scholarly journals Acoustic Focusing with Intensity Modulation Based on Sub-Wavelength Waveguide Array

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1461
Author(s):  
Mingran Zhang ◽  
Guangrui Gu
Keyword(s):  
Focal Length ◽  
Intensity Modulation ◽  
Waveguide Array ◽  
Refractive Index Modulation ◽  
Destructive Testing ◽  
Equivalent Impedance ◽  
Coding Method ◽  
Acoustic Focusing ◽  
Arbitrary Amplitude ◽  
Sub Wavelength

Acoustic focusing with intensity modulation plays an important role in biomedical and life sciences. In this work, we propose a new approach for simultaneous phase and amplitude manipulation in sub-wavelength coupled resonant units, which has not been reported so far. Based on the equivalent impedance and refractive index modulation induced by the change of geometry, arbitrary amplitude response from 0 to 1 and phase shift from 0 to 2π is realized. Thus, the acoustic focusing with intensity modulation can be achieved via waveguide array. Herein, the focal length can be adjusted by alternating the length of supercell, and the whole system can work in a broadband of 0.872f0–1.075f0. By introducing the coding method, the thermal viscosity loss is reduced, and the wavefront modulation can be more accurate. Compared with previous works, our approach has the advantages of simple design and broadband response, which may have promising applications in acoustic communication, non-destructive testing, and acoustic holography.

Simulation study of acoustic refraction wave manipulation based on sub-wavelength artificial periodic structure

2020 ◽  
pp. 2150082
Author(s):  
Shuai Tang ◽  
Jianning Han
Keyword(s):  
Acoustic Wave ◽  
Steel Plate ◽  
Three Dimensional ◽  
Unit Cell ◽  
Asymmetric Transmission ◽  
Plate Structures ◽  
Coding Method ◽  
Acoustic Focusing ◽  
Unit Cells ◽  
Sub Wavelength

We proposed a kind of unit cell composed of simple steel plate structures in this work. A variety of acoustic phenomena including anomalous refraction, asymmetric transmission, acoustic splitting and acoustic focusing were realized by coding the unit cells with different splicing modes. The transformation from plane acoustic wave to vortex acoustic wave was also realized by using the coding method of three-dimensional rotation. This work increased the functionality of the unit cell and provided a method for the design of sub-wavelength acoustic devices.

scholarly journals Metadevice for intensity modulation with sub-wavelength spatial resolution

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Pablo Cencillo-Abad ◽  
Nikolay I. Zheludev ◽  
Eric Plum
Keyword(s):  
Spatial Resolution ◽  
Intensity Modulation ◽  
Sub Wavelength

scholarly journals A Microlens Super-Surface Film with Regular Graded Circular Hole-Like Subwavelength Structures for Highly Focusing Strength

Coatings ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 776
Author(s):  
Jinshuang Wu ◽  
Leimengting Zhang ◽  
Yahong Li ◽  
Yixin Zhang ◽  
Bowei Yang ◽  
...  
Keyword(s):  
Circular Hole ◽  
Focal Length ◽  
Surface Film ◽  
Subwavelength Structures ◽  
Lens Array ◽  
Direct Laser ◽  
Short Focal Length ◽  
Micro Lens Array ◽  
Micro Lens ◽  
Sub Wavelength

Using the fact that a sub-wavelength structure exhibits the same thermal expansion coefficient as a micro-lens array, we design a micro-lens super-surface film with regular circular hole-like subwavelength structures to realize the high performances of central highly focusing strength and short focal length. In addition, based on the Fresnel—Kirchhoff diffraction theory, the influences of subwavelength structural period and height on the focusing performance of a micro-lens are analyzed. Furthermore, the finite-difference time-domain method is utilized to optimize the structural parameters. Via direct laser writing and an inductively coupled plasma process, we fabricated a square micro-lens array consisting of a 1000 × 1000 micro-lens unit with a sub-wavelength structure, and the optical focusing performance was measured in the visible light band. Finally, the experimental results indicate that the focal length is decreased to 15 μm, the focal spot central energy is increased by 7.3%, and the light transmission, enhanced via inserting sub-wavelength structures, corresponds to 3%. This proves that the designed micro-lens array with a regular-graded circular hole-like subwavelength structure can achieve central high focusing and a short focal length. This has applications in several fields of wavefront detection and light field imaging systems.

scholarly journals Metasurface transformation for surface wave control

2015 ◽  
Vol 373 (2049) ◽  
pp. 20140355 ◽  
Author(s):  
E. Martini ◽  
M. Mencagli ◽  
S. Maci
Keyword(s):  
Surface Wave ◽  
Boundary Conditions ◽  
Surface Waves ◽  
Plane Waves ◽  
Transformation Optics ◽  
Microwave Frequencies ◽  
Dielectric Substrates ◽  
Equivalent Impedance ◽  
Sub Wavelength ◽  
Wave Control

Metasurfaces (MTSs) constitute a class of thin metamaterials used for controlling plane waves and surface waves (SWs). At microwave frequencies, they are constituted by a metallic texture with elements of sub-wavelength size printed on thin grounded dielectric substrates. These structures support the propagation of SWs. By averaging the tangential fields, the MTSs can be characterized through homogenized isotropic or anisotropic boundary conditions, which can be described through a homogeneous equivalent impedance. This impedance can be spatially modulated by locally changing the size/orientation of the texture elements. This allows for a deformation of the SW wavefront which addresses the local wavevector along not-rectilinear paths. The effect of the MTS modulation can be analysed in the framework of transformation optics. This article reviews theory and implementation of this MTS transformation and shows some examples at microwave frequencies.

scholarly journals Investigations on Practical Issues in Solid Immersion Lens Based Sub-Wavelength Terahertz Imaging Technique: System Stability Verification and Interference Pattern Removal

Sensors ◽  
2021 ◽  
Vol 21 (21) ◽  
pp. 6990
Author(s):  
Da-Hye Choi ◽  
Jun-Hwan Shin ◽  
Il-Min Lee ◽  
Kyung Hyun Park
Keyword(s):  
Imaging Techniques ◽  
Imaging Systems ◽  
System Stability ◽  
Objective Lens ◽  
Solid Immersion Lens ◽  
Thz Imaging ◽  
Destructive Testing ◽  
Wide Range ◽  
Surface Profiles ◽  
Sub Wavelength

Terahertz (THz) imaging techniques are attractive for a wide range of applications, such as non-destructive testing, biological sensing, and security imaging. We investigate practical issues in THz imaging systems based on a solid immersion lens (SIL). The system stability in terms of longitudinal misalignment of the SIL is experimentally verified by showing that the diffraction-limited sub-wavelength beam size (0.7 λ) is maintained as long as the SIL is axially located within the depth-of-focus (~13 λ) of the objective lens. The origin of the fringe patterns, which are undesirable but inevitable in THz imaging systems that use continuous waves, is analytically studied, and a method for minimizing the interference patterns is proposed. By combining two THz images obtained at different axial positions of the object and separated by λ/4, the interference patterns are significantly reduced, and the information hidden under the interference patterns is unveiled. The broad applicability of the proposed method is demonstrated by imaging objects with different surface profiles. Our work proves that the resolution of conventional THz imaging systems can easily be enhanced by simply inserting a SIL in front of the object with high tolerance in the longitudinal misalignment and provides a method enabling THz imaging for objects with different surface profiles.

scholarly journals Electromagnetic Micro-Structure Non-Destructive Testing: Sparsity-Constrained and Combined Convolutional Recurrent Neural Network Methods

Electronics ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1750
Author(s):  
Peipei Ran ◽  
Dominique Lesselier ◽  
Mohammed Serhir
Keyword(s):  
Neural Networks ◽  
Super Resolution ◽  
Expansion Method ◽  
Non Destructive Testing ◽  
Micro Structure ◽  
Destructive Testing ◽  
Network Methods ◽  
Finite Set ◽  
Non Destructive ◽  
Sub Wavelength

How to locate missing rods within a micro-structure composed of a grid-like, finite set of infinitely long circular cylindrical dielectric rods under the sub-wavelength condition is investigated. Sub-wavelength distances between adjacent rods and sub-wavelength rod diameters require super-resolution, beyond the Rayleigh criterion. Two different methods are proposed to achieve this: One builds upon the multiple scattering expansion method (MSM), and it enforces strong sparsity-prior information. The other is a data-driven method that combines convolutional neural networks (CNN) and recurrent neural networks (RNN), and it can be applied in effect with little knowledge of the wavefield interactions involved, in much contrast with the previous one. Comprehensive numerical simulations are proposed in terms of the missing rod number, shape, the frequency of observation, and the configuration of the tested structures. Both methods are shown to achieve suitable detection, yet under more or less stringent conditions as discussed.

Design of All-Dielectric Long-wave infrared Wide-angle Metalens

2021 ◽  
Author(s):  
Ning Zhang ◽  
Qingzhi Li ◽  
Jun Chen ◽  
Feng Tang ◽  
Jingjun Wu ◽  
...  
Keyword(s):  
Focal Length ◽  
Low Cost ◽  
Numerical Aperture ◽  
Single Layer ◽  
Industrial Processing ◽  
Monochromatic Imaging ◽  
Long Wave ◽  
Wavelength Scale ◽  
Long Wave Infrared ◽  
Sub Wavelength

Abstract Optical metasurfaces are two-dimensional arrays of nano-scatterers that modify optical wavefronts at subwavelength spatial resolution. They achieve the effect of focusing through phase control under a sub-wavelength scale, named metalens. They are poised to revolutionize optics by enabling complex low-cost systems. However, there are monochromatic severe aberrations in the metasurfaces. In this paper,the long-wave infrared optical system coma is eliminated through a single-layer metasurface. By changing the phase function,this metalens have a numerical aperture of 0.89,a focal length of 150 μm,and a field of view of 120° (0.4@60lp/mm) that enables diffraction-limited monochromatic imaging along the focal plane at a wavelength of 10.6μm. And the designed metasurface maintains a favorable MTF value at different angles. This equipment can be widely used in imaging and industrial processing.

Acoustic focusing of sub-wavelength scale achieved by multiple Fabry-Perot resonance effect

2014 ◽  
Vol 115 (10) ◽  
pp. 104504 ◽  
Author(s):  
Zhou Lin ◽  
Xiasheng Guo ◽  
Juan Tu ◽  
Jianchun Cheng ◽  
Junru Wu ◽  
...  
Keyword(s):  
Resonance Effect ◽  
Fabry Perot ◽  
Acoustic Focusing ◽  
Wavelength Scale ◽  
Sub Wavelength

scholarly journals ABOUT TECHNOLOGIES OF X-RAY SYSTEMS FOR CONTROL OF ELECTRONIC COMPONENTS

2019 ◽  
Vol 22 (3) ◽  
pp. 113-121
Author(s):  
Anatoly I. Mazurov ◽  
Nikolay N. Potrakhov
Keyword(s):  
Focal Length ◽  
Inspection System ◽  
Electronic Components ◽  
Destructive Testing ◽  
X Ray ◽  
Advantages And Disadvantages ◽  
Pumping System ◽  
Inspection Systems ◽  
The Cost ◽  
Non Destructive

Introduction. X-ray methods are currently widely used in manufacturing of various products and components of the electronics industry, including micro- and nano-electronics. One of the most informative and illustrative methods is projection X-ray microscopy. Specialized X-ray systems for process control are developed and used in industry. The key element in the design of an X-ray inspection system is an X-ray tube. In the overwhelming majority of cases, X-ray inspection systems are based on collapsible microfocus x-ray tubes with constant pumping. This greatly complicates the design of the installation, increases its dimensions, weight and cost. Objective. Analysis of possible technical and technological solutions that improve the availability of the X-ray system for monitoring of electronic components while maintaining the information content of the control. Materials and methods. The article presents the results of analytical studies of assessment of the degree of influence of the main parameters of the X-ray tube – the size of the focal spot and the focal length – on the resolution of the resulting X-ray images. The advantages and disadvantages of two variants of the construction of the X-ray inspection systems are described: based on collapsible and based on sealed X-ray tubes. The dependence of the size of the focal spot on the voltage on the X-ray tube and on the power supplied by the electron beam to the target of the X-ray tube is analyzed. It is shown that sealed (from a vacuum pumping system) micro focus X-ray tubes can be successfully used as a radiation source in installations for X-ray inspection. It is concluded that in most cases, sealed tubes are more practical. Results. In solving of most problems of non-destructive testing of electronic components in the composition of the Xray system, X-ray sources based on sealed X-ray tubes can be successfully used. Due to this, dimensions, weight, and the cost of an X-ray system for monitoring of electronic components are substantially reduced. Conclusion. Sealed X-ray tubes are an effective alternative in the development of an X-ray system for monitoring of electronic components, which enables to fundamentally increase the availability of such a system.

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