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RSS2001 Vol. 25, No. 3
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2001, 25(3): 161-165.
[Abstract]
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Abstract:
This paper gives a depiction of the recent advancement optoelectronic vibration sensors, which play an indispensable part in the field of vibration measurement.The improvement of related techniques,the developing trend and some hot subjects are introduced.
This paper gives a depiction of the recent advancement optoelectronic vibration sensors, which play an indispensable part in the field of vibration measurement.The improvement of related techniques,the developing trend and some hot subjects are introduced.
2001, 25(3): 166-169.
Abstract:
The development of nonlinear optical (NLO) materials is briefly reviewed in this paper.Basic structures, NLO properties and optical limiting (OL) performances of mental cluster compounds are introduced in detail.
The development of nonlinear optical (NLO) materials is briefly reviewed in this paper.Basic structures, NLO properties and optical limiting (OL) performances of mental cluster compounds are introduced in detail.
2001, 25(3): 170-173.
Abstract:
The distinctive acoustic signal emitted by plasma while laser welding diamond saw is regarded as a signal which is produced when a carrier wave with frequency of 16kHz is modulated with a periodical signal with frequency of 300Hz.A method to obtain the diagnostic signal, the acoustic feedback control system and the principle of laser welding diamond saw are described in the paper.Experimental results prove that in terms of welding qualities, acoustic feedback method is better than ordinary laser welding method.
The distinctive acoustic signal emitted by plasma while laser welding diamond saw is regarded as a signal which is produced when a carrier wave with frequency of 16kHz is modulated with a periodical signal with frequency of 300Hz.A method to obtain the diagnostic signal, the acoustic feedback control system and the principle of laser welding diamond saw are described in the paper.Experimental results prove that in terms of welding qualities, acoustic feedback method is better than ordinary laser welding method.
2001, 25(3): 174-177.
Abstract:
Micro machined defects can be introduced into a semiconductor laser to improve spectral characteristics of the F-P laser.Based on ray trace method, an expression of the output spectrum from a micro machined F-P semiconductor laser including two defects has been deduced.With the aid of the expression,the difference ΔN between the nominal threshold carrier density Nth and actual carrier density N of the laser can be determined, and the side mode suppression can be specified.
Micro machined defects can be introduced into a semiconductor laser to improve spectral characteristics of the F-P laser.Based on ray trace method, an expression of the output spectrum from a micro machined F-P semiconductor laser including two defects has been deduced.With the aid of the expression,the difference ΔN between the nominal threshold carrier density Nth and actual carrier density N of the laser can be determined, and the side mode suppression can be specified.
2001, 25(3): 178-182.
Abstract:
The study of X-ray laser in capillary discharge is very active and a new concept for short wave laser research has been put forward.The detailed evolution of X-ray laser in capillary discharge is summarized in the paper and the important development factor in the future is pointed out.This work is valuable to the research of X-ray lasers in capillary discharge by electron collision excitation regimes.
The study of X-ray laser in capillary discharge is very active and a new concept for short wave laser research has been put forward.The detailed evolution of X-ray laser in capillary discharge is summarized in the paper and the important development factor in the future is pointed out.This work is valuable to the research of X-ray lasers in capillary discharge by electron collision excitation regimes.
2001, 25(3): 183-187.
Abstract:
Besides general review of the inverse problems in optics,this paper exactly analyzes two important inverse problems,namely,the coherent mode decomposition of lasers(inverse problem of the M2 factor) and inverse problem of a pulsed laser amplifier system.Finally,some relevant subjects are briefly discussed.
Besides general review of the inverse problems in optics,this paper exactly analyzes two important inverse problems,namely,the coherent mode decomposition of lasers(inverse problem of the M2 factor) and inverse problem of a pulsed laser amplifier system.Finally,some relevant subjects are briefly discussed.
2001, 25(3): 188-192.
Abstract:
Based on M-B equation,the dynamic performances of CO2 laser are analyzed.From the point of experiments,various techniques used to produce chaos in a CO2 laser are briefly introduced.Some feasible ways used to lead multi-electrode-pair CO2 laser to chaotic regime are suggested tentatively.
Based on M-B equation,the dynamic performances of CO2 laser are analyzed.From the point of experiments,various techniques used to produce chaos in a CO2 laser are briefly introduced.Some feasible ways used to lead multi-electrode-pair CO2 laser to chaotic regime are suggested tentatively.
2001, 25(3): 192-195.
Abstract:
Based on the beam propagation equation,the hyperbolic-fit mothed is used to calculate the M2 factor of super-Gaussian beams passing through a spherically aberrated lens.The power in the bucket(PIB) at the geometrical and real focal planes of super-Gaussian beams with spherically aberration is also studied.With M2 factor and PIB as the criteria for laser beam quality,detailed numerical calculations are performed to illustrate the effects of the spherically aberrated lens on the beam quality of super-Gaussian beams.The result is useful for some practical application.
Based on the beam propagation equation,the hyperbolic-fit mothed is used to calculate the M2 factor of super-Gaussian beams passing through a spherically aberrated lens.The power in the bucket(PIB) at the geometrical and real focal planes of super-Gaussian beams with spherically aberration is also studied.With M2 factor and PIB as the criteria for laser beam quality,detailed numerical calculations are performed to illustrate the effects of the spherically aberrated lens on the beam quality of super-Gaussian beams.The result is useful for some practical application.
2001, 25(3): 196-199.
Abstract:
Based on practical requirements,the rate equations have been used to determine the pump currents for semiconductor lasers in order to obtain the required optical pulses.Analytical expressions of the injection currents needed to generate Gaussian and reshaped optical pulses have been deduced.
Based on practical requirements,the rate equations have been used to determine the pump currents for semiconductor lasers in order to obtain the required optical pulses.Analytical expressions of the injection currents needed to generate Gaussian and reshaped optical pulses have been deduced.
2001, 25(3): 199-202.
Abstract:
Based on experiments,the ignition threshold of metal covered energetic material by Nd:YAG laser beam is investigated.Then the process and mechanism are analyzed.Finally,the effects of laser spot size and incident angle on ignition threshold are discussed.
Based on experiments,the ignition threshold of metal covered energetic material by Nd:YAG laser beam is investigated.Then the process and mechanism are analyzed.Finally,the effects of laser spot size and incident angle on ignition threshold are discussed.
2001, 25(3): 203-205.
Abstract:
With Ti:sapphire laser pumping Cr4+,Nd3+:YAG monolithic crystal,the self-Q-switched laser output is obtained with wavelength of 1.064μm,pulse with of 12ns.The laser output is highly stable single-longitudinal-mode,the pumping threshold power is 90mW and the slope efficiency is up to 22%.The use of laser host crystal co doped with saturable absorber and laser gain medium can lead to the development of monolithic self-Q-switched solid state lasers.
With Ti:sapphire laser pumping Cr4+,Nd3+:YAG monolithic crystal,the self-Q-switched laser output is obtained with wavelength of 1.064μm,pulse with of 12ns.The laser output is highly stable single-longitudinal-mode,the pumping threshold power is 90mW and the slope efficiency is up to 22%.The use of laser host crystal co doped with saturable absorber and laser gain medium can lead to the development of monolithic self-Q-switched solid state lasers.
2001, 25(3): 206-208.
Abstract:
Adjusting Q slowly cavity flowing empty technology is a method that renovates pulses in the time field.The application of non uniform reflection mirror cavity is able to change the space section structure of the optical wave field.Hybrid application of these two technologies in a ns grade Q-switched pulse Nd:YAG laser makes it available to renovate pulses in time and space at the meantime.
Adjusting Q slowly cavity flowing empty technology is a method that renovates pulses in the time field.The application of non uniform reflection mirror cavity is able to change the space section structure of the optical wave field.Hybrid application of these two technologies in a ns grade Q-switched pulse Nd:YAG laser makes it available to renovate pulses in time and space at the meantime.
2001, 25(3): 209-213.
Abstract:
In the paper,the preparation of ZnO/TiO2 multi layer film with S G method is introduced and the gas sensitive optical property of the film is studied.The film is very sensitive to ammonia.It's light transmittance increases considerably and monotonously as the gas concentration increases.The sensitive wavelength band extends to full visible spectrum.This material is of great practical value for gas sensing fiber.The gas sensitive mechanism and high selectivity mechanism are also discussed.
In the paper,the preparation of ZnO/TiO2 multi layer film with S G method is introduced and the gas sensitive optical property of the film is studied.The film is very sensitive to ammonia.It's light transmittance increases considerably and monotonously as the gas concentration increases.The sensitive wavelength band extends to full visible spectrum.This material is of great practical value for gas sensing fiber.The gas sensitive mechanism and high selectivity mechanism are also discussed.
2001, 25(3): 214-217.
Abstract:
2001, 25(3): 217-220.
Abstract:
In this paper,the movement of the laser head during laser processing is analyzed.With the help of object oriented method and tool kit ARX on mechanical desktop(MDT),position data and normal data from model in MDT are extracted,and them these data are transferred to machine data,finally NC codes for processing are generated.The developed laser processing CAM system is practical with high speed and high efficiency for laser processing of complex 3D parts.
In this paper,the movement of the laser head during laser processing is analyzed.With the help of object oriented method and tool kit ARX on mechanical desktop(MDT),position data and normal data from model in MDT are extracted,and them these data are transferred to machine data,finally NC codes for processing are generated.The developed laser processing CAM system is practical with high speed and high efficiency for laser processing of complex 3D parts.
2001, 25(3): 221-224.
Abstract:
Based on the structural property of semiconductor and the enhanced effect of spontaneous emission in cavity quantum electron dynamics,a simple rate equation is derived for micro-cavity lasers.Transient response and dynamic modulation characteristics of micro-cavity lasers are discussed.The dependence of threshold,turn on delay and relaxation oscillation frequency on spontaneous emission factor,inject current and the length of the cavity is analyzed.The results construct the theoretical basis to improve the high frequency modulation characteristics of micro-cavity lasers and to optimize their structures.
Based on the structural property of semiconductor and the enhanced effect of spontaneous emission in cavity quantum electron dynamics,a simple rate equation is derived for micro-cavity lasers.Transient response and dynamic modulation characteristics of micro-cavity lasers are discussed.The dependence of threshold,turn on delay and relaxation oscillation frequency on spontaneous emission factor,inject current and the length of the cavity is analyzed.The results construct the theoretical basis to improve the high frequency modulation characteristics of micro-cavity lasers and to optimize their structures.
2001, 25(3): 225-228.
Abstract:
With the help of amplification method, the small signal gain of a gas dynamic CO2 laser is measured respectively under toluene and alcohol driving conditions.The experiments show that with toluene used as fuel,the small signal gain may reach 0.62m-1,which is by far higher than that with alcohol used as fuel.In conclusion,toluene is an optimum liquid fuel for combustion driven gas dynamic CO2 laser
With the help of amplification method, the small signal gain of a gas dynamic CO2 laser is measured respectively under toluene and alcohol driving conditions.The experiments show that with toluene used as fuel,the small signal gain may reach 0.62m-1,which is by far higher than that with alcohol used as fuel.In conclusion,toluene is an optimum liquid fuel for combustion driven gas dynamic CO2 laser
2001, 25(3): 229-232.
Abstract:
Based on the standard nonlinear Schrodinger equation,a differential equation describing the evolution of Gaussian beams travelling inside a Kerr medium has been deduced.With the aid of potential function,the propagation properties of the beams have been studied.The results reveal that the evolution of the beams may take three forms, which are confirmed by numerical calculations.
Based on the standard nonlinear Schrodinger equation,a differential equation describing the evolution of Gaussian beams travelling inside a Kerr medium has been deduced.With the aid of potential function,the propagation properties of the beams have been studied.The results reveal that the evolution of the beams may take three forms, which are confirmed by numerical calculations.
2001, 25(3): 232-237.
Abstract:
This paper gives a review of experiments related to the foundations of quantum physics,i.e.quantum entanglement.A series of late developments in the field of quantum entanglement,especially two photon and three-photon entanglement experiments which are based on the process of spontaneous parametric down conversion,is introduced.
This paper gives a review of experiments related to the foundations of quantum physics,i.e.quantum entanglement.A series of late developments in the field of quantum entanglement,especially two photon and three-photon entanglement experiments which are based on the process of spontaneous parametric down conversion,is introduced.
2001, 25(3): 238-241.
Abstract:
A 20kW CO2 laser was applied to explore the plasma shielding mechanism by studying the effect of plasma height on the welding depth and the focusing laser beam.On the basic phenomenon that the laser induced plasma would sustain for a while even after the laser beam passed through out of the workpiece during high power CO2 laser welding, a simple and effective method is developed to record the effect of plasma on the focusing laser beam.It is found that the laser induced plasma enlarges the diameter of the focused laser beam and the focus shifts downward significantly.This "lensing effect" of the laser induced plasma becomes more serious with the increase of the plasma height.Compared with the absorption of plasma, the "lensing effect" is the main mechanism for plasma shielding in the process of high power CO2 laser welding.
A 20kW CO2 laser was applied to explore the plasma shielding mechanism by studying the effect of plasma height on the welding depth and the focusing laser beam.On the basic phenomenon that the laser induced plasma would sustain for a while even after the laser beam passed through out of the workpiece during high power CO2 laser welding, a simple and effective method is developed to record the effect of plasma on the focusing laser beam.It is found that the laser induced plasma enlarges the diameter of the focused laser beam and the focus shifts downward significantly.This "lensing effect" of the laser induced plasma becomes more serious with the increase of the plasma height.Compared with the absorption of plasma, the "lensing effect" is the main mechanism for plasma shielding in the process of high power CO2 laser welding.
