FMCW ISAR Autofocus Imaging Algorithm for High-Speed Maneuvering Targets Based on Image Contrast-Based Autofocus and Phase Retrieval

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.

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Simultaneous Measurement of In-Plane and Out-of-Plane Deformations Using Dual-Beam Spatial-Carrier Digital Speckle Pattern Interferometry

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.782.316 ◽

2015 ◽

Vol 782 ◽

pp. 316-325 ◽

Cited By ~ 3

Author(s):

Kai Liu ◽

Si Jin Wu ◽

Xin Ya Gao ◽

Lian Xiang Yang

Keyword(s):

High Speed ◽

Phase Retrieval ◽

Speckle Pattern ◽

High Tech ◽

Advanced Technique ◽

Digital Speckle Pattern Interferometry ◽

Dual Beam ◽

Out Of Plane ◽

Digital Speckle ◽

Plane Deformations

Digital speckle pattern interferometry (DSPI) is an advanced technique for both in-plane and out-of-plane deformation measurements of diffuse surfaces in nanoscale. It has been widely used in aerospace engineering and other high-tech industries due to the advantages of non-contact, high-accuracy and full-field measurement. Traditionally, DSPI uses temporal phase shifting method to achieve precise deformation measurement, but it is only suitable for quasi-static deformation. Spatial-carrier method is another effective phase retrieval method used in DSPI and its validity has been verified in some DSPI setups. DSPI with spatial-carrier method enjoys the advantages of simple optical arrangement, easy operation, and above all, high-speed measurement of deformation. This paper introduces a dual-beam spatial-carrier digital speckle pattern interferometry system, with which in-plane and out-of-plane deformations can be measured simultaneously as well as quickly. In the optical setup, two lasers are employed to illuminate the measured object with different illumination angles, and two single-mode fibers server as carriers to transmit the reference beams. In-plane and out-of-plane deformations can be obtained by combining the phase maps of both channels. Theoretical discussion and experimental analysis are both presented.

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Hybrid phase retrieval algorithm based on modified very fast simulated annealing

International Journal of Microwave and Wireless Technologies ◽

10.1017/s1759078718000971 ◽

2018 ◽

Vol 10 (9) ◽

pp. 1072-1080 ◽

Cited By ~ 1

Author(s):

Yueshu Xu ◽

Qian Ye ◽

Guoxiang Meng

Keyword(s):

Simulated Annealing ◽

High Speed ◽

Phase Retrieval ◽

Global Minimum ◽

High Efficiency ◽

Surface Deformation ◽

Digital Simulation ◽

Retrieval Algorithm ◽

Very Fast Simulated Annealing ◽

Short Time

AbstractThe Misell algorithm is one of the most widely used phase retrieval holography methods for large reflector antennas to measure surface deformation. However, it usually locks in a local minimum because it heads downhill from an initial estimation without any consideration whether it heads for a global minimum or not. The core problem of the Misell algorithm is to find an initial estimation near the global minimum to avoid local stagnation. To cope with the problem, we construct a hybrid Misell algorithm, named modified very fast simulated annealing (MVFSA)-Misell algorithm, to search for the global minimum with a high efficiency. The algorithm is based on the combination of the MVFSA algorithm and Misell algorithm. Firstly, the MVFSA is utilized to obtain a rough position near the global minimum in limited steps. Then, the Misell algorithm starts from the rough position to converge to the global minimum with high speed and accuracy. The convergence characteristic of the proposed algorithm was discussed in detail through digital simulation. Simulation results show that the algorithm can reach global minimum in a very short time. Unlike the traditional Misell algorithm, the hybrid algorithm is not influenced by initial phase estimation.

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High speed implementation of a three-dimensional shape profiler with submillimeter precision using a digital light processing device and a new efficient algorithm for absolute phase retrieval

Optical Engineering ◽

10.1117/1.oe.54.3.034102 ◽

2015 ◽

Vol 54 (3) ◽

pp. 034102 ◽

Cited By ~ 3

Author(s):

Audrey Leong-Hoï ◽

Paul C. Montgomery ◽

Bruno Serio ◽

Patrice Twardowski

Keyword(s):

Efficient Algorithm ◽

High Speed ◽

Phase Retrieval ◽

Three Dimensional ◽

Digital Light Processing ◽

Absolute Phase ◽

Dimensional Shape ◽

Three Dimensional Shape ◽

Processing Device

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Echo Model Analyses and Imaging Algorithm for High-Resolution SAR on High-Speed Platform

IEEE Transactions on Geoscience and Remote Sensing ◽

10.1109/tgrs.2011.2162243 ◽

2012 ◽

Vol 50 (3) ◽

pp. 933-950 ◽

Cited By ~ 33

Author(s):

Yan Liu ◽

Mengdao Xing ◽

Guangcai Sun ◽

Xiaolei Lv ◽

Zheng Bao ◽

...

Keyword(s):

High Resolution ◽

High Speed ◽

Imaging Algorithm

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High-speed holographic imaging using compressed sensing and phase retrieval

10.1117/12.2262737 ◽

2017 ◽

Author(s):

Zihao Wang ◽

Donghun Ryu ◽

Kuan He ◽

Roarke Horstmeyer ◽

Aggelos Katsaggelos ◽

...

Keyword(s):

Compressed Sensing ◽

High Speed ◽

Phase Retrieval ◽

Holographic Imaging

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Fast reconstruction tools for ptychography at Sirius, the fourth-generation Brazilian synchrotron

Journal of Applied Crystallography ◽

10.1107/s1600576720013886 ◽

2020 ◽

Vol 53 (6) ◽

pp. 1550-1558

Author(s):

Giovanni L. Baraldi ◽

Carlos S. B. Dias ◽

Francisco M. C. Silva ◽

Hélio C. N. Tolentino ◽

Eduardo X. Miqueles

Keyword(s):

High Speed ◽

High Performance ◽

Phase Retrieval ◽

Scattering Data ◽

Fourth Generation ◽

Acquisition Time ◽

Optimization Strategy ◽

X Ray ◽

Mixed Precision ◽

Synchrotron Light

Described here are image reconstruction optimizations for ptychographic coherent X-ray scattering data and X-ray fluorescence, which have been developed for the new fourth-generation synchrotron light source, Sirius, at the Brazilian Synchrotron Light Laboratory. The optimization strategy has been applied to the standard experimental strategy for ptychographic and fluorescence experiments on the Carnaúba beamline which involves the use of high-speed continuous scans (fly scans) for a fast acquisition time over large areas through the use of a newly proposed trajectory named the alternating linear trajectory. The scientific computing developments presented here target an efficient use of graphical processing units (GPUs) to the point where large fly-scan acquisitions can be processed in real time on a local high-performance computer. Some optimizations involving a custom fast Fourier transform implementation and use of mixed precision can be applied to other algorithms and phase-retrieval techniques, and therefore this work provides a general optimization scheme. Finally, the optimization strategy presented here has improved performance by a factor of ∼2.5 times faster when compared with non-optimized GPU implementations.

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ISAR Autofocus Imaging Algorithm for Maneuvering Targets Based on Phase Retrieval and Keystone Transform

International Journal of Antennas and Propagation ◽

10.1155/2019/8781979 ◽

2019 ◽

Vol 2019 ◽

pp. 1-11 ◽

Cited By ~ 1

Author(s):

Hongyin Shi ◽

Ting Yang ◽

Yue Liu ◽

Jingjing Si

Keyword(s):

Rotational Motion ◽

Phase Retrieval ◽

Translational Motion ◽

Retrieval Algorithm ◽

Imaging Method ◽

Keystone Transform ◽

Maneuvering Targets ◽

Coherent Integration ◽

Motion Parameters ◽

Phase Retrieval Algorithm

In the current scenario of high-range resolution radar and noncooperative target, the rotational motion parameters of the target are unknown and migration through resolution cells (MTRC) is apparent in the obtained inverse synthetic aperture radar (ISAR)images, in both slant-range and cross-range directions. In the case of the high-speed maneuvering target with a small value of rotation, the phase retrieval algorithm can be applied to compensate for the translational motion to form an autofocusing image. However, when the target has a relatively large rotation angle during the coherent integration time, phase retrieval method cannot get an acceptable image for viewing and analysis as the location of the scatterer will not be true due to the Doppler shift imposed by the target’s rotational motion. In this paper, a novel ISAR imaging method for maneuvering targets based on phase retrieval and keystone transform is proposed, which can effectively solve the above problems. First, the keystone transform is used to solve the MTRC effects caused by the rotation component. Next, phase errors caused by the remaining translational motion will be removed by employing phase retrieval algorithm, allowing the scatterers are always kept in their range cells. Finally, the Doppler frequency shifts of scatterers will be time invariant in the phase of the received signal. Furthermore, this approach does not need to estimate the motion parameters of the target, which simplifies the processing steps. The simulated results demonstrate the validity of this method.

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