A photosensor for a transmitted-light method for detecting the intensity profile of an optical standing wave, with a transparent substrate, with a semiconductor component, and with at least three contacts, is characterized by the fact that two semiconductor components are connected with each other, such that the first semiconductor component and the second semiconductor component each have a photoelectrically active first semiconductor layer, and such that the two photoelectrically active semiconductor layers have a fixed phase relation to each other, which is adjusted by at least one photoelectrically inactive layer.