Co-aligning laterally displaced radiation beams

Apparatus for co-aligning laterally displaced optical radiation beams from at least a first radiation source output and a second radiation source output, each beam comprising a number of spectral components, the apparatus comprising:

• a collimating element for receiving each of said radiation beams with respective lateral displacements;
• and,
• a combining element for receiving each of said radiation beams passed by said collimating element for co-aligning the radiation beams;
• the apparatus further comprising:
• an optical assembly comprising adjacent first and second optical elements, disposed, in respect of the first radiation source output and the second radiation source output, only in an optical path between the second radiation source output and the collimating element, for spatially separating a plurality of spectral components having different wavelengths by the second radiation source output into the constituent spectral components of radiation prior to passing the radiation to the collimating element,
• wherein the adjacent first and second optical elements comprise substantially the same optical elements having substantially the same optical characteristics.