Double pass, common path method for arbitrary polarization control using a ferroelectric liquid crystal spatial light modulator.

We present a method for arbitrary control of the polarization of a light beam. Our method uses two holograms on a binary ferroelectric liquid crystal spatial light modulator (FLCSLM), and so has the potential to allow polarization state switching at kilohertz rates. Unlike previous methods that achieve polarization control using FLCSLMs, our method is common path and requires only the simplest optical components. For this reason, the method is very easy to setup, align, and maintain. In addition, it has the ability to modulate unpolarized input light. We demonstrate the formation of radially, azimuthally, and circularly polarized beams by imaging their focal spots formed at low numerical aperture.