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Excessive emissions of heavy metals not only cause environmental pollution but also pose a direct threat to human health. Therefore, rapid and accurate detection of heavy metals in the environment is of great significance. Herein, we propose a method based on laser-induced breakdown spectroscopy (LIBS) combined with filter paper modified with bovine serum albumin-protected gold nanoclusters (LIBS-FP-AuNCs) for the rapid and sensitive detection of Cr 3+ and Mn 2+ . The filter paper modified with AuNCs was used to selectively enrich Cr 3+ and Mn 2+ . Combined with the multi-element detection capability of LIBS, this method achieved the simultaneous rapid detection of Cr 3+ and Mn 2+ . Both elements showed linear ranges for concentrations of 10-1000 μg L -1 , with limits of detection of 7.5 and 9.0 μg L -1 for Cr 3+ and Mn 2+ , respectively. This method was successfully applied to the determination of Cr 3+ and Mn 2+ in real water samples, with satisfactory recoveries ranging from 94.6% to 105.1%. This method has potential application in the analysis of heavy metal pollution.

This work presents the results of paper laser processing. It begins with the selection and examination of the processing parameters, then an examination of the properties of the modified papers and examples of applications of the developed modification method. The properties of laser-modified paper were studied using reflectance spectrophotometry to examine the colour aspects of the modified papers, scanning electron microscopy (SEM) and confocal microscopy for a morphological analysis, and Raman spectroscopy to analyse the papers under the influence of laser light. The influence of laser processing on the wettability of paper and the evenness of unprinted and printed paper was also investigated. The knowledge gained on paper surface modification with laser light was used to propose several applications, such as methods of marking, tactile detection, the controlled removal of optical brightener, ink, and metallised coatings from paper packaging, highlighting the design and aesthetics of paper. The developed laser-assisted method shows a promising, ecological approach to the design of many value-added paper products. [ABSTRACT FROM AUTHOR]

This bibliometric study analyzed the 100 most-cited papers about the use of lasers and their modalities in dentistry. A search strategy was created using specific keywords related to the topic. A comprehensive search was then conducted in the Web of Science Core Collection (WoS-CC) database up to July 2021. Papers that addressed the application of any type of laser and its modalities in dentistry were included. Each paper was cross-matched with the number of citations on Scopus and Google Scholar. The following data were extracted from papers: title, number of citations, authorship, country, year of publication, journal, study design, subject, laser type, and oral health outcomes. The VOSviewer software was used to generate bibliometric networks. The total number of citations ranged from 120 to 4,124 and 23 papers received more than 200 citations. Papers were published from 1964 to 2015. Most papers were from Europe (42%) and Anglo-Saxon America (27%). The USA was the country with more top 100 papers (25%). Papers were published mainly in Lasers in Surgery and Medicine (15%) and Lasers in Medical Science (7%). VOSviewer maps demonstrated the existence of national and international research collaborations among institutions and authors. Most studies had a laboratory design (57%) and were about restorative dentistry (32%) and periodontics (21%). This bibliometric study of the top 100 most-cited papers on lasers in dentistry allowed a quantitative and qualitative analysis of this very promising research field, revealing a net of collaboration and the importance of this topic in dentistry. [ABSTRACT FROM AUTHOR]

Immunoassay is one of the most important clinical techniques for disease/pathological diagnosis. Mass spectrometry (MS) has been a popular and powerful readout technique for immunoassays, generating the mass spectrometric immunoassays (MSIAs) with unbeatable channels for multiplexed detection. The sensitivity of MSIAs has been greatly improved with the development of mass labels from element labels to small-molecular labels. MSIAs are also expended from the representative element MS-based methods to the laser-based organic MS and latest ambient MS, improving in both technology and methodology. Various MSIAs present high potential for clinical applications, including the biomarker screening, the immunohistochemistry, and the advanced single-cell analysis. Here, we give an overall review of the development of MSIAs in recent years, highlighting the latest improvement of mass labels and MS techniques for clinical immunoassays., (© 2022. Springer-Verlag GmbH Germany, part of Springer Nature.)

In this work we suggest a novel paradigm of social laser (solaser), which can explain such Internet inspired social phenomena as echo chambers, reinforcement and growth of information cascades, enhancement of social actions under strong mass media operation. The solaser is based on a well-known in quantum physics laser model of coherent amplification of the optical field. Social networks are at the core of the solaser model; we define them by means of a network model possessing power-law degree distribution. In the solaser the network environment plays the same role as the gain medium has in a physical laser device. We consider social atoms as decision making agents (humans or even chat bots), which possess two (mental) states and occupy the nodes of a network. The solaser establishes communication between the agents as absorption and spontaneous or stimulated emission of socially actual information within echo chambers, which mimic an optical resonator of a convenient (physical) laser. We have demonstrated that social lasing represents the second order nonequilibrium phase transition, which evokes the release of coherent socially stimulated information field represented with the order parameter. The solaser implies the formation of macroscopic social polarization and results in a huge social impact, which is realized by viral information cascades occurring in the presence of population imbalance (social bias). We have shown that decision making agents follow an adiabatically time dependent mass media pump, which acts in the network community reproducing various reliable scenarios for information cascade evolution. We have also shown that in contrast to physical lasers, due to node degree peculiarities, the coupling strength of decision making agents with the network may be enhanced [Formula: see text] times. It leads to a large increase of speed, at which a viral message spreads through a social media. In this case, the mass media pump supports additional reinforcement and acceleration of cascade growth. We have revealed that the solaser model in some approximations possesses clear links with familiar Ising and SIS (susceptible-infected-susceptible) models typically used for evaluating a social impact and information growth, respectively. However, the solaser paradigm can serve as a new platform for modelling temporal social events, which originate from "microscopic" (quantum-like) processes occurring in the society. Our findings open new perspectives for interdisciplinary studies of distributed intelligence agents behavior associated with information exchange and social impact., (© 2022. The Author(s).)

In the world of terahertz bands, terahertz beam deflection has gradually attracted substantial attention, due to its great significance in wireless communications, high-resolution imaging and radar applications. In this paper, a low-reflection and fast-fabricated terahertz beam deflection device has been realized by utilizing graphene oxide paper. Using laser direct writing technology, graphene oxide has been patterned as a specific sample. The thickness of the graphene oxide-based terahertz devices is around 15–20 μm, and the processing takes only a few seconds. The experimental results show that the beam from this device can achieve 5.7° and 10.2° deflection at 340 GHz, while the reflection is 10%, which is only 1/5 of that of existing conventional devices. The proposed device with excellent performance can be quickly manufactured and applied in the fields of terahertz imaging, communication, and perception, enabling the application of terahertz technology. [ABSTRACT FROM AUTHOR]

In this work, fabrication of frequency selective surface filters by coating paper with silver ink and subsequent laser etching the frequency filter pattern has been investigated. Three filter structures consisting of a combination of square and ring patches operating at 102, 113, and 126 GHz and with corresponding signal attenuation of −15.2, −15.4, and −14.5 dB were fabricated and simulated; −5 dB bandwidths were following, 93.3–112.2 GHz, 101.9–121.1 GHz, and 112.7–132.3, respectively. Also, the proposed screen printing with assistive laser etching could be used to reduce the number of used screens. Furthermore, paper based fabrication using a biodegradable ink could be an alternative fabrication process in future electronic manufacturing. [ABSTRACT FROM AUTHOR]

In a long-distance wireless power transmission system with a non-uniform distribution of laser irradiation, it will significantly reduce the output power of the photovoltaic array, resulting in a large amount of power loss in the system and a decrease in conversion efficiency. This paper proposes an efficient and reliable optimal circuit connection algorithm for the 5 × 5 scale photovoltaic array. Under the laser illumination of 300 W, a 20 m wireless power transmission experiment was performed on four 5 × 5 scale photovoltaic arrays. The results show a 56.49% increase in the maximum output power of the 5 × 5 scale photovoltaic array. [ABSTRACT FROM AUTHOR]

In this paper, the growth of transverse-longitudinal coupled electromagnetic modes in the interaction of high-intensity lasers with dense plasma investigated. Using kinetic theory and solving the scattering relationship for the Vlasov-Maxwell system, the collision effects on the growth of the electromagnetic mode are studied. The anisotropic distribution function considers the effects of body stress due to laser ponderomotive force and plasma density gradient. The results show that a 99% reduction in frequency in the beam path in dense plasma leads to an 88% increase in unstable modes’ growth rate. Increasing the density prevents immediate cessation and enhances the growth of unstable modes. Increasing the density gradient by 99%, the instability rate maximum will increase by 88%. Overall, this paper provides insights into the effects of collision and anisotropic distribution function on the growth of transverse-longitudinal coupled electromagnetic modes in dense plasma. Overall, this paper provides insights into the interplay between various phenomena such as body stress, collision, and electromagnetic modes in dense plasma. [ABSTRACT FROM AUTHOR]

Pavement adhesion plays a crucial role in driving safety, while traditional test methods exhibit some limitations. To improve the efficiency and accuracy of asphalt pavement texture characterization and adhesion assessments, this paper uses three-dimensional (3D) laser technology to detect the continuous point cloud data of road surface and reconstruct the 3D topography of pavement texture. On this basis, a volume parameter Volume of peak materials (Vmp) is innovatively proposed to comprehensively characterize the 3D spatial characteristics of road surface texture. The correlation analysis between the proposed Vmp and the traditional adhesion evaluation index Transversal Adhesion Coefficient (CAT) is conducted, and then refined graded adhesion prediction models based on the proposed Vmp are proposed. Results show that the proposed volume parameter Vmp can reliably and accurately characterize the asphalt pavement texture by considering more structural properties of the road surface texture. According to the research findings of this paper, it is feasible to achieve rapid and correct assessment of asphalt pavement adhesion using 3D laser detection technology by comprehensively considering the 3D characteristics of the road surface texture. [ABSTRACT FROM AUTHOR]

This paper introduces an autonomous robot designed for in-pipe structural health monitoring of oil/gas pipelines. This system employs a 3D Optical Laser Scanning Technical Vision System (TVS) to continuously scan the internal surface of the pipeline. This paper elaborates on the mathematical methodology of 3D laser surface scanning based on dynamic triangulation. This paper presents the mathematical framework governing the combined kinematics of the Mobile Robot (MR) and TVS. It discusses the custom design of the MR, adjusting it to use of robustized mathematics, and incorporating a laser scanner produced using a 3D printer. Both experimental and theoretical approaches are utilized to illustrate the formation of point clouds during surface scanning. This paper details the application of the simple and robust mathematical algorithm RANSAC for the preliminary processing of the measured point clouds. Furthermore, it contributes two distinct and simplified criteria for detecting defects in pipelines, specifically tailored for computer processing. In conclusion, this paper assesses the effectiveness of the proposed mathematical and physical method through experimental tests conducted under varying light conditions. [ABSTRACT FROM AUTHOR]

Receiving inspection plays a crucial role in ensuring construction quality after the completion of engineering projects. Traditional inspection measurement methods, such as manual observation means and optical equipment measurement methods, have limitations in terms of the number of measurement sites and the range of measurements. These traditional methods fail to provide accurate curve parameters and continuous spatial morphology information for large-span curved bridge structures. This paper proposes a reverse model measurement method to address this issue. The reverse model is built based on point cloud data acquired by 3D laser scanning technology. Finally, take the Taizicheng No. 1 Bridge as an example, the validity of the proposed method is verified. [ABSTRACT FROM AUTHOR]

In the following paper, the numerical analysis of thermal processes occurring in biological tissue with uncertain parameters is presented. The heat transfer model is based on the Pennes equation, where interval heat sources are introduced. The model is assumed to be transient and one-dimensional. Additionally, analysed tissue is exposed to laser irradiation, and the internal heat sources resulting from laser irradiation based on the Beer law are taken into account. Moreover, the perfusion rate and the effective scattering coefficient are treated as variables dependent on tissue damage. For numerical calculations, the interval version of the Finite Pointset Method has been used. All calculations are performed due to the direct interval arithmetic rules. The paper is concluded by presenting the obtained results. [ABSTRACT FROM AUTHOR]

Based on the laser flash method, the selection of experimental parameters on the accuracy of measurement results for measuring thermal diffusivity is investigated in this paper. High purity graphite is employed as the experimental material. Three experimental parameters are taken into consideration, including specimen thickness, laser pulse power, and laser pulse width. Firstly, the principle of the laser flash method is introduced. Then, a numerical simulation model is established and independence tests are performed. In order to investigate the impact of different experimental parameters to the precision of the measurement results using the laser flash method, six thicknesses of the specimens, five laser pulse powers, and five laser pulse widths are selected for numerical simulation and LFA 427 measurement experiments. Finally, an orthogonal design method with three-factor and three-level is constructed to investigate the influence degree of these three factors on the measurement results. It is found that the laser pulse width has the most significant influence, while the laser pulse power has the least impact. For high purity graphite specimens, it is required to choose a thicker specimen, a lower laser pulse power, and a smaller laser pulse width to ensure better measurement accuracy. [ABSTRACT FROM AUTHOR]

This paper describes and discusses the results of scientific experiences of the physical and mechanical methods used to control and inhibit the growth of lichens and biofilms that grow on indoor and outdoor historical stone artworks. It provides an extensive selection and examination of international papers published in the last two decades on the issue. The great advantage of physical and mechanical methods lies in the lack of potential risks associated with the irreversible application of microbicides. Indeed, they do not introduce any harmful chemicals to humans, to the environment, or to heritage objects. This review focuses on the application of (i) electromagnetic radiation, (ii) high temperatures, (iii) lasers, and (iv) mechanical tools, and includes the main achievements, limitations, and potential applications of the examined studies. [ABSTRACT FROM AUTHOR]

This article provides an overview of laser surface engineering in the field of tribology, which focuses on friction, wear, and lubrication between surfaces in motion. It introduces a special issue on laser surface engineering for tribology, which includes thirteen papers covering topics such as laser cladding, surface texturing, and additive manufacturing. Each paper explores different aspects of laser surface engineering and offers insights for future research and development in the field. The article discusses various research contributions, including the impact of preheating temperatures on laser-clad coatings, the use of laser-assisted surface texturing to reduce friction and wear, and the proposal of a nitride layer to resist tribocorrosion. The findings contribute to improving the wear and corrosion resistance of materials through laser surface engineering. The article concludes by suggesting future research directions and emphasizing the importance of tailoring laser surface engineering approaches to meet industry-specific requirements. [Extracted from the article]

Proper customization in size and shape is essential in implantable bioelectronics for stable bio-signal recording. Over the past decades, many researchers have heavily relied on conventional photolithography processes to fabricate implantable bioelectronics. Therefore, they could not avoid the critical limitation of high cost and complex processing steps to optimize bioelectronic devices for target organs with various sizes and shapes. Here, we propose rapid prototyping using all laser processes to fabricate customized bioelectronics. PEDOT:PSS is selectively irradiated by an ultraviolet (UV) pulse laser to form wet-stable conductive hydrogels that can softly interact with biological tissues (50 μm line width). The encapsulation layer is selectively patterned using the same laser source by UV-curing polymer networks (110 μm line width). For high stretchability (over 100%), mesh structures are made by the selective laser cutting process. Our rapid prototyping strategy minimizes the use of high-cost equipment, using only a single UV laser source to process the electrodes, encapsulation, and substrates that constitute bioelectronics without a photomask, enabling the prototyping stretchable microelectrode array with an area of 1 cm 2 less than 10 min. We fabricated an optimized stretchable microelectrode array with low impedances (∼1.1 kΩ at 1 kHz) that can effectively record rat's cardiac signals with various health states., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Polyamide 12 (PA12) is vastly utilized in many additive manufacturing methods, such as Selective Laser Sintering (SLS), and a better understanding of its mechanical behaviors promotes available knowledge on the behaviors of 3D-printed parts made from this polymer. In this paper, SLS-produced standard tensile specimens are studied under monotonic and cyclic tension tests, as well as stress relaxation experiments, and the obtained force-displacement responses are shown to be consistent with a hyper-viscoelastic material model. This finding is also observed in typical pantographic structures produced by the same manufacturing parameters. To propose a constitutive model for predicting these behaviors, the convolution integral of a strain-dependent function and a time-dependent function is developed where the material parameters are determined with the use of both short-term and long-term responses of the specimens. Numerical results of the presented model for standard test specimens are shown to be in good agreements with the experimental ones under various loading conditions. To prove the capabilities of the proposed model in studying any SLS-produced part, finite element implementation of the constitutive equations is shown to provide numerical results in agreement with the empirical findings for tensile loading of the 3D-printed pantographic structure., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Kadkhodaei et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Alpha-fetoprotein (AFP), commonly employed for early diagnosis of liver cancer, serves as a biomarker for cancer screening and diagnosis. Combining the high sensitivity and specificity of fluorescence immunoassay (FIA), developing a low-cost and efficient immunoassay system for AFP detection holds significant importance in disease diagnosis. In this work, we developed a miniaturized oblique laser-induced fluorescence (LIF) immunoassay system, coupled with a microfluidic PMMA/paper hybrid chip, for rapid detection of AFP. The system employed an avalanche photodiode (APD) as the detector, and implemented multi-level filtering in the excitation light channel using the dichroic mirror and optical trap. At first, we employed the Savitzky-Golay filter and baseline off-set elimination methods to denoise and normalize the original data. Then the cutoff frequency of the low-pass filter and the reverse voltage of the APD were optimized to enhance the detection sensitivity of the system. Furthermore, the effect of laser power on the fluorescence excitation efficiency was investigated, and the sampling time during the scanning process was optimized. Finally, a four-parameter logistic (4PL) model was utilized to establish the concentration-response equation for AFP. The system was capable of detecting concentrations of AFP standard solution within the range of 1-500 ng/mL, with a detection limit of 0.8 ng/mL. The entire immunoassay process could be completed within 15 min. It has an excellent potential for applications in low-cost portable diagnostic instruments for the rapid detection of biomarkers., (© 2024. The Author(s), under exclusive licence to The Japan Society for Analytical Chemistry.)

Herein, we report a multifaceted nanoformulation, developed by binding thionine acetate (TA) in silica matrix to form TA loaded silica nanoparticles (STA Nps), which were characterized using various physicochemical techniques. STA NPs were spherical shaped having size 40-50 nm and exhibited good heating efficiency, improved photostability and singlet oxygen production rate than TA alone. In PDT experiment, the rate of degradation for ABDMA was enhanced from 0.1367 min -1 for TA alone to 0.1774 min -1 for STA Nps, depicting an increase in the reactive oxygen species (ROS) generation ability of STA Nps. Further, the cytotoxicity of STA Nps was investigated by carrying out the biophysical studies with Calf thymus DNA (Ct-DNA) and Human Serum Albumin (HSA). The results indicated that the binding of STA Nps to Ct-DNA causes alterations in the double helix structure of DNA and as a result, STA Nps can impart chemotherapeutic effects via targeting DNA. STA Nps showed good binding affinity with HSA without compromising the structure of HSA, which is important for STA Nps sustainable biodistribution and pharmacokinetics. Based on this study, it is suggested that because of the synergistic effect of chemo and phototherapy, STA Nps can be extensively utilized as potential candidates for treating cancer., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Macroscopic 3D graphene has become a significant topic for satisfying the continuously upgraded smart structures and devices. Compared with liquid assembling and catalytic templating methods, laser‐induced graphene (LIG) is showing facile and scalable advantages but still faces limited sizes and geometries by using template induction or on‐site lay‐up strategies. In this work, a new LIG protocol is developed for facile stacking and shaping 3D LIG macrostructures by laminating layers of LIG papers (LIGPs) with combined resin infiltration and hot pressing. Specifically, the constructed 3D LIGP composites (LIGP‐C) are compatible with large area, high thickness, and customizable flat or curved shapes. Additionally, systematic research is explored for investigating critical processing parameters on tuning its multifunctional properties. As the laminated layers are stacked from 1 to 10, it is discovered that piezoresistivity (i.e., gauge factor) of LIGP‐C dramatically reflects an ≈3900% improvement from 0.39 to 15.7 while mechanical and electrical properties maintain simultaneously at the highest levels, attributed to the formation of densely packed fusion layers. Along with excellent durability for resisting multiple harsh environments, a sensor‐array system with 5 × 5 LIGP‐C elements is finally demonstrated on fiber‐reinforced polymeric composites for accurate strain mapping. [ABSTRACT FROM AUTHOR]

A 1083 nm laser, corresponding to a characteristic spectral line of 3He 23S1-23P, is the core light source for spin-exchange optical pumping-free technology, and thus has important developmental significance. In this paper, precise wavelength 1083.34 nm semiconductor lasers with 285 mW output power, −144.73 dBc/Hz RIN noise and 30.9952 kHz linewidth have been successfully achieved via reasonable chips design, high-quality epitaxial growth process and ultra-low reflectivity coating fabrication. All the results show the highest output power and ultra-narrow linewidth of the single-frequency 1083 nm DFB semiconductor laser achieved in this paper, which can fully satisfy the requirement of quantum magnetometers. [ABSTRACT FROM AUTHOR]

In order to improve the wavefront reconstruction accuracy of a large-aperture laser, this paper proposed an adaptive window preprocessing algorithm based on the threshold center of gravity method (AW-TCoG). The effects of median filtering and mean filtering on spot image processing and wavefront reconstruction accuracy are simulated and analyzed. The results show that the mean filtering method has a better effect on noise elimination and can further improve the accuracy of wavefront reconstruction. In addition, the centroid detection errors of large-aperture laser wavefront reconstruction through the center of gravity (CoG), the threshold center of gravity (T-CoG), and the Windowing method were studied. The analysis shows that, due to the influence of noise, the wavefront reconstruction accuracy is poor when the CoG and Windowing methods are used to calculate centroid parameters, while the wavefront reconstruction accuracy of the threshold centroid method is better and can reach 0.2λ. When using the AW-TCoG proposed in this paper, the wavefront reconstruction accuracy can be maintained within 0.1λ for different incident wavefront RMS values and spot images with different signal-to-noise ratio (SNR) levels. Compared with the traditional threshold centroid method, the wavefront reconstruction accuracy of this method is significantly improved. [ABSTRACT FROM AUTHOR]

With the rapid development of Lidar technology, the use of Lidar for underwater terrain detection has become feasible. There is still a challenge in the process of signal resolution: the underwater laser echo signal is different to propagating in the air, and it is easy to produce weak waves and superimposed waves. However, existing waveform decomposition methods are not effective in processing these waveform signals, and the underwater waveform signal cannot be correctly decomposed, resulting in subsequent data-processing errors. To address these issues, this study used a drone equipped with a 532 nm laser to detect a pond as the study background. This paper proposes an improved inflection point selection decomposition method to estimate the parameter. By comparing it with other decomposition methods, we found that the RMSE is 2.544 and R2 is 0.995975, which is more stable and accurate. After estimating the parameters, this study used oscillating particle swarm optimization (OPSO) and the Levenberg–Marquardt algorithm (LM) to optimize the estimated parameters; the final results show that the method in this paper is closer to the original waveform. In order to verify the processing effect of the method on complex waveform, this paper decomposes and optimizes the simulated complex waveforms; the final RMSE is 0.0016, R2 is 1, and the Gaussian component after decomposition can fully represent the original waveform. This method is better than other decomposition methods in complex waveform decomposition, especially regarding weak waves and superimposed waves. [ABSTRACT FROM AUTHOR]

Autonomous technologies are increasingly used in various areas of science. The use of unmanned vehicles for hydrographic surveys in shallow coastal areas requires accurate estimation of shoreline position. This is a nontrivial task, which can be performed using a wide range of sensors and methods. The aim of the publication is to review shoreline extraction methods based solely on data from aerial laser scanning (ALS). This narrative review discusses and critically analyses seven publications drawn up in the last ten years. The discussed papers employed nine different shoreline extraction methods based on aerial light detection and ranging (LiDAR) data. It should be noted that unambiguous evaluation of shoreline extraction methods is difficult or impossible. This is because not all of the methods reported achieved accuracy, the methods were assessed on different datasets, the measurements were conducted using different devices, the water areas differed in geometrical and optical properties, the shorelines had different geometries, and the extent of anthropogenic transformation. The methods proposed by the authors were compared with a wide range of reference methods. [ABSTRACT FROM AUTHOR]

In the field of inter-satellite laser communication, achieving high-quality communication and compensating for the Doppler frequency shift caused by relative motion necessitate lasers with narrow linewidths, low phase noise, and the ability to achieve mode-hop-free tuning within a specific range. To this end, this paper investigates a novel external cavity diode laser (ECDL) with a frequency-selective F-P etalon structure, leveraging the external cavity F-P etalon structure in conjunction with an auxiliary filter to achieve single longitudinal mode selection. The laser undergoes linewidth testing using a delayed self-heterodyne beating method, followed by the testing of its phase noise and frequency noise characteristics using a noise analyzer, yielding beat spectra and noise power spectral density profiles. Furthermore, the paper introduces an innovative bidirectional temperature-scanning laser method to achieve optimal laser-operating point selection and mode-hop-free tuning. The experimental results showcase that the single longitudinal mode spectral side-mode suppression ratio (SMSR) is around 70 dB, and the output power exceeds 10 mW. Enhancing the precision of the F-P etalon leads to a more pronounced suppression of low-frequency phase noise, reducing the Lorentzian linewidth from the initial 10 kHz level to a remarkable 5 kHz level. The bidirectional temperature-scanning laser method not only allows for the selection of the optimal operating point but also enables mode-hop-free tuning within 160 pm. [ABSTRACT FROM AUTHOR]

This paper presents a novel approach—an efficient closed-form approximation iterative fitting algorithm based on laser absorption spectra. Through this closed-form approximation iterative fitting, key parameters such as peak value, spectral line width, and normalized signal area serve as indicators for iteration completion, improving the speed without compromising accuracy. Furthermore, it employs the spectral signal of n cycles as a window for further processing, minimizing external interference. The results show that the proposed method averages 9.75 iterations, while the Levenberg–Marquardt fitting method averages 60.17 iterations. The average iteration time for the proposed method is 588.83 ms, a substantial 81.7% reduction compared to the 3210.5 ms required by the Levenberg–Marquardt fitting. These results decisively demonstrate the efficacy of the proposed method in reducing iteration time and enhancing measurement precision. [ABSTRACT FROM AUTHOR]

To summarise research studies on scar laser therapy since the 21st century using bibliometric methods, and to speculate on the possible development in the future. The literature about scar laser therapy in Web of Science database was searched. CiteSpace and VOSviewer were used to analyse main countries, institutions, journals，subject hotspots and trends, etc. A total of 884 papers have been published since the 21st century. These publications were written by 653 authors from 515 institutions in 58 countries. The United States published 287 papers in this field and ranks first. Laser in Surgery and Medicine is the most widely published journal, with Shumaker as the core author. The main keyword clustering includes terms such as combination therapy, wound healing, fractional photothermolysis, experience, scar formation, etc. CiteSpace and VOSviewer were used to sort out and summarise the countries, institutions, authors, journals, research hotspots and frontier topics of related literature about scar laser therapy since the 21st century. The current situation of its application and basic scientific research in clinical treatments were summarised briefly. This provides a new idea for the development and research of scar laser therapy in the future. [ABSTRACT FROM AUTHOR]

The paper presents the concept of operation and methods of using laser trackers in robotics. So far, a small amount of research on software for sharing and exchanging data with trackers has been done. As a result of the identified demand, a proprietary application for communication between the laser tracker and robots, as well as other software, was developed. The developed solution is based on the software development kit (SDK) provided by Leica and the Python language. The structure and functioning of the developed software were described in detail. The software meets the goals set at the beginning of the design process regarding online communication with the tracker and using the universal, popular TCP/IP standard. The functioning of the developed software was shown in the paper in a few examples related to manipulating robots and mobile robots. The capabilities of the developed software were described, as well as the planned work on its development. [ABSTRACT FROM AUTHOR]

Whole milk powder and skimmed milk powder are suitable for different groups of people due to their differences in composition. Therefore, a rapid classification method for whole milk powder and skimmed milk powder is urgently needed. In this paper, a novel strategy based on laser-induced breakdown spectroscopy (LIBS) and feature processing methods combined with logistic regression (LR) was constructed for the classification of milk powder. A LR classification model based on mini-batch gradient descent (MGD) was employed first. As indicated by the research results, the accuracy of the MGD-LR model for the milk powder samples in the test set is 96.33% and the modeling time is 33.07 s. The modeling efficiency is low and needs to be improved. Principal components analysis (PCA) and mutual information (MI) were used as feature processing methods to reduce the high dimensional LIBS data into fewer features for improving the modeling efficiency of the classification model. The research results indicate that the accuracy of the PCA-MGD-LR model and the MI-MGD-LR model for the test set of milk powder samples was 99.33% and 99.67%, respectively. Compared with MGD-LR model, the modeling efficiency of PCA-MGD-LR and MI-MGD-LR models has increased by 89.7% and 74.8%, respectively. The results fully demonstrate the feasibility of rapid milk powder classification based on LIBS and feature processing methods combined with LR, and it will provide a new technology for the identification and classification of milk powder., (© 2023. The Author(s), under exclusive licence to The Japan Society for Analytical Chemistry.)

Laser powder bed fusion (L-PBF) involves the coupling of multiple physical fields at different scales. Capturing the dynamic flow and thermal behavior of the melt pool during the L-PBF process through experimentation and predicting its quality is challenging, thus numerical simulation becomes a valuable method. The simulation results enable the prediction and assessment of the impact of material and process parameter changes on the quality of the final product. This paper reviews the methods for selecting appropriate models, performing simulation calculations, and analyzing the results. This paper makes several noteworthy contributions. It provides a comprehensive summary of the physical model, heat loss model, required heat source for simulations, and stresses generated within the melt pool. Furthermore, it explores the practical applications of L-PBF melt pool simulations, especially in defect analysis and the fabrication of complex structures. Finally, it concludes with an insightful analysis of the current trends in L-PBF simulations and outlines potential research directions to advance the development of melt pool simulations. [ABSTRACT FROM AUTHOR]

With the advancing energy transition, icing is a growing problem in the wind turbine sector. The development of systems to detect and mitigate icing makes it necessary to understand its basic behavior and characteristics. This paper proposes a method for the continuous and full-field measurement of the icing process of rotating blades, using a single line laser profile scanner. Inside of a climate chamber, a rotor is driven by a motor, while a system of nozzles provides a fine water dust, which leads to ice accumulating on simple NACA blades, which in turn is measured by a triangulation laser. The measurement data are cleared from outliers and presented as a surface in 3D space. An alpha shape is used to reconstruct and extract the volume of the ice between a reference and a measurement surface, using the corresponding Matlab function. Appropriate input parameters for the function and offsetting of the reference surface to improve the results are compared and discussed. The resulting system is able to detect small changes in the ice layer thickness in the sub-millimeter range. [ABSTRACT FROM AUTHOR]

Introduction: The conventional 3-D point cloud-based deformation analysis methods, such as the shortest distance (SD), cloud-to-cloud (C2C), and multiscale model-to-model cloud comparison (M3C2), essentially regard the closest distance between two periods of point cloud data as the deformation, rather than the true position of the same point in 3-D space before and after deformation. Methods: This paper proposes a method based on the ICP algorithm to calculate the differences between the chunked multi-period point clouds to recognizes the 3-D deformations. Results and discussion: The results show that the obtained results are very close to the GNSS data but with a much larger spatial monitoring range. The accuracy is higher than that of the SD method. Moreover, we analyze the statistical relationship between the point cloud block size and the deformation vector error and determine the optimal block size. The aim of this article is to optimize the deformation analysis method and improve its accuracy to provide techniques and ideas for the wider surface deformation monitoring research field. For instance, combining this method with data from contact methods constructs a 3D overall deformation model of the mountain, enabling real-time monitoring and early warning of debris flows. [ABSTRACT FROM AUTHOR]

In this paper, we have demonstrated a narrow linewidth high power fiber laser emitting at a short wavelength of ~1050 nm. The fiber laser is based on a structure of master oscillator power amplification (MOPA) with an optimized fiber Bragg-grating-based laser cavity as the seed. Both stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) effects have been effectively suppressed by using a long passive fiber between the seed and the amplifier. Based on the fiber amplifier, we have ultimately boosted the narrow linewidth laser from ~40 W to 3.2 kW with a slope efficiency of 85.1% and a 3-dB linewidth of ~0.1 nm. The SRS suppression ratio of the laser is ~29.7 dB at maximum power. Due to our fiber mode control strategies, the beam quality always stays near-diffraction-limited while amplifying, and the measured M2 factor is ~1.4 at the maximum power. Further increase in output power is limited by the SBS effect. [ABSTRACT FROM AUTHOR]

In this paper, an innovative approach is introduced to address the noise issues associated with micro–cantilever array deflection measurement systems employing multiple lasers. Conventional systems are affected by laser mode hopping during switching, resulting in wavelength instability and beam spot fluctuations that take several hundred milliseconds to stabilize. To mitigate these limitations, a high–speed laser modulation technique is utilized, leveraging the averaging effect over multiple modulation cycles within the sampling window. By driving the lasers with a high–frequency carrier signal, a low–noise and stable output suitable for micro–cantilever beam deflection measurement is achieved. The effectiveness of this approach is demonstrated by simultaneously modulating the lasers and rapidly observing the spectral and centroid variations during high–speed switching using a custom–built high–speed spectrometer. The centroid fluctuations are also analyzed under different modulation frequencies. The experimental results confirm that the high–speed modulation method can reduce the standard deviation of beam spot fluctuations by more than 90%, leading to significant improvements in noise reduction compared to traditional laser switching methods. The proposed high–speed laser modulation approach offers a promising solution for enhancing the precision and stability of multi–laser micro–cantilever array deflection measurement systems. [ABSTRACT FROM AUTHOR]

Although the field of geomatics has seen multiple technological advances in recent years which enabled new applications and simplified the consolidated ones, some tasks remain challenging, inefficient, and time- and cost-consuming. This is the case of accurate tridimensional surveys of narrow spaces. Static laser scanning is an accurate and reliable approach but impractical for extensive tunnel environments; on the other hand, portable laser scanning is time-effective and efficient but not very reliable without ground control constraints. This paper describes the development process of a novel image-based multi-camera system meant to solve this specific problem: delivering accurate, reliable, and efficient results. The development is illustrated from the system conceptualization and initial investigations to the design choices and requirements for accuracy. The resulting working prototype has been put to the test to verify the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

In this work, we focus on the prediction of the influence of CO2 laser parameters on the kerf properties of cut spruce wood. Laser kerf cutting is mainly characterized by the width of kerf and the width of the heat-affected zone, which depend on the laser power, cutting speed, and structure of the cut wood, represented by the number of cut annual rings. According to the measurement results and ANN prediction results, for lower values of the laser power (P) and cutting speed (v), the effect of annual rings (ARs) is non-negligible. The results of the sensitivity analysis show that the effect of v increases at higher energy density (E) values. With P in the range between 100 and 500 W, v values between 3 and 50 mm·s−1, and AR numbers between 3 and 11, the combination of P = 200 W and v = 50 mm·s−1, regardless of the AR value, leads to the best cut quality for spruce wood. In this paper, the main goal is to show how changes in the input parameters affect the characteristics of the cutting kerf and heat-affected zones for all possible input parameter values. [ABSTRACT FROM AUTHOR]

Existing galvanometer-based laser-scanning systems are challenging to apply in multi-scale 3D reconstruction because of the difficulty in achieving a balance between a high reconstruction accuracy and a wide reconstruction range. This paper presents a novel method that synchronizes laser scanning by switching the field-of-view (FOV) of a camera using multi-galvanometers. Beyond the advanced hardware setup, we establish a comprehensive geometric model of the system by modeling dynamic camera, dynamic laser, and their combined interaction. Furthermore, since existing calibration methods mainly focus on either dynamic lasers or dynamic cameras and have certain limitations, we propose a novel high-precision and flexible calibration method by constructing an error model and minimizing the objective function. The performance of the proposed method was evaluated by scanning standard components. The results show that the proposed 3D reconstruction system achieves an accuracy of 0.3 mm when the measurement range is extended to 1100 mm × 1300 mm × 650 mm. This demonstrates that for meter-scale reconstruction ranges, a sub-millimeter measurement accuracy is achieved, indicating that the proposed method realizes multi-scale 3D reconstruction and simultaneously allows for high-precision and wide-range 3D reconstruction in industrial applications. [ABSTRACT FROM AUTHOR]