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RSS2009 Vol. 33, No. 6
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2009, 33(6): 561-564.
doi: 10.3969/j.issn.1001-3806.2009.06.001
[Abstract]
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Abstract:
The surface-charges of cells are very important to study the vital characteristic of cells.Common methods only measure the changes of cell electrophoresis mobility (EPM) instead of the quantity of cell surface-charges.In order to measure the surface-charges of cells,a novel method to measure the surface-charges of cells by means of optical tweezers and electrophoresis in a microchannel was designed.With this method,the quantity of the electric charge of yeast cells was measured about 10-10℃.Experimental results prove that this method can be used to measure the changes of cell surface-charges.A lab-onchip (LOC) for measuring the surface-charge of cells might be developed after improving this measuring system.
The surface-charges of cells are very important to study the vital characteristic of cells.Common methods only measure the changes of cell electrophoresis mobility (EPM) instead of the quantity of cell surface-charges.In order to measure the surface-charges of cells,a novel method to measure the surface-charges of cells by means of optical tweezers and electrophoresis in a microchannel was designed.With this method,the quantity of the electric charge of yeast cells was measured about 10-10℃.Experimental results prove that this method can be used to measure the changes of cell surface-charges.A lab-onchip (LOC) for measuring the surface-charge of cells might be developed after improving this measuring system.
2009, 33(6): 565-567,578.
doi: 10.3969/j.issn.1001-3806.2009.06.002
Abstract:
In order to measure the tuning wavelength of a frequency-doubled Nd:YAG laser,strong absorption lines of molecular iodine near 532nm was adopted to provide the absolute reference for frequency stabilization.The experiment system for measuring wavelength was built up with iodine vapor as reference,and the iodine vapor absorption lines were measured.Compared with the computed absorption lines,the relations between laser tuning frequency and voltage,laser tuning frequency and rotary angle of potentiometer were obtained,the mode hop was found,and the tuning range of frequency-doubled Nd:YAG laser was measured.The results show that it is a suitable method for measuring tuning wavelength of frequency-doubled Nd:YAG laser by means of iodine vapor absorption lines.
In order to measure the tuning wavelength of a frequency-doubled Nd:YAG laser,strong absorption lines of molecular iodine near 532nm was adopted to provide the absolute reference for frequency stabilization.The experiment system for measuring wavelength was built up with iodine vapor as reference,and the iodine vapor absorption lines were measured.Compared with the computed absorption lines,the relations between laser tuning frequency and voltage,laser tuning frequency and rotary angle of potentiometer were obtained,the mode hop was found,and the tuning range of frequency-doubled Nd:YAG laser was measured.The results show that it is a suitable method for measuring tuning wavelength of frequency-doubled Nd:YAG laser by means of iodine vapor absorption lines.
2009, 33(6): 568-570.
doi: 10.3969/j.issn.1001-3806.2009.06.003
Abstract:
In order to measure the powder flow,a measurement system of powder flow in laser remanufacturing technology was designed.The variance of the powder flow was detected with a capacitance sensor and with 2Cr13 and H13 metal powder as transmission medium,experiments were carried out.The results show that a smaller solution can be obtained if the change of powder density is larger than 10-1g/min with H13 metal powder as medium.The system can be used to measure powder flow.
In order to measure the powder flow,a measurement system of powder flow in laser remanufacturing technology was designed.The variance of the powder flow was detected with a capacitance sensor and with 2Cr13 and H13 metal powder as transmission medium,experiments were carried out.The results show that a smaller solution can be obtained if the change of powder density is larger than 10-1g/min with H13 metal powder as medium.The system can be used to measure powder flow.
2009, 33(6): 571-574.
doi: 10.3969/j.issn.1001-3806.2009.06.004
Abstract:
In order to measure the phase modulation characteristics of type LC-R2500,made by Germany HOLOEY company,the relationship between image gray and phase shift was obtained based on double-slit interference.The image encoded by phase retrieval algorithm was input to spatial light modulator,theoretical analysis and experimental research were deployed.Experimental results show the optical reconstructed image is conformal to the numerical reconstructed image,which proves the veracity of measurement of phase modulation characteristics.
In order to measure the phase modulation characteristics of type LC-R2500,made by Germany HOLOEY company,the relationship between image gray and phase shift was obtained based on double-slit interference.The image encoded by phase retrieval algorithm was input to spatial light modulator,theoretical analysis and experimental research were deployed.Experimental results show the optical reconstructed image is conformal to the numerical reconstructed image,which proves the veracity of measurement of phase modulation characteristics.
2009, 33(6): 575-578.
doi: 10.3969/j.issn.1001-3806.2009.06.005
Abstract:
In order to measure the rail linearity accurately,an embedded laser detection system,composed of image acquisition and transmission module,image processing and data-processing module,laser range module,was designed based on autocollimation theory.After a series of image processing,the images and distance parameters were sent to the autocollimation algorithm,and the rail linearity offset can be obtained with a measuring accuracy of 0.3 mm.The system can replace the traditional manner of rail detection,also make the detection process more simple and accurate.
In order to measure the rail linearity accurately,an embedded laser detection system,composed of image acquisition and transmission module,image processing and data-processing module,laser range module,was designed based on autocollimation theory.After a series of image processing,the images and distance parameters were sent to the autocollimation algorithm,and the rail linearity offset can be obtained with a measuring accuracy of 0.3 mm.The system can replace the traditional manner of rail detection,also make the detection process more simple and accurate.
2009, 33(6): 579-581.
doi: 10.3969/j.issn.1001-3806.2009.06.006
Abstract:
In order to obtain high-quality KMgF3 crystal,it was grown by Czochralski method in the CF4 atmosphere.The volatiles and remainders of the crystal growth were analyzed,and the infrared transmission spectrum of the crystals was measured.The main volatile matter is KF,and there is MgF2 phase in the remainders while crystallization rate is high.In the infrared transmission spectrum there is no OH- absorption,but COH absorption is obvious.Above results display that CF4 atmosphere is favorable for eliminating oxygen source of the growth atmosphere,such as H20 etc.To get high quality KMgF3 crystal,it is not negligible to inhibit the volatility of KF effectively and to replenish KF suitably in the crystal growth.
In order to obtain high-quality KMgF3 crystal,it was grown by Czochralski method in the CF4 atmosphere.The volatiles and remainders of the crystal growth were analyzed,and the infrared transmission spectrum of the crystals was measured.The main volatile matter is KF,and there is MgF2 phase in the remainders while crystallization rate is high.In the infrared transmission spectrum there is no OH- absorption,but COH absorption is obvious.Above results display that CF4 atmosphere is favorable for eliminating oxygen source of the growth atmosphere,such as H20 etc.To get high quality KMgF3 crystal,it is not negligible to inhibit the volatility of KF effectively and to replenish KF suitably in the crystal growth.
2009, 33(6): 582-585,589.
doi: 10.3969/j.issn.1001-3806.2009.06.007
Abstract:
In order to process conveniently speckle images in speckles measurement,a simple system of electronic speckle pattern interferometry images processing was designed by means of LabVIEW and MATLAB.In this method,LabVIEW was used to design display interface and the powerful image processing functions of MATLAB were invoked to process speckle images.The experimental result shows that the contrast of fringes can be increased by the proposed method.
In order to process conveniently speckle images in speckles measurement,a simple system of electronic speckle pattern interferometry images processing was designed by means of LabVIEW and MATLAB.In this method,LabVIEW was used to design display interface and the powerful image processing functions of MATLAB were invoked to process speckle images.The experimental result shows that the contrast of fringes can be increased by the proposed method.
2009, 33(6): 586-589.
doi: 10.3969/j.issn.1001-3806.2009.06.008
Abstract:
The effect of laser transformation hardening on the surface property and microstructure of mild steel 10CrNiMo under different laser power and cooling conditions was studied.A hardened layer on the surface of the mild steel was obtained whose microhardness is 100HV～150HV higher than that of the original mild steel The microstructure of laser processed zone was observed with a metallographic microscope and the hardness of laser processed layer was measured with a microhardness tester.The results showed that the quench zone consisted of martensite,retained sorbite,troostite,tempered sorbite and that the microstrcture in the lap zone was martensite and some sorbites locating in the middle of martensite.Because of the lower carbon content of steel 10CrNiMo and different carbon diffusion coefficient,the highest hardness did not appear on the surface but in the subsurface.In the softened zone,because the martensite produced by the first laser scanning was tempered by the second laser beam,the carbon in the martensite separates and changes into temper sorbite.Microhardness of lap zone declined due to the temper of second laser scanning.Laser transformation hardening can improve the surface hardness 100HV～150HV higher and keep good tenacity.Furthermore,laser cladding can be taken to increase the hardness more evidently.
The effect of laser transformation hardening on the surface property and microstructure of mild steel 10CrNiMo under different laser power and cooling conditions was studied.A hardened layer on the surface of the mild steel was obtained whose microhardness is 100HV～150HV higher than that of the original mild steel The microstructure of laser processed zone was observed with a metallographic microscope and the hardness of laser processed layer was measured with a microhardness tester.The results showed that the quench zone consisted of martensite,retained sorbite,troostite,tempered sorbite and that the microstrcture in the lap zone was martensite and some sorbites locating in the middle of martensite.Because of the lower carbon content of steel 10CrNiMo and different carbon diffusion coefficient,the highest hardness did not appear on the surface but in the subsurface.In the softened zone,because the martensite produced by the first laser scanning was tempered by the second laser beam,the carbon in the martensite separates and changes into temper sorbite.Microhardness of lap zone declined due to the temper of second laser scanning.Laser transformation hardening can improve the surface hardness 100HV～150HV higher and keep good tenacity.Furthermore,laser cladding can be taken to increase the hardness more evidently.
2009, 33(6): 590-592,596.
doi: 10.3969/j.issn.1001-3806.2009.06.009
Abstract:
The absorption characteristics of polyaryl amide-fibers/epoxy and carbon-fibers/epoxy composite radiated by continuous wave laser beam at of 1.319μm were obtained by means of double integrating spheres-photodiode system and microanalysis of recovery specimen.When laser power intensity increases before composite ablation,the absorptive of both the composites slowly decreases.It changes from 0.6 to 0.55 for polyaryl amide-fibers/epoxy composite and from 0.85 to 0.8 for carbon-fibers/epoxy composite.When ablation appears on the composite,the absorptivity of polyaryl amide-fibers/epoxy composite rapidly increases.However,it change little for carbon-fibers/epoxy composite.The results show that ablation has obvious effect on the absorption characteristics of polyaryl amide-fibers/epoxy composite and has little effect on carbon-fibers/epoxy composite.
The absorption characteristics of polyaryl amide-fibers/epoxy and carbon-fibers/epoxy composite radiated by continuous wave laser beam at of 1.319μm were obtained by means of double integrating spheres-photodiode system and microanalysis of recovery specimen.When laser power intensity increases before composite ablation,the absorptive of both the composites slowly decreases.It changes from 0.6 to 0.55 for polyaryl amide-fibers/epoxy composite and from 0.85 to 0.8 for carbon-fibers/epoxy composite.When ablation appears on the composite,the absorptivity of polyaryl amide-fibers/epoxy composite rapidly increases.However,it change little for carbon-fibers/epoxy composite.The results show that ablation has obvious effect on the absorption characteristics of polyaryl amide-fibers/epoxy composite and has little effect on carbon-fibers/epoxy composite.
2009, 33(6): 593-596.
doi: 10.3969/j.issn.1001-3806.2009.06.010
Abstract:
In order to improve the property of stainless steel welding,a rotary double-focus laser-tungsten inert gas (TIG) hybrid welding technique was proposed,in which the rotary double-laser beam and the TIG arc were applied in welding at the same time.The rotary double-focus laser-TIG hybrid welding torch was designed,and a detailed experiment of rotary double-focus laser-TIG hybrid welding on the 304# stainless steel plate with different welding parameters was carried out.The results showed that the hybrid function between the double-focus laser and arc was the main factors affecting the microstructure of welded joint,and that the rotation frequency affected the mierostructure and micro-hardness of welded joint,the lower the rotary frequency,the higher the hardness because of smaller microstructure induced by re-melting of the welding line.The results are applicable in theoretical analysis and experimental research of laser-TIG hybrid welding technique.
In order to improve the property of stainless steel welding,a rotary double-focus laser-tungsten inert gas (TIG) hybrid welding technique was proposed,in which the rotary double-laser beam and the TIG arc were applied in welding at the same time.The rotary double-focus laser-TIG hybrid welding torch was designed,and a detailed experiment of rotary double-focus laser-TIG hybrid welding on the 304# stainless steel plate with different welding parameters was carried out.The results showed that the hybrid function between the double-focus laser and arc was the main factors affecting the microstructure of welded joint,and that the rotation frequency affected the mierostructure and micro-hardness of welded joint,the lower the rotary frequency,the higher the hardness because of smaller microstructure induced by re-melting of the welding line.The results are applicable in theoretical analysis and experimental research of laser-TIG hybrid welding technique.
2009, 33(6): 597-599,603.
doi: 10.3969/j.issn.1001-3806.2009.06.011
Abstract:
Multi-pulse position modulation (MPPM) is more effective than pulse position modulation (PPM) in underwater laser communication due to its advantages of high efficiency and low bandwidth.In order to study the effect of imperfect slot synchronization on bit error of MPPM in underwater laser communication,a method of MPPM map table with the smallest bit error rate was put forward after analyzing MPPM performance with imperfect slot synchronization performance is analyzed.Bit error rate of MPPM based on binary code was compared with that based on Gray code by means of simulation.The result showed that bit error rate of Gray code was lower than that of binary code at the same bandwidth and transmit rate with the bit error rate declined about 2.4dB.The obtained results are theoretic reference to the improvement of the performance of underwater laser communication.
Multi-pulse position modulation (MPPM) is more effective than pulse position modulation (PPM) in underwater laser communication due to its advantages of high efficiency and low bandwidth.In order to study the effect of imperfect slot synchronization on bit error of MPPM in underwater laser communication,a method of MPPM map table with the smallest bit error rate was put forward after analyzing MPPM performance with imperfect slot synchronization performance is analyzed.Bit error rate of MPPM based on binary code was compared with that based on Gray code by means of simulation.The result showed that bit error rate of Gray code was lower than that of binary code at the same bandwidth and transmit rate with the bit error rate declined about 2.4dB.The obtained results are theoretic reference to the improvement of the performance of underwater laser communication.
2009, 33(6): 600-603.
doi: 10.3969/j.issn.1001-3806.2009.06.012
Abstract:
In order to study the properties of fiber laser and coherent combining beam accurately,the propagation properties and beam quality of LP01 mode and the field of coherent combining beam were analyzed in terms of the method that the mode of LP01 was decomposed into orthonormal Laguerre-Gaussian modes.Then the beam quality and the propagation field were compared with that of Gaussian beam which is usually used to describe fiber laser.The results show the far field distribution of LP01 mode and that of Gaussian beam are much different after transmission though their initial field distribution is the same,and the difference between the field of coherent combination of LP01 mode and that of Gaussian beam is obvious.For accurate analysis of the properties of coherent beam combination,the expression of the Laguerre-Gaussian modes of a fiber laser should be used.
In order to study the properties of fiber laser and coherent combining beam accurately,the propagation properties and beam quality of LP01 mode and the field of coherent combining beam were analyzed in terms of the method that the mode of LP01 was decomposed into orthonormal Laguerre-Gaussian modes.Then the beam quality and the propagation field were compared with that of Gaussian beam which is usually used to describe fiber laser.The results show the far field distribution of LP01 mode and that of Gaussian beam are much different after transmission though their initial field distribution is the same,and the difference between the field of coherent combination of LP01 mode and that of Gaussian beam is obvious.For accurate analysis of the properties of coherent beam combination,the expression of the Laguerre-Gaussian modes of a fiber laser should be used.
2009, 33(6): 604-606.
doi: 10.3969/j.issn.1001-3806.2009.06.013
Abstract:
In order to study the performance of low density parity check (LDPC) codes applied in an underwater laser communication system,its bit error rate was simulated by means of soft-decision decoding algorithm.A model of underwater laser communication channel was introduced,and then the encoding and decoding algorithm of LDPC codes was studied.For a certain code length and modulation order,the bit error rate can be reduced to 10-5 with the signal photon number ns increase.The simulation results show that the bit error rate of the system can be improved obviously by means of LDPC soft-decision decoding based on the output soft information of the photo detector.
In order to study the performance of low density parity check (LDPC) codes applied in an underwater laser communication system,its bit error rate was simulated by means of soft-decision decoding algorithm.A model of underwater laser communication channel was introduced,and then the encoding and decoding algorithm of LDPC codes was studied.For a certain code length and modulation order,the bit error rate can be reduced to 10-5 with the signal photon number ns increase.The simulation results show that the bit error rate of the system can be improved obviously by means of LDPC soft-decision decoding based on the output soft information of the photo detector.
2009, 33(6): 607-610.
doi: 10.3969/j.issn.1001-3806.2009.06.014
Abstract:
In order to obtain round texturing craters to improve the uniformity and mechanical properties of the steel sheets with elliptical texturing craters produced by traditional single-head laser texturing technology,a multi-heads laser texturing equipment using rotating polygon as scanning beam splitter and modulator is proposed.Under a certain defocusing condition,the focusing point will move along the roll surface in phase with the rotating speed of the cold roll,so that an approximate round crater with a minimal elliptical ratio (ratio of long axis to short axis) of 1.0010957:1 can be obtained in theory.Some experiments were conducted.The experiment results conform to those calculation ones.By controlling defocusing and other texturing parameters,different elliptical ratio can be designed guiding the application of multi-head laser texturing technique.
In order to obtain round texturing craters to improve the uniformity and mechanical properties of the steel sheets with elliptical texturing craters produced by traditional single-head laser texturing technology,a multi-heads laser texturing equipment using rotating polygon as scanning beam splitter and modulator is proposed.Under a certain defocusing condition,the focusing point will move along the roll surface in phase with the rotating speed of the cold roll,so that an approximate round crater with a minimal elliptical ratio (ratio of long axis to short axis) of 1.0010957:1 can be obtained in theory.Some experiments were conducted.The experiment results conform to those calculation ones.By controlling defocusing and other texturing parameters,different elliptical ratio can be designed guiding the application of multi-head laser texturing technique.
2009, 33(6): 611-614,618.
doi: 10.3969/j.issn.1001-3806.2009.06.015
Abstract:
In order to study the distribution of spontaneous noise in a Yb3+ -doped fiber amplifier (YDFA),the power gain characteristics of amplified spontaneous emission under conditions of different pump schemes and power,end surface reflectivity and spectral filter were studied by solving the discrete rate equation.The results show that the power of amplified spontaneous emission is different under different boundary conditions,and that the power amplification of the amplified spontaneous emission can be suppressed effectively by reducing the fiber surface reflectivity and using a properly selected spectral filter.
In order to study the distribution of spontaneous noise in a Yb3+ -doped fiber amplifier (YDFA),the power gain characteristics of amplified spontaneous emission under conditions of different pump schemes and power,end surface reflectivity and spectral filter were studied by solving the discrete rate equation.The results show that the power of amplified spontaneous emission is different under different boundary conditions,and that the power amplification of the amplified spontaneous emission can be suppressed effectively by reducing the fiber surface reflectivity and using a properly selected spectral filter.
2009, 33(6): 615-618.
doi: 10.3969/j.issn.1001-3806.2009.06.016
Abstract:
In order to study the characteristics of 2-D photonic crystal constructed with two different medium rods,a triangular lattice photonic crystal constructed with layer medium rods/bottom medium and air rods/bottom medium was studied.By means of finite difference time domain method the curves of transmission coefficients versus incident frequencies under different conditions were obtained.The calculated results showed that a wide gap from low to high frequency appeared in the composite photonic crystal,so the electromagnetic wave could be prohibited in a wide frequency range.The further study showed the width of band gap was influenced by the external radius of layer medium rods,while defect mode in the band gap was greatly influenced by the internal radius,dielectric constant and middle layer's dielectric constant.In fact,it is possible to produce very narrow-band optical filters and switches by regulating the photonic crystal structure parameters.
In order to study the characteristics of 2-D photonic crystal constructed with two different medium rods,a triangular lattice photonic crystal constructed with layer medium rods/bottom medium and air rods/bottom medium was studied.By means of finite difference time domain method the curves of transmission coefficients versus incident frequencies under different conditions were obtained.The calculated results showed that a wide gap from low to high frequency appeared in the composite photonic crystal,so the electromagnetic wave could be prohibited in a wide frequency range.The further study showed the width of band gap was influenced by the external radius of layer medium rods,while defect mode in the band gap was greatly influenced by the internal radius,dielectric constant and middle layer's dielectric constant.In fact,it is possible to produce very narrow-band optical filters and switches by regulating the photonic crystal structure parameters.
2009, 33(6): 619-621,625.
doi: 10.3969/j.issn.1001-3806.2009.06.017
Abstract:
In order to achieve high quality and high brightness electron beam,a photocathode injector is used as the electron source in the experimental setup of a free electron laser (FEL).The drive laser system is a master oscillator power amplifier configuration,consisting of a confinuous wave diode-pumped mode-locked oscillator,one double-pass and two single-pass regenerative diode-pumped pulse amplifiers and a four fold frequency conversion part.After adjustment,single micropulse energy of 4μJ with less than 3 percent of jitter at wavelength 266nm was obtained.These micropulses were contained within a macropulse envelope as long as 2μs to 6μs.In the experiments,adopting C2Te photocathode as the photoinjector,more than 40A electron beam was obtained,meeting the requirement of beam current for the FEL.
In order to achieve high quality and high brightness electron beam,a photocathode injector is used as the electron source in the experimental setup of a free electron laser (FEL).The drive laser system is a master oscillator power amplifier configuration,consisting of a confinuous wave diode-pumped mode-locked oscillator,one double-pass and two single-pass regenerative diode-pumped pulse amplifiers and a four fold frequency conversion part.After adjustment,single micropulse energy of 4μJ with less than 3 percent of jitter at wavelength 266nm was obtained.These micropulses were contained within a macropulse envelope as long as 2μs to 6μs.In the experiments,adopting C2Te photocathode as the photoinjector,more than 40A electron beam was obtained,meeting the requirement of beam current for the FEL.
2009, 33(6): 622-625.
doi: 10.3969/j.issn.1001-3806.2009.06.018
Abstract:
There are three absorptivity models,i.e.the single constant absorptivity model,assembled constant absorptivity model whose liquid-state and solid-state absorptivity are both constant and temperature-dependent absorptivity models.In order to compare the influences of the three models on the numerical results,a spatial axis-symmetric finite element calculation model was established based on the three absorptivity models respectively.The laser heating process of an aluminum plate was simulated and the three numerical results were compared.The advantages and disadvantages and the application scope of the three absorptivity models were discussed.The results show that for the heating process of both solid state and liquid state existing evidently,the computed results based on the assembled constant absorptivity model are similar with those based on the temperature-dependent model.However,for the heating process of only one single physical state existing,the computed results based on the constant absorptivity model are a little different with those based on the temperature-dependent model.
There are three absorptivity models,i.e.the single constant absorptivity model,assembled constant absorptivity model whose liquid-state and solid-state absorptivity are both constant and temperature-dependent absorptivity models.In order to compare the influences of the three models on the numerical results,a spatial axis-symmetric finite element calculation model was established based on the three absorptivity models respectively.The laser heating process of an aluminum plate was simulated and the three numerical results were compared.The advantages and disadvantages and the application scope of the three absorptivity models were discussed.The results show that for the heating process of both solid state and liquid state existing evidently,the computed results based on the assembled constant absorptivity model are similar with those based on the temperature-dependent model.However,for the heating process of only one single physical state existing,the computed results based on the constant absorptivity model are a little different with those based on the temperature-dependent model.
2009, 33(6): 626-629.
doi: 10.3969/j.issn.1001-3806.2009.06.019
Abstract:
To overcome the limitation of fringe counting and phase analysis,a new method based on the time-frequency analysis is proposed to process the self-mixing interference signal.The frequency of the self-mixing interference signal is acquired by time-frequency analysis,and this frequency is equal to the Doppler shift,so the velocity of external object is gained easily.The simulation experiments show that the proposed method is very easy,effective,and accurate.
To overcome the limitation of fringe counting and phase analysis,a new method based on the time-frequency analysis is proposed to process the self-mixing interference signal.The frequency of the self-mixing interference signal is acquired by time-frequency analysis,and this frequency is equal to the Doppler shift,so the velocity of external object is gained easily.The simulation experiments show that the proposed method is very easy,effective,and accurate.
2009, 33(6): 630-632.
doi: 10.3969/j.issn.1001-3806.2009.06.020
Abstract:
In order to improve the recognition precision and anti-noise capability,based on correlation process,the moving property of correlation peak was judged according to the image flow,and the noise and target were distinguished with pipeline filter method,then the real target was obtained.Analytical and experimental results show that the recognition precision and anti-noise capability are increased by the improved pipeline filter for making good use of the characteristics of moving continuity and track consistency in an image sequence.The result is helpful to the tracking and identification of moving targets.
In order to improve the recognition precision and anti-noise capability,based on correlation process,the moving property of correlation peak was judged according to the image flow,and the noise and target were distinguished with pipeline filter method,then the real target was obtained.Analytical and experimental results show that the recognition precision and anti-noise capability are increased by the improved pipeline filter for making good use of the characteristics of moving continuity and track consistency in an image sequence.The result is helpful to the tracking and identification of moving targets.
2009, 33(6): 638-641.
doi: 10.3969/j.issn.1001-3806.2009.06.022
Abstract:
In order to study the effect of high-order dispersion on propagation of optical soliton and soliton couple,based on the split-step Fourier transform method,the optical soliton nonlinear SchrÖdinger equations with and without high-order dispersion effect were numerically calculated.It is found that the soliton pulse shape is correlative with the dispersion order.The oddnumber -order dispersion effect can cause the soliton and the soliton couple to oscillate at a single side with a loss of energy,and the sub pulse can be produced at the oscillating side.While the even-number-order dispersion effect can make the pulse width extended.The effect of the high-order dispersion would be weakened with the increase of the order number.
In order to study the effect of high-order dispersion on propagation of optical soliton and soliton couple,based on the split-step Fourier transform method,the optical soliton nonlinear SchrÖdinger equations with and without high-order dispersion effect were numerically calculated.It is found that the soliton pulse shape is correlative with the dispersion order.The oddnumber -order dispersion effect can cause the soliton and the soliton couple to oscillate at a single side with a loss of energy,and the sub pulse can be produced at the oscillating side.While the even-number-order dispersion effect can make the pulse width extended.The effect of the high-order dispersion would be weakened with the increase of the order number.
2009, 33(6): 642-644,647.
doi: 10.3969/j.issn.1001-3806.2009.06.023
Abstract:
In order to study the triangulation for the point cloud data collected by a three-dimension laser radar,in accordance with the line-by-line characteristics of laser radar scanning,an improved Delaunay triangulation method was proposed to mesh the point cloud data as an irregular triangulation network.Based on the geometric topology location information among radar point cloud data,focusing on the position relationship between adjacent scanning line of the point data,a preliminary match network was obtained according to their geometric relationship.A reasonable triangulation network for the object surface was acquired by means of local optimization on initial mesh by Delaunay rule.Meanwhile,a new judging rule was proposed to contrast the triangulation before and after the optimization on the network.The result shows that triangulation for point cloud with full use of its own characteristics can improve the speed of the algorithm obviously,and the rule for judging the triangulation can be used to evaluate the quality of network.
In order to study the triangulation for the point cloud data collected by a three-dimension laser radar,in accordance with the line-by-line characteristics of laser radar scanning,an improved Delaunay triangulation method was proposed to mesh the point cloud data as an irregular triangulation network.Based on the geometric topology location information among radar point cloud data,focusing on the position relationship between adjacent scanning line of the point data,a preliminary match network was obtained according to their geometric relationship.A reasonable triangulation network for the object surface was acquired by means of local optimization on initial mesh by Delaunay rule.Meanwhile,a new judging rule was proposed to contrast the triangulation before and after the optimization on the network.The result shows that triangulation for point cloud with full use of its own characteristics can improve the speed of the algorithm obviously,and the rule for judging the triangulation can be used to evaluate the quality of network.
2009, 33(6): 645-647.
doi: 10.3969/j.issn.1001-3806.2009.06.024
Abstract:
In order to study the anti-reflection property of two-dimension sub-wavelength gratings,the structure of twodimension grating of two-dimension photonic crystal was analyzed in detail.The two-dimension hexagonal structure photonic crystal was fabricated with three coherent beams incident onto the recording medium (photoresist) with holographic recording method.Taking the recording medium with relief structures as the master and using embossing technology,the structures can be replicated to polyvinylchlorid fihn.The measured result shows that the transmittance of the thin film at infrared wave band is enhanced,in good agreement with the theoretical result.
In order to study the anti-reflection property of two-dimension sub-wavelength gratings,the structure of twodimension grating of two-dimension photonic crystal was analyzed in detail.The two-dimension hexagonal structure photonic crystal was fabricated with three coherent beams incident onto the recording medium (photoresist) with holographic recording method.Taking the recording medium with relief structures as the master and using embossing technology,the structures can be replicated to polyvinylchlorid fihn.The measured result shows that the transmittance of the thin film at infrared wave band is enhanced,in good agreement with the theoretical result.
2009, 33(6): 648-650,653.
doi: 10.3969/j.issn.1001-3806.2009.06.025
Abstract:
In order to get better luminescence performance,binuclear rare earth complex of Eu3+ -doped with Tb3+ with benzoylacetone(BA) (as the first ligand) and 1,10-phenanathroline(1,10-phen) (as the second ligand) were synthesized.The properties of the complex Eu1-xTbx (BA)3 phen in different concentration were characterized by UV absorption spectra and fluorescent spectra,and also the energy transfer mechanism in the complexes was discussed.The result demonstrated that BA and 1,10-phen were appropriate ligands for the Eu3+,and Tb3+ had a strong sensitization effect on the fluorescence properties of Eu3+.The synthesized complex has excellent luminescent properties.
In order to get better luminescence performance,binuclear rare earth complex of Eu3+ -doped with Tb3+ with benzoylacetone(BA) (as the first ligand) and 1,10-phenanathroline(1,10-phen) (as the second ligand) were synthesized.The properties of the complex Eu1-xTbx (BA)3 phen in different concentration were characterized by UV absorption spectra and fluorescent spectra,and also the energy transfer mechanism in the complexes was discussed.The result demonstrated that BA and 1,10-phen were appropriate ligands for the Eu3+,and Tb3+ had a strong sensitization effect on the fluorescence properties of Eu3+.The synthesized complex has excellent luminescent properties.
2009, 33(6): 651-653.
doi: 10.3969/j.issn.1001-3806.2009.06.026
Abstract:
In order to investigate the effect of self-pulsing of Yb3+ -doped fiber laser,the variation of photon density and inversed populations with pump power,the relationship among the damping coefficient,the output coupling reflectivity and doped particle concentration,and the variation of inherent oscillation frequency with output coupling reflectivity were simulated.The results show that the self-pulsing effect can be compressed with the decrease of the feedback of the output end and the increase of the doping concentration.Some measures to compress the self pulse of a fiber laser were put forward,providing a theoretical base for the design of Yb3+ -doped fiber lasers.
In order to investigate the effect of self-pulsing of Yb3+ -doped fiber laser,the variation of photon density and inversed populations with pump power,the relationship among the damping coefficient,the output coupling reflectivity and doped particle concentration,and the variation of inherent oscillation frequency with output coupling reflectivity were simulated.The results show that the self-pulsing effect can be compressed with the decrease of the feedback of the output end and the increase of the doping concentration.Some measures to compress the self pulse of a fiber laser were put forward,providing a theoretical base for the design of Yb3+ -doped fiber lasers.
2009, 33(6): 654-656.
doi: 10.3969/j.issn.1001-3806.2009.06.027
Abstract:
In order to study the depolarization of compound binary wave plates,Mueller matrixes of different combined waveplates were studied by means of theoretical analysis and experimental verification.An ideal depolarizer can be combined with a λ/2 wave-plate and a λ/4 wave-plate rotating at different angular velocities with a certain ratio.Ideal depolarization can't be obtained from the combination of two λ/4 wave-plates or two λ/2 wave-plates.Experimental results are in agreement with those in theory.This study is a good guidance for the fabrication of compound binary wave plates and their application in laser engineering.
In order to study the depolarization of compound binary wave plates,Mueller matrixes of different combined waveplates were studied by means of theoretical analysis and experimental verification.An ideal depolarizer can be combined with a λ/2 wave-plate and a λ/4 wave-plate rotating at different angular velocities with a certain ratio.Ideal depolarization can't be obtained from the combination of two λ/4 wave-plates or two λ/2 wave-plates.Experimental results are in agreement with those in theory.This study is a good guidance for the fabrication of compound binary wave plates and their application in laser engineering.
2009, 33(6): 657-660,663.
doi: 10.3969/j.issn.1001-3806.2009.06.028
Abstract:
In order to improve the output beam quality and energy for high power lasers,firstly,the influence of intracavity aberrated perturbation on the eigenmode of unstable resonators was analyzed.Then,the effect of intracavity phase-tilted perturbation on the mode intensity and phase distribution for passive positive-branch confocal unstable resonators was calculated by means of numeric iterative method.Finally,the phase property of the output beam was analyzed based on Zernike mode-reconstruction theory so that the front 35-order Zernike aberration coefficients,the point spread function (PSF) and the integrated relative far-field intensity were obtained.Now the laser beam quality was fully illustrated.The results illustrate that in a confocal unstable resonator with a small Fresnel number,small phase-tilted perturbation has not only a remarkable influence on the output beam intensity but also the phase structure,and it makes higher order Zernike aberration such as A3,A7 and A10 increase in the beam phase structure.The results are of some reference to further investigation on the intracavity aberration compensation for high power lasers.
In order to improve the output beam quality and energy for high power lasers,firstly,the influence of intracavity aberrated perturbation on the eigenmode of unstable resonators was analyzed.Then,the effect of intracavity phase-tilted perturbation on the mode intensity and phase distribution for passive positive-branch confocal unstable resonators was calculated by means of numeric iterative method.Finally,the phase property of the output beam was analyzed based on Zernike mode-reconstruction theory so that the front 35-order Zernike aberration coefficients,the point spread function (PSF) and the integrated relative far-field intensity were obtained.Now the laser beam quality was fully illustrated.The results illustrate that in a confocal unstable resonator with a small Fresnel number,small phase-tilted perturbation has not only a remarkable influence on the output beam intensity but also the phase structure,and it makes higher order Zernike aberration such as A3,A7 and A10 increase in the beam phase structure.The results are of some reference to further investigation on the intracavity aberration compensation for high power lasers.
2009, 33(6): 661-663.
doi: 10.3969/j.issn.1001-3806.2009.06.029
Abstract:
In order to save the rare iceland and increase the shear difference,a new type of parallel beam splitter,combined iceland with glass,was designed.In the prism,there is a piece of optical glass between two parts of iceland with air gap or glue among them.At the premise of good extinction ratio and high transmittance,and the saving of the iceland,it can be indicated by the theory and experiment that the shear difference of the prism increases 3 times than that of the general parallel beam splitter.
In order to save the rare iceland and increase the shear difference,a new type of parallel beam splitter,combined iceland with glass,was designed.In the prism,there is a piece of optical glass between two parts of iceland with air gap or glue among them.At the premise of good extinction ratio and high transmittance,and the saving of the iceland,it can be indicated by the theory and experiment that the shear difference of the prism increases 3 times than that of the general parallel beam splitter.
2009, 33(6): 664-666,669.
doi: 10.3969/j.issn.1001-3806.2009.06.030
Abstract:
In order to improve the speed and accuracy of inversion of the wind obtained with a Doppler wind lidar,optimized Newton-Gaussian method of least squares was used to solve the wind inversion model.Its step-size and initial value of Newton-Gaussian were discussed and adjusted so that the method became more robust,and some inherent defects of traditional methods of velocity azimuth display(VAD) inversion were overcome.The inversion of low and mid partial wind-field was achieved with the algorithm adopted in an all-fiber Doppler weather radar.The algorithm not only improves the speed and accuracy of inversion of the wind,but also makes the result of inversion more stable and suitable for real-time calculation.
In order to improve the speed and accuracy of inversion of the wind obtained with a Doppler wind lidar,optimized Newton-Gaussian method of least squares was used to solve the wind inversion model.Its step-size and initial value of Newton-Gaussian were discussed and adjusted so that the method became more robust,and some inherent defects of traditional methods of velocity azimuth display(VAD) inversion were overcome.The inversion of low and mid partial wind-field was achieved with the algorithm adopted in an all-fiber Doppler weather radar.The algorithm not only improves the speed and accuracy of inversion of the wind,but also makes the result of inversion more stable and suitable for real-time calculation.
2009, 33(6): 667-669.
doi: 10.3969/j.issn.1001-3806.2009.06.031
Abstract:
Sequential posterior odd test approach can be used to reduce the size of the test samples and test cost,shorten the test period owing to its adoption of the test data information before test.Taking laser warning test for example,comparing with the traditional test data processing method,the sequential posterior odd test approach needs smaller samples,not only the test target value but also the probability of two kind errors have great influence on test sample size.
Sequential posterior odd test approach can be used to reduce the size of the test samples and test cost,shorten the test period owing to its adoption of the test data information before test.Taking laser warning test for example,comparing with the traditional test data processing method,the sequential posterior odd test approach needs smaller samples,not only the test target value but also the probability of two kind errors have great influence on test sample size.
2009, 33(6): 670-672.
doi: 10.3969/j.issn.1001-3806.2009.06.032
Abstract:
In order to have more comprehensive application in industry and military fields,a compact and long-life radio frequency(RF) excited waveguide CO2 laser was developed by means of Al-alloy laser housing,plat inductor coils instead of traditional rolling inductor,all-metal-sealed techniques and etc.The specifications of this laser are continuous or pulse output up to 20kHz modulating frequency,average laser output power up to 30W,over 1500h of working time and 1.5a of storage time.The results show that this laser has the characteristics of compact structure,steady output power,long life,continuous and pulse working-mode.It can be used both in industry and military fields.
In order to have more comprehensive application in industry and military fields,a compact and long-life radio frequency(RF) excited waveguide CO2 laser was developed by means of Al-alloy laser housing,plat inductor coils instead of traditional rolling inductor,all-metal-sealed techniques and etc.The specifications of this laser are continuous or pulse output up to 20kHz modulating frequency,average laser output power up to 30W,over 1500h of working time and 1.5a of storage time.The results show that this laser has the characteristics of compact structure,steady output power,long life,continuous and pulse working-mode.It can be used both in industry and military fields.
2009, 33(6): 633-637.
doi: 10.3969/j.issn.1001-3806.2009.06.021
Abstract:
In order to study the thermal effect of laser crystal end-pumped by diode lasers,the temperature rise and thermal distortion on pumped-face of the laser crystal were analytically studied.After analyzing the working characteristics of the laser crystal,taking into account of the aeolotropism of heat conduction of Nd:GdVO4 crystal,the general analytical expressions of the temperature field and thermal distortion field of Nd:GdVO4 crystal end-pumped by super-Gaussian beam were obtained based on the Poisson equation for aeolotropic heat conduction.The effect of different orders and spot size of super-Gaussian beam on the temperature field and the thermal distortion field of Nd:GdVO4 crystal was quantitatively analyzed.The results show that the maximal temperature rise and thermal distortion on the pumped-face of Nd:GdVO4 crystal doped with 0.012 (atomicity fraction) neodymium ion are 419.3℃ and 0.711 m respectively with the fifth-order super-Gaussian beam central-end-pumping,if the output power of diode laser is 30W,the transmission efficiency of the optical focusing coupler is 85%.The results have the theoretical instruction for estimating the thermal focus lens of Nd:GdVO4 crystal and designing the heat insensitive resonant cavity of lasers.
In order to study the thermal effect of laser crystal end-pumped by diode lasers,the temperature rise and thermal distortion on pumped-face of the laser crystal were analytically studied.After analyzing the working characteristics of the laser crystal,taking into account of the aeolotropism of heat conduction of Nd:GdVO4 crystal,the general analytical expressions of the temperature field and thermal distortion field of Nd:GdVO4 crystal end-pumped by super-Gaussian beam were obtained based on the Poisson equation for aeolotropic heat conduction.The effect of different orders and spot size of super-Gaussian beam on the temperature field and the thermal distortion field of Nd:GdVO4 crystal was quantitatively analyzed.The results show that the maximal temperature rise and thermal distortion on the pumped-face of Nd:GdVO4 crystal doped with 0.012 (atomicity fraction) neodymium ion are 419.3℃ and 0.711 m respectively with the fifth-order super-Gaussian beam central-end-pumping,if the output power of diode laser is 30W,the transmission efficiency of the optical focusing coupler is 85%.The results have the theoretical instruction for estimating the thermal focus lens of Nd:GdVO4 crystal and designing the heat insensitive resonant cavity of lasers.
