An optical sensor device has a sensor unit which includes a light emitter (24), a light receiver (26), and a lens plate (12) that is used for coupling a pencil of rays, radiated by the light emitter (24), into and out of the pane and directing it onto the light receiver (26). The lens plate (12) includes a combined Fresnel structure (16a, 16b) having a Fresnel lens structure (18a, 18b) and a Fresnel reflector structure (20a, 20b) on a first surface (12a) facing the light emitter (24) and the light receiver (26), and a Fresnel reflector structure (22a, 22b) on an opposite, second surface (12b) facing the pane. This configuration is especially suitable for use as a rain sensor. Without the light emitter the sensor device is suitable to be used as a light sensor.