scholarly journals Phaseless Terahertz Coded-Aperture Imaging Based on Deep Generative Neural Network

2021 ◽  
Vol 13 (4) ◽  
pp. 671
Author(s):  
Fengjiao Gan ◽  
Ziyang Yuan ◽  
Chenggao Luo ◽  
Hongqiang Wang
Keyword(s):  
Phase Retrieval ◽  
Generative Models ◽  
System Structure ◽  
Retrieval Algorithm ◽  
Coded Aperture ◽  
Intensity Measurements ◽  
Coded Aperture Imaging ◽  
Extended Target ◽  
The Matrix ◽  
High Resolution Reconstruction

As a promising terahertz radar imaging technology, phaseless terahertz coded-aperture imaging (PL-TCAI) has many advantages such as simple system structure, forward-looking imaging and staring imaging and so forth. However, it is very difficult to recover a target only from its intensity measurements. Although some methods have been proposed to deal with this problem, they require a large number of intensity measurements for both sparse and extended target reconstruction. In this work, we propose a method for PL-TCAI by modeling target scattering coefficient as being in the range of a generative model. Theoretically, we analyze and model the system structure, derive the matrix imaging equation, and then study the deep phase retrieval algorithm. Numerical tests based on different generative models show that the targets with the different spareness can achieve high resolution reconstruction when the number of intensity measurements are smaller than the number of target grids. Also, we find that the proposed method has good anti-noise and stability.

scholarly journals Phaseless Terahertz Coded-Aperture Imaging Based on Incoherent Detection

Sensors ◽  
2019 ◽  
Vol 19 (2) ◽  
pp. 226 ◽  
Author(s):  
Long Peng ◽  
Chenggao Luo ◽  
Bin Deng ◽  
Hongqiang Wang ◽  
Yuliang Qin ◽  
...  
Keyword(s):  
High Resolution ◽  
High Speed ◽  
Phase Retrieval ◽  
Time Frame ◽  
Frame Rate ◽  
Future Research ◽  
Coded Aperture ◽  
Main Work ◽  
Coded Aperture Imaging ◽  
The Matrix

In this paper, we propose a phaseless terahertz coded-aperture imaging (PTCAI) method by using a single incoherent detector or an incoherent detection array. We at first analyze and model the system architecture, derive the matrix imaging equation, and then study the phase retrieval techniques to reconstruct the original target with high resolution. Numerical experiments are performed and the results show that the proposed method can significantly reduce the system complexity in the receiving process while maintaining high resolution imaging capability. Furthermore, the approach of using incoherent detection array instead of single detector is capable of decreasing the encoding and sampling times, and therefore helps to improve the imaging frame rate. In our future research, the method proposed in this paper will be experimentally tested and validated, and high-speed PTCAI at nearly real-time frame rates will be the main work.

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 Two-Step Phase Retrieval Algorithm Using Single-Intensity Measurement

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Cheng Zhang ◽  
Meiqin Wang ◽  
Qianwen Chen ◽  
Dong Wang ◽  
Sui Wei
Keyword(s):  
Phase Retrieval ◽  
Fourier Spectrum ◽  
Retrieval Algorithm ◽  
Improved Method ◽  
Retrieval Method ◽  
Intensity Measurements ◽  
Successful Recovery ◽  
Reconstruction Quality ◽  
Low Probability ◽  
Phase Retrieval Algorithm

Aiming at the problem that the single-intensity phase retrieval method has poor reconstruction quality and low probability of successful recovery, an improved method is proposed in this paper. Our method divides the phase retrieval into two steps: firstly, the GS algorithm is used to recover the amplitude in the spatial domain from the single-spread Fourier spectrum, and then the classical GS algorithm using two intensity measurements (one is recorded and the other is estimated from the first step) measurements is used to recover the phase. Finally, the effectiveness of the proposed method is verified by numerical experiments.

Application of Phase Retrieval Algorithms in Terahertz Coded-Aperture Imaging

2019 ◽  
Author(s):  
Long Peng ◽  
Chenggao Luo ◽  
Hongqiang Wang ◽  
Yongqiang Cheng ◽  
Qi Yang ◽  
...  
Keyword(s):  
Phase Retrieval ◽  
Coded Aperture ◽  
Coded Aperture Imaging ◽  
Retrieval Algorithms

scholarly journals Complex Wavefront Shaping through a Multi-Core Fiber

2021 ◽  
Vol 11 (9) ◽  
pp. 3949
Author(s):  
Jiawei Sun ◽  
Nektarios Koukourakis ◽  
Jürgen W. Czarske
Keyword(s):  
Phase Retrieval ◽  
Light Field ◽  
Discrete Distribution ◽  
Cell Manipulation ◽  
Retrieval Algorithm ◽  
Optical Cell ◽  
Loop Control ◽  
Wavefront Shaping ◽  
Core Fiber ◽  
Phase Retrieval Algorithm

Wavefront shaping through a multi-core fiber (MCF) is turning into an attractive method for endoscopic imaging and optical cell-manipulation on a chip. However, the discrete distribution and the low number of cores induce pixelated phase modulation, becoming an obstacle for delivering complex light field distributions through MCFs. We demonstrate a novel phase retrieval algorithm named Core–Gerchberg–Saxton (Core-GS) employing the captured core distribution map to retrieve tailored modulation hologram for the targeted intensity distribution at the distal far-field. Complex light fields are reconstructed through MCFs with high fidelity up to 96.2%. Closed-loop control with experimental feedback denotes the capability of the Core-GS algorithm for precise intensity manipulation of the reconstructed light field. Core-GS provides a robust way for wavefront shaping through MCFs; it facilitates the MCF becoming a vital waveguide in endoscopic and lab-on-a-chip applications.

Laboratory coded-aperture imaging experiments: radial hole coded masks and depth-sensitive CZT detectors

2004 ◽  
Author(s):  
Jae Sub Hong ◽  
Santosh V. Vadawale ◽  
Minhua Zhang ◽  
Eric C. Bellm ◽  
Andrew Yousef ◽  
...  
Keyword(s):  
Coded Aperture ◽  
Coded Aperture Imaging ◽  
Czt Detectors

Hidden projection tomography via phase retrieval algorithm

2021 ◽  
Author(s):  
Daniele Ancora ◽  
Diego Di Battista ◽  
Asier Marcos Vidal ◽  
Stella Avtzi ◽  
Giannis Zacharakis ◽  
...  
Keyword(s):  
Phase Retrieval ◽  
Retrieval Algorithm ◽  
Phase Retrieval Algorithm
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