Inspection lighting device and inspection system

Abstract

To provide an inspection illumination device capable of imaging a whole periphery of side surface parts of a workpiece by once imaging so as to realize an excellent S / N ratio while having a simple configuration.SOLUTION: An inspection illumination device includes: a first irradiation optical path L11 for radiation of first inspection light to a first side surface part W1 of a workpiece W; and a first detection optical path L12 from the first side surface part W1 to an imaging mechanism 4. The device comprises: a first optical system 1 which allows the first inspection light to be radiated to the first side surface part W1 in a polarized state in a predetermined direction; and a second optical system 2 which includes a second irradiation optical path L21 for radiation of second inspection light to a second side surface part W2 of the workpiece, being the side surface part on the opposite side of the first side surface part W1, and a second detection optical path L22 from the second side surface part W2 to the imaging mechanism 4, and allows the second inspection light to be radiated to the second side surface part W2 in a state polarized in the same direction as the direction of the first inspection light. At least partial polarization components of the first inspection light and the second inspection light where a change occurs in polarization by reflection / dispersion in the workpiece W are made incident to the imaging mechanism 4, and also the light polarized in the predetermined direction is prevented from being made incident to the imaging mechanism 4.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an inspection illumination device for inspecting, for example, the side surface of a workpiece. [Background technology]

[0002] In visual inspections of workpieces such as tablets that are roughly flattened cylindrical, not only the flat and bottom surfaces of the workpieces but also the entire circumference of their side surfaces are inspected based on captured images. In the inspection system described in Patent Document 1, the tablet is held in a holding groove formed in a drum with approximately half of its side surface exposed and transported to the camera's imaging area. After imaging of one side surface is completed, the other side surface is held in another drum with the same structure with the other side surface exposed, and imaging is performed in the same manner. In other words, the tablet is held in a different direction and imaged twice, thereby obtaining an image of the entire circumference of the tablet.

[0003] However, such an inspection system requires a very complex mechanism and at least two cameras as the imaging mechanism. However, it is not possible to simultaneously image the entire periphery of the side surface. For this reason, it is difficult to reduce the time required to image the entire periphery of the side surface of the workpiece. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-74664 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in consideration of the above-mentioned problems, and aims to provide an inspection illumination device that has a simple configuration, is capable of capturing an image of the entire periphery of the side of a workpiece in a single image capture, and achieves a good S / N ratio. [Means for solving the problem]

[0006] That is, the inspection illumination device of the present invention comprises a first optical system having a first illumination optical path through which a first inspection light reaches a first side portion of a workpiece, and a first detection optical path from the first side portion to an imaging mechanism, and configured so that the first inspection light is irradiated onto the first side portion while being polarized in a predetermined direction; and a second optical system having a second illumination optical path through which a second inspection light reaches a second side portion of the workpiece that is opposite the first side portion, and a second detection optical path from the second side portion to the imaging mechanism, and configured so that the second inspection light is irradiated onto the second side portion while being polarized in the same direction as the first inspection light, and is characterized in that it is configured to cause at least some of the polarized components of the first inspection light and second inspection light that have been reflected or scattered by the workpiece and have undergone a change in polarization to be incident on the imaging mechanism, and to prevent light polarized in the predetermined direction from entering the imaging mechanism.

[0007] With this configuration, the first inspection light reflected or scattered by the first side surface portion and the second inspection light reflected or scattered by the second side surface portion can be simultaneously incident on the imaging mechanism, thereby enabling, for example, imaging of the entire circumference of the side surface of the workpiece at once. Furthermore, the passing light of the first inspection light that is not irradiated on the workpiece but enters the second optical system on the opposite side of the workpiece and travels along the second detection optical path toward the imaging mechanism can be prevented from entering the imaging mechanism. Similarly, the light of the second inspection light that is not irradiated on the workpiece but enters the first optical system on the opposite side of the workpiece can also be prevented from entering the imaging mechanism. Therefore, only the light that is a signal component reflected or scattered by the first and second side surface portions of the workpiece can be incident on the imaging mechanism, while the light that is a noise component that is not irradiated on the workpiece can be prevented from entering the imaging mechanism, thereby improving the S / N ratio of the captured image.

[0008] In one embodiment of the specific configuration of the inspection illumination device according to the present invention, the first optical system includes a first light source that emits first inspection light, a first polarization control element that polarizes the first inspection light emitted from the first light source in the predetermined direction, and a first beam splitter that is provided between the first polarization control element and the work and transmits the first inspection light that has passed through the first polarization control element to the work and reflects the first inspection light that has been reflected or scattered by the work; and the second optical system includes a second light source that emits second inspection light, and a first polarization control element that polarizes the first inspection light emitted from the second light source in the predetermined direction. and a second beam splitter provided between the second polarization control element and the workpiece, which transmits the second inspection light that has passed through the second polarization control element toward the workpiece and reflects the second inspection light that has been reflected or scattered by the workpiece, and further provided with a polarization selection mechanism provided on the first detection optical path and the second detection optical path, which is configured to block light polarized in the predetermined direction and transmit at least a portion of light polarized in a direction other than the predetermined direction.

[0009] In order to minimize the number of optical elements constituting the polarization selection mechanism while realizing its function with a simple configuration, the polarization selection mechanism may be a single polarizer provided in front of the imaging mechanism on the first detection optical path and the second detection optical path.

[0010] In order to make the first optical system and the second optical system compact, and to reduce the number of boundary surfaces and optical elements through which the first inspection light and the second inspection light pass before reaching the imaging mechanism, thereby suppressing attenuation of the radiant flux and increasing the radiant flux incident on the imaging mechanism, the first optical system includes a first light source that emits the first inspection light, and a first beam splitter that is provided between the first light source and the work and transmits the first inspection light emitted from the first light source to the work side and reflects the first inspection light reflected or scattered by the work, The second optical system may include a second light source that emits second inspection light, and a second beam splitter that is disposed between the second light source and the work and transmits the second inspection light emitted from the second light source toward the work and reflects the second inspection light reflected or scattered by the work, and the transmission-reflection surface of the second beam splitter is configured to polarize the second inspection light emitted from the second light source in the predetermined direction.

[0011] When the first beam splitter and the second beam splitter have a polarization function, a specific configuration example for enabling the polarization selection mechanism to achieve the same function without using a polarizer and further reducing the number of parts is as follows: the polarization state of light is maintained between the first side surface portion and the transmission-reflection surface of the first beam splitter on the first detection optical path, and the polarization state of light is maintained between the second side surface portion and the transmission-reflection surface of the second beam splitter on the second detection optical path. In this configuration, light whose polarization is changed due to reflection or scattering by the workpiece is reflected by each beam splitter and guided to the imaging mechanism, while light that is not irradiated on the workpiece remains polarized in a predetermined direction and can pass through the other beam splitter again to escape to the other light source. Therefore, the first beam splitter and the second beam splitter can function not only as a polarization control function but also as the polarization selection mechanism described above.

[0012] To ensure that the first inspection light and the second inspection light contain almost no polarization components other than those in a predetermined direction, thereby improving the accuracy of the linear polarization and enabling imaging of even minute defects on each side surface, the first optical system may further include a first irradiation-side polarizing element between the first light source and the transmission-reflection surface of the first beam splitter, which polarizes the first inspection light in the predetermined direction, and the second optical system may further include a second irradiation-side polarizing element between the second light source and the transmission-reflection surface of the second beam splitter, which polarizes the second inspection light in the predetermined direction.

[0013] To prevent the aforementioned S / N ratio from decreasing due to the influence of the incidence angle dependency of each optical element polarizing the first and second inspection lights in a predetermined direction and the extinction ratio of the polarizer, the first optical system may further include a first detection-side polarizing element between the transmission-reflection surface of the first beam splitter and the imaging mechanism, which transmits light polarized in a direction perpendicular to the predetermined direction, and the second optical system may further include a second detection-side polarizing element between the transmission-reflection surface of the second beam splitter and the imaging mechanism, which transmits light polarized in a direction perpendicular to the predetermined direction. Here, the concept of light polarized in a direction perpendicular to the predetermined direction includes not only light whose polarization direction is strictly 90 degrees relative to the predetermined direction, but also light whose polarization direction forms an angle close to 90 degrees with respect to the predetermined direction. In other words, the polarization direction may be such that the light polarized in the predetermined direction is blocked by the polarization selection mechanism, while light reflected or scattered at the side of the workpiece can pass through the polarization selection mechanism.

[0014] To prevent errors from occurring in the imaging results of the first and second side surfaces of the workpiece due to the spectral reflectance of the workpiece or chromatic aberration in the imaging mechanism, the second inspection light only needs to have the same wavelength as the first inspection light. In this case, the first inspection light and the second inspection light irradiated onto the workpiece have the same irradiation conditions, including not only polarization but also wavelength, so that, for example, only defects or scratches on the side surfaces of the workpiece can be revealed as differences in the imaging results.

[0015] Another aspect of the present invention includes a first optical system including a first illumination optical path through which first inspection light having a first wavelength reaches a first side portion of the workpiece and a first detection optical path from the first side portion to the imaging mechanism, a second optical system including a second illumination optical path through which second inspection light having a second wavelength different from the first wavelength reaches a second side portion of the workpiece opposite the first side portion and a second detection optical path from the second side portion to the imaging mechanism, a first wavelength-selective filter provided on the first detection optical path that transmits light of the first wavelength and blocks light of the second wavelength, and a second wavelength-selective filter provided on the second detection optical path that transmits light of the second wavelength and blocks light of the first wavelength. With this configuration, it is possible to simultaneously image the first and second side portions of the workpiece without using polarized light. In addition, each wavelength selection filter allows light that becomes a signal component reflected or scattered by the workpiece to enter the imaging mechanism, while light that becomes a noise component that passes through without being irradiated onto the workpiece is prevented from entering the imaging mechanism, thereby improving the S / N ratio in the captured image.

[0016] An inspection system equipped with the inspection illumination device according to the present invention and the imaging mechanism can image the entire periphery of the side surface of the workpiece at once, eliminating the need to use a complex transport mechanism to capture images of the entire periphery of the side surface of the workpiece multiple times, as was conventionally the case.

[0017] In order to be able to capture images of a wider range of the workpiece, even if the workpiece is, for example, cylindrical and has a curved side surface, the imaging mechanism may be equipped with an imaging element and an object-side telecentric lens that forms an image of the first and second side surfaces of the workpiece on the imaging element. [Effects of the Invention]

[0018] In this way, with the inspection illumination device according to the present invention, it is possible to obtain an image of the entire circumference of the side surface of the workpiece in a single image capture, thereby significantly shortening the time required for inspection. Furthermore, since only the light that becomes the signal component reflected or scattered by the side surface of the workpiece is incident on the imaging mechanism, and light that causes noise is blocked, the S / N ratio of the captured image can be increased. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic diagram showing an inspection illumination device and an inspection system according to a first embodiment of the present invention; [Figure 2] FIG. 10 is a comparison diagram showing the state of inspection light on the side surface of a workpiece when an object-side telecentric lens is used in the first embodiment, and the state of inspection light on the side surface of a workpiece when another general lens, such as a macro lens, is used. [Figure 3] FIG. 5 is a schematic diagram showing an inspection illumination device and an inspection system according to a second embodiment of the present invention. [Figure 4] FIG. 10 is a schematic diagram showing an inspection illumination device and an inspection system according to a third embodiment of the present invention. [Figure 5] FIG. 10 is a schematic diagram illustrating the polarization action of a polarizing beam splitter in the third embodiment. [Figure 6] FIG. 10 is a schematic diagram showing a modified example of the inspection illumination device and inspection system according to the third embodiment of the present invention. [Figure 7] FIG. 10 is a schematic diagram showing yet another modified example of the inspection illumination device and inspection system according to the third embodiment of the present invention. [Figure 8] FIG. 10 is a schematic diagram showing an inspection illumination device and an inspection system according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] An inspection illumination device 100 according to a first embodiment of the present invention and an inspection system 200 including the inspection illumination device 100 and an imaging mechanism 4 will be described with reference to FIG.

[0021] The inspection system 200 is used to visually inspect the shape and presence or absence of defects of a workpiece W, which has a generally flattened cylindrical shape, such as a tablet, based on captured images of the side surfaces W1 and W2. In the first embodiment, the optical axis OA of the lens 41 of the camera, which is the imaging mechanism 4, is set to be perpendicular to the center of the flat surface W3 (front surface) or bottom surface W4 (back surface) where the end faces of the workpiece W are formed. In other words, the central axis of the workpiece W and the optical axis OA of the lens 41 are aligned. Inspection light is irradiated from two directions, sandwiching the side surfaces W1 and W2 of the workpiece W, with the optical axis OA of the lens 41 set in this manner, by a pair of optical systems. More specifically, the optical axes of the inspection light beams, which travel in opposite directions near the workpiece W, are configured to be perpendicular to the optical axis OA of the lens 41. The inspection light beams reflected or scattered by the side surfaces W1 and W2 of the workpiece W are redirected by various optical elements and ultimately guided to the imaging mechanism 4, which captures the entire circumference of the side surfaces W1 and W2 of the workpiece W at once. Furthermore, the inspection light that is not irradiated onto the workpiece W is configured not to enter the imaging mechanism 4. The shape of the workpiece W is not limited to a cylindrical shape, and various shapes can be used.

[0022] More specifically, the inspection system 200 includes the imaging mechanism 4 and an inspection lighting device 100 configured to irradiate the side portions W1 and W2 of the workpiece W with inspection light polarized in a predetermined direction and to guide only the inspection light reflected or scattered by the workpiece W to the imaging mechanism 4.

[0023] First, details of the inspection illumination device 100 will be described with reference to Fig. 1. In the following description, the left half circumference of the side surfaces W1 and W2 of the workpiece W will be defined as the first side surface W1, and the right half circumference of the side surfaces W1 and W2 of the workpiece W will be defined as the second side surface W2.

[0024] The inspection illumination device 100 includes a first optical system 1 that irradiates a first side surface W1 with first inspection light polarized in a predetermined direction, a second optical system 2 that irradiates a second side surface W2 of the workpiece W that is opposite the first side surface W1 with second inspection light polarized in the same direction as the first inspection light, and a polarization selection mechanism 3 that is configured to cause at least some of the polarization components of the first inspection light and the second inspection light that have been reflected or scattered by the workpiece W and have undergone a change in polarization to enter an imaging mechanism 4, and to prevent light polarized in the predetermined direction from entering the imaging mechanism 4. In the first embodiment, the first optical system 1 and the second optical system 2 are arranged symmetrically with respect to a reference plane RP that includes the central axis of the workpiece W.

[0025] The first optical system 1 is shown in the left half of Fig. 1. The first optical system 1 includes a first illumination optical path L11 extending from the first light source 11 to the first side surface W1 of the workpiece W, and a first detection optical path L12 extending from the first side surface W1 to the imaging mechanism 4. The first illumination optical path L11 is an optical path that extends linearly in the left-right direction in Fig. 1. The first detection optical path L12 is an optical path that extends in a zigzag pattern and is reflected multiple times. The first illumination optical path L11 and the first detection optical path L12 overlap between the workpiece W and a first beam splitter 13, which will be described later.

[0026] Specifically, the first optical system 1 includes a first light source 11, a first polarization control element 12, a first beam splitter 13, a first mirror 14, and a first reflecting surface 15 of the common mirror CM. The first light source 11, the first polarization control element 12, and the first beam splitter 13 are arranged in a straight line in the left-right direction in Fig. 1 to form a first illumination optical path L11. The first beam splitter 13, the first mirror 14, and the first reflecting surface 15 of the common mirror CM are arranged in a crank shape to form a first detection optical path L12.

[0027] The first light source 11 emits light of a predetermined wavelength in a state of random polarization (natural light) as the first inspection light, and is configured by, for example, an LED.

[0028] The first polarization control element 12 is a polarizer that transmits only light polarized in a predetermined direction from the first inspection light emitted from the first light source 11, thereby linearly polarizing the first inspection light. The first polarization control element 12 is not limited to a polarizer, and may be a polarization conversion element, etc. Use of a polarization conversion element makes it possible to extract the first inspection light emitted from the first light source 11 as light polarized in a predetermined direction more efficiently than use of a polarizer. In the first embodiment, the first inspection light changes from a randomly polarized state to a P-polarized state by passing through the first polarization control element 12.

[0029] The first beam splitter 13 is, for example, a cube type, and the orientation of its transmission / reflection surface 13S is set so that the first inspection light in a P-polarized state that has passed through the first polarization control element 12 is transmitted to the first side surface of the workpiece W, and the first inspection light that has been reflected or scattered by the first side surface portion W1 of the workpiece W is reflected to the first mirror 14. Note that the first beam splitter 13 is not limited to a cube type, and may be a plate type.

[0030] The first mirror 14 has a reflecting surface oriented so as to bend the traveling direction of the light reflected by the first beam splitter 13 at a right angle and reflect it toward the common mirror CM. The light reflected by the first mirror 14 is further bent by 90 degrees by a first reflecting surface 15 of the common mirror CM and reflected toward the imaging mechanism 4.

[0031] Here, the width of the first inspection light traveling through the first illumination optical path L11 is set larger than the vertical and horizontal widths of the workpiece W. Therefore, the light of the first inspection light near the optical axis is illuminated onto the first side surface W1 of the workpiece W, but the light outside of that is not illuminated onto the workpiece W and instead enters the second beam splitter 23 of the second optical system 2, which will be described later. If the workpiece W is a tablet, its surface is a scattering surface, so the polarization state of the illuminated first inspection light is not preserved. Therefore, the first inspection light reflected or scattered by the first side surface W1 of the workpiece W changes from a P-polarized state to a randomly polarized state. On the other hand, the first inspection light that is not illuminated onto the workpiece W and enters the second optical system 2 travels through the second detection optical path L22 of the second optical system 2 while maintaining its P-polarized state, and reaches the polarization selection mechanism 3.

[0032] The second optical system 2 is an optical system shown in the right half of Fig. 1. The second optical system 2 includes a second illumination optical path L21 extending from the second light source 21 to the second side surface W2 of the workpiece W, and a second detection optical path L22 extending from the second side surface W2 to the imaging mechanism 4. The second illumination optical path L21 is an optical path that extends linearly in the left-right direction in Fig. 1. The second detection optical path L22 is an optical path that extends in a zigzag pattern and is reflected multiple times. The second illumination optical path L21 and the second detection optical path L22 overlap between the workpiece W and a second beam splitter 23, which will be described later.

[0033] Specifically, the second optical system 2 includes a second light source 21, a second polarization control element 22, a second beam splitter 23, a second mirror 24, and a second reflecting surface 25 of the common mirror CM. The arrangement of these optical elements is symmetrical to the arrangement of the optical elements of the first optical system 1 described above, and therefore a description thereof will be omitted.

[0034] The second light source 21 is of the same type and model as the first light source 11 and is configured by, for example, an LED. That is, the second light source 21 emits light in a randomly polarized state at the same predetermined wavelength as the first light source 11 as the second inspection light.

[0035] The second polarization control element 22 is a polarizer that transmits only light polarized in a predetermined direction from the second inspection light emitted from the second light source 21, thereby linearly polarizing the second inspection light. Note that the second polarization control element 22 is not limited to a polarizer, and may be a polarization conversion element, etc. In the first embodiment, the second inspection light changes from a randomly polarized state to a P-polarized state by passing through the second polarization control element 22. In other words, the first inspection light and the second inspection light that have passed through each polarization control element are irradiated onto the workpiece W with the same wavelength and the same polarization state.

[0036] The second beam splitter 23 is, for example, a cube type, and the orientation of its transmission / reflection surface 23S is set so that the second inspection light in a P-polarized state that has passed through the second polarization control element 22 is transmitted to the second side surface of the workpiece W, and the second inspection light that has been reflected or scattered by the second side surface portion W2 of the workpiece W is reflected to the second mirror 24. The second beam splitter 23 is not limited to a cube type, and may also be a plate type.

[0037] The second mirror 24 has a reflecting surface oriented so as to bend the traveling direction of the light reflected by the second beam splitter 23 at a right angle and reflect it toward the common mirror CM. The light reflected by the second mirror 24 is further bent by 90 degrees by a second reflecting surface 25 of the common mirror CM and reflected toward the imaging mechanism 4.

[0038] Here, the width of the second inspection light traveling through the second irradiation optical path L21 is set larger than the vertical and horizontal widths of the workpiece W. Therefore, the light of the second inspection light near the optical axis is irradiated onto the second side surface W2 of the workpiece W, but the light outside of that is not irradiated onto the workpiece W and instead enters the first beam splitter 13 of the first optical system 1 described above. Like the first inspection light, the second inspection light reflected or scattered by the second side surface W2 of the workpiece W also changes from P polarization to random polarization. On the other hand, the second inspection light that is not irradiated onto the workpiece W and enters the first optical system 1 travels through the first detection optical path L12 of the first optical system 1 while maintaining its P polarization state, and reaches the polarization selection mechanism 3.

[0039] The polarization selection mechanism 3 is provided on the first detection optical path L12 and the second detection optical path L22 between the common mirror CM and the imaging mechanism 4. The polarization selection mechanism 3 is configured to transmit at least a portion of the light reflected or scattered by the first side surface W1 or the second side surface W2 of the workpiece W, while preventing the components of the first inspection light and the second inspection light that are not irradiated onto the workpiece W from entering the imaging mechanism 4. More specifically, the polarization selection mechanism 3 is a polarizer configured to transmit S-polarized light and block P-polarized light. Therefore, the first inspection light and the second inspection light that are reflected or scattered by the workpiece W and reach the polarization selection mechanism 3 are in a random polarization state, and the S-polarized light enters the imaging mechanism 4. On the other hand, the first inspection light and the second inspection light that are not irradiated onto the workpiece W travel only by reflection on the second detection optical path L22 and the first detection optical path L12, and therefore the P-polarized state is maintained until they reach the polarization selection mechanism 3. Therefore, the first inspection light and the second inspection light that are not irradiated onto the workpiece W are blocked by the polarization selection mechanism 3 and do not enter the imaging mechanism 4.

[0040] Finally, the imaging mechanism 4 will be described in detail. The imaging mechanism 4 includes an imaging element 43, a lens 41, and an aperture 42 that constitute an object-side telecentric lens that images the first side surface W1 and the second side surface W2 of the workpiece W on the imaging element 43. As shown in FIG. 1, only the first inspection light reflected or scattered by the first side surface W1 of the workpiece W and the second inspection light reflected or scattered by the second side surface W2 of the workpiece W are simultaneously incident on the imaging mechanism 4. Therefore, the entire circumference of the side surfaces W1 and W2 of the workpiece W can be imaged simultaneously on the imaging element 43. Furthermore, because an object-side telecentric lens is used, the chief rays are not inclined at any point on the side surfaces W1 and W2 of the workpiece W, which are circularly curved surfaces, as shown in FIG. 2, and the chief rays are parallel to each other. On the other hand, when a typical lens, such as a macro lens, is used, the chief rays of the lens are inclined toward the outer edge. Therefore, when the workpiece W has a cylindrical shape, using an object-side telecentric lens allows a wider area of ​​the workpiece W to be imaged than when using a macro lens.

[0041] With the inspection illumination device 100 and inspection system 200 of the first embodiment configured as described above, the first inspection light and the second inspection light can be simultaneously irradiated along the entire circumference of the side surface portions W1, W2, and only the first inspection light and the second inspection light reflected or scattered by the first side surface portion W1 and the second side surface portion W2 of the workpiece W can be incident on the imaging mechanism 4 at one time. As a result, a captured image capturing the entire circumference of the side surface portions W1, W2 of the workpiece W can be obtained with just one imaging. Therefore, compared to the conventional method of capturing images of the side surface portions W1, W2 of the workpiece W in two separate images, each halfway around the circumference, the time required to capture the entire circumference of the side surface portions W1, W2 can be reduced by approximately half.

[0042] Furthermore, the first inspection light and the second inspection light, which become noise components that are not irradiated onto the workpiece W, are not incident on the imaging mechanism 4, improving the S / N ratio of the signal light originating from the side portions W1, W2 of the workpiece W. In this way, only the light originating from the side portions W1, W2 of the workpiece W is reflected in the captured image, making it possible to detect, for example, minute shape differences around the entire periphery of the side portions W1, W2 of the workpiece W, as well as minute defects, with high accuracy.

[0043] Furthermore, since the first optical system 1 and the second optical system 2 are bilaterally symmetrical and have the same configuration, light of the same wavelength and the same polarization state can be irradiated onto the first side surface W1 and the second side surface W2. Therefore, substantially the same illumination conditions can be achieved over the entire circumference of the side surfaces W1 and W2 of the workpiece W, and detection errors due to, for example, chromatic aberration in the imaging mechanism 4 can be prevented.

[0044] Next, an inspection illumination device 100 and an inspection system 200 according to a second embodiment of the present invention will be described with reference to Fig. 3. In each embodiment described below, the same reference numerals will be used to designate components corresponding to those described in the first embodiment.

[0045] The inspection illumination device 100 of the second embodiment differs from the first embodiment in the arrangement and alignment of the optical elements in each optical system. In the first embodiment, the first light source 11 and the second light source 21 were configured to illuminate the first side surface portion W1 and the second side surface portion W2 straight from the side of the workpiece W so that the first illumination light path L11 and the second illumination light path L21 were linear. In contrast, in the second embodiment, the first light source 11 and the second light source 21 are provided on the imaging mechanism 4 side when viewed from the workpiece W, and the light emission direction thereof is set to be parallel to the optical axis OA of the lens 41. In other words, the first illumination light path L11 and the second illumination light path L21 are configured to be substantially L-shaped, and the first detection light path L12 and the second detection light path L22 are configured to be zigzag, as in the first embodiment.

[0046] More specifically, each optical system is configured so that the inspection light travels in the following order: light sources 11, 21, polarization control elements 12, 22, beam splitters 13, 23, mirrors 14, 24, side surfaces W1, W2 of the workpiece W, mirrors 14, 24, beam splitters 13, 23, reflecting surfaces 15, 25 of the common mirror CM, polarization selection mechanism 3, and imaging mechanism 4. That is, instead of directly irradiating the inspection light transmitted through the beam splitters 13, 23 onto the side surfaces W1, W2 of the workpiece W as in the first embodiment, the inspection light is first reflected by a mirror and then irradiated onto the side surfaces W1, W2 of the workpiece W.

[0047] With the inspection illumination device 100 and inspection system 200 of the second embodiment, the light sources and the imaging mechanism 4 can be arranged together, resulting in a more compact device configuration than the first embodiment. Also, like the first embodiment, the entire circumference of the side portions W1 and W2 of the workpiece W can be imaged at once, and the inspection light that is not irradiated onto the workpiece W is prevented from entering the imaging mechanism 4, thereby increasing the S / N ratio.

[0048] Next, an inspection illumination device 100 and an inspection system 200 according to a third embodiment will be described with reference to FIGS.

[0049] The inspection illumination device 100 and the inspection system 200 of the third embodiment differ from those of the first embodiment in that they do not include polarization control elements 12 and 22, do not include a polarizer immediately before the imaging mechanism 4, and the beam splitters 13 and 23 are polarizing beam splitters. As shown in FIG. 5 , in the third embodiment, the first beam splitter 13 and the second beam splitter 23 are polarizing beam splitters configured to transmit the P-polarized component and reflect the S-polarized component of light incident on the transmission-reflection surfaces 13S and 23S. The polarization state of light is maintained between the first side surface W1 and the transmission-reflection surface 13S of the first beam splitter 13 on the first detection optical path L11, and the polarization state of light is maintained between the second side surface W2 and the transmission-reflection surface 23S of the second beam splitter 23 on the second detection optical path L22. Specifically, no optical elements such as polarizers are provided between the transmission / reflection surfaces 13S, 23S of each beam splitter and the side surfaces W1, W2 of the workpiece W, and the polarization state of the light is maintained. Below, it will be explained that in the third embodiment as well, light that is irradiated onto the workpiece W and reflected or scattered enters the imaging mechanism 4, and light that is not irradiated onto the workpiece W does not enter the imaging mechanism 4.

[0050] The first inspection light in a random polarization state emitted from the first light source 11 is transmitted through the transmission / reflection surface 13S of the first beam splitter 13 so that the P-polarized component is transmitted to the workpiece W side and the S-polarized component is reflected to the opposite side of the imaging mechanism 4.

[0051] Of the first inspection light that has passed through the first beam splitter 13 and become P-polarized, the light that is irradiated onto the first side surface W1 of the workpiece W is changed to a random polarization state by reflection or scattering on the diffuse reflection surface of the workpiece W. The first inspection light that returns from the workpiece W to the first beam splitter 13 is transmitted by the transmission-reflection surface 13S to the first light source 11 side with the P-polarized component transmitted, and only the S-polarized component reflected, and is guided to the imaging mechanism 4 by the first mirror 14 and the first reflection surface 15.

[0052] On the other hand, of the first inspection light that has passed through the first beam splitter 13 and become P-polarized, the light that has not been irradiated onto the first side surface W1 of the workpiece W remains P-polarized and is incident on the transmission-reflection surface 23S of the second beam splitter 23. Here, the second beam splitter 23 has the same optical properties as the first beam splitter 13, and transmits the P-polarized component. Therefore, the first inspection light that has not been irradiated onto the workpiece W can pass through the second beam splitter 23 and escape to the second light source 21, and does not enter the imaging mechanism 4 from the second optical system 2.

[0053] In the second optical system 2 , as in the first optical system 1 described above, only the component of the second inspection light that is irradiated onto the workpiece W is incident on the imaging mechanism 4 .

[0054] As described above, the inspection illumination device 100 and inspection system 200 of the third embodiment can omit the polarizers that function as the polarization control elements 12, 22 and polarization selection mechanism 3 in the first embodiment, and allow only the inspection light irradiated onto the side portions W1, W2 of the workpiece W to be incident on the imaging mechanism 4, thereby making it possible to image the entire circumference of the side portions W1, W2 at once. Furthermore, by having the beam splitters 13, 23 function as two polarizers, the number of times that the radiant flux is halved can be reduced by two, so that in the third embodiment, the radiant flux incident on the imaging mechanism 4 can be four times larger than in the first embodiment.

[0055] A modified example of the third embodiment will be described with reference to Fig. 6. In this modified example, the polarization control elements 12 and 22 and the polarizers provided as the polarization selection mechanism 3 in the inspection illumination device 100 and inspection system 200 of the second embodiment shown in Fig. 3 are omitted, and the first beam splitter 13 and the second beam splitter 23 are replaced with polarizing beam splitters that transmit P-polarized light components and reflect S-polarized light components. As is clear from the optical path diagram in Fig. 6, in this modified example, the first beam splitter 13 and the second beam splitter 23 also function as the polarization selection mechanism 3, so that only the inspection light irradiated onto the side portions W1 and W2 of the workpiece W enters the imaging mechanism 4.

[0056] Another modification of the third embodiment will be described with reference to Fig. 7. In the modification shown in Fig. 6, polarization control elements 12, 22 and polarization selection mechanism 3 are omitted by using polarization beam splitters 13, 23. However, to enable more precise control of the polarization state, an element for controlling polarization may be provided in addition to polarization beam splitters 13, 23. Specifically, as shown in Fig. 7, a first illumination-side polarizing element 17 that transmits P-polarized light may be provided between first light source 11 and first beam splitter 13, which transmits P-polarized light and reflects S-polarized light at its transmission-reflection surface 13S, and a first detection-side polarizing element 18 that transmits S-polarized light may be provided between transmission-reflection surface 13S of first beam splitter 13 and imaging mechanism 4. Similarly, a second illumination-side polarizing element 27 that transmits P-polarized light may be provided between second light source 21 and second beam splitter 23, which transmits P-polarized light and reflects S-polarized light at transmission-reflection surface 23S, and a second detection-side polarizing element 28 that transmits S-polarized light may be provided between transmission-reflection surface 23S of second beam splitter 23 and imaging mechanism 4. In this modified example, first detection-side polarizing element 18 and second detection-side polarizing element 28 may be integrally configured as a single polarizer, similar to the polarization selection mechanism 3, and may be provided between common mirror CM and imaging mechanism 4.

[0057] Next, an inspection illumination device 100 and an inspection system 200 according to a fourth embodiment will be described with reference to Fig. 8. In the fourth embodiment, the wavelengths of the first inspection light and the second inspection light are made different, so that only the light irradiated onto the side portions W1 and W2 of the workpiece W enters the imaging mechanism 4.

[0058] That is, the first optical system 1 includes a first illumination optical path L11 through which first inspection light having a first wavelength reaches a first side surface W1 of the workpiece W, and a first detection optical path L12 from the first side surface W1 to the imaging mechanism 4. In addition, a first wavelength selection filter 16 is further provided on the first detection optical path L12, which transmits light of the first wavelength and blocks light of the second wavelength.

[0059] The second optical system 2 includes a second irradiation optical path L21 through which second inspection light having a second wavelength different from the first wavelength reaches a second side surface W2 of the workpiece W, which is on the opposite side of the first side surface W1, and a second detection optical path L22 from the second side surface W2 to the imaging mechanism 4. Furthermore, a second wavelength selection filter 26 is further provided on the second detection optical path L22, which transmits light of the second wavelength and blocks light of the first wavelength.

[0060] In this embodiment, the first wavelength corresponds to blue, and the second wavelength corresponds to red.

[0061] Specifically, the first optical system 1 includes a first light source 11 that emits light of a first wavelength corresponding to blue, a first beam splitter 13, and a first mirror 14 and a first reflecting surface 15 that, together with the first beam splitter 13, form a first detection light path L12. In the fourth embodiment, a first wavelength-selective filter 16 that transmits blue light and blocks red light is provided between the first beam splitter 13 and the first mirror 14. Note that, in the fourth embodiment, the first light source 11 of the first optical system 1 is configured to emit light in the horizontal direction, as in the first embodiment; however, as in the second embodiment, the first light source 11 may be configured to emit light in the same direction as the optical axis OA of the imaging mechanism 4, and the light reflected by the beam splitter or mirror may be incident on the workpiece W.

[0062] The second optical system 2 is configured to be plane-symmetrical to the first optical system 1 with respect to a reference plane RP including the central axis of the workpiece W. That is, the second optical system 2 includes a second light source 21 that emits light of a second wavelength corresponding to red, a second beam splitter 23, and a second mirror 24 and a second reflecting surface 25 that, together with the second beam splitter 23, form a second detection light path L22. In the fourth embodiment, a second wavelength-selective filter 26 that transmits red light and blocks blue light is provided between the second beam splitter 23 and the second mirror 24. Note that, in the fourth embodiment, the second light source 21 of the second optical system 2 is configured to emit light horizontally, as in the first embodiment; however, as in the second embodiment, the second light source 21 may be configured to emit light in the same direction as the optical axis OA of the imaging mechanism 4, and the light reflected by the beam splitter or mirror may be incident on the workpiece W.

[0063] In the inspection illumination device 100 and inspection system 200 of the fourth embodiment configured as described above, the first optical system 1 allows only the blue light reflected or scattered by the first side surface of the workpiece W to pass through the first detection optical path L12 and enter the imaging mechanism 4, and the red light emitted from the second light source 21 that has not been irradiated onto the workpiece W can be blocked by the first wavelength selection filter 16 to prevent it from entering the imaging mechanism 4. Similarly, the second optical system 2 allows only the red light reflected or scattered by the second side surface of the workpiece W to pass through the second detection optical path L22 and enter the imaging mechanism 4, and the blue light emitted from the first light source 11 that has not been irradiated onto the workpiece W can be blocked by the second wavelength selection filter 26 to prevent it from entering the imaging mechanism 4.

[0064] Therefore, the entire circumference of the side portions W1 and W2 of the workpiece W can be imaged at once, and light that does not originate from the side portions W1 and W2 of the workpiece W can be blocked, improving the S / N ratio of the signal related to the side portions W1 and W2.

[0065] Other embodiments will be described.

[0066] The polarizer provided as the polarization selection mechanism in the first and second embodiments is not limited to being provided between the common mirror and the imaging mechanism. The polarization selection mechanism may be provided anywhere between the transmission / reflection surface of the beam splitter and the imaging mechanism, and the polarization selection mechanism may be configured by providing a polarizer for each of the first optical system and the second optical system, rather than using a single polarizer.

[0067] The relationship between P-polarized light and S-polarized light described in the first and second embodiments can be interchanged, and the characteristics of the polarization control element and polarizer can be selected accordingly. Furthermore, the polarization selection mechanism only needs to block the polarized light of the first inspection light and the second inspection light when they are incident on the side surface of the workpiece, and transmit other polarized light components.

[0068] The workpieces targeted by the present invention are not limited to tablets, but may be of various shapes and materials. For example, if the workpiece is not cylindrical, the plane or bottom surface is defined as the portion intersecting the optical axis of the lens, and the surface perpendicular to the plane or bottom surface is defined as the side surface, and the orientation of each optical system can be set accordingly. Furthermore, the optical axis of the lens is not limited to being perpendicular to the plane or bottom surface of the workpiece, but may intersect at an angle at a predetermined angle. In addition, the irradiation light path is not limited to being perpendicular to the optical axis of the lens, but may intersect at an angle.

[0069] The imaging mechanism is not limited to one that captures images from the flat surface side of the workpiece, and may also capture images from the bottom surface side. Furthermore, the imaging mechanism may be configured to capture images not only of the side surface of the workpiece, but also of the entire periphery of the side surface, as well as the flat surface or bottom surface simultaneously. In the first embodiment, for example, the reflecting mirrors and common mirror may be omitted, and the imaging mechanism may be configured so that light from the side surface and light from the flat surface simultaneously enter the imaging mechanism.

[0070] In the first to third embodiments, the first light source and the second light source are configured as separate light sources, but they may be, for example, a single shared light source. The shared light source may be split into two optical paths by a mirror or the like, and each light may be incident on a polarization control element or a polarizing beam splitter, so that each light has the same polarization state. Furthermore, the first light source and the second light source may have different wavelengths.

[0071] The wavelength of the inspection light emitted from each light source in the fourth embodiment may be selected as appropriate. That is, it is not limited to blue or red, and it is sufficient that the wavelength is selected so that only desired light is incident on the imaging mechanism using a wavelength-selective filter. In the fourth embodiment, the wavelength-selective filter may be provided anywhere between the transmission-reflection surface of the beam splitter and the imaging mechanism.

[0072] The first side surface portion and the second side surface portion are not limited to those defined by dividing the entire circumference of the side surface portion of the workpiece in half. For example, the first side surface portion irradiated with the first inspection light and the second side surface portion irradiated with the second inspection light may partially overlap, or there may be an area between the first side surface portion and the second side surface portion that is not irradiated with the inspection light.

[0073] In addition, various modifications of the embodiments and combinations of parts of the embodiments may be made as long as they do not go against the spirit of the present invention. [Explanation of symbols]

[0074] 1 :1st optical system 2:Second optical system 3: Polarization selection mechanism 4: Imaging mechanism 11: 1st light source 12: First polarization control element 13: First beam splitter 16: First wavelength selection filter 17: First irradiation side polarizing element 18: First detection side polarizing element 21:Second light source 22: Second polarization control element 23: Second beam splitter 26: Second wavelength selection filter 27: Second illumination side polarizing element 28: Second detection side polarizing element 100: Inspection lighting device 200: Inspection system W: Work W1: 1st side part W2: Second side part

Claims

1. An inspection lighting device applied to a workpiece that reflects or scatters irradiated light by changing the polarization state, a first optical system including a first irradiation optical path through which a first inspection light reaches a first side surface of the workpiece, and a first detection optical path from the first side surface to an imaging mechanism, and configured so that the first inspection light is irradiated onto the first side surface while being polarized in a predetermined direction; a second optical system including a second irradiation optical path through which the second inspection light reaches a second side surface of the workpiece opposite the first side surface, and a second detection optical path from the second side surface to the imaging mechanism, and configured so that the second inspection light is irradiated onto the second side surface while being polarized in the same direction as the first inspection light; An inspection lighting device configured to cause at least some of the polarization components of the first inspection light and the second inspection light, which have been reflected or scattered by the work and have undergone a change in polarization, to be incident on the same imaging mechanism, while preventing light polarized in the specified direction from being incident on the imaging mechanism.

2. The first optical system is a first light source that emits a first inspection light; a first polarization control element that polarizes the first inspection light emitted from the first light source in the predetermined direction; a first beam splitter that is provided between the first polarization control element and the work, and transmits the first inspection light that has passed through the first polarization control element to the work side, and reflects the first inspection light that has been reflected or scattered by the work, The second optical system is a second light source that emits second inspection light; a second polarization control element that polarizes the second inspection light emitted from the second light source in the predetermined direction; a second beam splitter provided between the second polarization control element and the work, for transmitting the second inspection light that has passed through the second polarization control element to the work side, and for reflecting the second inspection light that has been reflected or scattered by the work, 2. The inspection illumination device according to claim 1, further comprising a polarization selection mechanism provided on the first detection optical path and the second detection optical path, configured to block light polarized in the predetermined direction and transmit at least a portion of light polarized in directions other than the predetermined direction.

3. 3. The inspection illumination device according to claim 2, wherein the polarization selection mechanism is a single polarizer provided in front of the imaging mechanism on the first detection optical path and on the second detection optical path.

4. The first optical system is a first light source that emits a first inspection light; a first beam splitter that is provided between the first light source and the work, transmits the first inspection light emitted from the first light source to the work side, and reflects the first inspection light reflected or scattered by the work; The second optical system is a second light source that emits second inspection light; a second beam splitter that is provided between the second light source and the work, and transmits the second inspection light emitted from the second light source to the work side, and reflects the second inspection light reflected or scattered by the work, 2. The inspection illumination device according to claim 1, wherein the first beam splitter and the second beam splitter are polarizing beam splitters configured to transmit components of the incident light polarized in the predetermined direction and reflect components polarized in a direction perpendicular to the predetermined direction.

5. The first optical system is a first illumination-side polarizing element disposed between the first light source and the transmission-reflection surface of the first beam splitter to polarize the first inspection light in the predetermined direction; The second optical system is 5. The inspection illumination device according to claim 4, further comprising a second illumination-side polarizing element disposed between the second light source and the transmission-reflection surface of the second beam splitter for polarizing the second inspection light in the predetermined direction.

6. The first optical system is a first detection-side polarizing element that transmits light polarized in a direction orthogonal to the predetermined direction, between the transmission-reflection surface of the first beam splitter and the imaging mechanism; The second optical system is 6. An inspection illumination device according to claim 4, further comprising a second detection-side polarizing element between the transmission-reflection surface of the second beam splitter and the imaging mechanism, the second detection-side polarizing element transmitting light polarized in a direction perpendicular to the predetermined direction.

7. 7. The inspection illumination device according to claim 1, wherein the second inspection light has the same wavelength as the first inspection light.

8. a first optical system including a first irradiation optical path through which first inspection light having a first wavelength reaches a first side surface portion of the workpiece, and a first detection optical path from the first side surface portion to an imaging mechanism; a second optical system including a second irradiation optical path through which second inspection light having a second wavelength different from the first wavelength reaches a second side surface of the workpiece opposite the first side surface, and a second detection optical path from the second side surface to the imaging mechanism; a first wavelength selection filter provided on the first detection optical path, the first wavelength selection filter transmitting light of the first wavelength and blocking light of the second wavelength; a second wavelength selection filter provided on the second detection optical path, the second wavelength selection filter transmitting light of the second wavelength and blocking light of the first wavelength, An inspection illumination device configured to direct at least a portion of the first inspection light and the second inspection light reflected or scattered by the workpiece into the same imaging mechanism.

9. The inspection illumination device according to any one of claims 1 to 8, An inspection system comprising the imaging mechanism.

10. The imaging mechanism An imaging element; The inspection system according to claim 9 , further comprising an object-side telecentric lens that forms an image of the first side surface portion and the second side surface portion of the workpiece on the imaging element.

Images