Patent Publication Number: US-2019167229-A1

Title: Ultrasound imaging probe, manufacturing method thereof, and ultrasonic imaging device

Description:
TECHNICAL FIELD 
     The present invention relates to an ultrasound imaging probe using an ultrasonic transducer, a manufacturing method thereof, and an ultrasonic imaging device. 
     BACKGROUND ART 
     In an ultrasonic imaging device in which a vascular catheter used in a medical field is attached, for example, a crimped state or the like of the stent and the vascular wall is imaged by radiating an ultrasonic wave on an inspection object part of a blood vessel to detect the ultrasonic wave which is reflected therefrom. 
     A forward-looking member intended to image the front side of the catheter is used to perform the ultrasonic wave inspection on the inside of the blood vessel. A forward-looking catheter is used to mainly image a portion (thrombus) of which the blood vessel is occluded by a tumor or the like. For this reason, in the forward-looking catheter, it is requested that the inside of the blood vessel is imaged with a large field of view. In addition, the length of the thrombus may reach several centimeters, and it is requested to image the deep portion. In the conventional method of radiating the ultrasonic wave and detecting the ultrasonic wave reflected therefrom, the deep portion can be imaged, but it is difficult to secure a visual field for imaging the inside of the entire blood vessel including the thrombus. 
     In this regard, a photoacoustic catheter which captures an image by radiating laser on the inside of the entire blood vessel including the thrombus with a wide angle and detecting the ultrasonic wave output therefrom by an ultrasonic transducer is effective. 
     For example, JP-A-2013-99589 (PTL 1) discloses a structure of an imaging probe in which a hole is formed in a transducer itself, and a lens is arranged in the hole. 
     CITATION LIST 
     Patent Literature 
     PTL 1: JP-A-2013-99589 
     SUMMARY OF INVENTION 
     Technical Problem 
     In the photoacoustic catheter, it is necessary to arrange and fix an acoustic element such as an ultrasonic transducer and an optical element such as an optical fiber or a lens with an accuracy of 100 μm or less. In the assembly of the above-described vascular catheter which transmits and receives an ultrasonic wave, an element component of 1 mm or less is manually positioned under a microscope by a visual observation. In the assembly method, it is difficult to assemble the photoacoustic catheter, and there is a problem to establish a technology which can secure an assembly accuracy of the photoacoustic catheter. 
     Incidentally, the imaging probe described in PTL 1 does not use a substrate (silicon substrate) in which the element of the ultrasonic transducer is formed, and the assembly method of the imaging probe cannot be applied to the component mounting of the photoacoustic catheter. 
     An object of the invention is to provide a technology which can secure an assembly accuracy of an ultrasound imaging probe to improve a resolution performance of an obtained image. 
     The above object and novel features of the invention will become apparent from the description of this specification and the accompanying drawings. 
     Solution to Problem 
     An outline of representative features in embodiments disclosed in this application will be described in brief as follows. 
     An ultrasound imaging probe according to one embodiment includes: a substrate which includes an ultrasonic transducer for detecting an ultrasonic wave formed thereon and a through hole passing through front and rear surfaces; an optical fiber which oscillates a laser; a lens which condenses the laser and is arranged in the through hole; and a tubular housing. The substrate and the optical fiber are fixed to the housing. 
     A manufacturing method of an ultrasound imaging probe according to one embodiment includes: (a) a process of preparing a substrate which includes an ultrasonic transducer for detecting an ultrasonic wave is formed thereon and a through hole passing through front and rear surfaces; and (b) a process of fixing the substrate to the inside of a tubular housing after the process (a). The manufacturing method of the ultrasound imaging probe further includes (c) a process of arranging a lens within the through hole of the substrate after the process (b); and (d) a process of fixing an optical fiber for oscillating a laser to the inside of the housing after the process (c). The substrate and the optical fiber are fixed to the housing. 
     An ultrasonic imaging device according to one embodiment includes: an ultrasound imaging probe which includes a substrate in which an ultrasonic transducer for detecting an ultrasonic wave is formed thereon, and an optical fiber which oscillates a laser; a laser control part which controls the laser; and a receiving part which receives a signal which is converted from the ultrasonic wave by the ultrasonic transducer. The ultrasonic imaging device further includes: an image processing part which performs image processing on the signal received by the receiving part; and a display part which displays images processed by the image processing part. In the ultrasound imaging probe, the laser is condensed by a lens arranged within a through hole included by the substrate, and the substrate and the optical fiber are fixed to a tubular housing. 
     Advantageous Effects of Invention 
     The effects obtained by representative aspects of the invention disclosed in this application will be briefly described below. 
     In the ultrasound imaging probe, it is possible to improve the position accuracy of the acoustic element and the optical element to secure the assembly accuracy of the ultrasound imaging probe, and to improve the resolution performance of the obtained image. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic configuration diagram illustrating one example of an ultrasonic imaging device of an embodiment of the invention. 
         FIG. 2  is a perspective view partially illustrating one example of a use situation of the ultrasonic imaging device of  FIG. 1 . 
         FIG. 3  is a block diagram illustrating one example of a configuration of the ultrasonic imaging device of  FIG. 1 . 
         FIG. 4  is a perspective view illustrating one example of a structure of a catheter provided in the ultrasonic imaging device of  FIG. 1 . 
         FIG. 5  is an enlarged cross-sectional view partially illustrating one example of a structure of a tip part in the catheter of  FIG. 4 . 
         FIG. 6  is a transparent plan view illustrating one example of a positional relation among members in the catheter of  FIG. 5 . 
         FIG. 7  is a cross-sectional view partially illustrating one example (without any deviation) of a relation of a positional deviation between a through hole and a lens in the catheter of  FIG. 5 . 
         FIG. 8  is a cross-sectional view partially illustrating one example (maximum deviation) of the relation of the positional deviation between the through hole and the lens in the catheter of  FIG. 5 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
       FIG. 1  is a schematic configuration diagram illustrating one example of an ultrasonic imaging device of an embodiment of the invention,  FIG. 2  is a perspective view partially illustrating one example of a use situation of the ultrasonic imaging device of  FIG. 1 , and  FIG. 3  is a block diagram illustrating one example of a configuration of the ultrasonic imaging device of  FIG. 1 . 
     The ultrasonic imaging device of the embodiment illustrated in  FIG. 1  will be described. 
     An ultrasonic imaging device  1  illustrated in  FIG. 1  is an inspection device in which a catheter used in a medical field or the like is attached. For example, a crimped state or the like of a stent and a vascular wall is imaged and inspected by radiating laser on an inspection object part of a blood vessel and detecting an ultrasonic wave which is reflected therefrom. 
     In the ultrasonic imaging device  1  of the embodiment, the attached catheter is an ultrasound imaging probe which is also called a photoacoustic catheter  5 . 
     The configuration of the ultrasonic imaging device  1  is described using  FIGS. 1 to 3 . The ultrasonic imaging device  1  includes a main body part  2  which includes a laser control part  2   b , a reception circuit part (receiving part)  2   e , an image processing part  2   f , and the like as illustrated in  FIG. 3 , a catheter connection part  6  which is connected to a connection part  2   a  of the main body part  2  illustrated in  FIG. 1 , and a photoacoustic catheter  5  which is an ultrasound imaging probe connected to the catheter connection part  6 . 
     The ultrasonic imaging device  1  includes a display part  3  which projects the image of the inspection object part and an input part  4  which inputs various pieces of information by a key operation at the time of inspecting. 
     As illustrated in  FIG. 2 , at the time of inspecting, first, a laser  7  is oscillated from an optical fiber  5   d  provided in the photoacoustic catheter  5  with respect to the inspection object part, an ultrasonic wave  8  coming out therefrom is detected and received, and the state of the inspection object part is projected to the display part  3 . Then, depending on the situation, for example, a treatment is performed such that the laser  7  is radiated on a thrombus  9   a  of a blood vessel  9  which is an inspection object part to burn off the thrombus  9   a.    
     As illustrated in  FIGS. 1 to 3 , the photoacoustic catheter (ultrasound imaging probe)  5  which is connected to the main body part  2  of the ultrasonic imaging device  1  through the catheter connection part  6  is provided with an ultrasonic transducer (CMUT (Capacitive Micro-machined Ultrasonic Transducers))  5   b  and the optical fiber  5   d  which oscillates the laser  7 . The ultrasonic transducer  5   b  is a Micro Electro Mechanical Systems (MEMS) sensor, and the ultrasonic transducer  5   b  of the embodiment is, for example, an acoustic element formed in an array type. 
     On the other hand, the main body part  2  of the ultrasonic imaging device  1  is provided with the laser control part  2   b  which controls the oscillation of the laser  7  radiated from the optical fiber  5   d , a bias part  2   c  which supplies the bias current to the ultrasonic transducer  5   b , the reception circuit part (receiving part)  2   e  which receives the signal which is converted from the ultrasonic wave  8  detected by the ultrasonic transducer  5   b  provided in the photoacoustic catheter  5 , and the image processing part  2   f  which performs image processing on the signal received by the reception circuit part  2   e.    
     The main body part  2  is provided with the bias part  2   c  which supplies the bias current to the ultrasonic transducer  5   b  and the control part  2   d  which drives the optical fiber  5   d  or controls the image processing part  2   f.    
     The display part  3  of the ultrasonic imaging device  1  is a monitor which displays images processed by the image processing part  2   f.    
     Accordingly, in the ultrasonic imaging device  1 , it is possible to image the front side of the catheter by the photoacoustic catheter  5 . 
     When the thrombus is imaged and treated by using the ultrasonic imaging device  1 , first, the photoacoustic catheter  5  is advanced close to the thrombus under the guidance using an X-ray image. Then, as illustrated in  FIG. 2 , the optical fiber  5   d  is driven to be rotated, the laser  7  is radiated on the thrombus  9   a , the ultrasonic wave  8  coming out therefrom is detected by the ultrasonic transducer  5   b , and the state of the thrombus  9   a  is projected to the display part  3 . 
     Next, the laser  7  is similarly radiated on the thrombus  9   a  while checking the image of the display part  3 , and the thrombus  9   a  is burnt off to be removed. Accordingly, the occluded place of the blood vessel  9  is penetrated. Thereafter, the stent is arranged within the blood vessel  9 , and the stent is expanded. 
     The laser  7  is radiated by the photoacoustic catheter  5  to image and check the indwelled state of the stent. 
     Next, a specific structure of the photoacoustic catheter  5  which is the ultrasound imaging probe of the embodiment will be described. 
       FIG. 4  is a perspective view illustrating one example of the structure of the catheter provided in the ultrasonic imaging device of  FIG. 1 .  FIG. 5  is an enlarged cross-sectional view partially illustrating one example of the structure of the tip part in the catheter of  FIG. 4 .  FIG. 6  is a transparent plan view illustrating one example of a positional relation among members in the catheter of  FIG. 5 . 
     As illustrated in  FIG. 1 , the photoacoustic catheter (ultrasound imaging probe)  5  is connected to the catheter connection part  6  which is connected to the connection part  2   a  of the main body part  2  of the ultrasonic imaging device  1 , and is an elongated tubular member as illustrated in  FIG. 4 . 
     As illustrated in  FIG. 5 , near the tip part of the photoacoustic catheter  5 , the ultrasonic transducer  5   b  for detecting the ultrasonic wave  8  illustrated in  FIG. 2  is formed on the surface thereof, and there are provided with a silicon substrate (substrate)  5   a  including a through hole  5   c  passing through front and rear surfaces and a lens  5   e  which condenses the laser  7  and is arranged in the through hole  5   c . That is, the silicon substrate  5   a  and the lens  5   e  are arranged within the tip part of a housing  5   f . The housing  5   f  has a cylindrical shape (tubular shape) and is an elongated tubular member. In  FIG. 5 , an electronic circuit substrate or a cable required to transfer the signal of the ultrasonic transducer  5   b  is omitted. In  FIG. 5 , a cable for transferring a voltage signal required to drive an actuator  5   n  is omitted. 
     The optical fiber  5   d  which oscillates the laser  7  is stored in the housing  5   f  in the state of being arranged along the central axis thereof. 
     In the photoacoustic catheter  5  of the embodiment, the silicon substrate  5   a  and the optical fiber  5   d  are fixed to a part of the housing  5   f  within the housing  5   f.    
     In the silicon substrate  5   a , the cylindrical through hole  5   c  is formed in the central portion, and thus the planar shape thereof is a ring shape and a disc shape. On the other hand, the housing  5   f  has a cylindrical appearance and also has an almost cylindrical hollow portion therein. Further, the outer circumferential portion of the silicon substrate  5   a  is fixed to an inner circumferential wall  5   fc  of the housing  5   f.    
     The ultrasonic transducer  5   b  is an electrostatic capacitance sensor which is formed on the silicon substrate  5   a  having a ring shape in plan view and is arranged to surround the through hole  5   c  in plan view as illustrated in  FIG. 6 . Further, the cylindrical lens  5   e  is arranged on the inner circumferential side of the ultrasonic transducer  5   b . That is, the cylindrical lens  5   e  is arranged within the cylindrical through hole  5   c  of the central portion of the silicon substrate  5   a.    
     A gap  10  between the cylindrical lens  5   e  and the through hole  5   c  of the silicon substrate  5   a  is filled with a transparent resin  5   g . Further, the planar shape and the positional relation regarding the housing  5   f , the silicon substrate  5   a , the ultrasonic transducer  5   b , the resin  5   g , and the lens  5   e  are illustrated in  FIG. 6 . 
     As illustrated in  FIG. 5 , the ultrasonic transducer  5   b  formed on the silicon substrate  5   a  is covered with a protective film  5   h  and is protected by the protective film  5   h.    
     The lens  5   e  has a first surface  5   ea  which intersects with the oscillating direction P of the laser  7  and a second surface  5   eb  which is on an opposite side thereto. The second surface  5   eb  which is positioned on the outside (tip side) between the first surface  5   ea  and the second surface  5   eb  is covered with a transparent glass cover  5   i  which contacts the second surface  5   eb . That is, the glass cover  5   i  has a disc shape and is arranged to block the opening portion on the tip side of the through hole  5   c  of the silicon substrate  5   a.    
     The ultrasonic transducer  5   b  is arranged on the circumferential outside of the disc-shaped glass cover  5   i , and the circumferential outside is covered with the protective film  5   h  which fills the position between the glass cover  5   i  and the housing  5   f.    
     The side surface (third surface)  5   ec  which is positioned between the first surface  5   ea  and the second surface  5   eb  of the lens  5   e  is partially covered with the transparent resin  5   g  as described above. Specifically, the above-described gap  10 , which is formed in the through hole  5   c  of the silicon substrate  5   a  with the inner wall of the through hole  5   c  of the silicon substrate  5   a , the side surface  5   ec  of the lens  5   e , and a part of the glass cover  5   i , is filled with the transparent resin  5   g.    
     A resin sheath  5   k  is provided outside the housing  5   f  to cover the housing  5   f . Accordingly, the area between the sheath  5   k  and the housing  5   f  serves as a flow path  5   m  of a blood removal liquid. 
     Herein, in the photoacoustic catheter  5  of the embodiment, the silicon substrate  5   a  and the optical fiber  5   d  are fixed to the housing  5   f . Specifically, the silicon substrate  5   a  is arranged on a ring-shaped support part  5   fa  protruding from the inner circumferential wall  5   fc  toward the center of the housing  5   f  in the housing  5   f , and is fixed to the support part  5   fa.    
     On the other hand, the optical fiber  5   d  is arranged along the extending direction of the housing  5   f  in the inner central portion of the cylindrical housing  5   f , and is rotatably supported by the support part  5   fb  protruding from the inner circumferential wall  5   fc  of the housing  5   f.    
     Accordingly, in the photoacoustic catheter  5  of the embodiment, the silicon substrate  5   a  and the optical fiber  5   d  are fixed to the housing  5   f . Thus, it is possible to align three axes of the ultrasonic transducer  5   b  formed on the silicon substrate  5   a , the lens  5   e  arranged in the through hole  5   c  of the silicon substrate  5   a , and the optical fiber  5   d.    
     That is, the positioning of the lens  5   e  is determined by the through hole  5   c  of the silicon substrate  5   a , and the positioning of the silicon substrate  5   a  and the optical fiber  5   d  are determined by the housing  5   f . Thus, it is possible to align three axes of the ultrasonic transducer  5   b , the lens  5   e , and the optical fiber  5   d . In other words, a center C 3  of the optical fiber  5   d  illustrated in  FIG. 5 , a center C 1  of the silicon substrate  5   a  illustrated in  FIG. 8  which will be described later, and a center C 2  of the lens  5   e  can be matched with a high position accuracy. 
     As a result, it is possible to secure the assembly accuracy in the photoacoustic catheter (ultrasound imaging probe)  5 . In other words, in the photoacoustic catheter  5 , it is possible to establish a component mounting method in which the position accuracy of the laser  7  (lens  5   e ) and the ultrasonic transducer  5   b  is improved. 
     For example, in the photoacoustic catheter  5  of the embodiment, it is possible to arrange and fix the acoustic element (ultrasonic transducer  5   b ) and the optical element (the optical fiber  5   d  or the lens  5   e ) with the accuracy of about 100 μm. 
     In the photoacoustic catheter  5  of the embodiment, the optical fiber  5   d  is attached such that the tip side thereof is rotatable. Specifically, as illustrated in  FIG. 5 , the actuator  5   n  is attached on the tip side of the optical fiber  5   d , and the tip side of the optical fiber  5   d  can be rotated. 
     Accordingly, it is possible to secure the viewing angle of the laser  7  which is oscillated from the optical fiber  5   d.    
     Herein, for example, preferably, the housing  5   f  is formed of a metal such as an SUS (stainless steel) or a resin. When the housing  5   f  is formed of the SUS, it is possible to improve the processing accuracy of the housing  5   f  since the SUS is a material having a high processing accuracy. It is possible to improve the accuracy of the housing  5   f  positioning the silicon substrate  5   a  or the optical fiber  5   d.    
     However, the housing  5   f  may be formed of a resin on which a fine processing can be performed. 
     The transparent resin  5   g  with which the gap  10  between the lens  5   e  and the through hole  5   c  of the silicon substrate  5   a  is filled is, for example, a UV curable resin, a thermosetting resin, or a two-liquid curable resin. 
     The lens  5   e  is, for example, a GRIN lens. 
     Next, the positional deviation amount between the through hole  5   c  formed in the silicon substrate  5   a  and the lens  5   e  will be described.  FIG. 7  is a cross-sectional view partially illustrating one example (without any deviation) of the relation of the positional deviation between the through hole and the lens in the catheter of  FIG. 5 .  FIG. 8  is a cross-sectional view partially illustrating one example (maximum deviation) of the relation of the positional deviation between the through hole and the lens in the catheter of  FIG. 5 . 
     It is ideal that the position of the lens  5   e  with respect to the through hole  5   c  of the silicon substrate  5   a  is the position as illustrated in  FIG. 7 . That is, the lens  5   e  is arranged in the center of the through hole  5   c . Herein, the center C 1  of the through hole  5   c  is arranged to match the center C 2  of the lens  5   e  when the diameter L 1  of the lens  5   e  is 350 μm, the diameter L 2  of the through hole  5   c  is 500 μm, and the range L 3  of the laser scan is 200 μm. Further, since the range L 3  of the laser scan is 200 μm, the laser scan can be performed on the vicinity of the center with respect to 350 μm of the diameter L 1  of the lens  5   e.    
       FIG. 8  is the case where the center C 2  of the lens  5   e  is arranged to be maximally deflected to the left side with respect to the center C 1  of the through hole  5   c  (a case where an allowable deviation amount is maximum). In this case, the end of the range L 3  of the laser scan is overlapped with the end of the range of the diameter L 1  of the lens  5   e , and the range L 3  of the laser scan indicates a range where the positional deviation of the lens  5   e  is maximum when the range is set not to be out of the lens. 
     In the positional deviation of the lens  5   e  with respect to the through hole  5   c  of the silicon substrate  5   a , it is important to keep the range L 3  of the laser scan from being out of the lens. If the range L 3  of the laser scan is out of the lens, the power of the laser  7  is reduced, the desired photoacoustic signal is not generated, and the quality of the captured image is lowered due to the sensitivity deficiency. At that time, the deviation amount of the lens  5   e  with respect to the through hole  5   c  is associated with the range L 3  of the laser scan and the diameter L 1  of the lens  5   e.    
     Therefore, a case where the deviation amount of the lens  5   e  is maximum as illustrated in  FIG. 8  is the limit of the allowable range. In the structure illustrated in  FIG. 8 , a difference Z between the diameter L 2  of the through hole  5   c  of the silicon substrate  5   a  and the diameter L 1  of the lens  5   e  is 150 μm, and the limit value of the numerical value of the difference Z is 150 μm. That is, the difference Z between the diameter L 2  of the through hole  5   c  of the silicon substrate  5   a  and the diameter L 1  of the lens  5   e  is preferably within 150 μm. 
     The difference Z between the diameter L 2  of the through hole  5   c  and the diameter L 1  of the lens  5   e  is within 150 μm as described above, thereby avoiding the reduction of the power of the laser  7  and preventing the lowering of the quality of the captured image. 
     The ultrasonic imaging device  1  illustrated in  FIG. 1  according to the embodiment includes the above-described photoacoustic catheter (ultrasound imaging probe)  5  illustrated in  FIG. 5 . That is, in the above-described photoacoustic catheter  5 , the laser  7  is condensed by the lens  5   e  which is arranged within the through hole  5   c  included in the silicon substrate  5   a , and the silicon substrate  5   a  (ultrasonic transducer  5   b ) and the optical fiber  5   d  are respectively fixed to a part of the housing  5   f  inside the tubular housing  5   f.    
     According to the ultrasonic imaging device  1  of the embodiment, in the photoacoustic catheter  5  included in the ultrasonic imaging device  1 , the lens  5   e  is arranged in the through hole  5   c  of the silicon substrate  5   a , and the silicon substrate  5   a  and the optical fiber  5   d  are fixed to the housing  5   f , thereby improving the position accuracy of the ultrasonic transducer  5   b  (acoustic element) on the silicon substrate  5   a  and an optical element such as the optical fiber  5   d  or the lens  5   e.    
     As a result, it is possible to improve the acoustic performance of the ultrasonic imaging device  1 . Specifically, in the ultrasonic imaging device  1 , the assembly accuracy of the photoacoustic catheter  5  included in the ultrasonic imaging device  1  can be secured. Accordingly, in the ultrasonic imaging device  1 , the resolution performance of the obtained image can be improved. 
     The ultrasonic imaging device  1  of the embodiment includes the photoacoustic catheter  5 . Thus, the thrombus can be removed mainly with respect to chronic total occlusion lesion (CTO) by the front-side imaging of the catheter and the laser radiation with high power. As a result, it is possible to perform the stent treatment of the CTO which is considered to be difficult. 
     Next, the manufacturing method of the photoacoustic catheter (ultrasound imaging probe)  5  of the embodiment will be described. In the embodiment, described is a case in which the photoacoustic catheter  5  is manufactured by using the manufacturing process of the semiconductor process. 
     First, as illustrated in  FIG. 5 , the electrostatic capacitance ultrasonic transducer  5   b  is formed on the silicon substrate  5   a  by using the semiconductor process. That is, on the silicon substrate  5   a , the ultrasonic transducer  5   b  which is an electrostatic capacitance type and an MEMS sensor is formed to surround the through hole  5   c  in plan view. 
     Next, the through hole  5   c  which passes through the front and rear surfaces is formed in the central portion of the silicon substrate  5   a . Here, for example, the through hole  5   c  is formed in the substantially central portion of the silicon substrate  5   a  by etching processing. 
     That is, the ultrasonic transducer (CMUT)  5   b  which detects the ultrasonic wave is formed on the surface, and the silicon substrate  5   a  which includes the through hole  5   c  passing through the front and rear surfaces is prepared on the inner circumferential side of the ultrasonic transducer  5   b . Further, the elongated housing  5   f  having a tubular shape is prepared. The outer circumferential shape (circular shape) of the silicon substrate  5   a  is also formed by the etching processing at the time of forming the through hole  5   c . That is, the silicon substrate  5   a  is formed in a disc shape by the same etching processing with the through hole  5   c . Accordingly, the silicon substrate  5   a  also has a ring shape (disc shape) in plan view. 
     However, each of the through hole  5   c  and the outer circumferential shape of the silicon substrate  5   a  may be processed by separate processes. 
     Next, the silicon substrate  5   a  in which the ultrasonic transducer  5   b  is formed thereon is fixed to the inside of the tubular housing  5   f . Herein, in the housing  5   f , the silicon substrate  5   a  is fixed to the support part  5   fa  protruding from the inner circumferential wall  5   fc  of the housing  5   f . At that time, the outer circumferential portion of the silicon substrate  5   a  is fixed to the inner circumferential wall  5   fc  of the housing  5   f , and is arranged on the support part  5   fa . Accordingly, the silicon substrate  5   a  and the ultrasonic transducer  5   b  are positioned by the inner circumferential wall  5   fc  of the housing  5   f.    
     Next, the transparent glass cover  5   i  is attached to the silicon substrate  5   a . At that time, on the inner circumferential side of the ultrasonic transducer  5   b  formed on the silicon substrate  5   a , the disc-shaped glass cover  5   i  is attached to the silicon substrate  5   a  to block the opening portion on the tip side of the through hole  5   c  of the silicon substrate  5   a.    
     Accordingly, in plan view, the ultrasonic transducer  5   b  is arranged between the housing  5   f  and the glass cover  5   i.    
     Next, the area between the glass cover  5   i  and the housing  5   f  is filled with the protective film  5   h  which protects the ultrasonic transducer  5   b.    
     Next, both sides of the housing  5   f  are reversed, and the cylindrical lens  5   e  is arranged within the through hole  5   c  of the silicon substrate  5   a  in the state (a state where the opening portion of the through hole  5   c  of the silicon substrate  5   a  is directed upward). 
     At that time, the lens  5   e  is fitted into the through hole  5   c  to contact the second surface  5   eb  of the lens  5   e  with the glass cover  5   i . Further, after the lens  5   e  is arranged in the through hole  5   c  of the silicon substrate  5   a , the gap  10  between the lens  5   e  and the through hole  5   c  is filled with the transparent resin  5   g.    
     Specifically, the transparent resin  5   g  is poured into the gap  10  formed by the cylindrical lens  5   e , the inner wall of the through hole  5   c  of the silicon substrate  5   a , and the glass cover  5   i  with the disc shape to firmly fix the lens  5   e.    
     Accordingly, the cylindrical lens  5   e  is positioned by the through hole  5   c  of the silicon substrate  5   a.    
     Next, the optical fiber  5   d  which oscillates the laser  7  is fixed inside the housing  5   f . Specifically, in the housing  5   f , the optical fiber  5   d  is fixed to the support part  5   fb  which protrudes from the inner circumferential wall  5   fc  of the housing  5   f . At that time, the fixing position of the optical fiber  5   d  is adjusted such that the center C 1  of the disc-shaped silicon substrate  5   a  illustrated in  FIG. 8  matches the center C 3  of the optical fiber  5   d  illustrated in  FIG. 5 . For example, the adjusting method of the optical fiber  5   d  may be performed such that the laser for adjustment is radiated from the optical fiber  5   d , and the laser is radiated on a predetermined position. For example, the optical fiber  5   d  is easily adjusted when visible light such as red laser is used as the laser for adjustment. 
     When the fixing position of the optical fiber  5   d  is adjusted, the actuator  5   n  may be driven to check whether the laser  7  radiated from the optical fiber  5   d  is rotated within a predetermined range. 
     Next, the outer circumferential portion of the housing  5   f  is covered with the resin sheath  5   k . Accordingly, the photoacoustic catheter  5  in which the silicon substrate  5   a  and the optical fiber  5   d  are fixed to the housing  5   f  is assembled completely. 
     In the assembly of the photoacoustic catheter  5  of the embodiment, by the etching processing of the semiconductor manufacturing process, the through hole  5   c  of the silicon substrate  5   a  is formed, and the outer circumferential portion of the silicon substrate  5   a  is formed in a circular shape. Therefore, it is possible to improve the processing accuracy of the through hole  5   c  and the inner circumference of the substrate. 
     Accordingly, it is possible to improve the positioning accuracy of the lens  5   e  arranged within the through hole  5   c  or the positioning accuracy of the silicon substrate  5   a  attached to the inside of the housing  5   f . As a result, it is possible to improve the position accuracy of the lens  5   e  and the ultrasonic transducer  5   b  on the silicon substrate  5   a . That is, it is possible to improve the assembly accuracy of the photoacoustic catheter  5 , and it is possible to improve the resolution performance of the obtained image in the ultrasonic imaging device  1  using the photoacoustic catheter  5 . 
     In the photoacoustic catheter  5  of the embodiment, since the optical fiber  5   d  is rotatable, it is possible to rotate and radiate the laser  7  and to widen the angle of the visual field as compared to the probe which performs the ultrasonic wave radiation. 
     Since the ultrasonic transducer  5   b  is formed on the silicon substrate  5   a  by the semiconductor manufacturing process, the ultrasonic transducer  5   b  can be formed on the silicon substrate  5   a  with a high position accuracy. 
     Hereinbefore, the invention made by the present inventors has been described in detail based on the embodiment. However, the invention is not limited to the above-described embodiment and includes various modifications. For example, the above-described embodiment is intended to be illustrative of the invention in an easily understandable manner, and the invention is not necessarily limited to the one that includes all of the components described in the embodiment. 
     Some of a configuration of one embodiment can be substituted by the configuration of another embodiment. In addition, the configuration of the another embodiment can be added to the configuration of the one embodiment. Also, in some of the configuration of each embodiment, addition of another configuration, deletion and substitution are possible. Each member or a relative size in the drawings is simplified and idealized for explaining the invention in an easily understandable manner, and has more complicated shapes when mounted. 
     In the embodiment, the description is given about a case where the optical fiber  5   d  is fixed to the support part  5   fb  of the housing  5   f . However, the silicon substrate  5   a  may be formed to be thick by sticking the silicon substrates  5   a , and the optical fiber  5   d  may be supported in the structure which is formed by the assembly using the semiconductor manufacturing process. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1 : ultrasonic imaging device 
               2 : main body part 
               2   a : connection part 
               2   b : laser control part 
               2   c : bias part 
               2   d : control part 
               2   e : reception circuit part (receiving part) 
               2   f : image processing part 
               3 : display part 
               4 : input part 
               5 : photoacoustic catheter (ultrasound imaging probe) 
               5   a : silicon substrate (substrate) 
               5   b : ultrasonic transducer 
               5   c : through hole 
               5   d : optical fiber 
               5   e : lens 
               5   ea : first surface 
               5   eb : second surface 
               5   ec : side surface (third surface) 
               5   f : housing 
               5   fa : support part 
               5   fb : support part 
               5   fc : inner circumferential wall 
               5   g : resin 
               5   h : protective film 
               5   i : glass cover 
               5   k : sheath 
               5   m : flow path 
               5   n : actuator 
               7 : laser 
               8 : ultrasonic wave 
               9 : blood vessel 
               9   a : thrombus 
               10 : gap