WO2008094339A1 - Machine vision system for inspecting a moving object with a specular reflecting surface - Google Patents

Machine vision system for inspecting a moving object with a specular reflecting surface Download PDF

Info

Publication number
WO2008094339A1
WO2008094339A1 PCT/US2007/085125 US2007085125W WO2008094339A1 WO 2008094339 A1 WO2008094339 A1 WO 2008094339A1 US 2007085125 W US2007085125 W US 2007085125W WO 2008094339 A1 WO2008094339 A1 WO 2008094339A1
Authority
WO
WIPO (PCT)
Prior art keywords
system
camera
moving object
subsystem
lighting subsystem
Prior art date
Application number
PCT/US2007/085125
Other languages
French (fr)
Inventor
Alex Klooster
Douglas Davidson
Jon Upham
Original Assignee
Coherix, Inc.
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
Priority to US82967106P priority Critical
Priority to US60/829,671 priority
Priority to US86640306P priority
Priority to US60/866,403 priority
Priority to US60/948,153 priority
Priority to US94815307P priority
Priority to PCT/US2007/081560 priority patent/WO2008112021A2/en
Priority to USPCT/US2007/81560 priority
Application filed by Coherix, Inc. filed Critical Coherix, Inc.
Publication of WO2008094339A1 publication Critical patent/WO2008094339A1/en

Links

Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using infra-red, visible or ultra-violet light
    • G01N21/84Systems specially adapted for particular applications
    • G01N21/88Investigating the presence of flaws or contamination
    • G01N21/95Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
    • G01N21/956Inspecting patterns on the surface of objects
    • G01N21/95684Patterns showing highly reflecting parts, e.g. metallic elements
    • GPHYSICS
    • G06COMPUTING; CALCULATING; COUNTING
    • G06KRECOGNITION OF DATA; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K9/00Methods or arrangements for reading or recognising printed or written characters or for recognising patterns, e.g. fingerprints
    • G06K9/20Image acquisition
    • G06K9/2027Illumination control

Abstract

As shown in the figures, the preferred embodiment of the invention is a machine vision system for inspecting a moving object with a specular reflecting surface. The machine vision system includes a camera subsystem that captures images of a moving object with a specular reflecting surface when the object moves into a viewing area, a diffusing element, a primary lighting subsystem that indirectly illuminates the moving object, and a controller that controls the camera subsystem and the primary lighting subsystem. The system has been specifically designed for illuminating a moving object, such as the connecting terminals (e.g., leads, ball grids, and pads) of packaged electronic components in a manufacturing facility. The system may, however, be used to illuminate any suitable moving or non-moving object.

Description

MACHINE VISION SYSTEM FOR INSPECTING A MOVING OBJECT WITH A SPECULAR REFLECTING SURFACE

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part of international application number PCT/US2006/023030 filed on 13 JUN 2006 and entitled "Lighting Subsystem for a Machine Vision System", which claims priority to US Provisional Application 60/689,966 filed on 13 JUN 2005.

[0002] This application is also a continuation-in-part of international application number PCT/US07/81560 filed on 16 OCT 2007 and entitled "System for Illuminating and Imaging an Object with a Specular Reflecting Surface", which claims priority to US Provisional Application 60/829,671 filed on 16 OCT 2006. [0003] This application also claims the benefit of both US Provisional

Application number 60/866,403 filed 17 NOV 2006 and US Provisional Application number 60/948,153 filed on 05 JUL 2007. All six patent documents (the two international applications and the four provisional applications) are incorporated in their entirety by this reference.

TECHNICAL FIELD

[0004] This invention relates generally to the machine vision field, and more specifically to new and useful lighting subsystem in the machine vision field.

BACKGROUND [0005] Semiconductor components are composed of several different elements

(body, leads, balls, pads, etc.). Each element can have a complex shape presenting surfaces at different angles to the camera. Each element can be constructed from different materials with different reflectance properties. The reflectance varies from diffuse to specular (mirror like). The 3D inspection of these devices requires very accurate imaging of all surfaces to be measured. The 3D inspection of these objects using any form of triangulation requires a view of the object from different angles. Viewing the object from different angles amplifies lighting problems. The camera subsystem may receive a high contrast image of an object from one view, and almost no contrast in the image of the same object from an alternate view. Thus, there is a need in the machine vision field to create a new and useful machine vision system and method for multi-dimensional metrology and inspection of semiconductor components. This invention provides such a system.

BRIEF DESCRIPTION OF THE FIGURES

[0006] FIGURES 1 and 2 are perspective views of the system of the preferred embodiment.

[0007] FIGURE 3 is a schematic representation of the controller of the first preferred embodiment.

[0008] FIGURE 4 is a detailed cross-section view of a section of the diffusing element and a camera of the camera subsystem of the preferred embodiment. [0009] FIGURE 5 is a perspective view of the second lighting subsystem of a variation of the preferred embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The following description of the preferred embodiments of the invention is not intended to limit the invention to these preferred embodiments, but rather to enable any person skilled in the art to make and use this invention. [0011] As shown in FIGURES 1-3, the preferred embodiment of the invention is a machine vision system 100 for inspecting a moving object with a specular reflecting surface. The machine vision system 100 includes a camera subsystem 110 that captures images of a moving object with a specular reflecting surface when the object moves into a viewing area, a diffusing element 120, a primary lighting subsystem 130 that indirectly illuminates the moving object, and a controller 140 that controls the camera subsystem 110 and the primary lighting subsystem 130. The system 100 has been specifically designed for illuminating a moving object, such as the connecting terminals (e.g., leads, ball grids, and pads) of packaged electronic components in a manufacturing facility. The system 100 may, however, be used to illuminate any suitable moving or non-moving object.

[0012] The camera subsystem 110 of the preferred embodiment functions to capture multiple images of a moving object when the object moves into a viewing area. Preferably, the camera subsystem 110 includes a first camera 112 and a second camera 114 to provide information on the moving object from several angles. More preferably, the camera subsystem 110 also includes a third camera 116. The camera subsystem 110 may, however, include any suitable number of cameras to provide information on the moving object from several angles. Each camera is preferably a CCD-type camera with a resolution of at least 2MB at 12-bit grayscale and a field of view of at least 50 mm by 50 mm. Each camera may, however, be any suitable type of image capturing device with any suitable resolution and any suitable field of view. Each camera preferably has a unique viewing angle of the viewing area. The first camera 112 and the second camera 114 preferably have acute and obtuse viewing angles that are complimentary (e.g., 6o° and 1200), while the third camera 116 preferably has a perpendicular viewing angle (i.e., 900). The cameras may, however, be arranged with any suitable viewing angle.

[0013] The diffusing element 120 of the preferred embodiment functions as a base for a diffusive and reflective surface that reflects the light from the primary lighting subsystem 130 onto the specularly reflective surface of the moving object, and functions to define a first opening and a second opening for the camera subsystem 110 near an apex 128 of the diffusing element 120. The diffusing element 120 is preferably convex shaped to provide substantially uniform illumination, more preferably shaped like a pyramid, a cone, or a hemisphere, but alternatively may be any suitable shape. The diffusive and reflective surface functions to reflect and randomly diffuse light from the primary lighting subsystem 130. For example, if the light sources of the primary lighting subsystem 130 are coherent light sources, the diffusive and reflective surface functions to transform the light from coherent light source into light that is diffused incoherently in all directions. The diffusivity and reflectivity of the surface are preferably both highly efficient. The surface is preferably substantially uniform in the diffusivity, but may alternatively have any diffusivity. While the reflectivity of the surface is preferably high such to improve efficiency, the surface may allow some portion of the light to pass through the surface, perhaps to illuminate other portions of the system, or to provide an ambient light source for another application.

[0014] The first opening and the second opening, which are located near the apex 128 of the diffusing element 120, function to substantially reduce the narcissus effect of the camera subsystem 110. The "narcissus effect" occurs when a camera receives a virtual image of itself and sees a black hole, which is an inaccurate capture of the "true" image of the moving object. As shown in FIGURE 4, with a small enough aperture, the only area where there is no effective object illumination is at a single point perpendicular to the center of the aperture. This single point preferably corresponds to one pixel in the camera, however, it may correspond to a group of pixels in the camera. The first camera 112 is located behind the first opening, while the second camera 114 is located behind the second opening. In one variation, the openings preferably have a diameter that is significantly less than the width and height of the camera. In another variation, the opening acts as an aperture stop for the camera of the camera subsystem 110 and, more preferably, functions as the smallest aperture stop for the camera of the camera subsystem 110. The openings preferably have a circular shape and a particular size. Preferably, the aperture is sized as small as possible to still allow the full resolution and sensitivity of the camera. If the camera subsystem 110 includes more than two cameras, then the diffusing element 120 preferably includes more than two openings near the apex 128 and the extra cameras are located behind the extra openings.

[0015] In the preferred embodiment, as shown in FIGURE 1, the system 100 also includes a mirror assembly. The mirror assembly functions to allow compactness of the system and to facilitate particular viewing angles of the first camera 112 and the second camera 114. Preferably, the mirror assembly includes a first mirror 152 that optically folds the view of the first camera 112, and a second mirror 154 that optically folds the view of the second camera 114. [0016] As shown in FIGURES 1, 2, and 5, the primary lighting subsystem 130 of the preferred embodiment functions to indirectly illuminate the moving object. The primary lighting subsystem 130 includes light sources aimed directly at the diffusing element 120, and aimed only indirectly at the moving object through the diffusing element 120. The primary lighting subsystem 130 preferably includes light banks, which each consist of a group of light sources that are arranged in a plane and are aimed directly at the diffusing element 120. The light sources of the primary lighting subsystem 130 function to provide a high-intensity illumination of the moving object. The primary lighting subsystem 130 preferably includes at least 48 high-intensity LEDs, which are preferably arranged in a six-sided pattern with four sets of 12 high-intensity LEDs.

[0017] The high-intensity LEDs are preferably cyan LEDs (in the 500 nm to

510 nm range), which provide surprisingly greater image contrast. The cyan LED preferably emits cyan light in the 490 nm to 530 nm range, more preferably emits cyan light in the 500 nm to 510 nm range, and most preferably emits cyan light at 505 nm. As used herein, an "LED" or "light emitting diode" refers to a device having a stack of semiconductor layers (a "chip"), including an active region that emits light when biased to produce an electrical current flow through the device. A "cyan LED" is an LED that emits cyan light. In reference to the visible spectrum, cyan light is the color obtained by mixing equal amounts of green and blue light or by removing red light from white light. Cyan light is also called aqua, teal, or blue-green light. The high-intensity LEDs may, however, be any suitable LEDs and may emit any suitable wavelength or wavelengths.

[0018] As shown in FIGURE 3, the controller 140 of the preferred embodiment, which is connected to the primary lighting subsystem 130, functions to control the primary lighting subsystem 130 to allow observation of the moving object under different conditions. In one variation, the controller 140 controls the activation of the primary lighting subsystem 130. Based on the information collected by a machine vision subsystem, the controller 140 may adjust the activation of the light sources of the primary lighting subsystem 130 to strobe at a faster or slower cycle (e.g., 50ms), at an earlier or later time within the cycle (+ lms), for a longer or shorter duration (e.g., 5-50 microseconds), and/or at a higher or lower intensity (e.g., 0-50 amps). The controller 140 may, however, adjust any suitable parameter of the primary lighting subsystem 130 to allow observation of the moving object. [0019] In the preferred embodiment, the system 100 also includes a processor that functions to combine the images from the camera subsystem 110 into a single image. Preferably, the images are combined into a three-dimensional image. In one variation, the image combination has the effect of reducing narcissus effects in the image. The narcissus effect occurs when the camera subsystem 110 receives a virtual image of its own sensor and sees a black hole, usually when a reflective object surface reflects an image of the camera aperture back onto itself. The processor preferably combines at least two images from different perspectives, more preferably with different locations exhibiting the narcissus effect, and preferably provides an image that at least partially corrects for the narcissus effects. As more images from more perspectives are taken, better corrections can be made for the narcissus effect, and better images can be achieved. Preferably, three images captured from three different perspectives are combined to form a corrected image. Further, in the preferred embodiment, the images from multiple perspectives are also combined to generate three-dimensional images of the objects, with reduced narcissus effects, particularly on specularly reflecting surfaces, such as semiconductor wafers. [0020] In a variation of the preferred embodiment, as shown in FIGURES 1, 2, and 5, the system 100 also includes a secondary lighting subsystem 160 to directly illuminate a moving object. The secondary lighting subsystem 160 preferably includes light sources aimed directly toward the viewing area of the camera subsystem 110. In this variation, the controller 140, which is also connected to the secondary lighting subsystem 160, functions to control the primary lighting subsystem 130 and the secondary lighting subsystem 160. The controller 140 selectively activates and/or adjusts the intensity of the primary lighting subsystem 130 and/or the secondary lighting subsystem 160 to produce different incident light illumination angles, while ensuring a substantial degree of illumination symmetry. Through the manipulation of the activation of the camera subsystem 110, the primary lighting subsystem 130, and the secondary lighting subsystem 160, the system 100 of the variation of the preferred embodiment may effectively freeze and inspect the reflectance of the illumination by the moving object. [0021] As a person skilled in the art will recognize from the previous detailed description and from the figures and claims, modifications and changes can be made to the preferred embodiments of the invention without departing from the scope of this invention as defined in the following claims.

Claims

CLAIMS We Claim:
1. A machine vision system for inspecting a moving object with a specular reflecting surface, comprising:
• a diffusing element having a generally concave shape with an apex and defining both a first opening and a second opening near the apex;
• a camera subsystem that captures images of a moving object with a specular reflecting surface, the camera subsystem including a first camera located behind the first opening of the diffusing element and a second camera located behind the second opening of the diffusing element;
• a primary lighting subsystem that indirectly illuminates the moving object, wherein the primary lighting subsystem includes light sources aimed directly at the diffusing element and only indirectly at the moving object via the diffusing element; and
• a controller that controls the camera subsystem and the primary lighting subsystem.
2. The system of claim i wherein the controller selectively strobes the primary lighting subsystem to effectively freeze the moving object when the object moves into a viewing area.
3. The system of claim 1 wherein the controller selectively adjusts the intensity of the light sources of the primary lighting subsystem.
4- The system of claim l further comprising a processor that, based on the images from the camera subsystem, reduces the narcissus effects caused by the specular reflecting surface of the moving object.
5. The system of claim 4, wherein the processor combines the images into a three-dimensional image.
6. The system of claim 1 wherein the diffusing element includes a diffusive and reflective surface that provides substantially uniform diffusivity and substantially uniform reflectance of light from the light sources of the primary lighting subsystem.
7. The system of claim 1 wherein the first opening acts as an aperture stop for the first camera, and wherein the second opening acts as an aperture stop for the second camera.
8. The system of claim 7 wherein the first opening acts as the smallest aperture stop for the first camera, and wherein the second opening acts as the smallest aperture stop for the second camera.
9. The system of claim 1 wherein the diffusing element further defines a third opening, and wherein the camera subsystem further includes a third camera located behind the third opening.
10. The system of claim 9 wherein the third opening acts as an aperture stop for the third camera.
11. The system of claim 10 wherein the third opening acts as the smallest aperture stop for the third camera.
12. The system of claim i wherein light sources of the primary lighting subsystem are light emitting diodes.
13. The system of claim 12 wherein the light emitting diodes are adapted to emit Cyan light.
14. The system of claim 12 wherein the light emitting diodes are adapted to emit light having a wavelength in the range from 490 nm to 530 nm.
15. The system of claim 14 wherein the light emitting diodes are adapted to emit light having a wavelength in the range from 500 nm to 510 nm.
16. The system of claim 15 wherein the light emitting diodes are adapted to emit light having a wavelength of about 505 nm.
17. The system of claim 1 further comprising a secondary lighting subsystem that directly illuminates the moving object, wherein the secondary lighting subsystem includes light sources aimed directly at the moving object.
18. The system of claim 17 wherein the controller selectively activates one or more of the primary lighting subsystem and the secondary lighting subsystem. 19- The system of claim 18 wherein the controller selectively adjusts the intensity of the light sources of the primary lighting subsystem and the light sources of the secondary lighting subsystem.
PCT/US2007/085125 2006-10-16 2007-11-19 Machine vision system for inspecting a moving object with a specular reflecting surface WO2008094339A1 (en)

Priority Applications (8)

Application Number Priority Date Filing Date Title
US82967106P true 2006-10-16 2006-10-16
US60/829,671 2006-10-16
US86640306P true 2006-11-17 2006-11-17
US60/866,403 2006-11-17
US94815307P true 2007-07-05 2007-07-05
US60/948,153 2007-07-05
PCT/US2007/081560 WO2008112021A2 (en) 2006-10-16 2007-10-16 System for illuminating and imaging an object with a specular reflecting surface
USPCT/US2007/81560 2007-10-16

Publications (1)

Publication Number Publication Date
WO2008094339A1 true WO2008094339A1 (en) 2008-08-07

Family

ID=39674372

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2007/085125 WO2008094339A1 (en) 2006-10-16 2007-11-19 Machine vision system for inspecting a moving object with a specular reflecting surface

Country Status (1)

Country Link
WO (1) WO2008094339A1 (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5201576A (en) * 1992-04-30 1993-04-13 Simco/Ramic Corporation Shadowless spherical illumination system for use in an article inspection system
US6603103B1 (en) * 1998-07-08 2003-08-05 Ppt Vision, Inc. Circuit for machine-vision system
US7144121B2 (en) * 2003-11-14 2006-12-05 Light Prescriptions Innovators, Llc Dichroic beam combiner utilizing blue LED with green phosphor
US20070221847A1 (en) * 2004-01-22 2007-09-27 Farran Technology Limited Illumination Method and Apparatus

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5201576A (en) * 1992-04-30 1993-04-13 Simco/Ramic Corporation Shadowless spherical illumination system for use in an article inspection system
US6603103B1 (en) * 1998-07-08 2003-08-05 Ppt Vision, Inc. Circuit for machine-vision system
US7144121B2 (en) * 2003-11-14 2006-12-05 Light Prescriptions Innovators, Llc Dichroic beam combiner utilizing blue LED with green phosphor
US20070221847A1 (en) * 2004-01-22 2007-09-27 Farran Technology Limited Illumination Method and Apparatus

Similar Documents

Publication Publication Date Title
TWI513273B (en) Scanning projectors and image capture modules for 3d mapping
TWI302756B (en) Imaging semiconductor structures using solid state illumination
US5365084A (en) Video inspection system employing multiple spectrum LED illumination
JP4625837B2 (en) Flashlight that forms a uniform image
US8878929B2 (en) Three dimensional shape measurement apparatus and method
US9736459B2 (en) Generation of patterned radiation
US6556858B1 (en) Diffuse infrared light imaging system
JP6045676B2 (en) Intraoral imaging device
DE112004000329B4 (en) Coaxial small angle dark field illumination device
CN101573988B (en) Using a plurality of cameras reduce specular reflection
US8493558B2 (en) Surface inspection apparatus
US6075883A (en) Method and system for imaging an object or pattern
CN100533252C (en) Image capturing apparatus
US6385507B1 (en) Illumination module
KR100880418B1 (en) Automated optical inspection system
US7276719B2 (en) Device for a goniometric examination of the optical properties of surfaces
US20060033922A1 (en) Device for a goniometric examination of optical properties of surfaces
CN1914492B (en) Method and system for wavelength-dependent imaging and detection using a hybrid filter
EP2381215A1 (en) Shape measurement apparatus and calibration method
KR20130058665A (en) Systems and methods for spatially controlled scene illumination
DE10244444A1 (en) Control lighting device
JP6129983B2 (en) Artificial lighting device
JP3354131B2 (en) Article surface inspection lighting
US10466359B2 (en) Method and system for light patterning and imaging
TW201100779A (en) System and method for inspecting a wafer (3)

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 07871529

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase in:

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 07871529

Country of ref document: EP

Kind code of ref document: A1