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RSS1998 Vol. 22, No. 5
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1998, 22(5): 257-261.
[Abstract]
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Abstract:
In terms of graphical analysis method,the effective reflectivity of antireflection film deposited on the facet of semiconductor laser diode has been studied.The results show,if the spectral width of reflective curve of the antireflective film is finite,the reflectivity is generally greater than the minimum of reflectivity curve.It is possible to minimize the effective reflectivity through carefully choosing the wavelength at which the reflectivity curve reaches its minimum.
In terms of graphical analysis method,the effective reflectivity of antireflection film deposited on the facet of semiconductor laser diode has been studied.The results show,if the spectral width of reflective curve of the antireflective film is finite,the reflectivity is generally greater than the minimum of reflectivity curve.It is possible to minimize the effective reflectivity through carefully choosing the wavelength at which the reflectivity curve reaches its minimum.
1998, 22(5): 261-264.
Abstract:
A phosphate Nd:glass Brewster angled slab oscillator and multipass amplifier system has been built up,where a novel three pass amplifier with two prisms has been proposed and a Cr4+:YAG colour center crystal has been used as the passive Q-switcher.In our experiment the output with high beam quality of Mx2=1.49 and My2=1.57 and with an energy gain of 23 has been achived.The experimental data have been compared with the numerical calculation results,showing a good consistency.
A phosphate Nd:glass Brewster angled slab oscillator and multipass amplifier system has been built up,where a novel three pass amplifier with two prisms has been proposed and a Cr4+:YAG colour center crystal has been used as the passive Q-switcher.In our experiment the output with high beam quality of Mx2=1.49 and My2=1.57 and with an energy gain of 23 has been achived.The experimental data have been compared with the numerical calculation results,showing a good consistency.
1998, 22(5): 265-267.
Abstract:
A kind of polarization maintaining fiber ring resonator used in fiber ring resonator sensor for angular velocity measurement is reported in this paper.The measurement principle is based on Sagnac effect.So the system is composed of a laser with narrow spectra,fiber resonator,detector and other control circuits.According to the numerical calculation and experimental results,several important optical parameters,which have influence on the performance of system,are analyzed and optimized.Now the fiber ring resonator has been adopted in the sensor system.
A kind of polarization maintaining fiber ring resonator used in fiber ring resonator sensor for angular velocity measurement is reported in this paper.The measurement principle is based on Sagnac effect.So the system is composed of a laser with narrow spectra,fiber resonator,detector and other control circuits.According to the numerical calculation and experimental results,several important optical parameters,which have influence on the performance of system,are analyzed and optimized.Now the fiber ring resonator has been adopted in the sensor system.
1998, 22(5): 268-270.
Abstract:
The physics mechanism of field effect and thermal effect on a variable refractivity optical dielectric thin film consisted of nonquarter wavelength film layers irradiated by a beam of high power laser to produce damage have been discussed in this paper,and laser damage thresholds of film layer specimen have been measured.It has been indicated theoretically and experimentally that the thin film absorbing laser energy is a main reason to produce laser damage for this kind of film.
The physics mechanism of field effect and thermal effect on a variable refractivity optical dielectric thin film consisted of nonquarter wavelength film layers irradiated by a beam of high power laser to produce damage have been discussed in this paper,and laser damage thresholds of film layer specimen have been measured.It has been indicated theoretically and experimentally that the thin film absorbing laser energy is a main reason to produce laser damage for this kind of film.
1998, 22(5): 271-272.
Abstract:
In this paper,we proposed a new method to design a Nd:YAG laser operating at 1.3188μm single wavelength and TEM00 mode.To construct the laser,we employed a aperture and especially coated films to restrain 1.3200μm spectrum and exit 1.3188μm oscillation spectrum.The satisfactory results were obtained through the experiments.
In this paper,we proposed a new method to design a Nd:YAG laser operating at 1.3188μm single wavelength and TEM00 mode.To construct the laser,we employed a aperture and especially coated films to restrain 1.3200μm spectrum and exit 1.3188μm oscillation spectrum.The satisfactory results were obtained through the experiments.
1998, 22(5): 273-276.
Abstract:
This article proposes the three major factors influencing the welded seam strength of laser welded diamond saw:(1)selecting proper and well weldable substrate materials;(2)selecting sintering procedure parameters,such as sintering temperature of 650℃～750℃,synthetic pressure of 20 MPa,temperature holding time of 4 min;(3)selecting welding parameters,such as welding power 1kW,welding speed 1m/min,shift amount.0.1～0.25mm.
This article proposes the three major factors influencing the welded seam strength of laser welded diamond saw:(1)selecting proper and well weldable substrate materials;(2)selecting sintering procedure parameters,such as sintering temperature of 650℃～750℃,synthetic pressure of 20 MPa,temperature holding time of 4 min;(3)selecting welding parameters,such as welding power 1kW,welding speed 1m/min,shift amount.0.1～0.25mm.
1998, 22(5): 276-279.
Abstract:
By using different types of resonators with different VRMs for the Nd:glass slab laser,the experiments have been performed and the output beam quality has been compared.A comparison with plane concave resonator has been made too.The diagnostic system has been tested and verified,the measurement results are correct,the results obtained in this paper would be useful for the application of VRM to the slab laser.
By using different types of resonators with different VRMs for the Nd:glass slab laser,the experiments have been performed and the output beam quality has been compared.A comparison with plane concave resonator has been made too.The diagnostic system has been tested and verified,the measurement results are correct,the results obtained in this paper would be useful for the application of VRM to the slab laser.
1998, 22(5): 280-283.
Abstract:
Considering V2O5 as a gas-sensing materials,we successfully manufactured 2 dimensional V2O5 film by Sol-Gel method.The gas-sensing reflective spectra in ammonia,alcohol,acetone and butane vapor are experimentally studied.The experiments show that the film has good gas selectivity and monotonicity of the response curve in whole visible spectrum to ammonia.So the film can be used in optical fiber gas sensing head.
Considering V2O5 as a gas-sensing materials,we successfully manufactured 2 dimensional V2O5 film by Sol-Gel method.The gas-sensing reflective spectra in ammonia,alcohol,acetone and butane vapor are experimentally studied.The experiments show that the film has good gas selectivity and monotonicity of the response curve in whole visible spectrum to ammonia.So the film can be used in optical fiber gas sensing head.
1998, 22(5): 284-287.
Abstract:
Optical matrix of multirod laser resonator with difference in rod thermal lensing is used in considering the dynamic mode matching characteristics of active elements.By analyzing the relation between the defined normalized mode matching factor and the varying resonator parameters,we derived a relation for adjusting the resonator parameters of two rod system which result in a fine mode matching.Experimental results show in accordance with theoretical analysis and for two rod system we get the stable output power between 0W～530W.
Optical matrix of multirod laser resonator with difference in rod thermal lensing is used in considering the dynamic mode matching characteristics of active elements.By analyzing the relation between the defined normalized mode matching factor and the varying resonator parameters,we derived a relation for adjusting the resonator parameters of two rod system which result in a fine mode matching.Experimental results show in accordance with theoretical analysis and for two rod system we get the stable output power between 0W～530W.
1998, 22(5): 287-289.
Abstract:
Using Fourier transfer,we extend the transparent index function of step grating into Fourier series and derived the expression of diffraction efficiency.The expression shows that the diffraction efficiency is the function of width ratio ξ,height ratio γ and wavelength ratio σ.As a example,we give the calculation results of diffraction efficiency of 2-level step grating.
Using Fourier transfer,we extend the transparent index function of step grating into Fourier series and derived the expression of diffraction efficiency.The expression shows that the diffraction efficiency is the function of width ratio ξ,height ratio γ and wavelength ratio σ.As a example,we give the calculation results of diffraction efficiency of 2-level step grating.
1998, 22(5): 290-294.
Abstract:
In this paper,after putting forward the principle of LSST in detecting micro bulk defects in silicon and some simulating results of various size of defects scattering distributions,a novel analyzing way called character recognition is developed.This paper presents the first character defined according to wave number of the laser scattering distribution,and the second character defined according to the unsymmetry of scattering optical intensity.By using the character Ⅰ,the quantity scale of bulk defects can be obtained first,and then with character Ⅱ the detailed quantity scale less than 1μm can be gained if the character Ⅰ is 1.The method has the advantages of analyzing defects size quickly and making it possible to implement automation of detecting system,etc.It is worth being used in practice.
In this paper,after putting forward the principle of LSST in detecting micro bulk defects in silicon and some simulating results of various size of defects scattering distributions,a novel analyzing way called character recognition is developed.This paper presents the first character defined according to wave number of the laser scattering distribution,and the second character defined according to the unsymmetry of scattering optical intensity.By using the character Ⅰ,the quantity scale of bulk defects can be obtained first,and then with character Ⅱ the detailed quantity scale less than 1μm can be gained if the character Ⅰ is 1.The method has the advantages of analyzing defects size quickly and making it possible to implement automation of detecting system,etc.It is worth being used in practice.
1998, 22(5): 294-297.
Abstract:
By simulating multiple modes and uneven energy distribution of actual light beams,the relationship between PSD localization and above mentioned uneven energy distribution is established in this paper,and thus,theoretically and experimentally justifies that PSD localization is solely subject to the balance center of light beam spots.
By simulating multiple modes and uneven energy distribution of actual light beams,the relationship between PSD localization and above mentioned uneven energy distribution is established in this paper,and thus,theoretically and experimentally justifies that PSD localization is solely subject to the balance center of light beam spots.
1998, 22(5): 298-300.
Abstract:
In this paper,it is first reported that the optical parametric oscillator(OPO),which is pumped by the back amplified output of stimulated Brillouin scattering(SBS) in the Nd:YAG laser system,is utilized as a preferable light source of the laser rangefinder(1.57μm).The most output energy of the OPO is 21.6mJ,and the corresponding transmitting efficiency is 32%.The experiment results agree well with the theory analysis.
In this paper,it is first reported that the optical parametric oscillator(OPO),which is pumped by the back amplified output of stimulated Brillouin scattering(SBS) in the Nd:YAG laser system,is utilized as a preferable light source of the laser rangefinder(1.57μm).The most output energy of the OPO is 21.6mJ,and the corresponding transmitting efficiency is 32%.The experiment results agree well with the theory analysis.
1998, 22(5): 300-302.
Abstract:
This paper analyses the reasons of laser trough in laser carving.We propose three compensative algorithms,called vector filling algorithm,square filling and parallel movement algorithm,based on computer graphics.All the algorithms are proved to be well in practice.
This paper analyses the reasons of laser trough in laser carving.We propose three compensative algorithms,called vector filling algorithm,square filling and parallel movement algorithm,based on computer graphics.All the algorithms are proved to be well in practice.
1998, 22(5): 303-308.
Abstract:
The neighborhood related processing technique that we have studied for several years is used to design a laser warning device to provide much higher target angle allocation accuracy than conventional spectrum distinguishing photodiode array warning device.If neighboring two laser photodiodes detected out the laser signal,the comparison logic will judge in which direction the laser radiate at the accuracy of 5°.Experimental results show that the technique is worth practicing.
The neighborhood related processing technique that we have studied for several years is used to design a laser warning device to provide much higher target angle allocation accuracy than conventional spectrum distinguishing photodiode array warning device.If neighboring two laser photodiodes detected out the laser signal,the comparison logic will judge in which direction the laser radiate at the accuracy of 5°.Experimental results show that the technique is worth practicing.
1998, 22(5): 309-312.
Abstract:
Being a catalyst,gold sited directly in capillary of sealed-off CO2 laser can make CO2 effectively recompose that disassociated with the discharge,but cause change of the performance status of device yet.This paper investigated the electric field distribution,available volume of plasma and exciting efficiency,drift current,ambipolar diffusion,the neutralization of the charges on the wall in capillary,especially the wall-current,performed further contrasting test with ring film and separate film plated by means of the plating technology ourselvse and non-catalyst devices,founded their mathematical model and made program to simulate numerally,pointed out that the conducting ring film result in the efficiency decline and change or going so far as to worsen the characteristic of laser performance,definitely advanced the new concepts and relevant device design about separate and disperse film catalyst and confirmed their superiority,and,modified the conclusion of previous work,i.e.,both the breakdown voltage and the terminal voltage were increasing in the gold-ring tube.
Being a catalyst,gold sited directly in capillary of sealed-off CO2 laser can make CO2 effectively recompose that disassociated with the discharge,but cause change of the performance status of device yet.This paper investigated the electric field distribution,available volume of plasma and exciting efficiency,drift current,ambipolar diffusion,the neutralization of the charges on the wall in capillary,especially the wall-current,performed further contrasting test with ring film and separate film plated by means of the plating technology ourselvse and non-catalyst devices,founded their mathematical model and made program to simulate numerally,pointed out that the conducting ring film result in the efficiency decline and change or going so far as to worsen the characteristic of laser performance,definitely advanced the new concepts and relevant device design about separate and disperse film catalyst and confirmed their superiority,and,modified the conclusion of previous work,i.e.,both the breakdown voltage and the terminal voltage were increasing in the gold-ring tube.
1998, 22(5): 313-317.
Abstract:
Based on the analysis of coupling action of temperature,phase transformation and stress,the phase transformation condition and equation related to materials properties are discussed.The expression showing the temperature field effecting on phase transformation and the thermal elastoplastic constitutive equation are derived.Finally,the analyses of temperature field and stress field are made by finite element method.
Based on the analysis of coupling action of temperature,phase transformation and stress,the phase transformation condition and equation related to materials properties are discussed.The expression showing the temperature field effecting on phase transformation and the thermal elastoplastic constitutive equation are derived.Finally,the analyses of temperature field and stress field are made by finite element method.
1998, 22(5): 318-320.
Abstract:
An optical electrical technology method to assess dental pulp vitality is introduced.May be,it is difficult to construct an effective optical probe for middle aged or older patients.In these cases,vascularity in gingiva is much greater than in pulp,the signal resulting from gingiva could be larger.This paper recommends to use photoplethysmography technology,pulse oximeter or laser Doppler flowmeter.
An optical electrical technology method to assess dental pulp vitality is introduced.May be,it is difficult to construct an effective optical probe for middle aged or older patients.In these cases,vascularity in gingiva is much greater than in pulp,the signal resulting from gingiva could be larger.This paper recommends to use photoplethysmography technology,pulse oximeter or laser Doppler flowmeter.
