Method and apparatus for detecting embedded material within an interaction region of a structure

• US 7,492,453 B2
• Filed: 09/25/2007
• Issued: 02/17/2009
• 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): EVANS, FANNIE L
• Application Number:
  US11/861,184
• Publication Number:
  US 20080067331A1
• Time in Patent Office: 511 Days
• Field of Search: 356/318, 219/121.61, 219/121.62
• US Class Current: 356/318
• 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 system and method processes a structure comprising embedded material. The system includes a laser adapted to generate light and to irradiate an interaction region of the structure. The system further includes an optical system adapted to receive light from the interaction region and to generate a detection signal indicative of the presence of embedded material in the interaction region. The system further includes a controller operatively coupled to the laser and the optical system. The controller is adapted to receive the detection signal and to be responsive to the detection signal by selectively adjusting the laser.

Claims

1. An optical system for detecting embedded material in a structure, the optical system comprising:

a lens positioned to receive light emitted from an interaction region of the structure during irradiation of the interaction region with laser light;

an optical fiber optically coupled to the lens; and

an analyzer optically coupled to the optical fiber, the analyzer responsive to light indicative of the embedded material within the interaction region.

2. The optical system of claim 1, wherein the analyzer is responsive to the light indicative of the embedded material within the interaction region by generating a detection signal.

3. The optical system of claim 1, wherein the analyzer comprises:

an input slit adapted to receive light from the optical fiber;

an optical grating adapted to receive light from the input slit and to separate the light into a spectrum of wavelengths;

a lens adapted to receive a selected range of wavelengths of the separated light from the optical grating; and

a light sensor adapted to receive the selected range of wavelengths and to generate a signal corresponding to an intensity of the received light.

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

5. The optical system of claim 1, wherein the analyzer further comprises at least one neutral density filter.

6. The optical system of claim 1, wherein the lens is coaxial with the laser light.

7. The optical system of claim 1, wherein the lens is off-axis with the laser light.

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

9. The optical system of claim 1, wherein the analyzer is further adapted to analyze light at a plurality of wavelengths by calculating a spectral ratio characteristic of detection or non-detection of the embedded material.

10. A method of avoiding substantially damaging embedded material within a laser-irradiated interaction region of a structure comprising the embedded material, the method comprising:

processing the structure by irradiating the interaction region with laser light;

collecting light from the interaction region during the irradiation of the interaction region;

monitoring the collected light for a specific wavelength of light associated with the embedded material during the irradiation of the interaction region;

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

selectively adjusting the processing of the structure in response to the indications.

11. The method of claim 10, wherein processing the structure comprises drilling the structure.

12. The method of claim 10, wherein the collected light is generated while processing the structure.

13. The method of claim 10, wherein the structure comprises concrete and the embedded material comprises rebar.

14. The method of claim 10, wherein analyzing at least a portion of the collected light comprises separating the collected light into a spectrum of wavelengths and analyzing at least a portion of the spectrum for indications of the embedded material.

15. The method of claim 10, wherein analyzing at least a portion of the collected light comprises monitoring discrete changes in interactions between material in the interaction region and the laser light using a coupled capacitance discharge (CCD) camera.

25. The method of claim 10, wherein collecting light comprises using a lens coupled to an optical fiber, the lens positioned to receive light emitted from the interaction region of the structure during the irradiation of the interaction region.

16. A laser system for processing a structure comprising embedded material, the laser system comprising:

a laser adapted to generate light and to irradiate an interaction region of the structure;

an optical system adapted to receive light from the interaction region and, during the irradiation of the interaction region, to monitor a specific wavelength of light associated with the embedded material and to generate a detection signal indicative of the presence of the embedded material in the interaction region; and

a controller operatively coupled to the laser and the optical system, the controller adapted to receive the detection signal, the controller responsive to the detection signal by selectively adjusting the laser.

17. The laser system of claim 16, wherein the optical system comprises an analyzer adapted to separate the light received from the interaction region into a spectrum of wavelengths, to analyze at least a portion of the spectrum, and to generate the detection signal in response to the at least a portion of the spectrum.

18. The laser system of claim 16, wherein the optical system comprises a coupled capacitance discharge (CCD) camera.

26. The laser system of claim 16, further comprising a lens and an optical fiber optically coupled to the lens, the lens positioned to receive light emitted from the interaction region of the structure during the irradiation of the interaction region.

19. A processing system for removing material from a structure comprising embedded material, the processing system comprising:

a source of energy waves adapted to impinge an interaction region of the structure with the energy waves;

an analyzer adapted to receive light from the interaction region and, during the impingement of the interaction region, to monitor a specific wavelength of light associated with the embedded material and to generate a detection signal indicative of the presence of the embedded material in the interaction region; and

a controller operatively coupled to the source and the analyzer, the controller adapted to receive the detection signal, the controller responsive to the detection signal by selectively adjusting the source.

20. The processing system of claim 19, wherein the structure comprises concrete and the embedded material comprises rebar.

21. The processing system of claim 19, wherein the optical system comprises a coupled capacitance discharge (CCD) camera.

27. The processing system of claim 19, further comprising a lens and an optical fiber optically coupled to the lens and the analyzer, the lens positioned to receive light emitted from the interaction region of the structure during the impingement of the interaction region.

22. A method of processing a structure comprising embedded material, the method comprising:

irradiating an interaction region of the structure with laser light;

collecting light from the interaction region during the irradiation of the interaction region;

monitoring the collected light for a specific wavelength of light associated with the embedded material during the irradiation of the interaction region;

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

selectively adjusting the processing of the structure in response to the indications.

23. The method of claim 22, wherein the collected light is generated while irradiating the interaction region.

24. The method of claim 22, wherein the structure comprises concrete and the embedded material comprises rebar.

28. The method of claim 22, wherein collecting light comprises using a lens coupled to an optical fiber, the lens positioned to receive light emitted from the interaction region of the structure during the irradiation of the interaction region.