JP2018091692A - Surface inspection apparatus, surface inspection method, surface inspection program, and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface inspection device suitable for the inspection of an object to be inspected and capable of performing a uniform irradiation not generating a dark spot part that tends to occur in the center and the like.SOLUTION: A surface inspection device 101 includes: a hollow spreading part 1 having an opening part capable of containing an object 7 to be inspected; a first illumination part (first light source 2) for radiating light toward the spreading part 1 from the outside of the spreading part 1; a beam splitter 3 provided at an angle sloped to an optical axis of light scattered to an opening direction of the opening part from the object 7 to be inspected; a diffuser plate 4 provided in a direction reflected by the beam splitter 3 in which the light scattered to the direction of the opening from the object to be inspected is reflected by the beam splitter 3; and imaging part 5 for detecting the light which is scattered in the opening direction from the object 7 to be inspected and detecting the light transmitting the beam splitter 3.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a surface inspection apparatus and a surface inspection method. The present invention also relates to a surface inspection program relating to the surface inspection apparatus and the surface inspection method, and a computer-readable recording medium on which the surface inspection program is recorded.

  Conventionally, as a means for inspecting a surface state, many inspection techniques using various characteristics such as light reflection, scattering, absorption, polarization, and color have been disclosed and put into practical use. Since the characteristics of light change depending on the surface condition of the object to be inspected, it is necessary to grasp the optical behavior that can be mathematically analyzed with respect to the surface condition, etc., and to irradiate and detect the inspection light. Become.

  For example, in the inspection of an object to be inspected having a free-form surface such as a sphere, a cylinder, or an uneven surface, when light is incident from one direction, “incident angle = reflection angle”, which is a strong reflection only in a specific direction. Will produce light. Then, when inspecting the surface state of such an object to be inspected, strong light intensity is generated in a specific direction to the observation direction, while analysis including any direction is required, and accurate observation and Evaluation becomes difficult.

  For example, Patent Document 1 discloses an automatic inspection apparatus having a configuration in which a laser beam is irradiated on the surface of the bearing to be inspected and the bearing is rotated to move the irradiated portion over the entire surface of the bearing. ing. Further, in Patent Document 2, the holding portion has a support portion having a receiving groove formed in an annular shape along the rotating peripheral surface, and the receiving groove can accommodate the vicinity of the bottom of the spherical object. In addition, a surface inspection apparatus or the like that can roll a spherical object in a receiving groove and change the direction of the spherical object by rotating a support portion is disclosed. As described above, as a technique for inspecting an inspected object having a free-form surface, a technique for inspecting while moving the inspected object is disclosed.

  On the other hand, Patent Document 3 discloses an image appearance inspection apparatus provided with an illuminating device including a cylindrical light diffusing member and ring illumination, and discloses a technique capable of photographing even if there is an unevenness or a surrounding obstacle. Is.

Japanese Patent Laid-Open No. 11-83756 Japanese Unexamined Patent Publication No. 7-63539 JP2015-55569A

  Regarding the surface inspection of an object to be inspected such as a product member having a free-form surface, the conventional technique has the following problems because it is difficult to uniformly illuminate the surface.

  First, since the region that can be observed is limited to a very narrow region (point), a mechanism for rotating the sample as in Documents 1 and 2 is required to inspect the entire surface. Therefore, a long inspection time is required, and it is difficult to perform a plurality of inspections at a time. Further, even if an optical fiber is used as the light receiving unit, the viewing angle increases, so that the detection resolution cannot be reduced, and rotation of the object to be inspected is necessary. In addition, as in Patent Document 2, it is conceivable to arrange sensors (optical fibers or the like) forming a light receiving unit on a plurality of shafts such as a fan shape, but there is a limitation on the arrangement of the light receiving unit (imaging unit). There remains a problem that an effective detection range cannot be ensured, or the rotation of the object to be inspected is still necessary.

  Moreover, in the structure of patent document 3, the scattered light is irradiated with respect to free curved surfaces, such as an unevenness | corrugation, by using the illuminating device provided with the cylindrical light-diffusion member and ring illumination, and on a single optical axis. It is possible to perform observation with relatively few shadows even with the image pickup means provided in. However, as a result of investigations by the present inventors, it has been found that even when the same configuration as this is taken, a portion that becomes a dark spot that is difficult to irradiate scattered light occurs at the center of the opening side of the cylindrical light diffusing member. This is particularly noticeable when the object to be inspected is a sphere, and in the case of a sphere, in order to observe the vicinity of the apex, incident light from directly above the opening side is generated so that reflected light in that direction is generated. This is thought to be necessary.

  Under such circumstances, the present inventors provide a surface inspection apparatus and method suitable for inspecting an object to be inspected having a free curved surface including a sphere, and capable of homogeneous irradiation that does not generate a dark spot that tends to occur at the center or the like. With the goal. Furthermore, it aims at providing the surface inspection apparatus and method which can detect the defect which cannot be judged only with the observation image of the reflected / scattered light of the surface of a sphere.

  As a result of intensive studies to solve the above problems, the present inventor has found that the following inventions meet the above object, and have reached the present invention.

  That is, the present invention relates to the following inventions.

A surface inspection apparatus according to the present invention includes a hollow diffusion part that can contain an object to be inspected and has an opening,
A first illumination unit that emits light from outside the diffusion unit toward the diffusion unit;
A beam splitter provided at an angle inclined with respect to the optical axis of light scattered from the object to be inspected in the opening direction of the opening;
A diffusion plate provided in a direction in which light scattered from the object to be inspected and incident on a beam splitter is reflected by the beam splitter;
An imaging unit that detects light scattered from the object to be inspected in the opening direction and transmitted through the beam splitter. In addition to irradiation with diffused light from the diffusion part, this surface inspection apparatus irradiates the inspection object from the opening direction of the diffusion part via the diffusion plate and the beam splitter. It is possible to obtain an image that has been subjected to homogeneous irradiation in which a dark spot that tends to occur at the center of the captured image does not occur.

  In the surface inspection apparatus according to the present invention, in the surface inspection apparatus, light scattered in the opening direction from the object to be inspected is provided in a direction that transmits the beam splitter, and the beam splitter, the imaging unit, It is preferable to have a polarizing filter provided between the two. This surface inspection apparatus can obtain an image suitable for analysis based on the polarization component of the object to be inspected by the polarization filter.

  In the surface inspection apparatus according to the present invention, it is preferable that the surface inspection apparatus further includes a second illumination unit that irradiates light toward the beam splitter with respect to the diffusion plate. With the light from the second illuminating part, it is possible to perform uniform irradiation on the dark spot part generated in the opening direction of the diffusing part.

  In the surface inspection apparatus according to the present invention, it is preferable that the diffusion unit is a diffusion unit having a pattern portion of a predetermined color. Since the surface inspection apparatus projects the pattern of the predetermined color onto the object to be inspected, the shape of the object to be inspected can be clarified by analyzing the image of the object to be inspected on which the pattern is projected. It can be easily analyzed.

  The surface inspection apparatus according to the present invention is preferably an imaging unit in which, in the surface inspection apparatus, the imaging unit captures a plurality of detection images related to the intensity of light having a plurality of wavelengths. This surface inspection apparatus analyzes an image of an arbitrary color among images of a plurality of wavelengths of light (a plurality of colors) or compares a plurality of color images to determine color characteristics (color distribution, color unevenness, etc.) ) Is suitable for analyzing.

  The surface inspection apparatus according to the present invention preferably includes a polarization filter rotation unit for rotating the polarization filter and capturing polarization component images of at least three angles in the surface inspection apparatus. This surface inspection device is based on polarization components that obtain polarization component images at three angles, compare these images, accurately grasp the major axis of elliptically polarized light, and calculate its ellipticity. More detailed analysis can be performed.

  The surface inspection apparatus according to the present invention having such characteristics is particularly suitable for analysis of an inspection object having a free-form surface.

The surface inspection method according to the present invention includes the step of disposing the object to be inspected inside a hollow diffusion part that can contain the object to be inspected and has an opening;
Irradiating the diffusing portion from the outside by a first illumination unit irradiating light toward the diffusing portion from outside the diffusing portion; and
Separating the light incident on the beam splitter by a beam splitter provided at an angle inclined with respect to the optical axis of the light scattered in the opening direction of the opening from the inspection object;
The light incident on the diffusion plate is reflected by the diffusion plate provided in a direction in which the light scattered from the object to be inspected in the opening direction and reflected on the beam splitter is reflected. Irradiating the object to be inspected from the opening side;
And imaging with an imaging unit that detects the light scattered from the object to be inspected in the opening direction and transmitted through the beam splitter and captures it as an image.
In this surface inspection method, in addition to irradiation with diffused light from the diffusion part, the object to be inspected is also irradiated from the opening direction of the diffusion part via the diffusion plate and the beam splitter. It is possible to obtain an image that has been subjected to homogeneous irradiation in which a dark spot that tends to occur at the center of the captured image does not occur. In addition, the surface inspection apparatus according to the present invention described above can be used in the surface inspection method according to the present invention, and achieves a more preferable inspection method corresponding thereto by performing a process corresponding to each suitable configuration. be able to.

In the surface inspection method according to the present invention, in the surface inspection method, an image for each predetermined pixel can be captured in the imaging step, and an inspection range of the object to be inspected from the image captured in the imaging step A luminance image analysis step for determining the luminance of each pixel in the inspection range,
In the luminance image analysis step, a luminance for each pixel of a standard sample as the object to be inspected, a standard luminance distribution analysis step for obtaining a threshold value based on a luminance distribution for each pixel of the standard sample,
The luminance image analysis step determines the luminance for each pixel of the test sample as the object to be inspected, and the luminance abnormality for specifying the luminance abnormality point of the test sample by comparing with the threshold value obtained by the standard luminance distribution analysis step A point identification process;
The abnormal luminance point range in which the abnormal luminance points specified by the abnormal luminance point specifying step are close to each other is obtained, and the abnormal luminance point of the test sample is determined by a combination parameter of the abnormal luminance point range and the luminance of the abnormal luminance point. A luminance abnormality point analysis step for scoring the distribution,
It can be set as the method of analyzing a brightness nonuniformity based on the score by the said brightness | luminance abnormal point analysis process. According to this surface inspection method, luminance unevenness of a test sample as an object to be inspected can be scored and analyzed, and if an image is detected as luminance of light having a specific wavelength, light having that wavelength can be analyzed. It is also possible to analyze color unevenness corresponding to.

  In the surface inspection method according to the present invention, in the inspection method, light scattered in the opening direction from the object to be inspected is provided in a direction that passes through the beam splitter, and the surface splitter includes the beam splitter and the imaging unit. It is preferable to have a step of polarization separation using a polarizing filter provided therebetween. This surface inspection apparatus can obtain an image suitable for analysis based on the polarization component of the object to be inspected by the polarization filter.

The surface inspection method according to the present invention is the surface inspection method,
An image for each predetermined pixel can be captured in the imaging step, the inspection range of the inspection object is specified from the image captured in the imaging step, and a polarization component for each pixel in the inspection range is determined. A polarization component image analysis step to be obtained,
By the polarization component image analysis step, a polarization component distribution analysis step for obtaining a polarization component for each pixel of the standard sample as the object to be inspected, and obtaining a threshold value based on a polarization component distribution for each pixel of the standard sample;
By the polarization component image analysis step, a polarization component for each pixel of the test sample is obtained as the object to be inspected, and the polarization component abnormality point of the test sample is compared with the threshold value obtained by the standard polarization component distribution analysis step. A polarization component abnormal point identifying step to identify;
A polarization component abnormal point range in which the polarization component abnormal points specified by the polarization component abnormal point specifying step are close to each other is obtained, and the test is performed based on a combination parameter of the polarization component abnormal point range and the polarization component of the polarization component abnormal point. A polarization component abnormal point analysis step for scoring the distribution of polarization component abnormal points of the sample,
It can be set as the method of analyzing a polarization component nonuniformity based on the score by the said polarization component abnormal point analysis process. According to this surface inspection method, it is possible to analyze the polarization component unevenness of the test sample as the inspection object. The polarization component image is obtained by rotating the polarization filter with a polarization filter rotating means or the like, obtaining polarization component images at a plurality of (preferably 3 or more) polarization filter angles, and analyzing the polarization component images. Analysis can be performed.

In the surface inspection program according to the present invention, the object to be inspected can be included in a hollow diffusion part having an opening, and the inspection object is arranged from outside the diffusion part toward the diffusion part. The diffusion unit is irradiated from the outside by a first illumination unit that irradiates light, and the beam splitter provided at an angle inclined with respect to the optical axis of light scattered in the opening direction of the opening from the object to be inspected. The light incident on the beam splitter is separated, and the light incident on the diffusion plate by the diffusion plate provided in the direction in which the light incident on the beam splitter after being scattered from the object to be inspected is reflected. And irradiating the object to be inspected from the opening side through the beam splitter, and detecting light scattered from the object to be inspected and transmitted through the beam splitter. Using the image captured by the imaging unit for imaging as,
A luminance image analysis means for specifying an inspection range of the object to be inspected from the captured image and obtaining a luminance for each pixel of the inspection range;
The luminance image analysis means obtains the luminance for each pixel of the standard sample as the object to be inspected, and the standard luminance distribution analysis means obtains a threshold value based on the luminance distribution for each pixel of the standard sample,
The luminance image analysis means determines the luminance of each pixel of the test sample as the object to be inspected, and compares the threshold obtained by the standard luminance distribution analysis means with the luminance abnormality point of the test sample. Point identification means;
A luminance abnormal point range in which the abnormal luminance points specified by the abnormal luminance point specifying means are close to each other is obtained, and a luminance abnormal point range of the test sample is determined by a combination parameter of the abnormal luminance point range and the luminance of the abnormal luminance point. The luminance abnormality point analysis means for scoring the distribution can be a surface inspection program for causing a computer to execute. This surface inspection program is for achieving an image captured by the surface inspection apparatus according to the present invention as a surface inspection method for analyzing luminance unevenness according to the present invention.

In the surface inspection program according to the present invention, the object to be inspected can be included in a hollow diffusion part having an opening, and the inspection object is arranged from outside the diffusion part toward the diffusion part. The diffusion unit is irradiated from the outside by a first illumination unit that irradiates light, and the beam splitter provided at an angle inclined with respect to the optical axis of light scattered in the opening direction of the opening from the object to be inspected. The light incident on the beam splitter is separated, and the light incident on the diffusion plate by the diffusion plate provided in the direction in which the light incident on the beam splitter after being scattered from the object to be inspected is reflected. The object to be inspected is irradiated from the opening side through the beam splitter, scattered from the object to be inspected and transmitted through the beam splitter, and the object to be inspected. Imaging in which light scattered in the direction of the aperture is provided in a direction that passes through the beam splitter, and the light separated by the polarization filter provided between the beam splitter and the imaging unit is detected and captured as an image Using the image captured by the
A polarization component image analyzing means for specifying a test range of the test object from the captured image and obtaining a polarization component for each pixel of the test range;
The polarization component image analysis means obtains a polarization component for each pixel of the standard sample as the object to be inspected, and a standard polarization component distribution analysis means for obtaining a threshold value based on the distribution of the polarization component for each pixel of the standard sample;
The polarization component image analysis means obtains the polarization component for each pixel of the test sample as the object to be inspected, and compares the polarization component abnormality point of the test sample with the threshold value obtained by the standard polarization component distribution analysis means. Means for identifying the polarization component abnormal point to be identified;
A polarization component abnormal point range in which the polarization component abnormal points specified by the polarization component abnormal point specifying unit are close to each other is obtained, and the test is performed according to a combination parameter of the polarization component abnormal point range and the polarization component of the polarization component abnormal point. A polarization component abnormal point analysis means for scoring the distribution of the polarization component abnormal points of the sample can be used as a surface inspection program for causing a computer to execute. This surface inspection program is for achieving an image captured by the surface inspection apparatus according to the present invention as a surface inspection method for analyzing polarization component unevenness according to the present invention. It can also be set as the computer-readable recording medium which recorded these surface inspection programs.

  The surface inspection apparatus and the surface inspection method of the present invention are suitable for inspecting an object to be inspected having a free curved surface including a sphere, thereby performing imaging with uniform irradiation that does not generate a dark spot portion that tends to occur at the center of the object to be inspected. It becomes possible.

BRIEF DESCRIPTION OF THE DRAWINGS It is a whole schematic diagram for demonstrating 1st embodiment of the surface inspection apparatus which concerns on this invention. It is a whole schematic diagram for demonstrating 2nd embodiment of the surface inspection apparatus which concerns on this invention. It is a whole schematic diagram for demonstrating 3rd embodiment of the surface inspection apparatus which concerns on this invention. It is a whole schematic diagram for demonstrating 4th embodiment of the surface inspection apparatus which concerns on this invention. It is a schematic diagram of the spreading | diffusion part for describing 5th embodiment of the surface inspection apparatus which concerns on this invention. It is a figure for demonstrating imaging of the to-be-inspected object by the spreading | diffusion part of 5th embodiment of the surface inspection apparatus which concerns on this invention. It is a figure for demonstrating other imaging of the to-be-inspected object by the spreading | diffusion part of 5th embodiment of the surface inspection apparatus which concerns on this invention. It is a figure for demonstrating imaging of the to-be-inspected object by the other spreading | diffusion part of 5th embodiment of the surface inspection apparatus which concerns on this invention. It is a figure which shows the flow of 6th embodiment of the surface inspection method which concerns on this invention. It is a figure which shows the flow of 7th embodiment of the surface inspection method which concerns on this invention. It is a whole schematic diagram for demonstrating 8th embodiment of the surface inspection apparatus of this application. It is a figure for demonstrating the example of the surface nonuniformity analysis based on 8th embodiment. It is the figure which imaged the iron ball by the example of the surface inspection device concerning the present invention. It is the figure which imaged the iron ball by other examples of the surface inspection device concerning the present invention. It is the figure which analyzed the iron ball imaged with the other Example of the surface inspection apparatus which concerns on this invention.

  DESCRIPTION OF EMBODIMENTS Embodiments of the present invention will be described in detail below. However, the description of constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention will be described below unless the gist thereof is changed. It is not limited to the contents.

(First embodiment of the present invention)
FIG. 1 shows an outline of the overall configuration of the first embodiment of the surface inspection apparatus according to the present invention. The surface inspection apparatus and the surface inspection method using the same will be described. The surface inspection apparatus 101 includes a diffusing unit 1, a first light source 2, a beam splitter 3, a diffusing plate 4, and an imaging unit 5. Furthermore, the surface inspection apparatus 101 includes an image detection unit 81, an image analysis unit 82, and a display unit 83 in order to appropriately display and analyze an image captured by the imaging unit 5.

  In this surface inspection apparatus 101, the diffusing unit 1 is a cylindrical body, and is arranged in a state where the inspection object 7 is included in the cylinder, and the surface of the inspection object 7 is inspected. And the 1st light source 2 turns into a 1st illumination part which irradiates light from the outer side of the spreading | diffusion part 1 to the spreading | diffusion part 1 direction. The irradiated light is transmitted while being diffused by the diffusing unit 1, and further diffused in the diffusing unit, so that the inspected object 7 arranged in the diffusing unit is irradiated with light having various incident angles. By being in the state, light irradiation from an incident angle exceeding the simple positional relationship between the first light source 2 and the inspection object 7 is performed. This also irradiates the surface of the inspection object having a free-form surface with light having various incident angles.

  A part of the light irradiated to the inspection object 7 is reflected (scattered) in the direction of the beam splitter 3 provided in the direction of the opening of the diffusing unit 1 in FIG. The beam splitter 3 is arranged such that the light separation surface is inclined with respect to the optical axis of the reflected light (scattered light) from the object to be inspected. Preferably, the optical axis of the reflected light from the object to be inspected and the surface on which the beam splitter 3 separates the light form 45 °. The light incident on the beam splitter 3 is transmitted through the beam splitter 3 according to the angle formed between the optical axis of the light reflected from the object to be inspected and the beam splitter 3, and the objective lens 51. Is detected by the imaging unit 5. On the other hand, of the light incident on the beam splitter 3, the light that has not been transmitted in the direction of the imaging unit (reflected light) is further reflected by the beam splitter 3 according to their positional relationship.

  A diffusion plate 4 is disposed on the optical axis of the light reflected from the beam splitter 3. The diffusion plate 4 further diffuses and reflects the light reflected from the beam splitter 3. The light diffused / reflected from the diffusion plate 4 is incident on the beam splitter again, reflected by the beam splitter 3, and enters the diffusion unit 1 from the opening side of the diffusion unit 1. Irradiation is performed from above in FIG. And when the light irradiated to the to-be-inspected object 7 from the opening side through this diffusion plate 4 and the beam splitter 3 is reflected from the to-be-inspected object 7, the first light source 2 and the diffusing part 1 described above. The light 7 is incident (transmitted) on the beam splitter 3 again from the opening side like light reflected on the inspection object 7 through the object 7, and the light having the predetermined intensity is detected by the imaging unit 5.

  Since the light irradiated from the first light source 2 irradiates the inspected object 7 through the diffusing unit 1, the inspected object 7 is irradiated with light having incident angles in almost all directions. Therefore, the first light source 1 and the shape and arrangement of the object to be inspected 7 are less affected, but the opening side of the diffusing unit 1 has a blind spot (dark spot without incident light). Part, dark spot). Since the beam splitter 3 and the diffusing plate 4 are arranged in a direction that tends to be a blind spot, light having various incident angles is irradiated from the opening side as described above. With such a configuration, the inspection object 7 can be observed without a blind spot on the opening side of the diffusing unit 1, and the imaging unit 5 is imaged in a state where light is omnidirectionally applied to the inspection object 7. Can be detected.

  An image picked up by the image pickup unit 5 (detected scattered light) can be detected by the image detecting means 81 as it is or by appropriately selecting or synthesizing it and analyzed by the image analyzing means 82. The analysis result is displayed on the display unit 83 as appropriate. Further, each detecting means and analyzing means can appropriately read out parameters and calculation formulas stored in advance in a storage unit (not shown), and can store detected images and analysis results in this storage unit.

  The inspected object 7 to be subjected to the surface inspection according to the present invention can be various objects. In particular, an object to be inspected having a free-form surface and an object to be inspected having a high light reflectance can be targeted. For example, it is suitable for inspection of a metal or the like having a high reflectivity, or a sphere or irregularity that causes remarkably inhomogeneous reflection or shadow when irradiated from one direction.

  The diffusing unit 1 is designed to have a size that can accommodate a size of the inspection object 7. The diffusion portion 1 is formed of a material having light scattering properties and light transmission properties. Further, it is preferable to use a white material so as not to be affected by the wavelength of light. As such a material, for example, a white plastic material or paper is used. More specifically, examples include those obtained by forming a light diffusing sheet or white paper used for optical applications into a cylindrical shape, and those obtained by forming a foamed plastic into a hollow cylindrical shape. The diffusing unit 1 only needs to have an opening in the direction in which the beam splitter, the imaging unit, and the like are arranged so as to sufficiently wrap the object to be inspected. A dome-like shape can also be used.

  The diffusion part 1 is provided with an opening. In the direction of the opening, a beam splitter 3, an imaging unit 5, and the like are arranged. Scattered light is scattered from the inside of the diffusing unit 1 toward the opening. For example, a part of the scattered light from the inspected object 7 and the like in the diffusing unit 1 is scattered out of the diffusing unit 1 from this opening. The size of the opening is appropriately designed according to conditions such as the degree of light irradiation by the configuration of the object 7 to be inspected, the diffusing unit 1, the diffusing plate 4, etc., and the range in which imaging can be performed according to the positional relationship with the imaging unit 5. When the diffusing portion is cylindrical, it may be handled as an opening in an open state where there is no lid on the end side of the tube, or may be an opening by providing a hole in the lid. In the case of a dome-shaped diffusion portion, a hole may be provided to form an opening. The direction in which the opening is provided is set by the position where the beam splitter 3 and the like are arranged. Alternatively, a beam splitter or the like may be arranged in accordance with the position of the opening. The image is taken by the imaging unit 5 from the opening direction. At this time, the portion extending from the imaging direction of the imaging unit 5 to the extending direction of the opening so that the boundary between the object to be inspected and other than the object to be inspected becomes clear. (For example, a cylindrical portion corresponding to the bottom when the lid side is an opening) may have a black configuration in which light is hardly scattered (for example, black paper is disposed). These black areas are designed in such a range that incident light is not incident on the surface of the object 7 to be inspected from the direction of the imaging unit 5.

  In the first embodiment, the first light source 2 is a first illumination unit that emits light in the direction of the diffusion unit 1 from the outside of the diffusion unit 1. As such a light source, arbitrary light for observing the inspection object 7 can be selected, but a white light source is generally adopted. In the present invention, light is diffused by the diffusing unit 1, but light having low directivity is preferably used so as to be more easily diffused. Moreover, you may irradiate with the light bulb and surface irradiation body which irradiate light from one side of the spreading | diffusion part 1, and you may use the ring-shaped light source which covers a spreading | diffusion part.

  The beam splitter 3 divides (separates) the light incident on the beam splitter 3, and part of the incident light is reflected and part of the light is transmitted. There are so-called half mirrors. By disposing the beam splitter 3 in the oblique direction on the opening side, a part of the light scattered from the diffusion part (light scattered in the opening part direction from the inspection object 7) is directed to the imaging part side. A part of the light is reflected depending on the incident angle, and the diffusion plate 4 is arranged in the reflection direction.

  The diffusion plate 4 diffuses and reflects the light reflected from the beam splitter 3. The diffusion plate 1 may be made of the same material as the diffusion unit 1. The main function of the diffuser plate is to reflect the light reflected by the beam splitter to the beam splitter side. Therefore, it is preferable to use a plate-like plate that can reflect light at an incident angle with respect to the diffuser plate as it is. .

  The imaging unit 5 detects light that has passed through the beam splitter 3 out of light scattered from the inside of the diffusion unit 1 such as light reflected from the inspection object 7. Moreover, in the surface inspection apparatus 101 shown in FIG. 1, the objective lens 51 etc. can be arrange | positioned so that the transmitted light may be detected easily. For the imaging unit 5, a pixel corresponding to the purpose of the surface inspection, a camera capable of detecting a color, or the like is used. For example, a CCD camera or the like is employed.

  The image captured by the imaging unit 5 can be simply evaluated by displaying the captured image on a display unit or the like. Further, if necessary, further optical processing and image processing according to the purpose can be performed and inspected by the image detection means 81 and the image analysis means 82.

(Second embodiment of the present invention)
FIG. 2 shows an outline of the overall configuration of the second embodiment of the surface inspection apparatus according to the present invention. The surface inspection apparatus and the surface inspection method using the same will be described. The surface inspection apparatus 102 includes a diffusion unit 1, a first light source 2, a beam splitter 3, a diffusion plate 4, an imaging unit 5, and a polarizing filter 6. Further, the surface inspection apparatus 102 includes an image detection unit 81, an image analysis unit 821, and a display unit 83 in order to appropriately display and analyze an image captured by the imaging unit 5.

  In the second embodiment, the same inspection as that of the first embodiment is performed, and in addition to the same inspection, the light is scattered from the diffusion unit 1 in the opening direction of the diffusion unit 1 and transmitted through the beam splitter 3. The polarizing filter 6 is provided between the beam splitter 3 and the imaging unit 5 (objective lens 51). By providing the polarizing filter 6, a polarization component corresponding to the polarizing filter 6 is detected by the imaging unit 5. As the polarizing filter 6, various polarizing filters such as a linearly polarizing plate, an elliptically polarizing plate, and a polarizing beam splitter can be used. By providing this, it is possible to inspect the surface of the inspection object 7 based on the polarization component. It becomes.

  Further, the polarizing filter 6 preferably includes a polarizing filter rotating means (not shown). As the object 7 to be inspected, an object having a free-form surface (typically a sphere) can be adopted as an inspection object. Here, the light reflected from the object to be inspected having a free-form surface often has an irregular angle of the polarization component, and is generally used when inspecting the polarization component. In some cases, it is difficult to inspect based on the polarization component in which the angle of p-polarized light and s-polarized light is grasped in advance and the polarizing filter is set.

  For this reason, it may be important to grasp the state of polarization such that the polarization component of the light reflected from the inspected object 7 is assumed to be elliptically polarized at an arbitrary angle. For this purpose, it is effective to rotate the polarizing filter about the optical axis incident on the imaging unit by the rotating means and acquire the polarization component detected by transmitting through the polarizing filter arranged at a plurality of angles. . For example, if the initial arrangement of a polarizing filter, which is a linear polarizing plate, is 0 °, polarization components of at least three angles are acquired, such as when this is rotated 90 ° and when it is rotated 45 °. Then, based on these results, it is possible to analyze the ellipse major axis direction as the elliptically polarized light of the reflected light of the object to be inspected 7 to grasp the distribution, and further to obtain the ellipticity. The image analysis unit 821 is an analysis unit that can also perform analysis regarding such a polarization component.

(Third embodiment of the present invention)
FIG. 3 shows an outline of the overall configuration of the third embodiment of the surface inspection apparatus according to the present invention. The surface inspection apparatus and the surface inspection method using the same will be described. The surface inspection apparatus 103 includes a diffusion unit 1, a first light source 2, a beam splitter 3, a diffusion plate 4, an imaging unit 5, a polarization filter 6, and a second light source 41. Furthermore, in the surface inspection apparatus 103, as in the second embodiment, in order to appropriately display and analyze the image captured by the imaging unit 5, an image detection unit 81, an image analysis unit 821, and a display unit 83.

  The third embodiment has a second light source 41 in addition to the same inspection performed by the configuration common to the first embodiment and the second embodiment. The second light source 41 irradiates the diffusion plate 4 with light in the direction of the beam splitter 3. That is, the second light source 41 scatters from the opening of the diffusing unit 1 and reflects the beam splitter 3 of the diffusing plate 4 with respect to the diffusing plate 4 provided on the reflection angle of the light reflected by the beam splitter 3. Place on the opposite side of the side.

  The light emitted from the second light source 41 is diffused by the diffusion plate 4 and transmitted to the beam splitter 3 side. As described in detail in the first embodiment, the diffusion plate 4 diffuses and reflects the light reflected by the beam splitter 3 so that the light is incident again on the beam splitter 3 through the diffusion plate 4. The re-incident light is reflected by the beam splitter 3 and irradiates the inside of the diffusing unit 1 and the inspection object 7 from the opening side of the diffusing unit 1. The light reflected from the beam splitter 3 and irradiated through the diffusion plate 4 through re-incident is originally derived from the first light source 2, and the illuminance is reduced by attenuation or the like due to multiple times of diffusion and reflection. It tends to be easy to do. For this reason, the light irradiated to the dark spot part by the side of an opening part may become inadequate.

  In order to eliminate this dark spot part, it is effective to provide a second illumination part. As this 2nd illumination part, the 2nd light source 41 is provided in 3rd embodiment. The light emitted from the second light source 41 is diffused and transmitted by the diffusion plate 4 as described above, enters the beam splitter 3, and irradiates the inside of the diffusion unit 1 from the opening side of the diffusion unit 1. Thereby, it is easy to secure sufficient irradiation intensity for incident light from the opening side, and a dark spot portion is hardly generated. Further, by providing the first light source 2 and the second light source 41, it is easy to adjust the light irradiation according to the diffusing unit 1, the inspection object 7 and the like. On the other hand, both the first light source 2 and the second light source 41 maintain the design in which the light is diffused and irradiates the object 7 to be inspected. The problem of being can be sufficiently reduced.

(Fourth embodiment of the present invention)
FIG. 4 shows an outline of the overall configuration of the fourth embodiment of the surface inspection apparatus according to the present invention. The surface inspection apparatus and the surface inspection method using the same will be described. The surface inspection apparatus 104 includes a diffusing unit 1, a first light source 2, beam splitters 3 and 31, a diffusing plate 4, an imaging unit 5, a polarizing filter 6, and a reflecting mirror 42. Furthermore, the surface inspection apparatus 104 includes an image detection unit 81, an image analysis unit 821, and a display unit 83 in order to appropriately display and analyze an image captured by the imaging unit 5. The fourth embodiment is a modification of the third embodiment having the second illumination unit.

  In 3rd embodiment, it was set as the structure which uses the 2nd light source 41 as a 2nd illumination part. On the other hand, in the fourth embodiment, a beam splitter 31 is also provided on the optical axis of the first light source 1 to separate the light before entering the diffusing unit 1. One of the separated lights (for example, transmitted light) irradiates the diffusing part as it is, and thus functions as a first illumination part. The other (for example, reflected light) of the separated light is provided with a reflecting mirror 42 in the reflecting direction, further reflects the light, and irradiates the beam splitter 3 side through the diffusion plate 4. It functions as a second illumination unit. In this way, the light source itself can achieve the first illumination unit and the second illumination unit as the first light source 2 alone by designing the optical system thereafter.

  When the illumination in the fourth embodiment is performed, since the original light source is the same, it is possible to improve the homogeneity between the irradiation having a large influence by the diffusion unit 1 and the irradiation having a large influence through the diffusion plate 4. . Therefore, color unevenness derived from the light source can be further reduced. When a plurality of light sources are used, even if the products have the same specifications, the color and brightness may be slightly different, so the effect of the illumination system using such a same light source is great.

(Fifth embodiment of the present invention)
FIG. 5 shows an outline of the configuration of the diffusing section for explaining the fifth embodiment of the surface inspection apparatus according to the present invention. This diffusion unit can be applied to any of the first to fourth embodiments described above, and can be implemented using the diffusion unit 11 instead of the diffusion unit 1. The diffusion part 11 is provided with a black line part 11b inside the diffusion cylinder 11a. The black line portion 11b is provided with regularity in eight equal directions around the circle at the bottom of the cylindrical diffusion tube 11a. Further, the black line portion 11b is provided in a straight line shape in the height direction of the cylinder.

  Here, as an example of the pattern of the predetermined color, the diffusing unit 11 in which linear lines (black line portions 11b) provided in the vertical direction in the height direction of the cylinder are provided at predetermined intervals is exemplified. It is good also as a thing. For example, in addition to the upper and lower lines in the height direction, lines may be drawn at predetermined heights in the circumferential direction of the cylinder that goes directly to it, and it may be a lattice shape, for analysis of the shape of the object to be inspected etc. Any valid pattern can be set.

  The colors of these patterns may be changed as appropriate, and arbitrary colors may be adopted. For example, it is possible to adopt an image pickup unit that can pick up a plurality of colors such as RGB, obtain a pattern image only for a predetermined color, and simultaneously pick up each image with or without a pattern. The black line is easy to adopt because it is easy to confirm the pattern clearly in any color image. Such a predetermined color pattern is preferably provided inside the diffusion portion. If it is provided outside the diffusion tube, the pattern of the color may be diffused by the inner diffusion part and a clear pattern may not be reflected on the object to be inspected.

  6 and 7 are diagrams for explaining an example of imaging when the diffusing unit 11 of the fifth embodiment is arranged in place of the diffusing unit 1 of the first embodiment. A case where a surface inspection is performed using an inspection ball 71 as an inspection object will be described as an example.

  As shown in FIG. 6 (a), when the inspected sphere 71 is arranged in the approximate center of the diffusing unit 11 and the surface inspection is performed, an image captured by the imaging unit 5 is as shown in FIG. 6 (b). An image like the image 71a of the inspected sphere 71 is obtained. The black line 11c is confirmed in the image 71a by reflecting the line of the black line portion 11b. That is, an image in which a pattern by the black line portion 11b is projected is obtained, and by analyzing this pattern, it is possible to easily analyze the sphericity of the inspected sphere 71, distortion, the presence or absence of dents, and the like. When the sphericity is high, the black line 11c is a uniform straight line and radiates from the center of the image 71a. On the other hand, when the sphericity is low, the line is partially curved. In addition, when there are dents or scratches, distortion occurs.

  In addition, since the pattern provided in this diffusion part 11 does not have a pattern (black line part 11b) in the part corresponding to the opening part of the diffusion part 11, the line corresponding to it does not appear in the image 71a. In order to perform a more stable inspection, a pedestal for arranging the inspected object 71 may be provided corresponding to the center of the diffusing unit 11.

  On the other hand, as shown in FIG. 7 (a), when the inspected sphere 71 is placed at a position shifted from the approximate center of the diffusing unit 11 and the surface inspection is performed, the image captured by the imaging unit 5 is as shown in FIG. An image such as an image 71b of the inspected sphere 71 as shown in b) is obtained. In this case, the center corresponding to the opening and the black line 11c due to the black line portion 11b are slightly deviated from the center of the image 71b. However, it still appears as a straight line, and an analysis in which the deviation between the inspected sphere 71 and the diffusing unit 11 is also corrected can be performed from the pattern. The object to be inspected may be an object such as the inspected sphere 71, but in the case of such a sphere, it may roll within the diffusing unit 11 and be difficult to dispose at the center and may be displaced. . The cylindrical diffusion portion is excellent in that a sufficient surface inspection can be performed by image analysis as it is even if such a shift occurs.

  FIG. 8 illustrates a case where the shape of the diffusion portion in the fifth embodiment is changed. Here, the diffusion part 12 is formed by a dome-shaped diffuser 11d. The case where the black line portion 11e is provided in the dome-shaped diffuser and the inspected sphere 71 is arranged therein to perform the surface inspection will be described as an example. When the diffusing unit 12 is a dome-shaped diffuser, and the inspected sphere 71 is displaced from the center of the diffusing unit 12, the pattern of the black line portion 11e is curved in the image 71c obtained by imaging the inspected sphere 71. appear. In this case, it is difficult to determine whether the pattern generated in the curved shape is due to the sphericity or the like of the inspected sphere 71 or due to the displacement of the arrangement, and the image analysis may be complicated. In order to eliminate this, it is necessary to accurately place the ball 71 to be inspected at the center with respect to the diffusing portion 12 having a dome shape.

(Sixth embodiment of the present invention)
An analysis method related to the surface inspection of the present invention will be described with reference to FIGS. 9 and 10 as appropriate. According to the present invention, the apparatus configuration of the first embodiment described above includes the step of disposing the object to be inspected inside a hollow diffusion part that can contain the object to be inspected and has an opening, and the diffusion part. A step of irradiating the diffusion part from the outside by a first illumination part that irradiates light toward the diffusion part from outside, and an optical axis of light scattered from the object to be inspected in the opening direction of the opening part. A step of separating light incident on the beam splitter by a beam splitter provided at an inclined angle, and diffusion provided in a direction in which the light scattered from the object to be inspected and reflected on the beam splitter is reflected A step of reflecting light incident on the diffusion plate by the plate to the beam splitter and irradiating the object to be inspected from the opening side through the beam splitter; and from the object to be inspected in the opening direction Disturbed can be a surface inspection method and a step of imaging by the imaging unit that captures the detected image light transmitted through the beam splitter.

  The analysis of the image picked up by this surface inspection can be performed as follows, for example. First, in order to perform this analysis, in an imaging process, imaging for capturing an image for each predetermined pixel is performed to obtain an image having information for each pixel. Then, a luminance image analysis step is provided in which the inspection range of the object to be inspected is specified from the image captured by such an imaging step, and the luminance of each pixel in the inspection range is obtained. More specifically, for example, by adopting a CCD camera or the like that exceeds 100 × 100 pixels as the imaging means, and when the object to be inspected is spherical or circular, as a two-dimensional image thereof, It is set as the structure which can specify a to-be-inspected object part by this circle. Note that the luminance here may be analyzed as white light equivalent or luminance of only a specific wavelength and analyzed as a whole luminance unevenness, or by detecting a plurality of images related to the intensity of light of a plurality of wavelengths. The luminance corresponding to an arbitrary color may be selectively analyzed or compared and analyzed as color unevenness.

  Then, a standard luminance distribution analyzing step for determining a threshold value based on the luminance distribution of the standard sample is performed by the luminance image analyzing step (S1 in FIG. 9). Basically, the standard sample is a sample equivalent to a non-defective product that is a standard such as an ideal sample to be inspected or a limit sample. First, such a standard sample is imaged, and the luminance image is analyzed by the luminance image analyzing step as described above (S11). Then, a threshold value based on the luminance distribution of the standard sample is determined (S12). As a method for determining a threshold value based on the luminance distribution, for example, an average value of luminance values of pixels in the inspection range of the standard sample (any average value can be adopted according to the purpose) is obtained, and the average value is obtained. By defining an allowable range for, a value that becomes a threshold value of the allowable range can be set as the threshold value. That is, the threshold value can be set such that the standard deviation σ of the luminance of the inspection range of the standard sample is set as the allowable range, and “average luminance value ± standard deviation σ” is set within the threshold range. Depending on a specific standard sample, a threshold value may be set as “average luminance value ± standard deviation 3σ” or “average luminance value ± standard deviation 6σ”.

  Next, the luminance image analysis step determines the luminance of each pixel of the test sample, and identifies the abnormal luminance point of the test sample by comparing with the threshold value obtained by the standard luminance distribution analysis step (S1 in FIG. 9). A luminance abnormal point identifying step is performed. And a luminance abnormality point analysis step of obtaining a luminance abnormality point range where the luminance abnormality points are close to each other, and scoring a distribution of luminance abnormality points based on the luminance abnormality point range and the luminance of the luminance abnormality point. The luminance unevenness is analyzed based on the score obtained in the luminance abnormality point analyzing step (S2 in FIG. 9).

  This test sample is a sample to be scored for luminance unevenness. Specifically, it is a sample that is the same type as the standard sample, and that requires pass / fail judgment like an actual product. For such a test sample, the luminance image is first analyzed by the luminance image analysis step as in the case of the standard sample (S21 in FIG. 9). Then, the luminance image of the test sample is compared with the threshold value determined in the standard luminance distribution analysis step, and a pixel at a point that deviates from the threshold value is specified as a luminance abnormality point (S22 in FIG. 9).

  After specifying the abnormal luminance point, an abnormal luminance point range is obtained for a point closer to the abnormal luminance point. Then, the distribution of the abnormal luminance point is scored using a combination parameter of the range of the abnormal luminance point range and the luminance of the abnormal luminance point (S23 in FIG. 9).

  What is called unevenness is hardly recognized when a human observes even if visually abnormal parts (abnormal points) exist as discrete points. On the other hand, when anomalous points gather and occupy a certain range (when it is a lump that is close to many), it is easy to recognize that range as unevenness. In order to perform scoring reflecting the influence of the range (lumps) of abnormal points, a luminance abnormal point range specified as a range in which the above-described abnormal points are close to each other is obtained. The proximity width here is appropriately set according to the sample of the object to be inspected. For example, the adjacent range may be specified as the same range only when the adjacent pixel is an abnormal point, or the distance as the pixel is 2 If there is an abnormal point within a point, it may be set so that it is within the same range as a continuous range.

  In this way, after specifying an abnormal point as an abnormal point range including not only a single point but also within a close range, the frequency is set using a combination parameter of the range and the luminance. . This combination parameter is a parameter for analyzing the combination of the value of the range and the brightness. That is, it is processed into a parameter as an index that reflects the influence of both the value, the degree, etc. of the sum, product, and ratio thereof. As a simple example, “the width of the same abnormal point range” × “the average luminance within the same abnormal point range” is set as the predetermined abnormal point or the abnormal point frequency of the abnormal point range. Then, by evaluating how much this abnormal point frequency exists in the entire sample, the luminance distribution is scored (S23 in FIG. 9). This score is displayed on the display unit or the like (S3 in FIG. 9). These analyzes can be carried out by a computer or the like as a program for executing the steps as shown in FIG. 9, and information necessary for analysis such as the program itself, captured images, threshold values based on standard samples, etc. The program is appropriately stored in a memory and executed.

  If such an analysis is performed, it is possible to evaluate a test sample based only on the standard sample. When the test sample has no unevenness, there are few abnormal points and it does not exist as a lump, so the score of the luminance distribution described above is a score with small unevenness. On the other hand, if there is unevenness, the influence of the lump is also evaluated at the same time according to the degree to which the abnormal point exists as a lump, so the brightness distribution score becomes uneven as the lump is easily recognized as unevenness. A big score. This is a technique that does not require so-called teaching that accumulates a plurality of conventional sample materials and test sample information, and is unlikely to cause a deviation due to them.

(Seventh embodiment of the present invention)
This unevenness evaluation method can also be performed on an image captured as a polarization component. In accordance with the sixth embodiment described above, instead of the luminance in the sixth embodiment, the analysis based on the polarization component may be performed as a nonuniformity due to the polarization component by performing the flow as shown in FIG. . For this purpose, using a surface inspection apparatus as disclosed in the second embodiment, in addition to the sixth embodiment, light scattered in the opening direction from the object to be inspected passes through the beam splitter. A surface inspection method including a step of polarization separation by a polarization filter provided in a direction and provided between the beam splitter and the imaging unit. Then, since the polarized light is separated in this polarization separation process, an image of the polarized component is obtained in the imaging unit. For further detailed analysis of polarization components, it is also effective to obtain polarization component images at a plurality of (preferably 3 or more) angles by polarization filter rotating means and obtain information on polarization components based thereon. .

  Further, the unevenness score due to the luminance and the unevenness score due to the polarization component may be displayed together, and the degree of unevenness due to the luminance for the same pixel and the extent of unevenness due to the polarization component may be compared to each other. It can also be displayed as a graph set on the axis and the Y axis.

(Eighth embodiment of the present invention)
The unevenness evaluation methods of the sixth and seventh embodiments described above can also be performed on images that have been picked up by a method other than the image picked up by the first embodiment or the like.

For example, by using the analysis method of the sixth embodiment described above, the inspection range of the object to be inspected is specified from the image captured by the imaging means capable of capturing an image for each predetermined pixel, and the inspection target A luminance image analysis step for obtaining a luminance for each pixel in the range, wherein the luminance image analysis step determines a threshold value based on the luminance distribution of the standard sample, and the luminance image analysis step Obtain the luminance for each pixel, obtain the luminance abnormal point of the test sample by comparing with the threshold obtained by the standard luminance distribution analysis step, obtain the luminance abnormal point range where the luminance abnormal points are close to each other, and A luminance abnormality point analysis step of scoring the distribution of luminance abnormality points based on a combination parameter of the point range and the luminance of the luminance abnormality point, and based on the score obtained by the luminance abnormality point analysis step. There are, analyzing the luminance unevenness can be the invention of a surface inspection method (eighth embodiment A).
Furthermore, this luminance may be implemented as a luminance specifying a color, and color unevenness analysis can be performed by analyzing luminance unevenness of a specific color. Moreover, it can also be set as the apparatus which has a means corresponding to each process, and the program for performing this.

  Further, in the eighth embodiment described above, by using the analysis method of the seventh embodiment described above, an image for each predetermined pixel can be captured as an image of a polarization component, and the image is captured by the imaging process. A polarization component image analysis step of specifying an inspection range of the object to be inspected from an image and obtaining a polarization component for each pixel of the inspection range, and based on a polarization component distribution of a standard sample by the polarization component image analysis step A standard polarization component distribution analysis step for determining a threshold value and a polarization component image analysis step for obtaining a polarization component for each pixel of the test sample, and comparing with the threshold value obtained by the standard polarization component distribution analysis step for the test sample. A polarization component abnormal point is obtained, a polarization component abnormal point range where the polarization component abnormal points are close to each other is obtained, and a polarization component is determined from a combination parameter of the polarization component abnormal point range and the polarization component of the polarization component abnormal point. And a polarization component abnormal point analysis step for scoring the distribution of abnormal points, and analyzing the polarization component unevenness based on the score obtained by the polarization component abnormal point analysis step. (Eighth embodiment B). Moreover, it can also be set as the apparatus which has a means corresponding to each process, and the program for performing this. And these brightness | luminance nonuniformity and polarization component nonuniformity can also be set as the inspection method which combined each score.

  In the eighth embodiment, the unevenness score due to luminance and the unevenness score due to the polarization component may be displayed and evaluated together. For example, by comparing the degree of unevenness due to luminance with respect to the same pixel and the degree of unevenness due to the polarization component and displaying them as graphs set on the X axis and the Y axis, respectively, luminance (color) unevenness and polarization component unevenness Can be used as an indicator that can be visually grasped comprehensively.

  In this eighth embodiment, the imaging of each predetermined pixel for luminance (color) unevenness analysis and the imaging of each predetermined pixel for polarization component unevenness analysis are, for example, the present invention. The technique disclosed in Japanese Patent Laid-Open No. 2006-138790, which is the inventor, can be used. Therefore, in the detailed description according to the present application, the disclosure according to JP-A-2006-138790 is cited. JP-A-2006-138790 discloses a surface inspection apparatus that analyzes the scattered light of irradiated light and inspects the properties of the object surface irradiated with the light. Polarization component separating means for separating the P polarization component, which is a vibration component, and S polarization component, which is a vibration component perpendicular to the scattering surface, and the P polarization component and the S polarization separated by the polarization component separation means A polarization component image detecting means for detecting each of the components as a polarization component image, "and" a color component image detecting means for detecting the scattered light as a plurality of detection images relating to the intensity of light of a plurality of wavelengths. " (Claim 1 etc.). The analysis is performed by a predetermined means (process). In the present invention, a detection image by the color component image detection means can be used for analysis of luminance unevenness. In addition, the polarization component image obtained by the image detection means can be used for analyzing the polarization component unevenness. Alternatively, a polarization intensity ratio correlation parameter or a color intensity ratio correlation parameter relating to these images may be used.

  For example, a case will be described in which a gold-plated pad as shown in FIG. 12 is evaluated by a surface inspection apparatus as shown in FIG. 11 configured according to the technique of JP-A-2006-138790. A camera 1 that obtains an image that has passed through the S polarizing plate in FIG. 11 and a camera 2 that obtains an image that has passed through the P polarizing plate (P′-polarized image) via a beam splitter and a mirror are provided. Note that all of these cameras can obtain RGB images, and assume that 150 × 150 pixels are to be analyzed and displayed from the captured image. Then, in the P′-polarized image and the S′-polarized image, the values of RP ′ + RS ′ and GP ′ + GS ′ are obtained from the RGB luminance components of each camera as an image corresponding to the color component image detecting means, and a combination of both The color distribution was examined from the parameter size. As the polarization intensity ratio correlation parameter, parameter Ψ = tan−1 (intensity of S-polarized component / intensity of P-polarized component) was used. Since this parameter Ψ has a correlation with gloss, it can be used as an index of uneven gloss.

  An example in which an image acquired by the optical system having such a configuration is analyzed by combining the eighth embodiment A and the eighth embodiment B will be described. This example shows an evaluation example of a non-defective product (FIG. 12A) and a defective product (FIG. 12B) of a gold plating pad as shown in FIG. Note that the threshold value set by the standard sample for performing this analysis is set using an ideal sample that is even less uneven than the non-defective product. In addition, this threshold was set so that “average value ± 6σ” in the standard sample was a non-abnormal point. 12A and 12B, the left side of each lower stage is a combination parameter related to gloss unevenness (based on polarization components) for each pixel on the horizontal axis, and a combination parameter related to color unevenness (based on luminance unevenness) on the vertical axis. Is displayed. In addition, since there are many identical plots in this two-dimensional coordinate (particularly non-abnormal points), the frequency is shown on the lower right side.

  As shown in FIG. 12, in the non-defective product, since there are few non-abnormal points, the combination parameters of the gloss unevenness and the color unevenness are concentrated at the reference point near the center. Then, with the gloss unevenness and color unevenness of each pixel of the non-defective product and the distance from the origin by plotting as an index, the sum of the distances was scored, and the point of the unevenness score was one point. On the other hand, when scored in the same manner for defective products, both gloss unevenness and color unevenness spread greatly, and the number of uneven points according to the above standard was 550 points. In this defective product, unevenness characteristics appear in the direction of about 45 ° on the two-dimensional plane of color unevenness and gloss unevenness, and it was also confirmed that the color unevenness tendency and the gloss unevenness tendency generally correspond to this defective product. .

[Surface inspection device A]
The following experiment was performed using a surface inspection apparatus according to the fourth embodiment. In this experiment, the main configuration is as follows.
Diffusion part: A cylinder having a diameter of 15 mm and a height of 50 mm produced using white cardboard was used as the diffusion part. Note that a black lasha paper was placed on the bottom of the cylinder (opposite the opening), and light scattering was less likely to occur from around the object to be inspected during imaging.
First light source: LED lighting device “LFV40SW” (CCS)
Beam splitter: “TS plate type B / S VIS 50R / 50T 50 X 50” (Edmond Optics)
Diffuser: “Opal Light Diffusing Glass 125 X 125” (Edmond Optics)
Imaging unit: CCD camera “DFK31AU03” (Argo)
Polarizing filter: Polarizing plate “USP-50C-38” (Sigma Kogyo Co., Ltd.)
Inspected object: φ6mm, metal sphere

[Example 1]
FIG. 13 (right side) shows the result of imaging the object to be inspected with the polarization filter of the surface inspection apparatus A removed.
[Comparative Example 1]
FIG. 13 (left side) shows the result of imaging the inspected object with the diffuser plate and the reflecting mirror (second illumination unit) removed from Example 1.

When the images of Example 1 and Comparative Example 1 in FIG. 13 are observed, a round dark spot portion is seen in the vicinity of the center of the photographed image of the inspected object in Comparative Example 1 on the left side. In Comparative Example 1, since there is no diffusion plate and no second illumination part, it is considered that there is almost no light irradiated from the opening part side of the diffusion part 1, and it becomes a blind spot and becomes a dark spot part. .
On the other hand, in the imaging result of Example 1 on the right side, there is no dark spot portion as seen in Comparative Example 1, and an image in which the upper half of the inspected object that is a sphere is uniformly irradiated can be obtained. Yes. Since such a uniform image can be acquired, it is clear that the place where the irradiation intensity of the object to be inspected is reduced, and it is easy to inspect scratches and dents.

[Example 2]
FIG. 14 shows the result of imaging the object to be inspected using the surface inspection apparatus A. Here, the polarization filter was rotated to detect linearly polarized light components in three directions of 0 degree, 45 degrees, and 90 degrees. An image obtained by detecting each polarization component is an image shown in FIG.

  Furthermore, based on the intensity | strength of the polarization component shown in FIG. 14, the main axis | shaft of the ellipse as elliptically polarized light for every pixel, and the ellipticity were calculated | required. This ellipticity distribution is shown in FIG. As shown in FIG. 15, an abnormal point corresponding to a clear defect is displayed as a white point due to a difference in ellipticity, but in addition to this, a pattern with relatively low contrast and a black point can be observed. By confirming these points, and comparing and examining them, it is possible to discriminate and detect defects and the like and perform surface inspection with better separation than mere observation of free-form surfaces.

  INDUSTRIAL APPLICABILITY According to the present invention, a surface of a sphere that has a free curved surface can be uniformly irradiated with light, and various applications can be made as an inspection technique such as a surface inspection of a metal sphere, which is industrially useful. .

DESCRIPTION OF SYMBOLS 1, 11, 12 Diffusion part 101,102,103,104 Surface inspection apparatus 2 1st light source 3,31 Beam splitter 4 Diffusion plate 41 2nd light source 42 Reflector 5 Imaging part 51 Objective lens 6 Polarizing filter 7 Inspected Body 71 Ball to be inspected 81 Image detection means 82, 821 Image analysis means 83 Display unit

Claims (14)

A hollow diffusion part having an opening that can contain the object to be inspected;
A first illumination unit that emits light from outside the diffusion unit toward the diffusion unit;
A beam splitter provided at an angle inclined with respect to the optical axis of light scattered from the object to be inspected in the opening direction of the opening;
A diffusion plate provided in a direction in which light scattered from the object to be inspected and incident on a beam splitter is reflected by the beam splitter;
A surface inspection apparatus comprising: an imaging unit that detects light scattered from the object to be inspected in the opening direction and transmitted through the beam splitter.   2. The apparatus according to claim 1, further comprising a polarizing filter provided in a direction in which light scattered from the object to be inspected in the opening direction passes through the beam splitter and provided between the beam splitter and the imaging unit. Surface inspection device.   The surface inspection apparatus according to claim 1, further comprising a second illumination unit configured to irradiate the diffusion plate with light in the direction of the beam splitter.   The surface inspection apparatus according to claim 1, wherein the diffusion unit is a diffusion unit having a pattern portion of a predetermined color.   The surface inspection apparatus according to claim 1, wherein the imaging unit is an imaging unit that captures images as a plurality of detection images relating to light intensities having a plurality of wavelengths.   The surface inspection apparatus according to claim 2, further comprising a polarization filter rotation unit configured to rotate the polarization filter and capture a polarization component image having at least three angles.   The surface inspection apparatus according to claim 1, wherein the object to be inspected has a free-form surface. A step of placing the object to be inspected inside a hollow diffusion part that can contain the object to be inspected and has an opening;
Irradiating the diffusing portion from the outside by a first illumination unit irradiating light toward the diffusing portion from outside the diffusing portion; and
Separating the light incident on the beam splitter by a beam splitter provided at an angle inclined with respect to the optical axis of the light scattered in the opening direction of the opening from the inspection object;
The light incident on the diffusion plate is reflected by the diffusion plate provided in a direction in which the light scattered from the object to be inspected in the opening direction and reflected on the beam splitter is reflected. Irradiating the object to be inspected from the opening side;
A surface inspection method including a step of imaging by an imaging unit that detects light scattered from the object to be inspected in the opening direction and transmitted through the beam splitter and captures the light as an image. The surface inspection method according to claim 8,
An image for each predetermined pixel can be picked up in the step of picking up images, the inspection range of the object to be inspected is specified from the image picked up in the step of picking up the image, and the luminance for each pixel in the inspection range is obtained A luminance image analysis step,
In the luminance image analysis step, a luminance for each pixel of a standard sample as the object to be inspected, a standard luminance distribution analysis step for obtaining a threshold value based on a luminance distribution for each pixel of the standard sample,
The luminance image analysis step determines the luminance for each pixel of the test sample as the object to be inspected, and the luminance abnormality for specifying the luminance abnormality point of the test sample by comparing with the threshold value obtained by the standard luminance distribution analysis step A point identification process;
The abnormal luminance point range in which the abnormal luminance points specified by the abnormal luminance point specifying step are close to each other is obtained, and the abnormal luminance point of the test sample is determined by a combination parameter of the abnormal luminance point range and the luminance of the abnormal luminance point. A luminance abnormality point analysis step for scoring the distribution,
A surface inspection method for analyzing luminance unevenness based on a score in the luminance abnormality point analyzing step.   And a step of separating the polarized light by a polarizing filter provided between the beam splitter and the imaging unit, provided in a direction in which light scattered in the opening direction from the object to be inspected passes through the beam splitter. The surface inspection method according to claim 8. The surface inspection method according to claim 10.
An image for each predetermined pixel can be captured in the imaging step, the inspection range of the inspection object is specified from the image captured in the imaging step, and a polarization component for each pixel in the inspection range is determined. A polarization component image analysis step to be obtained,
By the polarization component image analysis step, a polarization component distribution analysis step for obtaining a polarization component for each pixel of the standard sample as the object to be inspected, and obtaining a threshold value based on a polarization component distribution for each pixel of the standard sample;
By the polarization component image analysis step, a polarization component for each pixel of the test sample is obtained as the object to be inspected, and the polarization component abnormality point of the test sample is compared with the threshold value obtained by the standard polarization component distribution analysis step. A polarization component abnormal point identifying step to identify;
A polarization component abnormal point range in which the polarization component abnormal points specified by the polarization component abnormal point specifying step are close to each other is obtained, and the test is performed based on a combination parameter of the polarization component abnormal point range and the polarization component of the polarization component abnormal point. A polarization component abnormal point analysis step for scoring the distribution of polarization component abnormal points of the sample,
A surface inspection method for analyzing polarization component unevenness based on a score in the polarization component abnormal point analysis step. A first illuminating unit that can contain the object to be inspected and arranges the object to be inspected inside a hollow diffusion part having an opening, and irradiates light toward the diffusion part from the outside of the diffusion part By irradiating the diffusion part from the outside, the light incident on the beam splitter is separated by a beam splitter provided at an angle inclined with respect to the optical axis of the light scattered from the object to be inspected in the opening direction of the opening. The light incident on the diffusion plate is reflected on the beam splitter by the diffusion plate provided in the direction in which the light that is scattered from the object to be inspected and is incident on the beam splitter is reflected through the beam splitter. The object to be inspected is irradiated from the opening side, and is picked up by an image pickup unit that detects the light scattered from the object to be inspected in the opening direction and transmitted through the beam splitter and picks up an image. By using the image,
A luminance image analysis means for specifying an inspection range of the object to be inspected from the captured image and obtaining a luminance for each pixel of the inspection range;
The luminance image analysis means obtains the luminance for each pixel of the standard sample as the object to be inspected, and the standard luminance distribution analysis means obtains a threshold value based on the luminance distribution for each pixel of the standard sample,
The luminance image analysis means determines the luminance of each pixel of the test sample as the object to be inspected, and compares the threshold obtained by the standard luminance distribution analysis means with the luminance abnormality point of the test sample. Point identification means;
A luminance abnormal point range in which the abnormal luminance points specified by the abnormal luminance point specifying means are close to each other is obtained, and a luminance abnormal point range of the test sample is determined by a combination parameter of the abnormal luminance point range and the luminance of the abnormal luminance point. A surface inspection program for causing a computer to execute luminance abnormality point analysis means for scoring the distribution. A first illuminating unit that can contain the object to be inspected and arranges the object to be inspected inside a hollow diffusion part having an opening, and irradiates light toward the diffusion part from the outside of the diffusion part By irradiating the diffusion part from the outside, the light incident on the beam splitter is separated by a beam splitter provided at an angle inclined with respect to the optical axis of the light scattered from the object to be inspected in the opening direction of the opening. The light incident on the diffusion plate is reflected on the beam splitter by the diffusion plate provided in the direction in which the light that is scattered from the object to be inspected and is incident on the beam splitter is reflected through the beam splitter. Irradiating the object to be inspected from the opening side, light scattered from the object to be inspected in the opening direction, transmitted through the beam splitter, and scattered from the object to be inspected in the opening direction Serial provided in a direction that passes through the beam splitter, by using an image captured by the imaging unit that captures the detected image light which has polarization separation by the polarization filter provided between the beam splitter and the imaging unit,
A polarization component image analyzing means for specifying a test range of the test object from the captured image and obtaining a polarization component for each pixel of the test range;
The polarization component image analysis means obtains a polarization component for each pixel of the standard sample as the object to be inspected, and a standard polarization component distribution analysis means for obtaining a threshold value based on the distribution of the polarization component for each pixel of the standard sample;
The polarization component image analysis means obtains the polarization component for each pixel of the test sample as the object to be inspected, and compares the polarization component abnormality point of the test sample with the threshold value obtained by the standard polarization component distribution analysis means. Means for identifying the polarization component abnormal point to be identified;
A polarization component abnormal point range in which the polarization component abnormal points specified by the polarization component abnormal point specifying unit are close to each other is obtained, and the test is performed according to a combination parameter of the polarization component abnormal point range and the polarization component of the polarization component abnormal point. A surface inspection program for causing a computer to execute polarization component abnormal point analysis means for scoring the distribution of polarization component abnormal points of a sample.   The computer-readable recording medium which recorded the surface inspection program of Claim 12 or 13.