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JPS6358154

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DESCRIPTION JPS6358154
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
apparatus for generating ultrasonic waves in a noncontacting manner on a test material and is
used, for example, for nondestructive testing of internal defects in the test material using
ultrasonic waves. Ru. [Prior Art] It is possible to generate focused ultrasonic waves in a
noncontact manner on an object by instantaneously irradiating an energy beam such as a laser
beam on the surface of the object that absorbs light, and to use this for nondestructive
inspection. No. 53-134488. FIG. 5 is a schematic view showing the structure of the ultrasonic
wave generator disclosed in the Japanese Patent Application Laid-Open No. 53-134488. In FIG.
5, for example, an internal defect should be inspected, that is, an object to be ultrasonically
generated. It is an inspection material. A laser light source 2 for generating a laser beam is
installed above the material to be inspected 1 at an appropriate distance from the material to be
inspected 1 and an area mask in which the laser light source 2 forms a slit in a concentric belt
shape. The concentric pattern of the area mask 13 is projected onto the surface of the inspection
material 1 by the lens 14. As a result, a local thermal stress is caused in the concentric belt-like
fresnel region I5 of the surface of the inspection object 1 irradiated with the laser light, and the
stress generates a mechanical stress in the material structure of the inspection object 1 As a
result, a sound source is generated and an elastic wave, ie, an ultrasonic wave 16 is generated.
The ultrasonic waves 16 generated from each of the Fresnel regions 15 are combined to form a
spherical wave front 17, and the synthesized spherical wave travels toward the center of
curvature 18 of the spherical wave front 17, and the generated ultrasonic wave 16 is generated.
Becomes focused on the center of curvature J8. [Problems to be Solved by the Invention]
According to the apparatus of Japanese Patent Application Laid-Open No. 53-134488 described
above, although it is possible to generate an ultrasonic wave focused in the inspection material 1
without contact, it is possible to produce a large output. There is a problem that energy beam
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generating means (laser light source) is required, and the entire apparatus is bulky. The present
invention has been made in view of the above circumstances, and the entire apparatus can be
made compact by using a plurality of small output energy beam generating means, and
ultrasonic waves can be focused, and a plurality of energy beams can be obtained. An object of
the present invention is to provide a noncontact ultrasonic wave generator capable of scanning
focused ultrasonic waves by controlling the irradiation timing of the generating means. [Means
for Solving the Problems] The noncontact ultrasonic wave generator according to the present
invention comprises a plurality of energy beam generating means arranged geometrically (lattice,
concentric, linear, etc.) In addition to this, a control circuit for controlling the irradiation timing of
these energy beam generating means is provided.
[Operation] In the non-contact type ultrasonic wave generator according to the present invention,
when the energy beam is simultaneously irradiated from the plurality of small output energy
beam generating means, the energy equivalent to the single large output energy beam generating
means is irradiated. An ultrasonic wave focused on the test material is generated. Further, when
the irradiation timing of the plurality of small output energy beam emitting means-is controlled,
the focusing position of the ultrasonic wave is moved. The present invention will be specifically
described below based on the drawings showing the embodiments. FIG. 1 is a schematic
perspective view showing the configuration of an embodiment of the non-contact type ultrasonic
wave generator according to the present invention, and in the figure, 1 is a material to be
inspected which is an ultrasonic wave generation target. A laser is provided with nine laser light
sources 2a, 2b, 2c, 2d, 2e, 2f, 2g, 2h, and 2i made of semiconductor laser at an appropriate
length N1 apart from the test material 1 on one side of the test material 1 A light source setting
unit 2 is provided. The nine laser light sources 2n, 2b, 2c, 2d, 2e, 2f, 2g, 2h, and 2+ are arranged
in a 3 × 3 grid and any laser light source emits light and the optical axis of the single light is It is
positioned so as to be perpendicular to the surface of the test material 1. Reference numeral 4
denotes a switching circuit, which emits a pulse signal for controlling the laser light sources 2a,
2b, 2c, 2d, 2e, 2f, 2g, 2h and 2i, and this pulse signal is inspected through the delay circuit 3R.
Three laser light sources 2a, 2b, 2c forming a line in the longitudinal direction of the material 1
through the delay circuit 3b and a laser light sources 2d, 2e, 2f forming a line in the longitudinal
direction through a delay circuit 3c It is also sent to the laser light source 2g + 2h + 2 + in a row
in the longitudinal direction. Next, the operation will be described. Three delay circuits 3a. The
pulse signal is sent from the switching circuit 4 to the delay circuits 3a, 3b and 3c with the same
delay time 3b and 3c or different delay times of the delay circuits 3a, 3b and 3c. Then, the output
from the delay circuit 3a is transmitted to the laser light sources 2a, 2b and 2c, and the laser
light sources 2a, 2b and 2c irradiate the laser light to the surface of the inspection material 1 in
synchronization with the output signals. Form 5a, 5b, 5c. Similarly, the laser light sources 2+], 2e,
and 2f are irradiation beam lines in synchronization with the output signal from the delay circuit
3b) 5d. The laser light sources 2g, 2h and 2i form irradiation beam spots 5g + 511 + 5i in
synchronization with the output signal from the delay circuit 3G.
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Then 9 (IM irradiation beam spots 5a, 5b, 5c, 5d. In 5e, 5r, 5g, 5b, 5i, thermal expansion occurs
instantaneously due to absorption of light. As a result, the irradiation beam spots 5a, 5b, 5c.
Ultrasonic waves are generated by local heat stress at 511 + 50 + 5 r + 5 g + 5 h + 51. Then, for
the same reason as described in the prior art, one of the ultrasonic waves in the inspection
material 1; 'i (if the laser light is emitted from nine laser light sources at the same time, the lower
part of the laser light source 5e Will be focused on the point I). Here, by adjusting the magnitude
of the delay time of the delay circuits 3a, 3b, 3c, it is possible to adjust the position at which the
ultrasonic waves converge on the test material 1. For example, when the delay times are
increased in the order of the delay circuits 3a, 3h, 3c, the focusing positions of the ultrasonic
waves can be shifted to the irradiation beam spots 5g, 5h, 5i. When the delay times of the delay
circuits 3a and 3c are set to 0 and the delay time set only for the delay circuit 3b is set, the
focusing position is a shallow portion at the center in the width direction of the test material I.
Therefore, since the focusing position of the ultrasonic waves can be changed as described above,
by making the change continuous, the focused ultrasonic waves can be scanned in any direction.
Then, for example, the ultrasonic waves focused along the newly detected internal defect of the
inspection material can be scanned. Although the arrangement of the laser light sources is in the
form of a lattice in the present embodiment, the arrangement is not limited to this and may be
linear or concentric. FIG. 2 is a schematic view showing the configuration of another embodiment
of the present invention. In this embodiment, eleven laser light sources 2a in the form of-straight
lines are provided in the laser light source installation portion 2 above the inspection material l.
2b, 2c, 2a, 2e, 2f + 2g, 2h, 2i, 2J, 2k are installed. Further, unlike the embodiment shown in FIG.
1, there is no delay circuit, and the pulse signals from the switching circuit 4 simultaneously
drive eleven laser light sources. Then, the ultrasonic waves are focused at one point in the
inspection material 1 below the central laser light source 2r. If there is no need to scan focused
ultrasound, but only 4J to obtain focused ultrasound, the apparatus shown in FIG. 2 may be used.
The arrangement of the L nose light sources is not limited to a straight line, and may be a lattice
or a concentric circle. Next, a low power laser light source is used as in the previous embodiment,
but unlike the above embodiments, the laser light from each laser light source is applied to one
point on the surface of the test material!
(((An embodiment which is configured to emit ( FIG. 3 is a schematic view showing the
installation state of the laser light source of such an embodiment, and in this embodiment, the
laser light source installation portion 2 has a dome shape, and the center position of the dome
shape is It is a surface site which should not generate ultrasonic waves of the material 1. Note
that, as shown in FIG. 4 showing a plan view of the laser light source installation unit 2, the laser
light sources 2a, 2h,... In this embodiment are arranged on the circumference of concentric
circles in plan view of the laser light source installation unit 2. When the laser light source is
installed in this way, the laser light from each lathe light source is condensed on one point on the
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surface of the inspection material 1, so even if the output of the laser light source is small It can
emit light. Further, by changing the curvature of the dome or the distance to the inspection
material 1, the degree of focusing of the laser light from each laser light source on the surface of
the inspection material 1 can be freely changed. The arrangement of the laser light sources is not
limited to being concentric, but may be lattice or straight. Further, the shape of the laser light
source installation portion is not limited to the dome shape, and may be semi-cylindrical in which
the opening portion is directed to the inspection object 1 side. In this case, the laser light does
not converge at one point but converges in a straight line. In addition, although the case where
the laser light source is installed in the laser light source installation portion where the
installation surface has a curved surface shape has been described, the present invention is not
limited thereto. The laser light source may be provided by adjusting its installation angle so as to
focus on one point on the surface. [Effects] As described in detail above, in the present invention,
instead of using a high-power laser light source, a plurality of low-power laser light sources are
geometrically arranged to generate ultrasonic waves in the test material. The whole is small scale
and inexpensive and can generate focused ultrasound. Further, by controlling the irradiation
pattern of the plurality of laser light sources, it is possible to scan focused ultrasonic waves, for
example, it is possible to scan focused ultrasonic waves along defects detected in internal defect
detection. In addition, since the laser light from each laser light source is condensed at one point,
even a low power laser light source can generate a predetermined ultrasonic wave.
[0002]
Brief description of the drawings
[0003]
FIG. 1 is a schematic view of a noncontact ultrasonic wave generator according to the present
invention, FIG. 2.3 is a schematic view showing another embodiment of the present invention,
and FIG. 4 is a schematic view showing an arrangement pattern of laser light sources. FIG. 5 is a
schematic view of a conventional noncontact ultrasonic wave generator.
1: Test material 2a, 2b, 2c,-Laser light source 3a, 3b. 3c ... at = circuit 4 ... switching circuit In the
figure, the same reference numerals indicate the same or corresponding parts. B. Ibaraki Oiwa
Masuo 4, Sui, Thirifth Round 1st 21st Il] Fig. 3 Fig. 4 Fig. 5 Figure Procedure Correction
(Spontaneous) Showa 6 ebg October 6
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