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The axial resolution of conventional confocal microscopy is usually larger than 600 nm. In super-resolution microscopy, although Stimulated emission depletion (STED) microscopy offers lateral resolution beyond the optical diffraction limit [1, 2], the axial resolution often remains the same, unless a special set of phase modulation is employed. With two opposing objectives in 4Pi microscopy, the interference...
Super-resolution microscopy such as STED [1, 2], SSIM [3], or PALM/STORM [4] placed their respective critical requirements on the fluorescent labeling, thereby limits their applications in biology. Polarization as the fourth dimension of fluorescence can also provide intensity modulation, yet without the restriction to specific fluorophores. Here we present a new technique termed super-resolution...
Whether targets can be easily and precisely recognized is becoming a significant criterion on measuring the performance of radar. During the process of radar imaging, this criterion is always affected by the extent of sidelobe suppression. Currently, the methods of sidelobe suppression are over-studied and effective but it also owns some various shortages. In order to promote the technique of sidelobe...
Various modern SAR systems are equipped with phase array antennas and can change the squint angle during the data acquisition. With such Doppler drifts, several advanced SAR modes, like, e.g. spotlight and TOPS are possible. However, such operations cause additional problems for the interferometric processing of the data. The Doppler drift needs to be accounted for in filtering and resampling to avoid...
This paper proposed a novel method of three-dimensional (3D) imaging based on orthogonal-track ground-based arc synthetic aperture radar (GB-SAR). In the scheme, the SAR sensor moves along two orthogonal arc tracks successively and two SAR images are obtained. Then spacial information of the two dimensional (2D) SAR images are extracted to reconstruct the 3D distribution of scatterers in the common...
This paper introduces an extended factorized geometrical autofocus (FGA) algorithm for circular synthetic aperture radar (CSAR) which is based on the FGA in stripmap synthetic aperture radar (SAR). The strategy is that integrate the FGA with a fast factorized back-projection (FFBP) processing chain and relies on varying track parameters step by step to obtain the sharp image. The focused quality of...
For sparse Radar signals, sparse imaging method is subversion of the traditional imaging method, which breaks through the limitations existing in traditional imaging method. In order to improve the imaging quality of Radar signals, we don't only realize the sparse radar imaging algorithm, but also propose a new method for choosing regularization parameter in 2D radar imaging. The imaging result verifies...
In order to extract the horizontal synchronization information of stochastic video signal and reconstruct video image stably and automatically, the computer video signal captured from the video cable will be analyzed and the method of correlation of stochastic video signal is put forward in this paper. Without synchronization information and resolution information of the monitors, the video images...
A switch uniform linear array (ULA) frequency-modulated continuous-wave (FMCW) synthetic aperture radar (SAR) system transmits and receives FMCW waveform by firing elements of the ULA sequentially under the control of a switch network. Resolution in range is achieved by range compression and in ULA direction is achieved by digital beamforming. Compared with a conventional SAR system, a switch ULA...
We propose and demonstrate a new class of all-dielectric metamaterial superlens constructed from 3D assembly of high-index nanoparticles (TiO2, ZrO2, Si). The fundamental physics lies in the unusual high efficiency of direct conversion of evanescent waves into propagation waves by the composite media. In Figure 1(a) 3D full wave FDTD simulation was presented for a conventional homogenous material...
Here we show a method of color printing on nanoimprinted plasmonic metasurfaces [1] using laser post-writing. Laser pulses induce transient local heat generation that leads to melting and reshaping of the imprinted nanostructures [2]. This leads to melting and reshaping of the imprinted 20nm Al structures embedded in plastics. Depending on the laser pulse energy density, different surface morphologies...
It is hard to choose one appropriate sparse reconstruction algorithm from multiple existing algorithms in different occasions. Being aware of this difficulty, four typical sparse reconstruction algorithms are studied to present comprehensive performance evaluations in terms of reconstruction accuracy, super-resolution ability and noise immunity, and it is found that the BCS algorithm performs best...
Electromagnetic time-reversal enabling potential super-resolution in telecommunication systems when operated within complex media — imaging is left aside from now — has been much studied, in particular since [1]. Yet it remains a controversial issue [2]. Here, one illustrates what could be the behavior of a radiating broad-frequency device when operated in a properly-structured, finitely-extended...
For the conventional Inverse synthetic aperture radar (ISAR) imaging, the observation durations must be long enough to achieve high cross-range resolution. However, it is often impossible to achieve enough echo samples in cross-range, making the imaging result with poor resolution. Compressed sensing (CS) is a new approach of sparse signals recovered. In this paper, a high resolution ISAR imaging...
Corner reflector is a metal equipment consisting of three mutually perpendicular planes. It is widely used in radiometric calibration as well as an ideal point. Earlier researchers usually regard it as an isotropic target for synthetic aperture radar (SAR) applications. However, deep analysis indicates imaging characteristics of a corner reflector vary with azimuth observation angle. With the increasing...
Nanoscale local field sensing is a powerful technique for various applications in physical and biological studies. The performance critically depends on the high spatial resolving capability. Conventional protocols mainly make use of the scanning pointed tips with near field interaction, while the tips would introduce perturbation to the detected field at nanoscale and. Also the preparation of tips...
Optical microscopy is one of the most important scientific achievements in the history of mankind, and it is the most widely used technique for exploring the small world. However, as is well known, traditional lens-based optical microscopes suffer from the low imaging resolution λ/2 due to the diffraction limit. To overcome this obstacle, multiple innovative methods have been proposed during the past...
Namco lake is the second largest lake on the Tibetan Plateau as well as the highest large lake in the world, which is located in the south central Tibetan Plateau, with a total area of 2020.66km2 and a total catchment area of 10,680km2. The usefulness of traditional optical images highly depends on cloudless weather conditions and suitable solar illumination, while lake area detection procedures in...
Millimeter wave Near-field 3-D imaging has great importance on security applications for its penetrating characteristics and the 3-D information of the target. To obtain accurate and high resolution images, we propose a direct 3-D integral method to reconstruct the 3-D images. The algorithm directly processes the scattered data without any interpolation or approximation, making it more accurate than...
The development of stealth technology and anti-stealth technology relies on the research of targets electromagnetic scattering characteristics. The electromagnetic scattering characteristics of complex targets vary from different electromagnetic environment. Broad band and variable polarization technology are combined in this paper to obtain more detailed information of the targets, including high...
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