Search Results (600)

Glass wool waste constitutes a rapidly increasing fraction of construction and demolition residues, yet it remains one of the most challenging insulation materials to recycle. Its non-combustible nature, extremely low bulk density, and high fibre elasticity preclude energy recovery and severely limit conventional mechanical recycling routes, resulting in long-term landfilling and loss of mineral resources. Converting glass wool waste into a fine mineral powder represents a potentially viable pathway for its integration into low-carbon construction materials, provided that industrial scalability, particle-size control, and chemical compatibility with cementitious binders are ensured. This study investigates the industrial-scale milling of end-of-life glass wool waste in a ventilated horizontal ball mill. It compares two grinding routes: a corundum-free route (BK) and an abrasive-assisted route (ZK) employing α-Al₂O₃ corundum to intensify fibre fragmentation. Particle size distribution was quantified by laser diffraction using cumulative and differential analyses, as well as characteristic diameters. The results confirm that abrasive-assisted milling significantly enhances fragmentation efficiency and reduces the coarse fibre fraction. However, the study demonstrates that this gain in fineness is inherently coupled with the incorporation of α-Al₂O₃ into the milled powder, introducing a chemically foreign crystalline phase that cannot be removed by post-processing. From a cement-oriented perspective, this contamination represents a critical limitation, as α-Al₂O₃ may interfere with hydration reactions, aluminate–sulfate equilibria, and microstructural development in Portland and calcium sulfoaluminate binders. In contrast, the corundum-free milling route yields a slightly coarser, chemically unmodified powder, offering improved process robustness, lower operational complexity, and greater compatibility with circular economy objectives. The study establishes that, for the circular reuse of fibrous insulation waste in cementitious systems, particle fineness alone is insufficient as an optimization criterion. Instead, the combined consideration of fineness, chemical purity, and binder compatibility governs the realistic and sustainable reuse potential of recycled glass wool powders. Full article

The macroscopic Fourier ptychography (FP) is regarded as a highly promising approach of creating a synthetic aperture for macro visible imaging to achieve sub-diffraction-limited resolution. However most existing macro FP techniques rely on the high-precision translation stage to drive laser or camera scanning, thereby increasing system complexity and bulk. Meanwhile, the scanning process is slow and time-consuming, hindering the ability to achieve rapid imaging. In this paper, we introduce an innovative illumination scheme that employs a spatial light modulator to achieve precise programmable variable-angle illumination at a relatively long distance, and it can also freely adjust the illumination spot size through phase coding to avoid the issues of limited field of view and excessive dispersion of illumination energy. Coupled with a camera array, this could significantly reduce the number of shots taken by the imaging system and enable a lightweight and highly efficient solid-state macro FP imaging system with a large equivalent aperture. The effectiveness of the method is experimentally validated using various optically rough diffuse objects and a USAF target at laboratory-scale distances. Full article

CO₂ laser processing has emerged as an efficient dry-finishing technique capable of inducing controlled chemical and morphological transformations in cotton and denim textiles. The strong mid-infrared absorption of cellulose enables localised photothermal heating, leading to selective dye decomposition, surface oxidation, and micro-scale ablation while largely preserving the bulk fabric structure. These laser-driven mechanisms modify colour, surface chemistry, and topography in a predictable, parameter-dependent manner. Low-fluence conditions predominantly produce uniform fading through fragmentation and oxidation of indigo dye; in comparison, moderate thermal loads promote the formation of carbonyl and carboxyl groups that increase surface energy and enhance wettability. Higher fluence regimes generate micro-textured regions with increased roughness and anchoring capacity, enabling improved adhesion of dyes, coatings, and nanoparticles. Compared with conventional wet processes, CO₂ laser treatment eliminates chemical effluents, strongly reduces water consumption and supports digitally controlled, Industry 4.0-compatible manufacturing workflows. Despite its advantages, challenges remain in standardising processing parameters, quantifying oxidation depth, modelling thermal behaviour, and assessing the long-term stability of functionalised surfaces under real usage conditions. In this review, we consolidate current knowledge on the mechanistic pathways, processing windows, and functional potential of CO₂ laser-modified cotton substrates. By integrating findings from recent studies and identifying critical research gaps, the review supports the development of predictable, scalable, and sustainable laser-based cotton textile processing technologies. Full article

Over the past 18 months, we have performed hundreds of temperature characterizations of fiber Bragg gratings inscribed in different germanium-doped silica glass fibers. Under experimental conditions, the main conclusions are as follows: the temperature dependence of the “temperature gauge factor” or the normalized temperature sensitivity, K_T, was found to be quadratic in the −50–200 °C range, while it may be considered linear for the −20–100 °C range; K_T values at 20 °C vary from 5.176 × 10⁻⁶ K⁻¹, for a B/Ge co-doped fiber up to 6.724 × 10⁻⁶ K⁻¹, for a highly Ge-doped fiber; K_T does not depend on the hydrogen-loading process or the gratings coupling strength; K_T is essentially independent of wavelength in the 1500–1600 nm range, its value being accurately determined with a relative error ~0.2%; based on the accurate value of K_T = 6.165 × 10⁻⁶ K⁻¹, at 20 °C, obtained for gratings inscribed in the SMF-28 fiber, we calculated a value of 19.4 × 10⁻⁶ K⁻¹ for the thermo-optic coefficient of bulk germanium glass; and gratings produced by femtosecond-laser radiation and UV-laser radiation exhibit comparable values of K_T. The previous achievements allow, by having knowledge of K_T for a single grating, the accurate determination of the temperature dependence of the Bragg wavelength for any other grating inscribed in the same fiber; the presented methodology enables one to determine the “unknown” gratings’ temperature sensitivity, typically with an error of 0.01 pm/°C, being, therefore, very useful in research labs and computer simulations. Thus, expressions for the temperature dependence of K_T for gratings inscribed in several fibers are given, as well as an expression for K_T as a function of the effective refractive index. We have also fully analyzed the potential sources of error in K_T determination. Full article

Recent years have shown that additive manufacturing is able to significantly increase the potential for enhancing lightweight structural design. In particular, strut-based lattices have attracted considerable research interest due to their promising mechanical performance in lightweight engineering applications. While the quasi-static properties of such lattices are relatively well established, their fatigue behavior remains insufficiently understood. This work presents a numerical investigation of the fatigue life of laser powder bed-fused strut-based lattices using the finite element method (FEM). Periodic AlSi10Mg lattice structures with two different unit cells, bcc and $f_{2}c{c}_z$, and three different aspect ratios were analyzed under uniaxial compression–compression loading. The stress-life approach was used to model the fatigue failure of the representative unit cells in the high-cycle fatigue region. The numerical predictions were compared with experimental results, showing good agreement between simulations and physical tests. The findings highlighted that the fatigue response was primarily governed by aspect ratio, unit cell topology, bulk material properties, and mean stress imposed by the load ratio. Moreover, stress concentrations arising from notch effects in the nodal regions were identified as critical fatigue crack initiation sites. Full article

The interaction between laser irradiation and energetic materials is critically influenced by microstructural void defects that determine local energy deposition and initiation sensitivity. In this work, a three-dimensional finite-difference time-domain (3D-FDTD) method was employed to investigate the modulation effects of void defects on optical field distributions and hot spot formation in RDX energetic crystals. The influences of void geometry, spatial position, and void number on the modulation of the incident laser beam were systematically analyzed. It reveals that void defects exhibit strong focusing and scattering behavior, leading to localized high-intensity regions both inside RDX bulk crystals and in void defects. For a single void defect, increasing either the width or depth can significantly enhance the peak electric field and thus the laser sensitivity of RDX crystals. When two voids are present, the number of high-intensity spots first increases and then decreases with increasing separation distance, and the strongest modulation effects are obtained at separations of 0.75λ–3λ. Furthermore, as the number of void defects increases, the modulation effect intensifies, promoting the formation of more hot spots. These findings provide quantitative insight into how void structures govern laser–matter interactions in energetic crystals, offering guidance for understanding and controlling laser initiation behavior. Full article

Polarization beam combining (PBC) is an important technology for enhancing laser brightness. The conventional bulk polarization beam combiners are Brewster plates and birefringent polarization prisms. However, in the mid- and long-wave infrared range, the beam combining performance is limited by the transmission and birefringent coefficient of the available materials. In this paper, a polarization beam combiner based on a reflection metasurface was proposed. The phases of incident beams with orthogonal linear polarizations were individually manipulated by the side lengths of the rectangular silicon pillar. A metasurface polarization beam combiner operating band was designed and fabricated. When the two beams at 4.6 μm with orthogonal linear polarizations were incident on the metasurface at angles of −13.3° and 13.3°, respectively, they were reflected in the 0°-direction. The overall beam combining efficiency was 88.9%. When both of the quantum cascade lasers used in the experiments were in the fundamental transverse Gaussian mode, the measured beam quality factors M² of the combined beam were 1.21 and 1.14 along the fast and slow axes, respectively. Both simulation and experimental results demonstrated that the proposed metasurface was an efficient polarization beam combiner with negligible wavefront distortion. It is a promising alternative to traditional bulk optics for the mid- and long-wave infrared. Full article

Diffractive optical elements (DOEs) are essential components in optical and photonic technologies, motivating the need for rapid mass production with high-precision fabrication methods. Photopolymers are particularly attractive for DOEs production because their optical phase can be modified via both surface and refractive index modulations. In this work, we report the fabrication of DOEs on PVA/AA photopolymers using ultrafast laser direct writing. By combining surface topography measurements with a phase depth model, we extract the surface and bulk phase depth contributions and demonstrate a transition from surface-dominated modulation at 1 kHz to bulk refractive index modification under cumulative conditions at 100 kHz. These outcomes highlight ultrafast laser direct writing as a powerful, rapid and controlled method for the high-quality and rapid fabrication of DOEs. Full article

AlCoCrFeNi high-entropy alloys (HEAs) are promising materials due to their exceptional mechanical properties and thermal stability. This study employs first-principles calculations based on density functional theory (DFT) to investigate the phase stability and electronic properties of AlCoCrFeNi HEA. The atomic size difference (δ) was determined to be 5.44%, while the mixing enthalpy (ΔH_mix) was found to be −14.24 kJ/mol, and the valence electron concentration (VEC) was measured at 7.2, indicating a dual-phase structure consisting of the BCC and B2 phases. The formation energies indicated that the BCC phase exhibits the highest stability under typical conditions. The elastic properties were assessed, revealing Young’s modulus of 250 GPa, a shear modulus of 100 GPa, and a bulk modulus of 169 GPa, which suggest high stiffness. The alloy demonstrated a Poisson’s ratio of 0.25 and a G/B ratio of 0.59, indicating relatively brittle behavior. Microhardness simulations predicted a value of 604 HV0.2, which closely aligns with experimental measurements of 602 HV0.2 at 1300 W laser power, 532 HV0.2 at 1450 W, and 544 HV0.2 at 1600 W. The electronic structure analysis revealed metallic behavior, with the d-orbitals of Co, Fe, and Ni contributing significantly to the electronic states near the Fermi level. These findings offer valuable insights into the phase behavior and mechanical properties of AlCoCrFeNi HEA, which are crucial for the design of high-performance materials suitable for extreme engineering applications. Full article

Titanium-based bulk metallic glasses (BMGs) offer high strength, lower stiffness than Ti-6Al-4V, and superior corrosion resistance, but conventional Ti glass-forming systems often contain toxic Ni, Be, or Cu. This work investigates five novel Ti-based alloys free of these elements—Ti₄₂Zr₃₅Si₅Co_12.5Sn_2.5Ta₃, Ti₄₂Zr₄₀Ta₃Si₁₅, Ti₆₀Nb₁₅Zr₁₀Si₁₅, Ti₃₉Zr₃₂Si₂₉, and Ti_65.5Fe_22.5Si₁₂—synthesized by arc melting and suction casting. Single-track laser remelting using a selective laser melting (SLM) system was performed to simulate additive manufacturing and examine microstructural evolution, cracking behavior, mechanical properties, and cytocompatibility. All alloys solidified into fully crystalline α/β-Ti matrices with Ti/Zr silicides; no amorphous structures were obtained. Laser remelting refined the microstructure but did not induce glass formation, consistent with the known limited glass-forming ability of Cu/Ni/Be-free Ti systems. Cracking was observed at low laser energies but crack density decreased as laser energy increased. Cracks were eliminated above ~0.4 J/mm for most alloys. Ti₄₂Zr₃₅Si₅Co_12.5Sn_2.5Ta₃ exhibited the lowest stiffness (~125 GPa), while Ti₆₀Nb₁₅Zr₁₀Si₁₅ showed the highest due to silicide precipitation. Cytotoxicity tests (ISO 10993-5) confirmed all alloys to be non-toxic, with some extracts even enhancing fibroblast proliferation. This rapid laser-remelting approach enables cost-effective screening of Ti-based glass-forming alloys for additive manufacturing. Ti–Zr–Ta–Si systems demonstrated the most promising properties for further testing using the powder bed method. Full article

Quantum sensing with nitrogen vacancy (NV) defects in diamond enables detection of extremely small changes in temperature, host material strain, and magnetic and electric fields. Action potential detection has previously been demonstrated with cardiac tissue and whole organisms using NV defects in bulk diamond crystals. Nanodiamonds (NDs) with NV defects were previously used as effective fluorescent markers, as they do not bleach under laser illumination like conventional fluorescent dyes. Subcellular-level action potential recording with NDs is yet to be demonstrated. Here, we report our results on the confocal imaging of NDs and the feasibility of optically detected magnetic resonance (ODMR) experiments with Cath.-a-differentiated (CAD) mouse brain cells. 10 nm and 60 nm NDs were shown to diffuse into cells within 30 min with no additional surface modification, as confirmed with confocal imaging. In contrast, 100 nm and 140 nm NDs were observed to remain localized on the cell surface. ND photoluminescence (PL) signals did not bleach over the course of 5 h long imaging studies. ODMR technique was used to detect externally applied millitesla-level magnetic fields with NDs in cell solutions. In summary, NDs were shown to be effective, non-bleaching fluorescent markers in mouse brain cells, with further potential for use in action potential recording at the subcellular level. Full article

Laser slicing has emerged as a promising low-kerf and low-damage technique for SiC wafer fabrication; however, its effects on the crystal integrity, near-surface modification, and charge-transport properties require further clarification. Here, a heavily N-doped 4° off-axis 4H-SiC wafer was sliced using an ultraviolet (UV) picosecond laser, and both laser-irradiated and laser-sliced surfaces were comprehensively characterized. X-ray diffraction and pole figure measurements confirmed that the 4H stacking sequence and macroscopic crystal orientation were preserved after slicing. Raman spectroscopy, including analysis of the folded transverse-optical and longitudinal-optical phonon–plasmon coupled modes, enabled dielectric function fitting and determination of the plasmon frequency, yielding a free-carrier concentration of ~3.1 × 10¹⁸ cm⁻³. Hall measurements provided consistent carrier density, mobility, and resistivity, demonstrating that the laser slicing process did not degrade bulk electrical properties. Multi-scale Atomic Force Microscopy (AFM), Angle-Resolved X-Ray Photoelectron Spectroscopy (ARXPS), Secondary Ion Mass Spectrometry (SIMS), and Transmission Electron Microscopy (TEM)/Selected Area Electron Diffraction (SAED) analyses revealed the formation of a near-surface thin amorphous/polycrystalline modified layer and an oxygen-rich region, with significantly increased roughness and thicker modified layers on the hilly regions of the sliced surface. These results indicate that UV laser slicing maintains the intrinsic crystalline and electrical properties of 4H-SiC while introducing localized nanoscale surface damage that must be minimized by optimizing the slicing parameters and the subsequent surface-finishing processes. Full article

Metal additive manufacturing (AM) offers promising advancements in producing implants with complex geometry for biomedical applications, where accuracy and near-net-shape production are essential. Metal AM by laser powder bed fusion (PBF-LB) is a promising route to produce biodegradable iron implants made of complex lattice structures. However, processing windows for pure iron remain poorly defined. This work focuses on optimizing PBF-LB parameters for pure iron using a design of experiments (DoE) approach on bulk samples of different geometries to evaluate different parameters. Hatch laser power, scanning speed, hatch distance and point distance were varied and their effect on porosity, surface roughness and dimensional accuracy was evaluated. This was followed by the fabrication of rhombitruncated cuboctahedron (RTCO) lattice structures with the best parameters previously defined for the bulk samples. The best parameter set (hatch laser power 180 W, scanning speed 600 mm/s, hatch distance 110 µm and point distance 12 µm, corresponding to a volumetric energy density of 90.9 J/mm³) produced bulk samples with a porosity as low as 0.07% (99.93% density) measured in polished sections. Using these parameters, RTCO lattices with designed relative densities of 10.28%, 35.29% and 65.16% were successfully manufactured with small geometric deviations and good control of strut thickness and relative density. The results of this study define a robust PBF-LB processing window for pure iron and demonstrate the feasibility of producing geometrically controlled, biodegradable iron lattice structures suitable for future load-bearing biomedical applications. Full article

The NELIPS acronym stands for Nano-Enhanced Laser-Induced Plasma Spectroscopy. Within this framework, the temporal variation in the enhanced plasma emissions from pure nanomaterials with respect to corresponding bulk materials was monitored as a function of delay time in the range from 1 to 5–11 μs. Six different pure nanomaterials were employed including silver, zinc, aluminum, titanium, iron, and silicon. Radiation from pulsed Nd: YAG laser at wavelength 1064 nm was used to induce both bulk and pure nanomaterial plasmas under similar experimental conditions. Plasma emissions from both targets were monitored via optical emission spectroscopy technique (OES). The spectral line intensities (Signal-To-Noise ratio S/N) from the pure nanomaterial plasma turns out to decline in a constant logarithmic manner but at a slower rate than that from the corresponding bulk material plasma. Consequently, the measured average enhanced emission from different nanomaterials features an increase in an exponential manner with delay time. This trend of increase was accounted for via mathematical elaboration of enhanced emission based on the measured Signal-To-Noise data. Plasma parameters (electron density and temperature) were precisely measured at each delay time as well. Full article

A novel approach for laser coherent beam combination (CBC) utilizing the self-imaging effect in plasma waveguides is presented in this study, which enables the transmission of ultrashort laser pulses at intensities above the bulk damage threshold of conventional solid optical waveguides. The feasibility of self-imaging-based CBC in plasma waveguides was simulated and verified, demonstrating favorable combining efficiency and beam quality. This work explores the adaptive tuning of waveguide length via dynamic adjustment of plasma density, addressing the critical issue of fabrication tolerances in traditional waveguide systems. With CBC via plasma waveguide, this study offers support for the development of robust, high-power laser systems with enhanced beam quality and operational stability. Full article