HIGH SPEED OPTICAL INSPECTION SYSTEM WITH CAMERA ARRAY AND COMPACT, INTEGRATED ILLUMINATOR

• US 20110069878A1
• Filed: 09/21/2010
• Published: 03/24/2011
• Est. Priority Date: 09/22/2009
• Status: Active Grant

• Current Assignee: CyberOptics Corporation (Nordson Corporation)
• Original Assignee: CyberOptics Corporation (Nordson Corporation)
• Inventors: Haugan, Carl E., Kranz, David M., Caruso, Beverly, Rose, Steven A., Case, Steven K.
• Granted Patent: US 8,670,031 B2
• Time in Patent Office: Days
• US Class Current: 382/152
• CPC Class Codes: G01N 21/8806 Specially adapted optical and illumination features
• CPC Class Codes: G01N 21/8903 using a multiple detector array
• CPC Class Codes: G01N 21/956 Inspecting patterns on the surface of objects contactless testing of electronic circuits G01R31/308; testing currency G07D; manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: G06V 10/141 Control of illumination
• CPC Class Codes: G06V 10/145 Illumination specially adapted for pattern recognition, e.g. using gratings
• CPC Class Codes: G06V 10/147 Details of sensors, e.g. sensor lenses fingerprint or palmprint sensors G06V40/13; vascular sensors G06V40/145; eye sensors G06V40/19

Abstract

An optical inspection system is provided for inspecting a workpiece including a feature to be inspected. The system includes a workpiece transport configured to transport the workpiece in a nonstop manner. An illuminator is configured to provide a first strobed illumination field type and a second strobed illumination field type. The illuminator includes a light pipe having a first end proximate the feature, and a second end opposite the first end and spaced from the first end. The light pipe also has at least one reflective sidewall. The first end has an exit aperture and the second end has at least one second end aperture to provide a view of the feature therethrough. An array of cameras is configured to digitally image the feature. The array of cameras is configured to generate a first plurality of images of the feature with the first illumination field and a second plurality of images of the feature with the second illumination field. A processing device is operably coupled to the illuminator and the array of cameras, the processing device is configured to store at least some of the first and second plurality of images and provide the first and second pluralities to an other device.

Claims

1. An optical inspection system for inspecting a workpiece including a feature to be inspected, the system comprising:

a workpiece transport configured to transport the workpiece in a nonstop manner; and

an illuminator configured to provide a first strobed illumination field type and a second strobed illumination field type, the illuminator including a light pipe having a first end proximate the feature, and a second end opposite the first end and spaced from the first end, the light pipe also having at least one reflective sidewall, and wherein the first end has an exit aperture and the second end has at least one second end aperture to provide a view of the feature therethrough;

an array of cameras configured to digitally image the feature, wherein the array of cameras is configured to generate a first plurality of images of the feature with the first illumination field and a second plurality of images of the feature with the second illumination field; and

a processing device operably coupled to the illuminator and the array of cameras, the processing device being configured to store at least some of the first and second plurality of images and provide the first and second pluralities to an other device.

2. The optical inspection system of claim 1, wherein a first plurality of cameras of the array of cameras includes non-telecentric optics and wherein the cameras of the first plurality of cameras are aligned with one another along an axis perpendicular to a direction of workpiece motion.

3. The optical inspection system of claim 2, wherein a second plurality of cameras of the array of cameras includes non-telecentric optics and wherein the cameras of the second plurality of cameras are aligned with one another along an axis perpendicular to the direction of workpiece motion, but spaced from the first plurality of cameras in a direction of the workpiece motion.

4. The optical inspection system of claim 1, wherein the array of cameras includes:

a first plurality of cameras having telecentric optics, wherein the cameras of the first plurality of cameras are aligned with one another along an axis perpendicular to a direction of workpiece motion, and have fields of view that do not overlap with one another;

a second plurality of cameras having telecentric optics, wherein the cameras of the second plurality of cameras are aligned with one another along an axis perpendicular to a direction of workpiece motion, and have fields of view that do not overlap with one another; and

wherein the first and second pluralities of cameras have fields of view that are staggered in a direction perpendicular to workpiece motion.

5. The optical inspection system of claim 4, wherein the first and second pluralities of cameras are staggered such that each camera in the array has at least a portion of its field of view that is not overlapped by any other camera in the array.

6. The optical inspection system of claim 1, and further comprising an encoder operably coupled to the workpiece transport to provide an indication of workpiece motion to the processing device.

7. The optical inspection system of claim 6, wherein the indication has a resolution of approximately 100 microns.

8. The optical inspection system of claim 1, wherein the illuminator includes at least one arc lamp.

9. The optical inspection system of claim 1, wherein the illuminator includes at least one light emitting diode.

10. The optical inspection system of claim 1, wherein the light pipe includes a plurality of reflective sidewalls.

11. The optical inspection system of claim 1, wherein the at least one reflective sidewall includes a curved reflective surface that preserves illumination elevation angle while mixing illumination azimuthally.

12. The optical inspection system of claim 1, wherein the illuminator includes at least one mirror disposed to reflect at least a portion of illumination to a desired source elevation angle.

13. The optical inspection system of claim 12, wherein the at least one mirror is angled to reflect the portion of illumination toward the at least one reflective sidewall at the desired elevation angle.

14. The optical inspection system of claim 1, wherein the array of cameras is mounted proximate the second end of the light pipe and is configured to view the feature through at least one second end aperture.

15. The optical inspection system of claim 14, wherein the illuminator includes an illumination mixing chamber disposed proximate the second end, and wherein the mixing chamber and the light pipe are separated by a translucent diffuser having at least one diffuser aperture aligned with each respective at least one second end aperture.

16. The optical inspection system of claim 15, wherein a first light source is configured to introduce strobed illumination into the mixing chamber.

17. The optical inspection system of claim 16, wherein a first darkfield light source is configured to introduce strobed illumination into the light pipe between the diffuser and the first end.

18. The optical inspection system of claim 17, and further comprising a second darkfield light source configured to introduce additional illumination into the light pipe between the diffuser and the first end.

19. The optical inspection system of claim 15, wherein the mixing chamber includes a plurality of reflective surfaces.

20. The optical inspection system of claim 1, wherein the processing device includes random access memory configured to store a plurality of images from each camera of the array of cameras.

21. The optical inspection system of claim 20, wherein the random access memory has a capacity that is sufficient to store a number of images to represent the entire workpiece for each of the first and second pluralities of images.

22. The optical inspection system of claim 21, wherein each camera in the array of cameras has a resolution of about 5 megapixels and the random access memory has a capacity of about 2.0 gigabytes.

23. The optical inspection system of claim 21, wherein the processing device includes a high-speed data transfer bus to provide the stored images to the other device.

24. The optical inspection system of claim 23, wherein the processing device is configured to simultaneously acquire and store images from the array of cameras while providing the stored images to the other device.

25. The optical inspection device of claim 23, wherein the high-speed data transfer bus operates in accordance with the peripheral component interconnect express (PCIe) bus.

26. The optical inspection system of claim 23, wherein the other device is configured to provide an inspection result relative to the feature on the workpiece based, at least in part, upon the first and second pluralities of images.

27. A method of inspecting an article of manufacture having at least one region of interest to provide an inspection result, the method comprising:

generating relative motion between the article of manufacture and a camera array;

simultaneously acquiring images from the camera array through a light pipe during the relative motion and while strobing a first illumination field type upon the article of manufacture;

generating a stitched image with the acquired images;

determining an inspection result relative to the at least one region of interest based, at least in part, upon the stitched image; and

providing the inspection result.

28. The method of claim 27, and further comprising:

acquiring additional images from the camera array through the light pipe while strobing a second illumination field type upon the article of manufacture;

generating an additional stitched image from the additional images acquired from the camera array; and

determining the inspection result relative to the at least one region of interest based, at least in part, upon the additional stitched image.

29. The method of claim 27, wherein the first illumination field type is darkfield.

30. The method of claim 29, wherein the second illumination field type is cloudy day.

31. The method of claim 29, wherein the second illumination field type is brightfield.

32. The method of claim 28, wherein the first and second illumination field types are energized alternately.

33. The method of claim 27, wherein the image stitching is used to correct for workpiece positional error.

34. The method of claim 27, wherein the stitching is used to correct for workpiece warpage.

35. The method of claim 27, and further comprising storing all images in random access memory prior to transferring the images to a computer.

36. The method of claim 27, and further comprising providing at least some images to an other device while collecting images from the camera array.