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RSS1997 Vol. 21, No. 6
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1997, 21(6): 321-326.
[Abstract]
[PDF 357KB]
Abstract:
This paper briefly reviews the features of the tactical laser air defense weapons and the tests demontrated that Nautilus laser weapon could intercept short range missiles.We analyze the vulnerability of short range missiles for laser through estimation and primary numerical simulation.The Army's requirements for Tactical High-Energy Laser and key technical considerations were reviewed.Finally,the problems and challenges of Nautilus laser weapon were analyed and evaluated.
This paper briefly reviews the features of the tactical laser air defense weapons and the tests demontrated that Nautilus laser weapon could intercept short range missiles.We analyze the vulnerability of short range missiles for laser through estimation and primary numerical simulation.The Army's requirements for Tactical High-Energy Laser and key technical considerations were reviewed.Finally,the problems and challenges of Nautilus laser weapon were analyed and evaluated.
1997, 21(6): 326-329.
Abstract:
Based on the theory of electron impact excitation,the curves of electron impact-excitation cross sections q of S2(B-X) state can be calculated and the curves show that there are a threshold energy and a maximum value 10-16cm2 of electron impact excitation cross section q at the point of 1.8 time of threshold energy.According to the results,the laser threshold condition of discharge pumping S2 also is given out.The corrosion resisting and heat-resisting transverse pulse discharge apparatus of S2 is designed to provide the experimental system and the stable even glow discharge is obtained.The experimental research show that the small signal gain efficient at wavelength 419.4nm is 0.012cm-1.
Based on the theory of electron impact excitation,the curves of electron impact-excitation cross sections q of S2(B-X) state can be calculated and the curves show that there are a threshold energy and a maximum value 10-16cm2 of electron impact excitation cross section q at the point of 1.8 time of threshold energy.According to the results,the laser threshold condition of discharge pumping S2 also is given out.The corrosion resisting and heat-resisting transverse pulse discharge apparatus of S2 is designed to provide the experimental system and the stable even glow discharge is obtained.The experimental research show that the small signal gain efficient at wavelength 419.4nm is 0.012cm-1.
1997, 21(6): 330-333.
Abstract:
When a laser beam irradiates to the surface on a metal,the instantaneous energy accumulation makes a great number of metal atoms vapourous and form a shock wave propagating to the inner of materials.These reactions makes the microstructure and the propreties of the materials improved.In order to experimentally research the shock wave,the system composed of a quartz pressure transducer and a EMG201MSC excimer laser operating at 1060nm,pulse width 28ns,power density 1.06×108W/cm2,is designed to measure the laser shock wave on the surface of LY12CZ aluminum alloy,using instantaneous storage method and rolling method with a 2440 instantaneous storage oscilloscope.The experimental results show that the pressure of laser shock wave is MPa order.Finally,the attenuating equation of laser shock wave has the expression of P =13.4t-0.099,here the unit of P and t is MPa and ns respectively.
When a laser beam irradiates to the surface on a metal,the instantaneous energy accumulation makes a great number of metal atoms vapourous and form a shock wave propagating to the inner of materials.These reactions makes the microstructure and the propreties of the materials improved.In order to experimentally research the shock wave,the system composed of a quartz pressure transducer and a EMG201MSC excimer laser operating at 1060nm,pulse width 28ns,power density 1.06×108W/cm2,is designed to measure the laser shock wave on the surface of LY12CZ aluminum alloy,using instantaneous storage method and rolling method with a 2440 instantaneous storage oscilloscope.The experimental results show that the pressure of laser shock wave is MPa order.Finally,the attenuating equation of laser shock wave has the expression of P =13.4t-0.099,here the unit of P and t is MPa and ns respectively.
1997, 21(6): 333-338.
Abstract:
Fullerene-C60 ,as a kind of new materials used for laser protection,has been studied due to the fact that it is synthesixed and separated successfully in recent years.Optical limiting effect is based on the principles of reverse saturable absorption in C60 and it is one of the significant properties of this material.In this paper,some mechanisms,performances for optical limiting,new studying progresses of C60 are introduced and the application of C60 as an optical limiter material in future is discussed.
Fullerene-C60 ,as a kind of new materials used for laser protection,has been studied due to the fact that it is synthesixed and separated successfully in recent years.Optical limiting effect is based on the principles of reverse saturable absorption in C60 and it is one of the significant properties of this material.In this paper,some mechanisms,performances for optical limiting,new studying progresses of C60 are introduced and the application of C60 as an optical limiter material in future is discussed.
1997, 21(6): 339-342.
Abstract:
Nd:GdVO4 crystal is a laser crystal pumped by laser diodes.This paper reports the growing procedure and the properties of the crystal.We employed CZ method to grow the crystal at the condition of growing atmosphere of N2+He(30%～50%Vol) and add 0.5% of the component V2O5 over the burden calculation and modify technological procedure to correct the loss of volatile of V2O5.Using end-pumped by laser diode of pumped power 370mW,we have achieved the 13mW CW laser output power of Nd:GdVO4 laser,operating at TEM00mode and near 1060nm wavelength with 5% slop efficiency.The threshold pump power of the laser is 95mW.
Nd:GdVO4 crystal is a laser crystal pumped by laser diodes.This paper reports the growing procedure and the properties of the crystal.We employed CZ method to grow the crystal at the condition of growing atmosphere of N2+He(30%～50%Vol) and add 0.5% of the component V2O5 over the burden calculation and modify technological procedure to correct the loss of volatile of V2O5.Using end-pumped by laser diode of pumped power 370mW,we have achieved the 13mW CW laser output power of Nd:GdVO4 laser,operating at TEM00mode and near 1060nm wavelength with 5% slop efficiency.The threshold pump power of the laser is 95mW.
1997, 21(6): 343-345.
Abstract:
Based on a computer program of atmospheric transmissivity-CIRTRAN(Chinese Infrared Radiation TRAN smissivity program),the atmospheric transmissivity of Nd:YAG laser at λ=1.06μm propagating in a slant path is calculated for several various visibility and four regions of rural,urban,ocean,and desert.Analyzing and synthesizing the calculated results,one present a direct and simple expression.In comparison with three different measurement method and LOWTRAN7 a very well accuracy of the experession is demonstrated.
Based on a computer program of atmospheric transmissivity-CIRTRAN(Chinese Infrared Radiation TRAN smissivity program),the atmospheric transmissivity of Nd:YAG laser at λ=1.06μm propagating in a slant path is calculated for several various visibility and four regions of rural,urban,ocean,and desert.Analyzing and synthesizing the calculated results,one present a direct and simple expression.In comparison with three different measurement method and LOWTRAN7 a very well accuracy of the experession is demonstrated.
1997, 21(6): 346-349.
Abstract:
This paper describes a error slope curve measurement system for laser tracking.The system is composed of a semiconductor laser source,an array laser beam intensity distribution measurement instrument and a interface for data collecting and processing of laser tracking and ranging etc.The measurement accuracy of the system is high up to second grade.So,it becomes a main support method for measurement and test of laser tracking and raging equipment assembly,and give out the results of error slope curve.
This paper describes a error slope curve measurement system for laser tracking.The system is composed of a semiconductor laser source,an array laser beam intensity distribution measurement instrument and a interface for data collecting and processing of laser tracking and ranging etc.The measurement accuracy of the system is high up to second grade.So,it becomes a main support method for measurement and test of laser tracking and raging equipment assembly,and give out the results of error slope curve.
1997, 21(6): 349-351.
Abstract:
When Q-switched Nd:YAG laser radiation goes through a LiIO3 crystal,the stress wave will be induced for the laser radiation weak absorption of the crystal.In SHG of 1064nm laser radiation,the stress wave are enhanced and vary with the variation of phase mismatching angle.In this process,there exist the 1064nm fundamental laser radiation and 532nm SHG radiation in LiIO3 crystal,and the absorption to 532nm laser radiation is more serious than to 1064nm laser radiation.
When Q-switched Nd:YAG laser radiation goes through a LiIO3 crystal,the stress wave will be induced for the laser radiation weak absorption of the crystal.In SHG of 1064nm laser radiation,the stress wave are enhanced and vary with the variation of phase mismatching angle.In this process,there exist the 1064nm fundamental laser radiation and 532nm SHG radiation in LiIO3 crystal,and the absorption to 532nm laser radiation is more serious than to 1064nm laser radiation.
1997, 21(6): 352-354.
Abstract:
In this paper,it is found that there existed a little fluctuation in the weld depth at the frequency of 30～40Hz,when a mild steel had been welding by a laser beam.The laser welding is a very complex procedure,including absorption of the light energy,generation of plasma,heat conduction,et cetera.So we consider a relative simple model to simulate the laser energy Fresnel-absorption of the keyhole wall and stationery temperature field of the melting cell,based on the heat conduction of the workpiece.Finally,the analytical solution can be achieved and the simulations are consistent with experimental results.
In this paper,it is found that there existed a little fluctuation in the weld depth at the frequency of 30～40Hz,when a mild steel had been welding by a laser beam.The laser welding is a very complex procedure,including absorption of the light energy,generation of plasma,heat conduction,et cetera.So we consider a relative simple model to simulate the laser energy Fresnel-absorption of the keyhole wall and stationery temperature field of the melting cell,based on the heat conduction of the workpiece.Finally,the analytical solution can be achieved and the simulations are consistent with experimental results.
1997, 21(6): 354-357.
Abstract:
It is shown that a Fabry Perot-interferometer with small wedge angle or a Fizeau interferometer is illuminated by a collimated multiple longitudinal mode He-Ne laser beam,the spacing of adjacent fringes depends on the ratio r=d/L ,here d and L are the length of the interferometer and laser cavity.When r is a integral,the different order fringes corresponding to different modes are overlapped and the intensity of fringe is maximum and the fringe spacing represents λ/2.When r is fraction,r=N/M,N and M are both prime numbers,the fringe spacing is corresponding to λ/M.It is easy to get M= 10 for a long cavity He-Ne laser,the interferometric sensitivity is then 10 times that of M-Z interferometer.This interferometer can be applied to examining of the optical components with high precision and the measurement of low flow field.Some applications are presented in this paper.
It is shown that a Fabry Perot-interferometer with small wedge angle or a Fizeau interferometer is illuminated by a collimated multiple longitudinal mode He-Ne laser beam,the spacing of adjacent fringes depends on the ratio r=d/L ,here d and L are the length of the interferometer and laser cavity.When r is a integral,the different order fringes corresponding to different modes are overlapped and the intensity of fringe is maximum and the fringe spacing represents λ/2.When r is fraction,r=N/M,N and M are both prime numbers,the fringe spacing is corresponding to λ/M.It is easy to get M= 10 for a long cavity He-Ne laser,the interferometric sensitivity is then 10 times that of M-Z interferometer.This interferometer can be applied to examining of the optical components with high precision and the measurement of low flow field.Some applications are presented in this paper.
1997, 21(6): 358-360.
Abstract:
In this paper,we present a new discharge technique for exciting of the diffusion cooled CO2 lasers.Using a square wave discharge power source operating at 30kHz,a uniform stable glow discharge has been obtained in the volume of 5mm×30mm×446mm and the output power is 10W.
In this paper,we present a new discharge technique for exciting of the diffusion cooled CO2 lasers.Using a square wave discharge power source operating at 30kHz,a uniform stable glow discharge has been obtained in the volume of 5mm×30mm×446mm and the output power is 10W.
1997, 21(6): 360-364.
Abstract:
In this paper,some novel resonators used for high power diode pumped solid-state lasers in recent years,such as the rod imaging unstable resonator,near concentric unstable resonator and folded resonators,as well as the SBS phase conjugated MOPA system have been analyzed in depth,and the relevant techniques for achieving both high output power and good beam quality have been discussed.
In this paper,some novel resonators used for high power diode pumped solid-state lasers in recent years,such as the rod imaging unstable resonator,near concentric unstable resonator and folded resonators,as well as the SBS phase conjugated MOPA system have been analyzed in depth,and the relevant techniques for achieving both high output power and good beam quality have been discussed.
1997, 21(6): 365-368.
Abstract:
In this paper,we successfully utilize SnCl4·5H2O,FeCl3·6H2Oand pure alcohol for manufacturing the SnO2:Fe2O3 compound film(the Mole rate of Sn and Fe is 1:1) by using Sol-Gel method.At the region of 500-1200nm,the reflective spectrum of the compound film was measured.The measurement results show taht the relative reflective index drops and the peak of reflective curve shifts with the increase of acetone vapour concentration.According to the research,the compound film can be used for a gas sensing detector.
In this paper,we successfully utilize SnCl4·5H2O,FeCl3·6H2Oand pure alcohol for manufacturing the SnO2:Fe2O3 compound film(the Mole rate of Sn and Fe is 1:1) by using Sol-Gel method.At the region of 500-1200nm,the reflective spectrum of the compound film was measured.The measurement results show taht the relative reflective index drops and the peak of reflective curve shifts with the increase of acetone vapour concentration.According to the research,the compound film can be used for a gas sensing detector.
1997, 21(6): 369-371.
Abstract:
A weighted sum equation,which describes the relation between the diffractive efficiency and modulation transfer function of diffractive lenses,is derived.According to diffractive efficiency and optical transfer function,the total optical transfer function can be expressed with weighted sum of the series of order optical transfer functions of diffractive lights.The weighted factors are the diffractive efficiency.We employed the results to calculate MTF of various diffractive lens singlets and got consistent results with the literature [1].
A weighted sum equation,which describes the relation between the diffractive efficiency and modulation transfer function of diffractive lenses,is derived.According to diffractive efficiency and optical transfer function,the total optical transfer function can be expressed with weighted sum of the series of order optical transfer functions of diffractive lights.The weighted factors are the diffractive efficiency.We employed the results to calculate MTF of various diffractive lens singlets and got consistent results with the literature [1].
1997, 21(6): 372-375.
Abstract:
This paper demonstrates a high accurate controller of laser pulse position in time coordinate which bases on a 8098 programmable controller.This controller can output accurate and turnable trigger signals to lamps and Q-switchers to control the output of laser pulse by use of powerful ability of output/input and interruption of the 8098 programmable controller.By use of this controller the PPM modulation of the output of the laser pulse can be realized.This controller can control two laser to run synchronismly to obtain high peak power or to run alternately to obtain high repetition rate.
This paper demonstrates a high accurate controller of laser pulse position in time coordinate which bases on a 8098 programmable controller.This controller can output accurate and turnable trigger signals to lamps and Q-switchers to control the output of laser pulse by use of powerful ability of output/input and interruption of the 8098 programmable controller.By use of this controller the PPM modulation of the output of the laser pulse can be realized.This controller can control two laser to run synchronismly to obtain high peak power or to run alternately to obtain high repetition rate.
1997, 21(6): 375-379.
Abstract:
A numerical simulation model for the multisegment amplifier(MSA) with diffuse reflector has been built up by using ray-tracing and Monte Carlo methods.In our simulation,experimental data of the flashlamp radiation and Nd:glass absorption spectra have been considered.Numerical calculations have been performed,showing that both high transfer efficiency and good pumping energy distribution uniformity can be obtained in the use of the diffuse reflector.
A numerical simulation model for the multisegment amplifier(MSA) with diffuse reflector has been built up by using ray-tracing and Monte Carlo methods.In our simulation,experimental data of the flashlamp radiation and Nd:glass absorption spectra have been considered.Numerical calculations have been performed,showing that both high transfer efficiency and good pumping energy distribution uniformity can be obtained in the use of the diffuse reflector.
1997, 21(6): 380-382.
Abstract:
Starting from the imaging properties,the imaging transformation properties of the semi concave axicon is theoretically analyzed.Also the intensity distribution of the output beam is numerically calculated.The calculation has proved that the beam transformation through a semi concave axicon has the characteristics called "approximate diffraction-free beam".
Starting from the imaging properties,the imaging transformation properties of the semi concave axicon is theoretically analyzed.Also the intensity distribution of the output beam is numerically calculated.The calculation has proved that the beam transformation through a semi concave axicon has the characteristics called "approximate diffraction-free beam".
1997, 21(6): 383-384.
Abstract:
In this paper it has been reported on the low frequency preionization discharge supply,which is used for first high power CO laser in China developed by ourselves.The parameters of the supply,such as voltage output,current output and frequency,are 0～30kV,0～300mA and 1～20kHz,respectively.The preionization discharge supply has the feature of design simple,compact dimensions and has been successfully applied to the high power CO laser.
In this paper it has been reported on the low frequency preionization discharge supply,which is used for first high power CO laser in China developed by ourselves.The parameters of the supply,such as voltage output,current output and frequency,are 0～30kV,0～300mA and 1～20kHz,respectively.The preionization discharge supply has the feature of design simple,compact dimensions and has been successfully applied to the high power CO laser.
