CW YAG Laser Research Articles

Assessment of the non-linear optical behavior of cells for discrimination between normal and malignant glial cells

Cancer patients who have a diagnosis in the early stage of the disease have better chances for therapy. Thus, development of new diagnostic procedures is needed for the early detection of cancer. Measuring and analyzing the light that is scattered by the cells can be utilized to monitor early variations associated with cancer evolution. The key hypothesis behind this research was the application of the Z-scan method to progress the precision of detecting the C6 glioblastoma multiforme cancer cells and the OLN-93 normal glial cells.A Nd:YAG CW laser with a wavelength of 532 nm was used. The laser beam passed through the prepared samples and the transmittance power is distinguished by dislocation. Finally, the nonlinear refractive index and the extinction coefficient of the samples were determined.Our study showed that the extinction coefficient of the C6 and OLN-93 cells were 49 ± 3 and 33 ± 2, respectively. Also, the sign and value of the nonlinear refractive index (n2) for the C6 and OLN-93 cells was −5.44 × 10−7 cm2 w−1 and +6.07 × 10−7 cm2 w−1, respectively. According to this study, the sign of the n2 index for the C6 and OLN-93 cells was negative and positive, respectively.Our results suggested that the nonlinear refractive index of the cell samples and Z-scan technique could be an applicable means for identifying glial cancer cells from normal cells.

Quenching of Р6М5 High-Speed Steel by a Yb:YAG CW Laser

The quenching of annealed Р6М5 high-speed steel by a constant-action ytterbium fiber laser (a Yb:YAG CW laser) is studied. The optimal conditions for laser quenching of Р6М5 high-speed steel are found to be as follows: laser-spot diameter 2 mm; speed 0.4 cm/s; and power density 10 kW/cm2. In those conditions, Р6М5 high-speed steel is quenched to hardness 58–60 HRC.

Synthesis, spectroscopic characterization and determination of the nonlinear optical properties of 2-(4-chlorobenzylidene) malononitrile using a computational method and Z-scan technique

A synthesis and theoretical study was carried out on UV-vis spectra of 2-(4-chlorobenzylidene) malononitrile. The structure, the geometry optimization, and the properties of non-linear optics were also investigated using the theory level M062X/6311 + +G (d, p). The Z-scan technique was used to establish the optical properties of 4ClD2MM as a function of the laser emission power; said compound was diluted in tetrahydrofuran to a fixed concentration of 0.1 M. By means of the same technique it was possible to establish non-linear parameters such as the non-linear refractive index, the non-linear absorption coefficient and the electronic third-order susceptibility. For these measurements, a Nd: YAG CW laser was used emitting at 532 nm, as well as a focus of a 10 cm lens, a 1 mm iris and a cell with a length of 1 mm.

Synthesis and investigation of nonlinear optical properties of Para Red: Z-scan technique and quantum mechanical calculations

Abstract In this study, we present a systematic study of linear and nonlinear optical properties of Para Red with the aim of Z-scan technique and quantum mechanical calculations. The Z-scan experiments were performed using a 532 nm Nd: YAG (SHG) CW laser beam. Para Red exhibited a strong nonlinear refractive index, nonlinear absorption coefficient and third-order nonlinear susceptibility 3.487 × 10−6 cm2/W, 2.341 × 10−1cm/W and 2.157 × 10−4 esu, respectively. Also, quantum chemical analysis was used for the calculation of the dipole moment μ, dipole polarizability α, anisotropy of polarizability Δα and molecular hyperpolarizabilities (β,γ). The results revealed that Para Red has large first and second hyperpolarizabilities. However, from the obtained results, it was found that Para Red can be a promising material for applications in the development of non-linear optical materials.

Synthesis of highly stable silver nanoparticles through a novel green method using Mirabillis jalapa for antibacterial, nonlinear optical applications

Green synthesis techniques are developing as more simplistic and eco-friendly approach for the synthesis of metal nanoparticles compared to chemical reduction methods. Herein we report Synthesis of highly stable silver nanoparticles using Mirabillis jalapa seed extract as a reducing and capping agent. The as-prepared silver nanoparticles were characterized by UV–vis spectroscopy (UV–vis) to confirm the formation of silver nanoparticles by its characteristic surface plasmon resonance peak observed at 420 nm. The Powder X-ray diffraction (P-XRD) revealed the structure and crystalline nature of synthesized silver nanoparticles, The Fourier transform infra-red spectroscopic (FT-IR) revealed the presence of the biomolecules in the extract that acted as reducing as well stabilizing agent. The high resolution transmission electron microscopic (HRTEM) images divulged that the synthesized silver nanoparticles were spherical in shape and poly dispersed. The energy dispersive X-ray diffraction (EDX) profile revealed the elements present in the as-synthesized colloidal silver nanoparticles and its percentages. The Zeta potential measured for silver nanoparticles evidenced that the prepared silver nanoparticles owned high stability in room temperature itself. The as-synthesized silver nanoparticles (AgNPs) in colloidal form were showed good antimicrobial effects and it's were found to exhibit third order optical nonlinearity as studied by Z-scan technique using 532 nm Nd:YAG (SHG) CW laser beam (COHERENT—Compass 215 M-50 diode pumped) output as source. The negative nonlinearity observed was well utilized for the study of optical limiting behavior of the silver nanoparticles.

Synthesis of silver nanoparticles through green approach using Dioscorea alata and their characterization on antibacterial activities and optical limiting behavior

In this work, we have successfully synthesized highly biocompatible and functionalized Dioscorea alata (D. alata) mediated silver nanoparticles with different quantities of its extract for the evaluation of proficient bactericidal activity and optical limiting behavior. The crystalline nature of the synthesized silver nanoparticles was confirmed by powder X-ray powder diffraction (XRD) analysis and furthermore confirmed from SAED pattern of HRTEM Analysis. The Surface Plasmon Resonance band was measured and monitored by UV–Visible spectral studies. The functional groups present in the extract for the reduction and stabilization of the nanoparticles were analyzed by Fourier transform infrared spectroscopy (FTIR) technique. Surface morphology and size of particles were determined by high-resolution transmission electron microscopy analysis (HRTEM). The elemental analysis was made by Energy Dispersive X-ray Spectroscopy (EDX). The synthesized silver nanoparticles (AgNPs) in colloidal form were found to exhibit third order optical nonlinearity as studied by closed aperture Z-scan technique and open aperture technique using 532nm Nd:YAG (SHG) CW laser beam (COHERENT—Compass 215M-50 diode-pumped) output as source. The negative nonlinearity observed was well utilized for the study of optical limiting behavior of the silver nanoparticles. D. alata mediated silver nanoparticles possess very good antimicrobial activity which was confirmed by agar well diffusion assay method.

All-Optical Surface Micropatterning by Electric Field Intensity Gradient

In this report an all-optical photo-induced formation of surface relief gratings is shown. For the surface patterning of As2S3 and As4S1.5Se4.5 films a direct holographic recording setup with a 532 nm wavelength Nd:YAG CW laser light was used. Our investigations have shown that the light-induced mass transfer process strongly depends on the material itself and on the polarization of the light. It has been shown that an electric field intensity gradient has to be obtained to achieve a direct patterning. The evolution of a surface relief in relation to recording parameters and thickness of the sample has been investigated in detail.

The acoustical sensor: The photoacoustic effect in an azo-dye

The photoacoustic (PA) signal of DR1 dye in six solvents with different polarity, density and the coefficient of viscosity were investigated by a simple experimental set up. The measurements were performed at 532 nm using a Nd; YAG CW laser with irradiation of 300 mW. In the middle of experiment, A sound produced when the sample exposed to the laser irradiation at a critical power therefore it acts as an acoustic sensor. It is demonstrated that the maximum photoacoustic frequency amplitude of PA in an exact frequency has an inverse proportion to viscosity coefficient of solvents and verify the theoretical equations.

Investigation of the optical bistability in the PMMA polymer doped with MNA

The optical bistability (OB) of PMMA polymer doped with 2-Methyl-4-Nitroaniline (MNA) thin films on Mach–Zehnder interferometer nonlinear ring cavity with applied external feedback was investigated in five thicknesses. The measurements were performed at 532nm using a Nd:YAG CW laser with irradiation of 300mW. An optical bistability hysteresis was obtained because of charge transfer in benzene ring in MNA's structure. It is demonstrated that although, the gain of optical bistability improved using external feedback for thinner samples. While, in thicker samples, the local thermal effect decreased the gain and had negative effect on OB.

3kW liquid-cooled elastically-supported Nd:YAG multi-slab CW laser resonator.

A 3kW liquid-convection-cooled Nd:YAG CW laser resonator with a novel design is developed and demonstrated, in which the straight-through geometry is adopted that the oscillating laser propagates through multiple thin slabs and multiple cooling flow layers in Brewster angle. Using the elastically-supported Nd:YAG single-crystal thin slabs at different doping levels, a multimode laser output with the output power of 3006 W is obtained from the stable cavity at the pump power of 19960 W, corresponding to an optical-optical efficiency of 15.1%, and a slope efficiency of 21.2%.

Corrosion and wear resistance improvement of magnesium alloys by laser cladding with Al-Si

Laser cladding with Al-Si powders have been carried out on three different magnesium alloys (AZ61, ZK30 and WE54) in order to improve their wear and corrosion properties using Nd:YAG CW laser. Optimized parameters allow obtaining crack and pore free coatings with good metallurgical bonding. Special care in shielding atmosphere is required to avoid porosity and corrosion. The hardness of the coatings is higher (130-250 HV) than that of as-received alloys. Salt spray corrosion tests and pin on disc sliding wear tests were carried out confirming that Al-Si coatings improves the wear and corrosion resistance of the alloys.

Laser manipulation of micro untransmissive particles in water

The laser trapping of untransmissive particles are discussed in this paper. Photon can generate the momentum to the untransmissive particle by diffraction and reflection on the surface of the particles. We tried laser trapping of untransmissive particles using an attractive force caused by the diffraction and radiation force caused by reflection. The laser trapping system includes CW YAG laser, which has 1.064 μm in wave length and an optical microscope. The motions of particles were monitored by a CCD camera on the top of the microscope and recorded by PC connected to the CCD camera.

21110 微小液滴中固体微粒子のレーザマニピュレーション(MEMS技術,OS.3 機械工学が支援する微細加工技術(半導体,MEMS,NEMS))

The laser trapping of untransmissive solid particles are disscussed in this paper. Photon can generate the momentum to the untransmissive particles by diffraction and reflection on the surface of the particles. We tried laser trapping of untransmissive particles using an attractive force caused by the diffraction and radiation force caused by reflection. The laser trapping system contains CW YAG laser. which has 1.064 μm in wave length and an optical microscope. The motions of particles were monitored by a CCD camera on the top of the microscope and recorded by PC connected to a CCD camera.

Laser Forming of Tailored Blanks of High Tensile Strength Steels

Tailor welded blanks with two different materials (SPCC-SPFC980Y) were V bent by laser forming which is a bending method with thermal stress induced by rapid heating by means of laser irradiation, and it is suitable for bending of large spring back sheets since spring back is not affected. Forming conditions for SPCC part and SPFC980Y part were changed. A 50W CW YAG laser was employed with laser scanning number of 10 and defocus length of 25mm. When same laser power (38W) was employed for SPCC and SPFC980Y parts, bending angle of SPCC part was greater than that of SPFC980Y part. However, when laser power was 40W for SPFC980Y part and 36W for SPCC part, the bending angle of both parts were almost same and this means constant bending angle was obtained by controlling the laser power. Uniform bending angle was also obtained by controlling the laser scanning velocity as well as the laser power.

Nonlinear optical responses of Sudan IV doped liquid crystal by z-scan and moiré deflectometry techniques

The nonlinear optical properties of a nematic liquid crystal doped with an azo dye were investigated. The magnitude and the sign of the third-order nonlinear refractive index, n 2, were measured using both single-beam z-scan and moiré deflectometry techniques. The measurements were performed at 532 nm using a Nd:Yag CW laser. The positive sign showed that sample which was studied possess a self-focusing optical nonlinearity. Rather close agreement was found between the values for n 2 obtained by z-scan and by moiré deflectometry. The nonlinear refractive index was found to be in the order of 10 − 6 (cm 2/W) and the nonlinear absorption coefficient to be β = 0.171 (cm/W).

Fabrication of Conductors and Inductors by Nano-Particle Deposition through Direct Write Technology

Direct Write Technologies are being utilized in antennas, engineered structures, sensors, and tissue engineering. One form of the Direct Write Technologies is Maskless Mesoscale Material Deposition (M3D) for Optomec, Inc. M3D is a process that uses aerosol formation, transport and deposition. Inks for the M3D utilize nano-particles in suspension for deposition. Several different conductive inks were deposited with M3D and characterized for electrical resistivity and microstructure. Soft magnetic material was formulated as an ink suspension, deposited and characterized. This paper will report on the results obtained after sintering conductive nano-particle inks and soft magnetic material. Sintering was performed with a 2W frequency doubled Nd:YAG CW laser, a conventional muffle furnace and a novel photonic curing method. Depositions of various conductive inks were examined for physical dimensions (width and thickness) and microstructure. A study of the sintering characteristics if these ink was also included. This paper will also report on the results obtained from depositing a soft magnetic material. Permeability results were calculated from magnetic structures created with the deposition. These results are compared to conventional methods of soft magnetic material formation and construction. Physical properties of the deposited inks are also measured and reported.

Experimental study of the dynamical coupling between the induced vapour plume and the melt pool for Nd–Yag CW laser welding

We discuss the effects of the interaction between the vapour generated by the ablation process occurring on the front keyhole wall (KW) during deep penetration Nd–Yag laser welding and the surrounding metallic melt pool. It is shown that the inclination of the front KW determines the importance of this process. At low welding velocities, the front KW inclination is small and therefore the drag forces induced by the expanding vapour accelerates a liquid thin film around the keyhole and parallel to its axis. At high welding velocities, the front KW inclination becomes large, and the evaporation process is very important. Therefore the expanding metallic vapour impinges on the rear KW and opens the keyhole aperture. These effects localize the droplet generation process. By using an adequate side gas jet nozzle, we show that we can stabilize the melt pool fluctuations, and therefore suppress droplet generation and improve the weld seam quality.

2610 構成材料の違いによるレーザトラッピンク研究(S44-1 マイクロ気泡・粒子,S44 マイクロ・ナノフルイディクス)

The laser trapping on metal solid particles are discussed in this paper. Photon can generate the momentum to the untransparent particle by diffraction and reflection on the surface of the particles. We tried laser trapping of untransparent particles using an attractive force caused by the diffraction and radiation force caused by reflection. The laser trapping system contains CW YAG laser, which has 1.064 micron in wave length and an optical microscope. The motions of particles were monitored by a CCD camera on the top of the microscope and recorded by PC connected to the CCD camera. The particles were at first scattered in a droplet placed on a slide glass and a stage was used in order to move the slide glass.

Laser Weldability of Aluminum Alloy and Steel

With the intention of improving butt or lap joint of dissimilar materials, specially devised weld beads together with lap and butt-joints were produced between A5052 and SPCC, where A5052 butt-joint was melted by heat-conduction of SPCC weld bead in addition to the formation of a limited weld fusion zone at the lap part in A5052 alloy. The thickness of intermetallic compounds at the butt-joint interface was approximately 2 μm and free of cracks. It was also revealed that crack-free lap weld metals were formed between aluminum alloy and steel when the penetration was controlled to be of less than 0.3 mm in depth at small heat input. It was moreover found that the majority of a laser weld fusion zone solidified as alpha(bcc)-iron phase containing small amount of aluminum, and cracks were absent in the case of hard intermetallic (AlxFey type) layer of less than 10μm zone. It was confirmed that a weld with lap and butt joints possessed high strength (leading to the load 3500 N to 4,380 N for 40 mm width specimen). In addition, SPCC and A1100 or A5052 were subjected to lap welding with a cw YAG laser, where one to three passes were performed to produce wider bonded areas. Dissimilar steel and aluminum joints with good mechanical properties were obtained, since the fracture occurred in the aluminum alloy base metal in the tensile test. It is concluded that welded joints of high strength can be produced between aluminum alloy and steel with proper devices.

Study of keyhole behaviour for full penetration Nd–Yag CW laser welding

The understanding of keyhole behaviour is still a topic of great importance. The keyhole dynamics can be rather easily analysed in the case of full penetration laser welding experiments. Moreover, this configuration can allow an easy access to the complete keyhole geometry, if thin metallic sheets are welded. Indeed, in this case, only one laser beam reflection occurs on the front keyhole wall (KW). We present the results of the study of these welding configurations, where a Nd : Yag laser with a top-hat intensity distribution is considered. Several diagnostics have been used. For different experimental conditions, the dynamics of the keyhole and its complete geometry (front wall inclination, top and bottom apertures) have been analysed by using on axis visualizations through the top and the bottom of the keyhole with a 4 kHz high speed video camera. The measurement of the transmitted laser power also gives access to the front KW reflectivity. These results are compared and are used to validate our dynamic keyhole modelling, where ray tracing is included. Finally, for these conditions, an analytical model can be proposed that relates the laser parameters (incident laser power, spot diameter) with the processing parameters (material, sheet thickness and welding velocity) for Nd–Yag laser welding.