Fiber optical apparatus and system for in situ laser plasma spectroscopy

• US 7,016,035 B2
• Filed: 09/25/2003
• Issued: 03/21/2006
• Est. Priority Date: 09/25/2003
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Wu, Pingfan, Rozier, Elena, Benicewicz, Pamela
• Primary Examiner(s): EVANS, FANNIE L
• Application Number:
  US10/605,371
• Publication Number:
  US 20050068524A1
• Time in Patent Office: 908 Days
• Field of Search: 356/316, 356/318
• US Class Current: 356/318
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0208 using focussing or collimating elements, e.g. lenses or mirrors; performing aberration correction
• CPC Class Codes: G01J 3/0218 using optical fibers
• CPC Class Codes: G01J 3/0232 using shutters
• CPC Class Codes: G01N 21/718 Laser microanalysis, i.e. with formation of sample plasma

Abstract

In in-situ laser plasma spectroscopy (LPS) apparatus includes an enclosure for housing a laser energy source and associated signal coupling optics. A main fiber is attached to the enclosure at a first end of the main fiber, and attached to a probe at a second end of the main fiber. The main fiber is configured for transmitting input laser energy from the laser energy source to a target and for transmitting laser induced plasma emission signals back from the target. The probe has a single focal lens for directing the input laser energy from the main fiber to the target, and for directing the laser induced plasma emission signals from the target to the main fiber.

Claims

1. An in-situ laser plasma spectroscopy (LPS) apparatus, comprising:

an enclosure for housing a laser energy source;

a main fiber connected to said enclosure at a first end of said main fiber, and connected to a probe at a second end of said main fiber, said main fiber configured for transmitting input laser energy from said laser energy source to a target and for transmitting laser induced plasma emission signals back from said target; and

said probe being moveable with respect to said target and having a single focal lens, said input laser energy from said main fiber being focused to said target by movement of said probe for directing said laser induced plasma emission signals from said target to said main fiber.

2. The LPS apparatus of claim 1, wherein said enclosure further includes a beam splitter for directing said input laser energy from said laser energy source into said main fiber, said beam splitter further configured for directing said laser induced plasma emission signals from said main fiber to a second fiber in communication with said enclosure, wherein said second fiber is configured to transmit said laser induced plasma emission signals to a spectrometer device for analysis of said laser induced plasma emission signals.

3. The LPS apparatus of claim 2, wherein said enclosure further includes:

a first lens for focusing said input laser energy reflected from said beam splitter into said main fiber; and

a second lens for focusing said laser induced plasma emission signals directed from said beam splitter into said second fiber.

4. The LPS apparatus of claim 3, wherein said second lens is positioned equidistant between said main fiber and said second fiber.

5. The LPS apparatus of claim 4, wherein said second lens has a focal length of about 100 millimeters.

6. The LPS apparatus of claim 2, wherein said beam splitter further comprises one of a short wavelength pass filter and a band-reflection filter.

7. The LPS apparatus of claim 1, wherein said enclosure comprises a sealed enclosure.

8. The LPS apparatus of claim 1, wherein said probe further comprises a stop at one end thereof, said stop configured such that an exit end of said probe corresponds to a focal point of said single focal lens.

9. The LPS apparatus of claim 8, wherein said single focal lens has a focal length of about 12 millimeters.

10. The LPS apparatus of claim 8, wherein said probe further comprises a depressible shutter for manually unblocking the emergence of input laser energy from said probe.

11. The LPS apparatus of claim 8, wherein said probe further comprises an indicator for indicating said laser energy source is turned on.

12. An in-situ laser plasma spectroscopy (LPS) apparatus, comprising:

an enclosure for housing a laser energy source;

a main fiber connected to said enclosure at a first end of said main fiber, and connected to a probe at a second end of said main fiber, said main fiber configured for transmitting input laser energy from said laser energy source to a target and for transmitting laser induced plasma emission signals back from said target;

said probe having a single focal lens for directing said input laser energy from said main fiber to said target, and for directing said laser induced plasma emission signals from said target to said main fiber; and

at least one satellite fiber attached within said probe, said at least one satellite fiber configured so as to transmit a portion of laser induced plasma emission signals back from said target.

13. The LPS apparatus of claim 12, wherein said enclosure further includes a beam splitter for directing said input laser energy from said laser energy source into said main fiber, said beam splitter further configured for directing said laser induced plasma emission signals from said main fiber to a second fiber connected to said enclosure, wherein said second fiber is configured to transmit said laser induced plasma emission signals to a spectrometer device for analysis of said laser induced plasma emission signals.

14. The LPS apparatus of claim 13, wherein said enclosure further includes:

a first lens for focusing said input laser energy reflected from said beam splitter into said main fiber; and

a second lens for focusing said laser induced plasma emission signals directed from said beam splitter into said second fiber.

15. The LPS apparatus of claim 14, wherein said second lens is positioned equidistant between said main fiber and said second fiber.

16. The LPS apparatus of claim 15, wherein said second lens has a focal length of about 100 millimeters.

17. The LPS apparatus of claim 13, wherein said beam splitter further comprises one of a short wavelength pass filter and a band-reflection filter.

18. The LPS apparatus of claim 12, wherein said enclosure comprises a sealed enclosure.

19. The LPS apparatus of claim 12, wherein said probe further comprises a stop at one end thereof, said stop configured such that an exit end of said probe corresponds to a focal point of said single focal lens.

20. The LPS apparatus of claim 19, wherein said single focal lens has a focal length of about 12 millimeters.

21. The LPS apparatus of claim 19, wherein said probe further comprises a depressible shutter for manually unblocking the emergence of input laser energy from said probe.

22. The LPS apparatus of claim 19, wherein said probe further comprises an indicator for indicating said laser energy source is turned on.

23. The LPS apparatus of claim 19, wherein said probe further comprises a connector, said connector configured to maintain said at least one satellite fiber and said main fiber in a linear arrangement.

24. The LPS apparatus of claim 19, wherein said probe further comprises a connector, said connector configured to maintain said at least one satellite fiber and said main fiber in a hexagonal arrangement.

25. An in-situ laser plasma spectroscopy (LPS) system, comprising:

an enclosure for housing a laser energy source;

a main fiber connected to said enclosure at a first end of said main fiber, and connected to a probe at a second end of said main fiber, said main fiber configured for transmitting input laser energy from said laser energy source to a target and for transmitting laser induced plasma emission signals back from said target;

said probe being moveable with respect to said target and having a single focal lens, said input laser energy from said main fiber being focused to said target by movement of said probe for directing said laser induced plasma emission signals from said target to said main fiber;

a beam splitter disposed within said enclosure, said beam splitter configured for directing said input laser energy from said laser energy source into said main fiber, said beam splitter further configured for directing said laser induced plasma emission signals from said main fiber to a second fiber connected to said enclosure;

a spectrometer device attached to said second fiber, said spectrometer device configured to receive said laser induced plasma emission signals for analysis of said laser induced plasma emission signals;

an intensified charge-coupled device (ICCD) camera attached to said spectrometer device; and

a computer in communication with said ICCD camera.

26. The LPS system of claim 25, wherein said enclosure further includes:

a first lens for focusing said input laser energy reflected from said beam splitter into said main fiber; and

a second lens for focusing said laser induced plasma emission signals directed from said beam splitter into said second fiber.

27. The LPS system of claim 26, wherein said second lens is positioned equidistant between said main fiber and said second fiber.

28. The LPS system of claim 27, wherein said second lens has a focal length of about 100 millimeters.

29. The LPS system of claim 25, wherein said beam splitter further comprises one of a short wavelength pass filter and a band-reflection filter.

30. The LPS system of claim 25, wherein said enclosure comprises a sealed enclosure.

31. The LPS system of claim 25, wherein said probe further comprises a stop at one end thereof, said stop configured such that an exit end of said probe corresponds to a focal point of said single focal lens.

32. The LPS system of claim 31, wherein said single focal lens has a focal length of about 12 millimeters.

33. The LPS system of claim 31, wherein said probe further comprises a depressible shutter for manually unblocking the emergence of input laser energy from said probe.

34. The LPS system of claim 31, wherein said probe further comprises an indicator for indicating said laser energy source is turned on.

35. The LPS system of claim 25, wherein said main fiber is removably connectable to said enclosure and said probe, and said second fiber is removably connectable to said enclosure and said spectrometer through an associated fiber connector.

36. The LPS system of claim 25, wherein said second fiber has a same core size as said main fiber.

37. The LPS system of claim 25, wherein said second fiber further comprises a fiber bundle having a plurality of individual fibers, wherein said individual fibers are arranged in a circular configuration at the connection to said enclosure and arranged in a linear configuration at the connection to said spectrometer.

38. The LPS system of claim 25, further comprising at least one satellite fiber in communication with said probe, said at least one satellite fiber configured so as to transmit a portion of laser induced plasma emission signals back from said target.

39. The LPS system of claim 38, further comprising a shuttering system for blocking said input laser energy from said target upon detection of detection of one or more selected wavelengths from said laser induced plasma emission signals.

40. The LPS system of claim 39, wherein said shuttering system further comprises:

a photomultiplier tube (PMT) detector for receiving a portion of laser induced plasma emission signals; and

a shutter disposed within said enclosure;

wherein said PMT detector is configured to engage said shutter closed upon detecting a threshold level of said one ore more selected wavelengths from said laser induced plasma emission signals.

41. The LPS system of claim 40, wherein said shuttering system further comprises:

a collimating lens for receiving said laser induced plasma emission signals from said satellite fiber; and

a narrow band pass filter for receiving collimated plasma emission signals from said collimating lens.

42. The LPS system of claim 25, wherein said enclosure for housing said laser energy source, said second fiber, said spectrometer device, said ICCD camera and said computer are enclosed within a transportable, vibration damped case.