Radiation-emitting device and method for detecting an object or a person in the interior of a vehicle

The arrangement has a transmitter (1) for emitting infrared radiation (V), a radiation transmissive cover (2) for the transmitter and a device (3) for detecting radiation reflected or scattered by the cover and for generating a warning signal (Z) depending on the intensity of the reflected or scattered radiation. The device can contain a receiver specially for detecting the reflected or scattered radiation.