JPH0571732U - Lighting aids - Google Patents

Abstract

(57) [Abstract] [Purpose] Attach to a lighting device to set lighting conditions with a large aperture ratio and close to actual conditions. A diffuser plate 1 having an effective diameter that diffuses light emitted from an illuminating device 5 and has a predetermined aperture ratio with respect to at least a distance to a sample 6 to be tested, and a diaphragm 2 having the effective diameter in the vicinity thereof.
Are installed between the illuminating device 5 and the test sample 6 irradiated with the light emitted from the illuminating device 5.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an illumination auxiliary device, and more particularly to an illumination auxiliary device used for illuminating an apparatus for inspecting a variation in charge accumulation of a CCD solid-state image pickup device.

[0002]

[Prior Art]

 Conventionally, the charge storage capacity of each pixel of a CCD solid-state image sensor (hereinafter simply referred to as CCD) varies during the manufacturing process, and only the charge storage capacity of which the variation between pixels is within a predetermined range is a non-defective product. Shipped as. In order to inspect this variation, the CCD was illuminated with light with a uniform irradiation intensity, that is, without unevenness, and the charge output from each pixel was measured and compared with each other. For this type of inspection, a telecentric illumination device that can emit uniform light has been developed. Illumination devices of this type include, for example, a type with an aperture ratio of F10 and a pupil position at infinity, and a type with an aperture ratio of F3 and a pupil position of 200 mm.

By the way, in recent years, a camera-integrated movie in which the CCD is built in as a light-receiving portion has been remarkably reduced in size and weight. Conventionally, a large number of F10 and F5.6 cameras having a relatively large F value have been widely used. Such a camera lens having a large F value, that is, a small aperture ratio, has a small incident angle of the light radiated to the CCD at the time of use. Was reached. For example, a 1/2 inch CCD is a 4.8 mm × 6.4 mm rectangle, and in the above-described F10 lighting device, the variation in the irradiation intensity of the irradiation light in this area is within ± 0.5%. is there.

Further, in this type of camera lens, the distance from the image point to the exit pupil of the optical system is set to be relatively large, from infinity to about 50 mm. For this reason, even if the distance to the pupil of the optical system of the illumination device used for the conventional CCD variation inspection is infinite, it was sufficiently suitable for the inspection purpose.

By the way, a lens having a brightness of about F1.2 has been adopted as a camera lens. FIG. 8 is an explanatory diagram showing the relationship between the aperture ratio of the camera lens and the maximum incident angle. A light beam incident on the lens L0 from a subject (not shown) forms an image on the CCD 9. If the maximum incident angle at this time is θ, and a camera lens with the aperture ratio of F10 is set to F1.2 when the pupil position of the camera is set to the same, the CCD 9 at that time is Maximum incident angle of incident light θ₁And θ₂Is θ ₁ = 2.86 ° and θ₂= 22.6 °. That is, when the camera lens of F1.2 is adopted, the light beam enters the CCD at an incident angle about 10 times larger than that of the case of F10. If the distance of the pupil position at this time is 40 mm, the effective diameter of the lens L0 is φ4 mm for F10, while that of F1.2 requires a lens having a large aperture of at least φ33 mm.

In addition, in order to realize the downsizing and weight saving of the recent camera-integrated movies, the camera lens must be downsized. The following methods can be considered to reduce the size of the camera lens. (1) Reduce the CCD size. (2) Shorten the distance from the exit pupil position of the camera lens to the CCD (increase the principal ray tilt angle μ).

First, in the above (1), the microlens array is mounted on the CCD surface in order to increase the amount of light received by each pixel of the small CCD in order to downsize the camera lens without deteriorating the imaging performance. The one attached to is commercialized. FIG. 9 is a sectional view showing an example of the CCD with the microlens array. The CCD 9 has a photodiode 12 formed on a silicon substrate 10 and a microlens 11 made of resin arranged on the photodiode 12. In this CCD 9, the light beam 13 passes through the microlens 11 and enters the fort diode 12. The size of one pixel is 9.9 μm × 8.7 μm for a CCD with a nominal size of 1/2 inch and 410,000 pixels. However, the shape of the microlens 11 is not always exactly the same, and the position of the microlens is not necessarily formed at a precisely fixed position for each pixel. Therefore, when the incident angle of the light incident on the light receiving surface of the CCD 9 changes, the ratio of the charge storage amount for each pixel to the light receiving amount changes, and the change is not constant for each pixel. It is known that the ratio of the charge accumulation amount for each pixel relatively varies depending on the incident angle of the incident light.

Therefore, as described above, in the case of a CCD in which the maximum incident angle θ with respect to the CCD 9 becomes larger than that of the conventional one, which is judged to be defective by inspection, there is a variation in the charge accumulation amount for each pixel depending on the incident angle. It began to appear big. Therefore, it is most desirable to irradiate the CCD with the irradiation light having the same incident angle as that in the state in which the CCD is actually used, and the illuminating device having a large maximum aperture ratio is required.

Next, in (2), the exit pupil position of the camera lens when a small single-plate CCD is used is commercialized up to 20 mm from the CCD. As shown in FIG. 10, the image formation state of the principal ray on the CCD when the distance from the exit pupil position of the camera lens to the CCD is shortened in this way.

In FIG. 10, light rays incident on a camera lens from a subject (not shown) are imaged on CCD 1 and CCD 2 shown in FIGS. At this time, the CCD 1 has a 2/3 inch size and the CCD 2 has a 1/2 inch size. At this time, the distances from the image point, that is, the CCD surface to the exit pupil are A ₁ = 50 mm and A ₂ = 25 mm, respectively, and the maximum inclination angle of the chief ray at the CCD edge is μ ₁ = 6.28 °, μ ₂ = 9.09 °. As described above, when the CCD of this size is actually mounted and the distance from the exit pupil position of the camera lens to the CCD is shortened, the photoelectric conversion property of CCD when the principal ray tilt angle μ becomes large is grasped. There is a need.

[0011]

[Problems to be solved by the device]

 In the inspection of the CCD described above, it is necessary to increase the maximum aperture ratio of the optical system of the illumination device in order to perform the inspection with a large incident angle such as a camera lens of F1.2. As explained in the comparison with the effective diameter of the camera lens of F10, it is necessary to use a lens with a large diameter in the optical system of the illumination device. However, a lens with a large diameter requires high processing accuracy, and an auxiliary optical system must be added to generate uniform light that passes through the lens. Overall it will be very expensive. Even if there is an illuminating device that can emit telecentric light with a large aperture ratio of about F1.2, that ray is irradiated to the CCD to be inspected, and the tilt angle μ of the principal ray reaching the CCD by the actual camera is It is not preferable to judge the performance of CCD with respect to a light beam having a wide beam width with such a large incident angle.

On the other hand, an illuminating device that can emit uniform light having a uniform intensity distribution and has an optical system with a small aperture ratio is relatively inexpensive and is widely used. Therefore, it is a user's request to irradiate a uniform light from this type of illuminating device as a light flux with a large incident angle over a predetermined range of a test sample such as CCD.

Further, when the distance from the exit pupil position of the camera lens to the CCD is shortened, the principal ray tilt angle is greatly inclined and the light enters, so that a thin light flux such as F10 or F5.6 causes a positional deviation. It was found that when incident on a CCD with a microlens attached, the amount of accumulated charge remarkably varied due to the displacement of the microlens at the outer peripheral edge of the CCD. Further, since this phenomenon is not so remarkable in a lens such as F1.2 having a wide light flux, there is a problem that a defect cannot be discriminated by inspection in an illumination device having a large aperture ratio as described above.

Therefore, an object of the present invention is to solve the problems of the above-mentioned conventional techniques, and even with a conventional illumination device having a small aperture ratio, there is no unevenness through an optical system having a large aperture ratio. It is possible to irradiate the test sample with a uniform irradiation light beam, and also to irradiate the test sample with a uniform irradiation light beam from the same position as the pupil distance of the optical system actually used. Another object of the present invention is to provide a lighting assistance device.

[0015]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, a first invention is arranged in an optical path between an illuminating device and a sample to be irradiated with light emitted from the illuminating device, and diffuses light emitted from the illuminating device. It is characterized by comprising a diffuser plate and a diaphragm arranged in the optical path in the vicinity of the diffuser plate and having an effective diameter that provides a predetermined aperture ratio with respect to the distance to the sample to be tested. ..

A second invention is a diffuser plate which is installed in an optical path between a lighting device and a test sample irradiated by light emitted from the lighting device and which diffuses light emitted from the lighting device. And an aperture stop disposed in the vicinity of the diffuser plate in the optical path and at a predetermined pupil position, and having an effective diameter that provides a predetermined aperture ratio with respect to the distance between the pupil position and the test sample. It is characterized by that.

In the case described above, it is preferable that a correction filter for correcting the intensity distribution of the diffused light from the diffuser plate is provided.

Further, it is preferable to include lens means for diverging the light flux from the illumination device so that the light flux irradiates the entire range within the effective diameter of the diffusion plate.

Further, it is preferable that the diffuser plate and the diaphragm are arranged at predetermined positions in an adapter that can be attached to and detached from the lighting device.

[0020]

[Action]

 According to the first invention, a diffusing plate for diffusing the light emitted from the lighting device is arranged in the optical path between the lighting device and the test sample irradiated by the light emitted from the lighting device. In the vicinity of the diffuser plate in the optical path, a diaphragm having an effective diameter that gives a predetermined aperture ratio with respect to the distance to the sample to be inspected is arranged. A large aperture ratio can be set by applying such a configuration to the illuminator, and a large incident angle with respect to a predetermined range of the test sample can be set by the diffusion action at each diffusion point of the diffusion plate arranged in the optical path. It is possible to irradiate the sample surface with the inspection light evenly, and it is possible to perform the inspection under the same conditions as the brightness of the optical system that actually incorporates the CCD.

According to the second invention, a diffusing plate for diffusing the light emitted from the illuminating device is provided in the optical path between the illuminating device and the test sample irradiated with the light emitted from the illuminating device. Since, in the vicinity of the diffuser plate in the optical path and at a predetermined pupil position, an aperture having an effective diameter that has a predetermined aperture ratio with respect to the distance between the pupil position and the sample to be tested is arranged. A secondary light source with a predetermined aperture ratio can be placed at the same pupil position as the camera lens actually installed, and the test light with a large principal ray tilt angle can be emitted from that position to the test sample. It can be inspected under the same conditions as when it is installed.

In the above-mentioned case, by using the correction filter, it is possible to suppress the transmission of the light rays in the vicinity of the optical axis to reduce the light, correct the dispersion of the diffused light from the diffuser plate, and obtain a uniform light flux. You can

Further, by providing lens means for diverging the light beam bundle, the light beam bundle from the lighting device can irradiate the entire range within the effective diameter of the diffusion plate.

Further, since the diffuser plate and the diaphragm are arranged at predetermined positions in the adapter which is attachable / detachable to / from the illumination device, various pupil positions and a diaphragm having a predetermined aperture ratio can be combined. It can be used with various camera lenses.

[0025]

【Example】

 Hereinafter, a first embodiment of the lighting assistance device according to the first invention will be described with reference to FIG. FIG. 1 is a sectional view of the first embodiment. In the figure, reference numeral 5 indicates an outgoing light section of the illuminating device, and the illuminating device 5 is composed of an illumination optical system having a filament as a light-emitting body, and is designed to emit uniform and uniform illumination light. Has been done. The aperture ratio is designed to be F10. The variation in the illumination brightness of the illumination light is ± 0.5% or less in the case of a rectangular area of 6.4 mm × 4.8 mm for a nominal 1/2 inch CCD with 410,000 pixels. Is required, and is suppressed to ± 1.5% or less in a rectangular area of 1.5 mm × 1.5 mm.

An intermediate tube 7 is fitted to the tip of the emitted light portion 5 a of the illuminating device 5, and is held by a mounting screw 8 provided on the side surface so as not to fall off. A lens system 4 is housed inside the intermediate cylinder 7. The lens system 4 is an optical system including one concave lens L1 and one convex lens L2. The light beam from the convex lens L3 of the illuminating device 5 is diverged by the concave lens L1 and then converged by the convex lens L2 to illuminate the entire effective range of the diffusion plate 1.

Further, a cylindrical adapter 20 having a substantially truncated cone shape is detachably fitted to the lower end of the intermediate cylinder 7, and is held by a mounting screw 21 so as not to fall off. Inside the adapter 20, a diffuser plate 1 and a diaphragm 2 which are closely attached to each other are fitted in a mounting groove 20a formed on the inner peripheral surface of the adapter. Further, the filter 3 is similarly fitted to the lower end of the adapter in a mounting groove 20b formed on the inner peripheral surface of the adapter.

The diffuser plate 1 is made of a circular opalescent acrylic plate having a thickness of about 2.0 mm, and diffuses the light rays passing therethrough by diffusely reflecting it inside. Therefore, the light beam bundle that has passed through the lens system 4 and has entered the diffusion plate 1 is diffused and transmitted in each direction in the diffusion plate 1. The intensity distribution of the diffused light at this time is the strongest in the incident direction of the incident light and sharply decreases in the direction inclined to the incident direction. Theoretically, according to the law of cosine squares, if the tilt angle is μ, the intensity distribution is proportional to cos ⁴ μ. Strictly speaking, the diffuser plate 1 having such a configuration does not form a light source as a perfect diffusing surface and its area is large, so that the incident direction of incident light is not constant and the actual intensity distribution is more complicated. However, it tends to be strongest in the optical axis direction and weak in the peripheral direction.

The diaphragm 2 is a circular diaphragm provided in close contact with the lower surface of the diffusion plate 1. The emission range of the light diffused in the diffuser plate 1 is limited by the diaphragm 2, and thus the diffuser plate 1 functions as a secondary light source having the aperture of the diaphragm 2. In this embodiment, the aperture diameter is variable, and when the aperture diameter is set to 33 mm and the distance between the diffusion plate 1 and the sample surface 6a of the sample 6 is set to 40 mm, the aperture ratio is F1.2. Become. It is also possible to set the distance smaller and increase the aperture ratio.

The filter 3 is an N D filter that corrects the intensity distribution of the light flux that has passed through the diaphragm 2 to make it uniform. In this embodiment, the adapter 20 is provided so as to be closer to the sample surface 6a than the diffuser plate 1 in order to satisfactorily correct the intensity distribution and reduce the size of the entire adapter 20.

As described above, the intensity distribution of the light flux from the diffuser plate 1 approximately follows the cosine square law, and therefore is the strongest in the optical axis direction and weakens in the peripheral direction. Therefore, the density of the filter 3 is manufactured to be the highest in the vicinity of the central optical axis as shown in the filter density distribution chart shown in FIG. 4 and to be lighter in the peripheral direction. This makes it possible to correct the intensity distribution of light rays to make them uniform.

The sample 6 is placed on a stage (not shown), and the sample surface 6a is illuminated with light whose intensity distribution is uniformly corrected. In this embodiment, the sample 6 is an interline CCD with a nominal size of 1/2 inch and 410,000 pixels, and the size is a rectangle of 6.4 mm × 4.8 mm, and the size of one pixel is 9.9 μm ×. It is 8.7 μm.

The variation in the intensity distribution of the light with which the sample 6 is irradiated can be suppressed to ± 1.5% in the rectangular range of 6.4 mm × 4.8 mm, so that the illumination can be sufficiently performed without using the filter 3. A uniform ray bundle can be realized. Therefore, in the above-mentioned configuration, the effect can be obtained even if the filter 3 is excluded, as long as it is within the inspection range in which the predetermined variation in the light intensity can be allowed.

FIG. 2 shows an illumination assisting device having a structure in which the adapter 20 is omitted as a modification of the first embodiment described above. In this modified example, the tip portion of the convex lens L2 of the intermediate cylinder 7 is extended so as to have a slightly smaller diameter, and the diffusion plate 1, the diaphragm 2 and the filter 3 are housed therein, and the same effect as that of the above-described embodiment is obtained. I got it. By doing so, the number of parts can be omitted when a predetermined F value is determined, and the like, so that an inexpensive integrated device can be provided.

Next, referring to FIG. 3, a first embodiment of the second invention will be described. In the figure, the same intermediate tube 7 is attached to the same illuminating device 5 as in the first invention described above. That is, the intermediate cylinder 7 is fitted to the tip of the emitted light portion 5a of the illuminating device 5, and is held by the mounting screw 8 provided on the side surface so as not to fall off. A lens system 4 is housed inside the intermediate cylinder 7, and the lens system 4 is an optical system including one concave lens L1 and one convex lens L2. The light beam from the convex lens L3 of the illuminating device 5 is diverged by the concave lens L1 and then converged by the convex lens L2 to illuminate the entire effective range of the diffuser plate 1.

Further, a cylindrical adapter 20 having the same truncated cone shape as that of the first invention described above is detachably fitted to the lower end of the intermediate cylinder 7 and is retained by a mounting screw 21 so as not to fall off. .. Inside the adapter 20, a diffuser plate 1 and a diaphragm 2 which are closely attached to each other are fitted in a mounting groove 20a formed on the inner peripheral surface of the adapter. Further, the filter 3 is similarly fitted to the lower end of the adapter in a mounting groove 20b formed on the inner peripheral surface of the adapter.

The diffuser plate 1 is made of a circular opal white acrylic plate having a thickness of about 2.0 mm, and diffuses the light rays passing therethrough by diffusely reflecting it inside. The mounting position of the diffuser plate 1 is set so as to coincide with the exit pupil position of the optical system when the CCD 6 to be inspected is mounted on the camera.

The diaphragm 2 is a circular diaphragm provided in close contact with the lower surface of the diffusion plate 1. The diaphragm 2 limits the emission range of the light diffused in the diffuser plate 1, and thus the diffuser plate 1 functions as a secondary light source having the aperture of the diaphragm 2. In this embodiment, it is set to F10. At this time, since the distance between the pupil position and the CCD 6 is set to 25 mm, the diaphragm 2 is narrowed to an effective diameter of 2.5 mm.

The filter 3 is an ND filter used for the same purpose as the above-mentioned filter. Also in the present invention, it is provided at the lower end of the adapter 20 so as to be closer to the sample surface 6a than the diffusion plate 1.

FIG. 4 shows an example in which the pupil position and the F value are set and attached to the adapter 20. In the same figure (a), an adapter 20 having a pupil position of 20 mm and an F value of 5.6 is shown, and the effective diameter of the diaphragm 2 at this time is 3.6 mm. Similarly, the same figure (b) shows the adapter 20 in which the pupil position is 30 mm and the F value is 5.6, and the effective diameter of the diaphragm 2 at this time is 5, 35 mm. By simply selecting these adapters 20 and mounting them on the tip of the above-mentioned intermediate cylinder 7, it is possible to create an illuminated state for inspection corresponding to various optical systems. Further, it is clear that the adapter 20 can also realize an illumination assisting device corresponding to F1.2 as shown in FIG. 1, and the illumination assisting device and the pupil according to the first invention for performing the above-described inspection with an emphasis on the incident angle. The illumination assisting device according to the second invention for performing position-oriented inspection can be easily switched by replacing the adapter 20. Furthermore, it is also preferable to prepare various adapters other than these combinations according to the inspection target.

FIG. 5 and FIG. 6 show that in the first and second inventions, uniform light without unevenness can be emitted from the illumination device 5 having a small aperture ratio at a large emission angle, and a divergence optical system is required in the middle. It shows a modified example in which the entire effective range of the diaphragm 2 can be irradiated without the irradiation. Since the light flux of this kind can be directly applied to the diffusion plate 1, it is not necessary to provide the lens system 4 in the intermediate cylinder 7. Therefore, it suffices to attach the intermediate tube 7 for extending the optical path of a predetermined length to the illuminating device 5 and further attach the adapter 20 to the tip thereof.

FIG. 5 shows an illumination assisting device in which the intermediate cylinder 7 without the lens system 4 is used and the adapter 20 shown in FIG. FIG. 6 shows an example of the integral type intermediate cylinder 7 which does not use the adapter of the first invention shown in FIG. As described above, it is understood that the presence or absence of the lens system 4 depends on the illuminating device, and the selection of the adapter in the illumination auxiliary device can be performed regardless of the lens system 4.

Although the diffuser plate 1 and the diaphragm 2 are configured to be in close contact with each other in the embodiment of the invention described above, a predetermined aperture ratio is ensured even if the diaphragm 2 is arranged separately from the diffuser plate 1. It is good if possible, but it is not always necessary to bring them together. The advantages of the close contact are that the diffuser plate and the diaphragm can be handled as a single unit, the assembly work can be simplified, and the optical distances can be easily set in terms of design. Further, even if the positions of the diffuser plate 1 and the diaphragm 2 are oppositely arranged on the optical path, there is no problem as long as a predetermined aperture ratio or pupil position is secured. For example, the diffuser plate 1 may be arranged at a predetermined pupil position and the diaphragm 2 having a predetermined aperture ratio may be closely attached to the upper surface of the diffuser plate 1. In this case, the light beam from the illuminating device is focused by the diaphragm 2 into light having a predetermined aperture ratio, and then is irradiated onto the sample surface 6a as light diffused at the pupil position by the diffuser plate 1. Further, although the milky acrylic plate is used for the diffusing plate in this embodiment, various diffusing plates may be used as long as they are optical members such as a glass plate having a diffusing surface formed on the surface thereof and capable of obtaining a predetermined diffusing coefficient. It can be used to set a predetermined thickness.

In each of the above-described embodiments, it has been described that the filter 3 may be used or the filter 3 may not be attached depending on the allowable range thereof, but the intensity distribution of the light beam through the diffusion plate is obtained in advance. It is also possible to correct the charge output of the CCD by the correction circuit of the control unit in the inspection device, convert it into data that does not depend on the intensity distribution, and inspect the CCD for quality based on the result.

[0045]

[Effect of the device]

 As described above, according to the first and second inventions described above, it is possible to realize a light beam under the same conditions as when the sample to be tested is actually incorporated in the apparatus by a simple device, and it is required. This has the effect of performing an inspection closer to the specified specifications.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment according to the first invention.

FIG. 2 is a sectional view showing a modification of the embodiment shown in FIG.

FIG. 3 is a sectional view showing a first embodiment according to a second invention.

FIG. 4 is a sectional view showing an example of an adapter used in the first and second inventions.

FIG. 5 is a sectional view showing a second embodiment according to the second invention.

FIG. 6 is a sectional view showing a second embodiment according to the first invention.

FIG. 7 is a characteristic diagram showing a density distribution of a filter.

FIG. 8 is a ray diagram showing a relationship between a pupil position distance of a camera lens and a chief ray tilt angle.

FIG. 9 is a ray diagram showing the relationship between the aperture ratio of a camera lens and the maximum incident angle.

FIG. 10 is a sectional view of a CCD provided with a microlens.

[Explanation of symbols]

 1 Diffusion plate 2 Aperture 3 Filter 4 Lens system 5 Illuminator 6 Sample 7 Intermediate tube 8, 21 Mounting screw 20 Adapter L1 Concave lens L2 Convex lens L3 lens

Claims (5)

[Scope of utility model registration request] 1. A diffuser plate installed in an optical path between an illuminating device and a sample to be inspected irradiated with light emitted from the illuminating device, for diffusing light emitted from the illuminating device, and a diffusion plate in the optical path. An illumination assisting device, comprising: a diaphragm disposed near a diffuser plate and having a diaphragm having an effective diameter having a predetermined aperture ratio with respect to a distance to the sample to be tested. 2. A diffusion plate installed in an optical path between an illuminating device and a test sample irradiated by light emitted from the illuminating device, for diffusing light emitted from the illuminating device, and a diffusion plate in the optical path. An illumination assist characterized by comprising a diaphragm disposed in the vicinity of a diffuser plate and at a predetermined pupil position, and having a diaphragm having an effective diameter that has a predetermined aperture ratio with respect to the distance between the pupil position and the test sample. apparatus. 3. The illumination auxiliary device according to claim 1, further comprising a correction filter that corrects an intensity distribution of diffused light from the diffuser plate. 4. A lens means for diverging the light beam so that the light beam from the illuminating device irradiates the entire range within the effective diameter of the diffuser plate. 2. The lighting assistance device according to any one of 2. 5. The illumination according to claim 1, wherein the diffuser plate and the diaphragm are arranged at predetermined positions in an adapter that can be attached to and detached from the illumination device. Auxiliary device.