System and method for detecting laser irradiated embedded material in a structure

• US 7,880,877 B2
• Filed: 09/25/2007
• Issued: 02/01/2011
• Est. Priority Date: 03/18/2003
• Status: Expired due to Fees

• Current Assignee: LOMA Linda University Medical Center (Mission Healthcare Services LLC)
• Original Assignee: LOMA Linda University Medical Center (Mission Healthcare Services LLC)
• Inventors: Denney, Paul E., Huang, Ta-Chieh, Eastman, Jay R.
• Primary Examiner(s): Toatley; Gregory J
• Assistant Examiner(s): PAJOOHI GOMEZ, TARA S
• Application Number:
  US11/861,193
• Publication Number:
  US 20090021731A1
• Time in Patent Office: 1,225 Days
• Field of Search: 356/300, 356/303, 356/305, 356319-320, 356/328, 356/318
• US Class Current: 356/302
• 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 26/034 Observing the temperature of the workpiece
• CPC Class Codes: B23K 26/043 along the beam path, i.e. alignment of laser beam axis relative to laser beam apparatus
• CPC Class Codes: B23K 26/12 in a special atmosphere, e.g. in an enclosure
• CPC Class Codes: B23K 26/123 in an atmosphere of particular gases
• CPC Class Codes: B23K 26/128 Laser beam path enclosures
• CPC Class Codes: B23K 26/142 for the removal of by-products
• 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: G01J 3/02 Details
• CPC Class Codes: G01J 3/0218 using optical fibers
• CPC Class Codes: G01J 3/0291 Housings; Spectrometer accessories; Spatial arrangement of elements, e.g. folded path arrangements
• CPC Class Codes: G01J 3/28 Investigating the spectrum using colour filters G01J3/51

Abstract

A detection system is used during irradiation of an interaction region of a structure with laser light. The structure includes embedded material. The detection system includes means for receiving light emitted from the interaction region. The detection system further includes means for separating the received light into a spectrum of wavelengths. The detection system further includes means for analyzing at least a portion of the spectrum for indications of embedded material within the interaction region.

Claims

1. A system for detecting laser-irradiated embedded material in a structure, the system comprising:

an optical system receiving light emitted from an interaction region of the structure in response to irradiation of the interaction region with laser light that heats material in the interaction region;

a spectral analyzer responsive to at least a portion of the received light by generating a detection signal indicative of the embedded material within the interaction region; and

a controller configured to adjust the laser light irradiating the interaction region in response to the detection signal.

2. The system of claim 1, wherein the optical system comprises a lens receiving light emitted from the interaction region and an optical fiber optically coupled to the lens and to the spectral analyzer.

3. The system of claim 2, wherein the lens is coaxial with the laser light.

4. The system of claim 2, wherein the lens is off-axis with the laser light.

5. The system of claim 1, wherein the spectral analyzer comprises:

an optical grating receiving light from the optical system and to separate the light into a spectrum of wavelengths; and

a light sensor receiving light in at least a portion of the spectrum and to generate a signal corresponding to an intensity of the received light.

6. The system of claim 1, wherein the spectral analyzer comprises a coupled-capacitance discharge (CCD) camera.

7. The system of claim 1, wherein the spectral analyzer comprises at least one neutral density filter.

8. The system of claim 1, wherein the structure comprises concrete and the embedded material comprises rebar.

9. A detection system for use during irradiation of an interaction region of a structure with laser light, the structure comprising embedded material, the detection system comprising:

means for receiving light emitted from the interaction region in response to heating of material in the interaction region by laser irradiation;

means for separating the received light into a spectrum of wavelengths;

means for analyzing at least a portion of the spectrum for indications of embedded material within the interaction region; and

means for adjusting the laser light irradiating the interaction region in response to a signal from said analyzing means.

10. The detection system of claim 9, wherein the receiving means comprises a lens and an optical fiber.

11. The detection system of claim 9, wherein the separating means comprises an optical grating and a light sensor.

12. The detection system of claim 9, wherein the analyzing means comprises a microprocessor operatively coupled to the separating means.

13. The detection system of claim 9, wherein the adjusting means comprises a controller operatively coupled to the analyzing means.

14. A method of detecting rebar in an interaction region of a structure with rebar embedded therein, the interaction region irradiated by laser light, the method comprising:

receiving light emitted from the interaction region in response to laser heating of material in the interaction region;

separating the light into a spectrum of wavelengths;

analyzing at least a portion of the spectrum for indications of rebar within the interaction region; and

adjusting the laser light irradiating the interaction region in response to the irradiation.

15. The method of claim 14, wherein the light is received from the interaction region while the interaction region is irradiated with laser light.

16. The method of claim 14, wherein analyzing the at least a portion of the spectrum comprises monitoring the intensity of light having wavelengths associated with the embedded rebar.

17. The method of claim 14, wherein analyzing the at least a portion of the spectrum comprises monitoring discrete changes in interactions between the laser light and material in the interaction region.