Various effects associated with using a random phase mask in holographic
data storage are analyzed. It is shown that the nonlinear nature of recording
a phase hologram coupled with the highly nonuniform profile of the object beam
is the major source of interpixel cross talk. It is also shown that, although
the nonlinear effects are reduced by an increase in the reference-to-object
beam ratio, the scattering noise is increased. Thus an optimal beam ratio must
be used to maximize the signal-to-noise ratio. It is demonstrated as well that
the interpixel interference noise can be suppressed effectively by use of a
multilevel pseudorandom phase mask, which also significantly reduces the
nonlinear noise. These findings are supported by experimental results that
show the signal-to-noise ratio and efficiency are improved significantly by
use of a six-level pseudorandom phase mask.
© 1997 Optical Society of America
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