Abstract

We present an optical architecture and image processor capable of detecting and locating temporally coherent radiation that may be dominated by incoherent background radiation. The optical architecture makes use of a coherent light modulator that modulates light of sufficient coherence length while it leaves light of short coherence length unmodulated. The design of the coherent light modulator offers a substantially wider field of view than did past designs, permitting its application within an imaging system. The image processor synchronously detects the modulation imposed on coherent light while it rejects incoherent light fluctuations. Results of a laboratory test are presented. The system tested in the laboratory had a 26° field of view and was able to detect and locate coherent radiation >30 dB below the background incoherent light level.

© 1997 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. J. Jannson, T. Jannson, E. Wolf, “Spatial coherence discrimination in scattering,” Opt. Lett. 13, 1060–1062 (1988).
    [CrossRef] [PubMed]
  2. R. Crane, “Laser detection by coherence discrimination,” Opt. Eng. 18, 212–217 (1979).
    [CrossRef]
  3. C. J. Duffy, D. Hickman, “A temporal coherence-based optical sensor,” Sensors Actuators 18, 17–31 (1989).
    [CrossRef]
  4. J. Cohen, “Electrooptic detector of temporally coherent radiation,” Appl. Opt. 30, 874–883 (1991).
    [CrossRef] [PubMed]
  5. R. Crane, “Imaging coherent radiometer,” U.S. patent4,735,507 (5April1988).
  6. M. Born, E. Wolf, Principles of Optics, 2nd ed. (Macmillan, New York, 1964), Chap. 14.

1991 (1)

1989 (1)

C. J. Duffy, D. Hickman, “A temporal coherence-based optical sensor,” Sensors Actuators 18, 17–31 (1989).
[CrossRef]

1988 (1)

1979 (1)

R. Crane, “Laser detection by coherence discrimination,” Opt. Eng. 18, 212–217 (1979).
[CrossRef]

Born, M.

M. Born, E. Wolf, Principles of Optics, 2nd ed. (Macmillan, New York, 1964), Chap. 14.

Cohen, J.

Crane, R.

R. Crane, “Laser detection by coherence discrimination,” Opt. Eng. 18, 212–217 (1979).
[CrossRef]

R. Crane, “Imaging coherent radiometer,” U.S. patent4,735,507 (5April1988).

Duffy, C. J.

C. J. Duffy, D. Hickman, “A temporal coherence-based optical sensor,” Sensors Actuators 18, 17–31 (1989).
[CrossRef]

Hickman, D.

C. J. Duffy, D. Hickman, “A temporal coherence-based optical sensor,” Sensors Actuators 18, 17–31 (1989).
[CrossRef]

Jannson, J.

Jannson, T.

Wolf, E.

Appl. Opt. (1)

Opt. Eng. (1)

R. Crane, “Laser detection by coherence discrimination,” Opt. Eng. 18, 212–217 (1979).
[CrossRef]

Opt. Lett. (1)

Sensors Actuators (1)

C. J. Duffy, D. Hickman, “A temporal coherence-based optical sensor,” Sensors Actuators 18, 17–31 (1989).
[CrossRef]

Other (2)

R. Crane, “Imaging coherent radiometer,” U.S. patent4,735,507 (5April1988).

M. Born, E. Wolf, Principles of Optics, 2nd ed. (Macmillan, New York, 1964), Chap. 14.

Cited By

OSA participates in CrossRef's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (10)

Fig. 1
Fig. 1

General system.

Fig. 2
Fig. 2

Optical system layout showing paths of rays from a point in the object plane to a point in the image plane.

Fig. 3
Fig. 3

Exploded view of the coherent light modulator.

Fig. 4
Fig. 4

Block diagram illustrating the processing of an individual pixel element of image n.

Fig. 5
Fig. 5

Experimental arrangement. The computer that performed the image processing is not shown.

Fig. 6
Fig. 6

Surface plots of the outputs of the image processor. A 50 × 50 array of pixels in the vicinity of the coherent illumination is displayed; (a) output proportional to H 1,m total(25), (b) output proportional to H 2,m total(25).

Fig. 7
Fig. 7

Surface plot of the input to the optical system.

Fig. 8
Fig. 8

Plot of the system processing gains G 1 and G 2, as a function of K, for the dominant pixel in Fig. 6 with λ = 633 nm illumination.

Fig. 9
Fig. 9

Plot of the system processing gains G 1 and G 2, as a function of K, for the dominant pixel in Fig. 6 with λ = 690 nm illumination.

Fig. 10
Fig. 10

Plot of effective processing gain versus the probability of false alarm for K = 25.

Equations (21)

Equations on this page are rendered with MathJax. Learn more.

γT=γv+γf,
It=12Γ0+Re Γγf+γvtc,
It=12Γ0; L  γf+γvtincoherent light,
It=12Γ01+cos2π γf+γvtλ; L  γf+γvtcoherent light,
γvt=γ0cos2πft+ϕ,
It=12Γ0+12Γ0cos2πγfλ J02π γ0λ+Γ0cos2π γfλk=1-1kJ2k2π γ0λ×cos2k2πft+ϕ-Γ0sin2π γfλ×k=0-1kJ2k+12π γ0λcos2k+12πft+ϕ.
h1=Γ0sin2πγfλJ12π γ0λ,
h2=Γ0cos2πγfλJ22π γ0λ,
1.42πγ0λ3.35.
γ0=0.31λc
ΔλB=0.82λc,
γvn=γ0 cos2πnN+ϕ,
smn=n-1τfnτfRImtΦdt,
H1,mK=n=0KN-1smnsin2πn/N2+n=0KN-1 smncos2πn/N21/2,
H2,mK=n=0KN-1smnsin4πn/N2+n=0KN-1 smncos4πn/N21/2,
H1,mK=NRΦτf2 Kh1,m
H2,mK=NRΦτf2 Kh2,m.
H1,mtotalK=H1,mcoh.K+H1,mincoh.K,
H2,mtotalK=H2,mcoh.K+H2,mincoh.K,
G1=H1,mcoh.KH1,mincoh.KPmcoh.Pmincoh.,
G2=H2,mcoh.KH2,mincoh.KPmcoh.Pmincoh.,

Metrics