Journals >Chinese Journal of Lasers
Contents
2004
Volume: 31 Issue 6
29 Article(s)
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Research Article
Study on Properties of Cerium-Doped Silica Glass Tube for Xenon Flash Lamp
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
In this paper, the absorption spectra and mechanical strength of Ce-doped silica glasses with different concentrations are studied. Several kinds of Ce-doped silica glass tubes with different impurity (such as CeO2, Al2O3, TiO2) are made, and high-power xenon flashlamp are made by these tubes with same procedures. The In this paper, the absorption spectra and mechanical strength of Ce-doped silica glasses with different concentrations are studied. Several kinds of Ce-doped silica glass tubes with different impurity (such as CeO2, Al2O3, TiO2) are made, and high-power xenon flashlamp are made by these tubes with same procedures. The spectral, mechanical strength and thermal properties of the Ce-doped silica glass tubes are measured and the explosion energy of xenon flashlamps are also tested. By comparative experiments it is found that silica glass doped with proper amounts of CeO2 can strongly absorb ultraviolet radiation of xenon plasma at 320 nm and improve the radiation spectra of xenon flashlamps. But because dopping CeO2 in silica glass reduces mechanical strength of silica glass tubes, the explosion energy of xenon flashlamps made of Ce-doped silica glass tubes is lower than that of silica glass tubes xenon flashlamp, and the life time of flashlamp is decreased. So it is necessary to develop new materials which can not only absorb ultraviolet radiation of xenon plasma at 320 nm but also have excellent mechanical strength..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 654 (2004)
Micro-Cavity Filter Based on MEMS Micro-Fabrication Technology
[in Chinese], [in Chinese], and [in Chinese]
A novel fabrication technique is designed to obtain silicon crystalline flat planes. The selected silicon crystalline planes 〈110〉 are pre-obtained by deep-RIE, then EPW wet etch is used to remove the roughness after deep-RIE. Through the two etching process, a silicon mold with smooth sidewall can be got. The proposedA novel fabrication technique is designed to obtain silicon crystalline flat planes. The selected silicon crystalline planes 〈110〉 are pre-obtained by deep-RIE, then EPW wet etch is used to remove the roughness after deep-RIE. Through the two etching process, a silicon mold with smooth sidewall can be got. The proposed technique is demonstrated by fabricating a solid polymer dye micro-cavity laser type filter that is replicated by the silicon mold. The experiment of simple filter confirm that the micro-cavity can work well in a filter..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 659 (2004)
Optimizational Design Scheme for Three-in-One Composite Achromatic λ/4 Wave-Plate
[in Chinese], [in Chinese], and [in Chinese]
The achromatic wave-plates are widely used in communication, biology, geological, aviation and ocean because their retardation are not vary with wavelength unlike the common ones. This article gives the designed theory for the identical material three-in-one composite achromatic λ/4 wave-plate according to composite waThe achromatic wave-plates are widely used in communication, biology, geological, aviation and ocean because their retardation are not vary with wavelength unlike the common ones. This article gives the designed theory for the identical material three-in-one composite achromatic λ/4 wave-plate according to composite wave-plate theory, generalizes the theoretical curve between retardation and wavelength, then a optimum design scheme is put forward based on flat-plate three-in-one composite achromatic wave-plate in response to theoretical curve of retardation. Theory analysis shows that this design can improve achromatic range from 130 to 140 nm which is longer than common ones under the same delay deviation, and advances its achromatic accuracy by adjusting composite angle exactly for specific operating requirements..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 662 (2004)
Two-Step Ion-Exchanged Waveguides Splitter with Low-Loss
[in Chinese], and [in Chinese]
A detailed experiment and a theoretical analysis of two-step ion-exchanged glass optical power splitter are reported. In order to facilitate quantitative analysis, a rational model of physics for a rise inverse sine structure of 1×2 S-branch power splitter in glass is proposed. In thermal ion exchange, the distribA detailed experiment and a theoretical analysis of two-step ion-exchanged glass optical power splitter are reported. In order to facilitate quantitative analysis, a rational model of physics for a rise inverse sine structure of 1×2 S-branch power splitter in glass is proposed. In thermal ion exchange, the distribution of normalized refractive index of two-step ion-exchanged optical power splitter and the distribution of splitter refractive index of different exchange time have been gotten. On this basis, these surface half-round channel waveguides are fabricated by first performing a thermal Tl+ exchange in melt Tl2SO4 through a mask patterned on the glass surface. The resulting surface channel waveguides are then buried by second thermal Na+ exchange, unmasked ion exchange, in melt NaNO3. In this step the Tl+ ions migrate from the glass, and the wavguides are buried below the glass surface. A optical power splitter of insertion loss 0.15 dB and coupling ratio 50∶50 has been realized..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 665 (2004)
Effect of Irradiation on Ti-Doped Sapphire by Excimer Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Ti-doped sapphire crystals were irradiated by the argon fluoride (ArF) excimer laser. Comparing the spectra before and after irradiation, the increasing of absorption spectrum peak at 218 nm is much larger than that at 193 nm and 266 nm. Fluorescence spectra of different figure of merit (FOM) samples at 420 nm were meaTi-doped sapphire crystals were irradiated by the argon fluoride (ArF) excimer laser. Comparing the spectra before and after irradiation, the increasing of absorption spectrum peak at 218 nm is much larger than that at 193 nm and 266 nm. Fluorescence spectra of different figure of merit (FOM) samples at 420 nm were measured, and the results indicated that fluorescence intensity decreased with increasing the FOM. The fluorescence intensity of samples at 420 nm decreased after the excimer laser irradiation. In the EPR spectrum of the Ti-doped sapphire, the intensity of the Ti3+ signal increased after the irradiation. All results indicated that Ti4+ ions changed to Ti3+ ions during the irradiation of the excimer laser..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 669 (2004)
A Kind of Compact Design on Cube Corner Retro-Reflector Array in Laser Cooperative Target on Satellite
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The laser retroreflectors as a laser cooperative target on satellite are traditionally arranged in circle array. 38 hexagon retro reflectors, each with the effective incident aperture of 30 mm and the height of 25 mm, are designed, thus a light and high stable cooperative target with the size of 280 mm×160 mm and The laser retroreflectors as a laser cooperative target on satellite are traditionally arranged in circle array. 38 hexagon retro reflectors, each with the effective incident aperture of 30 mm and the height of 25 mm, are designed, thus a light and high stable cooperative target with the size of 280 mm×160 mm and the weight less than 2 kg is obtained. After numerical simulation, a single retroreflector demands the integrated dihedral angle error of 5°±0.5″, considering velocity aberration compensation. So an angle error of each dihedral of ～1″ is introduced deliberately. Such a design increases the machining difficulty of the array floor. But comparing with a traditional design, computation results shows the new compact one decreases 15.5% of the weight, and increases 10.3% of both the effective reflection coefficient and the echo photons at the same dimension..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 673 (2004)
Numerical Simulation and Analysis on Photonic Crystal Fibers with Closing to Zero and Flattened Chromatic Dispersion
[in Chinese], [in Chinese], and [in Chinese]
Basing on scalar approximation the dispersion property of photonic crystal fibers (PCF) with lower air filling fraction are investigated by an effective index approach in this paper. It is found that the dispersion property of PCF can be modulated effectively by changing the pitch and the air hole size in PCF cladding.Basing on scalar approximation the dispersion property of photonic crystal fibers (PCF) with lower air filling fraction are investigated by an effective index approach in this paper. It is found that the dispersion property of PCF can be modulated effectively by changing the pitch and the air hole size in PCF cladding. PCF can be designed not only with less than 1.27 μm zero-dispersion wavelength but also with two zero-dispersion wavelengths at the wavelength of optical communication. PCF with closing to zero and flattened chromatic dispersion in wavelength division multiplexing waveband of optical communication can also be obtained. The designed PCF has absolute value less than 2.0 ps·km-1·nm-1 in dispersion coefficient D and absolute value less than 0.02 ps·km-1·nm-2 in dispersion slope D′ at the wavelengths from 1.2 μm to 1.7 μm..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 713 (2004)
Multi-Probe Fiber-Optic Evanescent Wave Biosensor and Its Characterization
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A multi-probe fiber-optic evanescent wave biosensor has been developed based on the principle of evanescent wave while light propagates along optical fiber. A laser diode at 635 nm wavelength is used as the light source. The biosensor can interrogate five individual fibers at one time. Thus assays for five separate anaA multi-probe fiber-optic evanescent wave biosensor has been developed based on the principle of evanescent wave while light propagates along optical fiber. A laser diode at 635 nm wavelength is used as the light source. The biosensor can interrogate five individual fibers at one time. Thus assays for five separate analytes can be conducted on the same sample. For all the five fibers, sensitivity limit of 0.01 nmol/L is obtained from the detection of Cy5 serial solutions with various concentrations. The response curves of five fibers have good consistency, the relative standard deviation is less than 10%. All the results are comparable with those that are obtained by a commercial biochip scanner. Real-time fluorescence of human IgG binding to goat anti-body IgG antibody immobilized on fiber core has been successfully detected..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 718 (2004)
Study on Photonic Crystal Fibers by Effective-Index Model
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The propagation properties of photonic crystal fibers (PCF) are discussed with effective-index model. The effective-index model of photonic crystal fiber was introduced at first. By solving the scalar wave equation within cladding of PCF, the effective index of the cladding was calculated. Applying theory of standard fThe propagation properties of photonic crystal fibers (PCF) are discussed with effective-index model. The effective-index model of photonic crystal fiber was introduced at first. By solving the scalar wave equation within cladding of PCF, the effective index of the cladding was calculated. Applying theory of standard fiber, we may calculate the propagation properties of PCF as a step-index fiber. With this model, the effective index of PCF cladding with different structure parameters was discussed. The refractive index difference of the core and cladding increases as the wavelength increases, and the endlessly single-mode behaviour was illuminated. The mode refractive index and the waveguide dispersion of the fundamental mode in PCF was calculated. It is shown that the relationship between waveguide dispersion and the air hole pitch is in accord with the scaling properties of Maxwell equations, the waveguide dispersion is also critically dependant on the size of the air hole. These analyses indicated that PCF is a promising component for enhanced control of dispersion in optical communication system..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 723 (2004)
Holography and Information Processing
Computer-Generated Holographic Phase Shifter with Liquid Crystal Display
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Exact phase shifts are very important for phase-shifting digital holography or interferometry. Some phase-shifting methods suitable for different applications have been proposed; but most of them often require precise moving or rotating drivers. A new digital phase shifter with liquid crystal display (LCD) is proposed Exact phase shifts are very important for phase-shifting digital holography or interferometry. Some phase-shifting methods suitable for different applications have been proposed; but most of them often require precise moving or rotating drivers. A new digital phase shifter with liquid crystal display (LCD) is proposed in this paper. In this method, the phase shifts needed in digital holography are induced by changing encodes of the computer-generated holograms (CGH) displayed on the LCD. The advantage of this method is that the phase shifts can be controlled digitally and no any precise mechanical moving or rotating element is required. Both the theoretical analysis and experimental results demonstrate the feasibility of this approach. The phase stability of the LCD as a phase shifter is studied experimentally. The experiments showed that the range of the phase fluctuates is below about 0.036 rad..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 693 (2004)
Laser Devices and Laser Physics
Intelligent System for Selecting Laser Cutting Parameters
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
In laser cutting, many factors influence cutting quality. In this paper an intelligent system has been developed in order that the cutting parameters can be created quantitatively. This system is different from database and normal expert system. It combines factor experiment method and artificial neural network (ANN). In laser cutting, many factors influence cutting quality. In this paper an intelligent system has been developed in order that the cutting parameters can be created quantitatively. This system is different from database and normal expert system. It combines factor experiment method and artificial neural network (ANN). Only a few tests are required to obtain basic data and then the test results are input into the ANN system. After the ANN is trained and learns from the test results, the system can produce laser cutting knowledge and optimized parameters. Based on test data and knowledge the cutting parameters given by the system will be more accuracy and reliable. Finally the intelligent system is applied to select 3D position laser cutting parameters. It shows the system being very effective and useful..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 575 (2004)
Laser Manufacturing
Laser Quenching+Nitriding Compound Treatment of 38CrMoAlA Steels
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Laser quenching, nitriding, nitriding-laser quenching compound treatment and laser quenching-nitriding compound treatment on 38CrMoAlA steels are carried out, and theirs depth of hardening layers and their surface hardness are investigated. The experimental results show that the laser quenching -nitriding compound treaLaser quenching, nitriding, nitriding-laser quenching compound treatment and laser quenching-nitriding compound treatment on 38CrMoAlA steels are carried out, and theirs depth of hardening layers and their surface hardness are investigated. The experimental results show that the laser quenching -nitriding compound treatment may raise surface hardness by 100Hv than by using nitriding only and the depth of hardening layers is not increased; that the laser quenching may raise the depth of hardening layers of previous nitriding in the nitriding-laser quenching compound treatment and the surface hardness drops; the depth of hardening layers and the surface hardness in the nitriding-laser quenching compound treatment are shallower and higher than the laser quenching, respectively..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 761 (2004)
Microstructure Character of Aluminium Alloy Coating with Nd∶YAG Pulsed Laser SiC Composition
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Aluminium alloy is used widely in our society, but it is not good enough for many applications because it is soft. In order to harden the surface of the aluminium alloy, the surface is compounded by laser in this experiment. Here, two kinds of SiC power ,the diameters of which are nanometer-grade and micron-grade respeAluminium alloy is used widely in our society, but it is not good enough for many applications because it is soft. In order to harden the surface of the aluminium alloy, the surface is compounded by laser in this experiment. Here, two kinds of SiC power ,the diameters of which are nanometer-grade and micron-grade respectively , are compounded to the surface with Nd∶YAG pulsed laser separately. The experiment results show that.
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 765 (2004)
Laser Physics
Study on Resonator of 85 W All-Solid-State Green Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
In this paper, research on the resonator of a high-average-power high stabilization 85 W all-solid-state green laser was reported. The thermal effects of the KTP crystal operating at high-average-power condition were treated as a thin lens, and the effects of this thin lens on the stability and laser modes of the resonIn this paper, research on the resonator of a high-average-power high stabilization 85 W all-solid-state green laser was reported. The thermal effects of the KTP crystal operating at high-average-power condition were treated as a thin lens, and the effects of this thin lens on the stability and laser modes of the resonator were graphically discussed by ABCD matrix method. Theoretical analyses indicated that an optimum focal length of this thin lens would do a great deal of good to compensate thermal lens effect of Nd∶YAG rod, enlarge TEM00 mode volume and enhance the laser power density at KTP crystal. In the experiment, 20 W×80 high power laser diode arrays and double acousto-optic Q-switching were employed inside single Nd∶YAG rod, and a flat-concave intracavity-frequency-doubled resonance structure was used. A maximum green power of 85 W was generated at 20.4 kHz repetition rate and 230 ns pulse width when pumped power was about 1080 W with compensating phase mismatch by angle departuring and properly cooling big KTP crystal, leading to ±1.03% instability..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 641 (2004)
Study on SESAM Passively-Mode-Locked Nd∶YAG Laser
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A high-efficiency and stable ps mode-locked Nd∶YAG laser that used a semiconductor saturable absorber mirror (SESAM) is reported. This SESAM is made by ourselves. The mode-locked pulse duration is narrower than 10 ps, measured by autocorrelation. The optical-optical conversion efficiency of 19% with straight cavity is A high-efficiency and stable ps mode-locked Nd∶YAG laser that used a semiconductor saturable absorber mirror (SESAM) is reported. This SESAM is made by ourselves. The mode-locked pulse duration is narrower than 10 ps, measured by autocorrelation. The optical-optical conversion efficiency of 19% with straight cavity is attained..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 646 (2004)
Quasi-CW 17 kW 808 nm GaAs/AlGaAs Stack Laser Diode Arrays
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
High power 808nm laser diodes are widely used for pumping Nd∶YAG solid-state lasers. In this paper the design, fabrication and the test results of 17 kW GaAs/AlGaAs stack laser diode arrays are reported. In order to achieve higher power, one of approaches is to use a broad waveguide structure, which effectively reducesHigh power 808nm laser diodes are widely used for pumping Nd∶YAG solid-state lasers. In this paper the design, fabrication and the test results of 17 kW GaAs/AlGaAs stack laser diode arrays are reported. In order to achieve higher power, one of approaches is to use a broad waveguide structure, which effectively reduces the intensity on the facets and allows for higher output power. The structures were grown by metalorganic chemical vapor deposition. The output power of 100 W of 1 cm monolithic laser bars with a 80% filled factor has been abtained; Additionally, the stack structure was used. The laser diode array comprises 160 bars. The pitch of bars is 0.5 mm. The output power of 17 kW has been abtained. The emitting peak wavelength is 807.6 nm and FHWM is 4.9 nm..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 649 (2004)
Multi-Wavelength Raman Frequency Conversion in the Mixture of CH4 and H2
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A combinative technology of triple-frequency solid laser and SRS has been investigated to obtain multi-wavelength laser lines covering waveband from ultraviolet to visible. This technology could be applied in LIDAR such as measurement of air pollution. The SRS characteristics have been studied pumped by a triple-frequeA combinative technology of triple-frequency solid laser and SRS has been investigated to obtain multi-wavelength laser lines covering waveband from ultraviolet to visible. This technology could be applied in LIDAR such as measurement of air pollution. The SRS characteristics have been studied pumped by a triple-frequency Nd∶YAG laser in methane and a mixture gas of methane and hydrogen. Multiple wavelength lines were obtained simultaneously at 396 nm, 416 nm, 447 nm and 503 nm+515 nm with output power about 100 mW for each line. The characteristics of the most familiar Raman gases and a mixture gas of methane and hydrogen were also discussed. Comparing with the individual gas (methane or hydrogen), more abundant lines have been obtained in the mixture gas. Unlike strong decomposition in methane irradiated by UV laser, the decomposition was restrained by adding hydrogen in the mixture gas..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 677 (2004)
A Fast Algorithm for the Propagation of Partially Coherent Beams through a Multiple Hard-Edged Apertured ABCD Optical System
[in Chinese], and [in Chinese]
The propagation of partially coherent beams through an apertured paraxial ABCD optical system is an interesting but difficult problem encountered in practice. Although the integration based on the Collins formula can be evaluated numerically using such programs as “Mathematia”, it becomes very cumbersome and time consuThe propagation of partially coherent beams through an apertured paraxial ABCD optical system is an interesting but difficult problem encountered in practice. Although the integration based on the Collins formula can be evaluated numerically using such programs as “Mathematia”, it becomes very cumbersome and time consuming with increasing number of apertures. In this paper, by using the method of expanding the hard-edge aperture function into a finite sum of complex Gaussian functions, the recurrence propagation expression for the propagation of partially coherent beams through a multiple apertured ABCD optical system is derived, which provides a fast algorithm for simulating the propagation of partially coherent beams through hard-aperture optics. Numerical calculation examples are given, which show that the calculation results by using our analytical formula are consistent with those by straightforward integral of the Collins formula in the region not close to the aperture. THe main advantage of this method is the fast computation, so that the computing time can be greatly reduced. In addition, the extension to multi-apertured ABCD system is made, where the partial coherence of beams is taken into account, so that the expression is applicable to the more general case and is suitable to partially coherent multimode lasers..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 681 (2004)
Experimental Investigation on the Electron Density and Electron Temperature of Laser-Induced Al Plasmas
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The laser-induced plasma plays an important role in the trace element analysis. The properties of plasma are dependent on the kinds and pressure of buffer gas. With He, Ar, N2, Air as buffer gases respectively, the time-resolved emission spectra of laser induced Al plasmas at different pressure are measured. The electrThe laser-induced plasma plays an important role in the trace element analysis. The properties of plasma are dependent on the kinds and pressure of buffer gas. With He, Ar, N2, Air as buffer gases respectively, the time-resolved emission spectra of laser induced Al plasmas at different pressure are measured. The electron density and electron temperature of Nd∶YAG laser-induced Al plasma are calculated by the measured relative emission-line intensity and Stark broadening. The dependence of electron density on the time delay, kinds and pressure of the buffer gas are studied. The time evolution property of the electron temperature is also obtained. The experimental results show that the electron density and the electron temperature in laser induced Al plasmas are the order of 1017 cm-3 and 10000 K respectively. They are both decayed rapidly with the time delay from the laser pulse off and then changed slowly after 4 μs. Among several of buffer gases, the electron density is the largest in Ar gas..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 687 (2004)
Materials and Thin Films
Influence of Inert Gas Pressure on the Surface Roughness of Silicon Film Prepared by Pulsed Laser Deposition
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The surface roughness of Si film is an important parameter to describe its quality. In order to investigate the correlation between the surface roughness of silicon film prepared by pulsed laser deposition and gas pressure, by using Lambda Physik XeCl excimer laser, nanocrystalline silicon film is deposited in differenThe surface roughness of Si film is an important parameter to describe its quality. In order to investigate the correlation between the surface roughness of silicon film prepared by pulsed laser deposition and gas pressure, by using Lambda Physik XeCl excimer laser, nanocrystalline silicon film is deposited in different inert gas atmospheres such as He and Ar, by using Tencor Instruments Alpha-Step 200, the surface roughness of the sample is measured. The results show that with increasing gas pressure, the roughness of Si film first increases and reaches its maximum and then decrease, furthermore, the numerical value in Ar is less than that in He. The roughness maximum strongly depends on the inert gases used. For the heavier gas, Ar, the maximum is 11% higher than that in the case of very-low pressure, for the gas He, the corresponding values are 314%..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 698 (2004)
Influence of Deposition Temperature on the Properties of ZrO2 Films Prepared by Electron Beam Evaporation
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
ZrO2 films have been prepared by electron beam evaporation at different deposition temperature. The films have been characterized by X-ray diffraction (XRD) and atom force microscopy (AFM). At room temperatures, the structure of ZrO2 films is amorphous. With the increase of deposition temperature, the films begin to crZrO2 films have been prepared by electron beam evaporation at different deposition temperature. The films have been characterized by X-ray diffraction (XRD) and atom force microscopy (AFM). At room temperatures, the structure of ZrO2 films is amorphous. With the increase of deposition temperature, the films begin to crystallize. Both tetragonal and monoclinic phases have been found. All films show random orientation. The crystallite size increases as deposition temperature increases. The residual stress of ZrO2 films varies from tensile to compressive which was mainly caused by intrinsic stress. The influence of deposition temperature on the optical properties of ZrO2 films has been also discussed..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 701 (2004)
Measurement and Metrology
Detection of Nanometer Displacement in Optical-Tweezers and Its Related Measuring Errors
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Optical Tweezers can be used in measuring nanometer displacements of a particle with several micron diameters. Methods of measurement and data processing, error sources are analyzed. The dynamic image analysis methods including the gray centroid method and new developed methodsOptical Tweezers can be used in measuring nanometer displacements of a particle with several micron diameters. Methods of measurement and data processing, error sources are analyzed. The dynamic image analysis methods including the gray centroid method and new developed methods.
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 729 (2004)
Digital Speckle Correlation Method and Its Application on Impact Deformation Measurement
[in Chinese], [in Chinese], and [in Chinese]
A real-time and in situ optical measuring system is developed, which can be used to observe the deformation of structures under impacting loading. The system consists of the high-speed camera, digital acquisition, laser light source, synchronization controlling system and analysis software based on the digital correlatA real-time and in situ optical measuring system is developed, which can be used to observe the deformation of structures under impacting loading. The system consists of the high-speed camera, digital acquisition, laser light source, synchronization controlling system and analysis software based on the digital correlation theory. The optical system has been adapted to investigate the dynamic deformation fields of normal impact tension sample and plain plate with notches loaded by split Hopkinson tension device. Results obtained in experiments are discussed and compared with finite element simulations and classical Hopkinson bar method. It is proved partly that the measuring system, developed in this paper, is effective and valid..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 735 (2004)
New Method to Eliminate Extension of Zero Component in FTP
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Fourier transformation profilometry (FTP) is a non-contract and high speed optical 3-D measurement method. Here, a short-time Fourier transform is introduced into FTP to extract zero component included in deformed fringe pattern only employing one frame deformed fringe pattern. In this method, a window function is usedFourier transformation profilometry (FTP) is a non-contract and high speed optical 3-D measurement method. Here, a short-time Fourier transform is introduced into FTP to extract zero component included in deformed fringe pattern only employing one frame deformed fringe pattern. In this method, a window function is used to scan through whole deformed fringe image from left-top to right-bottom to form many partial fringe patterns. For each partial fringe, its normalized Fourier spectrum is calculated, the zero components are extracted and superimposed to restore the zero component. Then the normalized Fourier spectra of original deformed fringe pattern is calculated. Finally the zero component is subtracted from Fourier spectra of deformed fringe pattern. Eliminating zero component can extend the measuring range of Fourier transform profilometry to nearly three times of that of the traditional FTP as π phase-shifting technique does. Experiment verifies that it is an efficient method to extend measuring range and keep measuring speed. Compared to π phase-shifting technique, only one frame deformed fringe pattern is needed to eliminate the zero component. The setup is simple because of no phase shifting device needed..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 740 (2004)
Study on Self-Triggering Pulsed Time-of-Flight Laser Rangefinding
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Based on the self-triggering pulsed technique, a novel pulsed time-of-flight laser rangefinding method is proposed to improve the accuracy and measuring speed of laser distance measurement. The theoretical analysis is carried out, and three basic equations are presented to describe the methods. Furthermore, a measuremeBased on the self-triggering pulsed technique, a novel pulsed time-of-flight laser rangefinding method is proposed to improve the accuracy and measuring speed of laser distance measurement. The theoretical analysis is carried out, and three basic equations are presented to describe the methods. Furthermore, a measurement device is described and experimental evidence is presented to show the feasibility of measuring distance with 0.5 mm resolution over 20 m ranges..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 745 (2004)
An Improved Sensor of Extinction Particle Counter
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Particle counter of extinction type is used mainly to detect the particulate contamination of larger sizes, and widely applied in contamination control measurement and monitor, whereas it is unable to detect smaller sizes particulate, the reason is discussed in this paper. Based on Mie theory, extinction coefficient isParticle counter of extinction type is used mainly to detect the particulate contamination of larger sizes, and widely applied in contamination control measurement and monitor, whereas it is unable to detect smaller sizes particulate, the reason is discussed in this paper. Based on Mie theory, extinction coefficient is calculated, at the same time, the representative structure of this type sensor is analyzed. Numerous calculation and analysis showed that it is due to the ambiguity relationship of extinction coefficient versus particulate sizes less than 2 μm and unreasonable design. An improved design of the sensor was proposed, which employs a specially designed detecting lens unit to collect more scattered light and a monitoring device to control the light source, the lens of collecting scattering light is arranged at 45 degree, which can lead the good monodromy for light energy versus particulate sizes and less interference due to particle refractive index. Comparative experiments showed that the lower limit of the measuring size range could be extended by the new sensor design. The new sensor has a good detect ability for particle sizes less than 2 μm and lower repetition errors, and furthermore, it still has a high level for detecting larger sizes particle, it suits for more application of contamination degree monitoring..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 749 (2004)
Measurement of Low-Frequency Surface Acoustic Wave on Liquid Surface by Means of Laser Interference
[in Chinese], [in Chinese], and [in Chinese]
A laser interference technique for measuring liquid surface acoustic wave at a few tens Hertz was designed and the high visibility and modulated interference fringes, which are formed by the reflective light beam from the liquid surface, were obtained experimentally. The interference fringes are confined in a certain sA laser interference technique for measuring liquid surface acoustic wave at a few tens Hertz was designed and the high visibility and modulated interference fringes, which are formed by the reflective light beam from the liquid surface, were obtained experimentally. The interference fringes are confined in a certain space range and the double brightest spots locate at the both extreme positions of this range. An analytic intensity expression of the light from the liquid surface, the angle space of the interference fringes and the angle width of the interference fringe range with the surface acoustic wave were derived theoretically. The results show that the theory predication is well consistent with experimental data. Moreover, a practical technique can be developed, based on the discovery, to measure the properties of the surface wave at these frequencies and the dynamic surface tension..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 752 (2004)
Optical Communication
Spectral Characteristic of Alumina Codoping Erbium Doped Fiber Amplifier
[in Chinese], [in Chinese], and [in Chinese]
Alumina codoping can change the spectra of Er doped fiber amplifier (EDFA), which can be analyzed by Stark energy level splitting theory. Several types of EDFs with different alumina concentration were fabricated by modified chemical vapor deposition (MCVD) and solution doping method, and the fluorescence spectra of thAlumina codoping can change the spectra of Er doped fiber amplifier (EDFA), which can be analyzed by Stark energy level splitting theory. Several types of EDFs with different alumina concentration were fabricated by modified chemical vapor deposition (MCVD) and solution doping method, and the fluorescence spectra of the alumina codoping EDF amplifier was explored. The investigation showed that alumina codoping result in a shift of fluorescence toward shorter wavelength. The absorption coefficients of EDFs with different alumina doping concentration was measured by cutoff method, and the result demonstrate that increasing the alumina concentration in EDF will increase the concentration of Er, which can improve the absorption coefficients of EDF and shorten the length of EDF in EDFA. High alumina codoping EDFA have wider and flatter gain spectra, which can be used in long haul wavelength division multiplexing (WDM) system..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 705 (2004)
High Pump Conversion Efficiency and Broad L-Band ASE Source by Using Sagnac Feedback Loop
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Optical wideband source of L-band amplified spontaneous emission (ASE) from erbium doped fiber has extensive application in fiber sensors and device testing; here the pump power conversion is one of the key technique. In this work, based on the secondary pumping mechanism by C-band power for L-band signal, a Sagnac looOptical wideband source of L-band amplified spontaneous emission (ASE) from erbium doped fiber has extensive application in fiber sensors and device testing; here the pump power conversion is one of the key technique. In this work, based on the secondary pumping mechanism by C-band power for L-band signal, a Sagnac loop is used to feed-back the output of C-band ASE, the reflected C-ASE propagates along single direction in the fiber and is amplified in expending inversion population, so that the utility of pump power for L-band ASE is increased. Experimentally, the total output power was 14 dBm at 125 mW 980 nm pumping i.e. pump power conversion efficiency up to 20% was achieved. Without gain flatten filter, the 1 dB bandwidth was 31.1 nm (1568.9～1600 nm), so that high pump conversion efficiency and broad L-band ASE source was demonstrated..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 6, 709 (2004)
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