Science.gov

Sample records for melt-extracted amorphous yag

  1. Diameter Dependence of Giant Magneto-Impedance Effect in Co-BASED Melt Extracted Amorphous Wires

    NASA Astrophysics Data System (ADS)

    Zhang, Shuling; Xing, Dawei; Sun, Jianfei

    2011-06-01

    Naked Co68.25Fe4.5Si12.25B15 amorphous wires of 67μm, 56μm, 52μm, 47μm and 31μm in diameter are produced by melt extraction method. Their giant magneto impedance (GMI) effect is investigated at frequencies from 0.1MHz to13MHz. Significant diameter dependence of GMI effect is studied. Thicker wires exhibit strong GMI effect and have clear characteristic frequencies at which their impedance ratio ΔZ/Z are largest. Largest impedance response is obtained in 67μm wires with the ΔZ/Z of 442% and field sensitivity of 71.5%/Oe. Wires of 31μm in diameter show increasing ΔZ/Z as frequency and have a steady field sensitivity of 30.7-33.6%/Oe in a wide frequency range from 3MHz to 13MHz. The different frequency dependence of GMI effect is discussed in the light of the skin effect. These amorphous wires are suitable for applications in high performance field sensors and can fit different demand.

  2. Study on feasibility of producing an amorphous surface layer of Fe49Cr18Mo7B16C4Nb3 by pulsed Nd:YAG laser surface melting

    NASA Astrophysics Data System (ADS)

    Mojaver, Reza; Mojtahedi, Faezeh; Shahverdi, Hamid Reza; Torkamany, Mohammad Javad

    2013-01-01

    This work aims to investigate whether an amorphous surface layer can be obtained when as-cast Fe49Cr18Mo7B16C4Nb3 alloy is submitted to pulsed Nd:YAG laser surface melting. The experiments were conducted in the various laser scanning speeds. The microstructures of laser treated zones were investigated by X-ray diffraction XRD and Field Emission Scanning Electron Microscope (FESEM) and their microhardness were measured, too. The chemical composition of different points of each sample was analyzed by energy-dispersive X-ray spectroscopy EDS. Although the estimated cooling rates in surface layers were higher than the required cooling rate to achieve full amorphization, but the present experiments were unable to retain complete glassy microstructure on surface and a mixture of amorphous (low volume fraction) and ultrafine grained phases were produced in surface of samples. Based on the findings, it was understood that the overlapping of successive pulses and element redistributions occurred in pulsed laser melting could severely restrict amorphization. The influence of laser scan speed and laser power on heat input, melting ratio, compositional changes and cracking in laser treated zone were discussed separately. It is suggested that the limited range of laser variables in pulsed Nd:YAG laser melting may help to produce a sound amorphous phase of as-cast Fe49Cr18Mo7B16C4Nb3 alloy.

  3. Efficiency of melt extraction from partially molten regions

    NASA Astrophysics Data System (ADS)

    Hier-Majumder, S.; Abbott, M. E.; Drombosky, T.; Wimert, J. T.

    2011-12-01

    We discuss the efficiency of buoyancy-driven melt extraction in relation to the low velocity layer (LVL), atop the transition zone, and the ultralow velocity zones (ULVZ), atop the core mantle boundary. The LVL is characterized by a relatively large thickness, globally varying on the order of 30-90 km. It is inferred that the LVL is characterized by a modest amount of melting, 1% or less. The ULVZ, in contrast, is much thinner, with an average thickness of 10 km. It is also characterized by a density between 8-10% higher than the surrounding mantle, and contains up to 10% by volume melt. Three factors, frictional resistance, capillary tension, and stirring can contribute to long term melt retention in these partially molten regions. Frictional resistance to melt percolation is inversely proportional to the melt fraction squared. Consequently, the drainage efficiency of both buoyant and dense melts are reduced at low melt fractions. Strong tension on grain boundaries reduces the dihedral angle at the melt-grain triple junctions, establishing a well-connected network. Despite the presence of this well connected pathway, a larger force is required to counter the strong capillary tension and segregate melt from the matrix, especially at small melt fractions. Finally, compaction within the ULVZ stirred by convective motions in the overlying mantle can also preclude substantial drainage of melt and retain the melt over geological times.

  4. Influence of direct bias current on the electromagnetic properties of melt-extracted microwires and their composites

    NASA Astrophysics Data System (ADS)

    Qin, F. X.; Tang, J.; Popov, V. V.; Liu, J. S.; Peng, H. X.; Brosseau, C.

    2014-01-01

    We study the influence of a direct bias current on the magnetoimpedance (MI) in melt-extracted amorphous CoFeSiB microwires and the effective electromagnetic properties of epoxy composites filled with these microwires. Our analysis reveals two remarkable features of the current dependence of MI in the range of gigahertz frequencies: a redshift of the dielectric resonance frequency and a decrease of the peak resonance of the effective permittivity as the bias current increases. Both effects are intrinsically linked to the influence of the polymer matrix on the magnetic structure and properties of the microwires. A discussion of these results is proposed in terms of two competing effects of the bias current, i.e., the induced additional effective field in the plane normal to the wire axis and the stress relief from Joule heating.

  5. Superelasticity of Cu-Ni-Al shape-memory fibers prepared by melt extraction technique

    NASA Astrophysics Data System (ADS)

    Li, Dong-yue; Zhang, Shu-ling; Liao, Wei-bing; Geng, Gui-hong; Zhang, Yong

    2016-08-01

    In the paper, a melt extraction method was used to fabricate Cu-4Ni-14Al (wt%) fiber materials with diameters between 50 and 200 μm. The fibers exhibited superelasticity and temperature-induced martensitic transformation. The microstructures and superelasticity behavior of the fibers were studied via scanning electron microscopy (SEM) and a dynamic mechanical analyzer (DMA), respectively. Appropriate heat treatment further improves the plasticity of Cu-based alloys. The serration behavior observed during the loading process is due to the multiple martensite phase transformation.

  6. Microstructural Characterization of Melt Extracted High-Nb-Containing TiAl-Based Fiber

    PubMed Central

    Zhang, Shuzhi; Zhang, Shuling; Chen, Yanfei; Han, Jianchao; Zhang, Changjiang; Wang, Xiaopeng; Chen, Yuyong

    2017-01-01

    The microstructure of melt extracted Ti-44Al-8Nb-0.2W-0.2B-1.5Si fiber were investigated. When the rotation speed increased from 2000 to 2600 r/min, the appearance of the wire was uniform with no Rayleigh-wave default. The structure was mainly composed of fine α2 (α) phase dendritic crystal and a second phase between dendrite arms and grain boundaries. The precipitated second phases were confirmed to be Ti5Si3 from the eutectic reaction L→Ti5Si3 + α and TiB. As the lower content of Si and higher cooling rate, a divorced eutectic microstructure was obtained. Segregation of Ti, Nb, B, Si, and Al occurred during rapid solidification. PMID:28772555

  7. Segment-Scale Melt Extraction at Mid-Ocean Ridges: A Play in Three Acts

    NASA Astrophysics Data System (ADS)

    Montesi, L. G.; Hebert, L. B.; Behn, M. D.

    2011-12-01

    At mid-ocean ridges, the lithosphere is created through a combination of melt extraction, metasomatism, and cooling, and the oceanic crust forms as melt collects near the surface. As the presence of melt also has rheological and geochemical consequences, a better understanding of the mechanisms that control melt migration and extraction at mid-ocean ridges is necessary to constrain the processes that form oceanic lithosphere and plate boundaries. Melt migration is described rigorously by two-phase transport equations in porous or fractured media. However, scaling considerations and geological constraints typically lead to certain simplifications when incorporated into geodynamical models. It is possible to capture the essence of melt migration and extraction by considering three principal stages: Stage 1. Vertical migration: Melt is generated by adiabatic decompression and rises nearly vertically from the zone of melt production to a melt-impermeable boundary, or permeability barrier, at the base of the thermal lithosphere. Stage 2. Focusing: Melt travels along a permeability barrier. The barrier is associated with a crystallization front and is slightly inclined toward the ridge axis following the thermal structure of the plate. At this stage melt focusing occurs toward and along the strike of the ridge. Stage 3. Extraction: Melt enters a melt extraction zone (MEZ) and is extracted to the surface. The MEZ represents the combined effect of faults and/or dikes that promote rapid lateral and vertical melt migration and eventual eruption on the seafloor. Stage 1 is expected based on scaling arguments of buoyancy and permeability [e.g., Zhu et al., Science, 2011]. Stages 2 and 3 are directly influenced by the structure of the lithosphere, which is itself controlled by the segmentation of the ridge axis, spreading rate, and mantle potential temperature. Thus, it is possible to use along-strike variations in melt delivery in well-studied geological settings to constrain

  8. Numerical models of mantle lithosphere weakening, erosion and delamination induced by melt extraction and emplacement

    NASA Astrophysics Data System (ADS)

    Wallner, Herbert; Schmeling, Harro

    2016-09-01

    Continental rifting caused by extension and heating from below affects the lithosphere or cratons in various ways. Volcanism and melt intrusions often occur along with thinning, weakening and even breaking lithosphere. Although mechanical necking models of the lithosphere are often applied, the aspects of melting and the implications due to melt transport and emplacement at shallower depths are not well understood. A two-phase flow approach employing melt extraction and shallow emplacement associated with thermal weakening is developed and compared with observations. The results of this comparison indicate the importance of partial melts and an asthenospheric magma source for increasing the rising rate of the lithosphere-asthenosphere boundary during extension. Thermo-mechanical physics of visco-plastic flow is approximated using the Finite Difference method with Eulerian formulation in 2D. The conservation of mass, momentum and energy equations are solved for a multi-component (crust-mantle) and two-phase (melt-matrix) system. Rheology is temperature- and stress-dependent. In consideration of depletion and enrichment melting and solidification are controlled by a simplified linear binary solid solution model. Melt is extracted and emplaced in predefined depth regions (emplacement zones) in the lithospheric mantle and crust. The Compaction Boussinesq Approximation was applied; its validity was tested against the Full Compaction formulation and found fully satisfactory for the case of sublithospheric melting models. A simple model guided by the geodynamic situation of the Rwenzori region typically results in updoming asthenosphere with melt-assisted erosion of the lithosphere's base. Even with a conservative approach for a temperature anomaly melting alone doubles the lithospheric erosion rate in comparison with a model without melting. With melt extraction and intrusion lithospheric erosion and upwelling of the lithosphere-asthenosphere boundary speeds up by a

  9. Spreading-rate dependence of melt extraction at mid-ocean ridges from mantle seismic refraction data.

    PubMed

    Lizarralde, Daniel; Gaherty, James B; Collins, John A; Hirth, Greg; Kim, Sangmyung D

    2004-12-09

    A variety of observations indicate that mid-ocean ridges produce less crust at spreading rates below 20 mm yr(-1) (refs 1-3), reflecting changes in fundamental ridge processes with decreasing spreading rate. The nature of these changes, however, remains uncertain, with end-member explanations being decreasing shallow melting or incomplete melt extraction, each due to the influence of a thicker thermal lid. Here we present results of a seismic refraction experiment designed to study mid-ocean ridge processes by imaging residual mantle structure. Our results reveal an abrupt lateral change in bulk mantle seismic properties associated with a change from slow to ultraslow palaeo-spreading rate. Changes in mantle velocity gradient, basement topography and crustal thickness all correlate with this spreading-rate change. These observations can be explained by variations in melt extraction at the ridge, with a gabbroic phase preferentially retained in the mantle at slower spreading rates. The estimated volume of retained melt balances the approximately 1.5-km difference in crustal thickness, suggesting that changes in spreading rate affect melt-extraction processes rather than total melting.

  10. Paradise Lost: Uncertainties in melting and melt extraction processes beneath oceanic spreading ridges

    NASA Astrophysics Data System (ADS)

    Kelemen, P. B.

    2014-12-01

    In many ways, decompression melting and focused melt transport beneath oceanic spreading ridges is the best understood igneous process on Earth. However, there are remaining - increasing - uncertainties in interpreting residual mantle peridotites. Indicators of degree of melting in residual peridotite are questionable. Yb concentration and spinel Cr# are affected by (a) small scale variations in reactive melt transport, (b) variable extents of melt extraction, and (c) "impregnation", i.e. partial crystallization of cooling melt in pore space. Roughly 75% of abyssal peridotites have undergone major element refertilization. Many may have undergone several melting events. The following three statements are inconsistent: (1) Peridotite melt productivity beyond cpx exhaustion is > 0.1%/GPa. (2) Crustal thickness is independent of spreading rate at rates > 2 cm/yr full rate (excluding ultra-slow spreading ridges). (3) Thermal models predict, and observations confirm, thick thermal boundary layers beneath slow spreading ridges. If (a) melt productivity is << 0.1%/GPa beyond cpx-out, and (b) cpx-out occurs > 15 km below the seafloor beneath most ridges, then the independence of crustal thickness with spreading rate can be understood. Most sampled peridotites from ridges melted beyond cpx-out. Cpx in these rocks formed via impregnation and/or exsolution during cooling. Most peridotites beneath ridges may undergo cpx exhaustion during decompression melting. This would entail an upward modification of potential temperature estimates. Alternatively, perhaps oceanic crustal thickness does vary with spreading rate but this is masked by complicated tectonics and serpentinization at slow-spreading ridges. Dissolution channels (dunites) are predicted to coalesce downstream, but numerical models of these have not shown why > 95% of oceanic crust forms in a zone < 5 km wide. There may be permeability barriers guiding deeper melt toward the ridge, but field studies have not identified

  11. Depths and Temperatures of Mantle Melt Extraction in the Southern Cascadia Subduction Zone (Invited)

    NASA Astrophysics Data System (ADS)

    Till, C.; Grove, T. L.; Donnelly-Nolan, J. M.; Carlson, R. W.

    2013-12-01

    Plagioclase and spinel lherzolite thermometry and barometry applied to an extensive suite of <10.5 Ma primitive basaltic lavas (most Mg#>0.70) containing variable H2O contents (<<1 to ~4 wt%) suggests these melts were extracted from the mantle at 40-58 km below Oregon's High Lava Plains, 41-51 km below California's Modoc Plateau, and 37-60 km below the central-southern Cascades volcanic arc. Of the 155 basalt samples investigated, 33 are calc-alkaline basalts (CAB) and the remainder are high alumina olivine tholeiites (HAOT) or mildly alkaline basalts (MAB). All 33 of the CAB are from the subduction-influenced volcanic centers of Lassen, Mt. Shasta, Three Sisters, Medicine Lake, and Newberry in the present-day Cascades arc or rear arc. All of these volcanic centers also erupted HAOT or MAB. Olivine-plagioclase hygrometry for a representative subset of the 20 CAB from Newberry indicates they contained ~4 wt% H2O prior to eruption. Water contents for the remaining CAB were approximated using the H2O-melt composition scaling relationship developed by Ruscitto et al. [2010, EPSL 298(1-2), 153-161] yielding ≤1-3 wt% H2O. The calculated pressures and temperatures of last equilibration with mantle lherzolite for all 33 CAB were adjusted for the effects of H2O following Till et al. [2012, JGR 117(B06206)] and are on average 50×15°C (1s) cooler and 1.65×0.27 km deeper than their calculated temperatures and depths for anhydrous conditions. The minimum depths of melt extraction calculated for all basalts considered (including the CAB) are close to the Moho, as determined by regional geophysical studies. Thus, our results suggest that the geophysical Moho and lithosphere-asthenosphere boundary are located in close proximity to one another (within 5-10 km). The basalts originated at 1185-1383°C and the presence of both wet and dry basalts that were generated at such different temperatures at similar times, depths, and geographic locations in the Cascades arc and rear arc

  12. Corrosion-resistant steel fiber produced by the melt-extraction method and its use in refractories

    NASA Astrophysics Data System (ADS)

    Van I-Kho; Ven-Nen, Lyu

    1992-09-01

    Corrosion-resistant steel fiber produced by the melt-extraction method has distinct reinforcing properties, a high capacity to bond with a refractory, low net-cost, and economic production. The introduction of corrosion-resistant steel fibers in refractory articles and materials for concrete spraying improves their thermal stability and mechanical strength. The service life of refractory articles is increased as a result of an increase in resistance to failure and impact loads. Use of corrosion-resistant steel fibers contributes to significant material energy savings, and improves the productivity of furnaces and apparatus.

  13. Lithological, Chemical and Chronological Constraints on Melt Extraction from the Mantle Section of the ~492 Ma Shetland Ophiolite Complex, Scotland

    NASA Astrophysics Data System (ADS)

    O'Driscoll, B.; Walker, R. J.; Clay, P. L.; Day, J. M.; Ash, R. D.; Daly, J. S.

    2015-12-01

    The mantle sections of ophiolites offer a means of studying the composition and structure of the oceanic mantle. In particular, the relations between different lithologies can be established in the field, permitting an assessment of the relative timing of processes such as melt extraction and melt-rock reaction. The Shetland Ophiolite Complex (SOC) contains a well-preserved mantle section that is dominated by harzburgite (≥70 vol.%), with dominantly chondritic present-day 187Os/188Os compositions1. Melt extraction and melt-rock reaction is evident in the form of dunite and chromitite layers and lenses, with thicknesses ranging from millimetres-to-metres. These lithologies are characteristic of supra-subduction zone processing and are considered to relate to closure of the Iapetus Ocean at ~492 Ma1. However, evidence of much earlier melt extraction has been suggested for some SOC harzburgites, which have relatively unradiogenic 187Os/188Os compositions that yield TRD model ages as old as ~1.4 Ga1. In order to assess the scales at which such compositional heterogeneities are preserved in the mantle, a small (45 m2) area of the SOC mantle section was selected for detailed lithological mapping and sampling. A selection of harzburgites (n=8), dunites (n=6) and pyroxenites (n=2) from this area has been analysed for their Os isotope and highly-siderophile element (HSE) compositions. Six of the harzburgites and four of the dunites have relative HSE abundances and gOs values that are approximately chondritic, with gOs ranging only from -0.6 to +2.7 (n=10). Two dunites have more radiogenic gOs (up to +7.5), that is correlated with enhanced concentrations of accessory base-metal sulphides, suggesting formation via melt percolation and melt-rock reaction. The two remaining harzburgites have less radiogenic gOs (-3.5 and -4), yielding Mesoproterozoic TRD ages. The new data indicate that a comparable range of Os isotope compositions to that previously measured across the

  14. [Raman spectra analysis of Nd : YAG single crystal and its nano-powder].

    PubMed

    Su, Jing; Zhang, Qing-Li; Yin, Shao-Tang; Sun, Dun-Lu; Shao, Shu-Fang

    2009-06-01

    In the present paper, the authors measured the Raman spectra of YAG/Nd : YAG single crystal, Nd : YAG precursor and the powder sintered at different temperatures. The bands of these Raman spectra were assigned and analyzed. The results show that there is a structure transformation process in the course of sintering Nd : YAG precursor. The powder sintered at 700 degrees C was amorphous and it is of AlO4 tetrahedron structure. With the increase in sintering temperatures, the Raman spectra varied mainly in two respects. One is the decrease in FWHM with the increase in the bands intensity; the other is the bands shift. These should be due to the increase in the order degree of the interface component. Additionally, the difference in the lattice vibration modes between the powders sintered at 800 degrees C and the Nd : YAG single crystal powder was caused by the contribution of the interface component.

  15. Relating surface roughness and magnetic domain structure to giant magneto-impedance of Co-rich melt-extracted microwires

    DOE PAGES

    Jiang, S. D.; Eggers, T.; Thiabgoh, O.; ...

    2017-04-11

    Understanding the relationship between the surface conditions and giant magneto-impedance (GMI) in Co-rich melt-extracted microwires is key to optimizing their magnetic responses for magnetic sensor applications. The surface magnetic domain structure (SMDS) parameters of ~45 μm diameter Co69.25Fe4.25Si13B13.5-xZrx (x = 0, 1, 2, 3) microwires, including the magnetic domain period (d) and surface roughness (Rq) as extracted from the magnetic force microscopy (MFM) images, have been correlated with GMI in the range 1–1000 MHz. It was found that substitution of B with 1 at. % Zr increased d of the base alloy from 729 to 740 nm while retaining Rqmore » from ~1 nm to ~3 nm. A tremendous impact on the GMI ratio was found, increasing the ratio from ~360% to ~490% at an operating frequency of 40 MHz. Further substitution with Zr decreased the high frequency GMI ratio, which can be understood by the significant increase in surface roughness evident by force microscopy. Lastly, this study demonstrates the application of the domain period and surface roughness found by force microscopy to the interpretation of the GMI in Co-rich microwires.« less

  16. Relating surface roughness and magnetic domain structure to giant magneto-impedance of Co-rich melt-extracted microwires

    PubMed Central

    Jiang, S. D.; Eggers, T.; Thiabgoh, O.; Xing, D. W.; Fei, W. D.; Shen, H. X.; Liu, J. S.; Zhang, J. R.; Fang, W. B.; Sun, J. F.; Srikanth, H.; Phan, M. H.

    2017-01-01

    Understanding the relationship between the surface conditions and giant magneto-impedance (GMI) in Co-rich melt-extracted microwires is key to optimizing their magnetic responses for magnetic sensor applications. The surface magnetic domain structure (SMDS) parameters of ~45 μm diameter Co69.25Fe4.25Si13B13.5-xZrx (x = 0, 1, 2, 3) microwires, including the magnetic domain period (d) and surface roughness (Rq) as extracted from the magnetic force microscopy (MFM) images, have been correlated with GMI in the range 1–1000 MHz. It was found that substitution of B with 1 at. % Zr increased d of the base alloy from 729 to 740 nm while retaining Rq from ~1 nm to ~3 nm. A tremendous impact on the GMI ratio was found, increasing the ratio from ~360% to ~490% at an operating frequency of 40 MHz. Further substitution with Zr decreased the high frequency GMI ratio, which can be understood by the significant increase in surface roughness evident by force microscopy. This study demonstrates the application of the domain period and surface roughness found by force microscopy to the interpretation of the GMI in Co-rich microwires. PMID:28397832

  17. Melt extraction in mush zones: The case of crystal-rich enclaves at the Sabatini Volcanic District (central Italy)

    NASA Astrophysics Data System (ADS)

    Masotta, M.; Mollo, S.; Gaeta, M.; Freda, C.

    2016-04-01

    A peculiar feature of the Sabatini Volcanic District (SVD, central Italy) is the occurrence of crystal-poor pumices and crystal-rich enclaves within the same eruptive host-deposit. The stratigraphic sequence of pumices and enclaves indicates the tapping of a stratified magma chamber, where a crystal-poor phonolitic magma lay on top of a more primitive crystal-rich magma. The crystal-rich enclaves are genetically related to the pumices and record the evolution of a solidification front, in which a more differentiated melt was produced, extracted and eventually erupted. We collected and analyzed crystal-rich enclaves from one of the largest phonolitic eruptions at the SVD and used their petrological and geochemical features to reconstruct magma differentiation and crystal-melt separation in the solidification front. On this basis, three groups of enclaves have been identified: porphyritic enclaves, holocrystalline enclaves and sanidinites. The mineralogical variability faithfully reproduces the spatial and temporal evolution expected of a solidification front, from early-to-intermediate crystallization conditions (porphyritic and holocrystalline type) to the late stage of solidification (sanidinites), in which the percolation of a more differentiated melt through the crystal mush triggered the instability of the solidification front. Results from numerical models indicate that gravitational instability is the most efficient mechanism to explain melt extraction in mush zones of medium-sized (~ 10 km3), short-lived (~ 104 years) magma chambers.

  18. Holosteric Nd : YAG lasers

    NASA Astrophysics Data System (ADS)

    Norrie, Callum

    A miniature Nd:YAG laser that was transversely pumped by a quasi-cw laser-diode array has been designed and constructed. This laser was injection seeded by a continuous wave single-frequency Nd:YAG laser that was also pumped by a laser- diode array. This was the first reported holosteric, or all-solid-state, laser that was capable of generating single frequency pulses in a high quality single transverse mode beam which it achieved at peak powers up to 7 kW. Two different types of laser-diode array were used in this work, and both have been characterised with respect to their use as pump sources for solid-state lasers. A fibre-coupled type SDL-2430-H2 laser-diode array, which emitted 100 mW from the end of a 100 mum core diameter fibre at the Nd:YAG absorption wavelength of 809 nm, was used to longitudinally pump a continuous wave Nd:YAG laser. Spatial hole-burning encouraged this laser to operate on several longitudinal modes, with an output power of up to 31 mW. With the addition of an etalon and a Brewster angled plate to the cavity of this laser, single longiuidinal mode operation was achieved at an output power level of 10 mW. The frequency from this laser was stabilised against thermal drift by phase sensitive locking to the resonance of an external reference cavity. The pump source for the transversely pumped Nd:YAG laser was an SDL-922-J quasi-cw laser-diode bar, which emitted from its 1 cm wide aperture pulses of 200 mus duration with energies up to 5 mJ at reperition rates between 10 - 100 pps. The characteristics of this laser-bar that were measured include a frequency chirp of 5 nm through the pulse, which was found to have a significant effect on the pumping of the Nd:YAG medium. An analysis of the pump-rate distribution throughout the Nd:YAG laser-rod was undertaken with reference to the transverse mode structure of this laser. This was used as the basis of a full rate-equation-based model of the transversely pumped laser. Fundamental transverse mode

  19. Zircon Record of the Plutonic-Volcanic Connection and Protracted Rhyolite Melt Extraction at Turkey Creek Caldera, Arizona

    NASA Astrophysics Data System (ADS)

    Deering, C. D.; Schoene, B.; Keller, C. B.; Bachmann, O.; Beane, R. J.; Ovtcharova, M.

    2014-12-01

    The Turkey Creek caldera of Southeastern Arizona formed as the result of the catastrophic eruption of more than 500 km3 of high-silica rhyolite (Rhyolite Canyon Tuff). This event occurred ~27 Ma and was coincident with the early phases of Basin and Range extension. The emplacement of the ignimbrite was immediately followed by a resurgent intrusion of dacite/monzonite porphyry (DPI), some of which reached the surface as crystal-rich dacite lavas (DPL) along the ring fault. Due to uplift and erosion, the intracaldera and outflow facies of the Rhyolite Canyon Tuff (RCT) and resurgent intrusion are well-exposed, which renders this an ideal laboratory for examining the plutonic-volcanic connection in a mid- to upper-crustal environment. We examined the potential petrogenetic link between the crystal-poor rhyolite and the crystal-rich intermediate intrusion and lavas through zircon CA-TIMS geochronology and ICP-MS trace element analyses. CA-TIMS U-Pb dates indicate that the RCT and DPI/DPL were coeval, forming over a protracted period of time (>300 kyrs.) prior to the catastrophic event. The trace element data (e.g. Lu/Sc, Y/Hf, Dy/Y) for the individual zircons in the dacitic/monzonitic units and erupted rhyolite record a continuous trend that is interpreted to reflect crystal fractionation. The combination of zircon U-Pb dating and trace element analyses also allows us to trace the apparent timing and duration of the rhyolite melt extraction from the intermediate mush, as the trace element ratios for the rhyolite diverge from those of the DPI approx. 100-150 kyrs. before eruption. This protracted timescale for building an intermediate mush large enough to hold 500 km3 of rhyolite is consistent with that observed for other large ignimbrites in arc settings.

  20. Rates and Mechanisms of Solidification in Large Magma Bodies: Implications for Melt Extraction in all Tectonic Settings

    NASA Astrophysics Data System (ADS)

    VanTongeren, J. A.

    2013-12-01

    As is observed in both experiment and theory, in the absence of hydrothermal convection, the majority of magma chamber heat loss occurs via conduction through the roof of the intrusion and into the cold country rock above. The formation of an upper solidification front (or Upper Border Series, UBS), recorded in the rocks both geochemically and texturally, is a natural outcome of the progression of the solidification front from the cold roof to the hot center of the magma chamber. There are, however, a few unique layered mafic intrusions for which little or no UBS exists. In this study, I examine the thermal evolution and crystallization rates of several classic layered intrusions as it is recorded in the extent of the preserved UBS. For those intrusions that have experienced crystallization at the roof, such as the Skaergaard Intrusion, the development of a UBS reduces the temperature gradient at the roof and effectively slows the rate of heat loss from the main magma body. However, for those intrusions that do not have an UBS, such as the Bushveld Complex, the cooling rate is controlled only by the maximum rate of conductive heat loss through the overlying roof rocks, which decreases with time. The implications are two-fold: (1) The relative thickness of the UBS in large intrusions may be the key to quantifying their cooling and solidification rates; and (2) The nature of the magma mush zone near the roof of an intrusion may depend principally on the long-term thermal evolution of the magma body. Particularly at the end stages of crystallization, when the liquids are likely to be highly evolved and high viscosities may inhibit convection, intrusions lacking a well-defined UBS may provide important insights into the mechanics of crystal-liquid separation, melt extraction, and compaction in felsic plutons as well as mafic intrusions. These results are important for long-lived (>500 kyr) or repeatedly replenished magma chambers in all tectonic settings.

  1. Tape casting fabrication and properties of planar waveguide YAG/Yb:YAG/YAG transparent ceramics

    NASA Astrophysics Data System (ADS)

    Zhao, Yu; Liu, Qiang; Ge, Lin; Wang, Chao; Li, Wenxue; Yang, Chao; Wang, Juntao; Yuan, Lei; Xie, Tengfei; Kou, Huamin; Pan, Yubai; Gao, Qingsong; Bo, Yong; Peng, Qinjun; Xu, Zuyan; Li, Jiang

    2017-07-01

    Highly transparent YAG/10at.%Yb:YAG/YAG planar waveguide ceramics were fabricated by the non-aqueous tape casting and solid-state reactive sintering technology. The tapes are relatively homogeneous and the green body shows a dense structure without distinct interfaces after the treatment of debinding and cold isostatic pressing. YAG/10at.%Yb:YAG/YAG ceramics with almost full dense structure were obtained by vacuum-sintering at 1760 °C for 30 h. For the mirror-polished sample with the thickness of 3.5 mm, the In-line transmittance was measured to be 83.6% at the visual wavelength of 400 nm. The diffusion distance of the Yb3+ ions was about 215 μm along the thickness direction of the ceramics. In the lasing experiments, the YAG/10at.%Yb:YAG/YAG planar waveguide ceramics were end-pumped by a 976 nm semiconductor diode laser and enabled efficient continuous-wave lasers, which resulted in a maximum output power of 1.6 W and a slope efficiency of 34.4% at 1030 nm.

  2. Timescale of silicic melt extraction/transport by diking from shallow intermediate crystalline-rich reservoirs: numerical modelling and case study

    NASA Astrophysics Data System (ADS)

    Gutiérrez, F. J.; Aravena, A.; Payacán, I. J.; Parada, M. Á.; Bachmann, O.

    2016-12-01

    We performed time-dependent numerical modelling of a cooling shallow magma reservoir of intermediate composition with a particular emphasis on the late-stage silicic melt extraction/transportation through dikes from a crystalline-rich mush formed during the late magmatic stage. Results show that timescales of silicic melt extraction/transport is a relatively short event consistent with crystal settling and compaction processes. We select the 10-12 Ma La Gloria pluton (LGP) as a study case of a shallow slightly zoned granodioritic pluton where leucogranitic dikes are ubiquitous in the pluton and neighboring host rocks. Simulation results indicate that, to preserve the LGP reservoir over the solidus for over 1 Ma, a continuous injection of intermediate magma is required. Residual melt extraction/transport through dikes are only possible during the last thousands of years at rates of 4-8 10-3 km3/yr, leaving a record of accumulated mineral and compositional zonation in the reservoir. According to thermal models, the mentioned modelled rates are similar than to the injection rates needed to build and maintain large silicic mushes at shallower levels. However, we suggest that it is unlikely that a small magma reservoir like LGP has fed a large silicic volcanism (>100 km3 volume), but rather low-volume silicic intrusions, such as sills and dikes preserved at higher levels, or by moderate to small volcanic eruptions (<1 km3 volume).

  3. Effect of Er:YAG laser energy on the morphology of enamel/adhesive system interface

    NASA Astrophysics Data System (ADS)

    Delfino, Carina Sinclér; Souza-Zaroni, Wanessa Christine; Corona, Silmara Aparecida Milori; Pécora, Jesus Djalma; Palma-Dibb, Regina Guenka

    2006-10-01

    The aim of this study was to evaluate in vitro the influence of Er:YAG laser energy variation to cavity preparation on the morphology of enamel/adhesive system interface, using SEM. Eighteen molars were used and the buccal surfaces were flattened without dentine exposure. The specimens were randomly assigned to two groups, according to the adhesive system (conventional total-etching or self-etching), and each group was divided into three subgroups (bur carbide in turbine of high rotation, Er:YAG laser 250 mJ/4 Hz and Er:YAG laser 300 mJ/4 Hz) containing six teeth each. The enamel/adhesive system interface was serially sectioned and prepared for SEM. The Er:YAG laser, in general, produced a more irregular adhesive interface than the control group. For Er:YAG laser 250 mJ there was formation of a more regular hybrid layer with good tag formation, mainly in the total-etching system. However, Er:YAG laser 300 mJ showed a more irregular interface with amorphous enamel and fused areas, for both adhesive systems. It was concluded that cavity preparation with Er:YAG laser influenced on the morphology of enamel/adhesive system interface and the tissual alterations were more evident when the energy was increased.

  4. Amorphic complexity

    NASA Astrophysics Data System (ADS)

    Fuhrmann, G.; Gröger, M.; Jäger, T.

    2016-02-01

    We introduce amorphic complexity as a new topological invariant that measures the complexity of dynamical systems in the regime of zero entropy. Its main purpose is to detect the very onset of disorder in the asymptotic behaviour. For instance, it gives positive value to Denjoy examples on the circle and Sturmian subshifts, while being zero for all isometries and Morse-Smale systems. After discussing basic properties and examples, we show that amorphic complexity and the underlying asymptotic separation numbers can be used to distinguish almost automorphic minimal systems from equicontinuous ones. For symbolic systems, amorphic complexity equals the box dimension of the associated Besicovitch space. In this context, we concentrate on regular Toeplitz flows and give a detailed description of the relation to the scaling behaviour of the densities of the p-skeletons. Finally, we take a look at strange non-chaotic attractors appearing in so-called pinched skew product systems. Continuous-time systems, more general group actions and the application to cut and project quasicrystals will be treated in subsequent work.

  5. Melt extraction and metasomatism recorded in basal peridotites above the metamorphic sole of the northern Fizh massif, Oman ophiolite

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Masako; Python, Marie; Tamura, Akihiro; Arai, Shoji; Takazawa, Eiichi; Shibata, Tomoyuki; Ueda, Akira; Sato, Tsutomu

    2015-05-01

    The Oman ophiolite is one of the best preserved sections of oceanic crust and upper mantle worldwide, and consists of multiple massifs that lie along more than 400 km of the Arabian coast. In the northernmost massifs, the oceanic crust preserves a record of polygenetic magmatism from mid-ocean ridge to subduction-related stages. The lherzolites and clinopyroxene (Cpx)-rich harzburgites of the Fizh block are located a few tens to a hundred meters above the metamorphic sole of the ophiolite and the geochemistry of these Cpx-rich peridotites provides evidence of a genetic link between oceanic crust and mantle. These Cpx-rich peridotites contain olivine with a restricted range of forsterite contents (90-91), but variable Cr-spinel Cr# (Cr/(Cr + Al) atomic ratio) values (0.12-0.33), suggesting that these Cpx-rich peridotites have undergone variable degrees of melt extraction. Cpxs within the Cpx-rich peridotites have chondrite-normalised trace element variation patterns that slope either gently or steeply between the heavy rare earth elements (REEs) and the middle REEs ((Sm/Yb)N = 0.08-0.55, where N chondrite-normalised) and are enriched in highly incompatible elements such as Rb, Ba and Nb. This Cpx chemistry can be explained by a polygenetic evolution whereby an initial 4-12% of melt was extracted from the depleted mantle source before this mantle was metasomatised by interaction with fluids derived from dehydration of the metamorphic sole during subduction initiation and obduction. A comparison between 143Nd/144Nd versus 147Sm/144Nd for Cpx in the Fizh basal Cpx-rich peridotites and a mineral-whole rock Sm-Nd isochron for a gabbro from the same massif suggests a genetic link between crustal and mantle rocks in this area. In addition, Cpxs within the basal Cpx-rich peridotites have highly variable Sr isotopic compositions that are indicative of a significant contribution of seawater from the metamorphic sole, originally derived from subducted oceanic crustal material.

  6. Melt extraction from crystal mushes: Numerical model of texture evolution and calibration of crystallinity-ordering relationships

    NASA Astrophysics Data System (ADS)

    Špillar, Václav; Dolejš, David

    2015-12-01

    sparse crystal suspensions. Illustrative quantitative evaluation of the crystallinity-clustering relationships to representative porphyritic granites from a single intrusive unit of the Krkonoše-Jizera pluton (central Europe) reveals a single crystal accumulation path starting at low initial crystallinity (5-7 vol.% K-feldspar phenocrysts), with 24-84% melt extracted leading to the observed crystallinity of 9-26 vol.%. By contrast, a camptonite dyke from the České středohoří volcanic province has experienced the onset of crystal accumulation later (18 vol.% amphibole crystals) and lost 23% interstitial melt only. The combination of modal and clustering analysis offers a sensitive tool for identifying differentiation processes in natural magma chambers, and here it illustrates examples of mechanically dominated open-system vs. in situ nearly closed-system crystallization from two contrasting magmatic settings.

  7. Melt extraction and mantle source at a Southwest Indian Ridge Dragon Bone amagmatic segment on the Marion Rise

    NASA Astrophysics Data System (ADS)

    Gao, Changgui; Dick, Henry J. B.; Liu, Yang; Zhou, Huaiyang

    2016-03-01

    This paper works on the trace and major element compositions of spatially associated basalts and peridotites from the Dragon Bone amagmatic ridge segment at the eastern flank of the Marion Platform on the ultraslow spreading Southwest Indian Ridge. The rare earth element compositions of basalts do not match the pre-alteration Dragon Bone peridotite compositions, but can be modeled by about 5 to 10% non-modal batch equilibrium melting from a DMM source. The Dragon Bone peridotites are clinopyroxene-poor harzburgite with average spinel Cr# 27.7. The spinel Cr# indicates a moderate degree of melting. However, CaO and Al2O3 of the peridotites are lower than other abyssal peridotites at the same Mg# and extent of melting. This requires a pyroxene-poor initial mantle source composition compared to either hypothetical primitive upper mantle or depleted MORB mantle sources. We suggest a hydrous melting of the initial Dragon Bone mantle source, as wet melting depletes pyroxene faster than dry. According to the rare earth element patterns, the Dragon Bone peridotites are divided into two groups. Heavy REE in Group 1 are extremely fractionated from middle REE, which can be modeled by 7% fractional melting in the garnet stability field and another 12.5 to 13.5% in the spinel stability field from depleted and primitive upper mantle sources, respectively. Heavy REE in Group 2 are slightly fractionated from middle REE, which can be modeled by 15 to 20% fractional melting in the spinel stability field from a depleted mantle source. Both groups show similar melting degree to other abyssal peridotites. If all the melt extraction occurred at the middle oceanic ridge where the peridotites were dredged, a normal 6 km thick oceanic crust is expected at the Dragon Bone segment. However, the Dragon Bone peridotites are exposed in an amagmatic ridge segment where only scattered pillow basalts lie on a partially serpentinized mantle pavement. Thus their depletion requires an earlier melting

  8. Probing depth dependencies of melt emplacement on time dependent quantities in a continental rift scenario with melting and melt extraction

    NASA Astrophysics Data System (ADS)

    Wallner, Herbert; Schmeling, Harro

    2014-05-01

    Since some years seismological observations provide increasing evidence of a discontinuity near the mid of older mantle lithosphere. Explanation may be a melt infiltration front (MIF) as upper margin of an evolving network of veins. These are formed by crystallized melt supplied by episodic melting events in the asthenosphere. To test this concept geodynamically we performed numerical modelling applying melting, extraction of melt and emplacement in a viscous matrix. Thereupon, we were faced to the problem defining an intrusion level for the melt. Findings of prior studies led to the need of movable, process dependent boundaries of the emplacement zone additionally making the process probably more self-consistent. Here we present a preliminary study exploring several empirical attempts to relate time dependent states to an upward moving boundary for intrusion. Modeled physics is based on thermo-mechanics of visco-plastic flow. The equations of conservation of mass, momentum and energy are solved for a multi component (crust-mantle) and two phase (melt-matrix) system. Rheology is temperature-, pressure-, and stress-dependent. In consideration of depletion and enrichment melting and solidification are controlled by a simplified linear binary solid solution model. The Compaction Boussinesq Approximation and the high Prandtl number approximation are used, elasticity is neglected and geometry is restricted to 2D. Approximation is done with the Finite Difference Method with markers in an Eulerian formulation (FDCON). Model guiding scenario is a extending thick lithosphere associated to by updoming asthenosphere probably additionally heated by a plume nearby. As the P-T conditions in the asthenosphere are near the solidus caused changes may increase melting and generate partial melt. Against conventional expectations on permeability at lithosphere-asthenosphere boundary (LAB) depth a fast melt transport into and sometimes through the lithosphere often is observed. The

  9. Holmium:YAG surgical lasers.

    PubMed

    1995-03-01

    "Holmium:YAG (Ho:YAG)" is the shorthand name for a family of solid-state lasers that use the doping element holmium in a laser crystal (e.g., YAG [yttrium-aluminum-garnet]) and that emit energy at approximately 2.1 microns. This wavelength is relatively new to medicine and has been used in laser surgery for only about the last six years. Like the carbon dioxide (CO2) laser when it was first used clinically, the Ho:YAG laser is poised for rapid and wide-spread use. Ho:YAG lasers, like CO2 lasers, offer precise cutting with minimal damage to adjacent tissue; however, unlike CO2 lasers, they also offer fiberoptic delivery (which is ideal for endoscopic use) and the ability to treat tissue in a liquid-filled environment (e.g., saline, blood). The initial specialty for which the Ho:YAG laser was used was arthroscopic surgery, especially diskectomy. Today, it is effectively used in many surgical specialties, including general surgery, urology, laparoscopy, neurosurgery, lithotripsy, angioplasty, orthopedic surgery (which includes procedures such as meniscectomy, bone sculpting [may also be performed in plastic surgery], and some experimental surgery, such as cartilage shrinking to tighten loose joints), and dentistry. Because of its broad range of potential applications, it has been called the "Swiss Army Knife" of lasers. High-powered Ho:YAG lasers, which enable surgeons to work more quickly and cut more smoothly, have been made available only within the last three years (units offering > 20 W) to 18 months (units offering > 60 W). Because of this rapid increase, high-powered units are still relatively expensive, and it is not yet clear whether maximum power outputs will continue to increase or whether the cost of higher-power units will begin to come down. Although low-power and high-power Ho:YAG lasers can be used for the same procedures, their different ranges of possible clinical techniques make them better suited to different applications: low-power units are

  10. YAG aerosol lidar

    NASA Technical Reports Server (NTRS)

    Sullivan, R.

    1988-01-01

    The Global Atmospheric Backscatter Experiment (GLOBE) Mission, using the NASA DC-8 aircraft platform, is designed to provide the magnitude and statistical distribution of atmospheric backscatter cross section at lidar operating wavelengths. This is a fundamental parameter required for the Doppler lidar proposed to be used on a spacecraft platform for global wind field measurements. The prime measurements will be made by a CO2 lidar instrument in the 9 to 10 micron range. These measurements will be complemented with the Goddard YAG Aerosol Lidar (YAL) data in two wavelengths, 0.532 and 1.06 micron, in the visible and near-infrared. The YAL, is being designed to utilize as much existing hardware, as feasible, to minimize cost and reduce implementation time. The laser, energy monitor, telescope and detector package will be mounted on an optical breadboard. The optical breadboard is mounted through isolation mounts between two low boy racks. The detector package will utilize a photomultiplier tube for the 0.532 micron channel and a silicon avalanche photo detector (APD) for the 1.06 micron channel.

  11. Amorphous metal composites

    DOEpatents

    Byrne, Martin A.; Lupinski, John H.

    1984-01-01

    An improved amorphous metal composite and process of making the composite. The amorphous metal composite comprises amorphous metal (e.g. iron) and a low molecular weight thermosetting polymer binder. The process comprises placing an amorphous metal in particulate form and a thermosetting polymer binder powder into a container, mixing these materials, and applying heat and pressure to convert the mixture into an amorphous metal composite.

  12. Erbium: YAG laser lithotripsy mechanism.

    PubMed

    Chan, Kin Foong; Lee, Ho; Teichman, Joel M H; Kamerer, Angela; McGuff, H Stan; Vargas, Gracie; Welch, Ashley J

    2002-08-01

    We tested the hypothesis that the mechanism of long pulse erbium:YAG laser lithotripsy is photothermal. Human urinary calculi were placed in deionized water and irradiated with erbium:YAG laser energy delivered through a sapphire optical fiber. Erbium:YAG bubble dynamics were visualized with Schlieren flash photography and correlated to acoustic emissions measured by a polyvinylidene fluoride needle hydrophone. The sapphire fiber was placed either parallel or perpendicular to the calculus surface to assess the contribution of acoustic transients to fragmentation. Stones were irradiated using desiccated stone irradiated in air, hydrated stone irradiated in air and hydrated stone irradiated in water. Ablation crater sizes were compared. Uric acid stones were irradiated in water and the water was assayed for cyanide. During the early phase of vapor bubble expansion, acoustic transients had minimal effects on calculus fragmentation. Fragmentation occurred due to direct absorption of laser energy transmitted to the calculus through the vapor channel between the sapphire fiber tip and calculus. The forward axial expansion of the bubble occurred more rapidly than the radial expansion. A parallel oriented fiber on the calculus surface produced no fragmentation but generated larger amplitude acoustic transients compared to perpendicular orientation. In perpendicular orientation the erbium:YAG laser did not generate any collapse acoustic waves but fragmentation occurred. Crater width was greatest for desiccated stones irradiated in air (p <0.03). Cyanide production increased as erbium:YAG irradiation of uric acid calculi increased, (r2 = 0.98). The erbium:YAG laser fragments stones through a photothermal mechanism.

  13. Spectroscopic characterization of YAG and Nd:YAG single crystals

    NASA Astrophysics Data System (ADS)

    Kostić, S.; Lazarević, Z.; Romčević, M.; Radojević, V.; Milutinović, A.; Stanišić, G.; Gilić, M.

    2014-09-01

    In this paper, we used the Czochralski method to obtain good quality yttrium aluminium garnet (YAG, Y3Al5O12) and yttrium aluminium garnet doped with neodymium (Nd:YAG) crystals. The investigations were based on the growth mechanisms and the shape of the liquid/solid interface crystallization front on the crystal properties and incorporation of Nd3+ ions. The obtained single YAG and Nd:YAG crystals were studied by use of x-ray diffraction, Raman and IR spectroscopy. There are strong metal oxygen vibrations in the region of 650-800 cm-1 which are characteristics of Al-O bond: peaks at 784/854, 719/763 and 691/707 cm-1 correspond to asymmetric stretching vibrations in tetrahedral arrangement. Peaks at 566/582, 510/547 and 477/505 cm-1 are asymmetric stretching vibrations and 453/483 cm-1 is the symmetric vibration of the Al-O bond in octahedral arrangements of the garnet structure. Lower energy peaks correspond to translation and vibration of cations in different coordinations—tetrahedral, octahedral and dodecahedral in the case of the lowest modes.

  14. Q-switched Nd:YAG/V:YAG monolith microlaser

    NASA Astrophysics Data System (ADS)

    Sulc, Jan; Jelinkova, Helena; Nejezchleb, Karel; Skoda, Vaclav

    2005-03-01

    A specially developed monolith crystal, which combines in one piece cooling undoped part (undoped YAG crystal), active laser part (YAG crystal doped with Nd3+ ions) and saturable absorber (YAG crystal doped with V3+ ions), was used for construction of longitudinally diode pumped Q-switched Nd:YAG laser operating at wavelength 1342 nm. The monolith consists of 4 mm long undoped part bounded to the V:YAG saturable absorber 530 μm thick which gives the initial transmission of saturable absorber 88%. The diameter of whole monolith was 5 mm. This combination of active crystal and saturable absorber allows to realize more compact resonator with the shortest cavity length of 33 mm only. The monolith was mounted in an adjustable water-cooled cupreous ring. Temperature of cooling water was in a range from 12 to 14 °C. As a pumping source the CW-operating laser diode emitting radiation at wavelength 808 nm with the maximum output power 20 W at the end of the fiber (fiber core diameter 400 &mum, numerical aperture 0.22) was used. The diode radiation was focused into the active Nd:YAG crystal by two achromatic doublet lenses with the focal length of 75 mm. The measured diameter of pumping beam focus inside the crystal was 360 μm. The resonator of the Nd:YAG laser was formed by a planar dielectric mirror with high transmission for the pumping radiation (T>98%@808nm) together with the high reflectance for the generated radiation (R=100%@1340nm), and by a concave (100mm or 146 mm) dielectric mirror serving as an output coupler. As this coupler a various dielectric reflectors (with the reflectivity from 82% up to 94%) was used with the reason to obtain the shortest giant pulse with the maximum power. As the optimal, the stable CW Q-switched output at wavelength 1342 nm with length of pulses 11 ns with repetition rate 6.4kHz and peak power 6.1kW, was obtained.

  15. Ceramic planar waveguide laser of non-aqueous tape casting fabricated YAG/Yb:YAG/YAG

    PubMed Central

    Wang, Chao; Li, Wenxue; Yang, Chao; Bai, Dongbi; Li, Jiang; Ge, Lin; Pan, Yubai; Zeng, Heping

    2016-01-01

    Ceramic YAG/Yb:YAG/YAG planar waveguide lasers were realized on continuous-wave and mode-locked operations. The straight waveguide, fabricated by non-aqueous tape casting and solid state reactive sintering, enabled highly efficient diode-pumped waveguide continuous-wave laser with the slope efficiency of 66% and average output power of more than 3 W. The influence of the waveguide structure on the wavelength tunability was also experimentally investiccgated with a dispersive prism. Passively mode-locked operation of the ceramic waveguide laser was achieved by using a semiconductor saturable absorber mirror (SESAM), output 2.95 ps pulses with maximum power of 385 mW at the central wavelength of 1030 nm. PMID:27535577

  16. High power YAG/Nd:YAG/YAG ceramic planar waveguide laser

    NASA Astrophysics Data System (ADS)

    Rao, Han; Liu, Zhaojun; Cong, Zhenhua; Huang, Qingjie; Liu, Yang; Zhang, Sasa; Zhang, Xingyu; Feng, Chao; Wang, Qingpu; Ge, Lin; Li, Jiang

    2017-04-01

    A high power YAG/Nd:YAG/YAG ceramic planar waveguide laser was demonstrated. For continuous wave regime, a maximum output power of 10.4 W at a center wavelength of 1064.6 nm was obtained under an absorbed pump power of 17.4 W, corresponding to an optical-to-optical conversion efficiency of 59.8%. For acousto-optically Q-switched operation, we obtained 2.5 W of output power at a pulse repetition frequency of 10 kHz. The pulse duration was 6.5 ns with peak power and pulse energy of 38.5 kW and 0.25 mJ, respectively.

  17. Partial melting of garnet lherzolite with water and carbon dioxide at 3 GPa using a new melt extraction technique: implications for intraplate magmatism

    NASA Astrophysics Data System (ADS)

    Baasner, Amrei; Médard, Etienne; Laporte, Didier; Hoffer, Géraldine

    2016-05-01

    The origin and source rocks of alkali-rich and SiO2-undersatured magmas in the Earth's upper mantle are still under debate. The garnet signature in rare earth element patterns of such magmas suggests a garnet-bearing source rock, which could be garnet lherzolite or garnet pyroxenite. Partial melting experiments were performed at 2.8 GPa and 1345-1445 °C in a piston-cylinder using mixtures of natural lherzolite with either 0.4 wt% H2O and 0.4 wt% CO2 or 0.7 wt% H2O and 0.7 wt% CO2. Different designs of AuPd capsules were used for melt extraction. The most successful design included a pentagonally shaped disc placed in the top part of the capsule for sufficient melt extraction. The degrees of partial melting range from 0.2 to 0.04 and decrease with decreasing temperature and volatile content. All samples contain olivine and orthopyroxene. The amounts of garnet and clinopyroxene decrease with increasing degree of partial melting until both minerals disappear from the residue. Depending on the capsule design, the melts quenched to a mixture of quench crystals and residual glass or to glass, allowing measurement of the volatile concentrations by Raman spectroscopy. The compositions of the partial melts range from basalts through picrobasalts to foidites. Compared to literature data for melting of dry lherzolites, the presence of H2O and CO2 reduces the SiO2 concentration and increases the MgO concentration of partial melts, but it has no observable effect on the enrichment of Na2O in the partial melts. The partial melts have compositions similar to natural melilitites from intraplate settings, which shows that SiO2-undersaturated intraplate magmas can be generated by melting of garnet lherzolite in the Earth's upper mantle in the presence of H2O and CO2.

  18. Theory of amorphous ices

    PubMed Central

    Limmer, David T.; Chandler, David

    2014-01-01

    We derive a phase diagram for amorphous solids and liquid supercooled water and explain why the amorphous solids of water exist in several different forms. Application of large-deviation theory allows us to prepare such phases in computer simulations. Along with nonequilibrium transitions between the ergodic liquid and two distinct amorphous solids, we establish coexistence between these two amorphous solids. The phase diagram we predict includes a nonequilibrium triple point where two amorphous phases and the liquid coexist. Whereas the amorphous solids are long-lived and slowly aging glasses, their melting can lead quickly to the formation of crystalline ice. Further, melting of the higher density amorphous solid at low pressures takes place in steps, transitioning to the lower-density glass before accessing a nonequilibrium liquid from which ice coarsens. PMID:24858957

  19. Nd:YAG laser in kidney surgery

    NASA Astrophysics Data System (ADS)

    Gomula, Andrzej

    1996-03-01

    The paper presents the way laser light affects tissue, especially kidney tissue. Animal experiments include the use of Nd:YAG laser in kidney surgery. When the outcome of these experiments turned out to be good Nd:YAG laser was used to operate on kidneys in 45 human patients. The results of a five-year follow-up period of these patients let Nd:YAG laser be considered a good tool to cut and coagulate renal parenchyma.

  20. Nd:YAG and HO:YAG laser

    NASA Astrophysics Data System (ADS)

    Oswal, V. H.

    1994-02-01

    Among the commonly available surgical lasers, the CO2 laser has acquired a unique role in oral, laryngeal, and tracheo-bronchial surgery. Other wavelengths, and in particular, frequency doubled Nd:YAG laser, the KTP-532 is also gaining ground, offering the advantage of the fiber transmissivity. A number of new lasers are being introduced. The question of their usefulness in the field of otolaryngology can best be answered by systematic study of the peculiar requirement of the surgical procedure, the tissue interactions of any particular wavelength/s, the ease with which the beam can be targeted, and so on.

  1. Nanocrystal dispersed amorphous alloys

    NASA Technical Reports Server (NTRS)

    Perepezko, John H. (Inventor); Allen, Donald R. (Inventor); Foley, James C. (Inventor)

    2001-01-01

    Compositions and methods for obtaining nanocrystal dispersed amorphous alloys are described. A composition includes an amorphous matrix forming element (e.g., Al or Fe); at least one transition metal element; and at least one crystallizing agent that is insoluble in the resulting amorphous matrix. During devitrification, the crystallizing agent causes the formation of a high density nanocrystal dispersion. The compositions and methods provide advantages in that materials with superior properties are provided.

  2. Tritium in amorphous silicon

    SciTech Connect

    Sidhu, L.S.; Kosteski, T.; O`Leary, S.K.; Gaspari, F.; Zukotynski, S.; Kherani, N.P.; Shmadya, W.

    1996-12-31

    Preliminary results on infrared and luminescence measurements of tritium incorporated amorphous silicon are reported. Tritium is an unstable isotope that readily substitutes hydrogen in the amorphous silicon network. Due to its greater mass, bonded tritium is found to introduce new stretching modes in the infrared spectrum. Inelastic collisions between the beta particles, produced as a result of tritium decay, and the amorphous silicon network, results in the generation of excess electron-hole pairs. Radiative recombination of these carriers is observed.

  3. Silver arsenate amorphous electrolyte batteries: conduction characteristics and electrochemical performance

    NASA Astrophysics Data System (ADS)

    Sathya Sainath Prasad, P.; Rambabu, B.

    Transport properties of silver ion conducting ternary amorphous solid electrolytes, XAgI[(1 - X)( yAg 2O zAs 2O 3)] and XAgI[(1 - X)( yAg 2O zAs 2O 5)] for 30⩽ X⩽70 mol% AgI and 0.20 ⩽( z/y) ⩽3.0 were characterized in a two step process to determine the highest ion conducting composition. Interesting results were obtained by the variation of Glass Former to Glass Modifier ratio ( z/y) and AgI content ( X). Some of the results were previously reported with z/y as a variable parameter for a constant concentration of X. The values of z/y were maintained at the best conducting compositions as derived from the previous work, and the present study reports the conduction characteristics with X as a variable parameter. The best conducting amorphous electrolytes in these two systems were used in the fabrication of solid-state batteries, and their electrochemical performance has been evaluated. A comparison of the solid-state cells with amorphous and polycrystalline electrolytes was undertaken with regard to the current discharge profiles and the cell capacities.

  4. Environmentally benign processing of YAG transparent wafers

    NASA Astrophysics Data System (ADS)

    Yang, Yan; Wu, Yiquan

    2015-12-01

    Transparent yttrium aluminum garnet (YAG) wafers were successfully produced via aqueous tape casting and vacuum sintering techniques using a new environmentally friendly binder, a copolymer of isobutylene and maleic anhydride with the commercial name ISOBAM (noted as ISOBAM). Aqueous YAG slurries were mixed by ball-milling, which was followed by de-gassing and tape casting of wafers. The final YAG green tapes were homogenous and flexible, and could be bent freely without cracking. After the drying and sintering processes, transparent YAG wafers were achieved. The microstructures of both the green tape and vacuum-sintered YAG ceramic were observed by scanning electronic microscopy (SEM). Phase compositions were examined by X-ray diffraction (XRD). Optical transmittance was measured in UV-VIS regions with the result that the transmittance is 82.6% at a wavelength of 800 nm.

  5. Pattern of healing of calvarial bone in the rat following application of the erbium-YAG laser.

    PubMed

    el Montaser, M A; Devlin, H; Sloan, P; Dickinson, M R

    1997-01-01

    The aim of this study was to examine the pattern of healing in rat calvarial defects prepared with the erbium-YAG laser, using the "guided tissue regeneration" technique [Dahlin et al., Scand J Plast Reconstr Hand Surg 1990;24: 13-19]. PTFE membranes were placed over the lased skull defects and the skin wounds sutured. Rats were killed humanely at intervals after surgery and the skulls processed for paraffin wax histology. A further group of mature rats was killed humanely and the calvariae removed. Slots were prepared using the erbium-YAG laser and immediately examined under the environmental scanning electron microscope (ESEM) in hydrated conditions, which avoided drying artefact. An amorphous, mineral-rich carbon layer surrounds the lased bone defect, which in the in vivo experiments was seen as a basophilic zone that was resistant to resorption. Bone infilling of the lased defect was retarded by delayed resorption of the amorphous, mineral-rich carbon layer.

  6. Healing of bone in the rat following surgery with the erbium-YAG laser

    NASA Astrophysics Data System (ADS)

    Dickinson, Mark R.; Devlin, Hugh; El Montaser, Monsour A.; Sloan, Philip

    1996-12-01

    Background and objectives: the aim of this study was to examine the pattern of healing in rat calvarial defects prepared with the erbium-YAG laser, using the 'guided tissue regeneration' technique. Materials and method: PTFE membranes were placed over lased skull defects, and the skin wounds sutured. Rats were killed humanely at intervals after surgery, and the skulls processed for paraffin wax histology. A further group of mature rats were also killed humanely and the calvariae removed. Slots were prepared using the erbium-YAG laser and immediately examined under the environmental scanning electron microscope (ESEM) in hydrated conditions, which avoided drying artifacts. Results: An amorphous, mineral-rich carbon layer surrounds the lased bone defect, which in the in vivo experiments was seen as a basophilic zone which was resistant to resorption.

  7. Trehalose amorphization and recrystallization.

    PubMed

    Sussich, Fabiana; Cesàro, Attilio

    2008-10-13

    The stability of the amorphous trehalose prepared by using several procedures is presented and discussed. Amorphization is shown to occur by melting (T(m)=215 degrees C) or milling (room temperature) the crystalline anhydrous form TRE-beta. Fast dehydration of the di-hydrate crystalline polymorph, TRE-h, also produces an amorphous phase. Other dehydration procedures of TRE-h, such as microwave treatment, supercritical extraction or gentle heating at low scan rates, give variable fractions of the polymorph TRE-alpha, that undergo amorphization upon melting (at lower temperature, T(m)=130 degrees C). Additional procedures for amorphization, such as freeze-drying, spray-drying or evaporation of trehalose solutions, are discussed. All these procedures are classified depending on the capability of the undercooled liquid phase to undergo cold crystallization upon heating the glassy state at temperatures above the glass transition temperature (T(g)=120 degrees C). The recrystallizable amorphous phase is invariably obtained by the melt of the polymorph TRE-alpha, while other procedures always give an amorphous phase that is unable to crystallize above T(g). The existence of two different categories is analyzed in terms of the transformation paths and the hypothesis that the systems may exhibit different molecular mobilities.

  8. Hydrogen in amorphous silicon

    SciTech Connect

    Peercy, P. S.

    1980-01-01

    The structural aspects of amorphous silicon and the role of hydrogen in this structure are reviewed with emphasis on ion implantation studies. In amorphous silicon produced by Si ion implantation of crystalline silicon, the material reconstructs into a metastable amorphous structure which has optical and electrical properties qualitatively similar to the corresponding properties in high-purity evaporated amorphous silicon. Hydrogen studies further indicate that these structures will accomodate less than or equal to 5 at.% hydrogen and this hydrogen is bonded predominantly in a monohydride (SiH/sub 1/) site. Larger hydrogen concentrations than this can be achieved under certain conditions, but the excess hydrogen may be attributed to defects and voids in the material. Similarly, glow discharge or sputter deposited amorphous silicon has more desirable electrical and optical properties when the material is prepared with low hydrogen concentration and monohydride bonding. Results of structural studies and hydrogen incorporation in amorphous silicon were discussed relative to the different models proposed for amorphous silicon.

  9. Passively Q-switched ceramic Nd3+:YAG/Cr4+:YAG lasers.

    PubMed

    Feng, Yan; Lu, Jianren; Takaichi, Kazunori; Ueda, Ken-ichi; Yagi, Hideki; Yanagitani, Takagimi; Kaminskii, Alexander A

    2004-05-10

    Passively Q-switched ceramic Nd3+:YAG lasers with ceramic Cr4+:YAG saturable absorbers are demonstrated. When the lasers are pumped by a 1-W cw laser diode, optical-optical efficiency as great as 22% is obtained with Cr4+:YAG of initial transmission ranging from 94% to 79%. The results are similar to those in their crystalline counterparts. The operation of Brewster's angle and the polarization state of the laser output are also investigated.

  10. Amorphous pharmaceutical solids.

    PubMed

    Vranić, Edina

    2004-07-01

    Amorphous forms are, by definition, non-crystalline materials which possess no long-range order. Their structure can be thought of as being similar to that of a frozen liquid with the thermal fluctuations present in a liquid frozen out, leaving only "static" structural disorder. The amorphous solids have always been an essential part of pharmaceutical research, but the current interest has been raised by two developments: a growing attention to pharmaceutical solids in general, especially polymorphs and solvates and a revived interest in the science of glasses and the glass transition. Amorphous substances may be formed both intentionally and unintentionally during normal pharmaceutical manufacturing operations. The properties of amorphous materials can be exploited to improve the performance of pharmaceutical dosage forms, but these properties can also give rise to unwanted effects that need to be understood and managed in order for the systems to perform as required.

  11. Amorphous diamond films

    DOEpatents

    Falabella, S.

    1998-06-09

    Amorphous diamond films having a significant reduction in intrinsic stress are prepared by biasing a substrate to be coated and depositing carbon ions thereon under controlled temperature conditions. 1 fig.

  12. Progress in ceramic Nd: YAG laser

    NASA Astrophysics Data System (ADS)

    Ikesue, A.; Aung, Yan Lin

    2007-04-01

    We report the first demonstration of polycrystalline Nd:YAG (Y 3Al 5O 12), and Nd-doped YAG single crystal with almost perfect pore-free structure by advanced ceramic processing. The laser conversion efficiency of pore-free polycrystalline Nd and Yb doped ceramics is extremely high, and their optical qualities are comparable to that of commercial high quality Nd:YAG single crystal. We have succeeded also in the fabrication of Nd:YAG single crystal, which can be used for laser oscillation, by solid-state reaction method. Laser oscillation efficiency was very low when pores were remained inside single crystal, however the laser oscillation efficiency of pore-free Nd:YAG single crystal was slightly higher than that of polycrystalline Nd:YAG ceramics having high optical quality. From this fact, it was recognized that the optical scattering occurs mainly at the residual pores inside the Nd:YAG ceramics, and the scattering at the grain boundary is very little. In addition, we confirmed that Nd heavily-doped YAG single crystal can be fabricated by sintering method. We have demonstrated the fabrication of composite ceramic with complicated structures without the needs of precise polishing and diffusion bonding. Advanced ceramic processing, which enables design flexibility of laser element, presented in this work is important in the development of high performance laser (high efficiency, high beam quality and high output energy etc.) Moreover, we have recently developed polycrystalline ceramic fiber laser first in the world, and achieved over 8W output per unit length of the fiber.

  13. 75 Micron YAG-Alumina Eutectic Fiber

    DTIC Science & Technology

    2007-11-02

    eutectic produced superior tensile strengths over the YAG rich side but the YAG rich side may produce better creep properties . 14. SUBJECT TERMS 15...that combustor and exhaust system components can operate at temperatures >2400 °F (1316 °C) and become limited by critical material properties such as...important. The application of ceramic matrix composites (CMC’s) to these applications is considered essential for achieving the property and

  14. Cryogenic Yb: YAG Thin-Disk Laser

    DTIC Science & Technology

    2016-09-09

    at room and cryogenic (80°K) temperatures will be presented. The Yb:YAG gain media is cooled using either a pressurized R134A refrigerant system or...thin disk laser performance at room and cryogenic (80°K) temperatures will be presented. The Yb:YAG gain media is cooled using either a pressurized...is thicker than that which would be necessary for room temperature operation. This is to alleviate stresses from the large difference in expansion

  15. Amorphous metal alloy

    DOEpatents

    Wang, R.; Merz, M.D.

    1980-04-09

    Amorphous metal alloys of the iron-chromium and nickel-chromium type have excellent corrosion resistance and high temperature stability and are suitable for use as a protective coating on less corrosion resistant substrates. The alloys are stabilized in the amorphous state by one or more elements of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The alloy is preferably prepared by sputter deposition.

  16. Study of structural and optical properties of YAG and Nd:YAG single crystals

    SciTech Connect

    Kostić, S.; Lazarević, Z.Ž.; Radojević, V.; Milutinović, A.; Romčević, M.; Romčević, N.Ž.; Valčić, A.

    2015-03-15

    Highlights: • Transparent YAG and pale pink Nd:YAG single crystals were produced by the Czochralski technique. • Growth mechanisms and shape of the liquid/solid interface and incorporation of Nd{sup 3+} were studied. • The structure of the crystals was investigated by X-ray diffraction, Raman and IR spectroscopy. • The 15 Raman and 17 IR modes were observed. • The obtained YAG and Nd:YAG single crystals were without core and of good optical quality. - Abstract: Yttrium aluminum garnet (YAG, Y{sub 3}Al{sub 5}O{sub 12}) and yttrium aluminum garnet doped with neodymium (Nd:YAG) single crystals were grown by the Czochralski technique. The critical diameter and the critical rate of rotation were calculated. Suitable polishing and etching solutions were determined. As a result of our experiments, the transparent YAG and pale pink Nd:YAG single crystals were produced. The obtained crystals were studied by X-ray diffraction, Raman and IR spectroscopy. The crystal structure was confirmed by XRD. The 15 Raman and 17 IR modes were observed. The Raman and IR spectroscopy results are in accordance with X-ray diffraction analysis. The obtained YAG and Nd:YAG single crystals were without core and of good optical quality. The absence of a core was confirmed by viewing polished crystal slices. Also, it is important to emphasize that the obtained Nd:YAG single crystal has a concentration of 0.8 wt.% Nd{sup 3+} that is characteristic for laser materials.

  17. Densification behavior, doping profile and planar waveguide laser performance of the tape casting YAG/Nd:YAG/YAG ceramics

    NASA Astrophysics Data System (ADS)

    Ge, Lin; Li, Jiang; Qu, Haiyun; Wang, Juntao; Liu, Jiao; Dai, Jiawei; Zhou, Zhiwei; Liu, Binglong; Kou, Huamin; Shi, Yun; Wang, Zheng; Pan, Yubai; Gao, Qingsong; Guo, Jingkun

    2016-10-01

    The sintering behavior and doping concentration profile of the planar waveguide YAG/Nd:YAG/YAG ceramics by the tape casting and solid-state reaction method were investigated on the basis of densification trajectory, microstructure evolution, and Nd3+ ions diffusion. The porosity of the green body by tape casting and cold isostatic pressing is about 38.6%. And the green bodies were consolidated from 1100 °C to 1800 °C for 0.5-20 h to study the densification and the doping diffusion behaviors. At the temperature higher than 1500 °C, pure YAG phase is formed, followed by the densification and grain growth process. With the increase of temperature, two sintering stages occur, corresponding to remarkable densification and significant grain growth, respectively. The mechanism controlling densification at 1550 °C is grain boundary diffusion. The diffusion of Nd3+ ions is more sensitive to temperature than the sintering time, and the minimum temperature required for the obvious diffusion of Nd3+ ions is higher than 1700 °C. Finally, planar waveguide YAG/1.5 at.%Nd:YAG/YAG transparent ceramics with in-line transmittance of 84.8% at 1064 nm were obtained by vacuum-sintering at 1780 °C for 30 h. The fluorescence lifetime of 4F3/2 state of Nd3+ in the specimen is about 259 μs. The prepared ceramic waveguide was tested in a laser amplifier and the laser pulse was amplificated from 87 mJ to 238 mJ, with the pump energy of 680 mJ.

  18. Passively Q-Switched Yb:YAG Laser with Cr(4+):YAG as the Saturable Absorber.

    PubMed

    Dong, J; Deng, P; Liu, Y; Zhang, Y; Xu, J; Chen, W; Xie, X

    2001-08-20

    By using a continuous-wave Ti:sapphire laser as a pumping source, we demonstrated a passively Q-switched Yb:YAG laser at room temperature with Cr(4+):YAG as the saturable absorber. We achieved an average output power of as much as 55 mW at 1.03 mum with a pulse width (FWHM) as short as 350 ns. The initial transmission of the Cr(4+):YAG has an effect on the pulse duration (FWHM) and the repetition rate of the Yb:YAG passively Q-switched laser. The Yb:YAG crystal can be a most promising passively Q-switched laser crystal for compact, efficient, solid-state lasers.

  19. Study of microwave magnetoimpedance effect in amorphous FeSiB wires

    NASA Astrophysics Data System (ADS)

    Britel, M. R.; Garcia, C.; Ciureanu, P.; Gauthier, J.; Akyel, C.; Gonzalez, J.; Yelon, A.

    2007-09-01

    Measurements of microwave magnetoimpedance of melt-extracted Fe-rich amorphous wires are presented. These wires were simultaneously submitted to a microwave electromagnetic wave propagating at the wire surface, Joule heating and circumferential static magnetic field. This field is generated by a DC electric current flowing through the wire with maximum strength of 90 mA in order not to reach the recrystallization temperature of the amorphous alloy. The impedance was measured up to 6 GHz using a technique based on the s-parameters measurement of a custom-designed coaxial line by means of a vectorial network analyzer. The real part of the impedance spectra we obtained show peaks, which characterize the magnetic losses occurring in the amorphous material. These peaks shift toward lower frequency for stronger DC currents. Theoretically, these results can be accounted for by the fact that the peaks frequency represents the ferromagnetic resonance occurring in the magnetic material. Its magnitude depends on the saturation magnetization. Since this magnetization decreases with temperature following the Curie law, the resonance frequency also decreases and the impedance peaks shift towards lower frequency.

  20. A Comparative Analysis of Caries Inhibitory Effect of Remineralizing Agents on Human Enamel Treated With Er:YAG Laser: An In-vitro Atomic Emission Spectrometry Analysis

    PubMed Central

    Nair, Aswin Saseendran; Kumar, R Krishna; Ahameed, Syed Shaheed; Punnathara, Sairaj; Peter, Joby

    2016-01-01

    Introduction The tug of war to maintain tooth integrity is dependent on a ratio between demineralization and remineralization. Hence, demineralization should be retarded and remineralization should be enhanced to maintain a natural equilibrium in the oral cavity. Aim To compare in-vitro acid resistance of human enamel when using Casein Phosphopeptides Amorphous Calcium Phosphate (CPP-ACP) [GC Tooth mousse] cream, Casein Phosphopeptide Amorphous Calcium Fluoride Phosphate (CPP-ACFP) [GC Tooth mousse plus] cream, Er:YAG laser alone, combination of CPP-ACP with Er:YAG laser, CPP-ACFP with Er:YAG laser. Materials and Methods An in-vitro study was done on 100 specimens which were prepared from 50 human premolars to investigate the caries inhibitory effect of remineralizing agents and laser on enamel using an atomic emission spectrometry analysis. The enamel specimens were randomly allocated into 6 groups: Untreated (control); CPP-ACP (GC Tooth mousse); CPP-ACFP (GC Tooth mousse plus); Er:YAG laser treatment alone; CPP-ACP with Er:YAG laser; CPP-ACFP with Er: YAG laser. Then specimens were immersed individually in 5ml of acetate buffer solution (0.1mol/L, pH 4.5) and incubated at 37°C for 24 hours, to determine the acid resistance by analyzing the calcium release using atomic emission spectrometry. An ANOVA model was constructed (p-value 0.05), followed by post-hoc Tukey’s test for multiple pair wise comparisons of mean values. Results There was a significant difference among the various groups with respect to amount of calcium released (p<0.001). The lowest mean score of calcium release was observed for CPP-ACFP with Er:YAG laser followed by CPP-ACFP but the differences between these groups were statistically not significant (p>0.05). Similarly the differences between CPP-ACP with Er:YAG laser and CPP-ACP also were not significant (p>0.05). The highest mean score of calcium release was for Er:YAG laser and no significant statistical difference was noticed in

  1. Formation of amorphous materials

    DOEpatents

    Johnson, William L.; Schwarz, Ricardo B.

    1986-01-01

    Metastable amorphous or fine crystalline materials are formed by solid state reactions by diffusion of a metallic component into a solid compound or by diffusion of a gas into an intermetallic compound. The invention can be practiced on layers of metals deposited on an amorphous substrate or by intermixing powders with nucleating seed granules. All that is required is that the diffusion of the first component into the second component be much faster than the self-diffusion of the first component. The method is practiced at a temperature below the temperature at which the amorphous phase transforms into one or more crystalline phases and near or below the temperature at which the ratio of the rate of diffusion of the first component to the rate of self-diffusion is at least 10.sup.4. This anomalous diffusion criteria is found in many binary, tertiary and higher ordered systems of alloys and appears to be found in all alloy systems that form amorphous materials by rapid quenching. The method of the invention can totally convert much larger dimensional materials to amorphous materials in practical periods of several hours or less.

  2. Structural Amorphous Steels

    NASA Astrophysics Data System (ADS)

    Lu, Z. P.; Liu, C. T.; Thompson, J. R.; Porter, W. D.

    2004-06-01

    Recent advancement in bulk metallic glasses, whose properties are usually superior to their crystalline counterparts, has stimulated great interest in fabricating bulk amorphous steels. While a great deal of effort has been devoted to this field, the fabrication of structural amorphous steels with large cross sections has remained an alchemist’s dream because of the limited glass-forming ability (GFA) of these materials. Here we report the discovery of structural amorphous steels that can be cast into glasses with large cross-section sizes using conventional drop-casting methods. These new steels showed interesting physical, magnetic, and mechanical properties, along with high thermal stability. The underlying mechanisms for the superior GFA of these materials are discussed.

  3. Luminescent and scintillation properties of YAG:Tm and YAG:Ce,Tm single crystalline films

    NASA Astrophysics Data System (ADS)

    Zorenko, Yu.; Gorbenko, V.; Savchyn, V.; Suchocki, A.; Wrzesinski, H.; Walczyk, K.; Fabisiak, K.; Bilski, P.; Twardak, A.

    2014-08-01

    The paper is dedicated to studying the luminescent and scintillation properties of the single crystalline films (SCF) of Tm and Tm-Ce doped Y3Al5O12 garnets grown by the liquid phase epitaxy method. We have found that the effective Tm → Ce energy transfer is observed in YAG:Ce,Tm SCF. As a result of such transfer, the scintillation light yield of YAG:Ce,Tm SCF under α-particles excitation can be large in comparison with YAG:Ce SCF counterpart.

  4. Amorphous silicon photovoltaic devices

    DOEpatents

    Carlson, David E.; Lin, Guang H.; Ganguly, Gautam

    2004-08-31

    This invention is a photovoltaic device comprising an intrinsic or i-layer of amorphous silicon and where the photovoltaic device is more efficient at converting light energy to electric energy at high operating temperatures than at low operating temperatures. The photovoltaic devices of this invention are suitable for use in high temperature operating environments.

  5. Disorder-induced amorphization

    SciTech Connect

    Lam, N.Q.; Okamoto, P.R.; Li, Mo

    1997-03-01

    Many crystalline materials undergo a crystalline-to-amorphous (c-a) phase transition when subjected to energetic particle irradiation at low temperatures. By focusing on the mean-square static atomic displacement as a generic measure of chemical and topological disorder, we are led quite naturally to a generalized version of the Lindemann melting criterion as a conceptual framework for a unified thermodynamic approach to solid-state amorphizing transformations. In its simplest form, the generalized Lindemann criterion assumes that the sum of the static and dynamic mean-square atomic displacements is constant along the polymorphous melting curve so that c-a transformations can be understood simply as melting of a critically-disordered crystal at temperatures below the glass transition temperature where the supercooled liquid can persist indefinitely in a configurationally-frozen state. Evidence in support of the generalized Lindemann melting criterion for amorphization is provided by a large variety of experimental observations and by molecular dynamics simulations of heat-induced melting and of defect-induced amorphization of intermetallic compounds.

  6. Amorphous semiconductor solar cell

    DOEpatents

    Dalal, Vikram L.

    1981-01-01

    A solar cell comprising a back electrical contact, amorphous silicon semiconductor base and junction layers and a top electrical contact includes in its manufacture the step of heat treating the physical junction between the base layer and junction layer to diffuse the dopant species at the physical junction into the base layer.

  7. Nd:YAG laser welding aluminum alloys

    SciTech Connect

    Jimenez, E. Jr.

    1992-02-01

    Autogenous Nd:YAG laser welding wrought 4047, 1100, 3003, 2219, 5052, 5086, 5456, and 6061 and cast A356 aluminum alloys to cast A356 aluminum alloy in restrained annular weld joints was investigated. The welds were 12.7 mm (0.375 in.) and 9.5 mm (0.375 in.) diameter with approximately 0.30 mm (0.012 in.) penetration. This investigation determined 4047 aluminum alloy to be the optimum alloy for autogenous Nd:YAG laser welding to cast A356 aluminum alloy. This report describes the investigation and its results.

  8. Microchip laser based on Yb:YAG/V:YAG monolith crystal

    NASA Astrophysics Data System (ADS)

    Nejezchleb, Karel; Šulc, Jan; Jelínková, Helena; Škoda, Václav

    2016-03-01

    V:YAG crystal was investigated as a passive Q-switch of longitudinally diode-pumped microchip laser, emitting radiation at wavelength 1030.5 nm. This laser was based on diffusion bonded monolith crystal (diameter 3 mm) which combines in one piece an active laser part (Yb:YAG crystal, 10 at.% Yb/Y, 3 mm long) and saturable absorber (V:YAG crystal, 2 mm long, initial transmission 86 % @ 1031 nm). The microchip resonator consisted of dielectric mirrors directly deposited on the monolith surfaces (pump mirror HT @ 968 nm and HR @ 1031 nm on Yb:YAG part, output coupler with reflection 55 % @ 1031 nm on the V:YAG part). For longitudinal CW pumping of Yb:YAG part, a fibre coupled (core diameter 100 μm, NA = 0.22, emission @ 968 nm) laser diode was used. The laser threshold was 3.8W. The laser slope efficiency for output mean in respect to incident pumping was 16 %. The linearly polarized generated transversal intensity beam profile was close to the fundamental Gaussian mode. The generated pulse length, stable and mostly independent on pumping power, was equal to 1.3 ns (FWHM). The single pulse energy was increasing with the pumping power and for the maximum pumping 9.7W it was 78 μJ which corresponds to the pulse peak-power 56 kW. The maximum Yb:YAG/V:YAG microchip laser mean output power of 1W was reached without observable thermal roll-over. The corresponding Q-switched pulses repetition rate was 13.1 kHz.

  9. Thin-disk laser based on an Yb:YAG / YAG composite active element

    SciTech Connect

    Kuznetsov, I I; Mukhin, I B; Vadimova, O L; Palashov, O V

    2015-03-31

    A thin-disk laser module based on an Yb:YAG / YAG composite active element is developed with a small-signal gain of 1.25 and a stored energy of 400 mJ under cw pumping. The gain and thermally induced phase distortions in the module are studied experimentally. Based on this module, a thin-disk laser with an average power of 300 W and a slope efficiency of 42% is designed. (lasers)

  10. Stone Retropulsion with Ho: YAG and Tm: YAG Lasers: A Clinical Practice-Oriented Experimental Study.

    PubMed

    Kamal, Wissam; Kallidonis, Panagiotis; Koukiou, Georgia; Amanatides, Lefteris; Panagopoulos, Vasileios; Ntasiotis, Pantelis; Liatsikos, Evangelos

    2016-11-01

    To compare the retropulsion of stones with the use of holmium: yttrium aluminum garnet (Ho: YAG) laser and thulium: yttrium aluminum garnet (Tm: YAG) laser in settings that could be used in clinical practice. The experimental configuration included a glass tube set in a water bath filled with physiologic saline. Plaster of Paris stones were inserted in the tube. Tm: YAG and Ho: YAG laser systems were used along with a high-speed slow-motion camera. The lasers were activated with different settings. The displacement of the stone was measured according to a custom-made algorithm. Ho: YAG: the retropulsion of stones was the lowest with the energy setting of 0.5 J and the frequency of 20 Hz with long pulse duration. The highest retropulsion was observed in the case of 3 J, 5 Hz, and short pulse. Tm: YAG: the retropulsion of stones was the lowest with the energy setting of 1 J and the frequency of 10 Hz with either long or short pulse duration. Practically, there was no retropulsion at all. The highest retropulsion was observed in the case of 8 J, 5 Hz, and short pulse. Ho: YAG laser has a linear increase in stone retropulsion with increased pulse energy. On the other hand, the retropulsion rate was kept to the minimum with Tm: YAG as much as the energy level of 8 J. The activation of lasers with short pulse resulted in further displacement of the stone. Lower frequency with the same power setting seemed to result in further stone retropulsion. Higher power with the same frequency setting resulted in further displacement of the stone.

  11. Erbium:YAG laser for cataract extraction

    NASA Astrophysics Data System (ADS)

    Snyder, Robert W.; Jani, Mahendra G.; Yarborough, Mike; Marcellino, George R.; Noecker, Robert J.; Kramer, Theresa R.; Vidaurri, Jesus

    1998-06-01

    The Erbium:YAG laser may be an effective laser for use in cataract surgery. At 2.94 mm the energy is maximally absorbed by water thereby efficiently disrupting tissue with minimal surrounding thermal damage. The laser may be safer to use in the eye than conventional ultrasonic emulsifiers. Preliminary clinical studies of the safety and efficacy have begun.

  12. Amorphous metallic foam

    NASA Astrophysics Data System (ADS)

    Schroers, Jan; Veazey, Chris; Johnson, William L.

    2003-01-01

    The bulk glass forming alloy Pd43Ni10Cu27P20 is processed into a low-density amorphous metallic foam. Pd43Ni10Cu27P20 is mixed with hydrated B2O3, which releases gas at elevated temperature and/or low pressure. Very homogeneous foams are achieved due to the high viscosity of the alloy even at its liquidus temperature. By processing at the liquidus temperature and decreasing the pressure to 10-2 mbar, well-distributed bubbles expand to foam the material. Foam densities as low as 1.4×103 kg/m3 were obtained, corresponding to a bubble volume fraction of 84%. The bubble diameter ranges between 2×10-4 and 1×10-3 m. Thermal analysis by differential scanning calorimetry confirms the amorphous nature of the foam. Furthermore, it reveals that the foam's thermal stability is comparable to the bulk material.

  13. Amorphous silicon radiation detectors

    DOEpatents

    Street, Robert A.; Perez-Mendez, Victor; Kaplan, Selig N.

    1992-01-01

    Hydrogenated amorphous silicon radiation detector devices having enhanced signal are disclosed. Specifically provided are transversely oriented electrode layers and layered detector configurations of amorphous silicon, the structure of which allow high electric fields upon application of a bias thereby beneficially resulting in a reduction in noise from contact injection and an increase in signal including avalanche multiplication and gain of the signal produced by incoming high energy radiation. These enhanced radiation sensitive devices can be used as measuring and detection means for visible light, low energy photons and high energy ionizing particles such as electrons, x-rays, alpha particles, beta particles and gamma radiation. Particular utility of the device is disclosed for precision powder crystallography and biological identification.

  14. Amorphous silicon radiation detectors

    DOEpatents

    Street, R.A.; Perez-Mendez, V.; Kaplan, S.N.

    1992-11-17

    Hydrogenated amorphous silicon radiation detector devices having enhanced signal are disclosed. Specifically provided are transversely oriented electrode layers and layered detector configurations of amorphous silicon, the structure of which allow high electric fields upon application of a bias thereby beneficially resulting in a reduction in noise from contact injection and an increase in signal including avalanche multiplication and gain of the signal produced by incoming high energy radiation. These enhanced radiation sensitive devices can be used as measuring and detection means for visible light, low energy photons and high energy ionizing particles such as electrons, x-rays, alpha particles, beta particles and gamma radiation. Particular utility of the device is disclosed for precision powder crystallography and biological identification. 13 figs.

  15. Defects in Amorphous Metals.

    DTIC Science & Technology

    1982-07-01

    this map with a similar plot of the experimental data. An experimental deformation data map for Pd-based amorphous al- loys is shown in fig. 10. In the...Masumoto. I Mat. Sci. 12 (1977) 1927, [IgI T M Ha.es. J. W Allen. J. Tauc . B. C. Giessen and J. J. Hauser. Phys. Re. Lett. 41 i197s) 1282 [191 J

  16. A protected annealing strategy to enhanced light emission and photostability of YAG:Ce nanoparticle-based films

    SciTech Connect

    Revaux, Amelie; Dantelle, Geraldine; George, Nathan; Seshadri, Ram; Gacoin, Thierry; Boilot, Jean-Pierre

    2012-03-14

    A significant obstacle in the development of YAG:Ce nanoparticles as light converters in white LEDs and as biological labels is associated with the difficulty of finding preparative conditions that allow simultaneous control of structure, particle size and size distribution, while maintaining the optical properties of bulk samples. Preparation conditions frequently involve high-temperature treatments of precursors (up to 1400 C), which result in increased particle size and aggregation, and lead to oxidation of Ce(III) to Ce(IV). We report here a process that we term protected annealing, that allows the thermal treatment of preformed precursor particles at temperatures up to 1000 C while preserving their small size and state of dispersion. In a first step, pristine nanoparticles are prepared by a glycothermal reaction, leading to a mixture of YAG and boehmite crystalline phases. The preformed nanoparticles are then dispersed in a porous silica. Annealing of the composite material at 1000 C is followed by dissolution of the amorphous silica by hydrofluoric acid to recover the annealed particles as a colloidal dispersion. This simple process allows completion of YAG crystallization while preserving their small size. The redox state of Ce ions can be controlled through the annealing atmosphere. The obtained particles of YAG:Ce (60 {+-} 10 nm in size) can be dispersed as nearly transparent aqueous suspensions, with a luminescence quantum yield of 60%. Transparent YAG:Ce nanoparticle-based films of micron thickness can be deposited on glass substrates using aerosol spraying. Films formed from particles prepared by the protected annealing strategy display significantly improved photostability over particles that have not been subject to such annealing.

  17. A protected annealing strategy to enhanced light emission and photostability of YAG:Ce nanoparticle-based films.

    PubMed

    Revaux, Amelie; Dantelle, Geraldine; George, Nathan; Seshadri, Ram; Gacoin, Thierry; Boilot, Jean-Pierre

    2011-05-01

    A significant obstacle in the development of YAG:Ce nanoparticles as light converters in white LEDs and as biological labels is associated with the difficulty of finding preparative conditions that allow simultaneous control of structure, particle size and size distribution, while maintaining the optical properties of bulk samples. Preparation conditions frequently involve high-temperature treatments of precursors (up to 1400 °C), which result in increased particle size and aggregation, and lead to oxidation of Ce(iii) to Ce(iv). We report here a process that we term protected annealing, that allows the thermal treatment of preformed precursor particles at temperatures up to 1000 °C while preserving their small size and state of dispersion. In a first step, pristine nanoparticles are prepared by a glycothermal reaction, leading to a mixture of YAG and boehmite crystalline phases. The preformed nanoparticles are then dispersed in a porous silica. Annealing of the composite material at 1000 °C is followed by dissolution of the amorphous silica by hydrofluoric acid to recover the annealed particles as a colloidal dispersion. This simple process allows completion of YAG crystallization while preserving their small size. The redox state of Ce ions can be controlled through the annealing atmosphere. The obtained particles of YAG:Ce (60 ± 10 nm in size) can be dispersed as nearly transparent aqueous suspensions, with a luminescence quantum yield of 60%. Transparent YAG:Ce nanoparticle-based films of micron thickness can be deposited on glass substrates using aerosol spraying. Films formed from particles prepared by the protected annealing strategy display significantly improved photostability over particles that have not been subject to such annealing.

  18. CO2, ER:YAG AND ND:YAG LASERS IN ENDODONTIC SURGERY

    PubMed Central

    Pozza, Daniel Humberto; Fregapani, Patrícia Wehmeyer; Xavier, Cristina Braga; Weber, João Batista Blessmann; de Oliveira, Marília Gerhardt

    2009-01-01

    Objectives: CO2, Er:YAG and Nd:YAG lasers have been used in endodontic surgery. This in vitro study evaluated 1% Rhodamine B dye penetration using computer-assisted morphometry (ImageTool Software®) of 108 endodontically treated human permanent canines. Material and methods: Teeth were divided into 9 groups according to the technique used: A: 90-degree apicoectomy with bur, root-end cavity preparation with ultrasound and filled with MTA; B: 90-degree apicoectomy with bur, root-end cavity prepared with ultrasound and filled with MTA, and treatment of apical surface with CO2 laser (1 W, CW/CW); C: 90-degree apicoectomy with bur, and treatment of apical surface with Nd:YAG laser (150 mJ, 10 Hz); D: 90-degree apicoectomy with bur, and treatment of apical surface with CO2 laser (1 W, CW/CW); E: apicoectomy with Er:YAG laser (400 mJ, 10 Hz), root-end cavity prepared with ultrasound and filled with MTA; F: apicoectomy with Er:YAG laser (400 mJ, 10 Hz) and treatment of apical surface with Nd:YAG laser (150 mJ, 10Hz); G: apicoectomy with CO2 laser (5W, CW/SP), root-end cavity prepared with ultrasound and filled with MTA; H: irradiation of apical end with CO2 laser (1 W, CW/CW); I: irradiation of apical end with Nd:YAG laser (150 mJ, 10 Hz). Results: Dye penetration was found in all specimens at different rates, the lowest penetration occurring in groups C (16.20%), B (17.24%) and F (17.84%). Conclusions: Groups B, C and F represent the best technical sequences to perform endodontic surgery. PMID:20027433

  19. CO(2), Er: YAG and Nd:YAG lasers in endodontic surgery.

    PubMed

    Pozza, Daniel Humberto; Fregapani, Patrícia Wehmeyer; Xavier, Cristina Braga; Weber, João Batista Blessmann; Oliveira, Marília Gerhardt de

    2009-01-01

    CO(2), Er:YAG and Nd:YAG lasers have been used in endodontic surgery. This in vitro study evaluated 1% Rhodamine B dye penetration using computer-assisted morphometry (ImageTool Software) of 108 endodontically treated human permanent canines. Teeth were divided into 9 groups according to the technique used: A: 90-degree apicoectomy with bur, root-end cavity preparation with ultrasound and filled with MTA; B: 90-degree apicoectomy with bur, root-end cavity prepared with ultrasound and filled with MTA, and treatment of apical surface with CO(2) laser (1 W, CW/CW); C: 90-degree apicoectomy with bur, and treatment of apical surface with Nd:YAG laser (150 mJ, 10 Hz); D: 90-degree apicoectomy with bur, and treatment of apical surface with CO(2) laser,(1 W, CW/CW); E: apicoectomy with Er:YAG laser (400 mJ, 10 Hz), root-end cavity prepared with ultrasound and filled with MTA; F: apicoectomy with Er:YAG laser (400 mJ, 10 Hz) and treatment of apical surface with Nd:YAG laser (150 mJ, 10Hz); G: apicoectomy with CO(2) laser (5W, CW/SP), root-end cavity prepared with ultrasound and filled with MTA; H: irradiation of apical end with CO(2) laser (1 W, CW/CW); I: irradiation of apical end with Nd:YAG laser (150 mJ, 10 Hz). Dye penetration was found in all specimens at different rates, the lowest penetration occurring in groups C (16.20%), B (17.24%) and F (17.84%). Groups B, C and F represent the best technical sequences to perform endodontic surgery.

  20. Influence of temperature on Yb:YAG/Cr:YAG microchip laser operation

    NASA Astrophysics Data System (ADS)

    Šulc, Jan; Eisenschreiber, Jan; Jelínková, Helena; Nejezchleb, Karel; Å koda, Václav

    2017-02-01

    The goal of this work was an investigation of the temperature influence (in range from 80 up to 320 K) on the laser properties of Yb:YAG/Cr:YAG Q-switched diode-pumped microchip laser. This laser was based on monolith crystal (diameter 3mm) which combines in one piece an active laser part (Yb:YAG crystal, 10 at.% Yb/Y, 3mm long) and saturable absorber (Cr:YAG crystal, 1.36mm long, initial transmission 90% @ 1031 nm). The laser resonator pump mirror (HT for pump radiation, HR for generated radiation) was directly deposited on the Yb:YAG monolith part. The output coupler with reflection 55% for the generated wavelength was placed on the Cr:YAG part. The microchip laser was placed in the temperature controlled cupreous holder inside vacuum chamber of the liquid nitrogen cryostat. For Yb:YAG part longitudinal pulsed pumping (pumping pulse length 2.5 ms, rep-rate 20 Hz, power amplitude 21W) a fibre coupled (core diameter 400 μm, NA= 0:22) laser diode, operating at wavelength 933 nm, was used. The microchip laser mean output power, pulse duration, repetition rate, emission wavelength, and laser beam profile were measured in dependence on temperature. The generated pulse length was in range from 2.2 ns to 1.1 ns (FWHM) with the minimum at 230 K. The single pulse energy was peaking (0.4 mJ) at 180 K. The highest peak power (325 kW) was obtained at 220 K. The highest pulse repetition rate (38 kHz) and output mean power (370mW) was reached for temperature 80 K.

  1. The Stabilization of Amorphous Zopiclone in an Amorphous Solid Dispersion.

    PubMed

    Milne, Marnus; Liebenberg, Wilna; Aucamp, Marique

    2015-10-01

    Zopiclone is a poorly soluble psychotherapeutic agent. The aim of this study was to prepare and characterize an amorphous form of zopiclone as well as the characterization and performance of a stable amorphous solid dispersion. The amorphous form was prepared by the well-known method of quench-cooling of the melt. The solid dispersion was prepared by a solvent evaporation method of zopiclone, polyvinylpyrrolidone-25 (PVP-25), and methanol, followed by freeze-drying. The physico-chemical properties and stability of amorphous zopiclone and the solid dispersion was studied using differential scanning calorimetry (DSC), infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), hot-stage microscopy (HSM), X-ray diffractometry (XRD), solubility, and dissolution studies. The zopiclone amorphous solid-state form was determined to be a fragile glass; it was concluded that the stability of the amorphous form is influenced by both temperature and water. Exposure of amorphous zopiclone to moisture results in rapid transformation of the amorphous form to the crystalline dihydrated form. In comparison, the amorphous solid dispersion proved to be more stable with increased aqueous solubility.

  2. Synthesis of quenchable amorphous diamond

    DOE PAGES

    Zeng, Zhidan; Yang, Liuxiang; Zeng, Qiaoshi; ...

    2017-08-22

    Diamond owes its unique mechanical, thermal, optical, electrical, chemical, and biocompatible materials properties to its complete sp3-carbon network bonding. Crystallinity is another major controlling factor for materials properties. Although other Group-14 elements silicon and germanium have complementary crystalline and amorphous forms consisting of purely sp3 bonds, purely sp3-bonded tetrahedral amorphous carbon has not yet been obtained. In this letter, we combine high pressure and in situ laser heating techniques to convert glassy carbon into “quenchable amorphous diamond”, and recover it to ambient conditions. Our X-ray diffraction, high-resolution transmission electron microscopy and electron energy-loss spectroscopy experiments on the recovered sample andmore » computer simulations confirm its tetrahedral amorphous structure and complete sp3 bonding. This transparent quenchable amorphous diamond has, to our knowledge, the highest density among amorphous carbon materials, and shows incompressibility comparable to crystalline diamond.« less

  3. Hydrogenated Amorphous Silicon

    NASA Astrophysics Data System (ADS)

    Street, R. A.

    1991-08-01

    Divided roughly into two parts, the book describes the physical properties and device applications of hydrogenated amorphous silicon. The first section is concerned with the atomic and electronic structure, and covers growth defects and doping and defect reactions. The emphasis is on the optical and electronic properties that result from the disordered structure. The second part of the book describes electronic conduction, recombination, interfaces, and multilayers. The special attribute of a-Si:H which makes it useful is the ability to deposit the material inexpensively over large areas, while retaining good semiconducting properties, and the final chapter discusses various applications and devices.

  4. Holmium:YAG laser stapedotomy: preliminary evaluation

    NASA Astrophysics Data System (ADS)

    Stubig, Ingrid M.; Reder, Paul A.; Facer, G. W.; Rylander, Henry G.; Welch, Ashley J.

    1993-07-01

    This study investigated the use of a pulsed Holmium:YAG ((lambda) equals 2.09 micrometers ) laser- fiber microsurgical system for laser stapedotomy. This system ablates human stapes bones effectively with minimal thermal damage. The study was designed to determine the effectiveness of the Ho:YAG laser (Schwartz Electro Optics, Inc., Orlando, FL) for stapedotomy and to evaluate temperature changes within the cochlea during the ablation process. Human cadaveric temporal bones were obtained and the stapes portion of the ossicular chain was removed. A 200 micrometers diameter low OH quartz fiber was used to irradiate these stapes bones in an air environment. The laser was pulsed at 2 Hz, 250 microsecond(s) ec pulse width and an irradiance range of 100 - 240 J/cm2 was used to ablate holes in the stapes footplate. The resultant stapedotomies created had smooth 300 micrometers diameter holes with a minimum of circumferential charring. Animal studies in-vivo were carried out in chinchillas to determine the caloric spread within the cochlea. A 0.075 mm Type T thermocouple was placed in the round window. Average temperature change during irradiation of the stapes footplate recorded in the round window was 3.6 degree(s)C. The data suggest that stapedotomy using the Ho:YAG laser can result in a controlled ablation of the stapes footplate with minimal thermal damage to the surrounding stapes. Optical coupling using fiberoptic silica fibers is an ideal method for delivering laser energy to the stapes during stapedotomy.

  5. High-Power COIL and YAG Laser Welding

    DTIC Science & Technology

    2002-01-24

    UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADP012387 TITLE: High-Power COIL and YAG Laser Welding DISTRIBUTION...ADP012376 thru ADP012405 UNCLASSIFIED High-power COIL and YAG laser welding Fumio Wani, Tokuhiro Nakabayashi, Akiyoshi Hayakawa, Sachio Suzuki, and...is worse, but it has the function of pulse modulation which the COIL dose not have. As a result of the welding test with the 6 kW Nd:YAG laser, it

  6. Optically triggered Cr:YAG Q-switched Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Cole, Brian; Hays, Alan; Lei, Jonathan; Schilling, Bradley; Goldberg, Lew

    2011-02-01

    The method of optical triggering using a brass board architecture for a Q-switched Nd:YAG laser by direct bleaching of a Cr:YAG saturable absorber was determined to be effective in reducing the pulse-to-pulse timing jitter. A miniaturized triggering setup was employed to enable the brass board operation of the optically triggered laser. A 3mm wide minilaser diode bar (1024nm) with collimated emission was mounted on a compact heat sink and used to bleach the Cr:YAG saturable absorber from a direction orthogonal to the lasing axis. A compact 300A pulse driver, with <0.5 μs rise time and 3-5 μs duration, was developed for pulsing the 3mm diode bar. These components were combined to demonstrate a compact brassboard implementation of the optically triggered passively Q-switched laser.

  7. Cervical microleakage in root canals treated with Er:YAG and Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Sponchiado, Emilio C., Jr.; Azevedo, Lidiany K.; Marchesan, Melissa; Brugnera, Aldo, Jr.; Silva-Sousa, Yara T.; Alfredo, Edson; Sousa Neto, Manoel D.

    2005-03-01

    Cervical microleakage was evaluated in sealed root canals previously treated with Er:YAG and Nd:YAG lasers. Ninety-two single-rooted maxillary human canines were prepared with the crown-down technique and irrigated with distilled and deionized water. The samples were distributed randomly into 9 groups of 10 teeth each. One tooth was used as a positive control and one as a negative control. In group I, 1.2 ml of EDTAC was applied during 5 min. In groups II to V, radicular dentine was irradiated with Er:YAG laser (Opus 20, Opus Dent, Israel) at the following parameters: 200 mJ and 8 Hz, 200 mJ and 16 Hz, 400 mJ and 8 Hz, or 400 mJ and 16Hz, respectively, for 60 s. In groups VI to IX, radicular dentine was irradiated with Nd:YAG laser (Fotona Medical Lasers, Slovenia) at 10 Hz and 1 W, 10 Hz and 2 W, 15 Hz and 1 W, or 15 Hz and 2 W, respectively, for 60 s. The canals were then sealed by the lateral condensation technique with an epoxy resin-based sealer. The roots were immersed in India ink for 15 days and then cleared to visualize the level of cervical microleakage with a measurement microscope. The results were evaluated by the Kruskal-Wallis test, which showed no statistical significance (p>0.01) for parameter variations of the Er:YAG laser when compared to the control group. However, the increase in frequency and potency for Nd:YAG laser decreased the microleakage when compared to the control group.

  8. Ho:YAG laser application in cerebellopontine angle tumor operation

    NASA Astrophysics Data System (ADS)

    Pan, Yaohua; Wang, Yu; Li, Xiaoxiong; Xiong, Xiong; Wang, Yong-ling; Li, Shanquan; Luo, Qizhong; Zhu, Jing; Zhang, Weiguo

    2005-07-01

    We reported 25 cases of cerebellopontine angle (CPA) tumor operation with Ho:YAG laser assistance during the operative procedure. We analysed the surgical effects of Ho:YAG laser, compare it with CO2 Nd:YAG argon laser, and illustrated its features and parameters. We think that Ho:YAG laser can be used to ablate and vaporize the tumor efficiently in the operation of the CPA tumors whose vascular supply is abundant and the texture is very tough. It can be used to reduce the bleeding and cooperate to incise tumor in the operation and improve the curable effect of the surgery.

  9. Laboratory and clinical experience with neodymium:YAG laser prostatectomy

    NASA Astrophysics Data System (ADS)

    Kabalin, John N.

    1996-05-01

    Since 1991, we have undertaken extensive laboratory and clinical studies of the Neodymium:YAG (Nd:YAG) laser for surgical treatment of bladder outlet obstruction due to prostatic enlargement or benign prostatic hyperplasia (BPH). Side-firing optical fibers which emit a divergent, relatively low energy density Nd:YAG laser beam produce coagulation necrosis of obstructing periurethral prostate tissue, followed by gradual dissolution and slough in the urinary stream. Laser-tissue interactions and Nd:YAG laser dosimetry for prostatectomy have been studied in canine and human prostate model systems, enhancing clinical application. Ongoing studies examine comparative Nd:YAG laser dosimetry for various beam configurations produced by available side-firing optical fibers and continue to refine operative technique. We have documented clinical outcomes of Nd:YAG laser prostatectomy in 230 consecutive patients treated with the UrolaseTM side-firing optical fiber. Nd:YAG laser coagulation the prostate produces a remarkably low acute morbidity profile, with no significant bleeding or fluid absorption. No postoperative incontinence has been produced. Serial assessments of voiding outcomes over more than 3 years of followup show objective and symptomatic improvement following Nd:YAG laser prostatectomy which is comparable to older but more morbid electrosurgical approaches. Nd:YAG laser prostatectomy is a safe, efficacious, durable and cost-effective treatment for BPH.

  10. High peak-power passively Q-switched all-ceramics Nd:YAG/Cr4+:YAG lasers

    NASA Astrophysics Data System (ADS)

    Pavel, Nicolaie; Tsunekane, Masaki; Taira, Takunori

    2010-05-01

    The output performances of a compact, passively Q-switched Nd:YAG/Cr4+:YAG laser were investigated using single crystals and poli-crystalline ceramics Nd:YAG with doping level between 1.0 and 2.0-at.% Nd, and single crystals and poli-crystalline ceramics Cr4+:YAG with various initial transmission. Q-switch laser pulses at 1.06 μm with energies up to 2 mJ and duration below 1 ns were realized at a pump repetition rate of 10 Hz. An all-ceramics Nd:YAG/Cr4+:YAG laser could be a solution for ignition of automotive engines. The optical intensity of a laser pulse with ns duration that induces optical air breakdown was determined.

  11. High peak-power passively Q-switched all-ceramics Nd:YAG/Cr4+:YAG lasers

    NASA Astrophysics Data System (ADS)

    Pavel, Nicolaie; Tsunekane, Masaki; Taira, Takunori

    2009-09-01

    The output performances of a compact, passively Q-switched Nd:YAG/Cr4+:YAG laser were investigated using single crystals and poli-crystalline ceramics Nd:YAG with doping level between 1.0 and 2.0-at.% Nd, and single crystals and poli-crystalline ceramics Cr4+:YAG with various initial transmission. Q-switch laser pulses at 1.06 μm with energies up to 2 mJ and duration below 1 ns were realized at a pump repetition rate of 10 Hz. An all-ceramics Nd:YAG/Cr4+:YAG laser could be a solution for ignition of automotive engines. The optical intensity of a laser pulse with ns duration that induces optical air breakdown was determined.

  12. Diffraction losses of Nd:YAG and Yb:YAG laser crystals

    NASA Astrophysics Data System (ADS)

    Xie, Wenjie; Kwon, Young; Tam, Siu-Chung; Lam, Yee-Loy

    2001-03-01

    Based on space-dependent rate equations, the lowest threshold input power for a diode end-pumped solid-state laser is obtained for the pump spot size wp→0. However, as the pump beam waist is decreased, the thermally induced effects in the laser rod would be very high. Diffraction losses caused by radial and tangential variations of refractive index have been analyzed and compared for the Nd : YAG and the Yb : YAG at room temperature ( 300 K) and liquid-nitrogen temperature ( 77 K).

  13. Crystal growth induced by Nd:YAG laser irradiation in patterning glass ceramic substrates with dots

    NASA Astrophysics Data System (ADS)

    Sola, D.; Escartín, A.; Cases, R.; Peña, J. I.

    2011-03-01

    In this work a glass ceramic substrate was processed by focusing a laser beam inside the said material. The crystal phase within the amorphous matrix provides mechanical properties to the glass ceramic substrate in such a way that dots can be patterned inside the fore-mentioned material without producing any cracks. These marks are made up of crystals, the growth of which has been induced by the laser beam. These inner structures can modify the optical, thermal and mechanical properties of the glass ceramic substrate. A Q-switched Nd:YAG laser at its fundamental wavelength of 1064 nm with pulsewidths in the nanosecond range has been used. Morphology, composition, microstructure, mechanical and thermal properties of the processed material are described.

  14. Apical sealing quality of in vitro apicectomy procedures after using both Er:YAG and Nd:YAG.

    PubMed

    Leonardi, Denise Piotto; Sivieri-Araujo, Gustavo; Zielak, Joao Cesar; Baratto-Filho, Flares; Moriyama, Lilian Tan; Berbert, Fabio Luiz Camargo Villela

    2010-10-01

    The aim of this study was to evaluate the apical sealing of dentinal tubules after root-end surface cutting by using Er:YAG and Nd:YAG lasers. After root-canal instrumentation and filling, apices of 50 extracted maxillary canine human teeth were resected by Er:YAG with 400 mJ, 10 Hz, for 30 sec. The samples were randomly assigned to five groups (n = 10): (GI) treated without root-end cavity, but with Nd:YAG (1.0 W, 10 Hz, 20 sec) for dentinal tubules sealing; (GII) treated with root-end cavity without the use of Nd:YAG; (GIII) treated with root-end cavity and Nd:YAG application; (GIV) treated with root-end cavity made by Er:YAG with no focus and without Nd:YAG application; and (GV) treated without root-end cavity and without Nd:YAG application. The root-end cavities were performed by using Er:YAG at 300 mJ, 10 Hz, for 20 sec. Subsequently, all teeth were waterproofed and immersed in 2% methylene blue for 48 h in a vacuum environment. The samples were longitudinally sectioned, and microleakage was measured. ANOVA and the Fisher LSD test showed that GIV was less susceptible to microleakage than were the other groups (p < 0.05). Interestingly, the use of the Er:YAG with no focus showed superior dentinal tubule sealing in comparison with the other groups, even with or without root-end cavity and Nd:YAG application.

  15. Investigations of YAG:Er(3+),Yb(3+) and YAG:Co(2+) Crystals for Laser Applications

    DTIC Science & Technology

    2001-01-01

    doped YAG crystals are given. Erbium and ytterbium doped YAG single crystals were obtained by the Czochralski method . The spectral properties and laser...relaxation time of 290 Rts14 2. CRYSTAL GROWTH The crystals were obtained by the Czochralski method , using iridium crucibles of external dimensions...YAG:Co 2+ single crystal grown by Czochralski method is presented. In all obtained crystals the core area of the characteristic threefold symmetry was

  16. High-efficiency lasing and spectroscopy of domestic 1%Nd:YAG and 1%Ho:YAG ceramics

    NASA Astrophysics Data System (ADS)

    Vatnik, S. M.; Vedin, I. A.; Kurbatov, P. F.; Osipov, V. V.; Luk'yashin, K. E.; Maksimov, R. N.; Solomonov, V. I.

    2017-01-01

    We report on spectroscopy and high-efficiency lasing of YAG ceramics synthesized at the Institute of Electrophysics, Ural Branch, Russian Academy of Sciences. The best slope efficiency is to be 36% for 1%Nd:YAG ceramics and 40% for 1%Ho:YAG ceramics, in the latter case the emission was centred at 2090 nm. Internal losses in the samples of domestic ceramics were estimated.

  17. Compensated amorphous silicon solar cell

    DOEpatents

    Carlson, David E.

    1980-01-01

    An amorphous silicon solar cell incorporates a region of intrinsic hydrogenated amorphous silicon fabricated by a glow discharge wherein said intrinsic region is compensated by P-type dopants in an amount sufficient to reduce the space charge density of said region under illumination to about zero.

  18. Amorphous silicon ionizing particle detectors

    DOEpatents

    Street, Robert A.; Mendez, Victor P.; Kaplan, Selig N.

    1988-01-01

    Amorphous silicon ionizing particle detectors having a hydrogenated amorphous silicon (a--Si:H) thin film deposited via plasma assisted chemical vapor deposition techniques are utilized to detect the presence, position and counting of high energy ionizing particles, such as electrons, x-rays, alpha particles, beta particles and gamma radiation.

  19. Amorphous silicon ionizing particle detectors

    DOEpatents

    Street, R.A.; Mendez, V.P.; Kaplan, S.N.

    1988-11-15

    Amorphous silicon ionizing particle detectors having a hydrogenated amorphous silicon (a--Si:H) thin film deposited via plasma assisted chemical vapor deposition techniques are utilized to detect the presence, position and counting of high energy ionizing particles, such as electrons, x-rays, alpha particles, beta particles and gamma radiation. 15 figs.

  20. Compensated amorphous silicon solar cell

    DOEpatents

    Devaud, Genevieve

    1983-01-01

    An amorphous silicon solar cell including an electrically conductive substrate, a layer of glow discharge deposited hydrogenated amorphous silicon over said substrate and having regions of differing conductivity with at least one region of intrinsic hydrogenated amorphous silicon. The layer of hydrogenated amorphous silicon has opposed first and second major surfaces where the first major surface contacts the electrically conductive substrate and an electrode for electrically contacting the second major surface. The intrinsic hydrogenated amorphous silicon region is deposited in a glow discharge with an atmosphere which includes not less than about 0.02 atom percent mono-atomic boron. An improved N.I.P. solar cell is disclosed using a BF.sub.3 doped intrinsic layer.

  1. Intrinsic and Ce 3+-related luminescence of YAG and YAG:Ce single crystals, single crystalline films and nanopowders

    NASA Astrophysics Data System (ADS)

    Zorenko, Yu.; Zych, E.; Voloshinovskii, A.

    2009-10-01

    A comparative analysis of the luminescent properties of YAG and YAG:Ce nanopowders (NP) in comparison with single crystalline film (SCF) and single crystal (SC) analogues was performed under excitation by a pulsed synchrotron and X-ray radiation. It was shown that the natural defects concentration in NP was between the SC with a large (˜0.18-0.19 at.%) concentration of Y Al antisite defects (AD) and SCF of these garnets where Y Al AD were completely absent. At the same time, Ce 3+ doped YAG NP showed luminescent properties close to those of YAG:Ce SCF.

  2. YAG Laser Vitreolysis vs Sham YAG Vitreolysis for Symptomatic Vitreous Floaters: A Randomized Clinical Trial.

    PubMed

    Shah, Chirag P; Heier, Jeffrey S

    2017-09-01

    Vitreous floaters are common and can worsen visual quality. YAG vitreolysis is an untested treatment for floaters. To evaluate YAG laser vitreolysis vs sham vitreolysis for symptomatic Weiss ring floaters from posterior vitreous detachment. This single-center, masked, sham-controlled randomized clinical trial was performed from March 25, 2015, to August 3, 2016, in 52 eyes of 52 patients (36 cases and 16 controls) treated at a private ophthalmology practice. Patients were randomly assigned to YAG laser vitreolysis or sham YAG (control). Primary 6-month outcomes were subjective change measured from 0% to 100% using a 10-point visual disturbance score, a 5-level qualitative scale, and National Eye Institute Visual Functioning Questionnaire 25 (NEI VFQ-25). Secondary outcomes included objective change assessed by masked grading of color fundus photography and Early Treatment Diabetic Retinopathy Study best-corrected visual acuity. Fifty-two patients (52 eyes; 17 men and 35 women; 51 white and 1 Asian) with symptomatic Weiss rings were enrolled in the study (mean [SD] age, 61.4 [8.0] years for the YAG laser group and 61.1 [6.6] years for the sham group). The YAG laser group reported greater symptomatic improvement (54%) than controls (9%) (difference, 45%; 95% CI, 25%-64%; P < .001). In the YAG laser group, the 10-point visual disturbance score improved by 3.2 vs 0.1 in the sham group (difference, -3.0; 95% CI, -4.3 to -1.7; P < .001). A total of 19 patients (53%) in the YAG laser group reported significantly or completely improved symptoms vs 0 individuals in the sham group (difference, 53%; 95% CI, 36%-69%, P < .001). Compared with sham, NEI VFQ-25 revealed improved general vision (difference, 16.3; 95% CI, 0.9-31.7; P = .04), peripheral vision (difference, 11.6; 95% CI, 0.8-22.4; P = .04), role difficulties (difference, 17.3; 95% CI, 8.0-26.6; P < .001), and dependency (difference, 5.6; 95% CI, 0.5-10.8; P = .03) among the YAG laser group

  3. Bulk amorphous materials

    SciTech Connect

    Schwarz, R.B.; Archuleta, J.I.; Sickafus, K.E.

    1998-12-01

    This is the final report for a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this work was to develop the competency for the synthesis of novel bulk amorphous alloys. The authors researched their synthesis methods and alloy properties, including thermal stability, mechanical, and transport properties. The project also addressed the development of vanadium-spinel alloys for structural applications in hostile environments, the measurement of elastic constants and thermal expansion in single-crystal TiAl from 300 to 750 K, the measurement of elastic constants in gallium nitride, and a study of the shock-induced martensitic transformations in NiTi alloys.

  4. The possibility of clinical application of the solid state lasers: Nd:YAG, Ho:YAG, and Er:YAG in otolaryngology - head and neck surgery

    NASA Astrophysics Data System (ADS)

    Tomaszewska, M.; Kukwa, A.; Tulibacki, M.; Wójtowicz, P.; Olędzka, I.; Jeżewska, E.

    2007-02-01

    The purpose of this study was to summarize our experiences in clinical application of Nd:YAG, Ho:YAG and Er:YAG in otolaryngology- head and neck surgery. Choosing the laser type and parameters for the particular procedures was based on our previous research on tissue effects of those lasers. During the period of 1993-2006 we performed 3988 surgical procedures with the Nd:YAG laser. Over 87% of those were made for the nasal cavity pathologies as polyps, hyperplasia of inferior nasal turbinate, granulation tissue, postoperative adhesions, vascular malformations, under the local anesthesia conditions. In our experience Nd:YAG laser gives the possibility of good clinical control and low risk of side effects for disorders of high recurrence and frequent interventions necessity, as nasal polyps or respiratory papillomatosis. Nd:YAG assisted uvulopalatoplasty gives an interesting alternative for surgical procedures for snoring and slight/mild OSA-recognized patients. Due to its good hemostatic properties, it is a perfect tool for removal of the chemodectoma from meddle ear. During the period of 1995-2006 we performed 229 surgical procedures with the Ho:YAG laser, mostly for larynx pathologies (adhesion and scar tissue removal). In our experience Ho:YAG laser can serve as a precise laser knife for both soft and bony tissue. The ER:YAG laser still remain under clinical trial. Since 2001 year we performed 24 procedures of removing stone deposits from salivary glands. We believe it may become a promising method to cope with sialolithiasis which allows for glandule function preservation. All of the laser types mentioned above, can be easily coupled with endoscopes, what makes them available for all of the head and necklocalized disorders.

  5. Use of the holmium:YAG laser in coronary disease

    NASA Astrophysics Data System (ADS)

    Heuser, Richard R.

    1992-08-01

    The holmium:YAG laser, a new solid-state, infrared laser system, is being used increasingly more often for treating peripheral vascular disease. We discuss the early use of this device in coronary laser angioplasty. The holmium:YAG laser has several advantages over excimer systems and may prove to be an effective adjunctive to coronary balloon angioplasty.

  6. Nanosecond cryogenic Yb:YAG disk laser

    SciTech Connect

    Perevezentsev, E A; Mukhin, I B; Kuznetsov, I I; Vadimova, O L; Palashov, O V

    2014-05-30

    A cryogenic Yb:YAG disk laser is modernised to increase its average and peak power. The master oscillator unit of the laser is considerably modified so that the pulse duration decreases to several nanoseconds with the same pulse energy. A cryogenic disk laser head with a flow-through cooling system is developed. Based on two such laser heads, a new main amplifier is assembled according to an active multipass cell scheme. The total small-signal gain of cryogenic cascades is ∼10{sup 8}. (lasers)

  7. [Treatment of tracheobronchial lesions with Laser Yag].

    PubMed

    Dumon, J F; Reboud, E; Auconte, F; Sacco, E; Meric, B

    1981-10-13

    Various tracheobronchial obstruction indications have been treated with laser yag neodyme with flexible fibre introduced into a bronchofibroscope. Experience covers 44 patients who underwent 75 photocoagulation sessions under local or general anaesthesia. Inoperable tracheo-bronchial tumours are the most frequent and spectacular indications. Malignant tumour, cylindromas, carcinomas and benign tumours are the best indications. Tracheal stenoses were treated in association with instrumental dilatation. The other indications proposed are resections of granulomas, resection of suture threads, extraction of peripheral foreign bodies and control of major haemorrhages. No complications were observed. The immediate effectiveness of this new technique is considerable. Long-term development depends on the aetiology of tracheobronchial stenosis.

  8. Containerless processing of amorphous ceramics

    NASA Technical Reports Server (NTRS)

    Weber, J. K. Richard; Krishnan, Shankar; Schiffman, Robert A.; Nordine, Paul C.

    1990-01-01

    The absence of gravity allows containerless processing of materials which could not otherwise be processed. High melting point, hard materials such as borides, nitrides, and refractory metals are usually brittle in their crystalline form. The absence of dislocations in amorphous materials frequently endows them with flexibility and toughness. Systematic studies of the properties of many amorphous materials have not been carried out. The requirements for their production is that they can be processed in a controlled way without container interaction. Containerless processing in microgravity could permit the control necessary to produce amorphous forms of hard materials.

  9. Apatite Formation from Amorphous Calcium Phosphate and Mixed Amorphous Calcium Phosphate/Amorphous Calcium Carbonate.

    PubMed

    Ibsen, Casper J S; Chernyshov, Dmitry; Birkedal, Henrik

    2016-08-22

    Crystallization from amorphous phases is an emerging pathway for making advanced materials. Biology has made use of amorphous precursor phases for eons and used them to produce structures with remarkable properties. Herein, we show how the design of the amorphous phase greatly influences the nanocrystals formed therefrom. We investigate the transformation of mixed amorphous calcium phosphate/amorphous calcium carbonate phases into bone-like nanocrystalline apatite using in situ synchrotron X-ray diffraction and IR spectroscopy. The speciation of phosphate was controlled by pH to favor HPO4 (2-) . In a carbonate free system, the reaction produces anisotropic apatite crystallites with large aspect ratios. The first formed crystallites are highly calcium deficient and hydrogen phosphate rich, consistent with thin octacalcium phosphate (OCP)-like needles. During growth, the crystallites become increasingly stoichiometric, which indicates that the crystallites grow through addition of near-stoichiometric apatite to the OCP-like initial crystals through a process that involves either crystallite fusion/aggregation or Ostwald ripening. The mixed amorphous phases were found to be more stable against phase transformations, hence, the crystallization was inhibited. The resulting crystallites were smaller and less anisotropic. This is rationalized by the idea that a local phosphate-depletion zone formed around the growing crystal until it was surrounded by amorphous calcium carbonate, which stopped the crystallization. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Fabrication of amorphous diamond films

    DOEpatents

    Falabella, S.

    1995-12-12

    Amorphous diamond films having a significant reduction in intrinsic stress are prepared by biasing a substrate to be coated and depositing carbon ions thereon under controlled temperature conditions. 1 fig.

  11. Amorphous and Ultradisperse Crystalline Materials,

    DTIC Science & Technology

    The book sums up experimental and theoretical findings on amorphous and ultradisperse crystalline materials , massive and film types. Present-day... crystalline materials of metallic systems are presented. Emphasis is placed on inorganic film materials.

  12. Nd: YAG photodisruptors. American Academy of Ophthalmology

    SciTech Connect

    Not Available

    1989-09-01

    Nd: YAG laser surgery can cut lens capsule, vitreous and capsular membranes, strands, and adhesions, and the iris within the surgically unopened eye, thereby avoiding infection, wound leaks, and other complications of conventional intraocular surgery. The technique has found its most widespread use in performing posterior capsulotomies after extracapsular cataract surgery. It has an extremely low complication rate when used in the anterior segment and is a preferred alternative to surgical discission. The uncertainties regarding its safety in creating iridotomies in phakic eyes have lessened with its extensive use in patients with pupillary-block glaucoma. However, caution is urged in other applications in phakic eyes. Following each Nd: YAG laser procedure, the eye should be monitored for elevation of intraocular pressure during the first two hours, and for retinal tears, retinal detachment, or cystoid macular edema during the first month after the procedure. Uncertainties persist regarding the circumstances under which the laser in its current configuration should be used in the vitreous cavity.

  13. Diode pumped Nd:YAG laser development

    NASA Technical Reports Server (NTRS)

    Reno, C. W.; Herzog, D. G.

    1976-01-01

    A low power Nd:YAG laser was constructed which employs GaAs injection lasers as a pump source. Power outputs of 125 mW TEM CW with the rod at 250 K and the pump at 180 K were achieved for 45 W input power to the pump source. Operation of the laser, with array and laser at a common heat sink temperature of 250 K, was inhibited by difficulties in constructing long-life GaAs LOC laser arrays. Tests verified pumping with output power of 20 to 30 mW with rod and pump at 250 K. Although life tests with single LOC GaAs diodes were somewhat encouraging (with single diodes operating as long as 9000 hours without degradation), failures of single diodes in arrays continue to occur, and 50 percent power is lost in a few hundred hours at 1 percent duty factor. Because of the large recent advances in the state of the art of CW room temperature AlGaAs diodes, their demonstrated lifetimes of greater than 5,000 hours, and their inherent advantages for this task, it is recommended that these sources be used for further CW YAG injection laser pumping work.

  14. Characterization Techniques for Amorphous Alloys

    NASA Astrophysics Data System (ADS)

    Carow-Watamura, U.; Louzguine, D. V.; Takeuchi, A.

    This document is part of Part 2 http://dx.doi.org/10.1007/9getType="URL"/> 'Systems from B-Be-Fe to Co-W-Zr' of Subvolume B 'Physical Properties of Ternary Amorphous Alloys' of Volume 37 'Phase Diagrams and Physical Properties of Nonequilibrium Alloys' of Landolt-Börnstein - Group III 'Condensed Matter'. It contains the Chapter '2 Characterization Techniques for Amorphous Alloys' with the content:

  15. Amorphous metal alloy and composite

    DOEpatents

    Wang, Rong; Merz, Martin D.

    1985-01-01

    Amorphous metal alloys of the iron-chromium and nickel-chromium type have excellent corrosion resistance and high temperature stability and are suitable for use as a protective coating on less corrosion resistant substrates. The alloys are stabilized in the amorphous state by one or more elements of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The alloy is preferably prepared by sputter deposition.

  16. Combined effect of fluoride varnish to Er:YAG or Nd:YAG laser on permeability of eroded root dentine.

    PubMed

    Chiga, Sandra; Toro, Carmen Victoria Torres; Lepri, Taísa Penazzo; Turssi, Cecília Petroso; Colucci, Vivian; Corona, Silmara Aparecida Milori

    2016-04-01

    This study evaluated the combined effect of fluoride varnish to Er:YAG or Nd:YAG laser on permeability of eroded root dentine. Sixty slabs of bovine root dentine (2×2×2mm) were eroded with citric acid 0.3% (pH 3.2) during 2h and then kept in artificial saliva during 24h. Specimens were randomly assigned in 6 groups (n=10), to receive the following treatments: fluoride varnish; fluoride varnish+Er:YAG laser; fluoride varnish+Nd:YAG laser; non-fluoride varnish; non-fluoride varnish+Er:YAG laser; non-fluoride varnish+Nd:YAG laser. The Er:YAG (100mJ, 3Hz) and Nd:YAG (70mJ, 15Hz) were applied for 10s. Specimens were subjected to further erosive challenges with citric acid 0.3% 4×/day, during 1min, for 5 days, remaining in artificial saliva between cycles. Dentin permeability was then assessed. Two-way ANOVA demonstrated no significant interaction between laser and varnish (p=0.858). No effect was also detected for the main factor varnish (p=0.768), while permeability of eroded root dentin was significantly lower when such substrate was laser-irradiated, no matter the laser source (p<0.001). This study concluded that Er:YAG and Nd:YAG lasers can be employed to control the permeability of eroded root dentin, regardless of fluoride varnish application. Copyright © 2016. Published by Elsevier Ltd.

  17. Evaluation of Er:YAG, CO2, and Nd:YAG lasers on apical dentine permeability after apicoectomies

    NASA Astrophysics Data System (ADS)

    Careli de Castro, Fabiana; Gariba Silva, Ricardo; Marchesan, Melissa A.; Zanin, Fatima; Brugnera, Aldo, Jr.; Pecora, Jesus D.

    2004-05-01

    Apicoectomy is a surgical procedure that consists of radicular apex resection, eliminating periapical lesion. This study evaluated the effect of CO2 and Nd:YAG lasers on root dentine permeability after apicoectomy with Er:YAG laser. Forty-four single-rooted teeth, obtained from the Endodontic Laboratory stock from the Faculty of Dentistry of Ribeirao Preto, University of Sao Paulo, were used. The teeth were instrumented with the step-back technique, irrigated with 1.0% sodium hypochlorite and sealed with Sealer 26 (Dentsply, Brazil; lateral condensation. The samples were divided into four groups of 11 teeth each that had the root sectioned 2mm from the apex: G1 - roots were sectioned with a 4138 diamond bur with cooling; G2 - roots were sectioned with pulsed Er:YAG laser at the following parameters: 15 Hz and 250 mJ; G3 - roots were sectioned with pulsed Er:YAG laser and Nd:YAG laser (10 Hz, 100 mJ, and 1 W) was app0lied on the sectioned surface; G4 - roots were sectioned with pulsed Er:YAG laser and CO2 laser (5 W, 10 seconds ON and 20 seconds OFF) was applied to the sectioned surface. The teeth were then impermeabilized with cyanoacrylate and placed in 0.5% methylene blue for 7 days. The proximal surface of the samples was removed for exposure of the sealed root canal and dye penetration was measured by means of microscopic evaluation. The results showed a statistically significant difference at the level of 1%. We conclude that all treatments presented microleakage and can placed in increasing order: Er:YAG (G2), Bur (G1), Er:YAG + Nd:YAG (G3); Er:YAG laser presented the lowest microleakage values, showing its viability for clinical use in apicoectomies.

  18. 21 CFR 886.4392 - Nd:YAG laser for posterior capsulotomy and peripheral iridotomy.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Nd:YAG laser for posterior capsulotomy and...:YAG laser for posterior capsulotomy and peripheral iridotomy. (a) Identification. The Nd:YAG laser for... laser intended for disruption of the posterior capsule or the iris via optical breakdown. The Nd:YAG...

  19. 21 CFR 886.4392 - Nd:YAG laser for posterior capsulotomy and peripheral iridotomy.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Nd:YAG laser for posterior capsulotomy and...:YAG laser for posterior capsulotomy and peripheral iridotomy. (a) Identification. The Nd:YAG laser for... laser intended for disruption of the posterior capsule or the iris via optical breakdown. The Nd:YAG...

  20. 21 CFR 886.4392 - Nd:YAG laser for posterior capsulotomy and peripheral iridotomy.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Nd:YAG laser for posterior capsulotomy and...:YAG laser for posterior capsulotomy and peripheral iridotomy. (a) Identification. The Nd:YAG laser for... laser intended for disruption of the posterior capsule or the iris via optical breakdown. The Nd:YAG...

  1. 21 CFR 886.4392 - Nd:YAG laser for posterior capsulotomy and peripheral iridotomy.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nd:YAG laser for posterior capsulotomy and...:YAG laser for posterior capsulotomy and peripheral iridotomy. (a) Identification. The Nd:YAG laser for... laser intended for disruption of the posterior capsule or the iris via optical breakdown. The Nd:YAG...

  2. 21 CFR 886.4392 - Nd:YAG laser for posterior capsulotomy and peripheral iridotomy.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Nd:YAG laser for posterior capsulotomy and...:YAG laser for posterior capsulotomy and peripheral iridotomy. (a) Identification. The Nd:YAG laser for... laser intended for disruption of the posterior capsule or the iris via optical breakdown. The Nd:YAG...

  3. Ablation of porcine ligamentum flavum with Ho:YAG, q-switched Ho:YAG, and quadrupled Nd:YAG lasers.

    PubMed

    Johnson, Matt R; Codd, Patrick J; Hill, Westin M; Boettcher, Tara

    2015-12-01

    Ligamentum flavum (LF) is a tough, rubbery connective tissue providing a portion of the ligamentous stability to the spinal column, and in its hypertrophied state forms a significant compressive pathology in degenerative spinal stenosis. The interaction of lasers and this biological tissue have not been thoroughly studied. Technological advances improving endoscopic surgical access to the spinal canal makes selective removal of LF using small, flexible tools such as laser-coupled fiber optics increasingly attractive for treatment of debilitating spinal stenosis. Testing was performed to assess the effect of Ho:YAG, Q-switched Ho:YAG, and frequency quadrupled Nd:YAG lasers on samples of porcine LF. The objective was to evaluate the suitability of these lasers for surgical removal of LF. LF was resected from porcine spine within 2 hours of sacrifice and stored in saline until immediately prior to laser irradiation, which occurred within an additional 2 hours. The optical absorbance of a sample was measured over the spectral band from 190 to 2,360 nm both before and after dehydration. For the experiments using the Ho:YAG (λ = 2,080 nm, tp  = 140 µs, FWHM) and Q-Switched Ho:YAG (λ = 2,080 nm, tp  = 260 ns, FWHM) lasers, energy was delivered to the LF through a laser-fiber optic with 600 µm core and NA = 0.39. For the experiment using the frequency quadrupled Nd:YAG laser (λ = 266 nm, tp  = 5 ns FWHM), rather than applying the laser energy through a laser-fiber, the energy was focused through an aperture and lens directly onto the LF. Five experiments were conducted to evaluate the effect of the given lasers on LF. First, using the Ho:YAG laser, the single-pulse laser-hole depth versus laser fluence was measured with the laser-fiber in direct contact with the LF (1 g force) and with a standoff distance of 1 mm between the laser-fiber face and the LF. Second, with the LF remaining in situ and the spine bisected

  4. Hydrogenated amorphous silicon photonics

    NASA Astrophysics Data System (ADS)

    Narayanan, Karthik

    2011-12-01

    Silicon Photonics is quickly proving to be a suitable interconnect technology for meeting the future goals of on-chip bandwidth and low power requirements. However, it is not clear how silicon photonics will be integrated into CMOS chips, particularly microprocessors. The issue of integrating photonic circuits into electronic IC fabrication processes to achieve maximum flexibility and minimum complexity and cost is an important one. In order to minimize usage of chip real estate, it will be advantageous to integrate in three-dimensions. Hydrogenated amorphous silicon (a-Si:H) is emerging as a promising material for the 3-D integration of silicon photonics for on-chip optical interconnects. In addition, a-Si:H film can be deposited using CMOS compatible low temperature plasma-enhanced chemical vapor deposition (PECVD) process at any point in the fabrication process allowing maximum flexibility and minimal complexity. In this thesis, we demonstrate a-Si:H as a high performance alternate platform to crystalline silicon, enabling backend integration of optical interconnects in a hybrid photonic-electronic network-on-chip architecture. High quality passive devices are fabricated on a low-loss a-Si:H platform enabling wavelength division multiplexing schemes. We demonstrate a broadband all-optical modulation scheme based on free-carrier absorption effect, which can enable compact electro-optic modulators in a-Si:H. Furthermore, we comprehensively characterize the optical nonlinearities in a-Si:H and observe that a-Si:H exhibits enhanced nonlinearities as compared to crystalline silicon. Based on the enhanced nonlinearities, we demonstrate low-power four-wave mixing in a-Si:H waveguides enabling high speed all-optical devices in an a-Si:H platform. Finally, we demonstrate a novel data encoding scheme using thermal and all-optical tuning of silicon waveguides, increasing the spectral efficiency in an interconnect link.

  5. Amorphous carbon for photovoltaics

    NASA Astrophysics Data System (ADS)

    Risplendi, Francesca; Grossman, Jeffrey C.

    2015-03-01

    All-carbon solar cells have attracted attention as candidates for innovative photovoltaic devices. Carbon-based materials such as graphene, carbon nanotubes (CNT) and amorphous carbon (aC) have the potential to present physical properties comparable to those of silicon-based materials with advantages such as low cost and higher thermal stability.In particular a-C structures are promising systems in which both sp2 and sp3 hybridization coordination are present in different proportions depending on the specific density, providing the possibility of tuning their optoelectronic properties and achieving comparable sunlight absorption to aSi. In this work we employ density functional theory to design suitable device architectures, such as bulk heterojunctions (BHJ) or pn junctions, consisting of a-C as the active layer material.Regarding BHJ, we study interfaces between aC and C nanostructures (such as CNT and fullerene) to relate their optoelectronic properties to the stoichiometry of aC. We demonstrate that the energy alignment between the a-C mobility edges and the occupied and unoccupied states of the CNT or C60 can be widely tuned by varying the aC density to obtain a type II interface.To employ aC in pn junctions we analyze the p- and n-type doping of a-C focusingon an evaluation of the Fermi level and work function dependence on doping.Our results highlight promising features of aC as the active layer material of thin-film solar cells.

  6. A tunable corner-pumped Nd:YAG/YAG composite slab CW laser

    NASA Astrophysics Data System (ADS)

    Liu, Huan; Gong, Ma-Li

    2012-10-01

    A corner-pumped Nd:YAG/YAG composite slab continuous-wave laser operating at 1064 nm, 1074 nm, 1112 nm, 1116 nm, and 1123 nm simultaneously and a laser that is tunable at these wavelengths are reported for the first time. The maximum output power of the five-wavelength laser is 5.66 W with an optical-to-optical conversion efficiency of 11.3%. After a birefringent filter is inserted in the cavity, the five wavelengths can be separated successfully by rotating the filter. The maximum output powers of the 1064 nm, 1074 nm, 1112 nm, 1116 nm, and 1123 nm lasers are 1.51 W, 1.3 W, 1.27 W, 0.86 W, and 0.72 W, respectively.

  7. Passively Q-switched Nd:YAG/Cr4+:YAG micro laser with high beam quality

    NASA Astrophysics Data System (ADS)

    Huang, Xuesong; Hui, Yongling; Jiang, Menghua; Lei, Hong; Li, Qiang

    2016-10-01

    Laser diode end-pumped passively Q-switched Nd:YAG/Cr4+:YAG micro lasers, with short pulse width, high repetition rate, high peak power and compact structure, have widely applications in laser mico processing, optical communication, laser radar, medical and other fields. But its beam quality is not excellent because of short resonant cavity, thermal effect of crystal, and pump laser. The beam quality is promoted in this paper by compressing the pump beam size and confirming the best position of pump beam focus in crystal. The repletion rate of laser is 20kHz. The output single pulse energy is 18.2μJ and pulse width is 1.23ns. The beam quality of laser is M2=1.18.

  8. Cathodo- and radioluminescence of Tm 3+ : YAG and Nd 3+ : YAG in an extended wavelength range

    NASA Astrophysics Data System (ADS)

    Borghesani, A. F.; Braggio, C.; Carugno, G.; Chiossi, F.; Guarise, M.

    2017-10-01

    We have studied the cathodo- and radioluminescence of Nd:YAG and of Tm:YAG single crystals in an extended wavelength range up to $\\approx 5\\,\\mu$m in view of developing a new kind of detector for low-energy, low-rate energy deposition events. Whereas the light yield in the visible range is as large as $\\approx 10^{4}\\,$photons/MeV, in good agreement with literature results, in the infrared range we have found a light yield $\\approx 5\\times 10^{4}\\,$photons/MeV, thereby proving that ionizing radiation is particularly efficient in populating the low lying levels of rare earth doped crystals.

  9. High-power YAG laser and its applications

    NASA Astrophysics Data System (ADS)

    Sato, S.; Tsuchiya, Kazuyuki; Owaki, Katsura; Morita, Ichiro

    2000-02-01

    Laser beams have been noticed as new heat resources with high energy concentration, which are different from plasma and arc. Conventionally, the only kW class industrial laser has been a carbon dioxide (CO2) laser. However, recently, several new high power lasers other than CO2 laser have been developed so that new methods of laser material processing have come out. As for YAG lasers, formerly, cw or pulse YAG lasers of several hundreds W class were used for welding or cutting of electrical appliants or cutting of thin metal plates. Now, the power has been raised to 5 - 6 kW, which enables YAG lasers to apply wider applications of material processing in many industrial fields, such as automobile industries, heavy industries and so on. It is a flexible fiber delivery that is the most remarkable advantage of YAG laser, which can be applied to ordinary machinery tools and robotic systems and makes it possible to deliver laser power to remote locations. Moreover, a shorter wavelength (1.06 micrometer) of YAG lasers than that of CO2 lasers is appropriate to metal processing. Figure 1 shows an example of YAG laser processing system utilizing those advantages. Also in IHI, the processing with YAG lasers has been studied for their practical application which has already succeeded in some sections such as cladding, repair welding and subdividing of nuclear power plants making use of YAG lasers' properties of fiber delivery of beam. Moreover, underwater processing technique is studied for practical use. In this paper, the examples of YAG laser application technology were described.

  10. Influence of temperature on Nd:YAG/V:YAG compact laser generation at 1444 nm

    NASA Astrophysics Data System (ADS)

    Šulc, Jan; Novák, Jakub; Jelínková, Helena; Nejezchleb, Karel; Škoda, Václav

    2010-02-01

    Compact Q-switched diode-pumped laser, emitting radiation at eye-safe wavelength 1444 nm, was studied. This laser was based on composite crystal (diameter 5mm) consisting of 4mm long Nd:YAG active medium diffusion bonded with 1mm long V:YAG saturable absorber (initial transmission @ 1444nm 94 %). The laser resonator mirrors were directly deposited onto the composite crystal surfaces. These mirrors were designed to ensure emission at 1444nm and to prevent parasitic lasing at other Nd3+ transmissions. The pump mirror (R < 10% for pump radiation @ 808 nm, R < 2% @ 1064 nm, R < 15% @ 1330 nm, HR @ 1444 nm) was placed on the Nd3+-doped YAG part. The output coupler with reflectivity 94% for the generated wavelength 1444nm was placed on the V3+-doped part (R < 5% @ 1064 nm, R < 15% @ 1330 nm). Temperature dependence of giant pulse energy and length was studied independently on pumping pulses duty cycle. It was found that for constant duty cycle 1% and for crystal holder temperature rise from 8.2 up to 43.2 °C the pulse width dropped from 31 to 5.1 ns and pulse energy rose from 17 to 57 μJ. This represents a pulse peak power increase from 0.54 up to 11kW. From a mathematical model of passively Q-switched laser it follows that this behaviour can be explained by temperature caused increase of ground-state absorption and ground-state to excited-state absorption ratio (FOM) of V:YAG saturable absorber at wavelength 1444nm in case if FOM ~ 1.

  11. Stimulated Raman adiabatic passage in Tm{sup 3+}:YAG

    SciTech Connect

    Alexander, A. L.; Lauro, R.; Louchet, A.; Chaneliere, T.; Le Goueet, J. L.

    2008-10-01

    We report on the experimental demonstration of stimulated Raman adiabatic passage in a Tm{sup 3+}:YAG crystal. Tm{sup 3+}:YAG is a promising material for use in quantum information processing applications, but as yet there are few experimental investigations of coherent Raman processes in this material. We investigate the effect of inhomogeneous broadening and Rabi frequency on the transfer efficiency and the width of the two-photon spectrum. Simulations of the complete Tm{sup 3+}:YAG system are presented along with the corresponding experimental results.

  12. Operation of Ho:YAG ultrafast laser inscribed waveguide lasers.

    PubMed

    McDaniel, Sean; Thorburn, Fiona; Lancaster, Adam; Stites, Ronald; Cook, Gary; Kar, Ajoy

    2017-04-20

    We report fabrication and operation of multi-watt level waveguide lasers utilizing holmium-doped yttrium aluminum garnet (Ho:YAG). The waveguides were fabricated using ultrafast laser inscription, which relies on a chirped pulse ytterbium fiber laser to create depressed cladding structures inside the material. A variety of waveguides were created inside the Ho:YAG samples. We demonstrate output powers of ∼2  W from both a single-mode 50 μm waveguide laser and a multimode 80 μm waveguide laser. In addition, laser action from a co-doped Yb:Ho:YAG sample under in-band pumping conditions was demonstrated.

  13. Lasing and thermal characteristics of Yb:YAG/YAG composite with atomic diffusion bonding

    NASA Astrophysics Data System (ADS)

    Sankar Nagisetty, Siva; Severova, Patricie; Miura, Taisuke; Smrž, Martin; Kon, Hitoe; Uomoto, Miyuki; Shimatsu, Takehito; Kawasaki, Masato; Higashiguchi, Takeshi; Endo, Akira; Mocek, Tomáš

    2017-01-01

    We demonstrated the laser performance of an Yb:YAG/YAG composite ceramic laser medium mounted on an aluminium heatsink via atomic diffusion bonding (ADB) technique using nanocrystalline metal films at room temperature in air. The surface temperature rise of the ADB bonded laser medium was linear with 57 °C lower than that of the commercially available soldered Yb:YAG thin disk at the pump power of 280 W. Moreover, the ADB disk was pumped 1.5 times higher (7.3 kW cm-2) than the typical damage threshold of the soldered disk without any sign of damage. The undoped capping may be effective for the suppression of ASE heating; however, according to the in situ OPD measurement it induces strong thermal lensing. The CW laser output power of 177 W was obtained at the pump power of 450 W with the optical-to-optical efficiency of 40% using V-shape cavity.

  14. Ion diffusion at the bonding interface of undoped YAG/Yb:YAG composite ceramics

    NASA Astrophysics Data System (ADS)

    Fujioka, Kana; Sugiyama, Akira; Fujimoto, Yasushi; Kawanaka, Junji; Miyanaga, Noriaki

    2015-08-01

    Cation diffusion across a boundary between ytterbium (Yb)-doped and undoped yttrium aluminum garnet (YAG) ceramics was examined by electron microprobe analysis (EPMA). Polished Yb:YAG and undoped YAG ceramics were bonded by surface treatment with argon fast atom beam, and then heat-treated at 1400 or 1600 °C for 50 h or at 1400 °C for 10 h under vacuum. We obtained EPMA mapping images of the bonded samples that clearly showed the bulk and grain-boundary diffusion of Y and Yb ions. The number density profiles showed that the total diffusion distances of Yb and Y ions were almost equal and approximately 2 and 15 μm at 1400 and 1600 °C, respectively, and the dependence of diffusion distance on heating time was weak. The diffusion curves were well modeled by Harrison type B kinetics including bulk and grain-boundary diffusion. In addition, it was found that Si ions added to the samples as a sintering aid might be segregated at the grain boundary by heat treatment, and diffused only along grain boundaries.

  15. Histologic comparison of needle, holmium:YAG, and erbium:YAG endoscopic goniotomy

    NASA Astrophysics Data System (ADS)

    Joos, Karen M.; Shen, Jin-Hui; Rivera, Brian K.; Hernandez, Eleut; Shetlar, Debra J.

    1995-05-01

    An endoscope allows visualization of the anterior chamber angle in porcine eyes despite the presence of cloudy corneas. The pectinate ligaments in the anterior chamber angle are a surgical model for primary infantile glaucoma. This study investigated the histologic results, one month after treating the anterior chamber angle with a goniotomy needle, the holmium:YAG laser, or the erbium:YAG laser coupled to a small endoscope. The anterior chambers were deepened with a viscoelastic material in one-month-old anesthetized pigs. An Olympus 0.8 mm diameter flexible endoscope was externally coupled to a 23 gauge needle or a 300 micron diameter fiber. The angle was treated for 120 degrees by one of the three methods, and the probe was removed. During the acute study, all three methods cut the pectinate ligaments. The histologic findings one month after healing demonstrated minimal surrounding tissue damage following goniotomy with a needle and the most surrounding tissue damage following treatment with the holmium:YAG laser.

  16. Crystallography of Alumina-YAG-Eutectic

    NASA Technical Reports Server (NTRS)

    Farmer, Serene C.; Sayir, Ali; Dickerson, Robert M.; Matson, Lawrence E.

    2000-01-01

    Multiple descriptions of the alumina-YAG eutectic crystallography appear in the ceramic literature. The orientation between two phases in a eutectic system has direct impact on residual stress, morphology, microstructural stability, and high temperature mechanical properties. A study to demonstrate that the different crystallographic relationships can be correlated with different growth constraints was undertaken. Fibers produced by Laser-Heated Float Zone (LHFZ) and Edge-defined Film-fed Growth (EFG) were examined. A map of the orientation relationship between Al2O3 and Y3Al5O12 and their relationship to the fiber growth axis as a function of pull rate are presented. Regions in which a single orientation predominates are identified.

  17. Pulsed Nd-YAG laser in endodontics

    NASA Astrophysics Data System (ADS)

    Ragot-Roy, Brigitte; Severin, Claude; Maquin, Michel

    1994-12-01

    The purpose of this study was to establish an operative method in endodontics. The effect of a pulsed Nd:YAG laser on root canal dentin has been examined with a scanning electron microscope. Our first experimentation was to observe the impacts carried out perpendicularly to root canal surface with a 200 micrometers fiber optic in the presence of dye. Secondarily, the optical fiber was used as an endodontic instrument with black dye. The irradiation was performed after root canal preparation (15/100 file or 40/100 file) or directly into the canal. Adverse effects are observed. The results show that laser irradiation on root canal dentin surfaces induces a nonhomogeneous modified dentin layer, melted and resolidified dentin closed partially dentinal tubules. The removal of debris is not efficient enough. The laser treatment seems to be indicated only for endodontic and periapical spaces sterilization after conventional root canal preparation.

  18. Efficient 1645-nm Er:YAG laser

    NASA Astrophysics Data System (ADS)

    Young, York E.; Setzler, Scott D.; Snell, Kevin J.; Budni, Peter A.; Pollak, Thomas M.; Chicklis, E. P.

    2004-05-01

    We report a resonantly fiber-laser-pumped Er:YAG laser operating at the eye-safe wavelength of 1645 nm, exhibiting 43% optical efficiency and 54% incident slope efficiency and emitting 7-W average power when repetitively Q switched at 10 kHz. To our knowledge, this is the best performance (conversion efficiency and average power) obtained from a bulk solid-state Q-switched erbium laser. At a 1.1-kHz pulse repetition frequency the laser produces 3.4-mJ pulses with a corresponding peak power of 162 kW. Frequency doubling to produce 822.5-nm, 4.7-kW pulses at 10 kHz was performed to demonstrate the laser's utility.

  19. Allotropic composition of amorphous carbon

    SciTech Connect

    Yastrebov, S. G. Ivanov-Omskii, V. I.

    2007-08-15

    Using the concept of an inhomogeneous broadening of spectral lines of the basic oscillators responsible for forming the spectrum, the experimental dependences of the dispersion of the imaginary part of permittivity are analyzed for amorphous carbon. It turned out that four types of oscillators contribute to this dependence. The first three types represent the electron transitions from the energy-spectrum ground state for {pi} and {sigma} electrons of amorphous carbon to an excited state. The fourth type is related to the absorption of electromagnetic radiation by free charge carriers. The absolute values of squared plasma frequencies of oscillators are estimated, and, using them, the relative fraction of sp{sup 2}-bonded atoms forming the amorphous-carbon skeleton is calculated. This estimate agrees closely with the theoretical predictions for amorphous carbon of the same density as the material under study. The dependence of the relative fraction of sp{sup 2}-bonded atoms contained in amorphous hydrogenised carbon on annealing temperature is determined. The developed method is also applied to the analysis of the normalized curve for the light extinction in the interstellar medium. The contribution to the extinction of two varieties of interstellar matter is detected.

  20. NdYag Laser for Acne Keloidalis Nuchae

    ClinicalTrials.gov

    2013-03-27

    Acne Keloidalis Nuchae; NdYag Laser; AKN; Acne Keloidalis; AK; Dermatitis Papillaris Capillitii; Folliculitis Keloidalis Nuchae; Sycosis Nuchae; Acne Keloid; Keloidal Folliculitis; Lichen Keloidalis Nuchae; Folliculitis Nuchae Scleroticans; Sycosis Framboesiformis

  1. Use of the Nd-YAG laser in neurosurgery.

    PubMed

    Beck, O J

    1984-01-01

    After many years of experience, in general we prefer the Nd-YAG laser, although the CO2 laser is an advantage in a few specific cases (lipomas, cranial synostosis). While the focused CO2 laser may be used as a cutting instrument in less vascular tissue with little trauma to the surroundings, the Nd-YAG laser produces a homogeneous coagulation with an energy dependent depth effect. Thus, with the Nd-YAG laser residual tumour tissue can be selectively and with a predictable depth effect thermally destroyed. Because of its excellent coagulation property, the use of the Nd-YAG laser is particularly indicated in highly vascular meningeal tumours. The shrinkage of a tumour and its demarcation which is due to the varying absorption properties facilitates the dissection and allows in addition the preservation of normal tissue.

  2. Neodymium-YAG laser vitreolysis in sickle cell retinopathy

    SciTech Connect

    Hrisomalos, N.F.; Jampol, L.M.; Moriarty, B.J.; Serjeant, G.; Acheson, R.; Goldberg, M.F.

    1987-08-01

    Six patients with proliferative sickle cell retinopathy and vitreous bands were treated with the neodymium-YAG (Nd-YAG) laser to accomplish lysis of avascular traction bands or to clear the media in front of the macula. Transection of bands was possible in five of the six cases but in two of these the effect was only partial. Three cases were satisfactorily treated with the Nd-YAG laser application alone, two eventually required conventional vitreoretinal surgery, and one patient's condition stabilized despite failure of the treatment. Complications from the treatment occurred in three cases and included subretinal (choroidal) hemorrhage, preretinal hemorrhage, microperforation of a retinal vein, and focal areas of damage to the retinal pigment epithelium. Neodymium-YAG vitreolysis may be a useful modality in carefully selected patients with proliferative sickle cell retinopathy, but potentially sight-threatening complications may occur.

  3. Nanostructures having crystalline and amorphous phases

    DOEpatents

    Mao, Samuel S; Chen, Xiaobo

    2015-04-28

    The present invention includes a nanostructure, a method of making thereof, and a method of photocatalysis. In one embodiment, the nanostructure includes a crystalline phase and an amorphous phase in contact with the crystalline phase. Each of the crystalline and amorphous phases has at least one dimension on a nanometer scale. In another embodiment, the nanostructure includes a nanoparticle comprising a crystalline phase and an amorphous phase. The amorphous phase is in a selected amount. In another embodiment, the nanostructure includes crystalline titanium dioxide and amorphous titanium dioxide in contact with the crystalline titanium dioxide. Each of the crystalline and amorphous titanium dioxide has at least one dimension on a nanometer scale.

  4. Universal features of amorphous plasticity

    NASA Astrophysics Data System (ADS)

    Budrikis, Zoe; Castellanos, David Fernandez; Sandfeld, Stefan; Zaiser, Michael; Zapperi, Stefano

    2017-07-01

    Plastic yielding of amorphous solids occurs by power-law distributed deformation avalanches whose universality is still debated. Experiments and molecular dynamics simulations are hampered by limited statistical samples, and although existing stochastic models give precise exponents, they require strong assumptions about fixed deformation directions, at odds with the statistical isotropy of amorphous materials. Here, we introduce a fully tensorial, stochastic mesoscale model for amorphous plasticity that links the statistical physics of plastic yielding to engineering mechanics. It captures the complex shear patterning observed for a wide variety of deformation modes, as well as the avalanche dynamics of plastic flow. Avalanches are described by universal size exponents and scaling functions, avalanche shapes, and local stability distributions, independent of system dimensionality, boundary and loading conditions, and stress state. Our predictions consistently differ from those of mean-field depinning models, providing evidence that plastic yielding is a distinct type of critical phenomenon.

  5. Amorphous-diamond electron emitter

    DOEpatents

    Falabella, Steven

    2001-01-01

    An electron emitter comprising a textured silicon wafer overcoated with a thin (200 .ANG.) layer of nitrogen-doped, amorphous-diamond (a:D-N), which lowers the field below 20 volts/micrometer have been demonstrated using this emitter compared to uncoated or diamond coated emitters wherein the emission is at fields of nearly 60 volts/micrometer. The silicon/nitrogen-doped, amorphous-diamond (Si/a:D-N) emitter may be produced by overcoating a textured silicon wafer with amorphous-diamond (a:D) in a nitrogen atmosphere using a filtered cathodic-arc system. The enhanced performance of the Si/a:D-N emitter lowers the voltages required to the point where field-emission displays are practical. Thus, this emitter can be used, for example, in flat-panel emission displays (FEDs), and cold-cathode vacuum electronics.

  6. Generalized melting criterion for amorphization

    SciTech Connect

    Devanathan, R. |; Lam, N.Q.; Okamoto, P.R.; Meshii, M.

    1992-12-01

    We present a thermodynamic model of solid-state amorphization based on a generalization of the well-known Lindemann criterion. The original Lindemann criterion proposes that melting occurs when the root-mean-square amplitude of thermal displacement exceeds a critical value. This criterion can be generalized to include solid-state amorphization by taking into account the static displacements. In an effort to verify the generalized melting criterion, we have performed molecular dynamics simulations of radiation-induced amorphization in NiZr, NiZr{sub 2}, NiTi and FeTi using embedded-atom potentials. The average shear elastic constant G was calculated as a function of the total mean-square atomic displacement following random atom-exchanges and introduction of Frenkel pairs. Results provide strong support for the generalized melting criterion.

  7. Universal features of amorphous plasticity

    PubMed Central

    Budrikis, Zoe; Castellanos, David Fernandez; Sandfeld, Stefan; Zaiser, Michael; Zapperi, Stefano

    2017-01-01

    Plastic yielding of amorphous solids occurs by power-law distributed deformation avalanches whose universality is still debated. Experiments and molecular dynamics simulations are hampered by limited statistical samples, and although existing stochastic models give precise exponents, they require strong assumptions about fixed deformation directions, at odds with the statistical isotropy of amorphous materials. Here, we introduce a fully tensorial, stochastic mesoscale model for amorphous plasticity that links the statistical physics of plastic yielding to engineering mechanics. It captures the complex shear patterning observed for a wide variety of deformation modes, as well as the avalanche dynamics of plastic flow. Avalanches are described by universal size exponents and scaling functions, avalanche shapes, and local stability distributions, independent of system dimensionality, boundary and loading conditions, and stress state. Our predictions consistently differ from those of mean-field depinning models, providing evidence that plastic yielding is a distinct type of critical phenomenon. PMID:28671191

  8. Universal features of amorphous plasticity.

    PubMed

    Budrikis, Zoe; Castellanos, David Fernandez; Sandfeld, Stefan; Zaiser, Michael; Zapperi, Stefano

    2017-07-03

    Plastic yielding of amorphous solids occurs by power-law distributed deformation avalanches whose universality is still debated. Experiments and molecular dynamics simulations are hampered by limited statistical samples, and although existing stochastic models give precise exponents, they require strong assumptions about fixed deformation directions, at odds with the statistical isotropy of amorphous materials. Here, we introduce a fully tensorial, stochastic mesoscale model for amorphous plasticity that links the statistical physics of plastic yielding to engineering mechanics. It captures the complex shear patterning observed for a wide variety of deformation modes, as well as the avalanche dynamics of plastic flow. Avalanches are described by universal size exponents and scaling functions, avalanche shapes, and local stability distributions, independent of system dimensionality, boundary and loading conditions, and stress state. Our predictions consistently differ from those of mean-field depinning models, providing evidence that plastic yielding is a distinct type of critical phenomenon.

  9. Treatment of patients with OSAS using Nd-YAG laser

    NASA Astrophysics Data System (ADS)

    Kukwa, Andrzej; Tulibacki, Marek P.; Zajac, Andrzej; Dudziec, Katarzyna

    2000-06-01

    The authors present their clinical experience regarding the possibilities of application of Nd:YAG and Ho:YAG lasers for the treatment of disorders in the are of the upper respiratory tract. The patients with symptoms of Obstructive Sleep Aphnoe Syndrom need a various operations techniques. Lasers techniques makes it possible to perform a number of procedures in local anesthesia which considerably improves the economic effectiveness of the treatment. The surgeries performed using laser beam enabled very good effect of treatment.

  10. Application of Yb:YAG short pulse laser system

    DOEpatents

    Erbert, Gaylen V.; Biswal, Subrat; Bartolick, Joseph M.; Stuart, Brent C.; Crane, John K.; Telford, Steve; Perry, Michael D.

    2004-07-06

    A diode pumped, high power (at least 20W), short pulse (up to 2 ps), chirped pulse amplified laser using Yb:YAG as the gain material is employed for material processing. Yb:YAG is used as the gain medium for both a regenerative amplifier and a high power 4-pass amplifier. A single common reflective grating optical device is used to both stretch pulses for amplification purposes and to recompress amplified pulses before being directed to a workpiece.

  11. Ho:YAG Single Crystal Fiber: Fabrication and Optical Characterization

    DTIC Science & Technology

    2014-06-16

    Gabrielyan, V. Fromzel, X. Mu, H. Meissner, and M. Dubinskii, “High efficiency, resonantly diode pumped, double- clad , Er:YAG-core, waveguide laser ,” Opt...technique,” Opt. Express 16(16), 12264–12271 (2008). 14. M. J. F. Digonnet, C. J. Gaeta, D. O’Meara, and H. J. Shaw, “ Clad Nd:YAG fibers for laser ...with smaller diameters and various methods of cladding are currently under investigation for high power laser /amplifier applications. However, these

  12. Erbium:Yag laser therapy of lichenoid red tattoo reaction.

    PubMed

    De Argila, D; Chaves, A; Moreno, J C

    2004-05-01

    Delayed reactions caused by red tattoo pigments are often difficult to treat. We report a 31-year-old female patient with a lichenoid reaction to a red tattoo on the right ankle who was successfully treated with five sessions of a surgical Erbium:Yag laser, using several passes in each session. Our work leads us to consider that Er:Yag laser therapy may be an effective and safe treatment for these therapeutically challenging reactions.

  13. Polarisation dynamics of a Nd:YAG ceramic laser

    SciTech Connect

    Khandokhin, Pavel A; Ievlev, Ivan V; Lebedeva, Yu S; Mukhin, I B; Palashov, O V; Khazanov, Efim A

    2011-02-28

    We report an experimental study of the polarisation dynamics of a dual-polarisation microchip Nd:YAG ceramic laser. Our results demonstrate dual-polarisation operation of the polycrystalline Nd:YAG laser. The low-frequency dynamics in this regime involves three types of relaxation oscillations, two of which are responsible for antiphase dynamics of the intensities of orthogonally polarised modes. Linearly polarised pump light induces gain anisotropy in the Nd:YAG ceramic, as in Nd:YAG single-crystal lasers. We present a comparative analysis of the behaviour of orthogonally polarised modes in Nd:YAG single-crystal lasers and the Nd:YAG ceramic laser, with a random orientation of the crystallographic axes in each grain (microcrystal), describe a technique for evaluating the total cavity loss from the relaxation oscillation spectrum and compare single-crystal and ceramic active elements. Experimental evidence is presented for gain anisotropy, loss anisotropy and phase anisotropy in ceramic and single-crystal microchip lasers. (lasers)

  14. Study on direct laser fabrication of Nd:YAG

    NASA Astrophysics Data System (ADS)

    Chen, Guangxia; Xiong, Zheng; Lu, Yaojun; Zeng, Xiaoyan

    2007-07-01

    Recently, the study on the direct laser fabrication by CO II laser is more than that by Nd: YAG laser. The primary goal of this research is to study technics and structure performance of metal component of laser rapid prototyping based on Nd: YAG laser and coaxial powder feeder. The experimental equipments consist of ROFIN 1.1KW YAG laser, a 3-axis CNC table, a coaxial powder nozzle and a powder recycler. Firstly, the single-track cladding experiment was conducted; the effect of laser power, scan velocity and Z-axis increment on the single-track cladding shape was studied with different processing parameters. Secondly, some tensile samples, which were built by direct laser fabrication (DLF) using the best processing parameters, were analyzed by tensile experiment, SEM and EDS. The effect of Nd: YAG laser rapid prototyping technology on the structure and performance was studied and compared with the results of CO II laser fabrication on the approximate condition. Lastly, some molding samples built by Nd: YAG laser were shown in the paper. In conclusion, the technics parameters have large effect on the molding result; the key technology of laser rapid prototyping is searching the best process parameters. The tensile samples built by Nd: YAG laser have the features of high intensity, fine crystalline grains and orientated solidification structure; moreover, the orientations of laser scanning have influence on tensile performance. Compared with the CO II laser rapid prototyping, its tensile strength is higher and its plasticity is lower.

  15. Photoluminescence properties of thermographic phosphors YAG:Dy and YAG:Dy, Er doped with boron and nitrogen

    NASA Astrophysics Data System (ADS)

    Chepyga, Liudmyla M.; Jovicic, Gordana; Vetter, Andreas; Osvet, Andres; Brabec, Christoph J.; Batentschuk, Miroslaw

    2016-08-01

    This paper investigates Dy3+-doped and Dy3+, Er3+-co-doped yttrium aluminum garnets (YAG) with the admixture of boron nitride with the aim of using them as efficient thermographic phosphors at high temperatures. The phosphors were synthesized using a conventional high-temperature solid-state method. The influence of two fluxes, B2O3 and LiF/NH4F, and the effect of activator and coactivator concentrations were investigated. Additionally, the effect of B3+ and N3- substituting for Al3+ and O2- ions, respectively, in the YAG:Dy3+ co-doped with Er3+ was studied for the first time. The changes in the host lattice led to a much stronger photoluminescence compared with the samples without B3+ and N3- substitution. The admixture of BN also improves the thermal sensitivity of the YAG:Dy and YAG:Dy, Er thermographic phosphors.

  16. Clinical application of the Nd-YAG and Ho-YAG lasers in otolaryngology: head and neck surgery

    NASA Astrophysics Data System (ADS)

    Kukwa, Andrzej; Tulibacki, Marek P.; Dudziec, Katarzyna; Wojtowicz, Piotr

    1997-10-01

    The authors present their clinical experience regarding the possibilities of application of Nd:YAG and Ho:YAG lasers for the treatment of disorders in the area of the upper respiratory tract sinuses and ears. This technique makes it possible to perform a number of procedures in local anesthesia which considerably improves the economic effectiveness of the treatment. In case of the Nd:YAG laser they have also utilized the effect of deep coagulation of the soft tissues, whereas the Ho:YAG laser energy was applied for the surgery of bone tissue. The surgeries performed using laser beam enabled very good effect of treatment. They are competitive compared wit the methods used by traditional surgery.

  17. Suppression of parasitic oscillations in a core-doped ceramic Nd:YAG laser by Sm:YAG cladding.

    PubMed

    Huss, Rafael; Wilhelm, Ralf; Kolleck, Christian; Neumann, Jörg; Kracht, Dietmar

    2010-06-07

    The onset of parasitic oscillations limits the extraction efficiency and therefore energy scaling of Q-switched lasers. A solid-state laser was end pumped with a fiber-coupled diode laser and operated in q-cw as well as in passively Q-switched operation. For Q-switched operation, we demonstrate the suppression of parasitic oscillations in a core-doped ceramic Nd:YAG laser by Sm:YAG cladding.

  18. Ultrastable Amorphous Sb2Se3 Film.

    PubMed

    Zhang, Kai; Li, Yang; Huang, Quan; Wang, Bihan; Zheng, Xuerong; Ren, Yang; Yang, Wenge

    2017-08-31

    Increasing the thermostability of amorphous materials has been a long journey to improve their properties. The metastable nature of chalcogenide glasses limits their practical applications as an amorphous semiconductor in photovoltaic performance. Here, we report the formation and physical properties of ultrastable amorphous Sb2Se3 with an enhanced thermal stability compared to ordinary amorphous Sb2Se3 (ΔTx= 17 K). By in situ high temperature-high energy synchrotron X-ray diffraction, the difference in structure relaxation between ordinary and ultrastable amorphous Sb2Se3 was manifested by local structure evolution. Ultrastable amorphous Sb2Se3 showed the smallest surface roughness and highest refractive index, the mechanism behind was further discussed in terms of fast molecular mobility and molecular orientation during vapor deposition. Formation of ultrastable amorphous Sb2Se3 demonstrated a promising avenue to obtain novel functional amorphous semiconductor with modulated structure and property.

  19. Imprinting bulk amorphous alloy at room temperature

    SciTech Connect

    Kim, Song-Yi; Park, Eun-Soo; Ott, Ryan T.; Lograsso, Thomas A.; Huh, Moo-Young; Kim, Do-Hyang; Eckert, Jürgen; Lee, Min-Ha

    2015-11-13

    We present investigations on the plastic deformation behavior of a brittle bulk amorphous alloy by simple uniaxial compressive loading at room temperature. A patterning is possible by cold-plastic forming of the typically brittle Hf-based bulk amorphous alloy through controlling homogenous flow without the need for thermal energy or shaping at elevated temperatures. The experimental evidence suggests that there is an inconsistency between macroscopic plasticity and deformability of an amorphous alloy. Moreover, imprinting of specific geometrical features on Cu foil and Zr-based metallic glass is represented by using the patterned bulk amorphous alloy as a die. These results demonstrate the ability of amorphous alloys or metallic glasses to precisely replicate patterning features onto both conventional metals and the other amorphous alloys. In conclusion, our work presents an avenue for avoiding the embrittlement of amorphous alloys associated with thermoplastic forming and yields new insight the forming application of bulk amorphous alloys at room temperature without using heat treatment.

  20. Imprinting bulk amorphous alloy at room temperature

    PubMed Central

    Kim, Song-Yi; Park, Eun-Soo; Ott, Ryan T.; Lograsso, Thomas A.; Huh, Moo-Young; Kim, Do-Hyang; Eckert, Jürgen; Lee, Min-Ha

    2015-01-01

    We present investigations on the plastic deformation behavior of a brittle bulk amorphous alloy by simple uniaxial compressive loading at room temperature. A patterning is possible by cold-plastic forming of the typically brittle Hf-based bulk amorphous alloy through controlling homogenous flow without the need for thermal energy or shaping at elevated temperatures. The experimental evidence suggests that there is an inconsistency between macroscopic plasticity and deformability of an amorphous alloy. Moreover, imprinting of specific geometrical features on Cu foil and Zr-based metallic glass is represented by using the patterned bulk amorphous alloy as a die. These results demonstrate the ability of amorphous alloys or metallic glasses to precisely replicate patterning features onto both conventional metals and the other amorphous alloys. Our work presents an avenue for avoiding the embrittlement of amorphous alloys associated with thermoplastic forming and yields new insight the forming application of bulk amorphous alloys at room temperature without using heat treatment. PMID:26563908

  1. Amorphous rare earth magnet powders

    SciTech Connect

    Sellers, C.H.; Branagan, D.J.; Hyde, T.A.; Lewis, L.H.; Panchanathan, V.

    1996-08-01

    Gas atomization (GA) processing does not generally have a high enough cooling rate to produce the initial amorphous microstructure needed to obtain optimal magnetic properties in RE{sub 2}Fe{sub 14}B alloys. Phase separation and an underquenched microstructure result from detrimental {alpha}-Fe precipitation, and the resulting magnetic domain structure is very coarse. Additionally, there is a dramatic dependence of the magnetic properties on the cooling rate (and therefore the particle size) and the powders can be sensitive to environmental degradation. Alloy compositions designed just for GA (as opposed to melt spinning) are necessary to produce an amorphous structure that can be crystallized to result in a fine structure with magnetic properties which are independent of particle size. The addition of titanium and carbon to the melt has been found to change the solidification process sufficiently to result in an ``overquenched`` state in which most of the powder size fractions have an amorphous component. Crystallization with a brief heat treatment produces a structure which has improved magnetic properties, in part due to the ability to use compositions with higher Fe contents without {alpha}-Fe precipitation. Results from magnetometry, magnetic force microscopy, and x-ray analyses will be used to contrast the microstructure, domain structure, and magnetic properties of this new generation of amorphous powders with their multiphase predecessors.

  2. Amorphous titanium-oxide supercapacitors

    NASA Astrophysics Data System (ADS)

    Fukuhara, Mikio; Kuroda, Tomoyuki; Hasegawa, Fumihiko

    2016-10-01

    The electric capacitance of an amorphous TiO2-x surface increases proportionally to the negative sixth power of the convex diameter d. This occurs because of the van der Waals attraction on the amorphous surface of up to 7 mF/cm2, accompanied by extreme enhanced electron trapping resulting from both the quantum-size effect and an offset effect from positive charges at oxygen-vacancy sites. Here we show that a supercapacitor, constructed with a distributed constant-equipment circuit of large resistance and small capacitance on the amorphous TiO2-x surface, illuminated a red LED for 37 ms after it was charged with 1 mA at 10 V. The fabricated device showed no dielectric breakdown up to 1,100 V. Based on this approach, further advances in the development of amorphous titanium-dioxide supercapacitors might be attained by integrating oxide ribbons with a micro-electro mechanical system.

  3. Model for amorphous aggregation processes

    NASA Astrophysics Data System (ADS)

    Stranks, Samuel D.; Ecroyd, Heath; van Sluyter, Steven; Waters, Elizabeth J.; Carver, John A.; von Smekal, Lorenz

    2009-11-01

    The amorphous aggregation of proteins is associated with many phenomena, ranging from the formation of protein wine haze to the development of cataract in the eye lens and the precipitation of recombinant proteins during their expression and purification. While much literature exists describing models for linear protein aggregation, such as amyloid fibril formation, there are few reports of models which address amorphous aggregation. Here, we propose a model to describe the amorphous aggregation of proteins which is also more widely applicable to other situations where a similar process occurs, such as in the formation of colloids and nanoclusters. As first applications of the model, we have tested it against experimental turbidimetry data of three proteins relevant to the wine industry and biochemistry, namely, thaumatin, a thaumatinlike protein, and α -lactalbumin. The model is very robust and describes amorphous experimental data to a high degree of accuracy. Details about the aggregation process, such as shape parameters of the aggregates and rate constants, can also be extracted.

  4. Optical absorption in amorphous silicon

    SciTech Connect

    O`Leary, S.K.; Zukotynski, S.; Perz, J.M.; Sidhu, L.S.

    1996-12-31

    The role that disorder plays in shaping the form of the optical absorption spectrum of hydrogenated amorphous silicon is investigated. Disorder leads to a redistribution of states, which both reduces the Tauc gap and broadens the absorption tail. The observed relationship between the Tauc gap and the breadth of the absorption tail is thus explained.

  5. Amorphous titanium-oxide supercapacitors

    PubMed Central

    Fukuhara, Mikio; Kuroda, Tomoyuki; Hasegawa, Fumihiko

    2016-01-01

    The electric capacitance of an amorphous TiO2-x surface increases proportionally to the negative sixth power of the convex diameter d. This occurs because of the van der Waals attraction on the amorphous surface of up to 7 mF/cm2, accompanied by extreme enhanced electron trapping resulting from both the quantum-size effect and an offset effect from positive charges at oxygen-vacancy sites. Here we show that a supercapacitor, constructed with a distributed constant-equipment circuit of large resistance and small capacitance on the amorphous TiO2-x surface, illuminated a red LED for 37 ms after it was charged with 1 mA at 10 V. The fabricated device showed no dielectric breakdown up to 1,100 V. Based on this approach, further advances in the development of amorphous titanium-dioxide supercapacitors might be attained by integrating oxide ribbons with a micro-electro mechanical system. PMID:27767103

  6. Nd:YAG breech mounted laser igniter

    NASA Astrophysics Data System (ADS)

    Hardy, Christopher R.; Myers, Michael J.; Myers, John D.; Gadson, Robert L.; Leone, Joseph; Fay, Josiah W.; Boyd, Kevin

    2005-09-01

    Nd:YAG lasers have been successfully used to demonstrate laser ignition of howitzer propellant charges including bag, stick, and the Modular Artillery Charge System (MACS). Breech Mount Laser Ignition Systems (BMLIS) have been designed, installed and tested on many artillery systems, including the US Army's M109A6 Paladin, M198, M777 Light Weight, Crusader, and Non-Line-of-Sight Cannon (NLOS-C). The NLOS-C incorporates advanced weapon technologies, to include a BMLIS. United Defense's Armament Systems Division has recently designed and built a NLOS-C System Demonstrator that uses a BMLIS that incorporates Kigre's patented square pulse technology. NLOS-C is one of the weapon systems being developed for use with the US Army's "systems of systems" Future Combat System (FCS), Manned Ground Vehicles (MGV) program, and is currently undergoing development testing at Yuma Proving Grounds. In this paper we discuss many technical aspects of an artillery laser ignition system and present BMLIS test data obtained from actual gun firings conducted with a number of different US Army howitzer platforms.

  7. Sulcular debridement with pulsed Nd:YAG

    NASA Astrophysics Data System (ADS)

    Harris, David M.; Gregg, Robert H., II; McCarthy, Delwin K.; Colby, Leigh E.; Tilt, Lloyd V.

    2002-06-01

    We present data supporting the efficacy of the procedure, laser sulcular debridement (laser curettage), as an important component in the treatment of inflammatory periodontal disease. Laser Assisted New Attachment Procedure (LANAP) is a detailed protocol for the private practice treatment of gum disease that incorporates use of the PerioLase pulsed Nd:YAG Dental Laser for laser curettage. Laser curettage is the removal of diseased or inflamed soft tissue from the periodontal pocket with a surgical dental laser. The clinical trial conducted at The University of Texas HSC at San Antonio, Texas, evaluated laser curettage as an adjunct to scaling and root planing. They measured traditional periodontal clinical indices and used a questionnaire to evaluate patient comfort and acceptance. The Texas data (N=10 patients) are compared with pocket depth changes following LANAP. LANAP data were obtained from a retrospective review of patient records at three private practices (N=65). No significant differences in post treatment probe depth changes were found among the four centers indicating that the procedure produced consistent, favorable outcomes, and that results from controlled scientific clinical trials can be replicated in private practices. Reduction in pocket depths following laser treatment compare well with results obtained with scalpel surgery. The use of the laser offers additional benefits. We also present quantitative evidence from digitized radiographs of increased bone density in affected areas following LANAP.

  8. Nd:YAG laser welding experiments

    SciTech Connect

    Akau, R.L.; Keicher, D.M.; Fuerschbach, P.W.; Lienert, T.J.

    1985-10-01

    Laser-beam/plume interaction experiments were conducted with a pulsed Nd:YAG laser. A high speed camera was used to study plume growth phenomena and to determine maximum plume velocities. Tests were done on four different metals: Aluminum 1100, Molybdenum, Nickel 200, and Stainless Steel 304. Previous laser welding experiments have indicated that the vapor plume ejected from the irradiated base material significantly attenuates the laser beam energy for Nickel 200 and Stainless Steel 304. To substantiate this observation, the plume was subjected to a cross flow of argon gas. Metallurgical studies showed a significant increase in weld penetration for all materials except for Aluminum. These experiments also indicated that the plume ejects normal to the base material. Thus, the specimen was tilted at different angles in an attempt to reduce laser beam attenuation. Results showed no significant increase in weld depth when the tilt angle was increased. Mass loss measurements were also performed and the experimental data were an order-of-magnitude less than those predicted by a numerical laser welding code.

  9. CMO YAG laser damage test facility

    SciTech Connect

    Hue, J.; Dijon, J.; Lyan, P.

    1996-12-31

    The CMO YAG laser damage test facility, which is equipped with a 30Hz laser, is presented in this paper. The main points are described below: (1) The characteristics of the laser beam and the in situ damage detection technique (a scattered light measurement system) are perfectly suited to work up to the frequency of the laser. They are monitored in real time, and work at three wavelengths: 1064 nm, 532 nm, 355 nm. (2) With this same shutter, it is possible to automatically stop the laser on the pulse which induces the first damages. These automatic capabilities enable the samples to be tested quickly. (3) A Nomarski microscope supplied with a 16-bit CCD camera enables the test sites to be photographed before and after the laser interaction. Image processing enables the authors to extract the first damages. before and after the laser interaction. Image processing enables them to extract the first damages. (4) Six pulse widths are available (between 3ns and 13ns). Therefore, with all these characterization tools, many kinds of laser tests may be considered. These different features are illustrated by experimental results (1-on-1 test or R-on-1 test).

  10. Lamp pumped Nd:YAG laser. Space-qualifiable Nd:YAG laser for optical communications

    NASA Technical Reports Server (NTRS)

    Ward, K. B.

    1973-01-01

    Results are given of a program concerned with the design, fabrication, and evaluation of alkali pump lamps for eventual use in a space qualified Nd:YAG laser system. The study included evaluation of 2mm through 6mm bore devices. Primary emphasis was placed upon the optimization of the 4mm bore lamp and later on the 6mm bore lamp. As part of this effort, reference was made to the Sylvania work concerned with the theoretical modeling of the Nd:YAG laser. With the knowledge gained, a projection of laser performance was made based upon realistic lamp parameters which should easily be achieved during following developmental efforts. Measurements were made on the lamp performance both in and out of the cavity configuration. One significant observation was that for a constant vapor pressure device, the spectral and fluorescent output did not vary for vacuum or argon environment. Therefore, the laser can be operated in an inert environment (eg. argon) with no degradation in output. Laser output of 3.26 watts at 430 watts input was obtained for an optimized 4mm bore lamp.

  11. Efficient corner-pumped Nd:YAG/YAG composite slab 1.1 µm laser.

    PubMed

    Liu, Huan; Liu, Qiang; Gong, Mali

    2010-09-13

    Corner pumping is a new pumping scheme for diode-pumped solid-state lasers, which has the advantages of high pump efficiency and favorable pump uniformity. A continuous-wave corner-pumped Nd:YAG/ YAG composite slab multi-wavelength laser at around 1.1 µm is demonstrated. The maximal output power is up to 12.06 W with an optical-to-optical conversion efficiency of 24%. At an output power of 10.3 W, the M(2) factors of beam quality at width and thickness directions are 7.71 and 2.44, respectively. With a LBO crystal inserted in the cavity, continuous-wave yellow-green laser with an output power of 841 mW is obtained. The experimental results show that a corner-pumping is a feasible scheme in the design of diode-pumped solid-state 1.1 µm lasers and their frequency-doubling to the yellow-green with low or medium output powers.

  12. Flexible amorphous metal films with high stability

    NASA Astrophysics Data System (ADS)

    Liu, M.; Cao, C. R.; Lu, Y. M.; Wang, W. H.; Bai, H. Y.

    2017-01-01

    We report the formation of amorphous Cu50Zr50 films with a large-area of more than 100 cm2. The films were fabricated by ion beam assisted deposition with a slow deposition rate at moderate temperature. The amorphous films have markedly enhanced thermal stability, excellent flexibility, and high reflectivity with atomic level smoothness. The multifunctional properties of the amorphous films are favorites in the promising applications of smart skin or wearable devices. The method of preparing highly stable amorphous metal films by tuning the deposition rate instead of deposition temperature could pave a way for exploring amorphous metal films with unique properties.

  13. Er:YAG laser debonding of porcelain veneers

    NASA Astrophysics Data System (ADS)

    Buu, Natalie; Morford, Cynthia; Finzen, Frederick; Sharma, Arun; Rechmann, Peter

    2010-02-01

    The removal of porcelain veneers using Er:YAG lasers has not been previously described in the scientific literature. This study was designed to systematically investigate the efficacy of an Er:YAG laser on veneer debonding without damaging the underlying tooth structure, as well as preserving a new or misplaced veneer. Initially, Fourier Transform Infrared Spectroscopy (FTIR) was used on flat porcelain veneer samples (IPS Empress Esthetic; Ivoclar Vivadent, Amherst, NY) to assess which infrared laser wavelengths are transmitted through the veneer. Additionally, FTIR spectra from a veneer bonding cement (RelyX Veneer Cement A1; 3M ESPE, St. Paul, MN) were obtained. While the veneer material showed no characteristic water absorption bands in the FTIR, the bonding cement has a broad H2O/OH absorption band coinciding with the ER:YAG laser emission wavelength. Consequently Er:YAG laser energy transmission through different veneer thicknesses was measured. The porcelain veneers transmitted 11 - 18 % of the incident Er:YAG laser energy depending on their thicknesses (Er:YAG laser: LiteTouch by Syneron; wavelength 2,940 nm, 10 Hz repetition rate, pulse duration 100 μs at 133 mJ/pulse; straight sapphire tip 1,100 μm diameter; Syneron, Yokneam, Israel). Initial signs of cement ablation occurred at approximately 1.8 - 4.0 J/cm2. This can be achieved by irradiating through the veneer with the fiber tip positioned at a distance of 3-6 mm from the veneer surface, and operating the Er:YAG laser with 133 mJ output energy. All eleven veneers bonded on extracted anterior incisor teeth were easily removed using the Er:YAG laser. The removal occurred without damaging underlying tooth structure as verified by light microscopic investigation (Incident Light Microscope Olympus B 50, Micropublisher RTV 3.3 MP, Image Pro software, Olympus). The debonding mainly occurred at the cement/veneer interface. When the samples were stored in saline solution for 5 days and/or an air-waterspray was

  14. Highly efficient solar-pumped Nd:YAG laser.

    PubMed

    Liang, Dawei; Almeida, Joana

    2011-12-19

    The recent progress in solar-pumped laser with Fresnel lens and Cr:Nd:YAG ceramic medium has revitalized solar laser researches, revealing a promising future for renewable reduction of magnesium from magnesium oxide. Here we show a big advance in solar laser collection efficiency by utilizing an economical Fresnel lens and a most widely used Nd:YAG single-crystal rod. The incoming solar radiation from the sun is focused by a 0.9 m diameter Fresnel lens. A dielectric totally internally reflecting secondary concentrator is employed to couple the concentrated solar radiation from the focal zone to a 4 mm diameter Nd:YAG rod within a conical pumping cavity. 12.3 W cw laser power is produced, corresponding to 19.3 W/m(2) collection efficiency, which is 2.9 times larger than the previous results with Nd:YAG single-crystal medium. Record-high slope efficiency of 3.9% is also registered. Laser beam quality is considerably improved by pumping a 3 mm diameter Nd:YAG rod.

  15. Clinical application of erbium:YAG laser in periodontology.

    PubMed

    Ishikawa, Isao; Aoki, Akira; Takasaki, Aristeo Atsushi

    2008-01-01

    Various lasers have been introduced for the treatment of oral diseases and their applications in dental clinics have become a topic of much interest among practitioners. Technological advances and improvements have increased the choices of the available laser systems for oral use. Among them, a recently developed erbium-doped:yttrium aluminum garnet (Er:YAG) laser system possesses suitable characteristics for oral soft and hard tissue ablation. Due to its high absorption in water, an effective ablation with a very thin surface interaction occurs on the irradiated tissues without any major thermal damage to the irradiated and surrounding tissues. In the field of periodontics, the application of Er:YAG laser for periodontal hard tissue has begun with studies from Japanese and German researchers. Several in vitro and clinical studies have already demonstrated an effective application of the Er:YAG laser for calculus removal and decontamination of the diseased root surface in periodontal non-surgical and surgical procedures. However, further studies are required to better understand the various effects of Er:YAG laser irradiation on biological tissues for its safe and effective application during periodontal and implant therapy. Randomized controlled clinical trials and more basic studies have to be encouraged and performed to confirm the status of Er:YAG laser treatment as an adjunct or alternative to conventional mechanical periodontal therapy. In this paper, the advantages and current clinical applications of this laser in periodontics and implant dentistry are summarized based on current scientific evidence.

  16. Topological Insulators in Amorphous Systems

    NASA Astrophysics Data System (ADS)

    Agarwala, Adhip; Shenoy, Vijay B.

    2017-06-01

    Much of the current understanding of topological insulators, which informs the experimental search for topological materials and systems, is based on crystalline band theory, where local electronic degrees of freedom at different crystal sites hybridize with each other in ways that produce nontrivial topology. Here we provide a novel theoretical demonstration of realizing topological phases in amorphous systems, as exemplified by a set of sites randomly located in space. We show this by constructing hopping models on such random lattices whose gapped ground states are shown to possess nontrivial topological nature (characterized by Bott indices) that manifests as quantized conductances in systems with a boundary. Our study adds a new dimension, beyond crystalline solids, to the search for topological systems by pointing to the promising possibilities in amorphous solids and other engineered random systems.

  17. Topological Insulators in Amorphous Systems.

    PubMed

    Agarwala, Adhip; Shenoy, Vijay B

    2017-06-09

    Much of the current understanding of topological insulators, which informs the experimental search for topological materials and systems, is based on crystalline band theory, where local electronic degrees of freedom at different crystal sites hybridize with each other in ways that produce nontrivial topology. Here we provide a novel theoretical demonstration of realizing topological phases in amorphous systems, as exemplified by a set of sites randomly located in space. We show this by constructing hopping models on such random lattices whose gapped ground states are shown to possess nontrivial topological nature (characterized by Bott indices) that manifests as quantized conductances in systems with a boundary. Our study adds a new dimension, beyond crystalline solids, to the search for topological systems by pointing to the promising possibilities in amorphous solids and other engineered random systems.

  18. Pump beam waist-dependent pulse energy generation in Nd:YAG/Cr4+:YAG passively Q-switched microchip laser

    NASA Astrophysics Data System (ADS)

    Li, Chao-yu; Dong, Jun

    2016-08-01

    The incident pump beam waist-dependent pulse energy generation in Nd:YAG/Cr4+:YAG composite crystal passively Q-switched microchip laser has been investigated experimentally and theoretically by moving the Nd:YAG/Cr4+:YAG composite crystal along the pump beam direction. Highest pulse energy of 0.4 mJ has been generated when the Nd:YAG/Cr4+:YAG composite crystal is moved about 6 mm away from the focused pump beam waist. Laser pulses with pulse width of 1.7 ns and peak power of over 235 kW have been achieved. The theoretically calculated effective laser beam area at different positions of Nd:YAG/Cr4+:YAG composite crystal along the pump beam direction is in good agreement with the experimental results. The highest peak power can be generated by adjusting the pump beam waist incident on the Nd:YAG/Cr4+:YAG composite crystal to optimize the effective laser beam area in passively Q-switched microchip laser.

  19. Can YAG screen accept LEReC bunch train?

    SciTech Connect

    Seletskiy, S.; Thieberger, P.; Miller, T.

    2016-05-18

    LEReC RF diagnostic beamline is supposed to accept 250 us long pulse trains of 1.6 MeV – 2.6 MeV (kinetic energy) electrons. This beamline is equipped with YAG profile monitor. Since we are interested in observing only the last macro bunch in the train, one of the possibilities is to install a fast kicker and a dedicated dump upstream of the YAG screen (and related diagnostics equipment). This approach is expensive and challenging from engineering point of view. Another possibility is to send the whole pulse train to the YAG screen and to use a fast gated camera (such as Imperex B0610 with trigger jitter under 60ns) to observe the image from the last pulse only. In this paper we study the feasibility of the last approach.

  20. Yb:YAG Lasers for Space Based Remote Sensing

    NASA Technical Reports Server (NTRS)

    Ewing, J.J.; Fan, T. Y.

    1998-01-01

    Diode pumped solid state lasers will play a prominent role in future remote sensing missions because of their intrinsic high efficiency and low mass. Applications including altimetry, cloud and aerosol measurement, wind velocity measurement by both coherent and incoherent methods, and species measurements, with appropriate frequency converters, all will benefit from a diode pumped primary laser. To date the "gold standard" diode pumped Nd laser has been the laser of choice for most of these concepts. This paper discusses an alternate 1 micron laser, the YB:YAG laser, and its potential relevance for lidar applications. Conceptual design analysis and, to the extent possible at the time of the conference, preliminary experimental data on the performance of a bread board YB:YAG oscillator will be presented. The paper centers on application of YB:YAG for altimetry, but extension to other applications will be discussed.

  1. Er:YAG laser metal and ceramic bracket debonding

    NASA Astrophysics Data System (ADS)

    Dostálová, Tat'jana; Remeš, Marek; Jelínková, Helena; Å ulc, Jan; Němec, Michal; Vyhlídal, David

    2016-02-01

    The goal of the study was investigation of Er:YAG radiation (wavelength 2.94 μm) interaction with various metal and ceramic brackets and adhesive materials. The source of radiation was a free-running Er: YAG laser generating pulses with energy 280 mJ, 250 μs long and repetition rate 6 Hz (mean power 1.7 W). During the treatment lasting 140 s, water cooling was implemented and only the brackets were irradiated. It has been observed that the brackets were removed easily after the Er:YAG laser irradiation, and temperature rise was limited also for metal brackets. SEM investigation has confirmed less damage of enamel in comparison with non-irradiated samples.

  2. Erbium:YAG laser resurfacing using a novel portable device.

    PubMed

    Gordon, James; Khan, Misbah H; Khatri, Khalil A

    2007-05-01

    Laser resurfacing of facial rhytids has become a popular treatment for many patients who have wrinkles, photodamage, and acne scarring. Erbium:YAG laser resurfacing has emerged as one of the safer, more effective methods of facial rejuvenation and its increasing popularity has led to its widespread use for resurfacing. However, size and high initial and maintenance cost are among the problems with currently available laser devices. The LightPod portable Erbium:YAG laser from Aerolase offers a new paradigm for more cost effective means of performing ablative resurfacing with reduced initial and maintenance cost and the ease of portability with significantly reduced size and weight. The objective of this pilot study was to analyze the efficacy of The LightPod Erbium:YAG laser in different skin types for various indications.

  3. Efficient Q-switched Tm:YAG ceramic slab laser.

    PubMed

    Zhang, Shuaiyi; Wang, Mingjian; Xu, Lin; Wang, Yan; Tang, Yulong; Cheng, Xiaojin; Chen, Weibiao; Xu, Jianqiu; Jiang, Benxue; Pan, Yubai

    2011-01-17

    Characteristics of Tm:YAG ceramic for high efficient 2-μm lasers are analyzed. Efficient diode end-pumped continuous-wave and Q-switched Tm:YAG ceramic lasers are demonstrated. At the absorbed pump power of 53.2W, the maximum continuous wave (cw) output power of 17.2 W around 2016 nm was obtained with the output transmission of 5%. The optical conversion efficiency is 32.3%, corresponding to a slope efficiency of 36.5%. For Q-switched operation, the shortest width of 69 ns was achieved with the pulse repetition frequency of 500 Hz and single pulse energy of 20.4 mJ, which indicates excellent energy storage capability of the Tm:YAG ceramic.

  4. Prominent 946 lines induced from flashlamp pumped Nd: YAG rod

    NASA Astrophysics Data System (ADS)

    Bidin, Noriah; Zainal, Roslinda; Daud, Yaacob Mat; Pourmand, Seyed Ebrahim; Bakhtiar, Hazri

    2012-06-01

    Spectroscopic properties of Nd:YAG laser rod pumped by a new developed flashlamp is investigated. A new power supply is constructed to power xenon flashlamp. A 1 at.% Nd:YAG laser rod is transversely pumped by the flashlamp and stabilized by a water cooling system operated at ambient temperature of 20°C. The absorption and emission spectrum of the flashlamp pumped Nd:YAG rod is analyzed via spectroscopy technique. The peak absorption line is identified to be at 882 nm. The dominant emission line obtained from transition 4F3/2→4I9/2 comprised of quasi three level laser at 938.5 and 946 nm with the corresponding cross section of 2.42×10-19cm2 and 3.04×10-19cm2 respectively. This cross section is found almost ten times greater than the usual one.

  5. Q-Switched Nd: YAG Laser Micro-Machining System

    SciTech Connect

    Messaoud, S.; Allam, A.; Siserir, F.; Bouceta, Y.; Kerdja, T.; Ouadjaout, D.

    2008-09-23

    In this paper, we present the design of a low cost Q-switched Nd: YAG laser micro-machining system for photo masks fabrication. It consists of: Nd:YAG laser source, beam delivery system, X-Y table, PC, The CCD camera and TV monitor. The synchronization between the laser source and the X-Y table is realised by NI PCI-7342, the two axis MID-7602 and LabVIEW based program. The first step of this work consists of engraving continuous and discontinuous lines on a thin film metal with a 100 {mu}m resolution by using the YG 980 Quantel Q-switched Nd:YAG laser.

  6. X-ray and thermally stimulated luminescence in YAG

    SciTech Connect

    Smol'skaya, L.P.; Martynovich, E.F.; Davydchenko, A.G.; Smirnova, S.A.

    1987-07-01

    Yttrium aluminum garnet Y/sub 3/Al/sub 5/O/sub 12/ (YAG) crystals with rare earth ion (REI) impurities are widely used in laser technology and also in the capacity of cathode luminophors. Recently they have attracted the attention of researchers for their possible use as x-ray luminophors, scintillators, and thermoluminescent detectors. However, research in these areas is not very comprehensive. This work compares the intensity of x-ray luminescence (XRL) and the inertial characteristics of YAG monocrystals that are activated by REI (Ce/sup 3 +/, Sm/sup 3 +/, Dy/sup 3 +/, Tm/sup 3 +/, and Er/sup 3 +/), with the x-ray luminophore CsI-Tl. Since the existence of deep capture levels exerts a significant influence on the useful properties of x-ray luminophores, YAG thermoluminescence was also studied.

  7. Electrically Tunable Nd:YAG waveguide laser based on Graphene

    PubMed Central

    Ma, Linan; Tan, Yang; Akhmadaliev, Shavkat; Zhou, Shengqiang; Chen, Feng

    2016-01-01

    We demonstrate a tunable hybrid Graphene-Nd:YAG cladding waveguide laser exploiting the electro-optic and the Joule heating effects of Graphene. A cladding Nd:YAG waveguide was fabricated by the ion irradiation. The multi-layer graphene were transferred onto the waveguide surface as the saturable absorber to get the Q-switched pulsed laser oscillation in the waveguide. Composing with appropriate electrodes, graphene based capacitance and heater were formed on the surface of the Nd:YAG waveguide. Through electrical control of graphene, the state of the hybrid waveguide laser was turned on or off. And the laser operation of the hybrid waveguide was electrically tuned between the continuous wave laser and the nanosecond pulsed laser. PMID:27833114

  8. Electrically Tunable Nd:YAG waveguide laser based on Graphene

    NASA Astrophysics Data System (ADS)

    Ma, Linan; Tan, Yang; Akhmadaliev, Shavkat; Zhou, Shengqiang; Chen, Feng

    2016-11-01

    We demonstrate a tunable hybrid Graphene-Nd:YAG cladding waveguide laser exploiting the electro-optic and the Joule heating effects of Graphene. A cladding Nd:YAG waveguide was fabricated by the ion irradiation. The multi-layer graphene were transferred onto the waveguide surface as the saturable absorber to get the Q-switched pulsed laser oscillation in the waveguide. Composing with appropriate electrodes, graphene based capacitance and heater were formed on the surface of the Nd:YAG waveguide. Through electrical control of graphene, the state of the hybrid waveguide laser was turned on or off. And the laser operation of the hybrid waveguide was electrically tuned between the continuous wave laser and the nanosecond pulsed laser.

  9. Yb:YAG Lasers for Space Based Remote Sensing

    NASA Technical Reports Server (NTRS)

    Ewing, J.J.; Fan, T. Y.

    1998-01-01

    Diode pumped solid state lasers will play a prominent role in future remote sensing missions because of their intrinsic high efficiency and low mass. Applications including altimetry, cloud and aerosol measurement, wind velocity measurement by both coherent and incoherent methods, and species measurements, with appropriate frequency converters, all will benefit from a diode pumped primary laser. To date the "gold standard" diode pumped Nd laser has been the laser of choice for most of these concepts. This paper discusses an alternate 1 micron laser, the YB:YAG laser, and its potential relevance for lidar applications. Conceptual design analysis and, to the extent possible at the time of the conference, preliminary experimental data on the performance of a bread board YB:YAG oscillator will be presented. The paper centers on application of YB:YAG for altimetry, but extension to other applications will be discussed.

  10. Growth of single-crystal YAG fiber optics.

    PubMed

    Nie, Craig D; Bera, Subhabrata; Harrington, James A

    2016-07-11

    Single-crystal YAG (Y3Al5O12) fibers have been grown by the laser heated pedestal growth technique with losses as low as 0.3 dB/m at 1.06 μm. These YAG fibers are as long as about 60 cm with diameters around 330 μm. The early fibers were grown from unoriented YAG seed fibers and these fibers exhibited facet steps or ridges on the surface of the fiber. However, recently we have grown fibers using an oriented seed to grow step-free fibers. Scattering losses made on the fibers indicate that the scattering losses are equal to about 30% of the total loss.

  11. Use of the holmium:YAG laser in urology

    NASA Astrophysics Data System (ADS)

    Johnson, Douglas E.; Cromeens, Douglas M.; Price, Roger E.

    1992-06-01

    The Holmium:YAG (Ho:YAG) laser operating at a wavelength of 2.1 micrometers with a maximum power of 15 watts (W) and 10 different pulse-energy settings was systematically evaluated on kidney, bladder, prostate, ureteral, and vasal tissue, and was used to perform various urologic surgical procedures (partial nephrectomy, transurethral laser incision of the prostate, and laser-assisted vasovasostomy) in the dog. By using the SurgiTomeTM 3- inch straight delivery system with an energy-pulse setting of 0.5 joules (J) at 20 Hz (10 W), partial nephrectomies required slightly longer operating times (15 minutes) than when similar procedures were performed using the Neodymium:YAG (Nd:YAG) laser and a free GI fiber at 59 to 83 W (4 - 7 minutes); however, the total energy required was considerably less. Hemostasis was excellent and no sutures were required to control bleeding. Transurethral incisions of the prostate using TV monitoring were made at the 4 and 8 o'clock positions extending from the colliculus seminalis through the vesical neck with an energy/pulse setting of 1.0 J at 15 Hz (15 W). Attempts at laser-assisted vasovasostomies were unsuccessful due to excessive thermal affect. The LaparoTomeTM Delivery System proved helpful in performing laparoscopic pelvic lymphadenectomy in the pig. Our investigations showed that the Ho:YAG laser possesses both excellent cutting and adequate hemostatic abilities even in a fluid medium. Although these results are preliminary, we believe that the Ho:YAG laser is well suited for urologic surgery and may well become the 'urologist's laser of the future.'

  12. Neodymium-YAG transscleral cyclophotocoagulation. The role of pigmentation

    SciTech Connect

    Cantor, L.B.; Nichols, D.A.; Katz, L.J.; Moster, M.R.; Poryzees, E.; Shields, J.A.; Spaeth, G.L. )

    1989-08-01

    Using a rabbit model we investigated the role of pigmentation of the ciliary body in obtaining ciliodestruction by neodymium-YAG transscleral cyclophotocoagulation. There was marked destruction of the ciliary body in pigmented rabbit eyes, but no histologic effect was observed in albino rabbit eyes. These findings suggest that pigmentation of the ciliary body is important for obtaining the desired response from neodymium-YAG transscleral cyclophotocoagulation in rabbit eyes by our technique. Further study is necessary to define the role of pigmentation in human eyes in this treatment modality.

  13. Perendoscopic Nd:YAG laser therapy of colorectal neoplasms

    NASA Astrophysics Data System (ADS)

    Norberto, Lorenzo; Ranzato, Riccardo; Marino, Saverio; Erroi, F.; Angriman, Imerio; Donadi, Michele; Paratore, S.; Scuderi, G.; D'Amico, D. F.

    1996-01-01

    The range of application of Nd:YAG laser is now wide and of particular interest in the treatment of neoplastic lesions of the large bowel, both benign and malignant, which, besides the debilitating of vegetative lesions, may also provide a good hemostasis of the bleeding ones. Yag laser treatment of malignancies is indicated in patients not suitable for surgery due to the extent of the disease or to the high anesthesiologic/surgical risk. The treatment of choice for benign neoplasms is represented by endoscopic polypectomy, being Yag laser therapy reserved to patients with very large polyps and with a high anesthesiologic risk. Yag laser therapy is also recommended in teleangiectasies with active or previous bleeding, since it allows the complete ablation of such lesions with subsequent outstanding hemostasis. Furthermore this treatment may be advantageously associated to other operative endoscopic procedures, such as diatermotherapy, dilatation and injection therapy. It is also to be outlined that Yag laser therapy is currently used to cure benign diseases and for the palliation of advanced cancer in inoperable patients. Our laser instrument is an Nd:Yag laser MBB Medilas 2 with maximum power of 100 watts at the tip, with 'non-contact' laser fibers. We use flexible optic fiberendoscopes of several sizes, according to the type of lesion to be treated. Moreover we have employed both Savary dilators of progressive caliber from 5 to 15 mm and Rigiflex pneumatic balloons. Adequate bowel preparation by means of isosmotic solution was achieved in patients with non stenotic neoplasm, or evacuative enemas and fluid diet in patients with bowel neoplastic stenoses. The patients were premedicated with benzodiazepines. Stenotic malignant lesions have been treated with endoscopic dilatation before laser treatment. At each session 4,000 - 8,000 joules of energy were administered; all patients received an average of 5 - 6 laser sessions. Followup laser sessions have then been

  14. Nd:YAG Capsulotomy Rates With Two Trifocal Intraocular Lenses.

    PubMed

    Bilbao-Calabuig, Rafael; Llovet-Osuna, Fernando; González-López, Felix; Beltrán, Jaime

    2016-11-01

    To compare Nd:YAG capsulotomy rates following implantation of two diffractive trifocal intraocular lenses (IOLs). This multi-center retrospective analysis included patients who underwent uncomplicated lens phacoemulsification and were implanted with a diffractive trifocal IOL: FineVision MicroF (PhysIOL, Liège, Belgium) or AT Lisa tri 839MP (Carl Zeiss Meditec, Jena, Germany). All surgeries were performed during the same period. The postoperative follow-up period was at least 1 year. Chi-square and Kaplan-Meier tests analyzed non-parametric estimates for survival/failure functions. The Wilcoxon (Breslow) test compared Nd:YAG capsulotomy rates between the two groups. Of 5,130 eyes included, 3,387 were implanted with the FineVision MicroF IOL and 1,743 with the AT Lisa tri 839MP IOL. There were no statistical differences in age, axial length, or IOL power between groups. Nd:YAG capsulotomies were necessary in 330 eyes (9%) in the FineVision group and 408 eyes (23%) in the AT Lisa tri group (P < .001). The probability of having Nd:YAG capsulotomy up to 9 months postoperatively was equal for both lenses. Beyond 9 months, the Nd:YAG capsulotomy rate increased significantly more in the AT Lisa tri group, reaching a probability of 35% for eyes with a follow-up of 34 to 44 months, whereas in the FineVision group the probability was 14% after a follow-up of 37 to 47 months. The differences in survival (without Nd:YAG capsulotomy)/failure (with Nd:YAG capsulotomy) functions were significant (P < .001). Eyes implanted with the FineVision MicroF IOL required significantly fewer Nd:YAG laser capsulotomies than those with the AT Lisa tri 839MP IOL during the first years after implantation. The design of the IOL platforms could account for these differences. [J Refract Surg. 2016;32(11):748-752.]. Copyright 2016, SLACK Incorporated.

  15. Clinical application of the erbium:YAG laser for apicoectomy.

    PubMed

    Komori, T; Yokoyama, K; Takato, T; Matsumoto, K

    1997-12-01

    Recently, an Er:YAG laser has attracted attention because of the possibility of cutting hard tissues with extremely small thermal effects. In this article, we report 8 cases (13 teeth) of apicoectomy using Er:YAG laser. All procedures were performed without using an air turbine or an electric drill. Although the cutting speed of this laser was slightly slower than ordinary methods, its clinical application for apicoectomy has many advantages including absence of discomfort and vibration, less chance for contamination of the surgical site, and reduced risk of trauma to adjacent tissue.

  16. Holmium:YAG laser coronary angioplasty in acute myocardial infarction

    NASA Astrophysics Data System (ADS)

    Topaz, On; Luxenberg, Michael; Schumacher, Audrey

    1994-07-01

    Patients who sustain complicated acute myocardial infarction in whom thrombolytic agents either fail or are contraindicated often need mechanical revascularization other than PTCA. In 24 patients with acute infarction complicated by continuous chest pain and ischemia who either received lytics or with contraindication to lytics, a holmium:YAG laser (Eclipse Surgical Technologies, Palo Alto, CA) was utilized for thrombolysis and plaque ablation. Clinical success was achieved in 23/24 patients, with 23 patients (94%) surviving the acute infarction. Holmium:YAG laser is very effective and safe in thrombolysis and revascularization in this complicated clinical setting.

  17. Next generation Er:YAG fractional ablative laser

    NASA Astrophysics Data System (ADS)

    Heinrich, A.; Vizhanyo, A.; Krammer, P.; Summer, S.; Gross, S.; Bragagna, T.; Böhler, C.

    2011-03-01

    Pantec Biosolutions AG presents a portable fractional ablative laser system based on a miniaturized diode pumped Er:YAG laser. The system can operate at repetition rates up to 500 Hz and has an incorporated beam deflection unit. It is smaller, lighter and cost efficient compared to systems based on lamp pumped Er:YAG lasers and incorporates a skin layer detection to guarantee precise control of the microporation process. The pulse parameters enable a variety of applications in dermatology and in general medicine, as demonstrated by first results on transdermal drug delivery of FSH (follicle stimulating hormone).

  18. Cryogenic Tm: YAG Laser in the Near Infrared

    DTIC Science & Technology

    2015-05-29

    Applications Group. The focus of his work at Lincoln Laboratory has been solid-state lasers including microchip lasers , external - cavity diode lasers ...in bulk Tm:YAG by quasi-cw pumping with a fiber-coupled diode array at 782 nm. Prior demonstrations of this laser transition have been limited...for Tm:YAG operating on the 3H4 - 3H6 transition in the 0.82 µm wavelength range. It can be pumped with efficient diode lasers in the 0.78 - 0.8 µm

  19. Nd:YAG laser treatment of tumors of the oropharynx

    NASA Astrophysics Data System (ADS)

    Lippert, Burkard M.; Folz, Benedikt J.; Werner, Jochen A.

    1998-01-01

    The laser surgical treatment of carcinomas of the upper aerodigestive tract has become an established treatment modality at many otolaryngology departments throughout the laser years. The oncologic results that can be achieved with this surgical technique are quite as good as the results that can be achieved by conventional surgery, the functional results on the other hand often seem to be superior to conventional surgery. The Nd:YAG laser has so far rarely been used as a cutting device in the head and neck region. The fibertom mode is a new technique, which has been developed to make the employment of the Nd:YAG laser as a laser scalpel feasible. Between December 1995 and May 1997 thirty-five patients with squamous cell carinomas of the oral cavity were treated at the Department of Otolaryngology, Head and Neck Surgery of the University of Kiel with the Nd:YAG laser in fibertom mode (30 - 50 Watt, cw-mode, 600 m bare fiber). The operative approach, intra- and postoperative complications, duration of the operation and of the healing process, as well as functional and oncologic results were documented and compared to the retrospectively raised data of a group of patients (n equals 25), that was treated by CO2 laser surgery. When working with the Nd:YAG laser in fibertom mode fewer hemorrhages during the actual dissection could be observed as opposed to dissection with the CO2 laser. By laser dissection with the Nd:YAG laser in fibertom mode the operation had to be interrupted to a much lesser extent for bipolar cautery, thus resulting in a reduced operation time. Until a complete reepithelialization of the laser wound was achieved an interval of 3 - 4 weeks went by. Following Nd:YAG laser excision the healing process was 7 - 10 days delayed when compared to CO2 laser surgery. The functional and oncologic results were quite satisfactory in both groups and no major difference between the two laser systems could be observed. The fibertom mode renders the use of the Nd:YAG

  20. Results of the treatment of hircus with YAG laser

    NASA Astrophysics Data System (ADS)

    Liu, Jian-xun; Zhang, Xinrong

    1993-03-01

    A new technique of treating hircus with YAG laser is described in this paper. One-hundred-fifty patients have been treated and 100% cure rate has been achieved with few complications. Some related problems are discussed. Hircus as a common disease can be treated by many surgical procedures, but none of them can be considered as a perfect one. Some of them may cause pain during operation and other problems postoperatively. Since 1988, 150 patients with hirci have been treated with YAG laser and satisfactory results have been obtained.

  1. Histological study of frequency-doubled Nd:YAG laser trabeculoplasty on monkey eyes

    NASA Astrophysics Data System (ADS)

    Yu, Zi-kui; Wang, Kang-sun; Shi, Hai-yun

    1998-11-01

    Two eyes of a rhesus monkey subject to frequency-doubled Nd:YAG laser LTP were examined by light and electron microscopy twenty-four hours and four weeks postoperatively. Light microscopy demonstrated trabecular meshwork edema, acute inflammatory changes such as the presence of polymorphonuclears and amorphous eosinphilous substance of the Schlemm's canal in the specimen 24 hours after surgery, otherwise, membrane-like extension over the surface of uveal meshwork was found in the tissue four weeks after surgery. Scanning electron microscopy of the specimens excited at earlier stage after irradiation revealed evidences of disruption, coalescence of the trabecular beams and the exudation of deformed erythrocytes among intertrabecular spaces; the specimens excited at later stage showed partial or total occlusion of intertrabecular spaces at laser burn site by a membrane like layer which probably originate from so called trabecular stem cell near the Schwalbe's line. Transmission electron microscopy of the tissue excited at 24 hours post laser showed necrosis of the trabecular cells, collagen fibrils edema, as well a macrophages and pigment cells among intertrabecular spaces; the tissues excited at 4 weeks post laser showed degenerated collagen fibrils and denuded collagen core without superficial trabecular cells.

  2. Ablation rate, caries removal, and restoration using Nd:YAG and Er:YAG lasers and air abrasion

    NASA Astrophysics Data System (ADS)

    White, Joel M.

    1998-04-01

    This study evaluated the ablation rate in dentin and enamel of the Nd:YAG laser (1 - 2W, 10Hz) and the Er:YAG laser (1 - 2.5W, 10Hz), compared to the high-speed drill, low-speed drill and air abrasion (fine and extra-fine particle size). Subsequently, the effectiveness of caries removal and restoration in enamel of the Nd:YAG laser at the same powers and pulse repetition rate was compared to the high-speed drill, low-speed drill, and air abrasion. Enamel and dentin of 1mm thick mid-coronal sections from extracted third molars were ablated by Er:YAG laser ((lambda) equals 2.94 micrometer), Nd:YAG laser ((lambda) equals 1.06 micrometer) both with air/water spray, high-speed drill with 300 carbide bur, and low-speed drill with $1/4 round bur and air abrasions at 160 psi, with fine air abrasion at 50 micrometer and extra fine at 27 micrometer particle size. Removal (ablation) rate defined as dentin or enamel thickness divided by time required for perforation of the samples was determined for lasers, drills and air abrasion. Multifactor randomized ANOVA (p less than 0.05) considered removal rate as a function of treatment conditions. Removal Rate (micrometers per second) Enamel Dentin High-speed drill 273 +/- 47.34 493 +/- 1.73 Low-speed drill 0 42 +/- 14.25 Nd:YAG 2W 0 103 +/- 37 Er:YAG 2W 35 +/- 10 348 +/- 101 Air abrasion/fine 220 +/- 27 433 +/- 99 Air abrasion/extra fine 151 +/- 13 203 +/- 30 Er:YAG laser at 2W 10Hz ablated both enamel and dentin faster than the low-speed drill but slower than the high-speed drill, while the Nd:YAG laser at identical power and pulse rate did not ablate healthy enamel but was capable of removing dentin. To determine caries removal rate in enamel, extracted superficial carious molars (n equals 35) that included minimal explorer penetration and radiographic confirmation of caries extent were selected. Samples were randomly distributed into treatment groups: high-speed drill (HS), low-speed drill (LS), Nd:YAG laser (L), Nd:YAG with air

  3. Comparison of dentin root canal permeability and morphology after irradiation with Nd:YAG, Er:YAG, and diode lasers.

    PubMed

    Esteves-Oliveira, Marcella; de Guglielmi, Camila A B; Ramalho, Karen Müller; Arana-Chavez, Victor E; de Eduardo, Carlos Paula

    2010-09-01

    The aim of this study was to compare the effects of Nd:YAG, Er:YAG, and diode lasers on the morphology and permeability of root canal walls. The three laser wavelengths mentioned interact differently with dentin and therefore it is possible that the permeability changes caused will determine different indications during endodontic treatment. Twenty-eight human single-rooted teeth were instrumented up to ISO 40 and divided into four groups: group C, control (GC), non-laser irradiated; group N (GN), irradiated with Nd:YAG laser; group E (GE), with Er:YAG laser and group D (GD) with diode laser. After that, the roots were filled with a 2% methylene blue dye, divided into two halves and then photographed. The images were analyzed using Image J software and the percentage of dye penetration in the cervical, middle, and apical root thirds were calculated. Additional scanning electron microscopy (SEM) analyses were also performed. The analysis of variance (ANOVA) showed significant permeability differences between all groups in the middle and cervical thirds (p < 0.05). The Tukey test showed that in the cervical third, GN presented means of dye penetration statistically significantly lower than all of the other groups. In the middle third, GE and GD showed statistically higher dye penetration means than GC and GN. SEM analysis showed melted surfaces for GN, clean wall surfaces with open dentinal tubules for GE, and mostly obliterated dentinal tubules for GD. Er:YAG (2,094 nm) laser and diode laser (808 nm) root canal irradiation increase dentinal permeability and Nd:YAG (1,064 nm) laser decreases dentin permeability, within the studied parameters.

  4. On Structure and Properties of Amorphous Materials

    PubMed Central

    Stachurski, Zbigniew H.

    2011-01-01

    Mechanical, optical, magnetic and electronic properties of amorphous materials hold great promise towards current and emergent technologies. We distinguish at least four categories of amorphous (glassy) materials: (i) metallic; (ii) thin films; (iii) organic and inorganic thermoplastics; and (iv) amorphous permanent networks. Some fundamental questions about the atomic arrangements remain unresolved. This paper focuses on the models of atomic arrangements in amorphous materials. The earliest ideas of Bernal on the structure of liquids were followed by experiments and computer models for the packing of spheres. Modern approach is to carry out computer simulations with prediction that can be tested by experiments. A geometrical concept of an ideal amorphous solid is presented as a novel contribution to the understanding of atomic arrangements in amorphous solids. PMID:28824158

  5. Narrow band gap amorphous silicon semiconductors

    DOEpatents

    Madan, A.; Mahan, A.H.

    1985-01-10

    Disclosed is a narrow band gap amorphous silicon semiconductor comprising an alloy of amorphous silicon and a band gap narrowing element selected from the group consisting of Sn, Ge, and Pb, with an electron donor dopant selected from the group consisting of P, As, Sb, Bi and N. The process for producing the narrow band gap amorphous silicon semiconductor comprises the steps of forming an alloy comprising amorphous silicon and at least one of the aforesaid band gap narrowing elements in amount sufficient to narrow the band gap of the silicon semiconductor alloy below that of amorphous silicon, and also utilizing sufficient amounts of the aforesaid electron donor dopant to maintain the amorphous silicon alloy as an n-type semiconductor.

  6. High-beam-quality, efficient operation of passively Q-switched Yb:YAG/Cr:YAG laser pumped by photonic-crystal surface-emitting laser

    NASA Astrophysics Data System (ADS)

    Guo, Xiaoyang; Tokita, Shigeki; Fujioka, Kana; Nishida, Hiro; Hirose, Kazuyoshi; Sugiyama, Takahiro; Watanabe, Akiyoshi; Ishizaki, Kenji; Noda, Susumu; Miyanaga, Noriaki; Kawanaka, Junji

    2017-07-01

    A passively Q-switched Yb:YAG/Cr:YAG laser pumped by a photonic-crystal surface-emitting laser (PCSEL) was developed. Yb:YAG crystal was cryogenically cooled by liquid nitrogen at 77 K. Excellent Gaussian beam profile ( M 2 = 1.02) and high slope efficiency of 58% were demonstrated without using a coupling optics between a laser material and PCSEL.

  7. Amorphous silicon solar cell allowing infrared transmission

    DOEpatents

    Carlson, David E.

    1979-01-01

    An amorphous silicon solar cell with a layer of high index of refraction material or a series of layers having high and low indices of refraction material deposited upon a transparent substrate to reflect light of energies greater than the bandgap energy of the amorphous silicon back into the solar cell and transmit solar radiation having an energy less than the bandgap energy of the amorphous silicon.

  8. Amorphous-Amorphous Phase Separation in API/Polymer Formulations.

    PubMed

    Luebbert, Christian; Huxoll, Fabian; Sadowski, Gabriele

    2017-02-15

    The long-term stability of pharmaceutical formulations of poorly-soluble drugs in polymers determines their bioavailability and therapeutic applicability. However, these formulations do not only often tend to crystallize during storage, but also tend to undergo unwanted amorphous-amorphous phase separations (APS). Whereas the crystallization behavior of APIs in polymers has been measured and modeled during the last years, the APS phenomenon is still poorly understood. In this study, the crystallization behavior, APS, and glass-transition temperatures formulations of ibuprofen and felodipine in polymeric PLGA excipients exhibiting different ratios of lactic acid and glycolic acid monomers in the PLGA chain were investigated by means of hot-stage microscopy and DSC. APS and recrystallization was observed in ibuprofen/PLGA formulations, while only recrystallization occurred in felodipine/PLGA formulations. Based on a successful modeling of the crystallization behavior using the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT), the occurrence of APS was predicted in agreement with experimental findings.

  9. Picosecond and nanosecond laser annealing and simulation of amorphous silicon thin films for solar cell applications

    NASA Astrophysics Data System (ADS)

    Theodorakos, I.; Zergioti, I.; Vamvakas, V.; Tsoukalas, D.; Raptis, Y. S.

    2014-01-01

    In this work, a picosecond diode pumped solid state laser and a nanosecond Nd:YAG laser have been used for the annealing and the partial nano-crystallization of an amorphous silicon layer. These experiments were conducted as an alternative/complementary to plasma-enhanced chemical vapor deposition method for fabrication of micromorph tandem solar cell. The laser experimental work was combined with simulations of the annealing process, in terms of temperature distribution evolution, in order to predetermine the optimum annealing conditions. The annealed material was studied, as a function of several annealing parameters (wavelength, pulse duration, fluence), as far as it concerns its structural properties, by X-ray diffraction, SEM, and micro-Raman techniques.

  10. The physics and applications of amorphous semiconductors

    SciTech Connect

    Madan, A.; Shaw, M.P.

    1988-01-01

    This is a treatise on the physics and applications of the new emerging technology of amorphous semiconductors. The authors focus upon research problems such as the optimization of device performance while also presenting the general physics of amorphous semiconductors. The first part of the book covers hydrogenated amorphous silicon type alloys, whose applications include inexpensive solar cells, thin film transistors, image scanners, electrophotography, optical recording, and gas sensors. The second part of the book discusses amorphous chalcogenides, whose applications include electrophotography, switching, and memory elements.

  11. Amorphous silicon based radiation detectors

    SciTech Connect

    Perez-Mendez, V.; Cho, G.; Drewery, J.; Jing, T.; Kaplan, S.N.; Qureshi, S.; Wildermuth, D. ); Fujieda, I.; Street, R.A. )

    1991-07-01

    We describe the characteristics of thin(1 {mu}m) and thick (>30{mu}m) hydrogenated amorphous silicon p-i-n diodes which are optimized for detecting and recording the spatial distribution of charged particles, x-rays and {gamma} rays. For x-ray, {gamma} ray, and charged particle detection we can use thin p-i-n photosensitive diode arrays coupled to evaporated layers of suitable scintillators. For direct detection of charged particles with high resistance to radiation damage, we use the thick p-i-n diode arrays. 13 refs., 7 figs.

  12. Preparation of amorphous sulfide sieves

    DOEpatents

    Siadati, Mohammad H.; Alonso, Gabriel; Chianelli, Russell R.

    2006-11-07

    The present invention involves methods and compositions for synthesizing catalysts/porous materials. In some embodiments, the resulting materials are amorphous sulfide sieves that can be mass-produced for a variety of uses. In some embodiments, methods of the invention concern any suitable precursor (such as thiomolybdate salt) that is exposed to a high pressure pre-compaction, if need be. For instance, in some cases the final bulk shape (but highly porous) may be same as the original bulk shape. The compacted/uncompacted precursor is then subjected to an open-flow hot isostatic pressing, which causes the precursor to decompose and convert to a highly porous material/catalyst.

  13. Structural study of amorphous polyaniline

    NASA Astrophysics Data System (ADS)

    Laridjani, M.; Pouget, J. P.; MacDiarmid, A. G.; Epstein, A. J.

    1992-06-01

    Many materials, especially polymers, have a substantial volume fraction with no long range crystalline order. Through these regions are often termed amorphous, they frequently have a specific local order. We describe and use here a method, base on a non-energy dispersive X-ray diffraction technique, to obtain good quality interference functions and, by Fourier transform, radial distribution functions of the amorphous structure of polymers. We apply this approach to members of a family of electronic polymers of current interest : polyaniline emeraldine bases. We show that the local order exhibits significant differences in type I and type II materials, precipitated as salt and base respectively. These studies demonstrate the importance of sample preparation in evaluating the physical properties of polyaniline, and provide a structural origin for memory effects observed in the doping-dedoping processes. Beaucoup de matériaux, spécialement les polymères, ont une importante fraction de leur volume sans ordre cristallin à longue portée. Bien que ces régions soient souvent appelées amorphes, elles présentent fréquemment un ordre local caractéristique. Nous décrivons et utilisons dans ce papier une méthode, basée sur une technique de diffraction de rayons X non dispersive en énergie, pour obtenir des fonctions d'interférence de bonne qualité et, par transformée de Fourier, la fonction de distribution radiale des polymères amorphes. Nous appliquons cette technique à plusieurs éléments d'une même famille de polymères électroniques d'intérêt actuel : les polyanilines éméraldine bases. Nous montrons que l'ordre local présente d'appréciables différences dans les matériaux de type I et II, préparés respectivement sous forme de sel et de base. Cette étude démontre l'importance des conditions de préparation sur les propriétés physiques du polyaniline et donne une base structurale aux effets observés dans les processus de dopage-dédopage de

  14. Contact versus non-contact ablation of the artificial enamel caries by Er:YAG and CTH:YAG laser radiation

    NASA Astrophysics Data System (ADS)

    Dostálová, Tat'jana; Jelínková, Helena; Å ulc, Jan; Němec, Michal; Bučková, Michaela; Kašparová, Magdalena; Miyagi, Mitsunobu

    The aim of study is to compare the ablation effect of contact and non-contact interaction of Er:YAG and CTH:YAG laser radiation with artificial enamel caries lesion. The artificial caries was prepared in intact teeth to simulate demineralized surface and the laser radiation was applied. Contact and non-contact ablation was compared. Two laser systems Er:YAG 2.94 μm and CTH:YAG 2.1 μm were used. The enamel artificial caries were gently removed by laser radiation and flow Sonic fill composite resin was inserted. Scanning electron microscope was use to evaluate the enamel surface.

  15. Effect of solubility YAG:Nd nanocrystals in glass matrix

    SciTech Connect

    Szysiak, A.; Stepien, R.; Ryba-Romanowski, W.; Solarz, P.; Mirkowska, M.; Lipinska, L.; Pajaczkowska, A.

    2011-10-15

    Highlights: {yields} The mixture of borate glass powder and YAG:5%Nd{sup 3+} nanocrystals was prepared. {yields} The samples were formed into pallets and annealed at different temperatures. {yields} The luminescence properties of composites depends crucially on annealing temperature. -- Abstract: The nanocomposites of Y{sub 3}Al{sub 5}O{sub 12}:Nd{sup 3+} (YAG:Nd) incorporated in borate glass were obtained. The single phase of YAG:Nd nanocrystals were obtained by sol-gel method. The borate glass was melted first and ground up then mixed with the nanocrystals. The samples were formed into pellets under pressure and were annealed in temperatures from the range 550-800 {sup o}C. The X-ray diffraction patterns show that together with increasing the temperature the contribution of Y{sub 3}Al{sub 5}O{sub 12} phase decreases and the new YBa{sub 3}B{sub 9}O{sub 19} phase is observed. The luminescence measurements indicates that the band structures and distribution of band intensities of glass-YAG:Nd nanocrystal composites depends crucially on annealing temperature.

  16. Er:YAG laser dentistry in special needs patients

    PubMed Central

    Fornaini, Carlo; Clini, Fabio; Fontana, Matteo; Cella, Luigi; Oppici, Aldo

    2015-01-01

    Objective: Between a quarter and a third of adults with intellectual disability is estimated to have dental anxiety. Unpleasant stimuli, such as the injection of local anaesthesia or the noise and vibration of rotary instruments, may provoke anxiety and subsequent low compliance until the opposition to the treatment. The use of Er:YAG laser in conservative dentistry had a great development in these last years thank to new devices and also to their advantages when compared to the conventional instruments. The aim of this clinical study was to show the advantages of the Er:YAG laser in the conservative treatment of Special Care patients. Methods: Four cases are here described to show the Er:YAG laser use in our Unit on special needs patients. Results and conclusions: Based on the experience gained on conservative laser-assisted treatments performed in a time of 5 years at our Dentistry, Special Needs and Maxillo-Facial Surgery Unit we may affirm that Er:YAG laser may be considered as a good way to improve the cooperation, to reduce anxiety related to rotating instruments and to reach better results with equal or shorter operating times. PMID:26557733

  17. Erbium:YAG laser-assisted cataract surgery.

    PubMed

    Stevens, G; Long, B; Hamann, J M; Allen, R C

    1998-03-01

    To assess the safety and efficacy of erbium:YAG laser-assisted cataract removal. A total of 15 patients underwent cataractous lens removal. All the patients had a visual acuity of 20/50 or worse secondary to senile cataract. The endothelial cell count was calculated preoperatively and at 6 weeks postoperatively. A 2.94-micron-wavelength erbium: YAG laser with a zirconium-fluoride fiber optic and silica tip was used to fracture and emulsify the nucleus. The erbium:YAG laser was chosen due to its high absorption in water, a primary component of a cataractous lens. The postoperative visual acuity was 20/30 or better in all the eyes that were treated with surgery. The endothelial cell loss at 3 months was 0% to 10%. No laser-related complications were noted. A conversion to an ultrasound surgical technique was utilized in six cases. Vitreous loss occurred in one case due to the posterior extension of an anterior capsulotomy tear. This study demonstrated the ability of an erbium:YAG laser system to safely and effectively emulsify the lens nucleus. Laser-assisted cataract surgery is a promising new clinical procedure.

  18. Minimally invasive scoliosis treatment with a Ho:YAG laser

    NASA Astrophysics Data System (ADS)

    Rumpf, Christian G.; Lang, Robert D.; Goetz, Marcus H.

    2000-11-01

    Today most surgical treatment of spinal deformations is concentrated on invasive mechanical techniques with long operation times and major effects on the patient's mobility. The proposed minimally invasive technique using laser light for tissue ablation offers a possibility of gentle scoliosis treatment. It is thought that an early removal of the epiphysial growth zone on the convex side over several vertebrae results in a straightening of the spine. In a first evaluation, four different laser systems including argon ion, Nd:YAG (Q-switched), Nd:YAG (cw), and Ho:YAG laser were compared with respect to thermal damage to adjacent tissue, ablation rates, efficiency and laser handling. For in-vivo investigation, fresh lamb spine was used. Comparison showed that the Ho:YAG laser is the most appropriate laser for the given goal, providing efficient photoablation with moderate thermal effects on the adjacent tissue. In a second step the proposed minimally invasive operation technique was performed in in-vivo experiments on young foxhounds using 3D- thoracoscopic operation techniques. During these operations temperature mapping was done using fiber-optic fluorescent probes. After 12 months of normal growth the animals were sacrificed and x-ray as well as MRI was performed on the spine. First results show a positive effect of scoliotic growth in two cases. Being able to produce a scoliosis by hemiepiphysiodesis on the vertebra, It is thought that this technique is successful for a straightening of the spine on patients with scoliosis.

  19. Optimal pumping for eye-safe Er:YAG laser

    NASA Astrophysics Data System (ADS)

    Buchenkov, Vyacheslav A.; Polyakov, Vadim M.; Rodionov, Andrey Y.; Kovalev, Anton V.

    2016-04-01

    We report on theoretical investigation of quasi-three level Er:YAG laser. We propose a numerical model of the laser design with side pump by 1471 nm laser diodes. The model describes the dynamical propagation of the pump in the cavity and the kinetic parameters of the active medium.

  20. Tunable, diode side-pumped Er:YAG laser

    DOEpatents

    Hamilton, C.E.; Furu, L.H.

    1997-04-22

    A discrete-element Er:YAG laser, side pumped by a 220 Watt peak-power InGaAs diode array, generates >500 mWatts at 2.94 {micro}m, and is tunable over a 6 nm range near about 2.936 {micro}m. The oscillator is a plano-concave resonator consisting of a concave high reflector, a flat output coupler, a Er:YAG crystal and a YAG intracavity etalon, which serves as the tuning element. The cavity length is variable from 3 cm to 4 cm. The oscillator uses total internal reflection in the Er:YAG crystal to allow efficient coupling of the diode emission into the resonating modes of the oscillator. With the tuning element removed, the oscillator produces up to 1.3 Watts of average power at 2.94 {micro}m. The duty factor of the laser is 6.5% and the repetition rate is variable up to 1 kHz. This laser is useful for tuning to an atmospheric transmission window at 2.935 {micro}m (air wavelength). The laser is also useful as a spectroscopic tool because it can access several infrared water vapor transitions, as well as transitions in organic compounds. Other uses include medical applications (e.g., for tissue ablation and uses with fiber optic laser scalpels) and as part of industrial effluent monitoring systems. 4 figs.

  1. Tunable, diode side-pumped Er: YAG laser

    DOEpatents

    Hamilton, Charles E.; Furu, Laurence H.

    1997-01-01

    A discrete-element Er:YAG laser, side pumped by a 220 Watt peak-power InGaAs diode array, generates >500 mWatts at 2.94 .mu.m, and is tunable over a 6 nm range near about 2.936 .mu.m. The oscillator is a plano-concave resonator consisting of a concave high reflector, a flat output coupler, a Er:YAG crystal and a YAG intracavity etalon, which serves as the tuning element. The cavity length is variable from 3 cm to 4 cm. The oscillator uses total internal reflection in the Er:YAG crystal to allow efficient coupling of the diode emission into the resonating modes of the oscillator. With the tuning element removed, the oscillator produces up to 1.3 Watts of average power at 2.94 .mu.m. The duty factor of the laser is 6.5% and the repetition rate is variable up to 1 kHz. This laser is useful for tuning to an atmospheric transmission window at 2.935 .mu.m (air wavelength). The laser is also useful as a spectroscopic tool because it can access several infrared water vapor transitions, as well as transitions in organic compounds. Other uses include medical applications (e.g., for tissue ablation and uses with fiber optic laser scalpels) and as part of industrial effluent monitoring systems.

  2. Performance of Ho:YAG as a function of temperature

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Gettemy, Donald J.

    1990-01-01

    The performance of two multiply doped Ho:YAG lasers has been characterized as a function of the laser rod temperature. From the experimental results, the dependence of the slope efficiency and threshold on temperature has been extracted. Threshold can be correlated with the occupation of the lower laser level. Implications on the optimum operating temperature are discussed.

  3. Performance of Ho:YAG as a function of temperature

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Gettemy, Donald J.

    1990-01-01

    The performance of two multiply doped Ho:YAG lasers has been characterized as a function of the laser rod temperature. From the experimental results, the dependence of the slope efficiency and threshold on temperature has been extracted. Threshold can be correlated with the occupation of the lower laser level. Implications on the optimum operating temperature are discussed.

  4. Innovative high-power CW Yb:YAG cryogenic laser

    NASA Astrophysics Data System (ADS)

    Brown, D. C.; Singley, J. M.; Yager, E.; Kuper, J. W.; Lotito, B. J.; Bennett, L. L.

    2007-04-01

    In this paper we discuss a CW Yb:YAG cryogenic laser program that has resulted in the design and demonstration of a novel high power laser. Cryogenically-cooled crystalline solid-state lasers, and Yb:YAG lasers in particular, are attractive sources of scalable CW output power with very high wallplug efficiency and excellent beam-quality that is independent of the output power. This laser consists of a distributed array of seven highly-doped thin Yb:YAG-sapphire disks in a folded multiple-Z resonator. Individual disks are pumped from opposite sides using fiber-coupled ~ 30W 940nm pump diodes. The laser system we have constructed produces a near-diffraction-limited TEM 00 output beam with the aid of an active conduction-cooling design. In addition, the device can be scaled to very high average power in a MOPA configuration, by increasing the number and diameter of the thin disks, and by increasing the power of the pump diodes with only minor modifications to the current design. The thermal and optical benefits of cryogenically-cooled solid-state lasers will be reviewed, scalability of our Yb:YAG cryogenic laser design will be discussed, and we will present experimental results including output power, slope and optical-optical efficiencies, and beam-quality.

  5. Innovative high-power CW Yb:YAG cryogenic laser

    NASA Astrophysics Data System (ADS)

    Brown, D. C.; Singley, J. M.; Yager, E.; Kuper, J. W.; Lotito, B. J.; Bennett, L. L.

    2007-02-01

    In this paper we discuss a CW Yb:YAG cryogenic laser program that has resulted in the design and demonstration of a novel high power laser. Cryogenically-cooled crystalline solid-state lasers, and Yb:YAG lasers in particular, are attractive sources of scalable CW output power with very high wallplug efficiency and excellent beam-quality that is independent of the output power. This laser consists of a distributed array of seven highly-doped thin Yb:YAG-sapphire disks in a folded multiple-Z resonator. Individual disks are pumped from opposite sides using fiber-coupled ~ 30W 940nm pump diodes. The laser system we have constructed produces a near-diffraction-limited TEM 00 output beam with the aid of an active conduction-cooling design. In addition, the device can be scaled to very high average power in a MOPA configuration, by increasing the number and diameter of the thin disks, and by increasing the power of the pump diodes with only minor modifications to the current design. The thermal and optical benefits of cryogenically-cooled solid-state lasers will be reviewed, scalability of our Yb:YAG cryogenic laser design will be discussed, and we will present experimental results including output power, slope and optical-optical efficiencies, and beam-quality.

  6. Er:YAG clinical results on hard tissue: phase II

    NASA Astrophysics Data System (ADS)

    Cozean, Colette D.; Powell, G. L.

    1998-04-01

    Objective: In Phase I, we demonstrated the safety and efficacy of the pulsed 2.94 micron Er:YAG laser for caries removal, cavity preparation and laser etching utilizing in vivo teeth scheduled for removal to quantitatively verify the safety of the product for up to one year following treatment. Phase II was a continuation of this study evaluating in vivo teeth to verify the safety and efficacy of the Er:YAG in a long-term follow-up study. Methods: We randomly divided the patients into two groups: a laser group and a control group, which employed the high speed drill. The investigators rated clinical efficacy by several criteria, evaluated pain and measured pulpal vitality up to two years following treatment. This phase consisted of 512 procedures that made up the laser group and 357 procedures that made up the control group. Conclusions: The results from this phase showed that the Er:YAG laser was able to perform as well as, if not better than, the drill in caries removal, cavity preparation, and acid etching alone. Use of the laser virtually eliminated the need for anesthesia. The Er:YAG laser is safe and efficacious for removal of caries, cavity preparation and etching prior to acid etching.

  7. Bright YAG:Ce Nanorod Phosphors Prepared via a Partial Wet Chemical Route and Biolabeling Applications.

    PubMed

    Guo, Daidong; Ma, Baojin; Zhao, Lili; Qiu, Jichuan; Liu, Wei; Sang, Yuanhua; Claverie, Jerome; Liu, Hong

    2016-05-18

    Cerium-doped yttrium aluminum garnet (YAG:Ce) nanorods were prepared via a partial wet chemical route followed by a calcination process by using Al2O3 nanorods as both templates and the reactant. These novel well-crystallized YAG:Ce phosphors with a 200-300 nm diameter and a 2-3 μm length have a high specific surface area while being virtually devoid of surface defects. The YAG:Ce nanorod phosphors possess good luminescent properties compared with granular YAG:Ce phosphors. Photoluminescence quantum yields of YAG:Ce nanorod phosphors are higher than those of granular ones. The YAG:Ce nanorod phosphors exhibit two luminescent decay times due to their unique morphology. The YAG:Ce nanorods exhibited good cytocompatibility with bone marrow mesenchymal stem cells and can be used as biolabel nanoparticles in bioimaging.

  8. The Sm:YAG primary fluorescence pressure scale

    NASA Astrophysics Data System (ADS)

    Trots, Dmytro M.; Kurnosov, Alexander; Ballaran, Tiziana Boffa; Tkachev, Sergey; Zhuravlev, Kirill; Prakapenka, Vitali; Berkowski, Marek; Frost, Daniel J.

    2013-11-01

    pressure determinations involve the measurement of pressure without recourse to secondary standard materials. These measurements are essential for ensuring the accuracy of pressures measured in gasketed high-pressure devices. In this study, the wavelength of optical fluorescence bands and the density of single crystal Sm-doped yttrium aluminum garnet Y3Al5O12 (Sm:YAG) have been calibrated as a primary pressure scale up to 58 GPa. Absolute pressures were obtained by integrating the bulk modulus determined via Brillouin spectroscopy with respect to volumes measured simultaneously by X-ray diffraction. A third-order Birch-Murnaghan equation of state of Sm:YAG yields V0 = 1735.15(26) Å3, KT0 = 185(1.5) GPa, and K` = 4.18(5). The accompanied pressure-induced shifts of the fluorescence lines Y1 and Y2 of Sm:YAG were calibrated to the primary pressure, thus creating a highly accurate fluorescence pressure scale. These shifts are described as P = (A/B) * {[1 + (Δλ/λ0)]B - 1} with A = 2089.91(23.04), B = -4.43(1.07) for Y1, and A = 2578.22(48.70), B = -15.38(1.62) for Y2 bands, where ∆λ = λ - λ0, λ and λ0 are wavelengths in nanometer at pressure and ambient conditions. The sensitivity in the pressure determination of the Sm:YAG fluorescence shift is 0.32 nm/GPa, which is identical to that of the ruby scale. Sm:YAG can be considered elastically isotropic up to 58 GPa, implying insensitivity of the determined pressure to the crystallographic orientation under nonhydrostatic or quasi-hydrostatic conditions. The Sm:YAG fluorescence shift is apparently also independent of crystallographic orientation, in contrast to that of ruby. Since the Y fluorescence band of Sm:YAG is insensitive to temperature changes, this material is highly suitable for the measurement of pressure at elevated temperatures.

  9. Is Mg-stabilized amorphous calcium carbonate a homogeneous mixture of amorphous magnesium carbonate and amorphous calcium carbonate?

    PubMed

    Yang, Sheng-Yu; Chang, Hsun-Hui; Lin, Cang-Jie; Huang, Shing-Jong; Chan, Jerry C C

    2016-10-04

    We find two types of carbonate ions in Mg stabilized amorphous calcium carbonate (Mg-ACC), whose short-range orders are identical to those of ACC and amorphous magnesium carbonate (AMC). Mg-ACC comprises a homogeneous mixture of the nano-clusters of ACC and AMC. Their relative amount varies systematically at different pH.

  10. Laser surface treatment of amorphous metals

    NASA Astrophysics Data System (ADS)

    Katakam, Shravana K.

    Amorphous materials are used as soft magnetic materials and also as surface coatings to improve the surface properties. Furthermore, the nanocrystalline materials derived from their amorphous precursors show superior soft magnetic properties than amorphous counter parts for transformer core applications. In the present work, laser based processing of amorphous materials will be presented. Conventionally, the nanocrystalline materials are synthesized by furnace heat treatment of amorphous precursors. Fe-based amorphous/nanocrystalline materials due to their low cost and superior magnetic properties are the most widely used soft magnetic materials. However, achieving nanocrystalline microstructure in Fe-Si-B ternary system becomes very difficult owing its rapid growth rate at higher temperatures and sluggish diffusion at low temperature annealing. Hence, nanocrystallization in this system is achieved by using alloying additions (Cu and Nb) in the ternary Fe-Si-B system. Thus, increasing the cost and also resulting in reduction of saturation magnetization. laser processing technique is used to achieve extremely fine nanocrystalline microstructure in Fe-Si-B amorphous precursor. Microstructure-magnetic Property-laser processing co-relationship has been established for Fe-Si-B ternary system using analytical techniques. Laser processing improved the magnetic properties with significant increase in saturation magnetization and near zero coercivity values. Amorphous materials exhibit excellent corrosion resistance by virtue of their atomic structure. Fe-based amorphous materials are economical and due to their ease of processing are of potential interest to synthesize as coatings materials for wear and corrosion resistance applications. Fe-Cr-Mo-Y-C-B amorphous system was used to develop thick coatings on 4130 Steel substrate and the corrosion resistance of the amorphous coatings was improved. It is also shown that the mode of corrosion depends on the laser processing

  11. Tissue damage by laser radiation: an in vitro comparison between Tm:YAG and Ho:YAG laser on a porcine kidney model.

    PubMed

    Huusmann, Stephan; Wolters, Mathias; Kramer, Mario W; Bach, Thorsten; Teichmann, Heinrich-Otto; Eing, Andreas; Bardosi, Sebastian; Herrmann, Thomas R W

    2016-01-01

    The understanding of tissue damage by laser radiation is very important for the safety in the application of surgical lasers. The objective of this study is to evaluate cutting, vaporization and coagulation properties of the 2 µm Tm:YAG laser (LISA Laser Products OHG, GER) in comparison to the 2.1 µm Ho:YAG laser (Coherent Medical Group, USA) at different laser power settings in an in vitro model of freshly harvested porcine kidneys. Laser radiation of both laser generators was delivered by using a laser fiber with an optical core diameter of 550 µm (RigiFib, LISA Laser GER). Freshly harvested porcine kidneys were used as tissue model. Experiments were either performed in ambient air or in aqueous saline. The Tm:YAG laser was adjusted to 5 W for low and 120 W for the high power setting. The Ho:YAG laser was adjusted to 0.5 J and 10 Hz (5 W average power) for low power setting and to 2.0 J and 40 Hz (80 W average power) for high power setting, accordingly. The specimens of the cutting experiments were fixed in 4 % formalin, embedded in paraffin and stained with Toluidin blue. The laser damage zone was measured under microscope as the main evaluation criteria. Laser damage zone consists of an outer coagulation zone plus a further necrotic zone. In the ambient air experiments the laser damage zone for the low power setting was 745 ± 119 µm for the Tm:YAG and 614 ± 187 µm for the Ho:YAG laser. On the high power setting, the damage zone was 760 ± 167 µm for Tm:YAG and 715 ± 142 µm for Ho:YAG. The incision depth in ambient air on the low power setting was 346 ± 199 µm for Tm:YAG, 118 ± 119 µm for Ho:YAG. On the high power setting incision depth was 5083 ± 144 µm (Tm:YAG) and 1126 ± 383 µm (Ho:YAG) respectively. In the saline solution experiments, the laser damage zone was 550 ± 137 µm (Tm:YAG) versus 447 ± 65 µm (Ho:YAG), on the low power setting and 653 ± 137 µm (Tm:YAG) versus 677 ± 134 µm (Ho:YAG

  12. Er:YAG and Nd:YAG laser in treatment of patients with contraindications of conventional dental and maxillofacial surgery

    NASA Astrophysics Data System (ADS)

    Smucler, Roman; Mazanek, Jiri

    2000-03-01

    In clinical praxis we must treat patients with some relative or absolute contraindications every day. Need of hospitalization, antibiotics, hemostyptics and complex examinations makes dentoalveolar and maxillofacial surgery in those cases quite expensive. Combination of Nd:YAG and Er:YAG laser gives us new possibilities. We can help some untreatable patients or transfer care from hospital to dental office. We have been trying to solve contraindications for laser therapy five years. In the center of our work are disorders of blood coagulation, immunity and metabolism. Nd:YAG laser is very useful in coagulation and vaporization of dental gum hypertrophies, benign and malign tumors in case of chronic anticoagulation therapy and immunosupress / in combination for example- after heart transplantation /. Special chapter is the care of patients with disseminated tumors. Er:YAG laser large solve big lesions because of minimal invasivity of course but for small benign tumors are recidives is ideal. Better and quicker healing make new standard of patients' cooperation. Generally fashionable and more comfortable laser treatment minimize need of general anesthesia. After five years we use complex laser therapy in our routine. Aim of our new work is to find ideal combination of cutting lasers to minimize classical complications of laser surgery / carbonization, long and secondary healing /.

  13. FT-Raman spectroscopic characterization of enamel surfaces irradiated with Nd:YAG and Er:YAG lasers

    PubMed Central

    Shahabi, Sima; Fekrazad, Reza; Johari, Maryam; Chiniforoush, Nasim; Rezaei, Yashar

    2016-01-01

    Background. Despite recent advances in dental caries prevention, caries is common and remains a serious health problem. Laser irradiation is one of the most common methods in preventive measures in recent years. Raman spectroscopy technique is utilized to study the microcrystalline structure of dental enamel. In this study, FT-Raman spectroscopy was used to evaluate chemical changes in enamel structure irradiated with Nd:YAG and Er:YAG lasers. Methods. We used 15 freshly-extracted, non-carious, human molars that were treated as follows: No treatment was carried out in group A (control group); Group B was irradiated with Er:YAG laser for 10 seconds under air and water spray; and Group C was irradiated with Nd:YAG laser for 10 seconds under air and water spray. After treatment, the samples were analyzed by FT-Raman spectroscopy. Results. The carbonate content evaluation with regard to the integrated area under the curve (1065/960 cm–1) exhibited a significant reduction in its ratio in groups B and C. The organic content (2935/960 cm-1) area exhibited a significant decrease after laser irradiation in group B and C. Conclusion. The results showed that the mineral and organic matrices of enamel structure were affected by laser irradiation; therefore, it might be a suitable method for caries prevention. PMID:28096945

  14. Effects of Er:YAG and Nd:YAG laser irradiation on the permeability of instrumented root canal walls

    NASA Astrophysics Data System (ADS)

    Brugnera, Aldo, Jr.; Zanin, Fatima A. A.; Barbin, Eduardo L.; Emboava Spano, Julio C.; Santana da Silva, Reginaldo; Pecora, Jesus D.

    2002-06-01

    The aim of this study was to evaluate the effect of Er:YAG and Nd:YAG laser on radicular dentine permeability when using distilled and deionized water and 1% sodium hypochlorite as irrigating solutions. Thirty human maxillary canines obtained from laboratory stock and conserved in 0.1% thymol until use were divided randomly into six groups of five teeth each. The root canals were instrumented with K files and the step-back technique. The surgical diameter was achieved 4 files above the original anatomical diameter. Group I, the teeth were irrigated with distilled and deionized water; Group II, the teeth were irrigated with 1% sodium hypochlorite, Group II the teeth were irrigated with distilled and deionized water and then Er:YAG laser was applied with 140mJ, 15Hz, 300 pulses and 42J; group 4 the teeth were irrigated with 1% sodium hypochlorite and Er:YAG laser was applied in the same parameters as Group III, Group V, the teeth received irrigation with distilled and deionized water and Nd:YAG laser application with 150mJ, 15Hz, 2,25W and Group VI the teeth were irrigated with 1% sodium hypochlorite and Nd:YAG laser was applied with the same parameters as Group V. During laser application the teeth were always filled with irrigating solution. The fiber optic tip was introduced until the apex and the laser was activated. The tip was withdrawn gently with helicoidally movement from the apex until the pulp chamber. After preparation the teeth were immersed in 10% copper sulfate for 30 minutes, in vacuum for the first 5 minutes. The teeth were then placed in a 1% rubianic acid alcohol solution for the same periodsin solution and in vacuum as above. Upon completion of this reaction the teeth were sectioned transversally, in 150micrometers slices, and sanded, washed, dehydrated, cleared and mounted on glass slides for microscopic examination. The quantification of the penetration of copper ions was done by morphmetric analysis with a 400-point grid. The data was submitted

  15. Fluorination of amorphous thin-film materials with xenon fluoride

    DOEpatents

    Weil, R.B.

    1987-05-01

    A method is disclosed for producing fluorine-containing amorphous semiconductor material, preferably comprising amorphous silicon. The method includes depositing amorphous thin-film material onto a substrate while introducing xenon fluoride during the film deposition process.

  16. Fluorination of amorphous thin-film materials with xenon fluoride

    DOEpatents

    Weil, Raoul B.

    1988-01-01

    A method is disclosed for producing fluorine-containing amorphous semiconductor material, preferably comprising amorphous silicon. The method includes depositing amorphous thin-film material onto a substrate while introducing xenon fluoride during the film deposition process.

  17. Imprinting bulk amorphous alloy at room temperature

    DOE PAGES

    Kim, Song-Yi; Park, Eun-Soo; Ott, Ryan T.; ...

    2015-11-13

    We present investigations on the plastic deformation behavior of a brittle bulk amorphous alloy by simple uniaxial compressive loading at room temperature. A patterning is possible by cold-plastic forming of the typically brittle Hf-based bulk amorphous alloy through controlling homogenous flow without the need for thermal energy or shaping at elevated temperatures. The experimental evidence suggests that there is an inconsistency between macroscopic plasticity and deformability of an amorphous alloy. Moreover, imprinting of specific geometrical features on Cu foil and Zr-based metallic glass is represented by using the patterned bulk amorphous alloy as a die. These results demonstrate the abilitymore » of amorphous alloys or metallic glasses to precisely replicate patterning features onto both conventional metals and the other amorphous alloys. In conclusion, our work presents an avenue for avoiding the embrittlement of amorphous alloys associated with thermoplastic forming and yields new insight the forming application of bulk amorphous alloys at room temperature without using heat treatment.« less

  18. Amorphization of solids irradiated by fast neutrons

    NASA Astrophysics Data System (ADS)

    Parkhomenko, V.; Dubinin, S.; Teploukhov, S.; Goshchitskii, B.

    2000-03-01

    The diffraction patterns of amorphous solids produced by both a conventional technique and fast neutron irradiation were systematized. It is shown for the first time that neutron radiation-modified solids belong to the group of amorphous substances of a distortion type.

  19. Evolution of the structure of amorphous ice: from low-density amorphous through high-density amorphous to very high-density amorphous ice.

    PubMed

    Martonák, R; Donadio, D; Parrinello, M

    2005-04-01

    We report results of molecular dynamics simulations of amorphous ice for pressures up to 22.5 kbar. The high-density amorphous ice (HDA) as prepared by pressure-induced amorphization of I(h) ice at T=80 K is annealed to T=170 K at various pressures to allow for relaxation. Upon increase of pressure, relaxed amorphous ice undergoes a pronounced change of structure, ranging from the low-density amorphous ice at p=0, through a continuum of HDA states to the limiting very high-density amorphous ice (VHDA) regime above 10 kbar. The main part of the overall structural change takes place within the HDA megabasin, which includes a variety of structures with quite different local and medium-range order as well as network topology and spans a broad range of densities. The VHDA represents the limit to densification by adapting the hydrogen-bonded network topology, without creating interpenetrating networks. The connection between structure and metastability of various forms upon decompression and heating is studied and discussed. We also discuss the analogy with amorphous and crystalline silica. Finally, some conclusions concerning the relation between amorphous ice and supercooled water are drawn.

  20. Electron beam recrystallization of amorphous semiconductor materials

    NASA Technical Reports Server (NTRS)

    Evans, J. C., Jr.

    1968-01-01

    Nucleation and growth of crystalline films of silicon, germanium, and cadmium sulfide on substrates of plastic and glass were investigated. Amorphous films of germanium, silicon, and cadmium sulfide on amorphous substrates of glass and plastic were converted to the crystalline condition by electron bombardment.

  1. Electron tunnelling into amorphous germanium and silicon.

    NASA Technical Reports Server (NTRS)

    Smith, C. W.; Clark, A. H.

    1972-01-01

    Measurements of tunnel conductance versus bias, capacitance versus bias, and internal photoemission were made in the systems aluminum-oxide-amorphous germanium and aluminium-oxide-amorphous silicon. A function was extracted which expresses the deviation of these systems from the aluminium-oxide-aluminium system.

  2. Method of making amorphous metal composites

    DOEpatents

    Byrne, Martin A.; Lupinski, John H.

    1982-01-01

    The process comprises placing an amorphous metal in particulate form and a low molecular weight (e.g., 1000-5000) thermosetting polymer binder powder into a container, mixing these materials, and applying heat and pressure to convert the mixture into an amorphous metal composite.

  3. Co amorphous systems: A product development perspective.

    PubMed

    Chavan, Rahul B; Thipparaboina, Rajesh; Kumar, Dinesh; Shastri, Nalini R

    2016-12-30

    Solubility is one of the major problems associated with most of the new chemical entities that can be reasonably addressed by drug amorphization. However, being a high-energy form, it usually tends to re-crystallize, necessitating new formulation strategies to stabilize amorphous drugs. Polymeric amorphous solid dispersion (PASD) is one of the widely investigated strategies to stabilize amorphous drug, with major limitations like limited polymer solubility and hygroscopicity. Co amorphous system (CAM), a new entrant in amorphous arena is a promising alternative to PASD. CAMs are multi component single phase amorphous solid systems made up of two or more small molecules that may be a combination of drugs or drug and excipients. Excipients explored for CAM preparation include amino acids, carboxylic acids, nicotinamide and saccharine. Advantages offered by CAM include improved aqueous solubility and physical stability of amorphous drug, with a potential to improve therapeutic efficacy. This review attempts to address different aspects in the development of CAM as drug products. Criterion for co-former selection, various methods involved in CAM preparation, characterization tools, stability, scale up and regulatory requirements for the CAM product development are discussed.

  4. Neutron irradiation induced amorphization of silicon carbide

    SciTech Connect

    Snead, L.L.; Hay, J.C.

    1998-09-01

    This paper provides the first known observation of silicon carbide fully amorphized under neutron irradiation. Both high purity single crystal hcp and high purity, highly faulted (cubic) chemically vapor deposited (CVD) SiC were irradiated at approximately 60 C to a total fast neutron fluence of 2.6 {times} 10{sup 25} n/m{sup 2}. Amorphization was seen in both materials, as evidenced by TEM, electron diffraction, and x-ray diffraction techniques. Physical properties for the amorphized single crystal material are reported including large changes in density ({minus}10.8%), elastic modulus as measured using a nanoindentation technique ({minus}45%), hardness as measured by nanoindentation ({minus}45%), and standard Vickers hardness ({minus}24%). Similar property changes are observed for the critical temperature for amorphization at this neutron dose and flux, above which amorphization is not possible, is estimated to be greater than 130 C.

  5. Structure, thermodynamics, and crystallization of amorphous hafnia

    SciTech Connect

    Luo, Xuhui; Demkov, Alexander A.

    2015-09-28

    We investigate theoretically amorphous hafnia using the first principles melt and quench method. We identify two types of amorphous structures of hafnia. Type I and type II are related to tetragonal and monoclinic hafnia, respectively. We find type II structure to show stronger disorder than type I. Using the phonon density of states, we calculate the specific heat capacity for type II amorphous hafnia. Using the nudged elastic band method, we show that the averaged transition barrier between the type II amorphous hafnia and monoclinic phase is approximately 0.09 eV/HfO{sub 2}. The crystallization temperature is estimated to be 421 K. The calculations suggest an explanation for the low thermal stability of amorphous hafnia.

  6. Amorphization of sugar hydrates upon milling.

    PubMed

    Willart, J F; Dujardin, N; Dudognon, E; Danède, F; Descamps, M

    2010-07-19

    The possibility to amorphize anhydrous crystalline sugars, like lactose, trehalose and glucose, by mechanical milling was previously reported. We test here the possibility to amorphize the corresponding crystalline hydrates: lactose monohydrate, trehalose dihydrate and glucose monohydrate using fully identical milling procedures. The results show that only the first hydrate amorphizes while the other two remain structurally invariant. These different behaviours are attributed to the plasticizing effect of the structural water molecules which can decrease the glass transition temperature below the milling temperature. The results reveal clearly the fundamental role of the glass transition in the solid-state amorphization process induced by milling, and they also explain why crystalline hydrates are systematically more difficult to amorphize by milling than their anhydrous counterpart. The investigations have been performed by differential scanning calorimetry and powder X-ray diffraction.

  7. Compensated amorphous-silicon solar cell

    DOEpatents

    Devaud, G.

    1982-06-21

    An amorphous silicon solar cell including an electrically conductive substrate, a layer of glow discharge deposited hydrogenated amorphous silicon having regions of differing conductivity with at least one region of intrinsic hydrogenated amorphous silicon. The layer of hydrogenated amorphous silicon has opposed first and second major surfaces where the first major surface contacts the elecrically conductive substrate and an electrode for electrically contacting the second major surface. The intrinsic hydrogenated amorphous silicon region is deposited in a glow discharge with an atmosphere which includes not less than about 0.02 atom percent mono-atomic boron. An improved N.I.P. solar cell is disclosed using a BF/sub 3/ doped intrinsic layer.

  8. Role of diffusion in amorphous-phase formation and crystallization of amorphous Ni--Zr

    SciTech Connect

    Barbour, J.C.; de Reus, R.; Denier van der Gon, A.W.; Saris, F.W.

    1987-03-01

    The Ni--Zr system is examined as a representative system for the formation of an amorphous phase by diffusion and for the crystallization of an amorphous phase by diffusion. High-resolution electron microscopy (HREM) is used to show that the amorphous phase grows by bulk diffusion through the amorphous material rather than by short-circuit diffusion. Also, the HREM shows that the amorphous phase formed by diffusion appears to be the same as the vapor-deposited amorphous phase. A correlation between crystallization temperatures (T/sub x/) and the enthalpy of large-atom hole formation is given. This correlation predicts values of T/sub x/ that are lower than those predicted from the small-atom hole-formation model. The difference in hole-formation enthalpies for the large and small atoms is given as a criterion for amorphous-phase formation via diffusion.

  9. Nanostructuring of GeTiO amorphous films by pulsed laser irradiation

    PubMed Central

    Teodorescu, Valentin Serban; Ghica, Cornel; Maraloiu, Adrian Valentin; Vlaicu, Mihai; Kuncser, Andrei; Stavarache, Ionel; Lepadatu, Ana M; Scarisoreanu, Nicu Doinel; Andrei, Andreea; Ion, Valentin; Dinescu, Maria

    2015-01-01

    Summary Laser pulse processing of surfaces and thin films is a useful tool for amorphous thin films crystallization, surface nanostructuring, phase transformation and modification of physical properties of thin films. Here we show the effects of nanostructuring produced at the surface and under the surface of amorphous GeTiO films through laser pulses using fluences of 10–30 mJ/cm2. The GeTiO films were obtained by RF magnetron sputtering with 50:50 initial atomic ratio of Ge:TiO2. Laser irradiation was performed by using the fourth harmonic (266 nm) of a Nd:YAG laser. The laser-induced nanostructuring results in two effects, the first one is the appearance of a wave-like topography at the film surface, with a periodicity of 200 nm and the second one is the structure modification of a layer under the film surface, at a depth that is related to the absorption length of the laser radiation. The periodicity of the wave-like relief is smaller than the laser wavelength. In the modified layer, the Ge atoms are segregated in spherical amorphous nanoparticles as a result of the fast diffusion of Ge atoms in the amorphous GeTiO matrix. The temperature estimation of the film surface during the laser pulses shows a maximum of about 500 °C, which is much lower than the melting temperature of the GeTiO matrix. GeO gas is formed at laser fluences higher than 20 mJ/cm2 and produces nanovoids in the laser-modified layer at the film surface. A glass transition at low temperatures could happen in the amorphous GeTiO film, which explains the formation of the wave-like topography. The very high Ge diffusivity during the laser pulse action, which is characteristic for liquids, cannot be reached in a viscous matrix. Our experiments show that the diffusivity of atomic and molecular species such as Ge and GeO is very much enhanced in the presence of the laser pulse field. Consequently, the fast diffusion drives the formation of amorphous Ge nanoparticles through the segregation of Ge

  10. Nanostructuring of GeTiO amorphous films by pulsed laser irradiation.

    PubMed

    Teodorescu, Valentin Serban; Ghica, Cornel; Maraloiu, Adrian Valentin; Vlaicu, Mihai; Kuncser, Andrei; Ciurea, Magdalena Lidia; Stavarache, Ionel; Lepadatu, Ana M; Scarisoreanu, Nicu Doinel; Andrei, Andreea; Ion, Valentin; Dinescu, Maria

    2015-01-01

    Laser pulse processing of surfaces and thin films is a useful tool for amorphous thin films crystallization, surface nanostructuring, phase transformation and modification of physical properties of thin films. Here we show the effects of nanostructuring produced at the surface and under the surface of amorphous GeTiO films through laser pulses using fluences of 10-30 mJ/cm(2). The GeTiO films were obtained by RF magnetron sputtering with 50:50 initial atomic ratio of Ge:TiO2. Laser irradiation was performed by using the fourth harmonic (266 nm) of a Nd:YAG laser. The laser-induced nanostructuring results in two effects, the first one is the appearance of a wave-like topography at the film surface, with a periodicity of 200 nm and the second one is the structure modification of a layer under the film surface, at a depth that is related to the absorption length of the laser radiation. The periodicity of the wave-like relief is smaller than the laser wavelength. In the modified layer, the Ge atoms are segregated in spherical amorphous nanoparticles as a result of the fast diffusion of Ge atoms in the amorphous GeTiO matrix. The temperature estimation of the film surface during the laser pulses shows a maximum of about 500 °C, which is much lower than the melting temperature of the GeTiO matrix. GeO gas is formed at laser fluences higher than 20 mJ/cm(2) and produces nanovoids in the laser-modified layer at the film surface. A glass transition at low temperatures could happen in the amorphous GeTiO film, which explains the formation of the wave-like topography. The very high Ge diffusivity during the laser pulse action, which is characteristic for liquids, cannot be reached in a viscous matrix. Our experiments show that the diffusivity of atomic and molecular species such as Ge and GeO is very much enhanced in the presence of the laser pulse field. Consequently, the fast diffusion drives the formation of amorphous Ge nanoparticles through the segregation of Ge atoms

  11. Corrosion Resistant Cladding by YAG Laser Welding in Underwater Environment

    SciTech Connect

    Tsutomi Kochi; Toshio Kojima; Suemi Hirata; Ichiro Morita; Katsura Ohwaki

    2002-07-01

    It is known that stress-corrosion cracking (SCC) will occur in nickel-base alloys used in Reactor Pressure Vessel (RPV) and Internals of nuclear power plants. A SCC sensitivity has been evaluated by IHI in each part of RPV and Internals. There are several water level instrumentation nozzles installed in domestic BWR RPV. In water level instrumentation nozzles, 182 type nickel-base alloys were used for the welding joint to RPV. It is estimated the SCC potential is high in this joint because of a higher residual stress than the yield strength (about 400 MPa). This report will describe a preventive maintenance method to these nozzles Heat Affected Zone (HAZ) and welds by a corrosion resistant cladding (CRC) by YAG Laser in underwater environment (without draining a reactor water). There are many kinds of countermeasures for SCC, for example, Induction Heating Stress Improvement (IHSI), Mechanical Stress Improvement Process (MSIP) and so on. A YAG laser CRC is one of them. In this technology a laser beam is used for heat source and irradiated through an optical fiber to a base metal and SCC resistant material is used for welding wires. After cladding the HAZ and welds are coated by the corrosion resistant materials so their surfaces are improved. A CRC by gas tungsten arc welding (GTAW) in an air environment had been developed and already applied to a couple of operating plants (16 Nozzles). This method was of course good but it spent much time to perform because of an installation of some water-proof working boxes to make a TIG-weldability environment. CRC by YAG laser welding in underwater environment has superior features comparing to this conventional TIG method as follows. At the viewpoint of underwater environment, (1) an outage term reduction (no drainage water). (2) a radioactive exposure dose reduction for personnel. At that of YAG laser welding, (1) A narrower HAZ. (2) A smaller distortion. (3) A few cladding layers. A YAG laser CRC test in underwater

  12. Effect of dental surface treatment with Nd:YAG and Er:YAG lasers on bond strength of resin composite to recently bleached enamel.

    PubMed

    Rocha Gomes Torres, Carlos; Caneppele, Taciana Marco Ferraz; Del Moral de Lazari, Regina; Ribeiro, Carolina Ferraz; Borges, Alessandra Buhler

    2012-07-01

    The aim of this work is to evaluate the effect of surface treatment with Er:YAG and Nd:YAG lasers on resin composite bond strength to recently bleached enamel. In this study, 120 bovine incisors were distributed into two groups: group C: without bleaching treatment; group B: bleached with 35% hydrogen peroxide. Each group was divided into three subgroups: subgroup N: without laser treatment; subgroup Nd: irradiation with Nd:YAG laser; subgroup Er: irradiation with Er:YAG laser. The adhesive system (Adper Single Bond 2) was then applied and composite buildups were constructed with Filtek Supreme composite. The teeth were sectioned to obtain enamel-resin sticks (1 × 1 mm) and submitted to microtensile bond testing. The data were statistically analyzed by the ANOVA and Tukey tests. The bond strength values in the bleached control group (5.57 MPa) presented a significant difference in comparison to the group bleached and irradiated with Er:YAG laser (13.18 MPa) or Nd:YAG (25.67 MPa). The non-bleached control group presented mean values of 30.92 MPa, with statistical difference of all the others groups. The use of Nd:YAG and Er:YAG lasers on bleached specimens was able to improve the bond strengths of them.

  13. High-peak power, passively Q-switched, composite, all-polycrystalline ceramic Nd:YAG/Cr{sup 4+}:YAG lasers

    SciTech Connect

    Sandu, O; Salamu, G; Pavel, N; Dascalu, T; Chuchumishev, D; Gaydardzhiev, A; Buchvarov, I

    2012-03-31

    High-peak power, passively Q-switched, composite Nd : YAG/Cr{sup 4+} : YAG lasers consisting of all-polycrystalline bonded Nd:YAG and Cr{sup 4+}:YAG ceramics are developed, and two applications of such lasers are discussed. A 1.1-at. %-doped Nd:YAG/Cr{sup 4+}:YAG ceramic laser is fabricated, which is quasi-cw pumped by a diode laser in the Hz-range, delivering laser pulses of 2.5-mJ energy and 1.9-MW peak power. By frequency doubling the laser output in a LiB{sub 3}O{sub 5} (LBO) nonlinear crystal at room temperature, 0.36-mJ, 0.3-MW green laser pulses with 27 % conversion efficiency are produced at 532 nm. Furthermore, a highly doped (1.5-at. %) Nd:YAG/Cr{sup 4+}:YAG ceramic laser operates successfully in the range of pulse repetition rates from 50 to 500 Hz, yielding 0.8-to-1.0 mJ pulses with a peak power around 1 MW. The laser output beam is amplified in a master-oscillator - power-amplifier (MOPA) system to generate laser pulses with 11-mJ energy at a 250-Hz repetition rate. (lasers)

  14. Locomotion of Amorphous Surface Robots

    NASA Technical Reports Server (NTRS)

    Bradley, Arthur T. (Inventor)

    2016-01-01

    An amorphous robot includes a compartmented bladder containing fluid, a valve assembly, and an outer layer encapsulating the bladder and valve assembly. The valve assembly draws fluid from a compartment(s) and discharges the drawn fluid into a designated compartment to displace the designated compartment with respect to the surface. Another embodiment includes elements each having a variable property, an outer layer that encapsulates the elements, and a control unit. The control unit energizes a designated element to change its variable property, thereby moving the designated element. The elements may be electromagnetic spheres with a variable polarity or shape memory polymers with changing shape and/or size. Yet another embodiment includes an elongated flexible tube filled with ferrofluid, a moveable electromagnet, an actuator, and a control unit. The control unit energizes the electromagnet and moves the electromagnet via the actuator to magnetize the ferrofluid and lengthen the flexible tube.

  15. Locomotion of Amorphous Surface Robots

    NASA Technical Reports Server (NTRS)

    Bradley, Arthur T. (Inventor)

    2014-01-01

    An amorphous robot includes a compartmented bladder containing fluid, a valve assembly, and an outer layer encapsulating the bladder and valve assembly. The valve assembly draws fluid from a compartment(s) and discharges the drawn fluid into a designated compartment to displace the designated compartment with respect to the surface. Another embodiment includes elements each having a variable property, an outer layer that encapsulates the elements, and a control unit. The control unit energizes a designated element to change its variable property, thereby moving the designated element. The elements may be electromagnetic spheres with a variable polarity or shape memory polymers with changing shape and/or size. Yet another embodiment includes an elongated flexible tube filled with ferrofluid, a moveable electromagnet, an actuator, and a control unit. The control unit energizes the electromagnet and moves the electromagnet via the actuator to magnetize the ferrofluid and lengthen the flexible tube.

  16. Biologically formed amorphous calcium carbonate.

    PubMed

    Weiner, Steve; Levi-Kalisman, Yael; Raz, Sefi; Addadi, Lia

    2003-01-01

    Many organisms from a wide variety of taxa produce amorphous calcium carbonate (ACC), despite the fact that it is inherently unstable and relatively soluble in its pure state. These properties also make it difficult to detect and characterize ACC. Raman spectroscopy is a particularly useful method for investigating ACC because the sample can be examined wet, and extended X-ray absorption fine structure (EXAFS) analysis can provide detailed information on the short-range order. Other methods for characterizing ACC include infrared spectroscopy, thermogravimetric analysis and differential thermal analysis (TGA and DTA), transmission electron microscopy (TEM), and electron and X-ray diffraction. Because of the difficulties involved, we suspect that ACC is far more widely distributed than is presently known, and a comparison of EXAFS spectra shows that different biogenic ACC phases have different short-range order structures. We also suspect that ACC fulfils many different functions, including as a transient precursor phase during the formation of crystalline calcium carbonate.

  17. Bonding Strength of Ceromer with Direct Laser Sintered, Ni-Cr-Based, and ZrO2 Metal Infrastructures After Er:YAG, Nd:YAG, and Ho:YAG Laser Surface Treatments-A Comparative In Vitro Study.

    PubMed

    Gorler, Oguzhan; Ozdemir, Ali Kemal

    2016-08-01

    Laser modalities instead of conventional surface treatment techniques have been suggested to obtain an adequate micromechanical bonding between dental super- and infrastructures. The present study was undertaken to assess the effect of surface treatment with Ho:YAG, Er:YAG, and Nd:YAG laser modalities on the shear bond strength (SBS) of ceromer to different types of metal infrastructures in in vitro settings. The study specimens consisted of 40 direct laser sintered (DLS), 40 Ni-Cr-based, and 40 zirconium oxide (ZrO2) infrastructures. In each infrastructure group, the specimens were divided randomly into five treatment modalities (n = 8): no treatment (controls), sandblasting, Er:YAG, Nd:YAG, and Ho:YAG lasers. The DLS, Ni-Cr-based, and ZrO2 infrastructures were prepared in the final dimensions of 7 mm in diameter and 3 mm in thickness in line with the ISO 11405 standard. Ceromer as superstructure was applied to all the infrastructures after their surface treatments according to the selected treatment modality. SBS test was performed to test the effectiveness of surface treatments. A stereomicroscope was used to determine the changes in the surface morphology of specimens. Among the laser modalities and sandblasting, Ho:YAG laser caused the most important increase in the DLS and Ni-Cr-based infrastructures but sandblasting caused the most important increase in the ZrO2 infrastructure. In all the infrastructures, Nd:YAG laser has the least effectiveness, and Er:YAG laser makes an intermediate success. The stereomicroscopy images presented that the applications of laser surface treatments altered the surface in all the infrastructures. Overall, in current experimental settings, Ho:YAG, Nd:YAG, and Er:YAG lasers, in order of strength, are effective in improving the bonding of ceromer to all the infrastructures. Ho:YAG laser is more effective in the DLS and Ni-Cr-based infrastructures, but sandblasting is more effective in the ZrO2 infrastructure. The studied

  18. Amplification of complex fields in Nd:YAG amplifiers

    NASA Astrophysics Data System (ADS)

    Chen, Xudong; Chang, Chengcheng; Pu, Jixiong

    2017-04-01

    High energy nanosecond vortex beams and cylindrically polarized beams are generated in Nd:YAG amplifiers. Vortex seed beams and cylindrically polarized seed beams are converted from a conventional Nd:YAG laser by spiral phase plate and polarization converter, respectively. Maximum output energy of optical vortex up to 995 mJ and cylindrically polarized beams up to 772 mJ have been achieved at 10 Hz in a 10-ns pulse, respectively. The amplification efficiency, the beam quality and pulse width of the amplification output are studied. Both the topological charge of the vortex seed beams and polarization state of cylindrically polarized beams are confirmed to be conserved during the amplification. The generation of high energy vortex beams and cylindrically polarized beams would be beneficial to laser material processing.

  19. Endobronchial occlusive disease: Nd:YAG or PDT?

    NASA Astrophysics Data System (ADS)

    Regal, Anne-Marie; Takita, Hiroshi

    1991-06-01

    Patients with endobronchial occlusion commonly experience dyspnea, cough, hemoptysis, pneumonitis, and atelectasis. If luminal patency is not re-established, obstructive symptoms may progress to sepsis and death. Although the overall survival of patients with lung cancer may not be altered by relief of airway obstruction, the prognosis for this subset of patients may be improved by eliminating the septic complications of bronchial occlusion. Techniques to treat occluded bronchi include electro-fulguration, cryotherapy, brachytherapy, laser (CO2, Nd-YAG) therapy, and photodynamic therapy (PDT). These represent local forms of treatment and are intended to be palliative. Nd-YAG and PDT are the modalities more frequently utilized in this setting. Comparison of the two treatment forms may furnish insight regarding the appropriate role for each as individual therapies and as part of the armamentarium of cancer therapies.

  20. Er:YAG and adhesion in conservative dentistry : clinical overview

    PubMed Central

    Fornaini, Carlo

    2013-01-01

    The notion of utilizing laser technology in conservative dentistry was proposed in 1990 by Hibst and Keller, who introduced the possibility of using an Er:YAG laser as alternative to conventional instruments such as the turbine and micro-motor. In subsequent years a continuing effort has been made by clinicians, researchers and commercial companies to improve the technology. The aim of this clinical study is to demonstrate, by the description of different clinical cases, the possibilities and the advantages of using Er:YAG lasers in conservative dentistry and to show that better results may be achieved in terms of stronger adhesion, less invasiveness, reduced pain as well as greater comfort and satisfaction of patients. PMID:24155547

  1. Nd:YAG development for spaceborne laser ranging system

    NASA Technical Reports Server (NTRS)

    Harper, L. L.; Logan, K. E.; Williams, R. H.; Stevens, D. A.

    1979-01-01

    The results of the development of a unique modelocked laser device to be utilized in future NASA space-based, ultraprecision laser ranger systems are summarized. The engineering breadboard constructed proved the feasibility of the pump-pulsed, actively modelocked, PTM Q-switched Nd:YAG laser concept for the generation of subnanosecond pulses suitable for ultra-precision ranging. The laser breadboard also included a double-pass Nd:YAG amplifier and provision for a Type II KD*P frequency doubler. The specific technical accomplishment was the generation of single 150 psec, 20-mJ pulses at 10 pps at a wavelength of 1.064 micrometers with 25 dB suppression of pre-and post-pulses.

  2. Pulsed Tm:YAG laser ablation of knee joint tissues

    NASA Astrophysics Data System (ADS)

    Shi, Wei-Qiang; Vari, Sandor G.; Duffy, J. T.; Miller, J. M.; Weiss, Andrew B.; Fishbein, Michael C.; Grundfest, Warren S.

    1992-06-01

    We investigated the effect of a free-running 2.01 micron pulsed Tm:YAG laser on bovine knee joint tissues. Ablation rates of fresh fibrocartilage, hyaline cartilage, and bone were measured in saline as a function of laser fluence (160 - 640 J/cm2) and fiber core size (400 and 600 microns). All tissues could be effectively ablated and the ablation rate increased linearly with the increasing fluence. Use of fibers of different core sizes, while maintaining constant energy fluence, did not result in significant difference in ablation rate. Histology analyses of the ablated tissue samples reveal average Tm:YAG radiation induced thermal damage (denatunalization) zones ranging between 130 and 540 microns, depending on the laser parameters and the tissue type.

  3. Effects of Er:YAG laser irradiation on human cartilage

    NASA Astrophysics Data System (ADS)

    Glinkowski, Wojciech; Brzozowska, Malgorzata; Ciszek, Bogdan; Rowinski, Jan; Strek, Wieslaw

    1996-03-01

    Irradiation of the hyaline or fibrous cartilage excised from the body of a human cadaver with Er:YAG laser beam, single pulse with a dose of 1 J, produces a crater with a depth of approximately 500 micrometers and a diameter varying from 5 to 300 micrometers. Histological examination has revealed that the laser-made craters were surrounded by a thin rim (2-10 micrometer) of charred and coagulated tissue. No damage was observed in the cartilage surrounding the rim. The presence of sharp demarcation between the tissue areas ablated by laser energy and the undamaged areas argues for the potential usefulness of the Er:YAG laser in surgery of cartilages.

  4. Nd:YAG laser cutting of advanced ceramics

    NASA Astrophysics Data System (ADS)

    Quintero, F.; Pou, Juan; Lusquinos, F.; Boutinguiza, M.; Soto, R.; Perez-Amor, Mariano

    2001-08-01

    The manufacturing of elements made of advance ceramics is done traditionally by the use of diamond coated tools. The inherent properties of those materials such as very high hardness and brittleness, made machining a very hard work; being noisy, powdery and unsafe for the worker. Thus, there is a need to introduce new processing methods in order to improve the working conditions and also the quality of the products. In this paper we present the result of the work carried out to investigate the possibilities of an optical fiber guided Nd:YAG laser to cut mullite-alumina plates. We used a 500 W pulsed Nd:YAG laser to perform different experiments in which the influence of the average laser power and the assist gas pressure on the maximum cutting speed was studied.

  5. High efficiency Yb:YAG crystalline fiber-waveguide lasers.

    PubMed

    Mu, Xiaodong; Meissner, Stephanie; Meissner, Helmuth; Yu, Anthony W

    2014-11-01

    A laser diode (LD) cladding pumped single-mode 1030 nm laser has been demonstrated, in an adhesive-free bonded 40 μm core Yb:YAG crystalline fiber waveguide (CFW). A laser output power of 13.2 W at a wavelength of 1.03 μm has been achieved, for an input pump power of 39.5 W. The corresponded laser efficiency is 33.4%. The laser beam quality is confirmed to be near diffraction-limited, with a measured M2 = 1.02. A LD core pumped single-clad Yb:YAG CFW laser has also been demonstrated with a top-hat laser beam profile, with a laser output power of 28 W and a slope efficiency of 78%.

  6. Tunable eye-safe Er:YAG laser

    NASA Astrophysics Data System (ADS)

    Němec, M.; Šulc, J.; Indra, L.; Fibrich, M.; Jelínková, H.

    2015-01-01

    Er:YAG crystal was investigated as the gain medium in a diode (1452 nm) pumped tunable laser. The tunability was reached in an eye-safe region by an intracavity birefringent filter. The four tuning bands were obtained peaking at wavelengths 1616, 1632, 1645, and 1656 nm. The broadest continuous tunability was 6 nm wide peaking at 1616 nm. The laser was operating in a pulsed regime (10 ms pulse length, 10 Hz repetition rate). The maximum mean output power was 26.5 mW at 1645 nm. The constructed system demonstrated the tunability of a resonantly diode-pumped Er:YAG laser which could be useful in the development of compact diode-pumped lasers for spectroscopic applications.

  7. Optical characterizations on surface-polished polycrystalline YAG fibers

    NASA Astrophysics Data System (ADS)

    Kim, Hyunjun; Hay, Randall S.; McDaniel, Sean A.; Cook, Gary; Usechak, Nicholas G.; Urbas, Augustine M.; Lee, HeeDong; Corns, Randall G.; Shugart, Kathleen N.; Kadhim, Ali H.; Brown, Dean P.; Griffin, Benjamin

    2017-05-01

    The superior thermal and optical properties of transparent polycrystalline ceramics make them attractive alternatives to glass-based materials for laser gain media. Fibers have other advantages of compactness, vibration-resistance, and reduced cooling requirements. Recently it was found that surface roughness caused by grain boundary grooving dominated optical scattering even though there were other scattering sources in the fiber. Therefore, a lot of effort went to fabrication of fibers with smooth surfaces. A mechanical polishing method for polycrystalline YAG fibers was developed. The fiber surface roughness was reduced, while maintaining a circular cross-section. Surface-polished 1.5% Ho-doped polycrystalline YAG fiber, 62 mm long with 31 μm diameter, was fabricated, and lasing was demonstrated from this fiber. Effects of surface-polishing on the surface roughness and scattering coefficient are presented, and lasing characteristics are discussed.

  8. NdYAG laser photocoagulation in the dog stomach.

    PubMed Central

    Bown, S G; Salmon, P R; Storey, D W; Calder, B M; Kelly, D F; Adams, N; Pearson, H; Weaver, B M

    1980-01-01

    Considerable discussion still centres around the relative merits of the Argon and Neodymium Yttrium Aluminum Garnet (NdYAG) lasers for the endoscopic treatment of gastrointestinal haemorrhage, although both are undoubtedly effect. We have carried out experiments to elucidate which factors determine the safety and efficacy of NdYAG laser photocoagulation. Histological studies on normal gastric mucosa showed that the depth of tissue damage depended mainly on the total incident laser energy, whereas the effectiveness of photocoagulation of induced gastric ulcers in heparinised animals depended on the laser power and the exposure time used. Optimum haemostasis with minimum tissue damage was obtained using pulses of 300 to 500 ms duration with energies of 25 to 40 J. We consider these parameters safe and effective for use in pilot clinical studies. PMID:7192243

  9. Modeling a diode pumped Nd: YAG rod laser

    NASA Astrophysics Data System (ADS)

    Shu, Hong; Chen, Ying; Bass, Michael; Acharekar, Madhu A.

    2006-02-01

    We evaluate the performance potential of a diode pumped Nd: YAG rod laser by finding the absorbed pump distribution using ASAP, pump induced thermal lensing, gain medium surface distortion and stresses using FEMLAB and depolarization losses using MATLAB. Beam propagation in the optically distorted Nd:YAG rod and the free space part of the cavity, and the output laser beam were determined with a computational scheme we developed which employs the beam propagation method combined with sparse matrix technology. We propose a special cavity design that can select the spatial eigen mode shape of the laser and simultaneously compensate for pump induced thermal lensing, gain medium surface distortion and birefringence. The converged solutions calculated this special cavity design give both high extraction efficiency and good output beam quality. Sensitivity of the output beam to mirror tilt, thermal induced mirror distortion, and errors in the cavity length or the optical distortions in the rod were also calculated.

  10. Holmium:YAG laser discectomy in dogs: a pilot project

    NASA Astrophysics Data System (ADS)

    Fry, Thomas R.; Bartels, Kenneth E.; Henry, George A.; Schafer, Steven A.; Stair, Ernest L.; Nordquist, Robert E.; Powell, Richard C.

    1994-09-01

    Objectives of our project were to determine the affects of Ho:YAG laser energy on canine intervertebral (IV) discs by thermography, and histology. Multiple IV discs in three cadaveric nonchondrodystrophoid spines were treated with 20 J to 180 J of energy and evaluated by thermography and histology. Histologic evaluation revealed thermal affects at all doses including potential acoustic wave affects, increased eosinophilia, carbonization, and in some cases a large defect due to laser irradiation. Laser affects were confined only to the nucleus pulposus and annulus fibrosus with adjacent structures unaffected. In an acute study, two nonchondrodystrophoid dogs were sacrificed after IV discs were treated with 20 - 180 J of Ho:YAG laser radiation, following an extensive dorsal laminectomy to allow placement of thermoprobes in spinal and spinal cord structures. Heating occurred in only the nucleus pulposus and annulus fibrosus with minimal temperature changes in the adjacent structures including the spinal cord.

  11. Crystalline to amorphous transformation in silicon

    SciTech Connect

    Cheruvu, S.M.

    1982-09-01

    In the present investigation, an attempt was made to understand the fundamental mechanism of crystalline-to-amorphous transformation in arsenic implanted silicon using high resolution electron microscopy. A comparison of the gradual disappearance of simulated lattice fringes with increasing Frenkel pair concentration with the experimental observation of sharp interfaces between crystalline and amorphous regions was carried out leading to the conclusion that when the defect concentration reaches a critical value, the crystal does relax to an amorphous state. Optical diffraction experiments using atomic models also supported this hypothesis. Both crystalline and amorphous zones were found to co-exist with sharp interfaces at the atomic level. Growth of the amorphous fraction depends on the temperature, dose rate and the mass of the implanted ion. Preliminary results of high energy electron irradiation experiments at 1.2 MeV also suggested that clustering of point defects occurs near room temperature. An observation in a high resolution image of a small amorphous zone centered at the core of a dislocation is presented as evidence that the nucleation of an amorphous phase is heterogeneous in nature involving clustering or segregation of point defects near existing defects.

  12. Investigation of bulk laser damage in transparent YAG ceramics controlled with microstructural refinement

    NASA Astrophysics Data System (ADS)

    Kamimura, T.; Kawaguchi, Y.; Arii, T.; Shirai, W.; Mikami, T.; Okamoto, T.; Aung, Yan Lin; Ikesue, A.

    2008-10-01

    We have investigated a relationship among the bulk laser-induced damage threshold (LIDT) and YAG ceramics with various structural defects. The correlation of scattering defect density and laser damage resistance was clearly observed. A high-quality YAG ceramic having a low-scattering density showed a higher LIDT than that of a low-quality YAG ceramic. Laser damage threshold (LIDT) of high-quality YAG ceramic was almost the same as that of a single crystal. In addition, the high-quality Nd:YAG ceramics with low-defect density showed an excellent oscillation efficiency which was comparable to that of a single crystal. Thus, high-quality YAG ceramic with low-defect density is more reliable as a material which is highly resistant to laser damage.

  13. 165-W cryogenically cooled Yb:YAG laser.

    PubMed

    Ripin, Daniel J; Ochoa, Juan R; Aggarwal, R L; Fan, Tso Yee

    2004-09-15

    Thermo-optic distortions often limit the beam quality and power scaling of high-average-power lasers. Cryogenically cooled Yb:YAG is used to efficiently generate 165 W of near-diffraction-limited beam from a power oscillator with negligible thermo-optic effects. End pumped with 215 W of incident pump power from two diode modules, the laser has an optical-optical efficiency of 76%, a slope efficiency of 85%, and an M2 value of 1.02.

  14. Neodymium YAG Lasers. Citations from the NTIS data base

    NASA Astrophysics Data System (ADS)

    Carrigan, B.

    1980-07-01

    Federally funded research reports on lasing of neodymium doped yttrium aluminum garnet are cited. Studies on design, fabrication, quantum efficiency, light pulses, stabilization, and testing are covered. Optical pumping, mode locking, frequency conversion, and modulation of these lasers are discussed. Laser applications such as optical communication, range finding, and tracking are included. Safety hazards and radiation damage related to neodymium YAG lasers are also covered. This updated bibliography contains 181 citations, 15 of which are new entries to the previous edition.

  15. Continuous two-wave lasing in microchip Nd : YAG lasers

    SciTech Connect

    Ievlev, Ivan V; Koryukin, Igor' V; Lebedeva, Yu S; Khandokhin, Pavel A

    2011-08-31

    Simultaneous two-wave lasing was obtained in microchip end-pumped Nd:YAG lasers at the wavelengths of 1061.5 and 1064.17 nm at room temperature. Laser wave intensities were studied as functions of crystal temperature and pump power. The ranges of parameters were determined in which the two-wave lasing occurs and the reasons for such lasing were established. A model is suggested, which adequately describes the experimental results obtained. (control of radiation parameters)

  16. Superficial erbium:YAG laser resurfacing of photodamaged skin.

    PubMed

    Pozner, Jason N; Goldberg, David J

    2006-06-01

    Light chemical peels and microdermabrasion have enjoyed recent popularity for the treatment of mild photoaging. However, clinical improvement from these modalities is often minimal from both a patient's and physician's perspective. Erbium:YAG lasers have been effective in treating mild to moderate photoaging, but the need for either regional or general anesthesia, as well as the significant post-treatment recovery period has limited its use. We sought to utilize a very low fluence approach to erbium:YAG laser resurfacing, with topical anesthesia, to ascertain its efficacy in treating mild to moderate photoaging. A total of 250 subjects aged 28-80 years with skin types 1-4 and mild to moderate facial rhytids were treated with topical anesthesia and subsequently one pass of a 2940 nm erbium:YAG laser, using between 5 and 17.5 J/cm2. In addition, 58 of the treated facial subjects underwent neck resurfacing with fluences between 5 and 15 J/cm2 and eight treated facial subjects underwent upper chest resurfacing at fluences of 5-7 J/cm2. A single treatment was received by 246 subjects; four subjects were treated a second time after a 1-month interval. Most subjects completely re-epithelialized by 3-4 days; healing time was depth dependent. Most subjects were able to start skin care regimens within 1-2 weeks after the procedure. Results were judged to be excellent in individuals with thin skin and good in subjects with thicker skin. One pass of low fluence erbium:YAG resurfacing, under topical anesthesia, was effective for the treatment of mild to moderate photoaging.

  17. Tracheal papillomatosis treated with Nd-Yag laser resection.

    PubMed

    Hunt, J M; Pierce, R J

    1988-10-01

    We report a case of tracheal papillomatosis in a 69-year-old woman who presented with stridor and functional evidence of large airway obstruction. She was successfully treated by endobronchial resection using a Neodymium Yag laser. This provided lasting symptomatic relief of dyspnea. Respiratory papillomatosis is a disease predominantly of the childhood larynx and its presentation with predominant tracheal involvement late in life is extremely uncommon. Laser therapy provides an extremely effective treatment modality for this condition.

  18. Nd:Yag goniopuncture after deep sclerectomy with collagen implant.

    PubMed

    Mermoud, A; Karlen, M E; Schnyder, C C; Sickenberg, M; Chiou, A G; Hédiguer, S E; Sanchez, E

    1999-02-01

    To study the need, the safety and the success rate of Nd:Yag goniopuncture in eyes that underwent deep sclerectomy with collagen implant. The first 100 patients that underwent deep sclerectomy with collagen implant were prospectively followed. Deep sclerectomy with collagen implant is a non-penetrating filtering surgery which allows filtration of aqueous from the anterior chamber to the subconjunctival space through a remaining trabeculo-Descemet's membrane without opening the anterior chamber. Goniopunctures with Nd:Yag laser were performed at the site of surgery when the filtration through the trabeculo-Descemet's membrane was considered to be insufficient with elevated intraocular pressure. The laser treatment was performed using a Lasag 15 gonioscopy contact lens (CGA1). Goniopunctures were performed using the free-running Q-switched mode with an energy ranging from 2 to 4 mJ. Of 100 patients who underwent deep sclerectomy with collagen implant, goniopunctures with Nd:Yag laser were performed in 41 patients (41%). The mean time between deep sclerectomy with collagen implant and goniopuncture was 9.9 months +/-1.2 months (+/-SE). The mean IOP before laser treatment was 22.2 mm +/-7.0 mm Hg and decreased to 12.5 mm +/-5.8 mm Hg immediately after laser treatment and remained stable for the next 2 years of follow-up. The immediate success rate of goniopuncture was 83%. Choroidal detachment occurred in two patients (5%). Nd:Yag goniopuncture is an efficient and safe treatment for low filtration through the trabeculo-Descemet's membrane after deep sclerectomy with collagen implant.

  19. Changes in intrapulpal temperature after Er:YAG laser irradiation.

    PubMed

    Park, N S; Kim, K S; Kim, M E; Kim, Y S; Ahn, S W

    2007-06-01

    This study was performed to investigate the changes in temperature induced by an Er:YAG laser irradiation and to find the means to minimize potential thermal damage due to temperature rise after irradiation. Intrapulpal temperature rise was found to last after irradiation at times, although the addition of appropriate water spray during tooth ablation by Er:YAG laser produced efficient ablation with little thermal damage. To investigate intrapulpal temperature change, each extracted tooth specimen was embedded into a resin block and temperature-measuring probes were placed on the irradiated and the opposite pulpal walls. An Er:YAG laser irradiation was performed at 300 mJ/pulse and 20 Hz, with a water flow rate of 1.6 mL/min for 3 sec. Each lasing was followed by (1) no application of post-irradiation water spray, (2) post-irradiation water spray for 1 sec and (3) for 2 sec. No significant temperature change was found on the irradiated pulpal wall during Er:YAG laser, while there existed significant temperature rise on the irradiated pulpal wall after irradiation. However, the addition of water spray for 1 or 2 sec after irradiation significantly decreased intrapulpal temperature compared to no application of post-irradiation water spray. There were no significant differences between the 1- and 2-sec groups. It is suggested that the addition of water spray for 1 or more seconds after irradiation reduces post-irradiation temperature rise, possibly leading to thermal damage on the dental pulp tissue.

  20. Smart Ho:YAG laser lithotriptor using optical correlation

    NASA Astrophysics Data System (ADS)

    Kokaj, Jahja O.; Marafi, Mustafa A.; Makdisi, Yacob; Bhatia, Kuldip S.; Mathew, K. J.; Caka, Nebi; Hasani, Rexhep

    1998-03-01

    Ultra fast imaging and destruction of the gall bladder stone is performed using Ho:YAG laser. A laser guided approach for lithotropsy is proposed. The correlation output peak is introduced as a feedback signal for firing the laser pulse for stone destruction and 'discrimination' of the tissue image so that the risk of damaging and perforation of the tissue is reduced. A system constituted by correlation of ballistic images and fluorescent signals is proposed.

  1. The Effects of Er:YAG, Nd:YAG, and Ho:YAG Laser Surface Treatments to Acrylic Resin Denture Bases on the Tensile Bond Strength of Silicone-Based Resilient Liners.

    PubMed

    Gorler, Oguzhan; Dogan, Derya Ozdemir; Ulgey, Melih; Goze, Aysegul; Hubbezoğlu, Ihsan; Zan, Recai; Ozdemir, Ali Kemal

    2015-08-01

    The present study was to assess the effect of surface treatments of Er:YAG, Nd:YAG, and Ho:YAG lasers on the tensile bond strength of a silicone-based resilient liner to an acrylic denture in an in vitro setting. Experimental dumbbell-shaped specimens (75 mm) were produced by combining two acrylate pieces fabricated from heat-polymerized acrylic resin (36 mm) with 3 mm of Molloplast(®)-B filling between them. The specimens (n=200) were randomly divided in half for thermocycling, and each 100 specimen set was randomized into five groups (n=20) with different surface treatments: control (no surface treatment), sandblasting, Er:YAG laser, Nd:YAG laser, and Ho:YAG laser. A tensile bond strength test was performed. The effect of the laser surface treatments was examined with scanning electron microscopy. Only the Er:YAG laser increased the tensile bond strength compared with the other treatments. The other laser groups showed lower bond strengths. The Ho:YAG laser resulted in considerably reduced tensile bond strength. The scanning electron microscopy images showed that applying laser surface treatments modified the surface of the denture base resin. There was not an overall improvement with the use of the studied laser modalities in the adhesion quality of resilient denture liner to acrylic resin, although Er:YAG laser showed a potential to improve their adhesion. These laser modalities need to be subjected to further studies to determine optimal setup for use in prosthodontics.

  2. Effect of pulsed Nd:YAG on dentin morphological changes

    NASA Astrophysics Data System (ADS)

    Moriyama, Eduardo H.; Zangaro, Renato A.; Villaverde, Antonio G. J. B.; Watanabe-Sei, Ii; Munin, Egberto; Sasaki, Luis H.; Otsuka, Daniel K.; Lobo, Paulo D. d. C.; Pacheco, Marcos T. T.; Junior, Durval R.

    2002-06-01

    Infrared lasers have been used for several clinical applications in dentistry, including laser ablation, oral surgeries and dentin hypersensitivity treatment. Despite of dentin low absorption coefficient in the near infrared spectrum, Nd:YAG laser radiation ((lambda) = 1064 nm) is able to melt the human dentin surface resulting in dentin tubules closure that can suppress the symptoms of dentin hypersensitivity pathology. Objectives: This study aims to analyze, through SEM technique, the morphological changes in dentin surface after Nd:YAG laser irradiation using different parameters in energy distribution. Materials and Methods: In this study sixteen human dentin samples were submitted to Nd:YAG laser radiation using a total energy of 900mJ distributed in one, two, three or six laser pulses with energy for each pulse of 900, 450, 300 or 150 mJ respectively. All the samples were irradiated with laser pulse width of 90ms, pulse intervals of 300 ms and spot size area of 0,005 cm2. Results: SEM analysis suggests that differences in energy distribution results in morphological differences even though the same energy is used for all the samples.

  3. Temperature variation during apicectomy with Er:YAG laser.

    PubMed

    Bodrumlu, Emre; Keskiner, Ilker; Sumer, Mahmut; Sumer, A Pinar; Telcıoglu, N Tuba

    2012-08-01

    The purpose of this in vitro study was to evaluate the generated temperature of the Er:YAG laser, with three different pulse durations for apicectomy, compared with tungsten bur and surgical saw. Apicectomy is an endodontic surgery performed to remove the root apex and curette adjacent periapical tissue because of lesions of the apical area that are not healing properly. Sixty single-rooted extracted human teeth were resected by three cutting methods: tungsten bur, surgical saw, and Er:YAG laser irradiation with three different pulse durations; pulse duration 50 μs, pulse duration 100 μs, and pulse duration 300 μs. Teflon-insulated, type K thermocouples were used to measure temperature changes during the apicectomy process. Data were analyzed using the general linear models procedure of the SPSS statistical software program. Although there was no statistically significant difference for the mean values of temperature changes at 1 mm away to the cutting site of teeth, there was statistically significant difference among groups for the mean values of temperature changes at 3 mm away to the cutting site of teeth. Additionally, there was statistically significant difference among groups for the total time required for apicectomy. The laser irradiation with pulse duration 50 μs appears to have the lowest temperature rise and the shortest time required for apicectomy of the three pulse durations. However, Er:YAG laser for apicectomy in all pulse durations could be used safely for resection in endodontics in the presence of sufficient water.

  4. Microwave sintering of Yb:YAG transparent laser ceramics

    NASA Astrophysics Data System (ADS)

    Esposito, Laura; Piancastelli, Andreana; Bykov, Yury; Egorov, Sergei; Eremeev, Anatolii

    2013-02-01

    Reactive sintering of YAG based ceramics is generally performed under high vacuum in graphite-free furnaces in order to guarantee the elimination of pores and absence of any contamination. An alternative densification technique is the field assisted process such as spark plasma sintering and microwave sintering. Both of these methods are characterized by very fast heating rates, low sintering temperatures and short sintering times. The microwave sintering process is different from electric resistance heating since heat is generated in the bulk of the powder compact through electromagnetic radiation absorption and creates within its body uniform temperature distribution. Microwave sintering of laser ceramics is advantageously distinguished by the absence of any elements having high temperature such as electric heaters or dies which materials can contaminate the sintered parts. In addition, the inverse temperature distribution that exists within the body under volumetric microwave heating is favorable for elimination of porosity. Microwave sintering of Yb:YAG samples were tested and the obtained results are presented. The samples were sintered on a gyrotron-based system operating at a frequency of 24 GHz with microwave power up to 6 kW. Reactive sintering of YAG doped with 1.0, 5.0, and 9.8 at.% Yb2O3 was performed in different temperature-time regimes. The microstructure and the optical transmittance of the obtained samples were compared to those of samples obtained by conventional high vacuum sintering.

  5. Er:YAG clinical results on hard tissue: phase I

    NASA Astrophysics Data System (ADS)

    Cozean, Colette D.; Powell, G. L.

    1998-04-01

    Objective: This study was performed in order to establish that the pulpal and dentinal tissue are safe when exposed to the 2.94 micron pulsed Er:YAG laser radiation for the procedures of caries removal, cavity preparation, and etching prior to acid etching. This presentation discusses the histological results of a double-blind study comparing a pulsed Er:YAG with a standard dental drill. Methods: A double-blind histological evaluation of the pulpal and dentinal tissue changes induced by the Erbium laser and the dental drill was conducted on teeth extracted immediately following the dental procedure and at various intervals up to 1 year post-treatment. A statistical analysis was used to determine if any statistically significant clinical differences in dental tissue response could be observed between the Er:YAG laser and the standard dental drill. Conclusions: Analysis of the results indicated there were no significant differences observed between the laser and control groups in this study.

  6. Composite Yb:YAG/SiC-prism thin disk laser.

    PubMed

    Newburgh, G A; Michael, A; Dubinskii, M

    2010-08-02

    We report the first demonstration of a Yb:YAG thin disk laser wherein the gain medium is intracavity face-cooled through bonding to an optical quality SiC prism. Due to the particular design of the composite bonded Yb:YAG/SiC-prism gain element, the laser beam impinges on all refractive index interfaces inside the laser cavity at Brewster's angles. The laser beam undergoes total internal reflection (TIR) at the bottom of the Yb(10%):YAG thin disk layer in a V-bounce cavity configuration. Through the use of TIR and Brewster's angles, no optical coatings, either anti-reflective (AR) or highly reflective (HR), are required inside the laser cavity. In this first demonstration, the 936.5-nm diode pumped laser performed with approximately 38% slope efficiency at 12 W of quasi-CW (Q-CW) output power at 1030 nm with a beam quality measured at M(2) = 1.5. This demonstration opens up a viable path toward novel thin disk laser designs with efficient double-sided room-temperature heatsinking via materials with the thermal conductivity of copper on both sides of the disk.

  7. Bactericidal effect of Nd:YAG laser irradiation in endodontics

    NASA Astrophysics Data System (ADS)

    Aun, Carlos E.; Barberini, Alexandre F.; Camargo, Selma C. C.; Silva Kfouri, Luciana; Lorenzetti Simionato, Maria R.

    1999-05-01

    The success of endodontic therapy is based on the elimination of bacterial colonization from the endodontic system and periapical tissues. Recent studies have been showing the bactericidal effect of laser in root canal treatment. The propose of the study is to evaluate the effect of Nd:YAG laser irradiation in contaminated root canal treatment. The propose of the study is to evaluate the effect of Nd:YAG laser irradiation in contaminated root canals from upper central incisor. For the experiment 12 teeth were selected, respect at the apical third, sterilized, and 10 μm Streptococcus sanguis liquid culture were inoculated in the root canals. The laser test groups were irradiated with Nd:YAG laser at standard setting of 15Hz, 100mj and 1,5 W for 10, 20 and 30 seconds each in slow helicoidal movements from the apex to the top using a 300 micrometers fiber. After the procedure the specimens were placed in Tryptic Soy Agar, the number of colony forming units was evaluated. The experiment showed a significant reduction on viability of Streptococcus sanguis at the respective time of 20 and 30 seconds.

  8. Treatment of condylomata acuminata with Ho:YAG laser

    NASA Astrophysics Data System (ADS)

    Shi, Hongmin; Zhu, Jing; Zhang, Mei-Jue

    2005-07-01

    Objective: The purpose of this study to evaluate the effectiveness of Ho: YAG laser irradiation in treatment of condylomata acuminata. Methods: 1025 patients of condylomata acuminata, in which the lesions of 620 patients were interior of different lacuna, the lesions in 79 patients were huge (the diameter of lesion is over than 5cm), and 26 patients were pregnant, were treated with Ho:YAG laser (0.5-0.8J/pulse, 5-15 pulses/sec) to melt all the lesions. Results: All lesions in 1025 patients were removed after one laser treatment. The recrudescent and regenerative lesions could be removed completely after repeated treatment. No scarring and stricture on the peristome of the urethra was observed. No abortion, premature delivery and other syndrome were occurred among the total 26 pregnant patients. Conclusion: The technique of treatment of condylomata acuminata with Ho:YAG laser is an effective and safe therapeutics with the characteristic of better function of the homeostasis, shorter period of the concrescence and easy to operate.

  9. Efficiency issues in Ce{sup 3+} doped YAG nanocrystals

    SciTech Connect

    Vorsthove, Mark

    2011-11-15

    Graphical abstract: The organic coating inevitably obtained from glycothermal syntheses of nano YAG:Ce in 1,4-butanediol proved to be beneficial and disadvantageous at the same time. The overall efficiency of the materials is further limited due to a strong decrease of the absorbtion. Highlights: {yields} Evaluation of hydrothermal nano-YAG:Ce synthesis. {yields} Determination of concentration and particle size dependence of optical properties. {yields} Analysis of surface species. {yields} Identification of efficiency limitations and bottlenecks. -- Abstract: Nanoparticles of Y{sub 3}Al{sub 5}O{sub 12}:Ce{sup 3+} (YAG:Ce{sup 3+}, 1%) were synthesized via the glycothermal method. The particle sizes were estimated by transmission electron microscopy, X-ray diffraction, surface area determination and by dynamic light scattering. We found primary particles of 10-14 nm in diameter, which form agglomerates of approximately 100 nm. For the 4f {yields} 5d transition of Ce{sup 3+} an internal quantum efficacy of up to 46% was measured. The particles consist of 6-10% of 1,4-butanediol attached on the surface, as determined by carbon content measurements in combination with IR and absorption spectroscopy. In particular, limiting drawbacks due to inevitable surface coatings for glycothermal syntheses and nanoscale associated scattering are elucidated.

  10. Accidental macular hole following neodymium:YAG posterior capsulotomy.

    PubMed

    Munteanu, Mihnea; Petrović, Zarko; Stanca, Horia; Rosca, Cosmin; Jianu, Adelina; Boruga, Ovidiu

    2014-01-01

    Posterior capsular opacification (PCO) is the commonest complication of cataract surgery, occurring in up to one-third of patients in a period of five years. The treatment of choice is the Neodymium:YAG laser posterior capsulotomy. This treatment can be associated with several complications, some of them severe. A rare complication of this procedure is the accidental induced macular hole. A 54-year-old female patient was referred to our Department because of a severe loss of vision and a central scotoma at the right eye. The patient underwent a Nd:YAG posterior capsulotomy 2 days ago, for a PCO. The fundus examination at presentation revealed a round retinal defect in the macular region, a massive inferior preretinal hemorrhage and a mild vitreous hamorrhage. A 6-months follow-up of the case, including retinography and fluorescein angiography, is presented. Although the Nd:YAG laser capsulotomy is a safe, noninvasive, and effective outpatient procedure to improve vision hindered by PCO, it must be recognized that it carries a low but definite risk of serious complications. Physicians and patients should be aware of these rare but severe complications regarding this otherwise safe procedure. Fortunately, most of the complications related to this procedure are transient and can be managed by proper medication.

  11. Multifrequency Nd:YAG laser application for tumor fluorescence diagnosis

    NASA Astrophysics Data System (ADS)

    Yova, Dido M.; Halkiotis, Konstantinos N.; Manolopoulos, Athanassios; Ouzounoglou, Nikolaos K.; Hovhannisyan, Vladimir A.; Avanessian, Lia A.

    1999-12-01

    A computerized fiber-optic spectrofluorometer based on a multifrequency Nd:YAG laser ((lambda) equals 355, 440, 532 and 660 nm, f equals 25 Hz, E equals 1 - 10 mJ, (tau) equals 12 ns) for tissue fluorescence registration in vivo and ex vivo has been developed. The less intensive fluorescence from a tumor of Sarcoma-45 bearing animal model in comparison with the surrounding normal tissue was observed at the spectral region around 450 nm. The influence of reabsorption, energy transfer and other physical factors on tumor fluorescence, sensitized by Photohem (hematoporphyrin derivative), disodium salt of fluorescein (FL) and chlorin e6 (Chl) was investigated. The pharmacokinetic behavior of Chl in different organs and tumors of the animal models has been estimated. The most intensive Chl fluorescence of tumor tissue was observed at 18 hours after photosensitizer injection. The maximum of the tumor-to-healthy tissue ratio of fluorescence was reached 10 at 27 hours after pigment injection. The fluorescence spectra from different types of human tumors after i/v injection with FL or topical application of ALA were studied. A simple model of Nd:YAG laser system for tumor fluorescence diagnosis has been elaborated. Advantages of the laser fluorescence diagnosis of malignant tumors by solid state multifrequency Nd:YAG laser and the increase in accuracy and specificity of this method is discussed.

  12. Origin of Magnetic Properties in Amorphous Metals.

    DTIC Science & Technology

    1979-12-01

    Magnetic Properties of Fe-Ni-B Amorphous Alloys," F. E. Luborsky, J. L. Walter, and H. H. Liebermann , IEEE Trans. on Magnetics MAG-15, 909 (1979). Also GE...Report 78CRD132. 2. "Formation and Magnetic Properties of Fe-B-Si Amorphous Alloys," F. E. Luborsky, J. J. Becker, J. L. Walter, and H. H. Liebermann ...Amorphous Alloys," F. E. Luborsky and H. H. Liebermann , J. Appl. Phys., to appear. Also GE Report 79CRD177. 4. "The Effect of Temperature on Magnetic

  13. Characterization of mechanical heterogeneity in amorphous solids

    NASA Astrophysics Data System (ADS)

    Peng, H. L.; Li, M. Z.; Sun, B. A.; Wang, W. H.

    2012-07-01

    The structural geometry and size distribution of the local atomic rearrangements induced by external stress in amorphous solids are investigated by molecular dynamics studies. We find that the size distribution exhibits a generic power-law behavior and their structural geometry shows fractal feature. This indicates that the local atomic rearrangements in amorphous solids are self-organized during deformation. A simple theoretical model based on the interaction of the heterogeneous elastic field sources is proposed which predicts the power-law scaling and characterizes the properties of the local atomic rearrangements in amorphous solids.

  14. Laser irradiation to produce amorphous pharmaceuticals.

    PubMed

    Titapiwatanakun, Varin; Tankul, Junlathip; Basit, Abdul W; Gaisford, Simon

    2016-11-30

    Using a high-power CO2 laser to irradiate powder beds, it was possible to induce phase transformation to the amorphous state. Irradiation of a model drug, indometacin, resulted in formation of a glass. Varying the settings of the laser (power and raster speed) was shown to change the physicochemical properties of the glasses produced and all irradiated glasses were found to be more stable than a reference glass produced by melt-quenching. Irradiation of a powder blend of paracetamol and polyvinylpyrrolidone K30 was found to produce a solid amorphous dispersion. The results suggest that laser-irradiation might be a useful method for making amorphous pharmaceuticals.

  15. Photonic crystals, amorphous materials, and quasicrystals.

    PubMed

    Edagawa, Keiichi

    2014-06-01

    Photonic crystals consist of artificial periodic structures of dielectrics, which have attracted much attention because of their wide range of potential applications in the field of optics. We may also fabricate artificial amorphous or quasicrystalline structures of dielectrics, i.e. photonic amorphous materials or photonic quasicrystals. So far, both theoretical and experimental studies have been conducted to reveal the characteristic features of their optical properties, as compared with those of conventional photonic crystals. In this article, we review these studies and discuss various aspects of photonic amorphous materials and photonic quasicrystals, including photonic band gap formation, light propagation properties, and characteristic photonic states.

  16. Photonic crystals, amorphous materials, and quasicrystals

    PubMed Central

    Edagawa, Keiichi

    2014-01-01

    Photonic crystals consist of artificial periodic structures of dielectrics, which have attracted much attention because of their wide range of potential applications in the field of optics. We may also fabricate artificial amorphous or quasicrystalline structures of dielectrics, i.e. photonic amorphous materials or photonic quasicrystals. So far, both theoretical and experimental studies have been conducted to reveal the characteristic features of their optical properties, as compared with those of conventional photonic crystals. In this article, we review these studies and discuss various aspects of photonic amorphous materials and photonic quasicrystals, including photonic band gap formation, light propagation properties, and characteristic photonic states. PMID:27877676

  17. Processing and Characterization of Polycrystalline Yag (Yttrium Aluminum Garnet) Core-Clad Fibers - Postprint

    DTIC Science & Technology

    2015-01-01

    AFRL-RY-WP-TP-2014-0296 PROCESSING AND CHARACTERIZATION OF POLYCRYSTALLINE YAG ( YTTRIUM ALUMINUM GARNET) CORE-CLAD FIBERS -POSTPRINT...April 2013 – 1 April 2014 4. TITLE AND SUBTITLE PROCESSING AND CHARACTERIZATION OF POLYCRYSTALLINE YAG ( YTTRIUM ALUMINUM GARNET) CORE-CLAD FIBERS...of polycrystalline YAG ( Yttrium Aluminum Garnet) core-clad fibers Hyun Jun Kima,b, Geoff E. Faira*, Santeri A

  18. Temperature Dependence of a Diode-pumped Cryogenic Erbium (Er):Yttrium Aluminum Garnet (YAG) Laser

    DTIC Science & Technology

    2009-07-01

    Table 1. Temperature (T) dependence of the fluorescence lifetime of 0.5% Er:YAG, averaged over the two emission wavelengths...the laser is due to its attractive combination of spectroscopic and thermomechanical properties, and the resulting extensive development of YAG...minimize reabsorption for fluorescence spectra and lifetime data. A 2 atomic % Er:YAG single-crystal sample from Scientific Materials was fabricated to

  19. Amorphous to Amorphous Form Transitions of Water Ice and Astrophysical Implications

    NASA Technical Reports Server (NTRS)

    Jenniskens, Peter; Blake, David F.; Chang, Sherwood (Technical Monitor)

    1994-01-01

    We have combined Selected Area Electron Diffraction (SAED) and cryogenic techniques in an instrumental configuration that allows observing the structure of vapor deposited ice as it evolves during warmup. The ice is deposited in-situ inside an Hitachi H-500 H transmission electron microscope at a base pressure of 1-5 x 10(exp -7) torr on a thin amorphous carbon substrate at 15K or 86K and warmed up at a rate of 1-2 K/min. We find a progression of amorphous forms and well defined amorphous to amorphous transitions. Apart from the well known low-density form of ice, we confirm the presence of a high-density form and find a third amorphous form that coexists with cubic ice. We will report too on the amorphous to crystalline transition and the implications of these results for radical diffusion and gas retention observed in laboratory analog studies of interstellar and cometary ices.

  20. Effect of Water-Cooled Nd:YAG Laser on Dentinal Tubule Occlusion In Vitro.

    PubMed

    Xiao, Shimeng; Liang, Kunneng; Liu, Hongling; Zhang, Manling; Yang, Heng; Guo, Shujuan; Ding, Yi

    2017-02-01

    The objective of this study was to investigate the effect of a new water-cooled Nd:YAG laser on dentinal tubule occlusion. The effect of water-cooled Nd:YAG laser on dentinal tubule occlusion has not been reported. Acid-etched dentin samples were randomly divided into three groups: (1) dentin control, (2) dentin treated by Nd:YAG laser, (3) dentin treated by water-cooled Nd:YAG laser. After laser irradiation, half of the samples were immersed in a 6 wt% citric acid (pH 1.5) solution for 1 min to evaluate the acid resistance. The morphologies of dentin surfaces were characterized by scanning electron microscopy. The number and diameters of the open dentinal tubules were analyzed by one-way and two-way analyses of variance. Both the Nd:YAG laser and water-cooled Nd:YAG laser melted the superficial layer of dentin, which caused dentinal tubule occlusion in most areas and diameter reduction of the rest open tubules. Microcracks on the dentin surface were only observed in the Nd:YAG laser group. The tubule occlusion induced by the two lasers showed a good acid resistance. The effect of water-cooled Nd:YAG laser on dentinal tubule occlusion is similar to that of the Nd:YAG laser. The dentinal tubule occlusion induced by the two lasers could resist acid challenge to some extent.

  1. Amalgam Surface Treatment by Different Output Powers of Er:YAG Laser:SEM Evaluation.

    PubMed

    Hosseini, Mohammad Hashem; Hassanpour, Mehdi; Etemadi, Ardavan; Ranjbar Omrani, Ladan; Darvishpour, Hojat; Chiniforush, Nasim

    2015-01-01

    The purpose of this study was to evaluate amalgam surfaces treated by different output powers of erbium-doped yttrium aluminum garnet (Er:YAG) laser by scanning electron microscope (SEM). Twenty-one amalgam blocks (8 mm × 8 mm, 3 mm thickness) were prepared by condensing silver amalgam (into putty impression material. After keeping them for 24 hours in distilled water, they were divided into 7 groups as follow: G1: Er:YAG laser (1 W, 50 mJ), G2: Er:YAG laser (2 W, 100 mJ), G3: Er:YAG laser (3 W, 150 mJ), G4: Sandblast, G5: Sandblast + Er:YAG laser (1 W, 50 mJ), G6: Sandblast +Er:YAG laser (2 W, 100 mJ) and G7: Sandblast +Er:YAG laser (3 W, 150 mJ). Then after preparation of all samples, they were examined by SEM. The SEM results of amalgam surfaces treated by different output powers of Er:YAG laser showed some pitting areas with non-homogenous irregularities Conclusion: It seems that the application of sandblasting accompanied by Er:YAG laser irradiation can provide proper surface for bonding of orthodontic brackets.

  2. Amalgam Surface Treatment by Different Output Powers of Er:YAG Laser:SEM Evaluation

    PubMed Central

    Hosseini, Mohammad Hashem; Hassanpour, Mehdi; Etemadi, Ardavan; Ranjbar Omrani, Ladan; Darvishpour, Hojat; Chiniforush, Nasim

    2015-01-01

    Introduction: The purpose of this study was to evaluate amalgam surfaces treated by different output powers of erbium-doped yttrium aluminum garnet (Er:YAG) laser by scanning electron microscope (SEM). Methods: Twenty-one amalgam blocks (8 mm × 8 mm, 3 mm thickness) were prepared by condensing silver amalgam (into putty impression material. After keeping them for 24 hours in distilled water, they were divided into 7 groups as follow: G1: Er:YAG laser (1 W, 50 mJ), G2: Er:YAG laser (2 W, 100 mJ), G3: Er:YAG laser (3 W, 150 mJ), G4: Sandblast, G5: Sandblast + Er:YAG laser (1 W, 50 mJ), G6: Sandblast +Er:YAG laser (2 W, 100 mJ) and G7: Sandblast +Er:YAG laser (3 W, 150 mJ). Then after preparation of all samples, they were examined by SEM. Results: The SEM results of amalgam surfaces treated by different output powers of Er:YAG laser showed some pitting areas with non-homogenous irregularities Conclusion: It seems that the application of sandblasting accompanied by Er:YAG laser irradiation can provide proper surface for bonding of orthodontic brackets. PMID:26705463

  3. Power scaling of highly neodymium-doped YAG ceramic lasers with a bounce amplifier geometry

    NASA Astrophysics Data System (ADS)

    Omatsu, Takashige; Ojima, Yasukuni; Minassian, Ara; Damzen, Michael J.

    2005-09-01

    High power operation of highly-doped ceramic Nd:YAG laser is demonstrated using a laser diode transversely-pumped bounce geometry. Using a 2% doped ceramic Nd:YAG amplifier, an output power of 45W was achieved with 158W diode pumping. The cavity configuration was optimized for TEM00 operation and a high spatial quality output (M2 <1.5) was obtained at an output power of 27W. A ceramic Nd:YAG laser with 4% doping was operated at over 1 watt of output power. These are the highest power levels achieved in ceramic Nd:YAG lasers at >1% doping level.

  4. Gingival melanin depigmentation by Er:YAG laser: a literature review.

    PubMed

    Pavlic, Verica; Brkic, Zlata; Marin, Sasa; Cicmil, Smiljka; Gojkov-Vukelic, Mirjana; Aoki, Akira

    2017-10-06

    Laser ablation is recently suggested as a most effective and reliable technique for depigmentation of melanin hyperpigmented gingiva. To date, different lasers have been used for gingival depigmentation (CO2, diode, Nd:YAG, Er:YAG and Er,Cr:YSGG lasers). The use of Er:YAG laser for depigmentation of melanin hyperpigmented gingiva has gained increasing importance in recent years. The purpose of this study was to report removal of gingival melanin pigmentation using an Er:YAG laser in a literature review. The main outcomes, such as improvement of signs (clinical parameters of bleeding, erythema, swelling and wound healing), symptoms (pain) and melanin recurrence/repigmentation were measured. The literature demonstrated that depigmentation of gingival melanin pigmentation can be performed safely and effectively by Er:YAG laser resulting in healing and an esthetically significant improvement of gingival discoloration. Thus, Er:YAG laser seems to be safe and useful in melanin depigmentation procedure. However, the main issue in giving the final conclusion of the optimal Er:YAG laser use in melanin depigmentation is that, to date, studies are offering completely discrepant Er:YAG laser procedure protocols (complex settings of laser parameters), and different criteria for the assessment of depigmentation and repigmentation (recurrence), thus hampering the comparison of the results. Therefore, further studies are necessary to give an optimal recommendation on the use of Er:YAG laser in gingival melanin hyperpigmentation.

  5. 551 nm Generation by sum-frequency mixing of intracavity pumped Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Dong, Y.; Li, S. T.; Zhang, X. H.

    2012-02-01

    We present for the first time a Nd:YAG laser emitting at 1319 nm intracavity pumped by a 946 nm diode-pumped Nd:YAG laser. A 809 nm laser diode is used to pump the first Nd:YAG crystal emitting at 946 nm, and the second Nd:YAG laser emitting at 1319 nm intracavity pumped at 946 nm. Intracavity sumfrequency mixing at 946 and 1319 nm was then realized in a LBO crystal to reach the yellow range. We obtained a continuous-wave output power of 158 mW at 551 nm with a pump laser diode emitting 18.7 W at 809 nm.

  6. Tissue Heating With A Pulsed Nd-YAG Laser

    NASA Astrophysics Data System (ADS)

    Grossweiner, Leonard I.; Al-Karmi, Anan M.

    1988-06-01

    Neodymium-yttrium aluminum garnet (Nd-YAG) lasers are finding increasing appli-cations in laser surgery of vascular tissues because of their good hemostatic properties. Heat penetration is deeper than the carbon dioxide laser, because the 1064 nm Nd-YAG emission is located in a "window" between the strong absorptions of oxyhemoglobin and tissue water. The basic physics of laser-tissue interactions suggests that damage to peripheral tissues can be confined by using sufficiently short pulses. In continuous mode (CW) operation, heat flow driven by temperature gradients leads to tissue heating external to the optical absorption profile. When the energy is delivered in pulses, however, conductive heat flow is minimized if the pulse duration (tn) is shorter than the thermal relaxation time constant (t ). Pulsed operation should be especially useful for the Nd-YAG laser, where the 1/e optical penetration depth (5) at 1064 nm is the order of 0.3 to 0.5 cm. Taking t" =2/2a, where a is the thermal diffusivity (the order of 0.001 cm2/s for tissues), typical values of t* for heat conduction are the order of 1-2 min. Heat removal by blood flow augments thermal conduction in vascularized tissues. The rate of this process is characterized by 1/Q, where Q is the volume blood perfusion rate. Values 1/Q range from the order of 15 s for human kidney and thyroid to more than 15 min for muscle.1 Accordingly, heat removal by conduction and blood flow during the pulse duration can be neglected for many tissues exposed to Nd-YAG laser pulses. This paper describes an analytical solution to the two dimensional laser bioheat equation applicable to pulsed operation. The theory was applied to measur-ements on potato tuber heated by low-power pulses from a clinical Nd-YAG laser. The initial temperature elevations are in satisfactory agreement with the analysis, but thermal relaxation was faster than predicted. The suggested explanation for the discrepancy involves evaporative heat transfer to

  7. Corrosion resistant amorphous metals and methods of forming corrosion resistant amorphous metals

    DOEpatents

    Farmer, Joseph C.; Wong, Frank M. G.; Haslam, Jeffery J.; Yang, Nancy; Lavernia, Enrique J.; Blue, Craig A.; Graeve, Olivia A.; Bayles, Robert; Perepezko, John H.; Kaufman, Larry; Schoenung, Julie; Ajdelsztajn, Leo

    2009-11-17

    A system for coating a surface comprises providing a source of amorphous metal, providing ceramic particles, and applying the amorphous metal and the ceramic particles to the surface by a spray. The coating comprises a composite material made of amorphous metal that contains one or more of the following elements in the specified range of composition: yttrium (.gtoreq.1 atomic %), chromium (14 to 18 atomic %), molybdenum (.gtoreq.7 atomic %), tungsten (.gtoreq.1 atomic %), boron (.ltoreq.5 atomic %), or carbon (.gtoreq.4 atomic %).

  8. Corrosion resistant amorphous metals and methods of forming corrosion resistant amorphous metals

    DOEpatents

    Farmer, Joseph C.; Wong, Frank M.G.; Haslam, Jeffery J.; Yang, Nancy; Lavernia, Enrique J.; Blue, Craig A.; Graeve, Olivia A.; Bayles, Robert; Perepezko, John H.; Kaufman, Larry; Schoenung, Julie; Ajdelsztajn, Leo

    2014-07-15

    A system for coating a surface comprises providing a source of amorphous metal, providing ceramic particles, and applying the amorphous metal and the ceramic particles to the surface by a spray. The coating comprises a composite material made of amorphous metal that contains one or more of the following elements in the specified range of composition: yttrium (.gtoreq.1 atomic %), chromium (14 to 18 atomic %), molybdenum (.gtoreq.7 atomic %), tungsten (.gtoreq.1 atomic %), boron (.ltoreq.5 atomic %), or carbon (.gtoreq.4 atomic %).

  9. Amorphization of Silicon Carbide by Carbon Displacement

    SciTech Connect

    Devanathan, Ram; Gao, Fei; Weber, William J.

    2004-05-10

    We have used molecular dynamics simulations to examine the possibility of amorphizing silicon carbide (SiC) by exclusively displacing C atoms. At a defect generation corresponding to 0.2 displacements per atom, the enthalpy surpasses the level of melt-quenched SiC, the density decreases by about 15%, and the radial distribution function shows a lack of long-range order. Prior to amorphization, the surviving defects are mainly C Frenkel pairs (67%), but Si Frenkel pairs (18%) and anti-site defects (15%) are also present. The results indicate that SiC can be amorphized by C sublattice displacements. Chemical short-range disorder, arising mainly from interstitial production, plays a significant role in the amorphization.

  10. Association of Er:YAG and Nd:YAG irradiation for apicoectomy and retrofilling cavity preparation compared to conventional technique: a permeability study

    NASA Astrophysics Data System (ADS)

    Camargo, Selma C. C.; Gavini, Giulio; Eduardo, Carlos d. P.; Aun, Carlos E.; Ribeiro, Luciano W.; Coil, Jeffrey M.

    1999-05-01

    The aim of this research was to evaluate dentin permeability effects at the apical cut surface prepared with Er:YAG laser and irradiated with Nd:YAG laser compared to conventional techniques. 62 extracted human teeth were divided into four groups of 7 teeth each. For Group 1 apicoectomy was performed using high speed handpiece and diamond burs. Group 2 was prepared as group 1 and lased with Nd:YAG (1W,15Hz of energy before retrograde cavity filling). For group 3 Er:YAG* laser irradiation (wavelength of 2.94μm, pulse width of 250-500μs)was used in 400mJ of energy, frequency of 6Hz, on focus mode under distilled water refrigeration and group 4 was performed as group 3 and lased with Nd:YAG (1W, 15Hz of energy before retrograde cavity filling). Permeability was evaluated by the extent of methylene blue dye penetration into the tubules. There were statistically significant differences in permeability between groups. Nd:YAG laser irradiation significantly reduced apical dentin permeability when compared to unlased groups. Er:YAG laser by itself showed higher percentage of dye penetration.

  11. Amorphous Phases on the Surface of Mars

    NASA Technical Reports Server (NTRS)

    Rampe, E. B.; Morris, R. V.; Ruff, S. W.; Horgan, B.; Dehouck, E.; Achilles, C. N.; Ming, D. W.; Bish, D. L.; Chipera, S. J.

    2014-01-01

    Both primary (volcanic/impact glasses) and secondary (opal/silica, allophane, hisingerite, npOx, S-bearing) amorphous phases appear to be major components of martian surface materials based on orbital and in-situ measurements. A key observation is that whereas regional/global scale amorphous components include altered glass and npOx, local scale amorphous phases include hydrated silica/opal. This suggests widespread alteration at low water-to-rock ratios, perhaps due to snow/ice melt with variable pH, and localized alteration at high water-to-rock ratios. Orbital and in-situ measurements of the regional/global amorphous component on Mars suggests that it is made up of at least three phases: npOx, amorphous silicate (likely altered glass), and an amorphous S-bearing phase. Fundamental questions regarding the composition and the formation of the regional/global amorphous component(s) still remain: Do the phases form locally or have they been homogenized through aeolian activity and derived from the global dust? Is the parent glass volcanic, impact, or both? Are the phases separate or intimately mixed (e.g., as in palagonite)? When did the amorphous phases form? To address the question of source (local and/or global), we need to look for variations in the different phases within the amorphous component through continued modeling of the chemical composition of the amorphous phases in samples from Gale using CheMin and APXS data. If we find variations (e.g., a lack of or enrichment in amorphous silicate in some samples), this may imply a local source for some phases. Furthermore, the chemical composition of the weathering products may give insight into the formation mechanisms of the parent glass (e.g., impact glasses contain higher Al and lower Si [30], so we might expect allophane as a weathering product of impact glass). To address the question of whether these phases are separate or intimately mixed, we need to do laboratory studies of naturally altered samples made

  12. Ion-beam amorphization of semiconductors: A physical model based on the amorphous pocket population

    SciTech Connect

    Mok, K.R.C.; Jaraiz, M.; Martin-Bragado, I.; Rubio, J.E.; Castrillo, P.; Pinacho, R.; Barbolla, J.; Srinivasan, M.P.

    2005-08-15

    We introduce a model for damage accumulation up to amorphization, based on the ion-implant damage structures commonly known as amorphous pockets. The model is able to reproduce the silicon amorphous-crystalline transition temperature for C, Si, and Ge ion implants. Its use as an analysis tool reveals an unexpected bimodal distribution of the defect population around a characteristic size, which is larger for heavier ions. The defect population is split in both size and composition, with small, pure interstitial and vacancy clusters below the characteristic size, and amorphous pockets with a balanced mixture of interstitials and vacancies beyond that size.

  13. Amorphization strategy affects the stability and supersaturation profile of amorphous drug nanoparticles.

    PubMed

    Cheow, Wean Sin; Kiew, Tie Yi; Yang, Yue; Hadinoto, Kunn

    2014-05-05

    Amorphous drug nanoparticles have recently emerged as a promising bioavailability enhancement strategy of poorly soluble drugs attributed to the high supersaturation solubility generated by the amorphous state and fast dissolution afforded by the nanoparticles. Herein we examine the effects of two amorphization strategies in the nanoscale, i.e., (1) molecular mobility restrictions and (2) high energy surface occupation, both by polymer excipient stabilizers, on the (i) morphology, (ii) colloidal stability, (iii) drug loading, (iv) amorphous state stability after three-month storage, and (v) in vitro supersaturation profiles, using itraconazole (ITZ) as the model drug. Drug-polyelectrolyte complexation is employed in the first strategy to prepare amorphous ITZ nanoparticles using dextran sulfate as the polyelectrolyte (ITZ nanoplex), while the second strategy employs pH-shift precipitation using hydroxypropylmethylcellulose as the surface stabilizer (nano-ITZ), with both strategies resulting in >90% ITZ utilization. Both amorphous ITZ nanoparticles share similar morphology (∼300 nm spheres) with the ITZ nanoplex exhibiting better colloidal stability, albeit at lower ITZ loading (65% versus 94%), due to the larger stabilizer amount used. The ITZ nanoplex also exhibits superior amorphous state stability, attributed to the ITZ molecular mobility restriction by electrostatic complexation with dextran sulfate. The higher stability, however, is obtained at the expense of slower supersaturation generation, which is maintained over a prolonged period, compared to the nano-ITZ. The present results signify the importance of selecting the optimal amorphization strategy, in addition to formulating the excipient stabilizers, to produce amorphous drug nanoparticles having the desired characteristics.

  14. Comparative evaluation of root surface after manual instrumentation with and without Er:YAG laser as an auxiliary therapy: in-vitro study

    NASA Astrophysics Data System (ADS)

    Lizarelli, Rosane F. Z.; Ferreira, Zulene A.; Torquato, Tatiana M.; Sampaio, Jose E. C.; Bagnato, Vanderlei S.

    2000-03-01

    One of the most important difficulty in the periodontal disease treatment resides in the impossibility of decontamination of roots just affected by the periodontal disease through mechanical tools. Manual dental scaling results in the amorphous material without continuity solution due to the dental cut, denominated smear layer. The main purpose of the present study was to evaluate the structure of the radicular surface using two methods for periodontal treatments: manual and mechanical associated to the irrigation with water and with EDTA (ethylene diamine tetracycline acid), followed by the application of the Er:YAG laser or the same without laser. Thirty teeth were selected with periodontal involvement. The radicular surface was scraped with ultrasound and planed vigorously, with manual instrumentation. The teeth were divided ramdomically in several groups: GI -- control, just manual instrumentation and water irrigation; GII -- manual instrumentation, EDTA irrigation; GIII -- manual instrumentation, EDTA irrigation, Er:YAG laser irradiation; GIV -- manual instrumentation, laser irradiation; and, GV -- manual instrumentation, laser irradiation and EDTA. Kruskall Wallis statistical test was applied and shows that there was not significance difference at the level of 5% among the five groups, however, when the groups were compared in pairs, GII X GIV and GII X GV shows difference in 5%, and GI X GII, difference at 1% level. The results show equivalence around the used methodology.

  15. Using containerless methods to develop amorphous pharmaceuticals.

    PubMed

    Weber, J K R; Benmore, C J; Suthar, K J; Tamalonis, A J; Alderman, O L G; Sendelbach, S; Kondev, V; Yarger, J; Rey, C A; Byrn, S R

    2017-01-01

    Many pipeline drugs have low solubility in their crystalline state and require compounding in special dosage forms to increase bioavailability for oral administration. The use of amorphous formulations increases solubility and uptake of active pharmaceutical ingredients. These forms are rapidly gaining commercial importance for both pre-clinical and clinical use. Synthesis of amorphous drugs was performed using an acoustic levitation containerless processing method and spray drying. The structure of the products was investigated using in-situ high energy X-ray diffraction. Selected solvents for processing drugs were investigated using acoustic levitation. The stability of amorphous samples was measured using X-ray diffraction. Samples processed using both spray drying and containerless synthesis were compared. We review methods for making amorphous pharmaceuticals and present data on materials made by containerless processing and spray drying. It was shown that containerless processing using acoustic levitation can be used to make phase-pure forms of drugs that are known to be difficult to amorphize. The stability and structure of the materials was investigated in the context of developing and making clinically useful formulations. Amorphous compounds are emerging as an important component of drug development and for the oral delivery of drugs with low solubility. Containerless techniques can be used to efficiently synthesize small quantities of pure amorphous forms that are potentially useful in pre-clinical trials and for use in the optimization of clinical products. Developing new pharmaceutical products is an essential enterprise to improve patient outcomes. The development and application of amorphous pharmaceuticals to increase absorption is rapidly gaining importance and it provides opportunities for breakthrough research on new drugs. There is an urgent need to solve problems associated with making formulations that are both stable and that provide high

  16. A Magnetic Sensor with Amorphous Wire

    PubMed Central

    He, Dongfeng; Shiwa, Mitsuharu

    2014-01-01

    Using a FeCoSiB amorphous wire and a coil wrapped around it, we have developed a sensitive magnetic sensor. When a 5 mm long amorphous wire with the diameter of 0.1 mm was used, the magnetic field noise spectrum of the sensor was about 30 pT/√Hz above 30 Hz. To show the sensitivity and the spatial resolution, the magnetic field of a thousand Japanese yen was scanned with the magnetic sensor. PMID:24940865

  17. Picosecond Electronic Relaxations In Amorphous Semiconductors

    NASA Astrophysics Data System (ADS)

    Tauc, Jan

    1983-11-01

    Using the pump and probe technique the relaxation processes of photogenerated carriers in amorphous tetrahedral semiconductors and chalcogenide glasses in the time domain from 0.5 Ps to 1.4 ns have been studied. The results obtained on the following phenomena are reviewed: hot carrier thermalization in amorphous silicon; trapping of carriers in undoped a-Si:H; trapping of carriers in deep traps produced by doping; geminate recombination in As2S3-xSex glasses.

  18. Tests Of Amorphous-Silicon Photovoltaic Modules

    NASA Technical Reports Server (NTRS)

    Ross, Ronald G., Jr.

    1988-01-01

    Progress in identification of strengths and weaknesses of amorphous-silicon technology detailed. Report describes achievements in testing reliability of solar-power modules made of amorphous-silicon photovoltaic cells. Based on investigation of modules made by U.S. manufacturers. Modules subjected to field tests, to accelerated-aging tests in laboratory, and to standard sequence of qualification tests developed for modules of crystalline-silicon cells.

  19. Amorphous Carbon-Boron Nitride Nanotube Hybrids

    NASA Technical Reports Server (NTRS)

    Kim, Jae Woo (Inventor); Siochi, Emilie J. (Inventor); Wise, Kristopher E. (Inventor); Lin, Yi (Inventor); Connell, John (Inventor)

    2016-01-01

    A method for joining or repairing boron nitride nanotubes (BNNTs). In joining BNNTs, the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures. In repairing BNNTs, the damaged site of the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures at the damage site.

  20. Thermal transport in amorphous materials: a review

    NASA Astrophysics Data System (ADS)

    Wingert, Matthew C.; Zheng, Jianlin; Kwon, Soonshin; Chen, Renkun

    2016-11-01

    Thermal transport plays a crucial role in performance and reliability of semiconductor electronic devices, where heat is mainly carried by phonons. Phonon transport in crystalline semiconductor materials, such as Si, Ge, GaAs, GaN, etc, has been extensively studied over the past two decades. In fact, study of phonon physics in crystalline semiconductor materials in both bulk and nanostructure forms has been the cornerstone of the emerging field of ‘nanoscale heat transfer’. On the contrary, thermal properties of amorphous materials have been relatively less explored. Recently, however, a growing number of studies have re-examined the thermal properties of amorphous semiconductors, such as amorphous Si. These studies, which included both computational and experimental work, have revealed that phonon transport in amorphous materials is perhaps more complicated than previously thought. For instance, depending on the type of amorphous materials, thermal transport occurs via three types of vibrations: propagons, diffusons, and locons, corresponding to the propagating, diffusion, and localized modes, respectively. The relative contribution of each of these modes dictates the thermal conductivity of the material, including its magnitude and its dependence on sample size and temperature. In this article, we will review the fundamental principles and recent development regarding thermal transport in amorphous semiconductors.

  1. Amorphous boron nitride at high pressure

    NASA Astrophysics Data System (ADS)

    Durandurdu, Murat

    2016-06-01

    The pressure-induced phase transformation in hexagonal boron nitrite and amorphous boron nitrite is studied using ab initio molecular dynamics simulations. The hexagonal-to-wurtzite phase transformation is successfully reproduced in the simulation with a transformation mechanism similar to one suggested in experiment. Amorphous boron nitrite, on the other hand, gradually transforms to a high-density amorphous phase with the application of pressure. This phase transformation is irreversible because a densified amorphous state having both sp3 and sp2 bonds is recovered upon pressure release. The high-density amorphous state mainly consists of sp3 bonds and its local structure is quite similar to recently proposed intermediate boron nitrite phases, in particular tetragonal structure (P42/mnm), rather than the known the wurtzite or cubic boron nitrite due to the existence of four membered rings and edge sharing connectivity. On the basis of this finding we propose that amorphous boron nitrite might be best candidate as a starting structure to synthesize the intermediate phase(s) at high pressure and temperature (probably below 800 °C) conditions.

  2. Wear Resistant Amorphous and Nanocomposite Steel Coatings

    SciTech Connect

    Branagan, Daniel James; Swank, William David; Haggard, Delon C; Fincke, James Russell; Sordelet, D.

    2001-10-01

    In this article, amorphous and nanocomposite thermally deposited steel coatings have been formed by using both plasma and high-velocity oxy-fuel (HVOF) spraying techniques. This was accomplished by developing a specialized iron-based composition with a low critical cooling rate (?104 K/s) for metallic glass formation, processing the alloy by inert gas atomization to form micron-sized amorphous spherical powders, and then spraying the classified powder to form coatings. A primarily amorphous structure was formed in the as-sprayed coatings, independent of coating thickness. After a heat treatment above the crystallization temperature (568°C), the structure of the coatings self-assembled (i.e., devitrified) into a multiphase nanocomposite microstructure with 75 to 125 nm grains containing a distribution of 20 nm second-phase grain-boundary precipitates. Vickers microhardness testing revealed that the amorphous coatings were very hard (10.2 to 10.7 GPa), with further increases in hardness after devitrification (11.4 to 12.8 GPa). The wear characteristics of the amorphous and nanocomposite coatings were determined using both two-body pin-on-disk and three-body rubber wheel wet-slurry sand tests. The results indicate that the amorphous and nanocomposite steel coatings are candidates for a wide variety of wear-resistant applications.

  3. Neutron irradiation induced amorphization of silicon carbide

    NASA Astrophysics Data System (ADS)

    Snead, L. L.; Hay, J. C.

    1999-07-01

    This paper provides the properties of bulk stoichiometric silicon carbide which has been amorphized under neutron irradiation. Both high purity single crystal hcp and high purity, highly faulted (cubic) chemically vapor deposited (CVD) SiC were irradiated at approximately 60°C to a total fast neutron fluence of 2.6 × 10 25 n/m 2. Amorphization was seen in both materials as evidenced by TEM, electron diffraction and X-ray diffraction techniques. Physical properties for the amorphized single crystal material are reported including large changes in density (-10.8%), elastic modulus as measured using a nanoindentation technique (-45%), hardness as measured by nanoindentation (-45%), and standard Vickers hardness (-24%). Similar property changes are observed for the amorphized CVD SiC. Using measured thermal conductivity data for the CVD SiC sample, the critical temperature for amorphization at this neutron dose and flux, above which amorphization is not possible, is estimated to be greater than ˜125°C.

  4. Amorphous calcium (ortho)phosphates.

    PubMed

    Dorozhkin, Sergey V

    2010-12-01

    Amorphous calcium phosphates (ACPs) represent a unique class of biomedically relevant calcium orthophosphate salts, having variable chemical but essentially identical glass-like physical properties, in which there is neither translational nor orientational long-range ordering of the atomic positions. Normally, ACPs are the first solid phases, precipitated after a rapid mixing of aqueous solutions containing ions of Ca(2+) and PO₄³⁻; however, other production techniques are known. Interestingly, ACPs prepared by wet-chemical techniques were found to have a relatively constant chemical composition over a relatively wide range of preparation conditions, which suggests the presence of a well-defined local structural unit, presumably with the structure of Ca₉(PO₄)₆ - so-called Posner cluster. However, the presence of similar clusters in ACPs produced by other techniques remains uncertain. All ACPs are thermodynamically unstable compounds and, unless stored in dry conditions or doped by stabilizers, spontaneously tend to transform to crystalline calcium orthophosphates, mainly to calcium apatites. This solution instability of ACPs and their easy transformation to crystalline phases are of a great biological relevance. Specifically, the initiating role ACPs play in matrix vesicle biomineralization raises the importance of ACPs from a mere laboratory curiosity to that of a key intermediate in skeletal calcification. In addition, due to significant chemical and structural similarities with calcified mammalian tissues, as well as excellent biocompatibility and bioresorbability, all types of ACPs are very promising candidates for the manufacture of artificial bone grafts. This review summarizes the current knowledge on the occurrence, preparation, composition, structure, major properties and biomedical applications of ACPs. To assist readers in looking for the specific details on ACPs, a great number of references have been collected and systematized. Copyright

  5. Electrons and phonons in amorphous semiconductors

    NASA Astrophysics Data System (ADS)

    Prasai, Kiran; Biswas, Parthapratim; Drabold, D. A.

    2016-07-01

    The coupling between lattice vibrations and electrons is one of the central concepts of condensed matter physics. The subject has been deeply studied for crystalline materials, but far less so for amorphous and glassy materials, which are among the most important for applications. In this paper, we explore the electron-lattice coupling using current tools of a first-principles computer simulation. We choose three materials to illustrate the phenomena: amorphous silicon (a-Si), amorphous selenium (a-Se) and amorphous gallium nitride (a-GaN). In each case, we show that there is a strong correlation between the localization of electron states and the magnitude of thermally induced fluctuations in energy eigenvalues obtained from the density-functional theory (i.e. Kohn-Sham eigenvalues). We provide a heuristic theory to explain these observations. The case of a-GaN, a topologically disordered partly ionic insulator, is distinctive compared to the covalent amorphous examples. Next, we explore the consequences of changing the charge state of a system as a proxy for tracking photo-induced structural changes in the materials. Where transport is concerned, we lend insight into the Meyer-Neldel compensation rule and discuss a thermally averaged Kubo-Greenwood formula as a means to estimate electrical conductivity and especially its temperature dependence. We close by showing how the optical gap of an amorphous semiconductor can be computationally engineered with the judicious use of Hellmann-Feynman forces (associated with a few defect states) using molecular dynamics simulations. These forces can be used to close or open an optical gap, and identify a structure with a prescribed gap. We use the approach with plane-wave density functional methods to identify a low-energy amorphous phase of silicon including several coordination defects, yet with a gap close to that of good quality a-Si models.

  6. Two-Pass, Diode-Pumped Nd:YAG Slab Laser Head

    NASA Technical Reports Server (NTRS)

    Coyle, D. Barry

    1992-01-01

    Neodymium/yttrium aluminum garnet (Nd:YAG) ring-laser head designed for compactness, simplicity, and increased efficiency for side pumping by diode lasers. Laser head includes two linear arrays of diode lasers, two fused-silica collimating rods, and Nd:YAG slab. Slab mounted on finned copper block, providing good thermal dissipation.

  7. Histological and TEM examination of early stages of bone healing after Er:YAG laser irradiation.

    PubMed

    Pourzarandian, Amir; Watanabe, Hisashi; Aoki, Akira; Ichinose, Shizuko; Sasaki, Katia M; Nitta, Hiroshi; Ishikawa, Isao

    2004-08-01

    The aim of this study was to analyze the early healing process of bone tissue irradiated by Er:YAG laser and compare it with that treated by mechanical drilling and CO(2) laser. Er:YAG laser has a great potential for cutting hard tissues as it is capable of ablation with less thermal damage. Twenty-four male Wistar rats were used for this study. The calvarial bone of rats was exposed and straight grooves were prepared by Er:YAG laser, mechanical bur and continuous wave CO(2) laser. Four rats each were sacrificed at six time points: 10 min, 6 and 24 h and 3, 7, and 14 days post-surgery. Sections were prepared for light and transmission electron microscopic (TEM) observations. Compared to mechanical bur and CO(2) groups, the inflammatory cell infiltration adjacent to the irradiated bone surface, fibroblastic reaction, and revascularization were more pronounced in the Er:YAG laser-irradiated tissues. A cell-rich granulation tissue with fibroblasts and osteoblasts was predominant in 7-day specimens of Er:YAG laser group. Histopathological analysis of 14-day specimens in the Er:YAG group also revealed significantly greater new bone formation, compared with the mechanical bur and CO(2) laser groups. Initial bone healing following Er:YAG laser irradiation occurred faster than that after mechanical bur and CO(2) laser. Er:YAG laser treatment may be advantageous for wound healing of bone tissue, presumably by providing a favorable surface for cell attachment.

  8. Optimal power settings for Holmium:YAG lithotripsy.

    PubMed

    Sea, Jason; Jonat, Lee M; Chew, Ben H; Qiu, Jinze; Wang, Bingqing; Hoopman, John; Milner, Thomas; Teichman, Joel M H

    2012-03-01

    We determined the optimal Ho:YAG lithotripsy power settings to achieve maximal fragmentation, minimal fragment size and minimal retropulsion. Stone phantoms were irradiated in water with a Ho:YAG laser using a 365 μm optical fiber. Six distinct power settings were tested, including 0.2 to 2.0 J and 10 to 40 Hz. For all cohorts 500 J total radiant energy were delivered. A seventh cohort (0.2 J 40 Hz) was tested post hoc to a total energy of 1,250 J. Two experimental conditions were tested, including with and without phantom stabilization. Total fragmentation, fragment size and retropulsion were characterized. In mechanism experiments using human calculi we measured crater volume by optical coherence tomography and pressure transients by needle hydrophone across similar power settings. Without stabilization increased pulse energy settings produced increased total fragmentation and increased retropulsion (each p <0.0001). Fragment size was smallest for the 0.2 J cohorts (p <0.02). With stabilization increased pulse energy settings produced increased total fragmentation and increased retropulsion but also increased fragment size (each p <0.0001). Craters remained symmetrical and volume increased as pulse energy increased. Pressure transients remained modest at less than 30 bars even at 2.0 J pulse energy. Holmium:YAG lithotripsy varies as pulse energy settings vary. At low pulse energy (0.2 J) less fragmentation and retropulsion occur and small fragments are produced. At high pulse energy (2.0 J) more fragmentation and retropulsion occur with larger fragments. Anti-retropulsion devices produce more efficient lithotripsy, particularly at high pulse energy. Optimal lithotripsy laser dosimetry depends on the desired outcome. Copyright © 2012 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  9. New technique for prostatectomy using Ho:YAG laser

    NASA Astrophysics Data System (ADS)

    Daidoh, Yuichiro; Arai, Tsunenori; Murai, Masaru; Nakajima, Akio; Tsuji, Akira; Odajima, Kunio; Nakajima, Fumio; Kikuchi, Makoto; Nakamura, Hiroshi

    1994-05-01

    To develop a new transperineal laser prostatectomy through a biopsy needle, we determined the efficiency of a pulsed Nd:YAG laser irradiation for canine prostate. The Ho:YAG laser ((lambda) equals 2.1 micrometers ) may induced stress-wave to destroy the small vessels in prostate. After the exposure of the canine prostate, it was punctured by the needle. A quartz fiber of which core-diameter was 200 or 400 micrometers was inserted into the 18 G needle. The irradiation fluence was set to 150 - 600 J/cm2 and repetition rate was kept at 2 Hz. The cross-section of the irradiated portion of the prostate extracted immediately after the irradiation showed dark-colored hemorrhage layer around the ablation tract with 1 - 2 mm thickness. Some hemorrhage was histologically seen in stoma and gland in the irradiated prostate. In the case of 150 - 175 J/cm2 in the irradiation fluence, the irradiated portion of the prostate was found in the wedge-shaped area with brown color at one week after the irradiation. The lymphocytes infiltrating into the wedge-shaped zone were found. The wedge- shaped zone spread over the prostate and the change of urethral mucosa was minimum at one month after the irradiation. In the case of 500 - 600 J/cm2 irradiation, the paraurethral cavity was made at one month after the irradiation. The histological examination showed that the hemorrhage and subsequent histological changes may be caused by the laser induced stress-wave rather than thermal effect. Our results suggest that transperineal irradiation of pulsed Ho:YAG might offer an effective treatment for benign prostatic hyperplasia with the minimal damage to the urethral mucosa.

  10. Vitreous humor rheology after Nd:YAG laser photo disruption.

    PubMed

    Abdelkawi, Salwa A; Abdel-Salam, Ahmed M; Ghoniem, Dina F; Ghaly, Sally K

    2014-03-01

    This work aimed to consider the hazardous side effect of eye floaters treatment with Q-switched Nd:YAG laser on the protein and viscoelastic properties of the vitreous humor, and evaluate the protective role of vitamin C against laser photo disruption. Five groups of New Zealand rabbits were divided as follows: control group for (n = 3) without any treatment, the second group (n = 9) treated with Q-switched Nd:YAG laser energy of 5 mJ × 100 pulse delivered to the anterior, middle, and posterior vitreous, respectively (n = 3 for each). The third group (n = 9) received a daily dose of 25 mg/kg body weight vitamin C for 2 weeks, and then treated with laser as the previous group. The fourth group (n = 9) treated with 10 mJ 9 50 pulse delivered to the anterior, middle, and posterior vitreous, respectively (n = 3 rabbits each). The fifth group (n = 9) received a daily dose of 25 mg/kg body weight vitamin C for 2 weeks, and then treated with laser as the previous group. After 2 weeks of laser treatment, the protein content, refractive index (RI), and the rheological properties of vitreous humor, such as consistency, shear stress, and viscosity, were determined. The results showed that, the anterior vitreous group exposed to of 5 mJ × 100 pulse and/or supplemented with vitamin C, showed no obvious change. Furthermore, all other treated groups especially for mid-vitreous and posterior vitreous humor showed increase in the protein content, RI and the viscosity of vitreous humor. The flow index remained below unity indicating the non-Newtonian behavior of the vitreous humor. Application of Q-switched Nd:YAG laser should be restricted to the anterior vitreous humor to prevent the deleterious effect of laser on the gel state of the vitreous humor.

  11. Transmission of Er:YAG laser through different dental ceramics.

    PubMed

    Sari, Tugrul; Tuncel, Ilkin; Usumez, Aslihan; Gutknecht, Norbert

    2014-01-01

    The aim of this study was to determine the erbium-doped yttrium aluminum garnet (Er:YAG) laser transmission ratio through different dental ceramics with different thicknesses. Laser debonding procedure of adhesively luted all-ceramic restorations is based on the transmission of laser energy through the ceramic and the ablation of resin cement, because of the transmitted laser energy. Five different dental ceramics were evaluated in this study: sintered zirconium-oxide core ceramic, monolithic zirconium-oxide ceramic, feldspathic ceramic, leucite-reinforced glass ceramic, and lithium disilicate-reinforced glass ceramic. Two ceramic discs with different thicknesses (0.5 and 1 mm) were fabricated for each group. Ceramic discs were placed between the sensor membrane of the laser power meter and the tip of the contact handpiece of an Er:YAG laser device with the aid of a custom- made acrylic holder. The transmission ratio of Er:YAG laser energy (500 mJ, 2 Hz, 1 W, 1000 μs) through different ceramic discs was measured with the power meter. Ten measurements were made for each group and the results were analyzed with two way analysis of variance (ANOVA) and Tukey honestly significant difference (HSD) tests. The highest transmission ratio was determined for lithium disilicate-reinforced ceramic with 0.5 mm thickness (88%) and the lowest was determined for feldspathic ceramic with 1 mm thickness (44%). The differences among the different ceramics and between the different thicknesses were significant (p<0.05). Ceramic type and thickness should be taken into consideration to adjust the laser irradiation parameters during laser debonding of adhesively luted all-ceramic restorations.

  12. Thulium-YAG laser sialendoscopy for parotid and submandibular sialolithiasis.

    PubMed

    Durbec, M; Dinkel, E; Vigier, S; Disant, F; Marchal, F; Faure, F

    2012-12-01

    To evaluate the efficacy and safety of thulium-YAG laser in sialendoscopic fragmentation of salivary lithiasis. Retrospective, interventional case series. Sixty-three patients treated by interventional sialendoscopy with thulium-Yag laser fragmentation between 2003 and 2010 at Edouard Herriot Hospital were included in the study. The laser was used for non-floating or large lithiasis (>4 mm). The sialendoscopic thulium fiber laser was used in a pulsed mode with an average power output of 2-8 W to fragment and facilitate extraction of salivary stones. Several variables were studied: success rate, total number of procedures, total energy per procedure, size and number of salivary stones removed, and complications. Our series of 63 cases includes 40 cases of parotid lithiasis and 23 cases of submandibular lithiasis. In nine cases, two sessions of laser were performed. Stone size was evaluated pre-operatively by ultrasound and varied between 2 and 18 mm. Laser fragmentation was possible in every case. Complete extraction of the lithiasis was possible in 51 cases (73.9%) and partial extraction in eight cases (12.6%). Extraction failed in four cases (6.3%). Mean stone size was 5.4 mm (5.7 mm for parotid glands and 5.0 mm for sub-mandibular glands) and mean energy per procedure was 1,450 J (range: 1,400-1,800 J). Ductal perforations were observed in 12.7% of the cases. 65.1% of patients were free of symptoms with a mean follow-up of 18 months. Thulium-YAG laser appears to be an effective and safe technique in the treatment of salivary lithiasis. Copyright © 2012 Wiley Periodicals, Inc.

  13. Er:YAG crystal temperature influence on laser output characteristics

    NASA Astrophysics Data System (ADS)

    Němec, Michal; Å ulc, Jan; Hubka, Zbyněk.; Hlinomaz, Kryštof; Jelínková, Helena

    2017-02-01

    The main goal of this work was to investigate the influence of the temperature of the Er:YAG active medium on laser properties in eye-safe spectral region for three various pump wavelengths. The tested Er:YAG sample doped by 0.5% of Er3+ ions had a cylindrical shape with 25mm in length and 5mm in diameter. The absorption spectrum of the Er:YAG active medium in the range from 1400nm up to 1700nm for temperatures 80K and 300K was measured. The crystal was placed inside the vacuum chamber of a liquid nitrogen cooled cryostat. The temperature was controlled within the 80 - 340K temperature range. Three pump sources generating at 1535, 1452, and 1467nm were applied. The first one was flash lamp pumped Er:glass laser (repetition rate 0.5 Hz, pulse duration 1 ms, pulse energy 148 mJ). The further two sources were fiber coupled laser diodes (repetition rate 10 Hz, pulse duration 10 ms, maximum pulse energies 106mJ and 195 mJ). The semi-hemispherical laser resonator consisted of a pump curved mirror and output plan coupler with a reflectivity of 90% @ 1645 nm. The laser output characteristics were investigated in dependence on temperature of active medium for three laser pumping systems. The output energy has an optimum in dependence on active medium temperature and pump wavelengths. The maximal generated laser energies were 16.2mJ (90 K), 28.7mJ (120 K), and 33.2mJ (220 K), for pump wavelengths 1452 nm, 1467 nm, and 1535 nm, respectively.

  14. Holmium:YAG laser: effects on dentin demineralization

    NASA Astrophysics Data System (ADS)

    Holt, Raleigh A.; Nordquist, Robert E.

    1995-05-01

    The Holmium:YAG laser at 2.12 microns wavelength was used to compare the changes in resistance to demineralization of the dentinal root surfaces of human extracted teeth in vitro. Three protocols were used: Group #1, and application of nonfilled resin/NaF (4%) solution followed by exposure with the Holmium:YAG laser beam; Group #2, an application of an aqueous solution of NaF (4%) only; and Group #3, irradiation with the laser beam only. The teeth were exposed on the root surfaces with untreated control and experimental sites on opposite sides of the teeth. A 3 mm spot size covered an area of 3 X 5 mm with 0.450 (+/- .05) joules at a fluence of 2.66 - 3.3 J/cm2. All teeth were decalcified in a 10% Formic acid solution for a timed period. Samples were prepared for staining by sectioning the teeth at the dentoenamel junction and 3 mm apically to produce a cross-section of each tooth root surface. Each sample was placed in toluidine blue dye to observe the depth of dye penetration into the dentin of treated and control sites. Toluidine blue dye showed a consistent greater depth of dye penetration into the dentinal areas of the untreated control sites versus the resin/NaF-lased group. The topical fluoride only group did not appear different than the untreated control sites of the teeth. The lased only group showed areas of dye penetration similar to the untreated control sides with other areas of little or no dye penetration. The finding that HO:YAG laser energy/chemical agent produced increased resistance to demineralization of dentinal surfaces in vitro suggested potential clinical applications of this combined modality.

  15. Intracorporeal lithotripsy with the holmium:YAG laser

    NASA Astrophysics Data System (ADS)

    Denstedt, John D.; Razvi, Hassan A.; Chun, Samuel S.; Sales, Jack L.

    1995-05-01

    A variety of devices are currently available for intracorporeal stone fragmentation. Recently a new wavelength of laser, the Holmium:YAG, has demonstrated a variety of potential urologic applications including ablation of soft tissue lesions as well as stone fragmentation. This laser has a wavelength of 2100 nm and operates in a pulsed mode. Energy is delivered through a 400 um quartz end-firing fiber. In this presentation we review our clinical experience with the Holmium:YAG laser for the treatment of renal and ureteral calculi. Over a 23 month period, 63 patients underwent 67 procedures. Seven procedures consisted of percutaneous nephrolithotripsy for large or staghorn renal calculi. Sixty procedures were performed for ureteral stones. Procedures for proximal ureteral stones (6) employed a retrograde approach using flexible ureteroscopes (8.5 or 9.8). Stones in the mid ureter (12) and distal ureter (42) were approached transurethrally using a 6.9 rigid ureteroscope. Complete stone fragmentation without the need for additional procedures was achieved in 82% of cases. Treatment failures included 1 stone migration into the renal pelvis during laser activation, 6 patients who had incomplete fragmentation and 3 patients in which laser malfunction precluded complete fragmentation. Stone analysis available in 23 patients revealed calcium oxalate monohydrate (15), calcium oxalate dihydrate (2), cystine (2), uric acid (3) and calcium phosphate (1). A single complication of ureteral perforation occurred when the laser was fired without direct visual guidance. Radiographic follow-up at an average of 16 weeks is available in 22 patients and has identified 2 patients with ureteral strictures that are not believed to be related to laser lithotripsy. In summary, we have found the Holmium:YAG laser to be a reliable and versatile device for intracorporeal lithotripsy. Its safety and efficacy make it a suitable alternative for performing intracorporeal lithotripsy of urinary

  16. Urological applications of Ho/Nd:Yag laser

    NASA Astrophysics Data System (ADS)

    Grifoni, Riccardo; Pierangeli, Tiziana; Gioacchini, Andrea; Muraro, Giovanni B.

    2001-10-01

    The introduction of Ho:Yag laser has brought many advantages in urology. By this work we want show you our experience with this technology. Between April 1998 and May 2000 we treated 137 patients. Of these 28 had urinary lithiasis (18 bladder and 10 ureteral stones 3 in the upper, 2 in the middle and 5 in the distal tract), 40 were affected by enlargement of prostatic gland: 32 had B.P.H., 8 P.C.; 36 had T.C.C. and 33 strictures of urethra (27) or bladder neck (6). For ureteral lithiasis we used 200 micrometer fiber, energy of 0.5 - 1.4 J with 10 Hz of frequency. In case of bladder stones a 550 or 1000 micrometer using a power of 80 W. The prostatic gland were resected by a 550 micrometer fiber, 2.2 - 2.8 J, 25 - 30 Hz and 70 -80 W. The superficial bladder tumors were removed by 1.4 J with 10 - 15 Hz and 10 - 14 W. In the large tumors we completed the procedure by Nd:YAG at the base of the tumor. Urethra and bladder neck strictures were treated by 1.2 - 1.8 J and 10 - 30 Hz. We successful treated 26 patients with urinary lithiasis obtained the complete vaporization of the stones, 2 had endoscopic ancillary procedures. Out of 32 patients with B.P.H. 41% had the complete resection of the gland the others the resection of the 3d lobe. We removed 114 superficial bladder tumors and only 4 patients had a local recurrence. Of the patients with the strictures 4 had more than one treatment and about 87% had good result. From our experience the use of Holmium:Yag laser has been very efficacy to treat different urological diseases, also in patients with important comorbid disorders and its use reduce the stay in hospital and so the costs.

  17. Ignition of an automobile engine by high-peak power Nd:YAG/Cr⁴⁺:YAG laser-spark devices.

    PubMed

    Pavel, Nicolaie; Dascalu, Traian; Salamu, Gabriela; Dinca, Mihai; Boicea, Niculae; Birtas, Adrian

    2015-12-28

    Laser sparks that were built with high-peak power passively Q-switched Nd:YAG/Cr(4+):YAG lasers have been used to operate a Renault automobile engine. The design of such a laser spark igniter is discussed. The Nd:YAG/Cr(4+):YAG laser delivered pulses with energy of 4 mJ and 0.8-ns duration, corresponding to pulse peak power of 5 MW. The coefficients of variability of maximum pressure (COV(Pmax)) and of indicated mean effective pressure (COV(IMEP)) and specific emissions like hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NO(x)) and carbon dioxide (CO2) were measured at various engine speeds and high loads. Improved engine stability in terms of COV(Pmax) and COV(Pmax) and decreased emissions of CO and HC were obtained for the engine that was run by laser sparks in comparison with classical ignition by electrical spark plugs.

  18. Influence of the Ce:YAG Amount on Structure and Optical Properties of Ce:YAG-PMMA Composites for White LED

    NASA Astrophysics Data System (ADS)

    Armetta, Francesco; Sibeko, Motshabi A.; Luyt, Adriaan S.; Chillura Martino, Delia F.; Spinella, Alberto; Saladino, Maria Luisa

    2016-09-01

    Ce:YAG-poly(methyl methacrylate) (PMMA) composites were prepared by using a melt compounding method, adding several amounts of Ce:YAG in the range 0.1-5 wt. %. The optical properties of the obtained composites and of the composites combined with a blue LED were measured to investigate the effect of the amount of Ce:YAG on the resulting emitted light in view of possible application in white LED manufacture. An increase in Ce:YAG amount caused an increase in the emission and a shift of 15 nm, influencing the white LED performance. The structure and morphology of the composites were studied. The results show that the interaction between the two components, observed by using solid state NMR experiments, are the responsible for the observed shift.

  19. Iron-based amorphous alloys and methods of synthesizing iron-based amorphous alloys

    DOEpatents

    Saw, Cheng Kiong; Bauer, William A.; Choi, Jor-Shan; Day, Dan; Farmer, Joseph C.

    2016-05-03

    A method according to one embodiment includes combining an amorphous iron-based alloy and at least one metal selected from a group consisting of molybdenum, chromium, tungsten, boron, gadolinium, nickel phosphorous, yttrium, and alloys thereof to form a mixture, wherein the at least one metal is present in the mixture from about 5 atomic percent (at %) to about 55 at %; and ball milling the mixture at least until an amorphous alloy of the iron-based alloy and the at least one metal is formed. Several amorphous iron-based metal alloys are also presented, including corrosion-resistant amorphous iron-based metal alloys and radiation-shielding amorphous iron-based metal alloys.

  20. Possibilities of Nd: YAG laser utilization in medicine

    NASA Astrophysics Data System (ADS)

    Frank, Frank

    The thermic effect caused by the shrinkage and the drying of the tissues is used for cutting, denaturation, and coagulation of tissues with simultaneous filling of the blood and lymphatic vessels. The surgical Nd:YAG lasers, whose utilization is based on photothermic effects, have 120 W power and are used in neurosurgery, dermatology, gastroenterology, gynecology, urology, lung sickness, and jaw and vessel surgery. The treatment of tumors is particularly interesting because of the total destruction of the ill tissue, the homogeneity of the necrose and the obturation of the blood and lymphatic vessels. In all cases, the laser is a better solution for the patients and allows a shorter stay in hospital.

  1. Thulium YAG laser operation at 2.01 microns

    NASA Technical Reports Server (NTRS)

    Storm, Mark E.; Gettemy, Donald J.; Barnes, Norman P.; Cross, Patricia L.; Kokta, Milan R.

    1989-01-01

    Variable temperature laser experiments were performed with two compositions of Tm:Cr:YAG (5.0:1.0 and 1.5:2.0 percent substitutions), with special attention given to the spectroscopic details of energy transfer and quasi-3 level lasing. Differences in laser threshold and flashlamp degradation were found in lasing the two compositions, and it is suggested that the difference is due to the 1.5:2.0 rod having much less efficient energy transfer than the 5.0:1.0 Tm:Cr crystals. To first order, the thermal occupation factor is found to dominate laser threshold determination at temperatures betwen 120 and 240 K.

  2. Numerical control system of battery welding with pulsed YAG laser

    NASA Astrophysics Data System (ADS)

    Zhang, Guoshun; Yang, Zhaoxia; Zhang, Taishi; Wei, Zhigang; Li, Chaoyang

    1999-09-01

    This article briefly introduces the pulse YAG laser welding system, a new research achievement of my section. This system can weld the electric pole, the holly board and other aluminum parts of lithium battery, and the process of loading, unloading, compressing and welding can be completed automatically. Moreover, the software proprietary of the system is very good, and its interface is friendly too. In order to achieve optimum welding effect, we have designed special laser discharging waveform. Its rise delay time, fall delay time, and width are all designed specially. With this special technology, the welding spot we get is smooth like mirror, and the welding intensity can be controlled conveniently.

  3. Treatment of pulmonary diseases with Holmium:YAG laser

    NASA Astrophysics Data System (ADS)

    Zhang, Mei-Jue; Zhu, Jing; Zhang, Hui-Guo; Wang, Fu-Juan; Ke, Lin; Ma, Wei; Luo, Qun-Hua; Zhang, Yue-E.

    1998-11-01

    We report 5 cases of pulmonary disease treated with Holmium:YAG laser through fibrous bronchoscope. 1 inflammatory granuloma was cured after three times of treatment. Compared with conventional methods such as electrocautery and microwave treatment, laser has the merit of good hemostasis effect and quick recovery of the operation area. The other 4 patients who were suffered late lung cancer received 3-7 times of palliative treatment. After the treatment, the tumor tissues become smaller variably, and tact were unobstructed, symptoms of tract- obstructed obviously alleviated. We think that laser treatment has some practical significance in alleviating tract blocking of pulmonary diseases of late stage, and therefore raise the life quality.

  4. Dichroic mirror for high power Nd:YAG laser

    SciTech Connect

    Dinca, A.; Lupei, V.; Miclea, P.T.; Dinca, M.P.

    1996-12-31

    The paper presents the design of a dichroic mirror used in a Nd:YAG high power laser to reflect the 1.44 {micro}m radiation and to transmit the 1.064 {micro}m one. In order to obtain a wide transmission band, all the solutions for matching basic stack with the substrate, consisting in a number of periods less or equal than three, were investigated and the best was selected. The solutions were obtained by analytical inversion of the equations for the three layer equivalent system.

  5. Pulsed neodymium-YAG laser trabeculotomy: energy requirements and replicability.

    PubMed Central

    Dutton, G N; Allan, D; Cameron, S A

    1989-01-01

    Short pulsed laser trabeculotomy has been shown to reduce intraocular pressure in patients with primary open angle glaucoma. This study seeks to determine the energy levels required to produce a fistula into the canal of Schlemm for four different Q-switched neodymium-YAG lasers. The laser was fired at fixed human trabecular meshwork specimens at a range of energy settings for each laser and the characteristics and replicability of the lesions produced were analysed. Energy levels between 3 and 5 mJ were sufficient to produce fistulae into the canal of Schlemm with an approximately 50% success rate for each instrument. Images PMID:2706207

  6. Space qualified Nd:YAG laser (phase 1 - design)

    NASA Technical Reports Server (NTRS)

    Foster, J. D.; Kirk, R. F.

    1971-01-01

    Results of a design study and preliminary design of a space qualified Nd:YAG laser are presented. A theoretical model of the laser was developed to allow the evaluation of the effects of various parameters on its performance. Various pump lamps were evaluated and sum pumping was considered. Cooling requirements were examined and cooling methods such as radiation, cryogenic and conductive were analysed. Power outputs and efficiences of various configurations and the pump and laser lifetime are discussed. Also considered were modulation and modulating methods.

  7. Effect of transscleral neodymium: YAG cyclophotocoagulation on intraocular lenses

    SciTech Connect

    Blomquist, P.H.; Gross, R.L.; Koch, D.D. )

    1990-03-01

    A neodymium: YAG laser operating in the thermal mode was used to irradiate isolated intraocular lenses (IOLs) and to perform transscleral cyclophotocoagulation on pseudophakic autopsy eyes to investigate the potential damage to IOL haptics such irradiation may cause. In the isolated IOLs, 70 mJ of energy deformed and partially melted both polymethylmethacrylate (PMMA) and polypropylene haptics. One of the capsular-fixated PC-IOL haptics in an autopsy eye partially melted when irradiated with the maximum energy level (8.8 J), with the aiming beam focused 1 mm posterior to the limbus and maximal posterior focus offset.

  8. Nd:YAG holographic interferometer for aerodynamic research

    NASA Technical Reports Server (NTRS)

    Craig, J. E.; Lee, G.; Bachalo, W. D.

    1983-01-01

    A holographic interferometer system has been installed in the NASA Ames 2- by 2-Foot Transonic Wind Tunnel. The system incorporates a modern 10 pps, Nd:YAG pulsed laser which provides reliable operation and is easy to align. The spatial filtering requirements of the unstable resonator beam are described, as well as the integration of the system into the existing schlieren system. A two-plate holographic interferometer is used to reconstruct flow field data. For static wind tunnel models, the single exposure holograms are recorded in the usual manner; however, for dynamic models such as oscillating airfoils, synchronous laser hologram recording is used.

  9. Neodymium YAG laser for treatment of oral cavernous hemangiomas

    NASA Astrophysics Data System (ADS)

    Bradley, Paul F.

    1999-02-01

    Oral cavernous haemangiomas are common lesions which may require treatment due to episodes of bleeding when bitten or deformity particularly when involving the lips and/or cheeks. Surgery can be hazardous due to haemorrhage while cryosurgery tends to be tedious for large lesions and be accompanied by major oedema. Sclerosants produce hard bulky masses. Embolization is seldom helpful due to lack of arterial feeders. The Nd:YAG laser is proving a useful modality in the oro-facial region and appeared worth investigating for these lesions in a laboratory animal model, by thermography and in the clinical situation.

  10. 2.94 μm diode side pumped ErYAG laser

    NASA Astrophysics Data System (ADS)

    Xu, Zhi; Wang, Pengyuan; Liu, Wanfa; Li, Yimin; Gai, Baodong; Tan, Yannan; Jia, Chunyan; Guo, Jingwei

    2017-01-01

    We have demonstrated an average output power of 10 W quasi-continuous-wave mid-infrared laser at 2.94 μm from a diode laser (LD) side-pumped Er-doped yttrium aluminum garnet (YAG) crystal. The Er:YAG crystal was composed of Er-doped (50% doped) (YAG) bonded to undoped YAG. The LD was operated at a repetition rate of 150Hz and a pulse-width of 300 μs. The optical-optical conversion efficiency and the slope efficiency were 5.6% and 9.1%, respectively. The slope efficiency was not saturation yet, a higher output power can be expected with a higher LD pump power and colder temperature of the Er:YAG crystal.

  11. Analysis of the thermal effects in diode-pumped Tm:YAG ceramic slab lasers

    NASA Astrophysics Data System (ADS)

    Cheng, Xiaojin; Shang, Jianhua; Jiang, Benxue

    2017-03-01

    Tm:YAG ceramics with a quasi-three-level system are sensitive to temperature. The optical and thermodynamic properties of Tm:YAG ceramics can change with changing temperature, and this affects the output power stability and beam quality of lasers. Thus temperature control is a key and difficult problem for Tm:YAG lasers, especially for high power laser output. In combination with slab structure and grad-doping techniques for composite ceramics, the temperature distributions of Tm:YAG ceramics are analyzed. It is found that the temperature difference of a rationally designed grad-doping Tm:YAG ceramic can be reduced significantly with the same absorption pump power, which results in higher output power and beam quality.

  12. Laser-induced forward transfer technique for maskless patterning of amorphous V 2O 5 thin film

    NASA Astrophysics Data System (ADS)

    Chakraborty, S.; Sakata, H.; Yokoyama, E.; Wakaki, M.; Chakravorty, D.

    2007-11-01

    A laser-induced forward transfer technique has been applied for the maskless patterning of amorphous V 2O 5 thin films. A sheet beam of a frequency doubled (SHG) Q-switched Nd:YAG laser was irradiated on a transparent glass substrate (donor), the rear surface of which was pre-coated with a vacuum-deposited V 2O 5 180 nm thick film was either in direct contact with a second glass substrate (receiver) or a 0.14 mm air-gap was maintained between the donor film and the receiving substrate. Clear, regular stripe pattern of the laser-induced transferred film was obtained on the receiver. The pattern was characterized using X-ray diffraction (XRD), optical absorption spectroscopy, scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDAX), atomic force microscopy (AFM), etc.

  13. Effect of CO2, Nd:YAG and Er:YAG Lasers on Microtensile Bond Strength of Composite to Bleached-Enamel.

    PubMed

    Basir, Mahshid Mohammadi; Rezvani, Mohammad Bagher; Chiniforush, Nasim; Moradi, Zohreh

    2016-01-01

    Tooth restoration immediately after bleaching is challenging due to the potential problems in achieving adequate bond strength. The aim of this study was to evaluate the effect of surface treatment with ER:YAG, ND:YAG, CO2 lasers and 10% sodium ascorbate solution on immediate microtensile bond strength of composite resin to recently bleached enamel. Ninety sound molar teeth were randomly divided into three main groups (n:30) : NB (without bleaching), HB (bleached with 38% carbamide peroxide) and OB (bleached with Heydent bleaching gel assisted by diode laser). Each group was divided into five subgroups (n:6) : Si (without surface treatment), Er (Er:YAG laser), CO2 (CO2 laser), Nd (Nd:YAG laser) and As (Immersion in 10% sodium ascorbate solution). The bonding system was then applied and composite build-ups were constructed. The teeth were sectioned by low speed saw to obtain enamel- resin sticks and submitted to microtensile bond testing. Statistical analyses were done using two- way ANOVA, Tukey and Tamhane tests. µTBS of bleached teeth irradiated with ND:YAG laser was not significantly different from NB-Nd group. Microtensile bond strength of OB-Er group was higher than NB-Er and HB-Er groups. The mean µTBS of HB-CO2 group was higher than NB-CO2 group; the average µTBS of HB-As and OB-As groups was also higher than NB-As group. Use of Nd:YAG, CO2 lasers and 10% sodium ascorbate solution could improve the bond strength in home-bleached specimens. Application of ND:YAG laser on nonbleached specimens and Er:YAG laser on office-bleached specimens led to the highest µTBS in comparison to other surface treatments in each main group.

  14. Ablative fractionated erbium:YAG laser for the treatment of ice pick alar scars due to neodymium:YAG laser burns.

    PubMed

    Cohen, Joel L; Babcock, Michael J

    2009-01-01

    The authors present a case of ice pick scars forming in the nasal alar grooves of a patient who was treated with a 1064-nm neodymium:yttrium-aluminum-garnet (Nd:YAG) laser for facial telangiectasias. Treatment options for these types of scars are reviewed and specifically we report the success of an ablative fractionated 2940-nm erbium:yttrium-aluminum-garnet (Er:YAG) laser.

  15. Effect of CO2, Nd:YAG and Er:YAG Lasers on Microtensile Bond Strength of Composite to Bleached-Enamel

    PubMed Central

    Basir, Mahshid Mohammadi; Rezvani, Mohammad Bagher; Chiniforush, Nasim; Moradi, Zohreh

    2016-01-01

    Background: Tooth restoration immediately after bleaching is challenging due to the potential problems in achieving adequate bond strength. Objective: The aim of this study was to evaluate the effect of surface treatment with ER:YAG, ND:YAG, CO2 lasers and 10% sodium ascorbate solution on immediate microtensile bond strength of composite resin to recently bleached enamel. Materials & Methods: Ninety sound molar teeth were randomly divided into three main groups (n:30) : NB (without bleaching), HB (bleached with 38% carbamide peroxide) and OB (bleached with Heydent bleaching gel assisted by diode laser). Each group was divided into five subgroups (n:6) : Si (without surface treatment), Er (Er:YAG laser), CO2 (CO2 laser), Nd (Nd:YAG laser) and As (Immersion in 10% sodium ascorbate solution). The bonding system was then applied and composite build-ups were constructed. The teeth were sectioned by low speed saw to obtain enamel- resin sticks and submitted to microtensile bond testing. Statistical analyses were done using two- way ANOVA, Tukey and Tamhane tests. Results: µTBS of bleached teeth irradiated with ND:YAG laser was not significantly different from NB-Nd group. Microtensile bond strength of OB-Er group was higher than NB-Er and HB-Er groups. The mean µTBS of HB-CO2 group was higher than NB-CO2 group; the average µTBS of HB-As and OB-As groups was also higher than NB-As group. Conclusion: Use of Nd:YAG, CO2 lasers and 10% sodium ascorbate solution could improve the bond strength in home-bleached specimens. Application of ND:YAG laser on nonbleached specimens and Er:YAG laser on office-bleached specimens led to the highest µTBS in comparison to other surface treatments in each main group. PMID:27385998

  16. Healing of rat mouth mucosa after irradiation with CO2, Nd:YAG, and CO2-Nd:YAG combination lasers.

    PubMed

    Luomanen, M; Rauhamaa-Mäkinen, R; Meurman, J H; Kosloff, T; Tiitta, O

    1994-08-01

    The healing process of wounds made by a combination laser was studied in 90 rats. The laser system enabled both separate and combined use of CO2 and Nd:YAG laser irradiations. The laser wounds and the control excision wounds made by alligator forceps appeared on both sides of the tongue. Specimens from the wound sites were taken immediately, 6 h, and 1, 2, 4, 7, 11, 21, 28, and 42 days after surgery. The wound-healing process was studied by macroscopic evaluation before preparing the specimens for light microscopy. Some differences were noted in the wound-healing process among the three groups into which the experimental animals were divided. Tissue coagulation damage was most extensive in the Nd:YAG laser sites, where it was observed in its full extent 4 days after surgery. Epithelial cells were seen to begin to proliferate in all the wounds 6 h after surgery. Re-epithelialization was completed by between 7 (CO2) and 21 days (Nd:YAG) at all the wound sites. The inflammatory cell infiltration was more prominent in the Nd:YAG and the CO2-Nd:YAG combination laser wounds than in the CO2 and excision wounds during healing. Tissue regeneration occurred faster with less contraction in the combination CO2-Nd:YAG wounds than in Nd:YAG wounds. The best macroscopic healing result was seen in the CO2 wound sites. The combination laser was effective both at cutting and at coagulating tissue. Combining the CO2 and Nd:YAG laser irradiation into one beam resulted in a greater incision depth than what could have been expected from using the two lasers separately.

  17. Amorphous Silicon Based Neutron Detector

    SciTech Connect

    Xu, Liwei

    2004-12-12

    Various large-scale neutron sources already build or to be constructed, are important for materials research and life science research. For all these neutron sources, neutron detectors are very important aspect. However, there is a lack of a high-performance and low-cost neutron beam monitor that provides time and temporal resolution. The objective of this SBIR Phase I research, collaboratively performed by Midwest Optoelectronics, LLC (MWOE), the University of Toledo (UT) and Oak Ridge National Laboratory (ORNL), is to demonstrate the feasibility for amorphous silicon based neutron beam monitors that are pixilated, reliable, durable, fully packaged, and fabricated with high yield using low-cost method. During the Phase I effort, work as been focused in the following areas: 1) Deposition of high quality, low-defect-density, low-stress a-Si films using very high frequency plasma enhanced chemical vapor deposition (VHF PECVD) at high deposition rate and with low device shunting; 2) Fabrication of Si/SiO2/metal/p/i/n/metal/n/i/p/metal/SiO2/ device for the detection of alpha particles which are daughter particles of neutrons through appropriate nuclear reactions; and 3) Testing of various devices fabricated for alpha and neutron detection; As the main results: · High quality, low-defect-density, low-stress a-Si films have been successfully deposited using VHF PECVD on various low-cost substrates; · Various single-junction and double junction detector devices have been fabricated; · The detector devices fabricated have been systematically tested and analyzed. · Some of the fabricated devices are found to successfully detect alpha particles. Further research is required to bring this Phase I work beyond the feasibility demonstration toward the final prototype devices. The success of this project will lead to a high-performance, low-cost, X-Y pixilated neutron beam monitor that could be used in all of the neutron facilities worldwide. In addition, the technologies

  18. Novel Internal Friction of Amorphous Solids

    NASA Astrophysics Data System (ADS)

    Liu, Xiao

    1998-03-01

    Owing to the great sensitivity of the double-paddle oscillators, we have recently measured the low-temperature internal friction of amorphous silicon films (X. Liu, B. E. White, Jr., R. O. Pohl, E. Iwanizcko, K. M. Jones, A. H. Mahan, B. N. Nelson, R. S. Crandall, S. Veprek, Phys. Rev. Lett. 78), 4418 (1997). While e-beam evaporation, sputtering, or Si^+ ion implantation produce a-Si films with similar tunneling states as in all amorphous solids, hydrogenated a-Si films with 1 at.% H prepared by hot-wire chemical vapor deposition show no sign of any significant low energy excitations. This observation offers an exciting opportunity to study the structural origin of the low energy excitations common to amorphous solids. A possible explanation is that in the hydrogenated films the amorphous structure is closer to the fourfold coordinated continuous random network expected in amorphous Si, and thus the lattice is more constrained, resulting in the absence of tunneling states.

  19. SURVIVAL OF AMORPHOUS WATER ICE ON CENTAURS

    SciTech Connect

    Guilbert-Lepoutre, Aurelie

    2012-10-01

    Centaurs are believed to be Kuiper Belt objects in transition between Jupiter and Neptune before possibly becoming Jupiter family comets. Some indirect observational evidence is consistent with the presence of amorphous water ice in Centaurs. Some of them also display a cometary activity, probably triggered by the crystallization of the amorphous water ice, as suggested by Jewitt and this work. Indeed, we investigate the survival of amorphous water ice against crystallization, using a fully three-dimensional thermal evolution model. Simulations are performed for varying heliocentric distances and obliquities. They suggest that crystallization can be triggered as far as 16 AU, though amorphous ice can survive beyond 10 AU. The phase transition is an efficient source of outgassing up to 10-12 AU, which is broadly consistent with the observations of the active Centaurs. The most extreme case is 167P/CINEOS, which barely crystallizes in our simulations. However, amorphous ice can be preserved inside Centaurs in many heliocentric distance-obliquity combinations, below a {approx}5-10 m crystallized crust. We also find that outgassing due to crystallization cannot be sustained for a time longer than 10{sup 4}-10{sup 4} years, leading to the hypothesis that active Centaurs might have recently suffered from orbital changes. This could be supported by both observations (although limited) and dynamical studies.

  20. Amorphous silicon detectors in positron emission tomography

    SciTech Connect

    Conti, M. Lawrence Berkeley Lab., CA ); Perez-Mendez, V. )

    1989-12-01

    The physics of the detection process is studied and the performances of different Positron Emission Tomography (PET) system are evaluated by theoretical calculation and/or Monte Carlo Simulation (using the EGS code) in this paper, whose table of contents can be summarized as follows: a brief introduction to amorphous silicon detectors and some useful equation is presented; a Tantalum/Amorphous Silicon PET project is studied and the efficiency of the systems is studied by Monte Carlo Simulation; two similar CsI/Amorphous Silicon PET projects are presented and their efficiency and spatial resolution are studied by Monte Carlo Simulation, light yield and time characteristics of the scintillation light are discussed for different scintillators; some experimental result on light yield measurements are presented; a Xenon/Amorphous Silicon PET is presented, the physical mechanism of scintillation in Xenon is explained, a theoretical estimation of total light yield in Xenon and the resulting efficiency is discussed altogether with some consideration of the time resolution of the system; the amorphous silicon integrated electronics is presented, total noise and time resolution are evaluated in each of our applications; the merit parameters {epsilon}{sup 2}{tau}'s are evaluated and compared with other PET systems and conclusions are drawn; and a complete reference list for Xenon scintillation light physics and its applications is presented altogether with the listing of the developed simulation programs.

  1. Er:YAG and CTH:YAG laser radiation: contact versus non-contact enamel ablation and sonic-activated bulk composite placement

    NASA Astrophysics Data System (ADS)

    Buckova, M.; Kasparova, M.; Dostalova, T.; Jelinkova, H.; Sulc, J.; Nemec, M.; Fibrich, M.; Bradna, P.; Miyagi, M.

    2013-05-01

    Laser radiation can be used for effective caries removal and cavity preparation without significant thermal effects, collateral damage of tooth structure, or patient discomfort. The aim of this study was to compare the quality of tissue after contact or non-contact Er:YAG and CTH:YAG laser radiation ablation. The second goal was to increase the sealing ability of hard dental tissues using sonic-activated bulk filling material with change in viscosity during processing. The artificial caries was prepared in intact teeth to simulate a demineralized surface and then the Er:YAG or CTH:YAG laser radiation was applied. The enamel artificial caries was gently removed by the laser radiation and sonic-activated composite fillings were inserted. A stereomicroscope and then a scanning electron microscope were used to evaluate the enamel surface. Er:YAG contact mode ablation in enamel was quick and precise; the cavity was smooth with a keyhole shaped prism and rod relief arrangement without a smear layer. The sonic-activated filling material was consistently regularly distributed; no cracks or microleakage in the enamel were observed. CTH:YAG irradiation was able to clean but not ablate the enamel surface; in contact and also in non-contact mode there was evidence of melting and fusing of the enamel.

  2. [Morphologic evaluation of the bonding between adhesive/composite resin and dentin irradiated with Er:YAG and Nd:YAG lasers: comparative study using scanning microscopy].

    PubMed

    Oda, M; Oliveira, D C; Liberti, E A

    2001-01-01

    Since bonding systems were introduced in the restorative procedures carried out with esthetic materials, the treatment of dentin surfaces has been widely studied in order to establish the ideal technique. The application of 37% phosphoric acid on dentin is still the best known method. However, alternative methods for treating the dentin surface have been discussed in the literature, including the utilization of some kinds of laser irradiation. The purpose of this research was to morphologically evaluate the bond between adhesive materials and the dentin treated with Er:YAG and Nd:YAG lasers, in a comparative study by means of scanning electron microscopy (SEM). Irradiation either substituted acid etching, or was associated to it. Recently extracted bovine incisors were utilized. They received class V cavity preparations and were restored with a bonding system and a light-cured composite resin. Meanwhile, some of the teeth underwent irradiation with Er:YAG laser or Nd:YAG laser before the application of the bonding agent and the composite resin. The samples were selected, prepared for SEM and submitted to morphological analysis. Data were registered in photomicrographs. Based on the microscopic observations, we concluded that only in the dentin surfaces submitted to irradiation with Er:YAG laser and to acid conditioning there was penetration of resin into the dentine. With the Nd:YAG laser treatment, there was only visual superposition of resin over the dentin surface, which suggests that there was only occlusion of the tubules, with characteristics of fusion in the superficial dentine.

  3. Clinical comparison of potassium-titanyl-phosphate (KTP) versus neodymium:YAG (Nd:YAG) laser treatment for lower extremity telangiectases.

    PubMed

    Ozden, Müge Güler; Bahçivan, Muzaffer; Aydin, Fatma; Şentürk, Nilgün; Bek, Yüksel; Cantürk, Tayyar; Turanli, Ahmet Yaşar

    2011-06-01

    The Nd:YAG laser has been considered the gold standard of treatment for leg veins, but pain and side effects have fueled physicians to use treatment alternatives. To compare the clinical efficacy of the long-pulsed 1064-nm Nd:YAG laser with KTP laser irradiation in the treatment of leg telangiectasia. A series of 16 patients with size-matched superficial telangiectases of the lower extremities were randomly assigned to receive three consecutive monthly treatments with the long-pulsed 1064-nm Nd:YAG on one leg and 532-nm KTP laser irradiation on the other. For the 16 patients who completed the study, 64 leg vein sites were treated. Average clinical improvement scores were 1.94 and 1.25 for the KTP laser-treated leg and 3.38 and 3.50 for the Nd:YAG laser-treated leg with thin (≤ 1 mm) and large (1-3 mm) vessels, respectively. After the third treatment session, average improvement scores of 2.44, 1.31 and 3.75, 3.23 were given for the KTP and Nd:YAG laser-treated sides, respectively. Both the 1064-nm Nd:YAG and KTP lasers are effective in the treatment of lower extremity telangiectases. However, the KTP laser has very low efficacy with vessels larger than 1 mm and should not be elected when treating such vessels.

  4. Comparison of effectiveness of 1,064-nm Nd:YAG laser and Nd:YAG laser-IPL combination treatments in hand skin rejuvenation.

    PubMed

    Oktem, Ayse; Kocyigit, Pelin

    2016-10-01

    Evaluation of the efficacy and side effects of neodymium-doped yttrium aluminum garnet (Nd:YAG) laser and Nd:YAG laser-intense pulsed light (IPL) combination treatments in photorejuvenations of skin of the hand, and determining their impacts on patient satisfaction. Thirty-five female patients with signs of photoaging on the skin of their hands were included in the study. Three sessions of IPL and four sessions of Nd:YAG laser treatment were applied to the right hand in total with 2-week intervals between each session, whereas six sessions of Nd:YAG laser treatment were applied to the left hand of patients with 2-week intervals between each session. The patients' ages ranged between 31 and 78, and mean age was 60.77 ± 9.48. While there was no difference in pigment distribution, fine wrinkles, coarse wrinkles, and global scores between the right and left hand prior to treatment (p > 0.05), average pigment tone score was higher in the right hand with a statistically significant difference (p < 0.05). There was greater improvement in scores of pigment distribution, fine wrinkles, sallowness, pigment tone parameters, and global score on the right hand compared to left hand, which was statistically significant (p <0.001). In rejuvenation of photoaged dorsal skin of the hand, IPL-Nd:YAG laser combination treatment surpasses Nd:YAG laser treatment.

  5. V:YAG saturable absorber for flash-lamp and diode-pumped solid state lasers

    NASA Astrophysics Data System (ADS)

    Sulc, Jan; Jelinkova, Helena; Nemec, Michal; Nejezchleb, Karel; Skoda, Vaclav

    2004-09-01

    V:YAG saturable absorber was used for efficient Q-switching and mode-locking of Nd:YAG and Nd:YAP flash-lamp or diode pumped lasers operating in 1.3 mm region. Crystals of Yttrium-Aluminum Garnet (YAG) doped with three-valence vanadium V3+ in tetrahedral position (V:YAG) were grown using of Czochralski method in reducing protective atmosphere. High purity oxides were used for crystal growth (Y2O3 (5N), Al2O3 (5N), V2O5 (4N)). Concentration of V2O5 in the melt reached up to 1 wt. %. Discs of the diameter 5 or 10 mm and of various thickness were machined from grown V:YAG crystals. The discs were both sides polished and AR coated so that minimum reflectivity at 1.08 and 1.34 microns was reached. The initial transmission of the saturable absorber was dependent on the sample's thickness and its annealing process. We report stability improvement of passively mode-locked (by these V:YAG crystals) Nd:YAP flash-lamp pumped lasers. The maximum output energy 53 mJ at wavelength 1340 nm was obtained for Nd:YAP flash-lamp pumped laser operating at repetition rate 5 Hz. Mode-locked train envelope width was measured to be 22 ns (FWHM). Individual pulses inside the train were shorter than 1 ns. Also results with composite Nd:YAG rod Q-switched by V:YAG crystal and with Nd:YAG/V:YAG monolith rod under CW longitudinal diode pumping was obtained and compared. These laser systems represent new powerfull sources in the near infrared region.

  6. Phase transitions in biogenic amorphous calcium carbonate

    PubMed Central

    Gong, Yutao U. T.; Killian, Christopher E.; Olson, Ian C.; Appathurai, Narayana P.; Amasino, Audra L.; Martin, Michael C.; Holt, Liam J.; Wilt, Fred H.; Gilbert, P. U. P. A.

    2012-01-01

    Crystalline biominerals do not resemble faceted crystals. Current explanations for this property involve formation via amorphous phases. Using X-ray absorption near-edge structure (XANES) spectroscopy and photoelectron emission microscopy (PEEM), here we examine forming spicules in embryos of Strongylocentrotus purpuratus sea urchins, and observe a sequence of three mineral phases: hydrated amorphous calcium carbonate (ACC·H2O) → dehydrated amorphous calcium carbonate (ACC) → calcite. Unexpectedly, we find ACC·H2O-rich nanoparticles that persist after the surrounding mineral has dehydrated and crystallized. Protein matrix components occluded within the mineral must inhibit ACC·H2O dehydration. We devised an in vitro, also using XANES-PEEM, assay to identify spicule proteins that may play a role in stabilizing various mineral phases, and found that the most abundant occluded matrix protein in the sea urchin spicules, SM50, stabilizes ACC·H2O in vitro. PMID:22492931

  7. IUE observations of amorphous hot galaxies

    NASA Technical Reports Server (NTRS)

    Lamb, S. A.; Hjellming, M. S.; Gallagher, J. S., III; Hunter, D. A.

    1985-01-01

    Blue amorphous galaxies are star-forming, irregularlike systems which lack the spatially distinct OB stellar groups that are characteristic of most late-type galaxies. In order to better understand the nature of star-formation processes in these unusual galaxies, short-wavelength IUE spectra of the amorphous galaxies NGC 1705 and NGC 1800 have been obtained. It is found that NGC 1705 contains a normal mix of OB stars, which is consistent with the nearly constant recent star-formation rate inferred from new optical data. NGC 1800 is likely to have similar properties, and blue galaxies with amorphous structures thus do not show evidence for anomalies in stellar populations. The UV spectra of these galaxies and a variety of other hot extragalactic stellar systems in fact have similar characteristics, which suggests OB stellar populations are often homogeneous in their properties.

  8. Investigation of superconducting interactions and amorphous semiconductors

    NASA Technical Reports Server (NTRS)

    Janocko, M. A.; Jones, C. K.; Gavaler, J. R.; Deis, D. W.; Ashkin, M.; Mathur, M. P.; Bauerle, J. E.

    1972-01-01

    Research papers on superconducting interactions and properties and on amorphous materials are presented. The search for new superconductors with improved properties was largely concentrated on the study of properties of thin films. An experimental investigation of interaction mechanisms revealed no new superconductivity mechanism. The properties of high transition temperature, type 2 materials prepared in thin film form were studied. A pulsed field solenoid capable of providing fields in excess of 300 k0e was developed. Preliminary X-ray measurements were made of V3Si to determine the behavior of cell constant deformation versus pressure up to 98 kilobars. The electrical properties of amorphous semiconducting materials and bulk and thin film devices, and of amorphous magnetic materials were investigated for developing radiation hard, inexpensive switches and memory elements.

  9. Amorphous metallic films in silicon metallization systems

    NASA Astrophysics Data System (ADS)

    So, F.; Kolawa, E.; Nicolet, M. A.

    1985-06-01

    Diffusion barrier research was focussed on lowering the chemical reactivity of amorphous thin films on silicon. An additional area of concern is the reaction with metal overlays such as aluminum, silver, and gold. Gold was included to allow for technology transfer to gallium arsenide PV cells. Amorphous tungsten nitride films have shown much promise. Stability to annealing temperatures of 700, 800, and 550 C were achieved for overlays of silver, gold, and aluminum, respectively. The lower results for aluminum were not surprising because there is an eutectic that can form at a lower temperature. It seems that titanium and zirconium will remove the nitrogen from a tungsten nitride amorphous film and render it unstable. Other variables of research interest were substrate bias and base pressure during sputtering.

  10. Nanocrystalline silicon/amorphous silicon dioxide superlattices

    SciTech Connect

    Fauchet, P.M.; Tsybeskov, L.; Zacharias, M. |; Hirschman, K. |

    1998-12-31

    Thin layers made of densely packed silicon nanocrystals sandwiched between amorphous silicon dioxide layers have been manufactured and characterized. An amorphous silicon/amorphous silicon dioxide superlattice is first grown by CVD or RF sputtering. The a-Si layers are recrystallized in a two-step procedure (nucleation + growth) for form layers of nearly identical nanocrystals whose diameter is given by the initial a-Si layer thickness. The recrystallization is monitored using a variety of techniques, including TEM, X-Ray, Raman, and luminescence spectroscopies. When the a-Si layer thickness decreases (from 25 nm to 2.5 nm) or the a-SiO{sub 2} layer thickness increases (from 1.5 nm to 6 nm), the recrystallization temperature increases dramatically compared to that of a single a-Si film. The removal of the a-Si tissue present between the nanocrystals, the passivation of the nanocrystals, and their doping are discussed.

  11. Amorphous metallic films in silicon metallization systems

    NASA Technical Reports Server (NTRS)

    So, F.; Kolawa, E.; Nicolet, M. A.

    1985-01-01

    Diffusion barrier research was focussed on lowering the chemical reactivity of amorphous thin films on silicon. An additional area of concern is the reaction with metal overlays such as aluminum, silver, and gold. Gold was included to allow for technology transfer to gallium arsenide PV cells. Amorphous tungsten nitride films have shown much promise. Stability to annealing temperatures of 700, 800, and 550 C were achieved for overlays of silver, gold, and aluminum, respectively. The lower results for aluminum were not surprising because there is an eutectic that can form at a lower temperature. It seems that titanium and zirconium will remove the nitrogen from a tungsten nitride amorphous film and render it unstable. Other variables of research interest were substrate bias and base pressure during sputtering.

  12. Amorphous/epitaxial superlattice for thermoelectric application

    NASA Astrophysics Data System (ADS)

    Ishida, Akihiro; Thao, Hoang Thi Xuan; Shibata, Mamoru; Nakashima, Seisuke; Tatsuoka, Hirokazu; Yamamoto, Hidenari; Kinoshita, Yohei; Ishikiriyama, Mamoru; Nakamura, Yoshiaki

    2016-08-01

    An amorphous/epitaxial superlattice system is proposed for application to thermoelectric devices, and the superlattice based on a PbGeTeS system was prepared by the alternate deposition of PbS and GeTe using a hot wall epitaxy technique. The structure was analyzed by high-resolution transmission electron microscopy (HRTEM) and X-ray analysis, and it was found that the superlattice consists of an epitaxial PbTe-based layer and a GeS-based amorphous layer by the reconstruction of the constituents. A reduction in thermal conductivity due to the amorphous/epitaxial system was confirmed by a 2ω method. Electrical and thermoelectric properties were measured for the samples.

  13. Transparency and microstructure of YAG:Ce phosphor particles

    NASA Astrophysics Data System (ADS)

    Kuznetsova, D. E.; Dosovitskiy, G. A.; Dosovitskiy, A. E.

    2017-04-01

    Influence of microstructure of YAG:Ce powder particles on their optical properties is studied to estimate light extraction efficiency from them. YAG:Ce powders are obtained using co-precipitation method and subsequent heat treatment. Single-phase garnet powder is obtained after heating to 1000 °C and higher. Microstructure changes significantly with increase of heat treatment temperature: after heat treatment at 900 °C powder comprises pieces of xerogel consisting of 20 nm particles and transparent in transmitted light under the optical microscope; after a heat treatment at 1300 °C well defined grains and pores are formed in powder particles, which is accompanied by a significant decrease of optical transparency. Photoluminescence intensity increases most significantly up to heat treatment temperature of 1300 °C, further increase of temperature leads to increase of photoluminescence intensity by less than 10%. It is supposed that development of pores in the particles obtained after thermal treatment above 1300 °C diminishes light extraction.

  14. Dynamics of pulsed holmium:YAG laser photocoagulation of albumen

    NASA Astrophysics Data System (ADS)

    Pfefer, T. Joshua; Foong Chan, Kin; Hammer, Daniel X.; Welch, A. J.

    2000-05-01

    The pulsed holmium:YAG laser (λ = 2.12 µm, τp = 250 µs) has been investigated as a method for inducing localized coagulation for medical procedures, yet the dynamics of this process are not well understood. In this study, photocoagulation of albumen (egg white) was analysed experimentally and results compared with optical-thermal simulations to investigate a rate process approach to thermal damage and the role of heat conduction and dynamic changes in absorption. The coagulation threshold was determined using probit analysis, and coagulum dynamics were documented with fast flash photography. The nonlinear computational model, which included a Beer's law optical component, a finite difference heat transfer component and an Arrhenius equation-based damage calculation, was verified against data from the literature. Moderate discrepancies between simulation results and our experimental data probably resulted from the use of a laser beam with an irregular spatial profile. This profile produced a lower than expected coagulation threshold and an irregular damage distribution within a millisecond after laser onset. After 1 ms, heat conduction led to smoothing of the coagulum. Simulations indicated that dynamic changes in absorption led to a reduction in surface temperatures. The Arrhenius equation was shown to be effective for simulating transient albumen coagulation during pulsed holmium:YAG laser irradiation. Greater understanding of pulsed laser-tissue interactions may lead to improved treatment outcome and optimization of laser parameters for a variety of medical procedures.

  15. Holmium:YAG laser angioplasty: treatment of acute myocardial infarction

    NASA Astrophysics Data System (ADS)

    Topaz, On

    1993-06-01

    We report our clinical experience with a group of 14 patients who presented with acute myocardial infarction. A holmium:YAG laser was applied to the infarct-related artery. This laser emits 250 - 600 mJ per pulse, with a pulse length of 250 microseconds and repetition rate of 5 Hz. Potential benefits of acute thrombolysis by lasers include the absence of systemic lytic state; a shortened thrombus clearing time relative to using thrombolytics; safe removal of the intracoronary thrombus and facilitation of adjunct balloon angioplasty. Potential clinical difficulties include targeting the obstructive clot and plaque, creation of debris and distal emboli and laser-tissue damage. It is conceivable that holmium:YAG laser can be a successful thrombolytic device as its wave length (2.1 microns) coincides with strong water absorption peaks. Since it is common to find an atherosclerotic plaque located under or distal to the thrombotic occlusion, this laser can also be applied for plaque ablation, and the patient presenting with acute myocardial infarction can clearly benefit from the combined function of this laser system.

  16. Containment-enhanced Ho:YAG photofragmentation of soft tissues

    NASA Astrophysics Data System (ADS)

    Christens-Barry, William A.; Guarnieri, Michael; Carson, Benjamin S.

    1998-01-01

    Laser surgery of soft tissue can exploit the power of brief, intense pulses of light to cause localized disruption of tissue with minimal effect upon surrounding tissue. In particular, studies of Ho:YAG laser surgery have shown that the effects of cavitation upon tissues and bone depend upon the physical composition of structures in the vicinity of the surgical site. For photofragmentation of occluding structures within catheters and other implant devices, it is possible to exploit the particular geometry of the catheter to amplify the effects of photofragmentation beyond those seen in bulk tissue. A Ho:YAG laser was used to photofragment occlusive material (tissue and tissue analogs) contained in glass capillary tubing and catheter tubing of the kind used in ventricular shunt implants for the management of hydrocephalus. Occluded catheters obtained from patient explants were also employed. Selection of operational parameters used in photoablation and photofragmentation of soft tissue must consider the physical composition and geometry of the treatment site. In the present case, containment of the soft tissue within relatively inelastic catheters dramatically alters the extent of photofragmentation relative to bulk (unconstrained) material. Our results indicate that the disruptive effect of cavitation bubbles is increased in catheters, due to the rapid displacement of material by cavitation bubbles comparable in size to the inner diameter of the catheter. The cylindrical geometry of the catheter lumen may additionally influence the propagation of acoustic shock waves that result from the collapse of the condensing cavitation bubbles.

  17. Hollow waveguide for giant Er:YAG laser pulses transfer

    NASA Astrophysics Data System (ADS)

    Nemec, Michal; Jelinkova, Helena; Koranda, Petr; Cech, Miroslav; Sulc, Jan; Miyagi, Mitsunobu; Shi, Yi-Wei; Matsuura, Yuji

    2004-06-01

    Short Er:YAG laser pulses were delivered by a cyclic olefin polymer coated silver hollow glass (COP/Ag) waveguide specially designed for a high power radiation. Er:YAG laser was Q-switched by an electro-optic shutter - LiNbO3 Pockels cell with Brewster angle cut input/output faces. The maximum energy output obtained from this system was 29 mJ with the length of pulse 69 ns corresponding to 420 kW output peak power. The system was working with the repetition rate of 1.5 Hz. A delivery system composed of a lens (f = 40 mm), protector and waveguide with the 700/850 μm diameter and 50 cm or 1 m length. The measured maximum delivered intensity was 86 MW/cm2 what corresponds to the transmission of 78.6 % for whole delivery system. Using of a sealed cap, this delivery system gives a possibility of the contact surgical treatment in many medicine branches, for example ophthalmology, urology or dentistry.

  18. Dentin adhesive tensile strength after Nd:YAG laser application

    NASA Astrophysics Data System (ADS)

    Lizarelli, Rosane F. Z.; Miranda, Walter G., Jr.; Eduardo, Carlos d. P.

    1999-05-01

    The authors evaluated, in vitro, the tensile strength of a hydrophilic adhesive on dentin surface, with and without previous treatment with high power Nd:YAG laser. Power of 1.0 W and 2.0 W with respective frequencies of 25 Hz and 50 Hz were used. Thirteen human extracted molars were prepared and randomly separated in five groups: GI, Nd:YAG laser with 1.0 W plus SBMPP (3M) adhesive system; GII, laser with 2.0 W, plus adhesive system; GIII, laser with 1.0 W; GIV, laser with 2.0 W; GV, adhesive system to treat dentin surface. To each group five samples with a composite bottom each, totalling in 25 samples, which were kept in distilled water, by 37°C, during 30 days. After that, thermal cycling was applied. After this period, the samples were submitted the tensile strength test to evaluate the necessary threshold of power to break up the adhesive bond of composite button from dentin surface. The statistical evaluation was done through variance analysis. Results showed that the values of tensile strength of the GV (26.4 kgf/cm2) were better than GI (4.6 kgf/cm2) which was the best laser group: GIII (2.4 kgf/cm2); GII (1.7 kgf/cm2) and GIV (1.2 kgf/cm2).

  19. Intrinsic reduction of the depolarization in Nd:YAG crystals.

    PubMed

    Puncken, Oliver; Tünnermann, Henrik; Morehead, James J; Wessels, Peter; Frede, Maik; Neumann, Jörg; Kracht, Dietmar

    2010-09-13

    The output power of linearly polarized Nd:YAG lasers is typically limited by thermally induced birefringence, which causes depolarization. However, this effect can be reduced either by use of some kind of depolarization compensation or by use of crystals which are cut in [110]- and [100]-direction, instead of the common [111]-direction. Investigations of the intrinsic reduction of the depolarization by use of these crystals are presented. To our knowledge, this is the first probe beam-experiment describing a comparison between [100]-, [110]- and [111]-cut Nd:YAG crystals in a pump power regime between 100 and 200 W. It is demonstrated that the depolarization can be reduced by a factor of 6 in [100]-cut crystals. The simulations reveal that a reduction of depolarization by use of a [110]-cut crystal in comparison with a [100]-cut crystal only becomes possible at pump powers in the kW region. Analysis also shows that the bifocusing for [100]-cut is slightly smaller and more asymmetrical than for [111]-cut.

  20. Nd:YAG laser in the treatment of colorectal cancer

    NASA Astrophysics Data System (ADS)

    Horak, Ladislav; Dvorak, K.; Fanta, J.

    1996-01-01

    Nd:YAG laser has been used in the treatment of colorectal cancer since the 80s. Since January of 1988 our clinic uses laser in therapeutic program. In clinical treatments laser with the wavelength of 1064 micrometer and power of 40 - 50 W is used. Only in rare cases do we use power over 50 W. the ratio of energy for one treatment depends only on clinical effect, there are no other limits. In the first period of our clinical practice, from 1988 to 1991, all the laser treatments were held under short-term anesthesia. Our patients were hospitalized for 2 or 3 days. For the actual treatments, we used the rigid endoscopic technique and also the flexible technique (coloscop). We preferred the flexible technique definitely. Since January of 1991 we practice almost all treatments in ambulant schedule without general anesthesia. Only in the cases where treatments reach under linea dentata, we choose short-term inhale anesthesia. The patients are hospitalized for one day. In the actual treatments we take advantage of Nd:YAG laser. We try to vaporize most of the tumor masses during great hemostasis. The hemostasis is defined by the zone of coagulation.

  1. YAG(Ce) crystal characterization with proton beams

    NASA Astrophysics Data System (ADS)

    Sipala, V.; Randazzo, N.; Aiello, S.; Leonora, E.; Lo Presti, D.; Russo, M.; Stancampiano, C.; Cirrone, G. A. P.; Cuttone, G.; Romano, F.; Civinini, C.; Scaringella, M.; Bashkirov, V. A.; Schulte, R. W.

    2011-10-01

    A YAG(Ce) crystal has been characterized with a proton beam up to 100 MeV. Tests were performed to investigate the possibility of using this detector as a proton calorimeter. A crystal size has been chosen that is able to stop up to 200 MeV. Energy resolution and light response have been measured at Laboratori Nazionali del Sud with a proton beam up to 60 MeV and a spatial homogeneity study of the crystal has been performed at Loma Linda University Medical Center with a 100 MeV proton beam. The YAG(Ce) crystal showed a good energy resolution equal to 3.7% at 60 MeV and measurements, performed in the 30-60 MeV proton energy range, were fitted by Birks' equation. Using a silicon tracker to determine the particle entry point in the crystal, a spatial homogeneity value of 1.7% in the light response has been measured.

  2. Dynamics of pulsed holmium:YAG laser photocoagulation of albumen.

    PubMed

    Pfefer, T J; Chan, K F; Hammer, D X; Welch, A J

    2000-05-01

    The pulsed holmium:YAG laser (lambda = 2.12 microm, tau(p) = 250 micros) has been investigated as a method for inducing localized coagulation for medical procedures, yet the dynamics of this process are not well understood. In this study, photocoagulation of albumen (egg white) was analysed experimentally and results compared with optical-thermal simulations to investigate a rate process approach to thermal damage and the role of heat conduction and dynamic changes in absorption. The coagulation threshold was determined using probit analysis, and coagulum dynamics were documented with fast flash photography. The nonlinear computational model, which included a Beer's law optical component, a finite difference heat transfer component and an Arrhenius equation-based damage calculation, was verified against data from the literature. Moderate discrepancies between simulation results and our experimental data probably resulted from the use of a laser beam with an irregular spatial profile. This profile produced a lower than expected coagulation threshold and an irregular damage distribution within a millisecond after laser onset. After 1 ms, heat conduction led to smoothing of the coagulum. Simulations indicated that dynamic changes in absorption led to a reduction in surface temperatures. The Arrhenius equation was shown to be effective for simulating transient albumen coagulation during pulsed holmium:YAG laser irradiation. Greater understanding of pulsed laser-tissue interactions may lead to improved treatment outcome and optimization of laser parameters for a variety of medical procedures.

  3. Underwater cutting technology of thick stainless steel with YAG laser

    NASA Astrophysics Data System (ADS)

    Chida, Itaru; Okazaki, Koki; Shima, Seishi; Kurihara, Kenji; Yuguchi, Yasuhiro; Sato, Ikuko

    2003-03-01

    In nuclear power plants, irradiated materials like Control Rod (CR) should be stored underwater after service. Due to reducing the storage space, underwater cutting technology is expected. In this study, we developed underwater cutting technology of thick stainless steel with YAG laser in order to cut used CR. Preliminary tests were performed with flat plate test-pieces to optimize the cutting conditions. Due to creating a local dry area between nozzle and test-piece, high-pressure air was blown from the nozzle. Underwater laser cutting was carried out by laser irradiation power of 4 kW, changing the parameters of cutting speed, distance between the nozzle and test-piece, and thickness of the test-piece. We also investigated the wastes like dross and aerosols by laser cutting. Amount of dross was approximately 0.1 kg/m after cutting a 14 mm thick stainless steel plate, which is estimated to be less than other cutting method. Based on these results, we developed underwater cutting system of CR test-piece with YAG laser as a mock-up test. In the cutting torch, there was tracking system was introduced to keep the distance between the nozzle and the test-piece constant, and cutting monitor was also set-in to detect whether the test-piece was successfully cut or not. We have already tried to cut the CR test-piece with this facility and successfully cut in half.

  4. Preliminary investigation of CTH:YAG laser for cochlear implantation

    NASA Astrophysics Data System (ADS)

    Shah, Udayan K.; Pawel, Bruce R.; Potsic, William P.

    2000-05-01

    Cochlear implantation is a treatment for deafness that requires the surgical placement of electrodes within the cochlea, using a high-speed drill. While the drill is effective, the tip of the drill or the drill shaft may damage critical adjacent structures, such as the facial nerve. In addition, the narrow working spaces involved in this surgery make the drill a relatively cumbersome tool for such delicate work. The use of a flexible fiber to deliver the laser energy may make the surgery easier by allowing a more maneuverable instrument to access the region, while reducing the risk of injuring adjacent structures. We report our preliminary investigation of fiber delivery of CTH:YAG energy ((lambda) equals 2091 nm) for the purpose of bony ablation. A 550 micron diameter low-OH silica fiber was used to drill through up to 2.5 mm thick human temporal bone specimens. An average of 14 pulses was required for 1 mm thick bones, and an average of 33 pulses required to ablate 2 mm of bone. The holes drilled were precise, and showed limited adjacent tissue effect by gross and histopathologic evaluation. This work demonstrates the effective fiberoptic delivery of CTH:YAG energy for bone ablation. Further work is warranted to explore the clinical possibilities offered by this technique for precise bony ablation with limited adjacent tissue effect.

  5. The Phagocytosis and Toxicity of Amorphous Silica

    PubMed Central

    Costantini, Lindsey M.; Gilberti, Renée M.; Knecht, David A.

    2011-01-01

    Background Inhalation of crystalline silica is known to cause an inflammatory reaction and chronic exposure leads to lung fibrosis and can progress into the disease, silicosis. Cultured macrophages bind crystalline silica particles, phagocytose them, and rapidly undergo apoptotic and necrotic death. The mechanism by which particles are bound and internalized and the reason particles are toxic is unclear. Amorphous silica has been considered to be a less toxic form, but this view is controversial. We compared the uptake and toxicity of amorphous silica to crystalline silica. Methodology/Principal Findings Amorphous silica particles are phagocytosed by macrophage cells and a single internalized particle is capable of killing a cell. Fluorescent dextran is released from endo-lysosomes within two hours after silica treatment and Caspase-3 activation occurs within 4 hours. Interestingly, toxicity is specific to macrophage cell lines. Other cell types are resistant to silica particle toxicity even though they internalize the particles. The large and uniform size of the spherical, amorphous silica particles allowed us to monitor them during the uptake process. In mCherry-actin transfected macrophages, actin rings began to form 1-3 minutes after silica binding and the actin coat disassembled rapidly following particle internalization. Pre-loading cells with fluorescent dextran allowed us to visualize the fusion of phagosomes with endosomes during internalization. These markers provided two new ways to visualize and quantify particle internalization. At 37°C the rate of amorphous silica internalization was very rapid regardless of particle coating. However, at room temperature, opsonized silica is internalized much faster than non-opsonized silica. Conclusions/Significance Our results indicate that amorphous and crystalline silica are both phagocytosed and both toxic to mouse alveolar macrophage (MH-S) cells. The pathway leading to apoptosis appears to be similar in both

  6. Atomic Bond Deficiency Defects in Amorphous Metals

    NASA Astrophysics Data System (ADS)

    Zhu, Aiwu; Shiflet, Gary J.; Poon, S. Joseph

    2012-10-01

    Atomic bond deficiency (BD) is considered to be characteristic structural defects in amorphous metals. They are the necessary feature of local atomic configurations that facilitate various atomic transports under different driving forces. Compared with vacancies in crystalline solids, they are "small" in terms of their formation energies, volume costs, and elementary steps involved in atomic transport. This article reviews the authors' recent efforts made to analyze how various local configurations containing BD are related to amorphous metal's unique characteristics, such as glass transition, diffusion, shear flow, and structural relaxation.

  7. Neutron scattering studies of amorphous Invar alloys

    SciTech Connect

    Fernandez-Baca, J.A.

    1989-01-01

    This paper reviews recent inelastic neutron scattering experiments performed to study the spin dynamics of two amorphous Invar systems: Fe/sub 100-x/B/sub x/ and Fe/sub 90-x/Ni/sub x/Zr/sub 10/. As in crystalline Invar Fe/sub 65/Ni/sub 35/ and Fe/sub 3/Pt, the excitation of conventional long-wavelength spin waves in these amorphous systems cannot account for the relatively rapid change of their magnetization with temperature. These results are discussed in terms of additional low-lying excitations which apparently have a density of states similar to the spin waves.

  8. Thermal conductivity of sputtered amorphous Ge films

    SciTech Connect

    Zhan, Tianzhuo; Xu, Yibin; Goto, Masahiro; Tanaka, Yoshihisa; Kato, Ryozo; Sasaki, Michiko; Kagawa, Yutaka

    2014-02-15

    We measured the thermal conductivity of amorphous Ge films prepared by magnetron sputtering. The thermal conductivity was significantly higher than the value predicted by the minimum thermal conductivity model and increased with deposition temperature. We found that variations in sound velocity and Ge film density were not the main factors in the high thermal conductivity. Fast Fourier transform patterns of transmission electron micrographs revealed that short-range order in the Ge films was responsible for their high thermal conductivity. The results provide experimental evidences to understand the underlying nature of the variation of phonon mean free path in amorphous solids.

  9. Amorphous graphene: a realization of Zachariasen's glass.

    PubMed

    Kumar, Avishek; Wilson, Mark; Thorpe, M F

    2012-12-05

    Amorphous graphene is a realization of a two-dimensional Zachariasen glass as first proposed 80 years ago. Planar continuous random networks of this archetypal two-dimensional network are generated by two complementary simulation methods. In the first, a Monte Carlo bond switching algorithm is employed to systematically amorphize a crystalline graphene sheet. In the second, molecular dynamics simulations are utilized to quench from the high temperature liquid state. The two approaches lead to similar results as detailed here, through the pair distribution function and the associated diffraction pattern. Details of the structure, including ring statistics and angular distortions, are shown to be sensitive to preparation conditions, and await experimental confirmation.

  10. Radiation-induced amorphization of intermetallic compounds

    NASA Astrophysics Data System (ADS)

    Lam, N. Q.; Sabochick, M. J.; Okamoto, P. R.

    1994-06-01

    In the present paper, important results of our recent computer simulation of radiation-induced amorphization in the ordered compounds CuTi and Cu4Ti3 are summarized. The energetic, structural, thermodynamic and mechanical responses of these intermetallics during chemical disordering, point-defect production and heating were simulated, using molecular dynamics and embedded-atom potentials. From the atomistic details obtained, the critical role of radiation-induced structural disorder in driving the crystalline-to-amorphous phase transformation is discussed.

  11. Amorphous Insulator Films With Controllable Properties

    NASA Technical Reports Server (NTRS)

    Alterovitz, Samuel A.; Warner, Joseph D.; Liu, David C.; Pouch, John J.

    1987-01-01

    In experiments described in report, amorphous hydrogenated carbon films grown at room temperature by low-frequency plasma deposition, using methane or butane gas. Films have unique array of useful properties; (a) adhere to wide variety of materials; (b) contain only carbon and hydrogen; (c) smooth and free of pinholes; (d) resistant to attack by moisture and chemicals; and (e) have high electric-breakdown strength and electrical resistivity. Two of optical properties and hardness of this film controlled by deposition conditions. Amorphous a-C:H and BN films used for hermetic sealing and protection of optical, electronic, magnetic, or delicate mechanical systems, and for semiconductor field dielectrics.

  12. Ion bombardment and disorder in amorphous silicon

    SciTech Connect

    Sidhu, L.S.; Gaspari, F.; Zukotynski, S.

    1997-07-01

    The effect of ion bombardment during growth on the structural and optical properties of amorphous silicon are presented. Two series of films were deposited under electrically grounded and positively biased substrate conditions. The biased samples displayed lower growth rates and increased hydrogen content relative to grounded counterparts. The film structure was examined using Raman spectroscopy. The transverse optic like phonon band position was used as a parameter to characterize network order. Biased samples displayed an increased order of the amorphous network relative to grounded samples. Furthermore, biased samples exhibited a larger optical gap. These results are correlated and attributed to reduced ion bombardment effects.

  13. Magnetic Phases in Amorphous Alloys.

    NASA Astrophysics Data System (ADS)

    Mazumdar, Prosenjit

    In magnetic amorphous alloy with competiting exchange interactions, there exists a multicritical point (MCP) in the temperature (T) vs. concentration (x) phase diagram (x(,c), (theta)(,c)). In the present work, the static (equilibrium) magnetic response near the MCP is thoroughly investigated using low, d.c. fields (B(,a) < 10 Oe) in two systems of alloys: (I) Fe(,x)Ni(,75-x)P(,16)B(,6)Al(,3) and (II) Fe(,x)Ni(,80-x)P(,14)B(,6). From the measurements of the reversible magnetization M(x, T, B(,a)), the following notable results are found: (1) The phase diagram exhibits a non-montonic FM-SG transition line (i.e. T(,f)'s) in both the systems. (2) There is a dramatic change in the magnetic response as x goes across x(,c). (3) The magnetization collapses as M(,P) (TURN) (x - x(,c))('0.3(+OR-)0.1) when x (--->) x(,c)('+). (4) The peak susceptibility diverges as (chi)(,P) (TURN) (x(,c) - x)('-1.5(+OR-)0.2) when x (--->) x(,c)('-). (5) The results (2), (3), and (4) are highly suggestive of a percolation transition in the magnetic network at the critical concentration for ferromagnetism (i.e. x(,c)). (6) Dramatic changes in the transition temperatures and a perceptible shift in x(,c) are observed when normal boron is replaced by enriched boron ((TURN)100% B('11)) in the series (I) samples. (7) The non-linear susceptibility ((chi)(,H)) exhibits the expected divergence at T(,g) with 'universal' exponents in concentrated spin glasses. (8) In the latter, a divergence in the linear susceptibility ((chi)(,o)) is observed for the first time. This is attributed to the close proximity of the ferromagnetic phase at x(,c). The study of the irreversible moment M(,i) (x, T, B(,a)) reveals the following: (9) Depending on the various methods of preparation, it is possible to generate states with different values of M(,i) at low T, all of which are stable (metastable) in time. This implies non -ergodic behavior. (10) For re-entrants (x > x(,c)), the amount of freezing achieved viz. M

  14. [Preparation and optical properties of MgAl2O4/Ce:YAG transparent ceramics].

    PubMed

    He, Long-Fei; Fan, Guang-Han; Lei, Mu-Yun; Lou, Zai-Liang; Chen, Zhi-Wu; Xiao, Yao; Zheng, Shu-Wen; Zhang, Tao

    2013-05-01

    High-purity ultrafine MgAl2O4 powder was synthesized by metal-alkoxide method and calcining for 2-4 h. And then MgAl2O4/Ce:YAG transparent ceramics were fabricated by hot-pressed sintering and hot isostatic pressed sintering technique with YAG:Ce powder and MgAl2O4 powder. The transparent ceramics were characterized by XRD, SEM, EDS and fluorescence spectrometer, respectively. The results show that the crystal phase of the transparent ceramic was composed of MgAl2O4 and YAG,and the YAG phase dispersed well in the matrix of MgAl2O4. The excitation spectra had a weak band at 345 nm and a strong band at 475 nm. The broad emission peaks at about 533 nm were attributed to 5d-->4f transition of Ce3+ ions. Decay curves for the fluorescence of MgAl2O4/Ce:YAG transparent ceramic test show that the lifetime of the Ce:YAG glass ceramic was 59.74 ns. All results show that MgAl2O4/Ce:YAG transparent ceramic may be a promising fluorescent material for white LED applications.

  15. Amorphization and nanocrystallization of silcon under shock compression

    SciTech Connect

    Remington, B. A.; Wehrenberg, C. E.; Zhao, S.; Hahn, E. N.; Kad, B.; Bringa, E. M.; Meyers, M. A.

    2015-11-06

    High-power, short-duration, laser-driven, shock compression and recovery experiments on [001] silicon unveiled remarkable structural changes above a pressure threshold. Two distinct amorphous regions were identified: (a) a bulk amorphous layer close to the surface and (b) amorphous bands initially aligned with {111} slip planes. Further increase of the laser energy leads to the re-crystallization of amorphous silicon into nanocrystals with high concentration of nano-twins. This amorphization is produced by the combined effect of high magnitude hydrostatic and shear stresses under dynamic shock compression. Shock-induced defects play a very important role in the onset of amorphization. Calculations of the free energy changes with pressure and shear, using the Patel-Cohen methodology, are in agreement with the experimental results. Molecular dynamics simulation corroborates the amorphization, showing that it is initiated by the nucleation and propagation of partial dislocations. As a result, the nucleation of amorphization is analyzed qualitatively by classical nucleation theory.

  16. Inverted amorphous silicon solar cell utilizing cermet layers

    DOEpatents

    Hanak, Joseph J.

    1979-01-01

    An amorphous silicon solar cell incorporating a transparent high work function metal cermet incident to solar radiation and a thick film cermet contacting the amorphous silicon opposite to said incident surface.

  17. Effect of Er:YAG laser on enamel demineralization around restorations.

    PubMed

    Colucci, Vivian; de Souza Gabriel, Aline Evangelista; Scatolin, Renata Siqueira; Serra, Mônica Campos; Corona, Silmara Aparecida Milori

    2015-05-01

    This study evaluates in situ the effect of erbium-doped yttrium aluminum garnet (Er:YAG) laser parameters on the development of caries-like lesions adjacent to dental restorations. One hundred fifty bovine enamel slabs were randomly allocated among 15 volunteers. The specimens were subdivided into ten groups: nine experimental groups prepared with Er:YAG laser (300 mJ output, frequency of 2, 4 or 6 Hz, water flow rate of 2.0, 5.0, or 8.0 mL/min) and one control group (high-speed handpiece). The prepared cavity was restored with a composite resin, and the slabs were mounted on palatal appliance to be installed in the volunteers to the cariogenic challenge. After this, the specimens were sectioned to the longitudinal microhardness measurements. Data were submitted to Friedman and Wilcoxon paired tests. All groups prepared with Er:YAG laser demonstrated microhardness values higher than those prepared with high-speed handpiece, which showed the lowest microhardness values (24.86). The group prepared with Er:YAG laser (2 Hz-2.0 mL/min) showed the highest microhardness values (152.43), followed by those prepared with Er:YAG laser (2 Hz-5.0 mL/min) (133.08) and Er:YAG laser (2 Hz-8.0 mL/min) (91.61), respectively. The groups Er:YAG laser with 4 and 6 Hz of frequency and water flow rates of 2.0, 5.0, and 8.0 mL/min showed microhardness values lower than the groups cited above and showed statistical similarity among them. The Er:YAG laser parameters employed to cavity preparation influenced the acid resistance of the irradiated substrate, and the Er:YAG laser was capable to control the development of caries-like lesions around composite resin restorations.

  18. Development of YAG:Dy Thermographic Phosphor Coatings for Turbine Engine Applications

    NASA Technical Reports Server (NTRS)

    Eldridge, J. I.; Jenkins, T. P.; Allison, S. W.; Wolfe, D. E.; Jordan, E. H.

    2012-01-01

    The selection and development of thermographic phosphor coatings were pursued to meet the objective of demonstrating luminescence-decay-based temperature measurements up to 1300C on the surface of a vane in an operating demonstrator turbine engine. To meet this objective, YAG:Dy was selected based on the desirable luminescence performance observed for YAG:Dy powder: (1) excellent temperature sensitivity and intensity at operating turbine engine temperatures, (2) an emission peak at the relatively short wavelength of 456 nm, where the interference from background blackbody radiation is fairly low, and (3) its nearly single exponential decay which makes for a simple, reliable temperature calibration. However, implementation of YAG:Dy for surface temperature measurements required application of YAG:Dy as a coating onto the surface of a superalloy component with a preexisting yttria-stabilized zirconia (YSZ) thermal barrier coating (TBC). An inherent dilemma in producing a YAG:Dy coating is that coating processing is constrained to be performed at temperatures below (less than 1200C) what is considered safe for the superalloy component, much lower than temperatures used to produce the high quality crystalline powder. Therefore, YAG:Dy coatings tend to exhibit lower luminescence performance compared to well prepared YAG:Dy powder, and the luminescence performance of the coating will depend on the method of coating deposition. In this presentation, the luminescence performance of YAG:Dy coatings prepared by the different methods of (1) application of a binder-based YAG:Dy-containing paint, (2) solution precursor plasma spray (SPPS), and (3) electron-beam physical vapor deposition (EB-PVD) and the effect of post-deposition heat treatments will be discussed.

  19. Metal electrode for amorphous silicon solar cells

    DOEpatents

    Williams, Richard

    1983-01-01

    An amorphous silicon solar cell having an N-type region wherein the contact to the N-type region is composed of a material having a work function of about 3.7 electron volts or less. Suitable materials include strontium, barium and magnesium and rare earth metals such as gadolinium and yttrium.

  20. Amorphous calcium carbonate particles form coral skeletons.

    PubMed

    Mass, Tali; Giuffre, Anthony J; Sun, Chang-Yu; Stifler, Cayla A; Frazier, Matthew J; Neder, Maayan; Tamura, Nobumichi; Stan, Camelia V; Marcus, Matthew A; Gilbert, Pupa U P A

    2017-08-28

    Do corals form their skeletons by precipitation from solution or by attachment of amorphous precursor particles as observed in other minerals and biominerals? The classical model assumes precipitation in contrast with observed "vital effects," that is, deviations from elemental and isotopic compositions at thermodynamic equilibrium. Here, we show direct spectromicroscopy evidence in Stylophora pistillata corals that two amorphous precursors exist, one hydrated and one anhydrous amorphous calcium carbonate (ACC); that these are formed in the tissue as 400-nm particles; and that they attach to the surface of coral skeletons, remain amorphous for hours, and finally, crystallize into aragonite (CaCO3). We show in both coral and synthetic aragonite spherulites that crystal growth by attachment of ACC particles is more than 100 times faster than ion-by-ion growth from solution. Fast growth provides a distinct physiological advantage to corals in the rigors of the reef, a crowded and fiercely competitive ecosystem. Corals are affected by warming-induced bleaching and postmortem dissolution, but the finding here that ACC particles are formed inside tissue may make coral skeleton formation less susceptible to ocean acidification than previously assumed. If this is how other corals form their skeletons, perhaps this is how a few corals survived past CO2 increases, such as the Paleocene-Eocene Thermal Maximum that occurred 56 Mya.

  1. Plasma deposition of amorphous metal alloys

    DOEpatents

    Hays, A.K.

    1979-07-18

    Amorphous metal alloy coatings are plasma-deposited by dissociation of vapors of organometallic compounds and metalloid hydrides in the presence of a reducing gas, using a glow discharge. Tetracarbonylnickel, phosphine, and hydrogen constitute a typical reaction mixture of the invention, yielding a NiPC alloy.

  2. Structural modeling of amorphous conducting carbon film

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, Somnath; Pati, Swapan K.; Subramanyam, S. V.

    1998-04-01

    Amorphous conducting carbon films are prepared using plasma assisted polymerization process. SEM and TEM shows random aggregate of globular clusters of micron size inside the samples. Electrical measurements indicate a near metallic nature. A tendency of saturation of resistivity at low temperature is observed. From spectroscopic analysis we find some unusual features. Based on these observations a structural model of this carbon is proposed.

  3. Low temperature internal friction of amorphous silicon

    NASA Astrophysics Data System (ADS)

    Liu, Xiao; Metcalf, Thomas; Jernigan, Glenn; Jugdersuren, Battogtokh; Kearney, Brian; Culberston, James

    The ubiquitous low-energy excitations, known as two-level tunnelling systems (TLS), are one of the universal phenomena of amorphous solids. These excitations dominate the acoustic, dielectric, and thermal properties of structurally disordered solids. Using the double-paddle oscillator internal friction measurement technique, we have shown that TLS can be made to almost completely disappear in e-beam deposited amorphous silicon (a-Si) as the growth temperature increased to 400°C. However, there is a mysterious broad maximum in internal friction at 2-3K, which we suspect to come from metallic contamination of our oscillators and is not related to a-Si. Our new result of a-Si, deposited in a different UHV system and on oscillators with a different type of metallic electrodes, confirms our suspicion. This lowers the upper bound of possible TLS content in a-Si, in terms of tunnelling strength, to below 10-6. Our results offer an encouraging opportunity to use growth temperature to improve the structure order of amorphous thin films and to develop high quality amorphous dielectrics for applications, such as in modern quantum devices. Work supported by the Office of Naval Research.

  4. High resolution amorphous silicon radiation detectors

    DOEpatents

    Street, R.A.; Kaplan, S.N.; Perez-Mendez, V.

    1992-05-26

    A radiation detector employing amorphous Si:H cells in an array with each detector cell having at least three contiguous layers (n-type, intrinsic, p-type), positioned between two electrodes to which a bias voltage is applied. An energy conversion layer atop the silicon cells intercepts incident radiation and converts radiation energy to light energy of a wavelength to which the silicon cells are responsive. A read-out device, positioned proximate to each detector element in an array allows each such element to be interrogated independently to determine whether radiation has been detected in that cell. The energy conversion material may be a layer of luminescent material having a columnar structure. In one embodiment a column of luminescent material detects the passage therethrough of radiation to be detected and directs a light beam signal to an adjacent a-Si:H film so that detection may be confined to one or more such cells in the array. One or both electrodes may have a comb structure, and the teeth of each electrode comb may be interdigitated for capacitance reduction. The amorphous Si:H film may be replaced by an amorphous Si:Ge:H film in which up to 40 percent of the amorphous material is Ge. Two dimensional arrays may be used in X-ray imaging, CT scanning, crystallography, high energy physics beam tracking, nuclear medicine cameras and autoradiography. 18 figs.

  5. High resolution amorphous silicon radiation detectors

    DOEpatents

    Street, Robert A.; Kaplan, Selig N.; Perez-Mendez, Victor

    1992-01-01

    A radiation detector employing amorphous Si:H cells in an array with each detector cell having at least three contiguous layers (n type, intrinsic, p type), positioned between two electrodes to which a bias voltage is applied. An energy conversion layer atop the silicon cells intercepts incident radiation and converts radiation energy to light energy of a wavelength to which the silicon cells are responsive. A read-out device, positioned proximate to each detector element in an array allows each such element to be interrogated independently to determine whether radiation has been detected in that cell. The energy conversion material may be a layer of luminescent material having a columnar structure. In one embodiment a column of luminescent material detects the passage therethrough of radiation to be detected and directs a light beam signal to an adjacent a-Si:H film so that detection may be confined to one or more such cells in the array. One or both electrodes may have a comb structure, and the teeth of each electrode comb may be interdigitated for capacitance reduction. The amorphous Si:H film may be replaced by an amorphous Si:Ge:H film in which up to 40 percent of the amorphous material is Ge. Two dimensional arrays may be used in X-ray imaging, CT scanning, crystallography, high energy physics beam tracking, nuclear medicine cameras and autoradiography.

  6. TRANSIENT AMORPHOUS CALCIUM PHOSPHATE IN FORMING ENAMEL

    PubMed Central

    Beniash, Elia; Metzler, Rebecca A.; Lam, Raymond S.K.; Gilbert, P.U.P.A.

    2009-01-01

    Enamel, the hardest tissue in the body, begins as a three-dimensional network of nanometer size mineral particles, suspended in a protein gel. This mineral network serves as a template for mature enamel formation. To further understand the mechanisms of enamel formation we characterized the forming enamel mineral at an early secretory stage using x-ray absorption near-edge structure (XANES) spectromicroscopy, transmission electron microscopy (TEM), FTIR microspectroscopy and polarized light microscopy. We show that the newly formed enamel mineral is amorphous calcium phosphate (ACP), which eventually transforms into apatitic crystals. Interestingly, the size, shape and spatial organization of these amorphous mineral particles and older crystals are essentially the same, indicating that the mineral morphology and organization in enamel is determined prior to its crystallization. Mineralization via transient amorphous phases has been previously reported in chiton teeth, mollusk shells, echinoderm spicules and spines, and recent reports strongly suggest the presence transient amorphous mineral in forming vertebrate bones. The present finding of transient ACP in murine tooth enamel suggests that this strategy might be universal. PMID:19217943

  7. Amorphous calcium carbonate particles form coral skeletons

    PubMed Central

    Mass, Tali; Giuffre, Anthony J.; Sun, Chang-Yu; Stifler, Cayla A.; Frazier, Matthew J.; Neder, Maayan; Tamura, Nobumichi; Stan, Camelia V.; Marcus, Matthew A.

    2017-01-01

    Do corals form their skeletons by precipitation from solution or by attachment of amorphous precursor particles as observed in other minerals and biominerals? The classical model assumes precipitation in contrast with observed “vital effects,” that is, deviations from elemental and isotopic compositions at thermodynamic equilibrium. Here, we show direct spectromicroscopy evidence in Stylophora pistillata corals that two amorphous precursors exist, one hydrated and one anhydrous amorphous calcium carbonate (ACC); that these are formed in the tissue as 400-nm particles; and that they attach to the surface of coral skeletons, remain amorphous for hours, and finally, crystallize into aragonite (CaCO3). We show in both coral and synthetic aragonite spherulites that crystal growth by attachment of ACC particles is more than 100 times faster than ion-by-ion growth from solution. Fast growth provides a distinct physiological advantage to corals in the rigors of the reef, a crowded and fiercely competitive ecosystem. Corals are affected by warming-induced bleaching and postmortem dissolution, but the finding here that ACC particles are formed inside tissue may make coral skeleton formation less susceptible to ocean acidification than previously assumed. If this is how other corals form their skeletons, perhaps this is how a few corals survived past CO2 increases, such as the Paleocene–Eocene Thermal Maximum that occurred 56 Mya. PMID:28847944

  8. Plasma deposition of amorphous metal alloys

    DOEpatents

    Hays, Auda K.

    1986-01-01

    Amorphous metal alloy coatings are plasma-deposited by dissociation of vapors of organometallic compounds and metalloid hydrides in the presence of a reducing gas, using a glow discharge. Tetracarbonylnickel, phosphine, and hydrogen constitute a typical reaction mixture of the invention, yielding a NiPC alloy.

  9. Amorphous Molecular Organic Solids for Gas Adsorption

    SciTech Connect

    Tian, Jian; Thallapally, Praveen K.; Dalgarno, Scott J.; McGrail, B. Peter; Atwood, Jerry L.

    2009-07-06

    We show that molecular organic compounds with large accessible internal cavities, as part of their rigid molecular structure, display exceptional ability for gas storage and separation in the amorphous solid state. This finding suggests for the first time that long-range molecular order is not a prerequisite for organic molecules to be engineered as porous materials

  10. Amorphous calcium carbonate particles form coral skeletons

    NASA Astrophysics Data System (ADS)

    Mass, Tali; Giuffre, Anthony J.; Sun, Chang-Yu; Stifler, Cayla A.; Frazier, Matthew J.; Neder, Maayan; Tamura, Nobumichi; Stan, Camelia V.; Marcus, Matthew A.; Gilbert, Pupa U. P. A.

    2017-09-01

    Do corals form their skeletons by precipitation from solution or by attachment of amorphous precursor particles as observed in other minerals and biominerals? The classical model assumes precipitation in contrast with observed “vital effects,” that is, deviations from elemental and isotopic compositions at thermodynamic equilibrium. Here, we show direct spectromicroscopy evidence in Stylophora pistillata corals that two amorphous precursors exist, one hydrated and one anhydrous amorphous calcium carbonate (ACC); that these are formed in the tissue as 400-nm particles; and that they attach to the surface of coral skeletons, remain amorphous for hours, and finally, crystallize into aragonite (CaCO3). We show in both coral and synthetic aragonite spherulites that crystal growth by attachment of ACC particles is more than 100 times faster than ion-by-ion growth from solution. Fast growth provides a distinct physiological advantage to corals in the rigors of the reef, a crowded and fiercely competitive ecosystem. Corals are affected by warming-induced bleaching and postmortem dissolution, but the finding here that ACC particles are formed inside tissue may make coral skeleton formation less susceptible to ocean acidification than previously assumed. If this is how other corals form their skeletons, perhaps this is how a few corals survived past CO2 increases, such as the Paleocene–Eocene Thermal Maximum that occurred 56 Mya.

  11. High-energy nanosecond radially polarized beam output from Nd:YAG amplifiers

    NASA Astrophysics Data System (ADS)

    Chang, Chengcheng; Chen, Xudong; Pu, Jixiong

    2017-03-01

    Radially polarized laser beam amplification up to the 772 mJ using flash-lamp-pumped Nd:YAG amplifiers was demonstrated. In the experiments, a nanosecond radially polarized seed beam was converted from a conventional Q-switched Nd:YAG laser output with a polarization converter and then amplified with two Nd:YAG amplifier stages. A maximum amplification output energy up to 772 mJ was achieved at 10 Hz with a 10-ns pulse, corresponding to an amplification factor of 323%. Excellent conservation of polarization was also obtained during the amplification.

  12. Laser dyes excited by high PRR Nd:YAG laser second-harmonic radiation

    NASA Astrophysics Data System (ADS)

    Soldatov, A. N.; Donin, V. I.; Jakovin, D. V.; Reimer, I. V.

    2008-01-01

    The lasing characteristics of red-emitting dyes in ethanol excited by Nd:YAG laser second-harmonic radiation are examined. The Nd:YAG laser was pumped by a diode matrix. The pump pulse repetition rates (PRRs) were 2.5 - 10 kHz and the pulse duration was 60 - 300 ns. The following dyes were evaluated: oxazine 17, DCM, DCM sp, and pyridine 1. The conversion efficiency for oxazine was 25 % without wavelength selection and 15 % with wavelength selection over the tuning range from 630 to 700 nm. The Nd:YAG and dye laser designs used are described elsewhere [1,2].

  13. Single-frequency injection-seeded Q-switched Ho:YAG laser

    NASA Astrophysics Data System (ADS)

    Wang, Qing; Gao, Chunqing; Na, Quanxin; Zhang, Yixuan; Ye, Qing; Gao, Mingwei

    2017-04-01

    An injection-seeded Ho:YAG laser at 2090 nm with changeable pulse repetition frequency (PRF) is demonstrated. Containing a Ho:YAG nonplanar ring oscillator (NPRO) seed, a slave laser, and a single-pass amplifier, the laser delivered single-frequency pulses with energy ranging from 31.4 to 12.7 mJ. The corresponding pulse duration and PRF varied between 102-215 ns and 150-750 Hz, respectively. To the best of our knowledge, this is the highest PRF ever obtained from a single-frequency Ho:YAG laser.

  14. Synthesis and characterization of Eu3+:YAG nanopowder by precipitation method

    NASA Astrophysics Data System (ADS)

    Balaji, D.; Thangaraju, D.; Durairajan, A.; Babu, S. Moorthy

    2013-02-01

    Eu3+:Y3Al5O12 (Eu3+:YAG) nanopowder has been synthesized by reverse co-precipitation method. Cubic YAG structure was obtained at 850 °C calcination. FE-SEM micrographs confirm that YAG:Eu3+ particles are homogeneous sphere like morphology with average particle size of 50-70 nm. The crystalline phosphors showed orange - red emission with magnetic dipole transition 5D0→7F1 (590 nm) as most prominent group than forced electric dipole transition 5D0→7F2 (610nm).

  15. Femtosecond laser micromachined ridge waveguide lasers in Nd:YAG ceramics

    NASA Astrophysics Data System (ADS)

    Jia, Yuechen; Vázquez de Aldana, Javier R.; Akhmadaliev, Shavkat; Zhou, Shengqiang; Chen, Feng

    2013-12-01

    We report on the fabrication of ridge waveguides in Nd:YAG ceramic by using femtosecond laser micromachining of the surface of a He ion implanted planar waveguide. Under optical pump of 808 nm light, continuous wave waveguide lasers have been realized at 1.06 μm at room temperature in the Nd:YAG ceramic ridge waveguide system, reaching a maximum output power of 46 mW. The lasing threshold of ˜64.9 mW and the slope efficiency of 42.5% are obtained for the ridge waveguide system, which shows superior lasing performance to the Nd:YAG ceramic planar waveguide.

  16. Improvement of the technique in treatment of internal hemorrhoids with Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Bao, Xiao-qing; Zhu, Jing; Shi, Hong-Min

    2005-07-01

    Objective: To observe and study the improvement of the technique in treatment of internal hemorrhoids with Nd:YAG laser and evaluate the effective rate. Methods: 60 patients of internal hemorrhoids were treated with Nd:YAG laser (10-15mw) irradiating on the mucosa of the lesions. Results: Among 60 patients, 57 patients were primarily cured with one treatment, 3 patients were primarily cured with two treatments. The effective rate was 95% with one treatment, and it reached to 100% with two treatments. Conclusions: the improvement of the technique in treatment of internal hemorrhoids with Nd:YAG laser is effective and easy to operate.

  17. YAG:Ce3+ Nanophosphor Synthesized with the Salted Sol-Gel Method

    SciTech Connect

    D. Jia; C. V. Shaffer; J. E. Weyant; A. Goonewardene; X. Guo; Y. Wang; X. Z. Guo; K. K. Li; Y. K. Zou; W. Jia

    2006-05-01

    Nano-phosphors of Y3Al5O12:Ce3+ (YAG:Ce) were synthesized with a novel salted sol-gel method, in which aqueous solution of inorganic salts (yttrium/cerium nitrates) were used along with the metal alkoxide precursor, aluminum sec-butoxide, Al(OC4H9)3. YAG single phase was formed at temperature as low as 800 C. Luminescence of YAG:Ce reached the maximum intensity when calcined above 1350C. The SEM image reveals that the grain sizes of the nano-phosphors calcined at 1100 C are in a range of 50-150 nm.

  18. Experimental studies on the usage possibilities of the Nd:YAG laser in the cataract surgery

    NASA Astrophysics Data System (ADS)

    Yu, Xiaomin; Ma, Nina; Li, Jiaze

    2005-01-01

    The investigations of used pulsed Q-switched neodymium:YAG laser induced plasma and shock wave during experimental lenses emulsification were presented. The formation and propagation of plasma and shock wave created by the high powered Nd:YAG laser pulses with a titanium target were imaged through optical multiple analysis, and the pressure of shock wave was calculated. The results of shock wave interacting with the lenses material were observed. The lenses, simulated at different hardness, were placed in containers filled with Ringer's solution. The experimental results are promising and show that the Nd:YAG laser can be used for human lens emulsification.

  19. Amorphous silica-like carbon dioxide

    NASA Astrophysics Data System (ADS)

    Santoro, Mario; Gorelli, Federico A.; Bini, Roberto; Ruocco, Giancarlo; Scandolo, Sandro; Crichton, Wilson A.

    2006-06-01

    Among the group IV elements, only carbon forms stable double bonds with oxygen at ambient conditions. At variance with silica and germania, the non-molecular single-bonded crystalline form of carbon dioxide, phase V, only exists at high pressure. The amorphous forms of silica (a-SiO2) and germania (a-GeO2) are well known at ambient conditions; however, the amorphous, non-molecular form of CO2 has so far been described only as a result of first-principles simulations. Here we report the synthesis of an amorphous, silica-like form of carbon dioxide, a-CO2, which we call `a-carbonia'. The compression of the molecular phase III of CO2 between 40 and 48GPa at room temperature initiated the transformation to the non-molecular amorphous phase. Infrared spectra measured at temperatures up to 680K show the progressive formation of C-O single bonds and the simultaneous disappearance of all molecular signatures. Furthermore, state-of-the-art Raman and synchrotron X-ray diffraction measurements on temperature-quenched samples confirm the amorphous character of the material. Comparison with vibrational and diffraction data for a-SiO2 and a-GeO2, as well as with the structure factor calculated for the a-CO2 sample obtained by first-principles molecular dynamics, shows that a-CO2 is structurally homologous to the other group IV dioxide glasses. We therefore conclude that the class of archetypal network-forming disordered systems, including a-SiO2, a-GeO2 and water, must be extended to include a-CO2.

  20. Morphological assessment of dentine and cementum following apicectomy with Zekrya burs and Er:YAG laser associated with direct and indirect Nd:YAG laser irradiation.

    PubMed

    de Moura, Abilio Albuquerque Maranhão; Moura-Netto, Cacio; Barletta, Fernando Branco; Vieira-Júnior, Nilson Dias; Eduardo, Carlos de Paula

    2010-04-01

    This study aimed to assess the apical surface morphology of maxillary central incisors resected 3.0 mm from the tooth apex using Zekrya burs or Er:YAG laser, with or without subsequent direct Nd:YAG laser irradiation (apical and buccal surfaces) and indirect irradiation (palatal surface). Forty maxillary central incisors were instrumented and obturated. The roots were divided into 4 groups according to the root resection method (Zekrya bur or Er:YAG laser - 1.8 W, 450 mJ, 4 Hz, 113 J/cm(2)) and further surface treatment (none or Nd:YAG laser - 2.0 W, 100 mJ, 20 Hz, 124 J/cm(2)). The teeth were prepared for SEM analysis. Scores ranging from 1 to 4 were attributed to cut quality and morphological changes. The data were analyzed by the Kruskal-Wallis test and by Dunn's test. SEM images showed irregular surfaces on the apical portions resected with Zekrya burs, with smear layer and grooves in the resected dentine and slight gutta-percha displacement and plasticization. On the other hand, apicectomies carried out with Er:YAG laser showed morphological changes compatible with ablated dentine, with rough surfaces and craters. In spite of the presence of plasticized gutta-percha, with the presence of bubbles, an irregular adaptation of the filling material to the root walls was also observed. Direct Nd:YAG laser irradiation of the apical and buccal surfaces of the resected roots resulted in areas of resolidification and fusion in the dentine and cementum, with a vitrified aspect; indirect Nd:YAG laser irradiation of the palatal surfaces yielded a lower number of changes in the cementum, with irregular resolidification areas. There were no differences in terms of cut quality between the use of burs and Er:YAG laser or between the 2 surfaces (apical and buccal) treated with Nd:YAG laser with direct irradiation. However, morphological changes were significantly less frequent on surfaces submitted to indirect irradiation (palatal) when compared with those directly irradiated

  1. Q-switched Nd:YAG optical vortex lasers.

    PubMed

    Kim, D J; Kim, J W; Clarkson, W A

    2013-12-02

    Q-switched operation of a high-quality Nd:YAG optical vortex laser with the first order Laguerre-Gaussian mode and well-determined helical wavefronts using a fiber-based pump beam conditioning scheme is reported. A simple two-mirror resonator incorporating an acousto-optic Q-switch was employed, along with an etalon and a Brewster plate to enforce the particular helicity of the output. The laser yielded Q-switched pulses with ~250 μJ pulse energy and ~33 ns pulse duration (FWHM) at a 0.1 kHz repetition rate for 5.1 W of absorbed pump power. The handedness of the helical wavefronts was preserved regardless of the repetition rates. The prospects of further power scaling and improved laser performance are discussed.

  2. Clad Nd:YAG fibers for laser applications

    SciTech Connect

    Digonnet, M.J.F.; Shaw, H.J.; Gaeta, C.J.; O'meara, D.

    1987-05-01

    The implementation of an extrusion method to clad Nd:YAG single crystal fibers with index-matched glasses (Delta-n = 0.048) is reported. A propagation-loss coefficient of 0.08 dB/cm was measured for the fundamental mode of a 41-micron-diameter glass-clad fiber laser, an improvement of about one order of magnitude over unclad fibers. Guided clad fiber lasers operated at 1.064 microns with thresholds as low as 0.3-0.5 mW and up to 65-mW CW output power are also reported. The origins of and means of reducing the residual loss are discussed. 14 references.

  3. [Nd-YAG laser in otorhinolaryngology: our experience].

    PubMed

    Amato, G; Galletta, A; Paternò, A

    1996-04-01

    The Authors describe Nd-YAG Laser treatment in dealing with some of the most common hypertrophic-hyperplastic pathologies of the upper airways. Laser operations are performed under local anesthesia employing an Endo-Video-Telecamera in order to treat soft surgical targets not reachable otherwise. The Authors stress the numerous advantages of this techniques: high surgical accuracy, poor collateral intro- and post-operative effects, lack of post-operative intranasal packing, quick recovery time, absence of relapse, sparing of nasal physiology. Furthermore patient of the treatment acceptance and low sanitary expenses, are additional favorable factors. The Authors explain the details of the methods, emphasize the tolerability of the treatment and report the results obtained during two years of experience.

  4. Numerical simulation of a battlefield Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Henriksson, Markus; Sjoqvist, Lars; Uhrwing, Thomas

    2005-11-01

    A numeric model has been developed to identify the critical components and parameters in improving the output beam quality of a flashlamp pumped Q-switched Nd:YAG laser with a folded Porro-prism resonator and polarization output coupling. The heating of the laser material and accompanying thermo-optical effects are calculated using the finite element partial differential equations package FEMLAB allowing arbitrary geometries and time distributions. The laser gain and the cavity are modeled with the physical optics simulation code GLAD including effects such as gain profile, thermal lensing and stress-induced birefringence, the Pockels cell rise-time and component aberrations. The model is intended to optimize the pumping process of an OPO providing radiation to be used for ranging, imaging or optical countermeasures.

  5. Front-end system for Yb : YAG cryogenic disk laser

    SciTech Connect

    Perevezentsev, E A; Mukhin, I B; Kuznetsov, I I; Vadimova, O L; Palashov, O V

    2015-05-31

    A new front-end system for a cryogenic Yb : YAG laser is designed. The system consists of a femtosecond source, a stretcher and a regenerative amplifier with an output energy of 25 μJ at a pulse repetition rate of 49 kHz, a pulse duration of ∼2 ns and a bandwidth of ∼1.5 nm. After increasing the pump power of the regenerative amplifier, it is expected to achieve a pulse energy of ∼1 mJ at the input to cryogenic amplification stages, which will allow one to obtain laser pulses with a duration of several picoseconds at the output of the cryogenic laser after compression. (extreme light fields and their applications)

  6. Amalgam ablation with the Er:YAG laser

    NASA Astrophysics Data System (ADS)

    Wigdor, Harvey A.; Visuri, Steven R.; Walsh, Joseph T., Jr.

    1995-04-01

    Any laser that will be used by dentist to replace the dental drill (handpiece) must remove dental hard tissues safely. These lasers must also have the ability to ablate the restorative dental materials which are present in the teeth being treated. Prior to any laser being used to treat humans a thorough knowledge of the effects of the laser treatment on dental materials must be understood. Cores of dental amalgam were created and sliced into thin wafers for this experiment. Ablation efficiency and thermal changes were evaluated with and without water. It appears as if the Er:YAG laser can effectively ablate amalgam dental material with and without water. The water prevents the temperature from increasing much above baseline and does not reduce efficiency of ablation.

  7. Er:YAG laser for endodontics: efficiency and safety

    NASA Astrophysics Data System (ADS)

    Hibst, Raimund; Stock, Karl; Gall, Robert; Keller, Ulrich

    1997-12-01

    Recently it has been shown that bacterias can be sterilized by Er:YAG laser irradiation. By optical fiber transmission the bactericidal effect can also be used in endodontics. In order to explore potential laser parameters, we further investigated sterilization of caries and measured temperatures in models simulating endodontic treatment. It was found out that the bactericidal effect is cumulative, with single pulses being active. This offers to choose all laser parameters except pulse energy (radiant exposure) from technical, practical or safety considerations. For clinical studies the following parameter set is proposed for efficient and safe application (teeth with a root wall thickness > 1 mm, and prepared up to ISO 50): pulse energy: 50 mJ, repetition rate: 15 Hz, fiber withdrawal velocity: 2 mm/s. With these settings 4 passes must be performed to accumulate the total dose for sterilization.

  8. Use of the holmium:YAG laser in urology

    NASA Astrophysics Data System (ADS)

    Mattioli, Stefano

    1997-12-01

    The Holmium-YAG is a versatile laser with multiple soft- tissue applications including tissue incision and vaporization, and pulsed-laser applications such as lithotripsy. At 2140 nanometers, the wavelength is highly absorbed by tissue water. Further, like CO2 laser, the Holmium produces immediate tissue vaporization while minimizing deep thermal damage to surrounding tissues. It is an excellent instrument for endopyelotomy, internal urethrotomy, bladder neck incisions and it can be used to resect the prostate. The Holmium creates an acute TUR defect which gives immediate results like the TURP. More than 50 patients were treated from Jan. 1996 to Jan. 1997 for obstructive symptoms due to benign prostatic hyperplasia, bladder neck stricture, urethral stenosis, and superficial bladder tumors.

  9. LED pumped Nd:YAG laser development program

    NASA Technical Reports Server (NTRS)

    Farmer, G. I.; Kiang, Y. C.; Lynch, R. J.

    1973-01-01

    The results of a development program for light emitting diode (LED) pumped Nd:YAG lasers are described. An index matching method to increase the coupling efficiency of the laser is described. A solid glass half-cylinder of 5.0 by 5.6 centimeters was used for index matching and also as a pumping cavity reflector. The laser rods were 1.5 by 56 millimeters with dielectric coatings on both end surfaces. The interfaces between the diode array, glass cylinder, and laser rod were filled with viscous fluid of refractive index n = 1.55. Experiments performed with both the glass cylinder and a gold coated stainless steel reflector of the same dimensions under the same operating conditions indicate that the index matching cylinder gave 159 to 200 percent improvement of coupling efficiency over the metal reflector at various operating temperatures.

  10. Coaxial monitoring of keyhole during Yb:YAG laser welding

    NASA Astrophysics Data System (ADS)

    Kim, Cheol-Hee; Ahn, Do-Chang

    2012-09-01

    In laser remote welding using a scanner, high-speed welding can be achieved by using a 6-axial robot and a galvanometric mirror. In this system, because the laser projection point changes depending on the mirror's position, coaxial monitoring is required to track welding phenomena. This paper presents coaxial monitoring of the keyhole generated by an Yb:YAG laser beam during laser lap welding of steel and Al sheets. A coaxial image camera and a coaxial illumination laser are integrated into the proposed monitoring system. The areas of the keyhole and the full penetration hole were calculated by image processing, and their behaviours were investigated under various welding conditions. The keyhole was monitored using various band-pass filters and a coaxial illumination laser. Adequate filters were suggested for steel and Al alloy welding.

  11. A new contact neodymium: YAG laser for cyclophotocoagulation

    SciTech Connect

    Iwach, A.G.; Drake, M.V.; Hoskins, H.D. Jr.; Schuster, B.L.; Vassiliadis, A.; Crawford, J.B.; Hennings, D.R. )

    1991-06-01

    A newly developed compact (40 kg), self-contained contact Neodymium:YAG laser produces high-peak, high-energy (800 mJ/pulse), short (1.0 millisecond) pulses with 1 to 3 pulses/exposure. Energy is delivered via a 320-microns cleaved quartz fiber optic probe. Cyclophotocoagulation was performed in five eyes of three medium-sized Dutch-pigmented rabbits. The eyes received exposures of 1 to 3 pulses/exposure. Energy delivered ranged from 100 to 800 mJ/pulse. Histopathology revealed ciliary body disruption and hemorrhage with no damage to overlying sclera. When used for transscleral cyclodiathermy in the rabbit, the laser created significant ciliary body disruption with minimal scleral injury.

  12. Resonantly pumped high efficiency Ho:YAG laser.

    PubMed

    Shen, Ying-Jie; Yao, Bao-Quan; Duan, Xiao-Ming; Dai, Tong-Yu; Ju, You-Lun; Wang, Yue-Zhu

    2012-11-20

    High-efficient CW and Q-switched Ho:YAG lasers resonantly dual-end-pumped by two diode-pumped Tm:YLF lasers at 1908 nm were investigated. A maximum slope efficiency of 74.8% in CW operation as well as a maximum output power of 58.7 W at 83.2 W incident pump power was achieved, which corresponded to an optical-to-optical conversion efficiency of 70.6%. The maximum pulse energy of 2.94 mJ was achieved, with a 31 ns FWHM pulse width and a peak power of approximately 94.7 kW.

  13. Single, composite, and ceramic Nd:YAG 946-nm lasers

    NASA Astrophysics Data System (ADS)

    Lan, Rui-Jun; Yang, Guang; Zheng-Ping, Wang

    2015-06-01

    Single, composite crystal and ceramic continuous wave (CW) 946-nm Nd:YAG lasers are demonstrated, respectively. The ceramic laser behaves better than the crystal laser. With 5-mm long ceramic, a CW output power of 1.46 W is generated with an optical conversion efficiency of 13.9%, while the slope efficiency is 17.9%. The optimal ceramic length for a 946-nm laser is also calculated. Project supported by the National Natural Science Foundation of China (Grant No. 61405171), the Natural Science Foundation of Shandong Province, China (Grant No. ZR2012FQ014), and the Science and Technology Program of the Shandong Higher Education Institutions of China (Grant No. J13LJ05).

  14. Diode - Pumped Nd:YAG Lidar for Airborne Cloud Measurements

    NASA Technical Reports Server (NTRS)

    Mehnert, A.; Halldorsson, TH.; Herrmann, H.; Haering, R.; Krichbaumer, W.; Streicher, J.; Werner, CH.

    1992-01-01

    This work is concerned with the experimental method used to separate scattering and to use it for the determination of cloud microphysical parameters. It is also the first airborne test of a lidar version related to the ATLID Program - ESA's scheduled spaceborne lidar. The already tested DLR microlidar was modified with the new diode-pumped laser and a faster data recording system was added. The system was used during the CLEOPATRA campaign in the DLR research aircraft Falcon 20 to measure cloud parameters. The diode pumped Nd:YAG laser we developed for the microlidar is a modification of the laser we introduced at the Lidar Congress at 'Laser 1991' in Munich. Various aspects of this work are discussed.

  15. Clinical evaluation of Er:YAG laser caries treatment

    NASA Astrophysics Data System (ADS)

    Dostalova, Tatjana; Jelinkova, Helena; Kucerova, Hana; Krejsa, Otakar; Hamal, Karel; Kubelka, Jiri; Prochazka, Stanislav

    1997-05-01

    To prepare the enamel, the energy used was mainly 345 mJ and repetition rate 2 Hz, for dentine the optimal energy of Er:YAG drilling machine was 200 mJ and repetition rate from 1 to 2 Hz, depending on cavity depth. Subject of treatment were caries of enamel and dentine and it was possible to remove the old insufficient fillings. The average number of pulses was 111.22, ranging from 16 to 489. During preparation, vibrations of microexplosions were felt by 8 patients, however, neither pain or unpleasant sensations were experienced. The filling materials used were composite resins and glassionomer cements. Their clinical evaluation 6 months post insertion was similar to that of the classical drilling system.

  16. Segmental irradiation of the bladder with neodymium YAG laser irradiation

    SciTech Connect

    McPhee, M.S.; Mador, D.R.; Tulip, J.; Ritchie, B.; Moore, R.; Lakey, W.H.

    1982-11-01

    The Neodymium YAG laser energy source can be readily adapted for cystoscopic use by some simple modifications of existing urologic equipment. Both the fiberoptic resectoscope and a deflecting cystourethroscope have been adapted for this purpose. Fixation of the fiber tip 1 cm. from the target and use of a divergent beam of 36 degrees allows the delivery of standardized dosage to a relatively large bladder tissue volume. Animal experiments involving 35 mongrel dogs established that repetitive overlapping doses of 200 joules ech can successfully treat a large area of bladder resulting in a full thickness bladder wall injury. This technique has been used in 4 high risk patients with infiltrating bladder cancer without adverse sequelae. The ability to reliably produce a full thickness lesion may give this modality a therapeutic advantage over conventional cautery techniques especially for the treatment of residual infiltrative carcinoma.

  17. Mode-locked frequency doubled Nd:YAG laser

    NASA Technical Reports Server (NTRS)

    Brookman, J. S.

    1976-01-01

    The design, fabrication, test, and delivery of two mode-locked, frequency doubled Nd:YAG laser systems are described. Each system was comprised of two units, the laser head and optics on an Invar plate and the electronics control unit in a relay rack chassis panel. Laser number one operated at a repetition rate of 400 MHz and was designed for use in an optical communication system. Laser number two operated at 200 MHz repetition rate and was designed for optical ranging and target signature experiments. Both lasers had a pulse width of 200 ps at the 10% amplitude points at 1.064 micrometer wavelength (150 ps at 0.532 micrometers) with an amplitude stability of + or - 4%. Output power exceeded the design goals.

  18. Length controlled stabilized mode-lock ND:YAG laser

    NASA Technical Reports Server (NTRS)

    Sigfred, J. (Inventor)

    1977-01-01

    A method and apparatus for stabilizing the amplitude and repetition rate of mode-locked Nd:YAG laser pulses by controlling the laser length through a feedback loop are described. The end mirror of the laser is mounted on a piezoelectric crystal which is dithered at a low frequency. A portion of fundamental 1.06 micrometer laser radiation is converted into its second harmonic frequency, and the average power of the second harmonic frequency is detected by an integrating detector. The amount of the power of the second harmonic frequency depends on the match between the optical length of the laser cavity and the mode-lock frequency. The length is controlled by a feedback loop which phase compares the output of the second harmonic detector to the piezoelectric crystal dither signal.

  19. Comparison between the perfomance of Nd:YAG, Nd/Cr:GSGG and Nd/Cr:YAG ceramic lasers with quasi-solar pumping

    NASA Astrophysics Data System (ADS)

    Bouadjemine, R.; Louhibi, D.; Kellou, A.

    2015-01-01

    Recent developments in laser materials, such as Nd/Cr:YAG ceramic with a broad absorption spectrum in the visible, have been applied to achieve highly-efficient and low-cost optical pumping by conventional sources. Our simulator based on the implementation of a mathematical model under Matlab Simulink allowed us to show the correlation between the characteristics of the laser mode of operation (such as Relaxation, Quasi-continuous wave (QCW), Continuous wave, Burst, Q-switched) and the various physical parameters of the oscillator. This model was applied to the Nd:YAG crystal, Nd/Cr:GSGG crystal and Nd/Cr:YAG ceramic. The simulation results demonstrated that Nd/Cr:YAG ceramic is an excellent candidate for solar and quasi-solar pumping, as its pumping efficiency exceeds by a factor of four that of the Nd:YAG crystal medium, and by a factor of two that of Nd/Cr:GSGG crystal. A pumping by a light guide was considered in this simulation.

  20. Deep sclerectomy using erbium:YAG laser in pigs eyes

    NASA Astrophysics Data System (ADS)

    Badr, Yehia A.; Taher, Ibrahim M.; Bahgat, Mostafa M.; Ghoneim, Dina F.

    2004-07-01

    The potential benefits of using pulsed Erbium: YAG laser in removing the deep lamella of the sclera during the procedure of deep sclerectomy was studied. Thirty porcine eyes were divided into 3 groups. A superficial lamellar scleral flap with an area of 5x5 mm as for trabeculectomy was surgically prepared. Using an Erbium: YAG laser (2.94 micron), the deep lamella with an area of 3x1.8 mm was removed. Group I was subjected to an energy level of 40-60 m.J, Descemet's membrane was preserved and trabecular meshwork was left intact and no thermal damage on the contiguous structures in all eyes, group II to 60-80 m.J Descemet's membrane was ruptured in 30% (3 eyes), thermal damage was 20% (2 eyes) on superficial structures, while group III to 80-100m.J there was a high risk of rupture of Descemet's membrane 50% (5 eyes), thermal damage was 30%(3 eyes) on superficial structures & 20%(2 eyes) on deep & superficial structures. Eyes were analyzed histologically by electron microscopy to study Descemet's membrane & the trabecular meshwork & the thermal damage on contiguous structures. Eyes with rupture of Descemet's membrane had total energy power of 11.75 J +/- 6.39, average power was 0.58W +/- 0.07 & power density 1155W/cm2 +/- 144, compared to eyes with no rupture 24.23J +/- 11.77 total energy power, 0.46W average power & 916.4W/cm2 +/- 227 power density. Thermal damage changes occurred at total energy power of 10.14 J, average power was 0.59W & power density 1180W/cm2, compared to eyes with no rupture 24.17J total energy power, 0.46W average power & 919.1W/cm2 power density.

  1. Er:YAG laser technology for remote sensing applications

    NASA Astrophysics Data System (ADS)

    Chen, Moran; Burns, Patrick M.; Litvinovitch, Viatcheslav; Storm, Mark; Sawruk, Nicholas W.

    2016-10-01

    Fibertek has developed an injection locked, resonantly pumped Er:YAG solid-state laser operating at 1.6 μm capable of pulse repetition rates of 1 kHz to 10 kHz for airborne methane and water differential absorption lidars. The laser is resonantly pumped with a fiber-coupled 1532 nm diode laser minimizing the quantum defect and thermal loading generating tunable single-frequency output of 1645-1646 nm with a linewidth of < 100 MHz. The frequency-doubled 1.6 μm Er:YAG laser emits wavelengths in the 822-823 nm spectrum, coincident with water vapor lines. Various cavity designs were studied and optimized for compactness and performance, with the optimal design being an injection seeded and locked five-mirror ring cavity. The laser generated 4 W of average power at pulse repetition frequencies (PRFs) of 1 kHz and 10 kHz, corresponding to 4 mJ and 400 μJ pulse energies, respectively. The 1645 nm was subsequently frequency doubled to 822.5 nm with a 600 pm tuning range covering multiple water absorption lines, with a pulse energy of 1 mJ and a pulse repetition frequency of 1 kHz. The resonator cavity was locked to the seed wavelength via a Pound Drever Hall (PDH) technique and an analog Proportional Integral Derivative (PID) Controller driving a high-bandwidth piezoelectric (PZT)-mounted cavity mirror. Two seed sources lasing on and off the methane absorption line were optically switched to tune the resonator wavelength on and off the methane absorption line between each sequential output pulse. The cavity locking servo maintained the cavity resonance for each pulse.

  2. High-average-power diode-pumped Yb: YAG lasers

    SciTech Connect

    Avizonis, P V; Beach, R; Bibeau, C M; Emanuel, M A; Harris, D G; Honea, E C; Monroe, R S; Payne, S A; Skidmore, J A; Sutton, S B

    1999-10-01

    A scaleable diode end-pumping technology for high-average-power slab and rod lasers has been under development for the past several years at Lawrence Livermore National Laboratory (LLNL). This technology has particular application to high average power Yb:YAG lasers that utilize a rod configured gain element. Previously, this rod configured approach has achieved average output powers in a single 5 cm long by 2 mm diameter Yb:YAG rod of 430 W cw and 280 W q-switched. High beam quality (M{sup 2} = 2.4) q-switched operation has also been demonstrated at over 180 W of average output power. More recently, using a dual rod configuration consisting of two, 5 cm long by 2 mm diameter laser rods with birefringence compensation, we have achieved 1080 W of cw output with an M{sup 2} value of 13.5 at an optical-to-optical conversion efficiency of 27.5%. With the same dual rod laser operated in a q-switched mode, we have also demonstrated 532 W of average power with an M{sup 2} < 2.5 at 17% optical-to-optical conversion efficiency. These q-switched results were obtained at a 10 kHz repetition rate and resulted in 77 nsec pulse durations. These improved levels of operational performance have been achieved as a result of technology advancements made in several areas that will be covered in this manuscript. These enhancements to our architecture include: (1) Hollow lens ducts that enable the use of advanced cavity architectures permitting birefringence compensation and the ability to run in large aperture-filling near-diffraction-limited modes. (2) Compound laser rods with flanged-nonabsorbing-endcaps fabricated by diffusion bonding. (3) Techniques for suppressing amplified spontaneous emission (ASE) and parasitics in the polished barrel rods.

  3. Nd:YAG Laser Treatment of Keloids and Hypertrophic Scars

    PubMed Central

    Akaishi, Satoshi; Koike, Sachiko; Dohi, Teruyuki; Kobe, Kyoko; Hyakusoku, Hiko; Ogawa, Rei

    2012-01-01

    Pathological cutaneous scars such as keloids and hypertrophic scars (HSs) are characterized by a diffuse redness that is caused by the overgrowth of capillary vessels due to chronic inflammation. Our group has been using long-pulsed, 1064-nm Nd:YAG laser in noncontact mode with low fluence and a submillisecond pulse duration to treat keloids and hypertrophic scars since 2006 with satisfactory results. The present study examined the efficacy of this approach in 22 Japanese patients with keloids (n = 16) or hypertrophic scars (n = 6) who were treated every 3 to 4 weeks. Treatment settings were as follows: 5 mm spot size diameter; 14 J/cm2 energy density; 300 μs exposure time per pulse; and 10 Hz repetition rate. The responses of the pathological scars to the treatment were assessed by measuring their erythema, hypertrophy, hardness, itching, and pain or tenderness. Moreover, skin samples from 3 volunteer patients were subjected to histological evaluation and 5 patients underwent thermography during therapy. The average total scar assessment score dropped from 9.86 to 6.34. Hematoxylin and eosin staining and Elastica Masson-Goldner staining showed that laser treatment structurally changed the tissue collagen. This influence reached a depth of 0.5 to 1 mm. Electron microscopy revealed plasma protein leakage, proteoglycan particles, and a change in the collagen fiber fascicles. Further analyses revealed that noncontact mode Nd:YAG laser treatment is highly effective for keloids and hypertrophic scars regardless of patient age, the origin and multiplicity of scarring, the location of the scar(s), or the tension on the scar. PMID:22259645

  4. Design of Er:YAG laser blood-sampling device

    NASA Astrophysics Data System (ADS)

    Wu, Zhi-chao; Jin, Guang-yong; Tan, Xue-chun; Ling, Ming; Liang, Zhu

    2009-07-01

    Laser blood-sampling device is one of the foremost tasks in medicine domain. It has a lot of merits such as un-touching, avoiding infection, indolence, and fast healing etc. The Er:YAG laser with wavelength of 2.94μm which is just close to the absorbency peak of water can be strongly absorbed by water molecular, so it has very wide application value in clinical medicine. In the paper, based on the mutual action characters of the laser with 2.94μm wave length on biological tissues, such as high absorption, acting on surface, the design of a new type of laser blood-sampling device is introduced. According to the needs of practice, the main component of the blood-sampling device is the laser, which includes optical resonator, optical collector, pumping source, optical guidance and focusing system. All of them are designed in the paper, and the reflection index of output coupling mirror of laser is optimized, the laser threshold is reduced, and pumping efficiency is improved. Moreover, thermal effect of Er:YAG solid-state laser is analyzed and a reasonable cooling method is designed. As a result, an excellent laser blood- sampling is obtained, the maximum output power is about 1J, the optical to optical conversion efficiency is 1.2%. For the better production-grade, the cuprum-based conduction is adopt to eliminate heat, the precision modulation and fixing of the optical resonance is achieved by the special adjusting structure that not only improve the stability and reliability, but also reduce the size of laser bloodsampling device. The size is 110×190×320mm, the weight is about 5.8kg, and the laser blood- sampling efficiency is 100%.

  5. Noncontact Er:YAG laser ablation: clinical evaluation.

    PubMed

    Dostálová, T; Jelínková, H; Kucerová, H; Krejsa, O; Hamal, K; Kubelka, J; Procházka, S

    1998-10-01

    The aim of this study is to evaluate the quality of laser ablation in comparison with the classical drilling preparation. For the experiment, the Er:YAG laser drilling machine was used. The system had a laser head, water cooler, and power supply with automatic control. Spot size of 300-350 microns was used for the preparation. Repetition rate of 1-4 Hz, and pulse energies of 100-400 mJ with water spray were chosen. Cavity shape in comparison with classical drill, time of preparation, and influence of cavity shape on filling materials retention in accordance with the U.S. Public Health Service System were used. The evaluation criteria for noncontact Er:YAG ablation were done. The cavity shape is irregular, but spot surface has larger area and microretentive appearance. Caries of enamel and dentin were treated with a noncontact preparation. It was possible to remove the old insufficient fillings, except for amalgam or metal alloys. The average number of pulses was 111.22 (SE 67.57). Vibrations of microexplosions during preparation were felt by patients on 14 cavities; however, nobody felt unpleasant pain. The qualities of filling materials in laser cavities were very stable; however, cavo surface margin discoloration of 82-86% of Alfa rating could be a problem. Changes of the color and anatomic form of the tooth were observed in 4-8%. In comparison with the classical treatment, it could be said that the retention and quality of filling materials is the same or very similar.

  6. SEM investigation of Er:YAG laser apical preparation

    NASA Astrophysics Data System (ADS)

    Bǎlǎbuc, Cosmin; Todea, Carmen; Locovei, Cosmin; RǎduÅ£ǎ, Aurel

    2016-03-01

    Endodontic surgery involves the incision and flap elevation, the access to the root tip, its resection, the cavity retrograde preparation and filling it with biocompatible material that provides a good seal of the apex[1]. Apicoectomy is compulsory in endodontic surgery. The final stage involves the root retropreparation and the carrying out of the retrograde obturation. In order to perform the retrograde preparation the endodontist can use various tools such as lowspeed conventional handpieces, sonic and ultrasonic equipment. The ideal depth of the preparation should be 3 mm, exceeding this value may affect the long-term success of the obturation [2]. Resection at the depth of 3 mm reduces apical ramifications by 98% and lateral root canals by 93%. The ultrasonic retropreparation has numerous advantages compared to the dental drill. Firstly, the cavity will be in the axis of the tooth which implies a minimum destruction of the root canal morphology. The preparations are precise, and the cutting pattern is perpendicular to the long axis of the root, the advantage being the reduction in the number of dentinal tubules exposed at the resected area [3]. Therefore, the retrograde filling is the procedure when an inert and non-toxic material is compacted in the apically created cavity.[4,5]. The Er:YAG laser is the most common wavelength indicated for dental hard tissue preparation. Its natural selectivity offers a significant advantage compared to the conventional hard tissue preparation [6-9].The purpose of this in vitro study was to investigate the quality of Er:YAG laser apical third preparation using Scanning Electron Microscopy (SEM), in comparison with the conventional ultrasonic method.

  7. Fabricating amorphous silicon solar cells by varying the temperature _of the substrate during deposition of the amorphous silicon layer

    DOEpatents

    Carlson, David E.

    1982-01-01

    An improved process for fabricating amorphous silicon solar cells in which the temperature of the substrate is varied during the deposition of the amorphous silicon layer is described. Solar cells manufactured in accordance with this process are shown to have increased efficiencies and fill factors when compared to solar cells manufactured with a constant substrate temperature during deposition of the amorphous silicon layer.

  8. Defect-induced solid state amorphization of molecular crystals

    NASA Astrophysics Data System (ADS)

    Lei, Lei; Carvajal, Teresa; Koslowski, Marisol

    2012-04-01

    We investigate the process of mechanically induced amorphization in small molecule organic crystals under extensive deformation. In this work, we develop a model that describes the amorphization of molecular crystals, in which the plastic response is calculated with a phase field dislocation dynamics theory in four materials: acetaminophen, sucrose, γ-indomethacin, and aspirin. The model is able to predict the fraction of amorphous material generated in single crystals for a given applied stress. Our results show that γ-indomethacin and sucrose demonstrate large volume fractions of amorphous material after sufficient plastic deformation, while smaller amorphous volume fractions are predicted in acetaminophen and aspirin, in agreement with experimental observation.

  9. Flashlamp Pumped, Room Temperature, Nd:YAG Laser Operating at 0.946 Micrometers

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Murray, Keith E.; Walsh, Brian M.

    1998-01-01

    Room temperature operation of flashlamp pumped Nd:YAG at 0.946 micrometers was achieved with a laser rod having undoped ends. Performance was characterized and compared with 1.064 micrometer operation and other quasi four level lasers.

  10. Transpupillary CW YAG laser coagulation. A comparison with argon green and krypton red lasers.

    PubMed

    Peyman, G A; Conway, M D; House, B

    1983-08-01

    The authors have developed a CW YAG laser for transpupillary coagulation. The effects of CW YAG coagulation on the retina, retinal vessels, and fovea were compared with those produced by the krypton red and argon green lasers. To produce threshold coagulative lesions in monkeys and rabbits, we needed five to ten times more energy with the CW YAG than with the krypton red or argon green lasers. Nerve fiber damage was observed only when coagulating retinal vessels with the argon green laser. At the parameters used, none of the lasers damaged the sensory retina of the fovea. The CW YAG may be used as a new mode of laser coagulation in the treatment of retinal diseases.

  11. A Continuous-Wave Diode-Side-Pumped Tm:YAG Laser with Output 51 W

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao-Fu; Xu, Yi-Ting; Li, Cheng-Ming; Zong, Nan; Xu, Jia-Lin; Cui, Qian-Jin; Lu, Yuan-Fu; Bo, Yong; Peng, Qin-Jun; Cui, Da-Fu; Xu, Zu-Yan

    2008-10-01

    A compact diode-side-pumped Tm:YAG laser is presented, which can output 51 W of cw power at 2.02μm. The Tm:YAG rod is side pumped by nine diode arrays with the central wavelength of 783nm and the with bandwidth of about 2.5 nm at 25° C. To decrease the thermal effect on the both ends and dissipate the heat effectively, one composite Tm:YAG rod with the undoped YAG end caps and the screw threads on the side surface of the rod is used as the laser crystal. The maximum optical-to-optical conversion efficiency of the 2.02-μm laser output is 14.2%, with a slope efficiency of 26.8%.

  12. Analysis on the effect of urethra caruncle treated by Ho:YAG laser

    NASA Astrophysics Data System (ADS)

    Zhang, Mei-Jue; Zhu, Jing; Shi, Hong-Min

    2005-07-01

    Objective: To observe the effect of Ho:YAG laser in treatment of urethra cauncle. Methods: The patients suffering from urethra cauncle were treated by Ho:YAG laser, the energy of per pulse is 0.5J. The frequency of pulse is 5~15Hz, and the average power of the laser is 2.5~7.5W. Results: Among the patients 188 cases of urethra cauncle were only cured for one time, twice for12 cases. No stricture on the peristome of urethra or urethrovaginal fistula was observed. Conclusions: The technique of treatment of urethra cauncle with Ho:YAG laser is an effect and safe therapeutics with the merit of excellent homeostasis, improved visualization, minimal thermal damage to surrounding tissue, shorter period of recovery and easy to operate. It is better than CO2 laser and Nd:YAG laser.

  13. Er:YAG laser: clinical experience based upon scientific evidence: clinical cases

    NASA Astrophysics Data System (ADS)

    Zanin, Fatima A. A.; Brugnera, Aldo, Jr.; Pecora, Jesus D.; Pinheiro, Antonio L. B.; Souza-Campos, Dilma H.; Vieira de Medeiros, Urubatan

    2001-04-01

    The aim of this work was to demonstrate, based upon scientific evidence, the efficacy of dental treatment using the Er:YAG laser. The Er:YAG laser is able of quick cavitation of dental structure with minimal thermal effect. It is also well known that most treatment is carried out without the need of local anesthesia. It is also recognized that its work with no vibration and in a non-contact mode. This paper reports the clinical results of 590 dental procedures carried out with the Er:YAG laser on selected patients. The laser was used for composite removal, cavity enamel preparation, carious dentine removal and conditioning of both dentin and enamel. Dental treatment with the Er:YAG laser as a secure and efficient method of treatment with more comfort for the patients, high acceptance form patients and less need of using local anesthesia.

  14. Up Conversion Measurements in Er:YAG; Comparison with 1.6 Micrometer Laser Performance

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Walsh, Brian M.; Amzajerdian, Farzin; Reichle, Donald J.; Busch, George E.; Carrion, William A.

    2011-01-01

    Up conversion significantly affects Er:YAG lasers. Measurements performed here for low Er concentration are significantly different than reported high Er concentration. The results obtained here are used to predict laser performance and are compared with experimental results.

  15. Erbium:YAG laser as a method of deepithelization in corrective and reductive breast surgery.

    PubMed

    Trelles, Mario A; Pardo, Lourdes; Chamorro, Juan José; Bonanad, Enrique; Allones, Inés; Buil, Carmen; Luna, Ricardo

    2005-08-01

    Deepithelization of the breast in breast ptosis surgery is important, being associated with risks which could affect the clinical outcome. The role of Er:YAG laser deepithelization was investigated. A total of 12 bilateral mammoplasties were performed, randomly assigned to 2 groups, one of experienced and one of less-experienced surgeons. Results were compared between the 2 groups of surgeons for scalpel deepithelization on one breast and the Er:YAG laser on the contralateral breast. No complications; less edema, pain, and erythema; and quicker wound healing were observed in the laser-deepithelized breasts, with a shorter operation time even for the less-experienced surgeons. The authors do not suggest that the Er:YAG laser should replace the scalpel in the hands of the expert surgeon for breast deepithelization in breast ptosis surgery, but the results of the study suggest that Er:YAG laser ablation is a safe, precise, effective and complication-free method.

  16. Optoelectronic characteristics of YAG phosphor-incorporated ZnO films deposited by ultrasonic spray pyrolysis

    PubMed Central

    2012-01-01

    This work presents a novel white light device. An yttrium aluminum garnet (YAG) phosphor-incorporated zinc oxide (ZnO) film is deposited on a slide glass substrate by ultrasonic spray pyrolysis. A nanoflower consisting of a hexagonal nanopetal is formed on the surfaces of the samples, and the sizes of the nanopetal are approximately 200 to 700 nm. Additionally, the nanopetal becomes blunted with an increasing incorporated amount of YAG. As the incorporated amount is 1.5 and 2.5 wt.%, the photoluminescence color of the YAG-incorporated ZnO film is nearly white, possibly contributing to the YAG emission and the band-to-deep level transition in the ZnO film. PMID:23151219

  17. Injection-seeded operation of a Q-switched Cr,Tm,Ho:YAG laser

    NASA Technical Reports Server (NTRS)

    Henderson, Sammy W.; Hale, Charley P.; Magee, James R.

    1991-01-01

    Single-frequency Tm,Ho:YAG lasers operating near 2 microns are attractive sources for several applications including eye-safe laser radar (lidar) and pumping of AgGaSe2 parametric oscillators for efficient generation of longer wavelengths. As part of a program to develop a coherent lidar system using Tm,Ho:YAG lasers, a diode laser-pumped tunable CW single-longitudinal-mode (SLM) Cr:Tm:Ho:YAG laser and a flashlamp-pumped single-transverse-mode Q-switched Cr,Tm,Ho:YAG laser were developed. The CW laser was used to injection-seed the flashlamp-pumped laser, resulting in SLM Q-switched output. Operational characteristics of the CW and Q-switched lasers and injection-seeding results are reported.

  18. Injection-seeded operation of a Q-switched Cr,Tm,Ho:YAG laser

    NASA Technical Reports Server (NTRS)

    Henderson, Sammy W.; Hale, Charley P.; Magee, James R.

    1991-01-01

    Single-frequency Tm,Ho:YAG lasers operating near 2 microns are attractive sources for several applications including eye-safe laser radar (lidar) and pumping of AgGaSe2 parametric oscillators for efficient generation of longer wavelengths. As part of a program to develop a coherent lidar system using Tm,Ho:YAG lasers, a diode laser-pumped tunable CW single-longitudinal-mode (SLM) Cr:Tm:Ho:YAG laser and a flashlamp-pumped single-transverse-mode Q-switched Cr,Tm,Ho:YAG laser were developed. The CW laser was used to injection-seed the flashlamp-pumped laser, resulting in SLM Q-switched output. Operational characteristics of the CW and Q-switched lasers and injection-seeding results are reported.

  19. Up Conversion Measurements in Er:YAG; Comparison with 1.6 Micrometer Laser Performance

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Walsh, Brian M.; Amzajerdian, Farzin; Reichle, Donald J.; Busch, George E.; Carrion, William A.

    2011-01-01

    Up conversion significantly affects Er:YAG lasers. Measurements performed here for low Er concentration are significantly different than reported high Er concentration. The results obtained here are used to predict laser performance and are compared with experimental results.

  20. Use of the Q-switch Nd:YAG laser in the treatment of cataracts

    NASA Astrophysics Data System (ADS)

    Kecik, Dariusz

    1997-10-01

    The most frequent uses of the Nd:YAG laser in the surgical treatment for cataract are presented. Preoperative, intraoperative and postoperative applications are discussed together with the most frequency complications.

  1. Endolenticular phacolysis using the erbium:YAG laser on human autopsy lenses: a histopathologic study

    NASA Astrophysics Data System (ADS)

    Noecker, Robert J.; Kramer, Theresa R.; Ellsworth, Lansing G.; Snyder, Robert W.; Yarborough, J. Michael

    1994-06-01

    A pulsed erbium:YAG laser equipped with a 1-m zirconium fluoride fiber coupled with a sapphire tip was used to photovaporize human autopsy lens tissue. Measured diameter of photovaporization of human lens cortex with erbium:YAG laser ranged from 117 micrometers at a fluence of 3.98 J/cm2 to 227 micrometers at fluence of 15.92 J/cm2. Measured diameter of photovaporization of human lens nucleus with Erbium:YAG laser ranged from 265 micrometers at a fluence of 11 J/cm2 and 295 micrometers at a fluence of 15 J/cm2. Endolenticular phacovaporization with the Erbium:YAG laser appears to be a potentially efficient and precise means of removing the human lens.

  2. An energy adjustable linearly polarized passively Q-switched bulk laser with a wedged diffusion-bonded Nd:YAG/Cr⁴⁺:YAG crystal.

    PubMed

    Cho, C Y; Cheng, H P; Chang, Y C; Tang, C Y; Chen, Y F

    2015-03-23

    An energy adjustable passively Q-switched laser is demonstrated with a composite Nd:YAG/Cr⁴⁺:YAG crystal by applying a wedged interface inside the crystal. The theoretical model of the monolithic laser resonator is explored to show the energy adjustable feature with different initial transmissions of the saturable absorber at the horizontal axis. By adjusting the pump beam location across the Nd:YAG crystal, the output pulse energy can be flexibly changed from 10.9 μJ to 17.6 μJ while maintaining the same output efficiency. The polarization state of the laser output is found to be along with the polarization of the C-mount pump diode. Finally, the behavior of the multi-transverse-mode oscillation is also discussed for eliminating the instability of the pulse train.

  3. Holographic interferometry with an injection seeded Nd:YAG laser and two reference beams

    NASA Technical Reports Server (NTRS)

    Decker, Arthur J.

    1989-01-01

    The performance of twin injection seeded Nd:YAG lasers is compared with the performance of an argon-ion laser for recording dual-reference-beam holograms in AGFA 8E56 emulsion. Optical heterodyning is used to measure interference, and the results are expressed in terms of heterodyning signal level and intensity signal-to-noise. The Nd:YAG laser system is to be used for optical inspections of structures for cracks, defects, gas leaks, and structural changes.

  4. The growth of Ho:YAG single crystals by Czochralski method and investigating the formed cores

    SciTech Connect

    Hasani Barbaran, J. Ghani Aragi, M. R.; Javaheri, I.; Baharvand, B.; Tabasi, M.; Layegh Ahan, R.; Jangjo, E.

    2015-12-15

    Ho:YAG single crystals were grown by Czochralski technique, and investigated by the X-ray diffraction (XRD) and optical methods. The crystals were cut and polished in order to observe and analyze their cores. It was found that the deviation of the cores formed in the Czochralski grown Ho:YAG single crystals are resulted from non-symmetrical status of thermal insulation around the Iridium crucible.

  5. Effect of CW YAG and argon green lasers on experimentally detached retinas.

    PubMed

    Peyman, G A; Conway, M D; House, B J

    1984-06-01

    We evaluated the effects of argon-green (514.5 nm) and CW neodymium YAG (1060 nm) wavelengths on experimentally detached retinas of primates. Neither laser produced damage to the sensory retina of the fovea. The argon green wavelength, which was absorbed by haemoglobin in the vessel or by extravasated red blood cells, created vasospasm and nerve fiber layer damage. The beam of the CW YAG was not absorbed by haemoglobin; therefore, no vasospasm could be produced on experimentally detached retinas.

  6. Monostatic Doppler lidar using an Nd:YAG laser for wind-velocity measurement

    NASA Astrophysics Data System (ADS)

    Bersenev, V. I.; Kaptsov, L. N.; Priezzhev, A. V.

    1987-10-01

    A monostatic Doppler lidar using a CW Nd:YAG laser has been developed for measurements of wind velocity. A series of atmospheric measurements using this lidar was carried out. At medium turbulence levels, the limiting lidar range is 200 m. As compared with a CO2 Doppler lidar, the Nd:YAG lidar has a better spatial resolution, is more convenient to use, and does not require a cooled photodetector.

  7. Z-scan Measurement of the Upconversion Coefficient in Er:YAG

    DTIC Science & Technology

    2009-09-01

    technique for measuring the upconversion coefficient that uses the same continuous wave (CW) source that is used to pump an Er:YAG laser . We find that...The schematic for the experimental setup is shown in figure 2. A 5-MHz linewidth distributed feedback Bragg (DFB) laser diode is temperature tuned...Conclusions In an Er:YAG laser operating at 1645 nm, no upconversion would ideally take place, and the pump photons would have a 1:1 ratio with emitted

  8. Er:YAG laser for the surgical treatment of the carpal tunnel syndrome

    NASA Astrophysics Data System (ADS)

    Russ, Detlef; Ebinger, Thomas; Illich, Wolfgang; Steiner, Rudolf W.

    2003-10-01

    We developed a new surgical procedure to improve the recurrence rate using an Er:YAG laser as dissection tool for the carpal ligament with the objective to ablate a small amount of the carpal ligament and to denaturate its ends. The Er:YAG Laser was transmitted to the applicator via a GeO fiber. With this system we proceeded 10 carpal ligament dissections without any complications in the follow-up period. All patients were free of pain and recurrence.

  9. Holographic interferometry with an injection seeded Nd:YAG laser and two reference beams

    NASA Technical Reports Server (NTRS)

    Decker, Arthur J.

    1990-01-01

    The performance of twin injection seeded Nd:YAG lasers is compared with the performance of an argon-ion laser for recording dual-reference-beam holograms in AGFA 8E56 emulsion. Optical heterodyning is used to measure interference, and the results are expressed in terms of heterodyning signal level and intensity signal-to-noise. The Nd:YAG laser system is to be used for optical inspections of structures for cracks, defects, gas leaks, and structural changes.

  10. Q-switched pulse laser generation from double-cladding Nd:YAG ceramics waveguides.

    PubMed

    Tan, Yang; Luan, Qingfang; Liu, Fengqin; Chen, Feng; Vázquez de Aldana, Javier Rodríguez

    2013-08-12

    This work reports on the Q-switched pulsed laser generation from double-cladding Nd:YAG ceramic waveguides. Double-cladding waveguides with different combination of diameters were inscribed into a sample of Nd:YAG ceramic. With an additional semiconductor saturable absorber, stable pulsed laser emission at the wavelength of 1064 nm was achieved with pulses of 21 ns temporal duration and ~14 μJ pulse energy at a repetition rate of 3.65 MHz.

  11. Cystoscopic suture removal by Holmium-YAG laser after Burch procedure.

    PubMed

    Karaşahin, Emre Kazım; Esin, Sertaç; Alanbay, Ibrahim; Ercan, Mutlu Cihangir; Mutlu, Erol; Başer, Iskender; Basal, Seref

    2011-01-01

    Burch colposuspension remains one of the successful operations performed for stress incontinence. Accidental suturing of the bladder wall during the procedure or subsequent erosion may lead to lower urinary tract symptoms. Diagnosis and management of these sutures indicate precise evaluation for which a 70 degree cystoscope is used. In selected cases, Holmium-YAG laser may enable us to manage long-standing, encrustated neglected sutures. Here we would like to report successful removal of intravesical sutures using the Holmium-YAG laser.

  12. Holmium:YAG laser-assisted otolaryngologic surgery: Lahey Clinic experience

    NASA Astrophysics Data System (ADS)

    Shapshay, Stanley M.; Rebeiz, Elie E.; Pankratov, Michail M.

    1993-07-01

    The Holmium:YAG laser was used to assist in 36 rhinologic procedures including surgery for chronic sinus disease, chronic dacryocystitis, recurrent choanal stenosis, and a sphenoid sinus mucocele. There were no laser related complications. The laser permitted controlled ablation of bone and soft tissue in all cases with satisfactory results. The Ho:YAG laser can be used in otolaryngology to assist in cases where surgical access is difficult or when controlled, precise bone and soft tissue ablation is necessary.

  13. Features of YAG crystal growth under Ar+CO reducing atmosphere

    NASA Astrophysics Data System (ADS)

    Arhipov, P.; Tkachenko, S.; Vasiukov, S.; Hubenko, K.; Gerasymov, Ia.; Baumer, V.; Puzan, A.; Mateychenko, P.; Lebbou, K.; Sidletskiy, O.

    2016-09-01

    The influence of the reducing Ar+CO atmosphere on the stages of starting raw material preparation, growth and post-growth annealing of yttrium aluminum garnet, Y3Al5O12 (YAG) crystals was studied. The chemical reactions involving CO atmosphere and its impact on the raw material, melt, and crystal composition are determined. Modification of YAG optical properties under the reducing annealing is discussed.

  14. Amorphous-crystalline transition in thermoelectric NbO2

    NASA Astrophysics Data System (ADS)

    Music, Denis; Chen, Yen-Ting; Bliem, Pascal; Geyer, Richard W.

    2015-06-01

    Density functional theory was employed to design enhanced amorphous NbO2 thermoelectrics. The covalent-ionic nature of Nb-O bonding is identical in amorphous NbO2 and its crystalline counterpart. However, the Anderson localisation occurs in amorphous NbO2, which may affect the transport properties. We calculate a multifold increase in the absolute Seebeck coefficient for the amorphous state. These predictions were critically appraised by measuring the Seebeck coefficient of sputtered amorphous and crystalline NbO2 thin films with the identical short-range order. The first-order phase transition occurs at approximately 550 °C, but amorphous NbO2 possesses enhanced transport properties at all temperatures. Amorphous NbO2, reaching  -173 μV K-1, exhibits up to a 29% larger absolute Seebeck coefficient value, thereby validating the predictions.

  15. The Structure and Properties of Amorphous Indium Oxide

    PubMed Central

    2015-01-01

    A series of In2O3 thin films, ranging from X-ray diffraction amorphous to highly crystalline, were grown on amorphous silica substrates using pulsed laser deposition by varying the film growth temperature. The amorphous-to-crystalline transition and the structure of amorphous In2O3 were investigated by grazing angle X-ray diffraction (GIXRD), Hall transport measurement, high resolution transmission electron microscopy (HRTEM), electron diffraction, extended X-ray absorption fine structure (EXAFS), and ab initio molecular dynamics (MD) liquid-quench simulation. On the basis of excellent agreement between the EXAFS and MD results, a model of the amorphous oxide structure as a network of InOx polyhedra was constructed. Mechanisms for the transport properties observed in the crystalline, amorphous-to-crystalline, and amorphous deposition regions are presented, highlighting a unique structure–property relationship. PMID:25678743

  16. Atomic-scale disproportionation in amorphous silicon monoxide

    PubMed Central

    Hirata, Akihiko; Kohara, Shinji; Asada, Toshihiro; Arao, Masazumi; Yogi, Chihiro; Imai, Hideto; Tan, Yongwen; Fujita, Takeshi; Chen, Mingwei

    2016-01-01

    Solid silicon monoxide is an amorphous material which has been commercialized for many functional applications. However, the amorphous structure of silicon monoxide is a long-standing question because of the uncommon valence state of silicon in the oxide. It has been deduced that amorphous silicon monoxide undergoes an unusual disproportionation by forming silicon- and silicon-dioxide-like regions. Nevertheless, the direct experimental observation is still missing. Here we report the amorphous structure characterized by angstrom-beam electron diffraction, supplemented by synchrotron X-ray scattering and computer simulations. In addition to the theoretically predicted amorphous silicon and silicon-dioxide clusters, suboxide-type tetrahedral coordinates are detected by angstrom-beam electron diffraction at silicon/silicon-dioxide interfaces, which provides compelling experimental evidence on the atomic-scale disproportionation of amorphous silicon monoxide. Eventually we develop a heterostructure model of the disproportionated silicon monoxide which well explains the distinctive structure and properties of the amorphous material. PMID:27172815

  17. Atomic-scale disproportionation in amorphous silicon monoxide.

    PubMed

    Hirata, Akihiko; Kohara, Shinji; Asada, Toshihiro; Arao, Masazumi; Yogi, Chihiro; Imai, Hideto; Tan, Yongwen; Fujita, Takeshi; Chen, Mingwei

    2016-05-13

    Solid silicon monoxide is an amorphous material which has been commercialized for many functional applications. However, the amorphous structure of silicon monoxide is a long-standing question because of the uncommon valence state of silicon in the oxide. It has been deduced that amorphous silicon monoxide undergoes an unusual disproportionation by forming silicon- and silicon-dioxide-like regions. Nevertheless, the direct experimental observation is still missing. Here we report the amorphous structure characterized by angstrom-beam electron diffraction, supplemented by synchrotron X-ray scattering and computer simulations. In addition to the theoretically predicted amorphous silicon and silicon-dioxide clusters, suboxide-type tetrahedral coordinates are detected by angstrom-beam electron diffraction at silicon/silicon-dioxide interfaces, which provides compelling experimental evidence on the atomic-scale disproportionation of amorphous silicon monoxide. Eventually we develop a heterostructure model of the disproportionated silicon monoxide which well explains the distinctive structure and properties of the amorphous material.

  18. Combined application of Er:YAG and Nd:YAG lasers in treatment of chronic periodontitis. A split-mouth, single-blind, randomized controlled trial.

    PubMed

    Sağlam, M; Köseoğlu, S; Taşdemir, I; Erbak Yılmaz, H; Savran, L; Sütçü, R

    2017-10-01

    The aim of the present study was to compare the effectiveness of combined Er:YAG and Nd:YAG laser therapy to that of scaling and root planing with hand instruments in non-surgical treatment of chronic periodontitis. Twenty-five systemically healthy patients with chronic periodontitis were selected for this study. The quadrants were randomly allocated in a split-mouth design to either combined Er:YAG (160 mJ/pulse, 10 Hz) and Nd:YAG laser (100 mJ/pulse, 20 Hz) therapy (test group) or scaling and root planing alone (control group). At baseline, 1 month and 3 months after treatment, plaque index, gingival index, probing depth, clinical attachment level and bleeding on probing (%), were recorded and gingival crevicular fluid and subgingival plaque samples were taken. The gingival crevicular fluid levels of interleukin-1β and tumor necrosis factor-α were analyzed by enzyme-linked immunosorbent assay. Quantitative analysis of red complex bacteria was performed using quantitative real-time polymerase chain reaction. The clinical parameters had significantly improved for both groups after treatment. There were statistically significant differences in probing depth and clinical attachment level between the test and control groups only for deep pockets (≥7 mm) (P<.05). No significant differences between the two groups were observed for the biochemical and microbiological parameters at any time points (P>.05). The present study suggests that a combined course of Er:YAG and Nd:YAG laser therapy may be beneficial particularly in inaccessible areas such as deep pockets on a short-term basis. Further, well-designed studies are required to assess the effectiveness of the combination of these lasers. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. Combination of CO2 and Q-switched Nd:YAG lasers is more effective than Q-switched Nd:YAG laser alone for eyebrow tattoo removal.

    PubMed

    Radmanesh, Mohammad; Rafiei, Zohreh

    2015-04-01

    The eyebrow tattoo removal using Q-switched lasers is usually prolonged. Other modalities may be required to enhance the efficacy and shorten the treatment course. To compare the efficacy of Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser alone versus combination of Q-switched Nd:YAG and Ultrapulse CO2 lasers for eyebrow tattoo removal after a single session. After local anesthesia, the right eyebrow of 20 patients was treated with Ultrapulse CO2 laser with the parameters of 4 J/cm(2) and 3.2 J/cm(2) for the first and the second passes. Both eyebrows were then treated with 1064-nm and 532-nm Q-switched Nd:YAG laser. The spot size and pulse duration were 3 mm and 5 nanoseconds for both wavelengths, and the fluence was 7 J/cm(2) for 1064 nm and 3 J/cm (2) for 532 nm. The side treated with combination of Q-switched Nd:YAG and CO2 lasers improved 75-100% in 6 of 20 patients versus only 1 of 20 in the side treated with Q-switched Nd:YAG alone. Similarly, the right side in 13 of 20 patients showed more than 50% improvement with combination therapy versus the left side (the monotherapy side), where only 6 of 20 cases showed more than 50% improvement. The Mann-Whitney test was 2.85 for the right side and 1.95 for the left side (P value = 0.007). Using Ultra pulse CO2 laser enhances the efficacy of Q-switched Nd:YAG laser in eyebrow tattoo removal.

  20. Scanning electron microscopy (SEM) and optical microscopy: effects of Er:YAG and Nd:YAG lasers on apical seals after apicoectomy and retrofill.

    PubMed

    Oliveira, R G; Gouw-Soares, S; Baldochi, S L; Eduardo, C P

    2004-12-01

    This study evaluated the dentinal and marginal permeability of the cut surface after apicoectomy, treatment and retrocavity preparation with Er:YAG and Nd:YAG lasers. Furthermore, scanning electron microscopy (SEM) analysed the morphological alteration of dentin caused by laser irradiation through an optical fiber. Numerous studies have shown the beneficial effects of laser treatment upon sealing dental apex, avoiding the changes of organic fluids, microorganisms and their by-products between the root canal system and periapex. Twenty-four extracted and endodontically treated teeth were divided into three groups: GI, apices were resected with Er:YAG laser (350 mJ; 4 Hz) treatment of cut dentinal surface and retrocavity were lased with this same laser (120 mJ; 4 Hz; bur 2051) using the optical fiber 50/10; GII, apicoectomy was performed similar to GI, however the cut dentinal surface was treated with Nd:YAG laser through optical fiber, as well as the retrocavity preparation (100 mJ; 15 Hz; 1.5 W); and GIII (control group), high speed burs were used. Analysis of methylene blue dye penetration into dentin demonstrated that the specimens of the groups irradiated with laser showed to have lower infiltration indices than the control group. These results were compatible with structural and morphological injuries, evidenced by SEM. Under the conditions of the present study, apicoectomy using Er:YAG laser, followed by dentinal surface irradiation and retrocavity preparation with Nd:YAG laser, showed to be an alternative clinical tool able to reduce the dentinal permeability.

  1. Wound healing and soft tissue effects of CO2, contact Nd: YAG and combined CO2-Nd: YAG laser beams on rabbit trachea.

    PubMed

    Laranne, J; Lagerstedt, A; Pukander, J; Rantala, I

    1997-11-01

    Rabbit trachea was used as an experimental model to study tissue effects and healing of full-thickness tracheal lesions produced by CO2, contact Nd: YAG and combined, coaxial CO2-Nd: YAG (Combo) laser beams. Two power settings (10 W and 16 W) were used with CO2 and contact Nd: YAG lasers. Three different CO2/Nd:YAG power ratios (1:1, 1:2 and 1:4) and power settings (12 W 15 W and 16 W) were used with the Combolaser. Histological specimens for light and transmission electron microscopy were prepared immediately and 1, 3, 5, 7, 14 and 21 days postoperatively. The wound with the most precise and fastest healing was produced by contact Nd: YAG laser. CO2 laser produced a moderate amount of charring and the largest amount of coagulated tissue with a slightly prolonged healing period. In the acute phase, tissue defects produced by the Combolaser with power ratios 1:1 and 1:2 resembled the CO2 laser lesions but with slightly less charring. The power ratio 1:4 diminished the cutting properties of the beam considerably. During the healing period the Combolaser produced the most intensive inflammation and granulation tissue formation resulting in delayed regeneration of the lesion. In transmission electron micrographs the most severe damage to chondrocytes was seen after using the Combolaser. These findings indicate that the Combolaser produces deeper tissue damage than CO2 or contact Nd:YAG laser. However, the Combolaser appears to be suitable for tracheobronchial operations, owing to its good simultaneous cutting and haemostatic properties.

  2. Comparative study between Fortify and Nd:YAG laser used for marginal sealing in composite restorations

    NASA Astrophysics Data System (ADS)

    Navarro, Ricardo S.; Esteves, Grazia V.; Oliveira, Wilson T., Jr.; Matos, Adriana B.; Turbino, Mirian L.; Youssef, Michel N.; Matson, Edmir

    1999-05-01

    The aim of this study was to evaluate microleakage of composite restorations submitted to marginal treatment. Class V preparations with walls located in enamel were performed at buccal and lingual surfaces of eighteen recently extracted, non-carious human premolars. Cavities were restored with composite resins and adhesive system. Samples were stored in distilled water for 48h and polished with Sof-Lex discs. Teeth were randomly divide in six groups: G1 - Control; G2 - marginal treatment with surface sealant; G3 - Nd:YAG 25 Hz, 80mJ, 2W; G4 - Nd:YAG 20Hz, 100mJ, 2W; G5 - Nd:YAG 30Hz, 60mJ, 1.8W; G6 - Nd:YAG 30Hz, 40mJ, 1.2W. Contact fiberoptic (300μm) pulsed (1.064 μm) Nd:YAG laser was used for 30sec, under air cooling. Teeth were impermeabilized, immersed in a dye (Rhodamine B) for 4h at 37°, and sectioned. Specimens were evaluated under light microscopy and evaluated with scores. Results were analyzed with Kruskal- Wallis test (p=0.05) and showed that there were significant differences between marginal treatments; there were no significant differences beaten groups 1, 2, 4 and 3, 5, 6; lower values of microleakage were at groups 3, 5, 6. Nd:YAG laser showed marginal sealing ability and decreased microleakage of composite resins restorations.

  3. Laser-assisted hair transplantation: histologic comparison between holmium:YAG and CO2 lasers

    NASA Astrophysics Data System (ADS)

    Chu, Eugene A.; Rabinov, C. Rose; Wong, Brian J.; Krugman, Mark E.

    1999-06-01

    The histological effects of flash-scanned CO2 (λ=10.6μm) and pulsed Holmium:YAG (Ho:YAG, λ=2.12μm) lasers were evaluated in human scalp following the creation of hair transplant recipient channels. Ho:YAG laser irradiation created larger zones of thermal injury adjacent to the laser channels than irradiation with the CO2 laser device. When the two lasers created recipient sites of nearly equal depth, the Holmium:YAG laser caused a larger region of lateral thermal damage (589.30μm) than the CO2 laser (118.07μm). In addition, Holmium:YAG irradiated specimens exhibited fractures or discontinuities beyond the region of clear thermal injury. This shearing effect is consistent with the photoacoustic mechanism of ablation associated with pulsed mid-IR laser irradiation. In contrast, channels created with the CO2 exhibited minimal epithelial disruption and significantly less lateral thermal damage. While the Holmium:YAG laser is a useful tool for ablation soft tissue with minimal char in select applications (sinus surgery, arthroscopic surgery), this study suggests that the use of the CO2 laser for the creation of transplantation recipient channels result in significantly less lateral thermal injury for the laser parameters employed.

  4. Comparison of spectroscopic properties of Tm and Ho in YAG and YLF crystals

    NASA Technical Reports Server (NTRS)

    Armagan, G.; Buoncristiani, A. M.; Inge, A. T.; Di Bartolo, B.

    1991-01-01

    The paper compares the cross-relaxation, energy transfer and loss processes in Tm- and Ho-doped YAG and YLF as a function of temperature, Tm concentration, and excitation power. Significant differences in the behavior of Tm and Tm,Ho in YAG and YLF crystals were found. The cross-relaxation rates of Tm(6 pct) are faster in YLF (about 5 microsec) than YAG (about 10 microsec). The energy transfer rates between Tm and Ho are faster in YLF than YAG. The time it takes for the maximum intensity of 1.7-micron emission to drop 10 percent is 25 microsec for YLF:Tm(6 pct),Ho(0.6 pct) and 65 microsec YAG:Tm(6 pct),Ho(0.5 pct). The losses occurring with increasing pump power for 2.1-micron emission of the above samples are 30 percent less in YLF than YAG. These qualitative differences point to YLF as a valuable 2-micron laser host material.

  5. Er:YAG laser irradiation to control the progression of enamel erosion: an in situ study.

    PubMed

    Scatolin, R S; Colucci, V; Lepri, T P; Alexandria, A K; Maia, L C; Galo, R; Borsatto, M C; Corona, S A M

    2015-07-01

    This in situ study evaluated the effect of Er:YAG laser irradiation in controlling the progression of enamel erosion-like lesions. Fifty-six enamel slabs (330 KHN ± 10 %) with one fourth of the surface covered with resin composite (control area) were submitted to initial erosion-like lesion formation with citric acid. The slabs were divided into two groups: irradiated with Er:YAG laser and non-irradiated. Fourteen volunteers used an intraoral palatal appliance containing two slabs, in two phases of 5 days each. During the intraoral phase, in a crossed-over design, half of the volunteers immersed the appliance in citric acid while the other half used deionized water, both for 5 min, three times per day. Enamel wear was determined by an optical 3D profilometer. ANOVA revealed that when deionized water was used as immersion solution during the intraoral phase, lower values of wear were showed when compared with the groups that were eroded with citric acid, whether irradiated or non-irradiated with Er:YAG laser. When erosion with citric acid was performed, Er:YAG laser was not able to reduce enamel wear. Small changes on enamel surface were observed when it was irradiated with Er:YAG laser. It may be concluded that Er:YAG laser irradiation did not reduce the progression of erosive lesions on enamel submitted to in situ erosion with citric acid.

  6. Er:YAG Laser Dental Treatment of Patients Affected by Epidermolysis Bullosa

    PubMed Central

    Galeotti, Angela; D'Antò, Vincenzo; Gentile, Tina; Giancristoforo, Simona; Romeo, Umberto

    2014-01-01

    Aim. The purpose of this study was to evaluate the efficacy of Er:YAG laser used for treating hard dental tissue in patients with epidermolysis bullosa (EB). Methods. We report two cases of EB in which an Er:YAG laser was used for conservative treatments. In the first case, the Er:YAG laser (2,940 μm, 265 mJ, 25 Hz) was used to treat caries on a deciduous maxillary canine in an 8-year-old male patient affected by dystrophic EB. In the second case, we treated a 26-year-old female patient, affected by junctional EB, with generalized enamel hypoplasia, and an Er:YAG laser (2,940 μm, 265 mJ, 25 Hz) was used to remove the damaged enamel on maxillary incisors. Results. The use of the Er:YAG laser, with the appropriate energy, was effective in the selective removal of carious tissue and enamel hypoplasia. During dental treatment with the Er:YAG laser, patients required only a few interruptions due to the absence of pain, vibration, and noise. Conclusions. Laser treatment of hard dental tissues is a valuable choice for patients affected by EB since it is less invasive compared to conventional treatment, resulting in improved patient compliance. PMID:25431688

  7. Comparison of spectroscopic properties of Tm and Ho in YAG and YLF crystals

    NASA Technical Reports Server (NTRS)

    Armagan, G.; Buoncristiani, A. M.; Inge, A. T.; Di Bartolo, B.

    1991-01-01

    The paper compares the cross-relaxation, energy transfer and loss processes in Tm- and Ho-doped YAG and YLF as a function of temperature, Tm concentration, and excitation power. Significant differences in the behavior of Tm and Tm,Ho in YAG and YLF crystals were found. The cross-relaxation rates of Tm(6 pct) are faster in YLF (about 5 microsec) than YAG (about 10 microsec). The energy transfer rates between Tm and Ho are faster in YLF than YAG. The time it takes for the maximum intensity of 1.7-micron emission to drop 10 percent is 25 microsec for YLF:Tm(6 pct),Ho(0.6 pct) and 65 microsec YAG:Tm(6 pct),Ho(0.5 pct). The losses occurring with increasing pump power for 2.1-micron emission of the above samples are 30 percent less in YLF than YAG. These qualitative differences point to YLF as a valuable 2-micron laser host material.

  8. YAG:Ce nano-sized phosphor particles prepared by a solvothermal method

    SciTech Connect

    Li Xia; Liu Hong; Wang Jiyang; Cui Hongmei; Han Feng

    2004-10-04

    Nano-sized Ce-doped YAG phosphor particles were synthesized by a mixed solvothermal method using the stoichiometric amounts of inorganic aluminum and yttrium salts. The formation of YAG:Ce was investigated by means of XRD and TG-DTA. The purified YAG crystalline phases was obtained under moderate synthesis condition (300 deg. C and 10 MPa), this indicated that ethanol replaced part of water as solvent favoring the formation of YAG. TEM images showed that YAG:Ce phosphor particles were basically spherical in shape, well dispersed and a mean grain size about 60 nm. The particle absorbed excitation energy in the range 403-510 nm, and the maximum excitation wavelength was near 470 nm. The crystalline YAG:Ce showed broad emission peaks in the range 480-650 nm and had maximum intensity at 528 nm. The excitation and emission intensity increased with increasing the synthesis temperature from 280 to 300 deg. C, and get the maximum brightness at 300 deg. C.

  9. 10-kW-class YAG laser application for heavy components

    NASA Astrophysics Data System (ADS)

    Ishide, Takashi; Tsubota, S.; Nayama, Michisuke; Shimokusu, Yoshiaki; Nagashima, Tadashi; Okimura, K.

    2000-02-01

    The authors have put the YAG laser of the kW class to practical use for repair welding of nuclear power plant steam generator heat exchanger tubes, all-position welding of pipings, etc. This paper describes following developed methods and systems of high power YAG laser processing. First, we apply the 6 kW to 10 kW YAG lasers for welding and cutting in heavy components. The beam guide systems we have used are optical fibers which core diameter is 0.6 mm to 0.8 mm and its length is 200 m as standard one. Using these system, we can get the 1 pass penetration of 15 mm to 20 mm and multi pass welding for more thick plates. Cutting of 100 mm thickness plate data also described for dismantling of nuclear power plants. In these systems we carried out the in-process monitoring by using CCD camera image processing and monitoring fiber which placed coaxial to the YAG optical lens system. In- process monitoring by the monitoring fiber, we measured the light intensity from welding area. Further, we have developed new hybrid welding with the TIG electrode at the center of lens for high power. The hybrid welding with TIG-YAG system aims lightening of welding groove allowances and welding of high quality. Through these techniques we have applied 7 kW class YAG laser for welding in the components of nuclear power plants.

  10. Novel microwave assisted synthesis of highly doped phase pure Nd:YAG nanopowder

    NASA Astrophysics Data System (ADS)

    Kiranmala, L.; Rekha, M.; Neelam, M.

    2011-09-01

    For the first time, the studies on 2 to 10 at.% neodymium (Nd3+) ion doped Yttrium Aluminum Garnet (Nd:YAG) nanopowders obtained by microwave assisted citrate nitrate gel combustion synthesis is described in this work. This paper reports on high doping of Nd3+ ions with retaining the cubic garnet structure of YAG as evidenced from XRD, except the case of 8 at.% doped Nd:YAG. Phase pure YAG formation with 8 at.% Nd3+ doping was explored by using urea and alanine as alternative to citric acid complexing agents. Complete crystallization of YAG as a result of 2 hour thermal treatment at 900 °C under oxygen supply was studied by using Fourier Transform Infra-Red Spectroscopy (FTIR) and X-Ray Diffraction (XRD) techniques. With an increase in the dopant concentration a red shift in the FTIR peaks was observed. Using the XRD data, the cell parameter of Nd3+ (2 to 6 and 10 at.%) YAG was found to increase with an increase in the dopant concentration. The average primary particle size calculated using Scherrer's equation was ˜25 nm which was additionally supported by Transmission Electron Microscopy (TEM) results yielding particle sizes in the range of ˜25 to 30 nm for all the cases.

  11. Peculiarities of luminescent and scintillation properties of YAG:Ce phosphor prepared in different crystalline forms

    NASA Astrophysics Data System (ADS)

    Zorenko, Y.; Zorenko, T.; Gorbenko, V. V.; Voznyak, T.; Savchyn, V.; Bilski, P.; Twardak, A.

    2012-06-01

    In this work, we have performed the comparative analysis of the luminescent and scintillation properties of Y3Al5O12:Ce (YAG:Ce) single crystals (SC), single crystalline films (SCF) and transparent optical ceramics (OС) using the traditional spectral methods as well as the luminescence spectroscopy under excitation by pulsed synchrotron radiation in the fundamental absorption range of YAG host. We have shown that the properties of YAG:Ce OC are rather closer to the properties of SCF counterpart where YAl antisite defects are completely absent than to the properties of SC of this garnet with large concentration of YAl antisite defects. At the same time, the luminescence spectra of YAG:Ce OC and SC show the emission bands in the 200-450 nm range related to YAl antisite defects and charged oxygen vacancies (F+ and F-centers). YAG:Ce ОС also possesses significantly higher thermoluminescence in the range above room temperature and large contribution of slow components in the Ce3+ luminescence decay under high-energy excitation in comparison with SC and SCF of this garnet. The mentioned properties of YAG:Ce OC are caused by the participation of antisite defects and charged oxygen vacancies located in OC mainly on the boundaries of grains, as trapping centers in the energy transfer processes from the host to the Ce3+ ions.

  12. [Usefulness of ND:YAG laser in head and neck surgery].

    PubMed

    Stankiewicz, Czesław; Kowalska, Bozena

    2004-01-01

    Nd:YAG laser is widely used in surgery as well as in otolaryngology and head and neck surgery for 25 years. This type of laser is characterized by low absorption in water and haemoglobin, deep penetration to the tissue and high ability for vessels coagulation. The laser light can be guided with glassfiber and can be focussed with handpices and micromanipulators. These characteristics make Nd:YAG laser very useful surgical instrument, especially in ORL and head and neck surgery. One institution's experiences, based on 300 operations with Nd:YAG laser are presented and discussed. Main indications to Nd:YAG laser operations in our material were: malignant neoplasms of oral cavity, pharynx and larynx, papillomas and haemangiomas of mucosa of upper respiratory tract, tracheal stenoses, scars of the larynx after partial laryngectomies and snoring and sleep apnoea syndrome. In our opinion, Nd:YAG laser has high usefulness in treatment of malignant and benign head and neck neoplasms, as well as in laryngeal scars and treatment of snoring. In cases of post intubation tracheal stenoses and in cases of post strumectomy bilateral paralysis of larynx the treatment results were not satisfactory. High usefulness of Nd:YAG laser results from very good coagulation ability and wide possibility of transmission of laser light with glassfiber.

  13. Disappearance and Creation of Constrained Amorphous Phase

    NASA Astrophysics Data System (ADS)

    Cebe, Peggy; Lu, Sharon X.

    1997-03-01

    We report observation of the disappearance and recreation of rigid, or constrained, amorphous phase by sequential thermal annealing. Tempera- ture modulated differential scanning calorimetry (MDSC) is used to study the glass transition and lower melting endotherm after annealing. Cold crystallization of poly(phenylene sulfide), PPS, at a temperature just above Tg creates an initial large fraction of rigid amorphous phase (RAP). Brief, rapid annealing to a higher temperature causes RAP almost to disappear completely. Subsequent reannealing at the original lower temperature restores RAP to its original value. At the same time that RAP is being removed, Tg decreases; when RAP is restored, Tg also returns to its initial value. The crystal fraction remains unaffected by the annealing sequence.

  14. Annealing behavior of high permeability amorphous alloys

    SciTech Connect

    Rabenberg, L.

    1980-06-01

    Effects of low temperature annealing on the magnetic properties of the amorphous alloy Co/sub 71/ /sub 4/Fe/sub 4/ /sub 6/Si/sub 9/ /sub 6/B/sub 14/ /sub 4/ were investigated. Annealing this alloy below 400/sup 0/C results in magnetic hardening; annealing above 400/sup 0/C but below the crystallization temperature results in magnetic softening. Above the crystallization temperature the alloy hardens drastically and irreversibly. Conventional and high resolution transmission electron microscopy were used to show that the magnetic property changes at low temperatures occur while the alloy is truly amorphous. By imaging the magnetic microstructures, Lorentz electron microscopy has been able to detect the presence of microscopic inhomogeneities in this alloy. The low temperature annealing behavior of this alloy has been explained in terms of atomic pair ordering in the presence of the internal molecular field. Lorentz electron microscopy has been used to confirm this explanation.

  15. Wear Resistant Amorphous and Nanocomposite Coatings

    SciTech Connect

    Racek, O

    2008-03-26

    Glass forming materials (critical cooling rate <10{sup 4}K.s{sup -1}) are promising for their high corrosion and wear resistance. During rapid cooling, the materials form an amorphous structure that transforms to nanocrystalline during a process of devitrification. High hardness (HV 1690) can be achieved through a controlled crystallization. Thermal spray process has been used to apply coatings, which preserves the amorphous/nanocomposite structure due to a high cooling rate of the feedstock particles during the impact on a substrate. Wear properties have been studied with respect to process conditions and feedstock material properties. Application specific properties such as sliding wear resistance have been correlated with laboratory tests based on instrumented indentation and scratch tests.

  16. Structural characterization of stable amorphous silicon films

    NASA Astrophysics Data System (ADS)

    Zhang, Shibin; Kong, Guanglin; Wang, Yongqian; Sheng, Shuran; Liao, Xianbo

    2002-05-01

    A kind of hydrogenated diphasic silicon films has been prepared by a new regime of plasma enhanced chemical vapor deposition (PECVD) in the region adjacent to the phase transition from amorphous to crystalline state. The photoelectronic and microstructural properties of the films have been investigated by the constant photocurrent method (CPM), Raman scattering and nuclear magnetic resonance (NMR). Our experimental results and corresponding analyses showed that the diphasic films, incorporated with a subtle boron compensation, could gain both the fine photosensitivity and high stability, provided the crystalline fraction ( f) was controlled in the range of 0< f<0.3. When compared with the conventional hydrogenated amorphous silicon (a-Si:H), the diphasic films are more ordered and robust in the microstructure, and have a less clustered phase in the Si-H bond configurations.

  17. Germanium detector passivated with hydrogenated amorphous germanium

    DOEpatents

    Hansen, William L.; Haller, Eugene E.

    1986-01-01

    Passivation of predominantly crystalline semiconductor devices (12) is provided for by a surface coating (21) of sputtered hydrogenated amorphous semiconductor material. Passivation of a radiation detector germanium diode, for example, is realized by sputtering a coating (21) of amorphous germanium onto the etched and quenched diode surface (11) in a low pressure atmosphere of hydrogen and argon. Unlike prior germanium diode semiconductor devices (12), which must be maintained in vacuum at cryogenic temperatures to avoid deterioration, a diode processed in the described manner may be stored in air at room temperature or otherwise exposed to a variety of environmental conditions. The coating (21) compensates for pre-existing undesirable surface states as well as protecting the semiconductor device (12) against future impregnation with impurities.

  18. Reversibility and criticality in amorphous solids

    DOE PAGES

    Regev, Ido; Weber, John; Reichhardt, Charles; ...

    2015-11-13

    The physical processes governing the onset of yield, where a material changes its shape permanently under external deformation, are not yet understood for amorphous solids that are intrinsically disordered. Here, using molecular dynamics simulations and mean-field theory, we show that at a critical strain amplitude the sizes of clusters of atoms undergoing cooperative rearrangements of displacements (avalanches) diverges. We compare this non-equilibrium critical behaviour to the prevailing concept of a ‘front depinning’ transition that has been used to describe steady-state avalanche behaviour in different materials. We explain why a depinning-like process can result in a transition from periodic to chaoticmore » behaviour and why chaotic motion is not possible in pinned systems. As a result, these findings suggest that, at least for highly jammed amorphous systems, the irreversibility transition may be a side effect of depinning that occurs in systems where the disorder is not quenched.« less

  19. Breakdown of elasticity in amorphous solids

    NASA Astrophysics Data System (ADS)

    Biroli, Giulio; Urbani, Pierfrancesco

    2016-12-01

    What characterizes a solid is the way that it responds to external stresses. Ordered solids, such as crystals, exhibit an elastic regime followed by a plastic regime, both understood microscopically in terms of lattice distortion and dislocations. For amorphous solids the situation is instead less clear, and the microscopic understanding of the response to deformation and stress is a very active research topic. Several studies have revealed that even in the elastic regime the response is very jerky at low temperature, resembling very much the response of disordered magnetic materials. Here we show that in a very large class of amorphous solids this behaviour emerges upon decreasing temperature, as a phase transition, where standard elastic behaviour breaks down. At the transition all nonlinear elastic moduli diverge and standard elasticity theory no longer holds. Below the transition, the response to deformation becomes history- and time-dependent.

  20. Reversibility and criticality in amorphous solids

    SciTech Connect

    Regev, Ido; Weber, John; Reichhardt, Charles; Dahmen, Karin A.; Lookman, Turab

    2015-11-13

    The physical processes governing the onset of yield, where a material changes its shape permanently under external deformation, are not yet understood for amorphous solids that are intrinsically disordered. Here, using molecular dynamics simulations and mean-field theory, we show that at a critical strain amplitude the sizes of clusters of atoms undergoing cooperative rearrangements of displacements (avalanches) diverges. We compare this non-equilibrium critical behaviour to the prevailing concept of a ‘front depinning’ transition that has been used to describe steady-state avalanche behaviour in different materials. We explain why a depinning-like process can result in a transition from periodic to chaotic behaviour and why chaotic motion is not possible in pinned systems. As a result, these findings suggest that, at least for highly jammed amorphous systems, the irreversibility transition may be a side effect of depinning that occurs in systems where the disorder is not quenched.