- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Profiles of RFI in Alos-2 Images - A Case Study in Tokyo Bay, Japan
摘要： Synthetic aperture radar (SAR) shares its radio frequency with the other systems and thus, inevitably receives their signals. Such cross-talk, radio frequency interference (RFI) has been traditionally eliminated by spectrum filters. However, a latest L-band SAR, ALOS-2, receives frequency modulated wideband signals that cannot be detected by traditional spectrum filters. These RFIs have the same or wider bandwidth than SAR and thus, appears in SAR images. They also interrupt interferometric (InSAR) and polarimetric (PolSAR) analysis because it appears in every observations and in full-polarimetric mode images. We report the investigation results of the profiles of such RFI in Tokyo bay, Japan.
关键词： Radio Frequency Interference,PALSAR-2,ALOS-2,Polarimetry,Interferometry
更新于2025-09-23 15:21:21
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Forest Height Estimation Using Adaptive Decomposition Method of Polinsar Data
摘要： In this paper, we present an approach to retrieve forest height using an adaptive scattering model decomposition technique with PolInSAR data. This method combines the adaptive scattering model decomposition technique and the coherence amplitude method. This procedure enables the retrieval not only of the vegetation parameters but also of the magnitude associated with each mechanism. To test the performance of the proposed method ESAR PolInSAR L band data of Oberpfaffenhofen, in Germany is used to show the accuracy of the forest height estimation.
关键词： interferometry,Model-based decomposition,polarimetry,forest height estimation
更新于2025-09-23 15:21:21
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Added Value of Multitemporal Polarimetric UAVSAR Data for Permanent Scatterers Detection
摘要： In the last decades, differential synthetic aperture radar (SAR) interferometric (InSAR) (DInSAR) techniques have been used to estimate the Earth’s surface deformation with high resolution. In this paper, we present an approach for increasing the quantity of permanent scattered pixels. These pixels are selected for DInSAR processing based on polarimetric information prepared by new sensors. The objective of this paper is then to test existing algorithms that confirm the contribution of polarimetric data for improving persistent scatterers (PS) detection. These algorithms are formulated based on two different selection criteria: amplitude dispersion index and mean coherence. Different approaches are analyzed to optimize both selection criteria in terms of pixels’ quantity and density and finally their results are quantitatively compared. Experimental results with exploiting quad-pol UAVSAR dataset over an urban area in CA, provide the expected improvement. Comparing the number of PSs between quad-pol with dual-pol and single-pol cases illustrate remarkable improvement in both selection criteria. For quad-pol case, we achieve an increase of 50% and 60% with respect to dual-pol and single-pol data, respectively, when using average coherence and over 6 times more for amplitude dispersion index. The results of our study demonstrates the added value of polarimetric SAR observations (dual pol and quad-pol) for improved permanent scatterers detection monitored areas.
关键词： Polarimetry,particle swarm optimization,Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR),Permanent Scatterer
更新于2025-09-23 15:21:21
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - THz Quantum Cascade Lasers with Optimized Beam Divergence
摘要： Huynen decomposition (HD) as the first formalized target decomposition has not been widely accepted. The preference for symmetry and regularity restricts not only its application but also its unification with other target dichotomies. The nonuniqueness issue then arises because we may have different dichotomies of radar targets, but we have no idea on how to select them. In this paper, a unified Huynen dichotomy is developed by extending HD for a full preference for symmetry and regularity, nonsymmetry, irregularity, and their couplings. It covers all of the existing dichotomies and provides a unified selection mechanism for them. Scattering preference is identified as a main feature of target dichotomy, and its concise description is devised by relating each dichotomy to a canonical scattering. A scattering degree of preference (SDoP) parameter is defined to measure the preference of each dichotomy. In virtue of an adaptive combination and permutation of SDoPs, a scattering pyramid description of the mixed scattering is developed, which has better discrimination of target than entropy/alpha. An SDoP/alpha classification is further proposed by statistical modeling of the unified dichotomy, which is a competent alternative to entropy/alpha. The excellent performance of unified dichotomy makes us believe that the existing concerns on HD are well treated and the Huynen–Cloude controversy, in a sense, may be ended.
关键词： target extraction,target decomposition,unsupervised classification,Huynen decomposition (HD),radar polarimetry
更新于2025-09-23 15:21:01
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The role of the femtosecond laser induced nano/micro structures on the optical features of the steel surface; experimental polarimetry study
摘要： We are witnessing that ultrashort laser material processing (ULMP) is getting an established technique to modify many characteristics of a surface. Being applicable for various materials with any geometry or physical characteristics, besides being rapid and having simple experimental set-ups makes ULMP appropriate for small and large scale controlled modifications. Using this method to adjust the optical features of a surface has been also suggested in last years. So that mimicking the functional surfaces existing in nature which have distinctive surface morphologies and thus have special optical features, efforts are going on to create similar samples using ULMP. Here in this study, the potential of ULMP technique in changing the optical properties of metallic substrates is explored. Selecting 316L stainless steel as a substrate, five samples which are irradiated in different circumstances are fabricated. The role of the laser induced nano/micro structures on the optical features of these samples are studied systematically. Visible light backscattering in the range of 0°-65° was studied at first. Extracting the Mueller matrix elements for all samples at two different incident angles of 45° and 60°, the polarimetry parameters including retardancy, depolarization and diattenuation are calculated at the next step. Due to the multi-scale nature of the morphologies, more than the illuminating light angle, dependence of the samples optical response to its orientation is also discussed in detail Results clearly reflect that the optical response of laser induced periodic surface structure (LIPSS) coated layers have an anisotropic behavior regarding the incident angle and the polarization of the illuminating light. Furthermore, the surface orientation itself can play very serious role on the final response of the sample. It comes out that the characteristics of a surface such as its morphology, roughness or the correlation of the LIPSS structures has important effect in these regards.
关键词： backscattering,structure,femtosecond laser,surface,optical features,polarimetry
更新于2025-09-23 15:21:01
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Generalized Hartmann-Shack array of dielectric metalens sub-arrays for polarimetric beam profiling
摘要： To define and characterize optical systems, obtaining the amplitude, phase, and polarization profile of optical beams is of utmost importance. Traditional polarimetry is well established to characterize the polarization state. Recently, metasurfaces have successfully been introduced as compact optical components. Here, we take the metasurface concept to the system level by realizing arrays of metalenses, allowing the determination of the polarization profile of an optical beam. We use silicon-based metalenses with a numerical aperture of 0.32 and a mean measured focusing efficiency in transmission mode of 28% at a wavelength of 1550 nm. Our system is extremely compact and allows for real-time beam diagnostics by inspecting the foci amplitudes. By further analyzing the foci displacements in the spirit of a Hartmann-Shack wavefront sensor, we can simultaneously detect phase-gradient profiles. As application examples, we diagnose the profiles of a radially polarized beam, an azimuthally polarized beam, and of a vortex beam.
关键词： metasurfaces,metalens,beam profiling,polarimetry,Hartmann-Shack array
更新于2025-09-23 15:21:01
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Prediction of the Suna??s Coronal Magnetic Field and Forward-modeled Polarization Characteristics for the 2019 July 2 Total Solar Eclipse
摘要： On 2019 July 2 a total solar eclipse—visible across parts of the Southern Pacific Ocean, Chile, and Argentina—enabled observations of the Sun’s corona. The structure and emission characteristics of the corona are determined by underlying magnetic fields, which also govern coronal heating and solar eruptive events. However, coronal magnetic field measurements remain an outstanding challenge. Coronal magnetic field models serve an important purpose in this context. Earlier work has demonstrated that the large-scale coronal structure is governed by surface flux evolution and memory buildup, which allows for its prediction on solar rotational timescales. Utilizing this idea and based upon a 51 day forward run of a predictive solar surface flux transport model and a potential field source surface model, we predict the coronal structure of the 2019 July 2 solar eclipse. We also forward model the polarization characteristics of the coronal emission. Our prediction of two large-scale streamer structures and their locations on the east and west limbs of the Sun match eclipse observations reasonably well. We demonstrate that the Sun’s polar fields strongly influence the modeled corona, concluding that accurate polar field observations are critical. This study is relevant for coronal magnetometry initiatives envisaged with the Daniel K. Inouye Solar Telescope, Coronal Multichannel Polarimeter and upcoming space-based instruments such as Solar Orbiter, Solar Ultraviolet Imaging Telescope and the Variable Emission Line Coronagraph on board the Indian Space Research Organisation’s Aditya-L1 space mission.
关键词： Solar magnetic fields,Magnetohydrodynamics,Polarimetry,Solar corona,Solar eclipses
更新于2025-09-23 15:19:57
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[IEEE 2019 9th International Electric Drives Production Conference (EDPC) - Esslingen, Germany (2019.12.3-2019.12.4)] 2019 9th International Electric Drives Production Conference (EDPC) - Evaluation of Soft Magnetic Ferrosilicon FeSi 6.5 for Laser Beam Melting
摘要： Planar or cylindrical phased arrays are two candidate antennas for future polarimetric weather radar. These two candidate antennas have distinctly different attributes when used to make quantitative measurements of the polarimetric properties of precipitation. Of critical concern is meeting the required polarimetric performance for all directions of the electronically steered beam. The copolar and cross-polar radiation patterns and polarimetric parameter estimation performances of these two phased array antennas are studied and compared with that obtained using a dual-polarized parabolic reflector antenna. Results obtained from simulation show that the planar polarimetric phased array radar has unacceptable polarimetric parameter biases that require beam to beam correction, whereas biases obtained with the cylindrical polarimetric phased array radar are much lower and comparable to that obtained using the parabolic reflector antenna.
关键词： radiation patterns,phased array radar,cylindrical array,Antenna,polarimetry,planar array,remote sensing,weather measurement
更新于2025-09-23 15:19:57
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[IEEE 2019 International Workshop on Fiber Optics in Access Networks (FOAN) - Sarajevo, Bosnia and Herzegovina (2019.9.2-2019.9.4)] 2019 International Workshop on Fiber Optics in Access Networks (FOAN) - Degradation of Optical Fiber Parameters During the Period of Usage: 2003 - 2019
摘要： Change detection using synthetic aperture radar (SAR) data is useful in emergency situations and unfavorable weather conditions. In this letter, change detection using multitemporal polarimetric Uninhabited Aerial Vehicle SAR data is investigated in an urban environment. The most robust polarimetric parameters are determined, and change detection techniques using a maximum likelihood ratio and a hyperbolic tangent model function are applied to the selected parameter. The model function was introduced to quantify the change characteristics and to rule out seasonal changes or those related to mobile features, and thus to only detect durable and permanent changes in urban environments. A comparison of results with historical Google Earth images showed a good level of agreement. Fitting of the hyperbolic tangent function to the multitemporal polarimetric parameters significantly reduces the false detection rate and indicates whether a building was constructed or destroyed, as well as when the detected changes occurred.
关键词： Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR),Change detection,polarimetry,multitemporal,urban
更新于2025-09-23 15:19:57
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[IEEE 2019 International Conference on Electrical, Electronics and Computer Engineering (UPCON) - ALIGARH, India (2019.11.8-2019.11.10)] 2019 International Conference on Electrical, Electronics and Computer Engineering (UPCON) - Performance Optimization of p-n Junction Solar cells with Device Architecture
摘要： Huynen decomposition (HD) as the first formalized target decomposition has not been widely accepted. The preference for symmetry and regularity restricts not only its application but also its unification with other target dichotomies. The nonuniqueness issue then arises because we may have different dichotomies of radar targets, but we have no idea on how to select them. In this paper, a unified Huynen dichotomy is developed by extending HD for a full preference for symmetry and regularity, nonsymmetry, irregularity, and their couplings. It covers all of the existing dichotomies and provides a unified selection mechanism for them. Scattering preference is identified as a main feature of target dichotomy, and its concise description is devised by relating each dichotomy to a canonical scattering. A scattering degree of preference (SDoP) parameter is defined to measure the preference of each dichotomy. In virtue of an adaptive combination and permutation of SDoPs, a scattering pyramid description of the mixed scattering is developed, which has better discrimination of target than entropy/alpha. An SDoP/alpha classification is further proposed by statistical modeling of the unified dichotomy, which is a competent alternative to entropy/alpha. The excellent performance of unified dichotomy makes us believe that the existing concerns on HD are well treated and the Huynen–Cloude controversy, in a sense, may be ended.
关键词： target decomposition,Huynen decomposition (HD),unsupervised classification,target extraction,radar polarimetry
更新于2025-09-23 15:19:57