Papers by Keyword: Nd:YAG Laser

Abstract: Steel alloys made of sheet metal are important materials because of their high strength applications in construction, automobiles, ships, aircraft, and military products. Among the best and fastest non-traditional ways to cut sheet metal these days is laser cutting. Therefore, it's important to comprehend how the parameters of LC affect the quality of the cut. A thorough analysis was provided to find out which LC parameters have the greatest impact on cutting quality as well as how they affect the kerf quality and cut surface. An overview of the benefits of LC over other machining techniques was provided. Furthermore, an explanation of the various laser sources and the laser cutting technique were given. by eliminating each source's spectrum of cut material thicknesses and their benefits. Graphs and formulae provided a detailed illustration of the cutting performance characteristics. Tables and graphs that display the whole classification of the examined papers were used to utilized to arrange the discussion and analysis of the research into such a detailed discussions. It was discovered that Steel alloys are the most commonly used for laser cutting (59%), followed by aluminum alloys (13%) and titanium alloys (12%). While other subjects constitute 16% of research in this field It was also found that The most common parameters utilized as controls are cutting speed (30%), Laser power (23%), Assist gas pressure (21%), Pulse frequency (9%) and Focal position (7%), in general the ideal parameters to achieve low (SR), small (HAZ) width, small (KW) and small (KT) are low (Pu), high (V), medium (P), high (SOD), medium (PF), medium (PW), small (ND), small (T), and N2 as an assist gas.

Abstract: A magnetic resonance imaging contrast agent is proposed using iron oxide nanoparticles (IONPs) synthesized by a pulsed laser ablation technique. Experimentally, an Nd: YAG laser (1064 nm, 7 ns, 30 mJ) was directed and focused on a high-purity iron plate immersed in a liquid solution of deionized water and polyvinylpyrrolidone (PVP). After a few minutes of laser bombardment, iron oxide nanoparticles dispersed in the liquid were homogeneously produced. A reddish yellow color-colloidal IONPs are produced in the water, while its color changes to dark brown for the PVP solution. The characterization results demonstrated that IONPs in the form of Fe₂O₃ and Fe₃O₄ made in the PVP have an excellent dispersibility with a spherical shape that is significantly smaller than that of IONPs made in the deionized water at the same laser repetition rate. The produced IONPs are further applied as a contrast agent for the magnetic resonance imaging (MRI) modality by varying concentrations from 0.05 mM to 2.31 mM. The results demonstrated that images of the IONPs sample with a concentration of 2.31 mM showed the highest contrast enhancement (Cenh), with an enhancement factor of 221.875 % for T₁-weighted images and 91.227 % for T₂-weighted images. IONPs with a concentration of 2.31 mM had the highest signal-to-noise ratio (SNR) for a T₁-weighted picture of 52.92, while IONPs with a concentration of 0.05 mM had the highest SNR for a T₂-weighted image of 179.117.

Abstract: Polypyrrole (PPy), functionalized multi-walled carbon nanotube (f-MWCNT), nickel oxide (NiO) nanocomposites (NCs) films did prepare by PLD technique. The weight percentage of PPy/ f-MWCNT varied from 1 to 5 wt.% whereas NiO fixed with 8wt.%. The nanocomposite films were characteristics by XRD, Raman, FTIR, SEM, and EDS. The XRD pattern shows that the films of (NCs) indicating the amorphous structure of PPy and polycrystalline cubic crystal of NiO and hexagonal phase of f-MWCNT. The dominant phase for (NCs) represented by (002) for f-MWCNT, NCs were shifted to different values of 2θ. Raman spectroscopy the characteristics peaks of (G-D) band at (1280,1320,1570,1610) and the intensity increases with concentration increase to the NCs. FTIR spectra of (NCs) films, refer that C2 has a prominent absorption peak at 1292 cm^-1 and C4 at 1550 cm^-1 indicated the spectrum of PPy/NiO and from C1 at 2360 cm⁻¹ and C4 at 709 cm⁻¹ indicated the spectrum of PPy/CNT. The morphological studies revealed that tubular surface structure at (C1, C3, and C5) and cluster branching in (C2, C4). It shows agglomeration particles and porosity for the surface of the (NCs) films. For all measurements, the (NCs) succeeded in making the nanoparticles (f-MWCNT/NiO) held together in the polymer (PPy) matrix indicating, that a good interlinkage between PPy, f-MWCNT, and NiO. Keywords: PPy/f-MWCNT/NiO nanocomposites, pulsed laser deposition, Nd:YAG Laser.

Abstract: Tin oxide nanoparticles (SnNPs) are very useful to be employed as an antibacterial agent for both gram-positive and gram-negative bacteria. In this present work, the synthesis of SnNPs was successfully carried out using the neodymium yttrium aluminum garnet (Nd:YAG) laser with a wavelength of 1064 nm, pulse duration of 7 ns, and a laser frequency of 10 Hz. Experimentally, a pulse Nd:YAG laser was directed and focused on a high-purity tin (Sn) metal, immersed in various liquid media including pure water and ethylene glycol. A brownish colloidal colour was produced both in pure water and ethylene glycol liquid media. Characterizations of tin oxide nanoparticles were made using UV-Vis, EDX, FTIR, and TEM. UV-Vis characterization produced absorbance values in pure water and ethylene glycol media of 1.314 a.u. and 1.119 a.u., respectively. TEM images show that the shape of tin oxide nanoparticles produced is spherical. Measurement of nanoparticle size distribution was made using image-J software and the average diameter of nano-size in the ethylene glycol medium is 12.55 nm, which is smaller than the size in the pure water of 19.98 nm. The EDX spectrum analysis results show that there are only Sn and O atoms in colloidal tin oxide nanoparticles (SnNPs). FTIR results show the formation of tin oxide (SnO₂) spectrum at the wavenumber of 629.03 cm^-1. The produced colloidal SnNPs were then applied as an antibacterial agent of E. coli using the disk diffusion method. Results certified that various concentrations of SnNPs of 10 ppm, 20 ppm, and 30 ppm gain the diameter of inhibition zone (DIZ) in sequence 6.50 mm, 6.75 mm, and 9.50 mm. Based on these experimental results, it shows that the higher the concentration of SnNPs given, the greater the ability to degrade and inhibit bacteria.

Abstract: Copper nanoparticles were synthesized using laser ablation method by the reduction of copper plate in the presence of distilled water. Effects of time as the laser hits on the copper target were increased, the amount of Cu NPs in the distilled water also increased. EDAX confirms the existence of Cu NPs. The metallic nanoparticles have a unique optical property known as Surface Plasmon Resonance (SPR) which can be utilized to enhance the light harvesting performance in many applications. The noble metals of copper have the ability to support surface plasmon resonance which can be used to enhance the efficiency of any device.

Abstract: The aim of this study is to show the possibility to control structural and optical properties of Au nanoparticles (AuNPs) by changing their size and concentration and make comparison between methods of their formation. 1.4 nm thick Au films were formed on borosilicate glass substrates by the vacuum evaporation method. AuNPs were formed on the surface of the substrate by two methods. First is the irradiation by the Nd:YAG laser pulses with intensities from 75 to 180 MW/cm². Second is thermal annealing, at temperature T=400 °C and the time of curing was varied from 24 to 72 hours. The irradiation of Au film by laser leads to formation of AuNPs. The increase of intensity of laser radiation causes the disappearing of small Au nanoparticles and growing of big nanoparticles from 113-180 nm due to the agglomeration of small particles into big ones and, correspondingly, concentration of particles decreases. In contrast, thermal annealing at T=400 °C from 48 to 72 hours leads to the island formation with the non-spherical shape and their dividing into several islands according to the spinodal dewetting model. As a result, the mean diameter of AuNPs is decreased from 161 to 85 nm but concentration increases.

Abstract: In the application of laser marking, the biggest challenge is that machine-readable barcodes with superior quality were not marked consistently. To solve this problem, laser direct-part marking Data Matrix barcode experiments were carried out on titanium alloy substrates, using a Q-switched light-pumped Nd:YAG laser. The microstructure of the symbols was analyzed using an environmental scanning electron microscope (ESEM). The internal micro-stresses of the marked areas were analyzed using X-ray diffractometer (XRD). The influence of the pulse frequency on the symbol contrast is analyzed. Results showed the interaction between the laser and the titanium alloy can be found. This can further explain the physical mechanism of laser direct part marking Data Matrix symbols on titanium alloy substrates.

Abstract: The influences of laser processing parameters on the symbol contrast and surface roughness of Data Matrix barcodes were studied by single factor experiments using a Q-switched lamp pumped Nd:YAG laser. The orthogonal experiments were carried out to further study the relationship between laser parameters and surface roughness. Multivariate nonlinear regression analyses were performed based on the orthogonal experimental results and a mathematical relationship between parameters and surface roughness was established. The results show that the change trend of surface roughness is similar to symbol contrast with the increase of laser parameters. Both the average power and two different overlaps are important factors affecting the surface roughness and symbol contrast. But the current intensity has an insignificant impact on the surface roughness. The developed regression model can be used to predict the roughness of Data Matrix barcodes. This study can improve industrial application of laser direct part marking technology on titanium alloy substrates.

Abstract: A possibility to improve the quality of polycrystalline CdS thin film by Nd:YAG laser irradiation was shown. The CdS thin film was prepared by closed space sublimation method on ITO/glass structure and irradiated by Nd:YAG laser with intensity up to 15 MW/cm². Several evidences demonstrated the improvement of the optical properties of the CdS thin film after the laser radiation: appearance of photoluminescence band at ~2.530 eV, which is attributed to bound exciton emission; appearance of “spike” in the reflection spectrum at ~2.573 eV between upper and lower polariton branches and the increase intensity of LO phonon line at 305 cm^-1 about 3 times in Raman back scattering spectra. Moreover, the increase by 20% of the size of crystals in CdS after laser radiation takes place, which was proved by using X-Ray diffraction analysis.

Abstract: The enhancement of CdZnTe crystal resistivity by λ=1064nm Nd:YAG laser radiation was shown. This effect is explained by compensation of cadmium vacancy (V_Cd) by indium atoms due to a laser-induced temperature gradient around Te inclusions. The temperature gradient is caused by the selective absorption of the laser radiation by the Te inclusions.