Sound velocity thickness measurement method and device therefor

Abstract

To provide a sound velocity thickness measurement method capable of measuring a sound velocity and a thickness by even a laser ultrasonic method, and a device therefor.SOLUTION: A sound velocity thickness measurement method according to the present invention includes: irradiating a first and a second point as measurement objects with pulsed laser light and generating a first and a second ultrasonic wave (S1); contactlessly detecting the vibration of ultrasonic wave at a third point of which the first and second distances from the first and the second points are different (S2); determining a first time from a first generation time of the first ultrasonic wave till the first detection time of a first echo in the first round of reflection that occurred first on the reverse side, and a second time from a second generation time of the second ultrasonic wave till the second detection time of a second echo in the first round of reflection that occurred first on the reverse side (S3); and determining the sound velocity and the thickness at the measurement objects on the basis of the first and second distances and the determined first and second times (S5).SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a sound velocity thickness measurement method and a sound velocity thickness measurement device for measuring the sound velocity and thickness of a flat portion of a measurement target. [Background technology]

[0002] There is a need for non-contact measurement of the sound velocity and thickness of a measurement target, particularly in the steel industry where measurements are performed in harsh environments such as at high temperatures. A technology for non-contact measurement of sound velocity and thickness is disclosed in, for example, Patent Document 1.

[0003] The material thickness measurement method disclosed in the above-mentioned Patent Document 1 involves propagating ultrasonic waves in the thickness direction of the material, detecting multiple bottom echoes of the ultrasonic waves from the bottom surface of the material, measuring the propagation times of at least three different bottom echoes from the detection signals, obtaining a quantity related to the ratio of the distance between the ultrasonic transmitting and receiving positions and the thickness of the material from the propagation times, and calculating the thickness of the material using the quantity related to this ratio and the value of the distance between the ultrasonic transmitting and receiving positions. More specifically, in the above-mentioned Patent Document 1, when the distance (offset amount) between the ultrasonic generating means and the ultrasonic detecting means is s, the material thickness is d, the propagation time of the bottom echo is t, the time difference between the trigger signal and the ultrasonic generation time in the propagation time measurement is δt, and the sound speed is V, V×(t-δt)=2×(d 2 +(s / 2) 2 ) 1 / 2 The material thickness d is calculated by simultaneously calculating the above relationships for the propagation times t2, t4, and t6 of the three bottom echoes. Therefore, although Patent Document 1 does not directly mention it, the sound velocity and thickness can be calculated based on the above relationships. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2003-279340 A Summary of the Invention [Problem to be solved by the invention]

[0005] By the way, as a method of transmitting and receiving ultrasonic waves in a non-contact manner, for example, an electromagnetic ultrasonic method and a laser ultrasonic method are known. In the electromagnetic ultrasonic method, since the propagation efficiency between the probe and the measurement object is small, it is necessary to bring the probe close to the measurement object and to enlarge the probe. When the probe is enlarged, in the above-mentioned Patent Document 1, the offset amount s becomes large, and in order to receive the bottom echo by the ultrasonic detection means without receiving it by the ultrasonic generation means in the juxtaposed ultrasonic generation means and ultrasonic detection means, the thickness of the measurement object needs to be a predetermined value or more. Therefore, it is not possible to measure a measurement object having a thickness less than the predetermined value. On the other hand, in the above-mentioned laser ultrasonic method, it is not necessary to bring the probe close to the measurement object, and the offset amount s can be made small, but in the above-mentioned Patent Document 1, it is necessary to receive three bottom echoes. The second and third back-wall echoes are harder to distinguish than the first back-wall echo because their intensity (amplitude) is lower due to attenuation, and it is necessary to distinguish the second and third back-wall echoes from noise caused by vibrations of the measurement target, etc. In particular, in a high-temperature environment, attenuation is large, and there may be cases where the third back-wall echo cannot be received.

[0006] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a sound velocity thickness measurement method and a sound velocity thickness measurement device that can measure sound velocity and thickness even by a laser ultrasonic method. [Means for solving the problem]

[0007] As a result of various studies, the inventors of the present invention have found that the above object can be achieved by the present invention described below. That is, a sound velocity thickness measurement method according to one aspect of the present invention includes an ultrasonic wave generation step of generating first and second ultrasonic waves at first and second points, respectively, different from each other, on a surface of a flat plate-like portion of a measurement target by irradiating the first and second points with a pulsed laser beam, an ultrasonic wave detection step of non-contact detecting vibrations of ultrasonic waves at a third point different from the first and second points and at a first and second distance different from the first and second points, and detecting the vibrations of the ultrasonic waves at the third point in a non-contact manner from a first generation point at which the first ultrasonic wave is generated at the first point by the ultrasonic wave generation step. the first time from a second generation time at which the second ultrasonic wave is generated at the second point by the ultrasonic generation process to a second detection time at which the first second echo, which is first reflected by the back surface of the plate-like portion of the plate, is detected by the ultrasonic detection process; and the second time from a second generation time at which the second ultrasonic wave is generated at the second point by the ultrasonic generation process to a second detection time at which the first second echo, which is first reflected by the back surface of the plate-like portion ...According to another aspect of the present invention, there is provided a sound velocity thickness measurement device, comprising: an ultrasonic wave generation unit that generates first and second ultrasonic waves at first and second points, respectively, different from each other on a surface of a flat portion of a measurement target by irradiating the first and second points with a pulsed laser beam; an ultrasonic detection unit that detects vibrations of ultrasonic waves at a third point different from the first and second points, the third point being at a first and second distance different from the first and second points, in a non-contact manner; and a detection unit that detects vibrations of ultrasonic waves at a third point different from the first and second points, the third point being at a first distance different from the first and second points, from a first generation point when the first ultrasonic wave is generated at the first point by the ultrasonic wave generation unit, the first ultrasonic wave generated at the first point facing the surface. a time processing unit that calculates a first time from a first detection time point when the ultrasonic detector detects a first first echo that is first reflected by a rear surface of the target object and a second time from a second generation time point when the ultrasonic generator generates the second ultrasonic wave at the second point to a second detection time point when the ultrasonic detector detects a first second echo that is first reflected by the rear surface of the target object, and a sound speed and thickness processing unit that calculates the sound speed and thickness of the target object based on the first and second distances and the first and second times calculated by the time processing unit. Preferably, in the above-mentioned sound speed thickness measuring method and device, the first generation time point and the second generation time point are coincident with each other by synchronously irradiating the first and second points with pulsed laser light, respectively.A method for measuring a thickness at a speed of sound according to another aspect of the present invention includes an ultrasonic wave generating step of generating an ultrasonic wave at a first point on a surface of a flat portion of a measurement target by irradiating the first point with a pulsed laser beam, an ultrasonic wave detecting step of non-contact detecting a first vibration of the ultrasonic wave at a second point on the surface different from the first point, and detecting a second vibration of the ultrasonic wave at a third point on the surface different from the first and second points, the third point having a second distance between the third point and the first point different from the first distance between the first point and the second point, and detecting a second vibration of the ultrasonic wave at the third point from a point in time when the ultrasonic wave is generated at the first point by the ultrasonic wave generating step. a time processing step of calculating a first time from a generation time point when a first first echo that is first reflected by the back surface facing the first point is detected at the second point by the ultrasonic detection step, and a second time from a generation time point when the ultrasonic wave is generated at the first point by the ultrasonic generation step to a second detection time point when a first second echo that is first reflected by the back surface of the ultrasonic wave generated at the first point is detected at the third point by the ultrasonic detection step; and a sound speed and thickness processing step of calculating a sound speed and a thickness in the flat portion of the object to be measured based on the first and second distances, and the first and second times calculated by the time processing step.A sound velocity thickness measurement device according to another aspect of the present invention includes an ultrasonic wave generation unit that generates ultrasonic waves at a first point on a surface of a flat plate-like portion of a measurement target by irradiating the first point with a pulsed laser beam, a first ultrasonic wave detection unit that detects in a non-contact manner a first vibration of the ultrasonic waves at a second point on the surface different from the first point, a second ultrasonic detection unit that detects in a non-contact manner a second vibration of the ultrasonic waves at a third point on the surface different from the first and second points, the third point being a second distance between the third point and the first point different from a first distance between the first point and the second point, and a time series measurement of the ultrasonic waves generated at the first point from a time point when the ultrasonic wave generation unit generates the ultrasonic waves at the first point. the first ultrasonic detection unit detects at the second point a first echo, which is the first reflection of the ultrasonic wave from the rear surface opposite the front surface, and the second time from the generation time at which the ultrasonic wave is generated at the first point by the ultrasonic generation unit to the second detection time at which the second ultrasonic detection unit detects at the third point a first second echo, which is the first reflection of the ultrasonic wave generated at the first point from the rear surface; and a sound speed and thickness processing unit that calculates the sound speed and thickness in the flat portion of the object to be measured based on the first and second distances, and the first and second times calculated by the time processing unit.

[0008] In such a sound velocity thickness measurement method and device, the simultaneous equations of Equation 1 and Equation 2 relating to sound velocity and thickness are established between the geometrical relationship of the first to third points and the first and second times, as described later, so that the sound velocity and thickness can be obtained by detecting the first echo of the ultrasonic wave generated by the pulsed laser light. Therefore, the sound velocity thickness measurement method and device can measure the sound velocity and thickness even by the laser ultrasonic method.

[0009] In another aspect, the above-mentioned sound speed thickness measurement method further includes a distance processing step of imaging the first, second, and third points from a fourth point spaced a third distance from the surface of the flat portion of the object in the thickness direction of the object, and determining each of the first and second distances based on the imaging results.In another aspect, the above-mentioned sound speed thickness measurement device further includes an imaging unit that images the first, second, and third points from a fourth point spaced a third distance from the surface of the flat portion of the object in the thickness direction of the object, and a distance processing unit that determines each of the first and second distances based on the imaging results captured by the imaging unit.

[0010] Such a sound speed thickness measurement method and device determines the first, second and third points to determine the first and second distances, so there is no need to determine the first and second distances in advance, and the sound speed and thickness can be measured with high accuracy.

[0011] In another aspect, the above-mentioned sound speed thickness measurement method further comprises a separation distance measuring step of measuring the third distance in a non-contact manner.In another aspect, the above-mentioned sound speed thickness measurement device further comprises a separation distance measuring unit that measures the third distance in a non-contact manner.

[0012] Such a sound speed thickness measurement method and device measure the third distance, so there is no need to determine it in advance, and the sound speed and thickness can be measured with high accuracy even if disturbances such as vibration of the object to be measured occur during measurement or the thickness of the object to be measured fluctuates.

[0013] In another aspect, in the above-mentioned sound speed thickness measurement methods, the ultrasonic wave generating step splits one pulsed laser beam into two and irradiates each of the two split pulsed laser beams onto the first and second points. In another aspect, in the above-mentioned sound speed thickness measurement devices, the ultrasonic wave generating unit includes a laser beam irradiator that irradiates the pulsed laser beam, and a light branching unit that splits the one pulsed laser beam irradiated by the laser beam irradiator into two and irradiates each of the two split pulsed laser beams onto the first and second points. In the above-mentioned sound speed thickness measurement devices, preferably, the light branching unit includes a beam splitter that transmits a portion of the one pulsed laser beam irradiated by the laser beam irradiator so as to irradiate the first point and reflects the remainder, and a mirror that reflects the remainder reflected by the beam splitter so as to irradiate the second point.

[0014] When laser light is irradiated to the first and second points by the first and second laser light irradiating units, respectively, and at least one of the sound speed and the thickness varies over time, it is necessary to irradiate the pulsed laser light by synchronizing the first and second laser light irradiating units with each other. However, in the above-mentioned sound speed thickness measuring method and device, one pulsed laser light is divided into two and irradiated to the first and second points, respectively, so that synchronization is not required. Effect of the Invention

[0015] The sound velocity thickness measuring method and sound velocity thickness measuring device according to the present invention can also measure sound velocity and thickness using a laser ultrasonic method. [Brief description of the drawings]

[0016] [Figure 1] 1 is a block diagram showing a configuration of a sound velocity thickness measurement device in an embodiment. FIG. [Diagram 2] 4 is a flowchart showing an operation of the sound velocity thickness measurement device. [Diagram 3] FIG. 13 is a diagram showing a simulation result of the first echo as an example. [Figure 4]FIG. 4 is an enlarged view of a portion of FIG. [Diagram 5] FIG. 11 is a diagram for explaining a first modified embodiment. [Figure 6] FIG. 11 is a diagram for explaining a second modified embodiment. [Figure 7] FIG. 13 is a diagram for explaining a third modified embodiment. [Figure 8] FIG. 13 is a diagram for explaining a fourth modified embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, one or more embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the disclosed embodiments. In addition, configurations with the same reference numerals in each drawing are the same configurations, and their description will be omitted as appropriate. In this specification, when referring to a general term, a reference numeral without a subscript is used, and when referring to an individual configuration, a reference numeral with a subscript is used.

[0018] The sound speed thickness measurement device in the embodiment is a device that uses a laser ultrasonic method to measure both the sound speed and thickness of a flat portion of a measurement object, and includes an ultrasonic generator, an ultrasonic detector, a time processor, and a sound speed thickness processor. The ultrasonic generator generates first and second ultrasonic waves at first and second points, respectively, that are different from each other on the surface of the flat portion of the measurement object by irradiating the first and second points with a pulsed laser beam. The ultrasonic detector detects vibration of ultrasonic waves at a third point that is different from the first and second points and has first and second distances different from the first and second points, respectively. The time processing unit obtains a first time from a first generation time when the ultrasonic generating unit generates the first ultrasonic wave at the first point to a first detection time when the ultrasonic detecting unit detects a first first echo of the first ultrasonic wave generated at the first point, which is reflected for the first time by the back surface opposite to the front surface, and a second time from a second generation time when the ultrasonic generating unit generates the second ultrasonic wave at the second point to a second detection time when the ultrasonic detecting unit detects a first second echo of the second ultrasonic wave generated at the second point, which is reflected for the first time by the back surface. The sound speed thickness processing unit obtains the sound speed and thickness of the flat part of the measurement object based on the first and second distances and the first and second times obtained by the time processing unit. Hereinafter, such a sound speed thickness measurement device and a sound speed thickness measurement method implemented therein will be described in more detail.

[0019] Fig. 1 is a block diagram showing the configuration of a sound velocity thickness measurement device in an embodiment. Fig. 1 also shows a front view of an image sensor of an imaging unit 3.

[0020] As shown in FIG. 1, the sound velocity thickness measurement device 1000 in the embodiment includes, for example, first and second laser light irradiation units 1-1, 1-2, an ultrasonic detection unit 2, an imaging unit 3, a separation distance measurement unit 4, a control processing unit 5, and a memory unit 9, and in the example shown in FIG. 1, further includes an input unit 6, an output unit 7, and an interface unit (IF unit) 8.

[0021] The first and second laser light irradiating units 1-1 and 1-2 are connected to the control processing unit 5 and are devices that irradiate pulsed laser light to first and second points PT1 and PT2, which are different from each other, on the surface of the flat plate-like portion of the measurement object Ob, respectively, according to the control of the control processing unit 5. For example, the first and second laser light irradiating units 1-1 and 1-2 are configured to include a laser light source that can irradiate laser light in a pulsed manner. The measurement object Ob may be any member as long as it can propagate ultrasonic waves from the surface to the back surface opposite the surface and propagate an echo (reflected wave) of the ultrasonic waves reflected by the back surface to the surface. Since the sound speed thickness measuring device 1000 in this embodiment can also perform measurements under severe environments such as high temperatures, for example, the measurement object Ob is a steel material under manufacture. When at least one of the sound speed and thickness of the measurement object Ob varies with time, the first and second laser light irradiating units 1-1 and 1-2 irradiate pulsed laser light in synchronization with each other according to the control of the control processing unit 5. For example, the control processing unit 5 simultaneously outputs a trigger signal instructing the irradiation of a pulsed laser beam to each of the first and second laser beam irradiators 1-1 and 1-2. As a result, the first and second laser beam irradiators 1-1 and 1-2 irradiate the pulsed laser beam in synchronization with the trigger signal. If neither the sound speed nor the thickness of the measurement object Ob varies with time, the first and second laser beam irradiators 1-1 and 1-2 do not need to irradiate the pulsed laser beam in synchronization (i.e., they may irradiate the pulsed laser beam asynchronously). By the irradiation of the pulsed laser beam, a first and second ultrasonic wave are generated at the first and second points PT1 and PT2, respectively, by ablation (ablation mode) or thermal expansion (thermal mode).

[0022] The first ultrasonic wave US1 generated at the first point PT1 propagates through the measurement object Ob and is reflected by the back surface of the measurement object Ob, and the first echo EC1 of the reflected ultrasonic wave propagates through the measurement object Ob and propagates to a third point PT3 on the surface of the measurement object Ob. Similarly, the ultrasonic wave US2 generated at the second point PT2 propagates through the measurement object Ob and is reflected by the back surface of the measurement object Ob, and the second echo EC2 of the reflected ultrasonic wave propagates through the measurement object Ob and propagates to a third point PT3 on the surface of the measurement object Ob. The third point PT3 is a point different from the first and second points PT1 and PT2, and is a point having different first and second distances l1 and l2 from the first and second points PT1 and PT2, respectively (l1 ≠ l2).

[0023] The ultrasonic detector 2 is connected to the control processor 5 and detects ultrasonic vibration at the third point PT3 in a non-contact manner on the surface of the object to be measured Ob under the control of the control processor 5. The ultrasonic detector 2 only needs to detect the presence or absence of ultrasonic waves at the third point PT3 in order to obtain the propagation time from each point PT1, PT2, and therefore detects ultrasonic vibration by, for example, any of the displacement, velocity, and acceleration caused by the ultrasonic vibration. The ultrasonic detector 2 is configured, for example, with a laser interferometer that detects the Doppler shift caused by the ultrasonic vibration. Alternatively, for example, the ultrasonic detector 2 is configured with a laser displacement meter using a confocal method or a triangulation method. The ultrasonic detector 2 outputs the detection result to the control processor 5.

[0024] The first and second laser light irradiation units 1-1, 1-2 are each arranged, for example, by a transmitting support member or manually, so as to irradiate pulsed laser light to the first and second points PT1, PT2, respectively, and the ultrasonic detection unit 2 is arranged, for example, by a receiving support member or manually, so as to detect ultrasonic waves (echoes of ultrasonic waves) at the third point PT3.

[0025] The imaging unit 3 is connected to the control processing unit 5, and is a device that images the first to third points PT1 to PT3 from a fourth point PT4 spaced a third distance l3 from the surface of the flat plate-like portion of the measurement object Ob in the thickness direction of the measurement object Ob under the control of the control processing unit 5. The imaging unit 3 is, for example, a digital camera 3 including an imaging optical system that forms an optical image of the object (here, the surface of the measurement object Ob including the first to third points PT1 to PT3) on a predetermined imaging plane, an image sensor that is arranged with its light-receiving surface aligned with the imaging plane and converts the optical image of the object into an electrical signal, and an image processing unit that processes the output of the image sensor to generate image data that is data representing an image of the object. A digital camera 3, which is an example of an imaging unit 3, is supported by, for example, a support member and disposed so that a principal point of the imaging optical system (including a pinhole) is located at a fourth point PT4 and a normal line to the surface (surface of the flat portion) of the measurement object Ob passing through the fourth point PT4 coincides with the optical axis of the imaging optical system. The imaging unit 3 outputs the imaging result (image) to the control processing unit 5.

[0026] The separation distance measuring unit 4 is connected to the control processing unit 5, and is a device that measures the third distance l3 in a non-contact manner on the surface of the measurement object Ob under the control of the control processing unit 5. The separation distance measuring unit 4 is disposed so as to be able to measure the third distance l3. For example, the separation distance measuring unit 4 is disposed, for example, supported by a support member, so that distance measurement can be started from a plane that includes the fourth point PT4 and is parallel to the surface of the measurement object Ob (the surface of the flat plate portion). The separation distance measuring unit 4 is configured, for example, with a laser distance measuring device. The separation distance measuring unit 4 outputs the measurement result (the third distance l3) to the control processing unit 5.

[0027] The input unit 6 is connected to the control processing unit 5 and is a device for inputting various commands such as a command to start measurement, and various data required for operating the sound velocity thickness measurement device 1000, such as the name of the measurement object Ob, the measurement date, camera parameters, and the like, to the sound velocity thickness measurement device 1000, and is, for example, a keyboard, a mouse, and a plurality of input switches to which predetermined functions are assigned. The output unit 7 is connected to the control processing unit 5 and is a device for outputting commands and data input from the input unit 6, and the sound velocity and thickness of the measurement results, under the control of the control processing unit 5, and is, for example, a display device such as a CRT display, an LCD (liquid crystal display device), an organic EL display, or a printing device such as a printer.

[0028] The input unit 6 and the output unit 7 may be configured as a touch panel. In the case of configuring this touch panel, the input unit 6 is a position input device that detects and inputs an operation position, for example, a resistive film type or a capacitive type, and the output unit 7 is a display device. In this touch panel, a position input device is provided on the display surface of the display device, and one or more input content candidates that can be input to the display device are displayed. When a user touches a display position that displays the input content that the user wants to input, the position is detected by the position input device, and the display content displayed at the detected position is input to the sound velocity thickness measurement device 1000 as the user's operation input content. In such a touch panel, the user can easily intuitively understand the input operation, so that a sound velocity thickness measurement device 1000 that is easy for the user to handle is provided.

[0029] The IF unit 8 is connected to the control processing unit 5 and is a circuit that inputs and outputs data to and from, for example, an external device under the control of the control processing unit 5, and is, for example, an interface circuit of RS-232C, which is a serial communication method, an interface circuit using the Bluetooth (registered trademark) standard, an interface circuit using the USB standard, etc. The IF unit 8 may also be, for example, a communication interface circuit that transmits and receives communication signals to and from an external device, such as a data communication card or a communication interface circuit conforming to the IEEE802.11 standard, etc.

[0030] The storage unit 9 is connected to the control processing unit 5 and is a circuit that stores various predetermined programs and various predetermined data under the control of the control processing unit 5. The various predetermined programs include, for example, a control processing program, and the control processing program includes, for example, a control program, a time processing program, a distance processing program, and a sound velocity thickness processing program. The control program is a program that controls each of the units 1 to 4 and 6 to 9 of the sound velocity thickness measurement device 1000 according to the function of each unit. The time processing program is a program for obtaining a first time t1 from a first generation time point when the first ultrasonic wave US1 is generated at the first point PT1 by the first laser light irradiating unit 1-1 to a first detection time point when the ultrasonic wave detection unit 2 detects a first first echo EC1, which is the first reflection of the first ultrasonic wave US1 generated at the first point PT1 on the back surface opposite to the front surface, and a second time t2 from a second generation time point when the second ultrasonic wave US2 is generated at the second point PT2 by the second laser light irradiating unit 1-2 to a second detection time point when the ultrasonic wave detection unit 2 detects a first second echo EC2, which is the first reflection of the second ultrasonic wave US2 generated at the second point PT2 on the back surface. The distance processing program is a program for obtaining the first and second distances l1 and l2, respectively, based on the imaging result obtained by the imaging unit 3. The sound speed thickness processing program is a program for calculating the sound speed v and thickness d in the flat portion of the measurement object Ob based on the first and second distances l1 and l2, and the first and second times t1 and t2 calculated by the time processing program. The various types of predetermined data include data required for executing each of these programs, such as the name of the measurement object Ob, the measurement date, camera parameters, and the processing results of each program.

[0031] Such a storage unit 9 includes, for example, a ROM (Read Only Memory) which is a nonvolatile storage element, an EEPROM (Electrically Erasable Programmable Read Only Memory) which is a rewritable nonvolatile storage element, etc. The storage unit 9 also includes a RAM (Random Access Memory) which serves as a so-called working memory of the control processing unit 5 for storing data generated during execution of the predetermined program, etc. The storage unit 9 may also be configured to include a hard disk device with a relatively large storage capacity.

[0032] The control processing unit 5 is a circuit for controlling each of the units 1-4, 6-9 of the sound speed thickness measurement device 1000 in accordance with the function of each unit, and for obtaining the sound speed v and thickness d of the measurement object Ob. The control processing unit 5 is configured, for example, with a CPU (Central Processing Unit) and its peripheral circuits. In the control processing unit 5, a control unit 51, a time processing unit 52, a distance processing unit 53, and a sound speed thickness processing unit 54 are functionally configured by executing the control processing program.

[0033] The control unit 51 controls each of the units 1 to 4 and 6 to 9 of the sound velocity thickness measurement device 1000 in accordance with the function of each unit, and is responsible for controlling the sound velocity thickness measurement device 1000 as a whole.

[0034] The time processing unit 52 obtains a first time t1 from a first generation time point when the first laser light irradiating unit 1-1 generates the first ultrasonic wave US1 at the first point PT1 to a first detection time point when the ultrasonic wave detecting unit 2 detects a first first echo EC1 at which the first ultrasonic wave US1 generated at the first point PT1 is first reflected by the back surface opposite to the front surface, and a second time t2 from a second generation time point when the second laser light irradiating unit 1-2 generates the second ultrasonic wave US2 at the second point PT2 to a second detection time point when the ultrasonic wave detecting unit 2 detects a first second echo EC2 at which the second ultrasonic wave US2 generated at the second point PT2 is first reflected by the back surface. More specifically, the time processing unit 52 outputs a first trigger signal instructing the first laser light irradiating unit 1-1 to irradiate the first point PT1 with the pulsed laser light. The output timing (output time point) of this first trigger signal is set to the first generation time point. The time processing unit 52 outputs a second trigger signal to the second laser light irradiating unit 1-2 to instruct the second laser light irradiating unit 1-2 to irradiate the second point PT2 with the pulsed laser light. The output timing (output time point) of this second trigger signal is set as the second generation time point. In the case of the synchronization, the first and second trigger signals are output simultaneously. Note that, if there is a time lag between the output time point of the trigger signal and the irradiation time point of the pulsed laser light, the time lag is measured in advance, and the first and second generation time points are corrected by the time lag. Next, the time processing unit 52 detects a first detection time point at which the first echo EC1 is detected from the detection result of the ultrasonic detection unit 2, and obtains a first time t1 by subtracting the first generation time point from the detected first detection time point ((first time point t1)=(first detection time point)-(first generation time point)). Similarly, the time processing unit 52 detects the second detection time when the first second echo EC2 is detected from the detection result of the ultrasound detection unit 2, and obtains the second time t2 by subtracting the second generation time from this detected second detection time ((second time t2) = (second detection time) - (second generation time)).In addition, when the irradiation of the pulsed laser light is synchronized, for example, the time processing unit 52 determines the magnitude relationship between the first distance 1 and the second distance l2 determined by the distance processing unit 53 as described below, and when the first distance l1 is smaller (shorter) than the second distance l2, it determines that the first detection timing (for example, the timing of the first peak) that appears in the detection result of the ultrasonic detection unit 2 after the first generation time point (=second generation time point) is the first detection time point, and determines that the next detection timing (the timing of the next peak) is the second detection time point. On the other hand, when the first distance l1 is larger (longer) than the second distance l2, the time processing unit 52 determines that the first detection timing that appears in the detection result of the ultrasonic detection unit 2 after the first generation time point (=second generation time point) is the second detection time point, and determines that the next detection timing is the first detection time point.

[0035] The distance processing unit 53 calculates the first and second distances l1, l2 based on the imaging result captured by the imaging unit 3. More specifically, the distance processing unit 53 calculates the first and second distances l1, l2 based on the imaging result captured by the imaging unit 3, the camera parameters of the imaging unit 3, and the measurement result of the separation distance measuring unit 4.

[0036] The sound speed thickness processing unit 54 obtains the sound speed v and thickness d in the flat portion of the measurement object Ob based on the first and second distances l1 and l2 and the first and second times t1 and t2 obtained by the time processing unit 52. More specifically, the following formulas 1 and 2 hold between them. Equation 1;2×((11 / 2) 2 +d 2 ) 1 / 2 = v × t1 Equation 2;2×((12 / 2) 2 +d 2 ) 1 / 2 = v × t2

[0037] From these, the sound speed v is given by the following equation 3, and the thickness d is given by the following equation 4. Equation 3;v=((12 2 -l1 2 ) / (t2 2 -t1 2)) 1 / 2 Equation 4;d=((((12 2 ×t1 2 )-(11 2 ×t2 2 )) / (t2 2 -t1 2 )) 1 / 2 ) / 2

[0038] Therefore, the sound speed / thickness processing unit 54 obtains the sound speed v from the above-mentioned formula 3, and obtains the thickness d from the above-mentioned formula 4.

[0039] The first and second laser light irradiating units 1-1, 1-2 correspond to an example of an ultrasonic generating unit that generates first and second ultrasonic waves at first and second points, respectively, different from each other on the surface of the flat portion of the measurement target by irradiating the first and second points with pulsed laser light.

[0040] The control processing unit 5, input unit 6, output unit 7, IF unit 8 and storage unit 9 in such a sound velocity thickness measurement device 1000 can be configured by, for example, a desktop or notebook computer.

[0041] Next, the operation of this embodiment will be described. Fig. 2 is a flow chart showing the operation of the sound velocity thickness measurement device. Fig. 3 is a diagram showing a simulation result of a first echo as an example. Fig. 4 is an enlarged view of a part of Fig. 3. In Figs. 3 and 4, the horizontal axis indicates time (elapsed time) [μs], and the vertical axis indicates amplitude.

[0042] When the sound velocity thickness measurement device 1000 having such a configuration is powered on, it initializes the necessary parts and starts its operation. In the control processing unit 5, a control unit 51, a time processing unit 52, a distance processing unit 53, and a sound velocity thickness processing unit 54 are functionally configured by executing a control processing program.

[0043] 2, when the manufacturing of the steel plate is started and, for example, an operator (user) instructs the start of measurement, first, in process S1, the sound velocity thickness measurement device 1000 simultaneously outputs control signals such as trigger signals to the first and second laser light irradiating units 1-1 and 1-2, the imaging unit 3, and the separation distance measuring unit 4 by the control processing unit 5, causes the first and second laser light irradiating units 1-1 and 1-2 to irradiate the first and second points PT1 and PT2 with pulsed laser light, generates first and second ultrasonic waves US1 and US2 at the first and second points PT1 and PT2, respectively, images the measurement object Ob by the imaging unit 3, and measures the third distance l3 by the separation distance measuring unit 4. As a result, the generation of the first and second ultrasonic waves US1 and US2, the generation of the image (measurement of the first and second distances l1 and l2), and the measurement of the third distance l3 are synchronized with each other. The sound velocity thickness measurement device 1000 stores the output timing of the control signal (trigger signal) as the first and second generation time points in the storage unit 9 by the control processing unit 5. When the imaging unit 3 generates an image (image data) of the measurement object Ob by imaging, it outputs the generated image (image data) to the control processing unit 5, and the sound velocity thickness measurement device 1000 stores the image (image data) in the storage unit 9 by the control processing unit 5. When the separation distance measurement unit 4 measures, it outputs the measured distance (third distance l3) to the control processing unit 5, and the sound velocity thickness measurement device 1000 stores the third distance l3 in the storage unit 9 by the control processing unit 5.

[0044] Next, the sound velocity thickness measurement device 1000 receives the detection results detected by the ultrasonic detection unit 2 through the control processing unit 5, detects the first and second echoes EC1 and EC2, stores the detection timing of the first echo EC1 in the memory unit 9 as the first detection time point, and stores the detection timing of the first echo EC2 in the memory unit 9 as the second detection time point (S2).

[0045] Next, the sound velocity thickness measurement device 1000, by the time processing unit 52 of the control processing unit 5, obtains a first time t1 by subtracting the first detection time from the first generation time, and obtains a second time t2 by subtracting the second detection time from the second generation time, and stores these first and second times t1, t2 in the memory unit 9 (S3).

[0046] Next, the sound velocity thickness measurement device 1000 determines the first and second distances l1, l2, respectively, by the distance processing unit 53 of the control processing unit 5 based on the imaging result (image) captured by the imaging unit 3 (S4).

[0047] Next, the sound velocity thickness measurement device 1000 uses the distance processing unit 53 of the control processing unit 5 to determine the sound velocity v and thickness d in the flat portion of the measurement object Ob using the equations 3 and 4 based on the first and second distances l1, l2 determined by the distance processing unit 53 and the first and second times t1, t2 determined by the time processing unit 52, and stores these determined sound velocity v and thickness d in the memory unit 9 (S5).

[0048] Then, the sound velocity thickness measurement device 1000 outputs the obtained sound velocity v and thickness d to the output unit 7 by the control processing unit 5 (S6), and ends this process. Note that the control processing unit 5 may output the sound velocity v and thickness d to an external device via the IF unit 8 as necessary.

[0049] In order to verify the measurement results of such a sound velocity thickness measurement device 1000, as an example, the simulation results of the first and second echoes are shown in Figures 3 and 4. In Figure 3, the part surrounded by the dashed oval β indicates the first first and second echoes, and in Figure 4, the part surrounded by the dashed oval α1 indicates the first first echo EC1, and the part surrounded by the dashed oval α2 indicates the first second echo EC2. In the simulation, in consideration of the actual measurement, the thickness of the material of the measurement object Ob was set to 10 [mm], the sound velocities of the longitudinal wave and the transverse wave were set to 5900 [m / s] and 3200 [m / s], respectively, and the first and second distances l1 and l2 were set to 3 [mm] and 6.5 [mm], respectively.

[0050] As shown in Fig. 4, the peak of the first first echo EC1 appears at 3.524 [μs], and the peak of the first second echo EC1 appears at 3.660 [μs]. Since the ultrasonic waves are generated by a pulsed laser beam, when calibrated (corrected) by the time difference between the start of ultrasonic generation and the peak of the ultrasonic waves (0.096 [μs] in this example), the first time t1 is 3.428 [μs], and the second time t2 is 3.564 [μs]. The sound speed v calculated from these is 5891 [m / s], which is almost the same as the set value (true value) of 5900 [m / s], and the thickness d measured is 10.02 [mm], which is almost the same as the set value (true value) of 10 [mm].

[0051] As described above, in the sound velocity thickness measurement device 1000 in the embodiment and the sound velocity thickness measurement method implemented therein, the simultaneous equations of the above-mentioned formulas 1 and 2 regarding the sound velocity v and thickness d are established between the geometrical relationship of the first, second and third points PT1 to PT3 and the first and second times t1 and t2, so that the sound velocity v and thickness d can be obtained by detecting the first first and second echoes EC1 and EC2 of the first and second ultrasonic waves US1 and US2 generated by the pulsed laser light. Therefore, the sound velocity thickness measurement device 1000 and the sound velocity thickness measurement method can measure the sound velocity v and thickness d even by the laser ultrasonic method.

[0052] The sound velocity thickness measurement device 1000 and the sound velocity thickness measurement method determine the first, second, and third points PT1-PT3 and then determine the first and second distances l1, l2. This eliminates the need to determine the first and second distances l1, l2 in advance, and allows the sound velocity v and thickness d to be measured with high accuracy.

[0053] The sound velocity thickness measurement device 1000 and the sound velocity thickness measurement method measure the third distance l3, so there is no need to determine it in advance. Even if disturbances such as vibrations of the measurement object Ob occur during measurement or the thickness of the measurement object Ob fluctuates, the sound velocity v and thickness d can be measured with high accuracy.

[0054] The sonic thickness measurement device 1000 and the sonic thickness measurement method measure the quantities l1, l2, l3, l1', and l2' other than the fourth distance l3' that can be given, so that the sonic speed v and the thickness d of the measurement object Ob, at least one of which varies with time, can be measured with high accuracy. Therefore, the sonic thickness measurement device 1000 and the sonic thickness measurement method are suitable for monitoring (monitoring) steel plates during production, for example.

[0055] In the above embodiment, the first and second distances l1, l2 are actually measured, but they may be measured in advance, input from the input unit 6, and stored in the storage unit 9. In this case, the imaging unit 3 is omitted, and the third distance l3 is not necessary, so the separation distance measuring unit 4 is also omitted.

[0056] In the above embodiment, the third distance l3 is also measured when the first and second distances l1 and l2 are measured, but the third distance l3 may be measured in advance, input from the input unit 6, and stored in the storage unit 9. In this case, the separation distance measurement unit 4 is omitted.

[0057] In addition, in the above-described embodiment, two first and second laser light irradiation units 1-1, 1-2 were used as an example of an ultrasound generating unit, but only one movable first laser light irradiation unit 1-1 may be used (first variant).

[0058] FIG. 5 is a diagram for explaining the first modified embodiment. For example, as shown in FIG. 5, a first ultrasonic wave is generated at a first point PT1 by irradiating a pulsed laser beam to the first point PT1 by the first laser beam irradiating unit 1-1, and then, for example, the first laser beam irradiating unit 1-1 is moved by a moving mechanism or manually, and a second ultrasonic wave is generated at the second point PT2 by irradiating a pulsed laser beam to the second point PT2 by the first laser beam irradiating unit 1-1. The moving mechanism is configured to include, for example, a rack and pinion and a motor for driving the pinion of the rack and pinion, and is disposed so that the rack of the rack and pinion is parallel to the surface of the measurement object Ob, and the pinion and the motor are attached to the first laser beam irradiating unit 1-1. In such a moving mechanism, the first laser beam irradiating unit 1-1 is guided by the rack by the pinion rotated and driven by the motor, and moves parallel to the surface of the measurement object Ob.

[0059] In addition, in the above-described embodiment, two first and second laser light irradiating units 1-1, 1-2 were used as an example of an ultrasound generating unit, but only one first laser light irradiating unit 1-1 may be used and further include a light branching unit that splits one pulsed laser light irradiated by the first laser light irradiating unit 1-1 into two and irradiates each of the two split pulsed laser lights to the first and second points PT1, PT2, respectively (second variant).

[0060] Fig. 6 is a diagram for explaining the second modified embodiment. For example, as shown in Fig. 6, the light branching unit includes a beam splitter 11 that transmits a part of one pulse laser beam irradiated by the first laser beam irradiating unit 1-1 so as to irradiate the first point PT1 and reflects the remaining part, and a mirror 12 that reflects the remaining part reflected by the beam splitter 11 so as to irradiate the second point PT2. In the example shown in Fig. 6, the laser beam irradiated by the first laser beam irradiating unit 1-1 and propagating along the vertical direction is incident on the beam splitter 11, the part of the laser beam transmitted through the beam splitter 11 propagates along the vertical direction and is irradiated to the first point PT1, and the remaining part of the laser beam reflected by the beam splitter 11 propagates along the horizontal direction and is incident on the mirror 12. The remaining laser light incident on mirror 12 is reflected by mirror 12 so that the propagation direction becomes the vertical direction, and this reflected remaining laser light propagates along the vertical direction and is irradiated to a second point PT2.

[0061] When laser light is irradiated onto the first and second points PT1, PT2 by the first and second laser light irradiating units 1-1, 1-2, respectively, and at least one of the sound speed and the thickness varies over time, it is necessary to irradiate the pulsed laser light from the first and second laser light irradiating units in synchronization with each other. However, in the sound speed thickness measurement device 1000 and the sound speed thickness measurement method in this second modified embodiment, one pulsed laser light is divided into two and irradiated onto the first and second points PT1, PT2, respectively, so that synchronization is not required.

[0062] In the above embodiment, the imaging unit 3 is disposed so that the normal line on the surface of the measurement object Ob passing through the fourth point PT4 coincides with the optical axis of the imaging optical system of the imaging unit 3, but this is not limited thereto, and the imaging unit 3 may be disposed so that the normal line intersects with the optical axis, for example, as shown in FIG. 7 (third modified form). FIG. 7 is a diagram for explaining the third modified form. In this case, the intersection angle θ between the normal line and the optical axis, in other words, the angle θ between the surface of the measurement object Ob (the surface of the flat plate-like portion) and the light receiving surface of the image sensor in the imaging unit 3, is input in advance to the sound velocity thickness measurement device 1000, and the distance processing unit 53 can obtain the first and second distances l1 and l2 based on the imaging result captured by the imaging unit 3, the camera parameters of the imaging unit 3, the measurement result of the separation distance measurement unit 4, and the intersection angle θ.

[0063] In the above-described embodiment, the sound velocity thickness measurement device 1000 is configured to generate first and second ultrasonic waves US1, US2 at the first and second points PT1, PT2, respectively, by irradiating each pulse laser beam by two first and second laser beam irradiators 1-1, 1-2, and to receive first and second echoes EC1, EC2 of the first and second ultrasonic waves US1, US2 by one ultrasonic detection unit 2. However, conversely, the sound velocity thickness measurement device 1000 may be configured to generate ultrasonic waves at a first point by irradiating a pulse laser beam by one laser beam irradiator, and to receive first and second echoes of the ultrasonic waves at two second and third points by two first and second ultrasonic detection units, respectively (fourth variant). In this case, the sound velocity thickness measurement device includes an ultrasonic wave generating unit that generates an ultrasonic wave at a first point on a surface of a flat plate-like portion of a measurement target by irradiating the first point with a pulsed laser beam, a first ultrasonic wave detecting unit that detects in a non-contact manner a first vibration of the ultrasonic wave at a second point on the surface different from the first point, a second ultrasonic wave detecting unit that detects in a non-contact manner a second vibration of the ultrasonic wave at a third point on the surface different from the first and second points, the third point being a second distance between the third point and the first point different from the first distance between the first point and the second point, and a second ultrasonic wave detecting unit that detects in a non-contact manner the second vibration of the ultrasonic wave at the third point from a point in time when the ultrasonic wave generating unit generates the ultrasonic wave at the first point. The measurement apparatus includes a time processing step for calculating a first time from a first detection time point when a first first echo that is first reflected by the back surface opposite the front surface is detected at the second point by the first ultrasonic detection unit, and a second time from a generation time point when the ultrasonic generation unit generates the ultrasonic wave at the first point to a second detection time point when the second ultrasonic detection unit detects a first second echo that is first reflected by the back surface of the ultrasonic wave generated at the first point at the third point; and a sound speed and thickness processing unit for calculating the sound speed and thickness in the flat portion of the object to be measured based on the first and second distances, and the first and second times calculated by the time processing unit.

[0064] 8 is a diagram for explaining the fourth modified embodiment. In comparison with the above-mentioned sound speed thickness measurement device 1000 shown in FIG. 1, the sound speed thickness measurement device 2000 in the fourth modified embodiment includes, for example, an ultrasonic wave generation unit 1 that generates ultrasonic waves US (US1, US2) at a third point PT3 on the surface of a flat plate-like portion of a measurement object Ob by irradiating the third point PT3 with a pulsed laser beam, a first ultrasonic wave detection unit 2-1 that detects a first vibration of ultrasonic waves at a first point PT1 on the surface different from the third point PT3 in a non-contact manner, a second ultrasonic wave detection unit 2-2 that detects a second vibration of ultrasonic waves at a second point PT2 on the surface different from the third and first points PT3 and PT1, the second distance l2 between the third point PT3 and the second point PT2 being different from the first distance l1 between the third point PT3 and the first point PT1 in a non-contact manner, and a detection unit 2-3 that detects a second vibration of ultrasonic waves at the second point PT2 in a non-contact manner when the ultrasonic waves US (US1, US2) are generated at the third point PT3 by the ultrasonic wave generation unit 1. a time processing unit 52 that calculates a first time t1 from the first point to a first detection time when the first ultrasonic detection unit 2-1 detects a first first echo EC1 at the first point PT1, the first echo EC1 being generated by the ultrasonic generating unit 1 at the third point PT3 and reflected for the first time by the rear surface opposite the front surface, and a second time t2 from the generation time when the ultrasonic generating unit 1 generates the ultrasonic US (US1, US2) at the third point to a second detection time when the second ultrasonic detection unit 2-2 detects a first second echo EC2 being generated by the ultrasonic US (second ultrasonic US2) at the third point PT3 and reflected for the first time by the rear surface, and a sound speed and thickness processing unit 54 that calculates a sound speed v and a thickness d in the flat portion of the measurement object Ob based on the first and second distances l1, l2 and the first and second times t1, t2 calculated by the time processing unit 52. The laser light irradiation unit 1 is configured to include, for example, a laser light source capable of irradiating pulsed laser light, similar to the above-mentioned first and second laser light irradiation units 1-1 and 1-2. The first and second ultrasonic detection units 2-1 and 2-2 are configured to include, for example, a laser interferometer that detects a Doppler shift caused by ultrasonic vibration, a confocal type or triangulation type laser displacement meter, etc., similar to the above-mentioned ultrasonic detection unit 2.Like the sound speed thickness measurement device 1000, the sound speed thickness measurement device 2000 in this fourth modified embodiment also includes a separation distance measurement unit 4 that measures the third distance l3 in a non-contact manner, and a distance processing unit 53 that determines the first and second distances l1, l2 based on the image pickup result captured by the image pickup unit 3, the camera parameters of the image pickup unit 3, and the measurement result of the separation distance measurement unit 4. The sound speed thickness measurement device 2000 in this fourth modified embodiment also exhibits the same effects as the sound speed thickness measurement device 1000 described above, and can measure the sound speed v and thickness d even by the laser ultrasonic method.

[0065] In order to express the present invention, the present invention has been described adequately and sufficiently through the embodiments with reference to the drawings in the above description, but it should be recognized that those skilled in the art can easily change and / or improve the above-mentioned embodiments. Therefore, unless the changes or improvements made by those skilled in the art are at a level that departs from the scope of the claims described in the claims, the changes or improvements are interpreted as being included in the scope of the claims. [Explanation of symbols]

[0066] 1000, 2000 Sound velocity thickness measuring device 1 Laser light irradiation unit 1-1 First laser light irradiation unit 1-2 Second laser light irradiation unit 2 Ultrasonic detection unit 2-1 First ultrasonic detector 2-2 Second ultrasonic detector 3. Imaging unit 4 Separation distance measuring section 5 Control processing section 9 Memory section 11 Beam splitter 12. Mirror 51 Control section 52 Time Processing Section 53 Distance Processing Unit 54 Sound speed thickness processing section

Claims

1. an ultrasonic wave generating step of irradiating a first and a second point different from each other on a surface of a flat portion of the measurement target with a pulsed laser beam to generate a first ultrasonic wave and a second ultrasonic wave at the first and the second point, respectively; an ultrasonic detection step of non-contactly detecting ultrasonic vibration at a third point different from the first and second points, the third point being at a first and second distance different from the first and second points, respectively; a time processing step of determining a first time from a first generation time point when the first ultrasonic wave is generated at the first point by the ultrasonic wave generation step to a first detection time point when the ultrasonic wave detection step detects a first first echo, which is the first reflection of the first ultrasonic wave generated at the first point on a back surface opposite to the front surface, and a second time from a second generation time point when the second ultrasonic wave is generated at the second point by the ultrasonic wave generation step to a second detection time point when the first second echo, which is the first reflection of the second ultrasonic wave generated at the second point on the back surface, is detected by the ultrasonic wave detection step; and a sound speed and thickness processing step of determining a sound speed and a thickness in the flat portion of the object to be measured based on the first and second distances and the first and second times determined by the time processing step. Sound velocity thickness measurement method.

2. an ultrasonic wave generating step of irradiating a first point on a surface of a flat portion of the measurement target with a pulsed laser beam to generate an ultrasonic wave at the first point; an ultrasonic detection step of non-contact detecting a first vibration of ultrasonic waves at a second point on the surface different from the first point, and non-contact detecting a second vibration of ultrasonic waves at a third point on the surface different from the first and second points, the third point having a second distance from the first point different from the first distance between the first point and the second point; a time processing step of determining a first time from a generation time point when the ultrasonic wave is generated at the first point by the ultrasonic wave generating step to a first detection time point when the ultrasonic wave generated at the first point is detected at the second point by the ultrasonic wave detecting step, the first first echo being the first reflection of the ultrasonic wave generated at the first point on a back surface opposite to the front surface, and a second time from a generation time point when the ultrasonic wave is generated at the first point by the ultrasonic wave generating step to a second detection time point when the ultrasonic wave detected at the third point is the first second echo being the first reflection of the ultrasonic wave generated at the first point on the back surface; and a sound speed and thickness processing step of determining a sound speed and a thickness in the flat portion of the object to be measured based on the first and second distances and the first and second times determined by the time processing step. Sound velocity thickness measurement method.

3. a distance processing step of imaging the first, second and third points from a fourth point spaced a third distance from a surface of the flat portion of the object in a thickness direction of the object, and determining the first and second distances based on the imaging results; The sound velocity thickness measuring method according to claim 1 or 2.

4. Further comprising a distance measuring step of measuring the third distance in a non-contact manner. The sound velocity thickness measurement method according to claim 3.

5. The ultrasonic wave generating step includes splitting one pulsed laser beam into two, and irradiating the first and second points with the two split pulsed laser beams, respectively. The sound velocity thickness measurement method according to claim 1.

6. an ultrasonic wave generating unit that generates first and second ultrasonic waves at first and second points, respectively, different from each other on a surface of a flat portion of the measurement target by irradiating the first and second points with a pulsed laser beam; an ultrasonic detection unit that detects ultrasonic vibration at a third point different from the first and second points, the third point being at a first and second distance different from the first and second points, in a non-contact manner; a time processing unit that calculates a first time from a first generation time point when the first ultrasonic wave is generated at the first point by the ultrasonic wave generating unit to a first detection time point when the ultrasonic wave detecting unit detects a first first echo caused by the first ultrasonic wave generated at the first point being first reflected by a back surface opposite to the front surface, and a second time from a second generation time point when the second ultrasonic wave is generated at the second point by the ultrasonic wave generating unit to a second detection time point when the ultrasonic wave detecting unit detects a first second echo caused by the second ultrasonic wave generated at the second point being first reflected by the back surface; a sound speed and thickness processing unit that calculates a sound speed and a thickness in the flat portion of the object to be measured based on the first and second distances and the first and second times calculated by the time processing unit; Sound velocity thickness measuring device.

7. an ultrasonic wave generating unit that generates ultrasonic waves at a first point on a surface of a flat portion of a measurement target by irradiating the first point with a pulsed laser beam; a first ultrasonic detection unit that detects a first vibration of an ultrasonic wave at a second point on the surface different from the first point in a non-contact manner; a second ultrasonic detection unit configured to non-contactly detect a second vibration of an ultrasonic wave at a third point on the surface different from the first and second points, the third point having a second distance from the first point different from the first distance between the first point and the second point; a time processing unit that calculates a first time from a generation time point when the ultrasonic wave is generated at the first point by the ultrasonic wave generating unit to a first detection time point when the first ultrasonic wave detecting unit detects at the second point a first echo, which is the first reflection of the ultrasonic wave generated at the first point on a back surface opposite to the front surface, and a second time from a generation time point when the ultrasonic wave is generated at the first point by the ultrasonic wave generating unit to a second detection time point when the second ultrasonic wave detecting unit detects at the third point a first second echo, which is the first reflection of the ultrasonic wave generated at the first point on the back surface; a sound speed and thickness processing unit that calculates a sound speed and a thickness in the flat portion of the object to be measured based on the first and second distances and the first and second times calculated by the time processing unit; Sound velocity thickness measuring device.

8. an imaging unit that images the first, second, and third points from a fourth point that is spaced a third distance from a surface of the flat portion of the measurement target in a thickness direction of the measurement target; a distance processing unit that calculates the first and second distances based on an image pickup result captured by the image pickup unit, 8. The sound velocity thickness measuring device according to claim 6 or 7.

9. Further comprising a separation distance measuring unit that measures the third distance in a non-contact manner.

9. The sound velocity thickness measurement device according to claim 8.

10. The ultrasonic wave generating unit includes a laser light irradiating unit that irradiates the pulsed laser light, and a light branching unit that divides one pulsed laser light irradiated by the laser light irradiating unit into two and irradiates each of the two divided pulsed laser lights to the first and second points, respectively.

7. The sound velocity thickness measurement device according to claim 6.

Images