An optoelectronic sensor, in particular used for the detection of an angle of rotation, includes a dimensional scale, a light transmitter, which transmits transmission light in transmission light directions, and a light receiver having a light reception surface, which is arranged in such a way that the light reception surface is substantially located between the dimensional scale and the light receiver. The light receiver receives backwardly reflected transmission light as received light. The light receiver also includes a transmission light directing unit. The light directing unit is configured such that a predefined angle of deflection of the transmission light results with respect to the transmission light directions when the transmission light again exits from the transmission light directing unit. The transmission light directing unit is provided in the light receiver; and the transmission light directing unit is composed of at least one aperture which is incorporated into the light receiver.