Abstract: A semiconductor light beam position sensor element comprises a semiconductor layer of successively formed p-, i- and n-type semiconductor layers and an electrically conductive layer on either side of the semiconductive layer. At least one of the conductive layers is made of a transparent material, and at least the other conductive layer and the semiconductor layer are provided with a plurality of common apertures extending in the thickness direction. At least one of the conductor layers is provided with one or two pairs of electrodes of opposite polarity and positioned in its marginal regions. The sensor element is light transparent. A feedback circuit is provided to insure that the incident light is constant.