JPS59176665A - Method and device for measuring partial physical property ofobject - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for producing shifts in phase velocity in an object and relating to the local acoustic impedance of the object. A method of measuring local physical properties of an object, such as layer thickness of the object;
and a support for an object, a signal generator, and an electroacoustic transducer that converts an output signal of the signal generator into a sound wave,
The transducer is capable of conducting sound waves through a medium towards the object under test, producing a shift in the phase velocity in the object and determining the contour and type of inhomogeneity, surface area, etc. associated with the local acoustic impedance of the object. The present invention relates to a device for measuring local physical properties of an object, such as roughness or layer thickness of multilayer objects.

These measurement methods and devices are known.

Conventional methods use a source of sound waves that intermittently conducts sound waves toward an object, and a microphone that serves to receive the reflected sound waves. A signal processing device is coupled to the microphone to interpret the pattern of sound waves reflected by the object. These techniques are very similar to seismic techniques for exploration of natural gas, oil fields, etc.

Application of conventional methods to relatively small scale applications such as medical diagnostics is hampered by the very low resolution. That is, in practice, it is extremely difficult to recognize the narrow and relatively sharp boundary bundles necessary to detect inhomogeneities that are relatively small relative to the wavelength of the acoustic wave.

The present invention aims to increase the resolution of the above measurement method, and in view of the purpose of implementing the above method, the method of measuring the physical properties of the extract of an object according to the present invention uses a steady sound wave. An interference pattern of dense and sparse areas that displays the physical properties contained is formed in the medium by the cooperation of incident and reflected sound waves, and electromagnetic waves are directed on the interference pattern and deflected by the interference pattern. It is characterized by measuring the deflection pattern of electromagnetic waves. In view of the above, the device for measuring local physical properties according to the present invention includes a source of electromagnetic waves, a converter for converting the electromagnetic waves into a signal indicating the intensity of the electromagnetic waves, and an intensity of the electromagnetic waves received based on the signals. The electromagnetic wave generation source is characterized in that it can transmit electromagnetic waves in the direction of the transducer through sound waves that are transmitted in the direction of the object to be inspected and reflected by the object.

It is preferable that the electromagnetic waves be monochromatic in order to obtain a sharp boundary bone with a strong contrast and a deflection pattern. Furthermore, it is advantageous if they are coherent. Concerning the source of electromagnetic waves, it is advantageous to be a laser.

Furthermore, it is preferable to use flat-shaped electromagnetic waves in order to obtain a deflection pattern that is well suited for calculation and interpretation.

The deflection pattern can be evaluated by measuring the intensity of the deflected electromagnetic waves depending on the direction in which they leave an interference pattern. The device for carrying out the above method has the feature that the position of the transducer is adjustable in a direction corresponding to the direction of the incident sound wave.

The deflection pattern can also be evaluated by varying the frequency content of the sound waves and measuring the intensity of the deflected electromagnetic waves which leave an interference pattern in a preselected direction depending on said frequency content. In this case, the frequency content of the signal supplied by the signal generator can be adjusted at will.

Furthermore, the frequency content of the electromagnetic waves emitted by the electromagnetic wave source can be adjusted freely.

To avoid excessive reflections on lower surfaces of relatively thin objects, causing interpretation errors, the frequency content of the sound waves emitted by the electroacoustic transducer must be adjusted to a preselected value within the object under test. Preferably, the depth of penetration is selected so as to be obtained.

On the other hand, the frequency content of the sound waves emitted by the electroacoustic transducer can optionally also be selected in such a way that a substantial difference in the speed of sound in homogeneous and heterogeneous parts of the object to be examined is obtained.

For certain measurements, the intensity of the sound waves emitted by the transducer may need to be relatively high.

In that case, there is a risk that the sound waves reflected by the object will reach the transducer of the above-mentioned intensity and influence the operation of the transducer. In order to avoid this risk, the transducer is characterized in that it conducts the sound waves towards the object and the transducer is arranged in such a way that the sound waves are not reflected by the object or have a negligible effect on the transducer. equipment can be used.

The invention will now be described in detail with reference to a number of optional embodiments and with reference to the accompanying drawings, in which: FIG.

In the drawings, FIG. 1 is a schematic diagram of a first embodiment of the device according to the present invention, FIG. 2 is a schematic diagram similar to FIG. 1 of a second embodiment of the present invention, and FIG. 3 is a schematic diagram of a third embodiment of the device. FIG. 4 is a schematic perspective view of the fourth embodiment, FIG. 5 is a partially fragmented schematic perspective view of the fifth embodiment, and FIG. 6 is a partially fragmented schematic perspective view of the sixth embodiment. Figure 7 shows the ratio IQ/I for a Plexiglas/aluminum layer structure; Figure 8 shows two different vibration frequencies used when immersed in water as a function of the thickness of the Plexiglas layer according to Figure 7. Ratio I for. /I, Figure 9 is a graph showing 32% of the ultrasonic wave projected into the fluid on the anticorrosion layer bonded to the aluminum/%-fuspace.
■Ratios for water and glycerin respectively as a function of v3. /I, is the glass.

FIG. 1 shows a container l containing a fluid 2. FIG.

An object 4 held by a support 3 is provided in this fluid 2 . This object is irradiated with sound waves from above by an electroacoustic transducer 5 connected to the output of the signal generator 6. The signal generator 6 provides an output signal with a preselected frequency to the converter 5. Wavy line 7
1 symbolically shows the sound waves emitted by the electroacoustic transducer 5. These sound waves are flat and directed towards the object 4. A part of the sound wave is reflected by the flat upper surface 8 of the object to be inspected 4, and another part of the sound wave is reflected by the non-uniform object 9.
10. Transmits in the direction of 11. These heterogeneous objects are, for example, foreign objects or air bubbles surrounded by objects. The basis of the measurement method of the present invention is that the speed of sound in a heterogeneous object is different from the speed of sound in a homogeneous part of the object 4. As a result of the difference in the speed of sound, a reflection occurs at the transition surface, and a part of the locally arriving sound wave is reflected and finally appears between the electroacoustic transducer 5 and the flat upper surface 8 of the object 4 Dense and sparse interference patterns are recognized.

A laser 12, which provides coherent, monochromatic electromagnetic radiation, is directed through an aperture 18, a lens 19, and a window 20 into the interference pattern shown at 13 in FIG. This interference pattern 13 operates in such a way that it depends on the nature of the pattern and the wavelength of the incident laser light at which the deflection pattern appears. This deflection pattern, in this case the -order deflection pattern, is evaluated by an array of optical sensors 14 coupled to a signal processing and display device 15 . Photosensor 14 receives electromagnetic radiation through second, larger window 21 and lens 22 .

FIG. 2 shows an embodiment in which the − row of optical sensors 14 is not used, but only one optical sensor 16 is used instead. In this case, a signal generator 1 whose output frequency can be adjusted is used so that the complete deflection pattern of the first order can be evaluated with this configuration.
7 is used.

Because of this power-wavenumber tunability, the electroacoustic transducer 5
can change the wavelength of the sound waves supplied into the fluid. Also, depending on this wavelength, the distance between the dense portion and the sparse portion in the interference pattern 13 also changes.

It is clear that the methods shown in FIG. 1 and FIG. 2 can, in principle, yield the same results. The advantages of the device according to FIG.
The purpose is to determine the results in a short time only by constant measurements using the signal processing and display device 15. In contrast, in the variant embodiment according to FIG. I need time to wake up.

It is also possible to combine both of the above embodiments.

That is, in the embodiment according to FIG. 1, a variable signal generator 17 can also be used instead of the fixed signal generator 6.

Figure 3 shows the ratio of brightness between zero and first-order deflection patterns.
The signal processing display device 2 is used to calculate o/■.
A third embodiment will be shown in which 3 or 3 are suitable.

This embodiment includes two optical sensors 24°2 for zero and primary.
5 are used, and these optical sensors receive electromagnetic radiation through a lens-shaped window 26. Similar to the embodiment of FIG. 1, the use of lenses increases the angular distance of successive orders;
However, the optical sensors 24 and 25 have the advantage of being technically realized and being able to be positioned in relative positions.

The embodiment shown in FIG. 3 has the advantage that the ratio Io/■□ can be measured with higher sensitivity than when only ■ or ■o is measured. This feature will be described later.

FIG. 4 shows a fourth embodiment in which the principle shown in FIG. 3 is further elaborated. The two lasers 27, 28 emit radiation through an aperture 29.30, supplying radiation to a lens 31.32, providing radiation in the guided east form to a slit diaphragm 33.34 and conducted from the slit diaphragm 33.34. Radiation is
Passing through the container 35 with the bottom 36 closed, the concave lens 37
．． 38, and optical sensors 39.40 and 41.42 are arranged behind the lenses 37.38, respectively. Sensors 39, 41 serve to receive the zero order radiation, while sensors 40, 42 serve to receive the first order radiation.

At the upper end of the container 35 an electroacoustic transducer 5 is arranged for supplying ultrasonic waves 7 to the fluid in the container 35.

The bottom 36 of the container is supported by an object 43 containing a foreign object 44 to be examined.

Completely analogous to the arrangement according to FIG.
2 is connected to signal processing means, by which an aerial image of the foreign object 44 can be obtained.

Laser 27. ．． The electromagnetic radiation emitted by 28 is
Note that it extends only a small distance above the top surface of object 43. Although, in principle, similar information exists over long distances of the object, for example, the intensity of the incident sound waves is low, so measurements at short distances as described above are useful. Otherwise, the reflected sound waves do not interfere due to the operation of the transducer 5.

This feature will be explained in more detail with reference to FIG.

Figure 5 is based on the principle shown in Figures 3 and 4,
A device 45 is shown which is particularly suitable for medical diagnostic research.

The device 45 has an electroacoustic transducer 5 arranged at the top end and a bottom section 4.
7 is a container 46 suitable for placement on the skin 48 of a patient 49;
It is equipped with Enclosure 46 is coupled to a light-tight house 50 that is impermeable to radiation having the same wavelength as the electromagnetic radiation emitted by laser 51 . The laser 51 supplies its radiation through a lens 52 toward a slit diaphragm 53;
At a relatively small distance from the bottom 47, a beam of electromagnetic radiation extending horizontally but thin vertically is transmitted through the fluid in the container 46 in the direction of a lens 54 which also serves as a window; As in FIG. 3, two rows of sensors 55.
56 are arranged for the zero and first orders, respectively.

The output signals of the sensors 55 , 56 are fed to a signal processing display device 57 .

FIG. 6 shows a configuration in which the important parts correspond to the configuration shown in FIG. 5, but as a fundamental deviation from that, the fluid container 59 is arranged at an inclined position with respect to the light-shielding house 60. A device 58 is shown. To explain this below, the ray 1f61 supplies a bundle of electromagnetic radiation that spreads horizontally but thins vertically through an aperture 62, a lens 63 and a slit diaphragm 64 in the direction of a cylindrical lens 65. At the rear, two rows of light sensors 66 , 67 are arranged which are coupled to a signal processing and display device 68 .

The container 59 has an axis 69 forming an angle with the plane of the thin bundle of electromagnetic radiation transmitted by the slit diaphragm 64 . As a result of the above-mentioned tilted position, the axis of the reflected electromagnetic radiation flux, indicated schematically by arrow 70 for clarity, has a large area of radiation flux in which the cooperation or interference zone is with the incident part. Since there is a reflection gap and, if necessary, a pattern of dense and sparse areas is generated, an angle is formed with respect to the plane so that it can be calculated as described above.

Due to the tilted position shown in FIG. 6, the reflected flux will not reach the transducer 5 and will never affect its operation. So, using this configuration, the amount of acoustic energy delivered per unit time by the electroacoustic transducer 5 necessarily has to be limited so that high powers can be used, which favorably influences the signal/noise ratio. The electroacoustic transducer is not affected by reflected sound waves.

FIG. 7 shows that for a small change in acoustic impedance, the ratio ■o/■ changes to an abnormally high degree within a certain range. The frequency used in this case is 5MHz
, is.

Figure 8 shows the ratio ■ as a function of the thickness of the Plexiglas layer on the aluminum carrier. /■, is shown.

The horizontal axis corresponds to the micrometer thickness.

The solid line corresponds to the acoustic frequency of 12MH7, the dashed line corresponds to 13,
It is equivalent to 37 MT4z. By carefully selecting the frequency, it is possible to influence the depth of penetration and, related thereto, the focusing of the device.

Figure 9 shows a thickness of 1 supported by an aluminum carrier.
Acoustic impedance for anti-rust layer in mm, □■3
■ As a function of. /■ Indicates the standardized value of □. The acoustic frequency is 5 MHz. The solid curve is valid for water as the permeation medium, and the dashed curve is valid for glycerin.

■The water change in o/1□ is extremely small, and there is almost no or no detectable water change. In glycerin, the change becomes stronger as the value of 32*3 increases. This fact shows that it is necessary to carefully consider the selection of fluid in advance.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of a first embodiment of the device according to the present invention;
FIG. 2 is a schematic explanatory diagram of a second embodiment of the device according to the present invention;
Fig. 3 is a schematic explanatory diagram of the third embodiment, Fig. 4 is a schematic perspective view of the fourth embodiment, Fig. 5 is a partially fragmented schematic perspective view of the fifth embodiment, and Fig. 6 is a schematic perspective view of the sixth embodiment. A partially fragmented schematic perspective view of an example, FIG. 7 shows the ratio ■ for a Plexiglas/aluminum layered structure. Figure 8 shows the ratio for two different frequencies used when immersed in water as a function of the thickness of the Plexiglas layer. Figure 9 shows the ratio Io/Ie for water and glycerin, respectively, as a function of 3□v3 for ultrasonic waves projected onto the fluid on the anticorrosive layer combined with the aluminum half-space. It is a graph. 1,35.46.59... Container, 2... Fluid,
3... Support stand, 4.43... Target object, 5...
・Electroacoustic transducer, 6, 17... Signal generator, 7
... Wavy line, 8... Flat top surface, 9,10.11.
・Heterogeneity, 12.27,28,51.61...Laser, 13...Interference pattern, 14,16,2
4,25°39.40,41,42,55.56. '6
6゜67・・Light sensor, 15.23, 57.68・
・Signal processing display device, 18, 29, 3
0. 62... Aperture, 19.22, 31.32.52°54.63 Lens, 20.26... Window, 2
1...Large second window, 33.34, 53.64
...Slit aperture, 36.47...Bottom, 37
゜38.65...Circle 1 local lens, 44...Foreign substance, 45.58・Device, 48-・Skin, 49
... Patient, 50.60 ... Light House. Patent Applicant: Inofi Namrose Pennotjatsub, Patent Attorney: 1 person

Claims (1)

[Claims] 1. The outline and type of inhomogeneous material that causes a change in the pitch velocity in the object and is related to the local acoustic impedance of the object, the surface roughness or the layer thickness of a multilayer object, etc. A method of measuring the local physical properties of an object uses stationary sound waves, and the cooperation of the incident and reflected sound waves forms an interference pattern of dense and sparse areas in the medium that displays the physical properties involved. . A method for measuring local physical properties, comprising directing electromagnetic waves through the interference pattern and measuring a deflection pattern of the electromagnetic waves deflected by the interference pattern. 2. The method according to claim 1 for measuring the ratio of the intensities of two degrees of deflection; 3. The method according to claim 2 for measuring the ratio of the intensities of zero-order and first-order degrees of deflection. 4. The method according to any of the preceding claims, wherein the electromagnetic waves are monochromatic. 5. The method according to any of the preceding claims, wherein the electromagnetic waves are coherent. 6. The method according to any one of claims miJ, wherein the electromagnetic waves are oblate y-shaped. 7. By measuring the intensity of polarized electromagnetic waves depending on the direction of the electromagnetic wave or leaving an interference pattern. A method according to any of the preceding claims for evaluating a deflection pattern. 8. Evaluating the deflection pattern by measuring the intensity of a deflected electromagnetic wave that changes the frequency content of the sound wave and leaves an interference pattern in a preselected direction depending on said frequency content. Method described in Crab. 9. A method according to any of the preceding claims, wherein the electromagnetic waves are directed in the direction of the interference pattern so as to be as close as possible to the relevant surface. 10, comprising a support for the object, a signal generator, and an electroacoustic transducer that converts the output signal of the signal generator into a sound wave, the transducer being capable of transmitting the sound wave toward the object to be inspected through a medium. , local physical properties of the object, such as the contour and type of inhomogeneities that cause displacements in the phase velocity in the object and are related to the local acoustic impedance of the object, surface roughness or layer thicknesses of multilayer objects. A device for measuring electromagnetic waves, comprising a source of electromagnetic waves, a converter for converting the electromagnetic waves into a signal indicating the intensity of the electromagnetic waves, and a display means for displaying the intensity of the received electromagnetic waves based on the signals, A device for measuring local physical properties, characterized in that the source is capable of transmitting electromagnetic waves in the direction of the transducer through sound waves transmitted in the direction of the object to be examined and reflected by the object. 11 Claim 1 in which the electromagnetic wave generation source is a laser
The device described in item 0. 12. Apparatus according to claims 10 and 11, wherein the position of the transducer is adjustable in a direction corresponding to the direction of the incident sound wave. 13. Apparatus according to any of claims 10 to 12, wherein the frequency content of the signal provided by the signal generator is adjustable. 14. Apparatus according to any one of claims 10 to 12, wherein the frequency content of the electromagnetic waves emitted by the electromagnetic wave source is adjustable. 15. The frequency content of the sound waves emitted by the electroacoustic transducer is selected such that 11 a preselected penetration depth is obtained in the object to be inspected.
16. The frequency content of the sound waves emitted by the electroacoustic transducer according to any of paragraphs 4, 16, is such that the frequency content of the sound waves emitted by the electroacoustic transducer is such that, if necessary, there is a substantial difference in the speed of sound between homogeneous and heterogeneous parts of the object to be inspected. The device according to any one of the selected claims 10 to 15 V), so as to obtain the desired results. 17. The transducer is arranged in such a way that the sound waves are conducted towards the object and no sound waves are reflected by the object, but the effect on the transducer is negligible. Apparatus according to any of paragraph 16. 18. Claim 1, further comprising means for positioning the object relative to the path of the electromagnetic waves so that the electromagnetic waves are directed as close as possible to the relevant surface of the object and towards the interference pattern.
Any one of Items O to 17 (device described in ζ).