From the optical diffractive limit and the theoretical limit of information theory, it is easy to understand that the capacity of high-density digital holographic storage system is limited not only by the methods used for the optical settings, but also
by the limitations of the materials:— the former is limited to V/λ3 and the latter is limited to the material’s space bandwidth product (SBP), where V is the storage volume, λ is a record wavelength.