Single-step copying technique for multiplexed volume holograms

Abstract

A novel technique for copying the index or absorption modulation of a multiplexed volume hologram (MVH) into a second volume holographic medium in a single-step exposure is presented. The technique assumes that the master MVH is angularly multiplexed, and the individual holograms are independent in that each reference beam can recall only the corresponding object beam. Independence of the individual holograms is preserved in the copy. The copying technique utilizes a set of coherent sources (one for each individual hologram) that are mutually incoherent; each source provides two reference beams, one for an individual hologram in the master MVH and one for the corresponding hologram in the copy. When all sources are activated, the set of holograms in the master MVH are recalled and are mutually incoherent. The set of object beam wavefronts are imaged in amplitude and phase onto the secondary medium, and interfere with the corresponding reference beams, pairwise. Mutual incoherence prevents the recording of crosstalk gratings between the holograms in the copy.