The Radial Polarization converter (RPC)from ARCoptix is a worldwide
unique device that converts a conventional linearly polarized beam into
a beam that has a CONTINUOUS
radial or azimuthal Polarization distribution and stable in time. As
illustrated in the figure below the orientation of the Polarization
vector varies spatially but
locally the Polarization state is considered as linear.
Thanks to the special alignment of the liquid crystal molecules,
the Polarization converter rotates locally the orientation of the
linearly polarized beam. Depending
of the settings of the device, we may obtain either azimuthally or a
radially polarization distribution at the output as described in the
figure above.
The RPC can be ordered in different options (with phase compensator and TN cell) depending of your application..
Generation of Laguerre-Gaussian beam (LG beam or doughnut beam)
With the help of the Arcoptix RPC, LG beams and also Bessel-Gauss
beam can relatively easily be generated from any laser in the VIS-NIR
region
(including also pulsed lasers)
By simply focalizing (here NA 0.9) an azimuthal collimated laser
beam that has passed through the Polarization converter, we obtain a
typically doughnut beam as shown on
the left figure here below. With the help of a linear polarizer
parallel to X and Y axis, we obtain respectively the the two-half-lobes
spots corresponding to x-y Polarization
components of the same doughnut beam (figures in the center).
By inserting an additional annular slit in the setup, we obtain
focused annular azimuthal beam (here with a NA 0.9 objective) generating
so a 1st order Bessel-Gauss beam
or also called vortex beams (figure on the right).