JP2002301076A - Ultrasonic probe, ultrasonic receiving device, and ultrasonic diagnostic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic probe dispensing with the electric wiring to a number of micro elements and never causing an increase in crosstalk or electric impedance. SOLUTION: This ultrasonic probe comprises an optical transmission path array containing a plurality of optical transmission paths having first end parts from which light is incident, and a plurality of ultrasonic detecting elements formed on the second end parts of the optical transmission paths to modulate the light incident through the respective optical transmission paths on the basis of an applied ultrasonic wave.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic probe and an ultrasonic receiver, and more particularly, to an ultrasonic probe and an ultrasonic receiver using such an ultrasonic probe and an ultrasonic receiver. The present invention relates to an ultrasonic diagnostic apparatus for performing medical diagnosis.

[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, 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, an element (vibrator or probe) for transmitting and receiving ultrasonic waves includes piezoelectric ceramics represented by PZT (lead zirconate titanate),
In general, a piezoelectric element such as PVDF (polymer piezoelectric element) is used, and a method of manufacturing a two-dimensional array using these elements is being studied. However, when the above-mentioned PZT or PVDF is used, fine processing of the element and wiring to a large number of fine elements are required, and it is difficult to achieve further miniaturization and element integration. Even if these problems are solved, there are problems such as an increase in crosstalk between elements, an increase in electrical impedance due to fine wiring, deteriorating the SN ratio, and easily breaking the electrode portion of the fine element. Therefore, it is difficult to realize a two-dimensional sensor array using PZT or PVDF.

For example, ULTRASONIC IMAG
ING 20, 1-15 (1998), E. of Duke University. D. "Progress i" by LIGHT et al.
nTwo-Dimensional Arrays f
or Real-TimeVolumetric Im
aging ”has been published. This article discloses a probe having a two-dimensional array of PZT ultrasonic sensors. However, at the same time, he states: "To obtain images of similar quality, the number of elements in a two-dimensional array is 128 × 128 = 16,38
4 is required. However, creating such a large number of RF channels is complex and costly and will be less promising in the near future. Also, it is very difficult to closely connect such a large number of elements. (Lines 14-18 on page 2) "

On the other hand, as an ultrasonic sensor that does not use a piezoelectric material such as PZT, a sensor using an optical fiber is also used. As such an optical fiber ultrasonic sensor, a fiber Bragg grating (abbreviated as FBG) is used.
(Underwater Acoustic Sens by TAKAHASHI et al. Of Defense University)
or with Fiber Bragg Grati
ng "OPTICALREVIEW Vol. 4, N
o. 6 (1997) p. 691-694) and those using a Fabry-Perot resonator (abbreviated as FPR) structure ("Fabrication" by UNO et al. Of Tokyo Tech).
and Performance of a Fiber
Optic Micro-Probe for Me
gahertz Ultrasonic Field
Measurements "T. IEEE Japan,
Vol. 118-E, No. 11, '98) have been reported, but these are all single sensors,
The construction of a sensor array has not yet been reported.

In the above-mentioned paper by TAKAHASHHI et al., It is described that a certain sensitivity can be obtained with respect to an ultrasonic wave in a relatively low frequency band of about 20 kHz.
No description is given of ultrasonic waves in the megahertz frequency band used in actual ultrasonic diagnosis. Therefore,
In order to put these sensors to practical use, it is necessary to confirm the operation for ultrasonic waves in a higher frequency band than the described example, and if necessary, to find conditions for obtaining good sensitivity in such a band. No.

[0009]

SUMMARY OF THE INVENTION In view of the above, the present invention provides a sensor array that does not require electrical wiring to a large number of microelements and does not cause crosstalk or increase in electrical impedance. It is an object of the present invention to provide a probe for ultrasonic waves. Further, the present invention provides an ultrasonic receiving apparatus capable of obtaining three-dimensional image data without scanning a probe. A further object of the present invention is to provide an ultrasonic diagnostic apparatus using such an ultrasonic probe and an ultrasonic receiving apparatus.

[0010]

In order to solve the above problems, an ultrasonic probe according to the present invention comprises an optical transmission line including a plurality of optical transmission lines into which light is incident from a first end. An array,
A plurality of ultrasonic detection elements are provided at the second ends of the plurality of optical transmission lines and modulate light incident through the respective optical transmission lines based on the applied ultrasonic waves.

Further, the ultrasonic receiving apparatus according to the present invention has
It comprises a plurality of ultrasonic detecting elements arranged in a dimension and modulating light based on applied ultrasonic waves, and a photodetector detecting light output from the plural ultrasonic detecting elements.

Further, the ultrasonic diagnostic apparatus according to the present invention is
A drive signal generation circuit that generates a drive signal for transmitting ultrasonic waves, an ultrasonic transmission unit that transmits ultrasonic waves toward the subject based on the drive signal output from the drive signal generation circuit, and An ultrasonic detection unit including a plurality of ultrasonic detection elements that modulate light based on ultrasonic waves, a photodetector that detects light output from the ultrasonic detection unit and generates a detection signal, and a photodetector. A signal processing unit for processing the output detection signal, and a control unit for controlling a transmission timing of the drive signal generation circuit and a reception timing of the signal processing unit are provided.

According to the present invention, since light is used for detecting ultrasonic waves, there is no need for electrical wiring to a large number of fine elements.
It does not cause crosstalk or increase in electrical impedance. Therefore, an ultrasonic probe and an ultrasonic receiving apparatus which are easy to manufacture and have a good SN ratio, and an ultrasonic diagnostic apparatus using them can be realized.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. The same components are denoted by the same reference numerals, and description thereof will be omitted.
FIG. 1 is a diagram showing in principle the ultrasonic receiving apparatus according to the first embodiment of the present invention. The ultrasonic receiver preferably has a light source 11 for generating a single-mode laser beam having a single wavelength of 500 to 1600 nm. The light generated from the light source 11 is incident on a duplexer 12 configured using a half mirror, an optical circulator, a polarizing beam splitter, or the like. The splitter 12 allows the incident light incident from the first direction to pass in the second direction, and passes the reflected light returning from the second direction in a third direction different from the first direction. Let it. In the present embodiment, a half mirror is used as the duplexer 12. The half mirror reflects the reflected light that passes through the incident light and returns from the direction opposite to the incident direction in a direction that forms an angle of approximately 90 ° with the incident direction.

The light that has exited the light source 11 and has passed through the splitter 12 enters an optical fiber array 13. The optical fiber array 13 is formed by arranging fine optical fibers 13a, 13b,... Two-dimensionally. These optical fibers are desirably single mode fibers. One light source may be provided for a plurality of optical fibers, or a plurality of light sources corresponding to a plurality of optical fibers may be provided. Further, the light emitted from one light source may be made to enter the plurality of optical fibers while being scanned in time series.

At the tip of the optical fiber array 13, an ultrasonic detecting element 14 is provided. Ultrasonic detection element 14
Are Fabry-Perot resonators (abbreviated as FPRs) formed at the tips of the optical fibers 13a, 13b,.
14a, 14b,...

A half mirror is formed at one end (the right side in the figure) of each FPR, and a total reflection mirror is formed at the other end (the left side in the figure). Light incident on the ultrasonic detecting element 14 is Is reflected by Since this total reflection surface is subjected to a geometric displacement by the ultrasonic wave applied to the ultrasonic detection element 14, the reflected light is modulated by this and enters the duplexer 12 again. The reflected light that has entered the duplexer 12 has its course changed, and then enters a photodetector 16 that includes a CCD, a photodiode (PD) array, or the like. here,
The reflected light may enter the photodetector 16 directly or through an optical fiber or the like, or an imaging system 15 such as a lens may be provided at the subsequent stage of the duplexer 12 so that the An image may be formed on the detector 16.

Next, the operation of the Fabry-Perot resonator constituting the ultrasonic detecting element 14 will be described in detail. The Fabry-Perot resonator forms a half-mirror at the end of a single-mode optical fiber by gold evaporation, etc., provides a cavity formed of polyester resin or the like at the tip, and forms a total reflection mirror at the tip by gold evaporation, etc. It was done. The member forming the cavity undergoes a geometric displacement due to the application of ultrasonic waves.

A detection light having a wavelength λ is made incident on the Fabry-Perot resonator from the half mirror side, and an ultrasonic wave is applied from the total reflection mirror side. Assuming that the length of the cavity is L and the refractive index is n, the reflection characteristic G _R of the Fabry-Perot resonator
Is represented by equation (1).

(Equation 1) Here, R is the reflectance of the half mirror, and G _S is the gain of a single pass. It can be seen from this equation that when the optical path length L of the cavity changes due to a change in the sound pressure of the ultrasonic wave, the intensity of the light reflected from the Fabry-Perot resonator changes.

In the reflection characteristic of the Fabry-Perot resonator, there is a gradient band where the reflectance greatly changes between a wavelength at which the reflectance is maximum and a wavelength at which the reflectance is minimum.
When an ultrasonic wave is applied while light having a wavelength in the tilt band is incident on the Fabry-Perot resonator, a change in the intensity of the reflected light according to the intensity of the ultrasonic wave can be observed. The intensity of the ultrasonic wave can be measured by converting the change in the intensity of the light. This Fabry-Perot resonator has a feature that the sensor has a high axial resolution because the sensor length is short.

Next, a second embodiment of the present invention will be described. FIG. 2 is a diagram conceptually showing an ultrasonic receiving apparatus according to a second embodiment of the present invention. This ultrasonic receiving apparatus is obtained by adding at least one of the optical amplifier 1 and the optical amplifier 2 to the ultrasonic receiving apparatus according to the first embodiment shown in FIG. The optical amplifier 1 is disposed between the light source 11 and the duplexer 12, amplifies the light incident from the light source 11, and emits the light to the duplexer 12. On the other hand, the optical amplifier 2 is disposed between the duplexer 12 and an imaging system 15 such as a lens, and amplifies the light incident from the duplexer 12 and emits the light to the imaging system 15. When the imaging system 15 is not used, the optical amplifier 2 is disposed between the splitter 12 and the photodetector 16, and the splitter 12
The light that has entered from above is amplified and emitted to the photodetector 16.

As an optical amplifier, for example, an optical fiber amplifier EDFA (Er) doped with erbium (Er) is used.
-Doped Optical Fiber Ampl
employer). This EDFA can increase the light intensity by about one to two orders of magnitude.

When such an optical amplifier is arranged between the light source 11 and the optical fiber array 13, the intensity of the incident light incident on the ultrasonic detecting element 14 is amplified. When the optical amplifier is disposed between the optical fiber array 13 and the photodetector 16, the intensity of the incident light incident on the ultrasonic detecting element 14 does not change, but the reflected light incident on the photodetector 16 does not change. Is amplified. In this case, the intensity change of the reflected light modulated by the received ultrasonic wave is also amplified.

In any case, by amplifying the intensity in the light state, the amount of reflected light incident on the photodetector 16 increases, so that the influence of electrical noise on the photodetector 16 is reduced, The S / N ratio of the sound wave receiving device can be improved. Furthermore, when both are used in combination, it is possible to further improve the SN ratio.

Further, according to the configuration of the present embodiment, the S / N ratio in the ultrasonic receiving apparatus is improved.
It can also be used to relax the specifications of the filter characteristics of the ultrasonic detection element 14. For example, as shown in FIG. 3, it is possible to make the inclination of the reflection characteristic of the ultrasonic detection element 14 gentle. In that case, the manufacture of the ultrasonic detection element 14 becomes easy. Further, since the linear region of the reflection characteristic is widened, even if the wavelength λ _{0 of the} incident light fluctuates somewhat with the temperature, the ultrasonic wave can be detected accurately.

Next, an ultrasonic receiving apparatus according to a third embodiment of the present invention will be described. FIG. 4 is a diagram illustrating in principle a part of the ultrasonic receiving apparatus according to the third embodiment of the present invention. This ultrasonic receiving apparatus uses a fiber Bragg grating (abbreviated as FBG) instead of the Fabry-Perot resonator in the first embodiment. That is, in the third embodiment, an ultrasonic detection element 17 having a Bragg grating structure is provided at the tip of the same optical fiber array 13 as shown in FIG. The ultrasonic detecting element 17 includes optical fibers 13a, 13b,.
Bragg grating portions (FBG in the present embodiment) 17a, 17b,
..

The Bragg grating portion is formed by alternately stacking two types of material layers (light propagation media) having different refractive indices at a pitch satisfying the Bragg reflection condition.
It has higher reflectance and sharper wavelength dependence than a single-layer Fabry-Perot resonator. FIG. 4 shows a material layer A having a refractive index n ₁ and a material layer B having a refractive index n ₂ . Assuming that the pitch (interval) of the periodic structure of these layers is d and the wavelength of the incident light is λ, the Bragg reflection condition is expressed by equation (2). Here, m is an arbitrary integer. 2d · sin θ = mλ (2) where θ is an incident angle measured from the incident surface, and θ = π /
If it is 2, it becomes like Formula (3). 2d = mλ (3) The Bragg grating section selectively reflects light of a specific wavelength that satisfies the Bragg reflection condition, and transmits light of other wavelengths.

When an ultrasonic wave is propagated through the Bragg grating, the Bragg grating is distorted and the pitch d of the periodic structure changes, so that the wavelength λ of the light to be selectively reflected changes. In the reflection characteristic of the Bragg grating portion, there is a gradient band in which the reflectance changes before and after the center wavelength having the highest reflectance (lowest transmittance), and the detection light having the center wavelength falls within the range of this gradient band. The ultrasonic wave is applied while being incident on the part. Then, a change in the intensity of the reflected light (or transmitted light) according to the intensity of the ultrasonic wave can be observed. The intensity of the ultrasonic wave can be measured by converting the change in the intensity of the light.

Here, the Bragg grating section has high sensitivity and is easy to make, and in general, it is possible to divert a consumer product. However, it cannot be used as it is as a sensor having high sensitivity as in ultrasonic diagnosis. For example, if a Bragg grating unit used in a normal market is used, 20 kHz
It has been confirmed that in higher frequency bands, the sensitivity to ultrasonic waves incident from the axial direction decreases.
In addition, the length of the ultrasonic sensitive part (length of the Bragg grating part) is expressed by (ultrasonic wavelength) = (sound velocity in the Bragg grating part) / (frequency of ultrasonic wave) Ultrasonic wave in the Bragg grating part If the wavelength is larger than approximately ／, the detected waveform is distorted to the lower frequency side as compared with the waveform of the actually received ultrasonic wave, and the sensitivity of the sensor is lowered. This is because when the length of the Bragg grating part is larger than half the ultrasonic wavelength in the Bragg grating part, a part where the phase of expansion and contraction is inverted in the Bragg grating part in the process of transmitting the ultrasonic wave through the Bragg grating part occurs Therefore, it is considered that the displacement of these portions is offset.

In order to avoid such a phenomenon, the length of the Bragg grating should be approximately 概略 or less, preferably about half, of the ultrasonic wavelength in the Bragg grating. For example, when the frequency of the ultrasonic wave to be detected is 3.5 MHz and the sound speed in the material of the Bragg grating portion is 5500 m / s, the wavelength λ _S of the ultrasonic wave propagating through the Bragg grating portion is calculated as follows. Is done. λ _S = 5500 / (3.5 × 10 ⁶ ) = 1571.4 (μm) Accordingly, the upper limit of the length of the Bragg grating portion is calculated as follows. 1571 × (3/4) = 117
8.5 (μm) From this, if the length of the Bragg grating portion is 1178.5 μm or less, the influence of the reversal of the expansion / contraction phase in the Bragg grating portion is suppressed, and the sensitivity required for detecting the ultrasonic wave is obtained. Can be.

Next, an ultrasonic receiving apparatus according to a fourth embodiment of the present invention will be described. In the present embodiment, an optical waveguide having a Bragg grating structure is used as an ultrasonic detection element. FIG. 5 shows in principle the configuration of the ultrasonic receiving apparatus according to the present embodiment. As shown in FIG. 5, a plurality of optical waveguides 51a, 51
are formed at the tip of the core, and Bragg grating portions 52a, 52b,.
・ Is formed. The light emitted from the light source 11 passes through the duplexer 12, and enters each of the optical waveguides 51a, 51b,. In each optical waveguide, light is modulated by the structural change of the Bragg grating portion formed at the tip thereof by the ultrasonic wave. The light reflected by each Bragg grating section is redirected in the demultiplexer 12, and the respective optical waveguides 51a, 51b,.
Are incident on the photodetectors 16a, 16b,. As described above, by detecting the change in the light intensity in the photodetectors 16a, 16b,..., The intensity of the ultrasonic wave transmitted to the corresponding optical waveguide can be measured. In this embodiment, as in the case of the third embodiment, the length of the Bragg grating formed in the optical waveguide is ３ or less of the wavelength of the ultrasonic wave propagating through the Bragg grating. It is desirable.

Next, a fifth embodiment of the present invention will be described.
This will be described with reference to FIGS. In the present embodiment, an optical waveguide 53 having a Bragg grating structure is used as an ultrasonic detection element, and a plurality of lights having different wavelengths are multiplexed and used as detection light. FIG.
7 shows in principle the configuration of the ultrasonic receiving apparatus according to the present embodiment, FIG. 7 shows the structure of the ultrasonic detecting section 50 shown in FIG. 6, and FIG. 8 shows the components shown in FIG. The structure of the wave device 41 is shown.

As shown in FIG. 6, this ultrasonic receiving apparatus receives light from the light source 8, an optical circulator 113, an ultrasonic detecting section 50 including an optical waveguide having a Bragg grating structure, and an ultrasonic detecting section 50. A demultiplexer 41 for demultiplexing the detection light, photodetectors 16a, 16b,... For detecting the intensity of the demultiplexed light, and these devices (uni).
t) interconnecting optical fibers 56, 57, 58, 5
9a, 59b,... In the present embodiment, a broadband light source (broadband light source) 8 that generates broadband light (broadband light) 8 is used as a light source, and an optical circulator 113 that switches the traveling direction of light according to the incident direction is used as a demultiplexer. Used.

In FIG. 6, the light emitted from the light source 8 is incident on the optical circulator 113 via the optical fiber 57, and is further transmitted via the optical fiber 56 to the ultrasonic detecting unit 50.
Incident on. Here, referring to FIG. 7, the ultrasonic detecting unit 50 has a plurality of inverted L-shaped optical waveguides 53a, 53b,... Formed on the substrate 55 and having different waveguide lengths. These optical waveguides 53a, 53b,... Are arranged such that their cross sections are arranged in one line. Also,
Are formed at the tips of the optical waveguides 53a, 53b,....

In this embodiment, each black
Pitch of periodic structure of each layer constituting grating section
Is the reflection wavelength for a specific wavelength based on equation (3).
The characteristics are determined to be large. That is,
Of the periodic structure of each layer constituting the grating section 52a.
The pitch d is determined based on the equation (3) so that the black wavelength is λ. ₁
It is determined to be. Also, Bragg grating
The pitch d of the periodic structure of each layer constituting the tapered portion 52b is given by the following equation
Based on (3), the black wavelength is λ_Two(≠ λ₁) Becomes
It is decided as follows. Remaining Bragg grating part 5
The same applies to 2c, 52d,... Therefore,
Of the Bragg grating portions 52a, 52b,...
The emission wavelength characteristics are different from each other. Multiple Bragg Gres
, The ultrasonic waves are applied to the driving parts 52a, 52b,...
Then, it expands and contracts in the sound pressure direction of the ultrasonic wave. As a result,
Each of the Bragg grating sections 52a, 52b,.
.. The pitch d of the periodic structure of each layer constituting
Change each black wavelength. Therefore, the reception of ultrasound
In each of the Bragg grating sections 52a, 52
The light incident on b,... is based on the applied ultrasonic wave.
Modulated. In the present embodiment, the third actual
As in the case of the embodiment, a shape is formed at the tip of each optical waveguide.
The length of the Bragg grating to be formed depends on the optical waveguide
Is preferably less than or equal to ／ of the wavelength of the ultrasonic wave propagating through
New

The end of the optical waveguide 52a is connected to the optical fiber 5
6 is connected. A gap 54a is formed between the end of the optical waveguide 53a and the end of the optical waveguide 53b, and the gap 54a functions as a beam splitter. Similarly, the end of the optical waveguide 53b and the optical waveguide 5
An air gap 54b that functions as a beam splitter is formed between the end 3c and the end 3c. The remaining optical waveguide 53c,
The same applies to 53d,... In this embodiment, by connecting the plurality of optical waveguides 53a, 53b,... In this manner, the planar lightwave circuit (PL
C: Planar Lightwave Circuit).

Here, the operation of the ultrasonic detector 50 shown in FIG. 7 will be described. A plurality of wavelength components (λ ₁ , λ ₂ ,.
· Light L _MUL containing a lambda _N), when supplied to the ultrasonic detecting unit 50, is demultiplexed in each pass through a plurality of air gaps 54a, 54b, a .... Light L incident on the optical waveguide 53a
₁ (wavelength: λ ₁ ) is reflected by the Bragg grating section 52a toward the optical waveguide 53a, and is modulated into light L ₁ ′ based on the ultrasonic wave applied to the Bragg grating section 52a. The light L ₂ (wavelength: λ ₂ ) incident on the optical waveguide 53 _b is transmitted to the Bragg grating 52.
b, is reflected toward the optical waveguide 53b and is modulated into light L ₂ ′ based on the ultrasonic wave applied to the Bragg grating section 52b. Remaining light L included in light L _MUL
The same applies to ₃ (wavelength: λ ₃ ), L ₄ (wavelength: λ ₄ ,....
a, 52b,... outgoing light L ₁ ′, L ₂ ′,.
Are sequentially combined in the corresponding gaps 54a, 54b,... And enter the optical fiber 56.

Referring again to FIG.
Incident on the optical fiber circulator 113, the traveling direction of the light is changed by the optical circulator 113,
Incident on. The demultiplexer 41 converts the light L _MUL ′ incident from the optical fiber 58 into a plurality of lights L ₁ ′ for each predetermined wavelength component,
Demultiplex to L ₂ ′,. The demultiplexer 41 includes a plurality of photodetectors 16a, 16b having different wavelength bands of light to be detected.
... correspond to the corresponding optical fibers 59a, 59b, ...
Connected through. A plurality of photodetectors 16a, 16
are the corresponding optical fibers 59a, 59b,.
.. Detected by detecting light L ₁ ′, L ₂ ′,... Incident on the Bragg gratings 52 a, 52 b,. The intensity of the sound wave can be detected.

Referring to FIG. 8, in the present embodiment, an arrayed waveguide grating (AWG: Arrayed-Wavelength Grade), which is a type of planar lightwave circuit, is used as a demultiplexer.
(Ting) is used. This demultiplexing circuit includes an input-side slab waveguide 72 to which one input waveguide 71 is connected, and a plurality of output waveguides 73a, 73b,.
Are connected to the output-side slab waveguide 74 to which a plurality of arrayed waveguides 75a and 75 having a constant waveguide length difference are provided.
are connected by b,...

The input side slab waveguide 72 is connected to the input waveguide 7.
The output-side slab waveguide 74 has a sector shape having the ends as the centers of curvature, and the output-side slab waveguide 74 has the ends as the center of curvature. The plurality of arrayed waveguides 75a, 75b,... Are radially arranged such that their optical axes pass through the centers of curvature of both the input slab waveguide 72 and the output slab waveguide 74. Thereby, the input side slab waveguide 72 and the output side slab waveguide 74 realize the same operation as the lens.

A plurality of wavelength components (λ ₁ , λ ₂ ,...,
When the light L _MUL ′ containing λ _N ) enters the input waveguide 71, it spreads by diffraction in the input side slab waveguide 72, and excites the plurality of arrayed waveguides 75 a, 75 b,. When the respective excitation lights pass through the corresponding arrayed waveguides 75a, 75b,..., They are given a phase difference corresponding to the waveguide length difference, and reach the output side slab waveguide 74. The plurality of lights incident on the output side slab waveguide 74 are condensed at one point on the side where the plurality of output waveguides 73a, 73b,. Diffracts in the direction that holds. In addition,
By switching the input side and the output side in the demultiplexing circuit shown in FIG. 8, it can be used as a multiplexer.

In the present embodiment, a broadband light source is used as a light source. Alternatively, a plurality of laser oscillators having different wavelengths may be used, and a light obtained by multiplexing and multiplexing emitted laser lights may be used. good. In this case, for example, the duplexer shown in FIG. 8 may be used as a multiplexer.

Next, an ultrasonic receiving apparatus according to a sixth embodiment of the present invention will be described. FIG. 9 is a diagram illustrating in principle the ultrasonic receiving apparatus according to the present embodiment. The ultrasonic receiving apparatus according to the present embodiment is obtained by changing the light source in the first to fifth embodiments, and uses the light generated from the broadband light source by narrowing the band using a narrow band filter. In the present embodiment, an example in which the present invention is applied to an ultrasonic receiving apparatus according to a third embodiment of the present invention will be described.

As the broadband light source, for example, ASE (Amplify) that emits amplified spontaneous emission light is used.
(ed Spontaneous Emission) light source 9 is used. The ASE light source 9 includes a broadband optical amplifier (B
loadband Optical Fiber Am
(Plier) is changed so that amplified spontaneous emission light can be generated. For details of the broadband optical amplifier, for example, see “Broadband Optical Amplifier” by Haruki Ogoshi (IEICE Vol. 82, No. 7,
pp. 718-724, July 1999).

As shown in FIG. 10, the ASE light source 9 includes an optical fiber 94 for amplifying light. Optical fiber 94
A lens 91 is attached to one end, and an FBG 92 for reflecting excitation light is formed at the other end. On the left side of the lens 91 in the figure, a laser oscillator 93 is arranged as an excitation light source. The light generated in the laser oscillator 93 enters the optical fiber 94 via the lens 91 and is amplified. A part of the amplified light passes through the FBG 92 as spontaneous emission light. The spontaneous emission light generated by the ASE light source 9 has a broad spectrum as shown in FIG. As a broadband light source, AS
A broadband fiber light source may be used instead of the E light source.

Referring again to FIG. 9, the light generated by the ASE light source 9 is split into a splitter 10 using a half mirror, an optical circulator, a polarizing beam splitter, or the like.
Incident on. The splitter 10 allows light incident from the first direction to pass in the second direction, and allows reflected light returning from the second direction to pass in a third direction different from the first direction. . In the present embodiment, a half mirror is used as the duplexer 10.

The light exiting the ASE light source 9 and passing through the splitter 10 enters the optical fiber array 20. The optical fiber array 20 is an array of fine optical fibers arranged two-dimensionally. In addition, one A for a plurality of optical fibers
An SE light source may be provided, or a plurality of ASE light sources corresponding to a plurality of optical fibers may be provided. Further, the light generated by one ASE light source may be incident on a plurality of optical fibers while being scanned in time series.

The front end of the optical fiber array 20 has an FBG
Is provided. The light that has entered the optical fiber array 20 is reflected by the FBG of the narrow band filter 19 and enters the duplexer 10 again. The spontaneous emission light generated from the ASE light source 9 passes through the narrow band filter 19 to have a spectrum as shown in FIG. 12, and the band is narrowed around the wavelength λ ₀ . The light reflected by the narrow band filter 19 enters the duplexer 10 again. The light that has entered the duplexer 10 has its course changed and enters the duplexer 12. The light that has passed through the splitter 12 enters the optical fiber array 13. An ultrasonic detection element 17 is provided at the tip of the optical fiber array 13. The ultrasonic detecting element 17 is composed of FBGs formed at the tips of a plurality of optical fibers, respectively. Light incident on the optical fiber array 13 is reflected by the FBG of the ultrasonic detection element 17. This F
Since the BG undergoes a geometric displacement due to the ultrasonic wave applied to the ultrasonic detecting element 17, the reflected light is modulated by this and enters the duplexer 12 again.

The reflected light that has entered the duplexer 12 has its course changed and enters the photodetector 16. The reflected light may enter the photodetector 16 directly or through an optical fiber or the like, or an imaging system 15 such as a lens may be provided at the subsequent stage of the duplexer 12 so that the reflected light is transmitted through the imaging system 15. An image may be formed on the detector 16. Further, similarly to the second embodiment, it is disposed between the duplexer 12 and an imaging system 15 (or a photodetector 16) such as a lens, and amplifies the light incident from the duplexer 12 to form a light. An optical amplifier that emits light to the image system 15 (or the photodetector 16) may be provided.

Here, in FBG, the center wavelength of reflected light changes at a rate of 0.01 nm / ° C. due to a change in temperature.
Therefore, when a light source that generates laser light of a single wavelength is used, there has been a problem that the sensitivity of the ultrasonic detection element 17 constituted by the FBG greatly changes due to a change in temperature.

However, in the present embodiment, A
Spontaneous emission light generated from the SE light source 9 is filtered by the narrow band filter 1.
By narrowing the band by using 9, a band close to a single-wavelength laser beam is secured, and a change in sensitivity of the ultrasonic receiving apparatus due to a change in temperature is reduced.

That is, in the present embodiment, the narrow band filter 19 and the ultrasonic detecting element 17 are formed of the same material, and the narrow band filter 19 and the ultrasonic detecting element 17 are thermally coupled. I have. The thermal coupling is realized by, for example, coupling the narrow band filter 19 and the ultrasonic detection element 17 with a material having high thermal conductivity, or bringing the narrow band filter 19 and the ultrasonic detection element 17 into physical proximity. Is done. Or
Thermal coupling can also be achieved by arranging a heat pipe around the narrow band filter 19 and the ultrasonic detection element 17. When a heat pipe is used, a fluid that conducts heat by convection is sealed in the heat pipe.

Thus, the FBG of the narrow band filter 19
And the FBG of the ultrasonic detecting element 17 have substantially the same temperature. Therefore, even if the reflection characteristic of the ultrasonic detecting element 17 shifts due to the temperature, the wavelength of the light incident on the ultrasonic detecting element 17 also shifts. Thus, a change in the sensitivity of the ultrasonic receiving apparatus can be reduced.

For example, in the initial state, as shown in FIG. 13, the output light of the narrow band filter 19, that is, the center wavelength of the light incident on the ultrasonic detecting element 17 is λ ₀ , It is assumed that the reflection characteristic is in a state (center wavelength λ ₁ ) suitable for detecting a change in the wavelength of the incident light having the center wavelength λ ₀ . Even if the temperature of the ultrasonic detecting element 17 rises with time and the reflection characteristic of the ultrasonic detecting element 17 changes to the state of the center wavelength λ ₁ ′ as shown in FIG. Since it changes to λ ₀ ′, a state suitable for detecting a change in the wavelength of the incident light can be maintained.
Here, the shift amount of the center wavelength of the ultrasonic detecting element 17 (λ
₁ 'and 1-? _1), the shift amount of the center wavelength of the output light of the narrow-band filter 19 (lambda _0' and the 1-? _0), substantially equal.

Next, an ultrasonic receiving apparatus according to a seventh embodiment of the present invention will be described. FIG. 15 is a diagram conceptually showing a part of the ultrasonic receiving apparatus according to the seventh embodiment. An ultrasonic detecting element 18 shown in FIG. 15 includes a Fabry-Perot resonator (FPR) 14 in the first embodiment,
The Bragg grating unit (F in the third embodiment)
BG) 17. That is, the optical fiber 1
FBG17 is formed at the tip of No.3, and FPR17 is further
14 are formed. Thus, light not reflected by the FBG 17 can be reflected by the FPR 14. Note that, in the present embodiment, unlike the first embodiment, it is suitable to use multi-wavelength or wide-band laser light.

As for the structure of the ultrasonic probe included in the ultrasonic receiving apparatus described in some embodiments, see FIGS. 16 (a) to 16 (c) and FIG. I will explain while. As shown in FIG.
An optical fiber array 13 provided with an ultrasonic detection element 14 or 17 or 18 is housed in a housing 21. The interval between the ultrasonic detection elements 14 or 17 or 18,
In order to suppress side lobes, it is desirable to set the wavelength to not more than half the wavelength of the received ultrasonic wave. The arrangement of the ultrasonic detecting elements 14 or 17 or 18 may be set at the positions of the vertices of a continuous square as shown in FIG. 16B, or the density of the ultrasonic detecting elements may be increased in FIG. (C) as shown in FIG.

It is desirable to provide an acoustic matching layer 22 between the ultrasonic detecting element 14 or 17 or 18 and the housing 21 in order to match acoustic impedance. The acoustic matching layer 22 can be made of Pyrex glass (Pyrex is a registered trademark) that easily transmits ultrasonic waves, epoxy resin containing metal powder, or the like. Further, it is desirable to provide an acoustic lens material 23 such as silicone rubber on the surface of the housing 21 also to protect the ultrasonic detecting element. Further, it is desirable that the space between the adjacent optical fibers is filled with the sound absorbing material 24 in order to reduce the crosstalk of the ultrasonic waves. As the sound absorbing material 24, epoxy resin containing metal powder, rubber containing ferrite powder, or the like is suitable. The optical fiber array 13 is hardened with the resin 25 except for the vicinity of the portion where the ultrasonic detection element is provided.

As shown in FIG. 17, in order to two-dimensionally arrange an ultrasonic detecting element including an optical waveguide having a Bragg grating structure, a plurality of substrates 55 on which the optical waveguide is formed are connected in parallel. Should be fixed to At this time, the respective substrates may be arranged via the sound absorbing material 24 or the like.

Next, an ultrasonic diagnostic apparatus according to the first embodiment of the present invention will be described with reference to FIG.
In this ultrasonic diagnostic apparatus, the above-described ultrasonic receiving apparatus is used as an ultrasonic detecting section (sensor), and an ultrasonic transmitting section is separately provided. As shown in FIG. 18, the ultrasonic diagnostic apparatus includes a driving signal generating circuit 30 that generates a driving signal, and an ultrasonic transmitting unit 40 that transmits an ultrasonic wave based on the driving signal. The ultrasonic transmission unit 40
It is composed of a vibrator or a probe (one-dimensional array) using a piezoelectric element such as ZT or PVDF. The ultrasonic waves transmitted toward the subject are reflected from the subject and received by the ultrasonic detecting unit (sensor) 50. The sensor 50 includes an optical fiber array, an ultrasonic detection element, and the like.

The ultrasonic diagnostic apparatus includes the light source 11, the duplexer 12, the imaging system 15, and the photodetector 16 as described above. The detection signal output from the photodetector 16 is input to a signal processing unit 61 included in the signal processing unit 60, and is further converted into a digital signal by an A / D converter 62.

A primary storage unit 80 is connected to the A / D converter 62, and the acquired plural pieces of surface data are stored in the primary storage unit 80. The image processing unit 90 reconstructs two-dimensional data or three-dimensional data based on the data. The reconstructed data undergoes processing such as interpolation, response modulation processing, and gradation processing, and is displayed on the image display unit 100. Further, the data processed by the image processing unit 90 is stored in the secondary storage unit 110.

The timing control section 70 controls the drive signal generation circuit 30 so as to generate a drive signal at a predetermined timing, and takes in a detection signal output from the photodetector 16 after a lapse of a predetermined time from the transmission time. The signal processing unit 61 is controlled as described above. Here, the following three types of transmission methods of the ultrasonic wave in the drive signal generation circuit 30 and the ultrasonic transmission unit 40 can be considered, and the data acquisition time and the data content in the signal processing unit 61 are changed accordingly. It's changing.

(1) A case where an ultrasonic wave is narrowed down into a pencil beam and transmitted, as shown in FIG. 19, a transmission wave is narrowed down spatially into a pencil beam by an ultrasonic wave transmitting unit 40, and an object is focused on a certain plane. If the sensor 50 scans two-dimensionally and takes in a detection signal after a lapse of a predetermined time from transmission, information at each point on the surface can be obtained.
If this operation is performed within a section existing at a certain depth from the sensor 50, cross-section information at a certain depth can be obtained. By repeating this process while changing the capturing time at each pencil beam position, a plurality of cross-sectional images having different depths can be obtained. The sample data thus obtained is focused on both transmission and reception and can be displayed as it is as three-dimensional data.

(2) When Ultrasonic Waves are Narrowed down and Transmitted As shown in FIG. 20, the transmission wave generated from the ultrasonic wave transmitting section 40 is narrowed down into a planar shape using an acoustic lens, and If a detection signal is taken in after a predetermined time has elapsed from the transmission, one-dimensional line information at a certain depth can be acquired collectively. However, since the information of each point also contains information of other points in the region where the ultrasonic wave is applied, the wavefront synthesis (so-called aperture synthesis) is performed based on the detection signal whose capture time is shifted. It is necessary to obtain a display image by reconstructing the focused data.

(3) Transmission of Ultrasonic Wave as Plane Wave Further, as shown in FIG. 21, the ultrasonic wave transmitting section 40 transmits a transmission wave as a plane wave, and the sensor 50 takes in a detection signal after a lapse of a predetermined time from the transmission. By doing so, it is possible to collectively acquire two-dimensional surface information at a certain depth. If this step is repeated while changing the capturing time, a plurality of cross-sectional images having different depths can be obtained. However, since the information of each point also contains information of other points in the region where the ultrasonic wave is applied, the wavefront synthesis (so-called aperture synthesis) is performed based on the detection signal whose capture time is shifted. It is necessary to obtain a display image by reconstructing the focused data.

Next, an ultrasonic diagnostic apparatus according to a second embodiment of the present invention will be described with reference to FIG.
In the present embodiment, the ultrasonic detecting section 50 constituted by the ultrasonic receiving apparatus as described above is used as the ultrasonic transmitting / receiving section 120 in combination with the ultrasonic transmitting section 40. Other points are the same as those of the ultrasonic diagnostic apparatus according to the first embodiment.

[0067]

As described above, according to the present invention, light is used for one-dimensional or two-dimensional detection of ultrasonic waves.
There is no need for electrical wiring to a large number of microelements, and there is no increase in crosstalk or electrical impedance. Therefore, it is possible to realize an ultrasonic receiving apparatus and an ultrasonic receiving apparatus which are easy to manufacture and have a good SN ratio, and an ultrasonic diagnostic apparatus using them.

[Brief description of the drawings]

FIG. 1 is a diagram showing in principle an ultrasonic receiving apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating in principle an ultrasonic receiving apparatus according to a second embodiment of the present invention.

FIG. 3 is a diagram illustrating an example of a reflection characteristic of an ultrasonic detecting element in an ultrasonic receiving device according to a second embodiment of the present invention.

FIG. 4 is a diagram showing in principle a part of an ultrasonic receiving apparatus according to a third embodiment of the present invention.

FIG. 5 is a diagram conceptually showing an ultrasonic receiving apparatus according to a fourth embodiment of the present invention.

FIG. 6 is a diagram conceptually showing an ultrasonic receiving apparatus according to a fifth embodiment of the present invention.

FIG. 7 is a diagram illustrating a structure of an ultrasonic detection unit illustrated in FIG. 6;

FIG. 8 is a diagram showing the structure of the duplexer shown in FIG.

FIG. 9 is a diagram conceptually showing an ultrasonic receiving apparatus according to a sixth embodiment of the present invention.

FIG. 10 shows an AS used in the sixth embodiment of the present invention.
It is a figure which shows E light source in principle.

11 is a diagram showing a spectrum of spontaneous emission light generated by the ASE light source of FIG.

FIG. 12 is a diagram showing a spectrum of output light of a narrow band filter used in a sixth embodiment of the present invention.

FIG. 13 is a diagram illustrating a relationship (initial state) between incident light and reflection characteristics of an ultrasonic detection element according to a sixth embodiment of the present invention.

FIG. 14 is a diagram illustrating a relationship (after a temperature rise) between incident light and a reflection characteristic of an ultrasonic detection element according to a sixth embodiment of the present invention.

FIG. 15 is a view principally showing a part of an ultrasonic receiving apparatus according to a seventh embodiment of the present invention.

FIGS. 16 (a) to 16 (c) are diagrams showing the structure of an ultrasonic probe included in the ultrasonic receiving apparatus according to the present invention.

FIG. 17 is a diagram showing a structure of an ultrasonic probe included in the ultrasonic receiving apparatus according to the present invention.

FIG. 18 is a block diagram showing an ultrasonic diagnostic apparatus according to the first embodiment of the present invention.

FIG. 19 is a diagram for explaining a detection method in a case where ultrasonic waves are narrowed down into a pencil beam and transmitted.

FIG. 20 is a diagram for describing a detection method in a case where ultrasonic waves are narrowed down and transmitted in a planar shape.

FIG. 21 is a diagram for explaining a detection method when transmitting an ultrasonic wave as a plane wave.

FIG. 22 is a block diagram illustrating an ultrasonic diagnostic apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

1, 2 Optical amplifier 8 Broadband light source (broadband light source) 9 ASE light source 10, 12, 41 Demultiplexer 11 Light source 13, 20 Optical fiber array 13a, 13b, ... Optical fiber 14, 17, 18 Ultrasonic detection element 14a , 14b, ... Fabry-Perot resonator (F
PR) 15 Imaging system 16, 16a, 16b,... Photodetector 17a, 17b,... Bragg grating (FBG) 19 Narrow band filter 21 Housing 22 Acoustic matching layer 23 Acoustic lens material 24 Sound absorbing material 25 Resin 30 drive signal generation circuit 40 ultrasonic transmission section 50 ultrasonic detection section (sensor) 51a, 51b, ..., 53, 53a, 53b, ...
Optical waveguides 52a, 52b,... Bragg gratings 54a, 54b,... Air gap 55 Substrates 56 to 58, 59a, 59b,. Converter 70 Timing control unit 71 Input waveguide 72 Input side slab waveguide 73a, 73b,... Output waveguide 74 Output side slab waveguide 75a, 75b,... Array waveguide 80 Primary storage unit 90 Image processing Unit 91 lens 92 fiber Bragg grating (FBG) 93 laser oscillator 94 optical fiber 100 image display unit 110 secondary storage unit 113 optical circulator 120 ultrasonic transmission / reception unit

Continued on front page F term (reference) 2G047 AC13 BA03 BA07 BC13 CA01 CA04 DB02 DB12 EA10 EA14 GA01 GB02 GD01 GF01 4C301 AA03 BB13 BB22 EE11 EE15 GA01 GB09 GB20 GB27 JA03 5D019 BB02 BB10 BB19 FF04 GG01

Claims (30)

[Claims] 1. An optical transmission line array including a plurality of optical transmission lines into which light is incident from a first end, and an ultrasonic wave formed and applied at a second end of the plurality of optical transmission lines. And a plurality of ultrasonic detecting elements for modulating light incident through each of the optical transmission paths based on the above. 2. The ultrasonic probe according to claim 1, wherein the optical transmission line array includes an optical fiber array having a plurality of optical fibers. 3. The ultrasonic probe according to claim 2, wherein the optical fiber is a single mode fiber. 4. The ultrasonic probe according to claim 1, wherein said optical transmission line array includes a plurality of optical waveguides formed on a substrate. 5. The ultrasonic probe according to claim 1, wherein each of the plurality of ultrasonic detection elements has a Fabry-Perot resonator structure. 6. The ultrasonic probe according to claim 1, wherein each of the plurality of ultrasonic detection elements has a Bragg grating structure. 7. The ultrasonic probe according to claim 1, wherein each of the plurality of ultrasonic detection elements has both a Fabry-Perot resonator structure and a Bragg grating structure. . 8. An ultrasonic sensitive part included in the ultrasonic detection element, wherein the ultrasonic sensitive part is 3/3 of the wavelength of the ultrasonic wave propagating through the ultrasonic sensitive part.
The ultrasonic probe according to any one of claims 1 to 7, having a length of 4 or less. 9. The ultrasonic probe according to claim 1, further comprising at least one of an acoustic matching layer, an acoustic lens, and a sound absorbing material. 10. A plurality of ultrasonic detecting elements arranged two-dimensionally and modulating light based on applied ultrasonic waves, and a photodetector detecting light output from the plural ultrasonic detecting elements. An ultrasonic receiving device comprising: 11. The ultrasonic receiving apparatus, comprising: a first end on which light is incident; and a second end on which the ultrasonic detecting element is formed.
The ultrasonic receiving apparatus according to claim 10, further comprising an optical fiber array including a plurality of optical fibers each having an end. 12. A plurality of optical waveguides, wherein the ultrasonic receiving device is formed on a substrate and has a first end on which light is incident and a second end on which the ultrasonic detecting element is formed. The ultrasonic receiving apparatus according to claim 10, further comprising a wave path. 13. The ultrasonic receiving apparatus according to claim 10, further comprising an optical amplifier that amplifies light generated from a light source and enters the plurality of ultrasonic detecting elements. 14. The ultrasonic receiving apparatus according to claim 10, further comprising an optical amplifier that amplifies light output from the plurality of ultrasonic detecting elements and makes the light incident on the photodetector. 15. The ultrasonic receiving apparatus according to claim 10, further comprising a light source that generates a single mode laser light having a wavelength of 500 to 1600 nm. 16. Each of the plurality of ultrasonic detection elements includes:
10. A Fabry-Perot resonator structure.
The ultrasonic receiver according to any one of claims 5 to 10. 17. Each of the plurality of ultrasonic detection elements,
2. The device has a Bragg grating structure. 3.
The ultrasonic receiver according to any one of claims 5 to 10. 18. Each of the plurality of ultrasonic detection elements includes:
The ultrasonic receiving apparatus according to any one of claims 10 to 15, having both a Fabry-Perot resonator structure and a Bragg grating structure. 19. The ultrasonic receiving apparatus according to claim 10, further comprising: a broadband light source; and a narrow-band filter configured to narrow a band of light generated from the broadband light source. 20. The ASE (Amplified) wherein the broadband light source emits amplified spontaneous emission light.
20. The ultrasonic receiving apparatus according to claim 19, wherein the ultrasonic receiving apparatus is a Spontaneous Emission light source. 21. The band-narrowing filter has a Bragg grating structure made of the same material as the Bragg grating structure of the plurality of ultrasonic detection elements; 21. The ultrasonic receiving apparatus according to claim 20, wherein said ultrasonic detecting element is thermally coupled to the Bragg grating structure. 22. The method according to claim 10, wherein the light detector includes a CCD or a plurality of photodiodes.
Item 7. The ultrasonic receiving device according to Item 1. 23. The ultrasonic receiving apparatus according to claim 10, further comprising at least one of an acoustic matching layer, an acoustic lens, and a sound absorbing material. 24. A drive signal generation circuit for generating a drive signal for transmitting an ultrasonic wave, and an ultrasonic transmission for transmitting an ultrasonic wave toward a subject based on the drive signal output from the drive signal generation circuit An ultrasonic detection unit including a plurality of ultrasonic detection elements that modulate light based on an applied ultrasonic wave; and a light detection unit that detects light output from the ultrasonic detection unit and generates a detection signal. An ultrasonic diagnostic apparatus comprising: a detector; signal processing means for processing a detection signal output from the photodetector; and control means for controlling a transmission timing of the drive signal generation circuit and a reception timing of the signal processing means. apparatus. 25. An ultrasonic transmission unit comprising: an optical transmission line array including a plurality of optical transmission lines to which light is incident from a first end; and a second end of the plurality of optical transmission lines. 26. The ultrasonic diagnostic apparatus according to claim 24, further comprising: a plurality of ultrasonic detection elements that are configured to modulate light incident through the respective optical transmission paths based on ultrasonic waves reflected from the subject. 26. The ultrasonic detector according to claim 24, wherein the ultrasonic detector has a plurality of ultrasonic detecting elements arranged two-dimensionally, and modulates light based on ultrasonic waves reflected from the subject.
5. The ultrasonic diagnostic apparatus according to 5. 27. The ultrasonic diagnostic apparatus according to claim 24, further comprising an optical amplifier that amplifies light generated from a light source and enters the plurality of ultrasonic detecting elements. 28. The ultrasonic diagnostic apparatus according to claim 24, further comprising an optical amplifier that amplifies light output from the plurality of ultrasonic detection elements and makes the light incident on the photodetector. 29. Each of the plurality of ultrasonic detection elements,
ASE (Amplif) having a Bragg grating structure and emitting amplified spontaneous emission light
ied Spontaneous Emission)
A light source; and a narrow-band filter that has a Bragg grating structure made of the same material as the Bragg grating structure of the plurality of ultrasonic detection elements, and narrows a band of light generated from the ASE light source. The ultrasonic diagnostic apparatus according to any one of claims 24 to 28, wherein a Bragg grating structure of the narrow band filter and a Bragg grating structure of the plurality of ultrasonic detection elements are thermally coupled. . 30. The ultrasonic diagnostic apparatus according to claim 24, wherein the ultrasonic transmitting unit and the ultrasonic detecting unit are combined to form an ultrasonic transmitting / receiving unit.