Self-illumination calibration technique for luminescent paint measurements

In a recent article [W. M. Ruyten, Appl. Opt. 36, 3079 (1997)] a theoretical model is presented which accounts for the effects of self-illumination and spectral leakage of a diffusely reflecting test article in luminescent paint measurements. It is shown in the present work how measurements on two, square, painted samples at a range of included angles can be used to check the applicability of the above model for a particular paint, and to determine the spatially averaged reflection coefficient of the paint, Rred, at the emission wavelength. The technique is demonstrated for the pressure-sensitive paint FIB7, yielding Rred=0.79±0.15, where the uncertainty indicates the degree to which the reflection characteristics of the paint deviate from those of a diffuse reflector. The proposed technique constitutes a complete calibration for the correction algorithm developed in the above-referenced article in the case that spectral leakage can be neglected.