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Syed Akbar Ali MS, Rajagopal P. Far-field ultrasonic imaging using hyperlenses. Sci Rep 2022; 12:18222. [PMID: 36309580 PMCID: PMC9617850 DOI: 10.1038/s41598-022-23046-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 10/25/2022] [Indexed: 12/31/2022] Open
Abstract
Hyperlenses for ultrasonic imaging in nondestructive evaluation and non-invasive diagnostics have not been widely discussed, likely due to the lack of understanding on their performance, as well as challenges with reception of the elastic wavefield past fine features. This paper discusses the development and application of a cylindrical hyperlens that can magnify subwavelength features and achieve super-resolution in the far-field. A radially symmetric structure composed of alternating metal and water layers is used to demonstrate the hyperlens. Numerical simulations are used to study the performance of cylindrical hyperlenses with regard to their geometrical parameters in imaging defects separated by a subwavelength distance, gaining insight into their construction for the ultrasonic domain. An elegant extension of the concept of cylindrical hyperlens to flat face hyperlens is also discussed, paving the way for a wider practical implementation of the technique. The paper also presents a novel waveguide-based reception technique that uses a conventional ultrasonic transducer as receiver to capture waves exiting from each fin of the hyperlens discretely. A metallic hyperlens is then custom-fabricated, and used to demonstrate for the first time, a super-resolved image with 5X magnification in the ultrasonic domain. The proposed hyperlens and the reception technique are among the first demonstrations in the ultrasonic domain, and well-suited for practical inspections. The results have important implications for higher resolution ultrasonic imaging in industrial and biomedical applications.
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Affiliation(s)
- Mohamed Subair Syed Akbar Ali
- grid.417969.40000 0001 2315 1926Centre for Nondestructive Evaluation, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, 600036 Tamil Nadu India
| | - Prabhu Rajagopal
- grid.417969.40000 0001 2315 1926Centre for Nondestructive Evaluation, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, 600036 Tamil Nadu India
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2
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Cai Y, Song Y, Ni P, Liu X, Li X. Subwavelength ultrasonic imaging using a deep convolutional neural network trained on structural noise. ULTRASONICS 2021; 117:106552. [PMID: 34411873 DOI: 10.1016/j.ultras.2021.106552] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 08/06/2021] [Accepted: 08/07/2021] [Indexed: 06/13/2023]
Abstract
Subwavelength ultrasonic imaging (SUI) can detect subwavelength flaws beyond the diffraction limit, however, SUI sometimes fails to clearly reveal flaws in C-scans when the signal-to-noise ratio (SNR) is low. In this work, a convolutional neural network (CNN) that takes structural noise into account is developed for SUI to distinguish flaw echoes from structural noise. The network contains a regression CNN for learning features from the structural noise and a learnable soft thresholding layer for classification. Experiments show that the proposed method performs well for imaging subwavelength flaws at different depths and of different sizes. It achieved an F1 score of 97.69 ± 1.56% in detecting flaws as compared to the enhanced ultrasonic flaw detection method with time-dependent threshold. As an example of general application of the method, we also performed SUI on natural flaws in a spheroidal graphite cast iron specimen. The results show that the method can achieve SUI without a theoretical backscattering model and is not limited by noise distribution, multiple scattering, or complex microstructures. Furthermore, the network does not need to prepare flaw echoes for training.
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Affiliation(s)
- Yongxing Cai
- School of Traffic and Transportation Engineering, Central South University, Changsha, Hunan 410075, China
| | - Yongfeng Song
- School of Traffic and Transportation Engineering, Central South University, Changsha, Hunan 410075, China.
| | - Peijun Ni
- Inner Mongolia Metallic Materials Research Institute, Ningbo 315103, China
| | - Xiling Liu
- School of Traffic and Transportation Engineering, Central South University, Changsha, Hunan 410075, China
| | - Xiongbing Li
- School of Traffic and Transportation Engineering, Central South University, Changsha, Hunan 410075, China
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Boccaccio M, Rachiglia P, Malfense Fierro GP, Pio Pucillo G, Meo M. Deep-Subwavelength-Optimized Holey-Structured Metamaterial Lens for Nonlinear Air-Coupled Ultrasonic Imaging. SENSORS (BASEL, SWITZERLAND) 2021; 21:1170. [PMID: 33562312 PMCID: PMC7915576 DOI: 10.3390/s21041170] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 01/30/2021] [Accepted: 02/01/2021] [Indexed: 11/16/2022]
Abstract
Ultrasound non-destructive testing (NDT) is a common technique used for defect detection in different materials, from aluminium to carbon-fiber-reinforced polymers (CFRPs). In most cases, a liquid coupling medium/immersion of the inspected component is required to maximize impedance matching, limiting the size of the structure and materials. Air-coupled inspection methods have recently been developed for noncontact inspections to reduce contact issues in standard ultrasonic inspections. However, transmission of ultrasound in air is very inefficient because of the enormous impedance mismatch between solids and air, thus requiring a signal amplification system of high-sensitivity transducers. Hence, the captured signal amplitude may not be high enough to reveal any wave distortion due to defects or damage. This work presents a design of a holey-structured metamaterial lens with a feature size of λ/14 aiming at improvement of acousto-ultrasonic imaging using air-coupled transducers. The required effect is obtained by matching geometrical parameters of the proposed holey-structured metamaterials and the Fabry-Perot resonance modes of the structure. Transmission tests have been conducted on different fabricated metamaterial-based structures, to assess the frequency component filtering of the proposed method in both acoustic (f = 5 kHz, 20 kHz) and ultrasonic range (f = 30 kHz, 40 kHz). Results showed an improved sensitivity of damage imaging, with an increase in amplitude of the design frequencies of the lens by 11 dB. Air-coupled inspections were conducted on a stress-corrosion cracked aluminum plate and impacted CFRP plate using the holey-structured lens. Results showed an improvement in the damage-imaging resolution due to a wave-amplitude increase across the defective features, thus demonstrating its potential as an efficient and sensitive inspection tool for damage-detection improvement in geometrically complex components of different materials.
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Affiliation(s)
- Marco Boccaccio
- Department of Mechanical Engineering, University of Bath, Claverton Down, Bath BA2 7AY, UK; (M.B.); (P.R.); (G.P.M.F.)
| | - Pasquale Rachiglia
- Department of Mechanical Engineering, University of Bath, Claverton Down, Bath BA2 7AY, UK; (M.B.); (P.R.); (G.P.M.F.)
| | - Gian Piero Malfense Fierro
- Department of Mechanical Engineering, University of Bath, Claverton Down, Bath BA2 7AY, UK; (M.B.); (P.R.); (G.P.M.F.)
| | - Giovanni Pio Pucillo
- Department of Industrial Engineering, University of Naples Federico II, 80125 Naples, Italy;
| | - Michele Meo
- Department of Mechanical Engineering, University of Bath, Claverton Down, Bath BA2 7AY, UK; (M.B.); (P.R.); (G.P.M.F.)
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Lambin P, Liubimau A, Bychanok D, Vitale L, Kuzhir P. Thermal and Electromagnetic Properties of Polymer Holey Structures Produced by Additive Manufacturing. Polymers (Basel) 2020; 12:E2892. [PMID: 33276646 PMCID: PMC7761545 DOI: 10.3390/polym12122892] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 11/27/2020] [Indexed: 11/25/2022] Open
Abstract
Multifunctional 3D-printed holey structures made of composite polymers loaded with nanocarbon were designed to serve simultaneously as GHz-radiation absorbing layers and heat conductors. The geometry of the structures was devised to allow heat to be easily transferred through, with special attention paid to thermal conductivity. Numerical calculations and a simple homogenization theory were conducted in parallel to address this property. Different structures have been considered and compared. The electromagnetic shielding effectiveness of the produced holey structures was measured in the microwave range.
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Affiliation(s)
- Philippe Lambin
- Department of Physics, University of Namur, B-5000 Namur, Belgium
- Higher Education Pedagogical Institute, Bukavu, Congo
| | - Aliaksandr Liubimau
- Institute for Nuclear Problems, Belarusian State University, 220030 Minsk, Belarus; (A.L.); (D.B.); (P.K.)
| | - Dzmitry Bychanok
- Institute for Nuclear Problems, Belarusian State University, 220030 Minsk, Belarus; (A.L.); (D.B.); (P.K.)
- Radioelectronics Department, Faculty of Radiophysics, Tomsk State University, 634050 Tomsk, Russia
| | - Luca Vitale
- Narrando srl and Department of Industrial Engineering, University of Salerno, I-84084 Fisciano, Italy;
| | - Polina Kuzhir
- Institute for Nuclear Problems, Belarusian State University, 220030 Minsk, Belarus; (A.L.); (D.B.); (P.K.)
- Institute of Photonics, University of Eastern Finland, FI-80100 Joensuu, Finland
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Anzan-Uz-Zaman M, Song K, Lee DG, Hur S. A novel approach to Fabry-Pérot-resonance-based lens and demonstrating deep-subwavelength imaging. Sci Rep 2020; 10:10769. [PMID: 32612240 PMCID: PMC7330042 DOI: 10.1038/s41598-020-67409-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Accepted: 06/08/2020] [Indexed: 11/09/2022] Open
Abstract
During our research, we explored a novel way to represent subwavelength imaging and derived a transmission equation to explicate the FP (Fabry–Pérot) resonance phenomena. Subsequently, using analysis and observation, we performed deep-subwavelength imaging. Both numerically and experimentally, imaging with super-resolution was achieved at deep subwavelength scale of λ/56.53 with a lens thickness 212 mm. Our results also showed that by increasing lens thickness, higher resolution can be achieved. Moreover, via a single source study, we showed the full width at half maximum range and predicted the size of smallest detectable object. We also observed that with a greater lens thickness, finer features could be detected. These findings may open a new route in near-field imaging for practical applications such as biometric sensors, ultrasonic medical equipment, and non-destructive testing.
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Affiliation(s)
- Md Anzan-Uz-Zaman
- Department of Nature-Inspired Nano Convergence Systems, Korea Institute of Machinery and Materials, 156 Gajeongbuk-Ro, Daejeon, 34103, Republic of Korea.,Nano-Mechatronics, University of Science and Technology, 217 Gajeong-ro, Daejeon, 34103, Republic of Korea
| | - Kyungjun Song
- Department of Mechanical Engineering, Pusan National University, 63-2 Geumjeong-Ku, Busan, 46241, Republic of Korea
| | - Duck-Gyu Lee
- Department of Nature-Inspired Nano Convergence Systems, Korea Institute of Machinery and Materials, 156 Gajeongbuk-Ro, Daejeon, 34103, Republic of Korea
| | - Shin Hur
- Department of Nature-Inspired Nano Convergence Systems, Korea Institute of Machinery and Materials, 156 Gajeongbuk-Ro, Daejeon, 34103, Republic of Korea. .,Nano-Mechatronics, University of Science and Technology, 217 Gajeong-ro, Daejeon, 34103, Republic of Korea.
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Trapped air metamaterial concept for ultrasonic sub-wavelength imaging in water. Sci Rep 2020; 10:10601. [PMID: 32606299 PMCID: PMC7326974 DOI: 10.1038/s41598-020-67454-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 06/01/2020] [Indexed: 11/18/2022] Open
Abstract
Acoustic metamaterials constructed from conventional base materials can exhibit exotic phenomena not commonly found in nature, achieved by combining geometrical and resonance effects. However, the use of polymer-based metamaterials that could operate in water is difficult, due to the low acoustic impedance mismatch between water and polymers. Here we introduce the concept of “trapped air” metamaterial, fabricated via vat photopolymerization, which makes ultrasonic sub-wavelength imaging in water using polymeric metamaterials highly effective. This concept is demonstrated for a holey-structured acoustic metamaterial in water at 200–300 kHz, via both finite element modelling and experimental measurements, but it can be extended to other types of metamaterials. The new approach, which outperforms the usual designs of these structures, indicates a way forward for exploiting additive-manufacturing for realising polymer-based acoustic metamaterials in water at ultrasonic frequencies.
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Lensing in the Ultrasonic Domain using Negative Refraction Induced by Material Contrast. Sci Rep 2019; 9:6368. [PMID: 31019227 PMCID: PMC6482190 DOI: 10.1038/s41598-019-42655-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 04/03/2019] [Indexed: 11/08/2022] Open
Abstract
The focusing of ultrasound using topographic lenses, typically made of plates with step changes that cause an interaction between forward- and backward-propagating guided waves, has been widely studied in recent years. However, such 'step-change' lenses require precise machining and moreover, the thick-thin structure can be unstable during deployment in practical inspection applications. The work reported here follows from the insight that perhaps any approach to induce a mismatch in acoustical impedance as achieved by the step-change can also lead to focusing of ultrasonic guided waves. By carefully choosing the impedance pairing, a novel material contrast lens stacking Aluminium and Molybdenum plates in series is shown to achieve focusing of ultrasound through negative refraction. The interface between the two metals causes the interaction of the forward-propagating second symmetric Lamb mode S2 into the backward- propagating first symmetric S2b. The focusing of Lamb waves is demonstrated using numerical simulations validated by experiments. Comparison with a simple Aluminium-Aluminium plate combination brings out the underlying physics of focusing using the proposed material contrast lens. Simulation results showing super-resolution imaging using the proposed material contrast lens are also presented, demonstrating the power of the proposed approach. This report opens up the possibilities of developing new lensing devices for use in medical imaging and nondestructive evaluation, among other possible applications.
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In-depth study on resonant tunneling for subwavelength imaging. Sci Rep 2018; 8:15535. [PMID: 30341393 PMCID: PMC6195579 DOI: 10.1038/s41598-018-33653-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 10/03/2018] [Indexed: 12/02/2022] Open
Abstract
We report new frequency bands for subwavelength imaging by using the resonant tunneling method which have not been explored previously. As per the existing theory of resonant tunneling, imaging frequency is limited for a certain number of crystals. However, after conducting an analytical analysis over a wide range of frequencies, we observed that higher frequencies do exist for subwavelength imaging. We verified this observation both numerically and experimentally. We extended our study to observe the effect of lattice periodicity on image resolution. By reducing periodicity during experiment, we achieved a resolution of λ/9.5 at the conventional region and λ/2.45 at the higher band region.
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