KR102320174B1 - Surface Inspecting System Using Fringe Metric Method - Google Patents

Abstract

The present invention relates to a surface inspection system using a fringe metric method, which can extend the lifespan of lighting, comprising: a fringe lighting unit for irradiating light to an inspected object; a camera unit for acquiring a fringe image; and a control unit for generating a synthesized image.

Description

Surface Inspecting System Using Fringe Metric Method

The present invention belongs to a technique for analyzing the shape of the surface of a product using a fringe metric method.

As the types of smartphones increase and the usage cycle of the smartphone shortens, the industry for a system that quickly and accurately inspects various and many smartphones is growing. Accordingly, the market for the detection system for defects in the smartphone cover glass is also gradually increasing.

Currently, technologies for expressing the shape of the surface of an object include a film fringe method and a pattern projection method.

First, in the film fringe method, a fringe pattern is made by using a film with a stripe pattern in front of the lighting, and the film is moved to an appropriate position using a piezo to move the fringe to make a phase shift. have. This method greatly reduces the brightness of the light due to the film, and generally requires the use of a high-brightness light. And to change the fringe spacing in order to change the resolution of the measurement height, the film must be exchanged, and after the exchange, a complicated calibration process must be performed. In addition, this method has a problem in that the replacement cycle of the light is short because it uses a metal halide light with a shorter lifespan compared to other lights.

Next, the pattern projection method is a method of measuring the target object in three dimensions by projecting patterns at various intervals. However, in this method, the pattern must be moved mechanically, and there is a problem in that the mechanical vibration generated by the machine is affected by the precision. And since the scattered light of the pattern is used, there is a disadvantage in that it is difficult to measure a transparent object.

Republic of Korea Patent Registration No. 10-0824808 (Announcement date: 2008.04.24)

An object of the present invention is to solve a problem caused by using a fringe pattern to inspect the surface of a test object, a problem that requires high-brightness lighting, and a problem that occurs when the pattern is moved. In addition, in the existing technology, there is a difficulty in that the film needs to be exchanged in order to change the measurement height resolution.

In order to solve this problem, the present invention is configured so that the fringe pattern of various intervals can be converted simply by changing a parameter in a program such as an FPGA that controls lighting, so that the height resolution of the measurement object can be changed in real time. We want to solve the problem.

The technical problems of the present invention are not limited to the problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

The surface inspection system using the fringe metric method of the present invention for achieving the above technical problem includes a rotatable frame module, and a lighting module in which the first to eighth lights sequentially arranged on a straight line inside the frame module are installed. The fringe lighting unit that irradiates light to the test object, the camera unit that acquires a fringe image by photographing the object, and controls a plurality of lights at the set phase difference interval at a set period in nanosecond units, and one side of the plurality of lights After turning on the positioned lighting for a set time, it is located on the other side of the first phase signal, which turns off the first phase signal, and is turned on by the first phase signal, and is turned on by the first phase signal. and a controller for outputting a second phase signal for turning on the turned-off lights by the same number as the number of turned-on lights and applying the second phase signal to the lighting module. Here, after simultaneously turning on and off at least two lights, the controller turns on at least two lights that are turned off at the other side of the turned off lights at the same time, and outputs a first phase signal. Each time, the plurality of first fringe images acquired by the camera unit are arranged in a row according to the time sequence, and the plurality of second fringe images acquired by the camera unit are arranged in chronological order whenever the second phase signal is output. A fringe image receiving module arranged in a column, and a plurality of sequentially received first fringe images are arranged in a row to generate one first aligned image, and a plurality of second fringe images are arranged in a row to form one It includes an alignment module for generating a second aligned image, and a composite image generating module for generating a composite image by synthesizing the first aligned image to the second aligned image by calculating a preset equation.

The controller unit is located on the other side of the turned-on light during the second phase operation and turns on the off light and turns on the third phase signal, which operates the third phase, and is located on the other side of the turned-on light during the third phase operation It is possible to sequentially and repeatedly output the fourth phase signal that turns on the light and operates the fourth phase.

The controller unit acquires a third fringe image every time the third phase is activated, obtains a fourth fringe image every time the fourth phase is activated, obtains a plurality of first fringe images to a plurality of fourth fringe images, One fringe image is arranged in a row to generate one first aligned image, a plurality of second fringe images are arranged in a row to create one second aligned image, and a plurality of third fringe images are arranged in a row to create one third aligned image, and arranging a plurality of fourth fringe images in a row to create a fourth aligned image, synthesizing the first to fourth fringe images to create a surface height A composite image representing a car can be created.

The fringe image receiving module sequentially receives a plurality of first fringe images to a plurality of fourth fringe images photographed by the camera unit, and the alignment module arranges a plurality of sequentially received third fringe images in a row to form one Create a third aligned image of , arrange a plurality of fourth fringe images in a row to create a fourth aligned image, and arrange a plurality of fourth fringe images in a row to form a single fourth aligned image generated, and the composite image generating module may generate a composite image by synthesizing the third aligned image to the fourth aligned image using a preset formula.

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In the present invention, after aligning fringe images taken for a predetermined time into fringe images of the same phase, the aligned images are synthesized to generate a composite image having a height difference of a test object. Through these composite images, high detection power can be exhibited for dimples, scratches, and cracks in the edge part, which were difficult to detect in the production process.

In addition, the present invention has the advantage of extending the life of the lighting by using the LED lighting instead of the high-brightness lighting. In addition, the position of the lighting and the camera is free, and the high-speed measurement is possible through the system configuration of the line scan, and a fringe image is generated.

1 is a state diagram of a surface inspection system using a fringe metric method according to an embodiment of the present invention.
2 is a view showing a fringe lighting unit according to a first embodiment of the present invention.
3 is a view showing a fringe lighting unit according to a second embodiment of the present invention.
4 is a view showing a fringe lighting unit according to a third embodiment of the present invention.
5 is a block diagram showing the components of the controller of the present invention.
6 is a view showing an operating state of the fringe lighting unit according to the second embodiment of FIG.
7 to 9 are images obtained by obtaining a fringe image through a surface inspection system using a fringe metric method according to an embodiment of the present invention, converting and synthesizing the obtained fringe image.
10 to 12 are views showing the operating state of the lighting module included in the fringe lighting unit of the third embodiment that operates according to different cycles.
13 is a view showing a state in which a plurality of lighting modules are formed and operated as one lighting module group.

The drawings shown in the present specification and the description based on the drawings are one example that allows those of ordinary skill in the art to easily understand the present invention.

Accordingly, the drawings of the present invention and the detailed description for carrying out the invention do not limit the scope of the claims of the present invention. The claims of the present invention may be defined solely by the claims.

Hereinafter, a surface inspection system using the fringe metric method of the present invention will be described with reference to the drawings of the following examples of the present invention. However, in order to make the description of the present invention clear and concise, first, a surface inspection system using the fringe metric method will be generally described with reference to FIGS. 1 to 5 . Hereinafter, components constituting the surface inspection system using the fringe metric method will be described with reference to FIGS. 6 to 13 .

1 is a state diagram of a surface inspection system using a fringe metric method according to an embodiment of the present invention, FIG. 2 is a view showing a fringe lighting unit according to a first embodiment of the present invention, and FIG. 3 is a first embodiment of the present invention. It is a view showing a fringe lighting unit according to a second embodiment, and FIG. 4 is a view showing a fringe lighting unit according to a third embodiment of the present invention. And Figure 5 is a block diagram showing the components of the controller unit of the present invention.

The surface inspection system 1 using the fringe metric method of the present invention obtains an image line by line so as to be able to inspect the moving object B, and controls the brightness, phase and period of illumination for each individual line to scan once. It is possible to simultaneously acquire images with a phase difference in . As described above, the surface inspection system 1 using the fringe metric method of the present invention aligns the fringe images taken for a certain time with the fringe images of the same phase, and then synthesizes the aligned images to obtain a composite image with a difference in height of the inspected object. create Through this, the present invention can exhibit high detection power for dimples, scratches, edge cracks, etc., which were difficult to detect in the production process.

In addition, the present invention has the advantage of extending the life of the lighting by using the LED lighting instead of the high-brightness lighting. The surface inspection system 1 using the fringe metric method of the present invention is a first step of acquiring multiple phase fringe images with one scan of illumination cross control applied with TDM (Time Division Multiplexing), and synthesizing a plurality of phase difference images using FPGA or GPU Image conversion, synthesis, and pre-processing with Differential Fringe are performed in two stages, and FFT and AI applied image training defect detection and unchecked and over-tested are performed in three stages, which are dramatically improved.

The present invention includes the fringe lighting unit 10, the camera unit 20 and the controller unit 30 as components so as to exhibit the above-described characteristics.

Hereinafter, components included in the present invention will be described in detail. The fringe lighting unit 10 becomes a device capable of irradiating light at various angles to the inspection object B so that the camera unit 20 can photograph the inspection object B. The fringe lighting unit 10 includes a frame module 11 and a lighting module 12 . Here, the frame module 11 is a frame formed in the shape of a rectangular parallelepiped with an open bottom surface. And the lighting module 12 is a device for irradiating light to the test object (B) including a plurality of lights each controlled along the longitudinal direction inside the frame module (11). In the fringe lighting unit 10 , the frame module 11 is installed in an external fixed module (not shown), rotates on the floor A in a linear or oblique direction, and irradiates light to the test object B.

As shown in FIG. 2, the lighting module 12-1 of the fringe lighting unit 10 may be formed of a fringe lighting unit 10-1 including the first lighting units 01 to the eighth lighting units 08. have. Alternatively, the fringe lighting unit 10-1 is not limited to the formation as shown in FIG. 2, and if necessary, lighting including the first illumination 01 to the 16th illumination 16 as shown in FIG. It may be formed by being transformed into the fringe lighting unit 10-2 including the module 12-2. Alternatively, as shown in FIG. 4 , the lighting module 12-2 shown in FIG. 3 may be formed of three lighting modules 12-3 arranged in a straight line.

In this way, the fringe lighting unit may be formed by being variously deformed including a plurality of lights. Here, the lighting modules 12-1 to 12-3 are formed of LEDs to output constant light for a longer period of time than high-brightness halogen lighting.

The fringe lighting unit 10 turns on and off while moving a plurality of lights in order so that light can be output from a specific light. When the fringe lighting unit 10 outputs light, the camera unit 20 acquires a fringe image having a fringe according to the operation of the fringe lighting unit 10 by photographing the test object (B). The operating camera unit 20 may be operated by a control signal output from the controller unit 30 . More specifically, the camera unit 20 operates in synchronization with the operation in which a plurality of lights of the lighting modules 12-1 to 12-3 move and turn on and off, and the lighting modules 12-1 to 12-3 It works only when it is turned on and can take a test object (B).

The controller 30 generates a control signal and receives and processes data. The controller unit 30 becomes a computer that receives and processes data. The controller 30 is configured to control the illumination time and the delay time in nanosecond units when controlling the cross illumination using the line scan. Through this, the controller 30 allows the height resolution of the measurement object to be changed in real time.

Such a controller 30 includes a separate control board on which the FPGA chip is mounted as a limitation of the control board using the existing microcontroller CPU. In addition, the controller 30 may include a fringe image receiving module 310 , an alignment module 320 , and a composite image generating module 330 . Here, the fringe image receiving module 310 may sequentially receive a plurality of first fringe images C1 to a plurality of fourth fringe images C4 photographed by the camera unit 20 . And the alignment module 320 arranges a plurality of second fringe images C2 among a plurality of sequentially received first fringe images C1 to a plurality of fourth fringe images C4 in a row to form one second image. A second aligned image D2 may be generated, and one first aligned image D1 may be generated by arranging a plurality of first fringe images C1 in a row. In addition, one fourth aligned image D4 may be generated by arranging the plurality of fourth fringe images C4 in a row.

In addition, the composite image generation module 330 calculates the first aligned image D1 to the fourth aligned image D4 using a preset process and a preset formula, and then synthesizes the composite image E into a 2.5D or 3D stereoscopic image. ) can be created. Here, when the composite image E is generated in 2.5D, it may proceed based on the following equation.

보다 작으면 차가

보다 클 때까지

를 더 하는 (C)단계, Phase의 차가

보다 크면

보다 작을 때까지

를 빼는 (D)단계, 관심영역에 대해서 Y 방향으로 주위 픽셀과의 Phase의 차를 계산하는 (E)단계, Phase의 차가

보다 작으면 차가

보다 클 때까지

를 더 하는 (F)단계 및 Phase의 차가

보다 크면

보다 작을 때까지

를 빼는 (G)단계로 진행될 수 있다. And when a composite image (E) is created in 2.5D, the image is segmented to remove unnecessary regions and extract the region of interest (A), and the phase difference with the surrounding pixels in the X direction is calculated for the region of interest (B) , the difference of the phase

If less than the car

until bigger

(C) step of adding , the difference of the phase

greater than

until less than

(D) step of subtracting , (E) step of calculating the difference of the phase with the surrounding pixels in the Y direction for the region of interest, the phase difference

If less than the car

until bigger

The difference between the (F) step and the phase of adding

greater than

until less than

It may proceed to step (G) of subtracting .

Here, when the composite image E is generated in 3D, it may proceed based on the following equation.

는 Phase이고, n개의 위상으로 이동하여

번째 프린지 패턴이 된다.Here, the interval between the bright part and the dark part is defined as I period, and the brightness value I(x,y) at the position (x,y) of the object is

is a Phase, and by moving to n phases,

It becomes the second fringe pattern.

In the table below, the pixels around the pixel (x,y) for calculating the reliability R of the pixel (x,y) are as follows.

This phase spreading algorithm calculates the reliability R of each pixel by calculating the reciprocal of the sum S of the neighboring pixels and the second derivative.

는 각 픽셀의 위상 값이고,

은 연속한 픽셀의 위상 값 간의 위상 불연속성을 제거하는 위상 펼침 계산을 나타낸다.Here, H is the horizontal direction, V is the vertical direction, and D is the differential value in the diagonal direction.

is the phase value of each pixel,

denotes a phase spread calculation that removes the phase discontinuity between phase values of successive pixels.

의 역수로 각 픽셀의 신뢰도를 계산한다.The above calculation is performed for each pixel,

Calculate the reliability of each pixel as the reciprocal of .

To determine the phase unfolding path, first, the sum of the reliability of neighboring pixels in the horizontal and vertical directions is calculated, and the phase unfolding is performed from the interface with the largest sum of reliability.

And when a composite image (E) is created in 3D, the reliability R is calculated for all pixels (excluding the border) in (A) step, (B) only the reliability is collected for the boundary (B), and the reliability value is arranged in descending order for the boundary After step (C) and step (C), only the reliability of the boundary is collected and the pixels belonging to a small area are phase-expanded, and then the two areas are merged (D-1), when both pixels do not belong to the area Either step (D-2) of forming a new area by phase-extending for both pixels or step (D-3) of including pixels not belonging to the area in the area when only one pixel belongs to the area can After that, it may proceed to step (E) in which all borders are performed and borders are performed last.

The controller unit 30, which generates a composite image through the above-mentioned formula and process, can generate a composite image (E) by reflecting the problematic situation in the field in real time, such as lighting sequence, frequency division, noise removal, etc. depending on the inspection target. have.

Hereinafter, the operation of the surface inspection system using the fringe metric method of the present invention will be described in detail with reference to FIGS. 6 to 13 .

However, in order for the description of the fringe metric method of the present invention to be concise and clear, based on the fringe lighting part of the second embodiment among the fringe lighting parts of the first, second and third embodiments, the present invention The operation will be described in detail.

6 is a view showing an operating state of the fringe lighting unit according to the second embodiment of FIG. 3, and FIGS. 7 to 9 are a fringe image obtained through a surface inspection system using a fringe metric method according to an embodiment of the present invention. And, it is an image obtained by converting and synthesizing the fringe image, and FIGS. 10 to 12 are views showing the operating state of the lighting module included in the fringe lighting unit of the third embodiment that operates according to different cycles. And FIG. 13 is a view showing a state in which a plurality of lighting modules are formed and operated as one lighting module group.

The fringe lighting unit 10 includes the first illumination 01 to the 16th illumination 16 as described above. The fringe lighting unit 10 may be operated according to the first to fourth phase signals output from the controller unit 30 .

The controller 30 applies a phase signal to the fringe lighting unit 10, turns on some of the plurality of lights for a set time, and then turns them off while operating. Here, the controller unit 30 moves the four lights to have a phase difference of 90 degrees as one cycle of phase shift, and the fringe lighting unit 10 turns on the lights at a phase difference of 90 degrees. Specifically, the controller 30 turns on the first illumination, the fifth illumination, the ninth illumination, and the thirteenth illumination at a phase angle of 0 degrees through the first phase signal, and the Turn on the 2nd illumination, 6th illumination, 10th illumination, and 14th illumination at phase angle, and 3rd illumination, 7th illumination, 11th illumination, and 15th illumination at a phase angle of 180 degrees through a 3rd phase signal turns on, and turns on the 4th illumination, the 8th illumination, the 12th illumination, and the 16th illumination at a phase angle of 270 degrees through the 4th phase signal. The configuration of the controller 30 can have a phase change in various configurations such as three lights and five lights in addition to the four lights shown in the figure, and the phase interval can be configured at an angle of 360 degrees/n in addition to 90 degrees. do.

That is, when the fringe lighting unit 10 receives the first phase signal, the controller 30 turns on the plurality of lights as shown in (a) of FIG. 6 and receives the second phase signal. As shown in (b) of FIG. 6, the plurality of lights is turned on, and when the third phase signal is received, the plurality of lights is turned on as shown in (c) of FIG. 6, and the fourth When a phase signal is received, a plurality of lights is turned on as shown in (d) of FIG. 6 .

The controller 30 causes the fringe lighting unit 10 to operate as described above, and as shown on the left side of FIG. 7 , C1, C2, C3, C4, C1, C2, C3, C4, C1, C2, C3, C4 … Four images with a phase difference of 90 degrees are successively acquired in the order of C1, C2, C3, and C4. Here, the first fringe image C1 is generated when the fringe lighting unit 10 is operated in the first phase, that is, the first illumination 01, the fifth illumination 05, the ninth illumination 09, and the thirteenth illumination ( 13) is turned on, it becomes a fringe image acquired by the camera unit 20 . And the second fringe image C2 is generated when the fringe lighting unit 10 is operated in the second phase, that is, the second lighting 02, the sixth lighting 06, the tenth lighting 10, and the 14th lighting 14 ) is turned on, it becomes a fringe image acquired by the camera unit 20 . And the third fringe image C3 is generated when the fringe lighting unit 10 is operated in the third phase, that is, the third illumination 03, the 7th illumination 07, the 11th illumination 11, and the 15th illumination 15 ) is turned on, it becomes the fringe image C3 acquired by the camera unit 20 . And the fourth fringe image C4 is generated when the fringe lighting unit 10 is operated in the fourth phase, that is, the fourth illumination 04, the 8th illumination 08, the 12th illumination 12, and the 16th illumination 16 ) is turned on, it becomes a fringe image acquired by the camera unit 20 .

In addition, the controller 30 aligns the plurality of first fringe images C1 in a row according to the time order, and arranges the first aligned images D1 as shown in FIGS. 7 (a) and 8 (a). ) is created. Then, the plurality of second fringe images C2 are arranged in a row according to time order to generate a second aligned image D2 as shown in FIGS. 7 (b) and 8 (b). Then, the synthesized image E is generated by synthesizing the generated first aligned image D1 and the second aligned image D2.

In addition, the controller 30 aligns the plurality of third fringe images C3 in a row in a chronological order, and as shown in FIGS. 7 (c) and 8 (c), the third aligned image ( D3) is created. Then, the plurality of fourth fringe images C4 are arranged in a row according to the time order to generate a fourth aligned image D4 as shown in FIGS. 7(d) and 8(d).

In addition, when the controller 30 generates the above-described first aligned image D1, second aligned image D2, third aligned image D3, and fourth aligned image D4, all of the generated aligned images by synthesizing to generate a composite image E as shown in FIG. 9 .

The controller 30 synthesizes a total of four aligned images, that is, the first aligned image D1 to the fourth aligned image D4, so that the height difference of the damaged portion existing in each aligned image can be grasped.

At this time, the controller 30 may make the crumpled portion marked with a red square of each alignment image of FIG. 8 clearly appear as a red square on the composite image of FIG. 9 .

Such a controller 30 changes the phase difference between the first phase signal to the fourth phase signal, turns on and off a plurality of lights by using the changed phase as one cycle, so that the above-described characteristics can be more clearly expressed. do.

As an example, the controller 30 may set one cycle to either λ as shown in FIG. 10 or λ/2 as shown in FIG. 11 or λ/4 as shown in FIG. 12 as one cycle. have. The control unit 30 may turn on the lighting at the same time in response to each set cycle. In addition, the controller 30 may turn on a plurality of lights at intervals of π/16 to π/4 in cycles of λ, λ/2 and λ/4 as an example of a phase difference set in each set period.

In addition, the controller 30 simultaneously turns on and turns off at least two lights belonging to the lighting module group, and then simultaneously turns off at least two lights that are located on the other side of the turned-off lights - It can be turned on. As an example, the controller 30 includes a first illumination 01 and a second illumination 02, a fifth illumination 05, a sixth illumination 06, and a ninth illumination, as shown in FIG. 13(a). The illumination 09 and the tenth illumination 10 and the thirteenth illumination 13 and the 14th illumination 14 may be simultaneously turned on and off within a period of λ/4. As shown in (b) of FIG. 13 , the controller unit 30 includes a first illumination 01 , a second illumination 02 , a third illumination 03 , and a 7th illumination 07 and an 8th illumination ( 08), the ninth illumination 09, and the 13th illumination 13, the 14th illumination 14, and the 15th illumination 15 may be simultaneously turned on and off within a period of λ/3.

According to the present invention, images with a phase difference are obtained at the same time by obtaining an image line by line, that is, a fringe image, and controlling the brightness, phase, and period of illumination for each individual line even for a moving test object. And by synthesizing the acquired images, it is possible to accurately detect a defect in the test object.

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those of ordinary skill in the art to which the present invention pertains will understand that the present invention may be embodied in other specific forms without changing the technology or essential features. will be able Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

1: Surface inspection system using fringe metric method
10, 10-1, 10-2: fringe lighting unit
11: Frame module 12, 12-1, 12-2: Light module
20: camera unit 30: control unit
A: Bottom surface B: Inspection object
C1: 1st fringe image C2: 2nd fringe image
C3: 3rd fringe image C4: 4th fringe image
D1: first alignment image D2: second alignment image
D3: 3rd alignment image D4: 4th alignment image
E: Composite image

Claims (5)

A test object ( B) a fringe lighting unit 10 for irradiating light;
a camera unit 20 for obtaining a fringe image by photographing the test object (B);
Controls a plurality of lights in nanosecond units at a set phase difference interval at a set period,
A first phase signal that turns on and then turns off the light located on the one side of the plurality of lights for a set time,
It is located on the other side of the lights turned on by the first phase signal and outputs a second phase signal that turns on the lights that are turned on by the same number as the number of lights turned on by the first phase signal and a controller unit 30 applied to the lighting module 12,
The control unit 30,
At least two lights are turned on and off at the same time, and then located on the other side of the turned-off lights to turn on at least two lights that are turned off at the same time,
Each time the first phase signal is output, the plurality of first fringe images C1 acquired by the camera unit 20 are arranged in a row according to the time sequence, and whenever the second phase signal is outputted, the camera unit 20 ) and a fringe image receiving module 310 for arranging a plurality of second fringe images C2 obtained in a row and column according to the time sequence;
A plurality of sequentially received first fringe images (C1) are arranged in a row to generate one first aligned image (D1), and a plurality of second fringe images (C2) are arranged in a row to form one second image (C2). 2 an alignment module 320 for generating an alignment image D2;
Surface using a fringe metric method, comprising a composite image generation module 330 that generates a composite image E by synthesizing the first aligned image D1 to the second aligned image D2 with a preset formula inspection system. The method of claim 1, wherein the controller 30,
A third phase signal that is located on the other side of the lights turned on by the second phase signal and turns on the lights that are turned off by the same number as the number of lights turned on by the second phase signal;
The fourth phase signal is located on the other side of the lights turned on by the third phase signal and sequentially turns on the lights that are turned off by the same number as the number of lights turned on by the third phase signal. A surface inspection system using a fringe metric method that repeatedly outputs. The method of claim 2, wherein the controller 30,
Each time the third phase signal is output, a third fringe image C3 is obtained, each time the fourth phase signal is output, a fourth fringe image C4 is obtained, and a plurality of first fringe images C1 to a plurality of fringe images C1 are obtained. Obtaining the fourth fringe image (C4),
A plurality of third fringe images (C3) are arranged in a row to generate one third aligned image (D3),
By arranging a plurality of fourth fringe images (C4) in a row, one fourth aligned image (D4) is generated,
A surface inspection system using a fringe metric method for synthesizing the first fringe image (C1) to the fourth fringe image (C4) to generate a composite image (E) representing the height difference of the surface. 4. The method of claim 3,
The fringe image receiving module 310,
Sequentially receiving a plurality of first fringe images (C1) to a plurality of fourth fringe images (C4) photographed by the camera unit 20,
The alignment module 320 is
A plurality of sequentially received third fringe images (C3) are arranged in a row to generate one third aligned image (D3), and a plurality of fourth fringe images (C4) are arranged in a row to form one second image (C4). A fourth aligned image (D4) is generated, and a plurality of fourth fringe images (C4) are arranged in a row to generate one fourth aligned image (D4),
Composite image generation module 330,
A surface inspection system using a fringe metric method for generating a composite image (E) by synthesizing the third aligned image (D3) to the fourth aligned image (D4) using a preset formula.
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