JPH0560733A - Ultrasonic microscope - Google Patents

Abstract

PURPOSE:To obtain an ultrasonic microscope which enables measurement of dynamic properties such as elasticity of a liquid sample as well without any hindrance. CONSTITUTION:An ultrasonic microscope has a transducer 1 which transmits and receives an ultrasonic wave through an acoustic lens 4, a sample stage 2 which holds a sample S at a position whereat the ultrasonic wave from the acoustic lens 4 converges through a propagation medium W, and a scanning means 3 which displaces this sample stage 2 and the transducer 1 relatively. A film body 9 interposed between the sample S on the sample stage 2 and the propagation medium W is provided and this film body 9 is formed of a substance having an acoustic impedance being approximate to the one of the propagation medium W.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic microscope used for measuring mechanical properties such as elasticity, density and viscosity of a sample by ultrasonic waves.

[0002]

2. Description of the Related Art Ultrasonic waves reflect mechanical properties such as elasticity of a substance that is reflected or transmitted, and provide information inside the substance that cannot be obtained by light or electron beams. Then, the ultrasonic microscope is configured to obtain a fine image of the sample by utilizing the characteristics of this ultrasonic wave, and FIG. 2 shows its schematic configuration.

As shown in FIG. 2, the ultrasonic microscope includes an ultrasonic transducer 21, a sample stage 22, and a scanning means 23.
And the transducer 21 is an acoustic lens 2
4 and a piezoelectric thin film 25.

The acoustic lens 24 is made of a columnar crystal such as sapphire or quartz glass. One end surface of the acoustic lens 24 is an optically polished flat surface, while the other end is provided with a minute hemispherical concave portion. There is. The piezoelectric thin film 25 is provided on the flat surface at one end of the acoustic lens 24. This piezoelectric thin film 2
5 is excited by a high frequency pulse from the pulse oscillator 26 to generate an ultrasonic wave, and also converts an ultrasonic echo transmitted through the acoustic lens 24 into an electric signal and gives it to the receiver 27. The receiver 27 amplifies and detects the electric signal, converts the electric signal into a video signal, and inputs the video signal to the display 28.

The sample table 22 holds the sample S placed at a position facing the acoustic lens 24, and between the sample S placed on the sample table 22 and the acoustic lens 24, An ultrasonic wave propagation medium W such as pure water is filled. The sample table 22 is driven to be displaced in the three-dimensional direction by the scanning means 23.

In the above structure, the ultrasonic wave generated by the piezoelectric thin film 25 is focused by the acoustic lens 24 into a thin beam of about 1 μm, and is irradiated onto the sample S through the propagation medium W. Also, with the irradiation of this ultrasonic beam,
Since the sample table 22 is three-dimensionally displaced, the sample S is scanned by the ultrasonic beam. Therefore, sample S
The ultrasonic echo from the ultrasonic wave is transmitted by the propagation medium W and the acoustic lens 2.
The signal is received by the piezoelectric thin film 25 through 4 and converted into an electric signal. This electrical signal is the sample S
By processing in synchronism with the scanning of, the fine two-dimensional image of the sample surface is obtained, and this image is displayed by the display 28.

[0007]

By the way, it is limited to the solid sample that properties such as elasticity are measured by using the conventional ultrasonic microscope. This is the sample S and the acoustic lens 24.
This is because it is necessary to fill an ultrasonic wave propagation medium W such as pure water between the two, and if the sample is liquid, the liquid sample must be dissolved and diffused in the propagation medium W. As a result, the boundary surface as the reflecting surface of the ultrasonic wave is destroyed, and the properties such as elasticity of the sample cannot be measured.

The present invention was devised in view of such inconveniences, and has no problem with liquid samples.
It is intended to provide an ultrasonic microscope capable of measuring mechanical properties such as elasticity.

[0009]

In order to achieve such an object, the present invention provides a transducer for transmitting and receiving an ultrasonic wave through an acoustic lens and a position where the ultrasonic wave from the acoustic lens is focused through a propagation medium. In an ultrasonic microscope having a sample table for holding a sample placed thereon and a scanning means for relatively displacing the sample table and the transducer, a sample placed on the sample table and a propagation medium are interposed between the sample table and the propagation medium. A film body to be mounted is provided, and the film body is made of a substance having an acoustic impedance close to that of the propagation medium.

[0010]

According to the above construction, even if the sample is in a liquid state, since the film body is interposed between the sample and the propagation medium, it is possible that the sample and the propagation medium are not mixed with each other. Absent. Moreover, since the film body has an acoustic impedance similar to that of the propagation medium, almost no ultrasonic waves are reflected at the boundary surface between the film body and the propagation medium, and the sample is liquid. Even if it does, the measurement can be performed by focusing on an arbitrary position of the liquid sample.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram showing a schematic configuration of an ultrasonic microscope according to this embodiment.

As shown in FIG. 1, the ultrasonic microscope of this embodiment holds a transducer 1 for transmitting and receiving ultrasonic waves and a sample S placed at a position where the ultrasonic waves from the transducer 1 are focused. It has a sample table 2 and a scanning means 3 for two-dimensionally displacing the sample table 2 with respect to the transducer 1, and the transducer 1 is one of the acoustic lenses 4 made of a columnar crystal such as sapphire or quartz glass. It is the same as the conventional ultrasonic microscope in that it is configured by providing the piezoelectric thin film 5 on the end face. This ultrasonic microscope also includes a pulse oscillator 6 for exciting the piezoelectric thin film 5 of the transducer 1, a receiver 7 for amplifying and detecting an electric signal from the piezoelectric thin film 5 to generate a video signal, and a receiver 7 for receiving the signal. It is the same as the conventional example in that it has a display 8 for displaying a video signal as an image in synchronization with the scanning of the sample S.

The ultrasonic microscope according to this embodiment is different from the conventional example in that a film body 9 is interposed between a sample S placed on a sample table 2 and a propagation medium W. That is, the body 9 is made of a substance having an acoustic impedance close to that of the propagation medium W.

As a concrete material for forming the film body 9, a polydimethylsiloxane film or a low density polyethylene film is used. Incidentally, the acoustic impedance (N · s / m ³ ) of these is about 1.4 × 10 ⁶ for pure water as a propagation medium, and about 1.1 × 10 ^{6 for} polydimethylsiloxane. The low density polyethylene is about 1.8 × 10 ⁶ .

When measuring properties such as elasticity of a liquid sample in the above-mentioned structure, first, the sample S is spread thinly (about 0.5 mm) on the sample table 2 and is placed on the sample S. After the film body 9 is brought into close contact, the propagation medium W is filled between the film body 9 and the acoustic lens 4. At this time, the sample S
Since the film body 9 is interposed between and the propagation medium W, the sample S and the propagation medium W cannot be mixed with each other.

After that, by applying a high frequency pulse from the pulse oscillator 6 to the piezoelectric thin film 5, ultrasonic waves are focused on the sample S through the acoustic lens 4 and the propagation medium W, and the sample is scanned by this ultrasonic beam. , Receives the ultrasonic echo from the sample S. At this time, since the film body 9 has an acoustic impedance close to the acoustic impedance of the propagation medium W, the ultrasonic beam emitted from the acoustic lens 4 is almost at the boundary surface between the propagation medium W and the film body 9. Since it will pass through without being reflected, sample S
It is possible to focus on an arbitrary position of, and the sample S can be measured at this position. Therefore, of the both surfaces of the film body 9, only the surface in contact with the sample S acts as if the sample S were in direct contact with the propagation medium W. As a result, a fine image showing mechanical properties such as elasticity of the liquid sample can be obtained.

By the way, the inventors of the present invention used a low-density polyethylene film having a thickness of 40 μm as the film body 9 and set the measurement frequency of 200 MHz to the elastic properties of the liquid resin (dispersion state of the filler and the matrix or It has been confirmed that a clear image can be obtained by measuring the (orientation of the functional filler).

[0019]

As described above, according to the present invention,
It is possible to obtain an image in which the liquid sample and the propagation medium do not mix with each other, and moreover, the propagation medium and the liquid sample form a clear boundary surface and are in direct contact with each other. It is possible to obtain an effect that mechanical properties such as can be measured without any trouble.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a schematic configuration of an ultrasonic microscope according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a schematic configuration of a conventional acoustic microscope.

[Explanation of symbols]

 1 Transducer 2 Sample stage 3 Scanning means 4 Acoustic lens 5 Piezoelectric thin film 9 Film body S Sample W Propagation medium

Claims (1)

[Claims] 1. A transducer (1) for transmitting and receiving ultrasonic waves through an acoustic lens (4), and a sample (S mounted at a position where ultrasonic waves from the acoustic lens (4) are focused through a propagation medium (W). ) Is held on the sample stage (2), and a scanning means (3) for relatively displacing the sample stage (2) and the transducer (1) is mounted on the sample stage (2). A film body (9) interposed between the placed sample (S) and the propagation medium (W) is provided, and the film body (9) is a substance having an acoustic impedance close to that of the propagation medium (W). An ultrasonic microscope characterized by being composed of.