Continuous Wave THz Imaging and Nondestructive Evaluation of Thick Outer Mold Line Paints and Coatings

ABSTRACT: Many nondestructive evaluation (NDE) analysis techniques have tried to address premature failures in outer mold lines on aircraft (OMLs). Imaging through these layers with various electromagnetic and ultrasonic techniques are proven to be deficient. Typically differentiation of layers, structural defects, and chemical composition changes cannot be adequately determined with these techniques. THz Time-domain ranging has shown to be useful in determining layer differentiation but not chemical composition. This is due to the nature of THz time-domain techniques, which are hindered by low spectral resolution and low (nanowatt) power output. Additionally, the prospect of developing a hand-held device that is low-cost and easy to use is improbable for such systems. Traycer has developed a hand-held, 100nW/cm^2 beam sensitivity (<100pW pixel NEP) broadband, kHz frame rate, THz camera (THEIA). THEIA can use reflected phase variation to investigate layer thickness and high spectral fidelity to determine chemical composition of urethane and epoxies, which compose OMLs. Moreover, the high dynamic contrast associated with THEIA allows for imaging curved surfaces. Traycer has assembled a team at The Ohio State University"s Hyperspectral Engine Lab for Integrated Optical Systems (HELIOS) and The Edison Welding Institute (EWI) to work with AFRL program managers to develop a laboratory evaluation tool using the Traycer THz camera THEIA. This strong team represents a large experience base and knowledge of these types of materials and the techniques historically employed for NDE. The ability of the camera to determine integrity of each layer will be evaluated and compared to other types of NDE techniques. BENEFIT: Traycer"s business model is to sell THz imaging components into system-level integrators with established channels to market and application and industry expertise. This allows Traycer to target multiple vertical markets and remain focused on its core value proposition. Current market need for non-contact opaque thin-film measurement systems is estimated at $100M. This includes retrofitting a subset of nucleonic gauging systems in existing markets and new markets in semiconductor QC and fiberglass product QC. These markets see the benefits of THz imaging being the use of non-harmful radiation, non-contact measurement, and nondestructively imaging through opaque materials for both structural and chemical composition. Traycer has proposals and customers in these markets that echo these needs and the associated vertical distribution and sales partners to drive to market. For Traycer, there are immediately large markets that require one or two simple components that are derived and manufactured from Traycer"s core technology and product portfolio. Traycer will access this"low hanging fruit"with a single product in order to demonstrate viability and begin revenue generation before Traycer"s next stage of development. Thin-film measurement systems, like the one outlined in this proposal, is the first step in the market. Larger markets in security, NDE, telecom, and biomedical will eventually be vetted as the technology and products mature.