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BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a conventional focusing method, FIG. 2
shows a conventional focusing method, and FIG. 3 shows an embodiment of the present
invention. 4 and 5-6 and 7 show another embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION The present invention is the focusing of acoustic
waves in the ultra high frequency range. It relates to the device. In recent years, the generation of
ultra-high frequency sound waves ranging up to 1 uHz. As a result, it has become possible to
obtain an acoustic wavelength of about 1 micron in water and thus to suggest the possibility of
obtaining high resolution ultrasonic heat. For such development, in the range of IMHz to IOMHz.
It is highly desirable to apply the various established techniques to this frequency range. (1) The
ultrasonic focusing method using an acoustic lens or a curved electroacoustic transducer having
a predetermined focal point has already been established in a high frequency region and applied
to various ultrasonic imaging devices. The application of this focusing technique to the ultra high
frequency range is conventionally performed as a natural extension of the high frequency range
technology. As shown in FIG. 1, the RF electric signal applied from the RF signal source 10 to the
electroacoustic transducer 12 generates an ultrasonic wave in the propagation charge 14. This
sound beam 20 is sent to a tt wave lens 16 made on the end face of the propagation medium 14,
which is effective with the focusing medium 18. Form a concave shape, so the acoustic beam is at
focus F. Focused. Here, a zinc oxide piezoelectric thin film is commonly used as the
electroacoustic transducer, sapphire is used as a propagation medium, and water is used as a
focusing medium. FIG. 2 shows another prior art example. In part, it is a curved surface 34
formed on the substrate 32 and having a predetermined focal point. The curved piezoelectric
vibrator 38 is formed, and by applying an RF electric signal from the RF signal source 10,
ultrasonic waves are directly emitted to the focusing medium 36 and focused on the focal point F
(2). In any case, the collection distance and the opening are to keep the focusing effect with a
small total number. Ratio is close to one. With a sample placed at the focal point using such
focused sound waves. Information reflecting the elastic properties of the sample by generating
reflected and transmitted sound waves and detecting these ultrasonic signals 1 'f! : I do not know.
However, in such a configuration, 1-. Compared with the case of the high frequency region of 10
MHz, 1 (in the extremely high frequency region of i Hz, there is an essential need). It is a hand
where in the ultra-high frequency region there is a neat damping effect in the focusing medium.
For example, focusing g'Ii! In the case of water, which is frequently used, D at 1 is 1.7 × 10 −
sdll / 諺 while 11 j Hz is the actual [166 dB. There is an attenuation of 7 wm. Moreover, it is
known that this attenuation increases in proportion to the two ends of the frequency when the
frequency is opened in history.
The above-mentioned circumstances in the frequency domain result in the limitation that the
focus distance can not be taken too large. As is well known [in order to design an excellent lens
with a small F number, it is necessary to make the aperture and the focus-(8) distance equal, so
the above situation is to make a lens with an extremely small aperture. Look for In the past,
efforts have been made to research on micro lens formation technology for the reasons described
above. In order to avoid the attenuating effect from being attenuated by 166 dH7 at I GHz in
water, a value group lens such as 0.1 * is needed, like this. Processing must be said to be an
extremely difficult task. The present invention has been made in view of the above-mentioned
problems t--in that the acoustically low-loss medium "jit" is produced between the lens and the
focusing medium without impairing the focusing effect. Wearable damping effect in the ultra
high frequency range. をさけようとするものである。 That is, fruit bundle sound limb B The
beam is directed to the sample as it forms. The effective area is a very narrow part near the infocus area, and a path from the lens surface to the in-focus area to create a collection beam, and
a propagation path for focusing 1) is overwhelmingly larger, and it is notable that the loss and
loss in this Perth are huge, and that this path is replaced with an acoustic low-loss material,
which is remarkable (4) Try to compensate for the loss. For example, considering the aperture as
a sapphire-water lens system model with an aperture of 0.5 and a focal distance of 0.5, ultrasonic
wave. Since the above-mentioned path is 0.5 m while the focus area is about 1 micron in
mantissa IJ Hz, it can be seen that this part attenuates by as much as 63 dB. Therefore, The effect
of replacing this portion with a low loss material is extremely large. In this case, as the entry
prize, the sound speed is in the middle between the lens material and the speed of the medium so
that the acoustic loss is low and the lens action and the habit are not used. That's great. FIG. 3
shows one example of this study. In particular, the lens material 44 (eg, sapphire (11000 m / Sl,
bath fused quartz + 5970 m / Sl, quartz + 5700 m / Sl,...) According to the BF electricity applied
to the electroacoustic transducer 42 from the 托 F signal source 10. It generates around 1f afia
on MgO + 5000m / 81 etc.). This common wave is formed on the lens 50 formed of the curved
surface 46 made of the lens material and the lens N'-48.
する。 It is a low-loss insertion item that is the gist of the present invention. In particular,
mercury and potassium, which are all liquid electrodes at normal temperature, were used. In the
conventional configuration, the difference between the velocity of sound of the lens material and
the velocity of the medium water (1500 m / sl plays a role of the lens action, but mercury + 1450
m / sl, potassium (28701 n / s l It is clear that such storage space does not have any influence on
the lens action later than the light velocity of the material. By such low loss material users, the
loss in the focusing channel is about 7 dB for mercury at about 25 dkl X Ga, in the case of the
above-mentioned aperture 1 focal length, 0.5 + w model lens for focusing distance. It can be seen
that the loss compensation is 57 dB and 76 dB compared to, and the effect of 7 is great. As a
result, in the case of Honmochi, remarkable loss compensation became flexible without loss of
lens effect fx. As shown in FIG. 4, a thin film 72 (several microns) of Mylar may be sandwiched
between the liquid gold crucible 70 and the water 74 to prevent mixing. Mylar has a speed of
sound of +1,700. (6) m / s), and since the light component is thin, the influence on the focusing
action can be almost ignored. The low-loss human substance may be solid. If the metal of the lens
material is slower than the sound velocity, the attenuation of the metal is generally much smaller
than that of water, so that the purpose of the present invention can be achieved. However, if it is
left as a solid, it is necessary first to process a convex surface and the processing is severe, and
secondly, the method of bonding to a lens material is not advantageous from black ink which is
difficult in the ultrahigh frequency region. The Ministry of the present invention et al. Melts a
metal having a melting point lower than the heat resistance temperature of the lens material
(melting point, for example, 1477 tZ 'in the case of quartz) and pours it onto the lens surface, and
then solidifies to form the composition of this tea. It was dusty. In this case, it is clear that if the
melting point is lower than that of the lens material and the speed of sound is slower than that of
the lens material, a sharp gold tip will be good. The person who made the proposal is Indium
(sound speed is 250 Orll / S,). Melting point 156 C), tin (sound velocity 3320 m / S). Melting
point is 231 Ul, lead (sound velocity is 1960 m / s, melting point is 327 C), @ (f speed is 365 QIn
/ S, melting point). As for (7), good results were obtained using 9611 Z '1 and the like. For
example, in the case of silver (27 dB / −, $ 1 (j) IZlt [Ite, 1e model 1), it has become possible to
obtain a loss compensation of 13 dB, that is, 70-dB. FIG. 5 is another embodiment of the present
F! 1) Apply itF electricity 1g to the electroacoustic transducer 64 from the RF source 10. Here,
since the conversion element 64 itself has a concave shape for focusing, the generated super
high frequency sound wave is directly emitted to the low loss soda material 66 and forms a
focused ultrasonic beam at the focal point F in the g1M water 68 Do. According to the people of
low loss material already mentioned. The effect of the loss compensation is exactly as described
in the previous example. . Reference numeral 62 denotes a lens material. FIG. 6 is another
embodiment of the present invention. With both end faces. The piezoelectric thin film 110 (zinc
oxide, lithium niobate, sulfur) on one end face of the optically polished crystal 120 (sapphire,
fused quartz, magnesium oxide, quartz, etc.). (Cadmium fluoride etc.) is applied to it and RFi [Gi
signal is applied to generate plane acoustic wave. One end face made of a crystal such as
sapphire is concave and the other end face 142 is flat. (8) A concave plate as a plate, the surface
lens system 140 and the crystal 120 are brought into close contact with each other, and a
mercury or potassium temple solution in the concave interval. Body metal 130 t 1-Light loading.
Sapphire and the like have a sound velocity of about 10000 m / s, and mercury (1500 m / 81
'potassium [2870 m / Sl, so it is clear that this convex boundary is a positive lens. If the length of
the convex lens system is set slightly shorter than the focusing distance of this positive lens, the
plane acoustic wave propagating in the crystal is focused by this positive lens in the crystal 140
and focused near the WN surface 142. Become parallel beams. Therefore, if the focal point is
prepared as described above, there is no ink that is refracted to the medium 150 (water etc.). The
S that the focused beam will propagate is obvious. With such a configuration, it is possible to
largely compensate for the large loss which is mostly a crystal with little acoustic loss and which
is stuck with the conventional example. ■ As can be understood from the shape, this convex lens
may be relatively large, and the polishing technology developed by optics. Is available. ■ Other
lenses freely lens alone. Has the advantage of being able to replace yarn, etc., (9)? -It greatly
contributes to the sound wave focusing technology in the super high frequency domain such as a
sound wave microscope. FIG. 7 shows another embodiment of the present invention. A crystal
such as sapphire or the like having a flat end face 242 and a concave end face 230 on the lens
thread 240, a field of view complementary to the end face 230, and a flat crystal 220 at the other
end face. To produce the piezoelectric thin film 210, and use the crystal 220 which is slower
than the distortion of the crystal 240. いるものである。
In such a configuration, it will be easily understood that the interface 230 is a lens of a positive
lens and produces the same effect as the above ic crop. The inventors of the present invention
use a method of pouring a molten glass into a concave surface 9111 of a lens thread 240 °
made of sapphire, cooling it and then polishing this surface to form the piezoelectric thin film
210, and the interface Unwanted contact at 230 was generated. In all of the above embodiments,
only for the transmission yarn. It has been stated that it is clear that it can be applied to the
receiving yarn as it is. らかであろう。 Also, both transmit lens and receive lens. Being able to use
as a transmitting and receiving lens if placed at the focal point-,. Of course αO is. As described
above, according to the present invention, it is possible to greatly reduce the artifical loss in the
focusing propagation path of the ultrasonic wave in the ultra-high frequency region, and to focus
the focused sound beam of much larger power than before. The contribution to devices that
make it possible to apply to a sample and that utilizes an extremely narrow focused sound beam
in the ultra high frequency region is extremely large, and the effect on industrial production is