Underwater NDE/NDT System for Ship Aluminum Hulls Below the Waterline

To address the Navy"s need for innovative and alternative approaches for nondestructive evaluation and testing (NDE/NDT) for crack detection and hull thickness measurement below the waterline for aluminum ships, Physical Optics Corporation (POC) proposes to develop a new fully functional mobile Underwater NDE/NDT (UNWET) system for large-area non-uniform multilayered thick aluminum/aluminum alloy structures with complex geometry, accurately identifying flaws and defects (corrosion, fatigue degradation, voids) and their precise locations and measurements. UNWET is based on registration of Compton scattered X-ray images of an object, and the reconstruction of its three-dimensional structure using a unique POC-developed Compton imaging tomography technique. UNWET will provide a full exposure time of ~1 min per sq. ft., spatial resolution of ~500 micron, and sensitivity of ~1.0% in density difference. UNWET can define sizes and positions of detected defects with accuracy of 500 micron inside 1- to 3-in.-thick (or even more for high X-ray energies) aluminum hull structures. UNWET can be operated by a diver or mounted on a remotely operated underwater vehicle. In Phase I, POC will demonstrate the feasibility of UNWET using a TRL-4 Phase I benchtop prototype. In Phase II, POC plans to develop and demonstrate a fully functional TRL-6 prototype.