Ultrasound probe

An optical fiber guides light output from a light source to an ultrasound probe. The ultrasound probe includes a light guiding section that guides the light from a light input end, which is optically coupled with the optical fiber to a light output end provided in the vicinity of ultrasonic transducers. The light guiding section has a first light guiding portion that includes the light input end, and a second light guiding portion that includes the light output end. The first light guiding portion is formed by glass, and magnifies input light. The second light guiding portion is formed by resin, and emits the light toward a subject from the light output end.

TECHNICAL FIELD

The present invention is related to an ultrasound probe. More specifically, the present invention is related to an ultrasound probe which is employed in photoacoustic imaging.

The ultrasound examination method is known as an image examination method that enables examination of the state of the interior of living organisms in a non invasive manner. Ultrasound examination employs an ultrasound probe capable of transmitting and receiving ultrasonic waves. When the ultrasonic waves are transmitted to a subject (living organism) from the ultrasound probe, the ultrasonic waves propagate through the interior of the living organisms, and are reflected at interfaces among tissue systems. The ultrasound probe receives the reflected ultrasonic waves and images the state of the interior of the subject, by calculating distances based on the amounts of time that the reflected ultrasonic waves return to the ultrasound probe.

Photoacoustic imaging, which images the interiors of living organisms utilizing the photoacoustic effect, is also known. Generally, in photoacoustic imaging, pulsed laser beams such as laser pulses are irradiated into living organisms. Biological tissue that absorbs the energy of the pulsed laser beams generates ultrasonic waves (photoacoustic signals) by volume expansion thereof due to heat. An ultrasound probe or the like detects the photoacoustic signals, and constructs photoacoustic images based on the detected signals, to enable to enable visualization of the living organisms based on the photoacoustic signals.

In photoacoustic imaging, there are cases in which a pulsed laser beam is guided from a laser light source to an ultrasound probe, and the pulsed laser beam is emitted from a light emitting section provided on the ultrasound probe. An ultrasound probe equipped with a light emitting section is disclosed in Japanese Unexamined Patent Publication No. 2010-012295, for example. In the invention of Japanese Unexamined Patent Publication No. 2010-012295, a plurality of optical fibers are employed to guide light from a laser light source to an ultrasound probe. The output ends of the optical fibers constitute the light emitting section that emits light onto a subject. In the invention of Japanese Unexamined Patent Publication No. 2010-012295, a plurality of ultrasonic transducers that transmit and/or detect ultrasonic waves are arranged in a single dimension with predetermined intervals among the transducers. The output ends of the fibers, which are light emitting portions, are arranged in the gaps among adjacent ultrasonic transducers.

DISCLOSURE OF THE INVENTION

In the invention of Japanese Unexamined Patent Publication No. 2010-012295, the output ends of the optical fibers emit light toward the subject. Light is concentrated at the output ends of the optical fibers, which are thin, and the energy density of light at the output ends becomes high. In the invention of Japanese Unexamined Patent Publication No. 2010-012295, it is necessary to reduce the emitted amount of light, in order to emit light at an energy density that satisfies safety standards with respect to living organisms (20 mJ/cm2for light having a wavelength of 500 nm, for example). Because the amount of light emitted by each optical fiber is limited in this manner, it becomes necessary to increase the number of optical fibers in order to emit a sufficient amount of light while satisfying the safety standards. In addition, the optical fibers are arranged with predetermined intervals therebetween in the invention of Japanese Unexamined Patent Publication No. 2010-012295, and fluctuations arise in the amounts of light emitted at portions directly under optical fibers and portions under the spaces among adjacent optical fibers. Therefore, light cannot be uniformly emitted onto an area to be illuminated.

The present invention has been developed in view of the foregoing circumstances. It is an object of the present invention to provide an ultrasound probe having an illumination system capable of emitting a sufficient amount of light onto a wide illumination area.

To achieve the above objective, the present invention provides an ultrasound probe, comprising:

a plurality of ultrasonic transducers which are arranged along a predetermined direction;

an optical fiber that guides light emitted from a light source to a probe main body; and

light guiding means that guides light from a light input end which is optically coupled with the optical fiber to a light output end provided in the vicinity of the ultrasonic transducers;

the light guiding means including:

a first light guiding portion formed by a glass material that includes the light input end and guides light from the light input end toward the light output end and that enlarges the cross sectional area of input light at the light input end at an output end of the first light guiding portion; and

a second light guiding portion formed by a resin material that includes the light output end, guides light guided by the first light guiding portion to the light output end, and emits light from the light output end toward a subject.

The present invention may adopt a configuration, wherein:

the first light guiding portion includes a light guiding path formed in a tapered shape.

The present invention may adopt a configuration, wherein:

the first light guiding portion enlarges the width of guided light in the predetermined direction at an output end of the first light guiding portion to be at least greater than the width of the input light in the predetermined direction at the light input end.

The present invention may adopt a configuration, wherein:

the second light guiding portion is curved in a direction toward the interiors of the ultrasonic transducers.

Alternatively, the present invention may adopt a configuration, wherein:

the light guiding means is provided inclined at a predetermined angle with respect to ultrasonic wave detecting surfaces of the ultrasonic transducers.

The ultrasound probe may be provided with a plurality of the optical fibers and a plurality of the light guiding means. In this case, a configuration may be adopted, wherein the plurality of the light guiding means are arranged along the predetermined direction. The plurality of light guiding means may be arranged along a direction perpendicular to the predetermined direction instead of or in addition to being arranged in the predetermined direction so as to face the ultrasonic transducers which are interposed among the plurality of light guiding means.

Alternatively, the plurality of optical fibers which are arranged along the predetermined direction may be optically coupled to the light input end of a single light guiding means. In this case, two of the light guiding means may be provided; and the two light guiding means may be provided to face each other with the ultrasonic transducers interposed therebetween.

The light guiding means may be a slab shaped light guiding plate having a tabular core and planar cladding layers provided on both surfaces of the tabular core. Alternatively, the light guiding means may comprise a light transmitting portion having light transmitting properties and reflective members which are formed to sandwich the light transmitting portion therebetween.

In the ultrasound probe of the present invention, it is preferable for the distance from the light input end to the boundary between the first light guiding portion and the second light guiding portion to be 8 mm or greater.

The ultrasound probe of the present invention may further comprise:

an adapter that transmits light and ultrasonic waves, which is mounted to the ultrasound probe so as to cover the ultrasonic wave detecting surfaces of the ultrasonic transducers and the light output end of the light guiding means.

A configuration may be adopted, wherein the ultrasound probe of the present invention further comprises:

a diffusion plate that diffuses light at the light output side of the light output end.

Alternatively, a configuration may be adopted, wherein:

a diffusing surface that diffuses light is formed on at least one of the end surface at the light output side of the second light guiding portion and the end surface of the second light guiding portion at the boundary between the first light guiding portion and the second light guiding portion.

The ultrasound probe of the present invention couples the light guiding means to the output ends of the optical fibers that guide light to a probe main body, employs the light guiding means to guide the light to the vicinity of the ultrasonic transducers, and emits light to a subject from the vicinity of the ultrasonic transducers. The light guiding means includes the first light guiding portion and the second light guiding portion. The first light guiding portion enlarges the cross sectional area of light to be greater than that at the light input end. Thereby, light emission onto a greater area compared to a case in which light is emitted from the output ends of optical fibers is enabled, from the light output end having a larger area than the output ends of optical fibers. In addition, the energy density of light at the light output end can be decreased compared to the energy density of light at the light input end. For these reasons, the amount of light which is input into optical fibers can be increased compared to a case in which light is emitted onto a subject from the output ends of optical fibers, and light emission with a sufficient amount of light while satisfying safety standards becomes possible.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.FIG. 1illustrates a photoacoustic image diagnosis apparatus that includes an ultrasound probe according to a first embodiment of the present invention. The photoacoustic image diagnosis apparatus includes: an ultrasound probe10; a light source unit31; and an ultrasonic wave unit32. The ultrasound probe10includes: a light emitting section that emits light onto subjects; and ultrasonic transducers which are capable at least of detecting ultrasonic waves from subjects. The light source unit31is a laser unit that generates pulsed laser beams, for example, and generates light to be emitted onto subjects by the ultrasound probe10. The ultrasonic wave unit32generates photoacoustic images based on ultrasonic wave signals detected by the ultrasound probe10.

The ultrasound probe10includes: an array portion, in which a plurality of ultrasonic transducers are arranged in a predetermined direction; and a grip portion which is held by an operator when utilizing the probe, for example. The arrangement of the ultrasonic transducers may be one dimensional or two dimensional. The ultrasound probe10is connected to the light source unit31via optical fibers21. The optical fibers21include a plurality of optical fibers, for example. The pulsed laser beam generated by the light source unit is guided to the ultrasound probe10by the optical fibers21, and emitted onto a subject from the light emitting section of the ultrasound probe10. In addition, the ultrasound probe10is connected to the ultrasonic wave unit32via an electrical cable22.

FIG. 2Ais a sectional view of the ultrasound probe10in the lateral direction, andFIG. 2Bis a sectional view of the ultrasound probe10in the frontal direction. Note that the electrical cable22is omitted inFIG. 2AandFIG. 2B. As illustrated inFIG. 2A, the ultrasound probe10has ultrasonic transducers12on the surface thereof toward the side that contacts a subject. Light guiding plates (light guiding means)11aand11dthat form light guiding paths or wave guiding paths are provided at both sides of the ultrasonic transducers12. Alight input end of the light guiding plate11ais optically coupled with an optical fiber21a, and a light input end of the light guiding plate11dis optically coupled with an optical fiber21d. Quartz fibers or hollow fibers may be employed as the optical fibers21aand21d. Bundled fibers, in which a plurality of optical fibers are bundled, may also be employed as the optical fibers21aand21d.

The surfaces of the light guiding plates11aand11dopposite the light input ends thereof constitute light output ends. The light output ends are provided in the vicinity of the ultrasonic transducers. The light guiding plates11aand11dguide light input into the light input ends thereof to the light output ends thereof. The light guiding plates11aand11dare slab shaped light guiding plates having tabular cores and planar cladding layers provided on both surfaces of the tabular cores. The refractive indices of the cores and the cladding layers are different. Therefore, total reflection occurs at the boundaries between the cores and the cladding layers, and light propagates therethrough with substantially no loss. Alternatively, reflective films may be coated on the tabular cores, to guide light waves, or light waves may be guided by total reflection caused due to differences in refractive indices between the cores and air. Light diffusing plates13are provided at the light output ends of the light guiding plates11aand11d. The light output surfaces of the light diffusing plates13constitute the light emitting section of the ultrasound probe10.

The light guiding plates11aand11dface each other in a direction perpendicular to the direction in which the ultrasonic transducers12are arranged, with the ultrasonic transducers interposed therebetween. As illustrated inFIG. 2B, three light guiding plates11athrough11cthat include the light guiding plate11aare provided on the side of the ultrasonic transducers12at which the light guiding plate11ais provided. The light guiding plates11athrough11care arranged along the direction in which the ultrasonic transducers12are arranged. An optical fiber21bis optically coupled with the light guiding plate11b, and an optical fiber21cis optically coupled with the light guiding plate11c. Although not illustrated inFIG. 2B, three light guiding plates that include the light guiding plate11dare provided on the ultrasonic transducers12at which the light guiding plate11dis provided. These three light guiding plates are also arranged along the direction in which the ultrasonic transducers12are arranged, and are optically coupled to corresponding optical fibers.

FIG. 3is a diagram that illustrates a light guiding plate11. InFIG. 3, the light guiding plate11is illustrated as viewed from the lateral direction (the same direction asFIG. 2A). The light guiding plate11has: a first light guiding portion41that includes a light input end51; and a second light guiding portion42that includes a light output end52. The first light guiding portion41guides light input into the light input end51toward the light output end52. The second light guiding portion42guides the light guided thereto by the first light guiding portion41to the light output end52.

The first light guiding portion41is formed by a glass material. The first light guiding portion41includes alight guiding path which is formed as a tapered shape, for example. The first light guiding portion41enlarges the cross sectional area of light at a light output end of the first light guiding portion41compared to the cross sectional area of light input at the light input end51. For example, the first light guiding portion41enlarges the width of guided light in the direction in which the ultrasonic transducers are arranged at the output end of the first light guiding portion41to be at least greater than the width of the input light in the direction in which the ultrasonic transducers are arranged at the light input end51. Meanwhile, the second light guiding portion42is formed by a resin material, such as acryl. The second light guiding portion42emits light toward a subject from the light output end52.

Light output by the light source unit31(FIG. 1) propagates through the optical fibers21and is guided to the ultrasound probe10. The optical fibers21include a plurality of optical fibers, and each optical fiber is optically coupled with the light input end51(FIG. 3) of a light guiding plate11corresponding thereto. The light that enters the light guiding plates11through the light input ends51propagates through the first light guiding portions41, which are formed into tapered shapes, while enlarging the range of light. The light which has passed through the first light guiding portions41enter the second light guiding portions42, and is guided to the light output ends52. The guided light is emitted onto the subject from the light output end52via the light diffusing plates13(FIG. 2AandFIG. 2B).

In the present embodiment, the light guiding plates11are coupled to the output ends of the optical fibers that guide light to the probe main body, the light guiding plates11are employed to guide light to the vicinity of the ultrasonic transducers, and light is emitted onto the subject from the vicinity of the ultrasonic transducers, instead of emitting light directly toward the subject from the output ends of the optical fibers. The light guiding plates11include the first light guiding portions41and the second light guiding portions42. The first light guiding portions41enlarge the cross sectional area of light to be greater than that at the light input ends51. Therefore, light can be emitted from a greater area compared to a case in which light is emitted from the output ends of optical fibers. In addition, the energy density of light at the output side can be reduced compared to the energy density of light at the light input ends51for the amount of increase in the light emission area. For this reason, the amount of light caused to enter the optical fibers can be increased compared to a case in which light is emitted onto a subject from the output ends of optical fibers, and a sufficient amount of light can be emitted while satisfying safety standards.

In the present embodiment, the light guiding plates11increase the width of light in the direction in which the ultrasonic transducers12are arranged. If light is emitted from optical fibers without employing the light guiding plates11, the light will be emitted discretely in the direction in which the ultrasonic transducers are arranged. Therefore, portions directly under the optical fibers will be illuminated with large amounts of light, while portions among adjacent optical fibers will be illuminated with smaller amounts of light. Because the present embodiment increases the width of light in the direction in which the ultrasonic transducers12are arranged, light can be emitted over a wide range in the direction in which the ultrasonic transducers12are arranged from a single optical fiber. For this reason, fluctuations in the amounts of light emitted in the direction that the ultrasonic transducers12are arranged are resolved compared to cases in which optical fibers directly emit light. Therefore, light can be uniformly emitted onto a wide area to be illuminated.

Here, in order to increase the amount of light which is output from the light output ends52, it is necessary to cause a greater amount of light to enter the optical fibers, and the energy density increases at the light output ends of the optical fibers and at the light input ends51. If the energy density at these locations becomes great, there is a possibility that the light input ends51will be damaged. Therefore, the first light guiding portions41that include the light input ends51are formed by a glass material in the present embodiment. Damage to the light input ends51(the first light guiding portions41) can be prevented even when light enters the light input ends51at a high energy density, by employing glass as the material thereof. Meanwhile, the second light guiding portions42are formed by a resin material in the present embodiment. Resin materials are advantageous in that they are easily processed.

FIG. 4AandFIG. 4Billustrate an example of a modified light guiding plate11. InFIG. 4A, the light guiding plate11is illustrated as viewed from the lateral direction (the same direction asFIG. 2A). InFIG. 4B, the light guiding plate11is illustrated as viewed from the frontal direction (the same direction asFIG. 2B). As illustrated inFIG. 4A, the second light guiding portion42is curved in this example. In addition, as illustrated inFIG. 4B, the second light guiding portion42enlarges light in the direction that the ultrasonic transducers are arranged toward the light output end52. In this case, an advantageous effect that uniformity of light at the light output ends52is improved can be expected, compared to a case in which the second light guiding portion42is formed in a linear shape (a rectangular plate) as illustrated inFIG. 2B. The first light guiding portion41that includes the light input end51is the same as that illustrated in FIG.3.

The second light guiding portion42of the light guiding plate11illustrated inFIG. 4AandFIG. 4Bis curved toward the interior of the ultrasonic transducers within a range that satisfies conditions for total reflection, for example. When light is emitted toward a subject from the sides of the ultrasonic transducers as illustrated inFIG. 2B, there are cases in which it is difficult for light to reach the portion directly under the ultrasonic transducers12. Employing the light guiding plates11which are curved toward the interior of the ultrasonic transducers as illustrated inFIG. 4Ato output light in oblique directions from the light output ends52facilitates light emission to the portion directly under the ultrasonic transducers12from the light guiding plates provided at the sides of the ultrasonic transducers12. Such three dimensional processing is easy because the second light guiding portions42are formed by a resin material.

Note that inFIG. 2AandFIG. 2B, a plurality of combinations of optical fibers and light guiding plates are provided. However, it is not necessary for a plurality of optical fibers and a plurality of light guiding plates to be provided. For example, a configuration may be adopted, wherein a single optical fiber guides light from the light source unit31(FIG. 1) to the ultrasound probe10, and a single light guiding plate11provided within the ultrasound probe10spreads the width of the light within a range in which the ultrasonic transducers12are arranged. In addition, it is not necessary for the plurality of light guiding plates to be provided at both sides of the ultrasonic transducers12. For example, a configuration may be adopted, wherein a plurality of light guiding plates provided along the arrangement direction of the ultrasonic transducers12at a single side of the ultrasonic transducers emit light from the single side of the ultrasonic transducers12.

Next, a second embodiment of the present invention will be described.FIG. 5illustrates a light guiding plate60which is employed in an ultrasound probe according to the second embodiment of the present invention. The light guiding plate60of the present embodiment has a first light guiding portion61formed by glass and a second light guiding portion62formed by resin, in the same manner as the light guiding plate11of the first embodiment. In the first embodiment, the three optical fibers21athrough21cand the three light guiding plates11athrough11cwere coupled to each other, respectively (FIG. 2B). In the present embodiment, a plurality of optical fibers21are optically coupled to the light input end of a single light guiding plate60.

InFIG. 5, the longitudinal direction of the light guiding plate60inFIG. 5corresponds to the direction in which the ultrasonic transducers12(FIG. 2AandFIG. 2B) are arranged. Four optical fibers21are arranged at equidistant intervals along the arrangement direction of the ultrasonic transducers, for example. The four optical fibers21are optically coupled to the light input end of the light guiding plate. The ultrasound probe may be equipped with two light guiding plates60, which are provided to face each other with the ultrasonic transducers interposed therebetween.

The light guiding plate60(the first light guiding portion61and the second light guiding portion62) is formed to be of a parallelepiped shape, for example. The length of the first light guiding portion61in the direction in which light is guided is designated as A, and the length of the second light guiding portion62in the direction in which light is guided is designated as B. The first light guiding portion61guides light that enters thereinto from the side of the light input end to the second light guiding portion62, while enlarging the cross sectional area of the light. For example, if the length of the first light guiding portion61is 11 mm, the fiber core diameters of the optical fibers21are 0.3 mm, and the fiber light output has a NA (Numerical Aperture) equivalent to 0.22, the first light guiding portion61enlarges the cross sectional area of the light from φ0.3 mm=7·10−4cm2to φ2.8 mm=0.062 cm2. The second light guiding portion62guides the light guided thereto by the first light guiding portion61to the light output end thereof in the vicinity of the ultrasonic transducers.

FIG. 6is an image that illustrates the distribution of light at a boundary surface between the first light guiding portion61and the second light guiding portion62. A light guiding plate60having a cross section with a width of 40 mm and a height of 3 mm will be considered. It is assumed that the fiber core diameters of the optical fibers21are 0.3 mm, and the fiber light output has a NA (Numerical Aperture) equivalent to 0.22. In addition, it is assumed that the refractive index of the first light guiding portion61is 1.45.FIG. 6is an image that illustrates the distribution of light in the case that the length A of the first light guiding portion61is 12 mm. In other words,FIG. 6illustrates the distribution of light at a cross section 12 mm remote from the light input end of the light guiding plate60. The black portions in the image correspond to portions where the light is weak, and the white portions correspond to portions where the light is strong.

FIG. 7is a graph that illustrates the relationship between the distance from the light input and the energy density of light. The horizontal axis of the graph represents the distance from the light input end to the boundary surface between the first light guiding portion61and the second light guiding portion62, that is, the length of the first light guiding portion61. The vertical axis represents the maximum value of the energy density of light (for example, the energy density at a portion in which the average energy density is highest within a 1 mm·1 mm region) at the boundary surface between the first light guiding portion61and the second light guiding portion62. Cases were considered in which the energy input to the optical fiber is 12.5 mJ and 10 mJ. Referring toFIG. 7, it can be understood that the maximum values of the energy density of light become greater as the length of the first light guiding portion61becomes shorter. This is because the cross sectional area of light is smaller as the length of the first light guiding portion61is shorter.

Here, if the energy density of light that enters the second light guiding portion62is excessively high, there is a possibility that the resin, polycarbonate for example, that constitutes the second light guiding portion62will be damaged. It is known that resin will be damaged if light having an energy density of 180 mJ/cm2or greater enters thereinto, based on the heat resistance standards (temperature, etc.) of polycarbonate and experimental results. Referring toFIG. 7, cases in which the energy density at the boundary surface between the first light guiding portion61and the second light guiding portion62exceeds 180 mJ/cm2(threshold level) occur when the length of the first light guiding portion61is less than 11 mm in the case that the energy input into the optical fibers is 12.5 mJ, and when the length of the first light guiding portion61is less than 8 mm in the case that the energy input into the optical fibers is 10 mJ. It is desirable for the length of the first light guiding portion61to be 8 mm or greater, because energy which is practically capable of being input to the optical fibers is approximately 10 mJ. With respect to the length of the second light guiding portion62, this length is not particularly limited, and may be selected as appropriate according to targets of measurement, etc.

A plurality of optical fibers are coupled to a single light guiding plate60in the present embodiment. Even in such a case, the same advantageous effects as those obtained by the first embodiment are obtained, because the light guiding plate60includes the first light guiding portion61formed by glass and the second light guiding portion62formed by resin. In addition, the energy density of light that enters the second light guiding portion62can be made lower than the threshold level by setting ht length of the first light guiding portion61to be 8 mm or greater, thereby preventing damage to the second light guiding portion62.

Next, a third embodiment of the present invention will be described.FIG. 8is a sectional diagram of an ultrasound probe10according to the third embodiment of the present invention in the lateral direction. The ultrasound probe10is equipped with two light guiding plates70that face each other with the ultrasonic transducers12interposed therebetween. The light guiding plates70have first light guiding portions71formed by glass and second light guiding portions72formed by resin. The first light guiding portions correspond to the first light guiding portion41illustrated inFIG. 3or the first light guiding portion61illustrated inFIG. 5. The second light guiding portions72correspond to the second light guiding portion42illustrated inFIG. 3or the second light guiding portion62illustrated inFIG. 5. The second light guiding portions72are curved toward the ultrasonic transducers.

In the present embodiment, the ultrasound probe10is further equipped with an adapter14, which is a resin gel adapter or the like. The adapter14has light transmitting properties and ultrasonic wave transmitting properties. The adapter14is mounted onto the ultrasound probe10so as to cover ultrasonic wave detecting surfaces of the ultrasonic transducers12and the light output surfaces of the light guiding plates70. Light guided by the light guiding plates70is emitted onto a subject via the adapter14. Light emission onto regions directly under the ultrasonic transducers, which are difficult to emit light onto, is facilitated by use of the adapter14. The ultrasound probe of the third embodiment is the same as those of the first and second embodiments in the remaining points.

Next, a fourth embodiment of the present invention will be described.FIG. 9is a sectional diagram of an ultrasound probe10according to the fourth embodiment of the present invention in the lateral direction. The ultrasound probe10is equipped with two light guiding plates80that face each other with the ultrasonic transducers12interposed therebetween. The light guiding plates80have first light guiding portions81formed by glass and second light guiding portions82formed by resin. The first light guiding portions correspond to the first light guiding portion41illustrated inFIG. 3or the first light guiding portion61illustrated inFIG. 5. The second light guiding portions82correspond to the second light guiding portion42illustrated inFIG. 3or the second light guiding portion62illustrated inFIG. 5.

Light diffusing surfaces are formed at the end surfaces of the second light guiding portions82toward the light output sides thereof. For example, protrusions and recesses that diffuse light are formed on the end surfaces of the second light guiding portions82toward the light output sides thereof. Light diffusing surfaces may be formed at the end surfaces of the second light guiding portions82toward the light input sides thereof (toward the boundaries thereof with the first light guiding portions81) instead of or in addition to the light diffusing surfaces on the end surfaces toward the light output sides thereof. The need to provide separate light diffusing plates13(FIG. 2AandFIG. 2B) is obviated, by imparting the second light guiding portions62with the function of diffusing light.

In addition, in the present embodiment, the light guiding plates80are provided at predetermined angles with respect to the ultrasonic wave detecting surfaces of the ultrasonic transducers12such that the light output from the light guiding plates80will propagate in directions toward the interiors of the ultrasonic transducers12, instead of forming the second light guiding portions to be curved toward the interiors of the ultrasonic transducers. By providing the light guiding plates80such that they are inclined in this manner, light can be emitted toward a direction directly under the ultrasonic transducers from the light output surfaces of the light guiding plates80.

Next, a fifth embodiment of the present invention will be described.FIG. 10is a sectional diagram of an ultrasound probe10according to the fifth embodiment of the present invention in the lateral direction. The ultrasound probe10is equipped with two light guiding plates90that face each other with the ultrasonic transducers12interposed therebetween. The light guiding plates90have first light guiding portions91formed by glass and second light guiding portions92formed by resin. The first light guiding portions91correspond to the first light guiding portion41illustrated inFIG. 3or the first light guiding portion61illustrated inFIG. 5. The second light guiding portions92correspond to the second light guiding portion42illustrated inFIG. 3or the second light guiding portion62illustrated inFIG. 5. Light diffusing surfaces may be formed on at least one of the end surfaces of the second light guiding portions92toward the light input sides and the light output sides thereof.

Each of the light guiding plates90includes a light transmitting portion that has light transmitting properties and reflecting members which are formed to sandwich the light transmitting portion therebetween. InFIG. 10, the first light guiding portions91correspond to the light transmitting portions, and reflective films93correspond to the reflecting members. Inorganic materials, aluminum, etc. may be employed as the material of the reflective films93. The reflective films93are provided on the first light guiding portions91inFIG. 10. An alternate configuration, in which the reflective films93are provided on the second light guiding portions92, may be adopted. Another alternate configuration, in which a material having a lower refractive index than that of the core light transmitting portions is provided to sandwich the core instead of sandwiching the core with the reflective members, may also be adopted. An organic material such as CYTOP may be employed as the material having the lower refractive index. Even if these configurations are adopted, light that enters the light guiding plates from the optical fiber can be prevented from leaking out from the lateral surfaces of the light guiding plates.

The present invention has been described above based on preferred embodiments. However, the ultrasound probe of the present invention is not limited to the above embodiments. Various changes and modifications to the above embodiments are included within the scope of the present invention.