Performance considerations for continuous-wave and pulsed laser line scan (LLS) imaging systems

F. M. Caimi; F. R. Dalgleish

doi:10.2971/jeos.2010.10020s

Journal of the European Optical Society - Rapid publications, Vol 5 (2010)

Performance considerations for continuous-wave and pulsed laser line scan (LLS) imaging systems

F. M. Caimi, F. R. Dalgleish

Abstract

Extended range underwater optical imaging techniques can be classified into one of two broad categories; those which use synchronously scanned narrow source and receiver paths to restrict both back-scattered and forward-scattered light reaching the receiver (continuous-wave laser line scan); and those which use pulsed sources and time-gating to remove back-scatter noise (pulsed laser line scan and pulse-gated laser line scan). Laser line scan systems are observed to perform at up to 5 to 6 optical attenuation lengths, but greater standoff distances are desirable for seabed imaging using the growing fleet of autonomous underwater vehicles (AUVs). Currently, a moderate physical separation between laser and receiver is necessary to reject near-field multiple back-scatter, which imposes restrictions on AUV miniaturization. Recent experiments and theoretical modeling reveal that significant imaging improvements are possible over the existing continuous-wave laser line scan systems (LLS), by using a pulsed-gated version of the LLS (PG-LLS). However, the use of such a technique has a greater advantage in reducing the overall form factor over conventional LLS imaging system, as well as providing greater depth-of-field. In this paper, we present experimental results comparing both LLS and PG-LLS systems for several source-receiver separations and standoff distances. These results compare favorably with images obtained from validated LLS image simulation tools, and indicate the potential for reducing the source-receiver separation and therefore the system size.

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References

M. P. Strand, Quantitative evaluation of environmental noise in underwater electro-optic imaging systems (Ocean Optics XIV, Kailua- Kona, Hawaii, 10-13 November 1998).

T. J. Kulp, D. Garvis, R. Kennedy, T. Salmon, and K. Cooper, "Results of the final tank test of the LLNL/NAVSEA Synchronous-Scanning Underwater Laser Imaging System" Proc. SPIE 1750, 453-464 (1992).

A. Gordon, Turbid test results of the SM2000 laser line scan system and low light level underwater camera tests (Underwater Intervention '94: Man and Machine Underwater, Marine Technology Society, Washington D.C., 305-311, 1994).

M. P. Strand, "Underwater electro-optical system for mine identification" Proc. SPIE 2496, 487-497 (1995).

A. Laux, L. J. Mullen, and B. Cochenour, A comparison of extended range laser line scan imaging techniques in turbid underwater environments (Ocean Optics XIX, Il Ciocco, 6-10 October 2008).

E. A. McLean, H. R. Burris, and M. P. Strand, "Short-pulse rangegated optical imaging in turbid water" Appl. Opt. 34, 4343-4351 (1995).

B. A. Swartz, Diver and ROV deployable laser range gated underwater imaging systems (Underwater Intervention '93, Marine Technology Society and Association of Diving Contractors, New Orleans, 1993).

N. H. Witherspoon, and J. H. Holloway, "Feasibility testing of a range-gated laser-illuminated underwater imaging system" Proc. SPIE 1302, 414 (1990).

G. R. Fournier, D. Bonnier, J. L. Forand, and P. W. Pace, "Rangegated underwater laser imaging system" Opt. Eng. 32, 2185-2190 (1993).

J. Busck, "Underwater 3-D optical imaging with a gated viewing laser radar" Opt. Eng. 44, 116001 (2005).

F. M. Caimi, F. R. Dalgleish, T. E. Giddings, J. J. Shirron, C. H. Mazel, and K. Chiang, Pulse versus CW laser line scan imaging detection methods: simulation results (IEEE/OES Oceans Oceans '07, Aberdeen, 18-21 June 2007).

F. R. Dalgleish, F. M. Caimi, C. H. Mazel, J. M. Glynn, K. Chiang, T. E. Giddings, and J. J. Shirron, Model-based evaluation of pulsed lasers for an underwater laser line scan imager (Ocean Optics XVIII, Montreal, 9-13 October 2006).

F. R. Dalgleish, F. M. Caimi, C. H. Mazel, and J. M. Glynn, Extended range underwater optical imaging architecture (MTS/IEEE Oceans '06, Boston, 18-21 September 2006).

T. E. Giddings, and J. J. Shirron, "Numerical simulation of the incoherent electro-optical imaging process in plane-stratified media" Opt. Eng. 48, 126001 (2009).

F. M. Caimi, Private communication with Brian Coles (Raytheon, 1993).

F. M. Caimi, and F. R. Dalgleish, Performance considerations for laser line scan (LLS) imaging systems (EOS Topical Meeting on "Blue" Photonics, Aberdeen, 18-19 August 2009).

D. A. DeWolf, "Electromagnetic reflection from an extended turbulent medium: cumulative forward-scatter single-backscatter approximation" IEEE T. Antenn. Propag. 19, 254-262 (1971).

J. Jaffe, New advances in underwater imaging: seeing faster, farther, better (EOS Topical Meeting on "Blue" Photonics, Aberdeen, 18-19 August 2009).

L. S. Dolin, "Propagation of a narrow light beam in a random medium" Izv. VUZ Radiofiz.+ 7, 380-382 (1964).

L. S. Dolin, and V. A. Savel'yev, "Backscattering signal in pulsed irradiation of a turbid medium with a narrow directional light beam" Izv. Atmos. Ocean Phy.+ 7, 328-331 (1971).

L. E. Mertens, and F. S. Replogle Jr., "Use of point spread and beam spread functions for analysis of imaging systems in water" J. Opt. Soc. Am. 67, 1105-1117 (1977).

V. A. Korshunov, "Laser radar equation in the small-angle approximation" Radiophys. Quantum El. 24, 748-755 (1980).

E. P. Zege, I. L. Katsev, and I. N. Polonsky, "Analytical solution to LIDAR return signals from clouds with regard to multiple scattering" Appl. Phys. B-Lasers O. 60, 345-353 (1995).

I. L. Katsev, E. P. Zege, A. S. Prikhach, and I. N. Polonsky, "Efficient technique to determine backscattered light power for various atmospheric and oceanic sounding and imaging systems" J. Opt. Soc. Am. A 14, 1338-1346 (1997).

T. E. Giddings, and J. J. Shirron, "Numerical simulation of the electro-optical imaging process in plane-stratified media" submitted to Appl. Opt. (2008).

F. R. Dalgleish, F. M. Caimi, W. B. Britton, and C. F. Andren, "Improved LLS imaging performance in scattering-dominant waters" Proc. SPIE 7317, 73170E (2009).

A. Laux, R. Billmers, L. Mullen, B. Concannon, J. Davis, J. Prentice, and V. Contarino, "The abc's of oceanographic lidar predictions: a significant step toward closing the loop between theory and experiment" J. Mod. Opt. 49, 439-451 (2002).