Orbital angular momentum (OAM) provides a new high-dimensional degree-of-freedom for lasers enabling high-dimensional shift keying, thus showing huge potential in free-space optical data-transmissions. Ensuring the ac...
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A dual-band broadband conical beam antenna operating at Ku-/ Ka-band is presented in this paper. The proposed antenna adopts a novel across-layer folded structure which consists of two substrates. A circular patch wit...
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Optical skyrmions, a type of topologically protected quasiparticle, have undergone various deformations in recent years. In this Letter, we present a scheme that can achieve the selective formation of generalized opti...
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Dielectric laser accelerators (DLAs) can achieve acceleration gradients that are 1 to 2 orders of magnitude higher than traditional radiofrequency (RF) accelerators. Due to the micrometer-scale dimensions of the DLA a...
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ISBN:
(纸本)9781510682160
Dielectric laser accelerators (DLAs) can achieve acceleration gradients that are 1 to 2 orders of magnitude higher than traditional radiofrequency (RF) accelerators. Due to the micrometer-scale dimensions of the DLA acceleration structure, on the one hand, high requirements are imposed on the quality of the electron beam and the alignment among the electron beam, driving laser, and DLA in experiments. On the other hand, although the DLA acceleration gradient is very high, the acceleration distance is insufficient, resulting in relatively small absolute energy gain for sub-relativistic electrons after DLA acceleration. These electrons are susceptible to interference from stray electromagnetic fields during propagation, posing significant challenges to the resolution and accuracy of sub-relativistic electron energy spectrum testing. Based on the principle of laser-driven grating-structure DLA for accelerating electron beams, this paper designs a complete test system, constructs electronic dynamics simulation models and magnetic field measurement electron energy spectrum simulation models for verification, designs a double-layer magnetic shunt to shield the interference of leakage magnetic fields on electrons in the simulation, considers factors such as the beam spot radius, divergence angle, and geomagnetic field intensity of the electron beam that conform to experimental conditions, and finally obtains simulated images of electron spots on the fluorescent screen after the electron beam is deflected by the magnetic field. The electron dynamics simulation results show that the electron beam achieves a maximum energy gain of 14.4401 keV over an acceleration length of 36 μm, with an acceleration gradient reaching 401.114 MeV/m. Based on the acceleration effect, a magnetic field of BB = 170 Gs is set, and an electron spot after deflection is obtained. The edges of the spots before and after acceleration are separated by Δd = 4.2889 mm, and the maximum energy gain measurem
Ground Penetrating Radar (GPR) technology is a widely used detectiontechnology for underground target objects, which can perform non-destructive detection of underground targets. Due to the complexity of the undergro...
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Spatiotemporal compressed imaging(STCI) aims to improve the spatial and temporal resolution of an imaging system simultaneously, which can effectively alleviate the mutual constraints between the two imaging resolutio...
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Traditional computer vision tasks rely on high-quality images for classification, but single-pixel imaging (SPI) uses compressive sensing with a bucket detector to simplify hardware and reduce costs. However, factors ...
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Depth information is an important tool in the computer vision field for object detection, recognition, and 3D modeling. Conventional depth sensors have a limited field of view(FOV) and provide limited depth informatio...
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Optical varifocal systems have extensive applications such as consumer electronics, defense equipment, industrial monitoring, and medical devices. Traditional varifocal methods typically involve multiple lenses and me...
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ISBN:
(数字)9781510688155
ISBN:
(纸本)9781510688148
Optical varifocal systems have extensive applications such as consumer electronics, defense equipment, industrial monitoring, and medical devices. Traditional varifocal methods typically involve multiple lenses and mechanical components. The lenses often move along the optical axis using motors to achieve the varifocal ability. This configuration introduces some limitations, such as more structural complexity, larger size, slower varifocal speed, and higher production cost. Different from the traditional varifocal lenses, Alvarez lenses comprise two symmetrically arranged freeform surface phase plates moving perpendicular to the optical axis. The Alvarez lenses achieve a wide varifocal range through small lateral displacement offering a compact design and a large varifocal range. Besides the parameter of lateral displacement, the varifocal range and the imaging performance of the Alvarez lenses are influenced by other parameters. This paper aims to explore and analyze how different parameters impact the imaging performance of Alvarez lenses. The analysis focuses on the two parameters, i.e., the vector height modulation coefficient(A), the tilt of the freeform surface (D), air gaps, and installation errors. Parameter A controls the height difference between peaks and valleys of the freeform surface and directly affects the varifocal capability of the Alvarez lenses. Through the optical simulation of the Alvarez lens via OpticStudio software, we found that a decrease in the value of parameter A helps to reduce the rate of performance degradation. However, the smaller value of the parameter A necessitates a larger lateral displacement to achieve equivalent changes in focal length. The increase in displacement results in higher power consumption and a slower response time. Thus, selecting an optimal A value and refining D are crucial to enhancing the Alvarez lenses's overall performance. To identify the optimized parameters, we simulated five different sets of the param
With the rapid development of smart phone,the location-based services(LBS)have received great attention in the past *** to the widespread use of WiFi and Bluetooth devices,Received Signal Strength Indication(RSSI)fing...
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With the rapid development of smart phone,the location-based services(LBS)have received great attention in the past *** to the widespread use of WiFi and Bluetooth devices,Received Signal Strength Indication(RSSI)fingerprintbased localization method has obtained much development in both academia and *** this work,we introduce an efficient way to reduce the labor-intensive site survey process,which uses an UWB/IMU-assisted fingerprint construction(UAFC)and localization framework based on the principle of Automatic radio map generation scheme(ARMGS)is proposed to replace the traditional manual *** be specific,UWB devices are employed to estimate the coordinates when the collector is moved in a reference point(RP).An anchor self-localization method is investigated to further reduce manual measurement work in a wide and complex environment,which is also a grueling,time-consuming process that is lead to artificial ***,the measurements of IMU are incorporated into the UWB localization algorithm and improve the label accuracy in *** addition,the weighted k-nearest neighbor(WKNN)algorithm is applied to online localization ***,filed experiments are carried out and the results confirm the effectiveness of the proposed approach.
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