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RSS1999 Vol. 23, No. 3
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1999, 23(3): 129-131.
[Abstract]
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Abstract:
In a lidar receiver system,the optical interference filters are often used to eliminate the background signal.It is very important for the narrow band interference filter to match with the central wavelength of the Q switch double frequency laser,especially for the airborne laser bathymetrical system.In our experimental system,the interference filter is placed in emitting optical path.The intensity on output light is the integration of the product of the spectrum function of the filter and the emitting spectrum function of the laser.Adjusting the temperature of the filter,the central frequency of the filter can be moved to match the laser frequency,and to get maximum output signal.Based on the principle,the interference filter with central wavelength adjusting can be used in lidar receiver system to obtain the optimum receiving signal.
In a lidar receiver system,the optical interference filters are often used to eliminate the background signal.It is very important for the narrow band interference filter to match with the central wavelength of the Q switch double frequency laser,especially for the airborne laser bathymetrical system.In our experimental system,the interference filter is placed in emitting optical path.The intensity on output light is the integration of the product of the spectrum function of the filter and the emitting spectrum function of the laser.Adjusting the temperature of the filter,the central frequency of the filter can be moved to match the laser frequency,and to get maximum output signal.Based on the principle,the interference filter with central wavelength adjusting can be used in lidar receiver system to obtain the optimum receiving signal.
1999, 23(3): 132-133.
Abstract:
Some uniaxial crystals, such as KDP,DKDP, are usually used as Q-switch in laser technology. In practical application, the determination of the x(y) axis and the half wave voltage of uniaxial crystals can provide a great convenient for adjusted experiment of laser. In this paper, a rapid simple and convenient determination method of the x(y) axis and the half wave voltage of uniaxial crystals has been introduced.
Some uniaxial crystals, such as KDP,DKDP, are usually used as Q-switch in laser technology. In practical application, the determination of the x(y) axis and the half wave voltage of uniaxial crystals can provide a great convenient for adjusted experiment of laser. In this paper, a rapid simple and convenient determination method of the x(y) axis and the half wave voltage of uniaxial crystals has been introduced.
1999, 23(3): 134-137.
Abstract:
Etalon or Fabry Perot interferometer (FPI) based on multi beam interference principle can generate very narrow fringe and is sensitive to cavity length change. In this paper, three kinds of applications in length measurement of Etalon and FPI are reviewed: frequency locking and stabilization of lasers, precision positioning using optical multiplier and applications in nanometrology. The obstacle and the solutions in using FPI are also presented and the trend of FPI is given next. At last the possibility and importance of FPI in nanometrology is specially emphasized.
Etalon or Fabry Perot interferometer (FPI) based on multi beam interference principle can generate very narrow fringe and is sensitive to cavity length change. In this paper, three kinds of applications in length measurement of Etalon and FPI are reviewed: frequency locking and stabilization of lasers, precision positioning using optical multiplier and applications in nanometrology. The obstacle and the solutions in using FPI are also presented and the trend of FPI is given next. At last the possibility and importance of FPI in nanometrology is specially emphasized.
1999, 23(3): 138-141.
Abstract:
A magnetic pulse compressor(MPC) was used to provide proper pulse energy and rapid rise time of pulse for magnetic confined discharge circuit.This paper presents the design principle and circuit parameter selection of the magnetic switch,and gives the experimental results.
A magnetic pulse compressor(MPC) was used to provide proper pulse energy and rapid rise time of pulse for magnetic confined discharge circuit.This paper presents the design principle and circuit parameter selection of the magnetic switch,and gives the experimental results.
1999, 23(3): 142-145.
Abstract:
The crack of laser claded alloy also is a trouble thing in laser welding technique.In our study,we use the crackle density to indicate the crack susceptibility.It is shown that the Creq/Nieq composition has significant effect on the structure and the crack susceptibility of laser clad Fe-Cr-Ni coating.With the increasing of Creq/Nieq composition,the δ-Fe composition appears and becomes more and more,and the microstructure of the laser clad alloy changes.The crack susceptibility of the alloy is the lowest when Creq/Nieq composition is about 1.5 and δ-Fe composition is in the range of 5%～8%.
The crack of laser claded alloy also is a trouble thing in laser welding technique.In our study,we use the crackle density to indicate the crack susceptibility.It is shown that the Creq/Nieq composition has significant effect on the structure and the crack susceptibility of laser clad Fe-Cr-Ni coating.With the increasing of Creq/Nieq composition,the δ-Fe composition appears and becomes more and more,and the microstructure of the laser clad alloy changes.The crack susceptibility of the alloy is the lowest when Creq/Nieq composition is about 1.5 and δ-Fe composition is in the range of 5%～8%.
1999, 23(3): 145-148.
Abstract:
A magnetic pulse compressor(MPC) was used to improve performance of a circuit for magnetic confined discharges. Experiments with the MPC was presented.
A magnetic pulse compressor(MPC) was used to improve performance of a circuit for magnetic confined discharges. Experiments with the MPC was presented.
1999, 23(3): 149-153.
Abstract:
Using a 2kW CO2 laser to irradiate the mixture of Cu and Al (5% in weight fraction) powders on Q235 mild steel substrate the composite coatings of Fe/Cu has been successfully produced.The microstructure observations with SEM show that the spherical particles exist in the cladding layer and have regular distribution and are proved to be Fe rich phase particles.These particles have the important effect on the mechanical and electrical magnetic performances of the cladding layer.This paper points out that the formation procedure of the particles has the relation with the fogging process of metal and formulates an expression to calculate the diameter of the particles.
Using a 2kW CO2 laser to irradiate the mixture of Cu and Al (5% in weight fraction) powders on Q235 mild steel substrate the composite coatings of Fe/Cu has been successfully produced.The microstructure observations with SEM show that the spherical particles exist in the cladding layer and have regular distribution and are proved to be Fe rich phase particles.These particles have the important effect on the mechanical and electrical magnetic performances of the cladding layer.This paper points out that the formation procedure of the particles has the relation with the fogging process of metal and formulates an expression to calculate the diameter of the particles.
1999, 23(3): 153-155.
Abstract:
Using of transverse magnetic can improve discharge stability and increase the output power of the metal vapor lasers.In order to obtain shorter rising period of the discharge pulse,it is important to decrease the reactance of the discharge circuits.The analysis and calculation of the discharge circuit fit the experiment results very well.
Using of transverse magnetic can improve discharge stability and increase the output power of the metal vapor lasers.In order to obtain shorter rising period of the discharge pulse,it is important to decrease the reactance of the discharge circuits.The analysis and calculation of the discharge circuit fit the experiment results very well.
1999, 23(3): 156-158.
Abstract:
In this paper, we describe the design and function, application of the power unit controller for mini RF excited CO2 laser, pulse width modulation (PWM) is the convenient way to vary the laser average output power from 1% to 100% of maximum.
In this paper, we describe the design and function, application of the power unit controller for mini RF excited CO2 laser, pulse width modulation (PWM) is the convenient way to vary the laser average output power from 1% to 100% of maximum.
1999, 23(3): 159-161.
Abstract:
A short length room temperature sealed off CW CO laser has been described.It has an active medium length of 80cm,uses a gas mixture of He:N2:CO equals 73:35:1,cooled with running water at 10℃,laser transitions have been observed in ten rovibrational band,covering the spectral range from 5.0 to 6.0cm.The output is 0.2W.Especially with only half discharge,that means an active medium length of 40cm it could still give out 30mW laser output.
A short length room temperature sealed off CW CO laser has been described.It has an active medium length of 80cm,uses a gas mixture of He:N2:CO equals 73:35:1,cooled with running water at 10℃,laser transitions have been observed in ten rovibrational band,covering the spectral range from 5.0 to 6.0cm.The output is 0.2W.Especially with only half discharge,that means an active medium length of 40cm it could still give out 30mW laser output.
1999, 23(3): 162-165.
Abstract:
This paper describes a measurement method of statistical mean of the gas density and its fluctuation intensity in the turbulent field using a system composed of laser and PSD element and computer data collector.A mathematical model for experiment data processing was found based on an assuming that the flow field was axial symmetric and statistically stationary.And the quantity statistical mean characteristic inside the turbulent field can be obtained by using this technique described by this paper.
This paper describes a measurement method of statistical mean of the gas density and its fluctuation intensity in the turbulent field using a system composed of laser and PSD element and computer data collector.A mathematical model for experiment data processing was found based on an assuming that the flow field was axial symmetric and statistically stationary.And the quantity statistical mean characteristic inside the turbulent field can be obtained by using this technique described by this paper.
1999, 23(3): 165-167.
Abstract:
The two wave coupling is a fundamental and important photorefractive effect.Till now,many papers have studied the saturation effect of the gain coefficient of the photorefractive crystal.The studies found that the gain coefficient Gvaries with the increasing of the light intensity I,and goes through three stages:cut off,increasing and saturation regime.This paper formulated a set of experessions of materials parameters and presents the measuring principles of materials parameters of photorefractive crystal in intermediate regime,namely increasing regime.The experimental results are in accord with the theoretical analysis.
The two wave coupling is a fundamental and important photorefractive effect.Till now,many papers have studied the saturation effect of the gain coefficient of the photorefractive crystal.The studies found that the gain coefficient Gvaries with the increasing of the light intensity I,and goes through three stages:cut off,increasing and saturation regime.This paper formulated a set of experessions of materials parameters and presents the measuring principles of materials parameters of photorefractive crystal in intermediate regime,namely increasing regime.The experimental results are in accord with the theoretical analysis.
1999, 23(3): 172-175.
Abstract:
Temporal characteristics of the three pass Nd:phosphate glass slab amplifier system have been studied both theoretically and experimentally.Numerical calculations have been performed to simulate the discharge current pulse,passive Q-switched and amplified temporal laser pulse profiles.Our experiments have confiremed the numerical results.
Temporal characteristics of the three pass Nd:phosphate glass slab amplifier system have been studied both theoretically and experimentally.Numerical calculations have been performed to simulate the discharge current pulse,passive Q-switched and amplified temporal laser pulse profiles.Our experiments have confiremed the numerical results.
1999, 23(3): 176-179.
Abstract:
This paper reports CO2 laser point anesthesia used in 100 aged patients undergoing dental extraction.Before and after the dental extraction,self control observation was made on changes in pulse,respiration, blood pressure,and electrocardiogram to investigate effects of this anesthesia on their cardiovascular system.The mechanism of CO2 laser point anesthesia is also discussed.
This paper reports CO2 laser point anesthesia used in 100 aged patients undergoing dental extraction.Before and after the dental extraction,self control observation was made on changes in pulse,respiration, blood pressure,and electrocardiogram to investigate effects of this anesthesia on their cardiovascular system.The mechanism of CO2 laser point anesthesia is also discussed.
1999, 23(3): 180-182.
Abstract:
This paper introduced an optical setup to perform fractional Fourier transformation by Fresnel diffraction with a converging spherical wave illumination.In order to realize the arbitrary order fractional Fourier transformation,the diffraction distance q,the locations of point light source and lenses must satisfy the conditions,formulated by this paper.
This paper introduced an optical setup to perform fractional Fourier transformation by Fresnel diffraction with a converging spherical wave illumination.In order to realize the arbitrary order fractional Fourier transformation,the diffraction distance q,the locations of point light source and lenses must satisfy the conditions,formulated by this paper.
1999, 23(3): 183-185.
Abstract:
The tunable continuous ring dye laser is a useful laser source in nonlear optics,laser spectroscopy,photo chemistry and laser medicine.But the thermal lens effect and triplet are main problems to influence the applications.This paper introduces the cavity structure of the ring laser and the aberration compensation condition to provide the single mode operating.The experimental rasults show that proper COT added in EG solution can greatly improve the pumping efficiency.
The tunable continuous ring dye laser is a useful laser source in nonlear optics,laser spectroscopy,photo chemistry and laser medicine.But the thermal lens effect and triplet are main problems to influence the applications.This paper introduces the cavity structure of the ring laser and the aberration compensation condition to provide the single mode operating.The experimental rasults show that proper COT added in EG solution can greatly improve the pumping efficiency.
1999, 23(3): 186-188.
Abstract:
The nuclear polarized 129Xe gas by diode laser pumping was measured with a WP 80SY NMR spectrometer.We found that the SNR was greater than 100,and the signal enhancing factor was greater than 1000.After frozento solid state(80K),SNR was better than 50,the relaxation time was 4400s.
The nuclear polarized 129Xe gas by diode laser pumping was measured with a WP 80SY NMR spectrometer.We found that the SNR was greater than 100,and the signal enhancing factor was greater than 1000.After frozento solid state(80K),SNR was better than 50,the relaxation time was 4400s.
1999, 23(3): 189-190.
Abstract:
This paper reported the 416 cases treatments of perennial rhinitis with the Nd:YAG laser beam to illuminate the nervous ethmoidalis anterior septum,nervous nasal septum.The effective rate of 316 cases of vasomotor rhinitis and effective rate of perennials allergic rhinitis of 100 cases is up to 90% and 40%,respectively.
This paper reported the 416 cases treatments of perennial rhinitis with the Nd:YAG laser beam to illuminate the nervous ethmoidalis anterior septum,nervous nasal septum.The effective rate of 316 cases of vasomotor rhinitis and effective rate of perennials allergic rhinitis of 100 cases is up to 90% and 40%,respectively.
1999, 23(3): 190-193.
Abstract:
Laser induced wet etching into n Si in the dilute HF:H2O(1:20) by an Ar+ laser at room temperature is reported.Smooth etch features with Gaussian shape that depends on doping level of Si were observed.The laser etch rate is influenced by the incident power.For the HF/Si system,the etching is thought to take place photoelectrochemically with holes and electrons generated by the incident illumination of the laser beam.The result is explained reasonably by the mode of electrodless etching under the laser illumination in an electrochemical cell.
Laser induced wet etching into n Si in the dilute HF:H2O(1:20) by an Ar+ laser at room temperature is reported.Smooth etch features with Gaussian shape that depends on doping level of Si were observed.The laser etch rate is influenced by the incident power.For the HF/Si system,the etching is thought to take place photoelectrochemically with holes and electrons generated by the incident illumination of the laser beam.The result is explained reasonably by the mode of electrodless etching under the laser illumination in an electrochemical cell.
1999, 23(3): 168-172.
Abstract:
With the use of the theory of blazed phase gratings,the color separation phase grating used for ICF drivers is designed,which can off-axis separate the fundamental,2nd and 3rd harmonic waves.Theoretically,its diffraction efficiency for 0'th order at the 3rd harmonic wave is 100%.Experimentally,a color separation grating is made.Both its separation angles (at the 1st and 2nd harmonic waves) and its diffraction efficiencies for 0'th order are measured,and some significant results are presented.
With the use of the theory of blazed phase gratings,the color separation phase grating used for ICF drivers is designed,which can off-axis separate the fundamental,2nd and 3rd harmonic waves.Theoretically,its diffraction efficiency for 0'th order at the 3rd harmonic wave is 100%.Experimentally,a color separation grating is made.Both its separation angles (at the 1st and 2nd harmonic waves) and its diffraction efficiencies for 0'th order are measured,and some significant results are presented.
