A light unifier, which comprises a plurality of light sources, particularly
laser diodes, emitting parallel light beams of a rectangular cross-section, for focusing the
light energy of all the beams onto a target area through beam-shaping means, which comprises transverse collimators, means for juxtaposing the emitted beams to form a unified beam, a longitudinal
collimator for longitudinally collimating the unified beam, and means for focusing it onto the target area. The light beams have a transverse and a longitudinal
divergence and the ratio of the transverse
divergence to the longitudinal
divergence is higher than 1. The transverse collimators are placed at such a distance from the sources that, at the point at which the beams reach them, the sum of the short sides of the beams is equal to the long side of each of them at the point at which they reach the longitudinal
collimator. The number of light sources is such as to permit to obtain a unified beam that has a square cross-section and the same divergence on all its sides. Two groups of
laser diodes may be arranged in parallel or mutually perpendicular planes and the unified beams produced by them are focused together onto the target area.