US 6,676,402 B1Granted

Laser ignition

AssigneeThe Regents of the University of California

InventorsJames W. Early, Charles S. Lester

Life of this patent

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Abstract

Sequenced pulses of light from an excitation laser with at least two resonator cavities with separate output couplers are directed through a light modulator and a first polarzing analyzer. A portion of the light not rejected by the first polarizing analyzer is transported through a first optical fiber into a first ignitor laser rod in an ignitor laser. Another portion of the light is rejected by the first polarizing analyzer and directed through a halfwave plate into a second polarization analyzer. A first portion of the output of the second polarization analyzer passes through the second polarization analyzer to a second, oscillator, laser rod in the ignitor laser. A second portion of the output of the second polarization analyzer is redirected by the second polarization analyzer to a second optical fiber which delays the beam before the beam is combined with output of the first ignitor laser rod. Output of the second laser rod in the ignitor laser is directed into the first ignitor laser rod which was energized by light passing through the first polarizing analyzer. Combined output of the first ignitor laser rod and output of the second optical fiber is focused into a combustible fuel where the first short duration, high peak power pulse from the ignitor laser ignites the fuel and the second long duration, low peak power pulse directly from the excitation laser sustains the combustion.

Claims33

Dependent claims

An ignition apparatus comprising:

(a) an excitation light source;
(b) a light modulator positioned to receive output from said excitation light source;
(c) a first polarization analyzer positioned to receive light from said light modulator;
(d) a first output coupler positioned to receive a portion of light not redirected by said first polarization analyzer;
(e) a focusing lens positioned to inject said portion of light not redirected by said first polarization analyzer from said first output coupler into a first end of a first optical fiber;
(f) a second end of said first optical fiber connected to an ignitor laser so as to permit transport of said portion of light not redirected by said first polarization analyzer into a first lasing rod in said ignitor laser;
(g) a second output coupler positioned to receive a portion of light redirected by said first polarization analyzer;
(h) a halfwave plate positioned to receive from said second output coupler said portion of light redirected by said first polarization analyzer;
(i) a second polarization analyzer positioned to receive output from said halfwave plate;
(j) a second focusing lens positioned to inject light redirected by said second polarization analyzer into a first end of a second optical fiber;
(k) a second end of said second optical fiber connected to said ignitor laser so as to permit transport of said portion of light redirected by said first polarization analyzer into a beam combiner in said ignitor laser;
(l) a third focusing lens positioned to inject a portion of light not redirected by said second polarization analyzer into a first end of a third optical fiber;
(m) a second end of said third optical fiber connected to said ignitor laser so as to permit transport of said portion of light not redirected by said second polarization analyzer into a second lasing rod in said ignitor laser;
(n) an output coupler positioned to receive output from said second lasing rod in said ignitor laser;
(o) at least one turning prism to direct said output from said second lasing rod in said ignitor laser into said first lasing rod in said ignitor laser;
(p) said beam combiner also positioned to receive output from said first lasing rod in said ignitor laser;
and
(q) an ignitor output focusing lens positioned to direct output from said beam combiner into a combustible fuel.

15 more elements

An ignition method comprising:

(a) directing a beam from an excitation light source into a laser light modulator;
(b) applying a voltage to said laser light modulator intermittently in accordance with signals from a timing module, thereby controlling polarization of said laser light;
(c) directing said laser light from said laser light modulator into a first polarization analyzer which either rejects or transports said laser light according to whether or not said laser light has been polarized by said laser light modulator;
(d) directing any said laser light which is transported by said first polarization analyzer through a first focusing lens into a first optical fiber, and thence into a first laser rod in an ignitor laser;
(e) splitting beam of any said laser light rejected by said first polarization analyzer into a first portion and a second portion;
(f) directing said first portion of said laser light rejected by said first polarization analyzer through a second focusing lens into a second optical fiber and thence into a beam combiner;
(g) directing said second portion of said laser light rejected by said first polarization analyzer through a third focusing lens into a third optical fiber, and thence into a second laser rod in said ignitor laser;
(h) directing output of said second laser rod in said ignitor laser into said first leaser rod in said ignitor laser;
(i) combining output of said first laser rod in said ignitor laser in said beam combiner with any light rejected by said second polarization analyzer to form a combined beam;
(j) directing said combined beam through a focusing lens into a combustible fuel.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/927,862Filed 10 Aug 2001 · continuation in part
Priority: 21 Apr 1997
Granted: 13 Jan 2004
Term ends: Not estimatedThe source records don’t support an estimate.

Classification10 codes

F02P 23/04
Other ignition: other physical ignition means, e.g. using laser rays
H01S 3/0602
Construction or shape of active medium: crystal lasers or glass lasers
H01S 3/094038
By coherent light: end pumping
H01S 3/094053
Guiding of the pump light: fibre coupled pump, e.g. delivering pump light using a fibre or a fibre bundle

Family

Application60/044,483Us provisional application · filed 21 Apr 1997
Application08/861,214Parent of this continuation-in-part · filed 21 May 1997
Application09/267,122Parent of this continuation-in-part · filed 9 Mar 1999
US 6,394,788 B1Related patent
US 6,676,402 B1This patent

From the US filing history. Foreign family members aren’t listed.