Abstract: A bundled light beam projected by a light source (21), particularly a laser light source, onto the target is partly reflected back into the measuring apparatus (20), focussed by a concave mirror (61, 81) and split by a beam splitter (26) into two partial beams (25,25'), where the light detectors (28,28'), which in one dimension are at least as long as the partial beams, are arranged at different distances from the beam splitter (26). A linear dependence between the quotient signal and the distance (15) from the measuring apparatus (2) to the target (11) results from the quotient of the detector signals.