Color sensing for laser decoating

• US 9,375,807 B2
• Filed: 11/12/2013
• Issued: 06/28/2016
• Est. Priority Date: 01/09/2004
• Status: Active Grant

• Current Assignee: General Lasertronics Corporation
• Original Assignee: General Lasertronics Corporation
• Inventors: Thomas, James W., Wool, Mitchell R.
• Primary Examiner(s): Heinrich, Samuel M
• Application Number:
  US14/078,332
• Publication Number:
  US 20140069897A1
• Time in Patent Office: 959 Days
• Field of Search: 219/121.62, 219/121.68, 219/121.69, 219/121.83
• US Class Current: 1/1
• CPC Class Codes: B23K 2103/172 wherein at least one of the layers is non-metallic
• CPC Class Codes: B23K 26/03 Observing, e.g. monitoring, the workpiece
• CPC Class Codes: B23K 26/032 using optical means
• CPC Class Codes: B23K 26/04 Automatically aligning, aiming or focusing the laser beam, e.g. using the back-scattered light
• CPC Class Codes: B23K 26/08 Devices involving relative movement between laser beam and workpiece
• CPC Class Codes: B23K 26/082 Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head
• CPC Class Codes: B23K 26/16 Removal of by-products, e.g. particles or vapours produced during treatment of a workpiece by a fluid stream B23K26/142
• CPC Class Codes: B23K 26/36 Removing material B23K26/55, B23K26/57 take precedence
• CPC Class Codes: B23K 26/361 for deburring or mechanical trimming B23K26/351 takes precedence
• CPC Class Codes: B23K 26/40 taking account of the properties of the material involved

Abstract

A coating removal apparatus utilizing a common optics path to provide laser pulses to a coated surface and to direct a light illumination reflected from the coated surface to a photosensitive detector and analyzer. The apparatus is an integrated device including a laser source, a beam splitter, scanning optics, a waste removal apparatus, one or more light illuminators, a photosensitive detector, a comparator, and a control logic circuit. Alternatively, the laser source is external to the integrated device and a fiber optic cable is used to connect the laser source to the integrated device.

Claims

1. A laser-based coating removal system to remove a coating from a surface, the system comprising:

a. a laser source to provide a laser pulse;

b. scanning optics to direct the laser pulse along a laser path to a first position on the surface, whereby the laser pulse impinges the first position on the surface thereby ablating a portion of the coating from the first position;

c. one or more light illuminators to provide a light illumination, each light illumination along a light illumination path, the light illumination impinging the first position on the surface;

d. a photosensitive detector to receive light reflected from the surface as a result of the impinging light illumination and to measure the reflected light; and

e. a color sensing path to direct the reflected light from the surface to the photosensitive detector, wherein the color sensing path includes the scanning optics, wherein all of the color sensing path is independent of all of the light illumination path.

2. The system of claim 1 further comprising a control logic circuit coupled to the laser source, the scanning optics, and to the photosensitive detector, wherein the control logic circuit provides control signals to the laser source and the scanning optics.

3. The system of claim 2 further comprising a comparator coupled to the photosensitive detector to compare the measured reflected light with predetermined parameters to determine if the coating is removed from the first position on the surface.

4. The system of claim 3 wherein the control logic circuit provides a first control signal to the scanning optics to direct the laser pulse to the first position on the surface if it is determined that the coating is not removed from the first position.

5. The system of claim 4 wherein the first position and each successive position on the surface is determined according to a coating removal pattern.

6. The system of claim 5 wherein if it is determined that the coating is not removed from the first position, or each successive position, then the control logic circuit maintains a record list of each position at which the coating is not removed such that an additional laser pulse is directed to each position listed in the record list.

7. The system of claim 1 wherein the scanning optics include one or more reflecting scanners.

8. The system of claim 7 wherein the one or more reflecting scanners comprise a lens and mirror array.

9. The system of claim 1 wherein the scanning optics include one or more refracting scanners.

10. The system of claim 9 wherein the one or more refracting scanners comprise a lens and prism array.

11. The system of claim 1 wherein the scanning optics include focusing optics.

12. The system of claim 1 further comprising a beam splitter to direct the reflected light away from the laser path and toward the photosensitive detector.

13. The system of claim 1 wherein the one or more light illuminators provide the light illumination directly to the surface.

14. The system of claim 1 further comprising an optical fiber coupled between the laser source and the scanning optics to provide the laser pulse from the laser source to the scanning optics.

15. The system of claim 1 wherein the one or more light illuminators comprises a single wide spectrum illuminator.

16. The system of claim 15 wherein the photosensitive detector comprises a single sensor to measure a relative lightness of the surface.

17. The system of claim 15 wherein the photosensitive detector comprises a spectrophotometer sensor to measure the reflectance at a plurality of different wavelengths.

18. The system of claim 1 wherein the one or more light illuminators comprises a red spectrum illuminator to provide a red light illumination and a blue spectrum illuminator to provide a blue light illumination.

19. The system of claim 18 wherein the photosensitive detector temporally separates a reflected red light resulting from the impinging red spectrum illumination and a reflected blue light resulting from the impinging blue spectrum illumination.

20. The system of claim 1 further comprising a waste collection mechanism to collect an ablated portion of the surface.

21. A coating removal system to remove a coating from a surface, the integrated device comprising:

a. a laser source to provide a laser pulse;

b. scanning optics to direct the laser pulse along a laser path to a first position on the surface, whereby the laser pulse impinges the first position on the surface thereby ablating a portion of the coating from the first position;

c. one or more light illuminators to provide a light illumination, each light illumination along a light illumination path, the light illumination impinging the first position on the surface;

d. a photosensitive detector to receive light reflected from the surface as a result of the impinging light illumination and to measure the reflected light; and

e. a color sensing path to direct the reflected light from the surface to the photosensitive detector, wherein the color sensing path includes the scanning optics, wherein all of the color sensing path is independent of all of the light illumination path.

22. The integrated device of claim 21 further comprising a waste collection mechanism to collect the ablated portion of the surface.

23. The integrated device of claim 21 further comprising a control logic circuit coupled to the laser source, the scanning optics, and to the photosensitive detector, wherein the control logic circuit provides control signals to the laser source and the scanning optics.

24. The integrated device of claim 21 wherein the scanning optics include one or more reflecting scanners.

25. The integrated device of claim 21 wherein the scanning optics include one or more refracting scanners.

26. The integrated device of claim 21 further comprising a beam splitter to direct the reflected light away from the laser path and toward the photosensitive detector.

27. A coating removal system to remove a coating from a surface, the system comprising:

a. a laser source to provide a laser pulse;

b. scanning optics to direct the laser pulse along a laser path to a first position on the surface, whereby the laser pulse impinges the first position on the surface thereby ablating a portion of the coating from the first position;

c. a light illuminator to provide a light illumination along a light illumination path, the light illumination impinging the first position on the surface;

d. a detector to receive and measure light reflected from the surface as a result of the impinging light illumination; and

e. a color sensing path comprising the scanning optics to direct the reflected light from the surface to the detector, wherein all of the color sensing path is independent of all of the light illumination path.