JPH10213429A - Beam-diameter measuring target for ultrasonic-point focusing submerged contact and method and device for measuring beam diameter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the ultrasonic-beam diameter of a high frequency accurately. SOLUTION: A beam-diameter measuring device 1 for an ultrasonic-point focusing submerged contact performs the beam-diameter measurement of an ultrasonic wave under the state, wherein a plate-shaped target 3 and a contact 4 are submerged in a water tank 2. The plate-shaped target 3 is made of a thin plate-shaped metal piece, bonded to a side surface 5a of a holder 5 under the appropriately vertical state and supported as the bottom part of the water tank 2. The contact 4 transmits the ultrasonic wave from a transmitting/receiving plane 4a to the plate-shaped target 3 during the movement into the X direction. The ultrasonic wave, which is reflected from an upper edge 3a of the plate-shaped target 3, is received with the transmitting/ receiving plane 4a of the contact 4. Since the intensity distribution of the ultrasonic wave is obtained from the receiving level of the receiving signal in this way, the intensity distribution of the ultrasonic wave of a high frequency can be accurately measured by receiving the reflected wave. Then, the directivity of the contact 4 can be judged based on the intensity distribution, and the beam diameter of the ultrasonic wave can be measured at the same time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beam diameter measuring method for an ultrasonic point-focusing water immersion probe configured to accurately measure a beam diameter of a high-frequency ultrasonic wave transmitted from a probe underwater. TECHNICAL FIELD The present invention relates to a target for use, a beam diameter measuring method thereof, and a beam diameter measuring device thereof.

[0002]

2. Description of the Related Art An ultrasonic point-focused water immersion probe (hereinafter, simply referred to as a "probe") used for nondestructive inspection such as an ultrasonic inspection test for examining a welded portion using ultrasonic waves is known. The performance has been confirmed by measuring the directivity of ultrasonic waves propagating in water.

[0003] Since the ultrasonic wave transmitted from the probe travels straight, the intensity on the center line is the strongest, and the intensity becomes weaker as it shifts in the radial direction. Then, the beam diameter is measured from the intensity distribution of the ultrasonic wave, and the directivity of the ultrasonic wave transmitted from each probe is determined. Conventionally, a spherical target (reflector) is provided in water, and the ultrasonic wave transmitted from the probe is reflected by the spherical target and propagates through the water. The reflected ultrasonic wave (echo) is received and the ultrasonic wave is reflected. The intensity distribution is measured. The probe and the spherical target are opposed to each other at a predetermined distance in the water tank, and the ultrasonic wave is transmitted from the probe to the spherical target while moving the probe or the spherical target, and the ultrasonic wave reflected from the spherical target is reflected. Sound waves are received by the probe. Then, the intensity of the ultrasonic wave can be known from the reception level received by the probe.

[0004] Further, since the diameter of a spherical target varies depending on the frequency of the ultrasonic wave, the diameter of the spherical target must be in accordance with the beam diameter.
It is said that a double diameter is required. For example, when the ultrasonic wave has a high frequency of about 20 to 50 MHz, the beam diameter becomes several tens of microns (μm), so that a spherical target having a diameter of several hundred microns (μm) is used.

[0005]

However, in order to process a spherical target into a perfect circle, the diameter of the spherical target is limited to 0.3 mm, and it is difficult to accurately process a spherical target having a diameter of 0.3 mm or less. difficult. On the other hand, when performing a flaw detection test on a fine portion, the frequency of the ultrasonic wave must be higher. In this case, since the characteristics of the probe are measured using a spherical target having a diameter of 0.3 mm or less, the beam diameter of the high-frequency ultrasonic wave cannot be measured accurately, and the high-frequency The performance test of the probe transmitting the ultrasonic wave was not performed.

Therefore, when examining the intensity distribution of ultrasonic waves using a spherical target, even when a spherical target having a diameter of 0.3 mm is used, the intensity distribution of high-frequency ultrasonic waves having a wavelength λ of 0.1 mm or less is obtained. It is not possible to measure accurately, and the beam diameter decreases as the frequency increases, so that the measurement error increases. For example, when performing a flaw detection test on a fine pattern or the like of a finely processed semiconductor, an ultrasonic wave having a high frequency of about 50 MHz is transmitted. When testing a probe that transmits such high-frequency ultrasonic waves using a spherical target having a diameter of 0.3 mm, the ultrasonic waves reflected by the spherical target diffuse in the radial direction because the spherical target is too large. As a result, the intensity distribution of the ultrasonic wave could not be measured accurately.

Accordingly, an object of the present invention is to provide a beam diameter measuring target of an ultrasonic point focusing water immersion probe, a beam diameter measuring method thereof, and a beam diameter measuring apparatus which solve the above problems.

[0008]

In order to solve the above problems, the present invention has the following features. Claim 1
The invention is directed to a beam diameter measuring target of an ultrasonic point focusing water immersion probe having a reflecting surface for reflecting ultrasonic waves transmitted from a probe underwater, wherein the reflecting surface corresponds to the wavelength of the ultrasonic wave. And has a predetermined thickness, and is formed to extend longer than the beam diameter of the ultrasonic wave.

According to the first aspect of the present invention, the reflecting surface of the target has a predetermined thickness corresponding to the wavelength of the ultrasonic wave and is formed so as to extend longer than the beam diameter of the ultrasonic wave. In addition, it is possible to accurately measure the intensity distribution of high-frequency ultrasonic waves. In addition, by forming the target in a thin plate shape, the linear reflecting surface can be processed with high precision, so that a target corresponding to a high frequency wavelength can be manufactured.

According to a second aspect of the present invention, an ultrasonic beam transmitted from the probe is reflected on a target while moving either the probe or the target in water, and the beam diameter of the ultrasonic wave is measured. In the method of measuring the beam diameter of an ultrasonic point-focusing water immersion probe, the target is formed in a plate shape having a predetermined thickness corresponding to the wavelength of the ultrasonic wave, and substantially perpendicular to a narrow end face of the target. The ultrasonic wave is transmitted from a direction, the ultrasonic wave reflected by the end face of the target is received, and the beam diameter of the ultrasonic wave is measured.

Therefore, according to the second aspect of the present invention, the ultrasonic wave is transmitted from a direction substantially perpendicular to the narrow end face of the target, the ultrasonic wave reflected by the end face of the target is received, and the beam diameter of the ultrasonic wave is reduced. Since the measurement is performed, the intensity distribution of the high-frequency ultrasonic wave can be accurately measured.

According to a third aspect of the present invention, there is provided a beam diameter measuring apparatus for an ultrasonic point-focusing immersion probe for measuring an ultrasonic beam diameter by reflecting ultrasonic waves transmitted from a probe underwater. A plate-shaped target formed in a plate shape having a predetermined thickness corresponding to the wavelength of the ultrasonic wave, having a narrow reflecting surface extending linearly, and provided below the probe; And a holder for holding the plate-shaped target so that ultrasonic waves are propagated from a direction substantially perpendicular to the linearly formed reflecting surface of the target.

Therefore, according to the third aspect of the present invention, the plate-like target having a narrow reflecting surface formed in a straight line is held by the holder, and the ultrasonic wave is applied from a direction substantially perpendicular to the reflecting surface of the plate-like target. Is propagated, so that the reflection efficiency of the ultrasonic wave is enhanced, and the intensity distribution of the high-frequency ultrasonic wave can be accurately measured.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front view showing the configuration of an embodiment of a beam diameter measuring device for an ultrasonic point-focusing immersion probe according to the present invention, and FIG. It is a side view.

The beam diameter measuring apparatus 1 for an ultrasonic point-focusing water immersion probe includes a plate-like target 3 and a probe 4 in water in a water tank 2.
Then, the beam diameter of the ultrasonic wave is measured in a state of immersion. The plate-shaped target 3 is made of a thin plate-shaped metal piece, also called a “shim,” and is vertically adhered to the side surface 5 a of the holder 5 and held at a predetermined position on the bottom of the water tank 2.

The probe 4 has a built-in vibrator made of a piezoelectric element or the like, and is supported substantially vertically so that the lower end is the transmitting / receiving surface 4a of the vibrator. In addition, probe 4
Is height-adjusted such that the transmitting / receiving surface 4a is located a predetermined distance La above which the maximum echo can be obtained from the upper end surface 3a of the plate target 3. The plate-like target 3 includes a probe 4
The upper end face formed in a plate shape having a thickness t corresponding to the frequency of the ultrasonic wave transmitted from the optical disc and extending linearly functions as a reflecting surface for reflecting the ultrasonic wave.

The probe 4 is supported by an XY direction drive section 6 driven in the X direction or the Y direction by drive means such as a pulse motor (not shown), and is moved in the Z direction. And is supported by an elevating mechanism 7 for adjusting the distance in the Z direction from the plate-shaped target 3. The XY direction drive unit 6 is provided with a manual handle (not shown) that can be moved by a minute distance smaller than the distance driven by one pulse of the pulse motor. Note that the XY direction driving unit 6 may be configured to be driven by driving means other than the pulse motor.

FIG. 3 is a diagram showing an example for explaining the operation when measuring the directivity of the ultrasonic wave transmitted from the probe 4. After the distance La to the upper end surface 3a of the plate target 3 is adjusted to a predetermined distance by the lifting mechanism 7, the probe 4 moves from the transmitting / receiving surface 4a while moving in the X direction as shown by the arrow in FIG. A sound wave is transmitted toward the plate target 3. The ultrasonic wave reflected on the upper end surface 3a of the plate target 3 propagates in the water and is received on the transmitting / receiving surface 4a of the probe 4.

Then, transmission and reception of ultrasonic waves are repeated while moving the probe 4 in the X direction. Thus, the probe 4
When the ultrasonic wave reflected from the plate-shaped target 3 is received by the probe 4 while the relative position of the plate-shaped target 3 and the X-direction is gradually changed, the intensity distribution of the ultrasonic wave is obtained from the reception level of the received signal. I get it.

In this embodiment, the plate-like target 3 is held substantially vertically, and the probe 4 emits ultrasonic waves from above the plate-like target 3 toward the upper end surface 3a of the plate-like target 3. The configuration for transmission is described as an example. However, the present invention is not limited to this. For example, the plate-like target 3 is held in a horizontal state, and the probe 4 transmits ultrasonic waves from the horizontal direction of the plate-like target 3. It is also possible to adopt a different arrangement. In this case, the beam diameter of the ultrasonic wave can be measured by moving the probe 4 up and down.

That is, it is sufficient if the ultrasonic wave from the probe 4 is transmitted from a direction substantially perpendicular to the upper end surface 3a of the plate-like target 3, so that the probe 4 and the plate-like target The mounting direction of 3 can be set to any direction. FIG. 4 is a diagram illustrating an example of a state in which the plate target 3 is held on the side surface 5a of the holder 5.

The holder 5 is formed of a rectangular parallelepiped metal block (or a block having strength other than metal), and has a groove 5b penetrating in the X direction at the center of the upper surface thereof. The plate-shaped target 3 has a thickness t in the X direction corresponding to the wavelength of the ultrasonic wave, and has a length Lb in the Y direction extending longer than the beam diameter of the ultrasonic wave (Lb = the width of the groove 5b) or more. Have a length.

The linear upper end face 3a of the plate target 3 is mounted on the side face 5a of the holder 5 so as to face the transmitting / receiving face 4a of the probe 4. Then, the upper end surface 3a of the portion of the plate-like target 3 facing the groove 5a becomes a reflecting surface for reflecting the ultrasonic waves. As described above, the plate-like target 3 has the side surface 5 except for the portion facing the groove 5 b of the holder 5.
Since it is fixed in a state in which it is in contact with a, the effective length of the beam diameter measurement is the length Lb (= width of the groove 5b) facing the groove 5b.

Therefore, the probe 4 moves in the X direction with the center of the transmitting / receiving surface 4a between the grooves 5b of the holder 5. Thereby, the ultrasonic waves transmitted downward from the transmitting / receiving surface 4a are:
The light can be reflected on the upper end surface 3a of the plate-like target 3 having a predetermined thickness t. Further, the plate-shaped target 3 is easier to process than a spherical target, and can be manufactured with a high accuracy to a thickness of several microns such as a clearance gauge (thickness gauge). A plurality of types having different thickness dimensions are prepared in advance, and are exchanged according to the frequency characteristics of the probe 4.

Therefore, for example, 20 to 50
Even when transmitting high frequency ultrasonic waves of about MHz,
The reflected wave reflected by the upper end surface 3a of the plate-shaped target 3 having the thickness t corresponding to the frequency can be received, and the intensity distribution of the ultrasonic wave can be accurately measured. Then, the directivity of the probe 4 can be determined based on the intensity distribution, and the beam diameter of the ultrasonic wave can be measured.

FIG. 5 is a principle diagram for explaining a method of calculating a scan graph of the upper end face 3a of the plate-like target 3. In non-destructive inspections such as ultrasonic testing, the width in the X direction is W
(= Thickness t), and a band-like defect whose length in the Y direction is 2U (= Lb) is detected by an ultrasonic point-focusing water immersion probe.
The formula for calculating the scanning graph when flaw detection is performed in a direction perpendicular to a) is as follows.

The calculation of the height of the echo reflected from the plate-like target 3 uses the "theorem of the calculation of the echo height" shown in the following equation (1).

[0028]

(Equation 1)

Here, P _F is the reception sound pressure due to the defect echo, P _O is the transmission sound pressure immediately before the vibrator, R is the radius of the circular vibrator, ds is the minute area of the defect, and I is b from the vibrator. And the sound pressure P by the transmitting transducer at a distance of ξ from the central axis of the transducer on a band-shaped planar defect perpendicular to the sound axis.
/ Is a P _O.

For example, when the calculation is performed for the case where the probe 4 transmits an ultrasonic wave of 50 MHz, the following is obtained. FIG. 6 shows a calculation result of the echo height when the plate-shaped target 3 having a thickness t = 0.01 mm is used, and FIG. 7 shows an echo when the plate-shaped target 3 having a thickness t = 0.002 mm is used. The calculation result of height is shown.

In both figures, the broken line is a graph showing the directivity of the echo of the point reflection source, and the solid line is a graph showing the calculation result of the echo of the narrow plate-like target. From the graphs shown in both figures, it can be seen that the directivity of the echo of the point reflection source indicated by the broken line substantially matches the calculation result indicated by the solid line. That is, the graph of the calculation result indicated by the solid line shows that the directivity of the echo of the point reflection source is about 2% sharper at 50% of the 6 dB drop of the echo.

"D _W " described in the upper right of both figures is 6 dB.
A value calculated by the following equation is a theoretical equation of the beam diameter of the drop, d _W / 2 is the beam radius. d _W = 1.029 × wavelength × water distance / diameter of the oscillator (2) “50%” described under d _W is such that the echo height indicated by the solid line is 50% of the maximum value. Probe 4 up to
Is the moving distance X of. Looking at the numerical values set forth in FIGS. 6 and 7, only d _W / 2 and 0.7μm are different.
Also, at 10% of the 20 dB drop, it matches the directivity of the echo of the point reflection source. When the echo height is less than about 7%, it does not match, but at such a low echo height, the directivity is not usually evaluated.
Practically no problem.

Further, considering that the thinner the plate-like target 3 may be, the more accurate the directivity can be evaluated, the thickness t
FIG. 7 shows the calculation results when a plate-like target 3 having a thickness of 0.002 mm was used, and the thickness t = 0.0 shown in FIG.
The result was almost the same as the calculation result when the 1 mm plate-shaped target 3 was used.

Therefore, in order to measure an ultrasonic wave of 50 MHz, a plate-shaped target 3 having a thickness t of 0.01 to 0.02 mm is practically sufficient. Further, as the plate-like target 3 becomes thicker, the calculation curve of directivity gradually widens. For example, in the case of an ultrasonic wave of 50 MHz, when the thickness of the plate-like target 3 is 0.03 mm, it coincides at 50%, but a deviation occurs at around 10%.

Further, as shown in FIG.
When the thickness is 0.04 mm, a shift of about 6% occurs near 50%. When the thickness of the plate-like target 3 is 0.1 mm as shown in FIG. Therefore, in the case of the plate-like target 3 having a thickness of 0.1 mm, 50M
It turns out that the ultrasonic wave of Hz cannot be measured.

Since the cross section of the ultrasonic wave is circular, the directivity of the ultrasonic wave is represented as a symmetrical curve. In FIGS. 6 to 9, only the right half is shown, and the graph of the left half is shown. Omitted. Further, the upper end surface 3a of the plate-like target 3
Does not necessarily have to be a perfect plane.
As shown by 0, even when the upper end face 3a has a curved shape and the projection 3b projects on one side of the upper end face 3a, the ultrasonic wave can be reflected without any trouble. In particular, the projections 3b may be generated on the upper end surface 3a depending on the processing method. However, when the thickness of the plate-like target 3 is extremely thin as 0.01 mm, it is difficult to remove the projections 3b.

FIG. 10 is a photomicrograph in which the upper end face 3a is enlarged, and the length of the projection 3b is about 10 μm. The upper end surface 3a of the plate target 3 is desirably a flat surface as shown in FIG. However, when the thickness of the plate-shaped target 3 is reduced, when the target is processed to a predetermined size, the target may have a shape having a protrusion 3b as shown in FIG. For example, the wavelength of 50 MHz ultrasonic wave in water is 30 μm, and 1/10 of the wavelength is 3 μm.
If the deformation is less than m, it is considered that there is no problem. Further, the same result can be obtained even when the thickness of the plate-like target 3 is 0.01 to 0.02 mm.
Can be ignored.

FIG. 11 is a graph showing the measurement results of the directivity of the probe 4 obtained by receiving the echo reflected from the plate target 3 having a thickness of 0.01 mm. In FIG. 11, the broken line indicates the result of the first experiment, and the solid line indicates the result of the second experiment. The reason why the first experiment result and the second experiment result are shifted to the left and right is that when the probe 4 is moved in the X direction, the backlash of the gear of the XY direction drive unit 6 has an effect. is there.

It can be said that the first graph I and the second graph II have almost the same curve except for a low echo portion. For example, at 50%, the beam diameter (the dimension in the horizontal direction of the graph) is measured to be 78 μm from Graph I and 77 μm from Graph II.

The beam diameter shown on the left side in FIG. 11 is the result of measuring the beam diameter by the 6 dB drop method after measuring the directivity curve. This beam diameter is 75 μm
± 1 μm. This value is calculated by the theoretical value of 60.9 μm of the beam diameter d _W by the 6 dB drop method calculated by the above equation (2).
1.23 times m. This means that the actual frequency is 50M
Hz, so that the frequency is 1 / 1.2 of 50 MHz.
3, ie, 50 / 1.23 ≒ 41 MHz.

FIG. 12 is a graph showing variations in measured values of the beam diameter. When the water distance La was 12.7 mm, the beam diameter of the 6 dB drop of the probe 4 was measured 26 times. As a result, the beam diameter was 78.9 to 88.9 with one exception.
It varies to 1.7 μm and the beam diameter is 80.4 ±
1.5 μm. From this result, it can be seen that the measurement accuracy when the plate-like target 3 is used is sufficiently ensured.

FIG. 13 is a graph showing the calculation result of the echo height at 10 MHz using the plate-like target 3 having a thickness of 0.03 mm. When the probe 4 of 10 MHz is used, as a result of calculating the influence of the thickness of the plate-shaped target 3, the same curve as the graph shown in FIG. 13 is obtained when the thickness of the plate-shaped target 3 is 0.03 mm or less. It has been found that the target 3 can be used without any practical problems up to a thickness of 0.08 mm.

When measuring the directivity of the probe 4 at 10 MHz, the beam diameter becomes about 230 μm.
The thickness of the plate-shaped target 3 should be considerably thicker than in the case of MHz. It should be noted that the thicker the plate-like target 3, the higher the echo height and the better the SN ratio, which is convenient for measuring the beam diameter. The echo height is proportional to the thickness of the plate-shaped target 3 to a certain limit, but the upper limit of the thickness of the plate-shaped target 3 is determined in relation to the wavelength of the ultrasonic wave.

FIG. 14 is a graph showing a calculation result of the echo height when the plate-like target 3 having a thickness of 0.1 mm is used. A calculation result in the case where the directivity of the probe 4 of 10 MHz is measured using the plate-shaped target 3 having a thickness of 0.1 mm indicates that the probe 4 can be used without any problem except for -20 dB.

FIG. 15 is a graph showing the results of measuring the directivity of the probe 4 at 10 MHz using the plate-like target 3 having a thickness of 0.03 mm. In FIG. 15, the solid line is a graph of the first experimental result, and the broken line is a graph of the second experimental result.

In this case, the first and second graphs almost coincide with each other because the beam diameter is larger than in the case of FIG. 11 and the backlash of the gear of the XY direction drive unit 6 has no effect. ing. Thereafter, when the beam diameter was measured 12 times, the beam diameter was 277.8 ± 1.5 μm.

The beam diameter of the probe 4 is calculated to be 233 μm according to the above equation (2). Since the ratio between the calculated value and the experimental value is 277/233 = 1.19, there is only a 19% difference between the calculated value and the experimental value. 1
Since the 0 MHz probe 4 is for a narrow band, it can be determined that the calculated value and the experimental value almost match.

Therefore, when measuring the directivity of the probe 4 of 10 MHz, it is possible to use the plate-like target 3 having a thickness of 0.03 to 0.1 mm. 3 can cover the range of 10 to 50 MHz, and there is no need to frequently replace the plate-like target 3.

In the above-described embodiment, the case where the directivity is measured by moving the probe 4 in the X direction has been described as an example. However, the present invention is not limited to this. Needless to say, the target 3 may be moved in the X direction.

[0050]

As described above, according to the first aspect of the present invention, the reflection surface of the target has a predetermined thickness corresponding to the wavelength of the ultrasonic wave and extends longer than the beam diameter of the ultrasonic wave. Since it is formed, it is possible to accurately measure the intensity distribution of high-frequency ultrasonic waves, and to measure the beam diameter of high-frequency ultrasonic waves with high accuracy. In addition, by forming the target in a thin plate shape, the linear reflecting surface can be processed with high precision, so that a target corresponding to a high frequency wavelength can be manufactured.

According to the second aspect of the present invention, the ultrasonic wave is transmitted from a direction substantially perpendicular to the narrow end face of the target, the ultrasonic wave reflected on the end face of the target is received, and the beam diameter of the ultrasonic wave is reduced. Since the measurement is performed, the intensity distribution of the high-frequency ultrasonic wave can be accurately measured, and the beam diameter of the high-frequency ultrasonic wave can be measured with high accuracy.

According to the third aspect of the present invention, the plate-like target having a narrow reflection surface formed in a straight line is held by the holder, and the ultrasonic wave is applied from a direction substantially perpendicular to the reflection surface of the plate-like target. Is transmitted, the reflection efficiency of the ultrasonic wave is enhanced, the intensity distribution of the high-frequency ultrasonic wave can be measured accurately, and the beam diameter of the high-frequency ultrasonic wave can be measured with high accuracy.

[Brief description of the drawings]

FIG. 1 is a front view showing a configuration of an embodiment of a beam diameter measuring device of an ultrasonic point focusing water immersion probe according to the present invention.

FIG. 2 is a side view of the beam diameter measuring device of the ultrasonic point focusing water immersion probe.

FIG. 3 is a diagram illustrating an example for explaining an operation when measuring the directivity of an ultrasonic wave transmitted from a probe.

FIG. 4 is a diagram illustrating an example of a state in which a plate-like target is held on a side surface of a holder.

FIG. 5 is a principle diagram for explaining a method of calculating a scan graph of an upper end surface of a plate-like target.

FIG. 6 is a graph showing a calculation result of an echo height when a plate-like target having a thickness t = 0.01 mm is used.

FIG. 7 is a graph showing a calculation result of an echo height when a plate-like target having a thickness t of 0.002 mm is used.

FIG. 8 is a graph showing a calculation result of an echo height when a plate-like target having a thickness t = 0.04 mm is used.

FIG. 9 is a graph showing a calculation result of an echo height when a plate-like target having a thickness t = 0.1 mm is used.

FIG. 10 is an enlarged view showing a modification of the shape of the upper end surface of the plate-like target in an enlarged manner.

FIG. 11 is a graph showing measurement results of directivity of a probe obtained by receiving an echo reflected from a plate-like target having a thickness of 0.01 mm.

FIG. 12 is a graph showing variations in measured values of a beam diameter.

FIG. 13 is a graph showing a calculation result of a 10 MHz echo height using a plate-like target having a thickness of 0.03 mm.

FIG. 14 is a graph showing a calculation result of an echo height when a plate-like target having a thickness of 0.1 mm is used.

FIG. 15 is a graph showing the results of measuring the directivity of a 10 MHz probe using a plate-like target having a thickness of 0.03 mm.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Beam diameter measuring device 2 Water tank 3 Plate target 4 Probe 5 Holder 6 XY direction drive part 7 Elevating mechanism

Claims (3)

[Claims] 1. A target for measuring a beam diameter of an ultrasonic point focusing water immersion probe having a reflecting surface for reflecting an ultrasonic wave transmitted from a probe in water, wherein the reflecting surface has a wavelength of the ultrasonic wave. A beam diameter measuring target for an ultrasonic point-focusing water immersion probe, which has a corresponding predetermined thickness and is formed so as to extend longer than the ultrasonic beam diameter. 2. An ultrasonic point-focusing immersion for measuring a beam diameter of an ultrasonic wave by reflecting an ultrasonic wave transmitted from the probe to a target while moving either a probe or a target in water. In the method of measuring the beam diameter of the probe, the target is formed in a plate shape having a predetermined thickness corresponding to the wavelength of the ultrasonic wave, and the ultrasonic wave is transmitted from a direction substantially perpendicular to a narrow end surface of the target. Receiving the ultrasonic wave reflected by the end face of the target and measuring the beam diameter of the ultrasonic wave. 3. An ultrasonic point-focusing water immersion probe beam diameter measuring device for measuring an ultrasonic beam diameter by reflecting ultrasonic waves transmitted from a probe in water, wherein the beam diameter corresponds to the wavelength of the ultrasonic wave. A plate-shaped target having a narrow reflecting surface extending linearly and formed in a plate-like shape having a predetermined thickness, and being provided below the probe and formed in a linear shape of the plate-shaped target. A holder for holding the plate-shaped target so that ultrasonic waves are transmitted from a direction substantially perpendicular to the reflected surface, and a beam diameter measurement of the ultrasonic point focusing water immersion probe. apparatus.