Journals >Chinese Journal of Lasers
Contents
1996
Volume: 23 Issue 12
16 Article(s)
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Research Article
Design and Measurement of Focal lengths of Lenses of Large f -number Used in Spatial Filters in a High Power Solid-state Laser System
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Some Problems, which are concerned with the focal lengths of lenses used in spatial filters in a high power solid-state laser system, are investigated. And, a method suitable for measuring the focal lengths of lenses, the f-numbers of which are larger than these of the usual ones, is also introduced.Some Problems, which are concerned with the focal lengths of lenses used in spatial filters in a high power solid-state laser system, are investigated. And, a method suitable for measuring the focal lengths of lenses, the f-numbers of which are larger than these of the usual ones, is also introduced..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 23, Issue 12, 1077 (1996)
A Method to Increase the Depth Resolution in Laser Triangulation
[in Chinese], [in Chinese], and [in Chinese]
Laser triangulation is one of the most important 3-D sensing profilometries.Because of the influence of image speckle, the determination of the centroid of light spot in CCD surface is limited. This causes the depth resolution decreased. In this article, we present a method that is based on the lateral shift of the objLaser triangulation is one of the most important 3-D sensing profilometries.Because of the influence of image speckle, the determination of the centroid of light spot in CCD surface is limited. This causes the depth resolution decreased. In this article, we present a method that is based on the lateral shift of the object. When the shift distance reaches to the diameter of the point spread function, the correlation of the centroid line of laser sheet is decreased evidently. We increase the depth resolution is increased one time while the lateral resolution is deceased only 18%..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 23, Issue 12, 1081 (1996)
Measurements of Transient Thermal Characteristics in Power Devices with a Noninvasive Laser Probe
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A low-coherence laser interferometry has been proposed to measure temperature of power devices. The transient thermal characteristic in power transistors has been measured in real time with a InGaAsP LD used as a microprobe. The experimental results show that this method is accurate and noninvasive. It also has the advA low-coherence laser interferometry has been proposed to measure temperature of power devices. The transient thermal characteristic in power transistors has been measured in real time with a InGaAsP LD used as a microprobe. The experimental results show that this method is accurate and noninvasive. It also has the advantages of high spatial resolution, quick response speed, and a wide measuring range. It is applicable to power electronics and optoelectronics devices fabricated with Si, GaAs, and InP materials..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 23, Issue 12, 1087 (1996)
Comparison of the Two Optical Scanning Paths in a Laser Pulse Forming System by a Pair of Electro-optic Deflectors
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
In this paper, we compare the two optical scanning paths which have been used in the forming of the laser pulse, and discuss their advantages and disadvantages. A method is presented to evaluate the restoring accuracy of the scan-line of the laser pulse which will find an important application in the exprimental work oIn this paper, we compare the two optical scanning paths which have been used in the forming of the laser pulse, and discuss their advantages and disadvantages. A method is presented to evaluate the restoring accuracy of the scan-line of the laser pulse which will find an important application in the exprimental work of the "SHENGUANG Ⅱ" upgrading system..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 23, Issue 12, 1091 (1996)
Picosecond Electro-optic Sampling by an External Probe with a Laser Diode
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A non-contact electro-optic sampling using a LiTaO3 probe is described. A gainswitched LD has been used to measure electric pulses generated by a comb generator. The result is compared with that obtained by an electrical sampling oscilloscope. The time resolution is 25 ps and the minimum detectable voltage of 20 mV is A non-contact electro-optic sampling using a LiTaO3 probe is described. A gainswitched LD has been used to measure electric pulses generated by a comb generator. The result is compared with that obtained by an electrical sampling oscilloscope. The time resolution is 25 ps and the minimum detectable voltage of 20 mV is obtained..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 23, Issue 12, 1097 (1996)
Collinear-beam Acoustic Optical Tunable Filter
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
APTF possesses a unique function of optical wavelength tuning for the use of the optical communication AOTF technique. BC-AOTF has advantages of both collinear and noncollinear AOTFs at the same time. Optational principle and design method have been presented. A 98% diffraction efficiency at 20 mW, 33 dB side-lobes supAPTF possesses a unique function of optical wavelength tuning for the use of the optical communication AOTF technique. BC-AOTF has advantages of both collinear and noncollinear AOTFs at the same time. Optational principle and design method have been presented. A 98% diffraction efficiency at 20 mW, 33 dB side-lobes suppression and a 0.8 nm. A spectral line width have been achieved..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 23, Issue 12, 1100 (1996)
Holography and Information Processing
A New Technique for Reference Fringes in Dynamic Holography
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
We present a new technique for reference fringeS in the double-pulsed hologaphic interferometry. The technique is based on a vibrating mirror which was driven by an electronic tuning fork. The spacing and orientation of the fringes are adjustable and duplicatable.We present a new technique for reference fringeS in the double-pulsed hologaphic interferometry. The technique is based on a vibrating mirror which was driven by an electronic tuning fork. The spacing and orientation of the fringes are adjustable and duplicatable..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 23, Issue 12, 1103 (1996)
Laser Manufacturing
Study on Laser Welding of Cast Nickel-base Superalloy
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
An investigation on CO2laser welding of cast nickel-base superalloy has been carried out. The effects of the main parameters, including the laser power, the welding speed, the position of the focal point and the direction of plasma-supressing gas on the depth and width of the bead were studied. The mechanism of hot-craAn investigation on CO2laser welding of cast nickel-base superalloy has been carried out. The effects of the main parameters, including the laser power, the welding speed, the position of the focal point and the direction of plasma-supressing gas on the depth and width of the bead were studied. The mechanism of hot-cracking in the weld metal and the heat-affect-zone (HAZ) was investigated while the methods to reduce the cracking susceptibiliy were discussed. The results show that a defects-free joint with high tensile strength can be obtained when using proper laser welding parameters..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 23, Issue 12, 1107 (1996)
Effects of Laser Shock Processing on the Fatigue Life of Fastener Holes
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
This paper reports an investigation of laser shock processing (LSP) used as a method to improve the service time of fastener holes. A series of experiments to optimize the LSP parameters were carried out carefully. On the basis of the data obtained, a group of fatigue tests have been done. The results show that the fatThis paper reports an investigation of laser shock processing (LSP) used as a method to improve the service time of fastener holes. A series of experiments to optimize the LSP parameters were carried out carefully. On the basis of the data obtained, a group of fatigue tests have been done. The results show that the fatigue lifetime of fastener holes treated by LSP can be increased significantly. It is expected that LSP will be used as a good treatment for improving the fatigue life of aviation structures..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 23, Issue 12, 1112 (1996)
Study of Laser Parameters Optimum of Laser Shocking Against Fatigue and Fracture of Metal
[in Chinese], and [in Chinese]
The influence of laser shock-processing (LSP) parameeters on the fatigue life of aluminum alloy 2024-T62 is described. If the duration of a laser is 50 ns, there is a heat damage on the LSP area of the specimen surface, and there is no improvemet on the fatigue life of metal. If the duration is 13 ns, there is no apparThe influence of laser shock-processing (LSP) parameeters on the fatigue life of aluminum alloy 2024-T62 is described. If the duration of a laser is 50 ns, there is a heat damage on the LSP area of the specimen surface, and there is no improvemet on the fatigue life of metal. If the duration is 13 ns, there is no apparent plastic deformation, and there is a little improvement on the fatigue life. If the duration is 30 ns, on the surface of the specimen there is a densified hollow LSP area that is very shiny, and the fatigue life is increased greatly. With 95% confidence, the fatigue life of LSP specimen is 4.2～8.1 times larger than the unprocessed specimen..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 23, Issue 12, 1117 (1996)
Wear Resistance of Laser Strengthened High Speed Steel and Cutting Property of the Tools
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
In this paper the structure and wear resistance of laser strengthened W18Cr4V high speed steel are studied, and the cutting property and failure form of the tools are discussed. The test results indicate that the properties of the laser strengthened layer have been improved greatly compered with those of the steel and In this paper the structure and wear resistance of laser strengthened W18Cr4V high speed steel are studied, and the cutting property and failure form of the tools are discussed. The test results indicate that the properties of the laser strengthened layer have been improved greatly compered with those of the steel and tools heat-treated commonly.The hardness can reach 1000Hv0.1. The toughness of laser strengthened layer is also improved remarkably, and the wear resistance is increased by 2～8 times. The service life of laser strengthened cutting tools of high speed steel can be prolonged by 2～5.7 times than the non-laser-treated ones..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 23, Issue 12, 1121 (1996)
A Three-dimensional Numerical Model for Laser Transformation Hardening of Metals
[in Chinese], and [in Chinese]
A three-dimensional numerical model for laser surface transformation hardening of metals using the finite differential technique is given in this peper. The model takes into account the finite dimensions of the workpiece, the temperature dependence of thermalPhysical properties of the material, the laser processing parA three-dimensional numerical model for laser surface transformation hardening of metals using the finite differential technique is given in this peper. The model takes into account the finite dimensions of the workpiece, the temperature dependence of thermalPhysical properties of the material, the laser processing parameters, and the surface heat losses due to convection and radiation. According to the model a three- dimensional temperature distribution on the surface and inside the workpiece can be obtained. The model can also be used to predict the phase transformation depth resulting from the laser surface treatment. Good agreement is demonstrated with experimental results for laser hardening of a zirconium alloy..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 23, Issue 12, 1127 (1996)
Laser Physics
CW Output and High Repetitive Passive Q-switching of a Nd:YVO4Laser Coupled Directly by a Laser Diode
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A laser diode directly coupled CW Nd:YVO4 laser is reported. The pump threshold of about 22 mW and the maximum output of about 172 mW in TEM00-mode are obtained with a slope efficiency of 35. 8 percent. By using a Cr4+:YAG chip in the laser cavity as a saturable absorber, a laser diode continuously pumped Nd:YVO4 laserA laser diode directly coupled CW Nd:YVO4 laser is reported. The pump threshold of about 22 mW and the maximum output of about 172 mW in TEM00-mode are obtained with a slope efficiency of 35. 8 percent. By using a Cr4+:YAG chip in the laser cavity as a saturable absorber, a laser diode continuously pumped Nd:YVO4 laser is passively Q-switched for the first time. haser pulses of 114 ns duration are produced with a repetition rate of as much as 380 kHz..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 23, Issue 12, 1057 (1996)
Changes in High-power laser Beams Passing through a Pulsed-laser Amplifier
[in Chinese], and [in Chinese]
By using the Pulse-sequence model, changes in Pulse profiles and fluence of laser heams of arbitrary spatial and temporal profiles after passing through a pulsed-laser amplifier with an arbitrary gain distribution have been studied in detail. Moreover, numerical calculations have been performed and compared for two casBy using the Pulse-sequence model, changes in Pulse profiles and fluence of laser heams of arbitrary spatial and temporal profiles after passing through a pulsed-laser amplifier with an arbitrary gain distribution have been studied in detail. Moreover, numerical calculations have been performed and compared for two cases: (1) the losses can be substituted approximately by a total loss factor T, and (2) the medium is divided into a series of thin slabs with certain gain distributions and loss factors Ti(T=ⅡiTi). As a result, the condition of the total-loss-factor approximation has been given..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 23, Issue 12, 1061 (1996)
Self-starting, Operation of a Self-mode-locked Ti:sapphire Laser with Low Pump Power and Its CW Operation
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A self-starting, stable ultrashort-pulsed Ti:sapphire laser with low pump power was demonstrated without additional materials or slit. The laser Produced stable pulses of 24.6 fs. A bandwidth of 53 nm was observed which would correspond to less than 13 fs according to an ideal value of 0.315 for time-bandwidth Product.A self-starting, stable ultrashort-pulsed Ti:sapphire laser with low pump power was demonstrated without additional materials or slit. The laser Produced stable pulses of 24.6 fs. A bandwidth of 53 nm was observed which would correspond to less than 13 fs according to an ideal value of 0.315 for time-bandwidth Product. Pumping threshold of CW operation was 0.2 W, and the output power was up to 1.1 W with an efficiency of 35%..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 23, Issue 12, 1067 (1996)
Active-passive Mode-locking in a Fiber Ring Soliton Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
In this paper a fiber ring soliton laser is analysed by solving the path-averaged NLSE. The conditions under which the laser would run stablely are given. We have also used the split-step algorithm for numerically integrating NLSE (1～4 ) and acquired a 985 fs transform-limited pulse train at a repetition rate of 10 GHzIn this paper a fiber ring soliton laser is analysed by solving the path-averaged NLSE. The conditions under which the laser would run stablely are given. We have also used the split-step algorithm for numerically integrating NLSE (1～4 ) and acquired a 985 fs transform-limited pulse train at a repetition rate of 10 GHz when λ= 1.55 μm..
Chinese Journal of Lasers
- Publication Date: Jan. 01, 1900
- Vol. 23, Issue 12, 1072 (1996)
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