Photogrammetry: An available surface characterization tool for solar concentrators .2. Assessment of surfaces

In a previous paper, the results of photogrammetric measurements of a number of paraboloidal reflecting surfaces were presented. These results showed that photogrammetry can provide three-dimensional surface characterisations of such solar concentrators. The present paper describes rite assessment of the quality of these surfaces as a derivation of the photogrammetrically produced surface coordinates. Statistical analysis of the z-coordinate distribution of errors indicates that these generally conform to a univariate Gaussian distribution,,while the numerical assessment of the surface normal vectors on these surfaces indicates that the surface normal deviations appear to follow an approximately bivariate Gaussian distribution. Ray tracing of the measured surfaces to predict the expected flux distribution at the focal point of the 400 m(2) dish show a close correlation with the videographically measured flux distribution at the focal point of the dish.