WO2001069136A1 - Allumage laser - Google Patents

Allumage laser Download PDF

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Publication number
WO2001069136A1
WO2001069136A1 PCT/US2000/006255 US0006255W WO0169136A1 WO 2001069136 A1 WO2001069136 A1 WO 2001069136A1 US 0006255 W US0006255 W US 0006255W WO 0169136 A1 WO0169136 A1 WO 0169136A1
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WO
WIPO (PCT)
Prior art keywords
recited
laser
excitation light
light source
ignitor
Prior art date
Application number
PCT/US2000/006255
Other languages
English (en)
Inventor
James W. Early
Charles S. Lester
Original Assignee
The Regents Of The University Of California
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by The Regents Of The University Of California filed Critical The Regents Of The University Of California
Priority to AU2000235236A priority Critical patent/AU2000235236A1/en
Priority to PCT/US2000/006255 priority patent/WO2001069136A1/fr
Publication of WO2001069136A1 publication Critical patent/WO2001069136A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23Q—IGNITION; EXTINGUISHING-DEVICES
    • F23Q13/00—Igniters not otherwise provided for
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
    • F02C7/00—Features, components parts, details or accessories, not provided for in, or of interest apart form groups F02C1/00 - F02C6/00; Air intakes for jet-propulsion plants
    • F02C7/26—Starting; Ignition
    • F02C7/264—Ignition
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02K—JET-PROPULSION PLANTS
    • F02K9/00—Rocket-engine plants, i.e. plants carrying both fuel and oxidant therefor; Control thereof
    • F02K9/95—Rocket-engine plants, i.e. plants carrying both fuel and oxidant therefor; Control thereof characterised by starting or ignition means or arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
    • F02P23/00—Other ignition
    • F02P23/04—Other physical ignition means, e.g. using laser rays
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H01S3/11—Mode locking; Q-switching; Other giant-pulse techniques, e.g. cavity dumping
    • H01S3/1123—Q-switching
    • H01S3/113—Q-switching using intracavity saturable absorbers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
    • H01S3/094049—Guiding of the pump light
    • H01S3/094053—Fibre coupled pump, e.g. delivering pump light using a fibre or a fibre bundle
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
    • H01S3/094076—Pulsed or modulated pumping
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
    • H01S3/094096—Multi-wavelength pumping
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H01S3/102—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling the active medium, e.g. by controlling the processes or apparatus for excitation
    • H01S3/1022—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling the active medium, e.g. by controlling the processes or apparatus for excitation by controlling the optical pumping

Definitions

  • This invention relates to a method and apparatus for laser ignition.
  • pulse from a Q-switched laser is used to initiate fuel ignition by generating high temperatures
  • Fuel combustion zones are usually harsh, mechanically
  • a long duration low peak power pulse from an
  • excitation light source is split and injected into at least two optical fibers.
  • the fiber transports the light into an ignitor laser.
  • the second optical fiber is longer than the first
  • optical fiber and transports a long duration low peak power pulse of the light into a beam
  • output of the ignitor laser is a short duration high peak power pulse because the ignitor laser
  • the combined beam functions as a beam compressor.
  • the combined beam of short duration high peak power
  • delay line is then focused into a focal point in an aerosol spray or cloud of combustible fuel.
  • remote excitation light source is split and injected into at least two optical fibers, one of which
  • the first optical fiber and the second optical fiber both transport light
  • a third optical fiber is
  • the ignitor laser functions as a laser pulse length compressor, the first output of the ignitor laser is a short duration high peak power pulse.
  • the sequenced operation of the ignitor laser provides ignitor
  • Output of the ignitor laser is focused into a focal point in an
  • the ignitor laser outputs a short duration high peak power pulse which
  • the laser to produce a long duration low peak power pulse in the output of the ignitor laser.
  • long duration low peak power pulse is also focused into the focal point in the aerosol spray or
  • excitation light is provided by a laser with at
  • a light source capable of producing more than
  • ignitor laser are sequentially injected into a single optical fiber and transported to the remote
  • the pulse of light with the wavelength which is absorbable by the laser rod is
  • the multiplexing feature is positioned to receive output of a
  • optical fibers which are each connected to an ignitor laser.
  • Figure 1 is a schematic diagram of a first embodiment of the invention employing
  • FIG. 2 is a schematic diagram of a second embodiment of the invention employing a single remote excitation laser to pump an ignitor laser with light pulses which are split into a
  • the beam combiner with the output of the beam combiner being directed into the ignitor laser.
  • Figure 3 is a schematic diagram of a third embodiment of the invention which operates
  • Figure 4 is a schematic diagram of a fourth embodiment of the invention employing a
  • Figure 5 is a schematic diagram of a fifth embodiment of the invention.
  • Figure 6 is a schematic diagram of a multiplexed laser ignition system in accordance
  • FIGS. 7a and 7b are schematic diagrams of two steps of the sequential operation of
  • the invention ignition method utilizes a combination of short and long duration light
  • Dual pulse ignition such as that described in U. S. Patent 5,756,924 can be
  • a single excitation light source is used to
  • the small ignitor laser or lasers provide
  • the light source sustain the air-breakdown plasmas for efficient and stable ignition.
  • the light from the excitation light source serves a dual role: (a) providing light
  • the excitation light source generally is a laser, but may also be a light emitting diode
  • any of a variety of laser systems may be used as an excitation laser light
  • excitation laser light may be generated by a Q-switched, cavity dumped
  • an excitation light source for the fifth embodiment of the invention, an excitation light source
  • Excitation lasers which are active or passive Q-switched can be used
  • third, fourth and fifth embodiments of the invention are active Q-switched solid-state laser
  • a wavelength tunable, Q-switched Cr:LiSAF laser that can be tuned over a
  • wavelength range from about 800 to about 1000 nanometers is presently preferred.
  • output of such a laser can be tuned to a wavelength of 808 nanometers, which is a wavelength
  • nanometers which can also be used to pump a Nd: YAG ignitor laser; or a Ti:sapphire laser.
  • tunable lasers or light emitting diodes or flashlamps can be employed as excitation light sources in the practice of the invention, depending upon specific ignition conditions and the type of ignitor laser employed.
  • the excitation laser may be energized by flashlamps or diodes.
  • the excitation laser may be energized by flashlamps or diodes.
  • thermo-electric may be cooled by any suitable means such as water cooling, air cooling, or thermo-electric
  • the excitation laser can be operated in
  • Pulsed mode is generally preferred for economics of energy.
  • the excitation light source must be operated at a wavelength
  • microns of light are preferred.
  • a peak power of greater than 70 kW is generally sufficient, depending upon the type
  • appropriate for the plasma generation function generally may be anywhere from 10 or fewer
  • excitation laser light pulse lengths in the range between about 50 and about 1 microsecond
  • the beam with differing intensities can be used.
  • the two different wavelengths of light from the excitation light are the two different wavelengths of light from the excitation light
  • the beam or beams from the excitation light source are not split, but are delivered
  • Presently preferred optical fibers are multiple-mode optical fibers, but multiple fiber
  • bundles can also be used for transporting the laser light pulses.
  • Single mode optical fibers are generally not as useful because the smaller fibers cannot carry the high peak power needed.
  • multiple-mode fiber with a core diameter in the range from about 50 microns to about 1
  • millimeter generally can accommodate transport of the typical peak power without damage to
  • optical fiber Multiple-mode fibers with core diameters of about 400 microns are provided.
  • a taper at the input end of the optical fiber can be used to enhance efficiency of light
  • Any suitable device can be used for combining the beams, including, but not limited
  • the ignitor laser needs no pumping diodes or flashlamps because it is pumped by light
  • laser can be a small, durable unit which can withstand a harsh fuel ignition environment.
  • the ignitor laser rod (lasing medium) can be made of any Q-switchable, solid-state
  • neodymium doped yttrium aluminum garnet (Nd: YAG) is presently preferred
  • Nd:YLF neodymium doped yttrium lithium fluoride
  • the resonant cavity of the ignitor laser can be of either stable or unstable configuration
  • the coated optical surface is bounded by light reflective coatings placed upon optical surfaces.
  • the coated optical surface is bounded by light reflective coatings placed upon optical surfaces.
  • surfaces may be curved or flat, depending upon cavity configuration (stable or unstable).
  • first coating can be upon the surface of the collimating lens facing the input end of the ignitor
  • the first coating must be of a
  • dichroic nature that is, highly reflective for lasing wavelengths and highly transmissive for
  • a second coating is generally placed upon the output end of the
  • the size of the ignitor laser rod can vary greatly, depending upon the application.
  • the diameter of the Q-switch is preferably matched to the rod diameter with thickness
  • All components of the ignitor laser can be mounted in a cylindrical tube to become a
  • Metal or ceramic material is generally considered most suitable for
  • the igmtor laser encasement although other materials can be used with good results.
  • ignitor laser rods with a length in the range from 0.5 to no
  • laser to be used for aircraft engine ignition are in the range from 1 to 12 centimeters in length
  • the ignitor laser can be cooled by any suitable means such as air cooling, circulated water cooling, thermal-electric cooling, or use of phase transition material. Air cooling is
  • the ignitor laser be operated in pulsed mode.
  • the ignitor laser is used to produce laser light having temporal lengths or pulse widths
  • wavelengths from as short as 200 nanometers to as long as 12 microns can be effectively used
  • wavelengths in the infrared range from about 700 nanometers to about 3 microns.
  • a short focal length lens is positioned to focus the output of the ignitor laser into the
  • Short focal lengths are generally preferred because the longer the
  • this lens can be anywhere in the range from about 1 cm to about 100 cm, although
  • a focal length in the range from about 5 to about 30
  • a laser window can be used to protect the ignitor laser focal lens from
  • a single excitation light source is used to
  • the light beam from the excitation light source is split can be equal or unequal.
  • the lasing material is pumped, the Q-switch is activated, and the
  • ignitor laser outputs a short duration high peak power pulse of light, typically from about 10
  • the short duration high peak power pulse from the ignitor laser is
  • a fiber optic delay line long enough to delay the beam, generally from about 50 to 100
  • Any suitable device can be used for combining the beams including, but not limited to,
  • the combined beams are then directed through a common focusing lens into a focal
  • focal length is generally preferred because of the high laser light power density achieved
  • length lens is found to be useful for generation of an air breakdown spark by efficient
  • Pulse Sequence single output pulse split into two beams
  • a single excitation light source providing a
  • long duration low peak power pulse is used to pump at least one ignitor laser with split
  • the two portions into which the light beam from the excitation light source is split can be equal or
  • multiple pass delay lines can be used.
  • excitation light source before the combined beams are directed into the ignitor laser.
  • Any suitable device can be used for combining the beams, including, but not limited
  • the combined light beam from the beam combiner having a pulse of long duration low
  • duration low peak power light is focused into an ignitor laser located more proximately to a
  • light from the excitation light source is created by splitting the beam, delaying a portion of the beam, and then recombining the beam so that pulses of it reach the ignitor laser at intervals of
  • the ignitor laser is activated and outputs a short duration high peak power laser light
  • the short duration high peak power laser light pulse from the ignitor laser is focused
  • ignitor laser Because the ignitor laser Q-switch is bleached and has not had time to recover,
  • the ignitor laser simply outputs the same low power long duration pulse received from the
  • excitation laser pulses are used to sequentially Q-switch and gain switch the ignitor laser.
  • pulses is reiterated continuously during the entire time fuel combustion is desired.
  • Pulse Sequence single output pulse split into two beams
  • Pulse Sequence alternating first and second pulses
  • a single excitation light source is used to
  • the excitation laser produces two laser pulses in its output.
  • An optical fiber
  • Output from the ignitor laser is focused into a focal point in the aerosol spray or cloud
  • a first long duration low peak power pulse from the excitation light source is injected
  • ignitor laser provides excitation of the ignitor laser.
  • the ignitor laser subsequently outputs a
  • the ignitor laser Q-switch is bleached and has
  • the ignitor laser simply outputs the same low peak power long duration pulse received from the excitation laser. This long duration low peak power pulse is
  • the two excitation laser in the third embodiment of the invention, the two excitation laser
  • pulses are used to sequentially Q-switch and gain switch the ignitor laser. Sequentially Q-
  • This sequence of alternating pulses is reiterated continuously during the entire time fuel combustion is desired.
  • the temporal duration or pulse width of the first embodiment the temporal duration or pulse width of the first embodiment
  • wavelengths, pulse energies and peak powers for the third embodiment of the invention are set
  • source can be of equal duration and power or they can be different.
  • One particular fuel ignition process for which the third embodiment of the present invention is particularly suitable is achieved by application of two identical, low peak power
  • the passive Q-switch can recover to a high loss state (typically 1 microsecond), the application
  • Energy provided by each ignitor laser pulse is typically about 50 to 100 mJ.
  • the excitation laser in the third embodiment of the invention can provide
  • the first pulse which pumps the ignitor laser may be of very
  • the second excitation laser pulse with a pulse width of only about 10 to 200 nanoseconds is produced to sustain the fuel plasma generated
  • laser and the second pulse from the excitation laser is typically from about 25 to about 200
  • excitation light source more specifically, a laser with a plurality of resonator cavities and
  • a common high reflecting end mirror can be used for two resonating cavities, but
  • the excitation laser will Q-switch when a voltage is quickly
  • the Q-switched pulse which results is directed to and injected
  • fibers can be of equal or unequal peak power, pulse energy, or pulse width.
  • the ignitor laser is pumped by the long
  • the high peak power pulse from the ignitor laser breaks down and ignites the fuel.
  • the long duration low peak power pulse from the excitation laser sustains the breakdown plasma
  • wavelengths, pulse energies and peak powers for the third embodiment of the invention are set
  • Pulse Sequence alternating first and second pulses
  • Pulse Sequence single output pulse from one or more ignitor lasers
  • a laser with an electro-semiconductor from the excitation light source are produced by any suitable means.
  • a laser with an electro-semiconductor from the excitation light source are produced by any suitable means.
  • optic Q-switch is presently preferred for producing the two beams by sequentially operating the laser in free-running and Q-switched modes.
  • Active double Q-switched lasers are
  • excitation light sources for the fifth embodiment of the invention.
  • any other light source capable of producing alternately sequenced beams of two
  • a birefringement filter Brewster plate, prism, or other wavelength selecting device
  • the multimode optical fiber which transports the beam to the ignitor laser.
  • the multimode optical fiber may be a
  • a tapered fiber to facilitate beam alignment or a fiber bundle may be used.
  • the first beam is directed into the laser rod of the ignitor laser to
  • the igmtor laser then outputs a short duration high peak power Q-
  • the ignitor laser is directed through a focusing lens such as that described for the first
  • the second pulse of excitation light passes unimpeded through the ignitor laser and is
  • Pulse Sequence alternating first and second pulses
  • more than one ignitor laser can be used with a
  • ignitors are required for each engine combustion chamber or where multiple combustion
  • ignition lasers with no pumping elements such as flashlamps or diode lasers, and with no
  • electro-optic devices can be built to tolerate the extreme temperature variations and vibrations
  • excitation light sources such as flashlamps or diode lasers in the extreme environments of
  • an optical switching system is used to achieve this multiplexing function.
  • optical fibers with each pair of optical fibers connected to an individual ignitor laser. Any suitable means for optical switching can be used. Electro-optically controlled
  • rotatable prism can be utilized.
  • the lasers can be arranged as shown in the schematic diagram of Figure 1.
  • C ⁇ LiSAF (chromium-doped, lithium-strontium-aluminum fluoride) rod is operated at a
  • the excitation light source laser 10 is pumped by either flashlamps or light emitting
  • the excitation light source laser 10 is operated in a Q-switched mode to produce a
  • long duration (for example, about 100 nanosecond) light pulse at the output of the laser For example, about 100 nanosecond
  • the output of the excitation light source laser J_0 is split into at least two beams by the beam splitter 20. A first portion of the output from the excitation light source laser 10 which
  • first optical fiber 38 400-micron diameter multiple-mode optical fiber is used for the first optical fiber
  • the peak power density of the laser light within the multiple-mode optical fiber 38 is more than a factor of 3 below the threshold for optical damage to the fiber.
  • the excitation light source laser 10 is operated at sufficiently long pulse times to
  • the two long duration pulses from the excitation light source are the two long duration pulses from the excitation light source
  • laser 10 generally have a pulse energy of about 125 mJ and a temporal pulse length from
  • example of the invention is strongly absorbed within the neodymium-doped YAG lasing
  • a lasing condition is quickly established for the ignitor laser cavity within the 50 to
  • the mirrors for the optical resonator of the ignitor laser 50 consist of
  • the optical coating placed upon the rod end is highly transmitting of
  • the coated end of the laser rod 54 is curved to provide
  • the coated surface of the Q-switch 56 is optically
  • the short duration, Q-switched laser pulse (generally having a duration of about 10 to
  • the pulse energy of the laser light at the output of the ignitor laser 50 is calculated to
  • 400-micron diameter multiple-mode optical fiber is also used for the fiber optic
  • the fiber optic delay line 32 is sufficiently longer than the first multiple-mode
  • optical fiber 38 to provide a temporal delay of a number of nanoseconds in the arrival of the
  • a delay of approximately 50 nanoseconds can be
  • Laser light from the fiber optic delay line 32 is collimated using a short focal length
  • a delay of about 25 to about 150 nanoseconds is most useful, depending upon the properties of the fuel to be ignited.
  • a spark breakdown plasma in the fuel spray 72 is formed by the output of the ignitor
  • ignitor laser is pumped is altered to produce two sequential pulses which conform to the selected dual pulse fuel ignition format, thus eliminating the need for a beam combiner between the small ignitor laser and the combustion zone.
  • excitation light source are combined before transportation to the ignitor laser.
  • portion of the laser light is focused by a lens 24 and injected into a first multiple-mode optical
  • a second portion of the excitation light from the beam splitter 20 is reflected by a
  • the fiber optic delay line 32 is longer than the first multiple-
  • the ignitor laser 50 is in the same
  • the first excitation pulse quickly establishes a lasing condition in the laser rod 54
  • excitation pulse re-establishes a lasing condition in the laser rod 54 which results in the
  • the pulse width of the gain-switched pulse is approximately equal to that of the excitation pulse (generally
  • Both laser pulses from the ignitor laser 50 are focused within the fuel by a common
  • the excitation laser K is
  • Example I is used as the excitation light source 10.
  • the two pulses are produced by Q-switching the excitation laser 10 twice within a
  • sequenced pulses separated by a time interval from the excitation laser 10 eliminates the need
  • the temporal length of the two pulses is typically from about 50 to about 200
  • the length of the two pulses can be the same or different.
  • between the two pulses is typically from about 25 to about 2000 nanoseconds.
  • An excitation laser peak power of less than about 200 MW/cm 2 was used.
  • the light pulses 12 from the excitation light source laser 10 are focused through a
  • the multiple-mode optical fiber is about 400 microns and with a taper at the input end.
  • the configuration of the ignitor laser 50 is the same as that described in Example I.
  • the transported laser light output of the optical fiber 38 is focused through another
  • lens 52 into the laser rod 54 of the ignitor laser 50.
  • Any suitable lens capable of uniformly illuminating nearly the full diameter of the input end of the laser rod 54 of the ignitor laser 50 is any suitable lens capable of uniformly illuminating nearly the full diameter of the input end of the laser rod 54 of the ignitor laser 50.
  • the second lens 52 may be a conventional short focal
  • lens length lens or may be a graded refractive index type lens.
  • the first excitation light pulse arriving in the ignitor laser 50 causes ignitor laser
  • the second excitation light pulse arriving in the ignitor laser causes output of a long duration low peak power pulse from the ignitor laser 50.
  • the alternating sequence of laser light output of the ignitor laser 50 is then focused
  • the lasers can be arranged as
  • high reflection end mirror 114 which is highly reflective of 808 nm wavelength light, a
  • Pockels cell 116 a polarization analyzer 1T8, a reflecting mirror 120, two output couplers 122
  • the excitation laser 110 is pumped by either flashlamps or light emitting diodes.
  • excitation laser 110 is operated at a wavelength of 808 nanometers to produce laser light
  • excitation laser 110 is in the range from about 200 ns to about 300 microseconds.
  • first output coupler 122 by not activating the Pockels cell 116 and allowing the light to pass
  • 400-micron diameter multiple-mode optical fiber is used for all
  • optical fibers are optical fibers.
  • the second focusing lens 128 focuses the second light pulse into the second optical fiber
  • reflecting mirror 136 are used to collimate and direct the second light pulse to the beam
  • the pulse width of the second excitation laser pulse is typically from about 50 to about
  • a Nd: YAG laser 150 having an input focusing lens 140, neodymium-doped YAG
  • Example I is used as the ignitor laser.
  • the first pulse of light from the excitation laser U0 is transported through the second
  • the ignitor laser output had a duration about 10 to 30 nanoseconds and a
  • excitation laser 110 are directed into a short focal length lens 146 and focused through a laser
  • a spark breakdown plasma in the fuel spray 154 is formed by the output of the ignitor
  • the excitation laser is operated to produce two sequential low peak power pulses having two different wavelengths.
  • Wavelengths of 808 nanometers and 850 nanometers were selected because the
  • Nd:YAG rod of the ignitor laser will absorb the 808 nm wavelength and will not absorb the
  • an output coupler 212 is positioned in the excitation laser 210 for this embodiment.
  • a Pockels cell 218 is positioned
  • the excitation laser 210 contains two end mirrors 222, 224 that are dielectric coated so
  • End mirror 222 is coated for high reflectivity at 808 nanometers; end mirror 224 is coated for high
  • the mirror reflecting light employed at any given time is determined by the voltage
  • coupler 212 is a broad-band reflector with a reflectivity in the range from about 30% to about
  • a brewster plate 226, birefringement filter, or other wavelength tuning element can be
  • the excitation laser 210 outputs a first pulse with a duration of about 50
  • power for the first excitation laser pulse is from about 1 kW to about 1 MW.
  • ignitor laser 230 has Q-switched, voltage is quickly applied to the Pockels cell 218.
  • this voltage generally is equal to the voltage of the Pockels cell 218, i.e., a halfwave voltage of about 3,500 V.
  • a halfwave voltage of about 3,500 V.
  • the polarization of the light is changed by 90°.
  • the polarization analyzer 220 will direct
  • Typical peak power for the second excitation laser pulse is from about 100
  • the light pulses from the excitation light source laser 210 are focused through a short
  • focal length lens 214 into a single multiple-mode optical fiber 228 a core diameter of about
  • the multiple-mode optical fiber 228 transports both excitation laser light pulses sequentially to the ignitor laser 230.
  • the configuration of the ignitor laser 230 is the same as that described in Example I.
  • Light from the optical fiber 228 is focused into the ignitor laser 230 through a lens 232 into
  • the first 808 nm wavelength pulse from the excitation light laser 210 is absorbed by
  • the ignitor laser rod 234 and energizes the ignitor laser 230, thereby producing a short
  • the short duration high peak power pulse from the ignitor laser 230 is focused through a focusing lens 238, then through a laser window 240
  • a breakdown plasma is produced at the focal point 242 by the first 808
  • the interval between the end of the first pulse and the start of the second pulse is
  • the second 850 nm wavelength pulse from the excitation light laser 210 is similarly transported to the ignitor laser 230.
  • the collimated light of the second pulse of light is not within the absorption band of either the laser rod 234 or Q-switch 236, the collimated light of the second
  • the lens 238 focuses
  • This second long duration low peak power pulse sustains the ignition of
  • FIG. 6 As depicted in Figure 6, a single
  • excitation light source laser 10 is used to provide low peak power long duration light pulse
  • the excitation laser light 12 is directed into a
  • the laser light is transported by each of the pairs of optical fibers to an ignitor laser
  • excitation light 12 is directed into the lower (bottom) face
  • exiting the prism 18 is then directed to a beam splitter 20a where the excitation laser light is
  • optical fibers 36a and 36a are optical fibers 36a and 36b.
  • excitation light in sequential pulses to an ignitor laser.
  • third, fourth, and more ignitor lasers can be powered by the single excitation
  • ignitor lasers can be energized sequentially by a single excitation light source.
  • a multiplexing device is
  • the small physical size and simplicity of design of the ignitor laser enables an effective, compact, robust and cost effective laser ignitor
  • the laser ignition hardware of this invention is suitable for use in harsh aerospace operating environments because it is compact, insensitive to engine
  • excitation sources are located at the excitation light source, which can be located within the
  • the ignition equipment at the engine reduces cooling requirements and reduces sensitivity to both vibrations and temperature.
  • the single excitation light source which can be placed in an easily accessable location. Since
  • the excitation light source is located remotely from the ignition site, its environment can be
  • the apparatus and method of the invention can be used as an ignition source for
  • turbojet engines internal combustion engines, diesel engines and gas turbines for electrical

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Electromagnetism (AREA)
  • Plasma & Fusion (AREA)
  • Lasers (AREA)

Abstract

Selon la présente invention, une source lumineuse d'excitation (10) et un allumeur laser (50) montés en tandem constituent un système d'allumage du carburant compact, à longue durée de vie, et adaptable à un moteur. Une unique source de lumière d'excitation située à distance suffit pour un ou plusieurs petits lasers situés à proximité d'une ou de plusieurs zones de combustion. Selon deux modes de réalisation, le faisceau de la source de lumière d'excitation est divisé. Une première partie aboutit à l'allumeur laser. Une seconde partie se combine soit à la première partie avant injection dans l'allumeur laser, soit à la sortie de l'allumeur laser. Selon un autre mode de réalisation, des impulsions brèves et longues provenant de la source de lumière d'excitation sont envoyées dans l'allumeur laser. Selon un autre mode de réalisation, la source de lumière d'excitation est un laser à plusieurs cavités de résonance. Selon un autre mode de réalisation, la source de lumière d'excitation est capable de produire des faisceaux alternatifs de lumière de différentes longueurs d'ondes pour le pompage. Chacune de ces réalisations se prête au multiplexage.
PCT/US2000/006255 2000-03-10 2000-03-10 Allumage laser WO2001069136A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU2000235236A AU2000235236A1 (en) 2000-03-10 2000-03-10 Laser ignition
PCT/US2000/006255 WO2001069136A1 (fr) 2000-03-10 2000-03-10 Allumage laser

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US2000/006255 WO2001069136A1 (fr) 2000-03-10 2000-03-10 Allumage laser

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WO2001069136A1 true WO2001069136A1 (fr) 2001-09-20

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Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004104492A2 (fr) * 2003-05-21 2004-12-02 Alexza Pharmaceuticals, Inc. Unite de chauffage autonome a allumage optique ou electrique, et unite d'administration de medicament utilisant cette unite de chauffage
WO2007056999A2 (fr) * 2005-11-17 2007-05-24 Technische Universität Berlin Systeme de laser a corps solide et procede permettant son fonctionnement
FR2894620A1 (fr) * 2005-12-14 2007-06-15 Ecet Europ De Conception Et D Systeme d'allumage laser
FR2894619A1 (fr) * 2005-12-14 2007-06-15 Ecet Europ De Conception Et D Systeme d'allumage laser
WO2008000585A1 (fr) * 2006-06-29 2008-01-03 Robert Bosch Gmbh Procédé pour faire fonctionner un dispositif d'allumage et dispositif d'allumage
US7618254B2 (en) * 2006-02-02 2009-11-17 Aga Ab Method for igniting a burner
WO2010072520A1 (fr) * 2008-12-16 2010-07-01 Robert Bosch Gmbh Bougie d'allumage à dispositif laser dans une chambre de précombustion
EP2770183A1 (fr) * 2013-02-22 2014-08-27 Pratt & Whitney Canada Corp. Allumage laser à focalisation variable de turbine à gaz
US9211382B2 (en) 2001-05-24 2015-12-15 Alexza Pharmaceuticals, Inc. Drug condensation aerosols and kits
US9441546B2 (en) 2013-02-26 2016-09-13 Pratt & Whitney Canada Corp. Laser-ignition combustor for gas turbine engine
US10006895B2 (en) 2012-09-20 2018-06-26 C.R.D. Centro Ricerche Ducati Trento S.R.L. System and method for monitoring atmospheric pollution
EP3951158A4 (fr) * 2019-03-28 2023-01-04 IHI Corporation Dispositif d'allumage par laser, moteur spatiale, et moteur d'aéronef
US11642473B2 (en) 2007-03-09 2023-05-09 Alexza Pharmaceuticals, Inc. Heating unit for use in a drug delivery device

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US4665529A (en) * 1986-05-19 1987-05-12 Spectra-Physics, Inc. Laser diode pumped solid state laser with miniaturized quick disconnect laser head
US5568503A (en) * 1993-10-08 1996-10-22 Terumo Kabushiki Kaisha Solid-state laser device with optical fiber cable connection
US5756924A (en) * 1995-09-28 1998-05-26 The Regents Of The University Of California Multiple laser pulse ignition method and apparatus

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US4665529A (en) * 1986-05-19 1987-05-12 Spectra-Physics, Inc. Laser diode pumped solid state laser with miniaturized quick disconnect laser head
US5568503A (en) * 1993-10-08 1996-10-22 Terumo Kabushiki Kaisha Solid-state laser device with optical fiber cable connection
US5756924A (en) * 1995-09-28 1998-05-26 The Regents Of The University Of California Multiple laser pulse ignition method and apparatus

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10350157B2 (en) 2001-05-24 2019-07-16 Alexza Pharmaceuticals, Inc. Drug condensation aerosols and kits
US9440034B2 (en) 2001-05-24 2016-09-13 Alexza Pharmaceuticals, Inc. Drug condensation aerosols and kits
US9211382B2 (en) 2001-05-24 2015-12-15 Alexza Pharmaceuticals, Inc. Drug condensation aerosols and kits
US8991387B2 (en) 2003-05-21 2015-03-31 Alexza Pharmaceuticals, Inc. Self-contained heating unit and drug-supply unit employing same
WO2004104492A3 (fr) * 2003-05-21 2005-01-27 Alexza Molecular Delivery Corp Unite de chauffage autonome a allumage optique ou electrique, et unite d'administration de medicament utilisant cette unite de chauffage
WO2004104492A2 (fr) * 2003-05-21 2004-12-02 Alexza Pharmaceuticals, Inc. Unite de chauffage autonome a allumage optique ou electrique, et unite d'administration de medicament utilisant cette unite de chauffage
US9370629B2 (en) 2003-05-21 2016-06-21 Alexza Pharmaceuticals, Inc. Self-contained heating unit and drug-supply unit employing same
WO2007056999A2 (fr) * 2005-11-17 2007-05-24 Technische Universität Berlin Systeme de laser a corps solide et procede permettant son fonctionnement
WO2007056999A3 (fr) * 2005-11-17 2008-10-23 Univ Berlin Tech Systeme de laser a corps solide et procede permettant son fonctionnement
EP1798397A1 (fr) * 2005-12-14 2007-06-20 Vibro Meter France Système d'allumage laser
FR2894619A1 (fr) * 2005-12-14 2007-06-15 Ecet Europ De Conception Et D Systeme d'allumage laser
FR2894620A1 (fr) * 2005-12-14 2007-06-15 Ecet Europ De Conception Et D Systeme d'allumage laser
US7618254B2 (en) * 2006-02-02 2009-11-17 Aga Ab Method for igniting a burner
JP2009541649A (ja) * 2006-06-29 2009-11-26 ローベルト ボツシユ ゲゼルシヤフト ミツト ベシユレンクテル ハフツング 点火装置の作動方法および点火装置
WO2008000585A1 (fr) * 2006-06-29 2008-01-03 Robert Bosch Gmbh Procédé pour faire fonctionner un dispositif d'allumage et dispositif d'allumage
US11642473B2 (en) 2007-03-09 2023-05-09 Alexza Pharmaceuticals, Inc. Heating unit for use in a drug delivery device
WO2010072520A1 (fr) * 2008-12-16 2010-07-01 Robert Bosch Gmbh Bougie d'allumage à dispositif laser dans une chambre de précombustion
US10006895B2 (en) 2012-09-20 2018-06-26 C.R.D. Centro Ricerche Ducati Trento S.R.L. System and method for monitoring atmospheric pollution
EP2770183A1 (fr) * 2013-02-22 2014-08-27 Pratt & Whitney Canada Corp. Allumage laser à focalisation variable de turbine à gaz
US9441546B2 (en) 2013-02-26 2016-09-13 Pratt & Whitney Canada Corp. Laser-ignition combustor for gas turbine engine
EP3951158A4 (fr) * 2019-03-28 2023-01-04 IHI Corporation Dispositif d'allumage par laser, moteur spatiale, et moteur d'aéronef

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