Wavelength beam combining laser systems utilizing prisms for beam quality improvement and bandwidth reduction
In various embodiments, one or more prisms are utilized in a wavelength beam combining laser system to regulate beam size and/or to provide narrower wavelength bandwidth.
1. A wavelength beam combining laser system comprising:
one or more beam emitters configured to emit a plurality of discrete beams;
a dispersive element for receiving the beams and dispersing the beams;
disposed optically downstream of the beam emitters and optically upstream of the dispersive element, focusing optics for receiving the beams from the one or more beam emitters and focusing the beams such that chief rays of the emitters converge at the dispersive element;
a first prism positioned to receive the beams from the focusing optics, the first prism having (i) an entrance surface at which the beams are received and (ii) an exit surface, wherein (a) the first prism is spaced apart from both the focusing optics and the dispersive element, and (b) an angle of incidence of the beams at the entrance surface is larger than an exit angle of the beams at the exit surface, whereby the beams are expanded by the first prism; and
a partially reflective output coupler positioned to receive the dispersed beams, transmit a portion of the dispersed beams therethrough as a multi-wavelength output beam, and reflect a second portion of the dispersed beams back toward the dispersive element.
2. The laser system of claim 1 , wherein the dispersive element defines a dispersion plane.
3. The laser system of claim 2 , wherein the entrance surface of the first prism is not parallel to the dispersion plane.
4. The laser system of claim 2 , wherein the exit surface of the first prism is not parallel to the dispersion plane.
5. The laser system of claim 2 , wherein the beams have a focal plane, downstream of the first prism, that is substantially coplanar with the dispersion plane.
6. The laser system of claim 2 , further comprising, disposed optically downstream of the dispersive element and optically upstream of the output coupler, a second prism having an entrance surface and an exit surface.
7. The laser system of claim 6 , wherein the entrance surface of the second prism is not parallel to the dispersion plane.
8. The laser system of claim 6 , wherein the exit surface of the second prism is not parallel to the dispersion plane.
9. The laser system of claim 6 , wherein the beams are shrunk by the second prism.
10. The laser system of claim 1 , wherein the dispersive element comprises a diffraction grating.
11. The laser system of claim 1 , wherein the dispersive element is reflective.
12. The laser system of claim 1 , wherein the dispersive element is transmissive.
13. The laser system of claim 1 , further comprising an optical telescope disposed between the dispersive element and the output coupler.
14. The laser system of claim 13 , wherein the optical telescope comprises two cylindrical lenses.
15. The laser system of claim 1 , wherein an angle between the entrance surface of the first prism and the exit surface of the first prism ranges from approximately 10° to approximately 45°.
16. The laser system of claim 1 , wherein an angle between the entrance surface of the first prism and the exit surface of the first prism ranges from approximately 45° to approximately 75°.
17. The laser system of claim 1 , further comprising, disposed optically downstream of the first prism and optically upstream of the dispersive element, a second prism having an entrance surface and an exit surface, wherein the second prism is spaced apart from both the first prism and the dispersive element.
18. The laser system of claim 17 , wherein the entrance surface of the second prism is not parallel to the dispersion plane.
19. The laser system of claim 17 , wherein the exit surface of the second prism is not parallel to the dispersion plane.
20. The laser system of claim 17 , wherein the beams are shrunk by the second prism.