Simple Defocus Laser Irradiation to Suppress Self-Absorption in Laser-Induced Breakdown Spectroscopy (LIBS)

This study introduces a novel and extremely simple way for suppressing the self-absorption effect in laser-induced breakdown spectroscopy (LIBS) by utilizing a defocusing laser irradiation technique. It is claimed that defocusing laser irradiation produces more uniform laser plasma due to lower fluence than tight focus laser irradiation, hence greatly lowering the effect of self-absorption in the laser plasma. KCl and NaCl pellet samples were used to demonstrate this achievement. When the defocus position is adjusted to – 6 mm for KCl and NaCl samples, the self-reversal emission lines K I 766.4 nm, K I 769.9 nm, Na I 588.9 nm, and Na I 589.5 nm vanish. Meanwhile, the FWHM values of K I 766.4 and K I 769.9 nm are 0.29 nm and 0.23 nm, respectively, during -6 mm defocus laser irradiation, as opposed to 1.24 nm and 0.86 nm, under tight focus laser irradiation. Additionally, this work demonstrates that when the laser energy is changed in between 10 to 50 mJ, no self-reversal emission occurs when -6 mm defocus laser irradiation is applied. Finally, a linear calibration curve is generated using KCl at a high concentration ranging between K concentration from 16.6–29%. This simple change of defocus laser irradiation will undoubtedly contribute to the suppression of the self-absorption phenomenon, which disrupts LIBS analytical results.

APPLICATION OF DIFFRACTIVE OPTICAL ELEMENTS FOR OPTICAL-ELECTRONIC DIMENSIONAL INSPECTION SYSTEMS

The work is devoted to the application of diffractive optical elements in systems using the structured illumination method to the geometric parameters inspection of industrial articles. The objects of inspection in these systems are: weapon barrels, fuel pellets, fuel elements, spacer grids, ceramic ring insulators. The used diffractive optical elements are computer-synthesized holograms that focus laser radiation into geometric shapes, the configuration of which is optimally combined with the inspected objects shape.

The first experience of applying laser ablation in patients with benign tumors, tumor-like and inflammatory diseases of the skeleton

The researchers discuss the first experience of treating 9 pediatric patients with osteoid osteoma (3), primary chronic osteomyelitis (4) and aneurysmal cysts (2). Selected patients had complex treatment which included unloading of the diseased segment of the skeleton and laser ablation of the pathological focus. Laser ablation was done with medical laser «AZOR-ALM», emitting light at wavelength 1.55 μm. Registration certificate No. RZN 2015/2720 of Roszdravnadzor. Manufacturer – LLC «AZOR» (Moscow). Small tumors and inflammatory diseases of the skeleton were surgically treated with high-level laser light in the computed tomography room. Patients with lesions of lower extremities and pelvis previously had spinal anesthesia. If a pathologic focus was located in bones of upper extremities, regional brachial plexus blockage was preferable. In all cases, positive outcomes were seen. Follow-up lasted for 6 months.

Microscope objectives

Microscope objectives are key components of optical microscopes, but they also equip experimental set-ups to focus laser beams or to collect photons emitted from any physical events to analyze or to diagnose. There are properties to take into account about their specifications and their usage for selecting the right microscope objective. They are used in a wide range of applications, from life sciences to material sciences, in laboratories and in industries and each application requires a specific microscope objective.

Photovoltaic and Physical Characteristics of Screen-Printed Monocrystalline Silicon Solar Cells with Laser Doping and Electroplated Copper

Photovoltaic and physical characteristics of screen-printed monocrystalline silicon solar cells (SPMSCs) were presented with electroplated copper (EPC) as the rear contact. The boron back surface field (B-BSF) formed by spin-on doping and laser doping (LD) was prepared as a seed layer for the EPC. The LD parameters, including the laser focus, laser power, laser speed, and laser line pitch, were investigated. Moreover, the effects of KOH etching on the surface properties after the LD process were explored. Furthermore, to enhance the adhesion between the B-BSF seed layer and EPC contact layer, a laser pinhole process was proposed. Finally, the EPC processes with various electroplating times were addressed. The results revealed that the mechanism of enhancements could be attributed to a continuous B-BSF seed layer and a reduction of series resistance, as well as an increase of open-circuit voltage and adhesion between the B-BSF seed layer and EPC contact layer.

Percolated Si:SiO2 Nanocomposites: Oven- vs. Millisecond Laser-Induced Crystallization of SiOx Thin Films

Three-dimensional nanocomposite networks consisting of percolated Si nanowires in a SiO2 matrix, Si:SiO2, were studied. The structures were obtained by reactive ion beam sputter deposition of SiOx (x ≈ 0.6) thin films at 450 ∘C and subsequent crystallization using conventional oven, as well as millisecond line focus laser treatment. Rutherford backscattering spectrometry, Raman spectroscopy, X-ray diffraction, cross-sectional and energy-filtered transmission electron microscopy were applied for sample characterization. While oven treatment resulted in a mean Si wire diameter of 10 nm and a crystallinity of 72% within the Si volume, almost single-domain Si structures of 30 nm in diameter and almost free of amorphous Si were obtained by millisecond laser application. The structural differences are attributed to the different crystallization processes: conventional oven tempering proceeds via solid state and millisecond laser application via liquid phase crystallization of Si. The five orders of magnitude larger diffusion constant in the liquid phase is responsible for the three-times larger Si nanostructure diameter. In conclusion, laser treatment offers not only significantly shorter process times, but moreover, a superior structural order of nano-Si compared to conventional heating.

Percolated Si:SiO2 Nanocomposites: Oven- vs.Millisecond Laser-induced Crystallization of SiOx Thin Films

Three-dimensional nanocomposite networks consisting of percolated Si nanowires in a SiO2 matrix, Si:SiO2, were studied. The structures were obtained by reactive ion beam sputter deposition of SiOx (x ≈ 0.6) thin films at 450 °C and subsequent crystallization using conventional oven as well as millisecond line focus laser annealing. Rutherford backscattering spectrometry, Raman spectroscopy, X-ray diffraction, cross-sectional and energy-filtered transmission electron microscopy were applied for sample characterization. While oven annealing resulted in a mean Si wire diameter of 10 nm and a crystallinity of 72 % within the Si volume, almost single-domain Si structures with 30 nm in diameter and almost free of amorphous Si were obtained by millisecond laser application. The structural differences are attributed to the different crystallization processes: Conventional oven tempering proceeds via solid state, millisecond laser application via liquid phase crystallization of Si. The 5 orders of magnitude larger diffusion constant in the liquid phase is responsible for the three times larger Si nanostructure diameter. In conclusion, laser annealing offers not only significantly shorter process times but moreover a superior structural order of nano-Si compared to conventional heating.