JPH07306152A - Optical distortion inspecting device - Google Patents

Abstract

PURPOSE:To provide an optical distortion inspecting device which can perform accurate evaluation without variation and, at the same time, quantitatively express the range of optical distortion of an object to be inspected having a light transmitting property by inspecting the object for optical distortion by quantitatively extracting the distortion. CONSTITUTION:An object W to be inspected, slit 3, and plane of projection 5 are successively arranged in the projecting direction of illuminating light emitted from a light source unit 2. Since part of the light emitted from the unit 2 is intercepted by the slit hole of the slit 3 arranged between the unit 2 and object, the light is passed through the object W and projected upon the plane 5. The picture of the projected image is taken with a picture inputting section 6 and picture signals are outputted to a picture processing section 7. The section 7 divides the inputted picture signals into a plurality of parts, discriminates the presence/absence of distortion based on the degree of variation of the gradation level of each picture element in each part, and finds the ratio of the area of distorted part to the whole area of gradation picture.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical distortion inspection device for inspecting an optical distortion of a translucent inspection object.

[0002]

2. Description of the Related Art Conventionally, regarding this type of inspection apparatus,
As an apparatus for inspecting defects on the surface of an object to be inspected
The one disclosed in JP-A-287053 is known. In this device, an optical bandpass filter having a peak transmittance in the vicinity of the wavelength where the absorption difference between the normal portion and the defective portion of the inspection object is the minimum, and an optical bandpass filter having the peak transmittance in the vicinity of the maximum wavelength. Pixels are subtracted between two images picked up alternately to extract the image of the defective portion, and the presence or absence of the defect is determined based on the area of this portion.

[0003]

However, in such a conventional apparatus, even if an optical distortion of an inspected object having a light-transmitting property is to be inspected, due to the property of the inspected object, there is almost no absorption difference due to a wavelength change of the light source. Since it does not occur, there is a problem that the distorted part cannot be extracted. In addition, since at least two types of optical bandpass filters must be used, there is a problem that the device including the switching mechanism becomes large in size. The present invention has been made in view of the above problems, and it is possible to inspect an optical distortion of an inspected object having a light-transmitting property by a simple device configuration, and further, an optical distortion of the inspected object that does not cause a small difference in gray level. At the same time, it is an object of the present invention to provide an inspection device capable of quantitatively expressing the range of optical distortion.

[0004]

Therefore, the present invention provides
A light source unit that irradiates the inspection object having translucency with illumination light, a projection surface that projects the illumination light that has passed through the inspection object, and an image input unit that captures the projection surface and generates a grayscale image. And an optical distortion inspection device having an image processing unit that determines the presence or absence of distortion based on the degree of variation in the gray level of the gray image obtained by the image input unit, and the inspection device. An optical distortion inspecting device, characterized in that a slit is provided between the light source unit and the object to be inspected to partially shield the illumination light from the light source unit; and in the inspecting device, the image processing section includes an image input section. It is an image processing unit that divides the grayscale image obtained in step 2 into a plurality of parts, determines the presence or absence of distortion based on the degree of variation in the grayscale level of each part, and obtains the ratio of the distorted part in the entire grayscale image. Light To solve the problems described above by providing distortions testing device.

[0005]

When the light source unit irradiates the inspection object with the illumination light, the illumination light is applied to the inspection object, further passes through the inspection object, and is projected on the projection surface. In the case of using the slit, the illumination light is directly irradiated onto the inspection object, further passes through the inspection object, and is projected on the projection surface. Then
The image input unit captures the projected image and generates a grayscale image. The image processing unit inputs this grayscale image and determines the presence or absence of distortion based on the degree of variation in grayscale level. If a slit is provided between the light source unit and the inspection object,
Illumination light, which is partially shielded by the slit, is applied to the inspection object, further passes through the inspection object, and is projected on the projection surface.
When the image input unit divides the grayscale image obtained by the image input unit into multiple parts and determines the presence or absence of distortion based on the degree of variation in the grayscale level of each part, and when obtaining the ratio of the distorted part in the entire grayscale image The input grayscale image is divided into a plurality of portions, and the presence or absence of distortion is determined based on the degree of variation in the grayscale level of each divided portion. Next, the ratio between the entire portion determined to be distorted in each portion and the entire grayscale image is obtained.

[0006]

FIG. 1 is a plan explanatory view showing a first embodiment of the present invention, FIG. 2 is a front explanatory view showing the first embodiment of the present invention, and FIG. 3 is an explanatory view showing a circular slit. FIG. 4 is an explanatory view showing a rectangular slit, FIG. 5 is an explanatory view of a sample, FIG. 6 is a plan explanatory view of a second embodiment of the present invention, and FIG. 7 is a first explanatory drawing of the present invention. 8 is a front explanatory view of the second embodiment, FIG. 8 is a front explanatory view showing a third embodiment of the present invention, FIG. 9 is a side explanatory view showing the third embodiment of the present invention, and FIG. 11 is an explanatory diagram of an image, and FIG.
Is a front explanatory view of the fourth embodiment of the present invention, FIG. 12 is a front explanatory view of the fourth embodiment of the present invention, and FIGS. 13 and 14 are plan explanatory views showing a method of placing a sample. .

A first embodiment of the present invention will be described below with reference to FIGS. 1 to 5. 1 is an optical distortion inspection device, W
Is a sample. The optical distortion inspection device 1 inspects the optical distortion of the sample W. In this embodiment, the sample W is composed of a glass plate W1 and an intermediate film W2 which is an object to be inspected, as shown in FIG. The interlayer film W2 to be inspected in this example is an interlayer film used for a windshield of an automobile or the like, and is used by being sandwiched between the glass plates W1 at the time of use. Inspect with the product sandwiched between. Although the intermediate film is inspected in this embodiment, the inspection is not limited to the intermediate film as long as the inspection purpose is detection of optical strain. The sample W to be inspected in this embodiment has a relatively small optical strain size and a relatively large density difference in the distorted portion, so that the sample W is placed without tilting with respect to the illumination light. The optical distortion inspection device 1 includes a light source unit 2, a slit 3, a sample placement unit 4, a projection surface 5, an image input unit 6, an image processing unit 7, a gantry 8 and an evaluation unit 9, and the image processing unit 7 and Each of the components other than the evaluation unit 9 is placed on the gantry 8 and is configured to be movable. The optical strain inspection apparatus 1 can mount the sample W on the sample mounting unit 4. The light source unit 2 includes a light emitting unit 21, an optical fiber 22, and an irradiation port 23, and the illumination light emitted by the light emitting unit 21 passes through the optical fiber 22 and is emitted from the irradiation port 23 toward the slit 3. The irradiation port 23 is mounted on one end of the gantry 8 and is movable in the optical axis A direction irradiated from the irradiation port 23. Although the light emitting section 21 is provided with a halogen bulb in this embodiment, it may be light of a specific wavelength, and it is preferable that the image transmitted through the sample W is projected on the projection surface 5 more clearly.

The slit 3 has a slit hole 31 in the center thereof, and is placed between the irradiation port 23 of the light source unit 2 and the sample W to the projection surface 5 installed on the opposite side of the sample W from the light source unit 2. It is installed at a position where the illumination light from is projected and is movable on the gantry 8 in the optical axis A direction. The slit 3 makes it possible to irradiate the sample W with light close to a point light source by passing the light from the irradiation port 23 through the slit hole 31, and the optical distortion of the sample W in the image due to the light transmitted through the sample W is Make it more visible. In this embodiment, the slit 3 is arranged at a position 10 mm from the irradiation end of the irradiation opening 23, and the shape of the slit hole 31 is a circular slit hole 31 or a rectangular slit hole 31, as shown in FIG. In the example, the circular slit hole 31 has a circular shape with a diameter of 0.1 mm. Further, the rectangular slit 3 shown in FIG. 4 is effective when the optical strain of the sample W has directionality, and in this embodiment, it is 0.19 mm × 0.5 mm.
The rectangular slit hole 31 of When the direction of optical distortion and the longitudinal direction of the rectangular slit 3 coincide with each other, the light-dense state of the light on the projection surface is emphasized, and it is possible to clearly represent the circular slit 3 or more. 3 is used so that the longitudinal direction thereof coincides with the optical strain direction. Of course, the size of the slit 3 depends on the shape of the irradiation port 23,
The position is determined in consideration of the positional relationship between the irradiation port 23, the sample W, and the projection surface 5.

The sample placing section 4 is capable of placing the sample W substantially perpendicularly to the optical axis A, and is movable on the mount 8 in the optical axis A direction. As shown in FIG. 1, the projection surface 5 is arranged so as to be inclined with respect to the sample W at an angle θ in the direction of the image input unit 6, and projects an image by the illumination light from the irradiation port 23 passing through the slit 3 and the sample W. In this embodiment, the angle θ is 105 °. Further, the projection surface 5 is preferably a white paper or the like having no gloss and less unevenness. The image input unit 6 is composed of a CCD camera, captures an image projected on the projection surface 5, converts the brightness of the projected image into a signal, and outputs the image as a grayscale image signal to the image processing unit 7.
Output to. The gantry 8 is composed of a main body 81 and an arm 82, and an arm 82 on which the image input unit 6 can be placed is installed so as to be movable in the longitudinal direction of the main body 81 from an intermediate portion of the main body 81. As described above, the respective positional relationships from the plane direction shown in FIG. 1 are such that the slit 3, the sample mounting portion 4, and the sample W are substantially perpendicular to the optical axis A of the illumination light emitted from the irradiation port 23. The projection surface 5 is placed at an angle θ, and the image input unit 6 is placed so that the imaging direction is substantially perpendicular to the projection surface 5.
Further, the respective positional relationships from the front direction shown in FIG. 2 are as follows: the slit 3 is substantially perpendicular to the optical axis A, the specimen W has an inspection surface substantially perpendicular to the optical axis A, and the projection surface 5 has the projection surface optical axis. The image input unit 6 is mounted on the arm 82 so that its image pickup direction is the optical axis A direction substantially perpendicular to A. The image processing unit 7 inputs the signal of the grayscale image from the image input unit 6, and outputs the dispersion value of the density values between the pixels of the captured grayscale image. In the grayscale image, when the sample W has a large distortion, the difference in the refractive index also becomes large, so that the stripe pattern formed also has a large difference in light and shade, and when the distortion is small, the difference in the refractive index becomes small. Therefore, it becomes a fine striped pattern in which the difference in brightness is not so clear. Further, in this embodiment, the strain due to the intermediate film W2 appears in the horizontal direction, and the strain due to the glass plate W1 appears in the vertical direction.

The variance value is calculated by calculating the variance value for one column in the vertical direction from the density value of each pixel of the grayscale image, and similarly for the other columns, and taking the average thereof. There are various methods of obtaining the variance value, and the variance value of the entire grayscale image may be calculated. However, by calculating the above-described vertical or horizontal direction as one unit, it is possible to detect the optical distortion to be inspected. Is more effective. That is, in this embodiment, since the optical distortion of the intermediate film W2 is inspected, the vertical distortion is calculated in order to eliminate the influence of the optical distortion due to the glass plate W1, but the inspection target is the optical distortion of the glass plate W1. In such a case, the dispersion value can be calculated in the lateral direction, and the influence of the optical strain of the intermediate film W2 can be eliminated. Further, it is not necessary to target the entire grayscale image, and the variance value may be calculated only for a specific part. For example, with respect to a portion where optical distortion is likely to occur, one or a plurality of regions having a predetermined size are set, and the variance value is calculated for the region. This reduces the amount of calculation. An evaluation unit 9 evaluates the quality of the sample W by comparing the variance value calculated by the image processing unit 7 with the variance value within a predetermined allowable range. Although not described in this embodiment,
When the sample W is placed and removed by a robot or the like, it is possible to automatically classify the sample W into a non-defective product or a defective product after removing it according to the result evaluated by the evaluation unit 9.

Next, the operation of this embodiment will be described. The sample W is placed on the sample placing section 4. Next, illumination light is generated by the light emitting unit 21 of the light source unit 2, passes through the inside of the optical fiber 22, and irradiates the sample W from the irradiation port 23. The illumination light is irradiated in the direction of the sample W, the portions other than the slit holes 31 are shielded by the slits 3, the sample W is transmitted, and the image transmitted through the sample W in the shape of the slit holes 31 is enlarged and projected on the projection surface 5. At this time, in the projected image, when the inspection object W2 of the sample W has optical distortion such as unevenness, the illumination light is refracted at the distortion portion. This refracted illumination light passes through the slit 3
Is not present, and when irradiation is performed over a wide range such that the irradiation range uniformly covers the entire intermediate film W2, the illumination light and the like that are irregularly refracted at other portions and the refraction that occurs at the distorted portion of the inspection object W2. And the illumination light from the two influence each other, and do not cause a very large density difference. However, the slit 3 is provided at a position close to the irradiation port 23.
Is installed, and the illumination light emitted by passing through the slit holes 31 with a minute interval becomes irradiation light from a pseudo point light source without being affected by other refracted light, and reaches the intermediate film W2, By irradiating only a part of the intermediate film W2, the optical distortion is enlarged and projected on the projection surface 5 as a striped pattern having light and shade with a difference in brightness. In this way, the illumination light passes through the slit hole 31 and becomes irradiation light from a pseudo point light source.

The image due to the difference in brightness projected on the specimen W in this way is picked up by the image input unit 6. The image input unit 6 outputs the image projected on the projection surface 5 as an image signal and inputs the image signal to the image processing unit 7. The image processing unit 7 calculates the variance value from the density value of each pixel of the grayscale image,
Output to the evaluation unit 9. In the evaluation unit 9 that inputs the variance value,
The quality of the sample W is evaluated by comparing the input variance value with the variance value within a predetermined allowable range. Further, the light source unit 2 emits illumination light close to a point light source or a line light source,
If the illumination light equivalent to the case where the slit 3 is used can be irradiated, the inspection can be performed without using the slit 3.

As a second embodiment, the case of illuminating the same illumination light as that using the slit 3 with the light source unit 2 will be described with reference to FIGS. 6 and 7. In this embodiment, the light source unit 2 includes a light emitting section 21, an irradiation opening 23, and an illumination light generating section 24.
And is installed at one end of the main body 81 of the gantry 8. The light emitting section 21 generates illumination light as in the first embodiment. In the illumination light generation unit 24, the illumination light generated by the light emitting unit 21 is deflected by an optical device such as a lens, and the same illumination light as that using the slit 3 is emitted. The irradiation port 23 can irradiate the specimen W with the illumination light and project it onto the projection surface 5 as in the first embodiment. The sample placement unit 4, projection plane 5, image input unit 6, image processing unit 7, and evaluation unit 9 are the same as in the first embodiment. The operation of this embodiment is similar to that of the first embodiment, but since the slit 3 is not provided, the illumination light to be emitted directly passes through the sample W and is projected on the projection surface 5. The operation of the projection plane 5, the image input unit 6, the image processing unit 7, and the evaluation unit 9 will be first described.
It is similar to the embodiment. In the first and second embodiments, the sample W has a relatively small optical strain size and a relatively large grayscale difference in the strained portion, but the optical strain size is large. When inspecting a sample W having a relatively large grayscale difference and a small grayscale difference in the distorted portion, the grayscale difference in the optically distorted portion is emphasized for more accurate inspection.

A third embodiment will be described below with reference to FIGS. 8 and 9 as an embodiment for inspecting a sample W having a relatively large optical distortion size and a small difference in density of a distorted portion. In this embodiment, the slit 3 is not used as in the second embodiment, and the light source unit 2, the sample placement unit 4, the projection surface 5, the image input unit 6, the image processing unit 7, and the evaluation unit 9 are used.
Are installed independently of each other without using the gantry 8. The light source unit 2 includes a light emitting unit 21 and an irradiation port 23, and the light emitted from the light emitting unit 21 is emitted from the irradiation port 23 in the direction of the projection surface 5. Although the light emitting unit 21 is provided with a high pressure mercury lamp in this embodiment, it may be light of a specific wavelength or light of a specific wavelength, and the light transmitted through the sample W causes the image of the sample W to be projected on the projection surface 5. Pseudo-parallel light is desirable so that optical distortion can be projected more clearly. The quasi-parallel light used in this embodiment is not a light flux in which the light fluxes are completely parallel, but a light flux light that is emitted by collecting emitted light rays at a certain expansion ratio. Of course, it is possible to use parallel light flux light having an area equivalent to that of the projection surface 5.

The sample mounting section 4 can mount the sample W at an angle θ1 with respect to the optical axis A. In this embodiment, the sample mounting unit 4 mounts the sample W at a fixed angle of 20 degrees with respect to the optical axis A. The sample W to be tested in this example has a relatively large optical strain size and a small grayscale difference in the distorted portion. Therefore, the illumination light is pseudo-parallel light and the sample W is tilted with respect to the illumination light. By placing it, the optical distortion in the tilted direction is suppressed and suppressed by the influence of the light refracted from other parts, and the contrast of the image becomes clear. In the present embodiment, the sample W is provided with an angle in order to emphasize the degree of distortion of the sample W, but this is not a limitation depending on the nature of the sample W, and the sample W may be placed at an appropriate angle. Further, when the difference in optical strain of the sample W is relatively large and the size of the optical strain is relatively large, the sample W may be installed without tilting.
The projection surface 5 is arranged substantially perpendicular to the optical axis A with respect to the sample W as shown in FIG. 8, and projects an image of pseudo-parallel light from the irradiation port 23 passing through the sample W. The image input unit 6 is composed of a CCD camera, captures an image projected on the projection surface 5, converts the brightness of the projected image into a signal, and outputs the signal as a grayscale image signal to the image processing unit 7.

The image processing unit 7 receives the signal of the grayscale image from the image input unit 6 and obtains the variance from the density value of each pixel for each portion obtained by dividing the captured grayscale image,
Each obtained dispersion value is compared with a predetermined dispersion value, and the ratio of the divided portion having distortion to the entire grayscale image to be judged is output to the evaluation unit 9. Although various methods of dividing the grayscale image into a plurality of parts are conceivable, in this embodiment, the grayscale image is divided into every 5 pixels in the vertical and horizontal directions in a grid pattern. That is, as shown in FIG. 10, the XY direction of each portion a is divided so as to include pixels of X0 to X4 and Y0 to Y4. In this embodiment, the number of pixels is set to 5 pixels, but it may be set appropriately depending on the magnitude of distortion or the like. The calculation of the variance value of the divided part a is performed in the vertical direction from the density value in pixel units of the grayscale image in each divided part a (pixels in rows Y0 to Y4 in column X0).
For the other columns (columns X1 to X4) and take the average thereof (average variance value of columns X0 to X4) to obtain the average as the variance value of the divided portion. Of course, it is also possible to calculate in the horizontal direction (columns X0 to X4 in each row Y). When the variance value of the portion a thus obtained is equal to or larger than a predetermined variance value (hereinafter, referred to as a threshold value), it is determined that the portion has distortion. Then, after making the determinations for all the divided portions, the ratio of the divided portions that are determined to have distortion to the entire grayscale image to be determined is obtained. As for the method of obtaining the dispersion value, it is more effective to detect the optical distortion if each division portion is calculated by using the vertical or horizontal direction as one unit as described in the first embodiment. Further, it is not necessary to target the entire grayscale image, and it may be a part. For example, for a portion where optical distortion is likely to occur, one or a plurality of regions of a predetermined size are set, the variance value of each divided portion is calculated in the same manner as described above for the region, and from the obtained variance value, The ratio of the divided parts determined to have distortion with respect to the entire grayscale image to be determined is obtained. This reduces the amount of calculation.

The evaluation unit 9 compares the ratio of the distorted portion calculated by the image processing unit 7 with the ratio of a predetermined allowable range to evaluate the quality of the sample W. As an evaluation method, ranks are set according to proportions, and the ranks are judged. In addition, the image processing unit 7 outputs the distortion determination result for each divided portion, and the output is input to the evaluation unit 9 to map at which position of the sample W the distortion occurs, and the CRT is displayed.
Alternatively, it can be displayed on a display unit (not shown) such as a printer. Further, when the sample W is placed and removed by a robot or the like, it is possible to automatically classify the sample W based on the evaluation result of the evaluation section 9 and classify it as a good product or a defective product. . In this embodiment, the image processing unit 7 uses the average of the vertical dispersion values of each divided portion as the dispersion value within the divided portion, but the dispersion value of each divided portion is the maximum vertical dispersion value within the divided portion. By setting the value or the minimum value, it becomes possible to set the evaluation standard of the sample W to the maximum value or the minimum value of the grayscale difference of the optical distortion in each divided portion. Further, the image processing unit 7 outputs the ratio between the entire grayscale image and the distorted portion, but the evaluation unit 9 may output the maximum value among the variance values obtained from each divided portion, and the evaluation unit 9 may determine the rank from the maximum value. It is possible. This method is effective when the density difference of the distorted portion is used as the determination reference regardless of the ratio of the existing optically distorted portion and the entire grayscale image. Furthermore, while outputting the ratio between the entire grayscale image and the distorted part, the maximum value among the variance values obtained from each divided part is also output, and by using the ratio between the distorted part and the entire grayscale image as an evaluation criterion, For example, if the ratio of the distorted part to the entire grayscale image is less than 10%, the one having the maximum variance value of the divided parts of 15 or more is a defective product, and the ratio of the distorted part to the entire grayscale image is 10% or more. When it is less than 25%, the maximum value of the variance value of the divided portion is 10 or more is a defective product, and the standard of the variance value determined to be a defective product is changed depending on the ratio of the distorted portion and the entire grayscale image. It becomes possible to judge.

In this embodiment, the variance value of the divided portions is compared with the threshold value to determine the presence / absence of distortion in each divided portion to obtain the ratio of the distorted portion in the entire grayscale image. Without changing the threshold value, the threshold value is changed so that the ratio between the entire grayscale image and the distorted portion is, for example, 10%, and the threshold value when the threshold value is 10% is an evaluation target. It is also possible to classify less than B rank, less than 10 and less than 15 less than C rank, and 15 or more as defective. The sample W to be inspected in the above-described embodiment has a relatively large optical strain size and a small difference in the density of the strained portion. The inspection was performed so that the optical distortion in the tilted direction was compressed and emphasized so that the grayscale difference of the image was clearly shown. The method of evaluating a grayscale image by dividing it into a plurality of parts as described above may of course be used in the first and second embodiments. Further, as in the case of the third embodiment, the specimen W may be placed with an inclination with respect to the optical axis A in the first and second embodiments, and in this case as well, the specimen W is inclined as in the third embodiment. The optical distortion in the direction is compressed and emphasized, so that the difference in grayscale of the image appears clearly.

As a fourth embodiment, a case in which the sample W is placed in the apparatus of the first embodiment while being tilted with respect to the optical axis A will be described with reference to FIGS. 11 to 14. Of course, slit 3
In the second embodiment in which the omission is omitted, it is possible to mount the device in a tilted manner. In this embodiment, the light source unit 2, the slit 3, the projection surface 5, the image input unit 6, the image processing unit 7, and the evaluation unit 9 are the first except that the sample W is placed at an angle with respect to the optical axis A. The same as in the example, but since the difference in shade of the sample W is small, the slit 3 is moved away from the light source unit 2 and the sample W is placed close to the projection surface 5, and the irradiation light is light with a high degree of parallelism. Therefore, it is desirable that the grayscale difference of the projected image can be clearly seen. Therefore, it is conceivable that the light source unit 2 in the second embodiment uses an optical system device such as a lens to adjust the parallelism of the irradiation light.

The sample W is arranged at an angle α with respect to the optical axis A as shown in FIG. The smaller the angle α, the more the optical distortion in the inclined direction is compressed and emphasized. In the operation of this embodiment, as shown in FIG. 11, the specimen W is tilted with respect to the optical axis A, and the distortion in the horizontal direction is compressed and emphasized and projected onto the projection surface 5. Therefore, even a small optical distortion can be projected on the projection surface 5 as an image, and the presence or absence of distortion can be determined. Other functions are similar to those of the first embodiment. When the sample W is not a flat plate as in the above-mentioned embodiment but a lump or a curved plate and the surface having optical distortion is not flat, the tangent line at the point to be inspected on the surface is inclined with respect to the optical axis A. It can be placed and inspected.

FIG. 13 is a plan view showing a mounting method for inspecting a curved plate such as an automobile windshield. The sample W is attached to the gantry 8 via the sample placing section 4. At this time, when it is desired to inspect the optical distortion of the point B on the sample W, the tangent line C of the sample W at the point B and the optical axis A may be placed so that the angle α is maintained. FIG. 14 is a plan view showing a mounting method for inspecting a lump-like object such as a weight stone used as a decoration on a desk. When it is desired to inspect the optical distortion at the point B of the sample W as in the example shown in FIG. 13, consider the tangent line C of the sample W at the point B, and place the sample W so that the tangent line C and the optical axis A maintain the angle α. Good. In this case, the action is similar to the example shown in FIG. 13, and the surface having the optical strain of the sample W is tilted with respect to the optical axis A, and the horizontal strain is compressed and emphasized and projected onto the projection surface 5. To be done. Therefore, even a slight optical distortion of light and shade can be projected as an image on the projection surface 5, and the presence or absence of distortion can be determined.

[0022]

As described above, according to the present invention, it is possible to quantitatively inspect the optical distortion of a translucent object such as a film-like object with a simple configuration and the presence or absence of distortion. At the same time, since the range of strain can be inspected quantitatively, it is possible to inspect with less variation. It is also possible to inspect the optical distortion of the object to be inspected, which does not cause a small contrast difference.

[Brief description of drawings]

FIG. 1 is an explanatory plan view showing a first embodiment of the present invention.

FIG. 2 is a front view showing the first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing the shape of a slit.

FIG. 4 is an explanatory diagram showing the shape of a slit.

[Fig. 5] Illustration of specimen

FIG. 6 is an explanatory plan view showing a second embodiment of the present invention.

FIG. 7 is a front view showing the second embodiment of the present invention.

FIG. 8 is a front view showing the third embodiment of the present invention.

FIG. 9 is a side view showing the third embodiment of the present invention.

FIG. 10 is an explanatory diagram of a grayscale image.

FIG. 11 is an explanatory plan view showing a fourth embodiment of the present invention.

FIG. 12 is an explanatory front view showing a fourth embodiment of the present invention.

FIG. 13 is an explanatory plan view showing a method of placing a sample.

FIG. 14 is an explanatory plan view showing a method of placing a sample.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical distortion inspection device 2 Light source unit 21 Light emitting part 22 Optical fiber 23 Irradiation port 24 Illumination light generating part 3 Slit 31 Slit hole 4 Sample placement part 5 Projection surface 6 Image input part 7 Image processing part 8 Frame 81 Main body 82 Arm 9 Evaluation department

Claims (3)

[Claims] 1. A light source unit for irradiating a light-transmitting inspection object with illumination light, a projection surface for projecting the illumination light transmitted through the inspection object, and an image of the projection surface to obtain a grayscale image. An optical distortion inspecting apparatus, comprising: an image input unit to be generated; and an image processing unit that determines presence / absence of distortion based on a degree of variation in gray level of a gray image obtained by the image input unit. 2. The optical distortion inspection apparatus according to claim 1, wherein a slit is provided between the light source unit and the object to be inspected to partially shield the illumination light from the light source unit. 3. The image processing section divides the grayscale image obtained by the image input section into a plurality of pieces, and judges the presence or absence of distortion based on the degree of variation in the grayscale level of each part, and there is distortion in the entire grayscale image. The optical distortion inspection apparatus according to claim 1 or 2, wherein the proportion of the portion is obtained.