Some parameters related to the photographic recording of digital data by means of superposed diffraction gratings have been studied. The efficiencies of composite patterns formed by coherent multiple-beam interference depend strongly on the average exposure, beam balance ratios, spatial frequencies employed, and whether the exposures are made simultaneously or sequentially. Simultaneous exposures of N recording beams yield first-order outputs that are more intense by the factor N than the outputs of the same number of sequential exposures, other conditions being equal. The usable readout signal strength is limited primarily by the appearance of false images caused by nonlinear film transfer characteristics.
L. L Blackmer, A. P. VanKerkhove, R. E. Baldwin, and K. F. Stultz, "Some Aspects of Multiple-Beam Interference Techniques in Digital Data Recording," Appl. Opt. 9, 2753-2761 (1970)