Method and apparatus for reducing the unwanted effects of noise present in a three dimensional color imaging system

• US 5,701,173 A
• Filed: 02/20/1996
• Issued: 12/23/1997
• Est. Priority Date: 02/20/1996
• Status: Expired due to Term

• Current Assignee: National Research Council Canada
• Original Assignee: National Research Council Canada
• Inventors: Rioux, Marc
• Primary Examiner(s): Hantis, K.
• Application Number:
  US08/603,422
• Time in Patent Office: 672 Days
• Field of Search: 356/375, 356/376, 356/73, 356/402, 356/407, 356/425, 356/300, 356/326, 356/328
• US Class Current: 356/73
• CPC Class Codes: G01B 11/24 for measuring contours or curvatures

Abstract

A method and apparatus is provided that lessens the unwanted effects of noise present at the input of an imaging system. By tapping a small portion of a laser input signal containing wavelengths of light corresponding to red, blue, and green of light used to scan the surface to be imaged, the tapped signal is used to generate three beams that correspond to the red, blue, and green content of the laser input signal. Signals generated at the output of the system that correspond to the color of the scanned surface are normalized with the signals that correspond to the three beams generated by the tapped signal. The normalized output signal indicative of the color of the surface is noise reduced; substantially most of any noise present at the input is eliminated from the output of the device.

Claims

1. A method of determining the color and profile of a target surface comprising the steps of:

(a) providing a beam of light containing a plurality of wavelengths wherein at least one wavelength is well defined;

(b) separating the beam of light into a first beam and a second beam;

(c) providing at least a portion of the second beam to means for detecting information related to the spectral content of the beam, and for generating signals representative of the information related spectral content of the second beam;

(d) scanning the target surface with the first beam of light;

(e) providing at least a portion of the first beam that has reflected from the target surface to a means for detecting information related to the spectral content of the first beam;

(f) generating signals representative of the spectral content of scattered light from the surface;

(g) determining as a function of the signals generated in step (c) representative of the spectral content of the second beam and the signals representative of the spectral content of light scattered from the surface generated in step (f), normalized values representative of the color of the surface; and

,

(h) detecting the profile of the surface from at least a portion of the first beam.

2. A method of determining the color and profile of a target surface comprising the steps of:

(a) providing a beam of light containing a plurality of wavelengths, including at least one well defined wavelength;

(b) separating the beam of light into a first beam and a second beam, the first and second beams containing substantially the same ratio of red, green and blue light;

(c) providing at least a portion of the second beam to a means for detecting the red, green and blue content of the beam, and for generating signals representative of the red, green, and blue content of the second beam;

(d) scanning the target surface with the first beam of light;

(e) providing at least a portion of the first beam that has reflected from the target surface to a means for detecting the red, green and blue content of the first beam;

(f) generating signals representative of the color of the surface;

(g) determining as a function of the signals generated in step (c) representative of the color of the second beam and the signals representative of the color of the surface generated in step

(f), normalized values representative of the color of the surface; and

,

(h) detecting the profile of the surface from at least a portion of the first beam.

3. An optical apparatus for determining the color and profile of a target surface comprising:

(a) means for generating a beam of light containing a plurality of wavelengths, including at least one well defined wavelength;

(b) means for separating the beam of light into a first beam and a second beam; and

for generating signals representative of the red, green, and blue content of the second beam;

(d) scanning means for scanning the target surface with the first beam of light;

(e) means for detecting the profile of the target surface and for detecting the red, green and blue content of the first beam and for generating signals representative of the color of the surface; and

(f) means for determining as a function of the signals generated in step (c) representative of the color of the second beam and the signals representative of the color of the surface generated in step (e), normalized values representative of the color of the surface.

4. An optical apparatus as defined in claim 3, wherein the means for separating the beam of light into a first beam and a second beam is a beam splitter that allows a portion of the beam to pass therethrough, and reflects a portion of the beam in a manner such that the spectral content of the first and second beam is substantially identical.

5. An optical apparatus as defined in claim 4, wherein the means for detecting the red, blue and green content of the beams comprises means for separating the beam into three beams of three different primary wavelengths corresponding to red, blue, and green, and means for detecting the intensity of each of the three beams.

6. An optical apparatus as defined in claim 5, wherein the means for detecting the intensity comprise three photodetectors.

7. An optical apparatus as defined in claim 6, wherein the photodetectors are substantially identical.

8. An optical apparatus as defined in claim 3, wherein the means defined in step (f) for determining as a function of the signals generated in step (c) representative of the color of the second beam and the signals representative of the color of the surface generated in step (e), normalized values representative of the color of the surface, comprise a suitably programmed processor.

9. An optical apparatus for determining the color and profile of a target surface comprising the steps of:

(a) means for providing a beam of light containing a plurality of wavelengths wherein at least one wavelength is well defined;

(b) means for separating the beam of light into a first beam and a second beam;

(c) means for detecting information related to the spectral content of the second beam, and for generating signals representative of the information related to the spectral content of the second beam;

(d) means for scanning the target surface with the first beam of light;

(e) means for detecting information related to the spectral content of the first beam after it has reflected off the target surface and for generating signals representative of the spectral content of scattered light from the surface;

(f) means for determining as a function of the signals generated in step (c) representative of the spectral content of the second beam and the signals representative of the spectral content of light scattered from the surface generated in step (e), normalized values representative of the color of the surface; and

,

(g) means for detecting the profile of the surface from at least a portion of the first beam.