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RSS2005 Vol. 29, No. 3
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2005, 29(3): 225-227,232.
[Abstract]
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Abstract:
An easy and accurate method of system calibrating the 3-D optical multi-sensor profilometry with line structured-illuminated laser was proposed.This method can efficiently and fast carry out the transformation between CCD pixel coordinate and world coordinate while required only one measurement for the special model.Furthermore,it avoids the multifarious survey of the system parameters.As proved by experiments,the present method can effectively restrain the influence of speckle to the laser triangular measurement system and obtain calibration accuracy of about 0.05mm within 100mm depth range.
An easy and accurate method of system calibrating the 3-D optical multi-sensor profilometry with line structured-illuminated laser was proposed.This method can efficiently and fast carry out the transformation between CCD pixel coordinate and world coordinate while required only one measurement for the special model.Furthermore,it avoids the multifarious survey of the system parameters.As proved by experiments,the present method can effectively restrain the influence of speckle to the laser triangular measurement system and obtain calibration accuracy of about 0.05mm within 100mm depth range.
2005, 29(3): 228-232.
Abstract:
The effects of vibration on the intersatellite optical communications were analyzed,and the reasons and characters of vibration of the satellite platform were summarized.A vibration compensation system was designed for low frequency vibration,and the compensation experiment for the low frequency vibration was carried through.The result shows that the vibration compensati on system is feasible and effective.
The effects of vibration on the intersatellite optical communications were analyzed,and the reasons and characters of vibration of the satellite platform were summarized.A vibration compensation system was designed for low frequency vibration,and the compensation experiment for the low frequency vibration was carried through.The result shows that the vibration compensati on system is feasible and effective.
2005, 29(3): 233-236.
Abstract:
The measurement model of wave-plate's phase retardation based on the theory of compensate was introduced with the help of common Jones formula of wave-plate,a novel method was proposed to measu re the phase retardation for many kinds of wave-plates whose axes were unknown. The stepping motor was used to drive the wave-plate and a grating encoder was used to measure rotating angle of the analyzer.A light intensity meter was used to gather the energy of laser.While the measured wave-plate was rotated around,the phase retardation was obtained from the maximum and minimum value.This method is rapid and convenient.
The measurement model of wave-plate's phase retardation based on the theory of compensate was introduced with the help of common Jones formula of wave-plate,a novel method was proposed to measu re the phase retardation for many kinds of wave-plates whose axes were unknown. The stepping motor was used to drive the wave-plate and a grating encoder was used to measure rotating angle of the analyzer.A light intensity meter was used to gather the energy of laser.While the measured wave-plate was rotated around,the phase retardation was obtained from the maximum and minimum value.This method is rapid and convenient.
2005, 29(3): 237-240.
Abstract:
To improve the performance of FBG interrogation system,a novel fiber Bragg grating sensor interrogation system based on a tunable fiber Fabry-Perot (FFP) filter was demonstrated.Firstly,a reference fiber Bragg grating (FBG) was used as a wavelength reference element.By measuring the wavelength difference between reference FBG and sensor FBG,the drift of tunable FFP filter's cavity length was compensated.Secondly,a quadratic fit function wa s made with software based on experiment results.This function showed a good fit to the relationship between the displacement of PZT and control voltage.It was used to calculate the wavelength of the sensing FBG.In experiment,a strain of 0~1800 με was applied to the sensing FBG and the maximum nonlinearity deviat ion of measured wavelength was 0.5%.Experiment results show that the measured er ror caused by the drift of FFP filter's cavity length and PZT's nonlinearity is greatly reduced and a higher accuracy is obtained.
To improve the performance of FBG interrogation system,a novel fiber Bragg grating sensor interrogation system based on a tunable fiber Fabry-Perot (FFP) filter was demonstrated.Firstly,a reference fiber Bragg grating (FBG) was used as a wavelength reference element.By measuring the wavelength difference between reference FBG and sensor FBG,the drift of tunable FFP filter's cavity length was compensated.Secondly,a quadratic fit function wa s made with software based on experiment results.This function showed a good fit to the relationship between the displacement of PZT and control voltage.It was used to calculate the wavelength of the sensing FBG.In experiment,a strain of 0~1800 με was applied to the sensing FBG and the maximum nonlinearity deviat ion of measured wavelength was 0.5%.Experiment results show that the measured er ror caused by the drift of FFP filter's cavity length and PZT's nonlinearity is greatly reduced and a higher accuracy is obtained.
2005, 29(3): 241-243.
Abstract:
The goal of this article is to present a measuring system,which is appropriate to industry measuring and science research,for relative intensity noise (RIN) of semiconductor lasers.The advantage of the system is simple and flexible.The RINs of some semiconductor lasers (with different cavity length,with or without coating)were measured.Special attention was paid to the effect of coating on the RIN.It is found that the quality stability of the lasers will be improved and the RIN character will be more sensible to feedback with coating than the lasers without coating.The reflectivity of coating should be chosen carefully according to the real application conditions,and the reflection of the front facet coating should not be too small.
The goal of this article is to present a measuring system,which is appropriate to industry measuring and science research,for relative intensity noise (RIN) of semiconductor lasers.The advantage of the system is simple and flexible.The RINs of some semiconductor lasers (with different cavity length,with or without coating)were measured.Special attention was paid to the effect of coating on the RIN.It is found that the quality stability of the lasers will be improved and the RIN character will be more sensible to feedback with coating than the lasers without coating.The reflectivity of coating should be chosen carefully according to the real application conditions,and the reflection of the front facet coating should not be too small.
2005, 29(3): 244-247.
Abstract:
Based on the basic theory of artificial neural network,BP network model is founded to predict the highest surface temperature and bending angle in the process of laser sheet metal bending.Experimental result and numerical simulation result verified by experiment are used to train BP network by means of MATLAB software.Sample data regularity of nonlinear is curve fitting through BP network so as to optimize technological parameters and provide effective foundation for actual production.
Based on the basic theory of artificial neural network,BP network model is founded to predict the highest surface temperature and bending angle in the process of laser sheet metal bending.Experimental result and numerical simulation result verified by experiment are used to train BP network by means of MATLAB software.Sample data regularity of nonlinear is curve fitting through BP network so as to optimize technological parameters and provide effective foundation for actual production.
2005, 29(3): 248-250.
Abstract:
In order to discuss the effects of group delay dispersion (GDD) and self-phase modulation (SPM) on the pulses generated from passively mode-locking solid-state laser,the Haus master equation which described the femtosecond pulse solid laser dynamics was solved numerically.Adopting the fast saturable absorber model,the pulse evolutions were analyzed in two conditions,one of which was the balance between GDD and SPM,and the other was the effect of GDD and SPM together.The conclusion shows shorter and steadier pulse can be produced by solid-state laser in the latter condition.
In order to discuss the effects of group delay dispersion (GDD) and self-phase modulation (SPM) on the pulses generated from passively mode-locking solid-state laser,the Haus master equation which described the femtosecond pulse solid laser dynamics was solved numerically.Adopting the fast saturable absorber model,the pulse evolutions were analyzed in two conditions,one of which was the balance between GDD and SPM,and the other was the effect of GDD and SPM together.The conclusion shows shorter and steadier pulse can be produced by solid-state laser in the latter condition.
2005, 29(3): 251-254.
Abstract:
The process of laser cutting thick metal plates was in troduced.The main problems and their causes were analyzed.A series of newly deve loped thick cutting methods were ultimately recommended with respect to improvements on lasers,focusing system and assisted gasjet,which provides the technique references for further research and industrial application.
The process of laser cutting thick metal plates was in troduced.The main problems and their causes were analyzed.A series of newly deve loped thick cutting methods were ultimately recommended with respect to improvements on lasers,focusing system and assisted gasjet,which provides the technique references for further research and industrial application.
2005, 29(3): 255-257,260.
Abstract:
The aim is to study the effect of Nd:YAG laser inhibiting caries progression in enamel.After surface treatment,48 enamel blocks were divided six groups of eight blocks per group:0.01W,0.3W,0.8W,1W,1.4W laser irradiation groups and control group.Enamel blocks after laser irradiation and control group were put into 5mL of lactate buffer solution (0.1mol/L),which were put in water of 37℃ for 72h.The hardness and morphology of enamel surface were investigated by microhardness meter and scanning electron microscopy.Compa red with the control group,the group with 0.3W laser treatment had the least caries lesion (p0.01).Finally,the mechanism of caries prevention by laser is discussed.With laser parameters being controlled suitably,the best caries inhibition can be achieved when the temperature rising of enamel surface is in the range of 300℃~400℃.
The aim is to study the effect of Nd:YAG laser inhibiting caries progression in enamel.After surface treatment,48 enamel blocks were divided six groups of eight blocks per group:0.01W,0.3W,0.8W,1W,1.4W laser irradiation groups and control group.Enamel blocks after laser irradiation and control group were put into 5mL of lactate buffer solution (0.1mol/L),which were put in water of 37℃ for 72h.The hardness and morphology of enamel surface were investigated by microhardness meter and scanning electron microscopy.Compa red with the control group,the group with 0.3W laser treatment had the least caries lesion (p0.01).Finally,the mechanism of caries prevention by laser is discussed.With laser parameters being controlled suitably,the best caries inhibition can be achieved when the temperature rising of enamel surface is in the range of 300℃~400℃.
2005, 29(3): 258-260.
Abstract:
To suppress 1064nm line and 1338nm line,utilizing the dichroic mirror technology,a Nd:YAG quasi-CW laser operating at the single wavelength of 1318.8nm was developed.The output power of 122W was obta ined at a pump power of 2100W with the total efficiency of 5.8%,and the slope efficiency of 8.22%.The unstability of output power was less than (±5%.)The threshold power was about 500W.The 1318.8nm Nd:YAG laser with simple construction can work stably,which is of great value to laser therapy and nation al defence.
To suppress 1064nm line and 1338nm line,utilizing the dichroic mirror technology,a Nd:YAG quasi-CW laser operating at the single wavelength of 1318.8nm was developed.The output power of 122W was obta ined at a pump power of 2100W with the total efficiency of 5.8%,and the slope efficiency of 8.22%.The unstability of output power was less than (±5%.)The threshold power was about 500W.The 1318.8nm Nd:YAG laser with simple construction can work stably,which is of great value to laser therapy and nation al defence.
2005, 29(3): 261-265.
Abstract:
Using the theoretical model of pulsed beam through gra ting pair in the case of finite beam size and starting from the Fourier angle spectrum of the pulsed beam,the spatial and temporal properties of the pulsed super-Gaussian beam single and double passing compressor and the effects of high-order dispersion are studied.It's found that when the pulsed super-Gaussian beam once passes through the grating pair,the time-dependent spatial shift will be introduced in the output pulse by the transverse spectrum shift,but the effect will be eliminated when twice passes and that high-order dispersion affects the spatial and temporal properties of the output pulse,causes the pulse front distortion and induces space-time aberration in the output pulse.
Using the theoretical model of pulsed beam through gra ting pair in the case of finite beam size and starting from the Fourier angle spectrum of the pulsed beam,the spatial and temporal properties of the pulsed super-Gaussian beam single and double passing compressor and the effects of high-order dispersion are studied.It's found that when the pulsed super-Gaussian beam once passes through the grating pair,the time-dependent spatial shift will be introduced in the output pulse by the transverse spectrum shift,but the effect will be eliminated when twice passes and that high-order dispersion affects the spatial and temporal properties of the output pulse,causes the pulse front distortion and induces space-time aberration in the output pulse.
2005, 29(3): 266-269.
Abstract:
Currently,light detecting and ranging (LIDAR) systems are widely used in underwater object-detecting,ocean remote sensing,etc.However,the seawater and suspended granules do affect the transmission of laser,and restrict the application scope of LIDAR.The studies before almost aim at the reducing of backscattered component.However,the study on fore-scattered component bar ely appeared on literatures.The temporal and frequency characteristics of fore-scattered component of laser were studied and the theory about how to enhance the system SNR was presented.
Currently,light detecting and ranging (LIDAR) systems are widely used in underwater object-detecting,ocean remote sensing,etc.However,the seawater and suspended granules do affect the transmission of laser,and restrict the application scope of LIDAR.The studies before almost aim at the reducing of backscattered component.However,the study on fore-scattered component bar ely appeared on literatures.The temporal and frequency characteristics of fore-scattered component of laser were studied and the theory about how to enhance the system SNR was presented.
2005, 29(3): 270-274.
Abstract:
The advantages and contents of surface quality of laser sheets cutting and its affecting factors,its research advances were reviewed.Deeper mechanism research of surface quality on laser sheets cutting,especially investigation of dynamic behavior,on-line monitoring and control and 3-D cutting will be emphasized in the near future.
The advantages and contents of surface quality of laser sheets cutting and its affecting factors,its research advances were reviewed.Deeper mechanism research of surface quality on laser sheets cutting,especially investigation of dynamic behavior,on-line monitoring and control and 3-D cutting will be emphasized in the near future.
2005, 29(3): 275-277.
Abstract:
Based on the dispersion-compensation fiber (DCF),the dispersion-shift fiber (DSF) and erbium-doped nonlinear amplifying fiber loop mirror (ED-NALM),a novel designed model of the optical pulse compression to the chirped pulse generated from gain-switched distributed feedback (GS-DFB) se miconductor laser was presented.The numerical simulations reveal that a chirped optical pulse with 30ps full-width in half maximum generated from GS-DFB semic onductor laser can be compressed to a pedestal-free pulse with 180fs full-width.
Based on the dispersion-compensation fiber (DCF),the dispersion-shift fiber (DSF) and erbium-doped nonlinear amplifying fiber loop mirror (ED-NALM),a novel designed model of the optical pulse compression to the chirped pulse generated from gain-switched distributed feedback (GS-DFB) se miconductor laser was presented.The numerical simulations reveal that a chirped optical pulse with 30ps full-width in half maximum generated from GS-DFB semic onductor laser can be compressed to a pedestal-free pulse with 180fs full-width.
2005, 29(3): 278-280,283.
Abstract:
A wavelet multi-resolution analytical method (WMRA) was used to analyze those echosignals.By the measure,for those signals with S/N above 1.2,the noise can be eliminated,and effective signals can be picked up.When applying the WMRA to a TEA CO2 DIAL lidar,a satisfying result was obtained.When using this method,the ability of laser radar can be greatly improved.
A wavelet multi-resolution analytical method (WMRA) was used to analyze those echosignals.By the measure,for those signals with S/N above 1.2,the noise can be eliminated,and effective signals can be picked up.When applying the WMRA to a TEA CO2 DIAL lidar,a satisfying result was obtained.When using this method,the ability of laser radar can be greatly improved.
2005, 29(3): 281-283.
Abstract:
Based on coupling-wave equations,a new formula about the mode discrimination of two-segment DFB lasers was obtained after applying the mean-field method.The mode characteristics and the wavelength tuning charact eristics were analyzed with the formula.The calculating results accord with the experimental data,which shows the effectivity of this formula to study the different modes of DFB lasers.
Based on coupling-wave equations,a new formula about the mode discrimination of two-segment DFB lasers was obtained after applying the mean-field method.The mode characteristics and the wavelength tuning charact eristics were analyzed with the formula.The calculating results accord with the experimental data,which shows the effectivity of this formula to study the different modes of DFB lasers.
2005, 29(3): 284-286.
Abstract:
To assess the performance of a semiconductor laser,knowledge of gain and loss at a known pumping level is essential.Both the gain and the loss coefficients were obtained through analyzing amplified spontaneous emission (ASE) measured with variable stripe length (VSL) method,and serious gain saturation phenomenon was observed in the process.The results confirm the feasibility of the VSL method in studying the performance of GaNLD samples.Performance of LDs with two different structures in gain and gain saturation were compared through VSL method,and the reason that leads to the differen ce was discussed.
To assess the performance of a semiconductor laser,knowledge of gain and loss at a known pumping level is essential.Both the gain and the loss coefficients were obtained through analyzing amplified spontaneous emission (ASE) measured with variable stripe length (VSL) method,and serious gain saturation phenomenon was observed in the process.The results confirm the feasibility of the VSL method in studying the performance of GaNLD samples.Performance of LDs with two different structures in gain and gain saturation were compared through VSL method,and the reason that leads to the differen ce was discussed.
2005, 29(3): 287-290,314.
Abstract:
By means of the finite element method the laser-gener ated ultrasonic wave is simulated when laser interacts on the Al surface.After the resuts are computed for the Al plates with the same thickness but different depths of surface-breaking cracks and a given depth of subsuface crak under the top surface of the Al plate,the characteristics of the reflected wave and transmitted wave generated by the Rayleigh waves interacted with the surface breaking cracds and the subsurface crack are attained.Furthermore,based on Wingner-Vile theory the spectrum of the two signals recorded on both sides of the crack are a nalyzed.The result shows that the depths of the surface cracks and the subsurface crack cause the obvious effect on the spectral characteristics.This phenomena could be useful to the laser ultrasonic quantitative non-destructive evaluation (QNDE).
By means of the finite element method the laser-gener ated ultrasonic wave is simulated when laser interacts on the Al surface.After the resuts are computed for the Al plates with the same thickness but different depths of surface-breaking cracks and a given depth of subsuface crak under the top surface of the Al plate,the characteristics of the reflected wave and transmitted wave generated by the Rayleigh waves interacted with the surface breaking cracds and the subsurface crack are attained.Furthermore,based on Wingner-Vile theory the spectrum of the two signals recorded on both sides of the crack are a nalyzed.The result shows that the depths of the surface cracks and the subsurface crack cause the obvious effect on the spectral characteristics.This phenomena could be useful to the laser ultrasonic quantitative non-destructive evaluation (QNDE).
2005, 29(3): 291-294,310.
Abstract:
The development,research level and developed trend of LD pumped Q-switched Erglass laser are introduced.The following aspects are included:erbium glass laser meterial,Q-switched technology and pumped system.High iondopant concentration is the development trend of erbium glass.Both-sides-symmetry-pump can improve efficiency and reduce glass meterial's ther mal aberration.Co2+:MgAIO4 crystal has recently become the more popular passive Q-switched meterial.Precision temperature control is needed when the laser operates at high repeat frequency.Finally,some questiones to be solved for its further development are discussed.
The development,research level and developed trend of LD pumped Q-switched Erglass laser are introduced.The following aspects are included:erbium glass laser meterial,Q-switched technology and pumped system.High iondopant concentration is the development trend of erbium glass.Both-sides-symmetry-pump can improve efficiency and reduce glass meterial's ther mal aberration.Co2+:MgAIO4 crystal has recently become the more popular passive Q-switched meterial.Precision temperature control is needed when the laser operates at high repeat frequency.Finally,some questiones to be solved for its further development are discussed.
2005, 29(3): 295-296,303.
Abstract:
A new optical encryption technique based on computer-generated hologram of asymmetry fractional Fourier transform is presented.In this method,the fractional Fourier transform hologram of original object with diff erent orders on axis x and y was coded and ploted into computer-generated hologram.In order to reconstruct the encoded image,special fractional Fourier transform systems with certain orders were needed.Because of its particularity of image reconstruction,it was regarded as a new optical security system and could be used in anti-counterfeiting.Computer simulated results show that this met hod can greatly improve the quality of security and anti-counterfeiting,at the same time practical application is more convenient compared to conventional encr yption technique,hence it has wide application and prospect.
A new optical encryption technique based on computer-generated hologram of asymmetry fractional Fourier transform is presented.In this method,the fractional Fourier transform hologram of original object with diff erent orders on axis x and y was coded and ploted into computer-generated hologram.In order to reconstruct the encoded image,special fractional Fourier transform systems with certain orders were needed.Because of its particularity of image reconstruction,it was regarded as a new optical security system and could be used in anti-counterfeiting.Computer simulated results show that this met hod can greatly improve the quality of security and anti-counterfeiting,at the same time practical application is more convenient compared to conventional encr yption technique,hence it has wide application and prospect.
2005, 29(3): 297-300.
Abstract:
The analytical expression for the temperature rise of a passive optical component under the irradiation of multiple short pulses with different amplitudes and intervals has been derived from the Fourier heat transfer equation.Calculations and analyses have been made for the case that the radiation is a train of periodically repeated pulses.The relations between the distribution of temperature rise and such factors as the number of pulses,pulse intervals,pulse flux densities have been discussed.Finally the phase distortion induced by the temperature rise has been estimated.
The analytical expression for the temperature rise of a passive optical component under the irradiation of multiple short pulses with different amplitudes and intervals has been derived from the Fourier heat transfer equation.Calculations and analyses have been made for the case that the radiation is a train of periodically repeated pulses.The relations between the distribution of temperature rise and such factors as the number of pulses,pulse intervals,pulse flux densities have been discussed.Finally the phase distortion induced by the temperature rise has been estimated.
2005, 29(3): 301-303.
Abstract:
The measurement principle of the time-of-flight technique is described.The effects of excitation light wavelength,pulse energy,pulse width and circuit time constant,et al. on the carrier mobility are studied. The results indicate that choosing appropriate measuring parameters,the experimental results could be achieved quickly,exactly and reliably.
The measurement principle of the time-of-flight technique is described.The effects of excitation light wavelength,pulse energy,pulse width and circuit time constant,et al. on the carrier mobility are studied. The results indicate that choosing appropriate measuring parameters,the experimental results could be achieved quickly,exactly and reliably.
2005, 29(3): 304-307.
Abstract:
The research of material processing with femtosecond laser has been performed in many countries.The development of many kinds of material processing with femtosecond laser in the world is introduced and the optical parameters'effect on the micromahining process is analyzed.
The research of material processing with femtosecond laser has been performed in many countries.The development of many kinds of material processing with femtosecond laser in the world is introduced and the optical parameters'effect on the micromahining process is analyzed.
2005, 29(3): 308-310.
Abstract:
To display the effect of mirror misalignment on beam distributions more intuitively,Fox-Liiterative diffraction calculation method was used to solve the Fresnel integral equation and three-dimension figures of effected beam were presented.The results indicate the beam in both near and far field will be aberrated and simultaneously the beam quality will be deteriorated when misalignment appears.
To display the effect of mirror misalignment on beam distributions more intuitively,Fox-Liiterative diffraction calculation method was used to solve the Fresnel integral equation and three-dimension figures of effected beam were presented.The results indicate the beam in both near and far field will be aberrated and simultaneously the beam quality will be deteriorated when misalignment appears.
2005, 29(3): 311-314.
Abstract:
In order to find high-quality stimulated Brillouin scattering (SBS) mediums,experiments have been performed on several full halogenated hydrocarbon liquid mediums.SBS parameters,including gain coefficient,phonon lifetime and absorption coefficient,are measured or calculated.The medium tetrachloroethylene (C2Cl4) has a gain coefficient of 9.0cm·GW-1,phonon lifetime 0.59ns and absorption coefficient 0.003cm-1.The influence of chemical construction on SBS characteristics is also discussed.
In order to find high-quality stimulated Brillouin scattering (SBS) mediums,experiments have been performed on several full halogenated hydrocarbon liquid mediums.SBS parameters,including gain coefficient,phonon lifetime and absorption coefficient,are measured or calculated.The medium tetrachloroethylene (C2Cl4) has a gain coefficient of 9.0cm·GW-1,phonon lifetime 0.59ns and absorption coefficient 0.003cm-1.The influence of chemical construction on SBS characteristics is also discussed.
2005, 29(3): 315-317,321.
Abstract:
After deriving self-phase modulation (SPM) and cross-phase modulation(XPM), under the joint effect of phase modulation frequency chirp (PMC),the relationship between PMC and initial chirp,is numerically studied,the transmission effects of dispersion managed soliton (DMS) in the transmission system are calculated when there is initial chirp 40Gbit/s return-to-ze ro(RZ) or not.The second-order and third-order dispersion is completely compen sated(the average dispersion being zero).The result indicates that when the input power is fixed,the effect of initial chirp C on PMC determines the effect and transmission performance of polarization-divided multiplexing soliton tech nique in the system and that choosing properly the value C can effectively restrain polarization modes dispersion(PMD) and lengthen the distance of stability transmission of soliton pulse.
After deriving self-phase modulation (SPM) and cross-phase modulation(XPM), under the joint effect of phase modulation frequency chirp (PMC),the relationship between PMC and initial chirp,is numerically studied,the transmission effects of dispersion managed soliton (DMS) in the transmission system are calculated when there is initial chirp 40Gbit/s return-to-ze ro(RZ) or not.The second-order and third-order dispersion is completely compen sated(the average dispersion being zero).The result indicates that when the input power is fixed,the effect of initial chirp C on PMC determines the effect and transmission performance of polarization-divided multiplexing soliton tech nique in the system and that choosing properly the value C can effectively restrain polarization modes dispersion(PMD) and lengthen the distance of stability transmission of soliton pulse.
2005, 29(3): 318-321.
Abstract:
The effects of atmospheric scales on aperture averaging of Gaussian-Schell beam propagating in an atmospheric turbulence were examined by means of a modulation spectrum for the index of refraction fluctuations including the outer-and-inner scales of the atmospheric turbulence and the approx imation of across-spectral density function for the coherent function.An easily evaluated expression valid in the weak fluctuation regime for aperture-averag ing factor including the effects of the turbulent outer-scale was obtained.The results show that with the outer-scale reducing,the aperture averaging of scintillations for Gaussian-Schell beam propagating in an atmospheric turbulence will reduce.The effect of the outer-scale of turbulence on the aperture averaging of scintillations for incoherence beam can be ignored.
The effects of atmospheric scales on aperture averaging of Gaussian-Schell beam propagating in an atmospheric turbulence were examined by means of a modulation spectrum for the index of refraction fluctuations including the outer-and-inner scales of the atmospheric turbulence and the approx imation of across-spectral density function for the coherent function.An easily evaluated expression valid in the weak fluctuation regime for aperture-averag ing factor including the effects of the turbulent outer-scale was obtained.The results show that with the outer-scale reducing,the aperture averaging of scintillations for Gaussian-Schell beam propagating in an atmospheric turbulence will reduce.The effect of the outer-scale of turbulence on the aperture averaging of scintillations for incoherence beam can be ignored.
2005, 29(3): 322-324.
Abstract:
Development of laser systems for simultaneous measurement of multi-demensional errors is a trend in the machine tool metrology and in dustry application.Several methods for simultaneously measuring five-demensional information were surveyed and discussed,some ideas about its trend were given.
Development of laser systems for simultaneous measurement of multi-demensional errors is a trend in the machine tool metrology and in dustry application.Several methods for simultaneously measuring five-demensional information were surveyed and discussed,some ideas about its trend were given.
2005, 29(3): 325-327,331.
Abstract:
On the foundation of frustrated total internal reflect ion (FTIR) light modulator,combining the character of surface plasma wave (SPW) which is excitated on the surface of metal and can be resonant with ppolari zation light and absorbs its energy,a modified type SPW light modulator of Otto structure is designed.In Otto structure,the reflectivity can be modulated by changing thickness of air gap or the angle of incidence.The numerical simulation is made in the situation of three kinds of metal:Cu,Al,Ag and two wavelengths:1.06 4μm,0.532μm,and the results show that modulate effect of the method of changi ng angle of incidence is better,0.5°of the angle change can result in reflectivity's variety value is above 0.9.
On the foundation of frustrated total internal reflect ion (FTIR) light modulator,combining the character of surface plasma wave (SPW) which is excitated on the surface of metal and can be resonant with ppolari zation light and absorbs its energy,a modified type SPW light modulator of Otto structure is designed.In Otto structure,the reflectivity can be modulated by changing thickness of air gap or the angle of incidence.The numerical simulation is made in the situation of three kinds of metal:Cu,Al,Ag and two wavelengths:1.06 4μm,0.532μm,and the results show that modulate effect of the method of changi ng angle of incidence is better,0.5°of the angle change can result in reflectivity's variety value is above 0.9.
2005, 29(3): 328-331.
Abstract:
In accordance with the strict demand on the laser beam direction at high power solid-state lasers,the angle drift is measured at sub-laser in XG-Ⅱ.The micron quantity microscope is used in the experiment.The internal and external cause which bring about the angle drift are considered at the process of analysis,the data is analysed and handled at root-mean-square.The result is that the angle drift of sub-laser in XG-Ⅱ is 1.55″±0.72″,it a ttains the design objective of being smaller than 2″ and contents with the requirement of shooting practice.
In accordance with the strict demand on the laser beam direction at high power solid-state lasers,the angle drift is measured at sub-laser in XG-Ⅱ.The micron quantity microscope is used in the experiment.The internal and external cause which bring about the angle drift are considered at the process of analysis,the data is analysed and handled at root-mean-square.The result is that the angle drift of sub-laser in XG-Ⅱ is 1.55″±0.72″,it a ttains the design objective of being smaller than 2″ and contents with the requirement of shooting practice.
2005, 29(3): 332-333,336.
Abstract:
Preperation parameters are studied to get highly pure vanadium dioxide thin films.VO2 thin films are deposited by magnetron sputtering methods.VO2 thin films prepared in different conditions are studied by means of X-ray photoelectron spectroscopy (XPS), constituents of the VO3+,VO4+ and VO5+ in the film are gotten by fitting the XPS peaks with 100% Guassian like curves.Then the thin films are annealed to increase the percentages of the VO4+, the effect of annealing is analyzed.The transmittance at 10.6 μm changed from 74% at 60℃ to 11.93% at 74℃, semiconductor-to-metal phase transition occurs.
Preperation parameters are studied to get highly pure vanadium dioxide thin films.VO2 thin films are deposited by magnetron sputtering methods.VO2 thin films prepared in different conditions are studied by means of X-ray photoelectron spectroscopy (XPS), constituents of the VO3+,VO4+ and VO5+ in the film are gotten by fitting the XPS peaks with 100% Guassian like curves.Then the thin films are annealed to increase the percentages of the VO4+, the effect of annealing is analyzed.The transmittance at 10.6 μm changed from 74% at 60℃ to 11.93% at 74℃, semiconductor-to-metal phase transition occurs.
2005, 29(3): 334-336.
Abstract:
Using the thin lens approximation and imaging formulation,the relations between the first-order ghost image and the focal length of all kinds of lenses are derived,which provides guidance for the design of lens in the high power laser facility.
Using the thin lens approximation and imaging formulation,the relations between the first-order ghost image and the focal length of all kinds of lenses are derived,which provides guidance for the design of lens in the high power laser facility.
