JPH0280954A - Ultrasonic microscope - Google Patents

Abstract

PURPOSE:To accurately detect a reflected wave, in an ultrasonic microscope for transmitting an ultrasonic wave to an object to be measured and catching the reflected waves from the outer and inner surfaces of said object to perform acoustoelectric conversion, by taking out a reflection signal in a time series manner to display the acoustic structure of a deep part as an image. CONSTITUTION:An XY scanning part 23 is operated to perform the relative XY scanning of an acoustic lens 21 and a specimen 22 and the signal S subjected to acoustoelectric conversion through the acoustic lens 21 and a piezoelectric transducer 20 is guided to parallel peak detectors 40a, 40b. The reflection signals amplified by amplifiers 41a, 41b are alternately gated to be supplied to amplifiers 43a, 43b. The output signals of the amplifiers 43a, 43b are reset by reset means 45a, 45b upon the reception of reset pulse signals Ra, Rb and respectively amplified by amplifiers 46a, 46b and a switch 47 is changed over by a signal change-over signal SS to selectively send the output signals to an amplifier 48 and the signal amplified by the amplifier 48 is sent to an image memory 30. This signal is converted to an image by an image processor 50 to be displayed on a CRT monitor 51. By this method, the peak value of the reflected wave of the specimen is alternately obtained and the reflected wave can be accurately detected without omission.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention transmits ultrasonic waves to an object to be measured, captures reflected waves from the surface and inside of the object, and performs acoustic-electrical conversion. , regarding an ultrasonic microscope that extracts and displays the reflected signal, in particular, extracts the reflected signal by time separation and extracts the acoustic JI4 in the deep part of the object to be measured.
This invention relates to improvements in means for displaying structures as images.

[Conventional technology]

Fig. 5(a) is a block diagram showing an example of the configuration of a conventionally known ultrasonic flaw detection device.6 In Fig. 5(a), ■ indicates an ultrasonic probe, and 2 indicates an object to be measured. It is a sample as an object. The ultrasonic probe 1 and the sample 2 are configured to be able to scan relative to each other, and a two-dimensional XY plane scan is performed by an XY constant scan 3.

At this time, timing pulses generated in the XY constant scan 3 at equal temporal intervals in the X direction and the Y direction are input to the pulse controller 4. The pulse controller 4 creates a transmission trigger pulse based on the input pulse, and supplies it to the ultrasonic transmitter/receiver circuit 5 . When this transmission/reception circuit 5 is given a transmission trigger pulse, it generates a transmission pulse and supplies the transmission pulse to the ultrasound probe 1 . Therefore, ultrasonic waves are generated from the ultrasonic probe 1 and are incident on the sample 2 via the water 6 which is the coupler liquid. The reflected waves from the surface and inside of the sample 2 enter the ultrasonic probe 1 again, are converted back into electrical signals, and are input to the transmitter/receiver circuit 5 . A reflected signal corresponding to the reflected wave input to the transmitter/receiver circuit 5 is amplified and enters the gate 7.

The gate 7 is controlled to be <0N-OFF by a gate control pulse from the pulse controller 4 so as to extract only the necessary reflected signal. The reflected signal that has passed through the gate 7 is subjected to envelope detection by an envelope detector 8, and its amplitude is detected. The signal indicating the detected amplitude is converted into a digital signal every certain unit time by an A/D converter 9 that responds to control pulses from the pulse controller 4. In this way, information such as the intensity of reflected waves from inside the sample 2 is detected at successively different distances (depths). The information signal thus detected is input to the image memory 10 which responds to control pulses from the pulse controller 4 and is stored as digital data. This stored digital data, ie, information signals such as reflected wave intensity, is converted into a TV signal and supplied to the CRT monitor 11, where it is displayed as a B-mode image.

FIG. 5(b) is a diagram showing another configuration example in which a part of the device shown in FIG. 5(a) is modified.As shown in FIG. 0, in this example, the envelope detector 8 is replaced with A peak detector 12 is used. In addition, in order to separate and extract the reflected wave intensity corresponding to each depth position of the sample 2 using the peak detector 12,
It is necessary to sequentially reset the obtained peak values. Therefore, as shown in the figure, a reset signal is output from the pulse controller 4 to the peak detector 12.

[Problem B that the invention attempts to solve]

Among the above-mentioned conventional techniques, the one that performs envelope detection as shown in FIG. 5(a) detects the reflected wave intensity at a predetermined time point in a certain time interval (depth interval). . For this reason, as shown in FIG. 6(a), the maximum value during the time interval is not necessarily detected, and there is a drawback that the reflected wave intensity of the ultrasonic wave is not detected correctly.

In addition, in the case where peak detection is performed as shown in FIG. 5(b), peak values are detected at certain time intervals (depth intervals). Therefore, although the maximum value during that time interval is detected, as shown in FIG. 6(b), since no detection is performed at the time of reset, so-called "missing detection" occurs. For this reason, this example also has a drawback in that the reflected wave intensity of the ultrasonic wave cannot be detected correctly.

Therefore, an object of the present invention is to be able to accurately detect information such as reflected wave intensity indicating the internal structure of an object to be measured without causing any "missing detection", and to provide A-mode information, B-mode information, etc. An object of the present invention is to provide an ultrasonic microscope that can capture and display information, three-dimensional information, etc.

[Means to solve the problem]

The present invention has taken the following measures to solve the above problems and achieve the objectives. That is, an acoustic lens is used to generate a focused spherical ultrasonic wave, the reflected waves from the surface and interior of the object to be measured are captured again by the acoustic lens, acousto-electrical conversion is performed, and the reflected signals are extracted and displayed. The ultrasonic microscope is equipped with a gate that can separate and extract reflected signals within a predetermined time range and introduce them, and a detector that detects the reflected signals introduced by the gate and detects information such as the intensity of the reflected waves. a receiving circuit group comprising several receiving circuits connected in parallel; a control means for sequentially and periodically operating the receiving circuits of each system by controlling the gates of each system in the receiving circuit group; A signal extracting means for sequentially selecting and extracting information signals detected by the receiving circuits of each system which are operated periodically by the control means to form a series of signal trains; and a signal extracting means for processing the signal train extracted by the signal extracting means. and a means for displaying an image of the acoustic internal structure of the object to be measured.

[Effect]

By taking such measures, the following effects are achieved. In other words, when a receiver circuit group is used in which two receiver circuits including a peak detector and its reset circuit are connected in parallel, the receiver circuits are separated at predetermined time intervals depending on the function of the gate. The received reflected signals are sequentially and alternately input to the receiving circuits of each system.

Therefore, the reflected wave intensity (
The peak value of the information) is detected and held by a peak detector on one side. The peak value of the reflected wave intensity (information) of the second reflected signal is detected and held by the peak detector on the other side. Thereafter, peak values are detected and held alternately in the same manner. Furthermore, one III! 1 (fl!!) While the peak value is being detected and held on one side (ill), the peak value that was previously detected and held is being reset on the other side (one side). As mentioned above, the peak values are alternately detected and held, and the gI multiplication signals are alternately extracted through a signal extraction means consisting of a changeover switch, etc., to form one time-series signal sequence. This signal sequence is processed and displayed as an image.In this way, information such as the intensity of reflected ultrasonic waves, which indicates the acoustic internal structure of the object to be measured, is detected and displayed accurately and without any "missing detection". It becomes possible.

〔Example〕

FIG. 1 is a block diagram showing the configuration of a first embodiment of the present invention. In Fig. 1, the code 2 shown in the central part on the left side of the figure
0 is a piezoelectric transducer, which is coupled to an acoustic lens 21. The acoustic lens 21 and the sample 22 as the object to be measured are configured to be able to perform XY scanning relative to each other, and two-dimensional XY plane scanning is performed by the XY constant scanning 23. From the XY constant scan 23, a pulse SX corresponding to the X position in the X scan and a pulse SY corresponding to the Y position in the Y scan are sent out. The above pulse SX is applied to a synchronization circuit 25, which will be described later, and the pulse SY is applied to an image memory 30, which will be described later.

A reference tally clock generator 24 generates a reference tally clock CK as a timing pulse. This standard tarokku CK
is supplied to the synchronization circuit 25 on the one hand. The synchronization circuit 25 synchronizes the reference clock CK with the pulse SX from the XY scanning section 23, creates a transmission trigger pulse TT, and supplies it to the transmission pulse generator 26. The transmission pulse generator 26 has a frequency of, for example, 30MH2 to 10MHz.
A transmission pulse S in a relatively low frequency band of about 0 MHz is output. This transmission pulse S is applied to the piezoelectric transducer 20 through a circulator 27. The piezoelectric transducer 20 performs electro-acoustic conversion on the transmitted pulse S to generate ultrasonic waves. This generated ultrasonic wave is converted into a focused spherical wave by the acoustic lens 21, propagates through the water 6 which is the coupler liquid, and is irradiated onto the sample 22. A part of the irradiated ultrasonic waves is reflected by the surface of the sample 22, while the other part enters the inside of the sample 22.

The reflected waves reflected from the surface, the bottom surface of the sample 22, or the acoustically non-uniform portion inside the sample return to the piezoelectric transducer 20 through the acoustic lens 21 again, where they are subjected to acoustic-electrical conversion. A reflected signal corresponding to the reflected wave thus obtained is guided to the preamplifier 28 through the circulator 27. The reflected signal amplified by the preamplifier 28 is sent to a receiving circuit group, ie, a receiving circuit 40 having a two-system parallel configuration, which will be described later.
a, input to 40b.

The reference clock C generated by the reference clock generator 24
On the other hand, K is supplied to a delay circuit 29, where it is delayed and then sent to an image memory 30 as a sampling pulse SK.
Supplied as. Further, the reference tarokku CK is
Position pulse controller 31. The signal is supplied to the synchronous frequency divider circuit 32. Transmission trigger pulse TT from the synchronization circuit 25
The above XZ position pulse controller 31. The signal is supplied to the synchronous frequency divider circuit 32. The XZ position pulse controller 31 inputs an address corresponding to the X position in the image memory 30 and a Z position.
Set the start address of the position (depth position). The start position is set by the 7-position setting device 33. Further, the synchronous frequency divider circuit 32 divides the frequency of the reference tally clock by two, and uses the transmission trigger pulse T as a reset signal.
T is used to synchronize each X scanning pulse. The pulse SD frequency-divided by the synchronous frequency divider circuit 32 is sent to the gate pulse controller 34. Reset pulse controller 35.
A signal is provided to the switching pulse controller 36.

The two receiving circuits 40a and 40b having a parallel configuration have exactly the same configuration. Therefore, here, the receiving circuit 40
The configuration will be explained using example a.

The amplifier 41a amplifies the input reflected signal and sends it to the gate 4.
2 Have a input. The gate 42a is turned ON-OF by the control pulses G and G from the gate pulse controller 34.
F-controlled, and when ON, the output of the amplifier 41a is passed through and applied to the next amplifier 43a. The amplifier 43a further amplifies the input signal and supplies it to the peak detector 44a. The peak detector 44a detects the peak value of the input signal and holds that value. When the reset device 45a is turned on by the reset pulse Ra from the reset pulse controller 35, it discharges the charge stored in the capacitor of the peak detector 44a and performs a reset.The amplifier 46a detects the peak before the reset. The hold signal is amplified and applied to one terminal a of an analog changeover switch (hereinafter referred to as changeover switch) 47.

The amplifier 46b in another receiving circuit 40b having the same configuration and connected in parallel with the receiving circuit 40a supplies its output signal to the other terminal of the changeover switch 47.

Note that the gate 42a of the a system and the gate 42b of the b system,
and a-series reset! - The gate pulse controller 34 and the reset pulse controller 35 respectively control the reset device 45a and the reset device 45b of the b system so that they operate alternately. Then, the changeover switch 47 is controlled by the signal changeover pulse controller 36 so that the output signals of the receiving circuits 40a, 40b of the a system and the b system are taken out alternately.

A series of signal sequences selected and extracted by the changeover switch 47 are amplified by a buffer amplifier 48 at the next stage. The output signal S<b>2 of the buffer amplifier 48 is sent to the image memory 30 . The image memory 30 samples the sent signal S<b>2 using the sampling pulse SK, sequentially A/D converts it, and stores it. In this case, the address is
Y position pulse SY from Y constant scanning 23 and X71'ff and Z from XZL1 position pulse controller 31
The image data stored in the image memory 30 determined by ii) is supplied to the CRT monitor 51 after being subjected to various signal processing by the image processing device 50. The CRT monitor 51 visualizes the supplied image data and displays the internal structure of the sample 22. Note that the capture of image data is started by a reset operation of the reset switch 52.

Next, the operation of this apparatus configured as described above will be explained.

First, when the reset switch 52 is turned on, S in FIG.
A reset signal such as R is input to the image memory 30 and the image processing device 50, and memory clearing, address reset, etc. are performed.

Therefore, the XY constant scan 23 is operated to scan the acoustic lens 21 and the sample 22 relatively in the XY constant manner. At this time, first one step scan is performed in the Y direction, and then a line scan is performed in the X direction. The position pulse SY in the Y scan is transmitted to the image memory 30, and the position pulse SY in the X scan is transmitted to the image memory 30.
The two pulses SX are input to the synchronization circuit 25. When the tally pulse CK from the reference tally clock generator 24, in which one point in this case corresponds to a point on the XY plane of the sample 22, is given to the synchronization circuit 25, it is synchronized with the previous pulse SX, and a transmission trigger pulse TT is generated. do. When this transmission trigger pulse TT is input to the transmission pulse generator 26, the generator 26 generates a high voltage pulse with a narrow pulse width as shown as So in the signal S of FIG. When this pulse So passes through the circulator 27 and is applied to the piezoelectric transducer 20, electro-acoustic conversion of the pulse So is performed and an ultrasonic wave is generated. This ultrasonic wave is converted into a focused spherical wave by the acoustic lens 21, and is passed through the water 6 to the sample 22.
incident on the Among the ultrasonic waves that have been transmitted, scattered, reflected, and absorbed by the sample 22, the reflected waves reflected on the sample surface or inside the sample return to the acoustic lens 21 and are converted from ultrasonic waves into electrical signals by the piezoelectric transducer 20. is,
The signal S(
α, β.

γ). The reflected signal high-frequency amplified by the preamplifier 28 is sent to two receiving circuits 40a and 40 having a parallel configuration.
It is simultaneously supplied to amplifiers 41a and 41b at 0b.

On the other hand, when the reference tally clock CK and the transmission trigger pulse TT are input to the synchronous frequency divider circuit 32, the second
A divided-by-2 pulse synchronized with the reference tarlock CK, such as SD in the figure, is generated. When this pulse SD is input to the gate pulse controller 34, as shown in G and G in FIG.
input as a control pulse. Each gate 42a, 42b
is set to be ON when G, G is H, and OFF when it is L, so that the amplifiers 41a, 4
Reflected signals α and β amplified by 1b.

γ is gated alternately like Sa3 and Sbl in FIG. 2 and is supplied to amplifiers 43a, 43b. Amplifier 43
The signal amplified by peak detectors 44a and 43b is transmitted to peak detectors 44a and 43b.
Each peak value is detected and held at 44b. The state in which this peak value is maintained is the state in which the gates 42a and 4
2b needs to be reset before turning on next time. To cope with this, the reset pulse controller 35 outputs reset pulse signals Ra and Rb upon receiving the signal SD from the synchronous frequency divider circuit 32. This signal Ra,
When Rh is given to the reset devices 45a and 45b, the reset devices 45a and 45b turn O at each time point.
N, and the peak detectors 44a and 44b are reset. The time t written in the Ra and Rb sections of Figure 2
r is the time width from when the gate is turned on until it is turned off. At this time, H width tr and reset pulses Ra, R
The sum of b and the time width is set to be shorter than one period of the signal SD. The waveform of the reflected signal peak-held and then reset is Sa2. It will be as shown as Sb2. This signal is amplified by amplifiers 46a and 46b, respectively, and input to each terminal of changeover switch 47. When the signal SS from the signal switching pulse controller 36 is H, the changeover switch 47 switches to the a side, and the signal SS
When is L, it switches to the b system side. Depending on the switching operation of the changeover switch 47, the output signal of the amplifier 46a or the amplifier 46b is selectively extracted. The extracted signals pass through the buffer amplifier 48 as a series of signals, and are applied to the image memory 30 as a signal S2 in FIG.

Based on the two-position information set by the two-position setter 33, the Xz position pulse controller 31 generates a pulse SP at a time tz delayed from the falling edge of the transmission trigger pulse TT.

This pulse SP sets an address corresponding to the X position of the image memory 30, and also sets a start address for taking in image data in two directions (depth direction). Therefore, for example, a sampling pulse SK delayed by a time ts is generated by the delay circuit 29 so that the values at α', β', and γ' in S■ in FIG. give to By doing so, only two peak values of reflected waves in two directions at a certain X position are A/D converted and recorded as digital signals. The above number ℃ is the number of divisions in the Z direction. For example, if n points are taken in the X direction, for example n = 512, in the X scan of the XY constant scan 23 for an operation of 0 or more with λ = 32, So-called B-mode image data of "n points in the X direction" and "2 points in the Xrz direction" is recorded in the image memory 30. If m Y scans are performed in the XY constant scan 23, for example, m=512, three-dimensional internal image data of rnXmXβ is taken into the image memory 30. The captured image data is subjected to processing such as image signal conversion in the next-stage image processing device 50, and then sent to the CRT monitor 51. Thus, an image showing the internal structure of the sample is displayed on the CRT monitor 51.

In this embodiment, the peak values of the reflected waves from inside the sample 22 are alternately detected by the two-system parallel elliptical receiving circuits 40a and 40b, so that the peak values of the reflected waves are not omitted. It can be detected accurately without.

Note that in the above embodiment, a receiving circuit with a parallel configuration of two systems is illustrated, but a receiving circuit with a parallel configuration of three or more systems may be used.In addition, in the above embodiment, an example is shown in which a peak detector is used as the detection means. However, other detection means such as a quadrature detector or a phase detector 1 may also be used.

FIG. 3 is a block diagram showing the configuration of the main parts of the second embodiment of the present invention. This embodiment is different from the first embodiment described above. In the embodiment, the signal SD is obtained by dividing the reference clock by two.
In contrast to the gate control, etc., performed in this embodiment, control is performed using signals with different duty ratios.

As shown in FIG. 3, a synchronous/arbitrary duty generation circuit 60
, and an optional duty determiner 61 are added. The synchronous arbitrary duty generating circuit 60 changes the duty of the reference tally clock CK generated by the reference tally clock generator 24 to an arbitrary duty, and then outputs the duty of the reference tally clock CK generated by the reference tally clock generator 24 to an arbitrary duty. XZ position pulse controller 31. This circuit supplies the synchronous frequency divider circuit 32, and the arbitrary duty setter 61 is for setting a desired duty.

FIG. 4 is a diagram showing the operation timing of the circuit shown in FIG. 3. The operation will be explained below with reference to FIG. 4.

Reference clock C sent from reference clock generator 24
In order to change the duty of K, an arbitrary duty generator 6 is used.
Perform the duty setting operation in step 1. Then, "-
According to the setting operation described above, the synchronous arbitrary duty generation circuit 60
is activated, and a pulse train is generated in which the duty is successively different, as shown at 81 in FIG. Based on this pulse train S'F, delay circuit IK29. XZ position pulse controller l-mouth 31. The synchronous frequency divider circuit 32 is activated. Therefore, the signals SK, SP, and SD become as shown in FIG. As a result, the time widths controlled by the gates 42a and 42b become different, and the ratio of time division in the Z direction (depth direction) when detecting reflected waves of ultrasonic waves changes to a desired state. Become. Therefore, the material of sample 22! f
For example, in the case of a sample with a structure in which two media with different sound velocities are connected in the depth direction, it is possible to capture the reflected waves by dividing them arbitrarily. By making the time division finer and coarsening the time division width in areas where the speed of sound is slow to capture reflected waves of ultrasound, it is possible to sample from the surface to the inside or back surface at equal intervals in the Z direction, and the difference in sound speed can be It is possible to remove image distortion due to For example, even in the case of samples made of the same medium, by making the time division narrower for a certain depth region and coarser for other depth regions, it is possible to It is possible to display the structure in an enlarged or reduced state9.Thus, in this embodiment, the gate 0NOFF
Since the timing duty can be arbitrarily changed, there is an advantage that the image in the depth direction of the sample 22 can be easily expanded or contracted.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

〔Effect of the invention〕

According to the present invention, a receiver is equipped with a gate that can separate and extract reflected signals within a predetermined time area and introduce the signals, and a detector that detects the reflected signals introduced by the gate and detects information such as the intensity of the reflected waves. Connect multiple circuits in parallel to create a receiving circuit group'! By controlling the gates of each system in this receiving circuit group, the receiving circuits of each system are sequentially and periodically operated, and the information signals detected by the receiving circuits of each system are sequentially selected and extracted. A series of signal strings and none,
By processing this signal sequence and displaying an image of the acoustic internal structure of the object to be measured, information such as the reflected wave intensity indicating the internal M P of the object to be measured can be accurately and
It is possible to provide an ultrasonic microscope @ hammer that can accurately detect images in a situation that does not occur, and can capture and display A-mode information, B-mode information, three-dimensional information, etc.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a first embodiment of the present invention,
Figure 2 is a waveform diagram showing the operation timing of the same embodiment;
The figure is a block diagram showing the configuration of the main parts of the second embodiment of the present invention, and FIG. 4 is a waveform diagram showing the operation timing of the second embodiment. FIGS. 5(a) and 5(b) are block diagrams showing conventional examples,
FIGS. 6(a) and 6(b) are waveform diagrams showing the operation timing of the conventional example. 20... Piezoelectric transformer, 21... Acoustic lens, 22-... Sample (measurement object), 40a, 40b.
...Two-system receiving circuit, 42a, 42b...gate,
44a, 44b - peak detector, 45a, 45b...
Reset device, 47...analog type changeover switch. Applicant's agent Patent attorney Atsushi Tsuboi

Claims (1)

[Claims] A focused spherical wave of ultrasonic waves is generated using an acoustic lens, and reflected waves from the surface and inside of the object to be measured are captured again by the acoustic lens to perform acoustic-electrical conversion, and the reflected signals are converted into In an ultrasonic microscope that can be taken out and displayed, there is a gate that can be introduced by separating and extracting reflected signals within a predetermined time area, and a detection device that detects the reflected signals introduced by this gate and detects information such as reflected wave intensity. a receiving circuit group comprising a plurality of receiving circuits connected in parallel, and a control means for sequentially and periodically operating the receiving circuits of each system by controlling gates of each system in the receiving circuit group; , means for sequentially selecting and extracting the information signals detected by the receiving circuits of each system which are operated periodically by the control means to form a series of signal trains; and means for processing the signal train obtained by this means. 1. An ultrasonic microscope characterized by comprising means for displaying an image of the acoustic internal structure of an object to be measured.