Search Results (252)

A high-efficiency extra-cavity Raman generator is demonstrated using a potassium yttrium tungstate (KYW) crystal for the first time, achieving switchable yellow-green laser output at 556 nm and 560 nm. The KYW Raman crystal is single-pass pumped by 532 nm green light, which is obtained by the second-harmonic generation of a 1064 nm flash-lamp-pumped Nd:YAG electro-optic (EO) Q-switched laser. When the incident pump energy at 1064 nm is 156 mJ under a repetition rate of 1 Hz, the maximum output energy reaches 51.3 mJ at 532 nm with a slope efficiency of 41.5%. By adjusting the polarization direction of the 532 nm light, two characteristic Raman shifts of the KYW crystal can be selectively excited at 765 cm⁻¹ and 905 cm⁻¹. Furthermore, the 556 nm and 560 nm visible lasers are generated with the maximum output energies of 11.6 mJ and 16.2 mJ, corresponding to the slope efficiencies of 37.6% and 48.2%, respectively. Compared with the 532 nm pulse width (18.2 ns), an obvious Raman pulse width compression effect occurred (8.2 ns). Full article

Efficient laser cleaning of glazed ceramic tiles requires the ink layer to be removed without damaging the brittle glaze. We investigated the removal of acrylic ink using a 1064 nm, 10 ns Nd:YAG laser operating at 1 Hz. The lens-to-sample working distance L, pulse energy, and pulse number were varied, and the cleaned regions were evaluated by optical microscopy (OM), scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM–EDS), theoretical analysis, and COMSOL simulation. At L = 20 cm, the sample was close to the nominal focal plane, and the high local fluence removed the ink rapidly, but it also produced whitening, depressions, micro-pits, and glaze damage. Increasing L to 25–30 cm enlarged the measured spot diameter, lowered the average fluence, and widened the controllable cleaning range. Two low-damage conditions were identified at L = 30 cm: 30.80 J/cm² with 3 pulses and 41.00 J/cm² with 2 pulses. SEM–EDS showed that cleaning quality cannot be judged from exposed area or carbon content alone; morphology, preservation of the native glaze microstructure, the C/O ratio, and recovery of substrate-related elements must be considered together. Under the stated model assumptions, the calculated local temperature exceeded the acrylic decomposition temperature, and the thermoelastic stress reached tens to hundreds of MPa. These results make thermal decomposition and stress-assisted interfacial separation physically plausible. However, the present data do not separate thermoelastic stress from pressure-wave loading. Likewise, visible air breakdown and non-monotonic cleaning at high pulse energy only suggest possible plasma-related attenuation because plasma density and transmitted laser energy were not measured. The reported combinations should therefore be regarded as a system-specific process window rather than a universal optimum. Full article

Implant-associated infections remain one of the leading causes of failure in orthopaedic and dental implants, necessitating the development of multifunctional surface coatings capable of simultaneously enhancing corrosion resistance, bioactivity, and antibacterial performance. The aim of this study was to investigate how picosecond laser surface treatment modifies the structural, physicochemical, mechanical, electrochemical, bioactive, and antibacterial properties of magnetron-sputtered TiO₂/CuO coatings on Ti6Al4V alloy. Structural characterisation revealed that laser treatment transformed the predominantly amorphous TiO₂ matrix into a more crystalline rutile-containing structure while preserving the CuO phase. The laser surface-treated (LST) surface exhibited increased surface hydroxylation, enhanced wettability, and a slightly higher release of Cu ions. In addition to modifying the surface chemistry, laser treatment improved the mechanical characteristics of the coating, contributing to its overall durability and suitability for biomedical implant environments. Electrochemical impedance spectroscopy demonstrated that both coatings significantly improved the corrosion resistance of Ti6Al4V in simulated body fluid, whereas the laser-treated coating showed superior long-term stability and passive layer evolution. Following immersion, both surfaces promoted the formation of Ca–P-rich hydroxyapatite deposits, indicating favourable bioactivity. Antibacterial testing against Staphylococcus aureus revealed reductions in bacterial viability of 67% and 74% for the AD and LST coatings, respectively. The enhanced antibacterial performance of the laser-treated surface was attributed to the combined effects of increased crystallinity, surface hydroxylation, hydrophilicity, and copper ion release. The novelty of this work lies in demonstrating that picosecond laser post-treatment can simultaneously tailor the crystallinity, surface chemistry, morphology, corrosion resistance, bioactivity, and antibacterial performance of magnetron-sputtered TiO₂/CuO coatings without compromising coating integrity, thereby providing a promising multifunctional surface modification strategy for biomedical implants. Full article

The long-term stability of biodegradable polymer coatings deposited by matrix-assisted pulsed laser evaporation (MAPLE) remains insufficiently understood, particularly under ultraviolet irradiation conditions where photochemical effects may accompany material transfer. In this work, thin films of poly(lactide-co-caprolactone)-block-poly(ethyleneglycol)-block-poly(lactide-co-caprolactone), also known as PLCL-PEG-PLCL, are deposited from chloroform solutions by UV-MAPLE using a nanosecond Nd:YAG laser operating at 266 nm over a wide laser fluence range (0.25–0.9 J/cm²). The effect of laser fluence on the morphological, structural, and chemical evolution of the coatings is investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), focused ion beam scanning electron microscopy (FIB-SEM), and X-ray diffraction (XRD). At low laser fluence, relatively homogeneous coatings are obtained while largely preserving the characteristic functional groups of the triblock copolymer. Increasing the laser fluence progressively induces surface restructuring phenomena, including droplets, wrinkles, and the appearance of highly symmetric faceted structures. These entities develop preferentially in samples deposited at elevated fluence and frequently appear only after prolonged aging under ambient conditions, revealing delayed recrystallization behaviour associated with metastable species generated during the deposition process. EDS analyses reveal localized chlorine enrichment within the faceted structures, while FIB-SEM investigations show porous internal morphologies. XRD confirms that the polymer matrix remains predominantly amorphous. The combined observations suggest that UV-MAPLE deposition from chloroform involves not only physical material transfer but also photochemical processes that promote decomposition, recombination, and delayed crystallization phenomena. A phenomenological model describing the successive stages of surface evolution, aging, and recrystallization is proposed. These results provide new insight into the long-term evolution of laser-deposited biodegradable polymer coatings and highlight the importance of solvent selection and processing conditions in determining their stability. Full article

This work presents and discusses a study of the oxidized patina on copper-based coins. Patina layers were characterized after thermal treatments on various coins and calibration samples using X-ray fluorescence (XRF) spectroscopy, which was employed to measure oxide layer thicknesses. Laser ablation of copper-based samples was carried out with an ns pulsed Nd:YAG laser operating at 1064 nm. The ablation yield was measured based on selected laser parameters and is analyzed in relation to controlled cleaning of different types of copper surfaces, either to remove superficial oxides from artistic or manufactured objects or to remove patina from old coins. As a micro-invasive technique, laser ablation may provide a methodological approach for patina thickness assessment and, in carefully controlled and case-specific situations, for selective surface treatment. Full article

Rare earth element (REE) detection sensitivity with minimal sample damage is exciting. Laser-induced breakdown spectroscopy (LIBS) with a typical methodology is a useful diagnostic tool, but often shows poor REE sensitivity. This study presents the qualitative, quantitative, and classification analysis of REE-bearing ore samples that contain multiple elements from the lanthanoid (Ln) group (e.g., La, Ce, Nd, Sm, and Gd) using the LIBS technique, and the results are compared with those obtained using a magnetic-field-assisted LIBS (MFA-LIBS) system. The LIBS spectrum was recorded using a Nd:YAG Laser with a 532 nm emission wavelength, a 5 ns pulse duration, and a 10 Hz repetition rate. Optical regions exhibiting the strongest emission lines of REEs were identified, followed by MFA-LIBS to improve the qualitative signatures of the elements of interest. MFA-LIBS also assists in confirming signal enhancement for Sm and Gd, which were unidentified with a conventional LIBS setup. Quantitative analysis was performed using a calibration-free and magnetic-field-assisted LIBS (CF-MF-LIBS) method. La, Ce, and Nd concentrations were estimated to be from 1 to 3 wt.%, whereas Sm and Gd were detected within 0.5 wt.%. The results obtained using CF-MF-LIBS were compared with those obtained using the X-ray fluorescence spectroscopy (XRF) technique, showing good agreement between the LIBS/XRF techniques. Further, the limit of detection (LOD) of the REEs using in-house prepared samples was estimated, and the results were compared with those previously reported in the literature. Furthermore, classification analysis of REE ores based on compositional variations was achieved using principal component analysis (PCA). The first two principal components (PCs) with maximum spectral variance, such as PC1~74.5% and PC2~14.5%, were considered for the clustering, and ellipses with 95% confidence using major (x) and minor (y) axes were created to explore outliers. Therefore, the CF-MF-LIBS method in combination with PCA demonstrates a rapid, robust, and effective methodology for the detection, quantification, and classification investigation of REE-bearing ores. Full article

Cutaneous melanoma is an aggressive skin cancer. While laser therapy is established for non-melanoma skin cancers, its role in melanoma remains controversial and largely unsupported by robust clinical evidence. The gold standard for melanoma management remains surgical excision, as it allows for definitive histopathological diagnosis, Breslow thickness measurement, and surgical margin assessment, which are essential for accurate staging. This narrative review analyzed preclinical and clinical studies evaluating various laser modalities, including Nd:YAG, CO₂, pulsed dye, photodynamic therapy (PDT) and photothermal therapy (PTT), for efficacy, recurrence rates, and limitations in cutaneous melanoma management. Nd:YAG laser (1064 nm) showed potential for local control in thin stage I melanomas, reporting a low local recurrence rate of 0–0.7% and favorable 5-year survival in small, non-randomized cohorts. CO₂ laser (10,600 nm) provides effective palliation and local control for in-transit or unresectable metastases, but local recurrence is highly variable, reaching up to 46.7%. Photodynamic therapy showed variable efficacy, although Chlorin e6 achieved complete local regression in a small series of metastases. A critical limitation of laser therapy is the irreversible destruction of tissue, which precludes these vital assessments. Therefore, laser treatment should be cautiously reserved for cases where standard surgery is not feasible, acknowledging that it may interfere with the evaluation of curative outcomes and accurate staging. Laser therapy is a valuable minimally invasive adjunct for local control in selected patients who are poor surgical candidates or require palliative care. Routine use is restricted by the lack of randomized controlled trials. Future studies should prioritize combination strategies with systemic or immunotherapeutic approaches to enhance overall outcomes. Full article

Background: Endoscopic kidney-sparing surgery (eKSS) is increasingly adopted for the management of selected patients with upper tract urothelial carcinoma (UTUC). Laser energy is central to tumor ablation during eKSS; however, multiple laser platforms with distinct physical and thermal properties are currently available, and their comparative oncological and safety profiles remain poorly defined. This systematic review aims to summarize the available evidence on oncological outcomes and perioperative complications associated with laser-based endoscopic treatment of UTUC and to explore potential differences according to laser technology. Methods: A systematic literature search identified 25 eligible studies published between 1997 and 2024, including 1344 patients treated with laser-assisted eKSS. All included studies were non-randomized, predominantly retrospective, and characterized by moderate-to-serious risk of bias. Holmium:YAG, Thulium:YAG (thu:YAG, continuous-wave and pulsed), thulium fiber laser (TFL), Neodimio:YAG (Nd:YAG), diode lasers, and combination platforms were reported. Results: Ipsilateral upper tract recurrence was common across all laser categories, with weighted proportions ranging approximately from 27% to 52% and substantial inter-study heterogeneity. Progression and conversion to radical nephroureterectomy (RNU) were relatively infrequent overall, with numerically weighted proportions observed in thu:YAG-based cohorts. Major complications (Clavien–Dindo ≥ III) were rare across all laser technologies, although a trend toward a higher weighted proportions was observed in Ho:YAG- and Nd:YAG-based series. Minor complications were more frequently reported and highly heterogeneous. Conclusions: Available evidence supporting laser selection in endoscopic kidney-sparing management of UTUC is limited and largely descriptive. Thulium:YAG and TFL platforms seem to demonstrate encouraging trends toward lower progression and conversion to-radical-nephroureterectomy rates; however, these findings are derived from heterogeneous, non-comparative studies with limited follow-up. No standard laser platform can currently be recommended over others based on existing data. Prospective, comparative, and methodologically robust studies are required to determine whether laser technologies confer clinically meaningful advantages in oncological control or safety for UTUC treated with eKSS. Full article

Rosacea is a chronic inflammatory skin disease characterized by erythematous, papular, and pustular lesions. Treatment for rosacea is tailored to the type and severity of lesions and the individual needs of the patient. The primary therapy involves topical and systemic treatments. Laser therapy is also an effective method. This review summarizes current knowledge on the application of pulsed dye lasers (PDLs), potassium titanyl phosphate (KTP) lasers, intense pulsed light (IPL), neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers, carbon dioxide (CO₂) lasers, and erbium-doped yttrium aluminum garnet (Er:YAG) lasers in the treatment of rosacea. Research confirms that the PDL remains the gold standard, demonstrating excellent clinical efficacy. The KTP and IPL lasers provide comparable outcomes, with relatively fewer adverse effects. Due to its greater depth of penetration, the Nd:YAG laser is used to treat lesions in the deeper layers of the skin. In advanced forms of rosacea, such as rhinophyma, ablative lasers, including CO₂ and Er:YAG, are employed. This review summarizes the mechanisms of action, therapeutic applications, and adverse effects associated with the use of various laser types in the management of rosacea. Full article

Basal cell carcinoma (BCC) is the most frequent skin cancer, and surgery remains the treatment of choice, particularly in high-risk subtypes and sites. However, in low-risk cases and in patients where cosmetic outcome is a priority, alternative strategies, including laser therapy, have been proposed. Different laser sources offer potential advantages in terms of minimal invasiveness, healing time, and cosmetic outcome, but their clinical role remains a matter of debate. This narrative review critically analyses the available evidence on the use of lasers in the treatment of basal cell carcinoma, with a focus on ablative lasers, vascular lasers, and laser-assisted photodynamic therapy. Mechanisms of action, main clinical results, limitations, and the emerging contribution of non-invasive imaging for case selection and response monitoring are discussed. Ablative lasers, in particular CO₂, show favourable results in superficial low-risk BCC, while clearance reliability decreases with increasing tumour depth. Vascular lasers may offer short-term control in selected lesions but with limited long-term data. Laser-assisted PDT represents a promising strategy to extend the indication of PDT to selected nodular forms. Overall, the literature is limited by methodological heterogeneity, incomplete stratification, and short follow-ups. Well-designed comparative studies, standardised protocols, and objective controls will be essential to define the real clinical space of laser therapy in basal cell carcinoma. Full article

ZnSe nanoparticles were synthesized via the sustainable laser fragmentation in liquids (LFL) technique using a Nd:YAG laser at 1064 nm. The pulse energy was varied to study its effect on the particle size and vibrational properties. UV–Vis absorption spectra show a blue shift in the absorption edge with a decreasing pulse energy. The sample processed at the lowest pulse energy has the smallest nanoparticles (10.3 nm average), reaches an optical band gap of 2.83 eV, and exhibits a high-energy shoulder attributed to spin–orbit-related transitions. Raman spectra reveal a strong enhancement of the surface phonon mode (231–234 cm⁻¹), where its intensity surpasses that of the longitudinal optical mode, demonstrating the dominant role of surface atoms in the vibrational response. TEM confirms a wide size distribution, i.e., centered at 10.3 ± 6.4 nm, which can account for the simultaneous observation of bulk-like and quantum-confined optical and Raman features. These results show that the pulse energy effectively tunes the nanoparticle size and phonon behavior, positioning LFL as a clean and versatile method for producing ZnSe nanostructures with relevant properties for optoelectronic applications. Full article

This work presents results on laser-induced fabrication of metal and oxide structures on glass substrates. The Laser-Induced Reverse Transfer (LIRT) technique is applied using Zn and Sn, sintered ZnO and SnO₂, and oxide composite targets. The processing is performed by nanosecond pulses of a Nd:YAG laser system operated at wavelength of 1064 nm. Detailed analyses of the deposited material morphology, composition and structure are presented, as the role of the processing conditions is revealed. It is found that at the applied conditions of using up to five laser pulses, the deposited material is composed of a nanostructured film covered in microsized nanoparticle clusters or droplets. The use of metal targets leads to formation of structures composed of metal and oxide phases. The adhesion test shows that part of the deposited material is stably adhered to the substrate surface. It is demonstrated that the deposited materials can be used as resistive gas sensors with sensitivity to NH₃, CO, ethanol, acetone and N₂O, at concentrations of 30 ppm. The ability of the method to deposit composite structures that consist of a mixture of both investigated oxides is also demonstrated. Full article

We demonstrate that pulsed laser annealing induces plasmonic gold nanoparticles in ZnO thin films, monitored in real-time via pulse-by-pulse spectroscopy. Initially embedded gold nanoparticles (smaller than 5 nm) in sputtered ZnO films were annealed using 532 nm pulses from a Q-switched Nd:YAG laser while monitoring transmission spectra in situ. A plasmonic resonance dip emerged after ~100 pulses in the 530–550 nm region, progressively deepening with continued exposure. Remarkably, different incident energies converged to a thermodynamically stable optical state centered near 555 nm, indicating robust nanoparticle configurations. After several hundred laser shots, the process stabilized, producing larger nanoparticles (40–200 nm diameter) with significant surface protrusion. SEM analysis confirmed substantial gold nanoparticle growth. Theoretical modeling supports these observations, correlating spectral evolution with particle size and embedding depth. The protruding gold nanoparticles can be functionalized to detect specific biomolecules, offering significant advantages for biosensing applications. This approach offers superior spatial selectivity and real-time process monitoring compared to conventional thermal annealing, with potential for optimizing uniform nanoparticle distributions with pronounced plasmonic resonances for biosensing applications. Full article

Skin scars represent a complex therapeutic challenge, with significant functional, aesthetic, and psychological implications. Despite advances in laser therapy, monotherapy has significant limitations, particularly for patients with complex scars with atrophic, hypertrophic, vascular, and pigmentary components. The combined use of multiple laser sources, in sequential or simultaneous mode, allows for the selective targeting of specific tissue components and improves clinical efficacy while maintaining a good safety profile. This narrative review critically analyses the available evidence on combination therapies for atrophic, hypertrophic, keloid, and post-surgical and burn scars. Protocols combining ablative lasers (CO₂, Er:YAG), non-ablative lasers (1540–1550 nm), vascular lasers (PDL, Nd:YAG) and intense pulsed light (IPL) are reported. Possible integrations with adjuvant techniques, such as radiofrequency, platelet-rich plasma (PRP), and laser-assisted drug delivery, are also mentioned as areas for future development. The available data suggest a promising role for multimodal strategies, but the literature remains limited by small cohorts, heterogeneous protocols, and short follow-up periods. Although adverse events are generally mild and transient, typically involving erythema, oedema, or temporary dyschromia, an awareness of safety considerations remains essential, particularly in higher phototypes and when using ablative modalities. Further prospective and multicentre studies are needed to define standardised protocols and consolidate the role of combination therapies in the management of scars. Full article

Nanosecond-pulsed Nd:YAG laser ablation was investigated as a method for removing Al Ti-based hard coatings deposited on WC–Co hardmetal inserts. Systematic variation in laser parameters identified conditions for complete coating removal while preserving substrate integrity. The laser was operated at 532 nm, under a range of fluences (0.1–11.7 J/cm²), pulse delays (20–180 µs), and pulse numbers (1–300). LIBS qualitative monitoring enabled precise ablation progress by identifying Ti, Al, and O layers, and later the detection of Co and W signals. Scanning electron microscopy (SEM/EDS) and optical profilometry confirmed that 5–10 pulses at intermediate delays (60–80 µs, 4.8–7.1 J/cm²) provided complete removal of ~18 µm-thick coatings while maintaining substrate integrity. In contrast, higher energies and excessive pulses caused localized melting and surface irregularities. These results demonstrate that Nd:YAG laser ablation, especially when coupled with LIBS, offers a precise, fast, and environmentally alternative to conventional chemical stripping methods for the refurbishment and recycling of cutting tools. Full article