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

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
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.

scholarly journals Non-Stationary Platform Inverse Synthetic Aperture Radar Maneuvering Target Imaging Based on Phase Retrieval

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3333 ◽  
Author(s):  
Hongyin Shi ◽  
Saixue Xia ◽  
Qi Qin ◽  
Ting Yang ◽  
Zhijun Qiao
Keyword(s):  
Synthetic Aperture Radar ◽  
Phase Retrieval ◽  
Experimental Simulation ◽  
Synthetic Aperture ◽  
Retrieval Algorithm ◽  
Imaging Method ◽  
Inverse Synthetic Aperture Radar ◽  
Maneuvering Target ◽  
Motion Parameters ◽  
Aperture Radar

As a powerful signal processing tool for imaging moving targets, placing radar on a non-stationary platform (such as an aerostat) is a future direction of Inverse Synthetic Aperture Radar (ISAR) systems. However, more phase errors are introduced into the received signal due to the instability of the radar platform, making it difficult for popular algorithms to accurately perform motion compensation, which leads to severe effects in the resultant ISAR images. Moreover, maneuvering targets may have complex motion whose motion parameters are unknown to radar systems. To overcome the issue of non-stationary platform ISAR autofocus imaging, a high-resolution imaging method based on the phase retrieval principle is proposed in this paper. Firstly, based on the spatial geometric and echo models of the ISAR maneuvering target, we can deduce that the radial motion of the radar platform or the vibration does not affect the modulus of the ISAR echo signal, which provides a theoretical basis for the phase recovery theory for the ISAR imaging. Then, we propose an oversampling smoothness (OSS) phase retrieval algorithm with prior information, namely, the phase of the blurred image obtained by the classical imaging algorithm replaces the initial random phase in the original OSS algorithm. In addition, the size of the support domain of the OSS algorithm is set with respect to the blurred target image. Experimental simulation shows that compared with classical imaging methods, the proposed method can obtain the resultant motion-compensated ISAR image without estimating the radar platform and maneuvering target motion parameters, wherein the fictitious target is perfectly focused.

SAR imaging method for sea scene target based on improved phase retrieval algorithm

2016 ◽  
Vol 27 (6) ◽  
pp. 1176-1182 ◽  
Author(s):  
Hongyin Shi ◽  
◽  
Qiuxiao Zhou ◽  
Xiaoyan Yang ◽  
Qiusheng Lian ◽  
...  
Keyword(s):  
Phase Retrieval ◽  
Retrieval Algorithm ◽  
Imaging Method ◽  
Sar Imaging ◽  
Phase Retrieval Algorithm

scholarly journals ISAR Autofocus Imaging Algorithm for Maneuvering Targets Based on Phase Retrieval and Gabor Wavelet Transform

2018 ◽  
Vol 10 (11) ◽  
pp. 1810 ◽  
Author(s):  
Hongyin Shi ◽  
Ting Yang ◽  
Zhijun Qiao
Keyword(s):  
Wavelet Transform ◽  
Motion Compensation ◽  
Rotational Motion ◽  
Phase Retrieval ◽  
Translational Motion ◽  
Gabor Wavelet ◽  
Retrieval Algorithm ◽  
Gabor Wavelet Transform ◽  
Time Frequency ◽  
Maneuvering Target

The imaging issue of a rotating maneuvering target with a large angle and a high translational speed has been a challenging problem in the area of inverse synthetic aperture radar (ISAR) autofocus imaging, in particular when the target has both radial and angular accelerations. In this paper, on the basis of the phase retrieval algorithm and the Gabor wavelet transform (GWT), we propose a new method for phase error correction. The approach first performs the range compression on ISAR raw data to obtain range profiles, and then carries out the GWT transform as the time-frequency analysis tool for the rotational motion compensation (RMC) requirement. The time-varying terms, caused by rotational motion in the Doppler frequency shift, are able to be eliminated at the selected time frame. Furthermore, the processed backscattered signal is transformed to the one in the frequency domain while applying the phase retrieval to run the translational motion compensation (TMC). Phase retrieval plays an important role in range tracking, because the ISAR echo module is not affected by both radial velocity and the acceleration of the target. Finally, after the removal of both the rotational and translational motion errors, the time-invariant Doppler shift is generated, and radar returned signals from the same scatterer are always kept in the same range cell. Therefore, the unwanted motion effects can be removed by applying this approach to have an autofocused ISAR image of the maneuvering target. Furthermore, the method does not need to estimate any motion parameters of the maneuvering target, which has proven to be very effective for an ideal range–Doppler processing. Experimental and simulation results verify the feasibility of this approach.

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.

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

Phase-shifting digital holography with an unknown reference beam

2021 ◽  
Author(s):  
Roghayeh Yazdani ◽  
Hamidreza Fallah
Keyword(s):  
Digital Holography ◽  
Phase Retrieval ◽  
Reference Beam ◽  
Phase Shifting ◽  
Retrieval Algorithm ◽  
Reference Field ◽  
Digital Holograms ◽  
Noisy Conditions ◽  
Phase Retrieval Algorithm

In digital holography, errors of the reference field degrade the quality of the reconstructed object field. In this paper, we propose an effective method in phase-shifting digital holography in which the reference field does not need to be known and perfect. The unknown complex amplitudes of both reference and object fields are derived simultaneously. The method employs only five digital holograms and a single execution of a phase retrieval algorithm. So, the required measurements and algorithm executions in this method are fewer than those in other methods; it suggests a simpler and faster method. The effectiveness of the suggested method is indicated by simulation, under noise-free and noisy conditions. Moreover, the capability of the method to extract full information about the phase singularities in both fields is demonstrated.

scholarly journals Measurement of Small-Slope Free-Form Optical Surfaces with the Modified Phase Retrieval

Micromachines ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 82
Author(s):  
Xinxue Ma ◽  
Jianli Wang ◽  
Bin Wang ◽  
Xinyue Liu
Keyword(s):  
Wave Front ◽  
Phase Retrieval ◽  
Computation Time ◽  
Experimental Arrangement ◽  
Free Form ◽  
Retrieval Algorithm ◽  
Retrieval Method ◽  
Optical Surfaces ◽  
Image Capturing ◽  
Phase Retrieval Algorithm

In this paper, we demonstrate the use of the modified phase retrieval as a method for application in the measurement of small-slope free-form optical surfaces. This technique is a solution for the measurement of small-slope free-form optical surfaces, based on the modified phase retrieval algorithm, whose essence is that only two defocused images are needed to estimate the wave front with an accuracy similar to that of the traditional phase retrieval but with less image capturing and computation time. An experimental arrangement used to measure the small-slope free-form optical surfaces using the modified phase retrieval is described. The results of these experiments demonstrate that the modified phase retrieval method can achieve measurements comparable to those of the standard interferometer.

Sign in / Sign up

Export Citation Format

Share Document