KR101429348B1 - Nondestructive noncontact visual inspection apparatus and method for the internal crack detection of a specimen - Google Patents

Abstract

A non-contact type non-destructive image inspection apparatus for detecting defects in a specimen at high speed using a heater and a laser interferometer. The contactless image inspection apparatus includes a heating unit for irradiating thermal energy having a predetermined type of heat intensity periodically repeated on one surface of a specimen, a heating unit positioned on the upper and lower surfaces of the specimen in the lengthwise direction, A laser interferometer for generating a laser interference image on a surface different from the surface to which the thermal energy is applied in the specimen and a laser interferometer for generating a laser interferometer image from the laser interferometer, And a control and signal processing unit for controlling the heating unit.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a non-contact image inspection method and apparatus for detecting an internal defect in a specimen,

Embodiments of the present invention relate to a non-contact type non-destructive image inspection apparatus that detects defects in a specimen at high speed using a heater and a laser interferometer.

Defects inside the specimen can be detected by X-ray or ultrasound. In the case of X-ray inspection, large defects can be detected effectively, but detection is difficult in case of delamination or close defects. In the case of the defect detection method using the high-frequency ultrasonic waves, it is possible to effectively detect the detachment of the joint portion and the defect. However, in the case of ultrasonic inspection, it takes a lot of time to inspect all the areas of the specimen because the scanning inspection must be performed, and it is difficult for the non-expert to perform the inspection. In addition, since the specimen is very thin with a thickness of about several millimeters, high frequency ultrasonic waves of several tens of MHz or more must be used. Therefore, there is a drawback in that it is necessary to perform an inspection in water.

Embodiments of the present invention provide a non-contact type non-destructive image inspection apparatus for extracting defect information in a specimen. It is another object of the present invention to provide an inspection apparatus and method capable of precise defect detection, visually showing a defect image for the entire specimen at a time, and providing a defect image at high speed.

A non-contact type non-destructive defect image inspection apparatus according to embodiments of the present invention includes a heating unit for irradiating heat energy having a predetermined type of heat intensity periodically repeated on one surface of a specimen, A laser interferometer for generating a laser interference image on a surface different from the surface to which the thermal energy is applied in the specimen, and a laser interferometer for generating a laser interference image on the surface of the specimen, A signal processing function for extracting a defective image from the laser interference image generated by the laser interferometer, a screen display function, and a control and signal processing unit for controlling the heating unit.

According to one aspect, the heating section may include a contact heating device or a non-contact heating device.

According to one aspect, the spring support comprises a spring inwardly and is located at the top and bottom relative to the longitudinal direction of the specimen, and is fixed to prevent the specimen from stretching in the longitudinal direction when the specimen is stretched by thermal energy .

According to one aspect of the present invention, the laser interferometer includes a laser speckle interferometer capable of generating an in-deformation or out-of-variation interference image of the specimen, or a laser layer interferometer capable of obtaining a tilted deformed shape interference image of the specimen A laser interferometer.

According to one aspect, the control and signal processing section includes a computer, which obtains a phase-expanded phase image for the laser interference image, performs frequency conversion on the obtained phase image, And a signal processing function for performing an inverse frequency conversion. Alternatively, the control and signal processing unit may include a computer, wherein the computer monitors an input signal applied to the heating unit in real time, acquires a reference laser interference image at a specific input signal position selected by a user, A laser interference image is acquired and signal processing is performed in the input signal range to obtain a defective image, and then the defect image can be displayed on the screen. Alternatively, the control and signal processing unit may include a computer, and the computer may include a function of cumulatively averaging the defective images obtained in the input signal range set by the user in an input signal of the heating unit, which periodically repeats the same form, . ≪ / RTI >

Further, the control and signal processing section may include a computer, which obtains a phase-locked phase image with respect to the laser interference image, executes a low-pass filter on the obtained phase image to generate a low-frequency image, A difference image in which the defect information is emphasized by subtracting the obtained low-frequency image from the acquired phase image, and accumulating the obtained difference images in order to show the cumulative averaged image on the screen.

As described above, according to the embodiments of the present invention, since it is an image inspection method, it is possible to use a non-expert, and it is possible to perform high-speed inspection, and there is no risk of specimen damage because it is not an underwater inspection. Can be provided as an image.

1 is a view illustrating an internal configuration of a non-contact type image inspection apparatus for detecting an internal defect in a specimen using active thermal energy and a laser interferometer according to an embodiment of the present invention.
2 is a diagram illustrating an internal configuration of a non-contact type image inspection apparatus based on measurement of an out-of-deformed shape for detecting internal defects of a specimen using thermal energy and speckle laser interferometry using far-field illumination according to an embodiment of the present invention.
3 is a view illustrating an internal configuration of a non-contact type image inspection apparatus based on an in-deformation shape measurement for detecting internal defects of a specimen using thermal energy and speckle laser interferometer using far-field illumination according to an embodiment of the present invention.
FIG. 4 is a diagram illustrating an internal configuration of a non-contact type image inspection apparatus for detecting an internal defect in a specimen using a thermal energy and a layer milling laser interferometer using a contact type thermoelectric transducer (TE-Peltier) according to an embodiment of the present invention. Fig.
5 is a graph of a signal waveform of an input voltage applied to the thermal energy generating apparatus according to an embodiment of the present invention.
6 is a signal processing flowchart of a contactless image inspection apparatus for detecting an internal defect of a specimen using active thermal energy and a laser interferometer according to an embodiment of the present invention.
FIG. 7 is a flowchart of a cumulative averaging signal processing process for eliminating low-frequency components and emphasizing defect information in FIG. 6, and is a signal processing flowchart in which a1 portion of FIG. 6 is replaced.
8 is a view of a test specimen for a performance test of a non-contact type image inspection apparatus for detecting an internal defect of a specimen according to an embodiment of the present invention.
FIG. 9 is a view showing a phase unwrapping image for a fourth cycle of a specimen having an internal defect mounted on a fixing spring support according to an embodiment of the present invention. FIG.
FIG. 10 is a diagram after signal filtering of FIG. 6 for the phase spread image of FIG.
11 is a view normalizing a defect region in the filtered phase-spread image of FIG.
FIG. 12 is a view showing a phase-spread image for a fourth period of a voltage signal inputted after changing the lower part of the fixing spring supporting part supporting the specimen to the sponge supporting part.
FIG. 13 is a diagram after signal filtering for the phase-spread image of FIG. 12; FIG.
14 is a view normalizing a defect region in the filtered phase-spread image of FIG.
FIG. 15 is a graph showing the average image obtained by averaging the in-zone images set by the user among the images obtained by normalizing the defect region after signal processing in the phase image measured on the specimen mounted on the fixing spring support according to the embodiment of the present invention FIG.
FIG. 16 is a cumulative-averaged resultant image in which a defect is emphasized as a signal processing result of FIG. 7 according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited to or limited by the embodiments. In describing the present invention, a detailed description of well-known functions or constructions may be omitted for clarity of the present invention.

Hereinafter, a non-contact image inspection apparatus and method according to embodiments of the present invention will be described in detail with reference to FIGS. 1 to 16. FIG.

1 is a view illustrating an internal configuration of a non-contact type image inspection apparatus for detecting an internal defect in a specimen using active thermal energy and a laser interferometer according to an embodiment of the present invention. 1, a non-contact type image inspection apparatus using active thermal energy and a laser interferometer according to an embodiment of the present invention is a device for inspecting a noncontact image using a thermal interferometer such that the specimen 17 is periodically heated to a predetermined temperature, A fixing support 4 for preventing the specimen 17 from moving upward and downward by heat at the upper and lower sides of the specimen 17, And a control and signal processing unit 3 for performing signal processing on the laser interference video signal to obtain a defective image and controlling the peripheral device.

For reference, the 'front side' of the specimen 17 refers to the surface to be measured of the thermal deformation using the laser interference beam in the specimen 17, and the 'back side' refers to the opposite side of the front side.

The heating section 1 applies periodically repeated heat energy having a constant form tear strength, such as a sinusoidal shape, to the back surface of the specimen 17. Therefore, the specimen (17) repeats the cooling of the specimen (17) in proportion to the intensity of the applied thermal energy. At this time, the form and intensity of the thermal energy are controlled by the computer 11 in the control and signal processing unit 3. The computer 11 controls the signal generator 12 to determine a repetitive periodic signal in a predetermined form and also controls the voltage value of the signal. The output signal of the signal generator 12 is amplified by the control driver 13 to an intensity capable of controlling the heating unit 1 and controls the heating unit 1 device.

When the heat generated in the heating unit 1 heats the test piece 17 and the test piece 17 is repeatedly cooled, the test piece 17 is stretched in the longitudinal direction and the width direction of the test piece 17 and is repeatedly decreased. At this time, when thermal energy propagates inside the specimen 17, when the specimen 17 encounters the defect 18 inside the specimen 17, a part of the specimen 17 is reflected again. Therefore, the front surface of the defective specimen 17 has a degree of expansion and shrinkage of the specimen 17, It will have a different size from the defect location.

At this time, since the specimen 17 is fixed by the upper and lower fixed support portions 4, the specimen 17 is guided to the inside of the specimen 17 by the force which is stretched in the longitudinal direction by the thermal energy. Particularly, the lower spring support portion 15-1 and the upper spring support portion 16-1 inside the fixed support devices 15 and 16 located under and above the specimen 17 are supported by the lower fixed support 15-2 The upper and lower support devices 15 and 16 are fixed to the upper fixed support 16-2 and support the specimen 17 with a constant force in the upward and downward directions. 17 in the longitudinal direction and guiding the force toward the inside of the specimen 17. [ On the other hand, the upper and lower fixing support devices 15 and 16 of the upper and lower portions are fixed to the upper and lower portions of the specimen 17, respectively, but can freely move in the front and back directions of the specimen 17.

The laser interferometer 19 of the laser interferometer 2 obtains a deformed image on the front surface of the test piece 17 in the form of a laser interference image and the obtained image is processed by the computer 11 of the control and signal processing unit 3 And a defective image is obtained.

2 shows an internal configuration of a non-contact type image inspection apparatus based on measurement of an out-of-deformed shape for detecting an internal defect in the specimen 17 using thermal energy and a laser speckle interferometer using far-field illumination according to an embodiment of the present invention FIG.

The computer 11 in the control and signal processing unit 3 controls the signal generator 12 to generate a signal having a constant shape such as a sine wave and repeating periodically. The generated periodic signal is amplified to a signal capable of controlling the halogen lamp by the thermal lamp control driver 13-1. The amplified electric signal is applied to the upper halogen lamp 14-1 and the lower halogen lamp 14-2 in the heater 14 to generate thermal energy 20 having a periodically repeated intensity and the generated heat energy is Periodically heat and cool the sample (17) periodically.

When the heat generated in the heater 14 heats the test piece 17 and the test piece 17 is repeatedly cooled, the test piece 17 is stretched in the longitudinal direction and the width direction of the test piece 17 and is repeated. Since the specimen 17 is fixed by the upper and lower fixed supporting devices 15 and 16, the force of the specimen 17 is applied to the specimen 17 because the specimen 17 is stretched in the longitudinal direction due to thermal energy. Particularly, the lower spring support portion 15-1 and the upper spring support portion 16-1 inside the fixed support devices 15 and 16 located below and above the specimen 17 are fixed to the lower fixed support 15-2, And the upper and lower support devices 15 and 16 are fixed to the upper fixed support device 16-2 and the specimen 17 is supported by the constant force in the upward and downward directions. 17 in the longitudinal direction and guiding the constant force to the inside of the test piece 17. On the other hand, the upper and lower fixed support devices 15 and 16 can freely move in the front and back directions of the specimen 17.

The laser speckle interferometer 2-1, which is a component of the laser interferometer 2, obtains a deformed image in the vertical direction on the front surface of the test piece 17 in the form of a laser interference image, 3) and the defective image is obtained.

The laser speckle interferometer 2-1 converts a part of the beam of the measurement laser 21 reflected by the beam splitter 22 to a mirror 27, a beam diffusing optical system 28, a mirror 29 and a beam reduction optical system 30 Is reflected by the beam splitter 31, is incident on the camera 32, and is used as a reference beam. A part of the measuring laser 21 beam passed through the beam splitter 22 is reflected on the mirrors 23 and 25 and then irradiated on the front face of the specimen 17 after passing through the beam diffusing optical system 26. [ The irradiated laser beam image passes through the beam splitter 31 and is incident on the camera 32 as a measurement beam. The image formed on the camera 32 is picked up by an image in which the reference beam and the measurement beam are interfered with each other, and the picked-up image contains deformed shape information deformed vertically to the front surface of the specimen 17. The captured image is subjected to signal processing by the computer 11 and a defect image is extracted.

In order to obtain one laser interferometric phase image, the laser speckle interferometer (2-1) can obtain various phase shifted images. A plurality of phase shifted interference images can be obtained by using the phase shift of the laser beam by controlling the piezo sensor 33 attached to the piezo sensor driver 24 controlled by the computer 11 to move the mirror 25 . For example, if a laser interference image is obtained by a 4-bucket phase shift method, four phase shift (0 °, 90 °, 180 °, 270 °) interference images are obtained at high speed, (1) " (4) "

Here, in Equations (1) to (4), D is a direct current component of an image, Iac is a brightness intensity of each (x, y) position, and? Is a phase component to be measured.

A lapping phase map image obtained from these is obtained by the following equation (5).

The lapped phase map image Φ (x, y) is obtained by performing phase unwrapping ("2D phase unwrapping", DC Ghiglia and MD Pritt, A Willey-Interscience Publication, 1998) . The defect phase image is obtained by subtracting the current mutation phase map image from the reference mutation phase map image.

The laser speckle interferometer 2-1 shown in Fig. 2 is configured to measure the out-of-deformed shape by constructing a reference beam generated inside the interferometer and a measurement beam coming from the surface of the specimen 17 in parallel with each other, The invention is not limited to this, and may also include a laser speckle interferometer 2-1 for measuring an intra-parasitic deformed shape.

3 is a schematic diagram of a non-contact type image inspection apparatus based on an in-deformation shape measurement for detecting an internal defect in a specimen 17 using thermal energy and a laser speckle interferometer 2-1 using far-field illumination according to an embodiment of the present invention. Fig. The embodiment shown in FIG. 3 is identical to the embodiment shown in FIG. 2 except for the laser interferometer, and therefore the same reference numerals are used for the same constituent elements, and redundant explanations are omitted. The laser interferometer of Figure 3 removes the reference beam from the laser interferometer of Figure 2 and instead sends the signal reflected by the beam splitter 22 through the mirrors 27 and 29 to the existing top Plane deformed shape information of the measurement image by measuring the interference image of the two measurement beams by irradiating the new measurement beam onto the surface of the specimen 17 at a predetermined angle with respect to the measurement beam of the measurement beam.

FIG. 4 is a schematic diagram showing the internal structure of a non-contact type image inspection apparatus for detecting an internal defect of a test piece 17 using a thermal energy and a layer milling laser interferometer using a contact type thermoelectric element (TE-Peltier) according to an embodiment of the present invention. Fig.

Referring to FIG. 4, the computer 11 in the control and signal processing unit 3 controls the signal generator 12 to generate a signal having a constant shape such as a sine wave and repeating periodically. The generated periodic signal is amplified by the thermoelectric element control driver 13-2 into a signal capable of controlling the thermoelectric element 14-4 attached to the cooling plate 14-3. The amplified electric signal is applied to the thermoelectric element 14-4 attached to the cooling plate 14-3 of the heater 14 as the heating unit 1 so that heat energy having a periodic repetitive intensity is generated, Heat energy repeats the periodic heating and cooling of the specimen (17). At this time, the test piece 17 and the thermoelectric element may be attached in a contact manner, or may be in contact with each other through an intermediate medium such as a thermal grease to uniformize the heat transfer.

When the heat generated in the heater 14 heats the test piece 17 and the test piece 17 is repeatedly cooled, the test piece 17 is stretched in the longitudinal direction and the width direction of the test piece 17 and is repeated. Since the specimen 17 is fixed by the upper and lower fixed supporting devices 15 and 16, the specimen 17 is clogged in the longitudinal direction due to thermal energy, and the force is induced to be applied to the specimen 17 . Particularly, the lower spring support portion 15-1 and the upper spring support portion 16-1 in the fixed support portions 15 and 16 located at the lower portion and the upper portion of the specimen 17 are fixed to the lower fixed support portion 15-2, The upper and lower support devices 15 and 16 are fixed to the fixed support 16-2 of the test specimen 17 and support the specimen 17 with a constant force in the upward and downward directions. ) Of the specimen (17) and guiding the constant force to the inside of the specimen (17). On the other hand, the upper and lower fixed support devices 15 and 16 move freely in the front and back directions of the specimen 17.

The laser interferometer 2-2, which is a component of the laser interferometer 2, obtains a tilted image of the specimen 17 in the form of a laser interference image, And the defective image is obtained.

The laser layer milling interferometer 2-2 irradiates the laser beam of the measuring laser 21 onto the front face of the specimen 17 with the beam diffused through the beam intensity controller 41 and the beam diffusing optical system 26. [ The image on the front surface of the irradiated specimen 17 is divided into a beam transmitted through the beam splitter 42 and a reflected beam. The beam transmitted by the beam splitter 42 is reflected by a mirror 43 tilted at a certain angle? And is then reflected by the beam splitter 42 to become an incident beam 1 incident on the camera 32. The reflected beam is transmitted through a piezo Is reflected by a mirror 44 capable of being phase-shifted by a sensor 45 and then transmitted through a beam splitter 42 to be incident on a camera. The interference signal of the incident beam 1 and the incident beam 2 is imaged do. The interference image picked up by the camera contains the tilt-deformed image information on the front surface of the test piece 17. The interference image picked up by the camera is subjected to signal processing by the computer 11, and a defect image is extracted.

In order to obtain one laser interferometric phase image, the laser interferometer 2-2 can obtain various phase shifted images. A plurality of phase shifted interference images can be obtained by using the phase shift of the laser beam by controlling the piezo sensor 45 attached to the piezo sensor driver 24 controlled by the computer 11 to move the mirror 44 . The method of obtaining the phase image from the phase-shifted interference image is the same as the principle of the laser speckle interferometer 2-1 of Fig. However, since the obtained image is a slope image, only the integration process is added to the layer-milling interferometer.

Here, the heat lamp control driver 13-1 and the halogen lamps 14-1 and 14-2, which are the heating apparatuses of FIGS. 2 and 3, are connected to the thermoelectric-element control driver 13- 2, the cooling plate 14-3 and the thermoelectric element 14-4. Similarly, the thermoelectric element control driver 13-2, the cooling plate 14-3, and the thermoelectric element 14-4, which are the heating apparatus of FIG. 4, are the same as the heating lamp control driver 13-1 And the upper and lower halogen lamps 14-1 and 14-2.

FIG. 5 is a graph showing an example of a signal waveform of an input voltage applied to a thermal energy generating apparatus according to an embodiment of the present invention. Referring to FIG. As shown in Fig. 5, when the specimen 17 is heated with a sinusoidal heat intensity, defect information can be effectively detected at a specific position. Therefore, in the present invention, a user can observe a defect in real time by displaying an image of a specific section in which defect information is effectively detected on the screen. For example, as shown in FIG. 5, when a reference image is held at a position (0) in a sinusoidal toughness toughness signal repeated at a cycle of 10 seconds, a defect image is effectively observed at an input voltage between V1 and V2. Therefore, the user can visually check the defective image during the inspection process by displaying the image measured between V1 and V2 on the screen.

6 is a signal processing flowchart of a contactless image inspection apparatus for detecting an internal defect of a specimen using active thermal energy and a laser interferometer according to an embodiment of the present invention.

Referring to FIG. 6, the computer 11 can monitor the voltage input to the heater 14 in real time using an A / D converter (S1). When the input voltage reaches the set voltage value (S2), the user can obtain the reference fringe interference image at the specific setting position (S3). From the obtained reference fringe interference image, a reference phase map is obtained using Equation (5) (S4), and the expanded reference phase image can be obtained by spreading the phase map. In detail, when the reference phase map is obtained (S4), the computer 11 acquires the fringe image and acquires the input voltage (S5), obtains a new phase map continuously and repeatedly at high speed, And acquires a phase map (S6). The obtained differential phase map can be subjected to phase spreading to obtain an expanded phase map (S7). Next, the expanded phase map is subjected to signal filtering to obtain a defective image (S8). If the current defective image is within the defect display setting set by the user (if the voltage input for tangential control is within the display setting value) (S9), the screen is displayed (S10).

The computer 11 can effectively extract the defective image information by repeating such a signal processing process.

The signal filtering process S8 is performed by performing a frequency transformation (for example, a Fourier transform) on the phase-expanded phase image as shown in FIG. 6 (S81) (S82). The bandpass filter applied in the frequency domain is a filter for emphasizing and extracting a defect information part and passing only the frequency component between the lower end frequency f1 and the upper end frequency f2 set by the user. The band-pass filtered signal is subjected to inverse-Fourier transform (S83), and low-pass filtering is applied (S84). The low pass filter can be performed with a smoothing filter or a median filter. The bandpass filter used in the frequency domain has the effect of eliminating the entire deformation information of the test piece 17 while preserving the defect information. The low-pass filter used in the time domain performs a noise elimination function, which can often occur in speckle interference such as spike noise of an impulse pattern.

FIG. 7 is a signal processing flowchart for replacing the portion a1 in FIG. 6, in which a defective image is extracted by removing only low-frequency components from a phase-expanded phase image, Fig.

Specifically, the computer 11 copies the original image Oi to the phase-unfolding image S7 of Fig. 6 (S91). A low-pass filter such as a smoothing filter is applied to the phase-unfolded image S7 to generate a low-frequency image Li (S92). Then, the difference image Di (where Di = Oi-Li) is generated by subtracting the low-frequency image Li from the original image Oi (S93), and the accumulated difference image Di is accumulated in the accumulation buffer to generate a cumulatively averaged image (S94). At every measurement, the computer 11 generates a cumulative averaged image one by one, and displays the normalized cumulative image on the screen, thereby allowing the user to recognize the defective image with eyes (S95).

FIG. 8 is a view of a specimen 17 prepared for the performance test of a non-contact type image inspection apparatus for detecting an internal defect of a specimen according to an embodiment of the present invention. The test piece 17 is formed by attaching three metal plates using an epoxy metal adhesive. The rearmost plate on the drawing is an aluminum plate, and its size is 100 mm x 33 mm x 0.5 mm. The center plate is a tungsten plate and its size is 100 mm x 33 mm x 1.0 mm. The front plate is an aluminum plate and the size is 100 mm x 33 mm x 0.5 mm. In order to create a delamination defect between the center plate and the front plate, as shown by two dotted rectangles in the drawing, a square shape with rounded corners and having a size of 5 mm × 5 mm and a size of 3 mm × 3 mm I did not paint.

FIG. 9 is a view of a phase-spread image during a fourth cycle with respect to the internal defect sample 17 mounted on the fixing spring supporter 15-1, 16-1 according to an embodiment of the present invention, FIG. 11 is a view obtained by normalizing the defect region in the phase spread image of FIG. 10, and FIG. FIG. 12 is a view showing a state in which the lower portion of one of the fixing spring supporting portions 15-1 and 16-1 supporting the inner defect specimen 17 in FIG. 2 is changed to a soft sponge supporting portion, FIG. 13 is a view of the phase-unfolded image, FIG. 13 is a view after signal filtering for the phase-unfolded image of FIG. 12, and FIG. 14 is an image of a normalized defect region in the phase-unfolded image of FIG. At this time, the reference image was obtained in the (0) portion of FIG.

As shown in Figs. 9 to 14, the defective image is mainly observed at a specific portion of a certain period. For example, obtaining the reference value at the minimum value position of the input voltage provides excellent defect information at the minimum value position of the input voltage, and if the defect information is obtained at the maximum value position of the input voltage, . As shown in FIGS. 9 to 14, it can be seen that the support 4, which prevents deformation in the longitudinal direction with a constant force, effectively provides excellent defect information.

FIG. 15 is a graph illustrating a result obtained by normalizing the in-zone images set by the user among the images obtained by normalizing the defect region after signal processing in the phase image measured with respect to the specimen 17 mounted on the fixing spring support according to the embodiment of the present invention It is a drawing of the average image. FIG. 16 is a signal processing result of FIG. 7 according to an exemplary embodiment of the present invention. Referring to FIG. 7, phase images obtained during one cycle of the heater are cumulatively averaged It is a cumulative image drawing emphasizing the defect shown by normalization. Referring to FIGS. 15 and 16, it can be seen that defect information can be effectively displayed according to the non-contact type non-destructive image inspection method according to the present embodiment.

According to an embodiment of the present invention, the spring support portions 15-1 and 16-1 guide the deformation amount of the plate-like specimen 17 deformed by the thermal energy to the inside of the specimen 17, 18), it is possible to more clearly provide an internal defect image with improved detection resolution in the defect inspection process. Also, according to an embodiment of the present invention, defective images can be displayed in real time in the inspection process by using only data for a partial time period of a certain area in the heating cycle for applying heat as defect extraction information, You can check the image. According to an embodiment of the present invention, a bandpass filter operated in the frequency domain effectively extracts a defect information image included in the deformation information of the test piece 17, thereby improving the efficiency of detecting a defect. It is possible to display the defect image in real time.

Also, according to an embodiment of the present invention, an image obtained by removing only low-frequency components from a phase image and accumulating and cumulatively averaging the low-frequency components is effectively provided with defective image information.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The present invention is not limited to the above-described embodiments, and various modifications and changes may be made thereto by those skilled in the art to which the present invention belongs. Therefore, the spirit of the present invention should not be construed as being limited to the above-described embodiments, and all of the equivalents or equivalents of the claims, as well as the following claims, are included in the scope of the present invention.

1: heating section
2: Laser interferometer
2-1: Laser speckle interferometer
2-2: Laser layer milling interferometer
3: Control and signal processing section
4: Support
11: Computer
12: Signal generator
13: Control Driver
14: heater
13-1: Thermal lamp control driver
13-2: Thermoelectric device control driver
14-1: Top heat generating lamp
14-2: Lower heat generating lamp
14-3: Cooling plate
14-4: Thermoelectric element
15: Lower support device
15-1: Lower spring support
15-2: Lower fixed support
16: upper support device
16-1: Upper spring support
16-2: Upper Fixing Supporting Machine
17: The Psalms
18: Internal defect
19: Laser interferometer
20: Thermal energy
21: Measurement laser
22, 31: beam splitter
23, 25, 27, 29: mirror
24: Piezo sensor driver
26, 28: beam spreading optical system
30: Beam reduction optical system
26-1: beam diffusion optical system
32: Camera
33, 45: Piezo sensor
41: beam intensity controller
42: beam splitter
43, 44: mirror

Claims (8)

A heating unit for irradiating thermal energy on one surface of the specimen in the form of a sinusoidal wave periodically repeating the intensity of the thermal intensity in a predetermined form;
The test piece is held on the upper and lower surfaces in the longitudinal direction of the test piece to support the test piece with a predetermined force so as to be fixed with respect to the upward and downward directions of the test piece to prevent the test piece from being stretched in the longitudinal direction when the test piece is stretched by thermal energy. A spring support which is fixed to the base and includes a spring therein;
A laser interferometer for generating a laser interference image on a surface different from a surface to which the thermal energy is applied in the specimen; And
A signal processing function for extracting a phase image, which is a defect shape, from a laser interference image generated by the laser interfering unit, a screen displaying function, and a control and signal processing unit for controlling the heating unit;
For detecting an internal defect of a specimen.
The method according to claim 1,
Wherein the heating unit includes a contact type heating device or a non-contact type heating device.
delete The method according to claim 1,
Wherein the laser interferometer comprises:
A laser interferometer capable of generating an in-deformation or out-of-plane interference image of the specimen, or a laser interferometer capable of obtaining a tilted deformation interfering image of the specimen, A contactless image inspection device for detection.
The method according to claim 1,
Wherein the control and signal processing section comprises a computer,
Wherein the computer includes a signal processing function for obtaining a phase-expanded phase image with respect to the laser interference image, performing a frequency transformation on the obtained phase image, and performing band-pass filtering and inverse frequency transformation on the frequency domain, A contactless image inspection device for detection.
The method according to claim 1,
Wherein the control and signal processing section comprises a computer,
The computer monitors the input signal applied to the heating unit in real time, acquires a reference laser interference image at a specific input signal position selected by the user, acquires a laser interference image in an input signal range set by the user, And then displaying the defect image on the screen after the defect image is acquired.
The method according to claim 1,
Wherein the control and signal processing section comprises a computer,
The computer periodically cumulatively averages the defective phase images acquired in the input signal range set by the user in the input signal of the heating unit repeating the same form and displays the result on the screen, the non-contact type image Inspection device.
The method according to claim 1,
Wherein the control and signal processing section comprises a computer,
The computer obtains a deformed phase image of the specimen from the laser interference image, removes the low frequency component from the obtained deformed image, and accumulates the degenerated phase image sequentially after every measurement to generate a cumulative averaged image. Function
A contactless image inspection system for detecting internal defects of a specimen.

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