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spatial-and-frequency-domain
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Improved-resolution millimeter-wave imaging through structured illumination
, Article Applied Optics ; Volume 56, Issue 15 , 2017 , Pages 4454-4465 ; 1559128X (ISSN) ; Kavehvash, Z ; Shabany, M ; Sharif University of Technology
Abstract
A resolution-improved active millimeter-wave (MMW) imaging structure, based on the theory of structured illumination, is proposed in this paper. The structured illumination is a well-defined concept for surpassing the diffraction limit in optical microscopy, where imposing grating patterns on the targeted object could help in moving the object frequency spectrum along the desired direction in the spatial frequency domain. This frequency shift helps in passing different parts of the object's frequency spectrum through the diffraction filter. The combination of resultant images provides a framework to pass a wider frequency band of the object, thereby achieving super-resolution. This idea has...
Beamforming, null-steering, and simultaneous spatial and frequency domain filtering in integrated phased array systems
, Article AEU - International Journal of Electronics and Communications ; Volume 110 , 2019 ; 14348411 (ISSN) ; Atarodi, S. M ; Sharif University of Technology
Elsevier GmbH
2019
Abstract
In the case that phased array systems are not capable of attenuating interferences, Radio Frequency (RF) front-ends and Analog Digital Converters (ADCs) with a large dynamic range are required to avoid saturation of the receiver. This leads to a higher power consumption. In this paper, employing N-path circuits in Mixer-First receivers, a novel method is introduced in which spatial and frequency blockers are eliminated right before entering the system on the antennas input. In fact using this technique, adjustable spatial notch filter and band-pass frequency filter are implemented to suppress spatial and frequency interferences. The proposed method enhances the robustness and effectiveness...
Super-resolution photoacoustic microscopy using structured-illumination
, Article IEEE Transactions on Medical Imaging ; Volume 40, Issue 9 , 2021 , Pages 2197-2207 ; 02780062 (ISSN) ; Mostafavi, M ; Chen, J ; Kavehvash, Z ; Zhu, J ; Wang, L ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
A novel super-resolution volumetric photoacoustic microscopy, based on the theory of structured-illumination, is proposed in this paper. The structured-illumination will be introduced in order to surpass the diffraction limit in a photoacoustic microscopy (PAM) structure. Through optical excitation of the targeted object with a sinusoidal spatial fringe pattern, the object's frequency spectrum is forced to shift in the spatial frequency domain. The shifting in the desired direction leads to the passage of the high-frequency contents of the object through the passband of the acoustic diffraction frequency response. Finally, combining the low-frequency image with the high-frequency parts in...