The invention relates to an optical sensor (1) which can be used to detect, unambiguously and with high resolution, the absolute angular position over a full revolution, the number of revolutions performed and the direction of rotation of the rotating object independently of the speed of rotation. The inventive sensor comprises: a polarised light source (2) which illuminates a polariser (3) that rotates proportionally to the rotation of the object to be analysed, a detector (19) which captures the intensity of the beam passing through the polariser, and a signal analyser assembly (20). The invention also comprises a means for resolving indeterminacies (23) by generating a second measurement signal that is phase shifted in relation to the first signal, whereby said second phase-shifted signal can coexist with the first signal or replace same periodically. The invention is of interest to manufacturers and users of angular position sensors.