Terahertz digital off-axis holography for non-destructive testing

Heimbeck, Martin S.; Kim, Myung K.; Gregory, Don A.; Everitt, Henry O.

doi:10.1109/irmmw-thz.2011.6105090

Cited by 10 publications

(3 citation statements)

References 6 publications

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“…Millimeter-wave (MMW) and terahertz (THz) wave imaging systems with wide bandwidth have attracted more and more attention in various applications, including safety/security, non-destructive testing (NDT) [1][2][3][4][5], due to their millimeter/submillimeterscale resolution and better penetration for nonmetal materials [3].…”

Section: Introductionmentioning

confidence: 99%

A Millimeter-Wave 3D Imaging Algorithm for MIMO Synthetic Aperture Radar

Lin

et al. 2023

Sensors

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Multiple-input-multiple-output synthetic aperture radar (MIMO-SAR) is being studied and applied in more and more scenarios. However, there is still a certain distance away from real-time imaging using advanced algorithms. The traditional backpropagation algorithm (BPA) multi-accumulation integration is unsuitable for dealing with large-size scanning data, and the wavenumber domain algorithm requires the array to satisfy Nyquist sampling law in azimuth to avoid aliasing in imaging reconstruction. Based on these issues, a novel 3D imaging method is proposed for MIMO-SAR. An appropriate transformation and inverse Fourier transform (FT) is carried out for the frequency domain; thus, accumulation in the wavenumber domain is not required, which is easy to implement. The computational complexity of the algorithm is much lower than BPA and has better generalizability than the wavenumber domain algorithm. Coherence factor (CF) is also introduced to achieve sidelobe suppression. Proof-of-principle experiments were also carried out in the 92.5 GHz band based on the MIMO-SAR prototype system. Both simulation and experimental results of different distributed targets show good performance of imaging and do not lose the quality of image reconstruction.

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Section: Introductionmentioning

confidence: 99%

A Millimeter-Wave 3D Imaging Algorithm for MIMO Synthetic Aperture Radar

Lin

et al. 2023

Sensors

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“…Compared to the microwave band, it can achieve a higher imaging resolution [1,2]. Due to the above advantages, the THz imaging systems have attracted extensive attention in the field of security inspection, non-destructive testing (NDT) and other applications [3,4].…”

Section: Introductionmentioning

confidence: 99%

A THz Passive Image Generation Method Based on Generative Adversarial Networks

Yang

Liu

et al. 2022

Applied Sciences

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A terahertz (THz) passive imager with automatic target detection is an effective solution in the field of security inspection. The high-quality training datasets always play a key role in the high-precision target detection applications. However, due to the difficulty of passive image data acquisition and the lack of public dataset resources, the high-quality training datasets are often insufficient. The generative adversarial network (GAN) is an effective method for data augmentation. To enrich the dataset with the generated images, it is necessary to ensure that the generated images have high quality, good diversity, and correct category information. In this paper, a GAN-based generation model is proposed to generate terahertz passive images. By applying different residual connection structures in the generator and discriminator, the models have strong feature extracting ability. Additionally, the Wasserstein loss function with gradient penalty is used to maintain training stability. The self-developed 0.2 THz band passive imager is used to carry out imaging experiments, and the imaging results are collected as a dataset to verify the proposed method. Finally, a quality evaluation method suitable for THz passive image generation task is proposed, and classification tests are performed on the generated images. The results show that the proposed method can provide high-quality images as supplementary.

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“…Generally, THz waves are referred to the spectrum from 0.1 to 10 THz, which lie in the gap between the microwave and infrared. In recent years, many THz imaging systems have been designed and developed for various applications, particularly for nondestructive testing (NDT) and security inspection [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Phase Shift Migration With SIMO Superposition for MIMO-Sidelooking Imaging at Terahertz Band

Yang

Gao

et al. 2020

IEEE Access

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In this paper, the enhanced phase shift migration (PSM) algorithm for multi-input-multioutput (MIMO) side-looking (SL) scheme was proposed for the 2-dimension (2D) fast image reconstruction in the terahertz (THz) band. By decomposing the MIMO imaging problem into a superposition of several single-input-multiple-output (SIMO) sub-arrays, the proposed algorithm can be applied to systems with randomly distributed transmitting array. By deriving and applying the modified phase shift factor and necessary phase compensation, zero-padding in the transmitting array and data reorganization in the spatialfrequency domain of the conventional wavenumber domain MIMO algorithm can be totally avoided, which will hopefully further reduce the amount of calculation. A comprehensive MIMO-SL-EPSM algorithm was established in the wavenumber domain. Proof-of-principle experiments in the 0.1-THz band were performed based on a MIMO-SL prototype system. The reconstructed images for different targets with high efficiency and quality demonstrate the theoretical results and the effectiveness of the proposed algorithm. INDEX TERMS multiple-input-multiple-output (MIMO), phase shift migration (PSM), terahertz (THz), image reconstruction algorithm.

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Terahertz digital off-axis holography for non-destructive testing

Cited by 10 publications

References 6 publications

A Millimeter-Wave 3D Imaging Algorithm for MIMO Synthetic Aperture Radar

A Millimeter-Wave 3D Imaging Algorithm for MIMO Synthetic Aperture Radar

A THz Passive Image Generation Method Based on Generative Adversarial Networks

Phase Shift Migration With SIMO Superposition for MIMO-Sidelooking Imaging at Terahertz Band

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