Browsing by Subject "Laser applications"
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Item Open Access Computer vision based unistroke keyboard system and mouse for the handicapped(IEEE, 2003-07) Erdem, M .Erkut; Erdem, İ. Aykut; Atalay, Volkan; Çetin, A. EnisIn this paper, a unistroke keyboard based on computer vision is described for the handicapped. The keyboard can be made of paper or fabric containing an image of a keyboard, which has an upside down U-shape. It can even be displayed on a computer screen. Each character is represented by a non-overlapping rectangular region on the keyboard image and the user enters a character by illuminating a character region with a laser pointer. The keyboard image is monitored by a camera and illuminated key locations are recognized. During the text entry process the user neither have to turn the laser light off nor raise the laser light from the keyboard. A disabled person who has difficulty using his/her hands may attach the laser pointer to an eyeglass and easily enter text by moving his/her head to point the laser beam on a character location. In addition, a mouse-like device can be developed based on the same principle. The user can move the cursor by moving the laser light on the computer screen which is monitored by a camera. © 2003 IEEE.Item Open Access Modeling and cross coupling controller development for a 6DOF laser micro-machining system(IEEE, 2017) Kerimoğlu, Serhat; Çakmakçı, MelihIn recent years, studies on manufacturing systems have proved the importance of cooperation of positioning systems with laser cutting technology. The performance of the manufacturing system can be improved by utilizing both laser and positioning systems together. In this study, modeling and cross coupling controller development of a micromachining system which can perform on non-linear contoured surfaces is presented. Laser micromachining system is designed and assembled including a nanosecond Q-switched pulsed fiber laser, a 6-DOF hexapod manipulator, a granite table in order to absorb vibrations and an external cabin system to isolate the whole system for safety and health issues. The positioning system used here has fast response and precise positioning capabilities with a wide range of workspace. However, its performance of machining non-linear surfaces can be further improved by using a cross coupled control algorithm. On top of the loop based controllers an add-on controller is developed to improve the contouring performance by including the effects of the other feedback loops on the overall controller. Actual laser cutting results also show improvements due to the improvements in the positioning system performance.Item Open Access Performance evaluation of ultrasonic arc map processing techniques by active snake contours(2008) Altun, K.; Barshan, B.Active snake contours are considered for representing the maps of an environment obtained by different ultrasonic arc map (UAM) processing techniques efficiently. The mapping results are compared with the actual map of the room obtained with a very accurate laser system. This technique is a convenient way to represent and compare the map points obtained with different techniques among themselves, as well as with an absolute reference. It is also applicable to map points obtained with other mapping techniques. © 2008 Springer-Verlag Berlin Heidelberg.Item Open Access q-Gaussian trial function in high density Bose-Einstein condensates(Elsevier Science B.V., 2003) Erdemir, E.; Tanatar, BilalWe study the ground-state static properties of Bose-Einstein condensates in the high density regime using a trial wave function of the form of a q-Gaussian. The flexibility afforded by a q-Gaussian trial function yields very accurate ground-state energies for large number of particles. The resulting condensate wave function profiles are also in good agreement in the high density regime. Comparing our results with those of numerical calculations we provide information on the possible limitations of the q-Gaussian trial functions.Item Open Access Raman studies of doped polycrystalline silicon from laser-annealed, doped a-Si:H(Pergamon Press, 1994) Compaan, A.; Savage, M. E.; Aydınlı, Atilla; Azfar, T.We have used Raman scattering to follow the progress of multiple-pulse (sub-melt-threshold) laser annealing in doped hydrogenated amorphous silicon films (a-Si:H) on glass. In phosphorous-doped a-Si:H the Raman signal shows that recrystallization begins with the first laser pulse but the multiple pulses are needed to generate the highest hole concentrations of ∼6×1020 cm-3. In boron-doped a-Si:H the electron concentration reaches ∼1×1021 cm-3 after laser anneal which produces a dip rather than a peak near the phonon line as a consequence of a negative Fano-interference parameter, q. The results show that Raman scattering can be used to obtain carrier concentrations in poly-silicon provided that wavelength-dependent Fano interference effects are properly included. © 1994.Item Open Access Surfactant-mediated growth of semiconductor materials(Institute of Physics Publishing, 2002) Fong, C. Y.; Watson, M. D.; Yang, L. H.; Çıracı, SalimDuring epitaxial growth of semiconducting materials using either molecular beam epitaxy or organometallic vapour deposition, the addition of a surfactant can enhance two-dimensional layer-by-layer growth. This modified growth process is now called the surfactant-mediated growth (SMG) method. It has had an important impact on the development of technologically important materials in device applications, such as heterostructures used for laser applications. Recent developments that use surfactants to improve doping profiles in semiconducting systems and antisurfactants (ASMG) to grow quantum dots further ensure that SMG/ASMG will play a major role in the future development of optoelectronic materials and nanoparticles. In this paper, we review important earlier experimental work involving the SMG method as well as some recent developments. Theoretical work involving first-principles methods and kinetic Monte Carlo simulations are discussed but confined only to the surfactant effect.