Wavelength beam combining laser systems utilizing lens roll for chief ray focusing
In various embodiments, a wavelength beam combining laser system includes a fast-axis collimation lens that is rotated with respect to a plurality of emitters in order to converge the emitted beams onto a dispersive element and/or reduce the size of the multi-wavelength output beam of the system.
1. A method of laser emission, the method comprising:
emitting individual beams from each of a plurality of beam emitters, each beam having a first axis and a second axis;
at least partially converging the beams toward a dispersive element with a collimation lens configured to collimate the beams along the first axis;
dispersing the beams with the dispersive element; and
receiving the dispersed beams, reflecting a first portion of the dispersed beams back to the dispersive element and thence to the plurality of beam emitters to stabilize emission wavelengths thereof, and transmitting a second portion of the dispersed beams as a multi-wavelength output beam.
2. The method of claim 1 , wherein the collimation lens at least partially converges the beams toward the dispersive element as a result of an orientation of an optical axis of the collimation lens.
3. The method of claim 2 , wherein the optical axis of the collimation lens is not aligned with the first or second axes of the beams.
4. The method of claim 1 , wherein the collimation lens causes the beams to at least partially overlap at the dispersive element.
5. The method of claim 1 , wherein an orientation of an optical axis of the collimation lens is insufficient to partially overlap the beams at the dispersive element.
6. The method of claim 5 , further comprising causing the converging beams to at least partially overlap at the dispersive element with one or more focusing optics.
7. The method of claim 6 , wherein the focusing optics are disposed at an optical distance away from the dispersive element that is less than a focal length of the focusing optics.
8. The method of claim 6 , wherein the focusing optics are disposed at an optical distance away from the beam emitters that is less than a focal length of the focusing optics.
9. The method of claim 1 , further comprising rotating the beams before dispersing the beams with the dispersive element.
10. The method of claim 9 , wherein the beams are rotated by approximately 90°.
11. The method of claim 9 , wherein the beams are rotated by a beam rotator.
12. The method of claim 11 , wherein the beam rotator is separate and discrete from the collimation lens.
13. The method of claim 11 , wherein the beam rotator and the collimation lens are portions of a single optical element.
14. The method of claim 11 , wherein the beam rotator comprises two spaced-apart cylindrical lenses.
15. The method of claim 11 , wherein an optical axis of the beam rotator is aligned with an optical axis of the collimation lens.
16. The method of claim 11 , wherein an optical axis of the beam rotator is not aligned with an optical axis of the collimation lens.
17. The method of claim 1 , wherein the collimation lens comprises a fast-axis collimation lens.
18. The method of claim 1 , wherein the dispersive element comprises a diffraction grating.
19. The method of claim 1 , further comprising coupling the output beam into an optical fiber.
20. The method of claim 1 , further comprising processing a workpiece with the output beam.
21. The method of claim 20 , wherein processing the workpiece comprises at least one of welding, cutting, or drilling the workpiece.