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Sample records for laser presentation material

  1. Laser material processing system

    DOEpatents

    Dantus, Marcos

    2015-04-28

    A laser material processing system and method are provided. A further aspect of the present invention employs a laser for micromachining. In another aspect of the present invention, the system uses a hollow waveguide. In another aspect of the present invention, a laser beam pulse is given broad bandwidth for workpiece modification.

  2. Lasers in materials processing

    SciTech Connect

    Davis, J.I.; Rockower, E.B.

    1981-01-01

    A status report on the uranium Laser Isotope Separation (LIS) Program at the Lawrence Livermore National Laboratory is presented. Prior to this status report, process economic analysis is presented so as to understand how the unique properties of laser photons can be best utilized in the production of materials and components despite the high cost of laser energy. The characteristics of potential applications that are necessary for success are identified, and those factors that have up to now frustrated attempts to find commercially viable laser induced chemical and physical process for the production of new or existing materials are pointed out.

  3. Laser speckle micro rheology for micro-mechanical mapping of bio-materials (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Hajjarian Kashany, Zeinab; Ahn, Shawn; Tavakoli Nia, Hadi; Tshikudi, Diane M.; Grodzinsky, Alan; Jain, Rakesh K.; Nadkarni, Seemantini K.

    2016-03-01

    Laser speckle Micro-rheology (LSM) is a novel optical tool for evaluating the viscoelastic properties of biomaterials. In LSM, a laser beam illuminates the specimen and scattered rays are collected through an objective by a high-speed CMOS camera. The self-interference of light rays forms a fluctuating speckle pattern captured by the CMOS sensor. Spatio-temporal correlation analysis of speckle images provides the intensity autocorrelation function, g2(t), for individual pixels. Next, the mean square displacements (MSD) of Brownian particles are deduced and substituted in the generalized Stokes-Einstein relation (GSER) to yield a 2D map of viscoelastic modulus, |G*(ω)|. To compare the accuracy, sensitivity, and dynamic range of LSM measurements with standard mechanical testing methods, homogeneous polyethylene glycol (PEG), agarose, and polyacrylamide (PA) gels, of assorted viscoelastic properties were fabricated and evaluated using LSM, shear rheology, and indentation-mode atomic force microscopy (AFM). Results showed a statistically significant, strong correlation between G* values measured by LSM and shear rheology (R=0.94, p<5x10-6) (|G*|: 30 Pa - 30 kPa at ω = 1 Hz). Likewise, strong correlation was observed between G* values measured by LSM and indentation moduli of AFM (R=0.94, p,0.05). Next, polyacrylamide substrates with micro-scale stiffness patterns were tested using LSM. The reconstructed |G*| maps illustrated the high sensitivity of LSM in resolving mechanical heterogeneities below 100 microns. These findings demonstrate the competent accuracy and sensitivity of LSM measurements. Moreover, the non-contact nature of LSM provides a major advantage over mechanical tests, making it suitable for in vivo studies in future.

  4. Modern solid state laser materials

    SciTech Connect

    Krupke, W.F.

    1984-06-20

    This document contains visual aids used in an invited talk entitled Modern Solid State Laser Materials, presented at the Conference on Lasers and Electro-Optics (CLEO) held in Anaheim, California, on June 20, 1984. Interest at LLNL in solid state lasers focuses on evaluating the potential of solid state laser media for high average power applications, including inertial fusion power production. This talk identifies the relevant bulk material parameters characterizing average power capacity and uses chromium and neodymium co-doped gadolinium scandium gallium garnet (Nd:Cr:GSGG) as an example of a laser material with improved laser properties relative to Nd:YAG (plausible large-scale growth, more efficient spectral coupling to xenon flashlamp radiation, reduced stimulated emission cross section, adequate thermal shock and optical damage threshold parameters, etc.). Recently measured spectroscopic, kinetic, and thermo-mechanical properties of Nd:Cr:GSGG are given.

  5. Femtosecond laser materials processing

    SciTech Connect

    Stuart, B. C., LLNL

    1998-06-02

    Femtosecond lasers enable materials processing of most any material with extremely high precision and negligible shock or thermal loading to the surrounding area Applications ranging from drilling teeth to cutting explosives to making high-aspect ratio cuts in metals with no heat-affected zone are made possible by this technology For material removal at reasonable rates, we developed a fully computer-controlled 15-Watt average power, 100-fs laser machining system.

  6. Femtosecond laser materials processing

    SciTech Connect

    Stuart, B

    1998-08-05

    Femtosecond lasers enable materials processing of most any material with extremely high precision and negligible shock or thermal loading to the surrounding area. Applications ranging from drilling teeth to cutting explosives to precision cuts in composites are possible by using this technology. For material removal at reasonable rates, we have developed a fully computer-controlled 15-Watt average power, 100-fs laser machining system.

  7. Ceramic Laser Materials

    SciTech Connect

    Soules, T F; Clapsaddle, B J; Landingham, R L; Schaffers, K I

    2005-02-15

    Transparent ceramic materials have several major advantages over single crystals in laser applications, not the least of which is the ability to make large aperture parts in a robust manufacturing process. After more than a decade of working on making transparent YAG:Nd, Japanese workers have recently succeeded in demonstrating samples that performed as laser gain media as well as their single crystal counterparts. Since then several laser materials have been made and evaluated. For these reasons, developing ceramic laser materials is the most exciting and futuristic materials topic in today's major solid-state laser conferences. We have established a good working relationship with Konoshima Ltd., the Japanese producer of the best ceramic laser materials, and have procured and evaluated slabs designed by us for use in our high-powered SSHCL. Our measurements indicate that these materials will work in the SSHCL, and we have nearly completed retrofitting the SSHCL with four of the largest transparent ceramic YAG:Nd slabs in existence. We have also begun our own effort to make this material and have produced samples with various degrees of transparency/translucency. We are in the process of carrying out an extensive design-of-experiments to establish the significant process variables for making transparent YAG. Finally because transparent ceramics afford much greater flexibility in the design of lasers, we have been exploring the potential for much larger apertures, new materials, for example for the Mercury laser, other designs for SSHL, such as, edge pumping designs, slabs with built in ASE suppression, etc. This work has just beginning.

  8. Laser And Nonlinear Optical Materials For Laser Remote Sensing

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.

    2005-01-01

    NASA remote sensing missions involving laser systems and their economic impact are outlined. Potential remote sensing missions include: green house gasses, tropospheric winds, ozone, water vapor, and ice cap thickness. Systems to perform these measurements use lanthanide series lasers and nonlinear devices including second harmonic generators and parametric oscillators. Demands these missions place on the laser and nonlinear optical materials are discussed from a materials point of view. Methods of designing new laser and nonlinear optical materials to meet these demands are presented.

  9. Materials micro-processing using femtosecond lasers

    NASA Astrophysics Data System (ADS)

    Dabu, R.; Zamfirescu, M.; Anghel, I.; Jipa, F.

    2013-06-01

    Nonlinear optical phenomena which dominate the interaction of tightly focused femtosecond laser beams with materials are discussed. Different femtosecond laser based techniques for material processing such as laser ablation, two-photon photo-polymerization, and material surface nano-structuring are described. For the computer controlled micro-processing of materials, near-infrared Ti:sapphire femtosecond lasers, with nano-Joule/micro-Joule pulse energy, were coupled with direct laser writing workstations. Laser fabricated micro-nanostructures and their applications are presented.

  10. Present status and future aspects of high-power diode laser materials processing under the view of a German national research project

    NASA Astrophysics Data System (ADS)

    Bachmann, Friedrich G.

    2000-06-01

    High power diode lasers from a few Watts up to several Kilowatts have entered industrial manufacturing environment for materials processing applications. The technology has proven to show unique features, e.g. high efficiency, small size, low energy consumption and high reliability. In the first part of this paper a short description of state-of- the-art high power diode laser technology and applications is provided and the benefits and restrictions of this laser technology will be evaluated. For large scale penetration into the manufacture market, the restrictions, especially the rather poor beam quality of high power diode lasers compared to conventional lasers have to be overcome. Also, the specialities of the high power diode lasers, i.e. their modular structure and their extremely small size have to be translated into laser manufacturing technology. The further improvement of high power diode lasers as well as the development of new diode laser specific manufacturing technologies are the essential topics of a National German Minister Priority Project entitled 'Modular Diode Laser Beam Tools': 22 Partners from industry and institutions, 4 semiconductor experts, 5 laser manufacturers and 14 applicants are working together in frame of this project to work out and transfer a joint strategy and system technology to the benefits of the future of high power diode laser technology. The goals, the structure and the work of this project will be described in the second part of this paper.

  11. New laser materials for laser diode pumping

    NASA Technical Reports Server (NTRS)

    Jenssen, H. P.

    1990-01-01

    The potential advantages of laser diode pumped solid state lasers are many with high overall efficiency being the most important. In order to realize these advantages, the solid state laser material needs to be optimized for diode laser pumping and for the particular application. In the case of the Nd laser, materials with a longer upper level radiative lifetime are desirable. This is because the laser diode is fundamentally a cw source, and to obtain high energy storage, a long integration time is necessary. Fluoride crystals are investigated as host materials for the Nd laser and also for IR laser transitions in other rare earths, such as the 2 micron Ho laser and the 3 micron Er laser. The approach is to investigate both known crystals, such as BaY2F8, as well as new crystals such as NaYF8. Emphasis is on the growth and spectroscopy of BaY2F8. These two efforts are parallel efforts. The growth effort is aimed at establishing conditions for obtaining large, high quality boules for laser samples. This requires numerous experimental growth runs; however, from these runs, samples suitable for spectroscopy become available.

  12. Laser Material Processing for Microengineering Applications

    NASA Technical Reports Server (NTRS)

    Helvajian, H.

    1995-01-01

    The processing of materials via laser irradiation is presented in a brief survey. Various techniques currently used in laser processing are outlined and the significance to the development of space qualified microinstrumentation are identified. In general the laser processing technique permits the transferring of patterns (i.e. lithography), machining (i.e. with nanometer precision), material deposition (e.g., metals, dielectrics), the removal of contaminants/debris/passivation layers and the ability to provide process control through spectroscopy.

  13. Laser applications in machining slab materials

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoping

    1990-10-01

    Since the invention of the laser back in 1960, laser technology has been extensively applied in many fields of science and technology. These has been a history of nearly two decades of using lasers as an energy source in machining materials, such as cutting, welding, ruling and boring, among other operations. With the development of flexible automation in production, the advantages of laser machining have has grown more and more obvious. The combination of laser technology and computer science further promotes the enhancement and upgrading of laser machining and related equipment. At present, many countries are building high quality laser equipment for machining slab materials, such as the Coherent and Spectra Physics corporations in the United States, the Trumpf Corporation in West Germany, the Amada Corporation in Japan, and the Bystronic Corporation in Switzerland, among other companies.

  14. Femtosecond Laser Interaction with Energetic Materials

    SciTech Connect

    Roos, E; Benterou, J; Lee, R; Roeske, F; Stuart, B

    2002-03-25

    Femtosecond laser ablation shows promise in machining energetic materials into desired shapes with minimal thermal and mechanical effects to the remaining material. We will discuss the physical effects associated with machining energetic materials and assemblies containing energetic materials, based on experimental results. Interaction of ultra-short laser pulses with matter will produce high temperature plasma at high-pressure which results in the ablation of material. In the case of energetic material, which includes high explosives, propellants and pyrotechnics, this ablation process must be accomplished without coupling energy into the energetic material. Experiments were conducted in order to characterize and better understand the phenomena of femtosecond laser pulse ablation on a variety of explosives and propellants. Experimental data will be presented for laser fluence thresholds, machining rates, cutting depths and surface quality of the cuts.

  15. Laser cutting plastic materials

    SciTech Connect

    Van Cleave, R.A.

    1980-08-01

    A 1000-watt CO/sub 2/ laser has been demonstrated as a reliable production machine tool for cutting of plastics, high strength reinforced composites, and other nonmetals. More than 40 different plastics have been laser cut, and the results are tabulated. Applications for laser cutting described include fiberglass-reinforced laminates, Kevlar/epoxy composites, fiberglass-reinforced phenolics, nylon/epoxy laminates, ceramics, and disposable tooling made from acrylic.

  16. Laser Materials Processing for NASA's Aerospace Structural Materials

    NASA Technical Reports Server (NTRS)

    Nagarathnam, Karthik; Hunyady, Thomas A.

    2001-01-01

    Lasers are useful for performing operations such as joining, machining, built-up freeform fabrication, and surface treatment. Due to the multifunctional nature of a single tool and the variety of materials that can be processed, these attributes are attractive in order to support long-term missions in space. However, current laser technology also has drawbacks for space-based applications. Specifically, size, power efficiency, lack of robustness, and problems processing highly reflective materials are all concerns. With the advent of recent breakthroughs in solidstate laser (e.g., diode-pumped lasers) and fiber optic technologies, the potential to perform multiple processing techniques in space has increased significantly. A review of the historical development of lasers from their infancy to the present will be used to show how these issues may be addressed. The review will also indicate where further development is necessary to realize a laser-based materials processing capability in space. The broad utility of laser beams in synthesizing various classes of engineering materials will be illustrated using state-of-the art processing maps for select lightweight alloys typically found on spacecraft. Both short- and long-term space missions will benefit from the development of a universal laser-based tool with low power consumption, improved process flexibility, compactness (e.g., miniaturization), robustness, and automation for maximum utility with a minimum of human interaction. The potential advantages of using lasers with suitable wavelength and beam properties for future space missions to the moon, Mars and beyond will be discussed. The laser processing experiments in the present report were performed using a diode pumped, pulsed/continuous wave Nd:YAG laser (50 W max average laser power), with a 1064 nm wavelength. The processed materials included Ti-6AI-4V, Al-2219 and Al-2090. For Phase I of this project, the laser process conditions were varied and optimized

  17. Laser detection of material thickness

    DOEpatents

    Early, James W.

    2002-01-01

    There is provided a method for measuring material thickness comprising: (a) contacting a surface of a material to be measured with a high intensity short duration laser pulse at a light wavelength which heats the area of contact with the material, thereby creating an acoustical pulse within the material: (b) timing the intervals between deflections in the contacted surface caused by the reverberation of acoustical pulses between the contacted surface and the opposite surface of the material: and (c) determining the thickness of the material by calculating the proportion of the thickness of the material to the measured time intervals between deflections of the contacted surface.

  18. Laser cutting of energetic materials

    SciTech Connect

    Rivera, T.; Muenchausen, R.; Sanchez, J.

    1998-12-01

    The authors have demonstrated the feasibility of safely and efficiently cutting and drilling metal cases containing a variety of high explosives (HE) using a Nd:YAG laser. Spectral analysis of the optical emission, occurring during the laser-induced ablation process, is used to identify the removed material. By monitoring changes in the optical emission during the cutting process, the metal-He interface can be observed in real time and the cutting parameters adjusted accordingly. For cutting the HE material itself, the authors have demonstrated that this can be safely and efficiently accomplished by means of a ultraviolet (UV) laser beam obtained from the same Nd:YAG laser using the third or fourth harmonics. They are currently applying this technology to UXO identification and ordnance demilitarization.

  19. Femtosecond laser materials processing

    SciTech Connect

    Stuart, B.C.

    1997-02-01

    The use femtosecond pulses for materials processing results in very precise cutting and drilling with high efficiency. Energy deposited in the electrons is not coupled into the bulk during the pulse, resulting in negligible shock or thermal loading to adjacent areas.

  20. Laser-Material Interaction of Powerful Ultrashort Laser Pulses

    SciTech Connect

    Komashko, A

    2003-01-06

    Laser-material interaction of powerful (up to a terawatt) ultrashort (several picoseconds or shorter) laser pulses and laser-induced effects were investigated theoretically in this dissertation. Since the ultrashort laser pulse (USLP) duration time is much smaller than the characteristic time of the hydrodynamic expansion and thermal diffusion, the interaction occurs at a solid-like material density with most of the light energy absorbed in a thin surface layer. Powerful USLP creates hot, high-pressure plasma, which is quickly ejected without significant energy diffusion into the bulk of the material, Thus collateral damage is reduced. These and other features make USLPs attractive for a variety of applications. The purpose of this dissertation was development of the physical models and numerical tools for improvement of our understanding of the process and as an aid in optimization of the USLP applications. The study is concentrated on two types of materials - simple metals (materials like aluminum or copper) and wide-bandgap dielectrics (fused silica, water). First, key physical phenomena of the ultrashort light interaction with metals and the models needed to describe it are presented. Then, employing one-dimensional plasma hydrodynamics code enhanced with models for laser energy deposition and material properties at low and moderate temperatures, light absorption was self-consistently simulated as a function of laser wavelength, pulse energy and length, angle of incidence and polarization. Next, material response on time scales much longer than the pulse duration was studied using the hydrocode and analytical models. These studies include examination of evolution of the pressure pulses, effects of the shock waves, material ablation and removal and three-dimensional dynamics of the ablation plume. Investigation of the interaction with wide-bandgap dielectrics was stimulated by the experimental studies of the USLP surface ablation of water (water is a model of

  1. Millisecond laser machining of transparent materials assisted by nanosecond laser.

    PubMed

    Pan, Yunxiang; Zhang, Hongchao; Chen, Jun; Han, Bing; Shen, Zhonghua; Lu, Jian; Ni, Xiaowu

    2015-01-26

    A new form of double pulse composed of a nanosecond laser and a millisecond laser is proposed for laser machining transparent materials. To evaluate its advantages and disadvantages, experimental investigations are carried out and the corresponding results are compared with those of single millisecond laser. The mechanism is discussed from two aspects: material defects and effects of modifications induced by nanosecond laser on thermal stress field during millisecond laser irradiation. It is shown that the modifications of the sample generated by nanosecond laser improves the processing efficiency of subsequent millisecond laser, while limits the eventual size of modified region.

  2. Possibilities of Laser Processing of Paper Materials

    NASA Astrophysics Data System (ADS)

    Stepanov, Alexander; Saukkonen, Esa; Piili, Heidi

    Nowadays, lasers are applied in many industrial processes: the most developed technologies include such processes as laser welding, hybrid welding, laser cutting of steel, etc. In addition to laser processing of metallic materials, there are also many industrial applications of laser processing of non-metallic materials, like laser welding of polymers, laser marking of glass and laser cutting of wood-based materials. It is commonly known that laser beam is suitable for cutting of paper materials as well as all natural wood-fiber based materials. This study reveals the potential and gives overview of laser application in processing of paper materials. In 1990's laser technology increased its volume in papermaking industry; lasers at paper industry gained acceptance for different perforating and scoring applications. Nowadays, with reduction in the cost of equipment and development of laser technology (especially development of CO2 technology), laser processing of paper material has started to become more widely used and more efficient. However, there exists quite little published research results and reviews about laser processing of paper materials. In addition, forest industry products with pulp and paper products in particular are among major contributors for the Finnish economy with 20% share of total exports in the year 2013. This has been the standpoint of view and motivation for writing this literature review article: when there exists more published research work, knowledge of laser technology can be increased to apply it for processing of paper materials.

  3. Heat accumulation during pulsed laser materials processing.

    PubMed

    Weber, Rudolf; Graf, Thomas; Berger, Peter; Onuseit, Volkher; Wiedenmann, Margit; Freitag, Christian; Feuer, Anne

    2014-05-01

    Laser materials processing with ultra-short pulses allows very precise and high quality results with a minimum extent of the thermally affected zone. However, with increasing average laser power and repetition rates the so-called heat accumulation effect becomes a considerable issue. The following discussion presents a comprehensive analytical treatment of multi-pulse processing and reveals the basic mechanisms of heat accumulation and its consequence for the resulting processing quality. The theoretical findings can explain the experimental results achieved when drilling microholes in CrNi-steel and for cutting of CFRP. As a consequence of the presented considerations, an estimate for the maximum applicable average power for ultra-shorts pulsed laser materials processing for a given pulse repetition rate is derived.

  4. Novel materials for laser refrigeration

    SciTech Connect

    Hehlen, Markus P

    2009-01-01

    The status of optical refrigeration of rare-earth-doped solids is reviewed, and the various factors that limit the performance of current laser-cooling materials are discussed. Efficient optical refrigeration is possible in materials for which {Dirac_h}{omega}{sub max} < E{sub p}/8, where {Dirac_h}{omega}{sub max} is the maximum phonon energy of the host material and E{sub p} is the pump energy of the rare-earth dopant. Transition-metal and OH{sup -}impurities at levels >100 ppb are believed to be the main factors for the limited laser-cooling performance in current materials. The many components of doped ZBLAN glass pose particular processing challenges. Binary fluoride glasses such as YF{sub 3}-LiF are considered as alternatives to ZBLAN. The crystalline system KPb{sub 2}CI{sub 5} :Dy{sup 3+} is identified as a prime candidate for high-efficiency laser cooling.

  5. Precise micromachining of materials using femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Garasz, K.; Tański, M.; Barbucha, R.; Kocik, M.

    2015-06-01

    We present the results of the experimental parametric study on efficiency, accuracy and quality of femtosecond laser micromachining of different materials. The laser micromachining process was performed with a solid-state Yb:KYW laser. The laser generates 500 fs pulses of three different wavelengths, repetition rate from 100 to 900 kHz and output power up to 50 W. This allows to perform a complex research for a wide range of parameters and materials. Laser micromachining is a process based on a laser ablation phenomenon, i.e. total evaporation of material from the target surface during laser irradiation. It is the most precise method of material removal. Applying a femtosecond laser in the process, allows the use of ultra short pulses, with a duration of 10-15 seconds, while maintaining a high laser power. The concentration of energy within a single pulse is sufficiently high to cause the detachment of particles from the irradiated target without any thermal interactions with the surrounding material. Therefore, the removal of the material occurs only in the laser focus. This allows to avoid most of the unwanted effects of the heat affected zone (HAZ). It has been established, that the quality of laser ablation process using femtosecond pulses is much higher than while using the long pulsed lasers (i.e. nanosecond). The use of femtosecond laser pulses creates therefore an attractive opportunity for high quality micromachining of many groups of materials.

  6. Bulk Laser Material Modification: Towards a Kerfless Laser Wafering Process

    NASA Astrophysics Data System (ADS)

    LeBeau, James

    Due to the ever increasing relevance of finer machining control as well as necessary reduction in material waste by large area semiconductor device manufacturers, a novel bulk laser machining method was investigated. Because the cost of silicon and sapphire substrates are limiting to the reduction in cost of devices in both the light emitting diode (LED) and solar industries, and the present substrate wafering process results in >50% waste, the need for an improved ingot wafering technique exists. The focus of this work is the design and understanding of a novel semiconductor wafering technique that utilizes the nonlinear absorption properties of band-gapped materials to achieve bulk (subsurface) morphological changes in matter using highly focused laser light. A method and tool was designed and developed to form controlled damage regions in the bulk of a crystalline sapphire wafer leaving the surfaces unaltered. The controllability of the subsurface damage geometry was investigated, and the effect of numerical aperture of the focusing optic, energy per pulse, wavelength, and number of pulses was characterized for a nanosecond pulse length variable wavelength Nd:YAG OPO laser. A novel model was developed to describe the geometry of laser induced morphological changes in the bulk of semiconducting materials for nanosecond pulse lengths. The beam propagation aspect of the model was based on ray-optics, and the full Keldysh multiphoton photoionization theory in conjuncture with Thornber's and Drude's models for impact ionization were used to describe high fluence laser light absorption and carrier generation ultimately resulting in permanent material modification though strong electron-plasma absorption and plasma melting. Although the electron-plasma description of laser damage formation is usually reserved for extremely short laser pulses (<20 ps), this work shows that it can be adapted for longer pulses of up to tens of nanoseconds. In addition to a model

  7. Industrial Materials Processing Laser Markets

    NASA Astrophysics Data System (ADS)

    Followwill, Dorman

    1989-03-01

    The way I would like to handle this morning is first, to give you an overview before I put anything up in terms of slides. An overview of the study that we produced a couple of months ago. It is entitled "Industrial Materials Processing Laser Markets", and if you want information on that particular study, then you can speak with me at the coffee break.

  8. The reverse laser drilling of transparent materials

    NASA Technical Reports Server (NTRS)

    Anthony, T. R.; Lindner, P. A.

    1980-01-01

    Within a limited range of incident laser-beam intensities, laser drilling of a sapphire wafer initiates on the surface of the wafer where the laser beam exits and proceeds upstream in the laser beam to the surface where the laser beam enters the wafer. This reverse laser drilling is the result of the constructive interference between the laser beam and its reflected component on the exit face of the wafer. Constructive interference occurs only at the exit face of the sapphire wafer because the internally reflected laser beam suffers no phase change there. A model describing reverse laser drilling predicts the ranges of incident laser-beam intensity where no drilling, reverse laser drilling, and forward laser drilling can be expected in various materials. The application of reverse laser drilling in fabricating feed-through conductors in silicon-on-sapphire wafers for a massively parallel processer is described.

  9. Present and Future of Laser Accelerator

    NASA Astrophysics Data System (ADS)

    Kitagawa, Yoneyoshi

    Plasma is an attractive medium for the advanced accelerator. When combined with an ultra-intense laser, it makes the acceleration field of one thousand times the current microwave accelerators. The major fields, which require now the particle accelerator, are not the high energy physics, but the medical, industrial and low energy material fields. So we need to concentrate the effort to develop the low to medium energy, but much compact accelerators on table. Last year, it has produced 200 MeV electrons from a 2 mm-long plasma. This corresponds to 100 GV/m. In these 10 years, the laser accelerator research has advanced the electron gain of from 22 MeV to 200 MeV. On the other hand, a glass capillary has this year succeeded in making the plasma length, the acceleration length, from 2 mm to 10 mm. This will be a breakthrough to the second generation of the advanced accelerator development. The new field is beginning to grow from the quantum electronics, plasma science, beam and accelerator physics.

  10. Review of Tm and Ho Materials; Spectroscopy and Lasers

    NASA Technical Reports Server (NTRS)

    Walsh, Brian M.

    2008-01-01

    A review of Tm and Ho materials is presented, covering some fundamental aspects on the spectroscopy and laser dynamics in both single and co-doped systems. Following an introduction to 2- m lasers, applications and historical development, the physics of quasi-four level lasers, energy transfer and modeling are discussed in some detail. Recent developments in using Tm lasers to pump Ho lasers are discussed, and seen to offer some advantages over conventional Tm:Ho lasers. This article is not intended as a complete review, but as a primer for introducing concepts and a resource for further study.

  11. Properties of Optical and Laser-Related Materials: A Handbook

    NASA Astrophysics Data System (ADS)

    Nikogosyan, David N.

    2003-05-01

    Properties of Optical and Laser-Related Materials-A Handbook offers the reader a self-contained, concise and up-to-date collection of the key properties of 125 of the most common and important optical materials used in modern optics, laser physics and technology, spectroscopy and laser spectroscopy, nonlinear optics, quantum electronics and laser applications. This comprehensive volume presents not only the classical properties but also those that have appeared in the three decades since the invention of the laser. The presentation of the material is given in a clear tabular form with more than 1000 references. A wide variety of readers, ranging from workers in both industry and academia, to lecturers and students at postgraduate and undergraduate levels, will find Properties of Optical and Laser-Related Materials-A Handbook an invaluable resource.

  12. Mid-infrared solid-state lasers and laser materials

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Byvik, Charles E.

    1988-01-01

    An account is given of NASA-Langley's objectives for the development of advanced lasers and laser materials systems applicable to remote sensing in the mid-IR range. Prominent among current concerns are fiber-optic spectroscopy, eye-safe solid-state lasers for both Doppler sensing and mid-IR wavelength-generation laser pumping, and nonlinear optics generating tunable mid-IR radiation. Ho:YAG lasers are noted to exhibit intrinsic advantages for the desired applications, and are pumpable by GaAlAs laser diodes with a quantum efficiency approaching 2.

  13. Laser coupling effects on structural material under different surface conditions

    NASA Astrophysics Data System (ADS)

    Feng, Guobing; Wei, Chenghua; Wu, Lixiong; Chen, Linzhu; Lin, Xinwei; Zhang, Jianmin; Ma, Zhiliang

    2013-05-01

    The laser coupling effect of material is a fundamental factor to influence laser interaction with matter. The coupling coefficient, which is the material absorptance of the input laser energy, depends on the surface conditions of materials, such as temperature, incident angle, surface airflow, oxidizing environment, and so on. To measure the laser coupling characteristics of materials, two typical online measuring apparatuses were developed in our laboratory. One is based on a conjugated hemi-ellipsoidal reflectometer, which is suitable to measure the laser coupling coefficients of different temperature in vacuum and air environments. The other is based on an integrating sphere and a simple airflow simulator, which can be applied to online measure the laser absorptance of materials subjected to surface airflow. The laser coupling effects on two types of structural materials, which are alloy steels and composite materials, are given in this paper. With the conjugated ellipsoidal reflectometer, the laser coupling effects on a typical alloy steel are investigated in different temperatures under the vacuum and air environment, and the experimental results are analyzed. According the results, metal oxidization plays a key role in the laser coupling enhancement effects. Especially, when the metal is subjected to high power laser irradiation in the high subsonic airflow, metal oxidization which is an exothermic reaction enhances the laser damage effect and the convective heat loss is negligible. Finally, the laser coupling effects on a typical composite material subjected to airflow are studied by using the integrating sphere with an airflow simulator, and the experimental results of laser absorptance during the laser ablation are presented.

  14. Advanced laser processing of glass materials

    NASA Astrophysics Data System (ADS)

    Sugioka, Koji; Obata, Kotaro; Cheng, Ya; Midorikawa, Katsumi

    2003-09-01

    Three kinds of advanced technologies using lasers for glass microprocessing are reviewed. Simultaneous irradiation of vacuum ultraviolet (VUV) laser beam, which possesses extremely small laser fluence, with ultraviolet (UV) laser achieves enhanced high surface and edge quality ablation in fused silica and other hard materials with little debris deposition as well as high-speed and high-efficiency refractive index modification of fused silica (VUV-UV multiwavelength excitation processing). Metal plasma generated by the laser beam effectively assists high-quality ablation of transparent materials, resulting in surface microstructuring, high-speed holes drilling, crack-free marking, color marking, painting and metal interconnection for the various kinds of glass materials (laser-induced plasma-assisted ablation (LIPAA)). In the meanwhile, a nature of multiphoton absorption of femtosecond laser by transparent materials realizes fabrication of true three-dimensional microstructures embedded in photosensitive glass.

  15. Challenge to advanced materials processing with lasers in Japan

    NASA Astrophysics Data System (ADS)

    Miyamoto, Isamu

    2003-02-01

    Japan is one of the most advanced countries in manufacturing technology, and lasers have been playing an important role for advancement of manufacturing technology in a variety of industrial fields. Contribution of laser materials processing to Japanese industry is significant for both macroprocessing and microprocessing. The present paper describes recent trend and topics of industrial applications in terms of the hardware and the software to show how Japanese industry challenges to advanced materials processing using lasers, and national products related to laser materials processing are also briefly introduced.

  16. Transient Infrared Measurement of Laser Absorption Properties of Porous Materials

    NASA Astrophysics Data System (ADS)

    Marynowicz, Andrzej

    2016-06-01

    The infrared thermography measurements of porous building materials have become more frequent in recent years. Many accompanying techniques for the thermal field generation have been developed, including one based on laser radiation. This work presents a simple optimization technique for estimation of the laser beam absorption for selected porous building materials, namely clinker brick and cement mortar. The transient temperature measurements were performed with the use of infrared camera during laser-induced heating-up of the samples' surfaces. As the results, the absorbed fractions of the incident laser beam together with its shape parameter are reported.

  17. Laser Ignition of Energetic Materials Workshop

    NASA Astrophysics Data System (ADS)

    Devries, Nora M.; Oreilly, John J.; Forch, Brad E.

    1993-11-01

    Lasers inherently possess many desirable attributes making them excellent igniters for a wide range of energetic materials such as pyrotechnics, explosives, and gun propellants. Lasers can be made very small, have modest powereD requirements, are invulnerable to external stimuli, are very reliable, and can deliver radiative energy to remote locations through optical fibers. Although the concept of using lasers for the initiation of energetic materials is not new, successful integration of laser technology into military systems has the potential to provide significant benefits. In order to efficiently expedite the evolution of the laser ignition technology for military applications, it was desirable to coordinate the effort with the JANNAF combustion community. The laser ignition of Energetic Materials Workshop was originated by Brad Forch, Austin Barrows, Richard Beyer and Arthur Cohen of the Army Research Laboratory (ARL).

  18. Lasant Materials for Blackbody-Pumped Lasers

    NASA Technical Reports Server (NTRS)

    Deyoung, R. J. (Editor); Chen, K. Y. (Editor)

    1985-01-01

    Blackbody-pumped solar lasers are proposed to convert sunlight into laser power to provide future space power and propulsion needs. There are two classes of blackbody-pumped lasers. The direct cavity-pumped system in which the lasant molecule is vibrationally excited by the absorption of blackbody radiation and laser, all within the blackbody cavity. The other system is the transfer blackbody-pumped laser in which an absorbing molecule is first excited within the blackbody cavity, then transferred into a laser cavity when an appropriate lasant molecule is mixed. Collisional transfer of vibrational excitation from the absorbing to the lasing molecule results in laser emission. A workshop was held at NASA Langley Research Center to investigate new lasant materials for both of these blackbody systems. Emphasis was placed on the physics of molecular systems which would be appropriate for blackbody-pumped lasers.

  19. Optofluidic lasers and their applications in bioanalysis (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Fan, Xudong

    2016-03-01

    The optofluidic laser is an emerging technology that integrates microfluidics, miniaturized laser cavity, and laser gain medium in liquid. It is unique due to its biocompatibility, thus can be used for unconventional bioanalysis, in which biointeraction or process takes place within the optical cavity mode volume. Rather than using fluorescence, the optofluidic laser based detection employs laser emission, i.e., stimulated emission, as the sensing signal, which takes advantage of optical amplification provided by the laser cavity to achieve much higher sensitivity. In this presentation, I will first introduce the concept of optofluidic laser based bioanalysis. Then I will discuss each of the three components (cavity, gain medium, and fluidics) of the optofluidic laser and describe how to use the optofluidic laser in bioanalysis at the molecular, cellular, and tissue level. Finally, I will discuss future research and application directions.

  20. New laser materials: Final report

    SciTech Connect

    Not Available

    1986-10-01

    In the Interim Report No. 1, it was reported that the fluorescence lifetime (greater than or equal to 750..mu..s) in Nd doped Y(PO/sub 3/)/sub 3/ was longer by a factor of three as compared to YAG. This means potentially three times as much energy storage and consequently more efficient for flashlamp pumping. It also makes diode pumping easier. In addition, since the Y site is octahedrally coordinated, there is a possibility of energy transfer using Cr as the sensitizing element. As suggested by W. Krupke, we decided to explore the trivalent cation metaphosphates systematically. The compounds investigated can be represented by the general formula A(PO/sub 3/)/sub 3/ where A = Y, Lu, In, Sc, GA and Al. The object is to study the fluorescence characteristics of Nd and Cr as well as the effectiveness of energy transfer from Cr to Nd. In addition, we also investigated other possible laser host crystals, notably CaMgSi/sub 2/O/sub 6/ (diopside), LaBO/sub 3/ and La(BO/sub 2/)/sub 3/. Results on these materials will also be discussed.

  1. Multiphysical Simulation of Laser Material Processing

    NASA Astrophysics Data System (ADS)

    Otto, Andreas; Koch, Holger; Vazquez, Rodrigo Gomez

    Within this paper a multiphysical simulation model is presented that is capable for simulating a wide range of laser processes like e.g. laser beam welding, brazing, cutting, drilling or ablation. Some important aspects of the model are explained more in detail and results from test cases are compared with analytical solutions revealing the high accuracy of the model. Finally exemplary results from process simulations on laser beam remote cutting of steel and laser beam scribing of silicon wafers are given.

  2. Efficiency of Nd laser materials with laser diode pumping

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Cross, Patricia L.; Skolaut, Milton W., Jr.; Storm, Mark E.

    1990-01-01

    For pulsed laser-diode-pumped lasers, where efficiency is the most important issue, the choice of the Nd laser material makes a significant difference. The absorption efficiency, storage efficiency, and extraction efficiency for Nd:YAG, Nd:YLF, Nd:GSGG, Nd:BEL, Nd:YVO4, and Nd:glass are calculated. The materials are then compared under the assumption of equal quantum efficiency and damage threshold. Nd:YLF is found to be the best candidate for the application discussed here.

  3. Division of Materials Science (DMS) meeting presentation

    SciTech Connect

    Cline, C.F.; Weber, M.J.

    1982-11-08

    Materials preparation techniques are listed. Materials preparation capabilities are discussed for making BeF/sub 2/ glasses and other materials. Materials characterization techniques are listed. (DLC)

  4. Past, present, and future of endobronchial laser photoresection.

    PubMed

    Khemasuwan, Danai; Mehta, Atul C; Wang, Ko-Pen

    2015-12-01

    Laser photoresection of central airway obstruction is a useful tool for an Interventional Pulmonologist (IP). Endobronchial therapy of the malignant airway obstruction is considered as a palliative measure or a bridge therapy to the definite treatment of cancer. Several ablative therapies such as electrocautery, argon plasma coagulation (APC), cryotherapy and laser photoresection exist in the armamentarium of IP to tackle such presentations. Besides Neodymium-Yttrium, Aluminum, Garnet (Nd:YAG) laser, there are several different types of laser that have been used by the pulmonologist with different coagulative and cutting properties. This chapter focuses on the historical perspective, current status, and potentials of lasers in the management of central airway lesions.

  5. Development of Ceramic Solid-State Laser Host Material

    NASA Technical Reports Server (NTRS)

    Prasad, Narasimha S.; Trivedi, Sudhir; Kutcher, Susan; Wang, Chen-Chia; Kim, Joo-Soo; Hommerich, Uwe; Shukla, Vijay; Sadangi, Rajendra

    2009-01-01

    Polycrystalline ceramic laser materials are gaining importance in the development of novel diode-pumped solid-state lasers. Compared to single-crystals, ceramic laser materials offer advantages in terms of ease of fabrication, shape, size, and control of dopant concentrations. Recently, we have developed Neodymium doped Yttria (Nd:Y2O3) as a solid-state ceramic laser material. A scalable production method was utilized to make spherical non agglomerated and monodisperse metastable ceramic powders of compositions that were used to fabricate polycrystalline ceramic material components. This processing technique allowed for higher doping concentrations without the segregation problems that are normally encountered in single crystalline growth. We have successfully fabricated undoped and Neodymium doped Yttria material up to 2" in diameter, Ytterbium doped Yttria, and erbium doped Yttria. We are also in the process of developing other sesquioxides such as scandium Oxide (Sc2O3) and Lutesium Oxide (Lu2O3) doped with Ytterbium, erbium and thulium dopants. In this paper, we present our initial results on the material, optical, and spectroscopic properties of the doped and undoped sesquioxide materials. Polycrystalline ceramic lasers have enormous potential applications including remote sensing, chem.-bio detection, and space exploration research. It is also potentially much less expensive to produce ceramic laser materials compared to their single crystalline counterparts because of the shorter fabrication time and the potential for mass production in large sizes.

  6. Characterization of laser beam interaction with carbon materials

    NASA Astrophysics Data System (ADS)

    Janićijević, Milovan; Srećković, Milesa; Kaluđerović, Branka; Bojanić, Slobodan; Družijanić, Dragan; Dinulović, Mirko; Kovačević, Aleksander

    2013-05-01

    This paper presents simulation and experimental results for the exposure of some carbon-based materials to alexandrite and Nd3+:YAG (yttrium aluminum garnet) laser radiation. Simulation of the heating effects was carried out using the COMSOL Multiphysics 3.5 package for samples of carbon-based P7295-2 fiber irradiated using an alexandrite laser and carbon-based P4396-2 fiber irradiated using an Nd3+:YAG laser, as well as by applying finite element modeling for P7295-2 samples irradiated using an Nd3+:YAG laser. In the experimental part, P7295-2 samples were exposed to alexandrite laser radiation while samples of carbon-based composite 3D C/C were exposed to Nd3+:YAG laser radiation. Micrographs of the laser induced craters were obtained by light and scanning electron microscopy, and the images analyzed using the ImageJ software. The results obtained enable identification of the laser-material interaction spots, and characterization of the laser induced changes in the materials investigated.

  7. Short-pulse laser interactions with disordered materials and liquids

    SciTech Connect

    Phinney, L.M.; Goldman, C.H.; Longtin, J.P.; Tien, C.L.

    1995-12-31

    High-power, short-pulse lasers in the picosecond and subpicosecond range are utilized in an increasing number of technologies, including materials processing and diagnostics, micro-electronics and devices, and medicine. In these applications, the short-pulse radiation interacts with a wide range of media encompassing disordered materials and liquids. Examples of disordered materials include porous media, polymers, organic tissues, and amorphous forms of silicon, silicon nitride, and silicon dioxide. In order to accurately model, efficiently control, and optimize short-pulse, laser-material interactions, a thorough understanding of the energy transport mechanisms is necessary. Thus, fractals and percolation theory are used to analyze the anomalous diffusion regime in random media. In liquids, the thermal aspects of saturable and multiphoton absorption are examined. Finally, a novel application of short-pulse laser radiation to reduce surface adhesion forces in microstructures through short-pulse laser-induced water desorption is presented.

  8. Femtosecond laser system for micromachining of the materials

    NASA Astrophysics Data System (ADS)

    Barbucha, R.; Kocik, M.; Tański, M.; Garasz, K.; Petrov, T.; Radzewicz, C.

    2015-01-01

    Femtosecond-pulse laser micromachining is based on a laser ablation phenomenon, i.e. total evaporation of material from the target surface during laser irradiation. It is the most precise method of material removal. Moreover it does not require any post processing. Removal of the material occurs only in the laser focus, since the lack of thermal interaction, neither heat affected zone (HAZ) nor debris ocur. Research results have shown that shortening the duration of the laser pulse significantly reduces HAZ, which translates into the high quality of the machined structures. It is the main argument for the use of femtosecond-pulse lasers in the precise micromachining. In this paper, a femtosecond laser system consisting of a solid-state oscillator and the ytterbium-doped pulse fiber amplifier are presented. Average beam power at 343 nm with mode-locking is 4W @25A and pulse length at the oscillator output is 500 fs. Laser micro and nano-machining has found application in different fields. It's primary use is industrial micromachining of metals, ceramics, polymers, glass, biological material for medical use in eye surgery, and photovoltaic cells.

  9. Modeling of Material Removal by Solid State Heat Capacity Lasers

    SciTech Connect

    Boley, C D; Rubenchik, A M

    2002-04-17

    Pulsed lasers offer the capability of rapid material removal. Here we present simulations of steel coupon tests by two solid state heat capacity lasers built at LLNL. Operating at 1.05 pm, these deliver pulse energies of about 80 J at 10 Hz, and about 500 J at 20 Hz. Each is flashlamp-pumped. The first laser was tested at LLNL, while the second laser has been delivered to HELSTF, White Sands Missile Range. Liquid ejection appears to be an important removal mechanism. We have modeled these experiments via a time-dependent code called THALES, which describes heat transport, melting, vaporization, and the hydrodynamics of liquid, vapor, and air. It was previously used, in a less advanced form, to model drilling by copper vapor lasers [1] . It was also used to model vaporization in beam dumps for a high-power laser [2]. The basic model is in 1D, while the liquid hydrodynamics is handled in 2D.

  10. Session: CSP Advanced Systems: Optical Materials (Presentation)

    SciTech Connect

    Kennedy, C.

    2008-04-01

    The Optical Materials project description is to characterize advanced reflector, perform accelerated and outdoor testing of commercial and experimental reflector materials, and provide industry support.

  11. Development of high-power CO2 lasers and laser material processing

    NASA Astrophysics Data System (ADS)

    Nath, Ashish K.; Choudhary, Praveen; Kumar, Manoj; Kaul, R.

    2000-02-01

    Scaling laws to determine the physical dimensions of the active medium and optical resonator parameters for designing convective cooled CO2 lasers have been established. High power CW CO2 lasers upto 5 kW output power and a high repetition rate TEA CO2 laser of 500 Hz and 500 W average power incorporated with a novel scheme for uniform UV pre- ionization have been developed for material processing applications. Technical viability of laser processing of several engineering components, for example laser surface hardening of fine teeth of files, laser welding of martensitic steel shroud and titanium alloy under-strap of turbine, laser cladding of Ni super-alloy with stellite for refurbishing turbine blades were established using these lasers. Laser alloying of pre-placed SiC coating on different types of aluminum alloy, commercially pure titanium and Ti-6Al-4V alloy, and laser curing of thermosetting powder coating have been also studied. Development of these lasers and results of some of the processing studies are briefly presented here.

  12. Laser-beam interactions with materials

    SciTech Connect

    Allmen, M.V.

    1987-01-01

    Lasers are becoming popular tools and research instruments in materials research, metallurgy, semiconductor technology and engineering. This text treats, from a physicist's point of view, the processes that lasers can induce in materials. A broad view of the field and its perspectives is given: physical topics covered range from optics to shock waves, and applications range from semiconductor annealing to fusion-plasma production. Intuitive analytical models are used whenever possible, in order to foster creative thinking and facilitate access to newcomers and nonspecialists.

  13. Past, present, and future of endobronchial laser photoresection.

    PubMed

    Khemasuwan, Danai; Mehta, Atul C; Wang, Ko-Pen

    2015-12-01

    Laser photoresection of central airway obstruction is a useful tool for an Interventional Pulmonologist (IP). Endobronchial therapy of the malignant airway obstruction is considered as a palliative measure or a bridge therapy to the definite treatment of cancer. Several ablative therapies such as electrocautery, argon plasma coagulation (APC), cryotherapy and laser photoresection exist in the armamentarium of IP to tackle such presentations. Besides Neodymium-Yttrium, Aluminum, Garnet (Nd:YAG) laser, there are several different types of laser that have been used by the pulmonologist with different coagulative and cutting properties. This chapter focuses on the historical perspective, current status, and potentials of lasers in the management of central airway lesions. PMID:26807285

  14. Past, present, and future of endobronchial laser photoresection

    PubMed Central

    Khemasuwan, Danai; Wang, Ko-Pen

    2015-01-01

    Laser photoresection of central airway obstruction is a useful tool for an Interventional Pulmonologist (IP). Endobronchial therapy of the malignant airway obstruction is considered as a palliative measure or a bridge therapy to the definite treatment of cancer. Several ablative therapies such as electrocautery, argon plasma coagulation (APC), cryotherapy and laser photoresection exist in the armamentarium of IP to tackle such presentations. Besides Neodymium-Yttrium, Aluminum, Garnet (Nd:YAG) laser, there are several different types of laser that have been used by the pulmonologist with different coagulative and cutting properties. This chapter focuses on the historical perspective, current status, and potentials of lasers in the management of central airway lesions. PMID:26807285

  15. Selective Laser Sintering of Filled Polymer Systems: Bulk Properties and Laser Beam Material Interaction

    NASA Astrophysics Data System (ADS)

    Wudy, Katrin; Lanzl, Lydia; Drummer, Dietmar

    Additive manufacturing techniques, such as selective laser melting of plastics, generate components directly from a CAD data set without using a specific mold. The range of materials commercially available for selective laser sintering merely includes some semi crystalline polymers mainly polyamides, which leads to an absence of realizable component properties. The presented investigations are concerned with the manufacturing and analysis of components made from filled polymer systems by means of selective laser sintering. The test specimens were generated at varied filler concentration, filler types and manufacturing parameter like laser power or scan speed. In addition to the characterization of the mixed powders, resulting melt depth were analyzed in order to investigate the beam material interaction. The basic understanding of the influence of different fillers, filler concentration and manufacturing parameters on resulting component properties will lead to new realizable component properties and thus fields of application of selective laser sintering.

  16. Towards 3-D laser nano patterning in polymer optical materials

    NASA Astrophysics Data System (ADS)

    Scully, Patricia J.; Perrie, Walter

    2015-03-01

    Progress towards 3-D subsurface structuring of polymers using femtosecond lasers is presented. Highly localised refractive index changes can be generated deep in transparent optical polymers without pre doping for photosensitisation or post processing by annealing. Understanding the writing conditions surpasses the limitations of materials, dimensions and chemistry, to facilitate unique structures entirely formed by laser-polymeric interactions to overcome materials, dimensional, refractive index and wavelength constraints.. Numerical aperture, fluence, temporal pulselength, wavelength and incident polarisation are important parameters to be considered, in achieving the desired inscription. Non-linear aspects of multiphoton absorption, plasma generation, filamentation and effects of incident polarisation on the writing conditions will be presented.

  17. Materials processing with a high power diode laser

    SciTech Connect

    Li, L.; Lawrence, J.; Spencer, J.T.

    1996-12-31

    This paper reports on work exploring the feasibility of a range of materials processing applications using a Diomed 60W diode laser delivered through a 600{mu}m diameter optical fibre to a 3 axis CNC workstation. The applications studied include: marking/engraving natural stones (marble and granite), marking ceramic tiles, sealing tile grouts, cutting and marking glass, marking/engraving wood, stripping paint and lacquer, and welding metallic wires. The study shows that even at the present limited power level of diode lasers, many materials processing applications can be accomplished with satisfactory results. Through the study an initial understanding of interaction of high power diode laser (HPDL) beam with various materials has been gained. Also, within the paper basic beam characteristics, and current R&D activities in HPDL technology and materials processing applications are reviewed.

  18. Tetravalent chromium doped laser materials and NIR tunable lasers

    NASA Technical Reports Server (NTRS)

    Alfano, Robert R. (Inventor); Petricevic, Vladimir (Inventor); Bykov, Alexey (Inventor)

    2008-01-01

    A method is described to improve and produce purer Cr.sup.4+-doped laser materials and lasers with reduced co-incorporation of chromium in any other valence states, such as Cr.sup.3+, Cr.sup.2+, Cr.sup.5+, and Cr.sup.6+. The method includes: 1) certain crystals of olivine structure with large cation (Ca) in octahedral sites such as Cr.sup.4+:Ca.sub.2GeO.sub.4, Cr.sup.4+:Ca.sub.2SiO.sub.4, Cr.sup.4+:Ca.sub.2Ge.sub.xSi.sub.1-xO.sub.4 (where 0laser materials are characterized by a relatively high concentration of Cr.sup.4+-lasing ion in crystalline host that makes these materials suitable for compact high power (thin disk/wedge) NIR laser applications.

  19. Laser remote cutting of metallic materials: opportunities and limitations

    NASA Astrophysics Data System (ADS)

    Wetzig, Andreas; Baumann, Robert; Herwig, Patrick; Siebert, René; Beyer, Eckhard

    2015-07-01

    The fundamentals of laser remote cutting will be introduced as well as a comparison to the conventional laser fusion cutting process. The opportunities and limitations of this alternative laser cutting technology will be discussed in detail by means of recent application examples. Here to name cutting of typical punching and bending parts, battery foils, metals foams and electrical steel sheets. Questions that are concerning the cutting thickness, the cutting quality, the cycle time, and the impact on the material will be answered. Finally, conclusions and an outlook on future developments will be presented.

  20. Activation of cells using femtosecond laser beam (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Batabyal, Subrata; Satpathy, Sarmishtha; Kim, Young-tae; Mohanty, Samarendra K.

    2016-03-01

    Study of communication in cellular systems requires precise activation of targeted cell(s) in the network. In contrast to chemical, electrical, thermal, mechanical stimulation, optical stimulation is non-invasive and is better suited for stimulation of targeted cells. As compared to visible lasers, the near infrared (NIR) microsecond/nanosecond pulsed laser beams are being used as preferred stimulation tool as they provide higher penetration depth in tissues. Femotosecond (FS) laser beams in NIR are also being used for direct and indirect (i.e. via two-photon optogenetics) stimulation of cells. Here, we present a comparative evaluation of efficacy of NIR FS laser beam for direct (no optogenetic sensitization) and 2ph optogenetic stimulation of cells. Further, for the first time, we demonstrate the use of blue (~450 nm, obtained by second harmonic generation) FS laser beam for stimulation of cells with and without Channelrhodopisn-2 (ChR2) expression. Comparative analysis of photocurrent generated by blue FS laser beam and continuous wave blue light for optogenetics stimulation of ChR2 transfected HEK cells will be presented. The use of ultrafast laser micro-beam for focal, non-contact, and repeated stimulation of single cells in a cellular circuitry allowed us to study the communication between different cell types.

  1. Review of selective laser melting: Materials and applications

    NASA Astrophysics Data System (ADS)

    Yap, C. Y.; Chua, C. K.; Dong, Z. L.; Liu, Z. H.; Zhang, D. Q.; Loh, L. E.; Sing, S. L.

    2015-12-01

    Selective Laser Melting (SLM) is a particular rapid prototyping, 3D printing, or Additive Manufacturing (AM) technique designed to use high power-density laser to melt and fuse metallic powders. A component is built by selectively melting and fusing powders within and between layers. The SLM technique is also commonly known as direct selective laser sintering, LaserCusing, and direct metal laser sintering, and this technique has been proven to produce near net-shape parts up to 99.9% relative density. This enables the process to build near full density functional parts and has viable economic benefits. Recent developments of fibre optics and high-power laser have also enabled SLM to process different metallic materials, such as copper, aluminium, and tungsten. Similarly, this has also opened up research opportunities in SLM of ceramic and composite materials. The review presents the SLM process and some of the common physical phenomena associated with this AM technology. It then focuses on the following areas: (a) applications of SLM materials and (b) mechanical properties of SLM parts achieved in research publications. The review is not meant to put a ceiling on the capabilities of the SLM process but to enable readers to have an overview on the material properties achieved by the SLM process so far. Trends in research of SLM are also elaborated in the last section.

  2. Review of selective laser melting: Materials and applications

    SciTech Connect

    Yap, C. Y.; Chua, C. K. Liu, Z. H. Zhang, D. Q. Loh, L. E. Sing, S. L.; Dong, Z. L.

    2015-12-15

    Selective Laser Melting (SLM) is a particular rapid prototyping, 3D printing, or Additive Manufacturing (AM) technique designed to use high power-density laser to melt and fuse metallic powders. A component is built by selectively melting and fusing powders within and between layers. The SLM technique is also commonly known as direct selective laser sintering, LaserCusing, and direct metal laser sintering, and this technique has been proven to produce near net-shape parts up to 99.9% relative density. This enables the process to build near full density functional parts and has viable economic benefits. Recent developments of fibre optics and high-power laser have also enabled SLM to process different metallic materials, such as copper, aluminium, and tungsten. Similarly, this has also opened up research opportunities in SLM of ceramic and composite materials. The review presents the SLM process and some of the common physical phenomena associated with this AM technology. It then focuses on the following areas: (a) applications of SLM materials and (b) mechanical properties of SLM parts achieved in research publications. The review is not meant to put a ceiling on the capabilities of the SLM process but to enable readers to have an overview on the material properties achieved by the SLM process so far. Trends in research of SLM are also elaborated in the last section.

  3. Photovoltaic materials: Present efficiencies and future challenges.

    PubMed

    Polman, Albert; Knight, Mark; Garnett, Erik C; Ehrler, Bruno; Sinke, Wim C

    2016-04-15

    Recent developments in photovoltaic materials have led to continual improvements in their efficiency. We review the electrical characteristics of 16 widely studied geometries of photovoltaic materials with efficiencies of 10 to 29%. Comparison of these characteristics to the fundamental limits based on the Shockley-Queisser detailed-balance model provides a basis for identifying the key limiting factors, related to efficient light management and charge carrier collection, for these materials. Prospects for practical application and large-area fabrication are discussed for each material.

  4. Femtosecond laser ablation properties of transparent materials: impact of the laser process parameters on the machining throughput

    NASA Astrophysics Data System (ADS)

    Matylitsky, V. V.; Hendricks, F.; Aus der Au, J.

    2013-03-01

    High average power, high repetition rate femtosecond lasers with μJ pulse energies are increasingly used for bio-medical and material processing applications. With the introduction of femtosecond laser systems such as the SpiritTM platform developed by High Q Lasers and Spectra-Physics, micro-processing of solid targets with femtosecond laser pulses have obtained new perspectives for industrial applications [1]. The unique advantage of material processing with subpicosecond lasers is efficient, fast and localized energy deposition, which leads to high ablation efficiency and accuracy in nearly all kinds of solid materials. The study on the impact of the laser processing parameters on the removal rate for transparent substrate using femtosecond laser pulses will be presented. In particular, examples of micro-processing of poly-L-lactic acid (PLLA) - bio-degradable polyester and XensationTM glass (Schott) machined with SpiritTM ultrafast laser will be shown.

  5. Modeling of laser interactions with composite materials

    DOE PAGES

    Rubenchik, Alexander M.; Boley, Charles D.

    2013-05-07

    In this study, we develop models of laser interactions with composite materials consisting of fibers embedded within a matrix. A ray-trace model is shown to determine the absorptivity, absorption depth, and optical power enhancement within the material, as well as the angular distribution of the reflected light. We also develop a macroscopic model, which provides physical insight and overall results. We show that the parameters in this model can be determined from the ray trace model.

  6. Lunar Science from Laser Ranging - Present and Future

    NASA Technical Reports Server (NTRS)

    Ratcliff, J. Todd; Williams, James G.; Turyshev, S. G.

    2008-01-01

    The interior properties of the Moon influence lunar tides and rotation. Three-axis rotation (physical librations) and tides are sensed by tracking lunar landers. The Lunar Laser Ranging (LLR) experiment has acquired 38 yr of increasingly accurate ranges from observatories on the Earth to four corner cube retroreflector arrays on the Moon. Lunar Laser Ranging is reviewed in [1]. Recent lunar science results are in [4,5]. In this abstract present LLR capabilities are described followed by future possibilities.

  7. Power plant material characterization by lasers

    SciTech Connect

    Not Available

    1993-02-01

    The EPRI Nuclear Division undertook examination of the feasibility of utilizing lasers to perform in situ operations within power plants in 1983. The Nd- Yag laser was of particular interest because flexible fiber optics cabling could be utilized for beam transport; the end effectors could be made small enough to access power plant components remotely. Beam management for welding and metal conditioning in confined spaces; the first issue examined, lead to the application for steam generator repairs that is now in common usage. This report examines the laser beam as a source of information about the material property condition; an application made feasible by advances in fiber and laser technology that were achieved beginning in 1989. This work, examines the prospects for determination of material condition properties within power plants because the laser beam can be utilized for sampling and as a source of optical, thermal, ultrasonic, spectrographic and mensuration data that may be obtained nondestructively. Both application evaluations and feasibility testing is described.

  8. Ultrashort-pulse laser generated nanoparticles of energetic materials

    DOEpatents

    Welle, Eric J.; Tappan, Alexander S.; Palmer, Jeremy A.

    2010-08-03

    A process for generating nanoscale particles of energetic materials, such as explosive materials, using ultrashort-pulse laser irradiation. The use of ultrashort laser pulses in embodiments of this invention enables one to generate particles by laser ablation that retain the chemical identity of the starting material while avoiding ignition, deflagration, and detonation of the explosive material.

  9. Laser Induced Damage in Optical Materials: 6th ASTM Symposium.

    PubMed

    Glass, A J; Guenther, A H

    1975-03-01

    The Sixth ASTM-ONR-NBS Symposium on Laser Induced Damage in Optical Materials was held at the National Bureau of Standards in Boulder, Colorado on 22-23 May 1974. Over 150 attendees at the Symposium heard thirty-one papers on topics relating to laser induced damage in crystalline and nonlinear optical materials, at dielectric surfaces, and in thin film coatings as well as discussions of damage problems in the ir region due both to cw and pulsed irradiation. In addition, several reports on the theoretical analysis of laser-materials interaction relative to the damage progress were given, along with tabulations of fundamental materials properties of importance in evaluation of optical material response to high-power laser radiation. Attention was given to high-power laser system design considerations that relate to improved system performance and reliability when various damage mechanisms are operable in such systems. A workshop on the machining of optics was held, and nine papers on various facets of the topic were presented dealing with machining procedures, surface characterization of machined elements, coating of machined components, and the polishing and damage resistance of polished, coated, and bare metal reflectors. PMID:20134954

  10. Micromachining of microelectronic materials with deep-UV lasers

    NASA Astrophysics Data System (ADS)

    Toenshoff, Hans K.; von Alvensleben, Ferdinand; Kappel, Heiner; Heekenjann, Peter B.

    1997-05-01

    Micromachining requires very precise tools with high resolution. Lasers emitting electromagnetic radiation in the ultraviolet (UV) region offer focussed spot sizes less than one micrometer. Wavelengths in the range of lambda equals 200 to 280 nm are called deep ultraviolet (DUV) and ensure minimal resolution for actual and future application in microelectronics. Conventional DUV-lasers are the well developed excimer-lasers and frequency converted systems such as Nd:YLF, Nd:YAG and Ar+-lasers. DUV-lasers can be used for submicron single pulse machining up to processing of complex surfaces for the great variety of microelectronic components. The process efficiency is determined not only by the choice of the laser source itself, but also by the system technology such as optical elements for beam shaping and guidance or workpiece handling. Besides the system technology, the choice of an appropriate laser and handling system ensures an efficient processing and repair of microelectronic components. The presented examples cover the direct writing of conductive layers on ceramic material in combination with electroplating, which offers ways of rapid prototyping printed circuit boards (PCB). Furthermore, the repair of expensive electronic products is of growing interest. Examples are the repair of photolithography masks. An overview of further opportunities using DUV-lasers is given by 3D structuring of glass and ceramics.

  11. Tubular filamentation for laser material processing

    PubMed Central

    Xie, Chen; Jukna, Vytautas; Milián, Carles; Giust, Remo; Ouadghiri-Idrissi, Ismail; Itina, Tatiana; Dudley, John M.; Couairon, Arnaud; Courvoisier, Francois

    2015-01-01

    An open challenge in the important field of femtosecond laser material processing is the controlled internal structuring of dielectric materials. Although the availability of high energy high repetition rate femtosecond lasers has led to many advances in this field, writing structures within transparent dielectrics at intensities exceeding 1013 W/cm2 has remained difficult as it is associated with significant nonlinear spatial distortion. This letter reports the existence of a new propagation regime for femtosecond pulses at high power that overcomes this challenge, associated with the generation of a hollow uniform and intense light tube that remains propagation invariant even at intensities associated with dense plasma formation. This regime is seeded from higher order nondiffracting Bessel beams, which carry an optical vortex charge. Numerical simulations are quantitatively confirmed by experiments where a novel experimental approach allows direct imaging of the 3D fluence distribution within transparent solids. We also analyze the transitions to other propagation regimes in near and far fields. We demonstrate how the generation of plasma in this tubular geometry can lead to applications in ultrafast laser material processing in terms of single shot index writing, and discuss how it opens important perspectives for material compression and filamentation guiding in atmosphere. PMID:25753215

  12. Tubular filamentation for laser material processing

    NASA Astrophysics Data System (ADS)

    Xie, Chen; Jukna, Vytautas; Milián, Carles; Giust, Remo; Ouadghiri-Idrissi, Ismail; Itina, Tatiana; Dudley, John M.; Couairon, Arnaud; Courvoisier, Francois

    2015-03-01

    An open challenge in the important field of femtosecond laser material processing is the controlled internal structuring of dielectric materials. Although the availability of high energy high repetition rate femtosecond lasers has led to many advances in this field, writing structures within transparent dielectrics at intensities exceeding 1013 W/cm2 has remained difficult as it is associated with significant nonlinear spatial distortion. This letter reports the existence of a new propagation regime for femtosecond pulses at high power that overcomes this challenge, associated with the generation of a hollow uniform and intense light tube that remains propagation invariant even at intensities associated with dense plasma formation. This regime is seeded from higher order nondiffracting Bessel beams, which carry an optical vortex charge. Numerical simulations are quantitatively confirmed by experiments where a novel experimental approach allows direct imaging of the 3D fluence distribution within transparent solids. We also analyze the transitions to other propagation regimes in near and far fields. We demonstrate how the generation of plasma in this tubular geometry can lead to applications in ultrafast laser material processing in terms of single shot index writing, and discuss how it opens important perspectives for material compression and filamentation guiding in atmosphere.

  13. Tubular filamentation for laser material processing.

    PubMed

    Xie, Chen; Jukna, Vytautas; Milián, Carles; Giust, Remo; Ouadghiri-Idrissi, Ismail; Itina, Tatiana; Dudley, John M; Couairon, Arnaud; Courvoisier, Francois

    2015-01-01

    An open challenge in the important field of femtosecond laser material processing is the controlled internal structuring of dielectric materials. Although the availability of high energy high repetition rate femtosecond lasers has led to many advances in this field, writing structures within transparent dielectrics at intensities exceeding 10(13) W/cm(2) has remained difficult as it is associated with significant nonlinear spatial distortion. This letter reports the existence of a new propagation regime for femtosecond pulses at high power that overcomes this challenge, associated with the generation of a hollow uniform and intense light tube that remains propagation invariant even at intensities associated with dense plasma formation. This regime is seeded from higher order nondiffracting Bessel beams, which carry an optical vortex charge. Numerical simulations are quantitatively confirmed by experiments where a novel experimental approach allows direct imaging of the 3D fluence distribution within transparent solids. We also analyze the transitions to other propagation regimes in near and far fields. We demonstrate how the generation of plasma in this tubular geometry can lead to applications in ultrafast laser material processing in terms of single shot index writing, and discuss how it opens important perspectives for material compression and filamentation guiding in atmosphere. PMID:25753215

  14. Laser-material interactions: A study of laser energy coupling with solids

    SciTech Connect

    Shannon, M A

    1993-11-01

    This study of laser-light interactions with solid materials ranges from low-temperature heating to explosive, plasma-forming reactions. Contained are four works concerning laser-energy coupling: laser (i) heating and (ii) melting monitored using a mirage effect technique, (iii) the mechanical stress-power generated during high-powered laser ablation, and (iv) plasma-shielding. First, a photothermal deflection (PTD) technique is presented for monitoring heat transfer during modulated laser heating of opaque solids that have not undergone phase-change. Of main interest is the physical significance of the shape, magnitude, and phase for the temporal profile of the deflection signal. Considered are the effects that thermophysical properties, boundary conditions, and geometry of the target and optical probe-beam have on the deflection response. PTD is shown to monitor spatial and temporal changes in heat flux leaving the surface due to changes in laser energy coupling. The PTD technique is then extended to detect phase-change at the surface of a solid target. Experimental data shows the onset of melt for indium and tin targets. The conditions for which melt can be detected by PTD is analyzed in terms of geometry, incident power and pulse length, and thermophysical properties of the target and surroundings. Next, monitoring high-powered laser ablation of materials with stress-power is introduced. The motivation for considering stress-power is given, followed by a theoretical discussion of stress-power and how it is determined experimentally. Experiments are presented for the ablation of aluminum targets as a function of energy and intensity. The stress-power response is analyzed for its physical significance. Lastly, the influence of plasma-shielding during high-powered pulsed laser-material interactions is considered. Crater size, emission, and stress-power are measured to determine the role that the gas medium and laser pulse length have on plasma shielding.

  15. Ultrafast laser spectroscopy in complex solid state materials

    SciTech Connect

    Li, Tianqi

    2014-12-01

    This thesis summarizes my work on applying the ultrafast laser spectroscopy to the complex solid state materials. It shows that the ultrafast laser pulse can coherently control the material properties in the femtosecond time scale. And the ultrafast laser spectroscopy can be employed as a dynamical method for revealing the fundamental physical problems in the complex material systems.

  16. Long-Lifetime Laser Materials For Effective Diode Pumping

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.

    1991-01-01

    Long quantum lifetimes reduce number of diodes required to pump. Pumping by laser diodes demonstrated with such common Nd laser materials as neodymium:yttrium aluminum garnet (Nd:YAG) and Nd:YLiF4, but such materials as Nd:LaF3, Nd:NaF.9YF3, and possibly Nd:YF3 more useful because of long lifetimes of their upper laser energy levels. Cost effectiveness primary advantage of solid-state laser materials having longer upper-laser-level lifetimes. Because cost of diodes outweighs cost of laser material by perhaps two orders of magnitude, cost reduced significantly.

  17. Creating Extreme Material Properties with High-Energy Laser Systems

    NASA Astrophysics Data System (ADS)

    Meyerhofer, David

    2005-07-01

    Laboratory for Laser Energetics, University of Rochester, 250 E. River Rd, Rochester, NY 14623 High-energy laser systems create extreme states of matter by coupling their energy into a target via ablation of the outer layers. In planar experiments on the OMEGA laser system, single-shock pressures can exceed 10 Mbar. In spherical geometry, the compressed target pressures can be significantly higher than 1 Gbar. These pressures will be increased by one or two orders of magnitude on the 1.8-MJUV National Ignition Facility, under construction at LLNL. The inherent flexibility of multibeam laser systems allows many techniques to be applied to studying the properties of materials under extreme conditions. Recent experiments have used Extended X-ray Absorption Fine Structure to observe shock-induced phase transformations in Fe on the ns time scale. Techniques are being used and/or developed to measure the equation of state of compressed materials, including solids, foams, and liquid D2, both on and off the Hugoniot. The coupling of high-energy petawatt (HEPW) lasers to high-energy laser systems will greatly extend the accessible range of material conditions. HEPW lasers produce extremely intense beams of electrons and protons that can be coupled with high-energy compression to access a large region of temperature and density space, for example, by heating a compressed target. These beams, along with the extremely bright x-ray emission, provide new diagnostic opportunities. This presentation will highlight some of the recent advances and future opportunities in creating and measuring extreme materials properties. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-92SF19460, the University of Rochester, and the NY State Energy Research and Development Authority. The support of DOE does not constitute an endorsement by DOE of the views expressed in this article.

  18. The advances and characteristics of high-power diode laser materials processing

    NASA Astrophysics Data System (ADS)

    Li, Lin

    2000-10-01

    This paper presents a review of the direct applications of high-power diode lasers for materials processing including soldering, surface modification (hardening, cladding, glazing and wetting modifications), welding, scribing, sheet metal bending, marking, engraving, paint stripping, powder sintering, synthesis, brazing and machining. The specific advantages and disadvantages of diode laser materials processing are compared with CO 2, Nd:YAG and excimer lasers. An effort is made to identify the fundamental differences in their beam/material interaction characteristics and materials behaviour. Also an appraisal of the future prospects of the high-power diode lasers for materials processing is given.

  19. Laser nano-surgery for neuronal manipulation (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Sarker, Hori Pada; Chudal, Lalit; Mahapatra, Vasu; Kim, Young-tae; Mohanty, Samarendra K.

    2016-03-01

    Optical manipulation has enabled study of bio-chemical and bio-mechanical properties of the cells. Laser nanosurgery by ultrafast laser beam with appropriate laser parameters provides spatially-targeted manipulation of neurons in a minimal invasiveness manner with high efficiency. We utilized femto-second laser nano-surgery for both axotomy and sub-axotomy of rat cortical neurons. Degeneration and regeneration after axotomy was studied with and without external growth-factor(s) and biochemical(s). Further, axonal injury was studied as a function of pulse energy, exposure and site of injury. The ability to study the response of neurons to localized injury opens up opportunities for screening potential molecules for repair and regeneration after nerve injury. Sub-axotomy enabled transient opening of axonal membrane for optical delivery of impermeable molecules to the axoplasm. Fast resealing of the axonal membrane after sub-axotomy without significant long-term damage to axon (monitored by its growth) was observed. We will present these experimental results along with theoretical simulation of injury due to laser nano-surgery and delivery via the transient pore. Targeted delivery of proteins such as antibodies, genes encoding reporter proteins, ion-channels and voltage indicators will allow visualization, activation and detection of the neuronal structure and function.

  20. Kilowatt average-power laser for subpicosecond materials processing

    NASA Astrophysics Data System (ADS)

    Benson, Stephen V.; Neil, George R.; Bohn, Courtlandt L.; Biallas, George; Douglas, David; Dylla, H. Frederick; Fugitt, Jock; Jordan, Kevin; Krafft, Geoffrey; Merminga, Lia; Preble, Joe; Shinn, Michelle D.; Siggins, Tim; Walker, Richard; Yunn, Byung

    2000-04-01

    The performance of laser pulses in the sub-picosecond range for materials processing is substantially enhanced over similar fluences delivered in longer pulses. Recent advances in the development of solid state lasers have progressed significantly toward the higher average powers potentially useful for many applications. Nonetheless, prospects remain distant for multi-kilowatt sub-picosecond solid state systems such as would be required for industrial scale surface processing of metals and polymers. We present operation results from the world's first kilowatt scale ultra-fast materials processing laser. A Free Electron Laser (FEL) called the IR Demo is operational as a User Facility at Thomas Jefferson National Accelerator Facility in Newport News, Virginia, USA. In its initial operation at high average power it is capable of wavelengths in the 2 to 6 micron range and can produce approximately 0.7 ps pulses in a continuous train at approximately 75 MHz. This pulse length has been shown to be nearly optimal for deposition of energy in materials at the surface. Upgrades in the near future will extend operation beyond 10 kW CW average power in the near IR and kilowatt levels of power at wavelengths from 0.3 to 60 microns. This paper will cover the design and performance of this groundbreaking laser and operational aspects of the User Facility.

  1. Optical materials for space based laser systems

    NASA Technical Reports Server (NTRS)

    Buoncristiani, A. M.; Armagan, G.; Byvik, C. E.; Albin, S.

    1989-01-01

    The design features and performance characteristics of a sensitized holmium laser applicable to differential lidar and Doppler windshear measurements are presented, giving attention to the optimal choice of sensitizing/activating dopant ions. This development of a 2-micron region eye-safe laser, where holmium is sensitized by either hulium or erbium, has called for interionic energy transfer processes whose rate will not result in gain-switched pulses that are excessively long for atmospheric lidar and Doppler windshear detection. The application of diamond films for optical component hardening is noted.

  2. Nuclear Material Detection by One-Short-Pulse-Laser-Driven Neutron Source

    SciTech Connect

    Favalli, Andrea; Aymond, F.; Bridgewater, Jon S.; Croft, Stephen; Deppert, O.; Devlin, Matthew James; Falk, Katerina; Fernandez, Juan Carlos; Gautier, Donald Cort; Gonzales, Manuel A.; Goodsell, Alison Victoria; Guler, Nevzat; Hamilton, Christopher Eric; Hegelich, Bjorn Manuel; Henzlova, Daniela; Ianakiev, Kiril Dimitrov; Iliev, Metodi; Johnson, Randall Philip; Jung, Daniel; Kleinschmidt, Annika; Koehler, Katrina Elizabeth; Pomerantz, Ishay; Roth, Markus; Santi, Peter Angelo; Shimada, Tsutomu; Swinhoe, Martyn Thomas; Taddeucci, Terry Nicholas; Wurden, Glen Anthony; Palaniyappan, Sasikumar; McCary, E.

    2015-01-28

    Covered in the PowerPoint presentation are the following areas: Motivation and requirements for active interrogation of nuclear material; laser-driven neutron source; neutron diagnostics; active interrogation of nuclear material; and, conclusions, remarks, and future works.

  3. Laser-induced shock waves effects in materials

    SciTech Connect

    Dingus, R.S.; Shafer, B.P.

    1990-01-01

    A review of the effects of pressure pulses on materials is presented with an orientation toward laser-induced shock wave effects in biological tissue. The behavior is first discussed for small amplitudes, namely sound waves, since many important features in this region are also applicable at large amplitudes. The generation of pressure pulses by lasers is discussed along with amplitudes. The origin and characteristic properties of shock waves are discussed along with the different types of effects they can produce. The hydrodynamic code techniques required for shock wave calculations are discussed along with the necessary empirical data base and methods for generating that data base. 7 refs., 15 figs.

  4. Damage thresholds in laser irradiated optical materials

    SciTech Connect

    Guignard, F.; Autric, M.; Baudinaud, V.

    1997-12-01

    An experimental study on the damage induced by laser irradiation on different materials, borosilicate glass, fused silicate, moulded and stretched polymethylmethacrylate (PMMA), has been performed. The irradiation source is a 1KJ pulsed cold cathode electron gun preionized TEA CO{sub 2} laser. Damage mechanisms are controlled by the in-depth absorption of the 10,6 {mu}m radiation according to the Beer-Lambert law. The heating of the interaction area gives rise to thermal or thermo-mechanical damages. PMMA is damaged following a boiling process. Stretched PMMA is fractured first, releasing stresses, then boiled like moulded PMMA at higher energy. BK7 crazed after the irradiation due to thermomechanical stresses, silicate melt and vaporized. Optical damages have been characterized by measuring the contrast transfer function through the irradiated samples.

  5. Laser Ablation of Materials for Propulsion of Spacecraft

    NASA Technical Reports Server (NTRS)

    Edwards, David L.; Carruth, Ralph; Campbell, Jonathan; Gray, Perry

    2004-01-01

    A report describes experiments performed as part of a continuing investigation of the feasibility of laser ablation of materials as a means of propulsion for small spacecraft. In each experiment, a specimen of ablative material was mounted on a torsion pendulum and irradiated with a laser pulse having an energy of 5 J. The amplitude of the resulting rotation of the torsion pendulum was taken to be an indication of the momentum transferred from the laser beam. Of the ablative materials tested, aluminum foils yielded the smallest rotation amplitudes of the order of 10 degrees. Black coating materials yielded rotation amplitudes of the order of 90 degrees. Samples of silver coated with a fluorinated ethylene propylene (FEP) copolymer yielded the largest rotation amplitudes 6 to 8 full revolutions. The report presents a theory involving heating of a confined plasma followed by escape of the plasma to explain the superior momentum transfer performance of the FEP specimens. It briefly discusses some concepts for optimizing designs of spacecraft engines to maximize the thrust obtainable by exploiting the physical mechanisms of the theory. Also discussed is the use of laser-ablation engines with other types of spacecraft engines.

  6. HO:LULF and HO:LULF Laser Materials

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P. (Inventor); Morrison, Clyde A. (Inventor); Filer, Elizabeth D. (Inventor); Jani, Mahendra G. (Inventor); Murray, Keith E. (Inventor); Lockard, George E. (Inventor)

    1998-01-01

    A laser host material LULF (LuLiF4) is doped with holmium (Ho) and thulium (Tm) to produce a new laser material that is capable of laser light production in the vicinity of 2 microns. The material provides an advantage in efficiency over conventional Ho lasers because the LULF host material allows for decreased threshold and upconversion over such hosts as YAG and YLF. The addition of Tm allows for pumping by commonly available GaAlAs laser diodes. For use with flashlamp pumping, erbium (Er) may be added as an additional dopant. For further upconversion reduction, the Tm can be eliminated and the Ho can be directly pumped.

  7. Heating of optical materials by pulsed CO2 laser radiation

    NASA Astrophysics Data System (ADS)

    Dmitriev, E. I.; Sakyan, A. S.; Starchenko, Aleksey N.; Goryachkin, Dmitri A.

    1998-12-01

    The results are presented on experimental investigations of action onto an optical glass BK-7 and some other materials of a CO2 laser radiation with the pulse duration of 20 - 70 microsecond(s) and the energy density of 0.1 - 3 J/cm2. The dynamics of a thermal response, temperature of heating and emissivity of irradiated glass samples are under consideration. The results obtained can be used in imaging techniques for objects selection.

  8. Laser induced damage in optical materials: tenth ASTM symposium.

    PubMed

    Glass, A J; Guenther, A H

    1979-07-01

    The tenth annual Symposium on Optical Materials for High Power Lasers (Boulder Damage Symposium) was held at the National Bureau of Standards in Boulder, Colorado, 12-14 September 1978. The symposium was held under the auspices of ASTM Committee F-1, Subcommittee on Laser Standards, with the joint sponsorship of NBS, the Defense Advanced Research Project Agency, the Department of Energy, and the Office of Naval Research. About 175 scientists attended, including representatives of the United Kingdom, France, Canada, Japan, West Germany, and the Soviet Union. The symposium was divided into sessions concerning the measurement of absorption characteristics, bulk material properties, mirrors and surfaces, thin film damage, coating materials and design, and breakdown phenomena. As in previous years, the emphasis of the papers presented was directed toward new frontiers and new developments. Particular emphasis was given to materials for use from 10.6 microm to the UV region. Highlights included surface characterization, thin film-substrate boundaries, and advances in fundamental laser-matter threshold interactions and mechanisms. The scaling of damage thresholds with pulse duration, focal area, and wavelength was also discussed. In commemoration of the tenth symposium in this series, a number of comprehensive review papers were presented to assess the state of the art in various facets of laser induced damage in optical materials. Alexander J. Glass of Lawrence Livermore Laboratory and Arthur H. Guenther of the Air Force Weapons Laboratory were co-chairpersons. The eleventh annual symposium is scheduled for 30-31 October 1979 at the National Bureau of Standards, Boulder, Colorado.

  9. Materials Development and Evaluation of Selective Laser Sintering Manufacturing Applications

    SciTech Connect

    Smith, Peter F.; Mitchell, Russell R.

    1997-01-15

    This report summarizes the FY96 accomplishments for CRADA No. LA95C10254, "Materials Development and Evaluation of Laser Sintering Manufacturing Applications". To research the potential for processing additional materials using DTM Corporations Selective Laser Sintering rapid prototyping technology and evaluate the capability for rapid manufacturing applications, the following materials were processed experimentally using the Sinterstation 2000 platform; Linear Low Density Polyethylene thermoplastic; Polypropylene thermoplastic; Polysulfone thermoplastic; Polymethylpentene (TPX) thermoplastic; Carbon microsphere filled nylon 11; "APO-BMI" Apocure bismaleimide thermoset polyimide glass m.icrosphere filled and carbon microsphere filled formulations; and 900-24 physical properties mock for plastic bonded TATB high explosive These materials have been successfully processed to a "proof of concept" level or better (with the exception of No. 7). While none of these materials have been introduced as a standard product as of this date, the potential to do so is viable. Present status of materials processing efforts is presented in Section A 2.0. Some recent efforts in manufacturing applications is discussed in Section A 4.0.

  10. Short-pulse laser materials processing

    SciTech Connect

    Stuart, B.C.; Perry, M.D.; Myers, B.R.; Banks, P.S.; Honea, E.C.

    1997-06-18

    While there is much that we have learned about materials processing in the ultrashort-pulse regime, there is an enormous amount that we don`t know. How short does the pulse have to be to achieve a particular cut (depth, material, quality)? How deep can you cut? What is the surface roughness? These questions are clearly dependent upon the properties of the material of interest along with the short-pulse interaction physics. From a technology standpoint, we are asked: Can you build a 100 W average power system ? A 1000 W average power system? This proposal seeks to address these questions with a combined experimental and theoretical program of study. Specifically, To develop an empirical database for both metals and dielectrics which can be used to determine the pulse duration and wavelength necessary to achieve a specific machining requirement. To investigate Yb:YAG as a potential laser material for high average power short-pulse systems both directly and in combination with titanium doped sapphire. To develop a conceptual design for a lOOW and eventually 5OOW average power short-pulse system.

  11. Modification of transparent materials with ultrashort laser pulses: What is energetically and mechanically meaningful?

    SciTech Connect

    Bulgakova, Nadezhda M.; Zhukov, Vladimir P.; Sonina, Svetlana V.; Meshcheryakov, Yuri P.

    2015-12-21

    A comprehensive analysis of laser-induced modification of bulk glass by single ultrashort laser pulses is presented which is based on combination of optical Maxwell-based modeling with thermoelastoplastic simulations of post-irradiation behavior of matter. A controversial question on free electron density generated inside bulk glass by ultrashort laser pulses in modification regimes is addressed on energy balance grounds. Spatiotemporal dynamics of laser beam propagation in fused silica have been elucidated for the regimes used for direct laser writing in bulk glass. 3D thermoelastoplastic modeling of material relocation dynamics under laser-induced stresses has been performed up to the microsecond timescale when all motions in the material decay. The final modification structure is found to be imprinted into material matrix already at sub-nanosecond timescale. Modeling results agree well with available experimental data on laser light transmission through the sample and the final modification structure.

  12. Modification of transparent materials with ultrashort laser pulses: What is energetically and mechanically meaningful?

    NASA Astrophysics Data System (ADS)

    Bulgakova, Nadezhda M.; Zhukov, Vladimir P.; Sonina, Svetlana V.; Meshcheryakov, Yuri P.

    2015-12-01

    A comprehensive analysis of laser-induced modification of bulk glass by single ultrashort laser pulses is presented which is based on combination of optical Maxwell-based modeling with thermoelastoplastic simulations of post-irradiation behavior of matter. A controversial question on free electron density generated inside bulk glass by ultrashort laser pulses in modification regimes is addressed on energy balance grounds. Spatiotemporal dynamics of laser beam propagation in fused silica have been elucidated for the regimes used for direct laser writing in bulk glass. 3D thermoelastoplastic modeling of material relocation dynamics under laser-induced stresses has been performed up to the microsecond timescale when all motions in the material decay. The final modification structure is found to be imprinted into material matrix already at sub-nanosecond timescale. Modeling results agree well with available experimental data on laser light transmission through the sample and the final modification structure.

  13. Blackbody absorption efficiencies for six lamp pumped Nd laser materials

    NASA Technical Reports Server (NTRS)

    Cross, Patricia L.; Barnes, Norman P.; Skolaut, Milton W., Jr.; Storm, Mark E.

    1990-01-01

    Utilizing high resolution spectra, the absorption efficiencies for six Nd laser materials were calculated as functions of the effective blackbody temperature of the lamp and laser crystal size. The six materials were Nd:YAG, Nd:YLF, Nd:Q-98 Glass, Nd:YVO4, Nd:BEL, and Nd:Cr:GSGG. Under the guidelines of this study, Nd:Cr:GSGG's absorption efficiency is twice the absorption efficiency of any of the other laser materials.

  14. Ultrafast laser diagnostics to investigate initiation fundamentals in energetic materials.

    SciTech Connect

    Farrow, Darcie; Jilek, Brook Anton; Kohl, Ian Thomas; Kearney, Sean Patrick

    2013-08-01

    We present the results of a two year early career LDRD project, which has focused on the development of ultrafast diagnostics to measure temperature, pressure and chemical change during the shock initiation of energetic materials. We compare two single-shot versions of femtosecond rotational CARS to measure nitrogen temperature: chirped-probe-pulse and ps/fs hybrid CARS thermometry. The applicability of measurements to the combustion of energetic materials will be discussed. We have also demonstrated laser shock and particle velocity measurements in thin film explosives using stretched femtosecond laser pulses. We will discuss preliminary results from Al and PETN thin films. Agreement between our results and previous work will be discussed.

  15. Laser micro welding of copper and aluminium using filler materials

    NASA Astrophysics Data System (ADS)

    Esser, Gerd; Mys, Ihor; Schmidt, Michael H.

    2004-10-01

    The most evident trend in electronics production is towards miniaturization. Regarding the materials involved, another trend can be observed: intelligent combinations of different materials. One example is the combination of copper and aluminium. Copper is the material of choice for electronic packaging applications due to its superior electrical and thermal conductivity. On the other hand, aluminium offers technical and economical advantages with respect to cost and component weight -- still providing thermal and electrical properties acceptable for numerous applications. Especially for high volume products, the best solution often seems to be a combination of both materials. This fact raises the question of joining copper and aluminium. With respect to miniaturization laser micro welding is a very promising joining technique. Unfortunately, the metallurgical incompatibility of copper and aluminium easily results in the formation of brittle intermetallic phases and segregations during laser welding, thus generating an unacceptable quality of the joints. This paper presents investigations on enhancing the quality during laser micro welding of copper and aluminium for applications in electronics production. In order to eliminate the formation of brittle intermetallic phases, the addition of a filter material in form of a foil has been investigated. It can be shown that the addition of pure metals such as nickel and especially silver significantly reduces the occurrence of brittle phases in the joining area and therefore leads to an increase in welding quality. The proper control of the volume fractions of copper, aluminium and filler material in the melting zone helps to avoid materials segregation and reduces residual stress, consequently leading to a reduction of crack affinity and a stabilization of the mechanical and electrical properties.

  16. Synthesis of materials with infrared and ultraviolet lasers

    SciTech Connect

    Lyman, J.L.

    1988-01-01

    This paper discusses three divergent examples of synthesis of materials with lasers. The three techniques are: (1) infrared (CO/sub 2/) laser synthesis of silane (SiH/sub 4/) from disilane (Si/sub 2/H/sub 6/); (2) excimer (ArF) laser production of fine silicon powders from methyl- and chloro-substituted silanes; and, (3) excimer (KrF) laser production of fine metallic powders by laser ablation. The mechanism for each process is discussed along with some conclusions about the features of the laser radiation that enable each application. 19 refs., 12 figs., 2 tabs.

  17. Analysis of photoacoustic response from plasmonic nanostructures irradiated by ultrafast laser in water (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Hatef, Ali; Darvish, Behafarid; Dagallier, Adrien; Boutopoulos, Christos; Meunier, Michel

    2016-03-01

    Gold and silver plasmonic nanoparticles (NPs) are widely used as a contrast agent for photoacoustic (PA) imaging, taking advantage of the strong optical absorption cross-section of these particles due to their localized surface-plasmon resonance. Inspired by recent developments in ultra-high frequency wide-bandwidth transducers, we propose utilizing off-resonance ultrashort laser sources with a pulse width in the femtosecond (fs) and picosecond (ps) range to increase the efficiency of PA imaging. Also, from the fact that the laser pulse duration is shorter than the heat diffusion time of the materials, we expect practically no collateral damage of the laser irradiated biological tissues. Our preliminary studies show that irradiating the NPs with an ultrashort-pulsed laser has the potential to achieve substantially higher efficiency at generating the PA signal. Enhanced by the presence of NPs, the laser field causes a highly localized plasma nucleation around the vicinity of the NPs. Plasma relaxes through electron-ion interaction and releases a pressure wave in the surrounding medium. However, in this process, it is crucial to precisely control the heat energy absorption in the NPs to avoid their fragmentation. In this talk we present a model to simulate an optimized plasma-mediated PA signal dynamics generated from off-resonance ultrashort laser excitation (λ =800 nm, τ = 70 fs - 2 ps) of a variety of plasmonic NPs with sizes ranging from 50 nm to 100 nm.

  18. Past, present and future of laser fusion research

    SciTech Connect

    Yamanaka, C.

    1996-05-01

    The concept of laser fusion was devised very shortly after the invention of laser. In 1972, the Institute of Laser Engineering, Osaka University was established by the author in accordance with the Edward Teller{close_quote}s special lecture on {open_quote}{open_quote}New Internal Combustion Engine{close_quote}{close_quote} for IQEC at Montreal which predicted the implosion fusion. In 1975 we invented the so called indirect drive fusion concept {open_quote}{open_quote}Cannonball Target{close_quote}{close_quote} which became later to be recognize as a same concept of {open_quote}{open_quote}Hohlraum Target{close_quote}{close_quote} from Livermore. As well known, ICF research in the US had been veiled for a long time due to the defense classification. While researchers from Japan, Germany and elsewhere have concentrated the efforts to investigate the inertial fusion energy which seems to be very interesting for a future civil energy. They were publishing their own works not only on the direct implosion scheme but also the indirect implosion experiment. These advanced results often frustrated the US researchers who were not allowed to talk about the details of their works. In 1988, international members of the ICF research society including the US scientists gathered together at ECLIM to discuss the necessity of freedom in the ICF research and concluded to make a statement {open_quote}{open_quote}Madrid Manifest{close_quote}{close_quote} which requested the declassification of the ICF research internationally. After 6 years of halt, the US DOE decided to declassify portions of the program as a part of secretary Hazel O{close_quote}Leary{close_quote}s openness initiative. The first revealed presentation from the US was done at Seville 1994, which however were well known already. Classification impeded the progress by restricting the flow of information and did not allow the ICF work to compete by the open scientific security. (Abstract Truncated)

  19. Laser-induced damage in optical materials: sixteenth ASTM symposium.

    PubMed

    Bennett, H E; Guenther, A H; Milam, D; Newnam, B E

    1987-03-01

    The Sixteenth Annual Symposium on Optical Materials for High Power Lasers (Boulder Damage Symposium) was held at the National Bureau of Standards in Boulder, CO, 15-17 Oct. 1984. The Symposium was held under the auspices of ASTM Committee F-1, Subcommittee on Laser Standards, with the joint sponsorship of NBS, the Defense Advanced Research Project Agency, the Department of Energy, the Office of Naval Research, and the Air Force Office of Scientific Research. Approximately 180 scientists attended the Symposium, including representatives from England, France, The Netherlands, Scotland, and West Germany. The Symposium was divided into sessions concerning Materials and Measurements, Mirrors and Surfaces, Thin Films, and Fundamental Mechanisms. As in previous years, the emphasis of the papers presented at the Symposium was directed toward new frontiers and new developments. Particular emphasis was given to materials for high-power apparatus. The wavelength range of prime interest was from 10.6,microm to the UV region. Highlights included surface characterization, thin-film-substrate boundaries, and advances in fundamental laser-matter threshold interactions and mechanisms. Harold E. Bennett of the U.S. Naval Weapons Center, Arthur H. Guenther of the U.S. Air Force Weapons Laboratory, David Milam of the Lawrence Livermore National Laboratory, and Brian E. Newnam of the Los Alamos National Laboratory were cochairmen of the Symposium.

  20. An improved approach for process monitoring in laser material processing

    NASA Astrophysics Data System (ADS)

    König, Hans-Georg; Pütsch, Oliver; Stollenwerk, Jochen; Loosen, Peter

    2016-04-01

    Process monitoring is used in many different laser material processes due to the demand for reliable and stable processes. Among different methods, on-axis process monitoring offers multiple advantages. To observe a laser material process it is unavoidable to choose a wavelength for observation that is different to the one used for material processing, otherwise the light of the processing laser would outshine the picture of the process. By choosing a different wavelength, lateral chromatic aberration occurs in not chromatically corrected optical systems with optical scanning units and f-Theta lenses. These aberrations lead to a truncated image of the process on the camera or the pyrometer, respectively. This is the reason for adulterated measurements and non-satisfying images of the process. A new approach for solving the problem of field dependent lateral chromatic aberration in process monitoring is presented. Therefore, the scanner-based optical system is reproduced in a simulation environment, to predict the occurring lateral chromatic aberrations. In addition, a second deflecting system is integrated into the system. By using simulation, a predictive control is designed that uses the additional deflecting system to introduce reverse lateral deviations in order to compensate the lateral effect of chromatic aberration. This paper illustrates the concept and the implementation of the predictive control, which is used to eliminate lateral chromatic aberrations in process monitoring, the simulation on which the system is based the optical system as well as the control concept.

  1. Numerical analysis of the effects of non-conventional laser beam geometries during laser melting of metallic materials

    NASA Astrophysics Data System (ADS)

    Safdar, Shakeel; Li, Lin; Sheikh, M. A.

    2007-01-01

    Laser melting is an important industrial activity encountered in a variety of laser manufacturing processes, e.g. selective laser melting, welding, brazing, soldering, glazing, surface alloying, cladding etc. The majority of these processes are carried out by using either circular or rectangular beams. At present, the melt pool characteristics such as melt pool geometry, thermal gradients and cooling rate are controlled by the variation of laser power, spot size or scanning speed. However, the variations in these parameters are often limited by other processing conditions. Although different laser beam modes and intensity distributions have been studied to improve the process, no other laser beam geometries have been investigated. The effect of laser beam geometry on the laser melting process has received very little attention. This paper presents an investigation of the effects of different beam geometries including circular, rectangular and diamond shapes on laser melting of metallic materials. The finite volume method has been used to simulate the transient effects of a moving beam for laser melting of mild steel (EN-43A) taking into account Marangoni and buoyancy convection. The temperature distribution, melt pool geometry, fluid flow velocities and heating/cooling rates have been calculated. Some of the results have been compared with the experimental data.

  2. Ultrafast laser ablation of transparent materials

    NASA Astrophysics Data System (ADS)

    Bauer, Lara; Russ, Simone; Kaiser, Myriam; Kumkar, Malte; Faißt, Birgit; Weber, Rudolf; Graf, Thomas

    2016-03-01

    The present work investigates the influence of the pulse duration and the temporal spacing between pulses on the ablation of aluminosilicate glass by comparing the results obtained with pulse durations of 0.4 ps and 6 ps. We found that surface modifications occur already at fluences below the single pulse ablation threshold and that laser-induced periodic surface structures (LIPSS) emerge as a result of those surface modifications. For 0.4 ps the ablation threshold fluences is lower than for 6 ps. Scanning electron micrographs of LIPSS generated with 0.4 ps exhibit a more periodic and less coarse structure as compared to structures generated with 6 ps. Furthermore we report on the influence of temporal spacing between the pulses on the occurrence of LIPSS and the impact on the quality of the cutting edge. Keywords: LIPSS,

  3. Past, present and future of laser fusion research

    NASA Astrophysics Data System (ADS)

    Yamanaka, C.

    1996-05-01

    The concept of laser fusion was devised very shortly after the invention of laser. In 1972, the Institute of Laser Engineering, Osaka University was established by the author in accordance with the Edward Teller's special lecture on ``New Internal Combustion Engine'' for IQEC at Montreal which predicted the implosion fusion. In 1975 we invented the so called indirect drive fusion concept ``Cannonball Target'' which became later to be recognize as a same concept of ``Hohlraum Target'' from Livermore. As well known, ICF research in the US had been veiled for a long time due to the defense classification. While researchers from Japan, Germany and elsewhere have concentrated the efforts to investigate the inertial fusion energy which seems to be very interesting for a future civil energy. They were publishing their own works not only on the direct implosion scheme but also the indirect implosion experiment. These advanced results often frustrated the US researchers who were not allowed to talk about the details of their works. In 1988, international members of the ICF research society including the US scientists gathered together at ECLIM to discuss the necessity of freedom in the ICF research and concluded to make a statement ``Madrid Manifest'' which requested the declassification of the ICF research internationally. After 6 years of halt, the US DOE decided to declassify portions of the program as a part of secretary Hazel O'Leary's openness initiative. The first revealed presentation from the US was done at Seville 1994, which however were well known already. Classification impeded the progress by restricting the flow of information and did not allow the ICF work to compete by the open scientific security. The implosion experiments by GEKKO XII Osaka demonstrated a high temperature compression of DT fuel up to 10 keV, neutron yield 1013 and a high density compression of CDT hollow shell pellet to reach 1000 g/cm3 respectively. These results gave us a strong

  4. Transport of biologically active material in laser cutting.

    PubMed

    Frenz, M; Mathezloic, F; Stoffel, M H; Zweig, A D; Romano, V; Weber, H P

    1988-01-01

    The transport of biologically active material during laser cutting with CO2 and Er lasers is demonstrated. This transport mechanism removes particles from the surface of gelatin, agar, and liver samples into the depth of the laser-formed craters. The transport phenomenon is explained by a contraction and condensation of enclosed hot water vapor. We show by cultivating transported bacteria in agar that biological particles can survive the shock of the transport. Determination of the numbers of active cells evidences a more pronounced activity of the cultivated bacteria after impact with an Er laser than with a CO2 laser.

  5. Growth of Carbon Nanostructure Materials Using Laser Vaporization

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, Ching-Hua; Lehozeky, S.

    2000-01-01

    Since the potential applications of carbon nanotubes (CNT) was discovered in many fields, such as non-structure electronics, lightweight composite structure, and drug delivery, CNT has been grown by many techniques in which high yield single wall CNT has been produced by physical processes including arc vaporization and laser vaporization. In this presentation, the growth mechanism of the carbon nanostructure materials by laser vaporization is to be discussed. Carbon nanoparticles and nanotubes have been synthesized using pulsed laser vaporization on Si substrates in various temperatures and pressures. Two kinds of targets were used to grow the nanostructure materials. One was a pure graphite target and the other one contained Ni and Co catalysts. The growth temperatures were 600-1000 C and the pressures varied from several torr to 500 torr. Carbon nanoparticles were observed when a graphite target was used, although catalysts were deposited on substrates before growing carbon films. When the target contains catalysts, carbon nanotubes (CNT) are obtained. The CNT were characterized by scanning electron microscopy, x-ray diffraction, optical absorption and transmission, and Raman spectroscopy. The temperature-and pressure-dependencies of carbon nanotubes' growth rate and size were investigated.

  6. Laser materials processing of complex components. From reverse engineering via automated beam path generation to short process development cycles.

    NASA Astrophysics Data System (ADS)

    Görgl, R.; Brandstätter, E.

    2016-03-01

    The article presents an overview of what is possible nowadays in the field of laser materials processing. The state of the art in the complete process chain is shown, starting with the generation of a specific components CAD data and continuing with the automated motion path generation for the laser head carried by a CNC or robot system. Application examples from laser welding, laser cladding and additive laser manufacturing are given.

  7. Perovskite Materials for Light-Emitting Diodes and Lasers.

    PubMed

    Veldhuis, Sjoerd A; Boix, Pablo P; Yantara, Natalia; Li, Mingjie; Sum, Tze Chien; Mathews, Nripan; Mhaisalkar, Subodh G

    2016-08-01

    Organic-inorganic hybrid perovskites have cemented their position as an exceptional class of optoelectronic materials thanks to record photovoltaic efficiencies of 22.1%, as well as promising demonstrations of light-emitting diodes, lasers, and light-emitting transistors. Perovskite materials with photoluminescence quantum yields close to 100% and perovskite light-emitting diodes with external quantum efficiencies of 8% and current efficiencies of 43 cd A(-1) have been achieved. Although perovskite light-emitting devices are yet to become industrially relevant, in merely two years these devices have achieved the brightness and efficiencies that organic light-emitting diodes accomplished in two decades. Further advances will rely decisively on the multitude of compositional, structural variants that enable the formation of lower-dimensionality layered and three-dimensional perovskites, nanostructures, charge-transport materials, and device processing with architectural innovations. Here, the rapid advancements in perovskite light-emitting devices and lasers are reviewed. The key challenges in materials development, device fabrication, operational stability are addressed, and an outlook is presented that will address market viability of perovskite light-emitting devices.

  8. Perovskite Materials for Light-Emitting Diodes and Lasers.

    PubMed

    Veldhuis, Sjoerd A; Boix, Pablo P; Yantara, Natalia; Li, Mingjie; Sum, Tze Chien; Mathews, Nripan; Mhaisalkar, Subodh G

    2016-08-01

    Organic-inorganic hybrid perovskites have cemented their position as an exceptional class of optoelectronic materials thanks to record photovoltaic efficiencies of 22.1%, as well as promising demonstrations of light-emitting diodes, lasers, and light-emitting transistors. Perovskite materials with photoluminescence quantum yields close to 100% and perovskite light-emitting diodes with external quantum efficiencies of 8% and current efficiencies of 43 cd A(-1) have been achieved. Although perovskite light-emitting devices are yet to become industrially relevant, in merely two years these devices have achieved the brightness and efficiencies that organic light-emitting diodes accomplished in two decades. Further advances will rely decisively on the multitude of compositional, structural variants that enable the formation of lower-dimensionality layered and three-dimensional perovskites, nanostructures, charge-transport materials, and device processing with architectural innovations. Here, the rapid advancements in perovskite light-emitting devices and lasers are reviewed. The key challenges in materials development, device fabrication, operational stability are addressed, and an outlook is presented that will address market viability of perovskite light-emitting devices. PMID:27214091

  9. Laser materials for the 0.67-microns to 2.5-microns range

    NASA Technical Reports Server (NTRS)

    Toda, Minoru; Zamerowski, Thomas J.; Ladany, Ivan; Martinelli, Ramon U.

    1987-01-01

    Basic requirements for obtaining injection laser action in III-V semiconductors are discussed briefly. A detailed review is presented of materials suitable for lasers emitting at 0.67, 1.44, 1.93, and 2.5 microns. A general approach to the problem is presented, based on curves of materials properties published by Sasaki et al. It is also shown that these curves, although useful, may need correction in certain ranges. It is deduced that certain materials combinations, either proposed in the literature or actually tried, are not appropriate for double heterostructure lasers, because the refractive index of the cladding material is higher than the index of the active material, thus resulting in no waveguiding, and high threshold currents. Recommendations are made about the most promising approach to the achievement of laser action in the four wavelengths mentioned above.

  10. Laser balancing system for high material removal rates

    NASA Technical Reports Server (NTRS)

    Jones, M. G.; Georgalas, G.; Ortiz, A. L.

    1984-01-01

    A laser technique to remove material in excess of 10 mg/sec from a spinning rotor is described. This material removal rate is 20 times greater than previously reported for a surface speed of 30 m/sec. Material removal enhancement was achieved by steering a focused laser beam with moving optics to increase the time of laser energy interaction with a particular location on the circumferential surface of a spinning rotor. A neodymium:yttrium aluminum garnet (Nd:YAG) pulse laser was used in this work to evaluate material removal for carbon steel, 347 stainless steel, Inconal 718, and titanium 6-4. This technique is applicable to dynamic laser balancing.

  11. Laser-assisted dry etching of III-nitride wide band gap semiconductor materials

    NASA Astrophysics Data System (ADS)

    Leonard, Robert Tyler

    Laser assisted dry etching is a materials processing technique capable of producing highly anisotropic etch features with precise etch depth control and little contamination. The technique is simple: laser radiation is combined with a gaseous chemical etchant to remove material in pattern selected regions. The advantages of laser etching include the removal of etch products with photonic energy instead of ion bombardment, potential of projected patterning to combine growth and etching in situ without exposure to air, production of distinct sidewall etch features for device structures, and precise control of etching with a highly directional pulsed laser energy source. The use of pulsed laser radiation allows for pulsed etch depth control, ultimately resulting in atomic layer control. Laser assisted dry HCl etching of GaN, AlGaN and InGaN optical device materials was first demonstrated in our laboratory at North Carolina State University in a modified UHV vacuum chamber and ArF (193nm) excimer laser. Effective masking materials of Al and SiOsb2 were determined to be resistant to laser heating and HCl environment for laser etching. The process variables of laser intensity and HCl pressure were found to be dominant with the necessary condition that no etching occurs without both the excimer laser and HCl present. Successful laser etching of GaN, AlGaN, and InGaN was demonstrated indicating that deep etch features with distinct sidewall features are possible with this technique. Laser etching of a III-Nitride quantum well double heterostructure resulted in no degradation of the photoluminescence response. Also, reduction of etch damage with laser etching may be possible in comparison to ion etching. Finally, a proposed model for the etching mechanism includes the photothermal release of nitrogen from the GaN surface resulting in a Ga-rich surface which is removed by the HCl etchant.

  12. Effect of Moisture Content of Paper Material on Laser Cutting

    NASA Astrophysics Data System (ADS)

    Stepanov, Alexander; Saukkonen, Esa; Piili, Heidi; Salminen, Antti

    Laser technology has been used in industrial processes for several decades. The most advanced development and implementation took place in laser welding and cutting of metals in automotive and ship building industries. However, there is high potential to apply laser processing to other materials in various industrial fields. One of these potential fields could be paper industry to fulfill the demand for high quality, fast and reliable cutting technology. Difficulties in industrial application of laser cutting for paper industry are associated to lack of basic information, awareness of technology and its application possibilities. Nowadays possibilities of using laser cutting for paper materials are widened and high automation level of equipment has made this technology more interesting for manufacturing processes. Promising area of laser cutting application at paper making machines is longitudinal cutting of paper web (edge trimming). There are few locations at a paper making machine where edge trimming is usually done: wet press section, calender or rewinder. Paper web is characterized with different moisture content at different points of the paper making machine. The objective of this study was to investigate the effect of moisture content of paper material on laser cutting parameters. Effect of moisture content on cellulose fibers, laser absorption and energy needed for cutting is described as well. Laser cutting tests were carried out using CO2 laser.

  13. Refractive beam shapers for material processing with high power single mode and multimode lasers

    NASA Astrophysics Data System (ADS)

    Laskin, Alexander; Laskin, Vadim

    2013-02-01

    The high power multimode fiber-coupled laser sources, like solid state lasers or laser diodes as well as single mode and multimode fiber lasers, are now widely used in various industrial laser material processing technologies like metal or plastics welding, cladding, hardening, brazing, annealing. Performance of these technologies can be essentially improved by varying the irradiance profile of a laser beam with using beam shaping optics, for example, the field mapping refractive beam shapers like piShaper. Operational principle of these devices presumes transformation of laser beam irradiance distribution from Gaussian to flattop, super-Gauss, or inverse-Gauss profile with high flatness of output wave front, conserving of beam consistency, providing collimated output beam of low divergence, high transmittance, extended depth of field. Important feature of piShaper is in capability to operate with TEM00 and multimode lasers, the beam shapers can be implemented not only as telescopic optics but also as collimating systems, which can be connected directly to fiber-coupled lasers or fiber lasers, thus combining functions of beam collimation and irradiance transformation. This paper will describe some features of beam shaping of high-power laser sources, including multimode fiber coupled lasers, and ways of adaptation of beam shaping optical systems design to meet requirements of modern laser technologies. Examples of real implementations will be presented as well.

  14. Laser processing for manufacturing nanocarbon materials

    NASA Astrophysics Data System (ADS)

    Van, Hai Hoang

    CNTs have been considered as the excellent candidate to revolutionize a broad range of applications. There have been many method developed to manipulate the chemistry and the structure of CNTs. Laser with non-contact treatment capability exhibits many processing advantages, including solid-state treatment, extremely fast processing rate, and high processing resolution. In addition, the outstanding monochromatic, coherent, and directional beam generates the powerful energy absorption and the resultant extreme processing conditions. In my research, a unique laser scanning method was developed to process CNTs, controlling the oxidation and the graphitization. The achieved controllability of this method was applied to address the important issues of the current CNT processing methods for three applications. The controllable oxidation of CNTs by laser scanning method was applied to cut CNT films to produce high-performance cathodes for FE devices. The production method includes two important self-developed techniques to produce the cold cathodes: the production of highly oriented and uniformly distributed CNT sheets and the precise laser trimming process. Laser cutting is the unique method to produce the cathodes with remarkable features, including ultrathin freestanding structure (~200 nm), greatly high aspect ratio, hybrid CNT-GNR emitter arrays, even emitter separation, and directional emitter alignment. This unique cathode structure was unachievable by other methods. The developed FE devices successfully solved the screening effect issue encounter by current FE devices. The laser-control oxidation method was further developed to sequentially remove graphitic walls of CNTs. The laser oxidation process was directed to occur along the CNT axes by the laser scanning direction. Additionally, the oxidation was further assisted by the curvature stress and the thermal expansion of the graphitic nanotubes, ultimately opening (namely unzipping) the tubular structure to

  15. Present state of applying diode laser in Toyota Motor Corp.

    NASA Astrophysics Data System (ADS)

    Terada, Masaki; Nakamura, Hideo

    2003-03-01

    Since the mid-1980s, Toyota Motor Corporation has applied CO2 lasers and YAG lasers to machine (welding, piercing, cutting, surface modifying etc.) automobile parts. In recent years diode lasers, which are excellent in terms of cost performance, are now available on the market as a new type of oscillator and are expected to bring about a new age in laser technology. Two current problems with these lasers, however, are the lack of sufficient output and the difficulty in improving the focusing the beam, which is why it has not been easy to apply them to the machining of metal parts in the past. On the other hand, plastics can be joined with low energy because they have a lower melting point than metal and the rate of absorption of the laser is easy to control. Moreover, because the high degree of freedom in molding plastic parts results in many complex shapes that need to be welded, Toyota is looking into the use of diode lasers to weld plastic parts. This article will introduce the problems of plastics welding and the methods to solve them referring to actual examples.

  16. Monitoring femtosecond laser microscopic photothermolysis with multimodal microscopy (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Huang, Yimei; Lui, Harvey; Zhao, Jianhua; McLean, David I.; Zeng, Haishan

    2016-02-01

    Photothermolysis induced by femtosecond (fs) lasers may be a promising modality in dermatology because of its advantages of high precision due to multiphoton absorption and deeper penetration due to the use of near infrared wavelengths. Although multiphoton absorption nonlinear effects are capable of precision targeting, the femtosecond laser photothermolysis could still have effects beyond the targeted area if a sufficiently high dose of laser light is used. Such unintended effects could be minimized by real time monitoring photothermolysis during the treatment. Targeted photothermolytic treatment of ex vivo mouse skin dermis was performed with tightly focused fs laser beams. Images of reflectance confocal microscopy (RCM), second harmonic generation (SHG), and two-photon fluorescence (TPF) of the mouse skins were obtained with integrated multimodal microscopy before, during, and after the laser treatment. The RCM, SHG, and TPF signal intensities of the treatment areas changed after high power femtosecond laser irradiation. The intensities of the RCM and SHG signals decreased when the tissue was damaged, while the intensity of the TPF signal increased when the photothermolysis was achieved. Moreover, the TPF signal was more susceptible to the degree of the photothermolysis than the RCM and SHG signals. The results suggested that multimodal microscopy is a potentially useful tool to monitor and assess the femtosecond laser treatment of the skin to achieve microscopic photothermolysis with high precision.

  17. Nonstoichiometric Laser Materials: Designer Wavelengths in Neodymium Doped Garnets

    NASA Technical Reports Server (NTRS)

    Walsh, Brian M.; Barnes, Norman P.

    2008-01-01

    The tunable nature of lasers provides for a wide range of applications. Most applications rely on finding available laser wavelengths to meet the needs of the research. This article presents the concept of compositional tuning, whereby the laser wavelength is designed by exploiting nonstoichiometry. For research where precise wavelengths are required, such as remote sensing, this is highly advantageous. A theoretical basis for the concept is presented and experimental results in spectroscopic measurements support the theoretical basis. Laser operation nicely demonstrates the validity of the concept of designer lasers.

  18. Progress Toward Roll Processing of Solar Reflective Material (Presentation)

    SciTech Connect

    Smilgys, R.; Wallace, S.; Kennedy, C.

    2001-04-01

    This presentation discusses the goal of this project which was to demonstrate that it is possible to cost-effectively produce high performance solar reflective material using vacuum deposition techniques.

  19. Laser induced damage in optical materials: 8th ASTM symposium.

    PubMed

    Glass, A J; Guenther, A H

    1977-05-01

    The Eighth Annual Symposium on Optical Materials for High Power Lasers (Boulder Damage Symposium) was hosted by the National Bureau of Standards in Boulder, Colorado, from 13 to 15 July 1976. The Symposium was held under the auspices of ASTM Committee F-1, Subcommittee on Laser Standards, with the joint sponsorship of NBS, the Defense Advanced Research Project Agency, the Energy Research and Development Administration, and the Office of Naval Research. About 160 scientists attended the Symposium, including representatives of the United Kingdom, France, Canada, and Brazil. The Symposium was divided into five half-day sessions concerning Bulk Material Properties and Thermal Behavior, Mirrors and Surfaces, Thin Film Properties, Thin Film Damage, and Scaling Laws and Fundamental Mechanisms. As in previous years, the emphasis of the papers presented at the Symposium was directed toward new frontiers and new developments. Particular emphasis was given to new materials for use at 10.6 microm in mirror substrates, windo s, and coatings. New techniques in film deposition and advances in diamond-turning of optics were described. The scaling of damage thresholds with pulse duration, focal area, and wavelength were discussed. Alexander J. Glass of Lawrence Livermore Laboratory and Arthur H. Guenther of the Air Force Weapons Laboratory were co-chairpersons of the Symposium. The Ninth Annual Symposium is scheduled for 4-6 October 1977 at the National Bureau of Standards, Boulder, Colorado.

  20. Laser -Based Joining of Metallic and Non-metallic Materials

    NASA Astrophysics Data System (ADS)

    Padmanabham, G.; Shanmugarajan, B.

    Laser as a high intensity heat source can be effectively used for joining of materials by fusion welding and brazing in autogenous or in hybrid modes. In autogenous mode, welding is done in conduction , deep penetration , and keyhole mode. However, due to inherently high energy density available from a laser source, autogenous keyhole welding is the most popular laser welding mode. But, it has certain limitations like need for extremely good joint fit-up, formation of very hard welds in steel , keyhole instability, loss of alloying elements, etc. To overcome these limitations, innovative variants such as laser-arc hybrid welding , induction-assisted welding , dual beam welding , etc., have been developed. Using laser heat, brazing can be performed by melting a filler to fill the joints, without melting the base materials. Accomplishing laser-based joining as mentioned above requires appropriate choice of laser source, beam delivery system, processing head with appropriate optics and accessories. Basic principles of various laser-based joining processes, laser system technology, process parameters, metallurgical effects on different base materials, joint performance, and applications are explained in this chapter.

  1. Reaction bonded silicon carbide material characteristics as related to its use in high power laser systems

    NASA Astrophysics Data System (ADS)

    Pitschman, Matthew; Miller, Travis; Hedges, Alan R.; Rummel, Steve

    2014-09-01

    Reaction bonded silicon carbide (RB SiC) is a durable material that is well-suited for use as a high power laser mirror substrate. The reaction bonded material has a low mass density, a high Young's Modulus, good thermal conductivity, and a very low coefficient of thermal expansion. All of these properties are beneficial in mirror substrates used in multikilowatt lasers. In conjunction with the development of RB SiC, special polishing processes, fabrication processes, and coatings have also been developed. In this paper we will present a comparison of the material properties of RB SiC and other mirror materials currently used in high power lasers. A brief overview of the critical fabrication and coating processes will also be reviewed. Finally, we will present thermal heat load test data showing the surface deformation of various high power mirrors used under heat loads typically found in laser systems operating at average powers greater than 10 kilowatts.

  2. Vertical-cavity surface-emitting lasers: present and future

    NASA Astrophysics Data System (ADS)

    Morgan, Robert A.

    1997-04-01

    This manuscript reviews the present status of 'commercial- grade,' state-of-the-art planar, batch-fabricable, vertical- cavity surface-emitting lasers (VCSELs). Commercial-grade performance on all fronts for high-speed data communications is clearly established. In discussing the 'present,' we focus on the entrenched proton-implanted AlGaAs-based (emitting near 850 nm) technology. Renditions of this VCSEL design exist in commercial products and have enabled numerous application demonstrations. Our designs more than adequately meet producibility, performance, and robustness stipulations. Producibility milestones include greater than 99% device yield across 3-in-dia metal-organic vapor phase epitaxy (MOVPE)-grown wafers and wavelength operation across greater than 100-nm range. Progress in performance includes the elimination of the excessive voltage-drop that plagued VCSELs as recently as 2 to 3 years ago. Threshold voltages as low as Vth equals 1.53 V (and routinely less than 1.6 V) are now commonplace. Submilliamp threshold currents (Ith equals 0.68 mA) have even been demonstrated with this planar structure. Moreover, continuous wave (cw) power Pcw greater than 59 mW and respectable wall-plug efficiencies ((eta) wp equals 28%) have been demonstrated. VCSEL robustness is evidenced by maximum cw lasing temperature T equals 200 degrees Celsius and temperature ranges of 10 K to 400 K and minus 55 degrees Celsius to 155 degrees Celsius on a single VCSEL. These characteristics should enable great advances in VCSEL-based technologies and beckon the notion that 'commercial-grade' VCSELs are viable in cryogenic and avionics/military environments. We also discuss what the future may hold in extensions of this platform to different wavelengths, increased integration, and advanced structures. This includes low-threshold, high- speed, single-mode VCSELs, hybrid VCSEL transceivers, and self-pulsating VCSELs.

  3. Latest developments of ultrafast fiber laser and its material applications

    NASA Astrophysics Data System (ADS)

    Cho, G. C.; Liu, B.; Shah, L.; Liu, Z.; Che, Y.; Xu, J.

    2009-02-01

    We address recent fiber-based femtosecond laser technology. Specifically, fiber-chirped pulse amplifier is discussed for the enabling the concept of real-world applications. We review recent selected material applications demonstrating advantages of ultrafast dynamics of highly repetitive pulse train in nanoparticle generation in pulsed-laser deposition and reliable Si wafer singulation.

  4. Research of metallic materials irradiation with high energy pulsed laser impact

    NASA Astrophysics Data System (ADS)

    Blesman, A. I.; Postnikov, D. V.; Seropyan, G. M.; Tkachenko, E. A.; Teplouhov, A. A.; Polonyankin, D. A.

    2016-02-01

    In the process of metallic materials treatment by pulsed laser beams with nanosecond duration occurs extremely rapid and intensive heating of their surface. In this case a thin surface layer of material is heated to the boiling point and rapidly evaporates. This leads to arising substantial forces of reactive nature which significantly influence on the shape of the solidified melt and in some cases may cause deformation of the underlying layers. The considered question is relevant in the research of precision treatment of miniature products by laser beams. A metallic powder with microfine material structure was selected as the object of research and was exposed to laser irradiation with nanosecond duration. At the core of reactive forces calculation used the approach similar for laser rocket engines. The paper also presents the model and the results of the forces and the reactive recoil impulse calculation occurring during laser impact to the microfine metallic powder.

  5. Laser induced damage in optical materials: eleventh ASTM symposium.

    PubMed

    Bennett, H E; Glass, A J; Guenther, A H; Newnam, B

    1980-07-15

    The eleventh Symposium on Optical Materials for High-Power Lasers (Boulder Damage Symposium) was held at the National Bureau of Standards in Boulder, Colorado, 30-31 October 1979. The symposium was held under the auspices of ASTM Committee F-1, Subcommittee on Laser Standards, with the joint sponsorship of NBS, the Defense Advanced Research Projects Agency, the Department of Energy, and the Office of Naval Research. About 150 scientists attended the symposium, including representatives of the United Kingdom, France, Canada, Japan, West Germany, and Denmark. The symposium was divided into sessions concerning transparent optical materials and the measurement of their properties, mirrors and surfaces, thin film characteristics, thin film damage, considerations for high-power systems, and finally theory and breakdown. As in previous years, the emphasis of the papers presented at the symposium was directed toward new frontiers and new developments. Particular emphasis was given to materials for high-power apparatus. The wavelength range of prime interest was from 10.6 microm to the UV region. Highlights included surface characterization, thin film-substrate boundaries, and advances in fundamental laser-matter threshold interactions and mechanisms. The scaling of damage thresholds with pulse duration, focal area, and wavelength was discussed in detail. Harold E. Bennett of the Naval Weapons Center, Alexander J. Glass of the Lawrence Livermore Laboratory, Arthur H. Guenther of the Air Force Weapons Laboratory, and Brian E. Newnam of the Los Alamos Scientific Laboratory were cochairpersons. The twelfth annual symposium is scheduled for 30 September-1 October 1980 at the National Bureau of Standards, Boulder, Colorado.

  6. Laser induced damage in optical materials: twelfth ASTM symposium.

    PubMed

    Bennett, H E; Glass, A J; Guenther, A H; Newnam, B

    1981-09-01

    The twelfth annual Symposium on Optical Materials for High Power Lasers (Boulder Damage Symposium) was held at the National Bureau of Standards in Boulder, Colorado, 30 Sept.-l Oct., 1980. The symposium was held under the auspices of ASTM Committee F-l, Subcommittee on Laser Standards, with the joint sponsorship of NBS, the Defense Advanced Research Projects Agency, the Department of Energy, the Office of Naval Research, and the Air Force Office of Scientific research. Over 150 scientists attended the symposium, including representatives of the United Kingdom, France, Japan, and West Germany. The symposium was divided into sessions concerning materials and measurements, mirrors and surfaces, thin films, and finally fundamental mechanisms. As in previous years, the emphasis of the papers presented at the symposium was directed toward new frontiers and new developments. Particular emphasis was given to materials for high power systems. The wavelength range of prime interest was from 10.6 microm to the UV region. Highlights included surface characterization, thin film-substrate boundaries, and advances in fundamental laser-matter threshold interactions and mechanisms. The scaling of damage thresholds with pulse duration, focal area, and wavelength was discussed in detail. Harold E. Bennett of the Naval Weapons Center, Alexander J. Glass of the Lawrence Livermore National Laboratory, Arthur H. Guenther of the Air Force Weapons Laboratory, and Brian E. Newnam of the Los Alamos National Laboratory were cochairmen of the symposium. The thirteenth annual symposium is scheduled for 17-18 Nov. 1981 at the National Bureau of Standards, Boulder, Colorado.

  7. Joining of materials using laser heating

    DOEpatents

    Cockeram, Brian V.; Hicks, Trevor G.; Schmid, Glenn C.

    2003-07-01

    A method for diffusion bonding ceramic layers such as boron carbide, zirconium carbide, or silicon carbide uses a defocused laser beam to heat and to join ceramics with the use of a thin metal foil insert. The metal foil preferably is rhenium, molybdenum or titanium. The rapid, intense heating of the ceramic/metal/ceramic sandwiches using the defocused laser beam results in diffusive conversion of the refractory metal foil into the ceramic and in turn creates a strong bond therein.

  8. Review of laser filter materials. Final report, October 1987-September 1988

    SciTech Connect

    Welch, J.A.

    1989-09-26

    This report presents a discussion of laser eye-protection filtering materials. Four classes of filters are evaluated for immediate and future filtering capabilities. Salient features required for near-term multi-wavelength filtering are discussed in general, and the effectiveness of several filter materials as laser protection is assessed. Spectral illuminances for the most promising eye-protection filters are computed for representative day- and night-lighting conditions to approximate visual acuity.

  9. Millisecond laser machining of transparent materials assisted by a nanosecond laser with different delays.

    PubMed

    Pan, Yunxiang; Lv, Xueming; Zhang, Hongchao; Chen, Jun; Han, Bing; Shen, Zhonghua; Lu, Jian; Ni, Xiaowu

    2016-06-15

    A millisecond laser combined with a nanosecond laser was applied to machining transparent materials. The influences of delay between the two laser pulses on processing efficiencies and modified sizes were studied. In addition, a laser-supported combustion wave (LSCW) was captured during laser irradiation. An optimal delay corresponding to the highest processing efficiency was found for cone-shaped cavities. The modified size as well as the lifetime and intensity of the LSCW increased with the delay decreasing. Thermal cooperation effects of defects, overlapping effects of small modified sites, and thermal radiation from LSCW result in all the phenomena. PMID:27304294

  10. Millisecond laser machining of transparent materials assisted by a nanosecond laser with different delays.

    PubMed

    Pan, Yunxiang; Lv, Xueming; Zhang, Hongchao; Chen, Jun; Han, Bing; Shen, Zhonghua; Lu, Jian; Ni, Xiaowu

    2016-06-15

    A millisecond laser combined with a nanosecond laser was applied to machining transparent materials. The influences of delay between the two laser pulses on processing efficiencies and modified sizes were studied. In addition, a laser-supported combustion wave (LSCW) was captured during laser irradiation. An optimal delay corresponding to the highest processing efficiency was found for cone-shaped cavities. The modified size as well as the lifetime and intensity of the LSCW increased with the delay decreasing. Thermal cooperation effects of defects, overlapping effects of small modified sites, and thermal radiation from LSCW result in all the phenomena.

  11. Damage testing of sapphire and Ti: sapphire laser materials

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Diffusion bonded sapphire and Ti (Titanium). Sapphire laser materials that will be damage tested to determine if there is an increase in damage threshold. Photographed in building 1145, photographic studio.

  12. Yb:FAP and related materials, laser gain medium comprising same, and laser systems using same

    DOEpatents

    Krupke, William F.; Payne, Stephen A.; Chase, Lloyd L.; Smith, Larry K.

    1994-01-01

    An ytterbium doped laser material remarkably superior to all others, including Yb:YAG, comprises Ytterbium doped apatite (Yb:Ca.sub.5 (PO.sub.4).sub.3 F) or Yb:FAP, or ytterbium doped crystals that are structurally related to FAP. The new laser material is used in laser systems pumped by diode pump sources having an output near 0.905 microns or 0.98 microns, such as InGaAs and AlInGaAs, or other narrowband pump sources near 0.905 microns or 0.98 microns. The laser systems are operated in either the conventional or ground state depletion mode.

  13. Study of underwater laser propulsion using different target materials.

    PubMed

    Qiang, Hao; Chen, Jun; Han, Bing; Shen, Zhong-Hua; Lu, Jian; Ni, Xiao-Wu

    2014-07-14

    In order to investigate the influence of target materials, including aluminum (Al), titanium (Ti) and copper (Cu), on underwater laser propulsion, the analytical formula of the target momentum IT is deduced from the enhanced coupling theory of laser propulsion in atmosphere with transparent overlay metal target. The high-speed photography method and numerical simulation are employed to verify the IT model. It is shown that the enhanced coupling theory, which was developed originally for laser propulsion in atmosphere, is also applicable to underwater laser propulsion with metal targets.

  14. Vitamin C for stabilising biological lasers (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Kar, Ajoy K.; Mackenzie, Mark D.; Cialowicz, Katarzyna I.; Saleeb, Rebecca S.; Duncan, Rory R.

    2016-04-01

    We report on efforts to improve the lifetime of biological lasers through the use of ascorbic acid (also commonly known as vitamin C). Fluorescent proteins and dyes, used in biological lasers, suffer from photobleaching due to the build-up of reactive oxygen species (ROS) which causes damage leading to a decrease in emission over time. This is an issue both for laser lifetime and cell health. It has previously been shown that ascorbic acid can be effective in reducing ROS levels in a variety of applications. For our experiments human embryonic kidney cells (HEK293), containing the fluorescent dye Calcein AM, were placed between two dielectric plane mirrors to form a laser cavity. The cells were pumped using the output of a Ti:Sapphire femtosecond OPO system, frequency doubled twice in BBO crystals, giving an output of 474 nm. Initial results have shown an increase in laser lifetime when ascorbic acid is added to cells indicating a reduction in the build-up of ROS.

  15. Characterization of polymer materials and powders for selective laser melting

    NASA Astrophysics Data System (ADS)

    Wudy, K.; Drummer, D.; Drexler, M.

    2014-05-01

    Concerning individualization, the requirements to products have increased. The trend towards individualized serial products faces manufacturing techniques with demands of increasing flexibility. Additive manufacturing techniques generate components directly out of a CAD data set while requiring no specific tool or form. Due to this additive manufacturing processes comply, in opposite to conventional techniques, with these increased demands on processing technology. With a variety of available additive manufacturing techniques, some of them have a high potential to generate series products with reproducible properties. Selective laser melting (SLM) of powder materials shows the highest potential for this application. If components made by SLM are desired to be applied in technical series products, their achievable properties play a major part. These properties are mainly determined by the processed materials. The range of present commercially available materials for SLM of polymer powders is limited. This paper shows interrelations of various material properties to create a basic understanding of sintering processes and additional qualifying new materials. Main properties of polymer materials, with regard to their consolidation are viscosity and surface energy. On the one hand the difference of the surface energy between powder and melt influences, the wetting behavior, and thus the penetration depth. On the other hand, a high surface tension is fundamental for good coalescence of bordering particles. To fulfill these requirements limits of the surface tension will be determined on the basis of a reference material. For these reason methods for determining surface tension of solids, powders and melts are analyzed, to carry out a possible process-related material characterization. Not only an insight into observed SLM phenomena is provided but also hints concerning suitable material selection.

  16. Cr/sup 3+/-doped colquiriite solid state laser material

    SciTech Connect

    Payne, S.A.; Chase, L.L.; Newkirk, H.W.; Krupke, W.F.

    1989-03-07

    Chromium doped colquiriite, LiCaAlF/sub 6/:Cr/sup 3+/, is useful as a tunable laser crystal that has a high intrinsic slope efficiency, comparable to or exceeding that of alexandrite, the current leading performer of vibronic sideband Cr/sup 3+/ lasers. The laser output is tunable from at least 720 nm to 840 nm with a measured slope efficiency of about 60% in a Kr laser pumped laser configuration. The intrinsic slope efficiency (in the limit of large output coupling) may approach the quantum defect limited value of 83%. The high-slope efficiency implies that excited state absorption (ESA) is negligible. The potential for efficiency and the tuning range of this material satisfy the requirements for a pump laser for a high density storage medium incorporating Nd/sup 3+/ or Tm/sup 3+/ for use in a multimegajoule single shot fusion research facility.

  17. Cr.sup.3+ -doped colquiriite solid state laser material

    DOEpatents

    Payne, Stephen A.; Chase, Lloyd L.; Newkirk, Herbert W.; Krupke, William F.

    1989-01-01

    Chromium doped colquiriite, LiCaAlF.sub.6 :Cr.sup.3+, is useful as a tunable laser crystal that has a high intrinsic slope efficiency, comparable to or exceeding that of alexandrite, the current leading performer of vibronic sideband Cr.sup.3+ lasers. The laser output is tunable from at least 720 nm to 840 nm with a measured slop efficiency of about 60% in a Kr laser pumped laser configuration. The intrinsic slope efficiency (in the limit of large output coupling) may approach the quantum defect limited value of 83%. The high slope efficiency implies that excited state absorption (ESA) is negligible. The potential for efficiency and the tuning range of this material satisfy the requirements for a pump laser for a high density storage medium incorporating Nd.sup.3+ or Tm.sup.3+ for use in a multimegajoule single shot fusion research facility.

  18. Cr/sup 3 +/-doped colquiriite solid state laser material

    DOEpatents

    Payne, S.A.; Chase, L.L.; Newkirk, H.W.; Krupke, W.F.

    1988-03-31

    Chromium doped colquiriite, LiCaAlF/sub 6/:Cr/sup 3 +/, is useful as a tunable laser crystal that has a high intrinsic slope efficiency, comparable to or exceeding that of alexandrite, the current leading performer of vibronic sideband Cr/sup 3 +/ lasers. The laser output is tunable from at least 720 nm to 840 nm with a measured slope efficiency of about 60% in a Kr laser pumped laser configuration. The intrinsic slope efficiency (in the limit of large output coupling) may approach the quantum defect limited value of 83%. The high slope efficiency implies that excited state absorption (ESA) is negligible. The potential for efficiency and the tuning range of this material satisfy the requirements for a pump laser for a high density storage medium incorporating Nd/sup 3 +/ or Tm/sup 3 +/ for use in a multimegajoule single shot fusion research facility. 4 figs.

  19. Recent results from material processing studies on new generation lasers

    SciTech Connect

    Kautz, D.D.; Dragon, E.P.; Werve, M.E.; Hargrove, R.S.

    1993-12-09

    High power and radiance dye lasers developed at Lawrence Livermore National Laboratory show promise for material processing tasks. Evaluation using welding heat flow models suggests significant increases in precision and speed are expected. We started processing studies to determine the viability of these lasers for cutting and drilling. Titanium and stainless steel alloys were chosen as materials for the preliminary studies. Results show that cuts and holes with extremely fine features can be made with dye and copper-vapor lasers. High radiance beams produce low distortion and small heat affected zones. We have accomplished very high aspect ratios and micron scale kerfs and holes in both stainless steel and titanium alloys.

  20. Technology Assessment of Laser-Assisted Materials Processing in Space

    NASA Technical Reports Server (NTRS)

    Nagarathnam, Karthik; Taminger, Karen M. B.

    2001-01-01

    Lasers are useful for performing operations such as joining, machining, built-up freeform fabrication, shock processing, and surface treatments. These attributes are attractive for the supportability of longer-term missions in space due to the multi-functionality of a single tool and the variety of materials that can be processed. However, current laser technology also has drawbacks for space-based applications, specifically size, power efficiency, lack of robustness, and problems processing highly reflective materials. A review of recent laser developments will be used to show how these issues may be reduced and indicate where further improvement is necessary to realize a laser-based materials processing capability in space. The broad utility of laser beams in synthesizing various classes of engineering materials will be illustrated using state-of-the art processing maps for select lightweight alloys typically found on spacecraft. With the advent of recent breakthroughs in diode-pumped solid-state lasers and fiber optic technologies, the potential to perform multiple processing techniques is increasing significantly. Lasers with suitable wavelengths and beam properties have tremendous potential for supporting future space missions to the moon, Mars and beyond.

  1. Ultrafast dynamic ellipsometry and spectroscopy of laser shocked materials

    SciTech Connect

    Bolme, Cynthia A; Mc Grane, Shawn D; Dang, Nhan C; Whitley, Von H; Moore, David S.

    2011-01-20

    Ultrafast dynamic ellipsometry is used to measure the material motion and changes in the optical refractive index of laser shock compressed materials. This diagnostic has shown us that the ultrafast laser driven shocks are the same as shocks on longer timescales and larger length scales. We have added spectroscopic diagnostics of infrared absorption, ultra-violet - visible transient absorption, and femtosecond stimulated Raman scattering to begin probing the initiation chemistry that occurs in shock reactive materials. We have also used the femtosecond stimulated Raman scattering to measure the vibrational temperature of materials using the Stokes gain to anti-Stokes loss ratio.

  2. Femtosecond laser processing of fuel injectors - a materials processing evaluation

    SciTech Connect

    Stuart, B C; Wynne, A

    2000-12-16

    Lawrence Livermore National Laboratory (LLNL) has developed a new laser-based machining technology that utilizes ultrashort-pulse (0.1-1.0 picosecond) lasers to cut materials with negligible generation of heat or shock. The ultrashort pulse laser, developed for the Department of Energy (Defense Programs) has numerous applications in operations requiring high precision machining. Due to the extremely short duration of the laser pulse, material removal occurs by a different physical mechanism than in conventional machining. As a result, any material (e.g., hardened steel, ceramics, diamond, silicon, etc.) can be machined with minimal heat-affected zone or damage to the remaining material. As a result of the threshold nature of the process, shaped holes, cuts, and textures can be achieved with simple beam shaping. Conventional laser tools used for cutting or high-precision machining (e.g., sculpting, drilling) use long laser pulses (10{sup -8} to over 1 sec) to remove material by heating it to the melting or boiling point (Figure 1.1a). This often results in significant damage to the remaining material and produces considerable slag (Figure 1.2a). With ultrashort laser pulses, material is removed by ionizing the material (Figure 1.1b). The ionized plasma expands away from the surface too quickly for significant energy transfer to the remaining material. This distinct mechanism produces extremely precise and clean-edged holes without melting or degrading the remaining material (Figures 1.2 and 1.3). Since only a very small amount of material ({approx} <0.5 microns) is removed per laser pulse, extremely precise machining can be achieved. High machining speed is achieved by operating the lasers at repetition rates up to 10,000 pulses per second. As a diagnostic, the character of the short-pulse laser produced plasma enables determination of the material being machined between pulses. This feature allows the machining of multilayer materials, metal on metal or metal on

  3. ARPA solid state laser and nonlinear materials program. Final report

    SciTech Connect

    Moulton, P.F.

    1994-06-01

    The Research Division of Schwartz Electro-Optics, as part of the ARPA Solid State Laser and Nonlinear Materials Program, conducted a three-year study Erbium-Laser-Based Infrared Sources. The aim of the study was to improve the understanding of semiconductor-laser-pumped, infrared (IR) solid state lasers based on the trivalent rare-earth ion erbium (Er) doped into a variety of host crystals. The initial program plan emphasized operation of erbium-doped materials on the 2.8-3.0 micrometers laser transition. Pulsed, Q-switched sources using that transition, when employed as a pump source for parametric oscillators, can provide tunable mid-IR energy. The dynamics of erbium lasers are more complex than conventional neodymium (Nd)-doped lasers and they intended to use pump-probe techniques to measure the level and temporal behavior of gain in various materials. To do so they constructed a number of different cw Er-doped lasers as probe sources and employed the Cr:LiSAF(LiSrAlF6) laser as a pulsed pump source that would simulate pulsed diode arrays. The authors identified the 970-nm wavelength pump band of Er as the most efficient and were able to make use of recently developed cw and pulsed InGaAs strained-quantum-well diode lasers in the effort. At the conclusion of the program they demonstrated the first pulsed diode bar pumping of the most promising materials for pulsed operation, the oxide garnets YSGG and GGG and the fluoride BaY2F8.

  4. Laser materials processing applications at Lawrence Livermore National Laboratory

    SciTech Connect

    Hargrove, R.S.; Dragon, E.P.; Hackel, R.P.; Kautz, D.D.; Warner, B.E.

    1993-02-25

    High power and high radiance laser technologies developed at Lawrence Livermore National Laboratory (LLNL) such as copper-vapor lasers, solid-state slab lasers, dye lasers, harmonic wavelength conversion of these lasers, and fiber optic delivery systems show great promise for material processing tasks. Evaluation of models suggests significant potential for tenfold increases in welding, cutting, and drilling performance, as well as capability for applications in emerging technologies such as micromachining, surface treatment, and stereolithography. The goals of this program are to develop low-cost, reliable and maintainable industrial laser systems. Chains of copper lasers currently operate at more than 1.5 kW output and achieve mean time between failures of more than 1,000 hours. The beam quality of copper vapor lasers is approximately three times the diffraction limit. Dye lasers have near diffraction limited beam quality at greater than 1.0 kW. diode laser pumped, Nd:YAG slab lasers are also being developed at LLNL. Current designs achieve powers of greater than 1.0 kW and projected beam quality is in the two to five times diffraction limited range. Results from cutting and drilling studies in titanium and stainless steel alloys show that cuts and holes with extremely fine features can be made with dye and copper-vapor lasers. High radiance beams produce low distortion and small heat-affected zones. The authors have accomplished very high aspect ratio holes in drilling tests (> 60:1) and features with micron scale (5-50 {mu}m) sizes. Other, traditionally more difficult, materials such as copper, aluminum and ceramics will soon be studied in detail.

  5. New Polymer Materials for the Laser Sintering Process: Polypropylene and Others

    NASA Astrophysics Data System (ADS)

    Wegner, Andreas

    Laser sintering of polymers gets more and more importance for small series production. However, there is only a little number of materials available for the process. In most cases parts are build up using polyamide 12 or polyamide 11. Reasons for that are high prices, a restricted availability, poor mechanical part properties or an insufficient understanding of the processing of other materials. These problems result from the complex processing conditions in laser sintering with high requirements on the material's characteristics. Within this area, at the chair for manufacturing technology fundamental knowledge was established. Aim of the presented study was to qualify different polymers for the laser sintering process. Polyethylene, polypropylene, polyamide 6, polyoxymethylene as well as polybutylene terephthalate were analyzed. Within the study problems of qualifying new materials are discussed using some examples. Furthermore, the processing conditions as well as mechanical properties of a new polypropylene compound are shown considering also different laser sintering machines.

  6. Terminal-level relaxation in ND-doped laser materials

    SciTech Connect

    Bibeau, C.; Payne, S.A.

    1996-06-01

    During the energy extraction of a 1-{mu}m pulse in a Nd-doped laser material, the Nd-ion population is transferred from the metastable {sup 4}F{sub 3/2} level into the terminal {sup 4}I{sub 11/2} level. The terminal-level lifetime, {tau}{sub 11/2}, is defined in this case as the time it takes the Nd-ion population to decay from the {sup 4}I{sub 11/2} level into the {sup 4}I{sub 9/2} ground state. Several experimental and theoretical approaches over the last three decades have been made to measure the terminal-level lifetime. However, an agreement in the results among the different approaches for a large sampling of laser materials has never been demonstrated. This article presents three independent methods (pump-probe, emission, and energy extraction) for measuring the terminal-level lifetime in Nd:phosphate glass LG-750. The authors find remarkable agreement among the data and determine the {tau}{sub 11/2} lifetime to be 253{+-}50 ps. They extend their studies to show that the results of the pump-probe and emission methods agree to within a factor of two for additional Nd-doped glases and crystals investigated, thus offering validation for the emission method, which is a simpler, indirect approach.

  7. Present status and future prospects of IFE and high power laser research in Asia

    NASA Astrophysics Data System (ADS)

    Mima, Kunioki

    2004-12-01

    The present status and future prospects of IFE research and high power laser applications in Asia are reviewed. At ILE, Osaka University, the Gekko XII and the Peta Watt laser system have been operated to investigate implosion hydrodynamics, fast ignition and relativistic laser plasma interactions. In particular, fast ignition experiments with cone shell targets have been carried out as joint UK-Japan and US-Japan collaboration programmes. In the experiments, imploded high density plasmas are heated by a 500 J level petawatt laser pulse. The thermal neutron yield is found to increase by three orders of magnitude by petawatt laser injection to the cone shell target. Laser plasma physics related to laser fusion and other applications has been studied at many institutes in Asia. Areas of research include Rayleigh-Taylor instability experiments, application of extreme ultraviolet radiation sources for lithography, laser particle acceleration, and x-ray lasers, to name a few.

  8. Composite multiple wavelength laser material and multiple wavelength laser for use therewith

    NASA Technical Reports Server (NTRS)

    Jani, Mahendra G. (Inventor)

    1997-01-01

    A composite multiple wavelength laser material is provided and is typically constructed with a common axis of construction in the form of a rod of uniform cross-section. The rod comprises a plurality of segments of laser material bonded, e.g., diffusion bonded, to one another along the common axis. Each segment lases at a unique wavelength when excited to produce a laser emission. The segments can be made from a birefringent material doped with laser active ions. If the same birefringent host material is used for all segments, ground-state absorption losses can be reduced by terminating either end of the rod with end segments made from undoped pieces of the birefringent material.

  9. Picosecond and femtosecond lasers for industrial material processing

    NASA Astrophysics Data System (ADS)

    Mayerhofer, R.; Serbin, J.; Deeg, F. W.

    2016-03-01

    Cold laser materials processing using ultra short pulsed lasers has become one of the most promising new technologies for high-precision cutting, ablation, drilling and marking of almost all types of material, without causing unwanted thermal damage to the part. These characteristics have opened up new application areas and materials for laser processing, allowing previously impossible features to be created and also reducing the amount of post-processing required to an absolute minimum, saving time and cost. However, short pulse widths are only one part of thee story for industrial manufacturing processes which focus on total costs and maximum productivity and production yield. Like every other production tool, ultra-short pulse lasers have too provide high quality results with maximum reliability. Robustness and global on-site support are vital factors, as well ass easy system integration.

  10. Ablative Laser Propulsion Using Multi-Layered Material Systems

    NASA Technical Reports Server (NTRS)

    Nehls, Mary; Edwards, David; Gray, Perry; Schneider, T.

    2002-01-01

    Experimental investigations are ongoing to study the force imparted to materials when subjected to laser ablation. When a laser pulse of sufficient energy density impacts a material, a small amount of the material is ablated. A torsion balance is used to measure the momentum produced by the ablation process. The balance consists of a thin metal wire with a rotating pendulum suspended in the middle. The wire is fixed at both ends. Recently, multi-layered material systems were investigated. These multi-layered materials were composed of a transparent front surface and opaque sub surface. The laser pulse penetrates the transparent outer surface with minimum photon loss and vaporizes the underlying opaque layer.

  11. Laser induced damage in optical materials: 7th ASTM symposium.

    PubMed

    Glass, A J; Guenther, A H

    1976-06-01

    The Seventh ERDA-ASTM-ONR-NBS Symposium on Laser Induced Damage in Optical Materials was held at the National Bureau of Standards in Boulder, Colorado, on 29-31 July 1975. These Symposia are held as part of the activities in ASTM Subcommittee II on Lasers and Laser Materials, which is charged with the responsibilities of formulating standards and test procedures for laser materials, components, and devices. The Chairman of Subcommittee II is Haynes Lee, of Owens-Illinois, Inc. Co-chairmen for the Damage Symposia are Arthur Guenther of the Air Force Weapons Laboratory and Alexander J. Glass of Law-rence Livermore Laboratory. Over 150 attendees at the Symposium heard forty-five papers on topics relating fabrication procedures to laser induced damage in optical materials; on metal mirrors; in ir window materials; the multipulse, wavelength, and pulse length dependence of damage thresholds; damage in dielectric films and at exposed surfaces; as well as theoretical discussions on avalanche ionization and multiphoton processes of importance at shorter wavelengths. Of particular importance were the scaling relations developed from several parametric studies relating fundamental properties (refractive index, surface roughness etc.) to the damage threshold. This year many of the extrinsic influences tending to reduce a materials damage resistance were isolated such that measures of their egregious nature could be quantified. Much still needs to be accomplished to improve processing and fabrication procedures to allow a measurable approach to a materials intrinsic strength to be demonstrated.

  12. Femtosecond lasers for machining of transparent, brittle materials: ablative vs. non-ablative femtosecond laser processing

    NASA Astrophysics Data System (ADS)

    Hendricks, F.; Matylitsky, V. V.

    2016-03-01

    This paper focuses on precision machining of transparent materials by means of ablative and non-ablative femtosecond laser processing. Ablation technology will be compared with a newly developed patent pending non-ablative femtosecond process, ClearShapeTM, using the Spectra-Physics Spirit industrial femtosecond laser.

  13. The determination of energy transfer rates in the Ho:Tm:Cr:YAG laser material

    NASA Technical Reports Server (NTRS)

    Koker, Edmond B.

    1988-01-01

    Energy transfer processes occurring between atomic, ionic, or molecular systems are very widespread in nature. The applications of such processes range form radiation physics and chemistry to biology. In the field of laser physics, energy transfer processes have been used to extend the lasing range, increase the output efficiency, and influence the spectral and temporal characteristics of the output pulses of energy transfer dye lasers or solid-state laser materials. Thus in the development of solid state lasers, it is important to investigate the basic energy transfer (ET) mechanisms and processes in order to gain detailed knowledge so that successful technical utilization can be achieved. The aim of the present research is to measure the ET rate from a given manifold associated with the chromium sensitizer atom to a given manifold in the holmium activator atom via the thulium transfer atom, in the Ho:Cr:YAG laser material.

  14. Air emissions from laser drilling of printed wiring board materials. Report for May 1995--July 1997

    SciTech Connect

    Darvin, C.H.; Kershner, C.J.

    1999-05-01

    The paper gives results of a study to characterize gases generated during laser drilling of printed wiring board (PWB) material and identifies the pollutants and generation rates found during the drilling process. The electronics packaging industry has traditionally relied on mechanical drilling systems to prepare holes in PWB material. Recently, however, a potentially new and innovative application for laser technology was developed for drilling PWB holes. This application of lasers has the potential to significantly reduce the time and cost of producing PWBs. The process is also predicted to reduce the volume of solid waste product generated during PWB manufacture. The continuing question presented on the use of laser drilling is its potential for producing air pollution which may be generated from thermal decomposition at the laser drilling site.

  15. Laser-shock damage of iron-based materials

    NASA Astrophysics Data System (ADS)

    Chu, Jinn P.; Banas, Grzegorz; Lawrence, Frederick V.; Rigsbee, James M.; Elsayed-Ali, Hani E.

    1993-05-01

    The effects of laser shock processing on the microstructure and mechanical properties of the manganese (1 percent C and 14 percent Mn) steels have been low carbon (0.04 wt. percent C) and Hadfield studied. Laser shock processing was performed with a 1.054 micrometers wavelength Nd-phosphate laser operating in a pulse mode (600 ps pulse length and up to 200 J energy) with power densities above 10 to the 11th power W/cm2. Shock waves were generated by volume expansion of the plasma formed when the material was laser irradiated. Maximum shock wave intensities were obtained using an energy-absorbing black paint coating without a plasma-confining overlay. Maximum modification of compressive residual stresses were achieved when laser shock processing induced deformation occurred without melting. Mechanical properties were improved through modifying the microstructure by laser shock processing. High density arrays of dislocations (greater than 10 to the 11th power/cm2) were generated in low carbon steel by high strain-rate deformation of laser shock processing, resulting in surface hardness increases of 30 to 80 percent. In austenitic Hadfield steel, laser shock processing caused extensive formation of Epsilon-hcp martensite (35 vol. percent), producing increases of 50 to 130 percent in surface hardness. The laser shock processing strengthening effect in Hadfield steel was attributed to the combined effects of the partial dislocation/stacking fault arrays and the grain refinement due to presence of the Epsilon-hcp martensite.

  16. Upstream Material Accumulation and Meandering on Present Day Gully Evolution

    NASA Astrophysics Data System (ADS)

    Pasquon, K.; Gargani, J.; Massé, M.; Conway, S. J.; Vincendon, M.; Séjourné, A.

    2016-09-01

    Here we show the present day evolution of a martian gully during the last 4 MY: (1) non-seasonal material accumulation in the alcove, (2) seasonal evolution of meanders, (3) extension of the channel, (4) significant modifications of the debris apron.

  17. Short-pulse laser beam interactions with biocompatible polymer materials and tissue

    NASA Astrophysics Data System (ADS)

    Serafetinides, Alexander A.

    1996-12-01

    Pulsed laser beams, of very short duration, appear to be very promising tools for polymer surface processing. Recently we have studied the interaction of picosecond and femtosecond laser radiation in the visible region of the spectrum with synthetic polymer films and we have compared these studies with our similar studies with nanosecond duration laser radiation. Biocompatible polymers have been extensively used for sutures, vascular grafts or bone and other hard tissue replacements. The use of surgical lasers for intervention on biocompatible material - tissue interfaces has attracted a great deal of interest, as both the high intensity, short pulse duration lasers and the prosthetic biomaterials are in increasing use. Our recent ablation studies, using ultrashort laser pulses, of biocompatible materials, are described in this article. Lasers were introduced in medical research in the early sixties but the laser beam ability to remove efficiently and safely soft or hard tissue, the lateral thermal damage and the final surface characteristics are still under investigation. In the past few years, by virtue of their water or water and hydroxyapatite content respectively, exhibit strong absorption restricting residual thermal damage to a relatively small zone. Recently we have investigated the interaction of short pulse laser radiation of picosecond and femtosecond duration with soft and hard tissue, as this unexplored field is expected to be a potential alternative in powerful laser processing of biomedical structures. The experimental results obtained, including ablation rates, ablation wavelength dependence, pulse duration dependence, fluence dependence, etc. are presented. These results are discussed according to simple theoretical models of laser energy absorption and the possible mechanisms of ultrashort pulse laser ablation, which in some cases involves multiphoton photodissociation processes. Finally, the design characteristics of the lasers employed in our

  18. Laser diagnostics of materials and chemistry

    SciTech Connect

    Hartford, A. Jr.

    1984-01-01

    Several examples are given of the ability of laser-based diagnostic techniques to make noninvasive measurements in hostile environments. Using coherent anti-Stokes Raman scattering both majority and minority species concentrations, as well as temperature, have been measured in the hot, high-pressure, particle-laden stream of a coal gasifier. In addition, numerous toxic and corrosive elements in the gasifier stream have been identified, but not yet quantified. In addition to providing the capability for making analytical determinations, laser techniques have been extensively employed to measure the rates of elementary chemical reactions. Recently, the temperature regime over which such meaurements are possible has been expanded. Although much of the laser diagnostic activity to date has involved investigations of the gas phase, significant information concerning heterogeneous phenomena can still be inferred. For instance, gas-solid reactions can manifest themselves as changes in vapor phase composition. Furthermore, in the future we expect expanded studies involving reactions of refractory metals (both atoms and clusters) and additional investigations of processes occurring at interfaces and on surfaces.

  19. Space-selective laser joining of dissimilar transparent materials using femtosecond laser pulses

    SciTech Connect

    Watanabe, Wataru; Onda, Satoshi; Tamaki, Takayuki; Itoh, Kazuyoshi; Nishii, Junji

    2006-07-10

    We report on the joining of dissimilar transparent materials based on localized melting and resolidification of the materials only around the focal volume due to nonlinear absorption of focused femtosecond laser pulses. We demonstrate the joining of borosilicate glass and fused silica, whose coefficients of thermal expansion are different. The joint strength and the transmittance through joint volume were investigated by varying the translation velocity of the sample and the pulse energy of the irradiated laser pulses.

  20. Durability of Polymeric Encapsulation Materials for Concentrating Photovoltaic Systems (Presentation)

    SciTech Connect

    Miller, D. C.; Muller, M.; Kempe, M. D.; Araki, K.; Kennedy, C. E.; Kurtz, S. R.

    2011-04-01

    Presented at the 7th International Conference on Concentrating Photovoltaic Systems (CPV-7), 4-6 April 2011, Las Vegas, Nevada. Many concentrating photovoltaic (CPV) systems use a polymeric encapsulant to couple an optical component and/or coverglass to the cell. In that location, the encapsulation improves the transmission of concentrated optical flux through interfaces(s) while protecting the cell from the environment. The durability of encapsulation materials, however, is not well established relative to the desired service life of 30 years. Therefore, we have initiated a screen test to identify the field-induced failure modes for a variety of popular PV encapsulation materials.

  1. Material Property Measurement in Hostile Environments using Laser Acoustics

    SciTech Connect

    Ken L. Telschow

    2004-08-01

    Acoustic methods are well known and have been used to measure various intrinsic material properties, such as, elastic coefficients, density, crystal axis orientation, microstructural texture, and residual stress. Extrinsic properties, such as, dimensions, motion variables or temperature are also readily determined from acoustic methods. Laser acoustics, employing optical generation and detection of elastic waves, has a unique advantage over other acoustic methods—it is noncontacting, uses the sample surface itself for transduction, requires no couplant or invasive sample surface preparation and can be utilized in any hostile environment allowing optical access to the sample surface. In addition, optical generation and detection probe beams can be focused to the micron scale and/or shaped to alter the transduction process with a degree of control not possible using contact transduction methods. Laser methods are amenable to both continuous wave and pulse-echo measurements and have been used from Hz to 100’s of GHz (time scales from sec to psec) and with amplitudes sufficient to fracture materials. This paper shall review recent applications of laser acoustic methods to determining material properties in hostile environments that preclude the use of contacting transduction techniques. Example environments include high temperature (>1000C) sintering and molten metal processing, thin film deposition by plasma techniques, materials moving at high velocity during the fabrication process and nuclear high radiation regions. Recent technological advances in solid-state lasers and telecommunications have greatly aided the development and implementation of laser acoustic methods, particularly at ultra high frequencies. Consequently, laser acoustic material property measurements exhibit high precision and reproducibility today. In addition, optical techniques provide methods of imaging acoustic motion that is both quantitative and rapid. Possible future directions for

  2. Imaging laser analysis of building materials - practical examples

    SciTech Connect

    Wilsch, G.; Schaurich, D.; Wiggenhauser, H.

    2011-06-23

    The Laser induced Breakdown Spectroscopy (LIBS) is supplement and extension of standard chemical methods and SEM- or Micro-RFA-applications for the evaluation of building materials. As a laboratory method LIBS is used to gain color coded images representing composition, distribution of characteristic ions and/or ingress characteristic of damaging substances. To create a depth profile of element concentration a core has to be taken and split along the core axis. LIBS was proven to be able to detect all important elements in concrete, e. g. Chlorine, Sodium or Sulfur, which are responsible for certain degradation mechanisms and also light elements like lithium or hydrogen. Practical examples are given and a mobile system for on-site measurements is presented.

  3. Final Report: Laser-Material Interactions Relevant to Analytic Spectroscopy of Wide Band Gap Materials

    SciTech Connect

    Dickinson, J. T.

    2014-04-05

    We summarize our studies aimed at developing an understanding of the underlying physics and chemistry in terms of laser materials interactions relevant to laser-based sampling and chemical analysis of wide bandgap materials. This work focused on the determination of mechanisms for the emission of electrons, ions, atoms, and molecules from laser irradiation of surfaces. We determined the important role of defects on these emissions, the thermal, chemical, and physical interactions responsible for matrix effects and mass-dependent transport/detection. This work supported development of new techniques and technology for the determination of trace elements contained such as nuclear waste materials.

  4. The materiality of mathematics: presenting mathematics at the blackboard.

    PubMed

    Greiffenhagen, Christian

    2014-09-01

    Sociology has been accused of neglecting the importance of material things in human life and the material aspects of social practices. Efforts to correct this have recently been made, with a growing concern to demonstrate the materiality of social organization, not least through attention to objects and the body. As a result, there have been a plethora of studies reporting the social construction and effects of a variety of material objects as well as studies that have explored the material dimensions of a diversity of practices. In different ways these studies have questioned the Cartesian dualism of a strict separation of 'mind' and 'body'. However, it could be argued that the idea of the mind as immaterial has not been entirely banished and lingers when it comes to discussing abstract thinking and reasoning. The aim of this article is to extend the material turn to abstract thought, using mathematics as a paradigmatic example. This paper explores how writing mathematics (on paper, blackboards, or even in the air) is indispensable for doing and thinking mathematics. The paper is based on video recordings of lectures in formal logic and investigates how mathematics is presented at the blackboard. The paper discusses the iconic character of blackboards in mathematics and describes in detail a number of inscription practices of presenting mathematics at the blackboard (such as the use of lines and boxes, the designation of particular regions for specific mathematical purposes, as well as creating an 'architecture' visualizing the overall structure of the proof). The paper argues that doing mathematics really is 'thinking with eyes and hands' (Latour 1986). Thinking in mathematics is inextricably interwoven with writing mathematics. PMID:24620862

  5. The materiality of mathematics: presenting mathematics at the blackboard.

    PubMed

    Greiffenhagen, Christian

    2014-09-01

    Sociology has been accused of neglecting the importance of material things in human life and the material aspects of social practices. Efforts to correct this have recently been made, with a growing concern to demonstrate the materiality of social organization, not least through attention to objects and the body. As a result, there have been a plethora of studies reporting the social construction and effects of a variety of material objects as well as studies that have explored the material dimensions of a diversity of practices. In different ways these studies have questioned the Cartesian dualism of a strict separation of 'mind' and 'body'. However, it could be argued that the idea of the mind as immaterial has not been entirely banished and lingers when it comes to discussing abstract thinking and reasoning. The aim of this article is to extend the material turn to abstract thought, using mathematics as a paradigmatic example. This paper explores how writing mathematics (on paper, blackboards, or even in the air) is indispensable for doing and thinking mathematics. The paper is based on video recordings of lectures in formal logic and investigates how mathematics is presented at the blackboard. The paper discusses the iconic character of blackboards in mathematics and describes in detail a number of inscription practices of presenting mathematics at the blackboard (such as the use of lines and boxes, the designation of particular regions for specific mathematical purposes, as well as creating an 'architecture' visualizing the overall structure of the proof). The paper argues that doing mathematics really is 'thinking with eyes and hands' (Latour 1986). Thinking in mathematics is inextricably interwoven with writing mathematics.

  6. Methods and apparatus for removal and control of material in laser drilling of a borehole

    DOEpatents

    Rinzler, Charles C; Zediker, Mark S; Faircloth, Brian O; Moxley, Joel F

    2014-01-28

    The removal of material from the path of a high power laser beam during down hole laser operations including drilling of a borehole and removal of displaced laser effected borehole material from the borehole during laser operations. In particular, paths, dynamics and parameters of fluid flows for use in conjunction with a laser bottom hole assembly.

  7. Novel materials for stable perovskite solar cells (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Abate, Antonio

    2015-09-01

    Organic-inorganic perovskites are quickly overrunning research activities in new materials for cost-effective and high-efficiency photovoltaic technologies. Since the first demonstration from Kojima and co-workers in 2009, several perovskite-based solar cells have been reported and certified with rapidly improving power conversion efficiency. Recent reports demonstrate that perovskites can compete with the most efficient inorganic materials, while they still allow processing from solution as potential advantage to deliver a cost-effective solar technology. Compare to the impressive progress in power conversion efficiency, stability studies are rather poor and often controversial. An intrinsic complication comes from the fact that the stability of perovskite solar cells is strongly affected by any small difference in the device architecture, preparation procedure, materials composition and testing procedure. In the present talk we will focus on the stability of perovskite solar cells in working condition. We will discuss a measuring protocol to extract reliable and reproducible ageing data. We will present new materials and preparation procedures which improve the device lifetime without giving up on high power conversion efficiency.

  8. Laser induced damage in optical materials: ninth ASTM symposium.

    PubMed

    Glass, A J; Guenther, A H

    1978-08-01

    The Ninth Annual Symposium on Optical Materials for High Power Lasers (Boulder Damage Symposium) was held at the National Bureau of Standards in Boulder, Colorado, 4-6 October 1977. The symposium was under the auspices of ASTM Committee F-1, Subcommittee on Laser Standards, with the joint sponsorship of NBS, the Defense Advanced Research Project Agency, the Department of Energy (formerly ERDA), and the Office of Naval Research. About 185 scientists attended, including representatives of the United Kingdom, France, Canada, Australia, Union of South Africa, and the Soviet Union. The Symposium was divided into sessions concerning Laser Windows and Materials, Mirrors and Surfaces, Thin Films, Laser Glass and Glass Lasers, and Fundamental Mechanisms. As in previous years, the emphasis of the papers was directed toward new frontiers and new developments. Particular emphasis was given to materials for use from 10.6 microm to the uv region. Highlights included surface characterization, thin film-substrate boundaries, and advances in fundamental laser-matter threshold interactions and mechanisms. The scaling of damage thresholds with pulse duration, focal area, and wavelength were also discussed. Alexander J. Glass of Lawrence Livermore Laboratory and Arthur H. Guenther of the Air Force Weapons Laboratory were co-chairpersons. The Tenth Annual Symposium is scheduled for 12-14 September 1978 at the National Bureau of Standards, Boulder, Colorado.

  9. On-machine laser triangulation sensor for precise surface displacement measurement of various material types

    NASA Astrophysics Data System (ADS)

    Žbontar, Klemen; Podobnik, Boštjan; Povše, Franc; Mihelj, Matjaž

    2013-09-01

    The paper presents a custom-designed laser triangulation based metrology system, which enables high precision surface displacement measurement of various material types with a single sensor configuration. Laser structuring applications require material surface alignment relative to the laser focus position where fabrication conditions are optimal. The measurement system utilizes a high-quality UV wavelength laser beam (primarily used for structuring purposes) with automatic control of its intensity. The laser source operates in a continuous wave (CW) mode during the measurement process, whereas the UV wavelength enables measurement of transparent materials. Robust displacement measurement of various material types was solved by introducing a new approach of structured light projection and its centroid detection. A high resolution 2D galvanometric scanning system is used for dynamic symmetrical pattern projection, which is proven to reduce the effects of material surface related errors and speckle noise. Furthermore, a "double curve fitting" (DCF) centroid detection algorithm, where Gaussian curves are fitted to radial cross sections of the acquired pattern, and an ellipse is fitted to their peak positions, was introduced. The method includes subsurface scattering compensation, which proves crucial for translucent material measurement, where incident light penetrates into the material surface and causes uneven light intensity distribution of the acquired pattern. Experimental results have shown that the metrology system is robust to laser intensity variation and material type, with measurement bias lower than 50 μm and standard deviation lower than +/-6.3 μm for all materials. The developed probe has been integrated into commercial LPKF laser structuring systems.

  10. Mechanisms affecting kinetic energies of laser-ablated materials

    SciTech Connect

    Chen, K.R. |; Leboeuf, J.N.; Wood, R.F.; Geohegan, D.B.; Donato, J.M.; Liu, C.L.; Puretzky, A.A.

    1995-12-31

    Laser materials processing techniques are expected to have a dramatic impact on materials science and engineering in the near future and beyond. One of the main laser materials processing techniques is Pulsed Laser Deposition (PLD) for thin film growth. While experimentalists search for optimal approaches for thin film growth with pulsed laser deposition (PLD), a systematic effort in theory and modeling of various processes during PLD is needed. The quality of film deposited depends critically on the range and profile of the kinetic energy and density of the ablated plume. While it is to the advantage of pulsed laser deposition to have high kinetic energy, plumes that are too energetic causes film damage. A dynamic source effect was found to accelerate the plume expansion velocity much higher than that from a conventional free expansion model. A self-similar theory and a hydrodynamic model are developed to study this effect, which may help to explain experimentally observed high front expansion velocity. Background gas can also affect the kinetic energies. High background gas may cause the ablated materials to go backward. Experimentally observed plume splitting is also discussed.

  11. Laser applications present and future: Prospects for significant occupational safety and health impact

    NASA Astrophysics Data System (ADS)

    Smith, J. P.

    1982-06-01

    Applications of lasers are growing in a number of areas; some applications are relatively widespread with developed industrial laser processes while others are considered purely research and development applications with little industrial use at the present time. In this brief writeup an attempt will be made to examine present and future areas of laser use and assess how they may impact on occupational safety and health in either a positive or negative way.

  12. Neural network modeling of the laser material-removal process

    NASA Astrophysics Data System (ADS)

    Yousef, Basem F.; Knopf, George K.; Bordatchev, Evgueni V.; Nikumb, Suwas K.

    2001-12-01

    Industrial lasers are used extensively in modern manufacturing for a variety of applications because these tools provide a highly focused energy source that can be easily transmitted and manipulated for micro-machining. The quantity of material removed and the roughness of the finished surface are a function of the crater geometry formed by a laser pulse with specific energy (power). Laser micro-machining is, however, a complex nonlinear process with numerous stochastic parameters related to the laser apparatus and the material specimen. Consequently, the operator must manually set the process control parameters by trial and error. This paper describes how an artificial neural network can be used to create a nonlinear model of the laser material-removal process in order to automate micro-machining tasks. The multi-layered neural network predicts the pulse energy needed to create a crater of specific depth and average diameter. Laser pulses of different energy levels are impinged on the surface of the test material in order to investigate the effect of pulse energy on the resulting crater geometry and volume of material removed. Experimentally acquired data from several sample materials are used to train and test the network's performance. The key system inputs for the modeler are mean depth of crater and mean diameter of crater, and the system outputs are pulse energy, variance of depth and variance of diameter. The preliminary study using the experimentally acquired data demonstrates that the proposed network can simulate the behavior of the physical process to a high degree of accuracy. Future work involves investigating the effect of different input parameters on the output behavior of the process in hopes that the process performance, and the final product quality, can be improved.

  13. Modeling of plume dynamics in laser ablation processes for thin film deposition of materials

    SciTech Connect

    Leboeuf, J.N.; Chen, K.R.; Donato, J.M.; Geohegan, D.B.; Liu, C.L.; Puretzky, A.A.; Wood, R.F.

    1995-12-31

    The transport dynamics of laser-ablated neutral/plasma plumes are of significant interest for film growth by pulsed-laser deposition of materials since the magnitude and kinetic energy of the species arriving at the deposition substrate are key processing parameters. Dynamical calculations of plume propagation in vacuum and in background gas have been performed using particle-in-cell hydrodynamics, continuum gas dynamics, and scattering models. Results from these calculations are presented and compared with experimental observations.

  14. Fabrication of a reinforced polymer microstructure using femtosecond laser material processing

    NASA Astrophysics Data System (ADS)

    Alubaidy, M.; Venkatakrishnan, K.; Tan, B.

    2010-05-01

    This paper presents a new method for the formation of microfeatures with reinforced polymer using femtosecond laser material processing. The femtosecond laser was used for the generation of a three-dimensional interweaved nanofiber and the construction of microfeatures, such as microchannels and voxels, through two-photon polymerization of a nanofiber-dispersed polymer resin. This new method has the potential of direct fabrication of reinforced micro/nanostructures.

  15. Analysis of fabric materials cut using ultraviolet laser ablation

    NASA Astrophysics Data System (ADS)

    Tsai, Hsin-Yi; Yang, Chih-Chung; Hsiao, Wen-Tse; Huang, Kuo-Cheng; Andrew Yeh, J.

    2016-04-01

    Laser ablation technology has widely been applied in the clothing industry in recent years. However, the laser mechanism would affect the quality of fabric contours and its components. Hence, this study examined carbonization and oxidation conditions and contour variation in nonwoven, cotton, and composite leather fabrics cut by using an ultraviolet laser at a wavelength of 355 nm. Processing parameters such as laser power, pulse frequency, scanning speed, and number of pulses per spot were adjusted to investigate component variation of the materials and to determine suitable cutting parameters for the fabrics. The experimental results showed that the weights of the component changed substantially by pulse frequency but slightly by laser power, so pulse frequency of 100 kHz and laser power of 14 W were the approximate parameters for three fabrics for the smaller carbonization and a sufficient energy for rapidly cutting, which the pulse duration of laser system was fixed at 300 μs and laser irradiance was 0.98 J/mm2 simultaneously. In addition, the etiolate phenomenon of nonwoven was reduced, and the component weight of cotton and composite leather was closed to the value of knife-cut fabric as the scanning speed increased. The approximate scanning speed for nonwoven and composite leather was 200 mm/s, and one for cotton was 150 mm/s, respectively. The sharper and firmer edge is obtained by laser ablation mechanism in comparison with traditional knife cutting. Experimental results can serve as the reference for laser cutting in the clothing industry, for rapidly providing smoother patterns with lower carbonization and oxidation edge in the fashion industry.

  16. Durability of Polymeric Encapsulation Materials for Concentrating Photovoltaic Systems (Presentation)

    SciTech Connect

    Miller, D. C.; Muller, M.; Kempe, M. D.; Araki, K.; Kennedy, C. E.; Kurtz, S. R.

    2012-03-01

    Many concentrating photovoltaic (CPV) systems use a polymeric encapsulant to couple and optical component and/or coverglass to the cell. In that location, the encapsulation improves the transmission of concentrated optical flux through interface(s), while protecting the cell from the environment. The durability of encapsulation materials, however, is not well established relative to the desired service life of 30 years. Therefore, we have initiated a screen test to identify the field-induced failure modes for a variety of popular PV encapsulation materials. An existing CPV module (with no PV cells present) was modified to accommodate encapsulation specimens. The module (where nominal concentration of solar flux is 500x for the domed-Fresnel design) has been mounted on a tracker in Golden, CO (elevation 1.79 km). Initial results are reported here for 18 months cumulative exposure, including the hottest and coldest months of the past year. Characteristics observed at intervals during that time include: visual appearance, direct and hemispherical transmittance, and mass. Degradation may be assessed from subsequent analysis (including yellowness index and cut-on frequency) relative to the ambient conditions present during field exposure. The fluorescence signature observed of all the silicone specimens is examined here, including possible factors of causation -- the platinum catalyst used in the addition cured materials as well as the primer used to promote adhesion to the quartz substrate and superstrate.

  17. Advances in optical materials for large aperture lasers

    SciTech Connect

    Stokowski, S.E.; Lowdermilk, W.H.; Marchi, F.T.; Swain, J.E.; Wallerstein, E.P.; Wirtenson, G.R.

    1981-12-15

    Lawrence Livermore National Laboratory (LLNL) is using large aperture Nd: glass lasers to investigate the feasibility of inertial confinement fusion. In our experiments high power laser light is focussed onto a small (100 to 500 micron) target containing a deuterium-tritium fuel mixture. During the short (1 to 5 ns) laser pulse the fuel is compressed and heated, resulting in fusion reactions. The generation and control of the powerful laser pulses for these experiments is a challenging scientific and engineering task, which requires the development of new optical materials, fabrication techniques, and coatings. LLNL with the considerable cooperation and support from the optical industry, where most of the research and development and almost all the manufacturing is done, has successfully applied several new developments in these areas.

  18. Present Status and Future Prospects of Laser Fusion and Related High Energy Density Plasma Research

    NASA Astrophysics Data System (ADS)

    Mima, Kunioki

    2004-12-01

    The present status and future prospects of the laser fusion research and related laser plasma physics are reviewed. In laser fusion research, giant lasers for ignition and burn by imploding DT fuel pellets are under construction at LLNL (Lawrence Livermore National Laboratory) and CEA, France. In Japan , the Gekko XII and the Peta Watt laser system have been operated to investigate the implosion hydrodynamics, fast ignition, and the relativistic laser plasma interactions and a new project; FIREX( Fast Ignition Realization Experiment) had started toward the ignition and burn at the Institute of laser Engineering of Osaka University. Recently, heating experiments with cone shell target have been carried out. The thermal neutron yield is found to increase by three orders of magnitude by the peta watt laser injection to the cone shell target. The FIREX-I is planned according to this experimental results, where multi 10kJ peta watt laser is used to heat compressed DT fuel to the ignition temperature. The FIREX-II will follow for demonstrating ignition and burn, in which the implosion laser and heating laser are up-graded.

  19. Study on laser welding of stainless steel/copper dissimilar materials

    NASA Astrophysics Data System (ADS)

    Besnea, D.; Dontu, O.; Avram, M.; Spânu, A.; Rizescu, C.; Pascu, T.

    2016-08-01

    In this paper stainless steel/copper laser welding was investigated by controlling the processing parameters like welding speed and laser power. Welding the dissimilar materials of stainless steel and copper presents a series of problems. Differences in the physical properties of the two metals, including the melting point, thermal conductivity and thermal dilatation are the main reasons for obtaining an inappropriate laser welding bead. Particularly, the laser welding process of copper is complex because of the very high reflectivity of cooper and in almost situations it requires a specific surface pre-treatment. The main objective of the study conducted in this work was to laser weld a structure used in pressure measuring and control equipments. In order to satisfy the conditions imposed by the sensor manufacturer, the difficulty of obtaining flawless joints was represented by the very small dimensions of the parts to be welded especially of the elastic spiral thickness made of steel.

  20. A novel laser-based method for controlled crystallization in dental prosthesis materials

    NASA Astrophysics Data System (ADS)

    Cam, Peter; Neuenschwander, Beat; Schwaller, Patrick; Köhli, Benjamin; Lüscher, Beat; Senn, Florian; Kounga, Alain; Appert, Christoph

    2015-02-01

    Glass-ceramic materials are increasingly becoming the material of choice in the field of dental prosthetics, as they can feature both high strength and very good aesthetics. It is believed that their color, microstructure and mechanical properties can be tuned such as to achieve an optimal lifelike performance. In order to reach that ultimate perfection a controlled arrangement of amorphous and crystalline phases in the material is required. A phase transformation from amorphous to crystalline is achieved by a heat treatment at defined temperature levels. The traditional approach is to perform the heat treatment in a furnace. This, however, only allows a homogeneous degree of crystallization over the whole volume of the parent glass material. Here a novel approach using a local heat treatment by laser irradiation is presented. To investigate the potential of this approach the crystallization process of SiO2-Li2O-Al2O3-based glass has been studied with laser systems (pulsed and continuous wave) operating at different wavelengths. Our results show the feasibility of gradual and partial crystallization of the base material using continuous laser irradiation. A dental prosthesis machined from an amorphous glassy state can be effectively treated with laser irradiation and crystallized within a confined region of a few millimeters starting from the body surface. Very good aesthetics have been achieved. Preliminary investigation with pulsed nanosecond lasers of a few hundreds nanoseconds pulse width has enabled more refinement of crystallization and possibility to place start of phase change within the material bulk.

  1. Femtosecond laser processing of photovoltaic and transparent materials

    NASA Astrophysics Data System (ADS)

    Ahn, Sanghoon

    The photovoltaic semiconducting and transparent dielectric materials are of high interest in current industry. Femtosecond laser processing can be an effective technique to fabricate such materials since non-linear photochemical mechanisms predominantly occur. In this series of studies, femtosecond (fs) laser processing techniques that include laser drilling on Si wafer, laser scribing on CIGS thin film, laser ablation on Lithium Niobate (LN) crystal, and fabrication of 3D structures in fused silica were studied. The fs laser drilling on Si wafer was performed to fabricate via holes for wrap-through PV devices. For reduction of the number of shots in fs laser drilling process, self-action of laser light in the air was initiated. To understand physical phenomena during laser drilling, scanning electron microscopy (SEM), emission, and shadowgraph images were studied. The result indicated the presence of two mechanisms that include fabrication by self-guided beam and wall-guided beam. Based on our study, we could fabricate ~16 micrometer circular-shaped via holes with ~200 laser pulses on 160-170 micrometer thick c- and mc-Si wafer. For the fs laser scribing on ink jet printed CIGS thin film solar cell, the effect of various parameters that include pulse accumulation, wavelength, pulse energy, and overlapping were elucidated. In our processing regime, the effect of wavelength could be diminished due to compensation between beam size, pulse accumulation, energy fluence, and the absorption coefficient. On the other hand, for high PRF fs laser processing, pulse accumulation effect cannot be ignored, while it can be negligible in low PRF fs laser processing. The result indicated the presence of a critical energy fluence for initiating delamination of CIGS layer. To avoid delamination and fabricate fine isolation lines, the overlapping method can be applied. With this method, ~1 micrometer width isolation lines were fabricated. The fs laser ablation on LN wafer was studied

  2. Yb:FAP and related materials, laser gain medium comprising same, and laser systems using same

    DOEpatents

    Krupke, W.F.; Payne, S.A.; Chase, L.L.; Smith, L.K.

    1994-01-18

    An ytterbium doped laser material remarkably superior to all others, including Yb:YAG, comprises ytterbium doped apatite (Yb:Ca[sub 5](PO[sub 4])[sub 3]F) or Yb:FAP, or ytterbium doped crystals that are structurally related to FAP. The new laser material is used in laser systems pumped by diode pump sources having an output near 0.905 microns or 0.98 microns, such as InGaAs and AlInGaAs, or other narrowband pump sources near 0.905 microns or 0.98 microns. The laser systems are operated in either the conventional or ground state depletion mode. 9 figures.

  3. High-Power Fiber Lasers Using Photonic Band Gap Materials

    NASA Technical Reports Server (NTRS)

    DiDomenico, Leo; Dowling, Jonathan

    2005-01-01

    High-power fiber lasers (HPFLs) would be made from photonic band gap (PBG) materials, according to the proposal. Such lasers would be scalable in the sense that a large number of fiber lasers could be arranged in an array or bundle and then operated in phase-locked condition to generate a superposition and highly directed high-power laser beam. It has been estimated that an average power level as high as 1,000 W per fiber could be achieved in such an array. Examples of potential applications for the proposed single-fiber lasers include welding and laser surgery. Additionally, the bundled fibers have applications in beaming power through free space for autonomous vehicles, laser weapons, free-space communications, and inducing photochemical reactions in large-scale industrial processes. The proposal has been inspired in part by recent improvements in the capabilities of single-mode fiber amplifiers and lasers to produce continuous high-power radiation. In particular, it has been found that the average output power of a single strand of a fiber laser can be increased by suitably changing the doping profile of active ions in its gain medium to optimize the spatial overlap of the electromagnetic field with the distribution of active ions. Such optimization minimizes pump power losses and increases the gain in the fiber laser system. The proposal would expand the basic concept of this type of optimization to incorporate exploitation of the properties (including, in some cases, nonlinearities) of PBG materials to obtain power levels and efficiencies higher than are now possible. Another element of the proposal is to enable pumping by concentrated sunlight. Somewhat more specifically, the proposal calls for exploitation of the properties of PBG materials to overcome a number of stubborn adverse phenomena that have impeded prior efforts to perfect HPFLs. The most relevant of those phenomena is amplified spontaneous emission (ASE), which causes saturation of gain and power

  4. Two-meter laser material response impulse measurements

    NASA Astrophysics Data System (ADS)

    Robertson, Karin; Cates, Michael C.

    1988-02-01

    Impulse generated by Excimer Laser Target interactions has been extensively studied at Maxwell Labs. Inc. Results are presented of impulse measurements on aluminum targets using the SDIO/MLI Two Meter Laser operating with KrF as the lasing media. The results of previous MLI impulse measurements using XeF laser media are summarized. The work presented was motivated by earlier impulse measurements also taken on the Two Meter Laser. The data showed much higher impulse to energy ratios than predicted. Additionally, work done elsewhere gave lower I/E values than those found at MLI. The initial MLI impulse studies used a Fotonic gauge as a velocity sensor. As a check on its accuracy, impulse was measured using a simple pendulum; the results agreed with the Fotonic gauge data. A careful investigation of the pendulum experimental technique followed; no problem were found. The S-Cubed ZOOS code was also examined. It is a 1 and 1/2-D code, and only accounts for impulse delivered under the Laser footprint. Additional momentum, however, is provided outside the laser spot via the plasma cloud that results from the laser target interaction.

  5. AIR EMISSIONS FROM LASER DRILLING OF PRINTED WIRING BOARD MATERIALS

    EPA Science Inventory

    The paper gives results of a study to characterize gases generated during laser drilling of printed wiring board (PWB) material and identifies the pollutants and generation rates found during the drilling process. Typically found in the missions stream were trace amounts of carbo...

  6. Analysis and studies on the threats to the composite material from laser

    NASA Astrophysics Data System (ADS)

    Xu, Wei; Yao, Weixing; Wang, Liwei; Wang, Guoliang; Xie, Fang

    2015-10-01

    It is always an attracting research field for the interaction between laser and matters. The interaction between laser and matters is used not only in the natural science, but also in practical application, for example, laser machine, laser weapon, laser ablations and so on. In this paper, we will give the model for the damage effect of the composite materials caused by the superpower laser weapons. Mechanism of the laser damage on the composite materials have been researched and modeled by the numerical analysis methods. Through the designed model, we analyzed the temperature and the stress fields of the composite material after the superpower lasers attacks with different power densities. By analyzing these modeling results, we achieved some conclusions on the threats to the composite materials from the superpower lasers. From the results, we have obtained the Irradiated threshold from the Laser. This paper will provide the theoretical foundations for the anti-laser design of the composite materials.

  7. Optimization of laser ablation and signal enhancement for nuclear material detection

    NASA Astrophysics Data System (ADS)

    LaHaye, Nicole L.

    The purpose of the study was to investigate the role of different laser parameters on laser ablation properties, specifically in terms of performance in laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Many laser parameters affect laser ablation performance, including laser wavelength and pulse duration, as presented here. It was previously thought that wavelength plays no role in ultrafast laser ablation; however, it was found that shorter wavelength yields lower detection limits and ablation threshold. Our results also demonstrate that in the laser pulse duration range of 40 fs to 1 ps, negligible differences occur in signal intensity, elemental ratios, and detection limits. U/Pb and U/Th ratios, which were examined to ensure limited fractionation, give comparable results at all pulse widths investigated. A parametric study of plasma hydrodynamics will also be presented. An elemental detection method combining laser induced breakdown spectroscopy (LIBS) and LA-ICP-MS is developed, with plasma density and temperature actively monitored to investigate how plasma conditions affect ICP-MS results. The combination of these two methods will help to mitigate the disadvantages of using each technique individually. Depth and spatial analysis of thin films was performed using femtosecond LA-ICP-MS to study the stoichiometric distribution of the films. The thin film-substrate interface was probed, revealing intermixing between the two layers. Lastly, the persistence of uranium emission in laser-produced plasmas (LPP) was investigated under various Ar ambient environments. Plasma collisional effects and confinement play a very important role in emission intensity and persistence, yielding important results for future LIBS and laser absorption spectroscopy (LAS) research. Lastly, suggestions for future work are made, which include extension of the LIBS and LA-ICP-MS systems to other samples like oxide thin films and spatial and depth profiling of known

  8. Pulsed laser processing of electronic materials in micro/nanoscale

    NASA Astrophysics Data System (ADS)

    Hwang, David Jen

    2005-08-01

    Time-resolved pump-and-probe side-view imaging has been performed to investigate the energy coupling to the target specimen over a wide range of fluences. Plasmas generated during the laser ablation process are visualized and the decrease of the ablation efficiency in the high fluence regime (>10 J/cm2) is attributed to the strong interaction of the laser pulse with the laser-induced plasmas. The high intensity ultra-short laser pulses also trigger volumetric multi-photon absorption (MPA) processes that can be beneficial in applications such as three-dimensional bulk modification of transparent materials. Femtosecond laser pulses were used to fabricate straight and bent through-channels in the optical glass. Drilling was initiated from the rear surface to preserve consistent absorbing conditions of the laser pulse. Machining in the presence of a liquid solution assisted the debris ejection. Drilling process was further enhanced by introducing ultrasonic waves, thereby increasing the aspect ratio of drilled holes and improving the quality of the holes. In conventional lens focusing schemes, the minimum feature size is determined by the diffraction limit. Finer resolution is accomplished by combining pulsed laser radiation with Near-field Scanning Optical Microscopy (NSOM) probes. Short laser pulses are coupled to a fiber-based NSOM probes in order to ablate thin metal films. A detailed parametric study on the effects of probe aperture size, laser pulse energy, temporal width and environment gas is performed. The significance of lateral thermal diffusion is highlighted and the dependence of the ablation process on the imparted near-field distribution is revealed. As a promising application of laser ablation in nanoscale, laser induced breakdown spectroscopy (LIBS) system has been built up based on NSOM ablation configuration. NSOM-LIBS is demonstrated with nanosecond pulsed laser excitation on Cr sample. Far-field collecting scheme by top objective lens was chosen as

  9. Power plant material characterization by lasers. Final report

    SciTech Connect

    Not Available

    1993-02-01

    The EPRI Nuclear Division undertook examination of the feasibility of utilizing lasers to perform in situ operations within power plants in 1983. The Nd- Yag laser was of particular interest because flexible fiber optics cabling could be utilized for beam transport; the end effectors could be made small enough to access power plant components remotely. Beam management for welding and metal conditioning in confined spaces; the first issue examined, lead to the application for steam generator repairs that is now in common usage. This report examines the laser beam as a source of information about the material property condition; an application made feasible by advances in fiber and laser technology that were achieved beginning in 1989. This work, examines the prospects for determination of material condition properties within power plants because the laser beam can be utilized for sampling and as a source of optical, thermal, ultrasonic, spectrographic and mensuration data that may be obtained nondestructively. Both application evaluations and feasibility testing is described.

  10. Pre-ignition laser ablation of nanocomposite energetic materials

    NASA Astrophysics Data System (ADS)

    Stacy, S. C.; Massad, R. A.; Pantoya, M. L.

    2013-06-01

    Laser ignition of energetic material composites was studied for initiation with heating rates from 9.5 × 104 to 1.7 × 107 K/s. This is a unique heating rate regime for laser ignition studies because most studies employ either continuous wave CO2 lasers to provide thermal ignition or pulsed Nd:YAG lasers to provide shock ignition. In this study, aluminum (Al) and molybdenum trioxide (MoO3) nanoparticle powders were pressed into consolidated pellets and ignited using a Nd:YAG laser (1064 nm wavelength) with varied pulse energy. Results show reduced ignition delay times corresponding to laser powers at the ablation threshold for the sample. Heating rate and absorption coefficient were determined from an axisymmetric heat transfer model. The model estimates absorption coefficients from 0.1 to 0.15 for consolidated pellets of Al + MoO3 at 1064 nm wavelength. Ablation resulted from fracturing caused by a rapid increase in thermal stress and slowed ignition of the pellet.

  11. Pre-ignition laser ablation of nanocomposite energetic materials

    SciTech Connect

    Stacy, S. C.; Massad, R. A.; Pantoya, M. L.

    2013-06-07

    Laser ignition of energetic material composites was studied for initiation with heating rates from 9.5 Multiplication-Sign 10{sup 4} to 1.7 Multiplication-Sign 10{sup 7} K/s. This is a unique heating rate regime for laser ignition studies because most studies employ either continuous wave CO{sub 2} lasers to provide thermal ignition or pulsed Nd:YAG lasers to provide shock ignition. In this study, aluminum (Al) and molybdenum trioxide (MoO{sub 3}) nanoparticle powders were pressed into consolidated pellets and ignited using a Nd:YAG laser (1064 nm wavelength) with varied pulse energy. Results show reduced ignition delay times corresponding to laser powers at the ablation threshold for the sample. Heating rate and absorption coefficient were determined from an axisymmetric heat transfer model. The model estimates absorption coefficients from 0.1 to 0.15 for consolidated pellets of Al + MoO{sub 3} at 1064 nm wavelength. Ablation resulted from fracturing caused by a rapid increase in thermal stress and slowed ignition of the pellet.

  12. X-Lase CoreScriber, Picosecond Fiber Laser Tool for High-Precision Scribing and Cutting of Transparent Materials

    NASA Astrophysics Data System (ADS)

    Kivistö, S.; Amberla, T.; Konnunaho, T.; Kangastupa, J.; Sillanpää, J.

    We have developed various industrial transparent material scribing processes and a laser tool, picosecond MHz-range all- fiber laser X-Lase CoreScriber. The remarkably high peak power, exceptionally good beam quality, and integrability of the X-Lase CoreScriber combined with high achievable material processing speeds provide tempting solutions for high- precision glass processing. Here presented sapphire and Gorilla glass dicing processes are based on transparent material internal modification with short and intense high repetition rate ps-laser pulses. Increased processing speeds and cutting qualities in comparison to other conventional processing methods are presented.

  13. Laser-shocked energetic materials with metal additives: evaluation of detonation performance

    NASA Astrophysics Data System (ADS)

    Gottfried, Jennifer; Bukowski, Eric

    A focused, nanosecond-pulsed laser with sufficient energy to exceed the breakdown threshold of a material generates a laser-induced plasma with high peak temperatures, pressures, and shock velocities. Depending on the laser parameters and material properties, nanograms to micrograms of material is ablated, atomized, ionized and excited in the laser-induced plasma. The subsequent shock wave expansion into the air above the sample has been monitored using high-speed schlieren imaging in a recently developed technique, laser-induced air shock from energetic materials (LASEM). The estimated detonation velocities using LASEM agree well with published experimental values. A comparison of the measured shock velocities for various energetic materials including RDX, DNTF, and LLM-172 doped with Al or B to the detonation velocities predicted by CHEETAH for inert or active metal participation demonstrates that LASEM has potential for predicting the early time participation of metal additives in detonation events. The LASEM results show that reducing the amount of hydrogen present in B formulations increases the resulting detonation velocities

  14. Laser ablation plasmas for diagnostics of structured electronic and optical materials during or after laser processing

    NASA Astrophysics Data System (ADS)

    Russo, Richard E.; Bol'shakov, Alexander A.; Yoo, Jong H.; González, Jhanis J.

    2012-03-01

    Laser induced plasma can be used for rapid optical diagnostics of electronic, optical, electro-optical, electromechanical and other structures. Plasma monitoring and diagnostics can be realized during laser processing in real time by means of measuring optical emission that originates from the pulsed laser-material interaction. In post-process applications, e.g., quality assurance and quality control, surface raster scanning and depth profiling can be realized with high spatial resolution (~10 nm in depth and ~3 μm lateral). Commercial instruments based on laser induced breakdown spectrometry (LIBS) are available for these purposes. Since only a laser beam comes in direct contact with the sample, such diagnostics are sterile and non-disruptive, and can be performed at a distance, e.g. through a window. The technique enables rapid micro-localized chemical analysis without a need for sample preparation, dissolution or evacuation of samples, thus it is particularly beneficial in fabrication of thin films and structures, such as electronic, photovoltaic and electro-optical devices or circuits of devices. Spectrum acquisition from a single laser shot provides detection limits for metal traces of ~10 μg/g, which can be further improved by accumulating signal from multiple laser pulses. LIBS detection limit for Br in polyethylene is 90 μg/g using 50-shot spectral accumulation (halogen detection is a requirement for semiconductor package materials). Three to four orders of magnitude lower detection limits can be obtained with a femtosecond laser ablation - inductively coupled plasma mass spectrometer (LA-ICP-MS), which is also provided on commercial basis. Laser repetition rate is currently up to 20 Hz in LIBS instruments and up to 100 kHz in LA-ICP-MS.

  15. Cr.sup.4+-doped mixed alloy laser materials and lasers and methods using the materials

    NASA Technical Reports Server (NTRS)

    Alfano, Robert R. (Inventor); Petricevic, Vladimir (Inventor); Bykov, Alexey (Inventor)

    2008-01-01

    A laser medium includes a single crystal of Cr.sup.4+:Mg.sub.2-xM.sub.xSi.sub.1-yA.sub.yO.sub.4, where, where M is a bivalent ion having an ionic radius larger than Mg.sup.2+, and A is a tetravalent ion having an ionic radius larger than Si.sup.4+. In addition, either a) 0.ltoreq.x<2 and 0laser medium can be used in a laser device, such as a tunable near infrared (NIR) laser.

  16. Photorefractive Laser Ultrasound Spectroscopy for Materials Characterization

    SciTech Connect

    Telschow, K.L.; Deason, V.A.; Ricks, K.L.; Schley, R.S.

    1997-12-31

    Ultrasonic elastic wave motion is often used to measure or characterize material properties. Through the years, many optical techniques have been developed for applications requiring noncontacting ultrasonic measurement. Most of these methods have similar sensitivities and are based on time domain processing using interferometry. Wide bandwidth is typically employed to obtain real- time surface motion under transient conditions. However, some applications, such as structural analysis, are well served by measurements in the frequency domain that record the randomly or continuously excited vibrational resonant spectrum. A significant signal-to-noise ratio improvement is achieved by the reduced bandwidth of the measurement at the expense of measurement speed compared to the time domain methods. Complications often arise due to diffuse surfaces producing speckle that introduces an arbitrary phase component onto the optical wavefront to be recorded. Methods that correct for this effect are actively being investigated today.

  17. High-energy photon radiography system using laser-Compton scattering for inspection of bulk materials

    NASA Astrophysics Data System (ADS)

    Toyokawa, Hiroyuki; Ohgaki, Hideaki; Mikado, Tomohisa; Yamada, Kawakatsu

    2002-09-01

    Transmission radiography of bulk materials using continuously energy-tunable quasimonochromatic photon beams has been performed with the photons of a few tens MeV. The photon beam is generated with the laser-Compton scattering of the 300-800 MeV electrons in the electron storage ring "TERAS" with laser lights. The present radiography system is applicable to an inspection of bulk materials and to nondestructive testing of large industrial products. The effectiveness of the method has been examined using metals, ceramics, and concrete blocks. The spatial resolution of the radiography system was measured to be 650 mum using a 1 mm collimator system.

  18. Microstructural and mechanical characterization of laser deposited advanced materials

    NASA Astrophysics Data System (ADS)

    Sistla, Harihar Rakshit

    Additive manufacturing in the form of laser deposition is a unique way to manufacture near net shape metallic components from advanced materials. Rapid solidification facilitates the extension of solid solubility, compositional flexibility and decrease in micro-segregation in the melt among other advantages. The current work investigates the employment of laser deposition to fabricate the following: 1. Functionally gradient materials: This allows grading dissimilar materials compositionally to tailor specific properties of both these materials into a single component. Specific compositions of the candidate materials (SS 316, Inconel 625 and Ti64) were blended and deposited to study the brittle intermetallics reported in these systems. 2. High entropy alloys: These are multi- component alloys with equiatomic compositions of 5 or more elements. The ratio of Al to Ni was decreased to observe the transition of solid solution from a BCC to an FCC crystal structure in the AlFeCoCrNi system. 3. Structurally amorphous alloys: Zr-based metallic glasses have been reported to have high glass forming ability. These alloys have been laser deposited so as to rapidly cool them from the melt into an amorphous state. Microstructural analysis and X-ray diffraction were used to study the phase formation, and hardness was measured to estimate the mechanical properties.

  19. Laser-driven flyer plates for reactive materials research

    NASA Astrophysics Data System (ADS)

    Fujiwara, Hiroki; Brown, Kathryn; Conner, Rusty; Dlott, Dana

    2009-06-01

    We have developed a laser-driven flyer plate apparatus to study shock-induced chemistry of reactive materials (RM) containing Al nanoparticles. Reactive materials are generally composed of fuel and oxidizer particles. Under shock compression these components mix and react to liberate energy and do work. Understanding how shocked nanoparticle compositions undergo exothermic chemistry is a difficult problem in materials science, since the reactivity is a function of both chemical and materials parameters. Laser-launched flyer plates coated with a small amount of the RM are made to impact a window and their emission spectrum is studied. Achieving a good reproducible launch is a problem, and is generally limited by the quality of the laser beam profile and the flyer target. Our approach exploits recent advances in beam shaping and microfabrication. This material is based on work supported by the US Army Research Office under award number W911NF-04-1-0178 and the Air Force Office of Scientific Research under award number FA9550-06-1-0235. Kathryn Brown acknowledges support from the Stewardship Sciences Academic Alliance Program from the Carnegie-DOE Alliance Center under grant number DOE CIW 4-3253-13.

  20. Laser Transmission Welding of CFRTP Using Filler Material

    NASA Astrophysics Data System (ADS)

    Berger, Stefan; Schmidt, Michael

    In the automotive industry the increasing environmental awareness is reflected through consistent lightweight construction. Especially the use of carbon fiber reinforced thermoplastics (CFRTP) plays an increasingly important role. Accordingto the material substitution, the demand for adequate joining technologies is growing. Therefore, laser transmission welding with filler material provides a way to combine two opaque joining partners by using process specific advantages of the laser transmission welding process. After introducing the new processing variant and the used experimental setup, this paper investigates the process itselfand conditions for a stable process. The influence of the used process parameters on weld quality and process stability is characterized by tensile shear tests. The successfully performed joining of PA 6 CF 42 organic sheets using natural PA 6 as filler material underlines the potential of the described joining method for lightweight design and other industrial applications.

  1. Laser-Induced Damage Threshold and Certification Procedures for Optical Materials

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This document provides instructions for performing laser-induced-damage-threshold tests and pass-fail certification tests on optical materials used in pulsed-laser systems. The optical materials to which these procedures apply include coated and uncoated optical substrates, laser crystals, Q-switches, polarizers, and other optical components employed in pulsed-laser systems.

  2. CRC handbook of laser science and technology. Volume 5. Optical materials. Part 3. Applications, coatings, and fabrication

    SciTech Connect

    Weber, M.J.

    1987-01-01

    This book describes the uses, coatings, and fabrication of laser materials. Topics considered include: optical waveguide materials; optical storage materials; holographic recording materials; phase conjunction materials; holographic recording materials; phase conjunction materials; laser crystals; laser glasses; quantum counter materials; thin films and coatings; multilayer dielectric coatings; graded-index surfaces and films; optical materials fabrication; fabrication techniques; fabrication procedures for specific materials.

  3. Microstructuring of materials by pulsed-laser focusing and projection technique

    NASA Astrophysics Data System (ADS)

    Exner, Horst; Keiper, Bernd; Meja, Peter

    1999-07-01

    Presently, there is a going demand from the industry for microprocessing of materials. In particular, for application in the field of microsystem technology it is necessary to produce structures with dimensions down to the micrometer scale in various materials. We have been investigating the structuring of silicon, anodic bondable PYREX glass, Al2O3-ceramic and PMMA by means of laser microprocessing using an excimer laser and TEA CO2 laser. Both the mask projection technique and the focusing technique have been employed. We will show the dependence of the ablation thresholds and the ablation rates on the laser parameters and on the physical properties of the materials, i.e. absorption coefficient, melting point and thermal conductivity. During and after the laser processing of different glasses we observed the formation of cracks in the laser irradiated region and partly in the glass wafer surrounding the drilled holes. Those crack formations should be due to the developed of thermally induced mechanical stress in the glass.

  4. Analytical study of pulsed laser irradiation on some materials used for photovoltaic cells on satellites

    NASA Astrophysics Data System (ADS)

    Abd El-Hameed, Afaf M.

    2015-12-01

    The present research concerns on the study of laser-powered solar panels used for space applications. A mathematical model representing the laser effects on semiconductors has been developed. The temperature behavior and heat flow on the surface and through a slab has been studied after exposed to nano-second pulsed laser. The model is applied on two different types of common active semiconductor materials that used for photovoltaic cells fabrication as silicon (Si), and gallium arsenide (GaAs). These materials are used for receivers' manufacture for laser beamed power in space. Various values of time are estimated to clarify the heat flow through the material sample and generated under the effects of pulsed laser irradiation. These effects are theoretically studied in order to determine the performance limits of the solar cells when they are powered by laser radiation during the satellite eclipse. Moreover, the obtained results are carried out to optimize conversion efficiency of photovoltaic cells and may be helpful to give more explanation for layout of the light-electricity space systems.

  5. Study of transport of laser-driven relativistic electrons in solid materials

    NASA Astrophysics Data System (ADS)

    Leblanc, Philippe

    With the ultra intense lasers available today, it is possible to generate very hot electron beams in solid density materials. These intense laser-matter interactions result in many applications which include the generation of ultrashort secondary sources of particles and radiation such as ions, neutrons, positrons, x-rays, or even laser-driven hadron therapy. For these applications to become reality, a comprehensive understanding of laser-driven energy transport including hot electron generation through the various mechanisms of ionization, and their subsequent transport in solid density media is required. This study will focus on the characterization of electron transport effects in solid density targets using the state-of- the-art particle-in-cell code PICLS. A number of simulation results will be presented on the topics of ionization propagation in insulator glass targets, non-equilibrium ionization modeling featuring electron impact ionization, and electron beam guiding by the self-generated resistive magnetic field. An empirically derived scaling relation for the resistive magnetic in terms of the laser parameters and material properties is presented and used to derive a guiding condition. This condition may prove useful for the design of future laser-matter interaction experiments.

  6. Heat transfer model for cw laser material processing

    SciTech Connect

    Mazumder, J.; Steen, W.M.

    1980-02-01

    A three-dimensional heat transfer model for laser material processing with a moving Gaussian heat source is developed using finite difference numerical techniques. In order to develop the model, the process is physically defined as follows: A laser beam, having a defined power distribution, strikes the surface of an opaque substrate of infinite length but finite width and depth moving with a uniform velocity in the positive x direction (along the length). The incident radiation is partly reflected and partly absorbed according to the value of the reflectivity. The reflectivity is considered to be zero at any surface point where the temperature exceeds the boiling point. This is because a ''keyhole'' is considered to have formed which will act as a black body. Some of the absorbed energy is lost by reradiation and convection from both the upper and lower surfaces while the rest is conducted into the substrate. That part of the incident radiant power which falls on a keyhole is considered to pass into the keyhole losing some power by absorption and reflection from the plasma within the keyhole as described by a Beer Lambert absorption coefficient. Matrix points within the keyhole are considered as part of the solid conduction network, but operating at fictitiously high temperatures. The convective heat transfer coefficient is enhanced to allow for a concentric gas jet on the upper surface as used for shielding in welding and surface treatment, but not cutting. The system is considered to be in a quasi-steady-state condition in that the thermal profile is considered steady relative to the position of the laser beam. The advantages of this method of calculation over others are discussed together with comparisons between the model predictions and experiments in laser welding, laser arc augmented welding, laser surface treatment, and laser glazing.

  7. Evaluation of Laser Stabilization and Imaging Systems for LCLS-II - Oral Presentation

    SciTech Connect

    Barry, Matthew

    2015-08-19

    This presentation covers data collected on two commercial laser stabilization systems, Guidestar-II and MRC, and two optical imaging systems. Additionally, general information about LCLS-II and how to go about continuing-testing is covered.

  8. Treatment of mucocele of the lower lip with diode laser in pediatric patients: presentation of 2 clinical cases.

    PubMed

    Pedron, Irineu Gregnanin; Galletta, Vivian Cunha; Azevedo, Luciane Hiramatsu; Corrêa, Luciana

    2010-01-01

    Mucoceles are common benign lesions of the oral cavity that develop following extravasation or retention of mucous material from salivary glands in the subepithelial tissue. Most dental literature reports a higher incidence of mucocele in young patients, with trauma being a leading cause. Treatment may be performed by conventional surgery, cryotherapy, and, more recently, laser surgery and loser vaporization. The purpose of this report was to describe 2 clinical cases of lower-lip mucoceles treated by excision with a high-intensity diode laser in pediatric patients. Diode laser surgery was rapid, bloodless, and well accepted by patients. Postoperative problems, discomfort, and scarring were minimal. Treatment of mucoceles with high-intensity diode loser provided satisfactory results in the cases presented and allowed for a histopathological examination of the excised tissue. PMID:21462769

  9. Treatment of mucocele of the lower lip with diode laser in pediatric patients: presentation of 2 clinical cases.

    PubMed

    Pedron, Irineu Gregnanin; Galletta, Vivian Cunha; Azevedo, Luciane Hiramatsu; Corrêa, Luciana

    2010-01-01

    Mucoceles are common benign lesions of the oral cavity that develop following extravasation or retention of mucous material from salivary glands in the subepithelial tissue. Most dental literature reports a higher incidence of mucocele in young patients, with trauma being a leading cause. Treatment may be performed by conventional surgery, cryotherapy, and, more recently, laser surgery and loser vaporization. The purpose of this report was to describe 2 clinical cases of lower-lip mucoceles treated by excision with a high-intensity diode laser in pediatric patients. Diode laser surgery was rapid, bloodless, and well accepted by patients. Postoperative problems, discomfort, and scarring were minimal. Treatment of mucoceles with high-intensity diode loser provided satisfactory results in the cases presented and allowed for a histopathological examination of the excised tissue.

  10. Laser Materials and Laser Spectroscopy - A Satellite Meeting of IQEC '88

    NASA Astrophysics Data System (ADS)

    Wang, Zhijiang; Zhang, Zhiming

    1989-03-01

    The Table of Contents for the book is as follows: * Laser Materials * Laser Site Spectroscopy of Transition Metal Ions in Glass * Spectroscopy of Chromium Doped Tunable Laser Materials * Spectroscopic Properties of Nd3+ Ions in LaMgAl11O19 Crystal * Spectral Study and 2.938 μm Laser Emission of Er3+ in the Y3Al5O12 Crystal * Raman-infrared Spectra and Radiationless Relaxation of Laser Crystal NdAl3(BO3)4 * A Study on HB and FLN in BaFCl0.5Br0.5:Sm2+ at 77K * Pair-pumped Upconversion Solid State Lasers * CW Upconversion Laser Action in Neodymium and Erbium doped Solids * Ultra-high Sensitive Upconversion Fluorescence of YbF3 Doped with Trace Tm3+ and Er3+ * The Growth and Properties of NYAB and EYAB Multifunctional Crystal * Study on Fluorescence and Laser Light of Er3+ in Glass * Growth and Properties of Single Crystal Fibers for Laser Materials * A Study on the Quality of Sapphire, Ruby and Ti3+ Doped Sapphire Grown by Temperature Gradient Technique (TGT) and Czochralski Technique (CZ) * The Measurement of Output Property of Ti3+ Al2O3 Laser Crystal * An Xα Study of the Laser Crystal MgF2 : V2+ * Q-switched NAB Laser * Miniature YAG Lasers * Study of High Efficiency {LiF}:{F}^-_2 Color Center Crystals * Study on the Formation Conditions and Optical Properties of (F2+)H Color Center in NaCl:OH- Crystals * Novel Spectroscopic Properties of {LiF}:{F}^+_3 - {F}_2 Mixed Color Centers Laser Crystals * Terraced Substrate Visible GaAlAs Semiconductor Lasers with a Large Optical Cavity * The Temperature Dependence of Gain Spectra, Threshold Current and Auger Recombination in InGaAsP-InP Double Heterojunction Laser diode * Time-resolved Photoluminescence and Energy Transfer of Bound Excitons in GaP:N Crystals * Optical Limiting with Semiconductors * A Critical Review of High-efficiency Crystals for Tunable Lasers * Parametric Scattering in β - BaB2O4 Crystal Induced by Picosecond Pulses * Generation of Picosecond Pulses at 193 nm by Frequency Mixing in β - BaB2O4

  11. Ultrashort laser pulse cell manipulation using nano- and micro- materials

    NASA Astrophysics Data System (ADS)

    Schomaker, Markus; Killian, Doreen; Willenbrock, Saskia; Diebold, Eric; Mazur, Eric; Bintig, Willem; Ngezahayo, Anaclet; Nolte, Ingo; Murua Escobar, Hugo; Junghanß, Christian; Lubatschowski, Holger; Heisterkamp, Alexander

    2010-08-01

    The delivery of extra cellular molecules into cells is essential for cell manipulation. For this purpose genetic materials (DNA/RNA) or proteins have to overcome the impermeable cell membrane. To increase the delivery efficiency and cell viability of common methods different nano- and micro material based approaches were applied. To manipulate the cells, the membrane is in contact with the biocompatible material. Due to a field enhancement of the laser light at the material and the resulting effect the cell membrane gets perforated and extracellular molecules can diffuse into the cytoplasm. Membrane impermeable dyes, fluorescent labelled siRNA, as well as plasmid vectors encoded for GFP expression were used as an indicator for successful perforation or transfection, respectively. Dependent on the used material, perforation efficiencies over 90 % with a cell viability of about 80 % can be achieved. Additionally, we observed similar efficiencies for siRNA transfection. Due to the larger molecule size and the essential transport of the DNA into the nucleus cells are more difficult to transfect with GFP plasmid vectors. Proof of principle experiments show promising and adequate efficiencies by applying micro materials for plasmid vector transfection. For all methods a weakly focused fs laser beam is used to enable a high manipulation throughput for adherent and suspension cells. Furthermore, with these alternative optical manipulation methods it is possible to perforate the membrane of sensitive cell types such as primary and stem cells with a high viability.

  12. Laser shocking of materials: Toward the national ignition facility

    NASA Astrophysics Data System (ADS)

    Meyers, M. A.; Remington, B. A.; Maddox, B.; Bringa, E. M.

    2010-01-01

    In recent years a powerful experimental tool has been added to the arsenal at the disposal of the materials scientist investigating materials response at extreme regimes of strain rates, temperatures, and pressures: laser compression. This technique has been applied successfully to mono-, poly-, and nanocrystalline metals and the results have been compared with predictions from analytical models and molecular dynamics simulations. Special flash x-ray radiography and flash x-ray diffraction, combined with laser shock propagation, are yielding the strength of metals at strain rates on the order of 107-108 s-1 and resolving details of the kinetics of phase transitions. A puzzling result is that experiments, analysis, and simulations predict dislocation densities that are off by orders of magnitude. Other surprises undoubtedly await us as we explore even higher pressure/strain rate/temperature regimes enabled by the National Ignition Facility.

  13. Radiation damage of laser materials. Citations from the NTIS data base

    NASA Astrophysics Data System (ADS)

    Carrigan, B.

    1980-05-01

    Laser beam damage to laser materials such as optical glass, glass fibers, alkali metal halides, metals, mirrors, optical coatings, dielectrics, semiconductors, and matrix materials is studied. The majority of these citations concern infrared laser damage to infrared optical materials. This updated bibliography contains 217 abstracts, 10 of which are new entries to the previous edition.

  14. Present Status and Future Prospects of Laser Fusion Research at ILE Osaka University

    NASA Astrophysics Data System (ADS)

    Mima, K.; Tanaka, K. A.; Kodama, R.; Johzaki, T.; Nagatomo, H.; Shiraga, H.; Sentoku, Y.; Miyanaga, N.; Azechi, H.; Nakai, M.; Norimatu, T.; Nagai, K.; Sunanara, J.; Nishihara, K.; Taguchi, T.; Sakagami, H.

    2004-02-01

    Reviewed are the present status and future prospects of the laser fusion research at the ILE Osaka. The Gekko XII and Peta Watt laser system have been operated for investigating the implosion hydrodynamics, fast ignition, and the relativistic laser plasma interactions and so on. In particular, the fast ignition experiments with cone shell target have been in progress as the UK and US-Japan collaboration programs. In the experiments, the imploded high density plasmas are heated by irradiating 500 J level peta-watt laser pulse. The thermal neutron yield is found to increase by three orders of magnitude by injecting the peta-watt laser into the cone shell target. The Rayleigh-Taylor instability experiment results are also reviewed is this paper.

  15. Tunable solid state lasers

    SciTech Connect

    Hammerling, R.; Budgor, A.B.; Pinto, A.

    1985-01-01

    This book presents the papers given at a conference on solid state lasers. Topics considered at the conference included transition-metal-doped lasers, line-narrowed alexandrite lasers, NASA specification, meteorological lidars, laser materials spectroscopy, laser pumped single pass gain, vibronic laser materials growth, crystal growth methods, vibronic laser theory, cross-fertilization through interdisciplinary fields, and laser action of color centers in diamonds.

  16. Development of High Power Lasers for Materials Interactions

    SciTech Connect

    Hackel, L A

    2003-04-11

    radiation for radiography, particle beam generation and eventually for a new class of fusion experiments call fast ignition. We have also built a record setting 50 watts of average output from a picosecond class laser and are using this technology for materials processing such as fine hole drilling and safe cutting of munitions. The laser science and technology program has developed and deployed a laser guide star on the Lick telescope on Mt. Hamilton and most recently on the Keck telescope in Hawaii. Our current development work in this area is focused on developing a much more compact all solid state diode pumped laser fiber system. Finally in a program originally initiated by DARPA we have developed a phase conjugated Nd:glass laser system with record setting performance and successfully deployed it for Navy and Air Force satellite imaging applications and have more recently successfully transferred it to industry for use in an emerging technology called laser peening. This laser technology is capable of 25 J to 100 J per pulse, 10 ns to 1000 ns pulse duration, 5 Hz laser. The technology has been industrially deployed and is proving to be highly effective in generating high intensity shocks that induce compressive residual stress into metal components. The compressive stress retards fatigue and stress corrosion cracking and is proving to extend the lifetime of high value components by factors of ten. This processing adds lifetime, enhances safety and can improve performance of aircraft systems. Laser peening is now being evaluated to reduce the weight of aircraft and may play a major role in the future combat system and its air transport by enabling lighter craft, longer range and greater payload. The laser peening technology is also being moved forward in NRC license application as the means to eliminate stress corrosion cracking for Yucca Mountain nuclear waste disposal canisters as well as a broad range of other applications.

  17. Inorganic Photovoltaics Materials and Devices: Past, Present, and Future

    NASA Technical Reports Server (NTRS)

    Hepp, Aloysius F.; Bailey, Sheila G.; Rafaelle, Ryne P.

    2005-01-01

    This report describes recent aspects of advanced inorganic materials for photovoltaics or solar cell applications. Specific materials examined will be high-efficiency silicon, gallium arsenide and related materials, and thin-film materials, particularly amorphous silicon and (polycrystalline) copper indium selenide. Some of the advanced concepts discussed include multi-junction III-V (and thin-film) devices, utilization of nanotechnology, specifically quantum dots, low-temperature chemical processing, polymer substrates for lightweight and low-cost solar arrays, concentrator cells, and integrated power devices. While many of these technologies will eventually be used for utility and consumer applications, their genesis can be traced back to challenging problems related to power generation for aerospace and defense. Because this overview of inorganic materials is included in a monogram focused on organic photovoltaics, fundamental issues and metrics common to all solar cell devices (and arrays) will be addressed.

  18. ICALEO '90: Laser materials processing; Proceedings of the Meeting, Boston, MA, Nov. 4-9, 1990

    SciTech Connect

    Ream, S.L.; Dausinger, F.; Fujioka, Tomoo.

    1991-01-01

    Recent developments in high-power CO2 laser technology used in industrial materials processing are discussed in reviews and reports. Consideration is given to practical beam characterization parameters and a variety of measurement techniques for these lasers. Topics discussed include beam measurements and diagnostics, beam delivery and beam shaping, high-power rod and slab lasers, advances in laser drilling, the maturing of laser cutting, novel processes, laser welding, and surface modification.

  19. Hyperspectral and gated ICCD imagery for laser irradiated carbon materials

    NASA Astrophysics Data System (ADS)

    Roberts, Charles D.; Acosta, Roberto A.; Marciniak, Michael A.; Perram, Glen P.

    2013-02-01

    New optical diagnostics for studying laser ablation and induced combustion for carbon materials are key to monitoring the evolving, spatial distribution of the gas plume. We are developing high speed imaging FTIR and gated ICCD imagery for materials processing, manufacture process control, and high energy laser applications. The results from two projects will be discussed. First, an imaging Fourier Transform Spectrometer with a 320 x 256 InSb focal plane array frames at 1.9 kHz with a spatial resolution of 1 mm and spectral resolution of up to 0.25 cm-1. Gas phase plumes above the surface of laser-irradiated black plexiglass, fiberglass and painted thin metals have been spectrally resolved. Molecular emission from CO, CO2, H2O, and hydrocarbons is readily identified. A line-by-line radiative transfer model is used to derive movies for specie concentrations and temperatures. Second, excimer laser pulsed ablation of bulk graphite into low-pressure (0.05 - 1 Torr) argon generates highly ionized, high speed (M>40) plumes. A gated, intensified CCD camera with band pass filtering has been used to generate plume imagery with temporal resolution of 10ns. The Sedov-Taylor shock model characterizes the propagation of the shock front if the dimensionality of the plume is allowed to deviate from ideal spherical expansion. A drag model is more appropriate when the plume approaches extinction (~10 μs) and extends the characterization into the far field. Conversion of laser pulse energy to the shock is efficient.

  20. Emission Spectrochemical Analysis of Food Material Using TEA CO2 Laser-Induced Shock Wave Plasma

    NASA Astrophysics Data System (ADS)

    Kagawa, Kiichiro; Deguchi, Yoji; Ogata, Akira; Kurniawan, Hendrick; Ikeda, Noriko; Takagi, Yasuhiro

    1991-11-01

    A new method for spectrochemical analysis of food materials is presented using a Transverse Excited Atmospheric (TEA) CO2 laser. Milk powders containing different amounts of Ca are mixed with KBr powder, and compressed to make pellets. The pellets are bombarded by the TEA CO2 laser (300 mJ, 100 ns) under the surrounding gas of 300 Pa. The shape of the luminous plasma is hemispherical. This plasma is excited by the shock wave induced by the laser bombardment. It is proved that the relative intensity of the Ca 422.6-nm emission line to that of the K 404.4-nm emission line is proportional to the Ca content. This method has a bright prospect as a direct analytical method of food materials.

  1. Vanderbilt Free-Electron Laser Center for Biomedical and Materials Research

    NASA Astrophysics Data System (ADS)

    Tolk, Norman H.; Brau, Charles A.; Edwards, Glenn S.; Margaritondo, Giorgio; McKinley, Jim T.

    1991-12-01

    The newly commissioned Vanderbilt Free Electron Laser Center for Biomedical and Materials Research is a multidisciplinary users facility intended as an international resource. It provides extremely intense, continuously tunable, pulsed radiation in the mid-infrared (2-10 j.tm). Projects already underway include the linear and nonlinear interaction of laser radiation with optical materials, semiconductors, and mammalian tissue, the spectroscopy of species adsorbed on surfaces, measurement of vibrational energy transfer in DNA and RNA, the dynamics of proteins in cell membranes, the biomodulation of wound healing by lasers, image-guided stereotactic neurosurgery, and the use of monochromatic X-rays in medical imaging and therapy. The purpose of this article is to introduce the machine to the user community and to describe some of the new experimental opportunities that it makes possible. Details of several research projects are presented.

  2. Predicting the Performance of Edge Seal Materials for PV (Presentation)

    SciTech Connect

    Kempe, M.; Panchagade, D.; Dameron, A.; Reese, M.

    2012-03-01

    Edge seal materials were evaluated using a 100-nm film of Ca deposited on glass and laminated to another glass substrate. As moisture penetrates the package it converts the Ca metal to transparent CaOH2 giving a clear indication of the depth to which moisture has entered. Using this method, we have exposed test samples to a variety of temperature and humidity conditions ranging from 45C and 10% RH up to 85C and 85% RH, to ultraviolet radiation and to mechanical stress. We are able to show that edge seal materials are capable of keeping moisture away from sensitive cell materials for the life of a module.

  3. DOE Automotive Composite Materials Research: Present and Future Efforts

    SciTech Connect

    Warren, C.D.

    1999-08-10

    One method of increasing automotive energy efficiency is through mass reduction of structural components by the incorporation of composite materials. Significant use of glass reinforced polymers as structural components could yield a 20--30% reduction in vehicle weight while the use of carbon fiber reinforced materials could yield a 40--60% reduction in mass. Specific areas of research for lightweighting automotive components are listed, along with research needs for each of these categories: (1) low mass metals; (2) polymer composites; and (3) ceramic materials.

  4. Laser-based microstructuring of materials surfaces using low-cost microlens arrays

    NASA Astrophysics Data System (ADS)

    Nieto, Daniel; Vara, G.; Diez, J. A.; O`Connor, Gerard M.; Arines, Justo; Gómez-Reino, C.; Flores-Arias, M.

    2012-03-01

    Since frictional interactions in microscopically small components are becoming increasingly important for the development of new products for all modern technology, we present a laser-based technique for micro-patterning surfaces of materials using low-cost microlens arrays. The microlens used were fabricated on soda-lime glass using a laser direct-write technique, followed by a thermal treatment into an oven. By combining laser direct-write and the thermal treatment it was possible to obtain high quality elements using a low cost infrared laser widely implemented in industry which makes this technique attractive in comparison with other more expensive methods. The main advantage of using microlens arrays for micropatterning surfaces is the possibility of fabricating a large number of identical structures simultaneously, leading to a highly efficient process. In order to study the capabilities of the microlens fabricated for microstructuring materials, identical structures and arrays of holes were fabricated over a variety of materials, such us, stainless steel, polymer and ceramic. The minimum diameter of the individual microstructure generated at surface is 5 μm. Different nanosecond lasers operating at Infrared, Green and UV were used. The topography and morphology of the elements obtained were determined using a confocal microscope SENSOFAR 2300 Plμ.

  5. A kilowatt average power laser for sub-picosecond materials processing

    SciTech Connect

    Stephen V. Benson; George R. Neil; C. Bohn; , G. Biallas; D. Douglas; F. Dylla; J. Fugitt; K. Jordan; G. Krafft; , L. Merminga; , J. Preble; , Michelle D. Shinn; T. Siggins; R. Walker; B. Yunn

    1999-11-01

    The performance of laser pulses in the sub-picosecond range for materials processing is substantially enhanced over similar fluences delivered in longer pulses. Recent advances in the development of solid state lasers have progressed significantly toward the higher average powers potentially useful for many applications. Nonetheless, prospects remain distant for multi-kilowatt sub-picosecond solid state systems such as would be required for industrial scale surface processing of metals and polymers. The authors present operational results from the world's first kilowatt scale ultra-fast materials processing laser. A Free Electron Laser (FEL) called the IR Demo is operational as a User Facility at Thomas Jefferson National Accelerator Facility in Newport News, Virginia, USA. In its initial operation at high average power it is capable of wavelengths in the 2 to 6 micron range and can produce {approximately}0.7 ps pulses in a continuous train at {approximately}75 MHz. This pulse length has been shown to be nearly optimal for deposition of energy in materials at the surface. Upgrades in the near future will extend operation beyond 10 kW CW average power in the near IR and kilowatt levels of power at wavelengths from 0.3 to 60 microns. This paper will cover the design and performance of this groundbreaking laser and operational aspects of the User Facility.

  6. Thermal Protection Materials and Systems: Past, Present, and Future

    NASA Technical Reports Server (NTRS)

    Johnson, Sylvia M.

    2013-01-01

    Thermal protection materials and systems (TPS) protect vehicles from the heat generated when entering a planetary atmosphere. NASA has developed many TPS systems over the years for vehicle ranging from planetary probes to crewed vehicles. The goal for all TPS is efficient and reliable performance. Efficient means using the right material for the environment and minimizing the mass of the heat shield without compromising safety. Efficiency is critical if the payload such as science experiments is to be maximized on a particular vehicle. Reliable means that we understand and can predict performance of the material. Although much characterization and testing of materials is performed to qualify and certify them for flight, it is not possible to completely recreate the reentry conditions in test facilities, and flight-testing

  7. Present status and future outlook of selective metallization for electronics industry by laser irradiation to metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Watanabe, Akira

    2015-03-01

    Recently an alternative to conventional methods based on vacuum processes such as evaporation or sputtering is desired to reduce the energy consumption and the environmental impact. Printed electronics has been developed as a one of the candidates, which is based on wet processes using soluble functional materials such as organic semiconductors, inorganic nanomaterials, organic-inorganic hybrids, and so on. Although inkjet printing has been studied widely as a core technology of printed electronics, the limitation of resolution is around 20 micrometer. The combination of the inkjet printing with other selective metallization process is necessary because the resolution of several micrometers is required in some optical and electrical devices. The laser processing has emerged as an attractive technique in microelectronics because of the fascinating features such as high resolution, high degree of flexibility to control the resolution and size of the micro-patterns, high speed, and a little environmental pollution. In this paper, the present status and future outlook of selective metallization for interconnection and the formation of transparent conductive film based on the laser processing using metal nanoparticles were reported. The laser beam irradiation to metal nanoparticles causes the fast and efficient sintering by plasmon resonance of metal nanoparticle, where the absorbed energy is confined in a nanoparticle and the nanoparticle acts as a nano-heater. The laser irradiation to metal nanoparticles was applied to the laser direct writing of metal wiring and micropatterns using silver and copper nanoparticles.

  8. CRC handbook of laser science and technology. Volume 4. Optical materials, Part 2 - Properties

    SciTech Connect

    Weber, M.J.

    1986-01-01

    This book examines the optical properties of laser materials. Topics considered include: fundamental properties; transmitting materials; crystals; glasses; plastics; filter materials; mirror and reflector materials; polarizer materials; special properties; linear electrooptic materials; magnetooptic materials; elastooptic materials; photorefractive materials; and liquid crystals.

  9. New materials strategies for creating hybrid electronic circuitry (Presentation Video)

    NASA Astrophysics Data System (ADS)

    Marks, Tobin J.

    2013-09-01

    This lecture focuses on the challenging design and realization of new materials for creating unconventional electronic circuitry. Fabrication methodologies to achieve these goals include high-throughput, large-area printing techniques. Materials design topics to be discussed include: 1. Rationally designed high-mobility p- and n-type organic semiconductors for printed organic CMOS, 2. Polycrystalline and amorphous oxide semiconductors for transparent and mechanically flexible electronics, 3) Self-assembled and printable high-k nanodielectrics enabling ultra-large capacitance, low leakage, high breakdown fields, minimal trapped interfacial charge, and device radiation hardness. 4) Combining these materials sets to fabricate a variety of high-performance thin-film transistor-based devices.

  10. Micromachining of transparent materials by laser ablation of organic solution

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Niino, Hiroyuki; Yabe, Akira

    2000-11-01

    Transparent materials such as fused silica, quartz, calcium fluoride, and fluorocarbon polymer were etched upon irradiation of organic solution containing pyrene with a conventional KrF excimer laser. Threshold fluence for etching was 240 mJ/cm2 for fused silica. Etch rate remarkably depended on a concentration of pyrene: higher etch rate with the increase of pyrene concentration. It means that pyrene molecules play an important role in this process. The etch rate can be easily controlled through changing a laser pulse number, a laser fluence and a concentration of solution. The mechanism for this process is discussed by cyclic multiphotonic absorption of pyrene in the excited states, thermal relaxation, and formation of super-heated solution. As the results, it is suggested that the process is based on the combination of two processes in the interface between the transparent materials and the liquid: one is a heating process by a super-heated liquid and the other is an attacking process by a high temperature and pressure vapor.

  11. Laser annealed in-situ P-doped Ge for on-chip laser source applications (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Srinivasan, Ashwyn; Pantouvaki, Marianna; Shimura, Yosuke; Porret, Clement; Van Deun, Rik; Loo, Roger; Van Thourhout, Dries; Van Campenhout, Joris

    2016-05-01

    Realization of a monolithically integrated on-chip laser source remains the holy-grail of Silicon Photonics. Germanium (Ge) is a promising semiconductor for lasing applications when highly doped with Phosphorous (P) and or alloyed with Sn [1, 2]. P doping makes Ge a pseudo-direct band gap material and the emitted wavelengths are compatible with fiber-optic communication applications. However, in-situ P doping with Ge2H6 precursor allows a maximum active P concentration of 6×1019 cm-3 [3]. Even with such active P levels, n++ Ge is still an indirect band gap material and could result in very high threshold current densities. In this work, we demonstrate P-doped Ge layers with active n-type doping beyond 1020 cm-3, grown using Ge2H6 and PH3 and subsequently laser annealed, targeting power-efficient on-chip laser sources. The use of Ge2H6 precursors during the growth of P-doped Ge increases the active P concentration level to a record fully activated concentration of 1.3×1020 cm-3 when laser annealed with a fluence of 1.2 J/cm2. The material stack consisted of 200 nm thick P-doped Ge grown on an annealed 1 µm Ge buffer on Si. Ge:P epitaxy was performed with PH3 and Ge2H6 at 320oC. Low temperature growth enable Ge:P epitaxy far from thermodynamic equilibrium, resulting in an enhanced incorporation of P atoms [3]. At such high active P concentration, the n++ Ge layer is expected to be a pseudo-direct band gap material. The photoluminescence (PL) intensities for layers with highest active P concentration show an enhancement of 18× when compared to undoped Ge grown on Si as shown in Fig. 1 and Fig. 2. The layers were optically pumped with a 640 nm laser and an incident intensity of 410 mW/cm2. The PL was measured with a NIR spectrometer with a Hamamatsu R5509-72 NIR photomultiplier tube detector whose detectivity drops at 1620 nm. Due to high active P concentration, we expect band gap narrowing phenomena to push the PL peak to wavelengths beyond the detection limit

  12. CIGS Material and Device Stability: A Processing Perspective (Presentation)

    SciTech Connect

    Ramanathan, K.

    2012-03-01

    This is a general overview of CIGS material and device fundamentals. In the first part, the basic features of high efficiency CIGS absorbers and devices are described. In the second part, some examples of previous collaboration with Shell Solar CIGSS graded absorbers and devices are shown to illustrate how process information was used to correct deviations and improve the performance and stability.

  13. Significant residual fluorinated alcohols present in various fluorinated materials.

    PubMed

    Dinglasan-Panlilio, Mary Joyce A; Mabury, Scott A

    2006-03-01

    Polyfluorinated telomer alcohols and sulfonamides are classes of compounds recently identified as precursor molecules to the perfluorinated acids detected in the environment. Despite the detection and quantification of these volatile compounds in the atmosphere, their sources remain unknown. Both classes of compounds are used in the synthesis of various fluorosurfactants and incorporated in polymeric materials used extensively in the carpet, textile, and paper industries. This study has identified the presence of residual unbound fluoro telomer alcohols (FTOHs) in varying chain lengths (C6-C14) in several commercially available and industrially applied polymeric and surfactant materials. NMeFOSE, a perfluoroalkyl sulfonamido alcohol, was also detected in a commercially available carpet protector product. A method was developed to remove these residual compounds from polymeric and surfactant materials by dispersion in water and stripping of the volatiles using a constant flow of air and trapping on XAD resin. Using gas chromatography mass spectrometry analysis, it was determined that the fluorinated materials examined consist of 0.04-3.8% residual alcohols on a fluoro alcohol to dry mass basis. These values indicate that residual alcohols, left unreacted and unbound from the manufacturing process of fluorinated polymers and surfactants, could be a significant source of the polyfluorinated telomer alcohols and sulfonamides released into the environment. This study suggests that elimination or reduction of these residual alcohols from all marketed fluorinated polymers and fluorosurfactants is key in reducing the prevalence of perfluorinated acids formed in the environment.

  14. Insider Threat - Material Control and Accountability Mitigation (Presentation)

    SciTech Connect

    Powell, Danny H; Elwood Jr, Robert H

    2011-01-01

    Why is the insider a concern? There are many documented cases of nuclear material available for sale - there are more insider diversions than outsider attacks and more than 18 documented cases of theft or loss of plutonium or highly enriched uranium. Insider attributes are: have access, has authority, possesses knowledge, works with absence of timeline, can test system, and may act alone or support a team. Material control and accountability (MC&A) is an essential part of an integrated safeguards system. Objectives of MC&A are: (1) Ongoing confirmation of the presence of special nuclear material (SNM) in assigned locations; (2) Prompt investigation of anomalies that may indicate a loss of SNM; (3) Timely and localized detection of loss, diversion, or theft of a goal quantity; (4) Rapid assessment and response to detection alarms; and (5) Timely generation of information to aid in the recovery of SNM in the event of an actual loss, diversion, or theft from the purview of the MC&A system. Control and accountability of material, equipment, and data are essential to minimizing insider threats.

  15. Standoff detection of hazardous materials using a novel dual-laser pulse technique: theory and experiments

    NASA Astrophysics Data System (ADS)

    Ford, Alan; Waterbury, Robert D.; Rose, Jeremy; Dottery, Edwin L.

    2009-05-01

    The present work focuses on a new variant of double pulse laser induced breakdown spectroscopy (DP-LIBS) called Townsend effect plasma spectroscopy (TEPS) for standoff applications. In the TEPS technique, the atomic and molecular emission lines are enhanced by a factor on the order of 25 to 300 times over LIBS, depending upon the emission lines observed. As a result, it is possible to extend the range of laser induced plasma techniques beyond LIBS and DP-LIBS for the detection of CBRNE materials at distances of several meters.

  16. Rapid microfabrication of transparent materials using filamented femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Butkus, S.; Gaižauskas, E.; Paipulas, D.; Viburys, Ž.; Kaškelyė, D.; Barkauskas, M.; Alesenkov, A.; Sirutkaitis, V.

    2014-01-01

    Microfabrication of transparent materials using femtosecond laser pulses has showed good potential towards industrial application. Maintaining pulse energies exceeding the critical self-focusing threshold by more than 100-fold produced filaments that were used for micromachining purposes. This article demonstrates two different micromachining techniques using femtosecond filaments generated in different transparent media (water and glass). The stated micromachining techniques are cutting and welding of transparent samples. In addition, cutting and drilling experiments were backed by theoretical modelling giving a deeper insight into the whole process. We demonstrate cut-out holes in soda-lime glass having thickness up to 1 mm and aspect ratios close to 20, moreover, the fabrication time is of the order of tens of seconds, in addition, grooves and holes were fabricated in hardened 1.1 mm thick glass (Corning Gorilla glass). Glass welding was made possible and welded samples were achieved after several seconds of laser fabrication.

  17. Damage thresholds in laser-irradiated optical materials

    NASA Astrophysics Data System (ADS)

    Guignard, Franck; Autric, Michel L.; Baudinaud, Vincent

    1997-05-01

    An experimental study on the damage induced by laser irradiation on different materials, borosilicate glass, fused silicate, molded and stretched polymethylmethacrylate (PMMA), has been performed. The irradiation source is a 1KL pulsed cold cathode electron gun preionized TEA CO2 laser. Damage mechanisms are controlled by the in-depth absorption of the 10.6 micrometers radiation according to the Beer-Lambert law. PMMA is damaged following a boiling process. Stretched PMMA is fractured first, releasing stresses, then boiled like molded PMMA at a higher energy. BK7 crazed after the irradiation due to thermomechanical stresses, silicate melt and vaporized. Optical damages have been characterized by measuring the contrast transfer function through the irradiated samples.

  18. Advanced Material Developments with Laser Engineered Net Shaping

    NASA Technical Reports Server (NTRS)

    Williams, Glenn A.; Cooper, Ken; McGill, Preston; Munafo, Paul M. (Technical Monitor)

    2002-01-01

    The Laser Engineered Net Shaping (LENS(Trademark)) process is a new technology to fabricate three-dimensional metallic components directly from CAD solid models. It directly fabricates metal hardware by injecting the metal powder of choice into the focal point of a 700W Nd:Yag laser as it traces the perimeter and fills of a part. The Rapid Prototype Laboratory at Marshall Space Flight Center is currently operating a OPTOMEC 750 LENS machine in evaluation experiments involving integration of this technology into various manufacturing processes associated with aerospace applications. This paper will cover our research finding about properties of samples created from Inconel 718 & SS316 using this process versus the same materials in cast & wrought conditions.

  19. Ultrafast Dynamic Ellipsometry And Spectroscopy Of Laser Shocked Materials

    SciTech Connect

    McGrane, S. D.; Bolme, C. A.; Whitley, V. H.; Moore, D. S.

    2010-10-08

    Shock waves create extreme states of matter with very high pressures, temperatures, and volumetric compressions, at an exceedingly rapid rate of change. We review how to use a beamsplitter and a note card to turn a typical chirp pulse amplified femtosecond laser system into an ultrafast shock dynamics machine. Open scientific questions that can be addressed with such an apparatus are described. We report on the development of several single shot time resolved diagnostics needed to answer these questions. These single shot diagnostics are expected to be broadly applicable to other types of laser ablation experiments. Experimental results measured from shocked material dynamics of several systems are detailed. Finally, we report on progress towards using transient absorption as a measure of electronic excitation and coherent Raman as a picosecond probe of temperature in shock compressed condensed matter.

  20. Ultrafast dynamic ellipsometry and spectroscopy of laser shocked materials

    SciTech Connect

    Mcgrane, Shawn David; Bolme, Cindy B; Whitley, Von H; Moore, David S

    2010-01-01

    Shock waves create extreme states of matter with very high pressures, temperatures, and volumetric compressions, at an exceedingly rapid rate of change. We review how to use a beamsplitter and a note card to turn a typical chirp pulse amplified femtosecond laser system into an ultrafast shock dynamics machine. Open scientific questions that can be addressed with such an apparatus are described. We report on the development of several single shot time resolved diagnostics needed to answer these questions. These single shot diagnostics are expected to be broadly applicable to other types of laser ablation experiments. Experimental results measured from shocked material dynamics of several systems are detailed. Finally, we report on progress towards using transient absorption as a measure of electronic excitation and coherent Raman as a picosecond probe of temperature in shock compressed condensed matter.

  1. Qualification of diode foil materials for excimer lasers

    NASA Astrophysics Data System (ADS)

    Anderson, R. G.; Shurter, R. P.; Rose, E. A.

    The Aurora facility at Los Alamos National Laboratory uses KrF excimer lasers to produce 248 nm light for inertial confinement fusion applications. Diodes in each amplifier produce relativistic electron beams to pump a Kr-F-Ar gas mixture. A foil is necessary to separate the vacuum diode from the laser gas. High tensile strength, high electron transmission, low ultraviolet reflectivity, and chemical compatibility with fluorine have been identified as requisite foil properties. Several different materials were acquired and tested for use as diode foils. Transmission and fluorine compatibility tests were performed using the Electron Gun Test Facility (EGTF) at Los Alamos. Off-line tests of tensile strength and reflectivity were performed. Titanium foil, which is commonly used as a diode foil, was found to generate solid and gaseous fluoride compounds, some of which are highly reactive in contact with water vapor.

  2. Laser-solid interaction and dynamics of the laser-ablated materials

    SciTech Connect

    Chen, K.R.; Leboeuf, J.N.; Geohegan, D.B.; Wood, R.F.; Donato, J.M.; Liu, C.L.; Puretzky, A.A.

    1995-07-01

    Rapid transformations through the liquid and vapor phases induced by laser-solid interactions are described by the authors` thermal model with the Clausius-Clapeyron equation to determine the vaporization temperature under different surface pressure condition. Hydrodynamic behavior of the vapor during and after ablation is described by gas dynamic equations. These two models are coupled. Modeling results show that lower background pressure results lower laser energy density threshold for vaporization. The ablation rate and the amount of materials removed are proportional to the laser energy density above its threshold. The authors also demonstrate a dynamic source effect that accelerates the unsteady expansion of laser-ablated material in the direction perpendicular to the solid. A dynamic partial ionization effect is studied as well. A self-similar theory shows that the maximum expansion velocity is proportional to c{sub s}{alpha}, where 1 {minus} {alpha} is the slope of the velocity profile. Numerical hydrodynamic modeling is in good agreement with the theory. With these effects, {alpha} is reduced. Therefore, the expansion front velocity is significantly higher than that from conventional models. The results are consistent with experiments. They further study how the plume propagates in high background gas condition. Under appropriate conditions, the plume is slowed down, separates with the background, is backward moving, and hits the solid surface. Then, it splits into two parts when it rebounds from the surface. The results from the modeling will be compared with experimental observations where possible.

  3. Present and Future Automotive Composite Materials Research Efforts at DOE

    SciTech Connect

    Warren, C.D.

    1999-07-03

    Automobiles of the future will be forced to travel fi.uther on a tank of fuel while discharging lower levels of pollutants. Currently, the United States uses in excess of 16.4 million barrels of petroleum per day. Sixty-six percent of that petroleum is used in the transportation of people and goods. Automobiles currently account for just under two-thirds of the nation's gasoline consumptio~ and about one-third of the total United States energy usage. [1] By improving transportation related fiel efficiency, the United States can lessen the impact that emissions have on our environment and provide a cleaner environment for fiture generations. In 1992, The Department of Energy's (DOE) Office of Transportation Materials completed a comprehensive program plan entitled, The Lightweight MateriaIs (LWko Multi-Year Program Plan, for the development of technologies aimed at reducing vehicle mass [2]. This plan was followed in 1997 by the more comprehensive Office of Advanced Automotive Technologies research and development plan titled, Energy Eficient Vehicles for a Cleaner Environment [3] which outlines the department's plans for developing more efficient vehicles during the next ~een years. Both plans identi~ potential applications, technology needs, and R&D priorities. The goal of the Lightweight Materials Program is to develop materials and primary processing methods for the fabrication of lighter weight components which can be incorporated into automotive systems. These technologies are intended to reduce vehicle weight, increase fuel efficiency and decrease emissions. The Lightweight Materials program is jointly managed by the Department of Energy(DOE) and the United States Automotive Materials Partnership (USAMP). Composite materiak program work is coordinated by cooperative research efforts between the DOE and the Automotive Composites Consortium (ACC).

  4. Velocity measurements of inert porous materials driven by infrared-laser-ablated thin-film titanium

    NASA Astrophysics Data System (ADS)

    Bedeaux, Brett C.; Trott, Wayne M.; Castañeda, Jaime N.

    2010-02-01

    This article presents and interprets a series of experiments performed to measure the velocity of four inert low-density porous materials that were accelerated by an ablated thin-film titanium metal, created by vaporizing a 250-nm-thick layer of titanium with a high-energy, Q-switched, pulsed, and 1.054 μm neodymium-glass laser. Inert powder materials were chosen to match, among other characteristics, the morphology of energetic materials under consideration for use in detonator applications. The observed behavior occurs near the thin-film titanium ablation layer, through complex physical mechanisms, including laser absorption in the metal layer, ablation and formation of confined plasma that is a blackbody absorber of the remaining photon energy, and vaporization of the remaining titanium metal. One-dimensional hydrodynamic modeling provided a basis of comparison with the measured velocities. We found, as predicted in wave-propagation-code modeling, that an Asay foil can indicate total momentum of the driven material that is mechanically softer (lower in shock impedance) than the foil. The key conclusion is that the specific impulse delivered by the laser transfers a corresponding momentum to soft, organic power columns that are readily compacted. Impulse from the laser is less efficient in transferring momentum to hard inorganic particles that are less readily compacted.

  5. Analysis and removal of ITER relevant materials and deposits by laser ablation

    NASA Astrophysics Data System (ADS)

    Xiao, Qingmei; Huber, Alexander; Philipps, Volker; Sergienko, Gennady; Gierse, Niels; Mertens, Philippe; Hai, Ran; Ding, Hongbin

    2014-12-01

    The analysis of the deposition of eroded wall material on the plasma-facing materials in fusion devices is one of the crucial issues to maintain the plasma performance and to fulfill safety requirements with respect to tritium retention by co-deposition. Laser ablation with minimal damage to the plasma facing material is a promising method for in situ monitoring and removal of the deposition, especially for plasma-shadowed areas which are difficult to reach by other cleaning methods like plasma discharge. It requires the information of ablation process and the ablation threshold for quantitative analysis and effective removal of the different deposits. This paper presents systemic laboratory experimental analysis of the behavior of the ITER relevant materials, graphite, tungsten, aluminum (as a substitution of beryllium) and mixed deposits ablated by a Nd:YAG laser (1064 nm) with different energy densities (1-27 J/cm2, power density 0.3-3.9 GW/cm2). The mixed deposits consisted of W-Al-C layer were deposited on W substrate by magnetron sputtering and arc plasma deposition. The aim was to select the proper parameters for the quantitative analysis and for laser removal of the deposits by investigating the ablation efficiency and ablation threshold for the bulk materials and deposits. The comparison of the ablation and saturation energy thresholds for pure and mixed materials shows that the ablation threshold of the mixed layer depends on the concentration of the components. We propose laser induced breakdown spectroscopy for determination of the elemental composition of deposits and then we select the laser parameters for the layer removal. Comparison of quantitative analysis results from laboratory to that from TEXTOR shows reasonable agreements. The dependence of the spectra on plasma parameters and ambient gas pressure is investigated.

  6. Laser annealing and defect study of chalcogenide photovoltaic materials

    NASA Astrophysics Data System (ADS)

    Bhatia, Ashish

    Cu(In,Ga)Se2 (CIGSe), CuZnSn(S,Se)4(CZTSSe), etc., are the potential chalcogenide semiconductors being investigated for next-generation thin film photovoltaics (TFPV). While the champion cell efficiency of CIGSe has exceeded 20%, CZTSSe has crossed the 10% mark. This work investigates the effect of laser annealing on CISe films, and compares the electrical characteristics of CIGSe (chalcopyrite) and CZTSe (kesterite) solar cells. Chapter 1 through 3 provide a background on semiconductors and TFPV, properties of chalcopyrite and kesterite materials, and their characterization using deep level transient spectroscopy (DLTS) and thermal admittance spectroscopy (TAS). Chapter 4 investigates electrochemical deposition (nonvacuum synthesis) of CISe followed by continuous wave laser annealing (CWLA) using a 1064 nm laser. It is found that CWLA at ≈ 50 W/cm2 results in structural changes without melting and dewetting of the films. While Cu-poor samples show about 40% reduction in the full width at half maximum of the respective x-ray diffraction peaks, identically treated Cu-rich samples register more than 80% reduction. This study demonstrates that an entirely solid-phase laser annealing path exists for chalcopyrite phase formation and crystallization. Chapter 5 investigates the changes in defect populations after pulse laser annealing in submelting regime of electrochemically deposited and furnace annealed CISe films. DLTS on Schottky diodes reveal that the ionization energy of the dominant majority carrier defect state changes nonmonotonically from 215+/-10 meV for the reference sample, to 330+/-10 meV for samples irradiated at 20 and 30 mJ/cm2, and then back to 215+/-10 meV for samples irradiated at 40 mJ/cm2. A hypothesis involving competing processes of diffusion of Cu and laser-induced generation of In vacancies may explain this behavior. Chapter 6 compares the electrical characteristics of chalcopyrite and kesterite materials. Experiments reveal CZTSe cell has an

  7. Laser-Launched Flyer Plates and Direct Laser Shocks for Dynamic Material Property Measurements

    NASA Astrophysics Data System (ADS)

    Paisley, D. L.; Swift, D. C.; Johnson, R. P.; Kopp, R. A.; Kyrala, G. A.

    2002-07-01

    The Trident laser at Los Alamos was used to impart known and controlled shocks in various materials by launching flyer plates or by irradiating the sample directly. Materials investigated include copper, gold, NiTi, SS316, and other metals and alloys. Tensile spall strength, elastic-plastic transition, phase boundaries, and equation of state can be determined with small samples. Using thin samples (0.1 - 1.0 mm thick) as targets, high pressure gradients can be generated with relatively low pressures, resulting in high tensile strain rates (105 to 108 s-1). Free surface and interface velocities are recorded with point- and line-imaging VISARs. The flexible spatial and temporal pulse profiles of Trident, coupled with the use of laser-launched flyer plates, provides capabilities which complement experiments conducted using gas guns and tensile bars.

  8. Alternative materials lead to practical nanophotonic components (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Kinsey, Nathaniel; Ferrera, Marcello; DeVault, Clayton; Kim, Jongbum; Kildishev, Alexander V.; Shalaev, Vladimir M.; Boltasseva, Alexandra

    2015-09-01

    Recently, there has been a flurry of research in the field of alternative plasmonic materials, but for telecommunication applications, CMOS compatible materials titanium nitride and doped zinc oxides are among the most promising materials currently available. TiN is a gold-like ceramic with a permittivity cross-over near 500nm. In addition, TiN can attain ultra-thin, ultra-smooth epitaxial films on substrates such as c-sapphire, MgO, and silicon. Partnering TiN with CMOS compatible silicon nitride enables a fully solid state waveguide which is able to achieve a propagation length greater than 1cm for a ~8μm mode size at 1.55μm. Utilizing doped zinc oxide films as a dynamic material, high performance modulators can also be realized due to the low-loss achieved by the TiN/Si3N4 waveguide. Simply by placing a thin layer of aluminum doped zinc oxide (AZO) on top of the waveguide structure, a modulator with very low insertion loss is achieved. Our recent work has investigated optical tuning of AZO films by the pump-probe method, demonstrating a change in the refractive index of -0.17+0.25i at 1.3μm with an ultrafast response of 1ps. Assuming this change in the refractive index for the AZO film, a modulation of ~0.7dB/μm is possible in the structure with ~0.5dB insertion loss and an operational speed of 1THz. Further optimization of the design is expected to lead to an increased modulation depth without sacrificing insertion loss or speed. Consequently, nanophotonic technologies are reaching a critical point where many applications including telecom, medicine, and quantum science can see practical systems which provide new functionalities.

  9. The role of radiation transport in the thermal response of semitransparent materials to localized laser heating

    SciTech Connect

    Colvin, Jeffrey; Shestakov, Aleksei; Stolken, James; Vignes, Ryan

    2011-03-09

    Lasers are widely used to modify the internal structure of semitransparent materials for a wide variety of applications, including waveguide fabrication and laser glass damage healing. The gray diffusion approximation used in past models to describe radiation cooling is not adequate for these materials, particularly near the heated surface layer. In this paper we describe a computational model based upon solving the radiation transport equation in 1D by the Pn method with ~500 photon energy bands, and by multi-group radiationdiffusion in 2D with fourteen photon energy bands. The model accounts for the temperature-dependent absorption of infrared laser light and subsequent redistribution of the deposited heat by both radiation and conductive transport. We present representative results for fused silica irradiated with 2–12 W of 4.6 or 10.6 µm laser light for 5–10 s pulse durations in a 1 mm spot, which is small compared to the diameter and thickness of the silica slab. Furthermore, we show that, unlike the case for bulk heating, in localized infrared laser heatingradiation transport plays only a very small role in the thermal response of silica.

  10. Non-linear response in optical materials using ultra-short laser technology

    NASA Astrophysics Data System (ADS)

    Ashkenasi, David

    2007-02-01

    Ultra-short lasers at elevated peek powers combined with fairly moderate single pulse energies are able to induce very interesting non-linear optical interaction channels, such as multi-photon absorption, self-phase modulation and self focusing. These non-linear optical effects can be utilized to obtain surprising material reactions inside the bulk of optical dielectrics. With a certain degree of physical understanding and engineering experience, the material reaction can be controlled and optimized to generate e.g. internal markings, wave guides, 3d data storages or diffractive optical elements. As an example, laser-induced coloring of several type of glasses have been obtained at ultra-short bulk excitation, showing a strong resemblance to surface defects observed in most glasses after ionizing (e.g. X- and gamma-ray) hard radiation treatment. These laser-induced "color-centers" can alter the optical properties in dispersion and extinction locally in a well-defined volume, which can be described as a local change in the complex refractory index (n+ik). The implementation of this new technology can be characterized as "nik-engineering". New experimental results on laser-induced sub-surface modifications utilizing near infrared femtosecond and picosecond laser pulses inside different types of transparent dielectrics are presented and discussed in respect to the potential of "nik-engineering".

  11. Direct diode lasers and their advantages for materials processing and other applications

    NASA Astrophysics Data System (ADS)

    Fritsche, Haro; Ferrario, Fabio; Koch, Ralf; Kruschke, Bastian; Pahl, Ulrich; Pflueger, Silke; Grohe, Andreas; Gries, Wolfgang; Eibl, Florian; Kohl, Stefanie; Dobler, Michael

    2015-03-01

    The brightness of diode lasers is improving continuously and has recently started to approach the level of some solid state lasers. The main technology drivers over the last decade were improvements of the diode laser output power and divergence, enhanced optical stacking techniques and system design, and most recently dense spectral combining. Power densities at the work piece exceed 1 MW/cm2 with commercially available industrial focus optics. These power densities are sufficient for cutting and welding as well as ablation. Single emitter based diode laser systems further offer the advantage of fast current modulation due their lower drive current compared to diode bars. Direct diode lasers may not be able to compete with other technologies as fiber or CO2-lasers in terms of maximum power or beam quality. But diode lasers offer a range of features that are not possible to implement in a classical laser. We present an overview of those features that will make the direct diode laser a very valuable addition in the near future, especially for the materials processing market. As the brightness of diode lasers is constantly improving, BPP of less than 5mm*mrad have been reported with multikW output power. Especially single emitter-based diode lasers further offer the advantage of very fast current modulation due to their low drive current and therefore low drive voltage. State of the art diode drivers are already demonstrated with pulse durations of <10μs and repetition rates can be adjusted continuously from several kHz up to cw mode while addressing power levels from 0-100%. By combining trigger signals with analog modulations nearly any kind of pulse form can be realized. Diode lasers also offer a wide, adaptable range of wavelengths, and wavelength stabilization. We report a line width of less than 0.1nm while the wavelength stability is in the range of MHz which is comparable to solid state lasers. In terms of applications, especially our (broad) wavelength

  12. Briefing Materials for Technical Presentations, Volume A: The LACIE Symposium

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Tables, charts, and outlines of various segments within the Large Area Crop Inventory Experiment are presented. Experiment design, system implementation and operations, and data processing system design were considered.

  13. Microfabrication of transparent materials using filamented femtosecond laser beams

    NASA Astrophysics Data System (ADS)

    Butkus, S.; Paipulas, D.; Gaižauskas, Eugenijus; KaškelytÄ--, D.; Sirutkaitis, V.

    2014-05-01

    Glass drilling realized with the help of femtosecond lasers attract industrial attention, however, desired tasks may require systems employing high numerical aperture (NA) focusing conditions, low repetition rate lasers and complex fast motion translation stages. Due to the sensitivity of such systems, slight instabilities in parameter values can lead to crack formations, severe fabrication rate decrement and poor quality overall results. A microfabrication system lacking the stated disadvantages was constructed and demonstrated in this report. An f-theta lens was used in combination with a galvanometric scanner, in addition, a water pumping system that enables formation of water films of variable thickness in real time on the samples. Water acts as a medium for filament formation, which in turn decreases the focal spot diameter and increases fluence and axial focal length. This article demonstrates the application of a femtosecond (280fs) laser towards rapid cutting of different transparent materials. Filament formation in water gives rise to strong ablation at the surface of the sample, moreover, the water, surrounding the ablated area, adds increased cooling and protection from cracking. The constructed microfabrication system is capable of drilling holes in thick soda-lime, hardened glasses and sapphire. The fabrication time varies depending on the diameter of the hole and spans from a few to several hundred seconds. Moreover, complex-shape fabrication was demonstrated.

  14. Advances in micro/nano scale materials processing by ultrafast lasers

    NASA Astrophysics Data System (ADS)

    Fotakis, Costas

    2009-03-01

    Materials processing by ultrafast lasers offers several attractive possibilities for micro/nano scale applications based on surface and in bulk laser induced modifications. The origin of these applications lies in the reduction of undesirable thermal effects, the non-equilibrium surface and volume structural modifications which may give rise to complex and unusual structures, the supression of photochemical effects in molecular substrates, the possibility of optimization of energy dissipation by temporal pulse shaping and the exploitation of filamentation effects. Diverse applications will be discussed, including the development and functionalization of laser engineered surfaces, the laser transfer of biomolecules and the functionalization of 3D structures constructed by multiphoton stereolithography. Two examples will be presented in this context: A new approach for the development of superhydrophobic, self-cleaning surfaces [1,2] and the fabrication of functional scaffolds for tissue engineering applications [3-5]. [4pt] References: [0pt] [1] V. Zorba et al., ``Biomimetic artificial surfaces quantitatively reproduce the water repellency of a Lotus leaf'', Advanced Materials 20, 4049 (2008).[0pt] [2] V. Zorba et al., ``Tailoring the wetting response of silicon surfaces via fs laser structuring'', Applied Physics A 93, 819 (2008).[0pt] [3] V. Dinca et al., ``Quantification of the activity of biomolecules in microarrays obtained by direct laser transfer'', Biomedical Microdevices 10, 719 (2008).[0pt] [4] B. Hopp et al., ``Laser-based techniques for living cell pattern formation'', Applied Physics A 93, 45 (2008).[0pt] [5] V. Dinca et al., ``Directed three-dimensional patterning of self-assembled peptide fibrils'', Nano Letters 8, 538 (2008).

  15. Ultrafast Laser Diagnostics for Energetic-Material Ignition Mechanisms: Tools for Physics-Based Model Development.

    SciTech Connect

    Kearney, Sean Patrick; Jilek, Brook Anton; Kohl, Ian Thomas; Farrow, Darcie; Urayama, Junji

    2014-11-01

    We present the results of an LDRD project to develop diagnostics to perform fundamental measurements of material properties during shock compression of condensed phase materials at micron spatial scales and picosecond time scales. The report is structured into three main chapters, which each focus on a different diagnostic devel opment effort. Direct picosecond laser drive is used to introduce shock waves into thin films of energetic and inert materials. The resulting laser - driven shock properties are probed via Ultrafast Time Domain Interferometry (UTDI), which can additionally be used to generate shock Hugoniot data in tabletop experiments. Stimulated Raman scattering (SRS) is developed as a temperature diagnostic. A transient absorption spectroscopy setup has been developed to probe shock - induced changes during shock compressio n. UTDI results are presented under dynamic, direct - laser - drive conditions and shock Hugoniots are estimated for inert polystyrene samples and for the explosive hexanitroazobenzene, with results from both Sandia and Lawrence Livermore presented here. SRS a nd transient absorption diagnostics are demonstrated on static thin - film samples, and paths forward to dynamic experiments are presented.

  16. Laser-optical treatment for toothbrush bristles (nylon, synthetic, and polymeric materials, etc.)

    NASA Astrophysics Data System (ADS)

    Ma, Yangwu

    1994-08-01

    On the basis of the principle of laser radiation and materials interaction, a laser-optical treatment method for toothbrush bristles (nylon et al., synthetic and polymeric materials) is provided. In this process, laser irradiation is stopped during melting and followed by cooling, so the free end of each bristle of toothbrush is formed for a smooth globe. The toothbrush with laser-optical end-globed bristles have many remarkable functions.

  17. Quantum dots as active material for quantum cascade lasers: comparison to quantum wells

    NASA Astrophysics Data System (ADS)

    Michael, Stephan; Chow, Weng W.; Schneider, Hans Christian

    2016-03-01

    We review a microscopic laser theory for quantum dots as active material for quantum cascade lasers, in which carrier collisions are treated at the level of quantum kinetic equations. The computed characteristics of such a quantum-dot active material are compared to a state-of-the-art quantum-well quantum cascade laser. We find that the current requirement to achieve a comparable gain-length product is reduced compared to that of the quantum-well quantum cascade laser.

  18. Target Plate Material Influence on Fullerene-C60 Laser Desorption/Ionization Efficiency

    NASA Astrophysics Data System (ADS)

    Zeegers, Guido P.; Günthardt, Barbara F.; Zenobi, Renato

    2016-04-01

    Systematic laser desorption/ionization (LDI) experiments of fullerene-C60 on a wide range of target plate materials were conducted to gain insight into the initial ion formation in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The positive and negative ion signal intensities of precursor, fragment, and cluster ions were monitored, varying both the laser fluence (0-3.53 Jcm-2) and the ion extraction delay time (0-950 ns). The resulting species-specific ion signal intensities are an indication for the ionization mechanisms that contribute to LDI and the time frames in which they operate, providing insight in the (MA)LDI primary ionization. An increasing electrical resistivity of the target plate material increases the fullerene-C60 precursor and fragment anion signal intensity. Inconel 625 and Ti90/Al6/V4, both highly electrically resistive, provide the highest anion signal intensities, exceeding the cation signal intensity by a factor ~1.4 for the latter. We present a mechanism based on transient electrical field strength reduction to explain this trend. Fullerene-C60 cluster anion formation is negligible, which could be due to the high extraction potential. Cluster cations, however, are readily formed, although for high laser fluences, the preferred channel is formation of precursor and fragment cations. Ion signal intensity depends greatly on the choice of substrate material, and careful substrate selection could, therefore, allow for more sensitive (MA)LDI measurements.

  19. Surface roughness analysis after laser assisted machining of hard to cut materials

    NASA Astrophysics Data System (ADS)

    Przestacki, D.; Jankowiak, M.

    2014-03-01

    Metal matrix composites and Si3N4 ceramics are very attractive materials for various industry applications due to extremely high hardness and abrasive wear resistance. However because of these features they are problematic for the conventional turning process. The machining on a classic lathe still requires special polycrystalline diamond (PCD) or cubic boron nitride (CBN) cutting inserts which are very expensive. In the paper an experimental surface roughness analysis of laser assisted machining (LAM) for two tapes of hard-to-cut materials was presented. In LAM, the surface of work piece is heated directly by a laser beam in order to facilitate, the decohesion of material. Surface analysis concentrates on the influence of laser assisted machining on the surface quality of the silicon nitride ceramic Si3N4 and metal matrix composite (MMC). The effect of the laser assisted machining was compared to the conventional machining. The machining parameters influence on surface roughness parameters was also investigated. The 3D surface topographies were measured using optical surface profiler. The analysis of power spectrum density (PSD) roughness profile were analyzed.

  20. Picosecond pulsed laser processing of polycrystalline diamond and cubic boron nitride composite materials

    NASA Astrophysics Data System (ADS)

    Warhanek, Maximilian G.; Pfaff, Josquin; Meier, Linus; Walter, Christian; Wegener, Konrad

    2016-03-01

    Capabilities and advantages of laser ablation processes utilizing ultrashort pulses have been demonstrated in various applications of scientific and industrial nature. Of particular interest are applications that require high geometrical accuracy, excellent surface integrity and thus tolerate only a negligible heat-affected zone in the processed area. In this context, this work presents a detailed study of the ablation characteristics of common ultrahard composite materials utilized in the cutting tool industry, namely polycrystalline diamond (PCD) and polycrystalline cubic boron nitride composite (PCBN). Due to the high hardness of these materials, conventional mechanical processing is time consuming and costly. Herein, laser ablation is an appealing solution, since no process forces and no wear have to be taken into consideration. However, an industrially viable process requires a detailed understanding of the ablation characteristics of each material. Therefore, the influence of various process parameters on material removal and processing quality at 10 ps pulse duration are investigated for several PCD and PCBN grades. The main focus of this study examines the effect of different laser energy input distributions, such as pulse frequency and burst pulses, on the processing conditions in deep cutting kerfs and the resulting processing speed. Based on these results, recommendations for efficient processing of such materials are derived.

  1. Compartment syndrome presenting as ischemia following extravasation of contrast material

    PubMed Central

    Grand, Aaron; Yeager, Brian; Wollstein, Ronit

    2008-01-01

    A case of acute compartment syndrome of the forearm, resulting from contrast dye extravasation that presented as upper extremity ischemia, is described. Timely surgical intervention resulted in an excellent outcome. When extravasation of dye occurs, the patient should be evaluated for compartment syndrome despite the possible lack of typical symptoms. PMID:19721799

  2. Removal of dental filling materials by Er:YAG laser radiation

    NASA Astrophysics Data System (ADS)

    Hibst, Raimund; Keller, Ulrich

    1991-05-01

    In previous reports it could be shown that pulsed Er:YAG laser radiation is effective for the removal of dental enamel, dentin, and caries. Damage to the adjacent hard substances is minimal. Temperature measurements and animal studies revealed that thermal pulp damage can be avoided. The experimental results make the Er:YAG laser promising for the preparation of dental cavities. In many cases patients already have fillings which have to be removed. In the present work, investigation is made of the effect of Er:YAG laser radiation on various restorative filling materials. The experiments demonstrate that removal is possible for all tested cements, composites and amalgam. Ablation efficiency is comparable to that of enamel and dentin, and thus sufficient for practical applications. Morphology of crater walls indicates greater thermal side effects than for natural dental hard substances.

  3. Laser formation of Bragg gratings in polymer nanocomposite materials

    NASA Astrophysics Data System (ADS)

    Nazarov, M. M.; Khaydukov, K. V.; Sokolov, V. I.; Khaydukov, E. V.

    2016-01-01

    The method investigated in this work is based on the laser-induced, spatially inhomogeneous polymerisation of nanocomposite materials and allows control over the motion and structuring of nanoparticles. The mechanisms of nanoparticle concentration redistribution in the process of radical photopolymerisation are studied. It is shown that under the condition of spatially inhomogeneous illumination of a nanocomposite material, nanoparticles are diffused from the illuminated areas into the dark fields. Diffraction gratings with a thickness of 8 μm and a refractive index modulation of 1 × 10-2 are written in an OCM-2 monomer impregnated by silicon nanoparticles. The gratings may be used in the development of narrowband filters, in holographic information recording and as dispersion elements in integrated optical devices.

  4. Investigation of the electrical properties of some dental composite restorative materials before and after laser exposure.

    PubMed

    ElKestawy, M A; Saafan, S A; Shehata, M M; Saafan, A M

    2006-10-01

    Some electrical properties, such as piezoelectricity, ac conductivity, dielectric constant and loss tangent of nine commercial types of dental composite restorative materials, have been investigated before and after laser exposure for 3s to study the effect of a probable laser exposure during some surgeries on the electrical properties of these materials. No piezoelectric effect has been found in these materials before and after laser exposure. The materials were found to be good insulators (very poorly conducting materials). The temperature and frequency dependence of ac conductivity, dielectric constant and loss tangent have not shown significant changes in values after laser exposure.

  5. Mechanics of Composite Materials: Past, Present and Future

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.

    1984-01-01

    Composite mechanics disciplines are presented and described at their various levels of sophistication and attendant scales of application. Correlation with experimental data is used as the prime discriminator between alternative methods and level of sophistication. Major emphasis is placed on: (1) where composite mechanics has been; (2) what it has accomplished; (3) where it is headed, based on present research activities; and (4) at the risk of being presumptuous, where it should be headed. The discussion is developed using selected, but typical examples of each composite mechanics discipline identifying degree of success, with respect to correlation with experimental data, and problems remaining. The discussion is centered about fiber/resin composites drawn mainly from the author's research activities/experience spanning two decades at Lewis.

  6. Mechanics of composite materials - Past, present and future

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.

    1989-01-01

    Composite mechanics disciplines are presented and described at their various levels of sophistication and attendant scales of application. Correlation with experimental data is used as the prime discriminator between alternative methods and level of sophistication. Major emphasis is placed on: (1) where composite mechanics has been; (2) what it has accomplished; (3) where it is headed, based on present research activities; and (4) at the risk of being presumptuous, where it should be headed. The discussion is developed using selected, but typical examples of each composite mechanics discipline identifying degree of success, with respect to correlation with experimental data, and problems remaining. The discussion is centered about fiber/resin composites drawn mainly from the author's research activities/experience spanning two decades at Lewis.

  7. Nano-material size dependent laser-plasma thresholds

    NASA Astrophysics Data System (ADS)

    EL Sherbini, Ashraf M.; Parigger, Christian G.

    2016-10-01

    The reduction of laser fluence for initiation of plasma was measured for zinc monoxide nanoparticles of diameters in the range of 100 to 20 nm. In a previous work by EL Sherbini and Parigger [Wavelength Dependency and Threshold Measurements for Nanoparticle-enhanced Laser-induced Breakdown Spectroscopy, Spectrochim. Acta Part B 116 (2016) 8-15], the hypothesis of threshold dependence on particle size leads to the interpretation of the experiments for varying excitation wavelengths with fixed, 30 nm nanomaterial. The experimental results presented in this work were obtained with 1064 nm Nd:YAG radiation and confirm and validate the suspected reduction due to quenching of the thermal conduction length to the respective sizes of the nanoparticles.

  8. High power laser heating of low absorption materials

    SciTech Connect

    Olson, K.; Talghader, J.; Ogloza, A.; Thomas, J.

    2014-09-28

    A model is presented and confirmed experimentally that explains the anomalous behavior observed in continuous wave (CW) excitation of thermally isolated optics. Distributed Bragg Reflector (DBR) high reflective optical thin film coatings of HfO₂ and SiO₂were prepared with a very low absorption, about 7 ppm, measured by photothermal common-path interferometry. When illuminated with a 17 kW CW laser for 30 s, the coatings survived peak irradiances of 13 MW/cm², on 500 μm diameter spot cross sections. The temperature profile of the optical surfaces was measured using a calibrated thermal imaging camera for illuminated spot sizes ranging from 500 μm to 5 mm; about the same peak temperatures were recorded regardless of spot size. This phenomenon is explained by solving the heat equation for an optic of finite dimensions and taking into account the non-idealities of the experiment. An analytical result is also derived showing the relationship between millisecond pulse to CW laser operation where (1) the heating is proportional to the laser irradiance (W/m²) for millisecond pulses, (2) the heating is proportional to the beam radius (W/m) for CW, and (3) the heating is proportional to W/m∙ tan⁻¹(√(t)/m) in the transition region between the two.

  9. Laser vibrometry for investigation of tympanic membrane implant materials

    NASA Astrophysics Data System (ADS)

    Zahnert, Thomas; Kuster, Manfred; Vogel, Uwe; Hofmann, Gert; Huettenbrink, Karl-Bernd

    1996-12-01

    The human tympanic membrane has reasonably good sound sensing properties. A destroyed tympanic membrane due to middle ear diseases or traumata may be repaired by different types of grafts. Middle ear surgery mostly uses autologous temporal fascia, cartilage, or cartilage perichondrium transplants. We have investigated the acoustical and mechanical properties of these materials and compared them with human tympanic membrane by constructing an ear canal model completed by an artificial tympanic membrane. Circular stretched human fascia, perichondrium, and cartilage preparations were exposed to static pressures up to 4 kPa and white noise sound pressure levels of 70 dB. The vibrational amplitudes and displacements due to static pressure of the graft material were measured by laser Doppler vibrometry and compared. The thin materials temporal fascia and perichondrium show similar amplitude frequency responses compared to the tympanic membrane for dynamic excitation. The displacement of these materials at static pressures above 4 kPA yields a higher compliance than tympanic membrane. The acoustical and mechanical properties of cartilage transplants change with the thickness of the slices. However, the thinner the cartilage slice combined with lower stability, the more similar is the frequency response with the intact tympanic membrane. The vibration amplitudes decrease more and more for layer thicknesses above 500 micrometers. Cartilage acts as an excellent transplant material which provides a better prognosis than different materials in cases of ventilation disorders with long-term middle ear pressure changes. Large cartilage slice transplants should not exceed layer thicknesses of 500 micrometer in order to prevent drawbacks to the transfer characteristics of the tympanic membrane.

  10. Dissimilar material joining using laser (aluminum to steel using zinc-based filler wire)

    NASA Astrophysics Data System (ADS)

    Mathieu, Alexandre; Shabadi, Rajashekar; Deschamps, Alexis; Suery, Michel; Matteï, Simone; Grevey, Dominique; Cicala, Eugen

    2007-04-01

    Joining steel with aluminum involving the fusion of one or both materials is possible by laser beam welding technique. This paper describes a method, called laser braze welding, which is a suitable process to realize this structure. The main problem with thermal joining of steel/aluminum assembly with processes such as TIG or MIG is the formation of fragile intermetallic phases, which are detrimental to the mechanical performances of such joints. Braze welding permits a localized fusion of the materials resulting in a limitation on the growth of fragile phases. This article presents the results of a statistical approach for an overlap assembly configuration using a filler wire composed of 85% Zn and 15% Al. Tensile tests carried on these assemblies demonstrate a good performance of the joints. The fracture mechanisms of the joints are analyzed by a detailed characterization of the seams.

  11. Material processing with ultra-short pulse lasers working in 2μm wavelength range

    NASA Astrophysics Data System (ADS)

    Voisiat, B.; Gaponov, D.; Gečys, P.; Lavoute, L.; Silva, M.; Hideur, A.; Ducros, N.; Račiukaitis, G.

    2015-03-01

    New wavelengths of laser radiation are of interest for material processing. Results of application of the all-fiber ultrashort pulsed laser emitting in 2 µm range, manufactured by Novae, are presented. Average output power was 4.35 W in a single-spatial-mode beam centered at the 1950 nm wavelength. Pulses duration was 40 ps, and laser operated at 4.2 MHz pulse repetition rate. This performance corresponded to 25 kW of pulse peak power and almost 1 µJ in pulse energy. Material processing was performed using three different focusing lenses (100, 30 and 18 mm) and mechanical stages for the workpiece translation. 2 µm laser radiation is strongly absorbed by some polymers. Swelling of PMMA surface was observed for scanning speed above 5 mm/s using the average power of 3.45 W focused with the 30 mm lens. When scanning speed was reduced below 4 mm/s, ablation of PMMA took place. The swelling of PMMA is a consequence of its melting due to absorbed laser power. Therefore, experiments on butt welding of PMMA and overlapping welding of PMMA with other polymers were performed. Stable joint was achieved for the butt welding of two PMMA blocks with thickness of 5 mm. The laser was used to cut a Kapton film on a paper carrier with the same set-up as previous. The cut width depended on the cutting speed and focusing optics. A perfect cut with a width of 11 µm was achieved at the translation speed of 60 mm/s.

  12. Characterization of material ablation driven by laser generated intense extreme ultraviolet light

    SciTech Connect

    Tanaka, Nozomi Masuda, Masaya; Deguchi, Ryo; Murakami, Masakatsu; Fujioka, Shinsuke; Yogo, Akifumi; Nishimura, Hiroaki; Sunahara, Atsushi

    2015-09-14

    We present a comparative study on the hydrodynamic behaviour of plasmas generated by material ablation by the irradiation of nanosecond extreme ultraviolet (EUV or XUV) or infrared laser pulses on solid samples. It was clarified that the difference in the photon energy deposition and following material heating mechanism between these two lights result in the difference in the plasma parameters and plasma expansion characteristics. Silicon plate was ablated by either focused intense EUV pulse (λ = 9–25 nm, 10 ns) or laser pulse (λ = 1064 nm, 10 ns), both with an intensity of ∼10{sup 9 }W/cm{sup 2}. Both the angular distributions and energy spectra of the expanding ions revealed that the photoionized plasma generated by the EUV light differs significantly from that produced by the laser. The laser-generated plasma undergoes spherical expansion, whereas the EUV-generated plasma undergoes planar expansion in a comparatively narrow angular range. It is presumed that the EUV radiation is transmitted through the expanding plasma and directly photoionizes the samples in the solid phase, consequently forming a high-density and high-pressure plasma. Due to a steep pressure gradient along the direction of the target normal, the EUV plasma expands straightforward resulting in the narrower angular distribution observed.

  13. Numerical modeling of pulsed laser-material interaction and of laser plume dynamics

    SciTech Connect

    Zhao, Qiang; Shi, Yina

    2015-03-10

    We have developed two-dimensional Arbitrary Lagrangian Eulerian (ALE) code which is used to study the physical processes, the plasma absorption, the crater profile, and the temperature distribution on metallic target and below the surface. The ALE method overcomes problems with Lagrangian moving mesh distortion by mesh smoothing and conservative quantities remapping from Lagrangian mesh to smoothed one. A new second order accurate diffusion solver has been implemented for the thermal conduction and radiation transport on distorted mesh. The results of numerical simulation of pulsed laser ablation are presented. The influences of different processes, such as time evolution of the surface temperature, interspecies interactions (elastic collisions, recombination-dissociation reaction), interaction with an ambient gas are examined. The study presents particular interest for the analysis of experimental results obtained during pulsed laser ablation.

  14. Wavelength dependence of femtosecond laser-induced damage threshold of optical materials

    SciTech Connect

    Gallais, L. Douti, D.-B.; Commandré, M.; Batavičiūtė, G.; Pupka, E.; Ščiuka, M.; Smalakys, L.; Sirutkaitis, V.; Melninkaitis, A.

    2015-06-14

    An experimental and numerical study of the laser-induced damage of the surface of optical material in the femtosecond regime is presented. The objective of this work is to investigate the different processes involved as a function of the ratio of photon to bandgap energies and compare the results to models based on nonlinear ionization processes. Experimentally, the laser-induced damage threshold of optical materials has been studied in a range of wavelengths from 1030 nm (1.2 eV) to 310 nm (4 eV) with pulse durations of 100 fs with the use of an optical parametric amplifier system. Semi-conductors and dielectrics materials, in bulk or thin film forms, in a range of bandgap from 1 to 10 eV have been tested in order to investigate the scaling of the femtosecond laser damage threshold with the bandgap and photon energy. A model based on the Keldysh photo-ionization theory and the description of impact ionization by a multiple-rate-equation system is used to explain the dependence of laser-breakdown with the photon energy. The calculated damage fluence threshold is found to be consistent with experimental results. From these results, the relative importance of the ionization processes can be derived depending on material properties and irradiation conditions. Moreover, the observed damage morphologies can be described within the framework of the model by taking into account the dynamics of energy deposition with one dimensional propagation simulations in the excited material and thermodynamical considerations.

  15. Dual-beam laser thermal processing of silicon photovoltaic materials

    NASA Astrophysics Data System (ADS)

    Simonds, Brian J.; Teal, Anthony; Zhang, Tian; Hadler, Josh; Zhou, Zibo; Varlamov, Sergey; Perez-Würfl, Ivan

    2016-03-01

    We have developed an all-laser processing technique by means of two industrially-relevant continuous-wave fiber lasers operating at 1070 nm. This approach is capable of both substrate heating with a large defocused beam and material processing with a second scanned beam, and is suitable for a variety of photovoltaic applications. We have demonstrated this technique for rapid crystallization of thin film (~10 μm) silicon on glass, which is a low cost alternative to wafer-based solar cells. We have also applied this technique to wafer silicon to control dopant diffusion at the surface region where the focused line beam rapidly melts the substrate that then regrows epitaxially. Finite element simulations have been used to model the melt depth as a function of preheat temperature and line beam power. This process is carried out in tens of seconds for an area approximately 10 cm2 using only about 1 kW of total optical power and is readily scalable. In this paper, we will discuss our results with both c-Si wafers and thin-film silicon.

  16. Results of UV laser application on biological material

    NASA Astrophysics Data System (ADS)

    Alifano, P.; Nassisi, Vincenzo; Pompa, Pier P.; Candido, A.

    2002-08-01

    In this paper we report on the biological effects of XeCL laser irradiation on Staphylococcus epidermidis and Escherichia coli. UV interaction with cellular systems is responsible for photochemical, photothermal or photodecomposition processes. When short-wavelength UV radiation strikes biological material, the DNA is damaged causing cell killing, mutagenesis or carcinogenesis. We report on different effects of XeCl laser irradiation on two microbial systems; collection strain of Staphylococcus epidermidis (in suspension) and collection strains of Eschericha coli proficient or deficient in DNA recombination/repair pathways (irradiated on solid surfaces). In S epidermidis the 308 nm radiation can significantly enhanced the proliferation rates. In wild type E. coli cells the radiation did not stimulate the growth rates. Surprisingly, the 308 nm radiation elicited a very strong lethal effect on DNA recombination/repair-defective strains (harbouring the recA56 null mutation), even more pronounced than irradiation with a UV 254 nm germicidal lamp. The unknown mechanism responsible for this biological response is currently under investigation.

  17. Ion Acceleration by Laser Plasma Interaction from Cryogenic Micro Jets - Oral Presentation

    SciTech Connect

    Propp, Adrienne

    2015-08-25

    possibility of transforming our liquid cryogenic jets into droplet streams. This type of target should solve our problems with the jet as it will prevent the flow of exocurrent into the nozzle. It is also highly effective as it is even more mass-limited than standard cryogenic jets. Furthermore, jets break up spontaneously anyway. If we can control the breakup, we can synchronize the droplet emission with the laser pulses. In order to assist the team prepare for an experiment later this year, I familiarized myself with the physics and theory of droplet formation, calculated values for the required parameters, and ordered the required materials for modification of the jet. Future experiments will test these droplet streams and continue towards the goal of ion acceleration using cryogenic targets.

  18. Material properties identification using ultrasonic waves and laser Doppler vibrometer measurements: a multi-input multi-output approach

    NASA Astrophysics Data System (ADS)

    Longo, R.; Vanlanduit, S.; Guillaume, P.

    2013-10-01

    In this paper a multi-input multi-output approach able to determine the material properties of homogeneous materials is presented. To do so, an experimental set-up which combines the use of multi harmonic signals with interleaved frequencies and laser Doppler vibrometer measurements has been developed. A modeling technique, based on transmission and reflection measurements, allowed the simultaneous determination of longitudinal wave velocity, density and thickness of the materials under test with high levels of precision and accuracy.

  19. Laser-Induced Damage in Optical Materials: 2005, Proceedings of SPIE,

    SciTech Connect

    Exarhos, Gregory J.; Guenther, Arthur H.; Ristau, Detlev; Lewis, Keith L.; Soileau, M. J.; Stolz, Christopher J.

    2005-12-27

    This volume contains papers presented at the 37th Annual Symposium on Optical Materials for High-Power Lasers that was held at the National Institute of Standards and Technology in Boulder, Colorado, 19-21 September 2005. The symposium was cosponsored by Lawrence Livermore National Laboratory (USA), and the Pacific Northwest National Laboratory (USA). Cooperating organizations were the Center for High Technology Materials at the University of New Mexico (USA), Laser Zentrum Hannover e.V. (Germany), the National Institute of Standards and Technology (USA), QinetiQ (United Kingdom), and the College of Optics and Photonics, CREOL and FPCE, University of Central Florida (USA). The symposium, was attended by 145 scientist and engineers from China, France, Lithuania, Russia, France, Germany, Japan, the Netherlands, Russia, the United States, and the United Kingdom. One-third of the attendees and nearly half of the presentations were from abroad. A mini-symposium on Tuesday afternoon, that addressed damage issues associated with petawatt lasers, highlighted our growing interest in the emerging area. Including the mini-symposium, 87 papers were presented in oral and poster sessions.

  20. High-energy density experiments on planetary materials using high-power lasers and X-ray free electron laser

    NASA Astrophysics Data System (ADS)

    Ozaki, Norimasa

    2015-06-01

    Laser-driven dynamic compression allows us to investigate the behavior of planetary and exoplanetary materials at extreme conditions. Our high-energy density (HED) experiments for applications to planetary sciences began over five years ago. We measured the equation-of-state of cryogenic liquid hydrogen under laser-shock compression up to 55 GPa. Since then, various materials constituting the icy giant planets and the Earth-like planets have been studied using laser-driven dynamic compression techniques. Pressure-volume-temperature EOS data and optical property data of water and molecular mixtures were obtained at the planetary/exoplanetary interior conditions. Silicates and oxides data show interesting behaviors in the warm-dense matter regime due to their phase transformations. Most recently the structural changes of iron were observed for understanding the kinetics under the bcc-hcp transformation phenomena on a new HED science platform coupling power-lasers and the X-ray free electron laser (SACLA). This work was performed under the joint research project at the Institute of Laser Engineering, Osaka University. It was partially supported by a Grant-in-Aid for Scientific Research (Grant Nos. 20654042, 22224012, 23540556, and 24103507) and also by grants from the Core-to-Core Program of JSPS on International Alliance for Material Science in Extreme States with High Power Laser and XFEL, and the X-ray Free Electron Laser Priority Strategy Program of MEXT.

  1. Laser-launched flyer plates and direct laser shocks for dynamic material property measurements

    NASA Astrophysics Data System (ADS)

    Paisley, Dennis; Swift, Damian; Johnson, Randall; Kopp, Roger; Kyrala, George

    2001-06-01

    The Trident laser at Los Alamos was used to impart known and controlled shocks in various materials by launching flyer plates or by irradiating the sample directly. Materials investigated include copper, gold, NiTi, SS316, and other metals and alloys. Tensile spall strength, elastic-plastic transition, phase boundaries, and equation of state can be determined with small samples. Using thin samples (0.1 - 1.0 mm thick) as targets, high pressure gradients can be generated with relatively low pressures, resulting in high tensile strain rates (10^5 to 10^8 s-1). Free surface and interface velocities are recorded with point- and line-imaging VISARs. The flexible spatial and temporal pulse profiles of Trident, coupled with the use of laser-launched flyer plates, provides capabilities which complement experiments conducted using gas guns and tensile bars. These samples spalled at high strain rates will be compared with samples spalled at lower strain rates to elucidate mechanisms for the initiation and growth of spall.

  2. Femtosecond laser fabricated integrated chip for manipulation of single cells (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Keloth, Anusha; Jimenez, Melanie; Bridle, H.; Paterson, Lynn; Markx, Gerard H.; Kar, Ajoy K.

    2016-03-01

    Optical micromanipulation techniques and microfluidic techniques can be used in same platform for manipulating biological samples at single cell level. Novel microfluidic devices with integrated channels and waveguides fabricated using ultrafast laser inscription combined with selective chemical etching can be used to enable sorting and isolation of biological cells. In this paper we report the design and fabrication of a three dimensional chip that can be used to manipulate single cells in principle with a higher throughput than is possible using optical tweezers. The capability of ultrafast laser inscription followed by selective chemical etching to fabricate microstructures and waveguides have been utilised to fabricate the device presented in this paper. The complex three dimensional microfluidic structures within the device allow the injected cell population to focus in a hydrodynamic flow. A 1064 nm cw laser source, coupled to the integrated waveguide, is used to exert radiation pressure on the cells to be manipulated. As the cells in the focussed stream flow past the waveguide, optical scattering force induced by the laser beam pushes the cell from out of the focussed stream to the sheath fluid, which can be then collected at the outlet. Thus cells can be controllably deflected from the focussed flow to the side channel for downstream analysis or culture.

  3. Laser-assisted cavity preparation and adhesion to erbium-lased tooth structure: part 2. present-day adhesion to erbium-lased tooth structure in permanent teeth.

    PubMed

    De Moor, Roeland Jozef Gentil; Delme, Katleen Ilse Maria

    2010-04-01

    With the introduction of the Er:YAG laser, it has become possible to remove enamel and dentin more effectively and efficiently than with other lasers. Thermal damage is reduced, especially in conjunction with water spray. Since FDA (Federal Drug Administration) approval of the Er:YAG laser in 1997--for caries removal, cavity preparation and conditioning of tooth substance - there have been many reports on the use of this technique in combination with composite resins. Moreover, cavity pretreatment with Er:YAG laser (laser etching) has been proposed as an alternative to acid etching of enamel and dentin. Reports evaluating the adhesion of glass-ionomer cements to Er:YAG-lased tooth substance are scarce. This article reviews the literature regarding adhesion and sealing efficacy using different (pre)treatment protocols in association with Er:YAG laser preparation. Recent research has shown that lasing of enamel and dentin may result in surface and subsurface alterations that have negative effects on both adhesion and seal. It is concluded that at present, it is advisable to respect the conventional pretreatment procedures as needed for the respective adhesive materials. Although the majority of present day reports show that microleakage and bond strength are negatively influenced by laser (pre)treatment (compared with conventional preparation), there is ongoing discussion of how adhesion is best achieved on Er:YAG-lased surfaces.

  4. Real-time measurement of materials properties at high temperatures by laser produced plasmas

    NASA Technical Reports Server (NTRS)

    Kim, Yong W.

    1990-01-01

    Determination of elemental composition and thermophysical properties of materials at high temperatures, as visualized in the context of containerless materials processing in a microgravity environment, presents a variety of unusual requirements owing to the thermal hazards and interferences from electromagnetic control fields. In addition, such information is intended for process control applications and thus the measurements must be real time in nature. A new technique is described which was developed for real time, in-situ determination of the elemental composition of molten metallic alloys such as specialty steel. The technique is based on time-resolved spectroscopy of a laser produced plasma (LPP) plume resulting from the interaction of a giant laser pulse with a material target. The sensitivity and precision were demonstrated to be comparable to, or better than, the conventional methods of analysis which are applicable only to post-mortem specimens sampled from a molten metal pool. The LPP technique can be applied widely to other materials composition analysis applications. The LPP technique is extremely information rich and therefore provides opportunities for extracting other physical properties in addition to the materials composition. The case in point is that it is possible to determine thermophysical properties of the target materials at high temperatures by monitoring generation and transport of acoustic pulses as well as a number of other fluid-dynamic processes triggered by the LPP event. By manipulation of the scaling properties of the laser-matter interaction, many different kinds of flow events, ranging from shock waves to surface waves to flow induced instabilities, can be generated in a controllable manner. Time-resolved detection of these events can lead to such thermophysical quantities as volume and shear viscosities, thermal conductivity, specific heat, mass density, and others.

  5. Computational modelling of Er(3+): Garnet laser materials

    NASA Technical Reports Server (NTRS)

    Spangler, Lee H.

    1994-01-01

    The Er(3+) ion has attracted a lot of interest for four reasons: (1) Its (4)I(sub 13/2) yields (4)I(sub 15/2) transition lases in the eyesafe region near 1.5 micron; (2) the (4)I(sub 13/2) transition lases near 2.8 micron, an important wavelength for surgical purposes; (3) it displays surprisingly efficient upconversion with lasing observed at 1.7, 1.2, 0.85, 0.56, 0.55, and 0.47 micron following 1.5 micron pumping; and (4) it has absorption bands at 0.96 and 0.81 micron and thus can be diode pumped. However, properties desirable for upconversion reduce the efficiency of 1.5 and 3 micron laser operation and vice versa. Since all of the processes are influenced by the host via the crystal field induced stark splittings in the Er levels, this project undertook modelling of the host influence on the Er lasinng behavior. While growth and measurement of all ten Er(3+) doped garnets is the surest way of identifying hosts which maximize upconversion (or conversly, 1.5 and 3 micron performance), it is also expensive - costing approximately $10,000/material or approximately $100,000 for the materials computationally investigated here. The calculations were performed using a quantum mechanical point charge model developed by Clyde Morrison at Harry Diamond Laboratories. The programs were used to fit the Er:YAG experimental energy levels so that the crystal field parameters, B(sub nm) could be extracted. From these radial factors, rho (sub n) were determined for Er(3+) in garnets. These, in combination with crystal field components, Anm, available from X-ray data, were used to predict energy levels for Er in the other nine garnet hosts. The levels in Er:YAG were fit with an rms error of 12.2/cm over a 22,000/cm range. Predicted levels for two other garnets for which literature values were available had rms errors of less than 17/cm , showing the calculations to be reliable. Based on resonances between pairs of calculated stark levels, the model predicts GSGG as the best host

  6. Permanent laser conditioning of thin film optical materials

    DOEpatents

    Wolfe, C.R.; Kozlowski, M.R.; Campbell, J.H.; Staggs, M.; Rainer, F.

    1995-12-05

    The invention comprises a method for producing optical thin films with a high laser damage threshold and the resulting thin films. The laser damage threshold of the thin films is permanently increased by irradiating the thin films with a fluence below an unconditioned laser damage threshold. 9 figs.

  7. Permanent laser conditioning of thin film optical materials

    DOEpatents

    Wolfe, C. Robert; Kozlowski, Mark R.; Campbell, John H.; Staggs, Michael; Rainer, Frank

    1995-01-01

    The invention comprises a method for producing optical thin films with a high laser damage threshold and the resulting thin films. The laser damage threshold of the thin films is permanently increased by irradiating the thin films with a fluence below an unconditioned laser damage threshold.

  8. Direct laser writing of three-dimensional network structures as templates for disordered photonic materials

    NASA Astrophysics Data System (ADS)

    Haberko, Jakub; Muller, Nicolas; Scheffold, Frank

    2013-10-01

    In the present article we substantially expand on our recent study about the fabrication of mesoscale polymeric templates of disordered photonic network materials [Haberko and Scheffold, Opt. Expr.OPEXFF1094-408710.1364/OE.21.001057 21, 1057 (2013)]. We present a detailed analysis and discussion of important technical aspects related to the fabrication and characterization of these fascinating materials. Compared to our initial report we were able to reduce the typical structural length scale of the seed pattern from a=3.3μm to a=2μm, bringing it closer to the technologically relevant fiber-optic communications wavelength range around λ˜1.5μm. We have employed scanning electron microscopy coupled with focused ion beam cutting to look inside the bulk of the samples of different heights. Moreover, we demonstrate the use of laser scanning confocal microscopy to assess the real space structure of the samples fabricated by direct laser writing. We address in detail questions about scalability, finite size effects, and geometrical distortions. We also study the effect of the lithographic voxel shape, that is, the ellipsoidal shape of the laser pen used in the fabrication process. To this end we employ detailed numerical modeling of the scattering function using a discrete dipole approximation scheme.

  9. High shock release in ultrafast laser irradiated metals: Scenario for material ejection

    NASA Astrophysics Data System (ADS)

    Colombier, J. P.; Combis, P.; Stoian, R.; Audouard, E.

    2007-03-01

    We present one-dimensional numerical simulations describing the behavior of solid matter exposed to subpicosecond near infrared pulsed laser radiation. We point out to the role of strong isochoric heating as a mechanism for producing highly nonequilibrium thermodynamic states. In the case of metals, the conditions of material ejection from the surface are discussed in a hydrodynamic context, allowing correlation of the thermodynamic features with ablation mechanisms. A convenient synthetic representation of the thermodynamic processes is presented, emphasizing different competitive pathways of material ejection. Based on the study of the relaxation and cooling processes which constrain the system to follow original thermodynamic paths, we establish that the metal surface can exhibit several kinds of phase evolution which can result in phase explosion or fragmentation. An estimation of the amount of material exceeding the specific energy required for melting is reported for copper and aluminum and a theoretical value of the limit size of the recast material after ultrashort laser irradiation is determined. Ablation by mechanical fragmentation is also analyzed and compared to experimental data for aluminum subjected to high tensile pressures and ultrafast loading rates. Spallation is expected to occur at the rear surface of the aluminum foils and a comparison with simulation results can determine a spall strength value related to high strain rates.

  10. Generation of shock waves and formation of craters in a solid material irradiated by a short laser pulse

    SciTech Connect

    Gus'kov, Sergei Yu; Borodziuk, S; Kasperczuk, A; Pisarczyk, T; Kalal, M; Limpouch, J; Kralikova, B; Krousky, E; Masek, K; Pfeifer, M; Rohlena, K; Skala, J; Ullschmied, J; Pisarczyk, P

    2004-11-30

    The results of investigations are presented which are concerned with laser radiation absorption in a target, the plasma state of its ablated material, the energy transfer to the solid target material, the characteristics of the shock wave and craters on the target surface. The investigation involved irradiation of a planar target by a subnanosecond plasma-producing laser pulse. The experiments were carried out with massive aluminium targets using the PALS iodine laser, whose pulse duration (0.4 ns) was much shorter than the shock wave attenuation and on-target crater formation times (50-200 ns). The investigations were conducted for a laser radiation energy of 100 J at two wavelengths of 0.438 and 1.315 {mu}m. For a given pulse energy, the irradiation intensity was varied in a broad range (10{sup 13}-10{sup 16} W cm{sup -2}) by varying the radius of the laser beam. The efficiency of laser radiation-to-shock energy transfer was determined as a function of the intensity and wavelength of laser radiation; also determined were the characteristics of the plasma plume and the shock wave propagating in the solid target, including the experimental conditions under which two-dimensional effects are highly significant. (invited paper)

  11. Seam tracking with texture based image processing for laser materials processing

    NASA Astrophysics Data System (ADS)

    Krämer, S.; Fiedler, W.; Drenker, A.; Abels, P.

    2014-02-01

    This presentation deals with a camera based seam tracking system for laser materials processing. The digital high speed camera records interaction point and illuminated work piece surface. The camera system is coaxially integrated into the laser beam path. The aim is to observe interaction point and joint gap in one image for a closed loop control of the welding process. Especially for the joint gap observation a new image processing method is used. Basic idea is to detect a difference between the textures of the surface of the two work pieces to be welded together instead of looking for a nearly invisible narrow line imaged by the joint gap. The texture based analysis of the work piece surface is more robust and less affected by varying illumination conditions than conventional grey scale image processing. This technique of image processing gives in some cases the opportunity for real zero gap seam tracking. In a condensed view economic benefits are simultaneous laser and seam tracking for self-calibrating laser welding applications without special seam pre preparation for seam tracking.

  12. Uniform heating of materials into the warm dense matter regime with laser-driven quasimonoenergetic ion beams

    SciTech Connect

    Bang, W.; Albright, B. J.; Bradley, P. A.; Vold, E. L.; Boettger, J. C.; Fernández, J. C.

    2015-12-01

    In a recent experiment at the Trident laser facility, a laser-driven beam of quasimonoenergetic aluminum ions was used to heat solid gold and diamond foils isochorically to 5.5 and 1.7 eV, respectively. Here theoretical calculations are presented that suggest the gold and diamond were heated uniformly by these laser-driven ion beams. According to calculations and SESAME equation-of-state tables, laser-driven aluminum ion beams achievable at Trident, with a finite energy spread of ΔE/E~20%, are expected to heat the targets more uniformly than a beam of 140-MeV aluminum ions with zero energy spread. As a result, the robustness of the expected heating uniformity relative to the changes in the incident ion energy spectra is evaluated, and expected plasma temperatures of various target materials achievable with the current experimental platform are presented.

  13. Uniform heating of materials into the warm dense matter regime with laser-driven quasimonoenergetic ion beams

    DOE PAGES

    Bang, W.; Albright, B. J.; Bradley, P. A.; Vold, E. L.; Boettger, J. C.; Fernández, J. C.

    2015-12-01

    In a recent experiment at the Trident laser facility, a laser-driven beam of quasimonoenergetic aluminum ions was used to heat solid gold and diamond foils isochorically to 5.5 and 1.7 eV, respectively. Here theoretical calculations are presented that suggest the gold and diamond were heated uniformly by these laser-driven ion beams. According to calculations and SESAME equation-of-state tables, laser-driven aluminum ion beams achievable at Trident, with a finite energy spread of ΔE/E~20%, are expected to heat the targets more uniformly than a beam of 140-MeV aluminum ions with zero energy spread. As a result, the robustness of the expected heatingmore » uniformity relative to the changes in the incident ion energy spectra is evaluated, and expected plasma temperatures of various target materials achievable with the current experimental platform are presented.« less

  14. Toward IFE Oriented Laser Chains: Cryogenically Cooled Ytterbium Doped Materials

    SciTech Connect

    Bourdet, G.; Casagrande, O.; Cardinali, V.; Deguil-Robin, N.; Le Garrec, B.

    2009-09-27

    With the aim to set up Inertial Fusion Energy (IFE) driver, we develop the properties of the Ytterbium doped materials and the problems met when designing such a system: essentially thermal management and ASE gain depletion. We after present the experimental results obtained using sesquioxide Yb{sup 3+} doped ceramics at cryogenic temperature. We also propose a solution for minimizing the ASE problem.

  15. Selective laser sintering of calcium phosphate materials for orthopedic implants

    NASA Astrophysics Data System (ADS)

    Lee, Goonhee

    Two technologies, Solid Freeform Fabrication (SFF) and bioceramics are combined in this work to prepare bone replacement implants with complex geometry. SFF has emerged as a crucial technique for rapid prototyping in the last decade. Selective Laser Sintering (SLS) is one of the established SFF manufacturing processes that can build three-dimensional objects directly from computer models without part-specific tooling or human intervention. Meanwhile, there have been great efforts to develop implantable materials that can assist in regeneration of bone defects and injuries. However, little attention has been focused in shaping bones from these materials. The main thrust of this research was to develop a process that can combine those two separate efforts. The specific objective of this research is to develop a process that can construct bone replacement material of complex geometry from synthetic calcium phosphate materials by using the SLS process. The achievement of this goal can have a significant impact on the quality of health care in the sense that complete custom-fit bone and tooth structures suitable for implantation can be prepared within 24--48 hours of receipt of geometric information obtained either from patient Computed Tomographic (CT) data, from Computer Aided Design (CAD) software or from other imaging systems such as Magnetic Resonance Imaging (MRI) and Holographic Laser Range Imaging (HLRI). In this research, two different processes have been developed. First is the SLS fabrication of porous bone implants. In this effort, systematic procedures have been established and calcium phosphate implants were successfully fabricated from various sources of geometric information. These efforts include material selection and preparation, SLS process parameter optimization, and development of post-processing techniques within the 48-hour time frame. Post-processing allows accurate control of geometry and of the chemistry of calcium phosphate, as well as

  16. Research and application of surface heat treatment for multipulse laser ablation of materials

    NASA Astrophysics Data System (ADS)

    Cai, Song; Chen, Genyu; Zhou, Cong

    2015-11-01

    This study analysed a laser ablation platform and built heat transfer equations for multipulse laser ablation of materials. The equations include three parts: laser emission after the material melt and gasification; end of laser emission after the material melts and there is the presence of a super-hot layer and solid-phase heat transfer changes during material ablation. For each of the three parts, the effects of evaporation, plasma shielding and energy accumulation under the pulse interval were considered. The equations are reasonable, and all the required parameters are only related to the laser parameters and material properties, allowing the model to have a certain versatility and practicability. The model was applied for numerical simulation of the heat transfer characteristics in the multipulse laser ablation of bronze and diamond. Next, experiments were conducted to analyse the topography of a bronze-bonded diamond grinding wheel after multipulse laser ablation. The theoretical analysis and experimental results showed that multipulse laser can merge the truing and dressing on a bronze-bonded diamond grinding wheel. This study provides theoretical guidance for optimising the process parameters in the laser ablation of a bronze-bonded diamond grinding wheel. A comparative analysis showed that the numerical solution to the model is in good agreement with the experimental data, thus verifying the correctness and feasibility of the heat transfer model.

  17. Numerical modelling of thermal effects on biological tissue during laser-material interaction

    NASA Astrophysics Data System (ADS)

    Latinovic, Z.; Sreckovic, M.; Janicijevic, M.; Ilic, J.; Radovanovic, J.

    2014-09-01

    Among numerous methods of the modelling of laser interaction with the material equivalent of biological tissue (including macroscopic and microscopic cell interaction), the case of pathogenic prostates is chosen to be studied. The principal difference between the inorganic and tissue equivalent material is the term which includes blood flow. Thermal modelling is chosen for interaction mechanisms, i.e. bio-heat equation. It was noticed that the principal problems are in selecting appropriate numerical methods, available mathematical program packages and finding all exact parameters for performing the needed calculations. As principal parameters, among them density, heat conduction, and specific heat, there are many other parameters which depend on the chosen approach (there could be up to 20 parameters, among them coefficient of time scaling, arterial blood temperature, metabolic heat source, etc). The laser type, including its wavelength which defines the quantity of absorbed energy and dynamic of irradiation, presents the term which could be modulated for the chosen problem. In this study, the program Comsol Multiphysics 3.5 is used in the simulation of prostate exposed to Nd3+:YAG laser in its fundamental mode.

  18. High-speed laser-assisted cutting of strong transparent materials using picosecond Bessel beams

    NASA Astrophysics Data System (ADS)

    Bhuyan, M. K.; Jedrkiewicz, O.; Sabonis, V.; Mikutis, M.; Recchia, S.; Aprea, A.; Bollani, M.; Trapani, P. Di

    2015-08-01

    We report single-pass cutting of strong transparent glass materials of 700 μm thickness with a speed up to 270 mm/s using single-shot nanostructuring technique exploiting picosecond, zero-order Bessel beams at laser wavelength of 1030 nm. Particularly, we present results of a systematic study of cutting of tempered glass which has high resistance to thermal and mechanical shocks due to the inhomogeneous material properties along its thickness, and homogeneous glass that identify a unique focusing geometry and a finite pitch dependency, for which cutting with high quality and high reproducibility can be achieved. These results represent a significant advancement in the field of high-speed cutting of technologically important transparent materials.

  19. Laser Measurement of SAM Bulk and Surface Wave Amplitudes for Material Microstructure Analysis

    SciTech Connect

    Ken L. Telschow; Chiaki Miyasaka; David L. Cottle

    2005-07-01

    Scanning Acoustic Microscopy (SAM) at ultra high frequencies has proven to be a useful tool for investigating materials on the scale of individual grains. This technique is normally performed in a reflection mode from one side of a sample surface. Information about the generation and transmission of bulk acoustic waves into the material is inferred from the reflection signal amplitude. We present an adaptation to the SAM method whereby the acoustic bulk waves are directly visualized through laser acoustic detection. Ultrasonic waves were emitted from a nominal 200 MHz point focus acoustic lens into a thin silicon plate (thickness 75ìm) coupled with distilled water. A scanned laser beam detected the bulk and surface acoustic waves at the opposite surface of the thin silicon plate. Distinct amplitude patterns exhibiting the expected symmetry for Silicon were observed that alter in predictable ways as the acoustic focal point was moved throughout the plate. Predictions of the acoustic wave fields generated by the acoustic lens within and at the surface of the Silicon are being investigated through the angular spectrum of plane waves approach. Results shall be presented for plates with (100) and (111) orientations followed by discussion of applications of the technique for material microstructure analysis.

  20. UV laser-surface interactions relevant to analytic spectroscopy of wide bandgap materials

    SciTech Connect

    Dickinson, J.T.

    1993-12-31

    Laer ablation has application in materials analysis, surface modification, and thin film deposition. Processes that lead to emission and formation of particles when wide band gap materials are irradiated with pulsed uv laser light. These materials are often difficult to transport into the gas phase for analysis. Such materials are alkali halides, MgO.

  1. Laser Induced Reverse Transfer with metal and hybrid material prepared with sol-gel process used on glass substrate

    NASA Astrophysics Data System (ADS)

    Flury, Manuel; Pédri, Claude

    2013-08-01

    This article presents a possible use of Laser Induced Reverse Transfer (LIRT) for metal deposition combined with hybrid material prepared using the sol-gel process. The goal was to obtain two dimensional metal gratings with inorganic-organic hybrid material protection on low cost glass substrates. The hybrid material using the sol-gel material is employed here to give better adhesion of metal deposited by LIRT on glass substrates, and also to possibly cover the metal structure. The hybrid material was an organically modified silicate glass based on methacryloxypropyltri-methoxysilane (MATPMS) and zirconium propoxide. The proposed process permits to prototype rapidly small diffractive structure in amplitude mode or to mark two dimensional complicated patterns without complex technologies employing a focalized and computer controlled Nd-YAG laser at 1064 nm. The different steps of the technology are also discussed.

  2. CHALLENGES IN DEVELOPING MATERIALS FOR FUSION TECHNOLOGY PAST, PRESENT AND FUTURE

    SciTech Connect

    Zinkle, Steven J

    2013-01-01

    A brief historical review of the evolution in structural materials options for fusion energy systems is presented, along with the author s perspective on emerging trends in advanced manufacturing techniques and new high-performance materials.

  3. Multiple pulse thermal damage thresholds of materials for x-ray free electron laser optics investigated with an ultraviolet laser

    SciTech Connect

    Hau-Riege, Stefan P.; London, Richard A.; Bionta, Richard M.; Soufli, Regina; Ryutov, Dmitri; Shirk, Michael; Baker, Sherry L.; Smith, Patrick M.; Nataraj, Pradeep

    2008-11-17

    Optical elements to be used for x-ray free electron lasers (XFELs) must withstand multiple high-fluence pulses. We have used an ultraviolet laser to study the damage of two candidate materials, crystalline Si and B{sub 4}C-coated Si, emulating the temperature profile expected to occur in optics exposed to XFEL pulses. We found that the damage threshold for 10{sup 5} pulses is {approx}20% to 70% lower than the melting threshold.

  4. The effect of process variables on microstructure in laser-deposited materials

    NASA Astrophysics Data System (ADS)

    Bontha, Srikanth

    Laser deposition of titanium alloys is under consideration for aerospace applications, which require the consistent control of microstructure and resulting mechanical properties. To date, only limited experimental data exists to link deposition process variables (e.g., laser power and velocity) to resulting microstructure (e.g., grain size and morphology) in laser-deposited materials, and suitable microstructures have typically been obtained only by trial and error. In addition, it is unclear whether knowledge based on small-scale laser deposition processes (e.g., LENS(TM)) can be applied to large-scale (higher power) processes currently under development for commercial applications. Therefore, simulation-based methods are needed to predict the effects of process variables and size-scale on microstructure in laser-deposited titanium and other aerospace materials. The ability to predict and control microstructure in laser deposition processes requires an understanding of the thermal conditions at the onset of solidification. The focus of this work is the development of thermal process maps relating solidification cooling rate and thermal gradient (the key parameters controlling microstructure) to laser deposition process variables (laser power and velocity). The approach employs the well-known Rosenthal solution for a moving point heat source traversing an infinite substrate. Cooling rates and thermal gradients at the onset of solidification are numerically extracted from the Rosenthal solution throughout the depth of the melt pool, and dimensionless process maps are presented for both 2-D thin-wall and bulky 3-D geometries. Results for both small-scale (LENS(TM)) and large-scale (higher power) processes are plotted on solidification maps for predicting trends in grain morphology in laser-deposited Ti-6Al-4V. Although the Rosenthal predictions neglect the nonlinear effects of temperature-dependent properties and latent heat of transformation, a comparison with 2-D

  5. Femtosecond laser damage threshold and nonlinear characterization in bulk transparent SiC materials

    SciTech Connect

    DesAutels, G. Logan; Finet, Marc; Ristich, Scott; Whitaker, Matt; Brewer, Chris; Juhl, Shane; Walker, Mark; Powers, Peter

    2008-01-15

    Semi-insulating and conducting SiC crystalline transparent substrates were studied after being processed by femtosecond (fs) laser radiation (780 nm at 160 fs). Z-scan and damage threshold experiments were performed on both SiC bulk materials to determine each sample's nonlinear and threshold parameters. 'Damage' in this text refers to an index of refraction modification as observed visually under an optical microscope. In addition, a study was performed to understand the damage threshold as a function of numerical aperture. Presented here for the first time, to the best of our knowledge, are the damage threshold, nonlinear index of refraction, and nonlinear absorption measured values.

  6. Present and Future of Laser Accelerator 1.History and Future Prospect

    NASA Astrophysics Data System (ADS)

    Kitagawa, Yoneyoshi

    Plasma is an attractive medium for the advanced accelerator. When combined with the ultra-intense lasers, it makes the acceleration field one thousand times the field of the current microwave accelerators or the size one thousandth the size. The fields, which require now the particle accelerator, are not only the high energy physics, but also the medical, industrial and low energy material fields. In these 10 years, the laser accelerator research has advanced the electron gain of from 22 MeV to 200 MeV. Recently, it has produced 200 MeV electrons from a 2 mm-long plasma. This corresponds to 100 GV/m. On the other hand, a glass capillary has this year succeeded in making the plasma length, the acceleration length, from 2 mm to 10 mm. Mono-energetic peaks were also found. These will be the breakthrough to the second generation of the advanced accelerator development.This review introduces these topics as well as the development of the ion acceleration studies.

  7. Acousto-ultrasonic nondestructive evaluation of materials using laser beam generation and detection

    NASA Technical Reports Server (NTRS)

    Huber, Robert D.; Green, Robert E., Jr.; Vary, Alex; Kautz, Harold

    1990-01-01

    Presented in viewgraph format, the possibility of using laser generation and detection of ultrasound to replace piezoelectric transducers for the acousto-ultrasonic technique is advanced. The advantages and disadvantages of laser acousto-ultrasonics are outlined. Laser acousto-ultrasonics complements standard piezoelectric acousto-ultrasonics and offers non-contact nondestructive evaluation.

  8. Experimental and numerical studies on laser-based powder deposition of slurry erosion resistant materials

    NASA Astrophysics Data System (ADS)

    Balu, Prabu

    cracking issue, and 3) the effect of composition and composition gradient of Ni and WC on the slurry erosion resistance over a wide range of erosion conditions. This thesis presents a set of numerical and experimental methods in order to address the challenges mentioned above. A three-dimensional (3-D) computational fluid dynamics (CFD) based powder flow model and three vision based techniques were developed in order to visualize the process of feeding the Ni-WC powder in the LBPD process. The results provide the guidelines for efficiently feeding the Ni-WC composite powder into the laser-formed molten pool. The finite element (FE) based experimentally verified 3-D thermal and thermo-mechanical models are developed in order to understand the thermal and stress evolutions in Ni-WC composite material during the LBPD process. The models address the effect of the process variables, preheating temperature, and different mass fractions of WC in Ni on thermal cycles and stress distributions within the deposited material. The slurry erosion behavior of the single and multilayered deposits of Ni-WC composite material produced by the LBPD process is investigated using an accelerated slurry erosion testing machine and a 3-D FE dynamic model. The verified model is used to identify the appropriate composition and composition gradient of Ni-WC composite material required to achieve erosion resistance over a wide range of erosion conditions.

  9. Femtosecond pulsed laser processing of electronic materials: Fundamentals and micro/nano-scale applications

    NASA Astrophysics Data System (ADS)

    Choi, Tae-Youl

    Ultra-short pulsed laser radiation has been shown to be effective for precision materials processing and surface micro-modification. One of advantages is the substantial reduction of the heat penetration depth, which leads to minimal lateral damage. Other advantages include non-thermal nature of ablation process, controlled ablation and ideal characteristics for precision micro-structuring. Yet, fundamental questions remain unsolved regarding the nature of melting and ablation mechanisms in femtosecond laser processing of materials. In addition to micro engineering problems, nano-structuring and nano-fabrication are emerging fields that are of particular interest in conjunction with femtosecond laser processing. A comprehensive experimental study as well as theoretical development is presented to address these issues. Ultra-short pulsed laser irradiation was used to crystallize 100 nm amorphous silicon (a-Si) films. The crystallization process was observed by time-resolved pump-and-probe reflection imaging in the range of 0.2 ps to 100 ns. The in-situ images in conjunction with post-processed SEM and AFM mapping of the crystallized structure provide evidence for non-thermal ultra-fast phase transition and subsequent surface-initiated crystallization. Mechanisms of ultra-fast laser-induced ablation on crystalline silicon and copper are investigated by time-resolved pump-and-probe microscopy in normal imaging and shadowgraph arrangements. A one-dimensional model of the energy transport is utilized to predict the carrier temperature and lattice temperature as well as the electron and vapor flux emitted from the surface. The temporal delay between the pump and probe pulses was set by a precision translation stage up to about 500 ps and then extended to the nanosecond regime by an optical fiber assembly. The ejection of material was observed at several picoseconds to tens of nanoseconds after the main (pump) pulse by high-resolution, ultra-fast shadowgraphs. The

  10. Cr.sup.3+-doped laser materials and lasers and methods of making and using

    NASA Technical Reports Server (NTRS)

    Alfano, Robert R. (Inventor); Bykov, Alexey (Inventor); Petricevic, Vladimir (Inventor); Sharonov, Mikhail (Inventor)

    2008-01-01

    A laser medium includes a single crystal of chromium-doped LiSc.sub.l-xIn.sub.xGe.sub.1-ySi.sub.yO.sub.4, where 0.ltoreq.x.ltoreq.1 and 0.ltoreq.y.ltoreq.1. Preferably, x and y are not both 0. A laser, such as a tunable near infrared laser, can contain the laser medium.

  11. Thermostructural Analysis of Carbon Cloth Phenolic Material Tested at the Laser Hardened Material Evaluation Laboratory

    NASA Technical Reports Server (NTRS)

    Clayton, J. Louie; Ehle, Curt; Saxon, Jeff (Technical Monitor)

    2002-01-01

    RSRM nozzle liner components have been analyzed and tested to explore the occurrence of anomalous material performance known as pocketing erosion. Primary physical factors that contribute to pocketing seem to include the geometric permeability, which governs pore pressure magnitudes and hence load, and carbon fiber high temperature tensile strength, which defines a material limiting capability. The study reports on the results of a coupled thermostructural finite element analysis of Carbon Cloth Phenolic (CCP) material tested at the Laser Hardened Material Evaluation Laboratory (the LHMEL facility). Modeled test configurations will be limited to the special case of where temperature gradients are oriented perpendicular to the composite material ply angle. Analyses were conducted using a transient, one-dimensional flow/thermal finite element code that models pore pressure and temperature distributions and in an explicitly coupled formulation, passes this information to a 2-dimensional finite element structural model for determination of the stress/deformation behavior of the orthotropic fiber/matrix CCP. Pore pressures are generated by thermal decomposition of the phenolic resin which evolve as a multi-component gas phase which is partially trapped in the porous microstructure of the composite. The nature of resultant pressures are described by using the Darcy relationships which have been modified to permit a multi-specie mass and momentum balance including water vapor condensation. Solution to the conjugate flow/thermal equations were performed using the SINDA code. Of particular importance to this problem was the implementation of a char and deformation state dependent (geometric) permeability as describing a first order interaction between the flow/thermal and structural models. Material property models are used to characterize the solid phase mechanical stiffness and failure. Structural calculations were performed using the ABAQUS code. Iterations were made

  12. Surface-enhanced Raman scattering on optical material fabricated by femtosecond laser

    NASA Astrophysics Data System (ADS)

    Wang, Wenhui; Huo, Haibin; Wu, Nan; Shen, Mengyan; Guthy, Charles; Wang, Xingwei

    2010-04-01

    Raman spectroscopy is a technology that can detect and distinguish materials based on the materials' Raman scattering. However, the signal produced using this technology is usually too small to be useful. The Raman spectrum signal can be enhanced by creating rough patches on the surface of the material. In this paper, a novel method to produce nanometer-sized features on optical materials such as glass, fused silica, and quartz substrate is presented. Using a femtosecond laser, the transparent materials are sputtered and deposited. When the materials cool down, they produce structures with nano-features. These nano-features on optical materials can make designing optical sensing systems much easier. Scanning electron microscope photos of nano-structures on quartz substrate and optical fiber show that features less than 100 nm in size have been successfully fabricated. The 3D micro- and nano-structures of the sensor were studied using a confocal Raman spectrum microscope and focused ion-beam milling. Raman spectrum signals show that the strength of the signal generated by Raman scattering was greatly enhanced compared to substrates without nano-features.

  13. Laser materials processing applications at Lawrence Livermore National Laboratory

    NASA Astrophysics Data System (ADS)

    Hargrove, R. S.; Dragon, Ernest P.; Hackel, Richard P.; Kautz, Douglas D.; Warner, Bruce E.

    1993-05-01

    Copper and dye laser systems are currently being developed at LLNL for uranium enrichment production facilities. The goals of this program are to develop low-cost, reliable and maintainable industrial laser systems. Chains of copper lasers currently operate at more than 1.5 kW output and achieve mean time between failures of more than 1000 hours. The beam quality of copper vapor lasers is approximately three times the diffraction limit. Dye lasers have near diffraction limited beam quality at greater than 1.0 kW. Diode laser pumped, Nd:YAG slab lasers are also being developed at LLNL. Current designs achieve powers of greater than 1.0 kW and projected beam quality is in the two to five times diffraction limited range. Results from cutting and drilling studies in titanium and stainless steel alloys show that cuts and holes with extremely fine features can be made with dye and copper-vapor lasers. High radiance beams produce low distortion and small heat-affected zones. We have accomplished very high aspect ratio holes in drilling tests (> 60:1) and features with micron scale (5 - 50 micrometers ) sizes.

  14. Design and operation of a highly sensitive and accurate laser calorimeter for low-absorbtion materials

    NASA Astrophysics Data System (ADS)

    Kawate, Etsuo; Hanssen, Leonard M.; Kaplan, Simon G.; Datla, Raju V.

    1998-10-01

    This work surveys techniques to measure the absorption coefficient of low absorption materials. A laser calorimeter is being developed with a sensitivity goal of (1 +/- 0.2)X 10-5 cm-1 with one watt of laser power using a CO2 laser (9 (mu) m to 11 (mu) m), a CO laser (5 (mu) m to 8 (mu) m), a He-Ne laser (3.39 (mu) m), and a pumped OPO tunable laser (2 (mu) m to 4 (mu) m) in the infrared region. Much attention has been given to the requirements for high sensitivity and to sources of systematic error including stray light. Our laser calorimeter is capable of absolute electrical calibration. Preliminary results for the absorption coefficient of highly transparent potassium chloride (KCl) samples are reported.

  15. Study of the effect of properties of material on vacuum breakdown initiated by laser radiation

    SciTech Connect

    Seleznev, V. P.; Revazov, V. O.

    2015-12-15

    In this work, the effect of various properties of materials on vacuum breakdown initiated by laser radiation is considered. Estimating calculations are performed which show that the material of the target electrode distinctly affects the minimum energy of laser radiation needed for igniting a vacuum spark. The experimental studies carried out confirm the estimating calculations, and a number of materials are revealed which can be arranged in order of increase in the energy needed for the formation of breakdown in vacuum by the impact of a laser pulse.

  16. Implementing New Methods of Laser Marking of Items in the Nuclear Material Control and Accountability System at SSC RF-IPPE: An Automated Laser Marking System

    SciTech Connect

    Regoushevsky, V I; Tambovtsev, S D; Dvukhsherstnov, V G; Efimenko, V F; Ilyantsev, A I; Russ III, G P

    2009-05-18

    For over ten years SSC RF-IPPE, together with the US DOE National Laboratories, has been working on implementing automated control and accountability methods for nuclear materials and other items. Initial efforts to use adhesive bar codes or ones printed (painted) onto metal revealed that these methods were inconvenient and lacked durability under operational conditions. For NM disk applications in critical stands, there is the additional requirement that labels not affect the neutron characteristics of the critical assembly. This is particularly true for the many stainless-steel clad disks containing highly enriched uranium (HEU) and plutonium that are used at SSC RF-IPPE for modeling nuclear power reactors. In search of an alternate method for labeling these disks, we tested several technological options, including laser marking and two-dimensional codes. As a result, the method of laser coloring was chosen in combination with Data Matrix ECC200 symbology. To implement laser marking procedures for the HEU disks and meet all the nuclear material (NM) handling standards and rules, IPPE staff, with U.S. technical and financial support, implemented an automated laser marking system; there are also specially developed procedures for NM movements during laser marking. For the laser marking station, a Zenith 10F system by Telesis Technologies (10 watt Ytterbium Fiber Laser and Merlin software) is used. The presentation includes a flowchart for the automated system and a list of specially developed procedures with comments. Among other things, approaches are discussed for human-factor considerations. To date, markings have been applied to numerous steel-clad HEU disks, and the work continues. In the future this method is expected to be applied to other MC&A items.

  17. Multiscale analysis: a way to investigate laser damage precursors in materials for high power applications at nanosecond pulse duration

    NASA Astrophysics Data System (ADS)

    Natoli, J. Y.; Wagner, F.; Ciapponi, A.; Capoulade, J.; Gallais, L.; Commandré, M.

    2010-11-01

    The mechanism of laser induced damage in optical materials under high power nanosecond laser irradiation is commonly attributed to the presence of precursor centers. Depending on material and laser source, the precursors could have different origins. Some of them are clearly extrinsic, such as impurities or structural defects linked to the fabrication conditions. In most cases the center size ranging from sub-micrometer to nanometer scale does not permit an easy detection by optical techniques before irradiation. Most often, only a post mortem observation of optics permits to proof the local origin of breakdown. Multi-scale analyzes by changing irradiation beam size have been performed to investigate the density, size and nature of laser damage precursors. Destructive methods such as raster scan, laser damage probability plot and morphology studies permit to deduce the precursor densities. Another experimental way to get information on nature of precursors is to use non destructive methods such as photoluminescence and absorption measurements. The destructive and non destructive multiscale studies are also motivated for practical reasons. Indeed LIDT studies of large optics as those used in LMJ or NIF projects are commonly performed on small samples and with table top lasers whose characteristics change from one to another. In these conditions, it is necessary to know exactly the influence of the different experimental parameters and overall the spot size effect on the final data. In this paper, we present recent developments in multiscale characterization and results obtained on optical coatings (surface case) and KDP crystal (bulk case).

  18. Femtosecond laser patterning of lithium-ion battery separator materials: impact on liquid electrolyte wetting and cell performance

    NASA Astrophysics Data System (ADS)

    Pröll, J.; Schmitz, B.; Niemöeller, A.; Robertz, B.; Schäfer, M.; Torge, M.; Smyrek, P.; Seifert, H. J.; Pfleging, W.

    2015-03-01

    High capacity Li-ion batteries are composed of alternating stacked cathode and anode layers with thin separator membranes in between for preventing internal shorting. Such batteries can suffer from insufficient cell reliability, safety and electrochemical performance due to poor liquid electrolyte wetting properties. Within the electrolyte filling process, homogeneous wetting of cathode, separator and anode layers is strongly requested due to the fact that insufficient electrolyte wetting of battery components can cause limited capacity under challenging operation or even battery failure. The capacity of the battery is known to be limited by the quantity of wetting of the electrode and separator layers. Therefore, laser structuring processes have recently been developed for forming capillary micro-structures into cathode and anode layers leading to improved wetting properties. Additionally, many efforts have been undertaken to enhance the wettability and safety issues of separator layers, e.g. by applying thin coatings to polymeric base materials. In this paper, we present a rather new approach for ultrafast femtosecond laser patterning of surface coated separator layers. Laser patterning allows the formation of micro-vias and micro-channel structures into thin separator membranes. Liquid electrolyte wetting properties were investigated before and after laser treatment. The electrochemical cyclability of batteries with unstructured and laser-structured separators was tested in order to determine an optimal combination with respect to separator material, functional coating and laser-induced surface topography.

  19. Fundamentals of Composite Materials for Undergraduate Engineering--A Filmed Presentation. Final Report.

    ERIC Educational Resources Information Center

    Busching, Herbert W.

    Curricula in undergraduate engineering have not adequately reflected present usage and knowledge of composite materials (types of rock and organic matter in which structurally dissimilar materials are combined). Wide usage of composites is expected to increase the importance of this class of materials and the need for more substantive exposure to…

  20. Performance and Reliability of Interface Materials for Automotive Power Electronics (Presentation)

    SciTech Connect

    Narumanchi, S.; DeVoto, D.; Mihalic, M.; Paret, P.

    2013-07-01

    Thermal management and reliability are important because excessive temperature can degrade the performance, life, and reliability of power electronics and electric motors. Advanced thermal management technologies enable keeping temperature within limits; higher power densities; and lower cost materials, configurations and systems. Thermal interface materials, bonded interface materials and the reliability of bonded interfaces are discussed in this presentation.

  1. Effective transvascular drug delivery to glioma in rats by using a pulsed laser-induced photomechanical wave (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Akutsu, Yusuke; Sato, Shunichi; Tomiyama, Arata; Tsunoi, Yasuyuki; Kawauchi, Satoko; Mori, Kentaro; Terakawa, Mitsuhiro

    2016-03-01

    Glioma is one of the most aggressive cancers, for which efficacy of conventional chemotherapy is often limited due to the blood-tumor barrier (BTB). Thus, the development of a method for enhancing the BTB permeability is strongly desired. In this study, we applied a photomechanical wave (PMW), which was generated by the irradiation of a light-absorbing material with a nanosecond laser pulse, to transiently open the BTB in a rat intracranial glioma model using C6 cells. A tumor was grown in the both hemispheres, and a solution of Evans blue (EB), as a test drug, was injected into the tail vein. Thereafter, we applied a PMW generated at a laser fluence of 0.2 J/cm2 (averaged peak pressure, ~27 MPa), 0.4 J/cm2 (~54 MPa) or 0.6 J/cm2 (~78MPa), to one hemisphere through the cranial window, while the other hemisphere served as a control. Four hours later, the rat was perfused, and we compared intensity distributions of EB fluorescence between the both hemispheres. Intensities of EB fluorescence both in the peritumoral and tumor core regions were increased with increasing the laser fluence, but hemorrhage was observed at the highest fluence. Thus, 0.4 J/cm2 would be optimum for efficient and safe BTB opening. On the basis of fluorescence microscopy with the use of enhanced green fluorescent protein-expressing C6 cells, we confirmed that a drug was delivered into targeted glioma cells in the peritumoral region. These results show the validity of the present transvascular drug delivery method to glioma.

  2. A study of the effect of multiple reflections on the shape of the keyhole in the laser processing of materials

    NASA Astrophysics Data System (ADS)

    Solana, Pablo; Negro, Guillermo

    1997-12-01

    In the deep penetration laser welding of materials as well as in other laser material processing it is usual for the laser to generate a keyhole in the material. One of the principal mechanisms of energy absorption in the keyhole is the Fresnel absorption process on the keyhole wall. In order to take account of the Fresnel absorption process properly it is necessary to include the effect of multiple reflections in the keyhole. With this end in view an axisymmetrical numerical model is presented in which the keyhole geometry is not fixed at the outset, but instead the keyhole wall is considered to be a free boundary whose shape changes after each iteration in the numerical process. In this connection each complete set of reflections constitutes a step in the iteration process. Convergence is reached for a reasonably wide set of initial geometries and discretization steps. The model is used to analyse keyhole profiles and intensity distributions with depth for the cases of a Gaussian and of a uniform top-hat distribution in the laser beam. The model allows the effect of inverse bremsstrahlung absorption in the keyhole to be taken into account, this being the other principal mechanism for the absorption of laser light in the keyhole.

  3. A general continuum approach to describe fast electronic transport in pulsed laser irradiated materials: The problem of Coulomb explosion

    NASA Astrophysics Data System (ADS)

    Bulgakova, N. M.; Stoian, R.; Rosenfeld, A.; Hertel, I. V.; Marine, W.; Campbell, E. E. B.

    2005-07-01

    We present a continuum model, based on a drift-diffusion approach, aimed at describing the dynamics of electronic excitation, heating, and charge-carrier transport in different materials (metals, semiconductors, and dielectrics) under femtosecond and nanosecond pulsed laser irradiation. The laser-induced charging of the targets is investigated at laser intensities above the material removal threshold. It is demonstrated that, for near-infrared femtosecond irradiation, charging of dielectric surfaces causes a sub-picosecond electrostatic rupture of the superficial layers, alternatively called Coulomb explosion (CE), while this effect is strongly inhibited for metals and semiconductors as a consequence of superior carrier transport properties. On the other hand, application of the model to UV nanosecond pulsed laser interaction with bulk silicon has pointed out the possibility of Coulomb explosion in semiconductors. For such regimes a simple analytical theory for the threshold laser fluence of CE has been developed, showing results in agreement with the experimental observations. Various related aspects concerning the possibility of CE depending on different irradiation parameters (fluence, wavelength and pulse duration) and material properties are discussed. This includes the temporal and spatial dynamics of charge-carrier generation in non-metallic targets and evolution of the reflection and absorption characteristics.

  4. Further remarks on electron beam pumping of laser materials.

    PubMed

    Klein, C A

    1966-12-01

    This article demonstrates that recently completed studies on the energy dissipation of kilovolt electron beams in solids provide readily applicable methods for assessing the situation in electron beam pumped lasers. PMID:20057662

  5. Present status of the NIJI-IV storage-ring free-electron lasers

    SciTech Connect

    Yamazaki, T.; Yamada, K.; Sei, N.

    1995-12-31

    The tunable region of the free-electron-laser (FEL) wavelength with the NIJI-IV system is now 348{approximately}595 nm. After the lasing at 352 nm in 1994, the quality of the electron beam stored in the ring has been improved further, and the highest peak intensity of the laser obtained so far is more than 300 times as high as that of the resonated spontaneous emission. The macro-temporal structure of the lasing has been greatly improved. Recently, a single-bunch injection system was completed, and the system has been installed in the injector linac, which is expected to increase the peak stored-beam current. The commissioning and the test of the new system is under way. The beam transporting system from the linac to the ring is also being modified by increasing the number of quadrupole magnets. The experiments related to the FEL in the ultraviolet wavelength region will be begun in this coming May. The results and the status of the FEL experiments will be presented at the Conference.

  6. III-V GaAs based plasmonic lasers (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Lafone, Lucas; Nguyen, Ngoc; Clarke, Ed; Fry, Paul; Oulton, Rupert F.

    2015-09-01

    Plasmonics is a potential route to new and improved optical devices. Many predict that sub wavelength optical systems will be essential in the development of future integrated circuits, offering the only viable way of simultaneously increasing speed and reducing power consumption. Realising this potential will be contingent on the ability to exploit plasmonic effects within the framework of the established semiconductor industry and to this end we present III-V (GaAs) based surface plasmon laser platform capable of effective laser light generation in highly focussed regions of space. Our design utilises a suspended slab of GaAs with a metallic slot printed on top. Here, hybridisation between the plasmonic mode of the slot and the photonic mode of the slab leads to the formation of a mode with confinement and loss that can be adjusted through variation of the slot width alone. As in previous designs the use of a hybrid mode provides strong confinement with relatively low losses, however the ability to print the metal slot removes the randomness associated with device fabrication and the requirement for etching that can deteriorate the semiconductor's properties. The deterministic fabrication process and the use of bulk GaAs for gain make the device prime for practical implementation.

  7. Optical Absorption of Epoxy Resin and its Role in the Laser Ultrasonic Generation Mechanism in Composite Materials

    NASA Astrophysics Data System (ADS)

    Stratoudaki, T.; Edwards, C.; Dixon, S.; Palmer, S. B.

    2003-03-01

    Epoxy resins are used in various applications and are essential to the fabrication of carbon fibre reinforced composite materials (CFRCs). This paper investigates laser generated ultrasound in epoxy resins using three different lasers, a TEA CO2, a Nd:YAG and a XeCl excimer. In these partially transparent materials the ultrasonic generation mechanism is directly related to the optical absorption depth which can therefore be measured directly from the ultrasonic waveforms using for example a Michelson interferometer as detector. The present work aims firstly to relate the observed amplitude of the longitudinal wave to the optical absorption depth of the epoxy and secondly to evaluate the role of the epoxy resin to the generation of the ultrasound in CFRCs. For the latter, comparative results of generation efficiency between the three wavelengths are presented and an attempt is made to understand the way that the resin matrix influences the generation mechanism of ultrasound in composite materials.

  8. Thermal and radiative transport analysis of laser ignition of energetic materials

    NASA Astrophysics Data System (ADS)

    Damm, D.; Maiorov, M.

    2010-08-01

    Laser ignition of energetic materials is an attractive technology for replacement of low energy electro-explosive devices which pose a safety hazard. The development of this technology has historically been based on go/no-go threshold testing using off-the-shelf laser diodes and solid state lasers. Here we seek to build a more fundamental understanding of the laser ignition process by analyzing the interactions and response of the energetic material to the incident laser beam. We begin with a radiative heat transfer model of the laser-beam-assisted heating of a homogeneous energetic material with given optical properties. An analytical solution of the 2-flux model equations is developed and this expression for the volumetric absorption of laser energy in an absorbing and isotropically scattering medium is coupled to the conservation of energy equation. Two limiting cases-minimum power and minimum energy thresholds for ignition - are discussed, and the minimum energy threshold is calculated directly from the energy equation in the limit of zero dissipative losses. The effects of power density and beam shape are of particular interest and two common configurations are analyzed. Although the applicability of thermal models is limited by large uncertainties in the optical properties of energetic materials, the analysis provides a qualitative understanding of the ignition process and a correlation between ignition thresholds and the various material properties and design parameters.

  9. Spectroscopic, luminescent and laser properties of nanostructured CaF2:Tm materials

    NASA Astrophysics Data System (ADS)

    Lyapin, A. A.; Fedorov, P. P.; Garibin, E. A.; Malov, A. V.; Osiko, V. V.; Ryabochkina, P. A.; Ushakov, S. N.

    2013-08-01

    The laser quality transparent СаF2:Tm fluoride ceramics has been prepared by hot forming. Comparative study of absorption and emission spectra of СаF2:Tm (4 mol.% TmF3) ceramic and single crystal samples demonstrated that these materials possess almost identical spectroscopic properties. Laser oscillations of СаF2:Tm ceramics were obtained at 1898 nm under diode pumping, with the slope efficiency of 5.5%. Also, the continuous-wave (CW) laser have been obtained for СаF2:Tm single crystal at 1890 nm pumped by a diode laser was demonstrated.

  10. Influence of gel/LED-laser application on cervical microleakage of two barrier materials used for endodontically treated teeth whitening

    NASA Astrophysics Data System (ADS)

    Marchesan, Melissa Andréia; Barros, Felipe; Porto, Saulo; Zaitter, Suellen; Brugnera, Aldo, Jr.; Sousa-Neto, Manoel D.

    2007-02-01

    This study evaluated ex vivo the influence of the number of gel/LED-laser applications/activations on cervical microleakage of two different barrier materials used for protection during whitening of endodontically treated teeth. Eighty-four canines were instrumented and obturated with epoxy resin sealer. The seal was removed 2 mm beyond the cemento-enamel junction for barrier placement and the teeth were divided into two groups of 40 teeth each: G1, zinc phosphate cement; G2, glass ionomer cement. The two groups were subdivided into 4 subgroups (n=10 each): I) no gel or LED-laser application; II) one gel application and two LED-laser activations; III) two gel applications and four LED-laser activations; IV) three gel applications and six LED-laser activations. The teeth were immersed in India ink for 7 days, decalcified and cleared. Cervical microleakage was quantified with a measurement microscope. Statistical analysis showed that zinc phosphate caused significantly lower microleakage than glass ionomer cement (presented microleakage in all subgroups). However, after two (p<0.01) and three (p<0.001) applications of gel, there was statistially significant microleakage in zinc phosphate barriers. Based on the present results, it can be concluded that cervical barriers with zinc phosphate cement show less cervical microleakage and that two or more applications/activations of gel/LED-laser significantly increase microleakage.

  11. Actual principles of the simulation of state-of-the-art technologies of laser processing of materials

    NASA Astrophysics Data System (ADS)

    Kovalev, Oleg B.

    2011-02-01

    Here we present the results of mathematical, numerical, and experimental simulation of the processes of interaction between the laser radiation and metals in the technologies of gas-laser cutting of thick-sheet materials and laser gas-powder cladding at the production of coatings and 3D objects by the DMD (Direct Material Deposition) method. The peculiarities of jet 3D flows of the working gases in narrow channels, geometrically identical to keyholes, are studied. It is demonstrated that during the stainless steel cutting, supersonic gas flows form local regions of separation flows which in turn result in the worse carry-away of the metal by the gas flow; these factors increase the roughness (striation) and worsen the surface quality. A vortex flow was found inside the cut at the subsonic jet flows typical for the oxygen gas-laser cutting of low-carbon steel; this flow causes slagging of the cut bottom edge. The processes running inside the laser cut at the fusible metals cutting with the low-power radiation were visualized under the laboratory conditions. Some new concepts of the processes running inside the keyhole have been gained; we also propose the explanations of the mechanisms of striation and other surface defects formation during the cutting of thick-sheet standard metals on the automate laser technological complex. A mathematical model of the volumetric laser-powder cladding is proposed. The submitted results concern the numerical simulation of multi-layer flows of shaping and carrier gases with the gas-jet transportation of powder particles into the laser spot on the substrate.

  12. Actual principles of the simulation of state-of-the-art technologies of laser processing of materials

    NASA Astrophysics Data System (ADS)

    Kovalev, Oleg B.

    2010-07-01

    Here we present the results of mathematical, numerical, and experimental simulation of the processes of interaction between the laser radiation and metals in the technologies of gas-laser cutting of thick-sheet materials and laser gas-powder cladding at the production of coatings and 3D objects by the DMD (Direct Material Deposition) method. The peculiarities of jet 3D flows of the working gases in narrow channels, geometrically identical to keyholes, are studied. It is demonstrated that during the stainless steel cutting, supersonic gas flows form local regions of separation flows which in turn result in the worse carry-away of the metal by the gas flow; these factors increase the roughness (striation) and worsen the surface quality. A vortex flow was found inside the cut at the subsonic jet flows typical for the oxygen gas-laser cutting of low-carbon steel; this flow causes slagging of the cut bottom edge. The processes running inside the laser cut at the fusible metals cutting with the low-power radiation were visualized under the laboratory conditions. Some new concepts of the processes running inside the keyhole have been gained; we also propose the explanations of the mechanisms of striation and other surface defects formation during the cutting of thick-sheet standard metals on the automate laser technological complex. A mathematical model of the volumetric laser-powder cladding is proposed. The submitted results concern the numerical simulation of multi-layer flows of shaping and carrier gases with the gas-jet transportation of powder particles into the laser spot on the substrate.

  13. Characteristics of a Laser Resonant Ultrasonic Spectroscopy System for Measuring the Elastic Constants of Materials

    SciTech Connect

    Seung-Kyu Park; Sung-Hoon Baik; Hyung-Ki Cha; Stephen J. Reese; David H. Hurley

    2010-08-01

    Resonant ultrasound spectroscopy (RUS) is a useful technique for measuring the elastic properties of materials. In this study, two experimental approaches for performing RUS are experimentally analyzed and compared: 1) contact transduction using piezoelectric transducers (PZT) and 2) laser transduction using pulse laser excitation and laser interferometric detection. A single Zircaloy sample cut from a nuclear pressure tube was used for this study. By virtue of the non-contact nature, the quality factor, Q, for laser RUS is shown to be higher than the contact RUS. In addition, the probe beam for laser-RUS can be scanned to form a 2D image of each vibrational mode, which in turn enables unique mode identification. These defining characteristics of laser-RUS enable straightforward discrimination of closely spaced resonant modes and provide key advantages for improving the resolution of resonant ultrasound spectroscopy.

  14. Using laser-induced thermal voxels to pattern diverse materials at the solid–liquid interface

    DOE PAGES

    Zarzar, Lauren D.; Swartzentruber, B. S.; Donovan, Brian F.; Hopkins, Patrick E.; Kaehr, Bryan

    2016-08-05

    We describe a high-resolution patterning approach that combines the spatial control inherent to laser direct writing with the versatility of benchtop chemical synthesis. By taking advantage of the steep thermal gradient that occurs while laser heating a metal edge in contact with solution, diverse materials comprising transition metals are patterned with feature size resolution nearing 1 μm. We demonstrate fabrication of reduced metallic nickel in one step and examine electrical properties and air stability through direct-write integration onto a device platform. In conclusion, this strategy expands the chemistries and materials that can be used in combination with laser direct writing.

  15. Methodology for materials analysis using swept-frequency feedback interferometry with terahertz frequency quantum cascade lasers.

    PubMed

    Taimre, Thomas; Bertling, Karl; Lim, Yah Leng; Dean, Paul; Indjin, Dragan; Rakić, Aleksandar D

    2014-07-28

    Recently, we demonstrated an interferometric materials analysis scheme at terahertz frequencies based on the self-mixing effect in terahertz quantum cascade lasers. Here, we examine the impact of variations in laser operating parameters, target characteristics, laser-target system properties, and the quality calibration standards on our scheme. We show that our coherent scheme is intrinsically most sensitive to fluctuations in interferometric phase, arising primarily from variations in external cavity length. Moreover we demonstrate that the smallest experimental uncertainties in the determination of extinction coefficients are expected for lossy materials.

  16. Using Laser-Induced Thermal Voxels to Pattern Diverse Materials at the Solid-Liquid Interface.

    PubMed

    Zarzar, Lauren D; Swartzentruber, B S; Donovan, Brian F; Hopkins, Patrick E; Kaehr, Bryan

    2016-08-24

    We describe a high-resolution patterning approach that combines the spatial control inherent to laser direct writing with the versatility of benchtop chemical synthesis. By taking advantage of the steep thermal gradient that occurs while laser heating a metal edge in contact with solution, diverse materials comprising transition metals are patterned with feature size resolution nearing 1 μm. We demonstrate fabrication of reduced metallic nickel in one step and examine electrical properties and air stability through direct-write integration onto a device platform. This strategy expands the chemistries and materials that can be used in combination with laser direct writing. PMID:27491598

  17. Internal temperature measurement of an ytterbium doped material under laser operation.

    PubMed

    Petit, J; Viana, B; Goldner, Ph

    2011-01-17

    Temperature of the pumped volume of an ytterbium doped material has been measured while laser action is taking place. This is achieved by recording green emissions at 530 and 550 nm from Er3+ impurities. These emissions result from energy transfer upconversion processes between Yb3+ and Er3+. Experiments performed on a Yb3+:CaGdAlO4 crystal show the effect of pump power and laser wavelength on the sample internal temperature. Temperature variation along the sample length has also been measured. This method can complement data obtained by thermal cameras which can only access surface temperatures in most laser materials.

  18. Picosecond laser ablation of poly-L-lactide: Effect of crystallinity on the material response

    SciTech Connect

    Ortiz, Rocio; Quintana, Iban; Etxarri, Jon; Lejardi, Ainhoa; Sarasua, Jose-Ramon

    2011-11-01

    The picosecond laser ablation of poly-L-lactide (PLLA) as a function of laser fluence and degree of crystallinity was examined. The ablation parameters and the surface modifications were analyzed under various irradiation conditions using laser wavelengths ranging from the ultraviolet through the visible. When processing the amorphous PLLA, both energy threshold and topography varied considerably depending on laser wavelength. Laser irradiation showed a reduction in the energy ablation threshold as the degree of crystallinity increased, probably related to photomechanical effects involved in laser ablation with ultra-short pulses and the lower stress accommodation behavior of semicrystalline polymers. In particular, cooperative chain motions are impeded by the higher degree of crystallinity, showing fragile mechanical behavior and lower energy dissipation. The experimental results on ablation rate versus laser energy showed that UV laser ablation on semicrystalline PLLA was more efficient than the visible ablation, i.e., it exhibits higher etch rates over a wide range of pulse energy conditions. These results were interpreted in terms of photo-thermal and photo-chemical response of polymers as a function of material micro-structure and incident laser wavelength. High quality micro-grooves were produced in amorphous PLLA, reveling the potential of ultra-fast laser processing technique in the field of micro-structuring biocompatible and biodegradable polymers for biomedical applications.

  19. Guided bone regeneration using an allograft material: review and case presentations.

    PubMed

    Bhola, Monish; Kinaia, Bassam M; Chahine, Katy

    2008-10-01

    Post extraction sites may have residual ridge deformities with insufficient bone present for future implant placement. This presents a challenge to the clinician attempting to obtain optimum results. To predictably augment these areas and obtain aesthetically pleasing results, bone grafting may be required. Guided bone regeneration with an allograft material is a predictable means by which to solve this challenge. This article describes three case presentations utilizing on allograft material for bone regeneration prior to implant placement.

  20. Fixation of bioactive calcium alkali phosphate on Ti6Al4V implant material with femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Symietz, Christian; Lehmann, Erhard; Gildenhaar, Renate; Koter, Robert; Berger, Georg; Krüger, Jörg

    2011-04-01

    Bone implants made of metal, often titanium or the titanium alloy Ti6Al4V, need to be surface treated to become bioactive. This enables the formation of a firm and durable connection of the prosthesis with the living bone. We present a new method to uniformly cover Ti6Al4V with a thin layer of ceramics that imitates bone material. These calcium alkali phosphates, called GB14 and Ca10, are applied to the metal by dip coating of metal plates into an aqueous slurry containing the fine ceramic powder. The dried samples are illuminated with the 790 nm radiation of a pulsed femtosecond laser. If the laser fluence is set to a value just below the ablation threshold of the ceramic (ca. 0.4 J/cm 2) the 30 fs laser pulses penetrate the partly transparent ceramic layer of 20-40 μm thickness. The remaining laser fluence at the ceramic-metal interface is still high enough to generate a thin metal melt layer leading to the ceramic fixation on the metal. The laser processing step is only possible because Ti6Al4V has a lower ablation threshold (between 0.1 and 0.15 J/cm 2) than the ceramic material. After laser treatment in a fluence range between 0.1 and 0.4 J/cm 2, only the particles in contact with the metal withstand a post-laser treatment (ultrasonic cleaning). The non-irradiated rest of the layer is washed off. In this work, we present results of a successful ceramic fixation extending over larger areas. This is fundamental for future applications of arbitrarily shaped implants.

  1. Probing of Metabolites in Finely Powdered Plant Material by Direct Laser Desorption Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Musharraf, Syed Ghulam; Ali, Arslan; Choudhary, M. Iqbal; Atta-ur-Rahman

    2014-04-01

    Natural products continue to serve as an important source of novel drugs since the beginning of human history. High-throughput techniques, such as MALDI-MS, can be techniques of choice for the rapid screening of natural products in plant materials. We present here a fast and reproducible matrix-free approach for the direct detection of UV active metabolites in plant materials without any prior sample preparation. The plant material is mechanically ground to a fine powder and then sieved through different mesh sizes. The collected plant material is dispersed using 1 μL solvent on a target plate is directly exposed to Nd:YAG 335 nm laser. The strategy was optimized for the analysis of plant metabolites after study of the different factors affecting the reproducibility and effectiveness of the analysis, including particle sizes effects, types of solvents used to disperse the sample, and the part of the plant analyzed. Moreover, several plant species, known for different classes of metabolites, were screened to establish the generality of the approach. The developed approach was validated by the characterization of withaferin A and nicotine in the leaves of Withania somnifera and Nicotiana tabacum, respectively, through comparison of its MS/MS data with the standard compound. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques were used for the tissue imaging purposes. This approach can be used to directly probe small molecules in plant materials as well as in herbal and pharmaceutical formulations for fingerprinting development.

  2. Material processing with 12 femtosecond picojoule laser pulses

    NASA Astrophysics Data System (ADS)

    König, Karsten; Licht, Martin; Straub, Martin; Uchugonova, Aisada

    2012-03-01

    Extremely short near infrared laser pulses (e.g. 10 fs) offer the possibility of precise sub-100nm processing without collateral side effects. Furthermore, the can be employed to excite a variety of absorbers simultaneously due to their broad 100 nm emission band. We demonstrate two-photon fluorescence imaging of green and red fluorescent proteins in living cells as well as two-photon nanolithography with 12 fs laser pulses (750-850 nm) at low microwatt mean power using an 85 MHz laser resonator. At a minimum of 400 μW mean power, direct nanoprocessing in blood cells was realized. Multiphoton ablation in biological specimens follows a P2/τ relation. We were able to create sub-100nm ripples in silicon wafers, to cut glass, gold, and polymers as well as to create transient nanoholes in the membranes of living stem cells and cancer cells for targeted transfection.

  3. Laser-induced growth of nanocrystals embedded in porous materials

    PubMed Central

    2013-01-01

    Space localization of the linear and nonlinear optical properties in a transparent medium at the submicron scale is still a challenge to yield the future generation of photonic devices. Laser irradiation techniques have always been thought to structure the matter at the nanometer scale, but combining them with doping methods made it possible to generate local growth of several types of nanocrystals in different kinds of silicate matrices. This paper summarizes the most recent works developed in our group, where the investigated nanoparticles are either made of metal (gold) or chalcogenide semiconductors (CdS, PbS), grown in precursor-impregnated porous xerogels under different laser irradiations. This review is associated to new results on silver nanocrystals in the same kind of matrices. It is shown that, depending on the employed laser, the particles can be formed near the sample surface or deep inside the silica matrix. Photothermal and/or photochemical mechanisms may be invoked to explain the nanoparticle growth, depending on the laser, precursor, and matrix. One striking result is that metal salt reduction, necessary to the production of the corresponding nanoparticles, can efficiently occur due to the thermal wrenching of electrons from the matrix itself or due to multiphoton absorption of the laser light by a reducer additive in femtosecond regime. Very localized semiconductor quantum dots could also be generated using ultrashort pulses, but while PbS nanoparticles grow faster than CdS particles due to one-photon absorption, this better efficiency is counterbalanced by a sensitivity to oxidation. In most cases where the reaction efficiency is high, particles larger than the pores have been obtained, showing that a fast diffusion of the species through the interconnected porosity can modify the matrix itself. Based on our experience in these techniques, we compare several examples of laser-induced nanocrystal growth in porous silica xerogels, which allows

  4. Laser-induced growth of nanocrystals embedded in porous materials

    NASA Astrophysics Data System (ADS)

    Capoen, Bruno; Chahadih, Abdallah; El Hamzaoui, Hicham; Cristini, Odile; Bouazaoui, Mohamed

    2013-06-01

    Space localization of the linear and nonlinear optical properties in a transparent medium at the submicron scale is still a challenge to yield the future generation of photonic devices. Laser irradiation techniques have always been thought to structure the matter at the nanometer scale, but combining them with doping methods made it possible to generate local growth of several types of nanocrystals in different kinds of silicate matrices. This paper summarizes the most recent works developed in our group, where the investigated nanoparticles are either made of metal (gold) or chalcogenide semiconductors (CdS, PbS), grown in precursor-impregnated porous xerogels under different laser irradiations. This review is associated to new results on silver nanocrystals in the same kind of matrices. It is shown that, depending on the employed laser, the particles can be formed near the sample surface or deep inside the silica matrix. Photothermal and/or photochemical mechanisms may be invoked to explain the nanoparticle growth, depending on the laser, precursor, and matrix. One striking result is that metal salt reduction, necessary to the production of the corresponding nanoparticles, can efficiently occur due to the thermal wrenching of electrons from the matrix itself or due to multiphoton absorption of the laser light by a reducer additive in femtosecond regime. Very localized semiconductor quantum dots could also be generated using ultrashort pulses, but while PbS nanoparticles grow faster than CdS particles due to one-photon absorption, this better efficiency is counterbalanced by a sensitivity to oxidation. In most cases where the reaction efficiency is high, particles larger than the pores have been obtained, showing that a fast diffusion of the species through the interconnected porosity can modify the matrix itself. Based on our experience in these techniques, we compare several examples of laser-induced nanocrystal growth in porous silica xerogels, which allows

  5. Lasers.

    ERIC Educational Resources Information Center

    Schewe, Phillip F.

    1981-01-01

    Examines the nature of laser light. Topics include: (1) production and characteristics of laser light; (2) nine types of lasers; (3) five laser techniques including holography; (4) laser spectroscopy; and (5) laser fusion and other applications. (SK)

  6. Optimization of laser-produced plasmas for nanolithography and materials detection

    NASA Astrophysics Data System (ADS)

    Freeman, Justin R.

    In this work, laser-matter interactions and resultant plasma emission using traditional short pulsed lasers are studied in the context of semiconductor lithography and material sensing applications. Ultrafast laser ablation and plasma emission results are then compared to those using traditional short pulsed lasers. Then fundamental laser-matter interactions and ablation processes of ultrafast lasers are investigated. This work focuses on laser-produced plasma (LPP) light sources at extreme ultraviolet (EUV) wavelengths. The out-of-band (OoB) light emission as well as ionic and atomic debris from the plasma source, which are capable of damaging collection optics, have been studied as a function of incident laser wavelength to characterize the angular distributions of debris and identify the differences in debris from longer and shorter laser excitation wavelengths. By applying a prepulse to create improved laser-target coupling conditions, conversion efficiency (CE) from laser energy to 13.5 nm light emission from the plasma source can be improved by 30% or higher. Energetic ions escaping from the plasma can cause significant damage to light collection optics, greatly reducing their lifetimes, but by implementing a prepulse, it has been shown that most-probable ion energies can be reduced significantly, minimizing damage caused to collection optics. Laser-induced breakdown spectroscopy (LIBS) is a technique used to identify the elemental constituents of unknown samples by studying the optical light spectra emitted from a LPP. Despite advantages such as in situ capabilities and near-instant results, detection limits of LIBS systems are not as competitive as other laboratory-based systems. To overcome such limitations, a double pulse (DP) LIBS system is arranged using a long-wavelength laser for the second pulse and heating of the plume created by the first pulse. Detector gating parameters were optimized and different first-pulse laser energies were investigated to

  7. Shock wave and material vapour plume propagation during excimer laser ablation of aluminium samples

    NASA Astrophysics Data System (ADS)

    Jeong, S. H.; Greif, R.; Russo, R. E.

    1999-10-01

    A probe beam deflection technique was utilized to measure the propagation of a shock wave and material vapour plume generated during excimer laser ablation of aluminium samples. The measured transit time of the laser-induced shock wave was compared with the prediction based on an ideal blast-wave model, using the Sedov-Taylor solution. The prediction of the incident laser energy converted into the laser-induced gasdynamic flow utilizing this blast-wave model overestimated the efficiency, even under conditions when the measured shock-wave velocity follows the correct model relation. The propagation of material vapour was measured from the deflection of the probe beam at later times. The propagation velocity of material vapour ranged from 20-40 m s-1 with a greater velocity near the target surface.

  8. Laser printing and femtosecond laser structuring of electrode materials for the manufacturing of 3D lithium-ion micro-batteries

    NASA Astrophysics Data System (ADS)

    Smyrek, P.; Kim, H.; Zheng, Y.; Seifert, H. J.; Piqué, A.; Pfleging, W.

    2016-04-01

    Recently, three-dimensional (3D) electrode architectures have attracted great interest for the development of lithium-ion micro-batteries applicable for Micro-Electro-Mechanical Systems (MEMS), sensors, and hearing aids. Since commercial available micro-batteries are mainly limited in overall cell capacity by their electrode footprint, new processing strategies for increasing both capacity and electrochemical performance have to be developed. In case of such standard microbatteries, two-dimensional (2D) electrode arrangements are applied with thicknesses up to 200 μm. These electrode layers are composed of active material, conductive agent, graphite, and polymeric binder. Nevertheless, with respect to the type of active material, the active material to conductive agent ratio, and the film thickness, such thick-films suffer from low ionic and electronic conductivities, poor electrolyte accessibility, and finally, limited electrochemical performance under challenging conditions. In order to overcome these drawbacks, 3D electrode arrangements are under intense investigation since they allow the reduction of lithium-ion diffusion pathways in between inter-digitated electrodes, even for electrodes with enhanced mass loadings. In this paper, we present how to combine laser-printing and femtosecond laser-structuring for the development of advanced 3D electrodes composed of Li(Ni1/3Mn1/3Co1/3)O2 (NMC). In a first step, NMC thick-films were laser-printed and calendered to achieve film thicknesses in the range of 50 μm - 80 μm. In a second step, femtosecond laser-structuring was carried out in order to generate 3D architectures directly into thick-films. Finally, electrochemical cycling of laser-processed films was performed in order to evaluate the most promising 3D electrode designs suitable for application in long life-time 3D micro-batteries.

  9. A general continuum approach to describe fast electronic transport in pulsed laser irradiated materials: the problem of Coulomb explosion

    NASA Astrophysics Data System (ADS)

    Bulgakova, Nadezhda M.; Stoian, Razvan; Rosenfeld, Arkadi; Marine, Wladimir; Campbell, Eleanor E.

    2004-09-01

    We present a continuum model, based on a drift-diffusion approach, aimed to describe the dynamics of electronic excitation, heating and charge-carrier transport in different materials (metals, semiconductors, and dielectrics) under femtosecond and nanosecond pulsed laser irradiation. The laser-induced charging of the targets is investigated at laser intensities above the material removal threshold. It is demonstrated that, under near-infrared femtosecond irradiation regimes, charging of dielectric surfaces causes a sub-picosecond electrostatic rupture of the superficial layers, alternatively called Coulomb explosion (CE), while this effect is strongly inhibited for metals and semiconductors as a consequence of superior carrier transport properties. On the other hand, simulations of UV nanosecond pulsed laser interaction with bulk silicon have pointed out the possibility of Coulomb explosion in semiconductors. For such regimes a simple analytical theory for the threshold laser fluence of CE has been developed, showing results in agreement with the experimental observations. Various related aspects concerning the possibility of CE depending on different irradiation parameters (fluence, wavelength and pulse duration) are discussed. This includes the temporal and spatial dynamics of charge-carrier generation in non-metallic targets and evolution of the reflection and absorption characteristics.

  10. Laser-Generated Thermoelastic Acoustic Sources in Anisotropic Materials

    SciTech Connect

    David H. Hurley

    2004-05-01

    An analytical model appropriate for thermoelastic generation of acoustic waves in anisotropic materials is presented for both plane and line sources. The interaction of acoustic waves produced by subsurface sources with the bounding surface is accounted for using a method of images. For the plane source case, analytical solutions are found that form an appropriate basis for an angular spectrum of plane waves. For the line source case and for specific crystal symmetries and source orientations, it is shown in the limit of strong optical absorption, a buried line source is equivalent to applying a shear stress dipole at the bounding surface. However, contrary to the isotropic case, the character and strength of the equivalent surface stress is a function of propagation direction.

  11. Researchers at Work: Assessing Needs for Content and Presentation of Archival Materials

    ERIC Educational Resources Information Center

    Allison-Bunnell, Jodi; Yakel, Elizabeth; Hauck, Janet

    2011-01-01

    In the past, systems that present digitized archival materials were often created with limited knowledge of their audiences' needs and greater focus on the materials. Organizations must ask whether digital delivery systems are sufficiently effective to merit financial support. As part of the planning process for a digital delivery system at the…

  12. Space environmental effects, materials, and NDE/NDI presentation to SSTAC/ARTS Review Committee

    NASA Technical Reports Server (NTRS)

    Venneri, Samuel L.

    1991-01-01

    Viewgraphs are presented on space environmental effects, materials, and NDE/NDI for the integrated technology plan for the civil space program. Topics covered include: space materials; space durable polymers; simulated space environmental effects; space radiation effects on polymer matrix composites; advanced coatings for spacecraft; Long Duration Exposure Facility; meteoroid and debris velocity distribution; and space environmental effects.

  13. Tools for Authoring and Presenting Structured Teaching Material in the WWW.

    ERIC Educational Resources Information Center

    Pimentel, Maria da Graca Campos; dos Santos, Joao Benedito, Jr.; de Mattos Fortes, Renata Pontin

    This paper presents aspects of modeling, authoring, and presenting structured documents corresponding to teaching material presented in the World Wide Web. In this context, the importance of providing the formalization of the structure of the documents using Standard Generalized Markup Language (SGML) is discussed. Next, specifications for…

  14. Direct writing of electronic materials using a new laser-assisted transfer/annealing technique

    NASA Astrophysics Data System (ADS)

    Pique, Alberto; Fitz-Gerald, J. M.; Chrisey, Douglas B.; Auyeung, Raymond C. Y.; Wu, H. D.; Lakeou, Samuel; McGill, Robert A.

    2000-06-01

    MAPLE direct write is anew laser-based direct write technique which combines the basic approach employed in laser induced forward transfer with the unique advantages of matrix assisted pulsed laser evaporation. The technique utilizes a laser transparent donor substrate with one side coated with a matrix consisting of the electronic material to be transferred mixed with an organic binder or vehicle. As with LIFT, the laser is focused through the transparent substrate onto the matrix coating. When a laser pulse strikes the coating, the matrix is transferred to an acceptor substrate placed parallel to the donor surface. Ex situ thermal or laser treatments can be used to decompose the matrix and anneal the transferred material, thus forming structures with the desired electronic properties. MAPLE DW is a maskless deposition process designed to operate in air and at room temperature that allows for the generation of complex patterns with micron scale linewidths. The various structures produced by MAPLE DW were characterized using 3D surface profilometry, scanning electron microscopy and optical microscopy. The electrical resistivity of the silver metal lines made by MAPLE DW was measured using an impedance analyzer. Patterns with Zn2SiO4:Mn powders were fabricated over the surface of a dragon fly wing without damaging it. An overview of the key elements of the MAPLE DW process including our current understanding of the material transfer mechanisms and its potential as a rapid prototyping technique will be discussed.

  15. Fires of endotracheal tubes of three different materials during carbon dioxide laser surgery.

    PubMed

    Lai, Hui-Chin; Juang, Sin-Ei; Liu, Tsun-Jui; Ho, Wai-Ming

    2002-03-01

    The hazards of fire during CO2 laser surgery of the airway necessitate the use of special endotracheal tubes. We reviewed 227 cases receiving CO2 laser laryngeal surgery over the past 7 years, of whom 3 suffered the complications as a result of endotracheal fire. Tracheal tubes made of different materials were used among them, including silicone T-tube (Montgomery Safe-T-tube), jet ventilation tube and Xomed laser shield endotracheal tube. In addition, we tested in vitro the combustibility of endotracheal tubes of six different materials which included silicone T-tube, jet ventilation tube, Xomed laser shield endotracheal tube, stainless Laser-Flex tracheal tube, polyvinyl chloride (PVC) endotracheal tube and aluminum foil wrapped PVC endotracheal tube by exposing them to continuous operating CO2 laser in room air. The time to initiation of fire and burn through the lumen was 0.3 second for T-tube, 0.5 s for jet ventilation tube, 5 s for Xomed laser shield endotracheal tube, and 0.8 s for PVC endotracheal tube, respectively. The Laser-Flex tracheal tube (stainless) and aluminum foil wrapped PVC endotracheal tube did not catch fire after 30 s of CO2 laser irradiation. The silicone T-tube seemed to be the most dangerous. Jet ventilation tube and Xomed laser shield endotracheal tube have the risk of fire. Aluminum foil wrapped PVC endotracheal tube was reported to catch fire before. Therefore we are of the opinion that the stainless endotracheal tube is the safest tube during CO2 laser surgery. PMID:11989049

  16. Innovation Study for Laser Cutting of Complex Geometries with Paper Materials

    NASA Astrophysics Data System (ADS)

    Happonen, A.; Stepanov, A.; Piili, H.; Salminen, A.

    Even though technology for laser cutting of paper materials has existed for over 30 years, it seems that results of applications of this technology and possibilities of laser cutting systems are not easily available. The aim of this study was to analyze the feasibility of the complex geometry laser cutting of paper materials and to analyze the innovation challenges and potential of current laser cutting technologies offer. This research studied the potential and possible challenges in applying CO2 laser cutting technology for cutting of paper materials in current supply chains trying to fulfil the changing needs of customer in respect of shape, fast response during rapid delivery cycle. The study is focused on examining and analyzing the different possibilities of laser cutting of paper material in application area of complex low volume geometry cutting. The goal of this case was to analyze the feasibility of the laser cutting from technical, quality and implementation points of view and to discuss availability of new business opportunities. It was noticed that there are new business models still available within laser technology applications in complex geometry cutting. Application of laser technology, in business-to-consume markets, in synergy with Internet service platforms can widen the customer base and offer new value streams for technology and service companies. Because of this, existing markets and competition has to be identified, and appropriate new and innovative business model needs to be developed. And to be competitive in the markets, models like these need to include the earning logic and the stages from production to delivery as discussed in the paper.

  17. Laser based ultrasound using different wavelengths for the inspection of composite materials

    NASA Astrophysics Data System (ADS)

    Stratoudaki, T.; Edwards, C.; Dixon, S.; Palmer, S. B.

    2002-05-01

    This paper investigates damage free ultrasound generation on Carbon Fiber Reinforced Composites using a range of different lasers: TEA CO2 (10.6 μm), Nd:YAG (1064 nm) and a XeCl excimer laser (308 nm). It is essential that no damage is caused to the components and this restricts generation to the thermoelastic regime, where it is due to rapid thermal expansion. For this reason, the laser damage thresholds of the samples are presented and compared.

  18. Energy consumption in personal computer attached laser printers: Past, present, future

    SciTech Connect

    Green, T.

    1995-12-01

    Personal computer (PC) printers have been criticized in recent years for their energy consumption, with criticism especially targeted at laser printers. The popular view, largely correct, has been that inkjet printers were energy-efficient, while lasers were power {open_quotes}hogs.{close_quotes} it will be shown, however, that laser printer energy consumption has dramatically improved in the last few years, thanks largely to prompting by the U.S. Environmental Protection Agency`s (EPA`s) Energy Star program. Two years ago laser printers idled drawing 70 to 100 W; most now idle drawing 5 to 30 W. The inkjet printer`s energy efficiency has been widely publicized, so it will be used as a benchmark throughout this paper. When idle, an inkjet printer draws 5 to 10 W. Some laser printers` total energy consumption has now dropped to a level such that their energy consumption, for similar performance machines, now approaches that of inkjet printers.

  19. Application of laser ultrasonics to monitor material degradation in FRP composites

    NASA Astrophysics Data System (ADS)

    Dokun, Olajide D.; Jacobs, Laurence J.; Haj-Ali, Rami M.

    2000-05-01

    This research uses laser ultrasonic techniques to monitor frequency dependent Rayleigh phase velocity (material dispersion) and then relates changes in this acoustic property to changes in the material's properties (such as stiffness) that characterize damage. The subject material system is a thick, glass reinforced, vinylester (thermosetting) FRP composite. Laser ultrasonics is an ideal methodology to monitor changes in the Rayleigh phase velocity of this material because of its high fidelity, broad bandwidth, point source/receiver, and noncontact nature. The experimental procedure consists of measuring a series of transient elastic waveforms in a thick FRP specimen and then operating on these waveforms with the 2D-FFT to develop the (material) dispersion relationship for that specimen. Material degradation (damage) is introduced into these specimens with environmental aging and mechanical loading, and the dispersion curves are used to quantitatively track changes in material properties as a function of degradation.

  20. ICALEO '91 - Laser materials processing; Proceedings of the Meeting, San Jose, CA, Nov. 3-8, 1991

    NASA Astrophysics Data System (ADS)

    Metzbower, Edward A.; Beyer, Eckhard; Matsunawa, Akira

    Consideration is given to new developments in LASERCAV technology, modeling of deep penetration laser welding, the theory of radiative transfer in the plasma of the keyhole in penetration laser welding, a synchronized laser-video camera system study of high power laser material interactions, laser process monitoring with dual wavelength optical sensors, new devices for on-line process diagnostics during laser machining, and the process development for a portable Nd:YAG laser materials processing system. Attention is also given to laser welding of alumina-reinforced 6061 aluminum alloy composite, the new trend of laser materials processing, optimization of the laser cutting process for thin section stainless steels, a new nozzle concept for cutting with high power lasers, rapid solidification effects during laser welding, laser surface modification of a low carbon steel with tungsten carbide and carbon, absorptivity of a polarized beam during laser hardening, and laser surface melting of 440 C tool steel. (No individual items are abstracted in this volume)

  1. Comparative study of laser induced breakdown spectroscopy and mass spectrometry for the analysis of cultural heritage materials

    NASA Astrophysics Data System (ADS)

    Kokkinaki, O.; Mihesan, C.; Velegrakis, M.; Anglos, D.

    2013-07-01

    Analysis by laser-induced breakdown spectroscopy (LIBS) is compared, on the basis of a hybrid experimental set-up, with laser ablation time-of-flight mass spectrometry (LA-TOF-MS) for the characterization of materials relevant to cultural heritage. The present study focuses on the analysis of selected paint materials such as lithopone, a white inorganic pigment, and two synthetic organic paint formulations, lemon yellow and phthalocyanine blue. Optical emission spectra, obtained by LIBS, lead to rapid, straightforward identification of the elemental content of the paint samples while mass spectra yield, additionally to elemental analysis, complementary isotopic analysis and, more importantly, enable detection of molecules and molecular fragments, permitting a more complete structural and compositional characterization of composite materials. Mass spectra were recorded either simultaneously with the optical emission ones, or sequentially. The latter was preferred for materials having significantly lower fluence threshold for desorption/ionization relative to plasma formation resulting to optimum mass resolution and minimal surface damage. In all, the results of this study demonstrate the advantages of instrumentally complementing LIBS with TOF-MS in relation to applications in cultural heritage materials analysis, with exciting prospects when laser ablation sampling can be carried out under ambient atmosphere.

  2. Double-pulse standoff laser-induced breakdown spectroscopy for versatile hazardous materials detection

    NASA Astrophysics Data System (ADS)

    Gottfried, Jennifer L.; De Lucia, Frank C.; Munson, Chase A.; Miziolek, Andrzej W.

    2007-12-01

    We have developed a double-pulse standoff laser-induced breakdown spectroscopy (ST-LIBS) system capable of detecting a variety of hazardous materials at tens of meters. The use of a double-pulse laser improves the sensitivity and selectivity of ST-LIBS, especially for the detection of energetic materials. In addition to various metallic and plastic materials, the system has been used to detect bulk explosives RDX and Composition-B, explosive residues, biological species such as the anthrax surrogate Bacillus subtilis, and chemical warfare simulants at 20 m. We have also demonstrated the discrimination of explosive residues from various interferents on an aluminum substrate.

  3. Picosecond laser ultrasonics for imaging of transparent polycrystalline materials compressed to megabar pressures.

    PubMed

    Kuriakose, Maju; Raetz, Samuel; Chigarev, Nikolay; Nikitin, Sergey M; Bulou, Alain; Gasteau, Damien; Tournat, Vincent; Castagnede, Bernard; Zerr, Andreas; Gusev, Vitalyi E

    2016-07-01

    Picosecond laser ultrasonics is an all-optical experimental technique based on ultrafast high repetition rate lasers applied for the generation and detection of nanometric in length coherent acoustic pulses. In optically transparent materials these pulses can be detected not only on their arrival at the sample surfaces but also all along their propagation path inside the sample providing opportunity for imaging of the sample material spatial inhomogeneities traversed by the acoustic pulse. Application of this imaging technique to polycrystalline elastically anisotropic transparent materials subject to high pressures in a diamond anvil cell reveals their significant texturing/structuring at the spatial scales exceeding dimensions of the individual crystallites.

  4. Spectroscopic properties and laser performances of Yb:YCOB and potential of the Yb:LaCOB material

    NASA Astrophysics Data System (ADS)

    Aron, A.; Aka, G.; Viana, B.; Kahn-Harari, A.; Vivien, D.; Druon, F.; Balembois, F.; Georges, P.; Brun, A.; Lenain, N.; Jacquet, M.

    2001-02-01

    In order to increase the compacity of the Yb-doped lasers, YCOB (Ca 4Y(BO 3) 3) materials with high ytterbium concentration have been characterized. Large 15 at.% and 35 at.% ytterbium-doped single crystals were grown by the Czochralski pulling method. Spectroscopic and laser properties have been investigated and laser tests performed under titanium sapphire and diode pumping at 976 nm. Low thresholds under Ti:Sa pumping (50 mW) and high slope efficiency under diode pumping (66%) have been obtained. The optical quality and the distribution of Yb 3+ dopant through the highly doped crystals is discussed. First results on the Yb:LaCOB crystals grown by the Czochralski process, containing 46Yb 3+ at.%, are also presented.

  5. Detecting Partial Energy Modulation in a Dielectric Laser Accelerator - Oral Presentation

    SciTech Connect

    Lukaczyk, Louis

    2015-08-24

    The Dielectric Laser Acceleration group at SLAC uses micro-fabricated dielectric grating structures and conventional infrared lasers to accelerator electrons. These structures have been estimated to produce an accelerating gradient up to 2 orders of magnitude greater than that produced by conventional RF accelerators. The success of the experiment depends on both the laser damage threshold of the structure and the timing overlap of femtosecond duration laser pulses with the electron bunch. In recent dielectric laser acceleration experiments, the laser pulse was shorter both temporally and spatially than the electron bunch. As a result, the laser is theorized to have interacted with only a small portion of the electron bunch. The detection of this phenomenon, referred to as partial population modulation, required a new approach to the data analysis of the electron energy spectra. A fitting function was designed to separate the accelerated electron population from the unaccelerated electron population. The approach was unsuccessful in detecting acceleration in the partial population modulation data. However, the fitting functions provide an excellent figure of merit for previous data known to contain signatures of acceleration.

  6. Lasers '85; Proceedings of the Eighth International Conference, Las Vegas, NV, Dec. 2-6, 1985

    SciTech Connect

    Wang, C.P.

    1986-01-01

    The present conference on laser technology development encompasses issues in such areas as VUV and X-ray lasers; optical phase conjugation and nonlinear optics; laser applications in medicine; methods for optical processing; laser and nonlinear spectroscopy; ultrashort-pulse lasers and their applications; frequency selection in pulsed lasers; and interactions between laser beams, material surfaces, and material volumes. Also treated are laser applications in the Strategic Defense Initiative program, chemical laser design and performance, the lasing of biophysical materials, laser diagnostics in fluids and plasma, semiconductor laser diodes and arrays, solid state lasers, radiation- and solar-pumped lasers, laser cavities and propagation, remote sensing with lasers and fiber-optics, coupled resonators and diode lasers, industrial applications of lasers, excimer lasers, optoelectronics, CO/sub 2/ lasers, fiber-optic sensors, alexandrite lasers, free electron lasers, and IR and visible wavelength lasers.

  7. Research on ultrasonic vibration aided femtosecond laser machining process of transparent materials

    NASA Astrophysics Data System (ADS)

    Dai, Yutang; Liu, Bin; Yin, Guanglin; Li, Tao; Karanja, Joseph M.

    2015-08-01

    A new process of femtosecond laser micromachining with ultrasonic vibration aided is proposed. An ultrasonic aided device has been designed, and the laser micromachining experiments of transparent materials have been carried out. The effects of the ultrasonic vibration with different power on surface quality and the drilling depth have been investigated, and the mechanism of the ultrasonic vibration aided laser machining has been analyzed. After introducing the ultrasonic vibration device, the residue debris on surface of the ablated trench is significantly reduced, and the drilling depth is increased. These results show that, ultrasonic vibration can effectively improve the surface quality of material processing, increase the depth of the drilling hole and promote the processing efficiency of the femtosecond laser.

  8. Ultrafast laser diagnostics for understanding hot spot initiation in energetic materials

    NASA Astrophysics Data System (ADS)

    Kohl, Ian; Farrow, Darcie; Kearney, Sean; Knepper, Robert; Kay, Jeffrey

    Ultrafast laser diagnostics have opened new pathways for investigation of shock physics and initiation of energetic materials. Recent work (Bolme LANL/Armstrong LLNL) has demonstrated that short laser pulses can be utilized for direct laser drive and coupled with imaging, spectroscopic, and interferometric tools for studies of dynamic shock loading on picosecond time scales. At Sandia, we are developing diagnostic platforms which extend this earlier work by combining Ultrafast Shock Interferometry (USI) (Armstrong LLNL) and femtosecond transient absorption spectroscopy for tabletop measurement of Hugoniot/Equation-of-state data and characterization of shock structure in heterogeneous materials with micron spatial resolution while probing shock-induced changes in the electronic structure, which have been proposed to drive rapid chemical changes behind the shock front. We will describe the details of our measurement systems, as well as recent progress toward new laser-diagnostic data on inert/explosive thin-film samples.

  9. Microstructures and properties of materials under repeated laser irradiation

    SciTech Connect

    Averback, Robert; Bellon, Pascal

    2007-02-12

    This research program has explored the stability of alloys under pulsed laser irradiation. Two primary directions were investigated: (i) phase transitions during a single laser pulse, and (ii) phase stability under repeated laser irradiation. The first theme was primarily concerned with both the crystalline to amorphous phase transition and the transition of liquids and glasses to crystalline matter. The second project examined the phase evolution during laser pulsing in situations where plastic deformation was prevalent (high-energy laser pulses). Both computer simulation and experimental programs were undertaken. Our work using computer simulations had several notable successes. For the work connected with multiple pulsing, we used molecular dynamics (MD) to simulate the behavior of alloys under severe plastic deformation. We found that during high strain-rate deformation atomic mixing of chemical species is random, independent of the detailed thermochemical properties of the system. This result contrasts with recent reports. In this work, we also developed two new methods of analyzing atomic mixing, one is based on relative mean square displacements (RMSD) of atoms and the other, Burgers vector analysis (BVA), on nearest neighbor displacements. The RMSD analysis is valuable in that it specifies the length scales over which deformation processes take place, and we applied it to understand deformation in nanocrystalline, amorphous and large-grained systems. The BVA analysis, on the other hand, reveals if the damage is homogeneous. Finally we showed that at elevated temperatures, the phase stability is not determined from a simple competition between shearing events and vacancy diffusion, which has long been assumed, but rather atomic mixing in the shearing events is temperature dependent. This work is significant in that it elucidates the fundamental mechanisms that underlie high strain rate deformation, and it provides computational tools for other researchers to

  10. Relevance of the choice of diagnostic methods to investigate laser damage resistance in optical material

    NASA Astrophysics Data System (ADS)

    Natoli, Jean-Yves; Wagner, Frank; Gallais, Laurent; Commandré, Mireille

    2012-01-01

    Laser induced damage in optical material in nanosecond regime is widely attributed to local precursors in range of nanometer to micrometer size. The damage precursors nature strongly depends on materials (coatings, non linear crystals, substrates,..), breakdown location (bulk, surface, interface) and irradiation parameters (wavelength, pulse duration...). The weakness of knowledge on parameters as sizes, densities and natures of precursors, let think that the choice of the diagnostic method which reveals laser damage has to be adapted to each situation of irradiation. Concerning the LIDT determination, destructive methods are usually involved: we can cite full size test using the "real" final configuration of irradiation, raster scan method using a focused laser beam allowing laboratory test and statistic approach allowing study with different beam sizes in order to probe the material homogeneity in terms of precursors. This multi-scale approaches give relevant information on material properties regarding high power laser irradiation. In order to investigate the laser damage initiation mechanisms, it appears necessary to involve non-destructive diagnostics. These diagnostics permit to highlight modifications linked to precursors before material breakdown. The main difficulty here is the local character of the diagnostic added to the low density of initiating center. A multi-scale approach is thus also well adapted to the non-destructive case. Interest of diagnostics as local fluorescence and photothermal deflexion both correlated with LIDT results will be discussed. To illustrate the purpose, examples on non linear crystals and coatings will be shown.

  11. Relevance of the choice of diagnostic methods to investigate laser damage resistance in optical material

    NASA Astrophysics Data System (ADS)

    Natoli, Jean-Yves; Wagner, Frank; Gallais, Laurent; Commandré, Mireille

    2011-11-01

    Laser induced damage in optical material in nanosecond regime is widely attributed to local precursors in range of nanometer to micrometer size. The damage precursors nature strongly depends on materials (coatings, non linear crystals, substrates,..), breakdown location (bulk, surface, interface) and irradiation parameters (wavelength, pulse duration...). The weakness of knowledge on parameters as sizes, densities and natures of precursors, let think that the choice of the diagnostic method which reveals laser damage has to be adapted to each situation of irradiation. Concerning the LIDT determination, destructive methods are usually involved: we can cite full size test using the "real" final configuration of irradiation, raster scan method using a focused laser beam allowing laboratory test and statistic approach allowing study with different beam sizes in order to probe the material homogeneity in terms of precursors. This multi-scale approaches give relevant information on material properties regarding high power laser irradiation. In order to investigate the laser damage initiation mechanisms, it appears necessary to involve non-destructive diagnostics. These diagnostics permit to highlight modifications linked to precursors before material breakdown. The main difficulty here is the local character of the diagnostic added to the low density of initiating center. A multi-scale approach is thus also well adapted to the non-destructive case. Interest of diagnostics as local fluorescence and photothermal deflexion both correlated with LIDT results will be discussed. To illustrate the purpose, examples on non linear crystals and coatings will be shown.

  12. Liquid-assisted laser ablation of advanced ceramics and glass-ceramic materials

    NASA Astrophysics Data System (ADS)

    Garcia-Giron, A.; Sola, D.; Peña, J. I.

    2016-02-01

    In this work, results obtained by laser ablation of advanced ceramics and glass-ceramic materials assisted by liquids are reported. A Q-switched Nd:YAG laser at its fundamental wavelength of 1064 nm with pulse-width in the nanosecond range was used to machine the materials, which were immersed in water and ethylene glycol. Variation in geometrical parameters, morphology, and ablation yields were studied by using the same laser working conditions. It was observed that machined depth and removed volume depended on the thermal, optical, and mechanical features of the processed materials as well as on the properties of the surrounding medium in which the laser processing was carried out. Variation in ablation yields was studied in function of the liquid used to assist the laser process and related to refractive index and viscosity. Material features and working conditions were also related to the obtained results in order to correlate ablation parameters with respect to the hardness of the processed materials.

  13. A new analytical approach for heat generation in tissue due to laser excitation (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Erkol, Hakan; Nouizi, Farouk; Luk, Alex T.; Unlu, Mehmet B.; Gulsen, Gultekin

    2016-03-01

    In this study, we present a fast analytical approach for laser induced temperature increase in biological tissue. The whole problem consists of two main steps. These steps are the light propagation and heat transfer in tissue. We first obtain a detailed analytical solution for the diffusion equation based on an integral approach for specific boundary conditions. Secondly, we also solve the Pennes' bio-heat transfer equation analytically using the separation of variables technique and obtain the temperature induced by optical absorption of tissue. Here, heat source term consists of the local absorption and photon density, which will be determined from the diffusion equation. We find a very comprehensive solution for the diffusion equation by using an integral method for the Robin boundary condition. In other words, we obtain a particular Green's function in a different way. Next, we use this solution as a source term in the Pennes' bio-heat equation by utilizing the heat convection boundary condition. It is important to note that these boundary conditions are good approximations for imaging of biological tissue. As a result, we obtain spatio-temporal temperature distribution inside the medium. First, our approach is validated by a numerical approach using a Finite Element Method (FEM). Next, we also validate our method by performing phantom and tissue experiments. Experimental data corresponding to spatio-temporal temperature distribution are recorded using magnetic resonance thermometry. The analytical results obtained by our method are in a very good agreement with ones obtained by the FEM and experiment.

  14. Computer simulation of the processing of engineering materials with lasers - theory and first applications

    NASA Astrophysics Data System (ADS)

    Gross, M. S.; Black, I.; Müller, W. H.

    2003-04-01

    Current numerical simulations of laser materials processing are usually based on a greatly simplified process model in order to allow for short computation times. This significantly decreases their flexibility and ability for simulation of the great variation of today's processes and, consequently, accounting for their subtle but important differences. The theory utilized for building a simulation tool presented in this paper can be said to be truly three-dimensional as opposed to other reported work that uses symmetric boundary conditions. The interaction of the free surface of the liquid face is modelled which provides a significant increase in the amount of process detail captured. The investigators contend that numerical modelling of the above can only be achieved credibly using high performance computing methods, in particular parallelization techniques.

  15. Analysis of Nickel Based Hardfacing Materials Manufactured by Laser Cladding for Sodium Fast Reactor

    NASA Astrophysics Data System (ADS)

    Aubry, P.; Blanc, C.; Demirci, I.; Dal, M.; Malot, T.; Maskrot, H.

    For improving the operational capacity, the maintenance and the decommissioning of the future French Sodium Fast Reactor ASTRID which is under study, it is asked to find or develop a cobalt free hardfacing alloy and the associated manufacturing process that will give satisfying wear performances. This article presents recent results obtained on some selected nickel-based hardfacing alloys manufactured by laser cladding, particularly on Tribaloy 700 alloy. A process parameter search is made and associated the microstructural analysis of the resulting clads. A particular attention is made on the solidification of the main precipitates (chromium carbides, boron carbides, Laves phases,…) that will mainly contribute to the wear properties of the material. Finally, the wear resistance of some samples is evaluated in simple wear conditions evidencing promising results on tribology behavior of Tribaloy 700.

  16. Laser surgery of zebrafish (Danio rerio) embryos using femtosecond laser pulses: Optimal parameters for exogenous material delivery, and the laser's effect on short- and long-term development

    PubMed Central

    Kohli, Vikram; Elezzabi, Abdulhakem Y

    2008-01-01

    Background Femtosecond (fs) laser pulses have recently received wide interest as an alternative tool for manipulating living biological systems. In various model organisms the excision of cellular components and the intracellular delivery of foreign exogenous materials have been reported. However, the effect of the applied fs laser pulses on cell viability and development has yet to be determined. Using the zebrafish (Danio rerio) as our animal model system, we address both the short- and long-term developmental changes following laser surgery on zebrafish embryonic cells. Results An exogenous fluorescent probe, fluorescein isothiocyanate (FITC), was successfully introduced into blastomere cells and found to diffuse throughout all developing cells. Using the reported manipulation tool, we addressed whether the applied fs laser pulses induced any short- or long-term developmental effects in embryos reared to 2 and 7 days post-fertilization (dpf). Using light microscopy and scanning electron microscopy we compared key developmental features of laser-manipulated and control samples, including the olfactory pit, dorsal, ventral and pectoral fins, notochord, pectoral fin buds, otic capsule, otic vesicle, neuromast patterning, and kinocilia of the olfactory pit rim and cristae of the lateral wall of the ear. Conclusion In our study, no significant differences in hatching rates and developmental morphologies were observed in laser-manipulated samples relative to controls. This tool represents an effective non-destructive technique for potential medical and biological applications. PMID:18230185

  17. Method and apparatus for optimizing the efficiency and quality of laser material processing

    DOEpatents

    Susemihl, I.

    1990-03-13

    The efficiency of laser welding and other laser material processing is optimized according to this invention by rotating the plane of polarization of a linearly polarized laser beam in relation to a work piece of the material being processed simultaneously and in synchronization with steering the laser beam over the work piece so as to keep the plane of polarization parallel to either the plane of incidence or the direction of travel of the beam in relation to the work piece. Also, depending to some extent on the particular processing being accomplished, such as welding or fusing, the angle of incidence of the laser beam on the work piece is kept at or near the polarizing or Brewster's angle. The combination of maintaining the plane of polarization parallel to plane of incidence while also maintaining the angle of incidence at or near the polarizing or Brewster's angle results in only minimal, if any, reflection losses during laser welding. Also, coordinating rotation of the plane of polarization with the translation or steering of a work piece under a laser cutting beam maximizes efficiency and kerf geometry, regardless of the direction of cut. 7 figs.

  18. Method and apparatus for optimizing the efficiency and quality of laser material processing

    DOEpatents

    Susemihl, Ingo

    1990-01-01

    The efficiency of laser welding and other laser material processing is optimized according to this invention by rotating the plane of polarization of a linearly polarized laser beam in relation to a work piece of the material being processed simultaneously and in synchronization with steering the laser beam over the work piece so as to keep the plane of polarization parallel to either the plane of incidence or the direction of travel of the beam in relation to the work piece. Also, depending to some extent on the particular processing being accomplished, such as welding or fusing, the angle of incidence of the laser beam on the work piece is kept at or near the polarizing or Brewster's angle. The combination of maintaining the plane of polarization parallel to plane of incidence while also maintaining the angle of incidence at or near the polarizing or Brewster's angle results in only minimal, if any, reflection losses during laser welding. Also, coordinating rotation of the plane of polarization with the translation or steering of a work piece under a laser cutting beam maximizes efficiency and kerf geometry, regardless of the direction of cut.

  19. Laser welding of dissimilar materials for lightweight construction and special applications

    NASA Astrophysics Data System (ADS)

    Schimek, Mitja; Springer, André; Pfeifer, Ronny; Kaierle, Stefan

    2013-02-01

    Against the background of climate objectives and the desired reduction of CO2-emissions, optimization of existing industrial products is needed. To counter rising raw material costs, currently used materials are substituted. This will places new requirements on joining technologies for dissimilar material classes. The main difficulty lies in joining these materials cohesively without changing the properties of the base materials. Current research work at the LZH on joining dissimilar materials is being carried out for the automotive sector and for solar absorbers. For the automotive industry, a laser welding process for joining steel and aluminum without using additives is being investigated, equipped with a spectroscopic welding depth control to increase tensile strength. With a specially constructed laser processing head, it is possible to regulate welding penetration depth in the aluminum sheet, reducing the formation of intermetallic phases. Flat plate solar collectors are favorable devices for generating heat from solar energy. The solar absorber is the central part of a collector, consisting of an aluminum sheet and a copper tube which is attached to the aluminum sheet. Research on new laser welding processes aims at reducing the amount of energy required for production of these solar absorbers. In the field of joining dissimilar materials, laser joining processes, especially for special applications, will complement established joining techniques.

  20. Ultrafast laser processing of transparent materials supported by in-situ diagnostics

    NASA Astrophysics Data System (ADS)

    Kumkar, M.; Kaiser, M.; Kleiner, J.; Grossmann, D.; Flamm, D.; Bergner, K.; Nolte, S.

    2016-03-01

    For the development of industrial NIR ultrafast laser processing of transparent materials, the absorption inside the bulk material has to be controlled. Applications we aim for are front and rear side ablation, drilling and inscription of modifications for cleaving and selective laser etching of glass and sapphire in sheet geometry. We applied pump probe technology and in situ stress birefringence microscopy for fundamental studies on the influence of energy and duration (100 fs - 20 ps), temporal and spatial spacing, focusing and beam shaping of the laser pulses. Applying pump probe technique we are able to visualize differences of spatio-temporal build up of absorption, self focusing, shock wave generation for standard, multispot and beam shaped focusing. Incubation effects and disturbance of beam propagation due to modifications or ablation can be observed. In-situ imaging of stress birefringence gained insight in transient build up of stress with and without translation. The results achieved so far, demonstrate that transient stress has to be taken into account in scaling the laser machining throughput of brittle materials. Furthermore it points out that transient stress birefringence is a good indicator for accumulation effects, supporting tailored processing strategies. Cutting results achieved for selective laser etching by single pass laser modification exemplifies the benefits of process development supported by in situ diagnostics.

  1. Design and implementation of a system for laser assisted milling of advanced materials

    NASA Astrophysics Data System (ADS)

    Wu, Xuefeng; Feng, Gaocheng; Liu, Xianli

    2016-04-01

    Laser assisted machining is an effective method to machine advanced materials with the added benefits of longer tool life and increased material removal rates. While extensive studies have investigated the machining properties for laser assisted milling(LAML), few attempts have been made to extend LAML to machining parts with complex geometric features. A methodology for continuous path machining for LAML is developed by integration of a rotary and movable table into an ordinary milling machine with a laser beam system. The machining strategy and processing path are investigated to determine alignment of the machining path with the laser spot. In order to keep the material removal temperatures above the softening temperature of silicon nitride, the transformation is coordinated and the temperature interpolated, establishing a transient thermal model. The temperatures of the laser center and cutting zone are also carefully controlled to achieve optimal machining results and avoid thermal damage. These experiments indicate that the system results in no surface damage as well as good surface roughness, validating the application of this machining strategy and thermal model in the development of a new LAML system for continuous path processing of silicon nitride. The proposed approach can be easily applied in LAML system to achieve continuous processing and improve efficiency in laser assisted machining.

  2. CRC handbook of laser science and technology. Volume 3. Optical materials, Part 1 - Nonlinear optical properties/radiation damage

    SciTech Connect

    Weber, M.J.

    1986-01-01

    This book examines the nonlinear optical properties of laser materials. The physical radiation effects on laser materials are also considered. Topics considered include: nonlinear optical properties; nonlinear and harmonic generation materials; two-photon absorption; nonlinear refractive index; stimulated Raman scattering; radiation damage; crystals; and glasses.

  3. Responses of organic and inorganic materials to intense EUV radiation from laser-produced plasmas

    NASA Astrophysics Data System (ADS)

    Makimura, Tetsuya; Torii, Shuichi; Nakamura, Daisuke; Takahashi, Akihiko; Okada, Tatsuo; Niino, Hiroyuki; Murakami, Kouichi

    2013-05-01

    We have investigated responses of polymers to EUV radiation from laser-produced plasmas beyond ablation thresholds and micromachining. We concentrated on fabricate precise 3D micro-structures of PDMS, PMMA, acrylic block copolymers (BCP), and silica. The micromachining technique can be applied to three-dimensional micro-fluidic and bio-medical devices. The EUV processing is a promising to realize a practical micromachining technique. In the present work, we used two EUV radiation sources; (a) Wide band EUV light in a range of 10{300 eV was generated by irradiation of Ta targets with Nd:YAG laser light at 500 mJ/pulse. (b) Narrow band EUV light at 11 and 13 nm was generated by irradiation of solid Xe and Sn targets, respectively, with pulsed TEA CO2 laser light. The generated EUV light was condensed onto the materials at high power density beyond the ablation thresholds, using ellipsoidal mirrors. We found that through-holes with a diameter of one micrometer an be fabricated in PMMA and PDMS sheets with thicknesses of 4-10 micrometers, at 250 and 230 nm/shot, respectively. The effective ablation of PMMA sheets can be applied to a LIGA-like process for fabricating micro-structures of metals for micro- and nano-molds. PDMS sheets are ablated if it is irradiated with EUV light beyond a distinct threshold power density, while PDMS surfaces were modified at lower power densities. Furthermore, BCP sheets were ablated to have 1-micrometer structures. Thus, we have developed a practical technique for micromachining of PMMA, PDMS and BCP sheets in a micrometer scale.

  4. Semiconductor diode laser material and devices with emission in visible region of the spectrum

    NASA Technical Reports Server (NTRS)

    Ladany, I.; Kressel, H.

    1975-01-01

    Two alloy systems, (AlGa)As and (InGa)P, were studied for their properties relevant to obtaining laser diode operation in the visible region of the spectrum. (AlGa)As was prepared by liquid-phase epitaxy (LPE) and (InGa)P was prepared both by vapor-phase epitaxy and by liquid-phase epitaxy. Various schemes for LPE growth were applied to (InGa)P, one of which was found to be capable of producing device material. All the InGaP device work was done using vapor-phase epitaxy. The most successful devices were fabricated in (AlGa)As using heterojunction structures. At room temperature, the large optical cavity design yielded devices lasing in the red (7000 A). Because of the relatively high threshold due to the basic band structure limitation in this alloy, practical laser diode operation is presently limited to about 7300 A. At liquid-nitrogen temperature, practical continuous-wave operation was obtained at a wavelength of 6500 to 6600 A, with power emission in excess of 50 mW. The lowest pulsed lasing wavelength is 6280 A. At 223 K, lasing was obtained at 6770 A, but with high threshold currents. The work dealing with CW operation at room temperature was successful with practical operation having been achieved to about 7800 A.

  5. Electrical and optical study of semiconductor laser diodes and materials

    NASA Technical Reports Server (NTRS)

    Albin, Sacharia

    1987-01-01

    The characterization of a 2-D diode laser array from McDonald Douglas has been completed. The array consisted of 8 linear arrays of approximately 11 mm x 0.18 mm. Each array has between 7 and 8 diodes per mm. The threshold current is approximately 15 amps. The power output vs drive current (above threshold) of the array was measured. A peak power of 50 W was obtained at a drive current of 26 amps. Its far field pattern has a double lobe.

  6. Solid-state tunable lasers based on dye-doped sol-gel materials

    SciTech Connect

    Dunn, B.; Mackenzie, J.D.; Zink, J.I.; Stafsudd, O.M.

    1992-03-01

    The sol-gel process is a solution synthesis technique which provides a low temperature chemical route for the preparation of rigid transparent matrix materials. The luminescent organic dye molecules, rhodamine 6G and coumarin 540A have been incorporated, via the sol-gel method, into aluminosilicate and organically modified silicate host matrices. Synthesis, laser oscillation and photostability for these systems are reported. The improved photostability of these materials with respect to comparable polymeric host materials is discussed.

  7. Study of issues in difficult-to-weld thick materials by hybrid laser arc welding

    NASA Astrophysics Data System (ADS)

    Mazar Atabaki, Mehdi

    There is a high interest for the high strength-to-weight ratio with good ductility for the welds of advanced alloys. The concern about the welding of thick materials (Advanced high strength steels (AHSS) and 5xxx and 6xxx series of aluminum alloys) has stimulated the development of manufacturing processes to overcome the associated issues. The need to weld the dissimilar materials (AHSS and aluminum alloys) is also required for some specific applications in different industries. Hence, the requirement in the development of a state-of-the-art welding procedure can be helpful to fulfill the constraints. Among the welding methods hybrid laser/arc welding (HLAW) has shown to be an effective method to join thick and difficult-to-weld materials. This process benefits from both advantages of the gas metal arc welding (GMAW) and laser welding processes. The interaction of the arc and laser can help to have enough penetration of weld in thick plates. However, as the welding of dissimilar aluminum alloys and steels is very difficult because of the formation of brittle intermetallics the present work proposed a procedure to effectively join the alloys. The reports showed that the explosively welded aluminum alloys to steels have the highest toughness, and that could be used as an "insert" (TRICLAD) for welding the thick plates of AHSS to aluminum alloys. Therefore, the HLAW of the TRICLAD-Flange side (Aluminum alloy (AA 5456)) to the Web side (Aluminum alloys (AA 6061 and AA 5456)) and the TRICLAD-Flange side (ASTM A516) to the Web side (AHSS) was studied in the present work. However, there are many issues related to HLAW of the dissimilar steels as well as dissimilar aluminum alloys that have to be resolved in order to obtain sound welds. To address the challenges, the most recent welding methods for joining aluminum alloys to steels were studied and the microstructural development, mechanical properties, and on-line monitoring of the welding processes were discussed as well

  8. Liquid rocket booster integration study. Volume 4: Reviews and presentation material

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Liquid rocket booster integration study is presented. Volume 4 contains materials presented at the MSFC/JSC/KSC Integrated Reviews and Working Group Sessions, and the Progress Reviews presented to the KSC Study Manager. The following subject areas are covered: initial impact assessment; conflicts with the on-going STS mission; access to the LRB at the PAD; the activation schedule; transition requirements; cost methodology; cost modelling approach; and initial life cycle cost.

  9. Nd:YAG Laser Cleaning of Red Stone Materials: Evaluation of the Damage

    NASA Astrophysics Data System (ADS)

    Colombo, C.; Martoni, E.; Realini, M.; Sansonetti, A.; Valentini, G.

    Lasers have been tested, during the recent past, as a useful cleaning method in conservation treatments: this is due to selectivity and precision of its performance. Nevertheless some colour changes have been detected using Nd:YAG laser sources, especially on white and red coloured substrates. Colour changes on white marble and other white architectural materials have already been widely surveyed. This chapter focuses on the interaction of laser radiation with two kinds of red materials: red Verona limestone and terracotta. These materials have been chosen because of their large use in northern Italian architecture and in statuary. Red Verona limestone is not homogenous in hue, owing to the presence of calcareous nodules (lighter in colour) and clay veins (dark reddish colour).

  10. Micro-processing of polymers and biological materials using high repetition rate femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Ding, Li

    High repetition rate femtosecond laser micro-processing has been applied to ophthalmological hydrogel polymers and ocular tissues to create novel refractive and diffractive structures. Through the optimization of laser irradiation conditions and material properties, this technology has become feasible for future industrial applications and clinical practices. A femtosecond laser micro-processing workstation has been designed and developed. Different experimental parameters of the workstation such as laser pulse duration, focusing lens, and translational stages have been described and discussed. Diffractive gratings and three-dimensional waveguides have been fabricated and characterized in hydrogel polymers, and refractive index modifications as large as + 0.06 have been observed within the laser-irradiated region. Raman spectroscopic studies have shown that our femtosecond laser micro-processing induces significant thermal accumulation, resulting in a densification of the polymer network and increasing the localized refractive index of polymers within the laser irradiated region. Different kinds of dye chromophores have been doped in hydrogel polymers to enhance the two-photon absorption during femtosecond laser micro-processing. As the result, laser scanning speed can be greatly increased while the large refractive index modifications remain. Femtosecond laser wavelength and pulse energy as well as water and dye concentration of the hydrogels are optimized. Lightly fixed ocular tissues such as corneas and lenses have been micro-processed by focused femtosecond laser pulses, and refractive index modifications without any tissue-breakdown are observed within the stromal layer of the corneas and the cortex of the lenses. Living corneas are doped with Sodium Fluorescein to increase the two-photon absorption during the laser micro-processing, and laser scanning speed can be greatly increased while inducing large refractive index modifications. No evidence of cell death

  11. IR and green femtosecond laser machining of heat sensitive materials for medical devices at micrometer scale

    NASA Astrophysics Data System (ADS)

    Stolberg, Klaus; Friedel, Susanna; Kremser, Bert; Roehner, Markus

    2014-03-01

    In medical device manufacturing there is an increasing interest to enhance machining of biocompatible materials on a micrometer scale. Obviously there is a trend to generate smaller device structures like cavities, slits or total size of the device to address new applications. Another trend points to surface modification, which allows controlling selective growth of defined biological cell types on medical implants. In both cases it is interesting to establish machining methods with minimized thermal impact, because biocompatible materials often show degradation of mechanical properties under thermal treatment. Typical examples for this effect is embrittlement of stainless steel at the edge of a cutting slit, which is caused by oxidation and phase change. Also for Nitinol (NiTi alloy) which is used as another stent material reduction of shape-memory behavior is known if cutting temperature is too high. For newest biodegradable materials like Polylactic acid (PLA) based polymers, lowest thermal impact is required due to PLA softening point (65°C) and melting temperature (~170 °C ). Laser machining with ultra-short pulse lasers is a solution for this problem. In our work we demonstrate a clean laser cut of NiTi and PLA based polymers with a high repetition-rate 1030 nm, 400-800 fs laser source at a pulse energy of up to 50 μJ and laser repetition rate of up to 500 kHz.

  12. Measurement of the fluorescence of restorative dental materials using a 655-nm diode laser

    NASA Astrophysics Data System (ADS)

    Zanin, Fatima A. A.; Souza-Campos, Dilma H.; Zanin, Sissi; Brugnera, Aldo, Jr.; Pecora, Jesus D.; Pinheiro, Antonio L. B.; Harari, Sonia

    2001-04-01

    The aim of this study was to determine the level of fluorescence of seven restorative materials using 655 nm diode laser. The laser fluorescence system has ben used as an auxiliary method for the detection of carious lesions. This new diagnostic method increases information which are important for the choice of treatment by the Dentist. The characteristic of restorative materials and sealers interferes in the values obtained by the apparatus during the detection of secondary carious lesions. The optical properties of each biological tissue or material are related to the interaction with the laser beam. Aware of that, the fluorescence of healthy dentin and enamel is 0-15, the authors determined the fluorescence of seven restorative materials with 10 teeth in each group. The laser reading scale differed according to the materia, ranging from 1 to 22 with several materials, for example the sealer without inorganic filler and the glass ionomer, showing fluorescence values similar to carious enamel which interferes with the readings around the restorations resulting in a false positive. Knowledge of restoration material fluorescence can aid in the detection of secondary carious lesions around the restorations.

  13. Trans-scleral selective laser trabeculoplasty (SLT) without a gonioscopy lens (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Belkin, Michael; Geffen, Noa; Goldenfeld, Modi; Ofir, Shay; Belkin, Avner; Assia, Ehud

    2016-03-01

    Developing a one-second automatic glaucoma treatment using trans-scleral laser trabeculoplasty (LTP) without a gonioscopy lens Purpose: Developing an LTP device for delivering multiple simultaneous trans-scleral applications of low energy laser irradiation to the trabecular meshwork (TM) for reducing Intraocular Pressure (IOP). Methods: Concept proof: A randomized, masked, controlled one was performed on open angle glaucoma patients. The control group underwent conventional SLT (100 laser spots through a gonioscope for 360 degrees directly on the TM). The trial group underwent irradiation by the same laser at the same irradiation parameters on the sclera overlying the TM. Topical glaucoma therapy was not changed during the 12 months trial. Feasibility trial: Using optimized laser parameters, 60 discrete applications were administered on similar locations of patients' sclera. Results: Concept proof: Trans-scleral applications: (N=15), IOP decrease from 20.21 mmHg before treatment to 16.00 (27.1%) at one year. The corresponding numbers for the control group (n=15), were 21.14 mmHg and 14.30 (23.4%). There was no statistical difference between the two groups in IOP reduction. The complications rate was significantly higher in the control group. Trial 2: IOP was reduced from an of 25.3 mmHg to 19.3 (23.7%) in the 11 patients. Conclusions: Laser coherency, lost in tissue transmission, is not required for the therapeutic effect. The new method will possibly enable treatment of angle closure glaucoma as well as simultaneous applications of all laser spots to the sclera. When used conjointly with target acquisition, will make feasible an automatic glaucoma treatment in less than one second.

  14. A Theory of Interaction Mechanism between Laser Beam and Paper Material

    NASA Astrophysics Data System (ADS)

    Piili, Heidi

    Paper making and converting industry in Europe is suffering from transfer of basic manufacturing to fast-growing economies, such as China and Brazil. Pulp and paper production volume in Finland, Sweden and France was the same in 2011 as it was in 2000. Meanwhile China has tripled its volume and Brazil doubled. This is a situation where innovative solutions for papermaking and converting industry are needed. Laser can be solution for this, as it is fast, flexible, accurate and reliable. Before industrial application, characteristics of laser beam and paper material interaction has to be understood. When this fundamental knowledge is known, new innovations can be created. Fulfilling the lack of information on interaction phenomena can assist in the way of lasers for wider use of technology in paper making and converting industry. This study was executed by treating dried kraft pulp (grammage 67 g m-2) with different laser power levels, focal point settings and interaction time. Laser equipment was TRUMPF TLF HQ2700 CO2 laser (wavelength 10.6 μm). Interaction between laser beam and dried kraft pulp was detected with multi-monitoring system (MMS), which consisted of spectrometer, pyrometer and active illumination imaging system. There is two different dominating mechanisms in interaction between laser beam and paper material. Furthermore, it was noticed that there is different interaction phases within these two interaction mechanisms. These interaction phases appear as function of time and as function of peak intensity of laser beam. Limit peak intensity divides interaction mechanism from one-phase interaction into dual-phase interaction.

  15. Time-resolved study of femtosecond laser induced micro-modifications inside transparent brittle materials

    NASA Astrophysics Data System (ADS)

    Hendricks, F.; Matylitsky, V. V.; Domke, M.; Huber, Heinz P.

    2016-03-01

    Laser processing of optically transparent or semi-transparent, brittle materials is finding wide use in various manufacturing sectors. For example, in consumer electronic devices such as smartphones or tablets, cover glass needs to be cut precisely in various shapes. The unique advantage of material processing with femtosecond lasers is efficient, fast and localized energy deposition in nearly all types of solid materials. When an ultra-short laser pulse is focused inside glass, only the localized region in the neighborhood of the focal volume absorbs laser energy by nonlinear optical absorption. Therefore, the processing volume is strongly defined, while the rest of the target stays unaffected. Thus ultra-short pulse lasers allow cutting of the chemically strengthened glasses such as Corning Gorilla glass without cracking. Non-ablative cutting of transparent, brittle materials, using the newly developed femtosecond process ClearShapeTM from Spectra-Physics, is based on producing a micron-sized material modification track with well-defined geometry inside. The key point for development of the process is to understand the induced modification by a single femtosecond laser shot. In this paper, pump-probe microscopy techniques have been applied to study the defect formation inside of transparent materials, namely soda-lime glass samples, on a time scale between one nanosecond to several tens of microseconds. The observed effects include acoustic wave propagation as well as mechanical stress formation in the bulk of the glass. Besides better understanding of underlying physical mechanisms, our experimental observations have enabled us to find optimal process parameters for the glass cutting application and lead to better quality and speed for the ClearShapeTM process.

  16. Ultrafast dynamic ellipsometry and spectroscopies of laser shocked materials

    SciTech Connect

    Mcgrane, Shawn David; Bolme, Cindy B; Whitley, Von H; Moore, David S

    2010-01-01

    Ultrafast ellipsometry and transient absorption spectroscopies are used to measure material dynamics under extreme conditions of temperature, pressure, and volumetric compression induced by shock wave loading with a chirped, spectrally clipped shock drive pulse.

  17. Laser cleaning experiences on sculptures' materials: terracotta, plaster, wood, and wax

    NASA Astrophysics Data System (ADS)

    Pelosi, Claudia; Fodaro, D.; Sforzini, Livia; Lo Monaco, Angela

    2013-11-01

    The focus of this paper is to show the work experiences with laser cleaning on sculptures made of terracotta, plaster, wood and wax. These materials exhibit peculiar features that often prevent the use of traditional cleaning procedures to remove the surface dirt, soot or carbonaceous deposits and other materials coming from environment or ancient conservative interventions. To overcome the difficulties in the cleaning of the above mentioned materials, laser technology was tested. The laser irradiation and cleaning tests were carried out with a Q-switched Nd:YAG system under the following conditions: wavelength 1064 nm and 532 nm; energy 4-28 mJ; pulse duration 10 ns; spot diameter 2-8 mm; frequency 5 Hz. The irradiated surfaces were analyzed before and after the laser tests, with the aid of a video microscope and a reflectance spectrophotometer, in order to evaluate the morphology and colour changes of the surfaces. Before starting with the cleaning intervention, some diagnostic analysis was performed on the sculptures in order to obtain the identification of the original materials and of the surface deposits. Concerning this, Fourier Transform Infrared spectroscopy, X-ray fluorescence spectroscopy, and internal micro stratigraphic analysis were performed. This research demonstrated that the laser cleaning is an effective method to remove the surface deposits preserving the original patina of the sculptures and the opacity of the wax. The results gathered in this work encourage to continue the research in order to better understand the interactions between the laser beam and the surfaces and to find the most appropriate laser conditions to clean the sculptures.

  18. Direct laser immobilization of photosynthetic material on screen printed electrodes for amperometric biosensor

    SciTech Connect

    Boutopoulos, Christos; Zergioti, Ioanna; Touloupakis, Eleftherios; Pezzotti, Ittalo; Giardi, Maria Teresa

    2011-02-28

    This letter demonstrates the direct laser printing of photosynthetic material onto low cost nonfunctionalized screen printed electrodes for the fabrication of photosynthesis-based amperometric biosensors. The high kinetic energy of the transferred material induces direct immobilization of the thylakoids onto the electrodes without the use of linkers. This type of immobilization is able to establish efficient electrochemical contact between proteins and electrode, stabilizing the photosynthetic biomolecule and transporting electrons to the solid state device with high efficiency. The functionality of the laser printed biosensors was evaluated by the detection of a common herbicide such as Linuron.

  19. Root apex sealing with different filling materials photopolymerized with argon ion laser light

    NASA Astrophysics Data System (ADS)

    Lupato Conrado, Luis Augusto; Frois, Iris M.; Amaro Zangaro, Renato; Munin, Egberto

    2003-06-01

    The present study evaluates the seal quality in apex delta of single root human teeth filled with light-curing materials (Ultrablend Calcium-hydroxide, Vitremer glass ionomer and Flow-Fill Magic composite). 45 roots prepared by the endo PTC/Dakin technique were used. All prepared samples received photopolymerization with the blue 488 nm argon ion laser light. A 200 μm optical fiber introduced into the root canal delivered 100 mW of light power to the light-curing material. The fiber tip was positioned 5 mm away from the apex. Light was applied for 20 seconds. After curing, the samples received impermeabilization with ethyl-cyanoacrylate, leaving only the apex exposed, and then immersed in a methylene-blue dye solution for 24 hours. The samples were cut longitudinally and analyzed under a stereoscopic microscope for dye infiltration. It was found that those samples sealed with Ultrablend Calcium-hydroxide or the glass ionomer presented the best results, as compared to those samples sealed with the Flow-Fill Magic composite. No statistically significant difference was observed between the group treated with Ultrablend Calcium-hydroxide and the group treated with the glass ionomer, for a significance level of 0.05.

  20. Formation and properties of 3D metamaterial composites fabricated using nanometer scale laser lithography (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Prokes, Sharka M.; Perkins, Frank K.; Glembocki, Orest J.

    2015-08-01

    Metamaterials designed for the visible or near IR wavelengths require patterning on the nanometer scale. To achieve this, e-beam lithography is used, but it is extremely difficult and can only produce 2D structures. A new alternative technique to produce 2D and 3D structures involves laser fabrication using the Nanoscribe 3D laser lithography system. This is a direct laser writing technique which can form arbitrary 3D nanostructures on the nanometer scale and is based on multi-photon polymerization. We are creating 2D and 3D metamaterials via this technique, and subsequently conformally coating them using Atomic Layer Deposition of oxides and Ag. We will discuss the optical properties of these novel composite structures and their potential for dual resonant metamaterials.

  1. ISO WD 1856. Guideline for radiation exposure of nonmetallic materials. Present status

    NASA Astrophysics Data System (ADS)

    Briskman, B. A.

    In the framework of the International Organization for Standardization (ISO) activity we started development of international standard series for space environment simulation at on-ground tests of materials. The proposal was submitted to ISO Technical Committee 20 (Aircraft and Space Vehicles), Subcommittee 14 (Space Systems and Operations) and was approved as Working Draft 15856 at the Los-Angeles meeting (1997). A draft of the first international standard "Space Environment Simulation for Radiation Tests of Materials" (1st version) was presented at the 7th International Symposium on Materials in Space Environment (Briskman et al, 1997). The 2nd version of the standard was limited to nonmetallic materials and presented at the 20th Space Simulation Conference (Briskman and Borson, 1998). It covers the testing of nonmetallic materials embracing also polymer composite materials including metal components (metal matrix composites) to simulated space radiation. The standard does not cover semiconductor materials. The types of simulated radiation include charged particles (electrons and protons), solar ultraviolet radiation, and soft X-radiation of solar flares. Synergistic interactions of the radiation environment are covered only for these natural and some induced environmental effects. This standard outlines the recommended methodology and practices for the simulation of space radiation on materials. Simulation methods are used to reproduce the effects of the space radiation environment on materials that are located on surfaces of space vehicles and behind shielding. It was discovered that the problem of radiation environment simulation is very complex and the approaches of different specialists and countries to the problem are sometimes quite opposite. To the present moment we developed seven versions of the standard. The last version is a compromise between these approaches. It was approved at the last ISO TC20/SC14/WG4 meeting in Houston, October 2002. At a

  2. Experimental observations of soliton explosions in ultrafast fibre lasers (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Broderick, Neil; Runge, Antoine; Erkintalo, Miro

    2016-04-01

    A soliton explosion is a dramatic effect, whereby a pulse circulating in a mode-locked laser dissipates and then remarkably reforms within a few roundtrips. Our group recently reported the first observation of such explosions in an all-fibre laser. Here, we expand on our initial work, reporting a detailed numerical and experimental study of the dynamics and characteristics of soliton explosions. Our experiment is based on a passively mode-locked Yb-doped fiber laser, where explosions occur close to the boundary between stable and noise-like operation. To capture the events, we use the dispersive Fourier transformation to record, in real time, the pulse-to-pulse spectra emitted by the laser. We explore a variety of operating conditions by systematically adjusting the laser pump power and its cavity length. We also use a realistic model based on a set of generalized nonlinear Schrodinger equations to simulate the explosion dynamics. We find that the explosion dynamics can be influenced by adjusting the operating conditions. As a general trend, the frequency of the events increases as the conditions move closer to the boundary of unstable operation. In fact, when sufficiently close to the boundary, the "explosions" can even become more frequent than ordinary pulses. Moreover, our simulations reveal that complex features in the spectral and temporal profiles of the explosion events can be explained in terms of a multi-pulsing instability. Finally we have examined how the statistics of the events depend on the laser geometry and also whether such explosions indicate the existence of a "strange attractor".

  3. High-speed high-sensitivity infrared spectroscopy using mid-infrared swept lasers (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Childs, David T. D.; Groom, Kristian M.; Hogg, Richard A.; Revin, Dmitry G.; Cockburn, John W.; Rehman, Ihtesham U.; Matcher, Stephen J.

    2016-03-01

    Infrared spectroscopy is a highly attractive read-out technology for compositional analysis of biomedical specimens because of its unique combination of high molecular sensitivity without the need for exogenous labels. Traditional techniques such as FTIR and Raman have suffered from comparatively low speed and sensitivity however recent innovations are challenging this situation. Direct mid-IR spectroscopy is being speeded up by innovations such as MEMS-based FTIR instruments with very high mirror speeds and supercontinuum sources producing very high sample irradiation levels. Here we explore another possible method - external cavity quantum cascade lasers (EC-QCL's) with high cavity tuning speeds (mid-IR swept lasers). Swept lasers have been heavily developed in the near-infrared where they are used for non-destructive low-coherence imaging (OCT). We adapt these concepts in two ways. Firstly by combining mid-IR quantum cascade gain chips with external cavity designs adapted from OCT we achieve spectral acquisition rates approaching 1 kHz and demonstrate potential to reach 100 kHz. Secondly we show that mid-IR swept lasers share a fundamental sensitivity advantage with near-IR OCT swept lasers. This makes them potentially able to achieve the same spectral SNR as an FTIR instrument in a time x N shorter (N being the number of spectral points) under otherwise matched conditions. This effect is demonstrated using measurements of a PDMS sample. The combination of potentially very high spectral acquisition rates, fundamental SNR advantage and the use of low-cost detector systems could make mid-IR swept lasers a powerful technology for high-throughput biomedical spectroscopy.

  4. 2000W high beam quality diode laser for direct materials processing

    NASA Astrophysics Data System (ADS)

    Qin, Wen-bin; Liu, You-qiang; Cao, Yin-hua; Gao, Jing; Pan, Fei; Wang, Zhi-yong

    2011-11-01

    This article describes high beam quality and kilowatt-class diode laser system for direct materials processing, using optical design software ZEMAX® to simulate the diode laser optical path, including the beam shaping, collimation, coupling, focus, etc.. In the experiment, the diode laser stack of 808nm and the diode laser stack of 915nm were used for the wavelength coupling, which were built vertical stacks up to 16 bars. The threshold current of the stack is 6.4A, the operating current is 85A and the output power is 1280W. Through experiments, after collimating the diode laser beam with micro-lenses, the fast axis BPP of the stack is less than 60mm.mrad, and the slow-axis BPP of the stack is less than 75mm.mrad. After shaping the laser beam and improving the beam quality, the fast axis BPP of the stack is still 60mm.mrad, and the slow-axis BPP of the stack is less than 19mm.mrad. After wavelength coupling and focusing, ultimately the power of 2150W was obtained, focal spot size of 1.5mm * 1.2mm with focal length 300mm. The laser power density is 1.2×105W/cm2, and that can be used for metal remelting, alloying, cladding and welding. The total optical coupling conversion efficiency is 84%, and the total electrical - optical conversion efficiency is 50%.

  5. Identification of carbohydrates by matrix-free material-enhanced laser desorption/ionisation mass spectrometry.

    PubMed

    Hashir, Muhammad Ahsan; Stecher, Guenther; Bakry, Rania; Kasemsook, Saowapak; Blassnig, Bernhard; Feuerstein, Isabel; Abel, Gudrun; Popp, Michael; Bobleter, Ortwin; Bonn, Guenther K

    2007-01-01

    Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) is a sensitive mass spectrometric technique which utilises acidic materials as matrices for laser energy absorption, desorption and ionisation of analytes. These matrix materials produce background signals particularly in the low-mass range and make the detection and identification of small molecules difficult and nearly impossible. To overcome this problem this paper introduces matrix-free material-enhanced laser desorption/ionisation mass spectrometry (mf-MELDI-MS) for the screening and analysis of small molecules such as carbohydrates. For this purpose, 4,4'-azo-dianiline was immobilised on silica gel enabling the absorption of laser energy sufficient for successful desorption and ionisation of low molecular weight compounds. The particle and pore sizes, the solvent system for suspension and the sample preparation procedures have been optimised. The newly synthesised MELDI material delivered excellent spectra with regard to signal-to-noise ratio and detection sensitivity. Finally, wheat straw degradation products and Salix alba L. plant extracts were analysed proving the high performance and excellent behaviour of the introduced material.

  6. Development of Advanced Coatings for Laser Modifications Through Process and Materials Simulation

    NASA Astrophysics Data System (ADS)

    Martukanitz, R. P.; Babu, S. S.

    2004-06-01

    A simulation-based system is currently being constructed to aid in the development of advanced coating systems for laser cladding and surface alloying. The system employs loosely coupled material and process models that allow rapid determination of material compatibility over a wide range of processing conditions. The primary emphasis is on the development and identification of composite coatings for improved wear and corrosion resistance. The material model utilizes computational thermodynamics and kinetic analysis to establish phase stability and extent of diffusional reactions that may result from the thermal response of the material during virtual processing. The process model is used to develop accurate thermal histories associated with the laser surface modification process and provides critical input for the non-isothermal materials simulations. These techniques were utilized to design a laser surface modification experiment that utilized the addition of stainless steel alloy 431 and TiC produced using argon and argon and nitrogen shielding. The deposits representing alloy 431 and TiC powder produced in argon resulted in microstructures retaining some TiC particles and an increase in hardness when compared to deposits produced using only the 431 powder. Laser deposits representing alloy 431 and TiC powder produced with a mixture of argon and nitrogen shielding gas resulted in microstructures retaining some TiC particles, as well as fine precipitates of Ti(CN) formed during cooling and a further increase in hardness of the deposit.

  7. Multi-material laser densification (MMLD) of dental restorations: Process optimization and properties evaluation

    NASA Astrophysics Data System (ADS)

    Li, Xiaoxuan

    This Ph.D. thesis proposes to investigate the feasibility of laser-assisted dental restoration and to develop a fundamental understanding of the interaction between laser beam and dental materials. Traditional dental restorations are produced by the porcelain-fused-to-metal (PFM) process, in which a dental restoration is cast from a metallic alloy and then coated with dental porcelains by multiple furnace-firing processes. PFM method is labor-intensive and hence very expensive. In order to fabricate dental restoration units faster and more cost-effectively, the Solid Freeform Fabrication (SFF) technique has been employed in this study. In particular, a Multi-Material Laser Densification (MMLD) process has been investigated for its potential to fabricate artificial teeth automatically from 3-D computer dental tooth files. Based on the principle of SFF, the MMLD process utilizes a micro-extruder system to deliver commercial dental alloy and porcelain slurry in a computer-controlled pattern line by line and layer by layer. Instead of firing the artificial tooth/teeth in a furnace, the extruded dental materials are laser scanned to convert the loose powder to a fully dense body. Different laser densification parameters including the densification temperature, laser output power, laser beam size, line dimension, ratio of the beam size to line width, beam scanning rate, processing atmosphere and pressure, dental powder state (powder bed or slurry), powder particle size, etc. have been used to evaluate their effects on the microstructures and properties of the laser densified dental body, and hence to optimize MMLD conditions. Furthermore, laser-scanning induced phase transformations in dental porcelains have been studied because the transformations have great impact on coefficient of thermal expansion (CTE) of dental porcelains, which should match that of dental alloy substrate. Since a single dental material line delivered by the MMLD system functions as a "construction

  8. High power laser and materials investigation. Final report, 31 July 1978-28 October 1979

    SciTech Connect

    Chicklis, E.P.; Folweiler, R.C.; Pollak, T.M.; Baer, J.

    1980-06-01

    This is a combined study of resonant pumped solid state lasers as fusion drivers, and the development of crystalline optical materials suitable for propagation of the high peak powers associated with laser fusion research. During this period of study the concept of rare gas halide lasers was first demonstrated by the lasing of Tm:YLF at 453 nm pumped by the 353 nm energy of XeF. Excited stata densities of 5 x 10/sup 18/ cm/sup -3/ have been attained and spectroscopic measurements show that up to 60% of the pump energy can be converted into useful stored energy. Alternative lasers and pumping schemes are also discussed. In all cases the potential RGH/SS systems are evaluated in respect to internal efficiency and heat loading.

  9. Automatic laser-based material identification and marking: a new approach

    NASA Astrophysics Data System (ADS)

    Quay, Ruediger; Sattmann, R.; Noll, Reinhard

    1997-08-01

    Laser-Induced Breakdown Spectroscopy (LIBS) is a remote, online, in situ technique used for the quantitative analysis of elemental constituents in matrices such as steels, non ferrous metals, polymers and soils. A typical industrial application already established is the sorting of non ferrous metals for the purpose of recycling. A new device, the Laser Identification and Marking System introduced here, uses a combination of material identification by means of LIBS and instantly marking the workpiece using the same Nd:YAG laser. This method was developed since the application required a strongly decreased probability of mixing up of different steel qualities in comparison to conventional methods. At the same time a decisive disadvantage of LIBS, the insufficient detection limits for several elements, can be lowered by using repetitive bursts of multiple laser pulses.

  10. Molecular Engineering of Host Materials for Blue Phosphorescent OLEDs: Past, Present and Future

    SciTech Connect

    Cosimbescu, Lelia; Koech, Phillip K.; Polikarpov, Evgueni; Swensen, James S.; Von Ruden, Amber L.; Rainbolt, James E.; Padmaperuma, Asanga B.

    2010-04-15

    We report molecular design considerations for blue phosphorescent host materials, as well as propose design rules necessary to build ambipolar hosts and thus reach charge balance in a device. Our beginning developments are presented followed by the evolution of the original design to our state-of-the-art, with the help of computational modeling.

  11. The Use of Folklore and Other Materials in the Motivation or Presentation of a Lesson.

    ERIC Educational Resources Information Center

    Adorno, Elvira

    1951-01-01

    Suggestions on how to improve apperception, motivation, and the presentation of materials in the teaching of Italian tenses, vocabulary, and famous names focus on the use of literary devices largely derived from folklore. For teaching tenses, the author illustrates the use of riddles, "passerotti", "filastrocche", songs, tongue-twisters, rebuses,…

  12. The effect of target materials on colliding laser-produced plasmas

    NASA Astrophysics Data System (ADS)

    Li, Xingwen; Yang, Zefeng; Wu, Jian; Han, Jiaxun; Wei, Wenfu; Jia, Shenli; Qiu, Aici

    2016-04-01

    In laser ablation, nanosecond to femtosecond lasers with a wide range of laser power densities are used. During ablation, the result of collisions between two plasmas is of interest to many researchers in inertial confinement fusion and nuclear astrophysics. In this paper, the collisions of two seed plasmas ablated from planar target surfaces of different target materials (Al, Cu, and W) were studied with temporal-spatially resolved imaging and spectroscopy. The initial relative velocities and densities of the seed plasmas were measured, and then the collisional parameters were calculated to evaluate the degree of the collisions. In addition, spatially resolved spectra were analyzed to study the influences of materials on the temporal-spatial distribution of atom or ions. The results indicated that under the same laser intensity, the high atomic number (Z) material had a small value of collisionality parameter, mostly because of its heavy ion mass. Higher laser intensity would increase the initial relative velocity of seed plasmas, resulting in a lower collision frequency. In addition, the distribution of the ions from seed plasmas was influenced by the stagnation layer plasmas.

  13. Laser processing inside transparent materials: dependence on pulse length and wavelength

    NASA Astrophysics Data System (ADS)

    Loeschner, U.; Schille, J.; Ebert, R.; Exner, H.

    2011-03-01

    In this paper processing of transparent materials by laser radiation from various sources with short (nanoseconds) and ultrashort (femtoseconds) pulse lengths at different wavelengths is discussed. The investigations were carried out with a short pulse Nd:YVO4 laser (1064 nm, 532 nm) and a high repetition rate femtosecond fiber laser (1030 nm). In our experiments the laser beam was guided across the probe either through the motion of a coordinate table or through a laser scanner with an f-theta-objective. In our study we investigated in detail the influence of important process parameters like wavelength, pulse width, and irradiation regime upon micro defect generation inside bulk glass (BK glass, fused silica) and polymers (polymethylmethacrylate, polycarbonate, cyclo-olefin-copolymers). By applying an irradiation regime with optimal process parameters these locally confined material defects can be aligned as to yield cut surfaces for the excision of 3d parts that consist of transparent material with bulk properties. Especially for the production of irregularly shaped 3d parts a CAD-CAM software tool was developed that automatically converts geometry data into a processing program.

  14. Eye-safe infrared laser-induced breakdown spectroscopy (LIBS) emissions from energetic materials

    NASA Astrophysics Data System (ADS)

    Brown, Ei E.; Hömmerich, Uwe; Yang, Clayton C.; Jin, Feng; Trivedi, Sudhir B.; Samuels, Alan C.

    2016-05-01

    Laser-induced breakdown spectroscopy is a powerful diagnostic tool for detection of trace elements by monitoring the atomic and ionic emission from laser-induced plasmas. Besides elemental emissions from conventional UV-Vis LIBS, molecular LIBS emission signatures of the target compounds were observed in the long-wave infrared (LWIR) region in recent studies. Most current LIBS studies employ the fundamental Nd:YAG laser output at 1.064 μm, which has extremely low eye-damage threshold. In this work, comparative LWIR-LIBS emissions studies using traditional 1.064 μm pumping and eye-safe laser wavelength at 1.574 μm were performed on several energetic materials for applications in chemical, biological, and explosive (CBE) sensing. A Q-switched Nd: YAG laser operating at 1.064 μm and the 1.574 μm output of a pulsed Nd:YAG pumped Optical Parametric Oscillator were employed as the excitation sources. The investigated energetic materials were studied for the appearance of LWIR-LIBS emissions (4-12 μm) that are directly indicative of oxygenated breakdown products as well as partially dissociated and recombination molecular species. The observed molecular IR LIBS emission bands showed strong correlation with FTIR absorption spectra of the studied materials for 1.064 μm and 1.574 μm pump wavelengths.

  15. Formation of nanoporous structures in metallic materials by pulse-periodic laser treatment

    NASA Astrophysics Data System (ADS)

    Murzin, Serguei P.

    2015-09-01

    A method of the formation of nanoporous structures in metallic materials by pulse-periodic laser treatment was developed. In this study, the multicomponent aluminum-iron brass was considered and the nanoporous structure across the entire cross section of the material with a thickness of 50 μm was formed. The method was implemented using a CO2 laser processing unit. The pulse-periodic laser treatment of the Cu-Zn-Al-Fe alloy with pulse frequency of 5 Hz has led to the formation of nanosized cavities due to accumulation of internal stresses during cyclic heating and cooling at high speeds. It was determined that the pores of a channel type with average widths of 80-100 nm are formed in the central region of the heat-affected zone during laser action with thermocycling. When implementing the chosen conditions of the pulse-periodic laser processing, the localness in depth and area of the physical processes occurring in the heat-affected zone is ensured, while maintaining the original properties of the material and the absence of significant deformations in the rest of the volume. This patented process is perspective for the production not only catalysts for chemical reactions, but for ultrafiltration and microfiltration membranes as well.

  16. The application of Maxwell’s equations for numerical simulation of processes during laser treatment of materials

    NASA Astrophysics Data System (ADS)

    Kovalev, О B.; Galjov, R. V.

    2015-08-01

    A number of problems on the laser radiation propagation and absorption are stated on the Maxwell’s equation base for the simulation of laser treatment of materials, namely cutting, welding, drilling of metals, selective laser melting and sintering of powders. The algorithm of numerical solution of the Maxwell’s equations by the finite difference time domain method is employed with parallelizing elements; the peculiarities of setting of some boundary conditions for the problems of laser interaction for isotropic media are analyzed.

  17. Design of high-brightness TEM00-mode solar-pumped laser for renewable material processing

    NASA Astrophysics Data System (ADS)

    Liang, D.; Almeida, J.

    2014-08-01

    The conversion of sunlight into laser light by direct solar pumping is of ever-increasing importance because broadband, temporally constant, sunlight is converted into laser light, which can be a source of narrowband, collimated, rapidly pulsed, radiation with the possibility of obtaining extremely high brightness and intensity. Nonlinear processes, such as harmonic generation, might be used to obtain broad wavelength coverage, including the ultraviolet wavelengths, where the solar flux is very weak. The direct excitation of large lasers by sunlight offers the prospect of a drastic reduction in the cost of coherent optical radiation for high average power materials processing. This renewable laser has a large potential for many applications such as high-temperature materials processing, renewable magnesium-hydrogen energy cycle and so on. We propose here a scalable TEM00 mode solar laser pumping scheme, which is composed of four firststage 1.13 m diameter Fresnel lenses with its respective folding mirrors mounted on a two-axis automatic solar tracker. Concentrated solar power at the four focal spots of these Fresnel lenses are focused individually along a common 3.5 mm diameter, 70 mm length Nd:YAG rod via four pairs of second-stage fused-silica spherical lenses and third-stage 2D-CPCs (Compound Parabolic Concentrator), sitting just above the laser rod which is also double-pass pumped by four V-shaped pumping cavities. Distilled water cools both the rod and the concentrators. 15.4 W TEM00 solar laser power is numerically calculated, corresponding to 6.7 times enhancement in laser beam brightness.

  18. Momentum transfer Monte Carlo model for the simulation of laser speckle contrast imaging (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Regan, Caitlin; Hayakawa, Carole K.; Choi, Bernard

    2016-03-01

    Laser speckle imaging (LSI) enables measurement of relative blood flow in microvasculature and perfusion in tissues. To determine the impact of tissue optical properties and perfusion dynamics on speckle contrast, we developed a computational simulation of laser speckle contrast imaging. We used a discrete absorption-weighted Monte Carlo simulation to model the transport of light in tissue. We simulated optical excitation of a uniform flat light source and tracked the momentum transfer of photons as they propagated through a simulated tissue geometry. With knowledge of the probability distribution of momentum transfer occurring in various layers of the tissue, we calculated the expected laser speckle contrast arising with coherent excitation using both reflectance and transmission geometries. We simulated light transport in a single homogeneous tissue while independently varying either absorption (.001-100mm^-1), reduced scattering (.1-10mm^-1), or anisotropy (0.05-0.99) over a range of values relevant to blood and commonly imaged tissues. We observed that contrast decreased by 49% with an increase in optical scattering, and observed a 130% increase with absorption (exposure time = 1ms). We also explored how speckle contrast was affected by the depth (0-1mm) and flow speed (0-10mm/s) of a dynamic vascular inclusion. This model of speckle contrast is important to increase our understanding of how parameters such as perfusion dynamics, vessel depth, and tissue optical properties affect laser speckle imaging.

  19. Development of Solid State Laser Materials for Application in Lasers for Atmospheric Ozone and Water Vapor Sensing

    NASA Technical Reports Server (NTRS)

    Noginov, Makhail A.; Loutts, G. B.

    2002-01-01

    We have grown neodymium doped mixed apatite crystals, (Sr(x)Ba(l-x)5(PO4)3F, Sr5(P(1-x)V(x)O4)3F, and Ba5(P(1-x)V(x)O4)3F, and spectroscopically studied them as potential gain media for a laser source for atmospheric water sensing operating at 944.11 nm0. We conclude that an appropriate apatite host material for a 944.11 nm laser should be a mixture of Sr5(PO4)3F with a small fraction of Ba5(PO4)3F. The precise wavelength tuning around 944.11 nm can be accomplished by varying the host composition, temperature, and threshold population inversion. In apatite crystals of mixed composition, the Amplified Spontaneous Emission (ASE) loss at 1.06 microns is predicted to be significantly smaller than that in the end members.

  20. Development of Advanced Wear and Corrosion Resistant Systems Through Laser Surface Alloying and Materials Simulations

    SciTech Connect

    R. P. Martukanitz and S. Babu

    2007-05-03

    Laser surfacing in the form of cladding, alloying, and modifications are gaining widespread use because of its ability to provide high deposition rates, low thermal distortion, and refined microstructure due to high solidification rates. Because of these advantages, laser surface alloying is considered a prime candidate for producing ultra-hard coatings through the establishment or in situ formation of composite structures. Therefore, a program was conducted by the Applied Research Laboratory, Pennsylvania State University and Oak Ridge National Laboratory to develop the scientific and engineering basis for performing laser-based surface modifications involving the addition of hard particles, such as carbides, borides, and nitrides, within a metallic matrix for improved wear, fatigue, creep, and corrosion resistance. This has involved the development of advanced laser processing and simulation techniques, along with the refinement and application of these techniques for predicting and selecting materials and processing parameters for the creation of new surfaces having improved properties over current coating technologies. This program has also resulted in the formulation of process and material simulation tools capable of examining the potential for the formation and retention of composite coatings and deposits produced using laser processing techniques, as well as positive laboratory demonstrations in producing these coatings. In conjunction with the process simulation techniques, the application of computational thermodynamic and kinetic models to design laser surface alloying materials was demonstrated and resulted in a vast improvement in the formulation of materials used for producing composite coatings. The methodology was used to identify materials and to selectively modify microstructures for increasing hardness of deposits produced by the laser surface alloying process. Computational thermodynamic calculations indicated that it was possible to induce the

  1. Two-beam Laser Brazing of Thin Sheet Steel for Automotive Industry Using Cu-base Filler Material

    NASA Astrophysics Data System (ADS)

    Mittelstädt, C.; Seefeld, T.; Reitemeyer, D.; Vollertsen, F.

    This work shows the potential of two-beam laser brazing for joining both Zn-coated steel and 22MnB5. Brazing of Zn-coated steel sheets using Cu-Si filler wire is already state of the art in car manufacturing. New press-hardened steels like 22MnB5 are more and more used in automotive industry, offering high potential to save costs and improve structural properties (reduced weight / higher stiffness). However, for joining of these ultra-high strength steels investigations are mandatory. In this paper, a novel approach using a two-beam laser brazing process and Cu-base filler material is presented. The use of Cu-base filler material leads to a reduced heat input, compared to currently applied welding processes, which may result in benefits concerning distortion, post processing and tensile strength of the joint. Reliable processing at desired high speeds is attained by means of laser-preheating. High feed rates prevent significant diffusion of copper into the base material.

  2. Initial Atomic Motion Immediately Following Femtosecond-Laser Excitation in Phase-Change Materials

    NASA Astrophysics Data System (ADS)

    Matsubara, E.; Okada, S.; Ichitsubo, T.; Kawaguchi, T.; Hirata, A.; Guan, P. F.; Tokuda, K.; Tanimura, K.; Matsunaga, T.; Chen, M. W.; Yamada, N.

    2016-09-01

    Despite the fact that phase-change materials are widely used for data storage, no consensus exists on the unique mechanism of their ultrafast phase change and its accompanied large and rapid optical change. By using the pump-probe observation method combining a femtosecond optical laser and an x-ray free-electron laser, we substantiate experimentally that, in both GeTe and Ge2 Sb2 Te5 crystals, rattling motion of mainly Ge atoms takes place with keeping the off-center position just after femtosecond-optical-laser irradiation, which eventually leads to a higher symmetry or disordered state. This very initial rattling motion in the undistorted lattice can be related to instantaneous optical change due to the loss of resonant bonding that characterizes GeTe-based phase change materials. Based on the amorphous structure derived by first-principles molecular dynamics simulation, we infer a plausible ultrafast amorphization mechanism via nonmelting.

  3. Laser supported detonation wave source of atomic oxygen for aerospace material testing

    NASA Technical Reports Server (NTRS)

    Krech, Robert H.; Caledonia, George E.

    1990-01-01

    A pulsed high-flux source of nearly monoenergetic atomic oxygen was developed to perform accelerated erosion testing of spacecraft materials in a simulated low-earth orbit (LEO) environment. Molecular oxygen is introduced into an evacuated conical expansion nozzle at several atmospheres pressure through a pulsed molecular beam valve. A laser-induced breakdown is generated in the nozzle throat by a pulsed CO2 TEA laser. The resulting plasma is heated by the ensuing laser-supported detonation wave, and then it rapidly expands and cools. An atomic oxygen beam is generated with fluxes above 10 to the 18th atoms per pulse at 8 + or - 1.6 km/s with an ion content below 1 percent for LEO testing. Materials testing yielded the same surface oxygen enrichment in polyethylene samples as observed on the STS mission, and scanning electron micrographs of the irradiated polymer surfaces showed an erosion morphology similar to that obtained on low earth orbit.

  4. Systems and Methods of Laser Texturing of Material Surfaces and Their Applications

    NASA Technical Reports Server (NTRS)

    Gupta, Mool C. (Inventor); Nayak, Barada K. (Inventor)

    2014-01-01

    The surface of a material is textured and by exposing the surface to pulses from an ultrafast laser. The laser treatment causes pillars to form on the treated surface. These pillars provide for greater light absorption. Texturing and crystallization can be carried out as a single step process. The crystallization of the material provides for higher electric conductivity and changes in optical and electronic properties of the material. The method may be performed in vacuum or a gaseous environment. The gaseous environment may aid in texturing and/or modifying physical and chemical properties of the surfaces. This method may be used on various material surfaces, such as semiconductors, metals and their alloys, ceramics, polymers, glasses, composites, as well as crystalline, nanocrystalline, polycrystalline, microcrystalline, and amorphous phases.

  5. Heat generation caused by ablation of dental restorative materials with an ultra short pulse laser (USPL) system

    NASA Astrophysics Data System (ADS)

    Braun, Andreas; Wehry, Richard; Brede, Olivier; Frentzen, Matthias; Schelle, Florian

    2011-03-01

    The aim of this study was to assess heat generation in dental restoration materials following laser ablation using an Ultra Short Pulse Laser (USPL) system. Specimens of phosphate cement (PC), ceramic (CE) and composite (C) were used. Ablation was performed with an Nd:YVO4 laser at 1064 nm and a pulse length of 8 ps. Heat generation during laser ablation depended on the thickness of the restoration material. A time delay for temperature increase was observed in the PC and C group. Employing the USPL system for removal of restorative materials, heat generation has to be considered.

  6. Improved Characterization of Transmitted Wavefront Error on CADB Epoxy-Free Bonded Solid State Laser Materials

    SciTech Connect

    Bayramian, A

    2010-12-09

    Current state-of-the-art and next generation laser systems - such as those used in the NIF and LIFE experiments at LLNL - depend on ever larger optical elements. The need for wide aperture optics that are tolerant of high power has placed many demands on material growers for such diverse materials as crystalline sapphire, quartz, and laser host materials. For such materials, it is either prohibitively expensive or even physically impossible to fabricate monolithic pieces with the required size. In these cases, it is preferable to optically bond two or more elements together with a technique such as Chemically Activated Direct Bonding (CADB{copyright}). CADB is an epoxy-free bonding method that produces bulk-strength bonded samples with negligible optical loss and excellent environmental robustness. The authors have demonstrated CADB for a variety of different laser glasses and crystals. For this project, they will bond quartz samples together to determine the suitability of the resulting assemblies for large aperture high power laser optics. The assemblies will be evaluated in terms of their transmitted wavefront error, and other optical properties.

  7. Electronic and structural response of materials to fast intense laser pulses, including light-induced superconductivity

    NASA Astrophysics Data System (ADS)

    Allen, Roland E.

    2016-06-01

    This is a very brief discussion of some experimental and theoretical studies of materials responding to fast intense laser pulses, with emphasis on those cases where the electronic response and structural response are both potentially important (and ordinarily coupled). Examples are nonthermal insulator-to-metal transitions and light-induced superconductivity in cuprates, fullerenes, and an organic Mott insulator.

  8. Nanoalloy Printed and Pulse-Laser Sintered Flexible Sensor Devices with Enhanced Stability and Materials Compatibility.

    PubMed

    Zhao, Wei; Rovere, Thomas; Weerawarne, Darshana; Osterhoudt, Gavin; Kang, Ning; Joseph, Pharrah; Luo, Jin; Shim, Bonggu; Poliks, Mark; Zhong, Chuan-Jian

    2015-06-23

    While conformal and wearable devices have become one of the most desired formats for printable electronics, it is challenging to establish a scalable process that produces stable conductive patterns but also uses substrates compatible with widely available wearable materials. Here, we describe findings of an investigation of a nanoalloy ink printed and pulsed-laser sintered conductive patterns as flexible functional devices with enhanced stability and materials compatibility. While nanoparticle inks are desired for printable electronics, almost all existing nanoparticle inks are based on single-metal component, which, as an electronic element, is limited by its inherent stabilities of the metal such as propensity of metal oxidation and mobility of metal ions, especially in sintering processes. The work here has demonstrated the first example in exploiting plasmonic coupling of nanoalloys and pulsed-laser energy with controllable thermal penetration. The experimental and theoretical results have revealed clear correlation between the pulsed laser parameters and the nanoalloy structural characteristics. The superior performance of the resulting flexible sensor device, upon imparting nanostructured sensing materials, for detecting volatile organic compounds has significant implications to developing stable and wearable sensors for monitoring environmental pollutants and breath biomarkers. This simple "nanoalloy printing-laser sintering-nanostructure printing" process is entirely general to many different sensor devices and nanostructured sensing materials, enabling the ability to easily construct sophisticated sensor array.

  9. Nanoalloy Printed and Pulse-Laser Sintered Flexible Sensor Devices with Enhanced Stability and Materials Compatibility

    SciTech Connect

    Zhao, Wei; Rovore, Thomas; Weerawarne, Darshana; Osterhoudt, Gavin; Kang, Ning; Joseph, Pharrah; Luo, Jin; Shim, Bonggu; Poliks, Mark; Zhong, Chuan-Jian

    2015-06-02

    While conformal and wearable devices have become one of the most desired formats for printable electronics, it is challenging to establish a scalable process that produces stable conductive patterns but also uses substrates compatible with widely available wearable materials. Here, we describe findings of an investigation of a nanoalloy ink printed and pulsed laser sintered conductive patterns as flexible functional devices with enhanced stability and materials compatibility. While nanoparticle inks are desired for printable electronics, almost all existing nanoparticle inks are based on single-metal component, which, as an electronic element, is limited by its inherent stabilities of the metal such as propensity of metal oxidation and mobility of metal ions, especially in sintering processes. The work here has demonstrated the first example in exploiting plasmonic coupling of nanoalloys and pulsed-laser energy with controllable thermal penetration. The experimental and theoretical results have revealed clear correlation between the pulsed laser parameters and the nanoalloy structural characteristics. The superior performance of the resulting flexible sensor device, upon imparting nanostructured sensing materials, for detecting volatile organic compounds has significant implications to developing stable and wearable sensors for monitoring environmental pollutants and breath biomarkers. This simple “nanoalloy printing 'laser sintering' nanostructure printing” process is entirely general to many different sensor devices and nanostructured sensing materials, enabling the ability to easily construct sophisticated sensor array.

  10. New Mid-IR Lasers Based on Rare-Earth-Doped Sulfide and Chloride Materials

    SciTech Connect

    Nostrand, M

    2000-09-01

    Applications in remote-sensing and military countermeasures have driven a need for compact, solid-state mid-IR lasers. Due to multi-phonon quenching, non-traditional hosts are needed to extend current solid-state, room-temperature lasing capabilities beyond {approx} 4 {micro}m. Traditional oxide and fluoride hosts have effective phonon energies in the neighborhood of 1000 cm{sup -1} and 500 cm{sup -1}, respectively. These phonons can effectively quench radiation above 2 and 4 {micro}m, respectively. Materials with lower effective phonon energies such as sulfides and chlorides are the logical candidates for mid-IR (4-10 {micro}m) operation. In this report, laser action is demonstrated in two such hosts, CaGa{sub 2}S{sub 4} and KPb{sub 2}Cl{sub 5}. The CaGa{sub 2}S{sub 4}:Dy{sup 3+} laser operating at 4.3 {micro}m represents the first sulfide laser operating beyond 2 {micro}m. The KPb{sub 2}Cl{sub 5}:Dy{sup 3+} laser operating at 2.4 {micro}m represents the first operation of a chloride-host laser in ambient conditions. Laser action is also reported for CaGa{sub 2}S{sub 4}:Dy{sup 3+} at 2.4 {micro}m, CaGa{sub 2}S{sub 4}:Dy{sup 3+} at 1.4 {micro}m, and KPb{sub 2}Cl{sub 5}:Nd{sup 3+} at 1.06 {micro}m. Both host materials have been fully characterized, including lifetimes, absorption and emission cross sections, radiative branching ratios, and radiative quantum efficiencies. Radiative branching ratios and radiative quantum efficiencies have been determined both by the Judd-Ofelt method (which is based on absorption measurements), and by a novel method described herein which is based on emission measurements. Modeling has been performed to predict laser performance, and a new method to determine emission cross section from slope efficiency and threshold data is developed. With the introduction and laser demonstration of rare-earth-doped CaGa{sub 2}S{sub 4} and KPb{sub 2}Cl{sub 5}, direct generation of mid-IR laser radiation in a solid-state host has been demonstrated. In

  11. High power lasers: Sources, laser-material interactions, high excitations, and fast dynamics in laser processing and industrial applications; Proceedings of the Meeting, The Hague, Netherlands, Mar. 31-Apr. 3, 1987

    NASA Technical Reports Server (NTRS)

    Kreutz, E. W. (Editor); Quenzer, Alain (Editor); Schuoecker, Dieter (Editor)

    1987-01-01

    The design and operation of high-power lasers for industrial applications are discussed in reviews and reports. Topics addressed include the status of optical technology in the Netherlands, laser design, the deposition of optical energy, laser diagnostics, nonmetal processing, and energy coupling and plasma formation. Consideration is given to laser-induced damage to materials, fluid and gas flow dynamics, metal processing, and manufacturing. Graphs, diagrams, micrographs, and photographs are provided.

  12. Fabrication of coatings and bulk products made of a nickel-based material by additive technology laser metal deposition

    NASA Astrophysics Data System (ADS)

    Gorunov, A. I.

    2016-01-01

    It is shown that products made of a nickel-based material can be formed by direct additive laser deposition. Ring samples with good antifriction properties are formed. The material after direct laser deposition is characterized by a heterogeneous structure: coarse inclusions with a high hardness are distributed in a softer matrix. Final laser treatment leads to the formation of a homogeneous microstructure and the refinement of second phases.

  13. Lateral Temperature-Gradient Method for High-Throughput Characterization of Material Processing by Millisecond Laser Annealing.

    PubMed

    Bell, Robert T; Jacobs, Alan G; Sorg, Victoria C; Jung, Byungki; Hill, Megan O; Treml, Benjamin E; Thompson, Michael O

    2016-09-12

    A high-throughput method for characterizing the temperature dependence of material properties following microsecond to millisecond thermal annealing, exploiting the temperature gradients created by a lateral gradient laser spike anneal (lgLSA), is presented. Laser scans generate spatial thermal gradients of up to 5 °C/μm with peak temperatures ranging from ambient to in excess of 1400 °C, limited only by laser power and materials thermal limits. Discrete spatial property measurements across the temperature gradient are then equivalent to independent measurements after varying temperature anneals. Accurate temperature calibrations, essential to quantitative analysis, are critical and methods for both peak temperature and spatial/temporal temperature profile characterization are presented. These include absolute temperature calibrations based on melting and thermal decomposition, and time-resolved profiles measured using platinum thermistors. A variety of spatially resolved measurement probes, ranging from point-like continuous profiling to large area sampling, are discussed. Examples from annealing of III-V semiconductors, CdSe quantum dots, low-κ dielectrics, and block copolymers are included to demonstrate the flexibility, high throughput, and precision of this technique. PMID:27385487

  14. Evolution of Safeguards over Time: Past, Present, and Projected Facilities, Material, and Budget

    SciTech Connect

    Kollar, Lenka; Mathews, Caroline E.

    2009-07-01

    This study examines the past trends and evolution of safeguards over time and projects growth through 2030. The report documents the amount of nuclear material and facilities under safeguards from 1970 until present, along with the corresponding budget. Estimates for the future amount of facilities and material under safeguards are made according to non-nuclear-weapons states’ (NNWS) plans to build more nuclear capacity and sustain current nuclear infrastructure. Since nuclear energy is seen as a clean and economic option for base load electric power, many countries are seeking to either expand their current nuclear infrastructure, or introduce nuclear power. In order to feed new nuclear power plants and sustain existing ones, more nuclear facilities will need to be built, and thus more nuclear material will be introduced into the safeguards system. The projections in this study conclude that a zero real growth scenario for the IAEA safeguards budget will result in large resource gaps in the near future.

  15. Finite element modeling of dental restoration through multi-material laser densification

    NASA Astrophysics Data System (ADS)

    Dai, Kun

    To provide guidance for intelligent selection of various parameters in the Multi-Material Laser Densification (MMLD) process for dental restorations, finite element modeling (FEM) has been carried out to investigate the MMLD process. These modeling investigations include the thermal analysis of the nominal surface temperature that should be adopted during experiments in order to achieve the desired microstructure; the effects of the volume shrinkage due to transformation from a powder compact to dense liquid on the temperature distribution and the size of the transformation zone; the evolution of transient temperature, transient stresses, residual stresses and distortions; and the effects of laser processing conditions, such as fabrication sequences, laser scanning patterns, component sizes, preheating temperatures, laser scanning rates, initial porosities, and thicknesses of each powder layer, on the final quality of the component fabricated via the MMLD process. The simulation results are compared with the experiments. It is found that the predicted temperature distribution matches the experiments very well. The nominal surface temperature applied on the dental porcelain body should be below 1273 K to prevent the forming of the un-desired microstructure (i.e., a leucite-free glassy phase). The simplified models that do not include the volume shrinkage effect provide good estimations of the temperature field and the size of the laser-densified body, although the shape of the laser-densified body predicted is different from that obtained in the experiment. It is also fount that warping and residual thermal stresses of the laser-densified component are more sensitive to the chamber preheating temperature and the thickness of each powder layer than to the laser scanning rate and the initial porosity of the powder layer. The major mechanism responsible for these phenomena is identified to be related to the change of the temperature gradient induced by these laser

  16. Modeling laser speckle imaging of perfusion in the skin (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Regan, Caitlin; Hayakawa, Carole K.; Choi, Bernard

    2016-02-01

    Laser speckle imaging (LSI) enables visualization of relative blood flow and perfusion in the skin. It is frequently applied to monitor treatment of vascular malformations such as port wine stain birthmarks, and measure changes in perfusion due to peripheral vascular disease. We developed a computational Monte Carlo simulation of laser speckle contrast imaging to quantify how tissue optical properties, blood vessel depths and speeds, and tissue perfusion affect speckle contrast values originating from coherent excitation. The simulated tissue geometry consisted of multiple layers to simulate the skin, or incorporated an inclusion such as a vessel or tumor at different depths. Our simulation used a 30x30mm uniform flat light source to optically excite the region of interest in our sample to better mimic wide-field imaging. We used our model to simulate how dynamically scattered photons from a buried blood vessel affect speckle contrast at different lateral distances (0-1mm) away from the vessel, and how these speckle contrast changes vary with depth (0-1mm) and flow speed (0-10mm/s). We applied the model to simulate perfusion in the skin, and observed how different optical properties, such as epidermal melanin concentration (1%-50%) affected speckle contrast. We simulated perfusion during a systolic forearm occlusion and found that contrast decreased by 35% (exposure time = 10ms). Monte Carlo simulations of laser speckle contrast give us a tool to quantify what regions of the skin are probed with laser speckle imaging, and measure how the tissue optical properties and blood flow affect the resulting images.

  17. Reconfigurable laser arrays with capillary fill microfluidics for chip-based flow cytometry (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Thomas, Robert

    2016-03-01

    Low cost, portable chip based flow cytometry has great potential for applications in resource poor and point of care settings. Typical approaches utilise low cost silicon or glass substrates with light emission and detection performed either off-chip using external equipment or incorporated on-chip using `pick and place' diode lasers and photo-detectors. The former approach adds cost and limits portability while the sub-micron alignment tolerances imposed by the application make the latter impractical for all but the simplest of systems. Use of an optically active semiconductor substrate, on the other hand, overcomes these limitations by allowing multiple laser/detector arrays to be formed in the substrate itself using high resolution lithographic techniques. The capacity for multiple emitters and detectors on a single chip not only enables parallel measurement for increased throughput but also allows multiple measurements to be performed on each cell as it passes through the system. Several different experiments can be performed simultaneously and throughput demand can be reduced with the facility for error checking. Furthermore, the fast switching times inherent with semiconductor lasers allows the active sections of the device to be reconfigured on a sub-microsecond time scale providing additional functionality. This is demonstrated here in a capillary fill system using pairs of laser/detectors that are operated in pulsed mode and alternated between lasing and detecting in an interleaved manner. Passing cells are alternately interrogated from opposing directions providing information that can be used to correct for differences in lateral cell position and ultimately differentiate blood cell type.

  18. Extinction characterization of soot produced by laser ablating carbon fiber composite materials in air flow

    NASA Astrophysics Data System (ADS)

    Liu, Weiping; Ma, Zhiliang; Zhang, Zhenrong; Zhou, Menglian; Wei, Chenghua

    2015-05-01

    In order to research the dynamic process of energy coupling between an incident laser and a carbon fiber/epoxy resin composite material, an extinction characterization analysis of soot, which is produced by laser ablating and located in an air flow that is tangential to the surface of the composite material, is carried out. By the theory analyses, a relationship of mass extinction coefficient and extinction cross section of the soot is derived. It is obtained that the mass extinction coefficients of soot aggregates are the same as those of the primary particles when they contain only a few primary particles. This conclusion is significant when the soot is located in an air flow field, where the generations of the big soot aggregates are suppressed. A verification experiment is designed. The experiment employs Laser Induced Incandescence technology and laser extinction method for the soot synchronization diagnosis. It can derive a temporal curve of the mass extinction coefficient from the soot concentration and laser transmittance. The experiment results show that the mass extinction coefficient becomes smaller when the air flow velocity is higher. The reason is due to the decrease of the scatter effects of the soot particles. The experiment results agree with the theory analysis conclusion.

  19. Bioactive treatment promotes osteoblast differentiation on titanium materials fabricated by selective laser melting technology.

    PubMed

    Tsukanaka, Masako; Fujibayashi, Shunsuke; Takemoto, Mitsuru; Matsushita, Tomiharu; Kokubo, Tadashi; Nakamura, Takashi; Sasaki, Kiyoyuki; Matsuda, Shuichi

    2016-01-01

    Selective laser melting (SLM) technology is useful for the fabrication of porous titanium implants with complex shapes and structures. The materials fabricated by SLM characteristically have a very rough surface (average surface roughness, Ra=24.58 µm). In this study, we evaluated morphologically and biochemically the specific effects of this very rough surface and the additional effects of a bioactive treatment on osteoblast proliferation and differentiation. Flat-rolled titanium materials (Ra=1.02 µm) were used as the controls. On the treated materials fabricated by SLM, we observed enhanced osteoblast differentiation compared with the flat-rolled materials and the untreated materials fabricated by SLM. No significant differences were observed between the flat-rolled materials and the untreated materials fabricated by SLM in their effects on osteoblast differentiation. We concluded that the very rough surface fabricated by SLM had to undergo a bioactive treatment to obtain a positive effect on osteoblast differentiation.

  20. Bioactive treatment promotes osteoblast differentiation on titanium materials fabricated by selective laser melting technology.

    PubMed

    Tsukanaka, Masako; Fujibayashi, Shunsuke; Takemoto, Mitsuru; Matsushita, Tomiharu; Kokubo, Tadashi; Nakamura, Takashi; Sasaki, Kiyoyuki; Matsuda, Shuichi

    2016-01-01

    Selective laser melting (SLM) technology is useful for the fabrication of porous titanium implants with complex shapes and structures. The materials fabricated by SLM characteristically have a very rough surface (average surface roughness, Ra=24.58 µm). In this study, we evaluated morphologically and biochemically the specific effects of this very rough surface and the additional effects of a bioactive treatment on osteoblast proliferation and differentiation. Flat-rolled titanium materials (Ra=1.02 µm) were used as the controls. On the treated materials fabricated by SLM, we observed enhanced osteoblast differentiation compared with the flat-rolled materials and the untreated materials fabricated by SLM. No significant differences were observed between the flat-rolled materials and the untreated materials fabricated by SLM in their effects on osteoblast differentiation. We concluded that the very rough surface fabricated by SLM had to undergo a bioactive treatment to obtain a positive effect on osteoblast differentiation. PMID:26830832

  1. Osteoblast cell response to a CO 2 laser modified polymeric material

    NASA Astrophysics Data System (ADS)

    Waugh, D. G.; Lawrence, J.; Brown, E. M.

    2012-02-01

    Lasers are an efficient technology, which can be applied for the surface treatment of polymeric biomaterials to enhance insufficient surface properties. That is, the surface chemistry and topography of biomaterials can be modulated to increase the biofunctionality of that material. By employing CO 2 laser patterning and whole area processing of nylon 6,6 this paper details how the surface properties were significantly modified. Samples, which had undergone whole area processing, followed the current theory in which the advancing contact angle, θ, with water decreased and the polar component, γp, increased upon an increase in surface roughness. For the patterned samples it was observed that θ increased and γP decreased. This did not follow the current theory and can be explained by a mixed-state wetting regime. By seeding osteoblast cells onto the samples for 24 h and 4 days the laser surface treatment gave rise to modulated cell response. For the laser whole area processing, θ and γP correlated with the observed cell count and cover density. Owed to the wetting regime, the patterned samples did not give rise to any correlative trend. As a result, CO 2 laser whole area processing is more likely to allow one to predict biofunctionality prior to cell seeding. Moreover, for all samples, cell differentiation was evidenced. On account of this and the modulation in cell response, it has been shown that laser surface treatment lends itself to changing the biofunctional properties of nylon 6,6.

  2. Assessment of incident intensity on laser speckle contrast imaging using a nematic liquid crystal spatial light modulator (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Kirby, Mitchell A.; Khaksari, Kosar; Kirkpatrick, Sean J.

    2016-03-01

    In this work the effects of incident intensity and effective camera dynamic range on image acquisition of both frozen and time-averaged dynamic speckle patterns, and their effects on laser speckle contrast imaging are addressed. A nematic liquid crystal, phase-only, spatial light modulator (SLM) was employed to generate laser speckle in a controlled and repeatable fashion. By addressing the calculated spatial contrast of frozen and time-averaged dynamic speckle patterns imaged across a wide range of intensities, we present a description of optimum intensity characteristics that should be observed when using LSCI. The results indicate the importance of assessing the intensity of the signal quantized by the camera in LSCI. By analyzing intensity PDF's during image acquisition of speckle patterns used in LSCI, an optimum incident intensity can be detected when a single, polarized speckle frame displays the first order statistics characteristic of fully developed speckle. Our results indicate that there is a range of laser power densities where the ensuing imaged speckle exhibit optimum sensitivity to flow as well as relatively constant calculated contrast values. It is clear that at high intensities, high frequency information is lost due to camera saturation, resulting in a decrease in contrast. When imaging speckle at low intensity, there is a risk for loss of data during the digital quantization process. The results are presented in a generalized fashion, so they should be applicable to any LSCI system, regardless of incident laser power or camera depth.

  3. Dynamic symmetrical pattern projection based laser triangulation sensor for precise surface position measurement of various material types.

    PubMed

    Žbontar, Klemen; Mihelj, Matjaž; Podobnik, Boštjan; Povše, Franc; Munih, Marko

    2013-04-20

    This paper describes a custom, material-type-independent laser-triangulation-based measurement system that utilizes a high-quality ultraviolet laser beam. Laser structuring applications demand material surface alignment regarding the laser focus position, where fabrication conditions are optimal. Robust alignment of various material types was solved by introducing dynamic symmetrical pattern projection, and a "double curve fitting" centroid detection algorithm with subsurface scattering compensation. Experimental results have shown that the measurement system proves robust to laser intensity variation, with measurement bias lower than 50 μm and standard deviation lower than ±6.3 μm for all materials. The developed probe has been integrated into a PCB prototyping system for material referencing purposes.

  4. Infrared laser irradiation of dental enamel using submicrosecond laser pulses with and without an applied water layer: effect on bond strength to restorative materials

    NASA Astrophysics Data System (ADS)

    Sarma, Anupama V.; Staninec, Michal; Le, Charles Q.; Fried, Daniel

    2004-05-01

    Previous studies have shown that during IR laser irradiation at CO2 and Er:YAG laser wavelengths, residual particles of fused non-apatite calcium phosphate phases accumulate that may inhibit adhesion to restorative materials. A layer of water added to the enamel surface before ablation prevents the accumulation of such phases. The objective of this study was to investigate the influence of laser pulse duration and wavelength with and without the added water layer on the bond strength of composite to laser prepared enamel surfaces. The surfaces of bovine enamel were irradiated by three lasers systems: a 0.5-μs Er:YSGG laser. a 25-μs Er:YAG laser and a 5-μs TEA CO2 laser operating at 9.6-μm. A motion control system and a pressurized spray system incorporating a microprocessor controlled pulsed nozzle for water delivery, were used to ensure uniform treatment of the entire surface. There was no significant reduction in the shear-bond strength of enamel to composite for the shorter erbium laser pulses if a water-spray was not used, in contrast to previous results for the 200-μs free-running Er:YAG laser in which the water-spray resulted in significantly higher bond-strengths. Shear-bond strengths for both erbium laser systems were significantly higher than for the CO2 laser irradiated samples and the negative control (no acid-etch) but significantly lower than the positive control group (phosphoric acid-etch). The application of the water-spray markedly influenced the surface morphology for all three laser systems with the most uniform surface preparation being produced by the 25-μs Er:YAG laser and the 5-μs CO2 laser with the water-spray.

  5. Nuclear power plant containment metallic pressure boundary materials and plans for collecting and presenting their properties

    SciTech Connect

    Oland, C.B.

    1995-04-01

    A program is being conducted at the Oak Ridge National Laboratory (ORNL to assist the Nuclear Regulatory Commission (NRC)) in their assessment of the effects of degradation (primarily corrosion) on the structural capacity and leaktight integrity of metal containments and steel liners of reinforced concrete structures in nuclear power plants. One of the program objectives is to characterize and quantify manifestations of corrosion on the properties of steels used to construct containment pressure boundary components. This report describes a plan for use in collecting and presenting data and information on ferrous alloys permitted for use in construction of pressure retaining components in concrete and metal containments. Discussions about various degradation mechanisms that could potentially affect the mechanical properties of these materials are also included. Conclusions and recommendations presented in this report will be used to guide the collection of data and information that will be used to prepare a material properties data base for containment steels.

  6. Bibliography of reports, papers, and presentations on naturally occurring radioactive material (NORM) in petroleum industry wastes

    SciTech Connect

    Smith, K.P.; Wilkey, M.L.; Hames, R.D.

    1997-07-01

    This bibliography was created to support projects conducted by Argonne National Laboratory (ANL) addressing issues related to naturally occurring radioactive material (NORM) in petroleum industry wastes. The bibliography provides citations for many of the available published reports, papers, articles, and presentations on petroleum industry NORM. In the past few years, the rapid expansion of NORM treatment and disposal technologies, the efforts to characterize NORM wastes and their associated potential risks, and the promulgation of state-level NORM regulatory programs have been well-documented in project reports and in papers presented at technical conferences and symposia. There are 221 citations.

  7. Note: Measurement of saturable absorption by intense vacuum ultraviolet free electron laser using fluorescent material

    SciTech Connect

    Inubushi, Y.; Kumagai, T.; Morimoto, S.; Tanaka, T.; Kodama, R.; Yoneda, H.; Higashiya, A.; Ishikawa, T.; Nagasono, M.; Tono, K.; Yabashi, M.; Kimura, H.; Ohashi, H.; Togashi, T.; Sato, F.; Yamaguchi, Y.

    2010-03-15

    Advances in free electron lasers (FELs) which generate high energy photons are expected to open novel nonlinear optics in the x-ray and vacuum ultraviolet (VUV) regions. In this paper, we report a new method for performing VUV-FEL focusing experiments. A VUV-FEL was focused with Kirkpatrick-Baez optics on a multilayer target, which contains fused silica as a fluorescent material. By measuring the fluorescence, a 5.6x4.9 {mu}m{sup 2} focal spot was observed in situ. Fluorescence was used to measure the saturable absorption of VUV pulses in the tin layer. The transmission increases nonlinearly higher with increasing laser intensity.

  8. A history of semi-active laser dome and window materials

    NASA Astrophysics Data System (ADS)

    Sullivan, Roger M.

    2014-05-01

    Semi-Active Laser (SAL) guidance systems were developed starting in the mid-1960's and today form an important class of precision guided weapons. The laser wavelengths generally fall in the short wave infrared region of the spectrum. Relative to passive, image based, infrared seekers the optical demands placed on the domes or windows of SAL seekers is very modest, allowing the use of low cost, easily manufactured materials, such as polycarbonate. This paper will examine the transition of SAL window and dome science and technology from the laboratory to battlefield, with special emphasis on the story of polycarbonate domes.

  9. Laser ablation in liquids as a new technique of sampling in elemental analysis of solid materials

    NASA Astrophysics Data System (ADS)

    Muravitskaya, E. V.; Rosantsev, V. A.; Belkov, M. V.; Ershov-Pavlov, E. A.; Klyachkovskaya, E. V.

    2009-02-01

    Laser ablation in liquid media is considered as a new sample preparation technique in the elemental composition analysis of materials using optical emission spectroscopy of inductively coupled plasma (ICP-OES). Solid samples are transformed into uniform colloidal solutions of nanosized analyte particles using laser radiation focused onto the sample surface. High homogeneity of the resulting solution allows performing the ICP-OES quantitative analysis especially for the samples, which are poorly soluble in acids. The technique is compatible with the conventional solution-based standards.

  10. Laser-Induced Surface Damage of Optical Materials: Absorption Sources, Initiation, Growth, adn Mitigation

    SciTech Connect

    Papernov, S.; Schmid, A.W.

    2009-04-07

    Susceptibility to laser damage of optical-material surfaces originates from the nature of the surface as a transitional structure between optical-material bulk and its surroundings. As such, it requires technological processing to satisfy figure and roughness requirements and is also permanently subjected to environmental exposure. Consequently, enhanced absorption caused by mechanical structural damage or incorporation and sorption of microscale absorbing defects, even layers of organic materials, is always characteristic for optical-material surfaces. In this review physics of interaction of pulsed-laser radiation with surface imperfections for different types of optical materials (metals, semiconductors, dielectrics, etc.), mechanisms of damage initiation, damage morphology, and damage-site growth under repetitive pulse irradiation are discussed. Consideration is also given here to the surface treatments leading to the reduction of damage initiation sites, such as laser cleaning and conditioning, removal of the surface layers affected by the grinding/polishing process, and mitigation of the damage growth at already formed damage sites.

  11. Power scaling analysis of fiber lasers and amplifiers based on non-silica materials

    SciTech Connect

    Dawson, J W; Messerly, M J; Heebner, J E; Pax, P H; Sridharan, A K; Bullington, A L; Beach, R J; Siders, C W; Barty, C P; Dubinskii, M

    2010-03-30

    A developed formalism for analyzing the power scaling of diffraction limited fiber lasers and amplifiers is applied to a wider range of materials. Limits considered include thermal rupture, thermal lensing, melting of the core, stimulated Raman scattering, stimulated Brillouin scattering, optical damage, bend induced limits on core diameter and limits to coupling of pump diode light into the fiber. For conventional fiber lasers based upon silica, the single aperture, diffraction limited power limit was found to be 36.6kW. This is a hard upper limit that results from an interaction of the stimulated Raman scattering with thermal lensing. This result is dependent only upon physical constants of the material and is independent of the core diameter or fiber length. Other materials will have different results both in terms of ultimate power out and which of the many limits is the determining factor in the results. Materials considered include silica doped with Tm and Er, YAG and YAG based ceramics and Yb doped phosphate glass. Pros and cons of the various materials and their current state of development will be assessed. In particular the impact of excess background loss on laser efficiency is discussed.

  12. Power scaling analysis of fiber lasers and amplifiers based on non-silica materials

    NASA Astrophysics Data System (ADS)

    Dawson, Jay W.; Messerly, Michael J.; Heebner, John E.; Pax, Paul H.; Sridharan, Arun K.; Bullington, Amber L.; Beach, Raymond J.; Siders, Craig W.; Barty, C. P. J.; Dubinskii, Mark

    2010-04-01

    A developed formalism1 for analyzing the power scaling of diffraction limited fiber lasers and amplifiers is applied to a wider range of materials. Limits considered include thermal rupture, thermal lensing, melting of the core, stimulated Raman scattering, stimulated Brillouin scattering, optical damage, bend induced limits on core diameter and limits to coupling of pump diode light into the fiber. For conventional fiber lasers based upon silica, the single aperture, diffraction limited power limit was found to be 36.6kW. This is a hard upper limit that results from an interaction of the stimulated Raman scattering with thermal lensing. This result is dependent only upon physical constants of the material and is independent of the core diameter or fiber length. Other materials will have different results both in terms of ultimate power out and which of the many limits is the determining factor in the results. Materials considered include silica doped with Tm and Er, YAG and YAG based ceramics and Yb doped phosphate glass. Pros and cons of the various materials and their current state of development will be assessed. In particular the impact of excess background loss on laser efficiency is discussed.

  13. Laser-assisted metal spinning for an efficient and flexible processing of challenging materials

    NASA Astrophysics Data System (ADS)

    Brummer, C.; Eck, S.; Marsoner, S.; Arntz, K.; Klocke, F.

    2016-03-01

    The demand for components made from high performance materials like titanium or nickel-based alloys as well as strain-hardening stainless steel is steadily increasing. However, conventional forming operations conducted on these materials are generally very laborious and time-consuming. This is where the limitations of metal spinning also become apparent. Using a laser to apply heat localized to the forming zone during metal spinning facilitates to enhance the formability of a material. In order to analyse the potential of the new manufacturing process, experimental investigations on laser-assisted shear forming and multi-pass metal spinning have been performed with austenitic stainless steel X5CrNi18-10, nickel-based alloy Inconel 718 and titanium grade 2. It could be demonstrated that the formability of these materials can be enhanced by laser-assistance. Besides the resulting enhancement of forming limits for metal spinning of challenging materials, the forming forces were reduced and the product quality was improved significantly.

  14. Mercury Bromide (HgBr{sub 2}): A promising nonlinear optical material in IR region with a high laser damage threshold

    SciTech Connect

    Liu, T.; Zhang, G.; Zhu, T.; Niu, F.; Qin, J.; Wu, Y.; Chen, C.

    2008-09-01

    Nonlinear optical (NLO) crystals have played a key role in laser technology, and the existing materials for the IR range showed relatively low laser damage threshold in common. A NLO material HgBr{sub 2} is presented here. It shows a powder second harmonic generation about ten times as large as that of KH{sub 2}PO{sub 4}, a wide transparency in whole mid-IR region (from 2.5 to 25 {mu}m), and a good stability to the environment. Most importantly it exhibits a high laser damage threshold of about 0.3 GW/cm{sup 2}. Therefore, it is believed that HgBr{sub 2} is a promising candidate for NLO materials in the IR region.

  15. Advanced Laser-Compton Gamma-Ray Sources for Nuclear Materials Detection, Assay and Imaging

    NASA Astrophysics Data System (ADS)

    Barty, C. P. J.

    2015-10-01

    Highly-collimated, polarized, mono-energetic beams of tunable gamma-rays may be created via the optimized Compton scattering of pulsed lasers off of ultra-bright, relativistic electron beams. Above 2 MeV, the peak brilliance of such sources can exceed that of the world's largest synchrotrons by more than 15 orders of magnitude and can enable for the first time the efficient pursuit of nuclear science and applications with photon beams, i.e. Nuclear Photonics. Potential applications are numerous and include isotope-specific nuclear materials management, element-specific medical radiography and radiology, non-destructive, isotope-specific, material assay and imaging, precision spectroscopy of nuclear resonances and photon-induced fission. This review covers activities at the Lawrence Livermore National Laboratory related to the design and optimization of mono-energetic, laser-Compton gamma-ray systems and introduces isotope-specific nuclear materials detection and assay applications enabled by them.

  16. Gold nanoparticle plasmonics enhanced ultrafast laser-induced optoporation and stimulation of targeted cells (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Meunier, Michel; Bergeron, Éric; Lavoie-Cardinal, Flavie; Boutopoulos, Christos; Salesse, Charleen; Winnik, Françoise M.; De Koninck, Paul

    2016-03-01

    Gold nanoparticles (AuNPs) have found numerous applications in nanomedicine in view of their robustness, ease of functionalization and low toxicity. Upon irradiation of AuNPs by a pulsed ultrafast laser, various highly localized phenomena can be obtained including a temperature rise, pressure wave, charge injection and production of nanobubbles close to the cellular membrane [1]. These phenomena can be used to manipulate, optoperforate, transfect and stimulate targeted cells [2-5]. Irradiating at 800 nm in the optically biological transparent window, we demonstrated local optoporation and transfection of cells as well as local stimulation of neurons. Two recent examples will be given: (i) Laser-induced selective optoporation of cells: The technique can be used on various types of cells and a proof of principle will be given on human cancer cells in a co-culture using functionalized AuNPs [6]. (ii) Laser-induced stimulation of neurons and monitoring of the localized Ca2+ signaling: This all optical method uses a standard confocal microscope to trigger a transient increase in free Ca2+ in neurons covered by functionalized AuNPs as well as to measure these local variations optically with the Ca2+ sensor GCaMP6s [7]. The proposed techniques provide a new complement to light-dependent methods in neuroscience. REFERENCES (by our group): (1) Boulais, J. Photochem. Photobiol. C Photochem. Rev. 17, 26 (2013); (2) Baumgart, Biomaterials 33, 2345 (2012); (3) Boulais, NanoLett. 12, 4763 (2012); (4) Boutopoulos, J. Biophotonics (2015); (5) Boutopoulos, Nanoscale 7, 11758 (2015); (6) Bergeron, Biomaterials, submitted (2015); (7) Lavoie-Cardinal, Nature Commun. submitted (2015).

  17. Advances in laser ablation MC-ICPMS isotopic analysis of rock materials

    NASA Astrophysics Data System (ADS)

    Young, E. D.

    2007-12-01

    single-step equilibrium processes to 0.510 or even lower for kinetic processes. Rayleigh fractionation involving a kinetic process with a single-step β of 0.510 produces an effective β of 0.512. Such differences in fractionation laws can be crucial for determining excesses or deficits in isotopes relative to mass fractionation. Contrary to some assertions, Si isotope ratios can be measured with high accuracy and precision using 193 nm excimer lasers with nanosecond pulse widths (Shahar and Young, 2007). Silicon isotope ratios in CAIs measured by 193 nm LA-MC-ICPMS have been combined with Mg isotope ratios to constrain the astrophysical environments in which these oldest solar system materials formed. Accuracy of the measurements was determined using gravimetric standards of various matrix compositions. The results establish that matrix effects for Si are below detection at the ± 0.2 ‰ precision of the laser ablation technique. High mass resolving power (m/Δ m ~ 9000) is necessary to obtain accurate Si isotope ratios by laser ablation. High-precision LA-MC-ICPMS measurements of 176Hf/177Hf in zircons can be obtained by normalizing to 179Hf/177Hf assuming an exponential fractionation law and no mass-dependent Hf, Lu, or Yb stable isotope fractionation. With corrections for interfering 176Lu and 176Yb precision for this method can be on the order of 0.3 epsilon (0.03 ‰). The approach has been used to infer the existence of continental crust on Earth 4.4 billion years before present (Harrison et al., 2005).

  18. Present status and strategic plan for the stable isotope reference materials at the IAEA.

    NASA Astrophysics Data System (ADS)

    Assonov, Sergey; Groening, Manfred

    2016-04-01

    The presentation will give the overview of the stable isotope reference materials (SI-RMs) under distribution by the IAEA, its stable isotope laboratory and capacities related to material testing & production as well as future plans. Historically, most of the IAEA reference materials were produced and made available via collaborations with expert stable isotope laboratories worldwide. The IAEA plans include several directions as follows: • Maintaining the scale-defining SI-RMs at the highest level and introducing adequate replacements when needed; • Monitoring existing SI-RMs for any potential alteration(s) and of isotopic values assigned; • Identifying and then addressing the needs for new SI-RMs, with the priority to address the most critical applications (environmental and climate related applications, human health, food safety studies) and newly emerging analytical isotope techniques; • Performing all measurements aimed for characterisation of new SI-RMs and the corresponding uncertainty evaluation in accordance to the latest metrological concepts; • Promoting metrological approaches on traceability and uncertainty evaluation in every day practice of stable isotope measurements; • Expanding the IAEA capacities for SI-RMs by (i) planning a renewed laboratory at IAEA; (ii) enlarging collaboration with expert laboratories aimed to help IAEA in production and characterisation of new SI-RMs. These major directions will help to address the increasing demand for Stable Isotope Reference Materials.

  19. High-resolution chemical depth profiling of solid material using a miniature laser ablation/ionization mass spectrometer.

    PubMed

    Grimaudo, Valentine; Moreno-García, Pavel; Riedo, Andreas; Neuland, Maike B; Tulej, Marek; Broekmann, Peter; Wurz, Peter

    2015-02-17

    High-resolution chemical depth profiling measurements of copper films are presented. The 10 μm thick copper test samples were electrodeposited on a Si-supported Cu seed under galvanostatic conditions in the presence of particular plating additives (SPS, Imep, PEI, and PAG) used in the semiconductor industry for the on-chip metallization of interconnects. To probe the trend of these plating additives toward inclusion into the deposit upon growth, quantitative elemental mass spectrometric measurements at trace level concentration were conducted by using a sensitive miniature laser ablation ionization mass spectrometer (LIMS), originally designed and developed for in situ space exploration. An ultrashort pulsed laser system (τ ∼ 190 fs, λ = 775 nm) was used for ablation and ionization of sample material. We show that with our LIMS system, quantitative chemical mass spectrometric analysis with an ablation rate at the subnanometer level per single laser shot can be conducted. The measurement capabilities of our instrument, including the high vertical depth resolution coupled with high detection sensitivity of ∼10 ppb, high dynamic range ≥10(8), measurement accuracy and precision, is of considerable interest in various fields of application, where investigations with high lateral and vertical resolution of the chemical composition of solid materials are required, these include, e.g., wafers from semiconductor industry or studies on space weathered samples in space research.

  20. Pressure effects in the electronic levels of tunable laser materials

    NASA Astrophysics Data System (ADS)

    Lemos, V.

    1999-07-01

    The low to high-field transition in KZnF3:Cr3+, induced by external pressure was observed through photoluminescence measurements at room temperature, T equals 90 K and T equals 20 K. Direct measurement of the lowest electronic level separation (Delta) , was accomplished through the low temperature experiments. Pressure coefficients of (Delta) are given. Emission spectra of KZnF3:Cr3+ obtained at several pressures and temperatures in the range [20 K - 90 K] allow for the construction of a Tanabe-Sugano type diagram illustrating the transition from low- to high-crystal-field regime for cubic and distorted centers. Assignments of sharp lines are given based on the analysis of these diagrams, time-resolved spectroscopy and transition lifetime. Emission measurements were performed at atmospheric pressure and low temperature outside the pressure cell and also at several pressures for KZnF3:Co3+. Comparing the zero-phonon line positions and using the phonon dispersion relation of the host material and fine structure in the emission spectrum of KZnF3:Co2+ was identified. Pressure coefficients were obtained for several among the emission lines from which the values for zero-phonon lines were deduced. Analysis show that the spin-orbit parameter changes with pressure are negligible in KZnF3:Co2+.

  1. Feasibility of laser pumping with neutron fluxes from present-day large tokamaks

    SciTech Connect

    Jassby, D.L.

    1986-08-01

    The minimum fusion-neutron flux needed to observe nuclear-pumped lasing with tokamaks can be reduced substantially by optimizing neutron scattering into the laser cell, located between adjacent toroidal-field coils. The laser lines most readily pumped are probably the /sup 3/He-Ne lines at 0.633 ..mu.. and in the infrared, where the /sup 3/He-Ne gas is excited by energetic ions produced in the /sup 3/He(n,p)T reaction. These lines are expected to lase at the levels of D-T neutron flux foreseen for the TFTR in 1989 (>>10/sup 12/ n/cm/sup 2//s), while amplification should be observable at the existing levels of D-D neutron flux (greater than or equal to 5 x 10/sup 9/ n/cm/sup 2//s). Lasing on the 1.73 ..mu.. and 2.63 ..mu.. transitions of Xe may be observable at the maximum expected levels of D-T neutron flux in TFTR enhanced by scattering.

  2. Laser dosimetry for disabling anopheles stephensi mosquitoes in-flight (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Keller, Matthew D.; Norton, Bryan J.; Rutschman, Phil; Farrar, David J.; Marvit, Maclen; Makagon, Artyom

    2016-03-01

    The Photonic Fence is a system designed to detect mosquitoes and other pestilent flying insects in an active region and to apply lethal doses of laser light to them. Previously, we determined lethal fluence levels for a variety of lasers and pulse conditions on anesthetized Anopheles stephensi mosquitoes. In this work, similar studies were performed while the bugs were freely flying within transparent cages. Dose-response curves were created for various beam diameter, pulse width, and power conditions at 455 nm, 532 nm, 1064nm, and 1540 nm wavelengths. Besides mortality outcomes, the flight behavior of the bugs and the performance of the tracking system were monitored for consistency and to ensure that they had no impact on the mortality outcomes. As in anesthetized experiments, the visible wavelengths required significantly less fluence than near infrared wavelengths to reliably disable bugs. For the visible wavelengths, lethal fluence values were generally equivalent to those found in anesthetized dosing, while near infrared wavelengths required approximately twice the fluence compared with anesthetized experiments. The performance of the optical tracking system remained highly stable throughout the experiments, and it was found not to influence mortality results for pulse widths up to 25 ms. In general, keeping energy constant while decreasing power and increasing pulse width reduced mortality levels. The results of this study further affirm the practicality of using optical approaches to protect people and crops from flying insects.

  3. Surface modification during Nd:YAG (1064 nm) pulsed laser cleaning of organic fibrous materials

    NASA Astrophysics Data System (ADS)

    Strlič, Matija; Kolar, Jana; Šelih, Vid-Simon; Marinček, Marko

    2003-02-01

    Formation of yellow chromophores on artificially soiled surfaces of cellulose sheets, rag paper, linen, cotton, wool and silk during Nd:YAG (1064 nm) pulsed laser cleaning was followed using Vis and FTIR diffuse reflectance spectrometry. Content of reducing carbonyl groups and changes in FTIR reflectance spectra of cellulose are indicative of surface chemical modifications typical of thermal degradation at elevated temperatures. Two types of soiling were used: well-characterised natural dust and carbon powder and no difference in laser-induced formation of chromophores on material surface was observed at low deposit densities. The influence of laser fluence and number of repetitions was studied and a single pulse of a higher fluence (1 J cm -1) is in general more advisable. No bleaching of the chromophores formed was noticed after repeated treatments.

  4. Graphene Oxides as Tunable Broadband Nonlinear Optical Materials for Femtosecond Laser Pulses.

    PubMed

    Jiang, Xiao-Fang; Polavarapu, Lakshminarayana; Neo, Shu Ting; Venkatesan, T; Xu, Qing-Hua

    2012-03-15

    Graphene oxide (GO) thin films on glass and plastic substrates were found to display interesting broadband nonlinear optical properties. We have investigated their optical limiting activity for femtosecond laser pulses at 800 and 400 nm, which could be tuned by controlling the extent of reduction. The as-prepared GO films were found to exhibit excellent broadband optical limiting behaviors, which were significantly enhanced upon partial reduction by using laser irradiation or chemical reduction methods. The laser-induced reduction of GO resulted in enhancement of effective two-photon absorption coefficient at 400 nm by up to ∼19 times and enhancement of effective two- and three-photon absorption coefficients at 800 nm by ∼12 and ∼14.5 times, respectively. The optical limiting thresholds of partially reduced GO films are much lower than those of various previously reported materials. Highly reduced GO films prepared by using the chemical method displayed strong saturable absorption behavior.

  5. Double-pulse machining as a technique for the enhancement of material removal rates in laser machining of metals

    SciTech Connect

    Forsman, A.C.; Banks, P.S.; Perry, M.D.; Campbell, E.M.; Dodell, A.L.; Armas, M.S.

    2005-08-01

    Several nanosecond 0.53-{mu}m laser pulses separated by several tens of nanoseconds have been shown to significantly enhance (three to ten times) material removal rates while minimizing redeposition and heat-affected zones. Economic, high-quality, high-aspect ratio holes (>10:1) in metals are produced as a result. A phenomenological model whereby the second laser pulse interacts with the ejecta produced by the first laser pulse and in close proximity to the material surface is consistent with the observations. Incident laser wavelengths of 1.05 and 0.35 {mu}m also benefit from this pulse format.

  6. Ablation by-products of dental materials from the Er:YAG laser and the dental handpiece

    NASA Astrophysics Data System (ADS)

    Wigdor, Harvey A.; Visuri, Steven R.; Walsh, Joseph T., Jr.

    1995-05-01

    Recently there has been much interest in lasers and their potential use to replace the dental drill. The research has been directed towards vital dental tissues. It must be understood that any laser to be used in dentistry which will replace the dental drill must also ablate and remove existing dental materials. Some concern exists about the ablation products when the Er:YAG laser is used to ablate dental materials. It is incumbent on the professionals using these lasers to understand the materials being produced by these lasers and protect themselves and their patients from possible toxic products. It is the intent of this paper to evaluate the products produced by the ablation of both dental amalgam and composite dental restorative materials and compare them with those produced by the traditional dental handpiece (drill).

  7. Investigating the formation mechanism of soot-like materials present in blast furnace coke samples

    SciTech Connect

    S. Dong; P. A'lvarez; N. Paterson; D.R. Dugwell; R. Kandiyoti

    2008-09-15

    An attempt to gain an understanding of the formation mechanism of these 'soot-like' materials has been made by means of tracing the changes in the molecular-mass distribution and molecular structure of the NMP-extractable materials from an injectant coal as well as its partially gasified chars and its pyrolytic tars. Variations in the SEC chromatograms provide clues about changes in the apparent molecular-mass distributions of these NMP extracts. Results suggest that the build-up of 'soot-like' materials follows from the secondary reactions of tars evolved from the injectant coal. The likely secondary-reaction pathways have been probed by collating structural information on these NMP extracts. The time-resolved 13-16 and 22-25 min elution fractions from the SEC column have been characterized using UV fluorescence (UV F) spectroscopy. Greater concentrations of larger aromatic ring systems are found present in samples formed under conditions appearing more prone for soot formation. The 11-16 min (large apparent molecular mass) effluent from SEC has been examined by Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM). Results from FTIR spectroscopy are consistent with the UV F data, showing more significant extents of dehydrogenation under conditions more prone to form soot. Similarly, TEM results show that larger amount of graphene layers exist in samples exposed to more soot-prone conditions. The emerging picture for the formation of 'soot-like' materials involves a well-defined sequence. Tars evolved from the injectant coal undergo secondary dehydrogenation, condensation, and repolymerization reactions, which eventually lead to the formation of the NMP-extractable 'soot-like' materials of large apparent molecular mass. 44 refs., 7 figs., 3 tabs.

  8. Examination of an Optical Transmittance Test for Photovoltaic Encapsulation Materials (Presentation)

    SciTech Connect

    Miller, D.; Bengoechea, J.; Bokria, J.; Kohl, M.; Powell, N. E.; Smith, M. E.; White, M. D.; Wilson, H. R.; Wohlgemuth, J. H.

    2013-09-01

    The optical transmittance of encapsulation materials is a key characteristic for their use in photovoltaic (PV) modules. Changes in transmittance with time in the field affect module performance, which may impact product warranties. Transmittance is important in product development, module manufacturing, and field power production (both immediate and long-term). Therefore, an international standard (IEC 62788-1-4) has recently been proposed by the Encapsulation Task-Group within the Working Group 2 (WG2) of the International Electrotechnical Commission (IEC) Technical Committee 82 (TC82) for the quantification of the optical performance of PV encapsulation materials. Existing standards, such as ASTM E903, are general and more appropriately applied to concentrated solar power than to PV. Starting from the optical transmittance measurement, the solar-weighted transmittance of photon irradiance, yellowness index (which may be used in aging studies to assess durability), and ultraviolet (UV) cut-off wavelength may all be determined using the proposed standard. The details of the proposed test are described. The results of a round-robin experiment (for five materials) conducted at seven laboratories to validate the test procedure using representative materials are also presented. For example, the Encapsulation Group actively explored the measurement requirements (wavelength range and resolution), the requirements for the spectrophotometer (including the integrating sphere and instrument accessories, such as a depolarizer), specimen requirements (choice of glass-superstrate and -substrate), and data analysis (relative to the light that may be used in the PV application). The round-robin experiment identified both intra- and inter-laboratory instrument precision and bias for five encapsulation materials (encompassing a range of transmittance and haze-formation characteristics).

  9. Investigation of cell proliferative activity on the surface of the nanocomposite material produced by laser radiation

    NASA Astrophysics Data System (ADS)

    Zhurbina, N. N.; Kurilova, U. E.; Ickitidze, L. P.; Podgaetsky, V. M.; Selishchev, S. V.; Suetina, I. A.; Mezentseva, M. V.; Eganova, E. M.; Pavlov, A. A.; Gerasimenko, A. Y.

    2016-04-01

    A new method for the formation of composite nanomaterials based on multi-walled and single-walled carbon nanotubes (CNT) on a silicon substrate has been developed. Formation is carried out by ultrasound coating of a silicon substrate by homogenous dispersion of CNTs in the albumin matrix and further irradiation with the continuous laser beam with a wavelength of 810 nm and power of 5.5 watts. The high electrical conductivity of CNTs provides its structuring under the influence of the laser radiation electric field. The result is a scaffold that provides high mechanical strength of nanocomposite material (250 MPa). For in vitro studies of materials biocompatibility a method of cell growth microscopic analysis was developed. Human embryonic fibroblasts (EPP) were used as biological cells. Investigation of the interaction between nanocomposite material and cells was carried out by optical and atomic force microscopy depending on the time of cells incubation. The study showed that after 3 hours incubation EPP were fixed on the substrate surface, avoiding the surface of the composite material. However, after 24 hours of incubation EPP fix on the sample surface and then begin to grow and divide. After 72 hours of incubation, the cells completely fill the sample surface of nanocomposite material. Thus, a nanocomposite material based on CNTs in albumin matrix does not inhibit cell growth on its surface, and favours their growth. The nanocomposite material can be used for creating soft tissue implants

  10. Laser-solid interaction and dynamics of laser-ablated materials

    SciTech Connect

    Chen, K.R.; Neboeuf, J.N.; Wood, R.F.; Geohegan, D.B.; Donato, J.M.; Liu, C.L.; Puretzky, A.A.

    1995-09-01

    An annealing model is extended to treat the vaporization process, and a hydrodynamic model describes the ablated material. We find that dynamic source and ionization effects accelerate the expansion front of the ablated plume with thermal vaporization temperature. The vaporization process and plume propagation in high background gas pressure are studied.

  11. Determination of trace metals using laser induced breakdown spectroscopy in insoluble organic materials obtained from pyrolysis of plastics waste.

    PubMed

    Siddiqui, Mohammad N; Gondal, Mohammad A; Nasr, Mohammed M

    2009-07-01

    Laser induced breakdown spectroscopy (LIBS) was applied for the detection of trace elements in non-degradable part of plastics known as insoluble organic material, obtained from thermal and catalytic degradation of plastics. LIBS signal intensity for each metal measured in the test sample was unique and different. The capability of this technique is demonstrated by analyzing various trace metals present inside plastics and also compared with ICP results. The metal concentration (ppm) measured with LIBS and verified by ICP for Ag (901), Al (522), Fe (231), Co (628), V (275), Ni (558), Pb (325), Mn (167) and Cd (378) are higher than permissible safe limits.

  12. Determination of trace metals using laser induced breakdown spectroscopy in insoluble organic materials obtained from pyrolysis of plastics waste.

    PubMed

    Siddiqui, Mohammad N; Gondal, Mohammad A; Nasr, Mohammed M

    2009-07-01

    Laser induced breakdown spectroscopy (LIBS) was applied for the detection of trace elements in non-degradable part of plastics known as insoluble organic material, obtained from thermal and catalytic degradation of plastics. LIBS signal intensity for each metal measured in the test sample was unique and different. The capability of this technique is demonstrated by analyzing various trace metals present inside plastics and also compared with ICP results. The metal concentration (ppm) measured with LIBS and verified by ICP for Ag (901), Al (522), Fe (231), Co (628), V (275), Ni (558), Pb (325), Mn (167) and Cd (378) are higher than permissible safe limits. PMID:19421698

  13. Laser Welding Characterization of Kovar and Stainless Steel Alloys as Suitable Materials for Components of Photonic Devices Packaging

    NASA Astrophysics Data System (ADS)

    Fadhali, M. M. A.; Zainal, Saktioto J.; Munajat, Y.; Jalil, A.; Rahman, R.

    2010-03-01

    The weldability of Kovar and stainless steel alloys by Nd:YAG laser beam is studied through changing of some laser beam parameters. It has been found that there is a suitable interaction of the pulsed laser beam of low power laser pulse with both the two alloys. The change of thermophysical properties with absorbed energy from the laser pulse is discussed in this paper which reports the suitability of both Kovar and stainless steel 304 as the base materials for photonic devices packaging. We used laser weld system (LW4000S from Newport) which employs Nd:YAG laser system with two simultaneous beams output for packaging 980 nm high power laser module. Results of changing both laser spot weld width and penetration depth with changing both the pulse peak power density, pulse energy and pulse duration show that there are good linear relationships between laser pulse energy or peak power density and pulse duration with laser spot weld dimensions( both laser spot weld width and penetration depth). Therefore we concluded that there should be an optimization for both the pulse peak power and pulse duration to give a suitable aspect ratio (laser spot width to penetration depth) for achieving the desired welds with suitable penetration depth and small spot width. This is to reduce the heat affected zone (HAZ) which affects the sensitive optical components. An optimum value of the power density in the order of 105 w/cm2 found to be suitable to induce melting in the welded joints without vaporization. The desired ratio can also be optimized by changing the focus position on the target material as illustrated from our measurements. A theoretical model is developed to simulate the temperature distribution during the laser pulse heating and predict the penetration depth inside the material. Samples have been investigated using SEM with EDS. The metallographic measurements on the weld spot show a suitable weld yield with reasonable weld width to depth ratio.

  14. Dynamic materials evaluation by confined plasma ablation and laser-generated shocks

    NASA Astrophysics Data System (ADS)

    Paisley, Dennis L.; Swift, D. C.; Forsman, A. C.; Kyrala, George A.; Johnson, Randall P.; Kopp, Roger A.; Hauer, Allan A.; Wark, Justin S.; Loveridge, A.; Allen, A. M.; Kalantar, Daniel H.

    2000-08-01

    Laser-generated shocks can and have been used to study their effects on single crystal materials during shock compression. While a crystal undergoes shock compression and release, the transient x- ray diffraction (TXD) of the Bragg and Laue signals is indicative of the change in the crystal lattice spacing. The lattice spacing directly relates to the strain in the crystal. From the dynamic lattice data, strain, strain rate, and/or phase change in a material may be determined. Confined ablation plasmas can efficiently launch a flyer plate for direct impact on a target material imparting a well-characterized shock input and generate kilobar to megabar pressure pulses over a wide range of pulse duration (= 20 ns). The laser-launched flyer plates are analogous to those launched by gas guns, but the smaller size provides an experimental method not easily accessible by larger gas gun experiments. With lasers, diagnostic equipment can be easily synchronized to study dynamic material parameters, i.e., single crystal shock dynamics, interfacial bond strengths of thin coatings, grain-interfaces, texture, and high strain rates (106 - 109 sec-1).

  15. Indirect Versus Direct Heating of Sheet Materials: Superplastic Forming and Diffusion Bonding Using Lasers

    NASA Astrophysics Data System (ADS)

    Jocelyn, Alan; Kar, Aravinda; Fanourakis, Alexander; Flower, Terence; Ackerman, Mike; Keevil, Allen; Way, Jerome

    2010-06-01

    Many from within manufacturing industry consider superplastic forming (SPF) to be ‘high tech’, but it is often criticized as too complicated, expensive, slow and, in general, an unstable process when compared to other methods of manipulating sheet materials. Perhaps, the fundamental cause of this negative perception of SPF, and also of diffusion bonding (DB), is the fact that the current process of SPF/DB relies on indirect sources of heating to produce the conditions necessary for the material to be formed. Thus, heat is usually derived from the electrically heated platens of hydraulic presses, to a lesser extent from within furnaces and, sometimes, from heaters imbedded in ceramic moulds. Recent evaluations of these isothermal methods suggest they are slow, thermally inefficient and inappropriate for the process. In contrast, direct heating of only the material to be formed by modern, electrically efficient, lasers could transform SPF/DB into the first choice of designers in aerospace, automotive, marine, medical, architecture and leisure industries. Furthermore, ‘variable temperature’ direct heating which, in theory, is possible with a laser beam(s) may provide a means to control material thickness distribution, a goal of enormous importance as fuel efficient, lightweight structures for transportation systems are universally sought. This paper compares, and contrasts, the two systems and suggests how a change to laser heating might be achieved.

  16. Imaging Fourier transform spectroscopy of the boundary layer plume from laser irradiated polymers and carbon materials

    NASA Astrophysics Data System (ADS)

    Acosta, Roberto I.

    The high-energy laser (HEL) lethality community needs for enhanced laser weapons systems requires a better understanding of a wide variety of emerging threats. In order to reduce the dimensionality of laser-materials interaction it is necessary to develop novel predictive capabilities of these events. The objective is to better understand the fundamentals of laser lethality testing by developing empirical models from hyperspectral imagery, enabling a robust library of experiments for vulnerability assessments. Emissive plumes from laser irradiated fiberglass reinforced polymers (FRP), poly(methyl methacrylate) (PMMA) and porous graphite targets were investigated primarily using a mid-wave infrared (MWIR) imaging Fourier transform spectrometer (FTS). Polymer and graphite targets were irradiated with a continuous wave (cw) fiber lasers. Data was acquired with a spectral resolution of 2 cm-1 and spatial resolution as high as 0.52 mm2 per pixel. Strong emission from H2O, CO, CO2 and hydrocarbons were observed in the MWIR between 1900-4000 cm-1. A single-layer radiative transfer model was developed to estimate spatial maps of temperature and column densities of CO and CO2 from the hyperspectral imagery of the boundary layer plume. The spectral model was used to compute the absorption cross sections of CO and CO2, using spectral line parameters from the high temperature extension of the HITRAN. Also, spatial maps of gas-phase temperature and methyl methacrylate (MMA) concentration were developed from laser irradiated carbon black-pigmented PMMA at irradiances of 4-22 W/cm2. Global kinetics interplay between heterogeneous and homogeneous combustion kinetics are shown from experimental observations at high spatial resolutions. Overall the boundary layer profile at steady-state is consistent with CO being mainly produced at the surface by heterogeneous reactions followed by a rapid homogeneous combustion in the boundary layer towards buoyancy.

  17. Experimental and numerical investigation on cladding of corrosion-erosion resistant materials by a high power direct diode laser

    NASA Astrophysics Data System (ADS)

    Farahmand, Parisa

    advantages due to creating coating layers with superior properties in terms of purity, homogeneity, low dilution, hardness, bonding, and microstructure. In the development of modern materials for hardfacing applications, the functionality is often improved by combining materials with different properties into composites. Metal Matrix Composite (MMC) coating is a composite material with two constituent parts, i.e., matrix and the reinforcement. This class of composites are addressing improved mechanical properties such as stiffness, strength, toughness, and tribological and chemical resistance. Fabrication of MMCs is to achieve a combination of properties not achievable by any of the materials acting alone. MMCs have attracted significant attention for decades due to their combination of wear-resistivity, corrosion-resistivity, thermal, electrical and magnetic properties. Presently, there is a strong emphasis on the development of advanced functional coatings for corrosion, erosion, and wear protection for different industrial applications. In this research, a laser cladding system equipped with a high power direct diode laser associated with gas driven metal powder delivery system was used to develop advanced MMC coatings. The high power direct diode laser used in this study offers wider beam spot, shorter wavelength and uniform power distribution. These properties make the cladding set-up ideal for coating due to fewer cladding tracks, lower operation cost, higher laser absorption, and improved coating qualities. In order to prevent crack propagation, porosity, and uniform dispersion of carbides in MMC coating, cladding procedure was assisted by an induction heater as a second heat source. The developed defect free MMC coatings were combined with nano-size particles of WC, rare earth (RE) element (La2O3), and Mo as a refractory metal to enhance mechanical properties, chemical composition, and subsequently improve the tribological performance of the coatings. The resistance

  18. Investigation of Friction Stir Welding and Laser Engineered Net Shaping of Metal Matrix Composite Materials

    NASA Technical Reports Server (NTRS)

    Diwan, Ravinder M.

    2002-01-01

    prior set of operating conditions. Weld quality was evaluated using radiography and standard metallography techniques. Another aspect of the MMCs centered around the use of the laser engineered net shaping (LENS) processing of selected Narloy-Z composites. Such an approach has been earlier studied for fabrication of stainless steels. In the present study, attempts were made to fabricate straight cylindrical specimens using LENS process of Narloy-Z and Narloy-Z with 20 vol. % Al2O3 MMCs using the direct metal deposition Optomec LENS-750 system.

  19. Detection and quantification of metals in organic materials by laser-SNMS with nonresonant multiphoton ionization.

    PubMed

    Schnieders, A; Benninghoven, A

    2000-09-15

    We have shown that the sensitive detection and in favorable cases the quantification of metals in organic materials by laser-SNMS with nonresonant multiphoton ionization (NRMPI) is possible. As a model system, sputter-deposited submonolayer coverages of metals on polymer surfaces (polycarbonate, poly(vinylidene chloride), polyimide) were investigated. By use of these samples, relative sensitivity factors and detection limits of several metals (Be, Cr, Mn, Fe, Co, Ni, Mo, W) were determined using laser-SNMS with NRMPI. The relative sensitivity factors for this kind of sample show a high level of agreement with those for metals sputtered from alloys. The detection limits ( 1 ppm of a monolayer) are almost the same as for inorganic matrixes such as Si or GaAs. Laser-SNMS with NRMPI was also used for the determination of the elemental composition of the active centers of metalloproteins (namely, the purple acid phosphatases extracted from sweet potatoes and from red kidney beans). These results have shown the ability of laser-SNMS to detect metal atoms bound to organic macromolecules with an atom concentration as low as 1 ppm. In comparison to TOF-SIMS, laser-SNMS is more sensitive for metal detection in organic matrixes, since the secondary ion yields observed for these matrixes are reduced compared to matrixes optimized for high secondary ion emission, such as, for example, highly oxidized surfaces. PMID:11008762

  20. Measurement of ultrafast carrier recombination dynamics in mid-infrared semiconductor laser material

    NASA Astrophysics Data System (ADS)

    Cooley, William Theodore

    Shockley-Read-Hall, radiative, and Auger recombination rates in mid-infrared laser structures are measured and reported from time resolved photoluminescence (TRPL) using frequency upconversion. The mid-IR lasers studied were actual InAsSb/InAlAsSb multiple-quantum-well (MQW) diode lasers emitting near 3.3 μm which were previously characterized for laser performance. This effort extends the initial studies and reports on the carrier recombination dynamics. Shockley-Read-Hall, radiative and Auger recombination rates at low temperature (77 K) were measured and found to be ASRH/approx 10× 107 sec-1,/ Brad/approx 2× 10-10/ cm3sec-1 and CAuger < 10-29/ cm6s-1 respectively, for each sample measured. At higher temperatures (150 K), the recombination rates were measured to be ASRH/approx 40× 107sec-1,/ Brad/approx 0.78× 10- 10/ cm3/ sec-1 and CAuger < 7.0 × 10-28/ cm6s-1 respectively. The Auger coefficients reported here are significantly lower than previous reports on similar material from both theoretical and experimental investigations. This has significant implications for mid-IR laser research, in that Auger may not be the limiting problem.

  1. Detection and quantification of metals in organic materials by laser-SNMS with nonresonant multiphoton ionization.

    PubMed

    Schnieders, A; Benninghoven, A

    2000-09-15

    We have shown that the sensitive detection and in favorable cases the quantification of metals in organic materials by laser-SNMS with nonresonant multiphoton ionization (NRMPI) is possible. As a model system, sputter-deposited submonolayer coverages of metals on polymer surfaces (polycarbonate, poly(vinylidene chloride), polyimide) were investigated. By use of these samples, relative sensitivity factors and detection limits of several metals (Be, Cr, Mn, Fe, Co, Ni, Mo, W) were determined using laser-SNMS with NRMPI. The relative sensitivity factors for this kind of sample show a high level of agreement with those for metals sputtered from alloys. The detection limits ( 1 ppm of a monolayer) are almost the same as for inorganic matrixes such as Si or GaAs. Laser-SNMS with NRMPI was also used for the determination of the elemental composition of the active centers of metalloproteins (namely, the purple acid phosphatases extracted from sweet potatoes and from red kidney beans). These results have shown the ability of laser-SNMS to detect metal atoms bound to organic macromolecules with an atom concentration as low as 1 ppm. In comparison to TOF-SIMS, laser-SNMS is more sensitive for metal detection in organic matrixes, since the secondary ion yields observed for these matrixes are reduced compared to matrixes optimized for high secondary ion emission, such as, for example, highly oxidized surfaces.

  2. Low-order harmonic generation in nanosecond laser ablation plasmas of carbon containing materials

    NASA Astrophysics Data System (ADS)

    Lopez-Quintas, I.; Oujja, M.; Sanz, M.; Martín, M.; Ganeev, R. A.; Castillejo, M.

    2013-08-01

    In this work we report on a systematic study of the spatiotemporal behaviour of low-order harmonics generated in nanosecond laser ablation plasmas of carbon containing materials. Plasmas were generated from targets of graphite and boron carbide ablated with a nanosecond Q-switched Nd:YAG laser at 1064 nm. Low-order harmonics (3rd and 5th) of the fundamental wavelength of a ns Nd:YAG driving laser, propagating perpendicularly to the ablation laser at variable time delays, were observed. The temporal study of the low-order harmonics generated under vacuum and atmospheres of Kr and Xe, revealed the presence of two populations that contribute to the harmonic generation (HG) at different times. It was found that under vacuum only small species contribute to the HG process, whereas under buffer gas, heavier species, such as clusters and nanoparticles, contribute to the HG at longer times. Optical emission spectroscopy, time of flight mass spectrometry and characterization of deposits collected on-line on a nearby substrate provided additional information that complemented the results of the spatiotemporal study of the generated harmonics. This approach to ablation plume analysis allows elucidating the identity of the nonlinear emitters in laser ablation plasmas and facilitates the investigation of efficient, nanoparticle-enhanced, coherent short wavelength generation processes.

  3. Laser material micro-working (LMμW): some new surface processes

    NASA Astrophysics Data System (ADS)

    Daurelio, G.; D'Alonzo, M.

    2007-05-01

    On the last recent years many new Laser Surface Processes have been studied and tested in the field of the L.M. μW. - Laser Material Micro Working. Still today many of these "young" processes are to study and more and more searches are dedicated to they. These are the Marking, Texturing, Fine Texturing, Filling, Polishing, Micro Shot-Penning, Silking and Colouring. This experimental work reports the results obtained in the field of the Laser Surface Fine Texturing on AISI 304 and 430 Stainless Steels by using a Marking System, that is a Nd:YAG Laser, VECTORMARK type by TRUMPH ( D ). So some new laser surface finishes, called by Authors, - Effetto tessuto, con trama e ordito (Woven effect, with weft and warp) - Effetto pelle scamosciata ( Effect shammy leather ) - Effetto pelle uncinata ( Effect hooked skin ) - Effetto pelle unghiata ( Effect skin looking like scratch ) - Effetto pelle damascata ( Effect damask skin ) - Effetto speculare , ottonato ( Specular effect, looking like brass ) Effetto speculare, bronzato ( specular effect looking like bronze ) - Effetto speculare, argenteo ( specular, looking like silver effect ) - Effetto speculare, ramato ( Specular effect, looking like copper ), Effetto Speculare, dorato ( Specular effect, looking like gold ) - Effetto speculare , dorato, a raggiera ( Specular effect, looking like gold, to aureole) , were carried out. The work is still in progress.

  4. Reactive oxygen species production in single cells following laser irradiation (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Duquette, Michelle L.; Kim, Justine; Shi, Linda Z.; Berns, Michael W.

    2015-08-01

    Region specific DNA breaks can be created in single cells using laser light that damages DNA but does not directly generate reactive oxygen species (ROS). We have examined the cellular response to directly generated DNA breaks in single cells. Using a combination of ROS specific dyes and oxidase inhibitors we have found that the oxidase and chromatin remodeling protein Lysine demethylase I (LSD1) generates detectable ROS as a byproduct of its chromatin remodeling activity during the initial DNA damage response. ROS is produced at detectable amounts primarily within the first 3 minutes post irradiation. LSD1 activity has been previously associated with transcriptional regulation therefore these findings have implications for regulation of gene expression following DNA damage particularly in cells with altered redox states.

  5. Remote monostatic detection of radioactive material by laser-induced breakdown

    NASA Astrophysics Data System (ADS)

    Isaacs, Joshua; Miao, Chenlong; Sprangle, Phillip

    2016-03-01

    This paper analyzes and evaluates a concept for remotely detecting the presence of radioactivity using electromagnetic signatures. The detection concept is based on the use of laser beams and the resulting electromagnetic signatures near the radioactive material. Free electrons, generated from ionizing radiation associated with the radioactive material, cascade down to low energies and attach to molecular oxygen. The resulting ion density depends on the level of radioactivity and can be readily photo-ionized by a low-intensity laser beam. This process provides a controllable source of seed electrons for the further collisional ionization (breakdown) of the air using a high-power, focused, CO2 laser pulse. When the air breakdown process saturates, the ionizing CO2 radiation reflects off the plasma region and can be detected. The time required for this to occur is a function of the level of radioactivity. This monostatic detection arrangement has the advantage that both the photo-ionizing and avalanche laser beams and the detector can be co-located.

  6. Development of Novel Composite and Random Materials for Nonlinear Optics and Lasers

    NASA Technical Reports Server (NTRS)

    Noginov, Mikhail

    2002-01-01

    A qualitative model explaining sharp spectral peaks in emission of solid-state random laser materials with broad-band gain is proposed. The suggested mechanism of coherent emission relies on synchronization of phases in an ensemble of emitting centers, via time delays provided by a network of random scatterers, and amplification of spontaneous emission that supports the spontaneously organized coherent state. Laser-like emission from powders of solid-state luminophosphors, characterized by dramatic narrowing of the emission spectrum and shortening of emission pulses above the threshold, was first observed by Markushev et al. and further studied by a number of research groups. In particular, it has been shown that when the pumping energy significantly exceeds the threshold, one or several narrow emission lines can be observed in broad-band gain media with scatterers, such as films of ZnO nanoparticles, films of pi-conjugated polymers or infiltrated opals. The experimental features, commonly observed in various solid-state random laser materials characterized by different particle sizes, different values of the photon mean free path l*, different indexes of refraction, etc.. can be described as follows. (Liquid dye random lasers are not discussed here.)

  7. Intravascular laser speckle imaging for the mechanical analysis of coronary plaques (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Hosoda, Masaki; Wang, Jing; Tsikudi, Diane; Nadkarni, Seemantini

    2016-02-01

    Acute myocardial infarction is frequently caused by the rupture of coronary plaques with severely compromised viscoelastic properties. We have developed a new optical technology termed intravascular laser speckle imaging (ILSI) that evaluates plaque viscoelastic properties, by measuring the time scale (time constant, τ) of temporally evolving laser speckle fluctuations. To enable coronary evaluation in vivo, an optical ILSI catheter has been developed that accomplishes omni-directional illumination and viewing of the entire coronary circumference without the need for mechanical rotation. Here, we describe the capability of ILSI for evaluating human coronary atherosclerosis in cadaveric hearts. ILSI was conducted in conjunction with optical coherence tomography (OCT) imaging in five human cadaveric hearts. The left coronary artery (LCA), left anterior descending (LAD), left circumflex artery (LCx), and right coronary artery (RCA) segments were resected and secured on custom-developed coronary holders to enable accurate co-registration between ILSI, OCT, and histopathology. Speckle time constants, τ, calculated from each ILSI section were compared with lipid and collagen content measured from quantitative Histopathological analysis of the corresponding Oil Red O and Picrosirius Red stained sections. Because the presence of low viscosity lipid elicits rapid speckle fluctuations, we observed an inverse correlation between τ measured by ILSI and lipid content (R= -0.64, p< 0.05). In contrast, the higher viscoelastic modulus of fibrous regions resulted in a positive correlation between τ and collagen content (R= 0.54, p< 0.05). These results demonstrate the feasibility of conducting ILSI evaluation of arterial mechanical properties using a miniaturized omni-directional catheter.

  8. Present and future status of flexible spectral imaging color enhancement and blue laser imaging technology.

    PubMed

    Osawa, Hiroyuki; Yamamoto, Hironori

    2014-01-01

    The usefulness of flexible spectral imaging color enhancement (FICE) has been reported for evaluating the esophagus, stomach, and small and large intestine. Higher contrast is shown between cancer and the surrounding mucosa in the esophagus and stomach and may facilitate the detection of gastric cancers missed by white light imaging alone. The surface patterns of gastric mucosa are clearly visualized in non-malignant areas but are irregular and blurred in malignant areas, leading to clear demarcation. Capsule endoscopy with FICE detects angiodysplasia and erosions of the small intestine. The surface and vascular pattern with FICE is useful for the differential diagnosis of colorectal polyps. However, FICE remains somewhat poor at visualizing mucosal microvasculature on a tumor surface. Narrow-band imaging (NBI) is dark in observing whole gastric mucosa and poor at visualizing mucosal microstructure. Blue laser imaging (BLI) has the potential to resolve these limitations. Narrow-band laser light combined with white light shows irregular microvessels on both differentiated and undifferentiated gastric cancer similar to those using NBI. In addition, irregular surface patterns including minute white zones are clearly seen on the uneven surface of differentiated lesions, resulting in exclusion of undifferentiated lesions. Using both distant and close-up views, a high contrast between green intestinal metaplasia and brown gastric cancer may lead to early detection of gastric cancers and determination of a demarcation line. BLI produces high-contrast images in esophageal cancer with clear vision of intrapapillary capillary loops and also predicts the histopathological diagnosis and depth of invasion in colorectal neoplasms.

  9. A hierarchical view on material formation during pulsed-laser synthesis of nanoparticles in liquid.

    PubMed

    Ibrahimkutty, Shyjumon; Wagener, Philipp; dos Santos Rolo, Tomy; Karpov, Dmitry; Menzel, Andreas; Baumbach, Tilo; Barcikowski, Stephan; Plech, Anton

    2015-01-01

    Pulsed-laser assisted nanoparticle synthesis in liquids (PLAL) is a versatile tool for nanoparticle synthesis. However, fundamental aspects of structure formation during PLAL are presently poorly understood. We analyse the spatio-temporal kinetics during PLAL by means of fast X-ray radiography (XR) and scanning small-angle X-ray scattering (SAXS), which permits us to probe the process on length scales from nanometers to millimeters with microsecond temporal resolution. We find that the global structural evolution, such as the dynamics of the vapor bubble can be correlated to the locus and evolution of silver nanoparticles. The bubble plays an important role in particle formation, as it confines the primary particles and redeposits them to the substrate. Agglomeration takes place for the confined particles in the second bubble. Additionally, upon the collapse of the second bubble a jet of confined material is ejected perpendicularly to the surface. We hypothesize that these kinetics influence the final particle size distribution and determine the quality of the resulting colloids, such as polydispersity and modality through the interplay between particle cloud compression and particle release into the liquid. PMID:26549694

  10. Identification of pavement material properties using a scanning laser Doppler vibrometer

    NASA Astrophysics Data System (ADS)

    Hasheminejad, Navid; Vuye, Cedric; Van den Bergh, Wim; Dirckx, Joris; Leysen, Jari; Sels, Seppe; Vanlanduit, Steve

    2016-06-01

    This paper presents an inverse modeling approach to estimate mechanical properties of asphalt concrete (i.e. Young's modulus E, Poisson ratio ν and damping coefficients). Modal analysis was performed on an asphalt slab using a shaker to excite the specimen and an optical measurement system (a Scanning Laser Doppler Vibrometer or SLDV) to measure the velocity of a measurement grid on the surface of the slab. The SLDV has the ability to measure the vibration pattern of an object with high accuracy, short testing time and without making any contact. The measured data were used as inputs for a frequency domain model parameter estimation method (the Polymax estimator). Meanwhile, natural frequencies and damping ratios of the system were calculated using a Finite Element Modeling (FEM) method. Then, the Modal Assurance Criterion (MAC) was used to pair the mode shapes of the structure determined by measurements and estimated by FEM. By changing the inputs of the FEM analysis (E, ν and damping coefficients of the material) iteratively and minimizing the discrepancy between paired natural frequencies and damping ratios of the system estimated using the Polymax estimator and calculated by FEM, the Young's modulus, Poisson ratio and damping coefficients of the asphalt slab were estimated.

  11. Analysis of continuum generation in bulk materials with a femtosecond Ti:Sapph laser

    NASA Astrophysics Data System (ADS)

    Bowman Pilkington, Sherrie; Roberson, Stephen D.; Pellegrino, Paul M.

    2016-05-01

    There is a significant need for the generation of highly stable continuum beams for a wide variety of optical diagnostic techniques. Of particular interest to this group are those techniques being used for chemical detection, such as Multiplex Coherent Anti-Stokes Raman Scattering (MCARS), stimulated Raman scattering, two-photon absorption spectroscopy, and techniques involving ultrafast optical parametric amplifiers (OPAs). While photonic crystal fibers (PCFs) are popular and provide an ample method for continuum generation under very specific conditions, they are not particularly stable in unfavorable conditions and can exhibit energy fluctuations and lack of coherence. Bulk solid materials, commonly sapphire or YAG crystals, can provide incredibly broad and smooth spectra with better temporal and spatial coherence. In this study, we present an in-depth analysis of femtosecond continuum generation in sapphire and YAG crystals using a 40fs Ti:Sapphire laser. Beam size, pump pulse energy, beam profile, and a variety of focusing conditions are considered. In addition, an analysis of the thick lens theory required for collimation of the continuum beam has been conducted and experimentally verified.

  12. A hierarchical view on material formation during pulsed-laser synthesis of nanoparticles in liquid

    PubMed Central

    Ibrahimkutty, Shyjumon; Wagener, Philipp; Rolo, Tomy dos Santos; Karpov, Dmitry; Menzel, Andreas; Baumbach, Tilo; Barcikowski, Stephan; Plech, Anton

    2015-01-01

    Pulsed-laser assisted nanoparticle synthesis in liquids (PLAL) is a versatile tool for nanoparticle synthesis. However, fundamental aspects of structure formation during PLAL are presently poorly understood. We analyse the spatio-temporal kinetics during PLAL by means of fast X-ray radiography (XR) and scanning small-angle X-ray scattering (SAXS), which permits us to probe the process on length scales from nanometers to millimeters with microsecond temporal resolution. We find that the global structural evolution, such as the dynamics of the vapor bubble can be correlated to the locus and evolution of silver nanoparticles. The bubble plays an important role in particle formation, as it confines the primary particles and redeposits them to the substrate. Agglomeration takes place for the confined particles in the second bubble. Additionally, upon the collapse of the second bubble a jet of confined material is ejected perpendicularly to the surface. We hypothesize that these kinetics influence the final particle size distribution and determine the quality of the resulting colloids, such as polydispersity and modality through the interplay between particle cloud compression and particle release into the liquid. PMID:26549694

  13. Coupled photo-thermal and time resolved reflectivity methods to original investigation of laser/material nanosecond interaction

    NASA Astrophysics Data System (ADS)

    Semmar, N.; Martan, J.; Cibulka, O.; Le Menn, E.; Boulmer-Leborgne, C.

    2006-05-01

    A high number of papers were published on the simulation of laser/surface interaction at the level of nanosecond scale. Several assumptions on thermal properties data, laser spot homogeneity, were assumed for describing as well as possible the boundary conditions, the mathematical writing and finally the numerical or the analytical results. A few tentative of surface temperature monitoring during laser processing were proposed for the numerical validation. Also, simulation of the melting kinetics is rarely directly compared to in situ experiments. It is very hard to determine the time duration of a melting pool by in situ experiments. It should be the same for the surface temperature. A new method to plot the thermal history of the surface by using a combination of the Time Resolved Reflectivity (TRR) and the Pulsed Photo-Thermal (PPT) or Infrared Radiometry (IR) methods is proposed in this paper. Surface temperature, melting kinetics, threshold of melting and threshold of plasma formation are determined in the case of KrF laser spot in interaction with several materials. In the first step, the experimental setup including fast detectors (IR, UV, Vis.) and related optical devices is described. In the second step, typical results (TRR and IR spectra) for monocrystaline silicon are presented and discussed. Namely, phase change transitions (melting and resolidification) are detected versus fluence change and number of laser shots change. TRR and IR spectra of metallic surfaces (Cu, Mo, Ni, Stainless steel 15330 and 17246, Sn, Ti), are measured. For each sample the surface temperature during heating, the threshold of melting, melting duration and the threshold of plasma formation are directly deduced.

  14. In situ XFEL measurement system for Earth and planetary materials under laser-induced ultrahigh-pressure conditions

    NASA Astrophysics Data System (ADS)

    Tange, Y.; Ozaki, N.; Matsuoka, T.; Ogawa, T.; Albertazzi, B.; Habara, H.; Takahashi, K.; Matsuyama, S.; Yamauchi, K.; Tanaka, K.; Kodama, R.; Sato, T.; Sekine, T.; Seto, Y.; Okuchi, T.; Yabuuchi, T.; Inubushi, Y.; Yabashi, M.

    2015-12-01

    High-pressure and high-temperature in situ experiments have revealed behaviors of the earth and planetary constituents under extreme conditions, and contribute to progress our understandings about physical and chemical structure of planetary interiors. These in situ techniques have developed with the third-generation synchrotron radiation facilities such as APS, ESRF, and SPring-8 mainly using large volume presses and diamond anvil cells. In addition to the synchrotron light source, recently X-ray free electron laser (XFEL) facilities have been developed as LCLS and SACLA. The brilliant and extremely short-pulsed XFELs make it possible to carry out femto-second time-resolve measurements, and to observe materials under dynamic/shock compression clearly. Techniques using high-power laser and XFEL are expected to be a next-generation experimental platform, and a pump-probe measurement system using high-power lasers and XFEL was installed at BL3EH5 in SPring-8/SACLA interoperable experimental facility. The system is composed of 45 TW laser, 2-dimentional <μm X-ray focusing system (KB mirrors), vacuumed sample chamber, and the MPCCD detector developed for the 10-fs ultra-short pulsed XFEL light source. The high-power laser enables us to generate up to 100 GPa for metal, simple oxide, and natural/synthesized mineral samples. Samples are mounted on sample holders and aligned at the center of the vacuum chamber using a 4-axis Goniometer head. In this presentation, we will overview the experimental setups and typical results of current pump-probe system using XFEL in SACLA.

  15. A contribution to the development of wide band-gap nonlinear optical laser materials

    NASA Astrophysics Data System (ADS)

    Stone-Sundberg, Jennifer Leigh

    The primary focus of this work is on examining structure-property relationships of interest for high-power nonlinear optical and laser crystals. An intuitive and simply illustrated method for assessing the nonlinear optical potential of structurally characterized noncentrosymmetric materials is introduced. This method is applied to materials including common quartz and tourmaline and then extended to synthetic materials including borates, silicates, aluminates, and phosphates. Particularly, the contributions of symmetric tetrahedral and triangular anionic groups are inspected. It is shown that both types of groups significantly contribute to the optical frequency converting abilities of noncentrosymmetric crystals. In this study, several known materials are included as well as several new materials. The roles of the orientation, composition, and packing density of these anionic groups are also discussed. The structures and optical properties of the known materials BPO 4, NaAlO2, LaCa4O(BO3)3, and tourmaline; the new compounds La0.8Y0.2Sc3 (BO3)4 and Ba2B10O 17; and the laser host Sr3Y0.75Yb0.25(BO 3)3 are described.

  16. Contribution of material's surface layer on charge state distribution in laser ablation plasma.

    PubMed

    Kumaki, Masafumi; Steski, Dannie; Ikeda, Shunsuke; Kanesue, Takeshi; Okamura, Masahiro; Washio, Masakazu

    2016-02-01

    To generate laser ablation plasma, a pulse laser is focused onto a solid target making a crater on the surface. However, not all the evaporated material is efficiently converted to hot plasma. Some portion of the evaporated material could be turned to low temperature plasma or just vapor. To investigate the mechanism, we prepared an aluminum target coated by thin carbon layers. Then, we measured the ablation plasma properties with different carbon thicknesses on the aluminum plate. The results showed that C(6+) ions were generated only from the surface layer. The deep layers (over 250 nm from the surface) did not provide high charge state ions. On the other hand, low charge state ions were mainly produced by the deeper layers of the target. Atoms deeper than 1000 nm did not contribute to the ablation plasma formation. PMID:26931982

  17. Material Property Measurement of Metallic Parts using the INEEL Laser Ultrasonic Camera

    SciTech Connect

    Telschow, Kenneth Louis; Deason, Vance Albert; Schley, Robert Scott; Watson, Scott Marshall

    1999-08-01

    Ultrasonic waves form a useful nondestructive evaluation (NDE) probe for determining physical, microstructural, and mechanical properties of materials and parts. Noncontacting laser ultrasonic methods are desired for remote measurements and on-line manufacture process monitoring. Researchers at the Idaho National Engineering & Environmental Laboratory (INEEL) have developed a versatile new method for detection of ultrasonic motion at surfaces. This method directly images, without the need for scanning, the surface distribution of subnanometer ultrasonic motion. By eliminating the need for scanning over large areas or complex parts, the inspection process can be greatly speeded up. Examples include measurements on parts with complex geometries through resonant ultrasound spectroscopy and of the properties of sheet materials determined through anisotropic elastic Lamb wave propagation. The operation and capabilities of the INEEL Laser Ultrasonic Camera are described along with measurement results.

  18. PMMA microstructure as KrF excimer-laser LIGA material

    NASA Astrophysics Data System (ADS)

    Yang, Chii-Rong; Chou, Bruce C. S.; Chou, Hsiao-Yu; Lin, Frank H. S.; Kuo, Wen-Kai; Luo, Roger G. S.; Chang, Jer-Wei; Wei, Z. J.

    1998-08-01

    PMMA (polymethyl methacrylate) has been widely used as x-ray LIGA material for its good features of electrical acid plating of all common metals to industrial applications. Unlike the tough characteristics of polyimide in almost all alkaline and acid solutions, PMMA is easily removed in chemical etchants after electroplating process. For this reason, ablation- etching characteristics of PMMA material for 3D microstructures fabrication using a 248 nm KrF excimer laser were investigated. Moreover, the uses of the laminated dry film were also studied in this work. Experimental results show that PMMA microstructures can produce the near-vertical side- wall profile as the laser fluence up to 2.5 J/cm2. PMMA templates with high aspect ratio of around 25 were demonstrated, and the sequential electroplating processes have realized the metallic microstructures. Moreover, the microstructures fabricated in dry film show the perfect side- wall quality, and no residues of debris were found.

  19. Laser-induced deposition of nanostructured copper microwires on surfaces of composite materials

    NASA Astrophysics Data System (ADS)

    Tumkin, Ilia I.; Panov, Maxim S.; Shishkova, Ekaterina V.; Bal'makov, Michail D.

    2015-05-01

    Microelectronics industry is growing fast and the rate of new devices' development increases every year. Therefore, methods for simple and high-precision metal coating on dielectrics are needed. Existing methods do not allow performing the high-precision metal deposition without using photomasks, while making photomask for each prototype is long and expensive process. One of the methods of maskless metal deposition is laser-induced chemical liquid-phase deposition (LCLD). In this work we show the effect of substrate surface type on a result of LCLD. Deposited copper structures were characterized by SEM, EDX and impedance spectroscopy. The results show that laser-induced copper deposition is highly affected by the surface being homogeneous or composite material. It was found that the deposits with low resistivity and high quality metal localization mostly appear on the two-phase surfaces. In contrast, deposits on one-phase surfaces exhibited poor topology of copper material.

  20. Contribution of material's surface layer on charge state distribution in laser ablation plasma

    NASA Astrophysics Data System (ADS)

    Kumaki, Masafumi; Steski, Dannie; Ikeda, Shunsuke; Kanesue, Takeshi; Okamura, Masahiro; Washio, Masakazu

    2016-02-01

    To generate laser ablation plasma, a pulse laser is focused onto a solid target making a crater on the surface. However, not all the evaporated material is efficiently converted to hot plasma. Some portion of the evaporated material could be turned to low temperature plasma or just vapor. To investigate the mechanism, we prepared an aluminum target coated by thin carbon layers. Then, we measured the ablation plasma properties with different carbon thicknesses on the aluminum plate. The results showed that C6+ ions were generated only from the surface layer. The deep layers (over 250 nm from the surface) did not provide high charge state ions. On the other hand, low charge state ions were mainly produced by the deeper layers of the target. Atoms deeper than 1000 nm did not contribute to the ablation plasma formation.