scholarly journals Three-Dimensional Terahertz Coded-Aperture Imaging Based on Back Projection

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2510 ◽  
Author(s):  
Shuo Chen ◽  
Chenggao Luo ◽  
Hongqiang Wang ◽  
Wenpeng Wang ◽  
Long Peng ◽  
...  
Keyword(s):  
Computational Complexity ◽  
Pulse Compression ◽  
Signal To Noise Ratio ◽  
Reference Signal ◽  
Three Dimensional ◽  
Coded Aperture ◽  
Imaging Method ◽  
Back Projection ◽  
Coded Aperture Imaging ◽  
Resolution Imaging

Terahertz coded-aperture imaging (TCAI) can overcome the difficulties of traditional radar in forward-looking and high-resolution imaging. Three-dimensional (3D) TCAI relies mainly on the reference-signal matrix (RSM), the large size and poor accuracy of which reduce the computational efficiency and imaging ability, respectively. According to the previous research on TCAI, traditional TCAI cannot reduce the heavy computational burden while the improved TCAI achieve reconstructing the target parts of different ranges in parallel. However, large-sized RSM still accounts for the computational complexity of traditional TCAI and the improved TCAI. Therefore, this paper proposes a more efficient imaging method named back projection (BP)-TCAI (BP-TCAI). Referring to the basic principle of BP, BP-TCAI can not only divide the scattering information in different ranges but also project the range profiles into different imaging subareas. In this way, the target parts in different subareas can be reconstructed simultaneously to synthesize the whole 3D target and thus decomposes the computational complexity thoroughly. During the pulse compression and projection processes, the signal-to-noise ratio (SNR) of BP-TCAI is also improved. This present the imaging method, model and procedures of traditional TCAI, the improved TCAI and the proposed BP-TCAI. Numerical experimental results prove BP-TCAI to be more effective and efficient than previous imaging methods of TCAI. Besides, BP-TCAI can also be seen as synthetic aperture radar (SAR) imaging with coding technology. Therefore, BP-TCAI opens a future gate combining traditional SAR and coded-aperture imaging.

scholarly journals Phaseless Terahertz Coded-Aperture Imaging for Sparse Target Based on Phase Retrieval Algorithm

Sensors ◽  
2019 ◽  
Vol 19 (21) ◽  
pp. 4617 ◽  
Author(s):  
Peng ◽  
Luo ◽  
Deng ◽  
Wang ◽  
Chen ◽  
...  
Keyword(s):  
Phase Retrieval ◽  
Computational Imaging ◽  
Retrieval Algorithm ◽  
Coded Aperture ◽  
Imaging Method ◽  
Coded Aperture Imaging ◽  
Imaging Model ◽  
Random Frequency ◽  
Resolution Imaging ◽  
Sparse Prior

Phaseless terahertz coded-aperture imaging (PL-TCAI) is a novel radar computational imaging method that utilizes the coded aperture and the incoherent detector array to achieve forward-looking and high-resolution imaging without relying on relative motion. In this paper, we propose a more reasonable and compact architecture for the PL-TCAI system and derive the imaging model of PL-TCAI based on the random frequency-hopping signal. Since most phase retrieval algorithms for PL-TCAI utilize only the intensity of echo signals to accurately reconstruct the target, excessive measurement samples are usually required. In order to reduce the number of measurement samples required for imaging, this paper proposes a sparse Wirtinger flow algorithm with optimal stepsize (SWFOS) by using the sparse prior of the target. The specific procedures of the SWFOS algorithm include the support recovery, initialization by truncated spectral method, iteration via gradient descent scheme, hard threshold operation, and stepsize optimization of iteration. Numerical simulations are performed, and the results show that the SWFOS algorithm not only has good performance for the PR problem, but can also sharply reduce the number of measurement samples required for imaging in the PL-TCAI system.

scholarly journals Three-Dimensional Microwave Holographic Imaging Employing Forward-Scattered Waves Only

2013 ◽  
Vol 2013 ◽  
pp. 1-15 ◽  
Author(s):  
Reza K. Amineh ◽  
Maryam Ravan ◽  
Justin McCombe ◽  
Natalia K. Nikolova
Keyword(s):  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Imaging Method ◽  
Two Dimensional ◽  
Signal To Noise ◽  
High Loss ◽  
Holographic Imaging ◽  
Multiple Receivers ◽  
Satisfactory Performance ◽  
Resolution Limits

We propose a three-dimensional microwave holographic imaging method based on the forward-scattered waves only. In the proposed method, one transmitter and multiple receivers perform together a two-dimensional scan on two planar apertures on opposite sides of the inspected domain. The ability to achieve three-dimensional imaging without back-scattered waves enables the imaging of high-loss objects, for example, tissues, where the back-scattered waves may not be available due to low signal-to-noise ratio or nonreciprocal measurement setup. The simulation and experimental results demonstrate the satisfactory performance of the proposed method in providing three-dimensional images. Resolution limits are derived and confirmed with simulation examples.

Radar coded aperture imaging for three dimensional target

2017 ◽  
Author(s):  
Shuo Chen ◽  
Chenggao Luo ◽  
Bin Deng ◽  
Yuliang Qin ◽  
Hongqiang Wang ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Coded Aperture ◽  
Coded Aperture Imaging

scholarly journals A Novel 3D Imaging Method for Airborne Downward-Looking Sparse Array SAR Based on Special Squint Model

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Xiaozhen Ren ◽  
Yao Qin ◽  
Lihong Qiao
Keyword(s):  
3D Imaging ◽  
Three Dimensional ◽  
Imaging Method ◽  
Computationally Efficient ◽  
Theory Analysis ◽  
Imaging Geometry ◽  
Range Resolution ◽  
Sparse Array ◽  
Resolution Imaging ◽  
Cross Track

Three-dimensional (3D) imaging technology based on antenna array is one of the most important 3D synthetic aperture radar (SAR) high resolution imaging modes. In this paper, a novel 3D imaging method is proposed for airborne down-looking sparse array SAR based on the imaging geometry and the characteristic of echo signal. The key point of the proposed algorithm is the introduction of a special squint model in cross track processing to obtain accurate focusing. In this special squint model, point targets with different cross track positions have different squint angles at the same range resolution cell, which is different from the conventional squint SAR. However, after theory analysis and formulation deduction, the imaging procedure can be processed with the uniform reference function, and the phase compensation factors and algorithm realization procedure are demonstrated in detail. As the method requires only Fourier transform and multiplications and thus avoids interpolations, it is computationally efficient. Simulations with point scatterers are used to validate the method.

High-resolution terahertz coded-aperture imaging for near-field three-dimensional target

2019 ◽  
Vol 58 (12) ◽  
pp. 3293 ◽  
Author(s):  
Cheng-Gao Luo ◽  
Bin Deng ◽  
Hong-Qiang Wang ◽  
Yu-Liang Qin
Keyword(s):  
High Resolution ◽  
Near Field ◽  
Three Dimensional ◽  
Coded Aperture ◽  
Coded Aperture Imaging
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