Abstract: A method of preparing a copy hologram from a master hologram in which the light employed in the copying process is modified by passing an exposing beam through a light modulating array. At least some members of the array have modified light transmissivities in accordance with information derived from a reconstruction of the master hologram.

Abstract: Reflection holograms are described and are prepared from a transmission hologram. The reflection hologram is divided into a plurality of sequential parallel notional strips each of which is divided into bands, the bands and strips extending across the hologram from one side or end to the other and being parallel. Each band of a strip contains information derived from a respective notional strip into which the transmission hologram was divided during production of the reflection hologram. Thus each strip of the reflection hologram contains information derived from the whole of the transmission hologram. The reflection hologram is produced from the transmission hologram by a process in which each band of a notional strip of the reflection hologram is exposed in turn to a respective notional strip of the transmission hologram.