Coded multiple exposure holograms

Experiments have been performed in which 1000 holograms have been superimposed one upon the other in the same area of photographic emulsion. Each hologram was formed with a uniquely coded reference beam allowing reconstruction of only one of the superimposed holograms while the unaddressed holograms contribute incoherent noise. Signal-to-noise ratios are calculated and measured as a function of the number of superimposed exposures. For the 1000-exposure hologram, the observed signal-to-noise ratio for any one of the individual holograms was 10 dB.