WO2013075331A1 - Optical inspection system - Google Patents

Optical inspection system Download PDF

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Publication number
WO2013075331A1
WO2013075331A1 PCT/CN2011/082946 CN2011082946W WO2013075331A1 WO 2013075331 A1 WO2013075331 A1 WO 2013075331A1 CN 2011082946 W CN2011082946 W CN 2011082946W WO 2013075331 A1 WO2013075331 A1 WO 2013075331A1
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WO
WIPO (PCT)
Prior art keywords
image
plane
light
capturing unit
substrate
Prior art date
Application number
PCT/CN2011/082946
Other languages
French (fr)
Inventor
Jean-Philippe Schweitzer
Xiaofeng Lin
Xiaowei Sun
Wenhua Deng
Original Assignee
Saint-Gobain Glass France
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Saint-Gobain Glass France filed Critical Saint-Gobain Glass France
Priority to PCT/CN2011/082946 priority Critical patent/WO2013075331A1/en
Publication of WO2013075331A1 publication Critical patent/WO2013075331A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/8806—Specially adapted optical and illumination features
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/89—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles
    • G01N21/892—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles characterised by the flaw, defect or object feature examined
    • G01N21/896—Optical defects in or on transparent materials, e.g. distortion, surface flaws in conveyed flat sheet or rod
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
    • G01N21/958—Inspecting transparent materials or objects, e.g. windscreens

Definitions

  • the present invention relates to an optical inspection system.
  • the optical inspection system generally includes an imaging system adapted to form an image of the object and a processing unit adapted to detect a defect of the object based on the formed image of the object.
  • the imaging system generally has a normal camera, which includes a normal lens defining a lens plane and an imaging unit such as CCD in which the image is formed.
  • a focus plane, the lens plane and the image plane of the normal camera have to be parallel with each other.
  • the focus plane of the normal camera has a depth of field.
  • the image may be accepted as a well-focused image.
  • the maximum 25 is the depth of field of the focus plane.
  • some objects have complex topography and is not in a plane, and it is possible that these objects can't be positioned within the well-focused area of the normal camerabecause the well-focused area of the normal camera has to be parallel with the lens plane and the image plane of the normal camera.
  • the normal camera will provide poor-focused images for these objects, and it is possible that the optical inspecition system can't detect the defect of the object based on the poor-focused images provided by the normal camera.
  • Embodiments of the present invention provide an optical inspection system, which can provide well-focused images for the object having complex topography and being not in a plane.
  • An imaging system includes: an image capturing unit, wherein a light is irradiated to an inspecting zone of a substrate by a light source and a first part of the light is directly deflected from the inspecting zone to the image capturing unit, and the image capturing unit is adapted to receive the first part of the light for forming a first image in accordance with the received first part of the light, wherein the image capturing unit comprises: a lens defining a lens plane; and an imaging unit defining an image plane on which the first image is formed, wherein the lens plane is substantially unparallel with the image plane.
  • An optical inspection system includes: an image capturing unit, wherein a light is irradiated to an inspecting zone of a substrate by a light source and a first part of the light is directly deflected from the inspecting zone to the image capturing unit, and the image capturing unit is adapted to receive the first part of the light for forming a first image in accordance with the received first part of the light; and a processing unit adapted to detect and categorize a defect located in the inspecting zone of the substrate in accordance with the formed first image, wherein the image capturing unit comprises: a lens defining a lens plane; and an imaging unit defining an image plane on which the first image is formed, wherein the lens plane is substantially unparallel with the image plane.
  • An optical inspection method includes: providing an image capturing unit for receiving a first light directly deflected from an inspecting zone of a substrate, wherein the image capturing unit comprises a lens defining a lens plane and an imaging unit defining an image plane, wherein the lens plane and the image plane are substantially unparallel with each other; forming a first image of the inspecting zone in accordance with the received first light on the image plane, and detecting a defect located in the inspecting zone and categorizing the defect by analyzing the first image.
  • An imaging system includes: an image capturing unit, wherein a light is irradiated to an inspecting zone of a substrate by a light source and a first part of the light is directly deflected from the inspecting zone to the image capturing unit, and wherein the image capturing unit comprises: a lens defining a lens plane; and an imaging unit defining an image plane on which the first image is formed, wherein the lens plane is substantially unparallel with the image plane; and a reflector adapted to reflect a second part of the light deflected from the inspecting zone of the substrate to the image capturing unit, wherein the image capturing unit is adapted to receive the first part of the light and the second part of the light for forming an integrated image on the image plane in accordance with both of the received first part and second part of the light.
  • Fig. 1 is a schematic diagram showing a known optical imaging principle
  • Fig. 2 is a schematic diagram showing an imaging system according to an embodiment of the present invention.
  • Fig. 3 shows a schematic diagram of optical imaging for the imaging system with the normal camera
  • Fig. 4 shows examples of images formed by the imaging system shown in Fig.
  • Fig. 5 shows a schematic diagram of optical imaging for the imaging system with the image capturing unit of the present invention
  • Fig. 6 shows examples of images formed by the imaging system shown in Fig.
  • Fig. 7A illustrates an example of the imaging system having two reflectors
  • Fig. 7B shows a schematic diagram of optical imaging for the imaging system shown in Fig. 7 A;
  • Fig. 7C illustrates another example of the imaging system having two illuminating units.
  • Fig. 8 illustrates an imaging system for forming images of the non-transparent substrate according to an embodiment of the present invention.
  • An embodiment of the present invention provides an optical inspection system for inspecting a defect of a transparent or semi-transparent substrate, which includes an imaging system adapted to form images in accordance with a light from the substrate and a processing unit connected to the imaging system and adapted to detect and categorize a defect of the substrate in accordance with the formed images.
  • Fig. 2 is a schematic diagram showing the imaging system according to an embodiment of the present invention.
  • the imaging system 100 includes an illuminating unit 110, a reflector 120, and an image capturing unit 130.
  • the substrate 160 moves along the direction z at a predefined speed.
  • the illuminating unit 110 is positioned outside a surface Bl of the substrate 160 and adapted to serve as a light source and irradiate a light to an inspecting zone of the substrate 160.
  • the light irradiated to the inspecting zone of the substrate 160 by the illuminating unit 110 may be a non-diffuse light or a diffuse light.
  • the reflector 120 is positioned outside another opposite surface B2 of the substrate 160 and adapted to reflect a second part of the light deflected from the inspecting zone of the substrate 160 (i.e., the second part of the light irradiated to the inspecting zone of the substrate 160 by the illuminating unit 110 and transmitted through the substrate 160 into the reflector 120).
  • the image capturing unit 130 is positioned outside another opposite surface B2 of the substrate 160.
  • the image capturing unit 130 is adapted to receive a first part of the light deflected directly from the inspecting zone of the substrate 160 (i.e., the first part of the light irradiated to the inspecting zone of the substrate 160 by the illuminating unit 110 and transmitted through the substrate 160) to form a first image on the image plane and receive the second part of the light reflected by the reflector 120 to form a second image on the image plane, and the first image and the second image are separated from each other in space.
  • the image capturing unit 130 includes a lens defining a lens plane and an imaging unit defining an image plane on which the first and second images are formed.
  • the lens plane defined by the lens is substantially unparallel with the image plane defined by the imaging unit.
  • the lens plane and the image plane jointly define a focus plane of the image capturing unit 130 and the focus plane has its depth of field for focusing.
  • a tangent extended from the the lens plane and a tangent extended from the image plane meet at a line. In such case, a tangent extended from a focus plane of the capturing unit 130 also passes through the line.
  • the lens plane and the image plane are set such that the inspecting zone of the substrate 160 is positioned substantially within the area defined the depth of field of the focus plane (i.e., the well-focused area), which is formed by extending outwards from each side of the focus plane by half of the depth of field of the focus plane.
  • the depth of field of the focus plane i.e., the well-focused area
  • the first image and the second image formed by the image capturing unit 130 may be processed by the processing unit included in the optical inspection system to detect and categorize a defect of the substrate 160.
  • the processing unit included in the optical inspection system may have the functions of the image constructing module and the image processing module recited in PCT application PCT/CN2010/070791, thus the processing unit included in the optical inspection system may form the first image and the second images, and then process the first and second images to detect and categorize a defect of the substrate 160. All contents recited in PCT application PCT/CN2010/070791 are incoporated herein by reference.
  • Fig. 3 shows a schematic diagram of optical imaging for the imaging system with the normal lens.
  • the imaging system 100 when the imaging system 100 is equipped with a normal camera having the normal lens, the image plane, the lens plane and the focus plane of the normal camera have to be in parallel with each other and thus the well-focused area of the normal camera is also parallel with the image plane of the normal camera.
  • the whole object includes the actual substrate part and the substrate image part in the reflector 120.
  • the actual substrate part is parallel with the image plane of the normal camera and can be positioned within the well-focused area of the normal camera, so the normal camera can have a well-focused image for the actual substrate part as illustrated in the bottom image of Fig.4.
  • the substrate image part in the reflector 120 is not parallel with the image plane of the normal camera and can't be positioned within the well-focused area of the normal camera, so the normal camera can have a poor-focused image for the substrate image part in the reflector 120 as illustrated in the top image of Fig.4.
  • Fig. 5 shows a schematic diagram of optical imaging for the imaging system with the features of the present invention.
  • the imaging system 100 is equipped with the image capturing unit 130.
  • the lens of the image capturing unit 130 is unparallel with the image unit of the image capturing unit 130, so the lens plane defined by the lens of the image capturing unit 130 is unparallel with the image plane defined by the image unit of the image capturing unit 130.
  • the well-focused area of the image capturing unit 130 is not in parallel with the image plane and the lens plane of the image capturing unit 130.
  • the lens and the image unit of the image capturing unit 130 are set such that the actual substrate part and the substrate image part in the reflector 120 are positioned substantially within the well-focused area (the hatched part) of the image capturing unit 130 and thus the image capturing unit 130 can have well-focused images for the actual substrate part and and the substrate image part in the reflector 120, as illustrated in Fig.6.
  • the well-focused area of the image capturing unit 130 is the hatched part shown in Fig. 6.
  • the imaging system 100 includes the reflector 120, but the present invention is not so limited. In other embodiments of the present invention, the imaging system 100 may not include any reflector.
  • the imaging system 100 includes only one reflector or one illuminating unit, but the present invention is not so limited. In other embodiments of the present invention, the imaging system 100 may also include two reflectors or two illuminating units.
  • Fig. 7 A illustrates an example of the imaging system having two reflectors.
  • another reflector 140 is positioned outside the surface B2 of the substrate 160 similar to the reflector 120 and adapted to reflect one part of the light deflected from the substrate 160.
  • Fig. 7B shows a schematic diagram of optical imaging for the imaging system shown in Fig. 7A.
  • the actual substrate part, the substrate image part in the reflector 120 and the substrate image part in the reflector 140 are positioned substantially within the well-focused area of the image capturing unit 130, and the image capturing unit 130 can have well-focused images for the actual substrate part, the substrate image part in the reflector 120 and the substrate image part in the reflector 140.
  • the well-focused area of the image capturing unit 130 is the hatched part shown in Fig. 7B.
  • FIG. 7C illustrates another example of the imaging system having two illuminating units.
  • another illuminating unit 150 is positioned outside the surface B2 of the substrate 160 and adapted to irradiate a light to the substrate 160.
  • the illuminating unit 110 and the illuminating unit 150 irradiate a light to the substrate 160 alternately.
  • the substrate 160 is transparent or semi-transparent, but the substrate is also non-transparent.
  • Fig. 8 illustrates an imaging system for forming images of the non-transparent substrate according to an embodiment of the present invention.
  • the illuminating unit 110 and 170 are positioned outside the surface B2 of the non-transparent substrate 160 and adapted to irradiate a light to the substrate 160 at different angles.
  • the reflector 120 is positioned outside the surface B2 of the non-transparent substrate 160 and adapted to reflect to the image capturing unit 130 a light that is produced by the substrate 160 through reflecting the light irradiated by the illuminating unit 110.
  • the image capturing unit 130 is positioned outside the surface B2 of the substrate 160 and adapted to receive the light that is produced by the substrate 160 throught reflecting the light irradiated by the illuminating unit 170 to form a first image and receive the light reflected by the reflector 120 to form a second image, and the first image and the second image are separated from each other in space.
  • the first image and the second image formed by the image capturing unit 130 are separated from each other in space, but the present invention is not so limited.
  • the image capturing unit 130 may receive the first part of the light and the second part of the light to form an integrated image on the image plane of the image capturing unit 130 in accordance with both of the received first part and second part of the light.
  • a real device or unit as illustrated herein i.e., the illuminating unit
  • the illuminating unit is preferred to be employed as a part of the inspecting system, serving as a controllable light source
  • natural light source such as sunlight or ambient light source can also be relied upon as a light source to provide illuminating function.

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Abstract

An optical inspection system comprises an image capturing unit (130), wherein a light is irradiated to an inspecting zone of a substrate (160) by a light source (110) and a first part of the light is directly deflected from the inspecting zone to the image capturing unit (130), and the image capturing unit (130) is adapt to receive the first part of the light for forming a first image in accordance with the received first part of the light; and a processing unit adapted to detect and categorize a defect located in the inspecting zone of the substrate in accordance with the formed first image, wherein the image capturing unit comprises: a lens defining a lens plane; and an imaging unit defining an image plane on which the first image is formed, wherein the lens plane is substantially unparallel with the image plane. The optical inspection system can take well-focused images for the object having complex topography and being not in a plane.

Description

OPTICAL INSPECTION SYSTEM
Technical Field
The present invention relates to an optical inspection system.
Background Art
An optical inspection system for inspecting a defect of an object such as glass has been proposed. The optical inspection system generally includes an imaging system adapted to form an image of the object and a processing unit adapted to detect a defect of the object based on the formed image of the object.
The imaging system generally has a normal camera, which includes a normal lens defining a lens plane and an imaging unit such as CCD in which the image is formed. A focus plane, the lens plane and the image plane of the normal camera have to be parallel with each other.
The focus plane of the normal camera has a depth of field. As shown in Fig. 1 , the famous imaging equation is expressed as 1/u + 1/v =l/f, wherein u is an object distance, v is an image distance and f is a focal length. Thus, if an object is parallel with the image plane of the normal camera and is located in the focus plane of the normal camera, the normal camera can have a well-focused image for the object. If the object moves and departs from the focus plane of the normal camera, which means that the object distance of the object is u+δ or u-δ now, the image taked by the normal camera will be out of focused. But, if δ is small and the defocusing is very limited so that optical detector (e.g., human eyes or CCD pixel for digital camera) can not be aware of it, the image may be accepted as a well-focused image. The maximum 25 is the depth of field of the focus plane.
An area defined by the depth of field, which is formed by extending outwards from each side of the focus plane of the normal camera by half of the depth of field of the normal camera, is called a well-focused area of the normal camera. If the object is positioned within the well-focused area of the normal camera and is covered by the well-focused area of the normal camera, the normal camera can have a well-focused image for the object. If the object can't be positioned within the well-focused area of the normal camera, the normal camera can have a poor-focused image for the object. Since the focus plane of the normal camera is parallel with the lens plane and the image plane of the normal camera, the well-focused area of the normal camera is also parallel with the lens plane and the image plane of the normal camera.
However, some objects have complex topography and is not in a plane, and it is possible that these objects can't be positioned within the well-focused area of the normal camerabecause the well-focused area of the normal camera has to be parallel with the lens plane and the image plane of the normal camera. In this case, the normal camera will provide poor-focused images for these objects, and it is possible that the optical inspecition system can't detect the defect of the object based on the poor-focused images provided by the normal camera.
Summary
Embodiments of the present invention provide an optical inspection system, which can provide well-focused images for the object having complex topography and being not in a plane.
An imaging system according to embodiments of the present invention includes: an image capturing unit, wherein a light is irradiated to an inspecting zone of a substrate by a light source and a first part of the light is directly deflected from the inspecting zone to the image capturing unit, and the image capturing unit is adapted to receive the first part of the light for forming a first image in accordance with the received first part of the light, wherein the image capturing unit comprises: a lens defining a lens plane; and an imaging unit defining an image plane on which the first image is formed, wherein the lens plane is substantially unparallel with the image plane.
An optical inspection system according to embodiments of the present invention includes: an image capturing unit, wherein a light is irradiated to an inspecting zone of a substrate by a light source and a first part of the light is directly deflected from the inspecting zone to the image capturing unit, and the image capturing unit is adapted to receive the first part of the light for forming a first image in accordance with the received first part of the light; and a processing unit adapted to detect and categorize a defect located in the inspecting zone of the substrate in accordance with the formed first image, wherein the image capturing unit comprises: a lens defining a lens plane; and an imaging unit defining an image plane on which the first image is formed, wherein the lens plane is substantially unparallel with the image plane.
An optical inspection method according to embodiments of the present invention includes: providing an image capturing unit for receiving a first light directly deflected from an inspecting zone of a substrate, wherein the image capturing unit comprises a lens defining a lens plane and an imaging unit defining an image plane, wherein the lens plane and the image plane are substantially unparallel with each other; forming a first image of the inspecting zone in accordance with the received first light on the image plane, and detecting a defect located in the inspecting zone and categorizing the defect by analyzing the first image.
An imaging system according to embodiments of the present invention includes: an image capturing unit, wherein a light is irradiated to an inspecting zone of a substrate by a light source and a first part of the light is directly deflected from the inspecting zone to the image capturing unit, and wherein the image capturing unit comprises: a lens defining a lens plane; and an imaging unit defining an image plane on which the first image is formed, wherein the lens plane is substantially unparallel with the image plane; and a reflector adapted to reflect a second part of the light deflected from the inspecting zone of the substrate to the image capturing unit, wherein the image capturing unit is adapted to receive the first part of the light and the second part of the light for forming an integrated image on the image plane in accordance with both of the received first part and second part of the light.
Brief Description of Drawings These and other features, characteristics and advantages of the present invention will become more apparent by combination of detailed description in conjunction with the drawings. Wherein:
Fig. 1 is a schematic diagram showing a known optical imaging principle;
Fig. 2 is a schematic diagram showing an imaging system according to an embodiment of the present invention;
Fig. 3 shows a schematic diagram of optical imaging for the imaging system with the normal camera;
Fig. 4 shows examples of images formed by the imaging system shown in Fig.
3;
Fig. 5 shows a schematic diagram of optical imaging for the imaging system with the image capturing unit of the present invention;
Fig. 6 shows examples of images formed by the imaging system shown in Fig.
3;
Fig. 7A illustrates an example of the imaging system having two reflectors;
Fig. 7B shows a schematic diagram of optical imaging for the imaging system shown in Fig. 7 A;
Fig. 7C illustrates another example of the imaging system having two illuminating units; and
Fig. 8 illustrates an imaging system for forming images of the non-transparent substrate according to an embodiment of the present invention.
Modes for Carrying Out the Invention
Below, embodiments of the present invention will be explained in conjunction with the figures.
An embodiment of the present invention provides an optical inspection system for inspecting a defect of a transparent or semi-transparent substrate, which includes an imaging system adapted to form images in accordance with a light from the substrate and a processing unit connected to the imaging system and adapted to detect and categorize a defect of the substrate in accordance with the formed images.
Fig. 2 is a schematic diagram showing the imaging system according to an embodiment of the present invention. As shown in Fig. 2, the imaging system 100 includes an illuminating unit 110, a reflector 120, and an image capturing unit 130. As shown in Fig. 2, when a transparent or semi-transparent substrate 160 is inspected, the substrate 160 moves along the direction z at a predefined speed.
The illuminating unit 110 is positioned outside a surface Bl of the substrate 160 and adapted to serve as a light source and irradiate a light to an inspecting zone of the substrate 160. The light irradiated to the inspecting zone of the substrate 160 by the illuminating unit 110 may be a non-diffuse light or a diffuse light.
The reflector 120 is positioned outside another opposite surface B2 of the substrate 160 and adapted to reflect a second part of the light deflected from the inspecting zone of the substrate 160 (i.e., the second part of the light irradiated to the inspecting zone of the substrate 160 by the illuminating unit 110 and transmitted through the substrate 160 into the reflector 120).
The image capturing unit 130 is positioned outside another opposite surface B2 of the substrate 160. The image capturing unit 130 is adapted to receive a first part of the light deflected directly from the inspecting zone of the substrate 160 (i.e., the first part of the light irradiated to the inspecting zone of the substrate 160 by the illuminating unit 110 and transmitted through the substrate 160) to form a first image on the image plane and receive the second part of the light reflected by the reflector 120 to form a second image on the image plane, and the first image and the second image are separated from each other in space.
The image capturing unit 130 includes a lens defining a lens plane and an imaging unit defining an image plane on which the first and second images are formed. The lens plane defined by the lens is substantially unparallel with the image plane defined by the imaging unit. The lens plane and the image plane jointly define a focus plane of the image capturing unit 130 and the focus plane has its depth of field for focusing. A tangent extended from the the lens plane and a tangent extended from the image plane meet at a line. In such case, a tangent extended from a focus plane of the capturing unit 130 also passes through the line. The lens plane and the image plane are set such that the inspecting zone of the substrate 160 is positioned substantially within the area defined the depth of field of the focus plane (i.e., the well-focused area), which is formed by extending outwards from each side of the focus plane by half of the depth of field of the focus plane.
The first image and the second image formed by the image capturing unit 130 may be processed by the processing unit included in the optical inspection system to detect and categorize a defect of the substrate 160. For example, the processing unit included in the optical inspection system may have the functions of the image constructing module and the image processing module recited in PCT application PCT/CN2010/070791, thus the processing unit included in the optical inspection system may form the first image and the second images, and then process the first and second images to detect and categorize a defect of the substrate 160. All contents recited in PCT application PCT/CN2010/070791 are incoporated herein by reference.
Fig. 3 shows a schematic diagram of optical imaging for the imaging system with the normal lens. As shown in Fig. 3, when the imaging system 100 is equipped with a normal camera having the normal lens, the image plane, the lens plane and the focus plane of the normal camera have to be in parallel with each other and thus the well-focused area of the normal camera is also parallel with the image plane of the normal camera. As shown in Fig. 3, for the normal camera, the whole object includes the actual substrate part and the substrate image part in the reflector 120. The actual substrate part is parallel with the image plane of the normal camera and can be positioned within the well-focused area of the normal camera, so the normal camera can have a well-focused image for the actual substrate part as illustrated in the bottom image of Fig.4. Whereas, the substrate image part in the reflector 120 is not parallel with the image plane of the normal camera and can't be positioned within the well-focused area of the normal camera, so the normal camera can have a poor-focused image for the substrate image part in the reflector 120 as illustrated in the top image of Fig.4.
Fig. 5 shows a schematic diagram of optical imaging for the imaging system with the features of the present invention. As shown in Fig. 5, the imaging system 100 is equipped with the image capturing unit 130. The lens of the image capturing unit 130 is unparallel with the image unit of the image capturing unit 130, so the lens plane defined by the lens of the image capturing unit 130 is unparallel with the image plane defined by the image unit of the image capturing unit 130. In such case, the well-focused area of the image capturing unit 130 is not in parallel with the image plane and the lens plane of the image capturing unit 130. As shown in Fig. 5, the lens and the image unit of the image capturing unit 130 are set such that the actual substrate part and the substrate image part in the reflector 120 are positioned substantially within the well-focused area (the hatched part) of the image capturing unit 130 and thus the image capturing unit 130 can have well-focused images for the actual substrate part and and the substrate image part in the reflector 120, as illustrated in Fig.6. The well-focused area of the image capturing unit 130 is the hatched part shown in Fig. 6.
Other Embodiments
Those skilled in the art will understand that in the above embodiment, the imaging system 100 includes the reflector 120, but the present invention is not so limited. In other embodiments of the present invention, the imaging system 100 may not include any reflector.
Those skilled in the art will understand that in the above embodiment, the imaging system 100 includes only one reflector or one illuminating unit, but the present invention is not so limited. In other embodiments of the present invention, the imaging system 100 may also include two reflectors or two illuminating units.
Fig. 7 A illustrates an example of the imaging system having two reflectors. As shown in Fig. 7A, another reflector 140 is positioned outside the surface B2 of the substrate 160 similar to the reflector 120 and adapted to reflect one part of the light deflected from the substrate 160. Fig. 7B shows a schematic diagram of optical imaging for the imaging system shown in Fig. 7A. As shown in Fig. 7B, the actual substrate part, the substrate image part in the reflector 120 and the substrate image part in the reflector 140 are positioned substantially within the well-focused area of the image capturing unit 130, and the image capturing unit 130 can have well-focused images for the actual substrate part, the substrate image part in the reflector 120 and the substrate image part in the reflector 140. The well-focused area of the image capturing unit 130 is the hatched part shown in Fig. 7B.
Further, Fig. 7C illustrates another example of the imaging system having two illuminating units. In the imaging system shown in Fig. 7C, another illuminating unit 150 is positioned outside the surface B2 of the substrate 160 and adapted to irradiate a light to the substrate 160. The illuminating unit 110 and the illuminating unit 150 irradiate a light to the substrate 160 alternately.
Further, those skilled in the art will understand that in the above embodiments, the substrate 160 is transparent or semi-transparent, but the substrate is also non-transparent.
Fig. 8 illustrates an imaging system for forming images of the non-transparent substrate according to an embodiment of the present invention. As shown in Fig. 8, the illuminating unit 110 and 170 are positioned outside the surface B2 of the non-transparent substrate 160 and adapted to irradiate a light to the substrate 160 at different angles. The reflector 120 is positioned outside the surface B2 of the non-transparent substrate 160 and adapted to reflect to the image capturing unit 130 a light that is produced by the substrate 160 through reflecting the light irradiated by the illuminating unit 110. The image capturing unit 130 is positioned outside the surface B2 of the substrate 160 and adapted to receive the light that is produced by the substrate 160 throught reflecting the light irradiated by the illuminating unit 170 to form a first image and receive the light reflected by the reflector 120 to form a second image, and the first image and the second image are separated from each other in space.
Further, those skilled in the art will understand that in the above embodiments, the first image and the second image formed by the image capturing unit 130 are separated from each other in space, but the present invention is not so limited. In other embodiments of the present invention, the image capturing unit 130 may receive the first part of the light and the second part of the light to form an integrated image on the image plane of the image capturing unit 130 in accordance with both of the received first part and second part of the light.
Further, those skilled in the art will understand that although in the above embodiments, a real device or unit as illustrated herein, i.e., the illuminating unit, is preferred to be employed as a part of the inspecting system, serving as a controllable light source, it should be also noted that natural light source such as sunlight or ambient light source can also be relied upon as a light source to provide illuminating function.
Those skilled in the art will understand that various amendments and modifications on the embodiments of the present invention may be made without being depart from spirits of the invention and the amendments and modifications should fall into the protection scope of the invention. Therefore, the protection scope of the invention will be defined by the claims appended.

Claims

1. An imaging system, comprising:
an image capturing unit, wherein a light is irradiated to an inspecting zone of a substrate by a light source and a first part of the light is directly deflected from the inspecting zone to the image capturing unit, and the image capturing unit is adapted to receive the first part of the light for forming a first image in accordance with the received first part of the light,
wherein the image capturing unit comprises:
a lens defining a lens plane; and
an imaging unit defining an image plane on which the first image is formed, wherein the lens plane is substantially unparallel with the image plane.
2. The imaging system of claim 1, further comprising an illuminating unit serving as the light source.
3. The imaging system of claim 1 or 2, wherein the lens plane and the image plane jointly define a focus plane characterized with a depth of field for focusing, and a tangent extended from the the lens plane and a tangent extended from the image plane meet at a line,
wherein the inspecting zone of the substrate is positioned substantially within an area defined by the depth of field.
4. The imaging system of claim 1, 2 or 3 further comprising:
a reflector adapted to reflect a second part of the light deflected from the inspecting zone of the substrate to the image capturing unit,
wherein the image capturing unit is further adapted to receive the reflected second part of the light for forming a second image on the image plane in accordance with the received second part of the light reflected from the reflector.
5. An optical inspection system, comprising: an image capturing unit, wherein a light is irradiated to an inspecting zone of a substrate by a light source and a first part of the light is directly deflected from the inspecting zone to the image capturing unit, and the image capturing unit is adapted to receive the first part of the light for forming a first image in accordance with the received first part of the light; and
a processing unit adapted to detect and categorize a defect located in the inspecting zone of the substrate in accordance with the formed first image,
wherein the image capturing unit comprises:
a lens defining a lens plane; and
an imaging unit defining an image plane on which the first image is formed, wherein the lens plane is substantially unparallel with the image plane.
6. The optical inspection system of claim 5, further comprising an illuminating unit serving as the light source.
7. The optical inspection system of claim 5 or 6, wherein the lens plane and the image plane jointly define a focus plane characterized with a depth of field for focusing, and a tangent extended from the the lens plane and a tangent extended from the image plane meet at a line,
wherein the inspecting zone of the substrate is positioned substantially within an area defined by the depth of field.
8. The optical inspection system of claim 5, 6 or 7, further comprising:
a reflector adapted to reflect a second part of the light deflected from the inspecting zone of the substrate to the image capturing unit,
wherein the image capturing unit is further adapted to receive the reflected second part of the light for forming a second image on the image plane in accordance with the received second part of the light reflected from the reflector, and
the processing unit is further adapted to obtain 3 -dimensional information of the defect located in the inspecting zone of the substrate in accordance w image and the second image.
9. An optical inspection method, comprising:
providing an image capturing unit for receiving a first light directly deflected from an inspecting zone of a substrate, wherein the image capturing unit comprises a lens defining a lens plane and an imaging unit defining an image plane, wherein the lens plane and the image plane are substantially unparallel with each other; forming a first image of the inspecting zone in accordance with the received first light on the image plane, and
detecting a defect located in the inspecting zone and categorizing the defect by analyzing the first image.
10. The optical inspection method of claim 9, wherein the lens plane and the image plane jointly define a focus plane characterized with a depth of field for focusing, and a tangent extended from the the lens plane and a tangent extended from the image plane meet at a line,
wherein the inspecting zone of the substrate is positioned substantially within an area defined by the depth of field.
11. The optical inspection method of claim 9, further comprising:
providing a reflector for reflecting a second light deflected from the inspecting zone of the substrate to the image capturing unit;
forming a second image of the inspecting zone on the image plane in accordance with the second light received by the image capturing unit from the reflector; and
obtaining 3-dimensional information of the defect of the substrate by analyzing the second image in addition to the first image.
12. A substrate inspected by the optical inspection system of claim 5, 6, 7 or 8 or by the optical inspection method of claim 9, 10 or 11.
13. An imaging system, comprising:
an image capturing unit, wherein a light is irradiated to an inspecting zone of a substrate by a light source and a first part of the light is directly deflected from the inspecting zone to the image capturing unit, and
wherein the image capturing unit comprises:
a lens defining a lens plane; and
an imaging unit defining an image plane on which the first image is formed, wherein the lens plane is substantially unparallel with the image plane; and a reflector adapted to reflect a second part of the light deflected from the inspecting zone of the substrate to the image capturing unit,
wherein the image capturing unit is adapted to receive the first part of the light and the second part of the light for forming an integrated image on the image plane in accordance with both of the received first part and second part of the light.
14. The imaging system of claim 13, further comprising an illuminating unit serving as the light source.
PCT/CN2011/082946 2011-11-25 2011-11-25 Optical inspection system WO2013075331A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1993980A (en) * 2004-08-04 2007-07-04 菲卡姆数字发展有限及两合公司 Optical image converter system
CN101460878A (en) * 2006-06-05 2009-06-17 诺基亚公司 Method and device for position sensing of an optical component in an imaging system
CN102081047A (en) * 2009-11-27 2011-06-01 法国圣-戈班玻璃公司 Method and system for distinguishing defects of substrate
JP2011145160A (en) * 2010-01-14 2011-07-28 Technos Kk Device and method for multi-focus inspection

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1993980A (en) * 2004-08-04 2007-07-04 菲卡姆数字发展有限及两合公司 Optical image converter system
CN101460878A (en) * 2006-06-05 2009-06-17 诺基亚公司 Method and device for position sensing of an optical component in an imaging system
CN102081047A (en) * 2009-11-27 2011-06-01 法国圣-戈班玻璃公司 Method and system for distinguishing defects of substrate
JP2011145160A (en) * 2010-01-14 2011-07-28 Technos Kk Device and method for multi-focus inspection

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