Intensity Pattern Research Articles

Acoustic spin-controlled orbital rotations in double spiral acoustic beams

Similar to optical spin-orbit interactions (SOIs), acoustic SOIs are anticipated to offer fresh perspectives and capabilities for acoustic manipulation beyond conventional scalar degrees of freedom. However, the acoustic extrinsic SOIs caused by particular properties of the medium were seldom explored. Here, the acoustic extrinsic SOI is observed in a double spiral acoustic beam (DSAB), as evidenced by the rotation of the spatial intensity pattern along the propagation axis. The interaction of the acoustic plane wave with the well-designed artificial flat structure generates two non-paraxial focused acoustic vortices (NFAVs) with different spin angular momentums. The coaxial coupling between them leads to acoustic spin-controlled orbital rotation (SOR). Theoretical formulations, supported by numerical simulations and experimental results, are provided to demonstrate the validity of acoustic SOR. Our work provides new perspectives and capabilities for understanding sound processing, and may open an avenue for the development of spin-orbit acoustics.

Generation of dual bi-power-exponents helico-conical beams employing spin-isolated geometric metasurface

Unlike traditional optical vortex (OV), helico-conical optical beams (HCOBs) carry orbital angular momentum (OAM) related to the beam’s radius and exhibit a helical intensity pattern, drawing widespread attention in fields such as optical communication and optical tweezers. In this study, we introduce two independent power-exponents into the HCOB configuration and employ spin-isolated geometric phase metasurfaces to simultaneously generate dual bi-power-exponent helico-conical beams (BPE-HCBs). This innovative approach allows unprecedented control over the beams’ shape and intensity using only simple linearly polarized (LP) incident light, facilitating the transformation from dual helical structures to multi-ring hollow beams and vector vortex beams (VVBs) patterns. Our research not only simplifies the design process of metasurfaces but also demonstrates their significant capabilities in generating and manipulating complex OAM beam patterns, paving the way for innovative designs in integrated optical systems.

Designing Effective Low-Impact Developments for a Changing Climate: A HYDRUS-Based Vadose Zone Modeling Approach

Low-Impact Developments (LIDs), like green roofs and bioretention cells, are vital for managing stormwater and reducing pollution. Amidst climate change, assessing both current and future LID systems is crucial. This study utilizes variably saturated flow modeling with the HYDRUS software (version 4.17) to analyze ten locations in Ontario, Canada, focusing on Toronto. Historical and projected climate data are used in flow modeling to assess long-term impacts. Future predicted storms, representing extreme precipitation events, derived from a regional climate model, were also used in the flow modeling. This enabled a comprehensive evaluation of LID performance under an evolving climate. A robust methodology is developed to analyze LID designs, exploring parameters like water inflow volumes, peak intensity, time delays, runoff dynamics, and ponding patterns. The findings indicate potential declines in LID performance attributed to rising water volumes, resulting in notable changes in infiltration for green roofs (100%) and bioretention facilities (50%) compared to historical conditions. Future climate predicted storms indicate reduced peak reductions and shorter time delays for green roofs, posing risks of flooding and erosion. Anticipated extreme precipitation is projected to increase ponding depths in bioretention facilities, resulting in untreated stormwater overflow and prolonged ponding times exceeding baseline conditions by up to 13 h at numerous Ontario locations.

Arterial Spin-Labeling Perfusion Lightbulb Sign: An Imaging Biomarker of Pediatric Posterior Fossa Hemangioblastoma.

Hemangioblastoma is a rare vascular tumor that occurs within the central nervous system in children. Differentiating hemangioblastoma from other posterior fossa tumors can be challenging on imaging, and preoperative diagnosis can change the neurosurgical approach. We hypothesize that a "lightbulb sign" on the arterial spin-labeling (ASL) sequence (diffuse homogeneous intense hyperperfusion within the solid component of the tumor) will provide additional imaging finding to differentiate hemangioblastoma from other posterior fossa tumors. In this retrospective comparative observational study, we only included pathology-proved cases of hemangioblastoma, while the control group consisted of other randomly selected pathology-proved posterior fossa tumors from January 2022 to January 2024. Two blinded neuroradiologists analyzed all applicable MRI sequences, including ASL sequence if available. ASL was analyzed for the lightbulb sign. Disagreements between the radiologists were resolved by a third pediatric neuroradiologist. χ2 and Fisher exact test were used to analyze the data. Ninety-five patients were enrolled in the study; 57 (60%) were boys. The median age at diagnosis was 8 years old (interquartile range: 3-14). Of the enrolled patients, 8 had hemangioblastoma, and 87 had other posterior fossa tumors, including medulloblastoma (n = 31), pilocytic astrocytoma (n = 23), posterior fossa ependymoma type A (n = 16), and other tumors (n = 17). The comparison of hemangioblastoma versus nonhemangioblastoma showed that peripheral edema (P = .02) and T2-flow void (P = .02) favor hemangioblastoma, whereas reduced diffusion (low ADC) (P = .002) and ventricular system extension (P = .001) favor nonhemangioblastoma tumors. Forty-two cases also had ASL perfusion sequences. While high perfusion favors hemangioblastoma (P = .03), the lightbulb sign shows a complete distinction because all the ASL series of hemangioblastoma cases (n = 4) showed the lightbulb sign, whereas none of the nonhemangioblastoma cases (n = 38) showed the sign (P < .001). Lightbulb-like intense and homogeneous hyperperfusion patterns on ASL are helpful in diagnosing posterior fossa hemangioblastoma in children.

Factors behind the resilience of rural startups

Rural areas are characterized by sparse population, low population density, remoteness, and population aging, which can discourage startups and undermine their financial performance, as the theory of urban agglomeration economies suggests. However, many studies have shown that companies created in rural areas survive longer than those created in urban areas, which seems contradictory. This paper aims to identify the factors that explain this rural resilience. We analyzed all of the startups founded in Spain over 10 years. We used statistical matching methods to test for the effect of the location while controlling for founding conditions and environmental factors. Our study confirmed that few startups are created in rural areas and they grow less, but their survival rate is slightly higher than those established in urban areas. We found that high subsidies, low operating costs, high labor intensity, a slow but low-risk growth pattern, and other foundational conditions and external factors contribute to explaining rural resilience. Nonetheless, additional factors, including the traits of rural entrepreneurs and the lack of alternatives to bankruptcy, as proposed by the entrepreneurial opportunity theory, also matter.

Probabilistic fragility assessment of slopes considering uncertainty associated with temporal patterns of rainfall intensity

The temporal patterns of rainfall intensity, characterized by the variability of rainfall intensity over time during a single rainfall event, play a crucial role in landslide triggering and evolution. However, the influence of temporal patterns of rainfall intensity on the fragility and reliability assessment of slope instability has received limited attention. This study presents a novel methodology for probabilistic slope fragility assessment accounting for uncertainty associated with the temporal patterns of rainfall intensity. Hourly-scale random time series for the rainfall event are generated, considering uncertainties in temporal patterns of rainfall intensity, using the statistical concepts of skewness and kurtosis within the Pearson system of distributions. A time-dependent seepage-stability mechanical model coupling the finite element method and limit equilibrium method for the slope under hourly-scale rainfall time series is established. Slope fragility assessment under rainfall is conducted, accounting for uncertainties in temporal patterns of rainfall intensity based on Monte Carlo simulation. An illustrative example is provided, focusing on a hypothetical soil slope in the southeastern coastal area of China, susceptible to rainfall-induced landslides. The impact of skewness and kurtosis of rainfall time series on the slope failure probability and failure time are examined.

High prevalence and low intensity of Echinophthirius horridus infection in seals revealed by high effort sampling

Seal lice (Echinophthirius horridus) are bloodsucking ectoparasites of phocid seals and vectors of pathogens like the heartworm, Acanthocheilonema spirocauda. Grey and harbour seal populations are recovering in German waters and wildlife health surveillance is crucial for wildlife conservation. A new, high effort sampling protocol for seal lice was applied for grey and harbour seals along the German North- and Baltic Sea coast. Freshly dead seals were systematically sampled within a health monitoring of stranded seals over 12 months. Prevalence, intensity and distribution patterns of seal lice were analysed. 58% of harbour seals (n = 71) and 70% of grey seals (n = 10) were infected with seal lice. A majority of harbour seals displayed mild levels of infection, while three were moderately and two were severely infected. The head was the preferred predilection site, indicating that E. horridus prefers body areas with frequent access to atmospheric oxygen. Nits and different developmental stages were recorded in all age classes in grey and harbour seals in all seasons. For the first time, copulating specimens of E. horridus were recorded on a dead harbour seal, highlighting that E. horridus reproduces throughout the year on seals of all age classes in German waters.

High parasite prevalence in an ecosystem engineer correlated with both local- and landscape-level factors.

Spatial variation in parasitic infection may have many physical and biological drivers. Uncovering these drivers may be especially important for parasites of ecosystem engineers because the engineers are foundational to their communities. Oysters are an important coastal ecosystem engineer that have declined drastically worldwide, in part due to enhanced cases of lethal oyster diseases, such as Dermo and MSX, caused by the protozoan parasites Perkinsus marinus and Haplosporidium nelsoni, respectively. Besides water quality and hydrodynamics, there is little information on how other variables influence the prevalence and intensity of these pathogens in oysters across a regional scale. To examine drivers of spatial variation in these oyster parasites-including host size, local reef properties, and landscape properties-we sampled 24 reefs systematically spread along the coast of Georgia, USA. Across sites, we found universally high prevalence of oysters with at least one of these parasites (91.02% ± 8.89, mean ± SD). Not only are high levels of parasite prevalence potentially problematic for a pivotal ecosystem engineer, but also low spatial variability may limit the explanatory power of variables across a regional scale. Our statistical models explained between 18 and 42% of the variation in spatial patterns of prevalence and intensity of these microparasites. Interestingly, landscape context was a positive predictor of P. marinus, but a negative predictor of H. nelsoni. Overall, our findings suggest that factors driving parasite prevalence and intensity operate across multiple spatial scales, and the same factor can both facilitate and hinder different parasites within the same host species.

Hydrothermally deposited Sb2S3 absorber, and a Sb2S3/CdS solar cell with VOC approaching 800 mV

We report the hydrothermal deposition of Sb2S3 thin film on top of CdS buffer layer, and the fabrication of prototype photovoltaic devices utilizing spiro-OMeTAD as the hole transport layer. The as-deposited films were amorphous, which transformed to polycrystalline after thermal processing. The pristine films were annealed at different temperatures and showed effective recrystallization at 350 °C which resulted in larger grains, intense XRD patterns, and significantly improved device parameters. The obtained VOC of 795 mV is among the highest reported for a Sb2S3 based solar cell. Deep level transient spectroscopy studies detected an electron trap with activation energy 0.61 eV in the pristine annealed absorber, which became deeper (0.66 eV) upon Na incorporation. However, the capture cross-section decreased by an order of magnitude, and the trap density halved. The reduction in the capture cross-section and trap density for the Na-incorporated device coincides with the improved EQE response in the mid- and long-wavelength regions and a 9 % increase in device efficiency. The light intensity dependence of VOC clearly demonstrated that Na incorporation reduced the trap-assisted recombination and facilitated efficient charge transport in the device.

IMG-22. ASL PERFUSION LIGHTBULB SIGN: A POTENTIAL PATHOGNOMONIC FEATURE OF PEDIATRIC POSTERIOR FOSSA HEMANGIOBLASTOMA

Abstract INTRODUCTION Hemangioblastoma is a rare vascular tumor which occurs within the central nervous system in children. Differentiating hemangioblastoma from other posterior fossa tumors can be challenging on imaging and preoperative diagnosis can change neurosurgical approach. We hypothesize a ‘lightbulb sign’ (diffuse homogenous intense hyperperfusion within solid component of tumor) will help differentiate hemangioblastoma from other posterior fossa tumors. METHODS In this retrospective case-control study, we only included pathology-proven cases of hemangioblastoma, while the control group consisted of other randomly selected pathology-proven posterior fossa tumors from January 2022 to January 2024. Two blinded neuroradiologists analyzed all applicable MRI sequences. Their perfusion analysis also included the “lightbulb sign” as an extra criterion. Disagreements between the radiologists were confirmed by a third pediatric neuroradiologist. Chi-square and Fisher’s exact test were used to analyze the data. RESULTS 95 patients were enrolled in the study, 57(60%) were male. The median age at diagnosis was 8 (IQR: 3-14). Out of the enrolled patients, 8 had hemangioblastoma, and 87 had other posterior fossa tumors, including medulloblastoma (n=31), pilocytic astrocytoma (n=23), posterior fossa ependymoma type A (n=16), and other tumors (n=17). The comparison of hemangioblastoma vs non-hemangioblastoma showed that peripheral edema (p=0.020, OR=1.8) and T2 flow void (p=0.021, OR=1.7) favors hemangioblastoma, whereas reduced diffusion (low ADC) (p=0.002, OR=2.3) and ventricular system extension (p=0.001, OR=2.4) favors non-hemangioblastoma tumors. 42 cases also had perfusion studies. While high perfusion favors hemangioblastoma (p=0.021, OR=2.9), the lightbulb sign shows a complete distinction since all the ASL series of hemangioblastoma cases (n=4) showed the lightbulb sign, whereas none of the non-hemangioblastoma cases (n=38) showed the sign (p&amp;lt;0.001). CONCLUSION Lightbulb-like intense and homogenous hyperperfusion pattern on ASL allows differentiation of hemangioblastoma from other posterior fossa tumors in children.

Spatial N-glycomics of the normal breast microenvironment reveals fucosylated and high-mannose N-glycan signatures related to BI-RADS density and ancestry.

Higher breast cancer mortality rates continue to disproportionally affect black women (BW) compared to white women (WW). This disparity is largely due to differences in tumor aggressiveness that can be related to distinct ancestry-associated breast tumor microenvironments (TMEs). Yet, characterization of the normal microenvironment (NME) in breast tissue and how they associate with breast cancer risk factors remains unknown. N-glycans, a glucose metabolism-linked post-translational modification, has not been characterized in normal breast tissue. We hypothesized that normal female breast tissue with distinct Breast Imaging and Reporting Data Systems (BI-RADS) categories have unique microenvironments based on N-glycan signatures that varies with genetic ancestries. Profiles of N-glycans were characterized in normal breast tissue from BW (n=20) and WW (n=20) at risk for breast cancer using matrix assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI). A total of 176 N-glycans (32 core-fucosylated and 144 noncore-fucosylated) were identified in the NME. We found that certain core-fucosylated, outer-arm fucosylated and high-mannose N-glycan structures had specific intensity patterns and histological distributions in the breast NME dependent on BI-RADS densities and ancestry. Normal breast tissue from BW, and not WW, with heterogeneously dense breast densities followed high-mannose patterns as seen in invasive ductal and lobular carcinomas. Lastly, lifestyles factors (e.g. age, menopausal status, Gail score, BMI, BI-RADS) differentially associated with fucosylated and high-mannose N-glycans based on ancestry. This study aims to decipher the molecular signatures in the breast NME from distinct ancestries towards improving the overall disparities in breast cancer burden.

Time-Resolved Ion Mobility Spectrometry with a Stop Flow Confined Volume Reaction Region.

An ion source concept is described where the sample flow is stopped in a confined volume of an ion mobility spectrometer creating time-dependent patterns of ion patterns of signal intensities for ions from mixtures of volatile organic compounds and improved signal-to-noise rate compared to conventional unidirectional drift gas flow. Hydrated protons from a corona discharge were introduced continuously into the confined volume with the sample in air at ambient pressure, and product ions were extracted continuously using an electric field for subsequent mobility analysis. Ion signal intensities for protonated monomers and proton bound dimers were measured and computationally extracted using mobilities from mobility spectra and exhibited distinct times of appearance over 30 s or more after sample injection. Models, and experimental findings with a ternary mixture, suggest that the separation of vapors as ions over time was consistent with differences in the reaction rate for reactions between primary ions from hydrated protons and constituents and from cross-reactions that follow the initial step of ionization. The findings suggest that the concept of stopped flow, introduced here for the first time, may provide a method for the temporal separation of atmospheric pressure ions. This separation relies on ion kinetics and does not require chromatographic technology.

Extraction of K2CO3 from empty palm fruit bunch ash and properties analysis

Empty oil palm fruit bunches (EPFB) are the largest solid waste generated from palm oil mills. Accounting for 21-23 % of the total fresh fruit bunches. EFB ash contains K (Potassium) which can be recovered as K2CO3 through extraction. This research aims to recover K2CO3 from empty oil palm fruit bunches (EPFB) as a catalyst raw material because it is alkaline using the K2CO3 extraction method from the ash of empty oil palm fruit bunches (EPFB), which begins with a combustion process at a temperature of 700 oC to obtain ash. Ash extraction was carried out in 2 stages using water as a solvent. The K2CO3 yield from empty palm fruit bunch ash reached 57.28 %. The alkalinity test showed that the K2CO3 content in the solid extract reached 85.91 %. The properties of the ash and K2CO3 produced were analyzed using XRF, XRD and FTIR. The results of XRF analysis show that the potassium content in the ash contains the element K (potassium) which is quite large, namely 71.24 % and after extraction the purity of potassium oxide reaches 97.08 %. XRD analysis of the results of the synthesis of potassium carbonate from empty oil palm fruit bunches showed that the intensity of the material beam was obtained in a 2ϴ pattern which was lower than the intensity pattern of pure potassium carbonate. The results of FTIR analysis show that the spectrum of carbonate ions from the EPFB C-O bend is visible at 1359,879 and 700.75 cm-1 and these results are similaire to the pure carbonate ion vibration mode.

Ohio River basin snow ablation and the role of rain‐on‐snow

AbstractSnow cover ablation within the Ohio River Basin (ORB) plays an important role in regional hydroclimatology, while also representing a potential hazard during large and rapid events. Rain‐on‐snow ablation is a particular challenge, where runoff rates are typically enhanced due to the dual inputs of snowmelt and liquid precipitation. Here, we present a 40‐year climatology of snow ablation events frequency, intensity, and timing for the ORB using a 4‐km gridded snow‐water‐equivalent dataset, focusing on the relative proportion of events caused by rain‐on‐snow and changes over time. Spatial patterns of snow ablation frequency and intensity mirror that of seasonal snowfall totals, with higher (lower) values in the northern and eastern (southern) portions of the basin. Rain‐on‐snow events represent approximately 40% of all ablation events within the basin and result in approximately 24%–25% more snow‐water‐equivalent loss than non‐rain‐on‐snow events, plus an additional 3–12 mm of liquid precipitation per event on average. Peak frequency of ablation and rain‐on‐snow events occurs in late winter and early spring, similar to that of the surrounding region. Over time, the frequency of ablation and rain‐on‐snow events has decreased in the northern and eastern portions of the basin, in some cases by as much as 30%. Trends in event magnitudes were more isolated but decreased across portions of central IN, northern KY, eastern OH and northern WV. Additionally, the magnitude of precipitation during rain‐on‐snow events has increased across the region, extending from northern KY into western PA by over 100% in many cases. Broadly, we find tendencies towards fewer events with less snow loss but more liquid precipitation that suggest complicated impacts to the hydroclimatology warranting further investigation.

Fostering Resilient Communities and Sustainable Tourism against Climate-Driven Disaster Risk in Gili Islands

Abstract Climate change exacerbates natural conditions and disasters. It increased the frequency and severity of droughts, rising sea levels leading to coastal erosion and flooding, more intense and unpredictable weather patterns, and the potential for stronger storm surges and tropical cyclones. These changes have significant impacts on the local ecosystems, water resources, and agriculture and ultimately affect the lives and livelihoods of the island’s residents. Additionally, the changes in ocean temperature and acidity due to climate change can disrupt marine ecosystems, affecting fisheries and coral reefs, which are vital for the island’s tourism industry. This research investigates the consequences of climate change-induced disaster risks on the Gili Islands, particularly drought and their implications for local tourism. Utilizing qualitative methods, the study focuses on developing strategies for sustainable tourism and bolstering community capacity across the islands. Prioritizing the establishment of a strong nexus and resilient community, the research underscores the essential role of collaboration and education. It highlights the importance of active engagement from well-resourced hotels and resorts in addressing these challenges. The study also proposes innovative business processes to enhance connections between hotels, resorts, the government, and the local community. Ultimately, the research aims to provide a roadmap for sustainable tourism practices, fostering a resilient community and facilitating effective cooperation among stakeholders to mitigate the impacts of climate change in the Gili Islands.

Nature-based solution using a bioengineering strategy for soil erosion control in tropical climate with intense rainfall patterns

BackgroundIn the face of escalating soil erosion exacerbated by intense rainfall in tropical climates, the quest for sustainable and effective erosion control techniques is paramount. Nature-based solutions (NbS) using bioengineering strategies have emerged as a potential avenue, yet their efficacy and adaptability in such environmental conditions are not fully explored. ObjectiveThis study seeks to bridge the research gap by evaluating the effectiveness of a bioengineering approach, which involved a strategic plantation of Pigeonpea, Sesame, and Cowpea, as an NbS for soil erosion control under the challenging conditions of tropical climates. It emphasizes the rhizospheric characteristics of these species and their potential to offer a sustainable and environmentally friendly solution to soil erosion. MethodsEmploying a random block experimental design, the study compared the performance of Pigeonpea, Sesame, and Cowpea against conventional biosynthetic erosion control methods across various plots. Over 25 rainfall events, comprehensive data collection was undertaken, encompassing 150 measures of precipitation, surface runoff, and soil loss mass. Results: The findings reveal bioengineering solution's comparable, if not superior, effectiveness to conventional techniques, marked by minimal soil loss and enhanced water infiltration capabilities. Analysis of Covariance showcased a very large effect size, significantly underscoring bioengineering's efficacy in soil loss control. Notably, bioengineering's contribution extends beyond erosion control, fostering aquifer recharge and preventing sedimentation in water bodies. ConclusionsThis strategic plantation of Pigeonpea, Sesame, and Cowpea stands out as a promising NbS for soil erosion control in tropical climates, characterized by its sustainable approach and minimal environmental footprint. The study advocates for the broader integration of Pigeonpea, Sesame, and Cowpea in soil conservation practices, highlighting its potential to transform erosion control strategies towards greater environmental sustainability and effectiveness.

CHARACTERIZING PHYSICAL STRAIN IN NON-ROUTINIZED CLINICAL WORK THROUGH OBSERVATION: AN EXAMPLE OF ORAL HEALTHCARE PROVIDERS.

The Revised Strain Index (RSI), despite its prevalence in ergonomics field practice, is designed to assess jobs with cyclic and predictable physical and behavioral patterns. The quantification of exertion force, posture, and work task duration is substantially more challenging for non-routinized work in clinical and hospital environments. Using dental hygiene work as an exemplar, we proposed a consolidated method to characterize physical exertion for non-routinized work. We conducted the RSI adaptation process in two phases. In phase one, we characterized exertion in non-routinized work and identified representative intensity and posture patterns. In phase two, we validated the consolidated method using a small subset of dental hygiene video recordings and compared the results to the conventional sampling method.

Compression and acceleration of ions by ultrashort, ultraintense azimuthally polarized light.

An efficient plasma compression scheme using azimuthally polarized light is proposed. Azimuthally polarized light possesses a donutlike intensity pattern, enabling it to compress and accelerate ions toward the optical axis across a wide range of parameters. When the light intensity reaches the relativistic regime of 10^{18}W/cm^{2}, and the plasma density is below the critical density, protons can be compressed and accelerated by the toroidal soliton formed by the light. The expansion process of the soliton can be well described by the snowplow model. Three-dimensional particle-in-cell simulations show that within the soliton regime, despite the ion density exceeding ten times the critical density, the ions' energy is insufficient for efficient neutron production. When the light intensity increases to 10^{22}W/cm^{2}, and the plasma density reaches several tens of times the critical density, deuterium ions can be compressed to thousands of times the critical density and simultaneously accelerated to the MeV level by tightly focused azimuthally polarized light during the hole-boring process. This process is far more dramatic compared to the soliton regime and can produce up to 10^{4} neutrons in a few light cycles. Moreover, in the subsequent beam-target stage, neutron yield is estimated to exceed 10^{8}. Finally, we present a comparison with the results obtained using a radially polarized light to examine the influence of light polarization.

Intensity patterns of a focused electromagnetic spherical wave with aberration

The laser pulse focused by a relativistic flying parabolic mirror can exceed the laser intensity focused by conventional physical focusing optics. Depending on the Lorentz γ-factor, the focal length of the relativistic flying mirror in the boosted frame of reference becomes much shorter than the incident beam size. The 4π-spherical focusing scheme is applied to describe such a focused field configuration. In this paper, a theoretical formalism has been developed to describe the field configuration focused by the 4π-spherical focusing scheme with an arbitrary phase error of an incident electromagnetic wave. The focused field configuration is described by the linear combination of the product of the spherical Bessel function and the spherical harmonics, resulting in the same expression as the multipole radiation. The mathematical expression showing the focused field for the femtosecond laser pulse, as well as the continuous wave, has been derived for the application to the femtosecond high-power laser. We show the three-dimensional intensity distribution near focus for the 4π-spherically focused electromagnetic field with phase error.

Ptychographic imaging with a fiber endoscope via wavelength scanning

Ptychography has become a popular computational imaging method for microscopy in recent years. In the present work we employ a wavelength scanning ptychography technique enhanced by neural networks for imaging with a fiber endoscope. Illumination of the object at various wavelengths is achieved using a single mode fiber, while a multicore fiber collects diffracted light from a distance. Using a U-Net multilayer convolutional neural network, the diffraction pattern is recovered at the far end of the multicore fiber from the recorded intensity pattern at the proximal end. With the recovered diffraction pattern in place, the phase object can be reconstructed using the ptychography algorithm. The quality of the object reconstruction improves with the number of wavelengths used. Comparison with an end-to-end neural network highlights the effectiveness and practicality of this two-step hybrid system. This alternative and simplified ptychographic endoscopy setup delivers noticeable improvements through neural networks and wavelength scanning.