1. A multi-layer opto-electronic neural network (MLOENN) pattern classification apparatus, comprising: a volume holographic medium having a plurality of Fourier-space volume holograms representing neural network weight vectors stored within; means, having an output optically coupled to said medium by a first Fourier transform lens means, for spatially modulating a spatially uniform laser beam in accordance with an unknown pattern; means, having an input optically coupled by a second Fourier transform lens means to an angular spectrum of plane waves generated by said medium in response to the output of said spatial modulating means, for detecting plane waves that correspond to vector inner products generated within said medium in response to the unknown pattern; means by which the output of said detecting means are nonlinearly processed in a serial manner; means by which said nonlinearly processed output is temporarily stored; and means by which the output of said temporary storage means may be selectively read out and selectively fed back into said spatial modulating means for further processing by the MLOENN as input signals to a next layer of the MLOENN.