Compact alpha-BBO acousto-optic deflector with high resolving power for UV and visible radiation

Patent metadata

Field	Value
Publication number	US-10996540-B2
Application number	US-201816160939-A
Country	US
Kind code	B2
Filing date	Oct 15, 2018
Priority date	Apr 26, 2018
Publication date	May 4, 2021
Grant date	May 4, 2021

Abstract

The technology disclosed relates to developing an acousto-optic device (AOD) using an alpha-barium borate (αBBO) crystal. An AOD using αBBO enables high-resolution microlithographic patterning. The AOD includes a slab of αBBO coupled to an RF transducer that drives an acoustic wave through the crystal structure. A laser source emits a beam of light that is incident on the crystal surface. The propagated acoustic wave acts as a diffraction grating that diffracts the incident wave. Using an αBBO crystal allows for high resolution of light in the ultraviolet and visible spectra. The low speed of acoustic wave propagation through the crystal allows for more laser spots to be imaged than AODs made using other types of crystals.

First claim

I claim as follows:

1. An acousto-optic device (AOD) component, comprising:
an alpha-barium borate (αBBO) crystal;
a coupling surface on the αBBO crystal;
active transducers on the coupling surface;
the active transducers coupled to a coherent driving source with an optional phase difference;
wherein, relative to an optic axis of the αBBO crystal, the active transducers and the coherent driving source are configured to launch an acoustical wavefront normal to a plane, wherein the plane is
rotated in a range of 10±0.2 degrees from the optic axis and
rotated counter-clockwise in a range of 63.5±1.0 degrees or in a range of 70±1.0 degrees from an a-axis of the αBBO crystal, or trigonal by 120 degrees from that rotation.

2. The AOD component of claim 1 , wherein:
the active transducers and the coherent driving source are configured to induce the acoustical wavefront with a divergent angular spread of 0.4 to 1.0 degrees.

3. The AOD component of claim 1 , wherein:
the active transducers and the coherent driving source are configured to induce the acoustical wavefront with a divergent angular spread of 0.5 to 0.7 degrees.

4. The AOD component of claim 1 , wherein:
a signal from the coherent driving source to the active transducers is centered at 450 MHz, ±50 MHz.

5. The AOD component of claim 1 , further comprising:
a signal from the coherent driving source to the active transducers has a frequency sweep of 300 MHz, ±50 MHz.

6. The AOD component of claim 1 , wherein:
the αBBO crystal includes an acoustical coupling surface that is parallel to a transducer plane that is
rotated in a range of 10±0.2 degrees from the optic axis and
rotated counter-clockwise in a range of 63.5±1.0 degrees or in a range of 70±1.0 degrees from the a-axis of the αBBO crystal, or trigonal by 120 degrees from that rotation.

7. The AOD component of claim 1 , further comprising:
an acoustical coupling surface, to which one or more transducers are coupled, that is coincident with the plane normal to the acoustical wavefront.

8. The AOD component of claim 1 , wherein:
the acoustical wavefront launch is further configured to produce an acoustic transmission speed in a direction of the launch of 1255±10 meters per second.

9. A method for producing an acousto-optic device (AOD) component, comprising:
relative to an optic axis of an alpha-barium borate (αBBO) crystal, creating an acoustical wavefront launch from a coupling surface and active transducers on the coupling surface that are driven by a coherent source with an optional phase difference,
wherein the acoustical wavefront is launched normal to a plane, wherein the plane is rotated in a range of 10±0.2 degrees from the optic axis and
rotated counter-clockwise in a range of 63.5±1.0 degrees or in a range of 70±1.0 degrees from an a-axis of the αBBO crystal, or trigonal by 120 degrees from that rotation.

10. The method of claim 9 , further wherein:
the acoustical wavefront has a divergent angular spread of 0.4 to 1.0 degrees.

11. The method of claim 9 , further wherein:
the acoustical wavefront has a divergent angular spread of 0.5 to 0.7 degrees.

12. The method of claim 9 , further comprising:
applying a signal to the active transducers centered at 450 MHz, ±50 MHz.

13. The method of claim 9 , further comprising:
applying a signal to the active transducers with a frequency sweep of 300 MHz, ±50 MHz.

14. The method of claim 9 , further comprising:
relative to the optic axis of an αBBO crystal, creating an acoustical coupling surface that is parallel to a transducer plane,
wherein the transducer plane is a plane that is
rotated in a range of 10±0.2 degrees from the optic axis and
rotated counter-clockwise in a range of 63.5±1.0 degrees or in a range of 70±1.0 degrees from the a-axis of the αBBO crystal, or trigonal by 120 degrees from that rotation.

15. The method of claim 9 , further comprising:
creating an acoustical coupling surface, to which one or more transducers are coupled, that is coincident with the plane normal to the acoustical wavefront.

16. The method of claim 9 , wherein:
the acoustical wavefront is launched at an angle that produces an acoustic transmission speed in a direction of the launch of 1255±10 meters per second.

17. An acousto-optic device (AOD) component, comprising:
an alpha-barium borate (αBBO) crystal;
a coupling surface on the αBBO crystal;
active transducers on the coupling surface;
the active transducers coupled to a coherent driving source with an optional phase difference;
wherein, relative to an optic axis of the αBBO crystal, the active transducers and the coherent driving source are configured to launch an acoustical wavefront normal to a plane, wherein the plane is
rotated in a range of 7.7±0.2 degrees from the optic axis and
rotated counter-clockwise in a range of 64.5±2.5 degrees from an a-axis of the αBBO crystal, or trigonal by 120 degrees from that rotation.

18. The AOD component of claim 17 , wherein:
the active transducers and the coherent driving source are configured to induce the acoustical wavefront with a divergent angular spread of 1.1 to 1.3 degrees.

19. The AOD component of claim 17 , wherein:
a signal from the coherent driving source to the active transducers is centered at 450 MHz, ±50 MHz.

20. The AOD component of claim 17 , wherein:
the αBBO crystal includes an acoustical coupling surface that is parallel to a transducer plane that is
rotated in a range of 7.7±0.2 degrees from the optic axis and
rotated counter-clockwise in a range of 64.5±2.5 degrees from the a-axis of the αBBO crystal, or trigonal by 120 degrees from that rotation.

21. The AOD component of claim 17 , wherein:
the acoustical wavefront launch is further configured to produce an acoustic transmission speed in a direction of the launch of 1220±7 meters per second.

22. An acousto-optic device (AOD) component, comprising:
an alpha-barium borate (αBBO) crystal;
a coupling surface on the αBBO crystal;
active transducers on the coupling surface;
the active transducers coupled to a coherent driving source with an optional phase difference;
wherein, relative to an optic axis of the αBBO crystal, the active transducers and the coherent driving source are configured to launch an acoustical wavefront normal to a plane, wherein the plane is
rotated in a range of 205±0.2 degrees from the optic axis and
rotated counter-clockwise in a range of 80±1.0 degrees from an a-axis of the αBBO crystal, or trigonal by 120 degrees from that rotation.

23. The AOD component of claim 22 , wherein:
the active transducers and the coherent driving source are configured to induce the acoustical wavefront with a divergent angular spread of 1.8 to 2.2 degrees.

24. The AOD component of claim 22 , wherein:
a signal from the coherent driving source to the active transducers is centered at 450 MHz, ±50 MHz.

25. The AOD component of claim 22 , wherein:
the αBBO crystal includes an acoustical coupling surface that is parallel to a transducer plane that is
rotated in a range of 205±0.2 degrees from the optic axis and
rotated counter-clockwise in a range of 80±1.0 degrees from the a-axis of the αBBO crystal, or trigonal by 120 degrees from that rotation.

26. The AOD component of claim 22 , wherein:
the acoustical wavefront launch is further configured to produce an acoustic transmission s

Assignees

• Mycronic AB

Inventors

• Ismail Nur

Classifications

• G02F1/332 Primary

  comprising a plurality of transducers on the same crystal surface, e.g. multi-channel Bragg cell · CPC title

• G02F1/33

  Acousto-optical deflection devices {(circuit or control arrangements therefor G02F1/113)} · CPC title

• G02F2203/22

  diffractive · CPC title

• G03F7/7015

  Details of optical elements · CPC title

• G02F1/292

  by controlled diffraction or phased-array beam steering (controlled diffraction for optical switching G02F1/31) · CPC title