EP2168210A1 - Method and apparatus for near-field imaging - Google Patents

Method and apparatus for near-field imaging

Info

Publication number
EP2168210A1
EP2168210A1 EP08775449A EP08775449A EP2168210A1 EP 2168210 A1 EP2168210 A1 EP 2168210A1 EP 08775449 A EP08775449 A EP 08775449A EP 08775449 A EP08775449 A EP 08775449A EP 2168210 A1 EP2168210 A1 EP 2168210A1
Authority
EP
European Patent Office
Prior art keywords
evanescent
field
modes
amplitude
resonant
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP08775449A
Other languages
German (de)
French (fr)
Other versions
EP2168210A4 (en
Inventor
Seigei Tretyakov
Stanislav Maslovski
Pekka Alitalo
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Aalto Korkeakoulusaatio sr
Original Assignee
Teknillinen Korkeakoulu
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Teknillinen Korkeakoulu filed Critical Teknillinen Korkeakoulu
Publication of EP2168210A1 publication Critical patent/EP2168210A1/en
Publication of EP2168210A4 publication Critical patent/EP2168210A4/en
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N22/00—Investigating or analysing materials by the use of microwaves or radio waves, i.e. electromagnetic waves with a wavelength of one millimetre or more
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
    • H01Q15/02—Refracting or diffracting devices, e.g. lens, prism
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
    • G01R29/08—Measuring electromagnetic field characteristics
    • G01R29/0864—Measuring electromagnetic field characteristics characterised by constructional or functional features
    • G01R29/0892—Details related to signal analysis or treatment; presenting results, e.g. displays; measuring specific signal features other than field strength, e.g. polarisation, field modes, phase, envelope, maximum value
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
    • G01V3/12—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with electromagnetic waves
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
    • H01Q15/0006—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices
    • H01Q15/0013—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices said selective devices working as frequency-selective reflecting surfaces, e.g. FSS, dichroic plates, surfaces being partly transmissive and reflective
    • H01Q15/0026—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices said selective devices working as frequency-selective reflecting surfaces, e.g. FSS, dichroic plates, surfaces being partly transmissive and reflective said selective devices having a stacked geometry or having multiple layers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
    • H01Q15/0006—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices
    • H01Q15/0086—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices said selective devices having materials with a synthesized negative refractive index, e.g. metamaterials or left-handed materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
    • H01Q15/02—Refracting or diffracting devices, e.g. lens, prism
    • H01Q15/10—Refracting or diffracting devices, e.g. lens, prism comprising three-dimensional array of impedance discontinuities, e.g. holes in conductive surfaces or conductive discs forming artificial dielectric
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q21/00—Antenna arrays or systems
    • H01Q21/06—Arrays of individually energised antenna units similarly polarised and spaced apart
    • H01Q21/061—Two dimensional planar arrays
    • H01Q21/064—Two dimensional planar arrays using horn or slot aerials

Definitions

  • the purpose of our invention is to pick up these rapidly decaying waves, enhance their amplitude, measure it in the invented device in a range of frequencies, and recover the near field picture of a source.
  • the key idea in our invention is that the measurement of the field distribution can be accomplished without any scanning, due to the fact that we propose to use multiple stationary probes which provide enough information to replicate the source field distribution using a post-processing algorithm. In the previously known devices, scanning of the field has been necessary.
  • DNG materials can be realized by using resonant particles or loaded transmission lines. These structures or devices can be called “materials” only in a certain frequency band where the period of the structures is much smaller than the wavelength. Moreover, these structures usually achieve the DNG characteristics only in a very narrow band of frequencies.
  • a source is placed in a DPS material (free space for example) and a slab of a DNG material is placed near this source, an image will form on the other side of the DNG slab, because when the characteristics of the DNG slab are chosen properly, the slab focuses the propagating modes of the source and restores the amplitudes of the evanescent modes in the focal point (i.e., in the image plane).
  • the problem that still remains is the dissipation that occurs in all artificial DNG materials. Especially materials where the DNG properties are based on resonance effects, are very lossy. Because of the strong attenuation inside the DNG material, the amplification of evanescent modes is dramatically reduced.
  • Patents US 2006125681 A1 and WO 03044897 A1 differ significantly from the device discussed here, since their operation is based on volumetric (DNG-) media having exotic effective values of permittivity and permeability, see the discussion above.
  • volumetric media with e.g. negative permittivity or permeability, but instead, one or more sheets possessing certain properties. That is why the patent WO 2006061451 A2 is mostly related to the device discussed here.
  • the physical phenomenon of evanescent wave enhancement is the same in the previous patent and the device discussed here, the physical phenomenon itself is not the target of patenting.
  • the amplification of evanescent modes is achieved by a coupled surface mode resonance that occurs in thin resonant sheets placed in air (effectively, in free space).
  • a coupled surface mode resonance that occurs in thin resonant sheets placed in air (effectively, in free space).
  • the problem of losses inside the material making the lens (between two adjacent resonant sheets) is mitigated, because there is simply no bulk layers of lossy materials in the device. This lowers the overall complexity of the device very much.
  • An advantage is also that either electric or magnetic resonance can be used (or both).
  • a disadvantage is that the device described in this invention cannot operate with propagating modes, but on the other hand the low-resolution imaging with the help of propagating modes is trivial and can be realized with conventional devices.
  • the spatial spectrum can be divided in two parts:
  • the key feature of all these structures is the ability to amplify evanescent waves.
  • the frequency scanning lens described in this report belongs to the third class.
  • ⁇ o( ⁇ , k t ) is the wave impedance of the corresponding free-space plane wave (its different for TE and TM waves).
  • the solutions of this equation are pairs ( ⁇ , k ⁇ ) that lie on grid's dispersion curve. If the grid is periodic with period d « ⁇ 0 (the free-space wavelength) its dispersion curve may look like it is shown in Figure 1.
  • Figure 1 presents an example dispersion curve of a periodic structure.
  • q k t d.
  • Figure 2 gives the side view of a possible lens structure. Two arrays of small particles are positioned along the x-axis. The screening box is open at one of its sides (at the object plane).
  • Figure 4 presents an illustration of a prototype of the proposed device.
  • Figure 5 presents an example device structure illustrating a possible realization of the source.
  • the object to be imaged can be excited at the frequencies in the range [ ⁇ mm , ⁇ max ] and that the properties of the object itself do not change much when we scan the frequency in this range. Practically this means that we have to provide as narrow frequency band of the dispersion curve as possible. This means the same condition that we had in [1]: the particles must be weakly interacting and be high-Q resonators themselves.
  • the meandered metal particles used in [1] and [3] should be good enough because the frequency range where the resonances occurred was really narrow. If the object is passive (for example, it is a small piece of metal) it can be excited with another antenna that illuminates it with a plane wave of the necessary frequency.
  • the object and the illuminating source will not influence the operation of the device (or at least its influence is predictable and can be taken into account in the post-processing stage). It can be a good engineering task to figure out the optimal disposition of the illuminating source(s) and the arrays, etc.
  • the transmission through the lens as a function of k x will look like in Figure 3.
  • the characteristic width of the pike is physically determined by the characteristic size L (array length) of the lens: Ak x « ⁇ /L.
  • L array length
  • the pike can be made as narrow as required.
  • the field sensor will measure a kind of average amplitude of the modes with k xres - ⁇ /f/2 ⁇ I k x ⁇ ⁇ kxres + ⁇ /f x /2.
  • the coeffcient U ⁇ accounts for the spectral density of the modes.
  • FIG. 4 An illustration of a possible prototype of the proposed device is shown in Figure 4.
  • the object to be measured is placed in the object plane.
  • the object is illuminated with a source connected to a vector network analyzer.
  • the source can be e.g. a probe placed inside the measurement setup, as shown in Figure 5.
  • the two adjacent sheets of resonant particles enhance the near-field of the object plane.
  • the field distribution in the object plane can be found by using a post-processing algorithm.
  • the measurement setup must be calibrated in order to find out the spatial profiles of the modes that are supported by the sheets. This calibration can be done e.g. in such a way that the object plane is empty. The important thing is that in the calibration measurement, all the necessary modes are excited on the sheets.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Electromagnetism (AREA)
  • Remote Sensing (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Geology (AREA)
  • Health & Medical Sciences (AREA)
  • Geophysics (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)

Abstract

The invention deals with the problem of identifying small particles or small irregularities in a material. In general, the resolution characteristics of an imaging device could be significantly improved if the device could sense or capture the evanescent part of the spectrum of the incoming wave. It is known that the amplitude of an evanescent wave is attenuated exponentially as a function of the distance from the source. The main principle of operation of the proposed device is to identify and sense these evanescent waves, enhance their amplitude, measure the enhanced field with the invented device in a certain frequency bandwidth and by using a postprocessing algorithm, reconstruct the near-field image of the object. In order to simplify the device and the measurement procedure, a method has been developed that uses only a small number of stationary probes. From the measured results, the original field distribution of the imaged object can be obtained by using a post-processing alorithm.

Description

Method and apparatus for near-field imaging
Purpose of the invention
The problem of detecting small irregularities or objects located in optically opaque materials is of a great practical importance. Many of such materials are transparent (at least, partially) for microwave radiation. Traditional microwave appliances used for the purpose of detection (radars of different operating principles) are limited in resolution. Their spatial resolution is at best of the order of one wavelength of the used microwave radiation.
Recently, it has been found that the resolution of an imaging device can be greatly improved if this device is able to react to the evanescent part of the spatial spectrum of the incident field. As is known, the evanescent waves undergo a rapid (exponential) decay when the distance from the source increases.
The purpose of our invention is to pick up these rapidly decaying waves, enhance their amplitude, measure it in the invented device in a range of frequencies, and recover the near field picture of a source.
The key idea in our invention is that the measurement of the field distribution can be accomplished without any scanning, due to the fact that we propose to use multiple stationary probes which provide enough information to replicate the source field distribution using a post-processing algorithm. In the previously known devices, scanning of the field has been necessary.
Existing solutions
As has been mentioned above, the possibility to enhance evanescent waves of a source would allow imaging with higher resolution than the wavelength. In an ideal case, where all evanescent modes are restored in the image plane, the resolution of the image would be infinitely high. Recently, the double-negative (DNG) or left-handed materials (materials with negative relative permittivity and permeability) has received much attention in the literature. It has been shown that in certain cases a slab made of such materials can enhance the evanescent waves of the source, thus enhancing the maximum achievable resolution. The enhancement of the evanescent waves is based on excitation of surface resonances at the interfaces between double-positive (DPS, a material with positive relative permittivity and permeability) and double-negative materials.
The main problem in implementing such materials is that they do not exist in nature. In the literature it has been shown that DNG materials can be realized by using resonant particles or loaded transmission lines. These structures or devices can be called "materials" only in a certain frequency band where the period of the structures is much smaller than the wavelength. Moreover, these structures usually achieve the DNG characteristics only in a very narrow band of frequencies. If a source is placed in a DPS material (free space for example) and a slab of a DNG material is placed near this source, an image will form on the other side of the DNG slab, because when the characteristics of the DNG slab are chosen properly, the slab focuses the propagating modes of the source and restores the amplitudes of the evanescent modes in the focal point (i.e., in the image plane). The problem that still remains is the dissipation that occurs in all artificial DNG materials. Especially materials where the DNG properties are based on resonance effects, are very lossy. Because of the strong attenuation inside the DNG material, the amplification of evanescent modes is dramatically reduced.
Another problem in the devices proposed in the literature is the fact that in order to obtain a near-field image, the field distribution has to be scanned with a probe of some kind (e.g. in the image plane of a DNG-based superlens). This is actually quite time-consuming and complicated to realize due to the required accuracy of the measurement (a lot of scanning steps are required).
There exist a few patents that are related to the device proposed in the current patent application. These are US 2006125681 A1 , WO 03044897 A1 , and WO 2006061451 A2. Patents US 2006125681 A1 and WO 03044897 A1 differ significantly from the device discussed here, since their operation is based on volumetric (DNG-) media having exotic effective values of permittivity and permeability, see the discussion above. In the device discussed in this document, there is no volumetric media with e.g. negative permittivity or permeability, but instead, one or more sheets possessing certain properties. That is why the patent WO 2006061451 A2 is mostly related to the device discussed here. Although the physical phenomenon of evanescent wave enhancement is the same in the previous patent and the device discussed here, the physical phenomenon itself is not the target of patenting.
Detailed description of the invention
In this invention, the amplification of evanescent modes is achieved by a coupled surface mode resonance that occurs in thin resonant sheets placed in air (effectively, in free space). In this case the problem of losses inside the material making the lens (between two adjacent resonant sheets) is mitigated, because there is simply no bulk layers of lossy materials in the device. This lowers the overall complexity of the device very much. An advantage is also that either electric or magnetic resonance can be used (or both). A disadvantage is that the device described in this invention cannot operate with propagating modes, but on the other hand the low-resolution imaging with the help of propagating modes is trivial and can be realized with conventional devices.
The actual measurements of the enhanced evanescent fields happen in the invented device only at a limited number of points of the image plane. To reconstruct a complete image we use a frequency scanning technique combined with an a priori knowledge of the resonant properties of the device. The resulting image is obtained after a computational step, details of which are described below. The reader should note that since we are mostly interested in the imaging of passive objects, from now on we call the plane that we want to image as object plane, in order to distinguish this plane from a separate source that is used to illuminate a passive object.
Theoretical background
When describing an imaging system it is convenient to apply the Fourier transform. If the electric field distribution at the object plane z = 0 is Et(x, y), then its Fourier transform is
We assume the field being harmonic in time with the frequency ω. Eq. (1) is so-called plane wave expansion, because the electric field after the object plane can be expressed as
Here α = ^k] + ky 2 - kl , 9?(α),3(α)> 0 , and k0 = ω/c (for free space). The spatial spectrum can be divided in two parts:
1. propagating waves: k, = ψc* + ky 2 ≤ &0 (imaginary α)
2. evanescent waves: kt > k0 (real α)
The evanescent waves decay exponentially with the distance. At the moment there are known only a few types of structures that can be used as sub- wavelength lenses/microscopes. We can separate them roughly in three classes:
1. Based on backward-wave materials (Veselago slab or meshes of loaded transmission lines) 2. Based on phase-conjugation (non-linear three-wave mixing)
3. Based on arrays of resonant particles (coupled surface modes)
The key feature of all these structures is the ability to amplify evanescent waves. The frequency scanning lens described in this report belongs to the third class.
Frequency scanning lens
In [1] we introduced a system of two coupled resonant grids or arrays of small inclusions. We showed both theoretically and experimentally that when the transversal wavenumber kt of an incident evanescent wave matches with the propagation factor of grid's surface wave a strong resonance happen. Because of the resonance the amplitude of the evanescent wave in the image plane becomes equal to the amplitude of the incident wave in the object plane.
The matching of the propagation factors happens at certain frequency. Indeed, the dispersion equation for the surface waves on an impedance grid can be written as
z>,*, )+ 70^ = Q (3)
where ηo(ω, kt) is the wave impedance of the corresponding free-space plane wave (its different for TE and TM waves). The solutions of this equation are pairs (ω, k{) that lie on grid's dispersion curve. If the grid is periodic with period d « λ0 (the free-space wavelength) its dispersion curve may look like it is shown in Figure 1.
We see that for an operating frequency ω e [ωmin, ωmaχ] there is only a single resonating kt. Scanning the frequency from ωmin up to ωmax we can sequentially excite the surface modes of all possible kt ranging from 0 to ktmax = π/d. The amplitude of an excited mode will be proportional to the amplitude of the corresponding spectral component of the incident field. Knowing the spatial profile of every surface mode (from the theory or from an initial calibration measurement) we can find the amplitude of the mode from a field measurement done only at a point in the image plane (or at most at a couple of discrete points).
In a finite-size grid the spectrum of surface modes is discrete, i.e. (3) has a finite number of solutions. In this case the field measurement will be done at discrete frequencies. The procedure will be similar to the measurements done in [1]. The only difference is that we do not need to scan fields over the image plane every time as was done in [1].
One thing that is worth noting is that for open structures (not placed in a waveguide) the surface modes with 0 ≤ kt ≤ k0 « π/d are leaky modes, i.e., they radiate into the free space. In [1] we considered lenses infinite along x- and y-directions. In such systems the amount of the power that is radiated by leaky modes is large and the corresponding resonance is of low quality. But, for example, in a metasolenoid [4] even the modes with small values of kt will produce a strong resonant response because of high Q-factor of its resonances (Q is of the order 103).
Another important thing is that in principle we can use just a single resonating grid. The only difficulty here is that the relation between the amplitude of the excited surface mode and the external field will be more complex (with two ideal grids the amplitude in the image plane is the same as in the object plane).
In the following, the invention will be described in detail by the aid of a few examples of its embodiments with reference to the drawings, wherein
Figure 1 presents an example dispersion curve of a periodic structure. On the horizontal axis q = ktd. Figure 2 gives the side view of a possible lens structure. Two arrays of small particles are positioned along the x-axis. The screening box is open at one of its sides (at the object plane).
Figure 3 presents the transmission through the lens at a given frequency as a function of q = kχd.
Figure 4 presents an illustration of a prototype of the proposed device. Figure 5 presents an example device structure illustrating a possible realization of the source.
For clarity, let us consider a lens composed of a couple of linear (oriented along the x-axis) resonating arrays of small electric dipoles placed in between two metal screens: the same system that was used for experimental verification of the evanescent wave enhancement in [1] and [3]. We assume that the dispersion curves of the arrays look like in Figure 1 and the field is measured at the middle point of the image plane at x = 0. To cope with the situation when the x-component of the electric field vanishes at this point for a certain mode it is necessary to have a couple of sensors there: one measures Ex and the other measures the orthogonal component E2 (the longitudinal component). It is also assumed that the array is long so that the spectrum of its modes is practically continuous (this means that we have at least 50 particles in each array). An example geometry of the structure is shown in Figure 2.
Let us assume that the object to be imaged can be excited at the frequencies in the range [ωmm, ωmax] and that the properties of the object itself do not change much when we scan the frequency in this range. Practically this means that we have to provide as narrow frequency band of the dispersion curve as possible. This means the same condition that we had in [1]: the particles must be weakly interacting and be high-Q resonators themselves. The meandered metal particles used in [1] and [3] should be good enough because the frequency range where the resonances occurred was really narrow. If the object is passive (for example, it is a small piece of metal) it can be excited with another antenna that illuminates it with a plane wave of the necessary frequency. Because the structures we use are most effectively excited with the evanescent waves the object and the illuminating source will not influence the operation of the device (or at least its influence is predictable and can be taken into account in the post-processing stage). It can be a good engineering task to figure out the optimal disposition of the illuminating source(s) and the arrays, etc.
For a given frequency ω e [ωmin, ωmax], the transmission through the lens as a function of kx will look like in Figure 3. The characteristic width of the pike is physically determined by the characteristic size L (array length) of the lens: Akx « π/L. In principle the pike can be made as narrow as required. The field sensor will measure a kind of average amplitude of the modes with kxres - Δ/f/2 < I kx \ < kxres + Δ/fx/2.
The device operates as follows. We scan the frequencies from ωmm up to ωmax and store the measured electric field complex amplitudes at every frequency. In the post-processing we use the known spatial profiles of the modes to restore the actual field distribution from the measured field values at e.g. x = 0.
Denoting for even modes: Aeven = Ef"TOr , and for odd modes: A1*" = -[kz{ω)/kx(ω)]E2 semor , the field distribution in the object plane can be expressed as a sum of all modes:
The coeffcient Uπ accounts for the spectral density of the modes.
An illustration of a possible prototype of the proposed device is shown in Figure 4. In this illustration, the object to be measured is placed in the object plane. The object is illuminated with a source connected to a vector network analyzer. The source can be e.g. a probe placed inside the measurement setup, as shown in Figure 5. The two adjacent sheets of resonant particles enhance the near-field of the object plane. With the stationary probes, the field distribution in the object plane can be found by using a post-processing algorithm. To use a post-processing algorithm, the measurement setup must be calibrated in order to find out the spatial profiles of the modes that are supported by the sheets. This calibration can be done e.g. in such a way that the object plane is empty. The important thing is that in the calibration measurement, all the necessary modes are excited on the sheets.
References
In the following articles the main ideas of the invention have been proven to be applicable.
[1] S. I. Maslovski, S. A. Tretyakov, and P. Alitalo, Near-field enhancement and imaging in double planar polariton-resonant structures, J. Appl. Phys., vol. 96, no. 3, pp. 1293(1300, 2004. [2] M. J. Freire and R. Marques, Planar magnetoinductive lens for three- dimensional sub-wavelength imaging, Appl. Phys. Lett, vol. 86, 182505, 2005.
[3] P. Alitalo, S. Maslovski, and S. Tretyakov, Near-field enhancement and imaging in double cylindrical polariton-resonant structures: Enlarging super- lens, Phys. Lett. A, vol. 357, pp. 397(400, 2006.

Claims

Claims
1. Method for field distribution measurement and amplification of evanescent wave modes in electromagnetic near-field imaging, characterized in that the measurement includes the following steps:
- use of multiple, at least three stationary measuring probes
- obtaining the measuring information from each probe
- use of a post-prosessing algorithm to replicate the source field distribution.
2-Apparatus for method for distribution measurement and amplification of evanescent wave modes in electromagnetic near-field imaging according to claim 1 , characterized in that the apparatus consists of advantageously one or more thin resonant sheets, which can be composed for instance of small resonant particles.
3. Apparatus for method for distribution measurement and amplification of evanescent wave modes in electromagnetic near-field imaging according to claims 1 and 2, characterized in that the resonant particles composing the resonant sheets are either electric or magnetic scatterers.
EP08775449.5A 2007-06-14 2008-06-16 Method and apparatus for near-field imaging Withdrawn EP2168210A4 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI20070474A FI20070474L (en) 2007-06-14 2007-06-14 Method and device for near field imaging
PCT/FI2008/000071 WO2008152190A1 (en) 2007-06-14 2008-06-16 Method and apparatus for near-field imaging

Publications (2)

Publication Number Publication Date
EP2168210A1 true EP2168210A1 (en) 2010-03-31
EP2168210A4 EP2168210A4 (en) 2013-09-25

Family

ID=38212331

Family Applications (1)

Application Number Title Priority Date Filing Date
EP08775449.5A Withdrawn EP2168210A4 (en) 2007-06-14 2008-06-16 Method and apparatus for near-field imaging

Country Status (3)

Country Link
EP (1) EP2168210A4 (en)
FI (1) FI20070474L (en)
WO (1) WO2008152190A1 (en)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2382230A (en) * 2001-11-16 2003-05-21 Marconi Corp Plc Radio frequency imaging device
JP2007121268A (en) * 2005-09-29 2007-05-17 Olympus Corp Optical apparatus

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3531893A1 (en) * 1985-09-06 1987-03-19 Siemens Ag METHOD FOR DETERMINING THE DISTRIBUTION OF DIELECTRICITY CONSTANTS IN AN EXAMINATION BODY, AND MEASURING ARRANGEMENT FOR IMPLEMENTING THE METHOD
US5982326A (en) * 1997-07-21 1999-11-09 Chow; Yung Leonard Active micropatch antenna device and array system
WO2003062840A1 (en) * 2002-01-18 2003-07-31 Her Majesty In Right Of Canada As Represented By The Minister Of Industry Antenna array for the measurement of complex electromagnetic fields

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2382230A (en) * 2001-11-16 2003-05-21 Marconi Corp Plc Radio frequency imaging device
JP2007121268A (en) * 2005-09-29 2007-05-17 Olympus Corp Optical apparatus

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of WO2008152190A1 *

Also Published As

Publication number Publication date
WO2008152190A1 (en) 2008-12-18
FI20070474A0 (en) 2007-06-14
FI20070474L (en) 2008-12-15
EP2168210A4 (en) 2013-09-25

Similar Documents

Publication Publication Date Title
Capolino Applications of metamaterials
Fromenteze et al. Computational imaging using a mode-mixing cavity at microwave frequencies
Maslovski et al. Near-field enhancement and imaging in double planar polariton-resonant structures
Baena et al. Near-perfect tunneling and amplification of evanescent electromagnetic waves in a waveguide filled by a metamaterial: Theory and experiments
Veselago et al. Negative refractive index materials
Holloway et al. A discussion on the interpretation and characterization of metafilms/metasurfaces: The two-dimensional equivalent of metamaterials
Gollub et al. Experimental characterization of magnetic surface plasmons on metamaterials with negative permeability
US20120086463A1 (en) Metamaterial Particles for Near-Field Sensing Applications
Wiltshire Radio frequency (RF) metamaterials
Driscoll et al. Electromagnetic characterization of planar metamaterials by oblique angle spectroscopic measurements
Freire et al. Near-field imaging in the megahertz range by strongly coupled magnetoinductive surfaces: Experiment and ab initio analysis
Popa et al. Direct measurement of evanescent wave enhancement inside passive metamaterials
Wongkasem et al. Novel broadband terahertz negative refractive index metamaterials: Analysis and experiment
Ourir et al. Far field subwavelength imaging of magnetic patterns
Smith et al. Characterization of a planar artificial magnetic metamaterial surface
Campione et al. Magnetoinductive waves and complex modes in two-dimensional periodic arrays of split ring resonators
Jouvaud et al. Far-field imaging with a multi-frequency metalens
Zhao et al. Direct observation of photonic jets and corresponding backscattering enhancement at microwave frequencies
Alitalo et al. Near-field enhancement and imaging in double cylindrical polariton-resonant structures: Enlarging superlens
Markley et al. Meta-screens and near-field antenna-arrays: A new perspective on subwavelength focusing and imaging
EP2168210A1 (en) Method and apparatus for near-field imaging
Shafi et al. Super-resolution microwave imaging using small loop loaded with spiral resonator
Kissel et al. Superresolution in left-handed composite structures: From homogenization to a detailed electrodynamic description
Aghanejad et al. Avoiding imaging artifacts from resonant modes in metamaterial superlenses
Datta et al. Microwave imaging sensor system using metamaterial lens for subwavelength resolution

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 20100108

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MT NL NO PL PT RO SE SI SK TR

AX Request for extension of the european patent

Extension state: AL BA MK RS

DAX Request for extension of the european patent (deleted)
A4 Supplementary search report drawn up and despatched

Effective date: 20130823

RIC1 Information provided on ipc code assigned before grant

Ipc: H01Q 15/02 20060101AFI20130819BHEP

Ipc: G01N 22/00 20060101ALI20130819BHEP

Ipc: G01V 3/12 20060101ALI20130819BHEP

Ipc: G01R 29/08 20060101ALI20130819BHEP

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20140321