Abstract: This paper describes the optical test of the DS1 prototype concentrating surface carried out by CTAER. The DS1 is a parabolic Stirling dish developed under the framework of “SOLARDIS” project. The aim of this investigation was to characterize the DS1 prototype optical parameters. For this purpose the real and the theoretical flux distribution was calculated on a target placed at the focal length and a comparison between them reported about the value of some relevant parameters. The theoretical flux distribution was obtained by photogrammetry technique and ray tracing tools; the real flux distribution was measured by photographic flux mapping technique of lunar images. The results comparison showed that the dish surface had an average optical error of 2.5mrad (it includes errors due to deviation of surface normal vector and the effect of the specularity, but it does not include the sun shape error) and an estimated spillage value of 7%, for this geometry.