Illumination system and method for generating an image of an object

• US 5,519,496 A
• Filed: 01/07/1994
• Issued: 05/21/1996
• Est. Priority Date: 01/07/1994
• Status: Expired due to Fees

• Current Assignee: Applied Intelligent Systems, Inc. (MKS Instruments Incorporated)
• Original Assignee: Applied Intelligent Systems, Inc. (MKS Instruments Incorporated)
• Inventors: Ellison, James F., Borgert, Gerald D., Bartlett, Robert J.
• Primary Examiner(s): Pham, Hoa Q.
• Application Number:
  US08/179,647
• Time in Patent Office: 865 Days
• Field of Search: 356/394, 356/372, 356/375, 356/376, 356/237, 356/240, 250/561, 250/562, 250/563, 250/571, 250/572, 250/223 B, 362/237, 362/249, 362/252, 362/11, 362/33, 362/800, 348/87, 348/94, 348/95, 348/126, 348/131, 382/8, 382/54, 382/55
• US Class Current: 356/394
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01N 21/8806 Specially adapted optical and illumination features

Abstract

An illumination system having a lighting dome, a vertical light source, an image acquisition means, and a light controlling means, a system controller and a three-axis servo system wherein the dome is of unitary printed circuit board construction populated with a plurality of surface mounted light emitting diodes is disclosed. The dome has a first longitudinal axis and is bendable along hinges formed through the circuit board to define a partially enclosed dome having eight octants or sections, each section having an upper and lower tier portion defining a plurality of planar illumination banks, which illuminate an object from 360° around the object and from predetermined angles relative to the first longitudinal axis. The vertical light source, which is a planar printed circuit board populated with surface mounted LEDs, and the beam splitter are provided for illumination of the object with light parallel to the first longitudinal axis. The planar geometry of the illumination banks and the vertical lighting source cause the LEDs to emit light rays that are substantially parallel. The light controlling means controls the intensity of each section and tier portion through pulse width modulation of the respective plurality of light emitting diodes. The acquisition means is provided for acquiring reflected light rays to generate an image of the illuminated object. The increased density of the surface mounted diodes increase the light intensity produced over known illumination systems employing conventional LED mounting techniques. Moreover, the light controlling means can be programmed via the system controller to light any of the panels at a selected intensity. The system controller control the servo system to move the acquisition means in any of three axis so that the acquisition means can capture an image of a preselected area of the object. The system controller processes the captured image to detect a feature of the object.

Claims

1. An apparatus for illuminating an object comprising:

a lighting dome having a longitudinal axis, said dome including a plurality of illumination banks, each one of said banks having at least a first plurality of light emitting means mounted thereon, said first plurality of light emitting means being arranged on said illumination bank to emit substantially parallel light rays toward the object;

a vertical light source having a second plurality of light emitting means mounted thereon, said second plurality of light emitting means being disposed on said vertical light source for emitting substantially parallel light rays coincident with and radially extending from said longitudinal axis;

a beam splitter optically intermediate said dome and said vertical light source for directing light rays in a path coincident with and radially extending from said longitudinal axis through said dome to the surface of the object;

light controlling means coupled with said illumination banks and said vertical light source for causing said first and second pluralities of light emitting means to emit light rays for illuminating the surface of the object; and

,

image acquisition means in optical communication with the surface of the object for capturing light rays reflected from the object in response to the object being illuminated to produce an image of the object.

2. The apparatus of claim 1, wherein said dome includes a top portion substantially perpendicular to said axis and a plurality of longitudinally extending sections circumferentially spaced about said top portion and connected thereto by one of a plurality of first hinges, each one of said plurality of sections having an upper and lower tier portion separated by one of a plurality of second hinges wherein each one of said upper and lower tier portions includes one of said plurality of illumination banks.

3. The apparatus of claim 2, wherein said dome is of unitary printed circuit board (PCB) construction and each first plurality of light emitting means includes a first plurality of light emitting diodes, and wherein each one of said plurality of illumination banks has surface mounted thereto one of said first plurality of light emitting diodes, said pluralities of first and second hinges comprising bend lines formed in the unitary PCB to thereby simplify construction of said dome.

4. The apparatus of claim 2, wherein said dome includes eight sections and wherein said lower tier portion is substantially parallel to said axis and said upper tier portion forms an acute angle with respect to said axis such that the object is obliquely illuminated by light rays.

5. The apparatus of claim 2 further comprising means for reducing a longitudinal distance between said dome and said image acquisition means while maintaining a focal length associated with said image acquisition means.

6. The apparatus of claim 1, wherein said light controlling means is of the type including a continuous mode wherein the intensity of light rays emitted from said illumination banks and said vertical light source is variable from a predetermined minimum to a predetermined maximum intensity level by said light controlling means.

7. The apparatus of claim 6, wherein said light controlling means causes light rays to be emitted from said illumination banks and said vertical light source by applying a respective actuation signal thereto, the intensity of the respective emitted light rays being variable by pulse width modulation of said respective actuation signal by said light controlling means.

8. The apparatus of claim 1, wherein said light controlling means is of the type including a strobe mode wherein the intensity of light rays emitted from said illumination banks and from said vertical light source is equal to said predetermined maximum intensity, said vertical light source emitting light rays for a first predetermined interval, selected ones of said illumination banks on said upper tier portions emitting light rays for a second predetermined interval, and selected ones of said illumination banks on said lower tier portions emitting light rays for a third predetermined interval.

9. The apparatus of claim 1 wherein each one of said first and second pluralities of light emitting means has a nominal wavelength and said acquisition means has a predetermined acquisition bandwidth, said nominal wavelength falling within said predetermined acquisition bandwidth to thereby improve acquisition means gain.