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RSS2002 Vol. 26, No. 3
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2002, 26(3): 161-164.
[Abstract]
[PDF 1049KB]
Abstract:
The advantages of laser bending over traditional forming processes are being recognized.However,the biggest problem in current appliccation is lack of information of process parameters to form predefined final shapes.Numerical simulation is a useful way in this field.Several recent mathematical models of laser bending are examined and key areas for the future are suggested in the paper.
The advantages of laser bending over traditional forming processes are being recognized.However,the biggest problem in current appliccation is lack of information of process parameters to form predefined final shapes.Numerical simulation is a useful way in this field.Several recent mathematical models of laser bending are examined and key areas for the future are suggested in the paper.
2002, 26(3): 165-169.
Abstract:
Recent developments of phase dislocation and branch point in optics are reviewed.They include the theory and measurement study of the function description of wave front that has branch point,the calulation of hidden phase,the detection and density of the branch point,the restructure method of hidden phase in adaptive optics.
Recent developments of phase dislocation and branch point in optics are reviewed.They include the theory and measurement study of the function description of wave front that has branch point,the calulation of hidden phase,the detection and density of the branch point,the restructure method of hidden phase in adaptive optics.
2002, 26(3): 170-173.
Abstract:
On the basis of the analysis of the feeding pattern of the coating material,its behavior in the laser beam and the attenuation of laser beam by particle cloud during the process of laser coating with automatic powder feeding,the methods to calculate the interaction efficiency η of laser and particle speed v0 are presented.The equation of the interaction efficiency η is established and expressions relating the parameters in the processes are obtained.The factors affecting the interaction efficiency η is studied carefully.The interaction efficiency η is calculated by means of metallography.A reasonable explanation about why a maximum interaction efficiency η is observed with the scanning speed varies is presented.
On the basis of the analysis of the feeding pattern of the coating material,its behavior in the laser beam and the attenuation of laser beam by particle cloud during the process of laser coating with automatic powder feeding,the methods to calculate the interaction efficiency η of laser and particle speed v0 are presented.The equation of the interaction efficiency η is established and expressions relating the parameters in the processes are obtained.The factors affecting the interaction efficiency η is studied carefully.The interaction efficiency η is calculated by means of metallography.A reasonable explanation about why a maximum interaction efficiency η is observed with the scanning speed varies is presented.
2002, 26(3): 174-176.
Abstract:
An approximate analytical propagation equation of Laguerre Gaussian beams passing through a paraxial ABCD optical system with hard edge aperture is derived,where the circa function is expanded into a finite sum of complex Gaussian functions.Numerical examples are given to illustrate the application of the propagation equation and discrepancies in use of the approximate formula are discussed.
An approximate analytical propagation equation of Laguerre Gaussian beams passing through a paraxial ABCD optical system with hard edge aperture is derived,where the circa function is expanded into a finite sum of complex Gaussian functions.Numerical examples are given to illustrate the application of the propagation equation and discrepancies in use of the approximate formula are discussed.
2002, 26(3): 177-179.
Abstract:
In this paper,the laser hardening technological parameters and the nigrescence technology with surface oxidation have been studied on tiny workpieces of 4Cr13 stainless steel,while the influences of the laser technology and various lapping ratios on hardness,depth and microstructures of the hardening layer have been explored. The results show that the surface of Φ10mm×8mm workpieces can be hardened by means of proper laser technology,meanwhile,an uniform hardened layer can be achieved with surface hardness of 42 HRC～45HRC at 40 percent lapping ratio,which can meet the designed requirement.
In this paper,the laser hardening technological parameters and the nigrescence technology with surface oxidation have been studied on tiny workpieces of 4Cr13 stainless steel,while the influences of the laser technology and various lapping ratios on hardness,depth and microstructures of the hardening layer have been explored. The results show that the surface of Φ10mm×8mm workpieces can be hardened by means of proper laser technology,meanwhile,an uniform hardened layer can be achieved with surface hardness of 42 HRC～45HRC at 40 percent lapping ratio,which can meet the designed requirement.
2002, 26(3): 180-182.
Abstract:
Based on solution of the rate equation of semiconductor lasers (LDs),the dynamic characteristics of grating tuned bistabe external cavity LDs (ECLDs) have been described. The effects of the tuning angle of the grating on the transient process have been discussed. It is found that a narrow and strong pulse may be observed before the switched off mode dies out when the output of the bistable ECLD jumps up. This phenomenon does not appear in the jump down process. In addition,the ECLD settles down more quickly for the jump up process.
Based on solution of the rate equation of semiconductor lasers (LDs),the dynamic characteristics of grating tuned bistabe external cavity LDs (ECLDs) have been described. The effects of the tuning angle of the grating on the transient process have been discussed. It is found that a narrow and strong pulse may be observed before the switched off mode dies out when the output of the bistable ECLD jumps up. This phenomenon does not appear in the jump down process. In addition,the ECLD settles down more quickly for the jump up process.
2002, 26(3): 183-185.
Abstract:
The cast WCp/Ni base alloy gradient composite coating is clad onto 40Cr tempered steel by means of broadband laser.The microstructure and properties of the coating have been tested and analyzed.A preliminary discussion of the mechanism to improve the coating's properties is also made.
The cast WCp/Ni base alloy gradient composite coating is clad onto 40Cr tempered steel by means of broadband laser.The microstructure and properties of the coating have been tested and analyzed.A preliminary discussion of the mechanism to improve the coating's properties is also made.
2002, 26(3): 186-188.
Abstract:
The shape of the particles in 3D can be present in 2D upon EPO theory,so a function which presents the distribution of the shape of particles is put forward in this paper.The other function T(f) that presents the inference affection of the shape is also calculated in the case of Gaussian scattering field.The result of the calculation conforms to Mie scattering of the spherical particles.
The shape of the particles in 3D can be present in 2D upon EPO theory,so a function which presents the distribution of the shape of particles is put forward in this paper.The other function T(f) that presents the inference affection of the shape is also calculated in the case of Gaussian scattering field.The result of the calculation conforms to Mie scattering of the spherical particles.
2002, 26(3): 189-191.
Abstract:
Compact tension(CT) specimens of superalloy with thickness of 1.5mm and a high strength steel sheet with thickness of 1.7mm are processed by laser shock,with three spots with diameter of 6mm overlapped along the extension line of precut crack.The fatigue crack growth rates of laser shock processed specimens are compared with those without LSP.The results show that effects of laser shock strengthening have much difference along the crack growth line,the fatigure growth rates can not be fitted by the Paris formula,but laser shock processing can decrease the fatigue crack growth rate in whole distincctly.
Compact tension(CT) specimens of superalloy with thickness of 1.5mm and a high strength steel sheet with thickness of 1.7mm are processed by laser shock,with three spots with diameter of 6mm overlapped along the extension line of precut crack.The fatigue crack growth rates of laser shock processed specimens are compared with those without LSP.The results show that effects of laser shock strengthening have much difference along the crack growth line,the fatigure growth rates can not be fitted by the Paris formula,but laser shock processing can decrease the fatigue crack growth rate in whole distincctly.
2002, 26(3): 192-193.
Abstract:
A new light beam,termed as cosh squared Gaussian beam,which can be used to solve the paraxial wave equation for propagation in complex optical systems,has been introduced.Then,the propagating features through the first order optical system are studied.
A new light beam,termed as cosh squared Gaussian beam,which can be used to solve the paraxial wave equation for propagation in complex optical systems,has been introduced.Then,the propagating features through the first order optical system are studied.
2002, 26(3): 194-197.
Abstract:
The techniques of tunable dispersion compensation are discussed in the paper.The mechanism,properties and performance for several techniques of tunable dispersion compensation are analyzed and compared.
The techniques of tunable dispersion compensation are discussed in the paper.The mechanism,properties and performance for several techniques of tunable dispersion compensation are analyzed and compared.
2002, 26(3): 198-200.
Abstract:
A great deal of waste heat from a space based laser must be rejected to outer space environment.Conventional thermal control systems such as heat pump,single phase or two phase pumped fluid loops or expendable water vaporizer are not very well suited for heat rejection requirements due to excessive mass,value and/or power consumption.A feasibility study on an integrated radiate cooling system with ice storage for the thermal management of a space based laser is assessed on the basis of compact and lightweight.The analytical results show that the integrated scheme can meet the waste heat rejection requirements and greatly reduce the total mass and volume of the thermal management system,and show its promising prospects in future space based lasers' thermal management systems.
A great deal of waste heat from a space based laser must be rejected to outer space environment.Conventional thermal control systems such as heat pump,single phase or two phase pumped fluid loops or expendable water vaporizer are not very well suited for heat rejection requirements due to excessive mass,value and/or power consumption.A feasibility study on an integrated radiate cooling system with ice storage for the thermal management of a space based laser is assessed on the basis of compact and lightweight.The analytical results show that the integrated scheme can meet the waste heat rejection requirements and greatly reduce the total mass and volume of the thermal management system,and show its promising prospects in future space based lasers' thermal management systems.
2002, 26(3): 201-203.
Abstract:
A compact high efficient all solid state 1.57μm eye safe intracavity optical parametric oscillator is developed.The pump laser is a diode side pumped Q switched Nd:YAG laser.The OPO acts as a single resonator for the signal wave.In experiment,the highest signal output of 15mJ/pulse at 20Hz is obtained with pulse width of 7ns and the wall plug efficiency up to 2.6%.
A compact high efficient all solid state 1.57μm eye safe intracavity optical parametric oscillator is developed.The pump laser is a diode side pumped Q switched Nd:YAG laser.The OPO acts as a single resonator for the signal wave.In experiment,the highest signal output of 15mJ/pulse at 20Hz is obtained with pulse width of 7ns and the wall plug efficiency up to 2.6%.
2002, 26(3): 204-207.
Abstract:
Laser cladding is a high new technique developing fast among the most modern techniques of surface modification and manufacture.The development of laser cladding techniques and application is introduced,then laser cladding materials and design techniques are reviewed,and finally some interest problems are brought forward.
Laser cladding is a high new technique developing fast among the most modern techniques of surface modification and manufacture.The development of laser cladding techniques and application is introduced,then laser cladding materials and design techniques are reviewed,and finally some interest problems are brought forward.
2002, 26(3): 208-210.
Abstract:
Theoretical and experimental study on the optical damage mechanism of (Nd,Ce):YAG Raman shifting laser in high pressure CH4 gas with compound output mirror and internal cavity has been reported.The design scheme to solve the optical damage of Raman shifting laser with high repetition frequency has been proposed.
Theoretical and experimental study on the optical damage mechanism of (Nd,Ce):YAG Raman shifting laser in high pressure CH4 gas with compound output mirror and internal cavity has been reported.The design scheme to solve the optical damage of Raman shifting laser with high repetition frequency has been proposed.
2002, 26(3): 211-213.
Abstract:
It reveals the principle of compensation PMD by nonlinearly coupled equation with in line synchronous modulation.The compensation of PMD by in line synchronous modulation at 40Gbit/s is computed.The maximum transmission distance is increased three times and the property of transmission system is improved by in line synchronous modulation.The PMD is compensated effectively by in line synchronous modulation.
It reveals the principle of compensation PMD by nonlinearly coupled equation with in line synchronous modulation.The compensation of PMD by in line synchronous modulation at 40Gbit/s is computed.The maximum transmission distance is increased three times and the property of transmission system is improved by in line synchronous modulation.The PMD is compensated effectively by in line synchronous modulation.
2002, 26(3): 214-216.
Abstract:
On the basis of the systematic analysis and study on the arithmetic using scanning laser to measure the position of a aircraft in the process of anatomists,the arithmetic using four reflectors to measure the pose of the aircraft is put forward.An experimental system has been set up,the time interval of the optical signals is measured and the distance and azimuth of the aircraft is calculated.The experimental results are accordant with the theoretically calculated ones.
On the basis of the systematic analysis and study on the arithmetic using scanning laser to measure the position of a aircraft in the process of anatomists,the arithmetic using four reflectors to measure the pose of the aircraft is put forward.An experimental system has been set up,the time interval of the optical signals is measured and the distance and azimuth of the aircraft is calculated.The experimental results are accordant with the theoretically calculated ones.
2002, 26(3): 217-220.
Abstract:
In the paper,mid infrared optical parametric oscillator based on birefringent nonlinear crystals such as KTP,KTA,AgGaS2,AgGaSe2and ZnGeP2 are introduced and discussed.Finally quasi phase matcched periodically poled LiNbO3 OPO is analyzed that can produce quasi continuous and continuous waves in the range of 3～5μm.
In the paper,mid infrared optical parametric oscillator based on birefringent nonlinear crystals such as KTP,KTA,AgGaS2,AgGaSe2and ZnGeP2 are introduced and discussed.Finally quasi phase matcched periodically poled LiNbO3 OPO is analyzed that can produce quasi continuous and continuous waves in the range of 3～5μm.
2002, 26(3): 221-222.
Abstract:
Based on a simplified model of gain region,the propagation and amplification of X ray within cylindrical plasma with linear electron density profile are studied with geometrical optical approximation.The reflection angle and the relation between the output intensity and deflection angle are put forward.
Based on a simplified model of gain region,the propagation and amplification of X ray within cylindrical plasma with linear electron density profile are studied with geometrical optical approximation.The reflection angle and the relation between the output intensity and deflection angle are put forward.
2002, 26(3): 223-224.
Abstract:
The key technique of on line laser quenching manufacture for automobile engine cylinder is studied and laser resonator construction,optical elements and cooling technique are improved.Aqua metal oxide colloid absorbency is developed,to form absorb light coat on line is realized with the help of precision hole spurt out method.Based on the above technique,an engine cylinder laser quenching numerical control machine is developed.The machine is an optical,mechanical,electrical modular system.It is the first time for automobile engine cylinder is quenched on line in China.
The key technique of on line laser quenching manufacture for automobile engine cylinder is studied and laser resonator construction,optical elements and cooling technique are improved.Aqua metal oxide colloid absorbency is developed,to form absorb light coat on line is realized with the help of precision hole spurt out method.Based on the above technique,an engine cylinder laser quenching numerical control machine is developed.The machine is an optical,mechanical,electrical modular system.It is the first time for automobile engine cylinder is quenched on line in China.
2002, 26(3): 225-228.
Abstract:
The weldability,appearance of weld and welding deformation of the quenched and tempered 30CrMnSiA with laser beam welding(LBW) are discussed.The metallographic microstructure of the weld area and the performance change of the heat affected zone are analyzed.The welding parameters for penetration larger than 1.5mm for the quenched and tempered 30CrMnSiA with LBW are submitted.The result shows that the satisfactory weld quality of the quenched and tempered 30CrMnSiA with LBW can be obtained easily.The wild crack and the obvious change of performance at the heat affected zone are not decreased by adopting some appropriate welding technique.More study on the mechanism about how the surface nigrescence treatment affects the appearance of the weld is necessary.
The weldability,appearance of weld and welding deformation of the quenched and tempered 30CrMnSiA with laser beam welding(LBW) are discussed.The metallographic microstructure of the weld area and the performance change of the heat affected zone are analyzed.The welding parameters for penetration larger than 1.5mm for the quenched and tempered 30CrMnSiA with LBW are submitted.The result shows that the satisfactory weld quality of the quenched and tempered 30CrMnSiA with LBW can be obtained easily.The wild crack and the obvious change of performance at the heat affected zone are not decreased by adopting some appropriate welding technique.More study on the mechanism about how the surface nigrescence treatment affects the appearance of the weld is necessary.
2002, 26(3): 229-230.
Abstract:
The present status of laser maintainability is not ideal,so an adjust free laser is put forward and maintainability test experiment has been done on the laser.It shows that the mean time to repair reduces form 8.12h to 0.8125h.
The present status of laser maintainability is not ideal,so an adjust free laser is put forward and maintainability test experiment has been done on the laser.It shows that the mean time to repair reduces form 8.12h to 0.8125h.
2002, 26(3): 231-233.
Abstract:
The focusing properties of Gaussian beams passing through two types of spherically aberrated lenses are studied and compared.It is show that the focusing properties depend on the type of the spherically aberrated lenses,the spherical aberration coefficient and Fresnel number.There are different conditions for different spherically aberrated lenses to achieve the focus without focal shift or beyond the geometrical focal point of the lens.
The focusing properties of Gaussian beams passing through two types of spherically aberrated lenses are studied and compared.It is show that the focusing properties depend on the type of the spherically aberrated lenses,the spherical aberration coefficient and Fresnel number.There are different conditions for different spherically aberrated lenses to achieve the focus without focal shift or beyond the geometrical focal point of the lens.
2002, 26(3): 234-236.
Abstract:
Based on Collinsinteg ralformula,the propagation of cosine Gaussian beams passing through a first order paraxial optical system with rectangular aperture is studied.With the rectangular function converted to a sum of complex Gaussian functions,a closed for m propagation expression for Gaussian beams is derived.Take a thin lens system with hard edge aperture as an example,numerical calculation is performed.The computation result conforms to that obtained by the straightforward integration of Collins formula.The principal advantage of the method is the great reduction of computing time.The method can also be applied to the propagation of ot her types of laser beams passing an optical system with a hard edge aperture.
Based on Collinsinteg ralformula,the propagation of cosine Gaussian beams passing through a first order paraxial optical system with rectangular aperture is studied.With the rectangular function converted to a sum of complex Gaussian functions,a closed for m propagation expression for Gaussian beams is derived.Take a thin lens system with hard edge aperture as an example,numerical calculation is performed.The computation result conforms to that obtained by the straightforward integration of Collins formula.The principal advantage of the method is the great reduction of computing time.The method can also be applied to the propagation of ot her types of laser beams passing an optical system with a hard edge aperture.
2002, 26(3): 237-240.
Abstract:
The article introduces the application of DSPI in displacement,deformation,vibration and medicine diagnose and the development at home and abroad. A new application of DSPI in speech recognition is analyzed and discussed in detail.
The article introduces the application of DSPI in displacement,deformation,vibration and medicine diagnose and the development at home and abroad. A new application of DSPI in speech recognition is analyzed and discussed in detail.
