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RSS2005 Vol. 29, No. 2
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2005, 29(2): 113-115,137.
[Abstract]
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Abstract:
The laser-alloyed layer is fabricated on the surface of puretitanium with graphite powder.The microstructures and phase constituents of the alloyed layers are investigated by means of SEM,EPMA,XRD and HRTEM.The results show that a great deal of dendritic TiC crystals are formed in the alloyed layer.The growth mechanism of dendritic TiC crystals is theoretically analyzed,at first they continuously grow into dentritic TiC embryo crystals and then each of them acts as many nucleuses on which the lateral growths begin.So the final morphologies of dendritic TiC crystals look as if they were composed of crystallitic grains in a linear arrangement.The test results show that the hardness of the alloyed layers is much higher than that of the matrix and the wear coe fficient of alloyed layers is significantly lower than that of the substrate.Changing laser processing parameters can greatly affect the microstructures and mechanical properties of the alloyed layers,ideal alloyed surface can be achieved only if optimum parameters selected.
The laser-alloyed layer is fabricated on the surface of puretitanium with graphite powder.The microstructures and phase constituents of the alloyed layers are investigated by means of SEM,EPMA,XRD and HRTEM.The results show that a great deal of dendritic TiC crystals are formed in the alloyed layer.The growth mechanism of dendritic TiC crystals is theoretically analyzed,at first they continuously grow into dentritic TiC embryo crystals and then each of them acts as many nucleuses on which the lateral growths begin.So the final morphologies of dendritic TiC crystals look as if they were composed of crystallitic grains in a linear arrangement.The test results show that the hardness of the alloyed layers is much higher than that of the matrix and the wear coe fficient of alloyed layers is significantly lower than that of the substrate.Changing laser processing parameters can greatly affect the microstructures and mechanical properties of the alloyed layers,ideal alloyed surface can be achieved only if optimum parameters selected.
2005, 29(2): 116-118.
Abstract:
A single objective lens with numerical aperture of 0.85 is designed as the coral component of the super high-density optical disk system,which is done with three tools respectively,i.e.two business optical design softwares Zemax and CodeV and the latest CEDDA(characteristic equations discretely defined aspherics)method.The design adopts the latest form of the single bi-aspherical lens in the world with the consideration of decenter error in the manafacture,field error in the application and a reasonable structure in practical application.So that the objective lens has a RMS wavefront error less than 1/30λ and meets the technical requivement.
A single objective lens with numerical aperture of 0.85 is designed as the coral component of the super high-density optical disk system,which is done with three tools respectively,i.e.two business optical design softwares Zemax and CodeV and the latest CEDDA(characteristic equations discretely defined aspherics)method.The design adopts the latest form of the single bi-aspherical lens in the world with the consideration of decenter error in the manafacture,field error in the application and a reasonable structure in practical application.So that the objective lens has a RMS wavefront error less than 1/30λ and meets the technical requivement.
2005, 29(2): 119-122,152.
Abstract:
A review about application of SBS phase conjugation technique in laser MOPA system is given.Several typical experimental schemes for aberration correction,depolarization compensation,laser beam combination are introduced and possible future research directions are indicated.
A review about application of SBS phase conjugation technique in laser MOPA system is given.Several typical experimental schemes for aberration correction,depolarization compensation,laser beam combination are introduced and possible future research directions are indicated.
2005, 29(2): 123-125,134.
Abstract:
A new technology to prepare thick film resistors directly by laser micro-cladding resistor pastes on ceramic substrate is introduced.The preliminary result of the experiment is given.Some line resistors and some special resistors overlapped are fabricated successfully.Also the mechanisms of resistors formation are analyzed.Mainly the influence of parameters is discussed.The effects of coating thickness, laser power and laser scanning speed on resistor line width are studied in detail.
A new technology to prepare thick film resistors directly by laser micro-cladding resistor pastes on ceramic substrate is introduced.The preliminary result of the experiment is given.Some line resistors and some special resistors overlapped are fabricated successfully.Also the mechanisms of resistors formation are analyzed.Mainly the influence of parameters is discussed.The effects of coating thickness, laser power and laser scanning speed on resistor line width are studied in detail.
2005, 29(2): 126-129.
Abstract:
An experiential model of random noise is setup to simulate the ultrafast fluorescence decay for researching how the experiment parameters influence the measurement of time resolved fluorescence spectra.It is found that the SNR can be improved extremely by increasing the gating time and precisi on can be improved by decreasing the delaying time.So the feeble fluorescence signal can be measured and the time resolving degree can be enhanced.The ratio between each decay component's initial intensity varies with different gating time.The relationship between them has been found and the actual value can be deduced from measurement result.The experiment results of GaP testifies our model and the simulation conclusion.This method is successfully used to measure the time resolved fluorescence spectra of LN:Er whose fluorescence is weak.
An experiential model of random noise is setup to simulate the ultrafast fluorescence decay for researching how the experiment parameters influence the measurement of time resolved fluorescence spectra.It is found that the SNR can be improved extremely by increasing the gating time and precisi on can be improved by decreasing the delaying time.So the feeble fluorescence signal can be measured and the time resolving degree can be enhanced.The ratio between each decay component's initial intensity varies with different gating time.The relationship between them has been found and the actual value can be deduced from measurement result.The experiment results of GaP testifies our model and the simulation conclusion.This method is successfully used to measure the time resolved fluorescence spectra of LN:Er whose fluorescence is weak.
2005, 29(2): 130-131,168.
Abstract:
A miniLD laser rangefinder is introduced.The construction, operation principle and key technology of the system are discussed.This system has the characteristics of simple construction and low cost.It can be used in all kinds of intelligent vehicles as an anti-collision radar and other situ ations where high precision is not needed.
A miniLD laser rangefinder is introduced.The construction, operation principle and key technology of the system are discussed.This system has the characteristics of simple construction and low cost.It can be used in all kinds of intelligent vehicles as an anti-collision radar and other situ ations where high precision is not needed.
2005, 29(2): 132-134.
Abstract:
The experiments of micro-machining metal and semiconductor pieces by 248nm KrF excimer laser directetching are carried out.Transverse affect zone is observed on the machined samples'surface.It includes two regions which are described by their dimension and color.The relationship between the regions and the parameters of the laser are studied.The measures to reduce the transverse affect zone are also provided based on the results of the experi ments.
The experiments of micro-machining metal and semiconductor pieces by 248nm KrF excimer laser directetching are carried out.Transverse affect zone is observed on the machined samples'surface.It includes two regions which are described by their dimension and color.The relationship between the regions and the parameters of the laser are studied.The measures to reduce the transverse affect zone are also provided based on the results of the experi ments.
2005, 29(2): 135-137.
Abstract:
The 1.1mm thin disk is pumped by CW 800W high power diode lasers stack.The fast axis of each diode laser is collimated with an aspheric microlens.Two macroscopic lenses are used to focus the light by transforming the fast axis and the slow axis,and a 10mm×7mm spot is achieved in the surface of the thin disk.The pumping light that is not absorbed by the thin disk passes the thin disk again when reflected by the spherical reflector,and high absorbing efficiency is obtained.Up to 800W can be focused on a 10mm×7mm spot with the beam parameter product of 640mm·mrad and 540mm·mrad in the fast and slow axis.The pumping light tested by the CCD camera is nearly the symmetric beam.Its cou pling efficiency is up to 80.5% in the 10mm×7mm spot with the aspheric microlens and two cylinder lenses.
The 1.1mm thin disk is pumped by CW 800W high power diode lasers stack.The fast axis of each diode laser is collimated with an aspheric microlens.Two macroscopic lenses are used to focus the light by transforming the fast axis and the slow axis,and a 10mm×7mm spot is achieved in the surface of the thin disk.The pumping light that is not absorbed by the thin disk passes the thin disk again when reflected by the spherical reflector,and high absorbing efficiency is obtained.Up to 800W can be focused on a 10mm×7mm spot with the beam parameter product of 640mm·mrad and 540mm·mrad in the fast and slow axis.The pumping light tested by the CCD camera is nearly the symmetric beam.Its cou pling efficiency is up to 80.5% in the 10mm×7mm spot with the aspheric microlens and two cylinder lenses.
2005, 29(2): 138-141.
Abstract:
Using excimer laser to manufacture polymer materials can get more ideal biochips.Considering the needed performances of materials used in fabrication of biochips,PMMA and PC's properties are compared.These properties involve in the transmittance of light waves of different wavelengths.The micro-structure of polymer materials after micromachined by excimer laser,the correlation of the ablation depth per pulse with different fluences of excimer laser for different polymers is measured.The energy of KrF excimer laser can be totally absorbed by PMMA and PC,therefore micromachining of biochip can be done by using excimer laser on PMMA and PC's surfaces.The influence on detection quality of PMMA is smaller than PC.The ablation depth per pulse of PMMA to excim er laser is higher than PC under the same fluence.PMMA is manufactured more easily but the quality of micro-structure ablated is worse than PC because of different reaction mechanics to excimer laser.
Using excimer laser to manufacture polymer materials can get more ideal biochips.Considering the needed performances of materials used in fabrication of biochips,PMMA and PC's properties are compared.These properties involve in the transmittance of light waves of different wavelengths.The micro-structure of polymer materials after micromachined by excimer laser,the correlation of the ablation depth per pulse with different fluences of excimer laser for different polymers is measured.The energy of KrF excimer laser can be totally absorbed by PMMA and PC,therefore micromachining of biochip can be done by using excimer laser on PMMA and PC's surfaces.The influence on detection quality of PMMA is smaller than PC.The ablation depth per pulse of PMMA to excim er laser is higher than PC under the same fluence.PMMA is manufactured more easily but the quality of micro-structure ablated is worse than PC because of different reaction mechanics to excimer laser.
2005, 29(2): 142-144,204.
Abstract:
In order to adapt to market competition needs of rapid product update of the modern manufacture and to achieve sheet metal production rapid,effective and low-cost requirements,according to the theory and characteristic of the creation of laser concussion,a new arithmetic based on the slicing technology of STL model was brought forward to achieve the auto-generation of laser head movementtrace in laser concussion.This technology can solve the problem of continuous process dusing laser concussion.The emulational result shows that the figuration dimensions of the cracked sheet metal basically satisfy requirements.This method is still in the phases of research and development.
In order to adapt to market competition needs of rapid product update of the modern manufacture and to achieve sheet metal production rapid,effective and low-cost requirements,according to the theory and characteristic of the creation of laser concussion,a new arithmetic based on the slicing technology of STL model was brought forward to achieve the auto-generation of laser head movementtrace in laser concussion.This technology can solve the problem of continuous process dusing laser concussion.The emulational result shows that the figuration dimensions of the cracked sheet metal basically satisfy requirements.This method is still in the phases of research and development.
2005, 29(2): 145-147.
Abstract:
Amino acid is of virtual significance to investigate t he diffusion behavior of amino acid in aqueous solution.Real-time holographic i nterferometer is employed to study the diffusion of glycine,alanine,valine aci d at 298.15K,and diffusion coefficients under 5 various concentrations are meas ured respectively.In addition,the experimental results and affecting factors a re analyzed and discussed.This investigation provides a fundament to profoundly study the diffusion and mass transfer mechanism of amino acid in aqueous soluti on.
Amino acid is of virtual significance to investigate t he diffusion behavior of amino acid in aqueous solution.Real-time holographic i nterferometer is employed to study the diffusion of glycine,alanine,valine aci d at 298.15K,and diffusion coefficients under 5 various concentrations are meas ured respectively.In addition,the experimental results and affecting factors a re analyzed and discussed.This investigation provides a fundament to profoundly study the diffusion and mass transfer mechanism of amino acid in aqueous soluti on.
2005, 29(2): 148-149,164.
Abstract:
Treating radiation-induced absorption as superposition of process of excitation and response, a new model is proposed to describe the radiation-induced absorption in optical fibers in space environment using the data obtained in the ground-based laboratory.There are two kinds of most important radiation in space environment: background radiation which is stable and low radiation rate and solar flare which is paroxysmal and high radiation rate.Considering the different characteristics of background radiation and solar flare, the exciting function is treated in different ways, resulting in different models.Synthesizing the different models, a new theory is obta ined out to describe the loss of optical fiber in space environment.
Treating radiation-induced absorption as superposition of process of excitation and response, a new model is proposed to describe the radiation-induced absorption in optical fibers in space environment using the data obtained in the ground-based laboratory.There are two kinds of most important radiation in space environment: background radiation which is stable and low radiation rate and solar flare which is paroxysmal and high radiation rate.Considering the different characteristics of background radiation and solar flare, the exciting function is treated in different ways, resulting in different models.Synthesizing the different models, a new theory is obta ined out to describe the loss of optical fiber in space environment.
2005, 29(2): 150-152.
Abstract:
A novel wavelength detection scheme is demonstrated for measuring the wavelength of fiber grating sensors.A new cascaded structure is used in the experimental system mu ltiplex fiber grating tunable filters.The peak wavelength of sensing signal in scanning mode is analyzed.The calibration technique is adopted by the reference wavelength,which eliminates the error induced by wavelength creepage when the filters are tuned.The results show that the detection range reaches 23nm,the wave length resolution is 3.1pm,and the strain resolution is 2.56με.
A novel wavelength detection scheme is demonstrated for measuring the wavelength of fiber grating sensors.A new cascaded structure is used in the experimental system mu ltiplex fiber grating tunable filters.The peak wavelength of sensing signal in scanning mode is analyzed.The calibration technique is adopted by the reference wavelength,which eliminates the error induced by wavelength creepage when the filters are tuned.The results show that the detection range reaches 23nm,the wave length resolution is 3.1pm,and the strain resolution is 2.56με.
2005, 29(2): 153-155,161.
Abstract:
In order to improve the blocking performance of OBS, FDL buffer queuing and scheduling on OBS with fixed length scheme is disscused and based on the intermediate shared FDL buffer architecture the longest queue priority schedule scheme is put forward.Smulation showes that the FDL buffer can be shared by all output ports with a better blocking performance and utilization.
In order to improve the blocking performance of OBS, FDL buffer queuing and scheduling on OBS with fixed length scheme is disscused and based on the intermediate shared FDL buffer architecture the longest queue priority schedule scheme is put forward.Smulation showes that the FDL buffer can be shared by all output ports with a better blocking performance and utilization.
2005, 29(2): 156-158.
Abstract:
Based on the principle of grating diffraction, by using television measuring system to measure the offset between the imaging of incident laser and the optical axis to confirm the angle of incidence and the angle of diffraction of the grating, a method of measuring incident laser wavelength in far field with grating is brought up.The measurement principle and the optical system of this method are introduced.The expressions of calculating laser wavel ength are educed in detail.The expressions of calculating the precision of wavel ength measurement are presented,after analyzing the structure of measurement system.The feasibility of this method is testified by the simulation experiment of far field measurement.
Based on the principle of grating diffraction, by using television measuring system to measure the offset between the imaging of incident laser and the optical axis to confirm the angle of incidence and the angle of diffraction of the grating, a method of measuring incident laser wavelength in far field with grating is brought up.The measurement principle and the optical system of this method are introduced.The expressions of calculating laser wavel ength are educed in detail.The expressions of calculating the precision of wavel ength measurement are presented,after analyzing the structure of measurement system.The feasibility of this method is testified by the simulation experiment of far field measurement.
2005, 29(2): 159-161.
Abstract:
A stress sensitivity enhancement model of optical fiber Bragg gratings is proposed.The relationships between stress and relative shift of center wavelength and the expression of stress sensitivity coefficient of the enhanced fiber Bragg gratings are derived.The elastic modulus of the model is also put forward.It is pointed out that the stress sensitivity coefficient of fiber Bragg gratings can be enhanced by properly selecting the elastic modulus and the size of the elastic part.
A stress sensitivity enhancement model of optical fiber Bragg gratings is proposed.The relationships between stress and relative shift of center wavelength and the expression of stress sensitivity coefficient of the enhanced fiber Bragg gratings are derived.The elastic modulus of the model is also put forward.It is pointed out that the stress sensitivity coefficient of fiber Bragg gratings can be enhanced by properly selecting the elastic modulus and the size of the elastic part.
2005, 29(2): 162-164.
Abstract:
Er3+ doped niobate-tellurite glasses(EDTNb) are prepared, whose host compositions are TeO2,Nb2O5,ZnO and Na2O.The di fferential thermal analysis (DTA) curves of the glasses show that the thermal stability of EDTNb glasses against crystallization increases due to the introducti on of 4% Nb2O5.The measured absorption spectra are analyzed by McCumber theo ries in order to obtain the spectroscopic properties of the glasses.It is found that the peak stimulated emission crosssection of EDTNb glasses is 8.9×10-21cm2, which is 8% larger than that of tellurite glasses.
Er3+ doped niobate-tellurite glasses(EDTNb) are prepared, whose host compositions are TeO2,Nb2O5,ZnO and Na2O.The di fferential thermal analysis (DTA) curves of the glasses show that the thermal stability of EDTNb glasses against crystallization increases due to the introducti on of 4% Nb2O5.The measured absorption spectra are analyzed by McCumber theo ries in order to obtain the spectroscopic properties of the glasses.It is found that the peak stimulated emission crosssection of EDTNb glasses is 8.9×10-21cm2, which is 8% larger than that of tellurite glasses.
2005, 29(2): 165-168.
Abstract:
A new method,transmission spectrum method combined the normal simplex algorithm,is proposed to measure the grating parameters.Firstly,the transmission spectrum of the range from 200nm~900nm is obtained according to a certain grating model with the Fourier model method and reflection and tran smission coefficient matrix method (RTCM),based on which the Gaussian noises with different standard deviations are added to it to get the simulated measuring value of transmission spectrum,then five points are gotten respectively from the transmission spectrum with or without Gaussian noises.Secondly,the original supposed value of grating parameters is brought to the estimating function.Through repeatedly computing with the normal simplex algorithm,the grating parameters are obtained.
A new method,transmission spectrum method combined the normal simplex algorithm,is proposed to measure the grating parameters.Firstly,the transmission spectrum of the range from 200nm~900nm is obtained according to a certain grating model with the Fourier model method and reflection and tran smission coefficient matrix method (RTCM),based on which the Gaussian noises with different standard deviations are added to it to get the simulated measuring value of transmission spectrum,then five points are gotten respectively from the transmission spectrum with or without Gaussian noises.Secondly,the original supposed value of grating parameters is brought to the estimating function.Through repeatedly computing with the normal simplex algorithm,the grating parameters are obtained.
2005, 29(2): 169-171,182.
Abstract:
Based on geometric theory,diffractive optical elements applied to shape laser beams is designed,the phase expression of the diffractive optical elements is deduced.As an example,DOE shaping input Gaussian beam into the square frame shape is designed.The calculation results are satisfactory by means of computer simulation.At the same time,experimental results prove the property of the design method,theoretical deduction and program design and the a ccuracy of the design method.
Based on geometric theory,diffractive optical elements applied to shape laser beams is designed,the phase expression of the diffractive optical elements is deduced.As an example,DOE shaping input Gaussian beam into the square frame shape is designed.The calculation results are satisfactory by means of computer simulation.At the same time,experimental results prove the property of the design method,theoretical deduction and program design and the a ccuracy of the design method.
2005, 29(2): 172-175,179.
Abstract:
The analytical expressions of reflectance and penetration depth of a light beam transmitted in the back-side-coated chirped mirror are obtained through couple-mode equations with boundary conditions.The results hows that it is more integrated and precise in calculating and analyzing the light's transmission rule in the BASIC mirror after taking boundary conditions into consideration.
The analytical expressions of reflectance and penetration depth of a light beam transmitted in the back-side-coated chirped mirror are obtained through couple-mode equations with boundary conditions.The results hows that it is more integrated and precise in calculating and analyzing the light's transmission rule in the BASIC mirror after taking boundary conditions into consideration.
2005, 29(2): 176-179.
Abstract:
The development of laser Doppler technique in vibration measurement is presented with emphasis on latest methods.
The development of laser Doppler technique in vibration measurement is presented with emphasis on latest methods.
2005, 29(2): 180-182.
Abstract:
The constraints between two units are analyzed.Based on the results and fractional correlation theory,a new scale distortion invariant pattern recongnition method is proposed.Simulation results show that when a scale distortion inputimage can't berightly recognized by the conventional correlation,it can be recognized well with the method.
The constraints between two units are analyzed.Based on the results and fractional correlation theory,a new scale distortion invariant pattern recongnition method is proposed.Simulation results show that when a scale distortion inputimage can't berightly recognized by the conventional correlation,it can be recognized well with the method.
2005, 29(2): 183-186.
Abstract:
The main metal powders of selective laser sintering (SLS) are introduced.The demands and principles of material choice and design of SLS are pointed out.Metal powders must fit with SLS technology in the aspect of forming precision,speed,strength and cost.The development tendency of metal powders is put forward.
The main metal powders of selective laser sintering (SLS) are introduced.The demands and principles of material choice and design of SLS are pointed out.Metal powders must fit with SLS technology in the aspect of forming precision,speed,strength and cost.The development tendency of metal powders is put forward.
2005, 29(2): 187-189,193.
Abstract:
In order to improve the output stability of LD pumpe d Nd:YAG laser Q-switched by Cr4+:YAG,the directional prism resonator is used,a single smooth laser pulse has been achieved with the energy stability changing from 7.3%~2.2%,pulse-width stability changing from 13.5%~6.5%,repetition rate stability changing from 0.01%~0.005%.The experimental result shows that compared with the plano-plane resonator,the directional prism resonator improves output stability of the laser greatly.It is reported for the first time that the directional prism resonator can eliminate the tail-pulse.
In order to improve the output stability of LD pumpe d Nd:YAG laser Q-switched by Cr4+:YAG,the directional prism resonator is used,a single smooth laser pulse has been achieved with the energy stability changing from 7.3%~2.2%,pulse-width stability changing from 13.5%~6.5%,repetition rate stability changing from 0.01%~0.005%.The experimental result shows that compared with the plano-plane resonator,the directional prism resonator improves output stability of the laser greatly.It is reported for the first time that the directional prism resonator can eliminate the tail-pulse.
2005, 29(2): 190-193.
Abstract:
Using the linearized nonlinear Schrödinger equation obtained with the aid of the small signal approximation,analytical expressions for the amplitude and phase of a perturbation propagating in anoptical fiber have been deduced.The evolution characteristics of the amplitude and phase of the perturbation has been calculated and discussed.The moving trajectories portrayed by the perturbation phasors have been obtained under the polar coordinates.The characteristics and the asymptotic behaviors of the trajectories have been analyzed.The results show that the evolution of the perturbation is intensively influenced by the initial perturbation phase.
Using the linearized nonlinear Schrödinger equation obtained with the aid of the small signal approximation,analytical expressions for the amplitude and phase of a perturbation propagating in anoptical fiber have been deduced.The evolution characteristics of the amplitude and phase of the perturbation has been calculated and discussed.The moving trajectories portrayed by the perturbation phasors have been obtained under the polar coordinates.The characteristics and the asymptotic behaviors of the trajectories have been analyzed.The results show that the evolution of the perturbation is intensively influenced by the initial perturbation phase.
2005, 29(2): 194-195,224.
Abstract:
In an optical system,"cat eye effect" can be modeled as a focal lens system.Based on the model,with the property that it can reflect the input laser exactly back along the direction the laser incides,a "cat eye" system can be applied as an equivalent laser resonant mirror to achieve the laser resonance.At the same time,the equivalent reflectivity of the "cat eye" system has been calculated.The experimental results have also proved this point of view.The laser resonance has been obtained with deferent mediums at the focal plane of our simulated "cat eye" system and all these mediums have been destroyed by the focal laser spots.
In an optical system,"cat eye effect" can be modeled as a focal lens system.Based on the model,with the property that it can reflect the input laser exactly back along the direction the laser incides,a "cat eye" system can be applied as an equivalent laser resonant mirror to achieve the laser resonance.At the same time,the equivalent reflectivity of the "cat eye" system has been calculated.The experimental results have also proved this point of view.The laser resonance has been obtained with deferent mediums at the focal plane of our simulated "cat eye" system and all these mediums have been destroyed by the focal laser spots.
2005, 29(2): 196-198.
Abstract:
Methods used to distinguish quickly between semiconducting and metallic single-walled carbon nanotubes(SWNTs) are introduced,whose luminescence mechanism and new applications are summarized.Our numerical calculation results are consistent with whose of the previous experiments.
Methods used to distinguish quickly between semiconducting and metallic single-walled carbon nanotubes(SWNTs) are introduced,whose luminescence mechanism and new applications are summarized.Our numerical calculation results are consistent with whose of the previous experiments.
2005, 29(2): 199-200.
Abstract:
The mathematical relationship of breakdown voltage of gas discharge in CO2 laser excited by RF is derived by using reduced model based on the theory of gas discharge and several physical parameters which influence gas discharge breakdown of laser are pointed out.By means of the experiment,the relationship between the power infused and the frequency which cause the gas discharge breakdown is drawn.Compared the relative experimental test results with theoretical conclusion,both are consistent.
The mathematical relationship of breakdown voltage of gas discharge in CO2 laser excited by RF is derived by using reduced model based on the theory of gas discharge and several physical parameters which influence gas discharge breakdown of laser are pointed out.By means of the experiment,the relationship between the power infused and the frequency which cause the gas discharge breakdown is drawn.Compared the relative experimental test results with theoretical conclusion,both are consistent.
2005, 29(2): 201-204.
Abstract:
The pure titanium was nitrided by laser nitriding method in atmospheric ambient with the radiation of CW CO2 laser.The activated nitrogen beam was introduced into the melting pool together with the laser beam.The samples were tested with X-ray diffraction(XRD) method.The results show that the nitridation on the surface of titanium can be realized by choosing proper laser parameters,including laser power density,scanning speed and pre-heated treat ment to nitrogen gas.The minimum power density is 6.5×105W·cm-2 and the maximum scanning speed is 600mm·min-1.The distribution of temperatu refield during the nitriding process is simulated with semi-infinity model.From this model,the theoretical threshold of scanning speed is deduced to be 600mm ·min-1.This value is near to the experimental result.
The pure titanium was nitrided by laser nitriding method in atmospheric ambient with the radiation of CW CO2 laser.The activated nitrogen beam was introduced into the melting pool together with the laser beam.The samples were tested with X-ray diffraction(XRD) method.The results show that the nitridation on the surface of titanium can be realized by choosing proper laser parameters,including laser power density,scanning speed and pre-heated treat ment to nitrogen gas.The minimum power density is 6.5×105W·cm-2 and the maximum scanning speed is 600mm·min-1.The distribution of temperatu refield during the nitriding process is simulated with semi-infinity model.From this model,the theoretical threshold of scanning speed is deduced to be 600mm ·min-1.This value is near to the experimental result.
2005, 29(2): 205-206,218.
Abstract:
The light back-scattering property has been developed primarily.The results show that the property of water has been changed obviously because of the influence of bubbles.The intensity of light back scattered from bubbles is related to the type of detector,the distance and the density of bub bles.The light signal back-scattered from wake bubbles can be detected by taking some measures.
The light back-scattering property has been developed primarily.The results show that the property of water has been changed obviously because of the influence of bubbles.The intensity of light back scattered from bubbles is related to the type of detector,the distance and the density of bub bles.The light signal back-scattered from wake bubbles can be detected by taking some measures.
2005, 29(2): 207-209,212.
Abstract:
Limited by characteristic discharging structure and oscillating cavity,the beam energy profile of the excimer laser appears asymmetrically.The principles of various types of beam homogenizer,as well as specifications scaling the beam uniformity are presented.The pro-and-cons of these different technologies and their different valid applications are also discussed.
Limited by characteristic discharging structure and oscillating cavity,the beam energy profile of the excimer laser appears asymmetrically.The principles of various types of beam homogenizer,as well as specifications scaling the beam uniformity are presented.The pro-and-cons of these different technologies and their different valid applications are also discussed.
2005, 29(2): 210-212.
Abstract:
In order to discuss the application of laser active jam technology for laser chaff,a numerical calculating method of light scattering section with the tool of MATLAB software is presented.The influence of polarization characteristic of the incidence light on the light scattering section is a nalyzed.The conclusion that the degree of polarization should be taken into cons ideration in laser active jam has been drawn.
In order to discuss the application of laser active jam technology for laser chaff,a numerical calculating method of light scattering section with the tool of MATLAB software is presented.The influence of polarization characteristic of the incidence light on the light scattering section is a nalyzed.The conclusion that the degree of polarization should be taken into cons ideration in laser active jam has been drawn.
2005, 29(2): 213-215,221.
Abstract:
Using two-dimension finite-difference time-domain (2D-FDTD) method,the optical fields of solid immersion lens are studied when ill uminated by linear polarized focusing Gaussian beam.The simulated results reveal that the portrait optical field is produced,which broadenes the emitted beamradius.The beam of the component field whose polarization is parallel to the incid ent beam is smaller than that of the total optical field and the higher the refractive index is,the larger the contrast is.
Using two-dimension finite-difference time-domain (2D-FDTD) method,the optical fields of solid immersion lens are studied when ill uminated by linear polarized focusing Gaussian beam.The simulated results reveal that the portrait optical field is produced,which broadenes the emitted beamradius.The beam of the component field whose polarization is parallel to the incid ent beam is smaller than that of the total optical field and the higher the refractive index is,the larger the contrast is.
2005, 29(2): 216-218.
Abstract:
As the key apparatus in ASON(automatic switched optical networks),all optical wavelength conversion device plays a very important role.A theoretical model of wavelength conversion based on semiconductor laser is established.Using rate equation,the characteristics of wavelength conversion are analyzed based on numerical solution of theoretical model.A set of experimental equipment using fiber Bragg grating external cavity semiconductor laser foral loptical wavelength conversion are accomplished by ourselves,experimental result are discussed synchronously.The result of experiment is accordant with theoretical analysis.Research indicates that it is applied key to reduce photon life and optimize the structure of external cavity in future intelligent optical network.
As the key apparatus in ASON(automatic switched optical networks),all optical wavelength conversion device plays a very important role.A theoretical model of wavelength conversion based on semiconductor laser is established.Using rate equation,the characteristics of wavelength conversion are analyzed based on numerical solution of theoretical model.A set of experimental equipment using fiber Bragg grating external cavity semiconductor laser foral loptical wavelength conversion are accomplished by ourselves,experimental result are discussed synchronously.The result of experiment is accordant with theoretical analysis.Research indicates that it is applied key to reduce photon life and optimize the structure of external cavity in future intelligent optical network.
2005, 29(2): 219-221.
Abstract:
In order to studty the spectral character of the calcite/BaF2 UV polarizing prism beam deviation angle,the mathematical software Origin7.0 is analyzed and two means are designed to modify the beam deviation angle.
In order to studty the spectral character of the calcite/BaF2 UV polarizing prism beam deviation angle,the mathematical software Origin7.0 is analyzed and two means are designed to modify the beam deviation angle.
2005, 29(2): 222-224.
Abstract:
Measurement of monochrome local length (MLL) of alens based on define of fractional Fourier transform is generalized and discussed.A new experimental design for testing MLL of lens by a single slitis studied,and then the experimental device and program flow chart of this method are put for ward.This method is flexible and easy to realize self-acting test.
Measurement of monochrome local length (MLL) of alens based on define of fractional Fourier transform is generalized and discussed.A new experimental design for testing MLL of lens by a single slitis studied,and then the experimental device and program flow chart of this method are put for ward.This method is flexible and easy to realize self-acting test.
