JP2002209893A - Ultrasonic diagnostic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic diagnostic device, in which the number of optical fibers for transmitting the input/output light beams of a plurality of ultrasonic wave detecting elements arranged in a two-dimensional state can be reduced and the sound pressure of ultrasonic wave which is received by the ultrasonic wave detecting elements can be correctly measured without requiring complicated adjustment in a light source and the ultrasonic wave detecting elements. SOLUTION: This device is provided with an optical waveguide for supplying an incident light from a first end part to plurality of second end parts by branching, multiplexing the light beams coming from the second end parts and supplying them to the first end part, a plurality of fiber black gratings which are respectively formed in the second end parts of the optical waveguide and mutually different in light reflection wave length characteristics, the light source for generating the light having a prescribed wave length band, a plurality of light position detectors for respectively detecting the incident positions of emission light beams from a demultiplexer, and a signal processing part, or the like, for obtaining sound pressure information of ultrasonic wave which is received by the fiber black gratings based on the output signals of the light position detectors.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic probe using an ultrasonic probe having a two-dimensional sensor array using a plurality of ultrasonic detecting elements for modulating incident light based on an applied ultrasonic wave. The present invention relates to an ultrasonic diagnostic apparatus for performing medical diagnosis by transmitting and receiving.

[0002]

2. Description of the Related Art Conventionally, when obtaining a three-dimensional image using ultrasonic waves, a plurality of two-dimensional images of a cross section in the depth direction have been obtained and synthesized. This two-dimensional image is obtained by scanning a one-dimensional sensor array with a position sensor, and a three-dimensional image is obtained by synthesizing a plurality of two-dimensional images acquired in time series.

However, according to this method, since there is a time lag in the scanning direction of the one-dimensional sensor array,
Since the cross-sectional images at different times will be synthesized,
The composite image is blurred. Therefore, it is not suitable for imaging a moving subject such as a living body.

In order to acquire a three-dimensional image in real time, a two-dimensional sensor array capable of acquiring a two-dimensional image without scanning the sensor array is essential, and development of such a sensor array is desired. ing.

In an ultrasonic diagnostic apparatus, PZT (lead zirconate titanate) is used as an element for transmitting and receiving ultrasonic waves.
It is common to use a piezoelectric element made of a ceramic piezoelectric material such as PVDF or a polymer piezoelectric material such as PVDF (polyvinylidene fluoride). A method of manufacturing a two-dimensional sensor array using this element has been studied. I have. However, according to this method, processing for miniaturization of the element is difficult, which leads to an increase in cost due to a decrease in yield and an increase in the number of wirings connected to a large number of microelements. Further, even if these problems are solved, there still remains a problem that the sensitivity is reduced due to an increase in electrical impedance due to fine wiring.

Also, a method of manufacturing a two-dimensional sensor array using a plurality of ultrasonic detecting elements including a minute capacitor and changing the capacitance of the capacitor based on the applied ultrasonic wave (capacitance method) ) And a method of manufacturing a two-dimensional sensor array by combining a composite of a plurality of piezoelectric elements made of PZT and a resin material with an integrated circuit (PZT composite method). However, according to these methods, the above-described cost increase and increase in electrical impedance can be suppressed, but the increase in the number of wirings connected to a large number of fine elements cannot be solved.

Also, an optical fiber array including a plurality of optical fibers into which light generated in a light source is incident on a first end, and a second optical fiber opposite to the first end of each optical fiber.
Of two-dimensional sensor arrays using a plurality of ultrasonic detection elements that modulate light incident through an optical fiber based on applied ultrasonic waves formed at the end of the optical fiber is studied. Have been. According to this method, since the piezoelectric element is not used for the ultrasonic detection element, the above-described cost increase and increase in electrical impedance do not occur. However, since the detection signals of a plurality of ultrasonic detection elements are passed through separate optical fibers, if the number of ultrasonic detection elements is increased for the purpose of improving image quality or the like, the number of optical fibers also increases.

Further, according to the optical system, the detection of ultrasonic waves is performed by detecting the amount of light of a predetermined wavelength component contained in the light emitted from the ultrasonic detection element using a photodetector.
However, the characteristics of the ultrasonic detection element show a steep change depending on its structure, and also change due to environmental changes such as temperature changes. For this reason, the variation between the wavelength of the light source and the reflection wavelength characteristic of the ultrasonic detecting element is a serious problem in practical use. Therefore, accurate adjustment is required for the light source and the ultrasonic detection element.

[0009]

In view of the above, the present invention has been made to reduce the number of optical fibers for transmitting input / output light of a plurality of ultrasonic detecting elements arranged two-dimensionally. To provide an ultrasonic diagnostic apparatus capable of accurately measuring the sound pressure of an ultrasonic wave received by an ultrasonic detection element without requiring complicated adjustments in a light source and a plurality of ultrasonic detection elements. With the goal.

[0010]

SUMMARY OF THE INVENTION In order to solve the above problems, an ultrasonic diagnostic apparatus according to the present invention splits light supplied from a first end to a plurality of second ends and supplies the light. And combine the light returning from the plurality of second ends to form the first light.
And a plurality of ultrasonic detecting elements formed at a plurality of second ends of the optical waveguide and modulating and reflecting the incident light based on the sound pressure of the applied ultrasonic wave, respectively. An ultrasonic probe including a plurality of ultrasonic detecting elements having different reflection wavelength characteristics of light, and an optical transmitting and receiving means for transmitting and receiving light between the ultrasonic probe, A light source that generates light having a spectrum including a wavelength component, a demultiplexing unit that splits light including a plurality of wavelength components for each predetermined wavelength component, and an optical waveguide that outputs the light generated in the light source through an optical fiber. And a plurality of light position detecting means for detecting an incident position of a plurality of lights emitted from the demultiplexing means, and a switching means for supplying light supplied to the optical fiber and outputting the light supplied through the optical fiber to the demultiplexing means. Transmission / reception means and output signals of each of the plurality of light position detection means Based on comprises the corresponding signal processing means for the ultrasonic detecting element to obtain an ultrasonic sound pressure information received is.

According to the present invention, when light containing a plurality of wavelength components is supplied to an ultrasonic probe via an optical fiber, the light is demultiplexed in an optical waveguide connected to the optical fiber,
Light is incident on a plurality of ultrasonic detection elements having different reflection wavelength characteristics from each other. These ultrasonic detecting elements change the reflection wavelength based on the sound pressure of the applied ultrasonic waves and environmental changes (for example, temperature changes). Light reflected by these ultrasonic detection elements is multiplexed in an optical waveguide and supplied to an optical fiber. Therefore, since a plurality of modulated lights are multiplexed, the number of optical fibers connected to the ultrasonic probe can be reduced.

Further, according to the present invention, even if the reflection wavelength characteristics of a plurality of ultrasonic detection elements change, a light source that generates light having a spectrum that always includes these reflection wavelengths is selected. In addition, complicated adjustment in a plurality of ultrasonic detection elements can be eliminated. Then, each incident position of a plurality of lights having different wavelengths emitted from the demultiplexing unit is detected by using the corresponding optical position detector, and based on the output signal of each optical position detector, the signal processing unit is detected. Acquires the sound pressure information of the ultrasonic waves received by each ultrasonic detection element. Therefore, even when there is an environmental change such as a temperature change, the sound pressure of the ultrasonic wave received by the ultrasonic detecting element can be accurately measured.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. Note that the same components are denoted by the same reference numerals, and description thereof will be omitted. FIG. 1 is a block diagram showing a configuration of an ultrasonic diagnostic apparatus according to one embodiment of the present invention. As shown in FIG. 1, the ultrasonic diagnostic apparatus includes an ultrasonic probe 10 used in contact with a subject. The ultrasonic probe 10 has a plurality of ultrasonic generating elements 30 (1) to 30 (N) having an ultrasonic generating function.
(N is an integer of 2 or more) arranged in one line and a plurality of one-dimensional transmission array units 11 and a plurality of ultrasonic detection elements 40 (1) to 40 (N) having an ultrasonic detection function in one line. And a plurality of one-dimensional receiving array units 12 arranged in a row. In the ultrasonic probe 10, a two-dimensional sensor array is realized by alternately arranging a plurality of one-dimensional transmission array units 11 and a plurality of one-dimensional reception array units 12.

The ultrasonic diagnostic apparatus includes a plurality of drive signal generating circuits 14 for generating drive signals under the control of the timing control unit 13. The plurality of one-dimensional transmission array units 11 included in the ultrasound probe 10 are transmitted from the plurality of ultrasound generation elements 30 (1) to 30 (N) based on the drive signal generated by the corresponding drive signal generation circuit 14. An ultrasonic wave is generated, and the ultrasonic wave is transmitted to the subject. Then, the plurality of ultrasonic waves reflected from the subject are received by the plurality of one-dimensional receiving array units 12 included in the ultrasonic probe 10.

The ultrasonic diagnostic apparatus further includes a plurality of optical transmitting / receiving units 15 for transmitting / receiving optical signals to / from the corresponding one-dimensional receiving array unit 12. This optical signal contains a plurality of wavelength components. The optical signal supplied from the optical transmission / reception unit 15 to the one-dimensional reception array unit 12 is split into a plurality of lights, and the plurality of ultrasonic detection elements 40 (1) to 40 (N) included in the one-dimensional reception array unit 12 ). These ultrasonic detecting elements 40 (1) to 40 (1) to 40
(N) has different light reflection wavelength characteristics. When receiving the ultrasonic waves, the plurality of ultrasonic detection elements 40 (1) to 40 (N) change their reflection wavelength characteristics and modulate the incident light. A plurality of ultrasonic detection elements 40 (1) to 40
The lights of different wavelength components reflected from (N) are multiplexed into one light and supplied to the optical transmitting / receiving unit 15.

The plurality of optical transmitting / receiving sections 15 are provided with a plurality of ultrasonic detecting elements 40 included in the corresponding one-dimensional receiving array section 12.
(1) Includes a plurality of optical position detectors that respectively detect reflected light from (N) to 40 (N) and output detection signals (position signals). The optical position detector will be described later in detail. The position signals output from the plurality of optical position detectors are input to a signal processing unit 17 included in the signal processing unit 16. The signal processing unit 17 includes a timing control unit 13
Under the control described above, the position signals output from the plurality of optical position detectors are fetched after a lapse of a predetermined time since the plurality of drive signal generation circuits 14 generate the drive signals. Signal processing unit 17
Are based on the position signals output from the plurality of optical position detectors, and the corresponding ultrasonic detection elements 40 (1) to 40 (N)
To obtain the sound pressure information of the ultrasonic wave received by the user.

The output signal of the signal processing unit 17 is supplied to the A /
The digital signal is converted in the D converter 18. A /
A primary storage unit 19 is connected to the D converter 18 and stores the acquired plurality of plane data. The image processing unit 20 reconstructs two-dimensional data or three-dimensional data based on the data. The reconstructed data is interpolated,
The image is subjected to processing such as response modulation processing and gradation processing and is displayed on the image display unit 21. Further, the data processed by the image processing unit 20 is stored in the secondary storage unit 22.

FIG. 2A is a perspective view showing a configuration of an ultrasonic probe included in the ultrasonic diagnostic apparatus shown in FIG. 1, and FIG. 2B is used for this ultrasonic probe. FIG. 2 is a diagram showing an example of the arrangement of an ultrasonic wave generating element and an ultrasonic wave detecting element to be used.
(C) is a figure which shows another example of arrangement. As shown in FIG. 2A, in this ultrasonic probe, a plurality of one-dimensional transmission array units 11 and a plurality of one-dimensional reception array units 12 are arranged so as to be alternately arranged. Note that a probe for transmitting ultrasonic waves may be configured by a plurality of one-dimensional transmission array units, and a probe for receiving ultrasonic waves may be configured by a plurality of one-dimensional reception array units. The plurality of one-dimensional transmission array units 11 include a plurality of ultrasonic generating elements 30 arranged in a line.
(1) to 30 (N). The plurality of ultrasonic generating elements 30 (1) to 30 (N) include a piezoelectric element made of PZT or the like, and a corresponding drive signal generating circuit (see FIG. 1).
An ultrasonic wave is generated based on the drive signal input from the computer. On the other hand, the plurality of one-dimensional reception array units 12 include a plurality of ultrasonic detection elements 40 (1) to 40 (N) arranged in a line.

In the present embodiment, as shown in FIG. 2A, a plurality of one-dimensional transmission array units 11 and a plurality of one-dimensional reception array units 12 are arranged at a right angle to the ultrasonic wave transmission direction. Are alternately arranged in one direction. Therefore, when this ultrasonic probe is viewed from the transmitting and receiving side of the ultrasonic wave,
As shown in FIG. 2B, a plurality of ultrasonic generating elements (white squares) and a plurality of ultrasonic detecting elements (black squares)
Each forms a two-dimensional array. It should be noted that the number of ultrasonic wave generating elements was made smaller than the number of ultrasonic wave detecting elements, and FIG.
As shown in (1), a plurality of ultrasonic wave generating elements may be arranged on a cloth.

FIG. 3A is a perspective view showing a configuration of a one-dimensional receiving array section included in the ultrasonic probe shown in FIG. 2, and FIG. 3B is a perspective view of the one-dimensional receiving array section. It is a projection view. As shown in FIGS. 3A and 3B, the one-dimensional receiving array unit includes a plurality of inverted L-shaped optical waveguides 50 (1) to 50 (N) having different waveguide lengths. Each of these optical waveguides 50 (1) to 50 (N) has a cross section of 1
They are formed on the silicon substrate 53 so as to be arranged in a line.
At the tips of the plurality of optical waveguides 50 (1) to 50 (N),
A fiber black grating (FB) that functions as an ultrasonic detecting element by reflecting light having a predetermined wavelength
G) 51 (1) to 51 (N) are formed.

Here, a plurality of FBGs 51 (1) -51
(N) will be described in detail. The FBG is formed by alternately stacking two types of material layers (light propagation media) having different refractive indexes so that the refractive index periodically changes at a pitch satisfying the black reflection condition. When the pitch of the periodic structure of each layer is d, the wavelength of incident light is λ, and the incident angle is θ,
The black reflection condition is represented by the following equation (1). 2d sin θ = Nλ (1) In particular, when the incident angle is 90 °, the expression (1) is further rewritten into the following expression (2). 2d = Nλ (2) The FBG selectively reflects light having a wavelength (black wavelength) satisfying the condition of the expression (2) by the action of black reflection.
Transmits light of a wavelength other than the black wavelength.

In the present embodiment, the FBG 51 (1)
Is determined such that the black wavelength becomes λ ₁ based on the equation (2).
The pitch d of the periodic structure of each layer constituting the FBG 51 (2) is determined based on the formula (2) so that the black wavelength is λ.
₂ (≠ λ ₁ ). Remaining FBG51
The same applies to (3) to 51 (N). Therefore, F
The reflection wavelength characteristics of the BGs 51 (1) to 51 (N) are different from each other. The plurality of FBGs 51 (1) to 51 (N)
It expands and contracts in response to ultrasonic waves and environmental changes (for example, temperature changes). Thereby, each of the FBGs 51 (1) to 51 (1) to 51
The pitch d of the periodic structure of each layer constituting (N) changes,
Change each black wavelength. In this manner, the light incident on each of the FBGs 51 (1) to 51 (N) is modulated based on the ultrasonic waves and environmental changes.

The end of the optical waveguide 50 (1) is connected via an optical fiber 64 to a corresponding optical transceiver (see FIG. 1). On the other hand, the end of the optical waveguide 50 (2)
It is connected to the end of the optical waveguide 50 (1) via a slit 52 (1) serving as a beam splitter. The end of the optical waveguide 50 (3) is connected to the optical waveguide 50 (2) via a slit 52 (2) serving as a beam splitter.
It is connected to the end of (2). Remaining optical waveguide 50
The same applies to (4) to 50 (N). In the present embodiment, by connecting the plurality of optical waveguides 50 (1) to 50 (N) in this manner, the planar lightwave circuit (P
LC: Planar Lightwave Circuit) has been realized.

Here, the operation of the one-dimensional receiving array unit shown in FIG. 3 will be described. When the light L _BRO including a predetermined wavelength range (λ _{1 to} λ _N ) is supplied to the one-dimensional receiving array unit, as shown in FIG.
Each time the signal passes through (1) to 52 (N-1), it is demultiplexed.
The light L ₁ (wavelength: λ ₁ ) incident on the optical waveguide 50 ( ₁ ) is
The light is reflected by the FBG 51 (1) toward the optical waveguide 50 (1), and is modulated into light L ₁ ′ based on ultrasonic waves and environmental fluctuations received by the FBG 51 (1). The optical waveguide 50
The light L ₂ (wavelength: λ ₂ ) incident on ( ₂ ) is
(2) is reflected toward the optical waveguide 50 (2), and F
The light is modulated into the light L ₂ ′ based on the ultrasonic wave received by the BG 51 (2) and the environmental fluctuation. Remaining light L included in light L _BRO
The same applies to ₃ (wavelength: λ ₃ ) to L _N (wavelength: λ _N ). The outgoing lights L ₁ ′ to L _N ′ of the respective FBGs 51 (1) to 51 (N) are transmitted to the corresponding slits 52 (1) to 52 (52).
The signals are sequentially multiplexed in (N-1) and supplied to the corresponding optical transmitting / receiving unit (see FIG. 1) via the optical fiber 64.

Next, an example of a manufacturing process of the one-dimensional receiving array unit will be described with reference to FIG. First,
As shown in FIG. 4A, the flame deposition method (Flame Hydrolys
is Deposition), Si on the silicon substrate 100
SiO ₂ lower cladding layer 1 composed of O ₂ glass particles
01 and S containing SiO ₂ —GeO ₂ glass fine particles as components
An iO ₂ -GeO ₂ core layer 102 is formed in order. Further, by heating the silicon substrate 100 to melt the SiO ₂ lower cladding layer 101 and the SiO ₂ —GeO ₂ core layer 102, as shown in FIG. And a core layer 104 are formed.

Next, as shown in FIG. 4C, a resist film 105 corresponding to the core pattern of the optical waveguide included in the one-dimensional receiving array portion is formed on the core layer 104. Further, by performing reactive ion etching (Reactive Ion Etching) on the core layer 104 via the resist film 105, a plurality of cores 106 are formed on the cladding layer 103 as shown in FIG. .

Next, as shown in FIG. 4E, the cladding layer 103 and the plurality of cores 10 are formed by a flame deposition method.
On top of this, an SiO ₂ upper cladding layer 107 containing SiO ₂ glass fine particles as a component is formed. Further, by heating the silicon substrate 100 to melt the SiO ₂ upper cladding layer 107, the SiO ₂ upper cladding layer 107 is made transparent to form a cladding layer 108 as shown in FIG.

Next, as shown in FIG. 4G, a resist film 109 corresponding to the cladding pattern of the optical waveguide included in the one-dimensional receiving array portion is formed on the cladding layer 108. Further, by performing reactive ion etching on the cladding layer 108 through the resist film 109, as shown in FIG.
Is formed, and a plurality of optical waveguides 50 (1), 50
(2), ... are completed.

Next, each of the optical waveguides 50 (1), 50 (5)
As shown in FIG. 4I, FBGs 51 (1), 5 (1),
1 (2),... Are formed. For details of the method of forming the FBG, see, for example, “Fiber Grating” by Hiroo Kanamori (IEICE Vol. 82 No. 7pp.
731-739 July 1999). And FIG.
As shown in (j), the end of the plurality of FBGs 51 (1), 51 (2),... On the silicon substrate 100 is etched away to complete the one-dimensional receiving array unit.

FIG. 5A is a view for explaining an example of the configuration of the optical transmitting / receiving section included in the ultrasonic diagnostic apparatus shown in FIG. 1, and FIG. 5B is included in this optical transmitting / receiving section. FIG. 5C is a diagram illustrating spectral characteristics of a broadband light source, and FIG. 5C is a diagram illustrating reflection wavelength characteristics of a plurality of FBGs included in a corresponding one-dimensional receiving array unit. As shown in FIG.
The optical transmitting and receiving unit 15 includes a plurality of wavelength components (λ ₁ , λ ₂ ,.
_N ) including light L _BRO generated broadband
A light source 61 is included.

The light generated by the broadband light source 61 is shown in FIG.
As shown in (b), a spectrum characteristic including a wavelength band from wavelength λ ₁ to wavelength λ _N is shown. On the other hand, a plurality of FBGs 51 included in the one-dimensional reception array unit 12 shown in FIG.
(1) to (N) show the reflection wavelength characteristics centered on the corresponding wavelengths λ ₁ , λ ₂ ,..., Λ _N as shown in FIG. These reflection wavelength characteristics correspond to the corresponding FBG51.
(1) to (N) change based on environmental fluctuations such as sound pressure of ultrasonic waves received and temperature changes. For this reason, in the present embodiment, even if the reflection wavelength characteristics of the plurality of FBGs 51 (1) to 51 (N) change, a light source that generates light having a spectrum that always includes these reflection wavelengths can be selected. good. This eliminates the need for accurate adjustment of the conventional light source and the plurality of ultrasonic detection elements.

Referring again to FIG. 5A, a circulator 63 for switching the traveling direction of light in accordance with the incident direction is connected to the broadband light source 61 via an optical fiber 62. Light L generated in broadband light source 61
_{The BRO} enters the optical fiber 64 in the circulator 63 and is supplied to the one-dimensional receiving array unit 12. Also,
The light L _BRO ′ supplied from the one-dimensional receiving array unit 12 to the optical fiber 64 enters the optical fiber 65 in the circulator 63.

The circulator 63 has an optical fiber 65
A demultiplexer 66 for demultiplexing light containing a plurality of wavelength components into predetermined wavelength components is connected via the. Duplexer 66
_Separates the light L _BRO ′ incident from the optical fiber 65 into a plurality of lights L ₁ ′ to L _N ′. At the subsequent stage of the demultiplexer 66, the optical position detectors 60 (1) to 60 which detect the respective incident positions of the light L ₁ ′ to L _N ′ emitted therefrom and output position signals are provided.
60 (N) are arranged. As such an optical position detector, for example, a light position detector including a plurality of light receiving elements (for example, a photodiode or a phototransistor) arranged in one line is used.
-Dimensional array photodetector and position detection element (PSD: Positi
on Sensitive Detector). The position signals output from the plurality of optical position detectors 60 (1) to 60 (N) are input to a signal processing unit included in the signal processing unit shown in FIG.

Here, the process of measuring the sound pressure of the ultrasonic wave in the ultrasonic diagnostic apparatus of the present embodiment will be described with reference to FIG. One-dimensional receiving array unit 12 shown in FIG.
The reflection wavelength characteristics of a plurality of FBGs 51 (1) to 51 (N) included in the FBGs 51 (1) to 51 (N) change based on environmental changes such as sound pressure of ultrasonic waves and temperature changes received by the corresponding FBGs 51 (1) to 51 (N). I do. As a result, as shown in FIG.
The light L ₁ ′ emitted from the light source changes its incident position on the optical position detector 60 (1). The same applies to the remaining lights L ₂ ′ to L _N ′ emitted from the duplexer 66. In FIG. 6, the broken line indicates the incident optical path when the sound pressure applied to the FBG 51 (1) is zero. Also, the dash-dot line
The incident light path when the sound pressure applied to the FBG 51 (1) is the maximum negative sound pressure, and the two-dot chain line indicates the incident light path when the sound pressure applied to the FBG 51 (1) is the maximum positive sound pressure.

When no ultrasonic wave is applied to the FBG 51 (1), the reflection wavelength characteristic of the FBG 51 (1) changes based only on environmental fluctuations. For this reason, the position signal of the light position detector 60 (1) at this time includes only the influence of the environmental change. On the other hand, the ultrasonic wave is FBG51 (1)
, The reflection wavelength characteristic of the FBG 51 (1) changes based on both the ultrasonic wave and the environmental fluctuation. Therefore, the position signal of the light position detector 60 (1) at this time includes the influence of both the ultrasonic wave and the environmental fluctuation.

Therefore, in the present embodiment, the signal processing unit 17 periodically (for example, an ultrasonic signal) outputs the position signal from the optical position detector 60 (1) when the ultrasonic wave is not applied to the FBG 51 (1). (When the ultrasonic diagnostic apparatus is started), and furthermore, this position signal is used as a reference zero point signal, and the change in the position signal output from the optical position detector 60 (1) is determined by FBG5.
1 (1) is read out as a change in sound pressure applied to it. Remaining F
The same applies to BGs 51 (2) to 51 (N). As a result, even when there is an environmental change such as a temperature change, the FB
The sound pressure of the ultrasonic waves received by each of G51 (1) to G51 (N) can be accurately measured.

FIG. 7 is a diagram showing a configuration example of a duplexer included in the optical transmitting / receiving section shown in FIG. FIG. 7 shows a demultiplexer using an arrayed-wavelength grating (AWG), which is a kind of planar lightwave circuit, as a demultiplexer. This demultiplexing circuit includes an input-side slab waveguide 71 to which one input waveguide 70 is connected, and an output-side slab waveguide 73 to which a plurality of output waveguides 72 (1) to 72 (N) are connected. Are connected by a plurality of arrayed waveguides 74 (1) to 74 (N) having a constant waveguide length difference.

The input side slab waveguide 71 is
The output slab waveguide 73 has a sector shape with the end of the zero as the center of curvature.
It has a fan shape with the end of (N) as the center of curvature. Each of the plurality of array waveguides 74 (1) to 74 (N) has an optical axis whose input side slab waveguide 71 and output side slab waveguide 7
3 are radially arranged to pass through both centers of curvature. Thereby, the input side slab waveguide 71 and the output side slab waveguide 73 realize the same operation as the lens.

When the light including a plurality of wavelength components (λ ₁ , λ ₂ ,..., Λ _N ) enters the input waveguide 70, it spreads by diffraction in the input-side slab waveguide 71, and the plurality of array waveguides 74 ( 1) to 74 (N) are excited in the same phase. Each excitation light is transmitted to a corresponding one of the arrayed waveguides 74 (1) to 74 (1) to 7 (7).
When passing through 4 (N), a phase difference corresponding to the waveguide length difference is given, and reaches the output side slab waveguide 73. The plurality of light beams incident on the output side slab waveguide 73 interfere with each other by a lens action, and the plurality of output waveguides 72 (1)
The light is focused at one point on the side where .about.72 (N) is arranged, and diffracted in a direction in which the in-phase condition is satisfied. It should be noted that if the input side and the output side in the demultiplexing circuit shown in FIG. 7 are interchanged, the multiplexer included in the optical transceiver shown in FIG. 5 is realized.

FIG. 8 is a diagram showing a configuration example of a broadband light source included in the optical transceiver shown in FIG. In FIG. 8,
ASE (Amplified Spontaneous Em)
ission: amplified spontaneous emission light) An example of a light source is shown. This ASE light source is a broadband optical amplifier (Broadband).
The structure of the optical fiber amplifier is changed so that amplified spontaneous emission light can be emitted, and includes an optical fiber 80 for optical amplification. For details of the broadband optical amplifier, see, for example, “Broadband Optical Amplifier” by Haruki Ogoshi (IEICE Vol. 82 No. 7 pp.
718-724 July 1999). Optical fiber 80
A lens 81 is attached to one end of
At the other end, an FBG 82 for reflecting the excitation light is formed. On the left side of the lens 81, a laser oscillator 83 is arranged as an excitation light source. The light generated in the laser oscillator 83 enters the optical fiber 80 via the lens 81 and is amplified, and a part of the amplified light passes through the FBG 82 as spontaneous emission light. Note that a broadband fiber light source may be used instead of the ASE light source.

According to the present embodiment, when light including a plurality of wavelength components is supplied to the ultrasonic probe via the optical fiber, the light is demultiplexed in the optical waveguide connected to the optical fiber, and The light is incident on a plurality of FBGs having different reflection wavelength characteristics. These FBGs change the reflection wavelength based on the sound pressure of the applied ultrasonic waves and environmental fluctuations (for example, temperature changes). The light reflected by these FBGs is
The light is multiplexed in the optical waveguide and supplied to the optical fiber. Therefore, since a plurality of modulated lights are multiplexed,
The number of optical fibers connected to the ultrasonic probe can be reduced.

According to the present embodiment, a plurality of FBGs
By setting the spectrum of the light generated by the broadband light source so as to always include these reflection wavelengths even if the reflection wavelength characteristics of the FBG change, accurate adjustment of the conventional light source and multiple FBGs is not required. can do. And
Each incident position of the plurality of lights emitted from the demultiplexer is detected by a corresponding optical position detector, and based on a position signal output from each optical position detector, the signal processing unit Acquires sound pressure information of the ultrasonic wave received by the FBG. Therefore, even when there is an environmental change such as a temperature change,
The sound pressure of the ultrasonic wave received by the FBG can be accurately measured.

According to this embodiment, PZT or PVD
A two-dimensional sensor array is manufactured using FBG instead of a piezoelectric element made of F, and ultrasonic waves are detected using light. Therefore, the cost increases due to a decrease in yield, and the electrical impedance increases due to fine wiring. Therefore, the sensitivity can be improved, the broadband characteristics can be improved, and impedance-free can be realized.

[0044]

As described above, according to the present invention,
Ultrasonic waves can be reduced without reducing the number of optical fibers for transmitting input / output light of a plurality of ultrasonic detecting elements arranged two-dimensionally, and without requiring complicated adjustment in a light source and a plurality of ultrasonic detecting elements. An ultrasonic diagnostic apparatus capable of accurately measuring the sound pressure of an ultrasonic wave received by a detection element can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an ultrasonic diagnostic apparatus according to one embodiment of the present invention.

FIG. 2A is a perspective view showing a configuration of an ultrasonic probe included in the ultrasonic diagnostic apparatus shown in FIG. 1, and FIG.
It is a figure which shows the example of arrangement | positioning of the ultrasonic wave generation element and the ultrasonic detection element used for this ultrasonic probe, and (c) is a figure which shows another example of arrangement | positioning.

FIG. 3A is a perspective view showing a configuration of a one-dimensional receiving array unit included in the ultrasonic probe shown in FIG. 2, and FIG.
FIG. 3 is a projection view of the one-dimensional receiving array unit.

4 (a) to 4 (j) are diagrams showing a manufacturing process of the one-dimensional receiving array unit shown in FIG.

5A is a diagram for explaining a configuration of an optical transmission / reception unit included in the ultrasonic diagnostic apparatus shown in FIG. 1, and FIG.
FIG. 3 is a diagram illustrating spectral characteristics of a broadband light source included in the optical transmitting and receiving unit, and FIG. 3C is a diagram illustrating reflection wavelength characteristics of a plurality of fiber black gratings included in a corresponding one-dimensional receiving array unit.

FIG. 6 is a diagram for explaining a process of measuring a sound pressure of an ultrasonic wave in the ultrasonic diagnostic apparatus shown in FIG. 1;

FIG. 7 is a diagram illustrating a configuration example of a duplexer included in the optical transceiver illustrated in FIG. 5;

FIG. 8 is a diagram illustrating a configuration example of a broadband light source included in the optical transceiver illustrated in FIG. 5;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Ultrasonic probe 11 One-dimensional transmission array part 12 One-dimensional reception array part 14 Drive signal generation circuit 15 Optical transmission / reception part 17 Signal processing part 30 (1) -30 (N) Ultrasonic generation element 40 (1) -40 (N) Ultrasonic detection element 50 (1) to 50 (N) Optical waveguide 51 (1) to 51 (N) Fiber black grating 52 (1) to 52 (N-1) Slit 60 (1) to 60 (N) ) Optical position detector 61 Broadband light source 63 Circulator 66 Demultiplexer

Claims (9)

[Claims] 1. A light incident from a first end is converted into a plurality of second light.
And an optical waveguide that multiplexes the light returning from the plurality of second ends and supplies the combined light to the first end, and the plurality of optical waveguides of the optical waveguide. A plurality of ultrasonic detection elements formed at the second end and modulating and reflecting incident light based on the sound pressure of the applied ultrasonic wave, wherein the plurality of ultrasonic wave detection elements have different reflection wavelength characteristics of light from each other. An ultrasonic probe including an ultrasonic detection element, and a light transmitting and receiving unit that transmits and receives light between the ultrasonic probe, and a light source that generates light having a spectrum including a plurality of wavelength components. A demultiplexing unit that demultiplexes light containing a plurality of wavelength components for each predetermined wavelength component, and supplies light generated in the light source to the optical waveguide through an optical fiber, and supplies the light through the optical fiber. Switching means for outputting the divided light to the demultiplexing means, and the demultiplexing means The light transmitting and receiving means including a plurality of light position detecting means for detecting incident positions of a plurality of lights emitted from the light source; and a corresponding ultrasonic detecting element based on an output signal of each of the plurality of light position detecting means. And a signal processing unit for acquiring sound pressure information of the ultrasonic wave received by the ultrasonic diagnostic apparatus. 2. The signal processing means sets an output signal of each light position detecting means when each ultrasonic detecting element is not receiving an ultrasonic wave as a reference zero point signal, and outputs an output of each light position detecting means. 2. The ultrasonic diagnostic apparatus according to claim 1, wherein sound pressure information of the ultrasonic wave received by the ultrasonic detecting element is obtained based on a change amount of the signal from a reference zero point signal. 3. The ultrasonic probe includes a plurality of optical waveguides, the plurality of ultrasonic detection elements are arranged two-dimensionally, and a plurality of light transmitting / receiving units corresponding to the plurality of optical waveguides. The ultrasonic diagnostic apparatus according to claim 1 or 2, further comprising: 4. The ultrasonic diagnostic apparatus according to claim 1, wherein each of said plurality of ultrasonic detecting elements includes a fiber black grating. 5. The ultrasonic probe according to claim 1, wherein the ultrasonic probe further includes a plurality of ultrasonic generating elements for generating ultrasonic waves based on an input drive signal.
An ultrasonic diagnostic apparatus according to any of the preceding claims. 6. A light source comprising: a broadband light source; a broadband fiber light source; and an ASE (Amplified Spond).
The ultrasonic diagnostic apparatus according to any one of claims 1 to 5, further comprising one of a light source and a light source. 7. Each of the plurality of light position detecting means includes a plurality of one-dimensional array photodetectors in which a plurality of light receiving elements are arranged in a line, or a PSD (Position Sensitive Detector). The ultrasonic diagnostic apparatus according to claim 1. 8. The ultrasonic diagnostic apparatus according to claim 1, wherein said demultiplexing means includes an arrayed waveguide diffraction grating. 9. The ultrasonic diagnostic apparatus according to claim 1, wherein said switching means includes a circulator.