A casing for accommodating a first lamp and a second lamp spaced apart from the first lamp, the first and the second lamp forming an array of 5 lamps in a longitudinal direction of the casing comprising: — a basis extending parallel to the longitudinal direction, wherein the basis is equipped with a first mounting position for mounting the first lamp and with a second mounting position for mounting the the second lamp in such a way that the first lamp and the second lamp are 10 capable of directing to a common target to be lit； — an inlet opening for receiving a flow of air to transport heat generated by the first lamp and the second lamp during operation； — an outlet opening for discharging the flow of air including the heat generated by the first lamp and the second lamp during operation； 15 wherein the second mounting position is during operation downstream the first mounting position, wherein the inlet opening is formed by a plurality of apertures arranged at least at one side along the casing, the side of which is oriented transverse to the longitudinal direction of the casing, and wherein at 20 least one of the plurality of apertures is locating between the first and the second mounting position of the first and the second lamp respectively.
