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Multifoci acoustic field generation: (a) hologram profile plotted by matlab; (b) simulated acoustic field in the x-z plane; (c) simulated acoustic field in the x-y plane; (d) measured acoustic field in the x-y plane; (e) measured acoustic field in the x-y plane; (f) measured acoustic field in the x-y plane.
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This paper reported a method for designing monolithic acoustic holograms with consideration of both amplitude and phase modulation, which can be used for multifocal point beam forming by a single element ultrasonic transducer in the frequency of megahertz range. Mask-image-projection-based stereolithography 3D printing technology was induced to man...
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... designed holograms for the multi-foci and letter pat- tern are shown in Figs. 3 and 4, with a spacing grid of 200 lm. The diameter of the hologram area is 30 mm, the same as the transducer element. The nine points in the focal plane were set with a spacing of 8 mm, covering an area of 16 Â 16 mm 2 . The focal plane was set 60 mm away from the front of the surface. From the simulated acoustic field in Figs. 4(b) and ...
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... measured acoustic field is shown in Figs. 4(d) and 5(d). In both cases, the designed pattern U and nine points have been clearly realized and the two show excellent agree- ment with the simulated field in the overall shape of the pat- tern. In order to check the uniformity of the generated pattern, the focal tightness of nine points in horizontal and vertical axes is plotted in ...
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... in Figs. 4(d) and 5(d). In both cases, the designed pattern U and nine points have been clearly realized and the two show excellent agree- ment with the simulated field in the overall shape of the pat- tern. In order to check the uniformity of the generated pattern, the focal tightness of nine points in horizontal and vertical axes is plotted in Figs. 4(e) and 4(f). It is obvious that the intensities of nine points were equally ...
Similar publications
Evolvable acoustic fields are considered an effective method for solving technical problems related to fields such as biological imaging, particle manipulation, drug therapy and intervention. However, because of technical difficulties and the limited technology available for realizing flexible adjustments of sound fields, few studies have reported...
Citations
... Although it offers more freedom by controlling both the amplitude and the phase, the design of a metasurface-based hologram with decoupled (or quasi-decoupled) PAM is subject to its microstructure configuration and size with possible lack of precision and flexibility. Differently, Zhang et al. 19 introduced a modified weighted Gerchberg-Saxton algorithm to design monolithic acoustic holograms with consideration of PAM. A nine foci pattern and an image of the letter "U" were shown by a 2 MHz transducer attached to the holograms with the designed thickness profiles. ...
Unlike the holography technique using active sound source arrays, metasurface-based holography can avoid cumbersome circuitry and only needs a single transducer. However, a large number of individually designed elements with unique amplitude and phase modulation capabilities are often required to obtain a high-quality holographic image, which is a non-trivial task. In this paper, the deep-learning-aided inverse design of an acoustic metasurface-based hologram with millions of elements to reconstruct megapixel pictures is reported. To improve the imaging quality, an iterative compensation algorithm is proposed to remove the interference fringes and unclear details of the images. A megapixel image of Mona Lisa's portrait is reconstructed by a 2000 × 2000 metasurface-based hologram. Finally, the design is experimentally validated by a metasurface consisting 30 × 30 three-dimensional printed elements that can reproduce the eye part of Mona Lisa's portrait. It is shown that the sparse arrangement of the elements can produce high-quality images even when the metasurface has fewer elements than the targeted image pixels.
... A typical acoustic focusing method involves the alignment of a planar transducer with an acoustic lens, which can be fabricated from plastic, epoxy, rubber, or liquid. It refracts sound using the same basic law as optical lenses [12]. In this study, we developed a multifocal acoustic radiation force source using a combination of a single-element transducer and a 3D-printed acoustic lens array. ...
In this study, we introduce a multifocal acoustic radiation force source that combines an ultrasound transducer and a 3D-printed acoustic lens for application in reverberant optical coherence elastography (Rev-OCE). An array of plano–concave acoustic lenses, each with an 11.8 mm aperture diameter, were used to spatially distribute the acoustic energy generated by a 1 MHz planar ultrasound transducer, producing multiple focal spots on a target plane. These focal spots generate reverberant shear wave fields detected by the optical coherence tomography (OCT) system. The effectiveness of the multifocal Rev-OCE system in probing mechanical properties with high resolution is demonstrated in layered gelatin phantoms.
... The build orientation is frequently one of the most powerful aspects determining the mechanical properties of fabricated components and one of the few that is present in practically all additive manufacturing (AM) procedures [16] . Stereolithography (SLA), rapid fabrication, high-resolution process, and dimensional accuracy for additive manufacturing (AM) [17] . Other 3D printing processes could not produce fine details, and complicated geometries and SLA could. ...
... Conventionally, an iterative angular spectrum approach (IASA) [15], which is basically the Gerchberg-Saxton algorithm [16], is used for generation of acoustic holograms [1], [17]. However, the IASA showed limited performance, and thus, many studies proposed modified methods based on the IASA, including iterative backpropagation [5], weighted Gerchberg-Saxton [18], both phase and amplitude modulation [19], and stacked or multifrequency hologram methods [20], [21]. Recently, even the automatic differentiation technique, used for machine learning, was exploited in a manner similar to that used in IASA to enhance the acoustic field reconstruction performance [22]. ...
Acoustic holography has been gaining attention for various applications such as non-contact particle manipulation, non-invasive neuromodulation, and medical imaging. However, only a few studies on how to generate acoustic holograms have been conducted, and even conventional acoustic hologram algorithms show limited performance in the fast and accurate generation of acoustic holograms, thus hindering the development of novel applications. We here propose a deep learning-based framework to achieve fast and accurate acoustic hologram generation. The framework has an autoencoder-like architecture; thus the unsupervised training is realized without any ground truth. For the framework, we demonstrate a newly developed hologram generator network, the Holographic Ultrasound generation Network (HU-Net), which is suitable for unsupervised learning of hologram generation, and a novel loss function that is devised for energy-efficient holograms. Furthermore, for considering various hologram devices (i.e., ultrasound transducers), we propose a physical constraint layer. Simulation and experimental studies were carried out for two different hologram devices such as a 3D printed lens, attached to a single element transducer, and a 2D ultrasound array. The proposed framework was compared with the iterative angular spectrum approach (IASA) and the state-of-the-art iterative optimization method, Diff-PAT. In the simulation study, our framework showed a few hundred times faster generation speed, along with comparable or even better reconstruction quality, than those of IASA and Diff-PAT. In the experimental study, the framework was validated with 3D-printed lenses fabricated based on different methods, and the physical effect of the lenses on the reconstruction quality was discussed. The outcomes of the proposed framework in various cases (i.e., hologram generator networks, loss functions, hologram devices) suggest that our framework may become a very useful alternative tool for other existing acoustic hologram applications and it can expand novel medical applications.
... Another promising approach is to place an acoustic lens in front of a single-element transducer to correct the skullinduced beam aberration. The thickness profile of the acoustic lens is derived from the phase profile obtained by numerical simulation of transcranial wave propagation from the targeted point Zhang et al., 2018;Zhu and Assouar, 2019;Brown et al., 2020;Kim et al., 2021). The acoustic lens is then 3D printed, which provides a low-cost and easy-toimplement solution to compensate for the skull aberration. ...
Transcranial focused ultrasound (tFUS) is a promising technique for non-invasive and spatially targeted neuromodulation and treatment of brain diseases. Acoustic lenses were designed to correct the skull-induced beam aberration, but these designs could only generate static focused ultrasound beams inside the brain. Here, we designed and 3D printed binary acoustic metasurfaces (BAMs) for skull aberration correction and dynamic ultrasound beam focusing. BAMs were designed by binarizing the phase distribution at the surface of the metasurfaces. The phase distribution was calculated based on time reversal to correct the skull-induced phase aberration. The binarization enabled the ultrasound beam to be dynamically steered along wave propagation direction by adjusting the operation frequency of the incident ultrasound wave. The designed BAMs were manufactured by 3D printing with two coding bits, a polylactic acid unit for bit “1” and a water unit for bit “0.” BAMs for single- and multi-point focusing through the human skull were designed, 3D printed, and validated numerically and experimentally. The proposed BAMs with subwavelength scale in thickness are simple to design, easy to fabric, and capable of correcting skull aberration and achieving dynamic beam steering.
... Due to its powerful and flexible capability of arbitrary sound beam shaping and predesigned sound field reconstruction, acoustic holography has recently received increased attention in many interdisciplinary fields related to acoustics, including medicine [3][4][5][6], engineering [7,8], and biology [9][10][11], in addition to the pure acoustic field. Many applications have been made possible by acoustic holography, including acoustic fabrication [7], beam shaping [12][13][14][15][16][17][18][19][20], acoustic holographic imaging [3,[15][16][17][18][19][20][21][22][23][24][25][26][27][28], volumetric display [29,30], volumetric haptics [31,32], particle manipulation [11,21,26,33,34], 3D ultrasound imaging [8], cell manipulation [9,10], characterizing medical ultrasounds [4,5], neurostimulation and neuromodulation [6], and energy transfer [25]. ...
... Due to its powerful and flexible capability of arbitrary sound beam shaping and predesigned sound field reconstruction, acoustic holography has recently received increased attention in many interdisciplinary fields related to acoustics, including medicine [3][4][5][6], engineering [7,8], and biology [9][10][11], in addition to the pure acoustic field. Many applications have been made possible by acoustic holography, including acoustic fabrication [7], beam shaping [12][13][14][15][16][17][18][19][20], acoustic holographic imaging [3,[15][16][17][18][19][20][21][22][23][24][25][26][27][28], volumetric display [29,30], volumetric haptics [31,32], particle manipulation [11,21,26,33,34], 3D ultrasound imaging [8], cell manipulation [9,10], characterizing medical ultrasounds [4,5], neurostimulation and neuromodulation [6], and energy transfer [25]. ...
... The algorithms used include the iterative angular spectrum approach [21], the iterative backpropagation algorithm [33], the weighted Gerchberg-Saxton algorithm [20], the pseudo-inverse method [36], the conjugate field method [37], the deep learning method [35], and so on. Physically, these calculated maps are realized by either discrete and independently driven elements of active phasedarray emitters [3][4][5][27][28][29][30][31][32][33][34] (such as loudspeakers in the air or piezoelectric transducers in water) or meta-pixels of passive acoustic metasurfaces [6][7][8][9][12][13][14][15][16][17][18][19][20][21][22][23][24][25]38], or a combination of both [26]. In the reconstruction process, these acoustic holographic devices with the required phase and/or amplitude distributions diffract sound waves to form the desired real image in the pre-designed image plane. ...
Acoustic holography is an essential tool for controlling sound waves, generating highly complex and customizable sound fields, and enabling the visualization of sound fields. Based on acoustic sieve metasurfaces (ASMs), this paper proposes a theoretical design approach for zero-thickness broadband holograms. The ASM is a zero-thickness rigid screen with a large number of small holes that allow sound waves to pass through and produce the desired real image in the target plane. The hole arrangement rules are determined using a genetic algorithm and the Rayleigh–Sommerfeld theory. Because the wave from a hole has no extra phase or amplitude modulation, the intractable modulation dispersion can be physically avoided, allowing the proposed ASM-based hologram to potentially function in any frequency band as long as the condition of paraxial approximation is satisfied. Using a numerical simulation based on the combination of the finite element method (FEM) and the boundary element method (BEM), this research achieves broadband holographic imaging with a good effect. The proposed theoretical zero-thickness broadband hologram may provide new possibilities for acoustic holography applications.
... Bakhtiari-Neiad et al. [306] designed a phase-shifting hologram for waterborne ultrasound by using an iterative angular spectrum approach; and a multifocal pressure pattern was generated by the hologram. Zhang et al. [307] introduced a modified weighted Gerchberg-Saxton method for monolithic acoustic hologram design in which both amplitude and phase modulation were considered. Multifocal and letter "U" fields were generated for waterborne sound. ...
... By doing so, the letters "UCL" with the uniform amplitude were achieved experimentally. The phase-amplitude modulation provides more design space for holograms [307,308]. However, the coupling of phase and amplitude brings some difficulties in design; and generally, optimization methods should be utilized. ...
Acoustic/elastic metasurfaces as a kind of two-dimensional metamaterials are of subwavelength thickness and show remarkable ability of acoustic/elastic wave manipulation. They have potential applications in various fields such as acoustic imaging, communications, cloaking, camouflage, vibration/noise control, energy harvesting, nondestructive testing, etc. In this review, we mainly summarize recent developments in acoustic/elastic phase gradient metasurfaces, including design principles, design of functional elements, wave field manipulation with applications, design of tunable metasurfaces, as well as the emerging digital coding metasurfaces. At last, we outline the future research directions in this field.
... Quantum optics and smart optical interaction devices will be major research direction in the 3D printing of optics. Moreover, functional components such as lens, waveguide, LED, photonics, and SCs, will open new opportunities for develop advanced optical devices for various applications, including aerospace, biomedical engineering, computational imaging, energy harvest, camouflage [158][159][160][161]. ...
Various kinds of optical devices have been designed for unique functionality based on a deeper understanding of optical principles. Recently, the research of functional optics has become a hot topic due to their wide usage in diverse fields. However, the structural complexity and multi-material distribution of advanced optical devices far exceed the fabrication capability of traditional manufacturing techniques, which inevitably hinders the further development of functional optics for various promising applications. As a revolutionary advanced manufacturing technology, additive manufacturing (AM) has demonstrated its potential to produce multi-material, multi-scale and multi-functional optical devices for excellent performance in imaging, sensing, displaying, and light modulating. Here, recent achievements in additive manufacturing of functional optics including lens, optoelectronics, photonics, and metamaterials were reviewed. The investigation covers the design scenarios, material selection, 3D printing strategies, and property evaluation. Current challenges, prospective research topics, and future promising applications of 3D printing of next-generation functional optics are discussed at the end.
... During the epoxy curing cycle of 5 min, the standing wave was activated and diamond nanoparticles migrated toward the nodes due to acoustic radiation force and formed quasi-parallel planes of particle clusters ( Figure 5A) [150]. Complex particle-polymer composite structures can be formed using SAWs if the acoustic signal is first passed through a pattern that acts like a "hologram" for the desired structure (e.g., Figure 5B) [151][152][153]. Localizing particles at the node has be done by adjusting the input voltage into the piezoelectric transducer, which linearly scales with applied pressure amplitude [156]. ...
Particle-polymer dispersions are ubiquitous in additive manufacturing (AM), where they are used as inks to create composite materials with applications to wearable sensors, energy storage materials, and actuation elements. It has been observed that directional alignment of the particle phase in the polymer dispersion can imbue the resulting composite material with enhanced mechanical, electrical, thermal or optical properties. Thus, external field-driven particle alignment during the AM process is one approach to tailoring the properties of composites for end-use applications. This review article provides an overview of externally directed field mechanisms (e.g., electric, magnetic, and acoustic) that are used for particle alignment. Illustrative examples from the AM literature show how these mechanisms are used to create structured composites with unique properties that can only be achieved through alignment. This article closes with a discussion of how particle distribution (i.e., microstructure) affects mechanical properties. A fundamental description of particle phase transport in polymers could lead to the development of AM process control for particle-polymer composite fabrication. This would ultimately create opportunities to explore the fundamental impact that alignment has on particle-polymer composite properties, which opens up the possibility of tailoring these materials for specific applications.
... [1] 초음파 홀로그램을 이용하 면 입자를 조작하고, 입자를 모아 모양을 만들며, 여러 위치의 신경에 동시에 자극을 줄 수도 있다. [2][3][4][5] 초음파 홀로그램은 배열형 변환자의 각 소자에서 송신 신호의 위상을 조절하거나, [6,7] 단일 소자 변환 자에 위상 조절 렌즈를 붙임으로써 [8,9] ...
Recently, an ultrasound hologram and its applications have gained attention in the ultrasound research field. However, the determination technique of transmit signal phases, which generate a hologram, has not been significantly advanced from the previous algorithms which are time-consuming iterative methods. Thus, we applied the deep learning technique, which has been previously adopted to generate an optical hologram, to generate an ultrasound hologram. We further examined the Deep learning-based Holographic Ultrasound Generation algorithm (Deep-HUG). We implement the U-Net-based algorithm and examine its generalizability by training on a dataset, which consists of randomly distributed disks, and testing on the alphabets (A-Z). Furthermore, we compare the Deep-HUG with the previous algorithm in terms of computation time, accuracy, and uniformity. It was found that the accuracy and uniformity of the Deep-HUG are somewhat lower than those of the previous algorithm whereas the computation time is 190 times faster than that of the previous algorithm, demonstrating that Deep-HUG has potential as a useful technique to rapidly generate an ultrasound hologram for various applications.
