Multipulse passively Q-switched Nd:YAG laser for material surface cleaning

2002 ◽  
Author(s):  
Constantin G. Fenic ◽  
Aurel Stratan ◽  
Razvan V. Dabu ◽  
Ion N. Mihailescu ◽  
Constantin Blanaru ◽  
...  
Keyword(s):  
Nd:Yag Laser ◽  
Surface Cleaning ◽  
Material Surface

Preliminary studies of material surface cleaning with a multi-pulse passively Q-switched Nd:YAG laser

2004 ◽  
Vol 36 (2) ◽  
pp. 125-130 ◽  
Author(s):  
Constantin Fenic ◽  
Razvan Dabu ◽  
Aurel Stratan ◽  
Constantin Blanaru ◽  
Constantin Ungureanu ◽  
...  
Keyword(s):  
Nd:Yag Laser ◽  
Surface Cleaning ◽  
Material Surface

scholarly journals Effects of the impact of a low temperature nitrogen jet on metallic surfaces

2012 ◽  
Vol 468 (2147) ◽  
pp. 3601-3619 ◽  
Author(s):  
H. Laribou ◽  
C. Fressengeas ◽  
D. Entemeyer ◽  
V. Jeanclaude ◽  
R. Pesci ◽  
...  
Keyword(s):  
Low Temperature ◽  
Surface Cleaning ◽  
Ductile Deformation ◽  
Material Surface ◽  
Metallic Surfaces ◽  
Test Parameters ◽  
Upstream Pressure ◽  
Grain Fragmentation ◽  
Transformation Mechanisms ◽  
The Impact

The technology of nitrogen jets impacting surfaces at low temperature has recently been introduced for surface cleaning/stripping. Under the impact of the jet, the material surface undergoes a thermomechanical shock inducing complex transformation mechanisms. Depending on the material and test parameters such as standoff distance, dwell time, upstream pressure, the latter include cleavage, cracking, spalling, blistering, grain fragmentation, phase transformation and ductile deformation. Quite often, these modes are superimposed in the same test, or even in the same material area. In this study, an overview of these mechanisms is proposed for metallic materials. Measurements of thermomechanical variables in the impacted area are presented and the influence of the test parameters on surface transformation is investigated. Grain fragmentation and ultrafast transport of nitrogen in a deep layer below the surface are explored.

Plasma Jet Coupled with Nd:YAG Laser: New Approach to Surface Cleaning

2007 ◽  
Vol 4 (S1) ◽  
pp. S33-S38 ◽  
Author(s):  
Nils Mainusch ◽  
Christina Pflugfelder ◽  
Jürgen Ihlemann ◽  
Wolfgang Viöl
Keyword(s):  
Nd:Yag Laser ◽  
Plasma Jet ◽  
Surface Cleaning ◽  
New Approach

Inactivation of foodborne pathogens on food packaging and in cow milk by exposure to a Nd:YAG laser

2017 ◽  
Vol 95 (7) ◽  
pp. 662-669 ◽  
Author(s):  
N. Yasmin ◽  
S. Hameed ◽  
R. Javed ◽  
S. Ahmed ◽  
M. Imran
Keyword(s):  
Foodborne Pathogens ◽  
Nd:Yag Laser ◽  
Food Packaging ◽  
Pathogenic Bacteria ◽  
Raw Milk ◽  
Cow Milk ◽  
Material Surface ◽  
Laser Exposure ◽  
Agar Surface ◽  
Industrial Level

This study demonstrates the inhibition of selective foodborne pathogenic bacteria by exposure to a 355 and 266 nm Nd:YAG laser. In baseline assay P. aeruginosa showed maximum inhibition followed by Escherichia coli, Staphylococcus aureus, Salmonella typhimurium, and Listeria monocytogenes grown on agar surface. Cell lysis was confirmed by confocal microscopy for all pathogens. In liquid media, P. aeruginosa was irradiated with the third harmonic of a Nd:YAG laser pulse energy of 185 mJ, which was able to reduce the population of 1.65 × 105 by 4.7 logs, while P. aeruginosa could only be reduced by 0.73 log/cm2 on packaging material surface. In the final phase, the laser’s potential was preliminarily tested for sterilization of raw cow milk. The reduction patterns of E. coli, Salmonella sp. yeasts and Lactobacillus sp. were 30%, 25%, 47%, and 30%, respectively, in raw milk, moreover, laser exposure had no significant impact on physio-chemistry of milk. Therefore, results indicate the potential application of laser in packing materials and milk sterilization at the industrial level.

Suppression of γ’ Precipitation in a Laser-Melted Nickel-Base Alloy

1977 ◽  
Vol 35 ◽  
pp. 270-271
Author(s):  
J. M. Walsh ◽  
J. C. Whittles ◽  
B. H. Kear ◽  
E. M. Breinan
Keyword(s):  
Cooling Rate ◽  
Base Alloy ◽  
Material Surface ◽  
Intimate Contact ◽  
Absorbed Power ◽  
Perfect Contact ◽  
Nickel Base ◽  
Rapidly Solidified ◽  
Limiting Case ◽  
The Heat Transfer Coefficient

Conventionally cast γ’ precipitation hardened nickel-base superalloys possess well-defined dendritic structures and normally exhibit pronounced segregation. Splat quenched, or rapidly solidified alloys, on the other hand, show little or no evidence for phase decomposition and markedly reduced segregation. In what follows, it is shown that comparable results have been obtained in superalloys processed by the LASERGLAZE™ method.In laser glazing, a sharply focused laser beam is traversed across the material surface at a rate that induces surface localized melting, while avoiding significant surface vaporization. Under these conditions, computations of the average cooling rate can be made with confidence, since intimate contact between the melt and the self-substrate ensures that the heat transfer coefficient is reproducibly constant (h=∞ for perfect contact) in contrast to the variable h characteristic of splat quenching. Results of such computations for pure nickel are presented in Fig. 1, which shows that there is a maximum cooling rate for a given absorbed power density, corresponding to the limiting case in which melt depth approaches zero.

TEM characterization of silicon epitaxial layer grown on Si-TaS2, eutectic composites

1991 ◽  
Vol 49 ◽  
pp. 802-803
Author(s):  
C.M. Sung ◽  
M. Levinson ◽  
M. Tabasky ◽  
K. Ostreicher ◽  
B.M. Ditchek
Keyword(s):  
Substrate Surface ◽  
Bulk Sample ◽  
Surface Cleaning ◽  
Native Oxide ◽  
Czochralski Growth ◽  
Ion Milling ◽  
Cross Sectional ◽  
Cleaning Methods ◽  
Field Emission Cathodes

Directionally solidified Si/TaSi2 eutectic composites for the development of electronic devices (e.g. photodiodes and field-emission cathodes) were made using a Czochralski growth technique. High quality epitaxial growth of silicon on the eutectic composite substrates requires a clean silicon substrate surface prior to the growth process. Hence a preepitaxial surface cleaning step is highly desirable. The purpose of this paper is to investigate the effect of surface cleaning methods on the epilayer/substrate interface and the characterization of silicon epilayers grown on Si/TaSi2 substrates by TEM.Wafers were cut normal to the <111> growth axis of the silicon matrix from an approximately 1 cm diameter Si/TaSi2 composite boule. Four pre-treatments were employed to remove native oxide and other contaminants: 1) No treatment, 2) HF only; 3) HC1 only; and 4) both HF and HCl. The cross-sectional specimens for TEM study were prepared by cutting the bulk sample into sheets perpendicular to the TaSi2 fiber axes. The material was then prepared in the usual manner to produce samples having a thickness of 10μm. The final step was ion milling in Ar+ until breakthrough occurred. The TEM samples were then analyzed at 120 keV using the Philips EM400T.

Microstructures of Laser Processed Fe-Cr Surface Alloys

1981 ◽  
Vol 39 ◽  
pp. 328-329
Author(s):  
P. A. Molian ◽  
K. H. Khan ◽  
W. E. Wood
Keyword(s):  
Cooling Rate ◽  
Pure Iron ◽  
Continuous Wave ◽  
Laser Surface ◽  
Material Surface ◽  
Constitution Diagram ◽  
Incident Power ◽  
Surface Alloying ◽  
Laser Surface Alloying ◽  
Spot Diameter

In recent years, the effects of chromium on the transformation characteristics of pure iron and the structures produced thereby have been extensively studied as a function of cooling rate. In this paper, we present TEM observations made on specimens of Fe-10% Cr and Fe-20% Cr alloys produced through laser surface alloying process with an estimated cooling rate of 8.8 x 104°C/sec. These two chromium levels were selected in order to study their phase transformation characteristics which are dissimilar in the two cases as predicted by the constitution diagram. Pure iron (C<0.01%, Si<0.01%, Mn<0.01%, S=0.003%, P=0.008%) was electrodeposited with chromium to the thicknesses of 40 and 70μm and then vacuum degassed at 400°F to remove the hydrogen formed during electroplating. Laser surface alloying of chromium into the iron substrate was then performed employing a continuous wave CO2 laser operated at an incident power of 1200 watts. The laser beam, defocussed to a spot diameter of 0.25mm, scanned the material surface at a rate of 30mm/sec, (70 ipm).

Bipolar radiofrequency induced thermotherapy and 1064 nm Nd:Yag laser in endovenous occlusion of insufficient veins: short term follow up results

VASA ◽  
2011 ◽  
Vol 40 (3) ◽  
pp. 235-240 ◽  
Author(s):  
Krnic ◽  
Sucic
Keyword(s):  
Side Effects ◽  
Success Rate ◽  
Nd:Yag Laser ◽  
Main Stem ◽  
Short Term ◽  
Main Trunk ◽  
Bipolar Radiofrequency ◽  
Saphenous Veins ◽  
Skin Redness ◽  
Complete Failure

Background: The aim of this study is to report our results in main stem vein closure using the bipolar radiofrequency induced thermotherapy (RFITT) system and the 1064nm Nd:Yag laser. Patients and methods: 44 incompetent main stem veins (37 great saphenous veins, one lesser saphenous vein, and 6 anterior accessory saphenous veins) in 29 patients were treated using RFITT. 53 incompetent main stem veins (45 great saphenous veins, 4 lesser saphenous veins, and 4 anterior accessory saphenous veins) in 43 patients were treated endovenously with 1064 nm Nd:Yag laser. All patients underwent postoperative duplex scanning within a month after procedure, as well as a short interview regarding postoperative discomfort. Results: In main stem veins treated with RFITT, the success rate within the first month was 86,4 % (38 out of 44 veins). Complete failure rate was 13,6 % (6 out of 44 veins). In 53 main stem veins treated by 1064 nm Nd:Yag laser, the success rate was 100 %, consisting of 98,1 % complete success (52/53 veins), and 1,9 % partial success (1/53 veins). None of the patients treated with RFITT experienced postoperative adverse effects, whereas 13/43 (30,2 %) patients treated with laser had to use oral analgesics after the treatment, and 21/43 (48,8 %) patients reported transient skin changes, such as bruising or skin redness. Conclusions: RFITT system was fairly efficient in the short term for closure of main trunk veins, whereas longer term results are still scarce. Postoperative side effects of RFITT were minimal. 1064nm Nd:Yag laser, according to short term results, proved to be very effective for main stem vein closure. Postoperative side effects related to 1064 nm Nd:Yag endovenous laser treatment proved to be minor, transient, and acceptable.

Das Management von Glaskörpertrübungen

2020 ◽  
Vol 10 (03) ◽  
pp. 243-254
Author(s):  
Albrecht Lommatzsch
Keyword(s):  
Nd:Yag Laser ◽  
Randomisierte Studien

ZusammenfassungDas Management von symptomatischen Glaskörpertrübungen stellt sich in der täglichen Praxis oft als kompliziert dar. Die Nd:YAG-Laser-Vitreolyse rückt als weitere therapeutische Option immer mehr in den Fokus. Vergleichende randomisierte Studien zur Vitrektomie, Nd:YAG-Laser-Vitreolyse und einer abwartenden Vorgehensweise zum Spontanverlauf gibt es leider nicht. Dieser Beitrag versucht, zu dieser Problematik einen Überblick zu geben.

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