JP2021081361A - Laser beam reception device for reception, laser ultrasonic wave measurement device, and method for measuring laser ultrasonic wave - Google Patents

Abstract

To allow a reception of a sufficient amount of reflected light even when an optical probe is not facing a measurement target.SOLUTION: A laser beam reception device 10 for reception includes: a laser beam reception unit 12 for reception for receiving a laser beam from a measurement target; and a first light collecting mirror 15 for collecting a laser beam to the laser beam reception unit 12 for reception. The first light collecting mirror 15 is an aspherical rotational body, and the laser beam reception unit 12 for reception is arranged between a focal point 15f of the first light collecting mirror 15 and the first light collecting mirror 15 on a center line 15c of the first light collecting mirror 15.SELECTED DRAWING: Figure 1

Description

Embodiments of the present invention relate to a receiving laser beam receiver, a laser ultrasonic measuring device, and a laser ultrasonic measuring method.

Ultrasonic testing (UT) is a technology that can confirm the soundness of the surface and inside of structural materials in a non-destructive manner, and is an indispensable inspection technology in various fields.

Arbitrary by arranging contact-type UTs that transmit and receive ultrasonic waves by bringing the piezoelectric elements into contact with the inspection target, and arranging small piezoelectric elements for ultrasonic transmission and reception, and shifting the timing (delay time) for each piezoelectric element to transmit ultrasonic waves. Phased array ultrasonic flaw detection tests (PAUTs) that can form waveforms are widely used in industrial applications. Further, a method such as laser ultrasonic method (LUT: Laser Ultrasonic Testing) in which ultrasonic waves are excited by irradiation with a pulsed laser and minute vibrations on the surface to be inspected are measured by another laser and a laser interferometer is also used. Since the laser ultrasonic method can be inspected without contact, it is also applied to inspection during welding work.

Various forms have been proposed for ultrasonic signal processing methods and devices and methods for visualizing the inside of an inspection target according to the application. For example, when visualizing the inside of a living body by ultrasonic waves, the inside of the living body is visualized. Since the speed of sound differs depending on the structure, a method of measuring ultrasonic waves assuming the speed of sound in a specific area to be inspected and analyzing from the difference between the obtained detection result and the expected result, etc. Has also been proposed.

Japanese Patent No. 5651533 Japanese Patent No. 4632517 Japanese Patent No. 5528083

When inspecting a defect in a measurement target by laser ultrasonic measurement, the vibration of the surface of the measurement target is measured using a received laser beam and an interferometer to obtain an ultrasonic waveform. That is, it is necessary to irradiate the surface of the measurement target with the received laser light using an optical probe and receive the reflected light. At this time, the amount of reflected light required for measurement can be obtained by making the irradiation direction of the received laser light perpendicular to the contact surface of the received laser light irradiation portion on the measurement target.

Therefore, when performing laser ultrasonic measurement, it is necessary to adjust the irradiation direction of the received laser beam each time the measurement is performed, which causes a problem that the adjustment mechanism becomes complicated and the adjustment takes time.

When the state in which the receiving optical probe faces the measurement target in the state of facing the direction perpendicular to the contact surface at the receiving laser beam irradiation point on the measurement target, the state in which the optical probe does not face the measurement target. Then, it is necessary to solve the problem that the amount of reflected light required for measurement cannot be obtained.

Therefore, an object of the embodiment of the present invention is to make it possible to receive a sufficient amount of reflected light even when the optical probe does not face the measurement target.

In order to achieve the above object, the receiving laser light receiving device according to the present embodiment has a receiving laser light receiving unit that receives the laser light from the measurement target and a laser light toward the receiving laser light receiving unit. The first condensing mirror is an aspherical rotating body, and the receiving laser light receiving unit is on the central axis of the first condensing mirror and said. It is characterized in that it is arranged between the focal point of the first focusing mirror and the first focusing mirror.

Further, the laser ultrasonic measuring device according to the present embodiment is characterized by including an ultrasonic generating device for exciting ultrasonic waves on the measurement target and the above-mentioned receiving laser light receiving device.

Further, in the laser ultrasonic measurement method according to the present embodiment, for the measurement of the measurement target, an installation step of installing an ultrasonic generator and a laser light receiver for reception, and an ultrasonic wave generated by the ultrasonic generator as an inspection target. The ultrasonic generation step for generating the measurement target, the reception laser light irradiation step for irradiating the measurement point of the measurement target with the reception laser light, and the first focusing of the reflected laser light from the irradiated portion of the measurement target. It is characterized by having a condensing step of condensing with a mirror and a light receiving step of receiving the reflected laser light condensed by the condensing mirror with a receiving laser light receiving unit.

It is a vertical cross-sectional view which shows the structure of the receiving laser beam receiving apparatus which concerns on 1st Embodiment. It is a vertical cross-sectional view which conceptually shows 1st example of the operation of the receiving laser beam receiving apparatus which concerns on 1st Embodiment. It is a vertical cross-sectional view which conceptually shows the 2nd example of the operation of the receiving laser beam receiving apparatus which concerns on 1st Embodiment. It is a block diagram which shows the structure of the laser ultrasonic measuring apparatus which concerns on 1st Embodiment. It is a block diagram which shows the structure of the modification of the laser ultrasonic measuring apparatus which concerns on 1st Embodiment. It is a flow figure which shows the procedure of the laser ultrasonic measurement method which concerns on 1st Embodiment. It is a vertical cross-sectional view which conceptually shows the structure of the receiving laser beam receiving apparatus which concerns on 2nd Embodiment. It is a vertical cross-sectional view which conceptually shows the structure of the receiving laser beam receiving apparatus which concerns on 3rd Embodiment. It is a conceptual perspective view which shows 1st example of the method of changing the position of the receiving laser light irradiation part by the laser ultrasonic measuring apparatus which concerns on 3rd Embodiment. It is a conceptual perspective view which shows the 2nd example of the method of changing the position of the receiving laser light irradiation part by the laser ultrasonic measuring apparatus which concerns on 3rd Embodiment.

Hereinafter, a laser light receiving device for receiving, a laser ultrasonic measuring device, and a laser ultrasonic measuring method according to an embodiment of the present invention will be described with reference to the drawings. Here, the parts that are the same as or similar to each other are designated by a common reference numeral, and the description of superimposition will be omitted.

[First Embodiment]
FIG. 1 is a vertical cross-sectional view showing the configuration of a receiving laser beam receiving device according to the first embodiment.

The receiving laser light receiving device 10 acquires information on an ultrasonic reflection source 1d such as a defect in the measurement target 1 included in the ultrasonic waves propagating in the measurement target 1 in the laser ultrasonic measurement device 100 (FIG. 4). Therefore, it is configured for the purpose of receiving the reflected laser light on the surface of the measurement target 1 of the reception laser light irradiating the measurement target 1.

As shown in FIG. 1, the receiving laser beam receiving device 10 includes a receiving laser beam receiving unit 12 and a first condensing mirror 15.

The receiving laser beam receiving unit 12 receives the reflected laser beam on the surface of the measurement target 1. In the configuration shown in FIG. 1, a receiving laser light irradiating unit 11a for irradiating the measurement target 1 with the receiving laser light is provided, and is provided integrally with the receiving laser light receiving unit 12.

Here, the laser used by the receiving laser light irradiation unit 11a includes, for example, Nd: YAG laser, CO2 laser, Er: YAG laser, titanium sapphire laser, Alexandrite laser, ruby laser, dye (die) laser, and excimer laser. Can be used. The laser light source is either a continuous wave or a pulse wave, and may be composed of not only one but also two or more laser light sources.

An optical fiber 13 for extracting the reflected laser light received from the receiving laser beam receiving unit 12 is provided and penetrates the first condensing mirror 15. The optical fiber 13 may pass through the inner surface side of the first condensing mirror 15 without penetrating the first condensing mirror 15.

The main body 15a of the first condensing mirror 15 is an aspherical rotating body such as a rotating elliptical body, and its shape is rotationally symmetric with respect to the center line 15c. A mirror surface portion 15b is provided on the concave surface side, that is, the inner surface side of the first condensing mirror 15. The mirror surface portion 15b may be formed by finishing the surface of the main body portion 15a to a mirror surface, or may be provided on the surface of the main body portion 15a by vapor deposition or the like. It is generally desirable that the reflectance of the mirror surface portion 15b of the first condensing mirror 15 is high, but it is also possible to adjust the reflectance and the distribution of the condensed light by changing the surface roughness. It may be adjusted as described above.

The first focusing mirror 15 has a focal point 15f in which a light beam parallel to the center line 15c is connected to one point.

The receiving laser light receiving unit 12 is arranged on the center line 15c of the first condensing mirror 15 and between the focal point 15f of the first condensing mirror 15 and the first condensing mirror 15, and is a mirror surface portion. It is arranged so as to face 15b. On the other hand, the receiving laser light irradiating unit 11a is arranged in the opposite direction to the receiving laser light receiving unit 12, that is, on the side facing the measurement target 1.

FIG. 2 is a vertical cross-sectional view conceptually showing a first example of the operation of the receiving laser beam receiving device according to the first embodiment. FIG. 2 shows a case where the receiving laser beam receiving device 10 faces the receiving laser beam irradiating unit 1a.

In this case, even when the first condensing mirror 15 is not provided as in the conventional case, the light 2 reflected from the irradiation unit reaches the position P where the light receiving unit 12 for receiving laser light is provided. However, in the present embodiment, the reception laser light at the position P is obtained by condensing a part of the irradiation unit reflected light 2 scattered by the reception laser light irradiation unit 1a on the measurement target 1 as the mirror surface reflected light 3. The amount of light received by the light receiving unit 12 reflected from the irradiation unit 2 can be increased.

FIG. 3 is a vertical cross-sectional view conceptually showing a second example of the operation of the receiving laser beam receiving device according to the first embodiment. FIG. 3 shows a case where the receiving laser beam receiving device 10 is not directly facing the receiving laser beam irradiating unit 1a.

In this case, when the first condensing mirror 15 is not provided as in the conventional case, the amount of received light is reduced by the amount not facing each other. On the other hand, in the present embodiment, a part of the irradiation unit reflected light 2 scattered by the reception laser light irradiation unit 1a on the measurement target 1 is condensed as the mirror surface reflected light 3 for reception at the position P. The amount of light received by the irradiation unit reflected light 2 by the laser light receiving unit 12 can be increased.

As described above, the receiving laser light receiving device 10 according to the present embodiment condenses a part of the scattered irradiation unit reflected light 2 as specular reflected light 3 so as to face the receiving laser light irradiation unit 1a. It is possible to measure ultrasonic light without using an adjustment mechanism for this purpose.

FIG. 4 is a block diagram showing a configuration of a laser ultrasonic measuring apparatus according to the first embodiment.

The laser ultrasonic measuring device 100 includes an ultrasonic wave generator 50, a receiving laser beam receiving device 10, and a light receiving mechanism 30.

In the present embodiment, the case where the ultrasonic wave generation method is a contact type is shown, and the ultrasonic wave generation unit 50 includes an ultrasonic wave generation unit 51 such as a piezoelectric element or an ultrasonic array probe. The piezoelectric element has a configuration consisting of a mechanism for generating ultrasonic waves, a damping material for damping the ultrasonic waves, and a front plate attached to the oscillation surface of the ultrasonic waves, or a combination thereof.

The receiving laser light receiving device 10 of the present embodiment receives from the receiving laser light source 11 to the receiving laser light irradiating unit 1a of the measurement target 1 together with the receiving laser light receiving unit 12 that receives the reflected laser light of the irradiating unit. It also has a receiving laser beam irradiation unit 11a that irradiates the laser beam for reception.

The light receiving mechanism 30 includes an interferometer 31, a signal processing recording unit 32, and an image display unit 33. The interferometer 31 measures the Doppler shift of the received laser reflected light. The signal processing recording unit 32 records the measured ultrasonic waveform after performing signal processing such as aperture synthesis processing, averaging processing, moving average, filter, FFT, and wavelet transform. The image display unit 33 displays this result as an image.

The operation of the laser ultrasonic measuring apparatus 100 having the above configuration will be described.

The incident ultrasonic wave incident on the measurement target 1 by the ultrasonic wave generating unit 50 is reflected by the ultrasonic reflection source 1d such as a defect existing inside the measurement target 1, and reaches the surface of the measurement target 1. As a result, the ultrasonic waves generate minute vibrations on the surface of the measurement target 1.

The receiving laser light irradiating unit 1a on the surface of the measurement target 1 is irradiated with the receiving laser light from the receiving laser light irradiating unit 11a. The irradiation unit reflected light 2 reflected by the reception laser light irradiation unit 1a from the reception laser light enters the reception laser light reception device 10.

In the receiving laser light receiving device 10, as described with reference to FIGS. 1 to 3, a part of the irradiation unit reflected light 2 scattered by the receiving laser light irradiation unit 1a on the measurement target 1 is collected as the mirror surface reflected light 3. By illuminating, the amount of light received by the irradiation unit reflected light 2 by the reception laser light receiving unit 12 at the position P can be increased.

The laser light received by the receiving laser beam light receiving unit 12 is sent to the light receiving mechanism 30, undergoes interference measurement by the interferometer 31, signal processing by the signal processing recording unit 32, and is displayed by the image display unit 33.

FIG. 5 is a block diagram showing a configuration of a modified example of the laser ultrasonic measuring apparatus according to the first embodiment. This modification shows a non-contact type for generating ultrasonic waves, and the ultrasonic wave generator 50 further includes a laser irradiation device 60 for ultrasonic excitation.

The ultrasonic excitation laser irradiation device 60 of the ultrasonic generator 50 includes a laser light source 61 and an optical mirror 62. The laser beam for excitation from the laser light source 61 is turned around by an optical mirror 62 or the like as necessary, reaches the ultrasonic wave generating unit 51, excites the ultrasonic wave generating unit 51, and generates ultrasonic waves. In other respects, it is the same as the case shown in FIG.

FIG. 6 is a flow diagram showing the procedure of the laser ultrasonic measurement method according to the first embodiment.

First, the ultrasonic wave generator 50 and the receiving laser beam receiving device 10 are installed for the measurement of the measurement target 1 (step S01).

Next, the ultrasonic wave generator 50 generates ultrasonic waves in the measurement target 1 (step S02).

Next, the receiving laser beam irradiation unit 11a irradiates the measurement point of the measurement target 1 with the receiving laser beam (step S03).

The reflected laser light 2 reflected by the receiving laser light irradiating unit 1a is condensed as the specular reflected light 3 by the first focusing mirror 15 (step S04). The receiving laser beam light receiving unit 12 receives the condensed reflected laser light 2 (step S05).

As described above, according to the present embodiment, a sufficient amount of reflected light can be received even when the optical probe does not face the measurement target.

[Second Embodiment]
FIG. 7 is a vertical cross-sectional view conceptually showing the configuration of the receiving laser beam receiving device according to the second embodiment.

The receiving laser beam receiving device 10 according to the second embodiment has a second focusing mirror 16 in addition to the first focusing mirror 15. The shape of the second focusing mirror 16 is also an aspherical rotating body.

The second condensing mirror 16 is arranged at a position where the specular reflection laser beam 3 condensed by the first condensing mirror 15 is condensed.

Further, the receiving laser beam receiving unit 12 receives the specular reflection laser beam focused by the second focusing mirror 16. Therefore, the receiving laser beam receiving unit 12 is arranged at a position closer to the second focusing mirror 16 than the focal length of the second focusing mirror 16.

The distribution of the irradiated portion reflected light 2 when the received laser reflected light is reflected by the irradiation portion 1a on the surface of the measurement target 1 is affected by the surface state of the measurement target 1. Here, when the surface of the measurement target 1 is close to a mirror surface, the distribution of the received laser reflected light is concentrated in the direction of the reflected angle of the same angle with respect to the incident angle of the received laser irradiation light. On the other hand, when the surface is rough, the received laser reflected light is more likely to be scattered and has a wide distribution.

In such a case, the first condensing mirror 15 widely receives the irradiation portion reflected laser light 2 reflected on the rough surface and reflects it toward the second condensing mirror 16. The second condensing mirror 16 transmits the laser light to the receiving laser beam receiving unit 12, so that the condensing amount can be secured.

[Third Embodiment]
FIG. 8 is a vertical cross-sectional view conceptually showing the configuration of the receiving laser beam receiving device according to the third embodiment.

This embodiment is a modification of the first embodiment, in which the receiving laser light irradiating unit 11a is configured separately from the receiving laser light receiving unit 12, and the receiving laser light irradiating unit 11a is placed separately. ing. Other than that, it is the same as that of the first embodiment.

Generally, in the case of a configuration in which the irradiation portion and the light receiving portion of the receiving optical probe are integrated as in the first embodiment, it is necessary to split the irradiation light and the reflected light inside the probe by using an optical element such as a beam splitter. There is. Therefore, a part of the laser emitted from the receiving laser light source is used as the irradiation light, whereas in the case of a separate configuration, all the received laser light can be used as the irradiation light.

Further, since the receiving laser light irradiating unit 11a is placed separately from the receiving laser light receiving unit 12, the position of the receiving laser light irradiating unit 1a of the measurement target 1 is changed by an optical or mechanical method. It becomes possible. Even in this case, the amount of collected reflected laser light can be secured by the configuration including the first focusing mirror 15.

FIG. 9 is a conceptual perspective view showing a first example of a method of changing the position of a receiving laser beam irradiation unit by a laser ultrasonic measuring apparatus according to a third embodiment. In this example, the galvano scanner 18 is used, and the position of the receiving laser beam irradiation unit 1a can be changed at high speed by a system that drives the mirror at high speed like the galvano scanner 18.

FIG. 10 is a conceptual perspective view showing a second example of a method of changing the position of the receiving laser beam irradiation unit by the laser ultrasonic measuring apparatus according to the third embodiment. In this example, the drive stage 19 drives and scans the receiving laser beam irradiation unit 11a.

As in the examples of FIGS. 9 and 10, the merit that the receiving laser light irradiating unit 11a is separate from the receiving laser light receiving unit 12 can be utilized.

In addition, since not only the transmitting point but also the receiving point can be moved at high speed and sufficient light can be collected by the condensing mirror, in-process inspection of a high-temperature object to be measured such as a welded structure or a laminated molded product during manufacturing It is possible to perform more robust non-contact measurement by reducing restrictions on the shape of the object to be measured and the required measurement range.

[Other Embodiments]
Although the embodiments of the present invention have been described above, the embodiments are presented as examples and are not intended to limit the scope of the invention.

Moreover, you may combine the features of each embodiment. In addition, the embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention.

The embodiments and variations thereof are included in the scope of the invention described in the claims and the equivalent scope thereof, as are included in the scope and gist of the invention.

1 ... Measurement target, 1a ... Receiving laser light irradiating unit, 1d ... Ultrasonic reflecting source, 2 ... Irradiating part reflected light, 3 ... Mirror surface reflected light, 10 ... Receiving laser light receiving device, 11 ... Receiving laser light source, 11a ... Receiving laser light irradiating unit, 12 ... Receiving laser light receiving unit, 13 ... Optical fiber, 15 ... First condensing mirror, 15a ... Main body, 15b ... Mirror surface, 15c ... Center line, 15f ... Focus, 15p ... innermost point, 16 ... second condensing mirror, 18 ... galvano scanner, 19 ... drive unit, 20 ... reception laser irradiation unit, 21 ... irradiation head, 22 ... optical fiber, 30 ... light receiving mechanism, 31 ... Interferometer, 32 ... Signal processing recording unit, 33 ... Image display unit, 50 ... Ultrasonic generator, 60 ... Laser irradiation device for ultrasonic excitation, 61 ... Laser light source, 62 ... Optical mirror, 100 ... Laser ultrasonic measuring device

Claims (10)

A receiving laser beam receiver that receives the laser beam from the measurement target,
A first condensing mirror that condenses laser light toward the receiving laser beam receiving unit,
Equipped with
The first condensing mirror is an aspherical rotating body, and the receiving laser light receiving unit is on the center line of the first condensing mirror, and the focal point of the first condensing mirror and the first condensing mirror. Arranged in between,
A laser beam receiver for reception, characterized in that. The receiving laser light receiving device according to claim 1, further comprising a receiving laser light irradiating unit that irradiates a measurement target with a receiving laser light. The receiving laser light receiving device according to claim 2, wherein the receiving laser light receiving unit is integrally formed with the receiving laser light irradiating unit. The distance between the focal point of the first focusing mirror and the irradiation portion of the receiving laser light in the measurement target is the farthest point from the irradiation portion of the receiving laser light in the first focusing mirror and the receiving laser. The receiving laser light receiving device according to claim 2 or 3, wherein the distance is shorter than the distance to the light-irradiating portion. The receiving laser light receiving device according to claim 2 to 4, further comprising an optical mechanism or a driving mechanism for operating the receiving laser irradiation light emitted from the receiving laser light irradiation unit. The first condensing mirror that condenses the laser light from the measurement target,
A second condensing mirror that further condenses the laser light focused by the first condensing mirror,
A receiving laser beam receiving unit that receives the laser beam focused by the second focusing mirror, and a receiving laser beam receiving unit.
Equipped with
The first condensing mirror and the second condensing mirror are each an aspherical rotating body, and the receiving laser light receiving unit is located closer to the second condensing mirror than the focal length of the second condensing mirror. Arranged,
A laser beam receiver for reception, characterized in that. An interferometer for interferometrically measuring the laser light received by the receiving laser beam receiver,
A signal processing recording unit for recording and analyzing ultrasonic signals measured by a receiving optical probe interferometer,
An image display unit that displays the inspection results as a two-dimensional or three-dimensional image from the ultrasonic waveform analyzed by the data recording means,
The receiving laser beam receiving device according to any one of claims 1 to 6, further comprising. An ultrasonic generator for exciting ultrasonic waves on the measurement target,
The receiving laser beam receiving device according to any one of claims 1 to 7.
A laser ultrasonic measuring device characterized by being equipped with. Installation steps to install an ultrasonic generator and a laser beam receiver for reception for measurement of the measurement target, and
An ultrasonic wave generation step in which the ultrasonic wave generator generates ultrasonic waves to the measurement target, and
A receiving laser beam irradiation step of irradiating the measurement point to be measured with a receiving laser beam,
The first condensing step of condensing the reflected laser light from the irradiated portion of the measurement target with the first condensing mirror, and
A light receiving step in which the receiving laser light receiving unit receives the reflected laser light collected by the condensing mirror, and
A laser ultrasonic measuring method characterized by having. After the first focusing step and before the light receiving step, a second focusing step is performed in which the reflected laser light focused in the first focusing step is further focused by the second focusing mirror. The laser ultrasonic measurement method according to claim 8, further comprising.

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