HIGH POWER LASER ASSEMBLY WITH ACCURATE POINTING IN THE FAR FIELD
A laser assembly ( 10 ) for generating an output beam ( 12 ) includes: (i) a first laser ( 16 ) that generates a first laser beam ( 16 A) having a first polarization state; (ii) a second laser ( 20 ) that generates a second laser beam ( 20 A); (iii) a polarization beam combiner ( 24 ) that combines the first laser beam ( 16 A) and the rotated second laser beam ( 20 A) to form a combination beam ( 25 ); and (iv) an optical assembly ( 32 ) that expands and collimates the combination beam ( 25 ) to provide the output beam ( 12 ). The optical assembly ( 32 ) include an on-axis telescope plus a projection lens.
1 . A laser assembly for generating an output beam, the laser assembly comprising:
a first laser that generates a first laser beam;
a second laser that generates a second laser beam;
a beam combiner that combines the first laser beam and the rotated second laser beam to form a combination beam; and
an optical assembly that expands and collimates the combination beam to provide the output beam that is accurately pointed in a far field, and pointing of the output beam is relatively insensitive to mechanical movement of the first laser, the second laser, and the beam combiner.
2 . The laser assembly of claim 1 wherein the first laser beam has a first polarization state; wherein the second laser generates the second laser beam having the first polarization state; and the laser assembly includes a polarization rotator that rotates the polarization of second laser beam to a second polarization state.
3 . The laser assembly of claim 1 wherein the first laser beam has a first polarization state; and wherein the second laser generates the second laser beam having a second polarization state that is different from the first polarization state.
4 . The laser assembly of claim 1 wherein each laser is a mid-infrared laser and a wavelength of each laser beam is in a mid-infrared range.
5 . The laser assembly of claim 4 wherein each mid-infrared laser is a tunable mid-infrared laser.
6 . The laser assembly of claim 1 wherein the combination beam is directed along a combination axis, and wherein the optical assembly includes a first lens, a second lens, and a third lens that are spaced apart from each other, wherein the lenses of the optical assembly are coaxial with the combination axis.
7 . The laser assembly of claim 6 wherein the first lens and the second lens form a beam expander that expands the combination beam, and the third lens is a projection lens that collimates the combination beam.
8 . The laser assembly of claim 7 wherein wherein the first lens is a convex element that focuses the combination beam, the second lens is a diverging element that diverges the combination beam, and the third lens is a collimating element that collimates the combination beam to launch the output beam into free space.
9 . The laser assembly of claim 7 wherein the optical assembly has a beam size magnification of at least one hundred.
10 . The laser assembly of claim 1 further comprising a first lens assembly that collimates the first laser beam directed at the polarization beam combiner, and a second lens assembly that collimates the second laser beam directed at the polarization beam combiner.
11 . A laser assembly for generating a mid-infrared output beam directed along an output axis, the laser assembly comprising:
a first laser that generates a first laser beam in a mid-infrared range having a first polarization state;
a first lens assembly that collimates the first laser beam;
a second laser that generates a second laser beam in the mid-infrared range;
a second lens assembly that collimates the second laser beam;
a polarization beam combiner that combines the collimated first laser beam and the collimated second laser beam to form a combination beam; and
an optical assembly that receives the combination beam and provides the mid-infrared output beam, the optical assembly including a first lens, a second lens, and a third lens that are spaced apart from each other; wherein the first lens is a convex element that focuses the combination beam, the second lens is a diverging element that diverges the combination beam, and the third lens is a collimating element that collimates the combination beam to launch the output beam into free space; wherein the lenses of the optical assembly are coaxial with, and spaced apart along, the output axis; wherein the first lens, the second lens and the third lens cooperate to minimize pointing errors of the output beam so that the output beam is accurately pointed in a far field.
12 . The laser assembly of claim 11 wherein the second laser generates the second laser beam having the first polarization state; and the laser assembly includes a polarization rotator that rotates the polarization of the collimated second laser beam to a second polarization state.
13 . The laser assembly of claim 11 wherein the second laser generates the second laser beam having a second polarization state that is different from the first polarization state.
14 . The laser assembly of claim 11 wherein the first lens and the second lens form a beam expander, and the third lens is a projection lens that collimates the combination beam.
15 . The laser assembly of claim 11 wherein the optical assembly has a beam size magnification of at least ten.
16 . The laser assembly of claim 11 wherein the optical assembly has a beam size magnification of at least one hundred.
17 . (canceled)
18 . (canceled)
19 . (canceled)
20 . (canceled)
21 . A method generating an output beam comprising:
generating a first laser beam;
collimating the first laser beam;
generating a second laser beam;
collimating the second laser beam;
combining the collimated first laser beam and the collimated second laser beam to form a combination beam; and
expanding and collimating the combination beam with an optical assembly to provide the output beam that is accurately pointed in a far field, and pointing of the output beam is relatively insensitive to temperature cycles and mechanical vibrations.
22 . The method of claim 21 wherein the step of expanding and collimating includes the optical assembly having a first lens, a second lens, and a third lens that are spaced apart from each other along a combination axis; wherein the lenses of the optical assembly are coaxial with the combination axis; and wherein the first lens and the second lens form a beam expander that expands the combination beam, and the third lens is a projection lens that collimates the combination beam.
23 . The method claim 22 wherein the step of expanding and collimating includes the first lens being a convex element that focuses the combination beam, the second lens being a diverging element that diverges the combination beam, and the third lens being a collimating element that collimates the combination beam to launch the output beam into free space along an output axis.
24 . (canceled)
25 . (canceled)
26 . (canceled)
27 . (canceled)
28 . (canceled)
29 . The method of claim 17 further comprising rotating the polarization of the collimated, second laser beam prior to the second laser beam being combined into the combination beam.