JPH0245757A - Ultrasonic probe - Google Patents

Abstract

PURPOSE:To easily make the focus of an ultrasonic wave coincident with the surface of a sample by fixing a 1st and a 2nd visible light source to the ultrasonic probe and making the light from the 1st visible light source and the light from the 2nd visible light source cross each other at the focus. CONSTITUTION:The laser beams 20b and 21b from the laser oscillators 20 and 21 enters optical fibers 22 and 23 and are emitted toward the focus F. The laser beams 20b and 21b, therefore, cross each other at the focus F. When the surface of the sample is at a position (a), the spots of the laser beams 20b and 21b are at a distance from each other and when the sample surface is at a position close to the focus F, the opposite ends of both spots overlap with each other. Then when the sample surface is at a position (c) coincident with the focus F, both spots are put one over the other to become one spot. Thus, the laser beams 20b and 21b of the two laser oscillators 20 and 21 are passed through the optical fibers 22 and 23 to cross each other at the focus F, thereby easily focusing the beams on the sample surface.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an ultrasonic probe used in ultrasonic inspection devices, ultrasonic microscopes, and the like.

[Conventional technology]

Ultrasonic inspection equipment is a device that observes the internal state of an object, such as the presence or absence of defects within the object, without destroying the object.
Furthermore, an ultrasonic microscope is also a device that non-destructively observes the inside of an object and also observes the physical properties of the surface of the object. These devices use ultrasonic probes that emit ultrasonic waves and convert the reflected waves into corresponding electrical signals.

The outline of the ultrasonic microscope will be explained below using figures.

FIG. 3 is a system diagram of a conventional ultrasound microscope.

In the figure, ■ indicates an ultrasonic probe, which is composed of a piezoelectric element 2 and an acoustic lens 3. The piezoelectric element 2 outputs an ultrasonic wave by applying an electric pulse, and converts the reflected wave into an electric signal corresponding to the ultrasonic wave. The acoustic lens 3 has a function of focusing the ultrasonic waves from the piezoelectric element 2 onto one point F. Reference numeral 4 indicates a sample to be inspected, and reference numeral 5 indicates a medium interposed between the acoustic lens 3 and the sample 4. 6, 7.8 are scanning units that drive the ultrasonic probe l in the Y-axis direction (vertical direction with respect to the sample 4), the X-axis direction, and the Y-axis direction, respectively. 9 is a high-frequency pulse generator that generates pulses to be applied to the piezoelectric element 2; 10 is a high-frequency pulse generator that applies pulses from the high-frequency pulse generator 9 to the piezoelectric element 2; however, the signal from the piezoelectric element 2 is not input to the high-frequency pulse generator 9; This is a circulator that does this. Reference numeral 11 denotes an oscilloscope that receives the signal from the piezoelectric element 2 via the circulator 10, and displays the waveform of the received signal. 12 is a gate section that extracts only the waveform of a necessary part (part to be inspected) of the signal from piezoelectric element 2; 13 is a gate section that amplifies and detects the signal taken out by gate section 12, holds its peak value, and outputs it. This is an amplification and detection section. 14 is a scan converter, and the amplification/detection section 1
It also has the function of A/D converting the peak value signal of No. 3 and storing it in the memory corresponding to the coordinate position (X, Y) of the sample 4 at that time, as well as D/A converting these stored values. Reference numeral 15 denotes a display unit that performs a predetermined display based on the values stored in the memory of the scan converter 14. 1
Reference numeral 6 indicates a control unit that controls the operation of such an ultrasonic microscope.

When the pulse output from the high-frequency pulse generator 9 is applied to the piezoelectric element 2 via the circulator 10, the piezoelectric element 2 is excited and outputs ultrasonic waves.

This ultrasonic wave is incident on the sample 4 via the acoustic lens 3 and the medium 5, and its reflected wave returns to the piezoelectric element 2 via the medium 5 and the acoustic lens 3 again. The piezoelectric element 2 converts the reflected wave into an electrical signal proportional to the reflected wave and outputs it to the oscilloscope 11 and the gate section 12.

The oscilloscope 11 displays the electrical signal waveform of the reflected wave with the time axis as the horizontal axis and the size as the vertical axis. On the other hand, the gate section 12, the amplification/detection section 13, and the scan converter 14 process the reflected wave signal output from the piezoelectric element 2, and display only the required signals in an appropriate format on the display section 15. Note that the inspection position on the X-Y plane of the sample 4 is determined by the X-direction scanning section 7.
and can be arbitrarily selected by driving the ultrasound probe 1 with the Y-direction scanning unit 8.

In the above ultrasound microscope, in order to obtain the most precise reflected wave signal from the inspection target area of the sample 4, the focus F of the ultrasonic waves from the ultrasound probe 1 should coincide with the inspection target area. It is clear that

Therefore, before starting the inspection, the position of the ultrasonic probe 1 in the Y-axis direction is first adjusted so that the focal point F coincides with the surface of the sample 4. If the area to be inspected is the surface of the sample 4, the inspection can be started with both of them matching, and if the area to be inspected is the inside of the sample 4, the ultrasound probe should be aligned with it. You can start the test with the camera lowered.

In this way, it is first necessary to align the focal point F with the surface of the sample 4.
This is done by observing the reflected waveform with an oscilloscope 11 while moving it up and down in the axial direction. Figure 4(a), (
b) is a waveform diagram of a reflected wave, in which the horizontal axis represents time and the vertical axis represents the magnitude of the reflected wave. In each figure, A is piezoelectric element 2
is the transmitted wave when transmitting an ultrasonic wave, B is the lens interface wave reflected at the boundary between the acoustic lens 3 and the medium 5, C is the surface wave reflected from the surface of the sample 4, and D is the wave at a certain surface inside the sample 4. Shows reflected interfacial waves. If you move the ultrasonic probe 1 up and down, look at the surface wave C among these waveforms, and set the ultrasonic probe 1 at the position where its magnitude is maximum, this position will be the sample 4.
This is the position where the surface of F coincides with the focal point F. Although the above description is an example of an ultrasonic microscope, it is of course necessary to align the focal point F with the sample surface in an ultrasonic inspection apparatus or the like.

[Problems to be Solved by the Invention] As described above, when the focal point F is made to coincide with the surface of the sample 4, the waveform of the surface wave C is observed with the oscilloscope 11.
If the waveform of the surface wave C is clear as shown in FIG. 4(a), there is no particular problem, although it may be somewhat troublesome to judge the size of the waveform.

However, for example, when the distance between the surface of the sample 4 and the interface is small, the surface wave C and the interface wave overlap and interfere with each other, as shown in FIG. It often occurred that it was difficult to recognize the coincidence of the focal point F and the focal point F.

The purpose of the present invention is to solve the problems in the above-mentioned prior art,
The object of the present invention is to provide an ultrasonic probe that can easily match the focus of ultrasonic waves to the sample surface.

[Means to solve the problem]

In order to achieve the above object, the present invention provides an ultrasonic probe that includes an ultrasonic source and an acoustic lens, and focuses ultrasonic waves emitted from the ultrasonic source to a focal point by the acoustic lens. A visible light source, a second visible light source, and a light guiding means fixed to the ultrasonic probe and causing the light from the first visible light source and the light from the second visible light source to intersect at the focal point. It is characterized by:

[For production]

When aligning the focus of the ultrasonic probe with the sample surface, the first
The visible light source and the second visible light source are caused to emit light, and the light is guided by the light guiding means and projected onto the sample surface. If the focus of the ultrasonic probe and the sample surface do not match, the spots of the respective light beams of the first visible light source and the second visible light source projected onto the sample surface are separated, but the focus and the sample surface do not match. If the surfaces coincide with each other, the above-mentioned spots become one.

By looking at this, it is determined whether the focus and the sample surface match or do not match.

〔Example〕

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 1 is a side view of an ultrasound probe according to an embodiment of the present invention. In the figure, parts that are the same as those shown in FIG. 3 are given the same reference numerals, and explanations thereof will be omitted. 1' indicates the ultrasonic probe of this embodiment. 20.21 is a laser oscillator, 20b, 21b
indicates the laser beam output from the laser oscillator 20.21. 22 and 23 are optical fibers fixed at appropriate locations on the ultrasound probe 1'. The optical fiber 22 inputs the laser beam J, 20b from one end thereof and outputs it from the other end. Similarly, the optical fiber 23 receives the laser beam 2 from one end thereof.
1b is input and output from the other end. Optical fiber 22.2
The central axes (optical axes) of each other end of the lens 3 are made to coincide with the direction of the focal point F, respectively. a, b, and C%d each indicate the assumed position on the sample surface. Incidentally, fl indicates a focal length, and the magnitude of the focal length f is determined by the transport number of the acoustic lens 3, the material of the lens, and the sound speed of the medium 5.

Next, the operation of this embodiment will be explained with reference to the laser beam spot projection diagrams shown in FIGS. 2(a) to 2(d).

Laser beams 20b, 2 from laser oscillators 20.21
1b respectively enter the optical fibers 22 and 23 and are emitted from their tips toward the focal point F.

Therefore, the laser beams 2Qb and 21b once intersect at the focal point F.

Here, when the sample surface is at position a shown by the dashed line in the figure, the laser beams 20)), 21
The spots b are located far apart from each other as shown in Figure 2(a), and if the sample surface is located closer to the focal point, both spots are separated as shown in Figure 2(b). The opposing ends are in an overlapping state. When the sample surface is located at WC to exactly coincide with the focal point F, both spots overlap to form one spot as shown in FIG. 2(C). Moreover, when the sample surface is at a position d further away from the focal point F, both spots are again separated as shown in FIG. 2(d), but in this case, the spot of the laser beam 20b and the spot of the laser beam 21b The spots are opposite to those at positions a and b.

In this way, in this example, the laser beams from the two laser oscillators are passed through optical fibers and crossed at the focal point, so the ultrasonic probe can be moved while observing each spot of the laser beam projected onto the sample surface. It is sufficient to move the ultrasonic probe up and down and stop it at the position where both spots I. overlap, and it is possible to very easily focus the probe on the sample surface, regardless of the waveform of the reflected ultrasonic wave.

Although the above embodiments have been described using a laser oscillator and an optical fiber, a normal light source and lens may also be used. Furthermore, if the light sources used are of different colors, focusing can be performed more easily.

〔Effect of the invention〕

As described above, in the present invention, since the light from two visible light sources is made to intersect at the focal point of the ultrasound, focusing on the sample surface can be easily performed regardless of the ultrasound reflected waveform. can.

[Brief explanation of the drawing]

FIG. 1 is a side view of an ultrasound probe according to an embodiment of the present invention;
Figures 2 (a), (b), (c), and (d) are projection diagrams of laser beam spots; Figure 3 is a system diagram of an ultrasound microscope;
FIGS. 4(a) and 4(b) are waveform diagrams of ultrasonic reflected waves. 1'... Ultrasonic probe, 2... Piezoelectric element, 3... Acoustic lens, 20.21...
-Laser oscillator, 20b, 21b...Laser beam, 22.23...Optical fiber. F...Focus. (C) o, -20b, 21 b

Claims (3)

[Claims] (1) An ultrasonic probe that includes an ultrasonic source and an acoustic lens, and in which the ultrasonic waves emitted from the ultrasonic source are focused by the acoustic lens, including a first visible light source and a second visible light source. and the first
An ultrasonic probe characterized in that it is provided with a light guide means for causing the light from the visible light source and the light from the second visible light source to intersect at the focal point. (2) The ultrasonic probe according to claim (1), wherein the light from the first visible light source and the light from the second visible light source have different colors. (3) In claim (1), the light guiding means includes a first optical fiber that guides the light from the first visible light source and a second optical fiber that guides the light from the second visible light source. An ultrasonic probe characterized by