Abstract

By considering a single, diffraction limited spot as a single bit of information and taking into account that the diffraction limited spot in Fourier domain is equivalent to a plane wave, it has been shown that maximal bit capacity N of a hologram is proportional to its overall surface S (not to its volume) and is given by the formula N = S / [2π(κλ)²]. κ is a coefficient defining a required distance between spots (κ = 0.61 if the Rayleigh criterion for resolution of two spots is applied), λ is the wavelength of the light used, and S is the total surface of the hologram (both sides of flat element). For coherent imaging the coefficient k should be increased at least three times, resulting in a decrease of capacity by one order of magnitude. This leads to the conclusion that the limit capacity of a volume hologram of a radius r is only twice the capacity of a flat hologram of the same radius. Thus, increasing the hologram thickness beyond that securing required efficiency, does not deliver any practical gain in information capacity.

© 1992 Optical Society of America