Light array system and method for illumination of objects imaged by imaging systems

• US 6,286,978 B1
• Filed: 07/18/2000
• Issued: 09/11/2001
• Est. Priority Date: 08/24/1998
• Status: Expired due to Fees

• Current Assignee: Intelligent Reasoning Systems, Inc. (KLA Corporation)
• Original Assignee: Intelligent Reasoning Systems, Inc. (KLA Corporation)
• Inventors: Lewin, Alvaro D., DeYong, Mark R., Tait, Robert W.
• Primary Examiner(s): Husar, Stephen
• Assistant Examiner(s): WARD, JOHN A
• Application Number:
  US09/618,906
• Time in Patent Office: 420 Days
• Field of Search: 362/249, 362/282, 362/252, 362/283, 362/800, 362/347, 362/350, 362/235
• US Class Current: 362/249.06
• CPC Class Codes: G01B 11/00 Measuring arrangements characterised by the use of optical techniques
• CPC Class Codes: G01N 21/8806 Specially adapted optical and illumination features
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

An illumination system and method for providing wide angle illumination to objects to be inspected. The illumination system includes a dome light array having a plurality of rows where each row includes a plurality of lamps arranged in an arc about an imaging area (so that each lamp in the row is approximately the same distance from the imaging area) and all of the lamps in a row point to and illuminate the same point within the image area. The illumination system can include an aperture in the top of the dome light array through which a camera can image the object. Positioning each row of lamps in an arc about the image point provides various illumination angles to give a relatively uniform wide angle, yet intense, illumination to enhance automated PWB defect inspection. To further provide illumination, a pair of side panel light arrays having a plurality of lamps can be attached to the sides of the dome light array so that the side lamps provide further vertical illumination on the image area from a horizontal side plane.

Claims

1. An illumination system capable of providing wide angle illumination to an image area on an image plane within an interior of the illumination system, comprising:

a partially-cylindrical dome frame having a geometry defined by a radius beginning at an image axis on the image plane so as to form a partial cylinder about the image axis; and

a plurality of light sources coupled to the dome frame so that each light source is approximately the same distance from the image axis, the plurality of light sources positioned such that a central ray of light from each light source strikes approximately the image axis within the image area.

2. The system of claim 1, further comprising a side panel light array coupled to the dome light array, comprising:

a pair of side panel frame coupled to the dome frame; and

a plurality of lamps coupled to each side panel frame and positioned so as to provide illumination within the interior of the illumination system.

3. The system of claim 1 wherein the plurality of light sources illuminates an illumination area having an image depth about the image axis.

4. The system of claim 2, wherein the plurality of lamps in each side panel light array is arranged in a plurality of vertical rows, and wherein each lamp is positioned such that a lamp central ray from each lamp strikes approximately an image point within the image area.

5. The system of claim 4, wherein each lamp within a single vertical row of lamps is positioned such that all central rays from each lamp in each vertical row of lamps strikes the same image point, and further wherein each lamp is positioned so that the distance each lamp central ray travels is approximately equal.

6. The system of claim 4, further comprising a cylindrical image optics positioned between the each lamp and the image area, and wherein the cylindrical image optics works in conjunction with each lamp so that the light cast by each lamp is a line of light through the entire image depth.

7. The system of claim 1, further comprising a cylindrical lens image optic positioned between each light source and the image area to provide more focused illumination at the image area from each light source.

8. The system of claim 1, wherein each light source is a light emitting diode having an intensity ranging from 200 to 5000 millicandles and each lamp is a light emitting diode having an intensity ranging from 200 to 5000 millicandles.

9. The system of claim 1, wherein the plurality of light sources provides a cumulative light contribution that overfills the image area.

10. The system of claim 1, further comprising:

a fan; and

a vent cut out of a top cover of the dome light array, wherein the fan and vent coordinate to direct air away from a space between the aperture and the image area.

11. An illumination system capable of providing wide angle illumination to an image area on an image plane within an interior of t he illumination system, comprising:

a dome light array, comprising;

a cylindrical dome frame having a geometry defined by a radius beginning at an image axis on the image plane so as to form a partial circle as viewed along the image axis;

a plurality of light sources coupled to the dome frame so that each light source is approximately the same distance from the image axis, the plurality of light sources positioned such that a central ray of light from each light source points towards the image axis within the image area to illuminate an illumination area that has an image depth about the image axis; and

an aperture in the dome frame; and

a side panel light array coupled to the dome light array, comprising;

a pair of side panel frame coupled to the dome frame; and

a plurality of lamps coupled to each side panel frame an d positioned so at to provide illumination within the interior of the illumination system.

12. The system of claim 11, wherein the plurality of lamps in each side panel light array is arranged in a plurality of vertical rows, and wherein each lamp is positioned such that a lamp central ray from each lamp strikes approximately an image point within the image area.

13. The system of claim 12, wherein each lamp within a single vertical row of lamps is positioned such that all central rays from each lamp in each vertical row of lamps strikes the same image point, and further wherein each lamp is positioned so that the distance each lamp central ray travels is approximately equal.

14. The system of claim 12, further comprising a cylindrical image optics positioned between the each lamp and the image area, and wherein the cylindrical image optics works in conjunction with each lamp so that the light cast by each lamp is a line of light through the entire image depth.

15. The system of claim 11, further comprising a cylindrical lens image optic positioned between each light source and the image area to provide more focused illumination at the image area from each light source.

16. The system of claim 11, wherein the plurality of light sources provides a cumulative light contribution that overfills the image area.

17. The system of claim 11, wherein the dome light array is positioned above the image plane at a clearance distance sufficient to prevent interference with a component an object being inspected during inspection.

18. The system of claim 11, further comprising:

a fan; and

a vent cut out of a top cover of the dome light array,

wherein the fan and vent coordinate to direct air away from a space between the aperture and the image area.

19. An illumination system for providing illumination to an image area on an image plane, comprising:

a partially-cylindrical frame having a geometry defined by a radius beginning at an image axis on the image plane so as to form a partial cylinder about the image axis; and

a plurality of light sources coupled to the cylindrical frame so that each light source is approximately the same distance from the image axis, the plurality of light sources positioned such that a central ray of light from each light source strikes approximately the image axis within the image area.

20. The illumination system of claim 19, wherein the cylindrical frame comprises a series of semicircular sections, wherein each semicircular section is proximate at least one other semicircular section to provide a cylindrical frame in the shape of a partial cylinder about the image axis.

21. The illumination system of claim 19, wherein an illumination area illuminated by the plurality of light sources is a linear illumination area.