JPS6097251A - Ultrasonic microscope - Google Patents

Abstract

PURPOSE:To omit the replacing work of an ultrasonic wave head every time the frequency is changed, by using the ultrasonic wave head, in which a plurality of piezoelectric elements are arranged in a concentric disk shape, so that a plurality of ultrasonic waves having different frequencies can be generated by one head. CONSTITUTION:A common lower electrode 12 is formed on one end surface 11a of an acoustic lens 11 comprising sapphire by evaporation. Another end surface 11b of the acoustic lens 11 has a concave spherical surface so as to have a lens action. Piezoelectric elements 13 and 14 comprising a piezoelectric material are provided in a concentric circle state on the lower electrode 12. Upper electrodes 15 and 16 are formed on the piezoelectric elements 13 and 14. The lower electrode 12 and the upper electrode 15 are directly connected to a signal source 17, and, e.g., an ultrasonic wave of 400MHz is generated. The upper electrode 16 can be selectively connected to the upper electrode 15 through a switch 18. Thus, e.g., an ultrasonic wave of 100MHz is generated. In this constitution, frequency can be changed without replacing an ultrasonic wave head.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an ultrasonic microscope, and particularly to an ultrasonic microscope capable of projecting low-frequency ultrasonic waves and high-frequency ultrasonic waves onto a sample.

Conventional technology The ultrasonic head conventionally used in ultrasonic microscopes is
An ultrasonic transducer is installed on one end surface of the acoustic lens,
The ultrasonic beam emitted from this ultrasonic transducer is focused by an acoustic lens and projected onto the sample. In this case, if a high frequency ultrasonic beam of 400 MHz is used, for example, the resolution will be high, but the depth of penetration into the sample will be shallow, making it impossible to observe the inside of the sample. on the other hand,
When a 100 MHz low-frequency ultrasonic beam is used, the depth of penetration into the sample increases, making it possible to observe the inside of the sample, but the resolution is reduced.

Therefore, the vicinity of the surface of the sample was observed using high-resolution high-frequency ultrasound, and the interior of the sample was observed using low-frequency ultrasound. Previously, in order to change the frequency, the ultrasound head had to be replaced each time an observation was made. However, it is very troublesome to replace the ultrasonic head in this way, and has the disadvantage that prompt observation is hindered.

Particularly, when the ultrasonic head is replaced, there is also a drawback that the influence of its weight and the cable for connecting it to an external circuit on the vibration device changes. In order to eliminate such drawbacks, it may be possible to attach multiple ultrasonic heads to a reportr and drive the heads to exchange the heads.
The disadvantage is that the mechanism of the revolver is very complicated and large. Furthermore, since the sound field changes by switching the ultrasonic head, there is also the drawback that observation within the same sound field is not possible.

OBJECTS OF THE INVENTION The object of the present invention is to eliminate the above-mentioned drawbacks and to provide an ultrasound microscope that allows the frequency of ultrasound waves to be switched extremely easily within the same sound field without replacing the ultrasound head. be.

Summary of the Invention The ultrasonic microscope of the present invention includes an ultrasonic head having a plurality of piezoelectric transducers arranged concentrically on the other end of an acoustic lens whose one end is a curved surface with a lens effect, and a plurality of piezoelectric transducers arranged in a concentric manner. The apparatus is characterized by comprising means for selectively generating a plurality of ultrasonic waves having different wavelengths by separately driving the apparatus.

Example Hereinafter, the present invention will be described in detail with reference to the drawings.

FIGS. 1A and 1B are a plan view and a sectional view showing the configuration of a conventional ultrasonic head, in which a pair of electrodes 2 and 8 are connected to one end surface 1a of an acoustic lens 1 made of an ultrasonic propagation medium such as sapphire. An ultrasonic transducer 5 sandwiching an element 4 is provided, and the other end surface 1b is a concave spherical surface to have a lens effect. Now, the radius of the piezoelectric transducer 5 is ρ. , the wavelength of the ultrasonic wave is λ, and the distance from the piezoelectric transducer 5 to the lens surface 1b is e, a sound field as shown in FIG. 2 is obtained. In FIG. 2, the values of are plotted. Normally, the acoustic lens of an ultrasound microscope generates coherent ultrasound, so if l is the wavelength of a low-frequency ultrasound when it is generated, λ1 is the wavelength, then the radius of the piezoelectric transducer 5 is ρ. is ρ. -v/EfE
It becomes 〒. Next, when generating ultrasonic waves of high frequency, for example 4 times the high frequency, with the same lens length e, the wavelength is 2L/
4 and becomes piezoelectric. In this way, even with the same lens length e, the radius ρ of the piezoelectric transducer 5. The frequency of the ultrasonic waves can be changed by changing the . That is,
When generating high frequency ultrasound waves, the radius of the piezoelectric transducer is smaller than when generating low frequency ultrasound waves. The present invention was made based on the confirmation and recognition of this fact.

FIGS. 8A and 8B are a plan view and a sectional view showing the configuration of an example of an ultrasonic head used in the ultrasonic microscope of the present invention. One end surface 11 of the acoustic lens 11 made of sapphire
A common lower electrode 12 is formed on a by vapor deposition. The other end surface lb of the acoustic lens 11 is a concave spherical surface and has a lens function. Piezoelectric elements 13 and 14 made of a piezoelectric material are provided concentrically on the lower electrode 12.

These can be formed accurately by uniformly sputtering a piezoelectric material and then patterning it using a mask.Furthermore, upper electrodes 15 and 16 are formed by vapor depositing on these piezoelectric elements 18 and 14, respectively. do.

5, in this example, the lower electrode 12 and the central piezoelectric element 1
8 and electrode 15 constitute a first piezoelectric transducer with radius ρ□, and lower electrode 12, piezoelectric elements 18 and 14, and upper electrodes 15 and 16 constitute a second piezoelectric transducer with radius ρ. . In this case, the radius ρ2 of the second piezoelectric transducer is approximately twice the radius ρ of the first piezoelectric transducer, and when driving the first piezoelectric transducer, ultrasonic waves in a high frequency band of 400 MHz are generated. , when driving the second piezoelectric transducer, ultrasonic waves in a low frequency band of 100 MHz are generated. To drive the first and second piezoelectric transducers separately, as shown in FIG.
The lower electrode 1z and the first upper electrode 15 are directly connected to a signal source 17, and the second upper electrode 16 can be selectively connected to the first upper electrode 15 via a switch 18.

Now, the lens length of the acoustic lens 11 is e. Then, the first piezoelectric transformer is generated by turning off the switch 18. Further, when the switch 18 is turned on to drive the second piezoelectric transducer, Therefore, when the switch 18 is turned off, ζ1 is, for example, 400 MHz
If high-frequency ultrasonic waves are generated, switch 1
By turning on 8, low frequency ultrasonic waves of 100 MHz will be generated. In this way, in the ultrasonic microscope of the present invention, the frequency of the generated ultrasonic waves can be changed simply by driving the switch 18 without replacing the ultrasonic head.

The present invention is not limited to the embodiments described above, and numerous modifications and changes are possible. For example, in the example above,
Although the radius ρ2 of the second upper electrode 16 is twice the radius ρ of the first upper electrode 15, it can be set to other values, and of course does not need to be an integer ratio. However, from a practical point of view, it is preferable to set it to 5 times or less, but it is of course possible to set it to 5 times or more. In addition, in the above example, two piezoelectric transducers are configured, but by providing eight or more concentric piezoelectric elements and upper electrodes, eight or more piezoelectric transducers can be provided.
(It is also possible to configure a piezoelectric transducer with 1ffi or more, and in this case, eight or more ultrasonic waves with different frequencies can be selectively generated. Furthermore, in the above-mentioned embodiment, the upper electrode is concentrically shaped. However, the upper electrode and the lower electrode or only the lower electrode can also be made concentric.

Effects of the Invention According to the ultrasonic microscope of the present invention described above, by providing a plurality of concentric piezoelectric elements and an upper electrode, a single ultrasonic head can generate a plurality of ultrasonic waves with different frequencies. This eliminates the troublesome task of replacing the ultrasonic head every time the frequency is changed, allowing rapid observation of the surface and interior of the sample. Furthermore, since there is no need to replace the ultrasound head, ultrasound images of different frequencies can be obtained within the same sound field, allowing more accurate observation. In particular, when the surface position of the sample cannot be clearly determined using low-frequency ultrasound, temporarily generate high-frequency ultrasound to locate the sample surface, then immediately switch to low-frequency ultrasound. This allows for more accurate observation. Furthermore, since the ultrasonic head does not have to be replaced, there is no longer any fluctuation in the influence of the weight of the ultrasonic head or the cable on the vibration device as in the conventional method, which has the advantage of improving scanning accuracy.

[Brief explanation of drawings]

Figure 1 and B are a plan view and cross-sectional view showing the configuration of an ultrasound head used in a conventional ultrasound microscope. Figure 2 shows the lens length of the ultrasound head, the radius of the piezoelectric transducer, and the wavelength of the ultrasound. Graph showing the relationship between sound field intensity and sound field intensity. Figure 8 and B are a plan view and a sectional view showing the configuration of an example of the ultrasound head of the ultrasound microscope of the present invention. 11...Acoustic lens 12...Lower electrode 1fll
, 14... Concentric piezoelectric elements 15, 16...
Concentric upper electrode 17...signal source 18° switch. Patent Applicant Olympus Optical Industry Co., Ltd. Figure 11 1b Figure 2 Procedural Amendment 1. Indication of the case 1982 Patent Application No. 208607 2 Name of the invention Ultrasonic Microscope 3 Person making the amendment Relationship to the case Patent applicant (Oa 7) Olympus Optical Industry Co., Ltd. 7 Contents of the amendment (as attached) ) 1. In lines 5 to 7 of page 5 of the specification, "-111 can be changed in this way" to "-2, in this way, the frequency of the ultrasonic wave can be changed at the same series length l. The same sound field can be obtained by changing the radius ρ of the piezoelectric transducer 5.'' 2, page 6, lines 2 to 4, "These can produce -1111."
It can be formed accurately by patterning using a mask. ” is corrected. 3. Correct page 7, lines 4-17 as follows. [Now, the lens length of the acoustic lens 11 is l. In this case, the first piezoelectric ultrasonic wave can be used by turning off the switch 18. Also, a switch can be used. Therefore, when the switch 18 is turned off, for example, 4
If high frequency ultrasonic waves of 0.00 MHz are used, low frequency ultrasonic waves of 100 MHz can be used by turning on the switch 18. In this way, in the ultrasonic microscope of the present invention, the frequency of the ultrasonic waves used can be changed without changing the sound field by simply driving the switch 18 without replacing the ultrasonic head. ”

Claims (1)

[Claims] 1. One ultrasonic head with a plurality of piezoelectric transducers arranged concentrically on the other end of an acoustic lens whose one end surface is a curved surface with a lens effect, and a plurality of ultrasonic heads with different wavelengths by driving each of these piezoelectric transducers separately. An ultrasound microscope characterized by comprising means for selectively generating sound waves.