JP3360795B2 - Optical member inspection device - Google Patents

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, and some inspectors include defective products in the non-defective products, thereby deteriorating the quality of the entire product. 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.

SUMMARY OF THE INVENTION 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. That is,
The invention according to claim 1 is an optical member inspection device that detects an optical defect of an optical member to be inspected, comprising: an imaging lens;
An image rotator rotatably arranged around the optical axis of the imaging lens on the object side of the imaging lens, and an inspection target optical member on the optical axis opposite to the imaging lens with the image rotator interposed therebetween. A fixing member for fixing, a line sensor disposed at a position conjugate with the inspection target optical member fixed to the fixing member with respect to the imaging lens, and an inspection target optical member fixed to the fixing member On the side opposite to the image rotator, a diffusion plate that diffuses illumination light toward the inspection target optical member, and illumination light that passes through the inspection target optical member and enters the imaging lens after being incident on the imaging lens. A light blocking member that blocks the optical path between the diffusion plate and the inspection target optical member, and a first rotation that rotates the light blocking member about the optical axis. And rotating the image rotator so that the shadow of the light shielding member formed by the imaging lens always covers the line sensor in synchronization with the rotation of the light shielding member by the first rotation mechanism. A rotation mechanism, numerical value means for quantifying a portion indicating an optical defect of the optical member in an image picked up by the image sensor, and a numerical value quantified by the numerical value means a predetermined judgment reference value. Determining means for determining whether or not the time has been exceeded.

According to the optical member inspection apparatus thus configured, the light blocking member is oriented in a direction parallel to the direction of the line sensor in the initial state. Then, of the illumination light diffused from all parts of the diffusion plate, light that transmits through the optical member to be inspected, enters the imaging lens, and then travels in a direction that can enter the line sensor is transmitted by the light shielding member. And the optical member to be inspected. In this initial state, since the image rotator is also at the initial position, the shadow of the light shielding member covers the line sensor without being substantially rotated by the image rotator. However, if there is an optical defect in a linear region of the inspection target optical member that intersects the optical axis in parallel with the light shielding member, the illumination light that has entered the linear region through the side of the light shielding unit is subjected to the optical defect. Spread by defects. When a part of the diffused light enters the imaging lens, the diffused light converges on the line sensor, so that a bright image of the optical defect is captured by the line sensor. Therefore, a bright portion corresponding to an optical defect appears in an image captured by the line sensor. During this imaging, the light blocking member is
The first rotation mechanism rotates about the optical axis. Then, in synchronization with the rotation of the light blocking member, the second rotation mechanism rotates the image rotator. With this rotation, the image rotator rotates the shadow of the light blocking member to cover the line sensor. As a result, an optical defect existing in a linear region that intersects the optical axis in parallel with the light blocking member after rotation is imaged by the line sensor. Thus, when the light blocking means and the image rotator rotate, the linear region imaged by the line sensor rotates. Therefore, the whole area of the optical member to be inspected is imaged while the light shielding means is rotating.

The optical member inspection apparatus according to the present invention is suitable for inspecting an optical member having an optical axis such as a lens, but is capable of inspecting an optical member having no optical axis such as a prism or a plane parallel plate. You can also inspect. The optical defect of the optical member according to the present invention 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. Also,
Examples of defects inside the optical member include fluffs and cracks inside the optical member.

Since the light shielding means is for preventing light transmitted through the optical member to be inspected from directly entering the image pickup device, it can even shield the area surrounded by the marginal rays of the light beam entering the image pickup device. If so, it may be arranged anywhere between the diffusion plate and the optical member to be inspected. This light-shielding means may be a light-shielding pattern directly printed on the surface of the diffusion plate, a plate-shaped opaque member may be appropriately cut out and affixed to the diffusion plate, or may be a diffusion plate. The light shielding pattern may be printed on a separate transparent member surface.

[0010] The image rotator is an optical member that rotates the position of an outgoing light beam with respect to the position of an incident light beam around the optical axis by rotating about the optical axis of the imaging lens. This image rotator may rotate the position of the emitted light beam once while rotating itself, or may rotate the position of the emitted light beam one rotation while rotating itself half.

The diffusion plate may be a translucent member illuminated from behind or a reflective member illuminated from the front side. The first rotation mechanism may rotate only the light-shielding plate alone, or may rotate a diffusion plate to which the light-shielding plate 8 is attached.

In the case where the second rotation mechanism is to rotate the position of the outgoing light beam once while the image rotator makes one rotation, the image rotator is rotated at the same speed as the rotation speed of the light shielding plate by the first rotation mechanism. Rotate in the opposite direction. In the case where the second rotation mechanism rotates the position of the output light beam by one rotation while the image rotator makes a half rotation, the image rotator is rotated at half the rotation speed of the light shielding plate by the first rotation mechanism. Rotate in the opposite direction.

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 brightness, When there are a plurality of types of numerical values to be digitized by the digitizing unit, the determining unit may compare all of the numerical values with the determination reference value or a part of the types determined according to the type of the optical member. Only the numerical value of may be compared.

According to a second aspect of the present invention, the magnification of the photographic lens of the first aspect is adjusted so that the entire area of the inspection target optical member in the diameter direction intersecting the optical axis is imaged by the line sensor. That is what was specified.

According to a third aspect of the present invention, the light-shielding member of the first aspect has a band shape extending in a direction perpendicular to the optical axis. According to this configuration, the imaging target portion of the inspection target optical member is illuminated from both sides of the light shielding unit, so that the possibility that the illumination light diffused at the defect location enters the imaging lens is further increased.

According to a fourth aspect of the present invention, when the image rotator of the first aspect rotates a predetermined angle about the optical axis,
The position of the light beam emitted from the image rotator is specified by rotating about the optical axis by an angle twice the predetermined angle.

According to a fifth aspect of the present invention, the second rotating mechanism according to the fourth aspect rotates the image rotator at a half speed of the rotating speed of the light blocking member by the first rotating mechanism. It was done.

According to a sixth aspect of the present invention, the digitizing means of the first aspect determines the length of a portion of the image data for each line output from the line sensor where the luminance exceeds a predetermined threshold. It is specified by measuring.

According to a seventh aspect of the present invention, the digitizing means of the first aspect converts the image data of the polar coordinate system corresponding to the whole optical member to be inspected based on the image data of each line outputted from the line sensor. The image data of the polar coordinate system is converted into image data of the rectangular coordinate system, and the number of pixels whose luminance exceeds a predetermined threshold value in the image data of the rectangular coordinate system is measured. It was done.

According to an eighth aspect of the present invention, the light-shielding member of the third aspect has a band-like shape that expands from a portion intersecting the optical axis of the optical member to be inspected toward the end. Things. With this configuration, at the position near the optical axis of the optical member, the incident angle of the illumination light that hits 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.

According to a ninth aspect of the present invention, in the second aspect, a portion of the optical member to be inspected, which is rotated about the optical axis together with the light blocking member by a first rotating mechanism, is picked up by the image pickup means. By further comprising an auxiliary lighting device for lighting from near the end of the light shielding member,
It is specified. 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 and incident on the imaging lens.

The invention according to claim 10 is the first or fifth invention.
The second rotation mechanism rotates the image rotator in a direction opposite to the rotation direction of the light blocking member by the first rotation mechanism.

[0023]

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

[0024]

First Embodiment <Configuration of Optical Member Inspection Apparatus> The schematic configuration of an optical member inspection apparatus according to the first embodiment is shown in a front sectional view of FIG.
As shown in FIG. 1, the illumination unit L, the test object holder 23, the image rotator 14, 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 (CCD line sensor) for picking up an image formed by light converged by the image pickup lens 4. In FIG. 1, the image sensor 5 includes
It is installed so that the pixel column is directed in the left-right direction. Further, the pixel row of the image sensor 5 has
It intersects perpendicularly with the optical axis l of the imaging lens 4. Note that the imaging lens 4 is capable of moving forward and backward (adjusting the focus) with respect to the image pickup device 5 in the image pickup device 3, and the image pickup device 3 itself is also provided with an optical member inspection device such that it can move forward and backward in the optical axis l direction. It is attached to a frame (not shown).

The image pickup device 5 picks up an image in a line at predetermined time intervals (a time period in which electric charges are appropriately accumulated in each pixel), and scans each pixel in the order in which the pixels are arranged, and accumulates the image in each pixel. Output charge. 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 defective product, and performs predetermined image processing on image data input from the imaging device 3. The numerical value of the degree of optical defect of the optical member 9 to be inspected is quantified, and this numerical value is compared with a predetermined criterion value (allowable value) to determine whether this 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 device 6 has a first image memory 6a for storing image data when performing the image processing.
And a second image memory 6b. Further, the image processing device 6 performs the above-described determination process, and in synchronization with the input of image data from the imaging device 3,
A control signal for rotating the image rotator 14 and the diffusion plate 2 is output to the motor drive circuit 7.

On the other hand, as shown in FIG. 2A which is a side view and FIG. 2B which is a plan view, the image rotator 14 arranged on the object side of the imaging lens 4 has a rectangular lower surface 14a, It is a trapezoidal prism having a short side of the lower surface 14a and a square upper surface 14e having four sides of the same length. The image rotator 14 has an upper surface 14 e and a lower surface 14 a by an image rotator holder 15.
Are mounted on a frame (not shown) of the optical member inspection apparatus so as to be rotatable about an optical axis 1 of the imaging lens 4 orthogonal to each center of the imaging lens 4.

The image rotator 14 has a lower surface 14
The two triangular prisms are formed by an interface 14b that connects one short side of a with the side on the upper surface 14e parallel to the short side and on the opposite side of the optical axis 1 and intersects the optical axis 1 at 45 °. Is divided into The interface 14b is provided with a coating that transmits incident light near the incident angle of 0 ° and reflects incident light near the incident angle of 45 °. A similar coating is applied to the lower surface 14a. Also,
Side surface 1 connecting each short side of lower surface 14a and the shorter side of upper surface 14e
4c and 14d are provided with an internal reflection coating.

Due to such a configuration, the light incident on the image rotator 14 from the lower surface 14a in parallel with the optical axis l includes the incident point of the light on the lower surface 14a and is transmitted to the longer side of the lower surface 14a and the optical axis l. On the other hand, they travel in parallel sections. Specifically, the light is reflected 90 degrees at the interface 14b and proceeds to the side, is reflected at the side surface 14c toward the lower surface 14a, is reflected at the lower surface 14a toward the interface 14b, and moves the interface 14b near 0 degree. Transmit at the angle of incidence, side 14
At d, the light is reflected toward the interface 14b.
The light enters at an incident angle near the angle, is reflected toward the upper surface 14e, and exits vertically from the upper surface 14e. At this time, when the image rotator 14 is viewed from above (the imaging lens 4 side),
The position of the incident light and the position of the emitted light are line-symmetric with respect to a line Q passing through the center of the image rotator 14 (the centers of the lower surface 14a and the upper surface 14e) in parallel with the short side of the lower surface 14a. Therefore, as shown in FIGS. 2A to 2C, light from the point B on the optical axis 1 of the imaging lens 4 passes through the image rotator 14 regardless of the rotational position of the image rotator 14. Go to a point B 'on the optical axis l. Further, as shown in FIGS. 2A and 2B, a point shifted in a direction parallel to the long side of the lower surface 14a with respect to the optical axis l (the center of the image rotator 14 is parallel to the long side of the lower surface 14a). The light from the passing line R (point A) passes through the image rotator 14 and then proceeds to a point A ′ symmetrical with respect to the optical axis 1 when viewed from above (the imaging lens 4 side). Also, as shown in FIG.
The other light from the point A passes through the image rotator 14 and then proceeds to a point A ″ that is line-symmetric with respect to the line Q when viewed from above (the imaging lens 4 side). As a result, the line segment AB Is
When viewed from above (the imaging lens 4 side), the line Q and the line segment AB
When the image rotator 14 is at a rotational position where the image rotator is orthogonal to the image rotator, the image rotator 14 can be seen at the position A′-B ′ shown in FIG. When the image rotator 14 is rotated by half a rotation around the optical axis l, an image seen through the image rotator 14 is obtained. One revolution in the same direction.

The image rotator holder 15 described above
The image rotator 14 has a cylindrical outer peripheral surface centered on the optical axis 1 and is fitted to the lower surface 14 a side peripheral edge of the image rotator 14.
An annular gear 16 is integrally formed on the outer peripheral surface of the image rotator holder 15.
Is the image rotator drive motor (pulse motor) 1
8 meshes with a pinion gear 17 attached to the drive shaft. Therefore, this image rotator drive motor 1
8 rotates its drive shaft, the image rotator 1
4 is rotationally driven via both gears 17 and 16. That is, the image rotator holder 15, the two gears 16, 17 and the image rotator drive motor 18
However, a second rotation mechanism that rotates the image rotator 14 so that the shadow of the light shielding plate 8 formed by the imaging lens 4 always covers the imaging element 5 is configured.

The optical member 9 to be inspected is, as shown in FIG. 1 and FIG.
It is a concave lens that has been centered. The optical member 9 to be inspected is connected to the optical axis 1 on the opposite side of the image rotator 14 from the imaging lens 4 by an object holder 23 as a fixing member fixed to a frame (not shown) of the optical member inspection apparatus. It is held so as to be coaxial. Note that, on the optical axis l, the surface of the optical member 9 to be inspected (the surface facing the image rotator 14) is the image rotator 1
4, the imaging lens 4 is located at a position conjugate with the imaging surface of the imaging element 5 with respect to the imaging lens 4. Therefore, the imaging device 5 can capture an image (for one line) of the surface of the inspection target optical member 9. In FIG. 3, an imaging target area for one line that can be imaged by the imaging element 5 is indicated by a two-dot chain line. Note that 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 such that the entire area in the diameter direction of the inspection target optical member 9 is imaged on the imaging surface of the imaging element 5. It has been tuned to be able to.

Also, when the line Q of the image rotator 14 is oriented in a direction perpendicular to the plane of FIG. 1 (hereinafter, the position of the image rotator 14 at this time is referred to as the “initial position”) by the function of the image rotator 14 described above. 1), an image of the inspection target optical member 9 on the diameter in the left-right direction of FIG. When the image rotator 14 is rotated 45 degrees counterclockwise as viewed from the imaging device 3 side in this state, the image of the inspection target optical member 9 having a diameter oriented in a direction perpendicular to the plane of FIG. The image is captured by the element 5. From this state, the image rotator 14 further moves
When the optical member 9 is rotated five degrees,
An image having a diameter in the left-right direction of FIG.

The illumination unit L is provided with an optical axis l of the imaging lens 4.
The diffusion plate 2 and the illumination lamp 1 arranged in this order from the side closer to the inspection target optical member 9, and the band-shaped light shielding plate 8 attached to the surface of the diffusion plate 2 (the surface on the inspection target optical member 9 side). A diffusion plate holder 19 that holds the diffusion plate 19 and rotates about the optical axis l; and a pair of auxiliary lighting devices 10 and 10 that are respectively installed on both sides of the light shielding plate 8 on the diffusion plate holder 19. , Etc.

The illumination lamp 1 is an incandescent lamp that emits illumination light (white light), and is fixed to a frame (not shown) of the optical member inspection device. The diffuser plate holder 19 surrounding the illumination lamp 1 has a cylindrical portion 19a coaxial with the optical axis l of the imaging lens 4 and a circumferential direction from an end opening of the cylindrical portion 19a (an opening on a side away from the optical member 9 to be inspected). And an annular flange portion 19b coaxially expanding. The diffusion plate holder 19 is mounted on a frame (not shown) of the optical member inspection device so as to be rotatable about the optical axis l of the imaging lens 4.

The disk-shaped diffusion plate 2 having a diameter larger than that of the optical member 9 to be inspected is fitted into the opening at the end of the cylindrical portion 19a of the diffusion plate holder 19 (the opening on the side closer to the optical member 9 to be inspected). ing. Accordingly, the diffusion plate 2 is located on the opposite side of the image rotator 14 with the inspection target optical member 9 interposed therebetween, and is coaxial with the optical axis 1 of the imaging lens 4 via the diffusion plate holder 19 and is connected to the optical axis l. Rotate as center. Since the surface of the diffusion plate 2 (the surface on the side of the inspection target optical member 9) is processed as a rough surface, the diffusion plate 2
Illuminating light emitted from the optical member 9 can be received on the entire back surface and diffused toward the optical member 9 to be inspected.

As shown in FIG. 3, the light-shielding plate 8 as a light-shielding member adhered on the surface of the diffusion plate 2 has its center aligned with the optical axis l of the imaging lens 4. The longitudinal direction is directed to the diameter direction of the diffusion plate 2. In addition,
The total length of the light shielding plate 8 in the longitudinal direction is longer than the diameter of the optical member 9 to be inspected. The width of the light-shielding plate 8 is shown in FIG. 6 which is a side cross-sectional view as viewed from the end of the image sensor 5 while developing the optical path in the image rotator 14 at the initial position to linearize the optical axis l. Thus, the distance between the marginal rays m, m of the light incident on each pixel of the image sensor 5 is wider. Further, as shown in FIG. 1, the light-shielding plate 8 is initially set so that the longitudinal direction is in a direction parallel to the pixel rows of the image sensor 5 when the image rotator 14 is at the initial position.

The auxiliary illuminators 10 and 10 are provided on the surface of the flange portion 19b of the diffusion plate holder 19 (the optical member 9 to be inspected).
On both sides of the light shielding plate 8 (light shielding plate 8).
(On the extension line in the longitudinal direction). Each auxiliary lighting device 10 has a flange 19b.
A light box 25 fixed thereon, an auxiliary illumination lamp 26 built in the light box 25, an optical fiber bundle 11 for guiding auxiliary illumination light emitted from the auxiliary illumination lamp 26 to the outside of the light box 25, and an optical fiber Divergence restricting frame 1 attached to the output end of bundle 11 and fixed above light box 25 by stay 24
2 and a collimator lens 13 attached to the emission end of the divergence restricting frame 12. The divergence control frame 12 is a member that limits the spread of light diverging from the exit 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. Also,
The collimator lens 13 is a lens that ^converts light spread to a predetermined width (width of the gloss 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 is transmitted to the inspection target optical member 9.
Can be illuminated with a uniform illuminance and angle over the entire area of the surface of the device that can be imaged by the image sensor 5.

Each lead wire for passing a current to each of the auxiliary lighting lamps 26, 26 passes through the flange portion 19b of the diffusion plate holder 19, and the back surface of the flange portion 19b (the optical member 9 to be inspected). On the opposite side), one of the two annular electrodes 27a and 27b concentrically laid (see FIG. 4 which is a bottom view of the diffusion plate holder 19 from the lower side in FIG. 1) is connected. I have. These annular electrodes 27a,
As shown in FIG. 5 which is a partial longitudinal sectional view taken along line VV in FIG. 1, 27b is implanted in a sliding brush holding portion 28 fixed to a frame (not shown) of the optical member inspection device. It is always in sliding contact with either one of the two sliding brushes 28a, 28b. Therefore, each of these sliding brushes 28a,
When the electric wires 29, 29, which are respectively connected to the electric wires 28b, are connected to a power source (not shown), current flows through the auxiliary lighting lamps through sliding contacts between the sliding brushes 28a, 28b and the annular electrodes 27a, 27b. 26, 26. Therefore, regardless of the rotational position of the diffuser plate holder 19, the auxiliary illumination light is always emitted from the auxiliary illumination devices 10 and 10 and radiated toward the inspection target optical member 9 from outside the both ends of the light shielding plate 8. is there.

An annular rim 23 is fitted around the flange 19b of the diffusion plate holder 19. An annular gear 20 is integrally formed on the outer peripheral surface of the rim 23. The annular gear 20 is a pinion gear 21 attached to a drive shaft of a light shielding plate drive motor (pulse motor) 22.
Is engaged. Therefore, when the light shielding plate drive motor 22 rotates its drive shaft, the diffusion plate 2, the light shielding plate 8, and the auxiliary lighting devices 10, 10 are rotationally driven via both gears 20, 21. That is, the diffusion plate 2, the diffusion plate holder 19, the rim 23, the two gears 20, 21 and the light shielding plate driving motor 22 constitute a first rotation mechanism for rotating the light shielding plate 8 about the optical axis l. I have.

When the motor drive circuit 7 receives a control signal from the image processing device 6 as a part of the first rotation mechanism and the second rotation mechanism, the motor drive circuit 7 views the diffusion plate 2 and the light shielding plate 8 from the side of the imaging device 3. A drive pulse for rotating clockwise at a first rotational speed at a constant rotational speed is supplied to the light shielding plate drive motor 22, and the image rotator 14 is rotated at a first rotational speed of 1 at a counterclockwise direction when viewed from the imaging device 3 side. A drive pulse for rotating at a constant speed at a second rotation speed of / 2 is supplied to the image rotator drive motor 18. <Principle of Optical Defect Detection> In the optical member inspection apparatus configured as described above, in the plane of FIG.
Is incident on each pixel of the image sensor 5 and is a light beam whose main ray is a light ray along the optical axis l of the imaging lens 4 and passes between the marginal rays m, m shown in FIG. Only light. 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. Then, 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. 6, an optical image is formed in an area to be imaged by the image sensor 5 in the inspection target optical member 9 (a part conjugate with the light receiving surface of the pixel array of the image sensor 5 with respect to the image pickup lens 4 and its vicinity in the optical axis direction). Assuming that 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 8 on the surface of the diffusion plate 2 passes through the imaging target region in the inspection target optical member 9, 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 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. Therefore, the image data output from the imaging device 3 is dark over the entire region except for a bright portion (due to diffused light on the side surface) corresponding to the outer edge of the inspection target optical member 9.

On the other hand, as shown in FIG. 3, when the flaw C and the dust D are present 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 the pixels of the image sensor 5 via the image rotator 14 and 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, the outer circumference A of the optical member 9 to be inspected,
Also in B, similar diffusion occurs, so that the 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. 8 is a graph showing a luminance distribution of image data output from the imaging device 3 when imaging is performed at the position shown in FIG. Note that FIG. 8 shows a state in which the 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 without diffusion, and light incident from a direction perpendicular to the direction is diffused. Therefore, as shown in FIG. 9, when the flaw or crack K is formed in parallel with 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 light shielding plate 2. Scratch or crack K
, The diffused light is generated as described above, and a part of the diffused light is incident on the imaging lens 4, and an image of the flaw or crack K is captured by the image sensor 5. . On the other hand, as shown in FIG. 10, when the scratch or crack K is formed along the direction orthogonal to the longitudinal direction of the light shielding plate 8, the longitudinal section in the direction orthogonal to the longitudinal direction of the light shielding plate 8 is formed. As shown in FIG. 11, which is a surface, the light n diffused from the side of the light-shielding plate 8 on the surface of the light-shielding plate 2 is incident parallel to the scratches or cracks K.
The incident light n is transmitted without being diffused.
And since this 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 the present 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 imaging element 5 is illuminated from outside the end in the longitudinal direction of the optical member 9. Therefore, even if the scratches or cracks K are formed along the direction perpendicular to the longitudinal direction of the light shielding plate 8 as shown in FIG.
As shown in FIG. 2, illumination light can be emitted from a direction orthogonal to the scratch or crack K. As a result, diffused light is generated at the flaw or crack K, a part of the diffused light is incident on the photographing lens 4, and an image of the flaw or crack K is captured by the image sensor 5. <Optical Defect Determination Method> As described above, the light shielding plate 8
Are initially set such that when the image rotator 14 is at the initial position, its longitudinal direction is oriented in a direction parallel to the pixel rows of the image sensor 5. The diffusion plate 2 and the light shielding plate 8 are
The image rotator 14 rotates at a constant speed in the clockwise direction at a first rotation speed when viewed from the imaging device 3 side, and the image rotator 14 is a second rotation which is １ ／ of the first rotation speed in a counterclockwise direction when viewed from the imaging device 3 side. It rotates at the rotation speed of. Therefore, when viewed from the imaging device 3 side, the function of the image rotator 14 described above allows the light-shielding plate 8 to appear to be stopped in a state where the longitudinal direction thereof is oriented in the direction of the pixel row of the imaging element 5, and the optical member to be inspected. 9 appears to rotate counterclockwise at the first rotation speed. Therefore, as long as the optical member 9 to be inspected has no optical defect, the shadow of the light-shielding plate 8 always covers the image sensor 5, and a region to be imaged by the image sensor 5 in the optical member 9 to be inspected (on the pixel column of the image sensor 5). The imaged diametrical region) rotates clockwise relative to the optical member 9 to be inspected.

The image pickup (charge accumulation and scanning) by the image pickup device 5 is synchronized with the rotation of the diffusion plate 2 and the light shielding plate 8 and the optical member 9 to be inspected by the respective drive motors 18 and 22, and the inspection seen from the image pickup device 3 side. This is performed each time the target optical member 9 relatively rotates by a unit angle. Then, every time imaging (charge accumulation and scanning) is performed by the imaging element 5, image data as shown in FIG. 8 is input to the image processing device 6 and written to the first image memory 6a. 13 to 17
Indicates the relative positions of the light shielding plate 8, the imaging target area (indicated by a two-dot chain line), and the inspection target optical member 9, and the first image memory 6a.
Shows the relationship with the written image data. Specifically, FIG. 13 shows a state in which the image rotator 14 is at the initial position (initial state) (points on the outer edge of the inspection target optical member 9 imaged at this time are denoted by “A” and “B”, respectively). FIG. 14 shows a state in which the inspection target optical member 9 viewed from the imaging device 3 side is relatively rotated counterclockwise by 45 degrees from the initial state, and FIG. FIG. 16 shows a state in which the target optical member 9 is rotated by 90 degrees in the counterclockwise direction from the initial state, and FIG. FIG. 17 shows the state rotated by degrees.
This shows an end state in which the inspection target optical member 9 viewed from the imaging device 3 is relatively rotated counterclockwise by 180 degrees from the initial state. As shown in each of these drawings, as the inspection target optical member 9 viewed from the imaging device 3 relatively rotates, the first
In each row of the image memory 6a, image data for 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 6a at the time shown in FIG.
The relative rotation angle of the optical member 9 to be inspected with reference to the diameter connecting between the optical members 9 is shown, and the horizontal axis represents the distance in the diameter direction from the center (optical axis) O of the optical member 9 to be inspected. That is, the coordinate system of the image data written in the first image memory 6a is a polar coordinate system. In the polar coordinate system, a defect nearer the center O of the inspection target optical member 9 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 9 is non-defective based on the image data itself written in the first image memory 6a. Therefore, the image processing device 6 in the present embodiment converts the image data in the polar coordinate system written in the first image memory 6a into image data in the rectangular coordinate system, and writes the image data in the second image memory 6b.

FIG. 18 is a view showing such a coordinate conversion method from the polar coordinate system to the rectangular coordinate system. The local coordinate system defined on the surface of the inspection target optical member 9 seen from the imaging device 3 side, and It shows a mutual relationship of an absolute coordinate system with the direction of the pixel row of the image sensor 5 as a reference (vertical axis). In FIG. 18, the local coordinate system defined on the surface of the inspection target optical member 9 seen from the imaging device 3 side is such that the optical axis O of the inspection target optical member 9 is the origin 0 and the inspection target optical member 9
A line connecting point A and point B on the outer edge is defined as a Y axis. A line passing through the origin O perpendicular to the Y axis is defined as the X axis. Further, 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-1 Take a value. 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 inspection target optical member 9 seen from the imaging device 3 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 9 rotates during one cycle (one scan) of imaging is θ,
The polar coordinate in the local coordinate system of the m-th (where 0 ≦ m ≦ n / 2) pixel P in the image sensor 5 is P (n / 2−m, kθ).
And the polar coordinate of the m ′ (where n / 2 <m ′ ≦ n−1) pixel P ′ in the local coordinate system is P ′ (m′−n /
2,180 + kθ). When these polar coordinates P and P ′ are represented by rectangular coordinates, P (Px, py) and 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. 19A, the number of pixels (resolution) n of the image pickup device 5 is 2048, and the image pickup is performed 2048 times while the optical member 9 to be inspected makes a half turn (180 degrees). (Ie, θ = 180/2048). In this case, the image processing device 6 sets 0 to 0 in the first image memory 6a.
The above equations (1) and (2) are applied to the pixels in the 1024th column, and the above equations (3) and (4) are applied to the pixels in the 1024th to 2047th columns. However, as shown in FIG. 19 (b), the origin (0,0) of the second image memory 6b is located not at the center but at the upper left, so that a correction for shifting the origin is required. Specifically, this second
Since the number of pixels of the image memory 6b is 2048 × 2048, the image processing device 6 uniformly adds 1024 to the X coordinate value obtained by the above equations (1) and (3), and After inverting the polarity of the Y coordinate value obtained in (2) and (4), a correction of uniformly adding 1024 must be made.

Summarizing the above, the image processing device 6 applies the following to the pixels in the k-th row and the m-th column (m = 0 to 1024) in the first image memory 6a shown in FIG. Execute equations (1 ′) and (2 ′). Px = 1024 + (1024-m) sin kθ (1 ′) Py = 1024- (1024-m) cos kθ (2 ′) And, based on the obtained values of Px and Py, FIG.
The pixel in the Py row and the Px column in the second image memory 6b shown in (b) is specified as the pixel after the conversion. And the first
The data written to the pixels in the k-th row and the m-th column in the image memory 6a is replaced with the data in the Py-th row and P in the second image memory 6b.
Transfer to the pixel in the x-th column.

On the other hand, the image processing device 6 operates in the k-th row and the m′-th column (m ′ = m ′) in the first image memory 6a shown in FIG.
The following equations (3 ′) and (4 ′) are executed for the pixels of Nos. 1025 to 2047). 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.
9 (b), the line Px ′ in the second image memory 6b, P
The pixel in the y'th column is specified as a pixel after conversion. Then, the data written to the pixels in the k-th row and the m-th column in the first image memory 6a is replaced with the data in the P in the second image memory 6b.
The data is transferred to the pixel in the x'th row and the Py 'column.

After the completion of the transfer, the image data stored in the second image memory 6b is substantially conjugate with the image data obtained by imaging the optical member 9 to be inspected by the area sensor, and 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 6
Performs the pass / fail judgment based on the image data stored in the second image memory 6b. In particular,
The image processing device 6 compares the luminance of each pixel of the image data stored in the second image memory 6b with a predetermined threshold, sets the value of a pixel brighter than the predetermined threshold to “1”, and sets the other pixels to “1”. A binarization process for setting the pixel value 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 9 is defective. <Control Processing> Next, the contents of the control processing executed by the image processing apparatus 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. .

The control process shown in FIG. 20 is started when an inspection start button (not shown) connected to the image processing device 6 is pressed. In the first S01 after the start, the image processing device 6 starts outputting a control signal to the motor drive circuit 7. Motor drive circuit 7 receiving this control signal
As described above, the image rotator 14 rotates the diffusion plate 2, the light shielding plate 8, and the auxiliary lighting devices 10 and 10 at a first rotation speed in the clockwise direction as viewed from the imaging device 3 side.
Is rotated at a second rotation speed at a constant speed in a counterclockwise direction as viewed from the imaging device 3 side.

In the next S02, the image processing device 6 inputs the image data for one scan output from the imaging device 3, and
Writing to the first image memory 6a. In the next S03, the image processing device 6 checks whether 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 6a by writing the image data in S02. If the image data in the polar coordinate system corresponding to the entire inspection target optical member 9 has not been synthesized, the process returns to S02, and the image data output from the imaging device 3 by 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 device 6 writes the image data in the first image memory 6a in S04. 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 6b.

In the next S05, the image processing device 6 sets the second
A binarization process is performed on the image of the entire inspection target optical member 9 in the rectangular coordinate system written in the image memory 6b. That is, the brightness of all pixels of the image data stored in the second image memory 6b is compared with a predetermined threshold. Then, the value of a pixel whose luminance is higher than the predetermined threshold is set to “1”.
And the value of a pixel whose luminance is lower than the predetermined threshold value is replaced with “0”.

In the next S06, the image processing device 6
The total number of pixels (dots) having a value of "1" in the image memory 6b is measured, and it is checked whether the number of pixels (dots) having a value of "1" is larger than a predetermined reference value. And a pixel (dot) having a value of “1”
If the number is larger than the predetermined determination reference value, in S07, it is determined that the inspection target optical member 9 is defective, and the fact is output to the outside (image display, audio output).
On the other hand, when the number of pixels (dots) having a value of “1” is equal to or less than the predetermined determination reference value, in S08, the inspection target optical member 9 is determined to be non-defective, and
This is output 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 judgment in S06.
The determination may be made based on whether or not the diameter of a region formed of a set of pixels having the value of “1” is equal to or larger than a predetermined value, or “1”.
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 values of? <Operation of the Embodiment> According to the first embodiment configured as described above, light that can pass through the inspection target optical member 9 and enter the image pickup lens 4 and also enter each pixel of the image pickup device 5. Are previously shielded on the light-shielding plate 20 by the light-shielding plate 8. 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 that has entered the region from the side of the light-shielding plate 8 is caused by the optical defect. The light is diffused 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, 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 column) does not change. Therefore, the angle of incidence of light that enters the imaging target region in 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.

In the present embodiment, the light shielding plate 8 is rotated at the first rotation speed around the optical axis 1 of the imaging lens 4 and, at the same time, the image rotator 14 is rotated in the direction opposite to the rotation direction of the light shielding plate 8. It is rotated in the direction at a second rotation speed which is １ ／ of the first rotation speed. Therefore, the shadow of the light-shielding plate 8 always covers the pixel rows of the image sensor 5, and the imaging target area of the inspection target optical member 9 rotates around the optical axis l. As a result, image data corresponding to the entire surface of the optical member 9 to be inspected can be obtained.

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 pixels (brightness) higher than a predetermined determination reference value in the converted image data in the rectangular coordinate system ( Dot)
Is measured, and the measured number of pixels (dots) is compared with a certain reference value. According to the result of the comparison, it is objectively determined whether the product is good or defective. <Modification of Embodiment> The above-described detection of an optical defect portion by the diffused light is established even if the direction of light incident on the area to be imaged by the imaging device 5 on the surface of the optical member 9 to be inspected is only one direction. I do. Therefore, the above-described light shielding plate 8
, A substantially semicircular light shielding plate 8a as shown in FIG.
May be used.

When the optical member 9 to be inspected contains a cylindrical component (anamorphic lens, cylindrical lens, etc.), the refractive power of the optical member 9 to be inspected changes depending on the circumferential direction. Therefore, the imaging device 3
When viewed from the position, the light-shielding plate 8 seen through the optical member 9 to be inspected is moved as shown in FIG. 22 or FIG. 23 as the optical member 9 to be inspected seen from the imaging device 3 relatively rotates.
As shown in the figure. In such a case, even if such a distortion occurs, the light transmitted through the inspection target optical member 9 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 light-shielding plate 8b of the shape which the width | variety gradually expanded toward the outer edge side. By employing the light-shielding plate 8b having such a shape, the detection accuracy near the optical axis 1 is improved, and at the same time, it is possible to at least prevent the possibility of erroneously recognizing a normal portion as a defective portion also near the periphery. Also in this case, instead of the light shielding plate 8b, FIG.
A substantially semicircular light shielding plate 8c shown in FIG. 5 may be used.

[0062]

Embodiment 2 The second embodiment of the present invention is different from the first embodiment in that the image memories 6a and 6b
And the control processing by the image processing device 6 is performed according to the flowchart shown in FIG. The control process according to the flowchart in FIG. 26 is to directly execute the binarization process and the determination process on the image data of each line input from the image sensor 5.

The control process according to the flowchart of FIG. 26 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 control signal to the motor drive circuit 7. As described above, the motor drive circuit 7 receiving this control signal makes the diffusion plate 2
Then, the light shielding plate 8 is rotated clockwise at a first rotation speed at a constant speed, and the image rotator 14 is rotated counterclockwise at a second rotation speed at a constant speed.

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 S13, the image processing device 6 executes the processing in 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
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 S16, the image processing device 6 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 6 returns the process to S12, 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, 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 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 In S17, the optical member 9 to be inspected is determined to be non-defective in S17, and the fact is output to the outside (image display, sound output). Then, thereafter, the control process is terminated.

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

[0071]

According to the optical member inspection apparatus of the present invention configured as described above, it is possible to judge whether or not a non-defective product is acceptable 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 sectional view showing a schematic configuration of an optical member inspection apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory view of the image rotator 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 bottom view of the diffusion plate holder 19 of FIG. 1 as viewed from the lower side of FIG. 1;

FIG. 5 is a partial sectional view taken along line VV in FIG. 1;

FIG. 6 is a side cross-sectional view in which an optical path in an image rotator at an initial position is developed and an optical axis is linearized in order to show a traveling state of light when an optical member to be inspected has no optical defect.

FIG. 7 is a side cross-sectional view in which an optical path in an image rotator at an initial position is developed and an optical axis is linearized in order to show the progress of light when an optical member to be inspected has an optical defect.

FIG. 8 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. 9 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. 10 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. 11 is a longitudinal sectional view showing a state where illumination light is transmitted through the scratch or crack shown in FIG. 10;

FIG. 12 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 orthogonally to a longitudinal direction of the light shielding plate.

FIG. 13 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. 14 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. 15 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. 16 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. 17 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. 18 is a diagram showing a coordinate conversion method from a polar coordinate system to a rectangular coordinate system.

FIG. 19 is a memory map showing image data stored in each image memory of FIG. 1;

20 is a flowchart showing the contents of control processing executed in the image processing apparatus of FIG.

FIG. 21 is a plan view showing a modification of the light shielding plate.

FIG. 22 is a plan view showing a state in which the light shielding plate looks distorted;

FIG. 23 is a plan view showing a state in which the light shielding plate looks distorted;

FIG. 24 is a plan view showing a modification of the light shielding plate.

FIG. 25 is a plan view showing a modification of the light shielding plate.

FIG. 26 is a flowchart illustrating the contents of control processing executed by the image processing apparatus according to the second embodiment of the present invention;

[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 motor drive circuit 8 light shielding plate 9 inspection target optical member 10 auxiliary lighting device 14 image rotator 15 image rotator holder 18 image rotator drive motor 19 diffusion plate Holder 22 Diffusion plate drive motor 23 Object holder

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP 9-5249 (JP, A) JP 9-5248 (JP, A) JP 53-7288 (JP, A) JP 4 265847 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G01N 21/84-21/956 G01M 11/00

Claims (10)

(57) [Claims] 1. An optical member inspection apparatus for detecting an optical defect of an optical member to be inspected, comprising: an imaging lens; and an object side of the imaging lens rotatably disposed around an optical axis of the imaging lens. An image rotator, a fixing member for fixing the inspection target optical member on the optical axis opposite to the imaging lens with the image rotator interposed therebetween, and an inspection target optical fixed to the fixing member with respect to the imaging lens A line sensor disposed at a position conjugate with the member, and an illumination light diffused toward the inspection target optical member on a side opposite to the image rotator across the inspection target optical member fixed to the fixing member. A diffusing plate, and an optical path of illumination light that is transmitted through the optical member to be inspected and is incident on the imaging lens, and then is incident on the imaging device. A light-blocking member that blocks between the optical member to be inspected, a first rotation mechanism that rotates the light-blocking member about the optical axis, and a rotation of the light-blocking member that is performed by the first rotation mechanism. A second rotation mechanism that rotates the image rotator so that a shadow of the light blocking member formed by the imaging lens always covers the line sensor; and an optical element of the optical member in an image captured by the imaging device. An optical member comprising: digitizing means for digitizing a portion indicating a defect; and judging means for judging whether a numerical value digitized by the digitizing means has exceeded a predetermined judgment reference value. Inspection equipment. 2. The magnification of the photographing lens is adjusted such that the entire area of the optical member to be inspected in the diameter direction intersecting with the optical axis is imaged by the line sensor. Optical member inspection device. 3. The optical member inspection apparatus according to claim 1, wherein the light shielding member has a band shape extending in a direction perpendicular to the optical axis. 4. When the image rotator rotates by a predetermined angle around the optical axis, the position of a light beam emitted from the image rotator rotates around the optical axis by an angle twice the predetermined angle. The optical member inspection device according to claim 1, wherein: 5. The inspection of an optical member according to claim 4, wherein said second rotation mechanism rotates said image rotator at half the rotation speed of said light shielding member by said first rotation mechanism. apparatus. 6. A digital camera according to claim 1, wherein said digitizing means measures a length of a portion of the image data output from said line sensor for each line where the luminance exceeds a predetermined threshold value. 2. The optical member inspection device according to 1. 7. The polarizer system according to claim 1, wherein said digitizing means reconstructs image data of a polar coordinate system corresponding to the whole optical member to be inspected based on image data of each line outputted from said line sensor. 2. The optical member inspection according to claim 1, wherein the data is converted into image data of a rectangular coordinate system, and the number of pixels whose luminance exceeds a predetermined threshold value in the image data of the rectangular coordinate system is measured. apparatus. 8. The optical member inspection apparatus according to claim 3, wherein the light shielding member has a band-like shape that expands from a portion intersecting the optical axis of the inspection target optical member toward an end. . 9. The first rotation mechanism rotates about the optical axis together with the light shielding member, and illuminates a portion of the inspection target optical member imaged by the imaging means from near an end of the light shielding member. The optical member inspection device according to claim 2, further comprising an auxiliary lighting device. 10. The apparatus according to claim 1, wherein the second rotation mechanism rotates the image rotator in a direction opposite to a rotation direction of the light blocking member by the first rotation mechanism.
Or the optical member inspection device according to 5.