Abstract

We present the design, fabrication, and testing of a novel liquid-crystal-on-silicon optically addressed spatial light modulator for use as a weight matrix in an ART-1 optoelectronic neural processor. Each pixel in the 50 × 83 element array occupies 75 μm × 75 μm and consists of a photodetector, a threshold circuit, a 1-bit (flip-flop) memory element, and a liquid-crystal modulating mirror. The array is designed to switch all the pixels initially to the ON state. Subsequently each pixel is independently switched to the OFF state if a superthreshold amount of light falls upon the pixel’s photodetector. The device has a contrast ratio of 20:1, a switch-on time (10–90% rise time) of 500 μs, and a switch-off time of ~500 μs (depending on the externally set threshold). Measured device uniformities and interpixel coupling are also described.

© 1995 Optical Society of America

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References

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  1. G. A. Carpenter, S. Grossberg, Computer Vision Graphics Image Process. 37, 54 (1987).
    [CrossRef]
  2. B. Moore, in Proceedings of the 1988 Connectionist Summer School, D. Tourenzky, G. Hinton, eds. (Morgan Kaufman, San Mateo, Calif., 1989).
  3. T. P. Caudell, S. Smith, C. Johnson, presented at the International Joint Conference on Neural Networks, Seattle, Wash., 1991.
  4. A. A. Baloch, A. M. Waxman, presented at the International Joint Conference on Neural Networks, San Diego, Calif., 1990.
  5. M. Rao, Neural Comput. 2, 35 (1989).
    [CrossRef]
  6. S. W. Tsay, R. Newcomb, IEEE Trans. Neural Networks 2, 214 (1991).
    [CrossRef]
  7. T. P. Caudell, Appl. Opt. 31, 6220 (1992).
    [CrossRef] [PubMed]
  8. K. M. Johnson, G. Moddel, Appl. Opt. 28, 4888 (1989).
    [CrossRef] [PubMed]
  9. K. M. Johnson, D. J. McKnight, I. Underwood, IEEE J. Quantum Electron. 29, 699 (1993).
    [CrossRef]
  10. For example, BDH SCE-13 ferroelectric liquid crystal.
  11. J. Xue, M. A. Handschy, N. A. Clark, Ferroelectrics 73, 305 (1987).
    [CrossRef]
  12. MOSIS, 4676 Admirality Way, Marina del Rey, Calif.

1993 (1)

K. M. Johnson, D. J. McKnight, I. Underwood, IEEE J. Quantum Electron. 29, 699 (1993).
[CrossRef]

1992 (1)

1991 (1)

S. W. Tsay, R. Newcomb, IEEE Trans. Neural Networks 2, 214 (1991).
[CrossRef]

1989 (2)

1987 (2)

G. A. Carpenter, S. Grossberg, Computer Vision Graphics Image Process. 37, 54 (1987).
[CrossRef]

J. Xue, M. A. Handschy, N. A. Clark, Ferroelectrics 73, 305 (1987).
[CrossRef]

Baloch, A. A.

A. A. Baloch, A. M. Waxman, presented at the International Joint Conference on Neural Networks, San Diego, Calif., 1990.

Carpenter, G. A.

G. A. Carpenter, S. Grossberg, Computer Vision Graphics Image Process. 37, 54 (1987).
[CrossRef]

Caudell, T. P.

T. P. Caudell, Appl. Opt. 31, 6220 (1992).
[CrossRef] [PubMed]

T. P. Caudell, S. Smith, C. Johnson, presented at the International Joint Conference on Neural Networks, Seattle, Wash., 1991.

Clark, N. A.

J. Xue, M. A. Handschy, N. A. Clark, Ferroelectrics 73, 305 (1987).
[CrossRef]

Grossberg, S.

G. A. Carpenter, S. Grossberg, Computer Vision Graphics Image Process. 37, 54 (1987).
[CrossRef]

Handschy, M. A.

J. Xue, M. A. Handschy, N. A. Clark, Ferroelectrics 73, 305 (1987).
[CrossRef]

Johnson, C.

T. P. Caudell, S. Smith, C. Johnson, presented at the International Joint Conference on Neural Networks, Seattle, Wash., 1991.

Johnson, K. M.

K. M. Johnson, D. J. McKnight, I. Underwood, IEEE J. Quantum Electron. 29, 699 (1993).
[CrossRef]

K. M. Johnson, G. Moddel, Appl. Opt. 28, 4888 (1989).
[CrossRef] [PubMed]

McKnight, D. J.

K. M. Johnson, D. J. McKnight, I. Underwood, IEEE J. Quantum Electron. 29, 699 (1993).
[CrossRef]

Moddel, G.

Moore, B.

B. Moore, in Proceedings of the 1988 Connectionist Summer School, D. Tourenzky, G. Hinton, eds. (Morgan Kaufman, San Mateo, Calif., 1989).

Newcomb, R.

S. W. Tsay, R. Newcomb, IEEE Trans. Neural Networks 2, 214 (1991).
[CrossRef]

Rao, M.

M. Rao, Neural Comput. 2, 35 (1989).
[CrossRef]

Smith, S.

T. P. Caudell, S. Smith, C. Johnson, presented at the International Joint Conference on Neural Networks, Seattle, Wash., 1991.

Tsay, S. W.

S. W. Tsay, R. Newcomb, IEEE Trans. Neural Networks 2, 214 (1991).
[CrossRef]

Underwood, I.

K. M. Johnson, D. J. McKnight, I. Underwood, IEEE J. Quantum Electron. 29, 699 (1993).
[CrossRef]

Waxman, A. M.

A. A. Baloch, A. M. Waxman, presented at the International Joint Conference on Neural Networks, San Diego, Calif., 1990.

Xue, J.

J. Xue, M. A. Handschy, N. A. Clark, Ferroelectrics 73, 305 (1987).
[CrossRef]

Appl. Opt. (2)

Computer Vision Graphics Image Process. (1)

G. A. Carpenter, S. Grossberg, Computer Vision Graphics Image Process. 37, 54 (1987).
[CrossRef]

Ferroelectrics (1)

J. Xue, M. A. Handschy, N. A. Clark, Ferroelectrics 73, 305 (1987).
[CrossRef]

IEEE J. Quantum Electron. (1)

K. M. Johnson, D. J. McKnight, I. Underwood, IEEE J. Quantum Electron. 29, 699 (1993).
[CrossRef]

IEEE Trans. Neural Networks (1)

S. W. Tsay, R. Newcomb, IEEE Trans. Neural Networks 2, 214 (1991).
[CrossRef]

Neural Comput. (1)

M. Rao, Neural Comput. 2, 35 (1989).
[CrossRef]

Other (5)

MOSIS, 4676 Admirality Way, Marina del Rey, Calif.

For example, BDH SCE-13 ferroelectric liquid crystal.

B. Moore, in Proceedings of the 1988 Connectionist Summer School, D. Tourenzky, G. Hinton, eds. (Morgan Kaufman, San Mateo, Calif., 1989).

T. P. Caudell, S. Smith, C. Johnson, presented at the International Joint Conference on Neural Networks, Seattle, Wash., 1991.

A. A. Baloch, A. M. Waxman, presented at the International Joint Conference on Neural Networks, San Diego, Calif., 1990.

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Figures (6)

Fig. 1
Fig. 1

ART-1 algorithm optoelectronic implementation schematic configuration (from Ref. 3).

Fig. 2
Fig. 2

Pixel block diagram.

Fig. 3
Fig. 3

Pixel circuit schematic: the circuit is a hybrid analog–digital; thresholding is the analog operation.

Fig. 4
Fig. 4

Pixel layout. The large size of the threshold transistor at the upper left-hand corner is to reduce interpixel nonuniformities.

Fig. 5
Fig. 5

Experimental results: single-pixel optical output, showing threshold circuit performance.

Fig. 6
Fig. 6

Experimental results: uniformity performance of the entire array at 3-V threshold.

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