JP2000019060A - Optical member-inspecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical member-inspecting apparatus which can detect flaws and cracks on a front face of an optical member to be inspected irrespectively of a direction of the flaws and cracks. SOLUTION: An image pickup device 13 linearly picks up an image of an optical member 14 to be inspected. A diffuse transmission plate 2 and a shading plate 9 illuminate an area to be picked up of the optical member 14 from the outside of a pickup optical axis of the image pickup device 3. A holder 19 holding the optical member 14 to be inspected is mounted on a rotary part hold stage 8 in a manner to be freely rotatable. A rotation motor 17 drives to rotate the holder 19. The rotary part hold stage 8 is fixed on a slider 13 moving linearly along a rail 7. A linear motor 12 drives to linearly move the slider 13. A control device 6 drives the image pickup device 3 to pick up the image while linearly driving the rotary part hold stage 8, then rotates the holder 19 by 90 deg., again drives the image pickup device 3 to pick up the image with linearly moving the rotary part hold stage 8. The control device 6 judges on the basis of image data obtained in the process whether or not the optical member 14 to be inspected is good.

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 a cause of a defect 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 lint or the like is mixed in the optical member during the formation of 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, Since the incident light flux is disturbed, desired performance cannot be obtained.

[0003] For this reason, various optical member inspection apparatuses for automatically detecting the cause of a defect in an optical member and automatically determining the quality of the optical member have been proposed. For example, in Japanese Patent Application No. 9-50760, the present applicant takes an image of an optical member to be inspected by using an image pickup device including an image pickup lens and a line sensor, and based on image data obtained by this image pickup, An optical member inspection device that determines the quality of an optical member,
Proposed. The optical member inspection device includes an imaging device including a line sensor and an imaging lens, a band-shaped light shielding member parallel to the line sensor disposed on a surface of the inspection target optical member opposite to the imaging device, and a light shielding member. And a diffusion plate for irradiating the inspection target optical member with illumination light from both sides. Then, the diffused light is generated from the cause of the defect by the irradiation light irradiated from the diffusion plate, and an image of the cause of the defect due to the diffused light is taken by the imaging device, and the inspection target optical member is orthogonal to the optical axis of the imaging optical system. Scanning is performed in a plane to obtain image data corresponding to the entire inspection target optical member. This scanning is performed in a direction orthogonal to the line sensor or in a direction rotating about the optical axis of the inspection target optical member. Then, the above-described pass / fail determination is made based on the image data obtained during the scanning.

[0004]

However, when the defect factor is a linearly extending flaw or crack, there is a problem that the inspection becomes inaccurate because these have directivity to incident light. That is, when the scratch or crack and the line sensor are oriented in directions orthogonal to each other, even if the scratch is irradiated with illumination light from both sides of the light-shielding plate, FIG.
As shown in (1), since diffused light toward the imaging lens is unlikely to occur, images of these flaws or cracks are not formed on the line sensor. Therefore, these flaws or cracks are not detected as defective factors.

In the above-mentioned Japanese Patent Application No. 9-50760, in order to solve this problem, an auxiliary light source for illuminating the optical system to be inspected from both ends in the major axis direction of the light shielding member is added.
Although diffused light is also generated from scratches or cracks in the direction orthogonal to the direction of the line sensor, the incident angle of illumination light increases, so that diffused light can be efficiently incident on the imaging lens. Can not.

Accordingly, an object of the present invention is to provide an optical member inspection apparatus capable of detecting a scratch or crack on the surface of an optical member to be inspected regardless of the direction of the scratch or crack.

[0007]

The present invention has the following features to attain the object mentioned above.

That is, the invention according to claim 1 is an optical member inspection apparatus for detecting an optical defect of an optical member to be inspected, wherein the imaging lens, the holder for holding the optical member to be inspected, and the imaging lens And a line sensor disposed at a position substantially conjugate to the inspection target optical member held by the holder, and light incident on the line sensor 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 passes from outside the optical path, and a surface substantially orthogonal to the optical axis of the imaging lens relative to the imaging lens, line sensor, and illumination means A rotating mechanism for rotating the holder by a predetermined angle within the holder, and the holder in a direction perpendicular to the optical axis direction of the imaging lens and the scanning direction of the line sensor. A linear movement mechanism for moving, the relative rotation of the holder relative to the rotation mechanism, and the linear sensor relative movement of the holder relative to the rotation mechanism before and after the relative rotation, respectively, from the line sensor Control means for outputting image data corresponding to the entire optical member to be inspected; image data corresponding to the entire optical member to be inspected output from the line sensor before the relative rotation of the holder; A quality determination unit configured to determine the quality of the inspection target optical member based on image data corresponding to the entire inspection target optical member output from the line sensor after the rotation.

According to the optical member inspection apparatus thus configured, the illuminating means is located outside the optical path of the light that enters the line sensor after passing through the optical member to be inspected and entering the imaging lens. . Therefore, the illumination light that has entered the inspection target optical member from the illumination means does not enter the line sensor after entering the imaging lens unless the inspection target optical member has an optical defect. Therefore, the image captured by the line sensor 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, 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. The control means instructs the rectilinear moving mechanism to move the holder in a rectilinear direction, thereby causing the optical member to be inspected to traverse the optical axis of the imaging lens, and the entire optical member to be inspected output from the line sensor during that time. To obtain image data corresponding to. Next, the control means instructs the rotation mechanism to rotate the holder relative to the holder, thereby rotating the inspection target optical member by a predetermined angle. After this rotation, the control means again instructs the rectilinear movement mechanism to move the holder relative rectilinearly, thereby causing the optical member to be inspected to cross the optical axis of the imaging lens, during which the output from the line sensor is output. Image data corresponding to the entire inspection target optical member. Each image data obtained in this manner is obtained by imaging the optical member to be inspected in a state where the line sensors are directed in different directions. The angle between the direction of the crack and the direction of the line sensor is different from each other. Therefore, the scratches or cracks that have disappeared in any one of the image data are also brightly reflected in the other image data. Therefore, the pass / fail determination means can accurately determine pass / fail of the optical member to be inspected based on both image data.

The rotation mechanism may rotate the holder with the line sensor, the imaging lens and the illumination means fixed, or rotate the line sensor, the imaging lens and the illumination means with the holder fixed. The rectilinear moving mechanism may move the holder in a straight line with the line sensor, the imaging lens and the illuminating unit fixed, or may move the line sensor, the imaging lens and the illuminating unit in a straight line with the holder fixed. Both the rotation mechanism and the linear movement mechanism
When fixing the line sensor, the imaging lens, and the illuminating means, a linear moving member that is linearly moved by a linear moving mechanism may be provided, a holder may be provided on the linear moving member, and the linear moving member may be rotated by a rotating mechanism.

The angle at which the rotation mechanism rotates relatively may be any angle except 0 and 180 degrees, but it is more desirable to approach 90 degrees, and most preferably 90 degrees.

Further, the optical member inspection apparatus according to claim 2 further comprises a rectilinear moving member, and the rotating mechanism is configured as a mechanism for rotating the holder with respect to the rectilinear moving member. The linear moving mechanism is
This is specified by being configured as a mechanism for linearly moving the linearly moving member in a direction orthogonal to the optical axis of the imaging lens.

Further, the optical member inspection apparatus according to the third aspect is characterized in that the predetermined angle of the first aspect is 90 °.

According to a fourth aspect of the present invention, there is provided an optical member inspection apparatus, wherein the pass / fail determination means of the first aspect performs the pass / fail judgment after combining the two image data.

According to a fifth aspect of the present invention, there is provided an optical member inspection apparatus, wherein the illuminating means of the first aspect is disposed at a position opposite to the imaging lens with respect to the inspection target optical member. A diffusion plate that diffuses illumination light toward the inspection target optical member, and blocks an optical path of light incident on the line sensor after passing through the inspection target optical member and entering the imaging lens between the inspection target optical member and the diffusion plate. A light shielding member.

According to a sixth aspect of the present invention, there is provided an optical member inspection apparatus, wherein the light shielding member according to the fifth aspect has a strip shape arranged in parallel with the line sensor.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. <Structure of Optical Member Inspection Apparatus> The schematic structure of the optical member inspection apparatus according to the present embodiment is shown in the front sectional view of FIG. As shown in FIG. 1, the illumination lamp 1, the diffusion plate 2, the object scanning unit M, and the imaging device 3 that constitute the optical member inspection device are arranged on the same optical axis l.

The image pickup apparatus 3 includes an image pickup lens 4 as a positive lens system, and a line sensor 5 (CCD line sensor) for picking up an image formed by light converged by the image pickup lens 4. In FIG. 1, the line sensor 5 is installed so as to direct its pixel column in the left-right direction. The pixel array of the line sensor 5 intersects the optical axis 1 of the imaging lens 4 perpendicularly at the center. Note that the imaging lens 4 is capable of moving forward and backward (adjusting the focus) with respect to the line sensor 5 in the imaging apparatus 3, and the imaging apparatus 3 itself is also capable of moving forward and backward in the optical axis l direction. It is attached to a frame (not shown).

The line sensor 5 picks up an image in a line at predetermined time intervals (a period in which electric charges are appropriately accumulated in each pixel), scans each pixel in the order in which the pixels are arranged, and accumulates each pixel. Output charge. The charges output from the line sensor 5 in this manner are subjected to predetermined amplification processing and A / D conversion processing and then input to the control device 6 shown in FIG. Is done.

The inspection object scanning unit M holds the inspection target optical member 14 at a position conjugate with the imaging surface of the line sensor 5 with respect to the imaging lens 4.
Is a device that relatively linearly moves the optical member 14 in a direction perpendicular to the optical axis of the imaging lens 4 and rotates the inspection target optical member 14 by 90 degrees. Hereinafter, a specific configuration of the subject scanning unit M will be described with reference to FIG. 1 and FIG. 2 which is a plan view as viewed from the position of the imaging device 3.

As shown in these figures, the object scanning unit M includes a rail 7 fixed to a lower portion of a frame (not shown) of the optical member inspection apparatus, and a rotating member slid along the rail 7. The unit holder 8 and the holder 19 rotatably mounted on the rotating unit holder 8 are configured as main components.

Of these, the rail 7 has its long axis directed in a direction orthogonal to the direction of the pixel column of the line sensor 5 and the direction of the optical axis l, and has a U-shaped cross section. ing. Both ends of the rail 7 are supported by support plates 10, 10
Is closed by A ball screw 11 is rotatably provided between the centers of the support plates 10 and 10. On the outer surface of one of the support plates 10, a linear motor 1 for driving the ball screw 11 is rotated.
2 are installed.

A slider 13 is slidably mounted on the upper surface of the rail 7. A ball nut 20 screwed to the ball screw 11 is fixed to a lower surface of the slider 13 (a surface facing the rail 7). Therefore, the slider 13 moves forward / backward on the rail 7 by the forward / reverse rotation of the ball screw 11 by the linear motor 12. The movable distance of the slider 13 is longer than the diameter of the optical member 14 to be inspected. These rails 7, both support plates 10, 10, ball screw 11, motor 12 for straight running
And the slider 13 moves the holder 1 in a direction orthogonal to the direction of the optical axis of the imaging lens 4 and the scanning direction of the line sensor 5, respectively.
9 corresponds to a rectilinear moving mechanism that moves rectilinearly.

The above-mentioned rotating section holding base 8 functioning as a linearly moving member has a vertically L-shaped vertical cross section, and its base end is vertically fixed on the upper surface of the slider 13. . Therefore, the upper surface of the rotating unit holder 8 is perpendicular to the optical axis l. The tip of the rotating part holder 8 crosses the optical axis l. A circular through-hole 8a centered on a center line that can coincide with the optical axis 1 is bored at the tip. The edge of the through hole 8a on the imaging device 3 side forms a cylindrical edge 8b protruding in a cylindrical shape. The holder 19 described above is rotatable by being fitted to the cylindrical edge 8b. That is, the holder 19 is provided with the through hole 8a.
It has a substantially cylindrical shape having the same inner diameter as that of the above, and its lower end opening is formed slightly larger in diameter than the outer diameter of the cylindrical edge portion 8b,
The large-diameter portion 19a is fitted to the cylindrical edge 8b of the rotating portion holding base 8.

An annular inner flange 19b is formed at the center of the inner surface of the holder 19 in the axial direction so as to protrude. Since the inner diameter of the inner flange 19b is smaller than the outer diameter of the optical member 14 to be inspected, the inner flange 19b can hold the outer edge of the optical member 14 to be inspected. Further, an annular gear 15 is provided on the outer surface of the holder.
Is filled.

On the other hand, a rotating motor 17 is fixed on the upper surface of the rotating portion holder 8 via a stay 16. The drive shaft of the rotation motor 17 is parallel to the optical axis l, and a pinion gear 18 that meshes with the annular gear 15 is attached to the tip of the drive shaft. Accordingly, when the rotation motor 17 drives the pinion gear 18 to rotate, the holder 19 and the inspection target optical member 14 held by the holder 19 rotate about the optical axis l. However, the rotation angle of the holder 19 is limited to a range of 90 degrees by a limiter (not shown). The rotation motor 17, the pinion gear 18, and the annular gear 15 correspond to a rotation mechanism that rotates the holder 19 by a predetermined angle in a plane substantially orthogonal to the optical axis 1 of the imaging lens 4.

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.

As shown in FIG. 2, a long side sufficiently longer than twice the diameter of the optical member 14 to be inspected is provided between the object scanning unit M and the illumination lamp 1 on the optical axis l. A rectangular diffuse transmission plate 2 having a short side sufficiently longer than the diameter of the target optical member 14 is fixed with its long side directed parallel to the axis of the rail 7. Since the surface of the diffuse transmission plate 2 (the surface on the side of the inspection target optical member 14) is processed as a rough surface, the diffusion transmission plate 2 receives the illumination light emitted from the illumination lamp 1 on the entire back surface thereof. ,
The light can be diffused toward the inspection target optical member 14.

At the center of the upper surface of the diffuse transmission plate 2 in the long side direction, a light shielding plate 9 as a band-shaped light shielding member is attached. As shown in FIG. 1, the light shielding plate 9 has its longitudinal direction directed to the short side of the diffuse transmission plate 2 with its center aligned with the optical axis l of the imaging lens 4. As shown in FIG. 4, which is a schematic view showing a state seen from the direction of arrow IV in FIG. 1, the width of the light shielding plate 9 is the distance between the marginal rays m, m of the light incident on each pixel of the line sensor 5. Wider than. These imaging device 1, diffuse transmission plate 2 and light shielding plate 9
Correspond to lighting means.

The above-mentioned motors 12 and 17 are controlled and controlled by a control device 6 whose internal circuit configuration is shown in FIG.
Driven. The control device 6 determines whether the inspection target optical member 27 is a good product or a defective product based on image data input from the imaging device 3 while supplying a drive current to each of the motors 12 and 17. The device is equivalent to a control unit and a pass / fail determination unit. Hereinafter, the internal circuit configuration will be described with reference to FIG.

As shown in FIG. 3, the control device 6 comprises a CPU 60 and a frame memory 6 connected to each other via a bus B.
1, from the host memory 62 and the motor drive circuit 63,
It is configured.

The frame memory 61 is a buffer in which image data input from the imaging device 3 is written.

The host memory 62 has an image memory area 62
a, a working memory area 62b, and an image processing program storage area 62c. The image memory area 62a is an area in which the image data written in the frame memory 61 is written every predetermined time from the top row in row units. Further, the working memory area 62b is
0 is an area where image processing is performed. The image processing program storage area 62c is an area as a computer-readable medium for storing an image processing program executed by the CPU 60.

The motor drive circuit 63 supplies a drive current for driving each of the motors 12 and 17 at a desired speed and a desired amount to each of the motors 12 and 17 in accordance with a command from the CPU 60.

The CPU 60 is a computer for controlling the control device 6 as a whole. That is, the CPU 60 executes the image processing program stored in the image processing program storage area 62d of the host memory 62, and
The image data written in the frame memory 61 is periodically copied to the image memory area 62a of the host memory 62 while rotating the camera 2 at a constant speed.
At the time when the image data corresponding to the entire inspection target optical member 14 is synthesized, after binarizing the image data using a predetermined threshold value and masking unnecessary portions,
This image data is added to the working memory 62b (corresponding to control means). The CPU 60 executes such control before and after the rotation of the holder 19 by 90 degrees by the rotation motor 17, and based on the image data accumulated in the working memory 62b, determines whether the inspection target optical member 14 is good or not. Execute (corresponds to pass / fail determination means). <Principle of Optical Defect Detection> In the optical member inspection apparatus configured as described above, in the plane of FIG. 4, light that can enter the imaging lens 4 and enter each pixel of the line sensor 5 is reflected by the imaging lens. 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. 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 diffuse transmission plate 2.
Then, on the diffuse transmission plate 2, the peripheral light rays m, m
Is shielded by the light shielding plate 9. Therefore, as shown in FIG. 4, the imaging target area of the inspection target optical member 14 by the line sensor 5 (a part conjugate with the light receiving surface of the pixel array of the line sensor 5 with respect to the imaging lens 4 and its vicinity in the optical axis direction, FIG. (Indicated by a two-dot chain line in FIG. 7), there is no light incident on each pixel of the line 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 area in the inspection target optical member 14 but passes through the outside of the marginal rays m, m. Does not enter. The light diffused from the side of the light shielding plate 9 on the surface of the diffusion transmission plate 2 and transmitted through a portion other than the imaging target region in the inspection target optical member 14 can enter the imaging lens 4, but the line sensor 5. Are not converged on each pixel. Therefore, the image data output from the imaging device 3 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, when there is a defect factor K in the imaging area on the surface of the optical member 14 to be inspected, FIG.
As shown in (1), when the light n diffused from the side of the light shielding plate 9 on the surface of the diffusion transmission plate 2 hits the defect factor K, the light n is diffused by the defect factor K. 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 line sensor 5 via the imaging lens 4. Therefore, an image of the defect factor K (an image brighter than the surroundings) is formed on the imaging surface of the line sensor 5.

The scratches and cracks have directivity to incident light. 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. 6, when the flaw or crack K is formed in parallel with the longitudinal direction of the light shielding plate 9, the light shielding plate 9 on the surface of the diffusion transmission plate 2 is formed.
The light n diffused from the side part of the light enters the scratch or crack K so as to be orthogonal to the light, so that the diffused light n ′ is generated as described above, and a part of the diffused light n ′ is
And an image of the flaw or crack K is picked up by the line sensor 5. On the other hand, as shown in FIG. 7, when the scratches or cracks K are formed along the direction orthogonal to the longitudinal direction of the light shielding plate 9, along the direction orthogonal to the longitudinal direction of the light shielding plate 9. As shown in FIG. 8 which is a vertical sectional view of FIG. 8, light n diffused from the side of the light shielding plate 9 on the surface of the diffusion transmission plate 2 is incident parallel to the scratches or cracks K. Is transmitted as it is without being diffused. And this light n is a marginal ray m, m
Does not enter the imaging lens 4. Therefore, the image of the scratch or the crack K is not captured by the line sensor 5.

In order to solve such a problem, in the present embodiment, the scanning unit optical member 14 is scanned with respect to the image pickup apparatus 3 by moving the rotating unit holding table 8 straight, and then the holder 19 is moved. The optical member 14 to be inspected is 9
The inspection target optical member 1 is rotated with respect to the imaging device 3 by rotating the rotation unit holding table 8 linearly again by rotating it by 0 degrees.
4 was scanned. As a result, all the scratches and cracks K formed on the inspection target optical member 14 have an angle of 45 degrees or less with respect to the longitudinal direction of the light shielding plate 9 in one of the scans. As described above, the angle of the scratch or crack K with respect to the longitudinal direction of the light shielding plate 9 is at most 45 °.
However, if the angle is 45 degrees, diffused light n ′ sufficient to form these scratches or cracks K on the line sensor 5 can be generated. <Control Processing> Next, in order to determine whether the optical member 14 to be inspected is a non-defective product or a defective product, a control program in the image processing program storage area 62c is read.
The contents of the control processing executed by the PU 60 will be described with reference to the flowchart of FIG.

The control process shown in FIG. 9 is started when an unillustrated inspection start button connected to the control device 6 is pressed. In the first S01 after the start, the CPU 60
Performs initialization of the entire optical member inspection apparatus. That is, the rotating unit holder 8 is returned to the initial position (the uppermost position in FIG. 2, that is, the position where the imaging target area of the imaging device 3 is outside the inspection target optical member 14) with respect to the motor drive circuit 63. At the same time, an instruction is given to return the rotational position of the holder 19 to the initial position. Upon receiving this instruction, the motor drive circuit 63 supplies a drive current to each of the motors 12 and 17 according to the instruction. Further, the CPU 60 initializes a variable i used for control to “0”. In addition, PCU60
Clears the contents stored in the work memory area 62b.

In the next step S02, the CPU 60 instructs the motor drive circuit 63 to slide the rotating unit holder 8 downward at a constant speed in FIG. Upon receiving this instruction, the motor drive circuit 63 rotates the linear motor 12 at a constant speed in order to start the slide movement.

In the next S03, the CPU 60 writes the image data for one scan input from the image pickup device 3 to the frame memory 61 in the image memory area 62a.

In the next S04, the CPU 60 writes the image data in S03, and the
It is checked whether or not the image data corresponding to the entire inspection target optical member 14 has been synthesized in a. If the image data corresponding to the entire inspection target optical member 14 has not yet been synthesized, the process returns to S03, and the image data input from the imaging device 3 to the frame memory 61 by the new imaging is stored in the image memory. Write to area 62a.

On the other hand, when the image data corresponding to the entire inspection target optical member 14 is synthesized, the CPU 6
In step S05, the binarization process is performed on the image data written in the image memory area 62a and corresponding to the entire inspection target optical member 14. That is, the brightness values of all the pixels of the image data stored in the image memory area 62a are compared with a predetermined threshold value. Then, the luminance value of a pixel whose luminance is higher than the predetermined threshold is replaced with “1”, and the luminance value of a pixel whose luminance is lower than the predetermined threshold is replaced with “0”.

In the next S06, the CPU 60 executes a mask process. The reason for performing the mask processing will be described with reference to FIGS. Now, the inspection target optical member 1
It is assumed that reference numeral 4 is an optical member having power in a radial direction about the optical axis, such as a circular lens. At this time, when the light-shielding plate 9 is moved straight in the diameter direction of the inspection target optical member 14, the light-shielding plate 9 viewed from the position of the imaging device 3 through the inspection target optical member 14 has a concave lens 14a. 11A to 11C, and changes as shown in FIGS. 12A to 12C if the inspection target optical member 14 is a convex lens 14b. As described above, when the optical axis of the inspection target optical member 14 is deviated from the center of the light shielding plate 8, the inspection target optical members 14a, 1
The position of the light-shielding plate 9 seen through 4b appears to be shifted from the actual position. As a result, even if the inspection target optical member 14 has no optical defect, light diverging from the side of the light shielding plate 9 in the diffusion transmission plate 2 enters the imaging lens 4 and an image captured by the line sensor 5 It becomes bright. For this reason, a bright image of an optical defect may not be emphasized much, and a portion that is not an optical defect may be determined to be an optical defect. Therefore, in S06, of the image data (binarized data in the image memory area 62a) obtained by each scan, the initial imaging of the inspection target optical member 14 (see FIGS. 11A and 12A). ) And the region obtained at the end of imaging (see FIGS. 11C and 12C)
Mask it. That is, when scanning is performed in the direction of 0 ° shown in FIG. 10, the luminance values of all the pixels included in the α and β regions are rewritten to “0”, and 90 ° shown in FIG.
When the scanning is performed in the direction of, the luminance values of all the pixels included in the γ and δ regions are rewritten to “0”.

In the next S07, the CPU 60 superimposes the image data (masked binarized data) in the image memory area 62a on the work memory area 62b. The superimposition of the image data is performed by adding the luminance value of each pixel constituting the image data to the luminance value of each pixel in the work memory area 62b.

In the next S08, the CPU 60 checks whether or not the variable i has reached "1". If the variable i is “0” (that is, at the time of scanning in the 0 ° direction before the rotation of the holder 19), the CPU 6
If "0", the process proceeds to S09.

In S09, the CPU 60 increments the variable i by one. In the next S10, the CPU 60
It instructs the motor drive circuit 63 to rotate the holder 19 by 90 °. Upon receiving this instruction, the motor drive circuit 63 performs the rotation by using the rotation drive motor 17.
To supply the drive current. In the next S11, the CPU 60
Instructs the motor drive circuit 63 to return the rotating section holder 8 to the initial position. Upon receiving this instruction, the motor drive circuit 63 rotates the straight traveling motor 12 in the direction opposite to S02. After S11, the CPU 60 returns the process to S02, and performs scanning in the 90 ° direction. In S07 in the scanning in the 90 ° direction, CP
U60 rotates the image data stored in the image memory area 62a by -90 °, and sets the luminance value of each pixel constituting the image data to the luminance value of the corresponding pixel in the work memory area 62b. Add each one. As a result, the image data stored in the work memory area 62b is 0 °
The image obtained by scanning in the direction is superimposed on the image obtained by scanning in the 90 ° direction.

On the other hand, when it is determined that the variable i has reached “1” (that is, at the time of scanning in the 90 ° direction after the rotation of the holder 19), the CPU 60 executes the processing in S1.
Proceed to 2. In S12, the CPU 60 measures the total number of pixels having a value of “1” in the work memory area 62b and checks whether the total number of pixels having a value of “1” is larger than a predetermined determination reference value. I do. And
If the total number of pixels having a value of “1” is larger than the predetermined determination reference value, in S13, it is determined that the inspection target optical member 14 is defective, and that fact is output to the outside (image display). , Voice output). On the other hand, when the total number of pixels having the value of “1” is equal to or smaller than the predetermined determination reference value, in S14, the inspection target optical member 14 is determined to be non-defective, and the fact is determined to the outside. Output (image display,
Audio output). After the above, the CPU 60 ends the control processing.

Note that "1" is used instead of the determination in S12.
May be determined based on whether the diameter of the region consisting of a set of pixels having a value of not less 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 of “1” is equal to or larger than a predetermined value. <Operation of Embodiment> The inspection of the optical member inspection apparatus according to the present embodiment having the above-described configuration will be described below.

The operator first checks the optical member 1 to be inspected.
4 is set in the holder 19, the illumination lamp 1 is turned on, and the power of the imaging device 3 is turned on. This allows
The imaging device 3 inputs image data obtained by linearly imaging the imaging target area to the control device 6. However, at this point, since the control device 6 has not executed the processing of FIG. 9, the image data input to the control device 6 is not taken into the image memory area 62a.

Next, the operator presses an inspection start button (not shown) connected to the control device 6. Then, the holder 19 is returned to the position of 0 °, and the rotating portion holder 8 together with the holder 19 is returned to the uppermost initial position in FIG. 2 (S01). In this manner, when the entire apparatus is initialized, the CPU 60 executes scanning in the 0 ° direction. That is, while holding the holder 19 at the position of 0 °, the rotation holding unit 8 is moved downward at a constant speed in FIG.
2). Then, during this constant speed movement, the CPU 60 writes the image data input from the imaging device 3 to the frame memory 61 in the image memory area 62a. As a result, image data corresponding to the entire inspection target optical member 14 is synthesized in the image memory area 62a (S03, S0).
4). In this image data, when the scratches or cracks having the same shape and the same size are compared with each other, the scratches and cracks that are oriented at 0 ° with respect to the longitudinal direction of the light shielding plate 9 appear brightest. And the light shielding plate 9
As the angle with respect to the longitudinal direction increases, the reflection of scratches and cracks on image data becomes darker, and
Scratches and cracks oriented at 90 ° to the longitudinal direction have disappeared in the image data.

After the image data is subjected to the binarization processing (S05), the areas (areas α and β in FIG. 10) which are generally brightened by noise are masked (S0).
6) is written to the working memory area 62b (S0
7).

Next, the CPU 60 moves the holder 19 by 90 °.
(S10), and the rotating section holder 8 together with the holder 19 is returned to the initial position (S11). After that, the CPU 60 executes scanning in the 90 ° direction. That is, while holding the holder 19 at the 90 ° position, the rotation holding unit 8 is moved downward at a constant speed in FIG. 2 (S02).
During the constant speed movement, the CPU 60 converts the image data input from the imaging device 3 into the frame memory 61,
Write to the image memory area 62a. As a result, in the image memory area 62a, image data corresponding to the entire inspection target optical member 14 is synthesized (S03, S04). In this image data, when the scratches or cracks having the same shape and the same size are compared with each other, the scratches and cracks that are oriented at 0 ° with respect to the longitudinal direction of the light shielding plate 9 (when scanning in the 0 ° direction). The scratches and cracks that were oriented at 90 ° to the longitudinal direction of the light shielding plate 9)
Reflects brightest. Then, as the angle of the light-shielding plate 9 with respect to the longitudinal direction becomes larger, the reflection of the scratches and cracks on the image data becomes darker, and the scratches and cracks (0 °
When scanning in the direction of
The scratches and cracks facing in the direction of ° have disappeared in the image data.

After the image data has been subjected to the binarization process (S05), the regions (regions γ and δ in FIG. 10) which are generally brightened by noise are masked (S05).
06). Then, the image data is rotated by -90 ° and aligned with the image data obtained by scanning in the 0 ° direction stored in the working memory area 62b, and then is adjusted to the image data in the working memory area 62b. It is superimposed (S07).

As a result of this superposition, the working memory area 62
In the image data held in b, flaws and cracks in all directions are reflected in the same size. Therefore, in the quality judgment after that (S12),
Accurate determination can be made based only on the number of pixels forming the image of each flaw and crack.

[0056]

According to the optical member inspection apparatus of the present invention configured as described above, it is possible to detect a flaw on the surface of the optical member to be inspected regardless of the direction of the flaw.

[Brief description of the drawings]

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

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

FIG. 3 is a block diagram showing a circuit configuration of a control device.

FIG. 4 is a diagram showing the progress of light when there is no defect factor in the optical member to be inspected.

FIG. 5 is a diagram showing the progress of light when there is a defect factor in the optical member to be inspected.

FIG. 6 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. 7 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. 8 is a longitudinal sectional view showing a state where illumination light is transmitted through the scratch or crack shown in FIG. 7;

FIG. 9 is a flowchart showing the contents of control processing executed by the CPU of FIG. 3;

FIG. 10 is an explanatory diagram of a masking target area in image data.

FIG. 11 is an explanatory diagram of how a light shielding plate looks when a concave lens is inspected by the optical member inspection apparatus of FIG. 1;

FIG. 12 is an explanatory diagram of how a light shielding plate looks when a convex lens is inspected by the optical member inspection apparatus of FIG. 1;

[Explanation of symbols]

 Reference Signs List 2 diffuse transmission plate 3 imaging device 4 imaging lens 5 line sensor 6 control device 7 rail 8 rotating unit holding stand 9 light shielding plate 11 ball screw 12 linear motor 13 slider 14 optical member to be inspected 17 rotation motor 19 holder

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Taichi Nakanishi F-term (reference) 2A05 AB20 BA20 CA03 CA04 DA07 EA11 EA12 EA14 EB01 EB01 ED01 in Asahi Kogaku Kogyo Co., Ltd. 2-36-9 Maeno-cho, Itabashi-ku, Tokyo ED07 2G086 EE08 FF05

Claims (6)

[Claims] 1. An optical member inspection apparatus for detecting an optical defect of an optical member to be inspected, comprising: an imaging lens; a holder for holding the optical member to be inspected; and the imaging lens held by the holder. A line sensor disposed at a position substantially conjugate to the inspection target optical member, and from outside the optical path of light incident on the line sensor after passing through the inspection target optical member and entering the imaging lens. Illuminating means for illuminating a portion of the optical member to be inspected through which the light passes; and the holder in a plane substantially perpendicular to the optical axis of the imaging lens relative to the imaging lens, line sensor, and illumination means. A rotation mechanism for rotating the lens by a predetermined angle, a direction of an optical axis of the imaging lens, and a movement of the line sensor relative to the imaging lens, the line sensor, and the illumination unit. A linear movement mechanism for linearly moving the holder in a direction orthogonal to each direction, and performing relative rotation of the holder with respect to the rotation mechanism, and before and after this relative rotation, respectively, with respect to the rotation mechanism, Control means for causing the line sensor to output image data corresponding to the entire inspection target optical member by causing the holder to move relatively straight; and the inspection target optical output from the line sensor before the relative rotation of the holder. Pass / fail judgment of the inspection target optical member based on image data corresponding to the entire member and image data corresponding to the entire inspection target optical member output from the line sensor after the relative rotation of the holder. An optical member inspection apparatus, comprising: a determination unit. 2. The apparatus according to claim 1, further comprising a rectilinear moving member, wherein the rotating mechanism is configured as a mechanism for rotating the holder with respect to the rectilinear moving member. 2. The optical member inspection device according to claim 1, wherein the optical member inspection device is configured as a mechanism for linearly moving in a direction orthogonal to the optical axis. 3. The optical member inspection apparatus according to claim 1, wherein said predetermined angle is 90 °. 4. The optical member inspection apparatus according to claim 1, wherein said quality judgment means performs said quality judgment after combining said two image data. 5. 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-blocking member that blocks an optical path of light incident on the line sensor after passing through the target optical member and entering the imaging lens between the inspection target optical member and the diffusion plate. 2. The optical member inspection device according to 1. 6. An optical member inspection apparatus according to claim 5, wherein said light shielding member has a band-like shape arranged in parallel with said line sensor.