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RSS2004 Vol. 28, No. 3
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2004, 28(3): 225-227.
[Abstract]
[PDF 710KB]
Abstract:
A laser controller consisting of MCS-51 microcontroller and Texas Instruments DRV592 power driver is presented.The DRV592 is a high-efficiency,high-current H-bridge ideal for driving a wide variety of the thermoelectric cooler(TEC)elements in systems powered from2.8Vto5.5V.The MCS-51 microcontroller implements a digital proportional-integral-derivative feedback controller using an analog-to-digital converter to read the thermistor,and direct output of pulse-width-modulated waveforms to the H-bridge DRV592 power amplifier.The laser controller can achieve ±0.1℃ temperature and milliampere accuracy,which is internally protected against thermal and current overloads.
A laser controller consisting of MCS-51 microcontroller and Texas Instruments DRV592 power driver is presented.The DRV592 is a high-efficiency,high-current H-bridge ideal for driving a wide variety of the thermoelectric cooler(TEC)elements in systems powered from2.8Vto5.5V.The MCS-51 microcontroller implements a digital proportional-integral-derivative feedback controller using an analog-to-digital converter to read the thermistor,and direct output of pulse-width-modulated waveforms to the H-bridge DRV592 power amplifier.The laser controller can achieve ±0.1℃ temperature and milliampere accuracy,which is internally protected against thermal and current overloads.
2004, 28(3): 228-230,254.
Abstract:
This paper introduces the theory of laser diode(LD)accelerating lifetime testing and mathematic model of life testing,based on wihich a new type of LDs burn-in & automatic life testing system was developed.It continuously samples the power of LDs which works under automatic current control and under the airproof condition filled with nitrogen at testing temperature,plots power-time curve of LD and deduces the working life of LD.
This paper introduces the theory of laser diode(LD)accelerating lifetime testing and mathematic model of life testing,based on wihich a new type of LDs burn-in & automatic life testing system was developed.It continuously samples the power of LDs which works under automatic current control and under the airproof condition filled with nitrogen at testing temperature,plots power-time curve of LD and deduces the working life of LD.
2004, 28(3): 231-233,236.
Abstract:
In order to study the metrical precision of reflectivity via cavity ring-down spectroscopy,first of all,it is investigated that influence of length misadjustment of ring-down cavity on its mode coupling.Then,based on propagation of Gaussian beam,it is deduced that relation between detector's aperture and output power of ring-down cavity of length misadjustment,and it is also numerically simulated that influence of detector's aperture on metrical precision.Results show that the bigger the detector's aperture is,the lower the metrical relative error is.
In order to study the metrical precision of reflectivity via cavity ring-down spectroscopy,first of all,it is investigated that influence of length misadjustment of ring-down cavity on its mode coupling.Then,based on propagation of Gaussian beam,it is deduced that relation between detector's aperture and output power of ring-down cavity of length misadjustment,and it is also numerically simulated that influence of detector's aperture on metrical precision.Results show that the bigger the detector's aperture is,the lower the metrical relative error is.
2004, 28(3): 234-236.
Abstract:
We receive the laser pulse signal with the binary photo-electric detector,deal the signal with the circuit designed on the basis of correlation detection to improve SNR.The experimental results show that improved SNR can reach 26dB while the signal submerged in noise is processed by the circuit,and it can satisfy the application requirement under most circumstance.
We receive the laser pulse signal with the binary photo-electric detector,deal the signal with the circuit designed on the basis of correlation detection to improve SNR.The experimental results show that improved SNR can reach 26dB while the signal submerged in noise is processed by the circuit,and it can satisfy the application requirement under most circumstance.
2004, 28(3): 237-240,270.
Abstract:
316L stainless steel powders were clad onto AISI 1045 steel substrate using laser multi-track overlapping process.The microstructure and anodic polarization corrosion behavior in 2mol NaCl,1mol FeCl3 and 0.5mol HCl aqueous solutions of the clad layer and its commercial counterpart bulk 316L stainless steel were comparatively investigated.The chemical composition of the clad layer resulted from dilution from the substrate is quite different from that of the original 316L stainless steel powders,the final microstructure of the clad layer comprised predominant martensite and very small amount of residual austenite.The anodic polarization behavior of the clad layer was similar to that of its commercial counterpart bulk in the aqueous solutions mentioned above.There exists Tafel relationship between the superpotential of anodic and cathodic polarization and current for both the clad layer and the bulk.The clad layer displays good passive performance and pitting corrosion resistance.Compared with the bulk,however,the clad layer has larger self-corrosive current density,lower potential and smaller polarization resistance,and its corrosion resistance slightly degrades.
316L stainless steel powders were clad onto AISI 1045 steel substrate using laser multi-track overlapping process.The microstructure and anodic polarization corrosion behavior in 2mol NaCl,1mol FeCl3 and 0.5mol HCl aqueous solutions of the clad layer and its commercial counterpart bulk 316L stainless steel were comparatively investigated.The chemical composition of the clad layer resulted from dilution from the substrate is quite different from that of the original 316L stainless steel powders,the final microstructure of the clad layer comprised predominant martensite and very small amount of residual austenite.The anodic polarization behavior of the clad layer was similar to that of its commercial counterpart bulk in the aqueous solutions mentioned above.There exists Tafel relationship between the superpotential of anodic and cathodic polarization and current for both the clad layer and the bulk.The clad layer displays good passive performance and pitting corrosion resistance.Compared with the bulk,however,the clad layer has larger self-corrosive current density,lower potential and smaller polarization resistance,and its corrosion resistance slightly degrades.
2004, 28(3): 241-244.
Abstract:
In order to simplify the structure of the birefringence dual frequency laser in which a birefringence element(a quart crystal or an artificial stress plate)is settled to achieve frequency difference(FD)according to frequency splitting theory,improve the convenience of adjustment,and improve stability of FD,a novel structure of dual frequency laser is constructed,in which the FD is produced by the complex multilayer birefringent film. Different layers of the multilayer film perform different functions for the whole film system of sandwich structure. Utilizing both the transverse Zeeman effect and intra-cavity birefringence effect in a He-Ne laser,about 7.5MHz of FD is achieved in experiments.
In order to simplify the structure of the birefringence dual frequency laser in which a birefringence element(a quart crystal or an artificial stress plate)is settled to achieve frequency difference(FD)according to frequency splitting theory,improve the convenience of adjustment,and improve stability of FD,a novel structure of dual frequency laser is constructed,in which the FD is produced by the complex multilayer birefringent film. Different layers of the multilayer film perform different functions for the whole film system of sandwich structure. Utilizing both the transverse Zeeman effect and intra-cavity birefringence effect in a He-Ne laser,about 7.5MHz of FD is achieved in experiments.
2004, 28(3): 245-247,280.
Abstract:
High voltage wire(HVW)is main obstacle for flying helicopter 60m～200m high.As a cylinder,HVW has special scattering distribution while it is illuminated under laser beams,so the random facet model is employed to analyze the scattering of rough cylinder surfaces.A method is presented to design laser parameters for a helicopter anti-collision radar,which provides theoretical foundation for the design of laser parameter for a helicopter anti-collision laser radar.
High voltage wire(HVW)is main obstacle for flying helicopter 60m～200m high.As a cylinder,HVW has special scattering distribution while it is illuminated under laser beams,so the random facet model is employed to analyze the scattering of rough cylinder surfaces.A method is presented to design laser parameters for a helicopter anti-collision radar,which provides theoretical foundation for the design of laser parameter for a helicopter anti-collision laser radar.
2004, 28(3): 248-250,258.
Abstract:
Based on multimode rate equations,the relaxation oscillation of vertical-cavity surface-emitting lasers(VCSELs)and edge-emitting lasers(EELs)has been studied through SIMULINK provided by MATLAB.The results show that EELs with multiple longitudinal modes have higher relaxation oscillation frequency and shorter turn-on delay time,which are relatively unchanged for VCSELs case.The simulation results also verify the following conclusions:firstly,VCSELs has the merits of single-mode working and high-speed modulation; secondly,the devices with higher bias current or larger spontaneous emission factor exhibit better temporary characteristics;thirdly,the variation rate of VCSELs'side-mode suppression ratio(SMSR)with bias current is higher than that of EELs.Furthermore,the side-mode intensities augment at the same rate with increasing the spontaneous emission factor,and the main-mode intensity decreases accordingly.Controlling this factor effectively can optimize the single-mode characteristic of VCSELs.
Based on multimode rate equations,the relaxation oscillation of vertical-cavity surface-emitting lasers(VCSELs)and edge-emitting lasers(EELs)has been studied through SIMULINK provided by MATLAB.The results show that EELs with multiple longitudinal modes have higher relaxation oscillation frequency and shorter turn-on delay time,which are relatively unchanged for VCSELs case.The simulation results also verify the following conclusions:firstly,VCSELs has the merits of single-mode working and high-speed modulation; secondly,the devices with higher bias current or larger spontaneous emission factor exhibit better temporary characteristics;thirdly,the variation rate of VCSELs'side-mode suppression ratio(SMSR)with bias current is higher than that of EELs.Furthermore,the side-mode intensities augment at the same rate with increasing the spontaneous emission factor,and the main-mode intensity decreases accordingly.Controlling this factor effectively can optimize the single-mode characteristic of VCSELs.
2004, 28(3): 251-254.
Abstract:
By using a beam model with linear non-uniform field profile in the x direction,the effect of beam non-uniformity and nonlinear thermal blooming in the optical beam control system on the far-field characteristics of high-power laser beams is studied.It is found that the non-uniformity of the initial beam affects the focusability and results in the astigmatism.The thermal blooming gives rise to a further decrease of the focusability and a further increase of the astigmatism.In addition,the peak intensity in the far-field is reduced and its position shifts away owing to the thermal blooming.
By using a beam model with linear non-uniform field profile in the x direction,the effect of beam non-uniformity and nonlinear thermal blooming in the optical beam control system on the far-field characteristics of high-power laser beams is studied.It is found that the non-uniformity of the initial beam affects the focusability and results in the astigmatism.The thermal blooming gives rise to a further decrease of the focusability and a further increase of the astigmatism.In addition,the peak intensity in the far-field is reduced and its position shifts away owing to the thermal blooming.
2004, 28(3): 255-258.
Abstract:
The basic theory of the temperature field of optical thin films is given.The temperature field distribution of dielectric thin films irradiated by 10.6μm CO2 lasers has been simulated numerically and analyzed theoretically using alternating direction-implicit technique.Using the Shack-Hartmann wavefront sensor,the thermal distortion of the substrate,the single-layer dielectric thin films with different thickness,and the multi-layer dielectric thin films with different multilayer thin films(YbF3/ZnSe)irradiated by CO2 laser are studied experimentally.It can be shown that the temperature field distribution of thin film coatings irradiated by lasers deperds on the field distribution,power and irradiating time of lasers.For the 10.6μm laser,Ge is the most suitable substrate material.
The basic theory of the temperature field of optical thin films is given.The temperature field distribution of dielectric thin films irradiated by 10.6μm CO2 lasers has been simulated numerically and analyzed theoretically using alternating direction-implicit technique.Using the Shack-Hartmann wavefront sensor,the thermal distortion of the substrate,the single-layer dielectric thin films with different thickness,and the multi-layer dielectric thin films with different multilayer thin films(YbF3/ZnSe)irradiated by CO2 laser are studied experimentally.It can be shown that the temperature field distribution of thin film coatings irradiated by lasers deperds on the field distribution,power and irradiating time of lasers.For the 10.6μm laser,Ge is the most suitable substrate material.
2004, 28(3): 259-261.
Abstract:
Austenitic stainless steel treated with laser clad Ni-based alloy is tested under impact load.There is micro plastic deformation in the base and clad coating.Macro plastic deformation is formed after repeated process,and homogeneous hardening comes into being from clad to base.There is intensive deformation hardening and material-flowing phenomena along the brink of clad coating,on which cracks tend to grow and spread.
Austenitic stainless steel treated with laser clad Ni-based alloy is tested under impact load.There is micro plastic deformation in the base and clad coating.Macro plastic deformation is formed after repeated process,and homogeneous hardening comes into being from clad to base.There is intensive deformation hardening and material-flowing phenomena along the brink of clad coating,on which cracks tend to grow and spread.
2004, 28(3): 262-265.
Abstract:
The reasons of angular non-linearity in 2-D optical scanner are analyzed.Equations of angular of elevation,azimuth and vertical in 2-D scanning are demonstrated.Scanning non-linearity is analyzed.Its influence on angular tracking and scanning imaging is discussed.Method of correction is pointed out.
The reasons of angular non-linearity in 2-D optical scanner are analyzed.Equations of angular of elevation,azimuth and vertical in 2-D scanning are demonstrated.Scanning non-linearity is analyzed.Its influence on angular tracking and scanning imaging is discussed.Method of correction is pointed out.
2004, 28(3): 266-270.
Abstract:
Thermodynamic effects on properties of the polarizing prisms are studied.How the temperature affects the transmissivity and the transmitted intensity disturbance is analytically discussed.The results are in accordance with the experimental ones.The thermodynamic effect on the extinction ratio is studied in the experiment.At last,the destructive experiment has been conducted.It indicates that when the temperature changes too fast,the polarizing prisms will be damaged severely.
Thermodynamic effects on properties of the polarizing prisms are studied.How the temperature affects the transmissivity and the transmitted intensity disturbance is analytically discussed.The results are in accordance with the experimental ones.The thermodynamic effect on the extinction ratio is studied in the experiment.At last,the destructive experiment has been conducted.It indicates that when the temperature changes too fast,the polarizing prisms will be damaged severely.
2004, 28(3): 271-274.
Abstract:
In this paper,the pump limit has been calculated,and the methods that resolve the thermal effect have been summarized.At last,a new method to solve thermal effect has been brought forward.
In this paper,the pump limit has been calculated,and the methods that resolve the thermal effect have been summarized.At last,a new method to solve thermal effect has been brought forward.
2004, 28(3): 275-277.
Abstract:
The termo-optic effect of nematic liquid crystal(LC)(BL-009)is probed by studying the birefringence of LC as the temperature varies.The simple and precise polarized interference method is employed to measure the birefringence of the LC.The transmissivity of the LC is measured as temperature varies from 20℃ to 100℃,the wavelength of the incident light is 630nm,so electric control birefringence of the LC is obtained as temperature varies.After analysing the experimental data,it is found that the law of the falling of electric control birefringence is different when the applied voltage is different.The obtained result is favor of the design and manufacture,application of LC device.
The termo-optic effect of nematic liquid crystal(LC)(BL-009)is probed by studying the birefringence of LC as the temperature varies.The simple and precise polarized interference method is employed to measure the birefringence of the LC.The transmissivity of the LC is measured as temperature varies from 20℃ to 100℃,the wavelength of the incident light is 630nm,so electric control birefringence of the LC is obtained as temperature varies.After analysing the experimental data,it is found that the law of the falling of electric control birefringence is different when the applied voltage is different.The obtained result is favor of the design and manufacture,application of LC device.
2004, 28(3): 278-280.
Abstract:
A method to obtain the azimuth angle of laser is represented,which can avoid complex computation and complex electric circuit.Furthermore,two means to increase the angular resolution including utilizing laser beam intensity ratio and adding more sensors are described,and the relationship between the angular resolution and lens'parameters with different number of sensors is given.Based on this way,higher angular resolution can be obtained with fewer sensors.
A method to obtain the azimuth angle of laser is represented,which can avoid complex computation and complex electric circuit.Furthermore,two means to increase the angular resolution including utilizing laser beam intensity ratio and adding more sensors are described,and the relationship between the angular resolution and lens'parameters with different number of sensors is given.Based on this way,higher angular resolution can be obtained with fewer sensors.
2004, 28(3): 281-285.
Abstract:
The recent development of free-space quantum cryptography is reviewed,which includes free-space quantum cryptography protocols and the process of quantum key distribution. Free-space quantum cryptography is analyzed experimentally.
The recent development of free-space quantum cryptography is reviewed,which includes free-space quantum cryptography protocols and the process of quantum key distribution. Free-space quantum cryptography is analyzed experimentally.
2004, 28(3): 286-288.
Abstract:
Photoelectric saturation is the difficult technical problem in laser simulating system. Pyroelectric detectors depend upon alternating signal,based on which a new kind of laser training system was developed,and the problem of direct light was solved. The structure,basic principle are described. It is proved by experiment that the system is credible and applied.
Photoelectric saturation is the difficult technical problem in laser simulating system. Pyroelectric detectors depend upon alternating signal,based on which a new kind of laser training system was developed,and the problem of direct light was solved. The structure,basic principle are described. It is proved by experiment that the system is credible and applied.
2004, 28(3): 289-292,295.
Abstract:
Based on the propagation law of the second-order moments matrix,the focusing of twisted anisotropic Gaussian-Schell model(AGSM)beams through a lens is studied.Detailed numerical results are presented to illustrate the propagation behavior of focused AGSM beams,including the evolution of beam parameters and the transversal intensity.In particular,the influence of twist term and spatial correlation length on their focusing properties is analyzed.
Based on the propagation law of the second-order moments matrix,the focusing of twisted anisotropic Gaussian-Schell model(AGSM)beams through a lens is studied.Detailed numerical results are presented to illustrate the propagation behavior of focused AGSM beams,including the evolution of beam parameters and the transversal intensity.In particular,the influence of twist term and spatial correlation length on their focusing properties is analyzed.
2004, 28(3): 293-295.
Abstract:
In this paper,the approximate treatment of phase retardation's caculation formula and small-angle incidence when light incidents obliquely in two special sections is given.For the relation between the change of placement and that of retardation is given in theory,we have the theoretical basis to adjust and use correctly phase retarder.
In this paper,the approximate treatment of phase retardation's caculation formula and small-angle incidence when light incidents obliquely in two special sections is given.For the relation between the change of placement and that of retardation is given in theory,we have the theoretical basis to adjust and use correctly phase retarder.
2004, 28(3): 296-297,302.
Abstract:
In the material mechanics,the deflection of metal girder is a minute movement,and can't be measured using the normal regulation.This paper discusses the method of recurrence of the deflection of metal bar by means of holography,and calculates the deflection of metal bar according to the theory of deflection.The computing result is well in accordance with that of the laser holographic experiment,which proves that laser holography is a new intuitional and effective study method for metal material.
In the material mechanics,the deflection of metal girder is a minute movement,and can't be measured using the normal regulation.This paper discusses the method of recurrence of the deflection of metal bar by means of holography,and calculates the deflection of metal bar according to the theory of deflection.The computing result is well in accordance with that of the laser holographic experiment,which proves that laser holography is a new intuitional and effective study method for metal material.
2004, 28(3): 298-302.
Abstract:
The goal of this article is to present a measuring system which is fast and simple to be applied for the middle or large scale production of semiconductor lasers.The simulation is performed to the near field pattern,far field pattern and divergence angle etc.of the semiconductor laser with the finite difference analysis.A measuring system is built to measure the characteristics.Finally,the experimental system error is analyzed,and an approach to cut down the error is presented.Compared with other methods,this measuring system is simple,fast and precise.
The goal of this article is to present a measuring system which is fast and simple to be applied for the middle or large scale production of semiconductor lasers.The simulation is performed to the near field pattern,far field pattern and divergence angle etc.of the semiconductor laser with the finite difference analysis.A measuring system is built to measure the characteristics.Finally,the experimental system error is analyzed,and an approach to cut down the error is presented.Compared with other methods,this measuring system is simple,fast and precise.
2004, 28(3): 303-305,311.
Abstract:
On the basis of high-order mode dispersion analysis,the feasibility of taking use of the high-order mode,which has negative chromatic dispersion,to realize compensation of single mode fiber has been discussed.This paper focuses on study the performance of using LP02 mode as the dispersion compensation of high-order mode and the results indicate that high-order mode dispersion compensation is the high figure of merit scheme.Finally the compensation project of higher order mode based on LP02 mode is designed,moreover the principle of mode transformer is described in detail.
On the basis of high-order mode dispersion analysis,the feasibility of taking use of the high-order mode,which has negative chromatic dispersion,to realize compensation of single mode fiber has been discussed.This paper focuses on study the performance of using LP02 mode as the dispersion compensation of high-order mode and the results indicate that high-order mode dispersion compensation is the high figure of merit scheme.Finally the compensation project of higher order mode based on LP02 mode is designed,moreover the principle of mode transformer is described in detail.
2004, 28(3): 306-308.
Abstract:
The paper describes a CW,non-colling,digital all-solid-stated LD pumped Nd:YVO4 laser driver which adopts microprocessor control,stability power of optics feedback about 10mW output power.The system is composed of stable current source,protection circuit,pulse driver,Si photo-detector amplified and hign-speed microprocessor control system.Based on error variety of nonlinear control curves of LD output laser power by Si photo-detector,we take advantage of window node PID control algorithm to achieve high stability of laser power and reduce error amends.Combining appropriate hardware and software in our driver,we have achieved a variety of protection features including the ability to match and harmonize dynamic state and static state relation to gain LD output power instability to ±3% and internal orexternal pulse width modulation,relay soft and hardwer over-current protection and overvoltage shut-off.A continuously adjustable optical output power with high accuracy and stability has been obtained.
The paper describes a CW,non-colling,digital all-solid-stated LD pumped Nd:YVO4 laser driver which adopts microprocessor control,stability power of optics feedback about 10mW output power.The system is composed of stable current source,protection circuit,pulse driver,Si photo-detector amplified and hign-speed microprocessor control system.Based on error variety of nonlinear control curves of LD output laser power by Si photo-detector,we take advantage of window node PID control algorithm to achieve high stability of laser power and reduce error amends.Combining appropriate hardware and software in our driver,we have achieved a variety of protection features including the ability to match and harmonize dynamic state and static state relation to gain LD output power instability to ±3% and internal orexternal pulse width modulation,relay soft and hardwer over-current protection and overvoltage shut-off.A continuously adjustable optical output power with high accuracy and stability has been obtained.
2004, 28(3): 309-311.
Abstract:
An experimental setup of fiber Bragg gratings temperature sensing has been designed and founded.The influence of temperature on reflected wavelength shift of fiber Bragg gratings was studied.The wavelength shift of fiber Bragg gratings was measured respectively during temperature increasing and dropping.It was obtained that average reflected wavelength shift per Celsius centigrade degree when temperature increasing and dropping.Furthermore,the questions of the relations between wavelength shift and temperature variational direction and temperature sensing response speed was analyzed and discussed thoroughly.The results indicate that the response of fiber grating sensor is rapid.The relations between reflected wavelength shift and temperature have better linearity and the reflected wavelength shift is independent of temperature variational direction.
An experimental setup of fiber Bragg gratings temperature sensing has been designed and founded.The influence of temperature on reflected wavelength shift of fiber Bragg gratings was studied.The wavelength shift of fiber Bragg gratings was measured respectively during temperature increasing and dropping.It was obtained that average reflected wavelength shift per Celsius centigrade degree when temperature increasing and dropping.Furthermore,the questions of the relations between wavelength shift and temperature variational direction and temperature sensing response speed was analyzed and discussed thoroughly.The results indicate that the response of fiber grating sensor is rapid.The relations between reflected wavelength shift and temperature have better linearity and the reflected wavelength shift is independent of temperature variational direction.
2004, 28(3): 312-314,318.
Abstract:
Based on the investigation of Ar+laser-induced erythrocyte fluorescence spectra with various visible wavelengths under certain concentration of erythrocyte,it is found that there are plentiful peaks in the fluorescence spectra from 600nm to 860nm,and the peaks near 620nm change with the variation of exciting light wavelength.The results indicate that laser-induced erythrocyte fluorescence spectra are mainly due to numerous fluorophores from part thereof cytochrome,and pair-phosphatide on the erythrocyte membrane and the part thereof haem from the hemoglobin.In addition,there are not only laser excited erythrocyte fluorescence peaks but also the Raman scattered light by the erythrocyte in the near 620nm.The investigation may be useful for low lever laser induced tissue fluorescence spectra applied in medical treatment.
Based on the investigation of Ar+laser-induced erythrocyte fluorescence spectra with various visible wavelengths under certain concentration of erythrocyte,it is found that there are plentiful peaks in the fluorescence spectra from 600nm to 860nm,and the peaks near 620nm change with the variation of exciting light wavelength.The results indicate that laser-induced erythrocyte fluorescence spectra are mainly due to numerous fluorophores from part thereof cytochrome,and pair-phosphatide on the erythrocyte membrane and the part thereof haem from the hemoglobin.In addition,there are not only laser excited erythrocyte fluorescence peaks but also the Raman scattered light by the erythrocyte in the near 620nm.The investigation may be useful for low lever laser induced tissue fluorescence spectra applied in medical treatment.
2004, 28(3): 315-318.
Abstract:
The effect of some process parameters,such as solution concentration,spin speed,volatility and vapor absorbing ability of solvents,on the qualities of the spin coated polymer thin films on silicon substrate is discussed.An experiential equations was summarized to describe the relationship between the thickness of the PS films and the solution concentration and spin speed.Possible conditions that may lead to fault on films are analyzed,and some characters of the film such as the thickness,infra-red absorbing spectrum and topography are tested.
The effect of some process parameters,such as solution concentration,spin speed,volatility and vapor absorbing ability of solvents,on the qualities of the spin coated polymer thin films on silicon substrate is discussed.An experiential equations was summarized to describe the relationship between the thickness of the PS films and the solution concentration and spin speed.Possible conditions that may lead to fault on films are analyzed,and some characters of the film such as the thickness,infra-red absorbing spectrum and topography are tested.
2004, 28(3): 319-322.
Abstract:
To meet the current urgent requirement for some type of laser apparatus in the areas of aviation,spaceflight and national defence,etc,this paper successfully deals with developing optical-axis equations and its parallel degree for this type of laser apparatus with detailed analyzing and reasoning by using spatiality and geometry knowledge.At the same time,it also analyzes the problem of beaming spot getting into and out of incepting view field in detail.Then the formula of maximal distance of beaming spot not getting out of incepting view field is given in this paper.The research is valuable to the actual project design and application.
To meet the current urgent requirement for some type of laser apparatus in the areas of aviation,spaceflight and national defence,etc,this paper successfully deals with developing optical-axis equations and its parallel degree for this type of laser apparatus with detailed analyzing and reasoning by using spatiality and geometry knowledge.At the same time,it also analyzes the problem of beaming spot getting into and out of incepting view field in detail.Then the formula of maximal distance of beaming spot not getting out of incepting view field is given in this paper.The research is valuable to the actual project design and application.
2004, 28(3): 323-326.
Abstract:
Based on the aberrationless theory of self-focusing,the closed-form propagation expressions for Gaussian beams through a nonlinear gradient-index medium are derived by means of the ABCD law.By using the matrix optics method,the propagation properties of Gaussian beams through a nonlinear gradient-index lens are studied.It is shown that the nonlinearity and inhomogeneity of the medium,laser power and input beam parameter affect their propagation properties.
Based on the aberrationless theory of self-focusing,the closed-form propagation expressions for Gaussian beams through a nonlinear gradient-index medium are derived by means of the ABCD law.By using the matrix optics method,the propagation properties of Gaussian beams through a nonlinear gradient-index lens are studied.It is shown that the nonlinearity and inhomogeneity of the medium,laser power and input beam parameter affect their propagation properties.
2004, 28(3): 327-329.
Abstract:
The character of third-order dispersion in dispersion-manged solution system is studied.The influence of the third-order dispersion(TOD)on dispersion-managed soliton transmission system is investigated by means of variational method,and the evolution equations for the parameters of the optical Gaussian shaped pulse is derived.By simulation,we discussed the properties of the parameters under the influence of TOD.The nocuous influence and the necessarity of management of third-order dispersion is pointed out.
The character of third-order dispersion in dispersion-manged solution system is studied.The influence of the third-order dispersion(TOD)on dispersion-managed soliton transmission system is investigated by means of variational method,and the evolution equations for the parameters of the optical Gaussian shaped pulse is derived.By simulation,we discussed the properties of the parameters under the influence of TOD.The nocuous influence and the necessarity of management of third-order dispersion is pointed out.
2004, 28(3): 330-332,336.
Abstract:
Based on the theory of scalar diffraction,the diffraction of a uniform plane wave at two asymmetrical rectangular apertures is studied analytically and numerically. The transversal,on-axis and off-axis intensity distributions of the Fraunhofer and Fresnel diffraction are given and analyzed. It is shown that the Fraunhofer and Fresnel diffraction can be distinguished by the relative error of their maximum intensity. The result is consistent with that for the case of two circular apertures.
Based on the theory of scalar diffraction,the diffraction of a uniform plane wave at two asymmetrical rectangular apertures is studied analytically and numerically. The transversal,on-axis and off-axis intensity distributions of the Fraunhofer and Fresnel diffraction are given and analyzed. It is shown that the Fraunhofer and Fresnel diffraction can be distinguished by the relative error of their maximum intensity. The result is consistent with that for the case of two circular apertures.
2004, 28(3): 333-336.
Abstract:
Power propagation equations of multi-pumped fiber Raman amplifiers(FRA)are reasonably simplified,a mathematical model of composite Raman gain of multi-signals in dense wavelength division multiplexed system(DWDM)amplified by multi-pumped FRA is built,and the influence of stimulated Raman scattering(SRS)on Raman gain is analyzed.Based on such a simple and effective model,an algorithm to optimize pump wavelength distribution and input power is introduced and the ultra broad and flat Raman gain spectra are implemented.All the simulation and analyses supply valuable references for the application of multi-pumped FRA in DWDM system.
Power propagation equations of multi-pumped fiber Raman amplifiers(FRA)are reasonably simplified,a mathematical model of composite Raman gain of multi-signals in dense wavelength division multiplexed system(DWDM)amplified by multi-pumped FRA is built,and the influence of stimulated Raman scattering(SRS)on Raman gain is analyzed.Based on such a simple and effective model,an algorithm to optimize pump wavelength distribution and input power is introduced and the ultra broad and flat Raman gain spectra are implemented.All the simulation and analyses supply valuable references for the application of multi-pumped FRA in DWDM system.
