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Compact Laser System for Airborne Detection of Ocean Mines


OBJECTIVE: Develop a compact and efficient multi-spectral laser system for active multi-spectral imaging (MSI) with four frequency bands across the visible and near infrared (NIR) for detecting surface and near-surface mines in the ocean. DESCRIPTION: The detection of surface and near-surface mines in the ocean during the day or night is accomplished by using advanced Electro-Optic (EO) sensors deployed on a Tactical Unmanned Airborne Vehicle (TUAV). There are many complex issues including: target characteristics, target contrast with the background, and multiple sources of false detections. The objective is to develop a compact multi-spectral laser with four frequency bands across the visible and near infrared (NIR) for use in a multi-spectral imaging (MSI) system to help solve the complex issues related to the detection of ocean mines. Four frequency bands are required for unique spectral discrimination needed to successfully detect ocean mines. At least two bands should span across both sides of the NIR vegetation rise and at least one should provide in-water illumination. The maximum depth is 20 feet in Jerlov Coastal 1 water type. Narrow pulse widths of less than 8 nanoseconds are required to support range-gated operations with imaging sensors. Sufficient pulse power (350 mJ for the water penetration band, 150 mJ for other bands) is required for large area imaging with a high signal-to-noise ratio (SNR). A typical repetition rate is 50 Hz. The Size, Weight, and Power (SWaP) available in the Tactical Unmanned Aerial Vehicle (TUAV) for the laser is 1 cubic foot, 80 pounds, and 1.0 KW at 28 volts DC power. The flight altitude is 3000 feet. PHASE I: Define and develop a concept for a compact multispectral laser system that can meet the performance and the SWaP constraints listed in the description. Perform modeling and simulation to provide initial assessment of concept performance. Phase I Option would include the initial layout and capabilities description to build the unit in Phase II. PHASE II: Development of a prototype based on Phase I work for demonstration and validation. The prototype should be delivered at the end of Phase II, ready to be flown by the government. PHASE III: Integrate the Phase II developed multi-spectral laser prototype with an imager, flight test the complete system, and integrate into the SHD-12-04 FNC program for transition to the ALMDS and/or COBRA acquisition programs. PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Marine Survey, Bathymetry, Search & Rescue REFERENCES: 1. Moran, Steven E., William L. Austin, James T. Murray, Nocolas A. Roddier, Robert Bridges, Richard Vercillo, Roger Stettner, Dave Phillips, Al Bisbee and Ned H. Witherspoon. 2003."Rapid Overt Airborne Reconnaissance (ROAR) for Mines and Obstacles in Very Shallow Water, Surf Zone and Beach."DOI: 10.1117/12.501568 2. Mobley, Curtis D. 1994. Light and Water: Radiative Transfer in Natural Waters. San Diego: Academic Press.
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