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RSS2012 Vol. 36, No. 2
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2012, 36(2): 145-150,178.
doi: 10.3969/j.issn.1001-3806.2012.02.001
[Abstract]
[PDF 396KB]
Abstract:
Recent achievements in laser welding of transformation induced plasticity(TRIP)-assisted steel were systematically summarized.In the laser welding process of TRIP-assisted steel,the formation of porosities in the weld bead,solidifying procedure of fusion zone(FZ),microstructure and properties of FZ and heat affected zone(HAZ)were emphatically described.Laser welding tailored blanks of TRIP-assisted steel with dissimilar materials,and laser cutting,laser brazing,laser spot welding of TRIP-assisted steel were also introduced.Future directions in research of laser welding of TRIP-assisted steels were pointed out.
Recent achievements in laser welding of transformation induced plasticity(TRIP)-assisted steel were systematically summarized.In the laser welding process of TRIP-assisted steel,the formation of porosities in the weld bead,solidifying procedure of fusion zone(FZ),microstructure and properties of FZ and heat affected zone(HAZ)were emphatically described.Laser welding tailored blanks of TRIP-assisted steel with dissimilar materials,and laser cutting,laser brazing,laser spot welding of TRIP-assisted steel were also introduced.Future directions in research of laser welding of TRIP-assisted steels were pointed out.
2012, 36(2): 160-164,169.
doi: 10.3969/j.issn.1001-3806.2012.02.004
Abstract:
Laser-feedback phenomena have been extensively investigated and concerned,and Doppler velocimetry is one of the important branches of laser-feedback research fields.The basic principle of laser-feedback Doppler velocimetry was introduced.Then the structures,principle,advantages and disadvantages of three types of laser Doppler velocimetry based on feedback effect were reviewed and discussed in detail.Finally,the development of velocity measurement based on laser feedback effect was also discussed.
Laser-feedback phenomena have been extensively investigated and concerned,and Doppler velocimetry is one of the important branches of laser-feedback research fields.The basic principle of laser-feedback Doppler velocimetry was introduced.Then the structures,principle,advantages and disadvantages of three types of laser Doppler velocimetry based on feedback effect were reviewed and discussed in detail.Finally,the development of velocity measurement based on laser feedback effect was also discussed.
2012, 36(2): 165-169.
doi: 10.3969/j.issn.1001-3806.2012.02.005
Abstract:
In order to obtain the behavior of evolution and self-deflection of two-photon separate screening-photovoltaic soliton pairs,the dynamical evolution,stability and self-deflecton of both solitons in separate dark-dark and bright-dark soliton pairs in a biased serial two-photon photorefractive crystal circuit were simulated.Under the limit conditions the optical wave has a spatial extent much less than the width of the crystal,only the dark soliton can affect the dynamical evolution and stability of the other soliton with the help of light-induced current,but the bright soliton cannot.For a bright-dark soliton pair,the deflection angle of the bright soliton decreases with the increase of the input intensity of the dark soliton.
In order to obtain the behavior of evolution and self-deflection of two-photon separate screening-photovoltaic soliton pairs,the dynamical evolution,stability and self-deflecton of both solitons in separate dark-dark and bright-dark soliton pairs in a biased serial two-photon photorefractive crystal circuit were simulated.Under the limit conditions the optical wave has a spatial extent much less than the width of the crystal,only the dark soliton can affect the dynamical evolution and stability of the other soliton with the help of light-induced current,but the bright soliton cannot.For a bright-dark soliton pair,the deflection angle of the bright soliton decreases with the increase of the input intensity of the dark soliton.
2012, 36(2): 174-178.
doi: 10.3969/j.issn.1001-3806.2012.02.007
Abstract:
With decades of development,a dynamic ring laser goniometer(DLG) becomes a kind of dynamic angle measuring system with high precision and sensitivity.The structure and principle of DLG system were introduced.In order to increase the accuracy of angle measurement and make the best use of the ring laser gyro,the major errors were analyzed qualitatively and calculated quantificationally,and the total angle measure uncertainty of the system was about 0.3''.The result shows that the quantization error will influence the accuracy of angle measurement significantly,and it's instructive to find the methods to increase the angle measuring accuracy further.
With decades of development,a dynamic ring laser goniometer(DLG) becomes a kind of dynamic angle measuring system with high precision and sensitivity.The structure and principle of DLG system were introduced.In order to increase the accuracy of angle measurement and make the best use of the ring laser gyro,the major errors were analyzed qualitatively and calculated quantificationally,and the total angle measure uncertainty of the system was about 0.3''.The result shows that the quantization error will influence the accuracy of angle measurement significantly,and it's instructive to find the methods to increase the angle measuring accuracy further.
2012, 36(2): 179-182,187.
doi: 10.3969/j.issn.1001-3806.2012.02.008
Abstract:
In order to decrease nonlinear distortion error in the state of wide-angle scanning of a two-dimension galvanometer scanning system,aiming at the defects of various errors in the system itself which cannot be overcame absolutely by single theoretical correction model,the correction model based on mapping connection between coordinates and angles was put forward.The error compensation surface of coordinate points was established by means of the least square surface fitting method,and the correction precision was effectively improved,the error of test points could be limited around 15μm.The scanning speed can be obviously increased by the grid correction table plugged by piecewise linear interpolation in the scanning plane,and the scanning speed can get to 25m/s or so.Simulation results show that the model is effective for real-time dynamic adjusting of nonlinear scanning.
In order to decrease nonlinear distortion error in the state of wide-angle scanning of a two-dimension galvanometer scanning system,aiming at the defects of various errors in the system itself which cannot be overcame absolutely by single theoretical correction model,the correction model based on mapping connection between coordinates and angles was put forward.The error compensation surface of coordinate points was established by means of the least square surface fitting method,and the correction precision was effectively improved,the error of test points could be limited around 15μm.The scanning speed can be obviously increased by the grid correction table plugged by piecewise linear interpolation in the scanning plane,and the scanning speed can get to 25m/s or so.Simulation results show that the model is effective for real-time dynamic adjusting of nonlinear scanning.
2012, 36(2): 183-187.
doi: 10.3969/j.issn.1001-3806.2012.02.009
Abstract:
In order to study the influence of parameters in 10nm-class aluminium-cladding optical waveguide,the attenuation total reflection spectrum was simulated theoretically with different thickness and refractive index of the cover and film,and the effect of characteristic parameters on the coupling was analyzed.Finally the experiments verified the influence of the thickness and refractive index of the metal layer on the coupling.At the same time,it was found that the refractive index of the nanometer-class aluminium film changed a lot.It is concluded that the number of the guided modes are affected by the thickness of the film,which is unrelated with the coupling depth;the refractive index of the film affects the number of the guided modes and the coupling depth;the number of the guided modes was unrelated with the thickness of the cover,which affects the coupling depth;for the same thickness of the cover,the coupling condition varies with the refractive index of the cover.The research opens the doors for the manufacture and the design of the pulse stretchers based on symmetrical metal-cladding optical waveguide.
In order to study the influence of parameters in 10nm-class aluminium-cladding optical waveguide,the attenuation total reflection spectrum was simulated theoretically with different thickness and refractive index of the cover and film,and the effect of characteristic parameters on the coupling was analyzed.Finally the experiments verified the influence of the thickness and refractive index of the metal layer on the coupling.At the same time,it was found that the refractive index of the nanometer-class aluminium film changed a lot.It is concluded that the number of the guided modes are affected by the thickness of the film,which is unrelated with the coupling depth;the refractive index of the film affects the number of the guided modes and the coupling depth;the number of the guided modes was unrelated with the thickness of the cover,which affects the coupling depth;for the same thickness of the cover,the coupling condition varies with the refractive index of the cover.The research opens the doors for the manufacture and the design of the pulse stretchers based on symmetrical metal-cladding optical waveguide.
2012, 36(2): 188-190.
doi: 10.3969/j.issn.1001-3806.2012.02.010
Abstract:
A laser conditioning system for large-aperture optical film is to determine the defect distribution of the large-diameter optical film and repair the defects with laser.In order to guarantee the speed and accuracy of detection system,the motion control and compensation of the defect detection part was improved.Theoretical analysis and experimental verification were conducted,and the reading accuracy of gratings,the servo control accuracy and the compensation value of image acquisition offset were obtained at different velocities.The results show that the detection accuracy of the laser conditioning system for large-diameter optical thin-film can be improved by means of multiple motion corrections and an appropriate motion compensation if controlling the motion of the servo motor and the map points based on point comparison function at high speed(20mm/s),thereby improving its laser pretreatment effect.
A laser conditioning system for large-aperture optical film is to determine the defect distribution of the large-diameter optical film and repair the defects with laser.In order to guarantee the speed and accuracy of detection system,the motion control and compensation of the defect detection part was improved.Theoretical analysis and experimental verification were conducted,and the reading accuracy of gratings,the servo control accuracy and the compensation value of image acquisition offset were obtained at different velocities.The results show that the detection accuracy of the laser conditioning system for large-diameter optical thin-film can be improved by means of multiple motion corrections and an appropriate motion compensation if controlling the motion of the servo motor and the map points based on point comparison function at high speed(20mm/s),thereby improving its laser pretreatment effect.
2012, 36(2): 191-193,197.
doi: 10.3969/j.issn.1001-3806.2012.02.011
Abstract:
In order to study the stimulated Brillouin scattering(SBS)effect on the pulse form of pulsed fiber laser amplifiers,a single frequency fiber laser amplifier system was built and its pulse waveform distortion was observed in the experiment.If continuing to improve pump power,a high power spike appeared at the distorted location,which was induced by the second-order SBS effect in a fiber.To verify this conclusion,the coupled equations contains the second-order Stokes wave were built and simulated and the results showed that the high peak power spike was the second-order Stokes wave of SBS effect.
In order to study the stimulated Brillouin scattering(SBS)effect on the pulse form of pulsed fiber laser amplifiers,a single frequency fiber laser amplifier system was built and its pulse waveform distortion was observed in the experiment.If continuing to improve pump power,a high power spike appeared at the distorted location,which was induced by the second-order SBS effect in a fiber.To verify this conclusion,the coupled equations contains the second-order Stokes wave were built and simulated and the results showed that the high peak power spike was the second-order Stokes wave of SBS effect.
2012, 36(2): 194-197.
doi: 10.3969/j.issn.1001-3806.2012.02.012
Abstract:
In order to remove the noise of infrared images,an image denoising method based on total variation was proposed,which inherits the advantage of edge preserving of the total variation(TV)model.A novel diffusion function was derived from the theory of smooth diffusion.Simultaneously,an edge detector operator was introduced to improve the related parameters of regularization term and fidelity term,which makes the denoised image avoid the staircase effect to a great extent.Finally,the implement of the algorithm was derived and the experimental results demonstrated the superior performance of the modified denoising algorithm.
In order to remove the noise of infrared images,an image denoising method based on total variation was proposed,which inherits the advantage of edge preserving of the total variation(TV)model.A novel diffusion function was derived from the theory of smooth diffusion.Simultaneously,an edge detector operator was introduced to improve the related parameters of regularization term and fidelity term,which makes the denoised image avoid the staircase effect to a great extent.Finally,the implement of the algorithm was derived and the experimental results demonstrated the superior performance of the modified denoising algorithm.
2012, 36(2): 198-199,207.
doi: 10.3969/j.issn.1001-3806.2012.02.013
Abstract:
In order to design a NO2 detection system to monitor air pollutants effectively,and improve the air quality,the laser spectrum analysis technique was applied,in which the blue laser light source at centre wavelength of 443.2nm was selected according to the absorption spectrum and the strong absorption peaks of NO2 in the visible range,and an experimental platform for NO2 was built.The transmission spectrum of NO2 with different volume fractions were tested and analyzed,and the linear relationship between absorbance and the volume fractions of NO2 was obtained by means of the least-square linear fit.The results show that the experimental system can detect the NO2 with sensitivity on the order of approximately 10-4,and it has the good application value.
In order to design a NO2 detection system to monitor air pollutants effectively,and improve the air quality,the laser spectrum analysis technique was applied,in which the blue laser light source at centre wavelength of 443.2nm was selected according to the absorption spectrum and the strong absorption peaks of NO2 in the visible range,and an experimental platform for NO2 was built.The transmission spectrum of NO2 with different volume fractions were tested and analyzed,and the linear relationship between absorbance and the volume fractions of NO2 was obtained by means of the least-square linear fit.The results show that the experimental system can detect the NO2 with sensitivity on the order of approximately 10-4,and it has the good application value.
2012, 36(2): 200-203.
doi: 10.3969/j.issn.1001-3806.2012.02.014
Abstract:
To decrease the thermal effect of a vertical-external-cavity surface-emitting laser and increase its output power,a high thermal conductivity SiC heatspreader was bond on the reverse-order semiconductor wafer with the capillary method,and then the substrate was removed by means of chemical etch.The characteristics of the laser formed by the substrate-etched wafer were experimentally studied.When the active region in the gain structure is InGaAs/AlGaAs multiple quantum wells,the pump source is a fiber-coupled 808nm diode laser,and the transmission of the output coupler is 3% at laser wavelength,the TEM00 mode output power of 0.52W and the optical-to-optical conversion efficiency of 20% are obtained at room temperature.The laser wavelength is 1018nm,and the spectrum width is 2nm(full width half maximum).The measured M2 factor in x and y direction of 1.01 and 1.00 demonstrate the near diffraction-limited Gaussian beam of the laser.It can be concluded that the substrate-etching technology can significantly improve the thermal property of vertical-external-cavity surface-emitting lasers and results in high power and high beam quality.
To decrease the thermal effect of a vertical-external-cavity surface-emitting laser and increase its output power,a high thermal conductivity SiC heatspreader was bond on the reverse-order semiconductor wafer with the capillary method,and then the substrate was removed by means of chemical etch.The characteristics of the laser formed by the substrate-etched wafer were experimentally studied.When the active region in the gain structure is InGaAs/AlGaAs multiple quantum wells,the pump source is a fiber-coupled 808nm diode laser,and the transmission of the output coupler is 3% at laser wavelength,the TEM00 mode output power of 0.52W and the optical-to-optical conversion efficiency of 20% are obtained at room temperature.The laser wavelength is 1018nm,and the spectrum width is 2nm(full width half maximum).The measured M2 factor in x and y direction of 1.01 and 1.00 demonstrate the near diffraction-limited Gaussian beam of the laser.It can be concluded that the substrate-etching technology can significantly improve the thermal property of vertical-external-cavity surface-emitting lasers and results in high power and high beam quality.
2012, 36(2): 204-207.
doi: 10.3969/j.issn.1001-3806.2012.02.015
Abstract:
In order to improve the temperature sensitivity of photonic bandgap fiber,a new structure was proposed merging high refractive index liquid cylinders into the surround of the fiber core.By means of full-vector finite element method,the influence of temperature on the effective refractive index,core energy,effective mode area was obtained.The numerical results show that when the temperature increases,the effective refractive index and the effective mode area decrease,the core energy increases,and the zero dispersion wavelength moves towards longer wavelength.These changes are quite significant when the wavelength is short.The proposed structure improves the temperature sensitivity of the transmission characteristics,which makes photonic bandgap photonic crystal fibers more suitable for temperature sensing applications.
In order to improve the temperature sensitivity of photonic bandgap fiber,a new structure was proposed merging high refractive index liquid cylinders into the surround of the fiber core.By means of full-vector finite element method,the influence of temperature on the effective refractive index,core energy,effective mode area was obtained.The numerical results show that when the temperature increases,the effective refractive index and the effective mode area decrease,the core energy increases,and the zero dispersion wavelength moves towards longer wavelength.These changes are quite significant when the wavelength is short.The proposed structure improves the temperature sensitivity of the transmission characteristics,which makes photonic bandgap photonic crystal fibers more suitable for temperature sensing applications.
2012, 36(2): 208-212,216.
doi: 10.3969/j.issn.1001-3806.2012.02.016
Abstract:
In order to study transmission property of 1-D ternary magnetized plasma photonic crystals,the transfer matrix method was applied to get the transmission characteristics for TE wave,divided into left-handed and right-handed circularly polarized waves after propagating through 1-D ternary magnetized plasma photonic crystals.The calculated transmission coefficients were used to analyze the effect of periodic constant,dielectric constant,thickness of dielectric layers and parameter of plasma on the transmission characteristics.The results illustrate that the numbers and width of band gaps can be tuned by changing dielectric constant,thickness of dielectric layer and plasma frequency,the width of band gaps can not be affected by increasing periodic and plasma collision frequency.The band gaps for right-handed circularly polarized wave can be tuned by the plasma gyro frequency,but band gaps for the left-handed circularly polarized wave can't.The results are good theoretical references to design 1-D ternary magnetized plasma photonic crystal devices.
In order to study transmission property of 1-D ternary magnetized plasma photonic crystals,the transfer matrix method was applied to get the transmission characteristics for TE wave,divided into left-handed and right-handed circularly polarized waves after propagating through 1-D ternary magnetized plasma photonic crystals.The calculated transmission coefficients were used to analyze the effect of periodic constant,dielectric constant,thickness of dielectric layers and parameter of plasma on the transmission characteristics.The results illustrate that the numbers and width of band gaps can be tuned by changing dielectric constant,thickness of dielectric layer and plasma frequency,the width of band gaps can not be affected by increasing periodic and plasma collision frequency.The band gaps for right-handed circularly polarized wave can be tuned by the plasma gyro frequency,but band gaps for the left-handed circularly polarized wave can't.The results are good theoretical references to design 1-D ternary magnetized plasma photonic crystal devices.
2012, 36(2): 213-213.
Abstract:
In order to discuss the possibility of manufacturing controllable nanostrucures by femtosecond laser, orientation-controllable nanogratings are firstly induced on bulk Ag target by femtosecond pulsed laser whose linear plolarization angle is adjusted continuously by two inserted half-wave plates. Then, based on energy accumulation effects and the dependence of the orientation of self-organized nanogratings on laser polarization angle obtained from our experiments, it is discussed how to controlably induce two-dimensional periodic nanostructrues on target surfaces by femtosecond laser. In addition, conbining the laser scannning approach with muli-beam alternative ablations method, large-area and high-uniformity nanostructures with tunable nanounits are expected to be manufactured. Our inverstigaitons are expected to open a new approach of inducing two-dimensional periodic nanostructures with tunable nanounits and to offer some important clues for controllably manufacturing periodic nanostructures on target surfaces by ultrashort pulsed laser.
In order to discuss the possibility of manufacturing controllable nanostrucures by femtosecond laser, orientation-controllable nanogratings are firstly induced on bulk Ag target by femtosecond pulsed laser whose linear plolarization angle is adjusted continuously by two inserted half-wave plates. Then, based on energy accumulation effects and the dependence of the orientation of self-organized nanogratings on laser polarization angle obtained from our experiments, it is discussed how to controlably induce two-dimensional periodic nanostructrues on target surfaces by femtosecond laser. In addition, conbining the laser scannning approach with muli-beam alternative ablations method, large-area and high-uniformity nanostructures with tunable nanounits are expected to be manufactured. Our inverstigaitons are expected to open a new approach of inducing two-dimensional periodic nanostructures with tunable nanounits and to offer some important clues for controllably manufacturing periodic nanostructures on target surfaces by ultrashort pulsed laser.
2012, 36(2): 255-257,261.
doi: 10.3969/j.issn.1001-3806.2012.02.028
Abstract:
In order to measure the wide-band phase retardation variation of quartz wave-plates,a new method was proposed based on the principle of continuous polarization interference,and the data processing method for the corresponding retardation variation of each wavelength was given.In the method,relative measurement was carried out with the Shimadzu UV-3101PC spectrophotometer to increase the stable reliability of the data collection,and the continuous polarization interference spectrum of the quartz wave-plate in known thickness at 300nm～800nm wave band was obtained.Then theoretical analysis and experimental verification were carried out.The results show that the experimental curve and theoretical curve fit well,and the measurement of the average error is less than 2°.It has important practical significance for study on the retardation dispersion properties of the wave-plates and the guidance of the technical process.
In order to measure the wide-band phase retardation variation of quartz wave-plates,a new method was proposed based on the principle of continuous polarization interference,and the data processing method for the corresponding retardation variation of each wavelength was given.In the method,relative measurement was carried out with the Shimadzu UV-3101PC spectrophotometer to increase the stable reliability of the data collection,and the continuous polarization interference spectrum of the quartz wave-plate in known thickness at 300nm～800nm wave band was obtained.Then theoretical analysis and experimental verification were carried out.The results show that the experimental curve and theoretical curve fit well,and the measurement of the average error is less than 2°.It has important practical significance for study on the retardation dispersion properties of the wave-plates and the guidance of the technical process.
2012, 36(2): 151-153,159.
doi: 10.3969/j.issn.1001-3806.2012.02.002
Abstract:
In order to lighten weight of a laser rangefinder and improve the efficiency of optical alignment,a rotary dual-wedge pair was designed to align the optical axes.The mathematical model of the optical axis parallel deviation and the dual-wedge rotary angle was established,and the corresponding formula was derived.With a dual-wedge pair applied in a photoelectric fire control system of a light-weight weapon,the correction accuracy reached 0.1mrad.Experimental results indicate that this method is suitable to miniature the volume and weight,eliminate the influence of environment such as the temperature,shock.It is convenient for alignment and maintenance.
In order to lighten weight of a laser rangefinder and improve the efficiency of optical alignment,a rotary dual-wedge pair was designed to align the optical axes.The mathematical model of the optical axis parallel deviation and the dual-wedge rotary angle was established,and the corresponding formula was derived.With a dual-wedge pair applied in a photoelectric fire control system of a light-weight weapon,the correction accuracy reached 0.1mrad.Experimental results indicate that this method is suitable to miniature the volume and weight,eliminate the influence of environment such as the temperature,shock.It is convenient for alignment and maintenance.
2012, 36(2): 154-159.
doi: 10.3969/j.issn.1001-3806.2012.02.003
Abstract:
Fiber laser welding is a promising technology which can be widely used in industry and it attracts attention of the researchers in the worldwide.In this article,a detailed review of the research status on the high power fiber laser welding of low carbon,low alloy steel,stainless steel,high strength steel,aluminum alloy,magnesium alloy,and titanium alloy,et al,were discussed.Also,the characteristics of fiber laser welding developed were presented.Finally,the research progress of high power fiber laser welding was summarized and further work on the fiber laser welding process was described.Fiber laser welding is a promising technology which can be widely used in industry and it attracts attention of the researchers in the worldwide.In this article,a detailed review of the research status on the high power fiber laser welding of low carbon,low alloy steel,stainless steel,high strength steel,aluminum alloy,magnesium alloy,and titanium alloy,et al,were discussed.Also,the characteristics of fiber laser welding developed were presented.Finally,the research progress of high power fiber laser welding was summarized and further work on the fiber laser welding process was described.
Fiber laser welding is a promising technology which can be widely used in industry and it attracts attention of the researchers in the worldwide.In this article,a detailed review of the research status on the high power fiber laser welding of low carbon,low alloy steel,stainless steel,high strength steel,aluminum alloy,magnesium alloy,and titanium alloy,et al,were discussed.Also,the characteristics of fiber laser welding developed were presented.Finally,the research progress of high power fiber laser welding was summarized and further work on the fiber laser welding process was described.Fiber laser welding is a promising technology which can be widely used in industry and it attracts attention of the researchers in the worldwide.In this article,a detailed review of the research status on the high power fiber laser welding of low carbon,low alloy steel,stainless steel,high strength steel,aluminum alloy,magnesium alloy,and titanium alloy,et al,were discussed.Also,the characteristics of fiber laser welding developed were presented.Finally,the research progress of high power fiber laser welding was summarized and further work on the fiber laser welding process was described.
2012, 36(2): 213-216.
doi: 10.3969/j.issn.1001-3806.2012.02.018
Abstract:
基于猫眼效应的激光主动侦察技术有效地结合了激光技术、成像传感技术和微弱目标的信息处理技术,可实现对远距离微弱目标的主动探测和识别,是光电对抗领域的一项重要技术,其中作用距离是侦察系统的主要参量之一。为了评估激光主动侦察系统的作用距离,以猫眼目标的光学窗口所反射的激光回波功率为基础,分析了影响作用距离的因素,建立了最大作用距离的数学物理模型,数值模拟了发射激光峰值功率、发射激光束散角、大气能见度、探测器灵敏度以及等效反射面离焦量对最大作用距离的影响。结果表明,通过减小发射激光束散角,提高探测器灵敏度可以有效提高系统的作用距离;为满足不同情况的天气需求,可选择不同波长的激光光源。这一结果可用于指导激光主动侦察的系统设计或者作为衡量系统性能的标准。
基于猫眼效应的激光主动侦察技术有效地结合了激光技术、成像传感技术和微弱目标的信息处理技术,可实现对远距离微弱目标的主动探测和识别,是光电对抗领域的一项重要技术,其中作用距离是侦察系统的主要参量之一。为了评估激光主动侦察系统的作用距离,以猫眼目标的光学窗口所反射的激光回波功率为基础,分析了影响作用距离的因素,建立了最大作用距离的数学物理模型,数值模拟了发射激光峰值功率、发射激光束散角、大气能见度、探测器灵敏度以及等效反射面离焦量对最大作用距离的影响。结果表明,通过减小发射激光束散角,提高探测器灵敏度可以有效提高系统的作用距离;为满足不同情况的天气需求,可选择不同波长的激光光源。这一结果可用于指导激光主动侦察的系统设计或者作为衡量系统性能的标准。
2012, 36(2): 228-229,250.
doi: 10.3969/j.issn.1001-3806.2012.02.022
Abstract:
为了分析研究激光致盲干扰的作战能力,评估激光致盲干扰的作战效能,基于激光致盲干扰的干扰原理和干扰效果评估准则,采用效能评估分析方法,总结出激光致盲干扰的干扰方程,从干扰方程出发,提出了致盲距离、致盲概率两个效能分析指标,给出了概念、计算模型,并进行了理论分析和仿真验证。结果表明,激光干扰机的输出功率越高,光束质量越好,致盲距离就越大;激光干扰机的定位精度越高,致盲概率就越大,从而分析总结出影响激光致盲干扰效果的因素,为激光致盲干扰研究奠定了基础。
为了分析研究激光致盲干扰的作战能力,评估激光致盲干扰的作战效能,基于激光致盲干扰的干扰原理和干扰效果评估准则,采用效能评估分析方法,总结出激光致盲干扰的干扰方程,从干扰方程出发,提出了致盲距离、致盲概率两个效能分析指标,给出了概念、计算模型,并进行了理论分析和仿真验证。结果表明,激光干扰机的输出功率越高,光束质量越好,致盲距离就越大;激光干扰机的定位精度越高,致盲概率就越大,从而分析总结出影响激光致盲干扰效果的因素,为激光致盲干扰研究奠定了基础。
2012, 36(2): 217-220,224.
doi: 10.3969/j.issn.1001-3806.2012.02.019
Abstract:
为了解决毫米波雷达回波噪声的污染,剔除Ka波段雷达探测数据中的散点噪声,得到雷达真实的探测大气云粒子回波,采用自适应滤波方法,改进并使其适用于Ka波段雷达资料的噪声剔除,同时进行了理论分析和实验论证。结果表明,相对于传统的中值滤波,自适应滤波具有明显的滤波性能,不仅可以剔除噪声,并有效地保留了雷达探测数据的局部细节。
为了解决毫米波雷达回波噪声的污染,剔除Ka波段雷达探测数据中的散点噪声,得到雷达真实的探测大气云粒子回波,采用自适应滤波方法,改进并使其适用于Ka波段雷达资料的噪声剔除,同时进行了理论分析和实验论证。结果表明,相对于传统的中值滤波,自适应滤波具有明显的滤波性能,不仅可以剔除噪声,并有效地保留了雷达探测数据的局部细节。
2012, 36(2): 221-224.
doi: 10.3969/j.issn.1001-3806.2012.02.020
Abstract:
外差信号处理系统是外差干涉测量系统精度测量的重要组成部分。为了实现外差干涉的相位移测量,采用一种整数计数和小数计数相结合的外差信号相位测量方法,利用VERILOG语言编写整数计数以及小数计数模块程序,并进行了仿真验证,理论分析测量分辨率为(11π/375)rad。结果表明,该方案硬件实现电路简单、可移植性强,只需一个基于现场可编程门阵列的最小系统即可实现。
外差信号处理系统是外差干涉测量系统精度测量的重要组成部分。为了实现外差干涉的相位移测量,采用一种整数计数和小数计数相结合的外差信号相位测量方法,利用VERILOG语言编写整数计数以及小数计数模块程序,并进行了仿真验证,理论分析测量分辨率为(11π/375)rad。结果表明,该方案硬件实现电路简单、可移植性强,只需一个基于现场可编程门阵列的最小系统即可实现。
2012, 36(2): 230-232,237.
doi: 10.3969/j.issn.1001-3806.2012.02.023
Abstract:
为了在材料表面激光3维改性系统中有效地消除系统误差并提高系统精度,根据材料表面改性图形为填充图样的原理,采用3维扫描线重建算法对空间封闭曲线进行了激光半径补偿。经过交点计算及闭合检查,对空间3维数据进行重建,基于VC++平台实现了半径补偿算法,完成重建图形显示并控制系统完成材料表面激光3维改性实验。经理论分析及实验验证,重建后的3维图形补偿了0.07mm光斑直径距离,取得了与标准值更加接近的实验数据。结果表明,此种算法具有一般性,可有效消除系统误差并提高系统精度。
为了在材料表面激光3维改性系统中有效地消除系统误差并提高系统精度,根据材料表面改性图形为填充图样的原理,采用3维扫描线重建算法对空间封闭曲线进行了激光半径补偿。经过交点计算及闭合检查,对空间3维数据进行重建,基于VC++平台实现了半径补偿算法,完成重建图形显示并控制系统完成材料表面激光3维改性实验。经理论分析及实验验证,重建后的3维图形补偿了0.07mm光斑直径距离,取得了与标准值更加接近的实验数据。结果表明,此种算法具有一般性,可有效消除系统误差并提高系统精度。
2012, 36(2): 238-242.
doi: 10.3969/j.issn.1001-3806.2012.02.025
Abstract:
为了得到激光光束的某些参量,为设计和改进激光器提供依据,建立了一套激光光斑自动采集与分析系统,搭建了实验平台,并编写了一套基于虚拟仪器开发平台LabVIEW及其图像处理软件包NI Vision的用于采集和分析激光光斑的软件。该软件能实时显示光斑中心位置的漂移轨迹、在x方向和y方向漂移的标准差及其随时间变化的趋势等,同时,还能对基模高斯光束进行分析。经过去噪处理的光斑图样能以3维灰度图的形式显示出来,得到任意剖面的光强信息,并以此进行高斯曲线拟合,得出拟合参量以判断光强曲线接近高斯曲线的程度。结果表明,这种系统可以动态地采集光斑信息并进行处理,具有实时性。
为了得到激光光束的某些参量,为设计和改进激光器提供依据,建立了一套激光光斑自动采集与分析系统,搭建了实验平台,并编写了一套基于虚拟仪器开发平台LabVIEW及其图像处理软件包NI Vision的用于采集和分析激光光斑的软件。该软件能实时显示光斑中心位置的漂移轨迹、在x方向和y方向漂移的标准差及其随时间变化的趋势等,同时,还能对基模高斯光束进行分析。经过去噪处理的光斑图样能以3维灰度图的形式显示出来,得到任意剖面的光强信息,并以此进行高斯曲线拟合,得出拟合参量以判断光强曲线接近高斯曲线的程度。结果表明,这种系统可以动态地采集光斑信息并进行处理,具有实时性。
2012, 36(2): 247-250.
doi: 10.3969/j.issn.1001-3806.2012.02.027
Abstract:
为了使全光纤位移干涉测速系统能够准确稳定地测速,采用小波基分析问题的方法,对全光纤位移干涉测速仪信号进行了理论分析,并选取6种小波基函数进行计算机模拟,选定了适合全光纤位移干涉测速仪信号分析方法的最优小波基。与此同时,分别利用自由落体运动实验和高速爆轰实验验证了系统的精确性和稳定性,精确度达到99%,稳定性极高。结果表明,最优小波基的选取是合理的。
为了使全光纤位移干涉测速系统能够准确稳定地测速,采用小波基分析问题的方法,对全光纤位移干涉测速仪信号进行了理论分析,并选取6种小波基函数进行计算机模拟,选定了适合全光纤位移干涉测速仪信号分析方法的最优小波基。与此同时,分别利用自由落体运动实验和高速爆轰实验验证了系统的精确性和稳定性,精确度达到99%,稳定性极高。结果表明,最优小波基的选取是合理的。
2012, 36(2): 258-261.
doi: 10.3969/j.issn.1001-3806.2012.02.030
Abstract:
为了改进钛合金的耐磨性能,开发在高温环境、大温度落差条件下使用的具有热应力缓和功能的新型涂层,应用Nd:YAG激光在钛合金表面制备了钛基梯度功能耐磨涂层,观察了微观组织,分析了生成相,测量了梯度功能耐磨涂层、非梯度功能耐磨涂层和Ti600基体在大气环境室温下的摩擦磨损性能。结果表明,原位合成的TiC球状增强相弥散均匀分布在梯度功能耐磨涂层中,主要呈3种不同的形态,即粗大的或不完整的树枝晶、相对较为细小的等轴晶或近似等轴晶和细小短纤维状;梯度功能耐磨涂层和非梯度功能耐磨涂层表现出较优异的耐磨性能,摩擦系数和磨损率显著降低,平均是Ti600基体的0.3倍~0.5倍。
为了改进钛合金的耐磨性能,开发在高温环境、大温度落差条件下使用的具有热应力缓和功能的新型涂层,应用Nd:YAG激光在钛合金表面制备了钛基梯度功能耐磨涂层,观察了微观组织,分析了生成相,测量了梯度功能耐磨涂层、非梯度功能耐磨涂层和Ti600基体在大气环境室温下的摩擦磨损性能。结果表明,原位合成的TiC球状增强相弥散均匀分布在梯度功能耐磨涂层中,主要呈3种不同的形态,即粗大的或不完整的树枝晶、相对较为细小的等轴晶或近似等轴晶和细小短纤维状;梯度功能耐磨涂层和非梯度功能耐磨涂层表现出较优异的耐磨性能,摩擦系数和磨损率显著降低,平均是Ti600基体的0.3倍~0.5倍。
2012, 36(2): 271-274.
doi: 10.3969/j.issn.1001-3806.2012.02.034
Abstract:
为了研究猫眼光学系统中分划板失调对入射光束的反射特性影响,考虑光学元件的等效光阑作用,将失调光阑孔径函数展开为有限项复高斯函数之和,利用失调光学系统的广义衍射公式,推导出入射光束经含分划板失调猫眼光学系统的反射光束场分布的近似解析式,得到反射光束场分布与入射光束光学参量、分划板孔径尺寸和分划板失调量之间的关系,对特定猫眼光学系统定量分析了分划板失调对反射光束场分布的影响。结果表明,分划板失调对反射光束场分布产生影响,特别是对远场光场分布影响显著。
为了研究猫眼光学系统中分划板失调对入射光束的反射特性影响,考虑光学元件的等效光阑作用,将失调光阑孔径函数展开为有限项复高斯函数之和,利用失调光学系统的广义衍射公式,推导出入射光束经含分划板失调猫眼光学系统的反射光束场分布的近似解析式,得到反射光束场分布与入射光束光学参量、分划板孔径尺寸和分划板失调量之间的关系,对特定猫眼光学系统定量分析了分划板失调对反射光束场分布的影响。结果表明,分划板失调对反射光束场分布产生影响,特别是对远场光场分布影响显著。
2012, 36(2): 225-227.
doi: 10.3969/j.issn.1001-3806.2012.02.021
Abstract:
为了研究2维三角晶格空气孔型光子晶体TE模和TM模偏振的禁带宽度与介质柱半径的变化关系,采用平面波展开法数值计算和分析了空气孔型光子晶体的带隙分布及波导耦合特性。结果表明,光子禁带的宽度会随着介质柱半径的大小而变化,束缚在光子晶体中的光波可以在波导和谐振腔中高效率地传输,达到选择输出光波的目的。这种特性在光学集成电路中具有重要而潜在的应用价值。
为了研究2维三角晶格空气孔型光子晶体TE模和TM模偏振的禁带宽度与介质柱半径的变化关系,采用平面波展开法数值计算和分析了空气孔型光子晶体的带隙分布及波导耦合特性。结果表明,光子禁带的宽度会随着介质柱半径的大小而变化,束缚在光子晶体中的光波可以在波导和谐振腔中高效率地传输,达到选择输出光波的目的。这种特性在光学集成电路中具有重要而潜在的应用价值。
2012, 36(2): 251-254,264.
doi: 10.3969/j.issn.1001-3806.2012.02.029
Abstract:
为了对飞秒激光加工微纳米尺度波导器件的可行性进行分析,采用有限差分光束传输法对余弦型Y波导合波器的耦合夹角大小对合路光场的影响进行了仿真模拟,分析了光场强度、分支角度以及损耗等之间的关系,得到当耦合夹角为0.6rad时,输入光场相互隔离,附加损耗低至0.45dB,传输效率接近90%的结果。结果表明,在石英玻璃这种高损伤阈值的材料中利用飞秒激光直写制备光合波器件时,预先对加工的微纳器件进行仿真模拟,在微纳光子集成及微纳米光波导中具有很重要的意义。
为了对飞秒激光加工微纳米尺度波导器件的可行性进行分析,采用有限差分光束传输法对余弦型Y波导合波器的耦合夹角大小对合路光场的影响进行了仿真模拟,分析了光场强度、分支角度以及损耗等之间的关系,得到当耦合夹角为0.6rad时,输入光场相互隔离,附加损耗低至0.45dB,传输效率接近90%的结果。结果表明,在石英玻璃这种高损伤阈值的材料中利用飞秒激光直写制备光合波器件时,预先对加工的微纳器件进行仿真模拟,在微纳光子集成及微纳米光波导中具有很重要的意义。
2012, 36(2): 268-270,288.
doi: 10.3969/j.issn.1001-3806.2012.02.033
Abstract:
为了提高弹光调制中非线性光程差干涉信号的光谱反演效率,采用非均匀快速傅里叶变换算法对弹光调制相位非均匀采样干涉信号反演光谱进行了仿真,得到1024点反演速率较直接计算提高20倍,平均误差达到0.87%的结果。结果表明,该算法可实现弹光调制干涉信号的快速、高精度反演,给硬件实现弹光调制反演光谱提供了一定的参考依据。
为了提高弹光调制中非线性光程差干涉信号的光谱反演效率,采用非均匀快速傅里叶变换算法对弹光调制相位非均匀采样干涉信号反演光谱进行了仿真,得到1024点反演速率较直接计算提高20倍,平均误差达到0.87%的结果。结果表明,该算法可实现弹光调制干涉信号的快速、高精度反演,给硬件实现弹光调制反演光谱提供了一定的参考依据。
2012, 36(2): 275-279,284.
doi: 10.3969/j.issn.1001-3806.2012.02.035
Abstract:
为了解决高能激光器输出光束的光束质量随时间蜕变的问题,提出了一种主动光学元件的结构,只使用一个驱动器使反射镜的曲率产生可控制的改变,用以补偿高能激光器中增益介质或光学元件因热效应而产生的球差。通过理论模拟计算和实验研究对比验证,这种结构能够使单晶硅基底的反射镜产生微小变形,通过精确控制驱动器,可以使反射镜产生所需要的曲率变化。结果表明,这种主动光学元件可以用于谐振腔内补偿高能激光器中热效应产生的球差项的影响。
为了解决高能激光器输出光束的光束质量随时间蜕变的问题,提出了一种主动光学元件的结构,只使用一个驱动器使反射镜的曲率产生可控制的改变,用以补偿高能激光器中增益介质或光学元件因热效应而产生的球差。通过理论模拟计算和实验研究对比验证,这种结构能够使单晶硅基底的反射镜产生微小变形,通过精确控制驱动器,可以使反射镜产生所需要的曲率变化。结果表明,这种主动光学元件可以用于谐振腔内补偿高能激光器中热效应产生的球差项的影响。
2012, 36(2): 233-237.
doi: 10.3969/j.issn.1001-3806.2012.02.024
Abstract:
为了探讨脐带血红细胞和先天性心脏病患儿红细胞的内容物的改变情况及其变化机理,为先天性心脏病的产前诊断提供有用信息,采用激光光镊喇曼光谱系统,测定了脐带血红细胞与先天性心脏病患儿红细胞的喇曼光谱,通过对两者喇曼光谱进行比较分析,发现脐带血红细胞与先天性心脏病患儿红细胞的光镊喇曼光谱有较大的差异。与脐带血红细胞相比,先天性心脏病患儿红细胞的整体谱线偏弱,部分的特征谱线发生位移。该研究结果将为提高胎儿先天性心脏病的检出率提供一种新的、快速简便的光谱分析手段,为临床诊断提供有力的实验依据。
为了探讨脐带血红细胞和先天性心脏病患儿红细胞的内容物的改变情况及其变化机理,为先天性心脏病的产前诊断提供有用信息,采用激光光镊喇曼光谱系统,测定了脐带血红细胞与先天性心脏病患儿红细胞的喇曼光谱,通过对两者喇曼光谱进行比较分析,发现脐带血红细胞与先天性心脏病患儿红细胞的光镊喇曼光谱有较大的差异。与脐带血红细胞相比,先天性心脏病患儿红细胞的整体谱线偏弱,部分的特征谱线发生位移。该研究结果将为提高胎儿先天性心脏病的检出率提供一种新的、快速简便的光谱分析手段,为临床诊断提供有力的实验依据。
2012, 36(2): 243-246.
doi: 10.3969/j.issn.1001-3806.2012.02.026
Abstract:
为了研究3阶色散对相位整形不归零(phase-shaped nonreturn-to-zero,PSNRZ)码传输性能的影响,通过仿真对带有初始啁啾的高斯脉冲受3阶色散影响的情况进行了研究。研究发现,初始啁啾的存在会严重加剧3阶色散对波形演化的影响。而通过对PSNRZ码传输性能的仿真进一步发现,与3阶色散补偿后相比,未补偿时的传输距离受到很大限制,当链路残余色散低于20ps/nm时,最大传输距离减小超过500km。结果表明,当采用PSNRZ码通信时,必须对3阶色散进行补偿。
为了研究3阶色散对相位整形不归零(phase-shaped nonreturn-to-zero,PSNRZ)码传输性能的影响,通过仿真对带有初始啁啾的高斯脉冲受3阶色散影响的情况进行了研究。研究发现,初始啁啾的存在会严重加剧3阶色散对波形演化的影响。而通过对PSNRZ码传输性能的仿真进一步发现,与3阶色散补偿后相比,未补偿时的传输距离受到很大限制,当链路残余色散低于20ps/nm时,最大传输距离减小超过500km。结果表明,当采用PSNRZ码通信时,必须对3阶色散进行补偿。
2012, 36(2): 262-264.
doi: 10.3969/j.issn.1001-3806.2012.02.031
Abstract:
为了降低环境振动对光学谐振腔稳定性的影响,设计了对振动不敏感的超稳腔,采用有限元数值模拟的方法,通过改变相关参量,对两U型片支撑和双横梁支撑两种圆柱体腔的支撑方式进行了数值模拟,得到了腔体的形变图。结果表明,通过改进腔的支撑方式和调整支撑位置,可以降低腔长对振动的敏感度,找到腔长变化最小且两腔镜平行的关键支撑位置。该结果可用于激光稳频和高精密激光光谱实验中。
为了降低环境振动对光学谐振腔稳定性的影响,设计了对振动不敏感的超稳腔,采用有限元数值模拟的方法,通过改变相关参量,对两U型片支撑和双横梁支撑两种圆柱体腔的支撑方式进行了数值模拟,得到了腔体的形变图。结果表明,通过改进腔的支撑方式和调整支撑位置,可以降低腔长对振动的敏感度,找到腔长变化最小且两腔镜平行的关键支撑位置。该结果可用于激光稳频和高精密激光光谱实验中。
2012, 36(2): 280-284.
doi: 10.3969/j.issn.1001-3806.2012.02.036
Abstract:
为了研究圆截面Nd:GdVO4激光晶体在端面抽运下的温度场和热变形场,考虑弹性体的协调性,采用有限元方法进行了分析,得到了端面抽运激光晶体棒内温度场和热形变场的数值解,并与相同条件下传热学方法计算结果进行了比较。结果表明,两种方法具有相同的最高温度,但有限元法计算所得最大变形量偏小。这一分析结果对端面抽运固体激光的优化设计提供了参考。
为了研究圆截面Nd:GdVO4激光晶体在端面抽运下的温度场和热变形场,考虑弹性体的协调性,采用有限元方法进行了分析,得到了端面抽运激光晶体棒内温度场和热形变场的数值解,并与相同条件下传热学方法计算结果进行了比较。结果表明,两种方法具有相同的最高温度,但有限元法计算所得最大变形量偏小。这一分析结果对端面抽运固体激光的优化设计提供了参考。
