Concept for maritime near-surface surveillance using water Raman scattering

Area of Science:

• Oceanography
• Optical Engineering
• Remote Sensing

Background:

• Maritime surveillance requires effective methods for detecting objects near the water surface.
• Traditional methods like elastic scattering lidar face challenges with surface reflections and shallow water conditions.

Purpose of the Study:

• To present and validate a novel maritime surveillance concept based on Raman scattering from water molecules.
• To demonstrate the feasibility of using a range-gated scanning lidar for detecting non-water objects.

Main Methods:

• Utilized a range-gated scanning lidar system to detect Raman scattered photons from water molecules.
• Developed a lidar model to simulate the concept and compared its predictions with experimental measurements.
• Investigated the use of UV excitation for potential fluorescence-based discrimination of organic and non-organic objects.

Main Results:

• The lidar model and proof-of-concept measurements showed reasonable agreement.
• The system can generate a sufficient number of Raman photons for near-surface detection with modest lidar parameters.
• The absence or change in the Raman signal effectively indicates the presence of non-water objects, allowing for 2D outline generation.

Conclusions:

• Raman scattering lidar offers a promising approach for maritime surveillance, overcoming limitations of elastic scattering.
• The proposed concept is effective for near-surface object detection and can be enhanced with UV excitation for object characterization.