steady thermal model was presented. The temperature distribution was analyzed based on heat transfer equations. The temperature distribution and the thermally-induced stress in the fiber were simulated by means of numerical finite-element method. Effects of thermal power density, number of cladding layers and environmental convection coefficient on the temperature distribution were discussed. The results show that the temperature of coating is much lower than its critical temperature 300℃, and the temperature difference between the core and coating is only about 10℃. The result of analysis is helpful to the design of Bragg fiber lasers.
Analysis of phase-contrast method with background light
YANG Heng, HUANG Zuo-hua, LIU Yun
2011, 35(5): 696-698. doi: 10.3969/j.issn.1001-3806.2011.05.032
Abstract:
In order to observe weak phase objects, the phase contrast imaging of any phase objects with background light was strictly analyzed by mathematics. The general expressions of the image intensity, the best phase shift and the best transmittance of a phase plate were obtained. If the images are received by CCD, the phase variation of phase object that can be tested is about 1.9mrad. These will provide the mathematical demonstration for observing and testing weak phase objects.
Multifunction protection goggles against laser radiation
LUO Zhen-kun, WANG Qiu-hua, GAO Guang-huang, SUN Rang, ZHANG Gui-su, CHEN Zong-li
2011, 35(5): 699-704. doi: 10.3969/j.issn.1001-3806.2011.05.033
Abstract:
In order to reduce and avoid damage form laser and microwave, multifunction protection goggles, incorporating protective systems against laser and microwave and an integrated warning system was developed. The goggles consist of some optical parts and photoelectron modules that perform a specific function, which include multifunction protective lenses, frames and laser detection-alarm systems. The key compounded technologies of multifunction protection were studied and protective performance of the spectacles was tested. The result shows that the optical density of this goggles is from 4.0 to 7.28 at the laser wavelength of 532nm, 1064nm,790nm and 840nm; integral transmittance of visible light is 18.7%; attenuation value of microwave radiation is more than 20dB; the warning system can provides an automatic detecting and sound-light warning at the laser wavelength of 532nm, 1064nm and 840nm; detecting sensitivity of alarm is 10-7J/cm2; this goggles can resist impact against steel-ball splinter whose mass is 1g, speed between 300m/s and 400m/s; gross weight of the goggles is less than 200g. In addition, the spectacles have characteristics of wide range of protection wavelength, higher attenuation rate for laser and microwave, bigger protection angle, higher transmittance for visible light, usage of separated type and combined type, smaller size, light-weight and convenience to wear. They not only can protect an individual operator against laser and microwave radiation, but also can protect photo-electric sensors. They are also necessary protection equipment in modern optical experiment as well as terrorism opposition and public safety.
Effect of dispersion and nonlinearity on performance of asynchronous OCDMA systems
ZENG Ren-fen, WANG Ying-lian
2011, 35(5): 705-707,711. doi: 10.3969/j.issn.1001-3806.2011.05.034
Abstract:
In order to study the influence of dispersion and nonlinearity on asynchronous optic code division multiple access(OCDMA)systems based on nonlinear Schrdinger equation, the functions of the bit error rate of an asynchronous OCDMA system with the transmission distance and the number of users were obtained by means of simulation. The results show that the performance of an asynchronous OCDMA system can be deteriorated severely by the group velocity dispersion, the third-order dispersion and nonlinear effects, especially the group velocity dispersion. Dispersed shift fiber can be used as system transmission medium so as to compensate the consequent system performance degradation.
Research of PMMA etched by KrF excimer laser
MA Mei-juan, ZHANG Yun-hai, MAN Bao-yuan
2011, 35(5): 708-711. doi: 10.3969/j.issn.1001-3806.2011.05.035
Abstract:
In order to research the internal mechanism of interaction between excimer laser and polymethylmethacrylate(PMMA ), the surface of PMMA was vertically irradiated by KrF excimer laser at wavelength of 248nm, and the experiment was completed in atmosphere through changing laser energy and pulse number. The treated PMMA was analyzed with many methods, for example scanning electron microscope(SEM), X-ray photoelectron spectroscopy(XPS), etc. The results of SEM indicate that a lot of apertures can appear at the irradiated surface of PMMA. The phenomenon means that some gas is given out when excimer laser irradiates PMMA. The results of XPS show that peak intensity of C1s decreases but peak intensity of O1s increases, so the methyls of PMMA are etched and O2 in atmosphere attends the reaction. Besides, the research on the etching rate and the roughness indicates they do not always increase when laser energy and pulse number increase.
Preparation and properties of Yb3+-doped silicate laser glass
DONG Gao-ming, HOU Lan-tian, HUANG Gang, HU Hui-jun, ZHOU Gui-yao
2011, 35(5): 712-714. doi: 10.3969/j.issn.1001-3806.2011.05.036
Abstract:
In order to prepare Yb3+-doped silicate laser glass and analyze its laser characteristics, based on the no-chemical vapor deposition high temperature melting process in an oxygen-enriched atmosphere, the data of the absorption and fluorescence spectra of the glass were obtained according to Fuchbauer-Ladenburger(F-L) method. It can be concluded that there are board-band absorption peaks in the absorption band of 850nm~1100nm near-infrared wavelengths. The main absorption peak is at 978nm and the sub-peak value is at 919nm respectively, the main fluorescent peak is at 1018nm with the sub-peak value at 970nm. The integrated absorption cross section, stimulated emission cross section and fluorescent lifetime of Yb3+ were calculated theoretically. This result is useful to characteristic analysis of silicate laser glass. The comprehensive test results show that they can meet the application requirements of laser glass.
Measurement of complete Stokes parameters of 2-D polarized light
FENG Wei-wei, MA Guo-li, JIA Tian-jun, CHENG Xiang, CHEN Li-gang
2011, 35(5): 715-717. doi: 10.3969/j.issn.1001-3806.2011.05.037
Abstract:
In order to measure the complete Stokes parameters of the target accurately, the effect of systematic disturbance on the measurement accuracy was analyzed based on the numerical simulation method of 2-norm condition number of measurement matrices and verified in experiments. Simulation study shows that the measuring system can run optimally and effectively when the angles of the fast axis of the /4 wave-plate are appropriate combination angles (i.e., 13, 50, 128, 164).
Application and development of laser technology in BPH
YU Xiao-min
2011, 35(5): 718-720. doi: 10.3969/j.issn.1001-3806.2011.05.038
Abstract:
First of all, the development in the treatment of benign prostatic hyperplasia(BPH) was introduced. Then the principle of laser vaporesection was explained. Several new methods, characteristics were introduced and compared, such as KTP green light, 2m continuous wave laser and diode laser. Finally, it was prospected that laser vaporesection might be the potential new technology to replace the traditional surgery in the treatment of BPH.