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RSS1998 Vol. 22, No. 3
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1998, 22(3): 129-132.
[Abstract]
[PDF 274KB]
Abstract:
The zero current switching quasi resonant converter for high power Fast Axial Flow CO2 gas laser is studied in this paper.The operating principle and circuit structure of the power supply are discussed.The resonant converter is simulated by computer and the operating waveforms are obtained.Compared with the PWM hard switching converter,the outstanding characteristics of the ZCS-QR converter are presented.The resonant converter is especially attraction for high frequency,high power application.
The zero current switching quasi resonant converter for high power Fast Axial Flow CO2 gas laser is studied in this paper.The operating principle and circuit structure of the power supply are discussed.The resonant converter is simulated by computer and the operating waveforms are obtained.Compared with the PWM hard switching converter,the outstanding characteristics of the ZCS-QR converter are presented.The resonant converter is especially attraction for high frequency,high power application.
1998, 22(3): 132-135.
Abstract:
In this paper,we present a new real time input arrangement which combines the 90º prism and the high pass filter.The contrast of the fingerprint pattern introduced by the presented input arrangement is far higher than that introduced by the prism.The real time fingerprint verification system with proposed input arrangement is demonstrated,and the experimental results show that it has a lower false match rate and it is simple,practical and inexpensive.
In this paper,we present a new real time input arrangement which combines the 90º prism and the high pass filter.The contrast of the fingerprint pattern introduced by the presented input arrangement is far higher than that introduced by the prism.The real time fingerprint verification system with proposed input arrangement is demonstrated,and the experimental results show that it has a lower false match rate and it is simple,practical and inexpensive.
1998, 22(3): 136-139.
Abstract:
The oblique incident laser beam is projects on a metal plate,then reflected and imaged on a photocell with a lens.While the plate has a movement,the laser spot will depart from the photocell.Using a turning mirror to make the laser beam to scan a special position,the laser image spot can return to photocell.By measurement of the scanning angle of the laser beam,the displacement of the metal plate can be calculated.So the method can be applied to measure the thickness of the metal plate.In order to eliminate the influence of the variation of reflectance of metal surface,the correct method is presented.The method is no contact and can be used in real time measurements.
The oblique incident laser beam is projects on a metal plate,then reflected and imaged on a photocell with a lens.While the plate has a movement,the laser spot will depart from the photocell.Using a turning mirror to make the laser beam to scan a special position,the laser image spot can return to photocell.By measurement of the scanning angle of the laser beam,the displacement of the metal plate can be calculated.So the method can be applied to measure the thickness of the metal plate.In order to eliminate the influence of the variation of reflectance of metal surface,the correct method is presented.The method is no contact and can be used in real time measurements.
1998, 22(3): 139-143.
Abstract:
In this paper,we first discuss the effect of parameters choosing on phase space reconstruction through the chaotic signal and the signal received from the oceanic lidar.Then we reconstruct the space of the three types signals of determinate signal(cosine),random signal,chaos and experimental signal.We preliminarily know the regular pattern to choose the parameters and the phase space character of the three types of the signals,and find that the phase space of the experimental signal is similar to chaos',but different from random's
In this paper,we first discuss the effect of parameters choosing on phase space reconstruction through the chaotic signal and the signal received from the oceanic lidar.Then we reconstruct the space of the three types signals of determinate signal(cosine),random signal,chaos and experimental signal.We preliminarily know the regular pattern to choose the parameters and the phase space character of the three types of the signals,and find that the phase space of the experimental signal is similar to chaos',but different from random's
1998, 22(3): 144-146.
Abstract:
A numerical method for analyzing of the chirping characteristics of a traveling wave semiconductor optical amplifier is developed.Including the factors of the finite facet reflectivities and the spontaneous emission.The theoretical research show that introduce of these factors will reduce the amplitude of nonlinear frequency chirping imposed on amplified light pulse.
A numerical method for analyzing of the chirping characteristics of a traveling wave semiconductor optical amplifier is developed.Including the factors of the finite facet reflectivities and the spontaneous emission.The theoretical research show that introduce of these factors will reduce the amplitude of nonlinear frequency chirping imposed on amplified light pulse.
1998, 22(3): 147-152.
Abstract:
A comprehensive summarization for the developing history of airborne oceanic lidar is presented.Comment on the each phases is shown.Finally,the future of the technique is prospected.
A comprehensive summarization for the developing history of airborne oceanic lidar is presented.Comment on the each phases is shown.Finally,the future of the technique is prospected.
1998, 22(3): 153-158.
Abstract:
In this paper,the application of femtosecond spectroscopy in studying ultrafast phenomena is summarized first.Then,applications of differential transmission spectroscopy,one of important femtosecond spectroscopy,in studying ultrafast relaxation process are described in details,including the principle and experimental technique of detecting dynamics of excited states for isolated molecular system and the annihilation dynamics of excitons in crystals.Some examples are given.Finally,some problems met in studying ultrafast process by differential transmission spectroscopy and their solutions are discussed.
In this paper,the application of femtosecond spectroscopy in studying ultrafast phenomena is summarized first.Then,applications of differential transmission spectroscopy,one of important femtosecond spectroscopy,in studying ultrafast relaxation process are described in details,including the principle and experimental technique of detecting dynamics of excited states for isolated molecular system and the annihilation dynamics of excitons in crystals.Some examples are given.Finally,some problems met in studying ultrafast process by differential transmission spectroscopy and their solutions are discussed.
1998, 22(3): 158-160.
Abstract:
A diode laser pumped CW-Cr:LiSAF tunable laser is reported.An output of 2mW with an incident pump power of 148mW,wavelength of 866nm and a tunable range of 835.5～893.8nm are obtained.The experimental results are discussed as well.
A diode laser pumped CW-Cr:LiSAF tunable laser is reported.An output of 2mW with an incident pump power of 148mW,wavelength of 866nm and a tunable range of 835.5～893.8nm are obtained.The experimental results are discussed as well.
1998, 22(3): 161-163.
Abstract:
According to design optimum and theoretical analysis of the CO2 laser,the techniques of the magnetically confined exciting,the transverse flow in two normal axes and multifolded cavity are employed.The transverse distribution of gain region and gain coefficient are analyzed and measured by means of amplification method.The results show that the gain coefficient of the laser is larger and the gain region is wider than ordinary transverse flow CO2 laser and the laser has the excellent TEM00 output mode with the multifolded cavity.
According to design optimum and theoretical analysis of the CO2 laser,the techniques of the magnetically confined exciting,the transverse flow in two normal axes and multifolded cavity are employed.The transverse distribution of gain region and gain coefficient are analyzed and measured by means of amplification method.The results show that the gain coefficient of the laser is larger and the gain region is wider than ordinary transverse flow CO2 laser and the laser has the excellent TEM00 output mode with the multifolded cavity.
1998, 22(3): 163-165.
Abstract:
This paper described the novel collimation technique of semiconductor laser with auto focus optical fiber.The structure is simple and easy to adjust.The experimental research shows that larger divergent angle of semiconductor laser is turned to 0.01º level.So,auto focus optical fiber for collimation of semiconductor laser is suitable to apply in the field of precision measurement.
This paper described the novel collimation technique of semiconductor laser with auto focus optical fiber.The structure is simple and easy to adjust.The experimental research shows that larger divergent angle of semiconductor laser is turned to 0.01º level.So,auto focus optical fiber for collimation of semiconductor laser is suitable to apply in the field of precision measurement.
1998, 22(3): 166-169.
Abstract:
In this paper , using the generalized Huyg en-s Fr esnel diffr action integral, the fo cusing properties of tw isted Gaussian-Schell model beams through an aperture lens have been studied in detail.Numerical calculation r esults demonstr ate that the focusing properties of tw isted Gaussian Schell-model beams are dependent on Fresnel number of optical systems, trucat ion parameter , coherent paramenter and twisted parameter.
In this paper , using the generalized Huyg en-s Fr esnel diffr action integral, the fo cusing properties of tw isted Gaussian-Schell model beams through an aperture lens have been studied in detail.Numerical calculation r esults demonstr ate that the focusing properties of tw isted Gaussian Schell-model beams are dependent on Fresnel number of optical systems, trucat ion parameter , coherent paramenter and twisted parameter.
1998, 22(3): 169-171.
Abstract:
We summarize the technology development of fullerenes in the areas of both the excited state absorption optical limiting and the hybrid optical limiting including the exited state absorption and other nonlinear optical effects.The main research tasks in the future are also discussed.
We summarize the technology development of fullerenes in the areas of both the excited state absorption optical limiting and the hybrid optical limiting including the exited state absorption and other nonlinear optical effects.The main research tasks in the future are also discussed.
1998, 22(3): 172-176.
Abstract:
In this paper,the method of wave front aberration is employed to study the transformation properties of semiconductor laser beams.Using the optical system composed of a cylinder lens and a collimation lens is a useful method to correct the astigmatism of the semiconductor laser beam.This paper presents the exact design formulas of cylinder lens,which respectively correspond to two arrangements of the cylinder lens placed in front of or behind the object lens.And this paper points out if the waist position of semiconductor laser beam meets the condition of x2os>-fLf'L,the cylinder lens should be placed in front of the object lens,reversely the cylinder lens should be placed behind the object lens and simultaneously the position of the cylinder lens should meet the condition of x'C>-fLf'L.Finally,the optimun position of the cylinder lens in the correction astigmatism system for the semiconductor laser beam is derived.
In this paper,the method of wave front aberration is employed to study the transformation properties of semiconductor laser beams.Using the optical system composed of a cylinder lens and a collimation lens is a useful method to correct the astigmatism of the semiconductor laser beam.This paper presents the exact design formulas of cylinder lens,which respectively correspond to two arrangements of the cylinder lens placed in front of or behind the object lens.And this paper points out if the waist position of semiconductor laser beam meets the condition of x2os>-fLf'L,the cylinder lens should be placed in front of the object lens,reversely the cylinder lens should be placed behind the object lens and simultaneously the position of the cylinder lens should meet the condition of x'C>-fLf'L.Finally,the optimun position of the cylinder lens in the correction astigmatism system for the semiconductor laser beam is derived.
1998, 22(3): 176-180.
Abstract:
Based on the experimental research,the simulation analysis of magnetically confined discharge circuit has been made.The characteristics of the discharge current and voltage are experimentally analyzed.The results will put the base for designing this discharge circuit.
Based on the experimental research,the simulation analysis of magnetically confined discharge circuit has been made.The characteristics of the discharge current and voltage are experimentally analyzed.The results will put the base for designing this discharge circuit.
1998, 22(3): 180-184.
Abstract:
The reliability of gas laser refers to the ability of finishing stipulated function in stipulated condition and time.He Ne laser is a main product of gas lasers in our country,and has fairly scale at the end of 70's.Science 1981,more than 20 units had been organized to take part in reliability test research of gas lasers in the charge of Nanjing Institute of Technology.After several years,the lost efficiency physical model,accelerated factors and the way of accelerated life test were found.This paper introduces the Fudan University's work.
The reliability of gas laser refers to the ability of finishing stipulated function in stipulated condition and time.He Ne laser is a main product of gas lasers in our country,and has fairly scale at the end of 70's.Science 1981,more than 20 units had been organized to take part in reliability test research of gas lasers in the charge of Nanjing Institute of Technology.After several years,the lost efficiency physical model,accelerated factors and the way of accelerated life test were found.This paper introduces the Fudan University's work.
1998, 22(3): 185-188.
Abstract:
This paper presents a laser optical fiber system of detecting the variable figure area with CCD,Introducing optic image and computer processing techniques. Adopting a good method that it can calculate quickly and simultaneously the figure boundary locus surrounding area recorded by CCD which comes into being gradually, realizing the simultaneous indications of imagery and its area.This system is char acteristic of high efficiency and auto mation when we detecting the extent of the ice-melt in the front of car window.It shows a meaning of practice. On engineering measuring,it is of reference value.
This paper presents a laser optical fiber system of detecting the variable figure area with CCD,Introducing optic image and computer processing techniques. Adopting a good method that it can calculate quickly and simultaneously the figure boundary locus surrounding area recorded by CCD which comes into being gradually, realizing the simultaneous indications of imagery and its area.This system is char acteristic of high efficiency and auto mation when we detecting the extent of the ice-melt in the front of car window.It shows a meaning of practice. On engineering measuring,it is of reference value.
1998, 22(3): 188-190.
Abstract:
In this paper,the thermal effect of focussing lens in the laser processing was studied from the theoretical calculation and the experiment.The influence of the thermal effect of focussing lens for the laser welding technolgoy was discussed.Some rules and the preventive methods were obtained.The suggestions of the research shows quite signification to improvt the quality and technology of the laser welding.
In this paper,the thermal effect of focussing lens in the laser processing was studied from the theoretical calculation and the experiment.The influence of the thermal effect of focussing lens for the laser welding technolgoy was discussed.Some rules and the preventive methods were obtained.The suggestions of the research shows quite signification to improvt the quality and technology of the laser welding.
1998, 22(3): 191-195.
Abstract:
In order to acquire a high intensity and minimal scanning beam spot,diffraction analysis and optimal results have been presented.The theory can be applied to CD,CD-ROM,WORM,MOD and other optical disk storage systems.
In order to acquire a high intensity and minimal scanning beam spot,diffraction analysis and optimal results have been presented.The theory can be applied to CD,CD-ROM,WORM,MOD and other optical disk storage systems.
