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RSS2000 Vol. 24, No. 6
Display Method:
2000, 24(6): 337-341.
[Abstract]
[PDF 312KB]
Abstract:
The principle is presented and demonstrated of using a single He-Ne laser to sense displacement without nonlinear error in principle,and with function of self-calibration. By using frequency-splitting technology,we could separate a mode interval into four equal-width ranges with different intensity characteristics. One cavity mirror of the laser moves λ/8 along the laser axis when a laser frequency crosses one such range. The moving mirror contacts with and is moved by the object to be measured. Thus the He-Ne laser becomes a displacement sensor without using interference phenomenon which works with accuracy of 0.079μm,10mm measuring range,and function of distinguishing direction.
The principle is presented and demonstrated of using a single He-Ne laser to sense displacement without nonlinear error in principle,and with function of self-calibration. By using frequency-splitting technology,we could separate a mode interval into four equal-width ranges with different intensity characteristics. One cavity mirror of the laser moves λ/8 along the laser axis when a laser frequency crosses one such range. The moving mirror contacts with and is moved by the object to be measured. Thus the He-Ne laser becomes a displacement sensor without using interference phenomenon which works with accuracy of 0.079μm,10mm measuring range,and function of distinguishing direction.
2000, 24(6): 341-344.
Abstract:
The beam quality of a LD pumped Nd:YAG laser is measured with CCD camera system. The background characteristics of the CCD system and the influence of the size of integral box upon measurement results are investigated. The following conclusions can be derived form experimental results: (1) Background is strongly depend upon exposure time and pixel binning,while temperature has an ignorable effect upon it,whether with or without ambient light. (2) A 5%-cut is the minimum value in order to get a reasonable result.
The beam quality of a LD pumped Nd:YAG laser is measured with CCD camera system. The background characteristics of the CCD system and the influence of the size of integral box upon measurement results are investigated. The following conclusions can be derived form experimental results: (1) Background is strongly depend upon exposure time and pixel binning,while temperature has an ignorable effect upon it,whether with or without ambient light. (2) A 5%-cut is the minimum value in order to get a reasonable result.
2000, 24(6): 345-348.
Abstract:
The paper present an investigation on the characteristic of laser light transporting in human artery and vein with the aid of the primary theories of photo-biology,elementary medical science and physics. Diffuse reflectance R and transmittance T of human artery and vein samples is measured by a standard integrating spheres system,using He-Ne laser in 632.8nm wavelength and the absorbance A was deduced. The scattering phase function S(θ) is obtained by the experimental arrangement repacked from a spectroscope at angles from -90°to 90°for human artery and vein samples in 632.8nm wavelength and the mean cosines of scatter μ was calculated. The results show that the attenuation of the transmitted light intensity with sample thickness satisfy exponential attenuation by low power(P<20mW) laser radiation for human artery and vein and scattering of light in human artery and vein is highly converse peaked.
The paper present an investigation on the characteristic of laser light transporting in human artery and vein with the aid of the primary theories of photo-biology,elementary medical science and physics. Diffuse reflectance R and transmittance T of human artery and vein samples is measured by a standard integrating spheres system,using He-Ne laser in 632.8nm wavelength and the absorbance A was deduced. The scattering phase function S(θ) is obtained by the experimental arrangement repacked from a spectroscope at angles from -90°to 90°for human artery and vein samples in 632.8nm wavelength and the mean cosines of scatter μ was calculated. The results show that the attenuation of the transmitted light intensity with sample thickness satisfy exponential attenuation by low power(P<20mW) laser radiation for human artery and vein and scattering of light in human artery and vein is highly converse peaked.
2000, 24(6): 348-350.
Abstract:
Using the method of laser-induction vaporization,we got Al nanoparticles with F.C.C structure under different laser power. The relationships between laser power and the output or size of nanoparticles are discussed.
Using the method of laser-induction vaporization,we got Al nanoparticles with F.C.C structure under different laser power. The relationships between laser power and the output or size of nanoparticles are discussed.
2000, 24(6): 351-356.
Abstract:
Terahertz ray, one kind of electromagnetic radiation with ultrabroad bandwidth of spectrum, is generated by triggering a photoconductive emitter with femtosecond laser pulses; and it has many important scientific, industrial and military applications. Generation and detection of terahertz ray are analyzed, and several applications including THz-TDS (terahertz time-domain spectroscopy),two-dimensional electro-optic imaging of THz beams and THz ultra-wideband radar are also reviewed.
Terahertz ray, one kind of electromagnetic radiation with ultrabroad bandwidth of spectrum, is generated by triggering a photoconductive emitter with femtosecond laser pulses; and it has many important scientific, industrial and military applications. Generation and detection of terahertz ray are analyzed, and several applications including THz-TDS (terahertz time-domain spectroscopy),two-dimensional electro-optic imaging of THz beams and THz ultra-wideband radar are also reviewed.
2000, 24(6): 357-362.
Abstract:
In the paper the magnetically confined discharge technique is used to N2 laser．Experiments show that transverse magnetic field can increase N2 laser output,expand its operation atmosphere pressure range and increase its optimum atmosphere operation pressure.
In the paper the magnetically confined discharge technique is used to N2 laser．Experiments show that transverse magnetic field can increase N2 laser output,expand its operation atmosphere pressure range and increase its optimum atmosphere operation pressure.
2000, 24(6): 363-366.
Abstract:
This paper describes the experiments about optical fiber under white light and some homogenous light radiation.Experiments show that the transitivity of optical fiber rises under low radiation.At the same time some characteristics about the fiber's response to radiation in near infrared band are discovered.The experiment results are analyzed and some valuable conclusions are obtained.
This paper describes the experiments about optical fiber under white light and some homogenous light radiation.Experiments show that the transitivity of optical fiber rises under low radiation.At the same time some characteristics about the fiber's response to radiation in near infrared band are discovered.The experiment results are analyzed and some valuable conclusions are obtained.
2000, 24(6): 366-369.
Abstract:
In this paper some parameters of the plasma are measured by means of the acoustic waves produced by the interaction between high power laser and target materials．The test results are largely in accord with those from other methods.
In this paper some parameters of the plasma are measured by means of the acoustic waves produced by the interaction between high power laser and target materials．The test results are largely in accord with those from other methods.
2000, 24(6): 370-374.
Abstract:
A three dimensional quasi-state numerical model of fluid flow,heat transfer process in the melted pool for composite coating was developed,and the temperature profile,velocity profile in laser pool and pool geometry were successfully calculated. Affects of laser power on heat transfer and fluid flow in a laser pool and the pool geometry were investigated. Numerical results show that there is only one pool in the substrate when laser power is 750W,and there are two separated pools when laser power is 1400W for the composite coating system of Ti-Al(30%) alloy. It is decided by the thickness of the composite coating,whether the composite coating firstly is melt or Al substrate. The experiment of laser remelting was performed for composite coating system,the separated pools have been observed,and the pool geometry was agreement with that calculated.
A three dimensional quasi-state numerical model of fluid flow,heat transfer process in the melted pool for composite coating was developed,and the temperature profile,velocity profile in laser pool and pool geometry were successfully calculated. Affects of laser power on heat transfer and fluid flow in a laser pool and the pool geometry were investigated. Numerical results show that there is only one pool in the substrate when laser power is 750W,and there are two separated pools when laser power is 1400W for the composite coating system of Ti-Al(30%) alloy. It is decided by the thickness of the composite coating,whether the composite coating firstly is melt or Al substrate. The experiment of laser remelting was performed for composite coating system,the separated pools have been observed,and the pool geometry was agreement with that calculated.
2000, 24(6): 375-379.
Abstract:
By using the pulse-sequence model,the inverse problem of amplification of broad-spectral-bandwidth laser pulse has been studied,i.e.,to find the initial input temporal pulse profile,spatial profile,spectral distribution and fluence from the required output temporal,spatial pulse profile,spectral distribution and fluence as well as the given amplifier parameters. The results are useful for the design of high-power laser amplifiers.
By using the pulse-sequence model,the inverse problem of amplification of broad-spectral-bandwidth laser pulse has been studied,i.e.,to find the initial input temporal pulse profile,spatial profile,spectral distribution and fluence from the required output temporal,spatial pulse profile,spectral distribution and fluence as well as the given amplifier parameters. The results are useful for the design of high-power laser amplifiers.
2000, 24(6): 379-384.
Abstract:
A new nano-measurement system with laser, dual Fabry-Perot interferometers (DFPI), tapping stylus, flexure hinge stage and digital PID real-time computer control system is systematically designed. The theoretical basis of the nano-measurement system, using the measurement of amplitude difference or equal amplitude time interval of DFPI transmission wave, is proposed. The method of detection of tapping stylus vibration is theoretically analyzed. The finite element analysis method of small distance stage based on flexure hinge structure is proposed. The digital PID closed loop control system with the feedback signal of capacitance position sensor is applied, the system nonlinear influence caused by piezoelectricity element was solved. Finally, system error is analyzed.
A new nano-measurement system with laser, dual Fabry-Perot interferometers (DFPI), tapping stylus, flexure hinge stage and digital PID real-time computer control system is systematically designed. The theoretical basis of the nano-measurement system, using the measurement of amplitude difference or equal amplitude time interval of DFPI transmission wave, is proposed. The method of detection of tapping stylus vibration is theoretically analyzed. The finite element analysis method of small distance stage based on flexure hinge structure is proposed. The digital PID closed loop control system with the feedback signal of capacitance position sensor is applied, the system nonlinear influence caused by piezoelectricity element was solved. Finally, system error is analyzed.
2000, 24(6): 385-388.
Abstract:
In this paper,a mathematical model about the third order group-velocity dispersion is constructed,and it's theoretical solution is obtained.Two physical images are presented to interpret the relations between laser linewodth and wavelength in prism-mirror system and prism-grating system respectively.
In this paper,a mathematical model about the third order group-velocity dispersion is constructed,and it's theoretical solution is obtained.Two physical images are presented to interpret the relations between laser linewodth and wavelength in prism-mirror system and prism-grating system respectively.
2000, 24(6): 388-391.
Abstract:
If laser fast remelt technique is used to prepare CuCr50 surface,a 3～5μm fine-grained layer will generate．The layer has less porosity．The hardness of the surface increases nearly one time than that of the matrix and the conductivity changes little．The thickness of the fine-grained layer can be controlled by laser power while the other operation parameters don't change．There is a heat-influenced layer between the fine-grained layer and the matrix,whose properties is between theirs too．Experiments show that laser fast remelt is useful to increase the hardness of CuCr50 contact material.
If laser fast remelt technique is used to prepare CuCr50 surface,a 3～5μm fine-grained layer will generate．The layer has less porosity．The hardness of the surface increases nearly one time than that of the matrix and the conductivity changes little．The thickness of the fine-grained layer can be controlled by laser power while the other operation parameters don't change．There is a heat-influenced layer between the fine-grained layer and the matrix,whose properties is between theirs too．Experiments show that laser fast remelt is useful to increase the hardness of CuCr50 contact material.
2000, 24(6): 392-396.
Abstract:
The importance of study on submillimeter wave(SMMW) is introduced.The applications of SMMW laser on basic disciplines,astronomy,physics,medicine,biology,military affairs,communication,engineering etc are reviewed and forecasted.
The importance of study on submillimeter wave(SMMW) is introduced.The applications of SMMW laser on basic disciplines,astronomy,physics,medicine,biology,military affairs,communication,engineering etc are reviewed and forecasted.
2000, 24(6): 396-401.
Abstract:
Based on Frunhofer-diffraction, the diffraction intensities of lognormal distribution particles is numerically culculated in this paper. It is displayed in figures as a function of diffraction angle for the different number-size and wight-size distribution parameters. Influnce of the dispersity and medium particle diameter on the central intensity of diffraction pattern and production, the number, and the position angle of diffraction fringe are introduced by comparing and analysing.
Based on Frunhofer-diffraction, the diffraction intensities of lognormal distribution particles is numerically culculated in this paper. It is displayed in figures as a function of diffraction angle for the different number-size and wight-size distribution parameters. Influnce of the dispersity and medium particle diameter on the central intensity of diffraction pattern and production, the number, and the position angle of diffraction fringe are introduced by comparing and analysing.
2000, 24(6): 402-405.
Abstract:
Two-wave coupling and four-wave mixing phase conjugation properties of Ce-doped KNSBN crystal are investigated at 632.8nm as the temperature increases from 30℃ to 95℃.Two-wave coupling experiment shows that both two-beam coupling gain coefficient Γ and the response speed of the crystal can be enhanced by several times when the temperature is elevated to 95℃.The four-wave mixing phase conjugation reflectivity increases from 4% to 14% in this temperature range.
Two-wave coupling and four-wave mixing phase conjugation properties of Ce-doped KNSBN crystal are investigated at 632.8nm as the temperature increases from 30℃ to 95℃.Two-wave coupling experiment shows that both two-beam coupling gain coefficient Γ and the response speed of the crystal can be enhanced by several times when the temperature is elevated to 95℃.The four-wave mixing phase conjugation reflectivity increases from 4% to 14% in this temperature range.
2000, 24(6): 405-408.
Abstract:
This paper describes a laser beam quality analyzer based on CCD, computer and MATLAB. The detailed composition, basic function and characteristics of the software are presented.
This paper describes a laser beam quality analyzer based on CCD, computer and MATLAB. The detailed composition, basic function and characteristics of the software are presented.
