The materials used to build our devices mix together solid-state media and soft matter. Photo-addressable substrates as photorefractive crystals, photoconductive plates or photovoltaic layers are associated with liquid crystals, polymers or membranes. The photo-addressable substrates realize the dynamical control of the reflective/refractive properties of the medium. This control is local, in the sense that the optical properties can be changed from point to point on the transverse spatial extension of the medium. Thanks to the photosensitive substrate, the addressing is made optically over a continuous surface, thus, removing the need for discrete pixels and largely simplifying the driving electronics.