Map
WeChat
Email alert
RSS1996 Vol. 20, No. 6
Display Method:
1996, 20(6): 321-323.
[Abstract]
[PDF 669KB]
Abstract:
Here we report a cross-mode-locked femtosecond Ti:sapphire laser which operates at the wavelengths of 804nm and 758nm and provides the synchronous pulse outputs with the duration of 25fs and 26fs simultaneously.The total average power of the pulse trains is 200mW.The laser uses the unsymmetrical "X" type resonator, and obtained higher operation stability.
Here we report a cross-mode-locked femtosecond Ti:sapphire laser which operates at the wavelengths of 804nm and 758nm and provides the synchronous pulse outputs with the duration of 25fs and 26fs simultaneously.The total average power of the pulse trains is 200mW.The laser uses the unsymmetrical "X" type resonator, and obtained higher operation stability.
1996, 20(6): 324-328.
Abstract:
In this paper,by means of Jones matrix calculus a system of four birefringence lenses and a polarizer used for spatial pulse shaping has been studied,including the intensity transmittance distribution and performance properties of the system.The parameter selection in practical design and the effect induced by fabrication error are discussed.The results show that the use of birefringence lenses is easy to change the transmittance function and suitable to get the spatial shaping of the line polarized Gaussian beam.
In this paper,by means of Jones matrix calculus a system of four birefringence lenses and a polarizer used for spatial pulse shaping has been studied,including the intensity transmittance distribution and performance properties of the system.The parameter selection in practical design and the effect induced by fabrication error are discussed.The results show that the use of birefringence lenses is easy to change the transmittance function and suitable to get the spatial shaping of the line polarized Gaussian beam.
1996, 20(6): 329-332.
Abstract:
In SLR(Satellite Laser Rangefinder),the laser plays the most important role in effecting the measurement range and accuracy of SLR system.The mode-locked laser,which has these advantages of narrow pulse,high power,higher stability,gets the wide application especially in SLR. This paper discusses the structure,performance and future application of mode-locked laser in SLR.
In SLR(Satellite Laser Rangefinder),the laser plays the most important role in effecting the measurement range and accuracy of SLR system.The mode-locked laser,which has these advantages of narrow pulse,high power,higher stability,gets the wide application especially in SLR. This paper discusses the structure,performance and future application of mode-locked laser in SLR.
1996, 20(6): 332-334.
Abstract:
A new technique of real time visualizing and quantitatively measuring of rocket exhausted plume field is presented in this paper.The beam source is a He-Ne laser and a alignment optical system to provide a parallel light beam 300mm in diameter. Then the parallel light beam goes through the plume field and two 20line/mm Ronchi gratings to obtain a diffraction pattern,and the pattern imaged at a CCD sensor to display on a monitor and been recorded.By means of image computer processing and Gladstone-Dale formula,with the parameters of grating index P,shift of more fringe,interval of more fringe,and interval of two gratings,the density distribution of the plume field can calculated.
A new technique of real time visualizing and quantitatively measuring of rocket exhausted plume field is presented in this paper.The beam source is a He-Ne laser and a alignment optical system to provide a parallel light beam 300mm in diameter. Then the parallel light beam goes through the plume field and two 20line/mm Ronchi gratings to obtain a diffraction pattern,and the pattern imaged at a CCD sensor to display on a monitor and been recorded.By means of image computer processing and Gladstone-Dale formula,with the parameters of grating index P,shift of more fringe,interval of more fringe,and interval of two gratings,the density distribution of the plume field can calculated.
1996, 20(6): 335-337.
Abstract:
By means of the optical microscope,scanning electron microscope and microhardness meter,the paper deals with the microstructure and property of a cost aluminum alloy after laser remelted treatment.The microstructure can be divided into remelted zone,transition layer and substrate.In the remelted zone,the width of dendritical pro eutectic α phase has been fined to 2～3μm from 20～40μm original state.Meanwhile the eutectic microstructure has also been broken up extremely.These changes make the microhardness of the treated surface be increased to 109～115μm from 67.4.
By means of the optical microscope,scanning electron microscope and microhardness meter,the paper deals with the microstructure and property of a cost aluminum alloy after laser remelted treatment.The microstructure can be divided into remelted zone,transition layer and substrate.In the remelted zone,the width of dendritical pro eutectic α phase has been fined to 2～3μm from 20～40μm original state.Meanwhile the eutectic microstructure has also been broken up extremely.These changes make the microhardness of the treated surface be increased to 109～115μm from 67.4.
1996, 20(6): 338-341.
Abstract:
Based on the relationship of the dispersion and absorption (gain) coefficient in laser classical theory, the dispersive characteristics of Ti:sapphire crystal has been discussed in this paper.According to the spectroscopy of Ti:sapphire,the abnormal dispersive curve(in absorption region) and normal dispersive curve(in normal region) are obtained. These results show that the refractive index variation of Ti:sapphire rised from the absorption and gain can be negligible and can be treated as normal dispersion.
Based on the relationship of the dispersion and absorption (gain) coefficient in laser classical theory, the dispersive characteristics of Ti:sapphire crystal has been discussed in this paper.According to the spectroscopy of Ti:sapphire,the abnormal dispersive curve(in absorption region) and normal dispersive curve(in normal region) are obtained. These results show that the refractive index variation of Ti:sapphire rised from the absorption and gain can be negligible and can be treated as normal dispersion.
1996, 20(6): 342-345.
Abstract:
The photoresist is used as recording materials to take the master of embossing hologram.This paper gives some illustration about embossing holograms and points out how to take good photoresist master including the choice of taking parameters with high diffraction efficiency and signal to noise ratio, the well distribution of illumination light, the reconstruction of inverse conjugate light, eliminating polarization, coherent length and the influence of external vibration.This paper also presents the higher power laser with good coherence is the key to gain good quality hologram.This paper is written by a lot of experiments and inspecting.
The photoresist is used as recording materials to take the master of embossing hologram.This paper gives some illustration about embossing holograms and points out how to take good photoresist master including the choice of taking parameters with high diffraction efficiency and signal to noise ratio, the well distribution of illumination light, the reconstruction of inverse conjugate light, eliminating polarization, coherent length and the influence of external vibration.This paper also presents the higher power laser with good coherence is the key to gain good quality hologram.This paper is written by a lot of experiments and inspecting.
1996, 20(6): 346-348.
Abstract:
This report describes a mini high repetition frequency TEA CO2 laser. The laser has following character such as TEM00 mode, divergence in far field≤4mrad,output energy 87.8mJ,FWHM=36.5ns,peak power0.96MW.The pulse repetition rate is about 130Hz(up to 255Hz).The laser can operate continuously at 50Hz for more than 1×107 shots.
This report describes a mini high repetition frequency TEA CO2 laser. The laser has following character such as TEM00 mode, divergence in far field≤4mrad,output energy 87.8mJ,FWHM=36.5ns,peak power0.96MW.The pulse repetition rate is about 130Hz(up to 255Hz).The laser can operate continuously at 50Hz for more than 1×107 shots.
1996, 20(6): 349-352.
Abstract:
A kind of design and manufacturing techniques for high-reflectance coatings of YAG lasers ellipsidal reflectors are introduced in this paper.The statistical global-extreme-value method and Powell conjugate direction method are used in optimizing design.Effect of dispersion and systemetical error are considered.Thus a practical and easily made high-reflectance coating system with simple construction is achieved.
A kind of design and manufacturing techniques for high-reflectance coatings of YAG lasers ellipsidal reflectors are introduced in this paper.The statistical global-extreme-value method and Powell conjugate direction method are used in optimizing design.Effect of dispersion and systemetical error are considered.Thus a practical and easily made high-reflectance coating system with simple construction is achieved.
1996, 20(6): 352-355.
Abstract:
According to a lot of experimental research to Cr,Tm,Ho:YAG laser operating at 2.1μm wavelength, the factors effecting on the output characteristics, such as cooling temperature, flashlamp pulse width,transparent index of output mirrors,are discussed.
According to a lot of experimental research to Cr,Tm,Ho:YAG laser operating at 2.1μm wavelength, the factors effecting on the output characteristics, such as cooling temperature, flashlamp pulse width,transparent index of output mirrors,are discussed.
1996, 20(6): 356-359.
Abstract:
This paper presents an optical method to detect the flaw of chain slice.The information of flaw is detected from the change of intensity distribution of diffuse reflection light from the round edge slice illuminated by a He-Ne laser and recorded with a CCD camera.The theoretical width and maximum deviation of diffuse reflection light are calculated and the position confined condition of CCD camera is given.The experimental results show that the device is simple in structure and easy to operate and able to select the shortcoming slices rapidly and automatically.
This paper presents an optical method to detect the flaw of chain slice.The information of flaw is detected from the change of intensity distribution of diffuse reflection light from the round edge slice illuminated by a He-Ne laser and recorded with a CCD camera.The theoretical width and maximum deviation of diffuse reflection light are calculated and the position confined condition of CCD camera is given.The experimental results show that the device is simple in structure and easy to operate and able to select the shortcoming slices rapidly and automatically.
1996, 20(6): 359-365.
Abstract:
In this paper,a newly developed science subject——light scattering and its application in measurement is introduced.The developmental history is reviewed.Based on Rayleigh scattering theory and Mie theory, the relationship between scattering and particle sizing, statistical characteristics of surface topography and micro defects in crystal are analyzed.At last,some typical application of scattering theory are presented.
In this paper,a newly developed science subject——light scattering and its application in measurement is introduced.The developmental history is reviewed.Based on Rayleigh scattering theory and Mie theory, the relationship between scattering and particle sizing, statistical characteristics of surface topography and micro defects in crystal are analyzed.At last,some typical application of scattering theory are presented.
1996, 20(6): 366-369.
Abstract:
This paper describes the characteristics and processing methods of laser cladding on aluminium alloys.The microstructure and mechanical properties in laser clad layers and interface are analyzed.The main problems and their renovated methods of laser cladding on aluminium alloys are pointed out.
This paper describes the characteristics and processing methods of laser cladding on aluminium alloys.The microstructure and mechanical properties in laser clad layers and interface are analyzed.The main problems and their renovated methods of laser cladding on aluminium alloys are pointed out.
1996, 20(6): 370-373.
Abstract:
Based on the transmission theory,the equations of the system sensitivity and the extinction value for laser rangefinder are derived and the verification tests are made.
Based on the transmission theory,the equations of the system sensitivity and the extinction value for laser rangefinder are derived and the verification tests are made.
1996, 20(6): 374-376.
Abstract:
Taking into account that the laser upper and lower levels have different level lifetimes and that the natural decay of the upper level will affect the population of the lower level,the author revi ses the quasi three level model developed by Fan et al. Although the derived predictions are similar to those by Fan mathematically,the revised model is more appropriate to describe the lasing process.The theoretical calculations have a good aggreement with the experimental results.
Taking into account that the laser upper and lower levels have different level lifetimes and that the natural decay of the upper level will affect the population of the lower level,the author revi ses the quasi three level model developed by Fan et al. Although the derived predictions are similar to those by Fan mathematically,the revised model is more appropriate to describe the lasing process.The theoretical calculations have a good aggreement with the experimental results.
1996, 20(6): 377-380.
Abstract:
The laser damage threshold of optical film and the accumulation effect of multi-pulsed laser damage to optical film at 532nm are summarized in this paper.In the experimental research,the various optical film are used to detect the damage threshold under the condition of single pulse or multi-pulse radiation.Meanwhile,the effect of laser pre-irradiation on damage threshold of the optical films are investigated.
The laser damage threshold of optical film and the accumulation effect of multi-pulsed laser damage to optical film at 532nm are summarized in this paper.In the experimental research,the various optical film are used to detect the damage threshold under the condition of single pulse or multi-pulse radiation.Meanwhile,the effect of laser pre-irradiation on damage threshold of the optical films are investigated.
1996, 20(6): 380-384.
Abstract:
The temperature distribution and deflection of a high power laser silicon mirror are predicted numerically by the finite difference method when its boundary is kept insulated.It is shown how the deflection of a mirror varies with laser power,optical spot diameter,mirror thickness and how its temperature distribution and deflection change with laser run time.
The temperature distribution and deflection of a high power laser silicon mirror are predicted numerically by the finite difference method when its boundary is kept insulated.It is shown how the deflection of a mirror varies with laser power,optical spot diameter,mirror thickness and how its temperature distribution and deflection change with laser run time.
