Abstract

We demonstrate an optical filter that displays the time-dependent features of a scene. The heart of the device is an interferometer that is sensitive not to the difference between two optical paths lengths but to changes in the path-length difference. The interferometer arms share a phase-conjugating mirror. The phase conjugator ensures that, at steady state, the output of the interferometer is dark. The response of the interferometer to a step differential change in the optical lengths is a decaying exponential having a time constant governed by the time response of the phase conjugator. The interferometer may be used to monitor time- and space-dependent optical phase changes that are due, for example, to transparent fluid motion. With a modified liquid-crystal television used as a spatial light phase modulator in the interferometer, we detect time-dependent features of an image viewed by a video camera.

© 1987 Optical Society of America

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References

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  1. T. Kohonen, Self-Organization and Associative Memory (Springer-Verlag, New York, 1984), Chap. 4.
  2. A. Hodges, Alan Turing: The Enigma (Simon & Schuster, New York, 1983), p. 315.
  3. M. D. Ewbank, P. Yeh, M. Khoshnevisan, J. Feinberg, Opt. Lett. 10, 282 (1985).
    [Crossref] [PubMed]
  4. An interferometer arrangement similar to ours has been used to perform real-time image subtraction. See S. Kwong, G. A. Rakuljic, A. Yariv, Appl. Phys. Lett. 48, 201 (1986); see also A. E. Chiou, P. Yeh, Opt. Lett. 11, 306 (1986).
    [Crossref] [PubMed]
  5. R. A. Fisher, ed., Optical Phase Conjugation (Academic, New York, 1983).
  6. J. Feinberg, Opt. Lett. 7, 486 (1982).
    [Crossref] [PubMed]
  7. I. McMichael, M. Khoshnevisan, P. Yeh, Opt. Lett. 11, 525 (1986).
    [Crossref] [PubMed]

1986 (2)

An interferometer arrangement similar to ours has been used to perform real-time image subtraction. See S. Kwong, G. A. Rakuljic, A. Yariv, Appl. Phys. Lett. 48, 201 (1986); see also A. E. Chiou, P. Yeh, Opt. Lett. 11, 306 (1986).
[Crossref] [PubMed]

I. McMichael, M. Khoshnevisan, P. Yeh, Opt. Lett. 11, 525 (1986).
[Crossref] [PubMed]

1985 (1)

1982 (1)

Ewbank, M. D.

Feinberg, J.

Hodges, A.

A. Hodges, Alan Turing: The Enigma (Simon & Schuster, New York, 1983), p. 315.

Khoshnevisan, M.

Kohonen, T.

T. Kohonen, Self-Organization and Associative Memory (Springer-Verlag, New York, 1984), Chap. 4.

Kwong, S.

An interferometer arrangement similar to ours has been used to perform real-time image subtraction. See S. Kwong, G. A. Rakuljic, A. Yariv, Appl. Phys. Lett. 48, 201 (1986); see also A. E. Chiou, P. Yeh, Opt. Lett. 11, 306 (1986).
[Crossref] [PubMed]

McMichael, I.

Rakuljic, G. A.

An interferometer arrangement similar to ours has been used to perform real-time image subtraction. See S. Kwong, G. A. Rakuljic, A. Yariv, Appl. Phys. Lett. 48, 201 (1986); see also A. E. Chiou, P. Yeh, Opt. Lett. 11, 306 (1986).
[Crossref] [PubMed]

Yariv, A.

An interferometer arrangement similar to ours has been used to perform real-time image subtraction. See S. Kwong, G. A. Rakuljic, A. Yariv, Appl. Phys. Lett. 48, 201 (1986); see also A. E. Chiou, P. Yeh, Opt. Lett. 11, 306 (1986).
[Crossref] [PubMed]

Yeh, P.

Appl. Phys. Lett. (1)

An interferometer arrangement similar to ours has been used to perform real-time image subtraction. See S. Kwong, G. A. Rakuljic, A. Yariv, Appl. Phys. Lett. 48, 201 (1986); see also A. E. Chiou, P. Yeh, Opt. Lett. 11, 306 (1986).
[Crossref] [PubMed]

Opt. Lett. (3)

Other (3)

R. A. Fisher, ed., Optical Phase Conjugation (Academic, New York, 1983).

T. Kohonen, Self-Organization and Associative Memory (Springer-Verlag, New York, 1984), Chap. 4.

A. Hodges, Alan Turing: The Enigma (Simon & Schuster, New York, 1983), p. 315.

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Figures (4)

Fig. 1
Fig. 1

An optical tracking novelty filter incorporating a spatial phase modulator. B.S., beam splitter; PC, phase conjugating.

Fig. 2
Fig. 2

An optical tracking novelty filter incorporating a spatial polarization modulator.

Fig. 3
Fig. 3

Response of the polarization interferometer to a step change of the polarization. The lower curve is proportional to the voltage on a Pockels cell used to switch the polarization. The amplitude corresponds to a round-trip polarization flip of 90°. The upper curve is the output from the interferometer. The top of the grid represents zero light intensity. Detected output yields a negative voltage.

Fig. 4
Fig. 4

Photographs of the output of the tracking novelty filter shown in Fig. 2. Input to the LCTV is taken from a character generator driving a video camera. (a) The character generator is off; the interferometer output is essentially dark. (b) The character-generator display, showing the phrase NOVELTY FILTER, is activated. (c) The filter adapts to the new scene and becomes nearly blank, as in (a). Some letters are visible. (d) The character-generator display is deactivated. The previous phrase appears again at the output of the interferometer. Shortly thereafter it fades to (a).

Equations (1)

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( I max - I min ) / I max ,

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