Abstract

This paper describes a new type of optical processing based on the dynamic scattering effect in liquid crystals. It is possible to realize a binary spatial filter with nematic liquid crystals and to control the optical modes by voltage signals. A two-dimensional Walsh function is used for extracting properties of the input patterns. The realization of an 8 × 8 Walsh function filter with nematic liquid crystals is demonstrated. The contrast ratio is over 30 to 1. The variation in transparency is within ±3%. Experimental results show that it is possible to extract the properties of handwritten characters by detecting the intensity of light transmitted through both the input pattern and the liquid crystal filter.

© 1972 Optical Society of America

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References

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  1. H. F. Harmuth, Transmission of Information by Orthogonal Functions (Springer-Verlag, Berlin, 1969).
    [CrossRef]
  2. J. A. Decker, Appl. Opt. 9, 1392 (1970).
    [CrossRef] [PubMed]
  3. A. N. Mucciadri, E. E. Gose, IEEE Trans. EC-15, 257 (1966).
  4. W. K. Pratt et al., Proc. IEEE 57, 58 (1969).
    [CrossRef]
  5. G. H. Heilmeier et al., Proc. IEEE 56, 1162 (1968).
    [CrossRef]
  6. J. A. Van Raalte, Proc. IEEE 56, 2146 (1968).
    [CrossRef]
  7. R. A. Soref, Appl. Opt. 9, 1323 (1970).
    [CrossRef] [PubMed]

1970 (2)

1969 (1)

W. K. Pratt et al., Proc. IEEE 57, 58 (1969).
[CrossRef]

1968 (2)

G. H. Heilmeier et al., Proc. IEEE 56, 1162 (1968).
[CrossRef]

J. A. Van Raalte, Proc. IEEE 56, 2146 (1968).
[CrossRef]

1966 (1)

A. N. Mucciadri, E. E. Gose, IEEE Trans. EC-15, 257 (1966).

Decker, J. A.

Gose, E. E.

A. N. Mucciadri, E. E. Gose, IEEE Trans. EC-15, 257 (1966).

Harmuth, H. F.

H. F. Harmuth, Transmission of Information by Orthogonal Functions (Springer-Verlag, Berlin, 1969).
[CrossRef]

Heilmeier, G. H.

G. H. Heilmeier et al., Proc. IEEE 56, 1162 (1968).
[CrossRef]

Mucciadri, A. N.

A. N. Mucciadri, E. E. Gose, IEEE Trans. EC-15, 257 (1966).

Pratt, W. K.

W. K. Pratt et al., Proc. IEEE 57, 58 (1969).
[CrossRef]

Soref, R. A.

Van Raalte, J. A.

J. A. Van Raalte, Proc. IEEE 56, 2146 (1968).
[CrossRef]

Appl. Opt. (2)

IEEE Trans. (1)

A. N. Mucciadri, E. E. Gose, IEEE Trans. EC-15, 257 (1966).

Proc. IEEE (3)

W. K. Pratt et al., Proc. IEEE 57, 58 (1969).
[CrossRef]

G. H. Heilmeier et al., Proc. IEEE 56, 1162 (1968).
[CrossRef]

J. A. Van Raalte, Proc. IEEE 56, 2146 (1968).
[CrossRef]

Other (1)

H. F. Harmuth, Transmission of Information by Orthogonal Functions (Springer-Verlag, Berlin, 1969).
[CrossRef]

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Figures (10)

Fig. 1
Fig. 1

Two-dimensional Walsh function filter.

Fig. 2
Fig. 2

Filter logic of modified Walsh function.

Fig. 3
Fig. 3

Transmitted light intensity vs applied voltage.

Fig. 4
Fig. 4

Contrast ratio vs distance.

Fig. 5
Fig. 5

Liquid crystal filter.

Fig. 6
Fig. 6

Liquid crystal filter.

Fig. 7
Fig. 7

Logic diagram of Walsh function generator.

Fig. 8
Fig. 8

Optical configuration.

Fig. 9
Fig. 9

Experimental result.

Fig. 10
Fig. 10

Response time.

Equations (3)

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w a l ( 2 p + q , x ) = ( - 1 ) ( p / 2 + q ) { w a l [ p , 2 ( x + 1 4 ) ] + ( - 1 ) p + q w a l [ p , 2 ( x - 1 4 ) ] } ,
F ( μ , ν ) = 0 1 0 1 f ( x , y ) w a l ( μ , x ) w a l ( ν , y ) d x d y ,
F m ( μ , ν ) = [ F ( 0 , 0 ) + F ( μ , ν ) ] / 2.

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