Measurement and analysis of optical surface properties for input to ShipIR

摘要

A new standard for the measurement and analysis of optical surface properties for input to the ShipIR model (Vaitekunas, 2002) are developed and tested using paint specimens taken from the unclassified Canadian research vessel (CFAV Quest). The theory and equations used to convert the in-lab surface property measurements into ShipIR model input parameters are described. The resultant data consists of two thermal model input parameters, solar absorptivity (α_s) and thermal emissivity (ε_T); and a series of in-band surface properties, the nominal emissivity (ε), nominal specular reflectance (ρ_s), angular lobe-width (e) and a grazing-angle (b) parameter. Original sample measurements in 2004 are supplemented with new hemispherical directional reflectance (HDR) and bi-directional reflectance distribution function (BRDF) measurements in 2008 to track the changes in the paint specimens and expand the analysis to include additional input parameters to ShipIR. A more rigorous treatment of the BRDF model relates the HDR and BRDF measurements to a single surface roughness parameter (σ).