Buckling mode actuation of fiber scanner to increase field of view
Described herein are embodiments of fiber scanning systems and methods of scanning optical fibers. The disclosed systems and methods advantageously provide an improvement to the scanning range, the oscillation amplitude, and/or the maximum pointing angle for an optical fiber in a fiber scanning system by inducing a buckling of a portion of the optical fiber.
1. A system comprising:
an optical fiber having a distal fiber end and a proximal fiber end;
an electromechanical transducer mechanically coupled to the optical fiber between the distal fiber end and the proximal fiber end, wherein the electromechanical transducer is configured to:
apply a buckling force to the optical fiber by reducing a length of the electromechanical transducer between a distal transducer end of the electromechanical transducer and a proximal transducer end of the electromechanical transducer; and
excite whirling of the distal fiber end by laterally deflecting the distal transducer end of the electromechanical transducer.
2. The system of claim 1 , wherein the distal fiber end is unconstrained.
3. The system of claim 1 , wherein the buckling force periodically ramps in amplitude, wherein a lateral deflection amplitude for whirling of the optical fiber periodically ramps, and wherein ramping of the buckling force and ramping of the lateral deflection amplitude are synchronized.
4. The system of claim 1 , wherein a first joint mechanically coupling the electromechanical transducer and the optical fiber has a first axial stiffness along an axis parallel to a longitudinal axis of the optical fiber, wherein a second joint mechanically coupling the electromechanical transducer and the optical fiber has a second axial stiffness along the axis parallel to the longitudinal axis of the optical fiber, and wherein the first axial stiffness and the second axial stiffness are sufficient to induce buckling of the optical fiber when a distance between the first joint and the second joint is reduced by a distance between 0.1 μm and 5 μm.
5. The system of claim 4 , wherein the first joint has a lateral stiffness that is sufficient to accommodate lateral rotation of the optical fiber during buckling.
6. The system of claim 1 , wherein the electromechanical transducer corresponds to a piezo tube having the distal transducer end and the proximal transducer end, and wherein the optical fiber is mechanically coupled to both the distal transducer end and the proximal transducer end of the piezo tube.
7. The system of claim 6 , wherein the optical fiber passes through the piezo tube.
8. The system of claim 6 , wherein the buckling force is applied to the optical fiber by reducing a length of the piezo tube between the distal transducer end and the proximal transducer end.
9. The system of claim 6 , wherein the distal fiber end extends beyond the distal transducer end, and wherein the distal transducer end is positioned between the distal fiber end and the proximal transducer end.
10. The system of claim 6 , wherein the piezo tube has an inner diameter sufficient to accommodate buckling of the optical fiber.
11. The system of claim 6 , wherein the buckling piezo includes a plurality of electrodes for controlling a length of the piezo tube and for controlling lateral deflections of the distal transducer end by application of one or more voltages.
12. The system of claim 11 , wherein a buckling voltage simultaneously applied to the plurality of electrodes causes a length of the piezo tube along a longitudinal tube axis to change, and wherein different whirling voltages applied individually to the plurality of electrodes causes the distal transducer end to deflect laterally in a spiral configuration.
13. The system of claim 1 , wherein the electromechanical transducer includes a hub, a frame surrounding the hub, and a plurality of lateral electromechanical transducers mechanically coupled to the frame and to the hub, wherein the optical fiber passes through the hub, and wherein the hub is mechanically coupled to the optical fiber by a whirling joint.
14. The system of claim 13 , wherein the electromechanical transducer further includes a plurality of flexures extending radially from the hub and coupling the hub to the frame.
15. The system of claim 13 , wherein the lateral electromechanical transducers correspond to piezo elements including electrodes for controlling lateral deflections of the hub to excite whirling of the distal fiber end.
16. A method comprising:
applying a first voltage to an optical fiber scanning system to induce whirling of an optical fiber, wherein the optical fiber scanning system includes:
the optical fiber, wherein the optical fiber has a distal fiber end and a proximal fiber end;
an electromechanical transducer mechanically coupled to the optical fiber between the distal fiber end and the proximal fiber end, wherein the electromechanical transducer is configured to:
apply a buckling force to the optical fiber by reducing a length of the electromechanical transducer between a distal transducer end of the electromechanical transducer and a proximal transducer end of the electromechanical transducer; and
excite whirling of the distal fiber end by laterally deflecting the distal transducer end of the electromechanical transducer; and
applying a second voltage to the optical fiber scanning system to induce buckling of the optical fiber.
17. The method of claim 16 , wherein the electromechanical transducer includes a plurality of electrodes, wherein applying the first voltage includes applying the first voltage to the plurality of electrodes to induce lateral deflection of the optical fiber for exciting whirling of the distal fiber end, and wherein applying the second voltage includes applying the second voltage to the plurality of electrodes to induce longitudinal application of the buckling force.
18. The method of claim 16 , wherein whirling of the optical fiber causes the distal fiber end to deflect a first predetermined amount and wherein buckling of the optical fiber causes deflection of the distal fiber end by a second predetermined amount that is superimposed on the first predetermined amount.
19. The method of claim 16 , wherein applying the second voltage includes applying the second voltage a predetermined amount of time after applying the first voltage.
20. The method of claim 16 , wherein the first voltage repeats at a first frequency of between about 10 kHz and about 80 kHz, and wherein the second voltage repeats at a second frequency of between about 15 Hz and about 300 Hz.