Papers by Keyword: Diode Laser

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Authors: Fabrizio Quadrini, Loredana Santo, Federica Trovalusci
Abstract: In the present study the use of diode laser for stainless steel aesthetic welding is considered. In fact the surface smoothness of the weld bead, attributed to the mode stability of the laser system, suggests its application for aesthetic weld joint. The aims of this work were to: define a process map, based on an aesthetic criterion; mechanically characterize the weld joints (by Vickers micro-hardness and tensile test); analyse the surface of the specimens in terms of roughness. Moreover, gas tungsten-arc (TIG) weld joints were carried out and analogously tested to make a comparison with the diode laser results. Good aesthetic butt joints were obtained with diode laser welding. The same results were found working with constant power speed ratio (i.e. constant fluence). Comparison between TIG and Laser Beam Welding (LBW), showed no significant difference in roughness, while ultimate tensile load was higher for TIG welding. The differences in joint strength depend on the different cross-sectional area and on the extension and microstructure of the base metal, heat-affected zone and melted zone. However, diode laser technology allows to obtain smaller bead size.
707
Authors: S. Guarino, Nadia Ucciardello, Vincenzo Tagliaferri
Abstract: In this paper a neural network approach is used to model the diode laser assisted forming process. In particular thin sheets of Aluminum alloy AA 6082 were bended in the elastic range and then treated with a diode laser with the aim to reduce the spring back phenomenon. Experimental tests were performed to study the influence of the process parameters such as laser power, laser speed and starting elastic deformation on the evolution of forming process. In particular the heating effects on the elastic properties of the material was studied. A statistical approach is used to define the experimental plan and discuss the experimental results. Interesting trend of the effects of the diode laser on the forming process were found. Subsequently in order to predict the residual inflexion, during the laser forming, a multilayer feedforward artificial neural network has been implemented. A sensitivity analysis on the artificial neural network model is used to show the significance of all the input data employed. As a result of sensitivity analysis, a check between experimental and calculated trends for each investigated variables was performed, which revealed an appreciable fit between data displayed.
325
Authors: Alexander Höink, Karl Meiners-Hagen, Otto Jusko, Ahmed Abou-Zeid
Abstract: The experimental results for the determination of the form of thin cylinders (Ø ~ 2.5 mm) as well as step heights of gauge blocks (~ 100 µm) and roundness profiles of test samples from metal or glass with different diameters between ~ 2.5 mm and 80 mm using two multi-wavelength diode laser interferometers are presented and discussed.
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Authors: Yuan Yuan Gu, Guo Xing Wu, Hui Lu, Jian Lin
Abstract: Direct diode lasers have some of the most attractive features of any laser. They are very efficient, compact, wavelength versatile, low cost, and highly reliable. However, the full utilization of direct diode lasers has yet to be realized. This is mainly due their poor output beam quality. Because of this, direct diode lasers are typically used to pump other lasers such as bulk solid-state (rod and thin disk) and fiber lasers. An improvement of the wall-plug efficiency and Power density necessary can be achieved by beam shaping and beam combination such as polarization coupling. In this paper, using the beam shaping technology realize good beam quality and high wall-plug efficiency. Base on bars rated to 60 W and 57% conversion efficiency, vertically stacked arrays (twenty bars) of such configuration are demonstrated with rated to about 1200W. The beam quality of high-power high brightness 880 nm laser diode source is improved with beam shaping. Beam parameter product of 79. 3 mm mrad ×81. 2 mm mrad, electro-optical conversion efficiency of more than 45.8% and continuous output power of 1 kW are demonstrated. This laser can be directly applied to cladding, surface hardening and other fields.
385
Authors: Juan Juan Li, Dong Ping Gi Yang, Gang Guo, Zheng Yan Li
Abstract: The digital Semiconductor Laser’s Driving Source is designed in this paper, in order to gain a constant current source, which the maximize output electric current is 40A; voltage is from 2V to 10V. Based on the requirement of very task, the part of driving and the part of constant temperature control, which is auxiliary designed, are made of the controller of semiconductor laser diode. As the result, the whole of designs ensure the diode laser to work stably.
1381
Authors: Aleksander Lisiecki
Abstract: The heat conditions of laser gas nitriding (LGN) of titanium alloy Ti6Al4V by high power diode laser (HPDL) were investigated experimentally by non-contact pyrometric measurements and infrared camera analysis. Additionally direct observations of the weld pool shape were conducted by means of high speed digital camera. In the numerical study of the laser surface processing of titanium plate 3D model of heat flow was examined. Results of temperature values, distribution and temperature isotherms obtained from the 3D model were next applied in the two-dimensional stationary model of liquid metal flow in the weld pool. Experimental and numerical study showed that the temperatures of the weld pool during laser gas nitriding of the titanium alloy are significantly higher compared to these determined during laser melting in argon atmosphere at the same heat input. Additionally severe turbulences of liquid metal in the weld poll (Marangoni convection) were found during both experimental and numerical analysis.
320
Authors: R. Ikutomo, Masato Tsujikawa, Makoto Hino, Hisamichi Kimura, Kunio Yubuta, Akihisa Inoue
Abstract: Bulk metallic glass (BMG) exhibits remarkable properties such as high strength, good stiffness and good corrosion resistance. However, the wear resistance of amorphous metals is not excellent as expected their high strength. It is thought that large local shear bands easily change into cracks for debris formation. The effective obstruction of shear band formation might be applied to improve the wear resistance of BMG. In this study, we tried to suppress shear band deformation by fine crystalline phase dispersion formed by semi-conductor laser irradiation. The microstructures of irradiated Zr-based BMG specimens were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The fine dispersions of crystalline phases are observed in the amorphous matrix. The optimum condition for laser irradiation was discussed.
747
Authors: Xiao Dong Liu, Hai Dong Lei, Jian Jun Zhang
Abstract: The Semiconductor laser frequency stabilization is the important study topic because of its increasing popular. We introduce a simply experimental setup method of the frequency stabilization of a 780 nm diode laser by only a tiny current in the laser audio modulation, photodiode receiver, and locking the transmission peaks. Use this method, the laser can be locked to the resonance peak of the Fabry-Perot cavity. The linewidth of laser is below 400 kHz, and it runs continually above 3 hours.
1235
Authors: Yuan Yuan Gu, Guo Xing Wu, Hui Lu, Yan Cui
Abstract: High-power diode lasers based on GaAs semiconductor bars are well established as reliable and highly efficient laser sources. The device structure and stack technology of edge-emitting diode laser were presented briefly as well as the development of electro-optical conversion efficiency ,lifetime , power .The technology of ten-thousand –watt level high power diode laser was introduced as a new generation of laser processing equipment. In order to output high power, we utilized polarization coupling technology to couple two 808nm and 880nm laser diode stack together, and designed the optical system to expand and focus the beam, through the experiment; we realize the overall efficiency more than 90%, power output 1000W.
1852
Authors: Yuan Yuan Gu, Guo Xing Wu, Hui Lu, Yan Cui
Abstract: As the increasing applications of laser diodes in laser cladding and laser hardening, the single laser diode 0ptical power can not meet the actual requirements. An improvement of the power and Power densty necessary and it can be achieved by beam shaping and beam combination such as polarization coupling the polarization coupling technology is used to couple two laser beams with thin film plate polarizer In this paper two 880 nm vertical stacked arrays with an output power of l600 W was achieved After fast axils and slow axis collimated, the polarization direction of one stacked arrays is rotated 90 degree through a half wave plate, thus, the polarization directions of two laser stack are vertica1. The beams of two lasers are incident on the p1ate po1arizer, one transmits through it, and the other is reflected on it. Finally, two beams combine to one. Polarization coupling of two bars increases the power by a factor of 1.6, and the output power is 2500 W, electro optical conversion efficiency is more than 48%. The spot size is about2 mm x 2 mm. This laser can be directly applied to cladding, surface hardening and other fields.
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