Despeckling stability
An apparatus and method that improves the stability of despeckling using stimulated Raman scattering in an optical fiber. Optical modes in the fiber are scrambled by physical movement of the optical fiber, focusing assembly, or laser beam. The improvement in stability may include a reduction in flicker or reduction in long-term drift.
1. A method of despeckling comprising:
generating a laser beam;
using a coupling assembly to focus the laser beam into an optical fiber;
generating stimulated Raman scattering light in the optical fiber;
scrambling a fiber mode in the optical fiber; and
using a statistical averaging of a power of a component mode to make an improvement in a stability of the stimulated Raman scattering light.
2. The method of claim 1 further comprising: using the stimulated Raman scattering light to form a projected digital image.
3. The method of claim 1 wherein the scrambling comprises a mechanical movement.
4. The method of claim 3 wherein the mechanical movement comprises a non-periodic movement.
5. The method of claim 3 wherein the mechanical movement comprises moving the optical fiber.
6. The method of claim 3 wherein the mechanical movement comprises moving the coupling assembly.
7. The method of claim 3 wherein the mechanical movement comprises moving the laser beam.
8. The method of claim 1 wherein the improvement in the stability comprises a reduction in a flicker.
9. The method of claim 1 wherein the improvement in the stability comprises a reduction in a drift.
10. An optical apparatus comprising:
a laser that generates a laser beam; an optical fiber;
a coupling assembly that focuses the laser beam into the optical fiber; and
a scrambling device that scrambles an optical mode in the optical fiber;
wherein a stimulated Raman scattering light from the optical fiber enhances an aspect of a light output of the optical fiber; and the scrambling device makes an improvement in a stability of the stimulated Raman scattering light.
11. The apparatus of claim 10 wherein the stimulated Raman scattering light forms a projected digital image.
12. The apparatus of claim 10 wherein the aspect of the light output of the optical fiber is a color of the output of the optical fiber.
13. The apparatus of claim 10 wherein the aspect of the light output of the optical fiber is a speckle characteristic of the output of the optical fiber.
14. The apparatus of claim 10 wherein the scrambling device comprises an electromagnetic motor.
15. The apparatus of claim 10 wherein the scrambling device comprises a piezoelectric element.
16. The apparatus of claim 10 wherein the scrambling device operates with a non-periodic motion.
17. The apparatus of claim 10 wherein the scrambler moves the optical fiber.
18. The apparatus of claim 10 wherein the scrambler moves the coupling assembly.
19. The apparatus of claim 10 wherein the scrambler moves the laser beam.
20. The apparatus of claim 10 wherein the improvement in the stability comprises a reduction in a flicker.
21. The apparatus of claim 10 wherein the improvement in the stability comprises a reduction in a drift.
22. The apparatus of claim 10 wherein the scrambler affects a temporal contrast of the light output from the optical fiber by less than 1%.