Resolution limit of photorefractive spatial light modulators

The experimental set-up of our photorefractive incoherent to coherent converter 1 is shown in figure 1. With two interfering Ar-ion-laser beams (λ=514.5 nm) we write a phase hologram into a photorefractive KNbO3 crystal. Using anisotropic Bragg diffraction 2 we choose the direction of the diffracted beam (λ=632.8 nm) perpendicular to the crystal surface. The input image is projected into the crystal plate anti-parallel to the diffracted beam. A short wavelength transmitting dichroitic beam splitter is used to separate the incoherent light from the diffracted beam. This set-up shows highest resolution 3.