Beam combining light source

The invention relates to sources of optical radiation wherein polarized radiation from first (301) and second (302) rows of light emitters (20a-f) is first collimated and combined into two combined beam using first (311) and second (312) rows of collimating and beam re-directing elements (26a-f), respectively, and then polarization multiplexed in a polarizer (86) with the help of a half-wave plate (85) to form a polarization-multiplexed output beam. In order to reduce the footprint, emitters of the first (301) and second (302) emitter rows are disposed in an interleaved, staggered arrangement, and the second row (312) of collimating and beam re-directing elements is disposed in a space between the first emitter (301) row and the first row (311) of collimating and beam re-directing elements. The multiplexed output beam is focused (88) into an optical fibre (99).