JPH0136586B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention makes it possible to display information about a sample that cannot be obtained with conventional black and white display by artificially coloring a visible image produced by a two-dimensional scanning ultrasound microscope. This invention relates to a pseudo-color display type ultrasound microscope.

FIG. 1 shows an example of the configuration of a well-known two-dimensional scanning ultrasound microscope.

1 is a control pulse generator that generates a control pulse signal for emitting ultrasonic waves as burst waves; 2 is a high-frequency pulse generator that generates an ultrasonic burst wave electric signal according to the control pulse signal; 3 is a circulator; 4 5 is a piezoelectric transducer, 5 is an acoustic lens that transmits and receives ultrasonic waves, 6 is a liquid that is an ultrasound transmission medium, 7 is a sample to be observed, 8 is a sample stage, and 9 is a gate to extract only information about sample 7. 10 is a reflected wave signal receiver including a gate section, an amplification section and a detection section; 11 is a two-dimensional (X −
Y) Two-dimensional scanning control device for scanning, 12
is a scan converter which performs scan synchronization as a luminance signal at a corresponding position on the sample surface, stores it, and outputs it to an image display device 13, for example, a black and white monitor using a cathode ray tube, so that the image can be reproduced.

Next, its operation will be briefly explained. Generate a short-time pulse signal from the control pulse generator 1,
A burst wave electrical signal is generated from a high frequency pulse generator 2 for a time corresponding to the pulse width, and is supplied to a piezoelectric transducer 4 via a circulator 3. This piezoelectric transducer converts the burst wave electrical signal into an ultrasonic wave and converts it into an acoustic lens 5.
As a result, the particles are focused and a minute spot is formed on the surface of the sample 7 through the liquid 6.

The ultrasonic waves that reach the sample 7 are reflected according to the acoustic characteristics of the sample 7, and the reflected waves are again collected by the acoustic lens 5 and converted into electrical signals by the piezoelectric transducer 4, which sends the circulator 3. The signal is input to the receiver 10 via. FIG. 2a shows the time course of the input signal. That is, in the same waveform diagram, P is the direct receiver 1 from the high frequency pulse generator 2 leaking through the circulator 3.
R is a leakage burst wave electric signal input to 0, and R is a primary burst wave that is reflected from the sample 7 and is converted into an electric signal by the piezoelectric transducer 4 and input to the receiver 10 via the circulator 3. These are wavy reflected wave signals, all of which are expressed by envelopes.

In order to extract only the direct first-order reflected wave signal R from the sample 7 and eliminate leakage burst wave signals P and unnecessary reflected wave signals diffracted within the acoustic lens 5, high-frequency signals are generated from the control pulse generator 1. The control pulse signal to the pulse generator 2 is branched and added to the delayed pulse generator 9, where the control pulse signal is used as a reference to match the timing of the primary reflected wave signal R as shown in FIG. 2b. By generating a delayed pulse signal and using this as a gate signal to operate the gate section in the receiver 10, only the primary reflected wave signal R is extracted, which is amplified and detected within the receiver 10. A detection signal corresponding to the reflected wave signal R is obtained.

This detection signal is obtained one after another at the control pulse signal period according to the relative two-dimensional scanning of the sample 7 and the acoustic lens 4, so it is guided to the scan converter 12 and corresponds to the scanning position on the surface of the sample 7. The luminance signal is recorded one after another in relation to the control signal from the two-dimensional scanning control device, is read out using a predetermined scanning method, and is reproduced as an image on a cathode ray tube type black and white monitor 13 for observation. That's what I do.

The conventional ultrasonic microscope described above can visualize a black and white optical image depending on the strength of acoustic reflection on the surface of the sample 7, but it is not possible to determine whether the surface of the sample 7 is at the optimal focus position by simply observing the image. In this case, or in the case of out-of-focus, it is not easy to judge distance from the focal position, and therefore, the focus adjustment is extremely troublesome and time-consuming.

SUMMARY OF THE INVENTION In order to eliminate the above-mentioned drawbacks, it is an object of the present invention to provide a pseudo-color display type ultrasound microscope that can very easily determine the focused or out-of-focus state from the colored state of the ultrasound image. That is.

In order to achieve this purpose, the sample and the acoustic lens are moved relatively to scan the sample in two dimensions, and the acoustic lens projects ultrasonic waves onto the sample, and the reflected waves are received and detected. , in a two-dimensional scanning ultrasound microscope that sequentially obtains detection signals corresponding to the scanning position of the sample and displays them as an image in synchronization with the two-dimensional scanning,
pulse generating means for generating at least two types of sampling pulses that are synchronized with a pulse signal for driving a piezoelectric transducer for generating ultrasonic waves and having a slight time difference; and sampling the detected signal using the sampling pulse. A sample holding means for holding a sample, a color signal generating means for specifying an arbitrary color for each of the held signals and converting these into a color signal, and a display means for displaying this color signal as a color image. , one of the sampling pulses is generated in accordance with the generation timing of the detection signal, which is limited to when the acoustic lens is in focus on the sample, and a specific color is obtained corresponding to the sampling pulse. The color image of the camera is characterized in that it displays that the camera is in focus.

The present invention will be explained below with reference to the drawings.

FIG. 3 is a block diagram showing an example of the configuration of an embodiment of the present invention, and the same parts as those of the conventional device shown in FIG. 1 are designated by the same reference numerals.

In FIG. 3, 14 amplifies and amplifies the received signal corresponding to the ultrasonic reflection signal R' shown in FIG. 4a.
This is a receiver for wave detection. 15a, 15b and 15c have the timing of the detection signal from the receiver 14 corresponding to the ultrasonic reflection signal R' with reference to the control pulse signal supplied from the control pulse generator 1, and are mutually synchronized. This is a delayed pulse generator for generating delayed pulse signals with a slight time difference between the two. 16a, 16b, and 16c are configured to sample and hold the detected signal from the receiver 14 by converting each delayed pulse signal generated by each of the delayed pulse generators 15a, 15b, and 15c into sampling pulses. It is a sample and hold device, 17a, 1
Reference numerals 7b and 17c are amplifiers for amplifying the respective outputs of the sample-and-hold devices 16a, 16b, and 16c, respectively. 18 is each amplifier 1
For the outputs of 7a, 17b, and 17c, colors such as red, green, and blue are arbitrarily specified, and these signals are applied to the sample 7 using control signals from the scanning controller 11.
The color signal of the part corresponding to the position on the surface is recorded in synchronization with the relative scanning of the acoustic lens 5 and the sample 7, and the color designation signal recorded in this way is converted into a color signal and displayed in color on the color monitor 19. This is a color scan converter configured to output a signal that can be displayed as an image. It should be noted that the parts indicated by the same reference numerals as in FIG. 1 are the same as those in FIG. 1, so the explanation thereof will be omitted. Regarding the operation of the embodiment of the present invention as described above, in order to simplify the explanation, only the points different from the conventional configuration shown in FIG. 1 will be explained.

As shown in FIG. 2a, the signals input to the receiver 14 are a leakage burst wave electric signal P input directly from the high-frequency pulse generator 2 leaking through the circulator 3 and an ultrasonic reflected wave from the sample 7. This is the reflected wave signal R converted into . Therefore, both signals are amplified and detected by the receiver and extracted. These detected signals are shown in Figure 4a as P′ and
Denoted by R′. Figure b shows a detection signal R' corresponding to the first reflected wave signal among those detected signals _. , C ₂ and C ₃ , three series of delayed pulse signals having three timings having a slight time difference from each other are transmitted to each delayed pulse generator 15a, 15b based on the control pulse signal from the control pulse generator. , 15c.

Each of these delay pulse generators 15a, 15b, 1
3 with a slight time difference from each other generated from 5c
The delayed pulse signals C ₁ , C ₂ , and C ₃ of the series are guided to each of the three sets of sample-and-hold devices 16a, 16b, and 16c corresponding to the three series, and the delayed pulse signals C ₁ of the three series are guided. , C ₂ and C ₃ as sampling pulses and input them to each sample/hold device 16a, 16b, 16c.
Reflected wave detection signal from receiver 14 shown in Figure b
Sample and hold only R'. These sampled and held output signals are suitably amplified by respective amplifiers 17a, 17b, and 17c, and then guided to a color/scan converter 18.

In the color/scan converter 18,
An arbitrary color is specified for the sample/hold signals for each series, and the relative scanning of the acoustic lens 5 and the sample 9 is synchronized by the control signal from the scan control device 11, and the luminance signal at the corresponding position of the sample 7 is Each image is recorded so that it will be played back as follows. If each color designated signal is read out as a color signal and the image is reproduced by the color monitor 19, for example, a color monitor constituted by a color cathode ray tube, the timing of the reflected wave detection signal shown in FIG. Since each image constituting the reproduced image is colored according to the waveform and the amplitude value of each part of the waveform, it is easy to determine whether the acoustic lens 5 is in focus or out of focus on the sample 7 from the color of the reproduced image. can be observed. That is, in the present invention, among the delayed pulse signals shown in FIG. 4c,
Assume that the timing of the C ₂ signal matches the timing of the reflected wave detection signal that should be obtained at the time of focusing, and the signals sampled and held at the timing of C ₁ , C ₂ , and C ₃ are divided into red, green, and blue signals, respectively. If the color is specified as , the sample/hold value by the delayed pulse signal of _C2 will be the highest value when in focus, and when out of focus, the sample/hold value will be the highest value depending on the direction of out of focus.
The sample/hold value due to the C ₁ or C ₃ delayed pulse signal increases, indicating that the part of the sample corresponding to the dark green part on the color monitor image is the focal plane. In addition, the mixing ratio of each color changes for each image depending on the degree of coloring, so it is easy to observe out-of-focus conditions such as in which direction the focus is shifted depending on the degree of coloring, the color of coloring, and the brightness. can do. Furthermore, since the waveform of the reflected wave detection signal R' changes greatly depending on the acoustic characteristics of the sample 7, the proportion of the three-color mixture also changes depending on the shape of the waveform, and the mixed color and the adjacent image The acoustic properties of each part of the sample 7 can also be observed from the difference in brightness between the parts.

Note that the width of the sampling pulses of each series is changed by making each pulse width Δt wider than the example shown in c of the same figure, as shown by C ₁ ′, C ₂ ′, and C ₃ ′ in Fig. 4 d. The timings may be such that they overlap by a very small amount of time; in short, it is sufficient to provide a slight time difference between the timings of the sampling pulses of each series.

Further, in the above embodiment, the reflected wave detection signal R' taken out from the receiver 14 was explained as being obtained by detecting the primary reflected wave from the sample 7, but the present invention is not limited to this. Rather than detecting any second or subsequent reflected waves or interference waves of reflected waves within the acoustic lens 5, a detected signal is detected by each delayed pulse generator 15a, 15b,
Sample and hold may be performed using three series of delayed pulses from 15c. The color designation is not limited to red, green, and blue, and any two or more colors may be used. In that case, the number of delay pulse generators, sample-and-hold devices, and amplifiers for amplifying their outputs is determined in accordance with the number of colors specified.

As is clear from the above embodiments, the present invention has a detection signal of an ultrasonic reflection signal having information about one point on a sample, which has timings with minute time differences, one of which is at the optimal focal point of an acoustic lens. Samples and holds are performed one after another in relation to the relative two-dimensional scanning between the acoustic lens and the sample using two or more series of sampling pulses that correspond to the timing at which the ultrasonic reflection signal of maximum intensity is obtained when the sample surface is placed on the surface of the sample. Since a color image is displayed using two or more series of color signals obtained by specifying colors for each series of hold output signals, the focal state of the acoustic lens is displayed by the difference in color. Therefore, it is possible to check at a glance not only whether or not the object is in focus, but also the direction in which it is out of focus, making it easy to adjust the focus. This is the timing at which the ultrasonic reflection signal of maximum intensity is obtained when the sample surface is placed at the optimal focus position of the acoustic lens.

In addition, when there is a change in the acoustic characteristics just below the sample surface, conventional ultrasound microscopes simply read the strength and weakness of the ultrasound reflected waves, which is a combination of information on the sample surface and just below the surface, and display it as a black and white image. However, according to the present invention, changes in acoustic characteristics can be observed on the displayed color image based on color changes and brightness differences between adjacent parts of the image. This has the effect of simultaneously displaying various types of information about a sample that could not be observed using conventional ultrasonic microscopes.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an example of the configuration of a conventional two-dimensional scanning ultrasound microscope, Fig. 2 is a waveform diagram for explaining the operation of the one shown in Fig. 1, and Fig. 3 is an embodiment of the present invention. A block diagram showing an example of the configuration of
FIG. 4 is a waveform diagram for explaining the operation. DESCRIPTION OF SYMBOLS 1... Control pulse generator, 2... High frequency pulse generator, 3... Circulator, 4... Piezoelectric transducer, 5... Acoustic lens, 6... Liquid,
7... Sample, 8... Sample stage, 11... Two-dimensional scanning control device, 14... Receiver, 15a, 15b, 1
5c...Delayed pulse generator, 16a, 16b, 1
6c...Sample/hold device, 17a, 17
b, 17c...Amplifier, 18...Color scan converter, 19...Color monitor.

Claims (1)

[Claims] 1. Move the sample and the acoustic lens relatively to scan the sample in two dimensions, project ultrasonic waves onto the sample from the acoustic lens, and receive and detect the reflected waves to locate the sample at the scanning position. In a two-dimensional scanning ultrasound microscope that obtains corresponding detection signals one after another and displays the images in synchronization with the two-dimensional scanning, the detection signals are synchronized with a pulse signal for driving a piezoelectric transducer for generating ultrasonic waves. ,
and pulse generating means for generating at least two types of sampling pulses having a slight time difference;
sample and hold means for sampling and holding the detected signal using the sampling pulse; color signal generation means for specifying arbitrary colors for each of the held signals and converting them into color signals; and the color signal. display means for displaying the sample as a color image, generating one of the sampling pulses in accordance with the generation timing of the detection signal obtained when the acoustic lens is in focus on the sample; A pseudo-color display type ultrasound microscope that displays a color image of a specific color obtained in response to a sampling pulse to indicate that it is in focus.