Detection and Classification of Military Munitions Underwater Using Active Fluorometric Imaging (AFI)
Abstract
This work addresses the objectives outlined in the FY 2022 SON in the Munitions Response Program Area, Detection, Classification, and Remediation of Military Munitions Underwater. The idea is that shallow water benthic features in natural environments, both biological and human constructed, often fluoresce when illuminated with blue light and that fluorescence signals contain information regarding objects of interest, such as obstacles to navigation and ordnance as well as marine organisms important for remediation efforts. The approach is referred to as Active Fluorescence Imaging (AFI), meaning that the imaging approach includes a dedicated illumination source to excite fluorescence and a sensor capable of recording the resulting fluorescence signals in high spectral resolution. In this initial laboratory test of the AFI concept, the light source is a dive light equipped with high intensity LEDs emitting at 464 nm and the sensor is a line imager that records the complete visible spectrum (400 - 720 nm) ay high spectral resolution (ECOTONE UHI; www.ecotone.com). The project objectives were to examine the sensitivity and noise attributes of the imager and to test the AFI approach within an experimental water tank under conditions of variable water clarity. The AFI concept is shown capable of imaging fluorescence from submerged targets through turbid water across attenuation lengths, defined as one-way transmission between the camera and target and measured at the illumination wavelength (464 nm), ranging between 2.8 (weak fluorescence) and 6.4 (strong fluorescence. Unlike reflectance signals, fluorescence is unaffected by path radiance (light backscattered by hydrosols), resulting in greater imaging distance and higher target contrast. A Monte Carlo radiative transfer model was developed to simulate the complete experimental setup.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 05, 2020
- Accession Number
- AD1223872
Entities
People
- Robert E. Foster
- Steven G. Ackleson
Organizations
- United States Naval Research Laboratory