http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2013 , Hindawi Publishing Corporation . All rights reserved. Tue, 07 May 2013 08:52:10 +0000 http://www.hindawi.com/journals/aot/2013/532670/ A methodology for processing spectroscopic information using a chemometrics-based analysis was designed and implemented in the detection of highly energetic materials (HEMs) in the gas phase at trace levels. The presence of the nitroaromatic HEM 2,4-dinitrotoluene (2,4-DNT) and the cyclic organic peroxide triacetone triperoxide (TATP) in air was detected by chemometrics-enhanced vibrational spectroscopy. Several infrared experimental setups were tested using traditional heated sources (globar), modulated and nonmodulated FT-IR, and quantum cascade laser- (QCL-) based dispersive IR spectroscopy. The data obtained from the gas phase absorption experiments in the midinfrared (MIR) region were used for building the chemometrics models. Partial least-squares discriminant analysis (PLS-DA) was used to generate pattern recognition schemes for trace amounts of explosives in air. The QCL-based methodology exhibited a better capacity of discrimination for the detected presence of HEM in air compared to other methodologies. Leonardo C. Pacheco-Londoño, John R. Castro-Suarez, and Samuel P. Hernández-Rivera Copyright © 2013 Leonardo C. Pacheco-Londoño et al. All rights reserved. Wed, 13 Mar 2013 11:54:00 +0000 http://www.hindawi.com/journals/aot/2013/459074/ Ovidio Salvetti, Laura Abbozzo Ronchi, Carlo Corsi, Antoni Rogalski, and Marija Strojnik Copyright © 2013 Ovidio Salvetti et al. All rights reserved. Wed, 13 Mar 2013 09:15:22 +0000 http://www.hindawi.com/journals/aot/2013/905870/ We propose, evaluate, and demonstrate the performance of an IR/optical double-image experimental setup where we capture two simultaneous images of a single object, in two different spectral bands, using a single detector array. With this arrangement, we may observe rapidly changing phenomena, at a rate of more than 1000 frames per second, without the loss of the spatial information about the test subject. We describe the optical system to perform simultaneous imaging in IR for slightly inclined optical axes. We verify the actual performance by applying the experimental method to flame analysis in the mid-IR to determine the combustion efficiency. Marija Strojnik and Gonzalo Paez Copyright © 2013 Marija Strojnik and Gonzalo Paez. All rights reserved. Sun, 17 Feb 2013 15:12:02 +0000 http://www.hindawi.com/journals/aot/2013/314906/ Active thermography gives the possibility to characterize thermophysical properties and defects in complex structures presenting heterogeneities. The produced thermal fields can be rapidly 3D. On the other hand, due to the size of modern thermographic images, pixel-wise data processing based on 1D models is the only reasonable approach for a rapid image processing. The only way to conciliate these two constraints when dealing with time-resolved experiments lies in the earlier possible detection/characterization. This approach is illustrated by several different applications and compared to more classical methods, demonstrating that simplicity of models and calculations is compatible with efficient and accurate identifications. Daniel L. Balageas Copyright © 2013 Daniel L. Balageas. All rights reserved. Tue, 12 Feb 2013 15:28:12 +0000 http://www.hindawi.com/journals/aot/2013/794728/ We present a novel nonlocal mean (NLM) algorithm using an anisotropic structure tensor to achieve higher accuracy of imaging denoising and better preservation of fine image details. Instead of using the intensity to identify the pixel, the proposed algorithm uses the structure tensor to characterize the boundary information around the pixel more comprehensively. Meanwhile, similarity of the structure tensor is computed in a Riemannian space for more rigorous comparison, and the similarity weight of the pixel (or patch) is determined by the intensity and structure tensor simultaneously. The proposed algorithm is compared with the original NLM algorithm and a modified NLM algorithm that is based on the principle component analysis. Quantitative and qualitative comparisons of the three NLM algorithms are presented as well. Xi Wu, Mingyuan Xie, Wei Wu, and Jiliu Zhou Copyright © 2013 Xi Wu et al. All rights reserved. Tue, 12 Feb 2013 12:01:32 +0000 http://www.hindawi.com/journals/aot/2013/487121/ An experimental investigation of multiphase flow involving a liquid (water) and a gas (air) is performed. The results for three different scenarios are presented: fixed bubble, ascending bubble, and dispersed-bubble turbulent pipe flow. This study involves a comparison of statistical data collected using two sensing systems, a wavefront sensor and a high-speed video camera. A signal analysis technique based on signal attenuation is developed for data collected using the wavefront sensor. The three experiments performed provide experimental evidence that the Shack-Hartmann wavefront sensor, operating on signal attenuation, is a viable method for the study of multiphase bubble flows. H. Coronado Diaz and Ronald J. Hugo Copyright © 2013 H. Coronado Diaz and Ronald J. Hugo. All rights reserved. Tue, 15 Jan 2013 11:10:30 +0000 http://www.hindawi.com/journals/aot/2013/295950/ The theoretical description of a simplified end-to-end software tool for simulation of data produced by optical instruments, starting from either synthetic or airborne hyperspectral data, is described and some simulation examples of hyperspectral and panchromatic images for existing and future design instruments are also reported. High spatial/spectral resolution images with low intrinsic noise and the sensor/mission specifications are used as inputs for the simulations. The examples reported in this paper show the capabilities of the tool for simulating target detection scenarios, data quality assessment with respect to classification performance and class discrimination, impact of optical design on image quality, and 3D modelling of optical performances. The simulator is conceived as a tool (during phase 0/A) for the specification and early development of new Earth observation optical instruments, whose compliance to user’s requirements is achieved through a process of cost/performance trade-off. The Selex Galileo simulator, as compared with other existing image simulators for phase C/D projects of space-borne instruments, implements all modules necessary for a complete panchromatic and hyper spectral image simulation, and it allows excellent flexibility and expandability for new integrated functions because of the adopted IDL-ENVI software environment. Peter Coppo, Leandro Chiarantini, and Luciano Alparone Copyright © 2013 Peter Coppo et al. All rights reserved. Sun, 30 Dec 2012 11:38:59 +0000 http://www.hindawi.com/journals/aot/2012/206358/ Borja Vidal, Nathan J. Gomes, Tadao Nagatsuma, and Thomas E. Darcie Copyright © 2012 Borja Vidal et al. All rights reserved. Sun, 30 Dec 2012 11:15:22 +0000 http://www.hindawi.com/journals/aot/2012/738943/ The researchers focus on the IRT procedure of heat diffusion in ceramic finishing materials of contemporary architecture. The aim of the research is the development of a method for the thermal characterization of clinkers, a very common ceramic finishing material of buildings. The first experimental phase was performed in laboratory on clinkers of different shapes, thickness, colors, and glazing surface. The researchers determined two characteristic parameters related to thickness and thermal conductivity, by the interpolation of the heating curve in function of time with an analytical curve (resulted from a particular solution of Fourier’s equation). This curve allows to obtain a parameter characteristic of the material of the specimens under investigation. At present time, the researchers have been studying the correlation between this parameter and the damage level in the specimens; they will be testing the model on real-scale study cases in the second experimental phase. N. Ludwig, E. Rosina, S. Caglio, M. Gargano, and V. Redaelli Copyright © 2012 N. Ludwig et al. All rights reserved. Thu, 13 Dec 2012 07:59:44 +0000 http://www.hindawi.com/journals/aot/2012/484650/ The emissivity corrected thermal imaging combined with a real-time direct imposed-signal system on the freezing of biological cells is presented, which makes it possible to visualize the exothermic latent heat at a minus temperature. The applicability of the uncooled micro bolometer (thermal detector) to the micro-scale thermal analysis on the phase transitions of organic and polymeric materials is discussed in comparison with the photon detector, equipped with the optics originally designed. J. Morikawa, E. Hayakawa, and T. Hashimoto Copyright © 2012 J. Morikawa et al. All rights reserved. Mon, 10 Dec 2012 14:17:31 +0000 http://www.hindawi.com/journals/aot/2012/373926/ In the textiles production industry it is more and more common to advertise new textiles, especially for sportswear, by claiming their ability to emit IR radiation in the long wave band at a higher degree with respect to normal clothes, that is highly beneficial to improve sporting performances. Three textiles are compared, one normal and two “special,” with Ag+ ions and carbon powder added, with different colors. The emissivity of the textiles has been measured to determine if it is increased in the “special” textiles with respect to the normal one. No substantial increase has been noticed. Nonetheless, the test implied some nonstandard procedures due to the semitransparent nature of the textiles, in comparison with the normal procedure that is commonly used on opaque surfaces. P. Bison, A. Bortolin, G. Cadelano, G. Ferrarini, and E. Grinzato Copyright © 2012 P. Bison et al. All rights reserved. Sun, 09 Dec 2012 08:35:00 +0000 http://www.hindawi.com/journals/aot/2012/593893/ The improvement of surface properties such as laser hardening becomes very important in present manufacturing. Resulting laser hardening depth and surface hardness can be affected by changes in optical properties of material surface, that is, by absorptivity that gives the ratio between absorbed energy and incident laser energy. The surface changes on tested sample of steel block were made by engraving laser with different scanning velocity and repetition frequency. During the laser hardening the process was observed by infrared (IR) camera system that measures infrared radiation from the heated sample and depicts it in a form of temperature field. The images from the IR camera of the sample are shown, and maximal temperatures of all engraved areas are evaluated and compared. The surface hardness was measured, and the hardening depth was estimated from the measured hardness profile in the sample cross-section. The correlation between reached temperature, surface hardness, and hardening depth is shown. The highest and the lowest temperatures correspond to the lowest/highest hardness and the highest/lowest hardening depth. J. Tesar, P. Vacikova, O. Soukup, and S. Houdkova Copyright © 2012 J. Tesar et al. All rights reserved. Tue, 04 Dec 2012 15:47:24 +0000 http://www.hindawi.com/journals/aot/2012/838752/ Infrared science and technology has been, since the first applications, mainly dedicated to security and surveillance especially in military field, besides specialized techniques in thermal imaging for medical diagnostic and building structures and recently in energy savings and aerospace context. Till recently the security applications were mainly based on thermal imaging as surveillance and warning military systems. In all these applications the advent of room temperature, more reliable due to the coolers avoidance, low cost, and, overall, completely integrable with Silicon technology FPAs, especially designed and tailored for specific applications, smart sensors, has really been impacted with revolutionary and new ideas and system concepts in all the infrared fields, especially for security applications. Lastly, the advent of reliable Infrared Solid State Laser Sources, operating up to the Long Infrared Wavelength Band and the new emerging techniques in Far Infrared Submillimeter Terahertz Bands, has opened wide and new areas for developing new, advanced security systems. A review of all the items with evidence of the weak and the strong points of each item, especially considering possible future developments, will be reported and discussed. Carlo Corsi Copyright © 2012 Carlo Corsi. All rights reserved. Sun, 02 Dec 2012 14:33:53 +0000 http://www.hindawi.com/journals/aot/2012/278194/ Gold nanoparticles have been widely used during the past few years in various technical and biomedical applications. In particular, the resonance optical properties of nanometer-sized particles have been employed to design biochips and biosensors used as analytical tools. The optical properties of nonfunctionalized gold nanoparticles and core-gold nanoshells play a crucial role for the design of biosensors where gold surface is used as a sensing component. Gold nanoparticles exhibit excellent optical tunability at visible and near-infrared frequencies leading to sharp peaks in their spectral extinction. In this paper, we study how the optical properties of gold nanoparticles and core-gold nanoshells are changed as a function of different sizes, shapes, composition, and biomolecular coating with characteristic shifts towards the near-infrared region. We show that the optical tenability can be carefully tailored for particle sizes falling in the range 100–150 nm. The results should improve the design of sensors working at the detection limit. Mario D’Acunto, Davide Moroni, and Ovidio Salvetti Copyright © 2012 Mario D’Acunto et al. All rights reserved. Mon, 19 Nov 2012 18:22:25 +0000 http://www.hindawi.com/journals/aot/2012/765953/ The ever wide use of composite materials in the aeronautical industry has evidenced the need for development of ever more effective nondestructive evaluation methodologies in order to reduce rejected parts and to optimize production costs. Infrared thermography has been recently enclosed amongst the standardized non destructive testing techniques, but its usefulness needs still complete assessment since it can be employed in several different arrangements and for many purposes. In this work, the possibility to detect slag inclusions and porosity is analyzed with both lock-in themography and pulse thermography in the transmission mode. To this end, carbon-fiber-peinforced polymers different specimens are specifically fabricated of several different stacking sequences and with embedded slag inclusions and porosity percentages. As main results, both of the techniques are found definitely able to reveal the presence of the defects above mentioned. Moreover, these techniques could be considered complementary in order to better characterize the nature of the detected defects. C. Toscano, C. Meola, M. C. Iorio, and G. M. Carlomagno Copyright © 2012 C. Toscano et al. All rights reserved. Mon, 19 Nov 2012 13:30:24 +0000 http://www.hindawi.com/journals/aot/2012/926365/ We analyze some of the consequences of omitting series resistance in InAs/GaSb p-i-n T2SL photodiode dark current modelling, using simplified p-n junction model. Our considerations are limited to generation-recombination and diffusion-effective carrier lifetimes to show the possible scale of over- or underestimating photodiodes parameters in high-temperature region. As is shown, incorrect series resistance value might cause discrepancies in and 's estimations over one order of magnitude. Jarosław Wróbel, Piotr Martyniuk, and Antoni Rogalski Copyright © 2012 Jarosław Wróbel et al. All rights reserved. Wed, 14 Nov 2012 13:40:17 +0000 http://www.hindawi.com/journals/aot/2012/247070/ We review the temporal dynamics of the laser output spectrum and polarization state of 1.55 μm wavelength single-mode (SM) vertical-cavity surface-emitting lasers (VCSELs) induced by external optical beam injection. Injection of an external continuous-wave laser beam to a gain-switched SM VCSEL near the resonance wavelength corresponding to its main polarization-mode output was critical for improvement of its laser pulse generation characteristics, such as pulse timing-jitter reduction, linewidth narrowing, pulse amplitude enhancement, and pulse width shortening. Pulse injection of pulse width shorter than the cavity photon lifetime into the SM VCSEL in the orthogonal polarization direction with respect to its main polarization mode caused temporal delay of the polarization recovery after polarization switching (PS), and its delay was found to be the minimum at an optimized bias current. Polarization-mode bistability was observed even in the laser output of an SM VCSEL of a standard circularly cylindrical shape and used for all-optical flip-flop operations with set and reset injection pulses of very low pulse energy of order of the 3.5~4.5 fJ. Kyong Hon Kim, Seoung Hun Lee, and Vijay Manohar Deshmukh Copyright © 2012 Kyong Hon Kim et al. All rights reserved. Tue, 13 Nov 2012 14:22:15 +0000 http://www.hindawi.com/journals/aot/2012/925065/ Fiber optic components offer a competitive implementation for applications exploiting the millimeter-wave and THz regimes due to their capability for implementing broadband, compact, and cost-effective systems. In this paper, an outline of the latest technology developments and applications of fiber-optic-based technologies for the generation, transmission, and processing of high-frequency radio signals is provided. B. Vidal, T. Nagatsuma, N. J. Gomes, and T. E. Darcie Copyright © 2012 B. Vidal et al. All rights reserved. Sun, 11 Nov 2012 08:09:36 +0000 http://www.hindawi.com/journals/aot/2012/754546/ GaInNAs was proposed and created in 1995. It can be grown pseudomorphically on a GaAs substrate and is a light-emitting material with a bandgap energy that corresponds to near infrared. By combining GaInNAs with GaAs, an ideal band lineup for laser-diode application is achieved. This paper presents the reproducible growth of high-quality GaInNAs by molecular beam epitaxy. Examining the effect of nitrogen introduction and its correlation with impurity incorporation, we find that Al is unintentionally incorporated into the epitaxial layer even though the Al cell shutter is closed, followed by the concomitant incorporation of O and C. A gas-phase-scattering model can explain this phenomenon, suggesting that a large amount of N2 gas causes the scattering of residual Al atoms with occasional collisions resulting in the atoms being directed toward the substrate. Hence, the reduction of the sublimated Al beam during the growth period can suppress the incorporation of unintentional impurities, resulting in a highly pure epitaxial layer. Masahiko Kondow and Fumitaro Ishikawa Copyright © 2012 Masahiko Kondow and Fumitaro Ishikawa. All rights reserved. Thu, 08 Nov 2012 16:21:49 +0000 http://www.hindawi.com/journals/aot/2012/767836/ This paper introduces a preview of targeted current research on organic optofluidic materials and devices devoted to 3D photonics microresonators (MRs). First, such an approach takes advantage from a significant know-how on optical simulations of 3D spherical MRs by complementary and coupled ways based on electromagnetism and quantum mechanics principle. Such simulations have allowed to preset the quantization of whispering gallery modes (WGMs) and to define a new formulation of optical caustics in global 3D MRs cavities. Leaning from these simulations, an interdisciplinary approach has been achieved by combining microfluidics techniques and thin layer processes that allowed with flow rates control the realization of 3D droplets MRs of several tens of micrometers in radii. Finally, free-space optical characterizations have been performed on such 3D polymeric MRs by judicious protocols based, respectively, on a modified Raman spectroscopy laser excitation and an adequate direct beam waist optical coupling. Spectral analysis on such 3D MRs of various sizes confirms the excitation of the expected WGMs revealing free spectral range (FSR) and caustics values close to the analytical ones. David Pluchon, Nolwenn Huby, Alain Moréac, Pascal Panizza, and Bruno Bêche Copyright © 2012 David Pluchon et al. All rights reserved. Wed, 07 Nov 2012 09:11:29 +0000 http://www.hindawi.com/journals/aot/2012/720813/ The attention of the present paper is focused on the use of an infrared imaging device to monitor the thermal response of composite materials under cyclic bending. Three types of composites are considered including an epoxy matrix reinforced with either carbon fibres (CFRP) or glass fibres (GFRP) and a hybrid composite involving glass fibres and aluminium layers (FRML). The specimen surface, under bending, displays temperature variations pursuing the load variations with cooling down under tension and warming up under compression; such temperature variations are in agreement with the bending moment. It has been observed that the amplitude of temperature variations over the specimen surface depends on the material characteristics. In particular, the presence of a defect inside the material affects the temperature distribution with deviation from the usual bending moment trend. Carosena Meola, Giovanni Maria Carlomagno, Carmela Bonavolontà, and Massimo Valentino Copyright © 2012 Carosena Meola et al. All rights reserved. Tue, 23 Oct 2012 08:46:47 +0000 http://www.hindawi.com/journals/aot/2012/383212/ We propose an -cut LiNbO3 optical modulator using gap-embedded patch-antennas for wireless-over-fiber systems. The proposed device is composed of an array of narrow-gap-embedded patch-antennas and an optical waveguide located at the center of the gap without a buffer layer. The modulation efficiency of the proposed -cut LiNbO3 optical modulators was enhanced by 6 dB compared to the -cut LiTaO3-based devices. Yusuf Nur Wijayanto, Hiroshi Murata, Tetsuya Kawanishi, and Yasuyuki Okamura Copyright © 2012 Yusuf Nur Wijayanto et al. All rights reserved. Mon, 22 Oct 2012 10:08:40 +0000 http://www.hindawi.com/journals/aot/2012/808541/ Advanced IR emitters and sensors are under development for high detection probability, low false alarm rate, and identification capability of toxic gases. One of the most reliable techniques to identify the gas species is absorption spectroscopy, especially in the medium infrared spectral range, where most of existing toxic compounds exhibit their strongest rotovibrational absorption bands. Following the results obtained from simulations and analysis of expected absorption spectra, a compact nondispersive infrared multispectral system has been designed and developed for security applications. It utilizes a few square millimeters thermal source, a novel design multipass cell, and a smart architecture microbolometric sensor array coupled to a linear variable spectral filter to perform toxic gases detection and identification. This is done by means of differential absorption spectroscopic measurements in the spectral range of the midinfrared. Experimental tests for sensitivity and selectivity have been done with various chemical agents (CAs) gases and a multiplicity of vapour organic compounds (VOCs). Detection capability down to ppm has been demonstrated. Carlo Corsi, Andrea Dundee, Paolo Laurenzi, Nicola Liberatore, Domenico Luciani, Sandro Mengali, Angelo Mercuri, Andrea Pifferi, Mirko Simeoni, Gaetano Tosone, Roberto Viola, and Donatella Zintu Copyright © 2012 Carlo Corsi et al. All rights reserved. Thu, 18 Oct 2012 10:51:44 +0000 http://www.hindawi.com/journals/aot/2012/676785/ We demonstrate for the first time the continuous operation of a Bragg diffraction type electrooptic (EO) frequency shifter using a 16 GHz modulation signal. Because frequency shifting is based on the Bragg diffraction from an EO traveling phase grating (ETPG), this device can operate even in the millimeter-wave (>30 GHz) range or higher frequency range. The ETPG is generated based on the interaction between a modulation microwave guided by a microstrip line and a copropagating lightwave guided by a planner waveguide in a domain-engineered LiTaO3 EO crystal. In this work, the modulation power efficiency was improved by a factor of 11 compared with that of bulk devices by thinning the substrate so that the modulation electric field in the optical waveguide was enhanced. A shifting efficiency of 65% was achieved at the modulation power of 3 W. Shintaro Hisatake, Kenji Hattori, and Tadao Nagatsuma Copyright © 2012 Shintaro Hisatake et al. All rights reserved. Thu, 18 Oct 2012 08:10:05 +0000 http://www.hindawi.com/journals/aot/2012/792571/ The use of photonic heterodyne receivers based on semiconductor optical amplifiers to be used in imaging arrays at several GHz frequencies is evaluated. With this objective, a imaging array based on such photonic pixels has been fabricated and characterized. Each of the receiving optoelectronic pixels is composed of an antipodal linear tapered slot antenna (LTSA) that sends the received RF signal directly to the electrical port of a semiconductor opticalamplifier (SOA) acting as the optoelectronic mixer. Both the local oscillator (LO) and the intermediate frequency (IF) signals are directly distributed to/from the array pixels using fiber optics, that allows for remote LO generation and IF processing to recover the image. The results shown in this work demonstrate that the performances of the optoelectronic imaging array are similar to a reference all-electronic array, revealing the possibility of using this photonic architecture in future high-density, scalable, compact imaging arrays in microwave and millimeter wave ranges. Á. R. Criado, J. Montero-dePaz, C. de Dios, L. E. García, D. Segovia, and P. Acedo Copyright © 2012 Á. R. Criado et al. All rights reserved. Mon, 15 Oct 2012 15:43:47 +0000 http://www.hindawi.com/journals/aot/2012/385409/ Photonic technology offers an alternative implementation for the control of phased array antennas providing large time bandwidth products and low weight, flexible feeding networks. Measurements of an optical beamforming network for phased array antennas with fast beam steering operation for space scenarios are presented. Experimental results demonstrate fast beam steering between 4 and 8 GHz without beam squint. B. Vidal, T. Mengual, and J. Martí Copyright © 2012 B. Vidal et al. All rights reserved. Wed, 10 Oct 2012 08:30:40 +0000 http://www.hindawi.com/journals/aot/2012/918298/ We analyze the symmetry properties of the focal plane distribution when light is focused with an element characterized by a periodic angular dependent phase, sin () or cos (). The majority of wave aberrations can be described using the said phase function. The focal distribution is analytically shown to be a real function at odd values of m, which provides a simple technique for generating designed wave aberrations by means of binary diffractive optical elements. Such a possibility may prove useful in tight focusing, as the presence of definite wave aberrations allows the focal spot size to be decreased. The analytical computations are illustrated by the numerical simulation, which shows that by varying the radial parameters the focal spot configuration can be varied, whereas the central part symmetry is mainly determined by the parity of m: for even the symmetry order is 2m and for odd is m. Svetlana N. Khonina and Andrey V. Ustinov Copyright © 2012 Svetlana N. Khonina and Andrey V. Ustinov. All rights reserved. Tue, 02 Oct 2012 10:43:09 +0000 http://www.hindawi.com/journals/aot/2012/234321/ Recently, laser cutting is used in many industries. Generally, in laser cutting of metallic materials, suitable assist gas and its nozzle are needed to remove the molten metal. However, because of the gas nozzle should be set closer to the surface of a workpiece, existence of the nozzle seems to prevent laser cutting from being used flexible. Therefore, the new cutting process, Assist Gas Free laser cutting or AGF laser cutting, has been developed. In this process, the pressure at the bottom side of a workpiece is reduced by a vacuum pump, and the molten metal can be removed by the air flow caused by the pressure difference between both sides of the specimen. In this study, cutting properties of austenitic stainless steel by using AGF laser cutting with 2 kW CO2 laser were investigated. Laser power and cutting speed were varied in order to study the effect of these parameters on cutting properties. As a result, austenitic stainless steel could be cut with dross-free by AGF laser cutting. When laser power was 2.0 kW, cutting speed could be increased up to 100 mm/s, and kerf width at specimen surface was 0.28 mm. Hitoshi Ozaki, Yosuke Koike, Hiroshi Kawakami, and Jippei Suzuki Copyright © 2012 Hitoshi Ozaki et al. All rights reserved. Mon, 17 Sep 2012 13:56:40 +0000 http://www.hindawi.com/journals/aot/2012/639126/ We report the discovery of about 140 new energy levels of the neutral praseodymium atom, found by means of laser-induced fluorescence spectroscopy. Their energy has been determined with an uncertainty of 0.010 cm−1 using a wave number calibrated Fourier-transform spectrum. Zaheer Uddin, Driss El Bakkali, B. Gamper, Shamim Khan, Imran Siddiqui, G. H. Guthöhrlein, and L. Windholz Copyright © 2012 Zaheer Uddin et al. All rights reserved. Mon, 17 Sep 2012 08:32:57 +0000 http://www.hindawi.com/journals/aot/2012/234163/ Krassimir Panajotov, Rainer Michalzik, and Kent D. Choquette Copyright © 2012 Krassimir Panajotov et al. All rights reserved.