scholarly journals Laser-Assisted Thermal Imprinting of Microlens Arrays—Effects of Pressing Pressure and Pattern Size

Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 675 ◽  
Author(s):  
Keisuke Nagato ◽  
Yuki Yajima ◽  
Masayuki Nakao
Keyword(s):  
Laser Irradiation ◽  
Polymer Films ◽  
Printed Electronics ◽  
Irradiation Time ◽  
Filling Ratio ◽  
Pressing Pressure ◽  
Cross Sectional ◽  
Microlens Arrays ◽  
Pitch Pattern ◽  
Pattern Size

Polymer films with nano- or microstructured surfaces have been widely applied to optical devices, bioplates, and printed electronics. Laser-assisted thermal imprinting (LATI), in which a laser directly heats the surfaces of a mold and a thermoplastic polymer, is one of the high-throughput methods of replicating nano- or microstructures on polymer films. Only the surfaces of the mold and polymer film are heated and cooled rapidly, therefore it is possible to replicate nano- or microstructures on polymer films more rapidly than by using conventional thermal nanoimprinting. In this study, microlens arrays (MLAs) were replicated on polymethylmethacrylate (PMMA) films using LATI, and the effects of the pressing pressure (10−50 MPa) and the pattern size (33- and 5-μm pitch) of the MLA on the filling ratio were investigated by analyzing a microlens replicated using different laser-irradiation times (0.1−2 ms). The filling ratio increased with increasing pressing pressure and laser-irradiation time in the replication of MLAs with varying sizes, while the flow of the PMMA varied with the pressing pressure and laser-irradiation time. It was found that during filling, the shape of the polymer cross-sectional surface demonstrated a double and single peak in the 33- and 5-μm-pitch patterns, respectively. This was because the depth of the heated area in the 33-μm-pitch pattern was smaller than the pattern size, whereas that of the 5-μm-pitch pattern was comparable to (or larger) than the pattern size.

Effect of Pre-Oxidized CuO Layer in Joining between Polyethylene Terephalate (PET) and Copper (Cu) by Using Pulsed Nd:YAG Laser

2010 ◽  
Vol 129-131 ◽  
pp. 714-718 ◽  
Author(s):  
Farazila Yusof ◽  
Yoshiharu Mutoh ◽  
Yukio Miyashita
Keyword(s):  
Laser Irradiation ◽  
Nd:Yag Laser ◽  
Shear Failure ◽  
High Heat ◽  
Experimental Result ◽  
Joint Interface ◽  
Intimate Contact ◽  
Cross Sectional ◽  
Pulsed Nd:Yag Laser ◽  
Oxide Particles

In the present study, effect of pre-oxidized (PO) CuO layer in the joining between polyethylene terephalate (PET) and copper (Cu) by using pulsed Nd:YAG laser was investigated. The experimental result for PET/PO Cu (with pre-oxidized layer) and PET/Cu (without pre-oxidized layer) were presented in this paper. The results showed the pre-oxidation surface improved the welding efficiency. The welded area and tensile shear failure load (TSFL) of PET/PO Cu joint were increased when pre-oxidized layer was introduced. This indicates that high heat was absorbed during laser irradiation of PET/PO-Cu joint compare to PET/Cu joint. On the other hand, the fracture surface of PET/PO-Cu showed the presence of Cu and Cu oxide particles in the PET side. While in case of PET/Cu, no occurrence of Cu particles can be observed. The presence of Cu oxide particles and Cu particles were believed may increase PET/PO Cu joint shear force. From the cross-sectional observation of PET/PO Cu joint interface, it was found that an oxide layer in the laser irradiation area was removed and PET seemed to have intimate contact with Cu surface.

scholarly journals Laser-Induced Modification of Hydrogenated Detonation Nanodiamonds in Ethanol

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2251
Author(s):  
Irena Bydzovska ◽  
Ekaterina Shagieva ◽  
Ivan Gordeev ◽  
Oleksandr Romanyuk ◽  
Zuzana Nemeckova ◽  
...  
Keyword(s):  
Surface Chemistry ◽  
Laser Irradiation ◽  
Structural Changes ◽  
Irradiation Time ◽  
Detonation Nanodiamonds ◽  
High Temperature Annealing ◽  
Inert Environment ◽  
Transmission Electron ◽  
Gradual Loss ◽  
532 Nm

Apart from the frequently used high-temperature annealing of detonation nanodiamonds (DNDs) in an inert environment, laser irradiation of DNDs in a liquid can be effectively used for onion-like carbon (OLC) formation. Here, we used fully de-aggregated hydrogenated DNDs (H-DNDs) dispersed in ethanol, which were irradiated for up to 60 min using a 532 nm NdYAG laser with an energy of 150 mJ in a pulse (5 J/cm2) at a pulse duration of 10 ns and a repetition rate of 10 Hz. We investigated the DND surface chemistry, zeta potential, and structure as a function of laser irradiation time. Infrared spectroscopy revealed a monotonical decrease in the C–Hx band intensities and an increase of the C–O and C=O features. Transmission electron microscopy (TEM) revealed the formation of OLC, as well as a gradual loss of nanoparticle character, with increasing irradiation time. Surprisingly, for samples irradiated up to 40 min, the typical and unchanged DND Raman spectrum was recovered after their annealing in air at 450 °C for 300 min. This finding indicates the inhomogeneous sp3 to sp2 carbon transformation during laser irradiation, as well as the insensitivity of DND Raman spectra to surface chemistry, size, and transient structural changes.

Microstructure Morphology and Mechanical Properties of Steel 30CrMnSiNi2A Irradiated by Continuous Wave Laser

2014 ◽  
Vol 809-810 ◽  
pp. 369-376
Author(s):  
Tao Tao Wu ◽  
Li Jun Wang ◽  
Cheng Hua Wei ◽  
Chun Xu Pan ◽  
Lin Zhu Chen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Laser Irradiation ◽  
Continuous Wave ◽  
Solid Phase ◽  
Irradiation Time ◽  
Coupling Efficiency ◽  
Temperature History ◽  
Brittle Layer ◽  
Microstructure Morphology ◽  
Morphology And Mechanical Properties

Steel 30CrMnSiNi2A slices were irradiated by a continuous wave fiber laser beam with the intensity of 14.5W/cm2. Alloy samples with various temperature processes were obtained by changing the laser irradiation time, irradiation times and atmosphere environment. X-ray diffraction, scanning electron microscope, energy dispersive spectrometer and nanoindentation system were employed to characterize their microstructure morphology and mechanical properties. Three layers were observed in the samples fracture, namely oxide film, hard brittle layer and alloy substrate. The hard brittle layer had a higher hardness and a lower toughness compared with the base metal. Referring to the temperature history, we deemed that the surface oxidation and the solid phase transformation were the main factors which changed laser coupling efficiency. The results also illuminated the correlation between the microstructure morphology and the response to laser irradiation of the samples.

scholarly journals On-Chip Multiple Particle Velocity and Size Measurement Using Single-Shot Two-Wavelength Differential Image Analysis

Micromachines ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1011
Author(s):  
Shuya Sawa ◽  
Mitsuru Sentoku ◽  
Kenji Yasuda
Keyword(s):  
Irradiation Time ◽  
Single Shot ◽  
Cross Sectional ◽  
Simple Method ◽  
Quick Measurement ◽  
The Difference ◽  
On Chip ◽  
Calculated Velocity ◽  
Multiple Particle ◽  
Flow Velocities

Precise and quick measurement of samples’ flow velocities is essential for cell sorting timing control and reconstruction of acquired image-analyzed data. We developed a simple technique for the single-shot measurement of flow velocities of particles simultaneously in a microfluidic pathway. The speed was calculated from the difference in the particles’ elongation in an acquired image that appeared when two wavelengths of light with different irradiation times were applied. We ran microparticles through an imaging flow cytometer and irradiated two wavelengths of light with different irradiation times simultaneously to those particles. The mixture of the two wavelength transmitted lights was divided into two wavelengths, and the images of the same microparticles for each wavelength were acquired in a single shot. We estimated the velocity from the difference of its elongation divided by the difference of irradiation time by comparing these two images. The distribution of polystyrene beads’ velocity was parabolic and highest at the center of the flow channel, consistent with the expected velocity distribution of the laminar flow. Applying the calculated velocity, we also restored the accurate shapes and cross-sectional areas of particles in the images, indicating this simple method for improving of imaging flow cytometry and cell sorter for diagnostic screening of circulating tumor cells.

The Influence of Solvents on the Fluorescence Background in Raman Spectroscopy

1987 ◽  
Vol 41 (3) ◽  
pp. 413-416 ◽  
Author(s):  
Sciichiro Higuchi ◽  
Er Jie Yu ◽  
Shigeyuki Tanaka
Keyword(s):  
Laser Irradiation ◽  
Raman Spectra ◽  
Aromatic Compounds ◽  
Irradiation Time ◽  
Polycyclic Aromatic Compounds ◽  
Background Intensity ◽  
Solvent Influence ◽  
Polycyclic Aromatic ◽  
Influence Of Solvents ◽  
Large Background

For the purpose of reducing the fluorescence background induced by the laser irradiation in the measurements of Raman spectra, the influence of solvents on the background intensities for three polycyclic aromatic compounds was examined, where the experiments were conducted with typical solvents. It was demonstrated that the behaviors of the fluorescence background against the laser irradiation time were quite different according to the solvents, and that the behaviors could be classified roughly into the three categories. It was proved that when suitable solvents were used, the background intensities could be reduced sufficiently, even for the fluorescent samples such as those treated here; thus, the clear observation of Raman spectra is obtained. As an example of the solvent influence on the Raman spectra, the results of measurements for three separate cases were shown for 1-nitropyrene. The three cases are as follows: first, the Raman bands are masked almost completely by the strong background (solvent: 1,1,2,2-tetrachloroethane); second, though the spectrum can be obtained, its S/N ratio is low because of the relatively large background (solvent: acetonitrile); third, a clear spectrum with excellent S/N ratio can be obtained because the background intensity is low enough (solvent: carbon tetrachloride).

Effects of increased low-level diode laser irradiation time on extraction socket healing in rats

2013 ◽  
Vol 30 (2) ◽  
pp. 719-726 ◽  
Author(s):  
Joon Bong Park ◽  
Su-Jin Ahn ◽  
Yoon-Goo Kang ◽  
Eun-Cheol Kim ◽  
Jung Sun Heo ◽  
...  
Keyword(s):  
Laser Irradiation ◽  
Diode Laser ◽  
Irradiation Time ◽  
Extraction Socket ◽  
Low Level ◽  
Socket Healing

scholarly journals Laser irradiation of SiC-MoSi2 composite ceramics

2008 ◽  
Vol 40 (3) ◽  
pp. 271-281
Author(s):  
Marquez Aguilar ◽  
M. Vlasova ◽  
M.C. Reséndiz-González ◽  
M. Kakazey ◽  
Mayorga Cruz ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Laser Irradiation ◽  
Irradiation Time ◽  
Composite Ceramics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Ir Laser ◽  
Mosi2 Composite

The influence of continuous IR laser irradiation (? = 1064 nm, P = 240 mW) on SiC-MoSi2 composite ceramics was investigated by X-ray diffraction, electron microscopy, atomic force microscopy, and X-ray microanalysis. The irradiation of specimens was carried out in air. It was established that, due to heating of the surface under laser irradiation, oxidation of SiC and MoSi2 and sublimation of SiO (SiO2) and MoO3 take place. Depending on the content of the components in the ceramics and the irradiation time, SiO2 or MoO3 layers form on the surface or disappear from it. For a long irradiation time, the oxidation and cleaning of the surface (sublimation of oxides) are cyclic in character.

scholarly journals Effect of Diode Low-level Laser Irradiation Time on Socket Healing

2020 ◽  
Vol 21 (6) ◽  
pp. 640-644
Author(s):  
Ali Peimani ◽  
Tahereh Eslammanesh ◽  
Mostafa Sadeghi ◽  
Ramin Rahati
Keyword(s):  
Laser Irradiation ◽  
Irradiation Time ◽  
Low Level ◽  
Low Level Laser ◽  
Level Laser ◽  
Socket Healing ◽  
Low Level Laser Irradiation
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