JP2012168092A - Photoacoustic imaging device, probe unit used in the same, and operation method of photoacoustic imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate position matching of a plurality of branched light and a plurality of optical fibers in photoacoustic imaging implemented by using the plurality of optical fibers and guiding laser beams.SOLUTION: A photoacoustic imaging device includes a light branching section 12 having a branch DOE 40 for branching one and another of two laser beams Lx and Ly respectively incident at different positions to a plurality of first branched beams Lxd and a plurality of second branched beams Lyd respectively according to a branching pattern; a first bundle fiber 14x including a plurality of first optical fibers 13x in which one end faces 13e thereof are arrayed while matching the branching pattern; and a second bundle fiber 14y including a plurality of second optical fibers 13y in which one end faces 14e thereof are arrayed while matching the branching pattern. The first plurality of branched beams Lxd are guided by the plurality of first optical fibers 13x, and the second plurality of branched beams Lyd are guided by the plurality of second optical fibers 13y.

Description

  The present invention relates to a photoacoustic imaging device that generates a photoacoustic image by detecting a photoacoustic wave generated in a subject by irradiating the subject with light, and a probe unit used therefor and an operation of the photoacoustic imaging device It is about the method.

  Conventionally, as a method for acquiring a tomographic image inside a subject, an ultrasonic image is generated by detecting ultrasonic waves reflected in the subject by irradiating the subject with ultrasonic waves. Ultrasonic imaging for obtaining a morphological tomographic image is known. On the other hand, in the examination of a subject, development of an apparatus that displays not only a morphological tomographic image but also a functional tomographic image has been advanced in recent years. One of such devices is a device using a photoacoustic analysis method. This photoacoustic analysis method irradiates a subject with light having a predetermined wavelength (for example, visible light, near infrared light, or mid infrared light), and a specific substance in the subject absorbs the energy of this light. A photoacoustic wave, which is the resulting elastic wave, is detected and the concentration of the specific substance is quantitatively measured. The specific substance in the subject is, for example, glucose or hemoglobin contained in blood. A technique for detecting a photoacoustic wave and generating a photoacoustic image based on the detection signal is called photoacoustic imaging (PAI) or photoacoustic tomography.

  Conventionally, there are the following problems in photoacoustic imaging using the photoacoustic effect as described above. The intensity of light applied to the subject is significantly attenuated by absorption and scattering in the process of propagating through the subject. Further, the intensity of the photoacoustic wave generated in the subject based on the irradiated light is also attenuated by absorption and scattering in the process of propagating in the subject. Therefore, in photoacoustic imaging, it is difficult to obtain information on the deep part of the subject. In order to solve this problem, for example, it is conceivable to increase the generated photoacoustic wave by increasing the amount of energy of light irradiated into the subject.

  However, it is difficult to guide high-energy (1 mJ or more) pulsed laser light required in photoacoustic imaging using a single optical fiber. This is because the end face of the optical fiber is likely to be destroyed. Therefore, it is preferable that the pulsed laser beam can be branched and guided by a plurality of optical fibers.

  Moreover, in a photoacoustic imaging apparatus using photoacoustic imaging, a probe unit in which an optical system and an ultrasonic detection probe are combined together is used. Accordingly, the cord portion of the probe unit is required to be flexible from the viewpoint of user handling performance.

  Thus, for example, Patent Document 1 discloses a method of guiding pulsed laser light to the tip of a probe unit using a bundle fiber in which a large number of thin silica optical fibers having a core and cladding structure (core / cladding structure) are bundled. Has been. However, a specific method for making the pulse laser beam incident on each of the optical fibers in the bundle fiber is not disclosed.

  On the other hand, as a method for generating a plurality of branched light beams to be incident on a plurality of optical fibers, for example, Patent Document 2 discloses a method of splitting one laser beam n times using n-1 beam splitters, and diffraction. A method of branching one laser beam into a plurality of beams using an optical element (DOE: Diffractive Optical Elements) is disclosed.

JP 2010-12295 A JP 2005-308967 A

  However, in the former method in Patent Document 2, in order to obtain a large number (for example, 16 or more) of laser beams, a large number (for example, 15 or more) of beam splitters are necessary, and the arrangement of the optical system is complicated. However, there is a problem that the apparatus becomes large, and there is a problem that each of the plurality of branched lights and each of the plurality of optical fibers must be separately aligned. On the other hand, in the latter method in Patent Document 2, although it is possible to branch the laser beam at once using a diffractive optical element, each of the plurality of branched lights and each of the plurality of optical fibers are positioned separately. There is no change in the points that must be matched. The operation of individually aligning each of the plurality of branched lights and each of the plurality of optical fibers is very complicated.

  The present invention has been made in view of the above problems, and in photoacoustic imaging performed by guiding laser light using a plurality of optical fibers, each of the plurality of branched lights and each of the plurality of optical fibers are provided. It is an object of the present invention to provide a photoacoustic imaging apparatus that can facilitate alignment, a probe unit used therefor, and a method for operating the photoacoustic imaging apparatus.

A light irradiating unit that irradiates measurement light into the subject, an electroacoustic conversion unit that detects a photoacoustic wave generated in the subject by irradiation of the measuring light and converts the photoacoustic wave into an electrical signal, and an electrical signal In a photoacoustic imaging device comprising an image generation unit that generates a photoacoustic image based on
One branch diffraction in which one and the other of two laser beams incident on different positions from the upstream side of the optical system are branched as a first plurality of branched lights and a second plurality of branched lights, respectively, according to a predetermined branch pattern An optical branch having an optical element;
A first bundle fiber including a first plurality of optical fibers having a core / cladding structure, wherein one end face of the first plurality of optical fibers on one end face of the first bundle fiber has a branch pattern Correspondingly arranged first bundle fibers;
A second bundle fiber including a second plurality of optical fibers having a core / cladding structure, wherein one end face of the second plurality of optical fibers on one end face of the second bundle fiber has a branch pattern A second bundle fiber arranged correspondingly,
The first bundle fiber causes each of the first plurality of branched lights to enter each of the cores of the first plurality of optical fibers from the one end face of the first bundle fiber, and the first plurality of lights. The first plurality of branched lights incident on the core of the fiber are arranged so as to be guided to the light irradiation unit connected to the other end face of the first bundle fiber,
The second bundle fiber causes each of the second plurality of branched lights to enter each of the second plurality of optical fiber cores from the one end face of the second bundle fiber, and the second plurality of lights. The second plurality of branched lights incident on the core of the fiber are arranged so as to be guided to the light irradiation unit connected to the other end face of the second bundle fiber,
The light irradiation unit irradiates the first plurality of branched lights and the second plurality of branched lights as measurement lights.

  In this specification, the “branch pattern” means a pattern of bright spots on a virtual plane perpendicular to the traveling direction of the laser beam before branching about the laser beam (branching light) branched by the branching diffractive optical element. To do. In such a branch pattern, since the branched laser beam has a divergence angle, the scale of the pattern varies depending on the position of the virtual plane. Therefore, in general, a pattern obtained by removing the scale information from a pattern including such scale information (including an array pattern described later) and standardizing the pattern (for example, the length between the two most distant points is 1) is used. This is called the “standard pattern” of the pattern.

  One end face of the plurality of optical fibers is “arranged corresponding to the branch pattern” means that the standard pattern of the end face array pattern substantially matches the standard pattern of the branch pattern. It means that the end faces are arranged in the same plane. The “array pattern” of the end faces means an array pattern of representative points (for example, the centers of the end faces) related to one end face of a plurality of optical fibers. The two patterns “substantially match” means that even if these patterns are different, each of the plurality of branched lights can enter each of the cores of the plurality of optical fibers. This means that it is handled as a match.

  In the photoacoustic imaging device according to the present invention, the positional relationship between the one end surface of the first bundle fiber and the light branching portion, and the positional relationship between the one end surface of the second bundle fiber and the light branching portion. It is preferable that a position adjusting unit for adjusting the position is provided.

In the photoacoustic imaging device according to the present invention, the light branching unit has a first condenser lens system and a second condenser lens system on the downstream side of the optical system of the branching diffractive optical element,
The first condenser lens system is arranged such that the focal point of the first condenser lens system corresponds to the incident position of the one laser beam in the branching diffractive optical element,
The second condenser lens system is preferably arranged so that the focal point of the second condenser lens system corresponds to the incident position of the other laser beam in the branch diffractive optical element.

  In the photoacoustic imaging apparatus according to the present invention, the light branching unit adjusts the position of the first condenser lens system in the optical axis direction and the lens position adjustment for adjusting the position of the second condenser lens system in the optical axis direction. It is preferable to have a part.

  In the photoacoustic imaging apparatus according to the present invention, the optical branching unit preferably has a homogenizer optical element corresponding to each of the optical paths of the two laser beams on the upstream side of the optical system of the branching diffractive optical element. .

  In the photoacoustic imaging device according to the present invention, the optical branching unit may have a holographic diffusion plate corresponding to each of the optical paths of the two laser beams on the downstream side of the optical system of the branching diffractive optical element. preferable.

  In the photoacoustic imaging apparatus according to the present invention, the optical branching unit may have a variable beam expander corresponding to each of the optical paths of the two laser beams on the upstream side of the optical system of the branching diffractive optical element. preferable.

And in the photoacoustic imaging device according to the present invention, the branch pattern has a hexagonal structure,
It is preferable that the one end face of each of the first plurality of optical fibers and the second plurality of optical fibers is arranged in a close-packed structure.

In the photoacoustic imaging apparatus according to the present invention, the one end face of the first bundle fiber has a first reflective mask on the end face so that the cores of the first plurality of optical fibers on the end face are exposed. Have
The one end face of the second bundle fiber preferably has a second reflection mask on the end face so that the cores of the second plurality of optical fibers on the end face are exposed.

And in the photoacoustic imaging device according to the present invention, the light irradiation part is the other end face of the first plurality of optical fibers and the other end face of the second plurality of optical fibers,
The other end face is preferably arranged in a line at intervals.

And in the photoacoustic imaging device according to the present invention, the light irradiation part is a light guide plate having a tapered shape,
It is preferable that the other end face of the first bundle fiber and the other end face of the second bundle fiber are connected to the end face on the short side of the light guide plate in a detachable state.

Furthermore, the probe unit according to the present invention is:
Light that irradiates the subject with measurement light, detects photoacoustic waves generated in the subject due to measurement light irradiation, converts the photoacoustic waves into electrical signals, and generates a photoacoustic image based on the electrical signals In a probe unit used in an acoustic imaging device,
A light irradiator for irradiating measurement light into the subject;
An electroacoustic conversion unit that detects a photoacoustic wave generated in the subject by irradiation of measurement light and converts the photoacoustic wave into an electrical signal;
One branch diffraction in which one and the other of two laser beams incident on different positions from the upstream side of the optical system are branched as a first plurality of branched lights and a second plurality of branched lights, respectively, according to a predetermined branch pattern An optical branch having an optical element;
A first bundle fiber including a first plurality of optical fibers having a core / cladding structure, wherein one end face of the first plurality of optical fibers on one end face of the first bundle fiber has a branch pattern Correspondingly arranged first bundle fibers;
A second bundle fiber including a second plurality of optical fibers having a core / cladding structure, wherein one end face of the second plurality of optical fibers on one end face of the second bundle fiber has a branch pattern A second bundle fiber arranged correspondingly,
The first bundle fiber causes each of the first plurality of branched lights to enter each of the cores of the first plurality of optical fibers from the one end face of the first bundle fiber, and the first plurality of lights. The first plurality of branched lights incident on the core of the fiber are arranged so as to be guided to the light irradiation unit connected at the other end face of the first bundle fiber,
The second bundle fiber causes each of the second plurality of branched lights to enter each of the second plurality of optical fiber cores from the one end face of the second bundle fiber, and the second plurality of lights. The second plurality of branched lights incident on the core of the fiber are arranged so as to be guided to a light irradiation unit connected to the other end face of the second bundle fiber,
The light irradiation unit irradiates the first plurality of branched lights and the second plurality of branched lights as measurement lights.

Furthermore, the operation method of the photoacoustic imaging device according to the present invention is as follows.
Light that irradiates the subject with measurement light, detects photoacoustic waves generated in the subject due to measurement light irradiation, converts the photoacoustic waves into electrical signals, and generates a photoacoustic image based on the electrical signals In the operation method of the acoustic imaging apparatus,
One and the other of the two laser beams incident on different positions on the branch diffractive optical element from the upstream side of the optical system are respectively converted into a first plurality of branch lights according to a predetermined branch pattern defined by the branch diffractive optical element. And branching as a second plurality of branched lights,
A first bundle fiber including a first plurality of optical fibers having a core / cladding structure, wherein one end face of the first plurality of optical fibers on one end face of the first bundle fiber has a branch pattern Correspondingly arranged first bundle fibers;
A second bundle fiber including a second plurality of optical fibers having a core / cladding structure, wherein one end face of the second plurality of optical fibers on one end face of the second bundle fiber has a branch pattern Using a correspondingly bundled second bundle fiber,
Causing each of the first plurality of branched lights to enter each of the cores of the first plurality of optical fibers from the one end face of the first bundle fiber;
Guiding the first plurality of branched lights incident on the cores of the first plurality of optical fibers to the light irradiation unit;
Allowing each of the second plurality of branched lights to enter each of the cores of the second plurality of optical fibers from the one end face of the second bundle fiber;
Guiding the second plurality of branched lights incident on the cores of the second plurality of optical fibers to the light irradiation unit;
The first plurality of branched lights and the second plurality of branched lights guided to the light irradiation unit are irradiated as measurement lights.

  In particular, the photoacoustic imaging device and the probe unit according to the present invention are configured such that one of the two laser beams incident on different positions from the upstream side of the optical system and the other one of the first plurality of branched lights in accordance with a predetermined branch pattern. And a first bundle fiber including an optical branching unit having one branching diffractive optical element for branching as the second plurality of branched lights, and a first plurality of optical fibers having a core / cladding structure, A first bundle fiber in which one end face of the first plurality of optical fibers on one end face of one bundle fiber is arranged corresponding to the branch pattern, and a second plurality of optical fibers having a core / cladding structure. A second bundle fiber including one end face of the second plurality of optical fibers at one end face of the second bundle fiber. A second bundle fiber arranged corresponding to the first bundle, and the first bundle fiber sends each of the first plurality of branched lights to each of the cores of the first plurality of optical fibers. The first plurality of branched lights incident from the one end surface of the fiber and incident on the core of the first plurality of optical fibers are guided to the light irradiation unit connected to the other end surface of the first bundle fiber. The second bundle fiber is arranged so as to emit light, and each of the second plurality of branched lights is sent to each of the cores of the second plurality of optical fibers. The second plurality of branched lights incident on the core of the second plurality of optical fibers are guided so as to be guided to the light irradiation unit connected on the other end face of the second bundle fiber. Characterized in that the those. Therefore, by using the bundle fiber in which one end face of the plurality of optical fibers is arranged corresponding to the branching pattern, the alignment of each of the plurality of branched lights and each of the plurality of optical fibers can be performed collectively. it can. As a result, in photoacoustic imaging performed by guiding laser light using a plurality of optical fibers, it is easy to align each of the plurality of branched lights and each of the plurality of optical fibers.

  In addition, the operation method of the photoacoustic imaging apparatus according to the present invention is the branch diffractive optical element, in particular, for one and the other of the two laser beams incident on different positions on the branch diffractive optical element from the upstream side of the optical system. The first bundle fiber includes a first plurality of optical fibers each having a core / cladding structure that is branched as a first plurality of branched lights and a second plurality of branched lights, respectively, according to a predetermined branch pattern defined by A first bundle fiber in which one end face of the first plurality of optical fibers on one end face of the first bundle fiber is arranged corresponding to the branch pattern, and a second having a core / cladding structure. A second bundle fiber including a plurality of optical fibers, wherein one end face of the second plurality of optical fibers on one end face of the second bundle fiber is A second bundle fiber arranged in correspondence with the bifurcated pattern, and each of the first plurality of branched lights is sent to each of the cores of the first plurality of optical fibers from the one end face of the first bundle fiber. The second plurality of branched lights are operated so as to enter each of the second plurality of optical fiber cores from the one end face of the second bundle fiber. Therefore, by using the bundle fiber in which one end face of the plurality of optical fibers is arranged corresponding to the branching pattern, the alignment of each of the plurality of branched lights and each of the plurality of optical fibers can be performed collectively. it can. As a result, in photoacoustic imaging performed by guiding laser light using a plurality of optical fibers, it is easy to align each of the plurality of branched lights and each of the plurality of optical fibers.

It is the schematic which shows the structure of one Embodiment of the photoacoustic imaging device of this invention. It is a block diagram which shows the structure of the image generation part in FIG. It is a schematic sectional drawing which shows the structure of one Embodiment of the optical branching part and bundle fiber of this invention. It is the schematic which shows the example of the arrangement | sequence of the end surface of the some optical fiber in the incident end surface of a bundle fiber. It is a schematic sectional drawing which shows the example of a structure of the optical system which can adjust the scale of the branch pattern of several branch light. It is the schematic which shows the reflective mask provided in the incident end surface of bundle fiber. It is a schematic sectional drawing which shows a structure when the optical branching part further has the position adjustment part which adjusts the positional relationship of a light branching part and bundle fiber in FIG. It is a schematic sectional drawing which shows a structure when the light branching part further provided with the homogenizer optical element in FIG. It is a schematic sectional drawing which shows a structure when the optical branching part further provided with the holographic diffusion plate in FIG. It is a schematic sectional drawing which shows a structure when the optical branching part is further equipped with the variable beam expander in FIG. It is a schematic sectional drawing which shows the structural example for injecting two laser beams into an optical branching part. It is a schematic sectional drawing which shows the other structural example for injecting two laser beams into an optical branching part. It is the schematic which shows the structure of the front-end | tip part of the probe unit of this invention. It is the schematic which shows the other structure of the front-end | tip part of the probe unit of this invention.

  Hereinafter, although an embodiment of the present invention is described using a drawing, the present invention is not limited to this. In addition, for easy visual recognition, the scale of each component in the drawings is appropriately changed from the actual one.

“Embodiments of Photoacoustic Imaging Device, Probe Unit, and Photoacoustic Imaging Device Operation Method”
An embodiment of the photoacoustic imaging apparatus 10 of the present invention will be described. FIG. 1 is a schematic diagram illustrating the overall configuration of the photoacoustic imaging apparatus 10 according to the present embodiment. FIG. 2 is a block diagram illustrating a configuration of the image generation unit 2 of FIG. FIG. 3 is a schematic sectional view showing the configuration of an embodiment of the optical branching section 12 and the bundle fiber 14 of the present invention.

  The photoacoustic imaging apparatus 10 according to the present embodiment generates a measurement light L including a specific wavelength component and irradiates the subject 7 with the measurement light L, and the measurement light L is irradiated to the subject 7. An image generation unit 2 that detects photoacoustic waves U generated in the subject 7 to generate photoacoustic image data of an arbitrary cross section, an electroacoustic conversion unit 3 that converts an acoustic signal and an electrical signal, A display unit 6 for displaying the photoacoustic image data, an operation unit 5 for an operator to input patient information and imaging conditions of the apparatus, and a system control unit 4 for comprehensively controlling these units. .

  The probe unit 70 of the present embodiment includes the electroacoustic conversion unit 3, the light branching unit 12, the bundle fibers 14x and 14y, and the light irradiation unit 15.

  The method of operating the photoacoustic imaging apparatus of the present invention irradiates the subject 7 with the measurement light L, detects the photoacoustic wave U generated in the subject 7 by the irradiation of the measurement light L, and detects the photoacoustic wave. In the operation method of the photoacoustic imaging apparatus 10 that converts U into an electrical signal and generates a photoacoustic image based on the electrical signal, two light beams incident on different positions on the branching diffractive optical element 40 from the upstream side of the optical system. One and the other of the laser beams Lx and Ly are branched into a first plurality of branched beams Lxd and a second plurality of branched beams Lyd according to a predetermined branch pattern defined by the branch diffractive optical element 40, respectively. 1st bundle fiber 14x including the 1st some optical fiber 13x which has a clad structure, Comprising: 1st some light in one end surface 14e of the 1st bundle fiber 14x A second bundle fiber 14y including a first bundle fiber 14x in which one end face 13e of the fiber 13x is arranged corresponding to the branch pattern and a second plurality of optical fibers 13y having a core / clad structure; The second bundle fiber 14y in which the one end face 13e of the second plurality of optical fibers 13y on the one end face 14e of the second bundle fiber 14y is arranged corresponding to the branch pattern, Each of the branched lights Lxd is caused to enter each of the cores of the first plurality of optical fibers 13x from the one end face 14e of the first bundle fiber 14x, and is incident on the cores of the first plurality of optical fibers 13x. The plurality of branched lights Lxd are guided to the light irradiation unit 15, and each of the second plurality of branched lights Lyd is supplied to the second plurality of optical fibers. Each of the 3y cores is incident from the one end face 14e of the second bundle fiber 14y, and the second plurality of branched lights Lyd incident on the cores of the second plurality of optical fibers 13y are guided to the light irradiation unit 15. The photoacoustic imaging device 10 that emits light and emits the first plurality of branched lights Lxd and the second plurality of branched lights Lyd guided to the light irradiation unit 15 as the measurement light L is operated.

  The optical transmission unit 1 includes a light source unit 11 including a plurality of light sources having different wavelengths, a light branching unit 12 that branches the laser light Lo output from the light source unit 11 as a plurality of branched lights Ld, and a plurality of branched lights Ld. A bundle fiber 14 that guides light to the light irradiation unit 15 and a light irradiation unit 15 that irradiates the body surface of the subject 7 with the measurement light L are provided.

The light source unit 11 includes, for example, one or more light sources that generate light having a predetermined wavelength. As the light source, a light emitting element such as a semiconductor laser (LD), a solid-state laser, or a gas laser that generates a specific wavelength component or monochromatic light including the component can be used. The two laser beams Lx and Ly incident on different positions on the branching diffractive optical element 40 may have the same wavelength or different wavelengths. The light source unit 11 preferably outputs pulsed light having a pulse width of 1 to 100 nsec as laser light. The wavelength of the laser light is appropriately determined according to the light absorption characteristics of the substance in the subject to be measured. Although hemoglobin in a living body has different optical absorption characteristics depending on its state (oxygenated hemoglobin, reduced hemoglobin, methemoglobin, carbon dioxide hemoglobin, etc.), it generally absorbs light of 600 nm to 1000 nm. Therefore, for example, when the measurement target is hemoglobin in a living body (that is, when a blood vessel is imaged), it is generally preferable to set the thickness to about 600 to 1000 nm. Furthermore, from the viewpoint of reaching the deep part of the subject 7, the wavelength of the laser light is preferably 700 to 1000 nm. The output of the laser beam is 10 μJ / cm ² to several tens of mJ / cm ² from the viewpoints of propagation loss of laser beam and photoacoustic wave, efficiency of photoacoustic conversion, detection sensitivity of the current detector, and the like. Is preferred. Further, the repetition of the pulsed light output is preferably 10 Hz or more from the viewpoint of the image construction speed. Further, the laser beam may be a pulse train in which a plurality of the above pulsed beams are arranged.

  More specifically, for example, when the hemoglobin concentration of the subject 7 is measured, an Nd: YAG laser (emission wavelength: about 1000 nm) which is a kind of solid-state laser, or a He—Ne gas laser (emission light) which is a kind of gas laser. A laser beam having a pulse width of about 10 nsec is formed using a wavelength of 633 nm. When using a small light emitting element such as an LD, a material such as InGaAlP (emission wavelength: 550 to 650 nm), GaAlAs (emission wavelength: 650 to 900 nm), InGaAs or InGaAsP (emission wavelength: 900 to 2300 nm) is used. Can be used. Recently, a light-emitting element using InGaN that emits light with a wavelength of 550 nm or less is becoming available. Furthermore, an OPO (Optical Parametrical Oscillators) laser using a nonlinear optical crystal whose wavelength is variable can be used.

  The light branching unit 12 branches the two laser beams Lx and Ly output from the light source unit 11 using the branching diffractive optical element 40 (branching DOE). In this specification, the branched DOE means an optical element that generates a plurality of branched lights having different traveling directions by utilizing a light diffraction phenomenon. The number of branches is not particularly limited, but it is preferable to branch to 16 or more from the viewpoint of effectively dispersing the energy of the laser beam. In the present embodiment, the light branching unit 12 includes a branching DOE 40 and condenser lens systems 44x and 44y. Predetermined processing is performed at two locations where the laser light on the front surface (back surface as viewed from the laser incident side) of the branch DOE 40 is emitted, and a predetermined branch pattern is defined by the content of the processing. The branch pattern is not particularly limited, but is preferably a square structure or a hexagonal structure, and more preferably a hexagonal structure, from the viewpoint of reducing aberrations in the condenser lens system.

  The condensing lens system 44x makes it easy for a plurality of branch lights Lxd generated by the branch DOE 40 to enter the bundle fiber 14x, and facilitates alignment of each of the plurality of branch lights Lxd with the bundle fiber 14x. A plurality of branched lights Lxd are collimated. The condensing lens system 44x is arranged so that the focal point thereof corresponds to the incident position of the laser light Lx on the branch DOE 40. “The focus of the condensing lens system corresponds to the incident position” of the laser light in the branch DOE means that the focus of the condensing lens system is a predetermined part of the branch DOE and the laser light is incident as the branched light. It means that the light is included in a portion through which it can pass before it is emitted. In general, the focusing lens system is generally focused on the beam center of the exit surface. Further, when the light branching portion 12 has a condensing lens system 44x, the light branching portion 12 is a lens that moves the condensing lens system 44x in the optical axis direction in order to enable fine adjustment of the condensing lens system 44x. It is preferable to have a position adjustment unit. The condensing lens system 44x may be composed of one condensing lens, or may be a combined lens composed of two or more condensing lenses. The condensing lens system 44y is the same as that of the condensing lens system 44x in relation to the branch DOE 40 and the bundle fiber 14y. Further, when the wavelengths of the laser beam Lx and the laser beam Ly are different, the scale of the branch pattern is different even when the same branch DOE 40 is used, and therefore the position of the condensing lens system needs to be adjusted appropriately. In addition, it is preferable that the condensing lens system 44x arrange | positions the front side focus of the condensing lens system 44x according to the branch light emission position of branch DOE40, and arrange | positions a back side focal plane to the end surface 14e of bundle fiber 14x.

  The bundle fibers 14x and 14y guide the laser beams Lx and Ly branched by the light branching unit 12 to the light irradiation unit 15, respectively. Since the bundle fiber 14y is the same as the bundle fiber 14x because of the relationship between the condensing lens system 44y and the plurality of branched lights Lyd, the bundle fiber 14x will be described below as a representative. The bundle fiber 14x includes a plurality of optical fibers 13x having a core 13a and a clad 13b. The optical fiber 13x is not particularly limited, but is preferably a quartz fiber. The plurality of optical fibers 13x are arranged corresponding to a predetermined branch pattern defined by the branch DOE 40 from the viewpoint of efficiently guiding the plurality of branch lights Lxd. The arrangement pattern of the end faces 13e of the plurality of optical fibers 13x on the incident end face 14e of the bundle fiber 14x is a square structure from the viewpoint of ease of arrangement in the bundle fiber 14x and reduction of aberrations in the condenser lens system 44x. Alternatively, a hexagonal structure is preferable, and a hexagonal structure is more preferable. The end faces 13e of the plurality of optical fibers 13x are particularly preferably arranged in a close-packed structure. This is for the following reason. FIG. 4 is a conceptual diagram showing an example of the arrangement of the end faces 13e of the plurality of optical fibers 13x on the incident end face 14e of the bundle fiber 14x. 4a shows a case where the arrangement of the end faces 13e of the 64 optical fibers 13x has a square structure, and FIG. 4b shows a case where the arrangement of the end faces 13e of the 61 optical fibers 13x has a close-packed structure. Thus, consider the case where the same number of optical fibers 13x are arranged in a square structure and the case where they are arranged in a close-packed structure. At this time, when the distances from the center of the array pattern to the end face of the optical fiber farthest (W1 and W2 in FIG. 4) are compared with each other, the distance W2 of the close-packed structure is greater than the distance of the square structure. It turns out that it becomes shorter than W1. As the distance becomes longer, the spread angle of the branched light is set so as to increase accordingly, and thus the aberration of the condenser lens system increases. As a result, the accuracy of alignment between each of the plurality of branched lights Lxd and each of the plurality of optical fibers 13x decreases. Therefore, the arrangement of the end faces 13e of the plurality of optical fibers 13x on the incident end face 14e of the bundle fiber 14x is particularly preferably a close-packed structure.

  In addition to the above viewpoint, when it is particularly important to increase the alignment accuracy of the plurality of optical fibers 13x in the bundle fiber 14x, the lines may be divided and arranged for each line using a V-groove substrate. By arranging each line with reference to a glass or metal surface processed with a V-groove with high accuracy, the arrangement accuracy of the plurality of optical fibers 13x can be further increased. In such a case, the branch DOE 40 is designed according to the line arrangement of the plurality of optical fibers 13x.

  When each of the plurality of branched lights Lxd is actually incident on each of the cores 13a of the plurality of optical fibers 13x, the branch pattern of the branched light Lxd and the arrangement pattern of the end face 13e of the optical fiber 13x are substantially matched. is required. That is, it is necessary to substantially match not only the standard patterns of the branch pattern and the array pattern but also these patterns including the scale. Therefore, it is preferable that the optical system is set so that adjustment for substantially matching these patterns can be performed by configuring the condensing lens system as follows.

FIG. 5 is a schematic cross-sectional view showing an example of the configuration of an optical system that can adjust the scale of the branch pattern of a plurality of branch lights. A pattern interval y (interval between adjacent bright spots on a virtual plane passing through the focus and perpendicular to the optical axis) on the focal plane of the plurality of branched lights Ld generated from the branched DOE 90 is between the branched DOE 90 and the bundle fiber 94. There is a property proportional to the focal length of the condensing lens system. For example, as shown in FIG. 5, consider a case where the condensing lens system between the branching DOE 90 and the bundle fiber 94 is a coupled lens composed of a condensing lens 91 and a condensing lens 92. Focal length of the condenser lens 91 is f _2, the focal length of the condenser lens 92 is f _1, the distance of the condenser lens 91 and the condenser lens 92 is d, the synthesis of the binding system lens The focal length f is given by f = f ₁ · f ₂ / (f ₁ + f ₂ −d). Further, the distance s ″ from the reference surface P to the second main surface H ₂ ″ of the condenser lens 91 is given by s ″ = f ₂ (f ₁ −d) / (f ₁ + f ₂ −d). Specifically, the distance d means the distance from the first main surface H ₂ of the condensing lens 91 to the second main surface H ₁ ″ of the condensing lens 92, and the reference surface P is the surface of the branch DOE 90 on the lens side. That is, it means the exit surface of a plurality of branched lights. The combined focal length f of the coupling system lens means a distance from the reference plane P to the first main surface H of the coupling system lens.

  From the above equation, it can be seen that when the distance d changes, the combined focal length f and the distance s ″ also change. That is, the distance d is adjusted by moving the lens position adjusting unit 91a and / or 92a in the optical axis direction. Thus, the combined focal length f of the coupled lens can be adjusted, and as a result, the pattern interval y on the focal plane of the plurality of branched lights Ld, that is, the scale of the branched pattern can be adjusted. For other coupling lenses, the scale of the branching pattern can be adjusted by adjusting the synthetic focal length, which differs depending on the elements constituting the coupling lens. It is easy for a person skilled in the art to obtain the value by a known method. Branched light emitting position of DOE90 (reference plane P), it is preferable to place together rear synthesis focus on the end face of the bundle fiber 94.

  In the bundle fiber 14x, the one end face 14e of the bundle fiber 14x preferably has a reflective mask M on the end face 14e so that the core 13a on the end face 14e is exposed as shown in FIG. The bundle fiber 14x is usually manufactured by fixing the gaps between the plurality of optical fibers 13x with an adhesive. However, the adhesive has lower durability against laser light than optical fiber materials such as quartz. Therefore, the reflection mask M as described above can prevent the laser light from being irradiated to the region excluding the region of the core 13a where the plurality of branched lights Lxd are respectively incident. Such a reflective mask M is formed by, for example, depositing a dielectric multilayer film on a thin glass plate that has been drilled in accordance with the arrangement pattern of the cores 13a, and then the glass 13 so that the cores 13a and the holes are matched with each other. It is possible to form the plate by sticking it to the one end face 14e of the bundle fiber 14x.

  In the present embodiment, the light irradiation unit 15 includes a plurality of emission end faces 13e of the plurality of optical fibers 13x and 13y. The plurality of emission end faces 13e of the plurality of optical fibers 13x and 13y constituting the light irradiation unit 15 are arranged along the periphery of the electroacoustic conversion unit 3, for example. Moreover, when the some conversion element 54 which comprises the electroacoustic conversion part 3 is a transparent material, you may arrange | position the light irradiation part 15 so that the whole conversion element can be irradiated from the upper direction of the conversion element 54. FIG. The plurality of emission end faces 13e of the plurality of optical fibers 13x and 13y together with the plurality of conversion elements 54 constituting the electroacoustic conversion unit 3 form a plane, a convex surface, or a concave surface. Here, it is a plane.

  The electroacoustic conversion unit 3 includes a plurality of minute conversion elements 54 arranged in a one-dimensional or two-dimensional manner, for example. The conversion element 54 is a piezoelectric element made of a polymer film such as piezoelectric ceramics or polyvinylidene fluoride (PVDF). The electroacoustic conversion unit 3 receives the photoacoustic wave U generated in the subject by the light irradiation from the light irradiation unit 15. The conversion element 54 has a function of converting the photoacoustic wave U into an electric signal at the time of reception. The electroacoustic conversion unit 3 is configured to be small and light, and is connected to a receiving unit 22 described later by a multi-channel cable. The electroacoustic conversion unit 3 is selected according to the diagnostic region from among sector scanning, linear scanning, convex scanning, and the like. The electroacoustic conversion unit 3 may include an acoustic matching layer in order to efficiently transmit the photoacoustic wave U. In general, the acoustic impedance of the piezoelectric element material and the living body are greatly different. Therefore, when the piezoelectric element material and the living body are in direct contact with each other, reflection at the interface becomes large and the photoacoustic wave cannot be efficiently transmitted. For this reason, a photoacoustic wave can be efficiently transmitted by inserting the acoustic matching layer comprised with the substance which has an intermediate acoustic impedance between piezoelectric element material and a biological body. Examples of the material constituting the acoustic matching layer include epoxy resin and quartz glass.

  The image generation unit 2 of the photoacoustic imaging apparatus 10 selectively drives the plurality of conversion elements 54 constituting the electroacoustic conversion unit 3 and gives a predetermined delay time to the electric signal from the electroacoustic conversion unit 3 to adjust the electric signal. A receiving unit 22 that generates a received signal by performing phase addition, a scanning control unit 24 that controls the selection drive of the conversion element 54 and the delay time of the receiving unit 22, and various types of received signals obtained from the receiving unit 22 And a signal processing unit 25 for performing the above processing.

  As shown in FIG. 2, the reception unit 22 includes an electronic switch 53, a preamplifier 55, a reception delay circuit 56, and an adder 57.

  When receiving the photoacoustic wave in the photoacoustic scanning, the electronic switch 53 selects a predetermined number of adjacent conversion elements 54. For example, when the electroacoustic conversion unit 3 is composed of 192 conversion elements CH1 to CH192 of the array type, such an array conversion element is converted into an area 0 (area of conversion elements from CH1 to CH64) by the electronic switch 53. ), Area 1 (region of the conversion element from CH65 to CH128) and area 2 (region of the conversion element from CH129 to CH192) are handled by being divided. When an array type conversion element composed of N conversion elements in this way is handled as a group (area) of n (n <N) adjacent transducers, and an imaging operation is performed for each area, It is not necessary to connect preamplifiers or A / D conversion boards to the conversion elements of all channels, the structure of the probe unit 70 can be simplified, and an increase in cost can be prevented. In addition, when a plurality of optical fibers are arranged so that each area can be individually irradiated with light, the light output per time does not need to be increased, so an expensive light source with a large output is used. There is also an advantage that it is not necessary. Each electric signal obtained by the conversion element 54 is supplied to the preamplifier 55.

  The preamplifier 55 amplifies a minute electric signal received by the conversion element 54 selected as described above, and ensures a sufficient S / N.

  The reception delay circuit 56 forms a converged reception beam by matching the phase of the photoacoustic wave U from a predetermined direction with the electrical signal of the photoacoustic wave U obtained from the conversion element 54 selected by the electronic switch 53. Give a delay time to do.

  The adder 57 adds together the electrical signals of a plurality of channels delayed by the reception delay circuit 56 to combine them into one reception signal. By this addition, phasing addition of acoustic signals from a predetermined depth is performed, and a reception convergence point is set.

  The scanning control unit 24 includes a beam focusing control circuit 67 and a conversion element selection control circuit 68. The conversion element selection control circuit 68 supplies position information of a predetermined number of conversion elements 54 at the time of reception selected by the electronic switch 53 to the electronic switch 53. On the other hand, the beam focusing control circuit 67 supplies delay time information for forming reception convergence points formed by a predetermined number of conversion elements 54 to the reception delay circuit 56.

  The signal processing unit 25 includes a filter 66, a signal processor 59, an A / D converter 60, and an image data memory 62. The electrical signal output from the adder 57 of the receiving unit 22 removes unnecessary noise in the filter 66 of the signal processing unit 25, and thereafter, the signal processor 59 performs logarithmic conversion of the amplitude of the received signal to make the weak signal relative. Stress. In general, the received signal from the subject 7 has an amplitude with a wide dynamic range of 80 dB or more, and a weak signal is emphasized in order to display it on a normal monitor having a dynamic range of about 23 dB. Amplitude compression is required. The filter 66 has a band pass characteristic, and has a mode for extracting a fundamental wave in a received signal and a mode for extracting a harmonic component. The signal processor 59 performs envelope detection on the logarithmically converted received signal. The A / D converter 60 A / D converts the output signal of the signal processor 59 to form photoacoustic image data for one line. The photoacoustic image data for one line is stored in the image data memory 62.

  The image data memory 62 is a storage circuit that stores the photoacoustic image data generated as described above. Under the control of the system control unit 4, cross-sectional data is read from the image data memory 62, and photoacoustic image data of the cross-section is generated by spatially interpolating at the time of reading.

  The display unit 6 includes a display image memory 63, a photoacoustic image data converter 64, and a monitor 65. The display image memory 63 is a buffer memory that temporarily stores photoacoustic image data to be displayed on the monitor 65, and the photoacoustic image data for one line from the image data memory 62 is stored in the display image memory 63. It is synthesized into one frame. The photoacoustic image data converter 64 performs D / A conversion and television format conversion on the composite image data read from the display image memory 63, and the output is displayed on the monitor 65.

  The operation unit 5 includes a keyboard, a trackball, a mouse, and the like on the operation panel, and is used by an apparatus operator to input necessary information such as patient information, imaging conditions of the apparatus, and a display section.

  The system control unit 4 includes a CPU (not shown) and a storage circuit (not shown), and controls each unit such as the optical transmission unit 1, the image generation unit 2, and the display unit 6 and controls the entire system according to a command signal from the operation unit 5. Supervised. In particular, the input command signal of the operator sent via the operation unit 5 is stored in the internal CPU.

  Next, the operation of the present invention will be described.

  As shown in FIG. 3, the photoacoustic imaging device 10 and the probe unit 70 of the present invention are configured so that one and the other of two laser beams Lx and Ly incident on different positions from the upstream side of the optical system are predetermined. The optical branching section 12 having one branch DOE 40 that branches as the first plurality of branch lights Lxd and the second plurality of branch lights Lyd according to the branch pattern, and the first plurality of optical fibers 13x having a core / cladding structure. The first bundle fiber 14x includes a first bundle fiber 14x, and one end face 13e of the first plurality of optical fibers 13x on one end face 14e of the first bundle fiber 14x is arranged corresponding to the branch pattern. A second bundle fiber including a bundle fiber 14x and a second plurality of optical fibers 13y having a core / cladding structure. A second bundle fiber 14y in which one end face 13e of the second plurality of optical fibers 13y on the one end face 14e of the second bundle fiber 14y is arranged corresponding to the branch pattern, The first bundle fiber 14x causes each of the first plurality of branched lights Lxd to enter each of the cores of the first plurality of optical fibers 13x from the one end face 14e of the first bundle fiber 14x, and The first plurality of branched Lxd lights incident on the core of the plurality of optical fibers 13x are arranged so as to be guided to the light irradiation unit 15 connected to the other end face 14e of the first bundle fiber 14x. The second bundle fiber 14y is a core of the second plurality of optical fibers 13y for each of the second plurality of branched lights Lyd. Each of the second plurality of branched lights Lyd incident on the core of the second plurality of optical fibers 13y is incident on the other end of the second bundle fiber 14y. It is arrange | positioned so that it may guide to the light irradiation part 15 connected in the end surface 14e of this. That is, according to the present invention, the branch pattern of the branch DOE 40 and the arrangement pattern of the end faces 13e of the plurality of optical fibers on the incident end face 14e of the bundle fiber are associated with each other. Alignment can be performed at once. This eliminates the need to separately align each of the plurality of branched lights and each of the plurality of optical fibers, and facilitates the alignment of each of the plurality of branched lights and each of the plurality of optical fibers.

  As a result, high-energy pulsed laser light can be transmitted, and a high-quality photoacoustic image can be captured. Furthermore, the flexibility and durability of the cord portion of the probe unit can be easily achieved.

  Furthermore, as in the present invention, two laser beams are branched and guided by two bundle fibers, respectively, thereby making it easier to align each of the plurality of branched lights and each of the plurality of optical fibers. It becomes possible to. This is because, for example, it is easier to align a bundle fiber including 50 optical fibers than to align a bundle fiber including 100 optical fibers. Note that the number of laser beams incident on the branch DOE is not limited to two. That is, three or more laser beams may be branched by the branch DOE, and a plurality of branched beams may be guided by three or more bundle fibers arranged corresponding to each laser beam. In order to manufacture the photoacoustic imaging apparatus, in view of the alignment accuracy of the plurality of optical fibers in the bundle fiber, it may be set so as to reduce the labor required for alignment.

"Design change of operation method of photoacoustic imaging device, probe unit and photoacoustic imaging device"
The photoacoustic imaging device 10 and the probe unit 70 of the present invention are not limited to the embodiment described above. In the following, only one optical system (that is, the condensing lens system 44x and the bundle fiber 14x) will be described unless particularly required. However, the following design items are naturally applicable to the other optical system (that is, the condensing lens system 44y and the bundle fiber 14y).

  For example, the photoacoustic imaging apparatus 10 and the probe unit 70 of the present invention include a position adjusting unit 14a that adjusts the positional relationship between the one end surface 14e of the bundle fiber 14x and the light branching unit 12, as shown in FIG. Can be configured. Alternatively, a position adjusting unit that controls the branch DOE 40 may be provided. The position adjusting unit 14a can be configured to measure the measurement light L emitted from the probe unit 70 and automatically adjust the positional relationship so that the measured light quantity becomes the maximum value. This makes it easier to align each of the plurality of branched lights Lxd and each of the plurality of optical fibers 13x.

  Further, for example, the photoacoustic imaging device 10 and the probe unit 70 of the present invention are configured such that the optical branching unit 12 has a homogenizer optical element 41 on the upstream side of the optical system of the branching DOE 40 as shown in FIG. Can do. The homogenizer optical element 41 arranged in this way makes the intensity profiles of the beams of the plurality of branched lights Lxd uniform. Therefore, it is possible to prevent the branched light Lxd having a high energy density from locally entering the optical fiber 13x and damaging the optical fiber 13x. That is, the plurality of branched lights Lxd can be guided so as not to exceed the damage threshold energy of the optical fiber 13x throughout the plurality of branched lights Lxd.

  Further, for example, the photoacoustic imaging device 10 and the probe unit 70 of the present invention are configured such that the optical branching unit 12 has a holographic diffusion plate 42 on the downstream side of the optical system of the branching DOE 40, as shown in FIG. be able to. FIG. 9 shows a configuration in which the holographic diffusion plate 42 is provided between the condenser lens system 44x and the incident end face 14e of the bundle fiber 14x. A configuration may be provided between the optical lens system 44x and the optical lens system 44x. However, the holographic diffusion plate 42 is provided between the condensing lens system 44x and the incident end face 14e of the bundle fiber 14x from the viewpoint of easy adjustment when changing the distance to control the condensing spot diameter. Is preferred. The holographic diffuser plate 42 arranged in this manner changes the direction in which the condensed spot diameter of the plurality of branched lights Lxd increases, and the plurality of branched lights when entering the core 13a on the incident end face 14e of the bundle fiber 14x. The beam diameter of Lxd is optimized. Therefore, a plurality of branched lights Lxd can be guided so as not to exceed the damage threshold energy density of the optical fiber 13x.

  Further, for example, the photoacoustic imaging device 10 and the probe unit 70 of the present invention are configured such that the optical branching unit 12 has a variable beam expander 43 on the upstream side of the optical system of the branching DOE 40, as shown in FIG. be able to. Since the variable beam expander 43 arranged in this way can change the beam diameter as appropriate for each wavelength of the laser light Lx used in photoacoustic imaging, the converging diameter of the plurality of branched lights Lxd (bundle fiber 14x The diameter of the incident end face 14e when entering the core 13a can be controlled. It is also possible to measure the measurement light L emitted from the probe unit 70 and automatically control the beam diameter for each wavelength of the laser light Lx so that the measured light quantity becomes the maximum value.

  Further, for example, as shown in FIG. 11, the photoacoustic imaging apparatus 10 and the probe unit 70 of the present invention divide one laser beam Lo into two by a beam splitter 11a, a mirror 11b, etc. You may comprise so that it may be set to Ly.

  Further, for example, the photoacoustic imaging device 10 and the probe unit 70 of the present invention are configured such that two laser beams emitted from both ends of the semiconductor laser 11c are laser beams Lx and Ly, as shown in FIG. May be. With this configuration, a plurality of branched lights can be efficiently generated without using a complicated optical system.

  Further, for example, in the photoacoustic imaging apparatus 10 and the probe unit 70 of the present invention, as shown in FIG. 13, the light irradiation unit 15 is the other end face 13e of the plurality of optical fibers 13x and 13y, and the other end face 13e. Can be configured to be arranged in a line at intervals. With this configuration, it is not necessary to provide an optical system with a complicated structure at the probe unit tip 71, and a uniform line-shaped light source can be obtained. Further, a more uniform line light source can be obtained by adjusting the distance in consideration of the intensity of the branched lights Lxd and Lyd emitted from each of the plurality of optical fibers 13x and 13y. For example, it is preferable to adjust the distance by widening when the intensity of the branched light is strong, and narrowing the light when the intensity is weak.

  Further, for example, as shown in FIG. 14, the photoacoustic imaging device 10 and the probe unit 70 of the present invention are a light guide plate 72 having a light emitting portion 15 having a tapered shape, and the other one of the bundle fibers 14x and 14y. The end surface 14e can be configured to be connected to the end surface on the short side of the light guide plate 72 in a detachable state. For example, in FIG. 14, the other end face 14 e of the bundle fibers 14 x and 14 y and the end face on the short side of the light guide plate 72 are connected to each other in the connector portion 73. With this configuration, when the bundle fibers 14x and 14y are damaged, it is possible to replace only the bundle fiber, and the maintenance performance is improved.

DESCRIPTION OF SYMBOLS 1 Light transmission part 2 Image generation part 3 Electroacoustic conversion part 4 System control part 5 Operation part 6 Display part 7 Subject 10 Photoacoustic imaging device 11 Light source part 12 Optical branch part 13x, 13y Optical fiber 13a Optical fiber core 13b Light Fiber Clad 14x, 14y Bundle Fiber 14a Bundle Fiber Position Adjuster 15 Light Irradiator 22 Receiver 24 Scan Controller 25 Signal Processor 40 Branch Diffraction Optical Element (Branch DOE)
40a Branch DOE position adjustment unit 41 Homogenizer optical element 42 Holographic diffuser plate 43 Variable beam expander 44x, 44y Condensing lens system 44a Lens position adjustment unit 70 Probe unit 71 Probe unit tip 72 Light guide plate 73 Connector part L Measurement light Lxd, Lyd Branched light M Reflective mask U Photoacoustic wave

Claims (13)

A light irradiating unit that irradiates measurement light into the subject, an electroacoustic conversion unit that detects a photoacoustic wave generated in the subject by the irradiation of the measuring light, and converts the photoacoustic wave into an electrical signal; In a photoacoustic imaging device comprising an image generation unit that generates a photoacoustic image based on the electrical signal,
One branch diffraction in which one and the other of two laser beams incident on different positions from the upstream side of the optical system are branched as a first plurality of branched lights and a second plurality of branched lights, respectively, according to a predetermined branch pattern An optical branch having an optical element;
A first bundle fiber including a first plurality of optical fibers having a core / clad structure, wherein one end face of the first plurality of optical fibers on one end face of the first bundle fiber is the first bundle fiber. The first bundle fiber arranged corresponding to the branch pattern;
A second bundle fiber including a second plurality of optical fibers having a core / cladding structure, wherein one end face of the second plurality of optical fibers on one end face of the second bundle fiber is The second bundle fiber arranged corresponding to the branch pattern,
The first bundle fiber causes each of the first plurality of branched lights to enter each of the cores of the first plurality of optical fibers from the one end face of the first bundle fiber, and The first plurality of branched lights incident on the core of one of the plurality of optical fibers are arranged so as to be guided to the light irradiation unit connected at the other end face of the first bundle fiber. Yes,
The second bundle fiber causes each of the second plurality of branched lights to enter each of the cores of the second plurality of optical fibers from the one end surface of the second bundle fiber, and The second plurality of branched lights incident on the core of the plurality of two optical fibers are arranged so as to be guided to the light irradiation unit connected at the other end face of the second bundle fiber. Yes,
The photoacoustic imaging apparatus, wherein the light irradiation unit irradiates the first plurality of branched lights and the second plurality of branched lights as the measurement light.   A position adjusting unit that adjusts a positional relationship between the one end surface of the first bundle fiber and the optical branching unit and a positional relationship between the one end surface of the second bundle fiber and the optical branching unit; The photoacoustic imaging apparatus according to claim 1. The light branching section has a first condenser lens system and a second condenser lens system on the downstream side of the optical system of the branch diffractive optical element;
The first condenser lens system is arranged so that a focal point of the first condenser lens system corresponds to an incident position of the one laser beam in the branch diffractive optical element;
The second condenser lens system is arranged such that the focal point of the second condenser lens system corresponds to the incident position of the other laser beam in the branch diffractive optical element. The photoacoustic imaging device according to claim 1 or 2.   The optical branching unit includes a lens position adjusting unit that adjusts a position of the first condenser lens system in the optical axis direction and a position of the second condenser lens system in the optical axis direction. Item 4. The photoacoustic imaging apparatus according to Item 3.   5. The optical branching unit according to claim 1, further comprising a homogenizer optical element corresponding to each of the optical paths of the two laser beams on the upstream side of the optical system of the branching diffractive optical element. The photoacoustic imaging device described in 1.   6. The holographic diffusion plate according to claim 1, wherein the optical branching unit has a holographic diffusion plate corresponding to each of the optical paths of the two laser beams on the downstream side of the optical system of the branched diffractive optical element. A photoacoustic imaging apparatus according to claim 1.   7. The optical branching unit according to claim 1, further comprising a variable beam expander corresponding to each of the optical paths of the two laser beams on the upstream side of the optical system of the branching diffractive optical element. A photoacoustic imaging apparatus according to claim 1. The branch pattern has a hexagonal structure;
8. The photoacoustic according to claim 1, wherein the one end faces of each of the first plurality of optical fibers and the second plurality of optical fibers are arranged in a close-packed structure. Imaging device. The one end face of the first bundle fiber has a first reflective mask on the end face such that the core of the first plurality of optical fibers on the end face is exposed;
The one end face of the second bundle fiber has a second reflection mask on the end face so that the core of the second plurality of optical fibers on the end face is exposed. The photoacoustic imaging device according to any one of 1 to 8. The light irradiation section is the other end face of the first plurality of optical fibers and the other end face of the second plurality of optical fibers;
10. The photoacoustic imaging apparatus according to claim 1, wherein the other end face is arranged in a line at intervals. The light irradiation part is a light guide plate having a tapered shape,
The other end face of the first bundle fiber and the other end face of the second bundle fiber are detachably connected to an end face on the short side of the light guide plate, The photoacoustic imaging device according to claim 1. Irradiating measurement light into a subject, detecting a photoacoustic wave generated in the subject by the irradiation of the measurement light, converting the photoacoustic wave into an electric signal, and photoacoustic image based on the electric signal In the probe unit used in the photoacoustic imaging device that generates
A light irradiator for irradiating measurement light into the subject;
An electroacoustic conversion unit that detects a photoacoustic wave generated in the subject by irradiation of the measurement light and converts the photoacoustic wave into an electric signal;
One branch diffraction in which one and the other of two laser beams incident on different positions from the upstream side of the optical system are branched as a first plurality of branched lights and a second plurality of branched lights, respectively, according to a predetermined branch pattern An optical branch having an optical element;
A first bundle fiber including a first plurality of optical fibers having a core / clad structure, wherein one end face of the first plurality of optical fibers on one end face of the first bundle fiber is the first bundle fiber. The first bundle fiber arranged corresponding to the branch pattern;
A second bundle fiber including a second plurality of optical fibers having a core / cladding structure, wherein one end face of the second plurality of optical fibers on one end face of the second bundle fiber is The second bundle fiber arranged corresponding to the branch pattern,
The first bundle fiber causes each of the first plurality of branched lights to enter each of the cores of the first plurality of optical fibers from the one end face of the first bundle fiber, and The first plurality of branched lights incident on the core of one of the plurality of optical fibers are arranged so as to be guided to the light irradiation unit connected at the other end face of the first bundle fiber. Yes,
The second bundle fiber causes each of the second plurality of branched lights to enter each of the cores of the second plurality of optical fibers from the one end surface of the second bundle fiber, and The second plurality of branched lights incident on the core of the plurality of two optical fibers are arranged so as to be guided to the light irradiation unit connected at the other end face of the second bundle fiber. Yes,
The probe unit, wherein the light irradiation unit irradiates the first plurality of branched lights and the second plurality of branched lights as the measurement light. Irradiating measurement light into a subject, detecting a photoacoustic wave generated in the subject by the irradiation of the measurement light, converting the photoacoustic wave into an electric signal, and photoacoustic image based on the electric signal In a method of operating a photoacoustic imaging device that generates
One and the other of two laser beams incident on different positions on the branch diffractive optical element from the upstream side of the optical system are respectively divided into a plurality of first branches according to a predetermined branch pattern defined by the branch diffractive optical element. Branching as light and a second plurality of branched lights,
A first bundle fiber including a first plurality of optical fibers having a core / clad structure, wherein one end face of the first plurality of optical fibers on one end face of the first bundle fiber is the first bundle fiber. The first bundle fiber arranged corresponding to the branch pattern;
A second bundle fiber including a second plurality of optical fibers having a core / cladding structure, wherein one end face of the second plurality of optical fibers on one end face of the second bundle fiber is Using the second bundle fiber arranged corresponding to the branch pattern,
Causing each of the first plurality of branched lights to enter each of the cores of the first plurality of optical fibers from the one end face of the first bundle fiber;
Guiding the first plurality of branched lights incident on the cores of the first plurality of optical fibers to the light irradiation unit;
Allowing each of the second plurality of branched lights to enter each of the cores of the second plurality of optical fibers from the one end face of the second bundle fiber;
Guiding the second plurality of branched lights incident on the core of the second plurality of optical fibers to the light irradiation unit;
An operation method of a photoacoustic imaging apparatus, wherein the first plurality of branched lights and the second plurality of branched lights guided to the light irradiation unit are irradiated as the measurement light.