Apparatus and method for fiber-laser output-beam shaping for spectral beam combination

• US 9,366,872 B2
• Filed: 02/18/2014
• Issued: 06/14/2016
• Est. Priority Date: 02/18/2014
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Honea, Eric C., Hu, Yongdan
• Primary Examiner(s): Martinez, Joseph P
• Application Number:
  US13/987,265
• Publication Number:
  US 20150234195A1
• Time in Patent Office: 847 Days
• US Class Current: 1/1
• CPC Class Codes: G02B 19/0023 at least one surface having optical power
• CPC Class Codes: G02B 19/0047 for use with a light source G02B19/009, G02B19/0095 take precedence; details of lighting devices in general F21V; non-semiconductor lasers having optical devices external to the laser cavity H01S3/005
• CPC Class Codes: G02B 27/0905 Dividing and/or superposing multiple light beams
• CPC Class Codes: G02B 27/0927 Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat
• CPC Class Codes: G02B 27/0944 Diffractive optical elements, e.g. gratings, holograms gratings per se G02B5/18; holograms used as optical elements per se G02B5/32
• CPC Class Codes: G02B 27/1006 for splitting or combining different wavelengths G02B27/1086, G02B27/141 take precedence
• CPC Class Codes: G02B 27/1086 operating by diffraction only
• CPC Class Codes: G02B 27/30 Collimators
• CPC Class Codes: G02B 5/001 Axicons, waxicons, reflaxicons
• CPC Class Codes: H01S 3/005 Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping shaping laser beam for working metal or other materials B23K26/06; optical elements, systems or apparatus in general G02B
• CPC Class Codes: H01S 3/067 Fibre lasers
• CPC Class Codes: H01S 3/2391 emitting at different wavelengths

Abstract

A method and apparatus for combining a plurality of laser beamlets to form a single annular beam using spectral beam combination. This invention includes a plurality of laser sources that emit a plurality of beamlets, wherein each one of the plurality of beamlets has a different wavelength; a beam annularizer that includes a plurality of optical units arranged to receive the beamlets, and configured to convert each beamlet into a respective annular beam that has an annular cross-sectional power profile; a beam-intersection transform element configured to point each respective one of the plurality of annular beams in an angular intersection arrangement toward a first location; and a spectral beam combiner at the first location configured to combine the plurality of wavelengths in the plurality of annular beams into a first annular spectrally combined beam.

Claims

1. A system for combining a plurality of laser beamlets to form a single annular beam using spectral beam combination, the system comprising:

a plurality of laser sources that emit a plurality of beamlets, wherein each one of the plurality of beamlets has a different wavelength;

a beam annularizer that includes a plurality of optical units arranged to receive the beamlets, and configured to convert each beamlet into a respective annular beam that has an annular cross-sectional power profile;

a beam-intersection transform element configured to point each respective one of the plurality of annular beams in an angular intersection arrangement toward a first location; and

a spectral beam combiner at the first location configured to combine the plurality of wavelengths in the plurality of annular beams into a first annular spectrally combined beam.

2. The system of claim 1, wherein the first annular combined beam is a collimated beam.

3. The system of claim 2, further comprising:

a Cassegrain projector operatively coupled to receive the first annular spectrally combined collimated beam and configured to form a second collimated annular output beam from the optical energy of the first annular combined collimated beam.

4. The system of claim 1, wherein the first annular spectrally combined beam is a diverging annular beam.

5. The system of claim 4, further comprising:

a Cassegrain projector operatively coupled to receive the first annular combined diverging beam and configured to form a second collimated annular output beam from the optical energy of the first annular combined diverging beam.

6. The system of claim 1, wherein the plurality of laser sources includes a plurality of optical-fiber lasers.

7. The system of claim 1, further comprising:

a mobile vehicle;

an electrical power supply mounted to the vehicle;

a laser controller mounted to the vehicle and operatively coupled to receive electrical power from the electrical power supply and operably coupled to power and control the plurality of laser sources;

a Cassegrain projector mounted to the vehicle and operatively coupled to receive the first annular spectrally combined beam and configured to form a collimated second annular output beam from the optical energy of the first annular spectrally combined beam; and

a beam-direction controller operably coupled to the Cassegrain projector and operable to direct the second annular output beam in one of a plurality of different possible directions relative to the vehicle.

8. The system of claim 1, wherein the first annular combined beam is a collimated beam, the system further comprising:

a Cassegrain projector operatively coupled to receive the first annular spectrally combined collimated beam and configured to form a second collimated annular output beam from the optical energy of the first annular combined collimated beam, wherein the second collimated annular output beam has a larger-diameter than the first annular spectrally combined collimated beam.

9. The system of claim 1, further comprising:

one or more optical elements; and

an active positioning control subsystem operably connected to the one or more of the optical elements to position the beams such that light from all the beams is aligned in the output beam.

10. A method for combining a plurality of laser beamlets to form a single annular beam using spectral beam combination, the method comprising:

emitting a plurality of laser beamlets from a plurality of laser sources, wherein each one of the plurality of beamlets has a different wavelength;

annularizing each of the plurality of beamlets to convert each beamlet into a respective annular beam each having an annular cross-sectional power profile;

pointing each respective one of the plurality of annular beams in a angularly intersecting direction toward a first location; and

spectral beam combining the intersecting beams at the first location to combine the light of the plurality of wavelengths in the plurality of annular beams into a first annular spectrally combined beam.

11. The method of claim 10, wherein the first annular combined beam is a collimated beam.

12. The method of claim 11, further comprising:

providing a Cassegrain projector; and

receiving the first annular combined collimated beam into the Cassegrain projector, and forming, with the Cassegrain projector, a second collimated annular output beam from the optical energy of the first annular combined collimated beam.

13. The method of claim 10, wherein the first annular spectrally combined beam is a diverging annular beam.

14. The method of claim 10, further comprising:

providing a mobile vehicle having an enclosure;

supplying electrical power from the vehicle;

using the electrical power to control and power the plurality of laser sources;

providing a Cassegrain projector mounted to the vehicle;

receiving the first annular spectrally combined beam into the Cassegrain projector, and forming, with the Cassegrain projector, a collimated second annular output beam from the optical energy of the first annular combined diverging beam; and

controlling an output direction of the second annular output beam in one of a plurality of different possible directions relative to the vehicle.

15. The method of claim 10, further comprising:

astigmatically reshaping the plurality of annular intersecting beams such that a height-to-width ratio of the first annular combined collimated beam is substantially one.

16. A method for combining a plurality of laser beamlets to form a single annular beam using spectral beam combination, the method comprising:

emitting a plurality of laser beamlets from a plurality of laser sources, wherein each one of the plurality of beamlets has a different wavelength;

annularizing each of the plurality of beamlets to convert each beamlet into a respective annular beam each having an annular cross-sectional power profile;

pointing each respective one of the plurality of annular beams in a angularly intersecting direction toward a first location;

spectral beam combining the intersecting beams at the first location to combine the light of the plurality of wavelengths in the plurality of annular beams into a first annular spectrally combined beam; and

actively positioning one or more optical elements to position the plurality of annular beams such that light from all the annular beams is aligned in the first annular combined collimated beam.

17. A system for combining a plurality of laser beamlets to form a single annular beam using spectral beam combination, the system comprising:

means for emitting a plurality of laser beamlets, wherein each one of the plurality of beamlets has a different wavelength;

means for annularizing each of the plurality of beamlets to convert each beamlet into a respective annular beam each having an annular cross-sectional power profile;

means for pointing each respective one of the plurality of annular beams in a angularly intersecting direction toward a first location; and

means for spectral beam combining the intersecting beams at the first location to combine the light of the plurality of wavelengths in the plurality of annular beams into a first annular spectrally combined beam.

18. The system of claim 17, further comprising:

means for astigmatically reshaping the plurality of annular intersecting beams such that a height-to-width ratio of the first annular combined collimated beam is substantially one.

19. The system of claim 17, wherein the first annular spectrally combined beam is a collimated beam.

20. The system of claim 19, further comprising:

a Cassegrain projector; and

means for receiving the first annular spectrally combined collimated beam into the Cassegrain projector, and forming, with the Cassegrain projector, a collimated second annular output beam from the optical energy of the first annular combined collimated beam.

21. The system of claim 17, wherein the first annular spectrally combined beam is a diverging annular beam.

22. The system of claim 21, further comprising:

a mobile vehicle having an enclosure;

means for supplying electrical power from the vehicle;

means for controlling and powering the means for emitting the plurality of laser beamlets;

a Cassegrain projector mounted to the vehicle;

means for receiving the first annular spectrally combined beam into the Cassegrain projector, and for forming, with the Cassegrain projector, a collimated second annular output beam from the optical energy of the first annular combined beam; and

means for controlling an output direction of the second annular output beam in one of a plurality of different possible directions relative to the vehicle.