{"title":"Phase-restoring subpixel image registration: enhancing motion detection performance in Fourier-domain optical coherence tomography.","authors":"Huakun Li, Bingyao Tan, Vimal Prabhu Pandiyan, Veluchamy Amutha Barathi, Ramkumar Sabesan, Leopold Schmetterer, Tong Ling","doi":"10.1088/1361-6463/adb3b4","DOIUrl":"10.1088/1361-6463/adb3b4","url":null,"abstract":"<p><p>Phase-sensitive Fourier-domain optical coherence tomography (FD-OCT) enables <i>in-vivo</i>, label-free imaging of cellular movements with detection sensitivity down to the nanometer scale, and it is widely employed in emerging functional imaging modalities, such as optoretinography (ORG), Doppler OCT, and optical coherence elastography. However, when imaging tissue dynamics <i>in vivo</i>, inter-frame displacement introduces decorrelation noise that compromises motion detection performance, particularly in terms of sensitivity and accuracy. Here, we demonstrate that the displacement-related decorrelation noise in FD-OCT can be accurately corrected by restoring the initial sampling points using our proposed Phase-Restoring Subpixel Image Registration (PRESIR) method. Derived from a general FD-OCT model, the PRESIR method enables translational shifting of complex-valued OCT images over arbitrary displacements with subpixel precision, while accurately restoring phase components. Unlike conventional approaches that shift OCT images either in the spatial domain at the pixel level or in the spatial frequency domain for subpixel correction, our method reconstructs OCT images by correcting axial displacement in the spectral domain (k domain) and lateral displacement in the spatial frequency domain. We validated the PRESIR method through simulations, phantom experiments, and <i>in-vivo</i> ORG in both rodents and human subjects. Our approach significantly reduced decorrelation noise during the imaging of moving samples, achieving phase sensitivity close to the fundamental limit determined by the signal-to-noise ratio.</p>","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"58 14","pages":"145102"},"PeriodicalIF":3.1,"publicationDate":"2025-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11843479/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143482086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Recent progresses and applications on chiroptical metamaterials: a review","authors":"Yan Wang, Zeyu Wu, Wenming Yu and Zhengqi Liu","doi":"10.1088/1361-6463/ad6f20","DOIUrl":"https://doi.org/10.1088/1361-6463/ad6f20","url":null,"abstract":"Chiroptical metamaterials have attracted considerable attention owing to their exciting opportunities for fundamental research and practical applications over the past 20 years. Through practical designs, the chiroptical response of chiral metamaterials can be several orders of magnitude higher than that of natural chiral materials. Chiroptical metamaterials therefore represent a special type of artificial structures for unique chiroptical activities. In this review, we present a comprehensive overview of the progresses in the development of chiroptical metamaterials. Chiroptical metamaterial progress enables applications, including asymmetric transmission, polarization conversion, chiral absorber, chiral imaging, chiral sensor and chiral emission. We also review fabrication techniques and design of chiroptical metamaterials based on deep learning. In the conclusion, we present possible further research directions in this field.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"27 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Guobao Zhang, Wei Yang, Lei Zhang, Zhengyang Wu, Mengyi Cai, Taiyun Zhu, Lei Sun, He Gao and Zhen Li
{"title":"Electrical surface breakdown characteristics of micro- and nano-Al2O3 particle co-doped epoxy composites","authors":"Guobao Zhang, Wei Yang, Lei Zhang, Zhengyang Wu, Mengyi Cai, Taiyun Zhu, Lei Sun, He Gao and Zhen Li","doi":"10.1088/1361-6463/ad773e","DOIUrl":"https://doi.org/10.1088/1361-6463/ad773e","url":null,"abstract":"Epoxy microcomposites are basic materials for gas-insulated switchgear (GIS) spacers that are subjected to huge electrical stress. Previous works have indicated that nanoparticles are beneficial to dielectric performance. However, surface electrical breakdown, a typical fault in GIS of co-doped micro- and nanoparticles in epoxy composites, is seldom studied. In this work, numerous concentrations of micro- and nano-Al2O3 are co-doped into an epoxy matrix; the surface traps, surface charging, and surface breakdown voltages (Vsb) of the co-doped composites are studied, and the influence of micro- and nano-Al2O3 on the electrical surface breakdown is clarified. The results show that Vsb first decreases and then increases with the microparticles, and Vsb decreases from 25.34 kV to 19.52 kV. As the number of nanoparticles increases, Vsb increases and then decreases when the microparticle loading is low, but decreases and then increases when the microparticle loading exceeds 40 wt%. Micro-Al2O3 particles introduce surface shallow traps into epoxy composites, while small amounts of nano-Al2O3 introduce deep traps. Two different mechanisms dominate the surface charging and Vsb of epoxy micro-nanocomposites. When the surface conductivity is lower than 7 × 10−14 S, the surface charges are reduced by the suppression of electrode injection as the trap depth increases, and Vsb increases. When the surface conductivity exceeds 7 × 10−14 S, the surface charge dissipation rate increases with the surface conductivity and Vsb increases as the surface conductivity increases. Our work indicates that co-doped micro- and nano-particles should keep the surface conductivity away from the specic value (7 × 10−14 S) to safeguard insulation properties for GIS spacers.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"19 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marek Šťastný, Kryštof Mrózek, Karel Juřík, Lukáš Havlíček, Michal Novotný and Adam Obrusník
{"title":"Numerical simulations of a low-pressure electrodeless ion source intended for air-breathing electric propulsion","authors":"Marek Šťastný, Kryštof Mrózek, Karel Juřík, Lukáš Havlíček, Michal Novotný and Adam Obrusník","doi":"10.1088/1361-6463/ad7471","DOIUrl":"https://doi.org/10.1088/1361-6463/ad7471","url":null,"abstract":"Air breathing electric propulsion (ABEP) systems offer a promising solution to extend the lifetime of very low earth orbit (VLEO) missions by using residual atmospheric particles as propellants. Such systems would operate in very low-pressure environments where plasma ignition and confinement prove challenging. In this contribution, we present results of a global plasma model (GPM) of a plasma ignited in a very low-pressure air mixture. The results are validated against experimental measurements acquired using a laboratory electrodeless ion source utilizing a resonator for plasma ignition. The device is specifically designed to operate within low-pressure environments as it holds potential applications in ABEP systems for VLEO missions. Parametric studies are carried out via GPM to investigate the resonant behavior and its implications. The potential of the model serving as a predictive tool is assessed through experimental validation against measured data, mainly investigating the extracted ion current dependency on operational pressure and external magnetic field strength. The verified model is further utilized to extrapolate additional information about the resonant plasma such as ion composition or a degree of ionization.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"66 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Oxygen vacancies kinetics in TaO 2 − ...","authors":"C Ferreyra, R Leal Martir, D Rubi and M J Sánchez","doi":"10.1088/1361-6463/ad7155","DOIUrl":"https://doi.org/10.1088/1361-6463/ad7155","url":null,"abstract":"Oxygen vacancies (OV) are pervasive in metal oxides and play a pivotal role in the switching behaviour of oxide-based memristive devices. In this study we address OV dynamics in Pt/TaO /Ta2O /TaO /Pt devices, through a combination of experiments and theoretical simulations, In particular, we focus on the RESET transition (from low to high resistance) induced by the application of electrical pulse(s), by choosing different initial OV profiles and studying their kinetics during the mentioned process. We demonstrate that by selecting specific OV profiles it is possible to tune the characteristic time-scale of the RESET. Finally, we show that the implementation of gradual RESETs, induced by applying many (small) successive pulses, allows estimating the activation energies involved in the OV electromigration process. Our results help paving the way for OV engineering aiming at optimizing key memristive figures such as switching speed or power consumption, which are highly relevant for neuromorphic or in-memory computing implementations.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"48 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhinan Luo, Xiaoxiao Ding, Jie Yang, Yuhan Wu, Bichao Wang, Ling Miao, Shaowei Bie and Jianjun Jiang
{"title":"Dispersion compensation design of high-density stacking RFSS absorbers for wideband applications","authors":"Zhinan Luo, Xiaoxiao Ding, Jie Yang, Yuhan Wu, Bichao Wang, Ling Miao, Shaowei Bie and Jianjun Jiang","doi":"10.1088/1361-6463/ad7511","DOIUrl":"https://doi.org/10.1088/1361-6463/ad7511","url":null,"abstract":"A dispersion compensation design absorber realized by high-density stacking resistive frequency selective surface (RFSS) is proposed for wideband applications. Firstly, the quantitative relationship between the equivalent impedance of RFSS and the permittivity of the effective media is constructed with the help of the transmission matrix method. The dispersion regulation of permittivity is achieved by changing the pattern and the square resistance of RFSS. In terms of absorber design, a uniform absorber with dispersion manipulation is developed as a precursor absorber. The uniform absorber has an absorption performance better than −8.5 dB above 2 GHz at normal incidence. The loss mechanism is analyzed in detail by electric field distribution and surface power loss density distribution, indicating that the uniform design cannot achieve thickness saving when extending to low frequency. Therefore, a dispersion compensation design absorber is proposed to extend −10 dB bandwidth to 1.64–28.8 GHz. Experiment results agree well with the simulation results, validating the analytic methods and design principles.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"18 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E Serquen, F Bravo, Z Chi, L A Enrique, K Lizárraga, C Sartel, E Chikoidze and J A Guerra
{"title":"Impact of c- and m- sapphire plane orientations on the structural and electrical properties of β-Ga2O3 thin films grown by metal-organic chemical vapor deposition","authors":"E Serquen, F Bravo, Z Chi, L A Enrique, K Lizárraga, C Sartel, E Chikoidze and J A Guerra","doi":"10.1088/1361-6463/ad76bb","DOIUrl":"https://doi.org/10.1088/1361-6463/ad76bb","url":null,"abstract":"This work presents a comprehensive investigation into the structural and electrical properties of Ga2O3 thin films grown via metal-organic chemical vapor deposition on both c- and m-plane sapphire substrates. Structural characterization revealed the β-Ga2O3 phase formation in both substrate orientations, with strong epitaxial preferential growth on c-plane substrates and polycrystalline films on m-plane substrates. Results show that Ga2O3/m-sapphire exhibits the lower electrical resistivity than its counterpart grown on c-sapphire. Activation energies of acceptor levels were estimated at ~1.4 and ~0.7 , for Ga2O3 films grown on c- and m-plane, respectively. This result shows that growing Ga2O3 on m-plane sapphire is beneficial to reach a weakly compensated sample. Cathodoluminescence analysis suggests that the additional low activation energy of ~0.18 observed in Ga2O3 grown with the highest oxygen flow on m-plane sapphire can be associated to thermally-induced migration of self-trapped hole states.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"214 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Subrata Ghosh, Giacomo Pagani, Massimilano Righi, Chengxi Hou, Valeria Russo and Carlo S Casari
{"title":"One-step pulsed laser deposition of carbon/metal oxynitride composites for supercapacitor application","authors":"Subrata Ghosh, Giacomo Pagani, Massimilano Righi, Chengxi Hou, Valeria Russo and Carlo S Casari","doi":"10.1088/1361-6463/ad76bc","DOIUrl":"https://doi.org/10.1088/1361-6463/ad76bc","url":null,"abstract":"Advanced material composite of nanocarbons and metal-based materials provides a synergistic effect to obtain excellent electrochemical charge-storage performance and other properties. Herein, 3D porous carbon-metal oxynitride nanocomposites with tunable carbon/metal and oxygen/nitrogen ratio are synthesized uniquely by simultaneous ablation from two different targets by single-step pulsed laser deposition at room temperature. Co-ablation of titanium and vanadium nitride targets together with graphite allowed us to synthesize carbon-metal oxynitride porous nanocomposite and exploit them as a binder-free thin film supercapacitor electrode in aqueous electrolyte. We show that the elemental composition ratio and hence the structural properties can be tuned by selecting target configuration and by manipulating the ablation position. We investigate how this tuning capability impacts their charge-storage performances. We anticipate the utilization of as-synthesized various composites in a single PLD production run as next-generation active materials for flexible energy storage and optoelectronic applications.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"92 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Design of systems for plasma activated water (PAW) for agri-food applications","authors":"N N Misra, Tejas Naladala and Khalid J Alzahrani","doi":"10.1088/1361-6463/ad77de","DOIUrl":"https://doi.org/10.1088/1361-6463/ad77de","url":null,"abstract":"This review explores the engineering and design aspects of plasma activated water (PAW) systems, focusing on their application in food safety and agriculture. This review aims to bridge the gap between research and practical application, paving the way for the development of robust and efficient PAW systems for enhancing food safety and agricultural productivity. By examining a variety of activation methods, including direct gas ionization, underwater discharges, and dynamic interactions of ionized gases with liquids, this work discusses the mechanical designs that facilitate these processes, highlighting their scalability and efficiency. The discussion is grounded in a comprehensive relevant scientific and patent literature, offering a critical overview of the systems’ design parameters that influence the generation of reactive oxygen and nitrogen species (RONS). The designs reported in literature have employed three major approaches, viz. direct underwater discharges, gas ionization followed by introduction of plasma into the liquid, creation of gas liquid mixtures and subsequent ionization. The laboratory systems have relied on natural convective diffusion of the RONS into water, while most of the patents advocate use of forced convective diffusion of RONS to increase transfer rates. Despite widespread laboratory-scale research in PAW, the transition to industrial-scale systems remains underexplored.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"30 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Wide-angle reflection control with a reflective digital coding metasurface for 5G communication systems","authors":"Zhihao Mao, Da Li and Er-Ping Li","doi":"10.1088/1361-6463/ad7510","DOIUrl":"https://doi.org/10.1088/1361-6463/ad7510","url":null,"abstract":"Metasurfaces have attracted widespread attention in recent years due to their powerful electromagnetic wave manipulation capabilities. This paper proposes and validates a single-polarized, angle-adjustable reflective digital coding metasurface. Each unit cell achieves independent reflection phase control by loading a PIN diode for on-off switching. The unit’s design and coding scheme are carefully optimized to ensure the performance of the proposed reconfigurable metasurface. As a validation, a prototype consisting of 16×16 elements is fabricated and measured, with a control signal provided by a field-programmable gate array controller. Experimental results demonstrate angle control of up to ±60° in the frequency range of 3.4 GHz–3.6 GHz, a peak gain of 24.9 dBi in a single channel, and gain exceeding 10 dBi across a 200 MHz operational bandwidth. Furthermore, the performance is validated in a communication system, yielding positive results. The proposed reflective digital coding metasurface contributes to the advancement of reconfigurable intelligent surfaces and holds promise for widespread adoption in various communication scenarios.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"118 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}