Pre-exposure and curing of photo-sensitive material for optical data storage

The present invention relates to an apparatus (1) for writing to optical storage media (10) capable of performing pre-exposure and/or curing of a photo-sensitive material for optical data storage, in particular for holographic data storage. The apparatus (1) has a first light source (2) for emitting a first light beam (7, 8), a second light source (14) for emitting a second light beam (15), and a spatial light modulator (6), which is switchable between at least two states for spatially modulating at least a part of the first light beam (7), and which is arranged such that in a first state it directs the first light beam (7, 8) towards an optical storage medium (10), and that in a second state it directs the second light beam (15) towards the optical storage medium (10).