JPH04283660A - Ultrasonic microscope device - Google Patents

Abstract

PURPOSE:To obtain an ultrasonic microscope for performing a point focusing and a line focusing with one probe without changing the probe. CONSTITUTION:An acoustic lens of a probe is constituted by a first lens 41 where a center perimeter lens surface is constituted by a spherical recessed surface 42 and a second lens 46 where a center lens surface is constituted by a cylindrical recessed surface 47. A oscillator of the probe is constituted by a first oscillator 43 which is provided on the lens surface 42 of the first lens 41 and generates ultrasonic which is point-focused and a second oscillator 48 which is provided at a position opposing the lens surface 47 of the second lens 46 and generates ultrasonic which is line-focused. Then, a synthesis means for synthesizing an output signal of a receiver and a specified transmission signal is provided.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic microscope apparatus for evaluating the physical properties of a sample using ultrasonic waves, and more particularly to an ultrasonic microscope apparatus suitable for measuring anisotropy at any point on a sample.

0002

2. Description of the Related Art An ultrasonic microscope device is used as a device for inspecting the physical properties of the surface layer of an object (sample) to be inspected, the presence or absence of defects inside the sample, and the like. Such an ultrasonic microscope device will be explained with reference to FIG. FIG. 9 is a block diagram of a conventional ultrasound microscope device. In the figure, reference numeral 1 denotes an ultrasonic probe, in which an ultrasonic transducer is placed on the upper surface of a lens, and a concave surface of the lens is formed at the lower end. 2 is the ultrasound medium (e.g. water);
3 is a sample, and 4 is a sample stage. 5 is a transmitter, which outputs a burst-like electrical signal; 6 is a receiver, which receives an electrical signal sent from the ultrasound probe 1 via a directional coupler 7, which will be described later; Amplify as appropriate. The directional coupler 7 transmits the burst wave signal from the transmitter to the ultrasound probe 1.
On the other hand, the electrical signal from the ultrasound probe 1 is sent to the receiver 6.
The function is to switch to send to. A peak detector 8 detects the peak value of the output signal of the receiver 6. Reference numeral 9 denotes an A/D converter, which A/D converts the electrical signal received by the receiver 6 based on the peak value detected by the peak detector 8. Reference numeral 10 denotes an arithmetic controller composed of a microcomputer, which performs necessary calculations and controls based on signals from the ultrasonic probe 1, and also controls the ultrasonic probe 1.
Outputs a command signal for movement in the Z-axis direction. Drive controller 11
drives the Z-axis moving device 12 based on the command signal. The Z-axis drive device 12 moves the ultrasonic probe 1 in the Z-axis direction, that is, in the direction perpendicular to the sample 3, in response to a command signal from the drive controller 11. 13 is a CRT display, for example, which displays the ultrasonic measurement results on a screen. In such an ultrasound microscope, first, a burst voltage from a transmitter 5 is applied to the probe 1 via a directional coupler 7, and the ultrasonic waves generated thereby are transmitted via a medium 2 to a sample stage 4. Sample 3 above
At the same time, the reflected wave reflected from the sample 3 is converted into an electrical signal by the probe 1 via the same route, and this electrical signal is received by the receiver 6 via the directional coupler 7. . The receiver 6 amplifies the received electrical signal appropriately and sends it to the peak detector 8, and the peak value detected here is detected by the A/D.
The signal is converted into a digital signal by a converter 9, subjected to necessary processing by an arithmetic controller 10, and the result is displayed on a CRT display 13. During this time, the arithmetic controller 10
Then, the distance of the probe 1 from the sample 3 is controlled.

FIG. 10 is an enlarged explanatory view showing the manner in which the ultrasonic beam is reflected when the ultrasonic beam is irradiated onto the surface of the sample 3 in a defocused state. As shown in FIG. 10, when the ultrasonic wave is irradiated from the probe 1 to the sample 3, the sample 3
Vertical reflected waves from the surface and surface acoustic waves propagating on the surface of sample 3 are reflected to probe 1, and these reflected waves are shown in Figure 1.
As shown in the waveform diagram 1, the vertical reflected wave a is detected first, and then the surface acoustic wave b, which has a long propagation path, is detected later. These reflected waves interfere with the probe 1 and are detected as interference waves. When both waves are in phase, the amplitude of the interference wave becomes large as shown by waveform c, and when they are in opposite phase, the amplitude becomes small as shown by waveform d. The phase shift between the two waves varies depending on the position of the probe 1 with respect to the sample 3. Then, the in-phase and anti-phase are sequentially repeated in accordance with changes in the distance between the probe 1 and the sample 3. That is, driving the Z-axis moving device 12 causes a phase change between the vertically reflected wave and the surface acoustic wave, and the amplitude of the output signal from the receiver 6 changes. When such an electrical signal is processed by the arithmetic controller 10 via the A/D converter 9 and displayed on the display 13, a curve having a constant period is obtained as shown in FIG. This curve is a so-called V(Z) curve, with the position of the probe 1 on the horizontal axis and the received signal level of the interference wave on the vertical axis. The period and signal level have a predetermined relationship with the propagation velocity and attenuation of the surface acoustic wave. Therefore, by measuring the period and signal level, the propagation velocity and attenuation can be determined, and the physical properties of the sample 3 can be evaluated based on these.

[0004] Incidentally, as a probe used in such an ultrasonic inspection, a point focusing type probe as shown in FIGS. 13 to 15 is generally used. FIG. 13 is a top view of the point focusing type probe, FIG. 14 is a side view thereof, and FIG. 15 is a bottom view thereof. That is, in this point-focusing type probe, as shown in FIG. 13, a circular vibrator 22 to which a lead wire 21 is connected is attached to the center of the upper surface of an acoustic lens 20, and as shown in FIGS. 14 and 15. This acoustic lens 20 has a hemispherical concave surface 23 formed on its lower end surface. There are two methods for observing the sample 3 having a metal particle structure as shown in the micrograph of FIG. 16 using this point-focusing probe:
There is a method using a (Z) curve, but since the latter responds more sensitively, it is more often observed by measuring the difference in surface acoustic wave velocity. After observing the entire structure of sample 3 in this way, if you want to further quantitatively understand the physical properties of each structure, the structure at any position on sample 3 can be measured using a V(Z) curve. However, when it comes to understanding the anisotropy of tissues, point-focusing probes cannot provide sufficient information. The reason for this is that the surface acoustic waves excited by the point-focusing probe have components in all directions within the plane, as shown by the arrow in the surface acoustic wave propagation region of the sample surface 3 indicated by the symbol A in FIG. This is because a V(Z) curve containing a mixture of surface acoustic wave velocities in all directions of the anisotropic tissue is obtained, making analysis difficult. Therefore, when understanding tissue anisotropy, remove the point-focusing type probe from the device and replace it with a line-focusing type probe whose emitted ultrasonic waves are directional. Irradiation is being performed. 18 to 20 are a top view, a side view, and a bottom view of the line focusing type probe, and FIG. 21 is a sectional view taken along line D'-D' in FIG. 19. This line focusing type probe is equipped with a rectangular vibrator 32 to which a lead wire 31 is connected, for example, to the center of the top surface of an acoustic lens 30, as shown in FIG. 18, and as shown in FIGS. 19, 20 and 21. The acoustic lens 30 has a semi-cylindrical concave surface 33 formed on its lower end surface. The surface acoustic waves excited by this line focusing probe are generated because the concave surface 32 of the lower end surface of the acoustic lens 30 is semi-cylindrical, as shown by the arrow in the surface acoustic wave propagation region of the sample indicated by the symbol B in FIG. Since the waves are propagated only in a specific direction (the radial direction of the semi-cylinder), it is possible to measure the surface acoustic wave velocity in each direction of the anisotropic tissue.

[0005]

[Problems to be Solved by the Invention] In the conventional ultrasonic microscope device described above, when evaluating the physical properties of a sample, a point-focusing probe is used to observe the entire image, and the anisotropy of the tissue is observed. In some cases, the point-focusing probe is removed and replaced with a line-focusing probe. However, since the actual tissue to be measured is a minute region on the order of μm, there is a problem in that it is difficult to measure anisotropy at the position that is truly desired due to mounting errors when replacing the probe. In order to avoid this, if a line focusing type probe is used from the beginning, the following problems will occur. That is, since the ultrasonic waves from the line focusing probe have directionality, when observing the entire image of the tissue of sample 3, the direction of surface acoustic wave propagation in surface acoustic wave propagation region B is determined as shown in FIG. If it is in the X direction, an image expressing the difference in surface acoustic wave velocity in this direction will be obtained, but since rectangular region B has a considerable range and straddles the tissue boundary, the resulting The resulting image is an image in which the tissue boundaries in the X direction are not clearly shown, as shown in FIG. On the other hand, if the surface acoustic wave propagation direction in region B is in the Y direction as shown in FIG. 24, the obtained image will be an image in which the tissue boundaries in the Y direction do not clearly appear as shown in FIG. 26. In any case, using a line focusing probe will result in a tissue image that is different from the overall tissue image that is originally desired. An object of the present invention is to solve the above-mentioned problems of the prior art and to provide an ultrasonic microscope device that can perform point focusing and line focusing with one probe without replacing the probe. be.

[0006]

[Means for Solving the Problems] In order to achieve the above objects, the present invention provides a probe comprising an acoustic lens and a vibrator, a transmitter that excites the vibrator, and a transmitter that excites the vibrator. and a receiver for receiving reflected ultrasound waves, wherein the acoustic lens includes a first lens having a peripheral lens surface having a spherical concave surface, and a center lens surface having a cylindrical concave surface. The probe includes a first transducer that is provided on the lens surface of the first lens and generates a point-focused ultrasonic wave; A second lens is provided at a position facing the lens surface and generates line-focused ultrasonic waves.
The present invention is characterized in that it is composed of a vibrator, and further includes a synthesizing means for synthesizing the output signal of the receiver and a predetermined transmission signal.

[0007]

[Operation] When observing the entire image when evaluating the physical properties of a sample, a voltage is applied to the first vibrator, and the ultrasonic waves converted here are directly irradiated onto the sample. Then, the reflected wave from the sample is converted into an electrical signal by the same first oscillator, this electrical signal and a predetermined transmitted signal are synthesized by a synthesizing means, and a V(Z) curve is obtained from the interference wave obtained here. . On the other hand, when measuring the anisotropy of the sample, a voltage is applied to the second vibrator, and the ultrasonic waves converted here are irradiated from the cylindrical concave surface to the sample. Then, the reflected wave from the sample is converted into an electrical signal by the same second oscillator, and the vertical reflected wave in this electrical signal and the surface acoustic wave are caused to interfere with each other to obtain a V(Z) curve.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below based on the illustrated embodiments. 1 to 4 are diagrams showing the configuration of an ultrasound probe used in an ultrasound microscope device according to an embodiment of the present invention,
Figure 1 is a top view, Figure 2 is a side view, Figure 3 is a bottom view, Figure 4 is Figure 1.
FIG. 2 is a cross-sectional view taken along line DD shown in FIG. In the figure, 40 indicates an ultrasonic probe. 41 is a first acoustic lens; 42 is a spherical concave surface formed on the lower end surface of the acoustic lens 41; 43 is a ring-shaped first vibrator provided on the spherical concave surface 42 to which a lead wire 44 is connected; 45 is an opening formed vertically through the center of the spherical concave surface 42. 46 is a second acoustic lens built into the center of the spherical concave surface 42, that is, the aperture 45; 47 is a cylindrical concave surface formed at the lower end surface of the second acoustic lens 46; 48 is a second acoustic lens 46 is a rectangular second vibrator provided at a position facing the cylindrical concave surface 47 on the upper surface thereof, and to which a lead wire 49 is connected. Note that the second acoustic lens 46 may be assembled into the aperture 45 of the acoustic lens 41 by a screwing method, a fitting method, or an adhesive method, but it may also be integrally molded from the beginning.

FIG. 5 is an explanatory diagram illustrating the state when ultrasonic waves are transmitted from the first transducer 43. In FIG. 5, parts that are the same as those in FIG. When a voltage is applied to the first transducer 43 shown in FIG. 5 via the lead wire 44, the ultrasonic beam 50 emitted from the first transducer 43 is directed toward the sample 3 as shown in FIG. Emitted while being focused.

FIG. 6 shows the area within the two-dot chain line C in FIG. 5, that is, sample 3.
FIG. 3 is an enlarged explanatory diagram showing a reflection mode when ultrasonic waves are irradiated upward in a defocused state. In FIG. 6, the same parts as those shown in FIG. 5 are given the same reference numerals. As shown in FIG. 6, the ultrasonic beam 50 obtained by the first transducer 43 becomes a ring-shaped ultrasonic beam 5 when defocused.
1 and enters the sample 3. At this time, the ultrasonic beam 5
A surface acoustic wave 52 is excited within the irradiation range of 0, but since there is no vertical reflected wave near the center of the acoustic lens 40, no interference occurs and a V(Z) curve cannot be obtained. Therefore, in this embodiment, a V(Z) curve is obtained by causing electrical interference using a reference signal source and a combining circuit, which will be described later. Note that when an ultrasonic wave is emitted from the second transducer 48 placed at the center of the upper surface of the first acoustic lens 46, the ultrasonic wave is The light propagates toward the cylindrical concave surface 47 and is further focused onto the sample 3 by the cylindrical concave surface 47 .

FIG. 7 is a block diagram of the ultrasonic microscope apparatus of this embodiment. In the drawings, the same members, mechanisms, etc. as shown in FIGS. 1 and 9 are denoted by the same reference numerals, and explanations thereof will be omitted. A reference signal source 60 emits a reference signal, for example a sine wave signal of a predetermined frequency. 61 is a synthesis circuit;
The reference signal from the reference signal source 60 and the electrical signal received by the receiver 6, that is, the electrical signal obtained by converting the reflected wave from the sample 3 by the probe 40, are combined. The burst voltage output from the transmitter 5 is transmitted to the first vibrator 4 via the directional coupler 7.
3, the first vibrator 43 emits an ultrasonic wave, which directly propagates through the medium 2 and is irradiated onto the sample 3 on the sample stage 4. The first vibrator 43 converts the reflected wave reflected from the sample 3, that is, the surface acoustic wave, into an electrical signal, and the converted electrical signal is received by the receiver 6 via the directional coupler 7. Ru. Next, the electrical signal received by the receiver 6 is sent to a combining circuit 61, where it is combined with a reference signal transmitted from a reference signal source 60 to obtain an interference wave. This interference wave is sent to a peak detector 8 to detect its peak value, and this peak value is further converted into a digital signal by an A/D converter 9, and then an arithmetic controller 10
is input. As the probe 40 moves in the Z-axis direction, the phase of the output signal of the receiver 6 changes in accordance with the movement, but since the reference signal maintains the same phase, the synthesis circuit 6
The interference wave signal from 1 is repeatedly interfered between the same phase and the opposite phase, and becomes a signal whose level of the interference wave signal gradually changes. Based on the signals thus obtained, the arithmetic controller 10 performs predetermined calculations and controls, and the results are displayed on the CRT display 13. This allows the physical properties of the tissue to be evaluated. Further, when the burst voltage output from the transmitter 5 is applied to the second vibrator 48 via the directional coupler 7, the second vibrator 48 emits an ultrasonic wave, and this ultrasonic wave The sample 3 on the sample stage 4 is irradiated via the acoustic lens 46 of No. 2 and the medium 2 . Then, the second vibrator 44 converts the reflected wave reflected from the sample 3, that is, the interference wave obtained by interfering the vertical reflected wave and the surface acoustic wave, into an electrical signal, and the converted electrical signal is transmitted to the directional coupler. 7 and is received by the receiver 6. Next, the electrical signal received by the receiver 6 is sent to the peak detector 8 via the combining circuit 61, and its peak value is detected. In this case, the oscillation of the reference signal source 60 is stopped and its output is zero. The detected peak value is further sent to an A/D converter 9.
After being converted into a digital signal, the signal is input to the arithmetic controller 10. Here, the arithmetic controller 10 performs predetermined calculations and controls, and the results are displayed on the CRT display 13. This makes it possible to understand the anisotropy of the tissue. Therefore, in this embodiment, when a point focusing function is required, a burst voltage is applied to the ring-shaped first vibrator 43, and the reflected wave (that is, surface acoustic wave) reflected from the sample 3 is Convert it to an electrical signal and send it to the synthesis circuit 6
1, the interference wave is synthesized with the reference signal from the reference signal source 60, and the interference wave is processed by the control calculator 10. If a line focusing function is required, a rectangular The second transducer 48 is excited, and the reflected wave obtained via the cylindrical concave surface 47 is converted into an electrical signal, which is processed by the control calculator 10 as it is, so there is no need to replace the probe. Point focusing and line focusing can be performed without any problems, and as a result, it becomes possible to accurately evaluate the physical properties of the sample 3.

FIG. 8 is a block diagram of an ultrasonic microscope apparatus according to another embodiment of the present invention. In the figure, the same members, mechanisms, etc. as shown in FIGS. 1 and 4 are denoted by the same reference numerals. The detailed explanation will be omitted. 70 is a continuous oscillator that continuously transmits a reference signal, for example, a sine wave signal of a predetermined frequency. A waveform extractor 71 extracts a required burst voltage from the reference signal transmitted from the continuous oscillator 70 and outputs it. A transmitter is composed of a continuous oscillator 70 and a waveform cutter 71. The burst voltage output from the waveform cutter 71 is applied to the first vibrator 43 via the directional coupler 7, and this vibrator 43 converts the reflected wave reflected from the sample 3 into an electrical signal. , the converted electrical signal is received by the receiver 6 via the directional coupler 7, the output signal of the receiver 6 is combined with the reference signal from the continuous oscillator 70 in the combining circuit 61, and the interference signal is removed from the combining circuit 61. A wave signal is output. The subsequent operations are the same as in the previous embodiment. In this way, in this embodiment, the reference signal is obtained from the continuous oscillator 70 that constitutes the transmitter, so in addition to the effects of the previous embodiment,
This has the effect of eliminating the need to provide a separate reference signal source.

[0013]

As described above, according to the present invention, a spherical concave surface is formed at the lower end of the first lens of an ultrasound probe, and
A second acoustic lens having a cylindrical concave surface is incorporated into the first lens, and a first vibrator is further provided on the spherical concave surface, and a second vibrator is provided at a position opposite to the cylindrical concave surface of the second acoustic lens. When measuring the reflected wave from the sample with the first transducer, the reflected wave is combined with the reference signal in the synthesis circuit, so one probe can be used without replacing the probe. Point focusing and line focusing can be performed with the tentacles.

[Brief explanation of the drawing]

FIG. 1 is a top view of an ultrasound probe used in an ultrasound microscope apparatus according to an embodiment of the present invention.

FIG. 2 is a side view of FIG. 1;

FIG. 3 is a bottom view of FIG. 1;

FIG. 4 is a cross-sectional view taken along line DD shown in FIG. 1;

FIG. 5 is an explanatory diagram illustrating a state when ultrasonic waves are transmitted from a first rectangular transducer.

FIG. 6 is an enlarged explanatory diagram showing a reflection mode when ultrasonic waves are irradiated onto a sample in a defocused state.

FIG. 7 is a block diagram of an ultrasound microscope apparatus according to a first embodiment of the present invention.

FIG. 8 is a block diagram of an ultrasound microscope apparatus according to a second embodiment of the present invention.

FIG. 9 is a block diagram of a conventional ultrasound microscope device.

FIG. 10 is an enlarged explanatory diagram showing a state when ultrasonic waves are irradiated onto a sample in a conventional ultrasonic probe.

FIG. 11 is a diagram showing an example of a vertical reflected wave, a surface acoustic wave, and an interference wave.

FIG. 12 is a diagram showing an example of a V(Z) curve.

FIG. 13 is a top view of a conventional point focusing probe.

FIG. 14 is a side view of FIG. 11;

FIG. 15 is a bottom view of FIG. 11;

FIG. 16 is a diagram showing an example of a microscopic photograph of a metal surface.

FIG. 17 is an enlarged explanatory diagram showing the reflection mode when ultrasonic waves are irradiated onto a sample in a conventional point focusing probe.

FIG. 18 is a top view of a conventional line focusing probe.

FIG. 19 is a side view of FIG. 16;

FIG. 20 is a bottom view of FIG. 16;

FIG. 21 is a cross-sectional view taken along line D'-D' in FIG. 17;

FIG. 22 is an enlarged explanatory diagram showing the reflection mode when ultrasonic waves are irradiated onto a sample in a conventional line focusing probe.

FIG. 23 is an explanatory diagram illustrating a measurement mode when the surface acoustic wave propagation direction of a conventional line focusing probe is in the X direction.

FIG. 24 is an explanatory diagram illustrating a measurement mode when the surface acoustic wave propagation direction of a conventional line focusing probe is in the Y direction.

FIG. 25 is an explanatory diagram showing a specific example of a tissue image that is the result of observing the tissue of a sample when the surface acoustic wave propagation direction of a conventional line focusing probe is in the X direction.

FIG. 26 is an explanatory diagram showing a specific example of a tissue image that is the result of observing the tissue of a sample when the surface acoustic wave propagation direction of a conventional line focusing probe is in the Y direction.

[Explanation of symbols]

41 First acoustic lens 42 Spherical concave surface 43 First oscillator 46 Second acoustic lens 47 Cylindrical concave surface 48 Second oscillator

Claims (6)

[Claims] 1. An ultrasonic probe comprising an acoustic lens and a transducer, a transmitter that excites the transducer, and a receiver that receives reflected waves of ultrasound generated by excitation of the transducer. In the acoustic microscope device, the acoustic lens is
a first lens having a spherical concave lens surface around the center;
and a second lens having a central lens surface configured as a cylindrical concave surface, and the transducer is a first transducer that is provided on the lens surface of the first lens and generates point-focused ultrasonic waves. , and a second lens provided at a position facing the lens surface of the second lens and generating line-focused ultrasonic waves.
What is claimed is: 1. An ultrasonic microscope apparatus comprising a vibrator, and further comprising a synthesizing means for synthesizing the output signal of the receiver and a predetermined transmission signal. 2. The ultrasonic microscope apparatus according to claim 1, wherein the first vibrator has a ring shape along the spherical concave surface. 3. The ultrasonic microscope apparatus according to claim 1, wherein the second transducer is a rectangular transducer. 4. The ultrasonic microscope apparatus according to claim 1, wherein the second lens is integrated by tightly fitting into an aperture formed in the first lens. 5. The ultrasonic wave generator according to claim 1, wherein the predetermined transmission signal to be synthesized with the output signal of the receiver by the synthesizing means is a sine wave of a predetermined frequency output from a reference signal source. Sonic microscope equipment. 6. The ultrasonic transmitter according to claim 1, wherein the predetermined transmission signal to be combined with the output signal of the receiver by the combining means is an output signal of a continuous transmitter constituting the transmitter. Sonic microscope equipment.