Abstract

In this paper, we proposed a parallel phase-only lensless optical correlator based on two pieces of Liquid Crystal on Silicon Spatial Light Modulators. Phase Fresnel Lens Array and specialized grating are implemented to realize multi-channel and multiplexed LOC. Experimental results of Chinese characters’ recognitions are given as demonstration of proposed technique. High uniformity of processing channels has been verified by autocorrelation process of four same Chinese characters. The technique is programmable and adjustment of optical path could be realized without changing of optical setup. The implementations could be performed on the same configuration as single channel optical correlator without mechanical alternation.

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References

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  1. F. T. S. Yu and X. J. Lu, “Real-time optical scanning correlator,” Appl. Opt. 23(18), 3109–3116 (1984).
    [CrossRef] [PubMed]
  2. F. T. S. Yu and M. S. Dymek, “Optical information parallel processing: a technique,” Appl. Opt. 20(8), 1450–1453 (1981).
    [CrossRef] [PubMed]
  3. D. A. Gregory and H. K. Liu, “Large-memory real-time multichannel multiplexed pattern recognition,” Appl. Opt. 23(24), 4560–4570 (1984).
    [CrossRef] [PubMed]
  4. H. K. Liu and J. G. Duthie, “Real-time screen-aided multiple-image optical holographic matched-filter correlator,” Appl. Opt. 21(18), 3278–3286 (1982).
    [CrossRef] [PubMed]
  5. T. H. Chao and H. K. Liu, “Real-time optical holographic tracking of multiple objects,” Appl. Opt. 28(2), 226–231 (1989).
    [CrossRef] [PubMed]
  6. S. K. Case, “Pattern recognition with wavelength-multiplexed filters,” Appl. Opt. 18(12), 1890–1894 (1979).
    [CrossRef] [PubMed]
  7. T. H. Chao and M. Chen, “Pattern recognition with a wavelength-angle multiplexed optical scanning correlator,” Opt. Eng. 25, 828–833 (1986).
  8. C. F. Hester and D. Casasent, “Multivariant technique for multiclass pattern recognition,” Appl. Opt. 19(11), 1758–1761 (1980).
    [CrossRef] [PubMed]
  9. G. F. Schils and D. W. Sweeney, “Rotationally invariant correlation filtering for multiple images,” J. Opt. Soc. Am. A 3(7), 902–908 (1986).
    [CrossRef]
  10. M. Villarreal, C. Iemmi, and J. Campos, “Parallel classification of multiple objects using a phase-only multichannel optical correlator,” Opt. Eng. 42(8), 2354–2361 (2003).
    [CrossRef]
  11. N. Fukuchi, T. Inoue, H. Toyoda, and T. Hara, “Lensless Vanderlugt optical correlator using two phase-only spatial light modulators,” Chin. Opt. Lett. 7(12), 1131–1133 (2009).
    [CrossRef]
  12. X. Zeng, J. Bai, C. Hou, and G. Yang, “Compact optical correlator based on one phase-only spatial light modulator,” Opt. Lett. 36(8), 1383–1385 (2011).
    [CrossRef] [PubMed]
  13. R. W. Gerchberg and W. O. Saxton, “A practical algorithm for the determination of the phase from image and diffraction plane pictures,” Optik (Stuttg.) 35, 227–246 (1972).

2011 (1)

2009 (1)

2003 (1)

M. Villarreal, C. Iemmi, and J. Campos, “Parallel classification of multiple objects using a phase-only multichannel optical correlator,” Opt. Eng. 42(8), 2354–2361 (2003).
[CrossRef]

1989 (1)

1986 (2)

G. F. Schils and D. W. Sweeney, “Rotationally invariant correlation filtering for multiple images,” J. Opt. Soc. Am. A 3(7), 902–908 (1986).
[CrossRef]

T. H. Chao and M. Chen, “Pattern recognition with a wavelength-angle multiplexed optical scanning correlator,” Opt. Eng. 25, 828–833 (1986).

1984 (2)

1982 (1)

1981 (1)

1980 (1)

1979 (1)

1972 (1)

R. W. Gerchberg and W. O. Saxton, “A practical algorithm for the determination of the phase from image and diffraction plane pictures,” Optik (Stuttg.) 35, 227–246 (1972).

Bai, J.

Campos, J.

M. Villarreal, C. Iemmi, and J. Campos, “Parallel classification of multiple objects using a phase-only multichannel optical correlator,” Opt. Eng. 42(8), 2354–2361 (2003).
[CrossRef]

Casasent, D.

Case, S. K.

Chao, T. H.

T. H. Chao and H. K. Liu, “Real-time optical holographic tracking of multiple objects,” Appl. Opt. 28(2), 226–231 (1989).
[CrossRef] [PubMed]

T. H. Chao and M. Chen, “Pattern recognition with a wavelength-angle multiplexed optical scanning correlator,” Opt. Eng. 25, 828–833 (1986).

Chen, M.

T. H. Chao and M. Chen, “Pattern recognition with a wavelength-angle multiplexed optical scanning correlator,” Opt. Eng. 25, 828–833 (1986).

Duthie, J. G.

Dymek, M. S.

Fukuchi, N.

Gerchberg, R. W.

R. W. Gerchberg and W. O. Saxton, “A practical algorithm for the determination of the phase from image and diffraction plane pictures,” Optik (Stuttg.) 35, 227–246 (1972).

Gregory, D. A.

Hara, T.

Hester, C. F.

Hou, C.

Iemmi, C.

M. Villarreal, C. Iemmi, and J. Campos, “Parallel classification of multiple objects using a phase-only multichannel optical correlator,” Opt. Eng. 42(8), 2354–2361 (2003).
[CrossRef]

Inoue, T.

Liu, H. K.

Lu, X. J.

Saxton, W. O.

R. W. Gerchberg and W. O. Saxton, “A practical algorithm for the determination of the phase from image and diffraction plane pictures,” Optik (Stuttg.) 35, 227–246 (1972).

Schils, G. F.

Sweeney, D. W.

Toyoda, H.

Villarreal, M.

M. Villarreal, C. Iemmi, and J. Campos, “Parallel classification of multiple objects using a phase-only multichannel optical correlator,” Opt. Eng. 42(8), 2354–2361 (2003).
[CrossRef]

Yang, G.

Yu, F. T. S.

Zeng, X.

Appl. Opt. (7)

Chin. Opt. Lett. (1)

J. Opt. Soc. Am. A (1)

Opt. Eng. (2)

T. H. Chao and M. Chen, “Pattern recognition with a wavelength-angle multiplexed optical scanning correlator,” Opt. Eng. 25, 828–833 (1986).

M. Villarreal, C. Iemmi, and J. Campos, “Parallel classification of multiple objects using a phase-only multichannel optical correlator,” Opt. Eng. 42(8), 2354–2361 (2003).
[CrossRef]

Opt. Lett. (1)

Optik (Stuttg.) (1)

R. W. Gerchberg and W. O. Saxton, “A practical algorithm for the determination of the phase from image and diffraction plane pictures,” Optik (Stuttg.) 35, 227–246 (1972).

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Figures (9)

Fig. 1
Fig. 1

(color online) Basic configuration of multichannel (a) and multiplexed (b) LOC. SLM1 and SLM2 are parallel positioned. Collimated beam propagates between SLM1 and SLM2 along a zig-zag path and the correlation results are observed by a CCD camera.

Fig. 2
Fig. 2

Schematic diagram of constructing input pattern of multichannel LOC. The input targets are N × N targets array represented as T ( i , j ) (i, j = 0, 1, 2 … N). The FLA is consisted of N × N FLPs. The input pattern is created by adding input targets and FLA.

Fig. 3
Fig. 3

Principle of constructing the filter pattern in parallel LOC. The N × N reference target array denoted as R ( i , j ) (i, j = 0, 1, 2 … N) is phase-encode. Phase-only filter array F ( i , j ) is created by Fourier transforming of individual reference targets. The filter pattern is attained by adding a FLA with the phase-only filter array.

Fig. 4
Fig. 4

Basic procedure to create the Type I input pattern of multiplexed LOC. By adding the input targets T k with frequency carriers G k in complex value, the spectrum of input targets could be split onto corresponding channel on SLM2, as illustrated in Fig. 1(b).

Fig. 5
Fig. 5

Principle to construct the input pattern of Type II multiplexed LOC, where the input target T is superimposed with a specific grating G in complex value. The phase part I of superimposing image is overlapped with a FLP to form the input pattern.

Fig. 6
Fig. 6

Input targets (a) are composed of four same Chinese characters, reference targets (b) is consist of four different Chinese characters’ parts represented as 1, 2, 3, 4, where reference target 1, 2, and 3 are intercepted from the input character and reference target 4 is selected randomly. The white cross lines on input and reference targets are drew for isolating the different channels, which is not displayed on SLM. The correlation signals between (a) and (b) is obtained by a CCD camera shown in (c).

Fig. 7
Fig. 7

Experimental results and patterns of 4-channel multiplexed LOC. (a) shows the input targets in the left column, the corresponding high frequency carriers in the middle column, which are retrieved from the spot patterns in the right column. The reference targets (b) are four same Chinese characters, which are identical to the input target at row 2. On the correlation plane (c), a strong correlation peak can be observed at the right-up.

Fig. 8
Fig. 8

Experimental results and input target to demonstrate Type II multiplexed LOC. Input target is one Chinese character (left image in (a)). The frequency carrier (middle image in (a)) is retrieved from the four spots pattern (right image in (a)). On the correlation plane (c), three correlation peaks can be observed at the position denoted as 1, 2 and 3. No obvious signal is appeared on part 4.

Fig. 9
Fig. 9

Autocorrelation results of the Chinese characters in Fig. 6(a). (a) multichannel LOC (b) multiplexed LOC.

Tables (2)

Tables Icon

Table 1 Normalized Correlation Signal Intensity of Four-Channel LOC in Fig. 9(a)

Tables Icon

Table 2 Normalized Correlation Signal Intensity of Four-Channel Multiplexed LOC in Fig. 9(b)

Equations (13)

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S B P = H x H y f x f y
f x = 1 / ( 2 d x )
f y = 1 / ( 2 d y )
f x = f y
H = M d
S B P = M 2 / 4
D i = λ f / d
D f = M d / N
f = K M d 2 / ( λ N )
f min = ( r m 2 - r m - 1 2 ) / ( 2 λ )
f min = 2 r m d / λ
r m = M d / ( 2 N )
f min = M d 2 / ( λ N )

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