Transparent ultrasonic sensor and method for manufacturing the same

Abstract

The present invention relates to a transparent ultrasonic sensor, which may include: an integration part that performs optical impedance matching and is made of a transparent material; a piezoelectric layer located behind the integration part and made of a transparent material; a first electrode layer and a second electrode layer respectively located behind and in front of the piezoelectric layer and respectively made of a transparent conductive substance; a first housing connected to the first electrode layer; and a second housing connected to the second electrode layer.

Description

Technical Field

[0001] The present invention relates to an ultrasonic sensor and a manufacturing method thereof, and more particularly, to a transparent ultrasonic sensor that enables light transmission and a manufacturing method thereof. Background Art

[0002] An ultrasonic sensor or transducer is a sensor that can measure the physical distance to an object and obtain an image of the object by using the following principle: converting electrical energy into acoustic energy by using the characteristics of a piezoelectric material, then transmitting this energy to an object as a target, and converting the reflected acoustic energy back into an electrical signal.

[0003] Recently, in order to perform high-precision sensing operations, obtain high-resolution images, and enhance user convenience, technologies that integrate optical devices such as optical cameras and lasers with ultrasonic sensors have been actively developed.

[0004] However, since existing ultrasonic sensors are opaque, they cannot be integrated with optical devices that require a transparent medium, and it is impossible to align the irradiated laser and the ultrasonic sensor on the same axis. Summary of the Invention

[0005] Technical Problem

[0006] The technical problem to be solved by the present invention is to make light transmit through the entire ultrasonic sensor, thereby simplifying the structure of the optical system that utilizes the ultrasonic sensor.

[0007] Another technical problem to be solved by the present invention is to adjust the foci of the light and the ultrasonic signal that are incident on the transparent ultrasonic sensor, reflected, and then incident again, thereby improving the clarity of the ultrasonic image detected by the ultrasonic sensor and the clarity of the optical signal.

[0008] Technical Solution

[0009] A transparent ultrasonic sensor according to one feature of the present invention for solving the above technical problem includes: an integration part that performs optical impedance matching and is made of a transparent material; a piezoelectric layer that is located behind the integration part and is made of a transparent material; a first electrode layer and a second electrode layer that are respectively located behind and in front of the piezoelectric layer and are respectively made of a transparent conductive substance; a first housing that is connected to the first electrode layer; and a second housing that is connected to the second electrode layer.

[0010] The integration part may be provided with an acoustic lens.

[0011] The acoustic lens may have a concave shape or a convex shape.

[0012] The integration part may include at least one of transparent glass, transparent epoxy resin, and transparent silicone grease.

[0013] The piezoelectric layer may include at least one of LNO, PMN-PT, PVDF, and PVDF-TrFE.

[0014] Each of the first electrode layer and the second electrode layer may include at least one of silver nanowires, ITO, carbon nanotubes, and graphene.

[0015] The sizes of the first electrode layer and the second electrode layer may be different from each other.

[0016] Each of the first housing and the second housing may be configured in an annular shape having an empty space in the middle.

[0017] The first housing may be arranged in contact with the edge portion of the first electrode layer, and the second housing may be arranged in contact with the edge portion of the second electrode layer.

[0018] The piezoelectric layer, the first electrode layer, and the first housing may be arranged in the internal space of the second housing.

[0019] The first housing and the second housing may include a conductive material.

[0020] The transparent ultrasonic sensor according to the above characteristics may further include: a first signal line connected to the first housing; and a second signal line connected to the second housing.

[0021] The transparent ultrasonic sensor according to the above characteristics may further include: a rear layer arranged in contact with the first electrode layer and attenuating ultrasonic signals.

[0022] The rear layer may be surrounded by the first housing.

[0023] The rear layer may include a transparent glass type or a transparent epoxy resin type.

[0024] The transparent ultrasonic sensor according to the above characteristics may further include: an insulating portion located between the first housing and the second housing and made of a transparent insulating material.

[0025] The transparent ultrasonic sensor according to the above characteristics may further include: a protective layer located before the integration portion and performing acoustic impedance matching.

[0026] The protective layer may include parylene.

[0027] The transparent ultrasonic sensor according to the above characteristics may further include: a correction lens located after the integration portion, adjusting the focus of light passing through the integration portion, and made of a transparent material.

[0028] The correction lens may have a convex shape.

[0029] A method of manufacturing a transparent ultrasonic lens according to another feature of the present invention may include the following steps: disposing a piezoelectric layer on a substrate; forming a transparent first electrode layer on an exposed first surface of the piezoelectric layer; attaching and disposing a first housing at an edge portion of the first electrode layer; forming a transparent rear layer on the first surface of the first electrode layer where the first housing is not disposed; attaching and disposing a second housing at an edge portion of the substrate in a spaced-apart manner from the first housing; injecting a transparent insulating material between the first housing and the second housing to form an insulating portion, thereby forming a first preliminary transparent ultrasonic sensor; rotating the first preliminary transparent ultrasonic sensor located above the substrate 180 degrees in the vertical direction and disposing it on the substrate; forming a transparent second electrode layer on an exposed second surface of the piezoelectric layer, a surface of the insulating portion, and a surface of the second housing; forming a transparent integration portion on the second electrode layer; and forming a transparent protective layer on the integration portion on the exposed first electrode layer.

[0030] The method of manufacturing a transparent ultrasonic lens according to the feature may further include the following steps: flipping the transparent ultrasonic sensor formed up to the protective layer 180 degrees in the vertical direction and disposing it on the substrate; and forming a correction lens on the exposed rear layer.

[0031] The method of manufacturing a transparent ultrasonic lens according to the feature may further include the following steps: flipping the transparent ultrasonic sensor formed up to the protective layer 180 degrees in the vertical direction and disposing it on the substrate; and connecting a first signal line to the first housing and connecting a second signal line to the second housing.

[0032] Technical effects

[0033] According to this feature, since all components present in the effective region of the transparent ultrasonic sensor are made of a transparent material that transmits light, the degree of freedom in arranging an optical system equipped with the transparent ultrasonic sensor is increased, and thus, effective utilization of space can be achieved.

[0034] Moreover, since the integration portion adjusts the focus of ultrasonic signals and light, the clarity of an image obtained from a signal output from the transparent ultrasonic sensor is greatly improved. Thus, it is possible to clearly determine whether a certain object exists in the obtained image and the shape of the object.

[0035] In addition, since the focus of light is further adjusted by the correction lens, the clarity of the image output from the transparent ultrasonic sensor is further increased.

[0036] Since the first signal line and the second signal line for inputting and outputting external signals are connected to the first housing and the second housing arranged so as to surround the edge portion of the transparent ultrasonic sensor, the first signal line and the second signal line can be freely connected without reducing the effective area.

[0037] In addition, the optical element can be freely coupled to the outermost second housing without reducing the effective area. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figures 1a to 1d is a conceptual diagram showing various arrangement relationships between a transparent ultrasonic sensor and an optical module according to an embodiment of the present invention.

[0039] Figure 2a and Figure 2b is an image of a transparent ultrasonic sensor manufactured according to an embodiment of the present invention, Figure 2a is an image in the case where a plano-convex correction lens is attached, Figure 2b is a back image of the transparent ultrasonic sensor in which the correction lens and the acoustic lens are omitted.

[0040] Figure 3 is a conceptual cross-sectional view obtained by cutting the transparent ultrasonic sensor in one direction according to an embodiment of the present invention, showing the case where the correction lens is a plano-convex correction lens having a convex shape as an example.

[0041] Figure 4 is a conceptual exploded perspective view of the transparent ultrasonic sensor according to an embodiment of the present invention. As an example, it shows the case where the correction lens is a plano-convex correction lens having a convex shape.

[0042] Figure 5a and Figure 5b are examples schematically showing the optical paths when a plano-concave acoustic lens having a plano-concave shape and a plano-convex acoustic lens having a plano-convex shape are used in the transparent ultrasonic sensor according to an embodiment of the present invention, respectively.

[0043] Figure 6a and Figure 6b are examples schematically showing the optical paths when the correction lens is not used and when the correction lens is used in the transparent ultrasonic sensor according to an embodiment of the present invention, respectively.

[0044] Figures 7a to 7k is a diagram showing a manufacturing method of a transparent ultrasonic sensor according to an embodiment of the present invention.

[0045] REFERENCE MARK DESCRIPTION

[0046] 1: Transparent ultrasonic sensor

[0047] 11: Protective layer

[0048] 13: Integration section

[0049] 15: Piezoelectric section

[0050] 151: Piezoelectric layer

[0051] 153: First electrode layer

[0052] 155: Second electrode layer

[0053] 16: Rear layer

[0054] 171: First housing

[0055] 173: Second housing

[0056] 18: Insulation section

[0057] 19: Correction lens Detailed implementation manners

[0058] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the process of describing the present invention, in cases where it is judged that a detailed description of publicly known techniques or configurations in the art may make the gist of the present invention unclear, a part of it is omitted in the detailed description. Also, the terms used in this specification are terms used to appropriately represent the embodiments of the present invention, and they may be changed according to those skilled in the art or conventions, etc. Therefore, the definition of these terms should be based on the entire content of this specification.

[0059] The terms used herein are only for referring to specific embodiments and are not intended to limit the present invention. Unless the context clearly dictates otherwise, the singular forms used herein are also intended to include the plural forms. The meaning of "including" used in the specification is to specify specific features, regions, integers, steps, operations, elements, and / or components, and does not exclude the existence or addition of other specific features, regions, integers, steps, operations, elements, components, and / or groups.

[0060] Hereinafter, a transparent ultrasonic sensor and a manufacturing method thereof according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0061] First, with reference to Figures 1a to 1d , the operating concept of a transparent ultrasonic sensor 1 according to an embodiment of the present invention will be described.

[0062] Figures 1a to 1d A schematic structure of an optical system using the transparent ultrasonic sensor 1 is shown.

[0063] As Figures 1a to 1dAs shown, the optical module 100 for irradiating light places the transparent ultrasonic sensor 1 in front of it, and there is an object 200 behind which reflects the light irradiated through the transparent ultrasonic sensor 1 and reflects it back towards the transparent ultrasonic sensor 1 side.

[0064] The optical module 100 is used to irradiate light towards the transparent ultrasonic sensor 1 side and can be a camera, a laser irradiation unit, or the like.

[0065] The transparent ultrasonic sensor 1 uses the light output from the optical module 100 and the electrical signal applied to the transparent ultrasonic sensor 1 to generate ultrasonic waves, irradiates them towards the object 200, and outputs again the electrical signal corresponding to the ultrasonic waves reflected by the object 200 and incident thereon, thereby being able to obtain an ultrasonic image of the object 200.

[0066] This kind of transparent ultrasonic sensor 1 uses the piezoelectric effect and the inverse piezoelectric effect to send ultrasonic waves towards the object 200 side and receives the ultrasonic waves reflected from the object 200 to generate a corresponding electrical signal.

[0067] At this time, the piezoelectric effect can be the effect of generating electricity by causing dielectric polarization when a mechanical force is applied to a piezoelectric material. On the contrary, the inverse piezoelectric effect can be the phenomenon of contraction and relaxation when an electric current is applied.

[0068] An object 200 such as a part of the human body reflects the ultrasonic waves applied from the transparent ultrasonic sensor 1 to the transparent ultrasonic sensor 1 side, thereby being able to obtain an ultrasonic image of the corresponding part of the reflected ultrasonic wave signal.

[0069] In Figures 1a to 1d diverse arrangement structures of the transparent ultrasonic sensor 1 located between the optical module 100 and the object 200 are shown.

[0070] Figure 1a This is the case where the transparent ultrasonic sensor 1 is arranged in such a way that the path of the light output from the optical module 100 and the path of the ultrasonic wave signal output from the transparent ultrasonic sensor 1 are parallel to each other. That is, the light emitting surface S1 of the optical module 100 and the incident surface S2 of the transparent ultrasonic sensor 1 adjacent to the light emitting surface S1 are arranged in a parallel state.

[0071] Therefore, in Figure 1a this case, the path P1 of the light finally incident on the object 200 and the ultrasonic wave signal path P2 of the transparent ultrasonic sensor 1 can be the same or parallel to each other, so the angle formed by the two paths P1 and P2 can be 0 degrees.

[0072] As described above, since the optical module 100 is located behind the transparent ultrasonic sensor 1 or on the same path as the path P2 of the transparent ultrasonic sensor 1, an image of the object 200 located in front of the transparent ultrasonic sensor 1 can be obtained. In this case, signals at the same position of the same object 200 can be obtained without distortion of the signals or light output from the transparent ultrasonic sensor 1 and the optical module 100, so that a correct image can be obtained.

[0073] Figures 1b to 1d This is the case where the transparent ultrasonic sensor 1 is arranged between the optical module 100 and the object 200 in such a way that the path P1 of the light output from the optical module 100 and the path P2 of the ultrasonic signal output from the transparent ultrasonic sensor 1 form a predetermined angle θ1 greater than 0 degrees.

[0074] Figure 1b This is the case where the angle θ1 formed by the two paths P1 and P2 is greater than 0 and less than 90 degrees. Figure 1c This is the case where the angle θ1 formed by the two paths P1 and P2 is 90 degrees. Figure 1d This is the case where it is greater than 90 degrees.

[0075] As Figure 1b shown, when the angle θ1 formed by the two paths P1 and P2 is greater than 0 and less than 90 degrees, the transparent ultrasonic sensor 1 is arranged obliquely between the optical module 100 and the object 200. That is, the incident surface S2 of the transparent ultrasonic sensor 1 is arranged obliquely with respect to the light emitting surface S1 of the optical module 100.

[0076] In Figure 1b the position of the transparent ultrasonic sensor 1 is arranged slightly (i.e., less than 90 degrees) obliquely with respect to the optical module 100, but conversely, the position of the optical module 100 can be arranged obliquely with respect to the transparent ultrasonic sensor 1 at an angle less than 90 degrees.

[0077] In Figure 1c since the incident surface S2 of the transparent ultrasonic sensor 1 forms 90 degrees with respect to the light emitting surface S1 of the optical module 100 when the angle θ1 formed by the two paths P1 and P2 is 90 degrees, it is necessary to change the path P1 of the light output from the optical module 100 to the side of the transparent ultrasonic sensor 1. Therefore, as Figure 1c shown, when the optical module 100 and the transparent ultrasonic sensor 1 are arranged, a reflector that reflects the light output from the optical module 100 to the transparent ultrasonic sensor 1 can be arranged. At this time, the reflector can be constituted by a prism, a mirror, or the like. In Figure 1c this case, the path P1a of the light finally incident on the object 200 can be as Figure 1aIt is also consistent with the ultrasonic signal path P2 of the transparent ultrasonic sensor 1.

[0078] By means of Figure 1c this arrangement, not only can an image of the object 200 facing the optical module 100 (i.e., Figure 1a the object 200) be obtained, but also an image of an object that detaches from the front of the optical module 100 and is located on the side or the like can be obtained.

[0079] Moreover, in Figure 1d the case of Figure 1c it is the same as Figure 1d the case of Figure 1b it is the same. There can be a reflector 400 for changing the optical path P1 of the optical module 100 toward the transparent ultrasonic sensor 1 side. In

[0080] As described above, since the transparent ultrasonic sensor 1 is transparent, the transparent ultrasonic sensor 1 can be arranged in various structures between the optical module 100 and the object 200, thereby improving the design diversity of the optical system equipped with the transparent ultrasonic sensor 1.

[0081] Furthermore, since the arrangement of the transparent ultrasonic sensor 1 varies diversely according to the arrangement space of the optical system equipped with the transparent ultrasonic sensor 1, the degree of freedom in setting the optical system is also increased.

[0082] In Figures 1a to 1d the case of

[0083] it is possible to adjust the distance between the optical module 100 and the transparent ultrasonic sensor 1. Since the distance between the object 200 for which a signal is to be obtained and the transparent ultrasonic sensor 1 varies depending on the field of use, by adjusting the distance between the optical module 100 and the transparent ultrasonic sensor 1, a signal can be obtained at an accurate position.

[0084] Moreover, in the case of the optical module 100, taking a camera as an example, a very diverse range of cameras can be applied, from a very small size used for a blood vessel catheter or endoscope as a medical device to a relatively large size used for an automobile.

[0085] Next, referring to Figure 2a 、 Figure 2b and Figure 6a, Figure 6b This embodiment of the transparent ultrasonic sensor 1 will be described.

[0086] As Figure 2a and Figure 2b shown, the transparent ultrasonic sensor 1 according to an embodiment of the present invention has a circular shape with a circular planar shape, but is not limited thereto.

[0087] As Figures 2a to 4 shown, the transparent ultrasonic sensor 1 according to an embodiment of the present invention may include a protective layer 11 starting from the right side, an integration part 13 located behind the protective layer 11, a piezoelectric part 15 located behind the integration part 13, a first housing 171 and a second housing 173 connected to the piezoelectric part 15, a rear layer 16 located behind the piezoelectric part 15, an insulating part 18 located between the first housing 171 and the second housing 173, and a calibration lens part 19 located behind the second housing 173.

[0088] The protective layer 11 is used to physically and electrically protect the transparent ultrasonic sensor 1 and reduce the difference in acoustic impedance with the medium (i.e., the object 200) to which the ultrasonic signal is to be irradiated. Therefore, the protective layer 11 has a protection function and can operate as an integration layer for implementing acoustic impedance matching between a liquid (e.g., water) and a living body.

[0089] Such a protective layer 11 can be made of a transparent material. As an example, the protective layer 11 may include parylene, which is a transparent polymer.

[0090] In this example, the acoustic impedance of the protective layer 11 may be about 2.84 Mrayls.

[0091] As Figure 3 and Figure 4 shown, such a protective layer 11 may be located in front of and on the side of the piezoelectric part 15 and on the side of the second housing 173 at the outermost edge of the transparent ultrasonic sensor 1.

[0092] Therefore, the protective layer 11 can ultimately form the front and side surfaces of the transparent ultrasonic sensor 1.

[0093] The integration part 13 located behind the protective layer 11 is used to reduce the difference in acoustic impedance with the medium (i.e., the object 200) to which the ultrasonic signal generated from the piezoelectric part 15 is to be irradiated.

[0094] That is, when an ultrasonic signal is generated by the operation of the piezoelectric unit 15, in order to effectively transmit the ultrasonic signal in water, biological tissue, or other media that are not air, it is necessary to maximize the adjustment of the acoustic impedance of the corresponding medium to minimize the loss of ultrasonic energy.

[0095] Each acoustic lens of the integration unit 13 in this example can be of a focused type that utilizes an acoustic lens capable of adjusting the focal points of light and ultrasonic signals.

[0096] As described above, since the integration unit 13 has a focal point adjustment function, the ultrasonic signal reflected by the object 200 and incident on the transparent ultrasonic sensor 1 is accurately formed at the desired position of the piezoelectric unit 15.

[0097] Therefore, by means of this focal point adjustment function of the integration unit 13, the focal point of the ultrasonic image obtained from the ultrasonic signal output from the piezoelectric unit 15 can be adjusted, enabling a clear ultrasonic image to be obtained.

[0098] Thus, the clarity of the image obtained by the operation of the transparent ultrasonic sensor 1 is improved, enabling a clear image of the desired part of the object 200 irradiated with the ultrasonic signal to be obtained.

[0099] Moreover, since the integration unit 13 utilizes acoustic lenses, the curvature of the surface is constant, and the transparency of the surface is improved. Thus, when transmitting and receiving ultrasonic signals irradiated to or reflected from the object 200, the loss amount of the ultrasonic signals can be reduced.

[0100] Also, an additional transmission film or blocking film can be formed on the integration unit 13 as needed to transmit or block only signals in a desired wavelength band.

[0101] The acoustic lenses provided in the integration unit 13 can be made of at least one of transparent glass materials, transparent epoxy resin materials, and transparent silicone grease materials.

[0102] Such acoustic lenses can be selected according to the functions of the acoustic lenses.

[0103] For example, when the acoustic lens functions as an integration layer for implementing the integration function of acoustic impedance, in the case where the piezoelectric material provided in the piezoelectric unit 15 is not in the form of a polymer such as PVDF or PVDF-TrFE, the acoustic lens is more preferably made of glass materials.

[0104] That is, when the piezoelectric material is made of lithium niobite (LNO) or PMN-PT, the acoustic impedance is 30 to 40 Mrayls, which is relatively high. However, in the case of glass, the acoustic impedance is 10 to 15 Mrayls, which is relatively low. Thus, it has an acoustic impedance value that is easy to match the acoustic impedance, and the transparency is very good. Therefore, when the piezoelectric material is not in the form of a polymer, a sound lens can be made of glass.

[0105] However, when the integration layer that performs the integration function of the acoustic impedance has been manufactured, the sound lens can be made of a transparent epoxy resin or a transparent silicone grease.

[0106] That is, if there is already an integration layer (about 7 to 20 Mrayls) for performing the integration function between the piezoelectric material with an acoustic impedance of about 30 to 40 Mrayls and the biological tissue or water (i.e., the medium to which ultrasonic waves are to be irradiated) with an acoustic impedance of about 1 to 2 Mrayls, then no separate acoustic impedance matching operation is required, and epoxy resins or silicone greases (about 1 to 3 Mrayls) with an acoustic impedance similar to that of biological tissue or water are suitable. That is, since the acoustic impedance of epoxy resins and silicone greases is almost similar to that of biological tissue or water, no separate acoustic impedance matching is required.

[0107] Moreover, the curvature of the surface of the sound lens and whether the sound lens is concave or convex can be determined by considering the speed of sound and the speed of sound of the material of the sound lens.

[0108] For example, when the sound lens is made of glass, an optical lens can be used. At this time, since the speed of light in glass is faster than that in water, the sound lens can be designed in a concave shape such as a plano-concave shape (e.g., Figure 5a ).

[0109] When the sound lens is made of a transparent epoxy resin, a polishing process needs to be performed on the initially manufactured sound lens to maximize transparency, thereby finally completing the sound lens. Thus, even when the sound lens is made of an epoxy resin, since the speed of light in the epoxy resin is faster than that in water, the sound lens can also be made in a plano-concave shape.

[0110] When the sound lens is made of a transparent silicone grease, as in the case of epoxy resins, a separate polishing process also needs to be performed to maximize the transparency of the completed sound lens. In this case, since the speed of light in the silicone grease is slower than that in water, different from the cases of glass and epoxy resins, the sound lens can be made in a convex shape such as a plano-convex shape (e.g., Figure 5b) Thus, in the case where the acoustic lens is manufactured in a plano-convex shape, the acoustic lens can have a function of collecting light.

[0111] As Figure 3 and Figure 4 shown, the piezoelectric unit 15 may include a piezoelectric layer 151, and a first electrode layer 153 and a second electrode layer 155 respectively located behind and in front of the piezoelectric layer 151.

[0112] The piezoelectric layer 151 is a layer that generates the piezoelectric effect and the inverse piezoelectric effect. As described above, the piezoelectric layer 151 may contain a piezoelectric material of at least one of LNO (lithium niobite), PMN-PT, PVDF, and PVDF-TrFE.

[0113] The electromechanical coupling coefficient of LNO is about 0.49 and is very high, so the electromechanical energy conversion efficiency is very good.

[0114] Moreover, since the dielectric permittivity of LNO is low, when the piezoelectric layer 151 is made of LNO, the transparent ultrasonic sensor can be suitable for a large aperture single element transducer.

[0115] In addition, since the Curie temperature of LNO is high, it can well withstand high temperatures, so that a transparent ultrasonic sensor 1 with good heat resistance can be developed.

[0116] In addition, when the piezoelectric layer 151 is made of LNO, a single element ultrasonic sensor with a center frequency of 10 MHz to 400 MHz can be easily developed.

[0117] When the piezoelectric layer 151 contains PMN-PT, since the piezoelectric performance (d33~1500 - 2800 pC / N) and the electromechanical coupling coefficient (k>0.9) of PMN-PT are very high, the performance of the transparent ultrasonic sensor 1 can be improved.

[0118] This PMN-PT is different from LNO and has a high dielectric permittivity, so a transparent ultrasonic sensor 1 suitable for a small aperture single or array ultrasonic transducer can be developed.

[0119] Moreover, when the piezoelectric layer 151 contains at least one of PVDF and PVDF-TrFE, it may have the following characteristics.

[0120] PVDF and PVDF-TrFE have the form of a polymer film, and a flexible and stretchable piezoelectric layer 151 can be fabricated. Thereby, the thickness of the piezoelectric layer 151 can be reduced, and a transparent ultrasonic sensor 1 for signals in a high-frequency band of about 100 MHz can be fabricated corresponding to the reduced thickness.

[0121] Moreover, PVDF and PVDF-TrFE have a low electromechanical coupling coefficient and a high receiving constant, and have a wider bandwidth compared to other piezoelectric materials. Elements in the form of a single element or an array can be easily fabricated.

[0122] Herein, a single element (e.g., a single ultrasonic transducer) may refer to an ultrasonic transducer in which the number of all components including the piezoelectric material is one. And an element in the form of an array (e.g., an array ultrasonic transducer) may be an ultrasonic transducer in which the number of all components including the piezoelectric material is multiple (n), and can generally be configured in a form mainly used in hospitals. At this time, the form may be a linear form, a convex form, a two-dimensional (2D) matrix, etc.

[0123] In the case of this example, a small-diameter single or array ultrasonic transducer can be fabricated similarly to PMN-PT.

[0124] The material characteristics of such a piezoelectric layer 151 can be summarized as in the following [Table 1].

[0125] [Table 1]

[0126] LNO PMN-PT PVDF & PVDF-TrFE Size Large Small Medium Bandwidth size Medium Medium Wide Available frequency range 1 MHz to 400 MHz 1 MHz to 100 MHz 1 kHz to 100 MHz Signal transmission performance Good Good Poor Signal reception performance Good Good Good Electromechanical coupling coefficient Medium Good Poor

[0127] The first electrode layer 153 and the second electrode layer 155 respectively located in front of and behind the piezoelectric layer 151 receive a (+) drive signal and a (-) drive signal from a drive signal generator (not shown), respectively, and exert an inverse piezoelectric effect on the piezoelectric layer 151, so that an ultrasonic signal is transmitted toward the object 200 side. On the contrary, an electric signal generated by receiving the piezoelectric effect of the piezoelectric layer 151 caused by the ultrasonic signal reflected by the object 200 is received and output to the outside. As described above, such a first electrode layer 153 and a second electrode layer 155 can be formed of a transparent conductive material. For example, it may include at least one of silver nanowires (AgNW), ITO, carbon nanotubes, and graphene.

[0128] As Figure 3 shown, in order to be easily combined with the first housing 171 and the second housing 173, the sizes of the first electrode layer 153 and the second electrode layer 155 may be different from each other.

[0129] Therefore, as Figure 3 shown, in the first electrode layer 153 and the second electrode layer 155 having a circular planar shape, the diameter of the second electrode layer 155 may be different from the diameter of the first electrode layer 153, such that a part (e.g., an edge portion) of the second electrode layer 155 may extend outward from the edge portion of the first electrode layer 153.

[0130] When an electrical signal (e.g., a pulse signal) is applied to the piezoelectric material, the piezoelectric material (i.e., the piezoelectric layer 151) vibrates back and forth to generate an ultrasonic signal, generating an ultrasonic signal not only in front of the piezoelectric layer 151 facing the object 200, but also behind the piezoelectric layer 151 opposite to the front surface.

[0131] At this time, since the ultrasonic signal generated behind does not face the object 200, the ultrasonic signal generated behind is used as a noise signal. And a part of the ultrasonic signal reflected by the object 200 and returned may be output to the correction lens unit 19 side through the integration unit 13.

[0132] Therefore, the rear layer 16 may be located behind the piezoelectric unit 15, thereby performing the function of attenuating the ultrasonic signal generated behind the piezoelectric unit 15 and attenuating the ultrasonic signal reflected by the object 200.

[0133] Thus, since the rear layer 16 is located behind the piezoelectric unit 15 (i.e., on the surface opposite to the front surface of the piezoelectric unit 15 where the reflected ultrasonic signal is incident), the incident ultrasonic signal does not pass through the rear of the piezoelectric unit 15.

[0134] Thereby, it is possible to prevent unnecessary signal interference caused by the ultrasonic signal passing through the rear of the piezoelectric unit 15 and prevent loss of the ultrasonic signal reflected to the piezoelectric unit 15, thereby reducing the ring down signal, and further reducing the ring down phenomenon.

[0135] Ring down is a phenomenon in which unnecessary signals extend for a long time on the time axis and is a factor that has an adverse effect on image generation.

[0136] Therefore, in order to reduce such a ring down phenomenon through the rear layer 16, at least one of the acoustic impedance and the thickness may be adjusted to manufacture a suitable rear layer 16.

[0137] When the back layer 16 is made of a material with a relatively high acoustic impedance, the halo phenomenon is reduced, and the reduction of the halo phenomenon on the time axis is similar in meaning to the broadening of the bandwidth in the frequency domain. However, conversely, when transmitting and receiving ultrasonic signals, the magnitude of the entire ultrasonic signal can also be attenuated by the back layer 16.

[0138] Conversely, when the back layer 16 is made of a material with a relatively low acoustic impedance, although the bandwidth is reduced without significantly reducing the halo phenomenon, the amount of ultrasonic signal transmitted and received can be increased.

[0139] The back layer 16 can also be made of a transparent non-conductive material. For example, it can be made of a transparent epoxy resin (e.g., Epotek301) or transparent glass.

[0140] When the back layer 16 is made of Epotek301, in the case of an acoustic impedance of 3.1 Mrayls and a relatively low acoustic impedance, low signal damping is achieved, so that the transparent ultrasonic sensor 1 can obtain a higher signal.

[0141] Moreover, Epotek301 has very high transparency. For example, it has a transparency of about 95% or more at wavelengths from 380 nm to 2000 nm, and since it is cured at room temperature, it is easy to manufacture the back layer 16.

[0142] When the back layer 16 is made of glass, the transparency and flatness are high, and no separate curing process is required.

[0143] In the case where the glass has an acoustic impedance of about 13 Mrayls, the pulse length is reduced due to the high signal attenuation effect of the back layer 16, so that the halo effect is reduced, but it can achieve the effect of increasing the bandwidth of the frequency of the transparent ultrasonic sensor 1.

[0144] This back layer 16 can be omitted as needed.

[0145] As described above, the first housing 171 and the second housing 173 are respectively connected to the first electrode layer 153 and the second electrode layer 155. Therefore, the first housing 171 and the second housing 173 can be made of a transparent conductive material containing a conductive material (e.g., copper) that realizes the transmission of electrical signals.

[0146] Therefore, as Figure 3 shown, the first housing 171 can receive the corresponding signal through the first signal line L1 and transmit it to the first electrode layer 153. Conversely, the signal applied by the first electrode layer 153 can be output to the first signal line L1.

[0147] The second housing 173 can also receive a corresponding signal through a second signal line L2 that is a different signal line from the first signal line L1 and transfer it to the second electrode layer 155. Conversely, the signal applied by the second electrode layer 155 can be output to the second signal line L2.

[0148] In this example, the signal input to the first signal line L1 can be a pulse signal, and the signal introduced into the second signal line L2 can be a ground signal or a shielding signal (-). Therefore, the first housing 171 can transfer the pulse signal to the first electrode layer 153, and the second housing 173 can transfer the ground signal to the second electrode layer 155.

[0149] As Figure 4 shown, the first housing 171 and the second housing 173 have a ring shape and can be arranged in contact with the edge portions (i.e., the circular side surfaces) of the corresponding electrode layers 153 and 155 that are in contact with each other.

[0150] That is, the first electrode layer 153 and the second electrode layer 155 can be inserted and installed into the empty space located inside the first housing 171 and the second housing 173.

[0151] Therefore, as Figure 2a and Figure 2b shown, the first housing 171 and the second housing 173 can be arranged to surround the periphery of the actual effective area AR1 of the transparent ultrasonic sensor 1, thereby minimizing the reduction of the effective area AR1 caused by the first housing 171 and the second housing 173 (substantially the first housing 171).

[0152] As described above, since the first housing 171 and the second housing 173 function to transfer electrical signals to the corresponding electrode layers 153 and 155, the first housing 171 and the second housing 173 can contain substances with good conductivity.

[0153] Since the first housing 171 is located at the edge portion (i.e., the peripheral portion) of the first electrode layer 153 that is arranged behind the entire piezoelectric layer 151 that receives light, the first housing 171 preferably has as thin a width W11 as possible and can have as thick a thickness as possible to minimize the signal loss rate caused by wiring resistance and the like.

[0154] As Figure 3 and Figure 4 shown, the second housing 173 is combined with the second electrode layer 155 that has a larger diameter than the first electrode layer 153, and thus has a larger diameter than the first housing 171.

[0155] Also, since the second housing 173 is located around the first housing 171 and functions to protect the transparent ultrasonic sensor 1, the second housing 173 may have a width and thickness greater than those of the first housing 171.

[0156] Therefore, as Figure 3 shown, the first electrode layer 153 and the first housing 171 may be located within the second housing 173.

[0157] Also, as described above, the outer side surface of the second housing 173 exposed to the outside is covered with the protective layer 11 to prevent noise signals from being introduced into the transparent ultrasonic sensor 1 through the second housing 173.

[0158] As shown in FIG. 2 and Figure 3 shown, since the second housing 173 does not affect the light receiving area of the piezoelectric layer 151, the size of the second housing 173 can be increased as needed.

[0159] Also, threads 1731, connectors, etc. may be formed on the second housing 173 to couple a desired optical component to the second housing 173. In this case, the second housing 173 can function as a coupling portion for coupling with other components.

[0160] The insulating portion 18 is located between the first housing 171 and the second housing 173 that transmit respective corresponding electrical signals to the corresponding electrode layers 153, 155 and is in contact with the corresponding housings 171, 173, and insulates the first housing 171 and the second housing 173, thereby preventing electrical short circuits or shorts, and can function to fix the positions of the first housing 171 and the second housing 173.

[0161] Such an insulating portion 18 may be formed of a transparent insulating material such as non-conductive epoxy resin. As an example of the integrating portion 13, in the case of using a plano-concave acoustic lens, the light and ultrasonic signals reflected by the object 200 and incident are adjusted in focus by the acoustic lens of the integrating portion 13, but light diffusion may occur after passing through the integrating portion 13 (refer to Figure 6a ).

[0162] Therefore, a plano-convex correction lens portion 19 having a shape opposite to that of the acoustic lens of the integrating portion 13 is located behind the rear layer 16 and compensates for this light refraction phenomenon, thereby preventing the light diffusion phenomenon (refer to Figure 6b ).

[0163] At this time, the curvature of the correction lens portion 19 can be selectively used according to the final position of the light.

[0164] Thus, the correction lens unit 19 only affects the focus of light and has nothing to do with the focus of the ultrasonic signal, but the acoustic lens of the integration unit 13 can affect both the focus of the ultrasonic signal and the focus of light.

[0165] The correction lens unit 19 can be omitted as needed, and the correction lens unit 19 can be changed to adjust the focal length of light.

[0166] Moreover, the correction lens unit 19 can have a confocal function of simultaneously adjusting the focus of the ultrasonic signal that is reflected and received and the focus of light. However, when the correction lens unit 19 is equipped with a confocal function, it is necessary to design the correction lens unit 19 in consideration of the form of light before passing through the transparent ultrasonic sensor 1.

[0167] In this example, the correction lens unit 19 is equipped with one lens, but it is not limited thereto. In addition to one lens such as a plano-convex lens, a lens for correcting aberration can be additionally equipped, so that multiple lenses can be equipped.

[0168] The features of the transparent ultrasonic sensor 1 of this embodiment having such a structure and all the components (for example, the protective layer 11 to the rear layer 16, the correction lens unit 19) located in the effective area AR1 of the transparent ultrasonic sensor 1 and made of a transparent material that can transmit light can be as follows.

[0169] First, since the optical impedance matching (i.e., integration) is achieved by the operation of the integration unit 13, the reliability of the signal output from the transparent ultrasonic sensor 1 can be improved.

[0170] Moreover, since the acoustic lens equipped with a focus adjustment function used in the integration unit 13 is used, the focus of the light and the ultrasonic signal reflected by the object 200 can be adjusted, so that the light and the ultrasonic signal can be accurately formed at the desired position of the piezoelectric unit 15. Thus, the clarity of the ultrasonic image obtained from the signal output from the transparent ultrasonic sensor 1 is greatly improved, so that not only the presence or absence of the corresponding object 200 can be grasped, but also the accurate shape of the detected object 200 can be grasped.

[0171] Moreover, as described above, since all the components (for example, the protective layer 11 to the rear layer 16, the correction lens unit 19) constituting the transparent ultrasonic sensor 1 are made of a transparent material such as transparent glass, transparent epoxy resin, transparent silicone grease, etc., the light output from the optical module 100 can directly pass through the transparent ultrasonic sensor 1 and irradiate the object 200 side.

[0172] Thus, the optical system equipped with the transparent ultrasonic sensor 1 can be freely arranged, and the utilization rate of the space for setting the optical system can be improved.

[0173] Moreover, the correction lens unit 19 can be selectively used according to the needs of the user, and the correction lens unit 19 can be changed to adjust the focal length of light.

[0174] Moreover, when a plano-concave optical lens coated for 400 nm - 1000 nm is used as the acoustic lens, light can be transmitted well in the range of 400 nm - 1000 nm, thereby improving the clarity of the ultrasonic image.

[0175] When a plano-concave optical lens is used as the acoustic lens, a light diffusion shape caused by the acoustic lens is generated, but the light diffusion shape can be compensated by the correction lens unit 19, and the focus of light can be adjusted to a desired position. Thus, the selection range of the acoustic lens can be increased by using a compensation lens.

[0176] By adjusting the focus of such an acoustic lens and the correction lens unit 19 to maintain the shape of light, a fine focus can be maintained, and thus a high-resolution optical image (e.g., a photoacoustic image or an optical coherence tomography image) can be obtained.

[0177] Moreover, since the first signal line L1 and the second signal line L2 are respectively connected to the first housing 171 and the second housing 173 constituting the housing of the transparent ultrasonic sensor 1 to apply an electrical signal to the first electrode 153 and the second electrode 155 of the transparent ultrasonic sensor 1, the connection of the signal lines L1 and L2 can be easily implemented.

[0178] Moreover, a thread 1731 or the like can be formed on the second housing 173 as an outer housing to facilitate the connection or coupling with other optical elements. Thus, since the required optical elements are coupled to the second housing 173 located in a part completely unrelated to the path of the light emitted from the optical module 100, light normally and without loss enters the piezoelectric part 15 of the transparent ultrasonic sensor 1 and passes through the center of the transparent ultrasonic sensor 1 in the normal direction, so that the alignment of the light and the ultrasonic signal can be easily achieved.

[0179] Here, "perpendicular" can mean that light travels linearly in a direction perpendicular to the incident surface of the transparent ultrasonic sensor (e.g., the transparent ultrasonic transducer).

[0180] Thus, when light is incident perpendicularly to the ultrasonic sensor, the focal positions of the light and the ultrasonic signal can be accurately aligned, thereby further improving the clarity of the image obtained from the transparent ultrasonic sensor.

[0181] As described above, an integration layer can be provided to minimize the loss of ultrasonic energy in the medium due to the difference in acoustic impedance between air and the medium.

[0182] There can be more than one such integration layer.

[0183] In the comparative example, such an integration layer can be formed as follows.

[0184] When the medium of the ultrasonic signal is water or biological tissue (1.5 Mrayls), in the case where the piezoelectric layer is LNO (34.5 Mrayls) or PMN-PT (37.1 Mrayls), in order to maximize the transmission and reception efficiency of ultrasonic energy, acoustic impedance matching is required. In this case, one or more integration layers composed of a material with an acoustic impedance between 37.1 Mrayls and 1.5 Mrayls may be needed.

[0185] At this time, when generating a specific matching layer using a KLM simulation tool (such as PiezoCAD, PZFLEX, etc.), it is necessary to confirm the waveform of the ultrasonic signal transmitted from water or biological tissue through simulation to find a suitable material for the integration layer. The thickness of the generated integration layer also affects the ultrasonic waveform, so the thickness also has a great impact on the waveform. Therefore, it is necessary to adjust the thickness of the integration layer to find a suitable thickness. Theoretically, the thickness with the minimum loss of wave energy has the minimum loss at the desired thickness of λ / 4 according to the wave equation (c = λ * f, c: speed of sound (about 1480 m / s), λ: wavelength, f: desired center frequency).

[0186] In a general ultrasonic sensor, a mixture of silver powder and epoxy resin (7.9 Mrayls) is usually used to generate the first integration layer. At this time, the acoustic impedance can be adjusted according to the mixing ratio of silver powder and epoxy resin. As an example, it can be silver powder: epoxy resin = 3:1.25.

[0187] Then, the second integration layer can be generated by parylene coating (2.8 Mrayls).

[0188] In the case where the piezoelectric layer is PVDF or PVDF-TrFE (about 4 Mrayls), only parylene coating can be used to generate one integration layer. Here, the integration layer formed by parylene coating can not only function as an integration layer, but also play a role in protecting and insulating from the outside.

[0189] However, in the case of the transparent ultrasonic sensor 1 according to this example, since the components located in the effective region AR1 (e.g., the protective layer 11 to the back layer 16, the correction lens unit 19) are transparent, in the case of LNO or PMN-PT constituting the piezoelectric layer, glass can be used to form the integration unit 13. At this time, according to some differences in the raw materials of the glass (e.g., borosilicate glass = 13 Mrayls, Crown glass = 14.2 Mrayls, Quartz = 14.5 Mrayls, plate glass = 10.7 Mrayls, sodalime glass = 13 Mrayls), the desired glass can be appropriately selected and used.

[0190] Then, a transparent epoxy resin type or silicone grease type (e.g., PDMS) can be used to form the second integration layer (e.g., 2 to 6 Mralys), and parylene coating can be used to form the third integration layer. At this time, the formation of the second integration layer can be omitted, and the second integration layer (e.g., the protective layer 11) can be directly formed on the first integration layer (e.g., the integration unit 13) by parylene coating. In this case, the formation of the desired integration layer can also be implemented by simulating the waveform based on the results of KLM simulation.

[0191] In the transparent ultrasonic sensor 1 according to this example, as an example, an engineering lens made of borosilicate is used as the first integration layer, and the second integration layer is formed on the first integration layer by parylene coating, thereby implementing acoustic impedance matching, external protection, and signal insulation.

[0192] As described above, the optical lens can not only perform the function of acoustic impedance matching but also perform the function of focusing the ultrasonic signal generated in the piezoelectric layer.

[0193] Since the transparent ultrasonic sensor 1 is mainly used for image acquisition, the focusing of the ultrasonic signal is a factor that has a great impact on high resolution and high sensitivity.

[0194] Next, with reference to Figures 7a to 7k , the manufacturing method of the transparent ultrasonic sensor 1 according to this example will be described.

[0195] First, as Figure 7a shown, a piezoelectric layer 151 made of LNO is attached and arranged on the substrate 300. At this time, the piezoelectric layer 151 can have a predetermined transparency in a state where the front surface and the back surface are polished using a high-speed polisher or the like.

[0196] At this time, the thickness of the piezoelectric layer 151 can be changed according to the center frequency of the transparent ultrasonic sensor to be manufactured (usually, thickness = wavelength / 2), and its thickness is constant at all positions, so that the two surfaces of the piezoelectric layer 151 can have flat surfaces.

[0197] Then, as Figure 7b shown, a transparent conductive material such as silver nanowire (AgNW) is coated on one surface of the piezoelectric layer 151 exposed to the outside by a spraying method or a spin coating method to form the first electrode layer 153. At this time, in addition to the coating method, the first electrode layer 153 can be manufactured by various methods.

[0198] As Figure 7c shown, then, a conductive epoxy resin or the like is coated on the edge portion of the first electrode layer 153, and then the annular first housing 171 is arranged and cured so that the first housing 171 adheres to the first electrode layer 153.

[0199] Then, a liquid transparent non-conductive material such as a transparent epoxy resin is injected onto the first electrode layer 153 exposed through the internal space of the first housing 171 surrounded by the first housing 171, and then cured (for example, for 24 hours at room temperature), thereby forming the rear layer 16 in contact with the exposed surface of the first electrode layer 153 ( Figure 7d ). At this time, the thickness of the formed rear layer 16 can be determined according to the protruding height of the first housing 171 located on the first electrode layer 153, and the rear surface as the exposed surface of the rear layer 16 can be a flat surface. Therefore, light or laser passing through the transparent ultrasonic sensor 1 will not be refracted.

[0200] Then, as Figure 7e shown, an annular second housing 173 made of a conductive material having conductivity similar to that of the first housing 171 is attached and arranged at the edge portion of the substrate 300. At this time, as Figure 7e shown, the position of the second housing 173 is arranged at a distance from the first housing 171 on the periphery of the piezoelectric layer 151 where the first housing 171 is installed to be electrically insulated from the first housing 171, and the piezoelectric layer 151 is located in the internal space surrounded by the second housing 173.

[0201] At this time, the height at which the second housing 173 protrudes from the substrate 300 can be the same as the protruding height of the first housing 171.

[0202] Then, a non-conductive epoxy resin as an insulating material is injected between the first housing 171 and the second housing 173 which are separated from each other and then cured, thereby forming an insulating portion 18 on the first housing 171 and the second housing 173 (Figure 7f )。

[0203] At this time, the upper end height of the insulating part 18 can be the same as the protruding height of the first housing 171 and the second housing 173 located on both sides, that is, the same as the upper end height of the first housing 171 and the second housing 173 located on both sides. Through such an insulating part 18, the corresponding parts of the first housing 171 and the second housing 173 are combined with the insulating part 18.

[0204] Thus, when manufacturing the preliminary transparent ultrasonic sensor including the first housing 171 and the second housing 173, the preliminary transparent ultrasonic sensor on the substrate 300 is flipped 180 degrees in the vertical direction, and then the preliminary transparent ultrasonic sensor is arranged on the substrate 300 again ( Figure 7g )。Due to this change in position, the first housing 171 is arranged in contact with the substrate 300, and the other side (for example, the front surface) of the piezoelectric layer 151 is exposed to the outside.

[0205] Then, as Figure 7h shown, on the surface of the exposed piezoelectric layer 151, the surface of the insulating part 18, and the surface of the second housing 173, a layer made of a transparent conductive material such as AgNWs is formed as the second electrode layer 155 through various layer formation methods such as spraying method or spin coating method.

[0206] Then, an integration part 13 is formed at the corresponding position on the exposed second electrode layer 155 by using a transparent glass type, a transparent epoxy resin type, or a transparent silicone grease ( Figure 7i )。The thickness of the integration part 13 that affects the efficiency of the transparent ultrasonic sensor 1 can be determined according to the magnitude of the center frequency of the ultrasonic signal.

[0207] This integration part 13 may not be located at the edge part of the second electrode layer 155.

[0208] Then, as Figure 7j shown, a protective layer 11 is formed on all the exposed surfaces by using a parylene coating method, that is, on the side surface of the second housing 173, on the exposed surface of the integration part 13, and on the surface of the second electrode layer 173 that is exposed without the integration part 13 being arranged.

[0209] Then, after rotating the preliminary transparent ultrasonic sensor manufactured so far 180 degrees in the vertical direction, a concave lens is formed on the exposed rear layer 16 to form a correction lens part 19 ( Figure 7k )。

[0210] Finally, the first signal line L1 and the second signal line L2 are respectively connected to the first housing 171 and the second housing 173 to complete the transparent ultrasonic sensor 1 (refer to Figure 3 )。

[0211] In the case where the correction lens unit 19 is omitted, the preliminary transparent ultrasonic sensor manufactured to Figure 7j can be rotated 180 degrees in the vertical direction, and then the first signal line L1 and the second signal line L2 are respectively connected to the first housing 171 and the second housing 173 to complete the transparent ultrasonic sensor 1.

[0212] The technical features disclosed in each embodiment of the present invention are not limited to that embodiment, and as long as they do not conflict with each other, the technical features disclosed in each embodiment can also be combined and applied to different embodiments from each other.

[0213] As described above, embodiments of the transparent ultrasonic sensor of the present invention have been described. The present invention is not limited to the above-described embodiments and drawings, and various modifications and variations can be made from the perspective of those having ordinary knowledge in the technical field to which the present invention pertains. Therefore, the scope of the present invention is determined not only by the claims of the present application but also by the content equivalent to those claims.

Claims

1. A transparent ultrasonic sensor, comprising: an integration part that performs optical impedance matching and is made of a transparent material; a piezoelectric layer located behind the integration part and made of a transparent material; a first electrode layer and a second electrode layer in a circular planar shape, located behind and in front of the piezoelectric layer respectively and made of a transparent conductive substance respectively; a first housing connected to the first electrode layer; and a second housing connected to the second electrode layer, wherein the diameter of the second electrode layer is greater than the diameter of the first electrode layer, each of the first housing and the second housing is configured in an annular form having an empty space in the middle, the diameter of the second housing is greater than the diameter of the first housing, the first housing is arranged in contact with the edge portion of the first electrode layer, and the second housing is arranged in contact with the edge portion of the second electrode layer in a manner spaced apart from the first housing on the outside of the first housing, and the piezoelectric layer, the first electrode layer and the first housing are arranged in the inner space of the second housing.

2. The transparent ultrasonic sensor according to claim 1, wherein the integration part is provided with an acoustic lens.

3. The transparent ultrasonic sensor according to claim 2, wherein the acoustic lens has one of the forms of a concave lens, a convex lens, and a plano lens.

4. The transparent ultrasonic sensor according to claim 1, wherein the integration part includes at least one of transparent glass, transparent epoxy resin, and transparent silicone grease.

5. The transparent ultrasonic sensor according to claim 1, wherein the piezoelectric layer includes at least one of LNO, PMN-PT, PVDF, and PVDF-TrFE.

6. The transparent ultrasonic sensor according to claim 1, wherein each of the first electrode layer and the second electrode layer includes at least one of silver nanowires, ITO, carbon nanotubes, and graphene.

7. The transparent ultrasonic sensor according to claim 1, wherein the first housing and the second housing include a conductive substance.

8. The transparent ultrasonic sensor according to claim 1, further comprising: a first signal line connected to the first housing; and a second signal line connected to the second housing.

9. The transparent ultrasonic sensor according to claim 1, further comprising: a rear layer arranged in contact with the first electrode layer and attenuating ultrasonic signals.

10. The transparent ultrasonic sensor according to claim 9, wherein the rear layer is surrounded by the first housing.

11. The transparent ultrasonic sensor according to claim 9, wherein the rear layer includes transparent glass or transparent epoxy resin.

12. The transparent ultrasonic sensor according to claim 1, further comprising: an insulating part located between the first housing and the second housing and made of a transparent insulating substance.

13. The transparent ultrasonic sensor according to claim 1, further comprising: a protective layer located in front of the integration part and performing acoustic impedance integration.

14. The transparent ultrasonic sensor according to claim 13, wherein The protective layer includes parylene.

15. The transparent ultrasonic sensor according to claim 1, further comprises: A correction lens, located behind the integration part, adjusting the focus of the light passing through the integration part, and made of a transparent material.

16. The transparent ultrasonic sensor according to claim 15, wherein, The correction lens has a convex shape.

17. A method for manufacturing a transparent ultrasonic lens, comprising the following steps: Dispose a piezoelectric layer on a substrate; Form a transparent first electrode layer in a circular planar shape on the exposed first surface of the piezoelectric layer; Attach and dispose an annular first housing at the edge of the first electrode layer; On the first surface of the first electrode layer surrounded by the annular first housing and exposed through the internal space of the first housing, form a transparent rear layer with a thickness based on the protruding height of the first housing located on the first electrode layer; Attach an annular second housing having a diameter larger than that of the first housing to the edge of the substrate at a distance from the first housing, and dispose the piezoelectric layer, the first electrode layer, and the first housing in the internal space of the second housing; Inject a transparent insulating substance between the first housing and the second housing to form an insulating part, thereby forming a first preliminary transparent ultrasonic sensor; Rotate the first preliminary transparent ultrasonic sensor located above the substrate 180 degrees in the vertical direction and dispose it on the substrate; Form a transparent second electrode layer in a circular planar shape on the exposed second surface of the piezoelectric layer, the surface of the insulating part, and the surface of the second housing; Form a transparent integration part on the second electrode layer; and Form a transparent protective layer on the integration part on the exposed first electrode layer.

18. The method for manufacturing a transparent ultrasonic lens according to claim 17, further comprising the following steps: Flip the transparent ultrasonic sensor formed up to the protective layer 180 degrees in the vertical direction and dispose it on the substrate; and Form a correction lens on the exposed rear layer.

19. The method for manufacturing a transparent ultrasonic lens according to claim 17, further comprising the following steps: Flip the transparent ultrasonic sensor formed up to the protective layer 180 degrees in the vertical direction and dispose it on the substrate; and Connect a first signal line to the first housing and a second signal line to the second housing.

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