JP2821460B2 - Inspection device for transparent substrate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flaw inspection apparatus for a transparent substrate having improved flaw inspection precision, and more particularly to a flaw inspection apparatus suitable for inspecting flaws present on a quartz blank.

[0002]

2. Description of the Related Art Although a quartz resonator is formed from a quartz blank, even if there is a slight flaw in the quartz blank, the quartz resonator becomes defective, and therefore, detection of a scratch on the quartz blank is very important.

Hitherto, humans have inspected the quartz blank for scratches visually. This is to work under a fluorescent lamp without irradiating any special light, and relying on visual observation, it has been extremely difficult to detect a flaw (defect) of several tens μm or less. In addition, since the work is continuously performed for a long time, fatigue is also severe, and as a result, a stable inspection result cannot be obtained. . For this reason, there has been a demand for a flaw inspection device by image processing without manual intervention.

As a conventional flaw inspection apparatus using such image processing, there is, for example, an invention described in Japanese Patent Application Laid-Open No. Hei 7-103905 (hereinafter simply referred to as a gazette) and its prior art.

[0005] (1) In the prior art described in the official gazette (hereinafter, referred to as an oblique irradiation method), as shown in FIG. The surface of the inspection object 1 is irradiated with light from an oblique direction by using the oblique illumination 8 in order to irradiate and prevent shadows and more reliably detect cracks. CCD camera 3 provided with light reflected from the surface of the object 1 just above the object 1
, An image of the inspection object 1 is taken into the image input unit 5, and further processed through the feature extraction unit 6 and the determination unit 7.

(2) The invention described in the official gazette (hereinafter, referred to as a switching system) is, as shown in FIG.
Lights 12 to 14 are arranged at different positions to irradiate the inspection object 1 with light from three directions.
The cameras 10 to 11 are arranged. These CCD cameras 1
0 to 11 and illuminations 12 to 14 are arranged at positions at an angle of 45 ° with respect to the horizontal plane of the inspection object 1. Thus, three illuminations 12 to 14 and two CCD cameras 10 to 1
1, only one camera and one illumination are turned on at the same time, and the others are turned off. This combination of on and off is 4
Then, four images are captured by the cameras 10 to 11 and cover a detection range of 360 °. Each image is stored in the image input unit 15, and the determination is performed for each of these image signals through the feature extraction unit 16 and the pass / fail determination unit 17 to detect a defect such as a scratch independent of the crack direction.

[0007]

However, the above-mentioned prior art has the following problems.

(1) The oblique irradiation method has the following disadvantages.

Although the use of oblique illumination makes it easier to detect cracks, the shadowless illumination having a ring-shaped light-emitting portion irradiates light from directly above the inspected object so that no shadow is formed on the image. Therefore, in addition to the scratches, the entire image of the object to be inspected is also superimposed on the camera. Therefore, it is difficult to clearly extract only the image of the flaw from the whole image unless the flaw is properly emphasized by oblique illumination, and the detection sensitivity is low.

[0010] Further, since only one oblique illumination is used, the irradiation direction is limited, and depending on the direction of the flaw, a blind spot occurs, and the flaw detection performance is reduced.

(2) The switching system has the following disadvantages.

Since irradiation and imaging are performed from a diagonal direction using a plurality of illuminations and cameras, focusing and setting of light conditions cannot be set to the same level for all images, and accurate detection cannot be performed. .

Since the camera is installed in an oblique direction, the image becomes elliptical and accurate dimensions and measurement cannot be made. In order to accurately measure and measure dimensions, complicated correction processing is required.

[0014] Since the camera and the illumination are switched, the control is complicated. In addition, a large number of images are required to inspect one inspection object, the detection algorithm is complicated, and the image processing speed cannot be increased.

[0015] Both the camera and the lighting are 4
Since it is arranged at a position having an angle of 5 °, there is a possibility that an image of the surface of the mounting table on which the object to be inspected is placed may be input, so that the S / N ratio for the image of the scratch or defect becomes worse, and detection is difficult. Could be

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to optically emphasize the flaws on the transparent substrate, so that the flaws on the transparent substrate can be easily, reliably and quickly recognized. An object of the present invention is to provide a flaw inspection device.

[0017]

According to the first aspect of the present invention, a transparent substrate irradiated with light is imaged by an image pickup means, and a characteristic of a flaw present on the transparent substrate is extracted from an image signal of the imaged image. In a transparent substrate flaw inspection apparatus that determines the presence of a flaw based on the extracted signal,
An illuminating means for irradiating light from the entire circumference of the side surface of the transparent substrate at an irradiation angle within a range of 30 °, and a diffusing plate for irradiating the transparent substrate with light by diffusing light emitted from the illuminating means to the transparent substrate. Imaging means arranged at a position where the imaging direction is perpendicular to the substrate surface of the transparent substrate.

As in the present invention, when light is irradiated at an irradiation angle within a range of ± 30 ° from the side surface of the transparent substrate to the substrate surface of the transparent substrate, the imaging direction is changed with respect to the substrate surface of the transparent substrate. Since the imaging means is arranged at a vertical position, light that simply passes through the transparent substrate or is reflected on the substrate surface does not reach the imaging means, so that the entire image of the transparent substrate is not captured. The light reaching the imaging means is only a scratch existing on the transparent substrate or reflected light reflected by the side surface (edge) of the transparent substrate. Light is irradiated from all directions around the transparent substrate, and the light is scattered by the diffuser, so the reflected light reflected at the scratches or edges is emphasized, and only the scratches or edges are clearly displayed on the image. Emerge. By processing this image, flaws can be easily inspected.

According to a second aspect of the present invention, a transparent substrate irradiated with light is imaged by an image pickup means, a feature of a flaw present on the transparent substrate is extracted from an image signal of the imaged, and a signal is generated based on the extracted signal. In a transparent substrate flaw inspection device that determines the presence of a flaw, a transparent mounting substrate that horizontally mounts the transparent substrate, diffuses light emitted from below the transparent substrate, and irradiates the transparent substrate with scattered light. And irradiating light at an irradiation angle within a range of 0 ° to −30 ° with respect to the substrate surface of the transparent substrate from the entire circumferential direction of the side surface of the transparent substrate mounted on the diffusion mounting table provided below the diffusion mounting table. Ring-shaped illuminating means, and imaging means arranged at a position directly above the image-capturing direction perpendicular to the substrate surface of the transparent substrate mounted on the diffusion mounting table.

Light emitted from the ring-shaped illuminating means is scattered when passing through the diffusion mounting table, and the scattered light is transparent to the substrate surface of the transparent substrate at an irradiation angle within a range of 0 ° to -30 °. The substrate is irradiated. Then, similarly to the first aspect, only the scratches or edges clearly appear on the image.

According to a third aspect of the present invention, a transparent substrate irradiated with light is imaged by an image pickup means, a feature of a flaw present on the transparent substrate is extracted from a captured image signal, and a flaw is detected based on the extracted signal. In a transparent substrate flaw inspection device that determines the presence of a transparent substrate, a mounting table that horizontally mounts the transparent substrate, and a transparent substrate that is provided above the mounting table and that extends from all sides of the transparent substrate mounted on the mounting table. Ring-shaped illuminating means for irradiating light at an irradiation angle within the range of 0 ° to + 30 ° with respect to the substrate surface, and diffusing light emitted from the ring-shaped illuminating means to the transparent substrate to scatter light. , And an imaging means arranged at a position directly above the imaging direction perpendicular to the substrate surface of the transparent substrate placed on the mounting table.

The light emitted from the ring-shaped illumination means is diffused when passing through the diffusion plate, and the scattered light strikes the transparent substrate at an irradiation angle within the range of 0 ° to + 30 ° with respect to the substrate surface of the transparent substrate. Irradiate. Then, similarly to the invention described in claim 1,
Only the scratches or edges clearly appear on the image.

According to a fourth aspect of the present invention, a transparent substrate irradiated with light is imaged by an image pickup means, and the characteristics of a flaw present on the transparent substrate are extracted from an image signal obtained by the imaging, and a flaw is detected based on the extracted signal. In the transparent substrate flaw inspection apparatus for determining the presence of the opaque mounting table for horizontally mounting the transparent substrate, and placed on the mounting table to surround the transparent substrate mounted on the mounting table, light is A transparent ring that transmits light, an opaque ring placed on the transparent ring to block light, a ring-shaped illuminating unit that is arranged around the transparent ring and irradiates light to the transparent substrate via the transparent ring, and an illuminating unit A diffuser plate that scatters light illuminating the transparent substrate by diffusing the light illuminating the transparent substrate from above, and is located at a position directly above the imaging direction perpendicular to the substrate surface of the transparent substrate placed on the mounting table Opaque mounting table and Light incident on the ring from the ring-shaped illuminating means via the transparent ring interposed between the transparent substrate and the transparent substrate is within a range of 0 ° to + 30 ° with respect to the transparent substrate from the entire circumferential direction of the side surface of the transparent substrate. The thickness of the transparent ring is set so that irradiation is performed at an irradiation angle of.

Light emitted from the ring-shaped illuminating means is regulated by the opaque ring and the opaque mounting table, passes only through the transparent ring provided therebetween, and extends in the entire circumferential direction of the side surface of the transparent substrate housed inside the transparent ring. Irradiation is performed at an irradiation angle within a range of 0 ° to + 30 °. Therefore, only the flaws or edges clearly appear on the image. In this case, since the transparent ring is sandwiched between the opaque ring and the opaque mounting table to regulate the optical path incident on the inside of the ring, it is not necessary to attach a component or the like for regulating the irradiation angle to the illumination means side.

According to a fifth aspect of the present invention, there is provided the transparent substrate flaw inspection apparatus according to any one of the first to fourth aspects, wherein the transparent substrate is a crystal blank for a crystal unit. In the case where the transparent substrate is a quartz blank for a quartz oscillator having a small area and a small thickness, flaws can be effectively inspected.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a transparent substrate flaw inspection apparatus of the present invention is applied to a crystal blank for a crystal unit will be described below with reference to the drawings. FIG. 1 is a principle diagram, FIGS.
FIG.

In FIG. 1, reference numeral 21 denotes a strip-shaped crystal blank, which has a long side of usually 3 mm to 50 mm and a thickness of 3 mm.
The size is about 0 μm to 500 μm. The shape of the crystal blank is not limited to a rectangular shape, but may be a circle or any other shape. A ring light 22 is horizontally arranged as an illuminating means around the crystal blank 21 so as to surround the crystal blank 21 with the front and rear surfaces arranged vertically with the front and back facing up and down. Light is applied to the back surface (substrate surface) at an irradiation angle within a range of ± 30 °. Here, the ± signs attached to the irradiation angles indicate + on the front side of the quartz blank 21 and − on the back side. In order to set the irradiation angle within the range of ± 30 °, a part of the ring light 22 that does not want to contribute to irradiation is covered with a light shielding plate or a light shielding film.

Generally, the simplest and cheapest fluorescent lamp can be used as the ring light 22, but it is not limited to this. For example, a ring-shaped outlet may be provided radially inward, and the ring-shaped outlet may be connected to a light source via an optical fiber, and light emitted from the light source may be emitted from the ring-shaped outlet through the optical fiber. Alternatively, the light from the light source may be reflected on the mirror using a ring-shaped mirror, and the crystal blank 21 may be illuminated from the entire circumferential direction.

When a fluorescent lamp is used as the ring light 22, the light emitted from the fluorescent lamp is not necessarily required because it is already scattered light. A ring-shaped diffusing plate 23 is arranged between the ring lights 22 and the quartz blank 2.
1 scatters the irradiating light and diffuses the scattered light into a quartz blank 2.
1 may be irradiated. The reason why the light from the ring light 22 is diffused into scattered light is to irradiate the quartz blank 21 with light from all directions within an irradiation angle range of ± 30 °. The simplest and cheapest frosted glass can be used as the diffusion plate 23.

The imaging means 26 is arranged at a position directly above the surface of the crystal blank 21 in a direction perpendicular to the imaging direction. As the imaging means 26, for example, a CCD camera 25 and a microscope 24 can be used, and the imaging means 26 is set so that only the vicinity of the crystal blank is included in the field of view. Note that the imaging means 26 is a quartz blank 2
The crystal blank 21 may be disposed at a position immediately below the back surface of the first device 1 or in a case where the crystal blank 21 is disposed vertically.

The image pickup means 26 and the ring light 22 are controlled by the image input means 26, respectively, and the image signals picked up by the image pickup means 26 are passed through the image input means 27 and the feature extraction means 28, and are judged by the judgment means 29.
Is input to Since the imaging means 26 only fits in the field of view near the quartz blank, it is possible to detect the change in the brightness of the field of view at high speed by image processing.

As described above, when scattered light is irradiated from the ring light 22 surrounding the crystal blank 21 to the crystal blank 21, when viewed from above, as shown in FIG. Will be wrapped around the entire side. Figure 2 when viewed from the side
As shown in (b), the scattered light 20 in the horizontal and oblique directions covers the entire side surface at the irradiation angle. In this case, light should not be irradiated from directly above or directly below. When illuminated from directly above or below, an image of the quartz blank 21 is transmitted or reflected by the CCD camera 2.
This is because it is reflected in 5. In addition, the crystal blank 21
This is because, when there is a mounting table that supports, the underlying pattern is clearly seen, and it is difficult to determine a scratch (defect) existing in the crystal blank 21.

When the crystal blank 21 is irradiated with light, the reflected light energy at the scratched or defective portion of the crystal blank 21 or the edge processed portion increases. This is because, as shown in FIG. 3A, the direction of light emitted from the periphery of the quartz blank 21 is omnidirectional in the horizontal direction due to scattering. If there is no defect in the quartz blank 21, the optical path is not blocked, and the scattered light 20 passes as it is as transmitted light. On the other hand, if the flaw 31 is present, the light hits the flaw 31 and becomes reflected light to be emphasized.

That is, as shown in FIG. 3B viewed from the side, when the scattered light 20 hits the flaw 31, it is reflected and a flaw appears on the surface of the quartz blank 21. Fig. 3
As shown in (c), the light 20 is radiated to the scratch 31 from all directions, so that the energy of the reflected light of the scratch 31 is emphasized.
Looks sharp. Since a crystal defect has all directions, when irradiated with light in one direction, scratches parallel to the light do not reflect and are difficult to detect, and when irradiated with light in three directions. However, it was difficult to accurately detect a flaw because the SN ratio was poor. However, as in the present invention, the S / N ratio can be remarkably improved by intensively irradiating light from all directions and all directions to the flaw 31 and using the synergistic effect of light to detect a small flaw accurately. It became possible. In particular, it is possible to detect even a flaw (10 μm or less) that is difficult to detect with human eyes by relatively increasing the light amount.

Further, since an image can be taken and image-processed with the entire crystal blank as a field of view at a time, even a small flaw (10 μm or less) can be detected at high speed. For example, even when the image is processed as a 512 × 512 image, it can be detected at a speed of 200 mS or less.
The same is true for any number of scratches in a single crystal blank.

Further, even a small flaw of 10 μm or less has a large light energy and can be stably detected, so that it is easy to automate the image processing.

As a secondary effect, if the edge processing accuracy of the peripheral surface of the crystal blank is rough, the reflection of light at the edge portion increases, but if the accuracy is good, the reflection decreases. It can be applied to inspection of processing accuracy. Also, if you use the reflection on the edge processing surface,
It can also be applied to shape and size measurements of quartz blanks.

It should be noted that even if there is a flaw parallel to the axial direction of the camera 25, the flaw can be easily detected for the following reason. Usually several tens to 50 quartz blanks
It is extremely thin at 0 μm. The scratches on the crystal blank are caused by external stress, and there are always traces of the scratches. Therefore, if there is a flaw, the flaw is always in contact with the surface and cannot exist only inside the flaw. If the surface of the wound is irradiated with light from the surroundings, the light is complicatedly refracted and reflected at the cut, so that even though the camera 25 is arranged directly above, high light energy is generated in that part, Such wounds can be seen.

Here, the grounds for setting the light irradiation angle on the surface of the quartz blank within the range of ± 30 ° will be described with reference to FIGS. As shown in FIG. 4, light is applied to one point (edge) of the long side of the strip-shaped quartz blank 21 placed on an opaque plastic placing table, and the light energy of the reflection at that point is measured. This light energy has a strong correlation with the light energy at the flaw, and the higher the light energy, the easier the flaw detection. As shown in FIG. 5, light irradiation is performed by using an optical fiber light source 18 having a condensing lens at an emission end at a position 100 mm away from the quartz blank, and increasing the irradiation angle to the surface of the horizontally arranged quartz blank by + 5 °. , +10
° ... + 40 °, + 45 °, etc., in increments of 5 °. Then, as shown in FIG.
Up to °, the SN ratio is large and the scratch 31 can be clearly distinguished,
If it exceeds that, it becomes clear that the underlying pattern of the mounting table appears more often, making it difficult to determine. At 45 °, the image of the scratch 31 is completely absorbed by the underlying pattern, and it is found that the scratch 31 cannot be detected. From FIG. 7 plotting light energy,
The irradiation angle of light on the surface of the crystal blank is ± 30 °
, Preferably within the range of ± 20 °, and within the range of ± 5 ° if a practically optimum numerical value is shown. Note that the vertical axis in FIG. 7 indicates the magnitude of light energy with the maximum being 255.

Next, a description will be given of a specific embodiment of the flaw inspection apparatus in which the image pickup means is disposed right above the crystal blank.

FIG. 8 shows a first embodiment in which a transparent glass plate is used as a mounting table on which a quartz blank is mounted, and a ring light is arranged below the mounting table. An opaque pedestal 33 in which the center is cut out in a circular shape and a hole 36 is formed is provided. A transparent glass plate 32 is placed on the pedestal 33,
The crystal blank 21 is placed at a predetermined position on the transparent glass plate 32 corresponding to 6. The ring light 22 is disposed below the pedestal 33 so as to surround the hole 36 of the pedestal 33. A ring-shaped diffusion plate 23 for diffusing light emitted from the ring light 22 to the crystal blank 21 and irradiating the crystal blank 21 with scattered light is disposed radially inward of the ring light 22.

The ring light 22 is provided with a light shielding plate 35,
Light can be irradiated from the entire circumferential direction of the side surface of the crystal blank 21 at an irradiation angle within a range of ± 30 ° with respect to the substrate surface of the crystal blank 21. As described above, since the transparent glass plate 32 having no base pattern is used for the mounting table, the SN ratio is high and the inspection accuracy can be further improved. In addition, since the ring light 22 is arranged below the pedestal 33 so that an obstacle when moving the crystal blank 21 does not come to the upper side, it is possible to cope with mass production of the inspection process. By the way, in the first embodiment, since the transparent glass plate 32 having a smooth surface is used for the mounting table on which the crystal blank 21 is mounted, the crystal blank 21 also having a smooth surface is attracted and does not separate. There is a risk.

Therefore, in the second embodiment shown in FIG. 9, the mounting table is replaced with a frosted glass 34 as a diffusion mounting table instead of the transparent glass, and the diffusion plate covering the front of the ring light 22 is omitted. I have. In order to form the optimal frosted glass 34 for the crystal blank 21 having a high hardness, the surface is roughened by sand rubbing, for example, so that the crystal blank 21 is not adsorbed and scattered light is formed. wear. Unevenness on the surface may be indistinguishable from scratches on the quartz blank as it is. Further, since the quartz blank 21 is harder than glass, the frosted glass 34 is easily scratched. Therefore, the surface is treated with hydrofluoric acid to smooth the irregularities so as to be distinguished from scratches on the crystal blank, and then deoxidized so as to oppose the hard crystal to increase the hardness. The method of forming the frosted glass is not limited to the above method, and may be performed by another method. However, the transmittance is set to be 60% or more in the deoxidized state. In the present embodiment, the mounting table is
By doing so, the adsorption of the quartz blank 21 can be avoided, so that the movement on the frosted glass 34 becomes easy, and it is possible to easily cope with mass production. Further, since the diffusion plate can be omitted, the configuration can be simplified.

FIG. 10 shows a third embodiment. First
The difference from the second embodiment is that the ring light 22 is arranged above the crystal blank 21, the mounting table on which the crystal blank 21 is mounted is omitted, and the ring light 22 is directly mounted on the pedestal 33. Since the scattered light is irradiated from above the crystal blank 21, the pedestal 33 does not need to be transparent. This is effective when there is no space below the pedestal 33 and it cannot be used effectively.

FIG. 11 shows a fourth embodiment. Third
The difference from the first embodiment is that a ring-shaped carrying case 39 for accommodating the crystal blank 21 therein is used.
This is a point that a light shielding plate that covers a part of the ring light 22 is omitted. That is, the carrying case 39 has a two-tiered structure of upper and lower parts, and the lower part is composed of the transparent ring 37 and the upper part is composed of the opaque ring 38. Also, the pedestal 33 on which the crystal blank 21 is placed is made opaque. Therefore, the transparent ring 3
The light emitted from the ring light 22 arranged on the outer periphery of 7 is
Only the light in the horizontal direction, which can enter the inside from the transparent transparent ring 37 sandwiched between the opaque pedestal 33 and the opaque ring 38, is irradiated on the quartz blank 21 in the carrying case 39.

Therefore, by appropriately setting the thickness of the transparent ring 37, the light incident on the carrying case 39 can be shifted by + 30 ° with respect to the surface of the quartz blank 21 without providing the ring light 22 with a light shielding plate. Irradiation can be performed at an irradiation angle within the range. Further, since the upper opaque ring 38 of the carrying case 39 is made light-blocking, it is possible to easily prevent intrusion of disturbance light. By the way, in this case, the thickness of the transparent ring 37 constituting the lower stage of the carrying case 39 is about 0.5 mm to 1 mm. It is difficult to transmit light through the transparent ring 37 simply by irradiating light from outside the thin transparent ring 37.

Therefore, in order to actually embody the fourth embodiment, a plurality of optical fibers 40 having a common light source are used as illumination means as shown in FIG.
The light emitted from the emission end of the optical fiber 40 is converged by passing through the rod lens 41, and the converged light is made to enter the thin transparent ring 37. In the illustrated example, two optical fibers 40 are prepared by being shifted by 60 to 90 degrees in the horizontal direction, and a semicircular mirror 42 is prepared on the opposite side to reflect light emitted from the optical fibers 40. , To simplify the configuration.

As described above, according to the present embodiment, the following effects can be obtained.

(1) Scratches and defects inside and outside the crystal blank can be detected by evaluating the output intensity or distribution of the detection light.

(2) One camera and one light source are simple and inexpensive, and the scratches existing in the quartz blank can be optically emphasized, so that a large dynamic range can be obtained.

(3) Since a single camera captures an image of the quartz blank from directly above, a stable image can be obtained with a constant focus on the entire quartz blank.

(4) The whole can be obtained as one image, and the image is taken from right above, so that the external dimensions of the crystal blank can be obtained with high accuracy.

(5) Since all are processed and inspected in one imaging, high-speed processing is possible.

In the above embodiment, the diffusion plate is formed separately from the ring light, but may be integrated with the ring light. If the light emitted from the ring light is sufficiently scattered light, it may be omitted. Further, the case where the transparent substrate is a quartz blank has been described, but the present invention is not limited to the quartz blank. Any transparent substrate can be used.

[0055]

FIG. 13 shows an experimental example of a circular quartz crystal blank.
The size of the circular quartz blank is usually 3 mm to 76 m.
mφ. The bright line (image) running radially inward from one point on the outer periphery of the crystal blank indicates a scratch having a width of 5 μm. When the measured emission line is not damaged, the light energy distribution has peaks only at the edges at both ends (a). When the measured emission line is scratched, a peak of the light energy distribution occurs at the intersection regardless of the direction of the emission line (b, c). From this, it can be seen that the presence or absence of a flaw can be determined by examining the light energy distribution between the edges. Also, since the outer periphery (edge portion) of the quartz blank is also shining, it can be seen that the outer dimensions can be measured.

FIG. 14 shows that the state of the scratch image does not change even if the direction of the quartz blank is changed. It does not change even if the direction is changed by 360 °. From this, it can be seen that the scratch can be detected accurately and stably.

[0057]

According to the present invention, since the transparent substrate is irradiated with scattered light from all around, the scratch can be optically emphasized with respect to the scratch in any direction, so that the inspection of the scratch can be surely performed. it can. In addition, since the entire transparent substrate can be imaged and image-processed with the entire field of view at once, all the scratches on the transparent substrate can be inspected easily and at high speed, and the inspection by image processing can be automated. It will be easier.

Further, since it can be constituted by one imaging means and one illumination means, the construction is simpler than that of the conventional switching type. Further, since the imaging means is arranged at a position where the imaging direction is perpendicular to the substrate surface of the transparent substrate, the size of the scratch or the transparent substrate can be accurately measured without requiring a complicated correction process.

[Brief description of the drawings]

FIG. 1 shows a principle diagram of a transparent substrate flaw inspection apparatus of the present invention.

FIG. 2 is an explanatory view showing a light irradiation state of the present invention.

FIG. 3 is an explanatory diagram showing a detection state of a flaw according to the present invention.

FIG. 4 is an explanatory diagram of a crystal blank used for finding an optimum irradiation angle.

FIG. 5 is an explanatory diagram of changing an irradiation angle using an optical fiber light source.

FIG. 6 is a diagram showing changes in reflected light images of a quartz blank and a flaw when the light irradiation angle is changed.

FIG. 7 is a plot diagram of a light energy amount with respect to a light irradiation angle.

FIG. 8 is a configuration diagram of a main part showing the first embodiment of the present invention.

FIG. 9 is a configuration diagram of a main part showing a second embodiment.

FIG. 10 is a configuration diagram of a main part showing a third embodiment.

FIG. 11 is a configuration diagram of a main part showing a fourth embodiment.

FIG. 12 is a configuration diagram of a main part that embodies a fourth embodiment;

FIG. 13 is an explanatory diagram showing an image of a circular quartz crystal blank and light energy distribution on a measurement bright line according to the present embodiment.

FIG. 14 is an explanatory diagram showing that the state of a scratch image does not change even if the direction of a circular quartz crystal blank according to another embodiment is changed.

FIG. 15 is an explanatory diagram of a conventional flaw detection device.

FIG. 16 is an explanatory diagram of another conventional flaw detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Quartz blank 22 Ring light (illumination means) 23 Diffusing plate 24 Microscope 25 CCD camera 26 Imaging means 27 Image input means 28 Feature extraction means 29 Judgment means θ Irradiation angle

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01N 21/84-21/90

Claims (5)

(57) [Claims] 1. A transparent substrate for capturing an image of a transparent substrate irradiated with light by an imaging means, extracting characteristics of a flaw existing on the transparent substrate from a captured image signal, and determining the presence of a flaw based on the extracted signal. Irradiating means for irradiating the transparent substrate with light at an irradiation angle within the range of ± 30 ° with respect to the substrate surface of the transparent substrate, and light irradiating the transparent substrate from the illuminating means. A transparent plate for diffusing light and irradiating the transparent substrate with scattered light; and an imaging means arranged at a position where an imaging direction is perpendicular to a substrate surface of the transparent substrate. apparatus. 2. A transparent substrate for capturing an image of a transparent substrate irradiated with light by an imaging means, extracting characteristics of a flaw present on the transparent substrate from a captured image signal, and determining the presence of a flaw based on the extracted signal. In the flaw inspection device, the transparent substrate is placed horizontally, and the light radiated from below the transparent substrate is diffused and the scattered light is irradiated on the transparent substrate. The transparent substrate placed on the diffusion mounting table is provided with a distance of 0 from the peripheral surface of the transparent substrate to the substrate surface of the transparent substrate.
A ring-shaped illuminating means for irradiating light at an irradiation angle in the range of ° to -30 °, and a light-emitting element arranged at a position directly above the imaging direction perpendicular to the substrate surface of the transparent substrate mounted on the diffusion mounting table Inspection apparatus for a transparent substrate, comprising: an imaging unit; 3. A transparent substrate for capturing an image of a transparent substrate irradiated with light by an image pickup means, extracting characteristics of a flaw present on the transparent substrate from a captured image signal, and determining the presence of a flaw based on the extracted signal. In the flaw inspection device of the above, a mounting table on which the transparent substrate is mounted horizontally, and a mounting table provided on the mounting table and having 0 ° with respect to the substrate surface of the transparent substrate from all circumferential directions of the side surfaces of the transparent substrate mounted on the mounting table ° to +
A ring-shaped illuminating means for irradiating light at an irradiation angle within a range of 30 °, a diffusion plate for diffusing light illuminating the transparent substrate from the ring-shaped illuminating means and irradiating the transparent substrate with scattered light; A transparent substrate flaw inspection apparatus, comprising: an image pickup unit disposed at a position directly above the image pickup direction perpendicular to the substrate surface of the transparent substrate placed thereon. 4. A transparent substrate for capturing an image of a transparent substrate irradiated with light by an imaging means, extracting characteristics of a flaw present on the transparent substrate from a captured image signal, and determining the presence of a flaw based on the extracted signal. An opaque mounting table for horizontally mounting a transparent substrate, a transparent ring mounted on the mounting table so as to surround the transparent substrate mounted on the mounting table, and transmitting light, An opaque ring placed on the ring to block light; a ring-shaped illuminating unit arranged around the transparent ring to irradiate light to the transparent substrate via the transparent ring; and illuminating the transparent substrate from the illuminating unit. A diffusion plate for diffusing light and irradiating the transparent substrate with scattered light; and an imaging unit arranged at a position directly above the imaging direction perpendicular to a substrate surface of the transparent substrate mounted on the mounting table. Between the opaque mounting table and the opaque ring Light incident on the ring from the ring-shaped illuminating means via the transparent ring is irradiated on the transparent substrate at an irradiation angle within the range of 0 ° to + 30 ° from the entire circumferential direction of the side surface of the transparent substrate. A flaw inspection device for a transparent substrate in which the thickness of the transparent ring is set as described above. 5. An apparatus according to claim 1, wherein said transparent substrate is a crystal blank for a crystal unit.