JP2017047180A - Transducer array, and acoustic wave measurement apparatus including transducer array - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that, when a plurality of transducers each having a rectangular receiving surface on a recessed support part having a quadric surface of revolution, if the transducers are disposed with their vertices of outer edges of the receiving surfaces brought close to each other, a spacial frequency of a transducer arrangement space is reduced, and resolution power of an acoustic wave image is limited.SOLUTION: The transducer array includes: a support part, the inner surface of which is defined by a quadric surface of revolution formed according to an imaginary quadratic curve rotating about an imaginary rotation axis and having a plurality of openings; and a plurality of transducers each of which includes a receiving surface having a substantially parallelogram shape so as to be fitted in the opening. The receiving surface is arranged in the transducer array such that any one of the four vertices is closer to the imaginary rotation axis than the other three vertices.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a probe array for measuring an acoustic wave, and more particularly to a probe array for measuring an acoustic wave generated by a photoacoustic effect.

  A photoacoustic tomography (PAT) diagnostic apparatus using a photoacoustic effect is known. In such an apparatus, the object is irradiated with illumination light (near infrared) from an Nd: YAG laser pulse light source, and at that time, an acoustic wave generated by the photoacoustic effect inside the object is irradiated with a two-dimensional or three-dimensional array probe (probe). The image is generated by the toucher array and displayed.

  Patent Document 1 discloses a probe in which a plurality of probes are arranged in a curved support structure in order to increase the accuracy of separation and synthesis of acoustic wave signals for each propagation path from acoustic waves propagated from a subject. A photoacoustic measurement device with an array is disclosed. Further, the probe disclosed in Patent Document 1 is a piezoelectric element type having a circular receiving surface.

JP-T-2001-507952

  It is known to form a probe composed of a CMUT (Capacitive Micromachined Ultrasonic Transducer) element having high density, high sensitivity, and wide reception band characteristics by a micro electro mechanical system technology. The microelectromechanical system technology is also referred to as MEMS (Micro Electro Mechanical Systems) technology, and is hereinafter referred to as MEMS in the present specification.

  Since the CMUT element is formed by a semiconductor process, the CMUT element is cut out by using a dicing cut technique that can be cut out from the semiconductor wafer 18 in a predetermined shape and size. Therefore, in order to increase the yield from the semiconductor wafer, the outer edge shape of the CMUT element is not a circle as in the cited document 1, but a parallelogram including a square.

  When a probe having such a parallelogram receiving surface is mounted on the probe array, the probe is arranged in an array in which one vertex defining the receiving surface and one vertex defining the adjacent receiving surface are close to each other. As a result, the mounting density of the tentacles decreased, and the resolution of the image was limited. In addition, when one of the vertices that define the receiving surface and the side that defines the adjacent receiving surface are close to each other, the effective receiving area overlaps and crosstalk occurs, leading to a problem that the resolution of the image is limited. Became. Further, in this aspect, if the area of the receiving surface per probe is reduced in order to ensure the mounting density of the receiving surface, the receiving area is limited, and the receiving sensitivity of the probe array is reduced. There was a problem that it was difficult to obtain deep information.

  The probe array according to the present invention includes a plurality of probes that are connected to a support portion having a bowl-shaped inner surface and each receiving surface is directed to the inner side of the inner surface, and converts an acoustic wave into an electric signal. Wherein the inner surface of the support portion is defined by a rotating quadratic curved surface obtained by rotating a virtual quadratic curve around a virtual rotation axis. A substantially parallelogram-shaped receiving surface defined by two tops, and a conversion element for converting an acoustic wave received by the receiving surface into an electrical signal, wherein the receiving surface has one of the four tops. , It is characterized by being closer to the virtual rotation axis than the other three apexes.

Further, the probe array of the present invention is a probe array having a bowl-shaped support portion for supporting a plurality of probes,
The probe has a substantially parallelogram receiving surface for receiving acoustic waves,
The plurality of receiving surfaces included in the predetermined region of the support part are a plurality of right-handed virtual spirals along the inner surface from the center side of the bowl-shaped inner surface of the support part, and a left-hand winding intersecting them. The plurality of probes are supported by the support portion so as to be arranged on a lattice formed by intersections with the plurality of virtual spirals.

  According to the present invention, it is possible to provide a probe array that acquires an acoustic wave image having both resolution and sensitivity when applied to acoustic wave measurement. Moreover, according to this invention, it becomes possible to provide the acoustic wave measuring apparatus excellent in imaging | photography quality.

It is an overhead view (a), a top view (b), a partially enlarged view (c), and a top view (d) of the probe array according to the first embodiment of the present invention. It is a block diagram of the acoustic wave measuring apparatus which measures the photoacoustic wave in connection with 2nd Embodiment of this invention. It is a conceptual diagram which shows the CMUT element formed on the semiconductor wafer. It is a conceptual diagram which shows the scanning locus | trajectory of the support part vertex of a probe array. It is sectional drawing which shows the cross section of the probe array in connection with 1st Embodiment of this invention. It is sectional drawing (a)-(d) which shows embodiment of a support part. It is a top view (a)-(d) showing an embodiment of a receiving surface.

[Embodiment]
<Acoustic wave measuring device>
FIG. 2 is a block diagram showing a second embodiment in which the probe array 32 of the present invention is applied to an acoustic wave measuring device 21 that measures photoacoustic waves. The support base 1 includes a support surface 25 that supports the subject 24 from below, and an insertion port 12 that is provided on the support surface and into which the subject 20 is inserted downward. It is held on a holding member 11 installed on the support base 1. The subject 20 includes the breast, limb, head, etc. of the subject 24. The holding member 11 has a bowl shape so that the subject 20 can be easily held.

  The probe array 32 transmits an acoustic wave to the subject 20 and receives the acoustic wave reflected by the subject 20 by the probe array. Alternatively, the probe array 32 acoustically generates a pressure elastic wave generated as a result of local and short-time expansion / contraction change of the subject 20 by pulse light irradiated from the light irradiation unit 31 described later to the inside of the subject 20. Receive as a wave.

  The probe array 32 is arranged so that the receiving surface 10 of the probe 321 faces the subject 20. The probe 321 is efficiently connected to the liquid tank 36 and the support unit 322 so that the receiving surface 10 faces the inside of the liquid tank 36, thereby efficiently acquiring the acoustic wave propagating from the subject 20. It is possible to do.

  A space between the probe array 32 and the holding member 11 is filled in a liquid tank 36 in which a matching liquid 35 is stored. The probe array 32 is connected to a liquid tank 36 in which the matching liquid 35 is filled. It can also be said that the probe array 32 forms part of the configuration of the liquid tank 36 filled with the matching liquid 35. The liquid tank 36 has an opening 16 that is opened acoustically at a position overlapping the insertion port 12 so that the subject 20 can be brought into acoustic contact with the stored matching liquid 35. The probe array 32 is connected to the liquid tank 35 on the side facing the opening 16.

  As the matching liquid 35, water whose acoustic impedance is close to the tissue of the subject as compared with air is used. As the matching liquid 35, gel, gel, or the like can be used in addition to water.

  The probe array 32 includes a camera 33 for observing the state in which the subject 20 is held by the holding member 11, a probe 321, and a liquid tank scanning unit 34 that moves two-dimensionally in a horizontal plane (XY plane). Have.

  The liquid tank scanning unit 34 moves the liquid tank 36 relative to the insertion port 12 to cause the reception area of the probe array 32 to scan two-dimensionally in the horizontal plane, and to detect the subject 20 and the reception area. Repeat. In the present embodiment, the light irradiation region that is irradiated from the light irradiation unit 31 and that is not illustrated is overlapped with the subject 20 so that the light irradiation region can be two-dimensionally scanned in a horizontal plane. I can say that.

  An XY liquid tank scanning unit in which the liquid tank scanning unit 34 is combined with a linear guide (not shown), a feed screw mechanism, a motor, and the like is also included in the present invention.

  The signal processing unit 4 performs AD conversion and performs signal processing on digital data (acoustic data). The image generation unit 6 generates a two-dimensional or three-dimensional sound image using the sound data. The display unit 7 displays the generated acoustic image and the image acquired by the camera 33.

<Holding member>
The holding member 11 has a holding function for holding the subject 20 in a predetermined shape during the measurement period, and is configured to prevent acoustic waves from reaching the probe array 32 from propagating from the subject 20. Has impedance. The holding member 11 is selected according to the form of the subject 20, but when the subject 11 is a breast, a bowl-shaped curved surface support portion is used. As the holding member 11, a plurality of replacement support portions having a size and a curvature corresponding to the size of the subject are prepared, or a flexible member such as an elastomer is applied.

  The holding member 11 is thin so as to easily transmit acoustic waves, and a thickness of 0.05 mm to 1.0 mm or the like is applied. Moreover, the holding member 11 is comprised by the translucent member which permeate | transmits the pulsed light irradiated from the light irradiation part 31 in this embodiment. From the present embodiment, if the acoustic wave measuring apparatus (not shown) excluding the light irradiation unit 31, the light guide unit 51, and the light source 5, the translucency of the holding member 11 is not necessarily required.

  The holding member 11 is preferably composed of a member having a strength capable of withstanding the load of the subject 20 in terms of maintaining the imaging posture, and PET (polyethylene terephthalate) is applied.

<Light source>
The light source 5 generates a photoacoustic wave in the subject by irradiating the subject 20 with pulsed light. When the subject 20 is a living body, the light source 5 emits light having a specific wavelength that is absorbed by a specific component among the components constituting the subject 20. The light source 5 may be provided integrally with the probe array 32, but is optically connected separately from the probe array 32 via the light guide means 51 as in this embodiment. May be.

  The light source 5 is preferably a pulse light source that can generate pulsed light having a pulse width of several nanoseconds to several hundreds of microseconds as irradiation light. In the present embodiment, the pulse width of 10 to 100 nanoseconds can be adjusted from the intention of efficiently generating photoacoustic waves.

  The light source 5 is preferably a laser because a high output can be obtained, but a light emitting diode or the like can be used instead of the laser. As the laser, various lasers such as a solid laser, a gas laser, a fiber laser, a dye laser, and a semiconductor laser can be used. The timing, waveform, intensity, etc. of irradiation are controlled by a light source control unit (not shown). In the present invention, the wavelength of the light source used is preferably an infrared wavelength at which light propagates to the inside of the subject. The light emission center wavelength of the light source 5 of this embodiment is near infrared light of 500 nm or more and 1200 nm or less.

<Light guide means>
The light emitted from the light source 5 is guided to the subject 20 by the light guide 51 while being processed into a desired light distribution shape. The light guide means 51 includes an optical fiber, an articulating arm in which a mirror is incorporated in a lens barrel, and the like.

  The other light guide means 51 is, for example, a mirror that reflects light, a lens that collects or enlarges light, or changes its shape, or a diffusion plate that diffuses light.

<Probe array>
FIG. 1 is an overhead view (a), top views (b) and (d), and a partially enlarged view (c) showing a probe array 32 according to the first embodiment of the present invention. FIG. 6 is a cross-sectional view of the probe array 32 according to the first embodiment of the present invention.

  As shown in FIG. 6, the probe array 32 includes a bowl-shaped support portion 322 provided with a plurality of openings 40 that are acoustically opened, and each of the plurality of openings is connected to each of the plurality of openings. A plurality of probes 321 for converting the signal into an electric signal. In other words, the probe array 32 is connected so that the bowl-shaped support part 322 whose inner surface is defined by a rotating quadratic curved surface and each receiving surface 10 face the inside of the bowl-shaped inner surface, A plurality of probes 321 for converting acoustic waves into electrical signals. The rotating quadric surface will be described later.

  The probe array 32 of the present embodiment is applied to an acoustic wave measuring device 21 that measures photoacoustic waves, as shown in FIGS. And a camera 33 for observing the holding state of the light irradiation unit 31, the probe 321, and the subject 20.

  The present invention is an array of a plurality of receiving surfaces in a probe array in which the shape of the inner surface is defined by a rotating quadratic curved surface, which will be described later.

<Probe>
The probe 321 detects acoustic waves and converts them into electrical signals that are analog signals. Any element that can detect acoustic waves, such as a conversion element using a piezoelectric phenomenon, a conversion element using optical resonance, or a conversion element using a change in capacitance, may be used.

  In the present embodiment, a plurality of probes 321 are arranged on the support portion 322 at intervals, thereby forming a probe array 32 having a multidimensional array of probes. By using such a multidimensional array element, acoustic waves can be detected at a plurality of locations at the same time, and the detection time can be shortened.

  As one of the probes, a capacitive probe that is created using a micromachining process has been developed. The capacitance-type probe has a cell including a vibration film supported at a distance from the lower electrode, and an upper electrode disposed on the surface of the vibration film. Such a capacitive probe is called a CMUT (Capacitive Micromachined Ultrasonic Transducer). CMUT can form a receiving surface with several tens to thousands of capacitive cells in several mm □, and because it uses a lightweight diaphragm, it can secure a wide receiving band. It has become.

  FIG. 3 is a schematic view of a CMUT element array formed on the semiconductor wafer 18. 7A to 7D are schematic diagrams illustrating an embodiment of the receiving surface 10.

  The CMUT element is determined by cutting the collective region of the vibrating membrane (membrane) from the semiconductor wafer 18 by a dicing cut or the like as a unit cell. The unit cell is a minimum unit of a channel for reading an electric signal based on the acoustic wave signal from the probe 321. In the dicing cut, a necessary device region is cut out by repeating parallel cutting at a predetermined interval. The CMUT element having the cut receiving surface 10 can be arranged in a predetermined shape and a predetermined size.

  Therefore, the outer edge of the reception surface 10 of the cut-out CMUT element is a substantially parallelogram having four apexes, as shown in FIGS. 3 and 7A. For the purpose of reducing the orientation dependency of the probe 321 when mounted on the probe array 32, that is, from the viewpoint of symmetry, the present embodiment has a square shape.

  As shown in FIG. 7A, the receiving surface 10 of this embodiment has 6 × 6 = 36 unit cells of CMUT elements. The CMUT element defines an electrostatic capacity and has an anode / cathode pair (not shown) for reading out a change in electrostatic capacity to the outside. A vibrating membrane (membrane) that receives acoustic waves is acoustically coupled to one of the anode-cathode pair. Therefore, the receiving surface 10 in the CMUT element can be determined as the shape of a vibrating membrane acoustically coupled to one of the anode-cathode pair.

  In the receiving surface 10 shown in FIG. 7A, the four tops Va are right angles, and the side Ea is a straight square. In addition, the receiving surface 10 of this embodiment includes unit cells 17 arranged in a matrix.

  On the other hand, the receiving surface 10 shown in FIG. 7B is different from the receiving surface 10 shown in FIG. 7A in that the four top portions Vb are subjected to a taper process of 45 degrees with respect to the side portions. . In the present embodiment, the length of the tapered portion is preferably 14% or less with respect to the side of the circumscribed square, which is the smallest parallelogram inscribed in the receiving surface 10 outside the receiving surface 10. .

  In addition, the receiving surface 10 shown in FIG. 7C has four points Vb that are R-processed in a quarter circle shape and that the unit cells 17 have a staggered arrangement. It differs from each of the receiving surfaces 10 shown in FIGS. 7 (a) and 7 (b). In the staggered arrangement of this embodiment, the unit cells 17 are 180 degrees out of phase for each column.

  Moreover, the receiving surface 10 shown in FIG.7 (d) is different from the receiving surface 10 shown in FIG.7 (c) in that the edge part Ed is prescribed | regulated by the curve.

  As described above, the receiving surfaces 10 are substantially perpendicular to each other as shown in FIGS. 1B to 1C as well as geometrically exact squares as shown in FIG. And may have a substantially square shape with adjacent sides having the same length.

  That is, in the present specification, the receiving surface 10 does not need to be a geometrically strict parallelogram, and as shown in FIGS. 7B to 7D, a simple semiconductor cutting process such as dicing cut is possible. A substantially parallel square defined by the processing of the peripheral edge is included. 7B and 7C, the taper processing and R processing for the top portions Vb and Vc of the receiving surface 10 are performed with the intention of reducing the occurrence of chipping, chipping, and the like occurring at the top portion in handling after cutting. Is called.

  The probe applicable to the probe array of the present invention includes a piezoelectric element type acoustic wave transducer (Piezoelectric Micromachined Ultrasonic Transducer) in addition to the CMUT.

<Supporting part>
Next, the support part 322 is demonstrated using FIG. 1, FIG. The support unit 322 supports the plurality of probes 321 along the opening provided in the support unit 322. The present embodiment is a probe array 32 in which a plurality of probes 321 are connected to a plurality of openings 40 provided in a hemispherical support portion 322, respectively.

  A plurality of probes are connected to the support portion 322 so that each receiving surface faces inside the bowl-shaped curved surface. The curved surface is preferably a rotating quadratic curved surface from the viewpoint of symmetry. In general, rotating quadric surfaces include cones, cylinders, parabolic columns, hyperbolic columns, elliptical columns, sinusoidal columns, parabolic columns, as well as spheres, hemispheres, elliptical spheres, rotating paraboloids, and rotating hyperboloids. . On the other hand, the rotating quadric surface in the present invention includes a sphere, a hemisphere, an elliptic sphere, a rotating paraboloid, and a rotating hyperboloid.

  In other words, the rotating quadric surface in the present invention is an aspect that satisfies the “non-developable surface requirement” and the “iso center requirement”.

  The non-developable surface requirement is a requirement that a parallelization problem occurs between adjacent reception surfaces when parallelogram reception surfaces are arranged, and corresponds to the problem of the present invention. The developable surface means a curved surface formed only by deformation without expanding and contracting a development drawing drawn on a plane, and the non-expandable surface is accompanied by partial expansion and contraction. Otherwise, it means a curved surface that is not formed in a development view drawn on a plane.

  In addition, the “iso center requirement” is a condition in which an effective reception area of a probe array including a plurality of probes overlaps at a specific one to form a high sensitivity area, and is a prerequisite for the present invention. This is a corresponding requirement. One specific place is called an iso center, and if the inner surface of the probe array is a hemisphere, the center of curvature of the hemisphere coincides with the iso center. Each of the rotating quadratic curved surfaces shown in FIG. 6 has an iso center.

  As shown in FIG. 5, the support portion 322 has an inner surface defined by a rotation quadratic curved surface 45 in which a virtual quadratic curve 41 is rotated around a virtual rotation axis 46. In the present embodiment, the virtual quadratic curve is a circle, and the inner surface of the support portion 322 is defined by a hemisphere. By using a rotating quadric surface, the acoustic wave propagating from the subject arranged at a position overlapping with the rotation axis direction 40 is transmitted to another structure around the probe array 32 whose inner surface is defined by the rotating quadratic surface. It is possible to receive an acoustic wave without being affected by reflection, attenuation, or the like. The rotation quadratic curved surface 45 in the present embodiment is a hemisphere.

  In FIG. 5, the matching liquid arranged between the subject 20 and the probe array 32 is omitted.

  The reception area of the reception surface 10 of each probe 321 is understood with the normal lines Ni and Ni + 1 in the figure as the center, and generality is not lost. As shown in FIG. 6, the probe 321 is connected to the support portion 322 so that the normal line Ni of the receiving surface 10 faces the inside of the rotation secondary curved surface 45 surrounding the rotation shaft 46. Yes. In the present embodiment, each normal line N of each receiving surface overlaps the center 45 c of the hemisphere of the rotating quadratic curved surface 45.

  In addition, the support part 322 has the opening part 16 in the direction which arrange | positions a test object. Further, the support portion vertex v <b> 1 is provided on the side farthest from the opening 16. The support portion 322 includes a plurality of openings 40, and the receiving surface 10 is substantially parallel to the tangential plane 15 of the rotating quadratic surface that intersects the corresponding openings 40. In the present embodiment, the angle formed by the receiving surface 10 and the tangential plane 15 is an angle within a range of ± 3 degrees.

  FIGS. 6A to 6D show a third embodiment relating to an aspect in which the virtual quadratic curve that is the basis of the rotating quadratic curved surface is a circle 41, an ellipse 42, a parabola 43, and a hyperbola 44, respectively. Has been.

  As shown in FIG. 6A, when the virtual quadratic curve is a circle 41, the virtual rotation axis 46 is set to match the diameter of the circle 41. As shown in FIG. 6B, when the virtual quadratic curve is an ellipse 42, the virtual rotation axis 46 is set to the major axis or minor axis of the ellipse. In the present embodiment, it coincides with the major axis of the ellipse 42. As shown in FIG. 6C, when the virtual quadratic curve is a parabola 43, the virtual rotation axis 46 is set as a virtual axis connecting the focal point f3 and the vertex v3 of the parabola 43. As shown in FIG. 6D, when the virtual quadratic curve is a hyperbola 44, the virtual rotation axis 46 is set as a virtual axis connecting the focal point f4 of the hyperbola 44 and the vertex v4.

  As shown in FIGS. 1B and 5, the opening 40 is formed in the support portion 322 in a shape that fits the receiving surface 10. The openings 40 in the present embodiment are substantially square having adjacent sides that are substantially perpendicular to each other and have the same length.

<Arrangement of receiving surface on rotating quadric surface of receiving surface>
Next, the arrangement of the receiving surface on the rotating quadric surface, which is a feature of the present invention, will be described with reference to FIG.

  1A to 1D and FIG. 5, a plurality of support portions 322 provided with a plurality of square openings 40, and a plurality of reception surfaces 10 and conversion elements 14 corresponding to the respective openings 40. A probe array 32 according to the first embodiment is shown.

  In order to understand the arrangement of the receiving surface 10 on the rotating quadric surface, one of the receiving surfaces to be considered will be considered as a representative. Such generalization can be applied to most parts of the receiving surface array excluding singular points such as the periphery of the receiving surface array.

  FIG.1 (c) is the elements on larger scale which explain the arrangement | sequence of a receiving surface in detail by expanding the part shown with the rectangle of the broken line of FIG.1 (d). FIG. 5 is a schematic cross-sectional view relating to the first embodiment, and shows the probe 321 connected to the opening 40 of the support portion 322 and the probe 321 in a disconnected state.

  The receiving surface 10 shown in FIGS. 1C, 1D, and 5 is a substantially parallelogram having four apexes, one apex (vr1) being the other three apexes (vr2, vr3). , Vr4) is closer to the virtual rotation axis 46. The virtual rotation shaft 46 passes through the support portion vertex v1 of the support portion 322 and is disposed parallel to the z axis.

  In the present embodiment, as shown in FIG. 7A, the receiving surface 10 has four sides sandwiched between two adjacent apexes. In FIG.1 (c), the receiving surface 10 has the side A to which its attention is paid. On the other hand, the adjacent receiving surface 19, which is one of the four adjacent receiving surfaces (♦ marks) surrounding the receiving surface 10 (marked by ○), has a side B on the receiving surface side. doing. The receiving surface 10 and the adjacent receiving surface 19 are adjacent to each other with a substantially parallel gap. Thereby, the overlap of the effective reception areas between the reception surface 10 and the adjacent reception surface is suppressed, and crosstalk between adjacent regions is suppressed. The gap portion is a portion of the support portion 322 sandwiched between the side portion A and the side portion B. Side A and side B that define the gap are substantially parallel to form an angle of 0 degrees to 10 degrees.

  By arranging the receiving surface as described above, the receiving surface 10 is arranged to be surrounded by four adjacent receiving surfaces that are adjacent to each other with a distance smaller than the fifth and subsequent distances from the other receiving surfaces. It is possible to reduce the distance between the adjacent receiving surface and the receiving surface 10 of interest to increase the mounting density of the probes 321 and to suppress crosstalk in the effective receiving area of the adjacent probes 321. It becomes.

  Further, by arranging in this way, the receiving surface 10 can take a spiral arrangement on the rotating quadratic curved surface at the position of the corresponding opening 40, and the cross in the effective receiving area of the adjacent probe 321 can be obtained. It is possible to suppress the talk and increase the mounting density of the probes 321 in the probe array 32.

  In the overhead view of FIG. 1A, the receiving surface 10 is spiral with respect to the support portion 322 whose inner surface is defined by a hemisphere obtained by rotating a quarter circle around the virtual rotation axis 46. Are arranged.

The spiral arrangement of the receiving surface is located at the intersection of two types of helical arrangements from the support portion vertex v1 side along the inner surface of the support portion 322 toward the opening of the support portion. (In the direction of z in FIG. 1A)
As shown in FIG. 1A, one spiral arrangement is an arrangement along a right-handed spiral straddling the virtual quadratic curve 41R, and the other spiral arrangement is a left-handed spiral straddling the virtual quadratic curve 41R. It is an arrangement along. In this manner, the number of probes 321 arranged increases from the support portion vertex V1 toward the periphery of the support portion 322 while ensuring the parallelism of the gap between the receiving surfaces. The arrangement of the probes 322 can be determined so as to increase from the support portion vertex V1 toward the periphery of the support portion 322 based on the Fibonacci number sequence or the Tribonacci number sequence, which is a modification of the Fibonacci number sequence.

  The virtual quadratic curve 41R coincides with a virtual quadratic curve defined by the intersection of the virtual plane 47 including the virtual rotation axis 46 and the support portion 322. In the present embodiment, the virtual quadratic curve 41R is a quarter circle. is there. Moreover, it can be said that the virtual quadratic curve 41R illustrated in FIG. 1A is one of a group of virtual quadratic curves serving as the basis of the rotating quadratic curved surface 45 (FIG. 5) that defines the inner surface of the support portion 322.

  In this manner, by arranging a plurality of substantially parallelogram-shaped receiving surfaces 10 on a plane on the support portion 322 having the inner surface of the rotating quadratic curved surface 45, a high mounting density on the support portion 322 of the probe 321 can be achieved. It can be realized.

  It can be said that this embodiment is an aspect described as follows.

  A probe array 32 having a bowl-shaped support portion 322 for supporting a plurality of probes 321, and the probe 321 has a substantially parallelogram receiving surface 10 for receiving acoustic waves.

  Further, the plurality of receiving surfaces 10 included in the predetermined region of the support portion 322 cross a plurality of clockwise virtual spirals CW along the inner surface from the side of the center V1 of the bowl-shaped inner surface of the support portion 322. Are arranged on a grid composed of intersections with a plurality of counterclockwise virtual spirals CCW.

  The predetermined area described above is an arbitrary area in which the receiving surface 10 is arranged in at least two directions that are not parallel to each other, and includes, for example, an area indicated by a broken-line rectangle in FIG.

  Therefore, the predetermined area described above is a form in which at least two receiving surfaces 10 adjacent in at least two arrangement directions are included.

  In addition, as a non bowl-shaped support part which is not the object of the present invention, there is a non-quadratic surface such as a cylinder or an elliptic cylinder. For example, in a cylindrical support part whose inner surface is defined by a cylinder, when arranging a substantially parallelogram receiving surface, there is no restriction on the geometry of the top part and the virtual rotation axis, and without taking a spiral arrangement, It is possible to take a form in which a receiving surface is mounted.

<Scanning trajectory of probe array>
The trajectory of the probe array in the optical ultrasonic measurement apparatus according to the second embodiment will be described with reference to FIG. The scanning trajectory of this embodiment is a spiral trajectory. The spiral trajectory is a scanning trajectory that moves so that the radial coordinate relative to the center of rotation changes in either an increase or a decrease.

  FIG. 4 is a diagram schematically representing an example of the movement of the spiral trajectory with the support portion vertex v1 of the probe array as a representative. The point O in FIG. 4 indicates the position of the support portion vertex v1 before the spiral scan and corresponds to the origin. Each black dot in FIG. 4 indicates the position of the support portion vertex v1 during photoacoustic wave measurement. The probe array moves while sequentially tracking the positions of the black spots. The point p is a certain point on the movement trajectory of the probe array. When the position coordinates (x, y) of the point p are expressed in the polar coordinate system, the equation (1) is obtained.

x = r (t) cosΦ
Y = r (t) sinΦ ... (Formula 1)
Here, r (t) is a radial coordinate (moving radius), and φ is an angle formed by the x-axis and a line from the origin to the point p. In the present embodiment, the probe array is moved so that the radial coordinate r (t) on the movement trajectory of the probe array changes to either increase or decrease. Further, the liquid tank scanning unit preferably moves the probe array so that the tangential speed of the movement trajectory is constant.

  Usually, the photoacoustic wave detection timing is determined by the repetition frequency of the pulsed light emitted from the light source. For example, when a light source having a repetition frequency of 10 Hz is used, a photoacoustic wave can be generated once every 0.1 second. Therefore, when the velocity in the tangential direction is constant, assuming that photoacoustic waves are detected every 0.1 seconds, sampling can be performed uniformly in space.

  Further, it is preferable that the liquid tank scanning unit moves the probe array from the outside of the moving plane in consideration of acceleration toward the origin. That is, if the acceleration at the initial stage of movement is large, the shaking of the entire apparatus becomes large, and the shaking may affect the measurement. Therefore, the movement of the liquid tank can be reduced by starting the movement from the outer periphery where the acceleration toward the origin is small and moving toward the inner periphery.

  Moreover, it is preferable that the liquid tank scanning unit performs continuous movement that moves continuously instead of the step-and-repeat method that repeats movement and stationary. Thereby, the time for which the liquid tank is scanned is also shortened. Moreover, since there is little change in the acceleration of movement, the undulation of the matching liquid stored in the liquid tank can be reduced.

DESCRIPTION OF SYMBOLS 10 Reception surface 14 Conversion element 32 Probe array 40 Aperture 41-44 Virtual quadratic curve 45 Rotation quadratic curved surface 46 Virtual rotation axis 321 Probe 322 Support part vr1-vr4 Top part

Claims (24)

A support portion having a bowl-shaped inner surface;
A probe array having a plurality of probes, each receiving surface being connected to be directed to the inside of the inner surface, and converting an acoustic wave into an electrical signal,
The inner surface is defined by a rotating quadratic curved surface obtained by rotating a virtual quadratic curve around a virtual rotation axis of the support portion.
The probe includes a substantially parallelogram-shaped receiving surface defined by four apexes, and a conversion element that converts an acoustic wave received on the receiving surface into an electric signal,
1. The probe array according to claim 1, wherein one of the four tops of the receiving surface is closer to the virtual rotation axis than the other three tops. When the virtual quadratic curve is a circle, the virtual rotation axis is the diameter of the circle;
When the virtual quadratic curve is an ellipse, the virtual rotation axis is the major axis or minor axis of the ellipse,
When the virtual quadratic curve is a parabola, the virtual rotation axis is a virtual axis connecting the focal point and the vertex of the parabola,
The probe array according to claim 1, wherein when the virtual quadratic curve is a hyperbola, the virtual rotation axis is a virtual axis connecting a focal point and a vertex of the hyperbola.   The reception area of the reception surface is connected to the support portion so as to face the inside of the rotation quadratic surface surrounding the virtual rotation axis around the axis. The transducer array described. The inner surface is provided with a plurality of acoustically opened openings,
4. The probe array according to claim 1, wherein the receiving surface is disposed in each of the plurality of openings. 5.   The probe array according to claim 4, wherein the receiving surface is substantially parallel to a tangent plane of the rotating quadric surface intersecting with the corresponding opening.   6. The probe array according to claim 1, wherein the substantially parallelograms are substantially squares having adjacent sides that are substantially perpendicular to each other and have the same length. 7. .   6. The probe array according to 4 or 5, wherein the opening is substantially square.   The reception surface is surrounded by four adjacent reception surfaces that are adjacent to each other at a distance smaller than the fifth and subsequent distances with respect to other reception surfaces. The probe array according to the item. Each of the reception surface and the adjacent reception surface has four sides sandwiched between two adjacent top portions of the four top portions,
The adjacent receiving surface and the receiving surface are adjacent to each other with a substantially parallel gap therebetween,
9. The probe array according to claim 8, wherein the gap portion forms an angle of not less than 0 degrees and not more than 10 degrees. When the intersection of the support part and the virtual rotation axis is the support part vertex,
Along each of the left-handed spiral and the right-handed spiral intersecting each other across a virtual quadratic curve defined by the intersection of the virtual plane including the virtual rotation axis and the support part,
The probe array according to claim 1, wherein the plurality of receiving surfaces are arranged on the support portion.   The probe includes at least one of a capacitive probe (Capacitive Micromachined Ultrasonic Transducer) and a piezoelectric device type probe (Piezoelectric Micromachined Ultrasonic Transducer). The probe array according to claim 1, wherein the probe array is provided. The probe array according to any one of claims 1 to 11,
An acoustic wave measuring device having a liquid tank in which the matching liquid is stored,
The liquid tank has an opening that is acoustically opened so that the subject can be brought into acoustic contact with the stored matching liquid.
The acoustic wave measuring device according to claim 1, wherein the probe array is connected to the liquid tank on a side facing the opening.   The acoustic wave measuring device according to claim 11, wherein the probe array is connected to the liquid tank so that the receiving surface of the probe faces the tank of the liquid tank.   The support base having a support surface on which the subject is supported and an insertion port that is provided on the support surface and into which the subject is inserted is provided on the side of the opening. Acoustic wave measuring device.   The acoustic wave measuring device according to claim 14, further comprising a liquid tank scanning unit that moves the liquid tank relative to the insertion port.   The acoustic wave measuring device according to claim 14, wherein the probe array includes a light irradiation unit that irradiates near-infrared light or infrared light toward the insertion port. A probe array having a bowl-shaped support for supporting a plurality of probes,
The probe has a substantially parallelogram receiving surface for receiving acoustic waves,
The plurality of receiving surfaces included in the predetermined region of the support part are a plurality of right-handed virtual spirals along the inner surface from the center side of the bowl-shaped inner surface of the support part, and a left-hand winding intersecting them. The probe array is characterized in that the plurality of probes are supported by the support portion so as to be arranged on a lattice formed by intersections with a plurality of virtual spirals.   The receiving surface has four apexes defining the substantially parallelogram, and one of the four apexes is closer to the center of the inner surface than the other three apexes. The probe array according to claim 17, characterized in that:   19. The probe array according to claim 17, wherein the substantially parallelograms are substantially squares having adjacent sides that are substantially perpendicular to each other and have the same length.   The probe array according to any one of claims 17 to 19, wherein the predetermined area is an area including at least four or more reception surfaces adjacent in at least two arrangement directions. The probe array according to any one of claims 17 to 20,
An acoustic wave measuring device having a liquid tank in which the matching liquid is stored,
The liquid tank has an opening that is acoustically opened so that the subject can be brought into acoustic contact with the stored matching liquid.
The acoustic wave measuring device according to claim 1, wherein the probe array is connected to the liquid tank on a side facing the opening.   The sound according to claim 21, further comprising a support base having a support surface on which the subject is supported and an insertion port provided on the support surface and into which the subject is inserted. Wave measuring device.   The acoustic wave measuring apparatus according to claim 22, further comprising a liquid tank scanning unit that moves the liquid tank relative to the insertion port.   The acoustic wave measuring device according to claim 22 or 23, wherein the probe array includes a light irradiation unit that irradiates near-infrared light or infrared light toward the insertion port.

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