JPH10246706A - Optical member inspecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical member inspecting apparatus for deciding pass- fail of a non-defective object and defective object according to an objective reference. SOLUTION: An imaging element 5 is a line sensor. An imaging lens 4 is a positive lens system having an optical axis passing a center of a pixel row of the element 5. An optical member 9 to be inspected is disposed at a position conjugate with the element 5 regarding the lens 4. Peripheral edge light beams (m) of a light incident to each pixel of the element 5 are crossed on a surface of the member 9. A shielding plate 8 shields between the beams (m) at a rear side of the member 9. A diffusing plate 2 is disposed at a predetermined distance from the rear surface of the member 9. An illumination lamp 1 emits the plate 2 from the rear side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical member inspection apparatus for detecting an optical defect such as an abnormal shape of an optical member such as a lens.

[0002]

2. Description of the Related Art An optical member such as a lens or a prism is used to refract an incident light beam regularly or to travel in parallel.
It is designed to converge or diverge at one point or linearly. However, when forming the optical member, lint or the like is mixed into the optical member (so-called “burr”), scratches or the like are generated on the surface of the optical member due to human handling after molding, and dust is generated. If it is attached, the incident light beam will be disturbed, so that desired performance cannot be obtained.

[0003] Therefore, in order to detect these optical defects, a sensory inspection by human eyes using a fluorescent lamp, a light source for a slide projector, or the like has been conventionally performed.
A sensory test using a fluorescent lamp or a light source for a slide projector is a method in which light emitted from a fluorescent lamp or a light source for a slide projector is applied to an optical member, and the surface of the optical member is observed from outside the optical path. This is to recognize the luminance of the defective part by comparing it with the luminance of the background, taking into account refraction and the like.

[0004]

However, in the sensory inspection by human eyes, there is no objective criterion for determining a good product or a defective product. Therefore, when the inspection is performed by a plurality of persons, the judgment criteria of the quality vary for each person to be inspected. In other words, good products were discarded as defective products, causing waste. Also, even when the same person performs the inspection, the criterion tends to be stricter as the user becomes accustomed,
A good product was often determined to be defective.

[0005] In view of the above problems, an object of the present invention is to provide an optical member inspection apparatus capable of performing a pass / fail judgment of a good product and a defective product according to an objective standard.

[0006]

The invention described in each claim is
It has been made to solve the above problems. The invention according to claim 1 is an optical member inspection apparatus for detecting an optical defect of an inspection target optical member, wherein an imaging lens and an imaging device arranged at a position substantially conjugate with the inspection target optical member with respect to the imaging lens. An element, and an illumination unit that illuminates a portion of the inspection target optical member where the light is transmitted from outside an optical path of light incident on the imaging device after passing through the inspection target optical member and entering the imaging lens, Numerical means for quantifying a portion indicating an optical defect of the optical member in the image captured by the image sensor, and whether or not the numerical value quantified by the numerical means exceeds a predetermined determination reference value And determining means for determining

According to the optical member inspection apparatus thus configured, the illuminating means is located outside the optical path of light incident on the imaging device after passing through the inspection target optical member and entering the imaging lens. ing. Therefore, the illumination light that has entered the inspection target optical member from the illumination means does not enter the imaging device after entering the imaging lens unless the inspection target optical member has an optical defect. Therefore, an image captured by the imaging device is entirely dark. On the other hand, when there is an optical defect in the imaging target region of the inspection target optical member, illumination light that has entered the imaging target region from the illumination unit is diffused by the optical defect. When a part of the diffused light enters the imaging lens,
Since the diffused light converges on the image sensor, a bright image of an optical defect is captured by the image sensor. Therefore, a bright portion corresponding to an optical defect appears in an image captured by the image sensor.

The optical member to be inspected in the present invention includes a transparent optical member such as a lens, a prism, and a plane-parallel plate.
Therefore, the optical member to be inspected includes those made of glass and those made of resin molding. Optical defects of optical members
It refers to a defect on the surface of the optical member or a defect inside the optical member. Defects on the surface of the optical member include surface scratches, dirt, dust, and the like. In addition, as the defect inside the optical member, burrs and cracks inside the optical member are listed.

The image pickup device may be an area sensor or a line sensor. The digitizing means may calculate the area of a bright place indicating an optical defect of the optical member in the image, may calculate the width, may calculate the luminance, or multiplies these. The calculated value may be calculated.

When there are a plurality of types of numerical values to be digitized by the numerical value converting means, all of the numerical values may be compared with a reference value, or some types of numerical values determined according to the type of the optical member. Only numerical values may be compared.

According to a second aspect of the present invention, the illuminating means of the first aspect is disposed at a position opposite to the imaging lens with respect to the optical member to be inspected, and illumination light is directed toward the optical member to be inspected. A diffusion plate, and a light shielding unit that blocks an optical path of light incident on the image sensor after passing through the inspection target optical member and entering the imaging lens, between the inspection target optical member and the diffusion plate. Has been specified.

The diffusion plate may be a translucent member illuminated from behind or a reflective member illuminated from the front side. The light-shielding means is for preventing light transmitted through the optical member to be inspected from directly entering the image sensor, so long as it shields the area surrounded by the marginal rays of the light beam incident on the image sensor, It may be arranged anywhere between the diffusion plate and the optical member to be inspected. The planar shape may be any shape as long as it can shield at least the area surrounded by the peripheral light beam. Therefore, the planar shape of the light shielding means is a narrow band shape when the image sensor is a line sensor, and a rectangular shape substantially the same as the area sensor when the image sensor is an area sensor. Therefore, in the case of an area sensor, the width of the light blocking means increases as the area of the area sensor increases and the resolution increases, whereas in the case of a line sensor, the length of the line sensor increases. Even if the resolution is increased, the width of the light shielding means does not change. The narrow width of the light-shielding means means that the incident angle of the illumination light hitting the defect portion of the optical member to be inspected becomes small, so that the possibility that the illumination light diffused at the defect portion enters the imaging lens increases. It is.

The light-shielding means may be a light-shielding pattern directly printed on the surface of the diffusion plate, or a plate-shaped opaque member which is appropriately cut out and adhered to the diffusion plate. A light shielding pattern may be printed on the surface of a transparent member separate from the plate.

According to a third aspect of the present invention, there is provided the image sensor according to the second aspect, wherein the image sensor is a line sensor whose scanning direction extends in a certain direction orthogonal to the optical axis of the imaging lens, and the light shielding means expands in the certain direction. By having, it is specified.

According to a fourth aspect of the present invention, the magnification of the photographing lens of the third aspect is adjusted such that the entire width of the optical member to be inspected is imaged by the line sensor.
It is specified.

According to a fifth aspect of the present invention, the light-shielding means of the third aspect has a band shape. With this configuration, the imaging target portion of the inspection target optical member is illuminated from both sides of the light shielding unit, so that there is a higher possibility that the illumination light diffused at the defect location will enter the imaging lens.

According to a sixth aspect of the present invention, in accordance with the fourth aspect, the apparatus further comprises a moving means for moving the optical member to be inspected in a direction orthogonal to a scanning direction of the line sensor, and the line sensor moves the optical member to be inspected. It is specified by imaging at each position and outputting image data for each line. With such a configuration, even when the line sensor is employed as the image sensor for the above-described reason, the inspection can be performed over the entire area of the inspection target optical member.

According to a seventh aspect of the present invention, in the third aspect, an auxiliary illumination device for illuminating a part of the optical member to be inspected, which is imaged by the imaging means, from a side of the light shielding means in the predetermined direction. Is the one identified. With this configuration, even when the length of the light-shielding plate in the longitudinal direction is longer than the width of the inspection-target optical member, the imaging target portion of the inspection-target optical member can be illuminated from the longitudinal direction of the light-shielding plate. Even when the defect has directionality, the illumination light can be diffused at the defect location and incident on the imaging lens.

According to an eighth aspect of the present invention, the digitizing means of the sixth aspect reconstructs image data corresponding to the entire optical member to be inspected based on the image data for each line output from the line sensor. At the same time, the image data is specified by measuring the number of pixels whose luminance exceeds a predetermined threshold value.

According to a ninth aspect of the present invention, there is further provided a rotating means for rotating the optical member to be inspected according to the third aspect around the optical axis of the imaging lens, and the magnification of the taking lens is the diameter of the optical member to be inspected. The whole area in the direction is adjusted to be imaged by the line sensor, and the line sensor specifies the image by inspecting the optical member to be inspected at each position and outputting an image signal for each line. It is.

According to a tenth aspect of the present invention, there is further provided a rotating means for rotating the optical member to be inspected of the third aspect about a rotation axis which is offset from an optical axis of the imaging lens, and the magnification of the photographing lens is adjusted by the inspection. The region from the rotation axis to the outer edge of the target optical member is adjusted so as to be imaged by the line sensor. The line sensor images the inspection target optical member at each of its positions, and image data for each line is obtained. Is output.

The invention according to claim 11 is the invention according to claim 6 or 1.
The digitizing means of 0 outputs 1 output from the line sensor.
It is specified by measuring the length of a portion of the image data for each line where the luminance exceeds a predetermined threshold.

According to a twelfth aspect of the present invention, a ninth or a first aspect is provided.
The digitizing means of 0 outputs 1 output from the line sensor.
The image data of the polar coordinate system corresponding to the entire optical member to be inspected is reconstructed based on the image data of each line, and the image data of the polar coordinate system is converted into an image of the rectangular coordinate system. Is determined by measuring the number of pixels whose luminance exceeds a predetermined threshold.

According to a thirteenth aspect, the present invention provides a ninth or first aspect.
The rotation means 0 is specified by rotating the inspection target optical member about the optical axis of the inspection target optical member. With this configuration, even when inspecting an optical member having a refractive power in the radial direction about the optical axis such as a lens, for example, the shadow due to the light shielding plate does not move on the imaging surface of the imaging device. Imaging can be performed with the element fixed.

According to a fourteenth aspect of the present invention, the light-shielding means of the thirteenth aspect has a band-like shape that expands from a portion intersecting the optical axis of the inspection target optical member toward the end. is there. With this configuration, at a position near the optical axis of the optical member, the incidence angle of the illumination light hitting the defect of the inspection target optical member becomes small, so that the illumination light diffused at the defect may enter the imaging lens. At the position near the peripheral edge of the optical member, the incidence angle of the illumination light hitting the defect portion of the inspection target optical member increases, so that the possibility that the illumination light diffused at the defect portion enters the imaging lens decreases. . That is, the defect detection sensitivity can be increased near the optical axis and reduced near the periphery.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

[0027]

Embodiment 1 A first embodiment of the present invention shows a configuration example of an optical member inspection apparatus suitable for inspecting an optical member having no optical axis such as a plane-parallel plate. <Configuration of Optical Member Inspection Apparatus> The schematic configuration of the first embodiment is shown in FIG. 1 which is a front view and FIG. 2 which is a partial side view. As shown in FIG. 1, the illumination lamp 1, the diffusion plate 2, and the imaging device 3 that constitute the optical member inspection device are arranged on the same optical axis l.

The image pickup device 3 includes an image pickup lens 4 as a positive lens system, and an image pickup device 5 composed of a CCD line sensor for picking up an image with light converged by the image pickup lens 4. In FIG. 1, an image sensor 5
Are arranged so that the pixel rows are oriented in a direction orthogonal to the paper surface. The pixel array of the image sensor 5 intersects the optical axis l of the image pickup lens 4 perpendicularly in the middle. Note that the imaging lens 4 is movable forward and backward with respect to the imaging device 5 in the imaging device 3 (focus adjustment is possible).
The imaging device 3 itself is also mounted on a frame (not shown) of the optical member inspection device so that the imaging device 3 can be advanced and retracted in the direction of the optical axis l.

The image pickup device 5 picks up an image in a line at predetermined time intervals (a period in which electric charges are appropriately accumulated in each pixel), and scans each pixel in the order in which the pixels are arranged to store the image in each pixel. The output charge is output. The charges output from the image sensor 5 in this way are subjected to predetermined amplification processing and A / D conversion processing, and then input to the image processing device 6 as image data composed of luminance signals for one line.

The image processing device 6 is a processor that determines whether the optical member 9 to be inspected is a non-defective product or a non-defective product, and performs predetermined image processing on image data input from the image sensor 5. The numerical value of the degree of the optical defect of the optical member 9 to be inspected is quantified, and the numerical value is compared with a predetermined criterion value (allowable value) to determine whether the numerical value is within the criterion value or exceeds the criterion value. I do. That is, the image processing device 6 corresponds to a digitizing unit and a determining unit. The image processing apparatus 6 also transmits a control signal for moving the inspection target optical member 9 in synchronization with the input of image data from the image sensor 5 in accordance with the above-described determination processing. Output to The image processing device 6 includes an image memory 6a for storing image data when performing the above-described image processing.

The slide table 7 includes a slide rail 7
a, a slider 7b, a drive motor 7e, a boom 7c, and a holder 7d. The slide rail 7a is fixed to a frame (not shown) of the optical member inspection device so as to face a direction orthogonal to the direction of the pixel row of the image sensor 5 and the direction of the optical axis l of the imaging lens 4, respectively. . The slider 7b is provided with a slide rail 7a.
Slide up. The drive motor 7e slides the slider 7b at a constant speed with respect to the slide rail 7a. The boom 7c has a proximal end fixed on the slider 7b and a holder 7d fixed to the distal end. The holder 7d holds the inspection target optical member 9 detachably. When the above-described control signal is output from the image processing device 6, the drive motor 7e rotates according to the control signal, and moves the slider 7b to the slide rail 7a.
To slide along. As a result, the inspection target optical member 9 is moved in the direction of the pixel row of the imaging device 5 and the imaging lens 4.
Are moved at a constant speed in a direction orthogonal to the direction of the optical axis l. That is, the slide table 7 constitutes a moving unit for moving the inspection target optical member 9 in a direction orthogonal to the scanning direction of the image sensor 5.

The inspection target optical member 9 is a plane-parallel transparent transparent plate having a rectangular shape as shown in FIG. The short side of the inspection target optical member 9 is parallel to the pixel row of the imaging element 9 and is orthogonal to the optical axis l of the imaging lens 4 at the midpoint in the width direction (the direction parallel to the pixel row of the imaging element 9). Thus, the slider 7 is held and moved by the slider 7. FIG. 3 shows the inspection target optical member 9 viewed from the position of the imaging lens 4.
It is a top view which shows the positional relationship of etc. In FIG. 3, the moving direction of the optical member 9 to be inspected by the slide table 7 is the left-right direction.

The optical member 9 to be inspected includes the imaging lens 4
Are arranged such that the surface thereof (the surface facing the imaging lens 4) is conjugate with the imaging surface of the imaging element 5. Therefore, the imaging device 5 can capture an image (for one line) of the surface of the inspection target optical member 9. FIG.
In, an imaging target area for one line that can be imaged by the imaging element 5 is indicated by a two-dot chain line.
The magnification of the imaging lens 4 (that is, the position of the imaging device 3 itself and the position of the imaging lens 4 with respect to the imaging element 5)
The surface of the inspection target optical member 9 is adjusted so that an image can be formed on the imaging surface of the imaging element 5 over the entire width (the width in the pixel row direction of the imaging element 9).

On the other hand, the illumination lamp 1 emits illumination light (white light).
Which is fixed to a frame (not shown) of the optical member inspection apparatus. The diffusion plate 2 disposed between the illumination lamp 1 and the optical member 9 to be inspected includes
As shown in FIG. 3, it has a rectangular shape wider than the optical member 9 to be inspected, and its surface is processed as a rough surface. Therefore, the diffuser plate 2 can receive the illumination light emitted from the illumination lamp 1 on the entire back surface thereof, and diffuse and transmit the illumination light. The diffusion plate 2 is fixed to a frame (not shown) of the optical member inspection device so that the center of the diffusion plate 2 is orthogonal to the optical axis l of the imaging lens 4 and its outer edge is parallel to the pixel row of the imaging device 9. Have been.

On the surface of the diffusion plate 2, a light-shielding plate 8 as a light-shielding means having a belt-like shape is provided. Direction) in a direction parallel to the direction. The center of the light shielding plate 8 coincides with the optical axis l of the imaging lens 4. The total length of the light shielding plate 8 in the longitudinal direction is longer than the width of the inspection target optical member 9 (the width in the pixel row direction of the imaging device 5). Then, as shown in FIG. 3, when viewed from the position of the imaging device 3, both ends of the light shielding plate 8 are
It protrudes outside the outer edge of the optical member 9 to be inspected. Further, as shown in FIG. 1, the width of the light shielding plate 8 is wider than the interval between the marginal rays m, m of the light incident on each pixel of the image sensor 5. Therefore, all the light from the direction that can enter each pixel of the image sensor 5 is blocked by the light shielding plate 8, and the background of the inspection target optical member 9 imaged by the image sensor 5 is always dark. That is, after the illumination lamp 1, the diffusion plate 2, and the light shielding plate 8 pass through the optical member 9 to be inspected and enter the imaging lens 4, the imaging device 5
Corresponds to an illuminating unit that illuminates a portion of the optical member 9 to be inspected through which the light passes from outside the optical path of the light incident on the optical member 9.

As shown in FIGS. 2 and 3, auxiliary lighting devices 10, 10 are attached to both sides of the light-shielding plate 8 in the longitudinal direction. The auxiliary lighting device 10 includes an optical fiber bundle 11 and the optical fiber bundle 1.
The divergence restricting frame 12 is attached to the exit end of the divergence control unit 1 and a collimator lens 13 attached to the exit end of the divergence restricting frame 12. This divergence control frame 12
Is a member that limits the spread of light diverging from the emission end of the optical fiber bundle 11 according to a predetermined numerical aperture only in a direction parallel to the longitudinal direction of the light shielding plate 8. The collimator lens 13 is a lens that ^converts light that has spread to a predetermined width (width of the optical member 9 to be inspected × 2 ^−1/2 ) in the divergence control frame 12 into parallel light. The optical axis of the collimator lens 13 intersects the optical axis 1 of the imaging lens 4 at 45 degrees at the intersection of the optical axis 1 of the imaging lens 4 and the optical member 9 to be inspected. Therefore, the light (auxiliary illumination light) emitted from each auxiliary illumination device 10 illuminates a portion of the surface of the inspection target optical member 9 which can be imaged by the imaging element 5 with uniform illuminance and angle over the entire area. Can be. <Principle of Optical Defect Detection> Next, the principle in which an optical defect of the inspection target optical member 9 is imaged by the imaging element 5 in the optical member inspection apparatus configured as described above will be described below.

Since the light receiving surface of the pixel array of the image sensor 5 can be regarded as a line having almost no width, the light that can enter the image pickup lens 4 and enter each pixel of the image sensor 5 within the plane of FIG. Is a light beam having a light ray along the optical axis l of the imaging lens 4 as a principal ray, and is only light passing between the marginal rays m, m shown in FIG. When the marginal rays m, m are traced in the opposite direction, they intersect at the surface of the optical member 9 to be inspected and then spread toward the diffusion plate 2. And
On the diffusion plate 2, the space between the marginal rays m, m is shielded by the light shielding plate 8. Therefore, as shown in FIG.
Assuming that there is no optical defect in the region to be imaged by the image sensor 5 in the optical member 9 to be inspected (a portion conjugate with the light receiving surface of the pixel array of the image sensor 5 and its vicinity in the optical axis direction). No light is incident on each of the five pixels. That is, the light n diffused from the side of the light shielding plate 8 on the surface of the diffusion plate 2 passes through the imaging target area in the inspection target optical member 9, but the marginal rays m, m
, Does not enter the imaging lens 4. Further, light diffused from a side portion of the light shielding plate 8 on the surface of the diffusion plate 2 and transmitted through a portion other than the imaging target region in the inspection target optical member 9 can enter the imaging lens 4. It does not converge on each pixel. for that reason,
The image data output from the image sensor 5 is a bright portion corresponding to the outer edge of the optical member 9 to be inspected (due to the diffused light on the side surface).
All areas are dark except for.

On the other hand, as shown in FIG. 3, when there is a flaw C and a dust D in the imaging target area on the surface of the optical member 9 to be inspected, as shown in FIG. When the light n diffused from the side portion of the plate 8 hits the scratches C and the dust D, the light n
And dust D. Since the diffused light n ′ diverges around the intersection of the marginal rays m, m, a part of the light is incident on each pixel of the image sensor 5 via the image pickup lens 4. Therefore, images of the flaw C and the dust D (images brighter than the surroundings) are formed on the imaging surface of the imaging element 5. In addition,
Similar diffusion occurs also at the outer edges A and B of the inspection target optical member 9, so that images of these outer edges A and B (images brighter than the surroundings) are formed on the imaging surface of the imaging element 5. FIG.
Is an image sensor 5 when an image is taken at the position shown in FIG.
5 is a graph showing a luminance distribution of image data output from the image data. FIG. 6 shows a state in which the electric charges accumulated in each pixel by one imaging are sequentially read out by self-scanning within a cycle of one scanning.

The scratches and cracks have directivity in the direction in which light is diffused. That is, light incident from a direction parallel to the direction of the scratch or crack is transmitted as it is without being diffused, and light incident from a direction perpendicular to the direction is diffused. Therefore, as shown in FIG. 7, when the scratches or cracks K are formed parallel to the longitudinal direction of the light shielding plate 8, the light n diffused from the side of the light shielding plate 8 on the surface of the diffusion plate 2. Scratch or crack K
, The diffusion occurs as described above, and a part of the diffusion enters the imaging lens 4, and an image of the flaw or crack K is captured by the imaging element 5. On the other hand, as shown in FIG.
Along the direction orthogonal to the longitudinal direction of the
Is formed, as shown in FIG. 9 which is a vertical cross section in a direction orthogonal to the longitudinal direction of the light shielding plate 8, light n diffused from a side portion of the light shielding plate 8 on the surface of the diffusion plate 2 is formed. Since the light is incident parallel to the flaw or crack K, the incident light n is transmitted without being diffused. Since the light n travels outside the marginal rays m, m, it does not enter the imaging lens 4. Therefore, the image of the scratch or the crack K is not captured by the image sensor 5.

In order to solve such a problem, in this embodiment, the auxiliary lighting devices 10, 10 are attached. This auxiliary lighting device 10 includes a light shielding plate 8
A portion of the surface of the inspection target optical member 9 which can be imaged by the image sensor 5 is illuminated from the side in the longitudinal direction of the optical member 9. Therefore, even when the flaw or crack K is formed along the direction orthogonal to the longitudinal direction of the light shielding plate 8 as shown in FIG. 10, the auxiliary lighting device 10 is orthogonal to the flaw or crack K. Illumination light can be emitted from any direction. As a result, as shown in FIG. 10, diffusion occurs at the flaw or crack K, a part of the diffused light enters the imaging lens 4, and an image of the flaw or crack K is captured by the image sensor 5. <Method of Determining Optical Defect> As described above, the image pickup device 5
(Charge accumulation and scanning) is performed every time the inspection target optical member 9 moves by a unit distance in synchronization with the movement of the inspection target optical member 9 by the slide table 7. Then, every time imaging (charge accumulation and scanning) is performed by the imaging element 5, image data as shown in FIG.
The data is input to the image processing device 6 and written to the image memory 6a. FIG. 11 shows the relationship between the light-shielding plate 8, the region to be imaged by the image sensor 5 (indicated by a two-dot chain line), the relative position of the optical member 9 to be inspected, and the image data written in the image memory 6a. As shown in FIG. 11, as the optical member 9 to be inspected passes through the region to be imaged by the image sensor 5 (indicated by a two-dot chain line) from the state of (a) to the state of (d), the image memory 6a Each row of the image sensor 5
The image data for each scan captured by the above is sequentially written from the top row.

In this embodiment, the image processing device 6
Indicates that after all imaging by the imaging element 5 is completed,
The pass / fail judgment is made based on the image data (FIG. 11D) corresponding to the entire surface of the inspection target optical member 9 stored in the image memory 6a. Specifically, the image processing device 6
The luminance of each pixel of the image data stored in the image memory 6a is compared with a predetermined threshold, and the value of a pixel brighter than the predetermined threshold is set to “1”, and the values of other pixels are set to “0”. Perform a binarization process. Then, if the total number of pixels having a value of “1” after the binarization processing exceeds a predetermined determination reference value, it is determined that the inspection target optical member 9 is defective. <Control Processing> Next, the contents of the control processing executed by the image processing device 6 to determine whether the optical member 9 to be inspected is a non-defective product or a defective product will be described with reference to the flowchart of FIG. . As a precondition for starting this control processing, the slider 7b of the slide table 7 is located at the rightmost end of the slide rail 7a shown in FIG. 1, and the inspection target optical member 9 is imaged as shown in FIG. Optical axis l of lens 4
At a position deviated from the

The control process shown in FIG. 12 is started when an unshown inspection start button connected to the image processing device 6 is pressed. In the first step S01 after the start, the image processing apparatus 6 starts outputting a drive signal to the drive motor 7e of the slide table 7, and starts moving the optical member 9 to be inspected at a constant speed.

In the next S02, the image processing device 6 inputs the image data for one scan output from the image pickup device 5,
Write to the image memory 6a. In the next S03, the image processing device 6 checks whether or not the image data corresponding to the entire inspection target optical member 9 has been synthesized in the image memory 6a by writing the image data in S02. If the image data corresponding to the entire inspection target optical member 9 has not been synthesized yet, the process returns to S02, and the image data output from the image sensor 5 by the new imaging is input.

On the other hand, when the image data corresponding to the whole optical member 9 to be inspected is synthesized, in step S04, the image processing device 6 causes the optical member 9 to be inspected written in the image memory 6a. A binarization process is performed on the image data corresponding to the whole. That is, the brightness of all pixels of the image data stored in the image memory 6a is compared with a predetermined threshold. Then, the value of a pixel whose luminance is higher than the predetermined threshold is replaced with “1”, and the value of a pixel whose luminance is lower than the predetermined threshold is replaced with “0”.

In the next S05, the image processing device 6 measures the total number of pixels (dots) having a value of "1" in the image memory 6a, and determines the number of pixels (dots) having a value of "1". It is checked whether it is larger than a predetermined judgment reference value. If the number of pixels (dots) having a value of “1” is larger than the predetermined determination reference value, in S06, it is determined that the inspection target optical member 9 is defective, and that fact is determined. External output (image display, audio output). On the other hand, when the number of pixels (dots) having the value of “1” is equal to or smaller than the predetermined determination reference value, in S07, the inspection target optical member 9 is determined to be non-defective, and To the outside (image display, audio output). After the above, the image processing device 6 ends the control processing.

Note that "1" is used instead of the determination in S05.
It may be determined whether the diameter of the region consisting of a set of pixels having the value of is equal to or more than a predetermined value,
The determination may be made based on whether or not the sum of the luminance values in the pre-binarization image corresponding to the region including the set of pixels having the value “1” is equal to or greater than a predetermined value. <Operation of Embodiment> According to the first embodiment configured as described above, light that can pass through the inspection target optical member 9 and enter the imaging lens 4 and can enter each pixel of the imaging element 5. Are shielded on the diffusion plate 2 by the light shielding plate 8 in advance. Therefore, if no optical defect occurs in the inspection target optical member 9 in the imaging target region of the imaging element 5, the image data captured by the imaging element 5 is entirely dark. On the other hand, when an optical defect has occurred in the inspection target optical member 9 in the region to be imaged by the image sensor 5, light incident into this region from the side of the light shielding plate 8 is diffused by the optical defect. Then, a part of the diffused light enters the imaging lens 4. As a result, the image data picked up by the image pickup device 5 has a bright image of an optical defect emphasized on a dark background.

In this embodiment, the image pickup device 5
Is a line sensor. Therefore, the resolution (the total number of pixels arranged in the pixel column direction) can be increased without making the entire image sensor 5 too large. Moreover, unlike the area sensor, even if the number of pixels is increased to increase the resolution, the width of the line sensor (the width in the direction orthogonal to the pixel row) does not change. Therefore,
The incident angle of light that enters the imaging target region of the inspection target optical member 9 through the side of the light shielding plate 8 can be reduced. As a result, even if the degree of diffusion is slight, the diffused light enters the imaging lens 4. That is, the detection sensitivity of the optical defect can be made higher than that of the area sensor.

Then, the number of pixels (dots) whose luminance is higher than a predetermined judgment reference value in the image data picked up by the image pickup device 5 is measured, and the measured number of pixels (dots) is determined to be a fixed judgment reference value. They are compared, and a determination as to whether the product is good or defective is made objectively according to the result of the comparison.

[0049]

[Second Embodiment] The second embodiment of the present invention is different from the first embodiment in that the image processing device 6 has no image memory 6a, and the control processing by the image processing device 6 is performed as shown in FIG.
Is performed according to the flowchart shown in FIG. The control processing according to the flowchart of FIG.
The binarization process and the determination process are directly performed on the image data for each line input from the image sensor 5.

The control process according to the flowchart of FIG. 13 is started when an unillustrated inspection start button connected to the image processing device 6 is pressed. In the first step S11 after the start, the image processing device 6 starts outputting a drive signal to the drive motor 7e of the slide table 7, and starts the uniform movement of the optical member 9 to be inspected.

Next, the image processing device 6 executes S12 to S1
The processing enters the loop processing of No. 6. In the first step S12 after entering the loop processing, the image processing device 6 inputs the image data for one scan output from the image sensor 5.

In the next step S13, the image processing device 6 executes the processing in the step S1.
A binarization process is performed on the image data for one scan input in step 2. That is, the luminance of the image data for one scan is compared with a predetermined threshold, a portion having a luminance higher than the predetermined threshold is set to a logical value “1”, and a portion having a luminance lower than the predetermined threshold is set to a logical value. By setting it to “0”, the image data is converted into a rectangular output.

In the next S14, the image processing device 6 sets the S1
3. Measure the width (length of the portion of the logical value "1") T of the rectangular output converted in step 3. In the next S15, the image processing device 6
Checks whether the width T measured in S14 is larger than a predetermined reference value. Then, when it is determined that the width T measured in S14 is equal to or smaller than the predetermined determination reference value, the image processing device 6 advances the processing to S16.

In step S16, the image processing device 6 checks whether the input of the image data corresponding to the entire inspection target optical member 9 has been completed. If the image data corresponding to the entire optical member to be inspected has not been input yet, the image processing device 6 returns the process to S12, and inputs the image data output from the image sensor 5 by the new imaging. I do.

As a result of repeating the above loop processing, S1
If the width T measured at 4 exceeds a predetermined criterion value, S
If it is determined in S15, the image processing device 6 determines in S18
In step (1), it is determined that the inspection target optical member 9 is defective, and that fact is externally output (image display, audio output). In this case, the input of the image data thereafter is terminated, and the control processing ends at this point.

On the other hand, if it is determined in S16 that the input of the image data corresponding to the entire inspection target optical member 9 has been completed without determining that the width T has exceeded the predetermined determination reference value, the image processing is performed. In S17, the device 6 determines that the inspection target optical member 9 is a non-defective product, and outputs the fact to the outside (image display, sound output). And then
This control processing ends.

The other constructions and operations of the second embodiment are the same as those of the first embodiment, and the description is omitted.

[0058]

Third Embodiment A third embodiment of the present invention shows a configuration example suitable for inspection of an optical member having a power centered on the optical axis, such as a circular lens. Such an optical member is not suitable for inspection by the configuration of the first embodiment. FIG. 33 shows a state where the concave lens 14a as such an optical member is mounted on the slide table 7 of the first embodiment and slid and viewed from the position of the imaging device 3. As shown in FIG. 33, when the concave lens 14a is moved from the right side to the left side in the drawing with respect to the light shielding plate 8, the appearance of the concave lens 14a and the light shielding plate 8 becomes as shown in FIGS. Changes as shown. Similarly, FIG. 34 shows a state where the convex lens 14b is mounted on the slide table 7 of the first embodiment and slid and viewed from the position of the imaging device 3. FIG. 34
As shown in (a), when the convex lens 14b is moved from the right side to the left side in the drawing with respect to the light shielding plate 8, the appearance of the convex lens 14b and the light shielding plate 8 becomes as shown in FIGS. Change. Thus, the inspection target optical members 14a, 1
When the optical axis of 4b is deviated from the center of the light-shielding plate 8, the position of the light-shielding plate 8 seen through the inspection target optical members 14a and 14b appears to be shifted from the actual position. As a result, even if there is no optical defect in the inspection target optical members 14a and 14b, light diverging from the side position of the light shielding plate 8 in the diffusion plate 2 enters the imaging lens 4 and is imaged by the imaging element 5. Image data becomes brighter. Therefore, a bright image of an optical defect is not emphasized much, and a portion that is not an optical defect may be determined to be an optical defect. Therefore, in the third embodiment, in order to always make the optical axis of the optical member 14 to be inspected coincide with the center of the light shielding plate, the optical member 14 to be inspected is rotated about the optical axis. <Configuration of Optical Member Inspection Apparatus> A schematic configuration of the third embodiment is shown in a partial cross-sectional side view of FIG. As shown in FIG. 14, the illumination lamp 1, the diffusion plate 20, and the imaging device 3 that constitute the optical member inspection device are arranged on the same optical axis l.

The configuration of the image pickup device 3 is the same as that of the first embodiment, and the description is omitted. The image processing device 21 is a processor that determines whether the inspection target optical member 14 is a non-defective product or a defective product, performs predetermined image processing on image data input from the imaging element 5,
The degree of the optical defect of the inspection target optical member 14 is quantified, and this numerical value is compared with a predetermined criterion value (allowable value) to determine whether the numerical value is within the criterion value or exceeds the criterion value. Do. That is, the image processing device 21
It corresponds to a digitizing means and a judging means. The image processing apparatus 21 performs the above-described determination processing, and synchronizes with input of image data from the image sensor 5,
A control signal for rotating the inspection target optical member 14 is output to the drive motor 18. This image processing device 21
A first image memory 21a and a second image memory 21b for storing image data when performing the above-described image processing are built therein.

A pinion gear 17 is mounted on the drive shaft of the drive motor 18.
Is an annular holder 1 around the optical axis l of the imaging lens 4
5 meshes with an annular gear 16 attached to the periphery. The annular holder 15 holds the peripheral edge of the inspection target optical member 14 which is a circular lens over the entire circumference. Therefore, as long as the center of the peripheral edge of the inspection target optical member 14 and the optical axis match, the optical axis of the inspection target optical member 14 is coaxial with the optical axis 1 of the imaging lens 4. When the above-described control signal is output from the image processing device 21, the drive motor 18 rotates according to the control signal. Then, the holder 15 is rotationally driven via the gears 17 and 16, and the inspection target optical member 14 held by the holder 15 is rotationally driven at a constant speed in a plane orthogonal to the optical axis l. That is, these drive motors 18, both gears 17, 16,
The holder 15 constitutes a rotation unit for rotating the inspection target optical member 14 about the optical axis 1 of the imaging lens 4. The rotation direction of the inspection target optical member 14 is the same as that in FIG.
As seen from the side of the imaging device 3, it is counterclockwise. FIG. 15 is a plan view of the inspection target optical member 14 and the like as viewed from the imaging device 3 side.

The inspection target optical member 14 is arranged such that the surface of the imaging lens 4 (the surface facing the imaging lens 4) is conjugate with the imaging surface of the imaging device 5. Therefore, the imaging device 5 can capture an image (for one line) of the surface of the inspection target optical member 14. FIG.
In 5, an imaging target area for one line that can be imaged by the imaging element 5 is indicated by a two-dot chain line. The magnification of the imaging lens 4 (that is, the position of the imaging device 3 itself and the position of the imaging lens 4 with respect to the imaging element 5)
Is adjusted so that the entire area in the diameter direction of the inspection target optical member 14 can be imaged on the imaging surface of the imaging element 5.

On the other hand, the illumination lamp 1 emits illumination light (white light).
Which is fixed to a frame (not shown) of the optical member inspection apparatus. Diffusion plate 20 arranged between illumination lamp 1 and optical member 14 to be inspected
Has a disk shape larger in diameter than the optical member 14 to be inspected, as shown in FIG. 15, and its surface is processed as a rough surface. Therefore, the diffuser plate 20 can receive the illumination light emitted from the illumination lamp 1 on the entire rear surface thereof, and diffuse and transmit the illumination light. Note that this diffusion plate 20
Is fixed to a frame (not shown) of the optical member inspection device so that its center is perpendicular to the optical axis l of the imaging lens 4.

On the surface of the diffusion plate 20, a light-shielding plate 19 as a light-shielding means having a belt-like shape is arranged so that its longitudinal direction is perpendicular to the direction of the pixel row of the image pickup device 5 (the optical axis l of the image pickup lens 4). (Constant direction). The center of the light shielding plate 19 coincides with the optical axis l of the imaging lens 4. The total length of the light shielding plate 19 in the longitudinal direction is longer than the diameter of the optical member 14 to be inspected.
Then, as shown in FIG. 15, when viewed from the position of the imaging device 3, both ends of the light shielding plate 19 protrude outside the outer edge of the inspection target optical member 14. Further, as shown in FIG. 16 which is a cross-sectional view of the optical member inspection device in a direction orthogonal to the direction of the pixel rows of the image sensor 5, the width of the light-shielding plate 19 It is wider than the interval between the light beams m and m. Therefore, all the light from the direction that can enter each pixel of the image sensor 5 is blocked by the light shielding plate 19, and the background of the inspection target optical member 14 imaged by the image sensor 5 is always dark.

As shown in FIGS. 14 and 15, auxiliary lighting devices 10 are mounted on both sides of the light-shielding plate 8 in the longitudinal direction, respectively. Since the configuration of the auxiliary lighting device 10 is the same as that of the first embodiment,
The description is omitted. <Principle of Optical Defect Detection> In the optical member inspection apparatus configured as described above, light that can enter the imaging lens 4 and enter each pixel of the imaging element 5 in the plane of FIG. 4 is a light beam having a light ray along the optical axis 1 as a principal ray and only light passing between the marginal rays m, m shown in FIG. When these marginal rays m, m are traced in the opposite direction, they intersect at the surface of the inspection target optical member 14 and then spread toward the diffusion plate 20. Then, on the diffusion plate 20, a space between the marginal rays m, m
9 interrupted. Therefore, as shown in FIG. 16, an optical image is formed in an area to be imaged by the image sensor 5 in the inspection target optical member 14 (a part conjugate with the light receiving surface of the pixel array of the image sensor 5 with respect to the imaging lens 4 and its vicinity in the optical axis direction). If there is no target defect, no light is incident on each pixel of the image sensor 5. That is, the light n diffused from the side of the light shielding plate 19 on the surface of the diffusion plate 20 passes through the imaging target area in the inspection target optical member 14 but passes outside the marginal rays m, m. Does not enter. Further, light diffused from a side portion of the light shielding plate 8 on the surface of the diffusion plate 2 and transmitted through a portion of the inspection target optical member 14 other than the imaging target region can enter the imaging lens 4. It does not converge on each pixel. For this reason, the image data output from the image sensor 5 is dark over the entire area except for a bright portion (due to diffused light on the side surface) corresponding to the outer edge of the inspection target optical member 14.

On the other hand, as shown in FIG. 15, the defect C
And dust D, as shown in FIG.
When the light n diffused from the side of the light shielding plate 19 on the surface of the light 0 hits the flaws C and the dust D, the light n is diffused by the flaws C and the dust D. Since the diffused light n ′ diverges around the intersection of the marginal rays m, m, a part of the light is incident on each pixel of the image sensor 5 via the image pickup lens 4. Therefore, images of the flaw C and the dust D (images brighter than the surroundings) are formed on the imaging surface of the imaging element 5. Since the same diffusion occurs in the outer circumferences A and B of the inspection target optical member 14, images of the outer circumferences A and B (images brighter than the surroundings) are formed on the imaging surface of the imaging element 5. FIG. 18 is a graph showing a luminance distribution of image data output from the image sensor 5 when an image is taken at the position shown in FIG. Note that FIG. 18 shows a state in which charges accumulated in each pixel by one image pickup are sequentially read out by self-scanning within one scanning cycle.

The flaws or cracks K formed in parallel with the short direction of the light shielding plate 19 are illuminated from the side in the longitudinal direction of the light shielding plate 19 by the auxiliary lighting devices 10 as shown in FIG. Is done. Therefore, the scratches or cracks K formed parallel to the short direction of the light shielding plate 8
Also, diffusion occurs due to the illumination light from the auxiliary lighting device 10, a part of the diffusion is made to enter the imaging lens 4, and an image of the flaw or crack K is captured by the imaging element 5. <Method of Determining Optical Defect> As described above, the image pickup device 5
(Charge accumulation and scanning) are performed every time the inspection target optical member 14 rotates by a unit angle in synchronization with the rotation of the inspection target optical member 14 by the drive motor 18. Each time an image is taken (charge accumulation and scanning) by the image sensor 5, image data as shown in FIG.
is written to a. 20 to 24 show the light shielding plate 19,
A region to be imaged by the image sensor 5 (indicated by a two-dot chain line),
7 shows a relationship between the relative position of the inspection target optical member 14 and the image data written in the first image memory 21a. Specifically, FIG. 20 shows an initial state (points on the outer edge of the inspection target optical member 14 imaged at this time are “A” and “B”, respectively), and FIG. 21 shows an initial state. 22 shows a state where the optical member 14 to be inspected is rotated 90 degrees counterclockwise from the initial state, and FIG. 23 shows a state where the optical member 14 to be inspected is in the initial state. Shows a state rotated 135 degrees counterclockwise from
FIG. 24 shows an end state in which the inspection target optical member 14 has been rotated 180 degrees counterclockwise from the initial state. As shown in each of these drawings, as the inspection target optical member 14 rotates,
In each row of the first image memory 21a, image data of each scan captured by the image sensor 5 is written in order from the first row.

The vertical axis of the image data written in the first image memory 21a at the time shown in FIG.
The rotation angle of the optical member 14 to be inspected with reference to the diameter connecting B is shown, and the horizontal axis represents the distance from the center (optical axis) O of the optical member 14 to be inspected in the diameter direction. That is, the coordinate system of the image data written in the first image memory 21a is a polar coordinate system. In this polar coordinate system, a defect closer to the center O of the inspection target optical member 14 has a larger area, and a defect closer to the outer edge has a smaller area. Therefore, it is not possible to objectively determine whether or not the inspection target optical member 14 is non-defective based on the image data itself written in the first image memory 21a. Therefore, the image processing apparatus 21 in the present embodiment converts the image data in the polar coordinate system written in the first image memory 21a into image data in the rectangular coordinate system, and writes the image data in the second image memory 21b.

FIG. 25 is a diagram showing a method of converting coordinates from such a polar coordinate system to a rectangular coordinate system. The local coordinate system defined on the surface of the optical member 14 to be inspected and the pixel row of the image sensor 5 are shown. It shows the relationship with the absolute coordinate system using the direction as a reference (vertical axis). In FIG. 25, the local coordinate system defined on the surface of the inspection target optical member 14 is:
The optical axis O of the inspection target optical member 14 is defined as the origin 0, and a line connecting the point A and the point B on the outer edge of the inspection target optical member 14 is represented by Y.
Axis. A line perpendicular to the Y axis and passing through the origin 0 is defined as X
Axis. Also, since the value of each point on the vertical axis of the absolute coordinate system corresponds to the order of scanning of each pixel of the image sensor 5, if the resolution (the number of pixels) of the image sensor 5 is n, 0 to n−
Takes a value of 1. Then, at the point of n / 2, the vertical axis of the absolute coordinate system intersects the origin 0 of the local coordinates.

When the optical member 14 to be inspected rotates, the local coordinate system rotates counterclockwise around the origin 0 with respect to the vertical axis of the absolute coordinate system. At this time, assuming that the number of times of imaging (the number of scans) from the start of imaging is k, and the angle at which the inspection target optical member 14 rotates during one period of imaging (one scan) is θ, m (m However, 0 ≦ m ≦ n / 2)
The polar coordinate of the pixel P in the local coordinate system is P
(N / 2−m, kθ), and m ′ (where n / 2 <m ′ ≦ n
-1) The polar coordinate of the pixel P ′ in the local coordinate system is P ′ (m′−n / 2, π + kθ). When these polar coordinates P and P ′ are represented by rectangular coordinates, P (Px, P
y), P '(P'x, P'y). Here, Px = (n / 2−m) sin kθ (1) Py = (n / 2−m) cos kθ (2) Px ′ = (m′−n / 2) sin (180 + kθ) = − (M′−n / 2) sin kθ (3) Py ′ = (m′−n / 2) cos (180 + kθ) = − (m′−n / 2) cos kθ (4) . Therefore, by using these equations (1) to (4), the polar coordinate system can be converted to the rectangular coordinate system.

Now, as shown in FIG. 26 (a), the number of pixels (resolution) n of the image sensor 5 is 2048, and the number of pixels becomes 20 during the half rotation (180 degrees) of the optical member 14 to be inspected.
Assume that 48 images are taken (that is, θ = 180/204).
8). In this case, the image processing device 21 applies the above equations (1) and (2) to the pixels in the 0th to 1024th columns in the first image memory 21a, and Applies the above equations (3) and (4).
However, as shown in FIG. 26B, the second image memory 21
Since the origin (0, 0) of b is located not at the center but at the upper left, correction must be made to shift the origin position. More specifically, since the number of pixels in the second image memory 21b is 2048 × 2048, the image processing device 21 calculates X
1024 must be uniformly added to the coordinate values, and a correction must be made to uniformly add 1024 after inverting the polarity of the Y coordinate value obtained by the above equations (2) and (4).

To summarize the above, the image processing apparatus 21
The k-th row in the first image memory 21a shown in FIG.
The following equations (1 ′) and (2 ′) are executed for the pixels in the m-th column (m = 0 to 1024). Px = 1024 + (1024-m) sin kθ (1 ′) Py = 1024- (1024-m) cos kθ (2 ′) Then, based on the obtained values of Px and Py, FIG.
Py line, Px in the second image memory 21b shown in FIG.
Identify the pixels in the column as converted pixels. Then, the data written to the pixels in the k-th row and the m-th column in the first image memory 21 a is
The data is transferred to the pixels in the Py row and Px column in b.

On the other hand, the image processing device 21 is configured as shown in FIG.
For the pixel at the k-th row and m'-th column (m '= 1024 to 2047) in the first image memory 21a shown in FIG.
The following equations (3 ′) and (4 ′) are executed. Px ′ = 1024− (m′−1024) sin kθ (3 ′) Py ′ = 1024 + (m′−1024) cos kθ (4 ′) Then, based on the obtained values of Px ′ and Py ′, FIG.
6 (b), the line Px ′ in the second image memory 21b,
The pixel in the Py ′ column is specified as a pixel after conversion. Then, the data written to the pixels in the k-th row and m-th column in the first image memory 21a is transferred to the pixels in the Px'-th row and Py 'column in the second image memory 21b.

After the completion of the transfer, the image data stored in the second image memory 21b is substantially equivalent to the image data obtained by imaging the optical member 14 to be inspected by the area sensor. Irrespective of the position, the area of the optical defect in the image data is directly proportional to the area of the actual optical defect. Therefore, the image processing device 21 makes a pass / fail determination based on the image data stored in the second image memory 21b. Specifically, the image processing device 21 compares the luminance of each pixel of the image data stored in the second image memory 21b with a predetermined threshold, and sets the value of a pixel brighter than the predetermined threshold to “1”. And set the value of other pixels to “0”
Is performed. Then, if the total number of pixels having a value of “1” after the binarization processing exceeds a predetermined determination reference value, it is determined that the inspection target optical member 14 is defective. <Control Processing> Next, the image processing apparatus 21 is used to determine whether the inspection target optical member 14 is a good product or a defective product.
Will be described with reference to the flowchart of FIG.

The control process shown in FIG. 27 starts when an inspection start button (not shown) connected to the image processing apparatus 21 is pressed. In the first step S21 after the start, the image processing apparatus 21 starts outputting a drive signal to the drive motor 18 and starts the rotation of the inspection target optical member 14 at a constant speed.

In the next step S22, the image processing device 21 inputs the image data for one scan output from the image pickup device 5, and writes it in the first image memory 21a. In the next step S23, the image processing apparatus 21 checks whether or not the image data in the polar coordinate system corresponding to the entire inspection target optical member 9 has been combined in the first image memory 21a by writing the image data in S22. If the image data in the polar coordinate system corresponding to the entire inspection target optical member 9 has not been synthesized yet, the process returns to S22, and the image data output from the image sensor 5 by the new imaging is input.

On the other hand, when the image data in the polar coordinate system corresponding to the whole optical member 9 to be inspected is synthesized, the image processing apparatus 21 writes the image data in the first image memory 21a in S24. The image data in the polar coordinate system is subjected to coordinate conversion using the above equations (1 ′) to (4 ′), and the image data converted to the rectangular coordinate system is written in the second image memory 21b.

In the next step S25, the image processing device 21 performs a binarization process on the image of the entire optical member 9 to be inspected in the rectangular coordinate system written in the second image memory 21b. That is, the brightness of all pixels of the image data stored in the second image memory 21b is compared with a predetermined threshold. Then, the value of a pixel whose luminance is higher than the predetermined threshold is replaced with “1”, and the value of a pixel whose luminance is lower than the predetermined threshold is replaced with “0”.

In the next step S26, the image processing device 21 measures the total number of pixels (dots) having a value of “1” in the second image memory 21b, and determines the number of pixels (dots) having a value of “1”. Check if the number is greater than a predetermined criterion value. If the number of pixels (dots) having a value of “1” is larger than the predetermined determination reference value, in S27, it is determined that the inspection target optical member 9 is defective, and that fact is determined. External output (image display,
Audio output). On the other hand, when the number of pixels (dots) having a value of “1” is equal to or smaller than the predetermined determination reference value, in S28, the inspection target optical member 9 is determined to be non-defective, and To the outside (image display, audio output). After the above, the image processing device 21 ends the control processing.

Note that "1" is used instead of the determination in S26.
It may be determined whether the diameter of the region consisting of a set of pixels having the value of is equal to or more than a predetermined value,
The determination may be made based on whether or not the sum of the luminance values in the pre-binarization image corresponding to the region including the set of pixels having the value “1” is equal to or greater than a predetermined value. <Operation of the Embodiment> According to the third embodiment configured as described above, light that can pass through the inspection target optical member 14 and enter the imaging lens 4 and can enter each pixel of the imaging element 5. The light shielding plate 19 is used in advance by the light shielding plate 19.
Blocked above zero. Therefore, if no optical defect occurs in the inspection target optical member 14 in the imaging target region of the imaging device 5, the image data captured by the imaging device 5 is entirely dark. On the other hand, the optical member 14 to be inspected is in a range in which the image
In the case where an optical defect has occurred, the light incident on this region from the side of the light shielding plate 19 is diffused by the optical defect, and a part of the diffused light enters the imaging lens 4. As a result, the image data picked up by the image pickup device 5 has a bright image of an optical defect emphasized on a dark background.

In this embodiment, a lens having a refractive power around the optical axis is used as the inspection target optical member 14, and the optical axis of the inspection target optical member 14 coincides with the optical axis 1 of the imaging lens 4. The inspection target optical member 14 is rotated about the optical axis. Accordingly, when viewed from the position of the imaging device 3, the position of the light-shielding plate 19 that can be seen through the inspection target optical member 14 is different from that of the inspection target optical member 14.
Does not change from a position centered on the optical axis of the optical member 14 to be inspected. Therefore, if there is no optical defect in the inspection target optical member 14, the image data picked up by the imaging element 5 is always dark, and if there is a defect in the inspection target optical member 14, the image data is picked up by the imaging element 5. Image data becomes brighter according to the degree of defect.

Then, the image data in the polar coordinate system captured by the image pickup device 5 is converted into image data in the rectangular coordinate system, and the pixels having a luminance higher than a predetermined determination reference value in the converted image data in the rectangular coordinate system ( The number of pixels (dots) is measured, and the measured number of pixels (dots) is compared with a predetermined criterion value. According to the comparison result, it is objectively determined whether the product is good or defective. is there. <Modification of Embodiment> The above-described detection of the optical defect portion by the diffused light is established even if the direction of the light incident on the imaging target area of the imaging element 5 on the surface of the inspection target optical member 14 is only one direction. I do. Therefore, instead of the above-described light shielding plate 19, a substantially semicircular light shielding plate 19a as shown in FIG. 28 may be used.

When the optical member 14 to be inspected contains a cylindrical component (anamorphic lens, cylindrical lens, etc.), the refractive power of the optical member 14 to be inspected changes depending on the circumferential direction. Therefore, when viewed from the position of the imaging device 3, the light-shielding plate 19 that is visible through the inspection target optical member 14 is distorted as shown in FIG. 29 or 30 as the inspection target optical member 14 rotates. . In such a case, even if such a distortion occurs, the light transmitted from the optical member 14 to be inspected and incident on the imaging lens 4 can be blocked from the optical axis side as shown in FIG. What is necessary is just to employ | adopt the shading board 19b of the shape which the width | variety gradually expanded toward the outer edge side. By employing the light shielding plate 19b having such a shape, the detection accuracy in the vicinity of the optical axis l is improved, and the possibility of erroneously recognizing a normal portion as a defective portion also in the vicinity of the periphery can be at least prevented. Also in this case, a substantially semicircular light shielding plate 19c shown in FIG. 32 may be used instead of the light shielding plate 19b.

[0083]

Embodiment 4 The fourth embodiment of the present invention differs from the third embodiment in that an image memory 21a,
21b, and the control processing by the image processing apparatus 21 is performed according to a flowchart shown in FIG. The control processing according to the flowchart of FIG. 35 is to directly execute the binarization processing and the determination processing on the image data of each line input from the image sensor 5.

The control processing according to the flowchart of FIG. 35 is started when an unillustrated inspection start button connected to the image processing apparatus 21 is pressed. In the first step S31 after the start, the image processing apparatus 21 starts outputting a drive signal to the drive motor 18 and starts the rotation of the inspection target optical member 14 at a constant speed.

Next, the image processing apparatus 21 executes S32 through S
The process enters a loop process of 36. In the first step S32 after entering this loop processing, the image processing device 21 inputs the image data for one scan output from the image sensor 5.

In the next S33, the image processing device 21
A binarization process is performed on the image data for one scan input at 32. That is, the luminance of the image data for one scan is compared with a predetermined threshold, a portion having a luminance higher than the predetermined threshold is set to a logical value “1”, and a portion having a luminance lower than the predetermined threshold is set to a logical value. By setting it to “0”, the image data is converted into a rectangular output.

In the next S34, the image processing device 21
At step 33, the width (length of the portion of the logical value "1") T of the rectangular output converted is measured. In the next S35, the image processing device 21 checks whether the width T measured in S34 is larger than a predetermined determination reference value. Then, when it is determined that the width T measured in S34 is equal to or smaller than the predetermined determination reference value, the image processing device 21 advances the processing to S36.

At S36, the image processing device 21 checks whether the input of the image data corresponding to the whole optical member 9 to be inspected is completed. If the image data corresponding to the entire inspection target optical member 9 has not been input yet, the image processing device 21 returns the processing to S32, and outputs the image data output from the image sensor 5 by the new imaging. input.

As a result of repeating the above loop processing, S3
If the width T measured at 4 exceeds a predetermined criterion value, S
If it is determined in S35, the image processing device 21 determines in S3
In step 8, it is determined that the inspection target optical member 9 is defective, and the fact is output to the outside (image display, sound output). In this case, the input of the image data thereafter is terminated, and the control processing ends at this point.

On the other hand, if it is determined in S36 that the image data corresponding to the whole optical member 9 to be inspected has been input without determining that the width T has exceeded the predetermined determination reference value, the image processing apparatus 21 determines in S37 that the optical member 9 to be inspected is a non-defective product, and outputs the fact to the outside (image display, sound output). Then, thereafter, the control process is terminated.

The other configurations and operations of the fourth embodiment are the same as those of the third embodiment, and therefore the description thereof will be omitted.

[0092]

[Fifth Embodiment] A fifth embodiment of the present invention shows a configuration example suitable for inspection of an optical member having power around the optical axis such as a circular lens. However, unlike the imaging device 5 according to the third embodiment in which the imaging device 5 captures the entire area in the diameter direction of the inspection target optical member 14 at one time, the imaging device 5 according to the fifth embodiment is different from the center of the inspection target optical member 14 in the outer edge. Only the region up to is imaged at a time. This is because, in order to facilitate illumination with uniform illuminance by reducing the area to be illuminated, to increase the resolution by imaging a narrower area using the image sensor 5 having the same number of pixels, and to use a polar coordinate system. This is to simplify the processing by making the same calculation formula applicable to all pixels of the image data. <Structure of Optical Member Inspection Apparatus> The schematic structure of the fifth embodiment is shown in a partial sectional side view of FIG. As shown in FIG. 36, the illumination lamp 1, the diffusion plate 20, and the imaging device 3 which constitute the optical member inspection device are arranged on the same optical axis l.

In the fifth embodiment, as shown in FIGS. 36 and 37, the optical axis of the optical member 14 to be inspected, that is, the center O of the optical member 14 to be inspected and the holder 15 is
It is offset parallel to the optical axis 1 of the imaging lens 4. Specifically, the optical axis l of the imaging lens 4 passes through a midpoint between the center O and the outer edge of the inspection target optical member 14. That is, the drive motor 18 according to the fifth embodiment,
The gears 17 and 16 and the holder 15 correspond to a rotation unit that rotates the inspection target optical member 14 about a rotation axis that is offset from the optical axis 1 of the imaging lens 4. The magnification of the imaging lens 4 (that is, the position of the imaging device 3 itself and the position of the imaging lens 4 with respect to the imaging element 5)
It is adjusted so that a region from the center O to the outer edge of the surface of the inspection target optical member 14 can be imaged on the imaging surface of the imaging element 5.

The image processing device 22 includes the optical member 1 to be inspected.
Reference numeral 4 denotes a processor for determining whether the optical member 14 is a non-defective product or a defective product. At the same time, the numerical value is compared with a predetermined reference value (permissible value), and it is determined whether the numerical value is within the reference value or exceeds the reference value. That is,
The image processing device 22 corresponds to a digitizing unit and a determining unit. The image processing device 22 also drives a control signal for rotating the inspection target optical member 14 in synchronization with input of image data from the imaging device 5 in accordance with the above-described determination process. Output to the motor 18. The image processing device 22 includes a first image memory 22a and a second image memory 22b for storing image data when performing the above-described image processing.

The other configuration of the fifth embodiment is the same as that of the third embodiment, and the description is omitted. <Principle of Optical Defect Detection> In the fifth embodiment, the principle of detecting an optical defect of an optical member to be inspected is the same as that of the third embodiment, and a description thereof will be omitted. <Method of Determining Optical Defect> The image pickup (charge accumulation and scanning) by the image pickup device 5 is synchronized with the rotation of the optical member 14 to be inspected by the drive motor 18 and synchronized with the optical member 14 to be inspected.
Is performed each time the unit rotates by a unit angle. Each time an image is taken (charge accumulation and scanning) by the image sensor 5,
Image data as shown in FIG. 38 is input to the image processing device 22 and written to the first image memory 22a. FIG.
9 to 43 show the light-shielding plate 19, the image-capturing target area (indicated by a two-dot chain line) by the image-capturing element 5, and the optical member 1 to be inspected.
4 shows the relationship between the relative position of No. 4 and the image data written in the first image memory 22a. Specifically, FIG. 39 shows an initial state (the inspection target optical member 1 imaged at this time).
The point on the outer edge of No. 4 is defined as “B”, and 180 ° from this point “B”.
FIG. 40 shows a state where the optical member 14 to be inspected is rotated 90 degrees counterclockwise from the initial state, and FIG. 41 shows a state where the optical member 14 to be inspected is FIG. 42 shows a state where the optical member 14 to be inspected is rotated 270 degrees counterclockwise from the initial state, and FIG. 43 shows a state where the optical member 14 to be inspected is rotated counterclockwise from the initial state. 360 counterclockwise from initial state
Indicates the end state rotated by degrees. As shown in these figures, as the inspection target optical member 14 rotates, image data for each scan captured by the image sensor 5 is written in each row of the first image memory 22a in order from the first row.

The vertical axis of the image data written in the first image memory 22a at the time shown in FIG. 43 (b) is the optical member to be inspected based on the radius connecting the center (optical axis) O and the point B. 14 indicates the rotation angle, and the horizontal axis indicates the distance from the center O of the inspection target optical member 14 in the radial direction. That is, the first
The coordinate system of the image data written in the image memory 22a is a polar coordinate system. In this polar coordinate system, a defect closer to the center O of the inspection target optical member 14 has a larger area, and a defect closer to the outer edge has a smaller area. Therefore, the first
It is not possible to objectively determine whether the inspection target optical member 14 is non-defective based on the image data itself written in the image memory 22a. Therefore, the image processing device 22 in the present embodiment converts the image data in the polar coordinate system written in the first image memory 22a into the image data in the rectangular coordinate system, and writes the image data in the second image memory 22b.

FIG. 44 is a diagram showing a coordinate conversion method from such a polar coordinate system to a rectangular coordinate system. The local coordinate system defined on the surface of the inspection target optical member 14 and the pixel row of the image sensor 5 are shown. It shows the relationship with the absolute coordinate system using the direction as a reference (vertical axis). In FIG. 44, the local coordinate system defined on the surface of the inspection target optical member 14 is:
The center O of the inspection target optical member 14 is defined as the origin 0, and the line connecting the points A and B on the surface of the inspection target optical member 14 is defined as the Y axis. Also, a line orthogonal to the Y axis and passing through the origin 0 is defined as the X axis. Also, since the value of each point on the vertical axis of the absolute coordinate system corresponds to the order of scanning of each pixel of the image sensor 5, if the resolution (number of pixels) of the image sensor 5 is n, 0 to n-1
Take the value of At the point 0, the vertical axis of the absolute coordinate system intersects with the origin 0 of the local coordinates.

When the optical member 14 to be inspected rotates, the local coordinate system rotates counterclockwise around the origin 0 with respect to the vertical axis of the absolute coordinate system. At this time, if the number of times of imaging (the number of scans) from the start of imaging is k, and the angle at which the inspection target optical member 14 rotates during one cycle of imaging (one scan) is θ, the mth The polar coordinate of the pixel P in the local coordinate system is P (m, kθ). Here, Px = m sin kθ (5) Py = m cos kθ (6) Therefore, by using these equations (5) and (6), the polar coordinate system can be converted to the rectangular coordinate system.

Now, as shown in FIG. 45A, the number of pixels (resolution) n of the image pickup device 5 is 2048, and the number of pixels is 81 during one rotation (360 degrees) of the optical member 14 to be inspected.
If imaging is performed 92 times, θ = 360/8192. However, as shown in FIG. 45 (b), the origin (0,0) of the second image memory 22b is not located at the center but at the upper left, so that a correction for shifting the origin position must be made. The number of pixels of the second image memory 22b is 40
Since the number is 96 × 4096, specifically, the image processing device 2
2 is a correction that uniformly adds 2048 to the X coordinate value obtained by the above equation (5), and uniformly adds 2048 after inverting the polarity of the Y coordinate value obtained by the above equation (6). Must be applied.

To summarize the above, the image processing device 22
The following equations (5 ′) and (6 ′) are executed for each pixel in the first image memory 22a shown in FIG. Px = 2048 + msinkθ (5 ′) Py = 2048−mcoskθ (6 ′) Then, based on the obtained values of Px and Py, FIG.
Py line, Px in the second image memory 22b shown in FIG.
Identify the pixels in the column as converted pixels. Then, the data written to the pixels in the k-th row and the m-th column of the first image memory 22a is transferred to the second image memory 22b.
The data is transferred to the pixel in the Py line and the Px column in the middle.

After the completion of the transfer, the image data stored in the second image memory 22b is substantially equivalent to the image data obtained by imaging the optical member 14 to be inspected by the area sensor. Irrespective of the position, the area of the optical defect in the image data is directly proportional to the area of the actual optical defect. Therefore, the image processing device 22 makes a pass / fail determination based on the image data stored in the second image memory 22b. Specifically, the image processing device 22 compares the luminance of each pixel of the image data stored in the second image memory 22b with a predetermined threshold, and sets the value of a pixel brighter than the predetermined threshold to “1”. And set the value of other pixels to “0”
Is performed. Then, if the total number of pixels having a value of “1” after the binarization processing exceeds a predetermined determination reference value, it is determined that the inspection target optical member 14 is defective. <Control Process> In the fifth embodiment, the control process executed by the image processing apparatus 21 to determine whether the inspection target optical member 14 is a non-defective product or a defective product is the same as the control process shown in FIG. Is performed according to the flowchart of FIG.
However, the expressions used for the coordinate conversion in S24 in this control process are the expressions (5 ′) and (6 ′) as described above. <Operation of Embodiment> According to the fifth embodiment configured as described above, the imaging target area on the surface of the inspection target optical member 14 is different from that of the third embodiment using the imaging element 5 having the same number of pixels. Since the total length of the optical defect is short, it is possible to further enlarge the image of the optical defect and to take an image. That is, when inspecting an optical member having a refractive power around the optical axis,
The resolution can be maximized. Further, since such a narrow area is an imaging target area, it is easy to illuminate the imaging target area with the same illuminance by the illumination lamp 1 and the diffusion plate 20. Therefore, the accuracy of optical defect detection is improved accordingly. Further, when the image data in the polar coordinate system stored in the first image memory 22a is subjected to the coordinate conversion to the rectangular coordinate system, the common equations (5 ′) and (6 ′) are executed for all the pixels. All that is required is that the processing can be simplified.

The other operation of the fifth embodiment is as follows.
Since the third embodiment is the same as the third embodiment, the description is omitted. <Modification of Embodiment> Detection of an optical defect portion in the fifth embodiment can be performed even if the direction of light incident on the area to be imaged by the imaging device 5 on the surface of the inspection target optical member 14 is only one direction. It is possible. Therefore, instead of the light shielding plate 19 described above, a substantially quadrant light shielding plate 19d as shown in FIG. 46 may be used. When the inspection target optical member 14 includes a cylindrical component (anamorphic lens, cylindrical lens, or the like), the refractive power of the inspection target optical member 14 varies depending on the circumferential direction. Therefore, when viewed from the position of the imaging device 3, the light-shielding plate 19 that can be seen through the optical member 14 to be inspected is moved as shown in FIG.
As shown in the figure. In such a case, as shown in FIG. 49, the optical member to be inspected can be blocked from passing through the optical member to be inspected 14 and entering the imaging lens 4 even if such distortion occurs. 14 center O
What is necessary is just to employ | adopt the light-shielding plate 19e of the shape which the width | variety gradually expanded from the side to the outer edge side. Light shield plate 19 having such a shape
If e is used, the detection accuracy near the center O of the optical member to be inspected is improved, and the possibility of erroneously recognizing a normal portion as a defective portion also near the outer edge can be prevented at least. Also in this case, instead of the light shielding plate 19e, FIG.
0 may be used.

Further, in the fifth embodiment, FIG.
The control processing by the image processing device 22 may be executed according to the flowchart shown in FIG.

[0104]

[Embodiment 6] The sixth embodiment of the present invention is directed to the third embodiment.
As compared with the embodiment, the embodiment is characterized in that two line lighting devices 21 and 21 are provided instead of the lighting lamp 1.

FIG. 51 is a partial cross-sectional side view showing a schematic configuration of an optical member inspection apparatus according to the sixth embodiment, and FIG. 52 is a view showing a traveling state of light viewed from the side in FIG. is there.

Each line illuminating device 21 has the same configuration as the auxiliary illuminating device 10 except that the characteristics of the lens are set so that the emitted illuminating light diverges. Then, as shown in FIGS. 51 and 52, each line lighting device 21 is located below the diffusion plate 20 (below in FIG. 52).
, The illumination light emitting end is disposed at a position symmetrical with respect to the optical axis l so that the longitudinal direction of the light emitting end is parallel to the longitudinal direction of the light shielding plate 19. More specifically, each line illumination device 21 has an illumination light emitting end inclined toward the optical axis l and faces the edge of the light shielding plate 19 in the longitudinal direction. Therefore, FIG.
As shown in (1), each line illumination device 21 individually illuminates the contact point of the diffusion plate 20 with the edge of the light-shielding plate 19 in the longitudinal direction and a region on the side thereof (shown by a dotted line E).

The other constructions and operations of the sixth embodiment are the same as those of the third embodiment, and the description is omitted.

[0108]

[Embodiment 7] The seventh embodiment of the present invention is the same as the sixth embodiment.
Compared to the embodiment, the diffusion plate 20 and the light shielding plate 19 are omitted, and each line illumination device 21 is arranged outside the marginal rays m, m of the light incident on each pixel of the image sensor 5. And

FIG. 54 is a view showing a light traveling state in the optical member inspection apparatus according to the seventh embodiment. As shown in FIG. 54, each line illumination device 21 outputs an image of a region to be imaged by the image sensor 5 on the inspection target optical member 14 from outside the marginal rays m, m of light incident on each pixel of the image sensor 5 ( It is arranged so as to face a region through which light incident on the image sensor 5 after being incident on the imaging lens 4). Therefore, as shown in FIG. 55, the imaging target area (illustrated by the dotted line E) of the optical element 14 to be inspected by the imaging element is indicated by each of the line illumination devices 21 and 21.
Will be illuminated.

With the above configuration, in this embodiment as well, as long as there is no optical defect in the inspection target optical member 14, imaging after the illumination light emitted from each line illumination device 21 passes through the inspection target optical member 14. It does not enter the lens 4. Therefore, the background of the image captured by the image sensor 5 is always dark. On the other hand, when there is an optical defect in the region to be imaged by the imaging device 5 in the inspection target optical member 14, the illumination light diffuses due to the optical defect, and a part of the diffused illumination light becomes part of the imaging lens 4. Is converged on the image sensor 5 after being incident on the optical element, an image of the optical defect (image brighter than the surroundings) is picked up by the image sensor 5.

The other configurations and operations of the seventh embodiment are the same as those of the third embodiment, and therefore, the description thereof will be omitted.

[0112]

According to the optical member inspection apparatus of the present invention configured as described above, it is possible to judge whether a non-defective product is acceptable or not according to an objective criterion. Therefore, the quality of products used as non-defective products can be stabilized, and
Waste such as discarding non-defective products due to erroneous determination can be prevented.

[Brief description of the drawings]

FIG. 1 is a front view showing a schematic configuration of an optical member inspection apparatus according to a first embodiment of the present invention.

FIG. 2 is a partial side view of the optical member inspection apparatus of FIG. 1;

FIG. 3 is a plan view of the inspection target optical member and the like in FIG. 1 viewed from a position of an imaging device.

FIG. 4 is a diagram showing a light traveling state when an optical member to be inspected has no optical defect;

FIG. 5 is a diagram showing a traveling state of light when the inspection target optical member has an optical defect.

FIG. 6 is a graph showing a luminance distribution of image data output from an image sensor when an optical member to be inspected has an optical defect;

FIG. 7 is a plan view showing a state in which a scratch or a crack is formed in parallel with the longitudinal direction of the light shielding plate.

FIG. 8 is a plan view showing a state in which a scratch or a crack is formed perpendicular to the longitudinal direction of the light shielding plate.

FIG. 9 is a longitudinal sectional view showing a state where illumination light is transmitted through the scratch or crack shown in FIG. 8;

FIG. 10 is a longitudinal sectional view showing a state in which illumination light from the auxiliary lighting device is diffused by a scratch or a crack shown in FIG. 8;

FIG. 11 is a diagram showing a relationship between relative positions of a light-shielding plate, an imaging target area, and an optical member to be inspected, and image data written in an image memory.

FIG. 12 is a flowchart showing the contents of control processing executed in the image processing apparatus of FIG. 1;

FIG. 13 is a flowchart showing the contents of control processing executed by the image processing apparatus according to the second embodiment of the present invention;

FIG. 14 is a side view showing a schematic configuration of an optical member inspection apparatus according to a third embodiment of the present invention.

FIG. 15 is a plan view of the inspection target optical member and the like in FIG. 14 viewed from the position of the imaging device.

FIG. 16 is a diagram showing a light traveling state when the inspection target optical member has no optical defect.

FIG. 17 is a diagram showing a light traveling state when an optical member to be inspected has an optical defect;

FIG. 18 is a graph showing a luminance distribution of image data output from an image sensor when an optical member to be inspected has an optical defect;

FIG. 19 is a longitudinal sectional view showing a state in which illumination light from the auxiliary illumination device is diffused by a flaw or a crack formed perpendicular to the longitudinal direction of the light shielding plate.

FIG. 20 is a diagram illustrating a relationship between relative positions of a light-shielding plate, an imaging target region, and an inspection target optical member and image data written in a first image memory.

FIG. 21 is a diagram showing a relationship between relative positions of a light-shielding plate, an imaging target area, and an inspection target optical member, and image data written in a first image memory.

FIG. 22 is a diagram showing a relationship between relative positions of a light shielding plate, an imaging target area, and an optical member to be inspected, and image data written in a first image memory.

FIG. 23 is a diagram showing a relationship between relative positions of a light-shielding plate, an imaging target area, and an optical member to be inspected, and image data written in a first image memory.

FIG. 24 is a diagram showing a relationship between relative positions of a light-shielding plate, an imaging target area, and an optical member to be inspected, and image data written in a first image memory.

FIG. 25 is a diagram showing a coordinate conversion method from a polar coordinate system to a rectangular coordinate system;

26 is a memory map showing image data stored in each image memory of FIG.

FIG. 27 is a flowchart showing the contents of control processing executed in the image processing apparatus of FIG. 14;

FIG. 28 is a plan view showing a modification of the light shielding plate.

FIG. 29 is a plan view showing a state in which the light shielding plate looks distorted;

FIG. 30 is a plan view showing a state in which the light shielding plate looks distorted;

FIG. 31 is a plan view showing a modification of the light shielding plate.

FIG. 32 is a plan view showing a modification of the light shielding plate.

FIG. 33 is an explanatory diagram of how a light shielding plate looks when a concave lens is inspected by the optical member inspection apparatus according to the first embodiment of the present invention.

FIG. 34 is an explanatory diagram of how a light shielding plate looks when a convex lens is inspected by the optical member inspection apparatus according to the first embodiment of the present invention.

FIG. 35 is a flowchart showing the contents of control processing executed by the image processing apparatus according to the fourth embodiment of the present invention.

FIG. 36 is a side view showing a schematic configuration of an optical member inspection apparatus according to a fifth embodiment of the present invention.

FIG. 37 is a plan view of the inspection target optical member and the like in FIG. 36 viewed from the position of the imaging device.

FIG. 38 is a graph showing a luminance distribution of image data output from an image sensor when an optical member to be inspected has an optical defect;

FIG. 39 is a diagram showing a relationship between relative positions of a light-shielding plate, an imaging target area, and an optical member to be inspected, and image data written in a first image memory.

FIG. 40 is a diagram showing a relationship between relative positions of a light-shielding plate, an imaging target area, and an optical member to be inspected, and image data written in a first image memory.

FIG. 41 is a diagram showing a relationship between relative positions of a light shielding plate, an imaging target area, and an inspection target optical member, and image data written in a first image memory.

FIG. 42 is a diagram showing a relationship between relative positions of a light shielding plate, an imaging target area, and an optical member to be inspected, and image data written in a first image memory.

FIG. 43 is a diagram showing a relationship between relative positions of a light shielding plate, an imaging target area, and an optical member to be inspected, and image data written in a first image memory.

FIG. 44 is a diagram showing a coordinate conversion method from a polar coordinate system to a rectangular coordinate system.

FIG. 45 is a memory map showing image data stored in each image memory of FIG. 36;

FIG. 46 is a plan view showing a modification of the light shielding plate.

FIG. 47 is a plan view showing a state in which the light shielding plate looks distorted;

FIG. 48 is a plan view showing a state in which the light shielding plate looks distorted;

FIG. 49 is a plan view showing a modification of the light shielding plate.

FIG. 50 is a plan view showing a modification of the light shielding plate.

FIG. 51 is a side view showing a schematic configuration of an optical member inspection apparatus according to a sixth embodiment of the present invention.

FIG. 52 is a view showing a light traveling state when the inspection target optical member has no optical defect.

FIG. 53 is a plan view of the diffusion plate and the light shielding plate of FIG. 51.

FIG. 54 is a front view showing the main part of the optical member inspection apparatus according to the seventh embodiment of the present invention;

FIG. 55 is a plan view of the optical member to be inspected in FIG. 54;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 illumination lamp 2 diffusion plate 3 imaging device 4 imaging lens 5 imaging device 6 image processing device 7 slide table 8 light shielding plate 9 inspection target optical member 10 auxiliary lighting device 14 inspection target optical member 15 holder 18 drive motor 19 light shielding plate 20 diffusion plate 21 image processing device 22 image processing device

Claims (14)

[Claims] An optical member inspection apparatus for detecting an optical defect of an optical member to be inspected, comprising: an imaging lens; an imaging element disposed at a position substantially conjugate with the optical member to be inspected with respect to the imaging lens; From outside the optical path of light that enters the imaging device after passing through the inspection target optical member and entering the imaging lens,
Illuminating means for illuminating a portion of the inspection target optical member through which the light is transmitted; digitizing means for quantifying a portion indicating an optical defect of the optical member in an image taken by the imaging device; An optical member inspection apparatus comprising: a determination unit configured to determine whether a numerical value digitized by the conversion unit exceeds a predetermined determination reference value. 2. A lighting device, comprising: a diffusing plate disposed at a position opposite to the imaging lens with respect to the inspection target optical member and diffusing illumination light toward the inspection target optical member; A light shielding means for blocking an optical path of light incident on the image pickup element after passing through a target optical member and entering the image pickup lens between the inspection target optical member and the diffusion plate. 2. The optical member inspection device according to 1. 3. The image sensor is a line sensor whose scanning direction extends in a certain direction orthogonal to the optical axis of the imaging lens, and the light shielding means has a spread in the certain direction. The optical member inspection device according to claim 2, wherein: 4. The optical member inspection apparatus according to claim 3, wherein a magnification of the photographing lens is adjusted so that an entire width of the inspection target optical member is imaged by the line sensor. 5. An optical member inspection apparatus according to claim 3, wherein said light shielding means has a band shape. 6. A moving means for moving the optical member to be inspected in a direction orthogonal to a scanning direction of the line sensor, wherein the line sensor captures an image of the optical member to be inspected at each position thereof, and The optical member inspection apparatus according to claim 4, wherein image data for each line is output. 7. The apparatus according to claim 3, further comprising an auxiliary lighting device for illuminating a part of the optical member to be imaged by the imaging means from a side of the light shielding means in the predetermined direction. Optical member inspection device. 8. The numerical value converting means reconstructs image data corresponding to the whole optical member to be inspected based on the image data for each line output from the line sensor, and includes the luminance in the image data. 7. The optical member inspection apparatus according to claim 6, wherein the number of pixels that exceeds a predetermined threshold value is measured. 9. The image forming apparatus according to claim 1, further comprising: a rotation unit configured to rotate the optical member to be inspected about an optical axis of the imaging lens. The optical member inspection apparatus according to claim 3, wherein the line sensor images the optical member to be inspected at each position and outputs image data for each line. . 10. The apparatus according to claim 1, further comprising a rotation unit configured to rotate the inspection target optical member around a rotation axis that is offset from an optical axis of the imaging lens. The region up to the outer edge is adjusted to be imaged by the line sensor, and the line sensor images the optical member to be inspected at each position and outputs image data for each line. The optical member inspection device according to claim 3. 11. A digital camera according to claim 11, wherein said digitizing means measures the length of a portion of the image data output from said line sensor for each line where the luminance exceeds a predetermined threshold. The optical member inspection device according to 6 or 10. 12. The digitizing means reconstructs image data of a polar coordinate system corresponding to the whole optical member to be inspected on the basis of image data of each line outputted from the line sensor. 11. The optical system according to claim 9, wherein the data is converted into image data in a rectangular coordinate system, and the number of pixels whose luminance exceeds a predetermined threshold in the image data in the rectangular coordinate system is measured. Member inspection device. 13. An optical member inspection apparatus according to claim 9, wherein said rotating means rotates the inspection target optical member about an optical axis of the inspection target optical member. 14. An optical member inspection apparatus according to claim 13, wherein said light shielding means has a band-like shape expanding from a portion intersecting the optical axis of said inspection target optical member toward an end. .