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RSS1998 Vol. 22, No. 2
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1998, 22(2): 65-68.
[Abstract]
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Abstract:
According to theoretical analysis,the spectrum of the laser scintillation in atmosphere has relation to atmosphere transverse wind.So the detection and evaluation of the spectrum characteristics of laser scintillation can perform the remote sensing of atmosphere transversal wind.In our experimental system,the expression V=0.01715fc,here V is transversal wind speed and fc is turn point frequence of the laser scintillation spectrum,is derived.The experimental results are well agree with three cup anemometers.
According to theoretical analysis,the spectrum of the laser scintillation in atmosphere has relation to atmosphere transverse wind.So the detection and evaluation of the spectrum characteristics of laser scintillation can perform the remote sensing of atmosphere transversal wind.In our experimental system,the expression V=0.01715fc,here V is transversal wind speed and fc is turn point frequence of the laser scintillation spectrum,is derived.The experimental results are well agree with three cup anemometers.
1998, 22(2): 69-73.
Abstract:
When a light beam goes through the space flooded with passive disturbing materials,such as heavy smog,water-fog,aerosol etc.,the light wave will be greatly attenuated.We call the space the strong attenuation field.Our aim is to get the information of the small grains of 0.001mm size,but a conventional vedio camera can not take the clear pictures of the grains of the disturbing materials from the field,and can not provide the information about the parameters of single grain and the statistical characteristics of the group of the grains.In our system,the combination of CCD display technique and a special optical system named image pick-up microscopy,like the optical system of a microscope,is used to enlarge the image of the gain in the field.Then the picture can be transmitted over a long distance to process and to obtain the information of the characteristics of the grains.In this paper,the aberration of the optical system and manufacturing tolerance of the optical system have been analyzed.This is a new method to measure the passive disturbing materials in photoelectric countermeasure.
When a light beam goes through the space flooded with passive disturbing materials,such as heavy smog,water-fog,aerosol etc.,the light wave will be greatly attenuated.We call the space the strong attenuation field.Our aim is to get the information of the small grains of 0.001mm size,but a conventional vedio camera can not take the clear pictures of the grains of the disturbing materials from the field,and can not provide the information about the parameters of single grain and the statistical characteristics of the group of the grains.In our system,the combination of CCD display technique and a special optical system named image pick-up microscopy,like the optical system of a microscope,is used to enlarge the image of the gain in the field.Then the picture can be transmitted over a long distance to process and to obtain the information of the characteristics of the grains.In this paper,the aberration of the optical system and manufacturing tolerance of the optical system have been analyzed.This is a new method to measure the passive disturbing materials in photoelectric countermeasure.
1998, 22(2): 73-76.
Abstract:
A passive resonator laser gyroscope system composed of a reflective ring cavity is reported in this paper.The structure of the passive resonator is different from ordinary passive resonator:(1)there is only one lens in ring cavity to decrease the total loss of the cavity and to obtain much narrow resonative line width;(2)the intensity of the reflective light and the transmission light are minimum and maximum at the resonant centre respectively,so the SNR of reflective light can be greater than the SNR of transmission light;(3)the structure of the system is the compatible with passive resonator optical fiber gyroscope.The system has advanced performance,and its stability of drift is 1.7degree/hour in lab environment.The majoy reason causing drift is noise and closed loop control error in control circuit.
A passive resonator laser gyroscope system composed of a reflective ring cavity is reported in this paper.The structure of the passive resonator is different from ordinary passive resonator:(1)there is only one lens in ring cavity to decrease the total loss of the cavity and to obtain much narrow resonative line width;(2)the intensity of the reflective light and the transmission light are minimum and maximum at the resonant centre respectively,so the SNR of reflective light can be greater than the SNR of transmission light;(3)the structure of the system is the compatible with passive resonator optical fiber gyroscope.The system has advanced performance,and its stability of drift is 1.7degree/hour in lab environment.The majoy reason causing drift is noise and closed loop control error in control circuit.
1998, 22(2): 77-79.
Abstract:
The diamondlike thin films were prepared by irradiation on high pure graphite with a high energy density(1.178×109W/cm2) laser (XeCl 308nm) in 1×105Torr vacuum.The Raman spectra shows the thin film has the properties of diamond,the scatter peak is 1330cm-1.The IR spectra shows the thin film contained C-H bound,and the ratio of H to C is about 45%.The resistivity and optical energy gap of the thin film are 1.89×106Ω/cm and 1.55eV,respectively.
The diamondlike thin films were prepared by irradiation on high pure graphite with a high energy density(1.178×109W/cm2) laser (XeCl 308nm) in 1×105Torr vacuum.The Raman spectra shows the thin film has the properties of diamond,the scatter peak is 1330cm-1.The IR spectra shows the thin film contained C-H bound,and the ratio of H to C is about 45%.The resistivity and optical energy gap of the thin film are 1.89×106Ω/cm and 1.55eV,respectively.
1998, 22(2): 80-84.
Abstract:
A measurement system has been established to measure the size,concentration and velocity of particles in a horizontal air particle free jet from a nozzle of 42mm ID.The principles of evaluation of the particle size and average velocity,which is based on Mie scattering theory and transit timing technique,is presented in this paper.According to the evaluation,a series of the experiments are made to prove the agreement between the evaluation and experimental results,using the powder of aluminum oxide of 10～105μm.The measurement system has the features of the relatively simple optical system,low cast and high space discriminability.
A measurement system has been established to measure the size,concentration and velocity of particles in a horizontal air particle free jet from a nozzle of 42mm ID.The principles of evaluation of the particle size and average velocity,which is based on Mie scattering theory and transit timing technique,is presented in this paper.According to the evaluation,a series of the experiments are made to prove the agreement between the evaluation and experimental results,using the powder of aluminum oxide of 10～105μm.The measurement system has the features of the relatively simple optical system,low cast and high space discriminability.
1998, 22(2): 85-88.
Abstract:
The countermeasure system against the laser-guided weapon can be used to interfere with the laser-guided weapon and prevents the target from being attacked.In the paper,the principle,structure and some of the properties have been given.
The countermeasure system against the laser-guided weapon can be used to interfere with the laser-guided weapon and prevents the target from being attacked.In the paper,the principle,structure and some of the properties have been given.
1998, 22(2): 89-91.
Abstract:
Ordinary,the dye laser is used as a stokes light source in CARS thermometry.But the dye laser has the features of bad output stabilization and big size,so we employ OPO to replace the dye laser as the stokes light source of the CARS measurement system to realize the miniaturization of the system.This paper discusses the feasibility from the theoretical and practical analysis and points out that it is feasible at the range of less 2200K.
Ordinary,the dye laser is used as a stokes light source in CARS thermometry.But the dye laser has the features of bad output stabilization and big size,so we employ OPO to replace the dye laser as the stokes light source of the CARS measurement system to realize the miniaturization of the system.This paper discusses the feasibility from the theoretical and practical analysis and points out that it is feasible at the range of less 2200K.
1998, 22(2): 91-93.
Abstract:
Several kinds of laser-switch for laser cutting and carving machine have been designed and studied.Their properties have been discussed and compared respectively.
Several kinds of laser-switch for laser cutting and carving machine have been designed and studied.Their properties have been discussed and compared respectively.
1998, 22(2): 94-98.
Abstract:
The aluminum alloy is a wide used materials,especially in industrial products.But in laser welding,the many problem exist,such as inducing and stabilizing of keyholes,equivalent strength between base and welding seam,porosity et al.Based on the analysis on these problems,this paper points out the solutions to overcome these problems.The gas flow of gas shield welding should hold the situation of level flow at the pressure of 58.6Pa～78.0Pa,and the technique of wire fillet welding should be employed.
The aluminum alloy is a wide used materials,especially in industrial products.But in laser welding,the many problem exist,such as inducing and stabilizing of keyholes,equivalent strength between base and welding seam,porosity et al.Based on the analysis on these problems,this paper points out the solutions to overcome these problems.The gas flow of gas shield welding should hold the situation of level flow at the pressure of 58.6Pa～78.0Pa,and the technique of wire fillet welding should be employed.
1998, 22(2): 98-102.
Abstract:
Now the laser drilling is a useful technique in industry products.A very important problem is how to obtain the high quality deep hole drilling.Starting from the selection of laser parameters and the instantaneous energy balance in the gasification and melting process,the engineering design of deep hole drilling was presented,in this paper,and pointed the selection of ratio of depth and diameter,the design of the laser pulse shape.The calculation results are close to the experimental data.
Now the laser drilling is a useful technique in industry products.A very important problem is how to obtain the high quality deep hole drilling.Starting from the selection of laser parameters and the instantaneous energy balance in the gasification and melting process,the engineering design of deep hole drilling was presented,in this paper,and pointed the selection of ratio of depth and diameter,the design of the laser pulse shape.The calculation results are close to the experimental data.
Changes of laser beams with amplitude modulations and phase fluctuations passing through an aperture
1998, 22(2): 103-106.
Abstract:
In this paper,using the generalized Huygens Fresnel diffraction integral and statistical optics method,the propagation properties of laser beams with amplitude modulations and phase fluctuations passing through hard-edged and soft-edged apertures have been studied in detail.Numerical calculation results have illustrated that the intensity distributions in the near and far fields are dependent on the truncation parameter,Fresnel number of the system,and parameters of amplitude modulations and phase fluctuations.
In this paper,using the generalized Huygens Fresnel diffraction integral and statistical optics method,the propagation properties of laser beams with amplitude modulations and phase fluctuations passing through hard-edged and soft-edged apertures have been studied in detail.Numerical calculation results have illustrated that the intensity distributions in the near and far fields are dependent on the truncation parameter,Fresnel number of the system,and parameters of amplitude modulations and phase fluctuations.
1998, 22(2): 107-109.
Abstract:
This paper persents the some techniques and skills in art to enhance the quality of rainbow holograms and to produce a high quality slit-like parallel beam.The double-Gauss lens with 1:1 magnification is used in one step rainbow holography.
This paper persents the some techniques and skills in art to enhance the quality of rainbow holograms and to produce a high quality slit-like parallel beam.The double-Gauss lens with 1:1 magnification is used in one step rainbow holography.
1998, 22(2): 110-113.
Abstract:
Starting from Frantz Nodvik equation and using the pulse-sequence and thin-slab-medium models,the propagation properties of laser beams passing through a pulsed-laser multipass amplifier with diferent initial pulse fluences,the recovery parameters,gain distributions,losses and beam expanding factors between passes have been studied in detail.
Starting from Frantz Nodvik equation and using the pulse-sequence and thin-slab-medium models,the propagation properties of laser beams passing through a pulsed-laser multipass amplifier with diferent initial pulse fluences,the recovery parameters,gain distributions,losses and beam expanding factors between passes have been studied in detail.
1998, 22(2): 114-116.
Abstract:
About a coil being charged with a sine-alternation,there is a sine-walking-wave magnetic field.The distance between N and S of the field and the speed of the walking wave all can be regulated by changing the frequency of the sine-alternation.We get the result that the relativistic electron can get off shorter scattaning wavelength from the wiggler,the energy factor can be changed.Therefore the wiggler can be benefitical to the development of shorter wavelength and can contribute to the realization of the miniaturization of FEL.
About a coil being charged with a sine-alternation,there is a sine-walking-wave magnetic field.The distance between N and S of the field and the speed of the walking wave all can be regulated by changing the frequency of the sine-alternation.We get the result that the relativistic electron can get off shorter scattaning wavelength from the wiggler,the energy factor can be changed.Therefore the wiggler can be benefitical to the development of shorter wavelength and can contribute to the realization of the miniaturization of FEL.
1998, 22(2): 116-118.
Abstract:
Used optical interferometry,the dynamic process of thermal distortion of the silicon mirror was investigated experimentally,while the 2kW CO2 laser beam is used as incident source.The diplacement of surface of the silicon mirror is varying raplidly in the beginning of the distortion.For a silicon mirror,that is 70mm in diameter and 8mm in thickness,the maximum deflection introduced by thermal distortion is 0.76μm,when the absorbed laser power is 140W and the acting time is 4s.It is not an negligible problem to a high power short wavelength laser.
Used optical interferometry,the dynamic process of thermal distortion of the silicon mirror was investigated experimentally,while the 2kW CO2 laser beam is used as incident source.The diplacement of surface of the silicon mirror is varying raplidly in the beginning of the distortion.For a silicon mirror,that is 70mm in diameter and 8mm in thickness,the maximum deflection introduced by thermal distortion is 0.76μm,when the absorbed laser power is 140W and the acting time is 4s.It is not an negligible problem to a high power short wavelength laser.
1998, 22(2): 118-121.
Abstract:
A high power laser beam profile intensity measuring system using hole grating is introduced.The principle of hole grating sampler was analyzed.The HL CO2 laser focal irradiance distribution was measured with hole grating.The divergence and radius of laser beam were calculated.The beam quality can be valued by M2 factor.
A high power laser beam profile intensity measuring system using hole grating is introduced.The principle of hole grating sampler was analyzed.The HL CO2 laser focal irradiance distribution was measured with hole grating.The divergence and radius of laser beam were calculated.The beam quality can be valued by M2 factor.
1998, 22(2): 121-123.
Abstract:
In this paper,stable unstable resonators for planar diffusion cooled CO2 laser are analyzed theoretically.The relations between resonator parameters and mode parameters,which provide theoretical basis for the design of the resonators are deduced by the Fox Li algorithm.The results show that this kind of resonators not only can extract high laser power from the active region efficiently,but also can get a single elliptical astigmatic beam,which is close to the circular Gauss beam.
In this paper,stable unstable resonators for planar diffusion cooled CO2 laser are analyzed theoretically.The relations between resonator parameters and mode parameters,which provide theoretical basis for the design of the resonators are deduced by the Fox Li algorithm.The results show that this kind of resonators not only can extract high laser power from the active region efficiently,but also can get a single elliptical astigmatic beam,which is close to the circular Gauss beam.
1998, 22(2): 124-126.
Abstract:
For gas lasers a helical resonator with coaxial ring discharge structure is proposed,and the theoretical analysis is given.This resonator is composed of a helical reflecting mirror and a spherical reflecting mirror.The single laser beam can be effectively extracted.This resonator can be easily adjusted and is suitable for energy extraction from active medium.
For gas lasers a helical resonator with coaxial ring discharge structure is proposed,and the theoretical analysis is given.This resonator is composed of a helical reflecting mirror and a spherical reflecting mirror.The single laser beam can be effectively extracted.This resonator can be easily adjusted and is suitable for energy extraction from active medium.
1998, 22(2): 127-129.
Abstract:
A method of measuring the propagation mode near field of laser diodes is discussed,and the measured results of a practical device are given.It is shown that our method is simple and of high accuracy.
A method of measuring the propagation mode near field of laser diodes is discussed,and the measured results of a practical device are given.It is shown that our method is simple and of high accuracy.
1998, 22(2): 129-130.
Abstract:
A scheme of passive ranging of a laser source by single station based on the forward spontaneous Raman scattering in atmosphere is proposed,and the techniques to realize this scheme are discussed.
A scheme of passive ranging of a laser source by single station based on the forward spontaneous Raman scattering in atmosphere is proposed,and the techniques to realize this scheme are discussed.
