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Laser Ignition and Diagnostic Systems Delivered by Flexible Optical Fibers

Colorado State University

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Publications:

PDF Document Publication09-068.pdf (441 KB)


Technology Marketing Summary

Laser-based ignition systems based on state-of-the-art optical fibers and sophisticated new delivery strategies that provide both engine sparking and diagnostics capabilities.

Description

Due to the large cylinder pressure and mixture density desired in modern engines, traditional spark ignition systems must operate at high voltage levels. As a result, dielectric breakdown (unwanted sparking) and electrode erosion frequently plague modern gas engines and are a limiting factor in the operational envelope of modern gas engines.

Optical sparks suffer from neither of these shortcomings and thus may have significant advantages for improved engine operation. In certain cases, optical sparks can also afford performance benefits associated with extension of maintenance intervals as well as changes in the lean limit, coefficient of variation of pressure, pollutant emissions and other parameters. Laser ignition has been shown to be a particularly effective way of igniting lean mixtures. In fact, it is fairly easy to create a spark by using "open path" laser delivery. The open path method implies that the laser beam propagates through the ambient air and is steered to the desired location by mirrors. Although simple and effective, this system is not practical for most industrial applications. Thus, there is a need for the development of an alternative optical delivery system.

Researchers in the Department of Mechanical Engineering at Colorado State University have developed laser-based ignition systems based on state-of-the-art optical fibers and sophisticated new delivery strategies. It is generally challenging to use optical fibers to deliver laser pulses in a way that allows one to focus the exit (output) pulse to form a spark in the gas-phase. The required breakdown intensity is typically approximately 100-300 GW/cm2. Light intensities of this magnitude require an exit pulse with a sufficient combination of optical power and beam quality (the latter in order to focus the light to a small spatial dimension). To meet this challenge, researchers at Colorado State University have employed state-of-the-art optical fibers and creative new delivery strategies. With four issued U.S. patents, these researchers are at the forefront of this exciting field.

Benefits
  • Laser can be located away from engine unit.
  • One laser can serve multiple cylinders, lowering costs and maintenance.
  • Fiber optic system allows diagnostic light to return for analysis.
Applications and Industries
  • Heavy-duty natural gas engines
  • Other internal combustion engines
  • Engine diagnostics
  • Laser Induced Breakdown Spectroscopy (LIBS)
Patents and Patent Applications
ID Number
Title and Abstract
Primary Lab
Date
Patent 7,412,129
Patent
7,412,129
Fiber coupled optical spark delivery system
A spark delivery system for generating a spark using a laser beam is provided, the spark delivery system including 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. In addition, the laser delivery assembly 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. In accordance with embodiments of the present invention, the assembly may be used to create a spark in a combustion engine. In accordance with other embodiments of the present invention, a method of using the spark delivery system is provided. In addition, a method of choosing an appropriate fiber for creating a spark using a laser beam is also presented.
08/12/2008
Issued
Patent 7,340,129
Patent
7,340,129
Fiber laser coupled optical spark delivery system
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.
03/04/2008
Issued
Patent 7,420,662
Patent
7,420,662
Optical diagnostics integrated with laser spark delivery system
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.
09/02/2008
Issued
Technology Status
Technology IDDevelopment StageAvailabilityPublishedLast Updated
09-068Prototype - Demonstrated in laboratory setting and ready for commercialization.Available - Available for licensing and currently seeking sponsored research opportunities.03/07/201203/07/2012

Contact CSU About This Technology

To: Jeremy Nelson<jeremy.nelson@colostate.edu>