A light signal transmitter and a light receiver for an optical sensor may be used for an industrial automation system. The light signal transmitter has a semiconductor-based light source for generating light. The semiconductor-based light source is disposed in an installation space between outer layers of a multi-layer circuit board. The light emission direction of the semiconductor-based light source is oriented substantially parallel to the layers of the printed circuit board. A deflection unit deflects the light emitted by the semiconductor-based light source in a direction substantially perpendicular to the layers of the printed circuit board. In the case of the light receiver, a light sensor is provided in place of the light source. Such optical sensors can be designed in a particularly flat and installation-friendly manner.