Map
WeChat
Email alert
RSS2002 Vol. 26, No. 4
Display Method:
2002, 26(4): 241-243,269.
[Abstract]
[PDF 868KB]
Abstract:
This article briefly describes the message and development status of the airborne laser.The operational link and its advanced infrared search and track senson,track lluminator laser and extreme low-light level sensor are analyzed.Finally,the weapon system's operational sequence is discussed.
This article briefly describes the message and development status of the airborne laser.The operational link and its advanced infrared search and track senson,track lluminator laser and extreme low-light level sensor are analyzed.Finally,the weapon system's operational sequence is discussed.
2002, 26(4): 244-245,249.
Abstract:
For first and third class boundary condition the temperature distribution of monocline laser crystal in a cross section perpendicular to rod axis during the lamp pumping process is calculated in this paper.It is shown that the temperature distribution exhibits radial parabola function and the isothermal line is circularity for first class boundary condition,whereas it is elliptic or hyperbolic function and the isothermal line is ellipse or hyperbola for third class boundary condition.The larger the difference between the principal thermal conductivity is and the lower the cooling efficiency of cooling agent is,the larger the difference with circularity is.Increasing cooling efficiency of cooling agent the difference with circularity will be decreasing.
For first and third class boundary condition the temperature distribution of monocline laser crystal in a cross section perpendicular to rod axis during the lamp pumping process is calculated in this paper.It is shown that the temperature distribution exhibits radial parabola function and the isothermal line is circularity for first class boundary condition,whereas it is elliptic or hyperbolic function and the isothermal line is ellipse or hyperbola for third class boundary condition.The larger the difference between the principal thermal conductivity is and the lower the cooling efficiency of cooling agent is,the larger the difference with circularity is.Increasing cooling efficiency of cooling agent the difference with circularity will be decreasing.
2002, 26(4): 246-249.
Abstract:
The microstructure,phase,element distribution and microhardness have been analyzed with the aid of microscope,X-ray diffraction,electron probe and microhardness-tester.It is shown that there are different solidification parameters for different zones in cladding layer,hence the different microstructure.Introduction of the ceramic made the microstructure very fine.Meanwhile,the growth direction of the dendrite is various because of the presence of the ceramic particle.It has been observed that the disperse Al2O3 and TiB2 with the size of sub-micrometer formed in the grains and unreacted B2O3,TiO2 are distributed along the grain boundary.There is a ceramic density-gradient distribution along the depth of the cladding layer.The highest value of microhardness was 434HV 0.2.Experimental results show that the γ-Ni,γ',Al2O3 and TiB2 are the dominant phases in the cladding zone.The microstructure and hardness of the cladding layer are governed by the laser processing parameters and the coating's chemical composition.The hardness and the wear property of the layer are significantly enhanced due to the present of ceramic in the coating.
The microstructure,phase,element distribution and microhardness have been analyzed with the aid of microscope,X-ray diffraction,electron probe and microhardness-tester.It is shown that there are different solidification parameters for different zones in cladding layer,hence the different microstructure.Introduction of the ceramic made the microstructure very fine.Meanwhile,the growth direction of the dendrite is various because of the presence of the ceramic particle.It has been observed that the disperse Al2O3 and TiB2 with the size of sub-micrometer formed in the grains and unreacted B2O3,TiO2 are distributed along the grain boundary.There is a ceramic density-gradient distribution along the depth of the cladding layer.The highest value of microhardness was 434HV 0.2.Experimental results show that the γ-Ni,γ',Al2O3 and TiB2 are the dominant phases in the cladding zone.The microstructure and hardness of the cladding layer are governed by the laser processing parameters and the coating's chemical composition.The hardness and the wear property of the layer are significantly enhanced due to the present of ceramic in the coating.
2002, 26(4): 250-251,254.
Abstract:
In this paper,the experimental results of Si wafer cutting by 193nm excimer laser are reported.By using cylinder focus system and "thermal-splits" technique,less than 15μm cutting gap with 5μm fluctuation of cutting edge are obtained.
In this paper,the experimental results of Si wafer cutting by 193nm excimer laser are reported.By using cylinder focus system and "thermal-splits" technique,less than 15μm cutting gap with 5μm fluctuation of cutting edge are obtained.
2002, 26(4): 252-254.
Abstract:
A kind of coating used in the pretreatment coating of CO2 laser surface modification is studied.The thermal penetration depth,hardness and surface coarseness of the hardened layer have been examined with the coating used in laser surface hardening treatment.The experiment results indicate that the coating is of merits because it has high absorption rate,high conductivity and good thermochemical stability.The coating has no erosion,poison,pollution and sputtering.It is low-cost,harmless,and easy to remove.It completely meets the demand of laser hardening.
A kind of coating used in the pretreatment coating of CO2 laser surface modification is studied.The thermal penetration depth,hardness and surface coarseness of the hardened layer have been examined with the coating used in laser surface hardening treatment.The experiment results indicate that the coating is of merits because it has high absorption rate,high conductivity and good thermochemical stability.The coating has no erosion,poison,pollution and sputtering.It is low-cost,harmless,and easy to remove.It completely meets the demand of laser hardening.
2002, 26(4): 255-257,261.
Abstract:
This paper discusses the significance of optical offset frequency locking techniques,then give the overview of their current development home and abroad,and finally gives a detailed introduction to different frequency discriminating methods and their advantages and disadvantages.
This paper discusses the significance of optical offset frequency locking techniques,then give the overview of their current development home and abroad,and finally gives a detailed introduction to different frequency discriminating methods and their advantages and disadvantages.
2002, 26(4): 258-261.
Abstract:
The mechanism of interaction between laser and liquid material has been persistently received much attention in a variety of fields,such as medicine,industry.This interaction is a very complex one,accompanying optical,acoustic,mechanical effect and so on.In recent years,study about the laser-induced optical breakdown mechanism,shock wave emission and cavitation bubble dynamics,not only in theory,but also by experiments,has developed quickly.This paper mainly presents situation,development and some unsolved problems about the interactional mechanism.
The mechanism of interaction between laser and liquid material has been persistently received much attention in a variety of fields,such as medicine,industry.This interaction is a very complex one,accompanying optical,acoustic,mechanical effect and so on.In recent years,study about the laser-induced optical breakdown mechanism,shock wave emission and cavitation bubble dynamics,not only in theory,but also by experiments,has developed quickly.This paper mainly presents situation,development and some unsolved problems about the interactional mechanism.
2002, 26(4): 262-263,289.
Abstract:
Laser hardening of 40Cr has been carried out with a 5kW CW CO2 laser,the effects of laser technical parameters on hardened depth are discussed.The results indicate that the hardened depth increases with increasing laser power or overlap of dimension of laser beam and decreasing speed and that scanning speed is more important to hardened depth than laser power.In a range of laser hardening technical parameters:laser beam diameter:3mm,laser power:1000～1200W,scanning speed:15～30mm/s,overlap of dimension of laser beam:1.0～1.5mm,a hardened depth of 40Cr no less than 0.35mm can be obtained.
Laser hardening of 40Cr has been carried out with a 5kW CW CO2 laser,the effects of laser technical parameters on hardened depth are discussed.The results indicate that the hardened depth increases with increasing laser power or overlap of dimension of laser beam and decreasing speed and that scanning speed is more important to hardened depth than laser power.In a range of laser hardening technical parameters:laser beam diameter:3mm,laser power:1000～1200W,scanning speed:15～30mm/s,overlap of dimension of laser beam:1.0～1.5mm,a hardened depth of 40Cr no less than 0.35mm can be obtained.
2002, 26(4): 264-266.
Abstract:
Since Epstein realized the energy conversion between light and heat and got the net cooling capacity in 1995,this refrigeration method has been developed very rapidly because of its merits,such as mini volume,light weight,free electromagnetic radiation,non-noise,high reliability.In the meantime,anti-Stokes fluorescent cooling has luring future in military,aerospace,satellite,micro-electronics,cryogenic physics and engineering.The basic thermodynamic laws are utilized to analyze the conversion depth about heat energy into light radiation in detail;the definitions of light effective temperature and thermodynamic conversion efficiency are introduced.Then a formula to calculate the thermodynamic upper efficiency limit has been derived,which can provide a design guide rule to produce the laser cooling machines.
Since Epstein realized the energy conversion between light and heat and got the net cooling capacity in 1995,this refrigeration method has been developed very rapidly because of its merits,such as mini volume,light weight,free electromagnetic radiation,non-noise,high reliability.In the meantime,anti-Stokes fluorescent cooling has luring future in military,aerospace,satellite,micro-electronics,cryogenic physics and engineering.The basic thermodynamic laws are utilized to analyze the conversion depth about heat energy into light radiation in detail;the definitions of light effective temperature and thermodynamic conversion efficiency are introduced.Then a formula to calculate the thermodynamic upper efficiency limit has been derived,which can provide a design guide rule to produce the laser cooling machines.
2002, 26(4): 267-269.
Abstract:
In the paper,the pixelated holographic display method is presented and tested successfully through experiment.The new method can solve the problems of light source,space requirement and alignment.
In the paper,the pixelated holographic display method is presented and tested successfully through experiment.The new method can solve the problems of light source,space requirement and alignment.
2002, 26(4): 270-272.
Abstract:
In this paper,we discuss the experimental results of intracavity CdTe electro-optical Q-switch for RF excited waveguide CO2 lasers with frequency-stable and line-selected,which is used in an active imaging radar.The loss of CdTe in the laser has been calculated and the results are consistent with that of experiment.We also discuss the thermal stability of the CdTe crystal and 1/4 waveplate,as well as the pulse characteristic of CdTe Q-switch at various instances.This laser has EH11 output mode with 150ns pulse width(FWHM),360W peak power at 41.67kHz pulse repetition frequency.
In this paper,we discuss the experimental results of intracavity CdTe electro-optical Q-switch for RF excited waveguide CO2 lasers with frequency-stable and line-selected,which is used in an active imaging radar.The loss of CdTe in the laser has been calculated and the results are consistent with that of experiment.We also discuss the thermal stability of the CdTe crystal and 1/4 waveplate,as well as the pulse characteristic of CdTe Q-switch at various instances.This laser has EH11 output mode with 150ns pulse width(FWHM),360W peak power at 41.67kHz pulse repetition frequency.
2002, 26(4): 273-276.
Abstract:
This paper introduces the basic composition,development plan and its progress,technical challenges of the researching and developing tactical high energy laser(THEL),shipbased high energy laser weapon system(HELWS) and airborne tactical laser(ATL).
This paper introduces the basic composition,development plan and its progress,technical challenges of the researching and developing tactical high energy laser(THEL),shipbased high energy laser weapon system(HELWS) and airborne tactical laser(ATL).
2002, 26(4): 277-278.
Abstract:
The algorithm of Gaussian fitting and an ameliorated on are presented.The experiment results show that the fitting curve approximates to the original experiment data,the intensity of saturation area can be estimated.
The algorithm of Gaussian fitting and an ameliorated on are presented.The experiment results show that the fitting curve approximates to the original experiment data,the intensity of saturation area can be estimated.
2002, 26(4): 279-283.
Abstract:
We present a theoretical analysis of temperature effects on the stability of screening-photovoltaic spatial bright solitons in biased photovoltaic-photorefractive materials.A stable screening-photovoltaic bright soliton formed at a temperature is stable against small perturbations when the temperature changes in a regime by name the stable temperature regime whereas tends to be unstable when the temperature exceeds the regime.An unstable optical solitary beam can evolve into a stable screening-photovoltaic bright soliton by adjusting the crystal temperature.
We present a theoretical analysis of temperature effects on the stability of screening-photovoltaic spatial bright solitons in biased photovoltaic-photorefractive materials.A stable screening-photovoltaic bright soliton formed at a temperature is stable against small perturbations when the temperature changes in a regime by name the stable temperature regime whereas tends to be unstable when the temperature exceeds the regime.An unstable optical solitary beam can evolve into a stable screening-photovoltaic bright soliton by adjusting the crystal temperature.
2002, 26(4): 284-286.
Abstract:
Laser field across the diffraction-limited optical system has been numerically investigated by separating an optical system as some serial subsystems along the diffraction-limited interface.The simulated results of Gaussian laser beams are presented in the paper.
Laser field across the diffraction-limited optical system has been numerically investigated by separating an optical system as some serial subsystems along the diffraction-limited interface.The simulated results of Gaussian laser beams are presented in the paper.
2002, 26(4): 287-289.
Abstract:
The rate equation has been used to discover the reason of pulse distortion caused by the multi-pulses.The way to reduce the distortion of pulse has been discussed.
The rate equation has been used to discover the reason of pulse distortion caused by the multi-pulses.The way to reduce the distortion of pulse has been discussed.
2002, 26(4): 290-291,294.
Abstract:
Experimental studies indicate that in high frequency Ca lasers,laser pulse may be ahead of schedule,but the delay time of CuBr laser pulse is related with temperature and frequency,the pulse can occur at the post edge of the current pulse.The phenomenon is explained in the paper.
Experimental studies indicate that in high frequency Ca lasers,laser pulse may be ahead of schedule,but the delay time of CuBr laser pulse is related with temperature and frequency,the pulse can occur at the post edge of the current pulse.The phenomenon is explained in the paper.
2002, 26(4): 292-294.
Abstract:
According to the structure and function characteristics of laser rangefinders,a method is put forward to constitute a fault dictionary and diagnose faults for laser rangefinders based on Bayes decision-making theory.In general,the method can be used to diagnose ordinary faults and give decision-making in maintenance for laser rangefinders,which have enough maintenance experience.
According to the structure and function characteristics of laser rangefinders,a method is put forward to constitute a fault dictionary and diagnose faults for laser rangefinders based on Bayes decision-making theory.In general,the method can be used to diagnose ordinary faults and give decision-making in maintenance for laser rangefinders,which have enough maintenance experience.
2002, 26(4): 295-296,317.
Abstract:
The processing methods of vector figure and lattice image in the laser marking system are introduced in the paper.These methods can increase the marking precision and marking speed.
The processing methods of vector figure and lattice image in the laser marking system are introduced in the paper.These methods can increase the marking precision and marking speed.
2002, 26(4): 297-299,302.
Abstract:
A method of coherent combination of laser beams has been proposed.Based on the conjugate gradient algorithm,the two-dimension numerical simulation with a 16-level phase quantized diffraction optical element(DOE) shows that the combination efficiency is about 94.8%,with an error less than 2.4%.Error analysis has been performed.
A method of coherent combination of laser beams has been proposed.Based on the conjugate gradient algorithm,the two-dimension numerical simulation with a 16-level phase quantized diffraction optical element(DOE) shows that the combination efficiency is about 94.8%,with an error less than 2.4%.Error analysis has been performed.
2002, 26(4): 300-302.
Abstract:
Based on a numerical model cesium atomic clock designed before,the influence of atomic velocity distribution consisting of two peaks and three peaks has been studied respectively.The main characteristics of the microwave spectra under this circumstance has been analyzed and compared with the reported phenomenon in NBS-4 magnetic state-selection cesium clock and the recent experimental result of an optically pumped small cesium clock in Peking University.The characteristic of the microwave spectra in the case of atomic velocity distribution consisting of two peaks has been verified.
Based on a numerical model cesium atomic clock designed before,the influence of atomic velocity distribution consisting of two peaks and three peaks has been studied respectively.The main characteristics of the microwave spectra under this circumstance has been analyzed and compared with the reported phenomenon in NBS-4 magnetic state-selection cesium clock and the recent experimental result of an optically pumped small cesium clock in Peking University.The characteristic of the microwave spectra in the case of atomic velocity distribution consisting of two peaks has been verified.
2002, 26(4): 303-305.
Abstract:
Most laser particle sizer based on light scattering adopt such a structure in which the sample cell is put behind the Fourier lens.The angle range of scattered light received by a ring of the concentric-ring-shipped photoelectric detector is determined according to the Fourier optics.In accordance with such determaination,the reason of resulting error under large-angle scattering has been analyzed,the magnitude of the errors has been calculated,and the effect on particle sizing has been discussed.The formula,which is proper to determining the angle range of scattered light received by every detecting ring,have been derived.
Most laser particle sizer based on light scattering adopt such a structure in which the sample cell is put behind the Fourier lens.The angle range of scattered light received by a ring of the concentric-ring-shipped photoelectric detector is determined according to the Fourier optics.In accordance with such determaination,the reason of resulting error under large-angle scattering has been analyzed,the magnitude of the errors has been calculated,and the effect on particle sizing has been discussed.The formula,which is proper to determining the angle range of scattered light received by every detecting ring,have been derived.
2002, 26(4): 306-307,310.
Abstract:
In the paper,the solution of Bessel-modulated Gaussian beams(QBG beams) with quadratic radial dependence is derived by solving the paraxial wave equation derives radial dependence.The propagation property in free space is studied.
In the paper,the solution of Bessel-modulated Gaussian beams(QBG beams) with quadratic radial dependence is derived by solving the paraxial wave equation derives radial dependence.The propagation property in free space is studied.
2002, 26(4): 308-310.
Abstract:
A new method of position detector with PSD is described.Based on the theoretical model of this technique,numerical simulation is carried out and corresponding circuit is designed.The test result is accordant with theoretical model.With this technique,we can measure more sensitively,anti-jamming and low cost.
A new method of position detector with PSD is described.Based on the theoretical model of this technique,numerical simulation is carried out and corresponding circuit is designed.The test result is accordant with theoretical model.With this technique,we can measure more sensitively,anti-jamming and low cost.
2002, 26(4): 311-313.
Abstract:
The Fraunhofer diffraction of Gaussian beam by a circular aperture are derived and are compared to that of plane wave in this paper.Through theoretical and numerical analyze,it shows that both results are the similar while the radius of Gaussian beam is much larger than the radius of circlar aperture,otherwise,they are different.Then the Fraunhofer diffraction of Gaussian beam by a group of particles with the same size are given.
The Fraunhofer diffraction of Gaussian beam by a circular aperture are derived and are compared to that of plane wave in this paper.Through theoretical and numerical analyze,it shows that both results are the similar while the radius of Gaussian beam is much larger than the radius of circlar aperture,otherwise,they are different.Then the Fraunhofer diffraction of Gaussian beam by a group of particles with the same size are given.
2002, 26(4): 314-317.
Abstract:
In this paper,we introduce present research situation and question of beam amplification of stimulated Brillouin scattering and point out its development prospect.
In this paper,we introduce present research situation and question of beam amplification of stimulated Brillouin scattering and point out its development prospect.
2002, 26(4): 318-320.
Abstract:
In this paper,we consider the general situation in which a amplitude of the point light source may be modulated at frequency Ω.According to our experiment,we study the diffusing equation in theory.And get the results of relationship between the flux and uniform absorption coefficients.This result can directly be used in experiment about image in multiple-scattering media.
In this paper,we consider the general situation in which a amplitude of the point light source may be modulated at frequency Ω.According to our experiment,we study the diffusing equation in theory.And get the results of relationship between the flux and uniform absorption coefficients.This result can directly be used in experiment about image in multiple-scattering media.
