An apparatus for receiving an input radiation beam at a beam receiving location and outputting from the beam receiving location one or more output radiation beams. The apparatus comprises: an optical element; and a movement mechanism. The optical element comprises a plurality of portions for receiving the input radiation beam. The movement mechanism is operable to move the plurality of portions so as selectively position each of the plurality of portions at the beam receiving location. When one of the plurality of portions is disposed in the beam receiving location it is configured to receive the input radiation beam and to scatter the input radiation beam so as to form the one or more output radiation beams. A direction of each of the one or more output radiation beams formed by each of the plurality of portions is substantially the same as a direction of a corresponding output radiation beam formed by each of the other portions. One or more properties of each of the plurality of portions differs from that of the other portions such that a power of at least one of the one or more output radiation beams formed by each of the plurality of portions is different to that of the corresponding output radiation beam formed by at least one of the other portions.
