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One-dimensional integrals to calculate the two-dimensional Rayleigh–Sommerfeld diffraction integrals for non-rotationally symmetric functions and general polarizing illuminating fields
摘要： The recently reported (Alcalá Ochoa, 2018) approximation to the Rayleigh–Sommerfeld diffraction integrals (RSDI) is used to obtain a set of expressions to calculate the diffraction properties of non-rotationally symmetric optical systems illuminated with polarization fields. It is proved that the three two-dimensional integrals of RSDI can be expressed accurately from two to eight one-dimensional integrals depending of the type of polarization studied. It is proved also that previous developments based on Taylor’s approximations to the RSDI can be described by these new expressions.
关键词： Imaging optics,Diffraction,Fourier optics,Physical optics,Microscopy
更新于2025-09-23 15:23:52
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Dynamic response of ferrofluidic deformable mirrors using elastomer membrane and overdrive techniques
摘要： The experimental results obtained with a ferrofluidic deformable mirror controlled by electro-magnet actuators are presented here. Using a step input through a single actuator, we obtained a steady-state settling time of 100 ms; however, different combinations of overdrive inputs can be used to decrease it to 25 ms. A new technique which consists of laying down an elastomer membrane, coated with an aluminum film, on the ferrofluid is also discussed. By adding the membrane on the ferrofluid, it further decreases the time response by a factor of 2. Furthermore, the thin aluminum layer improves the reflectivity of the mirror. Finally, using the membrane and the overdrive techniques combined, the time response is improved by a factor of 20. Numerical simulations show that ferrofluidic mirrors using membranes and improved electronics should reach settling times of the order of a millisecond. Presumably, even lower settling times could be possible.
关键词： physical optics,optical components,Adaptive optics
更新于2025-09-23 15:21:01
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The Fast Solver for Calculating the Scattered Fields from the Multiscale Scatterers
摘要： In this work, the efficient methods for calculating the scattered fields from the electrically large scatterers and multiscale scatterers are discussed. The MoM-PO method is introduced to obtain the scattered fields from the multiscale scatterers. Due to the highly oscillatory behavior of the physical optics (PO) integrals, the numerical contour deformation technique is proposed to calculate the PO scattered fields. The z buffer acceleration technique based on GPU is adopted to distinguish between the lit and shadow regions of the surfaces. Numerical examples from the electrically large and multiscale scatterers are provided to benchmark the efficiency of the proposed method.
关键词： Physical optics,parallel PO method,MoM-PO,z buffer,the TD-NSDP method,the NSDP method
更新于2025-09-19 17:15:36
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[IEEE 2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting - Atlanta, GA, USA (2019.7.7-2019.7.12)] 2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting - 2D Physical Optics Analysis of the Focal Region of Parallel-Plate Waveguide Lenses
摘要： A physical optics (PO) method for computing the focal-region fields of a parallel-plate waveguide (PPW) lens is presented. A simplified delay line model is used to represent the delay section between inner and outer lens profile. The lens is analyzed by assuming a plane wave incident on the outer contour. For a given lens geometry, the resulting maximum field loci at different angles of incidence are reported. The close agreement with full-wave results by a commercial simulator validates the applicability of the underlying two-dimensional (2D) lens model. The developed tool is several orders of magnitude faster than the general purpose full-wave simulation and therefore presents an efficient auxiliary tool for the design of lens feed networks.
关键词： parallel-plate waveguide lens,quasi-optical antennas,physical optics,beam-scanning,focal-region fields
更新于2025-09-16 10:30:52
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Fast Modeling Methods for Estimating Imaging Performance of Whole Body Screening
摘要： Simulation of millimeter wave imaging system for whole body screening before a safety inspection manufactured is a challenging work. The conventional physical optics (PO) method is a proper high-frequency approximation method to solve the forward problem of imaging. In this letter, a modi?ed PO method is used to calculate not only metal scatterer but also non-metal dielectric medium. A ray tracing (RT) method and its modi?cation are proposed to further fast estimate the performance of multiple-input-multiple-output (MIMO) imaging system. The radiation pattern of transmitter or receiver is taken into account, then the rough imaging performance of arbitrary MIMO system on arbitrary human posture can be acquired in seconds to make the system design ?exible and convenient. The image reconstruction of the proposed method for a human body model with dielectric skin medium and metal pistol has demonstrated the applicability to real-life applications.
关键词： Millimeter wave imaging,concealed weapon detection (CWD),Image reconstruction,Physical optics (PO),Ray tracing (RT),Multiple-input-multiple-output (MIMO)
更新于2025-09-10 09:29:36
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[IEEE 2018 15th European Radar Conference (EuRAD) - Madrid, Spain (2018.9.26-2018.9.28)] 2018 15th European Radar Conference (EuRAD) - Simulation of Near Field RCS to Reproduce Measurement Condition
摘要： Different approaches are presented to simulate the near field Radar Cross Section (RCS) of a perfectly conducting electrically large object. This type of environment is usually found in measurements at large anechoic chambers where the far field condition cannot be achieved, making it impossible to approximate the incident field by a planewave. Each approach will be implemented with Physical Optics (PO) for extremely large targets and an accelerated version of the Method of Moments for moderately large objects. The fast MoM method are either the Multilevel Adaptive Cross Approximation (MLACA) for an iterative solution or the Multiscale Compressed Block Decomposition (MSCBD) for a direct solution. This development and the performed simulations have been done with CAPITOLE-RCS commercial software developed by NEXIO.
关键词： physical optics,method of moments,radar cross-sections,inverse synthetic aperture radar,Numerical simulation,anechoic chambers
更新于2025-09-10 09:29:36
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Modified physical optics algorithm for near field scattering
摘要： A novel modi?ed physical optics algorithm is proposed to overcome the dif?culties of near ?eld scattering prediction for classical physical optics. The method is applied to calculating the near ?eld radar cross section of electrically large objects by taking into account the in?uence of the distinct wave propagation vector, the near ?eld Green function, and the antenna radiation pattern. By setting up local reference coordinates, each partitioned facet has its own distinct wave front curvature. The radiation gain for every surface element is taken into consideration based on the modulation of the antenna radiation pattern. The Green function is re?ned both in amplitude and phase terms and allows for near ?eld calculation. The scattered characteristics of the near ?eld targets are studied by numerical simulations. The results show that the approach can achieve a satisfactory accuracy.
关键词： physical optics,scattering,near ?eld
更新于2025-09-09 09:28:46
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Bessel beam expansion of linear focused ultrasound
摘要： Previous work on scattering by Bessel beams shows that expansion of incident sound fields in term of these beams has application to scattering [P. L. Marston, J. Acoust. Soc. Am. 122, 247–252 (2007)]. In this work, an expression for the expansion coefficients of propagating, axisymmetric, sound fields are derived. In this paper, this expression is applied to a linear focused axisymmetric sound field and is expanded in terms of Bessel beam components. This is done for focused beams radiated from a spherical cap source. A physical optics model is applied to sound propagation close to the source to facilitate the calculation of the Bessel beam expansion coefficients. This type of model is useful for focused scattering [P. L. Marston and D. S. Langley, J. Acoust. Soc. Am. 73, 1464–1475 (1983)]. Once the expansion coefficients are found, the sound field can be evaluated by superposition. The model agrees approximately with Chen, Schwarz, and Parker [J. Acoust. Soc. Am. 94, 2979–2991 (1993)] and O’Neil [J. Acoust. Soc. Am. 21, 516–526 (1949)] on axis and with direct integration of a Kirchhoff integral both on and off axis. This type of expansion will have applications to scattering problems. VC 2018 Acoustical Society of America. https://doi.org/10.1121/1.5080602
关键词： physical optics model,Kirchhoff integral,linear focused ultrasound,scattering,Bessel beam
更新于2025-09-09 09:28:46
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Sampling Rules for an Inhomogeneous Plane-wave Representation of Scattered Fields
摘要： Inhomogeneous plane waves (IPW) based on a linear contour deformation provide an accurate and concise field representation for scattering problems in which source and observation domains are visible within a limited angular sector. Given an error level, we derive closed-form expressions for the truncation limit, the sampling step and the contour slope that minimize the number of plane waves. A relation is drawn between the required number of plane waves and the degrees of freedom of the field, defined as the minimum number of orthonormal basis functions that represents scattered fields. The sampling rules are then applied to an efficient evaluation of the physical optics radiation integral.
关键词： Computational electromagnetics,spectral domain method,contour deformation,physical optics,error analysis,fast algorithm,degrees of freedom,field representation,Green’s function,scattering,inhomogeneous plane waves
更新于2025-09-09 09:28:46
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RECTANGULAR WAVE BEAM BASED GO/PO METHOD FOR RCS SIMULATION OF COMPLEX TARGET
摘要： The rectangular wave beams-based geometrical optics (GO) and physical optics (PO) hybrid method is applied to the radar cross section (RCS) simulation of complex target. In the implementation process, the incident wave beam is divided into plenty of regular rectangular wave beams. The RCS of target is subsequently harvested from the sum of the contributions from rectangular wave beams. And Open Graphics Library (OpenGL) is used to accelerate ray tracing for the GO/PO method. Here, each pixel corresponds to a rectangular wave beam, which improves the defect that the pixel number should be larger than the patch number on the model and the e?ciency in the general OpenGL based GO/PO method. In addition, the patch size in the presented method can be arbitrary as long as the model is described accurately with these patches. The simulation results prove this point and show that the proposed rectangular wave beam-based GO/PO method is feasible and can keep a high calculation accuracy and e?ciency with a low pixel number.
关键词： ray tracing,geometrical optics,OpenGL,rectangular wave beams,radar cross section,physical optics
更新于2025-09-04 15:30:14