JPS58218646A - Ultrasonic microscope - Google Patents

Abstract

PURPOSE:To eliminate an unnecessary reflected wave signal in an observing lens, and to obtain a necessary reflected wave signal with high sensitivity, by providing each acoustic lens for observing and compensation a sample. CONSTITUTION:An ultrasonic wave is emitted through acoustic lenses 26a, 26b whose shape and physical characteristic are equal to each other, and also its reflected wave is converted to an electric signal by electroacoustic transducing elements 25a, 25b. Also, the lens 26a and the lens 26b are used for observing a sample and for compensation respectively. An output from the element 25a corresponding to the lens 26a is compensated by a reflected wave signal in the inside of the lens 26b mainly, which is obtained from the element 25b corresponding to the lens 26b.

Description

[Detailed description of the invention] The present invention relates to an ultrasound microscope.

Various types of ultrasonic microscopes have been proposed in the past, including one having the configuration shown in FIG. 1, for example. In this ultrasonic microscope, a high-frequency pulse generator 1 oscillates an ultra-high frequency burst wave electric signal, which is supplied to a piezoelectric transducer 8 via a circulator 2, where the electric signal is converted into an ultrasonic wave and is transmitted through an acoustic lens. A sample stage that moves two-dimensionally in the X-axis and Y-axis directions by the scanning controller 6 via the (ultrasonic focusing lens) 4 and the liquid 6? A spot is projected onto the sample 8 placed above. In addition, the reflected waves from the sample 8 are collected by an acoustic lens 4, converted into electrical signals by a piezoelectric transducer 3, and supplied to a gate circuit 9 via a circulator 2. A signal corresponding to the reflected wave is extracted, and this is amplified and detected by the amplification/detection circuit IO to obtain a detection signal corresponding to the intensity of the reflected wave, and this detection signal is used as a brightness signal to perform scanning control by the scan converter 11. Sample stage 7 with bag [a
The ultrasonic image is displayed on the cathode tube 12 in synchronization with the scanning. The operations of the high frequency pulse generator 11 scan controller t6, gate circuit 9 and scan converter 11 are controlled by a control circuit 1B.

In the ultrasonic microscope described above, the ultrasonic waves emitted from the piezoelectric transducer 3 to the acoustic lens 4 are multiplexed between the concave lens portion 4a of the acoustic lens 4 and the piezoelectric transducer 3, as shown in FIG. At the same time, the waves are reflected diffusely from the lens portion 4a to the side wall 4b, and these reflected waves within the acoustic lens 4 are converted into electrical signals by the piezoelectric transducer 8 and supplied to the gate circuit 9 via the circulator 2.

Figure 8 shows the distribution of signals input to the gate circuit 9 when there is no sample 8, where Po represents the leakage signal from the circulator 2 of the high frequency pulse generator l, P , P
and P8 is the first point between the piezoelectric transformer 2 and the lens portion 4a. 2nd and 8th
represents the multiple reflected wave signal of It is reflected by the lens part 4a,
The diffusely reflected wave signal that enters the piezoelectric transducer 3 via the side wall 4b is a first reflected wave signal P0 and a second reflected wave signal P2.
and between the second reflected wave signal P2 and the third reflected wave signal P8.
appears between.

Here, if the desired reflected wave signal from the sample 8 appears between the first reflected wave signal P□ and the second reflected wave signal P2 in example (8), this reflected wave signal is a diffusely reflected wave signal. Because of this interference, there is a drawback that even if the gate circuit 9 extracts it, there are many noise components and it is not possible to obtain an ultrasonic image with good image quality.

Note that the above-mentioned diffused reflection occurs in the same way even if an antireflection film is provided on the lens portion 4a.

An object of the present invention is to provide an ultrasonic microscope appropriately configured to eliminate the above-mentioned drawbacks, effectively remove unnecessary reflected wave signals within an acoustic lens, and obtain reflected wave signals from an observation sample with high sensitivity. This is what we are trying to provide.

The ultrasonic microscope of the present invention includes two acoustic lenses having substantially the same shape and physical characteristics, and each of these two acoustic lenses is provided with an ultrasonic microscope that generates ultrasonic waves through each acoustic lens and emits reflected waves. An electroacoustic transducer element for converting into an electric signal, one of the two acoustic lenses described in 1 above is used for sample observation, the other □ is used for correction, and the electroacoustic transducer element corresponds to this correction acoustic lens. The present invention is characterized in that the output from the electroacoustic transducer corresponding to the sample observation acoustic lens is corrected based on the reflected wave signal inside the lens (4) mainly obtained from the acoustic lens.

The present invention will be described in detail below with reference to the drawings.

FIG. 4 is a diagram showing the configuration of an example of the ultrasonic microscope of the present invention. In this example, a high-frequency pulse generator 22 is controlled by a control circuit 21 to generate a burst wave, which is divided into two by a distributor 23 and one is supplied to a piezoelectric transducer 25a via a circulator 24a for sample observation. converts electrical signals into ultrasonic waves and transmits them to the acoustic lens 26.
a and liquid 27 onto a sample 29 placed on a sample stage 28, and the other is supplied for correction to a piezoelectric transducer 25b via a circulator 24b, where the electric signal is converted into an ultrasonic wave and acoustic It is projected into the liquid 31 contained in the container 80 through the lens gab. The piezoelectric transducer 25a + z5b and the acoustic lenses gaa and g6b have substantially the same shape and physical characteristics, and the liquid 81 sufficiently attenuates the ultrasonic waves projected from the acoustic lens gab so that the reflected waves become piezoelectric. The depth is such that it cannot be detected by the transducer 25b. In this way, only the reflected wave signal within the acoustic lens gBb can be obtained from the piezoelectric transducer 25b, and the reflected wave signal from the piezoelectric transducer 25a that is almost the same as the reflected wave signal obtained from the piezoelectric transducer 25b can be obtained from the sample. The acoustic lens 26a and the sample 29 are relatively two-dimensionally moved in the X-axis and Y-axis directions by the control circuit 21 via the scanning control device 82.

The reflected wave signal obtained from the piezoelectric transducer 25a is supplied to an attenuator 88 via the circulator 24a, where its level is adjusted to be comparable to that of the reflected wave signal obtained from the piezoelectric transducer 25b, and a high frequency differential amplifier is used. 84 non-inverting input terminal. Further, the reflected wave signal obtained from the piezoelectric transducer 25b is supplied to the phase shifter 85 via the circulator 24b, where the phase with the reflected wave signal obtained from the piezoelectric transducer 25a is adjusted, and the inverted input of the high frequency differential amplifier 84 is performed. Supply to the terminal. In this way, only the sample reflected wave signal from which unnecessary reflected wave signals within the acoustic lens 26a have been canceled out can be obtained from the high frequency differential amplifier 84. This sample reflected wave signal is supplied to the detection circuit 86 to obtain a detection signal corresponding to the intensity of the reflected wave, and from this detection signal, a gate control pulse from the control circuit 21 is sent to the gate circuit 87 to detect the sample 2.
Excluding the multiple reflected wave signals of the reflected waves of 9, only the direct sample reflected wave signal is extracted, and this is supplied as a luminance signal to the scan converter 89 via the video processing circuit 38. An ultrasonic image is displayed on the cathode tube 40 in synchronization with the relative two-dimensional scanning of the acoustic lens 26a and the sample stage 28.

Note that the present invention is not limited to the case where an ultrasonic image of the sample 29 is displayed on the cathode ray tube 40 as described above. As a result, (7) can be effectively applied to investigating the characteristics of a sample.

As described above, in the present invention, two acoustic lenses having substantially the same shape and physical characteristics are used, one of which is used for sample observation, and the other is used for correction, and electroacoustic conversion corresponding to the correction acoustic lens is used. Since the output from the electroacoustic conversion element corresponding to the acoustic lens for sample observation is corrected by the reflected wave signal obtained from the element mainly inside the acoustic lens, unnecessary reflected waves within the acoustic lens for sample observation are corrected. Signals can be effectively removed, and only the required reflected wave signals from the observation sample can always be obtained with high sensitivity.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the configuration of a conventional ultrasound microscope, Figure 2 is a diagram showing how ultrasound is reflected within the acoustic lens, and Figure 8 is a diagram showing reflected waves caused by unnecessary reflection within the acoustic lens. FIG. 4 is a waveform diagram showing the aspect of the signal. FIG. 4 is a diagram showing the configuration of an example of the ultrasonic B microscope of the present invention. (8) 21... Control circuit 22... High frequency pulse generator 28... Minute device 24a, 24b... Circulator 25 a, 25 b
...Piezoelectric transducer 26a, 26
b...Acoustic lens 27...Liquid 28.
...Sample stand 29...Sample 30...Container 3
1...Liquid 82...Scanning control device 38.
...Attenuator 34...High frequency differential amplifier a5.
... Phase shifter 86 ... Detection circuit 87 ... Gate circuit 88 ... Video process circuit 39 ... Scan converter 40 ... Cathode tube Figure 1

Claims (1)

[Claims] L: Two acoustic lenses with approximately the same shape and physical characteristics, and an electroacoustic sensor installed in each of these two acoustic lenses that generates ultrasonic waves through each acoustic lens and converts the reflected waves into electrical signals. one of the two acoustic lenses is used for sample observation and the other is used for correction, and a reflected wave signal mainly inside the acoustic lens obtained from the electroacoustic conversion element corresponding to the correction acoustic lens. An ultrasonic microscope characterized in that it is configured to correct an output from an electroacoustic transducer corresponding to the acoustic lens for sample observation.