JPS60115848A - Ultrasonic microscope device - Google Patents

Abstract

PURPOSE:To measure and display an ultrasonic wave image and material characteristics of a sample automatically in a short time by calculating the Rayleigh wave speed and longitudinal and lateral wave speeds of the sample, and calculating and displaying the elastic constant of the sample by using said speed values. CONSTITUTION:While the sample 21 is moved in the axial direction of an acoustic lens 18, the relation of reflected wave intensity of movement distance is measured to calculate the speed of the Rayleigh wave propagating in the sample from the distance interval between peaks of reflected wave intensity and also calculates the speed of the longitudinal wave propagating in the sample from the time interval between peaks of a multiecho wave from the sample 21. Further, the speeds of the Rayleigh wave and longitudinal wave are used for arithmetic to calculate and display or record the elastic constant of the sample 21. Therefore, not only the ultrasonic wave image of the sample, but also material characteristics are measured and displayed automatically in a short time.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention provides not only an ultrasonic image of a sample but also an elastic constant of the sample.
The present invention relates to an ultrasonic microscope device configured to be able to measure and grasp material properties.

[Technical background of the invention and its problems]

A mechanical scanning ultrasound microscope is a device that uses ultrasound instead of light to observe the microscopic structure of an object. In principle, this ultrasonic microscope mechanically scans the sample surface with a narrowly focused ultrasonic beam, collects the ultrasonic waves scattered by the sample, converts them into electrical signals, and transmits the signals to a cathode ray tube. The image is displayed two-dimensionally on the display screen to obtain a microscopic image.

As the ultrasonic waves to be scanned, an ultrafine frequency beam of about 100 MHz to IGHz is used, and a resolution of about 10 μm to 1 μm can be obtained. Furthermore, by using a beam with a frequency higher than the above, it is possible to further increase the resolution, and there is also the advantage that an internal image of an object can be observed using ultrasonic waves.

The configuration depends on how the ultrasound is detected; in other words, there are cases where ultrasonic waves that have passed through the sample while being scattered or attenuated are detected, and cases where ultrasonic waves that have been reflected due to differences in the acoustic properties within the sample are detected. Depending on the type, they are divided into transmissive type and reflective type.

Figure 1 is a configuration diagram of a reflective ultrasonic beam. This signal is converted into an ultrasonic wave, and this is attached to an acoustic lens 4 made of an ultrasonic propagation material such as sapphire, which is used for both transmitting and receiving waves. radiates inward from one side of the

The ground surface of this acoustic lens 4 is hollowed out into a spherical shape to form a spherical lens section 4a, and a sample holding table 5 is arranged opposite to the spherical lens section 4a. Water 6, which is a sound field medium, is interposed between the acoustic lens 4 and the holding table 5, and the sample 7 is attached to the holding table 5 at the focal point of the spherical lens portion 4a.

The holding table 5 is scanned by the scanning device 8 in the X and Y directions (the spherical lens part 4
(horizontal direction opposite to a). In addition, the holding stand 5
is movable up and down with respect to the spherical lens part 4a, and
It is possible to move in any direction. Of course, it is also possible to move the acoustic lens 4 in the X, Y, and Z directions instead of the holding table 5. The scanning device 8 is controlled by a scanning circuit 9.

In the above configuration, the ultrasonic waves incident on the acoustic lens 4 from the piezoelectric transducer 3 are collected and reach the sample 7, and the reflected waves are collected again on the acoustic lens 4 and converted into electrical signals by the piezoelectric transducer 3. The signal is then supplied to the display device 10 through the directional coupler 2.

Conventional ultrasonic microscopes configured in this way can not only draw acoustic images by reflection or transmission of ultrasonic waves on the surface or inside of the sample, but also move the sample holder in the Z-axis direction and change the distance it moves. The intensity of the reflected wave is measured, and the velocity of the Rayleigh wave propagating within the sample is calculated based on the peak of the measured reflected wave and the distance between the peaks, and this velocity value is used to determine the sinusoidal properties of the sample. It was possible to see.

However, with conventional ultrasonic microscope devices, even if velocity values such as those mentioned above are obtained, it is not possible to specifically measure the elastic constants of the sample, and it is difficult to fully understand the material properties of the sample. It was possible.

[Purpose of the invention]

In view of the above-mentioned points, the present invention provides an ultrasonic microscope apparatus capable of measuring not only an ultrasonic image of a sample but also the material properties of the sample.

[Summary of the invention]

The ultrasonic microscope device of the present invention is equipped with a means for measuring the intensity of reflected waves with respect to the moving distance in the Z-axis direction of sample probe 1 and measuring the speed of Rayleigh waves of the sample, and also measures multiple echoes of the reflected waves. means to measure the velocity of the longitudinal wave of the sample by measuring the time interval of The method is configured such that the elastic constant of the sample can be displayed or recorded on a display device or a printer device.

[Embodiments of the invention]

Embodiments of the present invention will be described below based on the drawings.

FIG. 2 is a side view showing the configuration of the ultrasonic microscope used in the present invention, and FIG. 3 is an enlarged front view showing the vicinity of the holding table.

In FIG. 2, reference numeral 11 is an eyepiece lens, and 12 is a lens barrel. An objective lens 13 is arranged in a part of the lens barrel 12 and faces a holding table 15 on which a goniometer 14 is mounted. The microscope main body is held by mirror legs 16. The holding table 15 is held by a holding table moving device 17, and the acoustic lens 18 faces the goniometer 14.
It is supported by a vibrator 20 consisting of a voice coil. A light source 19 for epi-illumination is guided into the lens barrel 12 .

A sample 21 is placed on the goniometer 14. Note that the reference numeral 22 is a scanning knob for moving the holding table moving device 17. Further, as shown in FIG. 3, the acoustic lens 18 is supported by an arm 23 for transmitting vibrations from the exciter 20 to the acoustic lens 18. The exciter 20 receives an AC signal (a sine wave signal is used) applied by an external input signal generator (not shown).
As a result, the arm 23 vibrates in the longitudinal direction with a frequency of several I Q tlz. The acoustic lens 18 is scanned by receiving vibrations from the vibrator 20. The lower surface of the acoustic lens 1B is immersed in water 24.
It serves as a sound field medium between the sample 8 and the sample 21 to transmit ultrasonic waves with as little attenuation as possible. Sample 21
is held on the upper surface of the goniometer 14, and by turning a knob on the goniometer 14, the sample surface can be adjusted so as to be perpendicular to the axial direction of the nozzle 18. The goniometer 14 is provided with X- and Y-direction scanning knobs to enable two-dimensional scanning. The goniometer 14 is held by a holding table 15, and the holding table 15 is held by a holding table moving device 17, and can be moved up and down by rotating the holding table moving device scanning knob 22 to the right or left. It is designed to move in the direction.

FIG. 4 is a block diagram showing the electric circuit of the ultrasonic microscope device 4.

As shown in FIG. 4, the high frequency pulse generator 25 reaches a piezoelectric transducer 27.

The high frequency pulse signal is converted into an ultrasonic wave by the piezoelectric transducer 27 and propagated within the acoustic lens 18 . The ultrasonic wave is converted into a spherical wave by the spherical lens portion on the lower surface of the acoustic lens 18, passes through the water 24, and hits the sample 21. There, the ultrasonic wave is reflected from the sample 21, passes through the water 24 again, passes through the spherical lens part of the acoustic lens 18 again, is converted into a plane wave, reaches the piezoelectric transducer 27, and is further transmitted to the piezoelectric transducer 21 as an electrical signal. is converted to The electric signal generated in this manner is again guided to the circuit 1 to circuit 28 through the circulator 26. In the gate circuit 28, the gate is opened at the timing when the correct reflected signal returns so that only the correct reflected signal from the sample 21 can be extracted from among the ultrasonic reflected signals returned to the piezoelectric transducer 27. This makes it easy to extract the reflected signal. Specifically, the gate circuit 28 is used to reduce noise components due to unnecessary reflections from inside the acoustic lens 18 and the like. The correct reflected signal from the surface of the sample 21 obtained in this way is guided to the high frequency amplification circuit 29 for amplification, and then guided to the mixing circuit 30.

A local oscillation frequency signal from a local oscillator 31 enters the mixing circuit 30, and this signal and the reflected signal from the sample 21 are mixed, and as a result, the signal is converted to an intermediate frequency number 46. In this way, the noise component can be reduced by lowering the frequency and converting it into a 1/111 frequency lip to amplify it so that n < tc. The intermediate frequency signal is amplified by an intermediate frequency amplification circuit 32 and guided to a detection circuit 33 to extract the envelope of the burst wave, which is a signal from the sample 21, and then pass it to a blanking circuit 34. In the blanking circuit 34, only the reflected signal from the sample 21 is extracted, other important signals are cut off, and the signal is guided to a peak detection circuit 35c for peak detection. The detection output signals obtained in this manner are sequentially guided to a scan converter 36 and converted into a television signal, and an image is displayed on a television monitor 37 using the luminance signal. In this case, scan converter 3
6 temporarily stores the number of months of the detection output from the beam detection circuit 35.

Further, the scan converter is configured to operate in synchronization with the scanning period of the X-Y scanning mechanism 41 which can be controlled by the X deflection signal generation circuit 38 and the Y (+, it direction signal generation circuit 39 circuit 40) At step 36, the temporarily stored detection output signal mentioned above is read out at the television scanning cycle, and the readout signal is applied to the X and X deflection signal generation circuit 38.
．． Each synchronization signal from 39 is added to create a composite television signal, and this signal is sent to the television monitor 3T to obtain an ultrasonic image of the sample 21.

On the other hand, the above-mentioned loading device is provided with a Z-axis scanning mechanism 42 that can be controlled by a control circuit 40, so that the holding table 15 can be moved in the Z-axis direction and in the height direction. Therefore, a control signal is sent from the control circuit 40 to the Z-axis scanning mechanism 42, and while the holding table 15 is moved in the vertical direction according to commands from the control circuit 40, a reflected signal can be received from the sample 21. In this way, it is possible to measure the reflected signal output V with respect to the moving distance Z of the sample 21 in the Z-axis direction.

FIG. 5 is a diagram showing the relationship (hereinafter referred to as ■-Z curve) between the travel distance Z and the reflected signal output V (however, the figure shows the dead ash radiation output) measured as described above, Periodic peaks or valleys are formed in the reflected signal intensity depending on the moving distance Z.

In this curve, it is already known that by subtracting the pitch 1ΔZNI of the trough, the velocity of the Rayleigh wave of the sample 21 can be determined from the following equation.

1△ZN l = -Vn2 (f ・VH, O) ---
-(1) However, Vn is the velocity of the 17-ri wave of the sample, f is the frequency, and ■u2o is the sound velocity of water. In equation (1), since the frequency and the sound velocity of water are known, the velocity VR of the Rayleigh wave can be calculated.

On the other hand, reflected echo signals are reflected from the sample 21 and the acoustic lens 18 in multiple ways.

Figure 8g6 is an explanatory diagram showing the state of propagation and reflection of longitudinal waves within the sample 21, in which the longitudinal waves are reflected on the upper and lower surfaces of the sample 21, producing multiple echo signals WE as shown in Figure 7. . However, in FIG. 7, the horizontal axis t is time, the vertical axis, and ■ is the reflected signal intensity. Time interval method Δt of multiple echo signal Wl
If the thickness d of the sample 21 is known, the velocity V/ of the longitudinal wave propagating within the sample 21 can be calculated from the following equation.

In addition, in FIG. 7, a large amplitude reflected echo signal W
L is a signal that is repeatedly reflected within the acoustic lens 18, and the repeated state of the echo signal WL within the acoustic lens 1B is shown in FIG. Such a repeatedly reflected echo signal WL within the lens 1B comes out strongly.

Further, the following equation holds true for the general sample 21.

=0 ・・・・・・・・・(3) However, Vt is the speed of the transverse wave propagating within the sample 21.

By substituting the sound velocity VR of one wave and the sound velocity V/ of the longitudinal wave found in equation (2) into equation (3), sample 21
The sound velocity Vt of the transverse wave propagating inside the plane is staggering.

Through the above measurements and calculations, the velocities VB, Vt, and Vt of Rayleigh waves, longitudinal waves, and transverse waves are calculated, so if the sample 21 is a general sample, the elastic constant can be expressed by the following relational expression.

However, ρ is the density of the sample, μ and λ are Ramé constants, E is Young's modulus, B is bulk modulus, and is Poisson's ratio, C,...
C12 and C44 indicate tensor components.

By the way, the time interval Δt shown in FIG. 7 may be observed on the cathode ray tube screen, but it can also be measured automatically.

When measuring the time interval Δt of multiple echo signals of longitudinal waves within the sample 21, the repeatedly reflected echo signal WL within the acoustic lens 18 becomes a hindrance. A special application has already been filed in 1973 as a means to remove
A device such as that described in No. 7-102400 has been proposed. The configuration of this device is as shown in FIG. 9, and in addition to the acoustic lens 18, another dummy acoustic lens 18A is prepared, and no sample is placed on the bottom surface of this lens 18A. Water 24 is interposed between the sample stage and the piezoelectric transducer 27A to obtain a reflected signal. The multiple echo signal output obtained through the dummy acoustic lens 18A and the multiple echo signal output obtained by the sample detection acoustic lens 18 are configured to be differentially amplified. Since the reflected echo signal obtained by this device is a signal in which the repeated reflected echo signal WL generated within the lens is canceled, the elastic constant is calculated using the multiple echo signal W/ and -Z curve obtained from the device inside the sample. FIG. 2 is a block diagram showing a circuit configuration for calculating and displaying the echo signal from the multiple echo measuring device 43, which inputs the echo signal to a digital memory 44 and converts it into a digital value, and further calculates its peak and value in an arithmetic circuit 45. Detect the peak time interval Δt and use this interval Δt to calculate the equation (2). By moving it in the direction, V as shown in Fig.
-2 curves are obtained and stored in the digital memory 4T.

The obtained ■-Z curve is converted into a digital value in the digital memory 47, and then the arithmetic circuit 48 detects the interval between the peaks of the 7-2 curve and calculates lgNl. Further, using this interval IAZNI, the arithmetic circuit 49 α)
The velocity VR of the Rayleigh wave propagating within the sample 21 is calculated using the formula. After that, it is further passed through the arithmetic circuit 50 (4)
Calculate the formula, determine the elastic constant, and display the elastic constant display device 51.
Display at. The elastic constant display device 51 may be a screen display device using a cathode ray tube, or may be a recording device such as a printer.

Furthermore, the values of the velocity Vn of the Rayleigh wave and the velocity V/ of the longitudinal wave propagating in the sample 21 are respectively input to the calculation circuit 49, and (3
) and calculate the velocity V of the transverse wave propagating within the sample 21.
t, the obtained Vt value is led to the arithmetic circuit 50 (4
) is calculated, and the obtained elastic constant is displayed on the elastic constant display device 51.

FIG. 11 is a diagram showing another embodiment of the means for detecting the multiple echo signal Wt from the sample, in which a piezoelectric transducer 52 mounted on the lower surface of the lens is used, which is different from the piezoelectric transducer 27 conventionally used on the lower surface of the acoustic lens 18. Attach one or more.

The reflected signal from the sample 21 is transmitted from the piezoelectric 1 to the transducer 27
The piezoelectric transducer 52 attached to the lower surface of the lens receives multiple echo signals Wp and W6 from the front and back surfaces of the sample 21. Multiple echo signal W of the sample 21 obtained from the piezoelectric transducer 52 mounted on the lower surface of the lens
7 (echo signal % from the front surface of the sample and echo signal % from the back surface of the sample) are as shown in FIG. From FIG. 12, the time interval △t between the echo signals Wt1 and Wt
By measuring , the velocity Vz of the longitudinal wave propagating within the sample 21 can be determined.

In addition, multiple echoes of longitudinal waves within the sample 21 'Pj' W
The ninth method provides a means for making it easier to measure the time interval Δt of l.
In addition to the lucky method, a method as shown in FIG. 13 can be adopted. That is, as shown in FIG. 13, by increasing the vertical length I of the acoustic lens 18, the time interval of the repeatedly reflected echo signals WL within the acoustic lens 18 can be increased. Therefore, by increasing the lens length, the echoing M Wl from the front and back surfaces of the sample 21 and the repeatedly reflected echo signal WL within the acoustic lens 18 are
You can make it less likely that it will happen. As a result, it becomes possible to accurately and reliably measure Δt for determining the velocity Vt of the longitudinal wave propagating within the sample 21. In this case, the length of the acoustic lens 18 is adjusted so that the reflected echo signals W/ from the front and back surfaces of the sample 21 and the repeatedly reflected echo signals WL within the acoustic lens 18 do not overlap and make it impossible to measure Δt. must be set so that the echo signal Wt and the echo signal WL do not coincide in time.

FIG. 14 is a perspective view showing the overall appearance of the ultrasonic microscope device according to the present invention, and numerals 53 and 54 indicate ■-Z, respectively.
A curve display monitor and a multiple echo waveform display monitor are shown. ■-Z curve display monitor 53 is connected to ■-Z curve measuring device 4
The ■-Z curve of sample 21 obtained in step 6 is displayed as shown in FIG. 5, and the multiple echo waveform display monitor 54 is
The waveform of the reflected echo signal intensity from the sample 21 as shown in the figure or FIG. 12 is displayed. Furthermore, the elastic constants of the sample 21 obtained by various calculations are displayed on the television monitor 3T. In this case, the elastic constant is displayed using a character generator (not shown). Or,
In addition to the television monitor 37, an elastic constant display monitor 51 as described in FIG. 10 may be separately installed in or around the main body of the ultrasound microscope to display the elastic constant of the sample 21.

It should be noted that the sample measured by the apparatus of the present invention does not necessarily have to be homogeneous or isotropic, and may be any general sample, and the thickness d of the sample 21 can be determined in advance using a measuring means such as a caliper or a micrometer. Either the sample is measured or the thickness d is known, and the sample is directly input to the input means (not shown) of the microscope device for use in calculations.

〔Effect of the invention〕

As described above, according to the present invention, the Rayleigh wave velocity of the sample is determined by V-Z curve measurement, the longitudinal wave velocity of the sample is determined from the time interval of multiple echo signals, and the transverse wave velocity of the sample is determined by calculation. In addition, the elastic constant of the sample is calculated and displayed using the speed value of the knife, so not only the ultrasonic image of the sample but also the material properties of the sample can be measured and displayed automatically in a short time. An ultrasonic microscope device can be realized.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing a schematic groove configuration of an ultrasonic microscope, Fig. 2 is a side view showing the configuration of an ultrasonic microscope applied to the present invention, and Fig. 3 is an acoustic lens and holding stand shown in Fig. 2. 4 is a block diagram showing the electrical circuit of the ultrasonic microscope, 5 is an explanatory diagram showing the v-2 curve, peaks of reflected wave intensity, and peak intervals, and 6 is a front view showing the vicinity enlarged. An explanatory diagram showing the state of propagation and reflection of longitudinal waves within the sample. Fig. 7 is an explanatory diagram showing multiple echo signals due to the sample and acoustic lens over time. Fig. 8 is an explanatory diagram showing the reflected echo signal within the acoustic lens. 9 is a configuration diagram showing an example of a means for extracting multiple echo signal output from a sample. FIG. 10 is an explanatory diagram showing the velocities of each wave, longitudinal wave, and transverse wave. 11 is a block diagram showing a circuit configuration for extracting multiple echo signal output from a sample, and FIG. 12 is a block diagram showing another embodiment of a means for extracting multiple echo signal output from a sample. FIG. FIG. 13 is an explanatory diagram showing a method for making it easier to extract the multiple echo signal output from a sample, and FIG. FIG. 2 is a perspective view showing the overall appearance. 11... Eyepiece lens 12... Lens barrel 13... Objective lens 14... Goniometer 15... Holding stand 1
6...Mirror leg 17...Holding table moving device! 1B...acoustic lens-1
9... Light source for epi-illumination 20... Humidifier 21...
Sample 22... Holding table moving device scanning knob 23.
...Arm 24...Water 25...High frequency pulse generator 26.-
・Circulator 27...Piezoelectric transducer 28...Gate circuit 29...High frequency amplification circuit 30
... Mixing circuit 31 ... Local oscillator 32 ... Intermediate frequency amplification circuit 33 ... Detection circuit 34 ... Blanking circuit 35 ... Peak detection circuit 36 ... Scan converter 3T ... Television John monitor 38...
-X deflection signal generation circuit 39...X deflection signal generation circuit 40...Control circuit 41...X-Y scanning mechanism 42...Z-axis scanning mechanism 4
3...Multiple echo measuring device 44.47...Digital memory 45.4B, 49.50...Arithmetic circuit 46...V-
Z curve measurement device 51...Elastic constant display device 53...■-Z curve display monitor 54...Multiple echo waveform display monitor Fig. 5 Fig. 8 Fig. 6 Fig. 7 Fig. Otsu 1 Fig. 9

Claims (1)

[Claims] (1) Ultrasonic waves can be focused using an acoustic lens, the focused ultrasound beam can be scanned and irradiated onto a sample, and the reflected waves from the sample can be received and displayed as an ultrasound image. In an ultrasonic microscope, the relationship between the moving distance and the reflected wave intensity is measured while the sample is moved in the axial direction of the acoustic lens, and the peak of the reflected wave intensity is measured. means for determining the speed of a Rayleigh wave propagating within the sample from the distance interval of the beams; and means for determining the speed of the longitudinal wave propagating within the sample from the peak of the intensity of multiple echo waves from the sample and the time interval between the peaks. means for determining the velocity of a transverse wave propagating within the sample by calculating using the velocity of the Rayleigh wave and the velocity of the longitudinal wave; A gamma printer is equipped with a means for calculating an elastic constant, and is configured to display or record the obtained elastic constant.
Q) The means for measuring the speed of the Rayleigh waves includes a device that measures the relationship between the moving distance of the sample in the axial direction of the acoustic lens and the reflected wave intensity; a digital memory that converts the measured reflected wave intensity into a digital value and stores it;
A first arithmetic circuit that detects the peak of the reflected wave intensity and the distance interval between the peaks using this digital value, and a Rayleigh wave J0 based on the distance interval measured by this circuit.
1) The ultrasonic microscope apparatus according to claim 1, further comprising: 1) a second arithmetic circuit for calculating speed. (3) The means for increasing the velocity of the longitudinal waves includes a device that measures the intensity of multiple echo waves from the front and back surfaces of the sample over time, and a digital value of the intensity of the multiple echo waves measured by this device. digital memory that converts into memory,
The ultrasonic microscope apparatus according to claim 1, further comprising an arithmetic circuit that calculates the velocity of the longitudinal wave based on this digital value.