Physical Sciences Inc. (978) 689-0003 20 New England Business Center Andover, MA 01810

Advanced Underwater Imaging

G-3572

James M. Glynn <glynn@psicorp.com>10 October 2008

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Advanced Underwater Imaging Program Overview

A combined hardware/modeling/experimental effort to develop a novel pulsed laser line scan (PLLS) imager – Imaging at longer ranges in turbid water than a conventional CW laser line

scan, in a more compact hardware package

– Reduce size and power requirements to enable implementation in compact unmanned underwater vehicles (UUV’s)

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Highlights

New hardware– Folded scanner geometry

– High power, high rep rate, short pulse laser

New imaging test facility– Large scale test tank with controlled illumination and water optical properties

New performance modeling capability– Laser pulse time history

– Pulsed laser image simulation

Experimental validation of hardware and model performance

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Novel Scanner Design

Folded scanner geometry enables use of single rotating polygon for transmit and receive

Results in more compact design, enabling UUV configurations Prototype functioning at HBOI

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High Rep Rate Pulsed 532 nm Laser

Development at PSI/Q-Peak 2.5W average power, 7 nsec pulses, 350 kHz Enables pulsed gating of target return for backscatter rejection

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Extended Underwater Imaging Test Facility

Unique underwater imaging test facility at HBOI

13 x 7 x 2 m, moving seabed simulator, optical property adjustment and measurement, optics lab

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Developed by Metron Inc. as a variant of their EODES-3 CW laser line scan performance prediction model

Time history of laser pulse in water– Backscatter and target returns from both laser and solar energy

Image simulation– Predicted image quality as a function of user-settable parameters

Validated against experimental data

Use the model as a design aid

New Pulsed Laser Modeling Codes

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Pulsed Laser Performance Modeling – Image Simulation

User sets operational, environmental, system, and target parameters

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CW – PLLS Imaging Experimental Comparison

CW PLLS

0.6 AL

5.1 AL

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CW – PLLS Imaging Comparison

PLLS

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5.1 AL

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Summary

New enabling hardware has been built and tested in new large-scale imaging test facility

New modeling capability to support design has been validated through comparison with full-scale experiments

The pieces are in place to proceed to a targeted development effort for a pulsed laser line scan in a UUV-compatible package