Abstract: A two-sided reflector for the reflection of a diffraction-limited optical beam bundle is embodied such that a planar first and second reflection element such as, for example, a reflection film and a cat's eye reflector are arranged with respect to a reference axis of the reflector in such a way that an absolute addition constant of zero results from the targeted choice of the properties of the first and second reflection element and the arrangement thereof with respect to the reference axis for a distance measurement. The distance measurement therefore essentially corresponds to a distance measurement on a natural surface. The distance measurement can therefore be referred directly to the reference axis without additional correction.