Set #1
Set #2
Pictures taken on August 10, 2010
| A vortex beam from a single lens mode converter is focused by a lens placed about a meter away (in the far field). The lens replicates the pattern of waists around the cylinder lens within the converter. A second lens with a short focal length (25.4mm) is used to magnify the beam at the replicated waist. Near this waist, the beam is elliptical because one beam component is focused before the other. At the midpoint of the two waists where the beams cross, the Gouy phase shift gained at the cylindrical lens is undone, so the beam is restored to a Hermite Gaussian form at this point. |
Set #3
Pictures taken on August 14, 2010
| By tilting the refocusing lens by merely 8.1 degrees, the waists were brought together to a single point. We used Coddington's equation to find the new focal lengths in the x and y directions. The new focal length in the y direction (the axis influenced by the cylinder lens) is 252.46, and 247.57 for the x axis. |