Abstract

We have developed a fast and high-accuracy three-dimensional (3-D) imaging laser radar that can achieve better than 1-mm range accuracy for half a million pixels in less than 1 s. Our technique is based on range-gating segmentation. We combine the advantages of gated viewing with our new fast technique of 3-D imaging. The system uses a picosecond Q-switched Nd:Yag laser at 532 nm with a 32-kHz pulse repetition frequency (PRF), which triggers an ultrafast camera with a highly sensitive CCD with 582 × 752 pixels. The high range accuracy is achieved with narrow laser pulse widths of approximately 200 ps, a high PRF of 32 kHz, and a high-speed camera with gate times down to 200 ps and delay steps down to 100 ps. The electronics and the software also allow for gated viewing with automatic gain control versus range, whereby foreground backscatter can be suppressed. We describe our technique for the rapid production of high-accuracy 3-D images, derive performance characteristics, and outline future improvements.

© 2004 Optical Society of America

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References

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  1. B. W. Schilling, D. N. Barr, G. C. Templeton, L. J. Mizerka, C. W. Trussell, “Multiple-return laser radar for three-dimensional imaging through obscurations,” Appl. Opt. 41, 2791–2799 (2002).
    [CrossRef] [PubMed]
  2. R. G. Driggers, R. H. Vollmerhausen, N. Devitt, C. Halford, K. J. Barnard, “Impact of speckle on laser range-gated shortwave infrared imaging system target identification performance,” Opt. Eng. 42, 738–746 (2003).
    [CrossRef]
  3. M. A. Albota, R. M. Heinrich, D. G. Kocher, D. G. Fouche, B. E. Player, M. E. O’Brien, B. F. Aull, J. J. Zayhowski, J. Mooney, B. C. Willard, R. R. Carlson, “Three-dimensional imaging laser radar with a photon-counting avalanche photodiode array and microchip laser,” Appl. Opt. 41, 7671–7678 (2002).
    [CrossRef]
  4. G. R. Fournier, D. Bonnier, J. L. Forand, P. W. Pace, “Range-gated underwater laser imaging system,” Opt. Eng. 32, 2185–2190 (1993).
    [CrossRef]
  5. J. W. McLean, “High resolution 3-D underwater imaging,” in Airborne and In-Water Underwater Imaging, G. D. Gilbert, ed., Proc. SPIE3761, 10–19 (1999).
    [CrossRef]
  6. R. Stettner, H. Bailey, “Staring underwater laser radar (SULAR) 3-D imaging,” in Laser Radar Technology and Applications VI, G. W. Kamerman, ed., Proc. SPIE4377, 57–64 (2001).
    [CrossRef]
  7. C. S. Fox, “Active electro-optical systems,” in IR/EO System Handbook (SPIE Press, Bellingham, Wash., 1993), Vol. 6.

2003 (1)

R. G. Driggers, R. H. Vollmerhausen, N. Devitt, C. Halford, K. J. Barnard, “Impact of speckle on laser range-gated shortwave infrared imaging system target identification performance,” Opt. Eng. 42, 738–746 (2003).
[CrossRef]

2002 (2)

1993 (1)

G. R. Fournier, D. Bonnier, J. L. Forand, P. W. Pace, “Range-gated underwater laser imaging system,” Opt. Eng. 32, 2185–2190 (1993).
[CrossRef]

Albota, M. A.

Aull, B. F.

Bailey, H.

R. Stettner, H. Bailey, “Staring underwater laser radar (SULAR) 3-D imaging,” in Laser Radar Technology and Applications VI, G. W. Kamerman, ed., Proc. SPIE4377, 57–64 (2001).
[CrossRef]

Barnard, K. J.

R. G. Driggers, R. H. Vollmerhausen, N. Devitt, C. Halford, K. J. Barnard, “Impact of speckle on laser range-gated shortwave infrared imaging system target identification performance,” Opt. Eng. 42, 738–746 (2003).
[CrossRef]

Barr, D. N.

Bonnier, D.

G. R. Fournier, D. Bonnier, J. L. Forand, P. W. Pace, “Range-gated underwater laser imaging system,” Opt. Eng. 32, 2185–2190 (1993).
[CrossRef]

Carlson, R. R.

Devitt, N.

R. G. Driggers, R. H. Vollmerhausen, N. Devitt, C. Halford, K. J. Barnard, “Impact of speckle on laser range-gated shortwave infrared imaging system target identification performance,” Opt. Eng. 42, 738–746 (2003).
[CrossRef]

Driggers, R. G.

R. G. Driggers, R. H. Vollmerhausen, N. Devitt, C. Halford, K. J. Barnard, “Impact of speckle on laser range-gated shortwave infrared imaging system target identification performance,” Opt. Eng. 42, 738–746 (2003).
[CrossRef]

Forand, J. L.

G. R. Fournier, D. Bonnier, J. L. Forand, P. W. Pace, “Range-gated underwater laser imaging system,” Opt. Eng. 32, 2185–2190 (1993).
[CrossRef]

Fouche, D. G.

Fournier, G. R.

G. R. Fournier, D. Bonnier, J. L. Forand, P. W. Pace, “Range-gated underwater laser imaging system,” Opt. Eng. 32, 2185–2190 (1993).
[CrossRef]

Fox, C. S.

C. S. Fox, “Active electro-optical systems,” in IR/EO System Handbook (SPIE Press, Bellingham, Wash., 1993), Vol. 6.

Halford, C.

R. G. Driggers, R. H. Vollmerhausen, N. Devitt, C. Halford, K. J. Barnard, “Impact of speckle on laser range-gated shortwave infrared imaging system target identification performance,” Opt. Eng. 42, 738–746 (2003).
[CrossRef]

Heinrich, R. M.

Kocher, D. G.

McLean, J. W.

J. W. McLean, “High resolution 3-D underwater imaging,” in Airborne and In-Water Underwater Imaging, G. D. Gilbert, ed., Proc. SPIE3761, 10–19 (1999).
[CrossRef]

Mizerka, L. J.

Mooney, J.

O’Brien, M. E.

Pace, P. W.

G. R. Fournier, D. Bonnier, J. L. Forand, P. W. Pace, “Range-gated underwater laser imaging system,” Opt. Eng. 32, 2185–2190 (1993).
[CrossRef]

Player, B. E.

Schilling, B. W.

Stettner, R.

R. Stettner, H. Bailey, “Staring underwater laser radar (SULAR) 3-D imaging,” in Laser Radar Technology and Applications VI, G. W. Kamerman, ed., Proc. SPIE4377, 57–64 (2001).
[CrossRef]

Templeton, G. C.

Trussell, C. W.

Vollmerhausen, R. H.

R. G. Driggers, R. H. Vollmerhausen, N. Devitt, C. Halford, K. J. Barnard, “Impact of speckle on laser range-gated shortwave infrared imaging system target identification performance,” Opt. Eng. 42, 738–746 (2003).
[CrossRef]

Willard, B. C.

Zayhowski, J. J.

Appl. Opt. (2)

Opt. Eng. (2)

R. G. Driggers, R. H. Vollmerhausen, N. Devitt, C. Halford, K. J. Barnard, “Impact of speckle on laser range-gated shortwave infrared imaging system target identification performance,” Opt. Eng. 42, 738–746 (2003).
[CrossRef]

G. R. Fournier, D. Bonnier, J. L. Forand, P. W. Pace, “Range-gated underwater laser imaging system,” Opt. Eng. 32, 2185–2190 (1993).
[CrossRef]

Other (3)

J. W. McLean, “High resolution 3-D underwater imaging,” in Airborne and In-Water Underwater Imaging, G. D. Gilbert, ed., Proc. SPIE3761, 10–19 (1999).
[CrossRef]

R. Stettner, H. Bailey, “Staring underwater laser radar (SULAR) 3-D imaging,” in Laser Radar Technology and Applications VI, G. W. Kamerman, ed., Proc. SPIE4377, 57–64 (2001).
[CrossRef]

C. S. Fox, “Active electro-optical systems,” in IR/EO System Handbook (SPIE Press, Bellingham, Wash., 1993), Vol. 6.

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Figures (6)

Fig. 1
Fig. 1

Gated viewing technique. The laser emits a pulse and triggers the camera with a delay and a gate time, which determine when and how long the camera gate opens. Approximately 650 laser pulses are integrated in each time slice after the delay is changed [sliding, as given by Eq. (1)]. Each time slice is read out within 50-Hz video mode, i.e., the pulse repetition frequency is equal to 50 time slices per second × 650 laser pulses per time slice, or 32.5 kHz.

Fig. 2
Fig. 2

Measured curves I i [from Eq. (3)], with time step Δt = 100 ps but different camera gates: t gate = 0.3, 0.4, …, 1.0 ns. The amplitude of the 0.3-ns curve is relatively small, because the camera gate starts to close before it is fully open. When the gate time is increased the laser pulses can make it back in earlier time slices, and therefore the intensity curves extend to a smaller image number. The background value is ∼25 and will be subtracted in further analysis.

Fig. 3
Fig. 3

Image of I(x, y) at the range of 13.55 m of a 15-cm-high doll’s head.

Fig. 4
Fig. 4

The image of Fig. 3 wrapped onto a 3-D image recorded by the time-slicing technique described in the text. The 3-D image is then computer rotated by 60° to the side. Camera gate time is 400 ps, and delay step is 100 ps. Note: the range deviation of the eye pixels is strongly related to the pixel SNR, the subtracted background, the noise, and the timing of the 2-D image sequence.

Fig. 5
Fig. 5

Rotated range (r) image. The range in meters is color coded.

Fig. 6
Fig. 6

Variance (σ2) image. The variance is color coded in units of square nanoseconds.

Equations (14)

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ti=t0+iΔt.
Pt=P02πσpulseexp-t2/2σpulse2.
Ii= Pt-2r/cGt-tidt.
I=i IitgateΔt P0.
t=2rc=I-1i Iiti,
t2=I-1i Iiti2
σ2=t2-t2=Δt2i2-i2,
σ2=t2-t2σpulse2+σgate2.
SNR2=I=σΔtmaxIi,
Δr12cσSNR,
ti= dti  dtPtGti-tti,
ti= dτ  dtPtGττ+t=tP+τG,
ti2= dτ  dtPtGττ+t2=t2P+τ2G+2tPτG.
σ2ti2-ti2=t2P-tP2+τ2G-τG2=σP2+σG2.

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