JP2007322316A - Polarization-selective imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarization-selective imaging device, constituted so that a plurality of linearly polarized lights are controlled to be changed-over by a linearly polarized light source to irradiate a subject and detection is performed surely on the basis of the reflected light from the subject by one unit of imaging device without detecting small dust or the like in a sample, on the basis of the level difference by individually imaging P-polarized light and S-polarized light using a two-dimensional CCD image sensor, using a polarization camera equipped with a polarizing prism for spectrally diffracting the reflected light from the sample into the P-polarized light and the S-polarized light, in inspection of dust, flaus, uneveness, etc. in a conventional light-transmitting material. <P>SOLUTION: The polarization-selective imaging device is equipped with a linearly polarized light illumination means, comprising a linearly polarized light forming means for forming a plurality of linearly polarized lights different in the polarization direction, an imaging element for photoelectrically converting the optical image, obtained by imaging the reflected light due to the irradiation of the subject with the linearly polarized lights via a lens to form an image signal, an image signal processing means for performing the comparison processing of the image signal, formed from the drive means thereof and the imaging element and a polarization control means for controlling the linearly polarized light-forming means by each frame, in synchronism with the drive means of the imaging element. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polarization-selective imaging apparatus that selects a plurality of linearly polarized light having different polarization directions and irradiates a subject to inspect dust, scratches, unevenness, and the like.

  In the industrial field, when inspecting dust, scratches, unevenness on the surface of parts and light-transmitting materials, foreign matter mixed in liquid, etc., use polarized waves reflected from the subject to inspect visually or with a TV camera. There are many. For example, when inspecting the surface or internal dust, scratches, unevenness, special wrinkles, etc. of optical glass materials, etc., the reflected light or transmitted light is directly monitored visually through a polarizing filter, or a plurality of TV camera lenses. Are equipped with polarizing filters with different polarization directions, and the output images are monitored and inspected.

  For example, in Patent Document 1 described later, in the case of a sample having a high regular reflectance of light such as metal or glass, the reflectance of the P-polarized light and the S-polarized light varies depending on the incident angle of the light with respect to the sample. Using a polarization camera equipped with a polarizing prism that splits light into P-polarized light and S-polarized light, P-polarized light and S-polarized light are individually imaged by a two-dimensional CCD image sensor, and P-polarized imaging data and S-polarized imaging data are obtained. The surface condition such as a small scratch on the sample is detected based on the difference between the P-polarized light amount and the S-polarized light amount.

Further, in Patent Document 2 described later, the surface of the coated steel sheet in which the insulating opaque film layer is formed in the lower layer and the insulating transparent film layer is formed in the upper layer is illuminated, and the surface of the coated steel sheet is imaged by an imaging device. In the wrinkle inspection method, the surface of the coated steel sheet is illuminated at or near the Brewster angle, and the reflected light from the surface of the coated steel sheet is converted into P-polarized light by the first imaging device at the regular reflection angle or an angle close thereto. Provided is a wrinkle inspection method and apparatus capable of distinguishing wrinkles between a lower insulating opaque coating layer and an upper insulating transparent coating layer by imaging through a filter and a second imaging device through an S polarization filter. is doing.
Japanese Patent Publication No. 2000-035403 Japanese Patent Publication No. 2002-214150

  However, in order to inspect dust, scratches, unevenness, etc. inside the component surface or light transmissive material, only polarized light of P-polarized light and S-polarized light reflected from the subject is used. In addition, due to changes in unevenness or changes in the direction of scratches, the degree of light hitting the subject slightly changes, and there is a risk that it may be difficult to find dust, scratches, unevenness, and the like.

  In addition, in order to easily detect dust, scratches, unevenness, etc., in order to detect and use polarized waves in a plurality of polarization directions, a plurality of imaging devices are required, which increases the size and cost of the inspection device. I will.

As a result of intensive research in view of the above, the inventor of the present application selects and controls a plurality of linearly polarized light generated by the linearly polarized light generating means and irradiates the subject, and reliably detects dust, scratches, unevenness, etc. of the subject by the reflected light. Therefore, this problem has been solved by the following means.
(1) Photoelectric conversion of a linearly polarized light illuminating means comprising linearly polarized light generating means for generating a plurality of linearly polarized lights having different polarization directions, and an optical image formed by imaging the reflected light from the irradiation of the linearly polarized light on the subject through a lens An image sensor for generating a video signal and its driving means, a video signal processing means for comparing the video signal generated from the image sensor, and a polarization control means for controlling the linearly polarized light generation means,
The polarization selection type imaging apparatus, wherein the polarization control means controls the linearly polarized light generation means for each frame in synchronism with the driving means of the imaging device.

(2) The polarized light as described in (1) above, wherein the linearly polarized light generating means irradiates the subject with linearly polarized light having different polarization directions and linearly polarized light at intervals of 15 ° to 90 °. Selective imaging device.

(3) A linearly polarized illumination unit comprising a linearly polarized light generating unit that generates a plurality of combinations of a plurality of linearly polarized light having different polarization directions and a combination of two waves having the same narrow angle and different polarization directions, and a lens. A polarization beam splitter that splits the reflected light by irradiation of the linearly polarized light incident on the subject in two directions, and photoelectrically converts each optical image split in two directions by the polarization beam splitter to generate a video signal An image pickup device and its driving means, a video signal processing means for comparing and processing a video signal generated from the image pickup device, and a pair of two reflected light waves are provided between the lens and the polarization beam splitter. A polarization switch composed of a liquid crystal element that selects a plurality of sets of linearly polarized light at regular intervals and controls the plurality of sets of linearly polarized light to be in phase, and the linearly polarized light generation And a polarization control means for controlling the polarization switch, wherein the polarization control means controls the linearly polarized light generation means and the polarization switch for each frame in synchronization with the drive means of the imaging device. A polarization-selective imaging device characterized by the above.

(4) The linearly polarized light generating means irradiates the subject with a plurality of sets of linearly polarized light having different directions of polarization directions, wherein the two waves are converted into a pair of linearly polarized lights having orthogonal directions of polarization directions. The polarization-selective imaging device according to item (3), characterized in that:

(5) Any of the above (1) to (4), wherein the linearly polarized light generating means comprises a light source and a plurality of liquid crystal elements capable of controlling the direction of polarization direction by the polarization control means. 2. A polarization-selective imaging device according to item 1.

(6) The linearly polarized light generating means includes a plurality of light sources that can be controlled by the polarization control means, and a plurality of polarizing filters having different polarization directions, according to the above (1) to (4), The polarization selective imaging device according to any one of the above.

(7) The polarization control means has a pair of linearly polarized light beams in the two waves, linearly polarized light having a vibration surface horizontal to the polarization beam splitter incident surface, and a vibration surface perpendicular to the polarization beam splitter incident surface. The polarization-selective imaging device according to any one of (3) to (6) above, wherein the polarization switch is controlled so as to be linearly polarized light.

(8) The video signal processing means is capable of detecting video signals exceeding a preset threshold value by comparing video signal levels generated by the imaging device according to a plurality of polarization directions. The polarization-selective imaging device according to any one of (7).

(9) The video signal processing means includes a plurality of video signals generated by the image sensor and the video signal generated by the image sensor by reflected light from a reference subject in which the polarization of the reflected light is less likely to change compared to the irradiation light. The polarization-selective imaging device according to any one of (1) to (7), wherein a level of a video signal according to a polarization direction of the video signal is compared and a video signal exceeding a preset threshold value can be detected. .

(10) Any one of (1) to (9) above, wherein when the video signal processing means detects a video signal exceeding the preset threshold, an alarm signal can be output. Polarization selective imaging device.

According to the present invention, the following effects are exhibited.
1. According to the invention of claim 1 of the present invention,
A linearly polarized light illumination means comprising a linearly polarized light generating means for generating a plurality of linearly polarized lights having different polarization directions can select and control a plurality of linearly polarized light most suitable for inspection of dust, scratches, unevenness, etc. Without changing the illumination angle for the subject or setting the illumination means to a special illumination angle, or tilting the subject to slightly change the light exposure, It is no longer necessary to perform the troublesome work of finding scratches, unevenness, etc., and the linearly polarized illumination means can select the most suitable illumination position and imaging device position for imaging the subject, easily and reliably on the subject. A specimen can be inspected for dust, scratches, unevenness, and the like.

  In addition, the linearly polarized light generating means for illuminating the subject can select and control a plurality of linearly polarized light most suitable for inspection of dust, scratches, unevenness, etc. and irradiate the subject, and the linearly polarized light generating means can be controlled by the polarized light controlling means. For example, an optical image of each polarization direction is photoelectrically converted by an imaging device to generate a video signal, which can be output as a video signal most suitable for detection of dust, scratches, unevenness, etc., so one polarization selective imaging device Thus, an efficient and reliable automatic wrinkle inspection device, automatic wrinkle sorting device and the like can be constructed.

  Furthermore, a video signal that selects and controls a plurality of linearly polarized light most suitable for inspection of dust, scratches, unevenness, etc., irradiates the subject, photoelectrically converts the reflected light, generates a video signal, and compares the video signal. Because it has a processing means, it is not necessary to visually inspect for dust, scratches, unevenness, etc., and it can be automated and has high detection accuracy and high quality automatic scissors inspection equipment, automatic scissors sorting equipment, etc. Can do.

  In addition, video signals can be sent to internal or external automatic flaw inspection devices, automatic flaw sorting devices, etc., and at the same time, video signals that are easy to detect dust, scratches, unevenness, etc. can be monitored directly on the video monitor as fist images, Visual confirmation of dust, scratches, unevenness, etc. of the subject can be made more reliably.

  Furthermore, since the polarization control unit can control the linearly polarized light generating unit for each frame in synchronization with the driving unit for the image sensor, for example, a plurality of polarization directions for each frame photoelectrically converted by the image sensor. If this video signal is output, it is a progressive scan method suitable for computer processing, and the video signal can be compared at high speed, and at the same time, the video signal of an image having no flickering and excellent vertical resolution can be supplied to the video monitor.

2. According to the invention of claim 2 of the present invention,
In addition to the effect of the first aspect, if the linearly polarized light generating unit irradiates the subject with linearly polarized light having different polarization directions and linearly polarized light at intervals of 15 ° to 90 °, dust, scratches, unevenness, etc. Since the object can be irradiated with linearly polarized light having a plurality of polarization directions most suitable for detection, a video signal having a plurality of polarization directions is output for each frame photoelectrically converted by the image sensor, and one polarization selective imaging is performed. With the apparatus, an efficient and reliable automatic wrinkle inspection device, automatic wrinkle sorting device and the like can be constructed.

3. According to the invention of claim 3 of the present invention,
Since the linearly polarized light generating means for irradiating the subject can irradiate the subject with a plurality of combinations having the same narrow angle and different polarization directions with two waves in the polarization direction most suitable for inspection of dust, scratches, unevenness, etc. Without changing the irradiation angle of the subject by the skilled worker or setting the illumination means to a special irradiation angle, or tilting the subject to slightly change the light hit condition It is no longer necessary to perform the cumbersome task of finding dust, scratches, unevenness, etc., and it is possible to select the illumination position and the position of the imaging device that are most suitable for imaging the subject. It is possible to inspect for scratches and unevenness.

  In addition, the linearly polarized light generating means for irradiating the subject irradiates the subject with a plurality of combinations having the same narrow angle and different polarization directions with two waves in the polarization direction most suitable for inspection of dust, scratches, unevenness, etc. In addition, since the polarization switch composed of liquid crystal elements can be controlled and converted by the polarization control means so that the plurality of sets of linearly polarized light are in phase, the polarization beam splitter can efficiently perform spectroscopy, and dust, scratches, unevenness, etc. Therefore, it is possible to construct an efficient and reliable automatic wrinkle inspection device, automatic wrinkle sorting device, and the like with a single polarization selective imaging device.

  In addition, video signals can be sent to internal or external automatic flaw inspection devices, automatic flaw sorting devices, etc., and at the same time, video signals that are easy to detect dust, scratches, unevenness, etc. can be monitored directly on the video monitor as fist images, Visual confirmation of dust, scratches, unevenness, etc. of the subject can be made more reliably.

  In addition, a video that is used to select and control a plurality of linearly polarized light most suitable for inspection of dust, scratches, unevenness, etc., irradiate the subject, photoelectrically convert the reflected light to generate a video signal, and compare the video signal Since it has a signal processing means, it is not necessary to visually inspect for dust, scratches, unevenness, etc., and it can be automated, has high detection accuracy, and builds a high-quality automatic soot inspection device, automatic soot sorting device, etc. be able to.

  Furthermore, since the polarization control unit can control the linearly polarized light generating unit and the polarization switch for each frame in synchronization with the driving unit for the image sensor, for example, for each frame photoelectrically converted by the image sensor. If you output multiple sets of polarization direction video signals, one set with two waves, it is a progressive scan method suitable for computer processing, and it can compare video signals at high speed and at the same time has no flickering and excellent vertical resolution. The video signal of the recorded image can be supplied to the video monitor.

4). According to the invention of claim 4 of the present invention,
In addition to the effect of the third aspect, if the object is irradiated with a plurality of sets of linearly polarized light, which is one set of two polarization directions whose polarization directions are orthogonal to each other, which is most suitable for inspection of dust, scratches, unevenness, etc. The optical image of each polarization direction is photoelectrically converted by an image sensor to generate a video signal, which can be output as the most suitable video signal for detection of dust, scratches, unevenness, etc. Efficient and reliable automatic wrinkle inspection device, automatic wrinkle sorting device and the like can be constructed.

5). According to the invention of claim 5 of the present invention,
In addition to the effects of the first to fourth aspects, the linearly polarized light generating means includes a light source and a plurality of liquid crystal elements that can control the orientation of the polarization direction by the polarization control means.
Select and control multiple linear polarizations that are most suitable for inspection of dust, scratches, unevenness, etc., and arbitrarily set them so that the subject can be irradiated, or azimuths of polarization directions that are most suitable for inspection of dust, scratches, unevenness, etc. Multiple sets of linearly polarized light, one set of two waves with orthogonal polarization directions, can be arbitrarily set, and if an object is irradiated with the linearly polarized light, an optical image of each polarization direction is photoelectrically converted by an image sensor and a video signal Can be output as a video signal most suitable for detection of dust, scratches, unevenness, etc., so a single polarization-selective imaging device has high detection accuracy of dust, scratches, unevenness, etc., high quality, and It is possible to construct an automatic wrinkle inspection device, an automatic wrinkle sorting device, etc. that can respond immediately to any subject.

6). According to the invention of claim 6 of the present invention,
In addition to the effects of the first to fourth aspects, the linearly polarized light generating means includes a plurality of light sources that can be controlled by the polarization control means and a plurality of polarizing filters having different polarization directions. Select a light source equipped with a polarizing filter so that the subject can select and control a plurality of linearly polarized light that is most suitable for inspection of unevenness, etc., or the polarization directions of each other that are most suitable for inspection of dust, scratches, unevenness, etc. If a light source equipped with a polarization filter is selected so that a plurality of sets of linearly polarized light can be obtained by two waves with two directions of polarization orthogonal to each other, and the object is irradiated with the linearly polarized light, the optical in each polarization direction can be obtained. An image is photoelectrically converted by an image sensor to generate a video signal that can be output as a video signal most suitable for detection of dust, scratches, unevenness, etc., so a single polarization-selective imaging device can be used for dust, scratches, unevenness, etc. Detection Degree is high, a high-quality and low-cost automatic flaw inspection device, it can be constructed automatic flaw sorting device.

7). According to the invention of claim 7 of the present invention,
In addition to the effects of the third to sixth aspects, the polarization control means includes a pair of linearly polarized light in the two waves, linearly polarized light having a vibration surface horizontal to the polarization beam splitter incident surface, and the polarized beam splitter. Since the polarization switch is controlled so as to be linearly polarized light having a vibration plane perpendicular to the incident surface, the polarization beam splitter can efficiently separate P-polarized light and S-polarized light, and pick up optical images of the respective polarization directions. A video signal is generated by photoelectric conversion with the element and can be output as the most suitable video signal for detection of dust, scratches, unevenness, etc., so a single polarization selective imaging device is efficient and automatic with high detection accuracy A wrinkle inspection device, an automatic wrinkle sorting device, etc. can be constructed.

8). According to the invention of claim 8 of the present invention,
In addition to the effects of the first to seventh aspects, a plurality of linearly polarized light most suitable for inspection of dust, scratches, unevenness, and the like are selected and controlled to irradiate the subject, and a video signal is generated by photoelectrically converting the reflected light. Since it has video signal processing means that detects and compares video signals that exceed a preset threshold, it can be automated without the need for visual inspection of dust, scratches, unevenness, etc., and has high detection accuracy High-quality automatic wrinkle inspection device, automatic wrinkle sorting device, etc. can be constructed.

9. According to the invention of claim 9 of the present invention,
In addition to the effects of the first to seventh aspects, the video signal processing means includes a video signal generated by the imaging device by reflected light from a reference subject in which the polarization of the reflected light is less likely to change compared to the irradiation light. Since the video signal exceeding the preset threshold value can be detected by comparing the level with the video signal with a plurality of polarization directions generated by the imaging device, the reflected light from the reference subject is less likely to be polarized. A stable reference video signal can be obtained, and level comparison with this reference video signal can be automated without the need for visual inspection of dust, scratches, unevenness, etc. An automatic soot inspection device, an automatic soot sorting device, etc. can be constructed.

10. According to the invention of claim 10 of the present invention,
In addition to the effects of the first to ninth aspects, since the video signal processing means can output an alarm signal when detecting a video signal exceeding the preset threshold value, for example, a warning signal to an inspection worker. Or an alarm signal can be used as a signal for automatic discharge of a specimen having dust, scratches, unevenness, or the like.

The best mode for carrying out the present invention will be described in detail with reference to the drawings.
FIG. 1 is an explanatory diagram of a polarization-selective imaging device using linearly polarized light generating means for selectively controlling a plurality of linearly polarized light and irradiating a subject, and FIG. 2 is a set of two waves of the embodiment of the present invention. FIG. 3 is an explanatory diagram of a polarization-selective imaging device that uses linearly polarized light generating means for selectively controlling a plurality of sets of linearly polarized light and irradiating a subject. FIG. 3 shows two sets of linearly polarized light that are one set of two waves according to the embodiment of the present invention. FIG. 4 is a diagram for explaining the operation of the first frame of the reflected light from the subject irradiated by the generating means and the polarization switch, and FIG. 4 shows the subject irradiated by two sets of linearly polarized light generating means, one set of two waves in the embodiment of the invention. FIG. 7 is an explanatory diagram of the operation of the second frame of the reflected light from the light and the polarization switch.

  In FIG. 1, the polarization-selective imaging device 101 includes a light source 2 on which polarization filters 2 a and 2 b are mounted in order to obtain linearly polarized light A and B of two reflected light beams having different polarization directions with respect to a subject 12. A linearly polarized light illuminating means comprising a linearly polarized light generating means 2 that selectively irradiates “2” alternately in a time period, and an optical image obtained by photoelectrically converting the reflected light from the subject 12 through the lens 3 to form an image A CCD (imaging device) 1 and a CCD driving means 10 for generating signals, and a video signal processing for comparing the video signals generated by the CCD 1 with two reflected light beams having different polarization directions and detecting the level difference Synchronizing with the means 6, the video signal output terminal 7, the alarm signal output terminal 8, the monitor video signal output terminal 9, and the CCD driving means 10, the linearly polarized light is generated every frame. It is composed of a polarization controller 11 capable of controlling the formation unit 2.

  The polarization control means 11 drives the linearly polarized light generation means 2 in synchronism with the CCD drive means 10, selects the light sources 2 'and 2 "for each frame, and irradiates the subject 12 to be inspected.

  A polarizing filter provided with a polarizing film or the like on the front surface of the light source 2 ′, which has a plane of vibration that is horizontal with respect to the direction of irradiation of the subject 12 to be inspected and that can obtain reflected light of linearly polarized light A at an orientation of 0 ° in the polarization direction. The light source 2 'is turned on in the first frame by the polarization control means 11, and the reflected light of linearly polarized light A is obtained from the subject 12 by irradiating the subject 12 via the polarizing filter 2a.

  Similarly, a polarization film or the like on which the reflected light of the linearly polarized light B is obtained on the front surface of the light source 2 ″ with a azimuth of 90 ° in the polarization direction having a vibration plane perpendicular to the irradiation direction of the subject 12 is attached. A filter 2b is provided, the light source 2 "is turned on in the next second frame by the polarization control means 11, and the reflected light of linearly polarized light B is obtained from the subject 12 by irradiating the subject 12 through the polarizing filter 2b. ing.

  The reflected lights of the linearly polarized light A and B are imaged on the photoelectric surface of the CCD 1 by the lens 3, and the photoelectrically converted video signal is input to the video signal processing means 6, and the video signals of the first frame and the second frame are respectively Is stored in a frame memory (not shown).

  Compares the levels of two video signals read from the frame memory, or the reflected light is less likely to change compared to the irradiated light, for example, reflected light from a reference object (not shown) with a mirror-finished metal surface The level of the reference video signal generated by the CCD 1 and the video signal of the plurality of polarization directions generated by the CCD 1 is compared, and a video signal exceeding a preset threshold is detected by a known circuit technique. For example, it can be used as a warning signal for an inspection worker, or as an alarm signal for automatic discharge of a specimen having dust, scratches, unevenness, or the like.

  The orientation of the polarization direction shown in the first embodiment is an example, and is not limited to the numerical value. The linearly polarized light A and B that are reflected light from the subject 12 are 15 ° to 90 °, respectively. A linear polarization with an interval may be used, and a polarization direction that is most suitable for measurement of specimen dust, scratches, unevenness, etc., and that is most likely to emphasize the phenomenon of specimen dust, scratches, unevenness, etc. It is preferable to obtain a video signal by photoelectrically converting an optical image formed on the image sensor by performing combination selection control in the azimuth direction.

  Further, the polarizing filters 2a and 2b using the polarizing film or the like of the linearly polarized light generating means 2 are not limited to the polarizing film or the like, but may be a polarizing plate using a liquid crystal element in which the direction of the polarization direction can be arbitrarily set by voltage control. Good.

  Further, since the reflected light from the subject 12 is linearly polarized light in a plurality of polarization directions, a combination of a plurality of light sources and a plurality of polarizing filters may be attached, and the subject may be controlled by being controlled.

  In FIG. 2, the polarization-selective imaging device 102 reflects two sets of linearly polarized light A / B and C / D in which four waves of linearly polarized light A, B, C, and D having different polarization directions are set as two sets. From the linearly polarized light generating means 2 that alternately selects the light sources 2 ′ and 2 ″ with two sets of polarizing filters 2a / 2b and 2c / 2d, respectively, to irradiate the subject 12 in order to obtain light. The linearly polarized illumination means, the polarization beam splitter 5 that splits the reflected light incident from the subject 12 through the lens 3 in two directions, and the optical images that are split in two directions by the polarization beam splitter 5 are photoelectrically converted. CCDs 1 and 2 and their CCD driving means 10 for generating video signals by conversion, video signal processing means 6 for comparing the video signals generated from the CCDs 1 and 2 and detecting their level difference, and video signal output terminal 7 and alarm signal Two sets of linearly polarized light A / B, C /, which are arranged between an output terminal 8, a monitor video signal output terminal 9, the lens 3 and the polarization beam splitter 5 and made up of two waves of the reflected light. In synchronization with the CCD driving means 10 and a polarization switch 4 composed of a liquid crystal element that selects D with a certain period of time and controls the two sets of linearly polarized light A / B and C / D to be in phase. The linearly polarized light generating means 2 and the polarization switch 4 that can control the polarization switch 4 for each frame.

  The polarization control means 11 drives the linearly polarized light generation means 2 in synchronism with the CCD drive means 10, selects the light sources 2 'and 2 "for each frame, and irradiates the subject 12 to be inspected.

  On the front surface of the light source 2 ′, a polarizing film or the like that can obtain reflected light of linearly polarized light A at an azimuth of 0 ° in the polarization direction having a vibration surface that is horizontal (0 °) with respect to the irradiation direction of the subject 12 to be inspected. A polarizing filter equipped with a polarizing filter 2a that is mounted, a polarizing film that has a vibration plane perpendicular to the irradiation direction of the subject 12 (90 °), and that can obtain reflected light of linearly polarized light B at 90 ° in the polarization direction. When the light source 2 'is turned on, the subject 12 is irradiated so that two sets of reflected light linearly polarized light A / B are obtained simultaneously.

  Similarly, on the front surface of the light source 2 ″, a polarizing film or the like that obtains reflected light of linearly polarized light C at an azimuth of 45 ° in the polarization direction having a vibration surface of 45 ° with respect to the irradiation direction of the subject 12 to be inspected. A polarizing filter 2c mounted and a polarizing filter 2d mounted with a polarizing film or the like that obtains reflected light of linearly polarized light D at an orientation of 135 ° in the polarization direction having a vibration surface of 135 ° with respect to the irradiation direction of the subject 12 are arranged. When the light source 2 ″ is turned on, the subject 12 is irradiated so that linearly polarized light C / D of reflected light as a set of two waves can be obtained simultaneously.

  The reflected light of linearly polarized light A / B and C / D is imaged by the lens 3 on the photoelectric surfaces of the CCDs 1 and 2 via the polarization switch 4 and the polarization beam splitter 5, and the photoelectrically converted video signal is a video signal processing means. 6, the video signal of the first frame is stored in a frame memory (not shown), and similarly, the video signal of the second frame is also stored in a frame memory (not shown).

  3 and 4 schematically show the detailed structure of the polarization switch 4 composed of a liquid crystal element. The polarization switch 4 includes a pair of transparent substrates 4b and 4c, and a liquid crystal layer 4a sandwiched between the transparent substrates 4b and 4c.

  Transparent electrodes are formed on the opposing main surfaces of the transparent substrates 4b and 4c, and are connected to the polarization control means 11. For the liquid crystal layer 4a, for example, STN (Super Twisted Nematic) type liquid crystal is used.

  As is known, the polarization switch 4 controls the voltage applied between the transparent substrates 4b and 4c and the liquid crystal layer 4a to change the optical rotation of the liquid crystal molecules of the liquid crystal layer 4a, thereby polarizing the linearly polarized light incident thereon. The state can be changed.

  The object 12 is irradiated by the linearly polarized light generating means 2, and the polarized beam is used so that a pair of linearly polarized light A / B and C / D is in phase with the polarization switch 4 by two waves as reflected light. Linearly polarized light E having a horizontal (0 ° / P-polarized) vibrating surface on the entrance surface of the splitter 5 and linearly polarized light E having a vibrating surface perpendicular (90 ° / S-polarized) to the incident surface of the polarizing beam splitter 5. Is converted to

  In FIG. 3, the polarization switch 4 is voltage controlled by the polarization control means 11 so that its optical rotation is lost. Therefore, the linearly polarized light generating means 2 is controlled in synchronization with the CCD driving means 10 so that the linearly polarized light A / B is selected in the first frame, and the linearly polarized light A / B passes through the lens 3 and goes to the polarization switch 4. Make it incident.

  A pair of linearly polarized light A (0 °) and linearly polarized light B (90 °) of two waves, which are reflected light from the subject 12, is lost in optical rotation when incident on the polarization switch 4. The linearly polarized light E that is transmitted through the layer 4a without being twisted and transmitted through the polarization switch 4 is in a state in which the direction of the polarization direction of the incident light is maintained.

  Next, in FIG. 4, the polarization switch 4 is in a state in which voltage control is performed by the polarization control means 11 so that the optical rotation is activated. Therefore, the linearly polarized light generating means 2 is controlled in synchronization with the CCD driving means 10 so that the linearly polarized light C / D is selected in the second frame, and the linearly polarized light C / D passes through the lens 3 and goes to the polarization switch 4. Make it incident.

  When a pair of linearly polarized light C (45 °) and linearly polarized light D (135 °) of two waves, which are reflected light from the subject 12, is incident on the polarization switch 4, the polarization switch 4 rotates at −45 °. In the liquid crystal layer 4a, the linearly polarized light C / D is subjected to a so-called twist, and the linearly polarized light E transmitted through the polarization switch 4 is in phase with the first frame. Linearly polarized light E having a horizontal (0 ° / P-polarized) vibrating surface on the beam splitter 5 incident surface and linearly polarized light E having a vertical (90 ° / S-polarized) vibrating surface on the polarized beam splitter 5 incident surface. Is converted as follows.

  Therefore, in FIG. 2, the linearly polarized light E converted into the same phase is incident on the polarization beam splitter 5, and the linearly polarized light E having a horizontal (0 °) vibration plane on the incident surface of the polarization beam splitter 5 travels straight through. , P-polarized light forms an image on the CCD 2 photoelectric surface, and linearly polarized light E having a vibration plane perpendicular (90 °) to the incident surface of the polarizing beam splitter 5 is reflected by the reflecting surface 5 ′ of the polarizing beam splitter 5 and is converted into S-polarized light. An image is formed on the CCD1 photocathode.

  The orientation of the polarization direction of the linearly polarized light generating means 2 shown in the second embodiment is an example, and is not limited to the numerical value. Also, one set of two waves as reflected light from the subject 12 is used. The two sets of linearly polarized light A, B, C, and D need only be linearly polarized light at intervals of 15 ° to 90 °, respectively, and sample dust that is most suitable for measurement of sample dust, scratches, unevenness, etc. The optical image formed on the imaging device is selected and controlled by combining and controlling the four types of representative polarization directions in which the phenomena such as scratches and unevenness are most emphasized in the orientations of the polarization directions of A⊥B and C⊥D. It is preferable to convert to obtain a video signal.

  Further, the polarizing filters 2a, 2b, 2c, and 2d using the polarizing film of the linearly polarized light generating means 2 are not limited to the polarizing film, but use a liquid crystal element in which the direction of the polarization direction can be arbitrarily set by voltage control. It may be a polarizing plate.

  Further, in order to obtain a plurality of sets of linearly polarized light that is a set of two waves that are reflected from the subject 12, a plurality of light sources and a plurality of polarizing filters are mounted in combination, and polarized light that is a set of two waves. The subject may be irradiated by selecting and controlling with a plurality of sets of light sources having different azimuth directions.

  The optical images formed on the CCDs 1 and 2 are photoelectrically converted and input to the video signal processing means 6. In the video signal processing means 6, two or four video signals which are controlled in phase by the polarization switch 4 and split into S-polarized light and P-polarized light by the polarizing beam splitter 5 and photoelectrically converted by the CCDs 1 and 2 are generated. Is temporarily stored in the frame memory (not shown), and the levels of two or four video signals read from the respective frame memories are compared, or the polarization of the reflected light is less likely to change compared to the irradiation light. For example, a standard video signal generated by photoelectric conversion by the CCD 1 or 2 by reflected light from a reference object (not shown) having a mirror-finished metal surface and linear polarization controlled in phase by the polarization switch 4 are photoelectrically converted. The level of each video signal generated by the CCDs 1 and 2 is compared, and a video signal exceeding a preset threshold is detected by a known circuit technique. , For example, to a warning signal to the test operator can be used as an alarm signal dirt, scratches, as an automatic discharge signal analyte of irregularity.

  Even in the case of a plurality of sets of linearly polarized light generating means, one set of the two waves, the video signal processing means 6 may be processed similarly.

  In the above embodiment, the video signal may be output to the outside from the video output terminal 7 as a time-series signal in frame order. Furthermore, a video signal exceeding a preset threshold is detected and output from the video output terminal 7 to the outside. At the same time, an alarm signal is added to the video signal, for example, a blinking cursor signal or a character signal. It can be output to the output terminal 8.

  Furthermore, the video signal processing means 6 may perform image processing for displaying two or four or more video signals in two or more parts on the video monitor screen, and output them to the monitor video signal output terminal 9. For example, it is possible to monitor a video signal with a plurality of polarization directions, which is converted into linearly polarized light by controlling the linearly polarized light generating means 2 with a time period, with a single video monitor.

  The linearly polarized light generating means 2 may be a linearly polarized light generating means 2 provided with a light source capable of emitting subject illumination light in any one of the visible light band and the invisible light band. A type polarization switch may be used.

  As described above, a polarization selection type that combines any one band light in the visible light band or invisible light band and the linearly polarized light generating means 2 that selectively controls a plurality of linearly polarized lights having different polarization directions and irradiates the subject. If the imaging devices 101 and 102 are used, they can be used more reliably for inspection of dust, scratches, unevenness, and the like.

  Here, the CCDs 1 and 2 may be two-dimensional solid-state image sensors or one-dimensional solid-state image sensors. Moreover, it is not limited to CCD, and other solid-state image sensors or tube-type image sensors may be used.

  In the description of the above embodiments, a moire-preventing crystal low-pass filter disposed before and after the polarization beam splitter 5 when used in combination with a CCD, a correlated double sampling circuit necessary for a CCD signal amplification circuit, and a gamma correction circuit. However, known techniques that are normally required for a solid-state imaging device camera but are not involved in the present invention are omitted in the description and the drawings.

  With one polarization selective imaging device, it is possible to reliably and easily find dust, scratches, unevenness, and the like of a subject by using a linearly polarized light generating unit that selectively controls a plurality of linearly polarized light having different polarization directions and irradiates the subject. Therefore, it can be used for measuring devices such as dust, scratches, and unevenness, inspection devices, and monitoring devices.

Explanatory drawing of the polarization selective imaging device using the linearly polarized light generating means for selectively controlling a plurality of linearly polarized light and irradiating the subject in the embodiment of the present invention Explanatory drawing of the polarization-selection type imaging apparatus using the linearly polarized light generating means for selectively controlling a plurality of sets of linearly polarized light, which is a set of 2 waves, and irradiating the subject. Explanation of the operation of the first frame of the reflected light from the subject irradiated by the two sets of linearly polarized light generating means, which is one set of two waves in the embodiment of the invention, and the polarization switch The operation explanatory diagram of the second frame of the reflected light from the object irradiated by the two sets of linearly polarized light generating means which are one set of two waves of the embodiment of the invention and the polarization switch

Explanation of symbols

101, 102: Polarization selective imaging device 2: Linearly polarized light generating means 2a, 2b, 2c, 2d: Polarizing filter 2 ′, 2 ″: Light source 3: Lens 4: Polarization switch 4a: Liquid crystal layer 4b, 4c: Transparent substrate 5 : Polarized beam splitter 5 'reflecting surface 6: Video signal processing means 7: Video signal output terminal 8: Alarm signal output terminal 9: Monitor video signal output terminal 10: CCD drive means 11: Polarization control means 12: Subject CCD1, CCD2: Image sensors A, B, C, D, E: Linearly polarized light

Claims (10)

An image obtained by photoelectrically converting a linearly polarized light illumination means comprising linearly polarized light generating means for generating a plurality of linearly polarized lights having different polarization directions, and an optical image formed by imaging the reflected light from the irradiation of the linearly polarized light on the subject through a lens. An image pickup device that generates a signal and a driving unit thereof, a video signal processing unit that performs a comparison process on a video signal generated from the image pickup device, and a polarization control unit that controls the linearly polarized light generation unit,
The polarization selection type imaging apparatus, wherein the polarization control means controls the linearly polarized light generation means for each frame in synchronism with the driving means of the imaging device.   2. The polarization-selective imaging device according to claim 1, wherein the linearly polarized light generating unit irradiates the subject with linearly polarized light having an interval of 15 ° to 90 ° with the plurality of linearly polarized light having different polarization directions. . Linearly polarized illumination means comprising linearly polarized light generating means for generating a plurality of sets of combinations of the same narrow angle and different polarization directions among a plurality of linearly polarized lights having different polarization directions, and incident via a lens A polarizing beam splitter that splits the reflected light generated by irradiating the subject with the linearly polarized light in two directions, and an image sensor that photoelectrically converts each optical image split in two directions by the polarizing beam splitter to generate a video signal. And a driving means thereof, a video signal processing means for comparing video signals generated from the image sensor, a plurality of sets arranged between the lens and the polarization beam splitter, and a set of two reflected light waves A polarization switch composed of a liquid crystal element that selects a set of linearly polarized light at regular time intervals and controls the plurality of sets of linearly polarized light to be in phase; and the linearly polarized light generating means; Comprising a polarization control means for controlling the polarization switch, the,
The polarization selection type imaging apparatus, wherein the polarization control unit controls the linearly polarized light generation unit and the polarization switch for each frame in synchronization with the driving unit of the imaging device.   The linearly polarized light generating means converts the set of two linearly polarized light into linearly polarized light whose directions of polarization are orthogonal to each other and irradiates the subject with a plurality of sets of linearly polarized light having different directions of polarization directions. The polarization-selective imaging device according to claim 3.   5. The polarized light according to claim 1, wherein the linearly polarized light generating unit includes a light source and a plurality of liquid crystal elements capable of controlling the direction of polarization direction by the polarization control unit. Selective imaging device.   The linearly polarized light generating unit includes a plurality of light sources that can be selectively controlled by the polarization control unit, and a plurality of polarizing filters having different polarization directions. The polarization selective imaging device described.   The polarization control means includes a pair of linearly polarized light beams of the two waves, linearly polarized light having a vibration surface horizontal to the polarization beam splitter incident surface, and linearly polarized light having a vibration surface perpendicular to the polarization beam splitter incident surface. The polarization-selective imaging apparatus according to claim 3, wherein the polarization switch is controlled so as to be.   The video signal processing means can detect video signals exceeding a preset threshold by comparing video signal levels generated by the imaging device according to a plurality of polarization directions. 2. A polarization-selective imaging device according to item 1.   The video signal processing means includes: a video signal generated by the image sensor by reflected light from a reference subject, the polarization of the reflected light being less likely to change compared to the irradiation light, and a plurality of polarization directions generated by the image sensor The polarization selective imaging device according to any one of claims 1 to 7, wherein a video signal exceeding a preset threshold value can be detected by comparing a level with a video signal obtained by the method. 10. The polarization selective imaging apparatus according to claim 1, wherein an alarm signal can be output when the video signal processing means detects a video signal that exceeds the preset threshold value. 11.