Aberration compensated diode-laser stack
Optical output beams from a vertical stack of diode-laser bars are focused by a simple focusing lens on an optical axis of the lens. The optical output beams from outlying diode-laser bars in the vertical stack are tilted with respect to the optical axis of the focusing lens such that optical output from the whole vertical stack is brought to a common focus location on the optical axis of the focusing lens.
1. Optical apparatus comprising:
a stacked plurality of diode-laser bars, each diode-laser bar having an optical output beam that is substantially collimated in a fast-axis direction of the diode-laser bar by a fast-axis collimating lens;
a single element focusing lens having an optical axis and spherical aberration, the focusing lens intercepting the substantially-collimated beams of all of the diode-laser bars, the stacked diode-laser bars and the focusing lens arranged to bring all of the substantially-collimated beams to focus on the optical axis; and
wherein the substantially-collimated beams of at least one of the diode-laser bars are tilted at angles with respect to the optical axis by displacing the corresponding fast-axis collimating lenses laterally with respect to the propagation direction of the diode-laser emitters of the corresponding diode-laser bars, the substantially-collimated beams being tilted between the fast-axis collimating lenses and the focusing lens, the tilt angles selected such that the single element focusing lens directs all of the focused beams converge to a common focus location on the optical axis.
2. The optical apparatus of claim 1 , wherein each optical output beam is substantially collimated in a slow-axis direction of the diode-laser bar by a slow-axis collimating lens.
3. The optical apparatus of claim 1 , wherein the substantially-collimated beams of at least two of the diode-laser bars are tilted at angles with respect to the optical axis.
4. The optical apparatus of claim 1 , wherein the substantially-collimated beams originating from the outermost diode-laser bars of the stack are tilted with respect to the optical axis.
5. The optical apparatus of claim 4 , wherein substantially-collimated beams originating from the next-outermost diode-laser bars of the stack are tilted with respect to the optical axis.
6. The optical apparatus of claim 1 , wherein the focusing lens is a plano-convex lens.
7. Optical apparatus comprising:
a stacked plurality of diode-laser bars, each diode-laser bar having an optical output beam that is substantially collimated in a fast-axis direction of the diode-laser bar by a fast-axis collimating lens;
a single element focusing lens having an optical axis and spherical aberration, the focusing lens intercepting the substantially-collimated beams of all of the diode-laser bars, the stacked diode-laser bars and the focusing lens arranged to bring all of the substantially-collimated beams to focus on the optical axis; and
wherein the substantially-collimated beams of at least two of the outermost diode-laser bars of the stack are tilted at angles with respect to the optical axis by tilting the corresponding diode-laser bars, the substantially-collimated beams being tilted between the fast-axis collimating lenses and the focusing lens, at least three other diode-laser bars near the center of the stack are aligned parallel to the optical axis, the tilt angles selected such that the single element focusing lens directs all of the focused beams converge to a common focus location on the optical axis.
8. The optical apparatus of claim 7 , wherein each optical output beam is substantially collimated in a slow-axis direction of the diode-laser bar by a slow-axis collimating lens.
9. The optical apparatus of claim 7 , wherein substantially-collimated beams originating from the next-outermost diode-laser bars of the stack are tilted with respect to the optical axis.
10. The optical apparatus of claim 7 , wherein the focusing lens is a plano-convex lens.