Multi-layer opto-electronic neural network
First Claim
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.
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Abstract
A pattern recognition apparatus and a method for operating same. The apparatus includes a volume holographic medium (4) having a plurality of Fourier-space volume holograms representing pattern templates stored within. The apparatus further includes a spatial light modulator (1) and a phase encoder (2). The phase encoder has an output optically coupled to the medium by a first Fourier transform lens (3). The spatial light modulator spatially modulates a spatially uniform laser beam (7) in accordance with an unknown pattern. The two-dimensional phase encoder causes the spatially modulated laser beam to be spatially distributed prior to application to the medium. The apparatus also includes a detector (6, 11) having an input optically coupled by a second Fourier transform lens (5) means to an angular spectrum of plane waves generated by the medium in response to the output of the spatial modulator, phase encoder, and first Fourier lens. The detector detects plane waves that correspond to vector inner products generated within medium (4) in response to the unknown pattern. The apparatus further contains a means (12) for nonlinearly processing the output of detector (6, 11) and a means (13) by which the output of nonlinear processing means (12) may be temporarily stored.
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Citations
14 Claims
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1. A multi-layer opto-electronic neural network (MLOENN) pattern classification apparatus, comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for storing (K) Fourier-space holograms within a volume holographic medium, comprising the steps of, for K Fourier-space holograms ν
- .sup.(k,i) (k=1,2, . . . , N);
loading a weight vector ν
.sup.(k,n) into a spatial light modulator means using a predetermined and fixed lexicographic ordering scheme;spatially modulating a first plane-wave laser beam in accordance with the loaded weight vector; multiplying a light pattern transmitted by the spatial light modulator means in accordance with a random, two-dimensional phase encoding function; applying the phase-encoded light pattern, with a first Fourier transform lens means, to approximately a midpoint of the volume holographic medium so as to generate, at the midpoint, a Fourier transform of the phase-encoded light pattern while simultaneously applying a second plane-wave laser beam, which is temporally coherent with the first plane-wave laser beam, so as to illuminate the medium at an angle ψ
k to a z2 -axis of the medium and within a x2-z2 plane;forming a weight vector hologram ν
.sup.(k) within the medium;changing the angle ψ
k to an angle ψ
.sub.(k+1) ; andrepeating the preceding loading, spatially modulating, multiplying, applying, forming, and changing steps for each k=1,2, . . . , K until all ν
.sup.(k) have been stored in the medium. - View Dependent Claims (13)
- .sup.(k,i) (k=1,2, . . . , N);
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14. A method for generating vector inner products (ƒ
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k.sup.(i)) for accomplishing pattern recognition, comprising the steps of;
loading an unknown pattern vector σ
.sup.(i) (i=1,2, . . . , N) into a spatial light modulator means using a same pre-determined and fixed lexicographic ordering scheme that was initially employed to store a weight vector ν
.sup.(k,i) (k=1,2, . . . , K;
i=1,2, . . . , N) template into a volume holographic medium;spatially modulating a first plane-wave laser beam in accordance with the unknown pattern vector; employing a phase encoder means to multiply the spatially modulated first plane-wave laser beam by a random, two-dimensional phase encoding function; transmitting a phase encoded light pattern representative of the multiplied spatially modulated first plane-wave laser beam from the phase encoder means to a first Fourier transform lens means; generating within the volume holographic medium, with the first Fourier transform lens means, a Fourier transform of the phase encoded light pattern; generating, within the volume holographic medium, an angular spectrum of plane waves having amplitudes proportional to vector inner products σ
.sup.(i) •
ν
.sup.(k,i) (k=1,2, . . . , K;
i=1,2, . . . , N) and propagation angles of ψ
k (k=1,2, . . . , K) which correspond to reference angles ψ
k of a plane-wave coherent optical signal;focusing onto a detector means, with a second Fourier transform lens means, plane waves of the angular spectrum of plane waves generated within the volume holographic medium; reading out, from the detector means, signals representing vector inner products corresponding to the plane waves focused upon the detector means; serially and nonlinearly processing the output of the detector means; temporarily storing the nonlinearly processed output of the detector means;
feeding the temporarily stored output of the detector means back into the spatial modulating means for further neural network processing as input signals of a next pattern vector σ
.sup.(i+1) and reading out the temporarily stored output of the detector means as pattern recognition results.
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k.sup.(i)) for accomplishing pattern recognition, comprising the steps of;
Specification