JP2006220498A - Lens inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an lens inspection device detecting various flaws related to a lens inclusive of a flaw having optical strain, and also to provide a lens inspection method. <P>SOLUTION: A surface illumination panel 28 is arranged at one end of the optical axis OA direction of a lens 25 to be inspected so as to hold the lens 25 to be inspected, while an imaging CCD camera 36 is arranged at the other end. A light-shielding plate 33 having a pinhole 34 or a slit, which allows a part of the light from the surface illumination panel 28 to arrive at the lens 25 to be inspected, is arranged in between the surface of the surface illuminating panel 28 and the lens 25 to be inspected. The light arriving through the light and shade boundary part of the edge part of the pinhole 34 or slit of the light-shielding plate 33, is projected to the CCD camera 36 as almost parallel light via the lens 25 to be inspected. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lens inspection apparatus and a lens inspection method for inspecting appearance of a lens defect in a lens manufacturing process or the like. Here, even if a defect is present inside the lens, it is also assumed that the lens is visually recognized.

  In general, in a lens manufacturing process in which a lens is molded with a synthetic resin or the like, it is necessary to irradiate the molded lens with light to inspect the lens for defects such as scratches, foreign matter, and cracks. As a method for irradiating the inspection target lens with light in the appearance inspection of such a lens, a bright field illumination method, a dark field illumination method, and an edge light illumination method have been conventionally employed.

  That is, in the bright field illumination method, the entire lens is uniformly illuminated from below the inspection target lens, and the state of the lens is captured by the camera. According to this method, when the entire image is in a bright state and the lens has a defect such as a foreign object, the defective portion shields or scatters light from below to capture an image in a dark state. Is done.

  In the dark field illumination method, the lens to be inspected is illuminated from outside the field of view of the camera, and the state of the lens is imaged by the camera. According to this method, when the entire image is in a dark state and the lens has a defect such as a foreign object, the defective portion is imaged in a brightly lit state by refracting or reflecting light. .

  Further, in the edge light illumination method, light is introduced from the side surface of the inspection target lens, and a state in which the light is transmitted through the lens as a waveguide is imaged by a camera. According to this method, when the lens has a defect such as a scratch, light is extracted from the defective portion, and the state is imaged by the camera.

Patent Document 1 discloses a technique in which lens inspection is performed using a circular light source and a light shielding mask having a diameter slightly larger than the outer shape of the inspection target lens.
JP 2000-292307 A

  However, these conventional illumination methods in lens inspection have the following problems. In other words, in the bright field illumination method, if there is a defect with optical distortion or a flaw in the inspection target lens, the defective part is hidden in the light of the entire image, and the defect is removed. It could not be detected accurately.

  In addition, in the dark field illumination method, since defects other than defects such as particles are also shined, the determination of defects becomes unclear. Furthermore, when the inspection object is a lens, the line of sight seen from the camera is greatly bent, the field of view of the camera is increased, and the illumination that is in the dark field enters the field of view, which hinders detection of defects. did. Moreover, this dark field illumination method could not detect any defects having optical distortion such as pulse. Similarly, in the edge light illumination method, a defect having optical distortion such as a pulse cannot be detected at all.

  In addition, the technique described in Patent Document 1 also provides a simple transmission dark field, transmission bright field, and reflection plan field, and also reflects in the lens surface. It is difficult to detect the distortion, and it is also difficult to detect the engineering distortion such as the pulse.

  The present invention has been made paying attention to such problems existing in the prior art. An object of the present invention is to provide a lens inspection apparatus and a lens inspection method capable of detecting various defects relating to the lens including defects having optical distortion.

  In order to achieve the above object, according to the first aspect of the present invention, a light source is disposed on one side in the optical axis direction with the lens to be inspected in between, and an imaging unit is disposed on the other side, and light from the light source is disposed. Adjustment means for adjusting the position in the optical axis direction is provided so that the image pickup means can take an image of a light / dark boundary portion. The light-shielding means for shielding a part of the light from the light source is arranged.

According to a second aspect of the present invention, in the first aspect of the present invention, the light shielding means is disposed on a light source.
(Function)
In the present invention, the light from the inspection object lens is set to be substantially parallel light. In this state, when the parallel light from the lens to be inspected is imaged by the camera, the image including the bright / dark boundary portion becomes a substantially uniform gray image. If there is any defect on the lens to be inspected, that is, if there is a light-shielding defect such as a scratch or a stain, the image signal of the defective portion will be darkened and optical distortion such as pulsation will occur. When there is a defect having a defect, the image signal of the defective part changes to bright and dark due to the lens action. Therefore, it is possible to clearly detect various defects relating to the lens including defects having optical distortion. In particular, in the present invention, the boundary between light and dark will be seen, in other words, light from the light and dark boundary will mainly enter the imaging means, and therefore optical distortion defects can be detected more clearly. Is possible.

  As described above, according to the present invention, it is possible to easily and appropriately detect various defects relating to the lens including defects having optical distortion.

(First embodiment)
Below, 1st Embodiment of this invention is described based on FIGS. 1-3.
As shown in FIG. 1, in the lens inspection apparatus of this embodiment, the pallet holder 21 is arranged so as to be movable in the X direction and the Y direction in the horizontal plane via the X direction moving stage 22 and the Y direction moving stage 23. It is installed. A lens support pallet 24 is detachably mounted on the pallet cradle 21, and a plurality of set holes 24 a for setting the inspection target lens 25 are formed through the lens support pallet 24. In this embodiment, a convex lens is used as the inspection target lens 25. Then, the X-direction moving stage 22 and the Y-direction moving stage 23 are moved and adjusted by the X-direction moving motor 26 and the Y-direction moving motor 27, whereby one inspection target lens 25 on the lens support pallet 24 is inspected. It is arranged to move to the position.

  As shown in FIGS. 1 to 3, a surface illumination panel 28 as a light source is provided at an adjustment mechanism 29 as an adjustment unit at a lower portion of the pallet receiving base 21 so as to be positioned below the inspection target lens 25 at the inspection position. Are arranged so as to be movable in the X, Y and Z directions. The adjustment mechanism 29 includes an X direction manual stage 30, a Y direction manual stage 31, and a Z direction manual stage 32. A light shielding plate 33 as a light shielding means is disposed on the surface illumination panel 28 so as to be positioned between the surface illumination panel 28 and the inspection target lens 25 at the inspection position. A pinhole 34 is formed at the center of the upper surface of the light shielding plate 33 to partially shield the light from the surface illumination panel 28 and emit light as a point light source. The diameter of the pinhole 34 is set within a range of 50 to 1000 μm.

  Then, by manually adjusting the X-direction manual stage 30 and the Y-direction manual stage 31 and moving the surface illumination panel 28 and the light shielding plate 33 in the X direction and the Y direction, as shown in FIG. The peripheral portion including the entire edge portion of the pinhole 34, that is, the bright / dark boundary portion, is arranged on the optical axis OA of the inspection target lens 25. In this state, the Z-direction manual stage 32 is manually adjusted, and the surface illumination panel 28 and the light shielding plate 33 are moved in the Z direction, so that the light / dark boundary portion including the entire edge of the pinhole 34 of the light shielding plate 33 is included. Is arranged at the position of the focal length FD of the inspection target lens 25. The focal length is allowed to be shifted to some extent (usually about 200 μm at maximum). Thereby, based on the light emission from the pinhole 34 of the light shielding plate 33, parallel light that is substantially parallel is generated from the inspection target lens 25.

  As shown in FIG. 1 and FIG. 2, an image pickup means is provided above the lens support pallet 24 so as to be positioned on the upper side opposite to the light shielding plate 33 on the optical axis OA of the inspection target lens 25 at the inspection position. An imaging lens 35 and a CCD (solid-state imaging device) camera 36 are arranged so as to be movable and adjustable in the Z direction via a Z direction adjusting stage 37. Then, by manually adjusting the Z direction adjustment stage 37 and moving the imaging lens 35 and the CCD camera 36 in the Z direction, the focusing of the imaging lens 35 is adjusted so as to match the position of the inspection target lens 25. In this state, parallel light from the inspection target lens 25 enters the CCD camera 36 via the imaging lens 35, and an image of the light / dark boundary portion including the pinhole 34 and the peripheral portion including the entire peripheral edge portion thereof is the inspection target lens 25. Due to this lens action, a substantially uniform gray image is picked up.

  The CCD camera is connected to a computer 38 for processing an image via an image input port 39. The computer 38 is connected to a monitor / display 40 for displaying images. The gray image picked up by the CCD camera 36 is image-processed by the computer 38 and displayed on the monitor / display 40.

Next, an inspection method for inspecting the appearance of a lens using the lens inspection apparatus configured as described above will be described.
When a lens manufactured in the manufacturing process is inspected by this lens inspection apparatus, a plurality of inspection target lenses 25 are set in the set holes 24a of the lens support pallet 24, and the lens support pallet 24 is received by the pallet holder. Mount on the base 21. In this state, the X-direction moving stage 22 and the Y-direction moving stage 23 are moved and adjusted, and one inspection target lens 25 on the lens support pallet 24 is moved to the inspection position. In this state, the X-direction moving stage 22, the Y-direction moving stage 23, the X-direction manual stage 30 and the Y-direction manual stage 31 are moved and adjusted so that the pinhole 34 of the light shielding plate 33, the imaging lens 35 and the center of the CCD camera 36 are obtained. Is adjusted to be positioned on the optical axis OA of the inspection target lens 25.

  Thereafter, the Z direction adjustment stage 37 is manually adjusted, and the imaging lens 35 and the CCD camera 36 are moved in the Z direction so that the focus of the imaging lens 35 is adjusted to the position of the inspection target lens 25. In this state, the Z-direction manual stage 32 is manually adjusted to move the surface illumination panel 28 and the light shielding plate 33 in the Z direction, so that the pinhole 34 on the light shielding plate 33 is positioned at the focal length FD of the inspection target lens 25. Adjust to be placed. In this way, light emitted from the pinhole 34 of the light shielding plate 33 generates substantially parallel light from the inspection target lens 25, and the image of the pinhole 34 and the light / dark boundary portion of the entire peripheral edge of the inspection target lens 25. The CCD camera 36 picks up a substantially uniform gray image by the lens action. As described above, if the Z-direction manual stage 32 is manually adjusted so that the image displayed on the monitor display 40 spreads as a uniform gray image, the pinhole 34 is positioned at the focal length FD of the inspection target lens 25. Can be placed nearby.

  If the inspection target lens 25 has any defect, a partial image change appears in the gray image. That is, when the inspection target lens 25 has a light-shielding defect such as a scratch or a stain, the image of the defective part is taken in a dark state. In addition, when the inspection target lens 25 has a defect having optical distortion such as a pulse, the image of the defective part is captured in a state where the image is changed to light and dark by the lens action. Then, the captured image is processed in the computer 38 to determine the presence or absence of a defect in the inspection target lens 25, and when a defect occurs, it is fed back to the lens molding process as necessary. Control is performed to change the cooling time of the lens after molding.

  As described above, after the inspection of one inspection target lens 25 is finished, the X-direction moving stage 22 and the Y-direction moving stage 23 are moved and adjusted, and another inspection target lens 25 on the lens support pallet 24 is set to the inspection position. Move to place. The inspection target lens 25 can be inspected in the same procedure as described above. At this time, when the plurality of inspection target lenses 25 set in the set holes 24a of the lens support pallet 24 are the same lens, the inspection of the plurality of inspection target lenses 25 can be sequentially performed.

  As described above, in this lens inspection apparatus, substantially parallel light is generated from the inspection target lens 25 based on the point light source-like light emission from the pinhole 34, and the light / dark boundary portion including the pinhole 34 and its edge portion. These images are picked up by the CCD camera 36 as a substantially uniform gray image by the lens action of the inspection object lens 25. Therefore, when the inspection target lens 25 has defects such as scratches, dirt, and pulse, a partial image change appears as a light / dark change in the gray image. Accordingly, it is possible to clearly detect various defects relating to the lens including defects having optical distortion.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with a focus on differences from the first embodiment.
In the second embodiment, as shown in FIGS. 4 and 5, instead of the light shielding plate 33 having the pinhole 34 of the first embodiment, a light shielding means is provided at the center of the upper surface of the surface illumination panel 28. A black spot 43 is provided. The diameter of the black spot 43 is set within a range of 50 to 1000 μm, similar to the diameter of the pinhole 34 of the first embodiment. Then, the inspection target lens 25 is inspected in a state where the black dot 43 and the peripheral portion including the entire peripheral edge thereof are adjusted and arranged on the optical axis OA of the inspection target lens 25 at the position of the focal length FD of the inspection target lens 25. It is like that.

  Therefore, also in the second embodiment, as in the case of the first embodiment, the images of the black spots 43 and the light / dark boundary portions of the entire peripheral edge thereof are made to be substantially uniform gray by the lens action of the inspection object lens 25. An image is taken by the CCD camera 36 as an image. Therefore, various defects such as scratches, dirt, and pulse related to the lens can be clearly detected.

(Third embodiment)
Next, a third embodiment of the present invention will be described with a focus on differences from the respective embodiments.
In the third embodiment, as shown in FIG. 6, a slit 44 is formed at the center of the light shielding plate 33 instead of the pinhole 34 of the first embodiment. Then, the inspection target lens 25 is inspected in a state in which the bright / dark boundary portion of the edge of the slit 44 is adjusted and arranged at the position of the focal length FD of the inspection target lens 25 on the optical axis OA of the inspection target lens 25. It has become.

  Accordingly, also in the third embodiment, the image of the bright / dark boundary portion at the edge of the slit 44 is converted into a CCD image as a substantially uniform gray image by the lens action of the lens to be inspected 25, as in the case of the above embodiments. Images are taken by the camera 36. Therefore, various defects such as scratches, dirt, and pulse related to the lens can be clearly detected.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with a focus on differences from the respective embodiments.
In the fourth embodiment, as shown in FIG. 7, a black line 45 as a light shielding means is provided at the center of the upper surface of the surface illumination panel 28 instead of the black spot 43 in the second embodiment. Then, the inspection target lens 25 is inspected in a state in which the light / dark boundary portion of the edge of the black line 45 is adjusted and arranged on the optical axis OA of the inspection target lens 25 at the position of the focal length FD of the inspection target lens 25. It has become.

  Accordingly, also in the fourth embodiment, the image of the bright / dark boundary portion at the edge of the black line 45 is converted into a substantially uniform gray image by the lens action of the inspection object lens 25, as in the case of each of the embodiments. The image is picked up by the CCD camera 36. Therefore, various defects relating to the lens can be clearly detected.

(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described with a focus on differences from the respective embodiments.
In the fifth embodiment, as shown in FIG. 8, a light shielding plate 33 having no pinhole 34 is provided in place of the light shielding plate 33 having the pinhole 34 of the first embodiment. Then, the inspection target lens 25 is inspected in a state where the light / dark boundary portion of the edge portion 33a of the light shielding plate 33 is adjusted and arranged on the optical axis OA of the inspection target lens 25 at the position of the focal length FD of the inspection target lens 25. To do.

  Accordingly, also in the fifth embodiment, as in the case of each of the embodiments described above, the image of the light / dark boundary portion of the edge portion of the edge portion 33a is substantially uniform gray image due to the lens action of the inspection object lens 25. As shown in FIG. Therefore, various defects relating to the lens can be clearly detected.

(Sixth embodiment)
Next, a sixth embodiment of the present invention will be described with a focus on differences from the respective embodiments.
Now, in the sixth embodiment, as shown in FIGS. 9 and 10, a grid plate 46 as a light shielding means is provided instead of the light shielding plate 33 having the pinhole 34 of the first embodiment. . In the grid plate 46, a plurality of slit-like light-transmitting portions 46a and a plurality of narrow-width light-shielding portions 46b are alternately formed. Then, in the state where the boundary portion between the light transmitting portion 46a and the light shielding portion 46b of the grid plate 46 is adjusted and arranged on the optical axis OA of the inspection target lens 25 at the position of the focal length FD of the inspection target lens 25, 25 inspections are performed.

  Accordingly, also in the sixth embodiment, the image of the boundary portion (brightness / darkness boundary portion) between the light transmitting portion 46a and the light shielding portion 46b is caused by the lens action of the inspection target lens 25 in substantially the same manner as in the above embodiments. The image is picked up by the CCD camera 36 as a substantially uniform gray image. Therefore, various defects relating to the lens can be clearly detected.

(Seventh embodiment)
Next, a seventh embodiment of the present invention will be described with a focus on differences from the respective embodiments.
In the seventh embodiment, as shown in FIG. 11, the inspection target lens 25 is a concave lens. A convex lens 47 is disposed close to the light shielding plate 33 on the optical axis of the inspection target lens 25 so as to be positioned on the optical axis OA of the inspection target lens 25. The convex lens 47 corrects parallel light traveling toward the imaging lens 35.

  Therefore, also in the seventh embodiment, parallel light is generated from the inspection target lens 25 to the imaging lens 35 in substantially the same manner as in the above embodiments, and a uniform gray image is captured at the light / dark boundary portion. Thus, various defects relating to the lens can be clearly detected.

(Example of change)
In addition, each said embodiment can also be changed and actualized as follows.
In the seventh embodiment, the configurations of the second to sixth embodiments are used as light shielding means.

  In FIG. 1, the lens support pallet 24 is moved and the plurality of inspection target lenses 25 are sequentially inspected, but conversely, the imaging lens 35 and the light source are connected to the lens support pallet 24. It is configured to move and inspect a plurality of inspection target lenses 25.

(Another technical idea)
Furthermore, the technical idea grasped | ascertained by the said embodiment is described below.
(B) The light shielding means comprises a light shielding plate having a pinhole or a slit, and a light / dark boundary portion of an edge of the pinhole or slit is disposed on the optical axis of the lens to be inspected. Or the lens inspection apparatus of 2.

  Therefore, by adjusting and arranging the light / dark boundary portion of the pinhole or slit of the light shielding plate on the optical axis of the lens to be inspected and in the vicinity of the position of the focal length of the lens to be inspected, substantially parallel light is generated from the lens to be inspected. A substantially uniform gray image can be obtained.

  (B) The light shielding means is a black spot or a black line, and a light / dark boundary part of the edge of the black spot or black line is disposed on the optical axis of the lens to be inspected. The lens inspection apparatus according to any one of the items (a).

  Therefore, by adjusting and arranging the bright and dark boundary portion of the edge of the black point or black line on the optical axis of the inspection target lens near the focal length position of the inspection target lens, substantially parallel light is generated from the inspection target lens. A substantially uniform gray image can be obtained.

  (C) In the case where the lens to be inspected is a concave lens, a convex lens is disposed on the optical axis of the concave lens in order to obtain parallel light directed to the imaging means. The lens inspection device according to any one of (a) and (b).

Therefore, when the inspection target lens is a concave lens, substantially parallel light can be generated with respect to the imaging means, and the concave lens can be inspected appropriately.
(D) The light shielding means comprises a light shielding plate, and an edge portion of the light shielding plate is disposed on the optical axis of the lens to be inspected. The lens inspection device according to any one of items (c) to (c).

  (E) The light shielding means is formed of a grid plate, and a boundary portion between the light transmitting portion and the light shielding portion of the grid plate is disposed on the optical axis of the lens to be inspected. The lens inspection apparatus according to any one of the technical ideas (a) to (d).

  (F) Inspecting the appearance of the inspection target lens by causing the light from the light / dark boundary portion to reach the inspection target lens, generating substantially parallel light from the inspection target lens, and imaging the parallel light by the imaging means. A lens inspection method characterized by the above.

  Therefore, the same effect as that described in claim 1 can be obtained.

The perspective view which shows the lens inspection apparatus of 1st Embodiment. The principal part expanded sectional view of the lens inspection apparatus of FIG. The perspective view which expands and shows the light-shielding plate of the lens inspection apparatus of FIG. The principal part front view which shows the lens inspection apparatus of 2nd Embodiment. The perspective view which shows the surface illumination panel of the lens inspection apparatus of FIG. The perspective view which shows the light-shielding plate of the lens inspection apparatus of 3rd Embodiment. The perspective view which shows the surface illumination panel of the lens inspection apparatus of 4th Embodiment. The principal part sectional view showing the lens inspection device of a 5th embodiment. The principal part sectional view showing the lens inspection device of a 6th embodiment. The perspective view which shows the grid board of the lens inspection apparatus of FIG. The principal part sectional view showing the lens inspection device of a 7th embodiment.

Explanation of symbols

  24 ... Lens support pallet, 25 ... Lens to be inspected, 28 ... Surface illumination panel as light source, 29 ... Adjustment mechanism as adjustment means, 32 ... Z direction manual stage, 33 ... Light shielding plate as light shielding means, 34 ... Pinhole 35 ... Imaging lens constituting imaging means, 36 ... CCD camera constituting imaging means, 38 ... Computer, 40 ... Monitor display, 43 ... Black spot as light shielding means, 44 ... Slit, 45 ... Black as light shielding means Line 46, Grid plate as light shielding means, 46a ... Translucent portion, 46b ... Light shielding portion, 47 ... Convex lens, OA ... Optical axis, FD ... Focal length.

Claims (2)

A light source is arranged on one side in the optical axis direction of the inspection target lens, and an imaging unit is arranged on the other side, so that light from the light source is generated as almost parallel light to the imaging unit side through the inspection target lens. In addition, an adjusting means for adjusting the position in the optical axis direction is provided, and a light shielding means for shielding a part of the light from the light source is arranged so that the imaging means can image a bright / dark boundary portion. Lens inspection device characterized by. The lens inspection apparatus according to claim 1, wherein the light shielding unit is disposed on a light source.

Images