An optical sensor device (10) is able to be coupled to a window (14), in particular to a windscreen of a motor vehicle. The optical sensor device (10) comprises a sensor unit (12), which includes a emitter (26), a receiver (28) and a light conductor unit (30). By the light conductor unit (30), a light beam (34) emitted by the emitter (26) is coupled into the window (14), coupled out of the window (14) and directed onto the receiver (28). The light conductor unit (30) includes Fresnel lens regions and associated reflecting regions.