Beam Attenuation Research Articles

Physical drivers of bio-optical properties in the Guangdong-Hong Kong-Macao Greater Bay Area during the winter dry season

Understanding the variability of bio-optical properties in coastal seas is essential to assessing the impact of natural and anthropogenic activities on the quality of the coastal environments and their resources. This study investigated the vertical distribution of bio-optical properties and their potential driving forces in the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) using a bio-optical dataset collected during the winter dry season. The hydrographic and biogeochemical properties observed across the GBA exhibited significant spatial variability, allowing the classification of the waters into three distinct regions: estuarine diluted water (EDW), Guangdong coastal current water (GCCW), and dense shelf water (DSW). Our findings show that EDW exhibited beam attenuation and optical backscatter coefficients an order of magnitude greater compared to the other two regions, which was attributed to factors such as higher concentrations of suspended particulate matter and organic material from estuarine sources. In contrast, the GCCW was characterized by lower salinity, temperature, and suspended particulate matter and displayed reduced turbidity near the coast, whereas nutrient-rich GCCW waters transported to the mid-shelf region supported increased phytoplankton biomass and a greater abundance of micro-phytoplankton. By exploring the bio-optical characteristics and their underlying processes in the GBA, this study enhances our understanding of the complex dynamics shaping the optical properties of coastal waters in this heavily urbanized region.

Assessment of tissue-air ratios in epoxy resin and PMMA phantoms for radiation dosimetry: findings from experimental measurements and Monte Carlo simulations.

This study assesses radiation doses in multi-slice computed tomography (CT) using epoxy resin and PMMA phantoms, focusing on the relationship between TAR (tissue air ratio) and kilovoltage peak (kVp). The research was conducted using a Hitachi Supria 16-slice CT scanner. An epoxy resin phantom was fabricated from commercially available materials, to simulate human tissue. The phantom contained four peripheral inserts and one central insert for dose measurement, with optically stimulated luminescent dosimeters positioned at various depths (2 to 10cm). Monte Carlo simulations were executed using the Geant4 Application for Tomographic Emission toolkit (GATE) to model photon transport, with the x-ray spectrum generated using SpekPy software. A non-linear fitting model was developed to describe the TAR-kVp relationship across different depths for epoxy resin and PMMA. Results indicated that TAR values were higher at low depths (2cm) and decreased with increasing depth, reflecting the x-ray beam's attenuation. For instance, at 80 kVp and 2cm depth, the experimental TAR for PMMA was 1.102 ± 0.011, closely matching the MC simulation value of 1.110 ± 0.036, resulting in a small difference of 0.7%. At a depth of 10cm, the experimental TAR for PMMA decreased to 0.245 ± 0.006, while the MC TAR was 0.248 ± 0.016, with a relative difference of 1.2%. Similar trends were observed for epoxy resin, where the experimental TAR ranged from 1.070 ± 0.014 at 2cm to 0.235 ± 0.009 at 10cm, while MC simulation values ranged from 1.080 ± 0.038 to 0.238 ± 0.017. Bland-Altman analysis confirmed these results, with mean differences of 0.008 for PMMA and 0.006 for epoxy resin, indicating high agreement between the experimental and simulated TAR values. This study highlights the importance of phantom material selection in dose assessment and the implications of TAR in dose correction within the context of diagnostic radiology.

Measurement of inherent optical properties of water based on multiple scattering profiles using underwater off-axis single-photon lidar.

Accurately measuring inherent optical properties (IOPs) in water is fundamental for characterizing light transmission in aquatic environments and advancing our understanding of biogeochemical processes. Lidar, with its capability for continuous day-and-night observations and strong water penetration, holds great potential for detecting optical parameters in water. However, ocean lidar faces challenges in addressing ill-posed equations and mitigating the effects of multiple scattering when detecting IOPs. In this study, a method for IOP detection based on multiple scattering profiles is proposed and demonstrated. First, a semi-analytic Monte Carlo approach was applied to analyze the relationship between multiple scattering profiles measured by off-axis lidar and IOPs. Next, a tank experiment was conducted to establish an analytical expression for this relationship. Subsequently, field experiments were carried out in the South China Sea using underwater single-photon lidar. Compared to in-situ measurements, the statistical root mean square error values were 0.007 m-1 for the scattering coefficient, 0.012 m-1 for the beam attenuation coefficient, and 0.014 m-1 for the absorption coefficient, validating the feasibility of the proposed method. Overall, this new IOP measurement approach is expected to contribute to advances in ocean biogeochemical cycle research.

Material imaging study of 3D printing materials for diagnostic radiology phantom development

The 3D printing techniques have found applications across diverse fields, significantly enhancing design and manufacturing processes. The impact of this growth is particularly notable in radiology, where 3D printing has been applied to developing quality control tools and advancing dosimetry techniques. 3D printing has the advantage of having a wide variety of plastic materials which can be used in the manufacturing process; there is a scarcity of work developed to evaluate the attenuation of the x-ray beam of the materials used in printing 3D models for phantom development. This paper aims to show our results on the imaging characteristics investigation of 15 3D printable materials. 3D objects were printed as cubes of 20 x 20 x 20 mm3 with a 100% infill and 45°/45° rectilinear structural pattern, and images acquired in a DR X-ray unit were analyzed with ImageJ software. Imaging pixel values, Signal-to-Noise Ratio – SNR and Contrast-to-Noise Ratio – CNR were evaluated and compared between the 3D-printed cubes and a standard chest phantom. When comparing the SNR for plastic materials and chest structures, significant differences were found. Similar results were found for the CNR. The differences were noted for both plastic materials, Tungsten and Bismuth, that demonstrated statistically significant values of SNR compared to the lung (p < 0.0001) and right rib (p < 0.0001). Tungsten and Bismuth filaments were found to have the potential to represent the SNR for intermediary and high-density structures. Scapula was the only anatomical structure with no statistically significant difference of the CNR for SILK (p ≥ 0.074), ABS (p ≥ 0.086), PVA (p ≥ 0.917) and ABSpremium (p ≥ 0.955). The study of potential radiological 3D printing materials for diagnostic radiology phantom development revealed important imaging characteristics for the plastic materials using the Fused Filament Fabrication technique.

Method for Estimating the Diffuse Attenuation Coefficient from the Beam Attenuation Coefficient in the Waters of the Black Sea

The vertical attenuation coefficient of downward irradiance is one of the hydro-optical characteristics that determine the parameters of the light field in the sea. Information from the vertical attenuation coefficient of downward irradiance (or the diffuse attenuation coefficient) is necessary when determining an important biological and ecological parameter of water basin — the thickness of the euphotic layer. A possible method for estimating the vertical attenuation coefficient of downward irradiance (or the diffuse attenuation coefficient) from measurements of the beam attenuation coefficient at a wavelength of 525 nm for the Black Sea waters is described. The Black Sea waters are characterized by an increased content of dissolved organic matter and belong to type II waters (according to the Morel classification). Examples of the application of the method are given, which showed a quite high correlation (R = 0.85) between the values of the vertical attenuation coefficient of downward irradiance determined from in situ measurements of underwater irradiance with a photometer and calculated from in situ measurements of the beam attenuation coefficient with a transparency meter. The standard deviation of the calculated values from the measured ones is 0.008 m–1, the maximum deviation is 0.023 m–1.

A comparison of the Information Content of Orthogonally Polarized Components of Lidar Echo Signal for Evaluating Hydrooptical Characteristics of the Near-Surface Layer

A series of lidar measurements were conducted at stations with a homogeneous vertical distribution of hydrooptical char acteristics in the near-surface layer using a two-channel shipborne polarization lidar PLD-1. Lidar sounding was accompanied by synchronous contact measurements of a number of hydrooptical characteristics. A large dataset of measurement data was obtained in waters where hydrooptical characteristics varied widely. As a result of the statistical processing of these data, regression relationships were obtained linking the seawater beam attenuation coefficient c, absorption coefficient a, and diffuse attenuation coefficient Kd to the lidar attenuation coefficients of the co- and cross-polarized components. In most cases, a linear relationship between hydrooptical characteristics and the lidar attenuation coefficients of the polarized components is observed. These rela tionships are characterized by high values of the coefficient of determination — from 0.8 to 0.95. An exception is the relationship between the seawater beam attenuation coefficient c and the lidar attenuation coefficient of the cross-polarized component, where a second-degree polynomial is used to describe this relationship (coefficient of determination is 0.88). Data on the hydrooptical characteristics obtained using the cross-polarized component of the lidar echo signal mostly duplicate the data of the co-polarized component. However, the use of a two-channel optical receiving system increases the reliability and accuracy of the obtained data and provides the possibility of controlling the homogeneity of the underwater section of the sounding path.

Mechanical performance of laser powder bed fused Ti-6Al-4V: The influence of filter condition and part location

Deteriorated filter condition in laser powder bed fusion (L-PBF) systems may negatively impact shield gas flow, causing inadequate spatter particle/plume removal, leading to laser beam attenuation and reduction in melt pool depth, and potentially causing more frequent formation of volumetric defects. This work investigated the effects of filter condition and part location on the micro-/defect-structure and mechanical behavior, including tensile and fatigue, of Ti-6Al-4V parts fabricated by L-PBF. Interestingly, within the manufacturer recommended service intervals, no specific effect of filter condition could be observed on the micro-/defect-structure or the mechanical behavior of the fabricated parts. However, the parts’ defect-structures were affected by their location, with ones located near the center of the build plate having less porosity than the ones located away. Although these defects did not affect the tensile properties, they frequently observed to initiate fatigue cracks (the critical defects sizes were often in the range of a few tens of micrometers). Therefore, their sensitivity to location resulted in the location dependence of the fatigue behavior.

Clinical Characteristics, Risk Factors, and Predictors of Nonobese Fatty Liver Disease: A Cross-Sectional Study.

This study aimed to investigate the risk factors and predictors of non-obese fatty liver disease in the Chinese population. A total of 6,014 adults who underwent physical examinations at Union Hospital of Huazhong University of Science and Technology from March 2019 to March 2023 were included in this study. Fatty liver disease was diagnosed based on at least two of the following criteria: diffuse echo patterns relative to the liver, spleen, and kidney; ultrasonic beam attenuation; and poor intrahepatic visual details. The associations between non-obese fatty liver and gender, age, total bilirubin(TBIL), direct bilirubin(DBIL), alanine aminotransferase(ALT), aspartate aminotransferase(AST), glutamine transferase(GGT), alkaline phosphatase(ALP), triglycerides(TG), total cholesterol(TC), high-density lipoprotein cholesterol(HDLC), low-density lipoprotein cholesterol(LDLC), urea nitrogen(BUN), creatinine(Cr), uric acid(UA), Central nervous system sensitivity PTFQI, TSHI, TT4RI, TFQI, Peripheral sensitivity, free thyroxine(FT4), thyroid-stimulating hormone(TSH), triiodothyronine(FT3), fasting blood glucose(FBG), systolic blood pressure(SBP), diastolic blood pressure(DBP), body mass index(BMI) were analyzed via binary logistic regression. Correlation between non-obese fatty liver and high blood lipids, hypertension, hyperuricemia, diabetes, thyroid dysfunction were analyzed using the Pearson and Spearman methods. ROC curve was used to evaluate the diagnostic effect of the indicator. Compared with the normal group, age, proportion of males, ALT, AST, GGT, ALP, TG, TC, BUN, Cr, UA, TSHI, TT4RI, FT3/FT4, TSH, FT3, FBG, SBP, DBP and BMI in the disease group were significantly higher. The prevalence of non-obese fatty liver was associated with hyperlipidemia, hypertension, hyperuricemia and diabetes. Gender, age, DBIL, ALT, ALP, TG, HDL-C, LDL-C, BUN, UA, FBG, DBP, BMI were independent risk factors for non-obese fatty liver.FT3/FT4 may be considered as a predictor of nonobese fatty liver. Risk factors for non-obese fatty liver may include sex, age, TG, TC, BMI, etc. Hyperlipidemia, hypertension, hyperuricemia and diabetes mellitus are related to non-obese fatty liver. FT3/FT4 may be a predictor of non-obese fatty liver disease.

Femtotesla atomic magnetometer with counter-propagating optical sideband pumping.

The ultrasensitive magnetometer has a vital importance in fundamental research and applications. Currently, the spin-exchange relaxation-free (SERF) atomic magnetometer has been reported with a sensitivity around the level of fT/Hz1/2. To enhance the sensitivity, a gradiometer configuration has usually been introduced to cancel the common-mode noise between two separate channels. However, the signal and response from different channels are not the same due to the attenuation of the pump beam. Here, we proposed a counter-propagating optical sideband pumping method to polarize the atoms, using the electro-optic modulator to modulate the single-pump beam, generating two symmetrically red- and blue-detuned sidebands of frequency. This scheme leads to a significant reduction of undesirable effects coming along with the optical pumping, such as light shifts and spatial inhomogeneity in atomic spin polarization. With the help of this pumping scheme, the two channels have the same magnetic response, and we have built a gradiometer atomic magnetometer with a sensitivity of 0.5 fT/Hz1/2 ranging from 5 to 40 Hz. Our results propose the possibility of creating larger arrays of atomic magnetometers (AMs) with high sensitivity and spatial resolution based on single-vapor cells for magnetocardiography and magnetoencephalography imaging or searching for exotic spin-dependent interactions.

Wideband vibration attenuation of a metamaterial beam via integrated hardening and softening nonlinear resonators

Wideband vibration attenuation of a metamaterial beam via integrated hardening and softening nonlinear resonators

Monitoring evolutionary damage of bended concrete beams subjected to freeze-thaw cycling through piezoelectric-enabled wave propagation method

Tunnels in cold regions are often subjected to freeze-thaw cycling, which poses a great challenge to a large number of tunnels in operation or to be built in these regions. Therefore, structural health monitoring (SHM) for lining concrete in cold regions is essential to ensure the safety and long-term operation of tunnels. In this study, the wave propagation method (WPM) is applied for the first time to monitor the cyclic freeze-thaw damage of lining concrete. First of all, the failure behaviors of concrete beams subjected to the coupling effect of flexural loading and freeze-thaw cycling are investigated. Particularly, the authors propose a refined numerical model to simulate the freeze-thaw cycling damage process of concrete beams considering the ice-water phase transition and concrete elastoplastic damage. Based on the numerical results, the internal damage expansion and flexural strength attenuation of concrete beams are revealed. Furthermore, the dynamic attenuation characteristics of stress waves are analyzed by using the wavelet packet decomposition and continuous wavelet transform to reveal. In addition, the WPM-based energy index is proposed to characterize the freeze-thaw damage degree of the lining concrete. A strong correlation is found between the stress wave signal and freeze-thaw damage, with a favorable correlation coefficient of 0.932, suggesting the excellent performance of the WPM in assessing the freeze-thaw damage of lining concrete. This research sufficiently manifests the applicability of the WPM method to monitoring the freeze-thaw damage within cold regional tunnel linings.

Investigation on the transmission attenuation of Bessel-Gaussian beams in a dusty environment

This paper delves into the transmission dynamics of Bessel-Gaussian (BG) beams in three distinct dusty environments, leveraging the Generalized Lorenz-Mie Theory (GLMT) alongside a single scattering model for a comprehensive analysis. Through numerical simulations, the study explores the interaction between dust particle scattering and the attenuation and transmittance behaviors of BG beams, elucidating the influences of varying particle concentrations and visibility conditions typical of floating dust, blowing sand, and sandstorms. The findings reveal numerous determinants, including particle number concentration, optical visibility, wavelength, orbital angular momentum (OAM) modes, waist radius, cone angle, and polarization states, which significantly affect the transmission performance of BG beams in dusty conditions. Notably, the attenuation rate decreases with increasing wavelengths and higher OAM modes, thereby extending effective transmission distances. Furthermore, the strategic use of linear polarization emerges as an optimal approach for enhancing BG beam transmission efficiency in dust-rich environments. These insights are crucial for optimizing BG beam transmission in real-world applications, marking a significant advancement in the field.

Advances of the Holographic Technique to Test the Basic Properties of the Thin-Film Organics: Refractivity Change and Novel Mechanism of the Nonlinear Attenuation Prediction.

A large number of the thin-film organic structures (polyimides, 2-cyclooctylarnino-5-nitropyridine, N-(4-nitrophenyl)-(L)-prolinol, 2-(n-Prolinol)-5-nitropyridine) sensitized with the different types of the nano-objects (fullerenes, carbon nanotubes, quantum dots, shungites, reduced graphene oxides) are presented, which are studied using the holographic technique under the Raman-Nath diffraction conditions. Pulsed laser irradiation testing of these materials predicts a dramatic increase of the laser-induced refractive index, which is in several orders of the magnitude greater compared to pure materials. The estimated nonlinear refraction coefficients and the cubic nonlinearities for the materials studied are close to or larger than those known for volumetric inorganic crystals. The role of the intermolecular charge transfer complex formation is considered as the essential in the refractivity increase in nano-objects-doped organics. As a new idea, the shift of charge from the intramolecular donor fragment to the intermolecular acceptors can be proposed as the development of Janus particles. The energy losses via diffraction are considered as an additional mechanism to explain the nonlinear attenuation of the laser beam.

Monte Carlo calculated absorbed-dose energy dependence of EBT3 and EBT4 films for 5-200 MeV electrons and 100 keV-15 MeV photons.

To use Monte Carlo simulations to study the absorbed-dose energy dependence of GAFChromic EBT3 and EBT4 films for 5-200MeV electron beams and 100keV-15MeV photon beams considering two film compositions: a previous EBT3 composition (Bekerat etal.) and the final composition of EBT3/current composition of EBT4 (Palmer etal.). A water phantom was simulated with films at 5-50mm depth in 5mm intervals. The water phantom was irradiated with flat, monoenergetic 5-200MeV electron beams and 100 and 150keV kilovoltage and 1-15MeV megavoltage photon beams and the dose to the active layer of the films was scored. Simulations were rerun with the films defined as water to compare the absorbed-dose response of film to water, . For electrons, the Bekerat etal. composition had variations in of up to from 5to200MeV. Similarly, the Palmer etal. composition had differences in up to from 5to200MeV. For photons, varied up to and from 100keV to 15MeV for the Bekerat etal. and Palmer etal. compositions, respectively. The depth of films did not appear to significantly affect for photons at any energy and for electrons at energies 50MeV. However, for 5 and 10MeV electrons, decreases of up to in were seen due to stacked films and increased beam attenuation in films compared to water. The up to and variations in for electrons and photons, respectively, across the energies considered in this study indicate the importance of calibrating films with the energy intended for measurement. Additionally, this work emphasizes potential issues with stacking films to measure depth dose curves, particularly for electron beams with energies 10MeV.

Selection of X-ray Tube Settings for Relative Bone Density Quantification in the Knee Joint of Cats Using Computed Digital Absorptiometry.

Bone mineral density (BMD) varies with aging and both systemic and local diseases; however, such evidence is lacking in feline medicine. This may be due to the need for general anesthesia in cats for direct BMD measurements using dual-energy X-ray absorptiometry (DXA) or quantitative computed tomography (QCT). In this study, computed digital absorptiometry (CDA), an indirect relative BMD-measuring method, was optimized to select an X-ray tube setting for the quantitative assessment of the feline knee joint. The knee joints of nine cats were radiographically imaged and processed using the CDA method with an aluminum density standard and five X-ray tube settings (from 50 to 80 kV; between 1.2 and 12 mAs). The reference attenuation of the X-ray beam for ten steps (S1-S10) of the density standard was recorded in Hounsfield units (HU), compared between X-ray tube settings, and used to determine the ranges of relative density applied for radiograph decomposition. The relative density decreased (p < 0.0001) with an increase in kV and dispersed with an increase in mAs. Then, the percentage of color pixels (%color pixels), representing ranges of relative density, was compared among S1-S10 and used for the recognition of background artifacts. The %color pixels was the highest for low steps and the lowest for high steps (p < 0.0001), regardless of X-ray tube settings. The X-ray tube setting was considered the most beneficial when it effectively covered the lowest possible HU ranges without inducing background artifacts. In conclusion, for further clinical application of the CDA method for quantitative research on knee joint OA in cats, 60 kV and 1.2 mAs settings are recommended.

Quantitative and qualitative performance evaluation of commercial metal artifact reduction methods: Dosimetric effects on the treatment planning

The presence of metal implants within CT imaging causes severe attenuation of the X-ray beam. Due to the incomplete information recorded by CT detectors, artifacts in the form of streaks and dark bands would appear in the resulting CT images. The metal-induced artifacts would firstly affect the quantitative accuracy of CT imaging, and consequently, the radiation treatment planning and dose estimation in radiation therapy. To address this issue, CT scanner vendors have implemented metal artifact reduction (MAR) algorithms to avoid such artifacts and enhance the overall quality of CT images. The orthopedic-MAR (OMAR) and normalized MAR (NMAR) algorithms are the most well-known metal artifact reduction (MAR) algorithms, used worldwide. These algorithms have been implemented on Philips and Siemens scanners, respectively. In this study, we set out to quantitatively and qualitatively evaluate the effectiveness of these two MAR algorithms and their impact on accurate radiation treatment planning and CT-based dosimetry. The quantitative metrics measured on the simulated metal artifact dataset demonstrated superior performance of the OMAR technique over the NMAR one in metal artifact reduction. The analysis of radiation treatment planning using the OMAR and NMAR techniques in the corrected CT images showed that the OMAR technique reduced the toxicity of healthy tissues by 10% compared to the uncorrected CT images.

A versatile electrochemical cell for in-situ GI-XRD measurements on lab-scale XRD devices

In-situ X-ray diffraction (XRD) cells for electrochemical experiments suffer from strong attenuation of primary and diffracted beams within the electrolyte solution. To reduce the intensity loss of the X-rays, the use of a thin layer of electrolyte solution is an essential element of the conventional cell design. On the other hand, the thin layer electrolyte geometry is a considerable limitation for electrochemical measurements. To overcome these drawbacks a versatile electrochemical cell for in-situ GI-XRD measurements was constructed and used for the electrodeposition of Cu2O thin films on a copper substrate.In this design, a thin copper metal film working electrode is applied on a polyimide foil and then backside-illuminated in GI-XRD geometry. In this way, the XRD pattern is measured from the electrolyte/electrode interface of the working electrode. The X-rays only have to penetrate the polymer foil and the sputtered metal layer, resulting in high-intensity signals.In this work, we demonstrate the abilities of the in-situ cell with quantitative measurements of cathodic deposition of Cu2O thin layers. The results show a good agreement between the diffracted X-ray peak intensities and the calculated and measured thicknesses of the oxide layers. The cell design allows the structural characterization of electrode surfaces during electrochemical measurements without the disadvantages of thin layer cells and therefore does not require high intensity synchrotron radiation to perform X-ray diffraction during electrochemical investigations.

Beam attenuation coefficient for different water turbidities

Interest in underwater optical communications has grown in recent years. A key aspect for the development of such systems is the modeling of light signal propagation in turbid water. In this paper, we present an experimental estimation of the light beam attenuation coefficient by varying the turbid water conditions with pollutants and also considering sea and lake water. The estimation of the beam attenuation coefficient c is based on laboratory measurements of the optical signal-to-noise ratio (SNR) for underwater transmissions and an analytical model of c as a function of SNR. To assess the reliability of the estimation procedure, c has been estimated in the case of clear water and the value obtained is very close to that reported in many studies. Next, c has been estimated for different water conditions. In particular, the results show that the value of c for polluted waters varies between 2.875m−1 and 15.675m−1. In addition, the values of c for lake and clear sea water are 0.6m−1 and 0.9m−1, respectively.

Investigating laser beam shadowing and powder particle dynamics in directed energy deposition through high-fidelity modelling and high-speed imaging

Laser beam shadowing in directed energy deposition process occurs when in-flight powder particles partially block the laser beam, preventing it from fully reaching the melt pool. This blockage alters the beam's profile, introducing spatio-temporal randomness in heat transfer to the melt pool and affecting its stability. This study utilizes a novel high-fidelity multiphysics model to quantitatively analyze gas-powder stream dynamics and laser-particle interactions. It specifically focuses on dynamic variations in laser beam shadowing, attenuation, and reflection of the laser beam radiant energy, along with powder particles temperature prediction from in-flight heating, accounting for multiple reflection phenomena. Gas-particle dynamics is modeled using a fully coupled CFD-DEM approach, while laser-particle in-flight interactions are predicted using a ray-tracing-based photon discretization method. Modeling predicted that interactions between the laser beam and the in-flight powder stream could result in energy losses up to approximately 70 % due to shadowing and attenuation. The study comprehensively explored the spatio-temporal variations in the attenuated laser beam profile, revealing significant deviations from its initial Gaussian profile and substantial stochasticity and randomness over time. To confirm the modeling results and correlate computational predictions with experimental data, high-speed visible imaging of the powder stream, both with and without the melt pool, along with laser beam attenuation measurements using a photodiode system, were conducted. The model's predictions of particle velocity and laser beam attenuation characteristics aligned with the results from these experiments. Modeling and high-speed imaging demonstrated that in-flight heating caused some particles to melt and few others to reach the vaporization threshold. High-speed imaging further validated these numerical findings by examining the interaction of heated particles with the melt pool across different phases (solid, liquid, and partially vaporized). A significant observation was the increased velocities of partially vaporized particles due to recoil pressure from selective vaporization, which led to the formation of deep craters in the melt pool resulting from high-speed impact.

X-Ray Multibeam Ptychography at up to 20 keV: Nano-Lithography Enhances X-Ray Nano-Imaging.

Hard X-rays are needed for non-destructive nano-imaging of solid matter. Synchrotron radiation facilities (SRF) provide the highest-quality images with single-digit nm resolution using advanced techniques such as X-ray ptychography. However, the resolution or field of view is ultimately constrained by the available coherent flux. To address this, the beam's incoherent fraction can be exploited using multiple parallel beams in an X-ray multibeam ptychography (MBP) approach. This expands the domain of X-ray ptychography to larger samples or more rapid measurements. Both qualities favor the study of complex composite or functional samples, such as catalysts, energy materials, or electronic devices. The challenge of performing ptychography at high energy and with many parallel beams must be overcome to extract the full advantages for extended samples while minimizing beam attenuation. Here, that challenge is overcome by creating a lens array using cutting-edge laser printing technology and applying it to perform scanning with MBP with up to 12 beams and at photon energies of 13 and 20 keV. This exceeds the measurement limits of conventional hard X-ray ptychography without compromising image quality for various samples: Siemens star test pattern, Ni/Al2O3 catalyst, microchip, and gold nano-crystalclusters.