High-speed dynamic beam shaping
Optical apparatus ( 20 ) includes a laser ( 22 ), which is configured to emit a beam of coherent optical radiation at a specified wavelength along a beam axis. A deflector ( 24 ) is configured to intercept and selectably deflect the beam over a range of angles relative to the beam axis. A plurality of diffractive optical elements (DOEs— 32, 34, 36, 64, 66, 68 ) are positioned to receive the deflected beam at different, respective deflection angles within the range and to output respective diffracted beams. Beam-combining optics ( 42, 74 ) are configured to receive and deflect the diffracted beams from the DOEs so that all of the diffracted beams are directed along a common output axis toward a target ( 48 ).
1. An optical apparatus, comprising:
a laser, which is configured to emit a beam of coherent optical radiation at a specified wavelength along a beam axis;
a deflector, which is configured to intercept and selectably deflect the beam over a range of angles relative to the beam axis, wherein the deflector comprises an acousto-optic device and a drive circuit, and wherein the acousto-optic device in the deflector is a first acousto-optic deflector;
a plurality of diffractive optical elements (DOEs), which are positioned to receive the deflected beam at different, respective deflection angles within the range and to output respective diffracted beams, wherein the drive circuit is coupled to apply to the acousto-optic device a drive signal having a frequency that is selectable so as to cause the acousto-optic device to deflect the beam selectably toward each of the DOEs; and
beam-combining optics, which are configured to receive and deflect the diffracted beams from the DOEs so that all of the diffracted beams are directed along a common output axis toward a target, wherein the beam-combining optics comprise a second acousto-optic deflector, which is driven in synchronization with the first acousto-optic deflector to deflect the diffracted beams in a direction along the common output axis.
2. The apparatus according to claim 1 , wherein the plurality of DOEs comprise a single substrate having any array of different diffractive patterns disposed thereon so as to define the plurality of the DOEs.
3. The apparatus according to claim 1 , wherein the DOEs are configured to apply different, respective spatial intensity profiles to the respective diffracted beams.
4. The apparatus according to claim 1 , wherein the DOEs are configured to direct the respective diffracted beams at different, respective output angles so that the diffracted beams converge at the beam-combining optics.
5. The apparatus according to claim 1 , wherein the beam-combining optics comprise a DOE.
6. The apparatus according to claim 1 , wherein the acousto-optic device is configured to deflect the beam over a first range of angles, and wherein the deflector comprises beam-expanding optics, which are positioned between the acousto-optic device and the DOEs and are configured to expand the first range into a second range that encompasses the respective deflection angles of all the DOEs.
7. The apparatus according to claim 1 , wherein the second acousto-optic deflector is configured to scan the common output axis so that the diffracted beams impinge on multiple different points on the target.
8. The apparatus according to claim 1 , wherein the drive circuit is configured to apply the drive signal at two or more frequencies simultaneously, which causes the acousto-optic device to split the beam into two or more sub-beams at the respective deflection angles of two or more of the DOEs.
9. The apparatus according to claim 8 , wherein the beam-combining optics are configured to recombine the sub-beams to impinge together along the common output axis on the target after diffraction from the DOEs.
10. The apparatus according to claim 9 , wherein the drive circuit is configured to adjust a temporal intensity profile of the recombined sub-beams by varying a phase difference between the two or more frequencies.
11. The apparatus according to claim 9 , wherein the drive circuit is configured to adjust a temporal intensity profile of the recombined sub-beams by varying respective amplitudes of the two or more frequencies in the drive signal.
12. The apparatus according to claim 1 , wherein the drive circuit is configured to switch the frequency of the drive signal, so as to switch an angle of deflection of the beam among the DOEs, within a switching time that is less than 10 us.
13. An optical method, comprising:
directing a beam of coherent optical radiation at a specified wavelength along a beam axis;
selectably deflecting the beam over a range of angles relative to the beam axis so as to generate one or more deflected beams at different, respective deflection angles, which are selected within the range so that the one or more deflected beams impinge respectively on one or more diffractive optical elements (DOEs), among a plurality of DOEs, whereby the one or more DOEs output respective diffracted beams; and
deflecting the diffracted beams from the DOEs so that all of the diffracted beams are directed along a common output axis toward a target, wherein the beam is deflected by an acousto-optic device, and wherein selectively deflecting the beam comprises selecting a frequency of a drive signal that is applied to the acousto-optic device so as to cause the acousto-optic device to deflect the beam selectably toward each of the DOEs, wherein the acousto-optic device that selectively deflects the beam is a first acousto-optic deflector, and wherein deflecting the diffracted beams comprises driving a second acousto-optic deflector in synchronization with the first acousto-optic deflector to deflect the diffracted beams in a direction along the common output axis.
14. The method according to claim 13 , wherein the plurality of DOEs comprise a single substrate having any array of different diffractive patterns disposed thereon so as to define the plurality of the DOEs.
15. The method according to claim 13 , wherein the DOEs are configured to apply different, respective spatial intensity profiles to the respective diffracted beams.
16. The method according to claim 13 , wherein the DOEs are configured to direct the respective diffracted beams at different, respective output angles so that the diffracted beams converge at beam-combining optics, which deflect the diffracted beams from the DOEs along the common output axis toward the target.
17. The method according to claim 13 , wherein the diffracted beams are deflected along the common output axis by the DOEs.
18. The method according to claim 13 , wherein the acousto-optic device is configured to deflect the beam over a first range of angles, and wherein selectively deflecting the beam comprises positioning beam-expanding optics between the acousto-optic device and the DOEs so as to expand the first range into a second range that encompasses the respective deflection angles of all the DOEs.
19. The method according to claim 13 , wherein driving the second acousto-optic deflector comprises scanning the output axis so that the diffracted beams impinge on multiple different points on the target.
20. The method according to claim 13 , wherein selecting the frequency of the drive signal comprises applying the drive signal at two or more frequencies simultaneously, which causes the acousto-optic device to split the beam into two or more sub-beams at the respective deflection angles of two or more of the DOEs.
21. The method according to claim 20 , wherein deflecting the diffracted beam comprises recombining the sub-beams to impinge together along the common output axis on the target after diffraction from the DOEs.
22. The method according to claim 21 , wherein applying the drive signal comprises varying a phase difference between the two or more frequencies so as to adjust a temporal intensity profile of the recombined sub-beams.
23. The method according to claim 21 , wherein applying the drive signal comprises varying respective amplitudes of the two or more frequencies in the drive signal so as to adjust a temporal intensity profile of the recombined sub-beams.
24. The method according to claim 13 , wherein selecting the frequency comprises switching the frequency of the drive signal, so as to switch an angle of deflection of the beam among the DOEs, within a switching time that is less than 10 μs.
25. An optical apparatus, comprising:
a laser, which is configured to emit a beam of coherent optical radiation at a specified wavelength along a beam axis;
an acousto-optic device, which is configured to intercept and selectably deflect the beam over a range of angles relative to the beam axis, wherein the acousto-optic device is a first acousto-optic deflector;
a drive circuit, which is coupled to apply to the acousto-optic device a drive signal at two or more frequencies simultaneously, so as to cause the acousto-optic device to split the beam into two or more sub-beams at different, respective deflection angles and to deflect the beam selectably toward each of a plurality of deflecting elements;
a plurality of deflecting elements, which are positioned to receive the sub-beams at the different, respective deflection angles within the range and to direct the sub-beams toward a common intersection point; and
beam-combining optics, which are configured to receive the sub-beams at the common intersection point from the deflecting elements and to recombine the sub-beams into an output beam, which impinges along a common output axis on a target, wherein the beam-combining optics comprise a second acousto-optic deflector, which is driven in synchronization with the first acousto-optic deflector to deflect the sub-beams in a direction along the common output axis.
26. The apparatus according to claim 25 , wherein the drive circuit is configured to adjust a temporal intensity profile of the recombined sub-beams by varying a phase difference between the two or more frequencies.
27. The apparatus according to claim 25 , wherein the drive circuit is configured to adjust a temporal intensity profile of the recombined sub-beams by varying respective amplitudes of the two or more frequencies in the drive signal.
28. The apparatus according to claim 25 , wherein the drive circuit is configured to adjust a temporal intensity profile of the recombined sub-beams by switching the frequencies of the drive signal, so as to switch the deflection angles of the sub-beams.
29. The apparatus according to claim 25 , wherein the deflecting elements comprise diffractive optical elements (DOEs).