JPH0458149

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DESCRIPTION JPH0458149
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
ultrasound probe, and more particularly to an ultrasound probe suitable for an ultrasound
microscope. [Prior Art] As is well known, an ultrasonic microscope is an apparatus which mainly
analyzes physical properties of the surface layer of an object using ultrasonic waves. In this
ultrasound microscope, an ultrasound probe is used to transmit and receive ultrasound. Such an
ultrasonic probe will be described with reference to FIG. FIG. 4 is a side view of a conventional
ultrasonic probe. In the figure, 1 shows an ultrasound probe. An acoustic lens 2 has a concave
lens surface 2a and a flat surface 2b opposed thereto. Reference numeral 3 denotes a conversion
element, which comprises a piezoelectric element 3a, a lower electrode 3b and an upper
electrode 3C. 3 d shows the lead wire connected to each electrode. The conversion element 3 is
fixed to the flat surface 2 b of the acoustic lens 2. 4 is an object to be inspected (object to be
inspected), and 5 is a medium (J water is usually used) interposed between the lens surface 2a
and the object 4 to be inspected. In the ultrasonic probe 1, when a predetermined voltage
(usually a burst wave) is applied to each of the electrodes 3b and 3C through the lead wire 3d,
the piezoelectric element 3a is excited to generate an ultrasonic wave. The ultrasonic waves pass
through the inside of the acoustic lens 2 as indicated by a broken line in the figure, and are
focused (line-focused) at the focal point F on the semi-cylindrical lens surface 2a. In the figure,
the case where the surface of the subject 4 and the focal point F coincide with each other is
shown. In this case, if the radiation angle θ of the ultrasonic wave from the lens surface 2a is
smaller than a predetermined critical angle determined by the inspection object 4, the ultrasonic
wave is reflected on the surface of the inspection object 4 and It returns and arrives at the
conversion element 3, and excites the piezoelectric element 3a. As a result, an electric signal
proportional to the size of the returned ultrasonic wave is output from the piezoelectric element
3a, and the state of the surface of the inspection object 4 is determined based on this electric
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signal. On the other hand, when the radiation angle θ of the ultrasonic wave from the lens
surface 2a is equal to or more than the critical angle, the ultrasonic wave incident on the
inspection object 4 at the critical angle propagates as a surface acoustic wave on the surface of
the inspection object 4, Of the surface acoustic waves, an ultrasonic wave emitted to a path
symmetrical to the radiation path reaches the conversion element 3. This ultrasonic wave is
incident on the inspection object 4 from near the central axis, is reflected on the surface, and
interferes with the ultrasonic wave returned from the radiation path, and this interference wave
excites the piezoelectric element 3a to output an electric signal. . The electrical signal of the
interference wave is collected while moving the ultrasonic probe 1 toward the test object 4 (in
the -Z direction) from the state of FIG. You can get the curve that you have.
This curve is the so-called V (Z) curve, which is shown in FIG. FIG. 5 is a waveform diagram
showing a V (Z) curve, in which the abscissa represents the position of the probe 1 and the
ordinate represents the received signal level of the interference wave. As shown, the V (Z) curve
has a constant period ΔZ. The period ΔZ has a predetermined relationship with the propagation
velocity of the surface acoustic wave of the test object 4, and the propagation velocity can be
understood by measuring the period ΔZ, and the physical properties of the inspection object can
be evaluated by knowing the propagation velocity. Can. SUMMARY OF THE INVENTION The
above-mentioned ultrasonic microscope is used for various objects to be inspected, but when the
type of object to be inspected is different, the surface acoustic wave velocity is also different, and
along with this, the critical angle It is usually different. In general, when measuring the surface
acoustic wave velocity from the V (Z) curve, it is necessary to consider the aperture angle of the
lens in accordance with the surface acoustic wave velocity of the sample in order to improve the
measurement accuracy. For example, if the surface acoustic wave velocity range is 5000 m / s or
more, an aperture angle (angle twice the maximum radiation angle) 60 'at 2000-6000 m / s and
a lens of 140 @ at 120' at 5000-5000 m / s It is considered good. Therefore, in the case of an
ultrasound microscope, it is necessary to change the probe 1 to an appropriate opening angle for
each object to be inspected. Furthermore, when the object to be inspected is a thin film, a
plurality of surface acoustic waves may be generated, and in this case, the probe 1 having an
opening angle passed for each surface acoustic wave must be replaced and used. . The
replacement of these ultrasound probes is not only extremely troublesome for the user, but it is
also necessary to stock many ultrasound probes, they have to be stored, and extra time in terms
of storage management. I needed it. An object of the present invention is to solve the problems in
the above-mentioned prior art and to provide an ultrasonic probe which can arbitrarily change
the opening angle. [Means for Solving the Problems] In order to achieve the above object,
according to the present invention, there is provided an acoustic lens having a lens concave
surface formed at one end, and an acoustic lens fixed on the acoustic lens at a position facing the
lens concave surface. An ultrasonic probe provided with a conversion element for generating an
ultrasonic wave upon application of a voltage and converting the received ultrasonic wave into
an electric signal proportional to the ultrasonic wave, the ultrasonic probe being disposed close
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to the lower part of the concave surface of the lens, It is characterized in that two shields facing
each other and shield drive means for simultaneously moving the two shields toward or away
from each other by the same distance at the same time or in the opposite direction are provided.
[Operation] When the shield driving means is operated, the two shields simultaneously move in
the same direction at the lower part of the concave surface of the lens. When the shields are
brought closer, the opening angle becomes smaller, and when the shields are separated, the
opening angle becomes larger. Thereby, it is possible to arbitrarily change the opening angle, and
it is possible to cope with various test objects or thin film test objects with one ultrasonic probe.
The present invention will be described below based on the illustrated embodiments. FIG. 1 is a
side view of an ultrasonic probe according to an embodiment of the present invention, and FIG. 2
is a perspective view of a shielding plate shown in FIG. The same reference numerals as in FIG. 4
denote the same parts in FIG. 1 and a description thereof will be omitted. Reference numerals
10a and 10b denote shielding plates extending in the same direction at the lower part of the lens
concave surface 2a, and lla and llb are arms supporting the shielding plates 10a and 10b at the
lower part and having a twisting hole at the upper part. Reference numerals 12a and 12b denote
supports fixed on opposite side surfaces of the acoustic lens 2, and project toward the front in
the figure. The reference numeral 13 denotes a butterfly rod which is screwed into the arms 11a
and 11b and the supports 12a and 12b. The shielding plates 10a and 10b are supported by the
supports 12a and 12b via the wing 13 and the arms 11a and 11b. Reference numeral 14 denotes
a knob for rotating the butterfly rod 13. The screws of the hinge bar 13 are cut oppositely at the
center left and right, and the screw holes of the arms 11a and 11b and the supports 12a and 12b
are also formed in the corresponding screw holes. Reference numeral 15 denotes the ultrasonic
probe of this embodiment. Next, the operation of this embodiment will be described with
reference to FIG. FIG. 3 is a side view of the vicinity of the concave surface 2a of the lens. In the
figure, the same parts as those shown in FIG. 1 are given the same reference numerals. When the
knob 14 is rotated, the butterfly rod 13 is also rotated, and the arms 11a and 11b move
according to this rotation. For example, when the knob 14 is rotated to the right, the arm 11a
moves to the left and the arm 11b moves to the right. As a result, the distance t (FIG. 3) between
the shielding plates 10a and 10b is expanded, and the opening angle θ is increased. Conversely,
when the knob 14 is turned to the left, the arm 11a moves to the right, and the arm 11b moves
to the left. As a result, the space t (FIG. 3) between the shielding plates 10a and 10b is
sandwiched, and the opening angle θ becomes smaller. Now, when the inspection object is
replaced from one inspection object to another, if the critical angle suitable for the inspection
object is smaller than the critical angle obtained at the opening angle used in the inspection
object, the inspector The knob 14 is rotated to the left, the shielding plates 10a and 10b are
moved closer to each other, and the gap is narrowed to change the setting of the opening angle
.theta.
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Conversely, when a larger critical angle is required, the knob 14 is rotated in the reverse
direction to increase the gap して to change the opening angle θ to an angle that can obtain an
appropriate critical angle. As described above, in the present embodiment, since the shielding
plate is selectively moved to the left and right, the opening angle can be arbitrarily changed, and
it is necessary to replace the ultrasonic probe every time the inspection object is replaced. There
is no, it will be easier to handle. In addition, it is possible to eliminate the need for having a large
number of ultrasonic probes, thereby saving the storage management time and reducing the cost
for the ultrasonic probes. It is apparent that the present invention is also applicable to a lens (line
focus lens) in which a lens concave surface is formed in a semi-cylindrical surface as an acoustic
lens. As described above, according to the present invention, since two shields simultaneously
moving in opposite directions are provided under the concave surface of the acoustic lens, the
opening angle of the concave surface of the lens can be arbitrarily selected. As a result, it is
possible to eliminate the need for replacing the ultrasound probe each time the subject is
replaced, and to facilitate the handling. In addition, it is possible to eliminate the need for having
a large number of ultrasonic probes, thereby saving the storage management time and reducing
the cost for the ultrasonic probes.
[0002]
Brief description of the drawings
[0003]
1 is a side view of an ultrasonic probe according to an embodiment of the present invention, FIG.
2 is a perspective view of a shielding plate shown in FIG. 1, FIG. 3 is a side view of a lens concave
surface, and FIG. 5 is a waveform diagram of the V (Z) curve.
2 ············· Acoustic lens, 3 ················································································································ Arm , 12a, 12b
... self ... support, 13 ...... insert pin, 4 ...... knob, probe 3 5 ...... ultrasonic inspection Figure 1 the 2
Fig. 4 Fig. 5 d
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