Vehicle headlamp

The headlamp unit (1) has a light source (2) for providing a visible light beam and an IR light source (3), with a bimetallic element (4) positioned in the light path between the IR light source and the headlamp glass (6), for blocking the light path unless the light source providing the visible light beam is in operation. The bimetallic element can be provided by a strip or spiral immediately adjacent the visible light source.