JP2013036908A - Observation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an observation device capable of accurately detect minute foreign materials adhered to a surface of a transparent object and minute defects on the surface of the transparent object.SOLUTION: The observation device for surface includes a light source device, a polarization conversion device, a half-mirror, a lens, a light receiving module, a circuit board, a housing, a processor, etc. The light receiving module includes a polarization filter 151, a micro lens array 153, an image sensor, etc. A gap Dint between a +Z side surface of the polarization filter 151 and the micro lens array 153 are set to be a lens pitch Pml or smaller in the micro lens array 153.

Description

  The present invention relates to an observation apparatus, and more particularly to an observation apparatus that optically observes the surface of an object.

  In the manufacturing site of industrial products, ensuring that no foreign matter is attached to the object and that the object is not scratched is to carry out the subsequent processes as scheduled, and to produce the desired product with a high yield. is important.

  Therefore, in the production line, for example, light reflected by an object is received by an image sensor such as a CCD camera, and it is detected by an image processing whether a foreign object is attached to the object or whether the object is flawed. A detection device is used.

  By the way, in the above detection device, it is difficult to detect whether a transparent IC chip, glass, film or the like has a foreign object on the surface or whether an object has a flaw due to the influence of the base. It was.

  Therefore, various devices for detecting whether or not the surface of a transparent object is healthy have been proposed.

  For example, Patent Document 1 discloses an inspection device that detects a foreign matter or a defect present on the surface and inside of a transparent solid. The inspection apparatus includes a white light surface light source, a first polarizing plate that transmits light from the surface light source, and the first polarizing plate that is irradiated to the object to be inspected and transmitted through the object to be inspected. A second polarizing plate that receives and transmits the transmitted light, and has a function of detecting a foreign substance or a defect based on unevenness in intensity or color of light passing through the second polarizing plate.

  By the way, in recent years, the demand for the soundness of the member surface has become stricter, and the attachment of minute foreign matters of about 1 μm has become unacceptable.

  However, in the inspection apparatus disclosed in Patent Document 1, it is difficult to detect a minute foreign substance of about 1 μm.

  The present invention is an observation apparatus for optically observing the surface of an object, and is disposed on an optical path of light passing through the object and an optical path of light passing through the lens. A polarizing filter; a microlens array disposed on an optical path of light that has passed through the polarizing filter; and an image sensor that is disposed on an optical path of light that passes through the microlens array and includes a plurality of light receiving units. In the observation device, an interval between the polarizing filter and the microlens array is equal to or less than a lens pitch in the microlens array.

  According to the observation apparatus of the present invention, the light passing through the object is incident on the microlens without interference, and the foreign matter adhering to the surface of the transparent object and the surface defect of the transparent object are accurately observed. Can do.

It is a figure for demonstrating the structure of the surface observation apparatus which concerns on one Embodiment of this invention. It is a figure for demonstrating the light source device in FIG. It is a figure for demonstrating the polarization converter in FIG. 4A and 4B are diagrams for explaining the movement of the holding member in the polarization conversion device. It is a figure for demonstrating the polarizing plate 111 in a polarization converter. It is a figure for demonstrating the polarizing plate 112 in a polarization converter. It is FIG. (1) for demonstrating the state in which the light reception module is mounted in the circuit board. It is FIG. (2) for demonstrating the state in which the light reception module is mounted in the circuit board. It is a figure for demonstrating the structure of a light reception module. It is a figure for demonstrating the polarization pattern of a polarizing film. It is a figure for demonstrating the positional relationship of a polarizing film and a mylo lens array. It is FIG. (1) for demonstrating the observation result when observing the surface of a glass plate. It is FIG. (2) for demonstrating the observation result when observing the surface of a glass plate. It is a figure for demonstrating the inconvenience when the space | interval of a polarizing film and a mylo lens array is large. It is a figure for demonstrating the image of the foreign material observed at the time of FIG. It is a figure for demonstrating the advantage of this embodiment. It is the figure which expanded a part of FIG. It is a figure for demonstrating the image of the foreign material observed at the time of FIG. It is a figure for demonstrating the image of the foreign material observed when the light beam for illumination is incident on the surface of a target object diagonally. It is a figure for demonstrating the modification of a polarization pattern. It is the figure which expanded a part of FIG. It is a figure for demonstrating the light reception module using the modification of the polarization pattern of FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of a surface observation apparatus 10 according to an embodiment.

  The surface observation device 10 includes a light source device 100, a polarization conversion device 110, a half mirror 120, a lens 130, a light receiving module 150, a circuit board 170, a housing 180, a processing device 200, an input device 210, a display device 220, and an HDD device 230. And a horizontal driving device 240.

  Here, the observed object 300 is a transparent plate member. The object 300 is placed on the transport belt 400 and transported to a predetermined position during surface observation.

  In the present specification, the direction orthogonal to the surface of the object 300 is defined as the Z-axis direction, and the directions orthogonal to each other within the plane orthogonal to the Z-axis direction are defined as the X-axis direction and the Y-axis direction.

  Here, the surface observation apparatus 10 is disposed on the + Z side of the object 300 and observes the + Z side surface of the object 300. Hereinafter, the + Z side surface of the target object 300 is also referred to as a “target surface”.

  As shown in FIG. 2 as an example, the light source device 100 includes a light source 101 including LEDs, and a collimating lens 102 that makes a light beam emitted from the light source 101 substantially parallel.

  The light source 101 is turned on and off by the processing device 200.

  The light source device 100 emits a light beam in the −X direction.

  The polarization conversion device 110 is arranged on the −X side of the light source device 100 and holds two polarizing plates (111, 112) and the two polarizing plates (111, 112) as shown in FIG. 3 as an example. The holding member 113 and a drive mechanism that moves the holding member 113 in the Z-axis direction are provided.

  The drive mechanism includes a screw member screwed into a “female screw portion” formed in the holding member 113, a first gear attached to the −Z side end of the screw member, and a first gear meshed with the first gear. A shaft including two gears, a stepping motor 115 for rotating the shaft, and the like are included. The stepping motor 115 is controlled by the processing device 200.

  Therefore, when the stepping motor 115 is driven, the positions of the two polarizing plates (111, 112) in the Z-axis direction change.

  Here, as shown in FIG. 4A, the processing device 200 has a first position where the light beam from the light source device 100 passes through the substantially central portion of the polarizing plate 111, and as shown in FIG. 4B. In addition, the stepping motor 115 is controlled by selecting one of the second positions where the light flux from the light source device 100 passes through the substantially central portion of the polarizing plate 112.

  The polarizing plate 111 transmits linearly polarized light whose polarization direction is orthogonal to the Z-axis direction, and the polarizing plate 112 transmits linearly polarized light whose polarization direction is parallel to the Z-axis direction (see FIGS. 5 and 6).

  The half mirror 120 is disposed on the −X side of the polarization conversion device 110 and reflects about half of the light beam emitted from the polarization conversion device 110 in the −Z direction.

  The lens 130 is disposed on the −Z side of the half mirror 120 and condenses the light beam reflected by the half mirror 120 in the vicinity of the target surface. Here, a condensing lens with a magnification of 1000 times is used as the lens 130.

  In place of the lens 130, a lens system including a plurality of lenses may be used. For example, a lens having a magnification of 100 may be disposed on the −Z side of the half mirror 120, and a lens having a magnification of 10 may be disposed between the half mirror 120 and the light receiving module 150.

  Here, the light beam reflected by the half mirror 120 illuminates the target surface. Then, most of the light beam reflected by the target surface passes through the lens 130 again and enters the half mirror 120.

  About half of the light beam incident on the half mirror 120 passes through the half mirror 120.

  The light receiving module 150 is disposed on the optical path of the light beam that has passed through the half mirror 120.

  The light receiving module 150 is mounted on the surface on the −Z side of the circuit board 170 as shown in FIGS. 7 and 8 as an example.

  As shown in FIG. 9 as an example, the light receiving module 150 includes a polarizing filter 151, a microlens array 153, an image sensor 155, and the like, which are integrated.

  In the polarizing filter 151, a polarizing pattern 152 is formed on the + Z side surface of a transparent plate member. Here, as an example, as shown in FIG. 10, the polarization pattern 152 includes two kinds of minute patterns (152a, 152b) arranged in a matrix. Each minute pattern has a quadrangular shape of the same size, and here, dx = dy = 6 μm.

  The minute pattern 152a transmits linearly polarized light whose polarization direction is orthogonal to the X-axis direction, and the minute pattern 152b transmits linearly polarized light whose polarization direction is parallel to the X-axis direction.

  Micropatterns 152b are arranged on the + X side, -X side, + Y side, and -Y side of the micropattern 152a, and the micropatterns 152a are arranged on the + X side, -X side, + Y side, and -Y side of the micropattern 152b. Is arranged.

  The microlens array 153 is disposed on the + Z side of the polarizing filter 151. The gap Dint (see FIG. 11) between the + Z side surface of the polarizing filter 151 and the microlens array 153 is set to be equal to or smaller than the lens pitch Pml (see FIG. 11) in the microlens array 153. Specifically, Pml = 6 μm and Dint = 2 μm.

  The microlens array 153 condenses the light beam that has passed through the polarizing filter 151.

  The image sensor 155 is disposed on the + Z side of the microlens array 153 and has a plurality of light receiving regions that receive light beams that have passed through the microlens array 153. Here, each light receiving region is a substantially square having a side length of 6 μm. That is, there is a one-to-one correspondence between the microlens and the light receiving area. Therefore, the gap Dint is equal to or smaller than the size of the light receiving area. Hereinafter, for the sake of convenience, the light receiving area of the image sensor 155 is also referred to as a “pixel”.

  Here, the image sensor 155 can receive reflected light from a region having a diameter of 0.178 mm on the target surface.

  Light reception information of the image sensor 155 is output to the processing device 200. The image sensor 155 outputs data corresponding to the density of 256 gradations for each pixel.

  The light source device 100, the polarization conversion device 110, the half mirror 120, the lens 130, the light receiving module 150, and the circuit board 170 are attached to the housing 180.

  The horizontal driving device 240 moves the housing 180 within the XY plane according to an instruction from the processing device 200. The position information of the housing 180 is notified from the horizontal driving device 240 to the processing device 200. Here, the optical axis position of the lens 130 in the XY plane is output from the horizontal driving device 240 as position information of the housing 180 (see FIG. 1).

  The processing device 200 includes a CPU, a ROM described in a program written in a code decodable by the CPU and various data used when executing the program, a RAM as a working memory, and a network. And a communication control device for performing information communication with other devices.

  The input device 210 includes, for example, at least one input medium (not shown) of a keyboard, a mouse, a tablet, a light pen, a touch panel, and the like, and notifies the CPU of various information input by an operator. Note that information from the input medium may be input in a wireless manner.

  The display device 220 includes a display unit (not shown) using, for example, a CRT, a liquid crystal display (LCD), a plasma display panel (PDP), and the like, and displays various information instructed by the CPU.

  An example of an integrated display device 220 and input device 210 is an LCD with a touch panel.

  The HDD device 230 includes a hard disk and a drive device for driving the hard disk.

  Next, the operation of the processing apparatus 200 will be described.

(1) When it is confirmed from the sensor output (not shown) that the object 300 has been conveyed to the surface observation start position, the light source 101 is turned on.
(2) The stepping motor 115 is controlled so that the light beam from the light source device 100 passes through the substantially central portion of the polarizing plate 111.
(3) The output of the image sensor 155 is stored in the RAM together with the position information of the housing 180 as a first polarization image.
(4) The stepping motor 115 is controlled so that the light beam from the light source device 100 passes through the substantially central portion of the polarizing plate 112.
(5) The output of the image sensor 155 is stored in the RAM together with the position information of the housing 180 as a second polarization image.
(6) The housing 180 is moved to the next observation position via the horizontal driving device 240.
(7) Perform (2) to (5) above.
(8) Repeat the above (6) and (7) until the observation at all the observation positions is completed.
(9) When the observation at all the observation positions is completed, the first polarization image and the second polarization image are synthesized for each position information of the housing 180. The synthesized image is displayed on the input device 210.
(10) For each position information of the housing 180, the presence / absence of a foreign object and a defect is determined based on the synthesis result, and the determination result is stored in the RAM together with the position information of the housing 180.
(11) If there is at least one of a foreign substance and a defect, its shape and size are obtained and stored in the RAM together with the position information of the housing 180.
(12) If there is a foreign object, it is determined from the gradation of the image whether the foreign object is a metal, resin, or ceramic, and is stored in the RAM together with the position information of the housing 180. The relationship between the gradation of the image and the material is obtained in advance and stored in the ROM.
(13) If there is at least one of the foreign matter and the defect, the positional information of the foreign matter and the defect in the object 300 is obtained from the position information of the housing 180 and stored in the RAM.
(14) The presence / absence information, shape, size, and material of the foreign object and defect in the object 300, and the positional information of the foreign object and defect in the object 300 are displayed on the input device 210 and transmitted to other devices via the network. Notice.
(15) The observation result is stored in the HDD device 230 together with the observation date and time and information (for example, ID number) that can identify the object 300.
(16) Wait for the next object.

  12 and 13 show images of foreign matters adhering to the surface of a transparent glass plate. Both are about 1 μm in size. In this way, the shape can be clearly known even if the foreign matter has a size of about 1 μm.

  For example, if the other device is a determination device for a pass / fail determination step, the determination device is based on the observation result from the processing device 200 and has no foreign matter or a defect, or at least the foreign matter and the defect. Even if there is one, if the shape and size are within the set allowable range, it is determined to be acceptable, and if the shape and size of the foreign matter and defect are not within the allowable range, it is determined to be unacceptable. Further, when the determination device determines that the foreign matter can be removed based on the observation result from the processing device 200, the determination device sends the object to the regeneration processing step.

  Further, for example, if the other apparatus is a cleaning apparatus in the cleaning process, the cleaning apparatus mainly cleans the position where the foreign matter adheres based on the observation result from the processing apparatus 200.

  Thus, by incorporating the surface observation apparatus 10 into the production line, extraction of defective products and extraction of recyclable products can be automated. In addition, an efficient cleaning process is possible. Also, the line speed can be increased. Furthermore, accurate inspection can be performed, and the production yield can be improved.

  Incidentally, if the gap Dint between the + Z side surface of the polarizing filter 151 and the microlens array 153 is larger than the lens pitch Pml, as shown in FIG. 14 as an example, the interfered light beam enters the microlens. In this case, as shown in FIG. 15 as an example, the shape and size of the foreign matter adhering to the target surface is observed in an unclear state.

  On the other hand, in this embodiment, since the gap Dint between the + Z side surface of the polarizing filter 151 and the microlens array 153 is equal to or smaller than the lens pitch Pml, as shown in FIGS. It does not enter the microlens. FIG. 17 is an enlarged view of a part of FIG. In this case, as shown in FIG. 18 as an example, the shape and size of the foreign matter adhering to the target surface is observed in a clear state.

  As described above, according to the surface observation device 10 according to the present embodiment, the surface observation device 10 includes the light source device 100, the polarization conversion device 110, the half mirror 120, the lens 130, the light receiving module 150, the circuit board 170, and the housing. 180, a processing device 200, an input device 210, a display device 220, an HDD device 230, a horizontal driving device 240, and the like.

  The light receiving module 150 includes a polarizing filter 151, a microlens array 153, an image sensor 155, and the like. The gap Dint between the + Z side surface of the polarizing filter 151 and the microlens array 153 is set to be equal to or smaller than the lens pitch Pml in the microlens array 153.

  In this case, it is possible to suppress the light beams incident on the respective microlenses from interfering with each other, and a clear image of foreign matter or defects can be obtained.

  Therefore, according to the surface observation apparatus 10, it is possible to accurately observe minute foreign matters attached to the surface of the transparent object and minute defects on the surface of the transparent object. As a result, even if there is a foreign matter of about 1 μm, the shape, size, and material can be known. Similarly, even if there is a defect of about 1 μm, the shape and size can be known.

  In addition, unlike the inspection apparatus disclosed in Patent Document 1, according to the surface observation apparatus 10, even if the object is placed on an opaque object, a minute foreign matter attached to the surface of the transparent object, In addition, minute defects on the surface of a transparent object can be observed with high accuracy.

  In addition, in a conventional observation apparatus, a lens with a high magnification is required to obtain the shape of a minute foreign matter and a minute defect. In this case, the field of view becomes narrow, and a great deal of time is required to observe the entire surface of the object. In this case, focusing becomes difficult.

  On the other hand, the surface observation apparatus 10 can obtain a clear image without increasing the magnification of the lens so much. Therefore, the entire surface of the object can be observed in a shorter time than conventional. In addition, focusing is easy. That is, the surface of the transparent member can be observed in a non-contact manner at intervals similar to those of normal microscope observation.

  Moreover, in the surface observation apparatus 10, since it illuminates on the surface of a target object by epi-illumination, size reduction of an apparatus can be achieved.

  Further, the surface observation apparatus 10 can obtain a clearer image than before without using expensive parts, and can improve cost performance.

  In the above-described embodiment, the case where the light beam from the light source device 100 is incident from the direction orthogonal to the surface of the object has been described. However, the present invention is not limited to this. The light beam from the light source device 100 may be obliquely incident on the surface of the object. In this case, as shown in FIG. 19 as an example, the three-dimensional shape of a foreign substance or a defect can be known.

  Moreover, in the said embodiment, it may replace with the polarization pattern 152 of the said polarizing filter 151, and may use polarization pattern 152 'shown by FIGS. 20-22 as an example. Here, the symbol d1 in FIG. 21 is the same as the symbol d2, and is set to 6 μm.

  In this case, a total reflection member (for example, a mirror) is placed in advance on the position of the object 300, and the incident light quantity when the polarizing filter 151 is not provided for all the pixels of the image sensor 155 is used as a reference. It is a pixel (referred to as “first pixel group” for convenience) in which the amount of incident light is 50% or more when the light beam passes through the polarizing plate 111, or the light beam from the light source device 100 passes through the polarizing plate 112. It is determined whether the pixel has an incident light quantity of 50% or more (referred to as “second pixel group” for convenience).

  Then, when observing the object 300, the processing device 200 obtains the first polarization image from the outputs of the plurality of pixels belonging to the first pixel group in the step (3), and in the step (5). The second polarization image is obtained from the outputs of a plurality of pixels belonging to the second pixel group.

  In this case, the alignment of the image sensor 155 and the polarizing filter 151 can be simplified as compared with the above embodiment.

  In the above embodiment, the light source 101 may include a plurality of light emitting units.

  Moreover, although the said embodiment demonstrated the case where the polarizing member which moves the holding member 113 to a Z-axis direction and selects the polarizing plate through which the light beam from the light source device 100 passes was selected in the polarization converter 110, it is limited to this. It is not a thing. For example, the polarizing plate through which the light beam from the light source device 100 passes may be selected by moving the holding member 113 in the Y-axis direction or rotating the holding member 113 around an axis parallel to the X-axis direction. One polarizing plate may be rotated about an axis parallel to the X-axis direction. In short, it is only necessary that the polarization direction of the light beam emitted from the polarization conversion device 110 can be selected.

  Moreover, although the said embodiment demonstrated the case where the magnification of the lens 130 was 1000 times, it is not limited to this. A lens with an appropriate magnification can be used according to the required detection accuracy and the size of the foreign matter and defect to be detected. For example, when the size of foreign objects and defects to be detected is large, a low-magnification lens can be used, and a wide field of view can be observed at once. As a result, the time required for observation can be shortened. A lens having a variable magnification may be used.

  Moreover, although the said embodiment demonstrated the case where a microlens and a pixel respond | correspond one to one, it is not limited to this. When the required detection accuracy is not so high, or when the size of foreign objects and defects to be detected is large to some extent, for example, one microlens may be provided for four pixels.

  Moreover, although the said embodiment demonstrated the case where the magnitude | size of 1 pixel was 6 micrometers, it is not limited to this.

  In the above embodiment, the case where the lens pitch Pml is 6 μm and the gap Dint is 2 μm has been described. However, the present invention is not limited to this. In short, it is sufficient that the gap Dint is equal to or smaller than the lens pitch Pml.

  In the above embodiment, the case where the housing 180 is moved when the field of view of the observation target is different has been described. However, the present invention is not limited to this, and the object 300 may be moved.

  Moreover, in the said embodiment, a colored transparent member may be sufficient as the said target object.

  In the above embodiment, an IC chip including a processing circuit may be mounted on the circuit board 170, and at least a part of the processing performed by the processing apparatus 200 may be performed by the IC chip.

  DESCRIPTION OF SYMBOLS 10 ... Surface observation apparatus (observation apparatus), 100 ... Light source apparatus, 101 ... Light source, 102 ... Collimating lens, 110 ... Polarization conversion apparatus (polarization conversion mechanism), 111 ... Polarizing plate (1st polarization | polarized-light selection member), 112 ... Polarizing plate (second polarization selecting member), 113 ... holding member, 115 ... stepping motor, 120 ... half mirror, 130 ... lens, 150 ... light receiving module, 151 ... polarization filter, 152 ... polarization pattern, 152 '... polarization pattern , 153... Microlens array, 155 Image sensor, 170 Circuit board, 180 Case, 200 Processing unit, 210 Input device, 220 Display device, 230 HDD device, 240 Horizontal drive device, 300 Object.

JP 2008-008787 A

Claims (10)

An observation device for optically observing the surface of an object,
A lens disposed on an optical path of light through the object;
A polarizing filter disposed on an optical path of light passing through the lens;
A microlens array disposed on an optical path of light that has passed through the polarizing filter;
An image sensor having a plurality of light receiving portions disposed on an optical path of light through the microlens array;
An observation apparatus in which an interval between the polarizing filter and the microlens array is equal to or smaller than a lens pitch in the microlens array.   The observation apparatus according to claim 1, wherein an interval between the polarizing filter and the microlens array is equal to or smaller than a size of a light receiving unit in the image sensor.   The observation apparatus according to claim 1, wherein the polarizing filter is formed such that two closest light receiving portions in the image sensor receive linearly polarized light orthogonal to each other.   The observation apparatus according to claim 1, wherein the polarizing filter, the microlens array, and the image sensor are integrated. A light source;
A polarization conversion mechanism that selects any one of two linearly polarized lights orthogonal to each other, converts the light from the light source into the selected linearly polarized light, and emits the light;
A reflection member disposed between the lens and the polarizing filter and configured to reflect a part of linearly polarized light from the polarization conversion mechanism in a direction toward the object through the lens. The observation apparatus according to any one of claims 1 to 4.   The observation apparatus according to claim 5, wherein the reflection member is a half mirror.   The polarization conversion mechanism includes a first polarization selection member that transmits one of the two linearly polarized light, a second polarization selection member that transmits the other, the first polarization selection member, and the second polarization selection. The observation apparatus according to claim 5, further comprising: a driving mechanism that arranges a member that transmits the selected linearly polarized light on an optical path of light from the light source.   The observation device according to claim 1, further comprising: a processing device that determines the presence or absence of at least one of a foreign substance and a defect in the object based on an output signal of the image sensor. .   The observation apparatus according to claim 8, wherein the processing apparatus further obtains a shape of at least one of a foreign substance and a defect in the object. The observation apparatus according to claim 8, wherein the processing apparatus further obtains position information in which at least one of a foreign matter and a defect in the object exists.