Optical diagnostics integrated with laser spark delivery system

• US 20060037572A1
• Filed: 08/04/2005
• Published: 02/23/2006
• Est. Priority Date: 08/04/2004
• Status: Active Grant

• Current Assignee: Colorado State University Research Foundation (Colorado State University System)
• Original Assignee: Colorado State University Research Foundation (Colorado State University System)
• Inventors: Yalin, Azer, Defoort, Morgan, Willson, Bryan, Collins, George
• Granted Patent: US 7,420,662 B2
• Time in Patent Office: Days
• US Class Current: 123/143.B
• CPC Class Codes: F02D 35/022 using an optical sensor, e.g. in-cylinder light probe
• CPC Class Codes: F02P 17/12 Testing characteristics of the spark, ignition voltage or current testing of sparking plugs H01T13/60
• CPC Class Codes: F02P 23/04 Other physical ignition means, e.g. using laser rays
• CPC Class Codes: G01N 21/718 Laser microanalysis, i.e. with formation of sample plasma
• CPC Class Codes: G01N 2201/08 Optical fibres; light guides

Abstract

A spark delivery system for generating a spark using a laser beam is provided, and includes a laser light source and a laser delivery assembly. The laser delivery assembly includes a hollow fiber and a launch assembly comprising launch focusing optics to input the laser beam in the hollow fiber. The laser delivery assembly further includes exit focusing optics that demagnify an exit beam of laser light from the hollow fiber, thereby increasing the intensity of the laser beam and creating a spark. Other embodiments use a fiber laser to generate a spark. Embodiments of the present invention may be used to create a spark in an engine. Yet other embodiments include collecting light from the spark or a flame resulting from the spark and conveying the light for diagnostics. Methods of using the spark delivery systems and diagnostic systems are provided.

Claims

1. A spark and diagnostic system for an engine, the system comprising:

a laser light source for generating a laser beam;

launch optics for focusing said laser beam;

a laser transmission fiber for receiving said laser beam from said launch optics and transmitting said laser beam; and

exit focusing optics for receiving said laser beam from said laser transmission fiber and focusing said laser beam for generating a spark in a fuel and air mixture within the engine;

wherein said laser transmission fiber transmits diagnostic light generated from at least one of said spark or from a flame from combustion of the fuel and air mixture.

2. The system as claimed in claim 1, wherein said laser transmission fiber comprises a hollow bore and a wall surrounding said hollow bore.

3. The system as claimed in claim 1, further comprising a window allowing optical communication of the diagnostic light to the laser transmission fiber.

4. The system as claimed in claim 1, further comprising a multiplexer located between said laser light source and said exit focusing optics.

5. The system as claimed in claim 1, further comprising a diagnostic apparatus for analyzing said diagnostic light from said laser transmission fiber.

6. The system as claimed in claim 5, further comprising a dichroic mirror located between said exit focusing optics and said diagnostic apparatus, wherein at least a portion of said laser beam passes through said dichroic mirror before generating said spark in the engine, and wherein at least a portion of the diagnostic light is reflected off said dichroic mirror and conveyed to said diagnostic apparatus.

7. The system as claimed in claim 6, wherein said dichroic mirror comprises a cold mirror.

8. The system as claimed in claim 6, further comprising at least one of a dispersive element or a band-pass filter between said dichroic mirror and said diagnostic apparatus.

9. The system as claimed in claim 5, wherein said diagnostic apparatus is selected from the group consisting of a circuit and a computer.

10. The system as claimed in claim 1, wherein at least one of said launch optics and said exit focusing optics comprises at least one lens.

11. The system as claimed in claim 1, wherein at least one of said launch optics and said exit focusing optics comprises at least one curved mirror.

12. The system as claimed in claim 1, wherein at least one of said launch optics and said exit focusing optics are selected from the group consisting of diffractive optics, adaptive optics, and a combination thereof.

13. A diagnostic system for an engine, the engine including a cylinder for containing a fuel and air mixture to be ignited, the system comprising:

a means for generating a laser beam;

a fiber optic means for conveying said laser beam;

a means for focusing the laser beam to generate a spark and ignite the fuel and air mixture within the cylinder;

a means for transmitting diagnostic light from the cylinder, the diagnostic light comprising light from at least one of said spark or a flame from combustion of the fuel and air mixture; and

a means for performing diagnostic analysis of said diagnostic light.

14. The system as claimed in claim 13, further comprising a means for transmitting and reflecting, wherein said means for transmitting and reflecting transmits said laser beam and reflects said diagnostic light.

15. The system as claimed in claim 14, wherein said laser beam and said diagnostic light from said cylinder traverse a substantially common path between said means for transmitting and reflecting and the cylinder.

16. The system as claimed in claim 14, further comprising an optical fiber between said means for transmitting and reflecting and said means for performing diagnostic analysis, wherein said optical fiber conveys at least a portion of said diagnostic light.

17. The system as claimed in claim 13, wherein said means for performing diagnostic analysis comprises a photodetector.

18. A spark and diagnostic system, comprising:

a means for generating a beam of laser light, wherein said means for generating a beam of laser light is selected from the group consisting of;

(a) a laser source, launch optics, and hollow optic fiber; and

(b) a fiber laser;

a means for focusing the laser light to generate a spark; and

a photodetector means for receiving diagnostic light from at least one of the spark or a flame resulting from the spark.

19. The system as claimed in claim 18, wherein said means for focusing the laser light is selected from the group consisting of diffractive optics, active optics, adaptive optics, and a combination thereof.

20. The system as claimed in claim 18, further comprising a means for separating the wavelengths of said diagnostic light.

21. The system as claimed in claim 20, wherein said means for separating comprises at least one device selected from the group consisting of a prism, a diffraction grating, a monochromator, a spectrometer, an optical multi-channel analyzer, and an optical band-pass filter.

22. The system as claimed in claim 18, wherein said photodetector means for receiving comprises at least one device selected from the group consisting of a photodiode, a phototransistor, an avalanche photodiode, a photomultiplier tube, a complementary metal oxide semiconductor, a charge-coupled device, an intensified charge-coupled device, and a contact image sensor.

23. The system as claimed in claim 18, wherein said means for focusing the laser light is in optical communication with an engine cylinder.

24. The system as claimed in claim 18, wherein a diagnostics performed by the system comprises at least one of a spark formation, an optical intensity, a LIBS, an element analysis, a pollutant analysis, an OES, a cycle measurement, a temperature analysis, a pressure sensing, an exhaust emissions analysis, an ion-sensing, a knock indicator, a buildup analysis, and a contaminant monitoring.

25. The system as claimed in claim 18, further comprising a multiplexer located between said means for generating and said means for focusing.

26. A method of generating a spark and collecting a diagnostic light, the method comprising:

providing a beam of laser light using a laser generator and conveyance apparatus, the laser generator and conveyance apparatus comprising at least one of either a hollow optic fiber or a fiber laser;

focusing the laser light to generate a spark in a fuel and air mixture; and

receiving a diagnostic light from at least one of the spark or a flame resulting from combustion of the fuel and air mixture.

27. The method as claimed in claim 26, further comprising substantially cleaning a window proximate a location of the fuel and air mixture.

28. The method as claimed in claim 26, further comprising multiplexing the laser light to a plurality of spark targets.

29. The method as claimed in claim 26, further comprising providing a photodetector for said receiving of the diagnostic light.

30. The method as claimed in claim 29, further comprising providing a dispersive element for separating a wavelength of the diagnostic light prior to said receiving the diagnostic light.