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RSS2003 Vol. 27, No. 1
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2003, 27(1): 1-3.
[Abstract]
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Abstract:
The 4×2 multi-segment-amplifier system is the hardcore of the high power solid-state laser driver which has been built in China,the energy conversion efficiency and structure of the laser facility have been decided by it. It is availability to adopt the project of module design to improve the maintainability and reduce the maintenance standby time,it also improves the running efficiency and the ratio between performance and price. In this paper,the development progress of a new high power solid-state laser multi-segment-amplifier with 29cm-square each aperture has been reported. The structure and characters of the multi-segment-amplifier are introduced here.
The 4×2 multi-segment-amplifier system is the hardcore of the high power solid-state laser driver which has been built in China,the energy conversion efficiency and structure of the laser facility have been decided by it. It is availability to adopt the project of module design to improve the maintainability and reduce the maintenance standby time,it also improves the running efficiency and the ratio between performance and price. In this paper,the development progress of a new high power solid-state laser multi-segment-amplifier with 29cm-square each aperture has been reported. The structure and characters of the multi-segment-amplifier are introduced here.
2003, 27(1): 4-7.
Abstract:
We examine the performance of dual header-pulse interval modulation (DH-PIM) for wireless infrared communication using intensity modulation with direct detection in the presence of both multipath intersymbol interference (ISI) and additive white Gaussian noise. We investigate the symbol structure,bandwidth requirements and error probability of DH-PIM. Results are compared with other modulation schemes,OOK,PPM and DPIM.
We examine the performance of dual header-pulse interval modulation (DH-PIM) for wireless infrared communication using intensity modulation with direct detection in the presence of both multipath intersymbol interference (ISI) and additive white Gaussian noise. We investigate the symbol structure,bandwidth requirements and error probability of DH-PIM. Results are compared with other modulation schemes,OOK,PPM and DPIM.
2003, 27(1): 8-10,13.
Abstract:
According to the investigation and analysis of pulsed laser parameters,we put forward a new principle of laser texturing of a new roll surface roughness profile (slight protuberance similitude of spherical cap) and successfully achieve the optimization predesign 3D surface roughness profile and size. In the experiment,based on the new principle of laser texturing,the laser parameters,such as pulse waveform,pulse energy,pulse duration,defocusing,are primely selected and matching. Consequently,the surface roughness profile and size have been successfully obtained. Furthermore,the influence rules between pulsed laser parameters and main profile parameters of roll have been analyzed and investigated. The results show the magnitude and space distribution of single pulse energy are the key factors of producing the new surface roughness profile and size.
According to the investigation and analysis of pulsed laser parameters,we put forward a new principle of laser texturing of a new roll surface roughness profile (slight protuberance similitude of spherical cap) and successfully achieve the optimization predesign 3D surface roughness profile and size. In the experiment,based on the new principle of laser texturing,the laser parameters,such as pulse waveform,pulse energy,pulse duration,defocusing,are primely selected and matching. Consequently,the surface roughness profile and size have been successfully obtained. Furthermore,the influence rules between pulsed laser parameters and main profile parameters of roll have been analyzed and investigated. The results show the magnitude and space distribution of single pulse energy are the key factors of producing the new surface roughness profile and size.
2003, 27(1): 11-13.
Abstract:
A non-selfsustained longitudinal discharge CO2 laser with pulsed preionization was studied for the first time. A novel spiral transversely pulsed preionization scheme is employed. The main discharge and output power of the laser are controlled by applied preionization pulses. The laser can operate free of ballast resistor. The maximum electro-optical efficiency of 19% is obtained.
A non-selfsustained longitudinal discharge CO2 laser with pulsed preionization was studied for the first time. A novel spiral transversely pulsed preionization scheme is employed. The main discharge and output power of the laser are controlled by applied preionization pulses. The laser can operate free of ballast resistor. The maximum electro-optical efficiency of 19% is obtained.
2003, 27(1): 14-15.
Abstract:
Several methods of the passivation of semiconductor laser facets are introduced. Using the technology of facet passivation,the authors treated semiconductor laser facets with several materials. It is found that the samples treated by P2S5/NH4OH and (NH4)2Sx have catastrophic optical damage (COD) at high output power.
Several methods of the passivation of semiconductor laser facets are introduced. Using the technology of facet passivation,the authors treated semiconductor laser facets with several materials. It is found that the samples treated by P2S5/NH4OH and (NH4)2Sx have catastrophic optical damage (COD) at high output power.
2003, 27(1): 16-18.
Abstract:
By means of CO2 laser induced liquid deposition technique,the local deposition of metal copper lines on the right sides of epoxy resin has been achieved from the aqueous solution for the first time. The catalytically active deposition center in the substrates has been observed and the micrographs of deposition copper lines have been also analysed based on scan electronic microscope(SEM),the electronic probe.
By means of CO2 laser induced liquid deposition technique,the local deposition of metal copper lines on the right sides of epoxy resin has been achieved from the aqueous solution for the first time. The catalytically active deposition center in the substrates has been observed and the micrographs of deposition copper lines have been also analysed based on scan electronic microscope(SEM),the electronic probe.
2003, 27(1): 19-20.
Abstract:
Based on geometric construction and theoretical derivation,the directions of the two kinds of optical axes in the biaxial crystal have been deduced.
Based on geometric construction and theoretical derivation,the directions of the two kinds of optical axes in the biaxial crystal have been deduced.
2003, 27(1): 21-23.
Abstract:
Zr65Al7.5Ni10Cu17.5 composite coatings on a Ti substrate were produced by laser cladding. The micro- structure of the coating was investigated by means of SEM,TEM and XRD. The results show that the coatings mainly consist of intermetallic phases,amorphous phase and nanocrystallitic phase.The intermetallic phases are Al2Zr3,CuZr2 and Zr2Ni.The nanocrystallitic phase is Al2Zr3 with P42 structure,whose cell parameters are a=b=76.18nm, c=69.85nm. The coating can be divided into three layers according to the difference of microstructure morphology:dendrite zone on the surface,fine crystallitic zone in the middle and bonding zone.
Zr65Al7.5Ni10Cu17.5 composite coatings on a Ti substrate were produced by laser cladding. The micro- structure of the coating was investigated by means of SEM,TEM and XRD. The results show that the coatings mainly consist of intermetallic phases,amorphous phase and nanocrystallitic phase.The intermetallic phases are Al2Zr3,CuZr2 and Zr2Ni.The nanocrystallitic phase is Al2Zr3 with P42 structure,whose cell parameters are a=b=76.18nm, c=69.85nm. The coating can be divided into three layers according to the difference of microstructure morphology:dendrite zone on the surface,fine crystallitic zone in the middle and bonding zone.
2003, 27(1): 24-25,28.
Abstract:
Based on the Collins formula in the frequency-domain and Hankel transform,propagation properties of flattened Gaussian,Bessel-super-Gaussian and Laguerre-Gaussian beams are studied.The results are compared with those obtained by means of the Collins formula in the space-domain,and the advantage of the method is discussed.
Based on the Collins formula in the frequency-domain and Hankel transform,propagation properties of flattened Gaussian,Bessel-super-Gaussian and Laguerre-Gaussian beams are studied.The results are compared with those obtained by means of the Collins formula in the space-domain,and the advantage of the method is discussed.
2003, 27(1): 26-28.
Abstract:
In the paper,the expression for axial intensity distribution of Bassel beams passing through an aperture lens separation system is derived based on Collins formula.The focal shift may be reversed,depending on the aperture lens separation.
In the paper,the expression for axial intensity distribution of Bassel beams passing through an aperture lens separation system is derived based on Collins formula.The focal shift may be reversed,depending on the aperture lens separation.
2003, 27(1): 29-30.
Abstract:
Based on Jones matrix theory,characteristic of 1/4 wavepalte with one side HR coating and the other side AR coating is analyzed in this paper. It shows that the film layers will induce oscillating of polarized light in the waveplate,which produces ripples effect in the passband.
Based on Jones matrix theory,characteristic of 1/4 wavepalte with one side HR coating and the other side AR coating is analyzed in this paper. It shows that the film layers will induce oscillating of polarized light in the waveplate,which produces ripples effect in the passband.
2003, 27(1): 31-33,36.
Abstract:
The weight average molecular weight,the hydrodynamic radius and gyration radius,the size distribution and the shape of the particles of flocculation PAC and PAC-V in pure water are studied with laser scattering technique.Accompanied with removal efficacy measurements,the study proves that the molecular weight,the size and shape of flocculation strongly affect the removal efficacy,and do not change with the concentration of flocculation,thus provides experimental evidence and theoretical basis for flocculating mechanism.
The weight average molecular weight,the hydrodynamic radius and gyration radius,the size distribution and the shape of the particles of flocculation PAC and PAC-V in pure water are studied with laser scattering technique.Accompanied with removal efficacy measurements,the study proves that the molecular weight,the size and shape of flocculation strongly affect the removal efficacy,and do not change with the concentration of flocculation,thus provides experimental evidence and theoretical basis for flocculating mechanism.
2003, 27(1): 34-36.
Abstract:
A compact all-solid-state Ti:sapphire regenerative laser amplifier without pre-pulse stretching has been developed. Laser pulses are stretched two times every round trip by a pair of prisms inside the cavity. The re-compressed 100fs pulses at 10kHz repetition rates are generated. The average output power is more than 0.2W.
A compact all-solid-state Ti:sapphire regenerative laser amplifier without pre-pulse stretching has been developed. Laser pulses are stretched two times every round trip by a pair of prisms inside the cavity. The re-compressed 100fs pulses at 10kHz repetition rates are generated. The average output power is more than 0.2W.
2003, 27(1): 37-39.
Abstract:
We have analysed the results of the photorefractive two-wave mixing in Ce:KNSBN controlled by an incoherent beam and performed experiment. Results show that the incoherent beam can effectively control the photorefractive two-wave coupling gain in a large range.The experimental results agree with the theory well.
We have analysed the results of the photorefractive two-wave mixing in Ce:KNSBN controlled by an incoherent beam and performed experiment. Results show that the incoherent beam can effectively control the photorefractive two-wave coupling gain in a large range.The experimental results agree with the theory well.
2003, 27(1): 40-43.
Abstract:
In the selective laser sintering(SLS) process,the low intensity and high porosity of the sintered part are still the key factors that restrict the industrial progress of the SLS technique.The interaction between the laser and the materials and the distribution of the three-dimension temperature field are important factors that affect the densification of the sintered part.They are also the essential basis for choosing the appropriate SLS process parameters.The interaction between the infrared laser and the polymer materials had been discussed in this paper.A numerical simulation model for SLS process is presented,which has been used to analyze the densification of the sintered part.The simulation results accord with those of the experiments.The results show that the SLS model can be used to estimate the densification of the sintered part effectively.
In the selective laser sintering(SLS) process,the low intensity and high porosity of the sintered part are still the key factors that restrict the industrial progress of the SLS technique.The interaction between the laser and the materials and the distribution of the three-dimension temperature field are important factors that affect the densification of the sintered part.They are also the essential basis for choosing the appropriate SLS process parameters.The interaction between the infrared laser and the polymer materials had been discussed in this paper.A numerical simulation model for SLS process is presented,which has been used to analyze the densification of the sintered part.The simulation results accord with those of the experiments.The results show that the SLS model can be used to estimate the densification of the sintered part effectively.
2003, 27(1): 44-46.
Abstract:
Modulation instability gain spectrum resulted from cross-phase modulation(XPM) in decreasing dispersion fiber (DDF) is presented from nonlinear Schrodinger equation. The results show that XPM-induced modulation instability exists not only in the anomalous-dispersion regime but also in the normal dispersion regime; what's more,the spectrum width of the former is wider than that of the latter. The spectrum width in DDF is wider than that of in ordinary dispersion fiber(ODF) and the gain peak is also higher. DDF is a good dispersion medium to produce modulation instability of XPM.
Modulation instability gain spectrum resulted from cross-phase modulation(XPM) in decreasing dispersion fiber (DDF) is presented from nonlinear Schrodinger equation. The results show that XPM-induced modulation instability exists not only in the anomalous-dispersion regime but also in the normal dispersion regime; what's more,the spectrum width of the former is wider than that of the latter. The spectrum width in DDF is wider than that of in ordinary dispersion fiber(ODF) and the gain peak is also higher. DDF is a good dispersion medium to produce modulation instability of XPM.
2003, 27(1): 47-49.
Abstract:
The matrix factorization and equivalent transformation of periodic misaligned optical systems are studied by using the matrix method in optics and generalized Sylvester theorem. It is shown that the periodic misaligned systems can be simplified to a combination of a thin aligned lens and two thin prisms.
The matrix factorization and equivalent transformation of periodic misaligned optical systems are studied by using the matrix method in optics and generalized Sylvester theorem. It is shown that the periodic misaligned systems can be simplified to a combination of a thin aligned lens and two thin prisms.
2003, 27(1): 50-52.
Abstract:
The mathematical model of linear absorption frequency stabilization is established. According to the model for FM laser passing the absorber,the error signal of different modulation frequency and modulation index is obtained. Then the optimal modulation frequency and the optimal modulation index is given.
The mathematical model of linear absorption frequency stabilization is established. According to the model for FM laser passing the absorber,the error signal of different modulation frequency and modulation index is obtained. Then the optimal modulation frequency and the optimal modulation index is given.
2003, 27(1): 53-54,64.
Abstract:
In this paper,the distribution of transmitted beam and the factor that affect the distortion are analyzed when the beam incidents forward.When the prism is used inversely,it is equal to Rochon prism.Equations are given for the deviation angle and the splitting angle.
In this paper,the distribution of transmitted beam and the factor that affect the distortion are analyzed when the beam incidents forward.When the prism is used inversely,it is equal to Rochon prism.Equations are given for the deviation angle and the splitting angle.
2003, 27(1): 55-57,72.
Abstract:
Starting from the Collins formula,focal shifts of flattened Gaussian beams(FGBs)passing through an aperture lens are studied and illustr ated with detailed numerical examples.It is shown that focal shifts of apertured FGBs not only depend on the beam order N,Fresnel number Fw associated with the beam,but also depend on the Fresnel number Fa associated with the aperture.In comparison with the unapertured case,there still exist fo cal shifts even for the case of the large Fresnel number Fw.
Starting from the Collins formula,focal shifts of flattened Gaussian beams(FGBs)passing through an aperture lens are studied and illustr ated with detailed numerical examples.It is shown that focal shifts of apertured FGBs not only depend on the beam order N,Fresnel number Fw associated with the beam,but also depend on the Fresnel number Fa associated with the aperture.In comparison with the unapertured case,there still exist fo cal shifts even for the case of the large Fresnel number Fw.
2003, 27(1): 58-61,67.
Abstract:
The three phases of laser used in the processing of the cylinder wall,big focus slow scan screw laser quenching,small focus quick scan net-lines laser quenching and laser honing,are introduced in this article. Through comparation,the advantage of laser honing is indicatated. And then the processing method of laser honing is discussed. The application characters of YAG laser and excimer laser in laser honing are compared and analysed from the following factors,including the quality of laser beam,the theory of process and the technique of process.
The three phases of laser used in the processing of the cylinder wall,big focus slow scan screw laser quenching,small focus quick scan net-lines laser quenching and laser honing,are introduced in this article. Through comparation,the advantage of laser honing is indicatated. And then the processing method of laser honing is discussed. The application characters of YAG laser and excimer laser in laser honing are compared and analysed from the following factors,including the quality of laser beam,the theory of process and the technique of process.
2003, 27(1): 62-64.
Abstract:
In this paper,the static transmission of phosphate laser disk glass used in high power laser amplifier is measured. In normal research condition,the average static transmission at 1.054μm incident beam with four pieces of phosphate laser glass(N31) disposed by Brewster angle is 94.5%,the loss coefficient is 0.294% cm-1,the average non-activity absorption coefficient is 0.146% cm-1,this N31 glass is made in China. Based on them,the small signal gain coefficient value is amended and reached up to 5.25% cm-1.
In this paper,the static transmission of phosphate laser disk glass used in high power laser amplifier is measured. In normal research condition,the average static transmission at 1.054μm incident beam with four pieces of phosphate laser glass(N31) disposed by Brewster angle is 94.5%,the loss coefficient is 0.294% cm-1,the average non-activity absorption coefficient is 0.146% cm-1,this N31 glass is made in China. Based on them,the small signal gain coefficient value is amended and reached up to 5.25% cm-1.
2003, 27(1): 65-67.
Abstract:
In this paper,impedance characteristic of capillary filled with Ar gas is first presented in the experiment. This is very important for capillary discharge pumped X-ray laser experiment to find optimal discharge condition.
In this paper,impedance characteristic of capillary filled with Ar gas is first presented in the experiment. This is very important for capillary discharge pumped X-ray laser experiment to find optimal discharge condition.
2003, 27(1): 68-70.
Abstract:
The present application and study situation of laser technique on the synthesis of nanopowders are reviewed. The process,raw materials and characters of different nanopowders synthesis by laser are clarified. The application of laser technique on Si/C/N and other nanopowders synthesis are analyzed concretely, and finally the comments on the application prospect of this technique is given.
The present application and study situation of laser technique on the synthesis of nanopowders are reviewed. The process,raw materials and characters of different nanopowders synthesis by laser are clarified. The application of laser technique on Si/C/N and other nanopowders synthesis are analyzed concretely, and finally the comments on the application prospect of this technique is given.
2003, 27(1): 71-72.
Abstract:
Based on the principal of magnetically stabilized discharge,a new electrode configuration is designed. Characteristics of the discharge are studied for this transverse flow CO2 lasers with 2-dimensional orthogonal system.Large volume homogeneous discharge has obtained and the input power is 15kW.
Based on the principal of magnetically stabilized discharge,a new electrode configuration is designed. Characteristics of the discharge are studied for this transverse flow CO2 lasers with 2-dimensional orthogonal system.Large volume homogeneous discharge has obtained and the input power is 15kW.
2003, 27(1): 73-75.
Abstract:
A dynamic micro-displacement measurement system based on Doppler effect is introduced. The system includes He-Ne laser source,frequency conversion and direction discrimination,the high-speed CCD video signal gather system,the processing system of computer and interference fringes handling software wraps. The precision,sensitivity and stability in this system have been improved compared with traditional measurement technique,the full automatic measurement of micro-displacement is realized.
A dynamic micro-displacement measurement system based on Doppler effect is introduced. The system includes He-Ne laser source,frequency conversion and direction discrimination,the high-speed CCD video signal gather system,the processing system of computer and interference fringes handling software wraps. The precision,sensitivity and stability in this system have been improved compared with traditional measurement technique,the full automatic measurement of micro-displacement is realized.
2003, 27(1): 76-77,80.
Abstract:
This paper introduces the method to describe the polarization state of light wave in complex plane. It also introduces the method to settle the transfer problem of the polarization state using the transfer function when polarized light passes through retardation sheet. The new method has a visualized and simple feature,and is applicable for different transformation of polarization states.
This paper introduces the method to describe the polarization state of light wave in complex plane. It also introduces the method to settle the transfer problem of the polarization state using the transfer function when polarized light passes through retardation sheet. The new method has a visualized and simple feature,and is applicable for different transformation of polarization states.
2003, 27(1): 78-80.
Abstract:
The principles of chirp filtering in fractional Fourier domain are discussed in this paper. After introducing optical fractional Fourier transform into digital image processing,we present a new method to eliminate chirp noise of digital images by filtering in the fractional Fourier domain. The filtering effects of this method and conventional Fourier domain filtering are compared and satisfying simulation results are obtained.
The principles of chirp filtering in fractional Fourier domain are discussed in this paper. After introducing optical fractional Fourier transform into digital image processing,we present a new method to eliminate chirp noise of digital images by filtering in the fractional Fourier domain. The filtering effects of this method and conventional Fourier domain filtering are compared and satisfying simulation results are obtained.
