KR101057586B1 - Apparatus for imaging anomalous ultrasonic wave propagation - Google Patents

Abstract

PURPOSE: A deformed ultrasonic propagation imaging apparatus is provided to remotely collect ultrasonic wave generated from an object with high reproducibility at high speed using a pulse laser beam which is irradiated from a Q-switch CW laser. CONSTITUTION: A deformed ultrasonic propagation imaging apparatus(100) comprises a laser irradiating unit(120), a beam expander(160), a biaxial laser mirror scanner(130), a sensor(140), a first image processing controller(151), a second image processing controller(152), and an output unit(190). The laser irradiating unit irradiates a pulse laser beam. The beam expander controls the focus of the pulse laser beam. The biaxial laser mirror scanner controls the irradiation path of the pulse laser beam. The sensor senses the ultrasonic wave which is created by an object receiving the pulse laser beam. The first image processing controller comprises a bandpass filter letting only an ultrasonic signal of specific frequency band pass through. The second image processing controller eliminates the normal ultrasonic wave from the sensed ultrasonic wave and reconstructs a 3D ultrasonic wave structure using deformed ultrasonic wave. The output unit outputs the 3D ultrasonic wave structure created by the second image processing controller.

Description

Malformed ultrasonic wave imaging device {APPARATUS FOR IMAGING ANOMALOUS ULTRASONIC WAVE PROPAGATION}

The present invention relates to a malformed ultrasonic wave imaging apparatus, and more particularly, to a malformed ultrasonic wave imaging apparatus capable of quantifying damage size in a complex structure that is difficult to analyze in a simple ultrasonic wave imaging image.

3D ultrasound imaging is an ultrasound imaging technique that makes it possible to visualize changes over time, ie, propagation patterns, of acoustic ultrasonic waves in two-dimensional space by adding a time axis to two-dimensional spatial information.

Such researches on display methods have been followed by subsequent research and development since the first report in 2005.

1 is a scanning result of an ultrasound imaging apparatus developed by a research team at the Georgia Institute of Technology. Referring to FIG. 1, measurement is possible only on a flat plate structure according to an approach using an air-coupled transducer, and contactless measurement is not possible for remote measurement. In addition, scanning time is excessive because only scanning by planar motion is supported, and results are visible only in excessive damage such as 18.75mm open crack and 7.8mm open hole. low.

2 is an ultrasound imaging apparatus developed by a team of researchers at Sheffield University, UK. 3 is a scanning result of the ultrasound imaging apparatus of FIG. 2.

2 to 3, non-contact remote scanning is possible using a laser Doppler vibrometer (Polytech Co., Ltd. PSV-400), but it requires mounting of a focusing module for scanning the curvature and excessive inspection time for focusing. This takes In addition, it has low spatial resolution and sensitivity, a limit of the incident laser beam incident angle of ± 20 °, time for focusing, and excessive system price (200 million won per unit), which are visible only in excessive damage of 41.5mm open cracks. Ultrasonic wave images with remarkably low spatial resolution with scanning points of only 405 in the 110mm horizontal and 60mm vertical regions were output.

4 is a scanning result of the ultrasonic imaging apparatus developed by the research team of the Japan Institute of Industrial Technology.

Referring to FIG. 4, since the pulsed laser is used, rotational scanning of the curvature laser beam is possible, but the scanning speed is slow and the volume of the scanning system is unnecessarily large by applying the rotational scanning method of the heavy laser head. . In addition, due to the slow irradiation repetition rate of the pulsed laser, the inspection time is long and the signal reproducibility is insufficient due to the low stability. Therefore, the malformed ultrasonic wave propagation imaging technique described in the present invention cannot be applied. In addition, the results for the 16mm open cracks corresponding to the large damage were output only for the output.

5 to 6 are scanning results of a conventional ultrasound imaging apparatus.

5 to 6, since the Q-switch CW laser is used, a repetition rate of several kHz can be realized, and high-speed control scanning can be performed through a biaxial laser mirror scanner based on a galvano motor. The inspection time was at least 50 to 250 times faster than the pulsed laser and head scanning method of FIG. 4. However, in complex structures, the reflected waves, refraction waves, and scattered waves of ultrasonic waves at the boundary, adhesion, and fastening portions interfere with the normally progressing wave, and the wavelength is very complicated, so the wave induced by damage cannot be identified. There are many cases.

That is, the conventional ultrasound imaging apparatuses shown in FIGS. 1 to 6 cannot be remotely measured or curved structure scanning and require excessive inspection time or low spatial resolution due to a laser head scanning method and a slow irradiation repetition rate. .

In addition, due to the low signal reproducibility and slow irradiation repetition rate of pulsed lasers, it is limited to use only for excessive damage or interferes with the normal wave of reflected wave, refraction wave, dispersion wave, etc. There is a problem that cannot be solved.

An object of the present invention is to solve the problems of the prior art as described above, by removing the ultrasonic wave propagating normally and only three-dimensional imaging of the ultrasonic wave having a malformed propagation characteristics to determine the size of the damage in a complex structure difficult to analyze in a simple ultrasonic image It is to provide a malformed ultrasonic wave radiographic imaging apparatus to quantify.

The object of the present invention is not limited to the above-mentioned object, and other objects which are not mentioned will be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided a malformed ultrasonic wave imaging apparatus according to an aspect of the present invention, a laser irradiation unit for irradiating a pulsed laser beam, a beam expander for adjusting a focus for irradiating a pulsed laser beam to an object, and an inspection area within an object. A two-axis laser mirror scanner that allows the pulsed laser beam to be irradiated along the path of the laser beam irradiation point, a sensor for detecting ultrasonic waves generated by the object irradiated with the pulsed laser beam, an amplifier and an ultrasonic signal for amplifying the ultrasonic signal detected by the sensor Ultrasonic waves generated by the first image processing controller and the first image processing controller configured to remove only the noise present in the ultrasound signal and pass only a specific frequency band among the ultrasonic signals. Generated when there is a defect inside the object It may include a second image processing control unit for reconstructing the three-dimensional ultrasound structure using a malformed ultrasound and an output unit for outputting the three-dimensional ultrasound structure generated from the second image processing control.

The laser irradiation unit is characterized in that the Q-switch CW laser and the Q-switch CW laser is irradiated at a repetition speed of 10Hz to 10KHz and the irradiation output may be 0.1mJ to 99mJ.

The beam expander consists of a microscope lens and a focusing lens. The expansion ratio of the microscope lens can be determined by considering the beam diameter of the pulsed laser beam, the mirror size of the biaxial laser mirror scanner, and the expansion ratio of the microscope lens that can be refocused. The lens damage limit of the microscope lens and the focusing lens can be determined. It can be determined as the output per unit area of the beam.

The sensor may be used as two types of contact type attached to the object or non-contact type spaced apart from the object.

Non-contact sensors can use a laser beam or air as the medium.

Among the non-contact sensors, the laser ultrasonic receiver combines the pulsed laser beam and the receiving laser beam on the same laser beam path, and coincides the point where the laser beam irradiation point and the sensor detect the ultrasonic wave so that the ultrasonic wave is transmitted in the thickness direction of the object. can be used to detect out-of-plane propagation waveforms.

The second image processing controller may be configured to calculate a first ultrasonic wave detected at a first irradiation point among laser beam irradiation points and a second ultrasonic wave detected at a second adjacent irradiation point along a path of the first irradiation point and the laser beam irradiation point. An ultrasound recognizing unit to read out, a scaling unit moving the first ultrasound to the left or right direction by a multiple of the sampling interval on the time axis to generate the third ultrasound, and a difference in amplitude according to time of the third and second ultrasounds; A first calculator for generating a fourth ultrasound, a second calculator for calculating a root mean square (RMS) of the fourth ultrasound, a third calculator for selecting a fifth ultrasound that is the minimum among the calculated RMS values, and a fifth ultrasound It may include a component disposed on the beam irradiation point to generate a three-dimensional ultrasound structure.

The output unit may divide the 3D ultrasound structure generated from the second image processing controller according to time and continuously output the magnitude of the amplitude in the space on a color or gray scale.

In addition, this basic configuration is connected with a camera, a two-axis laser mirror scanner for remotely checking the object when performing a remote scanning test, and the two-axis laser mirror scanner is located beyond the limit of the angle to which the laser beam can be irradiated It can be configured by adding a hollow motor rotator to direct the located object to the exit of the two-axis laser mirror scanner.

The hollow motor rotator may include a hollow part through which the pulsed laser beam oscillated from the laser irradiation part may pass and a rotating part to rotate in a direction in which the pulsed laser beam is irradiated.

According to the present invention as described above, by using a pulsed laser beam irradiated by the high-definition Q-switch CW laser, ultrasonic waves generated in the object can be remotely collected at high speed with high reproducibility.

In addition, by using the feature that the ultrasonic waves in two adjacent scanning points are very similar to each other, the size of the damage in a complicated structure that is difficult to analyze through a simple ultrasonic wave image by removing the ultrasonic wave propagating normally and only three-dimensional imaging of the ultrasonic wave having a malformed propagation characteristic. It is effective to quantify.

1 is a scanning result of an ultrasonic wave imaging apparatus developed by a research team of the Georgia Institute of Technology.
2 is an ultrasonic wave imaging apparatus developed by a research team at the University of Sheffield, UK.
3 is a scanning result of the ultrasonic wave imaging apparatus illustrated in FIG. 2.
4 is a scanning result of an ultrasonic wave imaging apparatus developed by a research team of the Japan Institute of Industrial Technology.
FIG. 5 is a composite anterior specimen used for conventional ultrasonic wave imaging.
FIG. 6 is a simple ultrasonic wave imaging result of the specimen shown in FIG. 5.
7 is a schematic block diagram of a malformed ultrasonic wave imaging apparatus according to an embodiment of the present invention.
8 is a photograph of a composite wing specimen with impact damage to which the malformed ultrasonic wave imaging apparatus according to an embodiment of the present invention is applied.
FIG. 9 is a result of a simple ultrasonic wave imaging of the outer surface of the composite wing shown in FIG.
FIG. 10 is a malformed ultrasonic wave image obtained by imaging the outer surface of the composite wing shown in FIG. 8A using the malformed ultrasonic wave imaging apparatus of the present invention.
FIG. 11 is a path in which a pulsed laser beam is scanned and irradiated to an object by a laser mirror scanner according to an exemplary embodiment.
FIG. 12 is a diagram illustrating ultrasound waveforms y _i (t) and y _{i +1} (t) acquired at adjacent i-th and i + 1th irradiation points detected by a sensor according to an exemplary embodiment of the present invention. This is the result of adjusting the waveform to minimize the difference between the two waveforms and arranging the waveform representing the difference (y _{i +1} -y _i ) between the two waveforms so that the time axis becomes the depth direction at the i-th irradiation point.
13 is a flowchart of imaging a malformed ultrasonic wave propagation image.
FIG. 14 is a graph illustrating a result of obtaining a difference between two waveforms by moving one of ultrasonic waves y _i (t) and y _{i +1} (t) acquired at two adjacent irradiation points by a sampling interval.
FIG. 15 is a malformed ultrasound in which a three-dimensional ultrasound structure obtained by using a waveform representing the difference between two waveforms (y _{i +1} -y _i ) is divided at a specific time and the amplitude is output in a color scale in space. It is an image diagram.
FIG. 16 is an example of device configuration in a mobile format for performing malformed ultrasound propagation imaging in completely non-contact.
17 is an example of device configuration in a hangar stationary and mobile format that performs malformed ultrasonic propagation imaging in contact and non-contact.

Advantages and features of the present invention and methods for achieving them will become more apparent from the following detailed description, which will be described later in detail in conjunction with the accompanying drawings. Prior to this, terms and words used in the present specification and claims are to be interpreted in accordance with the technical idea of the present invention based on the principle that the inventor can properly define the concept of the term in order to explain his invention in the best way. It should be interpreted in terms of meaning and concept. In addition, if it is determined that the detailed description of the known functions and configurations related to the present invention may unnecessarily obscure the subject matter of the present invention, it should be noted that the detailed description thereof has been omitted.

7 is a schematic block diagram of a malformed ultrasonic wave imaging apparatus according to an embodiment of the present invention.

Referring to FIG. 7, the malformed ultrasonic wave imaging apparatus 100 according to an exemplary embodiment of the present invention may include a laser irradiator 120, a beam expander 160, a biaxial laser mirror scanner 130, a sensor 140, and an image. It includes a processing control unit 150.

Specifically, the Q-switch CW laser 120 irradiates the pulsed laser beam at a repetition rate of 10 Hz to 10 kHz. In this case, the pulsed laser beam irradiated may have a pulse-to-pulse instability (standard deviation / average) of 2% or less, and energy may range from 1 mJ (millijoule) to several tens of mJ, preferably 0.1, of ultrasonic waves to the object 110. It can be adjusted in the range of mJ to 99mJ, and the duration of the pulsed laser beam irradiation can be adjusted from several tens of picoseconds to several hundred nanoseconds.

Beam expander 160 is composed of a microscope lens and a coating to prevent damage to the lens in consideration of the irradiation power and wavelength of the focusing lens and the pulse laser beam that can be moved back and forth and focus. In this case, the expansion ratio of the microscope lens is adjusted from 10 times to 20 times, and the expansion ratio is determined in consideration of whether the beam diameter of the laser irradiation unit 120 and the mirror diameter and focus of the biaxial laser mirror scanner 130 can be readjusted.

The biaxial laser mirror scanner 130 includes a biaxial rotating part driven by a galvanomotor (galvano) to direct the pulsed laser beam irradiated from the laser irradiator 120 to the object 110. The pulsed laser beam is irradiated along the scanning pass, as shown in FIG. The ultrasonic signal irradiated along the scanning path is as shown in FIG. 12. The scanning path draws a specific pattern such as using an orthogonal coordinate system or an angular coordinate system according to the object 110, or adjusting a scan interval constantly or stepwise. When the signal-to-noise ratio of the sensor 140 is fundamentally low, the scanning pass may be repeatedly performed several times to average the signals obtained at the same irradiation point, thereby greatly improving the signal-to-noise ratio.

The sensor 140 is provided in the object 110 and includes a band pass filter and an amplifier, and ultrasonic waves generated by irradiating a pulsed laser beam to the object 110 are in-plane or out-of-object of the object 110. One-dimensional ultrasound is detected after propagating a certain distance in the plane. The one-dimensional ultrasound waves are signals formed by the amplitude of the time zone ultrasound wave as shown in FIG. 12.

 The one-dimensional ultrasonic signal sensed by the sensor 140 has a different amplitude and propagation time depending on the laser beam irradiation point. A band pass filter and an amplifier connected to the sensor 140 remove the signal amplification and noise, and pass through a specific frequency band to extract the corrected one-dimensional ultrasonic signal.

On the other hand, the sensor 140 according to the present invention is a piezoelectric material-based ultrasonic sensor (ceramic, single crystal, Air-coupled transducer, Macro fiber composite, Polyvinylidene fluoride), electromagnetic ultrasonic transducer (Electro-magnetic acoustic transducer), laser interferometer based ultrasonic It can be configured as either a sensor (Doppler vibrometer, laser ultrasonic multidetector receiver) or optical fiber ultrasonic sensor (FBG, Sagnac, EFPI). The sensor 140 may be provided in plurality in contact or non-contact.

FIG. 8 is a photograph of a composite wing specimen having impact damage to which a malformed ultrasonic wave imaging apparatus according to an embodiment of the present invention is applied, and FIG. 9 is a simple ultrasonic wave imaging of the outer surface of the composite wing illustrated in FIG. One result. FIG. 10 is a malformed ultrasonic wave image obtained by imaging the outer surface of the composite wing shown in FIG. 8 (a) using the malformed ultrasonic wave imaging apparatus of the present invention.

When the composite wing damage of FIG. 8 is imaged with a simple ultrasound propagation image (see FIG. 9), the ultrasound pattern is very complicated due to a complicated internal structure as shown in FIG. 8 (b) and cannot be analyzed. Therefore, as shown in (b) of FIG. 8, malformed ultrasound propagation imaging is performed to visualize damage of a complicated structure, and the malformed ultrasound propagation imaging process will be described in more detail with reference to FIGS. 13 and 14.

FIG. 13 is a flowchart of imaging a malformed ultrasound wave image, and FIG. 14 shows two waveforms while moving one of the ultrasonic waves y _i (t) and y _{i +1} (t) acquired at two adjacent irradiation points by a sampling interval. It is a graph of the result of obtaining the difference.

Since the ultrasonic waves measured at two adjacent irradiation points along the scanning path have almost no difference between the waveform and the arrival time, after moving one of the signals acquired at two adjacent irradiation points by a sampling interval as shown in FIG. As shown in 14d, the difference between the two signals is calculated for each sampling point. When outputting a waveform that shows the difference between two waveforms when the root mean square of the difference between two signals is minimized in a three-dimensional structure, a normally propagating waveform becomes very small and an abnormally propagating ultrasonic wave is measured with a relatively large amplitude. .

According to the algorithm for imaging the malformed ultrasonic wave of FIG. 13, the acquired ultrasounds, y _{i + 1} (t) and y _i (t), respectively, are read for two adjacent scanning points obtained in FIG. 12 (S111). The waveforms of y _{i + 1} (t) and y _i (t) which are read are as shown in Figs. 14A and 14C. y _{i + 1} (t) is shown in FIG. 14, for moving (S112) the waveform with the sampling interval (Δt) (b) is y _{i +} Move the y _{i + 1} (t) to the Δt time left as the sampling interval A waveform of ₁ (t + Δt) is shown. A waveform representing the difference of y _i (t) at y _{i +1} (t + Δt) is shown in FIG. 14 (d). In this way, the signals acquired at two adjacent irradiation points are shifted left and right by a multiple of the sampling interval and the difference between the two signals is obtained.

In order to minimize the difference between two signals, let y _{i +1} -y _{i be} the difference between y _i , Calculate the square root (RMS) of the square mean of each y _{i +1} -y _i obtained by moving left or right by a multiple of the sampling interval (S113) to select the signal representing the smallest RMS (S114). do. Y _i representing the difference between the selected signal, the waveform obtained at two adjacent survey points Alternatively, as shown in FIG. 12 at the irradiated position to obtain y _{i + 1} and generating a three-dimensional ultrasound structure using the waveforms obtained in the same manner with other irradiation points (S115) corresponding to the inspection area at a specific time. When the amplitude distribution is continuously output (S116) using a color or gray scale along the time axis, a malformed ultrasonic wave propagation image is obtained.

FIG. 15 is a process and result of imaging a spatially malformed ultrasonic wave at a specific time in a three-dimensional ultrasonic structure generated according to the algorithm for imaging the malformed ultrasonic wave of FIG. 13.

FIG. 16 is an example of a mobile configuration of a device in which a malformed ultrasonic wave imaging is performed completely non-contact, and FIG. 17 is an example of a hangar fixed and a mobile type in which a malformed ultrasound radiographic imaging is performed in contact and non-contact.

The malformed ultrasonic wave radiographic imaging apparatus may be configured as a mobile device as shown in FIG. 16. In addition, in terms of structural integrity management, it is possible to perform an automatic inspection as shown in FIG. 17 for a vehicle (eg, an aircraft, a train, etc.) or a fixed structure including an integrated sensor. FIG. 17 illustrates a hollow motorized rotator 170 through which a laser beam oscillated from a Q-switch CW laser can pass and a camera 180 capable of visualizing an inspection region in order to enlarge an irradiation region of a pulsed laser beam. It includes more. The inspection procedure and inspection result analysis may be performed in the central control room 200. The mobile and fixed malformed ultrasonic wave imaging apparatuses are utilized for power generation facilities, infrastructure, product quality evaluation of actual vehicle structures, and actual structural site health assessment.

Those skilled in the art will appreciate that the present invention can be embodied in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive. The scope of the present invention is indicated by the scope of the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and the equivalent concept are included in the scope of the present invention. Should be interpreted.

100: deformed ultrasonic wave imaging apparatus 110: the object
111: test area within the object 120: laser irradiation unit
130: 2-axis laser mirror scanner 140: sensor
150: image processing controller 151: first image processing controller
152: second image processing controller 153: third image processing controller
160: beam expander 161: microscope lens
162: focusing lens 170: hollow motor rotor
171: hollow portion 172: rotating portion
180: camera 190: output unit
200: central control room

Claims (13)

In the malformed ultrasonic wave imaging apparatus for inspecting whether there is a defect inside the object,
A laser irradiation unit for irradiating a pulsed laser beam;
A beam expander for adjusting a focus of the pulsed laser beam;
A two-axis laser mirror scanner that adjusts an irradiation path of the pulsed laser beam so that the pulsed laser beam is irradiated along a path of a laser beam irradiation point existing in the inspection area within the object;
A sensor for sensing ultrasonic waves generated by the object irradiated with the pulsed laser beam;
A first image processing controller including an amplifier for amplifying the ultrasonic signal sensed by the sensor and a band pass filter for removing noise present in the ultrasonic signal and passing only a specific frequency band among the ultrasonic signals;
The ultrasound generated by the first image processing controller removes the normal ultrasound generated when there is no defect inside the object, and reconstructs the 3D ultrasound structure by using malformed ultrasound generated when there is a defect inside the object. A second image processing controller; And
An output unit configured to output the 3D ultrasound structure generated by the second image processing controller; Malformed ultrasonic wave imaging device comprising a.
The method of claim 1,
The laser irradiation unit
A deformed ultrasonic wave imaging apparatus, characterized in that the Q-switch CW laser.
The method of claim 2,
The Q-switch CW laser
10. A malformed ultrasonic wave imaging apparatus according to claim 1, wherein the pulsed laser beam is irradiated at a repetition rate of 10 Hz to 10 kHz.
The method of claim 2
The Q-switch CW laser
And an irradiated output of the pulsed laser beam at 0.1 mJ to 99 mJ.
The method of claim 1,
The beam expander
Composed of microscope lens and focusing lens,
The expansion ratio of the microscope lens is determined in consideration of the beam diameter of the pulsed laser beam incident on the microscope lens, the expansion ratio of the microscope lens capable of refocusing, and the mirror size of the biaxial laser mirror scanner.
The lens damage limit of the microscope lens and the focusing lens is determined by the output per unit area of the pulsed laser beam.
The method of claim 1,
The sensor
An apparatus for malformed ultrasound propagation imaging, characterized in that the contact type attached to the object or the non-contact type spaced apart from the object.
The method of claim 6,
The non-contact sensor
And the pulsed laser beam or air is used as a medium.
The method of claim 6,
The non-contact sensor
Laser ultrasound receiver for detecting the out-of-plane propagation waveform transmitted in the thickness direction of the object by matching the laser beam irradiation point and the point where the sensor detects the ultrasonic wave
Malformed ultrasonic wave imaging device comprising a.
The method of claim 1,
The second image processing controller
Ultrasonic recognition unit for reading the first ultrasonic wave detected at the first irradiation point of the laser beam irradiation point and the second ultrasonic wave detected at the second irradiation point adjacent to the first irradiation point along the path of the laser beam irradiation point ;
A scaling unit configured to move the first ultrasound wave in a left direction or a right direction by a multiple of a sampling interval with respect to a time axis to generate a third ultrasound wave;
A first calculator configured to generate a fourth ultrasound that is a difference between amplitudes of the third ultrasound and the second ultrasound over time;
A second calculator configured to calculate a root mean square (RMS) of the fourth ultrasound;
A third calculating unit which selects a fifth ultrasonic wave which is the minimum among the calculated RMS values; and
And a structure unit for generating the three-dimensional ultrasonic structure by placing the fifth ultrasonic wave at the laser beam irradiation point.
The method of claim 1,
The output
The malformed ultrasound propagation imaging method comprises dividing the 3D ultrasound structure generated by the second image processing controller according to time and continuously outputting the magnitude of amplitude in a color or gray scale in space. Device.
The method of claim 1,
And a camera for remotely identifying the object when irradiating the pulsed laser beam.
The method according to claim 1 or 11, wherein
Connected to the biaxial laser mirror scanner,
Hollow motor rotator for directing an object located beyond the limit of the angle that the two-axis laser mirror scanner can irradiate the pulsed laser beam to the exit of the two-axis laser mirror scanner
Malformed ultrasonic wave imaging apparatus further comprising.
The method of claim 12,
The hollow motor rotor
A hollow part through which the pulsed laser beam irradiated from the laser irradiation part passes; And
Rotating part that rotates according to the direction in which the pulsed laser beam is irradiated
Malformed ultrasonic wave imaging apparatus comprising a.

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