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Sample records for laser surface cleaning

  1. Laser surface cleaning

    SciTech Connect

    Crivella, E.C.; Freiwald, J.; Freiwald, D.A.

    1996-12-31

    Decontamination of contaminated metal and material recycle, two of 31 priority needs identified by the D&D focus group, are the most promising applications for laser ablation within the DOE complex. F2 Associates has developed a robotic laser ablation system that is capable of high contamination rates, waste volume reduction, surface pore cleaning, and real-time characterization of materials. It is being demonstrated that this system will be the most cost-effective technology for metal decontamination and material recycle.

  2. Laser cleaning -- A new surface cleaning method without pollutions

    SciTech Connect

    Lu, Y.F.; Aoyagi, Y.

    1994-12-31

    Surface contaminations are removed by laser irradiation with pulse output and short wavelength from various substrate such as magnetic head slide, glass and metals. Laser cleaning is a new dry process to remove surface organic contaminations without using ultrasonic cleaning in organic solvents. This provides a new dry process to clean different substrate surfaces and can take the place of conventional wet cleaning processes such as ultrasonic cleaning with CFC and other organic solvents. The mechanisms of laser cleaning may include laser photodecomposition, laser ablation and surface vibration due to the impact of laser pulse. It is found that short wavelength and short pulse duration are necessary for effective cleaning. It is also found that an appropriate energy density is critical to achieve effective cleaning without causing surface oxidation and secondary contamination.

  3. Laser surface cleaning of organic contaminants

    NASA Astrophysics Data System (ADS)

    Feng, Y.; Liu, Z.; Vilar, R.; Yi, X.-S.

    1999-08-01

    Laser surface cleaning process has been a useful and efficient technique for various industrial applications. The removal of photoresist contaminants on silicon wafers was investigated with a krypton fluoride (KrF) excimer laser, and the irradiated area was characterized using a profilometer, a scanning electronic microscopy (SEM), an Auger electron spectroscopy (AES) and a Fourier transition infrared spectroscopy (FT-IR). It was found that there exist an optimal number of pulses to remove the contaminant from the substrate surface without any laser-induced damage, depending on the laser density on the surface. A model to predict the optimal number of pulses, which agrees well with Beer-Lambert's law, is proposed and proved to be operable.

  4. In situ cleaning of probe surfaces by pulsed laser heating

    SciTech Connect

    Tagle, J.A.; Pospieszczyk, A.

    1984-09-01

    Inconel 600, Inconel 625 and austenitic steel (AISI 304LN) surfaces were cleaned in UHV by laser pulses of 1J total energy. Residual surface contamination layers were dissociated and desorbed. The surface cleanness degree reached was equivalent to that obtained by conventional cleaning techniques like bulk heating and sputtering by ion bombardment. A comparison between these three techniques is presented. The laser cleaning efficiency was found to be strongly dependent on the initial surface contamination degree and on the residual gas composition. In particular the effect of laser shots on the activation of the surface oxidation process at ambient pressures of about 10/sup -9/ mbar of CO was studied. The possibilities of using the laser heating technique as a tool in plasma edge diagnostic (in situ cleaning of probes, analysis of trapped particles, redeposition measurements,...) in fusion devices is discussed.

  5. Surface Analysis of the Laser Cleaned Metal Threads

    NASA Astrophysics Data System (ADS)

    Sokhan, M.; Hartog, F.; McPhail, D.

    The laser cleaning of the tarnished silver threads was carried out using Nd:YAG laser radiation at IR (1064 nm) and visible wavelengths (532 nm). The preliminary tests were made on the piece of silk with the silver embroidery with the clean and tarnished areas. FIBS and SIMS analysis were used for analysing the condition of the surface before and after laser irradiation. It was found that irradiation below 0.4 J/cm-2 and higher than 1.0 J/cm-2 fluences aggravates the process of tarnishing and leads to the yellowing effect. The results of preliminary tests were used for finding the optimum cleaning regime for the laser cleaning of the real museum artefact: "Women Riding Jacket" dated to the beginning of 18th century.

  6. Laser Cleaning of Corroded Steel Surfaces: A Comparison with Mechanical Cleaning Methods

    NASA Astrophysics Data System (ADS)

    Koh, Y. S.; Powell, J.; Kaplan, A.; Carlevi, J.

    Conservation often requires the removal of oxide layers from metal artifacts and new cleaning methods are being developed all the time. This paper provides a quantitative comparison of eight cleaning methods, three of which are mechanical (brushing or micro-blasting with Al2O3 or glass beads) and five of which are laser dependent (TEA CO2 or Nd:YAG laser, with or without surface water). Surface profilometry and scanning electron microscopy have been used to compare the cleaned surfaces with the original, known, surface geometries.

  7. LASER CLEANING OF CONTAMINATED PAINTED SURFACES

    SciTech Connect

    Ames A. Grisanti; Charlene R. Crocker; Robert R. Jensen

    1999-11-19

    Several techniques are available or under development for surface decontamination in nuclear facilities. Each technique has its merits; however, none of them is universally the best choice for all surface decontamination applications. Because of the multitude of factors which influence the environmental and economic aspects of selecting a surface decontamination technique, it is difficult to select the best method in a given situation; an objective basis for comparing techniques is needed. The objective of this project was to develop a software tool for use by personnel selecting a surface decontamination technique. The software incorporates performance data for available surface decontamination techniques. The beta release version of the Surface Decontamination Assistant Software has been completed and has undergone testing at the Energy and Environmental Research Center. Minor modifications to the software were completed, and a final release version of the software is ready to be issued.

  8. Laser Ablation Cleaning of Self-Reacting Friction Stir Weld Seam Surfaces: A Preliminary Evaluation

    NASA Technical Reports Server (NTRS)

    Nunes, A. C., Jr.; Russell, C. K.; Brooke, S. A.; Parry, Q.; Lowrey, N. M.

    2014-01-01

    Anodized aluminum panels were cleaned by three lasers at three separate sites with a view to determining whether more economical laser cleaning might supplant current manual cleaning methods for preparation of surfaces to be welded by the self-reacting friction stir process. Uncleaned panels yielded welds exhibiting residual oxide defect (ROD) and failing at very low stresses along the trace of the weld seam. Manually cleaned panels yielded welds without ROD; these welds failed at nominal stress levels along an angled fracture surface not following the weld seam trace. Laser cleaned panels yielded welds failing at intermediate stress levels. The inadequacy of the laser cleaning processes leaves questions: Was the anodized aluminum test too stringent to represent actual cleaning requirements? Were the wrong laser cleaning techniques/parameters used for the study? Is the laser cleaning mechanism inadequate for effective preweld surface cleaning?

  9. Comparative study of pulsed laser cleaning applied to weathered marble surfaces

    NASA Astrophysics Data System (ADS)

    Ortiz, P.; Antúnez, V.; Ortiz, R.; Martín, J. M.; Gómez, M. A.; Hortal, A. R.; Martínez-Haya, B.

    2013-10-01

    The removal of unwanted matter from surface stones is a demanding task in the conservation of cultural heritage. This paper investigates the effectiveness of near-infrared (IR) and ultraviolet (UV) laser pulses for the cleaning of surface deposits, iron oxide stains and different types of graffiti (black, red and green sprays and markers, and black cutting-edge ink) on dolomitic white marble. The performance of the laser techniques is compared to common cleaning methods on the same samples, namely pressurized water and chemical treatments. The degree of cleaning achieved with each technique is assessed by means of colorimetric measurements and X-ray microfluorescence. Eventual morphological changes induced on the marble substrate are monitored with optical and electronic microscopy. It is found that UV pulsed laser ablation at 266 nm manages to clean all the stains except the cutting-edge ink, although some degree of surface erosion is produced. The IR laser pulses at 1064 nm can remove surface deposits and black spray acceptably, but a yellowing is observed on the stone surface after treatment. An economic evaluation shows that pulsed laser cleaning techniques are advantageous for the rapid cleaning of small or inaccessible surface areas, although their extensive application becomes expensive due to the long operating times required.

  10. Lasers and applications in parts cleaning and surface pre-treatment

    NASA Astrophysics Data System (ADS)

    Burdel, Thomas; Weiler, Sascha; Faißt, Birgit; Schneider, Till; Heckl, Oliver; Birkel, Jörn; Luzius, Severin

    2013-02-01

    A number of upcoming industrial applications prove that the laser offers great possibilities for parts cleaning and surface pretreatment. Thereby laser technology enables solutions to reduce production costs and to increase productivity and quality in the manufacturing process. Examples are the removal of oil, grease, phosphate layers or corrosion with the laser. This paper will focus on parts cleaning and surface pretreatment applications within the automotive industry. For a range of examples it will be shown that the laser not only offers advantages to carry out the described production step (such as cleaning or the creation of functional textures) but also offers great advantages for a following production step within the chain, such as a welding or gluing process. It will be demonstrated that several ns and ps laser sources and systems can be selected, depending on the application.

  11. Pulsed laser cleaning of aluminium-magnesium alloys: effect of surface modifications on adhesion

    NASA Astrophysics Data System (ADS)

    Autric, Michel; Oltra, Roland

    2008-05-01

    Surface cleaning is a key step in many industrial processes and especially in laser surface treatments. During laser cleaning of metallic alloys using pulsed lasers, surface modification can be induced due to transient thermal effect. In ambient atmospheric conditions, an oxidation of the cleaned surface can be detected. The aim of this work was to characterize this transient oxidation that can occur below the laser energy domain leading to any phase change (melting, ablation) of the cleaned substrate. A Q-switched Nd:YAG laser (1.06 μm) with 10 ns pulse duration was used for this study. X-ray photoelectron spectroscopy and secondary ion mass spectroscopy were used for surface analysis of irradiated samples. Thermal oxidation took place on the aluminium-magnesium alloy (5000 series) during the irradiation in air (fluence range 0.6-1.4 Jcm-2). It has been demonstrated that this 10 ns laser thermal oxidation and the steady state thermal oxidation have the same mechanism. When the laser fluence reached 1 J cm -2 , the oxide formed by the thermal oxidation became in a large extent crystalline and its outer part was entirely covered by a continuous magnesium oxide layer.

  12. How to clean surfaces

    NASA Astrophysics Data System (ADS)

    Bennett, Jean M.

    2004-06-01

    Various cleaning methods are available depending on the sizes of the parts, mounted or unmounted, and purpose of the cleaning. Dust and other particle contamination affect scattering and act as nuclei for defects in optical coatings. In some cases, these defects can initiate laser damage. Noncontact cleaning methods to eliminate particle contamination include blowing large particles from surfaces with an air bulb, "canned air," or a nitrogen gas jet, for a gentle cleaning and CO2 snow for more aggressive particle removal. Laser assisted particle removal is a new high tech method. A strip coating material applied to the surface and subsequently removed will remove large fresh particles and often fingerprints. Contamination films affect the quality and adherence of optical coatings. These are usually removed (from unmounted optics) by cleaning the surface in a detergent and water bath followed by extensive rinsing and non-contact drying. Alternate methods when immersion in water is not possible are drag wiping, or spraying or squirting organic solvents over the surface. Before cleaning, surfaces must be visually inspected to determine the type and location of the contamination, to decide if cleaning is necessary, and what type of cleaning technique to use. Finally, bad cleaning is much worse than no cleaning! Illustrations of the cleaning methods described above will be given.

  13. Laser Cleaning of Avian Eggshell

    NASA Astrophysics Data System (ADS)

    Cornish, L.; Ball, A.; Russell, D.

    A low vacuum SEM was used to evaluate the effect of using an Nd:YAG laser as a non-contact technique for cleaning avian eggshells. The technique shows potential, since there are no obvious deleterious effects from cleaning, but further study is required to understand how the laser is interacting with the sample surface.

  14. Method using laser irradiation for the production of atomically clean crystalline silicon and germanium surfaces

    DOEpatents

    Ownby, G.W.; White, C.W.; Zehner, D.M.

    1979-12-28

    This invention relates to a new method for removing surface impurities from crystalline silicon or germanium articles, such as off-the-shelf p- or n-type wafers to be doped for use as junction devices. The principal contaminants on such wafers are oxygen and carbon. The new method comprises laser-irradiating the contaminated surface in a non-reactive atmosphere, using one or more of Q-switched laser pulses whose parameters are selected to effect melting of the surface without substantial vaporization thereof. In a typical application, a plurality of pulses is used to convert a surface region of an off-the-shelf silicon wafer to an atomically clean region. This can be accomplished in a system at a pressure below 10-/sup 8/ Torr, using Q-switched ruber-laser pulses having an energy density in the range of from about 60 to 190 MW/cm/sup 2/.

  15. Method using laser irradiation for the production of atomically clean crystalline silicon and germanium surfaces

    DOEpatents

    Ownby, Gary W.; White, Clark W.; Zehner, David M.

    1981-01-01

    This invention relates to a new method for removing surface impurities from crystalline silicon or germanium articles, such as off-the-shelf p- or n-type wafers to be doped for use as junction devices. The principal contaminants on such wafers are oxygen and carbon. The new method comprises laser-irradiating the contaminated surface in a non-reactive atmosphere, using one or more of Q-switched laser pulses whose parameters are selected to effect melting of the surface without substantial vaporization thereof. In a typical application, a plurality of pulses is used to convert a surface region of an off-the-shelf silicon wafer to an automatically clean region. This can be accomplished in a system at a pressure below 10.sup.-8 Torr, using Q-switched ruby-laser pulses having an energy density in the range of from about 60 to 190 MW/cm.sup.2.

  16. Surface modification during Nd:YAG (1064 nm) pulsed laser cleaning of organic fibrous materials

    NASA Astrophysics Data System (ADS)

    Strlič, Matija; Kolar, Jana; Šelih, Vid-Simon; Marinček, Marko

    2003-02-01

    Formation of yellow chromophores on artificially soiled surfaces of cellulose sheets, rag paper, linen, cotton, wool and silk during Nd:YAG (1064 nm) pulsed laser cleaning was followed using Vis and FTIR diffuse reflectance spectrometry. Content of reducing carbonyl groups and changes in FTIR reflectance spectra of cellulose are indicative of surface chemical modifications typical of thermal degradation at elevated temperatures. Two types of soiling were used: well-characterised natural dust and carbon powder and no difference in laser-induced formation of chromophores on material surface was observed at low deposit densities. The influence of laser fluence and number of repetitions was studied and a single pulse of a higher fluence (1 J cm -1) is in general more advisable. No bleaching of the chromophores formed was noticed after repeated treatments.

  17. The effects of short pulse laser surface cleaning on porosity formation and reduction in laser welding of aluminium alloy for automotive component manufacture

    NASA Astrophysics Data System (ADS)

    AlShaer, A. W.; Li, L.; Mistry, A.

    2014-12-01

    Laser welding of aluminium alloys typically results in porosity in the fusion zones, leading to poor mechanical and corrosion performances. Mechanical and chemical cleaning of surfaces has been used previously to remove contaminants for weld joint preparations. However, these methods are slow, ineffective (e.g. due to hydrogen trapping) or lead to environmental hazards. This paper reports the effects of short pulsed laser surface cleaning on porosity formation and reduction in laser welding of AC-170PX (AA6014) aluminium sheets (coated with Ti/Zr and lubricated using a dry lubricant AlO70) with two types of joints: fillet edge and flange couch, using an AA4043 filler wire for automotive component assembly. The effect of laser cleaning on porosity reduction during laser welding using a filler wire has not been reported before. In this work, porosity and weld fusion zone geometry were examined prior to and after laser cleaning. The nanosecond pulsed Nd:YAG laser cleaning was found to reduce porosity significantly in the weld fusion zones. For the fillet edge welds, porosity was reduced to less than 0.5% compared with 10-80% without laser cleaning. For flange couch welds, porosity was reduced to 0.23-0.8% with laser cleaning from 0.7% to 4.3% without laser cleaning. This has been found to be due to the elimination of contaminations and oxide layers that contribute to the porosity formation. The laser cleaning is based on thermal ablation. This research focuses on porosity reduction in laser welding of aluminium alloy. Weld quality was investigated for two joints, fillet edge and flange couch joints. The effect of laser cleaning on porosity reduction after welding was investigated. It was found that laser cleaning reduced porosity less than 1% in both joints. Weld dimensions and strength were evaluated and discussed for both types of joints.

  18. Fiber laser cleaning of metal mirror surfaces for optical diagnostic systems of the ITER

    SciTech Connect

    Kuznetsov, A. P. Alexandrova, A. S.; Buzhinsky, O. I.; Gubskiy, K. L.; Kazieva, T. V.; Savchenkov, A. V.; Tugarinov, S. N.

    2015-12-15

    The results of experimental studies into efficiency of removal of films with a complex composition from metal mirrors by pulsed fiber laser irradiation are presented. It is shown that the initial reflectivity of optical elements can be restored by the selection of modes of irradiation impacting the surface with the sputtered film. Effective cleaning is performed by radiation with a power density lower than 10{sup 7} W/cm{sup 2}. The removal of contaminations at such a relatively low power density occurs in a solid phase, owing to which the thermal effect on the mirror is insignificant.

  19. New laser surface treatments: cleaning, derusting, deoiling, depainting, deoxidizing, and degreasing

    NASA Astrophysics Data System (ADS)

    Daurelio, Giuseppe; Chita, Giuseppe; Cinquepalmi, Massimo

    1997-08-01

    Many materials as substrates and surface products have been tested. Typically ferrous (Carbon Steels and Stainless Steels) and non ferrous (Al and Cu metals and its alloys) ones have been employed. Some epoxy, polyurethane, polyester and acrylic paints in different thickness and color have been tested. Many types of the surface rust and oxide on different bulk material have been undertaken to test. Similarly some different types of oils and greases, usually used in industry against the oxidation, have been studied. Anyway many types of dirt, grit, calcareous one and so on, present on industrial components, have been laser cleaned without using solvents, acid baths and other ones. Different types of laser sources have been employed: an axial fast flow, 1.5 KW CO2 c.w. and pulsed laser source, emitting a 10.6 micrometers beam; a portable CO2 laser, c.w. (1 to 25 W) and pulsed (1 to 100 Hz and 400 ms max pulse duration) source, emitting a 10.6 micrometers beam with a multi-articulated seven mirrors guiding device and focussing head; a portable Nd-YAG laser, Q-switched and normal-mode source. 1st harmonic 1.06 micrometers (6 ns pulse duration), 2nd harmonic 532 nm (120 microsecond(s) duration pulse- 1J max per-pulse) wavelengths, multi-articulated seven mirrors beam guiding device, 20 Hz repetition rate. This lets shots with 600 mJ max energy per pulse and 100 MW peak power per-pulse with a very low beam divergence, 0.5 mrad at full angle; a transverse fast flow 2.5 kW CO2 laser.

  20. Laser cleaning on Roman coins

    NASA Astrophysics Data System (ADS)

    Drakaki, E.; Karydas, A. G.; Klinkenberg, B.; Kokkoris, M.; Serafetinides, A. A.; Stavrou, E.; Vlastou, R.; Zarkadas, C.

    Ancient metal objects react with moisture and environmental chemicals to form various corrosion products. Because of the unique character and high value of such objects, any cleaning procedure should guarantee minimum destructiveness. The most common treatment used is mechanical stripping, in which it is difficult to avoid surface damage when employed. Lasers are currently being tested for a wide range of conservation applications. Since they are highly controllable and can be selectively applied, lasers can be used to achieve more effective and safer cleaning of archaeological artifacts and protect their surface details. The basic criterion that motivated us to use lasers to clean Roman coins was the requirement of pulsed emission, in order to minimize heat-induced damages. In fact, the laser interaction with the coins has to be short enough, to produce a fast removal of the encrustation, avoiding heat conduction into the substrate. The cleaning effects of three lasers operating at different wavelengths, namely a TEA CO2 laser emitting at 10.6 μm, an Er:YAG laser at 2.94 μm, and a 2ω-Nd:YAG laser at 532 nm have been compared on corroded Romans coins and various atomic and nuclear techniques have also been applied to evaluate the efficiency of the applied procedure.

  1. Research of laser cleaning technology for steam generator tubing

    NASA Astrophysics Data System (ADS)

    Hou, Suixa; Luo, Jijun; Xu, Jun; Yuan, Bo

    2010-10-01

    Surface cleaning based on the laser-induced breakdown of gas and subsequent shock wave generation can remove small particles from solid surfaces. Accordingly, several studies in steam generator tubes of nuclear power plants were performed to expand the cleaning capability of the process. In this work, experimental apparatus of laser cleaning was designed in order to clean heat tubes in steam generator. The laser cleaning process is monitored by analyzing acoustic emission signal experimentally. Experiments demonstrate that laser cleaning can remove smaller particles from the surface of steam generator tubes better than other cleaning process. It has advantages in saving on much manpower and material resource, and it is a good cleaning method for heat tubes, which can be real-time monitoring in laser cleaning process of heat tubes by AE signal. As a green cleaning process, laser cleaning technology in equipment maintenance will be a good prospect.

  2. Improve the laser damage resistance of fused silica by wet surface cleaning and optimized HF etch process

    NASA Astrophysics Data System (ADS)

    Jiang, Xiaolong; Liu, Ying; Rao, Huanle; Fu, Shaojun

    2013-07-01

    Fabrication-induced metal contaminations and subsurface damage are generally identified as the laser damage initiators that are responsible for the laser induced damage in fused silica. In this paper, the removal of those two initiators are realized by two methods: wet chemical surface cleaning and optimized HF-based etch process. Two kinds of chemical leaching are used to removing the Ce and other metal impurities respectively. In order prevent the redeposition of the reactive byproducts during HF etch process, we optimized the traditional HF etch process in two ways: absence of NH4F in etch solution and presence of megasonic and ultrasonic agitation during and after etch respectively. And laser damage tests show that these two treatments greatly improve the laser damage resistance of fused silica.

  3. Influence of surface laser cleaning combined with substrate preheating on the splat morphology

    NASA Astrophysics Data System (ADS)

    Costil, S.; Liao, H.; Gammoudi, A.; Coddet, C.

    2005-03-01

    The morphology of sprayed splats influences the coating adhesion and properties, which are determined by the spraying parameters. Many studies in this field show that the substrate surface temperature is a very relevant factor for the splat shape: the hypotheses of substrate surface wettability and contamination or adsorption layer on the surfaces are supported by the fact that the near-disk-shaped splat can be obtained by increasing the substrate temperature. In this work, a short-duration pulsed laser was used to ablate the substrate just before powder spraying. This ablation was powerful enough to eliminate the contaminants on the substrate surface and to improve the adhesion. In this study the analyses of NiAl splat morphology on the polished TA6V (Ti-6Al-4V) substrate were carried out using laser ablation with different substrate temperatures and different heating modes: the flame and another laser. Results show that the temperature at which the disk-shaped splat can be obtained decreased dramatically by laser ablation. Moreover, laser ablation combined with another laser increased the adhesion strength of the coatings.

  4. ``Verso'' laser cleaning of mechanically thin films

    NASA Astrophysics Data System (ADS)

    Barone, Alberto; Bloisi, Francesco; Vicari, Luciano

    2003-03-01

    In usual dry laser cleaning of opaque samples, short laser pulses are projected onto the sample surface to be cleaned. Energy transferred from light ejects extraneous particles away from the surface. Laser beam fluence is limited by the damage reached by high temperature that the sample surface can produce. We have experimentally shown that for thin samples, the thermo-elastic wave propagates within the whole sample thickness, thus also the rear surface, while temperature effects are limited to the front surface. Therefore, the proposed "verso" laser cleaning technique (the pulsed laser beam impinges on rear sample surface) can be applied to any opaque "mechanically thin" film and is useful for samples having delicate treatments on the surface to be cleaned (e.g. written paper, painted tiles, magnetic films). We have applied our technique to paper sheets showing that it is possible to efficiently clean the surface without damaging ink marks on it. Using a probe beam deflection (PBD) technique in both direct and reverse configuration we have shown that the "verso" cleaning effect is due to the higher penetration depth of the thermo-elastic wave with respect to the temperature profile propagation.

  5. Development of a laser cleaning method for the first mirror surface of the charge exchange recombination spectroscopy diagnostics on ITER

    SciTech Connect

    Kuznetsov, A. P.; Buzinskij, O. I.; Gubsky, K. L.; Nikitina, E. A.; Savchenkov, A. V.; Tarasov, B. A.; Tugarinov, S. N.

    2015-12-15

    A set of optical diagnostics is expected for measuring the plasma characteristics in ITER. Optical elements located inside discharge chambers are exposed to an intense radiation load, sputtering due to collisions with energetic atoms formed in the charge transfer processes, and contamination due to recondensation of materials sputtered from different parts of the construction of the chamber. Removing the films of the sputtered materials from the mirrors with the aid of pulsed laser radiation is an efficient cleaning method enabling recovery of the optical properties of the mirrors. In this work, we studied the efficiency of removal of metal oxide films by pulsed radiation of a fiber laser. Optimization of the laser cleaning conditions was carried out on samples representing metal substrates polished with optical quality with deposition of films on them imitating the chemical composition and conditions expected in ITER. It is shown that, by a proper selection of modes of radiation exposure to the surface with a deposited film, it is feasible to restore the original high reflection characteristics of optical elements.

  6. Development of a laser cleaning method for the first mirror surface of the charge exchange recombination spectroscopy diagnostics on ITER

    NASA Astrophysics Data System (ADS)

    Kuznetsov, A. P.; Buzinskij, O. I.; Gubsky, K. L.; Nikitina, E. A.; Savchenkov, A. V.; Tarasov, B. A.; Tugarinov, S. N.

    2015-12-01

    A set of optical diagnostics is expected for measuring the plasma characteristics in ITER. Optical elements located inside discharge chambers are exposed to an intense radiation load, sputtering due to collisions with energetic atoms formed in the charge transfer processes, and contamination due to recondensation of materials sputtered from different parts of the construction of the chamber. Removing the films of the sputtered materials from the mirrors with the aid of pulsed laser radiation is an efficient cleaning method enabling recovery of the optical properties of the mirrors. In this work, we studied the efficiency of removal of metal oxide films by pulsed radiation of a fiber laser. Optimization of the laser cleaning conditions was carried out on samples representing metal substrates polished with optical quality with deposition of films on them imitating the chemical composition and conditions expected in ITER. It is shown that, by a proper selection of modes of radiation exposure to the surface with a deposited film, it is feasible to restore the original high reflection characteristics of optical elements.

  7. Cleaning of large area by excimer laser ablation

    NASA Astrophysics Data System (ADS)

    Sentis, Marc L.; Delaporte, Philippe C.; Marine, Wladimir I.; Uteza, Olivier P.

    2000-01-01

    Surface removal technologies are being challenged from environmental and economic perspectives. This paper is concerned with laser ablation applied to large surface cleaning with an automatized excimer laser unit. The study focused on metallic surfaces that are oxidized and are representative of contaminated surfaces with radionuclides in a context of nuclear power plant maintenance. The whole system is described: laser, beam deliver, particle collection cell, real time control of cleaning processes. Results concerning surface laser interaction and substrate modifications are presented.

  8. Characterization of Laser Cleaning of Artworks

    PubMed Central

    Marczak, Jan; Koss, Andrzej; Targowski, Piotr; Góra, Michalina; Strzelec, Marek; Sarzyński, Antoni; Skrzeczanowski, Wojciech; Ostrowski, Roman; Rycyk, Antoni

    2008-01-01

    The main tasks of conservators of artworks and monuments are the estimation and analysis of damages (present condition), object conservation (cleaning process), and the protection of an object against further degradation. One of the physical methods that is becoming more and more popular for dirt removal is the laser cleaning method. This method is non-contact, selective, local, controlled, self-limiting, gives immediate feedback and preserves even the gentlest of relief - the trace of a paintbrush. Paper presents application of different, selected physical sensing methods to characterize condition of works of art as well as laser cleaning process itself. It includes, tested in our laboratories, optical surface measurements (e.g. colorimetry, scatterometry, interferometry), infrared thermography, optical coherent tomography and acoustic measurements for “on-line” evaluation of cleaning progress. Results of laser spectrometry analyses (LIBS, Raman) will illustrate identification and dating of objects superficial layers.

  9. Task 12: Laser cleaning of contaminated painted surfaces. Semi-annual report, April 1, 1996--September 30, 1996

    SciTech Connect

    Grisanti, A.A.; Hassett, D.J.

    1997-05-01

    Paint contaminated with radionuclides and other hazardous materials is common in Department of Energy (DOE) facilities. Facility decommissioning and decontamination requires the removal of contaminated paint. Paint removal technologies include laser- and abrasive-based systems. F2 Associates are utilizing a pulsed-repetition CO{sub 2} laser that produces a 2.5-cm x 2.5-cm beam which can be scanned across a 30- x 100-cm raster and, when placed on a robot, can be designed to clean any surface that the robot can be programmed to follow. Causing little or no damage to the substrate (concrete, steel, etc.), the laser ablates the material to be removed from a given surface. Ablated material is then pulled into a filtration and collection (VAC-PAC) system to prevent the hazardous substances from entering into the atmosphere. The VAC-PAC system deposits the ablated material into waste drums which may be removed from the system without compromising the integrity of the seal, allowing a new drum to be set up for collection without leakage of the ablated material into the atmosphere.

  10. Laser cleaning treatment of burnt paintings

    NASA Astrophysics Data System (ADS)

    Antonopoulou-Athera, N.; Chatzitheodoridis, E.; Doulgerides, M.; Evangelatos, Ch.; Serafetinides, A. A.; Terlixi, A.

    2015-01-01

    Three samples taken from two paintings partly burned by fire are investigated for cleaning with lasers. The paintings belong to the collection of the National Gallery of Athens and were made by the great Greek artist Konstantinos Parthenis. To remove the damaged surface and achieve an acceptable restoration result, the optimum combination of fluence and wavelength are sought. Seven different wavelengths with a set of fluences where used, i.e., the five harmonics of a Nd:YAG laser (1064, 532, 355, 266, and 213 nm), a TEA 10.6 μm CO2 and a free running laser Er:YAG 2.94 μm. Characterization was performed prior and after the cleaning process by optical and electron microscopy and analysis (SEM/BSE EDS), as well as X-Ray Diffraction (XRD). The results of this work indicate that the wavelength in the visible spectrum (532 nm) with fluences between 0.1-0.4J/cm2 show the optimum cleaning. The optical microscopy observation shows that with these laser parameters the burnt layer was preferentially removed, exposing the original colors that Parthenis had used in these paintings. Electron microscopy imaging and chemical analysis revealed that the original texture and materials of these samples are preserved after irradiation. Since the damage varies along the surface of the painting, more experiments should be performed in order to find and optimize the full cleaning and characterization process for the homogeneous cleaning of the whole surface of the painting.

  11. Laser cleaning of paintings: from preliminary investigations to a laser cleaning station

    NASA Astrophysics Data System (ADS)

    Apostol, I.; Damian, V.; Garoi, F.; Iordache, I.; Bojan, M.; Apostol, D.; Morais, P. J.; Postolache, D.; Darida, I.

    2010-11-01

    UV laser beam interaction with painting layers in case of aged mock-ups was investigated and ablation and cleaning thresholds were estimated as a function of each layer and sub-layer composition. Ablation depth measurements as a function of incident laser intensities and subsequent irradiation pulse number was measured with white light interferometry (WLI) and profilometric methods, demonstrating a selectivity of the removal of painting layers from submicrometric domain to micrometric domain as a function of surface cleaning needs. The laser cleaning station was designed and developed after careful evaluation of the irradiation conditions proper to the removal of painting layers. A Q-switched Nd:Yag laser radiation is delivered to the artwork through a mirror system consisting in an articulated arm and a laser head. A complete control of the incident laser parameters was envisaged with the laser remote control interface. The system also comprises diagnosis and monitoring tools for the remote control of the cleaning operation. The prototype is controlled by an integrated interface based on a user-friendly software to perform the available operations (e.g. laser cleaning, LIBS, colorimetry, live color monitoring, multispectral analysis, database management). The user interface is also used to start the treatment of a new work, to review or continue a previously started work.

  12. Laser Cleaning of Contaminated Painted Surfaces. Semiannual report, November 1, 1996--March 31, 1997

    SciTech Connect

    Grisanti, Ames A.; Jensen, Robert R.

    1997-12-31

    The objective of this project is to develop a software tool for use by personnel who must select a surface decontamination technique. The software will incorporate performance data for available surface decontamination techniques. The major activities in the project are broken down as follows: Task 1 - Complete decision tree development. Task 2 - Literature search for surface decontamination reports. Task 3 - Compilation of database from literature data. Task 4 - Sensitivity analysis and model design. Task 5 - Design of model data structures. Task 6 - PC software design and coding

  13. METHOD OF CLEANING METAL SURFACES

    DOEpatents

    Winkler, H.W.; Morfitt, J.W.; Little, T.H.

    1959-05-19

    Cleaning fluids for removing deposits from metal surfaces are described. The cleaning agents of the invention consist of aqueous nitric acid and an amhydrous nitrate salt of a metal which is lower in the electromotive series than the element of the deposit to be removed. In general, the salt content of thc cleaning agents ranged from 10 to 90%, preferably from 10 to 40% by weight; and the balance of the composition comprises nitric acid of any strength from extremely dilute up to concentrated strength.

  14. Nd:YAG laser cleaning of ablation debris from excimer-laser-ablated polyimide

    NASA Astrophysics Data System (ADS)

    Gu, Jianhui; Low, Jason; Lim, Puay K.; Lim, Pean

    2001-10-01

    In the processing of excimer laser ablation of nozzles on polyimide in air, both gases like CO2, CO and HCN and solid debris including C2 approximately C12 are produced in laser ablation area. In this paper, we reported for the first time a Nd:YAG laser cleaning of ablation debris generated in excimer laser ablation of polyimide. It demonstrated effective cleaning with the advantages of shortening cleaning cycle time and simplifying cleaning process. The laser used for the cleaning was a Q-switched and frequency doubled Nd:YAG laser with wavelength of 532 nm and repetition rate of 10 Hz. The laser cleaning effect was compared with conventional plasma ashing. AFM measurement showed that the Nd:YAG laser cleaning had no damage to the substrate. XPS results indicated that the polyimide surface cleaned with laser beam had a lower oxygen/carbon ratio than that of plasma ashing. The study shows that frequency doubled Nd:YAG laser cleaning is effective in ablation debris removal from excimer laser ablated polyimide.

  15. MiniCLEAN surface backgrounds

    NASA Astrophysics Data System (ADS)

    Wang, Boqian; Schnee, Richard; Deap/Clean Collaboration

    2011-04-01

    MiniCLEAN is a dark matter experiment using 150kg fiducial mass of liquid cryogen (argon or neon) to search for Weakly Interacting Massive Particles (WIMPs). MiniCLEAN seeks to detect scintillation photons from WIMP-induced argon recoils. A potentially dominant background is from alpha decays on the inner surfaces of the containment vessel. Such events can mimic the prompt signal characteristic of nuclear recoils. This talk will show the expected background rates, methods of background discrimination, and their expected effectiveness.

  16. Laser cleaning of varnishes and contaminants on brass

    NASA Astrophysics Data System (ADS)

    Mateo, M. P.; Ctvrtnickova, T.; Fernandez, E.; Ramos, J. A.; Yáñez, A.; Nicolas, G.

    2009-03-01

    The capability of laser ablation to perform controlled cleaning of varnishes containing contaminants and paints used by restorers in artistic objects from brass samples while keeping unaltered the finish structure is demonstrated in this work. Adequate laser energy per pulse and number of laser shots required to perform a suitable cleaning by laser ablation have been optimized. The inspection of the samples before and after the cleaning process by optical microscopy and by Fourier transform infrared spectroscopy (FTIR) technique demonstrated that the finish structure of the surface was intact while the coatings were completely eliminated. Furthermore, a laser-induced plasma spectroscopy (LIBS)-based detection system was applied during the irradiation process for the analysis of the material removal and also for its monitoring.

  17. Ultrasonic cleaning of interior surfaces

    DOEpatents

    Odell, D. MacKenzie C.

    1996-01-01

    An ultrasonic cleaning method for cleaning the interior surfaces of tubes. The method uses an ultrasonic generator and reflector each coupled to opposing ends of the open-ended, fluid-filled tube. Fluid-tight couplings seal the reflector and generator to the tube, preventing leakage of fluid from the interior of the tube. The reflector and generator are operatively connected to actuators, whereby the distance between them can be varied. When the distance is changed, the frequency of the sound waves is simultaneously adjusted to maintain the resonant frequency of the tube so that a standing wave is formed in the tube, the nodes of which are moved axially to cause cavitation along the length of the tube. Cavitation maximizes mechanical disruption and agitation of the fluid, dislodging foreign material from the interior surface.

  18. Ultrasonic cleaning of interior surfaces

    DOEpatents

    MacKenzie, D.; Odell, C.

    1994-03-01

    An ultrasonic cleaning apparatus is described for cleaning the interior surfaces of tubes. The apparatus includes an ultrasonic generator and reflector each coupled to opposing ends of the open-ended, fluid-filled tube. Fluid-tight couplings seal the reflector and generator to the tube, preventing leakage of fluid from the interior of the tube. The reflector and generator are operatively connected to actuators, whereby the distance between them can be varied. When the distance is changed, the frequency of the sound waves is simultaneously adjusted to maintain the resonant frequency of the tube so that a standing wave is formed in the tube, the nodes of which are moved axially to cause cavitation along the length of the tube. Cavitation maximizes mechanical disruption and agitation of the fluid, dislodging foreign material from the interior surface. 3 figures.

  19. Ultrasonic cleaning of interior surfaces

    DOEpatents

    Odell, D. MacKenzie C.

    1994-01-01

    An ultrasonic cleaning apparatus for cleaning the interior surfaces of tubes. The apparatus includes an ultrasonic generator and reflector each coupled to opposing ends of the open-ended, fluid-filled tube. Fluid-tight couplings seal the reflector and generator to the tube, preventing leakage of fluid from the interior of the tube. The reflector and generator are operatively connected to actuators, whereby the distance between them can be varied. When the distance is changed, the frequency of the sound waves is simultaneously adjusted to maintain the resonant frequency of the tube so that a standing wave is formed in the tube, the nodes of which are moved axially to cause cavitation along the length of the tube. Cavitation maximizes mechanical disruption and agitation of the fluid, dislodging foreign material from the interior surface.

  20. Ultrasonic cleaning of interior surfaces

    SciTech Connect

    Odell, D.M.C.

    1996-06-25

    An ultrasonic cleaning method is described for cleaning the interior surfaces of tubes. The method uses an ultrasonic generator and reflector each coupled to opposing ends of the open-ended, fluid-filled tube. Fluid-tight couplings seal the reflector and generator to the tube, preventing leakage of fluid from the interior of the tube. The reflector and generator are operatively connected to actuators, whereby the distance between them can be varied. When the distance is changed, the frequency of the sound waves is simultaneously adjusted to maintain the resonant frequency of the tube so that a standing wave is formed in the tube, the nodes of which are moved axially to cause cavitation along the length of the tube. Cavitation maximizes mechanical disruption and agitation of the fluid, dislodging foreign material from the interior surface. 3 figs.

  1. Cleaning Process Versus Laser-Damage Threshold of Coated Optical Components

    SciTech Connect

    Rigatti, A.L.

    2005-03-31

    The cleaning of optical surfaces is important in the manufacture of high-laser-damage-threshold coatings, which are a key component on peak-power laser systems such as OMEGA located at the Laboratory for Laser Energetics (LLE). Since cleaning adds time, labor, and ultimately cost to the final coated component, this experiment was designed to determine the impact of different cleaning protocols on the measured laser-damage performance.

  2. Analysis of selective laser cleaning of patina on bronze coins

    NASA Astrophysics Data System (ADS)

    Buccolieri, G.; Nassisi, V.; Torrisi, L.; Buccolieri, A.; Castellano, A.; Di Giulio, M.; Giuffreda, E.; Delle Side, D.; Velardi, L.

    2014-04-01

    The patina, is the result of a large number of chemical, electrochemical and physical processes which occur spontaneously during interaction of metal surfaces with the environment. In this work we want to analyze and remove the patina in artefacts, exposed to atmosphere for various decades. Here, experimental results about the laser cleaning of bronze coins by KrF (248 nm) and Nd:YAG (532 nm) lasers are reported. Both laser wavelengths were efficient to reduce the chlorine concentration on the surface of the coins more than 80 %, as demonstrated by Energy Dispersive X-Ray Fluorescence analyses.

  3. Laser cleaning of diagnostic mirrors from tokamak-like carbon contaminants

    NASA Astrophysics Data System (ADS)

    Maffini, A.; Uccello, A.; Dellasega, D.; Russo, V.; Perissinotto, S.; Passoni, M.

    2015-08-01

    This paper presents a laboratory-scale experimental investigation of laser cleaning of diagnostic First Mirrors (FMs). Redeposition of contaminants sputtered from tokamak first wall onto FMs surface could dramatically decrease their reflectivity in an unacceptable way for the functioning of the plasma diagnostic systems. Laser cleaning is a promising solution to tackle this issue. In this work, pulsed laser deposition was exploited to produce rhodium films functional as FMs and to deposit onto them carbon contaminants with tailored features, resembling those found in tokamaks. The same laser system was also used to perform laser cleaning experiments by means of a sample handling procedure that allows to clean some cm2 in few minutes. The cleaning effectiveness was evaluated in terms of specular reflectivity recovery and mirror surface integrity. The effect of different laser wavelengths (λ = 1064, 266 nm) on the cleaning process is also addressed.

  4. Diode laser potential in laser cleaning of stones

    NASA Astrophysics Data System (ADS)

    Salimbeni, Renzo; Pini, Roberto; Siano, Salvatore; Bachmann, Friedrich G.; Meyer, Frank

    2001-10-01

    In this work we investigated for the first time the laser cleaning process of encrusted stones by employing a high power diode laser system. The test have been carried out using a Rofin-Sinar mod. DL025S emitting up to 2.5 kW CW power to clean various samples representing natural encrustation by pollution exposition and graffiti, typically encountered on historical monuments and buildings in urban environment.

  5. In situ window cleaning by laser blowoff through optical fibera)

    NASA Astrophysics Data System (ADS)

    Alfier, A.; Barison, S.; Danieli, T.; Giudicotti, L.; Pagura, C.; Pasqualotto, R.

    2008-10-01

    The feasibility of a window cleaning system based on the laser blowoff technique is investigated to remove the impurity deposition on vacuum windows of the modified reversed field experiment fusion device. The laser pulse is sent to the window through a fused silica fiber optic (φ=1mm), then focused on its internal surface, single shot ablating up to ˜5mm2 of the impurity layer; the focused pulse is scanned across the window to clean its entire surface. The composition of the deposited layer is studied through the secondary ion mass spectrometry and profilometry techniques. Effectiveness of cleaning is analyzed in terms of quality of the cleaned spot, its dimension, repetition rate of the laser, and its wavelength. The energy damage threshold of the fiber optic is also investigated. Three different lasers (microjoule Nd:YAG, Nd:YLF, and ruby) are first tested directly on the window; then only the ruby laser beam is propagated through an optical fiber and tested.

  6. Laser cleaning of ITER's diagnostic mirrors

    NASA Astrophysics Data System (ADS)

    Skinner, C. H.; Gentile, C. A.; Doerner, R.

    2012-10-01

    Practical methods to clean ITER's diagnostic mirrors and restore reflectivity will be critical to ITER's plasma operations. We report on laser cleaning of single crystal molybdenum mirrors coated with either carbon or beryllium films 150 - 420 nm thick. A 1.06 μm Nd laser system provided 220 ns pulses at 8 kHz with typical power densities of 1-2 J/cm^2. The laser beam was fiber optically coupled to a scanner suitable for tokamak applications. The efficacy of mirror cleaning was assessed with a new technique that combines microscopic imaging and reflectivity measurements [1]. The method is suitable for hazardous materials such as beryllium as the mirrors remain sealed in a vacuum chamber. Excellent restoration of reflectivity for the carbon coated Mo mirrors was observed after laser scanning under vacuum conditions. For the beryllium coated mirrors restoration of reflectivity has so far been incomplete and modeling indicates that a shorter duration laser pulse is needed. No damage of the molybdenum mirror substrates was observed.[4pt][1] C.H. Skinner et al., Rev. Sci. Instrum. at press.

  7. Cleaning laser spark spectroscopy for online cleaning quality control method development

    NASA Astrophysics Data System (ADS)

    Mutin, T. Y.; Smirnov, V. N.; Veiko, V. P.; Volkov, S. A.

    2010-07-01

    This work is dedicated to spectroscopic investigations of laser spark during the laser cleaning process. The goal is to proof its analytical possibilities for chemical composition determination for online cleaning quality control. Photographic recordings of laser spark were performed to estimate its parameters. Fiber spectrometer was used to analyze the emission of cleaning process established with fiber laser. Conclusions have been made about fiber laser radiation usability for spectroscopic purpose.

  8. Cleaning laser spark spectroscopy for online cleaning quality control method development

    NASA Astrophysics Data System (ADS)

    Mutin, T. Y.; Smirnov, V. N.; Veiko, V. P.; Volkov, S. A.

    2011-02-01

    This work is dedicated to spectroscopic investigations of laser spark during the laser cleaning process. The goal is to proof its analytical possibilities for chemical composition determination for online cleaning quality control. Photographic recordings of laser spark were performed to estimate its parameters. Fiber spectrometer was used to analyze the emission of cleaning process established with fiber laser. Conclusions have been made about fiber laser radiation usability for spectroscopic purpose.

  9. Bio-Inspired Self-Cleaning Surfaces

    NASA Astrophysics Data System (ADS)

    Liu, Kesong; Jiang, Lei

    2012-08-01

    Self-cleaning surfaces have drawn a lot of interest for both fundamental research and practical applications. This review focuses on the recent progress in mechanism, preparation, and application of self-cleaning surfaces. To date, self-cleaning has been demonstrated by the following four conceptual approaches: (a) TiO2-based superhydrophilic self-cleaning, (b) lotus effect self-cleaning (superhydrophobicity with a small sliding angle), (c) gecko setae-inspired self-cleaning, and (d) underwater organisms-inspired antifouling self-cleaning. Although a number of self-cleaning products have been commercialized, the remaining challenges and future outlook of self-cleaning surfaces are also briefly addressed. Through evolution, nature, which has long been a source of inspiration for scientists and engineers, has arrived at what is optimal. We hope this review will stimulate interdisciplinary collaboration among material science, chemistry, biology, physics, nanoscience, engineering, etc., which is essential for the rational design and reproducible construction of bio-inspired multifunctional self-cleaning surfaces in practical applications.

  10. EM Task 12 -- Laser cleaning of contaminated painted surfaces. Semi-annual report, April 1--September 30, 1997

    SciTech Connect

    Grisanti, A.A.; Jenson, R.R.; Allan, S.E.

    1997-12-31

    Surface decontamination of concrete and steel surfaces in nuclear facilities provides cost savings during decommissioning operations by allowing recycling or reuse of concrete and steel structures. Separation of radionuclides and other contamination from the concrete or steel substrates also allows reduction in volume of hazardous materials during the D and D (decontamination and decommissioning) process, resulting in further cost savings. Several techniques are available or under development for surface decontamination in nuclear facilities. Each technique has its merits; however, none of them is universally the best choice for all surface decontamination applications. Because of the multitude of factors which influence the environmental and economic aspects of selecting a surface decontamination technique, it is difficult to select the best method in a given situation; an objective basis for comparing techniques is needed. The objective of this project is to develop a software tool for use by personnel selecting a surface decontamination technique. The software will incorporate performance data for available surface decontamination techniques. The major activities in the project are broken down as follows: Task 1--Complete decision tree development; Task 2--Literature search for surface decontamination reports; Task 3--Compilation of database from literature data; Task 4--Sensitivity analysis and model design; Task 5--Design of model data structures; and Task 6--PC software design and coding. Work during this reporting period completed Tasks 1, 2, 3, 5, and 6. Task 4 activities resulted in a prototype of the model design; sensitivity analysis and model modifications are in progress at the time of this report. Task 4 will be complete prior to the end of December 1997. A working prototype of the software implementation of the surface decontamination model and technology database has been completed. The program developed at the Energy and Environmental Research

  11. Laser cleaning of sulfide scale on compressor impeller blade

    NASA Astrophysics Data System (ADS)

    Tang, Q. H.; Zhou, D.; Wang, Y. L.; Liu, G. F.

    2015-11-01

    Sulfide scale on the surface of a compressor impeller blade can considerably reduce the impeller performance and its service life. To prepare for subsequent remanufacturing, such as plasma spraying, it needs to be removed completely. In the corrosion process on an FV(520)B stainless steel, sulfide scale is divided into two layers because of different outward diffusion rates of Cr, Ni and Fe. In this paper, the cleaning threshold values of the upper and inner layers and the damage threshold value of the substrate were investigated using a pulsed fiber laser. To obtain experimental evidence, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and 3D surface profilometry were employed to investigate the two kinds of sulfide layers on specimens before, during, and after laser cleaning.

  12. Laser cleaning of copper roofing sheets subjected to long-lasting environmental corrosion

    NASA Astrophysics Data System (ADS)

    Garbacz, H.; Fortuna, E.; Marczak, J.; Strzelec, M.; Rycyk, A.; Koss, A.; Mróz, J.; Zatorska, A.; Kurzydłowski, K. J.

    2010-09-01

    The study was concerned with the effect of the laser fluence and pulse duration on the microstructure of copper roofing of the Wilanów Palace in Warsaw (Poland) subjected to environmental degradation since the turn 19th century. The techniques used for the microstructure examinations included: SEM+EDS, X-ray diffraction analysis, surface profiling and colour analysis. The measurements of colour of the laser-cleaned surfaces showed that series of 100-μs pulses offer the most effective cleaning. It was also found that by controlling the number of laser pulses it is possible to control the roughness of the cleaned surface.

  13. Laser cleaning of diagnostic mirrors from tungsten–oxygen tokamak-like contaminants

    NASA Astrophysics Data System (ADS)

    Maffini, A.; Uccello, A.; Dellasega, D.; Passoni, M.

    2016-08-01

    This paper presents a laboratory-scale experimental investigation about the laser cleaning of diagnostic first mirrors from tokamak-like contaminants, made of oxidized tungsten compounds with different properties and morphology. The re-deposition of contaminants sputtered from a tokamak first wall onto first mirrors’ surfaces could dramatically decrease their reflectivity in an unacceptable way for the proper functioning of plasma diagnostic systems. The laser cleaning technique has been proposed as a solution to tackle this issue. In this work, pulsed laser deposition was exploited to produce rhodium films functional as first mirrors and to deposit onto them contaminants designed to be realistic in reproducing materials expected to be re-deposited on first mirrors in a tokamak environment. The same laser system was also used to perform laser cleaning experiments, exploiting a sample handling procedure that allows one to clean some cm2 in a few minutes. Cleaning effectiveness was evaluated in terms of specular reflectance recovery and mirror surface integrity. The effect of different laser wavelengths (λ =1064 , 266 nm) on the cleaning process was also addressed, as well as the impact of multiple contamination/cleaning cycles on the process outcome. A satisfactory recovery of pristine mirror reflectance (⩾90%) was obtained in the vis–NIR spectral range, avoiding at the same time mirror damaging. The results here presented show the potential of the laser cleaning technique as an attractive solution for the cleaning of diagnostic first mirrors.

  14. Investigation of laser cleaning on bronze cultural relics

    NASA Astrophysics Data System (ADS)

    Ling, Xiulan; Wang, Gao; Zhang, Chen

    2016-05-01

    The effects of laser cleaning on the corrosion layers of bronze cultural relics were studied using a pulsed fiber laser. The laser cleaning threshold value of the corrosion layers was obtained. It was found that the corrosion layer was removed successfully by employing a laser fluence value of 0.32 J cm-2 and scanning for three times. To obtain experimental evidence, laser con-focal scanning microscopy, scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), laser induced breakdown spectroscopy (LIBS) and laser Raman spectroscopy were employed to investigate the cleaning efficiency of corrosion layers on specimens.

  15. Shear stress cleaning for surface departiculation

    NASA Technical Reports Server (NTRS)

    Musselman, R. P.; Yarbrough, T. W.

    1986-01-01

    A cleaning technique widely used by the nuclear utility industry for removal of radioactive surface contamination has proven effective at removing non-hazardous contaminant particles as small as 0.1 micrometer. The process employs a controlled high velocity liquid spray inside a vapor containment enclosure to remove particles from a surface. The viscous drag force generated by the cleaning fluid applies a shear stress greater than the adhesion force that holds small particles to a substrate. Fluid mechanics and field tests indicate general cleaning parameters.

  16. Laser cleaning of ablation debris from CO 2-laser-etched vias in polyimide

    NASA Astrophysics Data System (ADS)

    Coupland, Kristen; Herman, Peter R.; Gu, Bo

    1998-05-01

    CO 2-laser-drilled vias in polyimide-based flex circuits generate substantial surface debris, requiring new approaches to reduce or eliminate the debris and therefore do away with wet chemical or plasma cleaning steps. A dry laser cleaning process based on a wavelength-tunable CO 2 laser is shown for the first time to effectively remove the ablation debris. Other techniques based on gas flow, pressure control, or ultraviolet lasers, were found ineffective due to the presence of both massive (>10 μm) fibrous debris and submicron (<500 nm) soot. The debris-removal process is driven by disparate mechanisms. The soot is ejected in only ˜5 laser pulses by rapid thermal expansion of the laser-heated polyimide substrate. The removal of fibrous debris develops over many more pulses and involves Fresnel diffraction, surface-rippling phenomena, and multipulse ablation of the debris fragments. The fastest debris cleaning time of 2.5 s per via was provided by the 9R12 laser line at 20 Hz and 0.6 J/cm 2 fluence.

  17. Cathodic ARC surface cleaning prior to brazing

    SciTech Connect

    Dave, V. R.; Hollis, K. J.; Castro, R. G.; Smith, F. M.; Javernick, D. A.

    2002-01-01

    Surface cleanliness is one the critical process variables in vacuum furnace brazing operations. For a large number of metallic components, cleaning is usually accomplished either by water-based alkali cleaning, but may also involve acid etching or solvent cleaning / rinsing. Nickel plating may also be necessary to ensure proper wetting. All of these cleaning or plating technologies have associated waste disposal issues, and this article explores an alternative cleaning process that generates minimal waste. Cathodic arc, or reserve polarity, is well known for welding of materials with tenacious oxide layers such as aluminum alloys. In this work the reverse polarity effect is used to clean austenitic stainless steel substrates prior to brazing with Ag-28%Cu. This cleaning process is compared to acid pickling and is shown to produce similar wetting behavior as measured by dynamic contact angle experiments. Additionally, dynamic contact angle measurements with water drops are conducted to show that cathodic arc cleaning can remove organic contaminants as well. The process does have its limitations however, and alloys with high titanium and aluminum content such as nickel-based superalloys may still require plating to ensure adequate wetting.

  18. Method for cleaning and passivating a metal surface

    NASA Technical Reports Server (NTRS)

    Alexander, George B. (Inventor); Carpenter, Norman F. (Inventor)

    1976-01-01

    A cleaning solvent useful in the cleaning of metal surfaces, e.g. nickle-iron alloys, contains sulfamic acid, citric acid, a solvent for hydrocarbon residues, and a surfactant. Metal surfaces are cleaned by contacting the surface with the cleaning solvent and then passivated by contact with aqueous solutions of citric acid or sodium nitrite or a combination of the two.

  19. Photocatalytic Solutions Create Self-Cleaning Surfaces

    NASA Technical Reports Server (NTRS)

    2013-01-01

    A Stennis Space Center researcher investigating the effectiveness of photocatalytic materials for keeping the Center's buildings free of grime turned to a solution created by PURETi Inc. of New York City. Testing proved successful, and NASA and the company now share a Dual Use Technology partnership. PURETi's coatings keep surfaces clean and purify surrounding air, eliminating pollution, odors, and microbes.

  20. Surface treatments by laser

    NASA Astrophysics Data System (ADS)

    Thomann, A. L.; Benzerga, R.; Basillais, Armelle; Georges, Cecile; Fariaut, Francois; Semmar, Nadjib; Boulmer-Leborgne, Chantal

    2003-07-01

    Laser treatments of various metals are studying depending on the laser wavelength, pulse time duration and shape, and fluence (laser/metal interaction regime). Low fluence excimer UV laser melting process of gold layer is shown to improve the corrosion resistance of multilayer (Au/Ni/Cu alloy) electrical contacts. For this application the homogenity of the laser beam as well as the initial Cu substrate roughness are found to be limiting parameters of the process. Carburization of Al alloy, performed in C3H6 atmosphere with a KrF laser induces the incorporation of carbon atoms over about 4 μm depth. The crystalline Al4C3 synthesized at the surface leads to a strengthening of the light Al alloy, which is of great interest for application in car industry. The study shows that diffusion of C atom in the target is possible because of a plasma presence on the surface which supports the molten bath life time and induces dissociation of the ambient gas. In the last example of laser metal surface treatment presented in that paper, a commonly used steel is treated in air with different lasers at a fluence above the plasma formation threshold. It is seen that the machining oils covering the surface before the treatment can be efficiently removed and that new compounds (nitride, carbide and oxides) are formed at the surface.

  1. Laser cleaning of oil spill on coastal rocks

    NASA Astrophysics Data System (ADS)

    Kittiboonanan, Phumipat; Rattanarojpan, Jidapa; Ratanavis, Amarin

    2015-07-01

    In recent years, oil spills have become a significant environmental problem in Thailand. This paper presents a laser treatment for controlled-clean up oil spill from coastal rocks. The cleaning of various types of coastal rocks polluted by the spill was investigated by using a quasi CW diode laser operating at 808 nm. The laser power was attempted from 1 W to 70 W. The result is shown to lead to the laser removal of oil spill, without damaging the underlying rocks. In addition, the cleaning efficiency is evaluated using an optical microscope. This study shows that the laser technology would provide an attractive alternative to current cleaning methods to remove oil spill from coastal rocks.

  2. Behavior of Al on Clean and Oxidized GaAs(110) Surfaces

    NASA Astrophysics Data System (ADS)

    Kim, Hyunwoo

    1993-04-01

    The adsorption of Al on clean and oxidized GaAs(110) surfaces was studied. The characteristics of an oxide surface formed in vacuum and during the chemical etching process of the tip have been investigated using the field desorption (FD) cleaning method and the retarding potential analyzer (RPA) equipped with an argon laser. The results obtained for the FD clean surface and on the oxidized surface are discussed in terms of the RPA threshold and work function change. The oxide films formed at relatively low temperatures on the GaAs(110) surface can easily be desorbed by FD. The intrinsic potential drops across the oxide surface disappear suddenly at a certain field value. This may indicate that the desorbed surface region is composed of a metallic species such as Ga. Changes in work function are observed but there is no change in the threshold values (Vth) with deposition of Al on the field-desorbed clean surface. The thick layers of Al on the oxidized surface completely cancel the effect of oxide on Vth, which decreases to the value of a metallic clean surface. In addition, the value of Vth decreases dramatically to that of a metallic clean surface by absorption of the laser beam on the oxidized surface, whereas only the thermal effect is seen on a metallic clean surface.

  3. 40 CFR 761.369 - Pre-cleaning the surface.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Pre-cleaning the surface. 761.369... PROHIBITIONS Double Wash/Rinse Method for Decontaminating Non-Porous Surfaces § 761.369 Pre-cleaning the surface. If visible PCB-containing liquid is present on the surface to be cleaned, thoroughly wipe or...

  4. Aluminum Surface Texturing by Means of Laser Interference Metallurgy

    SciTech Connect

    Chen, Jian; Sabau, Adrian S; Jones, Jonaaron F.; Hackett, Alexandra C.; Daniel, Claus; Warren, Charles David

    2015-01-01

    The increasing use of lightweight materials, such as aluminum alloys, in auto body structures requires more effective surface cleaning and texturing techniques to improve the quality of the structural components. The present work introduces a novel surface treatment method using laser interferometry produced by two beams of a pulsed Nd:YAG laser operating at 10Hz of frequency to clean aluminum surfaces, and meanwhile creating periodic and rough surface structures. The influences of beam size, laser fluence, wavelength, and pulse number per spot are investigated. High resolution optical profiler images reveal the change of the peak-to-valley height on the laser-treated surface.

  5. Laser cleaning of rust on ship steel using TEA CO2 pulsed laser

    NASA Astrophysics Data System (ADS)

    Ke, Linda; Zhu, Haihong; Lei, Wenjuan; Cheng, Zuhai

    2009-08-01

    Ship is easy to rust because of its special working condition. Removal of the rust from the ship surface is generally required for maintaining ship. The feasibility of removing rust using pulsed laser has been confirmed by the past researches. However, the general utilized laser, e.g., pulsed Nd: YAG laser with narrow pulse duration and high peak power, suffers very low average power and throughput. TEA CO2 laser, which also has narrow pulse duration and high peak power, is expected to obtain high throughout because it is easy to obtain high average power. This paper investigated the feasibility and the efficiency of removal of rust from the ship steel using TEA CO2 pulsed laser. The results show that TEA CO2 pulsed laser can effectively clean the rust by using suitable parameters without damage the substrate. A cleaning threshold for stripping rust of power density exists. Also, the effect of the process parameters on the efficiency and performance as well as the removal mechanism were studied in this paper.

  6. Novel Laser Ablation Technology for Surface Decontamination

    SciTech Connect

    Cheng, Chung H.

    2004-06-01

    Laser ablation for surface cleaning has been pursued for the removal of paint on airplanes. It has also been pursued for the cleaning of semiconductor surfaces. However, all these approaches have been pursued by laser ablation in air. For highly contaminated surface, laser ablation in air can easily cause secondary contamination. Thus it is not suitable to apply to achieve surface decontamination for DOE facilities since many of these facilities have radioactive contaminants on the surface. Any secondary contamination will be a grave concern. The objective of this project is to develop a novel technology for laser ablation in liquid for surface decontamination. It aims to achieve more efficient surface decontamination without secondary contamination and to evaluate the economic feasibility for large scale surface decontamination with laser ablation in liquid. When laser ablation is pursued in the solution, all the desorbed contaminants will be confined in liquid. The contaminants can be precipitated and subsequently contained in a small volume for disposal. It can reduce the risk of the decontamination workers. It can also reduce the volume of contaminants dramatically.

  7. Critical Surface Cleaning and Verification Alternatives

    NASA Technical Reports Server (NTRS)

    Melton, Donald M.; McCool, A. (Technical Monitor)

    2000-01-01

    As a result of federal and state requirements, historical critical cleaning and verification solvents such as Freon 113, Freon TMC, and Trichloroethylene (TCE) are either highly regulated or no longer 0 C available. Interim replacements such as HCFC 225 have been qualified, however toxicity and future phase-out regulations necessitate long term solutions. The scope of this project was to qualify a safe and environmentally compliant LOX surface verification alternative to Freon 113, TCE and HCFC 225. The main effort was focused on initiating the evaluation and qualification of HCFC 225G as an alternate LOX verification solvent. The project was scoped in FY 99/00 to perform LOX compatibility, cleaning efficiency and qualification on flight hardware.

  8. Laser cleaning: an alternative method for removing oil-spill fuel residues

    NASA Astrophysics Data System (ADS)

    Mateo, M. P.; Nicolas, G.; Piñon, V.; Ramil, A.; Yañez, A.

    2005-07-01

    Cleaning methods employed in last oil spills usually require direct contact or the intervention of external agents that can lead to additional contamination and damage of treated surfaces. As an alternative, a laser-based methodology is proposed in this work for controlled removal of fuel residues caused by the accident of Prestige tanker from rocks, as well as tools and equipment employed in fuel retaining and elimination procedures. Ablation thresholds of fuel crust and underlying material have been investigated with the aim to establish operational parameters that preserve the structural integrity and identity of the latter. The clean-up process was controlled by the self-limiting nature of the process or by laser-induced plasma spectroscopy. Contaminated, no contaminated and cleaned areas of the samples have been characterized by complementary microscopy techniques to help in the task of optimizing the laser cleaning procedure and checking the effectiveness of the removal process.

  9. Novel Applications of the Er:YAG Laser Cleaning of Old Paintings

    NASA Astrophysics Data System (ADS)

    Andreotti, A.; Bracco, P.; Colombini, M. P.; deCruz, A.; Lanterna, G.; Nakahara, K.; Penaglia, F.

    This chapter focuses on the use of Er:YAG laser cleaning technique for the removal of unwanted and/or degraded materials both from a large series of reference standards (overpainting, varnishes, patinas, and restoration materials) which simulate the layering of old paintings, and also examples from old paintings. A series of diagnostic controls (optical microscopy, SEM, FT-IR, GC-MS, and topographic techniques) were designed to study the effects of the laser radiation on the surface components, including morphological, optical, and chemical examination. The most significant results show that an effective thin-layer-removal of about 90% is obtained by submitting the painted surfaces to the laser exposure, while the rest of cleaning is rapidly accomplished in safety by applying mild solvents or aqueous methods. Consequently, possible interference with the original substrate can be noticeably minimized. No degradation compound induced by laser energy was formed. The laser cleaning procedure applied on an oil painting canvas "Morte di Adone" (seventeenth century), and on a panel tempera painting "San Nicola e San Giusto" of Domenico di Michelino (fifteenth century) shows that the surfaces cleaned by this system exhibit a morphology quite similar to that obtained by traditional cleaning methods.

  10. Cleaning Of Black Crust From Marble Substrate By Short Free Running {mu}s Nd: YAG Laser

    SciTech Connect

    Khedr, A.; Harith, M. A.; Pouli, P.; Fotakis, C.

    2009-09-27

    One of the most important aspects in laser cleaning of artworks is the possibility for on-line monitoring the cleaning process. This ensures that the cleaning intervention is satisfactory without any damage to the underlying original surface. In this work it is shown that following and observing the integrated densities of the plumes generated during laser cleaning may be a simple, safe and straightforward methodology to monitor the removal process. A series of experiments on reference marble with simulated thick encrustation were considered to evaluate the plume monitoring technique. Parameters influencing the cleaning process and ablation threshold of the black crust (such as laser fluence, number of pulses etc.) were considered while the results were also evaluated under the microscope. The results of this study will be presented and discussed with the aim to establish accurate and reliable monitoring tools to follow the laser cleaning process.

  11. Surface magnetic enhancement for coal cleaning

    SciTech Connect

    Hwang, J.Y.

    1992-01-01

    The program consisted of a fundamental study to define the chemistry for the interactions between magnetic reagent and mineral and coal particles, a laboratory study to determine the applicability of this technology on coal cleaning, and a parameter study to evaluate the technical and economical feasibility of this technology for desulfurization and de-ashing under various processing schemes. Surface magnetic enhancement using magnetic reagent is a new technology developed at the Institute. This technology can be applied to separate pyrite and other minerals particles from coal with a magnetic separation after adsorbing magnetic reagent on the surface of pyrite and other minerals particles. Particles which have absorbed magnetic reagent are rendered magnetic. The adsorption can be controlled to yield selectivity. Thus, the separation of traditionally nonmagnetic materials with a magnetic separator can be achieved. Experiments have been performed to demonstrate the theoretical fundamentals and the applications of the technology. Adsorbability, adsorption mechanisms, and adsorption selectivity are included in the fundamental study. The effects of particle size, magnetic reagent dosage, solid contents, magnetic matrix, applied magnetic field strengths, retention times, and feed loading capacities are included in the application studies. Three coals, including Illinois No. 6, Lower Kittanning and Pocahontas seams, have been investigated. More than 90% pyritic sulfur and ash reductions have been achieved. Technical and economic feasibilities of this technology have been demonstrated in this study. Both are competitive to that of the froth flotation approach for coal cleaning.

  12. Directional self-cleaning superoleophobic surface.

    PubMed

    Zhao, Hong; Law, Kock-Yee

    2012-08-14

    In this work, we report the creation of a grooved surface comprising 3 μm grooves (height ~4 μm) separated by 3 μm from each other on a silicon wafer by photolithography. The grooved surface was then modified chemically with a fluorosilane layer (FOTS). The surface property was studied by both static and dynamic contact angle measurements using water, hexadecane, and a polyethylene wax ink as the probing liquids. Results show that the grooved surface is both superhydrophobic and superoleophobic. Its observed contact angles agree well with the calculated Cassie-Baxter angles. More importantly, we are able to make a replica of the composite wax ink-air interface and study it by SEM. Microscopy results not only show that the droplet of the wax ink "sits" on air in the composite interface but also further reveal that the ink drop actually pins underneath the re-entrant structure in the side wall of the grooved structure. Contact angle measurement results indicate that wetting on the grooved surface is anisotropic. Although liquid drops are found to have lower static and advancing contact angles in the parallel direction, the drops are found to be more mobile, showing smaller hysteresis and lower sliding angles (as compared to the FOTS wafer surface and a comparable 3-μm-diameter pillar array FOTS surface). The enhanced mobility is attributable to the lowering of the resistance against an advancing liquid because 50% of the advancing area is made of a solid strip where the liquid likes to wet. This also implies that the contact line for advancing is no longer smooth but rather is ragged, having the solid strip area leading the wetting and the air strip area trailing behind. This interpretation is supported by imaging the geometry of the contact lines using molten ink drops recovered from the sliding angle experiments in both the parallel and orthogonal directions. Because the grooved surface is mechanically stronger against mechanical abrasion, the self-cleaning

  13. Laser nitriding and laser carburizing of surfaces

    NASA Astrophysics Data System (ADS)

    Schaaf, Peter

    2003-11-01

    Laser irradiation of surfaces with short pulses in reactive atmospheres (nitrogen, methane) can lead to very effective nitrification and carburization via complicated laser-surface-gas-plasma-interactions. This laser nitriding and laser carburizing and their basic underlying phenomena will be presented and partly explained by results of example materials (iron, titanium, aluminum, silicon) where nitride and carbide coatings can be formed by fast and easily by Excimer Laser, Nd:YAG laser, Free Electron Laser and also by femtosecond Ti:sapphire laser. This implies laser pulse durations from the nanosecond to the femtosecond regime and wavelengths from ultra-violet to infrared. The resulting surfaces, thin films, coatings and their properties are investigated by combining Mossbauer Spectroscopy, x-ray diffraction, x-ray absorption spectroscopy, Nanoindentation, Resonant Nuclear Reaction Analysis, and Rutherford Backscattering Spectroscopy.

  14. Enhancement of airborne shock wave by laser-induced breakdown of liquid column in laser shock cleaning

    SciTech Connect

    Jang, Deoksuk; Kim, Dongsik; Park, Jin-Goo

    2011-04-01

    In laser shock cleaning (LSC), the shock wave is generated by laser-induced breakdown of the ambient gas. The shock wave intensity has thus been a factor limiting the performance of the LSC process. In this work, a novel method of amplifying a laser-induced plasma-generated shock wave by the breakdown of a liquid column is proposed and analyzed. When the laser beam is focused on a microscale liquid column, a shock wave having a significantly amplified intensity compared to that generated by air breakdown alone can be generated in air. Therefore, substantially amplified cleaning force can be obtained. The dynamics of a shock wave induced by a Q-switched Nd:YAG laser was analyzed by laser flash shadowgraphy. The peak pressure of the laser-induced shock wave was approximately two times greater than that of air breakdown at the same laser fluence. The proposed method of shock wave generation is expected to be useful in various applications of laser shock processing, including surface cleaning.

  15. Laser textured surface gradients

    NASA Astrophysics Data System (ADS)

    Ta, Van Duong; Dunn, Andrew; Wasley, Thomas J.; Li, Ji; Kay, Robert W.; Stringer, Jonathan; Smith, Patrick J.; Esenturk, Emre; Connaughton, Colm; Shephard, Jonathan D.

    2016-05-01

    This work demonstrates a novel technique for fabricating surfaces with roughness and wettability gradients and their subsequent applications for chemical sensors. Surface roughness gradients on brass sheets are obtained directly by nanosecond laser texturing. When these structured surfaces are exposed to air, their wettability decreases with time (up to 20 days) achieving both spatial and temporal wettability gradients. The surfaces are responsive to organic solvents. Contact angles of a series of dilute isopropanol solutions decay exponentially with concentration. In particular, a fall of 132° in contact angle is observed on a surface gradient, one order of magnitude higher than the 14° observed for the unprocessed surface, when the isopropanol concentration increased from 0 to 15.6 wt%. As the wettability changes gradually over the surface, contact angle also changes correspondingly. This effect offers multi-sensitivity at different zones on the surface and is useful for accurate measurement of chemical concentration.

  16. Treating the untreatable in art and heritage materials: ultrafast laser cleaning of "cloth-of-gold".

    PubMed

    Kono, Mitsuhiko; Baldwin, Kenneth G H; Wain, Alison; Rode, Andrei V

    2015-02-01

    Laser cleaning provides art and heritage conservators with an alternative means to restore objects when traditional chemical and mechanical methods are not viable. However, long (>nanosecond) laser pulses can cause unwanted damage from photothermal processes and provide limited control over ablation depth. Ultrashort (lasers are emerging as a more appropriate tool for cleaning historic artifacts because of their unique ability to avoid heat- and shock-wave generation, thus minimizing collateral damage of the underlayers, and to remove material with near-nanometer precision. Here we demonstrate the effectiveness of ultrashort pulses by cleaning 19th century military gold braid without any detrimental effects on the gold foil or the underlying silk thread structure. The results are compared with nanosecond-pulse laser treatment that damages the surface structure. By introducing in situ feedback control of the laser ablation via laser-induced breakdown spectroscopy (LIBS) monitoring of the ablated plume, we are able to halt the cleaning process just as the contaminant layer is completely removed. This technique allows ultrafast laser ablation to extend the armory of conservation treatments, enabling restoration of a range of complex and fragile heritage objects previously untreatable by conventional means. PMID:25561084

  17. Surface and electrochemical studies in coal cleaning

    SciTech Connect

    Chander, S.; Aplan, F.F.; Briceno, A.; Esposito, M.C.; Pang, J.; Raleigh, C.E.

    1989-05-01

    This final technical report, summarizes the accomplishments of our investigation on surface and electrochemical studies in coal cleaning. A considerable effort was made to characterize coal pyrites in detail. The report is divided into three self-contained portions: flotation studies, characterization of pyrite from coal sources, and electrochemical characterization of pyrite. A variety of reagents were found to be effective for the depression of pyrite during coal flotation: lime, oxidizing agents, reducing agents, polysaccharides, xanthated polysaccharides and dye. Seven pyrite samples purified from coal sources and one ore source pyrite (for comparative purposes) have been characterized by chemical and mineralogical analyses, inherent floatability, apparent specific gravity, surface area, semiconductor type, optical anisotropy, dissolution and oxidation rate. Cyclic voltammetry, steady-state polarization and AC impedance spectroscopy have been used to characterize pyrites from ore and coal sources. These studies show that one reason for difference in the behavior of pyrites is the nature of surface films that form when pyrite oxidizes. 85 refs., 29 figs., 15 tabs.

  18. Spectroscopic Monitoring of the Laser Cleaning Applied to Ancient Marbles from Mediterranean Areas

    NASA Astrophysics Data System (ADS)

    Lazic, V.; Colao, F.; Fantoni, R.; Fiorani, L.; Palucci, A.; Striber, J.; Santagata, A.; Morone, A.; Spizzicchino, V.

    Laser Induced Breakdown Spectroscopy (LIBS) analysis by Nd:YAG laser emitting at 355nm were performed on different clean and dirty surfaces of marble fragments collected from ancient quarries in Greece, Turkey and Italy, in order to determine semi-quantitavely the atomic composition of the bulk material and encrustation. The method here developed for element concentrations retrieval could be applied during laser cleaning process to supply the information about the effective crust composition at different depths and the point where the process should be interrupted. The knowledge of the crust composition along successive layers is also important for determining the restoration procedures. The elements measured in the encrustations, such as Si, Al, Ca, C, Ti, Mn, Mg, Na, Ba, Sr and Cu are also present in the bulk, but at different concentrations whose determination allows for the process monitoring. The only element here observed in the crusts and not detected in the bulk materials is Chromium, whose progressive disappearance from LIBS spectra could be used as another indicator of the laser cleaning effectiveness. On a sample from Turkey also Vanadium was detected in the encrustation. The present LIBS measuring method was validated by SEM-EDX and ICP analyses. The clean marble surface and encrustations were further analysed by Laser Induced Fluorescence (LIF), which could be used as an alternative technique for the on-line control of the cleaning effectiveness. Better discrimination between dirty and clean marble surface was obtained when 266nm excitation was applied instead of 355 nm. Characteristic LIF spectral signatures allows for the discrimination between different type of the natural stones, even under the water.

  19. SURFACTANT ENHANCEMENT OF LIQUID CO2 FOR SURFACE CLEANING

    EPA Science Inventory

    The goal of this research activity is to develop the technical basis for a liquid CO2 (LCO2) based surface cleaning technology for metals and fabrics utilizing CO2 compatible surfactants. The use of CO2 is considered attractive for surface cleaning since it is abundant, cheap t...

  20. Spatial mode cleaning in radically asymmetric strongly focused laser beams

    NASA Astrophysics Data System (ADS)

    Heins, Alan M.; Guo, Chunlei

    2013-12-01

    We demonstrate that a femtosecond laser pulse strongly focused in air can produce a highly symmetric damage pattern on glass. This damage pattern contains a series of near-perfect radial rings, with diameters much larger than the predicted focal spot diameter. These rings disappear when the experiment is conducted in vacuum, indicating atmospheric involvement. Surprisingly, the shape and size of the rings seem to be nearly independent of the shape of the generating laser beam, showing dramatic spatial mode cleaning. A "half moon" initial laser mode created by obscuring one side of the round beam produces rings of similar quality to those obtained with the unclipped beam. While spatial mode cleaning has previously been reported in filaments, this is the most dramatic demonstration of the effect that we are aware of. We argue that the effect is due primarily to ionization, in contrast to studies in longer filaments that attribute it to self-focusing.

  1. Investigation of aluminum surface cleaning using cavitating fluid flow

    NASA Astrophysics Data System (ADS)

    Ralys, Aurimas; Striška, Vytautas; Mokšin, Vadim

    2013-12-01

    This paper investigates efficiency of specially designed atomizer used to spray water and cavitate microbubbles in water flow. Surface cleaning system was used to clean machined (grinded) aluminum surface from abrasive particles. It is established that cleaning efficiency depends on diameter of the diffuser, water pressure and distance between nozzle and metal surface. It is obtained that the best cleaning efficiency (100%) is achieved at pressure 36 bar, when diameter of diffuser is 0.4 mm and distance between nozzle and surface is 1 mm. It is also established that satisfactory cleaning efficiency (80%) is achieved not only when atomizer is placed closer to metal surface, but also at larger (120 mm) distances.

  2. Effect of different provisional cement remnant cleaning procedures including Er:YAG laser on shear bond strength of ceramics

    PubMed Central

    Zortuk, Mustafa; Gumus, Hasan Onder; Kilinc, Halil Ibrahim

    2012-01-01

    PURPOSE The purpose of this study was to evaluate the effect of provisional cement removal by different dentin cleaning protocols (dental explorer, pumice, cleaning bur, Er:YAG laser) on the shear bond strength between ceramic and dentin. MATERIALS AND METHODS In total, 36 caries-free unrestored human third molars were selected as tooth specimens. Provisional restorations were fabricated and cemented with eugenol-free provisional cement. Then, disc-shaped ceramic specimens were fabricated and randomly assigned to four groups of dentin cleaning protocols (n = 9). Group 1 (control): Provisional cements were mechanically removed with a dental explorer. Group 2: The dentin surfaces were treated with a cleaning brush with pumice Group 3: The dentin surfaces were treated with a cleaning bur. Group 4: The provisional cements were removed by an Er:YAG laser. Self-adhesive luting cement was used to bond ceramic discs to dentin surfaces. Shear bond strength (SBS) was measured using a universal testing machine at a 0.05 mm/min crosshead speed. The data were analyzed using a Kolmogorov Smirnov, One-way ANOVA and Tukey HSD tests to perform multiple comparisons (α=0.05). RESULTS The dentin cleaning methods did not significantly affect the SBS of ceramic discs to dentin as follows: dental explorer, pumice, cleaning bur, and Er:YAG laser. CONCLUSION The use of different cleaning protocols did not affect the SBS between dentin and ceramic surfaces. PMID:23236570

  3. Evaluating the use of laser radiation in cleaning of copper embroidery threads on archaeological Egyptian textiles

    NASA Astrophysics Data System (ADS)

    Abdel-Kareem, Omar; Harith, M. A.

    2008-07-01

    Cleaning of copper embroidery threads on archaeological textiles is still a complicated conservation process, as most textile conservators believe that the advantages of using traditional cleaning techniques are less than their disadvantages. In this study, the uses of laser cleaning method and two modified recipes of wet cleaning methods were evaluated for cleaning of the corroded archaeological Egyptian copper embroidery threads on an archaeological Egyptian textile fabric. Some corroded copper thread samples were cleaned using modified recipes of wet cleaning method; other corroded copper thread samples were cleaned with Q-switched Nd:YAG laser radiation of wavelength 532 nm. All tested metal thread samples before and after cleaning were investigated using a light microscope and a scanning electron microscope with an energy dispersive X-ray analysis unit. Also the laser-induced breakdown spectroscopy (LIBS) technique was used for the elemental analysis of laser-cleaned samples to follow up the laser cleaning procedure. The results show that laser cleaning is the most effective method among all tested methods in the cleaning of corroded copper threads. It can be used safely in removing the corrosion products without any damage to both metal strips and fibrous core. The tested laser cleaning technique has solved the problems caused by other traditional cleaning techniques that are commonly used in the cleaning of metal threads on museum textiles.

  4. Cleanliness audit of clinical surfaces and equipment: who cleans what?

    PubMed

    Anderson, R E; Young, V; Stewart, M; Robertson, C; Dancer, S J

    2011-07-01

    Current guidelines recommend regular cleaning of clinical equipment. We monitored items on a surgical ward for predominant user, hand-touch frequency, cleaning responsibilities and measurement of organic soil. Equipment was assessed in triplicate against a cleanliness benchmark of 100 relative light units (RLU) using the Hygiena® ATP system. There were 44 items, of which 21 were cleaned by clinical support workers (CSWs), five by domestic staff; three by nurses, three by doctors, and 12 with no designated cleaning responsibility. Geometric mean RLUs ranged from 60 to 550/100 cm² for small items such as hand-gel containers, bed control, blood pressure cuff and clinical notes; with similar values of 80-540/100 cm² RLU for larger items such as electrocardiogram machine, defibrillator, trolleys and tables. Overall geometric mean was 249/100 cm² RLU for all surfaces, with 84% (37 of 44) items exceeding the 100RLU benchmark. Of 27 items cleaned by clinical staff, 24 (89%) failed the benchmark. Of 12 sites with no cleaning specification, 11 (92%) failed the benchmark. Three of seven 'clean' sites (<100/100 cm² RLU) were cleaned by domestic staff. Average log(10) RLU of surfaces cleaned by domestics were 64% lower compared with surfaces cleaned by CSWs (95% confidence interval: 35%, 80%; P=0.019). In conclusion, clinical equipment frequently demonstrates high levels of organic soil, whether or not items have assigned cleaning responsibility. These findings suggest that cleaning practices for clinical equipment may require review, along with education of staff with specific cleaning responsibilities. PMID:21497943

  5. Environmentally Clean Mitigation of Undesirable Plant Life Using Lasers

    SciTech Connect

    Rubenchik, A M; McGrann, T J; Yamamoto, R M; Parker, J M

    2009-07-01

    This concept comprises a method for environmentally clean destruction of undesirable plant life using visible or infrared radiation. We believe that during the blossom stage, plant life is very sensitive to electromagnetic radiation, with an enhanced sensitivity to specific spectral ranges. Small doses of irradiation can arrest further plant growth, cause flower destruction or promote plant death. Surrounding plants, which are not in the blossoming stage, should not be affected. Our proposed mechanism to initiate this effect is radiation produced by a laser. Tender parts of the blossom possess enhanced absorptivity in some spectral ranges. This absorption can increase the local tissue temperature by several degrees, which is sufficient to induce bio-tissue damage. In some instances, the radiation may actually stimulate plant growth, as an alternative for use in increased crop production. This would be dependent on factors such as plant type, the wavelength of the laser radiation being used and the amount of the radiation dose. Practical, economically viable realization of this concept is possible today with the advent of high efficiency, compact and powerful laser diodes. The laser diodes provide an efficient, environmentally clean source of radiation at a variety of power levels and radiation wavelengths. Figure 1 shows the overall concept, with the laser diodes mounted on a movable platform, traversing and directing the laser radiation over a field of opium poppies.

  6. Experimental study on the effect of wavelength and fluence in the laser cleaning of silvering in late Roman coins (Mid 3rd/4th century AD)

    NASA Astrophysics Data System (ADS)

    Vlachou-Mogire, C.; Drakaki, E.; Serafetinides, A. A.; Zergioti, I.; Boukos, N.

    2007-03-01

    The political problems in Late Roman Empire caused significant changes in the coin technology. The silver content dropped severely and a new technology, in all the mints operating around the Empire, was introduced. For the production of these coins, copper based quaternary alloys were used and their surface was covered by a silver amalgam plating layer. Hoards of these coins have been recovered in thousands from across the Empire, however, their treatment has been problematic. Both mechanical and chemical cleaning results in the damage or the complete destruction of the thin silver layer. The use of laser technology in the cleaning of works of art has a wide range of applications which includes metallic objects. The main aim of this work was to investigate the use of lasers in the cleaning of the thin silver plating layers found in late Roman coins. The optimisation of laser parameters was achieved through comparative cleaning tests by employing Nd:YAG (532 nm and 266 nm) laser systems. The cleaning results on the plated areas were characterised by optical microscopy, and SEM-EDX analysis. Following a systematic investigation and many cleaning trials on two different wavelengths and fluence values, optimum irradiation parameters were thoroughly demonstrated. Microscopic observations of the cleaned areas evidenced complete removal of the encrustation and high selectivity of the laser cleaning. Neither thermal or mechanical injuries, nor cuprite blackening were observed on the cleaned surfaces at the optimum laser cleaning technique, using 532 nm of the Nd: YAG laser.

  7. Laser Cleaning of Peristyle in Diocletian Palace in Split (HR)

    NASA Astrophysics Data System (ADS)

    Almesberger, D.; Rizzo, A.; Zanini, A.; Geometrante, R.

    Before starting the cleaning program of the peristyle of Diocletian Palace in Split, a series of tests have been performed on it. First of all, the state of conservation of columns and capitals has been assessed applying non-destructive techniques such as thermography, magnetoscopy and superficial ultrasonic tests. All the areas with black crusts, exfoliation and stone cracks have been determined. In this stage, parameters such as water absorption and colour have been estimated in order to compare them with those measured after the cleaning operation. Then, more than 3-month period of tests have been performed to set up all the parameters concerning the application of the laser cleaning techniques. In this chapter, the results of these preliminary investigations are presented.

  8. EUV mask surface cleaning effects on lithography process performance

    SciTech Connect

    George, Simi; Baclea-an, Lorie Mae; Naulleau, Patrick; Chen, Robert J.; Liang, Ted

    2010-06-18

    The reflective, multilayer based, mask architectures for extreme ultraviolet (EUV) lithography are highly susceptible to surface oxidation and contamination. As a result, EUV masks are expected to undergo cleaning processes in order to maintain the lifetimes necessary for high volume manufacturing. For this study, the impact of repetitive cleaning of EUV masks on imaging performance was evaluated. Two, high quality industry standard, EUV masks are used for this study with one of the masks undergoing repeated cleaning and the other one kept as a reference. Lithographic performance, in terms of process window analysis and line edge roughness, was monitored after every two cleans and compared to the reference mask performance. After 8x clean, minimal degradation is observed. The cleaning cycles will be continued until significant loss imaging fidelity is found.

  9. IV INTERNATIONAL CONFERENCE ON ATOM AND MOLECULAR PULSED LASERS (AMPL'99): Surface oxide removal by a XeCl laser for decontamination

    NASA Astrophysics Data System (ADS)

    Sentis, M. L.; Delaporte, Ph; Marine, W.; Uteza, O.

    2000-06-01

    The laser ablation performed with an automated excimer XeCl laser unit is used for large surface cleaning. The study focuses on metal surfaces that are oxidised and are representative of contaminated surfaces with radionuclides in a context of nuclear power plant maintenance. The unit contains an XeCl laser, the beam delivery system, the particle collection cell, and the system for real-time control of cleaning processes. The interaction of laser radiation with a surface is considered, in particular, the surface damage caused by cleaning radiation. The beam delivery system consists of an optical fibre bundle of 5 m long and allows delivering 150 W at 308 nm for laser surface cleaning. The cleaning process is controlled by analysing in real time the plasma electric field evolution. The system permits the cleaning of 2 to 6 m2 h-1 of oxides with only slight substrate modifications.

  10. Pedestal cleaning for high laser pulse contrast ratio with a 100 TW class laser system.

    PubMed

    Fourmaux, S; Payeur, S; Buffechoux, S; Lassonde, P; St-Pierre, C; Martin, F; Kieffer, J C

    2011-04-25

    Laser matter interaction at relativistic intensities using 100 TW class laser systems or higher is becoming more and more widespread. One of the critical issues of such laser systems is to let the laser pulse interact at high intensity with the solid target and avoid any pre-plasma. Thus, a high Laser Pulse Contrast Ratio (LPCR) parameter is of prime importance. We present the LPCR characterization of a high repetition 100 TW class laser system. We demonstrate that the generated Amplified Spontaneous Emission (ASE) degrades the overall LPCR performance. We propose a simple way to clean the pulse after the first amplification stage by introducing a solid state saturable absorber which results in a LPCR improvement to better than 10(10) with only a 30% energy loss at a 10 Hz repetition rate. We finally correlated this cleaning method with experimental results. PMID:21643098

  11. Laser Cleaning of Polyurethane Foam: An Investigation using Three Variants of Commercial PU Products

    NASA Astrophysics Data System (ADS)

    Dinesen, U. Staal; Westergaard, M.

    In this study, tests were undertaken to ascertain whether the laser could achieve a better level of cleaning on polyurethane foam than vacuum cleaning. Optimum laser parameters were found using statistics on data from color measurements. The laser proved to be very effective regarding the removal of dust, but also caused damage on some PU-variants. The laser cleaning has been carried out at National Workshops for Arts and Crafts, Copenhagen, Denmark.

  12. Optical cell cleaning with NIR femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Uchugonova, Aisada; Breunig, Hans Georg; Batista, Ana; König, Karsten

    2015-03-01

    Femtosecond laser microscopes have been used as both micro and nanosurgery tools. The optical knock-out of undesired cells in multiplex cell clusters shall be further reported on in this study. Femtosecond laser-induced cell death is beneficial due to the reduced collateral side effects and therefore can be used to selectively destroy target cells within monolayers, as well as within 3D tissues, all the while preserving cells of interest. This is an important characteristic for the application in stem cell research and cancer treatment. Non-precise damage compromises the viability of neighboring cells by inducing side effects such as stress to the cells surrounding the target due to the changes in the microenvironment, resulting from both the laser and laser-exposed cells. In this study, optimum laser parameters for optical cleaning by isolating single cells and cell colonies are exploited through the use of automated software control. Physiological equilibrium and cellular responses to the laser induced damages are also investigated. Cell death dependence on laser focus, determination and selectivity of intensity/dosage, controllable damage and cell recovery mechanisms are discussed.

  13. Laser heterodyne surface profiler

    DOEpatents

    Sommargren, Gary E.

    1984-01-01

    Method and apparatus for testing the deviation of the face of an object from a flat smooth surface using a laser beam having two plane-polarized components, one of a frequency greater than the other to produce a difference frequency with a phase to be used as a reference. The beam also is split into its two components which are directed onto spaced apart points on the face of the object. The object is rotated on an axis coincident with one component as a reference. The other component follows a circular track on the face of the object as the object is rotated. The two components are recombined after reflection to produce a difference frequency having a phase that is shifted in an amount that is proportional to the difference in path length as compared to the reference phase to produce an electrical output signal proportional to the deviation of the height of the surface along the circular track. The output signal is generated by means of a phase detector that includes a first photodetector in the path of the recombined components and a second photodetector in the path of the reference phase. The output signal is dependent on the phase difference of the two photodetector signals. A polarizer, a quarter-wave plate and a half-wave plate are in series in the path of the reference phase. Rotation of the half-wave plate can be used for phase adjustment over a full 360.degree. range for initial calibration of the apparatus.

  14. Laser-jet method of cleaning debris from space

    SciTech Connect

    Kuznetsov, L.I.; Yarygin, V.N.

    1994-12-31

    The material evaporation under laser radiation is followed by the erosion plume formation generating a momentum transfer on the irradiated surface. Such a laser jet engine, formed on small-sized space debris within the laser effect area, allows the alteration of the velocity of debris, transferring them to lower orbits where they burn up completely in the upper atmosphere. This is done with comparatively low power requirements.

  15. Surface treatment of metals with excimer and CO2 lasers

    NASA Astrophysics Data System (ADS)

    Haidemenopoulos, G. N.; Zervaki, A.; Papadimitriou, K.; Tsipas, D. N.; McIntosh, J.; Zergioti, G.; Manousaki, G.; Hontzopoulos, Elias I.

    1993-05-01

    The availability of a variety of lasers including the high-power cw CO2 lasers, the pulsed- mode infrared Nd-YAG, and the pulsed-mode ultraviolet excimer laser has led to the development of many interesting applications of laser technology to materials processing. Among them the surface modification of metallic alloys appears to be one of the most important and very close to implementation in various industries. Specifically the applications of excimer lasers have been discussed in a recent workshop in the framework of the Eureka EU 205 program. The major topics concerned with surface modifications that were discussed in this workshop were surface smoothing and roughening, surface cleaning of Ti and Cu, mixing and interdiffusion of predeposited layers, surface irradiation of Cu-alloys to improve the corrosion resistance, surface remelting of Al-alloys for grain refinement through rapid solidification, and surface remelting of Ni-P electroless coatings on Al alloys for the improvement of corrosion resistance. Laser alloying of Ni-base superalloys has also been discussed. Applications discussed here include the surface treatment of Ni-base superalloys with high-power CO2 laser, the surface treatment of aluminum alloys with excimer lasers, the laser assisted chemical vapor deposition (LCVD) of wear and corrosion resistant layers of Ti, TiC, and TiN on tool steels, and the fracture surface sulphur printing with excimer lasers.

  16. CO2 laser cleaning of black deposits formed during the excimer laser etching of polyimide in air

    NASA Astrophysics Data System (ADS)

    Koren, G.; Donelon, J. J.

    1988-01-01

    Pulsed CO2 laser cleaning of black debris formed during the excimer laser ablation of polyimide in air is demonstrated. The 10.6 μm CO2 laser radiation is strongly absorbed in the debris but only weakly absorbed in polyimide thus enabling the clean removal of the debris without damaging the polyimide.

  17. Laser carbonitriding of alumina surface

    NASA Astrophysics Data System (ADS)

    Yilbas, B. S.; Akhtar, S. S.; Karatas, C.

    2011-03-01

    Laser carbonitriding of alumina surfaces is examined. Temperature and stress fields developed during the laser heating of the substrate surface are predicted using the finite element method in line with the experimental conditions. The formation of Al(C, N) and AlN compounds in the surface region of irradiated workpiece is examined using X-ray Photoelectron Spectroscopy (XPS) and X-ray Diffraction (XRD). The microstructural and morphological changes in the laser irradiated region are examined using Scanning Electron Microscope (SEM). The microhardness of the resulting surface is measured and compared with the base material hardness. It is found that high temperature gradient is developed in the irradiated region, which in turn, results in high residual stress levels in this region. XPS and XRD data reveal the presence of Al (C, N) and AlN compounds in the surface region. The microhardness in the surface region of the laser treated workpiece increases significantly.

  18. Enamel Surface Roughness after Debonding of Orthodontic Brackets and Various Clean-Up Techniques

    PubMed Central

    Ahrari, Farzaneh; Akbari, Majid; Akbari, Javad; Dabiri, Ghahraman

    2013-01-01

    Objective: This study aimed to evaluate enamel roughness after adhesive removal using different burs and an Er:YAG laser. Materials and Methods: The buccal surfaces of forty human premolars were sealed by two layers of nail varnish, except for a circular area of 3 mm in diameter on the middle third. The enamel surfaces were initially subjected to profilometry analysis and four parameters of surface irregularity (Ra, Rq, Rt and Rz) were recorded. Following bracket bonding and debonding, adhesive remnants were removed by tungsten carbide burs in low- or high- speed handpieces (group 1 and 2, respectively), an ultrafine diamond bur (group 3) or an Er:YAG laser (250 mJ, long pulse, 4 Hz) (group 4), and surface roughness parameters were measured again. Then, the buccal surfaces were polished and the third profilometry measurements were performed. Results: The specimens that were cleaned with a low speed tungsten carbide bur showed no significant difference in surface irregularity between the different treatment stages (p>0.05). Surface roughness increased significantly after clean-up with the diamond bur and the Er:YAG laser (p<0.01). In comparison between groups, adhesive removal with tungsten carbide burs at slow- or high-speed handpieces produced the lowest, while enamel clean-up with the Er:YAG laser caused the highest values of roughness measurements (P<0.05). Conclusion: Under the study conditions, application of the ultrafine diamond bur or the Er:YAG laser caused irreversible enamel damage on tooth surface, and thus these methods could not be recommended for removing adhesive remnants after debonding of orthodontic brackets. PMID:23724206

  19. Laser heterodyne surface profiler

    DOEpatents

    Sommargren, G.E.

    1984-06-26

    Method and apparatus are disclosed for testing the deviation of the face of an object from a flat smooth surface using a laser beam having two plane-polarized components, one of a frequency greater than the other to produce a difference frequency with a phase to be used as a reference. The beam also is split into its two components which are directed onto spaced apart points on the face of the object. The object is rotated on an axis coincident with one component as a reference. The other component follows a circular track on the face of the object as the object is rotated. The two components are recombined after reflection to produce a difference frequency having a phase that is shifted in an amount that is proportional to the difference in path length as compared to the reference phase to produce an electrical output signal proportional to the deviation of the height of the surface along the circular track. The output signal is generated by means of a phase detector that includes a first photodetector in the path of the recombined components and a second photodetector in the path of the reference phase. The output signal is dependent on the phase difference of the two photodetector signals. A polarizer, a quarter-wave plate and a half-wave plate are in series in the path of the reference phase. Rotation of the half-wave plate can be used for phase adjustment over a full 360[degree] range for initial calibration of the apparatus. 12 figs.

  20. Monitoring laser cleaning of titanium alloys by probe beam reflection and emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Whitehead, D. J.; Crouse, P. L.; Schmidt, M. J. J.; Li, L.; Turner, M. W.; Smith, A. J. E.

    2008-10-01

    Studies have shown excimer laser cleaning to be an effective non-chemical alternative method for removing contaminants from surfaces of titanium alloys in preparation for electron beam welding and diffusion bonding, with reference to aerospace applications. Among several important criteria for process acceptability, is the absence of oxide formation. This paper investigates the viability of using a probe beam reflection (PBR) system and laser plume emission spectroscopy (PES) for detection of incipient oxide formation on three typical aerospace titanium alloys, viz. Ti64, Ti6246, and IMI834. These diagnostic techniques have been shown to be capable of sensing different components in the emission plume and yield quantitative results. Results from this work correlate closely with previously reported cleaning mechanisms. The oxidation threshold, as well as the operating window for successful decontamination, is discussed.

  1. Critical evaluation of current cleaning protocols for foraminiferal trace metal analyses using single shell Laser-Ablation -ICP measurements

    NASA Astrophysics Data System (ADS)

    Sadekov, A.; Eggins, S. M.; Misra, S.; Kerr, J.; Greaves, M.; Elderfield, H.

    2012-12-01

    Trace element compositions of foraminiferal calcite have been widely used as proxies for past ocean conditions. However, it has been shown that the presence of detrital material, particulate organic matter and diagenically-precipitated overgrowth on test surfaces significantly limit the accuracy of trace element analyses. A number of cleaning methods had been proposed to remove impurities from foraminiferal calcite but their relative effectiveness for foraminiferal trace metal analyses is still debatable. In this work, we employed the microanalytical technique Laser Ablation ICP-MS to compare the most commonly-used cleaning protocols. Distribution of Ca, Mg, Mn, Zn, Ba, Sr, Li, B, Fe, Al across tests of Orbulina universa from modern and Holocene sediments were analysed before and after each cleaning step. The use of Laser Ablation ICP-MS provides accurate and direct comparison of the effectiveness of each cleaning protocol, which was applied to fragments of a single foraminifera test. We also present results obtained using a novel automated cleaning device, "fOraccle", for cleaning single shell and bulk foraminiferal samples. This instrument minimises manual handling of chemical reagents during cleaning, thereby improving reproducibility of the Me/Ca measurements. Based on these results, we will discuss the composition of surface contamination on foraminiferal tests as well as possible ways to improve current cleaning protocols.

  2. Polished substrate surface and cleaning study for coated optic quality

    SciTech Connect

    Tesar, A.; Eickelberg, W.; Koons, K.; Davis, K.

    1992-11-01

    The optical substrate-coating interface is established by (1) the original polished condition of the substrate; (2) the substrate cleaning process; and (3) the environment of the coating process. The substrate-coating interface affects the coating adhesion properties, is where most coating defects and scatter sites are thought to initiate, and in some instances may control the structure of the coating as it is deposited. Often features appear on an optic after coating which could not be observed after cleaning and prior to coating. Because of the wide variety of possible substrate materials, surface problems, and contaminants, cleaning processes are constantly evolving. Our study has clearly shown that the coating appearance is dependent not only on the cleaning method, but especially on the initial character of the substrate surface.

  3. Nonhazardous solvent composition and method for cleaning metal surfaces

    DOEpatents

    Googin, John M.; Simandl, Ronald F.; Thompson, Lisa M.

    1993-01-01

    A solvent composition for displacing greasy and oily contaminants as well as water and/or aqueous residue from metallic surfaces, especially surfaces of radioactive materials so that such surfaces can be wiped clean of the displaced contaminants, water and/or aqueous residue. The solvent composition consists essentially of a blend of nonpolar aliphatic hydrocarbon solvent having a minimum flash point of about 140.degree. F. and 2 to 25 volume percent of a polar solvent having a flash point sufficiently high so as to provide the solvent composition with a minimum flash point of at least 140.degree. F. The solvent composition is nonhazardous so that when it is used to clean the surfaces of radioactive materials the waste in the form of paper or cloth wipes, lab coats and the like used in the cleaning operation is not considered to be mixed waste composed of a hazardous solvent and a radioactive material.

  4. Nonhazardous solvent composition and method for cleaning metal surfaces

    DOEpatents

    Googin, J.M.; Simandl, R.F.; Thompson, L.M.

    1993-05-04

    A solvent composition for displacing greasy and oily contaminants as well as water and/or aqueous residue from metallic surfaces, especially surfaces of radioactive materials so that such surfaces can be wiped clean of the displaced contaminants, water and/or aqueous residue. The solvent composition consists essentially of a blend of nonpolar aliphatic hydrocarbon solvent having a minimum flash point of about 140 F and 2 to 25 volume percent of a polar solvent having a flash point sufficiently high so as to provide the solvent composition with a minimum flash point of at least 140 F. The solvent composition is nonhazardous so that when it is used to clean the surfaces of radioactive materials the waste in the form of paper or cloth wipes, lab coats and the like used in the cleaning operation is not considered to be mixed waste composed of a hazardous solvent and a radioactive material.

  5. Indium phosphide negative electron affinity photocathodes: Surface cleaning and activation

    NASA Astrophysics Data System (ADS)

    Sun, Yun

    InP(100) is a very important semi-conductor for many applications. When activated by Cs and oxygen, the InP surface achieves the state of Negative Electron Affinity (NEA) making the Cs+O/InP system a very efficient electron source. Despite many years of study, the chemical cleaning and activation of InP are still not well understood. In our work, we have established an understanding of the basic physics and chemistry for the chemical cleaning and activation of the InP(100) surface. Synchrotron Radiation Photoelectron Spectroscopy is the main technique used in this study because of its high surface sensitivity and ability to identify chemical species present on the surface at each stage of our process. A clean, stoichiometric InP(100) surface is crucial for obtaining high performance of NEA photocathodes. Therefore, the first part of our study focused on the chemical cleaning of InP(100). We found that hydrogen peroxide based solutions alone, originally developed to clean GaAs(100) surfaces and widely used for InP(100), do not result in clean InP(I00) surfaces because oxide is left on the surface. A second cleaning step, which uses acid solutions like HCl or H2SO4, can remove all the oxide and leave a 0.4 ML protective layer of elemental phosphorous on the surface. The elemental phosphorous can be removed by annealing at 330°C and a clean InP(100) surface can be obtained. Cs deposition on InP(100) surface shows clear charge transfer from the Cs ad-atoms to the substrate. When the Cs/InP(100) surface is dosed with oxygen, the charge transfer from the Cs to substrate is reduced and substrate is oxidized. The activation of InP as a NEA photocathode is carried out by an alternating series of steps consisting of Cs deposition and Cs+O co-deposition. Two types of oxygen are found after activation. The first is dissociated oxygen and the other is a di-oxygen species (peroxide or superoxide). The decay of quantum-yield with time and with annealing is studied and changes in

  6. Reduction of trapped-ion anomalous heating by in situ surface plasma cleaning

    NASA Astrophysics Data System (ADS)

    McConnell, Robert; Bruzewicz, Colin; Chiaverini, John; Sage, Jeremy

    2015-08-01

    Anomalous motional heating is a major obstacle to scalable quantum information processing with trapped ions. Although the source of this heating is not yet understood, several previous studies suggest that noise due to surface contaminants is the limiting heating mechanism in some instances. We demonstrate an improvement by a factor of 4 in the room-temperature heating rate of a niobium surface electrode trap by in situ plasma cleaning of the trap surface. This surface treatment was performed with a simple homebuilt coil assembly and commercially available matching network and is considerably gentler than other treatments, such as ion milling or laser cleaning, that have previously been shown to improve ion heating rates. We do not see an improvement in the heating rate when the trap is operated at cryogenic temperatures, pointing to a role of thermally activated surface contaminants in motional heating whose activity may freeze out at low temperatures.

  7. Rapid screening of surfactant and biosurfactant surface cleaning performance.

    PubMed

    Onaizi, Sagheer A; He, Lizhong; Middelberg, Anton P J

    2009-08-01

    Surface Plasmon Resonance (SPR) and rubisco protein stain were used as tools to screen the effectiveness of detergent formulations in cleaning a protein stain from solid surfaces. Surfactant and biosurfactant-based formulations, with and without added protease, were screened for cleaning performance. Enzyme-free detergent formulations at 1500 ppm total surfactant were insufficient to cause complete surface cleaning, despite the high concentration of surfactant. The cleaning performance of a "home-made" formulation containing 2 ppm subtilisin A (SA) and 2 ppm sodium dodecyl benzyl sulphonate (SDOBS) was as efficient as the best amongst the three enzyme-free 1500 ppm formulations. The cleaning performance of 2 ppm SA in the absence of SDOBS was less effective than the combined formulation, even though 2 ppm SDOBS alone did not cause any protein removal. The observed synergistic performance was attributed to the cooperative mechanisms (chemical and physical attack) by which these two agents act on a rubisco stain. Replacing SDOBS in the enzyme-surfactant formulation with the same amount of surfactin biosurfactant (2 ppm) gave the best rubisco removal of all formulations examined in this study, irrespective of the surface chemistry underlying the protein film. It was found that 75% and 80% of immobilised rubisco stain could be removed from hydrophobic and hydrophilic surfaces, respectively, by the biosurfactant-SA formulation (compared with 60% and 65%, respectively, using the SDOBS-SA formulation). Our results suggest that it may be possible to generate fully renewable biochemical-based cleaning formulations that have superior cleaning performance to existing technologies. In developing optimised formulations, there is a pressing need for chip-based tools similar to that developed in this research. PMID:19394206

  8. Characterization of Thermal Sprayed Aluminum and Stainless Steel Coatings for Clean Laser Enclosures

    SciTech Connect

    Chow, R; Decker, T A; Gansert, R V; Gansert, D

    2000-04-06

    Surfaces of steel structures that enclose high-fluence, large-beam lasers have conventional and unconventional requirements. Aside from rust prevention, the surfaces must resist laser-induced degradation and the contamination of the optical components. The latter requires a surface that can be precision cleaned to low levels of particulate and organic residue. In addition, the surface treatment for the walls should be economical to apply because of the large surface areas involved, and accommodating with intricate joint geometries. Thermal sprayed coatings of aluminum (Al) and stainless steel are candidate surface materials. Coatings are produced and characterized for porosity, smoothness, and hardness. These properties have a bearing on the cleanliness of the coating. The laser resistance of Al and 3 16L coatings are given. The paper summarizes the characterization of twin-wire-arc deposited Al, high-velocity-oxygen-fueled (HVOF) deposited Al, flame-sprayed 316L, and HVOF deposited316L. The most promising candidate coating is that of HVOF Al. This Al coating has the lowest porosity (8%) compared the other three coatings and relatively low hardness (100 VHN). The as-deposited roughness (Ra) is 433 pinches, but after a quick sanding by hand, the roughness decreased to 166 pinches. Other post-coat treatments are discussed. HVOF aluminum coatings are demonstrated. Al coatings are corrosion barriers for steel, and this work shows promising resistance to laser damage and low particulation rates.

  9. High-Power Ultrasound in Surface Cleaning and Decontamination

    NASA Astrophysics Data System (ADS)

    Awad, Sami B.

    High-power ultrasound is being widely utilized for decontamination in different industrial applications. The same technology is also being investigated as an effective tool for cleaning of components in the decontamination of produce. An understanding of the basic technology and how it works in cleaning various industrial parts should help in applying it on a large scale in the food industry. The technology has evolved throughout the past four decades. Different frequencies were developed and are now industrially available. The frequency range is from 20 kHz to 1 MHz. Current sound technology provides a uniform ultrasonic activity throughout the cleaning vessel, which was a major disadvantage in the earlier technology. The two main driving forces that affect cleaning of surfaces are cavitation and acoustic streaming. Both are generated as a result of the direct interaction of high-frequency sound waves with fluids.

  10. SnTe microcrystals: Surface cleaning of a topological crystalline insulator

    NASA Astrophysics Data System (ADS)

    Saghir, M.; Walker, M.; McConville, C. F.; Balakrishnan, G.

    2016-02-01

    Investigating nanometer and micron sized materials thought to exhibit topological surface properties that can present a challenge, as clean surfaces are a pre-requisite for band structure measurements when using nano-ARPES or laser-ARPES in ultra-high vacuum. This issue is exacerbated when dealing with nanometer or micron sized materials, which have been prepared ex-situ and so have been exposed to atmosphere. We present the findings of an XPS study where various cleaning methods have been employed to reduce the surface contamination and preserve the surface quality for surface sensitive measurements. Microcrystals of the topological crystalline insulator SnTe were grown ex-situ and transferred into ultra high vacuum (UHV) before being treated with either atomic hydrogen, argon sputtering, annealing, or a combination of treatments. The samples were also characterised using the scanning electron microscopy, both before and after treatment. It was found that atomic hydrogen cleaning with an anneal cycle (200 °C) gave the best clean surface results.

  11. Cleaning and characterization of objects of cultural value by laser ablation

    NASA Astrophysics Data System (ADS)

    Bilmes, Gabriel M.; Freisztav, Cesar; Schinca, Daniel; Orsetti, Alberto

    2005-06-01

    Surface ablation with nanosecond laser pulses was applied to preservation, cleaning and compositional identification of objects of cultural value. On one hand, treatments of fabrics, coins, bones, and other archeological objects are shown, as well as applications to the preservation of covers, front of books and old manuscripts made in rag paper. Damage fluence thresholds for 17 different XIXth century types of papers, made by processing textiles, were determined. On the other hand, we use the spectroscopic analysis of the plasma generated as a result of laser ablation (LIBS- laser Induced Breakdown Spectroscopy-) for the determination of the elementary composition of unique pieces in anthropology and archaeology. In particular, we show applications to the identification of trace elements in Hominide teeth, of interest concerning the analysis of eating habits. We also apply LIBS to the determination of the composition of acheological objects belonging to different pre-Columbian cultures.

  12. Design Surfaces by Laser Remelting

    NASA Astrophysics Data System (ADS)

    Temmler, André; Willenborg, Edgar; Wissenbach, Konrad

    The surface of a part or product strongly influences its properties and functions. These are, e.g., abrasion and corrosion resistance, insensitivity to scratches, haptics as well as the visual impression to the customer. Therefore, many plastic parts have structured surfaces like leather textures on car dashboards. Usually these structures are integrated in the injection mould for the production of the plastic parts and then transferred to the plastic parts during the injection moulding process. A new approach to structuring metallic surfaces with laser radiation is structuring by remelting. Another approach of enhancing the appearance of design surfaces is creating a two-gloss effect by selective laser polishing. Both laser-based processes are based on reallocation of material instead of ablation.

  13. Crude Oil Remote Sensing, Characterization and Cleaning with CW and Pulsed Lasers

    NASA Technical Reports Server (NTRS)

    Kukhtareva, Tatiana; Chirita, Arc; Gallegos, Sonia C.

    2014-01-01

    For detection, identification and characterization of crude oil we combine several optical methods of remote sensing of crude oil films and emulsions (coherent fringe projection illumination (CFP), holographic in-line interferometry (HILI), and laser induced fluorescence). These methods allow the three-dimensional characterization of oil spills, important for practical applications. Combined methods of CFP and HILI are described in the frame of coherent superposition of partial interference patterns. It is shown, that in addition to detection/identification laser illumination in the green-blue region can also degrade oil slicks. Different types of surfaces contaminated by oil spills are tested: oil on the water, oil on the flat solid surfaces and oil on the curved surfaces of pipes. For the detection and monitoring of the laser-induced oil degradation in pipes, coherent fiber bundles were used. Both continuous-wave (CW) and pulsed lasers are tested using pump-probe schemes. This finding suggests that properly structured laser clean-up can be an alternative environmentally-friendly method of decontamination, as compared to the currently used chemical methods that are dangerous to environment.

  14. 40 CFR 761.369 - Pre-cleaning the surface.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Pre-cleaning the surface. 761.369 Section 761.369 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT POLYCHLORINATED BIPHENYLS (PCBs) MANUFACTURING, PROCESSING, DISTRIBUTION IN COMMERCE, AND...

  15. Low temperature self-cleaning properties of superhydrophobic surfaces

    NASA Astrophysics Data System (ADS)

    Wang, Fajun; Shen, Taohua; Li, Changquan; Li, Wen; Yan, Guilong

    2014-10-01

    Outdoor surfaces are usually dirty surfaces. Ice accretion on outdoor surfaces could lead to serious accidents. In the present work, the superhydrophobic surface based on 1H, 1H, 2H, 2H-Perfluorodecanethiol (PFDT) modified Ag/PDMS composite was prepared to investigate the anti-icing property and self-cleaning property at temperatures below freezing point. The superhydrophobic surface was deliberately polluted with activated carbon before testing. It was observed that water droplet picked up dusts on the cold superhydrophobic surface and took it away without freezing at a measuring temperature of -10 °C. While on a smooth PFDT surface and a rough surface base on Ag/PDMS composite without PFDT modification, water droplets accumulated and then froze quickly at the same temperature. However, at even lower temperature of -12 °C, the superhydrophobic surface could not prevent the surface water from icing. In addition, it was observed that the frost layer condensed from the moisture pay an important role in determining the low temperature self-cleaning properties of a superhydrophobic surface.

  16. Electrochemical 'bubble swarm' enhancement of ultrasonic surface cleaning.

    PubMed

    Birkin, P R; Offin, D G; Vian, C J B; Leighton, T G

    2015-09-01

    An investigation of surface cleaning using a swarm of gas bubbles within an acoustically activated stream is presented. Electrolysis of water at Pt microwires (100 μm diameter) to produce both hydrogen and oxygen bubbles is shown to enhance the extent of ultrasonic surface cleaning in a free flowing water stream containing an electrolyte (0.1 M Na2SO4) and low surfactant concentration (2 mM SDS). The surfactant was employed to allow control of the average size of the bubble population within the swarm. The electrochemical bubble swarm (EBS) is shown to perturb acoustic transmission through the stream. To optimise the cleaning process both the ultrasonic field and the electrochemical current are pulsed and synchronized but with different duty cycles. Cleaning action is demonstrated on structured surfaces (porcine skin and finger mimics) loaded with fluorescent particles. This action is shown to be significantly enhanced compared to that found with an inherent bubble population produced by the flow and acoustic regime alone under the same conditions. PMID:26234563

  17. Sapphire (0001) Surface, Clean and with d -Metal Overlayers

    SciTech Connect

    Verdozzi, C.; Jennison, D.R.; Schultz, P.A.; Sears, M.P.

    1999-01-01

    We present local density-functional results for structural and electronic properties of Al{sub 2}O {sub 3}(0001) , clean and with Pt and Ag adsorption. Significant surface relaxations penetrate to the third oxygen layer, 5.2 {Angstrom} below the surface. The dominant mechanism of metal adhesion is polarization and is relatively weak ({approx_equal} 0.4 and 0.6 eV/atom for Ag and Pt, respectively); however, isolated metal atoms bind up to 5{times} as strongly with an ionic bond induced by the surface Madelung potential. {copyright} {ital 1999} {ital The American Physical Society}

  18. Cleaning of biomaterial surfaces: protein removal by different solvents.

    PubMed

    Kratz, Fabian; Grass, Simone; Umanskaya, Natalia; Scheibe, Christian; Müller-Renno, Christine; Davoudi, Neda; Hannig, Matthias; Ziegler, Christiane

    2015-04-01

    The removal of biofilms or protein films from biomaterials is still a challenging task. In particular, for research investigations on real (applied) surfaces the reuse of samples is of high importance, because reuse allows the comparison of the same sample in different experiments. The aim of the present study was to evaluate the cleaning efficiency of different solvents (SDS, water, acetone, isopropanol, RIPA-buffer and Tween-20) on five different biomaterials (titanium, gold, PMMA (no acetone used), ceramic, and PTFE) with different wettability which were covered by layers of two different adsorbed proteins (BSA and lysozyme). The presence of a protein film after adsorption was confirmed by transmission electron microscopy (TEM). After treatment of the surfaces with the different solvents, the residual proteins on the surface were determined by BCA-assay (bicinchoninic acid assay). Data of the present study indicate that SDS is an effective solvent, but for several protein-substrate combinations it does not show the cleaning efficiency often mentioned in literature. RIPA-buffer and Tween-20 were more effective. They showed very low residual protein amounts after cleaning on all examined material surfaces and for both proteins, however, with small differences for the respective substrate-protein combinations. RIPA-buffer in combination with ultrasonication completely removed the protein layer as confirmed by TEM. PMID:25725311

  19. Impact of different cleaning processes on the laser damage threshold of antireflection coatings for Z-Backlighter optics at Sandia National Laboratories

    NASA Astrophysics Data System (ADS)

    Field, Ella; Bellum, John; Kletecka, Damon

    2014-12-01

    We have examined how three different cleaning processes affect the laser-induced damage threshold (LIDT) of antireflection coatings for large dimension, Z-Backlighter laser optics at Sandia National Laboratories. Laser damage thresholds were measured after the coatings were created, and again 4 months later to determine which cleaning processes were most effective. Coatings that received cleaning exhibited the highest LIDTs compared to coatings that were not cleaned. In some cases, there is nearly a twofold increase in the LIDT between the cleaned and uncleaned coatings (19.4 J/cm2 compared to 39.1 J/cm2). Higher LIDTs were realized after 4 months of aging. The most effective cleaning process involved washing the coated surface with mild detergent, and then soaking the optic in a mixture of ethyl alcohol and deionized water. Also, the laser damage results indicate that the presence of nonpropagating (NP) damage sites dominates the LIDTs of almost every optic, despite the cleaning process used. NP damage sites can be attributed to defects such as nodules in the coating or surface contamination, which suggests that pursuing further improvements to the deposition or cleaning processes are worthwhile to achieve even higher LIDTs.

  20. Influence of cleaning process on the laser-induced damage threshold of substrates

    SciTech Connect

    Shen Zhengxiang; Ding Tao; Ye Xiaowen; Wang Xiaodong; Ma Bin; Cheng Xinbin; Liu Huasong; Ji Yiqin; Wang Zhanshan

    2011-03-20

    The cleaning process of optical substrates plays an important role during the manufacture of high-power laser coatings. Two kinds of substrates, fused silica and BK7 glass, and two cleaning processes, called process 1 and process 2 having different surfactant solutions and different ultrasonic cleaning parameters, are adopted to compare the influence of the ultrasonic cleaning technique on the substrates. The evaluation standards of the cleaning results include contaminant-removal efficiency, weak absorption, and laser-induced damage threshold of the substrates. For both fused silica and BK7, process 2 is more efficient than process 1. Because acid and alkaline solutions can increase the roughness of BK7, process 2 is unsuitable for BK7 glass cleaning. The parameters of the cleaning protocol should be changed depending on the material of the optical components and the type of contamination.

  1. Laser cleaning of graffiti in Rosa Porriño granite

    NASA Astrophysics Data System (ADS)

    Fiorucci, M. P.; Lamas, J.; López, A. J.; Rivas, T.; Ramil, A.

    2011-05-01

    This paper presents preliminary results in determining the optimum parameters for graffiti removal in a ornamental granite, Rosa Porriño, by means of Nd:YVO4 laser at the wavelength of 355 nm and different fluences. The spray-paints (black, blue, red and silver) tested in this work were chemically characterized by means of elemental analysis, XRF, SEM/EDX and FTIR. The assessment of cleaning and characterization of the stone substrate before and after irradiation was performed by means of optical microscopy, SEM-EDX, and confocal microscopy. The analysis of the irradiated samples showed in some cases, damage in the granite substrate associated to thermal effects. The severity and kind of damage, depends on the laser fluence delivered, the constituent mineral irradiated, and the color used to paint the stone. So, at the highest levels of fluence the laser beam is able to scratch the surface, being the depth of the grooves in the stone measured by confocal microscopy. Moreover, SEM images show the differential damage caused in mineral constituents of granite i.e., quartz, feldspars, and biotite, the latter providing to be the most affected mineral, reaching melting even at low levels of fluence. It was appreciated that the color of the spray-paint affects the results of cleaning, and observed differences could be attributed to different organic constituents in the paints or the presence of metallic particles in its composition, as occurs with silver paint.

  2. Laser ablation of contaminants from concrete and metal surfaces. Topical report, June--December 1994

    SciTech Connect

    Freiwald, J.; Freiwald, D.A.

    1994-12-01

    Tests have demonstrated that it is possible to clean coatings off surfaces using high-power, pulsed, high-repetition-rate lasers. Purpose of this contract is to demonstrate (1) that pulsed-repetition lasers can be used to remove paint from concrete and metal surfaces, including cleaning out the surface pores, (2) that the cleaning process will result in negligible release of contaminated ablated material to the environment, and (3) that the process generates negligible additional waste compared to competing technologies. This report covers technical progress during Phase 1 of the contract and makes recommendations for technology development in Phase 2.

  3. Laser heterodyne surface profiler

    DOEpatents

    Sommargren, G.E.

    1980-06-16

    A method and apparatus are disclosed for testing the deviation of the face of an object from a flat smooth surface using a beam of coherent light of two plane-polarized components, one of a frequency constantly greater than the other by a fixed amount to produce a difference frequency with a constant phase to be used as a reference, and splitting the beam into its two components. The separate components are directed onto spaced apart points on the face of the object to be tested for smoothness while the face of the object is rotated on an axis normal to one point, thereby passing the other component over a circular track on the face of the object. The two components are recombined after reflection to produce a reflected frequency difference of a phase proportional to the difference in path length of one component reflected from one point to the other component reflected from the other point. The phase of the reflected frequency difference is compared with the reference phase to produce a signal proportional to the deviation of the height of the surface along the circular track with respect to the fixed point at the center, thereby to produce a signal that is plotted as a profile of the surface along the circular track. The phase detector includes a quarter-wave plate to convert the components of the reference beam into circularly polarized components, a half-wave plate to shift the phase of the circularly polarized components, and a polarizer to produce a signal of a shifted phase for comparison with the phase of the frequency difference of the reflected components detected through a second polarizer. Rotation of the half-wave plate can be used for phase adjustment over a full 360/sup 0/ range.

  4. Laser Surface Preparation and Bonding of Aerospace Structural Composites

    NASA Technical Reports Server (NTRS)

    Belcher, M. A.; Wohl, C. J.; Hopkins, J. W.; Connell, J. W.

    2010-01-01

    Adhesive bonds are critical to the integrity of built-up structures. Disbonds can often be detected but the strength of adhesion between surfaces in contact is not obtainable without destructive testing. Typically the number one problem in a bonded structure is surface contamination, and by extension, surface preparation. Standard surface preparation techniques, including grit blasting, manual abrasion, and peel ply, are not ideal because of variations in their application. Etching of carbon fiber reinforced plastic (CFRP) panels using a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser appears to be a highly precise and promising way to both clean a composite surface prior to bonding and provide a bond-promoting patterned surface akin to peel ply without the inherent drawbacks from the same (i.e., debris and curvature). CFRP surfaces prepared using laser patterns conducive to adhesive bonding were compared to typical prebonding surface treatments through optical microscopy, contact angle goniometry, and post-bonding mechanical testing.

  5. Laser heterodyne surface profiler

    DOEpatents

    Sommargren, Gary E.

    1982-01-01

    A method and apparatus is disclosed for testing the deviation of the face of an object from a flat smooth surface using a beam of coherent light of two plane-polarized components, one of a frequency constantly greater than the other by a fixed amount to produce a difference frequency with a constant phase to be used as a reference. The beam also is split into its two components with the separate components directed onto spaced apart points onthe face of the object to be tested for smoothness. The object is rotated on an axis coincident with one component which is directed to the face of the object at the center which constitutes a virtual fixed point. This component also is used as a reference. The other component follows a circular track on the face of the object as the object is rotated. The two components are recombined after reflection to produce a reflected frequency difference of a phase proportional to the difference in path length which is compared with the reference phase to produce a signal proportional to the deviation of the height of the surface along the circular track with respect to the fixed point at the center.

  6. Evaluation of surface sampling method performance for Bacillus Spores on clean and dirty outdoor surfaces.

    SciTech Connect

    Wilson, Mollye C.; Einfeld, Wayne; Boucher, Raymond M.; Brown, Gary Stephen; Tezak, Matthew Stephen

    2011-06-01

    Recovery of Bacillus atrophaeous spores from grime-treated and clean surfaces was measured in a controlled chamber study to assess sampling method performance. Outdoor surfaces investigated by wipe and vacuum sampling methods included stainless steel, glass, marble and concrete. Bacillus atrophaeous spores were used as a surrogate for Bacillus anthracis spores in this study designed to assess whether grime-coated surfaces significantly affected surface sampling method performance when compared to clean surfaces. A series of chamber tests were carried out in which known amounts of spores were allowed to gravitationally settle onto both clean and dirty surfaces. Reference coupons were co-located with test coupons in all chamber experiments to provide a quantitative measure of initial surface concentrations of spores on all surfaces, thereby allowing sampling recovery calculations. Results from these tests, carried out under both low and high humidity conditions, show that spore recovery from grime-coated surfaces is the same as or better than spore recovery from clean surfaces. Statistically significant differences between method performance for grime-coated and clean surfaces were observed in only about half of the chamber tests conducted.

  7. Cleaning painted surfaces: evaluation of leaching phenomenon induced by solvents applied for the removal of gel residues.

    PubMed

    Casoli, Antonella; Di Diego, Zaira; Isca, Clelia

    2014-12-01

    Cleaning is one of the most important, delicate, and at the same time controversial processes in the conservation treatment of paintings. Although a strict definition of cleaning would be the removal of dirt, grime, or other accretions (surface cleaning), in the conservation field, cleaning is used in the broader meaning to include thinning/removing altered or “unwanted layers” of materials without damaging or altering the physicochemical properties of the surfaces to be preserved. The cleaning of unvarnished paintings is one of the most critical issues that are currently discussed. Several studies exist regarding different cleaning tools, such as gels, soaps, enzymes, ionic liquids, and foams, as well as various dry methods and lasers, but only a few have been performed on the risk associated with the use of water and organic solvents for the cleaning treatments in relation to the original paint binder. The aim of the study is to verify analytically the behavior of water gelling agents during cleaning treatments and the interaction of the following elements: water or organic solvents applied for the removal of gel residues with the original lipid paint binder. For this purpose, the study was conducted on a fragment of canvas painting (sixteenth to seventeenth century) of Soprintendenza per i Beni Storici, Artistici ed Etnoantropologici del Friuli Venezia Giulia (Superintendence for the Historical, Artistic and Ethno-anthropological Heritage of Friuli Venezia Giulia), Udine by means of Fourier transform infrared spectroscopy, gas chromatography/mass spectrometry, and scanning electron microscopy. PMID:24659401

  8. Fabrication of microgrooves on a curved surface by the confocal measurement system using pulse laser and continuous laser

    NASA Astrophysics Data System (ADS)

    Noh, Jiwhan; Cho, Ilhwan; Lee, Seungwoo; Na, Suckjoo; Lee, Jae-Hoon

    2012-03-01

    In order to fabricate microgrooves on a curved surface, the curved surface was measured with a confocal system and then it was used for laser microprocessing. This paper proposes a new method of using a pulse laser for the confocal system to measure the curved surface. It also compares the conventional way of using a continuous laser and a new way of using the pulse laser with the confocal system. Using the data measured with the pulse laser for fabrication, microgrooves were fabricated on a curved surface. The width of the fabricated microgroove was 10 μm and the depth was 27 μm. The microgroove fabricated on a curved surface as a part of this study can be used in injection molding to manufacture a micropatterned plastic surface at a low cost. This plastic surface can be applied for a superhydrophobic surface, a self-cleaning surface, or a biochip.

  9. Cleaning Dirty Surfaces: A Three-Body Problem.

    PubMed

    Stoehr, Bastian; Hall, Colin; Evans, Drew; Murphy, Peter

    2016-07-20

    Human interaction with touch screens requires physical touch and hence results in contamination of these surfaces, resulting in the necessity of cleaning. In this study we discuss the three bodies of this problem and how each component contributes and can be controlled. Utilizing a standard fingerprint machine and a standard cleanability test, this study examines the influence of parameters such as the wiping speed and pressure, the material and surface area of the cloths, and the surface energy of the contaminated surfaces. It was shown that fingerprint contamination undergoes shear banding and hence is not easily removed. The degree of material removal depends on the position of the shear plane, which is influenced by surface energies and shear rates. PMID:27351355

  10. Coal surface control for advanced physical fine coal cleaning technologies

    SciTech Connect

    Morsi, B.I.; Chiang, S.H.; Sharkey, A.; Blachere, J.; Klinzing, G.; Araujo, G.; Cheng, Y.S.; Gray, R.; Streeter, R.; Bi, H.; Campbell, P.; Chiarlli, P.; Ciocco, M.; Hittle, L.; Kim, S.; Kim, Y.; Perez, L.; Venkatadri, R.

    1992-01-01

    This final report presents the research work carried out on the Coal Surface Control for Advanced Physical Fine Coal Cleaning Technologies project, sponsored by the US Department of Energy, Pittsburgh Energy Technology Center (DOE/PETC). The project was to support the engineering development of the selective agglomeration technology in order to reduce the sulfur content of US coals for controlling SO[sub 2] emissions (i.e., acid rain precursors). The overall effort was a part of the DOE/PETCs Acid Rain Control Initiative (ARCI). The overall objective of the project is to develop techniques for coal surface control prior to the advanced physical fine coal cleaning process of selective agglomeration in order to achieve 85% pyrite sulfur rejection at an energy recovery greater than 85% based on run-of-mine coal. The surface control is meant to encompass surface modification during grinding and laboratory beneficiation testing. The project includes the following tasks: Project planning; methods for analysis of samples; development of standard beneficiation test; grinding studies; modification of particle surface; and exploratory R D and support. The coal samples used in this project include three base coals, Upper Freeport - Indiana County, PA, Pittsburgh NO. 8 - Belmont County, OH, and Illinois No. 6 - Randolph County, IL, and three additional coals, Upper Freeport - Grant County- WV, Kentucky No. 9 Hopkins County, KY, and Wyodak - Campbell County, WY. A total of 149 drums of coal were received.

  11. Descaling and cleaning titanium and titanium alloy surfaces

    SciTech Connect

    Not Available

    1981-01-01

    The recommended practice covers a cleaning and descaling procedure useful to producers, users, and fabricators of titanium and titanium alloys for the removal of ordinary shop soils, oxides, and scales resulting from heat treatment operations and foreign substances present as surface contaminants. The procedures are not mandatory for removal of the indicated soils but rather serve as a guide when titanium and titanium alloys are being processed in the wrought, cast, or fabricated form. The soils should be removed prior to chemical milling, joining, plating, fabrication, and in any situation where foreign substances interfere with the corrosion resistance, stability, and quality of the finished product. The recommended practice discusses processing soil removal, blast cleaning, pickling, descaling, and inspection. (JMT)

  12. Laser cleaning of works of art: evaluation of the thermal stress induced by Er:YAG laser

    NASA Astrophysics Data System (ADS)

    De Cruz, A.; Andreotti, A.; Ceccarini, A.; Colombini, M. P.

    2014-06-01

    The Er:YAG laser has proven particularly efficient in cleaning procedures of works of art. The removal of the superficial deposits is achieved through melting, thermal decomposition and evaporation. However, the energy absorbed by vibrational modes is dissipated as heat, increasing the temperature of the surface coating that could cause damage on the object. The aim of this study was to evaluate the temperature increase induced by a Er:YAG MonaLaser (LLC., Orlando, FL, USA). To that purpose, we designed a dedicated device to perform the tests in an inert atmosphere or with a wetting agent, to measure the radiant energy per laser pulse. Tests were carried out both on graphite, which absorbs IR radiation and showed a very intense flash emission, and on different kind of samples representative of materials with different levels of conductivity and thermal diffusivity. Results obtained showed that the temperature increase in the irradiated surface depends on the substrate but never causes the damage of the organic and inorganic material. The use of a solvent as wetting agent has been also tested.

  13. Roughening and removal of surface contamination from beryllium using negative transferred-arc cleaning

    SciTech Connect

    Castro, R.G.; Hollis, K.J.; Elliott, K.E.

    1997-12-01

    Negative transferred-arc (TA) cleaning has been used extensively in the aerospace industry to clean and prepare surfaces prior to plasma spraying of thermal barrier coatings. This non-line of sight process can improve the bond strength of plasma sprayed coatings to the substrate material by cleaning and macroscopically roughening the surface. A variation of this cleaning methodology is also used in gas tungsten arc (GTA) welding to cathodically clean the surfaces of aluminum and magnesium prior to welding. Investigations are currently being performed to quantify the degree in which the negative transferred-arc process can clean and roughen metal surfaces. Preliminary information will be reported on the influence of processing conditions on roughening and the removal of carbon and other contaminates from the surface of beryllium. Optical, spectral and electrical methods to quantify cleaning of the surface will also be discussed. Applications for this technology include chemical-free precision cleaning of beryllium components.

  14. Modeling of surface cleaning by cavitation bubble dynamics and collapse.

    PubMed

    Chahine, Georges L; Kapahi, Anil; Choi, Jin-Keun; Hsiao, Chao-Tsung

    2016-03-01

    Surface cleaning using cavitation bubble dynamics is investigated numerically through modeling of bubble dynamics, dirt particle motion, and fluid material interaction. Three fluid dynamics models; a potential flow model, a viscous model, and a compressible model, are used to describe the flow field generated by the bubble all showing the strong effects bubble explosive growth and collapse have on a dirt particle and on a layer of material to remove. Bubble deformation and reentrant jet formation are seen to be responsible for generating concentrated pressures, shear, and lift forces on the dirt particle and high impulsive loads on a layer of material to remove. Bubble explosive growth is also an important mechanism for removal of dirt particles, since strong suction forces in addition to shear are generated around the explosively growing bubble and can exert strong forces lifting the particles from the surface to clean and sucking them toward the bubble. To model material failure and removal, a finite element structure code is used and enables simulation of full fluid-structure interaction and investigation of the effects of various parameters. High impulsive pressures are generated during bubble collapse due to the impact of the bubble reentrant jet on the material surface and the subsequent collapse of the resulting toroidal bubble. Pits and material removal develop on the material surface when the impulsive pressure is large enough to result in high equivalent stresses exceeding the material yield stress or its ultimate strain. Cleaning depends on parameters such as the relative size between the bubble at its maximum volume and the particle size, the bubble standoff distance from the particle and from the material wall, and the excitation pressure field driving the bubble dynamics. These effects are discussed in this contribution. PMID:25982895

  15. Surface Decontamination Using Laser Ablation Process - 12032

    SciTech Connect

    Moggia, Fabrice; Lecardonnel, Xavier; Damerval, Frederique

    2012-07-01

    A new decontamination method has been investigated and used during two demonstration stages by the Clean-Up Business Unit of AREVA. This new method is based on the use of a Laser beam to remove the contaminants present on a base metal surface. In this paper will be presented the type of Laser used during those tests but also information regarding the efficiency obtained on non-contaminated (simulated contamination) and contaminated samples (from the CEA and La Hague facilities). Regarding the contaminated samples, in the first case, the contamination was a quite thick oxide layer. In the second case, most of the contamination was trapped in dust and thin grease layer. Some information such as scanning electron microscopy (SEM), X-Ray scattering spectroscopy and decontamination factors (DF) will be provided in this paper. Laser technology appears to be an interesting one for the future of the D and D applications. As shown in this paper, the results in terms of efficiency are really promising and in many cases, higher than those obtained with conventional techniques. One of the most important advantages is that all those results have been obtained with no generation of secondary wastes such as abrasives, chemicals, or disks... Moreover, as mentioned in introduction, the Laser ablation process can be defined as a 'dry' process. This technology does not produce any liquid waste (as it can be the case with chemical process or HP water process...). Finally, the addition of a vacuum system allows to trap the contamination onto filters and thus avoiding any dissemination in the room where the process takes place. The next step is going to be a commercial use in 2012 in one of the La Hague buildings. (authors)

  16. Surface Finish after Laser Metal Deposition

    NASA Astrophysics Data System (ADS)

    Rombouts, M.; Maes, G.; Hendrix, W.; Delarbre, E.; Motmans, F.

    Laser metal deposition (LMD) is an additive manufacturing technology for the fabrication of metal parts through layerwise deposition and laser induced melting of metal powder. The poor surface finish presents a major limitation in LMD. This study focuses on the effects of surface inclination angle and strategies to improve the surface finish of LMD components. A substantial improvement in surface quality of both the side and top surfaces has been obtained by laser remelting after powder deposition.

  17. Recommended values of clean metal surface work functions

    SciTech Connect

    Derry, Gregory N. Kern, Megan E.; Worth, Eli H.

    2015-11-15

    A critical review of the experimental literature for measurements of the work functions of clean metal surfaces of single-crystals is presented. The tables presented include all results found for low-index crystal faces except cases that were known to be contaminated surfaces. These results are used to construct a recommended value of the work function for each surface examined, along with an uncertainty estimate for that value. The uncertainties are based in part on the error distribution for all measured work functions in the literature, which is included here. The metals included in this review are silver (Ag), aluminum (Al), gold (Au), copper (Cu), iron (Fe), iridium (Ir), molybdenum (Mo), niobium (Nb), nickel (Ni), palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru), tantalum (Ta), and tungsten (W)

  18. Apparatus for in situ cleaning of carbon contaminated surfaces

    DOEpatents

    Klebanoff, Leonard E.; Grunow, Philip; Graham, Jr., Samuel

    2004-08-10

    Activated gaseous species generated adjacent a carbon contaminated surface affords in-situ cleaning. A device for removing carbon contamination from a surface of the substrate includes (a) a housing defining a vacuum chamber in which the substrate is located; (b) a source of gaseous species; and (c) a source of electrons that are emitted to activate the gaseous species into activated gaseous species. The source of electrons preferably includes (i) a filament made of a material that generates thermionic electron emissions; (ii) a source of energy that is connected to the filament; and (iii) an electrode to which the emitted electrons are attracted. The device is particularly suited for photolithography systems with optic surfaces, e.g., mirrors, that are otherwise inaccessible unless the system is dismantled.

  19. Nd:YVO4 laser removal of graffiti from granite. Influence of paint and rock properties on cleaning efficacy

    NASA Astrophysics Data System (ADS)

    Rivas, T.; Pozo, S.; Fiorucci, M. P.; López, A. J.; Ramil, A.

    2012-12-01

    This paper presents the cleaning efficiency results for four differently coloured graffiti paints applied to two types of granitic stone by Nd:YVO4 laser at 355 nm. The paints were characterized in terms of mineralogy and chemistry using x-ray fluorescence, X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscope (SEM); paint absorbance in the ultraviolet-visible-infrared range (200-2000 nm) was also assessed. The studied granites had different mineralogy, texture and porosity properties. Cleaning efficiency was evaluated by polarized microscopy, SEM, FTIR spectroscopy and spectrophotometer colour measurements. The results indicate differences in the effectiveness of surface cleaning for the blue, red and black paints as opposed to the silver paint, mainly attributed to chemical composition. No evidence was found that the granite properties had a bearing on laser effectiveness, although the degree, type and spatial distribution of transgranular fissures in the stone affected the overall assessment of cleaning effectiveness. Polarized light microscopy observations and colour measurements showed that the intensity and distribution of fissures affect the depth of paint penetration, ultimately affecting the cleaning efficiency for both granites.

  20. Laser Induced Surface Chemical Epitaxy

    NASA Astrophysics Data System (ADS)

    Stinespring, Charter D.; Freedman, Andrew

    1990-02-01

    Studies of the thermal and photon-induced surface chemistry of dimethyl cadmium (DMCd) and dimethyl tellurium (DMTe) on GaAs(100) substrates under ultrahigh vacuum conditions have been performed for substrate temperatures in the range of 123 K to 473 K. Results indicate that extremely efficient conversion of admixtures of DMTe and DMCd to CdTe can be obtained using low power (5 - 10 mJ cm-2) 193 nm laser pulses at substrate temperatures of 123 K. Subsequent annealing at 473 K produces an epitaxial film.

  1. Surface magnetic enhancement for coal cleaning. Final report

    SciTech Connect

    Hwang, J.Y.

    1992-10-01

    The program consisted of a fundamental study to define the chemistry for the interactions between magnetic reagent and mineral and coal particles, a laboratory study to determine the applicability of this technology on coal cleaning, and a parameter study to evaluate the technical and economical feasibility of this technology for desulfurization and de-ashing under various processing schemes. Surface magnetic enhancement using magnetic reagent is a new technology developed at the Institute. This technology can be applied to separate pyrite and other minerals particles from coal with a magnetic separation after adsorbing magnetic reagent on the surface of pyrite and other minerals particles. Particles which have absorbed magnetic reagent are rendered magnetic. The adsorption can be controlled to yield selectivity. Thus, the separation of traditionally nonmagnetic materials with a magnetic separator can be achieved. Experiments have been performed to demonstrate the theoretical fundamentals and the applications of the technology. Adsorbability, adsorption mechanisms, and adsorption selectivity are included in the fundamental study. The effects of particle size, magnetic reagent dosage, solid contents, magnetic matrix, applied magnetic field strengths, retention times, and feed loading capacities are included in the application studies. Three coals, including Illinois No. 6, Lower Kittanning and Pocahontas seams, have been investigated. More than 90% pyritic sulfur and ash reductions have been achieved. Technical and economic feasibilities of this technology have been demonstrated in this study. Both are competitive to that of the froth flotation approach for coal cleaning.

  2. Laser Surface Hardening of AISI 1045 Steel

    NASA Astrophysics Data System (ADS)

    Li, Ruifeng; Jin, Yajuan; Li, Zhuguo; Qi, Kai

    2014-09-01

    The study investigates laser surface hardening in the AISI 1045 steel using two different types of industrial laser: a high-power diode laser (HPDL) and a CO2 laser, respectively. The effect of process parameters such as beam power, travel speed on structure, case depth, and microhardness was examined. In most cases, a heat-affected zone (HAZ) formed below the surface; a substantial increase in surface hardness was achieved. In addition, big differences were found between the hardened specimens after HPDL surface hardening and CO2 laser surface hardening. For HPDL, depths of the HAZ were almost equal in total HAZ o, without surface melting. For CO2 laser, the depths changed a lot in the HAZ, with surface melting in the center. To better understand the difference of laser hardening results when use these two types of laser, numerical (ANSYS) analysis of the heat conduction involved in the process was also studied. For HPDL method, a rectangular beam spot and uniform energy distribution across the spot were assumed, while for CO2 laser, a circular beam spot and Gaussian energy distribution were assumed. The results showed that the energy distribution variety altered the thermal cycles of the HAZ dramatically. The rectangular HPDL laser beam spot with uniform energy distribution is much more feasible for laser surface hardening.

  3. Active cleaning technique for removing contamination from optical surfaces in space

    NASA Technical Reports Server (NTRS)

    Shannon, R. L.; Gillette, R. B.; Cruz, G. A.

    1973-01-01

    An active cleaning technique for removing contaminants from optical surfaces in space was investigated with emphasis on the feasibility of using plasma exposure as a means of in-situ cleaning. The major work accomplished includes: (1) development of an in-situ reflectometer for use in conjunction with the contaminant film deposition/cleaning facility; (2) completion of Apollo Telescope Mount (ATM) filter treatment experiments to assess the effects of plasma exposure on the UV transmittance; (3) attempts to correlate the atomic oxygen flux with cleaning rate; (4) completion of in-situ butadien contamination/plasma cleaning/UV reflectance measurement experiments; (5) carbon cleaning experiments using various gases; (6) completion of silicone contamination/cleaning experiments; and (7) experiments conducted at low chamber pressures to determine cleaning rate distribution and contamination of surfaces adjacent to those being cleaned.

  4. Solid Lubrication Fundamentals and Applications. Properties of Clean Surfaces: Adhesion, Friction, and Wear

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1998-01-01

    This chapter presents the adhesion, friction, and wear behaviors of smooth, atomically clean surfaces of solid-solid couples, such as metal-ceramic couples, in a clean environment. Surface and bulk properties, which determine the adhesion, friction, and wear behaviors of solid-solid couples, are described. The primary emphasis is on the nature and character of the metal, especially its surface energy and ductility. Also, the mechanisms of friction and wear for clean, smooth surfaces are stated.

  5. Cleaning Efficiencies of Three Cleaning Agents on Four Different Surfaces after Contamination by Gemcitabine and 5-fluorouracile.

    PubMed

    Böhlandt, Antje; Groeneveld, Svenja; Fischer, Elke; Schierl, Rudolf

    2015-01-01

    Occupational exposure to antineoplastic drugs has been documented for decades showing widespread contamination in preparation and administration areas. Apart from preventive measures, efficient cleaning of surfaces is indispensable to minimize the exposure risk. The aim of this study was to evaluate the efficiency of three cleaning agents after intentional contamination by gemcitabine (GEM) and 5-fluorouracile (5-FU) on four different surface types usually installed in healthcare settings. Glass, stainless steel, polyvinylchloride (PVC), and laminated wood plates were contaminated with 20 ng/μl GEM and 2 ng/μl 5-FU solutions. Wipe samples were analyzed for drug residues after cleaning with a) distilled water, b) aqueous solution containing sodium dodecyl sulfate (10 mM) and 2-propanol (SDS-2P), and c) Incides N (pre-soaked) alcoholic wipes. Quantification was performed by high-performance liquid chromatography (HPLC) for GEM and gas chromato-graphy-tandem mass spectrometry (GCMS/MS) for 5-FU. Recovery was determined and cleaning efficiency was calculated for each scenario. Mean recoveries were 77-89% for GEM and 24-77% for 5-FU and calculated cleaning efficiencies ranged between 95 and 100% and 89 and 100%, respectively. Residual drug amounts were detected in the range nd (not detected) - 84 ng GEM/sample and nd - 6.6 ng 5-FU/sample depending on surface type and cleaning agent. Distilled water and SDS-2P had better decontamination outcomes than Incides N wipes on nearly all surface types, especially for GEM. Regarding 5-FU, the overall cleaning efficiency was lower with highest residues on laminated wood surfaces. The tested cleaning procedures are shown to clean glass, stainless steel, PVC, and laminated wood with an efficiency of 89-100% after contamination with GEM and 5-FU. Nevertheless, drug residues could be verified by wipe samples. Pure distilled water and SDS in an alcoholic-aqueous solution expressed an efficient cleaning performance, especially with

  6. EWOD driven cleaning of bioparticles on hydrophobic and superhydrophobic surfaces.

    PubMed

    Jönsson-Niedziółka, M; Lapierre, F; Coffinier, Y; Parry, S J; Zoueshtiagh, F; Foat, T; Thomy, V; Boukherroub, R

    2011-02-01

    Environmental air monitoring is of great interest due to the large number of people concerned and exposed to different possible risks. From the most common particles in our environment (e.g. by-products of combustion or pollens) to more specific and dangerous agents (e.g. pathogenic micro-organisms), there are a large range of particles that need to be controlled. In this article we propose an original study on the collection of electrostatically deposited particles using electrowetting droplet displacement. A variety of particles were studied, from synthetic particles (e.g. Polystyrene Latex (PSL) microsphere) to different classes of biological particle (proteins, bacterial spores and a viral simulant). Furthermore, we have compared ElectroWetting-On-Dielectric (EWOD) collecting efficiency using either a hydrophobic or a superhydrophobic counter electrode. We observe different cleaning efficiencies, depending on the hydrophobicity of the substrate (varying from 45% to 99%). Superhydrophobic surfaces show the best cleaning efficiency with water droplets for all investigated particles (MS2 bacteriophage, BG (Bacillus atrophaeus) spores, OA (ovalbumin) proteins, and PSL). PMID:21103534

  7. Remote plasma cleaning of optical surfaces: Cleaning rates of different carbon allotropes as a function of RF powers and distances

    NASA Astrophysics Data System (ADS)

    Cuxart, M. González; Reyes-Herrera, J.; Šics, I.; Goñi, A. R.; Fernandez, H. Moreno; Carlino, V.; Pellegrin, E.

    2016-01-01

    An extended study on an advanced method for the cleaning of carbon contaminations from large optical surfaces using a remote inductively coupled low-pressure RF plasma source (GV10x DownStream Asher) is reported. Technical and scientific features of this scaled up cleaning process are analysed, such as the cleaning efficiency for different carbon allotropes (amorphous and diamond-like carbon) as a function of feedstock gas, RF power (from 30 to 300 W), and source-object distances (415 to 840 mm). The underlying physical phenomena for these functional dependences are discussed.

  8. Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces

    SciTech Connect

    Robert F. Hicks; Hans W. Herrmann

    2003-12-15

    The purpose of this project was to demonstrate a practical, environmentally benigh technology for the surface decontamination and decommissioning of radioactive waste. A low temperature, atmospheric pressure plasma has been developed with initial support from the DOE, Environmental Management Sciences Program. This devise selectively etches radioactive metals from surfaces, rendering objects radiation free and suitable for decommissioning. The volatile reaction products are captured on filters, which yields a tremendous reduction in the volume of the waste. The technology shows a great potential for accelerating the clean-up effort for the equipment and structures contaminated with radioactive materials within the DOE complex. The viability of this technology has been demonstrated by selectively and rapidly stripping uranium from stainless steel surfaces at low temperature. Studies on uranium oxide have shown that etch rates of 4.0 microns per minute can be achieved at temperature below 473 K. Over the past three years, we have made numerous improvements in the design of the atmospheric pressure plasma source. We are now able to scale up the plasma source to treat large surface areas.

  9. Method for in-situ cleaning of carbon contaminated surfaces

    DOEpatents

    Klebanoff, Leonard E.; Grunow, Philip; Graham, Jr., Samuel

    2006-12-12

    Activated gaseous species generated adjacent a carbon contaminated surface affords in-situ cleaning. A device for removing carbon contamination from a surface of the substrate includes (a) a housing defining a vacuum chamber in which the substrate is located; (b) a source of gaseous species; and (c) a source of electrons that are emitted to activate the gaseous species into activated gaseous species. The source of electrons preferably includes (i) a filament made of a material that generates thermionic electron emissions; (ii) a source of energy that is connected to the filament; and (iii) an electrode to which the emitted electrons are attracted. The device is particularly suited for photolithography systems with optic surfaces, e.g., mirrors, that are otherwise inaccessible unless the system is dismantled. A method of removing carbon contaminants from a substrate surface that is housed within a vacuum chamber is also disclosed. The method employs activated gaseous species that react with the carbon contaminants to form carbon containing gaseous byproducts.

  10. Surface Structure and Surface Electronic States Related to Plasma Cleaning of Silicon and Germanium

    NASA Astrophysics Data System (ADS)

    Cho, Jaewon

    This thesis discusses the surface structure and the surface electronic states of Si and Ge(100) surfaces as well as the effects of oxidation process on the silicon oxide/Si(100) interface structure. The H-plasma exposure was performed in situ at low temperatures. The active species, produced in the H-plasma by the rf-excitation of H_2 gas, not only remove microcontaminants such as oxygen and carbon from the surface, but also passivate the surface with atomic hydrogen by satisfying the dangling bonds of the surface atoms. The surfaces were characterized by Angle Resolved UV-Photoemission Spectroscopy (ARUPS) and Low Energy Electron Diffraction (LEED). In the case of Si(100), H-plasma exposure produced ordered H-terminated crystallographic structures with either a 2 x 1 or 1 x 1 LEED pattern. The hydride phases, found on the surfaces of the cleaned Si(100), were shown to depend on the temperature of the surface during H-plasma cleaning. The electronic states for the monohydride and dihydride phases were identified by ARUPS. When the plasma cleaned surface was annealed, the phase transition from the dihydride to monohydride was observed. The monohydride Si-H surface bond was stable up to 460^circC, and the dangling bond surface states were identified after annealing at 500^circC which was accompanied by the spectral shift. The H-terminated surface were characterized to have a flat band structure. For the Ge(100) surface, an ordered 2 x 1 monohydride phase was obtained from the surface cleaned at 180 ^circC. After plasma exposure at <=170^circC a 1 x 1 surface was observed, but the ARUPS indicated that the surface was predominantly composed of disordered monohydride structures. After annealing above the H-dissociation temperatures, the shift in the spectrum was shown to occur with the dangling bond surface states. The H-terminated surfaces were identified to be unpinned. The interface structure of silicon oxide/Si(100) was studied using ARUPS. Spectral shifts were

  11. Cleaning of optical surfaces by capacitively coupled RF discharge plasma

    SciTech Connect

    Yadav, P. K. Rai, S. K.; Nayak, M.; Lodha, G. S.; Kumar, M.; Chakera, J. A.; Naik, P. A.; Mukherjee, C.

    2014-04-24

    In this paper, we report cleaning of carbon capped molybdenum (Mo) thin film by in-house developed radio frequency (RF) plasma reactor, at different powers and exposure time. Carbon capped Mo films were exposed to oxygen plasma for different durations at three different power settings, at a constant pressure. After each exposure, the thickness of the carbon layer and the roughness of the film were determined by hard x-ray reflectivity measurements. It was observed that most of the carbon film got removed in first 15 minutes exposure. A high density layer formed on top of the Mo film was also observed and it was noted that this layer cannot be removed by successive exposures at different powers. A significant improvement in interface roughness with a slight improvement in top film roughness was observed. The surface roughness of the exposed and unexposed samples was also confirmed by atomic force microscopy measurements.

  12. LEEM investigations of clean surfaces driven by energetic ion beams

    SciTech Connect

    Abbamonte, Peter M.

    2013-04-24

    The original purpose of this award was to use low‐energy electron microscopy (LEEM) to explore the dynamics of surfaces of clean single crystal surfaces when driven by a beam of energetic ions. The goal was to understand the nanoscience of hyperthermal growth, surface erosion by sublimation and irradiation, operation of surface sinks in irradiated materials, diffusion on driven surfaces, and the creation of structural patterns. This project was based on a novel LEEM system constructed by C. P. Flynn, which provided real‐time imaging of surface dynamics by scattering low energy electrons. With the passing of Prof. Flynn in late 2011, this project was completed under a slightly different scope by constructing a low‐energy, inelastic electron scattering (EELS) instrument. Consistent with Flynn's original objectives for his LEEM system, this device probes the dynamics of crystal surfaces. However the measurements are not carried out in real time, but instead are done in the frequency domain, through the energy lost from the probe electrons. The purpose of this device is to study the collective bosonic excitations in a variety of materials, including high temperature superconductors, topological insulators, carbon allotropes including (but not limited to) graphene, etc. The ultimate goal here is to identify the bosons that mediate interactions in these and other materials, with hopes of shedding light on the origin of many exotic phenomena including high temperature superconductivity. We completed the construction of a low‐energy EELS system that operates with an electron kinetic energy of 7 - 10 eV. With this instrument now running, we hope to identify, among other things, the bosons that mediate pairing in high temperature superconductors. Using this instrument, we have already made our first discovery. Studying freshly cleaved single crystals of Bi{sub 2}Se{sub 3}, which is a topological insulator, we have observed a surface excitation at an energy loss of

  13. SAGE SOLVENT ALTERNATIVES GUIDE: SYSTEM IMPROVEMENTS FOR SELECTING INDUSTRIAL SURFACE CLEANING ALTERNATIVES

    EPA Science Inventory

    The paper describes computer software, called SAGE, that can provide not only cleaning recommendations but also general information on various surface cleaning options. In short, it is an advisory system which can provide users with vital information on the cleaning process optio...

  14. Laser surface texturing of tool steel: textured surfaces quality evaluation

    NASA Astrophysics Data System (ADS)

    Šugár, Peter; Šugárová, Jana; Frnčík, Martin

    2016-05-01

    In this experimental investigation the laser surface texturing of tool steel of type 90MnCrV8 has been conducted. The 5-axis highly dynamic laser precision machining centre Lasertec 80 Shape equipped with the nano-second pulsed ytterbium fibre laser and CNC system Siemens 840 D was used. The planar and spherical surfaces first prepared by turning have been textured. The regular array of spherical and ellipsoidal dimples with a different dimensions and different surface density has been created. Laser surface texturing has been realized under different combinations of process parameters: pulse frequency, pulse energy and laser beam scanning speed. The morphological characterization of ablated surfaces has been performed using scanning electron microscopy (SEM) technique. The results show limited possibility of ns pulse fibre laser application to generate different surface structures for tribological modification of metallic materials. These structures were obtained by varying the processing conditions between surface ablation, to surface remelting. In all cases the areas of molten material and re-cast layers were observed on the bottom and walls of the dimples. Beside the influence of laser beam parameters on the machined surface quality during laser machining of regular hemispherical and elipsoidal dimple texture on parabolic and hemispherical surfaces has been studied.

  15. Surface emitting lasers with combined output

    NASA Technical Reports Server (NTRS)

    Carlin, Donald B. (Inventor)

    1990-01-01

    Surface emitting lasers are laterally aligned and coupled together and also have their light output signals combined. This results in greater phase and frequency coherency and narrower and reduced amplitude sidelobes. Preferably, not more than two lasers are longitudinally aligned along the same axis for still greater coherency compared with adding the light output signals of more than two longitudinally aligned lasers. The lasers can be of the DH-LOC type or of the QW type.

  16. Laser Surface Preparation for Adhesive Bonding of Ti-6Al-4V

    NASA Technical Reports Server (NTRS)

    Belcher, Marcus A.; List, Martina S.; Wohl, Christopher J.; Ghose, Sayata; Watson, Kent A.; Hopkins, John W.; Connell, John W.

    2010-01-01

    Adhesively bonded structures are potentially lighter in weight than mechanically fastened ones, but existing surface treatments are often considered unreliable. Two main problems in achieving reproducible and durable adhesive bonds are surface contamination and variability in standard surface preparation techniques. In this work three surface pretreatments were compared: laser etching with and without grit blasting and conventional Pasa-Jell treatment. Ti-6Al-4V surfaces were characterized by contact angle goniometry, optical microscopy, and X-ray photoelectron spectroscopy (XPS). Laser -etching was found to produce clean surfaces with precisely controlled surface topographies and PETI-5 lap shear strengths and durabilities were equivalent to those produced with Pasa-Jell.

  17. Laser treatment of white China surface

    NASA Astrophysics Data System (ADS)

    Osvay, K.; Képíró, I.; Berkesi, O.

    2006-04-01

    The surface of gloss fired porcelain with and without raw glaze coating was radiated by a CO 2 laser working at 10.6 μm, a choice resulted from spectroscopic studies of suspensions made of China. The shine of the untreated sample was defined as the distribution of micro-droplets on the surface. The surface alterations due to laser heating were classified by the diameter of the completely melted surface, the ring of the surface at the threshold of melting, and the size of microscopic cracks. The diameter of the laser treated area was in the range of 3 mm, while the incident laser power and the duration of laser heating were varied between 1 and 10 W and 1-8 min, respectively. The different stages of surface modifications were attributed primarily to the irradiating laser power and proved to be rather insensitive to the duration of the treatment. We have found a range of parameters under which the white China surface coated with raw glaze and followed by laser induced melting exhibited very similar characteristics to the untreated porcelain. This technique seems prosperous for laser assisted reparation of small surface defects of unique China samples after the firing process.

  18. Cleaning of optical components for high-power laser-based firing systems

    SciTech Connect

    Sparrow, B.D.; Hendrix, J.L.

    1993-08-01

    This report discusses the progress of AlliedSignal Inc., Kansas City Division (KCD), in addressing the issues of cleaning of hardware and optical components for laser-based firing sets. These issues are acceptability of cleaning processes and techniques of other government programs to the quality, reliability, performance, stockpile life, materials compatibility issues, and, perhaps most important, environmentally conscious manufacturing requirements of the Department of Energy (DOE). A review of ``previous cleaning art`` is presented using Military Standards (MIL STDs) and Military Interim Specifications (MISs) as well as empirical data compiled by the authors. Observations on processes and techniques used in building prototype hardware and plans for future work are presented.

  19. Laser decontamination of epoxy painted concrete surfaces in nuclear plants

    NASA Astrophysics Data System (ADS)

    Anthofer, A.; Lippmann, W.; Hurtado, A.

    2014-04-01

    Laser technology offers an efficient decontamination of surfaces contaminated by polychlorinated biphenyls (PCB) by precise application of highly focused laser beam power. In the context of nuclear decommissioning all walls and floors of a reactor building have to be cleaned from chemical-toxic substances. State of the art is a manual and mechanic ablation and a subsequent treatment in a hazardous waste incinerator. In this study, alternatively, a laser-based system exhibiting, decontamination rates of up to 6.4 m2/h has been operated using a 10 kW diode laser in continuous wave (CW) mode with a spot size of 45×10 mm2 and a wavelength of 980-1030 nm. The system allows a rapid heating of the surfaces up to temperatures of more than 1000 °C leading to ablation and thermal decomposition of PCB in one process step. Thermal quenching prevents formation of polychlorinated dioxines (PCDD) and polychlorinate furans (PCDF) in the flue gas. Additionally, an in situ measurement system based on laser induced fluorescence (LIF) is developed to monitor the thermal decomposition of PCB. For initial experiments samples covered with epoxy paint were used to evaluate the process and to carry out finite element based simulations. In this paper, experimental results of ablation tests by laser irradiation of epoxy painted concrete are presented and discussed.

  20. Development of construction specifications to attain clean rooms for the NOVA laser facility

    SciTech Connect

    Benedix, C.P.

    1980-02-01

    This paper describes the process of defining technical requirements for a major Department of Energy Research and Development Facility and subsequent development of construction specifications for the clean spaces in that facility. The organizational interactions between technical client, Engineering and Construction elements are described. The importance of an interdisciplinary team approach is stressed. A brief description of the SHIVA Laser and NOVA Laser Clean Spaces is included to indicate the scope of the facility undertaking. A number of potential pitfalls are discussed that may be helpful to designers of new facilities.

  1. Temporal pulse cleaning by a self-diffraction process for ultrashort laser pulses

    NASA Astrophysics Data System (ADS)

    Xie, Na; Zhou, Kainan; Sun, Li; Wang, Xiaodong; Guo, Yi; Li, Qing; Su, Jingqin

    2014-11-01

    Applying the self-diffraction process to clean ultrashort laser pulses temporally is a recently developed effective way to temporal contrast enhancement. In this paper, we attempt to clean ultrashort laser pulses temporally by the self-diffraction process. Experiments were carried out to study the temporal contrast improvement in the front-end system of an ultraintense and ultrashort laser facility, i.e. the super intense laser for experiment on the extremes (SILEX-I). The results show that the maximum conversion efficiency of the first-order self-diffraction (SD1) pulse is 11%. The temporal contrast of the SD1 signal is improved by two orders of magnitude, i.e. to 103, for a 2.4-ns prepulse with initial contrast of ~10. For a 5.5 -ns prepulse with initial contrast of 2×103, the temporal contrast of the SD1 signal is improved by more than three orders of magnitude.

  2. Self-cleaning of superhydrophobic surfaces by spontaneously jumping condensate drops

    NASA Astrophysics Data System (ADS)

    Wisdom, Katrina; Watson, Jolanta; Watson, Gregory; Chen, Chuan-Hua

    2012-11-01

    The self-cleaning function of superhydrophobic surfaces is conventionally attributed to the removal of contaminating particles by impacting or rolling water droplets, which implies the action of external forces such as gravity. Here, we demonstrate a new self-cleaning mechanism, whereby condensate drops spontaneously jump upon coalescence on a superhydrophobic surface, and the merged drop self-propels away from the surface along with the contaminants. The jumping-condensate mechanism is shown to autonomously clean superhydrophobic cicada wings, where the contaminating particles cannot be removed by external wind flow. Our findings offer new insights for the development of self-cleaning materials.

  3. Photoinduced laser etching of a diamond surface

    SciTech Connect

    Kononenko, V V; Komlenok, M S; Pimenov, S M; Konov, V I

    2007-11-30

    Nongraphitising ablation of the surface of a natural diamond single crystal irradiated by nanosecond UV laser pulses is studied experimentally. For laser fluences below the diamond graphitisation threshold, extremely low diamond etching rates (less than 1nm/1000 pulses) are obtained and the term nanoablation is used just for this process. The dependence of the nanoablation rate on the laser fluence is studied for samples irradiated both in air and in oxygen-free atmosphere. The effect of external heating on the nanoablation rate is analysed and a photochemical mechanism is proposed for describing it. (interaction of laser radiation with matter. laser plasma)

  4. Ultraviolet laser treatment of titanium surface

    NASA Astrophysics Data System (ADS)

    Balchev, Ivaylo; Minkovski, Nikolai; Dimitrov, Krasimir; Shipochka, Maria; Barbucha, Robert

    2016-02-01

    Interaction of a third harmonic of DPSS laser, wavelength 355 nm and pulse duration of 30 ns with titanium wafers was studied. It was investigated the structure of laser ablated titanium surface, depending on the laser beam scanning speed, and laser pulse frequency. The titanium surface modification was studied by scanning electron microscopy (SEM) and XPS (X- ray Photoelectron Spectroscopy). Nanosecond irradiation with ultraviolet light of Ti plate led to the formation of high porous granular structures consisting of agglomerated micro- and submicro- particles.

  5. Vertical Cavity Surface Emitting Lasers for communications

    NASA Astrophysics Data System (ADS)

    Rorison, J. M.

    2000-12-01

    Vertical Cavity Surface Emitting Lasers (VCSELs) are a novel type of laser in which the lasing light is emitted from the surface of the device, perpendicular to the gain layer, rather than from the edge of the laser, parallel to the gain layer. These lasers show interesting behavior, particularly involving mode dynamics and polarization. They show promising characteristics for use in communications applications but their behavior needs to be further understood before they can reach their potential. This chapter attempts to review VCSELs generally and discuss their use in communications systems.

  6. Laser-assisted photoemission from surfaces

    SciTech Connect

    Saathoff, G.; Miaja-Avila, L.; Murnane, M. M.; Kapteyn, H. C.; Aeschlimann, M.

    2008-02-15

    We investigate the laser-assisted photoelectric effect from a solid surface. By illuminating a Pt(111) sample simultaneously with ultrashort 1.6 and 42 eV pulses, we observe sidebands in the extreme ultraviolet photoemission spectrum, and accurately extract their amplitudes over a wide range of laser intensities. Our results agree with a simple model, in which soft x-ray photoemission is accompanied by the interaction of the photoemitted electron with the laser field. This strong effect can definitively be distinguished from other laser surface interaction phenomena, such as hot electron excitation, above-threshold photoemission, and space-charge acceleration. Thus, laser-assisted photoemission from surfaces promises to extend pulse duration measurements to higher photon energies, as well as opening up measurements of femtosecond-to-attosecond electron dynamics in solid and surface-adsorbate systems.

  7. Efficiency of surface cleaning by a glow discharge for plasma spraying coating

    NASA Astrophysics Data System (ADS)

    Kadyrmetov, A. M.; Kashapov, N. F.; Sharifullin, S. N.; Saifutdinov, A. I.; Fadeev, S. A.

    2016-06-01

    The article presents the results of experimental studies of the quality of cleaning steel surfaces by a glow discharge for plasma spraying. Shows the results of measurements of the angle of surface wetting and bond strength of the plasma coating to the surface treated. The dependence of the influence of the glow discharge power, chamber pressure, distance between the electrodes and the processing time of the surface on cleaning efficiency. Optimal fields of factors is found. It is shown increase joint strength coating and base by 30-80% as a result of cleaning the substrate surface by a glow discharge plasma spraying.

  8. Marker and pen graffiti cleaning on diverse calcareous stones by different laser techniques

    NASA Astrophysics Data System (ADS)

    Andriani, S. E.; Catalano, I. M.; Daurelio, G.; Albanese, A.

    2007-05-01

    Industries nowadays continuously produce new types of inks for markers and pens, so new different graffiti appear . In this paper laser cleaning tests on 41 new marker and pen types ( fluorescent, permanent, water-based, acrylic tempera, metallic paint, waterproof inks ), applied into laboratory on different litho- type samples (Chianca, Travertino di Roma, Tufo Carparo fine grain, Sabbie), typical stones employed in much more monuments in Puglia and Italian architectures were carried out. The same ones, were exposed for twelve months to outdoor ageing, subject to sunshine, rain, wind, IR and UV solar radiations. Ablation experiments and tests by using different cleaning techniques, each one in Dry and Wet condition (classic technique, Daurelio technique 1 and Daurelio technique 2 and others new techniques) and two different Nd:YAG laser systems (Palladio by QUANTA SYSTEM and SMART CLEAN II by EL.EN.), were adopted. The experimental modes, N-Mode (1064nm - 150, 300 and 500 μs pulse duration), Q-Switch (1064nm - 8 ns pulse duration) and SFR (Short Free Running - 1064 nm - 40 to 110μs pulse duration) were tested on each marked stones. It was found that according to the different ink types and stone substrate, Q-Switch laser cleaning ablation with optimized laser technique are the best solution to marker an pen graffiti removal. The work is still in progress.

  9. Morphometric analysis of root canal cleaning after rotary instrumentation with or without laser irradiation

    NASA Astrophysics Data System (ADS)

    Marchesan, Melissa A.; Geurisoli, Danilo M. Z.; Brugnera, Aldo, Jr.; Barbin, Eduardo L.; Pecora, Jesus D.

    2002-06-01

    The present study examined root canal cleaning, using the optic microscope, after rotary instrumentation with ProFile.04 with or without laser application with different output energies. Cleaning and shaping can be accomplished manually, with ultra-sonic and sub-sonic devices, with rotary instruments and recently, increasing development in laser radiation has shown promising results for disinfection and smear layer removal. In this study, 30 palatal maxillary molar roots were examined using an optic microscope after rotary instrumentation with ProFile .04 with or without Er:YAG laser application (KaVo KeyLaser II, Germany) with different output energies (2940 nm, 15 Hz, 300 pulses, 500 milli-sec duration, 42 J, 140 mJ showed on the display- input, 61 mJ at fiberoptic tip-output and 140 mJ showed on the display-input and 51 mJ at fiberoptic tip-output). Statistical analysis showed no statistical differences between the tested treatments (ANOVA, p>0.05). ANOVA also showed a statistically significant difference (p<0.01) between the root canal thirds, indicating that the middle third had less debris than the apical third. We conclude that: 1) none of the tested treatments led to totally cleaned root canals; 2) all treatments removed debris similarly, 3) the middle third had less debris than the apical third; 4) variation in output energy did not increase cleaning.

  10. Cleaning and passivation of copper surfaces to remove surface radioactivity and prevent oxide formation

    SciTech Connect

    Hoppe, Eric W.; Seifert, Allen; Aalseth, Craig E.; Bachelor, Paula P.; Day, Anthony R.; Edwards, Danny J.; Hossbach, Todd W.; Litke, Kevin E.; McIntyre, Justin I.; Miley, Harry S.; Schulte, Shannon M.; Smart, John E.; Warren, Glen A.

    2007-08-21

    High-purity copper is an attractive material for constructing ultra-low-background radiation measurement devices. Many low-background experiments using high-purity copper have indicated surface contamination emerges as the dominant background. Radon daughters plate out on exposed surfaces, leaving a residual 210Pb background that is difficult to avoid. Dust is also a problem; even under cleanroom conditions, the amount of U and Th deposited on surfaces can represent the largest remaining background. To control these backgrounds, a copper cleaning chemistry has been developed. Designed to replace an effective, but overly aggressive concentrated nitric acid etch, this peroxide-based solution allows for a more controlled cleaning of surfaces. The acidified hydrogen peroxide solution will generally target the Cu+/Cu2+ species which are the predominant surface participants, leaving the bulk of copper metal intact. This preserves the critical tolerances of parts and eliminates significant waste disposal issues. Accompanying passivation chemistry has also been developed that protects copper surfaces from oxidation. Using a high-activity polonium surface spike, the most difficult-to-remove daughter isotope of radon, the performance of these methods are quantified. © 2001 Elsevier Science. All rights reserved

  11. Processing of polymer surfaces by laser radiation

    NASA Astrophysics Data System (ADS)

    Kreutz, E. W.; Frerichs, H.; Stricker, J.; Wesner, D. A.

    1995-11-01

    The processing of polymer surfaces by laser radiation is investigated as a function of laser parameters (fluence, mode of operation) and processing variables (repetition rate, pulse number). Polymers under investigation are polyamide, polymethylmethacrylate, polypropylene, polystyrene, polycarbonate, acrylonitrile-butadiene-styrene copolymer, styrene-acrylonitrile copolymer, polybutadiene terephtalate, and polyoxymethylene, which are studied in air within different processing regimes such as modification of surface properties for subsequent metallization and removal of material for structuring of surface geometry. The metallization of polymers, which are pretreated by laser irradiation, wet chemical etching or plasma etching, is performed via electroplating and physical vapour deposition as a function of surface properties. The removal of polymers including non-thermal and thermal processes is done by direct processing techniques in the demagnification mode within one processing step. The diagnosis and the modelling of physical processes involved in tailoring the surface properties of polymers with laser radiation have to be implied to improve any application of these materials.

  12. Laser Surface Preparation for Adhesive Bonding of Aerospace Structural Composites

    NASA Technical Reports Server (NTRS)

    Belcher, M. A.; Wohl, C. J.; Hopkins, J. W.; Connell, J. W.

    2010-01-01

    Adhesive bonds are critical to the integrity of built-up structures. Disbonds can often be detected but the strength of adhesion between surfaces in contact is not obtainable without destructive testing. Typically the number one problem in a bonded structure is surface contamination, and by extension, surface preparation. Standard surface preparation techniques, including grit blasting, manual abrasion, and peel ply, are not ideal because of variations in their application. Etching of carbon fiber reinforced plastic (CFRP) panels using a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser appears to be a highly precise and promising way to both clean a composite surface prior to bonding and provide a bond-promoting patterned surface akin to peel ply without the inherent drawbacks from the same (i.e., debris and curvature). CFRP surfaces prepared using laser patterns conducive to adhesive bonding were compared to typical pre-bonding surface treatments through optical microscopy, contact angle goniometry, and post-bonding mechanical testing.

  13. In-depth assessment of modifications induced during the laser cleaning of modern paintings

    NASA Astrophysics Data System (ADS)

    Selimis, Alexandros; Vounisiou, Panagiota; Tserevelakis, George J.; Melessanaki, Kristalia; Pouli, Paraskevi; Filippidis, George; Beltsios, Costas; Georgiou, Savas; Fotakis, Costas

    2009-07-01

    A critical challenge for the broader implementation of laser cleaning interventions in modern paintings is the assessment of the extent of any photochemical or structural modifications induced in the original substrate following laser irradiation. For this reason, we investigate several polymeric materials (PMMA, Paraloid B72) doped with aromatic photosensitisers (PhenI, POPOP) of known photochemistry, coated with uniform layers of acrylics of different thicknesses to simulate real case scenarios. Following laser irradiation, a variety of spectroscopic techniques LIF, MPEF are employed for the in depth monitoring of any photochemical and structural modifications induced in the bulk material.

  14. Laser ablation cleaning of an underwater archaeological bronze spectacle plate from the H.M.S. DeBraak shipwreck

    NASA Astrophysics Data System (ADS)

    Dajnowski, Bartosz A.

    2013-05-01

    Laser ablation was successfully used to sequentially remove layers of concretion and corrosion from the surface of a copper alloy spectacle plate from the shipwreck of His Majesty's Sloop of War DeBraak. The H.M.S. DeBraak was a single-masted cutter that was originally a Dutch ship until it was taken by the British, refitted, and repurposed as a Royal Navy ship in 1796. The ship sank along the Delaware coast in 1798 and artifacts were recovered from the wreck site in 1984. This spectacle plate is an important part of the ships rudder and it is part of the collection of the Delaware Division of Historical and Cultural Affairs. The object was brought the Winterthur/University of Delaware Program in Art Conservation for treatment. The object was examined with cross section microscopy, Raman spectroscopy, X-ray fluorescence spectroscopy (XRF), and Energy Dispersive Spectroscopy (EDS) as well as Back Scattered Electron (BSE) analysis with a Scanning Electron Microscopy (SEM). Interestingly, layers of both copper and iron corrosion products were identified within the concretion. A 1064nm Long Q-Switch (LQS) laser with 100ns pulses was tested along with a Short Free Running (SFR) with 60 - 130 microseconds pulses, at various fluences and frequencies, to determine optimal cleaning parameters for removing the concretion. Laser cleaning also revealed fragments of wood from the original rudder, which were previously trapped within the concretion. After laser cleaning, the spectacle plate was treated with 3% Benzotriazole in ethanol and then given a protective microcrystalline wax coating.

  15. IBA analysis of a laser cleaned archaeological metal object: The San Esteban de Gormaz cross (Soria-Spain)

    NASA Astrophysics Data System (ADS)

    Zucchiatti, A.; Gutiérrez Neira, P. C.; Climent-Font, A.; Escudero, C.; Barrera, M.

    2011-12-01

    The object under study, a 12th century gilded copper cross with a wooden core, now almost disappeared, shows the typical features produced by a long burial time: the entire surface of the copper alloys is covered by several layers of degradation products, which hinder the "legibility" of the cross in terms of the original materials and manufacturing techniques employed. In its cleaning several techniques have been applied and compared (dry and wet laser ablation, mechanical ablation, ultrasound brush). In the intermediate cleaning phase the cross has been extensively analysed with the external proton micro-beam of the Centro de Micro-Análisis de Materiales (CMAM) of the Universidad Autónoma de Madrid. PIXE and RBS techniques have been used in parallel, to asses both the chemical composition and the layered structure of cleaned and original parts with the aim of verifying that none of the object structural features are being modified by the cleaning process leaving intact the possibility of artistic interpretation of the object (e.g. small series production of the cross elements). The recovery of this exceptional ornamental object is made possible by the coordinated work of several professionals coming from various disciplines and aimed at establishing the importance of this cross in terms of its physical appearance and in terms of the manufacturing techniques.

  16. Innovative Laser Ablation Technology for Surface Decontamination

    SciTech Connect

    Chen, Winston C. H.

    2003-06-01

    The objective of this project is to develop a novel laser ablation in liquid for surface decontamination. It aims to achieve more efficient surface decontamination without secondary contamination. Another aim is to make this surface decontamination technology becomes economically feasible for large scale decontamination.

  17. Metal surface nitriding by laser induced plasma

    NASA Astrophysics Data System (ADS)

    Thomann, A. L.; Boulmer-Leborgne, C.; Andreazza-Vignolle, C.; Andreazza, P.; Hermann, J.; Blondiaux, G.

    1996-10-01

    We study a nitriding technique of metals by means of laser induced plasma. The synthesized layers are composed of a nitrogen concentration gradient over several μm depth, and are expected to be useful for tribological applications with no adhesion problem. The nitriding method is tested on the synthesis of titanium nitride which is a well-known compound, obtained at present by many deposition and diffusion techniques. In the method of interest, a laser beam is focused on a titanium target in a nitrogen atmosphere, leading to the creation of a plasma over the metal surface. In order to understand the layer formation, it is necessary to characterize the plasma as well as the surface that it has been in contact with. Progressive nitrogen incorporation in the titanium lattice and TiN synthesis are studied by characterizing samples prepared with increasing laser shot number (100-4000). The role of the laser wavelength is also inspected by comparing layers obtained with two kinds of pulsed lasers: a transversal-excited-atmospheric-pressure-CO2 laser (λ=10.6 μm) and a XeCl excimer laser (λ=308 nm). Simulations of the target temperature rise under laser irradiation are performed, which evidence differences in the initial laser/material interaction (material heated thickness, heating time duration, etc.) depending on the laser features (wavelength and pulse time duration). Results from plasma characterization also point out that the plasma composition and propagation mode depend on the laser wavelength. Correlation of these results with those obtained from layer analyses shows at first the important role played by the plasma in the nitrogen incorporation. Its presence is necessary and allows N2 dissociation and a better energy coupling with the target. Second, it appears that the nitrogen diffusion governs the nitriding process. The study of the metal nitriding efficiency, depending on the laser used, allows us to explain the differences observed in the layer features

  18. Bioinspired Surface for Low Drag, Self-Cleaning, and Antifouling: Shark Skin, Butterfly and Rice Leaf Effects

    NASA Astrophysics Data System (ADS)

    Bixler, Gregroy D.

    In this thesis, first presented is an overview of inorganic-fouling and biofouling which is generally undesirable for many medical, marine, and industrial applications. A survey of nature's flora and fauna are studied in order to discover new antifouling methods that could be mimicked for engineering applications. New antifouling methods will presumably incorporate a combination of physical and chemical controls. Presented are mechanisms and experimental results focusing on laminar and turbulent drag reducing shark skin inspired riblet surfaces. This includes new laser etched and riblet film samples for closed channel drag using water, oil, and air as well as in wind tunnel. Also presented are mechanisms and experimental results focusing on the newly discovered rice and butterfly wing effect surfaces. Morphology, drag, self-cleaning, contact angle, and contact angle hysteresis data are presented to understand the role of sample geometrical dimensions, wettability, viscosity, and velocity. Hierarchical liquid repellent coatings combining nano- and micro-sized features and particles are utilized to recreate or combine various effects. Such surfaces have been fabricated with photolithography, soft lithography, hot embossing, and coating techniques. Discussion is provided along with new conceptual models describing the role of surface structures related to low drag, self-cleaning, and antifouling properties. Modeling provides design guidance when developing novel low drag and self-cleaning surfaces for medical, marine, and industrial applications.

  19. A short pulse, free running, Nd : YAG laser for the cleaning of stone cultural heritage

    NASA Astrophysics Data System (ADS)

    Mazzinghi, Piero; Margheri, Fabrizio

    2003-09-01

    This paper presents a Nd : YAG laser operating in free running (FR) regime, with a pulse duration (20 μs) shorter than conventional systems (>200 μs), mainly developed for applications in laser cleaning of stones, especially for the restoration of cultural heritage. The system was also optimized to achieve high energy and low divergence, for easy coupling with optical fibers. The unusual pulse temporal regime induces a spiky behavior of the laser output which could also help in the application. Details on the technologies for the flashlamps power supplies, including the discharge circuits needed to achieve the short pulses, are given. Application trials on artworks and artificial samples are also discussed. Results show that the intermediate pulse duration avoids the mechanical damage induced by the photomechanical effect of Q-switch lasers and the thermal damage, as superficial melting, usually induced by long pulse FR lasers.

  20. Optical Effects on Laser Ablated Polymer Surfaces

    NASA Astrophysics Data System (ADS)

    Prabhu, R. D.; Govinthasamy, R.; Murthy, N. S.

    2006-03-01

    Laser ablation of poly (ethylene terephthalate) and polyimide films were investigated using Excimer-UV laser. SEM analyses indicate the presence of rings for a wide range of ablation parameters (fluence, frequency and number of pulses). It is proposed that the particles present in the plasma plume could cause the incident laser light to diffract, similar to the optical effects observed in the femtosecond laser ablation of solids. The polymer surface provides a perfect medium to register the optical signatures as seen in the SEM images. The fringe-spacings observed in the images are compared with the theoretical diffraction patterns and the height of the plasma particles above the surface is estimated using an optimization scheme. The results of the analysis are consistent with experimentally observed dynamics of the plasma plume. It is proposed that such optical effects could be a routine feature in the laser ablation of polymers. The significance of such artifacts for lithography is discussed.

  1. Multiperiod-grating surface-emitting lasers

    NASA Technical Reports Server (NTRS)

    Lang, Robert J. (Inventor)

    1992-01-01

    Surface-emitting distributed feedback (DFB) lasers are disclosed with hybrid gratings. A first-order grating is provided at one or both ends of the active region of the laser for retroreflection of light back into the active region, and a second-order or nonresonant grating is provided at the opposite end for coupling light out perpendicular to the surfaces of the laser or in some other selected direction. The gratings may be curved to focus light retroreflected into the active region and to focus light coupled out to a point. When so focused to a point, the DFB laser may be part of a monolithic read head for a laser recorded disk, or an optical coupler into an optical fiber.

  2. Visible light surface emitting semiconductor laser

    DOEpatents

    Olbright, Gregory R.; Jewell, Jack L.

    1993-01-01

    A vertical-cavity surface-emitting laser is disclosed comprising a laser cavity sandwiched between two distributed Bragg reflectors. The laser cavity comprises a pair of spacer layers surrounding one or more active, optically emitting quantum-well layers having a bandgap in the visible which serve as the active optically emitting material of the device. The thickness of the laser cavity is m .lambda./2n.sub.eff where m is an integer, .lambda. is the free-space wavelength of the laser radiation and n.sub.eff is the effective index of refraction of the cavity. Electrical pumping of the laser is achieved by heavily doping the bottom mirror and substrate to one conductivity-type and heavily doping regions of the upper mirror with the opposite conductivity type to form a diode structure and applying a suitable voltage to the diode structure. Specific embodiments of the invention for generating red, green, and blue radiation are described.

  3. Laser surface conditioning of semimetallic friction materials

    SciTech Connect

    Patten, D.T.

    1986-01-01

    Surface conditioning is one way of reducing the duration and magnitude of the initial transients occurring in friction materials. In developing a laser searing system for semimetallic materials the changes occurring on the surface were characterized as a function of the power density. Excessive power melted the surface of the lining and produced an undesirable microstructure, while too little power did not produce the changes desired. The changes produced by laser searing were found to be similar to the changes produced by other types of surface conditioning. The friction and wear performance was studied for linings seared with different power densities. Laser searing primarily increased the low speed, low temperature, pre-burnish friction level. The amount of increase was proportional to the amount of searing. After burnishing the searing did not effect the friction level of the lining. Excessive power densities produced undesirable surface microstructures and persistent rotor scoring.

  4. In situ investigation of silicon surface cleaning and damage by argon electron cyclotron resonance plasmas

    NASA Astrophysics Data System (ADS)

    Hu, Y. Z.; Buaud, P. P.; Wang, Y.; Spanos, L.; Irene, E. A.

    1994-03-01

    An argon electron cyclotron resonance (ECR) plasma process has been optimized to successfully remove oxide films from a silicon surface at elevated temperatures leaving smooth Si surfaces devoid of an amorphized silicon damage layer. Etch rates of over 10 nm/min have been achieved at ion energies below 100 eV. The low ion energy (-50 V dc bias) and high ion fluxes (1×1016 ions/cm2 s) represent a significant improvement from conventional Ar ion sputter cleaning processes. In situ spectroscopic ellipsometry and ex situ atomic force microscopy were used to characterize the surface condition during and after cleaning to establish a 700 °C argon plasma cleaning process for silicon. Real-time single wavelength ellipsometry was used to study the cleaning kinetics, determine the optimal end point, and elucidate a controversy about the level of damage in the argon ECR plasma cleaning process.

  5. Composition control in laser surface alloying

    NASA Astrophysics Data System (ADS)

    Chande, T.; Mazumder, J.

    1983-06-01

    Laser surface alloying, a process of growing interest for local surface modification, relies upon a suitable composition and microstructure for satisfactory on-the-job performance. This paper reports the results of an initial systematic study of laser surface alloying nickel onto AISI 1020 steel substrates using a statistical experimental design technique. The objective was to relate processing conditions to dimensions, solute content, and microstructural refinement of the laser alloyed zones. Solute content was of principal concern as it is the single most important factor affecting the properties of laser surface alloys. The effects of varying the laser power, beam diameter, and speed on the width, depth, nickel content, and fluctuations in nickel content are reported. Interactions between process parameters are discussed, the reproducibility assessed, contour plots for solute content drawn. Dimensionless plots are developed that relate average solute content and microstructural refinement to process parameters. Previously published data for alloying chromium into 1018 steels are shown to contain similar trends. It is felt that such an approach would facilitate selection of processing conditions to obtain reproducibly the compositions and microstructures necessary for gainful utilization of laser surface alloys.

  6. Effect of defocusing distance on the contaminated surface of brass ring with nanosecond laser in a 3D laser scanning system

    NASA Astrophysics Data System (ADS)

    Zhao, Mali; Liu, Tiegen; Jiang, Junfeng; Wang, Meng

    2014-08-01

    Defocusing distance plays a key role in laser cleaning result and can be either positive or negative, depending on the focus position relative to the sample surface. In this paper, we investigate the effect of the defocusing distance on the cleaning efficiency of oxidized brass surface. The oxide layer from the surface of a brass ring was processed with a three dimensional (3-D) dynamically focused laser galvanometer scanning system. The relationship between removal efficiency of the oxide layer and the defocusing distance was analyzed. The sample surface topography, element content before and after the laser cleaning were analyzed by a scanning electron microscope (SEM) and Energy-dispersive X-ray spectroscopy (EDS), the surface quality after laser cleaning was analyzed by a Atomic Force Microscope (AFM), the chemical constituents of the oxide layer on the sample surface after being processed with different defocusing distances were examined by x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). The results show that the ratios of Cu/O and Zn/O reach the maximum of 53.2 and 27.78 respectively when the defocusing distance is +0.5 mm. The laser pulses will lose the ability to remove the oxide layer from the substrate surface when the defocusing distance is larger than ±2 mm.

  7. Self-Cleaning Surfaces: A Third-Year Undergraduate Research Project

    ERIC Educational Resources Information Center

    Haines, Ronald S.; Wu, Alex H. F.; Zhang, Hua; Coffey, Jacob; Huddle, Thomas; Lafountaine, Justin S.; Lim, Zhi-Jun; White, Eugene A.; Tuong, Nam T.; Lamb, Robert N.

    2009-01-01

    Superhydrophobic (non water-wettable) surfaces can possess the ability to self-clean (the so-called "lotus effect"). The task of devising the apparatus and method for quantifying this self-cleaning effect was offered as a project in a third-year undergraduate laboratory course. Using commonly available equipment the students devised a protocol for…

  8. Active cleaning techniques for removing contamination from optical surfaces in space

    NASA Technical Reports Server (NTRS)

    Shannon, R. L.; Gillette, R. B.

    1973-01-01

    Research in developing an active cleaning technique for removing contaminants from optical surfaces in space is reported. In situ contamination/cleaning experiments were conducted on gold and platimum coated mirrors, which were contaminated by exposure to UV radiation in a 1,3, butadiene environment. Argon and oxygen plasma exposure cleaned the mirrors equally well. Silicone cleaning experiments were also conducted. Exposure of the contaminated mirrors to helium, oxygen, and hydrogen plasmas restored the reflectance at the shorter wavelengths and degraded it at the longer wavelengths.

  9. Possibilities of a metal surface radioactive decontamination using a pulsed CO2 laser

    NASA Astrophysics Data System (ADS)

    Milijanic, Scepan S.; Stjepanovic, Natasa N.; Trtica, Milan S.

    2000-01-01

    There is a growing interest in the laser radioactive decontamination of metal surfaces. It offers advantages over conventional methods: improved safety, reduction of secondary waste, reduced waste volume, acceptable cost. A main mechanism of cleaning in by lasers is ablation. In this work a pulsed TEA CO2 laser was used for surface cleaning, primarily in order to demonstrate that the ablation from metal surfaces with this laser is possible even with relatively low pulse energies, and secondary, that it could be competitive with other lasers because of much higher energy efficiencies. The laser pulse contains two parts, one strong and shot peak at the beginning, followed with a tail. The beam was focused onto a contaminated surface with a KBr lens. The surface was contaminated with 137Cs. Three different metals were used: stainless steel, copper and aluminum. The evaporated material was pumped out in air atmosphere and transferred to a filter. Presence of the activity on the filter was proved by a germanium detector-multichannel analyzer. Activity levels were measured by a GM counter. Calculated decontamination factors as well as collection factors have shown that ablation takes place with relatively high efficiency of decontamination. This investigation suggests that decontamination using the CO2 laser should be seriously considered.

  10. NOVEL LASER ABLATION TECHNOLOGY FOR SURFACE DECONTAMINATION

    EPA Science Inventory

    The objective of this project is to develop a novel Laser Ablation Decontamination in Liquid (LADIL) technology for surface decontamination and safe removal of radioactive and/or toxic contaminants. It aims to achieve more efficient surface decontamination without secondary conta...

  11. Removal of dust particles from metal-mirror surfaces by excimer-laser radiation

    NASA Astrophysics Data System (ADS)

    Mann, Klaus R.; Wolff-Rottke, B.; Mueller, F.

    1995-07-01

    The effect of particle desorption from Al mirror surfaces by the influence of pulsed UV laser radiation has been studied. The investigations are closely related to the demands of astronomers, who are looking for a more effective way of cleaning the Al coatings of future very large telescope mirrors. A systematic parameter study has been performed in order to determine the irradiation conditions which yield the highest dust removal efficiency (i.e. reflectivity increase) on contaminated samples, taking particularly into account laser-induced damage and degradation effects of coating and substrate. The particle removal rate increases with increasing laser fluence, being limited however by the damage threshold of the coating. Therefore, parameters influencing the damage threshold of metal coatings like wavelength, pulse width, and number of pulses have been studied in detail. Data indicate that on Al coated BK7 and Zerodur samples KrF laser radiation yields the optimum result, with cleaning efficiencies comparable to polymer film stripping. The initial reflectivity of the clean coating can nearly be reinstalled, in particular when an additional solvent film on the sample surface is applied. Hence, laser desorption seems to be a viable method of cleaning large Al mirrors for telescopes.

  12. Vertical-Cavity Surface-Emitting Lasers

    NASA Astrophysics Data System (ADS)

    Wilmsen, Carl W.; Temkin, Henryk; Coldren, Larry A.

    2002-01-01

    1. Introduction to VCSELs L. A. Coldren, C. W. Wilmsen and H. Temkin; 2. Fundamental issues in VCSEL design L. A. Coldren and Eric R. Hegblom; 3. Enhancement of spontaneous emission in microcavities E. F. Schubert and N. E. J. Hunt; 4. Epitaxy of vertical-cavity lasers R. P. Schneider Jr and Y. H. Young; 5. Fabrication and performance of vertical-cavity surface-emitting lasers Kent D. Choquette and Kent Geib; 6. Polarization related properties of vertical cavity lasers Dmitri Kuksenkov and Henryk Temkin; 7. Visible light emitting vertical cavity lasers Robert L. Thornton; 8. Long-wavelength vertical-cavity lasers Dubrakovo I. Babic, Joachim Piprek and John E. Bowers; 9. Overview of VCSEL applications Richard C. Williamson; 10. Optical interconnection applications and required characteristics Kenichi Kasahara; 11. VCSEL-based fiber-optic data communications Kenneth Hahn and Kirk Giboney; 12. VCSEL-based smart pixels for free space optoelectronic processing C. W. Wilmsen.

  13. Method for Cleaning Laser-Drilled Holes on Printed Wiring Boards by Plasma Treatment

    NASA Astrophysics Data System (ADS)

    Hirogaki, Toshiki; Aoyama, Eiichi; Minagi, Ryu; Ogawa, Keiji; Katayama, Tsutao; Matsuoka, Takashi; Inoue, Hisahiro

    We propose a new method for cleaning blind via holes after laser drilling of PWBs using oxygen plasma treatment. This report dealt with three kinds of PWB materials: epoxy resin and two kinds of aramid fiber reinforced plastics (AFRP: Technora or Kevlar fiber reinforcement). We observed the drilled holes after plasma treatment using both an optical and a scanning electric microscope (SEM). It was confirmed that adequate etching took place in the drilled holes by plasma treatment. We also compared the hole wall and hole bottom after plasma treatment with ones after chemical etching. It was clear that there was no damage to the aramid fiber tip on the hole wall, and that a smooth roughness of the hole wall was obtained by means of plasma treatment. As a result, we demonstrated that the plasma treatment is effective in cleaning the laser drilled holes of PWBs.

  14. Laser restoring the glass surface treated with acid-based paint

    NASA Astrophysics Data System (ADS)

    Strusevich, Anastasia V.; Poltaev, Yuriy A.; Sinev, Dmitrii A.

    2013-11-01

    The modern city facilities are often being attacked by graffiti artists, and increasingly vandals leave "tags" using paints, which compound based on acids, hydrofluoric or acetic commonly. These paints not only ink the surface, but also increase the surface roughness, and such impact can not be corrected by conventional cleaning. Thus, it was requested to develop technology that would not only clean the surface, but also to restore its structure by smoothing out irregularities and roughness formed after exposure in acid. In this work we investigated the effect of restoring the surface of the glass, spoiled by acid-based paint and then treated with CO2-laser. During the experiments, it was found that it is real to create the single-step laser surface restoring technology.

  15. Self-cleaning of superhydrophobic surfaces by self-propelled jumping condensate

    PubMed Central

    Wisdom, Katrina M.; Qu, Xiaopeng; Liu, Fangjie; Watson, Gregory S.; Chen, Chuan-Hua

    2013-01-01

    The self-cleaning function of superhydrophobic surfaces is conventionally attributed to the removal of contaminating particles by impacting or rolling water droplets, which implies the action of external forces such as gravity. Here, we demonstrate a unique self-cleaning mechanism whereby the contaminated superhydrophobic surface is exposed to condensing water vapor, and the contaminants are autonomously removed by the self-propelled jumping motion of the resulting liquid condensate, which partially covers or fully encloses the contaminating particles. The jumping motion off the superhydrophobic surface is powered by the surface energy released upon coalescence of the condensed water phase around the contaminants. The jumping-condensate mechanism is shown to spontaneously clean superhydrophobic cicada wings, where the contaminating particles cannot be removed by gravity, wing vibration, or wind flow. Our findings offer insights for the development of self-cleaning materials. PMID:23630277

  16. Composite Resonator Surface Emitting Lasers

    SciTech Connect

    FISCHER,ARTHUR J.; CHOQUETTE,KENT D.; CHOW,WENG W.; ALLERMAN,ANDREW A.; GEIB,KENT M.

    2000-05-01

    The authors have developed electrically-injected coupled-resonator vertical-cavity lasers and have studied their novel properties. These monolithically grown coupled-cavity structures have been fabricated with either one active and one passive cavity or with two active cavities. All devices use a selectively oxidized current aperture in the lower cavity, while a proton implant was used in the active-active structures to confine current in the top active cavity. They have demonstrated optical modulation from active-passive devices where the modulation arises from dynamic changes in the coupling between the active and passive cavities. The laser intensity can be modulated by either forward or reverse biasing the passive cavity. They have also observed Q-switched pulses from active-passive devices with pulses as short as 150 ps. A rate equation approach is used to model the Q-switched operation yielding good agreement between the experimental and theoretical pulseshape. They have designed and demonstrated the operation of active-active devices which la.se simultaneously at both longitudinal cavity resonances. Extremely large bistable regions have also been observed in the light-current curves for active-active coupled resonator devices. This bistability can be used for high contrast switching with contrast ratios as high as 100:1. Coupled-resonator vertical-cavity lasers have shown enhanced mode selectivity which has allowed devices to lase with fundamental-mode output powers as high as 5.2 mW.

  17. Effect of cleaning and sterilization on titanium implant surface properties and cellular response

    PubMed Central

    Park, Jung Hwa; Olivares-Navarrete, Rene; Baier, Robert E.; Meyer, Anne E.; Tannenbaum, Rina; Boyan, Barbara D.; Schwartz, Zvi

    2013-01-01

    Titanium (Ti) has been widely used as an implant material due to the excellent biocompatibility and corrosion resistance of its oxide surface. Biomaterials must be sterile before implantation, but the effects of sterilization on their surface properties have been less well studied. The effects of cleaning and sterilization on surface characteristics were bio-determined using contaminated and pure Ti substrata first manufactured to present two different surface structures: pretreated titanium (PT, Ra = 0.4 μm) (i.e. surfaces that were not modified by sandblasting and/or acid etching); (SLA, Ra = 3.4 μm). Previously cultured cells and associated extracellular matrix were removed from all bio-contaminated specimens by cleaning in a sonicator bath with a sequential acetone–isopropanol–ethanol–distilled water protocol. Cleaned specimens were sterilized with autoclave, gamma irradiation, oxygen plasma, or ultraviolet light. X-ray photoelectron spectroscopy (XPS), contact angle measurements, profilometry, and scanning electron microscopy were used to examine surface chemical components, hydrophilicity, roughness, and morphology, respectively. Small organic molecules present on contaminated Ti surfaces were removed with cleaning. XPS analysis confirmed that surface chemistry was altered by both cleaning and sterilization. Cleaning and sterilization affected hydrophobicity and roughness. These modified surface properties affected osteogenic differentiation of human MG63 osteoblast-like cells. Specifically, autoclaved SLA surfaces lost the characteristic increase in osteoblast differentiation seen on starting SLA surfaces, which was correlated with altered surface wettability and roughness. These data indicated that recleaned and resterilized Ti implant surfaces cannot be considered the same as the first surfaces in terms of surface properties and cell responses. Therefore, the reuse of Ti implants after resterilization may not result in the same tissue responses as

  18. From the Lab to the Scaffold: Laser Cleaning of Polychromed Architectonic Elements and Sculptures

    NASA Astrophysics Data System (ADS)

    Castillejo, M.; Domingo, C.; Guerra-Librero, F.; Jadraque, M.; Martín, M.; Oujja, M.; Rebollar, E.; Torres, R.

    This work presents the results of laboratory tests aiming at the characterization of painting materials by LIB and FT-Raman spectroscopies and at identification of the best laser cleaning conditions of polychromes of Spanish Heritage: polychromes on gypsum mortar of the Church-Fortress of Santa Tecla of Cervera de la Cañada, Zaragoza, fifteenth century, and appliqué relief brocades on wooden sculptures of the Chapel of San Miguel, Cathedral of Jaca, Huesca, sixteenth century.

  19. Excimer laser induced nanostructuring of silicon surfaces.

    PubMed

    Kumar, Prashant; Krishna, Mamidipudi Ghanashyam; Bhattacharya, Ashok

    2009-05-01

    The effect of KrF excimer laser energy density (below and above the ablation threshold), number of shots and angle of laser incidence on the morphological reconstruction, structure and specular reflectance of Si[311] surfaces is reported. At low energy densities (0.1 to 0.3 J/cm2) laser irradiation results in a variety of nanostructures, depending on laser energy density and number of shots, such as nanopores (40-60 nm dia) and nanoparticles (40-80 nm dia). At energies greater than the laser ablation threshold (2 to 5 J/cm2) the formation of nanowires (200 nm dia, 6-8 microm length), and closely spaced silicon nanograins (100-150 nm dia) is observed. Experiments to study the effect of laser irradiation in the proximity of a fixed shape such as a linear step edge in the form of a stainless steel blade and a cylindrical cross-section Cu wire were also carried out. In both cases, linearly organized nanoparticles (150-200 nm diameter) and nanowires (60-80 nm diameter) formed close to the edge. There is a systematic degradation of long-range order with the number of shots and laser energy density as evidenced from X-ray diffraction studies. At an energy density of 2 J/cm2, and 100 shots the [311] oriented silicon surface made a transition to a randomly oriented nanocrystalline state. PMID:19452995

  20. Hard Surface Biocontrol in Hospitals Using Microbial-Based Cleaning Products

    PubMed Central

    Vandini, Alberta; Temmerman, Robin; Frabetti, Alessia; Caselli, Elisabetta; Antonioli, Paola; Balboni, Pier Giorgio; Platano, Daniela; Branchini, Alessio; Mazzacane, Sante

    2014-01-01

    Background Healthcare-Associated Infections (HAIs) are one of the most frequent complications occurring in healthcare facilities. Contaminated environmental surfaces provide an important potential source for transmission of many healthcare-associated pathogens, thus indicating the need for new and sustainable strategies. Aim This study aims to evaluate the effect of a novel cleaning procedure based on the mechanism of biocontrol, on the presence and survival of several microorganisms responsible for HAIs (i.e. coliforms, Staphyloccus aureus, Clostridium difficile, and Candida albicans) on hard surfaces in a hospital setting. Methods The effect of microbial cleaning, containing spores of food grade Bacillus subtilis, Bacillus pumilus and Bacillus megaterium, in comparison with conventional cleaning protocols, was evaluated for 24 weeks in three independent hospitals (one in Belgium and two in Italy) and approximately 20000 microbial surface samples were collected. Results Microbial cleaning, as part of the daily cleaning protocol, resulted in a reduction of HAI-related pathogens by 50 to 89%. This effect was achieved after 3–4 weeks and the reduction in the pathogen load was stable over time. Moreover, by using microbial or conventional cleaning alternatively, we found that this effect was directly related to the new procedure, as indicated by the raise in CFU/m2 when microbial cleaning was replaced by the conventional procedure. Although many questions remain regarding the actual mechanisms involved, this study demonstrates that microbial cleaning is a more effective and sustainable alternative to chemical cleaning and non-specific disinfection in healthcare facilities. Conclusions This study indicates microbial cleaning as an effective strategy in continuously lowering the number of HAI-related microorganisms on surfaces. The first indications on the actual level of HAIs in the trial hospitals monitored on a continuous basis are very promising, and may pave the

  1. Laser-induced periodic annular surface structures on fused silica surface

    SciTech Connect

    Liu, Yi; Brelet, Yohann; Forestier, Benjamin; Houard, Aurelien; Yu, Linwei; Deng, Yongkai; Jiang, Hongbing

    2013-06-24

    We report on the formation of laser-induced periodic annular surface structures on fused silica irradiated with multiple femtosecond laser pulses. This surface morphology emerges after the disappearance of the conventional laser induced periodic surface structures, under successive laser pulse irradiation. It is independent of the laser polarization and universally observed for different focusing geometries. We interpret its formation in terms of the interference between the reflected laser field on the surface of the damage crater and the incident laser pulse.

  2. Superhydrophobic and self-cleaning bio-fiber surfaces via ATRP and subsequent postfunctionalization.

    PubMed

    Nyström, Daniel; Lindqvist, Josefina; Ostmark, Emma; Antoni, Per; Carlmark, Anna; Hult, Anders; Malmström, Eva

    2009-04-01

    Superhydrophobic and self-cleaning cellulose surfaces have been obtained via surface-confined grafting of glycidyl methacrylate using atom transfer radical polymerization combined with postmodification reactions. Both linear and branched graft-on-graft architectures were used for the postmodification reactions to obtain highly hydrophobic bio-fiber surfaces by functionalization of the grafts with either poly(dimethylsiloxane), perfluorinated chains, or alkyl chains, respectively. Postfunctionalization using alkyl chains yielded results similar to those of surfaces modified by perfluorination, in terms of superhydrophobicity, self-cleaning properties, and the stability of these properties over time. In addition, highly oleophobic surfaces have been obtained when modification with perfluorinated chains was performed. PMID:20356007

  3. Preparation of clean InP(100) surfaces studied by synchrotron radiation photoemission

    NASA Astrophysics Data System (ADS)

    Sun, Yun; Liu, Zhi; Machuca, Francisco; Pianetta, Piero; Spicer, William E.

    2003-01-01

    The chemical cleaning of indium phosphide (InP),(100) surfaces is studied systematically by using photoemission electron spectroscopy. In order to achieve the necessary surface sensitivity and spectral resolution, synchrotron radiation with photon energies ranging from 60 to 600 eV are used to study the indium 4d, phosphorus 2p, carbon 1s, and oxygen 1s core levels, and the valence band. Typical H2SO4:H2O2:H2O solutions used to etch GaAs(100) surfaces are applied to InP(100) surfaces. It is found that the resulting surface species are significantly different from those found on GaAs(100) surfaces and that a second chemical cleaning step using a strong acid is required to remove residual surface oxide. This two-step cleaning process leaves the surface oxide free and with approximately 0.4 ML of elemental phosphorus, which is removed by vacuum annealing. The carbon coverage is also reduced dramatically from approximately 1 to about 0.05 ML. The chemical reactions are investigated, the resulting InP surface species at different cleaning stages are determined, and the optimum cleaning procedure is presented.

  4. The measurement of surface roughness to determine the suitability of different methods for stone cleaning

    NASA Astrophysics Data System (ADS)

    Vazquez-Calvo, Carmen; Alvarez de Buergo, Monica; Fort, Rafael; Varas-Muriel, Maria Jose

    2012-08-01

    The roughness of stone surface was measured, before and after bead blasting-based cleaning methods, to select the most efficient one to be used in masonry and stonework of specific areas of the Cathedral of Segovia (Spain). These types of cleaning methods can, besides the removal of soiling and surface deposits, leave a rougher surface, which would mean higher and more rapid water retention and deposit accumulation due to a specific surface increase, therefore accelerating stone decay. Or, in contrast, the cleaning method can be so aggressive that it can smooth the surface by reducing its roughness, a fact that usually corresponds to excessive material removal—soot and deposits--but also part of the stone substrate. Roughness results were complemented with scanning electron microscopy observations and analyses and colour measurements. Finally, it was possible to select the best cleaning method among the six that were analysed, for different areas and different stone materials. Therefore, this study confirms the measurement of surface roughness as a reliable test to determine the suitability of stone cleaning methods; it is a non-destructive technique, portable and friendly to use, which can help us to rapidly assess—together with other techniques—the efficacy and aggressiveness of the stone cleaning method.

  5. The influence and use of the SFR or LQS Nd:YAG laser beam on the cleaning and restoration of two diverse church facades

    NASA Astrophysics Data System (ADS)

    Catalano, Ida M.; Andriani, S. E.; Laviano, R.; Vona, F.; Daurelio, Giuseppe; Stea, G.

    2005-03-01

    The present experimental study and job, still in progress, were conceived not only for an evaluation of the effectiveness of laser cleaning technique but also for comparing two different laser pulse duration of a Nd:YAG laser: Short Free Running (SFR) with a pulse duration of td=20μs and Long Q-Switched (LQS) with a pulse duration of td=70ns. The samples were carried out by the facades of teh Cathedral of Troia and of the Church of Molfetta, both in the South of Italy. All laser cleaning experiments were carried out in "wet condition" by using some distilled water on the encrustation before the irradiation. Surface analytical techniques, such as Optical Microscopy (OM), X-Ray Diffraction (XRD), Fourier-Transform InfraRed spectroscopy (FTIR), and Scanning Electron Microscopy (SEM) coupled with Energy Xpray Dispersive analysis (EDX)were used to detect crust chemical composition and morphology, as well as, to monitor the effects induced by the laser treatments. On the basis of these structural and analytical examinations, both the lasers have shown to be appropriate for achieving a sufficient removal of the selected layers without modifying the surface morphology and keeping the preservation of the "patina/treatment" layer.

  6. Laser-induced gas-surface interactions

    NASA Astrophysics Data System (ADS)

    Chuang, T. J.

    Chemical reactions in homogeneous systems activated by laser radiation have been extensively investigated for more than a decade. The applications of lasers to promote gas-surface interactions have just been realized in recent years. The purpose of this paper is to examine the fundamental processes involved in laser-induced gas-surface chemical interactions. Specifically, the photon-enhanced adsorption, adsorbate-adsorbate and adsorbate-solid reactions, product formation and desorption processes are discussed in detail. The dynamic processes involved in photoexcitation of the electronic and vibrational states, the energy transfer and relaxation in competition with chemical interactions are considered. These include both single and multiple photon adsorption, and fundamental and overtone transitions in the excitation process, and inter- and intra-molecular energy transfer, and coupling with phonons, electron-hole pairs and surface plasmons in the energy relaxation process. Many current experimental and theoretical studies on the subject are reviewed and discussed with the goal of clarifying the relative importance of the surface interaction steps and relating the resulting concepts to the experimentally observed phenomena. Among the many gas-solid systems that have been investigated, there has been more extensive use of CO adsorbed on metals, and SF 6 and XeF 2 interactions with silicon as examples to illustrate the many facets of the electronically and vibrationally activated surface processes. Results on IR laser stimulated desorption of C 5H 5N and C 5D 5N molecules from various solid surfaces are also presented. It is clearly shown that rapid intermolecular energy exchange and molecule to surface energy transfer can have important effects on photodesorption cross sections and isotope selectivities. It is concluded that utilization of lasers in gas-surface studies not only can provide fundamental insight into the mechanism and dynamics involved in heterogeneous

  7. Investigation of EUV haze defect: molecular behaviors of mask cleaning chemicals on EUV mask surfaces

    NASA Astrophysics Data System (ADS)

    Choi, Jaehyuck; Novak, Steve; Kandel, Yudhishthir; Denbeaux, Greg; Lee, Han-shin; Ma, Andy; Goodwin, Frank

    2012-03-01

    Photo-induced defects (or haze defects) on 193nm optic masks (haze defects) have been a serious problem not only to reticle engineers working for mask manufacturing and handling but also to photo-lithography engineers. The most widely accepted explanation of the root causes of haze defects is the cleaning chemical residues remaining on the mask surface and unavoidable outgassed molecules that outgas from pellicle materials when exposed to 193nm radiation. These have been significant challenges for reticle cleaning engineers who need to use cleaning chemicals whose residues do not lead to progressive defect formation on the mask and to find improved materials to minimize pellicle outgassing. It is assumed that contamination generation on EUV masks would have a higher probability than on optic masks, primarily since EUV masks are not protected by a pellicle and amorphous carbon films can accumulate during exposure to EUV light. While there is potential to mitigate the generation of carbon contamination by improving the exposure tool environment and removing carbon films using in-situ atomic hydrogen cleaning, it is not yet clear whether the reaction of mask cleaning chemicals to EUV radiation will lead to creation of progressive defects on EUV mask surfaces. With the work to being done it has been observed that carbon contamination on EUV masks dominates any effects of solvent chemicals under normal environmental or exposure conditions (from atmospheric pressure up to a vacuum level of 10-6 Torr) during EUV exposure. However, it is still unknown whether residual cleaning chemicals will provide a nucleus for progressive defect formation during exposure. This lack of understanding needs to be addressed by the industry as EUV masks are expected to undergo more frequent cleaning cycles. In this work, we will report on an investigation of the molecular behavior of cleaning chemicals on EUV mask surfaces during EUV exposure. Movement (e.g., migration or aggregation) of

  8. Self-Partitioned Droplet Array on Laser-Patterned Superhydrophilic Glass Surface for Wall-less Cell Arrays.

    PubMed

    Xu, Kerui; Wang, Xiaopu; Ford, Roseanne M; Landers, James P

    2016-03-01

    In this work, we report a novel method for the creation of superhydrophilic patterns on the surface of hydrophobically coated glass through CO2 laser cleaning. This mask-free approach requires no photolithography for the print of the features, and only a single-step surface pretreatment is needed. The laser-cleaned glass surface enables self-partitioning of liquid into droplet arrays with controllable, quantitative volumes. We further designed wall-less cell arrays for the mapping of culturing conditions and demonstrated the potential of this droplet-arraying method. PMID:26878418

  9. Laser Induced Aluminum Surface Breakdown Model

    NASA Technical Reports Server (NTRS)

    Chen, Yen-Sen; Liu, Jiwen; Zhang, Sijun; Wnag, Ten-See (Technical Monitor)

    2001-01-01

    Laser powered propulsion systems involve complex fluid dynamics, thermodynamics and radiative transfer processes. Based on an unstructured grid., pressure-based computational aerothermodynamics, platform, several sub-nio"'dels describing such underlying physics as laser ray tracing and focusing, thermal non-equilibrium, plasma radiation and air spark ignition have been developed. This proposed work shall extend the numerical platform and existing sub-models to include the aluminum wall surface Inverse Bremsstrahlung (113) effect from which surface ablation and free-electron generation can be initiated without relying on the air spark ignition sub-model. The following tasks will be performed to accomplish the research objectives.

  10. Laser Induced Aluminum Surface Breakdown Model

    NASA Technical Reports Server (NTRS)

    Chen, Yen-Sen; Liu, Jiwen; Zhang, Sijun; Wang, Ten-See (Technical Monitor)

    2002-01-01

    Laser powered propulsion systems involve complex fluid dynamics, thermodynamics and radiative transfer processes. Based on an unstructured grid, pressure-based computational aerothermodynamics; platform, several sub-models describing such underlying physics as laser ray tracing and focusing, thermal non-equilibrium, plasma radiation and air spark ignition have been developed. This proposed work shall extend the numerical platform and existing sub-models to include the aluminum wall surface Inverse Bremsstrahlung (IB) effect from which surface ablation and free-electron generation can be initiated without relying on the air spark ignition sub-model. The following tasks will be performed to accomplish the research objectives.

  11. Influence of lasing parameters on the cleaning efficacy of laser-activated irrigation with pulsed erbium lasers.

    PubMed

    Meire, Maarten A; Havelaerts, Sophie; De Moor, Roeland J

    2016-05-01

    Laser-activated irrigation (LAI) using erbium lasers is an irrigant agitation technique with great potential for improved cleaning of the root canal system, as shown in many in vitro studies. However, lasing parameters for LAI vary considerably and their influence remains unclear. Therefore, this study sought to investigate the influence of pulse energy, pulse frequency, pulse length, irradiation time and fibre tip shape, position and diameter on the cleaning efficacy of LAI. Transparent resin blocks containing standardized root canals (apical diameter of 0.4 mm, 6 % taper, 15 mm long, with a coronal reservoir) were used as the test model. A standardized groove in the apical part of each canal wall was packed with stained dentin debris. The canals were filled with irrigant, which was activated by an erbium: yttrium aluminium garnet (Er:YAG) laser (2940 nm, AT Fidelis, Fotona, Ljubljana, Slovenia). In each experiment, one laser parameter was varied, while the others remained constant. In this way, the influence of pulse energy (10-40 mJ), pulse length (50-1000 μs), frequency (5-30 Hz), irradiation time (5-40 s) and fibre tip shape (flat or conical), position (pulp chamber, canal entrance, next to groove) and diameter (300-600 μm) was determined by treating 20 canals per parameter. The amount of debris remaining in the groove after each LAI procedure was scored and compared among the different treatments. The parameters significantly (P < 0.05, Kruskal-Wallis) affecting debris removal from the groove were fibre tip position, pulse length, pulse energy, irradiation time and frequency. Fibre tip shape and diameter had no significant influence on the cleaning efficacy. PMID:26861988

  12. Study of the surface cleaning of GOI and SGOI substrates for Ge epitaxial growth

    NASA Astrophysics Data System (ADS)

    Moriyama, Yoshihiko; Hirashita, Norio; Usuda, Koji; Nakaharai, Shu; Sugiyama, Naoharu; Toyoda, Eiji; Takagi, Shin-ichi

    2009-11-01

    An effective wet cleaning process, optimized for low temperature Ge epitaxial growth on thin Ge or SiGe structures with reduced surface roughening, is proposed. It is found that HF + HCl cleaning is the most effective wet cleaning method that is applicable to the low temperature thermal cleaning. It is also found that temperature of the thermal cleaning appropriate to 25-30 nm thick germanium on insulator (GOI) or silicon-germanium on insulator (SGOI) substrates is approximately 450 °C. Moreover, it is also found that the temperatures of Ge epitaxial growth even in lattice-matched systems must be reduced to around 400 °C to prevent surface roughening and those in lattice-mismatched systems also must be reduced sufficiently (300 °C for strained Ge growth on SGOI ( Xeff = 0.6)) to prevent lattice relaxation as well as surface roughening. Finally, the successful formation of the compressively strained GOI structures is demonstrated by applying these wet cleaning and low temperature thermal cleaning processes and low temperature Ge epitaxy to thin SGOI substrates.

  13. Laser interaction with coated collagen and cellulose fibre composites: fundamentals of laser cleaning of ancient parchment manuscripts and paper

    NASA Astrophysics Data System (ADS)

    Kautek, Wolfgang; Pentzien, Simone; Rudolph, Pascale; Krüger, Jörg; König, Eberhard

    1998-05-01

    Laser cleaning of delicate biological composite materials such as ancient parchment manuscripts from the 15th and 16th century and printed paper from the 19th century is demonstrated with an ultraviolet excimer pulsed laser at 308 nm. Laser fluence levels must stay below the ablation and destruction threshold of the parchment or paper substrate, and have to surpass the threshold of the contaminant matter. Foreign layers to be removed must exhibit a higher optical density than the artifact substrates. Synthetic carbonaceous dirt modelled by water-soluble black crayons showed a characteristically weak featureless laser-induced plasma spectroscopy spectrum near the noise limit. It turned out that laser-induced plasma spectroscopy is of limited use in monitoring halting points (or etch-stops) because it relies on the destruction not only of the laterally inhomogenously distributed contaminant but also of pigment phases on a microscopically rough parchment substrate. Laser-induced fluorescence spectroscopy, however, promises to be a valuable non-destructive testing technique for etch-stop monitoring.

  14. Surface ozone exposures measured at clean locations around the world.

    PubMed

    Lefohn, A S; Krupa, S V; Winstanley, D

    1990-01-01

    For assessing the effects of air pollution on vegetation, some researchers have used control chambers as the basis of comparison between crops and trees grown in contemporary polluted rural locations and those grown in a clean environment. There has been some concern whether the arbitrary ozone level of 0.025 ppm and below, often used in charcoal-filtration chambers to simulate the natural background concentration of ozone, is appropriate. Because of the many complex and man-made factors that influence ozone levels, it is difficult to determine natural background. To identify a range of ozone exposures that occur at 'clean' sites, we have calculated ozone exposures observed at a number of 'clean' monitoring sites located in the United States and Canada. We do not claim that these sites are totally free from human influence, but rather than the ozone concentrations observed at these 'clean' sites may be appropriate for use by vegetation researchers in control chambers as pragmatic and defensible surrogates for natural background. For comparison, we have also calculated ozone exposures observed at four 'clean' remote sites in the Northern and Southern Hemispheres and at two remote sites (Whiteface Mountain, NY and Hohenpeissenberg, FRG) that are considered to be more polluted. Exposure indices relevant for describing the relationship between ozone and vegetation effects were applied. For studying the effects of ozone on vegetation, the higher concentrations are of interest. The sigmoidally-weighted index appeared to best separate those sites that experienced frequent high concentration exposures from those that experienced few high concentrations. Although there was a consistent seasonal pattern for the National Oceanic and Atmospheric Administration (NOAA) Geophysical Monitoring for Climate Change (GMCC) sites indicating a winter/spring maximum, this was not the case for the other remote sites. Some sites in the continental United States and southern Canada

  15. Excimer laser irradiation of metal surfaces

    NASA Astrophysics Data System (ADS)

    Kinsman, Grant

    In this work a new method of enhancing CO2 laser processing by modifying the radiative properties of a metal surface is studied. In this procedure, an excimer laser (XeCl) or KrF) exposes the metal surface to overlapping pulses of high intensity, 10(exp 8) - 10(exp 9) W cm(exp -2), and short pulse duration, 30 nsec FWHM (Full Width Half Maximum), to promote structural and chemical change. The major processing effect at these intensities is the production of a surface plasma which can lead to the formation of a laser supported detonation wave (LSD wave). This shock wave can interact with the thin molten layer on the metal surface influencing to a varying degree surface oxidation and roughness features. The possibility of the expulsion, oxidation and redeposition of molten droplets, leading to the formation of micron thick oxide layers, is related to bulk metal properties and the incident laser intensity. A correlation is found between the expulsion of molten droplets and a Reynolds number, showing the interaction is turbulent. The permanent effects of these interactions on metal surfaces are observed through scanning electron microscopy (SEM), transient calorimetric measurements and Fourier transform infrared (FTIR) spectroscopy. Observed surface textures are related to the scanning procedures used to irradiate the metal surface. Fundamental radiative properties of a metal surface, the total hemispherical emissivity, the near-normal spectral absorptivity, and others are examined in this study as they are affected by excimer laser radiation. It is determined that for heavily exposed Al surface, alpha' (10.6 microns) can be increased to values close to unity. Data relating to material removal rates and chemical surface modification for excimer laser radiation is also discussed. The resultant reduction in the near-normal reflectivity solves the fundamental problem of coupling laser radiation into highly reflective and conductive metals such as copper and aluminum. The

  16. Process for laser machining and surface treatment

    DOEpatents

    Neil, George R.; Shinn, Michelle D.

    2004-10-26

    An improved method and apparatus increasing the accuracy and reducing the time required to machine materials, surface treat materials, and allow better control of defects such as particulates in pulsed laser deposition. The speed and quality of machining is improved by combining an ultrashort pulsed laser at high average power with a continuous wave laser. The ultrashort pulsed laser provides an initial ultrashort pulse, on the order of several hundred femtoseconds, to stimulate an electron avalanche in the target material. Coincident with the ultrashort pulse or shortly after it, a pulse from a continuous wave laser is applied to the target. The micromachining method and apparatus creates an initial ultrashort laser pulse to ignite the ablation followed by a longer laser pulse to sustain and enlarge on the ablation effect launched in the initial pulse. The pulse pairs are repeated at a high pulse repetition frequency and as often as desired to produce the desired micromachining effect. The micromachining method enables a lower threshold for ablation, provides more deterministic damage, minimizes the heat affected zone, minimizes cracking or melting, and reduces the time involved to create the desired machining effect.

  17. Repellent materials. Robust self-cleaning surfaces that function when exposed to either air or oil.

    PubMed

    Lu, Yao; Sathasivam, Sanjayan; Song, Jinlong; Crick, Colin R; Carmalt, Claire J; Parkin, Ivan P

    2015-03-01

    Superhydrophobic self-cleaning surfaces are based on the surface micro/nanomorphologies; however, such surfaces are mechanically weak and stop functioning when exposed to oil. We have created an ethanolic suspension of perfluorosilane-coated titanium dioxide nanoparticles that forms a paint that can be sprayed, dipped, or extruded onto both hard and soft materials to create a self-cleaning surface that functions even upon emersion in oil. Commercial adhesives were used to bond the paint to various substrates and promote robustness. These surfaces maintained their water repellency after finger-wipe, knife-scratch, and even 40 abrasion cycles with sandpaper. The formulations developed can be used on clothes, paper, glass, and steel for a myriad of self-cleaning applications. PMID:25745169

  18. Robust self-cleaning surfaces that function when exposed to either air or oil

    NASA Astrophysics Data System (ADS)

    Lu, Yao; Sathasivam, Sanjayan; Song, Jinlong; Crick, Colin R.; Carmalt, Claire J.; Parkin, Ivan P.

    2015-03-01

    Superhydrophobic self-cleaning surfaces are based on the surface micro/nanomorphologies; however, such surfaces are mechanically weak and stop functioning when exposed to oil. We have created an ethanolic suspension of perfluorosilane-coated titanium dioxide nanoparticles that forms a paint that can be sprayed, dipped, or extruded onto both hard and soft materials to create a self-cleaning surface that functions even upon emersion in oil. Commercial adhesives were used to bond the paint to various substrates and promote robustness. These surfaces maintained their water repellency after finger-wipe, knife-scratch, and even 40 abrasion cycles with sandpaper. The formulations developed can be used on clothes, paper, glass, and steel for a myriad of self-cleaning applications.

  19. Particle size distribution on surfaces in clean rooms. Final technical report September 1983-February 1984

    SciTech Connect

    Hamberg, O.; Shon, E.M.

    1984-04-30

    Experimental particle size distributions of surfaces in clean rooms, resulting from the gravity settling of airborne particulates (fallout), are presented and found to be significantly different from the distributions described by Military Standard 1246A. Theoretical surface size distributions, based on fallout from a Federal Standard 209B airborne particle distribution, are derived and show good correlation with experimental data. Further experimental data and analysis are provided to show that surface cleaning tends to make a particle size distribution resulting from fallout approach the MIL-STD-1246A distribution. Recommendations are made to limit the use of MIL-STD-1246A, when specifying surface cleanliness levels, to surfaces that have been cleaned after exposure to fallout.

  20. Impact of different cleaning processes on the laser damage threshold of antireflection coatings for Z-Backlighter optics at Sandia National Laboratories

    SciTech Connect

    Field, Ella; Bellum, John; Kletecka, Damon

    2014-11-06

    We have examined how different cleaning processes affect the laser-induced damage threshold of antireflection coatings for large dimension, Z-Backlighter laser optics at Sandia National Laboratories. Laser damage thresholds were measured after the coatings were created, and again 4 months later to determine which cleaning processes were most effective. There is a nearly twofold increase in laser-induced damage threshold between the antireflection coatings that were cleaned and those that were not cleaned. Aging of the coatings after 4 months resulted in even higher laser-induced damage thresholds. Also, the laser-induced damage threshold results revealed that every antireflection coating had a high defect density, despite the cleaning process used, which indicates that improvements to either the cleaning or deposition processes should provide even higher laser-induced damage thresholds.

  1. Impact of different cleaning processes on the laser damage threshold of antireflection coatings for Z-Backlighter optics at Sandia National Laboratories

    DOE PAGESBeta

    Field, Ella; Bellum, John; Kletecka, Damon

    2014-11-06

    We have examined how different cleaning processes affect the laser-induced damage threshold of antireflection coatings for large dimension, Z-Backlighter laser optics at Sandia National Laboratories. Laser damage thresholds were measured after the coatings were created, and again 4 months later to determine which cleaning processes were most effective. There is a nearly twofold increase in laser-induced damage threshold between the antireflection coatings that were cleaned and those that were not cleaned. Aging of the coatings after 4 months resulted in even higher laser-induced damage thresholds. Also, the laser-induced damage threshold results revealed that every antireflection coating had a high defectmore » density, despite the cleaning process used, which indicates that improvements to either the cleaning or deposition processes should provide even higher laser-induced damage thresholds.« less

  2. Laser Assisted Cancer Immunotherapy: Surface Irradiation

    NASA Astrophysics Data System (ADS)

    Wilson, Joshua; Chen, Hsin-Wei; Bandyopadhyay, Pradip

    2006-03-01

    Experiments in our laboratory incorporate a non-invasive approach to treat superficial tumors in animal models. Based on the concept of Laser Assisted Cancer Immunotherapy, surface irradiation provides good information to compare to invasive alternatives. The procedure involves injecting an immunoadjuvant (Glycated Chitosan) as well as a light absorbing dye (Indocyanine Green) directly into the tumor (5 to 7 mm in diameter). The temperature of the tumor is raised using an infrared diode laser operating at 804 nm, with a silica fiber tip placed a set distance away from the surface of the tumor. We monitor the surface temperature using non-invasive (infrared detector probe) as well as the internal temperature of the tumor using invasive (micro thermocouples) methods. This study aims at the success of the surface irradiation mode to treat solid tumors. * This work is supported by a grant from The National Institute of Health.

  3. Pulsed laser surface hardening of ferrous alloys.

    SciTech Connect

    Xu, Z.; Reed, C. B.; Leong, K. H.; Hunter, B. V.

    1999-09-30

    A high power pulsed Nd:YAG laser and special optics were used to produce surface hardening on 1045 steel and gray cast iron by varying the process parameters. Unlike CO{sub 2} lasers, where absorptive coatings are required, the higher absorptivity of ferrous alloys at the Nd:YAG laser wavelength eliminates the necessity of applying a coating before processing. Metallurgical analysis of the treated tracks showed that very fine and hard martensitic microstructure (1045 steel) or inhomogeneous martensite (gray cast iron) were obtained without surface melting, giving maximum hardness of HRC 61 and HRC 40 for 1045 steel and gray cast iron respectively. The corresponding maximum case depths for both alloys at the above hardness are 0.6 mm. Gray cast iron was more difficult to harden without surface melting because of its lower melting temperature and a significantly longer time-at-temperature required to diffuse carbon atoms from the graphite flakes into the austenite matrix during laser heating. The thermal distortion was characterized in term of flatness changes after surface hardening.

  4. Establishing reliable good initial quantum efficiency and in-situ laser cleaning for the copper cathodes in the RF gun

    NASA Astrophysics Data System (ADS)

    Zhou, F.; Sheppard, J. C.; Vecchione, T.; Jongewaard, E.; Brachmann, A.; Corbett, J.; Gilevich, S.; Weathersby, S.

    2015-05-01

    Establishing good initial quantum efficiency (QE) and reliable in-situ cleaning for copper cathode in the RF gun is of critical importance for the RF gun operations. Recent studies on the SLAC RF gun test bed indicated that the pre-cleaning (plasma cleaning) in the test chamber followed by copper cathode exposure to air for cathode change leads to a very low initial QE in the RF gun, and also demonstrated that without the pre-cleaning good initial QE >4×10-5 can be routinely achieved in the RF gun with the cathodes of QE <1×10-7 measured in the test chamber. QE can decay over the time in the RF gun. The in-situ laser cleaning technique for copper cathodes in the RF gun is established and refined in comparison to previous cleaning at the linac coherent light source, resulting in an improved QE and emittance evolutions. The physics of the laser cleaning process is discussed. It is believed that the reflectivity change is one of the major factors for the QE boost with the laser cleaning.

  5. Diffusion of silver over atomically clean silicon surfaces

    SciTech Connect

    Dolbak, A. E. Ol'shanetskii, B. Z.

    2013-06-15

    The diffusion of silver the (111), (100), and (110) silicon surfaces is studied by Auger electron spectroscopy and low-energy electron diffraction. The mechanisms of diffusion over the (111) and (110) surfaces are revealed, and the temperature dependences of diffusion coefficients are measured. An anisotropy of silver diffusion over the (110) surface is detected.

  6. Surface oxidation of GaN(0001): Nitrogen plasma-assisted cleaning for ultrahigh vacuum applications

    SciTech Connect

    Gangopadhyay, Subhashis; Schmidt, Thomas Kruse, Carsten; Figge, Stephan; Hommel, Detlef; Falta, Jens

    2014-09-01

    The cleaning of metal-organic vapor-phase epitaxial GaN(0001) template layers grown on sapphire has been investigated. Different procedures, performed under ultrahigh vacuum conditions, including degassing and exposure to active nitrogen from a radio frequency nitrogen plasma source have been compared. For this purpose, x-ray photoelectron spectroscopy, reflection high-energy electron diffraction, and scanning tunneling microscopy have been employed in order to assess chemical as well as structural and morphological surface properties. Initial degassing at 600 °C under ultrahigh vacuum conditions only partially eliminates the surface contaminants. In contrast to plasma assisted nitrogen cleaning at temperatures as low as 300 °C, active-nitrogen exposure at temperatures as high as 700 °C removes the majority of oxide species from the surface. However, extended high-temperature active-nitrogen cleaning leads to severe surface roughening. Optimum results regarding both the removal of surface oxides as well as the surface structural and morphological quality have been achieved for a combination of initial low-temperature plasma-assisted cleaning, followed by a rapid nitrogen plasma-assisted cleaning at high temperature.

  7. Chrome and Zinc Contaminants Removal from Silicon (100) Surfaces by Remote Plasma Cleaning Techniques

    NASA Astrophysics Data System (ADS)

    Lee, Seungwook; Lee, Jaegab; Lee, Chongmu

    2001-06-01

    Removal of Cr and Zn impurities on Si surfaces using remote plasma H2 was investigated. Si surfaces were contaminated intentionally with low-purity acetone. To determine the optimum process conditions, remote plasma H2 cleaning was conducted for various rf powers and plasma exposure times. After remote plasma H2 cleaning, Si surfaces were analyzed by total X-ray reflection fluorescence (TXRF), surface photovoltage (SPV) and atomic force microscopy (AFM). The concentrations of Cr and Zn impurities were reduced by more than a factor of 2 and the minority carrier lifetime increased. Also the root-mean-square (RMS) roughness decreased by more than 30% after the remote plasma H2 cleaning. TXRF analysis results show that remote plasma H2 cleaning is effective in eliminating Cr and Zn impurities from the Si surface only if it is performed under optimum process conditions. AFM analysis results also show that remote plasma H2 cleaning causes no damage to the Si surface. Cr and Zn impurities on the Si substrate are considered to be contaminated as forms of hydroxides, silioxides and oxides on chemical oxides formed during intentional chemical contamination. The removal mechanism of Cr and Zn impurities using remote plasma H2 treatments is proposed for the lift-off during the removal of underlying chemical oxides.

  8. Surface Analysis Evaluation of Handwipe Cleaning for the Space Shuttle RSRM

    NASA Technical Reports Server (NTRS)

    Lesley, Michael W.; Anderson, Erin L.; McCool, Alex (Technical Monitor)

    2001-01-01

    In this paper we discuss the role of surface-sensitive spectroscopy (electron spectroscopy for chemical analysis, or ESCA) in the selection of solvents to replace 1,1,1-trichloroethane in handwipe cleaning of bonding surfaces on NASA's Space Shuttle Reusable Solid Rocket Motor (RSRM). Removal of common process soils from a wide variety of metallic and polymeric substrates was characterized. The cleaning efficiency was usually more dependent on the type of substrate being cleaned and the specific process soil than on the solvent used. A few substrates that are microscopically rough or porous proved to be difficult to clean with any cleaner, and some soils were very tenacious and difficult to remove from any substrate below detection limits. Overall, the work showed that a wide variety of solvents will perform at least as well as 1,1,1-trichloroethane.

  9. Laser surface modification of metallic biomaterials

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, Amit; Balla, Vamsi Krishna; Roy, Mangal; Bose, Susmita

    2011-06-01

    Load-bearing metal implants often fail prematurely due to inadequate biocompatibility, mechanical/tribological properties, and poor osseointegration. It is well known that biomaterials' surface plays a vital role in the response to these metal implants in the biological environment. The biological effectiveness of artificial implants is determined mainly by their surface characteristics such as surface morphology, microstructure, composition, mechanical properties, wettabilility, and surface free energy. Hence, there is significant interest toward surface modification and effective design of load-bearing metal implants so as to improve their surface properties and thereby elicit a specific, desired, and timely response from the surrounding cells and tissues. In this article, we provide an insight into laser surface modification of Ti/Ti6Al4V alloy with or without functional gradation in composition and their microstructural, in vitro wear and biological properties for various loadbearing orthopedic applications.

  10. Self-Cleaning Surfaces Prepared By Microstructuring System

    NASA Astrophysics Data System (ADS)

    Sabbah, Abbas; Vandeparre, H.; Brau, F.; Damman, P.

    The wettability of materials is a very important aspect of surface science governed by the chemical composition of the surface and its morphology. In this context, materials replicating nature's superhydrophobic surfaces, such as lotus leafs, rose petals and butterfly wings, have widely attracted attention of physicists and material engineers [1-3]. Despite of considerable efforts during the last decade, superhydrophobic surfaces are still expensive and usually involved microfabrication processes, such as photolithography technique. In this study, we propose an original and simple method to create superhydrophobic surfaces by controling elastic instabilities [4-8]. Indeed, we demonstrate that the self-organization of wrinkles on top of non-wettable polymer surfaces leads to surperhydrophobic surfaces.

  11. Preliminary Results of the Er:YAG Laser Cleaning of Mural Paintings

    NASA Astrophysics Data System (ADS)

    Andreotti, A.; Colombini, M. P.; Felici, A.; deCruz, A.; Lanterna, G.; Lanfranchi, M.; Nakahara, K.; Penaglia, F.

    The conservation of mural paintings requires a deep knowledge of the alterations caused by natural ageing, environmental agents and previous restoration treatments. All the operations concerning cleaning and consolidation of wall paintings must assure the safety of the paint layers. This is especially true the more fragile the painting technique. For example, "a secco" paintings, executed with organic binders such as tempera, oil, glue, when altered and damaged, present a very weak adhesion to the mortar underneath, and provoke detachment of paint fragments. In this circumstance it is necessary to find a feasible alternative to the usual cleaning methods (wet and mechanical ones) and a valid way to operate. Moreover, the removal of scialbo layers (a thick, pure lime layer applied on the wall painting) presents difficulties in order to preserve the integrity of the painting layers. Previous experiments carried out in Opificio with Er:YAG laser on easel painting cleaning, lead us to extend the experiments on the cleaning of mural paintings.

  12. Laser neutralization of surface and buried munitions

    NASA Astrophysics Data System (ADS)

    Habersat, James D.; Schilling, Bradley W.; Alexander, Joe; Lehecka, Thomas

    2012-06-01

    In recent years NVESD has been investigating laser-based neutralization of buried mines and minelike targets. This paper covers the most recent efforts in this area. A field-test was conducted to demonstrate the state-of-the-art capability for standoff laser neutralization of surface and buried mines. The neutralization laser is a Ytterbium fiber laser with a nominal power output of 10 kW and a beam quality of M2 ~ 1.8 at maximum power. Test trials were conducted at a standoff range of 50 meters with a 20° angle of attack. The laser was focused to a submillimeter spot using a Cassegrain telescope with a 12.5 inch diameter primary mirror. The targets were 105 mm artillery rounds with a composition B explosive fill. Three types of overburden were studied: sand, soil, and gravel. Laser neutralization capability was demonstrated under these conditions for live rounds buried under 7 cm of dry sand, 4 cm of soil, and 2 cm of gravel.

  13. Adhesion of metals to a clean iron surface studied with LEED and Auger emission spectroscopy.

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1972-01-01

    Discussion of the results of adhesion experiments conducted with various metals contacting a clean iron surface. The metals included gold, silver, nickel, platinum, lead, tantalum, aluminum, and cobalt. Some of the metals were examined with oxygen present on their surface as well as in the clean state. The results indicate that, with the various metals contacting iron, the cohesively weaker will adhere and transfer to the cohesively stronger. The chemical activity of the metal also influenced the adhesive forces measured. With oxygen present on the metal surface, the adhesive forces measured could be correlated with the binding energy of the metal to oxygen.

  14. Quantum Efficiency and Topography of Heated and Plasma-Cleaned Copper Photocathode Surfaces

    SciTech Connect

    Palmer, Dennis T.; Kirby, R.E.; King, F.K.; /SLAC

    2005-08-04

    We present measurements of photoemission quantum efficiency (QE) for copper photocathodes heated and cleaned by low energy argon and hydrogen ion plasma. The QE and surface roughness parameters were measured before and after processing and surface chemical composition was tracked in-situ with x-ray photoelectron spectroscopy (XPS). Thermal annealing at 230 C was sufficient to improve the QE by 3-4 orders of magnitude, depending on the initial QE. Exposure to residual gas slowly reduced the QE but it was easily restored by argon ion cleaning for a few minutes. XPS showed that the annealing or ion bombardment removed surface water and hydrocarbons.

  15. Spatial uniformity in chamber-cleaning plasmas measured using planar laser-induced fluorescence

    SciTech Connect

    Steffens, Kristen L.; Sobolewski, Mark A.

    1998-11-24

    Planar laser-induced fluorescence (PLIF) measurements were made to determine 2-D spatial maps of CF{sub 2} density as an indicator of chemical uniformity in 92%CF{sub 4}/O{sub 2} and 50%C{sub 2}F{sub 6}/O{sub 2} chamber-cleaning plasmas. Measurements were also made of broadband optical emission and of discharge current and voltage. All measurements were made in the Gaseous Electronics Conference (GEC) reference cell, a capacitively-coupled, parallel-plate platform designed to facilitate comparison of results among laboratories. The PLIF and emission results were found to correlate with discharge current and voltage measurements. Together, these optical and electrical measurements provide insight into the optimization of chamber-cleaning processes and reactors and suggest new methods of monitoring plasma uniformity.

  16. Control of pyrite surface chemistry in physical coal cleaning

    SciTech Connect

    Luttrell, G.H.; Yoon, R.H.; Zachwieja, J.; Lagno, M.

    1992-06-24

    To better understand the surface chemical properties of coal and mineral pyrite, studies on the effect of flotation surfactants (frother and kerosene) on the degree of hydrophobicity have been conducted. The presence of either frother or kerosene enhanced the flotability of coal and mineral pyrite with a corresponding decrease in induction time over the pH range examined. Scanning electron microscopy (SEM) results indicate a correlation exists between the sample surface morphology and crystal structure and the observed hydrophobicity. As a result of the data obtained from the surface characterization studies, controlled surface oxidation was investigated as a possible pyrite rejection scheme in microbubble column flotation.

  17. The construction, fouling and enzymatic cleaning of a textile dye surface.

    PubMed

    Onaizi, Sagheer A; He, Lizhong; Middelberg, Anton P J

    2010-11-01

    The enzymatic cleaning of a rubisco protein stain bound onto Surface Plasmon Resonance (SPR) biosensor chips having a dye-bound upper layer is investigated. This novel method allowed, for the first time, a detailed kinetic study of rubisco cleanability (defined as fraction of adsorbed protein removed from a surface) from dyed surfaces (mimicking fabrics) at different enzyme concentrations. Analysis of kinetic data using an established mathematical model able to decouple enzyme transfer and reaction processes [Onaizi, He, Middelberg, Chem. Eng. Sci. 64 (2008) 3868] revealed a striking effect of dyeing on enzymatic cleaning performance. Specifically, the absolute rate constants for enzyme transfer to and from a dye-bound rubisco stain were significantly higher than reported previously for un-dyed surfaces. These increased transfer rates resulted in higher surface cleanability. Higher enzyme mobility (i.e., higher enzyme adsorption and desorption rates) at the liquid-dye interface was observed, consistent with previous suggestions that enzyme surface mobility is likely correlated with overall enzyme cleaning performance. Our results show that reaction engineering models of enzymatic action at surfaces may provide insight able to guide the design of better stain-resistant surfaces, and may also guide efforts to improve cleaning formulations. PMID:20708195

  18. ANNUAL REPORT. ATMOSPHERIC-PRESSURE PLASMA CLEANING OF CONTAMINATED SURFACES

    EPA Science Inventory

    The objective of this work is to demonstrate a practical, atmospheric pressure plasma tool for the surface decontamination of nuclear waste. Decontamination of radioactive materials that have accumulated on the surfaces of equipment and structures is a challenging and costly unde...

  19. Control of pyrite surface chemistry in physical coal cleaning

    SciTech Connect

    Luttrell, G.H.; Yoon, R.H.; Zachwieja, J.B.; Lagno, M.L.

    1992-06-24

    Correlation of the hydrophobicity measurements of coal and mineral pyrite with changes in the surface composition of the samples as determined by x-ray photoelectron spectroscopy (XPS) reveals that similar surface oxidation products are found on both mineral and coal pyrite samples. The surface oxidation layer of these samples is comprised of different amounts of hydrophilic species (iron hydroxy-oxides and/or iron oxides) and hydrophobic species (polysulfide or elemental sulfur). The resulting hydrophobicity of these samples may be attributed to the ratio of hydrophilic (surface oxides) to hydrophobic (sulfur-containing) species in the surface oxidation layer. Also, coal pyrite samples were found to exhibit a greater degree of superficial oxidation and a less hydrophobic character as compared to the mineral pyrite samples.

  20. Oxalic acid adsorption states on the clean Cu(110) surface

    NASA Astrophysics Data System (ADS)

    Fortuna, Sara

    2016-11-01

    Carboxylic acids are known to assume a variety of configurations on metallic surfaces. In particular oxalic acid on the Cu(110) surface has been proposed to assume a number of upright configurations. Here we explore with DFT calculations the possible structures that oxalic acid can form on copper 110 at different protonation states, with particular attention at the possibility of forming structures composed of vertically standing molecules. In its fully protonated form it is capable of anchoring itself on the surface thanks to one of its hydrogen-free oxygens. We show the monodeprotonated upright molecule with two oxygens anchoring it on the surface to be the lowest energy conformation of a single oxalic molecules on the Cu(110) surface. We further show that it is possible for this configuration to form dense hexagonally arranged patterns in the unlikely scenario in which adatoms are not involved.

  1. New method of space debris cleaning based on light negative force: tractor laser

    NASA Astrophysics Data System (ADS)

    Sun, Qiongge; Gao, Long; Li, Chen

    2016-01-01

    This paper presents a new way of space debris removal and protection, that is, using tractor laser, which based on light negative force, to achieve space debris cleaning and shielded. Tractor laser is traceable from the theory of optical tweezers, accompanied with non-diffraction beam. These kind of optical beams have the force named negative force pointing to optical source, this will bring the object along the trajectory of laser beam moving to the optical source. The negative force leads to the new method to convey and sampling the space micro-objects. In this paper, the application of tractor laser in the space debris collection and protection of 1cm is studied. The application of the several tractor beams in the space debris and sample collection is discussed. The proposed method can reduce the requirements of the laser to the satellite platform, and realize the collection of space debris, make the establishment of the space garbage station possible, and help to study the spatial non contact sample transmission and reduce the risk of space missions.

  2. The impact of different cleaning processes on the laser damage threshold of antireflection coatings for Z-Backlighter optics at Sandia National Laboratories

    NASA Astrophysics Data System (ADS)

    Field, Ella; Bellum, John; Kletecka, Damon

    2014-09-01

    The Z-Backlighter lasers at Sandia National Laboratories are kilojoule class, pulsed systems operating with ns pulse lengths at 527 nm and ns and sub-ps pulse lengths at 1054 nm (www.z-beamlet.sandia.gov), and are linked to the most powerful and energetic x-ray source in the world, the Z-Accelerator (http://www.sandia.gov/z-machine/). An important Z-Backlighter optic is a flat, fused silica optic measuring 32.5 cm × 32.5 cm × 1 cm with an antireflection (AR) coating on both sides. It is used as a debris shield to protect other Z-Backlighter laser optics from high-velocity particles released by the experiments conducted in the Z-Accelerator. Each experiment conducted in the Z-Accelerator releases enough debris to cloud the surface of a debris shield, which means that a debris shield cannot be used for more than one experiment. Every year, the large optics coating facility [1] at Sandia provides AR coatings for approximately 50 debris shields, in addition to AR coatings for numerous other meter-class Z-Backlighter lenses and windows. As with all Z-Backlighter optical coatings, these AR coatings must have a high laser-induced damage threshold (LIDT) in order to withstand the powerful Z-Backlighter laser fluences. Achieving a good LIDT depends not only on the coating deposition processes but also on the polishing and cleaning processes used to prepare the coated and uncoated surfaces [2]. We spend a lot of time, both before and after the coatings have been deposited, manually cleaning the optics, including the debris shields, even though they are an expendable type of optic. Therefore, in this study we have tested new cleaning methods in addition to our current method to determine their impact on the LIDT of AR coatings, and conclude whether a shorter-duration or less labor-intensive cleaning process would suffice.

  3. In vitro studies on the effect of cleaning methods on different implant surfaces.

    PubMed

    Augthun, M; Tinschert, J; Huber, A

    1998-08-01

    The effect of specific cleaning procedures was examined on the surfaces of 3 implant types with different coatings and shapes (plasma sprayed [PS]; hydroxyapatite coated [HA] implants; and smooth titanium surface screws) using a scanning electron microscope. Each implant was treated for 60 seconds per instrument with one of 6 different hygiene measures: plastic curet, metal curet, diamond polishing device, ultrasonic scaler, air-powder-water spray with sodium hydrocarbonate solution, and chlorhexidine 0.1% solution rinse. The air-powder-abrasive system, chlorhexidine rinse, and curettage with a plastic instrument caused little or no surface damage in all but the hydroxyapatite-coated fixtures. Therefore, these 3 methods were tested to determine their cleaning efficacy in a second clinical study, which did not include the HA-coated fixture. Two implants were placed on the facial aspects of both upper molar regions using individual acrylic plates. Thus, 2 fixtures on each side were examined in each patient. The examination revealed that only the sodium hydrocarbonate spray yielded a clean fixture without damage to the implant surface. In a third stage, which imitated the clinical procedure of the second approach, the cell growth of mouse-fibroblasts on implant surfaces was examined after cleaning the surface with plastic scaler and the air-abrasive system, which represents the least damaging and most effective methods. In contrast to the implant surfaces treated with plastic scalers, mostly vital cells were found on implants sprayed with the air-abrasive system. PMID:9736367

  4. Self-cleaning skin-like prosthetic polymer surfaces

    SciTech Connect

    Simpson, John T.; Ivanov, Ilia N.; Shibata, Jason

    2012-03-27

    An external covering and method of making an external covering for hiding the internal endoskeleton of a mechanical (e.g., prosthetic) device that exhibits skin-like qualities is provided. The external covering generally comprises an internal bulk layer in contact with the endoskeleton of the prosthetic device and an external skin layer disposed about the internal bulk layer. The external skin layer is comprised of a polymer composite with carbon nanotubes embedded therein. The outer surface of the skin layer has multiple cone-shaped projections that provide the external skin layer with superhydrophobicity. The carbon nanotubes are preferably vertically aligned between the inner surface and outer surface of the external skin layer in order to provide the skin layer with the ability to transmit heat. Superhydrophobic powders may optionally be used as part of the polymer composite or applied as a coating to the surface of the skin layer to enhance superhydrophobicity.

  5. Surface Microbes in the Neonatal Intensive Care Unit: Changes with Routine Cleaning and over Time

    PubMed Central

    Bokulich, Nicholas A.; Mills, David A.

    2013-01-01

    Premature infants in neonatal intensive care units (NICUs) are highly susceptible to infection due to the immaturity of their immune systems, and nosocomial infections are a significant risk factor for death and poor neurodevelopmental outcome in this population. To investigate the impact of cleaning within a NICU, a high-throughput short-amplicon-sequencing approach was used to profile bacterial and fungal surface communities before and after cleaning. Intensive cleaning of surfaces in contact with neonates decreased the total bacterial load and the percentage of Streptococcus species with similar trends for total fungal load and Staphylococcus species; this may have clinical relevance since staphylococci and streptococci are the most common causes of nosocomial NICU infections. Surfaces generally had low levels of other taxa containing species that commonly cause nosocomial infections (e.g., Enterobacteriaceae) that were not significantly altered with cleaning. Several opportunistic yeasts were detected in the NICU environment, demonstrating that these NICU surfaces represent a potential vector for spreading fungal pathogens. These results underline the importance of routine cleaning as a means of managing the microbial ecosystem of NICUs and of future opportunities to minimize exposures of vulnerable neonates to potential pathogens and to use amplicon-sequencing tools for microbial surveillance and hygienic testing in hospital environments. PMID:23740726

  6. Surface microbes in the neonatal intensive care unit: changes with routine cleaning and over time.

    PubMed

    Bokulich, Nicholas A; Mills, David A; Underwood, Mark A

    2013-08-01

    Premature infants in neonatal intensive care units (NICUs) are highly susceptible to infection due to the immaturity of their immune systems, and nosocomial infections are a significant risk factor for death and poor neurodevelopmental outcome in this population. To investigate the impact of cleaning within a NICU, a high-throughput short-amplicon-sequencing approach was used to profile bacterial and fungal surface communities before and after cleaning. Intensive cleaning of surfaces in contact with neonates decreased the total bacterial load and the percentage of Streptococcus species with similar trends for total fungal load and Staphylococcus species; this may have clinical relevance since staphylococci and streptococci are the most common causes of nosocomial NICU infections. Surfaces generally had low levels of other taxa containing species that commonly cause nosocomial infections (e.g., Enterobacteriaceae) that were not significantly altered with cleaning. Several opportunistic yeasts were detected in the NICU environment, demonstrating that these NICU surfaces represent a potential vector for spreading fungal pathogens. These results underline the importance of routine cleaning as a means of managing the microbial ecosystem of NICUs and of future opportunities to minimize exposures of vulnerable neonates to potential pathogens and to use amplicon-sequencing tools for microbial surveillance and hygienic testing in hospital environments. PMID:23740726

  7. Fluid drag reduction and efficient self-cleaning with rice leaf and butterfly wing bioinspired surfaces.

    PubMed

    Bixler, Gregory D; Bhushan, Bharat

    2013-09-01

    Researchers are continually inspired by living nature to solve complex challenges. For example, unique surface characteristics of rice leaves and butterfly wings combine the shark skin (anisotropic flow leading to low drag) and lotus leaf (superhydrophobic and self-cleaning) effects, producing the so-called rice and butterfly wing effect. In this paper, we present an overview of rice leaf and butterfly wing fluid drag and self-cleaning studies. In addition, we examine two other promising aquatic surfaces in nature known for such properties, including fish scales and shark skin. Morphology, drag, self-cleaning, contact angle, and contact angle hysteresis data are presented to understand the role of wettability, viscosity, and velocity. Liquid repellent coatings are utilized to recreate or combine various effects. Discussion is provided along with conceptual models describing the role of surface structures related to low drag, self-cleaning, and antifouling properties. Modeling provides design guidance when developing novel low drag and self-cleaning surfaces for applications in the medical, marine, and industrial fields. PMID:23884183

  8. Spectrally and temporally resolved laser emission from vertical cavity surface emitting lasers

    SciTech Connect

    Sinclair, M.; Gourley, P.L.; Brennan, T.M.; Hammons, B.E.

    1992-12-31

    We have measured the laser emission spectra of several vertical cavity surface emitting lasers following pulsed laser excitation, with a time resolution of < 1 ps. Correlations between the observed pulse widths and cavity lifetimes were observed.

  9. Surface modification of titanium membrane by chemical vapor deposition and its electrochemical self-cleaning

    NASA Astrophysics Data System (ADS)

    Li, X. W.; Li, J. X.; Gao, C. Y.; Chang, M.

    2011-10-01

    Membrane separation is applied widely in many fields, while concentration polarization and membrane fouling, limiting its promotion and application greatly, are the bottlenecks in membrane application. Among which, membrane fouling is irreversible, membrane must be periodically cleaned or even replaced to restore permeability. Membrane cleaning has become one of the key issues in membrane separation areas. Considering incomparable electrochemical advantages of boron-doped diamond (BDD) film electrode over conventional electrode, a new composite membrane Ti/BDD, made by depositing CVD (chemical vapor deposition) boron-doped diamond film on titanium(Ti) membrane to modify porous titanium surface, that can be cleaned electrochemically is proposed. Feasibility of its preparation and application is discussed in this paper. Results shows that based on the unique electrochemical properties of diamond, cleaning level of this composite Ti/BDD membrane is significantly increased, making membrane life and efficiency improved prominently.

  10. Femtosecond laser controlled wettability of solid surfaces.

    PubMed

    Yong, Jiale; Chen, Feng; Yang, Qing; Hou, Xun

    2015-12-14

    Femtosecond laser microfabrication is emerging as a hot tool for controlling the wettability of solid surfaces. This paper introduces four typical aspects of femtosecond laser induced special wettability: superhydrophobicity, underwater superoleophobicity, anisotropic wettability, and smart wettability. The static properties are characterized by the contact angle measurement, while the dynamic features are investigated by the sliding behavior of a liquid droplet. Using different materials and machining methods results in different rough microstructures, patterns, and even chemistry on the solid substrates. So, various beautiful wettabilities can be realized because wettability is mainly dependent on the surface topography and chemical composition. The distinctions of the underlying formation mechanism of these wettabilities are also described in detail. PMID:26415826