Current Issue : January - March Volume : 2013 Issue Number : 1 Articles : 5 Articles
Recently, laser cutting is used in many industries. Generally, in laser cutting of metallic materials, suitable assist gas and its nozzle \r\nare needed to remove the molten metal. However, because of the gas nozzle should be set closer to the surface of a workpiece, \r\nexistence of the nozzle seems to prevent laser cutting from being used flexible. Therefore, the new cutting process, Assist Gas Free \r\nlaser cutting or AGF laser cutting, has been developed. In this process, the pressure at the bottom side of a workpiece is reduced \r\nby a vacuum pump, and the molten metal can be removed by the air flow caused by the pressure difference between both sides \r\nof the specimen. In this study, cutting properties of austenitic stainless steel by using AGF laser cutting with 2 kW CO2 laser were \r\ninvestigated. Laser power and cutting speed were varied in order to study the effect of these parameters on cutting properties. As \r\na result, austenitic stainless steel could be cut with dross-free by AGF laser cutting. When laser power was 2.0 kW, cutting speed \r\ncould be increased up to 100 mm/s, and kerf width at specimen surface was 0.28 mm....
GaInNAs was proposed and created in 1995. It can be grown pseudomorphically on a GaAs substrate and is a light-emitting\r\nmaterial with a bandgap energy that corresponds to near infrared. By combining GaInNAs with GaAs, an ideal band lineup\r\nfor laser-diode application is achieved. This paper presents the reproducible growth of high-quality GaInNAs by molecular\r\nbeam epitaxy. Examining the effect of nitrogen introduction and its correlation with impurity incorporation, we find that Al\r\nis unintentionally incorporated into the epitaxial layer even though the Al cell shutter is closed, followed by the concomitant\r\nincorporation of O and C. A gas-phase-scattering model can explain this phenomenon, suggesting that a large amount of N2 gas\r\ncauses the scattering of residual Al atoms with occasional collisions resulting in the atoms being directed toward the substrate.\r\nHence, the reduction of the sublimated Al beam during the growth period can suppress the incorporation of unintentional\r\nimpurities, resulting in a highly pure epitaxial layer....
We report the discovery of about 140 new energy levels of the neutral praseodymium atom, found by means of laser-induced\r\nfluorescence spectroscopy. Their energy has been determined with an uncertainty of 0.010 cm-1 using a wave number calibrated\r\nFourier-transform spectrum....
Molecular and particulate contamination of space optical surfaces can be extremely detrimental to optical system performance. In\r\norder to determine whether optical system is unusable, we must do a lot of tests. For reducing experimental effort, computational\r\ncriterion for unusable space optical system is put forward, which is based on experimentation and calculation by 2D-FDTD (finitedifference\r\ntime domain). And then factors making optical system unusable are studied when distribution of light intensity is\r\nconsistent with the criterion. Results show that small particulate is more detrimental to optical system than big one for particle\r\nwith high permittivity is. The distribution of particles making optical system unusable is also obtained....
The encoding of information in time intervals of an echelon of laser pulses of an object pulse in the optical echo processor\r\nis considered. The measures of information are introduced to describe the transformation of classical information in quantum\r\ninformation. It is shown that in the description of information transformation into quantum information, the most appropriate\r\nmeasure is a measure of quantum information based on the algorithmic information theory....
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