阅读说明：本技术 使用超材料的光学成像设备及使用超材料的光学成像方法 (Optical imaging apparatus using metamaterial and optical imaging method using metamaterial ) 是由 徐旻我 李尚训 金哲基 金哉宪 李宅振 禹德夏 于 2020-03-03 设计创作，主要内容包括：本发明的一个实施例提供了一种使用超材料的光学成像设备,该光学成像设备包括：超材料阵列传感器,该超材料阵列传感器包括由超材料制成的多个单位晶格并与观察对象相邻放置；成像光束提供单元,该成像光束提供单元向超材料阵列传感器提供成像光束；控制光束提供单元,该控制光束提供单元控制提供至单位晶格的控制光束以阻挡入射在单位晶格上的成像光束；以及成像光束测量单元,该成像光束测量单元通过测量当成像光束穿过单位晶格时超材料阵列传感器的成像光束透射量和当控制光束聚焦在单位晶格上以阻挡入射在单位晶格上的成像光束时超材料阵列传感器的成像光束透射量来测量穿过单位晶格的单位晶格成像光束透射量。(An embodiment of the present invention provides an optical imaging apparatus using a metamaterial, the optical imaging apparatus including: a metamaterial array sensor including a plurality of unit cells made of a metamaterial and disposed adjacent to an observation object; an imaging beam providing unit that provides an imaging beam to the metamaterial array sensor; a control beam supply unit that controls a control beam supplied to the unit cell to block an imaging beam incident on the unit cell; and an imaging beam measuring unit that measures a unit cell imaging beam transmission amount through the unit cell by measuring an imaging beam transmission amount of the metamaterial array sensor when the imaging beam passes through the unit cell and an imaging beam transmission amount of the metamaterial array sensor when the control beam is focused on the unit cell to block the imaging beam incident on the unit cell.)

1. An optical imaging apparatus using metamaterials, the optical imaging apparatus comprising:

a metamaterial array sensor including a plurality of unit cells made of a metamaterial and placed adjacent to an observation object;

an imaging beam providing unit that provides an imaging beam to the metamaterial array sensor;

a control beam supply unit that controls a control beam supplied to the unit cell to block the imaging beam incident on the unit cell; and

an imaging beam measurement unit that measures a unit cell imaging beam transmission amount through the unit cell by measuring an imaging beam transmission amount of the metamaterial array sensor when the imaging beam passes through the unit cell and an imaging beam transmission amount of the metamaterial array sensor when the control beam is focused on the unit cell to block the imaging beam incident on the unit cell.

2. The optical imaging apparatus according to claim 1, further comprising an image acquisition unit that acquires an optical analysis image of the observation object by using the unit cell imaging beam transmission amount measured by the imaging beam measurement unit with respect to each of the plurality of unit cells, the optical analysis image having a spatial resolution corresponding to a size of the metamaterial constituting the unit cell.

3. The optical imaging apparatus of claim 1, wherein a size of the metamaterial comprising the unit cell is less than a diffraction limit of the imaging beam.

4. The optical imaging apparatus of claim 1, wherein the control beam has a spot size preset to correspond to a size of the metamaterial making up the unit cell.

5. The optical imaging apparatus of claim 1, wherein the imaging light beam is in the form of a terahertz wave and the control light beam has a wavelength in the visible wavelength range.

6. A method of optical imaging using metamaterials, comprising:

a) providing an imaging beam to a metamaterial array sensor comprising a plurality of unit cells made of a metamaterial and positioned adjacent to an observation object;

b) controlling a control beam provided to the unit cell to block the imaging beam incident on the unit cell; and

c) measuring a unit cell imaging beam transmission through the unit cell by measuring an imaging beam transmission of the metamaterial array sensor when the imaging beam passes through the unit cell and an imaging beam transmission of the metamaterial array sensor when the control beam is focused on the unit cell to block the imaging beam incident on the unit cell.

7. The optical imaging method of claim 6, further comprising: d) acquiring an optical analysis image of the observation object by using the unit cell imaging beam transmission amount measured according to operation c) with respect to each of the plurality of unit cells, the optical analysis image having a spatial resolution corresponding to a size of the metamaterial constituting the unit cell.

8. The optical imaging method according to claim 6, wherein the metamaterial constituting the unit cell has a size smaller than a diffraction limit of the imaging light beam.

9. The optical imaging method according to claim 6, wherein the control beam has a spot size preset to correspond to a size of the metamaterial constituting the unit cell.

10. The optical imaging method according to claim 6, wherein the imaging light beam is in the form of a terahertz wave and the control light beam has a wavelength in the visible wavelength range.

Technical Field

The present invention relates to an optical imaging apparatus using a metamaterial and an optical imaging method using a metamaterial, and more particularly, to an optical imaging apparatus using a switching metamaterial capable of overcoming a diffraction limit and adjusting transmittance of an imaging beam with respect to a single unit metamaterial in optical imaging using a metamaterial array and an optical imaging method using a switching metamaterial.

Background

The accuracy, processing accuracy and productivity of optical imaging techniques are superior to any other method. However, optical imaging techniques have reached the bottleneck of developing high resolution imaging techniques because their resolution cannot be shorter than the wavelength due to diffraction limits. As one of the methods to overcome the resolution limit due to the diffraction limit, a metamaterial having a negative refractive index has been developed, and a high resolution exceeding the diffraction limit can be obtained by introducing the metamaterial into an imaging system. Meanwhile, a metamaterial is a material (metamaterial array) in which unit cells designed with a metal or a dielectric material are arranged in a regular array, and is a new concept material having characteristics such as an ultra high refractive index and a negative refractive index that do not exist in nature.

As described above, it has been reported that an observation target can be observed by bringing the observation target into contact with a metamaterial to magnify the optical characteristics of the observation target. In particular, unlike the visible region, in the terahertz band, there are many natural resonance (rotation, vibration, intermolecular and intramolecular) frequencies of molecules, which are called unique fingerprints. By using metamaterials, the unique fingerprint can be magnified and observed even in trace amounts of molecules that were not observed in the past. When a molecule with a unique fingerprint is observed, the principle of amplifying a signal by matching the resonance frequency of a metamaterial to its frequency is used. When the observation object is in contact with the metamaterial array and the transmittance thereof is two-dimensionally scanned, the magnified optical characteristics of the observation object may be obtained as a two-dimensional image. Recently, methods for optically controlling the optical properties of metamaterials have also been investigated. For example, since the optical properties of the metamaterial are sensitive to charge density in the near-field region, the charge density can be increased by optical pumping, thereby adjusting the transmittance of light through the metamaterial.

In this regard, as the spatial resolution of the image of the observation target becomes higher, the spatial distribution of the optical characteristics of the observation target can be observed more accurately. The spatial resolution of the optical image is limited by the diffraction limit. Even in the case of two-dimensional imaging using a metamaterial array, since an imaging beam simultaneously passes through adjacent metamaterials at a level less than or equal to the diffraction limit, the spatial distribution may not be visible at the level less than or equal to the diffraction limit.

Disclosure of Invention

The present invention is directed to providing an optical imaging apparatus using a metamaterial, in which, in optical imaging using a metamaterial array, a control beam can be used to obtain a transmission amount and a transmittance of an imaging beam with respect to a single unit metamaterial, thereby acquiring an optical analysis image of an observation object having a spatial resolution of a unit metamaterial level regardless of a diffraction limit of the imaging beam; and the present invention provides an optical imaging method using the metamaterial.

The technical object of the present invention is not particularly limited to the above object, and other technical objects not described herein will also be clearly understood from the following description by those skilled in the art to which the present invention pertains.

According to an aspect of the present invention, there is provided an optical imaging apparatus using a metamaterial, the optical imaging apparatus including: a metamaterial array sensor including a plurality of unit cells made of a metamaterial and disposed adjacent to an observation object; an imaging beam providing unit that provides an imaging beam to the metamaterial array sensor; a control beam supply unit that controls a control beam supplied to the unit cell to block an imaging beam incident on the unit cell; and an imaging beam measuring unit that measures a unit cell imaging beam transmission amount through the unit cell by measuring an imaging beam transmission amount of the metamaterial array sensor when the imaging beam passes through the unit cell and an imaging beam transmission amount of the metamaterial array sensor when the control beam is focused on the unit cell to block the imaging beam incident on the unit cell.

The optical imaging apparatus may further include an image acquisition unit that acquires an optical analysis image of the observation object by using the unit cell imaging beam transmission amount measured by the imaging beam measurement unit with respect to each of the plurality of unit cells, the optical analysis image having a spatial resolution corresponding to a size of the metamaterial constituting the unit cell.

The dimensions of the metamaterial making up the unit cell may be less than the diffraction limit of the imaging beam.

The control beam may have a spot size preset to correspond to the size of the metamaterial making up the unit cell.

The imaging beam may be in the form of a terahertz wave, and the control beam may have a wavelength in the visible wavelength range.

According to another aspect of the present invention, there is provided an optical imaging method using a metamaterial, including: a) providing an imaging beam to a metamaterial array sensor comprising a plurality of unit cells made of a metamaterial and positioned adjacent to an observation object; b) controlling a control beam provided to the unit cell to block an imaging beam incident on the unit cell; and c) measuring a unit cell imaging beam transmission through the unit cell by measuring an imaging beam transmission of the metamaterial array sensor when the imaging beam passes through the unit cell and an imaging beam transmission of the metamaterial array sensor when the control beam is focused on the unit cell to block the imaging beam incident on the unit cell.

The optical imaging method may further include: d) acquiring an optical analysis image of the observation object having a spatial resolution corresponding to a size of the metamaterial constituting the unit cell by using the unit cell imaging beam transmission amount measured according to operation c) with respect to each of the plurality of unit cells.

The dimensions of the metamaterial making up the unit cell may be less than the diffraction limit of the imaging beam.

The control beam may have a spot size preset to correspond to the size of the metamaterial making up the unit cell.

The imaging beam may be in the form of a terahertz wave, and the control beam may have a wavelength in the visible wavelength range.

Drawings

Fig. 1 is a block diagram showing a schematic configuration of an optical imaging apparatus using a metamaterial according to an embodiment of the present invention.

Fig. 2 is a view visually showing imaging of an observation target with an optical imaging apparatus using a metamaterial.

FIG. 3 is a diagram illustrating an array of metamaterials as applied to an embodiment of the present invention.

Fig. 4 is a graph illustrating determination of the amount of transmission in the unit metamaterial shown in fig. 2.

Fig. 5 shows a diagram illustrating an image of an observation target acquired using the optical imaging apparatus shown in fig. 2.

Fig. 6 is a set of diagrams illustrating an example of an optical imaging apparatus using a metamaterial according to an embodiment.

Fig. 7 is a graph illustrating a change in transmittance according to one embodiment of the present invention illustrated in fig. 6.

Fig. 8 is a flowchart illustrating a procedure of an optical imaging method using a metamaterial according to another embodiment of the present invention.

Detailed Description

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In addition, the accompanying drawings are for easy understanding of the embodiments presented herein, and the technical spirit presented herein is not limited by the accompanying drawings. Thus, it should be understood that the invention is to be construed as extending to any variations, equivalents and alternatives falling within the spirit and scope of the invention. For the purpose of clearly describing the invention, portions which are not related to the specification are not shown in the drawings, the size, form and shape of each component shown in the drawings may be variously modified, and the same reference numerals refer to the same elements throughout the specification.

In addition, suffixes "module" and "unit" for components disclosed in the following description are given only or may be used interchangeably to facilitate the description of the specification, and the suffix itself does not impart any special meaning or function. In addition, in describing the embodiments presented herein, when it is judged that a detailed description of known technologies related to the present invention obscures the gist of the embodiments presented herein, a detailed description will be omitted.

Throughout the specification, in the case where one component is described as being "connected (engaged, contacted, or coupled)" to another component, such description includes the case where one component is directly "connected (engaged, contacted, or coupled)" to another component and the case where one component is indirectly "connected (engaged, contacted, or coupled)" to another component with a further component provided between one component and the other component. In addition, unless explicitly described to the contrary, the term "comprising (including or having)" will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.

The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting of the invention. Unless expressly stated otherwise, the singular forms include the plural and, unless specifically limited otherwise, the distributed and implemented components may be implemented in combination. In the present specification, the terms "comprises" or "comprising" mean that there are the features, numerals, steps, operations, elements, components, or combinations thereof described in the specification, and do not exclude the presence or addition of at least one feature, numeral, step, operation, element, component, or combinations thereof.

It will be understood that, although the terms "first and second" may be used herein to describe various components, these components should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first component could be termed a second component, and, similarly, a second component could be termed a first component, without departing from the scope of the present invention.

Fig. 1 is a block diagram showing a schematic configuration of an optical imaging apparatus using a metamaterial according to an embodiment of the present invention (hereinafter referred to as an optical imaging apparatus 100 using a metamaterial), and fig. 2 is a diagram visually showing imaging of an observation object with the optical imaging apparatus 100 using a metamaterial.

Before setting forth the detailed description, the concepts of the present invention will be briefly described. In optical imaging, when the diffraction-limited spot size of the imaging beam is larger than the size of the observation object, the detailed spatial shape of the observation object is not imaged. According to the present invention, the resolution of an image is improved by reducing the actual spot size to the level of a unit metamaterial using a metamaterial array sensor and a control beam. Here, the control beam is used to change the optical characteristics of the unit metamaterial to transmit or block the imaging beam incident on the unit metamaterial. In addition, the unit meta-material (unit cell) is made smaller than the diffraction limit of the imaging beam, and the spot size of the control beam is small enough to be incident on each unit meta-material separately. In this case, the difference between the transmission amounts of the imaging light beams generated by turning on and off the control light beam corresponds to the transmission amount of the imaging light beam passing through the unit metamaterial. When the difference between the transmission amounts according to the presence and absence of the control beam is measured in all the unit metamaterials of the array, an image having an actual resolution corresponding to the level of the unit metamaterials can be obtained.

Referring to fig. 1, an optical imaging apparatus 100 using a metamaterial includes a metamaterial array sensor 110, an imaging beam providing unit 120, a control beam providing unit 130, and an imaging beam measuring unit 140, and may further include an image acquisition unit 150.

The metamaterial array sensor 110 includes a plurality of unit cells 111 made of a metamaterial and is placed adjacent to an observation object. Referring to fig. 2, it can be confirmed that the metamaterial array sensor 110 is placed adjacent to the observation object 201.

In addition, referring to fig. 3 showing a metamaterial array applied to an embodiment of the present invention, a metamaterial applied to the metamaterial array sensor 110 may be prepared by designing a unit metamaterial having a high transmittance in a frequency band in which imaging is performed. Therefore, the optical characteristics of the observation object in contact with the metamaterial array can be sensitively observed through the near-field amplification of the metamaterial. Special metamaterials can be designed according to the properties of the observed object. In addition, in the slot antenna array, a transmission band may be determined according to the length, width, and thickness of the slot, and sensitivity may be improved according to amplification of electromagnetic waves in a near field. Accordingly, the slot antenna array has a structure suitable for application to the metamaterial array sensor according to the present invention and the optical imaging apparatus and the optical imaging method using the metamaterial including the metamaterial array sensor.

The imaging beam supply unit 120 supplies the imaging beam to the metamaterial array sensor 110. Here, the imaging beam may have the same form as the imaging beam 202 shown in fig. 2.

The control beam supply unit 130 controls the control beam supplied to the unit cell 111 to block the imaging beam incident on the unit cell 111. That is, the control beam supply unit 130 controls the control beam to be turned on or off. In this case, the control beam may have the same form as the control beam 203 shown in fig. 2.

The imaging beam may be in the form of a terahertz wave and the control beam may have a wavelength in the visible wavelength range, but the present invention is not limited thereto.

The imaging beam measurement unit 140 measures the unit cell imaging beam transmission amount through the unit cell by measuring the imaging beam transmission amount of the metamaterial array sensor 110 when the imaging beam passes through the unit cell 111 and the imaging beam transmission amount of the metamaterial array sensor 110 when the control beam is focused on the unit cell 111 to block the imaging beam incident on the unit cell 111.

Referring to fig. 4 showing that the transmission amount is determined in the unit metamaterial shown in fig. 2, by using the control beam providing unit 130, the control beam may be focused on one unit cell to switch the transmission of the imaging beam only in one unit cell. The difference between the amount of transmission turned on and off may correspond to transmission in one unit cell. In other words, in the case of the metamaterial array sensor 110, the amount of transmission increases when the control beam focused on the unit cell is turned off, and decreases when the control beam focused on the unit cell is turned on. The difference between the transmission amounts becomes the transmission amount 401 of the imaging light beam with respect to the unit cell. The amount of transmission of the metamaterial array sensor 110 when the control beam is turned on becomes the amount of transmission 402 of the imaging beam with respect to the remaining unit cells except for the unit cell.

The image acquisition unit 150 acquires an optical analysis image of the observation object, which has a spatial resolution corresponding to the size of the metamaterial constituting the unit cell 111, by using the unit cell imaging beam transmission amount measured by the imaging beam measurement unit 140 with respect to each of the plurality of unit cells 111.

Referring to fig. 5, a two-dimensional scan image of the metamaterial array sensor 110 attached to the observation target may be acquired on an x-y plane. When the transmittance in the unit metamaterial (unit cell) is repeatedly determined by performing two-dimensional scanning, an image having the size of the unit metamaterial as one pixel can be acquired, and the spatial resolution can be determined as the size of the unit metamaterial. Therefore, in the current terahertz electromagnetic wave region, there is no 1/10000-scale microscopy technology that exceeds the optical limit at present. Therefore, the present invention can be applied in the infrared and terahertz regions using a nano metamaterial array and a visible light control beam to achieve high resolution.

Meanwhile, the size of the metamaterial constituting the unit cell 111 may be smaller than the diffraction limit of the imaging beam. In addition, the control beam may have a spot size preset to correspond to the size of the metamaterial constituting the unit cell 111. Referring to fig. 2, it can be confirmed that the size of the metamaterial constituting the unit cell 111 corresponds to the diffraction limit spot size 204 of the control beam 203.

Fig. 6 is a set of diagrams showing an optical imaging apparatus 100 using a metamaterial according to an embodiment, and fig. 7 is a diagram showing a change in transmittance according to an embodiment of the present invention shown in fig. 6.

According to one embodiment of the present invention, the unit meta-material may be designed to optically switch the transmittance of the cut-off band. As a transmittance switching mechanism, there are various methods including refractive index adjustment by thermal effect and impact ionization by forming a conductive channel by photo-excitation of electric charges. As shown in fig. 6, a slot antenna array 601 manufactured on a semiconductor substrate 602 can be implemented to control transmittance in a frequency band of a terahertz wave 603 using optical excitation.

Specifically, a slot antenna array 601 made of metal fabricated on a semiconductor substrate 602 transmits terahertz waves 603 at a resonance frequency. With the control beam off as shown in fig. 6A, when the control beam is not incident on the slot antenna array 601, no charge is excited in the substrate conduction band 604 and the substrate valence band 605. However, as in the case of the control beam being on as shown in fig. 6B, when a control beam 606 having a band gap energy or more is incident on the slot antenna array 601, charges are excited in the substrate between the substrate conduction band 607 and the substrate valence band 608, and the transmission of terahertz waves is blocked by the excited charges.

As shown in fig. 6, when the transmittance is measured with respect to a slot antenna array manufactured on a semiconductor substrate using terahertz waves as an imaging beam, the wavelength of the control beam may be selected so that the energy of the control beam is greater than or equal to the band gap energy of the substrate. When the control beam is turned off, a terahertz wave corresponding to the resonance frequency of the slit is transmitted. On the other hand, when the control beam is turned on, the control beam excites charges in the substrate, thereby blocking transmission of the terahertz wave. When the transmittance difference is analyzed by turning the control beam on and off, as shown in fig. 7, the transmittance of the imaging beam with respect to the corresponding single unit metamaterial can be obtained.

As described above, the present invention can be suitable for imaging using a long wavelength greater than or equal to a terahertz wave. When using a control beam in the visible region and a nano-metamaterial, a resolution at least several hundred times smaller than the wavelength can be obtained. In addition, the present invention can be easily combined and used with terahertz time-domain spectroscopy. When imaging biological materials using long wavelengths greater than or equal to terahertz waves, low spatial resolution (which makes it difficult to distinguish biological structures) has limitations. Thus, by facilitating imaging of long wavelength biological materials, the present invention can be used in fields such as medicine.

Fig. 8 is a flowchart illustrating a procedure of an optical imaging method using a metamaterial according to another embodiment of the present invention. The optical imaging method using a metamaterial according to the present embodiment corresponds to an optical imaging method using the optical imaging apparatus 100 using a metamaterial (the optical imaging apparatus 100 has been described with reference to fig. 1 to 7). Therefore, hereinafter, the same contents as those described above will be omitted, and all the following processes represent functions performed by the optical imaging apparatus 100 using a metamaterial.

The optical imaging method using a metamaterial according to the present embodiment provides an optical imaging method using a metamaterial, including: a) providing an imaging beam to a metamaterial array sensor including a plurality of unit cells made of a metamaterial and placed adjacent to an observation object (S110); b) controlling a control beam supplied to the unit cell to block an imaging beam incident on the unit cell (S120); and c) measuring a unit cell imaging beam transmission amount through the unit cell by measuring an imaging beam transmission amount of the metamaterial array sensor when the imaging beam passes through the unit cell and an imaging beam transmission amount of the metamaterial array sensor when the control beam is focused on the unit cell to block the imaging beam incident on the unit cell (S130).

In this embodiment, the optical imaging method may further include: d) acquiring an optical analysis image of the observation object having a spatial resolution corresponding to the size of the metamaterial constituting the unit cell by using the unit cell imaging beam transmission amount measured according to operation c) with respect to each of the plurality of unit cells (S140).

In this embodiment, the dimensions of the metamaterial making up the unit cell may be less than the diffraction limit of the imaging beam.

In the present embodiment, the control beam may have a preset spot size preset to correspond to the size of the metamaterial constituting the unit cell.

In this embodiment, the imaging beam may be in the form of a terahertz wave, and the control beam may have a wavelength in the visible wavelength range.

As described above, the present invention relates to a method of achieving ultra-high resolution imaging using a metamaterial array sensor. In the present invention, by bringing a metamaterial array sensor and an observation target into contact with each other and using an imaging beam for measuring the transmittance thereof together with a control beam for individually switching the transmittance of the imaging beam in a unit metamaterial, an image is acquired by two-dimensionally scanning the difference between the transmittance amounts of the imaging beam generated when the unit metamaterial is switched. Since the acquired image has a spatial resolution as large as the size of the unit metamaterial regardless of the diffraction limit of the imaging beam, ultra-high resolution imaging can be achieved by using a metamaterial array having the size of the unit metamaterial smaller than the diffraction limit.

According to an embodiment of the present invention, a control beam capable of switching the transmittance of an imaging beam is focused on one unit metamaterial. The difference between the intensities of the transmitted imaging beams produced by turning the control beam on and off corresponds to the intensity of the imaging beam passing through the respective unit metamaterial. When the same measurement is made for all the unit metamaterials in the metamaterial array, an image with a spatial resolution as large as the size of the unit metamaterials will be obtained regardless of the diffraction limit of the imaging beam in the array area.

According to the present invention, in optical imaging, the transmission amount and transmittance of an imaging beam with respect to a single unit metamaterial can be obtained, and an optical analysis image in which the spatial resolution of imaging is improved to the level of the size of the unit metamaterial can be obtained regardless of the diffraction limit.

In addition, according to the present invention, in imaging using a long wavelength greater than or equal to a terahertz wave, when a control beam and a nano metamaterial in a visible light region are used, a resolution at least several hundred times smaller than the wavelength can be obtained. Furthermore, the present invention can be easily combined and used with terahertz time-domain spectroscopy. When a biological material is imaged using a long wavelength greater than or equal to a terahertz wave, the problem of occurrence of low spatial resolution (which makes it difficult to distinguish biological structures) can be solved. Thus, by facilitating imaging of long wavelength biological materials, the present invention can be used in fields such as medicine.

It is to be understood that the effects of the present invention are not particularly limited to the above-described effects, and the present invention includes all effects that can be derived from the configuration of the present invention described in the detailed description of the present invention or the claims.