JPH08145967A - Ultrasonic measuring apparatus - Google Patents

Abstract

PURPOSE: To obtain the complex information of a reflection signal from an ultrasonic sample in a wide frequency range by providing different cut-off frequencies, and switching a plurality of low-pass filters in which a signal multiplied by multiplying means is selectively input by the frequency. CONSTITUTION: A computer 1 selects a low-pass filter having a set frequency used for measurement and frequency characteristics conforming to a burst width from a plurality of low-pass filters 15a-1, 15a-2,..., 15b-2,.... Then, the computer 1 so switches input switching switches 14a, 14b and output switching switches 16a, 16b as to pass a reception signal through the selected filter. Since the width of the burst wave is decided according to the oscillating frequency of an oscillator 2, the computer 1 so switches the switches 14a, 14b and 16a, 16b as to connect the filters 15a-2, 15b-2 to multipliers 12a, 12b, A-C converters 17a, 17b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic measuring device for measuring elastic properties of a minute portion of a sample by using ultrasonic waves.

[0002]

2. Description of the Related Art An ultrasonic wave converged through an acoustic lens is incident on a sample and a necessary reflected wave component is extracted from the sample reflected wave to create an ultrasonic image, or V (Z) of the sample.
An ultrasonic microscope is known as a device that measures a curve to detect elastic properties of a minute portion of a sample.

Although the above-mentioned ultrasonic microscope measures only the intensity of the reflected wave from the sample, the ultrasonic wave for detecting the intensity and phase of the reflected wave in order to obtain more information about the elastic property of the sample. Measuring devices are being considered. An ultrasonic measuring device of this kind is disclosed in JP-A-5-26854.

FIG. 5 is a diagram showing an example of the configuration of an ultrasonic measuring device for detecting the intensity and phase of a sample reflected wave. In this ultrasonic measuring device, the reference signal oscillator 101 always outputs a continuous wave of a constant frequency, and the control unit 103, to which the transmission trigger is input from the computer 102, synchronizes with the transmission trigger to change the frequency of the reference signal oscillator 101. An ON / OFF signal corresponding to a time width of several tens of cycles is sent to the analog switch 104.
Output to.

The analog switch 104 is switched according to ON / OFF of the signal from the control unit 103, and when ON, the signal generated by the reference signal oscillator 101 is output to the circulator 105 to generate a transmission burst signal. This transmission burst signal passes through the circulator 105 and is applied to the transducer 106. The transmission burst wave is electroacoustic converted by the transducer 106 and converted into ultrasonic waves. This ultrasonic wave propagates through the acoustic lens 107 and is incident on the sample 109 placed on the sample stage 108. A space between the acoustic lens 107 and the sample 109 is filled with a coupler liquid 110 for propagating ultrasonic waves.

The reflected ultrasonic wave reflected by the sample 109 propagates again through the coupler liquid 110 and the acoustic lens 107, and is converted into an electric signal by the transducer 106. Hereinafter, this signal is referred to as a received signal. Received signal is circulator 1
It is amplified by the preamplifier 111 through 05 and input to the two multiplication units 112a and 112b.

On the other hand, the multiplication section 112a multiplies the continuous wave output from the reference signal oscillator 101 by the received signal to detect the in-phase component. The other multiplication unit 112b
Then, the continuous wave output from the reference signal oscillator 101
The signal having the 90 ° phase change in 13 is multiplied by the received signal to detect the quadrature phase component.

Here, the signal output from the reference signal oscillator 101 is defined as sin (ωt). Note that ω is frequency and t is time. Since the phase of the received signal is delayed with respect to the transmission due to the elastic properties of the sample, the time of propagation in the acoustic lens and the coupler liquid, and so on, if this phase delay is φ, then Bsi
It can be written as n (ωt−φ). Note that B is the strength of the received signal.

Therefore, the in-phase output u ₁ of the multiplication unit 112a and the quadrature phase output u ₂ of the multiplication unit 112b are as follows. u ₁ (t) = (B / 2) {cosφ-cosφcos (2ωt) -sinφsin (2ωt)} (1) u ₂ (t) = (B / 2) {sinφ + sinφcos (2ωt) -cosφsin (2ωt)} ( 2) Since φ is a constant, sin φ and cos φ are also constants. Therefore, u ₁ and u ₂ have a DC component and a frequency component of 2ω.
in, cos can be taken out.

The 2ω component of the in-phase output of the multiplication unit 112a and the quadrature phase output of the multiplication unit 112b are removed by the low-pass filters 114a and 114b, respectively, and only the DC components corresponding to sin φ and cos φ remain. The A / D converters 115a and 115b convert the detection outputs of the in-phase and quadrature phases into A / D
D conversion is performed, the phase detection output of the sample reflection is converted into a digital signal, and the digital signal is stored in the memory in the computer 102. In the computer 102, sin φ, c of the sample reflection stored
The phase and the reflection intensity are calculated from the osφ component. The Z scanning unit 116 changes the distance between the acoustic lens and the sample according to a command from the computer 102, and adjusts focusing and the like.

[0011]

However, the above-mentioned conventional ultrasonic measuring device has the following drawbacks.
That is, generally, the resolution of the ultrasonic measurement device increases in proportion to the reciprocal of the used frequency, and the absorption coefficient of the ultrasonic wave increases in proportion to the square of the used frequency. Therefore, it is necessary to select the frequency according to the purpose of use. For example, a high frequency is selected when measuring with high resolution, and a low frequency is selected when measuring the inside of a sample. In addition, it is required that the frequency be variable when measuring the characteristics of waves such as Lamb wave and Sezawa wave that exhibit frequency dispersion in the speed of sound.

In the measuring device disclosed in Japanese Unexamined Patent Publication No. 5-26854, it is necessary to be able to remove a frequency twice the oscillation frequency used as a low pass filter. The cutoff frequency determines the lowest frequency that can be used by the measuring device. For example, if the device can be used up to 100MHz, the cutoff frequency of the low-pass filter should be 200MHz or less.
If the device can be used up to 0MHz, the cutoff frequency is 60MH
must be less than or equal to z.

On the other hand, since the absorption of ultrasonic waves increases as the frequency increases, the focal length of the acoustic lens decreases at high frequencies. When the focal length becomes shorter, it is necessary to shorten the width of the burst wave so that the reflection inside the acoustic lens does not interfere with the reflection signal from the sample. For example, at 1 GHz, the width of the burst wave is about 50 nsec. The output from the multiplication unit at this frequency is a rectangular wave with a width of 50 nsec and a 2 GHz signal, and only the 2 GHz signal must be removed by a low pass filter. Generally, the frequency required to pass a square wave with a width of t [sec] is DC to 3 * 1 / t, so 5
In order to pass the rectangular wave of 0 nsec, the cutoff frequency of the low pass filter must be 60 MHz or higher. Also, if the cutoff frequency of the lowpass filter is selected low, the S / N ratio will be good, so it is desirable to select a lowpass filter having the cutoff frequency as low as possible.

Therefore, there is a drawback that a low-pass filter having a constant cutoff frequency cannot perform phase detection in a wide frequency range. The present invention has been made in view of the above circumstances, and can perform phase sensitive detection at a wide frequency by switching many kinds of low-pass filters having different cutoff frequencies depending on the frequency, and the intensity and phase of the reflected wave of the sample. It is an object of the present invention to provide an ultrasonic measuring device capable of detecting

[0015]

The present invention has taken the following means in order to achieve the above object. According to the present invention, which corresponds to claim 1, a burst wave oscillating means that generates a high frequency burst wave and has a variable frequency, and the generated burst wave is converted into an ultrasonic wave, converges into a minute spot, and is made incident on the sample. The ultrasonic wave transmitting / receiving means for converting the reflected wave of the above into an electric signal again, the phase shifting means for changing the phase of the reference signal of the same frequency as the burst wave, and the signal output from this phase shifting means and the reference signal respectively. Multiplication means for multiplying the electric signal output from the ultrasonic wave transmission / reception means as a wave, and a plurality of low-pass filters having cut-off frequencies different from each other and to which the signals multiplied by the multiplication means are selectively input, Switching means for switching a low-pass filter for inputting the signal multiplied by the multiplying means, means for storing the signal passed through the low-pass filter, and ultrasonic wave The morphism direction and Z-axis, and configured to and a means for changing the relative distance of the ultrasonic wave transmitting and receiving means and the sample in the Z-axis direction.

According to a second aspect of the present invention, at least one oscillating means having a variable frequency for generating a high frequency continuous wave by the burst wave oscillating means, and the continuous wave generated by the oscillating means are cut off to generate a burst wave. And a continuous wave output from the oscillating means is used as the reference signal. The present invention corresponding to claim 3 is characterized in that the switching means comprises a semiconductor switch.

[0017]

The present invention has the following effects by taking the above measures. According to the present invention corresponding to claim 1, a high frequency burst wave is generated from the burst wave oscillating means and adjusted to an arbitrary frequency. The burst wave generated by the burst wave oscillating means is converted into ultrasonic waves by the ultrasonic wave transmitting / receiving means, converges to a minute spot and is incident on the sample. The reflected wave from the sample is received by the ultrasonic wave transmitting / receiving means, converted into an electric signal again, and input to the multiplying means. On the other hand, the signal generated by changing the phase of the reference signal having the same frequency as the burst wave in the phase shift means and the reference signal are input to the multiplication means as reference waves and multiplied by the received signal. The plurality of low-pass filters are switched by the switching means to low-pass filters having an appropriate cutoff frequency. Then, the multiplied signal is input to the already-switched low-pass filter to remove the high frequency component. The signal passed through the low pass filter is stored in the storage means. Then, the incident direction of the ultrasonic wave is set to the Z axis, and the relative distance between the ultrasonic wave transmitting / receiving means and the sample is changed in the Z axis direction for measurement.

According to the present invention corresponding to claim 2, a high frequency continuous wave is generated from at least one oscillating means included in the burst wave oscillating means, and the oscillated continuous wave is cut out by the burst wave converting means. Are converted to burst waves.

According to the present invention corresponding to claim 3, since the low-pass filter switching means is a semiconductor switch, high-speed switching is realized, and two measurements can be performed within a time required for one measurement operation. it can.

[0020]

Embodiments of the present invention will be described below. FIG. 1 shows the configuration of an ultrasonic measurement apparatus according to the first embodiment of the present invention. In the ultrasonic measurement apparatus of this embodiment, the oscillator 2 generates a continuous wave having a frequency designated by the computer 1, and a part of the continuous wave generated by the oscillator 2 is converted into a semiconductor according to the gate width of the burst gate signal. Switch 3 turns off. The transmission burst signal cut out by the semiconductor switch 3 is converted into ultrasonic waves by the transducer 4. The transducer 4 is attached to one end surface of the acoustic lens 5. The acoustic lens 5 transmits the ultrasonic waves converted by the transducer 4 from the concave surface formed on the other end surface and converges the ultrasonic waves on a minute spot. Sample 6 near the focal point of acoustic lens 5
Are placed in a water tank 8 on the sample table 7. The aquarium 8 is filled with coupler liquid 9 for the propagation of ultrasonic waves. The transmission burst signal is input to the transducer 4 via the semiconductor switch 10 for switching between transmission and reception. Further, the reception signal of the sample reflected wave received by the acoustic lens 5 is output to the preamplifier 11 via the semiconductor switch 10. That is, the semiconductor switch 10 switches the input / output of the transducer 4 between the oscillator 2 and the preamplifier 11 based on the transmission / reception switching signal.

The preamplifier 11 has two multiplication units 12a,
12b is connected. One of the two continuous waves output from the oscillator 2 is input to the multiplier 12a as a first reference signal. The other multiplication unit 12b outputs another signal obtained by dividing the continuous wave output from the oscillating unit 2 into two, for example, a signal having a 90 ° phase delay after passing through a 90 ° phase shift unit 13 configured by a 90 ° hybrid. It is input as the second reference signal.

Inputs to the output terminals of the multipliers 12a and 12b are switched by input switching switches 14a and 14b, respectively, and low-pass filters 15a-1, 15a-2, 15a-3, ... And 15b having different frequency characteristics.
, 1, 15b-2, 15b-3, ... Are connected in parallel.

The output terminals of the low-pass filters 15a and 15b are connected to the A / D converters 17a and 17b through the output switching switches 16a and 16b which are interlocked with the input switching switches 14a and 14b, respectively. A / D
The conversion outputs of the conversion units 17a and 17b are input to the computer 1.

The computer 1 is connected to a control unit 18 for controlling the overall timing, a Z scanning unit 19 for changing the distance between the sample 6 and the acoustic lens 4 in the Z direction, and a Z distance measuring unit 20 for measuring the moving distance. ing.

Next, the operation of the present embodiment configured as described above will be described. FIG. 2 is a time chart showing the operation timing of this embodiment. First, computer 1
To the frequency used for measurement. When the frequency used for measurement is set, the computer 1 has a plurality of low-pass filters 15a-1, 15a-2, 15a-3 having a frequency characteristic that matches the set frequency and the burst width. …, 15b-1,
15b-2, 15b-3 ... Are selected. Next, the computer 1 switches the input selector switches 14a and 14b so that the received signal passes through the selected low pass filter.
And the output switching 16a and 16b are switched.

The width of the burst wave is substantially determined by the oscillation frequency of the oscillator 2, and specifically, it is 500 to 100 MHz.
1000nsec, 200-500nsec at 200MHz, 4
100-200nsec at 00MHz, 50 at 800MHz
Approximately 100 nsec or so, it becomes approximately 50 nsec at 1 GHz. For example, assume that a frequency of 400 MHz is set in the oscillator 2 and the burst width thereof is 150 nsec. The range of the cutoff frequency required at this time is between 20 MHz and 800 MHz, whichever has the lowest frequency characteristic. The cutoff frequency of the low-pass filters 15a-1 and 15b-1 is 5 MH
z, the cutoff frequency of the low pass filters 15a-2 and 15b-2 is 30 MHz, and the low pass filters 15a-3 and 15
Assuming that the cut-off frequency of b-3 is 100 MHz, the computer 1 causes the input switching switches 14a and 14b to include the multiplication units 12a and 12b and the low-pass filters 15a-2 and 15b.
-Switch to connect 2 and output switch 1
6a and 16b are low-pass filters 15a-2 and 15b-
2 and the A / D conversion units 17a and 17b are switched to be connected.

As shown in FIG. 2A, the oscillator 2 constantly outputs a continuous wave at the frequency set by the computer 1. The transmission trigger shown in FIG. 2B is the computer 1
Is given to the control unit 18 from the control unit 18, in synchronization with a transmission trigger from the control unit 18, ON and O of a time width of several tens of cycles of the frequency of the oscillator 2 shown in FIG. 2C (150 nsec in this case).
The FF signal is applied to the analog switch 3. Further, as shown in FIG. 2D, a switching signal that turns on earlier and turns off later than the signal in FIG. 2B is output to the analog switch 10. The analog switch 3 is switched according to ON and OFF of the signal, and when it is ON, the oscillator 2
The signal generated by is output to the analog switch 10.
In this way, the transmission burst signal shown in FIG. The analog switch 10 is switched to the side of the analog switch 3 when the signal of FIG. 2D is on, and switched to the side of the preamplifier 11 when it is off.

When the signals shown in FIGS. 2C and 2D are both ON,
The transmission burst signal is applied to the transducer 4 through the analog switch 10. The transmitted burst wave is electroacoustic converted by the transducer 4 and converted into ultrasonic waves. This ultrasonic wave propagates through the acoustic lens 5, passes through the coupler liquid 9, is converged, and enters the sample 6.

The ultrasonic wave incident on the sample 6 is reflected by the sample 6, propagates through the coupler liquid 9 and the acoustic lens 5 again, and is converted into an electric signal (received signal) by the transducer 4.
The received signal passes through the analog switch 10 that has already been switched to the preamplifier 11 side, is amplified by the preamplifier 11, and is input to the multiplication units 12a and 12b.

The multiplication unit 12a multiplies the received signal by the continuous wave output from the oscillator 2 as a reference signal, and outputs the result as an in-phase component. On the other hand, in the multiplication unit 12b, the received signal is multiplied by the second reference signal output from the oscillator 2 and delayed in phase by 90 ° in the phase shift unit 13,
The result is output as the quadrature phase component.

The outputs of the multiplying unit 12a and the multiplying unit 12b are low-pass filters 15a-2 and 15b-2 selected by the changeover switches 13a and 13b, respectively. The component is removed and a square wave with a size corresponding to cosφ and sinφ remains. Note that ω is the frequency transmitted by the oscillator 2, and φ is the phase delay of the received signal.

FIG. 2 (f) is a received signal before detection, and FIG.
(G) is the detection output of the low-pass filter 15a-2, FIG.
(H) shows the output of the low-pass filter 15b-2. The actual received signal is shown in Fig. 2 (f) before detection.
In addition to sample reflection, transmission leakage, lens first reflection, lens second reflection, etc. are included, so the phase detection output is as shown in FIG.
As in (g) and (h), a rectangular wave corresponding to each reflection is obtained.

Low-pass filters 15a-2, 15b-2
The signals that have passed through are changeover switches 16a and 16 respectively.
It is input to the A / D conversion units 17a and 17b through b. A
The / D converters 17a and 17b take out only the necessary sample reflection from the plurality of signal components. For this purpose, FIG.
The control unit 18 generates an A / D conversion trigger signal at a timing delayed by Td with respect to the transmission trigger as shown in (i), and A
It is given to the / D converters 17a and 17b as a trigger signal.
Each detection output is A / D converted, and the phase detection output of the sample reflection is converted into a digital signal and stored in the memory in the computer 1. The time delay amount Td of the transmission and A / D conversion trigger signal can be set from the computer 1 to the control unit 18.

The Z scanning section 19 changes the distance between the acoustic lens and the sample 6 in response to a command from the computer 1 to adjust focusing and the like. When performing V (z) measurement, the generation timing Td of the A / D conversion trigger signal is adjusted to the sample reflection position while observing the signal waveform shown in FIG. Next, the Z scanning unit 19 changes the distance between the acoustic lens 5 and the sample 6 and repeats the above process while measuring the amount of movement by the Z distance measuring unit 20 to obtain the complex information cos φ of the sample reflection,
The sin φ is loaded into the computer 1 together with the amount of movement in the Z direction. The timing of A / D conversion is changed according to the change in the distance between the acoustic lens 5 and the sample 6. Specifically, if the amount of movement in the Z direction from the measurement start position is Δz, the timing shift is ΔTd, and the sound velocity of the coupler is v, the computer 1 calculates the A / D conversion timing from the following equation. And change the timing.

ΔTd = 2Δz / v (3) Further, when the oscillation frequency set in the oscillator 2 is 100 MHz and the burst width is 1000 nsec, the required cutoff frequency range is between 3 MHz and 200 MHz, and the frequency characteristic is preferably set. The lower one. In this case,
The computer 1 has input switches 14a and 14b.
To the multiplication units 12a and 12b and the low-pass filter 15a-
1, 15b-1 are connected to each other, and the output switching switches 16a and 16b are connected to the low-pass filter 15a-.
1, 15b-1 and A / D converters 17a and 17b are switched so as to be connected to each other. When the oscillation frequency set for the oscillator 2 is 1 GHz and the burst width is 50 nsec, the required cutoff frequency range is 60 MHz to 2 GH.
The frequency characteristic is as low as possible between z. In such a case, the computer 1 switches the input switching switches 14a and 14b so that the multiplication units 12a and 12b and the low-pass filters 15a-3 and 15b-3 are connected, and the output switching switches 16a and 16b are switched to the low-pass filter 15a. -3, 15b-3 and the A / D converter 17a,
Switch to connect 17b. After that, incidence of ultrasonic waves and extraction of sample reflected waves are repeated to form an ultrasonic image or measure a V (z) curve.

As described above, according to this embodiment, the multiplication unit 14
Since a plurality of low-pass filters having different frequency characteristics are provided at the subsequent stage of a and 14b and the output switching switches 16a and 16b are provided at the output stages of the low-pass filters, the low-pass filters are switched according to the oscillation frequency of the oscillator 2. The complex information contained in the sample reflection can be measured over a wide range of frequencies.

Next, a second embodiment of the present invention will be described. FIG. 3 is a diagram showing a configuration of a main part of the ultrasonic measurement device according to the second embodiment. In this embodiment, in the ultrasonic measuring device shown in FIG. 1, the multiplication units 12a and 12b are connected to the A / D conversion unit 1.
This is an example in which the configuration between 7a and 17b is replaced with the configuration shown in FIG.

In this embodiment, the changeover switches 14a and 16a for switching the input and output of the low pass filters 15a-1, 15a-2, 15a-3, ... Of the first embodiment are semiconductor switches 301a-1, 301a-2, 302a. −
1, 302a-2, and a low-pass filter 15b-
Semiconductor switches 301b-1, 301b-2, 302b-1, 302b are provided as changeover switches 14b, 16b for switching the input / output of 1, 15b-2, 15b-3.
-2.

100 commonly used in acoustic microscopy
The semiconductor switch that switches the frequency above MHz is SPDT
It has 1 input and 2 outputs. Therefore, when switching three low-pass filters as in the present embodiment, it is necessary to configure the semiconductor switches in a two-stage stack as shown in FIG.

Next, the operation of this embodiment will be described. Like the first embodiment, for example, the low-pass filter 15a-1,
The cutoff frequency of 15b-1 is 5 MHz, the cutoff frequencies of the lowpass filters 15a-2 and 15b-2 are 30 MHz, and the cutoff frequencies of the lowpass filters 15a-3 and 15b-3 are 100 MHz.

When the oscillation frequency is 100 MHz and the burst width is 1000 nsec, the computer 1 sets the frequency 100 MHz in the oscillator 2. Further, the computer 1 has low-pass filters 15a-1 and 15b-1.
So that the signals of the multipliers 13a, 13b are input to the semiconductor switches 301a-1, 301a-2, 301b-.
1, 301b-2 are switched, and the low-pass filter 15a
-1, 15b-1 outputs are A / D converters 17a, 17b
Input to the semiconductor switches 302a-1, 302
Switch a-2, 302b-1, 302b-2. The subsequent operation is the same as in the first embodiment. If the measurement is performed under such a setting, the complex information of the ultrasonic sample reflection at the frequency of 100 MHz can be obtained.

Burst width 150 ns at frequency 400 MHz
When measuring with ec, the frequency of 400 MHz is set from the computer 1 to the oscillator 2. Also, the computer 1 includes a multiplier 13 in the low-pass filters 15a-2 and 15b-2.
Semiconductor switch 3 so that signals a and 13b are input
01a-1, 301a-2, 301b-1, 301b-
2 is switched, and the low-pass filters 15a-2 and 15b-
The semiconductor switches 302a-1, 302a-2, 302 are arranged so that the output of 2 is input to the A / D converters 17a, 17b.
b-1 and 302b-2 are switched. This gives 400
Complex information of the ultrasonic sample reflection at the frequency of MHz is obtained.

The above operation is repeated by alternately switching the frequency while changing the relative distance between the acoustic lens 5 and the sample 6 in the Z direction by the Z scanning unit 19. It takes only a few [nsec] to switch a semiconductor switch, which is extremely fast compared to several tens [msec] of a mechanical switch.
Complex V of two frequencies in one V (z) measurement operation
(Z) The curve can be measured.

As described above, according to the present embodiment, since a plurality of low-pass filters having different frequency characteristics are switched by the semiconductor switch, the frequency switching becomes fast and a plurality of V (z) measurements can be made at one time. A V (z) curve of frequency is obtained.

Although this embodiment has described the case of three low-pass filters, the present invention is not limited to this. Any number of semiconductor switches and phase shifters may be added depending on the frequency band to be measured.

Although there is a case where the frequency switching is not fast depending on the oscillating unit, in such a case, it may be considered that a plurality of oscillating units having different oscillating frequencies are switched by the semiconductor switch.

The present invention is not limited to the above embodiments. In each of the embodiments, the phase detection is performed by using the oscillator signal and the signal obtained by changing the phase thereof as the reference signals. However, as described in JP-A-5-26854, the reference signals having different phase changes are used. It is also possible to detect the phase using three or more signals.

Further, the phase and intensity of the reflected wave are calculated from the phase detection output. The reflected intensity is detected by peak detection,
It is also possible to detect only the phase from the phase detection output. Furthermore, the intensity and phase of the two-dimensional reflected wave can be measured by repeating the measurement while the two-dimensional scanning is performed with the XY scanning unit.

[0049]

As described in detail above, according to the present invention, the complex information of the reflected signal from the ultrasonic sample in a very wide frequency range can be obtained by switching the low pass filter of the phase detector according to the frequency. To be obtained.

According to the present invention, by switching the low-pass filter by a high-speed semiconductor switch, one V (z)
Complex V (z) curves of a plurality of frequencies can be obtained in the time required for measurement, and a complex ultrasonic image at a plurality of frequencies can be acquired by one two-dimensional XY scan. Furthermore, since the cutoff frequency can be selected as low as possible within the required range, a highly accurate complex V with a good S / N ratio can be selected.
(Z) It becomes possible to perform measurement.

[Brief description of drawings]

FIG. 1 is a functional block diagram of an ultrasonic microscope according to a first embodiment of the present invention.

FIG. 2 is a timing waveform chart for explaining the operation of the ultrasonic microscope according to the first embodiment.

FIG. 3 is a functional block diagram of essential parts of an ultrasonic microscope according to a second embodiment of the present invention.

FIG. 4 is a functional block diagram of a main part of a conventional ultrasonic measurement device.

[Explanation of symbols]

1 ... Computer, 2 ... Oscillator, 3 ... Semiconductor switch,
5 ... Acoustic lens, 6 ... Sample, 10 ... Semiconductor switch, 1
2a, 12b ... Multipliers 12a, 12b, 13 ... Phase shifter,
14a, 14b ... Input changeover switch, 15 ... Low pass filter, 16 ... Output changeover switch, 18 ... Control section.

Claims (3)

[Claims] 1. A burst wave oscillating means having a variable frequency for generating a high frequency burst wave, the generated burst wave being converted into an ultrasonic wave, converged into a minute spot and made incident on a sample, and a reflected wave from the sample is again generated. An ultrasonic wave transmitting / receiving means for converting into an electric signal, a phase shifting means for changing the phase of a reference signal having the same frequency as the burst wave, and the ultrasonic wave using the signal output from the phase shifting means and the standard signal as reference waves, respectively. Multiplying means for multiplying by an electric signal output from the transmitting / receiving means, a plurality of low-pass filters having cut-off frequencies different from each other and selectively inputting signals multiplied by the multiplying means, and multiplying by the multiplying means Switching means for switching the low-pass filter for inputting the input signal, means for storing the signal passed through the low-pass filter, and the Z-axis for the incident direction of the ultrasonic wave. The ultrasonic measuring device is provided with the ultrasonic transmitting / receiving device and a device for changing the relative distance between the sample and the sample in the Z-axis direction. 2. The burst wave oscillating means includes at least one oscillating means having a variable frequency for generating a high frequency continuous wave, and a burst wave converting means for cutting off the continuous wave generated by the oscillating means to convert into a burst wave. The ultrasonic wave measuring device according to claim 1, wherein the continuous wave output from the oscillating means is used as the reference signal. 3. The ultrasonic measurement device according to claim 1, wherein the switching means is a semiconductor switch.